DFT investigation of Li storage behavior of sceamless a-graphyne and b-graphyne nanotubes

Graphynes have great potential -as anode materials for lithium-ion batteries (LIBs) owing to their advanced structural and electronic properties. Previously, the curvature of g-graphyne folded into nanotubes (gGyNTs) caused a significant increase in its Li storage capacity and diffusion ability. Here, using density functional theory (DFT) calculations, we report the same curvature effect in a- and bgraphyne nanotubes (aGyNTs and bGyNTs), whose maximum storage capacities are predicted to be -up to 3488 and 3070 mAh/g, respectively, similar to that of pure Li (3861 mAh/g). Such high capacities are attributed to the graphyne nanotubes having larger specific surface areas and pores than those of other carbon materials. Additionally, climbing -image- nudged-elastic- band calculations reveal that Li atoms can diffuse almost freely through acetylenic rings on the concave side of the aGyNTs, indicating an excellent charge -discharge rate ascribed to weaker adsorption on the 18-membered ring than that on the 12-membered rings of the bGyNTs and gGyNTs. Our results suggest that the aGyNTs are promising as the anode material for LIBs with exceptional overall performance. This study also provides a strategy to design anode materials based on their curvature and topological morphology.(c) 2022 Elsevier Ltd. All rights reserved.