Unlocking Multiphysics Design Guidelines on Si/C Composite Nanostructures for Next Generation High-Energy-Density and Robust Lithium-Ion Battery Anode

Abstract

Lithium ion batteries (LIBs) have been one of the most popular energy storage devices in many fields. Along with the development of the LIBs, high energy density becomes one of the most urgent requests in the market. To achieve this goal, high capacity anode materials are attracting more and more research interests, among which the Si related material is one of the most promising candidates for next generation LIBs. The biggest problem of Si related materials is the tremendous volume change during the cycling. Thus, many strategies have been proposed to solve this problem, e.g. nano engineering, composites, etc. The Si/C composite material, is widely adopted because it has the advantage of nanomaterials as well as compensates the weakness of nano-properties. Current material fabrication guidance for novel designs of Si/C composite particle materials for anode only focuses on electrochemical behavior and redox reactions at the nano/micro level; however, they cannot provide detailed information for predicting mechanical deformations of the composite particles especially coupled with electrochemical and thermal fields. Herein, an electro-chemo-mechanical model is established and implemented to quantitatively analyze the multiphysics behavior of five representative Si/C composite nanostructures. Numerical simulation manifests that yolk-shell and dual-shell structures are more robust in terms of particle fractures. With the consideration of electrochemical performance, the yolk-shell structure is the most excellent type among the compared five Si/C composites. Finally, design guidance is mapped to further illustrate quantitative structure-property relations. This study provides novel insights on Si/C composite nanostructure anode material design and further powerful design tools for next-generation high-energy-density lithium-ion batteries.