Interfacial Molecule Engineering for Reversible Zn Electrochemistry

The unstable Zn interface caused by undesired dendrites and parasitic side reactions greatly impedes the deployment of aqueous Zn metal batteries. Herein, an efficient adsorptive additive strategy is proposed to reshape the electric double layer and regulate Zn interfacial chemistry. 2-Hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone (Irgacure 2959) was selected owing to its strong adsorption ability, intermolecular hydrogen bonding, and exposed strong electronegative carbonyl group. The constructed self-adaptive adlayer contributes to a localized H2O, SO42–-poor environment and horizontal alignment of Zn deposits along the (002) plane, thus endowing thermodynamically stable and highly reversible Zn electrochemistry. As a result, reversible plating/stripping of 3800 h and high Coulombic efficiency of 99.8% are achieved. Intriguingly for practical application, the economical additive (0.016 USD L–1) enables stable discharge output for 500 cycles in Zn/VS2 cells at a low negative-to-positive capacity ratio of 2.5 (cathode mass loading: 10.8 mg cm–2), holding great promise for use in a scalable, low-cost, rechargeable battery.