Ameliorating the interfacial issues of all-solid-state lithium metal batteries by constructing polymer/inorganic composite electrolyte

Lithium metal is one of the most promising anodes for next-generation batteries due to its high capacity and low reduction potential. However, the notorious Li dendrites can cause the short life span and safety issues, hindering the extensive application of lithium batteries. Herein, Li₇La₃Zr₂O₁₂ (LLZO) ceramics are integrated into polyethylene oxide (PEO) to construct a facile polymer/inorganic composite solid-state electrolyte (CSSE) to inhibit the growth of Li dendrites and widen the electrochemical stability window. Given the feasibility of our strategy, the designed PEO-LLZO-LiTFSI composite solid-state electrolyte (PLL-CSSE) exhibits an outstanding cycling property of 134.2 mAh g⁻¹ after 500 cycles and the Coulombic efficiency of 99.1% after 1000 cycles at 1 C in LiFePO₄-Li cell. When cooperated with LiNi_0.6Co_0.2Mn_0.2O₂ (NCM622) cathode, the PLL-CSSE renders a capacity retention of 82.4% after 200 cycles at 0.2 C. More importantly, the uniform dispersion of LLZO in PEO matrix is tentative tested via Raman and FT-IR spectra and should be responsible for the improved electrochemical performance. The same conclusion can be drawn from the interface investigation after cycling. This work presents an intriguing solid-state electrolyte with high electrochemical performance, which will boost the development of all-solid-state lithium batteries with high energy density.