WO2013094465A1 - Lithium secondary battery - Google Patents
Lithium secondary battery Download PDFInfo
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- WO2013094465A1 WO2013094465A1 PCT/JP2012/082012 JP2012082012W WO2013094465A1 WO 2013094465 A1 WO2013094465 A1 WO 2013094465A1 JP 2012082012 W JP2012082012 W JP 2012082012W WO 2013094465 A1 WO2013094465 A1 WO 2013094465A1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/362—Composites
- H01M4/364—Composites as mixtures
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- 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
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
- H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
- H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
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- 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 present invention relates to a lithium secondary battery that can be used stably even if it is continuously charged at a high voltage of 4.3 V or higher.
- lithium-containing composite oxides such as LiCoO 2 and LiMnO 2 are usually used as the positive electrode active material, and in addition to the graphitic carbon material, lithium secondary secondary materials such as LiCoO 2 and LiMnO 2 are used.
- SiO x having a structure in which ultrafine particles of Si are dispersed in SiO 2 (for example, Patent Documents 1 to 3).
- the upper limit of the charging voltage is generally set to about 4.2 V.
- Patent Document 4 discloses a lithium secondary battery in which a compound having two or more nitrile groups in a molecule is contained in a non-aqueous electrolyte to improve charge / discharge cycle characteristics and the like.
- the device may be continuously charged during actual use, such as being left for a long time while being charged, or using the device while being charged.
- This invention is made
- the lithium secondary battery of the present invention that has achieved the above-mentioned object includes a positive electrode having a positive electrode mixture layer containing a positive electrode active material on one side or both sides of a current collector, and a negative electrode active material on one side or both sides of the current collector.
- a lithium secondary battery comprising a negative electrode having a negative electrode mixture layer, a non-aqueous electrolyte, and a separator, wherein the positive electrode mixture layer of the positive electrode has a general composition formula Li 1 + y Ni 1-abc Co a Mn b M 1 c O 2 [wherein M 1 is selected from the group consisting of Mg, Al, Ti, Fe, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Sn, Sr, W, B, P, and Bi.
- the negative electrode mixture layer of the negative electrode is a material containing Si and O as constituent elements (provided that the atomic ratio x of O to Si is 0.5 ⁇ x ⁇ 1.5) )
- the non-aqueous electrolyte contains a compound having a nitrile group in the molecule.
- the present invention it is possible to provide a lithium secondary battery that can be used stably even if it is continuously charged at a high voltage of 4.3 V or higher.
- Suppressing the elution of ions of transition metal elements from the active material into the non-aqueous electrolyte is performed by using a lithium-containing composite oxide having a composition in which the elution of ions is difficult to occur as the positive electrode active material, and the non-aqueous electrolyte. This is achieved by including a component having an action of suppressing ion elution. Therefore, the lithium secondary battery of the present invention has a high capacity and can be used stably even by a method in which charging is continued continuously.
- non-aqueous electrolyte examples include a solution (non-aqueous electrolyte) in which a lithium salt is dissolved in an organic solvent.
- the non-aqueous electrolyte includes a nitrile group in the molecule. The thing containing the compound which has is used.
- the compound having a nitrile group in the molecule is adsorbed on the surface of the positive electrode to form a film in the lithium secondary battery, and the non-ion of transition metal element ions from the positive electrode active material in a charged state at a high voltage. It has a function to suppress elution into the water electrolyte. Therefore, the lithium secondary battery of the present invention functions synergistically by the above-described action of the compound having a nitrile group in the molecule and the action of the use of a positive electrode active material in which elution of transition metal element ions described later hardly occurs. Therefore, it can be used stably even if the high voltage is continuously charged.
- the compound having a nitrile group in the molecule can suppress direct contact between the positive electrode and the non-aqueous electrolyte by forming a film on the surface of the positive electrode, the non-aqueous electrolyte component accompanying charge / discharge of the battery Decomposition on the positive electrode surface and gas generation due to this can be suppressed. Therefore, in the lithium secondary battery of the present invention, the charge / discharge cycle characteristics are good, and since the battery swelling during storage can be suppressed, the storage characteristics are also good.
- Examples of the compound having a nitrile group in the molecule include a mononitrile compound having one nitrile group in the molecule, a dinitrile compound having two nitrile groups in the molecule, and a trinitrile compound having three nitrile groups in the molecule. Is mentioned. Among these, the above-mentioned actions (the action of suppressing the elution of ions of transition metal elements from the positive electrode active material by the formation of a film on the surface of the positive electrode, and the action of suppressing the reaction between the positive electrode and the nonaqueous electrolyte component) are better.
- Dinitrile compounds that is, compounds having two nitrile groups in the molecule
- R in the general formula is more preferably a linear or branched alkylene chain having 1 to 10 carbon atoms.
- the mononitrile compound examples include lauryl nitrile.
- Specific examples of the dinitrile compound represented by the above general formula include, for example, malononitrile, succinonitrile, glutaronitrile, adiponitrile, 1,4-dicyanoheptane, 1,5-dicyanopentane, 1,6-dicyano.
- the content of the compound having a nitrile group in the molecule in the non-aqueous electrolyte used in the battery is preferably 0.1% by mass or more from the viewpoint of more effectively exerting the effect of the use of these compounds. More preferably, it is 2% by mass or more. However, if the amount of the compound having a nitrile group in the molecule is too large, for example, although the storage characteristics of the battery are further improved, the effect of improving the charge / discharge cycle characteristics may be reduced. Therefore, the content of the compound having a nitrile group in the molecule in the non-aqueous electrolyte used for the battery is preferably 5.0% by mass or less, and more preferably 4.0% by mass or less.
- non-aqueous electrolyte containing a phosphonoacetate compound represented by the following general formula (1).
- R 1 , R 2 and R 3 are each independently an alkyl group having 1 to 12 carbon atoms which may be substituted with a halogen atom, and n is an integer of 0 to 6 It is.
- SiO x is used as a negative electrode active material, but in such a battery, highly active Si is exposed by grinding of SiO x particles caused by the volume change accompanying charge / discharge. (Details of the structure of SiO x will be described later), and this decomposes the nonaqueous electrolyte, so that there is a problem that the charge / discharge cycle characteristics are liable to deteriorate.
- the phosphonoacetate compound represented by the general formula (1) has a function of forming a film on the surface of the negative electrode. Even if a SiO x particle is pulverized by a volume change associated with charge and discharge, a new surface is generated. Coating well. Therefore, such a coating can highly suppress the reaction between the negative electrode active material and the nonaqueous electrolyte.
- the phosphonoacetate compound represented by the general formula (1) also has an action of suppressing swelling of the lithium secondary battery. Therefore, when the non-aqueous electrolyte containing the phosphonoacetate compound represented by the general formula (1) is used, this action and the action of the compound containing a nitrile group in the molecule are synergistic. It functions and can further improve the storage characteristics of the lithium secondary battery.
- R 1 , R 2 and R 3 are each independently a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom (for example, an alkyl group, an alkenyl group, N is an integer of 0-6. That is, R 1 , R 2 and R 3 may be different from each other, or two or more may be the same.
- a halogen atom for example, an alkyl group, an alkenyl group, N is an integer of 0-6. That is, R 1 , R 2 and R 3 may be different from each other, or two or more may be the same.
- n 0 in the general formula (1)> Trimethyl phosphonoformate, methyl diethylphosphonoformate, methyl dipropylphosphonoformate, methyl dibutylphosphonoformate, triethyl phosphonoformate, ethyl dimethylphosphonoformate, ethyl dipropylphosphonoformate, ethyl Dibutyl phosphonoformate, tripropyl phosphonoformate, propyl dimethylphosphonoformate, propyl diethylphosphonoformate, propyl dibutylphosphonoformate, tributyl phosphonoformate, butyl dimethylphosphonoformate, butyl diethylphospho Noformate, butyl dipropylphosphonoformate, methyl bis (2,2,2-trifluoroethyl) phosphonoformate, ethyl bis (2 2,2-trifluoroethyl)
- n 2 in the general formula (1)> Trimethyl 3-phosphonopropionate, methyl 3- (diethylphosphono) propionate, methyl 3- (dipropylphosphono) propionate, methyl 3- (dibutylphosphono) propionate, triethyl 3-phosphonopropionate, ethyl 3- (dimethylphosphono) propionate, ethyl 3- (dipropylphosphono) propionate, ethyl 3- (dibutylphosphono) propionate, tripropyl 3-phosphonopropionate, propyl 3- (dimethylphosphono) propionate, Propyl 3- (diethylphosphono) propionate, propyl 3- (dibutylphosphono) propionate, tributyl 3-phosphonopropionate, butyl 3- (dimethylphosphono) propionate, butyl 3- (diethylphosphono) propyl
- n 3 in the general formula (1)> Trimethyl 4-phosphonobutyrate, methyl 4- (diethylphosphono) butyrate, methyl 4- (dipropylphosphono) butyrate, methyl 4- (dibutylphosphono) butyrate, triethyl 4-phosphonobutyrate, ethyl 4- (Dimethylphosphono) butyrate, ethyl 4- (dipropylphosphono) butyrate, ethyl 4- (dibutylphosphono) butyrate, tripropyl 4-phosphonobutyrate, propyl 4- (dimethylphosphono) butyrate, propyl 4- (Diethylphosphono) butyrate, propyl dibutylphosphono) butyrate, tributyl 4-phosphonobutyrate, butyl 4- (dimethylphosphono) butyrate, butyl 4- (diethylphosphono) butyrate, butyl
- PDPA 2-propynyl diethylphosphonoacetate
- EDPA ethyl diethylphosphonoacetate
- the content of the phosphonoacetate compound represented by the general formula (1) in the non-aqueous electrolyte used for the lithium secondary battery is 0.5% by mass or more from the viewpoint of better ensuring the effect of the use. It is preferable that it is 1.0 mass% or more. However, if the content of the phosphonoacetate compound represented by the general formula (1) in the nonaqueous electrolyte is too large, the effect of improving the charge / discharge cycle characteristics of the battery may be reduced. Therefore, the content of the phosphonoacetate compound represented by the general formula (1) in the nonaqueous electrolyte used for the lithium secondary battery is preferably 30% by mass or less, and 5.0% by mass or less. More preferably.
- R 1 , R 2 , and R 3 of the general formula (1) representing the phosphonoacetate compound contains an unsaturated bond
- a carbon-carbon double bond or a carbon-carbon triplet is formed on the negative electrode surface.
- a film is formed by polymerization by opening the bond.
- the film formed in this case is highly flexible because the constituent molecule (constituent polymer) has a flexible carbon-carbon bond as the main chain.
- a non-aqueous electrolyte that also contains a halogen-substituted cyclic carbonate.
- the halogen-substituted cyclic carbonate acts on the negative electrode and has a function of suppressing the reaction between the negative electrode and the nonaqueous electrolyte component. Therefore, by using a non-aqueous electrolyte that also contains a halogen-substituted cyclic carbonate, a lithium secondary battery with better charge / discharge cycle characteristics can be obtained.
- halogen-substituted cyclic carbonate a compound represented by the following general formula (2) can be used.
- R 4 , R 5 , R 6 and R 7 represent hydrogen, a halogen element or an alkyl group having 1 to 10 carbon atoms, and a part or all of hydrogen of the alkyl group is halogen. may be substituted with an element, at least one of R 4, R 5, R 6 and R 7 are halogen, R 4, R 5, R 6 and R 7 have different respective Two or more may be the same.
- R 4 , R 5 , R 6 and R 7 are alkyl groups, the smaller the number of carbon atoms, the better.
- the halogen element fluorine is particularly preferable.
- FEC 4-fluoro-1,3-dioxolan-2-one
- the content of the halogen-substituted cyclic carbonate in the non-aqueous electrolyte used for the lithium secondary battery is preferably 0.1% by mass or more from the viewpoint of ensuring better the effect of the use, More preferably, it is at least mass%. However, if the content of the halogen-substituted cyclic carbonate in the non-aqueous electrolyte is too large, the effect of improving storage characteristics may be reduced. Therefore, the content of the halogen-substituted cyclic carbonate in the nonaqueous electrolyte used for the lithium secondary battery is preferably 10% by mass or less, and more preferably 5% by mass or less.
- a non-aqueous electrolyte that also contains vinylene carbonate (VC).
- VC acts on a negative electrode (particularly a negative electrode using a carbon material as a negative electrode active material) and has a function of suppressing a reaction between the negative electrode and a nonaqueous electrolyte component. Therefore, by using a nonaqueous electrolyte containing VC, a lithium secondary battery with better charge / discharge cycle characteristics can be obtained.
- the content of VC in the non-aqueous electrolyte used for the lithium secondary battery is preferably 0.1% by mass or more, and 1.0% by mass or more from the viewpoint of better ensuring the effect of the use. It is more preferable. However, when there is too much content of VC in a nonaqueous electrolyte, there exists a possibility that the improvement effect of a storage characteristic may become small. Therefore, the content of VC in the non-aqueous electrolyte used for the lithium secondary battery is preferably 10% by mass or less, and more preferably 4.0% by mass or less.
- the lithium salt used in the non-aqueous electrolyte is not particularly limited as long as it is dissociated in a solvent to form Li + ions and hardly causes a side reaction such as decomposition in a voltage range used as a battery.
- LiClO 4 , LiPF 6 , LiBF 4 , LiAsF 6 , LiSbF 6 and other inorganic lithium salts LiCF 3 SO 3 , LiCF 3 CO 2 , Li 2 C 2 F 4 (SO 3 ) 2 , LiN (CF 3 SO 2 ) 2 , LiC (CF 3 SO 2 ) 3 , LiC n F 2n + 1 SO 3 (n ⁇ 2), LiN (RfOSO 2 ) 2 [where Rf is a fluoroalkyl group] and the like can be used. .
- the concentration of this lithium salt in the non-aqueous electrolyte is preferably 0.5 to 1.5 mol / l, more preferably 0.9 to 1.25 mol / l.
- the organic solvent used for the non-aqueous electrolyte is not particularly limited as long as it dissolves the lithium salt and does not cause a side reaction such as decomposition in a voltage range used as a battery.
- cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, chain carbonates such as dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate; chain esters such as methyl propionate; cyclic esters such as ⁇ -butyrolactone; dimethoxyethane, Chain ethers such as diethyl ether, 1,3-dioxolane, diglyme, triglyme and tetraglyme; cyclic ethers such as dioxane, tetrahydrofuran and 2-methyltetrahydrofuran; sulfites such as ethylene glycol sulfite; May be used as a mixture of two or more.
- sulfites such as ethylene
- Non-aqueous electrolytes used in lithium secondary batteries include acid anhydrides, sulfonic acid esters, 1 for the purpose of further improving charge / discharge cycle characteristics and improving safety such as high-temperature storage and prevention of overcharge.
- acid anhydrides sulfonic acid esters 1 for the purpose of further improving charge / discharge cycle characteristics and improving safety such as high-temperature storage and prevention of overcharge.
- 3-propane sultone, diphenyl disulfide, cyclohexylbenzene, biphenyl, fluorobenzene, t-butylbenzene, and other additives (including derivatives thereof) can be added as appropriate.
- a gel obtained by adding a known gelling agent such as a polymer to the non-aqueous electrolyte (non-aqueous electrolyte) is used. You can also.
- the positive electrode according to the lithium secondary battery of the present invention one having a structure having a positive electrode mixture layer containing a positive electrode active material, a binder, a conductive additive and the like on one side or both sides of a current collector is used.
- the positive electrode active material includes a general composition formula Li 1 + y Ni 1-abc Co a Mn b M 1 c O 2 (where M 1 is Mg, Al, Ti, Fe, Cu, Zn, Ga, Ge, At least one element selected from the group consisting of Zr, Nb, Mo, Sn, W, B, P, and Bi, -0.15 ⁇ y ⁇ 0.15, 0.05 ⁇ a ⁇ 0.3 , 0.05 ⁇ b ⁇ 0.3, 0 ⁇ c ⁇ 0.03, and a + b + c ⁇ 0.5) are used.
- the lithium nickel composite oxide (a) has a high capacity, and it is difficult for metal ions to elute into the non-aqueous electrolyte in the battery, and the thermal stability is also high. Therefore, the lithium secondary battery of the present invention functions synergistically with the action of the lithium nickel composite oxide (a) and the action of the compound having a nitrile group in the molecule contained in the non-aqueous electrolyte. In addition, it can be stably used even by a method in which charging is continued continuously. Further, by using the lithium nickel composite oxide (a), the charge / discharge cycle characteristics, high-temperature storage characteristics, load characteristics, and safety of the battery can be improved.
- Ni is a component that contributes to improving the capacity of the lithium nickel composite oxide (b).
- Co contributes to an improvement in the capacity of the lithium nickel composite oxide (a) and an improvement in the packing density of the lithium nickel composite oxide (a) in the positive electrode mixture layer.
- Co suppresses fluctuations in the valence of Mn associated with Li doping and dedoping during battery charging / discharging, stabilizes the average valence of Mn at a value close to tetravalent, and further improves the reversibility of charging / discharging. It also has an enhancing effect. Therefore, from the viewpoint of satisfactorily exerting the above-described action by Co, in the general composition formula representing the lithium nickel composite oxide (a), a representing the amount of Co is 0.05 or more, 0.1 or more It is preferable that
- a representing the amount of Co is 0.3 or less, and preferably 0.2 or less.
- Mn has an effect of increasing the thermal stability of the lithium nickel composite oxide (a). Therefore, in the general composition formula representing the lithium nickel composite oxide (a), b representing the amount of Mn is 0.05 or more, and 0.1 or more from the viewpoint of satisfactorily exerting the above-described action by Mn. It is preferable that
- b representing the amount of Mn is 0.3 or less, and preferably 0.2 or less.
- the lithium nickel composite oxide (a) includes Mg, Al, Ti, Fe, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Sn, W, B, may contain at least one element M 1 is selected from the group consisting of P and Bi.
- the amount of the element M 1 in the lithium nickel composite oxide (a) is too large, Ni and Co, with the amount of Mn is low, the action of these there is a possibility that not sufficiently exhibited. Therefore, in the general composition formula representing the lithium nickel composite oxide (a), c representing the amount of the element M 1 is 0.03 or less, and preferably 0.01 or less. Further, the lithium nickel composite oxide (a) may not contain the element M 1, in the general formula, the c representing the amount of the element M 1, is greater than zero.
- the total amount “a + b + c” of a representing the amount of Co, b representing the amount of Mn, and c representing the amount of the element M 1 is If the amount is too large, the amount of Ni is decreased, and the capacity of the lithium nickel composite oxide (a) may be decreased. Therefore, the “a + b + c” is 0.5 or less, and preferably 0.3 or less.
- “1-abc” representing the amount of Ni is 0.5 or more, and preferably 0.6 or more.
- it is 0.9 or less, and preferably 0.8 or less.
- the lithium nickel composite oxide (a) has a higher true density and a higher energy volume density, particularly when the composition is close to the stoichiometric ratio. ⁇ 0.15 ⁇ y ⁇ 0.15, and by adjusting the value of y in this way, the true density and reversibility during charge / discharge can be enhanced.
- Lithium nickel composite oxide (a) includes Li-containing compounds (such as lithium hydroxide), Ni-containing compounds (such as nickel sulfate), Co-containing compounds (such as cobalt sulfate), Mn-containing compounds (such as manganese sulfate), and as required depending compound containing an element M 1 and (oxides, hydroxides, sulfates, etc.) may be mixed and prepared by, for example, firing the raw material mixture.
- Li-containing compounds such as lithium hydroxide
- Ni-containing compounds such as nickel sulfate
- Co-containing compounds such as cobalt sulfate
- Mn-containing compounds such as manganese sulfate
- lithium nickel composite oxide (a) in order to synthesize lithium nickel composite oxide (a) with higher purity, a composite compound containing a plurality of elements of Ni, Co, Mn, and element M 1 to be contained as required (hydroxide, It is preferable to mix an oxide or the like) with another raw material compound (Li-containing compound or the like), and to fire this raw material mixture.
- the firing condition of the raw material mixture for synthesizing the lithium nickel composite oxide (a) can be, for example, 800 to 1050 ° C. for 1 to 24 hours, but once it is lower than the firing temperature (for example, 250 to It is preferable to carry out preliminary heating by heating to 850 ° C. and holding at that temperature, and then proceed to the reaction by raising the temperature to the firing temperature. There is no particular limitation on the preheating time, but it is usually about 0.5 to 30 hours.
- the atmosphere during firing can be an atmosphere containing oxygen (that is, in the air), a mixed atmosphere of an inert gas (such as argon, helium, or nitrogen) and oxygen gas, or an oxygen gas atmosphere.
- the oxygen concentration (volume basis) is preferably 15% or more, and more preferably 18% or more.
- the positive electrode active material includes lithium cobalt oxide such as LiCoO 2 ; lithium manganese oxide such as LiMnO 2 and Li 2 MnO 3 ; lithium nickel oxide such as LiNiO 2 ; Lithium-containing composite oxide having a layered structure such as LiCo 1-x NiO 2 ; Lithium-containing composite oxide having a spinel structure such as LiMn 2 O 4 and Li 4/3 Ti 5/3 O 4 ; Olivine structure such as LiFePO 4 Lithium-containing composite oxides; oxides having the above-mentioned oxide as a basic composition and substituted with various elements (however, other than lithium-nickel composite oxides (a)); and the like are used together with lithium-nickel composite oxides (a) can do.
- lithium cobalt oxide such as LiCoO 2
- lithium manganese oxide such as LiMnO 2 and Li 2 MnO 3
- lithium nickel oxide such as LiNiO 2
- Lithium-containing composite oxide having a layered structure such as LiCo 1-x Ni
- the general composition formula Li 1 + o Co 1-pq Mg p M 2 q O 2 (where M 2 is Al, Ti, Fe, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Sn, Sr, At least one element selected from the group consisting of W, B, P and Bi, -0.3 ⁇ o ⁇ 0.3, 0.001 ⁇ p ⁇ 0.1, and 0 ⁇ q ⁇ 0.
- the lithium cobalt composite oxide (b) represented by 1) can also be used together with the lithium nickel composite oxide (a).
- Lithium cobalt composite oxide (b) contains Mg, and, due to its action, for example, stability in a high voltage region is higher than LiCoO 2 which is widely used as a positive electrode active material of a lithium secondary battery.
- the elution of metal (mainly Co) ions into the non-aqueous electrolyte hardly occurs in the battery, and the thermal stability is also high. Therefore, even when the lithium cobalt composite oxide (b) is used in combination with the lithium nickel composite oxide (a), it is highly stable even when charged at a high voltage, charge / discharge cycle characteristics, high temperature storage characteristics, load characteristics. Thus, a lithium secondary battery with better safety can be obtained.
- Co is a component that contributes to an increase in capacity of the lithium cobalt composite oxide (b).
- the lithium cobalt composite oxide (b) contains Mg and element M 2 in addition to Li, O and Co as shown in the general composition formula (the element M 2 may not be contained).
- the amount of Co is expressed by “1-pq” using the amount p of Mg and the amount q of element M 2 .
- the amount of Co “1-pq” in the lithium cobalt composite oxide (b) is preferably 0.9 or more and 0.95 or more from the viewpoint of increasing its capacity. Further, from the viewpoint of ensuring a good effect by adding Mg or the like, it is preferably 0.999 or less, and more preferably 0.05 or less.
- Mg has an effect of improving the stability of the lithium cobalt composite oxide (b) in the high voltage region and suppressing the elution of metal ions. It also has the effect of increasing the thermal stability of the composite oxide (b). Therefore, from the viewpoint of satisfactorily exerting the above-described action by Mg, in the general composition formula representing the lithium cobalt composite oxide (b), p representing the amount of Mg is preferably 0.001 or more, 0 More preferably, it is 0.002 or more.
- p representing the amount of Mg is preferably 0.1 or less, and more preferably 0.05 or less.
- lithium cobalt composite oxide (b) includes Al, Ti, Fe, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Sn, Sr, W, B, P and it may contain at least one element M 2 selected from the group consisting of Bi.
- q representing the amount of the element M 2 is preferably 0.1 or less, and more preferably 0.05 or less.
- lithium-cobalt composite oxide (b) is, as described above, may not contain the element M 2, in the general formula, the q indicating the amount of elemental M 2, is greater than zero.
- the lithium cobalt composite oxide (b) has a higher true density and a higher energy volume density, particularly when the composition is close to the stoichiometric ratio. ⁇ 0.3 ⁇ o ⁇ 0.3, and by adjusting the value of o in this way, the true density and reversibility during charging and discharging can be enhanced.
- the lithium-cobalt composite oxide (b) is composed of a Li-containing compound (such as lithium hydroxide), a Co-containing compound (such as cobalt sulfate), a Mg-containing compound (such as magnesium sulfate), and an element M 2 as necessary. It can be synthesized by mixing (oxide, hydroxide, sulfate, etc.) and firing this raw material mixture. In order to synthesize lithium cobalt composite oxide (b) with higher purity, a composite compound (hydroxide, oxide, etc.) containing Co and Mg, and further element M 2 as required, and a Li-containing compound It is preferable to sinter the raw material mixture.
- a Li-containing compound such as lithium hydroxide
- Co-containing compound such as cobalt sulfate
- Mg-containing compound such as magnesium sulfate
- element M 2 an element M 2 as necessary. It can be synthesized by mixing (oxide, hydroxide, sulfate, etc.) and
- the firing conditions of the raw material mixture for synthesizing the lithium cobalt composite oxide (b) can also be set to, for example, 800 to 1050 ° C. for 1 to 24 hours, as in the case of the lithium nickel composite oxide (a).
- the temperature is once lowered to a temperature (for example, 250 to 850 ° C.) lower than the calcination temperature, preliminarily heated by holding at that temperature, and then heated to the calcination temperature to advance the reaction.
- a temperature for example, 250 to 850 ° C.
- the atmosphere during firing can be an atmosphere containing oxygen (that is, in the air), a mixed atmosphere of an inert gas (such as argon, helium, or nitrogen) and oxygen gas, or an oxygen gas atmosphere.
- the oxygen concentration (volume basis) is preferably 15% or more, and more preferably 18% or more.
- the lithium cobalt composite oxide (b) is used for the other positive electrode active material when the lithium nickel composite oxide (a) and another positive electrode active material are used in combination.
- the content of the lithium nickel composite oxide (a) in the total amount of the positive electrode active material is preferably 10% by mass or more.
- the content of the lithium nickel composite oxide (a) in the total amount of the positive electrode active material Is 80 mass% or less [that is, the content of the lithium cobalt composite oxide (b) in the total amount of the positive electrode active material is 20 mass% or more].
- PVDF polyvinylidene fluoride
- PTFE polytetrafluoroethylene
- SBR styrene butadiene rubber
- CMC carboxymethyl cellulose
- the conductive auxiliary agent related to the positive electrode mixture layer for example, graphite (graphite carbon material) such as natural graphite (flaky graphite), artificial graphite; acetylene black, ketjen black, channel black, furnace black, Examples thereof include carbon blacks such as carbon blacks such as lamp black and thermal black; carbon fibers.
- the positive electrode for example, a paste-like or slurry-like positive electrode mixture-containing composition in which a positive electrode active material, a binder, a conductive auxiliary agent, and the like are dispersed in a solvent such as N-methyl-2-pyrrolidone (NMP) is prepared (
- NMP N-methyl-2-pyrrolidone
- the binder may be dissolved in a solvent), and this is applied to one or both sides of the current collector, dried, and then subjected to a calendering process as necessary.
- the positive electrode is not limited to those manufactured by the above manufacturing method, and may be manufactured by other methods.
- a lead body for electrical connection with other members in the lithium secondary battery may be formed on the positive electrode according to a conventional method, if necessary.
- the thickness of the positive electrode mixture layer is preferably, for example, 10 to 100 ⁇ m per one side of the current collector.
- the amount of the positive electrode active material is preferably 60 to 95% by mass
- the amount of the binder is preferably 1 to 15% by mass
- the amount of the conductive auxiliary agent Is preferably 3 to 20% by mass.
- the positive electrode current collector may be the same as that used for the positive electrode of a conventionally known lithium secondary battery, and for example, an aluminum foil having a thickness of 10 to 30 ⁇ m is preferable.
- a negative electrode mixture layer containing a negative electrode active material or a binder is used on one side or both sides of the current collector. Then, the negative active material according to the negative electrode, using the SiO x.
- the SiO x may contain Si microcrystal or amorphous phase.
- the atomic ratio of Si and O is a ratio including Si microcrystal or amorphous phase Si. That is, SiO x includes a structure in which Si (for example, microcrystalline Si) is dispersed in an amorphous SiO 2 matrix, and this amorphous SiO 2 is dispersed in the SiO 2 matrix. It is sufficient that the atomic ratio x satisfies 0.5 ⁇ x ⁇ 1.5 in combination with Si.
- x 1, so that the structural formula is represented by SiO.
- a material having such a structure for example, in X-ray diffraction analysis, a peak due to the presence of Si (microcrystalline Si) may not be observed, but when observed with a transmission electron microscope, the presence of fine Si Can be confirmed.
- SiO x is preferably a complex complexed with carbon materials, for example, it is desirable that the surface of the SiO x is coated with a carbon material.
- a conductive material conductive aid
- SiO x in the negative electrode is used. It is necessary to form an excellent conductive network by mixing and dispersing the material and the conductive material well. If complexes complexed with carbon material SiO x, for example, simply than with a material obtained by mixing a conductive material such as SiO x and the carbon material, good conductive network in the negative electrode Formed.
- the composite in which the surface of SiO x is coated with a carbon material is further combined with a conductive material (carbon material or the like), a better conductive network can be formed in the negative electrode. Therefore, it is possible to realize a lithium secondary battery with higher capacity and more excellent battery characteristics (for example, charge / discharge cycle characteristics).
- the complex of the SiO x and the carbon material coated with a carbon material for example, like granules the mixture was further granulated with SiO x and the carbon material coated with a carbon material.
- SiO x whose surface is coated with a carbon material the surface of a composite (for example, a granulated body) of SiO x and a carbon material having a smaller specific resistance value is further coated with a carbon material.
- a composite for example, a granulated body
- a carbon material having a smaller specific resistance value is further coated with a carbon material.
- Those can also be preferably used.
- a better conductive network can be formed. Therefore, in a lithium secondary battery having a negative electrode containing SiO x as a negative electrode active material, a heavy load Battery characteristics such as discharge characteristics can be further improved.
- Preferred examples of the carbon material that can be used to form a composite with SiO x include carbon materials such as low crystalline carbon, carbon nanotubes, and vapor grown carbon fibers.
- the details of the carbon material include at least one selected from the group consisting of fibrous or coiled carbon materials, carbon black (including acetylene black and ketjen black), artificial graphite, graphitizable carbon, and non-graphitizable carbon.
- a seed material is preferred.
- Fibrous or coil-like carbon materials are preferable in that they easily form a conductive network and have a large surface area.
- Carbon black (including acetylene black and ketjen black), graphitizable carbon, and non-graphitizable carbon have high electrical conductivity and high liquid retention, and even if SiO x particles expand and contract. This is preferable in that it has a property of easily maintaining contact with the particles.
- a graphitic carbon material as a negative electrode active material together with SiO x
- this graphitic carbon material is related to a composite of SiO x and a carbon material. It can also be used as a carbon material.
- Graphite carbon material like carbon black, has high electrical conductivity and high liquid retention, and even when SiO x particles expand and contract, they easily maintain contact with the particles. Therefore, it can be preferably used for forming a complex with SiO x .
- a fibrous carbon material is particularly preferable for use when the composite with SiO x is a granulated body. Fibrous carbon material can follow the expansion and contraction of SiO x with the charging and discharging of the battery due to the high shape is thin threadlike flexibility, also because bulk density is large, many and SiO x particles It is because it can have a junction.
- the fibrous carbon include polyacrylonitrile (PAN) -based carbon fiber, pitch-based carbon fiber, vapor-grown carbon fiber, and carbon nanotube, and any of these may be used.
- the fibrous carbon material can also be formed on the surface of the SiO x particles by, for example, a vapor phase method.
- the specific resistance value of SiO x is usually 10 3 to 10 7 k ⁇ cm, whereas the specific resistance value of the above-described carbon material is usually 10 ⁇ 5 to 10 k ⁇ cm.
- the composite of SiO x and the carbon material may further have a material layer (a material layer containing non-graphitizable carbon) that covers the carbon material coating layer on the particle surface.
- the ratio of SiO x and the carbon material is based on SiO x : 100 parts by mass from the viewpoint of satisfactorily exerting the effect of the composite with the carbon material.
- the carbon material is preferably 5 parts by mass or more, and more preferably 10 parts by mass or more. Further, in the composite, if the ratio of the carbon material to be combined with SiO x is too large, it may lead to a decrease in the amount of SiO x in the negative electrode mixture layer, and the effect of increasing the capacity may be reduced.
- SiO x relative to 100 parts by weight, the carbon material, and more preferably preferably not more than 50 parts by weight, more than 40 parts by weight.
- the composite of the SiO x and the carbon material can be obtained, for example, by the following method.
- a dispersion liquid in which SiO x is dispersed in a dispersion medium is prepared, and sprayed and dried to produce composite particles including a plurality of particles.
- a dispersion medium for example, ethanol or the like can be used as the dispersion medium. It is appropriate to spray the dispersion liquid in an atmosphere of 50 to 300 ° C.
- similar composite particles can be produced also by a granulation method by a mechanical method using a vibration type or planetary type ball mill or rod mill.
- the SiO x in the case of manufacturing a granulated body with small carbon material resistivity value than SiO x is adding the carbon material in the dispersion liquid of SiO x are dispersed in a dispersion medium, the dispersion by using a liquid, by a similar method to the case of composite of SiO x may be a composite particle (granule). Further, by granulation process according to the similar mechanical method, it is possible to produce a granular material of the SiO x and the carbon material.
- SiO x particles SiO x composite particles or a granulated body of SiO x and a carbon material
- a carbon material for example, the SiO x particles and the hydrocarbon-based material
- the gas is heated in the gas phase, and carbon generated by pyrolysis of the hydrocarbon-based gas is deposited on the surface of the particles.
- the hydrocarbon-based gas spreads to every corner of the composite particle, and the surface of the particle and the pores in the surface are thin and contain a conductive carbon material. Since a uniform film (carbon material coating layer) can be formed, the SiO x particles can be imparted with good conductivity with a small amount of carbon material.
- the processing temperature (atmosphere temperature) of the vapor deposition (CVD) method varies depending on the type of hydrocarbon gas, but usually 600 to 1200 ° C. is appropriate. Among these, the temperature is preferably 700 ° C. or higher, and more preferably 800 ° C. or higher. This is because the higher the treatment temperature, the less the remaining impurities, and the formation of a coating layer containing carbon having high conductivity.
- toluene As the liquid source of the hydrocarbon-based gas, toluene, benzene, xylene, mesitylene and the like can be used, but toluene that is easy to handle is particularly preferable.
- a hydrocarbon-based gas can be obtained by vaporizing them (for example, bubbling with nitrogen gas).
- methane gas, acetylene gas, etc. can also be used.
- SiO x particles SiO x composite particles or a granulated body of SiO x and a carbon material
- a carbon material by a vapor deposition (CVD) method
- a petroleum-based pitch or a coal-based pitch is used.
- At least one organic compound selected from the group consisting of a thermosetting resin and a condensate of naphthalene sulfonate and aldehydes is attached to a coating layer containing a carbon material, and then the organic compound is attached.
- the obtained particles may be fired.
- a dispersion liquid in which a SiO x particle (SiO x composite particle or a granulated body of SiO x and a carbon material) coated with a carbon material and the organic compound are dispersed in a dispersion medium is prepared, The dispersion is sprayed and dried to form particles coated with the organic compound, and the particles coated with the organic compound are fired.
- Isotropic pitch can be used as the pitch, and phenol resin, furan resin, furfural resin, or the like can be used as the thermosetting resin.
- phenol resin, furan resin, furfural resin, or the like can be used as the thermosetting resin.
- condensate of naphthalene sulfonate and aldehydes naphthalene sulfonic acid formaldehyde condensate can be used.
- a dispersion medium for dispersing the SiO x particles coated with the carbon material and the organic compound for example, water or alcohols (ethanol or the like) can be used. It is appropriate to spray the dispersion liquid in an atmosphere of 50 to 300 ° C.
- the firing temperature is usually 600 to 1200 ° C., preferably 700 ° C. or higher, and more preferably 800 ° C. or higher. This is because the higher the processing temperature, the less the remaining impurities, and the formation of a coating layer containing a high-quality carbon material with high conductivity. However, the processing temperature needs to be lower than the melting point of SiO x .
- a graphitic carbon material together with SiO x for the negative electrode active material according to the lithium secondary battery of the present invention.
- Examples of the graphitic carbon material used as the negative electrode active material together with SiO x include natural graphite such as scaly graphite; pyrolytic carbons, mesophase carbon microbeads (MCMB), carbon fiber and other graphitizable carbon at 2800 ° C. Examples thereof include artificial graphite graphitized as described above.
- the content of SiO x in the anode active material is 0.01 wt% or more It is preferably 3% by mass or more. Further, from the viewpoint of better avoiding the problem due to the volume change of the negative electrode due to charge / discharge, the content of SiO x in the negative electrode active material is preferably 30% by mass or less, and 20% by mass or less. Is more preferable.
- binder relating to the negative electrode mixture layer for example, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC) and the like are preferably used.
- PVDF polyvinylidene fluoride
- PTFE polytetrafluoroethylene
- SBR styrene butadiene rubber
- CMC carboxymethyl cellulose
- the negative electrode is prepared, for example, by preparing a negative electrode mixture-containing composition in which a negative electrode active material and a binder and, if necessary, a conductive additive are dispersed in a solvent such as NMP or water (however, the binder is dissolved in the solvent). It may be applied to one or both sides of the current collector, dried, and then subjected to a calendaring process as necessary.
- the negative electrode is not limited to those manufactured by the above manufacturing method, and may be manufactured by other manufacturing methods.
- the thickness of the negative electrode mixture layer is preferably 10 to 100 ⁇ m per one side of the current collector, and the density of the negative electrode mixture layer (the negative electrode mixture per unit area laminated on the current collector) (Calculated from the mass and thickness of the layer) is preferably 1.0 to 1.9 g / cm 3 .
- the amount of the negative electrode active material is preferably 80 to 95% by mass
- the amount of the binder is preferably 1 to 20% by mass
- a conductive assistant is used. In that case, the amount is preferably 1 to 10% by mass.
- the negative electrode current collector a copper or nickel foil, a punching metal, a net, an expanded metal, or the like can be used, but a copper foil is usually used.
- the upper limit of the thickness is preferably 30 ⁇ m, and the lower limit is 5 ⁇ m in order to ensure mechanical strength. Is desirable.
- the separator according to the lithium secondary battery of the present invention has a property that the pores are closed at 80 ° C. or higher (more preferably 100 ° C. or higher) and 170 ° C. or lower (more preferably 150 ° C. or lower) (that is, shutdown function). It is preferable that a separator used in a normal lithium secondary battery, for example, a microporous film made of polyolefin such as polyethylene (PE) or polypropylene (PP) can be used.
- the microporous film constituting the separator may be, for example, one using only PE or one using PP, or a laminate of a PE microporous film and a PP microporous film. There may be.
- the separator according to the lithium secondary battery of the present invention includes a porous layer (I) mainly composed of a resin having a melting point of 140 ° C. or lower, a resin that does not melt at a temperature of 150 ° C. or lower, or a heat resistant temperature of 150 ° C. or higher. It is preferable to use a laminated separator having a porous layer (II) mainly containing the inorganic filler.
- the “melting point” means the melting temperature measured using a differential scanning calorimeter (DSC) in accordance with the provisions of JIS K 7121.
- DSC differential scanning calorimeter
- does not melt at a temperature of 150 ° C. or lower means that the melting temperature measured using DSC exceeds 150 ° C. in accordance with the provisions of JIS K 7121. This means that the melting behavior is not exhibited at the temperature.
- the heat resistant temperature is 150 ° C. or higher” means that deformation such as softening is not observed at least at 150
- the porous layer (I) according to the multilayer separator is mainly for ensuring a shutdown function, and the melting point of the resin, which is a component in which the lithium secondary battery is the main component of the porous layer (I) When the temperature reaches the value, the resin related to the porous layer (I) melts to close the pores of the separator, thereby causing a shutdown that suppresses the progress of the electrochemical reaction.
- Examples of the resin having a melting point of 140 ° C. or lower, which is the main component of the porous layer (I), include PE, and the form thereof is a substrate such as a microporous film used in the above-described lithium secondary battery or a nonwoven fabric. And a dispersion obtained by applying a dispersion containing PE particles and drying.
- the volume of the resin having a main melting point of 140 ° C. or less is 50% by volume or more, and more preferably 70% by volume or more.
- the volume of the resin having a melting point of 140 ° C. or lower is 100% by volume.
- the porous layer (II) according to the multilayer separator has a function of preventing a short circuit due to direct contact between the positive electrode and the negative electrode even when the internal temperature of the lithium secondary battery is increased.
- the function is secured by a resin that does not melt at a temperature of °C or less or an inorganic filler with a heat resistant temperature of 150 °C or more. That is, when the battery becomes hot, even if the porous layer (I) shrinks, the porous layer (II) that does not easily shrink can cause the positive and negative electrodes directly when the separator is thermally contracted. It is possible to prevent a short circuit due to the contact of.
- this heat-resistant porous layer (II) acts as a skeleton of the separator, the thermal contraction of the porous layer (I), that is, the thermal contraction of the entire separator itself can be suppressed.
- the porous layer (II) is mainly composed of a resin having a melting point of 150 ° C. or higher, for example, a microporous film formed of a resin that does not melt at a temperature of 150 ° C. or lower (for example, the above-mentioned PP microporous for battery The film is laminated on the porous layer (I), and a dispersion containing resin particles that do not melt at a temperature of 150 ° C. or less is applied to the porous layer (I) and dried to form the porous layer (I).
- An application lamination type form in which the porous layer (II) is formed on the surface of the substrate is mentioned.
- Resins that do not melt at temperatures below 150 ° C include PP; crosslinked polymethyl methacrylate, crosslinked polystyrene, crosslinked polydivinylbenzene, crosslinked styrene-divinylbenzene copolymer, polyimide, melamine resin, phenolic resin, benzoguanamine-formaldehyde condensation And various crosslinked polymer fine particles; polysulfone; polyether sulfone; polyphenylene sulfide; polytetrafluoroethylene; polyacrylonitrile; aramid; polyacetal and the like.
- the average particle size is, for example, preferably 0.01 ⁇ m or more, more preferably 0.1 ⁇ m or more, It is preferably 10 ⁇ m or less, and more preferably 2 ⁇ m or less.
- the average particle size of the various particles referred to in the present specification is determined by, for example, using a laser scattering particle size distribution meter (for example, “LA-920” manufactured by HORIBA, Ltd.) and dispersing these fine particles in a medium that does not dissolve the resin.
- the measured average particle diameter D is 50%.
- porous layer (II) is formed mainly of an inorganic filler having a heat resistant temperature of 150 ° C. or higher, for example, a dispersion containing an inorganic filler having a heat resistant temperature of 150 ° C. or higher is applied to the porous layer (I).
- a dispersion containing an inorganic filler having a heat resistant temperature of 150 ° C. or higher is applied to the porous layer (I).
- the inorganic filler related to the porous layer (II) has a heat-resistant temperature of 150 ° C. or higher, is stable with respect to the nonaqueous electrolyte of the battery, and is electrochemically stable that is not easily oxidized or reduced in the battery operating voltage range.
- fine particles are preferable from the viewpoint of dispersion, and alumina, silica, and boehmite are preferable.
- Alumina, silica, and boehmite have high oxidation resistance, and the particle size and shape can be adjusted to the desired numerical values, making it easy to accurately control the porosity of the porous layer (II). It becomes.
- the thing of the said illustration may be used individually by 1 type, and may use 2 or more types together, for example.
- an inorganic filler having a heat resistant temperature of 150 ° C. may be used in combination with a resin that does not melt at a temperature of 150 ° C. or lower.
- the shape of the inorganic filler having a heat resistant temperature of 150 ° C. or higher related to the porous layer (II) is not particularly limited, and is substantially spherical (including true spherical), substantially elliptical (including elliptical), plate-like, etc. Various shapes can be used.
- the average particle diameter of the inorganic filler having a heat resistant temperature of 150 ° C. or higher related to the porous layer (II) is preferably 0.3 ⁇ m or more because the ion permeability is lowered if it is too small. More preferably, it is 5 ⁇ m or more.
- the average particle diameter is preferably 5 ⁇ m or less, and more preferably 2 ⁇ m or less.
- the resin that does not melt at a temperature of 150 ° C. or lower and the inorganic filler having a heat resistant temperature of 150 ° C. or higher are mainly contained in the porous layer (II).
- the amount in (II) [when the porous layer (II) contains only one of a resin that does not melt at a temperature of 150 ° C. or less and an inorganic filler that has a heat resistant temperature of 150 ° C. or more, is the amount, If both are included, the total amount. The same applies to the amount of the resin that does not melt at a temperature of 150 ° C. or less and the amount of the inorganic filler having a heat resistant temperature of 150 ° C.
- the porous layer (II) also contains an organic binder, a porous layer (II) of a resin that does not melt at a temperature of 150 ° C. or lower and an inorganic filler having a heat resistant temperature of 150 ° C. or higher. )
- the total volume of the constituent components of the porous layer (II) is preferably 99.5% by volume or less.
- porous layer (II) a resin that does not melt at a temperature of 150 ° C. or less, or an inorganic filler having a heat resistant temperature of 150 ° C. or more is bound, or the porous layer (II) and the porous layer (I) For integration or the like, it is preferable to contain an organic binder.
- Organic binders include ethylene-vinyl acetate copolymers (EVA, structural units derived from vinyl acetate of 20 to 35 mol%), ethylene-acrylic acid copolymers such as ethylene-ethyl acrylate copolymers, fluorine-based binders Examples include rubber, SBR, CMC, hydroxyethyl cellulose (HEC), polyvinyl alcohol (PVA), polyvinyl butyral (PVB), polyvinyl pyrrolidone (PVP), cross-linked acrylic resin, polyurethane, and epoxy resin.
- a heat-resistant binder having a heat-resistant temperature is preferably used.
- the organic binder those exemplified above may be used singly or in combination of two or more.
- highly flexible binders such as EVA, ethylene-acrylic acid copolymer, fluorine rubber, and SBR are preferable.
- highly flexible organic binders include “Evaflex Series (EVA)” by Mitsui DuPont Polychemical Co., Ltd., EVA by Nippon Unicar Co., Ltd., “Evaflex-EEA Series (Ethylene) by Mitsui DuPont Polychemical Co., Ltd.
- the organic binder when used for the porous layer (II), it can be used in the form of an emulsion dissolved or dispersed in the solvent for the composition for forming the porous layer (II) described later. Good.
- the coating laminate type separator is, for example, a composition for forming a porous layer (II) containing a resin particle that does not melt at a temperature of 150 ° C. or lower, an inorganic filler having a heat resistant temperature of 150 ° C. or higher (liquid such as slurry).
- the composition etc.) can be applied to the surface of the microporous membrane for constituting the porous layer (I) and dried at a predetermined temperature to form the porous layer (II).
- the composition for forming the porous layer (II) contains resin particles that do not melt at a temperature of 150 ° C. or lower and / or an inorganic filler having a heat resistant temperature of 150 ° C. or higher, and an organic binder as necessary. Is dispersed in a solvent (including a dispersion medium; the same shall apply hereinafter). The organic binder can be dissolved in a solvent.
- the solvent used in the composition for forming the porous layer (II) can uniformly disperse resin particles and inorganic filler that do not melt at a temperature of 150 ° C. or lower, and can dissolve or disperse the organic binder uniformly.
- organic solvents such as aromatic hydrocarbons such as toluene, furans such as tetrahydrofuran, ketones such as methyl ethyl ketone and methyl isobutyl ketone are preferably used.
- alcohols ethylene glycol, propylene glycol, etc.
- various propylene oxide glycol ethers such as monomethyl acetate may be appropriately added to these solvents.
- water may be used as a solvent.
- alcohols methyl alcohol, ethyl alcohol, isopropyl alcohol, ethylene glycol, etc.
- the composition for forming the porous layer (II) has a solid content containing, for example, a resin particle that does not melt at a temperature of 150 ° C. or lower and / or an inorganic filler having a heat resistant temperature of 150 ° C. or higher, and an organic binder. It is preferable to set it to 80 mass%.
- the porous layer (I) and the porous layer (II) do not have to be one each, and a plurality of layers may be present in the separator.
- a configuration in which the porous layer (I) is disposed on both sides of the porous layer (II) or a configuration in which the porous layer (II) is disposed on both sides of the porous layer (I) may be employed.
- increasing the number of layers may increase the thickness of the separator and increase the internal resistance of the battery or decrease the energy density. Therefore, it is not preferable to increase the number of layers.
- the total number of the porous layers (I) and (II) is preferably 5 or less.
- the thickness of the separator (the separator made of a microporous membrane made of polyolefin or the laminated separator) according to the lithium secondary battery of the present invention is preferably 10 to 30 ⁇ m, for example.
- the thickness of the porous layer (II) [when the separator has a plurality of porous layers (II), the total thickness] is determined by each of the functions of the porous layer (II). From the viewpoint of exhibiting more effectively, it is preferably 3 ⁇ m or more. However, if the porous layer (II) is too thick, the energy density of the battery may be lowered. Therefore, the thickness of the porous layer (II) is preferably 8 ⁇ m or less.
- the thickness of the porous layer (I) [when the separator has a plurality of porous layers (I), the total thickness thereof. same as below. ] Is preferably 6 ⁇ m or more, and more preferably 10 ⁇ m or more, from the viewpoint of more effectively exerting the above-described action (particularly shutdown action) by using the porous layer (I).
- the porous layer (I) is too thick, there is a possibility that the energy density of the battery may be lowered.
- the force that the porous layer (I) tends to shrink is increased, and the heat of the entire separator is increased. There is a possibility that the action of suppressing the shrinkage becomes small. Therefore, the thickness of the porous layer (I) is preferably 25 ⁇ m or less, more preferably 20 ⁇ m or less, and further preferably 14 ⁇ m or less.
- the porosity of the separator as a whole is preferably 30% or more in a dried state in order to secure the amount of electrolyte solution retained and to improve ion permeability.
- the separator porosity is preferably 70% or less in a dry state.
- the porosity of the separator: P (%) can be calculated by calculating the sum of each component i from the thickness of the separator, the mass per area, and the density of the constituent components using the following equation (3).
- a i ratio of component i when the total mass is 1
- ⁇ i density of component i (g / cm 3 )
- m mass per unit area of the separator (G / cm 2 )
- t thickness (cm) of the separator.
- m is the mass per unit area (g / cm 2 ) of the porous layer (I)
- t is the thickness of the porous layer (I) ( cm)
- the porosity: P (%) of the porous layer (I) can also be obtained using the formula (3).
- the porosity of the porous layer (I) obtained by this method is preferably 30 to 70%.
- the porosity of the porous layer (II) obtained by this method is preferably 20 to 60%.
- the separator preferably has a high mechanical strength, for example, a puncture strength of 3N or more is preferable.
- a puncture strength of 3N or more is preferable.
- Si and Sn alloys and oxides contribute to an increase in capacity of a battery as a negative electrode active material having a large capacity, but have a large volume change due to charge and discharge. Therefore, when such a negative electrode active material is used, mechanical damage is also applied to the facing separator due to expansion and contraction of the entire negative electrode by repeating charge and discharge. If the piercing strength of the separator is 3N or more, good mechanical strength is ensured, and mechanical damage to the separator can be reduced.
- Examples of the separator having a puncture strength of 3N or more include the above-described laminated separator, and in particular, an inorganic filler having a heat resistant temperature of 150 ° C. or higher in the porous layer (I) mainly composed of a resin having a melting point of 140 ° C. or lower.
- a separator in which a porous layer (II) containing as a main component is laminated is preferable. This is probably because the mechanical strength of the inorganic filler is high, so that the mechanical strength of the entire separator can be increased by supplementing the mechanical strength of the porous layer (I).
- the piercing strength can be measured by the following method.
- a separator is fixed on a plate having a hole with a diameter of 2 inches so as not to be wrinkled or bent, and a semispherical metal pin having a tip diameter of 1.0 mm is lowered onto a measurement sample at a speed of 120 mm / min.
- an average value is calculated
- the positive electrode, the negative electrode, and the separator are formed in the form of a laminated electrode body in which a separator is interposed between the positive electrode and the negative electrode, or a wound electrode body in which the separator is wound in a spiral shape. It can be used for the lithium secondary battery of the invention.
- the laminated separator particularly the porous layer (I) mainly composed of a resin having a melting point of 140 ° C. or less, mainly comprises an inorganic filler having a heat resistant temperature of 150 ° C. or more.
- the porous layer (II) is disposed so as to face at least the positive electrode.
- the porous layer (II) which mainly contains an inorganic filler having a heat-resistant temperature of 150 ° C.
- the porous layer (I) faces the negative electrode.
- the thermoplastic resin melted from the layer (I) is suppressed from being absorbed by the electrode mixture layer, and can be efficiently used to close the pores of the separator.
- Examples of the form of the lithium secondary battery of the present invention include a cylindrical shape (such as a square cylindrical shape or a cylindrical shape) using a steel can or an aluminum can as an outer can. Moreover, it can also be set as the soft package battery which used the laminated film which vapor-deposited the metal as an exterior body.
- the upper limit voltage at the time of charging before use may be about 4.2 V, which is adopted in a normal lithium secondary battery, but is charged at a high voltage of 4.3 V or more. Even the method can be used stably.
- Example 1 Preparation of positive electrode> Li 1.0 Ni 0.5 Co 0.2 Mn 0.3 O 2 [lithium nickel composite oxide (a)] and Li 1.036 Co 0.991 Al 0.004 Mg 0.002 Sr 0.001 Ti 100 parts by mass of a positive electrode active material obtained by mixing 0.002 Zr 0.001 O 2 [lithium cobalt composite oxide (b)] at a ratio (mass ratio) of 3: 7, and 10 parts by mass of PVDF as a binder.
- NMP solution contained at a concentration of 1%, 1 part by weight of artificial graphite and 1 part by weight of ketjen black, which are conductive assistants, are kneaded using a biaxial kneader, and NMP is added to adjust the viscosity
- NMP solution contained at a concentration of 1%
- 1 part by weight of artificial graphite and 1 part by weight of ketjen black, which are conductive assistants, are kneaded using a biaxial kneader, and NMP is added to adjust the viscosity
- ketjen black which are conductive assistants
- ⁇ Production of negative electrode> A composite in which the surface of SiO having an average particle diameter D50% of 8 ⁇ m, which is a negative electrode active material, is coated with a carbon material (the amount of the carbon material in the composite is 10% by mass), and graphite having an average particle diameter D50% of 16 ⁇ m
- ⁇ Preparation of non-aqueous electrolyte> In a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC) in a volume ratio of 3: 7, LiPF 6 is dissolved at a concentration of 1.1 mol / L, and an amount of adiponitrile is 0.1% by mass, A nonaqueous electrolyte was prepared by adding EDPA in an amount of 1.25% by mass, FEC in an amount of 2.0% by mass, and VC in an amount of 2.0% by mass.
- EC ethylene carbonate
- DEC diethyl carbonate
- the belt-like positive electrode is stacked on the belt-like negative electrode through a separator having a thickness of 16 ⁇ m or less, wound in a spiral shape, and then pressed so as to be flattened so that the electrode is wound in a flat winding structure.
- the electrode winding body was fixed with a polypropylene insulating tape.
- the electrode winding body is inserted into a prismatic battery case made of aluminum alloy having an outer dimension of thickness 4.0 mm, width 34 mm, and height 50 mm, and the lead body is welded. Was welded to the open end of the battery case.
- the non-aqueous electrolyte is injected from the inlet provided in the cover plate, and left for 1 hour, and then the inlet is sealed.
- the lithium secondary battery having the structure shown in FIG. Obtained.
- ⁇ Preparation of separator> Add 5 kg of ion-exchanged water and 0.5 kg of a dispersant (aqueous polycarboxylic acid ammonium salt, solid content concentration 40 mass%) to 5 kg of boehmite with an average particle diameter D50% of 1 ⁇ m, and have an internal volume of 20 L and 40 turns.
- a dispersion was prepared by pulverizing with a ball mill for 10 hours per minute. The treated dispersion was vacuum-dried at 120 ° C. and observed with a scanning electron microscope (SEM). As a result, the boehmite was almost plate-shaped.
- PE microporous separator for a lithium secondary battery (porous layer (I): thickness 12 ⁇ m, porosity 40%, average pore diameter 0.08 ⁇ m, PE melting point 135 ° C.) on one side corona discharge treatment (discharge amount 40 W) ⁇ Min / m 2 ), a porous layer (II) forming slurry is applied to the treated surface by a micro gravure coater, and dried to form a porous layer (II) having a thickness of 4 ⁇ m.
- a separator was obtained.
- the mass per unit area of the porous layer (II) in this separator was 5.5 g / m 2 , the boehmite volume content was 95% by volume, and the porosity was 45%.
- FIG. 1A is a plan view
- FIG. 1B is a partial cross-sectional view thereof.
- As shown in FIG. 2 is spirally wound through the separator 3 and then pressed so as to be flattened and accommodated in a rectangular (rectangular tube) battery case 4 together with a nonaqueous electrolyte as a flat electrode winding body 6.
- a metal foil, a non-aqueous electrolyte, and the like as a current collector used for manufacturing the positive electrode 1 and the negative electrode 2 are not illustrated.
- the battery case 4 is made of an aluminum alloy and constitutes a battery outer body.
- the battery case 4 also serves as a positive electrode terminal.
- An insulator 5 made of a PE sheet is disposed at the bottom of the battery case 4, and is connected to one end of each of the positive electrode 1 and the negative electrode 2 from the flat electrode winding body 6 made of the positive electrode 1, the negative electrode 2, and the separator 3.
- the positive electrode lead body 7 and the negative electrode lead body 8 thus drawn are drawn out.
- a stainless steel terminal 11 is attached to a sealing lid plate 9 made of aluminum alloy for sealing the opening of the battery case 4 via a polypropylene insulating packing 10, and an insulator 12 is attached to the terminal 11.
- a stainless steel lead plate 13 is attached.
- the cover plate 9 is inserted into the opening of the battery case 4, and the joint of the two is welded, whereby the opening of the battery case 4 is sealed and the inside of the battery is sealed.
- a non-aqueous electrolyte inlet 14 is provided in the lid plate 9, and the non-aqueous electrolyte inlet 14 is welded by, for example, laser welding with a sealing member inserted.
- the battery is sealed to ensure the hermeticity of the battery (therefore, in the battery of FIGS. 1 and 2, the nonaqueous electrolyte inlet 14 is actually a nonaqueous electrolyte inlet and a sealing member. , For ease of explanation, shown as non-aqueous electrolyte inlet 14).
- the lid plate 9 is provided with a cleavage vent 15 as a mechanism for discharging the internal gas to the outside when the temperature of the battery rises.
- the outer can 5 and the cover plate 9 function as a positive electrode terminal by directly welding the positive electrode lead body 7 to the lid plate 9, and the negative electrode lead body 8 is welded to the lead plate 13,
- the terminal 11 functions as a negative electrode terminal by connecting the negative electrode lead body 8 and the terminal 11 through the lead plate 13, but depending on the material of the battery case 4, the sign may be reversed. There is also.
- FIG. 2 is a perspective view schematically showing the external appearance of the battery shown in FIG. 1.
- FIG. 2 is shown for the purpose of showing that the battery is a square battery.
- FIG. 1 schematically shows a battery, and only specific members of the battery are shown. Also in FIG. 1, the inner peripheral portion of the electrode body is not cross-sectional.
- Example 2 A non-aqueous electrolyte was prepared in the same manner as in Example 1 except that the addition amount of adiponitrile was changed to 0.25% by mass. A lithium secondary secondary was prepared in the same manner as in Example 1 except that this non-aqueous electrolyte was used. A battery was produced.
- Example 3 A non-aqueous electrolyte was prepared in the same manner as in Example 1 except that the amount of adiponitrile added was changed to 0.5% by mass. A lithium secondary secondary was prepared in the same manner as in Example 1 except that this non-aqueous electrolyte was used. A battery was produced.
- Example 4 A nonaqueous electrolyte was prepared in the same manner as in Example 1 except that the addition amount of adiponitrile was changed to 1.0% by mass, and the lithium secondary secondary was prepared in the same manner as in Example 1 except that this nonaqueous electrolyte was used. A battery was produced.
- Example 5 A non-aqueous electrolyte was prepared in the same manner as in Example 1 except that the amount of adiponitrile added was changed to 2.5% by mass. A lithium secondary secondary was prepared in the same manner as in Example 1 except that this non-aqueous electrolyte was used. A battery was produced.
- Example 6 A non-aqueous electrolyte was prepared in the same manner as in Example 1 except that the addition amount of adiponitrile was changed to 5.0% by mass. A lithium secondary secondary was prepared in the same manner as in Example 1 except that this non-aqueous electrolyte was used. A battery was produced.
- Example 7 A nonaqueous electrolyte was prepared in the same manner as in Example 1 except that the amount of adiponitrile added was changed to 0.5% by mass and EPDA was not added, and Example 1 except that this nonaqueous electrolyte was used. In the same manner, a lithium secondary battery was produced.
- Example 8 A non-aqueous electrolyte was prepared in the same manner as in Example 1 except that the addition amount of adiponitrile was changed to 7.5% by mass, and a lithium secondary secondary was prepared in the same manner as in Example 1 except that this non-aqueous electrolyte was used. A battery was produced.
- Example 9 A nonaqueous electrolyte was prepared in the same manner as in Example 4 except that adiponitrile was changed to succinonitrile, and a lithium secondary battery was prepared in the same manner as in Example 4 except that this nonaqueous electrolyte was used.
- Example 10 A non-aqueous electrolyte was prepared in the same manner as in Example 4 except that EDPA was changed to PDPA, and a lithium secondary battery was prepared in the same manner as in Example 4 except that this non-aqueous electrolyte was used.
- Comparative Example 1 A non-aqueous electrolyte was prepared in the same manner as in Example 1 except that adiponitrile was not added, and a lithium secondary battery was produced in the same manner as in Example 1 except that this non-aqueous electrolyte was used.
- each battery after the initial capacity measurement was charged under the same conditions as the initial capacity measurement to obtain a fully charged state. Then, each battery in a fully charged state is discharged by 5% of the rated capacity (DOD 5%) at a current value of 1.0 C at 50 ° C., and charged to a fully charged state again at a current value of 1.0 C. A series of operations was taken as one cycle, and 800 cycles of charge / discharge were repeated. For each subsequent battery, charge / discharge was performed under the same conditions as the initial capacity measurement, and the capacity of each battery after 800 cycles was measured. The value obtained by dividing this by the initial capacity was expressed as a percentage, and the capacity maintenance rate was Asked.
- This 50 ° C / DOD 5% test is a test in which only a small part of the capacity is discharged and the battery is fully charged until the battery is fully charged. It is a thing. Therefore, it means that the higher the capacity maintenance rate in this test, the higher the stability even when the battery is used in a method of continuously charging.
- This test also assumes a usage method that continuously charges, and batteries that have not been short-circuited after this test have high stability even when used continuously. Means.
- a constant current charge is performed up to 4.35V at a current value of 1C, and then a constant voltage charge is performed at a voltage of 4.35V (constant current charging and constant voltage charging).
- the total charge time was 2.5 hours), and then a series of operations for discharging to 3.0 V at a current value of 1 C was taken as one cycle, and 500 cycles of charge and discharge were repeated.
- charge and discharge were performed under the same conditions as the initial capacity measurement, and the discharge capacity of each battery after 500 cycles was measured. The value obtained by dividing this by the initial capacity was expressed as a percentage.
- the maintenance rate was determined. It can be said that the higher the capacity retention rate, the better the charge / discharge cycle characteristics of the battery.
- Each battery after charging was placed in a thermostatic bath, and the bath temperature was set to 85 ° C. and left for 24 hours. Then, each battery was taken out from the thermostat, allowed to cool to room temperature, measured for thickness, and calculated the difference from the initial thickness (4.0 mm) to determine the amount of swelling of the battery after the storage test. .
- Table 1 shows the content of each additive in the nonaqueous electrolyte used in the lithium secondary batteries of Examples and Comparative Examples, and Table 2 shows the evaluation results.
- a non-aqueous electrolyte containing a compound using lithium nickel composite oxide (a) as a positive electrode active material, SiO as a negative electrode active material, and having a nitrile group in the molecule The lithium secondary batteries of Examples 1 to 10 used had a capacity in a 50 ° C./DOD 5% test as compared with the battery of Comparative Example 1 using a nonaqueous electrolyte containing no compound having a nitrile group in the molecule.
- the maintenance rate is high, and no short circuit occurs after continuous charging. Therefore, the lithium secondary batteries of Examples 1 to 10 can be used stably even if the method is such that charging is continued continuously at a high voltage of 4.3 V or higher. Furthermore, the lithium secondary batteries of Examples 1 to 10 have good load characteristics.
- the lithium secondary batteries of Examples 1 to 6, 8, 9, and 10 using the non-aqueous electrolyte that also contains the phosphonoacetate compound represented by the general formula (1) are non-aqueous batteries that do not contain the lithium secondary batteries. Compared to the battery of Example 7 using an electrolyte, the amount of swelling after the storage test is small, and the storage characteristics are also excellent.
- the lithium secondary batteries of Examples 1 to 7, 9, and 10 using the nonaqueous electrolyte in which the content of the compound having a nitrile group in the molecule is suitable use the nonaqueous electrolyte having a very high content.
- the capacity retention rate at the time of charge / discharge cycle characteristics evaluation is high, and the charge / discharge cycle characteristics are also excellent.
- the lithium secondary battery of the present invention can be used stably even if it is continuously charged, it can be suitably used for a power source application of a portable electronic device that is likely to be used in such a method. It can be used for the same applications as various applications to which conventionally known lithium secondary batteries are applied.
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Abstract
Description
トリメチル ホスホノフォルメート、メチル ジエチルホスホノフォルメート、メチル ジプロピルホスホノフォルメート、メチル ジブチルホスホノフォルメート、トリエチル ホスホノフォルメート、エチル ジメチルホスホノフォルメート、エチル ジプロピルホスホノフォルメート、エチル ジブチルホスホノフォルメート、トリプロピル ホスホノフォルメート、プロピル ジメチルホスホノフォルメート、プロピル ジエチルホスホノフォルメート、プロピル ジブチルホスホノフォルメート、トリブチル ホスホノフォルメート、ブチル ジメチルホスホノフォルメート、ブチル ジエチルホスホノフォルメート、ブチル ジプロピルホスホノフォルメート、メチル ビス(2,2,2-トリフルオロエチル)ホスホノフォルメート、エチル ビス(2,2,2-トリフルオロエチル)ホスホノフォルメート、プロピル ビス(2,2,2-トリフルオロエチル)ホスホノフォルメート、ブチル ビス(2,2,2-トリフルオロエチル)ホスホノフォルメートなど。 <Compound wherein n = 0 in the general formula (1)>
Trimethyl phosphonoformate, methyl diethylphosphonoformate, methyl dipropylphosphonoformate, methyl dibutylphosphonoformate, triethyl phosphonoformate, ethyl dimethylphosphonoformate, ethyl dipropylphosphonoformate, ethyl Dibutyl phosphonoformate, tripropyl phosphonoformate, propyl dimethylphosphonoformate, propyl diethylphosphonoformate, propyl dibutylphosphonoformate, tributyl phosphonoformate, butyl dimethylphosphonoformate, butyl diethylphospho Noformate, butyl dipropylphosphonoformate, methyl bis (2,2,2-trifluoroethyl) phosphonoformate, ethyl bis (2 2,2-trifluoroethyl) phosphonoacetate formate, propyl bis (2,2,2-trifluoroethyl) phosphonoacetate formate, and butyl bis (2,2,2-trifluoroethyl) phosphonoacetate formate.
トリメチル ホスホノアセテート、メチル ジエチルホスホノアセテート、メチル ジプロピルホスホノアセテート、メチル ジブチルホスホノアセテート、トリエチル ホスホノアセテート、エチル ジメチルホスホノアセテート、エチル ジプロピルホスホノアセテート、エチル ジブチルホスホノアセテート、トリプロピル ホスホノアセテート、プロピル ジメチルホスホノアセテート、プロピル ジエチルホスホノアセテート、プロピル ジブチルホスホノアセテート、トリブチル ホスホノアセテート、ブチル ジメチルホスホノアセテート、ブチル ジエチルホスホノアセテート、ブチル ジプロピルホスホノアセテート、メチル ビス(2,2,2-トリフルオロエチル)ホスホノアセテート、エチル ビス(2,2,2-トリフルオロエチル)ホスホノアセテート、プロピル ビス(2,2,2-トリフルオロエチル)ホスホノアセテート、ブチル ビス(2,2,2-トリフルオロエチル)ホスホノアセテート、アリル ジメチルホスホノアセテート、アリル ジエチルホスホノアセテート、2-プロピニル ジメチルホスホノアセテート、2-プロピニル ジエチルホスホノアセテートなど。 <Compound with n = 1 in the general formula (1)>
Trimethyl phosphonoacetate, methyl diethyl phosphonoacetate, methyl dipropyl phosphonoacetate, methyl dibutyl phosphonoacetate, triethyl phosphonoacetate, ethyl dimethylphosphonoacetate, ethyl dipropylphosphonoacetate, ethyl dibutylphosphonoacetate, tripropyl Phosphonoacetate, propyl dimethylphosphonoacetate, propyl diethylphosphonoacetate, propyl dibutylphosphonoacetate, tributyl phosphonoacetate, butyldimethylphosphonoacetate, butyldiethylphosphonoacetate, butyldipropylphosphonoacetate, methylbis (2 , 2,2-trifluoroethyl) phosphonoacetate, ethyl bis (2,2,2-trifluoroethyl) phos No acetate, propyl bis (2,2,2-trifluoroethyl) phosphonoacetate, butyl bis (2,2,2-trifluoroethyl) phosphonoacetate, allyl dimethylphosphonoacetate, allyl diethylphosphonoacetate, 2 -Propynyl dimethylphosphonoacetate, 2-propynyl diethylphosphonoacetate, etc.
トリメチル 3-ホスホノプロピオネート、メチル 3-(ジエチルホスホノ)プロピオネート、メチル 3-(ジプロピルホスホノ)プロピオネート、メチル 3-(ジブチルホスホノ)プロピオネート、トリエチル 3-ホスホノプロピオネート、エチル 3-(ジメチルホスホノ)プロピオネート、エチル 3-(ジプロピルホスホノ)プロピオネート、エチル 3-(ジブチルホスホノ)プロピオネート、トリプロピル 3-ホスホノプロピオネート、プロピル 3-(ジメチルホスホノ)プロピオネート、プロピル 3-(ジエチルホスホノ)プロピオネート、プロピル 3-(ジブチルホスホノ)プロピオネート、トリブチル 3-ホスホノプロピオネート、ブチル 3-(ジメチルホスホノ)プロピオネート、ブチル 3-(ジエチルホスホノ)プロピオネート、ブチル 3-(ジプロピルホスホノ)プロピオネート、メチル 3-(ビス(2,2,2-トリフルオロエチル)ホスホノ)プロピオネート、エチル 3-(ビス(2,2,2-トリフルオロエチル)ホスホノ)プロピオネート、プロピル 3-(ビス(2,2,2-トリフルオロエチル)ホスホノ)プロピオネート、ブチル 3-(ビス(2,2,2-トリフルオロエチル)ホスホノ)プロピオネートなど。 <Compound wherein n = 2 in the general formula (1)>
Trimethyl 3-phosphonopropionate, methyl 3- (diethylphosphono) propionate, methyl 3- (dipropylphosphono) propionate, methyl 3- (dibutylphosphono) propionate, triethyl 3-phosphonopropionate, ethyl 3- (dimethylphosphono) propionate, ethyl 3- (dipropylphosphono) propionate, ethyl 3- (dibutylphosphono) propionate, tripropyl 3-phosphonopropionate, propyl 3- (dimethylphosphono) propionate, Propyl 3- (diethylphosphono) propionate, propyl 3- (dibutylphosphono) propionate, tributyl 3-phosphonopropionate, butyl 3- (dimethylphosphono) propionate, butyl 3- (diethylphosphono) propyl Pionate, butyl 3- (dipropylphosphono) propionate, methyl 3- (bis (2,2,2-trifluoroethyl) phosphono) propionate, ethyl 3- (bis (2,2,2-trifluoroethyl) phosphono ) Propionate, propyl 3- (bis (2,2,2-trifluoroethyl) phosphono) propionate, butyl 3- (bis (2,2,2-trifluoroethyl) phosphono) propionate, and the like.
トリメチル 4-ホスホノブチレート、メチル 4-(ジエチルホスホノ)ブチレート、メチル 4-(ジプロピルホスホノ)ブチレート、メチル 4-(ジブチルホスホノ)ブチレート、トリエチル 4-ホスホノブチレート、エチル 4-(ジメチルホスホノ)ブチレート、エチル 4-(ジプロピルホスホノ)ブチレート、エチル 4-(ジブチルホスホノ)ブチレート、トリプロピル 4-ホスホノブチレート、プロピル 4-(ジメチルホスホノ)ブチレート、プロピル 4-(ジエチルホスホノ)ブチレート、プロピル ジブチルホスホノ)ブチレート、トリブチル 4-ホスホノブチレート、ブチル 4-(ジメチルホスホノ)ブチレート、ブチル 4-(ジエチルホスホノ)ブチレート、ブチル 4-(ジプロピルホスホノ)ブチレートなど。 <Compound wherein n = 3 in the general formula (1)>
Trimethyl 4-phosphonobutyrate, methyl 4- (diethylphosphono) butyrate, methyl 4- (dipropylphosphono) butyrate, methyl 4- (dibutylphosphono) butyrate, triethyl 4-phosphonobutyrate, ethyl 4- (Dimethylphosphono) butyrate, ethyl 4- (dipropylphosphono) butyrate, ethyl 4- (dibutylphosphono) butyrate, tripropyl 4-phosphonobutyrate, propyl 4- (dimethylphosphono) butyrate, propyl 4- (Diethylphosphono) butyrate, propyl dibutylphosphono) butyrate, tributyl 4-phosphonobutyrate, butyl 4- (dimethylphosphono) butyrate, butyl 4- (diethylphosphono) butyrate, butyl 4- (dipropylphosphono) ) Butyrate etc.
ぞれ1層ずつである必要はなく、複数の層がセパレータ中にあってもよい。例えば、多孔質層(II)の両面に多孔質層(I)を配置した構成としたり、多孔質層(I)の両面に多孔質層(II)を配置した構成としてもよい。ただし、層数を増やすことで、セパレータの厚みを増やして電池の内部抵抗の増加やエネルギー密度の低下を招く虞があるので、層数を多くしすぎるのは好ましくなく、前記積層型のセパレータ中の多孔質層(I)と多孔質層(II)との合計層数は5層以下であることが好ましい。 In the laminated separator, the porous layer (I) and the porous layer (II) do not have to be one each, and a plurality of layers may be present in the separator. For example, a configuration in which the porous layer (I) is disposed on both sides of the porous layer (II) or a configuration in which the porous layer (II) is disposed on both sides of the porous layer (I) may be employed. However, increasing the number of layers may increase the thickness of the separator and increase the internal resistance of the battery or decrease the energy density. Therefore, it is not preferable to increase the number of layers. The total number of the porous layers (I) and (II) is preferably 5 or less.
P ={1-(m/t)/(Σai・ρi)}×100 (3)
ここで、前記(3)式中、ai:全体の質量を1としたときの成分iの比率、ρi:成分iの密度(g/cm3)、m:セパレータの単位面積あたりの質量(g/cm2)、t:セパレータの厚み(cm)である。 The porosity of the separator as a whole is preferably 30% or more in a dried state in order to secure the amount of electrolyte solution retained and to improve ion permeability. On the other hand, from the viewpoint of securing separator strength and preventing internal short circuit, the separator porosity is preferably 70% or less in a dry state. The porosity of the separator: P (%) can be calculated by calculating the sum of each component i from the thickness of the separator, the mass per area, and the density of the constituent components using the following equation (3).
P = {1- (m / t) / (Σa i · ρ i )} × 100 (3)
Here, in the formula (3), a i : ratio of component i when the total mass is 1, ρ i : density of component i (g / cm 3 ), m: mass per unit area of the separator (G / cm 2 ), t: thickness (cm) of the separator.
<正極の作製>
Li1.0Ni0.5Co0.2Mn0.3O2〔リチウムニッケル複合酸化物(a)〕とLi1.036Co0.991Al0.004Mg0.002Sr0.001Ti0.002Zr0.001O2〔リチウムコバルト複合酸化物(b)〕とを3:7の割合(質量比)で混合した正極活物質100質量部と、結着剤であるPVDFを10質量%の濃度で含むNMP溶液20質量部と、導電助剤である人造黒鉛1質量部およびケッチェンブラック1質量部とを、二軸混練機を用いて混練し、更にNMPを加えて粘度を調節して、正極合剤含有ペーストを調製した。 Example 1
<Preparation of positive electrode>
Li 1.0 Ni 0.5 Co 0.2 Mn 0.3 O 2 [lithium nickel composite oxide (a)] and Li 1.036 Co 0.991 Al 0.004 Mg 0.002 Sr 0.001 Ti 100 parts by mass of a positive electrode active material obtained by mixing 0.002 Zr 0.001 O 2 [lithium cobalt composite oxide (b)] at a ratio (mass ratio) of 3: 7, and 10 parts by mass of PVDF as a binder. 20 parts by weight of NMP solution contained at a concentration of 1%, 1 part by weight of artificial graphite and 1 part by weight of ketjen black, which are conductive assistants, are kneaded using a biaxial kneader, and NMP is added to adjust the viscosity Thus, a positive electrode mixture-containing paste was prepared.
負極活物質である平均粒子径D50%が8μmであるSiO表面を炭素材料で被覆した複合体(複合体における炭素材料の量が10質量%)と、平均粒子径D50%が16μmである黒鉛とを、SiO表面を炭素材料で被覆した複合体の量が3.75質量%となる量で混合した混合物:97.5質量部と、結着剤であるSBR:1.5質量部と、増粘剤であるCMC:1質量部とに、水を加えて混合し、負極合剤含有ペーストを調製した。 <Production of negative electrode>
A composite in which the surface of SiO having an average particle diameter D50% of 8 μm, which is a negative electrode active material, is coated with a carbon material (the amount of the carbon material in the composite is 10% by mass), and graphite having an average particle diameter D50% of 16 μm A mixture in which the amount of the composite having the SiO surface coated with the carbon material is 3.75% by mass: 97.5 parts by mass, SBR as a binder: 1.5 parts by mass, CMC as a viscous agent was mixed with 1 part by mass of water to prepare a negative electrode mixture-containing paste.
エチレンカーボネート(EC)とジエチルカーボネート(DEC)との容積比3:7の混合溶媒に、LiPF6を1.1mol/Lの濃度で溶解させて、更にアジポニトリルを0.1質量%となる量、EDPAを1.25質量%となる量、FECを2.0質量%となる量、およびVCを2.0質量%となる量で、それぞれ添加して、非水電解質を調製した。 <Preparation of non-aqueous electrolyte>
In a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC) in a volume ratio of 3: 7, LiPF 6 is dissolved at a concentration of 1.1 mol / L, and an amount of adiponitrile is 0.1% by mass, A nonaqueous electrolyte was prepared by adding EDPA in an amount of 1.25% by mass, FEC in an amount of 2.0% by mass, and VC in an amount of 2.0% by mass.
前記帯状の正極を、厚みが16μmの以下に示すセパレータを介して前記帯状の負極に重ね、渦巻状に巻回した後、扁平状になるように加圧して扁平状巻回構造の電極巻回体とし、この電極巻回体をポリプロピレン製の絶縁テープで固定した。次に、外寸が厚み4.0mm、幅34mm、高さ50mmのアルミニウム合金製の角形の電池ケースに前記電極巻回体を挿入し、リード体の溶接を行うとともに、アルミニウム合金製の蓋板を電池ケースの開口端部に溶接した。その後、蓋板に設けた注入口から前記非水電解質を注入し、1時間静置した後注入口を封止して、図1に示す構造で、図2に示す外観のリチウム二次電池を得た。 <Battery assembly>
The belt-like positive electrode is stacked on the belt-like negative electrode through a separator having a thickness of 16 μm or less, wound in a spiral shape, and then pressed so as to be flattened so that the electrode is wound in a flat winding structure. The electrode winding body was fixed with a polypropylene insulating tape. Next, the electrode winding body is inserted into a prismatic battery case made of aluminum alloy having an outer dimension of thickness 4.0 mm, width 34 mm, and height 50 mm, and the lead body is welded. Was welded to the open end of the battery case. Thereafter, the non-aqueous electrolyte is injected from the inlet provided in the cover plate, and left for 1 hour, and then the inlet is sealed. The lithium secondary battery having the structure shown in FIG. Obtained.
平均粒子径D50%が1μmのベーマイト5kgに、イオン交換水5kgと、分散剤(水系ポリカルボン酸アンモニウム塩、固形分濃度40質量%)0.5kgとを加え、内容積20L、転回数40回/分のボールミルで10時間解砕処理をして分散液を調製した。処理後の分散液を120℃で真空乾燥し、走査型電子顕微鏡(SEM)で観察したところ、ベーマイトの形状はほぼ板状であった。 <Preparation of separator>
Add 5 kg of ion-exchanged water and 0.5 kg of a dispersant (aqueous polycarboxylic acid ammonium salt, solid content concentration 40 mass%) to 5 kg of boehmite with an average particle diameter D50% of 1 μm, and have an internal volume of 20 L and 40 turns. A dispersion was prepared by pulverizing with a ball mill for 10 hours per minute. The treated dispersion was vacuum-dried at 120 ° C. and observed with a scanning electron microscope (SEM). As a result, the boehmite was almost plate-shaped.
アジポニトリルの添加量を0.25質量%に変更した以外は、実施例1と同様にして非水電解質を調製し、この非水電解質を用いた以外は、実施例1と同様にしてリチウム二次電池を作製した。 Example 2
A non-aqueous electrolyte was prepared in the same manner as in Example 1 except that the addition amount of adiponitrile was changed to 0.25% by mass. A lithium secondary secondary was prepared in the same manner as in Example 1 except that this non-aqueous electrolyte was used. A battery was produced.
アジポニトリルの添加量を0.5質量%に変更した以外は、実施例1と同様にして非水電解質を調製し、この非水電解質を用いた以外は、実施例1と同様にしてリチウム二次電池を作製した。 Example 3
A non-aqueous electrolyte was prepared in the same manner as in Example 1 except that the amount of adiponitrile added was changed to 0.5% by mass. A lithium secondary secondary was prepared in the same manner as in Example 1 except that this non-aqueous electrolyte was used. A battery was produced.
アジポニトリルの添加量を1.0質量%に変更した以外は、実施例1と同様にして非水電解質を調製し、この非水電解質を用いた以外は、実施例1と同様にしてリチウム二次電池を作製した。 Example 4
A nonaqueous electrolyte was prepared in the same manner as in Example 1 except that the addition amount of adiponitrile was changed to 1.0% by mass, and the lithium secondary secondary was prepared in the same manner as in Example 1 except that this nonaqueous electrolyte was used. A battery was produced.
アジポニトリルの添加量を2.5質量%に変更した以外は、実施例1と同様にして非水電解質を調製し、この非水電解質を用いた以外は、実施例1と同様にしてリチウム二次電池を作製した。 Example 5
A non-aqueous electrolyte was prepared in the same manner as in Example 1 except that the amount of adiponitrile added was changed to 2.5% by mass. A lithium secondary secondary was prepared in the same manner as in Example 1 except that this non-aqueous electrolyte was used. A battery was produced.
アジポニトリルの添加量を5.0質量%に変更した以外は、実施例1と同様にして非水電解質を調製し、この非水電解質を用いた以外は、実施例1と同様にしてリチウム二次電池を作製した。 Example 6
A non-aqueous electrolyte was prepared in the same manner as in Example 1 except that the addition amount of adiponitrile was changed to 5.0% by mass. A lithium secondary secondary was prepared in the same manner as in Example 1 except that this non-aqueous electrolyte was used. A battery was produced.
アジポニトリルの添加量を0.5質量%に変更し、EPDAを添加しなかった以外は、実施例1と同様にして非水電解質を調製し、この非水電解質を用いた以外は、実施例1と同様にしてリチウム二次電池を作製した。 Example 7
A nonaqueous electrolyte was prepared in the same manner as in Example 1 except that the amount of adiponitrile added was changed to 0.5% by mass and EPDA was not added, and Example 1 except that this nonaqueous electrolyte was used. In the same manner, a lithium secondary battery was produced.
アジポニトリルの添加量を7.5質量%に変更した以外は、実施例1と同様にして非水電解質を調製し、この非水電解質を用いた以外は、実施例1と同様にしてリチウム二次電池を作製した。 Example 8
A non-aqueous electrolyte was prepared in the same manner as in Example 1 except that the addition amount of adiponitrile was changed to 7.5% by mass, and a lithium secondary secondary was prepared in the same manner as in Example 1 except that this non-aqueous electrolyte was used. A battery was produced.
アジポニトリルをスクシノニトリルに変更した以外は、実施例4と同様にして非水電解質を調製し、この非水電解質を用いた以外は実施例4と同様にしてリチウム二次電池を作成した。 Example 9
A nonaqueous electrolyte was prepared in the same manner as in Example 4 except that adiponitrile was changed to succinonitrile, and a lithium secondary battery was prepared in the same manner as in Example 4 except that this nonaqueous electrolyte was used.
EDPAをPDPAに変更した以外は、実施例4と同様にして非水電解質を調製し、この非水電解質を用いた以外は実施例4と同様にしてリチウム二次電池を作成した。 Example 10
A non-aqueous electrolyte was prepared in the same manner as in Example 4 except that EDPA was changed to PDPA, and a lithium secondary battery was prepared in the same manner as in Example 4 except that this non-aqueous electrolyte was used.
アジポニトリルを添加しなかった以外は、実施例1と同様にして非水電解質を調製し、この非水電解質を用いた以外は、実施例1と同様にしてリチウム二次電池を作製した。 Comparative Example 1
A non-aqueous electrolyte was prepared in the same manner as in Example 1 except that adiponitrile was not added, and a lithium secondary battery was produced in the same manner as in Example 1 except that this non-aqueous electrolyte was used.
実施例および比較例の電池について、1.0Cの電流値で4.35Vまで定電流充電を行い、続いて4.35Vの電圧で定電圧充電を行った。なお、定電流充電と定電圧充電の総充電時間は2.5時間とした。その後、0.2Cの電流値で3.0Vまで放電を行い、初期容量を測定した。 <50 ° C /
About the battery of an Example and a comparative example, the constant current charge was performed to 4.35V with the electric current value of 1.0C, and the constant voltage charge was subsequently performed with the voltage of 4.35V. The total charging time for constant current charging and constant voltage charging was 2.5 hours. Thereafter, the battery was discharged to 3.0 V at a current value of 0.2 C, and the initial capacity was measured.
実施例および比較例の各電池(50℃・DOD5%試験を行ったものとは別の電池)について、45℃で、1.0Cの電流値で4.4Vまで充電する定電流充電と、続いて4.4Vの電圧で定電圧充電を行う定電流-定電圧充電を継続し、500時間後の各電池の短絡の有無を調べた。 <Short-circuit test after continuous charging>
For each of the batteries of Examples and Comparative Examples (batteries different from those subjected to the 50 ° C./
実施例および比較例の各電池(前記の各評価を行ったものとは別の電池)について、50℃・DOD5%試験の初期容量測定と同じ条件で充放電を行って、初期容量を測定した。 <Charge / discharge cycle characteristics>
About each battery of an Example and a comparative example (battery different from what performed each said evaluation), it charged / discharged on the same conditions as the initial capacity measurement of a 50 degreeC and DOD5% test, and measured the initial capacity. .
実施例および比較例の電池(前記の各評価を行ったものとは別の電池)について、50℃・DOD5%試験の初期容量測定と同じ条件で充電を行った。充電後の各電池を恒温槽に入れ、槽内温度を85℃にして24時間放置した。その後、恒温槽から各電池を取り出し、室温になるまで放冷してから厚みを測定し、初期厚み(4.0mm)との差を算出して、貯蔵試験後の電池の膨れ量を求めた。 <Storage test>
About the battery of an Example and a comparative example (battery different from what performed said each evaluation), it charged on the same conditions as the initial stage capacity | capacitance measurement of a 50 degreeC * DOD5% test. Each battery after charging was placed in a thermostatic bath, and the bath temperature was set to 85 ° C. and left for 24 hours. Then, each battery was taken out from the thermostat, allowed to cool to room temperature, measured for thickness, and calculated the difference from the initial thickness (4.0 mm) to determine the amount of swelling of the battery after the storage test. .
実施例および比較例の電池(前記の各評価を行ったものとは別の電池)について、50℃・DOD5%試験の初期容量測定と同じ条件で充放電を行って放電容量(0.2C 放電容量)を測定した。また、0.2C放電容量測定後の各電池について、0.2C放電容量測定時と同じ条件で充電を行い、1.5Cの電流値で3.0Vまで放電を行って、放電容量(1.5C放電容量)を測定した。そして、各電池について、1.5C放電容量を0.2C放電容量で除した値を百分率で表して、容量維持率を求めた。この容量維持率が高いほど、電池の負荷特性が優れているといえる。 <Load characteristics>
The batteries of the examples and comparative examples (batteries different from those evaluated above) were charged and discharged under the same conditions as in the initial capacity measurement of the 50 ° C./
2 負極
3 セパレータ 1
Claims (10)
- 集電体の片面または両面に正極活物質を含有する正極合剤層を有する正極、集電体の片面または両面に負極活物質を含有する負極合剤層を有する負極、非水電解質およびセパレータを備えたリチウム二次電池であって、
前記正極の正極合剤層は、一般組成式Li1+yNi1-a-b-cCoaMnbM1 cO2〔ただし、M1はMg、Al、Ti、Fe、Cu、Zn、Ga、Ge、Zr、Nb、Mo、Sn、W、B、PおよびBiよりなる群から選択される少なくとも1種の元素であり、-0.15≦y≦0.15、0.05≦a≦0.3、0.05≦b≦0.3、0≦c≦0.03、およびa+b+c≦0.5である〕で表されるリチウムニッケル複合酸化物を、正極活物質として含有しており、
前記負極の負極合剤層は、SiとOとを構成元素に含む材料(ただし、Siに対するOの原子比xは、0.5≦x≦1.5である)を負極活物質として含有しており、
前記非水電解質は、分子内にニトリル基を有する化合物を含有していることを特徴とするリチウム二次電池。 A positive electrode having a positive electrode mixture layer containing a positive electrode active material on one side or both sides of a current collector, a negative electrode having a negative electrode mixture layer containing a negative electrode active material on one side or both sides of a current collector, a non-aqueous electrolyte, and a separator. A lithium secondary battery provided,
The positive electrode mixture layer of the positive electrode has a general composition formula Li 1 + y Ni 1-abc Co a Mn b M 1 c O 2 [where M 1 is Mg, Al, Ti, Fe, Cu, Zn, Ga , Ge, Zr, Nb, Mo, Sn, W, B, P, and Bi, at least one element selected from the group consisting of −0.15 ≦ y ≦ 0.15, 0.05 ≦ a ≦ 0.3, 0.05 ≦ b ≦ 0.3, 0 ≦ c ≦ 0.03, and a + b + c ≦ 0.5], as a positive electrode active material. ,
The negative electrode mixture layer of the negative electrode contains a material containing Si and O as constituent elements (however, the atomic ratio x of O to Si is 0.5 ≦ x ≦ 1.5) as a negative electrode active material. And
The non-aqueous electrolyte contains a compound having a nitrile group in the molecule, and is a lithium secondary battery. - 下記一般式(1)で表されるホスホノアセテート類化合物を、0.5~30質量%含有する非水電解質を使用した請求項1に記載のリチウム二次電池。
- 分子内にニトリル基を有する化合物の含有量が、0.1~5.0質量%の非水電解質を使用した請求項1または2に記載のリチウム二次電池。 3. The lithium secondary battery according to claim 1, wherein a non-aqueous electrolyte having a content of a compound having a nitrile group in the molecule is 0.1 to 5.0% by mass.
- 分子内にニトリル基を有する化合物は、分子内にニトリル基を2以上有している請求項1~3のいずれかに記載のリチウム二次電池。 4. The lithium secondary battery according to claim 1, wherein the compound having a nitrile group in the molecule has two or more nitrile groups in the molecule.
- 分子内にニトリル基を有する化合物が、アジポニトリルである請求項1~4のいずれかに記載のリチウム二次電池。 The lithium secondary battery according to any one of claims 1 to 4, wherein the compound having a nitrile group in the molecule is adiponitrile.
- 負極の負極合剤層は、SiとOとを構成元素に含む材料と炭素材料との複合体を含有している請求項1~5のいずれかに記載のリチウム二次電池。 6. The lithium secondary battery according to claim 1, wherein the negative electrode mixture layer of the negative electrode contains a composite of a material containing Si and O as constituent elements and a carbon material.
- 負極の負極合剤層は、負極活物質として黒鉛質炭素材料を更に含有している請求項1~6のいずれかに記載のリチウム二次電池。 The lithium secondary battery according to any one of claims 1 to 6, wherein the negative electrode mixture layer of the negative electrode further contains a graphitic carbon material as a negative electrode active material.
- ハロゲン置換された環状カーボネートを更に含有する非水電解質を使用した請求項1~7のいずれかに記載のリチウム二次電池。 The lithium secondary battery according to any one of claims 1 to 7, wherein a non-aqueous electrolyte further containing a halogen-substituted cyclic carbonate is used.
- ビニレンカーボネートを更に含有する非水電解質を使用した請求項1~8のいずれかに記載のリチウム二次電池。 The lithium secondary battery according to any one of claims 1 to 8, wherein a nonaqueous electrolyte further containing vinylene carbonate is used.
- 充電の上限電圧を4.3V以上に設定したものである請求項1~9のいずれかに記載のリチウム二次電池。 The lithium secondary battery according to any one of claims 1 to 9, wherein an upper limit voltage for charging is set to 4.3 V or more.
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Also Published As
Publication number | Publication date |
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KR101984810B1 (en) | 2019-05-31 |
JP6253411B2 (en) | 2017-12-27 |
CN108199035B (en) | 2021-05-28 |
KR20140105753A (en) | 2014-09-02 |
CN103975474A (en) | 2014-08-06 |
CN108199035A (en) | 2018-06-22 |
JPWO2013094465A1 (en) | 2015-04-27 |
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