PEO-based composite solid electrolyte for lithium battery with enhanced interface structure

Abstract

Solid electrolyte (SE) is advantageous in inhibiting the growth of dendrites and avoiding battery short circuit as well as explosion. However, poor ionic conductivity and unstable interfacial contact have been the inherent issues of SEs. In general, the use of effective fillers and additives is regarded as the feasible solution to compensate for these issues. In this study, a polyethylene oxide (PEO)-based composite SE (P-P-L) with both LiAlO2 (LAO) and polyacrylonitrile (PAN) additives was prepared to integrate the merits of inorganic and organic additives. Nanostructured LAO fillers formed a large number of ion transport regions in the matrix, which led to the increase in the ionic conductivity of the electrolyte to 3.60 × 10–4 S cm−1 at 60 °C. Moreover, the PAN additive could interact with lithium sheets to form Li3N, which significantly reduced the interfacial impedance and improved the battery stability. As expected, the symmetric battery stably circulated for nearly 1000 h at 60 °C under current density of 0.1 mA cm−2. The P-P-L, LiFePO4 (LFP) cathode, and lithium sheet anode were assembled into the lithium metal battery, whose capacity retention rate could reach 92.0 % after 200 cycles at 60 °C under a current density of 0.5 C. The application of this electrolyte provides an efficient strategy for solving the interface problem of SE.