FR2573921A1 - SEPARATOR FOR BATTERY - Google Patents

Abstract

SEPARATOR FOR BATTERY, POLYMER AND MICROPOREOUS, FOR EXAMPLE IN RUBBER, WITH REDUCED ELECTRICAL RESISTANCE THANKS TO A REINFORCEMENT BY A SILICE CHARGE CONSTITUTED OF AGGLOMERATES OF PRECIPITATED SILICEOUS PARTICLES SPHERICAL ESSENTIALLY HOLLOW. THE SILICEOUS LOAD IS CHARACTERIZED BY A SPECIFIC AREA OF 50 TO 250MG, A MAIN GRANULOMETRY OF HOLLOW SPHERICAL PARTICLES OF 0.005 TO 5.0MM AND AN OIL ABSORPTION OF 150 TO 300G 100 G OF SILICEOUS CHARGE, THE CHARGE CAN BE PREPARED BY PRECIPITATION 'A SILICEOUS PIGMENT ON A FINALLY DIVIDED WATER INSOLUBLE INORGANIC SALT, FOR EXAMPLE CALCIUM CARBONATE, THEN REMOVING THE INSOLUBLE INORGANIC SALT, FOR EXAMPLE BY LEACHING WITH AN ACID SUCH AS CHLORHYDRIC ACID. THE INVENTION FINDS ITS MAIN APPLICATION AS A SEPARATOR FOR A CAR BATTERY.

Description

l

  The present invention relates to a separator for

  terie, containing a siliceous charge. In commonly used electric storage batteries, such as the well-known 12-volt battery used in automobiles, separators are placed between the battery plates of opposite polarity to prevent the two plates from touching each other. one another by creating an electrical short circuit. Typically, the separator is a microporous article made from

  of a polymeric material, such as for example a rubber -

  natural or synthetic, or a polyolefin. The sepa-

  The size of the microporous separator should be as small as possible, as this can reduce the risk that active materials will not be absorbed.

  through the separator, thereby creating a short

electrical circuit.

  Similarly, the separator must have a low resistance

  electric, to increase to a maximum value the power of

  provided by the battery. The electrical resistance can be reduced by decreasing the overall thickness of the separator, for example the thickness of the reinforcing material; however, thinner separators are more subject to

  corrosion and other physical phenomena which affect

  try the life of the separator.

  Some siliceous fillers have already been used

  to prepare microporous separators for battery.

  See, for example, US Patent No. 2,302,832, which describes

  the use of a silica hydrogel in a rubber binder

  US Patent No. 3,351,495, which describes synthetic and natural zeolites, precipitated metal silicates such as calcium silicate, and silica gels as inorganic fillers and diluents for separators of high molecular weight polyolefins, and U.S. Patent Nos. 3,696,061, 4,226,926 and 4,237,083, which disclose the use in microporous battery separators of precipitated and finely divided amorphous silica, such as pigment.

Silicus Hi-Sil 233.

  Typically, an amorphous precipitated silica pigment is used to create a porosity in the polymeric material used to form the separator.

  for battery. This siliceous pigment has a strong

  see of absorption, and it can absorb a very large

  quantity of an aqueous or organic liquid, while

  its free flow property. In practice, the amorphous precipitated silica is charged with liquid and then mixed with the polymer material. The liquid absorbed by the silica-type filler is then removed to confer

from the porosity to the polymer.

  It has now been discovered that certain sili-

  These precipitators made it possible to produce battery separators with reduced electrical resistance compared with separators prepared with amorphous precipitated silica pigments.

  Hi-SilG 233 mentioned above. According to the present invention

  A silica pigment consisting of agglomerates of precipitated and spherical siliceous particles, substantially hollow, is used to prepare microporous polymer battery separators. This siliceous pigment is generally characterized by a specific surface area

  between about 50 and 250 square meters per gram, a di-

  measuring substantially hollow spherical particles in the range of 0.005 to 5.0 microns, and oil absorption of about 150 to 300 milliliters per hundred grams of siliceous charge. The siliceous filler is distinguished from the conventional precipitated silica pigment described, for example, in US Pat. No. 4,226,926 by the spherical and essentially hollow nature of the final particles of the pigment. The siliceous pigment mentioned above can be prepared by the process described in US Pat.

3,129,134.

  According to the present invention, it is used to produce polymeric, microporous, renfilled, battery separators of from about 10 to about 90% by weight, based on the polymeric material, of a substantially hollow spherical siliceous pigment. More particularly, between about 20 and 75, for example between

  and 60% by weight of the siliceous pigment.

  This siliceous pigment consists of agglomerates of essentially hollow spherical particles having a hollow particle diameter substantially between 0.005 and 5.0 micrometers, for example between 0.01 and 1.0 gm, or between 0.01 and 0.20 gm. The siliceous filler is further characterized by a specific surface area between

  about 50 and 250 square meters per gram, more specifically

  preferably between 75 and 200 m 2 / g, and an oil absorption of about 150 to 300, 6 to about 300, or from 230 to 270 milliliters of oil per 100 g of siliceous filler. The specific surface area of the pigment can be determined by the method of Brunauer, Emmett and Teller, J. Am. Chem. Soc. , 60, 309 (1938). This

  method, often called the BET method, measures the specific area

  absolute value of a substance by measuring the amount of a gas adsorbed under particular conditions of

  low temperature and low pressure. The specific areas

  BET examples given in the examples were obtained using nitrogen as adsorbed gas and temperatures

  corresponding to liquid nitrogen (-196 C), and under a

  relative value of 0.2. Oil absorption is the volume of dibutyl phthalate oil required to wet the pigment. The corresponding values can be

  obtained by the method described in ASTM D2414-65.

  The siliceous pigment mentioned above can be prepared by the process described in US Pat.

  3 129 134. According to the process described in the patent

  above, the pigment is obtained by precipitation of a water-insoluble siliceous product from an aqueous solution of silica in the presence of finely divided particles of a mineral salt insoluble in water, for example calcium carbonate. , and in particular of mineral salts of acids whose anhydride is normally

  gaseous, for example the mineral salts of carbon dioxide

  Picnic. The water-insoluble mineral salt is then substantially completely removed from the resulting insoluble siliceous precipitate by treating the precipitate with an acid, for example hydrochloric acid. This treatment converts the cation of the insoluble mineral salt into a

  soluble salt of the acid used for the treatment of

  and releases the anion of the salt as a gas.

  Thus, the treatment of solid calcium carbonate, in

  the suspension of the silica product with chloroacid

  Hydrogen chloride gives calcium chloride as salt

  soluble and carbon dioxide (carbon dioxide).

  More particularly, the siliceous pigments described above are prepared by precipitation of a siliceous product in a slurry of a finely divided water insoluble carbonate salt, most preferably calcium carbonate. The particle size of the calcium carbonate or other similar water-insoluble salt of the carbonic acid in the suspension should preferably be very close to the particle size of the desired hollow spherical particles of the precipitated siliceous pigment which is

  wants to use to prepare the battery separator.

  Calcium carbonate may be prepared in advance and suspended in the aqueous medium in which precipitation takes place. Alternatively, the calcium carbonate may be prepared in situ by the reaction of calcium chloride on sodium carbonate in the aqueous medium in which precipitation takes place. Products obtained by using insoluble carbonate salts formed in

  in the reactor are generally granular

  hollow spherical particle metrics lower than those obtained using carbonate salt suspensions

  insoluble in water prepared in advance.

  Given the physical aspect of the pigment, that is,

  the almost complete absence of water-insoluble siliceous materials in the core of the particles, the above process is clearly precipitating a water insoluble siliceous material on the surface of the finely divided water-insoluble carbonate salts. for example calcium carbonate particles. These

  carbonate particles are then converted, for example

  by an acid treatment, in solid constituents

  in water, leaving a silica particle

spherical practically hollow.

  The process of precipitating the material

  siliceous insoluble in water from the solution ,.

  described in US Pat. No. 3,129,134, may comprise a partial neutralization, with hydrochloric acid (or a similar neutralization agent), of the aqueous solution of the alkali metal silicate, for example sodium. This partial neutralization goes until

  the resulting aqueous solution causes, after

  time, however, after a very short time), precipitation of the water-insoluble siliceous material from the solution. Before creating this siliceous precipitate, it is possible to precipitate the siliceous pigment material by introducing into the solution a precipitate creating a soluble mineral metal salt,

  such as calcium chloride and / or sodium chloride.

  The essentially hollow spherical siliceous pigment (after removal of mineral salt - insoluble in water) is a flocculated, finely divided amorphous precipitated siliceous pigment. The pigment is in the form of flakes or agglomerates of very small particles of the siliceous material. The particle size of the spherical particles, in average number, is less than about 0.5 gm, without

  usually less than 0.3 Dm but rarely

  less than 0.01 gm. Many of these small particles are agglomerated to each other, without completely losing their individual identity, giving the pigment a flocculated state. The flakes can be larger than 40 gm, this size being measured by

their largest dimension.

  When the pigment is subjected to a mechanical action, for example grinding, the degree of persistence of these flakes can be seen to vary, that is to say the extent to which they are not degraded into smaller flakes. However, even pigments whose mean flake size has been mechanically modified still retain their flocculant characteristic. This flocculated state is essentially in the form of three-dimensional tufts, much like a cluster of small

  individual hollow spheres, the flocon particles cor-

  corresponding to the individual hollow grains, the flake itself

being represented by the cluster.

  An important feature of these precipitated siliceous pigments is the final particles. These particles consist of an optically dense outer shell (such as a shell) of a siliceous material. The internal volume surrounded by this shell has a much lower optical density, for example less than the optical density of the precipitated silica material insoluble in water, under the high magnification of an electron microscope. The final particles are almost in the form of bubbles and spheroidal volumes, the difference in optical density between the inner volumes

  and the external volumes giving them the appearance of parti-

hollow cules.

  The internal volume of the spherical particles, whose dimensions are defined by the inner surface of the siliceous shell of each particle, can be occupied

  by fluids, for example gases or liquids.

  After a good drying, the quantity of liquid, for example water, which occupies or fills the interior volume, is low, if not zero. In a representative manner, the siliceous shell surrounds or completely confines the optically less dense interior volume. However, the shell is sufficiently porous to allow removal of the insoluble carbonate salt in the water. In other words, the shell is essentially continuous (but porous), at least to the extent that, when the internal volume is a fluid, it is possible to eliminate or replace the fluid. The

  larger particles may have a hull discon-

  continued because of the non-uniform coating of the carbonate salt particles, or the coating of aggregates of carbonate salt particles, i.e. non-dispersed individual carbonate particles. The porosity of the hull is thought to consist of indirect paths from the outer side to the inner side of the hull, bypassing the final particles of the siliceous material.

which constitutes the hull.

  From a chemical point of view, the siliceous pigments have

  a very high content of SiO2, and usually contain

  at least 50% by weight of SiO2, on an anhydrous basis.

  Likewise, one or more metals are frequently found, usually in the form of their oxide, and frequently an alkaline earth metal oxide, such as calcium oxide. The spherical and hollow precipitated particles preferably contain less than 2% by weight of alkaline earth metal (the percentage being measured on the oxide) for use in battery separators. Of

  preferably, the alkaline earth metal content is lower than

  than 1% by weight, it is more particularly

  less than 0.5% by weight and especially less than

  0.1% by weight. The content of the silicone pigment can be reduced

  those made of alkaline earth metal by treating the pigment

  with enough acid to convert all of the alkaline earth metal to a soluble salt, and then wash the pigment well (after

  acid treatment and before drying).

  After drying, the siliceous pigment is white,

  downy, powdery and dry to the touch. Although it appears

  When dry, the pigment normally contains water,

  for example between about 2 and 8% by weight of "free water".

  Free water is water removed from the pigment by heating at C for 24 hours. The pigment also contains "bound water", which refers to the water removed by heating the pigment to the ignition temperature.

  that is to say between 1000 and 1200 C, for a period of time

  along, for example 24 hours. The bound water may be between about 2 and 6% of the pigment. The polymeric material in which the siliceous pigment is incorporated to make the battery microporous separator may be any of the natural and synthetic polymeric materials traditionally used to make battery separators. Among

  these materials include natural rubber, -

  styrene-butadiene rubber, nitrile rubber

  butadiene, polyisoprene, molecular weight olefins

  like polyethylene, polypropylene, poly-

  butene, copolymers of ethylene and propylene, copolymers of ethylene and butene, copolymers of propylene and butene, copolymers of ethylene, propylene and butene, polyvinyl chloride and

  copolymers of vinyl chloride and vinyl acetate.

  Mixtures of these materials have also been used to

  make separators for battery.

  Other classic products.,. polymers, such as plasticizers, antioxidants, wetting agents, carbon black and vulcanizing aids, for example sulfur for rubber-like polymeric materials can also be

  added to the composition used to make the separa-

battery charger.

  Battery separators comprising the hollow spherical siliceous charge described above

  can be prepared according to known techniques

  so much to make articles of this kind. A representative technique for making a battery separator using a vulcanizable rubber is

  US Pat. No. 4,226,926. In the above-mentioned patent,

  above, the siliceous charge is rehydrated to a: .-

  between 65 and 75% by mixing the siliceous filler with water. The free-flowing, rehydrated silica powder is mixed with the polymeric material, for example in a Banbury mixer. Then the mixture (including any additional additives required to cure the polymer particle) is rolled on a two-roll laminate to give a rolled sheet. The laminated sheet is immersed in hot water and then calendered to make the contours. Optionally, a hot, reinforcing support may be added to the laminated sheet. For example paper, or a layer of collagen / paper

  calendered is then cut to the desired dimensions.

  Another analogous procedure is described in US Pat. No. 3,351,495. In the above patent, the polymeric material, for example a polyolefin having a molecular weight of at least 300,000, is mixed with the inert filler, for example silica, and a plasticizer. The

  mixture, which may also contain stabilizers and

  conventional oxidizers, is molded or shaped, to obtain sheets, for example by extrusion, calendering, injection molding or compression. The plasticizer and / or the filler is removed from the sheet by immersion of the latter in a suitable solvent, for example chlorinated hydrocarbons for a plasticizer based on petroleum oil, and water, ethanol, acetone, etc.,

  for a plasticizer based on polyethylene glycol.

  The invention will be better understood with regard to the examples

  hereinafter given purely for illustrative purposes.

Example I

  0.5 liter per minute in a branch of a T-tube was charged with 15 liters of an aqueous sodium silicate solution Na 2 O (SiO 2) 3, 18 containing 20 g per liter of Na 2 O. The other branch of the tube was introduced into T liters of an aqueous solution of hydrochloric acid containing 11.8 grams per liter of HCl, at a rate of 0.5

  liter per minute. The partial sodium silicate solution

  Acidified acid has been introduced into the upper part of a suitable reactor. By means of an introduction tube, 15 liters of a salt solution containing 0.48 moles per liter of water were simultaneously passed through the upper part of the reactor, at a rate of 0.5 liters per minute. calcium chloride and 0.37 moles per liter of sodium chloride. The reactor was also introduced into the reactor, through an introduction tube very close to the tube for introducing the salt solution, and at a rate of 0.5 liters per minute, 15 liters of an aqueous solution containing 0.16 mol. per liter of sodium carbonate. The reagents had a temperature of about 23 C. The reaction mixture collected for the first four minutes was discarded. The remaining suspension of the reaction mixture was transferred to a container lined with polyethylene. This suspension was neutralized to pH 2.0 with 1600 ml of 6N hydrochloric acid. This acidified suspension was stirred with an air stirrer for 15 minutes, and the pH of the suspension was readjusted. 7.5 minutes with 1380 ml of 2.5 N sodium hydroxide. The suspension was aged by heating at 105 ° C.

in an oven, until the next day.

  Then, the suspension was extracted from the oven and filtered. The filter cake was washed with 72 liters of distilled water to rid the cake of the chloride ion. The filter cake was broken, placed on

  stainless steel trays and dried until the next

  The pigment was extracted from the oven, re-wetted and micropulverized through a mesh screen.

  0.508 mm (0.020 inch) circular.

  An examination of the micropulverized material under an optical microscope revealed that relatively large calcium carbonate particles were still present in the product. The concentration of calcium in the product (measured

  as calcium oxide) has been shown to be

to be 4.49%.

  The product was resuspended in 10-12 liters of distilled water, and 6N hydrochloric acid sufficient to lower the pH to 2.0 was added to the suspension. The suspension was then stirred for 4 hours while maintaining the pH at 2.0. 475 ml of hydrochloric acid were added to the suspension. Then, the suspension was neutralized with 630 ml of 2.5 N sodium hydroxide to raise the pH of the suspension to 7.65. The suspension was filtered and the filter cake washed with 24 liters of distilled water. The filter cake, washed, was dried overnight in an oven at 105 ° C and then micropulvered through a 0.508 mm (0.020 inch) round mesh screen. The micropulverized product has been

  re-wetted by exposure to ambient air for a week-

  end. The product obtained was determined for its specific surface area and oil absorption and subjected to elemental X-ray analysis. The results are shown in Table I.

Example II

  At a rate of 0.5 liters per minute in a branch of a T-tube were charged 18 liters of an aqueous Na 2 O (SiO 2) 3 18 sodium silicate solution containing 10.5 g per liter of Na 2 O. In the other branch of the T-tube, at a rate of 0.5 liters per minute, 18 liters of acid were introduced

  hydrochloric acid containing 0.187 g per liter of HCl. Simultaneous-

  36 liters of water were introduced into the reactor.

  salts (calcium chloride plus sodium chloride)

  containing 57 g / liter of crushed calcium carbonate Camel-

  Wite Super, consisting of particles of about 3 m. The salt solution contained 0.169 moles per liter of calcium chloride and 0.128 moles per liter of sodium chloride. The salt suspension was introduced into the reaction zone at a rate of 1.0 liter per minute. The temperature in the reactor was about 18 C. The suspension obtained during the first 4.5 minutes was discarded, and the resulting suspension was collected. The pH of the suspension obtained, after addition of all the reagents, was 9.0. The pH of the suspension was adjusted to 2.0 with 6.0 liters of 6N hydrochloric acid. The acidified suspension was stirred for 20 minutes, then the pH was adjusted to 8.0 with 2520 ml of hydroxide. The suspension obtained was aged by heating at 105 ° C.

until the next day.

  The aged suspension was extracted, filtered under vacuum, and the filter cake was washed with 112 liters of distilled water. The filter cake was broken, and dried overnight in a 105 C oven. The dried product was remoistened and then micropulverized through a

  0.508 mm (0.020 inch) round mesh screen.

  An optical microscope examination of the milled pigment showed large particles of calcium carbonate still present in the sample. The concentration of calcium present as calcium oxide was measured and 13.3+% by weight of CaO was found. As a result, the product was resuspended in 10 to 12 liters of distilled water, and to the suspension, to reduce the pH to 2.0, 960 ml of 6N hydrochloric acid was added. The mixture was stirred for 4 hours, then 310 ml of 2.5 N sodium hydroxide was added to raise the pH of the suspension to 7.70. The neutralized suspension was filtered, and the filter cake was washed with 32 liters of distilled water. The filter cake has been broken,

  and dried overnight in a 105 C oven.

  The dried product was micropulverized through a 0.508 mm (0.020 inch) round mesh screen. The product obtained has been determined for its specific surface area and oil absorption, and has been subjected to

  elemental X-ray analysis. The results are pre-

shown in Table I.

Example III

  In a similar manner to Example I, 36 liters of an aqueous solution of sodium silicate Na 2 O (SiO 2) 3 were introduced into a branch of a T-tube at a rate of 0.5 liter per minute. , 06 containing 20 g per liter of Na2O. The other branch of the T-tube was introduced at the rate of

  0.5 liters per minute, 36 liters of hydrochloric acid

  11.8 g of HCl per liter. The concentration of the solu-

  the calcium chloride / sodium chloride salts and the sodium carbonate solution were the same as in Example I, except that 0.5 liter per minute was charged to the reactor. liters of each of the solutions. The temperature inside the reactor was about 23-24 C. The suspension obtained had a pH of 9.15. The pH of the slurry was adjusted to 2.0 using 3.9 liters of 6N hydrochloric acid, and stirred for 3 hours at this pH. Then, the acidified suspension was neutralized to pH 7.8 with 2.4 liters of 2.5 N sodium hydroxide. The neutralized suspension was aged overnight in an oven at 105 ° C, and the suspension aged was filtered and washed with 96 liters of distilled water. The washed filter cake was dried overnight in a 105 C oven. The dried product

  was rewetted at room temperature and micropul-

  (hammer mill) on an opening screen of

mesh 0.254 mm (0.01 inch).

  The product obtained was subjected to an elemen-

  X-ray and a determination of its specific surface area and oil absorption. The results are shown in Table I.

Example IV

  The procedure of Example II was repeated using 18 liters of the aqueous sodium silicate solution described in Example III. The sodium silicate solution was partially neutralized with 18 liters of hydrochloric acid containing 12.9 g per liter of HCl,

  the introduction being at a rate of 0.5 liters per minute.

  36 liters of a saline solution containing 0.65 moles per liter of decalcium chloride and 0.51 moles per liter of sodium chloride were introduced into the reactor at a rate of 1 liter per minute. The salt solution contained 0.57 moles (57 g) per liter of preformed calcium carbonate,

  average particle size 0.75 im. The temperature in the reaction

  The pH of the suspension obtained after addition of all reagents was 8.6. The pH of the suspension was adjusted to 2.0 with 4.82 liters of 6N hydrochloric acid, and the acidified suspension was stirred for 4 hours at pH 2. Then, the acidified suspension was neutralized to pH 7.8. and aged, with 1.34 liter of 2.5 N sodium hydroxide. The neutralized suspension was aged overnight at 105 ° C. and then filtered. The filter cake was washed with 128 liters of distilled water, and the washed filter cake was dried overnight in a 105 C oven. The dried product

  was rewetted at room temperature and micropulverate

  risè on a sieve of aperture 0,254 mm (0,01

  thumb). The crushed product was subjected to a physical analysis

  that and chemical. The results are presented on the

Table I.

  The product of Example III was used as a substitute

  of a traditional precipitated silica pigment in a battery separator, and was the separator

  obtained a reduction of 15 to 20% in its resistance

electricity. -

  It is clear from the above examples that different procedures and reagents can be used to prepare the hollow silica pigments described in the present invention. For example, any water-soluble alkali metal silicate that can be used serves as a source for the SiO 2 contained in the resulting final pigment. The most widely available and widely used product is sodium silicate containing 2 to 4 moles of SiO 2 per mole of Na 2 O. However, it is also possible to use other silicates, in particular potassium silicate, lithium silicate and sodium and potassium double silicate, which contain 1 to 5 moles of SiO 2

  per mole of the alkali metal oxide.

  We can also vary the salt that triggers the

  precipitation of the water insoluble siliceous material.

  It is usually preferred that the salt be a water-soluble halide, particularly a chloride, such as

TABLE I

  Example Spe- cal interval Spe- Absorption H2 0 Analysis auxrayons X,% by weight N Nilometric * oil density m m2 / g ml / 100 g Ca Cl Fe Na Al Mg

  I 0.009-0.07 133 210 3.46 0.50 0.05 0.12 0.19 0.34 <0.01

  II 0.1-5.0 80 189 4.58 1.4 0.41 0.40 0.13 0.43 0.22

  III 0.02-0.08 102 249 4.72 1.5 0.12 0.09 0.33 0.29 0.21

  IV 0.2-1.0 57 263 5.65 1.6 0.55 0.15 0.54 0.28 0.61

  * Mainly final particles + The water content was determined by measuring the weight loss of the sample

after heating to 105 C.

  N N calcium chloride. Among the salts that can be used, mention may be made of sodium chloride, barium chloride, strontium chloride, zinc chloride, calcium bromide, sodium iodide, and the metal salts soluble in water. strong acids, for example acids -2 having an ionization constant of at least 1 10, such as metal nitrates, examples of which are nitrate

  of calcium and sodium nitrate, and sulphates of

like sodium sulphate.

  As with other reagents, there is a wide range of

  the choice of the acid used to partially neutralize the aqueous solution of the alkali metal silicate. Acids such as hydrochloric acid, sulfuric acid, nitric acid, acetic acid, sulfurous acid, phosphoric acid may be mentioned.

  and carbonic acid (or their anhydrides). For the essen-

  the acidic substances whose anions do not form water-insoluble substances with the

  alkali metals under existing conditions.

  The acids or acidic substances which can be used to treat the suspension of water-insoluble precipitated siliceous material can also be varied to solubilize water-insoluble nonsilicic material, such as calcium carbonate, in water. More preferably, these acids are those which, after a reaction on the water-insoluble matter mentioned above, will give a salt soluble in the water of the cation and lead to the production of an anhydride of the anion of the water-insoluble material, for example anhydride, since the material is calcium carbonate. For this purpose, we can propose strong mineral acids like

  hydrochloric acid and nitric acid.

  Of course, the invention is not limited to the embodiments described above and shown, from which we can provide other modes and other embodiments, without departing

of the scope of the invention.

Claims (8)

claims   1. Separator for battery, consisting of a microporous polymer reinforced with a siliceous filler, characterized in that the siliceous filler comprises agglomerates of spherical particles, essentially hollow, of amorphous precipitated silica, the hollow spherical particles having essentially an included diameter. between 0.005 and 5.0 m, said siliceous filler having a specific surface area of between about 50 and 200 m 2 / g and an oil absorption   between about 150 and 300 ml per 100 g of filler.   2. Battery separator according to claim 1,   characterized by using to prepare the separator   from about 20 to about 75% by weight of silicone filler   on the basis of the polymer material.   3. The battery separator as claimed in claim 1, characterized in that the siliceous filler comprises agglomerates of spherical particles which are substantially hollow and whose main particle size is between 0.01 and 1.0 micrometre, the specific surface area of which is between 75 and 200 m 2 / g and the absorption of oil is between about 200 and 300 ml per 100 g of filler. Battery separator according to Claim 3,   characterized in that the main particle size of the particles   hollow spherical cells is between 0.01 and 0.20 micrometers, and that the oil absorption is between   approximately 230 and 270 ml / 100 g of filler.   Battery separator according to Claim 1, characterized in that the polymer material is chosen   between natural rubber, styrene rubber   butadiene, nitrile-butadiene rubber, poly-   isoprene, high molecular weight polyethylene, polypropylene, polybutene, ethylene copolymers   and propylene, polyvinyl chloride and copper   vinyl chloride and vinyl acetate polymers.   6. Battery separator according to claim 5, characterized in that to prepare the separator of about 20 to 75% by weight of the siliceous filler, on the base of the polymeric material.   7. Microporous sheet of a polymer reinforced by   a siliceous filler, having a size and a configuration   adapted to fit between the plates of a   battery and separate them, characterized in that the material   polymeric material of said sheet is selected from materials consisting essentially of rubber   natureler styrene-butadiene rubber, polyiso-   Polypropylene propene, made from high molecular weight polyethylene, of ethylene and propylene copolymers. polyvinyl chloride, said siliceous filler consisting of agglomerates of essentially hollow spherical particles of amorphous precipitated silica, the main particle size of the hollow spherical particles being between 0.01 and 1.0 μm, these particles having a specific surface area between 75 and 200 m2 / g and an oil absorption of between about 200 and 300 ml per 100 g: of charge.   8. The polymer film according to claim 7, characterized   in that from 20 to 75% by weight of siliceous filler based on db is used to prepare the polymer sheet the polymeric material.