基于多孔高分子刷的坚韧全有机复合电解质助力长循环锂金属电池

Porous polymer brush-based robust all-organic composite electrolytes enable stable lithium metal batteries

基于固态电解质的高安全性和高能量密度锂金属电池有望成为下一代储能器件.然而,固态电解质在高离子电导率与优良机械性能之间难以兼得,严重阻碍了其实际应用.本文利用多孔高分子刷(刚性多孔超交联聚氯甲基苯乙烯纳米球(xPCMS)表面接枝聚甲基丙烯酸缩水甘油酯(PGMA),xPCMS-g-PGMA)作为纳米填料,将其与聚乙二醇二胺(DPEG)、聚乙二醇二缩水甘油醚(PEGDE)进行交联,并引入电解液塑化剂后成功获得了一类坚韧的全有机复合电解质(xPCMS-g-PGMA-AOCE).刚性多孔xPCMS骨架可以增强复合膜的机械强度并为锂离子传输提供充足通道;毛发状反应性PGMA侧链有利于xPCMS-g-PGMA与DPEG、PEGDE等锂离子传输连续相之间形成均匀的三维交联网络结构,可以进一步提高膜力学性能以及促进锂离子均匀、快速传输.因此,基于xPCMS-g-PGMA-AOCE组装的锂金属电池在1 C电流密度下首圈放电比容量高达155 mAh g^(-1),循环360圈后容量保持率为88%.

High-safety and high-energy-density lithium metal batteries with solid electrolytes show promise as nextgeneration energy storage devices.However,the conflicting demands for high ionic conductivity and mechanical robustness have severely hindered their practical application.Herein,a class of robust all-organic composite electrolyte(xPCMS-g-PGMA-AOCE)is developed by using porous polymer brushes(polyglycidyl methacrylate-grafted hypercrosslinked poly(4-chloromethylstyrene)nanosphere,xPCMS-g-PGMA)as nanofillers to undergo crosslinking with diaminopoly(ethylene glycol)(DPEG)and poly(ethylene glycol)diglycidyl ether(PEGDE),followed by introducing electrolyte as plasticizer.The porous xPCMS inner cores with rigid hypercrosslinked skeletons enable high mechanical strength and provide efficient ion diffusion pathways;the reactive hairy PGMA side chains are beneficial for uniform crosslinking of xPCMS-g-PGMA nanofillers with conductive PEGDE and DPEG,which can further enhance the mechanical strength and facilitate homogeneous Li+flux.As a result,the lithium metal battery assembled with xPCMS-g-PGMA-AOCE exhibits a high initial capacity of 155 mAh ^(g-1) and excellent capacity retention of 88% over 360 cycles at 1 C.