Charge Preservation in Negative Electrodes by a PbO Layer

The drying of negative plates is not possible without precautions, because of the tendency to spontaneous oxidation. This oxidation reaction is much ac-celerated by water, and the active material of a moist negative electrode is spon-taneously converted into lead oxide when exposed to air. When, on the other hand, the charged plate is dry, a thin layer of oxide covers the surface of the active material, and prevents 

The dried plates can be stored for a practically unlimited time without losing capacity or ageing. This is true also for complete batteries that are assembled but not yet filled with electrolyte. 

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