Design And Fabrication Of Novel Nickel Based Electrode Materials And Application In Supercapacitors

Supercapacitor as a new type of green electrochemical energy storage equipments possess most advantages including short charge time,high discharge efficiency,high power density,long cycle life and no pollution to the environmental friendliness.The influence of pseudocapacitance electrode materials on the energy storage performance of supercapacitors is particularly important.However,the practical development of supercapacitors is still hindered by the poor stability,weak conductivity and small specific surface area of electrode materials.In this paper,the porous nickel foam with high conductivity and large specific surface area is selected as the substrate,the novel nickel-based nano-electrode materials with large specific surface area,high conductivity and good structural stability were designed and prepared on conductive substrates by simple calcination,hydrothermal and electrodeposition methods.Electrochemical performance results show that this kind of novel nickel-based electrode exhibited excellent electrochemical performance,such as fast charging speed,high specific capacitance and long cycle life.Self-assembled asymmetrical supercapacitors can effectively widen the voltage range of devices,and thus increase their energy density.Detailed works are displayed as follows:?1?In view of the disadvantages of MnO₂ nanomaterials,such as poor electrical conductivity and poor structural stability.An effective electrodeposition strategy was used to introduce metal nickel nanotubes?NiNTAs?as conductive skeleton,and then MnO₂ and poly?3,4-ethylenedioxythiophene??PEDOT?were modified on the surface of NiNTAs to obtain PEDOT@MnO₂@NiNTAs nanocomposite electrode.The introduction of NiNTAs can not only effectively enhance the conductivity of electrode material,but also provide a large specific surface area for MnO₂ active material.The conductive polymer PEDOT has good conductivity,excellent electrochemical activity and high stability.The surface of MnO₂@NiNTAs nanomaterials modified by PEDOT can effectively improve the conductivity and structural stability of the electrode materials.PEDOT@MnO₂@NiNTAs electrode material is also applied in self-assembled asymmetric supercapacitors with an operating voltage window up to1.7 V,and exhibits a high volume specific energy density and superior cyclic stability.?2?Using self-sacrificing nickel foam to provide Ni source,a self-supporting amorphous edge coated crystalline NiS electrode material was successfully prepared by simple vulcanization calcination method.The porous nickel foam with high conductivity was used as the substrate,it provides a large specific surface area and good structural stability for the growth of NiS.The electrochemical performance test results show that the structure design of crystalline NiS coated by amorphous edges is a concept design.The obtained NiS electrode possesses high conductivity,long cycle life and excellent electrochemical activity.NiS electrode is further self-assembled into asymmetric supercapacitor,which shows excellent charge-discharge performance,high volume specific energy density,efficient energy storage capacity and good cycle stability.?3?In situ free-standing NiCo₂S₄ electrode was prepared by a simple one-step hydrothermal method using self-sacrificing nickel foam to provide Ni source,which demonstrates excellent energy storage and bifunctional electrocatalytic properties.The electrochemical performance test results showe that porous nickel foam with high conductivity was used as substrate,strong binding ability between active material and substrate material without the use of binder are the key reasons that NiCo₂S₄ electrode has high energy storage ability and superior catalytic performance of HER/OER.The NiCo₂S₄ electrode is used as a positive electrode in the self-assembled asymmetric supercapacitor,which has high volume specific energy density and excellent cycle stability.Based on NiCo₂S₄ electrode self-assembly to construct alkaline electrolytic water device,it also shows excellent performance of overall water splitting.