Preparation And Electrochemical Properties Of CdSe Based Electrode Materials

As an ideal green energy device,supercapacitors have the advantages of high security,high power density,fast charging and discharging speed,but their application still has some limitations due to the low energy density.In order to solve this problem,CdSe electrode materials with stable structure and high theoretical specific capacity are selected for research.The electrochemical performance of CdSe and transition mono-metal sulfide Co S and transition binary metal sulfide Ni Co S nanocomposite electrodes is analyzed,and these electrodes are assembled into aqueous and solid-state symmetric supercapacitors,respectively.Three main aspects of the work are as follows:（1）In situ growth of condensed spherical CdSe materials on nickel foam by electrodeposition.The electrochemical performance of CdSe with deposition time of20 min,30 min,40 min and 50 min was studied.The test results indicate that the electrochemical performance of CdSe-40 electrode obtain after deposition time of 40min is the best,which exhibit a high specific capacitance of 1542 m F/cm² and the capacitance retention of 78.9%.The energy density of the aqueous capacitor is 17.5μWh/cm² and the solid state capacitor is able to reach 14.8μWh/cm².（2）Co S@CdSe nanocomposites were prepared by a two-step electrodeposition method using CdSe deposited directly on nickel foam for 40 min as the substrate,Co Cl₂·6H₂O as the cobalt source and CH₄N₂S as the sulphur source.The nanocomposite electrodes with the best electrochemical performance were selected among the Co S@CdSe electrodes with deposition times of 900 s,1200 s,1500 s,1800 s and 2100 s.The electrodes were used as positive and negative electrodes to assemble symmetrical supercapacitors and to investigate the practical application capability of the capacitor devices.The results show that the Co S-1500@CdSe nanocomposite electrode obtain at a deposition time of 1500 s has the best electrochemical performance,with the specific capacitance can reach 760 m F/cm² and the capacitance retention is 91.7%.The maximum energy density of the aqueous capacitor is 75.6μWh/cm² and the solid-state capacitor is 35.5μWh/cm².（3）Ni Co S@CdSe nanocomposite electrode materials were prepared using a two-step electrodeposition method with CdSe-40 as the substrate,CH₄N₂S as the sulfur source,Co Cl₂·6H₂O as the cobalt source and Ni Cl₂·6H₂O as the nickel source.The results manifest that the electrochemical performance of the Ni Co S-40@CdSe composite electrode obtain by depositing 40 min of Ni Co S is optimal,and the specific capacitance can reach 1204.17 m F/cm².The Ni Co S-40@CdSe nanocomposite electrode is used to assemble a symmetric supercapacitor and to apply the capacitor device.The maximum energy density is 117.78μWh/cm² for aqueous capacitors and139.88μWh/cm² for solid state capacitors.