Ion-Framework Electrolyte Featured Zinc-Ion Transport for Solvent and Interphasial Co-Passivation.

Abstract

The rapid application of zinc-ion (Zn²⁺) energy storage lacks favorable solvation structures to simultaneously form inert electrolyte environments and robust solid electrolyte interphase (SEI), which means that Zn²⁺ devices cannot synchronously against the side reactions, Zn dendrites and narrow electrochemical stability windows, further hindering their wide operative voltage window and ultra-long service life. Here, ion-framework electrolytes are designed by using large-sized inert-ammonium salts as the main solute. The ion framework, assembled from ultra-large solvation ion clusters containing large tetraethylammonium cations, large anions, and abundant solvents via electrostatic interactions, not only forms suitable channels for Zn²⁺ transport but also constrains free solvents to passivate their electrochemical activity, achieving an ultra-wide electrochemical stability window about 3.72 V. More importantly, the enrichment of the ion framework at Zn interface generates a homogenous SEI with the dense polymer-inorganic hybrid structure to passivate the interphasial chemistry, which eliminates the Zn dendrites and side reactions. Therefore, Zn anode using this electrolyte achieves the ultra-long cycling stability of 8,150 h, and Zn metal||activated carbon capacitors exhibit a high operative voltage (0-2.1 V) and ultra-long cycle life (≈170,000 cycles at 10 A g^-1). This electrolyte design principle is promising for addressing the typical challenges in other metal-ion systems.