A metal foil including on at least one of its sides a layer of a material including: a metal or a metal alloy, carbon, hydrogen, and optionally oxygen, the atomic percentage of the metal or of the metals of the alloy in the material ranging from 10 to 60%, the atomic percentage of carbon in the material ranging from 35 to 70%, the atomic percentage of hydrogen in the material ranging from 2 to 20%, and the atomic percentage of oxygen if present in the material being less than or equal to 10%. The metal foil can be used in the manufacture of a cathode of a lithium-ion electrochemical cell. The deposition of this layer reduces the internal resistance of the cell.

A metal foil including on at least one of its sides a layer of a material including: a metal or a metal alloy, carbon, hydrogen, and optionally oxygen, the atomic percentage of the metal or of the metals of the alloy in the material ranging from 10 to 60%, the atomic percentage of carbon in the material ranging from 35 to 70%, the atomic percentage of hydrogen in the material ranging from 2 to 20%, and the atomic percentage of oxygen if present in the material being less than or equal to 10%. The metal foil can be used in the manufacture of a cathode of a lithium-ion electrochemical cell. The deposition of this layer reduces the internal resistance of the cell.

An electrochemical device, which is a non-aqueous electrochemical device, comprising a polymer (P) enclosed in an inside of the electrochemical device, wherein the polymer (P) is a polymer having a molecular structure containing a unit (P) represented by the following formula (P), the polymer (P) having a weight-average molecular weight of greater than 50,000, as well as an electrode for an electrochemical device, a coating liquid for an electrochemical device, an insulating layer for an electrochemical device, an undercoat layer for an electrochemical device, and an electrolytic solution for an electrochemical device including the polymer (P) and other ingredients:

##STR00001## in the formula (P), R.sup.P is a group of 1 to 20 carbon atoms.

A nonaqueous electrolyte secondary battery includes a positive electrode having a positive electrode mixture layer, a negative electrode, and a nonaqueous electrolyte, wherein the positive electrode mixture layer includes a positive electrode active material and inactive particles, the positive electrode active material includes a lithium-containing composite oxide, an average particle size D1 of the positive electrode active material and an average particle size D2 of the inactive particles satisfy D1>D2, and a viscosity at 30° C. of the nonaqueous electrolyte is less than 2 mPa.Math.s.

A secondary battery includes a positive electrode, a negative electrode, and an electrolytic solution. The positive electrode includes a positive electrode active material layer. The positive electrode active material layer includes a lithium-nickel composite oxide of a layered rock-salt type.

Provided is a battery including: a positive electrode containing a positive electrode active material; a negative electrode; and an electrolyte solution containing a nonaqueous solvent. The positive electrode active material contains a compound represented by composition formula (1) below and having a crystal structure belonging to space group FM3-M: Li.sub.xMe.sub.yO.sub.αF.sub.β. (1) Here, Me is one or two or more elements selected from the group consisting of Mn, Co, Ni, Fe, Al, B, Ce, Si, Zr, Nb, Pr, Ti, W, Ge, Mo, Sn, Bi, Cu, Mg, Ca, Ba, Sr, Y, Zn, Ga, Er, La, Sm, Yb, V, and C. x, y, α, and β satisfy the following conditions: 1.7≤x≤2.2, 0.8≤y≤1.3, 1≤α≤2.5, and 0.5≤β≤2, respectively. The nonaqueous solvent includes at least one solvent selected from hydrofluoroethers, phosphazenes, phosphates, and perfluoropolyethers.

Provided is a battery including: a positive electrode containing a positive electrode active material; a negative electrode; and an electrolyte solution containing a nonaqueous solvent. The positive electrode active material contains a compound represented by composition formula (1) below and having a crystal structure belonging to space group FM3-M: Li.sub.xMe.sub.yO.sub.αF.sub.β. (1) Here, Me is one or two or more elements selected from the group consisting of Mn, Co, Ni, Fe, Al, B, Ce, Si, Zr, Nb, Pr, Ti, W, Ge, Mo, Sn, Bi, Cu, Mg, Ca, Ba, Sr, Y, Zn, Ga, Er, La, Sm, Yb, V, and C. x, y, α, and β satisfy the following conditions: 1.7≤x≤2.2, 0.8≤y≤1.3, 1≤α≤2.5, and 0.5≤β≤2, respectively. The nonaqueous solvent includes at least one solvent selected from hydrofluoroethers, phosphazenes, phosphates, and perfluoropolyethers.

An electrolytic copper foil includes a raw foil layer having a first surface and a second surface opposite to the first surface. In the X-ray diffraction spectrum of the first surface, a ratio of the diffraction peak intensity I(200) of the (200) crystal face of the first surface relative to the diffraction peak intensity I(111) of the (111) crystal face of the first surface is between 0.5 and 2.0. In the X-ray diffraction spectrum of the second surface, a ratio of the diffraction peak intensity I(200) of the (200) crystal face of the second surface relative to the diffraction peak intensity I(111) of the (111) crystal face of the second surface is also between 0.5 and 2.0. A method for producing the electrolytic copper foil, and a lithium ion secondary battery is also provided.

A cylindrical secondary battery includes a bottomed cylindrical battery case having an opening, an electrode group, an electrolyte solution, and a sealing member blocking the opening of the battery case. The electrode group includes a positive electrode, a negative electrode, and a separator. The negative electrode includes a negative electrode current collector and a negative electrode mix layer placed on at least one principal surface of the negative electrode current collector. The negative electrode mix layer includes a non-facing region not facing the positive electrode mix layer. The density of the negative electrode mix layer is 1.25 g/cm.sup.3 to 1.43 g/cm.sup.3, the ratio of the entire length of the non-facing region to the entire length of the negative electrode mix layer is 0.09 or more, and the inside diameter of a hollow section of the electrode group is 2.0 mm or less.

A solid electrolyte interface is formed on a silicon monoxide electrode in a battery cell. While the solid electrolyte interface is being formed on the silicon monoxide electrode, the battery cell is charged for one or more initial cycles.