The Preparation Of Titanium Nitride Integrated Sulfur Host And The Research Of Energy Storage Performance In Lithium-Sulfur Batteries

High sulfur loading and high sulfur utilization are the great challenges to improve the energy density and commercialization of lithium-sulfur battery（LSBs）.The development of three-dimensional current collector with integrated and self-supporting structure is an effective strategy to realize efficient conversion of polysulfides under high surful loading.In the early stages,a large number of integrated electrodes based on carbon-based materials were reported,but the lack of chemisorption capacity and catalytic activity of carbon-based materials and the difficulty of electrolyte infiltration due to the large specific surface area restricted the development of LSBs.Therefore,using transition metal nitride-titanium nitride（Ti N）with high conductivity,strong chemisorption and high catalytic activity as matrix material,two kinds of non-carbon sulfur-limiting carriers with integrated and self-supporting structures were designed and prepared:Ti N porous ceramic integrated sulfur-limiting carrier and Ti N self-supporting thin film integrated sulfur-limiting carrier,and they were successfully applied to LSBs.To achieve excellent electrochemical performance under high conductivity and high sulfur loading.The specific research contents are as follows aspects:（1）Ti N porous ceramics were sintered at high temperature,and the pores in the ceramic matrix could be adjusted by adjusting the powder composition,pore-forming agent content and sintering temperature.Integrated titanium nitride/sulfur composite cathode was prepared by loading active material sulfur into porous titanium nitride ceramics with good porosity and large specific surface area by melting method.The utilization rate of sulfur can be effectively improved by making use of the intrinsic characteristics of titanium nitride with high conductivity and high catalytic activity.Therefore,the quasi-solid reaction can be realized through pore adjustment and the amount of electrolyte can be greatly reduced,and the sulfur loading can be effectively increased.The integrated structure avoids the use of conductive agent and binder,effectively reduces the interface contact resistance of the electrode,provides a simple,efficient and feasible strategy for the commercial application of lithium-sulfur battery,and can be used for reference for the research of other batteries,such as all-solid-state batteries.In terms of electrochemical performance,when the sulfur load is 1.0mg cm^-2,the discharge capacity of the Ti N@S positive electrode can reach 1250.6 m Ah g^-1 in the first circle,and the reversible capacity can still reach 635.8 m Ah g^-1 after 200 cycles at 0.5 C current density.（2）Titanium nitride nanobelts（Ti N-NB）thin films have flexible,conductive,layered porous and independent structures.As carbon-free sulfur carriers,sulfur electrodes with high sulfur loading and high energy density have been successfully constructed.In addition,the intertwined three-dimensional nanoribbon network macroscopically can provide an effective transport path for lithium ions and electrons,and the high specific surface area and porosity provide a necessary guarantee for the adsorption and catalytic transformation of polysulfides.