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) nanoparticles coating poly(aryl ether ketone) (PAEK) composite membrane with excellent comprehensive properties was fabricated by electrospinning technique, and further used as 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 blending separator were investigated. Notably, the PAEK-Al2O3 separator showed much stronger anti-shrinkage properties (no dimensional changes) than the commercial polypropylene (PP) separator (severe thermal shrinkage) at 150 °C over 1 h. In addition, compared with the 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 wettabilities, and their electrolyte uptake reached 561%. The porosity and ionic conductivity of the composite separators were 89.4% and 3.15 mS cm-1, respectively. As a result of the abovementioned outstanding properties of the blending separator, the cell assembled from this PAEK-Al2O3 separator exhibited a high discharge capacity of 158.2 mAh 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.