Carbon-Supported Medium-Entropy Perovskite Fluoride Nanocomposite as a Pseudocapacitive Cathode for Advanced Aqueous Zinc Batteries

The development of high-performance cathode materials for aqueous zinc batteries (AZBs) is of great significance for the practical application of AZBs in large-scale energy storage. Here, a medium-entropy Ni–Co–Zn–Mn multimetal perovskite fluoride was adhered on carbon nanotubes/nanoparticles (denoted as KNa-NCZMF-CNTs and KNa-NCZMF-CNPs, respectively) via a solvothermal method and employed as pseudocapacitive cathode materials in AZBs. Owing to the synergistic effects of the multiple constituent elements and the enhanced conductivity provided by the carbon-based composites, the KNa-NCZMF-CNPs material exhibits exceptional electrochemical performance in both three-electrode and two-electrode configurations. In a three-electrode system, a specific capacitance of up to 382 C g–1 is achieved at a current density of 1 A g–1. When assembled into a two-electrode full cell with a zinc foil anode, the device delivers an energy density of 117.02 Wh kg–1 at a power density of 1.54 kW kg–1. The charge-storage conversion mechanism, involving the transformation of ABF3 nanocomposites into metal oxides and hydroxides in an alkaline electrolyte, was elucidated by X-ray photoelectron spectroscopy (XPS). This work provides profound insights into the charge-storage behavior and structure–activity relationships of medium-entropy, multimetal perovskite cathodes in aqueous zinc battery systems and offers a strategy for constructing high-performance AZBs.