Development of magnesium cobalt oxide and its composite with reduced graphene oxide for asymmetric supercapacitor applications

This thesis aims to evaluate the suitability of magnesium cobalt oxide (MgCo2O4) as a pseudocapacitor electrode in asymmetric supercapacitors (ASCs) with improved energy density (ED) and power density (PD). MgCo2O4 belongs to ternary metal cobaltites having desirable electrochemical properties for e...

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Main Author:	Krishnan, Syam G.
Format:	Thesis
Language:	English English English
Published:	2017
Subjects:	Q Science (General)
Online Access:	http://umpir.ump.edu.my/id/eprint/18205/ http://umpir.ump.edu.my/id/eprint/18205/ http://umpir.ump.edu.my/id/eprint/18205/1/Development%20of%20magnesium%20cobalt%20oxide%20and%20its%20composite%20with%20reduced%20graphene%20oxide%20for%20asymmetric%20supercapacitor%20applications-Table%20of%20contents.pdf http://umpir.ump.edu.my/id/eprint/18205/2/Development%20of%20magnesium%20cobalt%20oxide%20and%20its%20composite%20with%20reduced%20graphene%20oxide%20for%20asymmetric%20supercapacitor%20applications-Abstract.pdf http://umpir.ump.edu.my/id/eprint/18205/13/Development%20of%20magnesium%20cobalt%20oxide%20and%20its%20composite%20with%20reduced%20graphene%20oxide%20for%20asymmetric%20supercapacitor%20applications-References.pdf

id	ump-18205
recordtype	eprints
spelling	ump-182052017-07-18T08:01:59Z http://umpir.ump.edu.my/id/eprint/18205/ Development of magnesium cobalt oxide and its composite with reduced graphene oxide for asymmetric supercapacitor applications Krishnan, Syam G. Q Science (General) This thesis aims to evaluate the suitability of magnesium cobalt oxide (MgCo2O4) as a pseudocapacitor electrode in asymmetric supercapacitors (ASCs) with improved energy density (ED) and power density (PD). MgCo2O4 belongs to ternary metal cobaltites having desirable electrochemical properties for energy storage devices such as batteries and supercapacitors. In pseudocapacitors, charges are stored at the surface of an electrode by fast faradic reaction and offer improved ED and PD compared to conventional supercapacitors in which charge storage is limited by accumulation at the electrode– electrolyte interface. In this research, three typical morphologies of MgCo2O4 are synthesized using molten salt method (MSM) and hydrothermal method (HT). These synthetic processes offer controllability of properties of the materials thereby produced and scalability of materials production. A high performing ternary metal cobaltite, viz. manganese cobalt oxide (MnCo2O4) is used as a control material owing to its higher theoretical capacitance (~3620 Fg-1) compared to that of MgCo2O4 (~3120 Fg-1) in all the above synthesis. In addition to the pure compounds, their graphene modified analogues are also synthesized. The materials are characterized using thermogravimetric analysis (TGA), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), and gas surface adsorption techniques. Electrochemical properties of MgCo2O4 and MnCo2O4 are evaluated using cyclic voltammetry (CV), galvanostatic charge-discharge (CD) and electrochemical impedance spectroscopy (EIS) in a three-electrode system using 3 M LiOH as electrolyte. A detailed investigation of the pseudocapacitive performance of the various electrode including the graphene modified ones on the specific capacitance (CS) has been undertaken in threeelectrode configuration. These characterizations revealed the superiority of MgCo2O4 over MnCo2O4 electrodes. Furthermore, performance of graphene modified MgCo2O4 and MnCo2O4 showed superior capacitance of ~570 and ~440 Fg-1, with capacitance retention of 104 and 102%, respectively at the end of 3000 cycles. ASCs are fabricated using graphene modified MgCo2O4 (HS-G-MgCo2O4) and MnCo2O4 (HS-G-MnCo2O4) as anodes and activated carbon (AC) as cathode. A trial and error method is adopted to determine suitable mass loading of the materials in respective electrodes for high ED and PD. Highest ED and PD are obtained for 1:1 wt.% mass loading in anode and cathode. The HS-G-MgCo2O4/AC delivered a maximum ED of ~31.05 Whkg-1 at PD of 1.8 kWkg-1, which is one of the best performances reported for ternary metal cobaltite based ASCs. This research, therefore, identifies a promising pseudocapacitor electrode material for commercial deployment. 2017-03 Thesis NonPeerReviewed application/pdf en http://umpir.ump.edu.my/id/eprint/18205/1/Development%20of%20magnesium%20cobalt%20oxide%20and%20its%20composite%20with%20reduced%20graphene%20oxide%20for%20asymmetric%20supercapacitor%20applications-Table%20of%20contents.pdf application/pdf en http://umpir.ump.edu.my/id/eprint/18205/2/Development%20of%20magnesium%20cobalt%20oxide%20and%20its%20composite%20with%20reduced%20graphene%20oxide%20for%20asymmetric%20supercapacitor%20applications-Abstract.pdf application/pdf en http://umpir.ump.edu.my/id/eprint/18205/13/Development%20of%20magnesium%20cobalt%20oxide%20and%20its%20composite%20with%20reduced%20graphene%20oxide%20for%20asymmetric%20supercapacitor%20applications-References.pdf Krishnan, Syam G. (2017) Development of magnesium cobalt oxide and its composite with reduced graphene oxide for asymmetric supercapacitor applications. PhD thesis, Universiti Malaysia Pahang. http://iportal.ump.edu.my/lib/item?id=chamo:99857&theme=UMP2
repository_type	Digital Repository
institution_category	Local University
institution	Universiti Malaysia Pahang
building	UMP Institutional Repository
collection	Online Access
language	English English English
topic	Q Science (General)
spellingShingle	Q Science (General) Krishnan, Syam G. Development of magnesium cobalt oxide and its composite with reduced graphene oxide for asymmetric supercapacitor applications
description	This thesis aims to evaluate the suitability of magnesium cobalt oxide (MgCo2O4) as a pseudocapacitor electrode in asymmetric supercapacitors (ASCs) with improved energy density (ED) and power density (PD). MgCo2O4 belongs to ternary metal cobaltites having desirable electrochemical properties for energy storage devices such as batteries and supercapacitors. In pseudocapacitors, charges are stored at the surface of an electrode by fast faradic reaction and offer improved ED and PD compared to conventional supercapacitors in which charge storage is limited by accumulation at the electrode– electrolyte interface. In this research, three typical morphologies of MgCo2O4 are synthesized using molten salt method (MSM) and hydrothermal method (HT). These synthetic processes offer controllability of properties of the materials thereby produced and scalability of materials production. A high performing ternary metal cobaltite, viz. manganese cobalt oxide (MnCo2O4) is used as a control material owing to its higher theoretical capacitance (~3620 Fg-1) compared to that of MgCo2O4 (~3120 Fg-1) in all the above synthesis. In addition to the pure compounds, their graphene modified analogues are also synthesized. The materials are characterized using thermogravimetric analysis (TGA), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), and gas surface adsorption techniques. Electrochemical properties of MgCo2O4 and MnCo2O4 are evaluated using cyclic voltammetry (CV), galvanostatic charge-discharge (CD) and electrochemical impedance spectroscopy (EIS) in a three-electrode system using 3 M LiOH as electrolyte. A detailed investigation of the pseudocapacitive performance of the various electrode including the graphene modified ones on the specific capacitance (CS) has been undertaken in threeelectrode configuration. These characterizations revealed the superiority of MgCo2O4 over MnCo2O4 electrodes. Furthermore, performance of graphene modified MgCo2O4 and MnCo2O4 showed superior capacitance of ~570 and ~440 Fg-1, with capacitance retention of 104 and 102%, respectively at the end of 3000 cycles. ASCs are fabricated using graphene modified MgCo2O4 (HS-G-MgCo2O4) and MnCo2O4 (HS-G-MnCo2O4) as anodes and activated carbon (AC) as cathode. A trial and error method is adopted to determine suitable mass loading of the materials in respective electrodes for high ED and PD. Highest ED and PD are obtained for 1:1 wt.% mass loading in anode and cathode. The HS-G-MgCo2O4/AC delivered a maximum ED of ~31.05 Whkg-1 at PD of 1.8 kWkg-1, which is one of the best performances reported for ternary metal cobaltite based ASCs. This research, therefore, identifies a promising pseudocapacitor electrode material for commercial deployment.
format	Thesis
author	Krishnan, Syam G.
author_facet	Krishnan, Syam G.
author_sort	Krishnan, Syam G.
title	Development of magnesium cobalt oxide and its composite with reduced graphene oxide for asymmetric supercapacitor applications
title_short	Development of magnesium cobalt oxide and its composite with reduced graphene oxide for asymmetric supercapacitor applications
title_full	Development of magnesium cobalt oxide and its composite with reduced graphene oxide for asymmetric supercapacitor applications
title_fullStr	Development of magnesium cobalt oxide and its composite with reduced graphene oxide for asymmetric supercapacitor applications
title_full_unstemmed	Development of magnesium cobalt oxide and its composite with reduced graphene oxide for asymmetric supercapacitor applications
title_sort	development of magnesium cobalt oxide and its composite with reduced graphene oxide for asymmetric supercapacitor applications
publishDate	2017
url	http://umpir.ump.edu.my/id/eprint/18205/ http://umpir.ump.edu.my/id/eprint/18205/ http://umpir.ump.edu.my/id/eprint/18205/1/Development%20of%20magnesium%20cobalt%20oxide%20and%20its%20composite%20with%20reduced%20graphene%20oxide%20for%20asymmetric%20supercapacitor%20applications-Table%20of%20contents.pdf http://umpir.ump.edu.my/id/eprint/18205/2/Development%20of%20magnesium%20cobalt%20oxide%20and%20its%20composite%20with%20reduced%20graphene%20oxide%20for%20asymmetric%20supercapacitor%20applications-Abstract.pdf http://umpir.ump.edu.my/id/eprint/18205/13/Development%20of%20magnesium%20cobalt%20oxide%20and%20its%20composite%20with%20reduced%20graphene%20oxide%20for%20asymmetric%20supercapacitor%20applications-References.pdf
first_indexed	2023-09-18T22:25:39Z
last_indexed	2023-09-18T22:25:39Z
_version_	1777415948692619264

Development of magnesium cobalt oxide and its composite with reduced graphene oxide for asymmetric supercapacitor applications

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