Metal-organic polyhedrons modulated eccentric solvation sheath enables fast charge transfer kinetics in nonaqueous Zn electrolytes

Abstract

Zn batteries emerge as a promising class of energy storage devices with high energy density, low cost and high safety. Nonaqueous Zn electrolytes offer high interfacial stability yet suffer from sluggish interfacial charge transfer kinetics. Here, we report an eccentric Zn²⁺ solvation structure enabled by metal-organic polyhedrons (MOPs) in nonaqueous colloidal electrolytes, which facilitates charge transfer at electrode-electrolyte interface. The resultant Zn²⁺(ZrT)(DMF)₁ solvation structure features a large solvation sheath and a small ion-to-electrode distance, thus reducing the energy required for reorganizing the solvation sheath to accept electron. As a result, the MOPs-modulated colloidal electrolyte enables Zn anode with supreme stability for over 1200 h at 8 mA cm⁻² and 270 h at 12 mA cm⁻², along with high coulombic efficiency (∼99.8 % over 1000 cycles), notably exceeding the performance of conventional aqueous and nonaqueous electrolytes. The design principle of solvation sheath might be broadly applicable to other high-valence metal cation batteries.