Chunmei Ban1

1, National Renewable Energy Laboratory, Lakewood, Colorado, United States

The demands of sustainable high-energy-density rechargeable batteries have led to the exploration of high-capacity and low-cost electrode materials. Based on reversible alloying-dealloying reactions, silicon stores 10 times more lithium (Li22Si5, 4,200 mAh g-1; Li15Si4, 3,579 mAh g-1, 8,343 Ah L-1) than the current commercial graphite anode (LiC6, 372 mAh g-1, 804 Ah/L). However, unlike the topotactic intercalation of Li into carbonaceous materials, the alloying/dealloying reaction causes much more dramatic, three-dimensional chemical and structural rearrangements on the surface and bulk structure, and results in a fast degradation in cycling performance. Moreover, the formation of solid electrolyte interphases on the Si surface results in the loss of lithium inventory and low Coulombic efficiency. Besides of using sophisticated design of nanostructure silicon materials and electrodes, our research has concentrated on surface modification strategies to stabilize the surface of the reactive silicon materials, but also accommodate the volumetric changes during lithaition/delithiation of silicon materials. The effects of the surface modification have been investigated through morphology, structure, mechanical and electrochemical characterization and analysis methods. The research has elucidated the important role of surface modification in stabilizing the cycling performance and enable a high level of material utilization at high mass loading. This talk will focus on reviewing the surface modification approaches used for improving electrochemical performance, and elaborate the effects of surface modification on the surface chemistry and electrochemistry of silicon-based anodes, and also discuss the strategies towards developing practical silicon-based anodes for high-energy-density lithium-ion batteries.