From PBA nanocubes to octa-truncated cubes: The ammonium oxalate etching route for enhanced performance in aqueous Ni-Zn batteries

Prussian blue analogs (PBAs) are regarded as highly promising cathode materials for nickel-zinc batteries (NZBs) due to their simple preparation process and stable framework structure. However, their practical application remains limited by poor capacity retention and cycling stability. In this study, a chemical etching strategy using ammonium oxalate as the etchant was employed to transform nanocube structures into octahedrally truncated cubes. This defect engineering approach effectively enhanced the rate capability and cycling performance of the material. As a cathode material for NZBs, NiCoHCF-1.2 (where 1.2 refers to the sample prepared using 1.2 g of ammonium oxalate) demonstrated an outstanding peak power density (31.83 mW·cm⁻²) and retained 63.29% of its capacity after 1000 cycles. This research provides a viable pathway for constructing novel nanostructured PBA materials and holds significant importance for advancing the development of advanced energy storage systems.