Suspension Electrolytes with Catalytically Self-Expediating Desolvation Kinetics for Low-Temperature Zinc Metal Batteries

Abstract

The conventional electrolyte for rechargeable aqueous zinc metal batteries (AZMBs) breeds many problems such as Zn dendrite growth and side reaction of hydrogen evolution reaction, which are fundamentally attributed to the uneven ion flux owing to the high barriers of desolvation and diffusion of Zn[(H₂O)₆]²⁺ clusters. Herein, to modulate the [Zn(H₂O)₆]²⁺ solvation structure, the suspension electrolyte engineering employed with electron-delocalized catalytic nanoparticles is initially proposed to expedite desolvation kinetics. As a proof, the electron-density-adjustable CeO_2-x is introduced into the commercial electrolyte and preferentially adsorbed on the Zn surface, regulating the Zn[(H₂O)₆]²⁺ structure. Meanwhile, the defect-rich CeO_2-x redistributes the localized space electric field to uniformize ion flux kinetics and inhibits dendrite growth, as confirmed by a series of theoretical simulations, spectroscopical and experimental measurements. Encouragingly, the CeO_2-x decorated suspension electrolyte enables a long stability over 1200 cycles at 5 mA cm⁻² and an extended lifespan exceeding 6500 h with lower overpotentials of 34 mV under 0 °C. Matched with polyaniline cathodes, the full cells with suspension electrolyte exhibit a capacity-retention of 96.75% at 1 A g⁻¹ under −20 °C as well as a long lifespan of up to 400 cycles in a large-areal pouch cell, showcasing promising potentials of suspension electrolyte for practical AZMBs.