A facile preparation of PEO–LiClO4–fumed SiO2 composite solid-state electrolyte with improved electrochemical performance for lithium-metal batteries

In order to improve the electrochemical performance and efficiently prepare a solid polymer electrolyte (SPE) for the lithium-metal battery (LMB), a fumed SiO2 (FS) with surface Si–OH group was used to fabricate FS-modified poly(ethylene oxide) (PEO)–LiClO4-based SPE by a facile preparation process. The influences of the FS content on the morphological properties, thermal properties, lithium salt dissociation, mechanical properties, and electrochemical properties of SPE were systematically analyzed. Results indicate that FS with the hydrophilic property was widely distributed throughout the amorphous phase of SPE, thus the crystallinity of SPE was reduced to 25.83% when the FS mass loading was 6.85 wt%. In addition, a greater dissociation degree of lithium salt was achieved after the addition of FS, and a higher ion conductivity of 3.03 × 10−4 S cm−1 and Li-ion migration number of 0.396 were recorded at 60 °C. The all-solid-state Li/SPE/Li coin cell showed excellent stable cyclability (380 h) and the LiFePO4 (LFP)/SPE/Li coin cell demonstrated good discharge specific capacity and coulomb efficiency of 96 mA h g−1 and 100.2%, respectively, after 100 cycles of galvanostatic charge–discharge operation under 0.5C at 60 °C. Thus, based on collective results, it is expected that SPE presented in this work is a promising electrolyte for next-generation high-energy all-solid-state LMB with enhanced safety.