In Situ Formation of an In-Zn Interface Layer Enables Aqueous Zinc-Ions Batteries with High Capacity Retention

For aqueous zinc ion batteries (AZIBs), inhibiting side reactions is the key to enhance the stability. Particularly, the issues of uneven deposition and hydrogen evolution reaction have attracted intensive attention. We propose to construct an In-Zn interface layer between the separator and anode to induce uniform deposition of metallic zinc. Being different from the traditional direct deposition method, we firstly sputter indium zinc oxide (IZO, In₂O₃:ZnO = 9:1 wt.%) that demonstrates superior zincophilicity on the separator surface as an activator. Then, the activator is reduced to indium during cycling and merges with the anode, in situ forming an In-Zn interface layer. The In-Zn interface layer accelerates the transport of Zn²⁺, facilitates the nucleation/growth of zinc. Meanwhile, the potential of hydrogen release is reduced from -0.051 to -0.077 V. For symmetrical cells (Zn(OTf)₂ electrolyte), a lifespan of over 5000 h at a current density of 1 mA cm^-2 is achieved. For V₆O₁₃-Zn full cells, a capacity of 311.77 mAh g^-1 at 2 A g^-1 is obtained, and the capacity retention reaches 80.72% after 6000 cycles (413.17 mAh g^-1 at 0.1 A g^-1, 82.24% after 633 cycles). Notably, this strategy is universal and also works for AZIBs using ZnSO₄ electrolyte and other cathodes.