Dynamic Axial Ligand Dissociation Drives Solvent Trapping and Solvation-Shell Reconstruction for Ultra-Long-Life Aprotic Zinc Batteries

Abstract

Organic electrolytes can circumvent the hydrogen evolution reaction of aqueous electrolytes, but their high desolvation energy results in slow electrochemical kinetics. Here, an axial ligand dissociation mechanism guided by a dual-descriptor framework combining Mulliken charge and maximum values of electrostatic potential (ESPmax) is proposed to unlock the latent Lewis acidity in the N,N-dimethylformamide (DMF) organic electrolyte with chlorophyll-based additives (MChl). Through systematic screening of MChl spanning diverse electronic configurations and oxidation states, Ga(OH)Chl with a hydroxy axial ligand is identified as uniquely capable of spontaneous dissociation of OH–, generating a high-activity GaChl+ species with Mulliken charge (+1.32) and ESPmax (127.28 kcal mol–1). This dynamically exposed superelectrophilic center exhibits ultrastrong Lewis acidity, which competitively immobilizes the DMF solvents, reconstructing the solvated shell from Zn2+(OTf–)1.50(DMF)2.54 to Zn2+(OTf–)2.85(DMF)0.64, and accelerating the transfer kinetics of Zn2+ in the organic electrolyte. Consequently, the Zn//Zn and Zn//Cu cells exhibit long-term stability over 11000 h at 0.5 mA cm–2 (cumulative capacity of 5.5 Ah cm–2) and high Coulombic efficiency (99.6%), respectively. Furthermore, the Zn//polyaniline cell delivers a capacity retention of 80% after 700 cycles at 1 A g–1. The work establishes axial ligand dissociation as a general design concept for breaking solvation-limited kinetics in multivalent batteries.