The effects of anion structure of lithium salts on the properties of in-situ polymerized thermoplastic polyurethane electrolytes

Thermoplastic polyurethane (TPU) electrolytes with lithium salts were prepared by an in-situ polymerization method. Three different lithium salts were used to study the effects of the anion structure on the properties of polyurethane electrolytes: LiCl, LiClO(4), LiN(SO(2)CF(3))(2) (LITESI). The effects of the anion structure on monomer (PTMG) prior to polymerization and on the properties of TPU electrolytes post polymerization were investigated. The anion structure of lithium salt has a significant influence on the ionic conductivity, thermal stability and tensile property of TPU electrolytes. The TPU electrolytes with LiTESI demonstrated a high ionic conductivity up to 10(-5) S/cm at 300 K. The ionic conductivity of polyurethane electrolytes with lithium salts is in the order: LiCl < LiClO(4) < LiTESI. It was found that the lithium salts with larger anions were easily dissociated in TPU and had stronger interaction with TPU, which provided more charge carriers and gave higher ionic conductivity. (C) 2010 Elsevier Ltd. All rights reserved.