A dispersion-corrected DFT study on adsorption of battery active materials anthraquinone and its derivatives on monolayer graphene and h-BN

Abstract

9,10-Anthraquinone (AQ) and its derivatives, i.e., benzofuro[5,6-b]furan-4,8-dione (BFFD), benzo[1,2-b:4,5-b′]dithiophene-4,8-dione (BDTD) and pyrido[3,4-g]isoquinoline-5,10-dione (PID), are environmentally friendly and cheap electrode materials. However, their significant solubility in electrolyte solutions limits the cycle performance of lithium-ion batteries. In this work a comparative investigation of these four organic molecules adsorbed on monolayer graphene and hexagonal boron nitride (h-BN) has been carried out using van der Waals (vdW) dispersion-corrected density-functional theory (DFT). The calculated results indicate that the vdW dispersion contributes to more than 80% of the total attractive interaction for all the complexes studied. The binding energies range from 1.06 to 1.31 eV, showing strong physisorption. The calculated binding energies of the four organic molecules are in the order: BFFD < BDTD < AQ < PID on monolayer graphene and BFFD < BDTD < PID < AQ on monolayer h-BN. The physisorption causes a work function shift relative to the isolated graphene or h-BN nanosheet in the order: AQ < BDTD < BFFD < PID on both the graphene and h-BN nanosheets. This sequence is dominated by the work functions of the four organic molecules. The strong physisorption suggests that the solubility of the four organic compounds in the electrolyte solutions can be reduced by binding them to a graphene or h-BN nanosheet, making the organic compound–graphene or organic compound–h-BN composite a promising electrode material for lithium-ion batteries.