In situ formation of solid electrolyte interphase facilitates anode-free aqueous zinc battery

Aqueous Zn batteries (AZBs) suffer from poor Zn anode reversibility. To address this issue, excess Zn foil is often utilized to prolong the cycle life, but it reduces the actual battery energy density. In this work, we use methylurea molecules to in situ form a solid electrolyte interphase (SEI) layer on the Zn anode, achieving reversible Zn plating/stripping with a maximal Coulombic efficiency (CE) of 99.99% and extending the anode's lifespan to 4500 cycles. Leveraging this highly reversible chemistry, we fabricate and test various anode-free Zn batteries. An anode-free Zn–AC cell exhibits stable cycling for exceeding 5000 cycles, an anode-free Zn–I 2 battery with high specific capacities achieves a stable…