AUTHOR=Malaie Keyvan , Ganjali Mohammad Reza , Soavi Francesca 

TITLE=Toward Low-Cost and Sustainable Supercapacitor Electrode Processing: Simultaneous Carbon Grafting and Coating of Mixed-Valence Metal Oxides by Fast Annealing

JOURNAL=Frontiers in Chemistry

VOLUME=7

YEAR=2019

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2019.00025

DOI=10.3389/fchem.2019.00025

ISSN=2296-2646

ABSTRACT=<p>There is a rapid market growth for supercapacitors and batteries based on new materials and production strategies that minimize their cost, end-of-life environmental impact, and waste management. Herein, mixed-valence iron oxide (FeO<sub>x</sub>) and manganese oxide (Mn<sub>3</sub>O<sub>4</sub>) and FeO<sub>x</sub>-carbon black (FeO<sub>x</sub>-CB) electrodes with excellent pseudocapacitive behavior in 1 M Na<sub>2</sub>SO<sub>4</sub> are produced by a one-step thermal annealing. Due to the <italic>in situ</italic> grafted carbon black, the FeO<sub>x</sub>-CB shows a high pseudocapacitance of 408 mF cm<sup>−2</sup> (or 128 F g<sup>−1</sup>), and Mn<sub>3</sub>O<sub>4</sub> after activation shows high pseudocapacitance of 480 mF cm<sup>−2</sup> (192 F g<sup>−1</sup>). The asymmetric supercapacitor based on FeO<sub>x</sub>-CB and activated-Mn<sub>3</sub>O<sub>4</sub> shows a capacitance of 260 mF cm<sup>−2</sup> at 100 mHz and a cycling stability of 97.4% over 800 cycles. Furthermore, due to its facile redox reactions, the supercapacitor can be voltammetrically cycled up to a high rate of 2,000 mV s<sup>−1</sup> without a significant distortion of the voltammograms. Overall, our data indicate the feasibility of developing high-performance supercapacitors based on mixed-valence iron and manganese oxide electrodes in a single step.</p>