Patent ID: 9660240
Date: 2017-05-23
CPC Classifications: H01M,Y02E

Claim:
1. A secondary battery comprising: a positive electrode; a negative electrode; and a porous separator interposed between the positive electrode and the negative electrode, wherein the separator has a porous electroconductive layer in which an electroconductive material is dispersed, and two electroconductive material-free porous layers laminated on opposite sides of the porous electroconductive layer, the melting point of a polymer constituting the porous electroconductive layer is lower than the melting point of a polymer constituting both of the two electroconductive material-free porous layers, an average particle diameter of the electroconductive material present in the porous electroconductive layer is not larger than an average pore diameter of both of the two electroconductive material-free porous layers, and the average pore diameter of both of the two electroconductive material-free porous layers is not larger than an average pore diameter of the porous electroconductive layer, and wherein the porous electroconductive layer and the two electroconductive material-free porous layers are configured such that a plurality of electroconductive pathways are formed, connecting the positive electrode to the negative electrode, when an internal temperature of the secondary battery increases due to overcharging.