Silicon based anodes with much improved capacity retention and rate capability have been demonstrated through structural/morphological modifications and alloying with active/inactive elements. With the unique benefits of these innovative approaches, comes the challenges to investigate the lithiation behavior with increasing levels of complexity associated with the surface, interface, and alloying effects. We will present some results of our recent first principles study on the structural evolution, energetics and Li diffusion property in Si-transition metal (Si-M) alloys and Si-graphene composites. As the lithiation behavior is extremely sensitive to the alloy composition and local atomic environment, our calculations attempt to address the relation between the tunable material properties and anode performance. More specifically, we look into the variations in Li incorporation, distribution and the impacts on Li mobility when the alloying elements or surfaces/interfaces are present.
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