Study of Quaternary Ammonium Additives towards High-Rate Zinc Deposition and Dissolution Cycling for Application in Zinc-Based Rechargeable Batteries

Abstract

Aqueous zinc-based rechargeable batteries, such as Zn-Ni and Zn-Air, have been increasingly re-investigated over the last decade due to the abundant and inexpensive nature of zinc, the high solubility of zinc ions, and rapid kinetics and most negative standard potential of the Zn(II)/Zn redox couple in aqueous media. However, the overwhelming challenge that has prevented the implementation of next-generation Zn batteries lies in their poor rechargeability—flowing electrolytes have proven to be of benefit to zinc deposition and dissolution cycling, but the rapid zinc deposition–dissolution at practical current densities of 100 mA cm2 or over is still questionable. Herein, we demonstrated that applying an optimal concentration of quaternary ammonium electrolyte additives with carefully selected cations’ alkyl groups can effectively improve the high-rate zinc cycling performance at 100 mA cm2/20 mAh cm2. The resultant additives significantly reduced the initial coulombic efficiency loss to only 1.11% with coulombic efficiency decay rate of 0.79% per cycle, which is less than a quarter of the benchmark of 6.25% and 3.75% per cycle for no additives.

Keywords

• zinc deposition–dissolution cycling
• quaternary ammonium salts
• electrolyte additives
• aqueous rechargeable batteries
• high charge-discharge rates