Quantum-Dot-Based Carbon Nanotubes: Design, Doping, and Lithium Storage for High-Capacity Energy Applications

In this article, we present the design of novel nanotubes exhibiting quantum confinement and edge effects derived from graphene quantum dots. Density functional theory (DFT) and molecular dynamics simulations were utilized to explore their structural, electronic, and energy storage properties. These finite graphene nanotubes demonstrate both structural and thermal stability, as confirmed by frequency and molecular dynamics (MD) simulations at elevated temperatures (400 K). Electrical conductivity is significantly enhanced through boron and nitrogen doping, attributed to a notable reduction in the energy gap (2.49 → 0.4 eV). Furthermore, these nanotubes exhibit intriguing interactions with lithium (Li) metal atoms, where the adsorption strength increases monotonically with the number of Li atoms adsorbed. Structural analyses reveal minimal deformation upon Li adsorption, especially in nitrogen-modified nanotubes. Consecutive energy calculations were employed to estimate the maximum number of Li atoms that can be adsorbed. Our findings show that the nanotubes can accommodate Li atoms in three distinct layers, achieving an exceptional storage capacity of 2295.3 mAh g^-1, significantly surpassing established materials like graphene, and comparable to lithium metal, but without the risk of dendrite formation. This extraordinary theoretical storage capacity, coupled with minimal structural deformation and excellent thermal stability confirmed by MD simulations, suggests that these quantum nanotubes are highly promising for high-capacity lithium-ion batteries and next-generation energy storage technologies.