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(11) EP 1 873 861 B1

(12) EUROPEAN PATENT SPECIFICATION

(45) Date of publication and mention (51) Int Cl.: of the grant of the patent: H01M 10/05 (2010.01) C01B 25/455 (2006.01) 12.06.2013 Bulletin 2013/24 C01D 15/00 (2006.01) H01M 10/0525 (2010.01) H01M 10/0568 (2010.01) H01M 10/0569 (2010.01) (21) Application number: 06731488.0 (86) International application number: (22) Date of filing: 10.04.2006 PCT/JP2006/307541

(87) International publication number: WO 2006/115025 (02.11.2006 Gazette 2006/44)

(54) METHOD FOR PRODUCING SOLUTION FOR BATTERY AND BATTERY USING SAME VERFAHREN ZUR HERSTELLUNG EINER ELEKTROLYTLÖSUNG FÜR EINE LITHIUMIONENBATTERIE UND BATTERIE DAMIT PROCEDE DE PRODUCTION D’UNE SOLUTION ELECTROLYTIQUE POUR UNE BATTERIE A LITHIUM ET BATTERIE L’UTILISANT

(84) Designated Contracting States: • SAKAGUCHI,Hiroaki DE FR GB c/oChemical Research Center 5253 Oaza Okiube,Ube-shi,Yamaguchi 755-0001 (30) Priority: 19.04.2005 JP 2005120558 (JP)

(43) Date of publication of application: (74) Representative: Manitz, Gerhart 02.01.2008 Bulletin 2008/01 Manitz, Finsterwald & Partner GbR Martin-Greif-Strasse 1 (73) Proprietor: CENTRALGLASS COMPANY,LIMITED 80336 München (DE) Ube-shi, Yamaguchi-ken 755-0001 (JP) (56) References cited: (72) Inventors: EP-A1- 1 055 640 WO-A1-99/41193 • OE, Meguru CA-A1- 2 193 119 JP-A- 9 165 210 c/oChemical Research Center JP-A- 9 245 807 JP-A- 06 056 413 5253 Oaza Okiube,Ube-shi,Yamaguchi 755-0001 JP-A- 11 171 518 JP-A- 2000 082 474 (JP) JP-A- 2000 211 907 US-A- 3 607 020 •SATO,Keiji US-B1- 6 387 340 c/oChemical Research Center 5253 Oaza Okiube,Ube-shi,Yamaguchi 755-0001 (JP)

Note: Within nine months of the publication of the mention of the grant of the European patent in the European Patent Bulletin, any person may give notice to the European Patent Office of opposition to that patent, in accordance with the Implementing Regulations. Notice of opposition shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). EP 1 873 861 B1

Printed by Jouve, 75001 PARIS (FR) 1 EP 1 873 861 B1 2

Description JP 09-245,807 A, EP 1 055 640 A and US 3,607,020. [0005] WO 99/41193 A1 relates to a method for pro- TECHNICAL FIELD ducing lithium hexafluorophosphate, wherein lithium flu- oride is reacted with phosphorous pentachloride in dieth- [0001] The present invention relates to a method for 5 ylether. producing an electrolyte solution for lithium ion batteries, [0006] US 6,387,340 B1 is related to a method for pro- which solution contains lithium hexafluorophosphate as ducing lithium hexafluorophosphate, in which phospho- the electrolyte, and to lithium ion batteries using the rous pentachloride is reacted with hydrogen to same. prepare phosphorous pentafluoride, whereafter the 10 phosphorous pentafluoride is reacted with lithium chlo- BACKGROUND OF THE INVENTION ride in . [0007] As mentioned above, each of the conventional [0002] There have been proposed various methods for methods was not necessarily satisfactory in terms of re- producing lithium hexafluorophosphate. For example, action yield, easiness of control of reaction, purity of the there is a method (Patent Publication 1) of reacting a15 obtained product, and the like. solid lithium fluoride with a gaseous phosphorus pen- tafluoride with no solvent. In this method, a film of the Patent Publication 1: Japanese Patent Publication reaction product is formed on the surface of lithium fluo- 64-72901 ride, thereby the reaction does not proceed completely, Patent Publication 2: Japanese Patent Application and the unreacted lithium fluoride remains. Furthermore, 20 Publication 10-72207 there are a method (Patent Publication 2) of reacting lith- Patent Publication 3: Japanese Patent Application ium fluoride with HF in , a Publication 10-81505 method (Patent Publication 3) of reacting phosphorus Patent Publication 4: Japanese Patent Application trichloride, elemental chloride and HF, and the like. In Publication 9-165210 each of these,phosphorus trichloride or phosphorus pen- 25 Non-patent Publication 1: J. Chem. Soc. Part 4, 4408 tachloride, which is highly hygroscopic, is reacted directly (1963) with HF. Therefore, moisture contained in these and moisture absorbed from the air upon charging are intro- SUMMARY OF THE INVENTION duced, and a lithium oxyfluoride, such as LiPO4, which is easily hydrolyzed, is generated in and mixed with the 30 [0008] It is an object of the present invention to directly product. Even if one tries to use it as the electrolyte of a produce an electrolyte solution in an organic solvent, up- lithium ion battery, it is hydrolyzed by a trace amount of on producing an electrolyte solution containing lithium moisture in the electrolyte solution to generate an acidic hexafluorophosphate as the electrolyte. substance. Since the electrolyte solution is damaged [0009] As a result of an eager examination in view of thereby, there is a problem that it cannot be used as the 35 the above-mentioned prior art problems, the present in- electrolyte of a lithium ion battery. Furthermore, there is ventors have found that an electrolyte solution for lithium a method (Patent Publication 4) of reacting lithium fluo- ion batteries can easily be produced by reacting a lithium ride with in an organic solvent. halide, phosphorus pentachloride, and hydrogen fluoride However, since phosphorus pentafluoride is a gas, a cyl- in an organic solvent, thereby reaching the present in- inder is necessary for its handling. Therefore, the pro- 40 vention. duction of phosphorus pentafluoride is complicated. [0010] The present invention relates to a method for Since gas is handled, it involves danger, and an expert producing an electrolyte solution for lithium ion battery, knowledge is necessary. Furthermore, it is necessary to comprising reacting a lithium halide that is one selected purify a phosphorus pentafluoride used to have a high from the group consisting of lithium fluoride, lithium chlo- purity. Therefore, there is a problem that the cost be-45 ride, , or a mixture of at least comes high to greatly affect the price. two of these, with phosphorus pentachloride and hydro- [0003] Furthermore, there is a method (Non-patent gen fluoride in a nonaqueous organic solvent, thereby Publication 1) of reacting a gaseous phosphorus pen- producing lithium hexafluorophosphate as an electrolyte tafluoride with lithium fluoride that is dissolved when an- of the electrolyte solution. hydrous hydrogen fluoride is used as a solvent. In this 50 [0011] According to the present invention, upon pro- method, handling is difficult since anhydrous hydrogen ducing an electrolyte solution for lithium ion batteries, fluoride, which is high in vapor pressure, is used as the which solution contains lithium hexafluorophosphate as solvent. the electrolyte, there is provided a method for producing [0004] CA 2,193,119 discloses a method for producing an electrolyte solution for lithium ion batteries, which is an electrolytic solution containing a solute of lithium hex- 55 characterized in that lithium fluoride, , lith- afluorophosphate, wherein lithium fluoride is reacted with ium bromide, lithium iodide or a mixture of any of these phosphorouspentafluoride in a non-aqueous organic sol- is reacted with phosphorus pentachloride and hydrogen vent. Similar methods are known from JP 09-165,210 A, fluoride in a nonaqueous organic solvent.

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DETAILED DESCRIPTION ride, lithium bromide or lithium iodide is greater than 600g relative to the solvent, the product becomes saturation, [0012] According to the present invention, the reaction and a film is formed on the surface of lithium fluoride, yield is high, the reaction control is also easy, and the lithium chloride, lithium bromide or lithium iodide. The point of product purity is also sufficiently satisfactory, as 5 unreacted lithium fluoride, lithium chloride, lithium bro- compared with the conventional methods for producing mide, lithium iodide or mixture of these remains, and vis- anelectrolyte solution containing lithium hexafluorophos- cosity of the solution increases. Therefore, a separation phate. Furthermore, since a solvent for lithium batteries operation such as filtration becomes difficult. is used as the solvent, it is possible to use the solution [0018] Although the amount of hydrogen fluoride is not after the reaction directly as an electrolyte solution. Thus, 10 limited, it is 450g or less, preferably 350g or less, relative it is possible to provide a very simplified production meth- to 1 liter of the solvent. od. [0019] The amounts of the lower limits of introducing [0013] In the production method of the present inven- the raw materials such as these lithium fluoride, lithium tion, the reaction yield is high, the reaction control is also chloride, phosphorus pentachloride, and hydrogen fluo- easy, and the point of product purity is also sufficiently 15 ride are each 1g relative to 1 liter of the solvent. If they satisfactory. Furthermore, since one for lithium batteries are less than 1g relative to the solvent, the battery elec- is used as the solvent, it is possible to use the solution trolyte concentration becomes low, and it does not exhibit after the reaction directly as an electrolyte solution. a performance that is satisfactory as an electrolyte solu- [0014] The production method of the present invention tion for lithium ion batteries. If the electrolyte concentra- is conducted in one kind or a mixed solvent of several 20 tion is increased by concentration, the solvent for batter- kinds of the above-mentioned nonaqueous organic sol- ies is wasted, and the cost becomes excessive. vents for lithium ion batteries. Although lithium fluoride, [0020] In this reaction, lithium hexafluorophosphate as lithium chloride, lithium bromide or lithium iodide, and the product is hydrolyzed by moisture. Therefore, it is phosphorus pentachloride, and hydrogen fluoride, which necessary to conduct the reaction in an atmosphere con- are the raw materials, are introduced into these solvents, 25 taining no moisture. That is, it is preferable to conduct the order of introduction is not particularly limited. Rela- the reaction in vacuum or in an inert gas atmosphere tive to a nonaqueous organic solvent for batteries, lithium such as nitrogen. fluoride, lithium chloride, lithium bromide, lithium iodide [0021] A solvent for lithium ion batteries is used as the or a mixture of any of these is mixed with phosphorus solvent in the solution obtained as above. Therefore, it pentachloride, which are raw materials. Since these are 30 is possible to use the solution obtained by the reaction low in , hydrogen fluoride is introduced to con- directly as an electrolyte solution for lithium ion batteries. duct the reaction under a condition that they are dis- It is possible to obtain lithium hexafluorophosphate of persed in the solvent. Since lithium hexafluorophosphate high purity by conducting a precipitation separation by formed herein has a very high solubility, it is dissolved in an operation such as cooling or concentration. the solvent and does not remain as a film on the surface 35 [0022] In the following, the present invention is de- of the raw materials. Therefore, the reaction proceeds scribed in detail by examples. The present invention is, completely. however, not limited by the examples. [0015] A carbonate compound or ether compound, which is high in chemical stability and in which solubility EXAMPLE 1 of lithium hexafluorophosphate is high, is preferable as 40 the nonaqueous organic solvent used. For example, [0023] In a reactor made of PTFE, 5.0g of lithium flu- there are ethylene carbonate, dimethyl carbonate, diethyl orideand 20.0g ofphosphorus pentachloridewere added carbonate, ethyl methyl carbonate, 1,2-dimethox- to 100ml of dimethyl carbonate, thereby conducting mix- yethane, and the like. ing and dispersion. While this dispersion liquid was [0016] The temperature range upon conducting this re- 45 cooled and maintained at 10°C, hydrogen fluoride gas action is -40°C to 100°C, preferably 0°C to 60°C. If the was bubbled through a gas introducing tube. When the reaction temperature is lower than -40°C, the solvent so- lithium fluoride dispersed in dimethyl carbonate disap- lidifies. Therefore, the reaction does not proceed. In case peared, the reaction was terminated. Upon this, the that it exceeds 100°C, scattering of the solvent or the amount of hydrogen fluoride consumed was 15.0g. reaction of the solvent with phosphorus pentachloride 50 It was possible to confirm the formation of lithium hex- occurs. This becomes a cause of coloring or viscosity afluorophosphate by19F-NMR measurement and ion increase. Therefore, it is not preferable. chromatogram of the obtained solution. It was obtained [0017] The amount of lithium fluoride, lithium chloride, with a yield of 98.7%. lithium bromide, lithium iodide or a mixture of any of these is 600g or less in total, preferably 400g or less, relative 55 EXAMPLE 2 to 1 liter of the solvent. Phosphorus pentachloride is in 1000g or less, preferably 600g or less, relative thereto. [0024] In a reaction vessel made of PTFE, 81.0g of In case that the amount of lithium fluoride, lithium chlo- phosphorus pentachloride and 17.7g of lithium chloride

3 5 EP 1 873 861 B1 6 were added to 200ml of diethyl carbonate, thereby con- was 10ppm as a result of conducting a purification of the ducting mixing and dispersion. While this dispersion liq- synthesized solution. It becomes 70ppm when converted uid was cooled and maintained at 10°C, hydrogen fluo- to the lithium hexafluorophosphate base. As a result of ride gas was bubbled through a gas introducing tube. measuring ionic conductivity of this solution, it was 7.8 When the lithium fluoride dispersed in diethyl carbonate 5 mS/cm. It was equivalent to that of one in which lithium disappeared, the reaction was terminated. Upon this, the hexafluorophosphate had been dissolved in a mixed sol- amount of hydrogen fluoride consumed was 49.2g. vent of ethylene carbonate and diethyl carbonate. [0025] The formation of lithium hexafluorophosphate [0033] Then, a test cell was prepared by using this so- was confirmed by 19F-NMR measurement and ion chro- lution, and it was subjected to a performance evaluation matogram of the obtained solution. The yield was 98.8%. 10 as an electrolyte solution by a charge and discharge test. Specifically, 5 parts by weight of polyvinylidene fluoride EXAMPLE 3 (PVDF) as a binder were mixed with 95 parts by weight of a natural graphite powder. Furthermore, N,N-dimeth- [0026] In a reaction vessel made of PTFE, 2.5g of lith- ylformamide was added to make a slurry. This slurry was ium fluoride, 4.3g of lithium chloride and 40.3g of phos- 15 applied on a nickel mesh, followed by drying at 150°C phorus pentachloride were added to a solvent obtained for 12hr, thereby making a test anode body. 10 parts by by mixing 100ml of ethylene carbonate with 100ml of di- weight of a black smoke powder and 5 parts by weight ethyl carbonate, thereby conducting mixing and disper- of PVDF were mixed with 85 parts by weight of lithium sion. While this dispersion liquid was cooled and main- cobaltate, and N,N-dimethylformamide was added to tained at 10°C, hydrogen fluoride gas was bubbled20 make a slurry. This slurry was applied on an aluminum through a gas introducing tube. When the lithium fluoride foil, followed by drying at 150°C for 12hr, thereby making and the lithium chloride dispersed in the mixed solvent a test cathode body. A test cell was constructed by using disappeared, the reaction was terminated. Upon this, the a polypropylene nonwoven fabric as the separator, the amount of hydrogen fluoride consumed was 24.1g. reaction solution of the present example as the electro- [0027] The formation of lithium hexafluorophosphate 25 lyte solution, and the above anode body and cathode was confirmed by 19F-NMR measurement and ion chro- body. Then, a constant current, charge and discharge matogram of the obtained solution. The yield was 98.8%. test was conducted under the following conditions. Both of charge and discharge were conducted at a current EXAMPLE 4 density of 0.35 mA/cm 2. The charge was conducted until 30 4.2V, and the discharge was conducted until 2.5V. This [0028] In a reaction vessel made of PTFE, 100ml of charge and discharge cycle was repeated, and the diethyl carbonate solvent were cooled and maintained at change of discharge capacity was observed. As a result, 10°C, and 20.5g of phosphorus pentachloride and 10.3g the charge and discharge efficiency was almost 100%. of hydrogen fluoride were added by bubbling through in- As a result of repeating the charge and discharge by 100 troducing tubes to conduct mixing and the reaction. Fur- 35 cycles, discharge capacity did not change at all. thermore, while the solution was maintained at 10°C, 2.6g of lithium fluoride were added to further conduct the reaction. Claims [0029] It was possible to confirm the formation of lith- ium hexafluorophosphate by19F-NMR measurement 40 1. A method for producing an electrolyte solution for and ion chromatogram of the obtained solution. The yield lithium ion battery, comprising reacting a lithium hal- was 98.7%. ide that is one selected from the group consisting of lithium fluoride, lithium chloride, lithium bromide, lith- EXAMPLE 5 ium iodide or a mixture of at least two of these, with 45 phosphorus pentachloride and hydrogen fluoride in [0030] In a reaction vessel made of PTFE, 100ml of a nonaqueous organic solvent, thereby producing ethyl methyl carbonate solvent were cooled and main- lithium hexafluorophosphate as an electrolyte of the tained at 10°C, and 83.2g of phosphorus pentachloride electrolyte solution. and 45.0g of hydrogen fluoride were added by bubbling throughintroducing tubes toconduct mixingand reaction. 50 2. A method for producing an electrolyte solution for Furthermore, while the solution was maintained at 10°C, lithium ion battery according to claim 1, wherein the a mixture of 5.2g of lithium fluoride and 8.8g of lithium nonaqueous organic solvent according to claim 1 is chloride was added to further conduct the reaction. a cyclic or chain carbonate or an ether compound [0031] It was possible to confirm the formation of lith- having at least two oxygen atoms. ium hexafluorophosphate by19F-NMR measurement 55 and ion chromatogram of the obtained solution. The yield 3. A method for producing an electrolyte solution for was 98.8%. lithium ion battery according to claim 2, wherein the [0032] The acidic impurity concentration in the solvent carbonate according to claim 2 is one selected from

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the group consisting of ethylene carbonate, propyl- le bromure de lithium, l’iodure de lithium et un mé- ene carbonate, dimethyl carbonate, diethyl carbon- lange d’au moins deux de ces halogénures de li- ate, and ethyl methyl carbonate. thium, avec du pentachlorure de phosphore et du fluorure d’hydrogène dans un solvant organique non 4. A method for producing an electrolyte solution for 5 aqueux,en produisantainsi del’hexafluorophospha- lithium ion battery according to claim 2, wherein the te de lithium comme électrolyte de la solution d’élec- ether compound according to claim 2 is 1,2- dimeth- trolyte. oxyethane. 2. Procédé pour la production d’une solution d’électro- 5. A lithium ion battery comprising an electrolyte solu- 10 lyte pour une batterie à ions lithium suivant la reven- tion obtained by the production method according to dication 1, dans lequel le solvant organique non any one of claims 1-4. aqueux suivant la revendication 1 est un carbonate cyclique ou à chaîne ou un composé du type éther comprenant au moins deux atomes d’oxygène. Patentansprüche 15 3. Procédé pour la production d’une solution d’électro- 1. Verfahren zum Herstellen einer Elektrolytlösung für lyte pour une batterie à ions lithium suivant la reven- eine Lithiumionenbatterie umfassend das Reagie- dication 2, dans lequel le carbonate suivant la reven- ren eines Lithiumhalogenids, welches eines ausge- dication 2 est un carbonate choisi dans le groupe wählt aus der Gruppe bestehend aus Lithiumfluorid, 20 consistant en le carbonate d’éthylène, le carbonate Lithiumchlorid, Lithiumbromid, Lithiumiodid oder ei- de propylène, le carbonate de diméthyle, le carbo- ner Mischung von wenigstens zwei von diesen ist, nate de diéthyle et le carbonate d’éthylméthyle. mit Phosphorpentachlorid und Fluorwasserstoff in einem nicht wässrigen organischen Lösungsmittel, 4. Procédé pour la production d’une solution d’électro- um dadurch Lithiumhexafluorophosphat als einen 25 lyte pour une batterie à ions lithium suivant la reven- Elektrolyten einer Elektrolytlösung herzustellen. dication 2, dans lequel le composé du type éther suivant la revendication 2 est le 1,2- diméthoxyétha- 2. Verfahren zum Herstellen einer Elektrolytlosung für ne. eine Lithiumionenbatterie nach Anspruch 1, wobei das nicht wässrige organische Lösungsmittel nach 30 5. Batterie à ions lithium comprenant une solution Anspruch 1 ein cyclisches oder kettiges Carbonat d’électrolyte obtenue par le procédé de production oder eine Etherverbindung mit wenigstens zwei Sau- suivant l’une quelconque des revendications 1 à 4. erstoffatomen ist.

3. Verfahren zum Herstellen einer Elektrolytlösung für 35 eine Lithiumionenbatterie nach Anspruch 2, wobei das Carbonat nach Anspruch 2 eines ist, das aus der Gruppe ausgewählt ist, welche aus Ethylencar- bonat, Propylencarbonat, Dimethylcarbonat, Diethylcarbonat und Ethylmethylcarbonat besteht. 40

4. Verfahren zum Herstellen einer Elektrolytlösung für eine Lithiumionenbatterie nach Anspruch 2, wobei die Etherverbindung nach Anspruch 2 1,2-Dime- thoxyethan ist. 45

5. Lithiumionenbatterie, welche eine Elektrolytlösung enthält, die durch ein Herstellungsverfahren nach ei- nem der Ansprüche 1 bis 4 erhalten worden ist. 50

Revendications

1. Procédé pour la production d’une solution d’électro- lyte pour une batterie à ions lithium, comprenant la 55 réaction d’un halogénure de lithium qui est un halogénure de lithium choisi dans le groupe consis- tant en le fluorure de lithium, le chlorure de lithium,

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REFERENCES CITED IN THE DESCRIPTION

This list of references cited by the applicant is for the reader’s convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

Patent documents cited in the description

• CA 2193119 [0004] • WO 9941193 A1 [0005] • JP 9165210 A [0004] [0007] • US 6387340 B1 [0006] • JP 9245807 A [0004] • JP 6472901 B [0007] • EP 1055640 A [0004] • JP 10072207 A [0007] • US 3607020 A [0004] • JP 10081505 A [0007]

Non-patent literature cited in the description

• J. Chem. Soc. Part 4, 1963, 4408 [0007]

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