Can P- and Oxidized P-doped Graphene be a Good Anode for Na-Ion Batteries?: A First-Principles Assessment

Sodium ion batteries (NIBs) become an important emerging alternative to lithium ion batteries (LIBs) because of low cost and suitability for large-scale applications. However, optimizing anodes in NIBs is still a challenge. In this paper, we investigated the possibility of using P- and oxidized P-doped graphene as an anode in NIBs. We reveal important fundamental properties of sodium adsorption on P- and oxidized P-doped graphene by employing first principles calculations. Our results suggest that Na adsorption on the single side of substrate followed by on the other side is the preferred configuration with high Na capacity of 511 mAh g −1 . Na is predicted to migrate with a low diffusion barrier near the protrudent P and OP on the substrate. Although Na has to cross an elevated diffusion barrier to escape from the most stable site interacting with the P and OP, this can be significantly mitigated by increasing the adsorbed Na concentration. Our calculations also demonstrate the structures mostly maintain the metallic properties thus shows high electron mobility upon a wide range of sodiation level. Our findings indicate that P- and oxidized P-doping of graphene anodes can be a promising route toward increasing the overall performance of NIBs for practical application.