Adsorption and diffusion of sodium on graphene with grain boundaries

Effects of grain boundaries (GBs) in graphene on adsorption and diffusion of sodium were investigated using first principle calculations. Results showed that the presence of GBs in graphene enhanced the adsorption of sodium, with their adsorption energies in the range of −1.32∼-0.79 eV, which were lower than the value of −0.67 eV for sodium adsorbed on pristine graphene. The diffusion energy barriers were in the range of 0.09-0.35 eV when sodium was diffused along GBs of graphene, whereas they were decreased when sodium was gradually diffused into the GBs. Results showed that graphene with GBs had a larger energy storage capacity for sodium than the pristine one, indicating that it can be used as a good anode material for sodium ion batteries.

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