Nickel-based pillared MOFs for high-performance supercapacitors: Design, synthesis and stability study

We have successfully synthesized novel, nickel-based, pillared DABCO-MOFs (DMOFs) of similar topologies – [Ni(L)(DABCO)0.5], where L is the functionalized BDC (1,4-benzenedicarboxylic acid) linker and DABCO is 1,4-diazabicyclo[2.2.2]-octane. The stability of DMOF-ADC ([Ni(9,10-anthracenedicarboxylic acid)(DABCO)0.5]) and DMOF-TM ([Ni(2,3,5,6-tetramethyl-1,4-benzenedicarboxylic acid)(DABCO)0.5]) in a humid environment was confirmed by surface area analysis on the water-exposed samples. When used as electrode materials, these DMOF capacitors exhibited excellent electrochemical performance. For example, a Ni-DMOF-ADC electrode showed specific capacitances of 552 and 438 F g−1 at current densities of 1 and 20 A g−1, respectively, while maintaining outstanding cycling stability (capacitance retention of >98% after 16,000 cycles at current density of 10 A g−1) for MOF-derived materials based supercapacitors. The excellent electrochemical performance is attributed to the conversion of DMOFs to highly functionalized nickel hydroxide which inherited the high stability of DMOF-ADC and remained intact during charge-discharge process. Further, this work provides a general approach for the application of nickel-based pillared MOFs as relatively stable electrode in electrical energy storage.