Preparation Of Electrode Materials For Nickel Selenides And Their Applications In Supercapacitors

In the past several years,many flexibility,lightweight,wearable electronic product which revealed novel designs have been developed rapidly.In order to achieve these devices,a lightweight and wearable energy storage device is essential.Research on flexible supercapacitor has been developed.But how to increase the energy density is always a barrier to supercapacitors.Increasing the capacitance and potential is an effective way to improve the energy density of supercapacitors.According to the above viewpoints,the work of this paper is as follow:?1?A flexible carbon cloth material with three-dimensional structure was used as a collecting fluid,and NiSe₂ electrode materials were prepared by simple continuous ion layer adsorption method at normal temperature.After electrochemical testing,the flexible NiSe₂ electrode showed good electrochemical performance,and the specific capacitance was 971.6 F g^-1(the current density is 1 A g^-1).The NiSe₂ and AC electrodes were assembled into flexible asymmetric capacitors and the potential window was extended to 1.6 V.Under the two-electrode system,the specific capacitance of NiSe₂//AC asymmetric capacitors is 68 F g^-1,and the energy density is25.7 Wh kg^-1.After the electrochemical cyclic stability test of 2000 times,it still maintained a retention of 81.7%,which showed good circulation stability.?2?In this chapter,a NiSe₂ nanosheet with high specific capacitance was synthesized on the flexible carbon cloth by using simple and efficient electrodeposition method at room temperature.Testing NiSe₂ electrode materials in current density from2 to10 A g^-1,specific capacitance change to 996.3 from 1058.5 g F^-1,it can explain the NiSe₂ electrode has high specific capacitance and the retention of performance.The NiSe₂ electrode and AC electrode were assembled into a NiSe₂//AC asymmetric capacitor for electrochemical testing.When the power density is 800 W kg^-1,the energy density reaches 32.7 Wh kg^-1.After the electrochemical cyclic stability test of 2000times,it still maintained a retention of 86 percent,which showed good cycle stability and durability.?3?In this chapter,3d Ni0.85Se nanosheet material was prepared by hydrothermal method.Ni0.85Se was coated on carbon cloth to make up the flexible electrode.By electrochemical test,687 F g^-1(2497 mF cm^-2)was obtained.With Ni_0.85Se and AC as positive and negative electrodes,the Ni0.85Se//AC flexible asymmetric supercapacitor was constructed.The electrochemical results show that the capacitance of the capacitor is 96.3 F g^-1 under the current density of 1 A g^-1.The maximum energy density and power density were 34.2 Wh kg^-1 and 4000 W kg^-1 respectively.Under the current density of 2 A g^-1,the electrochemical cyclic stability test was carried 5000 times.The capacitance retention rate is still up to 94%,and the stability is excellent.