Introducing Electrochemically Active Oxygen Species to Boost the Pseudocapacitance of Carbon‐based Supercapacitor

Abstract

Low energy density is the main bottleneck for carbon‐based supercapacitors, which can be addressed by introducing extra faradaic pseudocapacitance. Herein, a cyclic voltammetry oxidation method in 1 M H2SO4 electrolyte was employed for carbon electrode to produce electrochemically active oxygen functional groups that are in contact with the conductive substrates, which facilitates the implementation of the pseudocapacitance. Moreover, the influence of potential window and sweep rate on the components and performances of oxidized electrodes in the cyclic voltammetry oxidation process was systematically investigated. The results reveal that a broad potential window of −0.65∼2 V can enhance the oxygen content to 16.4 wt.% (vs. 7.6 wt.% within −0.65∼1.5 V). Additionally, a selective oxygen component dominated with redox active C−OH and C=O groups was achieved by a rapid potentiodynamic sweep at 20 mV s−1, simultaneously suppressing the ‐COOH groups with inferior conductivity. The oxidized AC electrodes could substantially improve the specific capacitance (534 vs. 150.3 F g−1 at 1 A g−1) without sacrifice of rate performance (retained 418 F g−1 at 20 A g−1), accompanying excellent cycling stability of 94 % of initial capacitance after 10000 cycles. Such finding would provide some reference for tailoring oxygen species to fabricate advanced carbon‐based supercapacitor electrodes.

“We Are Here!” Oxygen Functional Groups in Carbons for Electrochemical Applications

“…This might improve the performance during the cycling process. 23 However, it is worth remembering that the presence of OFGs has also been reported to have negative effects. The most pronounced is the increased internal resistance of carbon.…”

“…The formation of the aforementioned groups suppressed the formation of −COOH with inferior conductivity. More importantly, the formed OFGs were very stable in acidic media upon 10,000 cycles …”

“…OFGs can also be introduced in situ during the cycling process in aqueous electrolyte especially when broad potential windows are applied. This might improve the performance during the cycling process . However, it is worth remembering that the presence of OFGs has also been reported to have negative effects.…”

Quinone-functionalised carbons as new materials for electrochemical carbon dioxide capture

“…have not yet been implemented in carbon capture technology. 32 In this work we develop quinone-functionalised porous carbon materials for electrochemically driven carbon dioxide capture. We demonstrate that the incorporation of quinones increases the energy storage capacity of the carbon electrodes, while at the same time introducing electrochemically mediated carbon dioxide capture.…”

Fluorinated Ether‐Based Electrolyte for Supercapacitors with Increased Working Voltage and Suppressed Self‐discharge

“…Supercapacitors as energy storage devices have attracted great attention due to their high power density and long cycle life [1–20] . In addition to improving the energy density of supercapacitors, reducing the self‐discharge is also an imperative research task for practical applications of supercapacitors [21–34] .…”