Graphene-enhanced electrodes for scalable supercapacitors. (10th December 2017)

• Record Type: Journal Article
• Authors: Tsai, I-Ling; Cao, Jianyun; Le Fevre, Lewis; Wang, Bin; Todd, Rebecca; Dryfe, Robert A.W.; Forsyth, Andrew J.
• Is Part Of: Electrochimica acta. Volume 257(2017)
• Page Start: 372
• Page End: 379
• Publication Date: 2017-12-10
• Subjects: Scale-up -- Graphene pouch cell -- Activated carbon -- Supercapacitor -- High-power; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2017.10.056
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: A scale-up process of high-rate-capability supercapacitors based on electrochemically exfoliated graphene (EEG) and hybrid activated carbon (AC)/EEG are studied in this work. A comparison of the rate capabilities of large-scale EEG and AC/EEG-based pouch cell and commercial high-power supercapacitors are also presented in this paper. The oxygen content of the EEG used in this work is 9.6 at%, with a C/O ratio of 9.36, and the electrical conductivity is 2.68 × 10 4 Sm −1 . The specific capacitance (59 Fg −1 ) of the EEG-based supercapacitors remained above 80% of the maximum value as the scan rate was increased from 5 mVs −1 to 1 Vs −1 . Furthermore, our study reveals how the rate capability of activated carbon (AC) based supercapacitors can be improved by adding EEG into the electrodes to form a hybrid AC/EEG supercapacitor. Both the EEG-based and AC/EEG supercapacitors were scaled-up to pouch cells with capacitances of tens of farads. The electrochemical response was unchanged when scaling up from a coin cell to a pouch cell, although the specific capacitance fell slightly. The cycle performance of the AC/EEG pouch cell showed good long-term stability, with better than 95% capacitance retention after 10, 000 cycles. Both the EEG and AC/EEG (with 1:1 mass ratio) pouch cells had rate capabilities that compared favourably with the commercial high-power supercapacitors.