A Density Functional Theory Study on the Thermodynamic and Dynamic Properties of Anthraquinone Analogues Cathode Materials for Rechargeable Lithium Ion Batteries
Organic redox compounds have become emerging electrode materials for rechargeable lithium ion batteries. The high electrochemical performance provides organic electrode materials with great opportunities to be applied in electric energy storage devices. Among different types of organic materials, conjugated carbonyl compounds are the most promising type of the present, because only they can achieve simultaneously high energy density, high cycling stability, and high power density. In this work, a series of heteroatoms substituted anthraquinone (AQ) derivatives are theoretical designed so as to remain the high theoretical capacity of AQ. The discharge and charge mechanism as well as the thermodynamic and dynamic properties of AQ and its derivatives have been investigated by first-principle density functional theory. By heteroatoms substitution, both the thermodynamic and dynamic properties of AQ as cathode materials can be largely improved. Among these conjugated carboxyl compounds, BDOZD and BDIOZD with simultaneously high theoretical capacity and high working potential, exhibit the largest energy density of about 780 Wh kg−1, which is 41% larger than that of AQ; PQD with the smallest value of λoIT gives the largest charge transfer rate constant, which is about 4 times as large as the prototype molecule AQ. The most interesting founding is that the Li-ion transfer plays a very important role in influencing both the discharge potential and electrochemical charge transfer rate. The present study illustrate that theoretical calculations provide a highly effective way to discover potential materials for rechargeable lithium ion batteries.