WO2010106607A1 - 非水電解質二次電池用電極板及びその製造方法、並びに非水電解質二次電池 - Google Patents
非水電解質二次電池用電極板及びその製造方法、並びに非水電解質二次電池 Download PDFInfo
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- WO2010106607A1 WO2010106607A1 PCT/JP2009/006982 JP2009006982W WO2010106607A1 WO 2010106607 A1 WO2010106607 A1 WO 2010106607A1 JP 2009006982 W JP2009006982 W JP 2009006982W WO 2010106607 A1 WO2010106607 A1 WO 2010106607A1
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- positive electrode
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- electrolyte secondary
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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
- H01M4/64—Carriers or collectors
- H01M4/66—Selection of materials
- H01M4/661—Metal or alloys, e.g. alloy coatings
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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
- H01M10/058—Construction or manufacture
- H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
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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
- H01M4/04—Processes of manufacture in general
- H01M4/0402—Methods of deposition of the material
- H01M4/0404—Methods of deposition of the material by coating on electrode collectors
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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
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
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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
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
- H01M4/1391—Processes of manufacture of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
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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
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/621—Binders
- H01M4/622—Binders being polymers
- H01M4/623—Binders being polymers fluorinated polymers
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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
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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
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T29/00—Metal working
- Y10T29/49—Method of mechanical manufacture
- Y10T29/49002—Electrical device making
- Y10T29/49108—Electric battery cell making
- Y10T29/49115—Electric battery cell making including coating or impregnating
Definitions
- the present invention relates to an electrode plate for a non-aqueous electrolyte secondary battery, a method for manufacturing the same, and a non-aqueous electrolyte secondary battery.
- an active material such as lithium metal or lithium alloy, or a lithium ion host material (herein, “host material” refers to a material that can occlude and release lithium ions).
- This non-aqueous electrolyte secondary battery generally has a negative electrode in which the above negative electrode material is held by a negative electrode current collector that is a support thereof, and reversibly electrochemically reacts with lithium ions like a lithium cobalt composite oxide.
- the positive electrode active material that holds the positive electrode current collector that is the support, and the electrolyte solution, and is interposed between the negative electrode and the positive electrode to cause a short circuit between the negative electrode and the positive electrode
- a porous insulating layer (separator) is provided.
- the positive electrode and the negative electrode formed in a sheet shape or a foil shape are sequentially stacked via the porous insulating layer, or are wound in a spiral shape via the porous insulating layer to form a power generation element.
- the power generation element is housed in a battery case made of metal such as stainless steel, nickel-plated iron, or aluminum. And after pouring electrolyte solution in a battery case, a cover board is sealed and fixed to the opening edge part of a battery case, and a nonaqueous electrolyte secondary battery is comprised.
- the electrode plate tends to harden in both the positive electrode and the negative electrode.
- curing at the positive electrode is a factor that causes so-called electrode plate breakage in which the electrode plate cannot withstand the bending stress during winding when forming an electrode group in which the positive electrode, the negative electrode, and the separator are wound.
- the high-density positive electrode is subjected to a large rolling stress, the active material present on the surface of the electrode plate is cracked or crushed and has a very smooth surface.
- Such an electrode plate is very slippery with respect to the facing separator, and causes a slippage when the electrode plate group is formed, resulting in a failure factor.
- an object of the present invention is to provide a means for suppressing electrode plate breakage and cracking when forming an electrode group without reducing the capacity of the nonaqueous electrolyte secondary battery.
- an electrode plate for a nonaqueous electrolyte secondary battery is a nonaqueous electrolyte secondary battery in which an active material mixture layer including an active material and a binder is provided on a current collector.
- the electrode plate for a battery has a breaking elongation of 3% or more, a dynamic hardness of the surface of the active material mixture layer of 4.5 or more, and an internal dynamic hardness of 0. 0 than the surface. It is characterized by being 8 or larger.
- the active material may be a lithium-containing transition metal oxide
- the binder may be a polymer material containing fluorine.
- the current collector is preferably an aluminum alloy foil containing iron.
- the method for producing an electrode plate for a non-aqueous electrolyte secondary battery according to the present invention includes an active material mixture layer containing an active material that is a lithium-containing transition metal oxide and a binder that is a polymer material containing fluorine. Including a step A of forming on the current collector, which is an aluminum alloy foil containing, and a step B of heating the active material mixture layer to make the surface temperature of the active material mixture layer higher than the internal temperature. After the step B, the dynamic hardness of the surface of the active material mixture layer is 4.5 or more, and the internal dynamic hardness is 0.8 or more larger than the surface.
- the active material mixture layer can be pressed (abutted) against a heated roll to increase the surface temperature.
- the active material mixture layer can be pressed against (contacted with) the heated sheet to increase the surface temperature.
- the nonaqueous electrolyte secondary battery of the present invention is a nonaqueous electrolyte secondary battery in which any one of the above electrode plates for a nonaqueous electrolyte secondary battery is used as a positive electrode plate.
- the electrode plate for a non-aqueous electrolyte secondary battery and the method for manufacturing the same according to the present invention the electrode plate is cut without causing a decrease in battery capacity by performing a heat treatment on the surface of the electrode plate. In addition, it is possible to suppress the gap.
- the electrode plate is crushed by applying pressure to increase the density, and then the heating element is brought into contact with the electrode plate surface. It has been found that the use of a heat treatment means prevents the electrode plate from being cut and broken.
- the positive electrode is heated at a temperature higher than the recrystallization temperature of the binder and lower than its decomposition temperature.
- the technique of heat-processing any one electrode of a negative electrode is disclosed (for example, refer patent document 1).
- FIG. 1 is a schematic longitudinal sectional view showing the configuration of the nonaqueous electrolyte secondary battery according to Embodiment 1.
- the nonaqueous electrolyte secondary battery according to the present embodiment includes, for example, a stainless steel battery case 1 and an electrode group 8 accommodated in the battery case 1 as shown in FIG.
- An opening 1 a is formed on the upper surface of the battery case 1.
- a sealing plate 2 is caulked to the opening 1a via a gasket 3, whereby the opening 1a is sealed.
- the electrode group 8 includes a positive electrode 4, a negative electrode 5, and a porous insulating layer (separator) 6 made of, for example, polyethylene, and the positive electrode 4 and the negative electrode 5 are wound in a spiral shape via the separator 6. Configured.
- An upper insulating plate 7 a is disposed above the electrode group 8, and a lower insulating plate 7 b is disposed below the electrode group 8.
- One end of a positive electrode lead 4L made of aluminum is attached to the positive electrode 4, and the other end of the positive electrode lead 4L is connected to a sealing plate 2 that also serves as a positive electrode terminal.
- One end of a negative electrode lead 5L made of nickel is attached to the negative electrode 5, and the other end of the negative electrode lead 5L is connected to the battery case 1 which also serves as a negative electrode terminal.
- FIG. 2 is an enlarged cross-sectional view showing the configuration of the electrode group 8.
- the positive electrode 4 is an electrode plate having a positive electrode current collector 4A and a positive electrode mixture layer 4B as shown in FIG.
- the positive electrode current collector 4A is a conductive plate-like member, and specifically includes, for example, a member mainly made of aluminum.
- the positive electrode mixture layer 4B is provided on the surface (both sides) of the positive electrode current collector 4A, includes a positive electrode active material (for example, lithium composite oxide), includes a binder in addition to the positive electrode active material, and further includes a conductive agent. Etc. are preferably included.
- the negative electrode 5 is an electrode plate having a negative electrode current collector 5A and a negative electrode mixture layer 5B.
- the negative electrode current collector 5A is a conductive plate member.
- the negative electrode mixture layer 5B is provided on the surface (both sides) of the negative electrode current collector 5A, contains a negative electrode active material, and preferably contains a binder in addition to the negative electrode active material.
- the separator 6 is interposed between the positive electrode 4 and the negative electrode 5 as shown in FIG.
- the positive electrode current collector 4A a long conductive substrate having a porous structure or a nonporous structure is used.
- a metal foil mainly made of aluminum is used.
- an aluminum-iron alloy foil is preferable.
- the alloy preferably contains 1.0% to 2.0% by weight of iron. By using such an alloy foil, it becomes possible to perform a heat treatment while suppressing a decrease in capacity accompanying melting or softening of the binder.
- the thickness of the positive electrode current collector 4A is not particularly limited, but is preferably 1 ⁇ m or more and 500 ⁇ m or less, and more preferably 10 ⁇ m or more and 20 ⁇ m or less. Thus, by setting the thickness of the positive electrode current collector 4 ⁇ / b> A within the above range, the weight of the positive electrode 4 can be reduced while maintaining the strength of the positive electrode 4.
- the average particle diameter of the positive electrode active material is preferably 5 ⁇ m or more and 20 ⁇ m or less.
- the average particle diameter of the positive electrode active material is less than 5 ⁇ m, the surface area of the active material particles is extremely large, and the amount of the binder that satisfies the adhesive strength that can sufficiently handle the positive electrode plate becomes extremely large. For this reason, the amount of active material per electrode plate is reduced, and the capacity is reduced.
- the average particle diameter of the positive electrode active material is preferably 5 ⁇ m or more and 20 ⁇ m or less.
- binder examples include polyvinylidene fluoride (PVDF), polytetrafluoroethylene, polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamideimide, polyacrylonitrile, polyacrylic acid, and methyl polyacrylate.
- PVDF polyvinylidene fluoride
- aramid resin polyamide, polyimide, polyamideimide, polyacrylonitrile, polyacrylic acid, and methyl polyacrylate.
- Ester Polyacrylic acid ethyl ester, Polyacrylic acid hexyl ester, Polymethacrylic acid, Polymethacrylic acid methyl ester, Polymethacrylic acid ethyl ester, Polymethacrylic acid hexyl ester, Polyvinyl acetate, Polyvinylpyrrolidone, Polyether, Polyethersulfone , Hexafluoropolypropylene, styrene butadiene rubber, carboxymethyl cellulose and the like.
- PVDF and its derivatives are chemically stable in the nonaqueous electrolyte secondary battery, and sufficiently bind the positive electrode mixture layer 4B and the positive electrode current collector 4A.
- the positive electrode active material constituting the positive electrode mixture layer 4B, the binder, and the conductive agent are sufficiently bound together, good cycle characteristics and discharge performance can be obtained. Therefore, it is preferable to use PVDF or a derivative thereof as the binder of this embodiment.
- PVDF and its derivatives are preferable because they are inexpensive.
- PVDF polyvinyl styrene
- N-methylpyrrolidone N-methylpyrrolidone
- powdered PVDF is dissolved in a positive electrode mixture slurry. The case where it is made to use is mentioned.
- conductive agent examples include graphites such as natural graphite or artificial graphite, carbon blacks such as acetylene black (AB), ketjen black, channel black, furnace black, lamp black or thermal black, carbon fiber or metal.
- Conductive fibers such as fibers, metal powders such as carbon fluoride and aluminum, conductive whiskers such as zinc oxide or potassium titanate, conductive metal oxides such as titanium oxide, or organic conductivity such as phenylene derivatives Materials and the like.
- the negative electrode current collector 5A a long conductive substrate having a porous structure or a nonporous structure is used.
- the negative electrode current collector 5A include stainless steel, nickel, or copper.
- the thickness of the negative electrode current collector 5A is not particularly limited, but is preferably 1 ⁇ m or more and 500 ⁇ m or less, and more preferably 10 ⁇ m or more and 20 ⁇ m or less. Thus, by making the thickness of the negative electrode current collector 5A within the above range, the weight of the negative electrode 5 can be reduced while maintaining the strength of the negative electrode 5.
- the negative electrode mixture layer 5B preferably contains a binder in addition to the negative electrode active material.
- the negative electrode active material contained in the negative electrode mixture layer 5B will be described.
- ⁇ Negative electrode active material examples include metals, metal fibers, carbon materials, oxides, nitrides, silicon compounds, tin compounds, and various alloy materials.
- specific examples of the carbon material include, for example, various natural graphites, cokes, graphitizing carbon, carbon fibers, spherical carbon, various artificial graphites, and amorphous carbon.
- silicon compounds include, for example, SiO x (where 0.05 ⁇ x ⁇ 1.95), or B, Mg, Ni, Ti, Mo, Co, Ca, Cr, Cu, Fe, Mn, Examples thereof include a silicon alloy in which a part of Si is substituted with at least one element selected from the group consisting of Nb, Ta, V, W, Zn, C, N, and Sn, or a silicon solid solution.
- tin compound examples include Ni 2 Sn 4 , Mg 2 Sn, SnO x (where 0 ⁇ x ⁇ 2), SnO 2 , or SnSiO 3 .
- a negative electrode active material may be used individually by 1 type among the negative electrode active materials enumerated above, and may be used in combination of 2 or more type.
- a negative electrode in which the above-described silicon, tin, silicon compound, or tin compound is deposited in a thin film on the negative electrode current collector 5A can also be used.
- the separator 6 interposed between the positive electrode 4 and the negative electrode 5 examples include a microporous thin film, a woven fabric, or a non-woven fabric that has a large ion permeability and has a predetermined mechanical strength and insulation.
- a polyolefin such as polypropylene or polyethylene as the separator 6. Since polyolefin is excellent in durability and has a shutdown function, the safety of the lithium ion secondary battery can be improved.
- the thickness of the separator 6 is generally 10 ⁇ m or more and 300 ⁇ m or less, but preferably 10 ⁇ m or more and 40 ⁇ m or less.
- the thickness of the separator 6 is more preferably 15 ⁇ m or more and 30 ⁇ m or less, and further preferably 10 ⁇ m or more and 25 ⁇ m or less.
- the microporous thin film may be a single layer film made of one kind of material, or a composite film or multilayer film made of one kind or two or more kinds of materials. There may be.
- the porosity of the separator 6 is preferably 30% or more and 70% or less, and more preferably 35% or more and 60% or less. Here, the porosity indicates the ratio of the volume of the hole to the total volume of the separator.
- Nonaqueous electrolyte a liquid, gelled or solid nonaqueous electrolyte can be used.
- the liquid non-aqueous electrolyte includes an electrolyte (for example, a lithium salt) and a non-aqueous solvent that dissolves the electrolyte.
- an electrolyte for example, a lithium salt
- a non-aqueous solvent that dissolves the electrolyte.
- the gel-like non-aqueous electrolyte includes a non-aqueous electrolyte and a polymer material that holds the non-aqueous electrolyte.
- the polymer material include polyvinylidene fluoride, polyacrylonitrile, polyethylene oxide, polyvinyl chloride, polyacrylate, and polyvinylidene fluoride hexafluoropropylene.
- the solid nonaqueous electrolyte includes a polymer solid electrolyte.
- non-aqueous solvent for dissolving the electrolyte a known non-aqueous solvent can be used.
- the kind of this non-aqueous solvent is not specifically limited, For example, cyclic carbonate ester, chain
- specific examples of the cyclic carbonate include propylene carbonate (PC) and ethylene carbonate (EC).
- Specific examples of the chain carbonate ester include diethyl carbonate (DEC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), and the like.
- cyclic carboxylic acid ester examples include ⁇ -butyrolactone (GBL; gamma-butyrolactone) and ⁇ -valerolactone (GVL).
- GBL ⁇ -butyrolactone
- VL ⁇ -valerolactone
- the non-aqueous solvent one of the non-aqueous solvents listed above may be used alone, or two or more thereof may be used in combination.
- Examples of the electrolyte dissolved in the non-aqueous solvent include LiClO 4 , LiBF 4 , LiPF 6 , LiAlCl 4 , LiSbF 6 , LiSCN, LiCF 3 SO 3 , LiCF 3 CO 2 , LiAsF 6 , LiB 10 Cl 10 , and lower aliphatic carboxylic acid.
- Lithium acid, LiCl, LiBr, LiI, chloroborane lithium, borates, imide salts and the like are used.
- borate salts include, for example, lithium bis (1,2-benzenediolate (2-)-O, O ′) lithium borate, bis (2,3-naphthalenedioleate (2-)-O , O ′) lithium borate, bis (2,2′-biphenyldiolate (2-)-O, O ′) lithium borate, or bis (5-fluoro-2-olate-1-benzenesulfonic acid-O , O ′) lithium borate and the like.
- imide salts include, for example, lithium bistrifluoromethanesulfonate imide ((CF 3 SO 2 ) 2 NLi), lithium trifluoromethanesulfonate nonafluorobutanesulfonate (LiN (CF 3 SO 2 ) (C 4 F 9 SO 2)), or the like bispentafluoroethanesulfonyl imide lithium ((C 2 F 5 SO 2 ) 2 NLi) and the like.
- the electrolyte one of the electrolytes listed above may be used alone, or two or more may be used in combination.
- the amount of electrolyte dissolved in the non-aqueous solvent is preferably 0.5 mol / m 3 or more and 2 mol / m 3 or less.
- the nonaqueous electrolytic solution may contain an additive that decomposes on the negative electrode to form a film having high lithium ion conductivity and increases the charge / discharge efficiency of the battery.
- the additive having such a function include vinylene carbonate (VC), 4-methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, 4-ethyl vinylene carbonate, 4,5-diethyl vinylene carbonate, 4 -Propyl vinylene carbonate, 4,5-dipropyl vinylene carbonate, 4-phenyl vinylene carbonate, 4,5-diphenyl vinylene carbonate, vinyl ethylene carbonate (VEC), divinyl ethylene carbonate and the like.
- VEC vinyl ethylene carbonate
- An additive may be used individually by 1 type among the additives enumerated above, and may be used in combination of 2 or more type.
- at least one selected from the group consisting of vinylene carbonate, vinyl ethylene carbonate, and divinyl ethylene carbonate is preferable.
- a part of hydrogen atom of the additive enumerated above may be substituted with a fluorine atom.
- the non-aqueous electrolyte may contain, in addition to the electrolyte and the non-aqueous solvent, for example, a known benzene derivative that decomposes during overcharge to form a film on the electrode and inactivate the battery.
- a known benzene derivative that decomposes during overcharge to form a film on the electrode and inactivate the battery.
- the benzene derivative having such a function those having a phenyl group and a cyclic compound group adjacent to the phenyl group are preferable.
- specific examples of the benzene derivative include cyclohexylbenzene, biphenyl, diphenyl ether, and the like.
- cyclic compound group contained in the benzene derivative examples include, for example, a phenyl group, a cyclic ether group, a cyclic ester group, a cycloalkyl group, or a phenoxy group.
- a benzene derivative may be used individually by 1 type among the benzene derivatives enumerated above, and may be used in combination of 2 or more type.
- the content of the benzene derivative with respect to the nonaqueous solvent is preferably 10 vol% or less of the entire nonaqueous solvent.
- the configuration of the non-aqueous electrolyte secondary battery according to the present embodiment is not limited to the configuration shown in FIG.
- the nonaqueous electrolyte secondary battery according to the present embodiment is not limited to a cylindrical type as shown in FIG. 1, and may be a rectangular tube type or a high output type.
- the electrode group 8 is not limited to the configuration in which the positive electrode 4 and the negative electrode 5 are spirally wound via the separator 6 as shown in FIG. 1, and the positive electrode and the negative electrode are interposed via the separator. A stacked structure may be used.
- a lithium ion secondary battery will be described as a specific example as the nonaqueous electrolyte secondary battery according to the first embodiment, and a manufacturing method thereof will be described with reference to FIG. 1 described above.
- the manufacturing method of the positive electrode 4, the manufacturing method of the negative electrode 5, and the manufacturing method of a battery are demonstrated in order.
- the manufacturing method of the positive electrode 4 is as follows. For example, first, a positive electrode active material, a binder (as a binder, for example, PVDF, a derivative of PVDF, or a rubber binder is preferably used as described above) and a conductive agent are mixed with a liquid component. To prepare a positive electrode mixture slurry. Next, the obtained positive electrode mixture slurry is applied to the surface of a positive electrode current collector 4A made of a foil mainly containing aluminum and containing iron, and dried. Next, the positive electrode current collector 4A on which the positive electrode mixture slurry is applied and dried is rolled (compressed) to produce a positive electrode (positive electrode plate) having a predetermined thickness. Next, heat treatment is performed on the positive electrode at a predetermined temperature for a predetermined time.
- a binder for example, PVDF, a derivative of PVDF, or a rubber binder is preferably used as described above
- a conductive agent are mixed with a liquid component.
- a method of performing a heat treatment on the positive electrode for example, a method in which a hot roll heated to a predetermined temperature is brought into contact with the positive electrode, or two heated sheets are prepared, and the positive electrode is disposed between them.
- An example is a method in which a sheet is sandwiched between positive electrodes.
- the thermal history is inclined between the positive electrode mixture surface and the current collector side. That is, the surface is treated at a higher temperature, and the mixture on the side closer to the current collector is heat-treated at a relatively low temperature.
- the binder that adheres the positive electrode active materials to each other or the conductive agent softens or melts, and the mixture layer becomes brittle (dynamic hardness increases). Becomes higher.
- the positive electrode mixture layer there is a difference between the dynamic hardness of the surface portion and the internal dynamic hardness. As a result, it is difficult for slippage to occur due to slippage with respect to the separator in the group configuration.
- the positive electrode current collector is softened by heat treatment, and the electrode plate breakage can be suppressed by being easy to bend.
- the method for examining the softening of the positive electrode can be obtained by measuring the tensile elongation shown below.
- the electrode plate is cut into a width of 15 mm and an effective portion length of 20 mm to produce a measurement electrode plate 19 as shown in FIG.
- One end of the measurement electrode plate 19 is installed on the lower chuck 20b supported by the base 21, and a load cell (not shown, "load cell” is a load converter for converting a load into an electric signal).
- the measuring electrode plate 19 is gripped by installing the other end of the measuring electrode plate 19 on the upper chuck 20a connected to a load mechanism (not shown).
- the upper chuck 20a is moved at a speed of 20 mm / min along the length direction of the measurement electrode plate 19 (see the arrow shown in FIG. 3), and the measurement electrode plate 19 is pulled. Then, the length of the measurement electrode plate 19 immediately before being broken is measured, and the tensile elongation of the electrode plate is calculated from this length and the length of the measurement electrode plate 19 before being pulled (that is, 20 mm). Is done. Note that the tensile load acting on the measurement electrode plate 19 is detected by information from the load cell.
- the amount of the binder contained in the positive electrode mixture slurry is preferably 3.0 vol% or more and 6.0 vol% or less with respect to 100 vol% of the positive electrode active material.
- the amount of the binder contained in the positive electrode mixture layer is preferably 3.0 vol% or more and 6.0 vol% or less with respect to 100 vol% of the positive electrode active material.
- the manufacturing method of the negative electrode 5 is as follows. For example, first, a negative electrode active material and a binder are mixed with a liquid component to prepare a negative electrode mixture slurry. Next, the obtained negative electrode mixture slurry is applied to the surface of the negative electrode current collector 5A and dried. Next, the negative electrode current collector 5A having the negative electrode mixture slurry applied and dried on the surface thereof is rolled to prepare a negative electrode having a predetermined thickness. In addition, after rolling like the positive electrode, the negative electrode may be heat-treated at a predetermined temperature for a predetermined time.
- the battery manufacturing method is as follows. For example, as shown in FIG. 1, first, an aluminum positive electrode lead 4L is attached to a positive electrode current collector (see FIG. 2: 4A), and a nickel negative electrode lead 5L is attached to the negative electrode current collector (see FIG. 2: 5A). Install. Then, the positive electrode 4 and the negative electrode 5 are wound through the separator 6 between them, and the electrode group 8 is comprised. Next, the upper insulating plate 7 a is disposed at the upper end of the electrode group 8, while the lower insulating plate 7 b is disposed at the lower end of the electrode group 8.
- the negative electrode lead 5 ⁇ / b> L is welded to the battery case 1
- the positive electrode lead 4 ⁇ / b> L is welded to the sealing plate 2 having an internal pressure actuated safety valve, and the electrode group 8 is accommodated in the battery case 1.
- a nonaqueous electrolytic solution is injected into the battery case 1 by a decompression method.
- a battery is manufactured by caulking the opening end of the battery case 1 to the sealing plate 2 via the gasket 3.
- the characteristic points of the method for manufacturing the nonaqueous electrolyte secondary battery according to the present embodiment are as follows.
- the positive electrode mixture slurry was applied to both surfaces of an aluminum alloy foil having a thickness of 15 ⁇ m and containing 1.4% by weight of iron as a positive electrode current collector, and dried. Thereafter, the positive electrode current collector on which the positive electrode mixture slurry was applied and dried on both sides was rolled to obtain a plate-shaped positive electrode plate having a thickness of 0.157 mm.
- the positive electrode plate was heat-treated with a hot roll.
- the heat treatment by the hot roll is performed by bringing the hot roll heated to 200 ° C. into contact with the surface of the positive electrode plate for 3 seconds.
- the contact time that is, heat treatment time
- the surface temperature of the positive electrode plate can reach 190 ° C.
- This positive electrode plate was cut into a width of 57 mm and a length of 564 mm to obtain a positive electrode having a thickness of 0.157 mm, a width of 57 mm, and a length of 564 mm.
- the negative electrode mixture slurry was applied to both sides of a copper foil having a thickness of 8 ⁇ m as a negative electrode current collector and dried. Thereafter, the negative electrode current collector having the negative electrode mixture slurry applied and dried on both sides was rolled to obtain a plate-like negative electrode plate having a thickness of 0.156 mm.
- the negative electrode plate was heat-treated with hot air at 190 ° C. for 8 hours in a nitrogen atmosphere. Next, the negative electrode plate was cut into a width of 58.5 mm and a length of 750 mm to obtain a negative electrode having a thickness of 0.156 mm, a width of 58.5 mm, and a length of 750 mm.
- a positive electrode lead made of aluminum was attached to the positive electrode current collector, and a negative electrode lead made of nickel was attached to the negative electrode current collector. Thereafter, the positive electrode and the negative electrode were wound through a polyethylene separator between them to constitute an electrode group.
- an upper insulating film was disposed at the upper end of the electrode group, and a lower insulating plate was disposed at the lower end thereof.
- the negative electrode lead was welded to the battery case, and the positive electrode lead was welded to a sealing plate having an internal pressure actuated safety valve, and the electrode group was housed in the battery case.
- a non-aqueous electrolyte was poured into the battery case by a decompression method.
- the battery case was fabricated by caulking the open end of the battery case to a sealing plate via a gasket.
- battery 1 of the example a battery having a positive electrode that has been heat-treated by a hot roll at 200 ° C. for 3 seconds is referred to as battery 1 of the example.
- Battery 2 In the production of the positive electrode, a battery was produced in the same manner as the battery 1 except that the setting temperature of the heat roll was set to 250 ° C. and the time during which the positive electrode plate was in contact with the heat roll was set to 1 second. This is referred to as the battery 2 of the example.
- Battery 3 In the production of the positive electrode, a battery was produced in the same manner as the battery 1 except that the set temperature of the heat roll was set to 175 ° C. and the time during which the positive electrode plate was in contact with the heat roll was set to 30 seconds. This is referred to as the battery 3 of the example.
- Battery 4 In the production of the positive electrode, a battery was produced in the same manner as the battery 1 except that the set temperature of the heat roll was set to 200 ° C. and the time during which the positive electrode plate was in contact with the heat roll was set to 60 seconds. This is referred to as the battery 4 of Comparative Example 1.
- Battery 5 In the production of the positive electrode, a battery was produced in the same manner as the battery 1 except that the setting temperature of the heat roll was set to 250 ° C. and the time during which the positive electrode plate was in contact with the heat roll was set to 20 seconds. This is referred to as the battery 5 of Comparative Example 1.
- Battery 6 In the production of the positive electrode, a battery was produced in the same manner as the battery 1 except that the setting temperature of the heat roll was set to 175 ° C. and the time during which the positive electrode plate was in contact with the heat roll was set to 3 seconds. This is referred to as the battery 6 of Comparative Example 1.
- each of batteries 1 to 6 the characteristics of the positive electrode were evaluated.
- the tensile elongation (breaking elongation) of the positive electrode and the dynamic hardness of the positive electrode mixture layer were measured. Each measuring method is as follows.
- each battery was charged at a constant current of 1.45 A until the voltage reached 4.25 V, and charged continuously at a constant voltage of 4.25 V until the current reached 50 mA, and then the batteries were disassembled.
- the positive electrode was taken out.
- the taken out positive electrode was cut into a width of 15 mm and an effective portion length of 20 mm to produce a measurement positive electrode. While one end of the positive electrode for measurement was fixed, the other end was pulled along the length direction at a speed of 20 mm / min.
- Table 1 shows the tensile elongation (breaking elongation) of the positive electrodes constituting the batteries 1 to 6.
- the battery capacity measurement method is as follows.
- Each battery 1 to 6 is charged at a constant current of 1.4 A until the voltage reaches 4.2 V in an environment of 25 ° C., and is continuously charged until the current reaches 50 mA at a constant voltage of 4.2 V. After that, the capacity was measured when discharging was performed at a constant current of 0.56 A until the voltage reached 2.5V.
- the electrode plate breakage evaluation and the winding deviation evaluation were performed.
- the test method and evaluation method are as shown below.
- a battery was produced using a positive electrode material mixture slurry containing 2.5 vol% of rubber binder with respect to 100 vol% of the positive electrode active material, using a rubber binder (Nippon ZEON BM500B) instead of PVDF.
- the positive electrode binder is a rubber binder, and the positive electrode is manufactured in the same manner as the battery 1 except that the setting temperature of the heat roll is set to 200 ° C. and the time during which the positive electrode plate is in contact with the heat roll is set to 3 seconds. A battery was produced, and the produced battery is referred to as battery 7 of Comparative Example 2.
- Battery 8 In the production of the positive electrode, a battery was produced in the same manner as the battery 7 except that the setting temperature of the heat roll was set to 250 ° C. and the time during which the positive electrode plate was in contact with the heat roll was set to 1 second. This is referred to as the battery 8 of Example 2.
- Battery 9 In the production of the positive electrode, a battery was produced in the same manner as the battery 7 except that the setting temperature of the heat roll was set to 175 ° C. and the time during which the positive electrode plate was in contact with the heat roll was set to 30 seconds. This is referred to as the battery 9 of Example 2.
- the positive electrode current collector was made of pure aluminum foil, and in the production of the positive electrode, the same as battery 1 except that the set temperature of the heat roll was set to 200 ° C. and the time during which the positive electrode plate was in contact with the heat roll was set to 3 seconds. A battery was produced, and the produced battery is referred to as the battery 10 of Comparative Example 3.
- Battery 11 In the production of the positive electrode, a battery was produced in the same manner as the battery 10 except that the setting temperature of the heat roll was set to 250 ° C. and the time during which the positive electrode plate was in contact with the heat roll was set to 1 second. This is referred to as the battery 11 of Example 3.
- Battery 12 In the production of the positive electrode, a battery was produced in the same manner as the battery 10 except that the set temperature of the heat roll was set to 175 ° C. and the time during which the positive electrode plate was in contact with the heat roll was set to 30 seconds. This is referred to as the battery 12 of Example 3.
- Battery 13 In the production of the positive electrode, a battery was produced in the same manner as the battery 10 except that the set temperature of the heat roll was set to 200 ° C. and the time during which the positive electrode plate was in contact with the heat roll was set to 60 seconds. This is referred to as the battery 13 of Example 3.
- Battery 14 In the production of the positive electrode, a battery was produced in the same manner as the battery 10 except that the setting temperature of the heat roll was set to 250 ° C. and the time during which the positive electrode plate was in contact with the heat roll was set to 20 seconds. This is referred to as the battery 11 of Example 3.
- Battery 15 In the production of the positive electrode, a battery was produced in the same manner as the battery 10 except that the setting temperature of the heat roll was set to 175 ° C. and the time during which the positive electrode plate was in contact with the heat roll was set to 3 seconds. This is referred to as the battery 15 of Example 3.
- a battery was manufactured in the same manner as the battery 1 except that a heat treatment atmosphere furnace was used as the heat treatment equipment instead of the heat roll apparatus.
- the atmosphere inside the heat treatment atmosphere furnace was filled with nitrogen gas.
- Battery 17 In the production of the positive electrode, a battery was produced in the same manner as the battery 16 except that the set temperature of the heat treatment atmosphere furnace was set to 250 ° C. and the time for the positive electrode plate to pass through the atmosphere furnace was set to 1 second. This is referred to as the battery 17 of Comparative Example 4.
- Battery 18 In the production of the positive electrode, a battery was produced in the same manner as the battery 16 except that the set temperature of the heat treatment atmosphere furnace was set to 175 ° C. and the time for the positive electrode plate to pass through the atmosphere furnace was set to 30 seconds. This is referred to as the battery 18 of Comparative Example 4.
- Battery 19 In the production of the positive electrode, a battery was produced in the same manner as the battery 16 except that the set temperature of the heat treatment atmosphere furnace was set to 200 ° C. and the time for the positive electrode plate to pass through the atmosphere furnace was set to 60 seconds. This is referred to as the battery 19 of Comparative Example 4.
- Battery 20 In the production of the positive electrode, a battery was produced in the same manner as the battery 16 except that the set temperature of the heat treatment atmosphere furnace was set to 250 ° C. and the time for the positive electrode plate to pass through the atmosphere furnace was set to 20 seconds. This is referred to as the battery 20 of Comparative Example 4.
- Battery 21 In the production of the positive electrode, a battery was produced in the same manner as the battery 16 except that the set temperature of the heat treatment atmosphere furnace was set to 175 ° C. and the time for the positive electrode plate to pass through the atmosphere furnace was set to 3 seconds. This is referred to as the battery 21 of Comparative Example 4.
- Battery 23 A battery was prepared in the same manner as the battery 1 except that the binder of the positive electrode was used as a rubber binder, and the heat treatment operation with a hot roll was not performed in the preparation of the positive electrode.
- Comparative Example 5 when both the PVDF and rubber binders were examined, the same battery capacity was obtained. However, as shown in Table 5, the electrode plate breakage during the configuration and the leak inspection after the configuration were as shown in Table 5. Many defects were detected. This is because the positive electrode has a low elongation rate, and when the wound body is formed, it cannot withstand the stress and is cut off, and since the surface is smooth (when using PVDF), leakage due to slippage slippage from the separator is reversed. When the rubber binder is used, the active material is peeled off and leaks due to mixing inside the electrode group.
- the batteries 1 to 3 have a high capacity, and the effect is obtained without causing breakage of the electrode plate and leakage.
- the positive electrode plate has an elongation rate (breaking elongation) of 3% or more and good elongation, both the surface of the positive electrode mixture layer and the internal dynamic hardness are 4.5 or more, and the inside is more than the surface. This is because 0.8 is larger than 0.8.
- the capacity was reduced as compared with the batteries 1 to 3 of the example and the batteries 22 and 23 of the comparative example 5. This is presumably because the heat treatment was excessively performed, so that a larger amount of the binder was dissolved and softened than the positive electrodes of the batteries 1 to 3 and covered the active material surface. On the contrary, in the battery 6, the high capacity was maintained, but the electrode plate was cut and leaked. This is presumed to be due to the fact that the electrode plate has a lower elongation rate than the batteries 1 to 5, and the positive electrode plate surface has the same dynamic hardness as the inside, is less likely to collapse against the separator, and has less frictional force. is doing.
- Comparative Example 2 it was found that the dynamic hardness of the positive electrode plate was significantly reduced by changing the binder from PVDF to a rubber binder. For this reason, the whole plate became brittle, and the positive electrode active material was easily peeled off when the electrode group was constructed. Therefore, the number of leaks in the batteries 7 to 9 tended to increase.
- Comparative Example 3 pure aluminum foil is used as the positive electrode current collector, but since the softening temperature thereof is lower than that of the iron-aluminum alloy foil, higher temperature heat treatment is required. However, high-temperature or long-time heat treatment promotes thermal melting and softening of the binder, and thus tends to cause a decrease in capacity. As a result, in the batteries 10 to 12, the elongation was low and the electrode plate was frequently cut. Although the batteries 13 and 14 had a sufficient elongation rate for the structure, the entire positive electrode was heated by being exposed to a high temperature for a long time, and the dynamic hardness of the surface and the interior became substantially equal. As a result, the capacity is reduced.
- Comparative Example 4 when the atmosphere furnace is used for heating the positive electrode plate instead of the heat roll, the whole is heated, so the batteries 19 and 20 having sufficient elongation rate are heated too much and the capacity is reduced. did. On the contrary, in the batteries 16 to 18 and 21, the electrode plate was frequently cut due to insufficient heat treatment and insufficient elongation.
- a method for the heat treatment after rolling of the positive electrode plate and the negative electrode plate, a method may be employed in which hot air subjected to low humidity treatment is applied at a predetermined temperature.
- the present invention is useful for, for example, a consumer power source having a high energy density, a power source for mounting on a car, or a power source for large tools.
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Abstract
Description
図1は、実施形態1に係る非水電解質二次電池の構成について示す模式的な縦断面図である。
正極4を構成する正極集電体4A及び正極合剤層4Bのそれぞれについて順に説明する。
正極活物質としては、例えばLiCoO2、LiNiO2、LiMnO2、LiCoNiO2、LiCoMOz、LiNiMOz、LiNi1/3Co1/3Mn1/3O2、LiMn2O4、LiMnMO4、LiMePO4、Li2MePO4F(但し、M=Na、Mg、Sc、Y、Mn、Fe、Co、Ni、Cu、Zn、Al、Cr、Pb、Sb及びBのうちの少なくとも1つ、Me=Fe、Mn、Co、Niから選択される少なくとも1種を含む金属元素)が挙げられる、又はこれら含リチウム化合物の一部元素が異種元素で置換されたものが挙げられる。また、正極活物質として、金属酸化物、リチウム酸化物又は導電剤等で表面処理された正極活物質を用いても良く、表面処理としては例えば疎水化処理が挙げられる。
結着剤としては、例えばポリビニリデンフルオライド(PVDF:poly vinylidene fluoride)、ポリテトラフルオロエチレン、ポリエチレン、ポリプロピレン、アラミド樹脂、ポリアミド、ポリイミド、ポリアミドイミド、ポリアクリルニトリル、ポリアクリル酸、ポリアクリル酸メチルエステル、ポリアクリル酸エチルエステル、ポリアクリル酸ヘキシルエステル、ポリメタクリル酸、ポリメタクリル酸メチルエステル、ポリメタクリル酸エチルエステル、ポリメタクリル酸ヘキシルエステル、ポリ酢酸ビニル、ポリビニルピロリドン、ポリエーテル、ポリエーテルサルフォン、ヘキサフルオロポリプロピレン、スチレンブタジエンゴム又はカルボキシメチルセルロース等が挙げられる。または、テトラフルオロエチレン、ヘキサフルオロエチレン、ヘキサフルオロプロピレン、パーフルオロアルキルビニルエーテル、フッ化ビニリデン、クロロトリフルオロエチレン、エチレン、プロピレン、ペンタフルオロプロピレン、フルオロメチルビニルエーテル、アクリル酸及びヘキサジエンから選択された2種以上の材料を共重合させた共重合体、又は選択された2種以上の材料を混合した混合物が挙げられる。
導電剤としては、例えば天然黒鉛若しくは人造黒鉛等のグラファイト類、アセチレンブラック(AB:acetylene black)、ケッチェンブラック、チャンネルブラック、ファーネスブラック、ランプブラック若しくはサーマルブラック等のカーボンブラック類、炭素繊維若しくは金属繊維等の導電性繊維類、フッ化カーボン、アルミニウム等の金属粉末類、酸化亜鉛若しくはチタン酸カリウム等の導電性ウィスカー類、酸化チタン等の導電性金属酸化物、又はフェニレン誘導体等の有機導電性材料等が挙げられる。
負極5を構成する負極集電体5A及び負極合剤層5Bのそれぞれについて順に説明する。
負極活物質としては、例えば金属、金属繊維、炭素材料、酸化物、窒化物、珪素化合物、錫化合物又は各種合金材料等が挙げられる。これらのうち炭素材料の具体例としては、例えば各種天然黒鉛、コークス、黒鉛化途上炭素、炭素繊維、球状炭素、各種人造黒鉛又は非晶質炭素等が挙げられる。
正極4と負極5との間に介在されるセパレータ6としては、大きなイオン透過度を持ち、所定の機械的強度と絶縁性とを兼ね備えた微多孔薄膜、織布又は不織布等が挙げられる。特に、セパレータ6として、例えばポリプロピレン、ポリエチレン等のポリオレフィンを用いることが好ましい。ポリオレフィンは耐久性に優れ且つシャットダウン機能を有するため、リチウムイオン二次電池の安全性を向上させることができる。セパレータ6の厚さは、一般的に10μm以上300μm以下であるが、10μm以上40μm以下であることが好ましい。また、セパレータ6の厚さは、15μm以上30μm以下であることがより好ましく、10μm以上25μm以下であればさらに好ましい。また、セパレータ6として微多孔薄膜を用いる場合には、微多孔薄膜は、1種の材料からなる単層膜であってもよく、1種又は2種以上の材料からなる複合膜又は多層膜であってもよい。また、セパレータ6の空孔率は、30%以上70%以下であることが好ましく、35%以上60%以下であればさらに好ましい。ここで空孔率とは、セパレータの全体積に対する孔部の体積の比率を示す。
非水電解質としては、液状、ゲル状又は固体状の非水電解質を使用できる。
正極4の作製方法は次に示す通りである。例えば、まず、正極活物質、結着剤(結着剤としては、前述の通り、例えばPVDF、PVDFの誘導体、又はゴム系結着剤が好適に用いられる)及び導電剤を液状成分に混合させて正極合剤スラリーを調製する。次に、得られた正極合剤スラリーを、アルミニウムを主とし鉄を含む箔からなる正極集電体4Aの表面に塗布して乾燥させる。次に、表面に正極合剤スラリーが塗布乾燥された正極集電体4Aを圧延(圧縮)し、所定の厚さを有する正極(正極板)を作製する。次に、正極に対し、所定温度で所定時間の間、熱処理を施す。
負極5の作製方法は次に示す通りである。例えば、まず、負極活物質、及び結着剤を液状成分に混合させて負極合剤スラリーを調製する。次に、得られた負極合剤スラリーを、負極集電体5Aの表面に塗布して乾燥させる。次に、表面に負極合剤スラリーが塗布乾燥された負極集電体5Aを圧延し、所定の厚さを有する負極を作製する。なお、正極同様圧延後、負極に対し、所定温度の下・所定時間の間、熱処理を施してもよい。
電池の製造方法は次に示す通りである。例えば、まず、図1に示すように、正極集電体(図2:4A参照)にアルミニウム製の正極リード4Lを取り付け、負極集電体(図2:5A参照)にニッケル製の負極リード5Lを取り付ける。その後、正極4と負極5とを、それらの間にセパレータ6を介して捲回し、電極群8を構成する。次に、電極群8の上端に上部絶縁板7aを配置する一方、電極群8の下端に下部絶縁板7bを配置する。その後、負極リード5Lを電池ケース1に溶接すると共に、正極リード4Lを内圧作動型の安全弁を有する封口板2に溶接して、電極群8を電池ケース1内に収納する。その後、減圧方式により、電池ケース1内に非水電解液を注液する。最後に、電池ケース1の開口端部をガスケット3を介して封口板2にかしめることにより、電池を製造する。
実施例では、電池1~3を、比較例1では電池4~6を作製した。
(正極の作製)
まず、平均粒子径が10μmのLiNi0.82Co0.15Al0.03O2を準備した。
まず、平均粒子径が約20μmになるように、鱗片状人造黒鉛を粉砕及び分級した。
非水溶媒として体積比が1:3となるように混合されたエチレンカーボネートとジメチルカーボネートとからなる混合溶媒に、電池の充放電効率を高める添加剤として5wt%のビニレンカーボネートを添加すると共に、非水溶媒に対するモル濃度が1.4mol/m3となるように電解質としてLiPF6を溶解させて、非水電解液を得た。
まず、正極集電体にアルミニウム製の正極リードを取り付け、負極集電体にニッケル製の負極リードを取り付けた。その後、正極と負極とを、それらの間にポリエチレン製のセパレータを介して捲回し、電極群を構成した。
正極の作製において、熱ロールの設定温度を250℃、正極用板が熱ロールに接触している時間を1秒に設定した事以外は電池1と同様にして電池を作製し、作製した電池を実施例の電池2と称する。
正極の作製において、熱ロールの設定温度を175℃、正極用板が熱ロールに接触している時間を30秒に設定した事以外は電池1と同様にして電池を作製し、作製した電池を実施例の電池3と称する。
正極の作製において、熱ロールの設定温度を200℃、正極用板が熱ロールに接触している時間を60秒に設定した事以外は電池1と同様にして電池を作製し、作製した電池を比較例1の電池4と称する。
正極の作製において、熱ロールの設定温度を250℃、正極用板が熱ロールに接触している時間を20秒に設定した事以外は電池1と同様にして電池を作製し、作製した電池を比較例1の電池5と称する。
正極の作製において、熱ロールの設定温度を175℃、正極用板が熱ロールに接触している時間を3秒に設定した事以外は電池1と同様にして電池を作製し、作製した電池を比較例1の電池6と称する。
まず、各電池を、1.45Aの定電流で電圧が4.25Vに至るまで充電を行い、4.25Vの定電圧で電流が50mAになるまで続けて充電を行った後、電池を分解し、正極を取り出した。取り出した正極を、幅15mm,有効部長さ20mmに裁断し、測定用正極を作製した。測定用正極の一端を固定する一方、その他端を長さ方向に沿って20mm/minの速度で引っ張った。そして、破断される直前の測定用正極の長さを測定し、この長さと、引っ張る前の測定用正極の長さ(すなわち、20mm)とから、正極の引っ張り伸び率を算出した。各電池1~6を構成する正極の引っ張り伸び率(破断伸度)を表1に記す。
まず、各電池を、1.45Aの定電流で電圧が4.25Vに至るまで充電を行い、4.25Vの定電圧で電流が50mAになるまで続けて充電を行った後、電池を分解し、正極を取り出した。取り出した正極に対し、島津ダイナミック超微小硬度計DUH-W201を用いて、正極合剤層のダイナミック硬度を測定した。このとき、正極表面におけるダイナミック硬度を測定し、その後測定箇所の近傍において正極合剤層を、正極合剤層の厚みが約半分の厚みになるまで削った。その削った部分において合剤層内部におけるダイナミック硬度を測定した。その結果を各電池1~6を構成する正極について表1に記す。
各電池1~6を、25℃の環境下、1.4Aの定電流で電圧が4.2Vに至るまで充電を行い、4.2Vの定電圧で電流が50mAになるまで続けて充電を行った後、0.56Aの定電流で電圧が2.5Vに至るまで放電を行った時の容量を測定した。
3φの巻芯を用いて、0.12Nの張力をかけながら、正極と負極とを、それらの間にセパレータを介して捲回してセルを作製した。各電池それぞれ、50セルずつ作製した。そして、各電池において、50セルのうち捲回中に正極が切れたセル数(正極が切れたセル数/50セル)を確認した。各電池1~6での極板切れ評価の結果を、以下に示す表1に記す。
実際に電池を構成した後、電解液を注液する前に定電圧電源を用いて、250Vの電圧を印加し、リーク検査を行った。巻きずれが生じていればこのリーク検査によって不良と判断される。各電池それぞれ、50個ずつ準備した。それぞれの電池の50個のうちリークした数を確認した。その結果を表1に示す。
PVDFの代わりにゴムバインダー(日本ゼオンBM500B)を用いて、正極活物質100vol%に対して2.5vol%のゴムバインダーを含む正極合剤スラリーを用いて電池を作製した。
正極の結着剤をゴムバインダーにし、正極の作製において、熱ロールの設定温度を200℃、正極用板が熱ロールに接触している時間を3秒に設定した事以外は電池1と同様に電池を作製し、作製した電池を比較例2の電池7と称する。
正極の作製において、熱ロールの設定温度を250℃、正極用板が熱ロールに接触している時間を1秒に設定した事以外は電池7と同様に電池を作製し、作製した電池を比較例2の電池8と称する。
正極の作製において、熱ロールの設定温度を175℃、正極用板が熱ロールに接触している時間を30秒に設定した事以外は電池7と同様に電池を作製し、作製した電池を比較例2の電池9と称する。
次に集電体を鉄-アルミニウム合金箔の代わりに純アルミニウム箔を用いて、その他は電池1と同様に電池を作製した。
正極集電体を純アルミニウム箔にし、正極の作製において、熱ロールの設定温度を200℃、正極用板が熱ロールに接触している時間を3秒に設定した事以外は電池1と同様に電池を作製し、作製した電池を比較例3の電池10と称する。
正極の作製において、熱ロールの設定温度を250℃、正極用板が熱ロールに接触している時間を1秒に設定した事以外は電池10と同様に電池を作製し、作製した電池を比較例3の電池11と称する。
正極の作製において、熱ロールの設定温度を175℃、正極用板が熱ロールに接触している時間を30秒に設定した事以外は電池10と同様に電池を作製し、作製した電池を比較例3の電池12と称する。
正極の作製において、熱ロールの設定温度を200℃、正極用板が熱ロールに接触している時間を60秒に設定した事以外は電池10と同様に電池を作製し、作製した電池を比較例3の電池13と称する。
正極の作製において、熱ロールの設定温度を250℃、正極用板が熱ロールに接触している時間を20秒に設定した事以外は電池10と同様に電池を作製し、作製した電池を比較例3の電池11と称する。
正極の作製において、熱ロールの設定温度を175℃、正極用板が熱ロールに接触している時間を3秒に設定した事以外は電池10と同様に電池を作製し、作製した電池を比較例3の電池15と称する。
熱処理設備として熱ロール装置の代わりに熱処理雰囲気炉を用いて、その他は電池1と同様に電池を作製した。熱処理雰囲気炉の内部の雰囲気は窒素ガスで充満させた。
正極の作製において、ロールによる熱処理ではなく、熱処理雰囲気炉の設定温度を200℃、正極用板が前記雰囲気炉内を通過する時間を3秒に設定して熱処理を行った事以外は電池1と同様に電池を作製し、作製した電池を比較例4の電池16と称する。
正極の作製において、熱処理雰囲気炉の設定温度を250℃、正極用板が前記雰囲気炉内を通過する時間を1秒に設定した事以外は電池16と同様に電池を作製し、作製した電池を比較例4の電池17と称する。
正極の作製において、熱処理雰囲気炉の設定温度を175℃、正極用板が前記雰囲気炉内を通過する時間を30秒に設定した事以外は電池16と同様に電池を作製し、作製した電池を比較例4の電池18と称する。
正極の作製において、熱処理雰囲気炉の設定温度を200℃、正極用板が前記雰囲気炉内を通過する時間を60秒に設定した事以外は電池16と同様に電池を作製し、作製した電池を比較例4の電池19と称する。
正極の作製において、熱処理雰囲気炉の設定温度を250℃、正極用板が前記雰囲気炉内を通過する時間を20秒に設定した事以外は電池16と同様に電池を作製し、作製した電池を比較例4の電池20と称する。
正極の作製において、熱処理雰囲気炉の設定温度を175℃、正極用板が前記雰囲気炉内を通過する時間を3秒に設定した事以外は電池16と同様に電池を作製し、作製した電池を比較例4の電池21と称する。
(電池22)
正極の作製において、熱ロールによる熱処理操作を行わなかった以外は電池1と同様に電池を作製し、作製した比較例5の電池を電池22と称する。
正極の結着剤をゴムバインダーにし、正極の作製において、熱ロールによる熱処理操作を行わなかった以外は電池1と同様に電池を作製し、作製した電池を比較例5の電池23と称する。
正極板、負極板の圧延後の熱処理には、所定温度の下、低湿度処理を施した熱風により行う方法を採用してもよい。
2 封口板
3 ガスケット
4 正極
4A 正極集電体
4B 正極合剤層
4L 正極リード
5 負極
5A 負極集電体
5B 負極合剤層
5L 負極リード
6 セパレータ(多孔質絶縁層)
7a 上部絶縁板
7b 下部絶縁板
8 電極群
9 正極
9A 正極集電体
9B 正極合剤層
10 クラック
11 正極
11A 正極集電体
11B 正極合剤層
12 クラック
19 測定用正極
20a 上側チャック
20b 下側チャック
21 基台
Claims (7)
- 集電体上に活物質と結着剤とを含む活物質合剤層が設けられた非水電解質二次電池用電極板であって、
破断伸度が3%以上であり、
前記活物質合剤層の表面のダイナミック硬度が4.5以上であり、且つ内部のダイナミック硬度の方が表面よりも0.8以上大きいことを特徴とする非水電解質二次電池用電極板。 - 前記活物質はリチウム含有遷移金属酸化物であり、前記結着剤はフッ素を含む高分子材料であることを特徴とする請求項1に記載されている非水電解質二次電池用電極板。
- 前記集電体は鉄を含有するアルミニウム合金箔であることを特徴とする請求項1又は2に記載されている非水電解質二次電池用極板。
- リチウム含有遷移金属酸化物である活物質とフッ素を含む高分子材料である結着剤とを含む活物質合剤層を、鉄を含有するアルミニウム合金箔である集電体上に形成する工程Aと、
前記活物質合剤層を加熱して当該活物質合剤層の表面温度を内部温度よりも高くする工程Bと
を含み、
前記工程Bの後において、前記活物質合剤層の表面のダイナミック硬度が4.5以上であり、且つ内部のダイナミック硬度の方が表面よりも0.8以上大きいことを特徴とする、非水電解質二次電池用電極板の製造方法。 - 前記工程Bは加熱されたロールに前記活物質合剤層を当接させて行うものである、請求項4に記載されている非水電解質二次電池用電極板の製造方法。
- 前記工程Bは加熱されたシートに前記活物質合剤層を当接させて行うものである、請求項4に記載されている非水電解質二次電池用電極板の製造方法。
- 前記請求項1から3のいずれか一つに記載された非水電解質二次電池用電極板を正極板としている、非水電解質二次電池。
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JP2010530793A JP5325227B2 (ja) | 2009-03-16 | 2009-12-17 | 非水電解質二次電池用電極板及びその製造方法、並びに非水電解質二次電池 |
US13/002,611 US20110111302A1 (en) | 2009-03-16 | 2009-12-17 | Electrode plate for nonaqueous electrolyte secondary battery, method for fabricating the same, and nonaqueous electrolyte secondary battery |
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DE102012005426A1 (de) | 2012-03-16 | 2013-09-19 | Li-Tec Battery Gmbh | Graphen in Lithiumionen-Batterien |
JP6452609B2 (ja) | 2012-10-23 | 2019-01-16 | ビーエーエスエフ ソシエタス・ヨーロピアBasf Se | 正極を製造する方法 |
US9899682B2 (en) | 2013-07-30 | 2018-02-20 | Lg Chem, Ltd. | Electrode including coating layer for preventing reaction with electrolyte solution |
KR102022582B1 (ko) * | 2015-09-21 | 2019-09-18 | 주식회사 엘지화학 | 안전성이 향상된 전극 및 이를 포함하는 이차전지 |
DE102016220048A1 (de) | 2016-10-14 | 2018-04-19 | Bayerische Motoren Werke Aktiengesellschaft | Verwendung von graphen in einer lithiumionen-batterie |
CN109755462B (zh) * | 2017-11-08 | 2021-01-12 | 宁德时代新能源科技股份有限公司 | 一种正极极片、电化学装置及安全涂层 |
CN111837270A (zh) * | 2018-03-15 | 2020-10-27 | 松下知识产权经营株式会社 | 非水电解质二次电池及其制造方法 |
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