Performance Enhancement of Poly (Vinyl Alcohol) Composite Polymer Electrolyte for Li-Ion Battery Through Salt Immersion Process

Abstract

Poly (vinyl alcohol) (PVA) composite membrane as separator-cum-electrolyte for li-ion battery was prepared via solution casting method. Hydrophilicity of PVA helped to substitute flammable, toxic solvents with deionised water. Lithium bis(oxalato) borate (LiBOB) electrolyte salt was incorporated in the membrane to form flexible self-standing membrane of composite polymer electrolyte (CPE). To further enhance the ionic conductivity, CPE membrane was immersed in 1M LiBOB salt dissolved in deionised water. Neat PVA membrane would have been dissolved instantly in any solution involving water; introduction of LiBOB electrolyte salt deprived the hydrogen bond which transform it into an insoluble CPE membrane. EIS measurement showed that salt immersion boosted the CPE membrane ionic conductivity by four orders of magnitude, from 4.77×10–7 S/cm to 1.93×10–3 S/cm at room temperature.