Tailor-Made Electrospun Multilayer Composite Polymer Electrolytes for High-Performance Lithium Polymer Batteries

A novel tailor-made multilayer composite polymer electrolyte, consisting of two outer layers of electrospun polyacrylonitrile (PAN) and one inner layer of poly(vinyl acetate) (PVAc)/poly(methyl methacrylate) (PMMA)/poly(ethylene oxide) (PEO) fibrous membrane, was prepared using continuous electrospinning. These membranes, which are made up of fibers with diameters in the nanometer range, were stacked in layers to produce interconnected pores that result in a high porosity. Gel polymer electrolytes (GPEs) were prepared by entrapping a liquid electrolyte (1 M LiPF6 in ethylene carbonate/dimethyl carbonate) in the membranes. The composite membranes exhibited a high electrolyte uptake of 450–510%, coupled with an improved room temperature ionic conductivity of up to 4.72 mS cm⁻¹ and a high electrochemical stability of 4.6 V versus Li/Li⁺. Electrochemical investigations of a composite membrane of PAN-PVAc-PAN, with a LiFePO₄ cathode synthesized in-house, showed a high initial discharge capacity of 145 mAh g⁻¹, which corresponds to 85% utilization of the active material, and displayed stable cycle performance.