An enhanced electrochemical and cycling properties of novel boronic Ionic liquid based ternary gel polymer electrolytes for rechargeable Li/LiCoO2 cells

Abstract

A new generation of boronic ionic liquid namely 1-ethyl-3-methylimidazolium difluoro(oxalate) borate (EMImDFOB) was synthesized by metathesis reaction between 1-ethyl-3-methylimiazolium bromide and lithium difluoro(oxalate) borate (LiDFOB). Ternary gel polymer electrolyte membranes were prepared using electrolyte mixture EMImDFOB/LiDFOB with poly vinylidenefluoride-cohexafluoropropylene (PVdF-co-HFP) as a host matrix by facile solvent-casting method and plausibly demonstrated its feasibility to use in lithium ion batteries. Amongst ternary gel electrolyte membrane, DFOB-GPE3, which contained 80 wt% of EMImDFOB/LiDFOB and 20 wt% PVdF-co-HFP, showed excellent electrochemical and cycling behaviors. The highest ionic conductivity was found to be 10-3 Scm(-1) at 378 K. Charge-discharge profile of Li/DFOB-GPE3/LiCoO2 coin cell displayed a maximum discharge capacity of 148.4 mAhg(-1) at C/10 rate with impressive capacity retention capability and columbic efficiency at 298 K.