Porous cellulose diacetate-SiO2 composite coating on polyethylene separator for high-performance lithium-ion battery

•Cellulose diacetate was firstly used to coat on the pristine separator.•The pore structure of coating layer was regulated by the concentration of TEOS.•The modified separators show high tenacity in elevated temperature.•CDA-SiO2 composite coating suppress the growth of Li dendrites. The developments of high-performance lithium ion battery are eager to the separators with high ionic conductivity and thermal stability. In this work, a new way to adjust the comprehensive properties of inorganic-organic composite separator was investigated. The cellulose diacetate (CDA)-SiO2 composite coating is beneficial for improving the electrolyte wettability and the thermal stability of separators. Interestingly, the pore structure of composite coating can be regulated by the weight ratio of SiO2 precursor tetraethoxysilane (TEOS) in the coating solution. The electronic performance of lithium ion batteries assembled with modified separators are improved compared with the pristine PE separator. When weight ratio of TEOS in the coating solution was 9.4%, the composite separator shows the best comprehensive performance. Compared with the pristine PE separator, its meltdown temperature and the break-elongation at elevated temperature increased. More importantly, the discharge capacity and the capacity retention improved significantly.