A comparative analysis of X-encapsulated (X= F−, Cl−, Br−) and doped B38 (Al or N atom) nanocages for lithium-ion Batteries

Abstract

The study investigates the structural and electronic properties of the B₃₈ nanocage, focusing on its interaction with Li and Li⁺ ions for Li-ion batteries. The doping B₃₈ with aluminum (Al) or nitrogen (N), and the encapsulation of halides ($F^{-}$, ${\mathrm{Cl}}^{-}$, ${\mathrm{Br}}^{-}$) were studied. Structural optimization and geometry relaxation using DFT methods reveal that replacing a boron atom with Al or N leads to altered bond lengths, and charge distribution in the nanocage. The results reveal that doped B38 with positive Gibbs free energy of the cell (6.27 kcal/mol for AlB₃₇, and 3.74 kcal/mol for B₃₇N) and negative cell voltage (-0.27 V for AlB₃₇, and −0.16 V for B₃₇N) make electrochemical reaction is unfavorable under the current conditions. Encapsulation of halides showed promise in enhancing the cell voltage for Li-ion battery applications, with Li/${\mathrm{Cl}}^{-}$-B₃₈ (3.40 V), Li/${\mathrm{Br}}^{-}$-B₃₈ (3.32 V), and with Li/$F^{-}$-B₃₈ achieving the highest cell potential of 3.49 V. Encapsulated nanocages exhibit changes in interaction energy values with Li/Li⁺, suggesting potential for use as anodes in Li-ion batteries.