Controllable Preparation Of Novel Structure Carbon Spheres And Its Application In Lithium Sulfur Battery

We present a rational design and fabrication of novel three dimensional flower-like carbon spheres by hydrothermal reaction using the spinous silica spheres as template. The as-prepared carbon spheres are used as sulfur host for lithium-sulfur battery cathode. Its high specific surface area, large pore volume and the interworking mesoporous channel structure synergistically increase the sulfur loading, reduce the loss of polysulfide, facilitate the electrolyte diffusion and migration, thus improving the performance of the Li-S baterry. The effects of the host carbon material's structure on the performance of the lithium-sulfur battery were investigated in detail to reveal the structure-activity relationship. The main research contents are listed as follows:(1) The spinous silica spheres were prepared by a hydrothermal method. Exploring the key factors affecting their morphology and size of the silica spheres was to realize their controlled synthesis. A reasonable mechanism on the synthsis of the spinous silica spheres with different size was also proposed.(2) The novel flower-like carbon nanospheres were synthesized by a hydrothermal method using the spinous silica spheres and glucose as carbon source. Exploring the key factors such as the amount ratio between template and carbon source, carbonization temperature and atmosphere etc. were to regulate and control the morphology and structure of the carbon nanospheres. The effects of different structural carbon nanospheres, the amount of sulfur loading etc. on the capacity,rate capability and cycling stability of lithium-sulfur battery were investigated, being combined with the analysis of the polysulfide adsorption ability of carbon material, and the material structure and electrolyte ion before and after the cycle of the battery, to reveal the relationship between carbon material structure and performance.(3) The novel 3D nitrogen-doped flower-like carbon nanospheres were fabricated by hydrothermal method using the spinous silica spheres,and chitosan as carbon and nitrogen source. The effects of different carbonization temperature, the amount of ratio between cabon source and template etc. on the structure of carbon materials were investigated, and the effects of different structure sulfur host carbon materials on the performance of lithium sulfur cells were evaluated. In addition, we extended the application of as-prepared carbon nanospheres in the electrocatalytic oxygen reduction (ORR), and studied the effect of carbon surface area and nitrogen doping content on the ORR electrocatalytic performance.