Method for Forming an Electrical Connection to a Conductive Fibre Electrode and Electrode So Formed

Abstract

A method for forming an electrical connection to a microscale electrically conductive fibre material electrode element, such as a carbon fibre electrode element of a Pb-acid battery, comprises pressure impregnating into the fibre material an electrically conductive lug material, such as molten Pb metal, to surround and/or penetrate fibres and form an electrical connection to the fibre material and provide a lug for external connection of the electrode element. Other methods of forming a lug for external connection are also disclosed.

1 . A lead acid battery or cell including at least one electrode comprising as a current collector a conductive fibre material having an average interfibre spacing of less than 250 microns, comprising an electrically conductive lug material pressure impregnated into a lug zone part of the fibre material surrounding and/or penetrating the fibres and forming an electrical connection to the fibre material in said lug zone and providing a lug for external connection of the electrode element, and comprising and an active material in at least a part of the conductive fibre material other than in said lug zone, and wherein a surface to volume ratio of Pb particles in the active material is at least about 3 times greater than a surface to volume ratio of lug material in the lug zone. 
     
     
         2 . A lead acid battery or cell according to  claim 1  wherein the surface to volume ratio of Pb particles in the active material is at least about 10 times greater than a surface to volume ratio of lug material in the lug zone. 
     
     
         3 . A lead acid battery or cell according to  claim 1  wherein the surface to volume ratio of Pb particles in the active material is greater than about 2 m 2 /cm 3  and the surface to volume ratio of lug material in the lug zone is less than about 0.5 m 2 /cm 3 . 
     
     
         4 . A lead acid battery or cell according to  claim 1  wherein the surface to volume ratio of Pb particles in the active material is greater than about 1 m 2 /cm 3  and the surface to volume ratio of lug material in the lug zone is less than about 0.5 m 2 /cm 3 . 
     
     
         5 . A lead acid battery or cell according to  claim 1  wherein the lug material comprises a metal that is either Pb or a Pb alloy Zn or a Zn alloy, or Cd or a Cd alloy. 
     
     
         6 . A lead acid battery or cell according to  claim 1  wherein the active material contacts the lug where the conductive fibre material enters the lug and electrically connects direct to the lug. 
     
     
         7 . A lead acid battery or cell according to  claim 1  wherein the electrically conductive lug material is impregnated between at least 50% of the fibres in said lug zone part of the conductive fibre material. 
     
     
         8 . A lead acid battery or cell according to  claim 1  wherein the electrically conductive lug material is impregnated between at least 70% of the fibres in said lug zone part of the conductive fibre material. 
     
     
         9 . A lead acid battery or cell according to  claim 1  wherein the conductive fibre material has an average interfibre spacing of less than 100 microns. 
     
     
         10 . A lead acid battery or cell according to  claim 1  wherein active material contacts the lug where the fibre material enters the lug, and electrically connects direct to the lug. 
     
     
         11 . A lead-acid battery or cell according to  claim 1  in which the electrical resistance of the electrical connection between the lug material and the conductive fibre material in said lug zone is less than the resistance of the active material by at least 10% when the battery or cell is 10% charged. 
     
     
         12 . A lead acid battery or cell including at least one electrode comprising as a current collector a conductive fibre material having an average interfibre spacing of less than 250 microns, comprising an electrically conductive lug material in a lug zone part of the conductive fibre material surrounding and/or penetrating the conductive fibre material and forming an electrical connection to the conductive fibre material in said lug zone part of the conductive fibre material and providing a lug for external connection of an electrode element, the electrically conductive lug material impregnating between at least 30% of the fibres in said lug zone part of the conductive fibre material, the electrode also comprising an active material in an active area comprising at least a part of the conductive fibre material other than in said lug zone, the active material impregnating the conductive fibre material in said active area, and wherein a surface to volume ratio of Pb particles in the active material is at least about 3 times greater than a surface to volume ratio of lug material in the lug zone. 
     
     
         13 . A lead acid battery or cell according to  claim 12  wherein the surface to volume ratio of Pb particles in the active material is at least 10 times greater than a surface to volume ratio of lug material in the lug zone. 
     
     
         14 . A lead acid battery or cell according to  claim 12  wherein the surface to volume ratio of Pb particles in the active material is greater than 2 m 2 /cm 3  and the surface to volume ratio of lug material in the lug zone is less than 0.5 m 2 /cm 3 . 
     
     
         15 . A lead acid battery or cell according to  claim 12  wherein the surface to volume ratio of Pb particles in the active material is greater than 1 m 2 /cm 3  and the surface to volume ratio of lug material in the lug zone is less than 0.5 m 2 /cm 3 . 
     
     
         16 . A lead acid battery or cell according to  claim 12  wherein the lug material comprises a metal that is Pb or a Pb alloy, Zn or a Zn alloy, or Cd or a Cd alloy. 
     
     
         17 . A lead acid battery or cell according to  claim 12  wherein the electrically conductive lug material is impregnated between at least 50% of the fibres in said lug zone part of the conductive fibre material. 
     
     
         18 . A lead acid battery or cell according to  claim 12  wherein the electrically conductive lug material is impregnated between at least 70% of the fibres in said lug zone part of the conductive fibre material. 
     
     
         19 . A hybrid automotive vehicle comprising a battery according to  claim 1 . 
     
     
         20 . A hybrid automotive vehicle comprising a battery according to  claim 12 .