2D Nitrogen-Containing Carbon Material C5N as Potential Host Material for Lithium Polysulfides: A First-Principles Study

Two-dimensional (2D) materials are identified to be efficient in many applications. In this work, a novel 2D nitrogen-containing carbon material, C5N, is theoretically designed through structure changes in atomic scale, that is, introducing V-C-V-N bivacancy defects along lines in perfect C3N monolayer. C5N monolayer is verified to be chemically, mechanically, dynamically, and thermodynamically stable based on cohesive energy, elastic constants, phonon spectrum, and molecular dynamics calculations. C5N is determined to be metallic which is an important property for battery electrode. Moreover, the anchoring performance of S-8 and Li2Sn (n = 1, 2, 4, 6, and 8) on C5N monolayer and the anchoring mechanisms are explored. The adsorption energies are calculated to be -0.24, -1.20, -1.10, -1.06, -1.63, and -1.59 eV for S-8, Li2S8, Li2S6, Li2S4, Li2S2, and Li2S, respectively. The anchoring effect of Li2Sn on C5N monolayer originates from the charge transfer between lithium polysulfides and C5N surface. These results reveal that C5N monolayer is a promising host material for polysulfides in Li-S batteries. Our calculations illustrate the design of nanostructures and facilitate the application of carbon-based 2D materials in environment and energy.