Abstract: Provided is a lithium ion secondary battery including a positive electrode which is capable of storing and releasing lithium, a negative electrode which is capable of storing and releasing lithium, and a nonaqueous electrolyte which contains lithium salts and cyclic disulfonic acid ester, in which as the nonaqueous electrolyte, a nonaqueous electrolyte containing a polymer is used, and as at least a part of the lithium salts, imide lithium salts are used. Here, the content of the cyclic sulfonic acid ester is preferably in a range of 2.0% to 5.0% by mass with respect to a total content of the nonaqueous electrolyte. Also, the proportion of the imide lithium salts is preferably in a range of 10 to 50 mol % with respect to a total amount of lithium salts in the nonaqueous electrolyte.

Abstract: Disclosed herein is a lithium secondary battery that includes an electrode assembly having a weight energy density of 250 Wh/Kg or more, and a heat exhaust layer provided on a surface of the electrode assembly. The electrode assembly has a structure in which a positive electrode and a negative electrode are alternately stacked through a separator. The positive electrode includes a positive electrode current collector and a positive electrode active material layer formed on a surface of the positive electrode current collector. The negative electrode including a negative electrode current collector and a negative electrode active material layer formed on a surface of the negative electrode current collector.

Abstract: In a lithium ion secondary battery including a positive electrode including a positive electrode active material containing a lithium nickel complex oxide, a cyclic sulfonic acid ester (al) which contains at least two sulfonyl groups in a molecule and a compound (a2) which contains only one sulfonyl group in a molecule and of which an energy level of a highest occupied molecular orbital calculated by a PM3 method is ?11.2 eV or less are used in an electrolyte. In addition, by charging such a battery, a film including a sulfur atom is formed on at least a portion of a surface of the positive electrode active material.

Abstract: Provided is a lithium ion secondary battery including a positive electrode which is capable of storing and releasing lithium, a negative electrode which is capable of storing and releasing lithium, and a nonaqueous electrolyte which contains lithium salts and cyclic disulfonic acid ester, in which as the nonaqueous electrolyte, a nonaqueous electrolyte containing a polymer is used, and as at least a part of the lithium salts, imide lithium salts are used. Here, the content of the cyclic sulfonic acid ester is preferably in a range of 2.0% to 5.0% by mass with respect to a total content of the nonaqueous electrolyte. Also, the proportion of the imide lithium salts is preferably in a range of 10 to 50 mol % with respect to a total amount of lithium salts in the nonaqueous electrolyte.