First Principle Investigation of C606 Molecule Absorption on Graphene As 2D Eco-Electrode of Lithium-Ion Battery

Abstract

: The use of organic electrodes draws more attentions recently as its synthesis and disposal are both environment-friendly. The oxocarbon salt Li2C6O6 and tetralithium salt Li4C6O6 bulk organic materials have been prove to be efficient by Chen et al. Even these renewable materials exhibit good cycling and rate abilities and have specific capacity of upmost 580 mAhg-1. However, the drawback such as low output voltage and soluble organic molecules are also obvious. On the other hand, graphene is known as a 2D crystal structure with atomic thickness and marvelous electronic structure and high mechanical strength. Hence we here propose a novel combination of graphene and C6O6 molecules. The coverage rate is set to every single C6O6 molecule @6*6 graphene supercell to avoid the possible interaction of neighbor molecules. Three kinds of high symmetrical positions are developed and labeled as AA, AB and AB-r. In our DFT calculation containing vdW force effect, Li atoms are set at Top(T), Hollow(H) and Bridge(B) site of these structures separately. And by viewing the evolution of Li atoms and comparing the final energies of nearly 70 types of positions, we note that Li atom is favorable to function with carbonyl group in all three structures. Moreover, graphene works as a stabilizer in this system, which is believed to increase the cycling capability of this electrode. We also demonstrate that the electron of Li atom prefers to transfer to C6O6 molecule instead of graphene from partial charge density calculations. Keyword: Li-ion battery, DFT, C6O6, graphene. Figure 1