Ultrathin Zincophilic Interphase Regulated Electric Double Layer Enabling Highly Stable Aqueous Zinc-Ion Batteries

Abstract The practical application of aqueous zinc-ion batteries for large-grid scale systems is still hindered by uncontrolled zinc dendrite and side reactions. Regulating the electrical double layer via the electrode/electrolyte interface layer is an effective strategy to improve the stability of Zn anodes. Herein, we report an ultrathin zincophilic ZnS layer as a model regulator. At a given cycling current, the cell with Zn@ZnS electrode displays a lower potential drop over the Helmholtz layer (stern layer) and a suppressed diffuse layer, indicating the regulated charge distribution and decreased electric double layer repulsion force. Boosted zinc adsorption sites are also expected as proved by the enhanced electric double-layer capacitance. Consequently, the symmetric cell with the ZnS protection layer can stably cycle for around 3,000 h at 1 mA cm −2 with a lower overpotential of 25 mV. When coupled with an I 2 /AC cathode, the cell demonstrates a high rate performance of 160 mAh g −1 at 0.1 A g −1 and long cycling stability of over 10,000 cycles at 10 A g −1 . The Zn||MnO 2 also sustains both high capacity and long cycling stability of 130 mAh g −1 after 1,200 cycles at 0.5 A g −1 .