Home >
News > Supercapacitors of Nanocrystalline Metal-Organic Frameworks
Supercapacitors of Nanocrystalline Metal-Organic Frameworks
Summary:
The authors from University of California-Berkeley, Korea Advanced Institute of Science and Technology, Lawrence Berkeley National Laboratory, etc. developed nanocrystalline metal-organic frameworks (nMOFs) doped with graphene, achieving excellent performance in supercapacitor applications.
Background:
1. To address the issues of supercapacitors (carbon-based materials have low capacitance, metal oxides have short life cycles, porous polymers are prone to degradation) and the low capacitance of the only previously studied MOF (Co8-MOF-5) for supercapacitors, previous researchers focused on carbon, metal oxide and porous polymer materials, yet failed to balance high capacitance and long life.
2. The authors proposed synthesizing 23 types of nMOFs with varied structures/functionalities, doping with graphene, and obtained supercapacitors with high capacitance and long cycle life (e.g., nMOF-867 outperforms activated carbon).
Research Content:
1.Synthesis:
- nMOFs: Mixed metal salts (e.g., Zn(OAc)₂·2H₂O, Co(OAc)₂·4H₂O) with organic ligands (e.g., BDCH₂, DOTH₂) in DMF, via microwave-assisted solvothermal reaction or oven heating, followed by centrifugation, solvent washing and vacuum drying.
- nMOF films: Dispersed nMOFs with oleic acid in hexane, mixed with graphene/hexane dispersion, spin-coated on Ti substrates, and treated to remove oleic acid.
- Supercapacitors: Assembled nMOF films, separator and 1.0 M (C₂H₅)₄NBF₄/acetonitrile electrolyte into coin cells.
2.Characterizations:
1) BET: nHKUST-1 (1470 m²/g), nMOF-867 and others have porous structures; pore sizes vary (e.g., nUiO-66: 6.8-7.2 Å, nMOF-801: 5.4-7.0 Å).
2) SEM/TEM: nHKUST-1 (100 nm, 20% size distribution), nMOF-801 (100 nm), nMOF-801-L (500 nm); films are 2 μm thick with graphene distributed.
3) Electrochemical tests: nMOF-867 (stack capacitance: 0.644 F/cm³, areal capacitance: 5.085 mF/cm²; 10,000 cycles stable).
3.Application: Tested in supercapacitors; nMOF-867 shows energy density (6.04×10⁻⁴ Wh/cm³) and power density (1.097 W/cm³), 6x better than activated carbon.
4.Mechanism: nMOFs’ high porosity provides ion storage space; graphene enhances electron mobility; nMOF-867’s sp² nitrogen strengthens ion interaction, jointly improving performance.
Outlook:
This research realizes efficient application of nMOFs in supercapacitors, reveals structure-function relationships, and provides a new direction for high-performance electrochemical energy storage materials.
Supercapacitors of Nanocrystalline Metal-Organic Frameworks
Authors: Kyung Min Choi, Hyung Mo Jeong, Jung Hyo Park, Yue-Biao Zhang, Jeung Ku Kang, Omar M. Yaghi
DOI: 10.1021/nn5027092
Link: https://pubs.acs.org/doi/10.1021/nn5027092
The above review is for academic progress sharing. For any errors or copyright issues, please contact us for correction or removal.
