Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C44/00—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles
  • B29C44/34—Auxiliary operations
  • B29C44/56—After-treatment of articles, e.g. for altering the shape
  • B29C44/5627—After-treatment of articles, e.g. for altering the shape by mechanical deformation, e.g. crushing, embossing, stretching
  • B29C44/5654—Subdividing foamed articles to obtain particular surface properties, e.g. on multiple modules
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/64—Carriers or collectors
  • H01M4/70—Carriers or collectors characterised by shape or form
  • H01M4/80—Porous plates, e.g. sintered carriers
  • H01M4/808—Foamed, spongy materials
• • 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 the manufacture of a porous foam product and an electrode made from the porous foam product.
• the porous foam product when filled with an appropriate active material, is useful as a battery electrode.
• Reticulated porous products such as a reticulated polyurethane foam, are generally made in a continuous manner in a block or log form.
• U.S. patent 5,512,222 there is disclosed a method of producing a continuous slab of polymeric foam in which a mixture of liquid foam reactants is introduced into the bottom interior portion of a trough with an open top. The foam mixture then expands upwardly in the trough.
• the blocks are then "peeled" around a core, which is oriented along a major axis of the foam, typically the x axis, i.e. , the width of the block, or around the y axis, i.e. , the length of the block.
• This method permits the largest flexibility for peeling long continuous strips in maximum width while mir ⁇ riizing waste. Peeling in this manner produces a foam with pores whose aspect ratio varies in a periodic manner from round to oval.
• the present invention pertains to making porous products including metal foams that can serve as the matrix material for battery electrodes having high current density, high capacity characteristics.
• the porous products typically in the form of metal foam sheets, can further have enhanced tensile strength and elongation, and lower resistivity. They furthermore exhibit lower longitudinal weight variation.
• the articles When filled and serving as battery electrodes, the articles can exhibit higher battery capacity, decreased variation in cell capacity, and higher voltages during high drain rates.
• the invention is directed to the method of producing a three- dimensional reticulated sheet of polymeric foam from a prepared first mass of polymeric foam, wherein the prepared first mass of polymeric foam has a y axis length, an x axis width, and a z axis height, and the polymeric foam sheet can be produced from the prepared first mass by peeling the sheet from the first mass in a plane at least substantially parallel to the y axis length, the improvement in the method of producing polymeric foam sheet comprising the steps of: establishing a second mass of foam from the prepared first mass of polymeric foam, the foam second mass retaining the x, y and z axes of the prepared first mass; shaping the foam second mass for peeling the foam in a plane at least substantially parallel to the z axis; and peeling a sheet of polymeric foam, from the shaped foam second mass in a plane at least substantially parallel to the z axis.
• the invention is directed to a method of producing an electrode for a battery, comprising the steps of: providing a foam support member, with the support member having a multitude of pores; establishing the foam support member in sheet form, having a sheet length in the longitudinal direction and a sheet width in the transverse direction, with the pores having a uniform pore aspect ratio in the longitudinal direction; coating the foam support member with an electroconductive coating; and introducing active material into the sheet form electrode support member to produce an electrode in sheet form containing the material in the sheet.
• the invention is directed to an apparatus for preparing a three-dimensional reticulated sheet of polymeric foam from a prepared first mass of polymeric foam, wherein the prepared first mass of polymeric foam has a y axis length, an x axis width, and a z axis height, and the polymeric foam sheet can be produced from the prepared first mass by peeling the sheet from the first mass in a plane at least substantially parallel to the z axis, which apparatus comprises: foam supply production means producing a polymeric foam mass having a y axis longitudinal direction; and cutting means severing the foam supply into sheet form having a length along the z axis of the foam mass.
• the invention is directed to a porous foam article, which article is a three-dimensional reticulated foam article having a substantially cylindrical outer surface, and having an x-axis radius, a y-axis radius and a z-axis height, wherein the outer surface is cylindrical around the z-axis, the article consisting of a multitude of pores, the article providing a uniform pore aspect ratio in the longitudinal direction for a sheet of foam severed from the article, wherein the sheet has longitudinal direction in the x-axis direction.
• Fig. 1A is a perspective view of a machine-produced foam mass in block form having x, y and z axes and showing the present practice of a sheet of foam, shown in phantom, peeled from the foam mass around the y axis.
• Fig. 1 is a perspective view of a prepared foam mass of substantially cylindrical form.
• Fig. 2 is a perspective view of a prepared foam mass obtained by coring of the machine-produced foam mass, which can be a mass as shown in Fig. 1A.
• Fig. 3 is a perspective view of the prepared foam mass of Fig. 2, representative of the present invention, and showing, in phantom, a sheet of foam peeled from the mass around the z axis.
• the polymeric foam produced can comprise any of a variety of stretchable foams, including organic or inorganic open-cellular materials. Synthetic or natural fiber foams, including flexible paper or wood products can also be useful.
• the substrate material is one which has open interconnected cells.
• reticulated foam shall include all such substrate materials.
• Useful reticulated polymeric foams which may be employed are any of those polymeric substrates which are conventionally used for preparing polymer foams such as polyurethanes, including a polyether-polyurethane foam or a polyester polyurethane foam; polyesters; olefin polymers, such as a polypropylene or polyethylene; vinyl and styrene polymers, and polyamides.
• polyurethanes including a polyether-polyurethane foam or a polyester polyurethane foam
• polyesters such as a polypropylene or polyethylene
• vinyl and styrene polymers such as a polypropylene or polyethylene
• vinyl and styrene polymers such as a polypropylene or polyethylene
• vinyl and styrene polymers such as a polypropylene or polyethylene
• vinyl and styrene polymers such as a polypropylene or polyethylene
• vinyl and styrene polymers such as a
• the article produced in the present invention can be referred to as a porous article sometimes referred to as a "porous product” or, for convenience, simply as a “foam".
• the porous product is preferably an open-cell three dimensional product having continuously connected strands. This may be referred to herein as a product having "open interconnected cells”.
• the porous product will usually be in sheet form, i.e., have a thickness dimension less than its width or length. More particularly, the product produced will usually be in strip form, having a thickness that is less than the product width, and a width that is less than the product length.
• the starting foam material usually referred to herein as a "machine-produced" mass of foam, or "prepared first mass” of foam, can have a length in the longitudinal direction. Additionally, the mass will have a width that may be referred to herein as a width in the transverse direction.
• the porous product in strip form provided from the first mass will be in a planar, e.g., plate-like or sheet form having broad, front and back major faces that are usually flat.
• machine-produced polymeric foams may have widths in the transverse direction on the order of 6 to 80 inches, and be produced in continuous lengths which can run as great as on the order of 1000 feet or more.
• the polymeric foam is first typically produced then as a foam mass 1 in a log, bun or loaf form, i.e., the "machine-produced foam” or "prepared first mass of foam” .
• a foam first mass prepared in this manner will have three axes, x, y, and z, conforming to width, length and height, respectively, as shown in the figure.
• the x, y, and z axes are to be understood to be at 90° angles to one another, unless otherwise stated herein.
• the foam mass 1 will contain pores 5 that can be visible on the surfaces of the foam mass 1.
• This machine-produced first mass of foam 1 is then peeled into a sheet or strips, which, in accordance with the prior art process, is generally while the prepared machine-produced mass of foam 1 is spinning around the longitudinal y-axis, as represented by the directional arrow in Fig. 1A.
• paring of the foam mass 1 may be employed to remove any rough edges and to shape the mass of foam 1 into a cylindrical shape. Spinning of the foam mass 1 in this manner may be facilitated by placement of a supporting core member (not shown) within an aperture 3 that runs through the center of the prepared machine-produced foam mass 1 in the direction of the longitudinal y-axis. The aperture 3 is thus present along the y axis center line of the foam 1.
• the aperture 3 may be cut through the first mass 1 and be positioned along the same axis around which the machine-produced first mass 1 will be spun.
• the machine-produced foam mass 1 as it comes into contact with a cutting means (not shown) such as by spinning around the core member, can provide for a peeling of the machine-produced mass of foam 1 that results in the emergence from such application of a "strip" or "sheet” of foam 10.
• the resulting strip 10 will have a length in the longitudinal or x axis direction and a width in the transverse or y axis direction.
• Production of foam strip or sheet 10 in this manner yields pores 5 in the sheet 10, some of which will be circular and some of which will be oval, with the oval pores having a long axis in the machine-produced or x axis direction of the mass 1.
• Rotation of the log clockwise, as depicted in Fig. 1A yields pore shapes 5 of circular, oval, and back to circular across the width or y axis of the strip 10.
• This variation in the machine-produced or x axis direction results in variability in properties of the foam sheet 10, as will be most particularly discussed hereinbelow in connection with the examples.
• a prepared second mass of foam 6 having "x", a "y” and “z” axes oriented in the same manner as the foam 1 of Fig. 1A.
• the x, y and z axes correspond to width, length and height, respectively.
• the x, y, and z axes are established at 90° angles to one another.
• the prepared second mass of foam 6 can be produced by cutting away at the outside of the machine-produced foam 1 (Fig. 1) so as to establish a substantially cylindrical shaped second mass of foam 6.
• Such a substantially cylindrical shaped mass of foam 6 shall be referred to herein as a "second foam mass” or "prepared foam mass”.
• the second foam mass 6 Upon shaping, the second foam mass 6 retains the three dimensional character of the machine-produced foam 1, having x, y and z axes, but having a cylinder center line in the z-axis direction.
• the second foam mass 6 may be smaller than the machine-produced foam mass 1.
• An aperture 7 can then be introduced into and through the center of the prepared foam mass 6 in a manner such that the aperture is at least substantially parallel to the z axis of the prepared foam mass 6.
• Fig. 2 there is then depicted an alternative arrangement by which the prepared foam mass 6 may be obtained in which the machine-produced foam mass 1 may be cut as by coring. Removing the second mass 6 from the first mass 1 leaves an aperture 11 in the first mass 1. Such coring occurs in a manner essentially parallel to the z-axis of the machine-produced foam 1.
• a portion of the machine-produced foam mass 1 is prepared as a substantially cylindrical, prepared foam mass 6.
• an aperture 7 can be introduced into and through the center of the prepared foam mass 6 in a manner at least substantially parallel to the z axis of the prepared foam mass 6.
• a prepared foam mass 6 in cylindrical form is positioned by securing means (not shown) such that the cylinder center line is at least essentially along the z-axis.
• the prepared foam mass 6 is then spun in a direction around the z-axis.
• the prepared foam mass 6 is engaged with means (not shown) for peeling a sheet 4 of foam from the foam mass 6.
• the means for peeling is established so as to be at least substantially parallel, and preferably completely parallel, to the z-axis.
• foam sheet 4 By this spinning and cutting action, a thin continuous layer of foam sheet 4 is peeled from the prepared foam mass 6. Such peeling occurs in a plane at least substantially parallel to the z axis. Production of foam sheet 4 in this manner yields uniform pores 5 in the sheet 4 of at least substantially circular shape. It should be noted, however, that pore shape in Fig. 3 is exaggerated for clarity.
• Such securing means may constitute a mandrel positioned through the aperture 7 of the prepared foam mass 6. Where the center aperture 7 is absent from the prepared foam mass 6, it is further contemplated that such securing means may constitute clamps positioned on a top 8 and a bottom 9 of the prepared foam mass 6 such that the prepared foam mass 6 is freely moveable in the direction of rotation around the z axis.
• top and bottom are used herein for convenience to provide a better understanding of the positioning of the securing means.
• the means for peeling of a foam mass into a sheet 4 may be any means, e.g. , a cutting means, such as may be conventional in the industry.
• the means can include a blade, knife or heated wire. It is contemplated that peeling may occur by advancement of the foam mass 6 into the cutting means. It is also contemplated that the foam mass 6 could remain stationary and the cutting means be advanced into the foam mass.
• the foam mass 6 could be spun around the z-axis, but the foam mass 6 be otherwise held in a stationary position, e.g., not advanced in a forward manner, such that a hot wire run through the foam mass 6 in a spiral manner can produce a foam sheet 4.
• a representative sheet of polymeric foam produced by the method of the present invention will be an open cell foam sheet 4 having a thickness within the range from about 0.5 mm to about 10 mm. However, depending on the battery cell type and application, this thickness will vary.
• the foam sheet 4 may have an average number of pores per inch within a wide range, typically within a range from about 10 to about 150 pores per inch (ppi). The average number of pores per inch is dictated by application. For instance, for an electrode suitable for a nickel cadmium battery, it may be desirable to utilize a polymer foam having from about 40 to about 110 ppi. Additionally, by the present invention, the pore shape of the polymeric foam product will display a uniformity in pore aspect ratio in the longitudinal direction.
• An application of the preferred porous foam sheet 4 can be where it is utilized to prepare a battery electrode.
• the precursor material may have some electrical conductivity.
• this can be achieved by employing any of a number of well-known procedures such as coating with a latex graphite; coating with a metal powder as described in U.S. Patent 3,926,671; electroless plating with a metal such as copper or nickel; sensitizing by application of a metal such as silver, nickel, aluminum, palladium or their alloy as described in U.S. Patent 4,370,214; application of a paint containing carbon powder, or a metal powder such as silver powder or copper powder; coating of a pore-former as described in U.S.
• Patent 4,517,069 and vacuum deposition of a metal by cathode sputtering with a metal or alloy as disclosed in U.S. Patent 4,882,232.
• One suitable electroless plating process is disclosed in the EPO published application 0 071 119.
• Polyurethane foams which are made conductive by coating with a latex graphite are commercially available and are marketed by Foamex International, Inc.
• U.S. Patent 5,300,165 proposes a similar method for the manufacture of metallic porous sheets from mesh sheets and non- woven fabric sheets, which can be layered together.
• the plating is often nickel plating and the resulting porous nickel sheet will generally have a weight within the range of from about 200 grams per square meter, up to about 5,000 grams per square meter, basis square meters as measured on a major face of the resulting metal foam support member. More typically, this will be a sheet weight within the range of from about 400 to about 700 grams per square meter.
• the resulting metallized article can be washed, dried, and may be thermally treated, e.g., to decompose a polymer core substance. In some instances, the article may be annealed, such as in a reducing or inert atmosphere.
• thermal decomposition U.S. Patent 4,687,553 suggests a multi-stage heat decomposition method.
• thermal decomposition is conducted at a temperature in the range of about 500°C - 800°C for up to about three hours depending on the plastic foam (polymer core substance) used, followed by annealing in an inert or reducing atmosphere at a temperature in the range of about 800°C - 1100°C.
• the active material for a negative battery electrode can be a hydrogen storage material, generally the AB 2 type hydrogen storage alloy, or an AB 5 type hydrogen storage alloy.
• A can be an element with a large affinity for hydrogen such as Zr or Ti
• B is a transition metal such as Ni, Mn, or Cr.
• Members of the AB 2 class of hydrogen-absorbing materials may also include the binary ZrCr 2 , ZrV 2 and ZrMo 2 , although all of this class of hydrogen-absorbing material are contemplated as being useful in the present invention.
• the AB 5 class of alloys can be referred to as the rare-earth (Misch metal) alloys based around lanthanum nickel.
• A can be represented by lanthanum, while B might be defined as above.
• the AB 5 type negative materials for battery negative electrodes are well known and many materials are described in the prior art. All such hydrogen storage alloys are contemplated as useful in preparing a negative electrode of the present invention.
• the negative electrode cadmium active material will comprise cadmium metal.
• any of the positive electrodes as are conventional or as are contemplated for use in a battery will be useful in the present invention.
• a positive electrode will contain a positive active material, usually composed of a metal oxide, in a support.
• a representative active material comprises nickel oxyhydroxide.
• a lithiated transition metal intercalation compound for the positive active material, there may be used.
• such material will generally be made into a paste or slurry, typically using water or an organic solvent, although it is contemplated that the use of dry, finely divided active material, may also be employed.
• the paste or slurry is then introduced into the metal foam support member 1, such as by any process for introducing a paste or slurry material into a foam type substrate, e.g., roll coating, spray application, or pressure or vacuum application.
• Electrodes in the battery can be separated with a usually synthetic, typically non- woven material.
• the separator may serve as an insulator between electrodes as well as a medium for absorbing an electrolyte, e.g., an alkali electrolyte.
• a representative separator material is a nylon or a polypropylene non- woven fabric.
• the polypropylene fabric could be of sulfonated polypropylene.
• the separator may have, for example, on the order of a 60 percent to 70 percent porosity.
• a serviceable electrolyte solution for a nickel metal hydride battery can be an aqueous potassium hydroxide solution. Such solution may contain lithium hydroxide, e.g., a 35 weight percent electrolyte solution with 1 percent LiOH.
• EXAMPLE 1 A commercially available, open cell foam in long log form having a y axis length in excess of 150 meters (m), which was grade Z-110 polyurethane foam available from Foamex International, Inc., was prepared. Several short loaves were cut from the long log and some of these loaves were peeled around the y-axis of the loaf. These sheets were coiled into roll form. Several other of the short loaves were peeled around the z-axis of the loaves to prepare sheets that were also provided in roll form. For purposes of this example, test material from the y-axis peeled loaves will be referred to as the comparative product. The test material from the z-axis peeled loaves are the invention product.
• Plated coupon samples from 90 rolls of y-axis peeled foam were weighed and found to have an average weight of 498 grams per square meter (g/m 2 ) which units in g/m 2 for this foam in sheet form are conventional in the industry. Plated coupon samples from 10 rolls of the z-axis peeled foam were weighed and found to have an average weight of 505 g/m 2 . Samples were also measured and found to have a thickness of 1.67 mm and 1.65 mm respectively .
• the samples were also evaluated for elongation.
• elongation the samples were stretched with the tensile apparatus and the elongation is the distance traveled, expressed as a percentage, at peak tensile strength.
• the longitudinal elongation was 8.02% and the transverse elongation was 11.9% . This compares with a longitudinal elongation of 6.5% and transverse elongation of 12.4% for the y-axis peeled foam, or a longitudinal elongation increase of 23%, with only a 4% decrease in transverse elongation.
• Transverse resistivity for the y-axis peeled comparative product was 0.00234 ohm/cm. This compares with a resistivity of 0.00175 ohm cm for the z-axis peeled invention product, or a resistivity improvement of 25 % .
• Resistivity results are expressed in Table 1 as a resistance ratio of transverse to longitudinal resistivity. For the comparative foam, the resistance ratio was 1.49. For the z-axis peeled foam, the resistance ratio was 1.13. A resistance ratio of 1.0 is indicative of perfectly round pores. Therefore, the data indicate that the z-axis peeled invention product has just slightly elongated pores in the longitudinal direction. Results of all testing for the comparative product as well as the invention material are presented in Table 1 below.
• z-axis peeling of the polymer foam provides for a plated foam product having greatly increased longitudinal elongation, without deleterious sacrifice in transverse elongation. Improved longitudinal elongation allows for increased loading of active material, which enables higher battery capacities.
• the invention product also has highly desirable increased longitudinal and transverse tensile strength. Additionally, the lower resistance of the invention product enables advantageous battery performance at higher drain rates.
• Example 1 There was again used a commercially available open cell foam prepared in loaf form, which was grade Z-110 polyurethane foam available from Foamex, Inc. The loaf was prepared and then three portions of the loaf were peeled. A single 300 (millimeter) mm wide roll was peeled around the x axis of one portion, the y axis of a second portion and, the z axis of the third portion. Each roll was then nickel plated and annealed as in Example 1.
• Example 2 Samples of 20 mm long x 300 mm wide strips were cut from each roll and were then weighed. Weight for each sample was determined in g/m 2 , as in Example 1. The standard deviation of the weight from 140 strips of the loaf portion peeled around the y-axis, 140 strips of the loaf portion peeled around the x-axis, and 140 strips of the loaf portion peeled from around the z-axis was determined as in Example 1. The standard deviation for the comparative y-axis and x-axis peeled products as well as the z-axis peeled invention material are presented in Table 2 below.

Landscapes

• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Cell Electrode Carriers And Collectors (AREA)
• Battery Electrode And Active Subsutance (AREA)
• Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)

Priority Applications (4)

Applications Claiming Priority (4)

Publications (1)

Family

ID=26783609

Family Applications (1)

Country Status (7)

Cited By (1)

Families Citing this family (37)

Citations (13)

Family Cites Families (1)

• 1999
  • 1999-06-23 US US09/338,427 patent/US6383687B1/en not_active Expired - Lifetime
  • 1999-06-23 JP JP2000556921A patent/JP2002519214A/ja active Pending
  • 1999-06-23 ES ES99930608T patent/ES2237924T3/es not_active Expired - Lifetime
  • 1999-06-23 WO PCT/US1999/014226 patent/WO2000000345A1/en not_active Ceased
  • 1999-06-23 EP EP99930608A patent/EP1091841B1/en not_active Expired - Lifetime
  • 1999-06-23 DE DE69923682T patent/DE69923682T2/de not_active Expired - Fee Related
  • 1999-06-23 AT AT99930608T patent/ATE288819T1/de not_active IP Right Cessation

Patent Citations (13)

Non-Patent Citations (4)

Also Published As

Similar Documents

Legal Events