Low-strained carbon monolayers with pentagonal cycles for lithium storage: Precursor analysis, self-assembly simulation and properties prediction

We formulated general requirements for hydrocarbon precursors that can easily self-assemble into a defect-free 2D monolayer on a metal substrate by a one-stage process. Based on these requirements, we proposed two suitable precursors contained pentagonal cycles, which were computationally characterized. Classical molecular dynamics shown that they can self-assemble on Cu(111) and Au(111) substrates under ambient conditions, while self-assembly on Ag(111) requires elevated temperature. Probable defect appearing during self-assembly was detected. The resulting 2D monolayers have pores about one nanometer in diameter. Nevertheless, they exhibit high structural stability and metallic conductivity. According to density functional theory calculations, they can be elastically deformed by about 8%, and their elastic constants are comparable to those of graphynes. The presence of pores in the carbon monolayers allows the adsorption of up to 17.2 at. % lithium. Ab initio molecular dynamics confirms the reliable loading of lithium on the monolayers. The presence of pores, absence of highreactive multiple C-C bonds or strained triangle/square cycles as well as excellent adsorption properties are the main advantages of the proposed monolayers in comparison with graphene and its common allotropes.