Zn-Rejuvenated and SEI-Regulated Additive in Zinc Metal Battery via the Iodine Post-Functionalized Zeolitic Imidazolate Framework-90

Abstract

Due to the high abundance of their components, low cost, and high safety, zinc-based batteries open up new vistas for large-scale energy storage. However, their stability, lifetime, and reversibility are impaired by passivation and dendrite growth of the Zn anode. Here, this challenge is circumvented by an iodine post-functionalized zeolitic imidazolate framework-90 (ZIF-90-I) additive, in which the polycation absorbed on Zn anode can regulate solid–electrolyte interphase (SEI) formation in the 1 m Zn(TFSI)<inf>2</inf> electrolyte and induce Zn²⁺ uniform deposition. Moreover, the I<inf>3</inf>⁻/I⁻ redox can rejuvenate dead Zn and inhibit dendrites. With the ZIF-90-I additive, Zn plating/stripping at 99.5% Coulombic efficiency for 120 cycles is obtained in Zn||Ti cells at 20 mA cm⁻²/1 mAh cm⁻². In addition, Zn||Zn cells show steady cycling for 1200 h at 5 mA cm⁻²/1 mAh cm⁻² with stable overpotentials. The utilization rate of Zn reaches up to 68.6%. In situ optical microscopy reveals smooth, uniform Zn plating, and the Zn-rejuvenated function from the I³⁻/I⁻ redox couple. The refreshed SEI with the increase of Zn-rich complexes, and nitrides from adsorbed polycations, are uniform and ZnF<inf>2</inf>-rich in the Zn(TFSI)<inf>2</inf> + ZIF-90-I electrolyte. The full Zn||air cells in Zn(TFSI)<inf>2</inf> + ZIF-90-I electrolyte exhibit excellent cycling stability with stable polarization voltage at 0.1 mA/0.05 mAh cm⁻².