A High Ceramic Loading LATP-PVDF-Al2O3 Composite Film for Lithium-ion Batteries with Favorable Porous Microstructure and Enhanced Thermal Stability

Abstract

A separator plays a crucial role in a Li-ion battery to carry liquid electrolytes while preventing short-circuiting between electrodes. Nevertheless, conventional commercial separators often exhibit poor wettability and are prone to shrink at elevated temperatures due to their limited thermal stability. Herein, we report a heat-resistant LATP-PVDF-Al2O3 composite film with outstanding wetting performance. The thin film was prepared using ball-mill mixing and tape-casting processes. Two solvents NMP and glycerol were applied to prepare the slurry and a favorable microstructure in the film was created after drying. The ionic conductivity of the film was tested at 1.39 mS cm−1 when paired with liquid electrolyte, almost double that of the commercial counterpart. The high ceramic loading of 70% improved both the thermal shrinkage resistance and dendrite inhibition of the membrane. When assembled in an NMC half-cell, the cycling capacity retentions of 92.8% and 92.1% are achieved after 50 cycles at 0.5 C and 1 C, demonstrating its capability to be used in Li-ion batteries.