Electrospun polyacrylonitrile/silica separator with high mechanical strength and electrolyte affinity for aqueous zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs) have gained significant attention due to their intrinsic safety and high capacity. The separator plays a crucial role in high-performance AZIBs. However, the conventional glass fiber (GF) separator with poor mechanical strength suffers from the penetration of zinc dendrites. In this study, we fabricate a polyacrylonitrile/silica composite separator by electrospinning and rolling process. Particularly, we have analyzed the effect of silica loading on physicochemical properties of separators. An optimal content of 30 wt% is achieved, and the separator is denoted as PSO-30. The PSO-30 separator possesses a high mechanical strength of 7.10 MPa, which is 37 times that of GF (0.168 MPa), enabling effective resistance against zinc dendrites. Furthermore, the PSO-30 separator demonstrates competitive ionic conductivity (16.07 mS cm−1), facilitating zinc deposition kinetics. As a result, the symmetric cell with PSO-30 separator exhibits exceptional cycle life exceeding 1150 h at 0.5 mA cm−2. Moreover, the PSO-30 separator improves the energy density and capacity retention of Zn//V2O5 (292 mAh g−1 with a capacity retention of 83.2 %) and Zn//MnO2 (197 mAh g−1 with a capacity retention of 88.9 %) full cells, demonstrating its potential application in AZIBs. This study contributes to developing advanced separators for ultra-stable and high-performance AZIBs.