Enabling Enhanced Lithium Ion Storage Performance of Graphdiyne by Doping with Group-15 Elements: A First-Principles Study.

As a typical two-dimensional material possessing sp and sp hybrid orbitals, graphdiyne (GDY) and its derivatives have been proposed as an attractive candidate for high-performance lithium ion batteries (LIBs). In this work, an advanced GDY LIB electrode is designed by doping with group-15 elements. With the aid of first-principles simulations, the geometric properties, electronic structures, theoretical storage capacities, open-circuit voltages, and diffusion path of Li atoms on doped GDY are comprehensively investigated. Specifically, 14 different adsorption sites are proposed, most of which are situated out of plane of the carbon network, resulting from the out of plane Pz orbitals of conduction band minimum and valence band maximum. Among the five doped GDY, phosphorus-doped graphdiyne (P-GDY) exhibits prominent lithium ion storage behavior, i.e., the maximum theoretical capacity is 1949 mA·h·g, which is ∼2.6 times higher than that of GDY. Moreover, calculation results in terms of the in-plane migration of lithium ion on P-GDY indicate that Li atoms prefer to diffuse across the carbon network (with a moderate barrier of 0.46 eV) rather than directly through the middle of the hexagonal aperture (with a higher barrier of 1.78 eV). Thus, this approach provides novel insights into the Li ion storage properties of group-15 element-doped GDY from the prospect of theoretical calculations, which would be useful to guide the future design of high-capacity GDY anodes for LIBs.