Examing Competitive Coordination Structure in Eutectic Electrolyte for Zinc-Ion Batteries

Designing next-generation alternative energy storage devices that feature high safety, low cost, and long operation lifespan is of the utmost importance for future wide range of applications. Aqueous zinc-ion batteries play a vital part in promoting the development of portability, sustainability, and diversification of rechargeable battery systems. Based on the theory of electrolyte solvation chemistry, deep understanding of interaction between electrolyte components and their impact on the chemical properties have significant influence on revitalizing the rechargeable zinc-ion batteries field. Characterized by intermolecular forces and tunable compositions, reorganized ligand-oriented solvation shell in eutectic system can bring potential benefits for Zn plating/stripping. Instead of forming [Zn(H 2 O) 6 ] 2+ , the use of organic ligands in deep eutectic solvent electrolytes will allow the formation of multiple Zn coordination. In this case, we tentatively propose a plausible strategy to induce competing organic ligand for original eutectic electrolyte. The competing eutectic ligands enter coordination structure, weakening original interaction and form hydration-deficient complexes. The presence of competing agent enables the enhanced cation-anion binding. Building upon the competitive coordination, four-coordinated ligand-cation-anion cluster enables broadened electrochemical window, shielded active water and enhanced zincophilicity. The altered coordination further leads to robust hybrid organic-inorganic enriched solid electrolyte interphase, enabling passivated surface and suppressed dendrite growth. The in-depth mechanism is demonstrated by a series of excellent performance with high Coulombic efficiency and long working life. This design principle leveraged by eutectic electrolytes with competitive coordination offers a new approach to improve battery performance.