Competitive Coordination Structure Regulation in Deep Eutectic Electrolyte for Stable Zinc Batteries

Abstract

Rechargeable zinc‐based batteries are finding their niche in energy storage applications where cost, safety, scalability matter, yet they are plagued by rapid performance degradation due to the lack of suitable electrolytes to stabilize Zn anode. Herein, we report a competitive coordination structure to form unique quaternary hydrated eutectic electrolyte with ligand‐cation‐anion cluster. Unraveled by experiment and calculation results, the competing component can enter initial primary coordination shell of Zn2+ ion, partially substituting Lewis basic eutectic ligands and reinforcing cation‐anion interaction. The hydration‐deficient complexes induced between competing eutectic as hydrogen bond donor‐accepter and water also broaden the electrochemical window and confine free water activity. The altered coordination further leads to robust hybrid organic‐inorganic enriched solid electrolyte interphase, enabling passivated surface and suppressed dendrite growth. Noticeably, stable Zn plating/stripping for 8000 cycles with high Coulombic efficiencies of 99.6% and long cycling life of 10000 cycles for Zn‐organic batteries are obtained. Even under harsh conditions (small N/P ratio, low temperature), the profits brought by the competitive eutectic electrolyte are still very prominent. This design principle leveraged by eutectic electrolytes with competitive coordination offers a new approach to improve battery performance.

Recent advances in zinc-ion dehydration strategies for optimized Zn–metal batteries

“…1,6-Hexanediol (HDO) was applied as a competitive additive in the hydrated ZnCl 2 /Ace system (HZAH-0) to develop a quaternary hydrated DES electrolyte (HZAH-1). 139 The change in the solvation structure of the HDO-containing electrolyte could be characterized by WT-EXAFS (Fig. 11c), which indicates that HBO could substitute Ace partially, leading to a longer Zn–O coordination radius.…”

“…ZnCl 2 could serve as a strong Lewis acid to build low-cost ZEEs. 137–142 Tao et al introduced a small amount of water in ZnCl 2 /acetamide (Ace) (ZES) to decrease the viscosity and promote the Zn deposition process. 138 As shown in the 17 O NMR spectra in Fig.…”