An all-solid-state lithium battery using the Li₇La₃Zr₂O₁₂ and Li_6.7La₃Zr_1.7Ta_0.3O₁₂ ceramic enhanced polyethylene oxide electrolytes with superior electrochemical performance

As a core component of all-solid-state lithium batteries (ASSLBs), composite solid electrolytes (CSEs) have good safety, high ionic conductivity and certain flexibility. Here, we report that the CSEs is composed by mixing the Li₇La₃Zr₂O₁₂ (LLZO) and Li_6.7La₃Zr_1.7Ta_0.3O₁₂ (LLZTO) ceramic filler, polyethylene oxide (PEO) and LiTFSI. The ionic conductivity of the optimized CSEs is as high as 1.7 × 10⁻⁴ S cm⁻¹ at 30 °C, the electrochemical stability window is 5.4 V, and the lithium ion transference number is 0.5 at 60 °C. In addition, the uniform distribution of ceramic particles enhances the thermal stability, mechanical strength and the interfacial compatibility of the CSEs, which inhibits the growth of lithium dendrites. The assembled LiFePO₄/PEO-LiTFSI-10 wt% Li_6.7La₃Zr_1.7Ta_0.3O₁₂/Li battery exhibited excellent cycle and rate performance at 60 °C. The initial discharge capacity was 140 mA h g⁻¹ at a current density of 0.2 C, and the discharge capacity was maintained 139.4 mA h g⁻¹ after 200 cycles.