Hierarchical Lignin-Based Carbon Matrix and Carbon Dot Composite Electrodes for High-Performance Supercapacitors

Lu Yu; Chien-Te Hsieh; David J Keffer; Hao Chen; Gabriel A Goenaga; Sheng Dai; Thomas A Zawodzinski; David P Harper

doi:10.1021/acsomega.1c00448

Hierarchical Lignin-Based Carbon Matrix and Carbon Dot Composite Electrodes for High-Performance Supercapacitors

ACS Omega. 2021 Mar 10;6(11):7851-7861. doi: 10.1021/acsomega.1c00448. eCollection 2021 Mar 23.

Authors

Lu Yu^{1

2}, Chien-Te Hsieh^{3

4}, David J Keffer², Hao Chen⁵, Gabriel A Goenaga⁶, Sheng Dai^{5

7}, Thomas A Zawodzinski^{6

8}, David P Harper^{1

2}

Affiliations

¹ Center for Renewable Carbon, Institute of Agriculture, The University of Tennessee, Knoxville, Tennessee 37996, United States.
² Department of Materials Science and Engineering, The University of Tennessee, Knoxville, Tennessee 37996, United States.
³ Department of Chemical Engineering and Materials Science, Yuan Ze University, Taoyuan 32003, Taiwan.
⁴ Department of Mechanical, Aerospace, and Biomedical Engineering, The University of Tennessee, Knoxville, Tennessee 37996, United States.
⁵ Department of Chemistry, The University of Tennessee, Knoxville, Tennessee 37996, United States.
⁶ Department of Chemical and Biomolecular, The University of Tennessee, Knoxville, Tennessee 37996, United States.
⁷ Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.
⁸ Physical Chem. Mater. Group, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.

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.