Electrochemical and mechanical properties of polyolefin hard segment with polyethylene oxide conductive phase block copolymers

Abstract

A high lithium ion conductivity polymer electrolyte with excellent mechanical properties was developed in a polyolefin hard segment with a polyethylene oxide conducting phase block copolymer (OEO) and tetraethylene glycol dimethyl ether (G4) composite polymer with lithium bis(fluorosulfonyl)imide (LiFSI). The effect of the modulus of polymers on the ionic conductivity is generally controversial; high ion conducting polymer electrolyte typically exhibit poor mechanical properties. The composite polymer electrolytes developed in this study have ion conductivities in the range of 10−5 to 4×10−4Scm−1 and tensile strengths in the range of 1 to 12MPa at room temperature. 10OEO-1.4LiFSI-2.5G4, where OEO is based on ethylene oxide (EO) units, has ionic conductivity of 1.3×10−4Scm−1 and tensile strength of 5.1MPa at room temperature. The high G4 content composite of 10OEO-3.0LiFSI-4.0G4 has a high ion conductivity of 4.0×10−4Scm−1, but a low tensile strength of 1.0MPa at room temperature. The OEO-LiFSI-G4 composite polymer with high conductivity and high tensile strength is an attractive candidate for the electrolyte in lithium polymer batteries.