Interpenetrated and Polythreaded Co^II-Organic Frameworks as a Supercapacitor Electrode Material with Ultrahigh Capacity and Excellent Energy Delivery Efficiency

Synthesizing kinetically stable coordination polymers (CPs) through ligand functionalization can effectively improve their supercapacitive performances. Herein, we have successfully synthesized three novel and topological Co-CPs by varying the flexible N-donor ligand and inorganic anions, namely, interpenetrated [Co(HTATB)(o-bib)]·H2O, extended two-dimensional (2D) layered Co(HTATB)(m-bib)·2H2O, and three-dimensional (3D) Co(HTATB)(m-bib), where bib is the flexible N-donor bis((1H-imidazol-1-yl)methyl)benzene linker (where o- and m- refer to ortho and meta positions, respectively) ligand and HTATB is the partial deprotonation mode from 4,4′,4″-s-triazine-2,4,6-triyl-tribenzoic acid. Various Co-CPs have been directly applied in the field of supercapacitors. All these framework materials exhibit high capacitance, excellent energy delivery efficiency, and good cycling performance. For instance, the maximum specific capacitance for penetrated 3D networks is 2572 F g–1 at 2.0 A g–1, and the mean energy delivery efficiency is up to 92.7% based on the tested current densities. Compared with extensional 2D layered and 3D networks, the 3D interpenetrated and polythreaded architectures could provide more active sites and thus promote fast charging and discharging processes. Furthermore, the Li+ uptake–release abilities of the Co-based CPs are also investigated, and the initial discharge capacity value for the 3D interpenetrated structures can reach up to 1792 mA h g–1 at a current density of 50 mA g–1.