Sulfurized Composite Interphase Enables a Highly Reversible Zn Anode

The stability and reversibility of Zn anode can be greatly improved by in‐situ construction of solid electrolyte interphase (SEI) on Zn surface via a low‐cost design strategy of ZnSO4 electrolyte. However, the role of hydrogen bond acceptor ‐SO3 accompanying ZnS formation during SEI reconstruction is overlooked. In this work, we have explored and revealed the new role of ‐SO3 and ZnS in the in‐situ formed sulfide composite SEI (SCSEI) on Zn anode electrochemistry in ZnSO4 aqueous electrolytes. Structure characterization and DFT demonstrate that the introduction of ‐SO3 can not only reduce the dehydration energy of [Zn(H2O)6]2+, but also enhance the stability of the ZnS/Zn interface and homogenize the ZnS/Zn interface electric field, thereby significantly improving the dynamic kinetics and uniform deposition of Zn2+. Owing to the synergistic effect of ZnS and ‐SO3, a high cycling stability of 1500 h with a cumulative‐plated capacity of 7.5 Ah cm‐2 at 10 mA cm‐2 has been achieved within the symmetrical cell. Furthermore, the full cell with NH4V4O10 cathode exhibits outstanding cyclic stability, exceeding 2000 cycles at 5 A g‐1 and maintaining a Coulombic efficiency of 100%. These new insights into anionic synergistic strategy could significantly enhance the practical application of zinc‐ion batteries.