Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
  • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
  • H01M10/0566—Liquid materials
  • H01M10/0567—Liquid materials characterised by the additives
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
  • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2300/00—Electrolytes
  • H01M2300/0017—Non-aqueous electrolytes
  • H01M2300/0025—Organic electrolyte
• • 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 reducing the electrical capacity loss of a rechargeable lithium ion battery in cyclic charging and discharging operation, wherein organic esters are added to the electrolyte of the battery. Further objects of the invention relate to the electrolyte of the battery as well as the battery containing the electrolyte.
• Secondary batteries in particular lithium ion secondary batteries, are used as energy stores for mobile information devices because of their high energy density and high capacity.
• secondary batteries are also used for tools, electrically powered automobiles and for hybrid cars.
• secondary batteries such as rechargeable lithium ion cells are subject to a decrease in the electric capacity or an increase in the internal resistance with the charge / discharge cycles.
• covering layers are made responsible for this decrease, which can form from the electrolyte contained in the battery by deposition on the electrodes (SEI (solid electrolyte interface)). Through such cover layers, the internal resistance of the battery increases, whereby the capacity decreases.
• DE 10 2006 025 471 A1 proposes to counteract this layer formation by adding silicon compounds to the electrolyte. It is also proposed to additionally use acyclic monocarboxylic ester compounds such as methyl formate, ethyl acetate, ethyl acetate, propyl ester, sec-butyl ester, butyl ester, methyl propionate and ethyl ester for stabilization.
• acyclic monocarboxylic ester compounds such as methyl formate, ethyl acetate, ethyl acetate, propyl ester, sec-butyl ester, butyl ester, methyl propionate and ethyl ester for stabilization.
• DE 10 2006 055 770 A1 proposes to increase the stability by an electrolyte containing lithium bis (oxalato) borate dissolved in a suitable solvent. It is an object of the present invention to reduce the capacity loss of a rechargeable lithium ion battery in cyclic charging and discharging operation, not resorting to the compounds mentioned above in the prior art. The object is achieved in that one or more esterified aliphatic dicarboxylic acids is added to the electrolyte of the battery in the loading and unloading operation to reduce the capacity loss of a rechargeable lithium-ion battery.
• the subject matter of the present invention is thus a method for reducing the electrical capacity loss of a rechargeable lithium ion battery during charging and discharging operation comprising step (i):
• lithium ion battery includes terms such as “lithium ion secondary battery”, “lithium battery”, “lithium ion secondary battery”, and “lithium ion cell”. This means that the term “lithium-ion battery” is used as a generic term for the terms used in the prior art.
• the introduction of the aliphatic dicarboxylic acid ester into the electrolyte reduces the electrical capacity loss occurring in the charge and discharge cycle.
• the electrical capacity loss is particularly pronounced during the first charge / discharge cycles, since it comes here to the formation of the mentioned outer layers on the electrodes.
• the method according to the invention is characterized in that the capacity loss after the first loading and unloading and the second loading and unloading is reduced.
• the capacity loss of the battery which is irreversible, can then be determined by determining the capacity of the battery after the first charging and after the first discharging or the second charging and the second discharging. Suitable methods are known to the person skilled in the art. In one embodiment of the method, the capacity loss may be expressed as a percentage capacity loss (Q - Q 2 ) * 100% / Qi, where Q is the capacity after the first charge and discharge and Q 2 is the capacity after the second charge. For each additional cycle, the corresponding capacity loss can be determined analogously.
• the esterified dicarboxylic acid is selected so that when the esterified dicarboxylic acid is added to the electrolyte and the battery is started up, the capacity loss is lower than the capacity loss of the battery if its electrolyte does not contain esterified dicarboxylic acid and the battery is put into operation.
• the esterified dicarboxylic acid is selected such that the irreversible capacity loss is at most 90% of the irreversible capacity loss of the battery when put into service in the absence of the esterified dicarboxylic acid, preferably at most 90%, more preferably at most 85%.
• the capacity loss is generally proportional to the increase of the internal resistance of the battery, the capacity loss can also be expressed indirectly by determining the increase of the internal resistance. It is also possible to express the capacity loss via the voltage applied to the battery in the charging and discharging operation or the removable current.
• the term "method of reducing electrical capacity loss” is synonymous with the terms “method of reducing the increase in electrical capacity loss” Internal Resistance “or” Voltage Reduction Reduction Procedure “or” Power Loss Reduction Procedure ".
• the capacity loss can thus be determined in one embodiment, the voltage loss of the battery.
• the capacitance loss is expressed as the voltage loss (L ⁇ -U 2 ) * 100% / U 1 , where U-, the voltage after the first charge and discharge and U 2 is the voltage after the second charge.
• the voltage loss can be determined accordingly for each further cycle.
• the esterified aliphatic dicarboxylic acid is selected such that the voltage loss is expressed as (Ui-U 2 ) * 100% / Ui, where Ui is the voltage after the first charge and discharge and U 2 is the voltage after the second charge is less than 10%.
• the esterified aliphatic dicarboxylic acid is selected such that the stress loss expressed as (L ⁇ -U 2 ) * 100% / where L is the voltage after the first charge and discharge and U 2 is the voltage after the second charge is less than 5%.
• the esterified aliphatic dicarboxylic acid is selected such that the voltage loss is expressed as (Ui-U 2 ) * 100% / L, where Ui is the voltage after the first charge and discharge and U 2 the voltage after the second Loading is less than 1%.
• the electrical capacity loss can be counteracted in particular by adding esterified aliphatic dicarboxylic acids of the formula RrOOC- (CH 2) x -COO-R 2 to the electrolyte of a lithium-ion battery, where x is a is an even number between 0 and 12 and Ri and R 2 are independently an unbranched or branched alkyl radical having 1 to 8 carbon atoms.
• esters used for the invention are either commercially available and / or can be prepared by conventional methods known to those skilled in the art, for example by esterification of the dicarboxylic acids with the corresponding alcohols.
• Ri and R 2 are identical.
• esters have different esterification components, ie Ri and R 2 are different.
• esters are esters of dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, azelaic acid, suberonic acid, sebacic acid.
• dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, azelaic acid, suberonic acid, sebacic acid.
• esters of adipic acid are used as dicarboxylic esters.
• Adipic acid esters known from the prior art can be used, ie dimethyl, diethyl, dipropyl, dibutyl, dipentyl, dihexyl adipate. While these compounds are used in the art as plasticizers, they are used for the present invention for reducing the electrical capacity loss of a rechargeable lithium ion battery in charging and discharging operation.
• DE 699 04 932 T2 discloses plasticizers for the production of separators or electrodes used in electrochemical cells. These plasticizers are used to form porous polymer structures. Dimethyl, diethyl, dipropyl, dibutyl, dioctyl adipate are disclosed as suitable plasticizers. Dimethyl succinate, dimethyl suberate and sebacate are also suitable. The plasticizers are removed prior to activation of the electrochemical cell, for example by extraction.
• DE 699 1 1 751 T2 discloses a rechargeable battery structure in the form of a laminate.
• the structure is prepared in the presence of an adipic acid ester having as alcohol component an alcohol of up to six carbon atoms.
• an adipic acid ester having as alcohol component an alcohol of up to six carbon atoms.
• dimethyl, diethyl, dipropyl, dibutyl, dipentyl, Dihexyladipat be used, which are used in the manufacturing process of the structure as a plasticizer.
• the document discloses that the dimethyl adipate (DMA) used in the examples can be removed from the battery structure as well as in the electrolyte of the battery in an amount of 5 to 20% by weight.
• DMA dimethyl adipate
• the initial loss of the battery structure containing DMA after the first cycle is larger than that in the structure without DMA.
• DE 751 as a whole teaches to remove the plasticizers (esters) prior to activation of the cell.
• adipic acid esters are used in which the alcohol component contains an unbranched alkyl radical having 1 to 6 carbon atoms.
• adipic acid esters are used in which the alcohol component contains a branched alkyl radical having 3 to 6 carbon atoms.
• Particularly effective adipic acid esters are also diethyl adipate and / or dibutyl adipate.
• the process according to the invention is characterized in that the esterified aliphatic dicarboxylic acid is diethyl adipate and / or dibutyl adipate.
• x 0 and the esterified aliphatic dicarboxylic acid is selected from dimethyloxalate, diethyl oxalate, dipropyloxalate, dibutyl oxalate, diphenyl oxalate, dihexyl oxalate.
• the esterified aliphatic dicarboxylic acid can be introduced in relatively large amounts in the electrolyte. It is generally effective even when incorporated in amounts up to 20% by weight, based on the total weight of organic solvent and esterified aliphatic dicarboxylic acid.
• the esterified aliphatic dicarboxylic acid is incorporated in the electrolyte in an amount of from 0.1% to 20% by weight, based on the total weight of organic solvent and esterified aliphatic dicarboxylic acid.
• the esterified aliphatic dicarboxylic acid is incorporated in an amount of 0.5 to 5% by weight, more preferably 1 to 4% by weight.
• the introduction of the esterified aliphatic dicarboxylic acid can be carried out by adding in the form of pouring into the electrolyte. It has been found that a very good activity can be achieved even at relatively low levels, ie in amounts of less than 5% by weight or even up to 4% by weight.
• the esterified aliphatic dicarboxylic acid is incorporated in the electrolyte in an amount of 0.5 to 5 weight percent, based on the total weight of organic solvent and esterified aliphatic dicarboxylic acid.
• esterified aliphatic dicarboxylic acid is incorporated in the electrolyte in an amount of 1 to 4% by weight, based on the total weight of organic solvent and esterified aliphatic dicarboxylic acid.
• the electrolyte used in the lithium-ion battery is nonaqueous. It comprises at least one organic solvent and one conducting salt.
• the electrolyte for lithium-ion batteries comprises an organic solvent and a conductive salt dissolved therein, preferably based on lithium.
• Preferred lithium salts have inert anions and are non-toxic.
• Suitable lithium salts are preferably lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium bis (trifluoromethylsulfonyl imide), lithium trifluoromethanesulfonate, lithium tris (trifluoromethylsulfonyl) methide, lithium tetrafluoroborate, lithium perchlorate, lithium tetrachloroaluminate, lithium chloride, lithium (bisoxalato) borate, and mixtures thereof.
• the lithium salt is selected from LiPF 6, LiBF 4, LiCI0 4, LiAsF 6, LiCF 3 S0 3, LiN (CF 3 S0 2) 2, LiC (CF 3 S0 2) 3, LiS0 3 C x F 2x + 1 , LiN (S0 2 C x F 2 x + i) 2 or LiC (S0 2 C x F 2x + i) 3 with 0 ⁇ x ⁇ 8, Li [(C 2 O 4 ) 2 B], and mixtures of two or more of these salts.
• the electrolyte is present as an electrolyte solution. Suitable solvents are preferably inert.
• Suitable solvents include, for example, ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, methylpropycarbonate, butylmethyl carbonate, ethylpropyl carbonate, dipropyl carbonate, cyclopentanones, sulfolanes, dimethylsulfoxide, 3-methyl-1,3-oxazolidine-2-one, ⁇ -butyrolactone, 1, 2-diethoxymethane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, methyl acetate, ethyl acetate, nitromethane, 1,3-propanesultone, and mixtures of two or more of these solvents.
• the conductive salt is LiPF 6 .
• the organic solvent is selected from ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, butyl methyl carbonate, ethyl propyl carbonate, dipropyl carbonate, or a mixture of two or more thereof.
• the electrolyte may include other adjuvants commonly used in electrolytes for lithium ion batteries.
• these are free-radical scavengers such as biphenyl, flame retardant additives such as organic phosphoric acid esters or hexamethylphosphoramide, or acid scavengers such as amines.
• So-called Kochladeadditive such as cyclohexylbenzene may also be included in the electrolyte.
• Adjuvants which can influence the formation of the "solid electrolyte interface” layer (SEI) on the electrodes, preferably carbon-containing electrodes, can also be used in the electrolyte.
• SEI solid electrolyte interface layer
• Another embodiment is also characterized in that the electrolyte contains at least one of the esterified aliphatic dicarboxylic acids and vinylene carbonate but no propanesultone.
• a further subject of the invention is a nonaqueous electrolyte for a rechargeable lithium ion battery, characterized in that said electrolyte comprises:
• esterified aliphatic dicarboxylic acid preferably an esterified aliphatic dicarboxylic acid of the formula Ri-OOC- (CH 2) x -COO-Px 2 , where x is an even number between 0 and 12 and Ri and R 2 are independently an unbranched or branched alkyl radical 1 to 8 carbon atoms;
• esterified aliphatic dicarboxylic acid in an amount of 0.5 to 4 wt.% Is contained in the electrolyte, preferably from 1 to 2.5 wt .-% based on the total weight of organic solvent and esterified aliphatic dicarboxylic acid.
• the electrolyte has the said composition, in particular during the charging and / or discharging operation of the lithium-ion battery.
• a further subject of the invention is also an electrolyte for a rechargeable lithium ion battery, characterized in that said electrolyte comprises:
• esterified aliphatic dicarboxylic acid preferably an esterified aliphatic dicarboxylic acid of the formula of the formula R OOC- (CH 2) x -COO-R 2 , wherein x is an even number between 0 and 12 and Ri and R 2 are independently an unbranched or branched alkyl radical with 1 to 8 carbon atoms; wherein dimethyl adipate is excluded.
• diethyl adipate, dipropyl adipate, dibutyl adipate, dipentyl adipate, dihexyl adipate as added versed dicarboxylic acid are excluded in addition to dimethyl adipate.
• the nonaqueous electrolyte of the invention for a rechargeable lithium ion battery is characterized in that said electrolyte comprises: at least one organic solvent;
• Another object of the invention is also a lithium-ion battery, which comprises a positive electrode, a negative electrode, a separator and the electrolyte according to the invention.
• the present invention also relates to the use of any of the above methods or electrolytes for reducing said capacity loss.
• 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. Then the positive electrode is the cathode.
• the term “negative electrode” means the electrode that is able to emit electrons when in use. Then the negative electrode is the anode.
• the anode of the battery of the invention may be made of a variety of materials suitable for use with a lithium ion electrolyte battery.
• the negative electrode may contain lithium metal or lithium in the form of an alloy, either in the form of a foil, a grid, or in the form of particles held together by a suitable binder.
• the use of lithium metal oxides such as lithium titanium oxide is also possible.
• Suitable materials which are capable of forming lithium intercalation compounds can be used.
• Suitable materials for the negative electrode then include, for example, graphite, synthetic graphite, carbon black, mesocarbon, doped carbon, fullerenes, niobium pentoxide, tin alloys, tin dioxide, silicon, titanium dioxide, and mixtures of these substances.
• the cathode of the battery according to the invention preferably comprises a compound having the formula LiMP0 4 , wherein M is at least one transition metal cation of the first row of the Periodic Table of the Elements, this transition metal cation preferably from the group consisting of Mn, Fe, Ni and Ti or a combination of these elements is chosen, and preferably has an olivine structure, preferably parent olivine, wherein Fe is particularly preferred.
• a lithium iron phosphate with olivine structure of the empirical formula LiFePO 4 can be used.
• a lithium iron phosphate containing an element M selected from the group consisting of Mn, Cr, Co, Cu, Ni, V, Mo, Ti, Zn, Al, Ga, B and Nb can be used.
• the lithium iron phosphate contains carbon to increase the conductivity.
• the lithium iron phosphate with olivine structure used for the production of the positive electrode has the empirical formula LixFei -y M y PO 4 , wherein M represents at least one element selected from the group consisting of Mn, Cr, Co, Cu, Ni, V , Mo, Ti, Zn, Al, Ga, B and Nb, with 0.05 ⁇ x ⁇ 1, 2 and 0 ⁇ y ⁇ 0.8.
• the positive electrode preferably contains the lithium iron phosphate in the form of nanoparticles.
• the nanoparticles can take any shape, that is, they can be coarse-spherical or elongated.
• the lithium iron phosphate has a particle size measured as a Dg 5 value of less than 15 pm. Preferably, the particle size is smaller than 10 pm.
• the lithium iron phosphate has a particle size measured as D 95 value between 0.005 pm to 10 pm. In a further embodiment, the lithium iron phosphate has a particle size measured as D 95 value of less than 10 pm, wherein the D 50 value is 4 pm ⁇ 2 pm and the D 10 value is less than 1, 5 pm.
• the values given can be determined by measurement using static laser light scattering (laser diffraction, laser diffractometry). The methods are known from the prior art.
• the cathode may also be a lithium manganate, preferably spinel-type LiMn 2 O, a lithium cobaltate, preferably LiCoO 2 , or a lithium nickelate, preferably LiNiO 2 , or a mixture of two or three of these oxides, or a lithium mixed oxide comprising nickel, manganese and cobalt (NMC).
• a lithium manganate preferably spinel-type LiMn 2 O
• a lithium cobaltate preferably LiCoO 2
• a lithium nickelate preferably LiNiO 2
• a mixture of two or three of these oxides or a lithium mixed oxide comprising nickel, manganese and cobalt (NMC).
• NMC nickel, manganese and cobalt
• the cathode comprises at least one active material of a lithium-nickel-manganese-cobalt mixed oxide (NMC), which is not present in a spinel structure, in a mixture with a lithium manganese oxide (LMO) in spinel structure.
• NMC lithium-nickel-manganese-cobalt mixed oxide
• LMO lithium manganese oxide
• the active material comprises at least 30 mol%, preferably at least 50 mol% NMC and at least 10 mol%, preferably at least 30 mol% LMO, in each case based on the total moles of the active material of the cathodic electrode (ie not based on the cathodic Total electrode, which in addition to the active material may also comprise conductivity additives, binders, stabilizers, etc.).
• NMC and LMO together account for at least 60 mole% of the active material, more preferably at least 70 mole%, more preferably at least 80 mole%, even more preferably at least 90 mole%, each based on the total moles of active material of the cathodic electrode (ie not based on the cathodic electrode as a whole, which in addition to the active material can still comprise conductivity additives, binders, stabilizers, etc.).
• the composition of the lithium-nickel-manganese-cobalt mixed oxide there are no restrictions with respect to the composition of the lithium-nickel-manganese-cobalt mixed oxide, except that this oxide in addition to lithium at least 5 mol%, preferably in each case at least 15 mol%, more preferably in each case at least 30 mol% of nickel, manganese and cobalt must contain, in each case based on the total number of moles of transition metals in lithium-nickel-manganese-cobalt mixed oxide.
• the lithium-nickel-manganese-cobalt mixed oxide can be doped with any other metals, in particular transition metals, as long as it is ensured that the abovementioned molar minimum amounts of Ni, Mn and Co are present.
• a lithium-nickel-manganese-cobalt mixed oxide of the following stoichiometry is particularly preferred: wherein the proportion of Li, Co, Mn, Ni and O can each vary by +/- 5%.
• the lithium iron phosphate or lithium oxide (s) used and the materials used for the negative electrode (a) are generally held together by a binder holding these materials on the electrode.
• a binder holding these materials on the electrode.
• polymeric binders can be used.
• polyvinylidene fluoride polyethylene oxide, polyethylene, polypropylene, polytetrafluoroethylene, polyacrylate, ethylene (propylene-diene monomer) copolymer (EPDM), and mixtures and copolymers thereof may preferably be used.
• the separator used for the battery must be permeable to lithium ions to ensure ion transport for lithium ions between the positive and negative electrodes. On the other hand, the separator must be insulating for electrons.
• microporous films or membranes can be used.
• the films or membranes comprise polyolefins. Suitable polyolefins are preferably polyethylene, polypropylene, or laminates of polyethylene and polypropylene.
• separators are used which comprise nonwoven polymer fibers.
• the separator of the battery according to the invention comprises a nonwoven made of nonwoven polymer fibers, also known as "non-woven fabrics", which are not electrically conductive.
• nonwoven is used synonymously with terms such as “knitted fabric” or “felt”. Instead of the term “unwoven” the term “not woven” is used.
• the nonwoven is flexible and has a thickness of less than 30 pm.
• Methods for producing such nonwovens are known in the art.
• the polymer fibers are selected from the group of polymers consisting of polyacrylonitrile, polyolefin, polyester, polyimide, polyether imide, polysulfone, polyamide, polyether.
• Suitable polyolefins are, for example, polyethylene, polypropylene, polytetrafluoroethylene, polyvinylidene fluoride.
• Preferred polyesters are preferably polyethylene terephthalates.
• the separator comprises a nonwoven, which is coated on one or both sides with an inorganic material.
• 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 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 ion-conductive inorganic material is preferably ion-conducting in a temperature range of -40 ° C to 200 ° C, i. ion-conducting for the lithium ions.
• the ion-conducting material comprises or consists of zirconium oxide.
• a separator which consists of an at least partially permeable carrier, which is not or only poorly electron-conducting.
• This support is coated on at least one side with an inorganic material.
• an organic material is used, which is designed as non-woven web.
• the organic material is in the form of polymer fibers, preferably polymer fibers of polyethylene terephthalate (PET).
• PET polyethylene terephthalate
• 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 comprises 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 largest diameter of less than 100 nm.
• 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.
• 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 contribute significantly to the safety or lack of security of a lithium high performance or lithium high energy battery.
• Polymer separators generally stop any current transport through the electrolyte 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 to 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.
• shut-down temperature the so-called "shut-down temperature”
• 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.
• shutdown the polymer structure of the carrier material and penetrates into the pores of the inorganic material and this thereby closing.
• breakdown break-down
• separators can be produced that can meet the requirements for separators in high-performance batteries, especially lithium high-performance batteries.
• the simultaneous use of particle particles of exactly matched oxide particles for the production of the porous (ceramic) coating results in a particularly high porosity of the finished separator, the pores still being sufficiently small to prevent undesired "lithium oxide” growth. Whiskers "through the separator to prevent.
• the separators which can be used for the battery according to the invention also have the advantage that the anions of the conducting 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 located on and in this nonwoven, the material of the nonwoven being selected from non-woven, non-electrically conductive polymer fibers, is also distinguished by the fact that the nonwoven a thickness of less than 30 microns, a porosity of more than 50%, preferably from 50 to 97% and a pore radius distribution has, wherein 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 ⁇ m, preferably a thickness of 10 to 20 ⁇ m. Also particularly 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.
• thinner separators allow increased packing density in a battery pack so that one can store a larger amount of energy in the same volume.
• the web has a porosity of 60 to 90%, more preferably from 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.
• non-electrically conductive fibers of polymers as defined above which are preferably selected from polyacrylonitrile (PAN), polyesters such.
• PAN polyacrylonitrile
• PET Polyethylene terephthalate
• PO polyolefin
• PP polypropylene
• PE polyethylene
• the polymer fibers of the nonwovens preferably have a diameter of from 0.1 to 10 ⁇ m, more preferably from 1 to 4 ⁇ m.
• 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 has a porous, electrically insulating, ceramic coating on and in the fleece.
• 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 0.5 to 7 ⁇ m, preferably 1 to 5 ⁇ m and very particularly preferably 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 ⁇ m, preferably from 1 to 5 ⁇ m and very particularly preferably from 1.5 to 3 pm, which are bonded to an oxide of the elements Zr or Si.
• 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 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 be calculated from the volume and density of the feedstock used, 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.
• the high tensile strength and the good bendability of the separator have the advantage that changes in the geometries of the electrodes occurring during the charging and discharging of a battery can be through the separator without being damaged.
• the flexibility also has the advantage that commercially standardized winding cells can be produced with this separator. In these cells, the electrode / separator layers are spirally wound together in a standardized size and contacted.
• the preparation of the lithium-ion battery according to the invention can be carried out in principle by methods known in the art.
• the active material used for example, the lithium iron phosphate, as a powder on the Electrode deposited and compacted into a thin film, optionally using a binder.
• the other electrode may be laminated on the first electrode, the separator being laminated in the form of a foil beforehand on the negative or the positive electrode. It is also possible to simultaneously process the positive electrode, the separator and the negative electrode under mutual lamination. The composite of electrodes and separator is then surrounded by a housing. Electrolyte can be filled as described in the prior art. This combination of improved properties is extremely beneficial to the use of the inventive lithium-ion battery in the charge / discharge cycle as a driving force for mobile information devices, tools, electric powered automobiles, and hybrid-powered automobiles. Examples
• a lithium ion battery with Separion® as separator contained as the electrolyte a mixture of ethylene carbonate and propylene carbonate in a ratio of 1: 1 and was 1.15 molar of LiPF 6 .
• the electrolyte contained 1, 5 wt% vinylene carbonate and 2 wt .-% biphenyl based on the total weight of the electrolyte.
• the battery was charged with high current pulses at a starting temperature of 75 ° C. and then discharged (charging: 150 A, 5 pulses (628 W), discharging: 225 A, 1 pulse (790 W), total duration of test: 1 h).

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• 2010
  • 2010-05-19 DE DE102010020992A patent/DE102010020992A1/de not_active Withdrawn
• 2011
  • 2011-05-06 US US13/813,295 patent/US20140017547A1/en not_active Abandoned
  • 2011-05-16 CN CN2011800344259A patent/CN103004004A/zh active Pending
  • 2011-05-16 EP EP11719774A patent/EP2572399A1/de not_active Withdrawn
  • 2011-05-16 WO PCT/EP2011/002418 patent/WO2011144317A1/de active Application Filing

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