Research on the Application of Silicon Nanowires-based Anode Materials for Lithium Ion Batteries

The project aims at the development of silicon (Si) nanowire/graphite composites and their industrial application as anode materials for high-performance lithium ion batteries (LIBs). In comparison with the commercial graphitic carbon material, Si is featured with a theoretical capacity 10 times higher than that of graphite and better safety. However, the practical application of Si has been hindered by the quick capacity decay associated with its low electrical conductivity, massive volume change during the charging and discharging processes, and poor compatibility with conventional electrolyte. In this project, we will cooperate with Shenzhen BTR New Energy Materials Inc. (the largest manufacturer of LIB anode materials, and supplier for Samsung and BYD, etc.), propose to grow directly Si nanowires on highly-conductive porous graphite substrates, and encapsulate the Si nanowires with a thin layer of carbon coating by using the low-cost vapor deposition techniques. Through controlling the factors such as the crystallinity, orientation, aspect ratio and density of Si nanowires, the thickness and structure of carbon encapsulation layer, and the silicon/carbon ratio, the volume expansion effect of Si will be suppressed, and the capacity and cycling performance of Si-based electrodes will be effectively improved to meet the requirement for fabricating new Si-based LIBs. The composite materials are expected to deliver a reversible specific capacity of 1200 mAh/g (about 3 times higher than that of commercial graphite anode), initial charge-discharge efficiency no less than 90%, and capacity retention no less than 92% after 100 cycles. The cost will be no more than 100 USD/kg. The completion of this project will provide technical guideline for the industrial production of Si-based anode materials, which may promote the advance of LIB technology and benefit the development of electric vehicle industry.