Synthesis of Hexaazatriphenylene Charge-Transfer Complexes and Their Application in Cathode Active Materials for Lithium-Ion Batteries

A rational strategy for constructing a packing structure with diffusion paths for lithium ions is a critical requirement in the development of organic cathode active materials. Charge-transfer (CT) complexes with columnar structures are prospective materials in this regard because the voids between the columns can serve as diffusion paths for lithium ions. In this study, four CT complexes with columnar structures were synthesized by utilizing the pi-pi interactions between an electron acceptor, namely, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (HAT-CN), and various electron donors (i.e., coronene, pyrene, anthracene, and carbazole). The structures of these complexes were determined by single-crystal X-ray diffraction measurements, and their suitability for use as cathode-active materials in lithium-ion batteries was evaluated. The CT complex composed of HAT-CN and coronene (CT-2) showed a high capacity (163.6 mAh g(-1) at a current density of 100 mA g(-1) in the first cycle), which was attributed to the strong aromatic interactions producing a stable columnar structure.