Density functional theory study of doped coronene and circumcoronene as anode materials in lithium-ion batteries

Density functional theory calculations are carried out to investigate the adsorption properties of Li⁺ and Li on twenty-four adsorbents obtained by replacement of C atoms of coronene (C₂₄H₁₂) and circumcoronene (C₅₄H₁₈) by Si/N/BN/AlN units. The molecular electrostatic potential (MESP) analysis show that such replacements lead to an increase of the electron-rich environments in the molecules. Li⁺ is relatively strongly adsorbed on all adsorbents. The adsorption energy of Li⁺ (E_ads-1) on all adsorbents is in the range of - 42.47 (B₁₂H₁₂N₁₂) to - 66.26 kcal/mol (m-C₂₂H₁₂BN). Our results indicate a stronger interaction between Li⁺ and the nanoflakes as the deepest MESP minimum of the nanoflakes becomes more negative. A stronger interaction between Li⁺ and the nanoflakes pushes more electron density toward Li⁺. Li is weakly adsorbed on all adsorbents when compared to Li⁺. The adsorption energy of Li (E_ads-2) on all adsorbents is in the range of - 3.07 (B₂₇H₁₈N₂₇) to - 47.79 kcal/mol (C₅₃H₁₈Si). Assuming the nanoflakes to be an anode for the lithium-ion batteries, the cell voltage (V_cell) is predicted to be relatively high (> 1.54 V) for C₂₄H₁₂, C₁₂H₁₂Si₁₂, B₁₂H₁₂N₁₂, C₂₇H₁₈Si₂₇, and B₂₇H₁₈N₂₇. The E_ads-1 data show only a small variation compared to E_ads-2, and therefore, E_ads-2 has a strong effect on the changes in V_cell.