Cobalt disulfide/carbon nanofibers with mesoporous heterostructure and excellent hydrophilicity for high energy density asymmetric supercapacitor

• Published in: Nano research 2023-07, Vol.16 (7), p.10401-10411
• Main Authors: Liu, Wenjie, Qiao, Fen, Yang, Jing, Yuan, Jiaren, Xie, Yi, Wang, Tao, Hu, Jinzhi, Zheng, Jihua, Ren, Rui, Kang, Xiaomin, Zhao, Yan, Zhang, Jiangwei
• Format: Article
• Language: English
• Subjects: Activated carbon; Asymmetry; Atomic/Molecular Structure and Spectra; Batteries; Biomedicine; Biotechnology; Capacitance; Carbon; Carbon fibers; Chemistry and Materials Science; Cobalt; Composite materials; Condensed Matter Physics; Contact angle; Density functional theory; Electrochemistry; Electrode materials; Electrodes; Energy storage; Heterostructures; Hydrophilicity; Ion diffusion; Lithium; Lithium sulfur batteries; Lithium-ion batteries; Materials Science; Nanofibers; Nanoparticles; Nanotechnology; Negative ions; Polyethylene glycol; Pore formation; Pore size; Reaction kinetics; Rechargeable batteries; Research Article; Specific capacity; Stability; Sulfur; Supercapacitors
• ISSN: 1998-0124; 1998-0000
• DOI: 10.1007/s12274-023-5533-1

Herein, a unique mesoporous heterostructure (average pore size: 15 nm) cobalt disulfide/carbon nanofibers (CoS 2 /PCNFs) composite with excellent hydrophilicity (contact angle: 23.5°) is prepared using polyethylene glycol (PEG) as a pore-forming agent. The CoS 2 /PCNF electrode exhibits excellent cycle stability (95.2% of initial specific capacitance at 10 A·g −1 after 8000 cycles), good rate performance (46.5% at 10 A·g −1 ), and high specific capacity (86.1 mAh·g −1 at 1 A·g −1 , about 688.8 F·g −1 at 1 A·g −1 ). Density functional theory (DFT) simulation elucidates that CoS 2 tends to transfer substantial charges to CNF. As the center of positive charge, CoS 2 is more likely to capture negative ions in the electrolyte, thus accelerating the ion diffusion process. The excellent properties of the electrode material can not only accelerate the electrochemical reaction kinetics, but also provide abundant redox-active sites and a high Faradaic capacity for the entire electrode due to the synergistic contributions of CoS 2 nanoparticles, mesoporous heterostructure of PCNF, and admirable hydrophilicity of the composite material. A CoS 2 /PCNF-0.25//AC (AC: activated carbon) asymmetric supercapacitor is assembled using CoS 2 /PCNF-0.25 as the positive electrode and AC as the negative electrode, which possesses a high energy density (35.5 Wh·kg −1 at a power density of 824 W·kg −1 ) and superior cycling stability (maintaining over 98% of initial capacitance after 2000 cycles). In addition, the unique CoS 2 /PCNF electrode is expected to be widely used in other electrochemical energy storage devices, such as lithium-ion batteries, sodium-ion batteries, lithium-sulfur batteries, etc.