COMPOSITE CURRENT COLLECTOR AND METHODS THEREFOR
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.
1 . A bipole assembly for use in a bipolar lead acid battery, comprising:
a welded or monolithic composite current collector that comprises a conductive substrate formed from a first metal composition and an electroformed grid structure;
wherein the electroformed grid structure is conductively coupled to a first side of the substrate and formed from a second metal composition, and wherein the first and second metal composition are not the same.
2 . The bipole assembly of claim 1 wherein the first metal composition is pure lead and wherein the second metal composition is a lead alloy.
3 . The bipole assembly of claim 2 wherein the lead alloy comprises an alkaline earth metal, an alkaline metal, or tin.
4 . The bipole assembly of claim 1 further comprising a non-conductive grid coupled to the substrate on a second side of the substrate that is opposite the first side, and further comprising a negative active material (NAM) contacting the non-conductive grid and the second side of the substrate.
5 . The bipole assembly of claim 4 wherein the negative active material (NAM) is in-tank formed negative active material (NAM).
6 . The bipole assembly of claim 1 further comprising a positive active material (PAM) contacting the electroformed or resistance welded grid structure and the first side of the substrate.
7 . The bipole assembly of claim 6 wherein the positive active material (PAM) is in-tank formed positive active material (PAM).
8 . The bipole assembly of claim 7 wherein the grid structure has a surface area S grid and wherein the PAM has a weight W PAM , and wherein the ratio of W PAM to S grid is between 0.65-1.1 g/cm 2 .
9 . The bipole assembly of claim 7 wherein the grid structure has a surface area S grid and wherein the PAM has a weight W PAM , and wherein the ratio of W PAM to S grid is between 0.8-1.0 g/cm 2 .
10 . The bipole assembly of claim 1 wherein the substrate is configured as a composite substrate in which a non-conductive polymer carrier is coupled to the substrate opposite the first side, wherein the polymer carrier has a plurality of openings that allow formation of a conductive path between the substrate and another conductive material located on an opposite side of the carrier.
11 . A bipolar lead acid battery comprising the bipole assembly of claim 1 .
12 . The bipolar lead acid battery of claim 11 wherein the battery is configured as a valve regulated lead acid battery.
13 . The bipolar lead acid battery of claim 11 wherein the battery is configured as a deep cycle battery.
14 . A method of forming a bipole assembly for a bipolar lead acid battery, comprising a step of resistance welding a lead alloy grid structure onto a lead substrate, or gradually building a lead alloy grid structure onto a lead substrate, or gradually forming a lead substrate onto a lead alloy grid structure to thereby form a composite or monolithic current collector structure.
15 . The method of claim 14 wherein the step of gradually building is selected from the group consisting of electroforming, electroplating, vapor depositing, redox depositing.
16 . The method of claim 14 wherein the lead alloy comprises an alkaline earth metal, an alkaline metal, or tin.
17 . The method of claim 14 further comprising a step of coupling to the lead alloy grid structure and the first side of the substrate a positive active material (PAM).
18 . The method of claim 16 wherein the lead alloy grid structure has a surface area S grid and wherein the PAM has a weight W PAM , and wherein the ratio of W PAM to S grid is between 0.65-1.1 g/cm 2 .
19 . The method of claim 16 wherein the lead alloy grid structure has a surface area S grid and wherein the PAM has a weight W PAM , and wherein the ratio of W PAM to S grid is between 0.8-1.0 g/cm 2 .
20 . The method of claim 14 further comprising a step of coupling a non-conductive grid to the lead substrate on a side of the substrate that is opposite the side onto which the grid structure is formed, and further in-tank forming a negative active material (NAM) onto the non-conductive grid and the opposite side.
21 . The method of claim 14 wherein the lead substrate is configured as a composite substrate in which a non-conductive polymer carrier is coupled to the lead substrate opposite the side onto which the grid structure is formed, wherein the polymer carrier has a plurality of openings that allow formation of a conductive path between the lead substrate and another conductive material located on the opposite side of the carrier.