Stabilization of Silicon Anode for Li-Ion Batteries

Micrometer-sized Si particles with nanopore structures were investigated as anode material for Li-ion batteries. The porous structure of Si helps accommodate the large volume variations that occur during the Li insertion/extraction processes. To improve the electronic integrity of the Si-based anode, a two-step process was utilized. First, chemical vapor deposition (CVD) was used to enhance the electronic conductivity of individual Si particles by depositing a uniform carbon coating on both the exterior surfaces and the pores. Next, the electronic contact among silicon particles was improved by adding Ketjenblack (KB) carbon, which exhibits an elastic, chainlike structure that maintains a stable electronic contact among silicon particles during cycling. Using this approach, an anode with a reversible capacity of more than 1600 mAh/g after 30 cycles was obtained. The combination of the nanopore structure, CVD-coated carbon on the Si surface, and the elastic carbon (KB) among the silicon particles provides a cost-effective approach to utilize the large micrometer-sized Si particles in Li-ion batteries.