Ionic potency regulation of coagulation bath induced by saline solution to control over the pore structure of PBI membrane for high-performance lithium metal batteries

In this study, we have explored the use of water as a non -solvent for tuning the microstructure of polybenzimidazole (PBI) membranes, which are potential separators for lithium metal batteries (LMBs). The traditional method for membrane synthesis called nonsolvent-induced phase separation (NIPS), usually relies on hazardous and costly organic non -solvents. By dissolving sodium chloride (NaCl) in water, we could adjust the water ionic potency and the exchange speed of the non -solvent with the DMAC solution to change the micropore structure of the PBI membrane. With increasing NaCl concentration, the micropores in the PBI membrane transitioned from finger -like to sponge -like morphology. Compared to commercial separators like the Celgard separator, the PBI membrane with sponge -like micropores exhibited better regulation of lithium deposition and improved Li + transportation capability due to its good wettability with the electrolyte. Consequently, the PBI membrane -based Li/Li symmetric cell and Li/LiFePO 4 full cell demonstrated superior performance compared to the Celgard-based ones. This research proposes an eco-friendly and scalable synthetic approach for fabricating commercial separators for LMBs, addressing the issue of lithium dendrite growth and improving overall battery safety and performance. (c) 2024 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.