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

• Published in: ACS applied energy materials Vol. 4; no. 11; pp. 12466 - 12478
• Main Authors: Thirugnanasambandam, Eswaramoorthi, Shanmugam, Ganesan, Selvaraj, Balamurugan, Kamaraj, Santhosh
• Format: Journal Article
• Language: English
• Published: American Chemical Society 22.11.2021
• Subjects: Co-redox pair electrolyte; RCSC and DSSC device; octahedron structure; high specific capacitance; Co-MOF electrodes
• ISSN: 2574-0962; 2574-0962
• DOI: 10.1021/acsaem.1c02298

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 (J sc = 4.73 mA cm–2), and open circuit voltage (V oc = 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.