October 23 from the Ministry of Science and Technology was informed that the national key research and development program "new energy vehicles" focus on special support of the Peking University project team designed to prepare a high specific volume of self-volume adaptive silicon / carbon anode material for the development of high specific energy Lithium-ion battery, to further improve the electric vehicle mileage has laid the foundation.

The development of high-capacity negative electrode is an important prerequisite for the development of 400Wh / kg lithium-ion battery. The silicon-based negative electrode has 10 times the theoretical specific capacity of the existing graphite anode, which is the focus of the development of the current anode material. However, the silicon-based negative electrode involves a huge volume expansion during the cycle, resulting in poor cycle stability and low cycle Coulomb efficiency, which seriously restricts the practical application of high-capacity silicon-based negative electrode. Peking University project team through in situ coating, etching and other ways to prepare an egg yolk structure Si / C composite materials. Due to the reserve space between the active Si and the carbon shell, the composite material exhibits self-volumetric adaptability and good structure and interfacial stability during charge and discharge. The material has a specific capacity of 1300mAh / g, 3C, 500 weeks and 5C, 1000 weeks after the capacity retention rate of up to 90% and 80%. This work laid the foundation for the development of lithium-ion batteries with an energy density of 400 Wh / kg.