Crystalline Al2O3 modified porous poly(aryl ether ketone) (PAEK) composite separators for high performance lithium-ion batteries via an electrospinning technique†
The thermostability and wettability of a separator play key roles in improving the safety and electrochemical properties of lithium-ion batteries (LIBs). Given this fact, a crystalline aluminium oxide (Al2O3) nanoparticle coated poly(aryl ether ketone) (PAEK) composite membrane with excellent comprehensive properties was fabricated by an electrospinning technique, and further used as a porous separator for high-performance lithium-ion batteries (LIBs). The structure, thermal stability, morphology, liquid electrolyte uptake, porosity, contact angle, ionic conductivity and electrochemical performance of the PAEK–Al2O3 blend separator were investigated. Notably, the PAEK–Al2O3 separator showed much stronger anti-shrinkage properties (no dimensional changes) than a commercial polypropylene (PP) separator (severe thermal shrinkage) at 150 °C over 1 h. In addition, compared with those of PAEK and commercial PP separators, the degradation temperatures of the PAEK–Al2O3 separator were higher, with values over 500 °C. The PAEK–Al2O3 separator also had superior electrolyte wettability, and its electrolyte uptake reached 561%. The porosity and ionic conductivity of the composite separator were 89.4% and 3.15 mS cm−1, respectively. As a result of the abovementioned outstanding properties of the blend separator, the cell assembled from the PAEK–Al2O3 separator exhibited a high discharge capacity of 158.2 mA h g−1 (LiFePO4/Li+) during 100 cycles and a superior C rate performance. Hence, the obtained PAEK–Al2O3 separator enhanced the safety and electrochemical properties of the corresponding LIB.