An all-solid-state lithium battery using the Li7La3Zr2O12 and Li6.7La3Zr1.7Ta0.3O12 ceramic enhanced polyethylene oxide electrolytes with superior electrochemical performance

Abstract

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 Li6.7La3Zr1.7Ta0.3O12 (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% Li6.7La3Zr1.7Ta0.3O12/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.