Effect of Al2O3/SiO2 composite ceramic layers on performance of polypropylene separator for lithium-ion batteries

In order to improve the safety of lithium-ion batteries, Al2O3/SiO2 composite ceramic layers were introduced on both sides of polypropylene (PP) separator surface. SiO2 is used to form porous network, and Al2O3 is evenly distributed in it. The introduction of Al2O3/SiO2 composite ceramic layers can not only restrict the motion of separator but also resist the protrusion of the separator, so the composite separator has lower thermal shrinkage and higher mechanical properties. As the composite layers can retain additional liquid electrolyte, the composite separator has higher electrolyte uptake and ionic conductivity. Cell performance, such as C-rate capability and cycle performance, were also investigated and compared to those obtained with pristine separator and only SiO2 coated separator.