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

Abstract

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...

Electrolytic manganese dioxide (EMD): a perspective on worldwide production, reserves and its role in electrochemistry

“…[36][37][38][66][67][68] The process ow sheet for production of EMD from the above discussed secondary ores was shown in Fig. removal of residual Mn(II) from ammoniacal leach liquor by oxidizing under oxygen over pressure.…”

“…[36][37][38][66][67][68]76,[91][92][93][94][95][96][97][98][99][100][101][102] Apart from sulphate bath, EMD can also be produced from chloride bath. Usually EMD is prepared from manganese sulfate-sulphuric acid bath.…”

“…The presence of non-ionic surfactants (Triton X-100 and Tween 20) enhances the electrochemical activity of EMD, not only by modifying the structure but also by increasing the BET surface area and porosity of the EMD samples. 38 Electrochemical studies of the electrodeposited EMD in the presence of STS as a surfactant indicate it is a potential candidate for use as electrode material in alkaline rechargeable batteries. Optimum concentration of surfactant must be essential for the positive consequences in the performance and behaviour of the EMD.…”

Electrodeposition of Pluronic F127 assisted rod-like EMD/carbon arrays for efficient energy storage

“…Electrolytic manganese dioxide (EMD) is preferred over natural and chemical manganese dioxides obtained from other sources due to its purity and better chemical reactivity [9][10]. On the other hand, surfactant as an additive also plays an important role in enhancing the rechargeability of EMD by modifying the structure to a larger extent [20][21][22][23][24][25][26][27][28]. It is interesting to note that Li-ion batteries, containing manganese derived from high purity EMD, are now in high demand for power vehicles, thus escalating the demand for EMD further [11].…”

“…EMD is one of the widely used cathode materials for alkaline batteries, lithium manganese primary batteries. The reported surfactants in the literature [20][21][22][23][24][25][26][27][28] are quite well known to this field and are pertained to cationic or anionic. EMD exhibits the greatest battery activity for most applications as quoted earlier.…”