A Composite Gel Polymer Electrolyte with High Performance Based on Poly(Vinylidene Fluoride) and Polyborate for Lithium Ion Batteries

TLDR

A composite membrane of electrospun PVDF and LiPVAOB delivers high safety, robust mechanical strength, retains electrolyte solvent at elevated temperatures, and is evaluated with LiFePO₄ cathodes. The gel polymer electrolyte attains 0.26 mS cm⁻¹ ionic conductivity and 0.58 lithium‑ion transference at room temperature, outperforming the commercial Celgard separator, and indicating suitability for high‑safety, large‑capacity lithium‑ion batteries.

Abstract

A composite membrane based on electrospun poly(vinylidene fluoride) (PVDF) and lithium polyvinyl alcohol oxalate borate (LiPVAOB) exhibiting high safety (self‐extinguishing) and good mechanical property is prepared. The ionic conductivity of the as‐prepared gel polymer electrolyte from this composite membrane saturated with 1 mol L −1 LiPF 6 electrolyte at ambient temperature can be up to 0.26 mS cm −1 , higher than that of the corresponding well‐used commercial separator (Celgard 2730), 0.21 mS cm −1 . Moreover, the lithium ion transference in the gel polymer electrolyte at room temperature is 0.58, twice as that in the commercial separator (0.27). Furthermore, the absorbed electrolyte solvent is difficult to evaporate at elevated temperature. Its electrochemical performance is evaluated by using LiFePO 4 cathode. The obtained results suggest that this gel‐type composite membrane shows great possibilities for use in large‐capacity lithium ion batteries that require high safety.