Enhanced Electrochemical Performance Of Bimetallic Doped Ni-Based Metal-Organic Frameworks By Redox Additives In An Alkaline Electrolyte

A Cu2+ and Zn2+ bimetallic doped metal-organic framework Ni-2(bdc)(2)(dabco) (CuZnNi-MOF, where bdc is 1,4-benzenedicarboxylic acid and dabco is 1,4-diazabicyclo[2.2.2]-octane), has been successfully synthesized by the solvothermal method. The carbon-held metal compound nanoparticles (MCN@C) and metal oxide composite (CuOZnONiO) were subsequently obtained by using the CuZnNi-MOF as the precursor. The electrochemical performance of the prepared samples was evaluated in an electrolyte with and without a redox additive (K4Fe(CN)(6)). The specific capacity of the samples tested in the electrolyte with Fe(CN)(6)(4-)/Fe(CN)(6)(3-) has a high value of 112.5 mA h g(-1) at 1 A g(-1), which is much higher than that measured in the electrolyte without the redox additive, indicating that the Fe(CN)(6)(4-)/Fe(CN)(6)(3-) redox couple can effectively enhance the electrochemical performance of electrode materials. An asymmetric supercapacitor (ASC) CuZnNi-MOF//PEDOT-AC (poly(3,4-ethylenedioxythiophene)-activated carbon) was further assembled and tested in 3 M KOH + 0.05 MK4Fe(CN)(6) electrolyte. The ASC shows a high energy density of 25.2 W h kg(-1), a maximum power density of 8 808 W kg(-1), and also superb cycling performance. Moreover, two assembled ASCs in series connection are found to be able to light up a red light-emitting diode for at least 20 min.