γ-valerolactone/water hybrid electrolyte enabled long-duration zinc ion batteries

Abstract

Aqueous zinc-ion batteries (ZIBs) are promising for large-scale energy storage. However, practical exploitation of ZIBs is hampered by several challenges such as dendrite growth and inferior Coulombic efficiency (CE) of Zn anode, and poor cyclability of cathode at low rate. Here we report a novel hybrid electrolyte with γ-valerolactone (VA) as the co-solvent to solve the above problems. This hybrid electrolyte not only enables Zn anode with exceptional reversibility and long lifespan (average CE of 99.77 % in asymmetric cell and cycle life of 2210 h in symmetric cell at 0.5 mA cm⁻² and 0.5 mAh cm⁻²) but also endows the full-cell with unprecedently cycling stability at harsh low rate (96 % capacity retention after 300 cycles at 0.22 C, running time over 2600 h). The distinguished compatibility of the as-designed electrolyte is ascribed to its capability to modulate homogeneous and dendrite-free Zn deposition concomitant with the significantly decreased water activity. Moreover, the as-prepared hybrid electrolyte also shows good temperature adaptability, which can stably work at -20 ℃. This work provides new insights into electrolyte modulation via the co-solvent strategy for high-performance and long-duration ZIBs.