Avijit Biswal

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

Electrolytic manganese dioxide (EMD) is the critical component of the cathode material in modern alkaline, lithium, and sodium batteries including electrochemical capacitors and hydrogen production. In terms of environmental and cost considerations, EMD is likely to remain the preferred energy material for the future generation, as it has been in recent decades. Diminishing fossil fuels and increasing oil prices have created the need to derive energy from sustainable sources. The energy storage device from alternative and inexpensive sources, such as low grade manganese ores, has a niche in the renewable energy and portable electronics market. Despite vast manganese sources along with the current activity in producing modified EMD materials from secondary sources, to a surprise, India mostly imports EMD to meet its demand. Keeping this in view, a comprehensive review has been prepared on the synthesis, physical and electrochemical characterization of EMD produced from synthetic solutions and secondary sources. This review summarizes the available EMD sources in the world including Indian deposits and the recent investigations of fundamental advances in understanding the electrochemical mechanism involved in aqueous rechargeable batteries and electrochemical capacitors, thus leading to an improved energy storage performance, which is essential for their long term use in storing renewable energy supply.

Electrodeposition of manganese dioxide: effect of quaternary amines

The effect of quaternary ammonium salts (tetraethyl ammonium bromide, tetrapropyl ammonium bromide, and tetrabutyl ammonium bromide) on the structural, morphological, and electrochemical characteristics of electrolytic manganese dioxide (EMD) obtained from acidic aqueous sulfate solution has been investigated. Physical characterization of the EMD was achieved by X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, differential thermal analysis, and Fourier transform infrared spectroscopy. The charge–discharge profile of the materials was determined to evaluate their potential for alkaline battery applications. The presence of these quaternary ammonium salts as organic additives in the solution increased the current efficiency while decreasing energy consumption during electrochemical deposition of manganese dioxide (MnO2). All the additives influenced the discharge characteristics of the EMD samples significantly, producing a cathode material with increased cumulative discharge capacity relative to EMD prepared in the absence of additives. This is attributed to the ability of the additives to affect the particle size and morphology, and therefore electrochemical activity, of electrodeposited materials; the effects in the case of the additives investigated in this work were positive, producing a material with potential application to battery technology.

Synthesis and characterization of fibrous nickel hydroxide obtained from spent nickel catalyst

The recovery of nickel from spent nickel catalyst for the preparation of nickel hydroxide was studied. Nickel was extracted from the spent catalyst by acid leaching with 1 mol/L sulfuric acid at 90 C. Purified nickel solution was used in the preparation of nickel hydroxide. Three different methods, namely urea hydrolysis, conventional, and hydrothermal methods, of precipitation using NaOH were employed to get various nickel hydroxides samples named as Ni(OH) 2-U, Ni(OH)2-C, and Ni(OH)2-H, respectively. Hydrothermal treatment induced better crystallinity in the Ni(OH)2 compared with conventional method. Both Ni(OH)2-C and Ni(OH) 2-H samples have mixed phases of β-Ni(OH)2 and α*-Ni(OH)2·0.75H2O phases, whereas Ni(OH)2-U has only α*-Ni(OH) 2·0.75H2O. TEM image of Ni(OH)2-U sample shows rod-like Ni(OH)2 structures. Among all, Ni(OH)2-U shows the best electrochemical activity.

Erratum to: Electrodeposition of manganese dioxide: effect of quaternary amines

The effect of quaternary ammonium salts (tetraethyl ammonium bromide, tetrapropyl ammonium bromide, and tetrabutyl ammonium bromide) on the structural, morphological, and electrochemical characteristics of electrolytic manganese dioxide (EMD) obtained from acidic aqueous sulfate solution has been investigated. Physical characterization of the EMD was achieved by X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, differential thermal analysis, and Fourier transform infrared spectroscopy. The charge–discharge profile of the materials was determined to evaluate their potential for alkaline battery applications. The presence of these quaternary ammonium salts as organic additives in the solution increased the current efficiency while decreasing energy consumption during electrochemical deposition of manganese dioxide (MnO2). All the additives influenced the discharge characteristics of the EMD samples significantly, producing a cathode material with increased cumulative discharge capacity relative to EMD prepared in the absence of additives. This is attributed to the ability of the additives to affect the particle size and morphology, and therefore electrochemical activity, of electrodeposited materials; the effects in the case of the additives investigated in this work were positive, producing a material with potential application to battery technology.