FLAT NONAQUEOUS SECONDARY BATTERY

摘要

A flat nonaqueous secondary battery with improved reliability is provided. The flat nonaqueous secondary battery (1) includes an electrode assembly disposed in a space formed by an exterior case (2) and a seal case (3). The electrode assembly includes a plurality of positive electrodes (5) and a plurality of negative electrodes (6) alternately stacked upon each other and a separator (7). The separator (7) has a joint (7c) formed by welding together at least a portion of its periphery. When the separator (7) and the positive electrode (5) are measured along a cross section in their thickness direction, the ratio A/B of the shortest distance A between the end of the joint (7c) of the separator (7) facing the positive electrode (5) and the outer periphery of the positive electrode (5) sandwiched by the separator (7) to the thickness B of the positive electrode (5) is not smaller than 1.