Innovative Construction of the Cobalt Metal Complex Redox Electrolyte and Octahedron Structure of the Cobalt Metal Organic Framework Electrode in the Energy Storage and Energy Conversion System

One of the most important tasks in improving supercapacitor (SC) efficiency is the quest for advanced electrode and electrolyte materials. For the first time, we propose using a metal organic framework (MOF) as an electrode and a cobalt redox pair as an electrolyte to increase the cell voltage of a SC. We successfully synthesized the octahedron structure of the cobalt MOF using a simple annealing treatment process, and we prepared a Co-redox couple incorporated along with the KOH electrolyte for the fabrication of a SC and dye-sensitized solar cell (DSSC). The redox couple-aided N-MOF exhibits an excellent electrochemical performance that is attributed to the highest specific capacitance value of 1150.61 F g–1 (517.77 C g–1) and capacitance retentions of 98.4% in the three-electrode system. Meanwhile, it shows 98.4 F g–1 in a two-electrode system at 1 A g–1 in current density. The two-electrode system redox couple-aided SC device had reached a high energy density of 70.8 W h kg–1 with a power density of 515.75 W kg–1. At the same time, it showed good cyclic stability and could retain 94.3% of the initial capacitance after 11,200 charge and discharge cycles. The DSSC devices were fabricated using N719 dyes coupled with the Co2+/3+[npbi]3 redox pair as an electrolyte and Co-MOF as a counter electrode, which exhibits a short circuit current (Jsc = 4.73 mA cm–2), and open circuit voltage (Voc = 0.25 V), which gives a power conversion efficiency of 0.33% under 1 sun illumination with AM 1.5 G. The combination of the N-MOF electrode material with a Co-redox mediator paved the way to improve the efficient material for energy conversion of DSSCs and energy storage of SCs.