Salting-out aided dispersive extraction of Mn3O4 nanoparticles and carbon nanotubes for application in supercapacitors

2021

Materials

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MXenes, such as Ti3C2Tx, are promising materials for electrodes of supercapacitors (SCs). Colloidal techniques have potential for the fabrication of advanced Ti3C2Tx composites with high areal capacitance (CS). This paper reports the fabrication of Ti3C2TX-Fe3O4-multiwalled carbon nanotube (CNT) electrodes, which show CS of 5.52 F cm−2 in the negative potential range in 0.5 M Na2SO4 electrolyte. Good capacitive performance is achieved at a mass loading of 35 mg cm−2 due to the use of Celestine blue (CB) as a co-dispersant for individual materials. The mechanisms of CB adsorption on Ti3C2TX, Fe3O4, and CNTs and their electrostatic co-dispersion are discussed. The comparison of the capacitive behavior of Ti3C2TX-Fe3O4-CNT electrodes with Ti3C2TX-CNT and Fe3O4-CNT electrodes for the same active mass, electrode thickness and CNT content reveals a synergistic effect of the individual capacitive materials, which is observed due to the use of CB. The high CS of Ti3C2TX-Fe3O4-CNT composites makes them promising materials for application in negative electrodes of asymmetric SC devices.

Section: Resultssupporting

confidence: 87%

Composite Fe3O4-MXene-Carbon Nanotube Electrodes for Supercapacitors Prepared Using the New Colloidal Method

Liang

2021

Materials

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“…Mn 3 O 4 nanoparticles were prepared by a modified chemical precipitation method [ 23 ] and mixed with MWCNT. In method 1, a solution of 330 mg of Mn(NO 3 ) 2 ·4H 2 O in 20 mL of DI water was prepared and then the pH of the solution was increased to pH = 10 with aqueous NaOH for the Mn 3 O 4 synthesis.…”

Section: Methodsmentioning

confidence: 99%

“…It was found that first charge-discharge cycles of Mn 3 O 4 electrodes showed low capacitance and activation cycling procedure was necessary in order to activate material and achieve high capacitance. Such activation procedures resulted in significant capacitance increase [ 20 , 22 , 23 , 24 ]. Several XPS studies revealed oxidation of Mn 2+ and Mn 3+ ions on the Mn 3 O 4 particle surface during cycling and linked this process to the increasing capacitance [ 20 , 21 , 22 , 25 ].…”

Section: Introductionmentioning

confidence: 99%

Colloidal Processing of Mn3O4-Carbon Nanotube Nanocomposite Electrodes for Supercapacitors

2022

Nanomaterials

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This investigation addresses the challenges in the development of efficient nanostructured Mn3O4 cathodes for supercapacitors. A high areal capacitance and the ability to avoid a time-consuming activation procedure for electrodes with high active mass loading of 40 mg cm−2 are reported. This facilitates practical applications of Mn3O4 based electrodes. The highest capacitance of 6.11 F cm−2 (153 F g−1) is obtained from cyclic voltammetry at a scan rate of 2 mV s−1 and 6.07 F cm−2 (151.9 F g−1) from the chronopotentiometry at a current density of 3 mA cm−2 in a potential window of 0.9 V in a neutral Na2SO4 electrolyte. The new approach is based on the application of rhamnolipids (RL) as a capping agent for the synthesis of Mn3O4 particles and a co-dispersant for Mn3O4 and carbon nanotubes, which are used as conductive additives. The size and shape of the Mn3O4 particles are influenced by RL. The enhanced performance of the electrodes is linked to the chemical structure and properties of RL molecules, which exert influence on Mn3O4 particle size and shape during synthesis, reduce agglomeration, facilitate RL adsorption on Mn3O4 and carbon nanotubes, and influence their co-dispersion and mixing at the nanometric scale.

“…Mn 3 O 4 nanoparticles were prepared by a modified chemical precipitation method [30] and mixed with MWCNTs. A solution of 0.33 g of Mn(NO 3 ) 2 •4H 2 O in DI water was prepared, and then the pH of the solution was increased to pH = 10 with aqueous NaOH for the Mn 3 O 4 synthesis.…”

Section: Synthesis Of Mn 3 O 4 and Electrode Fabricationmentioning

confidence: 99%

“…Previous investigations [6] have showed that the capacitance of Mn 3 O 4 is significantly lower than that of MnO 2 . However, a significant increase in the capacitance of Mn 3 O 4 was observed during cycling [30][31][32][33]. Numerous XPS studies revealed oxidation of Mn 2+ and Mn 3+ ions on the Mn 3 O 4 particle surface during cycling and linked this process to the capacitance increase [31,[33][34][35].…”

Section: Introductionmentioning

confidence: 99%

Facile Route for Fabrication of Ferrimagnetic Mn3O4 Spinel Material for Supercapacitors with Enhanced Capacitance

Nawwar

2022

Energies

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The purpose of this investigation was the development of a new colloidal route for the fabrication of Mn3O4 electrodes for supercapacitors with enhanced charge storage performance. Mn3O4-carbon nanotube electrodes were fabricated with record-high capacitances of 6.67 F cm−2 obtained from cyclic voltammetry tests at a scan rate of 2 mV s−1 and 7.55 F cm−2 obtained from the galvanostatic charge–discharge tests at a current density of 3 mA cm−2 in 0.5 M Na2SO4 electrolyte in a potential window of 0.9 V. The approach involves the use of murexide as a capping agent for the synthesis of Mn3O4 and a co-dispersant for Mn3O4 and carbon nanotubes. Good electrochemical performance of the electrode material was achieved at a high active mass loading of 40 mg cm−2 and was linked to a reduced agglomeration of Mn3O4 nanoparticles and efficient co-dispersion of Mn3O4 with carbon nanotubes. The mechanisms of murexide adsorption on Mn3O4 and carbon nanotube are discussed. With the proposed method, the time-consuming electrode activation procedure for Mn3O4 electrodes can be avoided. The approach developed in this investigation paves the way for the fabrication of advanced cathodes for asymmetric supercapacitors and multifunctional devices, combining capacitive, magnetic, and other functional properties.