Effect of tris(methoxy diethylene glycol) borate on ionic conductivity and electrochemical stability of ethylene carbonate-based electrolyte

The effect of tris(methoxy diethylene glycol) borate (TMDGB) on the coordination structure between ethylene carbonate (EC) solvents with high permittivity and ClO4− anions has been investigated by using a Fourier transform infrared (FT-IR) spectroscopy. The results of FT-IR analyses manifested that the boron atom of TMDGB anion receptor forms the complex with ClO4− anions. Even though Lewis acid–base interaction between the TMDGB anion receptor and ClO4− anions in the electrolyte solution lead to the prominent enhancement of both the dissociation degree of lithium salts and the lithium ion transference number, the ionic conductivity of the EC-based electrolyte solution decreased due to the trap of ClO4− anions by introducing the TMDGB anion receptor.The electrochemical stability of gel polymer electrolyte based on semi-interpenetrating network (IPN) structure with tris(pentafluoro phenyl) borane (TPFPB) or TMDGB anion receptor was obviously improved.