Sulfurized Composite Interphase Enables a Highly Reversible Zn Anode

Abstract

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.