Artificial solid electrolyte interphase for thermally stable rechargeable aqueous zinc batteries

Abstract

Rechargeable aqueous zinc battery (RAZB) represents a promising energy storage system for its high energy density, high safety and low-cost. Among available cathode materials for RAZBs, vanadium oxide (V2O5) is being considered thanks to its high specific discharge capacity, and the ease of Zn intake/extraction due to layered crystalline structure. However, V2O5 is unstable during charge and discharge processes in aqueous batteries. To address this issue, we introduce a surface modification method to form artificial solid electrolyte interphase (SEI) on the V2O5 particles before used in the battery. The artificial SEI layer, which is composed of conductive heterocyclic aromatic chains, protects the active material from direct contact with the aqueous electrolyte. Surprisingly, the ultrathin artificial-SEI benefits V2O5 to display a high capacity of 195.7 mAh·g−1 (at current density of 1 A g−1) with just 9.5% capacity decay at room temperature after 200 cycles. Under elevated temperature (60 °C), the RAZB still shows an outstanding 80.1% capacity retention after 150 cycles (at current density of 1 A g−1) vs. 25% retention of the bare V2O5 material. Overall, the use of artificial-SEI offers a new approach to realize a thermal stable energy storage system, which is considered an alternative to lithium-ion batteries.