Grilles n�gatives composites pour accumulateurs au plomb

Abstract

A new manufacturing process of negative composite grids for lead acid accumulators is described and discussed. In this process long grid preforms are woven with both conductive carbon fibres and nonconductive glass or polypropylene fibres. Then, lead is selectively deposited on to the conductive carbon fibres by continuous electroplating and, after rinsing and drying, the composite grids are stamped out of the impregnated preforms. In these grids, the carbon fibres, embedded with lead, form the connector and the grid-bars. The non-conductive glass or polypropylene fibres provide the necessary cohesion of the woven preform before electroplating, and retension of the active material pasted into the grids. These negative composite grids are about four times lighter than the classical lead-alloy grids of similar size. They exhibit the excellent corrosion resistance and hydrogen overpotential of pure lead. Negative plates made from these grids have been subjected to CEI-type charge-discharge cycles (12 h cycles, 75% discharge depth): they have undergone more than 250 cycles without deterioration.