A storage device having excellent cycle lifetime, an electrode used in this storage device, and a production method of the electrode are provided. An electrode comprising an active material and a conductive carbon including oxidized carbon. A surface of the active material is covered by the conductive carbon. A Raman spectrum of the active material covered by the conductive carbon includes a peak intensity (a) derived from the active material and a peak intensity (b) of D-band derived from the conductive carbon. A peak intensity ratio (b)/(a) between the peak intensity (a) and the peak intensity (b) is 0.25 or more.

Electrically-conductive articles are provided that include a current collector having a conductive coating. The current collector has nanoporous structure, such as that from etched metal, and a carbon coating in contact with the current collector. The carbon coating is free of binder. In some embodiments, the current collector includes etched aluminum. The provided electrically-conductive articles can be electrochemical capacitors or lithium-ion electrochemical cells.

Electrically-conductive articles are provided that include a current collector having a conductive coating. The current collector has nanoporous structure, such as that from etched metal, and a carbon coating in contact with the current collector. The carbon coating is free of binder. In some embodiments, the current collector includes etched aluminum. The provided electrically-conductive articles can be electrochemical capacitors or lithium-ion electrochemical cells.

A porous silicon composite including: a porous silicon composite cluster comprising a porous silicon composite secondary particle and a second carbon flake on at least one surface of the porous silicon composite secondary particle; and a carbonaceous layer on the porous silicon composite cluster, the carbonaceous layer comprising amorphous carbon, wherein the porous silicon composite secondary particle comprises an aggregate of two or more silicon primary particles, the two or more silicon primary particles comprise silicon, a silicon suboxide of the formula SiO.sub.x, wherein 0<x<2 on a surface of the silicon, and a first carbon flake on at least one surface of the silicon suboxide, the silicon suboxide is in a form of a film, a matrix, or a combination thereof, and the first carbon flake and the second carbon flake are each independently present in a form of a film, particles, a matrix, or a combination thereof. Also a method of preparing the porous silicon composite, a carbon composite, an electrode, and a device, each including the porous silicon composite, and a lithium battery including the electrode.

A porous silicon composite including: a porous silicon composite cluster comprising a porous silicon composite secondary particle and a second carbon flake on at least one surface of the porous silicon composite secondary particle; and a carbonaceous layer on the porous silicon composite cluster, the carbonaceous layer comprising amorphous carbon, wherein the porous silicon composite secondary particle comprises an aggregate of two or more silicon primary particles, the two or more silicon primary particles comprise silicon, a silicon suboxide of the formula SiO.sub.x, wherein 0<x<2 on a surface of the silicon, and a first carbon flake on at least one surface of the silicon suboxide, the silicon suboxide is in a form of a film, a matrix, or a combination thereof, and the first carbon flake and the second carbon flake are each independently present in a form of a film, particles, a matrix, or a combination thereof. Also a method of preparing the porous silicon composite, a carbon composite, an electrode, and a device, each including the porous silicon composite, and a lithium battery including the electrode.

An electrochemical device includes a positive electrode, a negative electrode, and an electrolyte having lithium ion conductivity. The positive electrode includes a positive current collector and a positive electrode mixture layer supported on the positive current collector. The positive electrode mixture layer contains a positive electrode active material reversibly doped with an anion. The negative electrode includes a negative current collector and a negative electrode mixture layer supported on the negative current collector. The negative electrode mixture layer contains a negative electrode active material reversibly doped with lithium ions. The negative electrode active material contains non-graphitizable carbon. A ratio Mp/Mn of a mass Mp of the positive electrode active material supported on a unit area of the positive electrode to a mass Mn of the negative electrode active material supported on a unit area of the negative electrode is in a range from 1.1 to 2.5, inclusive.

An electrochemical device includes a positive electrode, a negative electrode, and an electrolyte having lithium ion conductivity. The positive electrode includes a positive current collector and a positive electrode mixture layer supported on the positive current collector. The positive electrode mixture layer contains a positive electrode active material reversibly doped with an anion. The negative electrode includes a negative current collector and a negative electrode mixture layer supported on the negative current collector. The negative electrode mixture layer contains a negative electrode active material reversibly doped with lithium ions. The negative electrode active material contains non-graphitizable carbon. A ratio Mp/Mn of a mass Mp of the positive electrode active material supported on a unit area of the positive electrode to a mass Mn of the negative electrode active material supported on a unit area of the negative electrode is in a range from 1.1 to 2.5, inclusive.

An electrode material of a supercapacitor includes a negative material prepared by the following steps: first dispersing graphite oxide in deionized water; after stirring and ultrasonic treatment, reducing the graphite oxide into reduced graphene oxide by using a hydrazine hydrate, and vacuum drying at 40-80° C.; dispersing the reduced graphene oxide in a DMF solution with 2,6-diaminoanthraquinone, and stirring and performing the ultrasonic treatment again; at 60-90° C., adding isoamyl nitrite, and reacting for 18-24 h; and washing reaction products with ethanol and deionized water for multiple times, and finally freeze drying to obtain a product.

An electrode material of a supercapacitor includes a negative material prepared by the following steps: first dispersing graphite oxide in deionized water; after stirring and ultrasonic treatment, reducing the graphite oxide into reduced graphene oxide by using a hydrazine hydrate, and vacuum drying at 40-80° C.; dispersing the reduced graphene oxide in a DMF solution with 2,6-diaminoanthraquinone, and stirring and performing the ultrasonic treatment again; at 60-90° C., adding isoamyl nitrite, and reacting for 18-24 h; and washing reaction products with ethanol and deionized water for multiple times, and finally freeze drying to obtain a product.

The nonaqueous electrolyte energy storage device according to an aspect of the present invention includes a negative electrode including graphite and graphitizable carbon, in which a ratio of a mass of the graphitizable carbon to a total mass of the graphite and the graphitizable carbon is less than 26% by mass, and a median diameter of the graphitizable carbon is smaller than a median diameter of the graphite.