Dendrite-free and anti-corrosion Zn metal anode enabled by an artificial layer for high-performance Zn ion capacitor

Aqueous zinc energy storage devices, holding various merits such as high specific capacity and low costs, have attracted extensive attention in recent years. Nevertheless, Zn metal anodes still suffer from a short lifespan and low Coulombic efficiency due to corrosion and side reactions in aqueous electrolytes. In this paper, we construct an artificial Sn inorganic layer on Zn metal anode through a facile strategy of atom exchange. The Sn layer suppresses Zn dendrite growth by facilitating homogeneous Zn plating and stripping during charge and discharge processes. Meanwhile, the Sn protective layer also serves as a physical barrier to decrease Zn corrosion and hydrogen generation. As a result, The Sn-coated anode (Sn|Zn) exhibits a low polarization voltage (∼34 mV at 0.5 mAh/cm2) after 800 testing hours and displays a smooth and an even surface without corrosion. Moreover, the zinc ion capacitor (Sn|Zn||activated carbon) is assembled with an enhanced capacity of 42 mAh/g and a capacity retention of 95% after 10,000 cycles at 5 A/g. This work demonstrates a feasible approach for the commercialization of aqueous Zn-based energy storage devices.