A low fraction electrolyte additive as interface stabilizer for Zn electrode in aqueous batteries

The electrochemical performance of Zn metal anode in aqueous batteries is challenged by serious parasitic reactions and dendrite growth. Herein, we introduce an interface stabilizer of 2,3,4,5-tetrahydrothiophene-1,1-dioxide (TD), with a low volume fraction of 0.5%, in the 3 m ZnSO4 electrolyte for zinc batteries. Theoretical calculations and experimental analysis confirm the adsorption of TD molecules on Zn surface, which inhibits the spontaneous chemical corrosions by mildly acidic electrolytes and ensures a homogeneous electrode surface. The adsorbed TD further induces a stable solid-electrolyte interface (SEI) composed of organic sulfone/sulfonate species and inorganic zinc salts. The parasitic reactions are further suppressed. Meanwhile, the Zn2+ flux is homogenized in SEI, and uniform Zn deposition is realized. In the ZnSO4 electrolyte with 0.5% TD additive, stable Zn plating-stripping is achieved for 2500 h at 5 mA cm−2 and 2 mAh cm−2, which is 20 times longer than in the TD free electrolyte. Moreover, the Zn//V6O13·H2O full batteries with limited anode of N/P = 4 and N/P = 1.3 realize 93.8% and 75.0% capacity retentions, respectively, after 200 cycles with the 0.5% TD electrolyte, superior to 74.3% and 43.6% with the TD free electrolyte. Our work presents an effective strategy to promote the stability of Zn electrode for high performance aqueous batteries.