Adsorption and diffusion of lithium and sodium on the silicon nanowire with substrate for energy storage application: A first principles study

The adsorption and diffusion properties of Li/Na on the Si nanowire (NW) with substrate are analyzed by the density functional theory (DFT) calculations. The Li/Na prefers to adsorb on the corner of the Si NW with substrate and the adsorption energies on different sites vary from -1.32 eV to -0.74 eV. The diffusion pathways and corresponding energy barriers of lithium/sodium on the Si substrate and sidewall of the Si NW are calculated by the nudged elastic band (NEB) method. Moreover, when Li/Na moves around the Si NW, the Si NW would bend with the maximum displacement of similar to 0.76 angstrom. Finally, the energy barriers are 0.61-0.81 eV when Li/Na diffuses across the Si NW, indicating the Si NW may be applied as anodes in both lithium and sodium ion batteries. This work would help to investigate the Li/Na adsorption and diffusion properties on various nanowires with substrates and provide guidelines for the design of Si anodes in sodium ion batteries.