Cellulose-complexing strategy induced surface regulation towards ultrahigh utilization rate of Zn

Abstract

Electrolyte design provides a fundamental solution to address the irreversibility and instability of metallic Zn anodes for the fast-developing zinc-ion batteries, considering the increasing issue of their sustainability. Herein, a cellulose-complexing approach was developed for a ZnCl₂-based eutectic electrolyte to reconstruct Zn²⁺ coordination, tune water activity and regulate the solid–electrolyte interface (SEI). In the case of deficient water, the oxygen atoms from the glucose unit were revealed to coordinate directly with Zn²⁺, resulting in the participation of cellulose in the solvation shell of Zn²⁺, with a change in the hydrogen-bond network, where water transformed into the bulk state. The reshaped Zn²⁺ coordination with sluggish water activity led to a widened electrochemical window and promising ion transport in the complex electrolyte. Endowed with a dissolution–regeneration induced in situ SEI with inorganic–organic characteristics, dendrite-free Zn stripping/plating were achieved at a high current density of 50 mA cm⁻² and 50 mA h cm⁻² for 2000 h, with a high depth-of-discharge of 85%. The complex electrolyte was demonstrated to be beneficial for the long-term cycling stability of the activated carbon/Zn cell compared to its ZnCl₂ eutectic electrolyte counterpart. Further, an artificial SEI was fabricated via electrochemical deposition using the electrolyte, possessing the merits of organic-dominant characteristics. The developed approach provides a facile route to prepare novel zinc electrolytes towards a high utilization rate of Zn.