Dual polymer (PVDF-HFP and PES) matrix / Li6.4La3Zr1.4Ta0.6O12 composite solid electrolyte with good stability for solid state lithium ion batteries operating at different temperatures

Solid state lithium-ion batteries (SSLIBs) with high safety and high energy density are promising novel energy storage devices. However, the performance of SSLIBs would descend under a wide work temperature range. A flexible ceramic-polymer composite solid electrolyte membrane was created by solution casting to obtain good stability of SSLIBs at different temperatures. The PVDF-HFP-PES-LiClO4-Li6.4La3Zr1.4Ta0.6O12 (LLZTO) composite solid electrolyte shows excellent electrochemical performances in the temperature range of 20 to 60 oC. The ionic conductivity of PVDF-HFP-PES-LiClO4-LLZTO (PPLL) is 4.26 × 10-4, 4.97 × 10-4, 5.26 × 10-4, 5.59 × 10-4 and 5.97 × 10-4 S cm-1 at 20, 30, 40, 50 and 60 oC, respectively. The PPLL was employed in LiFePO4 (LFP)/PPLL/Li batteries, and their properties were tested at 0.2 C. The test results show that the LFP/PPLL/Li battery has a good charge-discharge, rate, and cyclic performance at 20 - 60 oC. After 150 cycles with 0.2C at 30 oC and 60 oC, the capacity retention rates of 75.6% and 86.4%, respectively. This work provides an effective strategy for designing and preparing SSLIBs.