An energy storage device according to an aspect of the present invention includes a negative electrode and a positive electrode, the negative electrode includes a negative substrate and a negative active material layer directly or indirectly layered on the negative substrate, the negative active material layer contains a negative active material, the negative active material contains solid graphite particles as a main component, the aspect ratio of the solid graphite particles is 1 or more and 5 or less, and a negative electrode utilization factor that is the proportion of the amount of charge per mass of the negative active material in a full charge state to a theoretical capacity per mass of graphite is 0.65 or more.

A positive electrode active material with high charge and discharge capacity is provided. A positive electrode active material with high charge and discharge voltage is provided. A secondary battery which hardly deteriorates is provided. A highly safe power storage device is provided. A novel secondary battery is provided. The positive electrode active material contains cobalt, oxygen, and fluorine and includes a bond of the cobalt and the fluorine in a surface portion or the vicinity of a grain boundary. By having the bond with fluorine, at least part of cobalt is high-spin (paramagnetic) Co.sup.2+. Thus, in ESR analysis, the spin concentration at 113 K is higher than the spin concentration at 300 K by 1.1×10.sup.−5 spins/g or more.

A scaffold includes struts that intersect at nodes. In some instances, a cross section of the cores has at least one dimension less than 100 microns. The core can be a solid, liquid or a gas. In some instances, one or more shell layers are positioned on the core.

A scaffold includes struts that intersect at nodes. In some instances, a cross section of the cores has at least one dimension less than 100 microns. The core can be a solid, liquid or a gas. In some instances, one or more shell layers are positioned on the core.

According to this method for producing an electrode, a fibrous binder is produced by fibrillating a particulate binder, which has a volume-based median diameter of from 5 to 100 .Math.m, by means of the application of a shear force, and an electrode mixture is produced by mixing the fibrous binder with an active material, said electrode mixture having a solid content concentration of substantially 100%. It is preferable that the fibrillation is carried out so that the breaking peripheral velocity ratio of the electrode mixture is 8 or more. In addition, an electrode mixture sheet is produced by shaping the electrode mixture into a sheet form by rolling, and the electrode mixture sheet is subsequently bonded to a core material.

An energy storage device according to one aspect of the present invention includes: an electrode assembly including a positive electrode, a negative electrode, and a separator; a nonaqueous electrolyte; and a case for housing the electrode assembly and the nonaqueous electrolyte, in which the positive electrode contains a positive active material, the positive active material contains a plurality of particles satisfying at least one of conditions (1) and (2) below, and the electrode assembly is in a pressed state. (1) A plurality of primary particles that do not form secondary particles (2) A plurality of secondary particles formed by aggregation of a plurality of primary particles, having a ratio of an average diameter of the secondary particles to an average diameter of the primary particles that form the secondary particles of less than 11

One aspect of the present invention is a nonaqueous electrolyte energy storage device including: a negative electrode containing a lithium alloy containing gold, and lithium metal; a positive electrode; and a nonaqueous electrolyte, in which the negative electrode includes a negative electrode substrate including a metal foil and a coating layer coating the negative electrode substrate, the metal foil contains copper, nickel, or stainless steel as a main component, and the coating layer contains gold as a main component.

A conductive composite material that includes: particles of a layered material including one or plural layers, wherein the one or plural layers include a layer body represented by: M.sub.mX.sub.n, where M is at least one metal of Group 3, 4, 5, 6, or 7, X is a carbon atom, a nitrogen atom, or a combination thereof, n is not less than 1 and not more than 4, m is more than n but not more than 5, and a modifier or terminal T exists on a surface of the layer body, where T is at least one of a hydroxyl group, a fluorine atom, a chlorine atom, an oxygen atom, or a hydrogen atom; and a polymer material that includes a hydrogen acceptor and a hydrogen donor, a ratio of the particles of the layered material is more than 19% by volume but not more than 95% by volume.

A binder for an electrochemical device made of a polymer material including a first polymer containing a first constituent unit having a guest group in a side chain; and a second polymer containing a second constituent unit having a host group in a side chain. Also disclosed is an electrode mixture containing the binder, an electrode active material and a dispersion medium; an electrode containing the binder, an electrode active material and a current collector; an electrochemical device including the electrode; and a secondary battery including the electrode.

Disclosed are an electrode having a three-dimensional structure, the electrode including: a porous nonwoven web including a plurality of polymer fibers that form an interconnected porous network; an active material composite positioned among the polymer fibers and including active material particles and a first conductive material; and a second conductive material positioned on an outer surface of the active material composite, wherein the interconnected porous network is filled homogeneously with the active material composite and the second conductive material to form a super lattice structure, and an electrochemical device including the electrode having a three-dimensional structure.