Polyethylene separator activated by γ-ray irradiation for improving lithium-based battery performance

The separators have an impact on the performance of lithium-based battery, whereas traditional polyolefin separators are hard to retain enough liquid electrolyte for its nonpolar surface and lead to battery performance degradation. In this experimental work, we have tried to activate polyethylene (PE) separator by γ-ray irradiation with different doses. According to these results of FTIR-ATR, the contact angle and mechanical test, it is concluded that γ-ray irradiation would get the PE long chains broken and oxidized furtherly. Therefore, these irradiated separators show a higher surface energy and inferior mechanical strength than pristine PE separator. For comprehensive consideration, the PE-20 (irradiated by the dose of 20 kGy) separator is selected to evaluate the electrochemical performance. The LiCoO2 cells with PE-20 separators have a better cyclic stability than that of PE separator for lower interfacial resistance and stronger affinity to liquid electrolyte. Especially in the unsymmetrical rate performance test, the cells based on PE-20 separator have higher discharge capacity. It demonstrates that this method of γ-ray irradiation could be used to modify PE separator for enhancing battery performance.