Trapping Anions to Govern the Li+ Local Coordination Environment for a Highly Li+ Conductive Solid Polymer Electrolyte

Abstract

Solid polymer electrolytes (SPEs) confront the major challenge of low ionic conductivity. The Li⁺ local coordination environment in SPEs affects the ionic conductivity. Herein, a highly ionic conductive SPE is designed and experimentally realized via governing the Li⁺ local coordination environment through 4-acetylphenylboronic acid (APBA). The –OH functional groups in APBA react with F atoms in the PVDF-HFP polymer chain segment and O atoms in TFSI^– to form the OH···F hydrogen bond and the OH···O hydrogen bond. This weakens the Li⁺ local coordination with PVDF-HFP and TFSI^–, facilitating more free-Li⁺ release and strengthening the molecular dynamics of Li⁺. This variation results in the greatly increased Li⁺ ionic conductivity from 0.63 × 10^–4 to 2.39 × 10^–4 S/cm of SPE with APBA at 25 °C. This electrolyte makes the symmetric cells full cells with promising electrochemical performance. The strategy provided here is helpful for the development of highly ionic conductive SPEs.