Journal
ACS APPLIED MATERIALS & INTERFACES
Volume 13, Issue 18, Pages 21362-21370Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acsami.1c03366
Keywords
lithium-ion battery; Si/C composite anode; first-principles calculation; Li diffusion behavior; mechanism
Funding
- University of North Carolina at Charlotte
- U.S. Department of Energy's (DOE) Office of Energy Efficiency and Renewable Energy (EERE) Vehicle Technologies Office
- U.S. Department of Energy Office of Science Laboratory [DE-AC0206CH11357]
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This study investigates the atomic behavior of Li diffusion in Si/C composite materials using density functional theory, comparing two structural mixing formats: simple mixture and core-shell. It is found that carbon material increases Li diffusion in silicon by about 50%, with the mixture mode showing a more significant boost. The results offer new insights into Li diffusion behavior in Si/C composites and provide guidance for battery modeling and structure design.
Recently, Si/C composite materials have attracted enormous research interest as the most promising candidates for the anodes of next-generation lithium-ion batteries, owing to their high energy density and mechanical buffering property. However, the fundamental mechanism of Li diffusion behavior in various Si/C composite materials remains unclear, with our understanding limited by experimental techniques and continuum modeling methodologies. Herein, the atomic behavior of Li diffusion in the Si/C composite material is studied within the framework of density functional theory. Two representative structural mixing formats, that is, simple mixture mode and core-shell mode, are modeled and compared. We discover that the carbon material increases Li diffusion in silicon from 7.75 x 10(-5) to 2.097 x 10(-4) cm(2)/s. The boost is about 50% more obvious in the mixture mode, while the core-shell structure shows more dependence on the atomic structures of the carbon layer. These results offer new insights into Li diffusion behavior in Si/C composites and unlock the enhancing mechanism for Li diffusion in Si/C. This understanding facilitates the modeling of batteries with composite anodes and will guide the corresponding structure designs for robust and high-energy-density batteries.
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