Preparation Of Ni/CNT And Carbon-based Materials And Their Application In Lithium-sulfur Batteries

With the rapid development of society,lithium-sulfur batteries with extremely high theoretical capacity(1650 m Ah g^-1)and energy density(2600 W h kg^-1)have aroused great interests and attention to satisfy the increasing demand for portable devices and electric vehicles.However,some problems severely damage the commercial application of Lithium-sulfur batteries:the electronic insulation of sulfur and its discharge products?Li₂S,Li₂S₂?,the huge volume changes during charge and discharge,shuttle effect of polysulfides,the pollution and corrosion of lithium anodes.Thus,it still has practical significance to research high-performance lithium-sulfur cathode materials.To solve the problems faced by lithium-sulfur batteries,designing and synthesizing sulfur hosts which could effectively fix polysulfides is an effective way to improve the performance of lithium-sulfur batteries.Therefore,this paper is based on carbon material and synthesized high-performance lithium-sulfur cathode materials through designing and optimizing the structur and introducing metal components which has a catalytic effect on polysulfides.The specific research contents of this paper are as follows:?1?Through microwave-assisted reduction,nickel nanoparticles were successfully supported on the surface of nitrogen-doped carbon nanotubes?N i/CNT-N?.The physical characterization methods such as transmission electron microscopy and X-ray diffraction confirmed that nickel oxide components exist on the surface of nickel nanoparticles.N itrogen doping and intrinsic defects were beneficial to the nucleation and loading of nickel on the surface of carbon nanotubes.After electrochemical performance tests,it was found that nickel nanoparticles synergistically promoted the reduction reaction kinetics of polysulfides,suppress the"shuttle effect"and improve the performance of lithium-sulfur batteries.At the current density of 0.1 C,the first discharge capacity of N i/CN T-N/S electrode is 905 m Ah g^-1and it still has a reversible capacity of 593 m Ah g^-1 after 100 cycles.?2?Two-dimensional thin film nitrogen-doped ordered mesoporous carbon?NOMC-2D?and three-dimensional nitrogen-doped ordered mesoporous carbon?NOMC-3D?were synthesized by using different morphologies of mesoporous silica as templates,1,10-phenanthroline monohydrate as carbon and nitrogen source s.Compared with NOMC-3D,NOMC-2D has more pyridine-N and graphite-N content,which can provide more sites for polysulfide adsorption.NOMC-2D/S electrode has smaller polarization at a current density of0.1 C,higher discharge specific capacity(980 m Ah g^-1)and excellent rate capability.