β -naphthyldiene: A novel multifunctional 2D material for energy storage applications

This study presents the novel β -naphthyldiene ( β -NPD) monolayer, derived from β -naphthylene through the incorporation of an additional cyclobutadiene ring between naphthyl segments, forming a distinctive 14-, 6-, and 4-membered rings configuration. The structural, mechanical, and thermal stability of the β -NPD monolayer were rigorously assessed via density functional theory (DFT) simulations. Belonging to the Cmmm space group, the β -NPD monolayer exhibits lattice parameters a = 10 . 33 Å and b = 9 . 27 Å, with a band gap energy of 0.02 eV (PBE) and 0.15 eV (HSE). Its mechanical properties include Young’s modulus ranging from 105.84 N/m to 211.89 N/m, a shear modulus between 53.07 N/m and 64.70 N/m, and a Poisson’s ratio spanning 0.22 to 0.50, indicating notable anisotropy. The β -NPD monolayer shows excellent utility in energy storage applications. It achieves a high lithium storage capacity of 957.18 mAh/g without structural degradation, providing a promising solution for lithium-ion batteries (LIBs). Additionally, the lithium-decorated β -NPD monolayer exhibits an exceptional theoretical hydrogen storage capacity of 19.80 wt%, surpassing many recently reported 2D materials. These findings highlight the β -NPD monolayer as a highly versatile material with significant potential for advancing energy storage technologies.