Study of MnO2-Graphene Oxide nanocomposites for supercapacitor applications

MRS Advances ◽  
2019 ◽  
Vol 4 (13) ◽  
pp. 777-782 ◽  
Author(s):  
Rahul Singhal ◽  
Justin Fagnoni ◽  
David Thorne ◽  
Peter K. LeMaire ◽  
Xavier Martinez ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Electrochemical Characterizations ◽  
Average Diameter ◽  
Deionized Water ◽  
Electrochemical Performances ◽  
X Ray Diffraction ◽  
X Ray ◽  
Supercapacitor Applications ◽  
A Current ◽  
Charge Discharge

ABSTRACTGraphene oxide (GO)/MnO2 nanocomposites were synthesized by adding KMnO4 in a solution of water and ethanol (3:1), containing 10 mg of GO. Brown precipitates were obtained after a continuous stirring for 1 hr. The precipitates were then washed with deionized water (DI) water and dried to obtain the MnO2-GO nanocomposites. Pure MnO2 was also synthesized using the same method without GO for the comparison. X-ray diffraction pattern confirm δ-MnO2 type of MnO2 with birnessite type MnO2 structure. The TEM images show the average diameter of MnO2 nanorods as 15 nm. Electrochemical characterizations were carried out in an aqueous solution of 3M KOH. Charge-discharge studies were carried out between 1A/g to 20 A/g current range. The MnO2-GO nanocomposites showed improved electrochemical performances. The capacitance of MnO2 and MnO2-GO electrodes was found to be as 300 F/g, and 350 F/g, respectively at a current of 0.5 A/g.

Preparation of Co-Ni Mixed Oxide/Graphene Composite and its Electrochemical Performances as Supercapacitor Material

2017 ◽  
Vol 727 ◽  
pp. 775-780 ◽  
Author(s):  
Yun Long Zhou ◽  
Chen Hao Zhao ◽  
Zhi Biao Hu ◽  
Xue Yan Huang ◽  
Kai Yu Liu ◽  
...  
Keyword(s):  
Cyclic Voltammetry ◽  
Mixed Oxides ◽  
Electrochemical Performances ◽  
X Ray Diffraction ◽  
Galvanostatic Charge ◽  
X Ray ◽  
Graphene Composite ◽  
A Current ◽  
Charge Discharge ◽  
Discharge Test

The Co-Ni mixed oxides/graphene composite has been prepared using the solution based oxidation route. The structures of bare Co-Ni mixed oxides and Co-Ni mixed oxides/graphene composite is clearly studied by X-ray diffraction. The electrochemical properties of Co-Ni mixed oxides/graphene composite are investigated by Cyclic Voltammetry (CV) and galvanostatic charge discharge test. The result shows that, the NiO phase has not been detected in the composite, and the graphene composite delivers a discharge capacity of 353.6 F/g at a current density of 0.32 A g-1.

Preparation and Electrochemical Performance of Mn3O4/GR Composites Electrode Material in Supercapacitors

2019 ◽  
Vol 807 ◽  
pp. 50-56
Author(s):  
Yun Long Zhou ◽  
Zhi Biao Hu ◽  
Li Mei Wu ◽  
Jiao Hao Wu
Keyword(s):  
Room Temperature ◽  
Raw Materials ◽  
Precipitation Method ◽  
Electrochemical Performances ◽  
Manganese Sulfate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Co Precipitation ◽  
A Current ◽  
Discharge Test

Using hydrated manganese sulfate and general type graphene (GR) as raw materials, Mn3O4/GR composite has been successfully prepared by the liquid phase chemical co-precipitation method at room temperature. X-ray diffraction (XRD) was used to investigate the phase structure of Mn3O4powder and Mn3O4/GR composite; The electrochemical performances of the samples were elucidated by cyclic voltammetry and galvanostatic charge-discharge test in 0.5 mol/L Na2SO4electrolyte. The results show that the Mn3O4/GR composite possesses graphene phase and good reversibility; the composite also displays a specific capacitance of 318.8 F/g at a current density of 1 A/g.

Graphene Oxide/Fe3O4 Composites Prepared via In Situ Precipitation

2014 ◽  
Vol 904 ◽  
pp. 150-154
Author(s):  
Zhe Wei Yang ◽  
Xin Fan ◽  
Li Ang Guo ◽  
Wei Ting Wei
Keyword(s):  
Graphene Oxide ◽  
Specific Capacitance ◽  
Precipitation Method ◽  
Electrochemical Performances ◽  
Composite Electrodes ◽  
X Ray Diffraction ◽  
Bonding Force ◽  
X Ray

The graphene oxide/Fe3O4 composites were prepared by in situ precipitation method in this article. The microstructure and surface morphology of composites were characterized by Fourier transform infrared spectrum, X-ray diffraction and scanning electron microscopy, respectively. Cyclic voltammetry was employed for the determination of specific capacitance and other electrochemical performances. It was shown that there was the chemical bonding force between GO and Fe3O4 particles. And the surfaces of GO were wrapped by the Fe3O4 particles precipitated on the surfaces of GO sheets and no impurities were detected. Furthermore, the specific capacitance of GO/Fe3O4 composite electrodes decreased as Fe3O4 particles reduced and the redox peaks became weaker owing to the addition of nonconductive Fe3O4 particles.

scholarly journals Silicon Carbide-Derived Carbon Prepared by Fused Salt Electrolysis and Electrochemical Performance

2016 ◽  
Vol 2016 ◽  
pp. 1-6
Author(s):  
Shuyuan Wang ◽  
Guangjie Shao
Keyword(s):  
Electrochemical Performances ◽  
Constant Voltage ◽  
X Ray Diffraction ◽  
Galvanostatic Charge ◽  
X Ray ◽  
Transmission Electron ◽  
Different Temperatures ◽  
Carbide Derived Carbon ◽  
Degree Of Order ◽  
A Current

A number of carbide-derived carbon (CDC) samples were successfully synthesized by the electrolysis of SiC powder in molten CaCl2. The electrolysis was conducted at different temperatures (850, 900, and 950°C) for 48 h in argon at an applied constant voltage of 3.1 V. The structure of the resulting carbon is characterized by X-ray diffraction, Raman spectroscopy, and transmission electron microscope techniques. Cyclic voltammetry and galvanostatic charge/discharge measurements are applied to investigate electrochemical performances of the SiC-CDC material. It can be seen that the degree of order of the SiC-CDC increases monotonically along with elevation of reaction temperature, while the highest specific surface area 1137.74 m2/g together with a specific capacitance of 161.27 F/g at a current density 300 mA/g was achieved from sample synthesized at 900°C.

Low Surface Energy and pH Effect on SnO2 Nanoparticles Formation for Supercapacitor Applications

2019 ◽  
Vol 19 (6) ◽  
pp. 3429-3436
Author(s):  
B Saravanakumar ◽  
G Ravi ◽  
V Ganesh ◽  
S Ravichandran ◽  
A Sakunthala ◽  
...  
Keyword(s):  
Cetyltrimethylammonium Bromide ◽  
Sno2 Nanoparticles ◽  
Ph Effect ◽  
High Specific Capacitance ◽  
X Ray Diffraction ◽  
Experimental Conditions ◽  
X Ray ◽  
Low Surface Energy ◽  
Supercapacitor Applications ◽  
A Current

The SnO2 nanoparticles formation by hydrothermal method at different experimental conditions such as temperature, pH, reaction time, and capping agent (cetyltrimethylammonium bromide), was studied. X-ray diffraction results confirmed regular rutile crystal structure of SnO2. The characteristic Raman peak observed at 635 cm−1 corresponded to A1g modes of Sn–O vibrations. The study of optical property using photoluminescence confirmed the emissive spectra of SnO2. The infrared peak observed at 618 cm−1 corresponded to Eu modes of Sn–O vibrations of TO phonon because of E⊥ to c-axis. Scanning electron microscope images clearly revealed the formation of complete SnO2 nanoparticles. The unique SnO2 nanoparticles stacked together to form microspheres at pH-5 showed high specific capacitance of 274.8 F/g at a current density of 0.5 A/g. The observed results confirmed the feasibility of SnO2 nanoparticles being used as appropriate positive electrode candidate for supercapacitor applications.

Ag Doped Co3O4 Nanowire Arrays as an Electrode Material for Electrochemical Capacitors

2012 ◽  
Vol 268-270 ◽  
pp. 157-163 ◽  
Author(s):  
Yang Xu ◽  
Ji Chun Huang ◽  
Lin Cheng ◽  
Dian Xue Cao ◽  
Gui Ling Wang
Keyword(s):  
Electrochemical Impedance ◽  
Nickel Foam ◽  
Nanowire Arrays ◽  
X Ray Diffraction ◽  
X Ray ◽  
Growth Method ◽  
Template Free ◽  
A Current ◽  
Charge Discharge ◽  
Discharge Test

Co3O4 nanowire arrays freely standing on nickel foam are prepared via a template-free growth method，and it is doped by Ag via electrodeposition method (denoted as NWA-Ag/Co3O4，NWA represents Nanowire Arrays). The morphology of NWA-Ag/Co3O4 is examined by scanning electron microscopy. The phase structure of the NWA-Ag/Co3O4 electrode is characterized by X-ray diffraction spectroscopy. The supercapacitance behavior of the NWA-Ag/Co3O4 electrodes is investigated by cyclic voltammetry, galvanostatic charge/discharge test and electrochemical impedance spectroscopy. The results show that the nanowire arrays densely cover the nickel foam substrate and have diameters around 250 nm. The NWA-Ag/Co3O4 electrodes exhibit a specific capacitance of 1009 F g−1 at a current density of 5 mA cm-2 in 6.0 mol dm-3 KOH electrolyte. The capacitance loss is less than 6.5% after 500 charge/discharge cycles at 10 mA cm-2 and with columbic efficiency higher than 97.5%.

One-pot hydrothermal synthesis of polyaniline nanofibers/reduced graphene oxide nanocomposites and their supercapacitive properties

2019 ◽  
Vol 31 (9-10) ◽  
pp. 1238-1247 ◽  
Author(s):  
Shanxin Xiong ◽  
Yuancheng Wang ◽  
Jia Chu ◽  
Xiaoqin Wang ◽  
Runlan Zhang ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Specific Capacitance ◽  
Current Density ◽  
Electrochemical Performances ◽  
One Pot ◽  
Raman Analysis ◽  
Polyaniline Nanofibers ◽  
Reduced Graphene ◽  
A Current ◽  
Charge Discharge

In this article, polyaniline nanofibers/reduced graphene oxide (PANI-NFs/rGO) nanocomposites were prepared by a one-pot hydrothermal method. Under the condition of high temperature and high pressure, graphene oxide (GO) was reduced to rGO and aniline was in-situ polymerized to form PANI-NFs using ammonium persulfate as oxidant. The morphologies and structures of PANI-NFs/rGO nanocomposites were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR), and Raman analysis. The results show that PANI-NFs uniformly grow on the surfaces of rGO sheets, which can act as spacers to prevent the aggregation of rGO. Combining with FTIR and Raman analysis, it can be concluded that PANI-NFs/rGO nanocomposites are successfully prepared. The electrochemical performances of PANI-NFs/rGO nanocomposites were tested by cyclic voltammetry and galvanostatic charge–discharge. The PANI-NFs/rGO nanocomposites exhibit superior electrochemical performances compared to the PANI-NFs. With 10 wt% of GO loaded, the PANI-NFs/rGO nanocomposite exhibits highest specific capacitance of 942 F g−1 at a current density of 1 A g−1. The PANI-NFs/rGO nanocomposites also demonstrate good rate capacity and high cycling stability under the high discharging current density (10 A g−1), the specific capacitance can still reach to 680 F g−1. After 1000 charge–discharge cycling at a current density of 5 A g−1, 78% of specific capacitance can be retained. The enhanced capacitive performances can be attributed to the facile electron conduction pathway brought by the even distribution of highly conductive rGO nanosheets.

Preparation and Electrochemical Performances of Li4Ti5O12 as Anode Material

2012 ◽  
Vol 512-515 ◽  
pp. 1976-1979 ◽  
Author(s):  
Fang Gu
Keyword(s):  
Solution Method ◽  
Reversible Capacity ◽  
Electrochemical Performances ◽  
Rate Performance ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structure And Morphology ◽  
Initial Charge ◽  
Charge Discharge ◽  
Scanning Electron

Spinel Li4Ti5O12 was prepared by a solution method. The structure and morphology of the samples were characterized by X-ray diffraction, scanning electron microscopy. The electrochemical performance was investigated by initial charge-discharge at different rate. The results revealed that the crystallinity of Li4Ti5O12 was well, the Li4Ti5O12 prepared by solution method had a relatively smaller particle size and homogeneous morphology. It delivered a discharge capacity 178.59 mAh•g−1 for the Li4Ti5O12 at the 0.2C discharge to 1V. The reversible capacity 141.98mAh•g−1 could be achieved at the 5C . Li4Ti5O12 prepared by a solution method showed good rate performance.

Synthesis of LiFePO4/C by Carbon Thermal Reduction Method and its Electrochemical Properties

2011 ◽  
Vol 335-336 ◽  
pp. 1364-1367 ◽  
Author(s):  
Chao Chen ◽  
Yun Zhang ◽  
Fu Wang ◽  
Ji Zhou Zou
Keyword(s):  
Reduction Method ◽  
Carbon Sources ◽  
Thermal Reduction ◽  
Electrochemical Performances ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structure Morphology ◽  
Good Cycling Stability ◽  
Charge Discharge ◽  
Discharge Test

LiFePO4/C were successfully synthesized by carbon thermal reduction method at sintering temperature of 650 °C for 12h, using Li2CO3, FePO4 and three organic carbon sources (citric acid, glucose and ascorbic acid) as starting materials. The crystal structure, morphology and electrochemical performances were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM) and Charge/Discharge Test. The results showed that the sample using glucose as carbon source was shuttle type porous particles with bore diameter from 50 to 100 nm, charge/discharge test showed that the sample had not only high initial discharge capacity of 155.1mAh/g at 0.1C (17mA/g), and 144.8 mAh/g at 1C, but also excellent rate performance. Moreover, the capacities lose which was only 0.97% after 10 cycling number at 1C indicate its good cycling stability.

Al Doped LiMn2O4 Prepared by a Solution Combustion Synthesis Using Acetate Salts as Raw Materials and Acetic Acid as Fuel

2011 ◽  
Vol 142 ◽  
pp. 209-212
Author(s):  
Gui Yang Liu ◽  
Jun Ming Guo ◽  
Li Li Zhang ◽  
Bao Sen Wang ◽  
Ying He
Keyword(s):  
Acetic Acid ◽  
Combustion Synthesis ◽  
Raw Materials ◽  
Synthesis Method ◽  
Solution Combustion Synthesis ◽  
Electrochemical Performances ◽  
X Ray Diffraction ◽  
Solution Combustion ◽  
X Ray ◽  
Charge Discharge

To improve the cyclability of spinel LiMn2O4, Al3+doped LiAlxMn2−xO4(x=0, 0.01, 0.05 and 0.10) materials are prepared using a solution combustion synthesis method using acetic salts as raw materials and acetic acid as fuel. Their phase structures are characterized by X-ray diffraction (XRD). Electrochemical performances of the materials are investigated by galvanostatic charge/discharge methods. XRD results reveal that the purity of the samples increases with increasing Al3+content. Electrochemical experiments demonstrate that the charge/discharge cyclability of the LiAlxMn2-xO4increases with increasing Al3+content. Compared with the pristine LiMn2O4, the Al-doped LiAlxMn1−xO4show the obviously improved cyclability, especially for the sample LiAl0.1Mn1.9O4.

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