AlN nanotubes and nanosheets as anode material for K-ion batteries: DFT studies

•Application of AlN nanostructures in K-ion batteries is studied.•For (5,0) AlN tube, maximum energy barrier for K+ migration is 8.3 kcal/mol.•Ion diffusion coefficient is 8.58 × 10−8 cm2/s.•The cell voltage increases by decreasing the AlN curvature.•The AlN nanosheet is the best anode for k-ion batteries, compared to nanotubes. We explored the possible application of (5,0), (6,0), (7,0), (8,0) and (9,0) zigzag AlN nanotubes and an AlN nanosheet in the K-ion batteries (KIBs) using B3LYP-gCP-D3/6-31G* model chemistry. In the case of (5,0) tube, the K and K+ adsorption energies, maximum energy barrier for K+ migration, ion diffusion coefficient, and cell voltage are calculated to be −1.22 and −0.32 eV, 0.36 eV, 8.58×10−8 cm2/s, and 0.90 V, respectively. We found that dispersion term (D3) has much more significant effect on the K/K+ adsorption energies compared to the basis set superposition error (gCP). Reducing the AlN nanostructure curvature, the K atom interaction significantly weakens while the K+ interaction is slightly affected. As a result, the cell voltage increases by decreasing the AlN curvature, and reached to 1.11 V in the AlN sheet. The AlN nanostructures with lower curvature may be plausible candidates for application in the anode of KIBs.