Incorporation of silicon based materials to graphite anode has been a promising strategy to boost anode specific capacity. Due to the distinct difference between open circuit potential (OCP) of the two material, participation of silicon alloy was in later stage of delithiation under slow C-rate condition, as shown by our previous study. ¹ The present work expands silicon alloy contribution study into C-rate performance combing both experimental and Multi-Scale Multi-Dimensional modeling² efforts. Diffusion overpotential drastically increases at high C-rates as diffusion coefficient of silicon alloy is smaller by one to two orders of magnitude than that of graphite¹. We are able to track evolution of Si alloy exchange current density along charging and discharging process, and quantify contribution of silicon alloy in different C-rates. A critical C-rate level is also suggested, depending on blending ratio with graphite, beyond which enhancement of silicon alloy is diminished.

1. Cao, L.; Yang, C.; Santhanagopalan, S.; Inman, K.; Pesaran, A., Evaluation of Silicon Alloy Contribution in Blended Lithium-Ion Battery Anode with Graphite. Meeting Abstracts 2017, MA2017-01 (1), 27.
2. Kim, G.-H.; Smith, K.; Lawrence-Simon, J.; Yang, C., Efficient and Extensible Quasi-Explicit Modular Nonlinear Multiscale Battery Model: GH-MSMD. Journal of The Electrochemical Society 2017, 164 (6), A1076-A1088.