WO2013020661A1

WO2013020661A1 - Lithium ion battery and method for producing a lithium ion battery

Info

Publication number: WO2013020661A1
Application number: PCT/EP2012/003183
Authority: WO
Inventors: Tim Schaefer
Original assignee: Li-Tec Battery Gmbh
Priority date: 2011-08-09
Filing date: 2012-07-26
Publication date: 2013-02-14
Also published as: DE102011109813A1

Abstract

The invention relates to a lithium ion battery which comprises: at least one positive electrode; one negative electrode; one separator which separates the electrodes from each other; and one electrolyte, characterized in that the positive or negative electrode comprises, or the positive and the negative electrode comprise a styrene-butadiene rubber (SBR), and the separator comprises a preferably non-interwoven mat made of polymer fibers, which is coated on one or on both sides with an inorganic material that is conductive for lithium ions.

Description

Lithium ion battery and

Process for producing a lithium ion battery

Hereby, the entire content of the priority application DE 10 2011 109 813.9 by reference is part of the present application.

The present invention relates to an electrochemical cell, preferably a rechargeable lithium ion battery, which has high stability and safety. The invention further relates to a method for producing the electrochemical cell and its use.

Rechargeable lithium ion batteries can be manufactured by laminating film-like electrodes formed as cathode and anode and a film-like separator located between the electrodes. To increase performance, such laminates are interconnected and / or stacked and / or wound (for many applications, such as hybrid or pure electric vehicles or stationary storage, it is necessary that the batteries or cells, stacks or Winding against short circuits and burning through and / or against mechanical damage, in particular the electrodes are protected, ie they must have a high stability and safety.

The object of the present invention is to provide an electrochemical cell, preferably a rechargeable lithium-ion battery, which has high stability and safety. This object is achieved with a rechargeable electrochemical cell according to claim 1. Advantageous developments are defined in the subclaims. According to a first aspect, the invention relates to an electrochemical cell, preferably a lithium ion battery, comprising at least: a positive electrode; a negative electrode; a separator which separates the electrodes from each other; an electrolyte; characterized in that the positive or negative electrode or the positive and negative electrodes comprise a styrene-butadiene rubber (SBR); and

the separator comprises a preferably non-woven web which is coated on one or both sides with an inorganic material which is conductive for lithium ions.

The electrochemical cell of the present invention has the advantage that particularly stable and safe batteries can be obtained by using the separator in combination with a positive or negative electrode or a positive and negative electrode containing a styrene-butadiene rubber protected against short circuits and burn-through and / or against mechanical damage, in particular of the electrodes. Because of its high stability and safety, the electrochemical cell according to the invention can therefore be used advantageously in vehicles with hybrid drive or electric drive as well as in stationary storage systems.

The terms used below are defined within the meaning of the invention. Battehe

The terms "lithium ion battery", "rechargeable lithium ion battery" and "lithium ion secondary battery" are used synonymously. The terms also include the terms "lithium battery", "lithium ion secondary battery" and "lithium ion cell". Thus, the term "lithium ion battery" is used as a generic term for the conventional terms used in the prior art. It means both rechargeable batteries (secondary batteries) as well as non-rechargeable batteries (primary batteries). In particular, a "battery" in the context of the present invention also includes a single or single "electrochemical cell". Preferably, in a "battery" two or more such electrochemical cells are connected together, either in series (ie one behind the other) or in parallel.

Electrodes The electrochemical cell of the invention has at least two electrodes, i. a positive and a negative electrode.

In this case, both electrodes each have a material which can conduct lithium ions or intercalate lithium ions or metallic lithium.

The term "positive electrode" means the electrode that is capable of accepting electrons when the battery is connected to a consumer, such as an electric motor. It represents the cathode in this nomenclature.

The term "negative electrode" means the electrode that is capable of delivering electrons when in use. It represents the anode in this nomenclature.

The electrodes preferably comprise inorganic material or inorganic compounds or substances which are for or in or on an electrode or can be used as an electrode. These are preferably compounds or substances which, under the working conditions of the lithium ion battery, due to their chemical nature, conduct lithium ions or absorb (intercalate) lithium ions or metallic lithium and can also give it off again. In the prior art, such a material is also referred to as "active material" of the electrode. This material is preferably applied to a carrier for use in an electrochemical cell or battery, preferably a metallic carrier, preferably aluminum or copper. This carrier is also referred to as a "Abieiter" or as a "collector".

Positive electrode

As the active material for the positive electrode, there can be used any of materials known in the related art. Thus, there is no limitation with regard to the positive electrode in the sense of the present invention.

In one embodiment, as the positive electrode active material, lithium phosphates may be used, preferably the molecular formula LiXPO ₄ with X = Mn, Fe, Co or Ni, or combinations thereof.

Other suitable compounds are lithium manganate, preferably LiMn ₂ 0 ₄ , lithium cobaltate, preferably LiCo0 ₂ , lithium nickelate, preferably LiNi0 ₂ , or mixtures of two or more of these oxides, or their mixed oxides.

To increase the conductivity further compounds may be present in the active material, preferably carbon-containing compounds, or carbon, preferably in the form of Leitruß or graphite. The carbon can also be introduced in the form of carbon nanotubes. Such additives are preferably applied in an amount of 1 to 6 wt .-%, preferably 1 to 3 wt .-% based on the applied to the carrier mass of the positive electrode. The active material may also contain mixtures of two or more of the substances mentioned.

Negative electrode

Suitable materials for the negative electrode are selected from: lithium metal oxides such as lithium titanium oxide, carbonaceous materials, preferably graphite, synthetic graphite, graphene, carbon black, mesocarbon, doped carbon, fullerenes. As the electrode material for the negative electrode, niobium pentoxide, tin alloys, titanium dioxide, tin dioxide, silicon are also preferable. binder

The materials used for the positive or negative electrode, such as the active materials, are held together by one or more binders, which hold these materials on the electrode or on the Abieiter. According to the invention, at least one of these binders is a styrene-butadiene rubber (SBR). This styrene-butadiene rubber causes a high mechanical stability of the electrodes.

The term "styrene butadiene rubber (SBR)" means a polymer of styrene and butadiene Such products are commercially available and can be used as known binders for materials for electrodes, both positive and negative electrodes Commercially available products are preferably in the form of emulsions.

In one embodiment, the styrene-butadiene rubber has hydrophilic groups. By such hydrophilic groups, the cohesion within the active group and / or the binding to the carrier can be improved. Without being bound to any theory, it is believed by the inventors that the hydrophilic groups may form non-covalent bonds in the form of, for example, hydrogen bonding to the active materials and / or carrier used, thereby increasing the mechanical stability of the electrode.

Preferably, the styrene-butadiene rubber also has monomer units which have one or more groups, preferably hydrophilic groups selected from: carboxyl, carboxylic anhydride, nitrile, hydroxyl, mercapto, acetate, ether, ester, amide, amine and / or Halogen.

In a further embodiment, the styrene-butadiene rubber is also characterized in that it is polymerized with a monomer containing butadiene units and / or a monomer having styrene units.

By introducing such groups, a crosslinking can be brought about in the styrene-butadiene rubber, which leads to a particularly firm cohesion in the active material or to a particularly strong binding of the active material to the support.

In one embodiment, the styrene-butadiene rubber has a glass transition temperature in the range of 5 to 25 ° C, or a glass transition temperature that is below this range.

In a further embodiment, the styrene-butadiene rubber has an average molecular weight Mw of 10,000 to 1,000,000 g / mol (determined by gel permeation chromatography). In a further embodiment, the styrene-butadiene rubber has a glass transition temperature in the range of 5 to 25 ° C, or a glass transition temperature which is below this range, and an average molecular weight Mw of 10,000 to 1,000,000 g / mol (determined by gel permeation chromatography).

In a further embodiment, in addition to the styrene-butadiene rubber, further binders may be present in the active material of the electrode.

In one embodiment, this binder is a carboxymethylcellulose (CMC). The term "carboxymethylcellulose" in this case means both a carboxymethylcellulose which has carboxyl groups and also a carboxymethylcellulose whose carboxyl groups are wholly or partially present as carboxylate groups, preferably with sodium ions as counterions.As a result, the term "carboxymethylcellulose" also includes salts of carboxymethylcellulose , preferably a sodium salt of carboxymethylcellulose.

Preferred Carboxymethlycellu loose, in particular sodium salts of carboxymethylcelluloses, have a degree of etherification of 1 to 1, 5 on. Such carboxymethylcelluloses are particularly well suited, inter alia, due to their relatively good solubility in water for the preparation of the electrodes. Suitable products are known from the relevant prior art.

In a further embodiment, the electrodes may also comprise further binders selected from polyvinylidene fluoride, polyethylene oxide, polyethylene, polypropylene, polytetrafluoroethylene, polyacrylate, ethylene (propylene-diene monomer) copolymer (EPDM) and mixtures and copolymers thereof. The styrene-butadiene rubber or the styrene-butadiene rubber and the carboxymethyl cellulose or the styrene-butadiene rubber and optionally carboxymethyl cellulose and / or the other binders are preferably present in an amount of 1-5 wt .-%, based on the total amount of the active material used in the positive or negative electrode.

In a further embodiment, the electrodes may also contain silica, preferably for improving the adhesion properties between the electrodes and the electrolyte and / or for improving the conductivity of the electrodes. The silica is preferably fumed silica. It is preferably used in an amount of 0.1 to 4.5% by weight, based on the total amount of electrode material on the support, preferably in an amount of 0.5 to 3.5% by weight. separator

The electrochemical cell according to the invention comprises a material which separates the positive electrode and the negative electrode from each other. This material is permeable to lithium ions, so it conducts lithium ions, but is a non-conductor for electrons. Such materials used in lithium ion batteries are also referred to as separators.

In a preferred embodiment according to the present invention, polymers are used as separators. In one embodiment, the polymers are selected from the group consisting of: polyester, preferably polyethylene terephthalate or polybutylene terephthalate; Polyolefin, preferably polyethylene, polypropylene or polybutylene; polyacrylonitrile; polycarbonate; Polysulfone; polyether sulfone; polyvinylidene fluoride; polystyrene; polyetherimide; Polyether; Polyether ketone. The polymers have pores so that they are permeable to lithium ions. In a preferred embodiment according to the present invention, the separator comprises at least one polymer and at least one inorganic, preferably ion-conducting material, preferably selected from oxides, phosphates, silicates, titanates, sulfates, aluminosilicates, comprising at least one of the elements zirconium, aluminum, Lithium.

Said separator of the battery according to the invention comprises polymer fibers in the form of a nonwoven. Preferably, the web is unwoven. Instead of the term "unwoven", the term "non-woven" is used. The relevant technical literature also includes terms such as "non-woven fabrics" or "non-woven material". The term "nonwoven" is used synonymously with the term "nonwoven fabric." Nonwovens are known from the prior art and / or can be produced by the known processes, for example by spinning processes with subsequent solidification Preferably, the polymer fibers are selected from the group of polymers consisting of polyester, polyolefin, polyamide, polyacrylonitrile, polyimide, polyetherimide, polysulfone, polyamideimide, polyether, polyphenylene sulfide, aramid, or mixtures of two or more of these polymers Polyesters are, for example, polyethylene terephthalate and polybutylene terephthalate.

Polyolefins are, for example, polyethylene or polypropylene. Halogen-containing polyolefins such as polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl chloride are also usable. Polyamides are for example the known types PA 6.6 and PA 6.0, known under the brand names Perlon Nylon ^® and ^®.

Aramids are, for example meta-aramid and para-aramid, which are known under the brand names Nomex ^® and Kevlar ^®.

Polyamide are known for example under the trade name Kermel ^®. Preferred polymer fibers are polymer fibers of polyethylene terephthalates.

In a preferred embodiment, the separator comprises a nonwoven, which is coated on one or both sides with an inorganic material. The term "coating" also includes that the ionic conductive inorganic material may be located not only on one side or both sides of the web, but also within the web.

The ion-conducting inorganic material used for the coating is preferably at least one compound from the group of oxides, phosphates, sulfates, titanates, silicates, aluminosilicates at least one of zirconium, aluminum or lithium.

The ionically conductive inorganic material is preferably ion conducting in a temperature range of from -40 ° C to 200 ° C, i. ion-conducting for the lithium ions.

In one embodiment, a separator may be used, which consists of an at least partially permeable carrier, which is not or only poorly electron-conducting. This carrier is on at least one side coated with an inorganic material. As an at least partially permeable carrier an organic material is used, which is designed as a nonwoven, so from non-woven polymer fibers. The organic material is in the form of polymer fibers, preferably polymer fibers of polyethylene terephthalate (PET). The nonwoven fabric is coated with an inorganic ion-conducting material which is preferably ion-conducting in a temperature range of -40 ° C to 200 ° C. The inorganic ion-conducting material preferably has at least one compound from the group of oxides, phosphates, sulfates, titanates, silicates, aluminosilicates with at least one of the elements zirconium, aluminum, lithium, particularly preferably zirconium oxide. The inorganic ion-conducting material preferably has particles with a maximum diameter of less than 100 nm.

In a preferred embodiment, the ion-conducting material comprises zirconium oxide or the ion-conducting material consists of zirconium oxide.

Such a separator is marketed in Germany, for example, under the trade name "Separion ^®" by the company Evonik AG. Methods for producing such separators are known from the prior art, for example from EP 1 017 476 B1, WO 2004/021477 and WO 2004/021499.

In principle, too large pores and holes in separators used in secondary batteries can lead to an internal short circuit. The battery can then discharge itself very quickly in a dangerous reaction. In this case, such large electrical currents can occur that a closed battery cell can even explode in the worst case. For this reason, the separator can also be crucial for safety or lack of safety. safety of a lithium high-performance or lithium-high-energy battery.

Polymer separators generally prevent any charge transport above a certain temperature (the so-called "shut-down temperature", which is about 120 ° C.). This happens because at this temperature, the pore structure of the separator collapses and all pores are closed. The fact that no ions can be transported, the dangerous reaction that can lead to an explosion, comes to a standstill. However, if the cell continues to be heated due to external circumstances, the so-called "break-down temperature" is exceeded at approx. 150 to 180 ° C. From this temperature, the separator melts and contracts. In many places 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 with an explosion of the cell, or the resulting pressure must be reduced by a pressure relief valve (a rupture disk) often under fire phenomena. In the separator used in the battery according to the invention comprising a nonwoven made of non-woven polymer fibers and the inorganic coating, it can only come to shutdown (shutdown), when melted by the high temperature, the polymer structure of the carrier material and penetrates into the pores of the inorganic material and this thereby closing. On the other hand, the separator does not break down (collapse) since the inorganic particles ensure that complete melting of the separator can not occur. This ensures that there are no operating states in which a large-area short-circuit can occur. By the type of nonwoven used, which has a particularly suitable combination of thickness and porosity, separators can be produced that can meet the requirements for separators in high-performance batteries, especially lithium high-performance batteries. The simultaneous use of precisely matched in their particle size oxide particles to produce the porous (ceramic) coating a particularly high porosity of the final separator is achieved, the pores are still small enough to unwanted growth of "lithium Whis ern "through the separator to prevent.

Due to the high porosity of the separator, however, care must be taken to ensure that no or the least possible dead space is created in the pores. The separators which can be used for the battery according to the invention also have the advantage that the anions of the conductive salt partly adhere to the inorganic surfaces of the separator material, which leads to an improvement in the dissociation and thus to a better ion conductivity in the high-current range.

The separator which can be used for the battery according to the invention, comprising a flexible nonwoven with a porous inorganic coating on and in this nonwoven, wherein the material of the nonwoven fabric is selected from (preferably nonwoven) polymer fibers, is also characterized in that the nonwoven fabric has a thickness of less than 30 m, has a porosity of more than 50%, preferably from 50 to 97% and a pore radius distribution in which at least 50% of the pores have a pore radius of 75 to 150 pm.

The separator particularly preferably comprises a nonwoven which has a thickness of 5 to 30 μm, preferably a thickness of 10 to 20 μm. Especially Also important is a homogeneous distribution of pore radii in the web as indicated above. An even more homogeneous pore radius distribution in the nonwoven, in combination with optimally matched oxide particles of a certain size, leads to an optimized porosity of the separator.

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 sheet resistance of the electrolyte-impregnated separator depends on the thickness of the substrate. Due to the small thickness, a particularly low electrical resistance of the separator is achieved in the application with an electrolyte. The separator itself has a very high electrical resistance, since it itself must have insulating properties against electrons. In addition, thinner separators allow increased packing density in a battery pack so that one can store a larger amount of energy in the same volume.

Preferably, the nonwoven web has a porosity of 60 to 90%, more preferably 70 to 90%. The porosity is defined as the volume of the web (100%) minus the volume of the fibers of the web, ie the proportion of the volume of the web 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 considered and the density of the polymer fibers. The large porosity of the substrate also allows a higher porosity of the separator, which is why a higher uptake of electrolytes with the separator can be achieved.

In order to obtain a separator having insulating properties, as polymer fibers for the non-woven fabric, it preferably has non-electrically conductive fibers of polymers as defined above. These are preferably selected from the polymers listed above, preferably polyacid nitrile, polyester, such as. As polyethylene terephthalate and / or polyolefin, such as. As polypropylene or polyethylene, or mixtures of such polyolefins.

The polymer fibers of the nonwovens preferably have a diameter of 0.1 to 10 μιτι, more preferably from 1 to 4 μηι.

Particularly preferred flexible nonwovens have a basis weight of less than 20 g / m ² , preferably from 5 to 10 g / m ² . The separator preferably has a porous, electrically insulating, ceramic coating in the preferably non-woven nonwoven fabric. The porous inorganic coating on and in the nonwoven preferably has oxide particles of the elements Li, Al, Si and / or Zr with an average particle size of from 0.5 to 7 μm, preferably from 1 to 5 μm and very particularly preferably from 1 , 5 to 3 pm up. The separator particularly preferably has a porous inorganic coating on and in the nonwoven, the aluminum oxide particles having an average particle size of from 0.5 to 7 μm, preferably from 1 to 5 μm and very particularly preferably from 1.5 to 3 μm which are bonded to an oxide of the elements Zr or Si. In order to achieve the highest possible porosity, more than 50% by weight and more preferably more than 80% by weight of all particles are preferably within the abovementioned limits of average particle size. As already described above, the maximum particle size is preferably 1/3 to 1/5 and particularly preferably less than or equal to 1/10 of the thickness of the nonwoven used.

The nonwoven and ceramic coating separator preferably has a porosity of from 30 to 80%, preferably from 40 to 75% and particularly preferably from 45 to 70%. The porosity refers to the achievable, ie open pores. The porosity can be determined by the known method of mercury porosimetry or can from the volume and The density of the starting materials used are calculated if it is assumed that only open pores are present.

The separators used for the battery according to the invention are also distinguished by the fact that they can have a tensile strength of at least 1 N / cm, preferably of at least 3 N / cm and very particularly preferably of 3 to 10 N / cm. The separators can preferably be bent without damage to any radius down to 100 mm, preferably down to 50 mm and most preferably down to 1 mm. This also makes the separator operational in combination with wound electrodes.

The high tear strength and the good bendability of the separator also have the advantage that changes in the geometries of the electrodes occurring during charging and discharging of a battery can be made through the separator without the latter and the positive electrode having the styrene-butadiene rubber or negative electrode or positive electrode and negative electrode are damaged. This is extremely favorable for the stability and safety of the cell.

In one embodiment, it is possible to design the separator to have the shape of a concave or convex sponge or pad, or the shape of wires or a felt. This embodiment is well suited to compensate for volume changes in the battery. Corresponding preparation methods are known to the person skilled in the art.

In a further embodiment, the polymer fleece used in the separator comprises a further polymer. Preferably, this polymer is arranged between the separator and the positive electrode and / or the separator and the negative electrode, preferably in the form of a polymer layer. In one embodiment, the separator is coated with this polymer on one or both sides.

Said polymer may be in the form of a porous membrane, i. as a film, or in the form of a nonwoven, preferably in the form of a nonwoven fabric of non-woven polymer fibers.

These polymers are preferably selected from the group consisting of polyester, polyolefin, polyacrylonitrile, polycarbonate, polysulfone, polyethersulfone, polyvinylidene fluoride, polystyrene, polyetherimide.

Preferably, the further polymer is a polyolefin. Preferred polyolefins are polyethylene and polypropylene. The separator is preferably coated with one or more layers of the further polymer, preferably of the polyolefin, which is preferably also present as a nonwoven, that is to say as nonwoven polymer fibers.

Preferably, a nonwoven of polyethylene terephthalate is used in the separator, which is coated with one or more layers of the further polymer, preferably the polyolefin, which is preferably also present as a nonwoven, that is, as nonwoven polymer fibers.

Particular preference is given to a separator of the above-described type of separation which is coated with one or more layers of the further polymer, preferably of the polyolefin, which is preferably also present as a nonwoven, ie preferably as nonwoven polymer fibers.

The coating with the further polymer, preferably with the polyolefin, can be carried out by gluing, lamination, by a chemical reaction Welding or be achieved by a mechanical connection. Such polymer composites and processes for their preparation are known from EP 1 852 926. Preferably, the nonwovens usable in the separator are made of nanofibers of the polymers used, whereby nonwovens are formed which have a high porosity with formation of small pore diameters. Thus, both the risk of short-circuit reactions can be further reduced. The fiber diameters of the polyethylene terephthalate fleece are preferably larger than the fiber diameters of the further polymer fleece, preferably the polyolefin fleece, with which the separator is coated on one or both sides. Preferably, the nonwoven made of polyethylene terephthalate then has a higher pore diameter than the nonwoven, which is made of the other polymer.

The use of a polyolefin in addition to the polyethylene terephthalate ensures increased safety of the electrochemical cell, since in undesirable or excessive heating of the cell, the pores of the polyolefin contract and the charge transport through the separator is reduced or terminated. Should the temperature of the electrochemical cell increase to such an extent that the polyolefin begins to melt, the polyethylene terephthalate effectively counteracts the melting together of the separator and thus an uncontrolled destruction of the electrochemical cell. Electrolyte (lithium salt electrolyte)

The term "electrolyte" or "lithium salt electrolyte" preferably means a liquid and a conducting salt, Preferably, the liquid is a solvent for the conducting salt, and the electrolyte is then preferably in the form of an electrolyte solution.

Suitable solvents are preferably inert. Suitable solvents are preferably solvents such as ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, butyl methyl carbonate, ethyl propyl carbonate, dipropyl carbonate, cyclopentanones, sulfolanes, dimethylsulfoxide, 3-methyl-1,3-oxazolidin-2-one, γ-butyrolactone, 1, 2-diethoxymethane, tetrahydrofuran, 2-methyltetrahydrofuran, 1, 3-dioxolane, methyl acetate, ethyl acetate, nitromethane, 1, 3-propanesultone.

In one embodiment, ionic liquids may also be used as the solvent. Such "ionic liquids" contain only ions. Preferred cations which may in particular be alkylated are imidazolium, pyridinium, pyrrolidinium, guanidinium, uronium, thiuronium, piperidinium, morpholinium, sulfonium, ammonium and phosphonium cations. Examples of useful anions are halide, tetrafluoroborate, trifluoroacetate, triflate, hexafluorophosphate, phosphinate and tosylate anions.

Examples of ionic liquids which may be mentioned are: N-methyl-N-propyl piperidinium bis (trifluoromethylsulfonyl) imide, N-methyl-N-butylpyrrolidinium bis (trifluoromethylsulfonyl) imide, N-butyl-N trimethylammonium bis (trifluoromethylsulfonyl) imide, triethylsulfonium bis (trifluoromethylsulfonyl) imide, N, N-diethyl-N-methyl-N- (2-methoxyethyl) -ammonium bis (trifluoromethylsulfonyl) -imide.

Preferably, two or more of the above-mentioned liquids are used. Preferred conductive salts are lithium salts which have inert anions and which are preferably non-toxic. Suitable lithium salts are preferably lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium bis (trifluoro-methylsulfonylimide), lithium trifluoromethanesulfonate, lithium tris (trifluoro-methylsulfonyl) methide, lithium tetrafluoroborate, lithium perchlorate, lithium tetrachloroaluminate, lithium bisoxalatoborate, lithium difluorooxalatoborate and / or lithium chloride; and mixtures of one or more of these salts. In one embodiment, the separator is impregnated with the lithium salt electrolyte.

In one embodiment, the electrochemical cell according to the invention is characterized in that the separator comprises at least one of the above-defined polymers which contains the lithium salt electrolyte.

Embodiments in which the separator forms a polymer electrolyte together with the lithium salt electrolyte are also preferred. The term "polymer electrolyte" in one embodiment means a lithium salt dissolved in a polymer matrix or a gel electrolyte of a lithium salt which is dissolved in a solvent, to which an inert polymer is added. The polymer for the polymer matrix or the inert polymer are selected from the polymers used for separators as defined above. As lithium salts and liquids, the above-defined lithium salts and liquids can be used.

In one embodiment, a polymer electrolyte of a lithium salt and polyethylene oxide is used. According to a second aspect, the invention relates to a method for producing the electrochemical cell according to the invention.

The process according to the invention is characterized in that it comprises the step (i):

(i) laminating a positive and a negative electrode to a separator such that the separator separates the positive and negative electrodes, the positive or negative electrode or the positive and negative electrodes comprising a styrene-butadiene rubber (SBR ) exhibit; and the separator comprises a preferably non-woven web coated on one or both sides with an inorganic material which is conductive to lithium ions.

The lamination according to step (i) can be carried out by methods known in the art. First, the active material for the positive or the negative electrode or the positive and the negative electrode is preferably mixed with an aqueous emulsion of the styrene-butadiene rubber, optionally with the addition of carboxymethyl cellulose and / or further binder and / or the silica and / or or of conductivity additives. The resulting paste may then be applied by known methods to the appropriate support, which is preferably aluminum or copper, such as by brushing or knife coating. Subsequently, the positive and the negative electrodes are then laminated on a separator so as to be separated from each other by the separator. The applied paste is then dried, such as by drying at elevated temperature and / or by the action of infrared rays.

In one embodiment, the carriers are in sheet form, as is the separator. Thus, electrodes can be produced, which are also in film form. The laminating step according to step (i) is then carried out so that films are laminated on one another.

In one embodiment, the separator is impregnated with the electrolyte to contain the electrolyte.

According to a third aspect, the invention relates to the use of the battery according to the invention or the battery produced by the method according to the invention.

Preferably, the lithium battery according to the invention can be operated at ambient temperatures of -40 to +100 ° C.

Preferred discharge currents of a battery according to the invention are greater than 100 A, preferably greater than 200 A, preferably greater than 300 A, more preferably greater than 400 A.

The battery / electrochemical cell according to the invention can be used for supplying energy to mobile information devices, tools, electrically powered automobiles, hybrid-powered automobiles and stationary energy storage devices.

Claims

claims

Lithium ion battery, which has at least:

a positive electrode; a negative electrode; a separator which separates the electrodes from each other; an electrolyte;

characterized in that the positive or negative electrode or the positive and negative electrodes have a styrene-butadiene rubber (SBR); and the separator comprises a preferably nonwoven web of polymer fibers coated on one or both sides with an inorganic material which is conductive to lithium ions.

Lithium ion battery according to claim 1, characterized in that the styrene-butadiene rubber monomer units having one or more groups selected from: carboxyl, carboxylic anhydride, nitrile, hydroxyl, mercapto, ether, ester, amide, amine and / or halogen ,

Lithium ion battery according to claim 1 or 2, characterized in that the styrene-butadiene rubber is polymerized with a monomer containing butadiene units and / or a monomer having styrene units.

Lithium ion battery according to one of the preceding claims, characterized in that the styrene-butadiene rubber has a glass transition temperature in the range of 5 to 25 ° C and / or an average molecular weight Mw of 10,000 to 1,000,000 g / mol (determined by gel permeation chromatography).

A lithium-ion battery according to any one of the preceding claims, characterized in that the positive or negative electrode or the positive and negative electrodes have a carboxymethyl cellulose in addition to the styrene-butadiene rubber (SBR).

Lithium ion battery according to one of the preceding claims, characterized in that the styrene-butadiene rubber or the styrene-butadiene rubber and the carboxymethylcellulose in an amount of 1-5 wt .-% based on the total amount of in the positive or negative Electrode used active material.

Lithium ion battery according to one of the preceding claims, characterized in that the separator is not or only poorly electron-conducting, and consists of an at least partially permeable carrier, wherein the carrier is preferably coated on at least one side with an inorganic material, wherein at least partially preferably an organic material is used, which is preferably designed as a non-woven fabric, wherein the organic material preferably comprises a polymer, and more preferably a polyethylene terephthalate (PET), wherein the organic material is coated with an inorganic, preferably ion-conducting material, which more preferably in a temperature range of - 40 ° C to 200 ° C ion conducting, wherein the inorganic material preferably at least one compound selected from the group of oxides, phosphates, sulfates, titanates, silicates, aluminosilicates at least one of the elements Zr, Al, Li comprises, particularly preferably zirconium oxide, and wherein the inorganic, ion-conducting material preferably has particles with a largest diameter below 100 nm.

8. A method for producing a lithium-ion battery as defined in any one of the preceding claims, characterized in that it comprises the step (i):

Laminating a positive and a negative electrode on a separator such that the separator separates the positive and negative electrodes, the positive or negative electrode or the positive and negative electrodes comprising a styrene-butadiene rubber (SBR); and the separator comprises a preferably non-woven web coated on one or both sides with an inorganic material which is conductive to lithium ions.

The method of claim 8, wherein the electrodes and the separator are in the form of films.

Use of the lithium-ion battery according to any one of claims 1 to 7, or a lithium-ion battery manufactured according to claim 8 or 9, for supplying power to mobile information devices, tools, electrically powered automobiles, hybrid-powered automobiles and stationary energy storage devices.