Lithium-ion batteries have been widely used in portable electronic devices, electric vehicles and energy storage areas, but subject to positive and negative active material specific capacity, the current commercial lithium-ion battery only for low power demand. Silicon is thought to be the next-generation cathode material for large-capacity lithium-ion batteries with a theoretical specific capacity of 4200 mAh / g, more than ten times that of the conventional graphite anode (340 mAh / g). However, the volume of the silicon negative electrode changes more than 300% during the charging and discharging process, resulting in the deactivation of the active material from the collector, and the generation of the SEI of the solid electrolyte interface, which makes the efficiency of the Coulomb negative. The use of all batteries.
Xi'an Jiaotong University developed a high Coulomb efficiency of silicon anode lithium battery
Recently, Professor Zheng Xiaoquan, State Key Laboratory of Electrical Equipment and Electrical Insulation, Xi'an Jiaotong University School of Electric Power, worked with Prof. Cui Yi from Stanford University and Prof. Li Ju from the Department of Nuclear Engineering of MIT to work out a high- Density (Si) / TiO 2 / Si (subscript x) / TiO 2 / Si (subscript x) / TiO 2 / TiO 2 / Si 3 O 3 / TiO 2 composite was prepared and compared with the conventional graphite negative electrode at a volume capacity of 1100 mAh / cm3 and 762 mAh / g. A special method was used to coat the outer surface of the nanometer silicon negative electrode with a layer of artificial titanium dioxide nanometer layer to synthesize the Si @ TiO2 yolk-shell structure negative electrode of high mechanical strength. In situ TEM testing showed that the mechanical strength of the titanium dioxide shell is five times that of amorphous carbon. The experimental results show that the Si @ TiO 2 electrode sheet can withstand the high strength of the roller to increase the density of the electrode sheet, and the self-repairing of SEI makes the outer surface of Si a dense artificial SEI + SEI, Of the Coulomb efficiency of 99.9% or more, to meet the application of industrial standards, will effectively promote the silicon anode in the battery industry in the commercial application.
The study was published in the paper on January 6, 2017 in the British Royal Society of energy class journals Energy & Environmental Science (impact factor 25.427), the paper entitled "Self-healing SEI enables full-cell cycling of a silicon Which is the first author of the paper, Xi'an Jiaotong University State Key Laboratory of electrical insulation for the paper the first unit. The main researchers involved in this project were Dr. Li of Tongji University School of Materials and Dr. Akihiro Kushima of the Department of Nuclear Engineering at MIT.