Tuning the Solvation Structure in Aqueous Zinc Batteries to Maximize Zn-Ion Intercalation and Optimize Dendrite-Free Zinc Plating


Aqueous zinc batteries are recognized to suffer from H$^+$/Zn$^{2+}$ coinsertion in the cathode, but few approaches have been reported to suppress deleterious H+ intercalation. Herein, we realize this goal by tuning the solvation structure, using LiV$_2(PO_4)_3$ (LVP) as a model cathode. Phase conversion of LVP induced by H+ intercalation is observed in 4 m Zn(OTf)$_2$, whereas dominant Zn2+ insertion is confirmed in a ZnCl2 water-in-salt electrolyte (WiSE). This disparity is ascribed to the complete absence of free water and a strong Zn$^{2+}$–H$_2$O interaction in the latter that interrupts the H2O hydrogen bonding network, thus suppressing H+ intercalation. On the basis of this strategy, a novel PEG-based hybrid electrolyte is designed to replace the corrosive ZnCl$_2$ WiSE. This system exhibits an optimized Zn$^{2+} solvation sheath with a similar low free water content, showing not only much better suppression of H+ intercalation but also highly reversible Zn plating/stripping with a CE of ∼99.7% over 150 cycles.

ACS Energy Letters
Ryan Kingsbury, Ph.D., P.E.
Ryan Kingsbury, Ph.D., P.E.
Assistant Professor

Ryan is an engineer and scientist working to accelerate development of advanced materials for water purification and clean energy production.