Composite current collector and methods therefor

Abstract

Contemplated bipolar lead acid batteries include a bipole assembly with a monolithic or composite current collector that is in contact with the PAM. Especially preferred current collectors have a substrate formed from pure lead and grid formed from a lead alloy, wherein the interface between the grid and substrate is formed via electroforming and / or resistance welding. Particularly preferred batteries are configured as deep cycle batteries and have a low ratio between the surface area of the grid and the weight of the PAM.

Description

[0001]This application claims priority to our copending U.S. provisional application with the Ser. No. 61 / 179,609, which was filed May 19, 2009.FIELD OF THE INVENTION[0002]The field of the invention is current collectors, and especially as it relates to current collectors in bipolar lead acid batteries (BLAB).BACKGROUND OF THE INVENTION[0003]It is well-known in the art of lead acid battery manufacture that pure lead has a relatively high resistance to corrosion in sulfuric acid containing electrolytes due to the insulating layer of PbSO4 / PbOx (1<x<2) that is formed in the electrolyte. Thus, and at least at first glance it appears desirable to form in a lead battery a positive plate with a grid structure made from pure lead since the PbSO4 / PbOx layer acts as semi-permeable membrane and blocks the transport of SO42− and / or HSO4−species. In most cases, the PbSO4 / PbOx layer has a thickness of about four microns and tends to stay at that value through the life of a lead acid batter...

AI Technical Summary

Benefits of technology

[0007]The present invention is directed to devices and methods for bipolar batteries, and especially bipolar lead acid batteries with substantial improved performance and power-to-weight ratio in which a monolithic current collector combines advantages of improved resistance to oxidation and conductivity.

Problems solved by technology

However, lead grid structures from pure lead are unfortunately not suitable for deep cycling applications as the PbSO4 / PbOx layer that is formed during operation also acts as an insulator with very high electric resistance, which in turn results in a premature capacity loss of the cell.

While such collectors may reduce or even entirely avoid the formation of the PbSO4 / PbOx layer, other disadvantages nevertheless remain.

For example, manufacture of such composite structures will typically require lamination, which tends to be instable over prolonged times. Furthermore, the amount of added alkaline metal or alkaline earth metal is typically relatively high and thus often interferes with material properties of the alloy.

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