Tailored ZnF₂/ZnS-rich interphase for reversible aqueous Zn batteries

The urgent need for highly safe and sustainable large-scale energy storage systems for residential buildings has led to research into aqueous zinc ion batteries. However, when zinc is used in aqueous zinc ion batteries, it suffers from severe irreversibility due to its low Coulombic efficiency, dendrite growth, and side reactions. To address these challenges, we take advantage of organic cation to induce trifluoromethanesulfonate decomposition to build zinc fluoride/zinc sulfide-rich solid electrolyte interphase (SEI) that not only can adapt to a high areal capacity of deposition/stripping disturbance but also adjust zinc ion deposition path to eliminate dendrite. As a result, the unique interface can promote the Zn battery to achieve excellent electrochemical performance: high levels of plating/stripping Coulombic efficiency (99.8%), stability life (6,600 h), and cumulative capacity (66,000 mAh·cm⁻²) at 68% zinc utilization (20 mAh·cm⁻²). More importantly, the SEI significantly enhances the cyclability of full battery under limited Zn, lean electrolyte, and high areal capacity cathode conditions.