Recent Advances in Polyacrylonitrile-Based Separators for Aqueous Zinc-Ion Batteries

The electrical energy enhances the proliferation of electronic devices in the modern era. Typically, most electronic devices run on a lithium-ion battery (LIB). However, safety issues prompt researchers to consider alternatives, and the aqueous zinc-ion battery (AZIB) emerged as an alternative with higher merits. One of the fundamental segments of the AZIB is the separator that provides ion transportation on both sides of the battery while deterring direct contact between the cathode and anode. For AZIBs, glass fiber (GF) is the most conventional separator considering their availability and cost-effectiveness, suffering from various hurdles, for instance, dendrite formation, which is the primary concern, causing an explosion during battery operation, and the low mechanical strength. Conversely, the polyacrylonitrile (PAN) prevents dendrite formation through the electrostatic interaction, deposition along the (002) plane, 3D diffusion, and selective zinc ion permeation, and offers high cyclability. We segment this paper into four parts: first, it discusses the basic features of the ideal separator; second, the preparation methods of the separator; third, a critical overview of the PAN-based separator for AZIB, especially the dendrite mitigation strategies; and finally, it provides the future directions and strategies for advance PAN-based separator design.