Shahed University

Asymmetric supercapacitors: An alternative to activated carbon negative electrodes based on earth abundant elements

Mohammad S. Rahmanifar | Maryam Hemmati | Abolhassan Noori | Maher F. El-Kady | Mir F. Mousavi | Richard B. Kaner
URL :   http://research.shahed.ac.ir/WSR/WebPages/Report/PaperView.aspx?PaperID=105948
Date :  2019/01/05
Publish in :    Materials Today Energy
DOI :  https://doi.org/10.1016/j.mtener.2018.12.006
Link :  http://dx.doi.org/10.1016/j.mtener.2018.12.006
Keywords :supercapacitors, alternative, electrodes, elements

Abstract :
High power performance with the ability to be charged in a matter of seconds have made supercapacitors the technology of choice for cutting-edge applications. However, improving the energy content of supercapacitors is necessary to contribute to the technological advancement of energy storage devices. Herein, we report the synthesis of two transition metal spinel oxide-reduced graphene oxide (rGO) nanocomposites; namely CuCo2O4-rGO and CoFe2O4-rGO. The CuCo2O4-rGO nanocomposite as a positive electrode exhibits an extremely high specific capacitance of 2064.0 F g1 at 2 A g1, whereas the CoFe2O4-rGO nanocomposite as a negative electrode shows a specific capacitance of 261.0 F g1 at 2 A g1. The asymmetric CoFe2O4-rGO//CuCo2O4-rGO device exhibits an ultrahigh specific energy of 77.2 Wh kg1 at 953.0 W kg1, maintains 8.3 Wh kg1 under the outstanding specific power of 21.0 kW kg1, and displays excellent cycling stability (96 capacitance retention after 5000 cycles). We also fabricated an asymmetric AC//CuCo2O4-rGO device (AC ΒΌ activated carbon) as a control, and realized that the CoFe2O4-rGO nanocomposite not only outperforms AC in terms of specific energy, but also contributes to a higher specific power. The results indicate that these nanocomposites are promising materials for the fabrication of high performance supercapacitors.