Constructing Dynamic Cross-Linking Networks as Durable Bifunctional Coating for Highly Stable Zinc Anodes.

Abstract

The serious dendrite growth and H2O-induced side reactions on the Zn electrode lead to a significant fading in the cycling performance, hindering the development of commercial applications of aqueous Zn-ion batteries (AZIBs). Herein, a novel bifunctional network coating of dynamically cross-linking sodium alginate with trehalose has been rationally constructed on the Zn anode (Zn@AT). Firstly, the AT coating possesses abundant zinophilic oxygen-containing functional groups, which are able to induce uniform Zn2+ ion flux. Secondly, the AT coating as a solid barrier can effectively inhibit H2O-induced side reactions by lowering the activity of H2O molecules. More specially, based on the dynamic cross-linking, AT network coating is endowed with self-healing capacity during cycling for durable battery operation. Consequentially, Zn@AT anodes in symmetric cells can cycle stably for 2787 h at 2 mA cm-2/2 mAh cm-2, and even achieve a significantly long cycle performance of 1087 h at large charge/discharge depths of 10 mA cm-2/10 mAh cm-2. Moreover, the Zn@AT//MnO2 full cell shows excellent specific capacity of 175 mAh g-1 after 400 cycles. This study lights an effective strategy to enhance the durability of Zn electrodes in AZIBs.