Nano-silica-decorated Poly(m-Phenylene Isophthalamide) Separator with Enhanced Mechanical and Electrolyte Wetting Properties for Lithium-Ion Batteries

Heat-resistant poly(m-phenylene isophthalamide) (PMIA) has attracted considerable attention as a novel separator for application in lithium-ion batteries (LIBs); however, its mechanical strength and electrolyte wettability are not ideal. Herein, a nano-silica-decorated poly(m-phenylene isophthalamide) (PMIA@SiO2) separator was fabricated with SiO2 nanoparticles uniformly attached to the pores and pore walls of the PMIA separator. The as-prepared PMIA@SiO2 separator has good mechanical strength (a 16% improvement compared with pristine PMIA) and wettability toward the electrolyte (the contact angle decreases from 34.0° to 23.1°). The PMIA@SiO2 separator also had a high ionic conductivity (0.75 mS/cm) and low interfacial electric resistance (75 Ω). The assembled LiCoO2/PMIA@SiO2-liquid electrolyte/Li cell displays good cycle performance with a capacity retention of 88.1% after 50 cycles. Furthermore, the cycling performance and rate capacity rarely changed after high-temperature treatment. Therefore, the nano-silica-decorated PMIA separator is a potential candidate for application in LIBs with high safety.