An effective descriptor for the screening of electrolyte additives toward the stabilization of Zn metal anodes

Abstract

The introduction of additives into aqueous electrolyte has great potential in suppressing dendrite growth and improving the stability of Zn anodes. However, no relevant theory or descriptor could effectively support the screening and design of suitable additives. Herein, desolvation activation energy was proposed as a critical descriptor for the screening of electrolyte additives. The effectiveness of this descriptor was proved by anionic polysaccharide additives with a low desolvation barrier. Anionic polysaccharides could spontaneously form a protective layer on the Zn anode due to the good Zn affinity, promoting the desolvation behavior through hydrogen bonding and elevating the energy barrier of H₂O dissociation. Consequently, the interfacial polarization was effectively decreased and the hydrogen evolution was inhibited, contributing to the enhanced stability of the Zn anode. As a proof of concept, pectin, one type of anionic polysaccharide was selected as the electrolyte additive for the systematic electrochemical performance studies. Significantly improved cycling stability with high reversibility, suppressed dendrite growth and low overpotential was achieved in the symmetric Zn cells.