A Tetrakis(terpyridine) Ligand–Based Cobalt(II) Complex Nanosheet as a Stable Dual-Ion Battery Cathode Material

Inspired by the flexibility of the bottom-up approach in terms of selecting molecular components and thus tailoring functionalities, a terpyridine derivative (1,2,4,5-tetrakis(4-(2,2′:6′,2″-terpyridyl)phenyl)benzene) (Tetra-tpy) is synthesized and coordinated with Co(II) ion to self-assemble into a nanosheet Co-sheet by a facile interface-assisted synthesis. The bis(terpyridine)-Co(II) complex nanosheet formed not only shows good stability, but also features the layered structure and rich electrochemical activity inherited from the embedded Co(terpyridine)₂ motif. Thus, Co-sheet can serve as a cathode material for a dual-ion battery prototype, which exhibits a high utilization of redox-active sites, good cycling stability, and rate capability, thus expanding the potential application of this kind of easily prepared metal-complex nanosheets in the field of energy storage.