J. Mrha

The influence of preparation conditions on the electrochemical behaviour of CuO in a Li/CuO cell

Abstract A dozen CuO samples prepared under various conditions and from different starting materials were evaluated as cathode materials for a primary Li/CuO cell. The “thin electrode” method was used for rapid evaluation of the samples. Both coulombic efficiency and discharge voltage depend considerably on the method of synthesis. No correlation was found between the specific surface area and the resistivity of the samples on the one hand and the cathode performance on the other. Best results were obtained from CuO prepared by the oxidation of Cu 2 O under controlled temperature and time of oxidation.

Plastic-bonded electrodes for nickelcadmium accumulators. X. The nature of the second discharge step of nickel oxide electrodes

Abstract The second discharge step of nickel oxide accumulator electrodes is suppressed in the presence of a Teflon binder and/or cobalt, cerium, or manganese hydroxide, whereas the first discharge step increases. This behaviour is discussed in terms of ohmic resistance effects and semiconducting properties of the active material.

Plastic bonded electrodes for nickel-cadmium accumulators. III. Influence of active layer composition on galvanostatic and potentiostatic discharge curves

Abstract Studies on the addition of a conducting component (carbon black, graphite, carbonyl nickel) and poly(tetrafluoroethylene) as binder to the active material used in pocket-type nickel oxide electrodes have shown that the second discharge step, which is observed in the discharge curve of a pressed nickel oxide electrode in the potential range from −100 to −600 mV (Hg/HgO), can be markedly influenced or fully suppressed as in the case of a sintered nickel oxide electrode. The existence of this discharge step is attributed to differences in the ohmic contacts of the electroactive particles in the pressed electrode.

Impedance characteristics of sealed lead/acid cells during galvanostatic charge

Abstract The electrochemical impedance of a model hermetic lead accumulator and its electrodes was measured during continuous or interrupted charging either in potentiostatic (at 10 4 -10 −3 Hz) or in galvanostatic (at 0.1 Hz) mode. The impedance characteristics of the negative electrode changed considerably during the second half of charging and during overcharging. The impedance curve at 0.1 Hz measured during continuous galvanostatic charging can be used to indicate the state of full charge of the cell.

Oxygen cycle in sealed leadacid batteries

Abstract This review is concerned with problems associated with the evolution of hydrogen and oxygen and their ionization in sealed leadacid batteries. The roles of the separator and of admixtures in the battery constituents are discussed in detail, and the possible applications of the batteries are briefly evaluated.

Plastic bonded electrodes for nickel-cadmium accumulators II. Basic electrochemical parameters of the nickel oxide electrode

Abstract Plastic bonded nickel oxide electrodes, prepared at normal temperature by one-stage rolling onto a current collector of steel net or perforated sheet of a mixture of active mass used in pocket-type electrodes, a conducting component and a PTFE binder, were tested in alkaline electrolyte. At current loads of 3–100 mA/cm 2 the type of conducting admixture, the current collector and its surface treatment were found to have a pronounced influence on the current carrying capability of the electrode. The electrode performance, especially at 100 mA/cm 2 is dependent not only on the composition of the active layer but also on the quality (or nature) - but not degree of contact between it and the current collector.

Plastic bonded electrodes for nickel-cadmium accumulators I. Cadmium electrode

Abstract Plastic bonded cadmium electrodes of outstanding electrochemical properties, capable of replacing the commercial pocket-type electrodes of vented NiCd batteries, were produced by rolling the active mass, blended with powdered plastic polymer, onto a metallic current collector at normal temperature.

Study of sealed lead/acid cells

Abstract Based on barodynamic characteristics, both the oxygen pressure and the oxygen reduction current at the negative electrode in a sealed lead/acid cell were followed. These data together with potentiodynamic characteristics were used to characterize the time course of the oxygen cycle and its efficiency. Data about the partial pressure of hydrogen were also obtained and experimentally verified. Calculations were made on the assumption that at the positive electrode only oxygen is evolved and at the negative electrode only hydrogen evolution and oxygen reduction proceed.

Plastic-bonded electrodes for nickel—cadmium accumulators IV. Some specific problems of the positive active layer

Abstract The active layer of plastic-bonded nickel oxide electrodes, undergoes expansion, during discharging and contraction during charging; the, latter however does not fully compensate for the expansion. These volume changes can be made reversible by the action of an external pressure. The electrochemical behaviour of the conductive components, carbon black and graphite, shows, more or less severe corrosion during anodic current loading.

Influence of Fe(III) ions on the nickel hydroxide electrode during long-term cycling

Abstract The iron-poisoning effect of sintered nickel oxide electrodes in alkaline accumulators during long-term cycling has been studied by electrochemical mea