In situ generated tin protective layers from stannous oxalate for dendrite-free zinc anodes

Aqueous zinc-ion batteries (AZIBs) have become popular for energy storage devices due to their cost-effectiveness, high capacity and environmental friendliness. However, the uncontrolled growth of dendrites and corrosion at the zinc anode have seriously hindered AZIBs’ further development. The construction of protective interface layers is a promising strategy to mitigate and suppress the above problems. Herein, we propose the in situ construction of a protective layer of Sn at the zinc anode by coating a suspension of stannous oxalate, which regulates the zinc nucleation sites and induces the deposition of Zn (002) crystal planes, inhibiting the uncontrolled growth of zinc dendrites. The hydrophobic Sn metal protective layer isolated the contact between the active water and the zinc anode and suppressed the corrosion of the zinc anode. As a result, the modified Zn//Zn symmetric cell has a cycle life of 2300 h at 1 mA cm−2, with a significant reduction in the polarisation overpotential. The MnO2//Zn full cell assembled with the modified Zn anode also showed good performance with a specific capacity of 94.74 mA h g−1 after 1000 cycles. This work exemplifies the potential of metal salts in the development of stable metal electrodes.