A new strategy for the morphology-controlled synthesis of Ni/Co MOFs for high-performance asymmetric supercapacitors. (May 2023)

• Record Type: Journal Article
• Authors: Radhika, M.G.; Srilakshmi, R.; Tejashree, V.; Venkatesh, Krishna; Sudha Kamath, M.K.; Nagaraju, Kathyayini
• Is Part Of: Journal of energy storage. Volume 61(2023)
• Publication Date: 2023-05
• Subjects: Ni/Co-MOFs -- Morphological properties -- Asymmetric supercapacitors -- Specific energy -- Specific power; Energy storage -- Periodicals; Energy storage -- Research -- Periodicals; 621.3126
• DOI: 10.1016/j.est.2023.106766
• Languages: English
• ISSNs: 2352-152X

Abstract

Abstract: Ni & Co based Metal-Organic Frameworks (MOFs) with different Ni & Co ratios 1:1, 2:1, 1:2 - NCs were synthesized using Trimesic acid as linker by solvothermal process, and the same were abbreviated as NC(1:1), NC(2:1) and NC(1:2) respectively. All the samples were analysed by analytical techniques such as Powder X-ray diffraction (P-XRD), Fourier Transform-Infrared Spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET) surface area, Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM) techniques. Morphological variations in NCs were observed from SEM images as ultrathin nanoflakes (NC(1:1) ) dandelion (NC(2:1) ) and nano-spikes (NC(1:2) ) due to the space coordination effect. Further, NCs were checked for their electrochemical performances in both three and two-electrode systems. Among NCs, NC(1:1) exhibited remarkable specific capacity of 172C g −1 @ 2.5 A g −1 in 1 M KOH solution. Asymmetric coin cell - ACC (CR-2032) constructed using NC(1:1) and commercially purchased AC in 1 M KOH solution, exhibited a high specific capacity of 92C g −1 @ 1 A g −1 with corresponding specific energy (SE) of 23 Wh kg −1 & specific power (SP) of 90 W kg −1 . The coin cells indicated 20, 000 cycles stability with 90 % specific capacity retention at 5000th cycle, however it was decreased to 47 % at the end of 20, 000th cycle. The self-discharge of ACC was also investigated by estimating open circuit voltage decay and interestingly the decay was only 20.4 mV h −1 after 48 h. Two-coin cells, each charged to 0–1.8 V were connected in series and utilized for its potential flashlight application in powering 12 white LEDs for 2 min. Graphical abstract: Unlabelled Image Highlights: Effect of weight ratio of Ni/Co in MOFs exhibited - exclusively different morphological properties. NC(1:1) demonstrated nano sized ultra-thin flakes morphology with better supercapacitance performance in 1 M KOH. Asymmetric coin cell- NC(1:1) //AC with potential (0–1.8 V) indicated 92C g −1 @ 1Ag −1 . ACC showed 20, 000 cycles stability at 25 Ag −1 with retention of 47 % and SE of 23 Whkg −1 . Two ACCs connected in series were utilized in powering 12 white LEDs for flashlight applications.