Examining Concentration‐Reliant Zn Deposition/Stripping Behavior in Organic Alcohol/Sulfones‐Modified Aqueous Electrolytes

Abstract

The practical application of Zn metal anodes in electronic devices is hindered by dendrite growth and parasitic reactions. Electrolyte optimization, particularly the introduction of organic co‐solvents, is widely used to circumvent these challenges. Various organic solvents in a wide range of concentrations have been reported; however, their influences and corresponding working mechanisms at different concentrations are largely unexplored in the same organic species. Herein, economical, low‐flammable ethylene glycol (EG) is used as a model co‐solvent in aqueous electrolytes to examine the relationship between its concentration, anode‐stabilizing effect, and mechanism. Two maximal values are observed for the lifetime of Zn/Zn symmetric batteries under EG concentrations from 0.05 vol% to 48 vol%. Zn metal anodes can stably run for over 1700 h at a low EG content (0.25 vol%) and high EG content (40 vol%). Based on the complementary experimental and theoretical calculations, the enhancements in low‐ and high‐content EG are ascribed to the specific surface adsorption for suppressed dendrite growth and the regulated solvation structure for inhibited side reactions, respectively. Intriguingly, a similar concentration‐reliant bimodal phenomenon is observed in other low‐flammable organic solvents (e.g., glycerol and dimethyl sulfoxide), thereby suggesting universality of this study and providing insight into electrolyte optimization.

Mitigating cathodic dissolution through interfacial water masking to enhance the longevity of aqueous zinc–ion batteries

“…This advantageous dispersion of interfacial ionic fluxes fosters lateral growth and uniform deposition. 40,41…”

Highly Potent and Low‐Volume Concentration Additives for Durable Aqueous Zinc Batteries: Machine Learning‐Enabled Performance Rationalization

“…The corresponding voltage–capacity profiles for G) additive‐free and H) 1% Butandiol electrolyte cells at 2 mA cm −2 and 2 mAh cm −2 with 10 µm Zn. I) The comparison of cumulative plated capacity, electrolyte to capacity (E/C) ratio, Zn utilization, separator thickness, and additive concentration with other reported low‐concentration organic additives [ 33–35 ] and in situ SEI [ 22,25,36,37 ] constructing electrolyte additives.…”

“…Nonetheless, the remarkable long‐term zinc cycling reversibility exhibited under high Zn utilization, low E/C ratio, and thin separator, achieved with the low concentration (1 vol%) of the butanediol additive, exceeds the performance of nearly all previous additive‐based research works. [ 22,25,33–37 ]…”