Electrospun Polybenzimidazole Separator With Superior Performance for Zinc Ion Battery

Zinc-ion batteries (ZIBs) have gained popularity due to their inherent safety and high capacity. Nonetheless, Zn²⁺ deposition grows uncontrollably and swiftly passes through the separator. We address this challenge by introducing an innovative electrospun polybenzimidazole (PBI) separator that possesses exceptional thermal stability and electrolyte wettability. The abundance of C-N, C-C, and N-H functional groups in the PBI separator, which exhibit strong interactions with Zn²⁺, modifies the solvation structure of Zn²⁺ and enhances the wettability of the anode-electrolyte. The rigid structure and functional groups of the PBI chain enable separators to maintain stability at temperatures up to 400°C. This leads to an extraordinary cycle life of over 400 h at a high current density of 5 mA cm⁻² for the symmetric cell with a PBI separator. In addition, the PBI separator allows for a MnO₂/Zn battery to have excellent rate capability and ultralong cyclability. These findings help build ZIBs with great stability and safety at high temperatures, making them suitable for energy storage and powering high-demand devices.