Study of Lithium Migration Pathways in the Organic Electrode Materials of Li-Battery by Dispersion-Corrected Density Functional Theory

摘要

Organic materials have been considered a promising alternative as electrodes for rechargeable lithium-ion batteries. However, there are some obvious shortcomings, especially poor dynamics. performance. Approaches to understand the reason for the poor dynamic performance are the main point of the present work. In this paper, an organic electrode material,Ci(2)H(4)N(4), is selected as a sample, and studied by dispersion-corrected density functional theory (DFT-D2). The calculation results show that the band gaps of delithiated and lithiated states are about 0.9 and 1.0 eV, respectively, which is consistent with the conventional conjugated organic materials implying the good electronic conductivity. The Li-ion migration pathway forms a complicated three-dimensional (3D) network The migration energy barrier is higher than 0.53 eV, Which is obviously higher than that of the inorganic electrode material, demonstrating the poor ionic conductivity. In organic materials, although the steric hindrance is lowered due to the large intermolecular spade) the coulomb potential is significantly improved at the same time, which is the main reason for the high energy barrier of Li-ion migration. Effective ways to lower the lithium migration energy barrier and improve the ionic Conductivity should be considered when synthesizing new organic electrode materials.