Study on structure and electrical properties of PVDF/Li3/8Sr7/16Zr1/4Ta3/4O3 composite solid polymer electrolytes for quasi-solid-state Li battery

Abstract

Flexible composite solid polymer electrolytes (CSPEs) with good interfacial contact with electrodes and high stability against Li are promising candidate materials for quasi-solid-state Li battery. Herein, perovskite Li3/8Sr7/16Zr1/4Ta3/4O3 (LSZT) with high conductivity (> 10−4 S·cm−1) and Li+ transference number (∼1) as the active filler was added to polyvinylidene fluoride (PVDF)+bis(trifluoromethanesulfonyl)imide (LiTFSI) polymer matrix to improve its performances. The X-ray diffraction pattern and Fourier transform infrared measurements showed that the structure of CSPEs comprised α, β, and γ mixed phases. The CSPE containing 10% LSZT powder (CSPE-10%) exhibited a high conductivity of 6.26 × 10−5 S·cm−1 at 20°C, thermal stability up to 353°C, electrochemical stability up to 4.61 V, and Li+ transference number of 0.54. The galvanostatic charge/discharge measurements using Li/CSPE-10%/Li cell showed that CSPE exhibited steady cycling at 0.05 mA·cm−2 for more than 300 h. LiFePO4/Li battery with CSPE-10% displays a high specific discharge capacity of 133.6 mAh·g−1 with 0.2 C rate at 25°C, along with good stable performance over 300 cycles.