In situ oxidation coating of copper bismuth oxide with polypyrrole to construct rice-like core-shell structures: Revealing prospects for high-performance asymmetric supercapacitor anodes

Enhancing the energy density of asymmetric supercapacitors (ASCs) requires developing high-performance anode materials that pair well with cathode materials. In this study, rice-like structured CuBi₂O₄ was synthesized using a simple and cost-effective wet-chemical method. Subsequently, the conductive polymer polypyrrole (PPy) was polymerized on the surface of CuBi₂O₄. This process yielded a novel core-shell structured anode material (CuBi₂O₄@PPy). Due to its unique composition and structure, CuBi₂O₄@PPy exhibits remarkable electrochemical properties. For example, it delivers a specific capacitance of 1336 F·g^-1 at 1 A·g^-1. When paired with Ni_1.5Co_1.5S₄ (NCS) as the cathode material, the NCS//CuBi₂O₄@PPy ASC demonstrates a specific capacitance of 219.2 F·g^-1 at 1 A·g^-1. The device achieves an energy density of 68.5 Wh·kg^-1 at a power density of 750 W·kg^-1. Additionally, the NCS//CuBi₂O₄@PPy ASC can power commercial LED bulbs for over 25 min. Overall, as an anode material, the core-shell structured CuBi₂O₄@PPy holds great promise for the development of high-performance electrochemical energy storage devices.