Improved electrochemical performance of aqueous zinc-ion batteries with modified glass fiber separator by Ketjen Black

The development of aqueous zinc-ion batteries (AZIBs) with high capacity and high cycling stability has drawn increasing attention in recent years. Herein, a novel separator modification technology by spraying Ketjen black (KB) conductive carbon layer on the side of cathode is developed for improving the capacity and cycle stability of AZIBs. Benefiting from the KB separator, the Zn/MnO2 battery shows a high reversible specific capacity of 194.6 mAh g−1 at a current density of 2 A g−1 in a long-term cycle of 1500 cycles. In addition, the battery maintains 87% capacity retention after 6000 cycles at the current density 5 A g−1. The results indicate that the KB separator reduces the charge transfer impedance and improves the ion diffusion coefficient, showing excellent electrochemical kinetics. Meanwhile, the unique adsorption properties of KB separator reduce the attachment of by-products on the cathode surface. And the KB separator electrooxidizes Mn2+ ions on the surface to generate electrochemically active layered birnessite. Birnessite not only balances the capacity fading of the battery, but also improves the capacity of the battery, so that the battery has stable electrochemical performance. The method adapted in this work provides valuable insights for designing high performance aqueous zinc-ion secondary batteries.