Highly reversible and dendrite-free Zn electrodeposition enabled by a thin metallic interfacial layer in aqueous batteries

Zinc (Zn) metal is regarded as a promising anode material for aqueous batteries owing to its high natural abundance, high theoretical capacity and low redox potential. However, aqueous Zn metal anodes suffer from poor reversibility, as shown by their low Coulombic efficiency (CE) and dendrite growth during long-term plating/stripping. In this study, we report that a thin metallic Cu or Ag interfacial layer, made by a facile thermal evaporation method, can enable highly reversible and nondendritic plating/stripping of Zn metal anodes in aqueous batteries. This is attributed to the synergy of fast Zn-ion migration through the tiny gaps in the interfacial layer as well as its high interfacial affinity for Zn metal. High average CE of 99.7% are achieved over 3000 plating/stripping cycles at 10 mA cm−2 and 1 mAh cm−2. The modified Zn anode can stably cycle for more than 2500 cycles (5000 h) of plating/stripping at 1 mA cm−2 and a 500 cycle-life is realized for a full cell paired with a MnO2 cathode. This finding opens up a promising avenue to develop the next-generation Zn metal-based energy storage technologies.