Lead acid cells and batteries

Claim 2

A sealed lead acid cell having electrodes comprising metallic supports which minimize the evolution of hydrogen and which are separated by at least one layer of separator material, the support of the positive electrode or electrodes having positive active material deposited thereon and the support of the negative electrode or electrodes having negative active material deposited thereon, the capacity of the negative electrodes being arranged to be at least as great as the capacity of the positive electrodes, characterized in that the supports for the electrodes are in the form of a mesh or grid affording an integral current collecting strip or bar along at least one edge which will be the top or bottom edge of the structure when assembled in a cell wherein the thickness of the electrodes is less than 3 mm, the thickness of the separator is in the range of 10% to 200% of the thickness of the electrodes and the volume, E, of the electrolyte in the cell in relation to the sum of the pore volume of the separators, X, and the pore volume of the positive and negative active materials, Y, is not greater than 2X + Y.

Claim 3

The sealed lead acid cell of claim 1, in which the positive active material paste composition contains 23 to 57 parts by weight of liquids per 100 parts by weight of the lead content of the active material and from 0.01 to 1.0 parts by weight of silica calculated as SiO 2 per 100 parts by weight of active material (calculated as PbO 2 ).

Claim 4

The sealed lead acid cell of claim 1, in which the negative active material includes at least 0.1% by weight of lignin derived lignosulphonate material.

Claim 5

The sealed lead acid cell of claim 1, in which the separator material comprises a non-woven fibrous material fibres of which are fused to other fibres, substantially all of the fibres being fused to at least one other fibre, the material being 0.1 to 1 mm thick and having a permeability to air of 0.0001 to 0.1 liters per second cm head of water per square cm, and a tensile strength of at least 0.01 kgs per sq. mm.

Claim 6

The sealed lead acid cell of claim 4, in which the fibres of the separator material are 25 to 150 mm long and have diameters in the range of 5 to 50 microns.

Claim 7

The sealed lead acid cell of claim 4, in which the fibres of the separator which are fused to other fibres have one such fused point of contact with another fibre every 1 to 10 mm of their length.

Claim 8

The sealed lead acid cell of claim 4, in which the separator material weighs 100 to 250 grams/sq meter as is 0.5 to 0.8 mm thick.

Claim 9

The sealed lead acid cell of claim 1, in which the separator material has compressed porous regions having a thickness D which is related to the thickness C of the remainder of the material in the range of ratios 1:10 to 1:2.

Claim 10

The sealed lead acid cell of claim 8, in which the area of the separator occupied by such compressed regions is 10% to 50% of the total plan area of the separator.

Claim 11

The sealed lead acid cell of claim 8, in which the compressed regions of the separator material are provided as strips of equal width spaced equal distances apart and arranged to extend up and down in the cell as assembled.

Claim 12

The sealed lead acid cell of claim 1, in which the crosssection area of the current collecting bar or strip is in the range 2 to 10 times that of the narrowest mesh elements of the structure.

Claim 13

The sealed lead acid cell of claim 1, in which the height of the electrodes and thus the separator is not greater than 150% of the free wicking height, wherein the free wicking height is the height to which 1.38 sp. gr. sulphuric acid rises up a strip of the separator material when said material is suspended vertically above a bath of the acid with 1 cm of the end of the strip below the surface of the acid and the strip and bath are enclosed in a sealed environment at 20° C for 1 hour so as to reach equilibrium.

Claim 14

The sealed lead acid cell of claim 1, in which the ratio of the positive and negative active masses combined in grams to the separator height in cms is in the range 13:1 to 30:1.

Claim 15

The sealed lead acid cell of claim 1, in which a porous electrolyte retaining reservoir, capable of holding at least 10% of the amount of electrolyte absorbed by the separators, is located in the cell and is arranged in wicking relationship to the separators.

Claim 16

The sealed lead acid cell of claim 14, in which the reservoir comprises a pad or coil separator material.

Claim 17

The sealed lead acid cell of claim 1, in which the density of the positive active material is in the range 3.2 to 3.8 grams per cc.

Claim 18

The sealed lead acid cell of claim 1, in which the specific gravity of the electrolyte is in the range 1.33 to 1.41.

Claim 19

The sealed lead acid cell of claim 1, in which the electrode terminals are burnt together with a 98% lead 2% tin solder.

Claim 20

A sealed lead acid cell characterized in that it has electrodes comprising metallic supports which minimize the evolution of hydrogen and resist deformation under their own weight, the supports for the electrodes being in the form of a mesh or grid affording an integral current collecting strip or bar along at least one edge which will be the top or bottom edge of the structure when assembled in a cell and which are separated by at least one layer of separator material, the support of the positive electrode or electrodes having positive active material deposited thereon, the deposited active material paste composition consisting of from 23 to 57 parts by weight of liquids per 100 parts by weight of the lead content of the active material and from 0.01 to 1.0 parts by weight of silica calculated as SiO 2 per 100 parts by weight of active material (calculated as PbO 2 ) and the support of the negative electrode or electrodes having negative active material deposited thereon, the deposited negative active material being formed from a negative paste active material composition which includes at least 0.1% by weight of lignin derived lignosulphonate material, and in which the capacity of the negative electrodes is arranged to be at least as great as the capacity of the positive electrodes, the thickness of the electrodes is less than 3 mm, the thickness of the separator is in the range of 10% to 200% of the thickness of the electrodes and the volume, E, of electrolyte in the cell in relation to the sum of the pore volume of the separators, X, and the pore volume of the positive and negative active materials, Y, is not greater than 2X + Y.

Claim 21

A sealed lead acid cell characterized in that it has electrodes comprising metallic supports which minimize the evolution of hydrogen and resist deformation under their own weight, the supports for the electrodes being in the form of a mesh or grid affording an integral current collecting strip or bar along at least one edge which will be the top or bottom edge of the structure when assembled in a cell and which are separated by at least one layer of separator material, the support of the positive electrode or electrodes having positive active material deposited thereon, the deposited active material paste composition consisting of from 23 to 57 parts by weight of liquids per 100 parts by weight of the lead content of the active material and from 0.01 to 1.0 parts by weight of silica calculated as SiO 2 per 100 parts by weight of active material (calculated as PbO 2 ) and the support of the negative electrode or electrodes having negative active material deposited thereon, the deposited negative active material being formed from a negative paste active material composition which includes at least 0.1% by weight of lignin derived lignosulphonate material, and in which the capacity of the negative electrodes is arranged to be at least as great as the capacity of the positive electrodes, the thickness of the electrodes is less than 3 mm, the thickness of the separator is in the range of 10% to 200% of the thickness of the electrodes and the volume, E, of electrolyte in the cell in relation to the sum of the pore volume of the separators, X, and the pore volume of the positive and negative active materials, Y, is not greater than 2X + Y.