Synthesis,Characterization And Energy Storage Performance Of Ni/Co/Fe-based Nanomaterials

Progressive energy conversion and storage technology has been rapidly developed,which will accelerate the application of renewable energy.In order to respond to market demands,it is urgent to develop high-performance energy storage equipment,and the electrode materials therein are the key factor affecting the performance of various energy storage devices.Nickel/cobalt/iron-based materials have received a lot of research due to their rich resources,low cost,and good electrical conductivity.However,the poor cycle stability,poor rate performance,and easy deformation and other reasons have hindered the wide applications.In this study,the construction of three-dimensional composite structure and array structure was carried out by adjusting the nickel-cobalt-iron-based nanomaterials with various morphologies to improve the overall conductivity,mechanical propertie and service life of the electrodes.The main research results are as follows:(1)The ZnCo₂S₄ nanoneedle clusters were uniformly grown on the foamed nickel by a simple hydrothermal method to form a core,and then Ni(OH)₂nanosheets were used as the shell layer.Then the ultra-thin,three-dimensional ZnCo₂S₄@Ni(OH)₂core shell structures with controllable morphology were successfully designed and prepared.The synergistic effect of the core-shell components of the micro-nano structure greatly increases the redox active sites and helps the ion transmission distance.At the same time,the flower-like morphology effectively alleviates the structural deformation during the charge storage process,thereby realizing effective regulation of electrochemical performance.As an electrode material,ZnCo₂S₄@Ni(OH)₂exhibits high specific capacitance(1193 C g^-1at 10 A g^-1)and excellent cycle rate performance(capacity retention rate is 92%after 8000 cycles).The assembled supercapacitor has a specific capacitance of 344 C g^-1at 1 A g^-1and a capacitance retention rate of 70%.Even after 5000 cycles at a scan rate of 5 A g^-1,the coulombic efficiency keeps100%,proving the excellent energy storage capacitor and electrochemical performance.In addition,the ZnCo₂S₄@Ni(OH)₂//AC device exhibits an excellent energy density of?44 Wh kg^-1at a power density of?0.83 k W kg^-1.(2)The dual-functional NiCo₂S₄polyhedral structure of supercapacitor and lithiumion battery(LIB)with excellent electrochemical performance was successfully synthesized by hydrothermal method.The polyhedral structure helps prevent the electrode material from powdering during the cycle,thereby forming a protective effect,while greatly increasing the active surface area,and further improving the electrochemical performance.The synthesized supercapacitor Ni Co₂S₄electrode has an excellent specific capacitance of 1298 F g^-1at 1 A g^-1and an excellent rate capability of?80.4%at 20 A g^-1.In addition,after 8000 cycles,the capacitance retention rate keeps 90.44%.In addition,Ni Co₂S₄as the anode in Li B provides high initial charge/discharge capacity of 807.6 and 972.8 m Ah g^-1and good rate capability at0.5C.It shows the dual-function effect of the material in the energy storage performance of supercapacitors and lithium-ion batteries.(3)Fe₃O₄/C nanospheres were synthesized by hydrothermal method and air heating as precursor,and then multiphase nanocomposite Fe₂O₃/Fe₃O₄/Fe₃PO₇@C@r GO was prepared by phosphating,sintering and composite graphene oxide.The carbonized matrix will buffer volume changes and enhance electron conduction.Therefore,a lithium-ion battery based on multiphase Fe can provide a large specific capacity of 1086 m Ah g^-1,with an initial coulombic efficiency of 87%and a current density of 0.1C.It also has excellent cycle stability and rate properties,still maintaining 87%capacity retention after 300 cycles,and maintaining a high reversibility of 632 m Ah g^-1at 10 C.The multiphase structure provides new insights for improving the electrochemical properties of TMO-based anodes in advanced alkaline ion batteries.