In Situ Modification of Sulfur-Based Cathode Electrolyte Interphases for Boosting Zinc/Graphite Dual-Ion Batteries via Vinylene Carbonate Additive and Dipropylene Glycol Methyl Ether/Water Mixed Solvent

Dual-ion batteries (DIBs) have been extensively explored due to their low material costs, high power density, and eco-friendly characteristics. However, the graphite cathode often leads to structural damage and instability at the electrode/electrolyte interface, severely diminishing its electrochemical performance. This work presents a cost-effective approach from the perspective of electrolyte optimization to overcome these challenges. By incorporating a moderate amount (5 wt %) of vinylene carbonate (VC) as an additive into a mixed solvent of dipropylene glycol methyl ether (DPM) and water, significant improvements in electrochemical performance are achieved, primarily due to the formation of a sulfur-rich cathode electrolyte interface (CEI) on the graphite surface and the electrolyte additive fostering the generation of nanosized sulfide particles in the graphite lattice, which provide active storage sites for anions. In the graphite-Zn DIB, a high discharge-specific capacity of 140 mAh g-1 was achieved at 100 mA g-1, and after 500 cycles, the capacity retention rate is 84.2%, which is much higher than that of the battery without VC. This work demonstrates the potential of a cost-effective electrolyte in optimizing the composition of the graphite cathode CEI and promoting the formation of inorganic nanoparticle hosts on the graphite cathode surface for enhancing the performance of DIBs.