A promising composite solid electrolyte incorporating LLZO into PEO/PVDF matrix for all-solid-state lithium-ion batteries

摘要

Solid electrolytes should be sought to exhibit high conductivity, good thermostability, and excellent mechanical properties for realizing excellent performance of lithium-ion batteries. In this study, we optimize the composition of poly(ethylene oxide)/poly(vinylidene fluoride) (PEO/PVDF) matrix and introduce Li6.2Ga0.1La3Zr1.5Bi0.5O12 (LLZO) ceramic powders into the matrix to form novel composite solid electrolytes. The PEO/PVDF blend matrix shows a low melting point and crystallinity and a high thermostability when the weight ratio of PEO and PVDF is 7:3. The electrolyte consisting of this PEO/PVDF blend matrix and 10 wt% LLZO shows the maximum conductivity (4.2 x 10(-5) S cm(-1) at 30 degrees C). In addition, all-solid-state LiFePO4||Li battery assembled with this solid electrolyte shows good cycling stability, which retained 96.5% of the maximum capacity after 100 cycles, and columbic efficiency (close to 100%) at 60 degrees C. The Li||Li symmetric battery assembled with the solid electrolyte can be steadily cycled for more than 300 h at a current density of 0.2 mA cm(-2) at 60 degrees C. Hence, the new as-synthesized solid electrolyte should be a promising electrolyte for high performance of all-solid-state batteries.