WO2011149241A2 - Polyimide porous web, method for manufacturing the same, and electrolyte membrane comprising the same - Google Patents

Polyimide porous web, method for manufacturing the same, and electrolyte membrane comprising the same Download PDF

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Publication number
WO2011149241A2
WO2011149241A2 PCT/KR2011/003787 KR2011003787W WO2011149241A2 WO 2011149241 A2 WO2011149241 A2 WO 2011149241A2 KR 2011003787 W KR2011003787 W KR 2011003787W WO 2011149241 A2 WO2011149241 A2 WO 2011149241A2
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WO
WIPO (PCT)
Prior art keywords
porous web
polyimide
electrolyte membrane
pore diameter
change rate
Prior art date
Application number
PCT/KR2011/003787
Other languages
French (fr)
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WO2011149241A3 (en
Inventor
Yun Kyung Kang
Heung Ryul Oh
Original Assignee
Kolon Fashion Material.Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from KR20100048546A external-priority patent/KR101488546B1/en
Priority claimed from KR1020100048544A external-priority patent/KR101440659B1/en
Application filed by Kolon Fashion Material.Inc. filed Critical Kolon Fashion Material.Inc.
Priority to EP11786873.7A priority Critical patent/EP2576880B1/en
Priority to US13/698,198 priority patent/US20130084515A1/en
Priority to CN2011800234371A priority patent/CN102892938A/en
Priority to JP2013512533A priority patent/JP5855093B2/en
Publication of WO2011149241A2 publication Critical patent/WO2011149241A2/en
Publication of WO2011149241A3 publication Critical patent/WO2011149241A3/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/1069—Polymeric electrolyte materials characterised by the manufacturing processes
    • H01M8/1081—Polymeric electrolyte materials characterised by the manufacturing processes starting from solutions, dispersions or slurries exclusively of polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/38—Liquid-membrane separation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/58—Other polymers having nitrogen in the main chain, with or without oxygen or carbon only
    • B01D71/62—Polycondensates having nitrogen-containing heterocyclic rings in the main chain
    • B01D71/64—Polyimides; Polyamide-imides; Polyester-imides; Polyamide acids or similar polyimide precursors
    • 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
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
    • B29C48/07—Flat, e.g. panels
    • B29C48/08—Flat, e.g. panels flexible, e.g. films
    • 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
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/14—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the particular extruding conditions, e.g. in a modified atmosphere or by using vibration
    • B29C48/142—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the particular extruding conditions, e.g. in a modified atmosphere or by using vibration using force fields, e.g. gravity or electrical fields
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
    • C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
    • C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
    • D01D5/00—Formation of filaments, threads, or the like
    • D01D5/0007—Electro-spinning
    • D01D5/0061—Electro-spinning characterised by the electro-spinning apparatus
    • D01D5/0092—Electro-spinning characterised by the electro-spinning apparatus characterised by the electrical field, e.g. combined with a magnetic fields, using biased or alternating fields
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
    • D01F6/58—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products
    • D01F6/76—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products from other polycondensation products
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
    • D04H1/42—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
    • D04H1/4326—Condensation or reaction polymers
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/70—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres
    • D04H1/72—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres the fibres being randomly arranged
    • D04H1/728—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres the fibres being randomly arranged by electro-spinning
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H3/00—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length
    • D04H3/005—Synthetic yarns or filaments
    • D04H3/009—Condensation or reaction polymers
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H3/00—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length
    • D04H3/08—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length characterised by the method of strengthening or consolidating
    • D04H3/16—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length characterised by the method of strengthening or consolidating with bonds between thermoplastic filaments produced in association with filament formation, e.g. immediately following extrusion
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/1067—Polymeric electrolyte materials characterised by their physical properties, e.g. porosity, ionic conductivity or thickness
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/39—Electrospinning
    • 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
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • the present invention relates to a polyimide porous web, a method for manufacturing the same, and an electrolyte membrane comprising the same.
  • a porous web may be used in various fields owing to advantages such as large surface area and good porosity, for example, the porous web may be used for a water-cleaning filter, an air-cleaning filter, a complex material, and a separation membrane in a cell. Especially, the porous web may be applied to an electrolyte membrane for a fuel cell of an automobile.
  • the fuel cell directly converts a chemical energy generated from an oxidation of fuel into an electric energy.
  • the fuel cell has been spotlighted as a next-generation energy source since the fuel cell has advantages of high energy efficiency and eco-friendly properties of low environmental pollution.
  • the fuel cell is structured in such a manner that anode and cathode are respectively positioned at both ends of the fuel cell with an electrolyte membrane interposed therebetween.
  • a typical example of the fuel cell for the automobile may be a proton exchange membrane fuel cell using hydrogen gas as a fuel.
  • the electrolyte membrane used for the proton exchange membrane fuel cell serves as a path for transporting hydrogen ions generated in the anode to the cathode, whereby the electrolyte membrane should have basically good conductivity of the hydrogen ions.
  • the electrolyte membrane should be capable of facilitating to separate the hydrogen gas supplied to the anode and oxygen supplied to the cathode from each other.
  • the electrolyte membrane should have good mechanical strength, good dimensional stability, good chemical resistance, and low resistance loss at a high current density.
  • the electrolyte membrane should have good heat resistance, whereby the electrolyte membrane is not broken or damaged even when the fuel cell for the automobile is used at a high temperature for a long time.
  • an electrolyte membrane with improved mechanical strength which uses a porous polytetrafluoroethylene (Teflon: brand name, hereinafter, referred to as 'Teflon') membrane as a reinforcing agent, and uses the impregnated Nafion resin as an ion conductor.
  • Teflon brand name, hereinafter, referred to as 'Teflon'
  • the electrolyte membrane using both the porous Teflon membrane and the Nafion resin has the relatively-high mechanical strength, however, the relatively-low ion conductivity.
  • an adhesive strength of the Teflon is very low, an adhesive strength between the Teflon reinforcing agent and the Nafion resin may be lowered in accordance with the change of operating conditions such as temperature or humidity for an operation of the fuel cell, thereby deteriorating separability between hydrogen and oxygen.
  • the Teflon corresponding to fluorine-based polymer is apt to be impregnated only in the fluorine-based ion conductor resin such as the Nafion, it is difficult to apply the ion conductor of other materials except the fluorine-based ion conductor resin.
  • the porous Teflon as well as the Nafion resin is high-priced so that the economical efficiency is deteriorated for mass production.
  • an ordinary hydrocarbon-based resin may be used as the reinforcing agent, for example, polyethylene, polypropylene, polysulfone, polyethersulfone, and polyvinylidene fluoride; and a hydrocarbon-based resin including sulfonic acid group may be used as the ion conductor instead of the Nafion resin, which enables to improve efficiency and reduce manufacturing cost.
  • the hydrocarbon-based reinforcing agent for the membrane may be dissolved in an organic solvent, and may cause the deteriorated physical properties and heat resistance, whereby it cannot ensure durability.
  • nonwoven fabric prepared by the general method or hydrocarbon-based membrane in a film type manufactured by the general method for preparing the separation membrane it is difficult to make a thin film, and it has the low porosity, whereby may cause difficulties in adjusting pores.
  • the hydrocarbon-based membrane has the relatively-low ion conductivity; and easily deforms under the environments of high temperature and humidity so that the efficiency of the hydrocarbon-based membrane may be deteriorated, and more seriously, the hydrocarbon-based membrane may be broken or damaged.
  • the present invention is directed to a polyimide porous web, a method for manufacturing the same, and an electrolyte membrane comprising the same that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
  • An aspect of the present invention is to provide a polyimide porous web with good porosity, good dimensional stability, and uniform pore size.
  • Another aspect of the present invention is to provide a method for manufacturing a polyimide porous web with good porosity, good dimensional stability, and uniform pore size.
  • Another aspect of the present invention is to provide an electrolyte membrane with improved ion conductivity and good dimensional stability owing to ion conductors uniformly impregnated in a porous web.
  • a polyimide porous web having a porosity of 60% to 90%, wherein not less than 80% of entire pores of the porous web have a pore diameter which differs from an average pore diameter of the porous web by not more than 1.5 ⁇ m.
  • a method for manufacturing a polyimide porous web comprising: dissolving a polyimide precusor in an organic solvent to obtain a spinning solution; electrospinning the spinning solution at an electric field of 750 to 3,500 V/cm to obtain a polyimide precusor porous web comprising fibers having an average diameter of 40 to 5,000nm; and imidizing the polyimide precusor porous web to obtain a polyimide porous web.
  • an electrolyte membrane comprising: a polyimide porous web having a porosity of 60% to 90%, not less than 80% of entire pores of the porous web having a pore diameter which differs from an average pore diameter of the porous web by not more than 1.5 ⁇ m; and an ion conductor impregnated in the polyimide porous web, wherein the electrolyte membrane has a volume change rate less than 15%, the volume change rate defined by formula 1 below:
  • volume change rate(%) [(Va - Vb)/Vb] ⁇ 100,
  • Va is a volume of the electrolyte member after high-humidity treatment under a temperature of 80°C and a relative humidity of 90%
  • Vb is a volume of the electrolyte membrane before the high-humidity treatment.
  • an electrolyte membrane comprising: a polyimide porous web having a porosity of 60% to 90%, not less than 80% of entire pores of the porous web having a pore diameter which differs from an average pore diameter of the porous web by not more than 1.5 ⁇ m; and an ion conductor impregnated in the polyimide porous web, wherein the electrolyte membrane has a thickness change rate less than 8%, the thickness change rate defined by formula 2 below:
  • Ta is a thickness of the electrolyte member after high-humidity treatment for 4 hours under a temperature of 80°C and a relative humidity of 90%
  • Tb is a thickness of the electrolyte membrane before the high-humidity treatment.
  • a porous web is thinned with easiness, and a pore size can be adjusted easily.
  • a polyimide porous web according to the present invention is not dissolved in a typical organic solvent, and also has a high melting point, thereby obtaining good chemical resistance and heat resistance.
  • polyimide porous web according to the present invention has uniform pores, ion conductors are uniformly impregnated in the porous web.
  • an electrolyte membrane manufactured by the use of polyimide porous web according to the present invention may have improved ion conductivity and high dimensional stability.
  • the electrolyte membrane having the good properties according to the present invention may be used for a fuel cell or secondary cell which needs lightness in weight, high efficiency, and good stability.
  • FIG. 1 illustrates an SEM photograph showing a polyimide porous web according to one embodiment of the present invention.
  • FIG. 2 is a schematic view illustrating an electrospinning device according to one embodiment of the present invention.
  • FIG. 1 illustrates an SEM photograph showing a polyimide porous web according to one embodiment of the present invention.
  • the polyimide precusor is changed to polyimide by a chemical imidization or heat imidization.
  • an imidization rate is not less than 90%, thereby obtaining good heat resistance and chemical resistance. If the imidization rate is less than 90%, the porous web 10 might be dissolved in an organic solvent, whereby it might be difficult to maintain properties necessary for the porous web 10.
  • a melting point of the polyimide porous web 10 may be higher than 400°C. If the melting point of the porous web is lower than 400°C, the heat resistance is deteriorated so that the porous web 10 may deform easily. The deformation of the porous web 10 may cause deteriorated cell efficiency in a fuel cell or secondary cell manufactured by the use of porous web 10. Furthermore, manufactures with the porous web whose melting point is less than 400°C may have a serious problem such as explosion caused by abnormally-generated heat.
  • an electrospinning method enabling an easy control of a manufacturing process is applied, which facilitates to obtain a fiber 11 having a required diameter. Accordingly, it is possible to manufacture the porous web 10 whose porosity is not less than 60%.
  • 'porosity' means a fraction of the volume of pores 12 over the total volume of the web 10, which is calculated by the following formula.
  • the total volume is calculated by measuring width, length and thickness of a rectangle-shaped sample; and the air volume is obtained by subtracting a polymer volume from the total volume, wherein the polymer volume is calculated backward from a density after measuring a mass of the sample.
  • the porous web 10 has a large specific surface. Thus, an ion conductor is readily impregnated in the porous web 10, whereby a manufactured electrolyte membrane has good ion conductivity.
  • the porosity of the porous web 10 is more than 99%, it deteriorates dimensional stability so that the following processes may not be smoothly carried out. In this respect, it is preferable that the porosity of the porous web 10 be not more than 99%.
  • the polyimide porous web 10 according to the present invention may have an average thickness of 5 ⁇ 50 ⁇ m. If the thickness of the porous web 10 is less than 5 ⁇ m, the mechanical strength and dimensional stability of the porous web 10 may be considerably deteriorated. Meanwhile, if the thickness of the porous web 10 is more than 50 ⁇ m, it is disadvantageous to lightness and integration in the manufacture.
  • the fibers 11 constituting the porous web 10 have the average diameter of 40nm ⁇ 5,000 nm, preferably. If the average diameter is less than 40nm, the mechanical strength may be deteriorated. If the average diameter is more than 5,000nm, the porosity of the web 10 may be considerably deteriorated, and the thickness of the porous web 10 may be increased.
  • the polyimide porous web 10 according to the present invention may be used for manufacturing the electrolyte membrane for fuel cell.
  • the electrolyte membrane for fuel cell further includes the ion conductor as well as the porous web 10, to thereby smoothly transport ions.
  • the ion conductors should be uniformly impregnated in the entire porous web 10.
  • the average pore diameter of the porous web 10 is 0.05 ⁇ m ⁇ 3.0 ⁇ m, preferably.
  • the average pore diameter of the porous web 10 is less than 0.05 ⁇ m, the smooth impregnation of the ion conductors may be difficult.
  • the average pore diameter of the porous web 10 is more than 3.0 ⁇ m, the strength of the porous web 10 may be deteriorated, and the ion conductors are excessively impregnated in the porous web 10.
  • the ion conductors are concentrated only in the specific pores 12, thereby deteriorating the ion conductivity of the electrolyte membrane. That is, as the size of the pores 12 in the porous web 10 becomes more uniform, the ion conductors may be uniformly impregnated in the entire porous web 10, whereby the electrolyte membrane may have the good ion conductivity.
  • not less than 80% of entire pores of the porous web 10 have the pore diameter which differs from the average pore diameter of the porous web 10 by not more than 1.5 ⁇ m. The uniformity of the pore size may be achieved by a precise control of the electrospinning process.
  • the electrolyte membrane for fuel cell that is, one of application fields of the polyimide porous web 10 may be easily exposed to the environments of high temperature and humidity. In this respect, good dimensional stability is necessary for the electrolyte membrane for fuel cell. If not, the electrolyte membrane and electrode may be separated at their interface, thereby deteriorating the cell efficiency of the fuel cell.
  • volume change rate and thickness change rate under the environmental conditions similar to those of the environment when the fuel cell is operated are calculated by the following formulas 1 and 2, to thereby evaluate the dimensional stability.
  • Volume change rate(%) [(Va - Vb) / Vb] ⁇ 100,
  • 'Va' is the volume of the electrolyte membrane after a high humidity treatment under the conditions of 80°C temperature and 90% relative humidity for 4 hours; and 'Vb' is the volume of the electrolyte membrane before the high humidity treatment.
  • Thickness change rate(%) [(Ta - Tb) / Tb] ⁇ 100,
  • 'Ta' is the thickness of the electrolyte membrane after a high humidity treatment maintained under the conditions of 80°C temperature and 90% relative humidity for 4 hours; and 'Tb' is the thickness of the electrolyte membrane before the high humidity treatment.
  • the electrolyte membrane cut in a size of 10cm ⁇ 10cm is left in a thermo-hygrostat maintained under the operation environments for the fuel cell, that is, 80°C temperature and 90% relative humidity for 4 hours, the changed volume and thickness of the electrolyte membrane are measured, and are then applied to the above formulas, to thereby obtain the volume change rate and thickness change rate of the electrolyte membrane.
  • the volume change rate of the electrolyte membrane may be a reference to check efficiency deterioration and stability by the damage of the electrolyte membrane and the interfacial separation under the high temperature and humidity.
  • the thickness change rate of the electrolyte membrane may be a reference to check durability and stability of fuel cell stack including several tens to several hundreds of electrolyte membranes.
  • the ion conductors are uniformly impregnated in the porous web 10 with the uniform pores, thereby resulting in the good dimensional stability of the electrolyte membrane.
  • the electrolyte membrane of the present invention may have the volume change rate not more than 15% and the thickness change rate not more than 8%.
  • the electrolyte membrane with the good dimensional stability according to the present invention allows high reliability in the fuel cell requiring high stability.
  • FIG. 2 is a schematic view illustrating an electrospinning device according to one embodiment of the present invention.
  • the porous web 10 of the present invention is manufactured by the electrospinning process, it is possible to precisely control the average diameter of the fibers constituting the web 10, to thereby manufacture the porous web having the uniform pore size and the high porosity.
  • the polyimide for the porous web 10 according to the present invention is not dissolved in the organic solvent, it cannot be directly applied to the electrospining process. That is, a spinning solution for electrospining cannot be made by the use of polyimide.
  • the spinning solution for electrospinning is prepared by dissolving the polyimide precusor in the organic solvent; and a bundle of fibers is manufactured by electrospinning the prepared spinning solution. Then, the manufactured polyimide precursor porous web is imidized so that the polyimide porous web 10 is finally manufactured.
  • the polyimide precursor may use polyamic acid.
  • the polyamic acid may be prepared by polymerizing diamine and dianhydride.
  • the dianhydride may be prepared by at least one among PMDA (pyromellyrtic dianhydride), BTDA (Benzophenonetetracarboxylic dianhydride), ODPA(4,4'-oxydiphthalic anhydride), BPDA (biphenyltetracarboxylic dianhydride), and SIDA(bis(3,4-dicarboxyphenyl) dimethylsilane dianhydride).
  • the diamine may be prepared by at least one among ODA(4,4'-oxydianiline), p-PDA(p-penylene diamine), and o-PDA(openylene diamine).
  • a solvent used for dissolving the polyamic acid may be at least one among m-cresol, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAc), dimethylsulfoxide (DMSO), acetone, diethylacetate, tetrahydrofuran (THF), chloroform, and ⁇ -butyrolactone.
  • a concentration of the polyamic acid may be 5 ⁇ 20 weight%. If the concentration of the polyamic acid is less than 5 weight%, the unsmooth spinning makes it difficult to manufacture the fiber 11 normally or to manufacture the fiber 11 with the uniform diameter. Meanwhile, if the concentration of the polyamic acid is more than 20 weight%, a discharge pressure is rapidly increased so that the spinning is not performed or the process efficiency is deteriorated.
  • the polyimide precursor porous web including the fibers 11 with the average diameter of 40nm ⁇ 5,000nm is manufactured by the use of electrospinning device with the manufactured spinning solution, as shown in FIG. 2. That is, the spinning solution stored in a solution tank is constantly supplied to a spinning unit by the use of controlled-volume pump; and then the spinning solution is discharged via a nozzle 2 of the spinning unit, and is coagulated almost simultaneously with the discharging, to thereby prepare the fibers 4. The prepared fibers 4 are collected in a collector 5, thereby manufacturing the polyimide precursor porous web.
  • an electric field applied by a high-voltage generator 3 occurs between the collector 5 and the spinning unit, wherein an intensity of the electric field may be 750 ⁇ 3,500V/cm. If the intensity of electric field is less than 750V/cm, the spinning solution is not continually discharged so that the porous web with the uniform thickness is not manufactured. Also, since the fiber 4 coagulated after being spun and scattered is not smoothly collected in the collector 5, it is difficult to manufacture the porous web. Meanwhile, if the intensity of electric field is more than 3,500V/cm, the coagulated fiber 4 is not precisely collected in the collector 5, whereby it is difficult to obtain the porous web 10 with the normal shape.
  • the polyimide porous web 10 is manufactured by imidizing the polyimide precursor porous web.
  • This imidization may be performed by selectively using a heat imidization process or a chemical imidization process, or by jointly using the heat imidization process and chemical imidization process.
  • the chemical imidization process may be carried out by adding a dehydration agent such acetic anhydride and/or imidization catalyst such as pyridine to the spinning solution before the electrospinning process, or by treating the polyimide precursor porous web with the dehydration agent and/or imidization catalyst after the electrospinning process.
  • a dehydration agent such as acetic anhydride and/or imidization catalyst such as pyridine
  • the heat imidization process may be carried out by heating the polyimide precursor porous web at a temperature of 80 ⁇ 400°C.
  • the imidization process is carried out at a draw rate not more than 0.2.
  • the draw rate is not more than 0.2, preferably. If the draw rate is more than 0.2, the uniform thickness is not obtained due to the deformation of the porous web 10, and the tensile strength is deteriorated due to the low cohesive force. Meanwhile, the lower limit of the draw rate may be 0.0 corresponding to the non-drawn state, or may be not more than 0.1 corresponding to the excessively-drawn state, thereby realizing the smooth process, preventing deterioration of the porosity, and obtaining the appropriate thickness.
  • the polyimide porous web 10 has the imidization rate not less than 90% by the above imidization process. If the imidization rate is less than 90%, the heat resistance and chemical resistance of the porous web 10 may be deteriorated.
  • the embodiments 1 to 5 and comparative examples 1 to 4 exemplarily describe the manufacturing method of the porous web using the polyimide precursor, which are provided to help a clear understanding of the present invention, and are not intended to limit the scope of the present invention.
  • the manufactured spinning solution is spun via the nozzle 2 provided in the electrospinning device by the use of controlled-volume pump 1. Under the condition that an electric field is applied by the high-voltage generator 3, the spun spinning solution is scattered and coagulated fibers 4, to thereby prepare fibers 4. The coagulated fibers 4 are collected in the collector 5, thereby manufacturing a polyimide precursor porous web. At this time, a viscosity of the spinning solution is 40,000cPs, and the applied electric field is 2,500 V/cm.
  • the polyimide precursor porous web is heated for 30 minutes by the use of hot press maintained at 200°C temperature, thereby manufacturing a polyimide porous web whose imidization rate is 99% and thickness is 30 ⁇ m.
  • a polyimide porous web having 30 ⁇ m thickness is manufactured in the same method as described in the above embodiment 1 except that the electric field of 3,500 V/cm or 750 V/cm is applied.
  • a polyimide porous web having 30 ⁇ m thickness is manufactured in the same method as described in the above embodiment 1 except that the spinning solution having the concentration of 8 weight% and the viscosity of 20,000cPs, or having the concentration of 18 weight% and the viscosity of 70,000cPs is used selectively.
  • An electrospinning process is performed in the same method as described in the above embodiment 1 except that the electric field of 3,600 V/cm or 650 V/cm is applied.
  • An electrospinning process is performed in the same method as described in the above embodiment 1 except that the spinning solution having the concentration of 4 weight% and the viscosity of 16,000cPs, or having the concentration of 25 weight% and the viscosity of 120,000cPs is used selectively.
  • the porous webs provided by the above embodiments 1 to 5 and comparative examples 1 to 4 have the average pore diameter; the rate of pores having the pore diameter which differs from the average pore diameter of the porous web by not more than 1.5 ⁇ m with respect to the entire pores; the porosity; the average diameter of fiber; the thermal stability; and the tensile strength, which are measured by the following methods, and are shown in the following Table 1.
  • the average pore diameter is indirectly measured by the use of image analyzer of electron microscope (Model No.: JSM6700F with magnification of 1.0K, manufactured by JEOL).
  • image analyzer of electron microscope Model No.: JSM6700F with magnification of 1.0K, manufactured by JEOL.
  • an image is firstly obtained through an image-analyzing process using the electron microscope.
  • a pore portion that is, 'A' area is measured from the image, wherein 'A' area corresponding to the pore portion is shown as a black-colored portion in the image.
  • 'B' corresponds to the number of effective pores, that is, the number of black image pieces in the 'A' and the black-colored portion of the image obtained by the electron microscope except defect and shadow of the image.
  • a cell density may be calculated by applying the measured 'A' and 'B' to the following formula; and the average pore diameter may be calculated by the following formula using the cell density.
  • Constant value density of fiber base material polymer / density of porous web
  • Average pore diameter [(constant value - 1) ⁇ 6 / ( ⁇ ⁇ cell density)] ⁇ 1/3 ⁇ 104
  • the rate of pores having the pore diameter which differs from the average pore diameter of the porous web by not more than 1.5 ⁇ m with respect to the entire pores is measured based on the contents stated in 'Mercury porosimeter win9400 series v. 1.02'.
  • a pressure of 200 mmHg is applied for 10 minutes; a pressure of mercury is 0.49psi; equilibrium time is set to be equal to 10 seconds; and a maximum permeation volume is set to 100,00 ml/g.
  • equilibrium time is set to be equal to 10 seconds; and a maximum permeation volume is set to 100,00 ml/g.
  • the porosity in each porous web may be obtained by calculating the rate of air volume with respect to the total volume by the following formula. At this time, the total volume is calculated by measuring the width, length and thickness of the prepared sample; and the air volume is obtained by subtracting the polymer volume from the total volume, wherein the polymer volume is calculated backward from the density after measuring the mass of the sample.
  • a length of the thickest portion in 40 fiber strands non-overlapped is measured from a digital photograph taken by the use of scanning electron microscope (SEM) with magnification of 500 or more; the measured length is calculated in terms of pixel number; and then the mean of the measured values is calculated.
  • SEM scanning electron microscope
  • the porous web is regarded as having thermal stability when a specific peak is not shown for the 2nd run measurement with differential scanning calorimetry (DSC) under the conditions of 20 ⁇ 200°C temperature and 20°C/minute heating rate.
  • DSC differential scanning calorimetry
  • the tensile strength of reinforcing agent and reinforced composite membrane may be measured based on a test method of ISO 527-5:2009(Plastics-Determination of tensile properties).
  • the polyimide porous web prepared by the above embodiment 1 is used as the reinforcing agent. Then, the polyimide porous web is twice impregnated in the prepared ion conductor solution for 20 minutes, and is left for 1 hour while under the reduced pressure; and then is dried for 3 hours by a hot air at 80°C, thereby manufacturing an electrolyte membrane having 50 ⁇ m thickness.
  • An electrolyte membrane having 50 ⁇ m thickness is manufactured in the same method as described in the above embodiment 6 except that the polyimide porous web prepared by the above embodiment 2 or 3 is used as the reinforcing agent.
  • An electrolyte membrane having 50 ⁇ m thickness is manufactured in the same method as described in the above embodiment 6 except that the polyimide porous web prepared by the above embodiment 4 or 5 is used as the reinforcing agent.
  • An electrolyte membrane having 50 ⁇ m thickness is manufactured in the same method as described in the above embodiment 6 except that a PI porous film having 30 ⁇ m thickness is used as the reinforcing agent, wherein the PI porous film is manufactured by a porous film manufacturing method which forms pores in a film by mixing, discharging and solidifying solvent-soluble particles for a film-making process; and dissolving the mixed particles.
  • An electrolyte membrane having 50 ⁇ m thickness is manufactured in the same method as described in the above embodiment 6 except that ePTFE porous film (W.L.Gore, Teflon) having 30 ⁇ m thickness, which is already on the market, is used as the reinforcing agent.
  • ePTFE porous film W.L.Gore, Teflon
  • An electrolyte membrane having 50 ⁇ m thickness is manufactured by preparing 12 weight% of ion conductor solution by dissolving sulfonated polyimide in a solution of N-methyl-2-pyrrolidone; making a film from the prepared ion conductor solution; and drying the made film.
  • volume change rate and thickness change rate of the electrolyte membranes prepared by the above embodiments 6 to 8 and comparative examples 5 to 7 are measured by the following methods, which will be shown in the following Table 2.
  • the volume(Va) is obtained by measuring the respective lengths in the x-axis, y-axis, and z-axis of the changed electrolyte membrane; and the volume(Vb) is obtained before the above humidity treatment.
  • the volume change rate of the electrolyte membrane is obtained by applying the obtained (Va) and (Vb) to the following formula.
  • Volume change rate(%) [(Va - Vb) / Vb] ⁇ 100
  • the thickness change rate is obtained by applying the thickness(Ta) of the electrolyte member after the high temperature and humidity treatment whose conditions are the same as those described in the above volume change rate, and the thickness(Tb) of the electrolyte member before the high temperature and humidity treatment into the following formula.
  • Thickness change rate(%) [(Ta - Tb) / Tb] ⁇ 100

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Abstract

Disclosed is a polyimide porous web with good porosity, good dimensional stability, and uniform pore; a method for manufacturing the same; and an electrolyte membrane with improved ion conductivity and good dimensional stability owing to ion conductors uniformly impregnated in the porous web, the polyimide porous web having a porosity of 60% to 90%, wherein not less than 80% of entire pores of the porous web have a pore diameter which differs from an average pore diameter of the porous web by not more than 1.5㎛.

Description

POLYIMIDE POROUS WEB, METHOD FOR MANUFACTURING THE SAME, AND ELECTROLYTE MEMBRANE COMPRISING THE SAME
The present invention relates to a polyimide porous web, a method for manufacturing the same, and an electrolyte membrane comprising the same.
A porous web may be used in various fields owing to advantages such as large surface area and good porosity, for example, the porous web may be used for a water-cleaning filter, an air-cleaning filter, a complex material, and a separation membrane in a cell. Especially, the porous web may be applied to an electrolyte membrane for a fuel cell of an automobile.
The fuel cell directly converts a chemical energy generated from an oxidation of fuel into an electric energy. The fuel cell has been spotlighted as a next-generation energy source since the fuel cell has advantages of high energy efficiency and eco-friendly properties of low environmental pollution. The fuel cell is structured in such a manner that anode and cathode are respectively positioned at both ends of the fuel cell with an electrolyte membrane interposed therebetween.
A typical example of the fuel cell for the automobile may be a proton exchange membrane fuel cell using hydrogen gas as a fuel. The electrolyte membrane used for the proton exchange membrane fuel cell serves as a path for transporting hydrogen ions generated in the anode to the cathode, whereby the electrolyte membrane should have basically good conductivity of the hydrogen ions. Also, the electrolyte membrane should be capable of facilitating to separate the hydrogen gas supplied to the anode and oxygen supplied to the cathode from each other. In addition, the electrolyte membrane should have good mechanical strength, good dimensional stability, good chemical resistance, and low resistance loss at a high current density. Especially, the electrolyte membrane should have good heat resistance, whereby the electrolyte membrane is not broken or damaged even when the fuel cell for the automobile is used at a high temperature for a long time.
Recently-used electrolyte membrane for the fuel cell is fluorine-based resin, that is, perfluoro-sulfone acid resin (Nafion: brand name, hereinafter, referred to as 'Nafion resin'). However, since the Nafion resin has low mechanical strength, the long-term use Nafion resin may have a pin-hole therein, thereby deteriorating energy conversion efficiency. There was an attempt to increase a thickness of the Nafion resin for intensification of the mechanical strength. In this case, resistance loss is increased and economical efficiency is deteriorated due to the increase of thickness.
In order to overcome these problems, there has been proposed an electrolyte membrane with improved mechanical strength, which uses a porous polytetrafluoroethylene (Teflon: brand name, hereinafter, referred to as 'Teflon') membrane as a reinforcing agent, and uses the impregnated Nafion resin as an ion conductor. In comparison to the electrolyte membrane formed only of the Nafion resin, the electrolyte membrane using both the porous Teflon membrane and the Nafion resin has the relatively-high mechanical strength, however, the relatively-low ion conductivity. Also, since an adhesive strength of the Teflon is very low, an adhesive strength between the Teflon reinforcing agent and the Nafion resin may be lowered in accordance with the change of operating conditions such as temperature or humidity for an operation of the fuel cell, thereby deteriorating separability between hydrogen and oxygen. Also, since the Teflon corresponding to fluorine-based polymer is apt to be impregnated only in the fluorine-based ion conductor resin such as the Nafion, it is difficult to apply the ion conductor of other materials except the fluorine-based ion conductor resin. Furthermore, the porous Teflon as well as the Nafion resin is high-priced so that the economical efficiency is deteriorated for mass production.
In order to overcome these problems, instead of the Teflon reinforcing agent, an ordinary hydrocarbon-based resin may be used as the reinforcing agent, for example, polyethylene, polypropylene, polysulfone, polyethersulfone, and polyvinylidene fluoride; and a hydrocarbon-based resin including sulfonic acid group may be used as the ion conductor instead of the Nafion resin, which enables to improve efficiency and reduce manufacturing cost.
In this case, the reduced manufacturing cost allows the improved economical efficiency. However, the hydrocarbon-based reinforcing agent for the membrane may be dissolved in an organic solvent, and may cause the deteriorated physical properties and heat resistance, whereby it cannot ensure durability.
Also, in case of nonwoven fabric prepared by the general method or hydrocarbon-based membrane in a film type manufactured by the general method for preparing the separation membrane, it is difficult to make a thin film, and it has the low porosity, whereby may cause difficulties in adjusting pores.
Especially, due to difficulties in adjustment of pore size, pore sizes of the hydrocarbon-based membrane are not uniform, and the ion conductors are impregnated without uniformity. As a result, the hydrocarbon-based membrane has the relatively-low ion conductivity; and easily deforms under the environments of high temperature and humidity so that the efficiency of the hydrocarbon-based membrane may be deteriorated, and more seriously, the hydrocarbon-based membrane may be broken or damaged.
Therefore, the present invention is directed to a polyimide porous web, a method for manufacturing the same, and an electrolyte membrane comprising the same that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An aspect of the present invention is to provide a polyimide porous web with good porosity, good dimensional stability, and uniform pore size.
Another aspect of the present invention is to provide a method for manufacturing a polyimide porous web with good porosity, good dimensional stability, and uniform pore size.
Another aspect of the present invention is to provide an electrolyte membrane with improved ion conductivity and good dimensional stability owing to ion conductors uniformly impregnated in a porous web.
To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, there is provided a polyimide porous web having a porosity of 60% to 90%, wherein not less than 80% of entire pores of the porous web have a pore diameter which differs from an average pore diameter of the porous web by not more than 1.5㎛.
In another aspect of the present invention, there is provided a method for manufacturing a polyimide porous web comprising: dissolving a polyimide precusor in an organic solvent to obtain a spinning solution; electrospinning the spinning solution at an electric field of 750 to 3,500 V/㎝ to obtain a polyimide precusor porous web comprising fibers having an average diameter of 40 to 5,000㎚; and imidizing the polyimide precusor porous web to obtain a polyimide porous web.
In another aspect of the present invention, there is provided an electrolyte membrane comprising: a polyimide porous web having a porosity of 60% to 90%, not less than 80% of entire pores of the porous web having a pore diameter which differs from an average pore diameter of the porous web by not more than 1.5㎛; and an ion conductor impregnated in the polyimide porous web, wherein the electrolyte membrane has a volume change rate less than 15%, the volume change rate defined by formula 1 below:
formula 1: volume change rate(%) = [(Va - Vb)/Vb]×100,
wherein Va is a volume of the electrolyte member after high-humidity treatment under a temperature of 80℃ and a relative humidity of 90%, and Vb is a volume of the electrolyte membrane before the high-humidity treatment.
In a further aspect of the present invention, there is provided an electrolyte membrane comprising: a polyimide porous web having a porosity of 60% to 90%, not less than 80% of entire pores of the porous web having a pore diameter which differs from an average pore diameter of the porous web by not more than 1.5㎛; and an ion conductor impregnated in the polyimide porous web, wherein the electrolyte membrane has a thickness change rate less than 8%, the thickness change rate defined by formula 2 below:
formula 2: thickness change rate(%) = [(Ta - Tb)/Tb]×100,
wherein Ta is a thickness of the electrolyte member after high-humidity treatment for 4 hours under a temperature of 80℃ and a relative humidity of 90%, and Tb is a thickness of the electrolyte membrane before the high-humidity treatment.
According to a method for manufacturing a polyimide porous web of the present invention, a porous web is thinned with easiness, and a pore size can be adjusted easily.
Also, a polyimide porous web according to the present invention is not dissolved in a typical organic solvent, and also has a high melting point, thereby obtaining good chemical resistance and heat resistance.
Also, since the polyimide porous web according to the present invention has uniform pores, ion conductors are uniformly impregnated in the porous web. Thus, an electrolyte membrane manufactured by the use of polyimide porous web according to the present invention may have improved ion conductivity and high dimensional stability.
The electrolyte membrane having the good properties according to the present invention may be used for a fuel cell or secondary cell which needs lightness in weight, high efficiency, and good stability.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
FIG. 1 illustrates an SEM photograph showing a polyimide porous web according to one embodiment of the present invention.
FIG. 2 is a schematic view illustrating an electrospinning device according to one embodiment of the present invention.
Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.
Hereinafter, a polyimide porous web according to one embodiment of the present invention will be described with reference to the accompanying drawings.
FIG. 1 illustrates an SEM photograph showing a polyimide porous web according to one embodiment of the present invention.
According to the present invention, after a porous web is made by the use of polyimide precursor through an electrospinning process, the polyimide precusor is changed to polyimide by a chemical imidization or heat imidization.
In case of the polyimide porous web 10 according to one embodiment of the present invention, an imidization rate is not less than 90%, thereby obtaining good heat resistance and chemical resistance. If the imidization rate is less than 90%, the porous web 10 might be dissolved in an organic solvent, whereby it might be difficult to maintain properties necessary for the porous web 10.
As the imidization rate of the polyimide porous web 10 according to the present invention is not less than 90%, a melting point of the polyimide porous web 10 may be higher than 400℃. If the melting point of the porous web is lower than 400℃, the heat resistance is deteriorated so that the porous web 10 may deform easily. The deformation of the porous web 10 may cause deteriorated cell efficiency in a fuel cell or secondary cell manufactured by the use of porous web 10. Furthermore, manufactures with the porous web whose melting point is less than 400℃ may have a serious problem such as explosion caused by abnormally-generated heat.
For manufacturing the polyimide porous web 10 according to the present invention, an electrospinning method enabling an easy control of a manufacturing process is applied, which facilitates to obtain a fiber 11 having a required diameter. Accordingly, it is possible to manufacture the porous web 10 whose porosity is not less than 60%.
In this specification, 'porosity' means a fraction of the volume of pores 12 over the total volume of the web 10, which is calculated by the following formula.
Porosity(%) = (air volume / total volume) × 100
In this case, the total volume is calculated by measuring width, length and thickness of a rectangle-shaped sample; and the air volume is obtained by subtracting a polymer volume from the total volume, wherein the polymer volume is calculated backward from a density after measuring a mass of the sample.
If the porosity of the porous web 10 is not less than 60%, the porous web 10 has a large specific surface. Thus, an ion conductor is readily impregnated in the porous web 10, whereby a manufactured electrolyte membrane has good ion conductivity.
Meanwhile, if the porosity of the porous web 10 is more than 99%, it deteriorates dimensional stability so that the following processes may not be smoothly carried out. In this respect, it is preferable that the porosity of the porous web 10 be not more than 99%.
The polyimide porous web 10 according to the present invention may have an average thickness of 5 ~ 50㎛. If the thickness of the porous web 10 is less than 5㎛, the mechanical strength and dimensional stability of the porous web 10 may be considerably deteriorated. Meanwhile, if the thickness of the porous web 10 is more than 50㎛, it is disadvantageous to lightness and integration in the manufacture.
In order to manufacture the polyimide porous web 10 having the porosity of 60% ~ 99% and the thickness of 5㎛ ~ 50㎛ according to the present invention, the fibers 11 constituting the porous web 10 have the average diameter of 40㎚ ~ 5,000 ㎚, preferably. If the average diameter is less than 40㎚, the mechanical strength may be deteriorated. If the average diameter is more than 5,000㎚, the porosity of the web 10 may be considerably deteriorated, and the thickness of the porous web 10 may be increased.
The polyimide porous web 10 according to the present invention may be used for manufacturing the electrolyte membrane for fuel cell. The electrolyte membrane for fuel cell further includes the ion conductor as well as the porous web 10, to thereby smoothly transport ions.
For the smooth transport of the ions in the electrolyte membrane, the ion conductors should be uniformly impregnated in the entire porous web 10. For the smooth impregnation of the ion conductors, the average pore diameter of the porous web 10 is 0.05㎛ ~ 3.0㎛, preferably. When the average pore diameter of the porous web 10 is less than 0.05㎛, the smooth impregnation of the ion conductors may be difficult. Meanwhile, when the average pore diameter of the porous web 10 is more than 3.0㎛, the strength of the porous web 10 may be deteriorated, and the ion conductors are excessively impregnated in the porous web 10.
If the size of the pores 12 in the porous web 10 is not uniform, the ion conductors are concentrated only in the specific pores 12, thereby deteriorating the ion conductivity of the electrolyte membrane. That is, as the size of the pores 12 in the porous web 10 becomes more uniform, the ion conductors may be uniformly impregnated in the entire porous web 10, whereby the electrolyte membrane may have the good ion conductivity. According to the present invention, not less than 80% of entire pores of the porous web 10 have the pore diameter which differs from the average pore diameter of the porous web 10 by not more than 1.5㎛. The uniformity of the pore size may be achieved by a precise control of the electrospinning process.
The electrolyte membrane for fuel cell, that is, one of application fields of the polyimide porous web 10 may be easily exposed to the environments of high temperature and humidity. In this respect, good dimensional stability is necessary for the electrolyte membrane for fuel cell. If not, the electrolyte membrane and electrode may be separated at their interface, thereby deteriorating the cell efficiency of the fuel cell.
In order to check whether or not the electrolyte membrane for fuel cell has the dimensional stability under the environments of high temperature and humidity, volume change rate and thickness change rate under the environmental conditions similar to those of the environment when the fuel cell is operated are calculated by the following formulas 1 and 2, to thereby evaluate the dimensional stability.
[Formula 1]
Volume change rate(%) = [(Va - Vb) / Vb] × 100,
wherein 'Va' is the volume of the electrolyte membrane after a high humidity treatment under the conditions of 80℃ temperature and 90% relative humidity for 4 hours; and 'Vb' is the volume of the electrolyte membrane before the high humidity treatment.
[Formula 2]
Thickness change rate(%) = [(Ta - Tb) / Tb] × 100,
wherein 'Ta' is the thickness of the electrolyte membrane after a high humidity treatment maintained under the conditions of 80℃ temperature and 90% relative humidity for 4 hours; and 'Tb' is the thickness of the electrolyte membrane before the high humidity treatment.
After the electrolyte membrane cut in a size of 10㎝ × 10㎝ is left in a thermo-hygrostat maintained under the operation environments for the fuel cell, that is, 80℃ temperature and 90% relative humidity for 4 hours, the changed volume and thickness of the electrolyte membrane are measured, and are then applied to the above formulas, to thereby obtain the volume change rate and thickness change rate of the electrolyte membrane.
The volume change rate of the electrolyte membrane may be a reference to check efficiency deterioration and stability by the damage of the electrolyte membrane and the interfacial separation under the high temperature and humidity. Also, the thickness change rate of the electrolyte membrane may be a reference to check durability and stability of fuel cell stack including several tens to several hundreds of electrolyte membranes.
According to the present invention, the ion conductors are uniformly impregnated in the porous web 10 with the uniform pores, thereby resulting in the good dimensional stability of the electrolyte membrane. As a result, the electrolyte membrane of the present invention may have the volume change rate not more than 15% and the thickness change rate not more than 8%. The electrolyte membrane with the good dimensional stability according to the present invention allows high reliability in the fuel cell requiring high stability.
A method for manufacturing the polyimide porous web 10 according to one embodiment of the present invention will be described with reference to FIG. 2. FIG. 2 is a schematic view illustrating an electrospinning device according to one embodiment of the present invention.
As mentioned above, since the porous web 10 of the present invention is manufactured by the electrospinning process, it is possible to precisely control the average diameter of the fibers constituting the web 10, to thereby manufacture the porous web having the uniform pore size and the high porosity.
However, since the polyimide for the porous web 10 according to the present invention is not dissolved in the organic solvent, it cannot be directly applied to the electrospining process. That is, a spinning solution for electrospining cannot be made by the use of polyimide.
According to the present invention, the spinning solution for electrospinning is prepared by dissolving the polyimide precusor in the organic solvent; and a bundle of fibers is manufactured by electrospinning the prepared spinning solution. Then, the manufactured polyimide precursor porous web is imidized so that the polyimide porous web 10 is finally manufactured.
The polyimide precursor may use polyamic acid. The polyamic acid may be prepared by polymerizing diamine and dianhydride. The dianhydride may be prepared by at least one among PMDA (pyromellyrtic dianhydride), BTDA (Benzophenonetetracarboxylic dianhydride), ODPA(4,4'-oxydiphthalic anhydride), BPDA (biphenyltetracarboxylic dianhydride), and SIDA(bis(3,4-dicarboxyphenyl) dimethylsilane dianhydride). The diamine may be prepared by at least one among ODA(4,4'-oxydianiline), p-PDA(p-penylene diamine), and o-PDA(openylene diamine).
A solvent used for dissolving the polyamic acid may be at least one among m-cresol, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAc), dimethylsulfoxide (DMSO), acetone, diethylacetate, tetrahydrofuran (THF), chloroform, and γ-butyrolactone.
In the spinning solution, a concentration of the polyamic acid may be 5 ~ 20 weight%. If the concentration of the polyamic acid is less than 5 weight%, the unsmooth spinning makes it difficult to manufacture the fiber 11 normally or to manufacture the fiber 11 with the uniform diameter. Meanwhile, if the concentration of the polyamic acid is more than 20 weight%, a discharge pressure is rapidly increased so that the spinning is not performed or the process efficiency is deteriorated.
The polyimide precursor porous web including the fibers 11 with the average diameter of 40㎚ ~ 5,000㎚ is manufactured by the use of electrospinning device with the manufactured spinning solution, as shown in FIG. 2. That is, the spinning solution stored in a solution tank is constantly supplied to a spinning unit by the use of controlled-volume pump; and then the spinning solution is discharged via a nozzle 2 of the spinning unit, and is coagulated almost simultaneously with the discharging, to thereby prepare the fibers 4. The prepared fibers 4 are collected in a collector 5, thereby manufacturing the polyimide precursor porous web.
At this time, an electric field applied by a high-voltage generator 3 occurs between the collector 5 and the spinning unit, wherein an intensity of the electric field may be 750 ~ 3,500V/㎝. If the intensity of electric field is less than 750V/㎝, the spinning solution is not continually discharged so that the porous web with the uniform thickness is not manufactured. Also, since the fiber 4 coagulated after being spun and scattered is not smoothly collected in the collector 5, it is difficult to manufacture the porous web. Meanwhile, if the intensity of electric field is more than 3,500V/㎝, the coagulated fiber 4 is not precisely collected in the collector 5, whereby it is difficult to obtain the porous web 10 with the normal shape.
Then, the polyimide porous web 10 is manufactured by imidizing the polyimide precursor porous web. This imidization may be performed by selectively using a heat imidization process or a chemical imidization process, or by jointly using the heat imidization process and chemical imidization process.
The chemical imidization process may be carried out by adding a dehydration agent such acetic anhydride and/or imidization catalyst such as pyridine to the spinning solution before the electrospinning process, or by treating the polyimide precursor porous web with the dehydration agent and/or imidization catalyst after the electrospinning process.
The heat imidization process may be carried out by heating the polyimide precursor porous web at a temperature of 80 ~ 400℃.
The imidization process is carried out at a draw rate not more than 0.2. In order to obtain the porous web 10 with the uniform pore and good porosity, the draw rate is not more than 0.2, preferably. If the draw rate is more than 0.2, the uniform thickness is not obtained due to the deformation of the porous web 10, and the tensile strength is deteriorated due to the low cohesive force. Meanwhile, the lower limit of the draw rate may be 0.0 corresponding to the non-drawn state, or may be not more than 0.1 corresponding to the excessively-drawn state, thereby realizing the smooth process, preventing deterioration of the porosity, and obtaining the appropriate thickness.
According to the present invention, the polyimide porous web 10 has the imidization rate not less than 90% by the above imidization process. If the imidization rate is less than 90%, the heat resistance and chemical resistance of the porous web 10 may be deteriorated.
Hereinafter, the effect of the present invention will be fully understood through the following embodiments and comparative examples of the present invention.
The embodiments 1 to 5 and comparative examples 1 to 4 exemplarily describe the manufacturing method of the porous web using the polyimide precursor, which are provided to help a clear understanding of the present invention, and are not intended to limit the scope of the present invention.
Embodiment 1
After 12 weight% of spinning solution is manufactured by dissolving polyamic acid in a solvent of dimethylformamide, the manufactured spinning solution is spun via the nozzle 2 provided in the electrospinning device by the use of controlled-volume pump 1. Under the condition that an electric field is applied by the high-voltage generator 3, the spun spinning solution is scattered and coagulated fibers 4, to thereby prepare fibers 4. The coagulated fibers 4 are collected in the collector 5, thereby manufacturing a polyimide precursor porous web. At this time, a viscosity of the spinning solution is 40,000cPs, and the applied electric field is 2,500 V/㎝.
Then, the polyimide precursor porous web is heated for 30 minutes by the use of hot press maintained at 200℃ temperature, thereby manufacturing a polyimide porous web whose imidization rate is 99% and thickness is 30㎛.
Embodiments 2 and 3
A polyimide porous web having 30㎛ thickness is manufactured in the same method as described in the above embodiment 1 except that the electric field of 3,500 V/㎝ or 750 V/㎝ is applied.
Embodiments 4 and 5
A polyimide porous web having 30㎛ thickness is manufactured in the same method as described in the above embodiment 1 except that the spinning solution having the concentration of 8 weight% and the viscosity of 20,000cPs, or having the concentration of 18 weight% and the viscosity of 70,000cPs is used selectively.
Comparative examples 1 and 2
An electrospinning process is performed in the same method as described in the above embodiment 1 except that the electric field of 3,600 V/㎝ or 650 V/㎝ is applied.
Comparative examples 3 and 4
An electrospinning process is performed in the same method as described in the above embodiment 1 except that the spinning solution having the concentration of 4 weight% and the viscosity of 16,000cPs, or having the concentration of 25 weight% and the viscosity of 120,000cPs is used selectively.
The porous webs provided by the above embodiments 1 to 5 and comparative examples 1 to 4 have the average pore diameter; the rate of pores having the pore diameter which differs from the average pore diameter of the porous web by not more than 1.5㎛ with respect to the entire pores; the porosity; the average diameter of fiber; the thermal stability; and the tensile strength, which are measured by the following methods, and are shown in the following Table 1.
Average pore diameter(㎛)
The average pore diameter is indirectly measured by the use of image analyzer of electron microscope (Model No.: JSM6700F with magnification of 1.0K, manufactured by JEOL). In more detail, in order to measure the average pore diameter, an image is firstly obtained through an image-analyzing process using the electron microscope. Then, a pore portion, that is, 'A' area is measured from the image, wherein 'A' area corresponding to the pore portion is shown as a black-colored portion in the image. Also, 'B' corresponds to the number of effective pores, that is, the number of black image pieces in the 'A' and the black-colored portion of the image obtained by the electron microscope except defect and shadow of the image. Thereafter, a cell density may be calculated by applying the measured 'A' and 'B' to the following formula; and the average pore diameter may be calculated by the following formula using the cell density.
Constant value = density of fiber base material polymer / density of porous web
Cell density = (B/A × 100) × 3/2 × 109 × constant value
Average pore diameter = [(constant value - 1) × 6 / (π × cell density)] × 1/3 × 104
Rate of pores having the pore diameter which differs from the average pore diameter by not more than 1.5㎛ with respect to the entire pores
The rate of pores having the pore diameter which differs from the average pore diameter of the porous web by not more than 1.5㎛ with respect to the entire pores is measured based on the contents stated in 'Mercury porosimeter win9400 series v. 1.02'. In more detail, under the low-pressure condition, a pressure of 200 mmHg is applied for 10 minutes; a pressure of mercury is 0.49psi; equilibrium time is set to be equal to 10 seconds; and a maximum permeation volume is set to 100,00 ㎖/g. Meanwhile, under the high-pressure condition, equilibrium time is set to be equal to 10 seconds; and a maximum permeation volume is set to 100,00 ㎖/g.
Porosity(%)
The porosity in each porous web may be obtained by calculating the rate of air volume with respect to the total volume by the following formula. At this time, the total volume is calculated by measuring the width, length and thickness of the prepared sample; and the air volume is obtained by subtracting the polymer volume from the total volume, wherein the polymer volume is calculated backward from the density after measuring the mass of the sample.
Porosity(%) = (air volume / total volume) × 100
Average diameter of fiber
A length of the thickest portion in 40 fiber strands non-overlapped is measured from a digital photograph taken by the use of scanning electron microscope (SEM) with magnification of 500 or more; the measured length is calculated in terms of pixel number; and then the mean of the measured values is calculated.
Thermal stability
The porous web is regarded as having thermal stability when a specific peak is not shown for the 2nd run measurement with differential scanning calorimetry (DSC) under the conditions of 20 ~ 200℃ temperature and 20℃/minute heating rate.
Tensile strength
The tensile strength of reinforcing agent and reinforced composite membrane may be measured based on a test method of ISO 527-5:2009(Plastics-Determination of tensile properties).
[Table 1]
Figure PCTKR2011003787-appb-I000001
The effect obtained when the polyimide porous webs proposed in the above embodiments 1 to 5 are used as the reinforcing agent of the electrolyte membrane will be illustrated by the following embodiments and comparative examples. These following embodiments and comparative examples are provided to help a clear understanding of the present invention, and are not intended to limit the scope of the present invention.
Embodiment 6
After 12 weight% of ion conductor solution is prepared by dissolving sulfonated polyimide in N-methyl-2-pyrrolidone, the polyimide porous web prepared by the above embodiment 1 is used as the reinforcing agent. Then, the polyimide porous web is twice impregnated in the prepared ion conductor solution for 20 minutes, and is left for 1 hour while under the reduced pressure; and then is dried for 3 hours by a hot air at 80℃, thereby manufacturing an electrolyte membrane having 50㎛ thickness.
Embodiments 7 and 8
An electrolyte membrane having 50㎛ thickness is manufactured in the same method as described in the above embodiment 6 except that the polyimide porous web prepared by the above embodiment 2 or 3 is used as the reinforcing agent.
Embodiments 9 and 10
An electrolyte membrane having 50㎛ thickness is manufactured in the same method as described in the above embodiment 6 except that the polyimide porous web prepared by the above embodiment 4 or 5 is used as the reinforcing agent.
Comparative example 5
An electrolyte membrane having 50㎛ thickness is manufactured in the same method as described in the above embodiment 6 except that a PI porous film having 30㎛ thickness is used as the reinforcing agent, wherein the PI porous film is manufactured by a porous film manufacturing method which forms pores in a film by mixing, discharging and solidifying solvent-soluble particles for a film-making process; and dissolving the mixed particles.
Comparative example 6
An electrolyte membrane having 50㎛ thickness is manufactured in the same method as described in the above embodiment 6 except that ePTFE porous film (W.L.Gore, Teflon) having 30㎛ thickness, which is already on the market, is used as the reinforcing agent.
Comparative example 7
An electrolyte membrane having 50㎛ thickness is manufactured by preparing 12 weight% of ion conductor solution by dissolving sulfonated polyimide in a solution of N-methyl-2-pyrrolidone; making a film from the prepared ion conductor solution; and drying the made film.
The volume change rate and thickness change rate of the electrolyte membranes prepared by the above embodiments 6 to 8 and comparative examples 5 to 7 are measured by the following methods, which will be shown in the following Table 2.
Volume change rate of electrolyte membrane(%)
After the electrolyte membrane cut in a size of 10㎝ 10㎝ is left in a thermo-hygrostat maintained under the operation environments for the fuel cell, that is, 80℃ temperature and 90% relative humidity for 4 hours, the volume(Va) is obtained by measuring the respective lengths in the x-axis, y-axis, and z-axis of the changed electrolyte membrane; and the volume(Vb) is obtained before the above humidity treatment. The volume change rate of the electrolyte membrane is obtained by applying the obtained (Va) and (Vb) to the following formula.
Volume change rate(%) = [(Va - Vb) / Vb] × 100
Thickness change rate(%)
The thickness change rate is obtained by applying the thickness(Ta) of the electrolyte member after the high temperature and humidity treatment whose conditions are the same as those described in the above volume change rate, and the thickness(Tb) of the electrolyte member before the high temperature and humidity treatment into the following formula.
Thickness change rate(%) = [(Ta - Tb) / Tb] × 100
[Table 2]
Figure PCTKR2011003787-appb-I000002

Claims (11)

  1. A polyimide porous web having a porosity of 60% to 90%, wherein not less than 80% of entire pores of the porous web have a pore diameter which differs from an average pore diameter of the porous web by not more than 1.5㎛.
  2. The polyimide porous web according to claim 1, wherein the average pore diameter is 0.05㎛ to 3.0㎛.
  3. The polyimide porous web according to claim 1, wherein the porous web comprises fibers having an average diameter of 40 ~ 5,000㎚.
  4. The polyimide porous web according to claim 1, wherein the porous web has a thermal stability at 20 ~ 200℃ temperature, wherein the polyimide porous web is regarded as having the thermal stability when a specific peak is not shown for a 2nd run measurement with differential scanning calorimetry under the conditions of 20 ~ 200℃ temperature and 20℃/minute heating rate.
  5. The polyimide porous web according to claim 1, wherein the porous web has a tensile strength not less than 15MPa.
  6. A method for manufacturing a polyimide porous web comprising:
    dissolving a polyimide precusor in an organic solvent to obtain a spinning solution;
    electrospinning the spinning solution at an electric field of 750 to 3,500 V/㎝ to obtain a polyimide precusor porous web comprising fibers having an average diameter of 40 to 5,000㎚; and
    imidizing the polyimide precusor porous web to obtain a polyimide porous web.
  7. The method according to claim 6, wherein the polyimide porous web has an imidization ratio not less than 90%.
  8. The method according to claim 6, wherein the polyimide precusor has a concentration of 5 to 20 weight% in the spinning solution.
  9. The method according to claim 6, wherein the spinning solution has a viscosity of 20,000 ~ 100,000cPs (measured at 25℃ by Brookfield viscometer).
  10. An electrolyte membrane comprising:
    a polyimide porous web having a porosity of 60% to 90%, not less than 80% of entire pores of the porous web having a pore diameter which differs from an average pore diameter of the porous web by not more than 1.5㎛; and
    an ion conductor impregnated in the polyimide porous web,
    wherein the electrolyte membrane has a volume change rate less than 15%, the volume change rate defined by formula 1 below:
    formula 1: volume change rate(%) = [(Va-Vb)/Vb]×100
    wherein Va is a volume of the electrolyte member after high-humidity treatment under a temperature of 80℃ and a relative humidity of 90%, and Vb is a volume of the electrolyte membrane before the high-humidity treatment
  11. An electrolyte membrane comprising:
    a polyimide porous web having a porosity of 60% to 90%, not less than 80% of entire pores of the porous web having a pore diameter which differs from an average pore diameter of the porous web by not more than 1.5㎛; and
    an ion conductor impregnated in the polyimide porous web,
    wherein the electrolyte membrane has a thickness change rate less than 8%, the thickness change rate defined by formula 2 below:
    formula 2: thickness change rate(%) = [(Ta-Tb)/Tb]×100
    wherein Ta is a thickness of the electrolyte member after high-humidity treatment for 4 hours under a temperature of 80℃ and a relative humidity of 90%, and Tb is a thickness of the electrolyte membrane before the high-humidity treatment.
PCT/KR2011/003787 2010-05-25 2011-05-24 Polyimide porous web, method for manufacturing the same, and electrolyte membrane comprising the same WO2011149241A2 (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2433696A3 (en) * 2010-09-28 2012-04-04 Evonik Fibres GmbH Process for producing a filter component, electrospinning process for producing a nanofibrous nonwoven, and process for increasing the cohesion of a nanofibrous nonwoven
US20130270179A1 (en) * 2012-04-11 2013-10-17 Xerox Corporation Polyimide membranes
JP2013256732A (en) * 2012-06-12 2013-12-26 Ube Ind Ltd Method for producing polyimide fiber
WO2018162866A1 (en) * 2017-03-10 2018-09-13 Sorbonne Université Composite membrane and method for manufacturing such a membrane

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120318752A1 (en) * 2010-12-20 2012-12-20 E.I. Du Pont De Nemours And Company High porosity high basis weight filter media
JP6101200B2 (en) * 2011-11-16 2017-03-22 住友電気工業株式会社 Insulated varnish and insulated wire using the same
CN103147253B (en) * 2013-03-05 2015-03-04 中国科学院理化技术研究所 High-strength polyimide nanofiber porous membrane and preparation method and application thereof
JP6340156B2 (en) * 2013-10-08 2018-06-06 株式会社 フューエンス Nanofiber structure
KR20150101039A (en) * 2014-02-25 2015-09-03 코오롱패션머티리얼 (주) Porous support, method for manufacturing the same, and reinforced membrane comprising the same
KR101451566B1 (en) 2014-02-25 2014-10-22 코오롱패션머티리얼 (주) Porous support, method for manufacturing the same, and reinforced membrane comprising the same
JP6502500B2 (en) * 2014-12-24 2019-04-17 コーロン ファッション マテリアル インコーポレイテッド Porous support excellent in packing characteristics of ion conductor, method for producing the same, and reinforced membrane containing the same
CN107614771A (en) * 2015-04-03 2018-01-19 株式会社未来科学 Nanofibrous structures
CN104928937B (en) * 2015-06-18 2017-02-01 中国地质大学（武汉） Porous polyimide/electrospinning polyimide fibrous composite material and application thereof
CN113206291A (en) * 2021-04-16 2021-08-03 华南理工大学 Polyimide/polyethylene oxide solid electrolyte composite membrane, preparation method and application

Family Cites Families (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001222988A (en) * 2000-02-08 2001-08-17 Teijin Ltd Polymer membrane carrying electrolyte and secondary battery therewith
JP4221888B2 (en) * 2000-09-20 2009-02-12 宇部興産株式会社 Continuous production method and continuous production apparatus for porous membrane
JP4425576B2 (en) * 2003-06-23 2010-03-03 日本バイリーン株式会社 Lithium secondary battery separator and lithium secondary battery
US20070074628A1 (en) * 2005-09-30 2007-04-05 Jones David C Coalescing filtration medium and process
US8689985B2 (en) * 2005-09-30 2014-04-08 E I Du Pont De Nemours And Company Filtration media for liquid filtration
JP2008002011A (en) * 2006-06-22 2008-01-10 Toyobo Co Ltd Polyimide nonwoven fabric and method for producing the same
KR100845239B1 (en) * 2006-08-07 2008-07-10 한국과학기술연구원 Separator having ultrafine fibrous layer with heat resistance and secondary battery having the same
JP4827781B2 (en) * 2007-03-30 2011-11-30 Ｎｏｋ株式会社 Polymer electrolyte membrane
JP5027554B2 (en) * 2007-04-27 2012-09-19 公立大学法人首都大学東京 Method and apparatus for producing uniaxial or multiaxially oriented nanofiber assembly
JP5300061B2 (en) * 2008-03-11 2013-09-25 公立大学法人首都大学東京 Nanofiber, electrolyte membrane, membrane electrode assembly, and fuel cell
KR101000214B1 (en) * 2008-05-28 2010-12-10 주식회사 엘지화학 Ion conductive resin fiber, ion conductive hybrid membrane, membrane-electrode assembly and fuel cell
KR101030738B1 (en) * 2008-08-01 2011-04-26 주식회사 아모그린텍 Carbon molded body prepared with carbon nanofibers web channel and method of preparing the same
KR20100035208A (en) * 2008-09-26 2010-04-05 주식회사 코오롱 Filter media and method of manufacturing the same
WO2010056659A1 (en) * 2008-11-14 2010-05-20 E. I. Du Pont De Nemours And Company Processes for making sheet structures having improved compression performance
US20110143217A1 (en) * 2009-12-15 2011-06-16 E. I. Du Pont De Nemours And Company Electrochemical cell comprising a separator comprising a nanoweb consisting essentially of nanofibers of fully aromatic polyimide

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2433696A3 (en) * 2010-09-28 2012-04-04 Evonik Fibres GmbH Process for producing a filter component, electrospinning process for producing a nanofibrous nonwoven, and process for increasing the cohesion of a nanofibrous nonwoven
US20130270179A1 (en) * 2012-04-11 2013-10-17 Xerox Corporation Polyimide membranes
US9272247B2 (en) * 2012-04-11 2016-03-01 Xerox Corporation Polyimide membranes
JP2013256732A (en) * 2012-06-12 2013-12-26 Ube Ind Ltd Method for producing polyimide fiber
WO2018162866A1 (en) * 2017-03-10 2018-09-13 Sorbonne Université Composite membrane and method for manufacturing such a membrane
FR3063743A1 (en) * 2017-03-10 2018-09-14 Sorbonne Université COMPOSITE MEMBRANE AND PROCESS FOR PRODUCING SUCH A MEMBRANE

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