NONAQUEOUS ELECTROLYTE SECONDARY BATTERY

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery capable of efficiently exhausting gas to the outside of a battery case without blocking a gas flow path inside the battery case even when a battery is abnormally used.SOLUTION: An upper insulation plate having a through hole is arranged between an electrode group and a sealing plate. The upper insulation plate has a curved shape, and is arranged to be curved in a direction of the electrode group. By such a constitution, strength near a center part, at which a pressure of gas is concentrated during an abnormal time, can be improved. Therefore, movement of the electrode group can be restrained, and the gas can be efficiently exhausted to the outside of the battery case without blocking a gas flow path inside the battery case, so as to improve safety of a battery.