Oxidation of manganese(II) and reduction of manganese dioxide in sulphuric acid

J Solid State Electrochem

et al. 2013

“…At Cathode: 2H++2e−→H2 (2) At the anode, the formation of MnO 2 does not take place in a single step; rather, Mn 3+ as an intermediate species is first formed [19,20] …”

Section: Results and Discussion Electrolysismentioning

confidence: 99%

Electrodeposition of manganese dioxide: effect of quaternary amines

J Solid State Electrochem

et al. 2013

“…Surfactant addition to the electrolytic bath causes formation of a froth which covers the solution interface and minimizes hydrogen evolution and the release of acid mist; this is thus an added advantage of the use of surfactant. The energy consumption also reduces to 1.353 kWh kg 35,36 When surfactants are present in solution, they may inhibit the formation of Mn 3+ intermediate species in solution by adsorbing at the substrate/electrolytic solution interface. Surfactant molecules may also block active growth sites, thereby allowing electrodeposition preferentially on crevices.…”

Section: Resultsmentioning

confidence: 99%

Dual Effect of Anionic Surfactants in the Electrodeposited MnO₂Trafficking Redox Ions for Energy Storage

et al. 2014

J. Electrochem. Soc.

The dual effect of in-situ addition of anionic surfactants, sodium octyl sulfate (SOS), sodium dodecyl sulfate (SDS) and sodium tetradecyl sulfate (STS) on the microstructure and electrochemical properties of electrolytic manganese dioxide (EMD) produced from waste low grade manganese residue is discussed. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), BET-surface area studies, thermogravimetry-differential thermal analysis (TG-DTA) and Fourier transform infrared spectroscopy (FTIR) were used to determine the structure and chemistry of the EMD. All EMD samples were found to contain predominantly γ-phase MnO 2 , which is electrochemically active for energy storage applications. FESEM images showed that needle, rod and flower shaped nano-particles with a porous surface and platy nano-particles were obtained in the case of EMD deposited with and without surfactant respectively. Thermal studies showed loss of structural water and formation of lower manganese oxides indicating high stability of the EMD samples. The cyclic voltammetry and charge -discharge characteristics implied the presence of surfactants enhances the energy storage within the MnO 2 structure. Addition of the surfactant at its optimum concentration greatly increased the EMD surface area, which in turn improved the cycle life of the EMD cathode. EMD obtained in the presence of 25, 50, 25 ppm of SOS, SDS, and STS respectively showed an improved cycle life relative to the EMD obtained in the absence of surfactant. EMD obtained without surfactant showed a capacity fade of 20 mAh g −1 within 15 discharge-charge cycles, while surfactant modified samples showed stable cyclic behavior of capacity 95 mAh g −1 even after 15 cycles. Global demand for new energy materials and energy storage devices is increasing rapidly and in parallel with the quest for alternative energy resources. Substantial research and development effort continues to be invested in the synthesis of an economically viable, ecofriendly storage device from a natural source. Among the various energy storage devices, alkaline rechargeable batteries have become the ultimate choice for energy storage systems in the portable electronics market as well as electric transport systems.1-3 Worldwide research and development programs in this area have been underway for more than a century, 2 with most attention focused on Zn-Mn, Ni-Cd, Ni-Fe, Ni-Zn, Ni-MH, and Li-ion rechargeable systems.4 Among these, ZnMn alkaline batteries have held a strong position in the battery market for many decades.Manganese dioxide, used as the active material in Zn-MnO 2 batteries, can be prepared both by chemical synthesis (chemical manganese dioxide, CMD) or electrochemical deposition (electrodeposited manganese dioxide, EMD) methods. Adequate primary Mn resources are available from which manganese dioxide can be produced, but the rapidly growing demand for manganese/manganese oxide has made it increasingly important to develop processes for economic recovery of manganese from low-grade mang...

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“…This reflects the TEM microscopy analysis and further supports the potassium intercalation. A further notable point in the RBS analysis, in Figure 10, is the high concentration of zinc for EMD 0 and Tw 30 electrodes. This shows that the zinc has been precipitated on the cathode as Zn(OH) 2 , thus inhibiting further electron transfer.…”

Section: G Electrochemical Activitymentioning

confidence: 93%

“…At the anode, the formation of MnO 2 does not take place in a single step; rather, Mn 3+ as an intermediate species is first formed [24,26,[30][31][32] together with some solid intermediates such as MnOOH(s) and Mn 2 O 3 (s). Being unstable in acidic solution, [2] During the electrodeposition process, Mn 3+ ions may be trapped in the MnO 2 lattice, possibly resulting in defects in the crystal structure.…”

mentioning

confidence: 99%

Effect of Non-ionic Surfactants and Its Role in K Intercalation in Electrolytic Manganese Dioxide

Metallurgical and Materials Transactions E

et al. 2014