Enhanced electrolyte retention capability of separator for lithium-ion battery constructed by decorating ZIF-67 on bacterial cellulose nanofiber

Abstract

The separator is a key component of the lithium-ion battery (LIB), which not only prevents the anode and the cathode from contacting, but is also related to the performance of the LIB. However, the widely used polyolefin separator has the disadvantages of inferior electrolyte retention capability and poor electrolyte wettability. Therefore, the development of high-performance separators for LIB has attracted widespread attention. In order to enhance the electrolyte retention capacity of the separator, the bacterial cellulose (BC)/zeolitic imidazolate framework-67 (ZIF-67) composite separator was prepared by introducing ZIF-67 on the BC nanofibers. It was found that the introduction of ZIF-67 in BC membrane significantly improved the pore structure and enhanced the electrolyte retention capability, thus contributing to the transfer of lithium-ion, increasing the ionic conductivity (0.837 mS cm−1). In terms of ionic conductivity, BC/ZIF-67 separator has achieved a great improvement compared to polypropylene (PP) separator (0.096 mS cm−1). Besides, the prepared BC/ZIF-67 composite separators hardly shrink at high temperatures. The discharge capacity retention of the LIB using BC/ZIF-67 separator was 91.41% after 100 cycles (0.2 C). Meanwhile, LIB with BC/ZIF-67 separator showed a large discharge capacity (156 mAh g−1) and improved rate performance. Therefore, the BC/ZIF-67 composite membrane has good development potential in the direction of LIB separator.