Study On Titanium Oxide Anode Material And Its Modification For Na-ion Battery

Sodium ion battery system is considered as an ideal choice for large-scale energy storage due to its abundant resources and high safety.Anode and anode materials as the key components of sodium ion battery directly determine the electrochemical performance of the battery,so the design and preparation of high-performance electrode materials is the critical factor in the construction of sodium ion battery system.Among the anode materials for sodium ion batteries,titanium oxide electrode materials have attracted extensive attention because of the characteristics of suitable working voltage,small strain expansion,excellent rate performance,environmental friendly,safety and low cost.In this paper,adjusting the morphology of titanium oxide,forming carbon composite materials and doping with heteratomic elements are used to improve the electrochemical properties of the materials.1.Co Ti O₃/C porous hybrid anode material was prepared by simple solvation method.Co Ti O₃/C shows an excellent electrochemical performance in sodium ion battery.Co Ti O₃ nanoparticles possess uniform one-dimensional hexagonal prism morphology,stable microstructure,and interconnected electron transport channel.In addition,the special structure of Co Ti O₃ embedded in amorphous carbon can inhibit the collapse and agglomeration of the material structure.Co Ti O₃/C composites exhibit excellent rate of 256.2,221.5,184.0,147.1,109.0 and 86.1 m Ah g^-1 at 50,100,200,500,1000 and 2000 m A g^-1,respectively.2.Firstly,Ni doped nanoparticles were synthesized by simple hydrothermal method.Then,using cheap thiourea as both nitrogen source and sulfur source,polyatomic doped N,S-NTC was synthesized.N,S-NTC exhibits a high discharge capacity of 310.1 m Ah g^-1 at the current density of 0.1A g^-1,and the initial coulomb efficiency reaches 51.8%.In addition,N,S-NTC can provide a high capacity of about 185.5 m Ah g^-1 at a large current density of 1 A g^-1.N,S-NTC exhibits good cyclic stability,and the polyatomic doping is due to the synergistic advantage of the enhancement of intrinsic electronic conductivity and ionic conductivity due to the more oxygen vacancy and the narrower bandgap.3.Organic precursors of polymetallic complexation were synthesized by simple solvation reaction.Co_xNi_1-xTi O₃/C series composites of oxide and carbon were prepared by calcination in argon,and the effect of the ratio of Co and Ni on the morphology of the composites was studied.The obvious polyporous structure can be observed on the surface of the particles.The rough surface and the interconnected nanoparticles effectively inhibit the volume change during the redox reaction process.Overall,Co_0.5Ni_0.5Ti O₃/C composite showed best electrochemical properties.Co_0.5Ni_0.5Ti O₃/C provides 221.6,182.5,132.6,105.0,85.5,59.7m Ah g^-1 discharge capacities at the current densities of 0.1,0.2,0.5,1,2,5A g^-1,respectively.