Abstract: Water-in-salt electrolytes for zinc metal batteries are disclosed. The electrolyte includes a zinc halide. The electrolyte may be a hybrid water-in-salt electrolyte further including an additional metal halide or nonmetal halide. Batteries including the electrolytes are disclosed, as well as devices including the batteries and methods of making the batteries.

Abstract: An metal composite cathode includes a composite of (i) a first component comprising one or more metal salts, wherein each metal salt is an alkali metal salt or an alkaline earth metal salt comprising M where M is Li, Na, K, Mg, Ca, or any combination thereof, (ii) a second component comprising a transition metal, a transition metal sulfide, a transition metal carbonate, a transition metal halide, or any combination thereof, and (iii) a carbon additive. The composite cathode may be used in a metal battery or metal ion battery.

Abstract: A rechargeable zinc metal battery cell includes a zinc metal anode, a cathode, a porous separator between them, and an electrolyte composition absorbed by the porous separator and in contact with both anode and cathode. The electrolyte composition includes (i) an aqueous solution of zinc chloride at a concentration greater than 15 molal, and (ii) dimethyl carbonate present at a mass ratio between 0.1:1.0 and 1.0:1.0 with respect to water in the aqueous solution. In some examples: the anode includes zinc metal foil stacked on titanium metal foil; the cathode includes vanadium(V) phosphate; the porous separator includes glass fibers and is less than 200 ?m thick; or the electrolyte composition includes (i) an aqueous solution of 30 molal zinc chloride, 5 molal lithium chloride, and 10 molal trimethyl ammonium chloride, and (ii) dimethyl carbonate present at a mass ratio of 1.0:1.0 with respect to water in the aqueous solution.

Abstract: Water-in-salt electrolytes for zinc metal batteries are disclosed. The electrolyte includes a zinc halide. The electrolyte may be a hybrid water-in-salt electrolyte further including an additional metal halide or nonmetal halide. Batteries including the electrolytes are disclosed, as well as devices including the batteries and methods of making the batteries.

Abstract: Electrolytes for use in electric double-layer capacitors (EDLCs; often referred as supercapacitors or ultracapacitors) are disclosed. In one example, the electrolyte comprises viologen in both the anolyte and the catholyte (with bromide). In another example, the electrolyte comprises viologen (in the anolyte) and tetraalkylammonium with bromide (in the catholyte), wherein the tetraalkylammonium is used to achieve solid complexation of bromine in the activated carbon of the cathode. In a third example, a zinc bromine/tetraalkylammonium supercapacitor/battery hybrid is disclosed. Also disclosed is a corrosion resistant bipolar pouch cell that can be used with the electrolyte embodiments described herein.

Abstract: An electrochemical device includes a cathode containing graphene-wrapped Li2S nanoparticles. The graphene-wrapped Li2S nanoparticles are prepared by a method including heating lithium metal, and a carbon-sulfur source or a carbon source and a sulfur source in a sealed container at a temperature to produce lithium vapors, and vapors of the carbon-sulfur source or vapors of the carbon source and vapors of the sulfur source; and cooling the sealed container to produce the graphene-wrapped Li2S nanoparticles.

Abstract: Electrolytes for use in electric double-layer capacitors (EDLCs; often referred as supercapacitors or ultracapacitors) are disclosed. In one example, the electrolyte comprises viologen in both the anolyte and the catholyte (with bromide). In another example, the electrolyte comprises viologen (in the anolyte) and tetraalkylammonium with bromide (in the catholyte), wherein the tetraalkylammonium is used to achieve solid complexation of bromine in the activated carbon of the cathode. In a third example, a zinc bromine/tetraalkylammonium supercapacitor/battery hybrid is disclosed. Also disclosed is a corrosion resistant bipolar pouch cell that can be used with the electrolyte embodiments described herein.

Abstract: A method is provided for fabricating a graphene-doped, carbohydrate-derived hard carbon (G-HC) composite material for alkali metal-ion batteries. The method provides graphene oxide (GO) dispersed in an aqueous solution. A carbohydrate is dissolved into the aqueous solution and subsequently the water is removed to create a precipitate. In one aspect, the carbohydrate is sucrose. The precipitate is dehydrated and exposed to a thermal treatment of less than 1200 degrees C. to carbonize the carbohydrate. The result is the formation of a graphene-doped, carbohydrate-derived hard carbon (G-HC) composite. Typically, the G-HC composite is made up of graphene in the range of 0.1 and 20% by weight (wt %), and HC in the range of 80 to 99.9 wt %. The G-HC composite has a specific surface area of less than 10 square meters per gram (m2/g). A G-HC composite suitable for use in alkali metal-ion batteries electrodes is also provided.

Abstract: An electrical double layer capacitor (EDLC) energy storage device is provided that includes at least two electrodes and a redox-enhanced electrolyte including two redox couples such that there is a different one of the redox couples for each of the electrodes. When charged, the charge is stored in Faradaic reactions with the at least two redox couples in the electrolyte and in a double-layer capacitance of a porous carbon material that comprises at least one of the electrodes, and a self-discharge of the energy storage device is mitigated by at least one of electrostatic attraction, adsorption, physisorption, and chemisorption of a redox couple onto the porous carbon material.

Abstract: An electrochemical device includes a cathode containing graphene-wrapped Li2S nanoparticles. The graphene-wrapped Li2S nanoparticles are prepared by a method including heating lithium metal, and a carbon-sulfur source or a carbon source and a sulfur source in a sealed container at a temperature to produce lithium vapors, and vapors of the carbon-sulfur source or vapors of the carbon source and vapors of the sulfur source; and cooling the sealed container to produce the graphene-wrapped Li2S nanoparticles.

Abstract: An electrical double layer capacitor (EDLC) energy storage device is provided that includes at least two electrodes and a redox-enhanced electrolyte including two redox couples such that there is a different one of the redox couples for each of the electrodes. When charged, the charge is stored in Faradaic reactions with the at least two redox couples in the electrolyte and in a double-layer capacitance of a porous carbon material that comprises at least one of the electrodes, and a self-discharge of the energy storage device is mitigated by at least one of electrostatic attraction, adsorption, physisorption, and chemisorption of a redox couple onto the porous carbon material.

Abstract: An electrical double layer capacitor (EDLC) energy storage device is provided that includes an electrolyte having an anionic catholyte and a cationic anolyte, a positively charged electrode, and a negative charged electrode, where negatively charged oxidized species in the anionic catholyte are electrostatically attracted to the positively charged electrode, where positively charged reduced species in the cationic anolyte are electrostatically attracted to the negatively charged electrode, where self-discharge of the EDLC energy storage device is prevented.

Abstract: A method is provided for fabricating a graphene-doped, carbohydrate-derived hard carbon (G-HC) composite material for alkali metal-ion batteries. The method provides graphene oxide (GO) dispersed in an aqueous solution. A carbohydrate is dissolved into the aqueous solution and subsequently the water is removed to create a precipitate. In one aspect, the carbohydrate is sucrose. The precipitate is dehydrated and exposed to a thermal treatment of less than 1200 degrees C. to carbonize the carbohydrate. The result is the formation of a graphene-doped, carbohydrate-derived hard carbon (G-HC) composite. Typically, the G-HC composite is made up of graphene in the range of 0.1 and 20% by weight (wt %), and HC in the range of 80 to 99.9 wt %. The G-HC composite has a specific surface area of less than 10 square meters per gram (m2/g). A G-HC composite suitable for use in alkali metal-ion batteries electrodes is also provided.

Abstract: An electrical double layer capacitor (EDLC) energy storage device is provided that includes an electrolyte having an anionic catholyte and a cationic anolyte, a positively charged electrode, and a negative charged electrode, where negatively charged oxidized species in the anionic catholyte are electrostatically attracted to the positively charged electrode, where positively charged reduced species in the cationic anolyte are electrostatically attracted to the negatively charged electrode, where self-discharge of the EDLC energy storage device is prevented.

Abstract: An electrode material having carbon and sulfur is provided. The carbon is in the form of a porous matrix having nanoporosity and the sulfur is sorbed into the nanoporosity of the carbon matrix. The carbon matrix can have a volume of nanoporosity between 10 and 99%. In addition, the sulfur can occupy between 5 to 99% of the nanoporosity. A portion of the carbon structure that is only partially filled with the sulfur remains vacant allowing electrolyte egress. In some instances, the nanoporosity has nanopores and nanochannels with an average diameter between 1 nanometer and 999 nanometers. The sulfur is sorbed into the nanoporosity using liquid transport or other mechanisms providing a material having intimate contact between the electronically conductive carbon structure and the electroactive sulfur.

Abstract: An electrode material having carbon and sulfur is provided. The carbon is in the form of a porous matrix having nanoporosity and the sulfur is sorbed into the nanoporosity of the carbon matrix. The carbon matrix can have a volume of nanoporosity between 10 and 99%. In addition, the sulfur can occupy between 5 to 99% of the nanoporosity. A portion of the carbon structure that is only partially filled with the sulfur remains vacant allowing electrolyte egress. In some instances, the nanoporosity has nanopores and nanochannels with an average diameter between 1 nanometer and 999 nanometers. The sulfur is sorbed into the nanoporosity using liquid transport or other mechanisms providing a material having intimate contact between the electronically conductive carbon structure and the electroactive sulfur.