Abstract: An object of the invention is to obtain such a lithium secondary battery that has high safety and is small in increase of the resistance in a full charged state. Means for solution of the invention relates to a positive electrode material for a lithium secondary battery containing a positive electrode active substance and a fullerene compound, characterized in that the fullerene compound is present on a surface of the positive electrode active substance; improvement of a lithium secondary battery in safety by making a fullerene compound present on a surface of a positive electrode active substance to suppress electrolysis of an electrolyte solution on a surface of a positive electrode particularly upon float charging; and suppression of increase of the resistance upon storing in a full charged state by making a fullerene compound present on a surface of a positive electrode active substance.

Abstract: To improve an impregnation property of an electrolyte and the cycle characteristics, which have been a problem in the case of employing a casing having a variable shape. A lithium secondary cell comprising a casing having a variable shape, and a cell element having a positive electrode, a negative electrode and an electrolyte, sealed in the casing, wherein a compound represented by following formula (1) is contained in the lithium secondary cell: A1-X-A2??(1) (wherein X is a Group VI element in the periodic table, and A1 and A2 represent an aromatic group, provided that A1 and A2 may be the same or different, and may be connected each other to constitute a ring.

Abstract: To improve an impregnation property of an electrolyte and the cycle characteristics, which have been a problem in the case of employing a casing having a variable shape. A lithium secondary cell comprising a casing having a variable shape, and a cell element having a positive electrode, a negative electrode and an electrolyte, sealed in the casing, wherein a compound represented by following formula (1) is contained in the lithium secondary cell: A1-X-A2??(1) (wherein X is a Group VI element in the periodic table, and A1 and A2 represent an aromatic group, provided that A1 and A2 may be the same or different, and may be connected each other to constitute a ring.

Abstract: To increase safety against overcharging of a lithium secondary cell which uses a lithium-nickel compound oxide as a positive electrode active material. A lithium secondary cell comprises a casing (2,3) and a lithium secondary cell element (1) using a lithium-nickel compound oxide as a positive electrode active material, accommodated in the casing. The specific surface area of the lithium-nickel compound oxide is from 0.1 to 10 m2/g, and a surface area capacity ratio S/C, i.e. a ratio of a cell surface area S (cm2) to a cell capacity (mAh), is from 0.05 to 5.

Abstract: To improve an impregnation property of an electrolyte and the cycle characteristics, which have been a problem in the case of employing a casing having a variable shape.