title: High-Performance Asymmetric Supercapacitors of MnCo2O4Nanofibers and N-Doped Reduced Graphene Oxide Aerogel.
abstract: The working potential of symmetric supercapacitors is not so wide because one type of material used for the supercapacitor electrodes prefers either positive or negative charge to both charges. To address this problem, a novel asymmetrical supercapacitor (ASC) of battery-type MnCo2O4nanofibers (NFs)//N-doped reduced graphene oxide aerogel (N-rGOAE) was fabricated in this work. The MnCo2O4NFs at the positive electrode store the negative charges, i.e., solvated OH-, while the N-rGOAEat the negative electrode stores the positive charges, i.e., solvated K+. An as-fabricated aqueous-based MnCo2O4//N-rGOAEASC device can provide a wide operating potential of 1.8 V and high energy density and power density at 54 W h kg-1and 9851 W kg-1, respectively, with 85.2% capacity retention over 3000 cycles. To understand the charge storage reaction mechanism of the MnCo2O4, the synchrotron-based X-ray absorption spectroscopy (XAS) technique was also used to determine the oxidation states of Co and Mn at the MnCo2O4electrode after being electrochemically tested. The oxidation number of Co is oxidized from +2.76 to +2.85 after charging and reduced back to +2.75 after discharging. On the other hand, the oxidation state of Mn is reduced from +3.62 to +3.44 after charging and oxidized to +3.58 after discharging. Understanding in the oxidation states of Co and Mn at the MnCo2O4electrode here leads to the awareness of the uncertain charge storage mechanism of the spinel-type oxide materials. High-performance ASC here in this work may be practically used in high-power applications.
authors.affiliation: Department of Chemical and Biomolecular Engineering, School of Energy Science and Engineering, Vidyasirimedhi Institute of Science and Technology , Rayong 21210, Thailand.|Department of Chemical Engineering, Center for Advanced Studies in Nanotechnology for Chemical, Food and Agricultural Industries, and NANOTEC-KU-Centre of Excellence on Nanoscale Materials Design for Green Nanotechnology, Kasetsart University , Bangkok 10900, Thailand.
authors.forename: Tanut
authors.initials: T
authors.lastname: Pettong
authors.affiliation: Department of Chemical and Biomolecular Engineering, School of Energy Science and Engineering, Vidyasirimedhi Institute of Science and Technology , Rayong 21210, Thailand.|Department of Chemical Engineering, Center for Advanced Studies in Nanotechnology for Chemical, Food and Agricultural Industries, and NANOTEC-KU-Centre of Excellence on Nanoscale Materials Design for Green Nanotechnology, Kasetsart University , Bangkok 10900, Thailand.
authors.forename: Pawin
authors.initials: P
authors.lastname: Iamprasertkun
authors.affiliation: Department of Chemical and Biomolecular Engineering, School of Energy Science and Engineering, Vidyasirimedhi Institute of Science and Technology , Rayong 21210, Thailand.
authors.forename: Atiweena
authors.initials: A
authors.lastname: Krittayavathananon
authors.affiliation: Department of Chemical and Biomolecular Engineering, School of Energy Science and Engineering, Vidyasirimedhi Institute of Science and Technology , Rayong 21210, Thailand.|Department of Chemical Engineering, Center for Advanced Studies in Nanotechnology for Chemical, Food and Agricultural Industries, and NANOTEC-KU-Centre of Excellence on Nanoscale Materials Design for Green Nanotechnology, Kasetsart University , Bangkok 10900, Thailand.
authors.forename: Phansiri
authors.initials: P
authors.lastname: Sukha
authors.affiliation: Department of Chemical and Biomolecular Engineering, School of Energy Science and Engineering, Vidyasirimedhi Institute of Science and Technology , Rayong 21210, Thailand.|Department of Chemical Engineering, Center for Advanced Studies in Nanotechnology for Chemical, Food and Agricultural Industries, and NANOTEC-KU-Centre of Excellence on Nanoscale Materials Design for Green Nanotechnology, Kasetsart University , Bangkok 10900, Thailand.
authors.forename: Pichamon
authors.initials: P
authors.lastname: Sirisinudomkit
authors.affiliation: Department of Chemical Engineering, Center for Advanced Studies in Nanotechnology for Chemical, Food and Agricultural Industries, and NANOTEC-KU-Centre of Excellence on Nanoscale Materials Design for Green Nanotechnology, Kasetsart University , Bangkok 10900, Thailand.
authors.forename: Anusorn
authors.initials: A
authors.lastname: Seubsai
authors.affiliation: Department of Chemical Engineering, Center for Advanced Studies in Nanotechnology for Chemical, Food and Agricultural Industries, and NANOTEC-KU-Centre of Excellence on Nanoscale Materials Design for Green Nanotechnology, Kasetsart University , Bangkok 10900, Thailand.
authors.forename: Metta
authors.initials: M
authors.lastname: Chareonpanich
authors.affiliation: Department of Chemical Engineering, Center for Advanced Studies in Nanotechnology for Chemical, Food and Agricultural Industries, and NANOTEC-KU-Centre of Excellence on Nanoscale Materials Design for Green Nanotechnology, Kasetsart University , Bangkok 10900, Thailand.
authors.forename: Paisan
authors.initials: P
authors.lastname: Kongkachuichay
authors.affiliation: Department of Materials Science and Engineering, School of Molecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology , Rayong 21210, Thailand.
authors.forename: Jumras
authors.initials: J
authors.lastname: Limtrakul
authors.affiliation: Department of Chemical and Biomolecular Engineering, School of Energy Science and Engineering, Vidyasirimedhi Institute of Science and Technology , Rayong 21210, Thailand.
authors.forename: Montree
authors.initials: M
authors.lastname: Sawangphruk
keywords: MnCo2O4 nanofibers; N-doped reduced graphene oxide aerogel; X-ray absorption spectroscopy; asymmetrical supercapacitor; charge storage mechanism