Reversible H + ‐Lock/Unlock via Enol/Ketone Redox: Parasitic Reactions‐Free Zn Anode and High‐Performance Aqueous Zn‐Ion Batteries

Abstract Aqueous zinc‐ion batteries (AZIBs) have great potential for large‐scale energy storage applications. However, the parasitic reactions, such as continuous hydrogen evolution reaction (HER), seriously hamper the reversibility and cycling stability of the zinc metal anode (ZMA), limiting its practical application. In this paper, a pre‐growth interfacial layer strategy is adopted to grow the enol/ketone conversion interfacial layer on the surface of ZMA (denoted as Zn@AA). H + can be reversible “lock/unlock” during reversible enol/ketone conversion reaction. It not only broadens the capacity of AZIBs (Zn 2+ /H + co‐insertion), but also inhibits the HER reaction (the amounts of H 2 evolution decreased obviously in both Zn@AA||Zn@AA and Zn@AA||VO 2 ·H 2 O@Ppy (Ppy denote as polypyrrole) cells by on‐line differential electrochemical mass spectrometry analysis), thereby improving its stability performance. The cycle life of the assembled Zn@AA||Zn@AA cell exceeded 3200 h at 1 mA cm −2 and 1 mA h cm −2 . Furtherly, the Zn@AA||VO 2 ·H 2 O@Ppy full cell also exhibited excellent cycling stability and capacity retention. This work provides new ideas for modifying the ZMA interfacial layer to inhibit the HER, which guides the development of AZIBs.