The behavior of fibrous nickel electrodes working in Ni-H2 batteries has been studied in order to lighten these cells. The characteristics of the electrodes have been chosen taking into account the fact that a compromise between the swelling of electrodes and their capacity had to be defined. Cycling tests in accelerated geostationary mode are reported with this type of cell; 900 cycles have already been obtained without any decrease in performance. The end of discharge cell voltage is practically constant and a capacity equal to approximately 90% of the nominal capacity is recovered

L'architecture bipolaire, appliquee aux batteries alcalines et acides, permet l'obtention de batteries compactes aux caracteristiques massiques interessantes bien adaptees au fonctionnement aux forts regimes de charge et de decharge. Cette derniere caracteristique resulte de la collecte des charges assuree de facon homogene sur toute la surface des electrodes. L'industrialisation de la fabrication de ce type de batterie, realisee par empilement successif de plaques bipolaires, d'electrodes positives, de separateurs, d'electrodes negatives et de cadres d'etanchement, est aisee, ce qui limite les couts de realisation. Le dimensionnement de ces batteries peut etre adapte a la place disponible dans le materiel a equiper, ce qui assure un taux d'occupation optimal du volume, parametre important dans le cas des applications portables. L'aptitude au cyclage a ete demontree avec des collecteurs bipolaires a base d'un materiau composite plastique-metal ou plastique-carbone tant pour les batteries alcalines que pour la batterie acide au plomb.

Supercapacitors made of high-area electrode materials are complementary to batteries as far as electrical energy storage is concerned. Indeed, supercapacitors show low energy-density but high power-density. To achieve this, the time constant RC must be as low as possible, so the internal resistance R must be low. Apart from the effect of electrolyte resistivity and electrode thickness on the internal resistance, we show that the structure of the current collector acts on this parameter; the use of a three-dimensional current collector, such as metallic foam, results in an important decrease of the internal resistance of the cell.

Alcohol oxidation at PTFE-bonded electrodes has been studied with anodes fed with gaseous methanol. Polarization curves show activities 500 times higher than those obtained with methanol in solution.

Specific energies greater than 70 Wh-kg-1 can only be achieved for a 24 V Ni-Cd battery by reducing the weight of the bipolar collecting support. SORAPEC-NITECH has developed a lightweight foam substrate with which it is now possible to obtain bipolar electrodes with a collector thinner than 0.1 mm. These high volumetric energy density structures are well adapted for sealed battery applications. The performances of these batteries were studied as well as the optimization measures necessary to regulate the gas evolution in the cell during end of charge. The characteristic curves obtained with such cells during these tests are given

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This paper describes experimental work relating to the development of long cycle life Ni-Zn cells. In all cases, these cells were constructed with a large excess of electrolyte such that, at the oxidized state, the greater part of the zinc was dissolved as zincate ions. Two cell types were investigated: cells with flowing electrolyte and cells with stationary electrolyte. The second type required a combination of additives in solution and pulsed current during charge in order to obtain good cycle life.

Hydrogen oxidation has been studied in acidic medium on either tungsten or mixed tungsten-molybdenum carbides. The experiments have been carried out with bulk carbides and carbon-supported catalysts. In the latter case, much higher activities were obtained. The maximum current value obtained was approximately equal to 4.8-mu-A cm-2 (considering the CO adsorption surface area) with a tungsten carbide dispersed on active carbon. The mixed tungsten-molybdenum catalysts show lower activities than the value mentioned above.