Self-Assembled Cobalt–Nickel Bimetallic-Organic Framework Materials with High Supercapacitor Performance
Dan Wu, Qiyao Zhang, Man Zhang, Jiandong Yang, Jiandong Yang, Jie Yang, Jie Yang, Tuoping Hu, X. Wang
Abstract
Two new metal–organic frameworks (MOFs), [Co(bcpp)(bbip)]·H 2 O (Co-MOF) and [Ni(bcpp)(bbip)]·H 2 O (Ni-MOF), have been generated based on a V-type flexible carboxylic ligand 3,5-bis(4-carboxyl phenoxy) pyridine (H 2 bcpp) and a rigid N-donor ligand 1,1′-(1,4-phenylene)bis(1 H -benzimidazole) (bbip) by a solvothermal method. Co-MOF and Ni-MOF are isostructural with a 2-fold interpenetrated layered structure. Moreover, a series of bimetallic Co x Ni y -MOFs ( x / y = 1:1, 2.5:1, 2.75:1, 3:1, 3.25:1, and 3.5:1) were obtained by using one-pot synthesis. Owing to their mixed metallic components and internal layered structure, the bimetallic Co x Ni y -MOFs possess a remarkable electrochemical storage property. Significantly, the Co 2.75 Ni 1 -MOF has high specific capacitance (699 F g –1 ) at 0.5 A g –1 and good cycling durability (retained 72.7% over 3100 turns). Additionally, an asymmetrical ultra-capacitor based on Co 2.75 Ni 1 -MOF and activated carbon (AC) delivers a maximum energy density of 20.44 Wh kg –1 at 387.49 W kg –1 and a high cycle-to-cycle stability with 85.4% of the primary capacitance over 15,000 turns.