Enhancing Aqueous Zinc Sulfur Battery Performance with a Novel Hybrid Electrolyte

Rechargeable aqueous Zn/S batteries hold significant promise due to their high capacity and energy density. However, their long-term cycling stability is hindered by sulfur side reactions and the growth of Zn anode dendrites in the aqueous electrolyte. In response, this research explores a simultaneous solution to these challenges through the development of a unique hybrid aqueous electrolyte incorporating ethylene glycol as a co-solvent. This innovative electrolyte design strategy facilitates the fabrication of Zn/S batteries with exceptional performance metrics on capacity, energy density and cycling stability under a high current rate. In addition, the investigation of the cathode charge-discharge mechanism reveals a multi-step conversion reaction. During discharge, elemental sulfur undergoes sequential reduction by Zn, ultimately forming ZnS. On charging, ZnS and short-chain polysulfides are oxidized back to elemental sulfur. This study not only offers a novel electrolyte design approach but also sheds light on the unique multi-step electrochemistry of the Zn/S system, paving the way for improved Zn/S batteries in the future.