Core–Shell Structured Polyimide@γ-Al<sub>2</sub>O<sub>3</sub> Nanofiber Separators for Lithium-Ion Batteries
Yuluo Chen, Jinpeng Luo, Hang Xu, Xinran Hou, Man Gong, Changshu Yang, HuiCong Liu, Xiuqin Wei, Lang Zhou, Chuanqiang Yin, Xiaomin Li
Abstract
Owing to its excellent thermal stability, polyimide (PI) is regarded as one of the most promising alternatives among separators for high-safety lithium-ion batteries (LIBs). Unfortunately, the wettability of the PI separator to electrolytes is still undesirable. The complexation–hydrolyzation method was used to develop a composite membrane with a core–shell structure that anchors γ-Al 2 O 3 nanoparticles on PI nanofiber (PI@γ-Al 2 O 3 ) as an LIB separator. The effects of surface treatment on the physicochemical and electrochemical properties of PI composite membranes are studied in detail, using the pristine PI nanofiber membrane as a reference. The results show that the PI@γ-Al 2 O 3 nanofiber membrane exhibits better physicochemical properties and electrochemical performances. Specifically, the wettability property of the PI@γ-Al 2 O 3 nanofiber membrane is improved with an almost zero contact angle, which significantly meets the requirements of high-performance LIBs. Furthermore, the electrochemical performance of the PI@γ-Al 2 O 3 nanofiber membrane also shows excellent comprehensive properties with the ionic conductivity improving from 0.81 to 1.74 mS cm –1 . Besides, the PI@γ-Al 2 O 3 nanofiber membrane maintains a long charge–discharge process with a capacity retention rate of 98% at 0.5 C after 100 cycles. Consequently, the aforementioned excellent performances illustrate that core–shell PI@γ-Al 2 O 3 nanofiber membranes have a promising future for the safety and stability of LIBs.