Boosting Zn||I2 Battery’s Performance by Coating a Zeolite-Based Cation-Exchange Protecting Layer

Abstract

The intrinsically safe Zn||I₂ battery, one of the leading candidates aiming to replace traditional Pb-acid batteries, is still seriously suffering from short shelf and cycling lifespan, due to the uncontrolled I₃⁻-shuttling and dynamic parasitic reactions on Zn anodes. Considering the fact that almost all these detrimental processes terminate on the surfaces of Zn anodes, modifying Zn anodes’ surface with protecting layers should be one of the most straightforward and thorough approaches to restrain these processes. Herein, a facile zeolite-based cation-exchange protecting layer is designed to comprehensively suppress the unfavored parasitic reactions on the Zn anodes. The negatively-charged cavities in the zeolite lattice provide highly accessible migration channels for Zn²⁺, while blocking anions and electrolyte from passing through. This low-cost cation-exchange protecting layer can simultaneously suppress self-discharge, anode corrosion/passivation, and Zn dendrite growth, awarding the Zn||I₂ batteries with ultra-long cycle life (91.92% capacity retention after 5600 cycles at 2 A g⁻¹), high coulombic efficiencies (99.76% in average) and large capacity (203–196 mAh g⁻¹ at 0.2 A g⁻¹). This work provides a highly affordable approach for the construction of high-performance Zn-I₂ aqueous batteries.