amount of the liquid solvent is removed to increase the salt concentration above 2.5 M. The liquid solvent can be a mixture of two or more liquid solvents; one of the liquid solvents is more volatile than the other(s ), enabling removal of some of the solvent. 

[0139] Thus, in certain embodiments, the first liquid elec› trolyte contains an initial concentration, M$_{1}$ , of a metal salt dissolved in a liquid solvent prior to the sub-step of depos› iting a wet cathode active material mixture and step (A) includes a procedure of removing a portion of the liquid solvent after deposition of the wet mixture to increase the metal salt concentration to a final concentration, M$_{2}$ , wherein M$_{2}$>M$_{1}$ . 

[0140] In certain embodiments, the second liquid electro› lyte contains an initial concentration, M$_{3}$ , of a metal salt dissolved in a liquid solvent prior to depositing the wet anode active material mixture and step (B) includes a procedure of removing a portion of the liquid solvent after the depositing step to increase the metal salt concentration to a final concentration, M$_{4}$ , wherein M$_{4}$ >M$_{3}$ . 

[0141] In the case wherein only one of the electrodes (e.g. cathode) is a wet mixture electrode, the first liquid electro› lyte may contain an initial concentration, M$_{5}$ , of a metal salt dissolved in a liquid solvent prior to depositing the wet cathode active material mixture and step (A) includes a procedure of removing a portion of the liquid solvent after deposition to increase a metal salt concentration to a final concentration, M$_{6}$, wherein M$_{6}$>Ms- 

[0142] The ionic liquid is composed of ions only. Ionic liquids are low melting temperature salts that are in a molten or liquid state when above a desired temperature. For instance, a salt is considered as an ionic liquid if its melting point is below 100° C. If the melting temperature is equal to or lower than room temperature (25° C.), the salt is referred to as a room temperature ionic liquid (RTIL). The IL salts are characterized by weak interactions, due to the combination of a large cation and a charge-delocalized anion. This results in a low tendency to crystallize due to flexibility (anion) and asymmetry (cation). 

[0143] A typical and well-known ionic liquid is formed by the combination of a l-ethyl-3-methylimidazolium (EMI) cation and an N,N-bis(trifluoromethane)sulphonamide (TFSI) anion. This combination gives a fluid with an ionic conductivity comparable to many organic electrolyte solu› tions and a low decomposition propensity and low vapor pressure up to -300-400° C. This implies a generally low volatility and non-flammability and, hence, a much safer electrolyte for batteries. 

[0144] Ionic liquids are basically composed of organic ions that come in an essentially unlimited number of struc› tural variations owing to the preparation ease of a large variety of their components. Thus, various kinds of salts can be used to design the ionic liquid that has the desired properties for a given application. These include, among others, imidazolium, pyrrolidinium and quaternary ammo› nium salts as cations and bis(trifluoromethanesulphonyl) imide, bis(fluorosulphonyl)imide, and hexafluorophosphate as anions. Based on their compositions, ionic liquids come in different classes that basically include aprotic, protic and zwitterionic types, each one suitable for a specific applica› tion. 

[0145] Common cations of room temperature ionic liquids (RTILs) include, but not limited to, tetraalkylammonium, di-, tri-, and tetra-alkylimidazolium, alkylpyridinium, 

dialkyl-pyrrolidinium, dialkylpiperidinium, tetraalkylphos› phonium, and trialkylsulfonium. Common anions of RTILs include, but not limited to, BF$_{4}$ -, B(CN) 4 -, CH $_{3}$BF$_{3}$ -, CH2CHBF$_{3}$-, CF$_{3}$BF$_{3}$-, C$_{2}$F$_{5}$ BF$_{3}$-, n-C$_{3}$F$_{7}$BF$_{3}$-, n-C$_{4}$ F$_{9}$BF$_{3}$-, PF 6 -, CF $_{3}$CO$_{2}$ -, CF $_{3}$SO$_{3}$ -, N(SO $_{2}$CF$_{3}$ ) 2 -, N(COCF$_{3}$)(SO$_{2}$CF$_{3}$ t, N(SO$_{2}$F)$_{2}$-, N(CN)$_{2}$-, C(CN)$_{3}$-, SCN-, SeCN-, CuCl$_{2 }$ -, AlC1$_{4}$ -, F(HF)$_{23 }$ -, etc. Relatively speaking, the combination of imidazolium- or sulfonium› based cations and complex halide anions such as A1Cl$_{4}$ -, BF$_{4}$-, CF$_{3}$CO$_{2}$-, CF$_{3}$SO$_{3}$-, NTf 2 -, N(SO $_{2}$F)$_{2}$ -, orF(HF) 23 - results in RTILs with good working conductivities. 

[0146] RTILs can possess archetypical properties such as high intrinsic ionic conductivity, high thermal stability, low volatility, low (practically zero) vapor pressure, non-flam› mability, the ability to remain liquid at a wide range of temperatures above and below room temperature, high polarity, high viscosity, and wide electrochemical windows. These properties, except for the high viscosity, are desirable attributes when it comes to using an RTIL as an electrolyte ingredient (a salt and/or a solvent) in a supercapacitor. 

[0147] In the invented process, the first or second polymer gel electrolyte may contain an ion-conducting polymer. Preferably, the ion-conducting polymer is selected from poly(ethylene oxide) (PEO), polypropylene oxide (PPO), poly(acrylonitrile) (PAN), poly(methyl methacrylate) (PMMA), poly(vinylidene fluoride) (PVdF), poly bis› methoxy ethoxyethoxide-phosphazenex, polyvinyl chloride, polydimethylsiloxane, poly(vinylidene fluoride )-hexafluo› ropropylene (PVDF-HFP), a sulfonated derivative thereof, a sulfonated polymer, or a combination thereof. 

[0148] In certain embodiments, the ion-conducting poly› mer may be selected from the group consisting of poly (perfluoro sulfonic acid), sulfonated polytetrafluoroethyl› ene, sulfonated perfluoroalkoxy derivatives of polytetrafluoroethylene, sulfonated polysulfone, sulfonated poly( ether ketone), sulfonated poly ( ether ether ketone), sulfonated polystyrene, sulfonated polyimide, sulfonated styrene-butadiene copolymers, sulfonated poly chloro-trif› luoroethylene (PCTFE), sulfonated perfluoroethylene-pro› pylene copolymer (FEP), sulfonated ethylene-chlorotrifluo› roethylene copolymer (ECTFE), sulfonated polyvinylidenefluoride (PVDF), sulfonated copolymers of polyvinylidenefluoride with hexafluoropropene and tetra› fluoroethylene, sulfonated copolymers of ethylene and tet› rafluoroethylene (ETFE), sulfonated polybenzimidazole (PBI), their chemical derivatives, copolymers, blends and combinations thereof. 

[0149] In what follows, we provide examples for a large number of different types of anode active materials, cathode active materials, and conductive fillers to illustrate the best mode of practicing the instant invention. Theses illustrative examples and other portions of instant specification and drawings, separately or in combinations, are more than adequate to enable a person of ordinary skill in the art to practice the instant invention. However, these examples should not be construed as limiting the scope of instant invention. 

## Example 1: Preparation of Graphene Oxide (GO) and Reduced Graphene Oxide (RGO) Nano Sheets from Natural Graphite Powder 

[0150] Natural graphite from Huadong Graphite Co. (Qingdao, China) was used as the starting material. GO was obtained by following the well-known modified Hummers 

