The present invention relates to an aqueous electrolyte capable of improving low temperature performance. More specifically, the present invention provides an aqueous electrolyte that is an aqueous solution including lithium trifluoromethanesulfonate at a predetermined concentration range without separate additives, and thus can prevent freezing and realize high performance even at a very low temperature of about −30° C. or less, and an energy storage device including the same.

A secondary battery includes a positive electrode, a negative electrode, and an electrolytic solution. The electrolytic solution includes a solvent, an electrolyte salt, a first unsaturated compound, and a second unsaturated compound. The first unsaturated compound includes at least one of respective compounds represented by Formulae (1) to (4). The second unsaturated compound includes at least one of respective compounds represented by Formulae (5) to (19).

A cap assembly is disclosed that creates a gas-tight seal with a cell can housing. The cap assembly has an outer surface, an inner surface and a perimeter edge. The cap assembly further includes an electrolyte injection port forming a port opening between the outer surface and the inner surface, a vent constructed to form a vent opening from the inner surface to the outer surface when a vent pressure differential is achieved between an outer surface pressure and an inner surface pressure. The vent is positioned (a) concentric to the electrolyte injection port, and (b) closer to the perimeter edge than the position of the electrolyte injection port.

A cap assembly is disclosed that creates a gas-tight seal with a cell can housing. The cap assembly has an outer surface, an inner surface and a perimeter edge. The cap assembly further includes an electrolyte injection port forming a port opening between the outer surface and the inner surface, a vent constructed to form a vent opening from the inner surface to the outer surface when a vent pressure differential is achieved between an outer surface pressure and an inner surface pressure. The vent is positioned (a) concentric to the electrolyte injection port, and (b) closer to the perimeter edge than the position of the electrolyte injection port.

A power system adapted for supplying power in a high temperature environment is disclosed. The power system includes a rechargeable energy storage that is operable in a temperature range of between about seventy degrees Celsius and about two hundred and fifty degrees Celsius coupled to a circuit for at least one of supplying power from the energy storage and charging the energy storage; wherein the energy storage is configured to store between about one one hundredth (0.01) of a joule and about one hundred megajoules of energy, and to provide peak power of between about one one hundredth (0.01) of a watt and about one hundred megawatts, for at least two charge-discharge cycles. Methods of use and fabrication are provided. Embodiments of additional features of the power supply are included.

A power system adapted for supplying power in a high temperature environment is disclosed. The power system includes a rechargeable energy storage that is operable in a temperature range of between about seventy degrees Celsius and about two hundred and fifty degrees Celsius coupled to a circuit for at least one of supplying power from the energy storage and charging the energy storage; wherein the energy storage is configured to store between about one one hundredth (0.01) of a joule and about one hundred megajoules of energy, and to provide peak power of between about one one hundredth (0.01) of a watt and about one hundred megawatts, for at least two charge-discharge cycles. Methods of use and fabrication are provided. Embodiments of additional features of the power supply are included.

An electrolyte solution for a potassium ion battery or a potassium ion capacitor, the electrolyte solution comprising at least one potassium salt compound selected from the group consisting of potassium bis(trifluoromethanesulfonyl)amide and potassium bis(fluorosulfonyl)amide and at least one solvent selected from the group consisting of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, pentaethylene glycol dimethyl ether, ethylene carbonate, and propylene carbonate, in which a concentration of the potassium salt compound in the electrolyte solution is from 1.5 mol/kg to 12.0 mol/kg.

An electrolyte solution for a potassium ion battery or a potassium ion capacitor, the electrolyte solution comprising at least one potassium salt compound selected from the group consisting of potassium bis(trifluoromethanesulfonyl)amide and potassium bis(fluorosulfonyl)amide and at least one solvent selected from the group consisting of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, pentaethylene glycol dimethyl ether, ethylene carbonate, and propylene carbonate, in which a concentration of the potassium salt compound in the electrolyte solution is from 1.5 mol/kg to 12.0 mol/kg.

An electrolyte solution for a potassium ion battery or a potassium ion capacitor, the electrolyte solution comprising at least one potassium salt compound selected from the group consisting of potassium bis(trifluoromethanesulfonyl)amide and potassium bis(fluorosulfonyl)amide and at least one solvent selected from the group consisting of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, pentaethylene glycol dimethyl ether, ethylene carbonate, and propylene carbonate, in which a concentration of the potassium salt compound in the electrolyte solution is from 1.5 mol/kg to 12.0 mol/kg.

An electrolyte solution for a potassium ion battery or a potassium ion capacitor, the electrolyte solution comprising at least one potassium salt compound selected from the group consisting of potassium bis(trifluoromethanesulfonyl)amide and potassium bis(fluorosulfonyl)amide and at least one solvent selected from the group consisting of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, pentaethylene glycol dimethyl ether, ethylene carbonate, and propylene carbonate, in which a concentration of the potassium salt compound in the electrolyte solution is from 1.5 mol/kg to 12.0 mol/kg.