High-donor electrolyte additive enabling stable aqueous zinc-ion batteries

The performance benefits of metallic zinc, despite many promising characteristics (such as low cost and high capacity) in rechargeable batteries, are still compromised by dendritic growth and parasitic side reactions originating from reactive aqueous electrolytes, which dramatically restrain future application. In this work, a facile strategy is proposed via introducing high-donor-number organic solvent N, N-dimethyl acetamide (DMA) as electrolyte additive to achieve high Zn reversibility. Based on multiscale theoretical and experimental investigations, it is demonstrated that high-donor DMA additive with strong electron-donating ability can confine free water activity, replace the water in Zn2+ solvation sheath, and reshape hydrogen-bonding network of water. The DMA-modified electrolyte enables remarkable suppression of water-involved hydrogen evolution and severe corrosion, which contributes to preferentially uniform deposition and ultralong cycling life of 4500 h at current density of 1 mA cm(-2) in symmetric cell, and high Coulombic efficiency of 99.6% in asymmetric cell. Coupling with VO2-based cathodes, the full battery can deliver high specific capacity of 261 mAh g(-1) at -18 degrees C and long operation stability of 500 cycles. This strategy presents a promising approach for development of high-performance aqueous metal batteries.

Automated summary

The study proposes a simple strategy to achieve high reversibility of metallic zinc in rechargeable batteries by introducing the organic solvent DMA as an electrolyte additive, which controls water activity, replaces water in Zn2+ solvation sheath, and reshapes the hydrogen-bonding network of water. This strategy enables remarkable suppression of water-involved hydrogen evolution and severe corrosion, leading to uniform deposition of zinc and long cycling life in batteries.