Preparation Of Ni-Co PBA-derived Carbon Nanotube Composites And Study On Supercapacitor Properties

Supercapacitors have attracted attention in the field of energy storage due to their advantages of long cycle life,high charge-discharge efficiency,and low temperature limit.However,the insufficient energy density limits application of supercapacitors.The development of functional electrode materials with high specific capacity,structural stability,and energy density is an effective measure for further practical applications of supercapacitors.MOFs have attracted extensive research interests due to their large specific surface area and easily controllable chemical structure.Carbon nanotubes with high aspect ratio derived from MOFs can not only alleviate their own agglomeration,but also well inherit advantages of MOFs.As a subclass of MOFs,Ni-Co PBAs have been extensively studied due to their tunable composition,controllable structure,excellent electrochemical performance and high stability.Based on the synergistic effect of multiple components,in this paper,Ni-Co PBA nanocubes are used as sacrificial templates to derive high-performance carbon nanotube composites through heat treatment and selenization processes.(1)Nitrogen-doped encapsulated metal selenide carbon nanotube composites(NCNTs/NiCo-Se)are successfully synthesized using Ni-Co PBA nanocubes as precursors by CVD method and selenization process.The influence of nitrogen and propylene flow rates on the morphology and structure of NCNTs/NiCo is studied,and the growth process and mechanism of the conversion of Ni-Co PBA into carbon nanotubes are elucidated.The composite material exhibits excellent performance benefiting from the special structure of carbon nanotube-encapsulated nickel-cobalt selenide and multi-component synergy.(2)Bamboo-structured carbon nanotubes encapsulated with nickel-cobalt metal particles(V-NCNTs/NiCo-Se)are derived from Ni-Co PBA by CVD in a vertical tube furnace.Contact of the precursor active surface with the carbon source enhances the yield of Ni-Co PBA-derived carbon nanotubes based on the fluidity of the atmosphere in the cavity of a vertical tube furnace.The influence of N₂ and C₃H₆flow rate on the morphology,structure and yield of carbon nanotubes is investigated.The electrochemical properties of electrode materials with different structures are investigated.Compared with the carbon nanotube composites prepared by the horizontal tube furnace,the specific capacity of V-NCNTs/NiCo-Se-1.2/0.3 is increased by 13.3%.The assembled device exhibits high energy density and long-cycle stability.(3)The self-supporting N-doped carbon nanotube selenide composite(NF@NCNTs/NiCo-Se)is derived from the Ni-Co PBA precursor supported by NF via CVD process and selenization process.NF@NCNTs/NiCo-Se avoids the use of binder and reduces the internal resistance during the electrochemical process,which further improves the electrochemical performance.After combining with hydroxide via a hydrothermal strategy,the prepared NF@NCNTs/NiCo-Se/Ni(OH)₂ electrode exhibites excellent specific capacity.