Synergetic control of hydrogen evolution and ion-transport kinetics enabling Zn anodes with high-areal-capacity

Intrinsic uneven Zn deposition-dissolution and hydrogen evolution reaction (HER) induce poor reversibility and limited cycle life of Zn anodes, which thus restrict the practical application of rechargeable aqueous Zn batteries. In this work, a synergistic strategy of porous indium (In) coating layer combined with a polyacrylamide (PAM) polymer layer for Zn anodes is proposed to provide large HER overpotential while facilitating fast and homogeneous Zn2+ transport at the electrode-electrolyte interface. The corrosion reaction and Zn dendrite growth are simultaneously prevented at high utilization of Zn anodes. The optimal ZnIn-PAM electrodes demonstrate outstanding cycling stability at ultra-high current density and areal capacity (10 mA cm−2, 10 mAh cm−2, Zn utilization: 57%) for over 400 h, and long-term lifespan for over 1700 h at 5 mA cm−2 and 5 mAh cm−2 (Zn utilization: 28.5%) with only ∼50 mV overpotential. Coupled with electrolytic manganese dioxide cathode, the full cell delivers ultra-long lifespan of 10000 cycles with capacity decay rate of 0.006% per cycle at 5 C. This work provides useful perspective for exploring synergetic strategies to address the limited cycling stability of Zn metal-based aqueous batteries for practical use.