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 electric storage batteries, and is particularly con-
• An object of the present invention is to provide such a battery having improved separator characteristics.
• separator material having an electrolyte absorption ratio of at least 100%, the volume E of electrolyte in the battery preferably 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 battery at least when fully charged having substantially no free unabsorbed electrolyte whereby substantial oxygen gas recombination occurs in
• the ratio of X to Y may be in the range 6:1 to 1:1 e.g. 5.5:1 to 1.5:1 or more preferably. -4:1 to-..1.5:1.
• the charging rate is desirably kept at- hot greater than C/15 and preferably less- han C/20 e.g.
• the volume of electrolyte is desirably in the range 0.8 (X+Y) to 0.99 (X+Y) and especially at least 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
• 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 SO. in grams to the lead in the active material on the positive and negative electrodes cal-
• OMPI / t o WIPO It is preferably in the range 0.10 to 0.60 especially 0.11 to 0.55 e.g. 0.20 to 0.50.
• the ratio of negative to positive active material may be in the range 0.5:1 5. to 1.5:1 e.g. 0.6:1 to 1.4:1.
• ratios below 1:1 is contrary to what is conventional but we find that recombinant operation can be achieved at these ratios and" hey have the advantage of providing more positive active material for the same cell volume. 10.
• the separator material is a • compressible absorbent fibrous material having an electrolyte absorption ratio of at least 100% e.g. 15. of 100 ' to 200% especially 110 to 170%. It is elee- . trically non-conducting and electrolyte resistant. Electrolyte absorption ratio is the ratio, as a percentage, of the volume of electrolyte absorbed ⁇ by the wetted portion of the separator material to 20.
• the thickness of the separator is measured with 4 .
• 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 *
• the weight to fibre density ratio namely the ratio of the weight of the fibrous material in grams/square metre to the density in grams/cubic centimetre of the material from which the individual
• fibres are made preferably being at least 20 prefer ⁇ ably at least 30 and especially at least 50.
• the elec ⁇ trolyte is an aqueous sulphuric acid electrolyte con ⁇ taining an amount of wetting agent effective to ensure
• the electrolyte wicks up the separator to a height of at least 5 cms in the above test, e.g. an amount of at least 0.01% by weight of sodium lauryl sulphonate, and the separator has thermoplastic
• organic polymer fibres of diameters in the range up to 10 microns e.g. in the range 1 to 6 microns and the average of the diameters of the fibres is less than 10 microns e.g. 1 to 6 microns especially 1 to 4 microns.
• Recombinant lead acid batteries in which gas recombination is used to eliminate maintenance during
• the battery operates under the so-called "oxygen cycle".
• oxygen generated, during charging or overcharging, at the positive is trans ⁇ ported, it is believed, through the gas phase in the separator to the surface of the negative which is
• the higher electrochemical efficiency of the negative active material enables the negative elec ⁇ trode 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
• one desirably provides that, under the charge and discharge conditions, under which the battery is designed to operate, the capacity of the negative electrodes in each cell will normally, and desirably always, be-in excess of that of the posi-
• the charging conditions generate oxygen at a faster rate than it can be transported to the negative and react thereat, then the excess oxygen is vented from the battery.
• 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
• the lid of the container may be formed with filling apertures to permit electrolyte to be intro ⁇ quizd into each cell.
• the filling apertures may be closed after the electrolyte has been added but the
• closures should provide gas venting means or separate gas venting means should be provided.
• the surface pore size of the separator can also be controlled, and thereby the resistance of-the separator to "treeing through", by applying a light
• the calendering at the surface of the separator reduces the porosity of the separator at that surface
• the overall reduction in thick ⁇ ness of the separator is preferably such that the thickness is at least 40% e.g. 70 to 90% or 99% of the
• thermoplastic organic polymer fibres may be subjected to an oxidative treatment prior to being formed into the sheet material.
• the oxidative process can consist of or include
• agent can be used in conjunction with the other agents, Gas phase chemical treatments e.g. by corona dis ⁇ charge, or with ozone or ultraviolet light can also be used to increase the wettability of the fibres.
• the wettability of the polymeric fibres can also be • used, for example gas phase exposure to halogens and sulphur dioxide, carbon monoxide or carbon dioxide in sunlight or ultraviolet light or other ionizing radiation to achieve halosulphonation or halocarboxy-
• the fibres must then be sub ⁇ jected to hydrolysis and substantially complete, elimination of ions liable to interfere with the electrochemical process in the battery for example halogen ions and heavy metal ions such as chromium;
• sulphonates such as alkyl aryl sulphonates, for example, sodium dodecyl benzene sul- 5.
• phonate, or succinates such as sulphosuccinates, for example sodium dioctyl sulphosuccinates , or quaternary ammonium wetting agents such as alkyl aryl alkyl quaternary ammonium chlorides.
• quaternary ammonium wetting agents such as alkyl aryl alkyl quaternary ammonium chlorides.
• Figure 2 is an end elevation on the line II-II of Figure 1;
• Figure 3 is an electron scanning photomicrograph 20., - of a preferred separator material at 200 fold magnifi ⁇ cation;
• Figure 4 is a view similar to Figure 3 at 1000 fold magnification.
• Example 1 25 The battery has a capacity of 30 Ahr and has six cells accommodated in a container 2 made as a single moulding of polypropylene plastics material and separated from each other by integral intercell partitions 4. The cells are sealed by a common lid 30. 6 which is connected to the walls of the container 2
• Each cell contains four positive plates 10 inter ⁇ leaved with five negative plates 12 separated from one another by separators 14 consisting of four layers of electrolyte and gas permeable compressible
• polyester fibre mat material whose composition and function will be described below.
• a double sheet of separator 14 is also placed on both outside faces • of each cell.
• the positive plates 10 and negative plates 12 are formed from a cast grid of lead alloy
• the positive plate is 2.0 mms thick and the negative plate is 1.8 mms thick and are held in inti-
• the plates may be 1 to 2 mms e.g.
• the positive active material had the following composition before being electrolytically formed: Hardinge grey oxide 13640 parts, fibre 6 parts, water 1800 parts, 1.40 SG aqueous sulphuric acid 750 -parts.
• the paste had a density of 4.2 gr/cc.
• the negative active material had the following composition before being electrolytically formed: Hardinge oxide 13640 parts, fibre 3 parts, barium 5. sulphate 68 parts, carbon black 23 parts, stearic acid 7 parts, Vanisperse CB (a lignosulphonate) 41 parts, water 1525 parts, 1.40 SG aqueous sulphuric acid 875 parts.
• the paste had a density of -4.3. Vanisperse CB is described in British patent 10. specification No. 1,396,308.
• the active material As the active material has sulphuric acid added to it, its porosity decreases. When the active ' material is- charged its porosity increases and in the fully charged condition is about the same as it 15. is in the unformed state* before addition of electro ⁇ lyte.
• Each positive plate carried 109 grams of active material on a dry weight basis. .
• Each negative plate carried 105 grams of active 2 ⁇ . material on a dry weight basis.
• Each sheet of the ' separators 14 is a highly absorbent short staple fibre polyester matting, about 0.3 mm thick, there being fibres 61 as thin as 1 micron and fibres 60 as thick 25. as 6 microns in diameter, the average of the dia ⁇ meter of the fibres being about 2.0 microns.
• Figures 3 and 4 show this material at different magnifications, Figure 3 at 200 fold and Figure 4 at 1000 fold.
• Each sheet of the separator 14 weighs 50 grams/
• Each sheet of separator material is 0.3 mms thick and weighs 50 grams/square metre.
• the total volume of separator used for each cell is 238 cc which has a pore volume of 214 cc and a porosity of 90% before
• OMPI lead sheets having an area of 25.1 square cms immersed in the above electrolyte and allowed to soak for hour, 2 hours and 24 hours before measuring the resistance in milliohms. The values were 3.5, 1.5 and 1.0 but without
• the separators being compressible conform closely to the surfaces of the plates thus facilitating electrolyte transfer and ionic conduction between the plates via the separator.
• the total geometric surface are of the positive plates in each cell.is 767 square centimetres and of the negative plates 959 square centimetres.
• the dry weight of active material of the positive plates is 4 x 109 x 1.07 i.e. 468 grams (as Pb0 2 i.e. 405 grams
• the true density of the positive active material (Pb0_) in the fully charged state is 9 gr/cc and the true density of the negative active material (sponge lead) in the fully charge state is 10.5 gr/cc.
• 25. material is 4 x 109 -J- 9 i.e. 48.4 ccs and the true volume of the negative active material is 5 x 105 10.5 i.e. 50 ccs.
• the apparent density of the dry positive active material is 4.2 gr/cc and thus the apparent volume of the dry positive active material is 4 x 109 ⁇ 4.2 i.e. 103.8 ccs.
• the apparent density of the dry negative active material is 4.4. gr/cc and thus the apparent volume of the dry negative active material
• the pore volume of the positive active material is 55.4 ccs and of the negative active material is 69.3 ccs and the total pore volume of the dry fully charged active material is 124.7 ccs, which'
• 10. is the value of Y.
• the ratio of X to Y is 1.47:1. (X+Y) is 307.7.
• the calculated true surface area for the posi ⁇ tive active material is 1170 square metres and for the negative is 220 square metres using a factor of
• Each dry electrolytically unformed cell was evacuated to a high vacuum and had 325 ml i.e. 1.06
• the electrolytic forming regime comprised: 4 hours at 11 amps, 17 hours at 5.5 amps, 7 hours at 2.7 amps and 20 hours at 2.2 amps.
• the battery contained 0.7 ml of 1.275 SG aqueous sulphuric acid per gram of positive active material (as lead) and 0.66 ml of 1.275 SG aqueous sulphuric acid per gram of negative active material as lead.
• the battery contained 0.34 ml of 1.275 SG aqueous sulphuric acid per gram of positive and negative active material combined (as lead).
• the positive group bar in the right hand cell is provided with a flag 24.
• the flag 24 is connected to a terminal 26 in the lid of the con ⁇ tainer.
• Each cell of the battery is normally sealed,
• a relief valve is provided to exhaust the excess gas and is arranged to operate at a pressure of only 2 to 3 psi.
• valve is of the Bunsen type and comprises a passage 36 communicating with the interior of a cell and leading to the exterior of the lid.
• Each passage 36 is within a boss in a respective recess 38 in the lid, and the boss is sealingly covered by a resilient cap
• the cap 40 having a depending skirt around the boss.
• the cap 40 normally seals the passage 36, but if an excessive pressure should occur in the battery the skirt of the •cap lifts away from the boss to vent the cell.
• a disc 42 provided with a vent hole or clearance and
• the battery is an automotive starting, lighting and ignition battery and is of the same structure as that described and illustrated for Example 1. . However the battery has a capacity of 25 Ahr and each of the six cells contains 3 positive plates 10 inter-
• separators 14 consisting of 2 layers of electrolyte and gas permeable compressible polyester fibre material whose composition and function will be described below.
• the positive plates 10 and negative plates 12 formed from a cast grid of lead alloy containing 0.07% cal ⁇ cium and 0.7% tin and carry positive and negative
• the positive and negative plates are both 1.37 mms thick.
• the positive and negative active materials are the same as in Example 1.
• Each positive plate carried 76 grams of active material on a dry weight basis.
• Each negative plate carried 76 grams of active • material ona dry weight basis.
• Each sheet of the separators 14 is a highly repetitive material.
• absorbent short staple fibre polyester matting having a structure and properties as described in Example 1 but being about 0.6 mms thick.
• Each sheet of the separator 14 weighs 100 grams/ square metre and has a porosity of about 90% as
• the density of the polyester from which the fibres of the separator are made is 1.32 gr/cc; the weight to fibre density ratio is thus 78 for each sheet or 151 for the complete separator.
• Each sheet of separator material is 0.6 mms thick and weighs 100 grams/square metre.
• the total volume of separator used for each cell is 155 cc which has a pore volume of 140 cc. and a porosity of 90% before being placed in the cell.
• cell the volume of separator is 140 cc and the pore volume is 126 cc. This is the value of X.
• the weight of separator present in each cell is 25 grams.
• the total geometric surface area of the positive plates in each cell is 500 square centimetres and of
• the negative plates 667 square centimetres.
• the dry weight of active material of the positive plates is 3 x 76 x 1.07 i.e. 244 grams (as PbO i.e. 211 grams as lead) and that of the negatives is 3 x 76.x 0.93 i.e. 282 grams (as lead) an excess of 15% negative
• active material based on the weight of the positive active material (34% as lead). The total weight of the grids is 350 grams.
• the pore volume of the positive active material is 29.3 ccs and of the negative active material is
• active material is 570 square metres • and for the negative is 137 square metres using a factor 0.45 square metre/gram for the negative active material and 2.5 square metres/gram for the positive active material.
• Each dry electrolytically unformed cell was
• the electrolytic forming regime comprised: 48 hours at 2.5 amps.
• the amount of electrolyte remaining is thus 1.08 5. (X+Y) and would thus appear by calculation to exceed the pore volume of the system in the fully charged state.
• the battery contained 1.0 ml of 1.300 SG aqueous 15. sulphuric acid per gram of positive active material • (as lead) and 0.75 ml of 1.300 SG aqueous sulphuric acid per gram of negative active material as lead.
• the battery contained 0.42 ml of 1.300 SG aqueous sulphuric acid per gram of positive and negative 2.0. active material combined (as lead).
• electrode pairs could be made from slit expanded sheet or be of wrought form e.g. perforated or punched sheet or from •fibrous supports provided with * electrically conduc ⁇ tive coatings or deposited conductors such as are
• the grids are preferably 0.1 to 3.0 mms thick especially 1.5 to 2.5 mm thick.
• the preferred alloy is a lead calcium tin alloy preferably containing 0.06 to 0.13% e.g.
• Alternative 'alloys include 99.9% lead and anti- monial alloys such as those disclosed in United States patents Nos. 3879217 and 3912637.
• the invention is applicable to recombinant lead acid electric storage batteries and cells.

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• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Secondary Cells (AREA)
• Cell Separators (AREA)
• Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
• Supply Devices, Intensifiers, Converters, And Telemotors (AREA)
• Laying Of Electric Cables Or Lines Outside (AREA)

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• 1980
  • 1980-04-25 US US06/229,565 patent/US4373015A/en not_active Expired - Fee Related
  • 1980-05-08 IN IN542/CAL/80A patent/IN152678B/en unknown
  • 1980-05-08 WO PCT/GB1980/000081 patent/WO1980002471A1/en not_active Application Discontinuation
  • 1980-05-09 ES ES491330A patent/ES491330A0/es active Granted
  • 1980-05-09 ZA ZA00802794A patent/ZA802794B/xx unknown
  • 1980-11-17 EP EP80900777A patent/EP0028226A1/en not_active Withdrawn
• 1981
  • 1981-01-06 NO NO810023A patent/NO810023L/no unknown

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