Study Of Cathode Materials Of Lithium-sulfur Batteries Based On Porous Conductive Matrix

Facing the rapid growing consumption of limited fossil fuels and global environmental problems, the development of high-energy, high-power density and high-safety batteries is in great demand. In order to reduce the proportion of fossil energy in economic development, implementation of the "green energy", the government of our country has issued a series of policies and measures to encourage the development of clean energy. However, the solar, wind, biomass, geothermal and other familiar clean energy is easily affected by the natural factors, and is difficult to meet the continuous and stable energy supply requirements. So, we need to seek a kind of media device for energy conversion and storage, to achieve a stable energy supply to the outside. Power and energy storage battery can achieve this function well, realize the space-free and time-free of energy. However, the power and storage battery available in the market, such as Lead-acid, Ni-H, Ni-Cd, Lithium-ion battery, is difficult to satisfy the requirements. Therefore, we need to develop a better performance power and energy storage battery with higher energy density. The theoretical energy density of lithium sulfur battery reaches as high as 2600Wh/kg, is one of the ideal candidates of next generation power and energy storage battery. In addition, the active substance, elemental sulfur, is environmentally friendly, inexpensive.However, the problem such as, the "shuttle" effect, the insulation of elemental sulfur, the volume expansion, makes the lithium sulfur battery is difficult to achieve commercial application. The low conductivity of sulfur, and the complex electrochemical reaction of the cathode, determines the cathode material is the key research points in the lithium sulfur battery.Detailed contents are listed as follows:1. The porous carbon was obtained by carbonize the corn grain, and then sulfur/ porous carbon composite was successfully prepared by solvothermal method. The sulfur/porous carbon composite was then used as cathode of lithium sulfur battery, and its electrochemical performance was tested. The results show that, after 50 charge and discharge cycles at 0.2C rate, the specific capacity was 293 mAh/g.2. For the first time, the metal was used as the carrier material of cathode active material in the lithium sulfur battery research field. The nanoporous gold (NPG) with the aperture of 5～20 nm was designed and prepared, and was then annealed with the sulfur. Being assembled into a battery, a specific capacity of 610 mAh/g was obtained after 1000 cycles as the S/NPG was tested at 1 C rate, exhibited an excellent cycling performance. Even being tested at a rate as high as 10 C, a specific capacity of 360 mAh/g could be obtained after 500 cycles.