Zeta potential at sulphuric acid-battery separator interface

Electrokinetic zeta potential of commercial battery separators has been determined using streaming potential measurements. The effect of pore size and other pore properties in conjunction with zeta potential on electrical resistance of battery sepqatora is brought out from expefimental data. Zeta potential effects with high positive charge accumulation affect the electrical resistance of submicroporous separator

Electron microscopic investigations on the morphology and crystal growth characteristics of black nickel thin films

Electron microscopy studies were made on thin films of black nickel coatings during the initial stages of electrocrystallisation. Ni-Zn-S, Ni-Zn-Fe-S, Ni-Cd-Zn-Fe-S and Ni-Mo-Fe-Mn were the four different types of black coatings examined. The coatings were electrocrystallised from sulphate baths with ammonium thiocyanate as the blackening agent in most experiments. Interesting morphological and crystal growth patterns were observed for the different types. Introduction of iron significantly alters the crystal growth characteristics. The mechanical and optical absorption properties of these films can be understood from the crystal growth behaviou

Influence of deposition current density on the magnetization behaviour in electrodeposited Ni-Mn alloys

Ni-Mn alloys were electrodeposited at different current densities from sulphate baths and their magnetization behaviours at different fields were studied. The magnetization decreases with increase in deposition CD in the absence of additives. The magnetization behaviour of Ni-Mn is different from that of its counterpart i.e. the electrodeposited Fe-Mn system. The system is free from pronounced ferromagnetic coupling between Mn spins. The magnetic moments in high field regions are heavily influenced by the presence of Mn spin

A programmable multi purpose charging system for electrochemical secondary power sources

Design details of a microprocessor based multipurpose battery charger is described. The main characteristics of the charger are that it can be CC or CV mode charging, with desired taper charging or multistep charging variitions. Provision for temperature sensing of the battery and corresponding charge corrections are built in.Software for three types of charging is describe

Electron paramagnetic resonance in pyrolusite and cryptomelane manganese dioxides

Electron paramagnetic resonance spectroscopy has been applied to identify the singular structural features of pyrolusite (b) and cryptomelane(a) manganese dioxides. At 77 K, the derivative linewidth of pyrolusite is reduced to that of cryptomelane and the Ms = -3/2 spin stacts in cryptomelane are affected by the changes in crystal field. Isothermal heating of cryptomelane in air at 100 deg.C for two days affects the Ms = -5/2 and Ms = -3/2 levels. The results seem to confirm the partial collapse of the lattice due to release of molecular water on heatin

Electrocatalytic properties of electrodeposited Ni–Mn–S system in alkaline electrolytes

Ni–Mn–S was electrodeposited on mild steel from sulphate–thiocyanate baths. The resultant materials were evaluated for electrocatalytic activity towards hydrogen evolution reaction in 30 wt-% KOH. Incorporation of sulphur in Ni–Mn improves the electrocatalytic activity giving a sizeable increase in exchange current density j0. In Ni–Mn the hydrogen evolution reaction is through a Volmer–Tafel mechanism whereas in the Ni–Mn–S system follows a Tafel mechanism. The influence of deposition current density (CD) was investigated. Electrocatalytic activity increased with increase in the deposition CD and was maximum in samples deposited at 80 mA cm22

Influence of plating variables on the electrocatalytic behavior of Ni-Mn electrocoated cathodes for alkaline water electrolysis

The electrocatalytic properties of Ni-Mn codeposits as a function of plating parameters is studied in detail. Higher current densities, moderate temperature and baths of neutral pH yield good electrocatalyst

Electron microscope observations on electrolytic Ni-Mo-Fe coatings

Selected Ni-Mo-Fe coatings were electrodeposited from ammoniacal citrate baths by varying the plating parameters. Their surfaces were examined by scanning electron microscopy for topography and SE imaging. Observed electrocatalytic, corrosion and optical properties of the coatings were found to be dependent on surface structure. The results were also used to understand the influence of electrodeposition variables. The plating diameters were found to have strong influence on the surface structure. Increases in deposition CD resulted in phase segregation in these materials. Also it was confirmed that increases in molybdenum content of the plating bath introduced heterogeneity in the plated samples with occurrence of more than one phase. Multinucleation in crystal structure was observed in samples electrodeposited at near neutral pH levels, again due to increased molybdenum content. The coatings reveal network formation at 300 deg. C. Inclusion of Mn was helpful in obtaining homogeneous deposit

Electrochemical properties of MmNi3.03Si0.85Co0.60Mn0.31Al0.08 hydrogen storage alloys in alkaline electrolytes—A cyclic voltammetric study at different temperatures

The cyclic voltammetric behavior of MmNi3.03Si0.85Co0.60Mn0.31Al0.08-based metal hydride electrode was studied in alkaline electrolytes at various temperatures (303, 308, 318 and 328 K). Electrochemical parameters such as limiting current density and corrosion potential were determined at these temperatures. The corrosion potential became more negative with increasing temperature. Hydrogen diffusivity was also found to increase with increasing temperature. From electrochemical discharge experiments, it was concluded that the charge transfer process was the rate-determining step

Linear sweep voltametry studies on oxygen reduction of some oxides in alkaline electrolytes

The study uses linear sweep voltametry (LSV) to observe the efficiency of oxygen reduction on some oxides and their mixtures in 6 M KOH at 25 C. The investigated materials are Ag2O, MnO2, Sm2O3, Dy2O3 and NdO2. The electrocatalytic oxygen reduction reactions (ORR) on Teflon-bonded, oxide þ graphite electrodes are studied. The oxygen reduction potentials for electrodes containing these materials as catalyst are seen as 60.67, 270.31, 111, 159.58 and 130.24 mV, respectively. Mixture combinations of these oxides give a higher ORR peak current thereby showing evidence of synergetic effect. Air–MH cells using some of the above investigated oxides as catalyst for air electrode are constructed and studied. Best performance is obtained with silver oxide. The LSV findings are in accordance with air–MH cell charge/discharge experiments and for best performance prefer shift of the ORR onset potential to more positive positions