CYLINDRICAL NONAQUEOUS ELECTROLYTE SECONDARY BATTERY

摘要

PROBLEM TO BE SOLVED: To provide a cylindrical nonaqueous electrolyte secondary battery having excellent charge and discharge cycle characteristics in which the occurrence of internal short circuit is suppressed by using an isolation layer including cellulose.SOLUTION: The cylindrical nonaqueous electrolyte secondary battery comprises a pair of electrodes 5, 6 and a group of electrodes wound by a laminate including an isolation layer 7 arranged between the pair of electrodes. The isolation layer 7 includes a first layer 7a including cellulose and a second layer 7b including ceramic particles and a resin binding agent. If it is assumed that a distance from the winding axis of the group of electrodes to the outermost circumference is R in a surface perpendicular to the winding axis of the group of electrodes, a ratio (t/t) of a thickness (t) of the second layer to a thickness (t) of the first layer becomes smaller from the inner circumferential side of the group of electrodes toward the outer circumferential side at least in a region where the radius of curvature is not more than 0.3×R. A ratio (T/T) of a thickness (T) of the isolation layer of the innermost circumferential part of the group of electrodes to a thickness (T) of the isolation layer of the outermost circumferential part of the group of electrodes is not less than 0.90 and not more than 1.10.