Preparation and application of a flower-rod-like Bi₂S₃/Co₃O₄/rGO/nickel foam supercapacitor electrode

Herein, we have prepared a new nanocomposite Bi2S3/Co3O4/rGO/Ni foam substrate electrode through hydrothermal synthesis and an annealing process. SEM clearly shows that the Bi2S3/rGO/Ni foam substrate and Co3O4/rGO/Ni foam substrate prepared under the experimental conditions are cuboid-shaped and flower-shaped, respectively. However, the shape of Bi2S3/Co3O4/rGO/Ni foam is a perfect combination of the above two. We call this cuboid full of petals a flower-rod-like shape. The BET test found that the specific surface area of this unique morphology is as high as 152.7 cm2 g-1, which is beneficial towards charge transfer and improves the overall electrochemical reaction performance of the electrode. In addition, electrochemical performance tests displayed that the Bi2S3/Co3O4/rGO/Ni foam electrode had a high specific capacitance of 2214.3 F g-1 at 1 A g-1. The highest energy density of the Bi2S3/Co3O4/rGO/Ni foam//activated carbon asymmetric supercapacitor is 133.4 W h kg-1 (the corresponding power density is 800.1 W kg-1), and the highest power density is 8568.2 W kg-1 (the corresponding energy density is 70.5 W h kg-1). Additionally, under the condition of 10 A g-1 current density, the capacitance retention rate is still extremely high: 99.4% after 10 000 continuous charge and discharge tests. In practical application, two Bi2S3/Co3O4/rGO/Ni foam//activated carbon asymmetric supercapacitors in series can make a 2.5 V bulb maintain a high brightness for 1 minute.