Achieving Highly Reversible Zn Anodes by Inhibiting the Activity of Free Water Molecules and Manipulating Zn Deposition in a Hydrogel Electrolyte

Abstract

Zinc metal anodes have been widely used in aqueous Zn-ion batteries. However, side reactions and zinc dendrites were generated on the Zn anode during cycling. These problems lead to short circuits and poor long-cycle stability of the battery. This paper reports a multiple cross-linked PAM-CMC-GG (PCG) gel electrolyte. Zinc uniformly deposited on (002) crystal surfaces under the combined effect of carboxylic acid and amide groups in PCG gel electrolyte. The behavior effectively reduces the generation of zinc dendrites. In addition, the abundant hydroxyl groups in PCG can inhibit the activity of free water and reduce the generation of solvent structures, thus suppressing the formation of byproducts. As a result, the symmetric cells assembled with PCG gel electrolyte operated stably for over 450 h at a current density of 5 mA cm–2, and Zn/Cu asymmetric cells maintained a coulomb efficiency (CE) of 99.2% for more than 500 cycles. It is expected that PCG gel electrolyte provides promising prospects for the practical application of gel electrolytes in energy storage devices.