Provided are a nonaqueous electrolyte capable of providing a nonaqueous electrolyte energy storage device with reduced direct current resistance and an increased capacity retention ratio after charge-discharge cycles, a nonaqueous electrolyte energy storage device including such a nonaqueous electrolyte, and a method for producing such a nonaqueous electrolyte energy storage device. One mode of the present invention is a nonaqueous electrolyte for an energy storage device, containing an additive represented by the following Formula (1) or Formula (2). In Formula (1), R.sup.1 to R.sup.4 are each independently a hydrogen atom or a group represented by —NR.sup.a.sub.2, —OR.sup.a, —SR.sup.a, etc., with the proviso that at least one of R.sup.1 to R.sup.4 is a group represented by —OR.sup.a, —SR.sup.a, —COOR.sup.a, —COR.sup.a, —SO.sub.2R.sup.a, or —SO.sub.3R.sup.a. In Formula (2), R.sup.5 to R.sup.7 are each independently a hydrogen atom or a group represented by —NR.sup.b.sub.2, —OR.sup.b, or —SR.sup.b, with the proviso that at least one of R.sup.5 to R.sup.7 is a group represented by —SR.sup.b. ##STR00001##

Provided are a nonaqueous electrolyte capable of providing a nonaqueous electrolyte energy storage device with reduced direct current resistance and an increased capacity retention ratio after charge-discharge cycles, a nonaqueous electrolyte energy storage device including such a nonaqueous electrolyte, and a method for producing such a nonaqueous electrolyte energy storage device. One mode of the present invention is a nonaqueous electrolyte for an energy storage device, containing an additive represented by the following Formula (1) or Formula (2). In Formula (1), R.sup.1 to R.sup.4 are each independently a hydrogen atom or a group represented by —NR.sup.a.sub.2, —OR.sup.a, —SR.sup.a, etc., with the proviso that at least one of R.sup.1 to R.sup.4 is a group represented by —OR.sup.a, —SR.sup.a, —COOR.sup.a, —COR.sup.a, —SO.sub.2R.sup.a, or —SO.sub.3R.sup.a. In Formula (2), R.sup.5 to R.sup.7 are each independently a hydrogen atom or a group represented by —NR.sup.b.sub.2, —OR.sup.b, or —SR.sup.b, with the proviso that at least one of R.sup.5 to R.sup.7 is a group represented by —SR.sup.b. ##STR00001##

According to one embodiment of the present invention, a secondary battery that can be used at a wide range of temperatures and is less likely to be influenced by an environmental temperature is provided. Furthermore, a secondary battery with high safety is provided. An electrolyte obtained by mixing an acyclic ester having high temperature characteristics with a fluorinated carbonic ester at 5 vol. % or higher, preferably 20 vol. % or higher, is used for the purpose of reducing interface resistance between an electrode and an electrolyte, whereby a secondary battery capable of operating at a wide range of temperatures, specifically, at temperatures higher than or equal to −40° C. and lower than or equal to 150° C., preferably higher than or equal to −40° C. and lower than or equal to 85° C. can be achieved.

The invention provides electrolyte compositions including a metal cation, an ionic liquid, and a chelator that coordinates the metal cation. The electrolyte compositions are advantageous as they exhibit increased ion transference, and thus increased total conductivity, relative to a pure ionic liquid electrolyte that coordinates the metal cation. The invention provides a general strategy to control the cation-anion dynamics that govern ionic liquid performance. Electrolytes of the invention may be useful for any suitable purpose, e.g., in primary and secondary batteries, supercapacitors, and solar cells.

The invention provides electrolyte compositions including a metal cation, an ionic liquid, and a chelator that coordinates the metal cation. The electrolyte compositions are advantageous as they exhibit increased ion transference, and thus increased total conductivity, relative to a pure ionic liquid electrolyte that coordinates the metal cation. The invention provides a general strategy to control the cation-anion dynamics that govern ionic liquid performance. Electrolytes of the invention may be useful for any suitable purpose, e.g., in primary and secondary batteries, supercapacitors, and solar cells.

Electrolytes and electrolyte additives for energy storage devices comprising functional thiophene compounds are disclosed. The energy storage device comprises a first electrode and a second electrode, wherein at least one of the first electrode and the second electrode is a Si-based electrode, a separator between the first electrode and the second electrode, an electrolyte, and at least one electrolyte additive selected from a thiophene compound.

An ultracapacitor that is capable of exhibiting good properties even after being subjected to high temperatures, such as experienced during solder reflow, is provided. The ultracapacitor contains a housing having sidewalls that extend in a direction generally perpendicular to a base. An interior cavity is defined between an inner surface of the base and the sidewalls within which an electrode assembly can be positioned. To attach the electrode assembly, first and second conductive members are disposed on the inner surface of the base. The electrode assembly likewise contains first and second leads that extend outwardly therefrom and are electrically connected to the first and second conductive members, respectively. The first and second conductive members are, in turn, electrically connected to first and second external terminations, respectively, which are provided on an outer surface of the base.

An electrolytic solution is provided and includes an electrolytic solution for an electrochemical device including a magnesium electrode as a negative electrode and a positive electrode, the electrolytic solution containing: a solvent; and a first magnesium salt having a disilazide structure represented by General Formula (1):

(R.sub.3Si).sub.2N  (1) wherein R is an aliphatic hydrocarbon group having 1 or more and 10 or less carbon atoms, and each R may be the same as or different from each other, the electrolytic solution substantially comprising no halogen.

Provided is an electrochemical device including a negative electrode, a positive electrode, and a separator disposed between the negative electrode and the positive electrode. In the electrochemical device, the negative electrode is an electrode containing magnesium, and is in contact with a fullerene analogue-containing layer containing a fullerene analogue. The electrolytic solution of the electrochemical device includes a solvent and a magnesium salt contained in the solvent.

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.