Boosting Zn electrode reversibility in aqueous electrolyte using low-cost antisolvents

Abstract

Antisolvent addition has been widely studied in crystallization in the pharmaceutical industries by breaking the solvation balance of the original solution. Here we report a similar antisolvent strategy to boost Zn reversibility via regulation of the electrolyte on a molecular level. By adding for example methanol into ZnSO 4 electrolyte, the free water and coordinated water in Zn 2+ solvation sheath gradually interact with the antisolvent, which minimizes water activity and weakens Zn 2+ solvation. Concomitantly, dendrite-free Zn deposition occurs via change in the deposition orientation, as evidenced by in situ optical microscopy. Zn reversibility is significantly boosted in antisolvent electrolyte of 50% methanol by volume (Anti-M-50%) even under harsh environments of -20 °C and 60 °C. Additionally, the suppressed side reactions and dendrite-free Zn plating/stripping in Anti-M-50% electrolyte significantly enhance performance of Zn/polyaniline coin and pouch cells. We demonstrate this low-cost strategy can be readily generalized to other solvents, indicating its practical universality. Results will be of immediate interest and benefit to a range of researchers in electrochemistry and energy storage.