Vacancy and Growth Modulation of Cobalt Hexacyanoferrate by Porous MXene for Zinc Ion Batteries

Prussian blue analogues (PBAs) featuring with three-dimensional open framework are recognized as promising cathode candidates for Zinc-ion batteries, but unsatisfactory active site utilization, low conductivity and abundant structural vacancies have impeded fulfillment of their potential. In this work, a highly conductive in-plane porous MXene is for the first time adopted as a multifunctional host material to enhance cobalt hexacyanoferrate (CoHCF) growth and crystallinity. Particularly, the uniform MXene surface charges are identified to induce anisotropic and highly crystalline CoHCF, which are critical to alleviating the practical drawbacks commonly associated with the PBA family. Empowered by the targeted modification, the CoHCF nanotube on porous MXene composite realizes high surface area and low defectiveness, achieving a high capacity of 197 mAh g⁻¹ at 0.1 A g⁻¹ and robust capacity retention of 94.4% even over 3000 cycles of operation at 2.0 A g⁻¹. This composition strategy, utilizing MXene as a multifunctional template, enhances PBAs' surface area, conductivity, and crystallinity, optimizing cathode capacity and stability for ZIBs, and showcasing the potential for large-scale energy storage.<br/><br/><b>Keywords</b>: Zinc-ion battery, Porous MXene, Prussian blue analogues, induce growth, low vacancy