A quantum mechanical study on the application of inorganic BC2N nanotubes in the Na-ion batteries

摘要

We scrutinized the potential application of a BC2N nanotube as an anode material for the Na-ion batteries (NIBs) using B3LYP-gCP-D3/6-31G* model chemistry. Two kinds of hexagonal rings (B2C2N2 (alpha) and BC4N (beta)) are identified, being nonaromatic based on the NMR calculations. The Na cation adsorbs on the alpha and beta rings with adsorption energies of -46.7 and -38.1 kcal/mol via different mechanisms, namely, cation-lone-pair and cation-pi interactions, respectively. The predicted adsorption energy for Na atom is -12.0 kcal/mol, including a large dispersion term of -5.7 kcal/mol. The BC2N nanotube preserves its initial structure during the Na/Na+ adsorption because of a small calculated deformation energy. The maximum energy barrier for an Na cation migration on the tube surface is 13.7 kcal/mol which yields a diffusion coefficient of 3.70 x 10(-10) cm(2)/s. Thus, the BC2N nanotube provides a great ion mobility leading to a faster charge/discharge rate. The predicted cell voltage for BC2N nanotube is 1.58 V, being larger than that of different BN and AlN nanostructures and graphene. All of above offer the BC2N nanotube as a plausible anode material for application in the NIBs.