Hybrid Poly(Ethylene Oxide)-Based composite polymer electrolyte for high-performance all-solid-state lithium batteries

Abstract

Composite solid-state electrolytes (CSSEs) using solid-state lithium metal batteries (SSLMBs) are widely used as one among the primary technological paths aimed towards chemically necessary safety with acceptable energy density. Nevertheless, the unchecked growth of lithium dendrites and the sluggish transport of lithium ions impede the development of SSLMBs based on CSSEs. Herein, the simultaneous introduction of multilayer g-C3N4 and exceptionally thermally stable boron nitride (BN) into the PVDF/PEO system is presented. Benefitting from the unique trait and synergistic effect of g-C3N4 and BN in the synthesized CSSEs (g-C3N4/BN/PVDF/PEO-LiTFSI), the prepared CSSEs yield excellent Li+ transfer number (0.75), surprising thermal stability (shrinkage of only 14.13% after heated at 130 °C for 4 h), and high electrochemical stability window over 4.73 V vs. Li/Li+, which are much higher than those reported in the current literature PEO-based CSSEs. Moreover, the Li||CSSEs||LiFePO4 cell applying the CSSEs attained outstanding cycling stability (capacity retention rate of 85% after 350 cycles) and excellent rate performance (58.6 mAh g−1 at 5C). This study offers a simple, promising application, robust, and scalable manufacturing strategy to develop a dual role for stable and safe polymer-based all-solid-state lithium batteries.