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Adding salt to expand voltage window of humid ionic liquids
Minimizing the electrosorption of water from humid ionic liquids on electrodes
Sheng Bi, Runxi Wang, … Guang Feng
Unconventional interfacial water structure of highly concentrated aqueous electrolytes at negative electrode polarizations
Chao-Yu Li, Ming Chen, … Tianquan Lian
Electrode material–ionic liquid coupling for electrochemical energy storage
Xuehang Wang, Maryam Salari, … Yury Gogotsi
Molecular crowding electrolytes for high-voltage aqueous batteries
Jing Xie, Zhuojian Liang & Yi-Chun Lu
A rational experimental approach to identify correctly the working voltage window of aqueous-based supercapacitors
Willian G. Nunes, Bruno G. A. Freitas, … Hudson Zanin
Decoupled aqueous batteries using pH-decoupling electrolytes
Yun-hai Zhu, Yang-feng Cui, … Xin-bo Zhang
Sustainable power generation for at least one month from ambient humidity using unique nanofluidic diode
Yong Zhang, Tingting Yang, … Qi-Chang He
Theoretically predicting the feasibility of highly-fluorinated ethers as promising diluents for non-flammable concentrated electrolytes
Amine Bouibes, Soumen Saha & Masataka Nagaoka
Ion transport and limited currents in supporting electrolytes and ionic liquids
Maximilian Schalenbach, Yasin Emre Durmus, … Rüdiger-A. Eichel
Ming Chen ORCID: orcid.org/0000-0002-2188-54721 na1,
Jiedu Wu ORCID: orcid.org/0000-0001-7782-40302 na1,
Ting Ye1,
Jinyu Ye ORCID: orcid.org/0000-0003-0521-633X2,
Chang Zhao1,
Sheng Bi ORCID: orcid.org/0000-0001-8804-73531,
Jiawei Yan ORCID: orcid.org/0000-0002-0045-61692,
Bingwei Mao2 &
Guang Feng ORCID: orcid.org/0000-0001-6659-91811
Nature Communications volume 11, Article number: 5809 (2020) Cite this article
Atomistic models
Humid hydrophobic ionic liquids—widely used as electrolytes—have narrowed electrochemical windows due to the involvement of water, absorbed on the electrode surface, in electrolysis. In this work, we performed molecular dynamics simulations to explore effects of adding Li salt in humid ionic liquids on the water adsorbed on the electrode surface. Results reveal that most of the water molecules are pushed away from both cathode and anode, by adding salt. The water remaining on the electrode is almost bound with Li+, having significantly lowered activity. The Li+-bonding and re-arrangement of the surface-adsorbed water both facilitate the inhibition of water electrolysis, and thus prevent the reduction of electrochemical windows of humid hydrophobic ionic liquids. This finding is testified by cyclic voltammetry measurements where salt-in-humid ionic liquids exhibit enlarged electrochemical windows. Our work provides the underlying mechanism and a simple but practical approach for protection of humid ionic liquids from electrochemical performance degradation.
Driven by the demand for the efficient use of intermittent renewable energies and electric vehicles, the development of electrochemical energy storage (EES) devices with outstanding performance has been at the forefront of energy technologies1,2,3,4. Nevertheless, developing safe EES devices with excellent energy density and high-power density remains a significant challenge1,2,3,4. One momentous component for determining the performance of the EES device is the electrolyte. Room-temperature ionic liquids (ILs), with unique properties, including excellent thermal stability, nonflammability, and especially wide electrochemical windows, are an emerging class of candidates for EES devices5,6,7,8,9, such as supercapacitors8,9, batteries10, and solar cells11. However, owing to their hygroscopic nature, ILs can spontaneously adsorb water from the humid environment, regardless of their hydrophilicity or hydrophobicity12. The effect of water in humid ILs at the electrolyte/electrode interfaces has attracted much attention since the system performance is controlled by those electrochemical interfaces. For humid ILs, it has been found that water molecules prefer to accumulate on charged electrode surfaces13,14,15. Very unfavorable to EES devices, the surface-adsorbed water can effectively narrow the electrochemical windows of ILs due to its electrolysis, resulting in performance degradation13,16.
Much of current research has demonstrated that the water electrosorption on the electrode is governed by the working voltage and the association of water molecules with their neighbors (including surface charges, electrode materials, and IL ions)14,17,18. It has been reported that due to the strong interaction with anions, water molecules are excluded from the negatively charged electrode with hydrophilic ILs18. However, it is still an unaddressed issue that, for hydrophobic ILs that have been widely used as electrolytes19,20, they become humid when exposed to the atmosphere12, and unfortunately, their water much favors adsorption on both negatively and positively charged electrodes15,16,18. To avoid compromising their wide electrochemical windows, it is of great importance to minimize surface-adsorbed water and its impact, and thus enhance the voltage window of humid hydrophobic ILs.
Recently, in battery community, the electrochemical window of aqueous Li-ion electrolytes is noticeably enlarged by the "water-in-salt" electrolyte21,22,23,24,25,26. This is ascribed to the nontrivial decrease of water activity since the strong interaction between water and Li+ leads to a large shrinkage of "free" water (i.e., water is not bound with Li+)21,22,23,24,25,26,27. Theoretical work also revealed that the water molecules could be expulsed from the positive electrode with Li+, suppressing the oxygen evolution27,28. Herein, analogous to the "water-in-salt" electrolyte, we investigated the effect of adding Li salt in humid hydrophobic ILs on the ion and water distributions near electrodes, using molecular dynamics (MD) simulation. The simulation system consists of a slab of humid ILs confined between two graphite electrodes (Supplementary Fig. 1). Two types of hydrophobic ILs (1-methyl-1-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide, [Pyr13][TFSI], and 1-butyl-3-methylimidazolium TFSI, [Bmim][TFSI]) were taken with the salt of Li[TFSI]. Details of simulation can be referred to "Methods" and Supplementary Note 1. Our simulations found that the added salt could expand the electrochemical window of humid hydrophobic ILs. This finding was testified by our cyclic voltammetry (CV) measurements. We further delve into the molecular structure and intramolecular interaction of salt-in-humid ILs to understand the mechanism of the electrochemical window expansion, with the help of MD simulations and density functional theory (DFT) calculations, as well as infrared spectroscopy (IR).
Ion and water distributions
We begin our work by dissecting the electrical double-layer (EDL) structure at the electrolyte/electrode interface. Figure 1 illustrates the number density profiles of ions (Li+, [Pyr13]+ and [TFSI]−) and water molecules as a function of distance from the electrode surface with respect to the EDL potential, \({\Phi}_{EDL}\), which is defined as the potential across the EDL relative to the potential of zero charges (PZC). One can find that as the electrode is polarized, the counterion, [Pyr13]+ for the negative electrode and [TFSI]− for the positive electrode, moves closer to the charged surface, in consistence with previous studies29,30, which could be understood by the increased counterion–electrode coulombic interactions29,30. By comparing EDL structures in humid ILs before and after adding Li salt, it can be seen that IL cations and anions form alternating layers extending up to a few nanometers from the electrode surface, and the added salt seems to have a weak influence on the number density profiles of ILs (Supplementary Figs. 5, 6). However, the added Li salt has a quite pronounced impact on the water distribution, particularly in the interfacial region (0–0.35 nm) where water is contact-adsorbed on the electrode surface. Figure 1c and f exhibit water distributions with varying EDL potential at humid [Pyr13][TFSI]/electrode interface and salt-in-humid [Pyr13][TFSI]/electrode interface, respectively. These results reveal that in humid [Pyr13][TFSI], water preferentially accumulates at the charged electrode surface, consistent with previous work of the water-in-IL mixtures14,18,31. In contrast, for salt-in-humid [Pyr13][TFSI], most of the water molecules are found to be notably excluded from the electrode surface, in particular, showing a complete depletion of water under some negative polarizations and large removal of water under high polarizations. More details of the distributions of water molecules and Li+ ions, as well as their evolution with working voltage, are shown in Supplementary Figs. 7–9.
Fig. 1: Ion and water distributions under various potentials.
a–c Number densities of cation (a), anion (b), and water (c) in humid 1-methyl-1-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([Pyr13][TFSI]) as a function of distance from the electrode (z) under various potentials (ΦEDL). d–f The number densities of cation (d), anion (e), and water as well as Li+ (f), in salt-in-humid [Pyr13][TFSI]. The horizontal dash lines (z = 0.35 nm) in (c) and (f) represent the upper boundary of the interfacial region. The contour in (f) indicates the number density of Li+ ions, and the molar salt–water ratio is 1:1. Unit: # nm−3.
Although there are still some water molecules adsorbed on the electrode surface, especially, under large polarizations, such adsorbed water molecules are found to stay closely with the added Li+ ions (contour lines in Fig. 1f). We divide the adsorbed water into free and bound states, based on the number density profile of Li+ ions surrounding water molecule (i.e., water is considered to be bound to Li+ within a distance of around 0.25 nm; otherwise, it is labeled as free water, see Supplementary Fig. 10)21,24,27. We, subsequently, examine how the free and bound water in the interfacial region evolves with different polarizations and adding salt (Fig. 2a). Switching the EDL potential from 0 to −1.5 V, the electrosorbed water is nearly eliminated, and thus unable to participate in the possible electrolysis. This elimination could be ascribed to the Li+–water association that could be evidenced by the similar-located peaks in the number of density distributions of Li+ ions and water molecules (Supplementary Fig. 7b). As the potential becomes more negative, the anions become fewer and further away from the electrode (see the peak height and location of anion distribution in Supplementary Fig. 5), so that Li+ ions get reduced attraction from anions; meanwhile, owing to the stronger electrostatic interaction with the charged electrode, the Li+ ions could overcome the energy barrier by IL ion layer32 and then be attracted to the electrode surface (Fig. 1f). The adsorbed Li+ ions are found to be associated with [TFSI]− and/or water (Supplementary Fig. 11); the adsorbed water molecules are almost bound with Li+ ions, and the proportion of water in the bound state increases with the polarization (e.g., 66.38% at −2 V and 99.99% at −3 V, Supplementary Table 3), so that free water becomes depleted near the negative electrode (middle panel of Fig. 2a).
Fig. 2: Effect of adding salt on the interfacial water and electrochemical window of electrolytes.
a Electrosorption of water from humid 1-methyl-1-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([Pyr13][TFSI]) with/without adding salt. The top, middle and bottom panels are, respectively, the number densities of the total (\(\rho _n^{tot}\)), free (\(\rho _n^{free}\)) and Li+-bound water (\(\rho _n^{bound}\)) in the interfacial region. b Schematic of the effect of adding salt on water electrosorption. c Cyclic voltammograms of HOPG in pure [Pyr13][TFSI] (black line), humid [Pyr13][TFSI] (red line), and salt-in-humid [Pyr13][TFSI] electrolyte (the molar salt–water ratio = 1:1, blue line). Scan rate: 100 mV s−1. Water contents for humid [Pyr13][TFSI] are 4392 and 4474 ppm for MD simulation and cyclic voltammetry experiments, respectively.
As the EDL potential increases from 0 to +1 V, there is always a layer of water molecules adsorbed on the electrode, but they are all bound with Li+ ions localized near the first anion layer (~0.53 nm, Supplementary Figs. 6 and 8). Our DFT calculations show the highest occupied molecular orbital (HOMO) level of the free water is about −8.2 eV, which agrees well with previous work33, while the HOMO level of the Li+-bound water is much lower (around −15.5 eV), which is because that in the bound water the electrons from oxygen atom are donated to the Li+ ion22,34. Thus, the lowered HOMO level by adding salt would help to enhance the oxidation stability of water on the positive electrode. It is worth noting that to quantitatively evaluate such oxidation stability, the oxidation potential could be analyzed from the free energy variation between the reactants and products under positive polarization35,36,37, which has been correlated with the HOMO level: the lower HOMO leads to higher oxidation energy, indicating that more energy is required for the oxidation reaction to occur38,39. Therefore, the calculated HOMO level could be considered as a qualitative approach to estimating the oxidation stability of water in the electrolyte. Moreover, when the voltage is larger than +1 V, Li+ ions are expelled from the electrode surface due to the electrostatic repulsion (Fig. 1f), and consequently, most water molecules are bound with Li+ ions and then taken away from the electrode, resulting in a sharp decrease of free water (middle panel of Fig. 2a). The effect of adding Li salt on water distribution has been illustrated in Fig. 2b.
Therefore, adding salt into humid IL could not only help the water to be repulsed from both negative and positive electrode surfaces but also make the water remaining in the interfacial region become bound with Li+, which could both potentially protect the humid IL from the electrolysis and thus avoid the reduction of electrochemical windows of ILs due to the existence of water. To validate this, we carried out CV measurements for pure [Pyr13][TFSI], humid [Pyr13][TFSI], and salt-in-humid [Pyr13][TFSI] with highly oriented pyrolytic graphite (HOPG) electrodes. Details of measurements can be seen in "Methods" and Supplementary Note 7 (Supplementary Fig. 12). As shown in Fig. 2c, when [Pyr13][TFSI] becomes humid (4474 ppm water, close to 4392 ppm set in MD simulation), its electrochemical window is obviously narrowed down, shrinking both cathodic and anodic voltage limits (from −2.33 ~ 1.15 V to −1.38 ~ 1.01 V). After adding salt (the molar ratio of salt to water is 1:1), the electrochemical window is clearly widened (−2.08 ~ 1.14 V), especially showing a nearly full recovery of positive polarization, compared with pure [Pyr13][TFSI]. This phenomenon is little influenced by changing the scan rate of CV measurements (even down to 5 mV s−1, see Supplementary Fig. 13). The simulation and experiment both demonstrate that adding Li salt into humid hydrophobic [Pyr13][TFSI] does expand its electrochemical window. Additional modeling and experiment were carried out to find the impact of the ratio of Li salt to water, which presents the same trend for the electrosorbed water distribution and the electrochemical window (Supplementary Fig. 14).
Origin of bound water and reinforcement of O–H bond
In order to understand the mechanism of the voltage window expansion by adding Li salt, we first explore the underlying origin of the Li+-bound water and reinforcement of O–H bond. MD simulations of bulk electrolytes were performed to analyze the stretching vibration of O–H bond of water molecules, which was used as the infrared spectroscopy (IR) reporter to monitor the structural change in humid IL electrolytes with adding salt; the spectrum of pure water was treated as the reference. The stretching vibration of O–H bond in pure water exhibits a broad IR spectrum in 3200–3500 cm−1 (the bottom panel of Fig. 3a), corresponding to various hydrogen-bonding environments in water clusters22,23. Comparison of IR spectra of pure water, humid [Pyr13][TFSI] and salt-in-humid [Pyr13][TFSI] demonstrate a distinct modification for the characteristic of the O–H bond stretching vibration (Fig. 3a). To better delineate the change of the stretching vibration of water, three Lorentz peak functions, with each peak representing one type of water, were taken to decompose the IR spectra40,41,42. It is common and expected that the peak position of predicted stretching vibration has some deviation from the experimental result43, and therefore, we, herein, concentrate on the shift of the peak position of the stretching vibration rather than the absolute value. Compared with pure water, IR spectra of humid [Pyr13][TFSI] show the occurrence of new peaks at higher wavenumber (see the bottom two panels of Fig. 3a), which could be ascribed to the reduction of water clusters by the existed IL, in accord with previous work44,45. With adding salt, the peak positions of stretching vibrations shift towards even higher wavenumber when the salt–water ratio varies from 0:1 to 0.5:1 then to 4:1. The IR spectra of O–H stretching vibrations were measured by Fourier transform infrared spectroscopy (FTIR) for humid [Pyr13][TFSI] with adding salt (Supplementary Fig. 15). The peak location shifts of stretching vibrations are shown in Supplementary Fig. 16. Compared with those obtained from MD simulation in Fig. 3a, it can be seen that in spite of the numerical difference, the blue-shifts (i.e., the peak location of stretching vibration shifts towards higher wavenumber) occur after adding salt, in both simulation and experiment. Moreover, IR spectra of O–H stretching vibrations were also obtained from DFT calculations for humid [Pyr13][TFSI] (Supplementary Fig. 17), which confirm the occurrence of the blue-shift with adding Li+ ion. Since all conditions are kept unchanged except the amount of Li+ ions, it is reasonable to ascribe the blue-shift to the Li+ addition.
Fig. 3: Microscopic understanding of the salt effect on water in humid ionic liquids.
a MD-calculated infrared spectroscopy (IR) spectra of O–H bond in pure water, humid 1-methyl-1-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([Pyr13][TFSI]), and humid [Pyr13][TFSI] with different molar salt–water ratios. The gray lines represent IR spectra. The red, pink, and blue regions are the first, second, and third fitting spectra, respectively. The cyan dash lines represent the summation of the fitting spectra. b H-bonds between water molecules (left axis) and between water molecules and ionic liquid ions (right axis). c Interaction energy coming from van-der-Waals and coulombic interactions between water and water, [Pyr13]+ and [TFSI]−. d Interaction energy between water and Li+ (left axis), and the proportion of free water (right axis) as a function of the molar salt–water ratio.
Essentially, the blue-shift indicates that more energy is required to cleave the O–H bond of water into radicals, and then the O–H bond is reinforced, suggesting that with adding salt, water has a lower activity and thus its electrochemical decomposition needs a higher potential46,47,48. The blue-shift is attributed to the destroyed hydrogen bond (H-bond) network42,44. We then computed H-bonds between water molecules themselves and between water molecules and IL ions, defined by the geometrical criterion in Supplementary Fig. 18, as a function of the molar salt–water ratio (Fig. 3b), and found that H-bonds are indeed reduced by adding salt. Especially, H-bonds between water molecules nearly disappear with the molar salt–water ratio over 1.5:1, which can also be evidenced by the dramatically diminished water clusters replaced by the Li+(H2O)n (n = 1, 2, 3, 4) complexes (Supplementary Fig. 19). Furthermore, the H-bond network in the water cluster, following a Grotthuss diffusion mechanism, helps to efficiently separate water electrolysis products49,50,51, enhancing the water activity51. Hence, compared with humid IL, the nearly disappeared H-bond network (Fig. 3b) and largely reduced amount of water clusters (Supplementary Fig. 19b, c) could decrease the activity of water in salt-in-humid IL electrolytes.
The reduced amount of water clusters and the formed Li+-bound water (Fig. 2a) could be fundamentally understood by the interaction energy between water and the other components as well as water itself (calculation of interaction energy can be seen in "Methods"). As presented in Fig. 3c, for humid ILs, the interaction between water and anions is pronounced (about −34 kJ mol−1), followed by that between water and cation (ca. −20 kJ mol−1) and between water and water (around −10 kJ mol−1). Therefore, water molecules tend to be separated from water cluster by ions and exhibit weaker H-bond network, compared with that in pure water, which agrees with the previous work44. As the salt was added into humid ILs, the interaction between water and Li+ rises to be the strongest, and with keeping adding Li+, the interaction between water and Li+ increases gradually and then gets stabilized at about −120 kJ mol−1 (Fig. 3d). Meanwhile, the coordination number of Li+ ions around water increases from about 0.61 to 0.95 as the molar salt–water ratio varies from 0.5:1 to 4:1 (Supplementary Fig. 20). Very differently, the interaction between water and IL ions declines nearly to zero, and even the interaction between water molecules becomes a bit repulsive (Fig. 3c). The resultant interaction makes water molecules isolated from each other and associated with Li+, leading to a sharp decrease in the proportion of free water (Fig. 3d).
Briefly, the added Li salt modifies the environment and property of water molecules on the basis of the predominated interaction between water and Li+ ions, suggesting that water molecules prefer to associate with Li+ ions. Consequently, the H-bond networks between water molecules and between water molecules and IL ions are disrupted, and thus the peak positions of O–H stretching vibrations of water are blue-shifted. This indicates that the strength of O–H bond is increased, and then larger energy is needed to cleave the O–H bond, suggesting that the activity of Li+-bound water is lowered46,47,48. Meanwhile, the free water is largely reduced, since water tends to be bound with Li+. These phenomena arising from the addition of Li salt are responsible for protecting water from electrolysis.
Understanding the effects of adding salt on interfacial water
We then focus on the origin of how salt affects water distributions near the electrode, by analyzing the free energy as a function of the distance to the electrode surface under different EDL potentials. The potential of mean force (PMF), which represents the variation of free energy, was evaluated by using the umbrella sampling method (see "Methods"), where the particle is allowed to rotate (Supplementary Fig. 21)52. For a free water molecule in [Pyr13][TFSI] (Fig. 4a), a well-defined minimum of PMF occurs at a distance of 0.31 nm from the graphite electrode at PZC, corresponding to an accumulation of water near the electrode; with applying either negative or positive polarization, such minimum becomes more pronounced, resulting in the accumulation of water at charged electrodes. Furthermore, the free energy of interfacial water is around −10 and −20 kJ mol−1, respectively, at 2 V and 3 V, deeper than at −2 V (about −5 kJ mol−1) and −3 V (around −9 kJ mol−1), indicating that water would accumulate more at positive electrodes than at negative electrodes. However, the situation is different for Li+ in [Pyr13][TFSI] (Fig. 4b). A deep potential well appears at PZC, ranging from 0.37 to 0.74 nm, which suggests that Li+ ions preferentially stay away from the electrode surface. As for negative electrode (−2 V), although a local minimum occurs at 0.21 nm from the electrode with about −9 kJ mol−1, the lowest potential well shifts to 0.81 nm with around −28 kJ mol−1. Under more negative polarization, the minimum of free energy curve moves further from the electrode. The phenomena that Li+ ions prefer to stay out of interfacial region may be attributed to Li+ ions interacting with anions that form a layer far from the negative electrode (Supplementary Figs. 5 and 7), since the intermolecular energy of ion pair, computed by interaction energies between cation and anions within its solvation shell53, reveals that the Li+-anion interaction (around −370 kJ mol−1) is stronger than that of [Pyr13]+-[TFSI]− pair (about −220 kJ mol−1). Under positive polarization, the potential well shows a distinct valley at around 0.71 nm in the second ion layer, due to a balance between a strong repulsion to the positive electrode and sufficient binding from the first anion layer32, corresponding with the Li+ number density profile.
Fig. 4: Tendency for electrosorption of water, Li+ and Li+-bound water at electrodes.
a–c The potential of mean force (PMF) of water (a), Li+ (b), and Li+-bound water (c) in 1-methyl-1-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([Pyr13][TFSI]) as a function of distance from the electrode. The cyan shaded region (z < 0.35 nm) is considered as the interfacial region.
Then, with adding Li salt, where could Li+-bound water be? We calculated the free energy of a Li+-bound water molecule, as shown in Fig. 4c. Different from the water in [Pyr13][TFSI], the location of the first minimum of PMF at PZC shifts from 0.39 to 0.49 nm. When the EDL potential changes to −2 V, we find a positive potential well near the electrode (about 5 kJ mol−1 at 0.27 nm), which leads to a metastable adsorption18. Meanwhile, the bound water induces a pronounced potential well at 0.85 nm. Accordingly, Li+-bound water molecules prefer to stay far away from the electrode. On the contrary, if the EDL potential is further enlarged (either −3 V or 3 V), different from the single Li+, the water-associated Li+ can pass through the IL layer and become adsorbed on the electrode surface. Therefore, Li+ ions tend to retard water to accumulate on the electrode surface; however, at high polarization, some water can be still dragged to absorb on the electrode surface.
The PMF curves have demonstrated where water, Li+ and Li+-bound water would be predominantly distributed. Specifically, the humid IL exhibits water accumulation at polarized electrodes; with adding salt, water molecules could be largely excluded from the electrode under both negative and positive polarizations. This different behavior is certainly arising from the strong association with Li+ ions.
Mechanism of expanded electrochemical window
With above analyses, the expansion of electrochemical window could be ascribed to that the water is repulsed from the electrode surface, and the water remaining in the interfacial region becomes less active, both originating from the addition of Li salt.
To delve into the effects of adding salt on the activity of interfacial water, we evaluate the behavior of surface-adsorbed water in humid IL and in salt-in-humid IL at the electrode. The atom density profile and orientation distribution of water molecules are analyzed in Fig. 5a–d (the arrangement of interfacial water under more key voltages can be seen in Supplementary Fig. 22). The location and orientation of water molecules in the EDL are found to be sensitive to the applied voltage. Specifically, in humid ILs, as the polarization increases negatively, the interfacial water becomes ordered with the plane of water being more vertical to the electrode surface (Supplementary Fig. 22); meanwhile, under positive polarization, the interfacial water adopts a configuration nearly parallel to the electrode surface.
Fig. 5: Effect of adding salt on the structure of interfacial water in humid ionic liquids.
a The oxygen atom number densities (ρ) of water in humid ionic liquid (IL) (red solid line), and in salt-in-humid IL (blue dash line) at electrodes. The black dotted line is the atom number density of Li+ in salt-in-humid IL. b The hydrogen atom number densities of water in humid IL and in salt-in-humid IL at electrodes. c, d The dipole (c) and normal (d) orientations of interfacial water in humid IL (red solid lines) and in salt-in-humid IL (blue dash lines) at electrodes. θdipole is defined as the angle between the normal of the electrode surface and the water vector, and θnormal is the angle formed between the normal of the electrode surface and the normal of water plane. The black dotted line represents the orientation of bulk water. e, f Schematics of arrangement change of interfacial water under negative (e) and positive (f) polarizations in humid IL due to adding salt. g Infrared spectroscopy (IR) spectra of interfacial water in humid IL and in salt-in-humid IL. The electrical double-layer (EDL) potentials are −2 V and 1 V for negative and positive electrodes, respectively.
Then we move on to the analysis of how adding salt would affect the arrangement of water adsorbed on charged electrodes. At the negative electrode (−2 V), the interfacial water in humid ILs exhibits one sharp peak for oxygen atoms and two peaks for hydrogen atoms (left panel of Fig. 5a, b). Their dipole orientation (with peak located at ~111°, left panel of Fig. 5c) and normal orientation (peak at around 90°, left panel of Fig. 5d) illustrate that most water tends to be perpendicular to the electrode surface, with hydrogen atom pointing to the surface (left panel of Fig. 5e). Such orientations are prone to the hydrogen-evolution reaction28. After adding salt, the water is re-arranged: oxygen atoms of interfacial water remain in the very similar position, while the first peak of hydrogen atoms is shifted away from the electrode surface, from 0.22 to 0.25 nm (left panel of Fig. 5b); although there are still two hydrogen peaks in the interfacial region, the peak of dipole orientation of water shifts from ~111° to ~70° (left panel of Fig. 5c) and the normal orientation is nearly unchanged (left panel of Fig. 5d). These phenomena suggest that the water molecule adjusts its orientation, with its hydrogen atoms pushed away from the electrode. The change of arrangement of interfacial water under negative polarization is schematized in Fig. 5e. Meanwhile, for humid ILs at the positive electrode, the water adopts a configuration parallel to the electrode surface, evidenced by nearly the same peak location (~0.3 nm) of the oxygen and hydrogen atom density profiles and the dipole orientation peaking at 90° with the normal orientation peaking at ca. 15/165° (right panel of Fig. 5a–d); with adding Li salt, although the position of hydrogen atoms changes little, the peak location of oxygen atoms shifts away from the electrode surface (from 0.3 to 0.34 nm), and the peak of dipole orientation moves from 90° to 110°, with a small change of normal orientation (~20/160°). The re-arrangement of interfacial water under positive polarization is schematized in Fig. 5f.
Based on the arrangements of interfacial water under polarization and their changes by adding salt (Fig. 5e, f), we constructed a series of configurations with differently arranged water at graphite electrode (Supplementary Fig. 23) and performed DFT calculations to investigate how the re-arrangement could affect the charge transfer between the interfacial water and electrode (Supplementary Note 11). DFT results uncover that under negative polarization, the arrangement change due to adding salt will allow a few electrons to transfer from the electrode to the interfacial water (Supplementary Fig. 24a), making it more difficult for the hydrogen-evolution reaction. Meanwhile, under positive polarization, the re-arranged water tends to lose a few electrons to the electrode (Supplementary Fig. 24b), facilitating the inhibition of water oxidation. Moreover, MD-obtained O–H spectra in the interfacial region are also found to vary with adding salt (Fig. 5g), that is, the peak positions of O–H stretching vibrations of interfacial water in salt-in-humid IL are shifted towards higher wavenumber, indicating that O–H bond becomes more stable than that without salt46,47,48.
We further testify the generality of the conclusion that the adding salt expands the electrochemical window of humid hydrophobic ILs, by combined simulation-experiment work of another hydrophobic IL [Bmim][TFSI]. Although the cations [Pyr13]+ and [Bmim]+ are different in terms of their molecular structure, shape/size, and weight, observations in simulation and experiment follow the same trend (Supplementary Figs. 25 and 26), where water molecules stay away from the electrodes owing to the presence of Li+ and the electrochemical window is enhanced (with increases of 0.51 V and 0.21 V, respectively, for negative and positive polarization), compared with humid [Bmim][TFSI].
We have investigated the effect of adding salt in humid hydrophobic ILs on distributions of ion and water at the electrode surface. Combining MD simulations, DFT calculations and CV measurements, we found that the electrochemical stability window of salt-in-humid ILs is indeed expanded, compared with the humid one. MD simulations and DFT calculations provide a molecular understanding of how and why adding salt could dramatically enhance the electrochemical window of humid ILs. Such enhancement is ascribed to water repulsed from the electrode surface and the lowered activity of water remaining in the interfacial region, by adding Li salt.
The water is found to have a stronger association with Li+ than IL ions. Therefore, since Li+ ions mostly prefer to stay away from the electrode surface, water tends to be pulled away from the electrode under positive and moderately negative polarizations, extremely reducing the water in the interfacial region. For water molecules still adsorbed on the electrode surface, most of them are bound with Li+, resulting in significantly decreased activity, since the strength of O–H bond in bound water is increased due to the association with Li+, and thus more energy is needed to split the O–H bond48. Meanwhile, the added Li+ modifies the arrangement of adsorbed water by changing its orientation and atom position. Explicitly, the arrangement change of interfacial water under negative polarization leads to a reduction of electrons transferred from the electrode to water, making it difficult for the hydrogen-evolution reaction to occur; the oxygen atom is pulled away from the positively charged electrode, protecting water from electrolysis. The lower HOMO level of bound water is a complementary mechanism for the thermodynamic manner to improve electrolyte oxidation stability under positive polarization22,34.
Although the above understanding is revealed by classical MD simulation joint with DFT calculations, and could qualitatively explain the expansion of electrochemical window, the molecular simulation with reactive force fields, which could directly mimic the processes of chemical bond breaking/forming, may give a quantitative prediction of electrochemical window expansion. Moreover, it should be noted that the approach of adding salt is tested in two hydrophobic ILs herein, and taking into account the cost of lithium salt, more ILs and cheap salts54,55 are preferred in further investigation.
The findings reported with the concept of salt-in-humid ILs could extend the comprehension of the preferential species electrosorption, and provide a guideline for minimizing water adsorption and altering the structure and property of adsorbed water. The mitigation of adsorbed water and its impact could improve the practical performance of EES systems as an electrochemical window of humid hydrophobic ILs can be enlarged, and may also benefit other applications such as IL gating56, lubrication57, and electrowetting58. The understanding of adding salt to expand the electrochemical window, including the decrease of interfacial water, reinforcement of O–H bond, and water re-arrangement, as well as the lowered HOMO level of bound water, may be responsible for the working mechanism of water-in-salt electrolytes21,22,23,24,25,26 in battery and supercapacitor.
MD simulation
MD simulations were utilized to investigate the effect of added salt on the ion and water distributions in the EDL of humid IL. Specifically, we employed MD simulation of hydrophobic IL-water-salt mixtures confined between two atomically flat graphite electrode surfaces as shown in Supplementary Fig. 1. All-atom model was taken for two hydrophobic ILs ([Pyr13][TFSI] and [Bmim][TFSI])59,60; the SPC/E model was adopted for water61. The OPLS force field was used for Li+ ion62; carbon atoms in the electrode were modeled using the force fields in ref. 63. The sizes of all simulation systems were chosen as long enough to reproduce the bulk-like state of electrolytes in the central region between two electrodes. The number of the species and the distance between two electrodes are given in Supplementary Table 1 for all systems.
All simulations were performed in NVT ensemble with MD package GROMACS64. The temperature was controlled through the Nosé–Hoover thermostat65,66 at 333 K with coupling constant of 1.0 ps. A cutoff distance of 1.2 nm was employed for the van-der-Waals term via direct summation. The long-range electrostatic interactions were computed via PME method67. An FFT grid spacing of 0.1 nm and cubic interpolation were used to compute the electrostatic interaction in the reciprocal space. A cutoff length of 1.2 nm was adopted in the calculation of electrostatic interactions in the real space. The leapfrog integration algorithm was taken to solve the equations of motion, with a time step of 2 fs. Specifically, in order to ensure an adequate description of the electrode polarization effects in the presence of electrolytes, constant potential method2,68,69 was implemented to allow the fluctuations of the charges on electrode atoms. To guarantee the accuracy, the electrode charges were updated on the fly every simulation step. For each simulation, the MD system was first heated at 700 K for 3 ns and then annealed to 333 K over a period of 2 ns, following by another 10 ns to reach equilibrium. After that, a 20-ns production was performed for analysis. Each case was repeated three times with different initial configurations to certify the accuracy of the simulation results.
PMF calculation
PMF represents the variation of free energy and is evaluated by the umbrella sampling method70. A series of initial configurations are generated, and each of them corresponds to a location where the molecule is restrained via a harmonic potential. It could be understood as the molecule is bound by a spring and moves back and forward around a given position, traveling freely along the plane parallel to the electrode surface. Rather than being fixed, the molecule is allowed to rotate, experiencing all possible orientations. With the weighted histogram analysis method71, the PMF is subsequently extracted. To determine the PMF profile for water, Li+ and Li+–H2O, one water molecule, Li+–TFSI− pair, and Li+(H2O)–TFSI− pair are, respectively, added into the ionic liquid system, since the PMF for one particle (i.e., an atom, molecule, ion or group) is enough to reveal its free energy distribution and the origin of its density distribution70,72.
Interaction energy calculation
We characterized the interaction energy between components A and B based on MD-obtained trajectories. Technologically, the A–B interaction energy, coming from van-der-Waals and coulombic interactions, was calculated between component A and component B surrounding A, using a cutoff method (1.2 nm). Such analysis has been used in previous modeling work73,74.
Quantum molecular orbital analysis
DFT calculations on the molecular orbital of water and water/Li+ complexes were performed with the Gaussian 09 program (revision, D.01)75. The basis sets implemented in the Gaussian program were used. The geometries of water and water/Li+ complexes were fully optimized using B3LYP/DFT method with 6–311 G** basis set. Based on their optimized geometries, the HOMO energy levels were calculated at the same level.
Experimental materials and measurements
ILs [Pyr13][TFSI] and [Bmim][TFSI] were purchased from IoLiTec in the highest available quality (99%); salt LiTFSI (99.95%) was purchased from Sigma-Aldrich. Prior to each measurement. ILs were purified through ultrapure water (Milli-Q, 18.2 MΩ·cm) and then vacuum-dried for 24 h at 80 °C in a glovebox filled with ultrapure Argon (Linde Industrial Gases, 99.999%) to remove water as much as possible, and then used as dry ILs. The capacity of pure ILs [Pyr13][TFSI] and [Bmim][TFSI] to absorb water from environment was examined under constant humidity (43.72 ± 2.45% humidity for [Pyr13][TFSI] and 43.00 ± 1.68% for [Bmim][TFSI], see Supplementary Fig. 2). Humid ILs were prepared via adding ultrapure water into ILs. Salt-in-humid ILs were prepared by adding ultrapure water and LiTFSI into ILs, and then the mixtures were stirred up for 12 h till homogeneous solutions were formed. Detailed information of electrolyte preparation can be seen in Supplementary Note 2 with Supplementary Table 2. Even when the molar salt–water ratio reaches 4:1 (the highest used in this work), the solubility limit of LiTFSI in such two humid ILs still does not occur in the experiment (Supplementary Fig. 3)76. Water contents were determined by Karl Fischer Coulometer (Metrohm, KF-831)77. Cyclic voltammetry measurements were carried out in a glovebox by using an Autolab electrochemical workstation (Eco Chemie, The Netherlands). HOPG was used as working electrode. A piece of tape was pressed onto the flat surface and then pulled off to form a newly cleaved clean surface for electrochemical measurements. A scanning tunneling microscope image for HOPG (Supplementary Fig. 4), conducted on a scanning probe microscope (Bruker Corp., multimode 8), reveals that the proportion of carbon atom number at the step edge is estimated to be ~2.1 × 10−4, indicating that the effect of step edges is negligible in this work. Silver wire and platinum wire were used as reference electrode and counter electrode, respectively. The potentials of Ag wire in all electrolytes were calibrated with respect to an Ag/AgCl reference electrode. The time dependence of the open-circuit potential (OCP) of Ag quasi-reference electrode versus Ag/AgCl electrode in different solutions was measured (Supplementary Fig. 12), and such OCPs for different electrolytes were listed in Supplementary Table 4. The electrochemical cell used for measurements was a sealed one, which was isolated from the environment, and CV measurements were typically completed within half an hour, so that the change of water contents can be negligible. FTIR measurements were conducted on a Nexus 8700 spectrometer (Nicolet) equipped with a liquid-nitrogen-cooled MCT-A detector. A commercial demountable liquid cell (Harrick Scientific Corporation) was used. The sample was prepared in a glovebox and transferred to a spectrometer with a sealed vessel. The sample preparation for IR measurements was completed within two minutes. Then, an unpolarized IR radiation sequentially passed through two CaF2 windows with a thin-layer solution (25 μm). The IR transmission spectrum of the sample was taken from 1111 to 4000 cm−1 with a resolution of 4 cm−1 and averaged 100 times.
The data that support the findings of this study are available from the corresponding author upon request. Source data are provided with this paper.
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G.F., M.C., T.Y., C.Z., and S.B. acknowledge the funding support from the National Natural Science Foundation of China (51876072 and 51836003). J.W.Y., B.W.M., J.D.W., and J.Y.Y. acknowledge the support of Natural Science Foundation of China (21673193, 22072123, and 21727807). G.F., M.C., T.Y., and C.Z. also thank the Hubei Provincial Natural Science Foundation of China (2020CFA093). The computation is completed using Tianhe II supercomputer in National Supercomputing Center in Guangzhou.
These authors contributed equally: Ming Chen, Jiedu Wu.
State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology (HUST), 430074, Wuhan, China
Ming Chen, Ting Ye, Chang Zhao, Sheng Bi & Guang Feng
State Key Laboratory of Physical Chemistry of Solid Surfaces, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, 361005, Xiamen, China
Jiedu Wu, Jinyu Ye, Jiawei Yan & Bingwei Mao
Ming Chen
Jiedu Wu
Ting Ye
Jinyu Ye
Chang Zhao
Sheng Bi
Jiawei Yan
Bingwei Mao
Guang Feng
G.F. conceived this research. G.F. and J.W.Y. designed the work of simulation and experiment, respectively. M.C., T.Y., C.Z., and S.B. carried out all simulations; M.C. did all DFT calculations. J.D.W., J.Y.Y., J.W.Y., and B.W.M. carried out the experiment. M.C. drafted the paper. All authors contributed to the analysis and discussion of the data and revision of the paper.
Correspondence to Guang Feng.
Peer review information Nature Communications thanks Markus Valtiner and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Peer reviewer reports are available.
Publisher's note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Peer Review File
Source data
Chen, M., Wu, J., Ye, T. et al. Adding salt to expand voltage window of humid ionic liquids. Nat Commun 11, 5809 (2020). https://doi.org/10.1038/s41467-020-19469-3
Chao-Yu Li
Tianquan Lian
Engineering a passivating electric double layer for high performance lithium metal batteries
Weili Zhang
Yang Lu
Kai Liu
Recovering the electrochemical window by forming a localized solvation nanostructure in ionic liquids with trace water
Jianing Meng
Meng Ye
Xingbin Yan
Science China Chemistry (2022)
Editors' Highlights
Nature Communications (Nat Commun) ISSN 2041-1723 (online)


After writing her dissertation on the psychological experience of climbing the world's highest peak, Mollie decided to take on the mammoth challenge herself – becoming one of the youngest British women to reach the summit in May 2012.
"The idea of climbing Everest came in my final year at UWE Bristol. I was writing my dissertation in the area of sports psychology - 'The psychological experience of climbing Mount Everest'. About half way through my first interview I decided that Everest was something I needed to experience for myself.
"I knew from my dissertation that I had to take a really pragmatic approach to climbing Everest and not focus too heavily on the summit. It's a two month expedition, so just taking it a day at a time and seeing everyday on the mountain as an achievement was totally important."
" My course at UWE Bristol gave me massive scope to tailor my learning to my interests, through great module choices and the ability to be so specialised with my final year project. UWE Bristol played a massive role in my training. As soon as I had decided to climb Everest, I went down to the Centre for Sport and had a meeting with Steve Lock, the strength and conditioning coach. Over the next 10 months Steve trained me to be in the best possible shape to cope with the physical challenges I would face on Everest.
"Securing sponsorship was nearly as hard as climbing the mountain itself! I had to raise about £25,000 to join an expedition and being a poor university student, I didn't have this. I sent out more than 30 sponsorship proposals each week and got about 30 rejections each week. This went on for about eight months and then, four weeks before I was meant to be leaving for Everest, my sponsorship finally came through.
"I am one of the youngest British climbers to summit Everest, I was 21 when I summited. There was a record up for grabs on the mountain this year, to be the youngest British woman to summit. However, there were two other girls on the mountain (Becky Bellworthy and Leanna Shuttleworth), both good friends of mine and both younger than me, who also successfully summited. It's an amazing feeling to have stood on top of the world."


text:
Man arrested after disturbance in Prestonpans had a knife and roughly 1000 unknown tablets in his possession
Scottish fugitive Jamie Stevenson among UK's 12 most wanted men
Edinburgh Council elections: New councillors should cooperate for the good of the city, not stoke 'toxic' feuds – Susan Dalgety
There will be a lot of new faces on Edinburgh City Council come May.
By Susan Dalgety
Monday, 10th January 2022, 12:30 pm
Graham Hutchison is among seven Conservative councillors who will stand down at the elections in May
Six of Labour's veteran councillors have already said they are retiring from public office. And seven Conservative representatives have thrown in the towel, the latest being the party's transport spokesman, Graham Hutchison.
Councillor Hutchison told this newspaper that "the atmosphere in the council is absolutely toxic". And he complained that the ruling SNP/Labour administration does not take into account that opposition councillors are there to "do good" for their residents, just as they are.
There has been a spate of complaints recently about the council's leadership. Some are no doubt gratuitous.
But there does seem to be something amiss in Edinburgh. It might just be the early stages of the election campaign that will end on May 5 when the voters will decide who runs the city for the next five years.
Here are five times things got heated at Edinburgh City Council
At the last election, the Tories just won the popular vote, beating the SNP into a close second place. But the Nationalists won one more seat with 19 councillors to the Tories' 18. Labour was third with 12 seats.
Instead of acknowledging that the Tories have considerable support across the city, the SNP/Labour administration has largely dismissed them as irrelevant, and by doing so has ignored the people who voted for them.
Council elections are no longer based on the crude first-past-the post system. There are now 17 multi-member wards, with up to four councillors elected for each. Councillor Hutchison represents the Almond ward – which includes Barnton and Muirhouse – along with two Lib Dems and an SNP councillor.
The Cosla guide to becoming a councillor insists that working with the other councillors in your ward is a key feature of the job, and by all accounts Edinburgh councillors work reasonably well together at the community level.
So why can they not bring that same collegiate approach to the City Chambers? Party differences matter of course, but Labour didn't hesitate to do a deal with the SNP in exchange for a handful of leadership positions.
Let's hope that the 2022 intake of councillors, whatever their allegiance, can work together on behalf of the city and not solely their narrow party interest.
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redpajama_set_name: RedPajamaCommonCrawl


Tau (shown in red) is one of the microtubule-associated proteins and specifically localized to the axon (cell body and dendrites shown in green), where it is thought to contribute to the axonal structure and protein trafficking. However, in pathological conditions, such as in Alzheimer's disease, tau mis-localizes to dendrites and forms aggregates called the neurofibrillary tangles. We investigate the molecular mechanisms that determines the axonal localization in normal and how it is disrupted in diseases.


DVDGo is a DVD image grabber software, it can grab images from your DVD VOB files, you can save these images to Windows Bitmap files or JPEG files. DVDGo Lite is not a complete DVD Player, it cannot play audio of DVD files, it can only play video files, so if you need a DVD player, please select WinDVD or PowerDVD.
Create Redbook CD-A audio CD's that can be played in any stand alone CD or DVD player or create MP3 CD's to be played in MP3 players or on a computer. Record any audio that can be played through your computer's sound devices and save it as MP3, Wav, VOX, Raw, G726 or OGG Vorbis formats.
MoodBook is a tiny Windows utility that brings art to your desktop and sets a tone for your daily mood and emotions! With MoodBook your desktop looks like an art gallery changing art expositions either automatically, at regular time intervals, or manually, with a click. Each exposition has either a tranquil, neutral or vivid background and a picture of art in the center. A basic set of art delivers over 50 original digital art images of the following art styles: post-impressionism, modernism, abstractionism, surrealism and computer graphics art. Additionally, MoodBook is designed to help you control your sense and mind, set a tone for your mood, and adjust your mental state. Abstract art pictures have a major impact on your perception, as well as, the desktop background itself sets a tone for your mood, influencing deeply with the color. MoodBook is free!
A powerful tool to backup DVD movies to VCD/SVCD with just one click on your PC! Copy DVD movies to CD-R discs, convert DVD to VCD/SVCD, with DVDCopy it couldn't be easier! Copy DVD movies using your CD writer with just one click. Support DVD to VCD image, VCD image to CDRW. Support almost all popular CD writers. Only need up to 4GB hard disk space. Small size,only 1MB!
Create an attractive CD catalogue system. With an ordering system, order history and the abitlity to have price brackets.


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text:
Q: Insertar datos desde Visual Studio a SQL Server Como puedo solucionar este problema al momento de insertar datos desde Visual Studio.net al SQL
Este es mi codigo que utilice:
Imports System.Data.SqlClient

Public Class Form1

Private Sub BtnInsertar_Click(sender As Object, e As EventArgs) Handles BtnInsertar.Click
    Dim conexion As SqlConnection
    conexion = New SqlConnection("server=USER-PC; database=base1; integrated security=true")
    conexion.Open()

    Dim placa As String = TxtPlaca.Text
    Dim marca As String = TxtMarca.Text
    Dim cilindraje As String = TxtCilindraje.Text
    Dim color As String = TxtColor.Text
    Dim modelo As String = TxtModelo.Text

    Dim cadena As String = "insert into automovil (placa, marca, cilindraje, color, modelo) values (" & placa & ",'" & marca & "', " & cilindraje & ",'" & color & "','" & modelo & "')"

    Dim comando As SqlCommand
    comando = New SqlCommand(cadena, conexion)
    comando.ExecuteNonQuery()

    MessageBox.Show("Datos Ingresados Correctamente")

    TxtPlaca.Text = ""
    TxtMarca.Text = ""
    TxtCilindraje.Text = ""
    TxtColor.Text = ""
    TxtModelo.Text = ""

    conexion.Close()
End Sub
End Class

Pero me detecta un error en la esta linea:
comando.ExecuteNonQuery()

como puedo solucionarlo, soy principiante

A: El error es bastante claro, estas intentando insertar un valor explícito en la tabla automovil en una columna que no lo permite, posiblemente placa, por que la misma es del tipo IDENTITY, lo que en español básico significa que es una columna auto-numérica, es decir, le corresponde al motor la actualización de la misma, no puedes explicitamente configurarle un valor. Lo que debes hacer es quitarla de la sentencia de INSERT y dejar que la base de dato se encargue de establecerle el valor. Si eventualmente necesitarás recuperar el valor de esta columna una vez insertada puedes utilizar la función SCOPE_IDENTITY().
Obviamente si placa es el IDENTITY como imagino, en tu ejemplo debieras hacer esto:
Dim cadena As String = "insert into automovil (marca, cilindraje, color, modelo) values ('" & marca & "', " & cilindraje & ",'" & color & "','" & modelo & "')"

Aclaración: cuando digo que no puedes establecer el valor de esta columna en realidad debería decir que no es recomendable hacerlo en la mayoría de los casos, bajo ciertas circunstancias puedes hacer un SET IDENTITY_INSERT automoviles ON;, insertar el valor específico a la columna y volver todo a la normalidad con SET IDENTITY_INSERT automoviles OFF;, pero en tu ejemplo, no tiene ningún sentido hacerlo así.

redpajama_set_name: RedPajamaStackExchange


text:
Home News Hamilton won't ease off, 'not how my mind works'
Hamilton won't ease off, 'not how my mind works'
Date published: December 21 2020
Lewis Hamilton admits that he could sit back and think 'I'm pretty good', but that just isn't how his mind works.
The Briton equalled Michael Schumacher's record of seven World Championships in a dominant 2020 campaign, while he also surpased the German's benchmark for most career wins with Hamilton now having 95 to his name.
So, at this stage, it would be easy for Hamilton to sit back and revel in his achievements, but actually he is more focused on the threats that could come from rivals and how he stays ahead.
He also warned that the moment Mercedes as a team start to "rest on our laurels", then they could be heading down the wrong path.
"I think there's an under-appreciated workload that goes on for the people in the background and for the drivers in terms of interpreting the tools that we have," he told Autosport.
"The detail to which we go to try to adjust these small things – a millimetre here, half a millimetre there of ride, for the shift of the front end, whatever it may be. But each year, I get this new set of tools and have to study like anybody has to study to be on top of those things [and] try to be ahead of the [other] drivers.
"I personally just don't think, 'Yes, I have six [now seven] world titles'. I could just sit back on them and think, 'I'm pretty good'. But that's not how my mind works.
"My mind is like, 'jeez, these guys are chasing me, how do I stay ahead? How do I stay steps ahead? How do I help push the team to stay steps ahead?' And that's a really big process, because we can easily go down the wrong road – if we rest on our laurels.
"If you look at last year, it made the races so much harder for me when I didn't perform to the best of my ability, generally, on the Saturdays.
"It just meant that the pressure was even higher for the Sunday, which I think is sometimes unnecessary pressure. So, this year, being able to work on that, with Bono [Peter Bonnington] and the engineers to make sure we're delivering better performances on the Saturdays, that's been a relief [in that it] makes Sunday generally, not easier, but just less pressured."
Your 2020 BBC Sports Personality of the Year! ⭐
Congratulations @LewisHamilton! 👏👏#SPOTY #SPOTY2020 pic.twitter.com/PvPv7WkGOP
— Mercedes-AMG PETRONAS F1 Team (@MercedesAMGF1) December 20, 2020
There's no denying that, armed with the W11, Hamilton reached a new level of dominance in 2020, though he says it's the defeats which make him stronger as a driver, rather than the wins.
There's no greater example than the 2016 title battle with Nico Rosberg, the only season of the turbo-hybrid era where Hamilton has not won the World Championship.
"I am definitely one of those people that thinks the losses have made me stronger than the wins," he confirmed.
"I definitely say that the hardest races are the ones that you grow from most. And that's not only on the driver's side, that's also with all the engineers and mechanics – we feel it for days. And it definitely feeds you to come back and fight faster, harder the next time."
"I'd be lying if I was to say that I wasn't improving, I mean, if I wasn't getting the results, and then perhaps it wouldn't be improving, but I definitely am having to… I can't stay still. This sport doesn't stay still, technology is constantly evolving."


Safaricom has rolled out "Asante Data Sunday" in which customers will get back all the data they use on Friday 23rd and Saturday 24th November 2018. The move by the telecommunications company is part of the 18 year anniversary "Nawe Kila Wakati" campaign designed to thank our customers for their trust and loyalty over the years.
Subscribers will be required to dial *444*20# to view the accumulated data usage and to check their bonus data balance. The bonus data will be consumed first before other existing or purchased bundles. The promotion is open to all Safaricom PrePay, Hybrid and PostPay customers with all eligible customers being automatically enrolled in the promotion and to receive the bonus.
"We remain mindful that the success we have achieved in building a world-class mobile broadband network has only been possible due to the immense trust of more than 17 million customers who use our data network every month," said Charles Kare, Director – Consumer Business, Safaricom.
As part of its 18th-anniversary campaign, Safaricom also recently announced a promotion where customers can call for KES. 1 per minute. Customers will similarly benefit from a free 1 GB data bundle and a special KES. 1 per minute call rate during their birthdays.
In the last 18 years, Safaricom has expanded its network to provide broadband 4G+, 4G and 3G coverage to 91 percent of the population and 2G coverage to 96 percent of the population. The firm was the first in the region to roll out a 4G+ network and the first in the country to deploy 4G and 3G networks.
Safaricom sued over Okoa Jahazi charges.
How BI Plays an Essential Role in Company Culture?
Microsoft Rolls Out Nokia X2 In Kenya.


The finishing section of the company has all the necessary infrastructures for the final development of the fabrics. We reach up to 340 cm. We have all kinds of finishes, Sanfor, Tumbler, resins.
We have all kinds of dyeing machines to carry out the highest performance in the dyeing of fabrics and offer our customers the range of colors, from our colorimeter, which the market requires us. We have Jiggers, Autoclaves, Multiflows … etc, to achieve maximum quality in both flat and knitted fabrics.
Colorprint Fashion has the latest technology in digital printing. Great diversity of machines give us the ability to stamp any type of fabric (flat and knitted) with any composition (either cotton, polyester, or any type of mixture) because our machinery have the possibility to print in reactive inks, pigments or dispersed and wide from 140 to 330 cm. We have the best inks in the market with which we get the best degrees of fastness to both rubbing and washing.
The Company has 4 rotary printing machines with their corresponding drying and color fixing processes. The width of the machines reaches 320 cm, and possibility of printing different sizes of rapport which offers the possibility of making any drawing with standardized measurements, also allows us to use up to 17 cylinders of the same drawing.
45 years dedicated to printing, dyeing and finishing fabrics.
Colorprint Fashion began its industrial activity in mid-1996. The aim of this company has been from the beginning to offer finishes in the stamping of fabrics according to the current demands of the market in quality controls. The promoters of the project contribute more than 45 years of experience in the sector of the stamping. In addition to experience, Colorprint Fashion has the latest machinery for printing, textile finishing and dyeing of fabrics. Human resources are one of the most important points of a company. This is how COLORPRINT understands it, so that its 150 professionals, knowing their trade, put their effort to transmit their young dynamism in their task. The result is a great technical solvency able to satisfy any demand for stamping, no matter how demanding. COLORPRINT knows that the successes of the clients are their own successes.
Composed by a group of qualified professionals in textile design, this section is equipped with the most modern computer equipment on the market and has the most updated professional programs in the treatment of the image.


text:
Микита Скуба (псевдо: «Лайдака») (1916, с. Бичаль Костопільського районну Рівненської області — ,(15 березня ?) біля с. Літвиця Дубровицького р-ну Рівненської обл.)  — сотник УПА, курінний загону ім. Колодзінського Воєнної Округи «Заграва». Лицар Золотого Хреста Бойової Заслуги 1-го кл..

Біографія

В березні 1943 р. був арештований німцями і перебував у Рівненській в'язниці, та через короткий час організував і здійснив втечу.

Вже 4 квітня 1943 року брав участь у бою сотні УПА під командою «Чайки» з німцями в с. Постійне Костопільського району Рівненської області.

В серпні 1943 р. став командиром 2-х сотень рейдуючої Бойової групи УПА «Бористена»; з вересня 1943 р. — командир загону УПА ім. Колодзінського ВО «Заграва».

Станом на січень 1944 р. виглядав наступним чином: «32-35 років, високого зросту, худий, лице видовжене, ніс прямий, волосся русяве, очі сірі, поранена ліва рука», добре володів німецькою мовою.

Загинув у бою з підрозділом ВВ НКВС біля рідного села 11 березня 1944 р., про що занотовано у відповідному звіті: «будучи раненим у ліве рам'я, стріляв ще одною рукою з коліна і командував боєм, доки не впав із другої кулі».

Похований у с. Літвиця Дубровицького р-ну Рівненської обл.. Посмертно отримав звання сотника УПА (17 березня 1944 р.). Восени 1944 р. на його честь названо бригаду УПА.

Бої
Перелік боїв та сутичок, у яких брав участь Микита Скуба.

Нагороди

 Згідно з Постановою УГВР від 16.10.1948 р. і Наказом Головного військового штабу УПА ч. 3/48 від 23.10.1948 р. хорунжий УПА Микита Скуба – «Лайдака» нагороджений Золотим хрестом бойової заслуги УПА 1 класу.

Див. також
   † Мартиролог загиблих діячів ОУН та УПА †
  Командири УПА
Лицарі ОУН та УПА

Джерела та література

 ГДА СБУ. – Ф. 13. – Спр. 376. – Т. 60. – Арк. 266-267.

Посилання

 О. Абдуллін, П. Воробей. Заграва: роман. Київ: Український письменник, 2005
 Благодійна ініціатива «Героїка»: Поховання воїнів УПА у Літвиці
 Володимир Ковальчук, Скільки ж солдатів було в УПА? Секрети розкриває Клим Савур

Примітки

УПА-Північ
Вояки Української повстанської армії
Уродженці Костопільського району
Діячі УПА
Загинули в боях Другої світової війни
Померли в Дубровицькому районі

redpajama_set_name: RedPajamaWikipedia


Placement in a Special Education setting. District 88 has self contained programming on each campus for students with severe academic, behavioral, and cognitive needs. District 88 also offers the LIFE program for students needing transition services ages 17-21.
Ask for additional time to consider important decisions if you're uncomfortable making them on the spot at the meeting or want to get additional input. Saying, "I don't know what you mean," is a demonstration of confidence and competence. Staff are more than willing to explain in a different manner. It's our job to make sure that you leave having all of the information you desire.Work with staff to engage your student in participating in their meeting. At the high school level, students need to take an active role in their IEP meeting and be part of the problem solving process.
Finally, please consider joining our Special Education parent advisory, the WIN organization. This group of parents of children with a disability meets one night a month. The meeting format typically involves a presentation, speaker, or workshop, as well as an opportunity to network with other families.
- Notify the Special Education Department at 630-530-3431 so we can get your student's IEP documents ready to take with you to your student's new school. The new school will need these to appropriately place your student and meet their specific needs. Take these documents with you when you first go to the new school to register your student. They will need to know as early as possible that your student has special needs that need to be taken into consideration when creating their schedule.
- Go to the Willowbrook Guidance Department (you do not need an appointment) and tell them you need to withdraw your special education student. You will need to fill out a withdraw form and sign a release of records giving Willowbrook permission to share their school records with your student's new school.
- Go to the Willowbrook Guidance Department and tell them you need to enroll your student.
(you do not need an appointment) Please bring a copy of your student's latest IEP and last three year re-evaluation paperwork. You can get a copy from their last school. We suggest you get this copy to cut down on the time it may take for the old school to send the paperwork. Willowbrook special education staff will need to review this paperwork to properly place your student and create their schedule. At this time, you will also schedule an appointment for your students to take the appropriate entrance exams.
- At the Guidance Department you will fill out several pieces of paperwork with demographic information. Additionally, please bring the documents listed below to prove residency within D88 and Willowbrook boundaries.
Illinois State law governs the process by which schools consider a student eligible to need a Special Education evaluation. The full explanation for this eligibility is individualized by student need, disability and demonstrated progress in school. If you would like to request a Special Education Evaluation, please put your request in writing and send to Nick Hildreth, Special Education Department Chair at nhildreth@dupage88.net or send to Willowbrook at 1250 S. Ardmore Avenue, Villa Park IL 60181 c/o Nick Hildreth. Mr. Hildreth will get back to you on the individualized process for your student.
Special Education records are considered a "temporary" record for a student. Law requires that schools keep a student's temporary record for five years after their graduation and then shred the documents. We do house a student's special education records for five years; however, if you are requiring some type of documentation prior to that year we are not able to supply that information. We are able to provide basic information for people on a case by case basis. Only previous students themselves or the legal guardian for a person over the age of 18 is able to request records. Please contact Shelley Kanara, Special Education Department Secretary, at 630-530-3431 to request the information. She will consult with Nick Hildreth, Special Education Department Chair, to see what information is appropriate to provide. We will need a first and last name at the time of graduation, year of graduation, date of birth and a phone number to return the call.
At Willowbrook High School we field a large number of requests for college students requiring observation hours within our programs. As a result, we create an observation schedule for students to follow when they come into the building. This schedule provides an experience in a wide variety of settings where an observer can obtain a perspective in working with a wide variety of students. If you would like to schedule dates to come in and follow this schedule, please call Nick Hildreth, Special Education Department Chair, at 630-530-3682 or email at nhildreth@dupage88.net.
If your college or university would like to request a placement at Willowbrook for a Practicum or Student Teaching placement, please send the information to Assistant Principal, Jamie Gourley at jgourley@dupage88.net or 630-530-3442. Ms. Gourley's office screens candidates and then will forward potential student teachers to the Department Chair. All student teaching applicants must apply to open vacancies online through our Human Resources department. Closing dates for fall and spring semester and listed there.
There are a variety of extra-curricular activities offered included a variety of sports and clubs. The participation of students with disabilities in these activities is encouraged. If your student is interested in pursuing involvement in any of these activities, please either discuss at their next IEP meeting or contact the Special Education Department Chair. Specifics on each of these activities are also available in the main office by contacting Assistant Principal Bob Daly or Athletic Director Brandon Murphy. Participation in a specific activity is discussed on a case by case basis. Below are a few activities that have been designed specifically to encourage same aged peer social and recreational opportunities.
Special Olympics Volleyball: The Willowbrook Special Olympics team competes with other volleyball teams from surrounding schools. The volleyball team practices in the fall season, and is coached by Ms. Tiffany Lamberty. She may be reached at tlamberty@dupage88.net.
Special Olympics Basketball: The Willowbrook Special Olympics team competes with local basketball teams. The team practices on Saturdays November through March. The Special Olympics basketball coaches are Tara Murphy and Tiffany Lamberty. They can be reached at tmurphy@dupage88.net, or tlamberty@dupage88.net.
Special Olympics Track and Field: The track and field team competes in the spring season, and is coached by Ms. Tiffany Lamberty. She may be reached at tlamberty@dupage88.net.
Best Buddies: Best Buddies pairs students with special needs with non-disabled peers. The goal of the program is to provide increased opportunities for socialization and school involvement. Best Buddies meets once a month. The sponsor of the Best Buddies program is Tiffany Lamberty. She can be reached at tlamberty@dupage88.net.
Social Network: The goal of this club is to provide a framework for students on the autism spectrum, or with social integration needs, to practice targeted social skills within the natural environment. Activities have included attending football games, plays/musicals etc… on campus with same aged peer models. The sponsors of the Social Network are Susan Moran and Erik Engel. They can be reached at smoran@dupage88.net, or eengel@dupage88.net.
All Special Education students receive direct case management services from a certified special educator Tuesday to Friday during their Warrior Time in their schedule after third period. This designated 35 minutes daily is for your student's case manager to progress monitor their progress and demonstrated skill in all of their classes. The case manager is your and your student's "go to" adult in the building. The case manager will also be at your student's annual review each year and provide you with nine week goal updates throughout the year. Each year the case manager will contact you to introduce themselves and provide you with their contact information. The programs below illustrate the level of service within the classes your student will receive which are determined at their annual review.
For any questions related to Special Education programming, please contact Mr. Nick Hildreth at numbers listed above.


I think I might like these, anybody have comments?
Any other brands a favorite?
Rotosound makes this fat honkin 115s in that style.
Back in the day we called the black La Bellas 'elephant hairs'.
Thought 115 was heavy as they got. Gonna be some serious tension on long scale!
115 is the heaviest, lots of sets are @ 100...even a few @ 95.
I have black tape strings on a Yamaha fretless.
It came with Dean Markley Blue Steel Roundwounds, Medium Light, 105-80-65-45.
My E String tone is a bit hollow to my ears, might just be an "off" string. The others are all very true and full.
The Rotos are heavier all the way up. I'm tempted to use the 5-string set, foregoing the G...tuning B E A D.
I love black tapes. That is all. But then I like for the bass to make LOW notes. I hate that slappy modern "bucket a beans" bass tone.
Black tape strings are great for "feel it in your gut" bass.
I went Shopping today locally, no luck, I'll buy online tonight.
Strings on order, and I corrected my "hollow" sounding E String...turns out my slot was a bit undersized, string riding high versus fully nested.
I am surprised I hadn't noticed, but with all the ReLo stuff since it arrived, and expecting everything to be fine otherwise on a new instrument, it slipped past me.
I'll need to make a new nut for the Black Tapes...maybe two.
I've got a set on a Squier Vista Musicmaster Bass and I love the sound and feel of them.
I've been using LaBella tapes for a few years. Round wounds, while having the sound I like, tear my fingers to shreds. I used stainless flats for a while, but they were too dull. A friend gave me a set of tapes and I'll never go back to regular flats. I've installed and played around with a few sets from Fender as well that were pretty solid.
My LaBellas are almost 4 years old on a Peavey P bass, and still sound bright and punchy.
Black Tapes on after two new nuts made. One for B-E-A-D, the other E-A-D-G.
Much more the Bass sound I prefer compared to Light Gauge Roundwounds as delivered.
The Low B is a curious thing, it will take my imagination some time to fully utilize.
Keeps the Ball End wrap off the Saddles, keeps the Low E outer wrap off the Tuning Peg.
Much improved tone off the Low E.
These are RotoSound Tru Bass 88's Black Tape.


Our hostel is looking for a fun, friendly and trustworthy team member to help out around the hostel. We have a chilled friendly vibe as we're not a party hostel. We do have a small rooftop bar giving out a free beer/soft drink every night between 7-7:30pm. Duties will include running the bar, chatting to guests & making sure people are having a good time.
Help hours are 6-11pm 5 days a week. Minimum stay required is 2 weeks. You will be provided with 1 bed in a 6 bed dorm room & a drinks allowance of 100.000vnd per day. The hostel is centrally located, a 5 minute walk to the backpacker bar/restaurant street. There are also lots of local foods in the surrounding area. If interested please get in touch.