Ligand amount-dependent growth of cobalt compounds derived from zeolitic imidazolate framework-67 as effective electroactive materials of energy storage device
Journal
Journal of Energy Storage
Journal Volume
93
ISSN
2352-152X
Date Issued
2024-07-15
Author(s)
Xiang-Yu You
Pin-Yan Lee
Subbiramaniyan Kubendhiran
Rei-Jei Chung
Chutima Kongvarhodom
Muhammad Saukani
Sibidou Yougbaré
Hung-Ming Chen
Yung-Fu Wu
Lu-Yin Lin
DOI
10.1016/j.est.2024.112319
Abstract
Zeolitic imidazolate framework-67 (ZIF-67) derivatives are designed with large surface area, high porosity and numerous redox states, which are beneficial for an efficient active material for charge storage. Incorporating structure directing agents (SDA) such as ammonium fluoroborate (NH4BF4) or ammonium bifluoride (NH4HF2) during synthesis is one of the effective methods for designing ZIF-67 derivatives. To simplify the environment and understand the function of fluorine-based complex, it is worthy to use a single metal precursor and 2-methylimidazole (2-Melm) to synthesize ZIF-67 derivatives. In this work, a novel cobalt precursor, cobalt tetrafluoroborate (Co(BF4)2), is used as the cobalt source and SDA to design new ZIF-67 derivatives (CoMel) for energy storage. Effects of Co(BF4)2 and 2-Melm ratios on material and electrochemical properties of CoMel are investigated. The optimal CoMel electrode shows a specific capacitance (CF) of 605.5 F/g at 20 mV/s, owing to large contacts to electrolyte with sheet-like structures and favorable cobalt compound compositions. A battery supercapacitor hybrid composed of the optimal CoMel electrode and the carbon electrode presents a maximum energy density of 45 Wh/kg at the power density of 410 W/kg. Excellent long-term stability with the CF retention of 95% and Coulombic efficiency of 98% after 7000 charge/discharge cycles are also achieved for this system. The novelty is to propose a single cobalt precursor as both cobalt ion source and SDA to design efficient active materials for energy storage. The same concept can be further used in other metal compounds for electrochemical applications.
Subjects
2-Methylimidazole
Cobalt tetrafluoroborate
Coulombic efficiency
Energy density
Structure directing agent
Zeolitic imidazolate framework-67
SDGs
Publisher
Elsevier BV
Description
Article number 112319
Type
journal article