A hybrid supercapacitor, including at least one negative electrode that includes a statically capacitive active material, an electrochemical redox active material, or a mixture thereof, at least one positive electrode that includes a statically capacitive active material, an electrochemical redox active material, or a mixture thereof, at least one separator that is situated between the at least one negative electrode and the at least one positive electrode, and an electrolyte composition, with the condition that at least one electrode includes a statically capacitive active material, and at least one electrode includes an electrochemical redox active material, the electrolyte composition being a liquid electrolyte composition and including at least one liquid, aprotic, organic solvent, at least one conducting salt, and at least one additive.

A hybrid supercapacitor, including at least one negative electrode that includes a statically capacitive active material, an electrochemical redox active material, or a mixture thereof, at least one positive electrode that includes a statically capacitive active material, an electrochemical redox active material, or a mixture thereof, at least one separator that is situated between the at least one negative electrode and the at least one positive electrode, and an electrolyte composition, with the condition that at least one electrode includes a statically capacitive active material, and at least one electrode includes an electrochemical redox active material, the electrolyte composition being a liquid electrolyte composition and including at least one liquid, aprotic, organic solvent, at least one conducting salt, and at least one additive.

A hybrid supercapacitor, including at least one negative electrode having a statically capacitive active material, an electrochemical redox-active material, or a mixture of them; at least one positive electrode having a statically capacitive active material, an electrochemical redox-active material, or a mixture of them; at least one separator situated between the at least one negative electrode and the at least one positive electrode; and an electrolyte mixture; with the provision that at least one electrode includes a statically capacitive active material, and at least one electrode includes an electrochemical, redox-active material; the electrolyte mixture being a liquid electrolyte mixture and including at least one liquid, aprotic, organic solvent, at least one conducting salt, and at least one at least partially halogenated, aromatic compound.

A hybrid supercapacitor, including at least one negative electrode having a statically capacitive active material, an electrochemical redox-active material, or a mixture of them; at least one positive electrode having a statically capacitive active material, an electrochemical redox-active material, or a mixture of them; at least one separator situated between the at least one negative electrode and the at least one positive electrode; and an electrolyte mixture; with the provision that at least one electrode includes a statically capacitive active material, and at least one electrode includes an electrochemical, redox-active material; the electrolyte mixture being a liquid electrolyte mixture and including at least one liquid, aprotic, organic solvent, at least one conducting salt, and at least one at least partially halogenated, aromatic compound.

An electrolyte includes a lithium salt dissolved in a solvent mixture. The solvent mixture may include a first solvent component including an organic solvent having no carbonate groups; a second solvent component configured to improve the electrochemical properties of the first solvent at low temperatures; a third solvent compound configured to promote formation of a passivating SEI layer between the electrolyte and an electrode layer; and a fourth solvent compound configured to stabilize a lithium salt at high temperatures.

An electrolyte includes a lithium salt dissolved in a solvent mixture. The solvent mixture may include a first solvent component including an organic solvent having no carbonate groups; a second solvent component configured to improve the electrochemical properties of the first solvent at low temperatures; a third solvent compound configured to promote formation of a passivating SEI layer between the electrolyte and an electrode layer; and a fourth solvent compound configured to stabilize a lithium salt at high temperatures.

A lithium ion capacitor has an electrolytic solution that contains: 100 parts by volume of a solvent containing 20 to 50 parts by volume of propylene carbonate, 10 to 35 parts by volume of dimethyl carbonate, and 15 to 70 parts by volume of ethyl methyl carbonate; and lithium bis(fluorosulfonyl)imide, as an electrolyte. The lithium ion capacitor can maintain its initial high capacitance and low internal resistance, while also undergoing minimal characteristics changes in a low-temperature environment, even after exposure to a high-temperature, high-voltage environment.

A lithium ion capacitor has an electrolytic solution that contains: 100 parts by volume of a solvent containing 20 to 50 parts by volume of propylene carbonate, 10 to 35 parts by volume of dimethyl carbonate, and 15 to 70 parts by volume of ethyl methyl carbonate; and lithium bis(fluorosulfonyl)imide, as an electrolyte. The lithium ion capacitor can maintain its initial high capacitance and low internal resistance, while also undergoing minimal characteristics changes in a low-temperature environment, even after exposure to a high-temperature, high-voltage environment.

A lithium ion capacitor has an electrolytic solution that contains: an electrolyte which is a mixture of LiFSI and LiBF.sub.4, where the mol ratio of LiFSI to LiBF.sub.4 is in a range of 90/10 to 30/70; a solvent that contains at least one type of cyclic or chained carbonate compound; and a film-forming agent; wherein the concentration of electrolyte in the electrolytic solution is in a range of 1.2 to 1.8 mol/L. The lithium ion capacitor can maintain its initial high capacitance and low internal resistance, while also undergoing minimal characteristics changes after exposure to a high-temperature, high-voltage environment.

A lithium ion capacitor has an electrolytic solution that contains: an electrolyte which is a mixture of LiFSI and LiBF.sub.4, where the mol ratio of LiFSI to LiBF.sub.4 is in a range of 90/10 to 30/70; a solvent that contains at least one type of cyclic or chained carbonate compound; and a film-forming agent; wherein the concentration of electrolyte in the electrolytic solution is in a range of 1.2 to 1.8 mol/L. The lithium ion capacitor can maintain its initial high capacitance and low internal resistance, while also undergoing minimal characteristics changes after exposure to a high-temperature, high-voltage environment.