Understanding the lithiation mechanisms of pyrenetetrone-based carbonyl compound as cathode material for lithium-ion battery: Insight from first principle density functional theory

Abstract

Regardless of the lithium-ion batteries (LIBs) promising electrochemical storage performance, only limited studies have been reported using theoretical calculations on the mechanism of interactions between carbonyl functional groups and lithium-ions in a carbonyl-based LIBs. Despite such efforts, a systematic study on the lithiation mechanism of carbonyl-based structure for designing cathode electrode material with well-defined step-by-step lithiation process aiming at optimum electrochemical performances is still a challenge. Herein, the electronic structure, reactivity, topological, and the electrochemical mechanistic performances of pyrenetetrone-based carbonyl compound was reported based on the Density Functional Theory (DFT) calculations at the B3LYP/6-31+G (d, p) basis set. Four different configurations of the studied compound designated based on the lithiation; LiA, Li2A, Li3A, and Li4A were computationally modelled using the experimentally studied structure. The computed HOMO-LUMO energy gaps showed that Li3A has the highest energy gap and hence more stable compared to other compounds. Comparatively, our theoretical data strongly correlated with the experimental results of the synthesized structure of pyrenetetrone having a slight energy difference of 0.2eV. The chemical quantum descriptors showed that Li3A has greater tendency to accept electrons while Li2A is the best electron donor. Again, the quantum theory of atoms-in-molecules (QTAIM) topological analysis showed that interactions between O24–Li28 has the highest electron density of 0.0515e. The reduction potential increased as the bound Li atoms are added but decreased at the fourth lithiation (Li4A). The reduction potential of the experimentally synthesized pyrenetetrone is in good agreement with the theoretical calculated results and the higher value of redox potential of Li3A is attributed to its high lithium binding energy of 129.33 kcal/mol. Thus, our work reveals an optimistic strategy for designing and utilizing these materials in the fabrication of highly efficient carbonyl base organic redox materials for lithium ion battery.