Modification of Lithium Ion Battery Separator with Ceramic Coating Using Phase Inversion

In order to improve the liquid electrolyte uptake, wetting ability to electrolyte solution, thermal stability and electrochemical stability of the polyethylene(PE) separator membranes, the PE separator membranes were coated with polyvinylene fluoride(PVDF) and nano aluminum oxide (nano-Al2O3) to form porous ceramic coating using phase inversion. Results show that when the mass fraction of PVDF to nano-Al2O3 is 0.15 and 0.3, respectively, in coating solution, the liquid electrolyte uptake increases by 211.5%, water contact angle reduces by 41.3°, thermal decomposition temperature and electrochemical stability window increase by 73.4 °C and 0.2 V respectivedy compared to the unmodified membrane. The capacity retention rate of the modified membrane reaches 96.17%, while that of the unmodified one is only 85.78%, which means that wetting ability, stability, security and cycling performance of the modified membrane is enhanced greatly.