Abstract
This work adopts an efficient chemical-wet method to build a three-dimensional (3D) carbon composite as an electrode material for high-performance supercapacitors (SCs). Carbon dots (CDs), prepared by thermal pyrolysis of citric acid and urea under microwaves at 280 °C, are homogeneously coated onto lignin-based activated carbons (ACs), thus forming the 3D composites possessing an interior surface decorated with CD binding sites. Benefiting from the hydrophilicity and ultrafine size of CDs, the affinity of the electrode surface toward aqueous electrolytes is significantly improved with the addition of CDs, leading to the enhanced effective surface area (i.e., abundant electroactive sites) and a decreased ionic diffusion path. The capacitance of the SCs is improved from 125.8 to 301.7 F g-1 with CD addition. The SC with CD addition possesses improved cycle stability with a coulombic efficiency around 100% after 3000 cycles. After cycling, the ion diffusion coefficient of the CD@AC-11 electrode is enhanced by 25.5 times as compared to that of the pristine AC one. This unique and robust carbon framework can be utilized for engineering the desired pore structure and micropore/mesopore fraction within the AC electrodes. This strategy of CD@AC electrodes demonstrates a promising route for using renewable porous carbon materials in advanced energy-storage devices.
| Original language | English |
|---|---|
| Pages (from-to) | 7851-7861 |
| Number of pages | 11 |
| Journal | ACS Omega |
| Volume | 6 |
| Issue number | 11 |
| DOIs | |
| State | Published - Mar 23 2021 |
Funding
The authors would like to thank Dr. John Dunlap and Dr. Gerd Duscher (Joint Institute for Advanced Materials) for their help and support for conducting the TEM measurements. The authors would also like to thank Kendhl Seabright (CRC UT-Knoxville) for conducting the CHNS measurements. The authors would also like to thank Dr. Tao Wu and Dr. Teng Li (Food science, UTIA) for their support for contact angle measurements. This research was supported by a grant from the U.S. Department of Energy BioEnergy Technologies Office through the Biomass Research and Development Initiative award DE-EE0008353.0000. D.P.H. acknowledges support from the USDA National Institute of Food and Agriculture Hatch Project 1012359.