Breakthrough Of High Capacitance Silicon/carbon Negative Material For Lithium Ion Power Battery

- Oct 25, 2017-

China energy storage net news: according to the ministry of science and technology website 23, currently on the market mainstream electric car mileage and People's Daily travel demand there is still a gap, promote power battery energy density is the key to solve this problem.

National key research and development plan of "new energy vehicles" key design special support to the project team of Peking University was a kind of high specific capacity since volume adaptability silicon/carbon anode materials, for the development of high power lithium ion battery, which laid a foundation to further improve the electric car mileage.

The development of high capacity negative electrode is an important precondition for the development of 400Wh/kg lithium ion battery, and the theoretical ratio of silicon base negative is 10 times that of the existing graphite negative electrode, which is the focus of the current negative electrode material development.

However, the silicon base negative electrode involves a large volume expansion in the cycle, resulting in the low circulation stability and low cyclic coulomb efficiency, which seriously restricts the practical application of high - capacity silicon base negative poles.

The project team of Peking University has prepared an egg yolk structure Si/C composite material by means of in-situ coating and etching.

Because of the buffer space between the active nano-si nucleus and the carbon shell, the composite material shows the adaptability and good structure and stability of the interface during the charging and discharging process.

The material has a capacity of 1300mAh/g, 3C, 500 weeks and 5C, with a capacity retention rate of 90% and 80% after 1000 weeks.

The work laid the groundwork for the development of a lithium ion battery with an energy density of 400 wh/kg.