Evaporation and in-situ gelation induced porous hybrid film without template enhancing the performance of lithium ion battery separator.

The current commercialized polyethylene (PE) separator has poor wettability and thermal stability which will seriously restrict the electrochemical performance and affect the safety of lithium ion battery. Herein, a porous hybrid layer coated separator with high thermal stability, good electrochemical performance and improved wettability was prepared by a template-free method via the synergistic effect between tetraethoxysilane (TEOS) and aramid nano fibers (ANFs) during the evaporation of solvent and the in-situ gelation of TEOS. The results show that the porous hybrid coating layers can enhance the thermal stability, wettability and electrolyte uptake of the separators. Moreover, the lithium ion transference number is also increased. As a result, the battery assembled with the composite separator exhibits enhanced electrochemical performance in terms of cycle stability and rate performance. When coupled with LiCoO2cathode, the capacity retention rate is as high as 96.0% after 100 cycles at 0.2C.