Li-Binding Thermodynamics and Redox Properties of BNOPS-Based Organic Compounds for Cathodes in Lithium-Ion Batteries.

Cyclic organic compounds with pentagon rings have been paid less attention for cathodes in lithium-ion batteries as compared with aromatic compounds. In this study, we investigate the Li-binding thermodynamics, redox properties, and theoretical performance for a selected set of heteroatom-containing, pentagon-shaped, organic compounds, namely borole, pyrrole, furan, phosphole, thiophene, and their derivatives to assess their potential for organic cathode materials. This investigation provides us with three important findings. First, the Li-binding thermodynamics and redox properties for the organic compounds would be systematically tailored by the type of the incorporated heteroatom and backbone length, exhibiting both the strongest Li-binding and the highest redox potential for borole. Second, it is highlighted that borole can store up to two Li atoms per molecule exhibiting the exceptionally high charge capacity (839 mA h/g) despite the absence of any well-known redox-active moieties (e.g., carbonyl). Third, dibenzothiophene exhibits weak and comparable Li-binding strengths at multiple feasible binding configurations with an indication of its low Li-storage capability, while the others dominantly bind with Li at their most stable binding configurations. All these findings will provide an insight into the guidelines for the systematic design of promising heterocyclic organic compounds (i.e., borole-based insoluble polymeric forms) for cathodes in secondary batteries.