NONAQUEOUS ELECTROLYTE SECONDARY BATTERY

• Main Author: IWASE KOSUKE
• Format: Patent
• Language: English; Japanese
• Published: 20.04.2015
• Subjects: BASIC ELECTRIC ELEMENTS; ELECTRICITY; PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSIONOF CHEMICAL INTO ELECTRICAL ENERGY

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery which is hard to cause an internal short circuit owing to a foreign material penetrating into a battery, and superior in reliability and durability.SOLUTION: The present invention provides a nonaqueous electrolyte secondary battery which comprises: an electrode body arranged by laminating a positive electrode, a separator 40 and a negative electrode 20 in turn; and a nonaqueous electrolyte. The separator 40 includes: a separator base 42 made of a resin; and a porous heat-resistant layer 30A including an inorganic filler, and formed on a surface of the base on the side opposed to the positive electrode. The negative electrode 20 has a porous heat-resistant layer 30B including an inorganic filler on its surface on the side opposed to the separator 40. As to the porous heat-resistant layers 30A and 30B, (1) the average thickness Tof the porous heat-resistant layer 30A is larger than the average thickness Tof the porous heat-resistant layer 30B; and (2) the average particle diameter Dof the inorganic filler included in the porous heat-resistant layer 30A is larger than the average particle diameter Dof the inorganic filler included in the porous heat-resistant layer 30B. 【課題】電池内に混入した異物に起因する内部短絡が生じ難く、信頼性や耐久性に優れた非水電解質二次電池を提供すること。【解決手段】本発明により、正極とセパレータ４０と負極２０とが順に積層された電極体と、非水電解質と、を備えた非水電解質二次電池が提供される。セパレータ４０は、樹脂製のセパレータ基材４２と、無機フィラーを含む多孔質耐熱層３０Ａであって上記基材の正極に対向する側の表面に形成された多孔質耐熱層３０Ａと、を備える。負極２０は、セパレータ４０に対向する側の表面に無機フィラーを含む多孔質耐熱層３０Ｂを備える。そして、上記多孔質耐熱層Ａ，Ｂは、（１）多孔質耐熱層Ａの平均厚みＴａが多孔質耐熱層Ｂの平均厚みＴｂより大きい；（２）多孔質耐熱層Ａに含まれる無機フィラーの平均粒径Ｄａが多孔質耐熱層Ｂに含まれる無機フィラーの平均粒径Ｄｂより大きい；を具備する。【選択図】図１