method for producing an electrical lead acid accumulator accumulator and also available through the addition of electrolyte

摘要

1474802 Lead-acid battery GOULD Inc 8 July 1974 [9 July 1973 (2)] 30217/74 Heading H1B Crystal growth between the formed negative and positive plates of a dry-charged lead-acid battery which may occur before activation of the battery by the addition of electolyte thereto, is prevented by treating the plates with a metal sulphate soluble in sulphuric acid or water. The preferred sulphate is of sodium, other suitable sulphates being of K, Li, Mg, Ca, Zn, and Al; additionally, the sulphates of Be, Ce, In, La, Sn, Tl, Zr and Rb, may be used. In one method of making the battery the metal sulphate is added to the formation electrolyte, viz. H 2 SO 4 solution of S.G. in the range 1À020- 1À100, the metal sulphate being present in an amount of about 2 per cent by wt. The electrolyte is subsequently removed by inverting the battery. In a preferred method, the formation electrolyte does not contain the metal sulphate and after removal of this electrolyte the battery is filled with a H 2 SO 4 rinse solution of S.G. in the range 1À200-1À400, this solution containing 0À05-5 per cent by wt. of the metal sulphate. The plates and separation are soaked for about 10 minutes in the rinse solution which may be stirred and the solution is then removed by inverting the battery. In another method the metal sulphate is dissolved in water in an amount 0À05-5 per cent by wt. and the battery is filled with this solution either after draining the formation electrolyte or after draining the rinse solution, the water being subsequently drained from the battery. Whatever method is used for adding the metal sulphate the battery is subsequently sealed in a manner such that gas-pressure build-up within the battery may be vented and slight ingress of air into the battery is permitted. The very small amount of oxygen permitted to enter the battery during its shelflife tends to equalize the self-discharge of the positive and negative plates and reduces the tendency for the initial battery performance to be positive plate limited. The vent aperture may be circular in shape and have a diameter of 0À0005-0À006 inch. A venting arrangment, Figs. 4, 5, comprises two groups 35 of three vent caps each having a main body 36 formed with normal labyrinth passages (not shown) for breathing of the battery after it has been made operational. During the battery shelf-life the cell apertures 34 in the battery lid 33 are sealed by plugs 38 each having a small vent aperture 40 (referred to above) and the caps 35 are retained by flanges 42 cooperating with upstanding portions 43 on the seal plugs 38. The battery is brought into operation by removing the plugs 38 by tabs 41, filling with electrolyte, and engaging the cap flanges 42 in the apertures 34. In a modified venting arrangement (Figs. 7-9, not shown) the small vent aperture is replaced by a small groove formed in the outer surface of the side wall of the seal plug.