Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/34—Gastight accumulators
  • H01M10/342—Gastight lead accumulators
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries

Definitions

• the present invention relates to lead acid elec ⁇ tric storage batteries, and is particularly concerned
• Recombinant lead acid batteries are known and teach the use of reduced amounts of electrolyte.
• the present invention is based on the discovery that surprisingly gas recombination can be achieved at defined high degrees of saturation and this produces
• the invention can be used with a range of battery types including automotive batteries, aircraf
• batteries and electric storage batteries suitable for providing, in"body portable form, the power needs of an individual, for example to power a miner's cap lamp.
• the invention although described with reference to batteries, is not restricted to batteries but is also applicable to single cells e.g. spirally wound cells, and the claims to batteries thus include single cells within their scope.
• a recombinant lead acid electric storage battery in which the positive and negative electrodes are separated by separators of
• electrolyte and gas permeable compressible fibrous material having an electrolyte absorption ratio of at least 100%, the volume E of electrolyte in the battery after formation being at least 0.8 (X+Y), where X is the total pore volume of the separators in the dry
• state and Y is the total pore volume of the active electrode material in the dry fully charged state, the battery at least when fully charged having substantially no free unabsorbed electrolyte, whereby substantial oxy ⁇ gen gas recombination occurs in the battery at charging
• the current conducting elements may be made of pure lead or lead calcium or lead-calcium-tin alloys or pre ⁇ ferably any other material which can provide a strong self-supporting readily handled and pasted electrode.
• one of the electrode groups and preferably the positive electrodes preferably consist of anti onial lead alloy containing at least 1.0% by weight antimony.
• the antimonial alloy may contain up to 12% by
• antimony but desirably contains 1 to 6% by weight e.g. 1% to 4% by weight, since the latter range achieves gas recombination whilst economising on expen ⁇ sive antimony.
• the material can be more
• OMPI readily cast and is more resistant to grid growth.
• the antimony content can be as low as 1% it is preferably in excess of this in order to achieve good hardness and pastability within reasonable periods
• the antimony content may be as high as 3% it is preferably less than 3% so as to keep the tendency of the plates to gas to a relatively low level as compared with the gassing tendency observed in flooded systems for such higher
• antimony contents 1.01% to 2.99% e.g. 1.1 to 2.9 to 1.2 to 2.8% by weight antimony.
• the current conducting elements of only the positive electrodes are made from a lead antimony
• alloy and the negative is a lead-calcium-tin alloy or a lead-calcium alloy or other mechanically strong alloy or grid material adapted to produce a strong self supporting readily handled and pasted electrode or pure lead though this material being soft can introduce
• Another preferred antimonial alloy for use in the present invention contains 2.3 to 2.8% antimony, 0 to 0.5% by weight arsenic e.g. 0.2 to 0.49% or 0.25 to
• OMPI is 2.3 to 2.8% by weight antimony, 0.25 to 0.35% by weight arsenic, 0.10 to.0.14% by weight tin, 0.02 to 0.05% by weight copper, 0.002% to 0.005% by weight selenium, balance substantially lead. 5.
• the charging rate is desirablykept at not greater than C/15 and preferably less than C/20 e.g. C/20 to C/60.
• the volume of electrolyte is desirably in the range 0.8 (X+Y) to 0.99 (X+Y) and especially at least 10. 0.9 (X+Y) or even at least 0.95 (X+Y). These values enable the active material to be utilized more efficiently • than when lower amounts of electrolyte are used.
• the ratio of X to Y may be in the range 6:1 to 20. 1:1 e.g. 5.5:1 to 1.5:1 or more peferably 4:1 to 1.5:1. .
• the electrolyte active material ratio is at least 0.05 e.g. at least 0.06 or at least 0.10 and is the ratio of H-S0 ⁇ in grams to the lead in the active material on the positive and negative electrodes cal- 25. culated as grams of lead.
• the ratio of negative to positive active material on the basis of the weight of active material calculated as lead may be in the range 0.5:1 to 1.5:1 e.g. 0.6:1 to 1.4:1.
• ratios below 1:1 is contrary to what is conventional in recombinant batteries but we find that recombinant operation can be achieved at
• ratios and they have the advantage of providing more positive active material for the same cell volume.
• the separator material is a
• compressible absorbent fibrous material having an electrolyte absorption ratio of at least 100% e.g. 100 to 200% especially 110 to 170%. It is electrically non-conducting and electrolyte-resistant.
• Electrolyte absorption ratio is the ratio, as a
• aqueous sulphuric acid electrolyte of 1.270 SG con ⁇ taining 0.01% by weight sodium lauryl sulphonate with 1 cm of the lower end of the strip immersed in the electrolyte after a steady state wicking condition has been reached at 20°C at a relative humidity of less
• the thickness of the separator material is measured with a micrometer at a loading of 10 kilo- pascals (1.45 psi) and a foot area of 200 square • millimetres (in accordance with the method of British standard specification No. 3983).
• the dry volume of the test sample is measured by multiplying the width and length of the sample by its thickness measured as described.
• the separator material should have a wicking height of at least 5 cms on the above test, namely that the electrolyte should have risen to a height of at least 5 cms above the surface of the electrolyte into which the -strip of separator material
• the weight to fibre density ratio namely the ratio of the weightof the fibrous material
• Recombinant lead acid batteries in which gas re ⁇ combination is used to eliminate maintenance during use
• negative active material enables the negative electrode to effect recombination of the oxygen produced by the positive electrode even at the beginning of the charge cycle. Thus it may not be necessary to have an excess weight of negative active material compared to the
• the electrochemical efficiency of the negative electrodes is in general greater than that.of the positive electrodes but it must be born in mind that the efficiency of the negative electrodes drops more
• a separator desirably having a high electrolyte absorption ratio ' as also described and defined above, which is compressible, so as to conform closely to the surfaces of the electrodes, and which has wicking or capillary activity, whereby transmission of elec-
• the container of the battery is thus provided with gas venting means.
• the gas venting means preferably take the form of a non-return valve so that air cannot obtain access to the interior of the battery although excess gas generated therein can escape to
• the lid of the container may be formed with filling apertures to permit electrolyte to be introduced into each cell.
• the filling apertures may be closed after the electrolyte has been added but the closures should
• Figure 1 is a partly cut-away perspective view of
• ____ OMPI a battery designed for use as a miner's cap lamp battery
• Figure 2 is an electron scanning photomicrograph of a preferred separator material at 1000 fold magnifi ⁇ cation.
• Figure 3 is a view similar to Figure 4 at 4000 fold magnification.
• Example 1 (miner's cap lamp battery)
• the battery shown in Figure 1 has a rated capacity of 16 Ahr and is designed for use as a miner's cap lamp
• battery It has two cells accommodated in a container 2 made as a single moulding of a polycarbonate plastics material and separated from one another by an integral inter-cell partition 4. The two cells are sealed by a common inner lid 6 which is connected to the walls of
• Each cell contains three positive plates 10 inter ⁇ leaved with four negative plates 12 separated from one .
• a sheet of separator 14 is also wrapped right around the sides of the electrode pack. There are thus eight thicknesses of the double layer separator and one double layer wrapping in each cell. The posi-
• tive plates 10 are 2.1 mms thick, 5.5 cms wide and 13 cms high and are formed from a cast grid of lead alloy and carry positive and negative active electrode material respectively. Each positive grid weighs 38 grams and each negative grid weighs 33 grams.
• the grid alloy composition in % by weight is 2.43% antimony, 0.22% arsenic, 0.04% tin, 0.006%- copper, 0.004% selenium, balance lead.
• the positive active material had the following composition before being electrolytically formed:
• the negative active material had the following
• composition before being electrolytically formed grey oxide 1080 parts, fibre 0.225 parts, barium sulphate 5.4 parts, carbon black 1.8 parts, stearic acid 0.54 parts, Vanisperse CB (a lignosulphonate) 3.27 parts, water 120 parts, 1.40 SG aqueous sulphuric
• Vanisperse CB is described in British patent specification No. 1,396,308.
• Each positive grid carries 50 grams of active
• Each negative grid carries 45 grams of active material on a dry weight basis.
• the separators 14 are of highly absorbent blotting paper-like short staple fibre glass matting about 1.2 mm
• a double layer of separator is used between the
• Each 1.2 mm sheet of separator 14 weighs 200 grams/square metre and has a porosity of 90 to 95% as measured by mercury intrusion penetrometry.
• Each sheet of separator material is 0.12 cms thick, 6.1 cms wide and 14.1 cms high.
• the total volume of separator for each cell before assembly into the cell is thus 173.1 cubic
• the weight of separator present in each cell is 31.6 grams.
• the separators being compressible conform closely to the surfaces of the plates thus facilitating elec ⁇ trolyte transfer and ionic conduction between the
• each separator should desirably be. no thinner than.about 0.6 mms since below this value we have found that growth of dendrites through the separator is liable to occur with the
• the separator weight to fiber density ' ratio is preferably 70 to 160 or 200.
• - JRE ⁇ material based on the weight of the positive active material (20% as lead) or a ratio of negative to positive active material (on a lead weight basis) of 1.20:1.
• the total weight of the grids is 246 grams.
• the true volume of the positive active material is 160.5 divided by 9 i.e. 17.8 ccs and its apparent volume is 160.5 divided by 4.2 i.e. 38.2 ccs; the void volume of the' positive active material is thus 20.4 ccs.
• material is 167.4 divided by 10.5 i.e. 15.9 ccs and its apparent volume is 167.4 divided by 4.4. i.e. 38.0 ccs.
• the pore volume of the negative active material is thus 22.1 ccs.
• the total pore volume of - the active material is 42.5 ccs, which is the value of
• the active material has sulphuric acid added to it its porosity decreases.
• the active material When the active material is charged its porosity increases and in the fully
• the calculated true surface area for the positive active material is 160.5 x 2.5 i.e. 401.3 square metres and for the negative is 167.4 x 0.45 i.e. 75.3 square
• Each dry electrolytically unformed cell is evac ⁇ uated to ahigh vacuum and has 200 ml i.e. 1.10 (X+Y) to
• the cell is then allowed to cool to 40°C (about 1 to 2 hours) and then electrolytically formed and about 5. 30 cc of water is electrolysed off, the specific gravity of the electrolyte thus rising.
• the electrolytic forming regime comprises 48 hours at 2.0 -amps, i.e. 5 C/20 Ahrs.
• the battery in the fully charged condition con ⁇ tains 0.61 grams of H»S0 ⁇ per gram of lead in the posi ⁇ tive active material and 0.55 grams of H-SO ⁇ per gram of lead in the negative active material.
• the electro- 15. lyte active material ratio was thus 0.29.
• the battery had a capacity at 1.0 amps of 15 Ahr.
• the positive and negative plates are inter ⁇ connected by respective positive and negative group bars 16 and 18. Integral with the negative group bar 20. in the left hand cell as shown in Figure 1 is a laterally projecting portion which terminates in a "flag" or upstanding portion 20 which is adjacent to the inter-cell partition 4 and overlies a hole ' 22 in the partition.
• the positive flag in the ' left hand 25. cell is connected to the similar negative flag in the right hand cell through the hole 22 so as to form an intercell connection.
• the negative group bar in the left hand cell and the positive group bar in the right hand cell are also 30. each provided with a flag 24 overlying a hole in the
• Each of the flags 24 is connected to a lug 26 outside the wall of the container but within a space defined by the outer lid 8.
• the lugs 26 are connected to a respective connecting wire of a
• the cell or each cell of a battery is normally sealed,- that is to say-that during normal operation a cell does not communicate with the atmosphere.
• Each cell is provided with a Bunsen type vent valve.
• Each valve comprises a passage 36 communi ⁇ cating with the interior of the cell and leading to the space between the internal and external lids 6
• Each passage 36 is within a boss in a respect ⁇ ive rescess in the internal lid, and the boss is seal- ingly covered by a resilient cap 40 having a depending skirt around the boss.
• Electrodes could be made from slit expanded sheet or be of wrought
• OMPI . v form e.g. perforated or punched sheet.
• the battery in this example has the same structure as that described in Example 1 except that it has -four positive plates and three negative plates. It has a rated capacity of 20 Ahr. Each positive
• plate is wrapped in a U-shaped sheet of separator with ' the separator enclosing the bottom of the-plate.
• a sheet of separator is also wrapped right around the sides of the electrode pack as in Example 1.
• the separator composition, volume and weight are also the same as in Example 1.
• the total geometric surface area of the positive plates in each cell is 572 square centimetres and of the negative plates is 429 square centimetres.
• the dry weight of active material of the positive plates is 200 x 1-07 i.e. 214 grams (as PbO i.e. 185 grams
• the true volume of the negative active material is 126 x 9 i.e. 14 ccs and its apparent volume is 126 T 4.4 i.e. 28.6 ccs; the pore volume of the nega ⁇ tive active material is thus 14.6 ccs.
• the total pore 10. volume of the active material is 43.7 ccs, which is the value of Y.
• the ratio of X to Y is thus 3.2:1 to 3.4:1. ⁇ X+Y) is 183.7 to 191.7.
• the calculated true surface area for the positive active material is 214 x 2.5 i.e. 535 square metres and 15. for the negative is 126 x 0.45 i.e. 56.7 square metres.
• Each dry electrolytically unformed cell was evacuated to a high vacuum and had 200 ml i.e. 1.09 (X+Y) to 1.04 (X+Y) of 1.27 SG aqueous sulphuric acid i.e. 91 g & rams of H Paul2S04., added to the unformed cell.
• the cells were then formed as described for Example 1.
• the battery in the fully charged condition con ⁇ tains 0.46 grams of HdonS0 ⁇ per gram of lead in the positive active material and 0.72 grams of HdonS0 per gram of lead in the negative active material.
• the cell in this example has a rated capacity of 25 Ahr at 25 amps i.e. the 1 hr rate and is designed
• the cell is accommo ⁇ dated in a container made as a single moulding of a polystyrene plastics material.
• the cell is sealed by a. lid which is connected to the walls of the con ⁇ tainer by cementing with a ' n appropriate conventional
• the cell is provided with a vent of the type described for Example 1 and the terminal posts are sealed into the end walls of the container as is con ⁇ ventional for flooded aircraft batteries.
• the cell contains six positive plates interleaved with seven
• the grid alloy composition is 6% by weight anti- . mony, balance substantially lead.
• the positive active material had the following composition, before being electrolytically formed: grey oxide 1080 parts, fibre 0.45 parts, water 140 parts, 1.400 SG aqueous sulphuric acid 76 parts.
• the negative active material had the following composition, before being electrolytically formed: grey ox de .1080 parts, fibre 0.255 parts, barium sulphate 5.4 parts, carbon ' black 1.8 parts, stearic
• Each negative grid carried 49.5 grams of active material on a dry weight basis (62 grams of wet paste).
• the plates were dry charged before assembly into the cell by immersion as pairs of positives altern ⁇ ating with pairs of negatives, the pairs being spaced
• volume of separator in the cell before assembly is thus 7 x 0.12 x 8.8 x 31.3 i.e. 231 ccs.
• the separa ⁇ tor in the cell is compressed by 5% and thus the volume of the separator in the cell is 219.4 ccs. Since the porosity of the separator is 90-95% the
• the total geometric surface area of the positive plates in the cell is 1435.5 square centimetres and of
• the true volume of the positive active material is 274 T 9 i.e. 30.4 ccs and its apparent volume is 274 f 4.2 i.e. 65.2 ccs; the- pore volume of the posi ⁇ tive active material is thus 34.8 ccs.
• the calculated true surface area for the positive active material is 274 x 2.5 i.e. 685 square metres and for the negatives is 346.5 x 0.45 i.e. 156 square metres.
• Each dry charged cell was evacuated to a high vacuum and had 300 ml i.e. 1.08 (X+Y) to 1.09 (X+Y) of 1.30 SG aqueous sulphuric acid i.e. 156 grams of H ⁇ O ⁇ added to it.
• the cell was then given 30 more cycles as in the first 25 cycles after which it had lost a further 1.7 ccs of water. On a Faradaic basis one would have expected the ' cell to have lost 110 ml over this
• the positive and negative plates are 1.27 mms thick 15.0 cms wide and 10.7 cms high and are-held in intimate contact with the separators by solid poly ⁇ propylene packing pieces. Both faces of all plates
• OMPI negative is 1.2 mms thick.
• Each sheet of the three sheets of interplate separator material is 1.2 mms thick by 23 cms by 16 cms.
• Each of the two sheets of end separator is 0.6
• the porosity is 90-95%
• the separator void volume is 125 to 132 ccs (this is the value of X).
• the weight of the separator present in each cell is 25.8 grams.
• the true volume of the positive active material is 240.8 •_ ⁇ 9 i.e. 26.8 ccs and its apparent volume is 240.8 r 4.2 i.e. 57.3 ccs the void volume of the positive active material is thus 30.5 ccs.
• the calculated true surface area for the- posi ⁇ tive active material is 240.8 x 2.5 i.e. 602 square metres and for the negative is 275.3 x 0.45 i.e. 124 square metres, using a factor of 0.45 square metre/
• the electrolytic forming regime comprised 72 hours at 1.67 amps i.e. 5 C_ Q Ahrs; the C_ Q capacity being 24 Ahr.
• the amount of electrolyte remaining is thus 1.15 10. (X+Y) to 1.11 (X+Y) and would thus appear by calcu ⁇ lation to exceed the pore volume of the system in the fully charged state.
• Example 7 was repeated except that the negative grids were made of the same antimonial alloy as the positive grid. 20. ' Example 9
• Example 7 was repeated except that the positive grid was made of an alloy of 6% by weigh antimony, balance substantially lead.
• Example 9 was repeated except that the negative grids were made of the same 6% antimonial alloy as the positive grids.
• Example 12 Gas recombination as good as for the cell of 10. Example 5 was obtained. Example 12
• the invention is applicable to recombinant lead acid electric storage batteries and cells.

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• 1980
  • 1980-05-08 IN IN543/CAL/80A patent/IN152628B/en unknown
  • 1980-05-08 EP EP80900778A patent/EP0046749A1/de not_active Withdrawn
  • 1980-05-08 WO PCT/GB1980/000082 patent/WO1980002472A1/en unknown
  • 1980-05-09 ES ES491331A patent/ES491331A0/es active Granted
• 1984
  • 1984-05-03 SG SG34384A patent/SG34384G/en unknown

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