SE367092

1282766 Sealed, secondary lead cells MATSUSHITA ELECTRIC INDUSTRIAL CO Ltd 6 Nov 1969 [6 Nov 1968 19 Sept 1969 (2)] 54458/69 Heading H1B Secondary lead cells with substantially sealed containers comprise a reactive element 24 in communication with the gas phase 22 inside the cell and with the outside air 23 which includes a catalyst for promoting reaction between excess hydrogen produced in the cell and atmospheric oxygen and which has water-repellent properties, and an electrolyte-impregnated body 25 closely adjacent element 24 and partly immersed in the electrolyte 13. As shown in Fig. 1 the cell also contains an auxiliary hydrogen-consuming electrode 16 connected to the positive electrode 11 via a potential control element 17, e.g. a diode or a non-linear resistor such as a sintered ZnO body. Body 25 serves as a wick to keep the reactive element 24 in contact with electrolyte. Element 24 may act by catalysing the oxidation of hydrogen inside the cell by oxygen from outside the cell. At the same time its hydrophobic nature prevents the escape of electrolyte. Element 24 may be a homogeneous body comprising a particulate support material, a catalyst, such as a platinum group metal, and a water repellent material e.g. paraffin or a hydrophobic polymer. In another embodiment the catalyst may be in one layer 24a of the element which is in contact with the electrolyte-impregnated body 25 whilst the hydrophobic material is in a second layer 24b facing the atmosphere (Fig. 3, not shown) or to prevent distortion of the element during its production by moulding a third layer 24c of similar composition to the catalyst layer 24a but lacking the catalyst may be provided between hydrophobic layer 24b and the atmosphere (Fig. 4).