Secondary battery including separator containing electroconductive porous layer sandwiched between electroconductive material-free porous layers
First Claim
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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, andthe 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, andwherein 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.
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Abstract
Provided is a very safe secondary battery that can prevent the occurrence of battery abnormalities even when the internal battery temperature increases due to, for example, overcharging. A separator 70 in this secondary battery has a laminated structure that is provided with at least two porous layers 76A, 72, 76B, wherein one of these layers forms a porous electroconductive layer 72 in which an electroconductive material 74 is dispersed in the porous layer.
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7 Claims
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1. A secondary battery comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification