Fabrication of poly (vinylidene fluoride) separator with better thermostability and electrochemical performance for lithium ion battery by blending polyester

Abstract The poly (vinylidene fluoride)/polyester (PVDF/PET) separator for lithium ion battery was successfully prepared using thermally induced phase separation (TIPS) technique for the first time. PET was used to enhance thermostability and regulate the micro-structure of separator. The results indicated that although solid-liquid phase separation occurred for PVDF/PET/diluent dope, the introduction of PET is in favor of forming network structure, which can be attributed to the change of compatibility and confined crystallization of PVDF. Compared with the pristine separator, the blend separator exhibited a better thermostability, higher capacity (151.5 mAh g −1 vs 133.7 mAh g −1 for initial discharge capacity) and decomposition voltage (4.7 V vs 4.5 V). The investigations suggested that the prepared PVDF/PET separator is a good candidate for lithium ion battery.