Quantum Chemical Modeling of the Adsorption of Crown Ethers of Different Structures on Surfaces of Lithium and Carbon

Abstract

Theoretical studies are performed of the adsorption of crown ethers of different structures (15‑crown-5, dibenzo-18-crown-6 and 3-pentadecyl-2,4-dioxo-16-crown-5) on surfaces of lithium and carbon, the main anode materials in secondary lithium power sources. The energies of adsorption of these crown ethers and the bonding energies of lithium ions with crown ether in the free and adsorbed states are calculated using the PBE density functional. It is shown that the molecules of 15-crown-5 and 3-pentadecyl-2,4-dioxo-16-crown-5 form flat structures, contributing to the stack folding of subsequent crown ether molecules. There are steric hindrances for dibenzo-18-crown-6, since one of the benzene rings is oriented perpendicularly. It is found that 3-pentadecyl-2,4-dioxo-16-crown-5 promotes the transfer of lithium ion from the electrolyte volume to the surface of both lithium and carbon better than the other two crown ethers.