A blended gel polymer electrolyte for dendrite-free lithium metal batteries

Solid-state lithium metal batteries (SSLMBs) are promising candidates for the application in electric vehicles (EVs) because of their higher energy density and safer properties compared to the traditional liquid organic electrolyte-based lithium-ion batteries (LIBs). However, SSLMBs with solid polymer electrolyte (SPE) suffer from the serious lithium dendrite problem, which results in the poor cycling performance and the short circuit of batteries. In this work, a thin and flexible blended gel polymer electrolyte (GPE) was prepared for dendrite free SSLMBs. The as-prepared GPE has a strong strain at 529.94 ± 10%, a high ion transference number (t_Li+) of 0.66, and a wide electrochemical window of 5.23 V (vs. Li⁺/Li). Mechanism study shows that the addition of fluoroethylene carbonate (FEC) into the GPE promotes the formation of LiF-coating solid electrolyte interphase (SEI). As a result, a stable GPE/Li-metal interface and dendrite-free SSLMB was achieved. Moreover, the solid-state battery with Li-metal anode, as-prepared SPE and LiFePO₄ can deliver a specific capability of 150 mAh g⁻¹ and a capacity retention of 94.8 % after 500 cycles at 0.3C, 20 ℃.