Ion Sieve Interface Assisted Zinc Anode with High Zinc Utilization and Ultralong Cycle Life for 61 Wh/kg Mild Aqueous Pouch Battery

The cycling stability of a thin zinc anode under high zinc utilization has a critical impact on the overall energy density and practical lifetime of zinc ion batteries. In this study, an ion sieve protection layer (ZnSnF@Zn) was constructed in situ on the surface of a zinc anode by chemical replacement. The ion sieve facilitated the transport and desolvation of zinc ions at the anode/electrolyte interface, reduced the zinc deposition overpotential, and inhibited side reactions. Under a 50% zinc utilization, the symmetrical battery with this protection layer maintained stable cycling for 250 h at 30 mA cm^-2. Matched with high-load self-supported vanadium-based cathodes (18-20 mg cm^-2), the coin battery with 50% zinc utilization possessed an energy density retention of 94.3% after 1000 cycles at 20 mA cm^-2. Furthermore, the assembled pouch battery delivered a whole energy density of 61.3 Wh kg^-1, surpassing the highest mass energy density among reported mild zinc batteries, and retained 76.7% of the energy density and 85.3% (0.53 Ah) of the capacity after 300 cycles.