Rational design of biomimetic ant-nest solid polymer electrolyte for high-voltage Li-metal battery with robust mechanical and electrochemical performance

Abstract

Solid polymer electrolytes (SPEs), which simultaneously possess high ionic conductivity, robust mechanical properties and reasonable lithium metal compatibility, are highly desired to accelerate the commercialization of solid lithium metal batteries (SLMBs). Herein, a novel biomimetic ant-nest SPE (BASE) is prepared via an in-situ sequential nonhydrolytic reaction of tetraethoxysilane in the poly(vinylidene fluoride-co-hexafluoropropene)-hexafluoropropylene (P(VDF-HFP)) matrix to improve the cyclability of high-voltage SLMBs. BASE, which exhibits a biomimetic ant-nest architecture, not only has high ionic conductivity (0.43 mS cm−1 at 20 °C), but also delivers an outstanding deformation stability without cracking at a 271.17% compressive strain. As a consequence, the Li/LiFePO4 and Li/LiMn0.75Fe0.25PO4 (LMFP) SLMBs show a remarkable cycling stability from room temperature (RT) to 80 °C. As-prepared LMFP based SLMBs exhibit excellent cyclability with 90.9% capacity retention (140.9 mAh g − 1 to 154.9 mAh g − 1) after 200 cycles at 4.2 V under RT. In addition, the Li/LiFePO4 pouch cells exhibit excellent cyclability (nearly 100% capacity retention after 50 cycles) and profound flexibility at RT for potential practical applications. Undoubtedly, this novel BASE opens a new route for designing biomimetic SPEs to develop next-generation SLMBs with high energy density.