a dark brown prec1p1tate. The product was separated, washed several times with distilled water and ethanol, and dried at 80° C. for 12 h. The sample is graphene-supported MnO$_{2 }$ in a powder form, which was mixed in a liquid electrolyte to form a wet cathode active material mixture, which was coated onto a current collector (carbon-protected Al foil). 

## Example 17: Graphene-Enhanced Nano Silicon Fabricated from TEOS as an Anode Active Material of a Lithium-Ion Battery 

[0184] Dilute 1 wt.% N002-PS to 0.2 wt.% N002-PS by DI water, and place the diluted PS solution to the ultrasonic bath and ultrasonic process for 30 minutes. Gradually add TEOS (0.2 wt.% N002-PS:TEOS=5:2) while stirring the PS solution. Then, keep stirring for 24 hours to get a complete hydrolysis of TEOS. Dropwise add 10% NH$_{3}$ .H$_{2}$O till the formation of gel, and the gel can be called as TP gel. Grind the TP gel to tiny particles. Oven dries at 120° C. for 2 hours, at 150° C. for 4 hours. Mix the dried TP particles with Mg in a ratio of 10:7. Use 20 times amount of7 mm SS balls and ball mill under Argon protection, gradually increase the rotating speed to 250 rpm. Put certain amount of TPM powders in Nickel crucible and heat treatment at 680° C. Prepare certain amount of 2M HCl solution. Then gradually add heat treated TPM powders to the acid solution. Keep the reaction for 2-24 hours, and then put the turbid liquid to the ultrasonic bath and ultrasonic process for 1 hour. Pour out the suspension to the filtration system. Discard the bottom large particles. Use DI water to rinse three times. Dry the yellow paste and blend the yellow paste to powders. The as-prepared nano particle has a SSA value range of30 m $^{2}$/g to 200 m $^{2}$/g due to different graphene contents. 

[0185] A certain amount of the dried TPM particles was then put into a muffle furnace and calcined at 400° C.-600° C. for 2 hours under air purging to remove the carbon content from the nanocomposite, producing graphene-free yellow-color silicon nano powders. Both Si nano powder and graphene-wrapped Si nano particles were used as a high-capacity anode active material. 

## Example 18: Cobalt Oxide (Co$_{3}$O$_{4}$ ) Particulates as an Anode Active Material 

[0186] Although LiCoO$_{2 }$ is a cathode active material, Co$_{3}$O$_{4 }$ is an anode active material of a lithium-ion battery since LiCoO$_{2 }$ is at an electrochemical potential of approxi› mately +4.0 volts relative to Li/Li+ and Co$_{3}$O$_{4 }$ is at an electrochemical potential of approximately +0.8 volts rela› tive to Li/Li+. 

[0187] An appropriate amount of inorganic salts Co(NO$_{3}$ ) $_{2}$.6H$_{2}$O and, subsequently, ammonia solution (NH$_{3}$ .H$_{2}$O, 25 wt %) were slowly added into a GO suspension. The resulting precursor suspension was stirred for several hours under an argon flow to ensure a complete reaction. The obtained Co(OH)igraphene precursor suspension was divided into two portions. One portion was filtered and dried under vacuum at 70° C. to obtain a Co(OH)$_{2}$/graphene composite precursor. This precursor was calcined at 450° C. in air for 2 h to form the layered Co$_{3}$Oigraphene compos› ites, which are characterized by having Co$_{3}$O$_{4}$-coated graphene sheets overlapping one another. These Co$_{3}$O$_{4}$ - coated graphene sheets are another high-capacity anode active material. 

## Example 19: Graphene-Enhanced Tin Oxide Particulates as an Anode Active Material 

[0188] Tin oxide (SnO$_{2}$ ) nano particles, an anode active material, were obtained by the controlled hydrolysis of SnC1$_{4}$ .5H$_{2}$O with NaOH using the following procedure: SnC1$_{4}$ .5H$_{2}$O (0.95 g, 2.7 m-mol) and NaOH (0.212 g, 5.3 m-mol) were dissolved in 50 mL of distilled water each. The NaOH solution was added drop-wise under vigorous stirring to the tin chloride solution at a rate of 1 mL/min. This solution was homogenized by sonication for 5 min. Subse› quently, the resulting hydrosol was reacted with the GO dispersion for 3 hours. To this mixed solution, few drops of 0.1 M of H$_{2}$ SO$_{4 }$ were added to flocculate the product. The precipitated solid was collected by centrifugation, washed with water and ethanol, and dried in vacuum. The dried product was heat-treated at 400° C. for 2 h under Ar atmosphere. 

## Example 20: Preparation of Graphene-Supported MnO$_{2 }$ and NaMnO$_{2 }$ Cathode Active Material for Sodium-Ion Cells 

[0189] The MnO$_{2 }$ powder was synthesized by two meth› ods (each with or without the presence of graphene sheets). In one method, a 0.1 mol/L KMnO$_{4 }$ aqueous solution was prepared by dissolving potassium permanganate in deion› ized water. Meanwhile 13.32 g surfactant of high purity sodium bis(2-ethylhexyl) sulfosuccinate was added in 300 mL iso-octane ( oil) and stirred well to get an optically transparent solution. Then, 32.4 mL of 0.1 mol/L KMnO$_{4 }$ solution and selected amounts of GO solution were added in the solution, which was ultrasonicated for 30 min to prepare a dark brown precipitate. The product was separated, washed several times with distilled water and ethanol, and dried at 80° C. for 12 h. The sample is graphene-supported MnO$_{2 }$ in a powder form, which was dispersed in a liquid electrolyte to form a slurry and coated onto a surface of Al foil. 

[0190] Additionally, NaMnO$_{2 }$ and NaMnO$_{2}$/graphene composite were synthesized by ball-milling mixtures of Na$_{2}$CO$_{3 }$ and MnO$_{2 }$ (at a molar ratio of 1 :2), with or without graphene sheets, for 12 h followed by heating at 870° C. for 10 h. 

## Example 21: Preparation of Electrodes for Potassium Metal Cells 

[0191] A sheet of potassium-coated graphene film was used as the anode active material while a layer of PVDF› bonded reduced graphene oxide (RGO) sheets, supplied from Angstron Materials, Inc. (Dayton, Ohio), was used as the cathode active material. The electrolyte used was 3.0 M ofKClO$_{4 }$ salt dissolved in a mixture of propylene carbonate and DOL (1/1 ratio). Charge-discharge curves were obtained at several current densities (from 50 mA/g to 50 A/g), corresponding to different C rates, with the resulting energy density and power density data measured and calculated. 

## Example 22: Preparation and Electrochemical Testing of Various Electrochemical Cells 

[0192] For most of the anode and cathode active materials investigated, we prepared electrochemical cells ( e.g. alkali metal-ion cells or alkali metal cells) using both the presently invented method and the conventional method. 

