Preparation And Supercapacitor Performance Of The Cobalt-based Metal Sulphide Electrode Materials

The performance of electrode materials directly determines the energy storage performance of supercapacitors,so the use of a facile method to synthesise novel electrode materials is of great importance to improve the energy storage performance of supercapacitors.In this thesis,the electrochemical performance of cobalt sulphide electrode materials was enhanced by preparing Bi-Co-S composite electrode materials.In addition,Ni andCo elements were used to combine with S elements to generate binary metal sulphides to reduce the amount of cobalt elements used and to enhance the electrochemical performance of the electrode materials through rich redox reactions.The research in this paper and the results obtained are as follows.（1）A simple one-step hydrothermal method was used to combine the BiCo-12electrode material,which has a relatively high specific capacitance(753.5 F·g^-1 at 0.5A·g^-1)and maintains an initial specific capacitance of about 80%after 3000 cycles.The asymmetric supercapacitor device assembled from BiCo-12 and AC electrodes has an energy density of 21.44 Wh·kg^-1 at a power density of 473.44 W·kg^-1 and 12.59Wh·kg^-1 at a high power density of 3434.10 W·kg^-1.After 3000 cycles at a current density of 3A-g-1,the initial specific capacitance of 70%is still maintained.（2）NiCo₂S₄ was successfully synthesised using the hydrothermal method,and this electrode material can be used to obtain a relatively high specific capacitance(770 F·g^-1at 1 A·g^-1)in KOH electrolyte solution of 3 mol·L^-1.The specific capacitance value of the asymmetric supercapacitor device assembled from NiCo₂S₄ and r GO electrodes changes from 81.25 F·g^-1 to 50 F·g^-1 when the current density increases from 1 A·g^-1 to8 A·g^-1.It is clear that the NiCo2S4//r GO ASC not only has a high specific capacitance,but also an excellent multiplicative performance.The energy density is 22.12 Wh·kg^-1 at a power density of 612 W·kg^-1 and still has a high value of 13.61 Wh·kg^-1 when the power density reaches 4900 W·kg^-1.After 5000 cycles at a current density of 2 A·g^-1,the initial specific capacitance of 80.8%is still maintained.