Bi Mediated Growth of Bi2o3@Bi2o2co3 Heterostructure Electrode for Significant Enhancement of Electrochemical Capacity

Bi2O3 is considered a promising material for pseudocapacitance due to its high theoretical specific capacitance, but poor inherent conductivity and poor ion diffusion limit its actual capacitance. Therefore, the rational design of the surface and structure of Bi2O3 is the key to use to improve the specific capacitance of Bi2O3. Here, we report the fabrication of high-performance negative electrodes from Bi2O2CO3 nanosheets wrapped around Bi2O3 arrays (Cu foam@Bi2O3@Bi2O2CO3) by a combination of electrical substitution, oxidative calcination and hydrothermal methods. The realized Cu foam@Bi2O3@Bi2O2CO3 presents a surface cross-linked laminar structure, which shortens the electrolyte penetration path. The direct replacement growth of Bi on copper substrates to obtain subsequent composites can greatly enhance the electron transfer between the active material and the collector and achieve ultra-high loadings (13.2 mg cm-2). Thus, the electrode exhibits an ultra-high areal capacitance of 16.5 mA h cm-2 at 10 mA cm−2. Remarkably, maximum energy density of 1.6 mW h cm-2 (45.5 W h Kg-1) is achieved for the constructed asymmetric supercapacitor device at a power density of 6.2 mW cm-2 (175.9 W Kg-1). This study provides a new strategy for the development and design of high-performance electrodes for energy conversion and storage.