Surface modification of polyolefin separators for lithium ion batteries to reduce thermal shrinkage without thickness increase  

作　　者：Peng Zhao Juping Yang Yuming Shang Li Wang Mou Fang Jianlong Wang Xiangming He 

机构地区：[1]Institute of Nuclear and New Energy Technology, Tsinghua University [2]Huadong Institute of Lithium Ion Battery [3]State Key Laboratory of Automotive Safety and Energy, Tsinghua University

出　　处：《Journal of Energy Chemistry》2015年第2期138-144,共7页能源化学（英文版）

基　　金：supported by the MOST(Grant No.2013CB934000,2014DFG71590,2011CB935902,2010DFA72760,2011CB711202,2013AA050903,2011AA11A257 and 2011AA11A254);China Postdoctoral Science Foundation(Grant No.2013M530599 and 2013M540929);Tsinghua University Initiative Scientific Research Program(Grant No.2010THZ08116,2011THZ08139,2011THZ01004 and 2012THZ08129);the State Key Laboratory of Automotive Safety and Energy(No.ZZ2012-011);Suzhou(Wujiang)Automotive Research Institute,Tsinghua University,Project No.2012WJ-A-01

摘　　要：Surface chemical modification of polyolefin separators for lithium ion batteries is attempted to reduce the thermal shrinkage, which is im- portant for the battery energy density. In this study, we grafted organic/inorganic hybrid crosslinked networks on the separators, simply by grafting polymerization and condensation reaction. The considerable silicon-oxygen crosslinked heat-resistance networks are responsible for the reduced thermal shrinkage. The strong chemical bonds between networks and separators promise enough mechanical support even at high temperature. The shrinkage at 150 ℃ for 30 min in the mechanical direction was 38.6% and 4.6% for the pristine and present graft-modified separators, respectively. Meanwhile, the grafting organic-inorganic hybrid crosslink networks mainly occupied part of void in the internal pores of the separators, so the thicknesses of the graft-modified separators were similar with the pristine one. The half cells prepared with the modified separators exhibited almost identical electrochemical properties to those with the commercial separators, thus proving that, in order to enhance the thermal stability of lithium ion battery, this kind of grafting-modified separators may be a better alternative to conventional silica nanoparticle layers-coated polyolefin separators.Surface chemical modification of polyolefin separators for lithium ion batteries is attempted to reduce the thermal shrinkage, which is im- portant for the battery energy density. In this study, we grafted organic/inorganic hybrid crosslinked networks on the separators, simply by grafting polymerization and condensation reaction. The considerable silicon-oxygen crosslinked heat-resistance networks are responsible for the reduced thermal shrinkage. The strong chemical bonds between networks and separators promise enough mechanical support even at high temperature. The shrinkage at 150 ℃ for 30 min in the mechanical direction was 38.6% and 4.6% for the pristine and present graft-modified separators, respectively. Meanwhile, the grafting organic-inorganic hybrid crosslink networks mainly occupied part of void in the internal pores of the separators, so the thicknesses of the graft-modified separators were similar with the pristine one. The half cells prepared with the modified separators exhibited almost identical electrochemical properties to those with the commercial separators, thus proving that, in order to enhance the thermal stability of lithium ion battery, this kind of grafting-modified separators may be a better alternative to conventional silica nanoparticle layers-coated polyolefin separators.

关 键 词：thermal shrinkage organic/inorganic hybrid crosslinked network chemical grafting SEPARATOR lithium ion battery 

分 类 号：TM912[电气工程—电力电子与电力传动] TQ317[化学工程—高聚物工业]