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

Abstract

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.

Energy Enhancement of a Nickel–Cobalt-Mixed Metallic Metal–Organic Framework Electrode and a Potassium Iodide Redox Mediator Bound with an Aqueous Electrolyte for High-Performance Redox-Aided Asymmetric Supercapacitors

“…Huang et al eventually identified the crystal structure of the nickel−cobalt-mixed MOF through the use of comprehensive Rietveld refinement and ab initio powder XRD techniques. 21 The crystal data published by Huang et al show that the sample's experimental XRD patterns exactly match the modeled ones. Figure 2c shows the crystal structure of the prepared CNN-MOF, CNH-MOF, and CNT-MOF, in which the anchoring organic groups (naphthalene, tricarboxylic, and terephthalate) are directly attached to the sandwich structure between the nickel and cobalt metal layer along the aaxis.…”

“…Additionally, Ni/Co-MOF samples in various ratios have the same crystalline structure. Huang et al eventually identified the crystal structure of the nickel–cobalt-mixed MOF through the use of comprehensive Rietveld refinement and ab initio powder XRD techniques . The crystal data published by Huang et al show that the sample’s experimental XRD patterns exactly match the modeled ones.…”

“…According to the equation below, the constructed two electrode’s calculated Coulombic efficiency (η) is approximately the performance of the GCD stability η = ( t d t c ) × 100 % where the terms t c “charging time” and t d “discharge time” are used.…”

“…Most tasks in supercapacitor applications may now be made more energy efficient if two methods for increasing the cell voltage are used . (i) Electrode material development with huge capacitance, such as metal oxide materials and carbon-based materials. − (ii) Redox substance bound with aqueous or alkali electrolytes is another way of enhancing the capacitance performance. Redox mediator electrolytes enhance the redox potential and fast ion transport between negative electrodes and positive electrodes.…”

A Newly Synthesized Copper Redox Couple Electrolyte with Activated Carbon Electrode from Samanea saman Wood Tissue for Flexible Supercapacitor

“…The energy efficiency was computed from charge–discharge curves according to the following equation: Charge and discharge are denoted by E Int / C and E Int / D , respectively.…”