Block Copolymer Solid Battery Electrolyte with High Li-Ion Transference Number

The electrochemical properties of a solid polymer electrolyte consisting of a diblock copolymer and lithium bis oxalato borate, LiBC4O8 LiBOB salt, is reported. The spherical microphase-separated diblock copolymer is composed of a majority poly ethylene oxide PEO block and a minority random copolymer block of methyl methacrylate MMA and lithium salt of methacrylic acid MAALi , PEO-bPMMA-ran-PMAALi . Salt-optimized electrolyte membranes of the diblock copolymer and LiBOB salt exhibited an average lithium-ion transference number TLi+ value of 0.9 at room temperature 21–23°C . The solid-state flexible, translucent polymer electrolyte shows a wide electrochemical stability window and excellent interface properties with the lithium metal electrode. The combination of these properties makes these block copolymer membranes viable electrolyte candidates for flexible lithium-ion batteries. © 2010 The Electrochemical Society. DOI: 10.1149/1.3428710 All rights reserved.