Manipulating Interfacial pH by the Base-Catalyzed Hydrolysis Strategy for Highly Reversible Zinc Anodes

Abstract

The concentrated hydroxide ions (OH − ) resulting from the hydrogen evolution reaction gives rise to substantial challenges for the Zn anode/ electrolyte interface, including proliferating byproducts and severe dendrite growth. Herein, methyl acetate (MA) additive is proposed to eliminate the crippling OH − , hence manipulating interfacial pH and alleviating accumulation of byproducts. Raman spectra and FTIR analysis elucidate the underlying mechanism of the hydrolysis reaction, which means attacked carbonyl corresponding to the elimination of OH − . In situ pH monitoring verifies availably inhibited OH − concentration with MA additive. From multidimension analysis, the base-catalyzed hydrolysis strategy can significantly protect Zn anode from deterioration during "shelf life" contributing to following superior Zn plating/stripping. Consequently, with MA additive, the pH is stabilized at a lower level of 5.11. Zn plating/stripping achieves a conspicuous cycle life of 2000 h (2.0 mA cm −2 with 2.0 mA h cm −2 ). Even after "shelf life", Zn||Zn symmetric cells deliver an impressive cycling stability of 700 h compared to the counterpart of 22 h in ZnSO 4 . Zn||MnO 2 /CNT pouch cells with a high mass loading cathode of ∼8 mg cm −2 exhibit a stable lifespan of 100 cycles at 1 C. This work demonstrates a hydrolysis strategy to manipulate interfacial pH and stabilize the interface for the reversible Zn anode.