Investigating solvent effects on synthesizing novel cobalt hydroxide and fluoride complex from Co(BF4)2 as active materials of the battery supercapacitor hybrid
Journal
Journal of Colloid and Interface Science
Journal Volume
677
Start Page
502
End Page
511
ISSN
0021-9797
Date Issued
2025-01
Author(s)
Xiang-Yu You
Pin-Yan Lee
Su-Ching Wang
Chutima Kongvarhodom
Muhammad Saukani
Sibidou Yougbaré
Hung-Ming Chen
Yung-Fu Wu
Lu-Yin Lin
DOI
10.1016/j.jcis.2024.07.259
Abstract
Metal-organic framework (MOF) derivatives with tunable pore structure and improved conductivity are intensively designed as electroactive materials. Incorporating structure directing agents (SDA) is beneficial for designing MOF derivatives with excellent electrochemical performances. Ammonium fluoroborate has been reported as an effective SDA, coupled with cobalt salt and 2-methylimidazole, to synthesize zeolitic imidazolate framework-67 (ZIF-67) derivatives for charge storage. However, the synthetic environment for growing cobalt-based active materials is relatively complex. In this study, cobalt tetrafluoroborate (Co(BF4)2) is proposed as a novel cobalt precursor, supplementing cobalt ions and acting as the SDA in a single chemical, to synthesize the cobalt-based electroactive material of energy storage electrodes. Interactions between solvent molecules and solutes play significant roles on the morphology, composition, and electrochemical performance of active materials. Deionized water, methanol and ethanol are used as precursor solvents to understand their effects on material and electrochemical properties. The optimal electrode presents a specific capacitance of 608.3 F/g at 20 mV/s, attributed to the highest electrochemical surface area and evident compositions of cobalt fluoride and hydroxide. A battery supercapacitor hybrid achieves the maximum energy density of 45 Wh/kg at 429 W/kg. The CF retention of 100% and Coulombic efficiency of 99% are achieved after 10,000 cycles.
Subjects
Battery supercapacitor hybrid
Cobalt tetrafluoroborate
Metal–organic framework
Solvent
Structure directing agent
Zeolitic imidazolate framework-67
Publisher
Elsevier BV
Type
journal article