A supercapacitor has a cathode and an anode. At least one of the cathode and the anode of the supercapacitor contains at least one material which stores polyvalent cations. Additionally, the supercapacitor also has an electrolyte. The electrolyte contains an electrolyte salt, and the electrolyte salt has at least one polyvalent cation.

Provided herein is a rechargeable power source that can be quickly charged and used for charging mobile and cordless devices. The power source includes an ultracapacitor which comprises a composite structure including, for example open graphene structures or graphene nanoribbons attached to an oxide layer. The oxide layer is on a metal foil surface. The oxide layer includes more than one metal atom.

Provided herein is a rechargeable power source that can be quickly charged and used for charging mobile and cordless devices. The power source includes an ultracapacitor which comprises a composite structure including, for example open graphene structures or graphene nanoribbons attached to an oxide layer. The oxide layer is on a metal foil surface. The oxide layer includes more than one metal atom.

Disclosed are a hybrid aluminum electrolytic capacitor and a method of producing the same. The preparation method includes impregnating a capacitive element in a fluid to improve the low-temperature property, where the fluid is prepared from a first organic solvent having a boiling point of 180° C. or more and a melting point of −50° C. or less, a small number of an inorganic or organic acid and an amine having a boiling point of 180° C. or more.

Disclosed are a hybrid aluminum electrolytic capacitor and a method of producing the same. The preparation method includes impregnating a capacitive element in a fluid to improve the low-temperature property, where the fluid is prepared from a first organic solvent having a boiling point of 180° C. or more and a melting point of −50° C. or less, a small number of an inorganic or organic acid and an amine having a boiling point of 180° C. or more.

Provided are a current collector which has an excellent high-rate property and exerts a sufficient safety function when employed in a secondary battery or a capacitor, as well as an electrode, a secondary battery or a capacitor in which said current collector is employed. According to the invention, a current collector is provided which comprises: metal foil; and a conductive layer with a film thickness of 0.1 μm to 10 μm formed on a surface of said metal foil. Here, said conductive layer includes a conductive material and a binder material. A melting point of said binder material is 80° C. to 150° C. Further, said binder material shows, in differential scanning calorimetry (DSC) in a range from room temperature to 200° C., one or more endothermic peaks in the heating-up process. In a case where said binder material shows two or more endothermic peaks, each difference between said peaks is 15° C. or more. Moreover, said binder material shows one or more exothermic peaks in the cooling-down process. In a case where said binder material shows only one exothermic peak, said exothermic peak falls within a range of 50 to 120° C., and a width at half maximum of said exothermic peak is 10° C. or less. On the other hand, in a case where said binder material shows two or more exothermic peaks, a maximum exothermic peak among said exothermic peaks falls within a range of 50 to 120° C., and a width at half maximum of said exothermic peak is 10° C. or less.

Provided are a current collector which has an excellent high-rate property and exerts a sufficient safety function when employed in a secondary battery or a capacitor, as well as an electrode, a secondary battery or a capacitor in which said current collector is employed. According to the invention, a current collector is provided which comprises: metal foil; and a conductive layer with a film thickness of 0.1 μm to 10 μm formed on a surface of said metal foil. Here, said conductive layer includes a conductive material and a binder material. A melting point of said binder material is 80° C. to 150° C. Further, said binder material shows, in differential scanning calorimetry (DSC) in a range from room temperature to 200° C., one or more endothermic peaks in the heating-up process. In a case where said binder material shows two or more endothermic peaks, each difference between said peaks is 15° C. or more. Moreover, said binder material shows one or more exothermic peaks in the cooling-down process. In a case where said binder material shows only one exothermic peak, said exothermic peak falls within a range of 50 to 120° C., and a width at half maximum of said exothermic peak is 10° C. or less. On the other hand, in a case where said binder material shows two or more exothermic peaks, a maximum exothermic peak among said exothermic peaks falls within a range of 50 to 120° C., and a width at half maximum of said exothermic peak is 10° C. or less.

Provided is an electrolyte salt comprising a quaternary ammonium cation indicated by formula (1) and a trimethylsilyl alkanesulfonate anion indicated by formula (2). ##STR00001##
(In the formula, R.sup.1-R.sup.4 each independently indicate a C1-4 alkyl group or an alkoxyalkyl group indicated by —(CH.sub.2).sub.n—OR. Any two among R.sup.1-R.sup.4 can mutually bond and form a ring together with a nitrogen atom to which same have bonded. The remaining two can mutually bond and form a spiro ring having a nitrogen atom as the spiro atom therefor. R indicates a methyl group or an ethyl group. n indicates 1 or 2 and m indicates 2 or 3.)

Provided is an electrolyte salt comprising a quaternary ammonium cation indicated by formula (1) and a trimethylsilyl alkanesulfonate anion indicated by formula (2). ##STR00001##
(In the formula, R.sup.1-R.sup.4 each independently indicate a C1-4 alkyl group or an alkoxyalkyl group indicated by —(CH.sub.2).sub.n—OR. Any two among R.sup.1-R.sup.4 can mutually bond and form a ring together with a nitrogen atom to which same have bonded. The remaining two can mutually bond and form a spiro ring having a nitrogen atom as the spiro atom therefor. R indicates a methyl group or an ethyl group. n indicates 1 or 2 and m indicates 2 or 3.)

This invention provides a multi-layer article comprising a first electrode material, a second electrode material, and a porous separator disposed between and in contact with the first and the second electrode materials, wherein the porous separator comprises a nonwoven consisting essentially of a plurality of fibers of a fully aromatic polyimide. Also provided is a method for preparing the multi-layer article, and an electrochemical cell employing the same. A multi-layer article comprising a polyimide nonwoven with enhanced properties is also provided.