Electrodeposited zeolitic imidazolate framework-8 modified zinc anode supported over porous copper structure for rechargeable aqueous zinc-ion batteries

Abstract

Electrodeposition technique is used to create a protective layer of zeolitic imidazolate framework-8 (ZIF-8), a metal–organic framework (MOF), over the zinc–copper (Zn–Cu) structure, forming an efficient anode (ZIF-8/Zn–Cu) for aqueous zinc-ion batteries (ZIBs). The utilization of the ZIF-8 layer extends the battery life in symmetric cell configurations up to 1000 hours at 0.5 mA cm⁻². In comparison, pristine Zn suffers a sudden voltage drop due to a short circuit after 169 hours, and the Zn–Cu anode fails after 853 hours. Post-cycled anode characterization studies and mathematical modelling, by incorporating the Zn²⁺ transport model with the electrochemical reaction model, revealed that the ZIF-8 layer minimizes Zn dendrites, enhancing the cycle life of ZIBs. The full-cell configuration, ZIF-8/Zn–Cu//α-MnO₂, exhibits excellent cycling performance at various C-rates (0.4C to 4C), delivering an initial discharge capacity of 204.02 mAh g⁻¹ at 0.4C (1C = 820 mA g⁻¹) and retaining 92.62% of its capacity after 1200 charge–discharge cycles. At a higher C-rate of 4C, ZIF-8/Zn–Cu//α-MnO₂ delivers an initial discharge capacity of 64.12 mAh g⁻¹ with 85.56% discharge capacity retention after 3000 cycles. This study broadens ZIF-8 MOF applications in ZIBs and paves the way for developing stable MOF-based anodes for next-generation electrochemical energy storage systems.