Mn–Co Prussian blue analogue cubic frames for efficient aqueous Zn ion batteries

Abstract

Mn based Prussian blue analogs (PBAs) have emerged as highly promising cathode materials for aqueous zinc-ion batteries (AZIBs), owing to their high specific capacity and operating potential. However, the cycling stabilities of these materials remain unsatisfactory because their structural deformation induces ion intercalation. In this study, a PVP assisted Mn–Co-PBA was synthesized using a simple hydrothermal method. Mn–Co-PBA displays unique cubic frame-like structures with a high specific surface area and fewer zeolitic water molecules in the host lattice. The Mn–Co-PBA||Zn cell displayed an excellent specific capacity of 138 mAh g−1 at 0.1 A g−1, good rate capability (95 mAh g−1 at 1 A g−1), and good cycling stability (capacity retention of 92.8% after 1000 cycles) because of its unique cubic frame structure. This structure can provide a greater number of Zn diffusion pathways and alleviate the structural strain during Zn2+ ion insertion/extraction processes. An ex-situ XRD analysis revealed that the de/intercalation of Zn2+ ions in the Mn–Co-PBA electrodes was highly reversible. These results show that Mn–Co-PBA holds great promise for advancement in the field of AZIBs and contributes to the realization of effective and sustainable battery technologies.