WO2004021474A1 - Procede de production d'un separateur, notamment pour batteries ions-lithium - Google Patents

Procede de production d'un separateur, notamment pour batteries ions-lithium Download PDF

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Publication number
WO2004021474A1
WO2004021474A1 PCT/EP2003/007155 EP0307155W WO2004021474A1 WO 2004021474 A1 WO2004021474 A1 WO 2004021474A1 EP 0307155 W EP0307155 W EP 0307155W WO 2004021474 A1 WO2004021474 A1 WO 2004021474A1
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Prior art keywords
separator
substrate
coating
separators
battery
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PCT/EP2003/007155
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German (de)
English (en)
Inventor
Volker Hennige
Christian Hying
Gerhard HÖRPEL
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Creavis Gesellschaft Für Technologie Und Innovation Mbh
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Priority to AU2003249954A priority Critical patent/AU2003249954A1/en
Publication of WO2004021474A1 publication Critical patent/WO2004021474A1/fr

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/44—Fibrous material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • H01M50/451—Separators, membranes or diaphragms characterised by the material having a layered structure comprising layers of only organic material and layers containing inorganic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • H01M50/454—Separators, membranes or diaphragms characterised by the material having a layered structure comprising a non-fibrous layer and a fibrous layer superimposed on one another
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H01M50/491—Porosity
    • 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 invention relates to a method for producing a separator, in particular for use in a lithium-ion battery, and to the separator thus produced itself and to batteries equipped therewith.
  • An electrical separator is a separator that is used in batteries and other arrangements in which electrodes, e.g. B. must be separated from one another while maintaining ion conductivity.
  • the separator is usually a thin, porous, insulating material with high ion permeability, good mechanical strength and long-term stability against those in the system, e.g. B. in the electrolyte of the battery, chemicals and solvents used. It is intended to completely electronically isolate the cathode from the anode in batteries, but to be permeable to the electrolyte. He must also be permanently elastic and the movements in the system, for. B. in the electrode package when loading and unloading, follow.
  • the separator largely determines the life of the arrangement in which it is used, e.g. B. that of battery cells.
  • the development of rechargeable batteries is therefore accompanied by the development of suitable separator materials.
  • the separators currently in use mainly consist of porous organic polymer films or inorganic nonwovens, such as nonwovens made of glass or ceramic materials or ceramic papers These are manufactured by various companies and important producers here are: Celgard, Tonen,vine, Asahi, Binzer, Mitsubishi, Daramic and others .
  • a typical organic separator consists, for example, of polypropylene or a polypropylene / polyethylene / polypropylene composite ,
  • inorganic composite materials there are first attempts to use inorganic composite materials as separators.
  • DE 198 38 800 describes an electrical separator which comprises a flat, flexible substrate with a plurality of openings and a coating thereon, which is characterized in that the material of the substrate is selected from metals, alloys, plastics, Glass and carbon fiber or a combination of such materials and the coating is a continuous, porous, electrically non-conductive ceramic coating.
  • the separators which have a support made of electrically conductive material (as stated in the example), have proven to be unsuitable for lithium-ion cells, since the coating of the thickness described cannot be produced without defects over a large area and is therefore very easy to close Short circuits is coming.
  • DE 199 18 856 describes a separating element for batteries with non-aqueous electrolytes, in which polymer fibers are used as the substrate, to which a mixture of polymers and ceramics are applied, the ceramic content being very low.
  • These separators can be used up to a maximum of 120 ° C, since if this temperature is exceeded the ionic conductivity is interrupted.
  • a material can be realized which comprises a flat, flexible substrate provided with a plurality of openings with a coating on and in this substrate, the The material of the substrate is selected from woven or non-woven, non-electrically conductive fibers of glass or ceramic or a combination of such materials and the coating is a porous, electrically insulating, ceramic coating, and the resulting separator has a thickness of less than 100 ⁇ m and is bendable has a sufficiently low resistance in connection with the electrolyte and nevertheless has a sufficiently large long-term resistance.
  • the resistance of these separators is still too high for a large number of applications, since a glass fabric is used as the carrier, which is firstly too thick and secondly has too little porosity.
  • separators with the properties mentioned can be realized if polymeric substrate materials are used.
  • electrical separators which comprise a flat, multi-aperture, flexible substrate with a coating located on and in this substrate, the material of the substrate being selected from non-woven, non-electrically conductive fibers of polymers, and the coating is a porous, electrically insulating, ceramic coating.
  • the separator has a thickness of less than 35 ⁇ m, is bendable and shows a sufficiently low resistance in connection with an electrolyte and also has a sufficiently long-term resistance.
  • the temperature resistance of these separators is the same as that of the porous inorganic coating.
  • the present invention therefore relates to a process for the continuous production of a separator, comprising a flat, flexible substrate provided with a plurality of openings and having a porous, inorganic, electrically insulating coating on and in this substrate, the material of the substrate being selected made of non-woven, non-electrically conductive polymer fibers and the substrate has a porosity of greater than 50%, in which the substrate is unwound from a roll, undergoes a coating process in which the substrate is provided with the coating, and the finished separator on a second roll is wound, which is characterized in that the substrate has a maximum tension in the longitudinal direction of 10 N / cm during the coating process and undergoes a temperature treatment.
  • the present invention also relates to a separator produced by the method according to the invention.
  • the present invention also relates to a battery having a separator according to the invention.
  • the method according to the invention is suitable for producing separators, separators being understood to mean electrical separators which, for. B. electrically separate two differently charged electrodes.
  • separators being understood to mean electrical separators which, for. B. electrically separate two differently charged electrodes.
  • an electrolyte is required in addition to the separator, which enables ions to flow from one electrode through the separator to the other electrode.
  • the electrolyte is selected depending on the chemical system used in the battery.
  • the larger the pores in a separator the lower the resistance that arises when the pores are filled with a suitable electrolyte.
  • the selection of suitable particles can influence the porosity of the separator, which in the same way leads to changed properties.
  • a frequently used parameter of a separator in this context is the Gurley number. It is a measure of the gas permeability of the dry porous separator. As described by O. Besenhard in the "Handbook of Battery Materials", one can deduce the conductivity of a known system directly from the Gurley number.
  • Gurley number 10 when the pore diameter is around 100 nm and 30 when the pore diameter is around 50 nm.
  • Polymer separators for example, provide the safety currently required for lithium batteries by starting at a certain temperature (the shutdown temperature, which is approx. 120 ° C) prevent any current transport through the electrolyte. This happens because the pore structure of the separator collapses at this temperature and all pores are closed. Because no more ions can be transported, the dangerous reaction that can lead to the explosion comes to a standstill. If the cell is heated further due to external circumstances, the breakdown temperature is exceeded at approx. 165 ° C. From this temperature, the separator melts and contracts. At many points in the battery cell there is now a direct contact between the two electrodes and thus a large internal short circuit. This leads to an uncontrolled reaction, which can end in an explosion of the cell, or the pressure that is created is often reduced by fire through a pressure relief valve (a rupture disc).
  • a pressure relief valve a rupture disc
  • the separator according to the invention which has inorganic components and a polymeric carrier material
  • meltdown there is no so-called meltdown in the separator according to the invention.
  • the separator according to the invention thus meets the requirements for a safety shutdown required by various battery manufacturers due to the shutdown in the battery cells.
  • the inorganic particles ensure that there can never be a meltdown. This ensures that there are no operating states in which a large-scale short circuit can occur.
  • an additional shutdown mechanism is absolutely necessary for the application, this can also be achieved, for example, by equipping the surface and / or the pores of the ceramic or hybrid separator according to the invention with a substance which, when the temperature limit is reached Closes pores and prevents further ion flow.
  • a substance which, when the temperature limit is reached Closes pores and prevents further ion flow.
  • This can be achieved, for example, by a polymer or a wax, the melting point of which is in this range.
  • the separator according to the invention is very safe.
  • the polymer separator would melt at the point of penetration (a short-circuit current flows over the nail and heats it up) and contract.
  • the short circuit point becomes larger and the reaction gets out of control.
  • the hybrid separator according to the invention at most the polymeric substrate material melts, but not the inorganic separator material.
  • the reaction inside the battery cell after such an accident is much more moderate. This battery is therefore significantly safer than one with a polymer separator. This is particularly important in the mobile area.
  • hybrid separator Another not inconsiderable advantage of the hybrid separator according to the invention is the very good wettability. Due to the hydrophilic ceramic coating, wetting with common electrolytes such as ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC) takes place very quickly. With less hydrophilic electrolytes, the surface can also be made more hydrophobic. This ensures fast, and thus also inexpensive, battery production with this separator.
  • electrolytes such as ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC)
  • the separator according to the invention has a clear price advantage compared to separators based on glass or ceramic fabrics, such as z. B. be described in DE 101 42 622.
  • this is partly due to the fact that the polymer substrate is much easier to handle than glass or ceramic fabric, which nevertheless has a certain brittleness and is destroyed when handled carelessly. The entire manufacturing process is therefore more complex and therefore more expensive.
  • the width of the separator is sometimes reduced by up to 50% or even 70% compared to the starting material used as the substrate.
  • the waves in the separator frequently cause kinks and / or folds, and thus breakages and holes in the material, so that it can no longer be used for its intended purpose but must be discarded as rejects.
  • Another problem is that the coating is detached from the substrate on cooling, since the coating material shrinks less on cooling than the carrier material and therefore breaks off easily.
  • a coating can nevertheless be carried out on the machines suitable for the production of membranes based on glass or metal fabrics if special machine parameters are observed, in particular if the substrate has a maximum longitudinal clamping force of less than during the coating process 10 N / cm is exposed.
  • the method is particularly preferably changed in such a way that an auxiliary device, a so-called clamping frame, is used during the coating process and the temperature is chosen such that it is always 20 ° C. below the softening temperature of the polymer.
  • the method according to the invention for the continuous production of a separator comprising a flat, multi-aperture, flexible substrate with a porous, inorganic, electrically insulating coating located on and in this substrate, the material of the substrate being selected from non-woven, non-electrical conductive polymer fibers and the substrate has a porosity of greater than 50%, in which the substrate is unwound from a roll, undergoes a coating process in which the substrate is provided with the coating, and the finished separator on one second roll is characterized in that the substrate is guided during the coating process in such a way that it has a maximum longitudinal tension of 10 N / cm and undergoes a temperature treatment.
  • the material of the substrate is selected from non-woven polymer fibers.
  • Nonwoven polymer fibers can e.g. B. knitted fabrics, fleeces or felts.
  • a nonwoven made of polymer fibers or a nonwoven having polymer fibers is particularly preferably used as the flexible substrate.
  • a fleece preferably a very thin and homogeneous fleece material, a uniform resistance is achieved in the application with an electrolyte.
  • Nonwovens have the advantage that they have a significantly higher porosity than comparable fabrics.
  • the substrate used preferably has a porosity of 50 to 97%, particularly preferably 50 to 90% and very particularly preferably 60 to 90%.
  • the porosity is defined as the volume of the fleece (100%) minus the volume of the fibers of the fleece, that is the proportion of the volume of the fleece that is not filled by material.
  • the volume of the fleece can be calculated from the dimensions of the fleece.
  • the volume of the fibers results from the measured weight of the fleece under consideration and the density of the polymer fibers.
  • the large porosity of the substrate also enables a higher porosity of the hybrid separator according to the invention, which is why a higher absorption of electrolytes can be achieved with the separator according to the invention.
  • the material of the substrate is particularly preferably selected from nonwovens of polymer fibers with a thickness of the fibers of 0.1 to 10 ⁇ m. It can be particularly advantageous if the separator according to the invention has a substrate which has a thickness of 5 to 30 ⁇ m, preferably 10 to 20 ⁇ m. The thickness of the substrate has a great influence on the properties of the separator, since on the one hand the flexibility but also the surface resistance of the separator impregnated with electrolyte depends on the thickness of the substrate. In addition, thinner separators allow an increased packing density in a battery stack, so that a larger amount of energy can be stored in the same volume.
  • Substrate preferably non-electrically conductive fibers of polymers, which are preferably selected from polyacrylonitrile (PAN), polyester, such as. B. polyethylene terephthalate (PET) and / or polyolefin (PO), such as. B. polypropylene (PP) or polyethylene (PE) or mixtures of such polyolefins. All other polymers stable in the very reactive media of the batteries can also be used, but the above-mentioned are particularly preferred materials.
  • the substrate used preferably has polymer fibers which have a softening temperature of greater than 100 ° C. and a melting temperature of greater than 110 ° C. It can be advantageous if the polymer fibers have a diameter of 0.1 to 10 ⁇ m, preferably 1 to 5 ⁇ m.
  • the coating is applied to and into the substrate by applying a suspension and heating at least once, during which the suspension is solidified on and in the substrate, the suspension at least one oxide which is not or only poorly conductive, preferably the elements Al, Zr and / or Si and a sol.
  • the method itself is known from WO 99/15262, but not all parameters or feedstocks, in particular feedstocks which are not electrically conductive, can be used for the production of the separator according to the invention.
  • the selection of the input materials also results in certain process parameters that had to be found for the material combinations suitable as separators.
  • the suspension can e.g. B. by printing, pressing, pressing, rolling, knife coating, spreading, dipping, spraying or pouring onto and into the substrate.
  • the suspension used to produce the coating has at least one sol of the elements Zr, Al and / or Si or a mixture of these sols, and is produced by suspending at least one inorganic component in at least one of these sols. It can be advantageous if, in order to produce the suspension as an inorganic component, at least one oxide selected from the oxides of the elements Zr, Al and Si is suspended in a sol.
  • the mass fraction of the suspended component is preferably 1 to 250 times, particularly preferably 1 to 50 times the sol used.
  • the suspended component preferably has average grain sizes from 20 to 10,000 nm or average particle sizes of the primary particles from 5 to 10,000 nm.
  • the sols are obtained by hydrolyzing at least one compound of the above elements with water or an acid or a combination of these compounds.
  • the compound to be hydrolyzed may also be advantageous to add the compound to be hydrolyzed to alcohol or an acid or a combination of these liquids before the hydrolysis.
  • the compound to be hydrolyzed at least one nitrate, one halide, one chloride, one carbonate or one alcoholate compound is preferably hydrolyzed.
  • An alcoholate compound of the elements Zr, Al and / or Si is preferably hydrolyzed as the alcoholate compound.
  • the hydrolysis is preferably carried out in the presence of water, steam, ice or an acid or a combination of these compounds.
  • particulate sols are produced by hydrolysis of the compounds to be hydrolyzed. These particulate sols are characterized by the fact that the compounds formed in the sol by hydrolysis are present in particulate form.
  • the particulate sols can be prepared as described above or as described in WO 99/15262. These brines usually have a very high water content, which is preferably greater than 50% by weight. It may be advantageous to add the compound to be hydrolyzed to alcohol or an acid or a combination of these liquids before the hydrolysis.
  • the hydrolyzed compound can be treated with at least one organic or inorganic acid, preferably with a 10 to 60% organic or inorganic acid, particularly preferably with a mineral acid selected from sulfuric acid, hydrochloric acid, perchloric acid, phosphoric acid and nitric acid or a mixture of these acids become.
  • the particulate sols produced in this way can then be used for the production of suspensions, the production of suspensions for application to polymer fiber webs pretreated with polymer sol being preferred.
  • polymeric sols are produced by hydrolysis of the compounds to be hydrolyzed.
  • the sol has a water and / or acid content of less than 50% by weight.
  • These polymeric sols are distinguished by the fact that the compounds formed in the sol by hydrolysis are polymeric (ie chain-like crosslinked over a larger space).
  • the polymeric sols have usually less than 50% by weight, preferably very much less than 20% by weight, of water and / or aqueous acid.
  • the hydrolysis is preferably carried out in such a way that the compound to be hydrolyzed with the 0.5 to 10 times molar ratio and preferably with half the molar ratio of water, steam or ice, based on the hydrousable group, the hydrolyzable compound, is hydrolyzed.
  • up to 10 times the amount of water can be used with very slow hydrolyzing compounds such.
  • B. be used in tetraethoxysilane.
  • Very rapidly hydrolyzing compounds such as zirconium tetraethylate can already form particulate sols under these conditions, which is why 0.5 times the amount of water is preferably used for the hydrolysis of such compounds.
  • the compound to be hydrolyzed is dissolved in an organic solvent, in particular ethanol, isopropanol, butanol, amyl alcohol, hexane, cyclohexane, ethyl acetate and or mixtures of these compounds, before the actual hydrolysis is carried out.
  • an organic solvent in particular ethanol, isopropanol, butanol, amyl alcohol, hexane, cyclohexane, ethyl acetate and or mixtures of these compounds.
  • a sol produced in this way can be used to produce the suspension according to the invention.
  • Both particulate sols and polymeric sols can be used as sol in the process according to the invention for producing the suspension.
  • commercially available brines such as e.g. B. zirconium nitrate sol or silica sol can be used.
  • the method of producing separators by applying and solidifying a suspension to a carrier in and of itself is known from DE 101 42 622 and in a similar form from WO 99/15262, but not all parameters or feedstocks can be used to produce the transferred membrane of the invention.
  • the process described in WO 99/15262 in particular, cannot be transferred in this form to polymeric nonwoven materials without compromises.
  • the suspensions adhesion promoters used such as. B. add organofunctional silanes.
  • organofunctional silanes compounds selected from the octylsilanes, the vinylsilanes, the amine-functionalized silanes and / or the glycidyl-functionalized silanes, such as, for. B. the Dynasilane from Degussa can be used.
  • adhesion promoters for polyethylene (PE) and polypropylene (PP) are vinyl, methyl and octylsilanes, the exclusive use of methylsilanes not being optimal, for polyamides and polyamines it is amine-functional silanes, for polyacrylates and polyesters it is glycidyl-functionalized Silanes and, for polyacrylonitrile, glycidyl-functionalized silanes can also be used.
  • Other adhesion promoters can also be used, but these have to be matched to the respective polymers.
  • the adhesion promoters must be selected so that the solidification temperature is below the melting or softening point of the polymer used as the substrate and below its decomposition temperature.
  • Suspensions according to the invention preferably have very much less than 25% by weight, preferably less than 10% by weight, of compounds which can act as adhesion promoters.
  • An optimal proportion of adhesion promoter results from the coating of the fibers and / or particles with a monomolecular layer of the adhesion promoter.
  • the amount of adhesion promoter required in grams can be obtained by multiplying the amount of oxides or fibers used (in g) by the specific surface area of the materials (in m 2 g _1 ) and then dividing by the specific space requirement of the adhesion promoter (in m 2 g "1 ) can be obtained, the specific space requirement often being in the order of 300 to 400 m 2 g " 1 .
  • Table 1 below contains an exemplary overview of adhesion promoters that can be used based on organofunctional Si compounds for typical polymers used as nonwoven material.
  • AMEO 3-aminopropyltriethoxysilane
  • DAMO 2-aminoethyl-3-aminopropyltrimethoxysilane
  • GLYMO 3-glycidyloxytrimethoxysilane
  • MEMO 3-methacryloxypropyltrimethoxysilane
  • VTEO vinyl triethoxysilane
  • VTMO vinyl trimethoxysilane
  • VTMOEO vinyl tris (2-methoxyethoxy) silane
  • the abovementioned adhesion promoters are applied to the substrate, in particular the polymer fleece, in an upstream step.
  • the adhesion promoter in a suitable solvent, such as. B. dissolved ethanol.
  • This solution can also contain a small amount of water, preferably 0.5 to 10 times the amount based on the molar amount of the hydrolyzable group, and small amounts of an acid, such as. B. HC1 or HNO 3 , as a catalyst for the hydrolysis and condensation of the Si-OR groups.
  • a suitable solvent such as. B. dissolved ethanol.
  • This solution can also contain a small amount of water, preferably 0.5 to 10 times the amount based on the molar amount of the hydrolyzable group, and small amounts of an acid, such as. B. HC1 or HNO 3 , as a catalyst for the hydrolysis and condensation of the Si-OR groups.
  • this solution is applied to the substrate and the adhesion promoter is fixed by a temperature treatment at 50 to a maximum of 350 ° C. on the substrate.
  • the suspension is applied and solidified only after the adhesion promoter has been applied.
  • the adhesion behavior of the substrates can be improved, in particular in relation to aqueous, particulate sols, which is why substrates pretreated in this way have suspensions in particular
  • the coatings according to the invention are applied to the substrate by solidifying the suspension in and on the substrate.
  • the suspension present on and in the substrate can be solidified by heating to 50 to 350 ° C. Since the maximum temperature is determined by the substrate when using polymeric substrate materials, this must be adjusted accordingly.
  • the suspension present on and in the substrate is solidified by heating to 100 to 350 ° C. and very particularly preferably by heating to 110 to 280 ° C. It can be advantageous if the heating is carried out for 1 second to 60 minutes at a temperature of 100 to 350 ° C.
  • the suspension is particularly preferably heated for solidification to a temperature of 110 to 300 ° C., very particularly preferably at a temperature of 110 to 280 ° C. and preferably for 0.5 to 10 minutes.
  • the heating that is to say the temperature treatment, is carried out in particular at a temperature which is at least 20 ° C. below the softening temperature of the polymer material.
  • the inventive heating of the composite can be done by means of heated air, hot air, infrared radiation or by other heating methods according to the prior art respectively.
  • the continuous process according to the invention is preferably carried out in such a way that the substrate is unwound from a roll at a speed of 1 m / h to 2 m / s, preferably at a speed of 0.5 m / min. up to 20 m / min. and very particularly preferably at a speed of 1 m / min to 5 m / min through at least one apparatus which brings the suspension onto and into the support, such as. B. a roller, and at least one other apparatus that allows the solidification of the suspension on and in the support by heating, such as. B. passes through an electrically heated oven and the separator thus produced is rolled up on a second roll.
  • the pre-treatment steps can also be carried out in a continuous process while maintaining the parameters mentioned.
  • the method must be carried out such that the substrate has a maximum longitudinal stress of 10 N / cm, preferably a maximum of 3 N / cm and particularly preferably a maximum of 0 during the coating process or the coating processes, in particular during the heat treatment (drying) , 1 N / cm.
  • Coating processes are understood to mean all process steps in which a material is brought onto and into the substrate and is solidified there by heat treatment.
  • the substrate is preferably stretched during the coating process with a maximum force of 0.001 to 3 N / cm. It can be particularly preferred if the substrate is guided in the longitudinal direction almost without tension during the coating process or the coating processes.
  • the tension must be checked very precisely so that there is no deformation (also no elastic) of the carrier material. Due to possible deformation (elongation) when the tensile stress is too high, the ceramic coating cannot follow the material, which leads to the coating becoming detached from the substrate material over the entire surface. The resulting product cannot then be used as intended. Without observing the stated limit, coating a polymeric substrate material with a porous ceramic is not feasible.
  • the rollers or rollers are preferably equipped with a drive, wherein the speed of rotation can preferably be controlled separately for both rollers or rollers. There may be additional roles between these two roles or rollers. These do not necessarily have to be driven, but can be designed as pure support rollers as very smoothly running rollers or rollers. However, it can also be advantageous to equip these roles with one drive each and separately controllable.
  • the rollers can be arranged so that the substrate is guided vertically, horizontally or at any other angle in relation to the force of gravity.
  • the substrate is preferably guided vertically or horizontally. Both types of leadership have certain advantages or disadvantages.
  • the substrate When the substrate is guided vertically during the application and application of the coating material and the subsequent solidification of the material, the substrate cannot sag between two rollers and thus lead to an uncontrolled expansion of the material when the coating material is applied.
  • the method according to the invention is carried out in such a way that the substrate is guided in a spa frame during the coating process, in particular during the heat treatment.
  • the stenter has lateral guides that guide the substrate during the coating process.
  • the guidance in the tentering frame also means that a normal shrinkage of the web during temperature treatment is only noticeable in the thickness of the web, but not in the surface dimensions of the material.
  • the tensioning frame particularly preferably has lateral guides which have movable aids and which are preferably provided with are equipped with an adjustable drive. The movable aids preferably engage or clamp the substrate and can be moved at a selectable speed.
  • a possible embodiment of such a clamping frame consists of two driven rollers or rollers, the speed of which can be regulated. Between the rollers there are chains or belts on one or both ends of the rollers which rotate at the speed of the rollers.
  • the chains or belts have aids at regular intervals that can engage in the substrate.
  • Such tools can e.g. B. (short) needles, clamps or similar devices that are suitable to intervene in the substrate.
  • the aids engage in the substrate at a distance of 0.2 to 2 cm from the edge of the substrate web.
  • auxiliary means intervene evenly distributed on the sides of the substrate This can be achieved by the auxiliary means engaging the substrate continuously or at uniform intervals, the intervals being able to be from 0 (continuous) to 15 cm, preferably from 1 to 10 cm.
  • the defective edge areas caused by the stenter frame are continuously cut off directly before the separator is wound up. This is done either with fixed blades or with rotating knives.
  • the surfaces of the knives are preferably made of hardened steel or are made with a very hard material, such as. B. diamond coated so that they do not become dull in a short time when cutting the ceramic separator and can no longer cut the separator clean.
  • the use of several knives also has the advantage that the separators can be manufactured in a large width of over 50 cm and, before being wound up from this wide web, tailored strips of a few centimeters, which are completely sufficient for many types of batteries, depending on the customer's requirements , can be cut. This makes the process more cost-effective than subsequent assembly.
  • Separators can be produced by means of the method according to the invention, which in particular for Use as a separator in a battery.
  • the separators produced using the method according to the invention preferably have thicknesses of less than 35 ⁇ m, preferably less than 25 ⁇ m and very particularly preferably from 10 to 25 ⁇ m.
  • the low thickness results in a particularly low electrical resistance of the separator when used with an electrolyte.
  • the separator itself of course, has a very high electrical resistance, since it must itself have insulating properties.
  • the separator according to the invention has a porous, electrically insulating, ceramic coating. It can be advantageous if the coating on and in the substrate has a non-electrically conductive oxide of the metals Al, Zr or Si.
  • the separator preferably has a porosity of 30% to 80%, particularly preferably 50 to 70%.
  • the porosity relates to the attainable, i.e. open, pores.
  • the porosity can be determined using the known method of mercury porosimetry or can be calculated from the volume and density of the feedstocks used if it is assumed that only open pores are present.
  • the separators according to the invention are distinguished by the fact that they can have a tear strength of at least 1 N / cm, preferably at least 3 N / cm and very particularly preferably from 3 to 10 N / cm.
  • the separators according to the invention can preferably be bent down to any radius down to 100 m, preferably down to 50 mm and very particularly preferably down to 2 mm without damage.
  • the high tensile strength and the good bendability of the separator according to the invention has the advantage that changes in the geometries of the electrodes which occur during charging and discharging of a battery can be carried out by the separator without the latter being damaged.
  • the flexibility also has the advantage that this separator can be used to produce commercially standardized winding cells.
  • the electrode / separator layers are wound up in a spiral in standardized size and contacted.
  • the separators according to the invention can be used up to a temperature which corresponds to the shutdown temperature (switch-off temperature), that is to say the melting temperature of the substrate or possibly additionally applied shutdown particles.
  • a separator manufactured according to the invention can be used in all conventional batteries, especially primary and secondary batteries are used. To use the separator according to the invention, it is usually filled with a suitable electrolyte system, so that ion migration through the separator from one electrode of the battery to the other is possible. After the separator according to the invention has been filled with an electrolyte which has lithium ions, it can be used, for example, in a lithium-ion battery as a separator.
  • the invention also relates to batteries which have a separator according to the invention.
  • batteries can e.g. B. a lithium-ion battery, a nickel metal hydride battery, a nickel-cadmium battery, a silver-zinc battery or a zinc-air battery.
  • a battery is particularly preferably a lithium-ion battery.
  • the separators according to the invention are well suited for use in batteries which are to be charged quickly. Due to the high temperature resistance of the separator according to the invention, a battery which is equipped with this separator is not as temperature-sensitive and can therefore tolerate the temperature rise due to the rapid charging without negative changes in the separator or without damage to the battery.
  • the slip is rolled onto the fleece with a roller that moves parallel to the direction of the belt (direction of movement of the fleece).
  • the fleece then runs through a convection oven which has the specified temperature.
  • the web tension between unwinder and coating is approx. 10 N, the web tension between coating and winding is approx. 30 N.
  • This slip is homogenized for at least a further 24 h using a magnetic stirrer, the stirring vessel having to be covered so that there is no loss of solvent.
  • a separator with an average pore size of 240 nm is obtained at the end.
  • Example 3 Preparation of an S450PO separator First, 15 g of a 5% strength by weight aqueous HCl solution, 10 g of tetraethoxysilane, 2.5 g of methyltriethoxysilane and 7.5 g of Dynasilane GLYMO are added to 160 g of ethanol. In this sol, which was initially stirred for a few hours, 125 g of each Suspended aluminum oxides Martoxid MZS-1 and Martoxid MZS-3. This slip is homogenized for at least a further 24 h using a magnetic stirrer, the stirring vessel having to be covered so that there is no loss of solvent.
  • the tenter frame is needled to the left and right of the fleece in front of the furnace and needled again after the furnace.
  • the perforated edge areas are cut with rotating knives before winding.
  • a separator with an average pore size of 100 nm is obtained.
  • Example 6 Preparation of an S450PAN separator First, 15 g of a 5% strength by weight aqueous HCl solution, 10 g of tetraethoxysilane, 2.5 g of methyltriethoxysilane and 7.5 g of Dynasilane MEMO are added to 160 g of ethanol. 140 g of the aluminum oxides Martoxid MZS-1 and Martoxid MZS-3 are then suspended in this sol, which was initially stirred for a few hours. This slip is homogenized for at least a further 24 h using a magnetic stirrer, the stirring vessel having to be covered so that there is no loss of solvent.
  • a separator with an average pore size of 450 nm is obtained, which has a better adhesive strength of the coating than the coating on the separator according to Example 2.
  • Example 7 Preparation of an S450PET separator First, 30 g of a 5% strength by weight aqueous HNO 3 solution, 10 g of tetraethoxysilane, 2.5 g of methyltriethoxysilane and 7.5 g of dynasilane GLYMO are added to 130 g of water and 30 g of ethanol given. 125 g of the aluminum oxides Martoxid MZS-1 and Martoxid MZS-3 are then suspended in this sol, which was initially stirred for a few hours. This slip is homogenized for at least a further 24 h using a magnetic stirrer, the stirring vessel having to be covered so that there is no loss of solvent.
  • a separator with an average pore size of 450 nm is obtained, which has a very good adhesive strength and a smaller thickness of now approx. 30 ⁇ m than the separator described in Example 1.
  • a separator with an average pore size of 450 nm is obtained, which has very good adhesive strength and is very stable even in very alkaline media (pH> 10).
  • Example 10 Alkaline cell with a ZZ240PAN
  • 1.4 g of zirconium acetylacetonate are dissolved in a mixture of 150 g of deionized water and 22.5 g of ethanol.
  • 280 g of the zirconium oxide SCI 05 are suspended in this solution and the slip is stirred for at least 24 h.
  • another 75 g of a commercial 30% by weight zirconium nitrate sol (MEL Chemicals) are added to the slip.
  • a separator with an average pore size of 450 nm is obtained, which has very good adhesive strength and is very stable even in very alkaline media (pH> 10).
  • This separator can therefore be used very well in Ni / MeH or Ag / Zn batteries. These cells have a long-term stability of at least 100 charging cycles.
  • Example 11 Li-ion battery with hybrid ceramic separator
  • a S450PET separator produced according to Example 7 is made into a Li-ion cell consisting of a positive mass as LiCoO 2 , a negative mass consisting of graphite and an electrolyte LiPF ⁇ in ethylene carbonate / dimethyl carbonate, built-in [LiCoO2 // S-450-PET, EC / DMC 1: 1, IM LiPF6 // graphite].
  • LiCoO2 // S-450-PET, EC / DMC 1: 1, IM LiPF6 // graphite The charging behavior of this battery was checked. After more than 250 cycles, the battery shows only a slight decrease in capacity by a few percentage points. An increase in the charging voltage from 4.1 to 4.2 volts in the 200th charging cycle does not harm the battery.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Cell Separators (AREA)

Abstract

L'invention concerne un procédé permettant de produire des séparateurs, notamment des séparateurs électriques, ainsi que les séparateurs en tant que tels. Un séparateur électrique est un séparateur utilisé dans des batteries et d'autres systèmes, dans lesquels des électrodes, par ex. avec maintien de la conductivité des ions, doivent être séparées. Ledit séparateur est de préférence une substance isolante, mince et poreuse, à haute perméabilité aux ions, présentant une bonne résistance mécanique et une bonne stabilité à long terme, vis-à-vis de produits chimiques et de solvants utilisés dans le système, par ex. dans les électrodes d'une batterie. Le séparateur doit isoler entièrement sur le plan électrique la cathode de l'anode, dans des batteries. Le séparateur doit en outre avoir une élasticité continue et suivre les mouvements intervenant dans le système, par ex. dans le paquet d'électrodes, au moment de la charge et de la décharge. A cet effet, il est prévu d'utiliser le procédé suivant, selon lequel un substrat est muni d'un revêtement céramique poreux. Le processus de revêtement est régulé de sorte que le substrat soit guidé avec une tension maximale dans le sens longitudinal de 10 N/cm. Cette mesure permet audit revêtement d'avoir une durabilité nettement supérieure à celle de séparateurs produits selon des procédés classiques, étant donné qu'une déformation, notamment une déformation élastique ou plastique et un retrait du matériau constituant le substrat sont évités dans une large mesure.
PCT/EP2003/007155 2002-08-24 2003-07-04 Procede de production d'un separateur, notamment pour batteries ions-lithium WO2004021474A1 (fr)

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DE10238940A DE10238940A1 (de) 2002-08-24 2002-08-24 Verfahren zur Herstellung eines Separators, insbesondere für Lithium-Ionen-Batterien
DE10238940.3 2002-08-24

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Cited By (2)

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Publication number Priority date Publication date Assignee Title
US7960061B2 (en) 2004-04-20 2011-06-14 Degussa Ag Electrolyte composition in addition to the use thereof as an electrolyte material for electrochemical energy storage systems
US9214659B2 (en) 2004-04-20 2015-12-15 Evonik Degussa Gmbh Use of a ceramic separator in lithium ion batteries, comprising an electrolyte containing ionic fluids

Families Citing this family (3)

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Publication number Priority date Publication date Assignee Title
EP1626109A1 (fr) * 2004-08-11 2006-02-15 "VLAAMSE INSTELLING VOOR TECHNOLOGISCH ONDERZOEK", afgekort "V.I.T.O." Séparateur renforcé par un tissu et méthode de production en continu.
DE102009032050A1 (de) * 2009-07-07 2011-01-27 Li-Tec Battery Gmbh Sekundärbatterie mit Schnellladefähigkeit
DE102013200722A1 (de) 2012-01-30 2013-08-01 Evonik Litarion Gmbh Separator enthaltend eine organisch-anorganische Haftvermittlerkomponente

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US4707265A (en) * 1981-12-18 1987-11-17 Cuno Incorporated Reinforced microporous membrane
WO1999015262A1 (fr) * 1997-09-20 1999-04-01 Creavis Gesellschaft Für Technologie Und Innovation Mbh Materiau composite permeable a la matiere, son procede de fabrication et son utilisation
DE19918856A1 (de) * 1998-04-27 1999-11-11 Sumitomo Chemical Co Trennelement für Batterien mit nichtwäßrigem Elektrolyt
US6090441A (en) * 1998-03-18 2000-07-18 Cuno, Inc. Process of making reinforced, three zone microporous membrane

Patent Citations (4)

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US4707265A (en) * 1981-12-18 1987-11-17 Cuno Incorporated Reinforced microporous membrane
WO1999015262A1 (fr) * 1997-09-20 1999-04-01 Creavis Gesellschaft Für Technologie Und Innovation Mbh Materiau composite permeable a la matiere, son procede de fabrication et son utilisation
US6090441A (en) * 1998-03-18 2000-07-18 Cuno, Inc. Process of making reinforced, three zone microporous membrane
DE19918856A1 (de) * 1998-04-27 1999-11-11 Sumitomo Chemical Co Trennelement für Batterien mit nichtwäßrigem Elektrolyt

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7960061B2 (en) 2004-04-20 2011-06-14 Degussa Ag Electrolyte composition in addition to the use thereof as an electrolyte material for electrochemical energy storage systems
US9214659B2 (en) 2004-04-20 2015-12-15 Evonik Degussa Gmbh Use of a ceramic separator in lithium ion batteries, comprising an electrolyte containing ionic fluids

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TW200405602A (en) 2004-04-01
DE10238940A1 (de) 2004-03-04
AU2003249954A1 (en) 2004-03-19

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