TU-TESL

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According to foreign media reports, a research team at the University of Manchester in the UK has developed a graphene doped cathode to achieve a highly stable lithium sulfur. In the paper, the researchers said that the lithium sulfur battery made of the cathode material can withstand 500 charge and discharge cycles when charging at 0.5c, 1C, 2C and 3C. (image source: University of Manchester) the cathode combines a laser synthesized sulfur (S) and nitrogen (N) doped graphene electrode (no binder) with nanoparticles containing molybdenum sulfide (MoS2). The porous graphene structure doped with nitrogen and sulfur enhances the adsorption capacity of the interface by producing sulfur dioxide, while sulfur dioxide can inhibit the diffusion of polysulfide to the electrolyte by promoting the chemical combination of oxygen-containing functional groups and sulfur. Low electrolyte resistance, low interphase contact resistance and low charge transfer resistance accelerate electron and lithium ion transport in graphene doped with laser-induced nitrogen and sulfur. Theoretically, the specific capacity of lithium sulfur battery is very high, up to 1675 MAH / g, and the energy density is also high, up to 2600 WH / kg, which is a potential choice for future batteries. Although the energy density of the actual lithium sulfur battery is only 550 to 660 WH / kg, which is 20% of the theoretical energy density, this level of energy density has been realized in the lithium sulfur battery made of LiCoO2 cathode. Therefore, to achieve a higher level of capacity and energy density is one of the main challenges faced by lithium sulfur batteries, and the low cycle stability also hinders the practical application of lithium sulfur batteries. Soluble lithium polysulfide is the key factor of "shuttle" effect in sulfur cathode electrochemical reaction, which will lead to low cycle stability of lithium sulfur battery. Therefore, the scientists used a pulse UV (ultraviolet laser) direct writing technology to form graphene electrodes with sulfur and nitrogen doping containing multiple nanoparticles (such as silver, platinum, silicon and molybdenum sulfide), wherein molybdenum sulfide is made of an organic ink with a special formula and a variety of micro particles. The process is a one-step molding process, which does not need binder to form cathode collector of lithium sulfur battery. The process can make the lithium sulfur battery endure long-term charge discharge cycle, and hardly reduce its power storage.