WO2018230058A1 - Secondary battery - Google Patents
Secondary battery Download PDFInfo
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- WO2018230058A1 WO2018230058A1 PCT/JP2018/009663 JP2018009663W WO2018230058A1 WO 2018230058 A1 WO2018230058 A1 WO 2018230058A1 JP 2018009663 W JP2018009663 W JP 2018009663W WO 2018230058 A1 WO2018230058 A1 WO 2018230058A1
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- WIPO (PCT)
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- positive electrode
- negative electrode
- secondary battery
- battery
- electrode mixture
- Prior art date
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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
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/50—Current conducting connections for cells or batteries
- H01M50/572—Means for preventing undesired use or discharge
- H01M50/574—Devices or arrangements for the interruption of current
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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
- 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
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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
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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
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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
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/30—Arrangements for facilitating escape of gases
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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 secondary battery used as a power source for an electric vehicle or a hybrid vehicle, for example.
- lithium ion secondary batteries have been used as power sources for electric vehicles and hybrid vehicles.
- a lithium ion secondary battery for automobiles is required to have high output, high energy density, and high safety.
- lithium ion secondary batteries it is important to ensure that the safety of the battery system is not compromised even during overcharging due to misoperation. In order to improve safety during overcharge, it is required to appropriately control the current interruption mechanism and heat generation of the secondary battery.
- lithium carbonate is used as a compound that generates a decomposition gas during overcharge and activates a current interruption mechanism, and numerically limits the lithium carbonate content in a specific positive electrode mixture.
- the present invention aims to solve the above problems. Specifically, it is to provide a secondary battery that can improve safety against overcharge.
- the secondary battery according to the present invention includes a positive electrode coated with a positive electrode mixture, a negative electrode coated with a negative electrode mixture, and a battery containing the positive electrode and the negative electrode.
- a secondary battery having a container and a current interrupting mechanism that interrupts current when the internal pressure of the battery container reaches a predetermined operating pressure, wherein the positive electrode mixture contains 1 wt% or more and 4 wt% or less.
- NP ratio which is the ratio of the capacity of the positive electrode to the capacity of the negative electrode, is 1.4 or more and 2.0 or less
- the coating amount of the positive electrode mixture is 110 g / m 2 or more. 140 g / m 2 or less.
- the NP ratio is preferably 1.4 or more and 1.6 or less, and the coating amount of the positive electrode mixture is preferably 120 g / m 2 or more and 140 g / m 2 or less. Moreover, NP ratio is 1.5, it is preferable coating amount of the positive electrode mixture is 130 g / m 2 or more 140 g / m 2 or less. Moreover, it is preferable that the coating amount of a positive mix is 130 g / m ⁇ 2 >.
- FIG. 2 is an exploded perspective view of the cylindrical secondary battery shown in FIG. 1.
- disconnected a part for showing the detail of the electrode group of FIG. 1 is an external perspective view of a prismatic secondary battery as one embodiment of the present invention.
- FIG. 5 is an exploded perspective view of the prismatic secondary battery shown in FIG. 4.
- surface which shows the structure of positive electrode mixture coating amount and NP ratio.
- FIG. 1 is a longitudinal sectional view showing an embodiment of a cylindrical secondary battery of the present invention.
- the cylindrical secondary battery 1 has dimensions of, for example, an outer diameter of 40 mm ⁇ and a height of 100 mm.
- the cylindrical secondary battery 1 is configured by housing the power generation unit 20 in a bottomed cylindrical battery can 60 whose opening is sealed with a sealing lid 50. First, the battery can 60 and the power generation unit 20 will be described, and then the sealing lid 50 will be described.
- a caulking portion 61 is formed at a can opening end portion (upper side in the figure).
- the caulking portion 61 includes an annular protrusion, a bent portion 62 formed by bending the end portion of the can opening inward, and a grooving portion 63 protruding inward at a predetermined distance from the battery bottom surface.
- the sealing lid 50 is caulked and fixed with the gasket 43 interposed between the bent portion 62 and the grooving portion 63, and the battery is sealed.
- the power generation unit 20 is configured by integrally uniting the electrode group 10, the positive electrode current collecting member 31, and the negative electrode current collecting member 21 as described below.
- the electrode group 10 has a shaft core 15 at the center, and a positive electrode, a negative electrode, and a separator are wound around the shaft core 15.
- a hollow cylindrical shaft core 15 is formed with a large-diameter recess 15a on the inner surface of the upper end in the axial direction (vertical direction in the drawing), and the positive electrode current collector 31 is press-fitted into the recess 15a.
- the positive electrode current collecting member 31 is formed of, for example, aluminum, and has a disk-like base portion 31a, a lower cylindrical portion 31b that protrudes toward the shaft core 15 side at the inner peripheral portion of the base portion 31a and is press-fitted into the inner surface of the shaft core 15. And an upper cylindrical portion 31c protruding toward the sealing lid 50 at the outer peripheral edge.
- An opening 31d for releasing gas generated inside the battery is formed in the base 31a of the positive electrode current collecting member 31.
- All the positive leads 16 of the positive electrode sheet 11 a are welded to the upper cylindrical portion 31 c of the positive current collecting member 31.
- the positive electrode lead 16 is overlapped and bonded onto the upper cylindrical portion 31 c of the positive electrode current collecting member 31. Since each positive electrode lead 16 is very thin, a large current cannot be taken out by one. Therefore, a large number of positive leads 16 are formed at predetermined intervals over the entire length from the start to the end of winding around the shaft core 15.
- the positive electrode lead 16 of the positive electrode sheet 11a and the ring-shaped pressing member 32 are welded to the outer periphery of the upper cylindrical portion 31c of the positive electrode current collecting member 31.
- a number of the positive leads 16 are brought into close contact with the outer periphery of the upper cylindrical portion 31 c of the positive current collecting member 31, and the pressing member 32 is wound around the outer periphery of the positive lead 16 and temporarily fixed, and is welded in this state.
- the positive electrode current collecting member 31 Since the positive electrode current collecting member 31 is oxidized by the electrolytic solution, the reliability can be improved by forming it with aluminum. When the surface of aluminum is exposed by some processing, an aluminum oxide film is immediately formed on the surface, and this aluminum oxide film can prevent oxidation by the electrolytic solution. Moreover, by forming the positive electrode current collecting member 31 from aluminum, the positive electrode lead 16 of the positive electrode sheet 11a can be welded by ultrasonic welding, spot welding, or the like.
- a step portion 15b having a small outer diameter is formed on the outer periphery of the lower end portion of the shaft core 15, and the negative electrode current collecting member 21 is press-fitted and fixed to the step portion 15b.
- the negative electrode current collecting member 21 is formed of, for example, copper, and an opening 21b that is press-fitted into the step portion 15b of the shaft core 15 is formed in a disc-shaped base portion 21a. An outer peripheral cylindrical portion 21c that protrudes out is formed.
- the negative electrode lead 17 of the negative electrode sheet 12a is all welded to the outer peripheral cylindrical portion 21c of the negative electrode current collecting member 21 by ultrasonic welding or the like. Since each negative electrode lead 17 is very thin, a large number of negative leads 17 are formed at predetermined intervals over the entire length from the start of winding to the shaft core 15 to take out a large current.
- the negative electrode lead 17 and the ring-shaped pressing member 22 of the negative electrode sheet 12a are welded to the outer periphery of the outer peripheral cylindrical portion 21c of the negative electrode current collecting member 21.
- a number of the negative electrode leads 17 are brought into close contact with the outer periphery of the outer peripheral cylindrical portion 21c of the negative electrode current collecting member 21, and the holding member 22 is wound around the outer periphery of the negative electrode lead 17 to be temporarily fixed, and are welded in this state.
- a negative electrode conducting lead 23 made of copper is welded to the lower surface of the negative electrode current collecting member 21.
- the negative electrode conducting lead 23 is welded to the battery can 60 at the bottom of the battery can 60.
- the battery can 60 is made of carbon steel having a thickness of 0.5 mm, for example, and has a nickel plating on the surface. By using such a material, the negative electrode conducting lead 23 can be welded to the battery can 60 by resistance welding or the like.
- a flexible positive electrode conductive lead 33 formed by laminating a plurality of aluminum foils is joined to the upper surface of the base portion 31a of the positive electrode current collecting member 31 by welding one end thereof.
- the positive electrode conductive lead 33 can flow a large current by laminating and integrating a plurality of aluminum foils, and is provided with flexibility. In other words, it is necessary to increase the thickness of the connecting member in order to pass a large current, but if it is formed of a single metal plate, the rigidity increases and the flexibility is impaired. Therefore, a large number of aluminum foils having a small thickness are laminated to give flexibility.
- the thickness of the positive electrode conductive lead 33 is, for example, about 0.5 mm, and is formed by stacking five aluminum foils having a thickness of 0.1 mm.
- FIG. 2 is an exploded perspective view of the cylindrical secondary battery shown in FIG.
- the electrode group 10 has a shaft core 15 at the center, and a positive electrode, a negative electrode, and a separator are wound around the shaft core 15. Then, the outermost first separator 13 is fixed with an adhesive tape 19.
- the sealing lid 50 includes a cap 3 having an exhaust port 3 c, a cap case 37 attached to the cap 3 and having a cleavage groove 37 a, a positive electrode connection plate 35 spot-welded to the back of the central portion of the cap case 37, and a positive electrode connection plate
- An insulating ring 41 sandwiched between the upper surface of the peripheral edge of 35 and the back surface of the cap case 37 is provided and assembled in advance as a subassembly.
- the cap 3 is formed by applying nickel plating to iron such as carbon steel.
- the cap 3 has a disc-shaped peripheral edge portion 3a and a headless and bottomless cylindrical portion 3b protruding upward from the peripheral edge portion 3a, and has a hat shape as a whole.
- An exhaust port 3c is formed at the center of the cylindrical portion 3b.
- the cylinder part 3b functions as a positive electrode external terminal and is connected to a bus bar or the like.
- the peripheral edge of the cap 3 is integrated with a folded flange 37b of a cap case 37 formed of an aluminum alloy.
- the cap 3 is caulked and fixed by folding the periphery of the cap case 37 along the upper surface of the cap 3.
- the ring that is folded back on the upper surface of the cap 3, that is, the flange 37 b and the cap 3 are friction-welded. That is, the cap case 37 and the cap 3 are integrated by caulking and welding by the flange 37b.
- the sealing lid 50 includes the flange 37b in which the cap case 37 and the cap 3 are integrated.
- a circular cleavage groove 37a and a cleavage groove 37a extending radially from the cleavage groove 37a are formed.
- the cleaving groove 37a is formed by crushing the upper surface side of the cap case 37 into a V shape by pressing and thinning the remaining portion.
- the cleavage groove 37a is cleaved when the internal pressure in the battery container 60 rises to a predetermined value or more, and releases the internal gas.
- the sealing lid 50 constitutes an explosion-proof mechanism.
- a crack occurs in the cap case 37 in the cleavage groove, and the internal gas is discharged from the exhaust port 3c of the cap 3 to be inside the battery can 60.
- the pressure of is reduced.
- the cap case 37 bulges outward from the container due to the internal pressure of the battery can 60, and the electrical connection with the positive electrode connection plate 35 is cut off, thereby suppressing overcurrent.
- the cylindrical secondary battery 1 is overcharged, and a positive electrode gas generating compound such as lithium carbonate contained in the positive electrode mixture is decomposed by the positive electrode potential to generate gas, and a battery can (battery container)
- a battery can battery container
- the internal pressure of 60 rises to a predetermined operating pressure, for example, a pressure in the range of 0.4 MPa or more and 1.0 MPa or less, the cap case 37 bulges outward from the container to interrupt the current (current) Blocking mechanism).
- the sealing lid 50 is placed on the upper cylindrical portion 31c of the positive electrode current collecting member 31 in an insulated state. That is, the cap case 37 in which the cap 3 is integrated is placed on the upper end surface of the positive electrode current collecting member 31 in an insulated state via the insulating ring 41. However, the cap case 37 is electrically connected to the positive electrode current collector 31 by the positive electrode conductive lead 33, and the cap 3 of the sealing lid 50 becomes the positive electrode of the cylindrical secondary battery 1.
- the insulating ring 41 has an opening 41a and a side portion 41b protruding downward. A connection plate 35 is fitted in the opening 41 a of the insulating ring 41.
- connection plate 35 is formed of an aluminum alloy, and has a substantially dish shape in which almost the whole except the central portion is uniform and the central side is bent to a slightly lower position.
- the thickness of the connection plate 35 is, for example, about 1 mm.
- a projection 35a that is thin and formed in a dome shape is formed at the center of the connection plate 35, and a plurality of openings 35b are formed around the projection 35a.
- the opening 35b has a function of releasing gas generated inside the battery.
- the protrusion 35a of the connection plate 35 is joined to the bottom surface of the central portion of the cap case 37 by resistance welding or friction diffusion bonding.
- the electrode group 10 is accommodated in the battery can 60, and the sealing lid 50 previously prepared as a partial assembly is electrically connected by the positive electrode current collecting member 31 and the positive electrode conductive lead 33 and placed on the upper part of the cylinder.
- the outer peripheral wall portion 43b of the gasket 43 is bent by pressing or the like, and the sealing lid 50 is crimped by the base portion 43a and the outer peripheral wall portion 43b so as to be pressed in the axial direction. Thereby, the sealing lid 50 is fixed to the battery can 60 via the gasket 43.
- the gasket 43 includes an outer peripheral wall portion 43b that is formed to stand substantially vertically toward the upper direction on the peripheral edge of the ring-shaped base portion 43a, and an inner peripheral side substantially downward from the base portion 43a. It has the shape which has the cylinder part 43c formed by dripping vertically.
- a predetermined amount of non-aqueous electrolyte is injected into the battery can 60.
- the non-aqueous electrolyte it is preferable to use a solution in which a lithium salt is dissolved in a carbonate solvent.
- the lithium salt include lithium fluorophosphate (LiPF 6 ), lithium fluoroborate (LiBF 6 ), and the like.
- carbonate solvents include ethylene carbonate (EC), dimethyl carbonate (DMC), propylene carbonate (PC), methyl ethyl carbonate (MEC), or a mixture of solvents selected from one or more of the above solvents, Is mentioned.
- FIG. 3 is a diagram for explaining the power generation unit, showing the details of the structure of the electrode group 10 and is a perspective view in a state where a part thereof is cut.
- the electrode group 10 has a configuration in which the positive electrode 11, the negative electrode 12, and the first and second separators 13 and 14 are wound around the outer periphery of the shaft core 15.
- the first separator 13 is wound on the innermost periphery that is in contact with the outer periphery of the shaft core 15, and the negative electrode 12, the second separator 14, and the positive electrode 11 are laminated in this order on the outer side. Has been wound up.
- a first separator 13 and a second separator 14 are wound several times inside the innermost negative electrode 12.
- the outermost periphery is the negative electrode 12 and the first separator 13 wound around the outer periphery.
- the positive electrode 11 is formed of an aluminum foil and has a strip shape.
- the positive electrode 11 includes a positive electrode sheet 11a and a positive electrode processing portion (positive electrode mixture layer) in which the positive electrode mixture 11b is applied to both surfaces of the positive electrode sheet 11a.
- the upper side edge along the longitudinal direction of the positive electrode sheet 11a is a positive electrode mixture untreated portion 11c where the positive electrode mixture 11b is not applied and the aluminum foil is exposed.
- a large number of positive electrode leads 16 protruding upward in parallel with the shaft core 15 are integrally formed at equal intervals.
- the positive electrode mixture 11b includes a positive electrode active material, a positive electrode conductive material, a positive electrode binder, and a positive electrode gas generating compound.
- the positive electrode active material is preferably lithium oxide. Examples include lithium cobaltate, lithium manganate, lithium nickelate, lithium composite oxide (lithium oxide containing two or more selected from cobalt, nickel, and manganese).
- the positive electrode conductive material is not limited as long as it can assist the transmission of electrons generated by the occlusion / release reaction of lithium in the positive electrode mixture to the positive electrode.
- Examples of the positive electrode conductive material include graphite and acetylene black.
- the positive electrode binder can bind the positive electrode active material and the positive electrode conductive material, and can bind the positive electrode mixture and the positive electrode current collector, and should not deteriorate significantly due to contact with the non-aqueous electrolyte.
- the positive electrode binder include polyvinylidene fluoride (PVDF) and fluororubber.
- an inorganic carbonate compound As the positive electrode gas generating compound, an inorganic carbonate compound, an oxalic acid inorganic compound, or a nitric acid inorganic compound that generates gas at a positive electrode potential in an overcharged state can be mentioned.
- a carbonic acid inorganic compound is preferable, for example, lithium carbonate.
- the content of lithium carbonate in the positive electrode mixture is preferably 1 wt% or more and 4 wt% or less, but in Example 1, it was 1.8 wt%.
- the method for forming the positive electrode mixture layer is not limited as long as the positive electrode mixture is formed on the positive electrode.
- a method for forming the positive electrode mixture 11b a method in which a dispersion solution of constituent materials of the positive electrode mixture 11b is applied on the positive electrode sheet 11a.
- Examples of the method for applying the positive electrode mixture 11b to the positive electrode sheet 11a include a roll coating method and a slit die coating method. After adding N-methylpyrrolidone (NMP) or water as an example of a solvent for the dispersion solution to the positive electrode mixture 11b and uniformly kneading the slurry on both sides of an aluminum foil having a thickness of 20 ⁇ m, and drying it. , Press and cut. An example of the coating thickness of the positive electrode mixture 11b is about 40 ⁇ m on one side. When cutting the positive electrode sheet 11a, the positive electrode lead 16 is integrally formed. In Example 1, the coating amount of the positive electrode mixture on one surface of the positive electrode is 140 g / m 2 .
- the negative electrode 12 is formed of a copper foil and has a strip shape.
- the negative electrode 12 includes a negative electrode sheet 12a and a negative electrode treatment portion (negative electrode mixture layer) in which a negative electrode mixture 12b is applied to both surfaces of the negative electrode sheet 12a.
- the lower side edge along the longitudinal direction of the negative electrode sheet 12a is a negative electrode mixture untreated portion 12c in which the negative electrode mixture 12b is not applied and the copper foil is exposed.
- a large number of negative electrode leads 17 extending in the direction opposite to the positive electrode lead 16 are integrally formed at equal intervals.
- the negative electrode mixture 12b is composed of a negative electrode active material, a negative electrode binder, and a thickener.
- the negative electrode mixture 12b may have a negative electrode conductive material such as acetylene black.
- Graphite carbon is preferably used as the negative electrode active material. By using graphite carbon, a lithium ion secondary battery for a plug-in hybrid vehicle or an electric vehicle requiring a large capacity can be manufactured.
- the formation method of the negative electrode mixture 12b is not limited as long as the negative electrode mixture 12b is formed on the negative electrode sheet 12a.
- a method of applying the negative electrode mixture 12b to the negative electrode sheet 12a a method of applying a dispersion solution of the constituent material of the negative electrode mixture 12b onto the negative electrode sheet 12a can be mentioned.
- the coating method include a roll coating method and a slit die coating method.
- N-methyl-2-pyrrolidone or water as a dispersion solvent is added to the negative electrode mixture 12b, and the kneaded slurry is rolled into a 10 ⁇ m thick rolled copper foil. After coating uniformly on both sides, press and cut.
- An example of the coating thickness of the negative electrode mixture 12b is about 40 ⁇ m on one side.
- the width of the first separator 13 and the second separator 14 is W S
- the width of the negative electrode mixture 12b formed on the negative electrode sheet 12a is W C
- the width of the positive electrode mixture 11b formed on the positive electrode sheet 11a is W A. In this case, it is formed so as to satisfy the following formula. W S > W C > W A
- the width W C of the negative electrode mixture 12b is always larger than the width W A of the positive electrode mixture 11b. This is because in the case of a lithium ion secondary battery, lithium as the positive electrode active material is ionized and penetrates the separator, but the negative electrode sheet is not formed on the negative electrode side and the negative electrode sheet 12a is exposed. This is because lithium is deposited on 12a and causes an internal short circuit.
- the negative electrode capacity / positive electrode capacity which is the ratio of the respective capacities of the formed positive electrode and negative electrode, was defined as the NP ratio.
- the NP ratio is preferably 1.1 or more, but in Example 1, it was set to 1.4.
- Example 1 As described above, in the secondary battery of Example 1, the lithium carbonate content in the positive electrode mixture was 1.8 wt%, the NP ratio was 1.4, and the coating amount of the positive electrode mixture on one surface of the positive electrode was 140 g / m 2 .
- Example 2 A secondary battery of Example 2 was produced in the same manner as in Example 1 except that the coating amount of the positive electrode mixture was 130 g / m 2 .
- Example 3 A secondary battery of Example 3 was produced in the same manner as in Example 1 except that the coating amount of the positive electrode mixture was 120 g / m 2 .
- Example 4 A secondary battery of Example 4 was produced in the same manner as in Example 1, except that the coating amount of the positive electrode mixture was 110 g / m 2 .
- Example 5 A secondary battery of Example 5 was made in the same manner as in Example 1 except that NP was made to be 1.5.
- Comparative Example 1 A secondary battery of Comparative Example 1 was fabricated in the same manner as in Example 1 except that the coating amount of the positive electrode mixture was 110 g / m 2 and the NP ratio was 1.1.
- Comparative Example 2 A secondary battery of Comparative Example 2 was fabricated in the same manner as in Example 1 except that the coating amount of the positive electrode mixture was 110 g / m 2 and the NP ratio was 1.2.
- Comparative Example 3 A secondary battery of Comparative Example 2 was fabricated in the same manner as in Example 1 except that the coating amount of the positive electrode mixture was 90 g / m 2 and the NP ratio was 1.2.
- Comparative Example 4 A secondary battery of Comparative Example 2 was produced in the same manner as in Example 1 except that the NP ratio was made to be 1.3.
- Comparative Example 5 A secondary battery of Comparative Example 5 was fabricated in the same manner as in Example 1 except that the coating amount of the positive electrode mixture was 130 g / m 2 and the NP ratio was 1.3.
- Comparative Example 6 A secondary battery of Comparative Example 6 was fabricated in the same manner as in Example 1 except that the coating amount of the positive electrode mixture was 120 g / m 2 and the NP ratio was 1.3.
- FIG. 4 is an external perspective view of a prismatic secondary battery 100 as an embodiment of the electricity storage device
- FIG. 5 is an exploded perspective view showing the configuration of the prismatic secondary battery 100.
- the square secondary battery 100 includes a battery container including a battery can 101 and a battery lid 102.
- the material of the battery can 101 and the battery lid 102 is aluminum or an aluminum alloy.
- the battery can 101 is formed in a flat rectangular box shape with one end opened by performing deep drawing.
- the battery can 101 includes a rectangular plate-like bottom plate 101c, a pair of wide side plates 101a rising from each of a pair of long sides of the bottom plate 101c, and a pair of narrow side plates 101b rising from each of a pair of short sides of the bottom plate 101c. And have.
- the battery can 101 accommodates a wound electrode group 170 (see FIG. 6).
- the positive electrode current collector 180 joined to the positive electrode 174 of the wound electrode group 170 and the negative electrode 175 of the wound electrode group 170 are joined.
- the negative electrode current collector 190 and the wound electrode group 170 are composed of an insulating sheet 108a covering the center of the wound electrode group, an insulating sheet 108b covering the positive electrode uncoated part of the wound electrode group, and a negative electrode uncoated of the wound electrode group. It is accommodated in the battery can 101 in a state covered with an insulating sheet 108c covering the construction part.
- the material of the insulating sheets 108a, 108b, 108c is an insulating resin such as polypropylene, and the battery can 101 and the wound electrode group 170 are electrically insulated.
- the battery lid 102 has a rectangular flat plate shape and is laser-welded so as to close the opening of the battery can 101. That is, the battery lid 102 seals the opening of the battery can 101.
- a positive electrode external terminal 104 and a negative electrode external terminal 105 that are electrically connected to the positive electrode 174 and the negative electrode 175 of the wound electrode group 170 are disposed on the battery lid 102.
- the positive external terminal 104 is electrically connected to the positive electrode 174 (see FIG. 3) of the wound electrode group 170 via the current interrupt mechanism 181 and the positive current collector 180, and the negative external terminal 105. Is electrically connected to the negative electrode 175 of the wound electrode group 170 via the negative electrode current collector 190. Therefore, electric power is supplied to the external device via the positive external terminal 104 and the negative external terminal 105, or external generated power is supplied to the wound electrode group 170 via the positive external terminal 104 and the negative external terminal 105. Charged.
- the battery lid 102 is provided with a liquid injection hole 106 a for injecting an electrolytic solution into the battery container.
- the liquid injection hole 106a is sealed by a liquid injection plug 106b after the electrolytic solution is injected.
- the electrolytic solution for example, a non-aqueous electrolytic solution in which a lithium salt such as lithium hexafluorophosphate (LiPF 6 ) is dissolved in a carbonate-based organic solvent such as ethylene carbonate can be used.
- the battery cover 102 is provided with a gas discharge valve 103.
- the gas discharge valve 103 is formed by partially thinning the battery lid 102 by press working.
- the thin-walled member may be attached to the opening of the battery lid 102 by laser welding or the like, and the thin portion may be used as a gas discharge valve.
- the gas discharge valve 103 is heated when the rectangular secondary battery 100 generates heat due to an abnormality such as an internal short circuit, and gas is generated. By discharging, the pressure in the battery container is reduced.
- the current interruption mechanism 181 operates when the square secondary battery 100 is overcharged, the positive electrode gas generating compound is decomposed by the positive electrode potential at that time, gas is generated, and the internal pressure is increased.
- the current interruption mechanism 181 has, for example, a diaphragm, and when the inside of the battery container reaches a predetermined operating pressure, for example, a pressure in a range of 0.4 MPa to 1.0 MPa, the diaphragm is deformed to interrupt the contact. It has a configuration.
- the wound electrode group 170 will be described with reference to FIG. FIG. 6 is a perspective view showing the wound electrode group 170 and shows a state where the winding end side of the wound electrode group 170 is developed.
- the wound electrode group 170 which is a power generation element, has a laminated structure by winding a belt-like positive electrode 174 and a negative electrode 175 in a flat shape around the wound central axis W with separators 173a and 173b interposed. .
- the positive electrode 174 has a positive electrode mixture layer 176 formed on both surfaces of the positive electrode foil 171.
- the positive electrode mixture is a mixture of a positive electrode active material and a binder (binder) and a positive gas generating compound.
- the positive electrode gas generating compound include a carbonic acid inorganic compound, an oxalic acid inorganic compound, or a nitric acid inorganic compound that generates gas at a positive electrode potential in an overcharged state.
- a carbonic acid inorganic compound is preferable, for example, lithium carbonate.
- the negative electrode 175 has a negative electrode mixture layer 177 formed on both surfaces of a negative electrode foil 172.
- the negative electrode mixture is a mixture of a negative electrode active material and a binder.
- the positive foil 171 is an aluminum foil having a thickness of about 20 to 30 ⁇ m
- the negative foil 172 is a copper foil having a thickness of about 15 to 20 ⁇ m.
- the material of the separators 173a and 173b is a microporous polyethylene resin through which lithium ions can pass.
- the positive electrode active material is a lithium-containing transition metal double oxide such as lithium manganate
- the negative electrode active material is a carbon material such as graphite capable of reversibly occluding and releasing lithium ions.
- One of the end portions of the winding electrode group 170 in the width direction, that is, the direction of the winding central axis W perpendicular to the winding direction is a laminated portion of the positive electrode 174 and the other is a laminated portion of the negative electrode 175.
- the laminated portion of the positive electrode 174 provided at one end is obtained by laminating an uncoated positive electrode portion where the positive electrode mixture layer 176 is not formed, that is, an exposed portion of the positive foil 171.
- the laminated portion of the negative electrode 175 provided at the other end is obtained by laminating the negative electrode uncoated portion where the negative electrode mixture layer 177 is not formed, that is, the exposed portion of the negative electrode foil 172.
- the laminated portion of the positive electrode uncoated portion and the laminated portion of the negative electrode uncoated portion are respectively crushed in advance and connected to the positive electrode current collector 180 and the negative electrode current collector 190 by ultrasonic bonding, respectively.
- FIG. 7 is a table showing the composition of the coating amount and the NP ratio of the positive electrode mixture of the cylindrical secondary batteries of Examples 1 to 5 and Comparative Examples 1 to 6.
- the lithium carbonate content is 1.8 wt% (wt%).
- FIG. 8 is a table showing test results of overcharge tests of Examples 1 to 5 and Comparative Examples 1 to 6. All the batteries were put into the end-of-charge state by constant current and constant voltage charging for 10 hours, 10 A, 4.2 V, and 3 hours before the test. At a temperature of 25 ° C., a direct current of 8.4 V and 10 A was applied to each battery using a direct current power source capable of knowing the accumulated amount of electricity supplied. The test was terminated when the current interruption mechanism was activated and the battery temperature was around 20 ° C.
- the overcharge test results shown in FIG. 8 are the battery heat generation maximum temperature (° C.), the current interruption mechanism operation SOC (%), and the overcharge capacity (Ah) during the test.
- the boundary line of the coating amount 110 g / m 2 of the positive electrode mixture in the range of claim 1 is a boundary where the absolute amount of lithium carbonate in the battery is not less than the content of the coating amount 110 g / m 2 of the positive electrode mixture.
- the boundary line of NP ratio 1.4 is a boundary with high safety
- the boundary line of the coating amount of the positive electrode mixture of 140 g / m 2 is the result of the NP ratio of 1.4 or more, the overcharge capacity of 14 Ah or less, and the maximum battery heat generation temperature of 120 ° C. or less. Is set because a high boundary was confirmed.
- the boundary of the NP ratio 2.0 is set because an internal resistance increase of 1.3 times or more is expected compared to the NP ratio 1.4, and battery heat generation is expected to become remarkable.
- the range of claim 2 shows the range where safety improvement at the time of overcharge can be expected with respect to claim 1.
- the range of claim 3 shows the range in which the safety improvement at the time of overcharge can be expected with respect to claim 2.
- Claim 4 has shown the structure of the coating amount and NP ratio of the positive mix which can anticipate the safety
- the present invention is not limited to the above-described embodiments, and various designs can be made without departing from the spirit of the present invention described in the claims. It can be changed.
- the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described.
- a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment.
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Abstract
The present invention addresses the problem of providing a secondary battery which has improved safety against overcharging. A secondary battery according to the present invention is a cylindrical secondary battery (1) that comprises a positive electrode (174), a negative electrode (175) and a current interrupting mechanism (181), said cylindrical secondary battery (1) being characterized in that: the positive electrode mixture contains from 1% by weight to 4% by weight (inclusive) of lithium carbonate; the NP ratio, which is the ratio of the negative electrode capacity to the positive electrode capacity, is from 1.4 to 2.0 (inclusive); and the coating amount of the positive electrode mixture is from 110 g/m2 to 140 g/m2 (inclusive).
Description
本発明は、例えば電気自動車やハイブリッド自動車の電源として用いられる二次電池に関するものである。
The present invention relates to a secondary battery used as a power source for an electric vehicle or a hybrid vehicle, for example.
近年、リチウムイオン二次電池は、電気自動車及びハイブリッド自動車の電源として用いられている。自動車用のリチウムイオン二次電池は、高出力、高エネルギー密度および高安全性が求められている。
In recent years, lithium ion secondary batteries have been used as power sources for electric vehicles and hybrid vehicles. A lithium ion secondary battery for automobiles is required to have high output, high energy density, and high safety.
また、リチウムイオン二次電池では、誤操作における過充電時でも電池システムの安全性が損なわれないようにすることが重要である。過充電時の安全性を向上させるために、二次電池の電流遮断機構や発熱を適切に制御することが求められている。
Also, with lithium ion secondary batteries, it is important to ensure that the safety of the battery system is not compromised even during overcharging due to misoperation. In order to improve safety during overcharge, it is required to appropriately control the current interruption mechanism and heat generation of the secondary battery.
特許文献1には、過充電時に分解ガスを発生して電流遮断機構を作動させる化合物として炭酸リチウムを用い、具体的な正極合剤中に占める炭酸リチウムの含有量を数値限定している。
In Patent Document 1, lithium carbonate is used as a compound that generates a decomposition gas during overcharge and activates a current interruption mechanism, and numerically limits the lithium carbonate content in a specific positive electrode mixture.
しかしながら、特許文献1の方法では、炭酸リチウムの含有量を増加させることができない場合に、二次電池の正極電極と負極電極の構成内容を変更して、過充電に対しての安全性を向上させることはできない。
However, in the method of Patent Document 1, when the content of lithium carbonate cannot be increased, the configuration content of the positive electrode and the negative electrode of the secondary battery is changed to improve safety against overcharging. I can't let you.
本発明は上記課題を解決することを目的とする。具体的には、過充電に対して安全性を向上させることができる二次電池を提供することである。
The present invention aims to solve the above problems. Specifically, it is to provide a secondary battery that can improve safety against overcharge.
上記課題を解決するために本発明における二次電池は、正極合剤が塗工された正極電極と、負極合剤が塗工された負極電極と、前記正極電極と前記負極電極を収容する電池容器と、該電池容器の内圧が所定の作動圧となったときに電流を遮断する電流遮断機構と、を有する二次電池であって、前記正極合剤には1重量%以上4重量%以下の炭酸リチウムを含み、前記正極電極の容量と前記負極電極の容量との比であるNP比が1.4以上2.0以下であり、前記正極合剤の塗工量が110g/m2以上140g/m2以下であることを特徴とする。
In order to solve the above problems, the secondary battery according to the present invention includes a positive electrode coated with a positive electrode mixture, a negative electrode coated with a negative electrode mixture, and a battery containing the positive electrode and the negative electrode. A secondary battery having a container and a current interrupting mechanism that interrupts current when the internal pressure of the battery container reaches a predetermined operating pressure, wherein the positive electrode mixture contains 1 wt% or more and 4 wt% or less. NP ratio, which is the ratio of the capacity of the positive electrode to the capacity of the negative electrode, is 1.4 or more and 2.0 or less, and the coating amount of the positive electrode mixture is 110 g / m 2 or more. 140 g / m 2 or less.
また、NP比が1.4以上1.6以下であり、正極合剤の塗工量が120g/m2以上140g/m2以下であることが好ましい。また、NP比が1.5であり、正極合剤の塗工量が130g/m2以上140g/m2以下であることが好ましい。また、正極合剤の塗工量が130g/m2であることが好ましい。
The NP ratio is preferably 1.4 or more and 1.6 or less, and the coating amount of the positive electrode mixture is preferably 120 g / m 2 or more and 140 g / m 2 or less. Moreover, NP ratio is 1.5, it is preferable coating amount of the positive electrode mixture is 130 g / m 2 or more 140 g / m 2 or less. Moreover, it is preferable that the coating amount of a positive mix is 130 g / m < 2 >.
本発明によれば、過充電に対する安全性に優れた二次電池を提供することができる。
本発明に関連する更なる特徴は、本明細書の記述、添付図面から明らかになるものである。また、上記した以外の、課題、構成及び効果は、以下の実施形態の説明により明らかにされる。 ADVANTAGE OF THE INVENTION According to this invention, the secondary battery excellent in the safety | security with respect to an overcharge can be provided.
Further features related to the present invention will become apparent from the description of the present specification and the accompanying drawings. Further, problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.
本発明に関連する更なる特徴は、本明細書の記述、添付図面から明らかになるものである。また、上記した以外の、課題、構成及び効果は、以下の実施形態の説明により明らかにされる。 ADVANTAGE OF THE INVENTION According to this invention, the secondary battery excellent in the safety | security with respect to an overcharge can be provided.
Further features related to the present invention will become apparent from the description of the present specification and the accompanying drawings. Further, problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.
図1は、この発明の円筒形二次電池の実施形態を示す縦断面図である。円筒形二次電池1は、例えば、外形40mmφ、高さ100mmの寸法を有する。この円筒形二次電池1は、密閉蓋50で開口部が封止される有底円筒形の電池缶60の内部に発電ユニット20を収容して構成されている。まず、電池缶60と発電ユニット20について説明し、次に、密閉蓋50を説明する。
FIG. 1 is a longitudinal sectional view showing an embodiment of a cylindrical secondary battery of the present invention. The cylindrical secondary battery 1 has dimensions of, for example, an outer diameter of 40 mmφ and a height of 100 mm. The cylindrical secondary battery 1 is configured by housing the power generation unit 20 in a bottomed cylindrical battery can 60 whose opening is sealed with a sealing lid 50. First, the battery can 60 and the power generation unit 20 will be described, and then the sealing lid 50 will be described.
有底円筒形の電池缶60には、缶開口端部 (図中上側)にかしめ部61が形成されている。このかしめ部61で密閉蓋50を電池缶60にかしめ固定することにより、開口部を密閉し、非水電解液を使用する密閉形の円筒形二次電池1のシール性能を担保している。かしめ部61は、環状突部、缶開口端部を内側に折り曲げてなる折り曲げ部62、および電池底面側に所定距離離れた位置で内側に突き出したグルービング部63を備えている。後述するように、折り曲げ部62とグルービング部63との間にガスケット43を介在させて密閉蓋50がかしめ固定され、電池が密閉されている。
In the bottomed cylindrical battery can 60, a caulking portion 61 is formed at a can opening end portion (upper side in the figure). By caulking and fixing the sealing lid 50 to the battery can 60 with the caulking portion 61, the opening portion is hermetically sealed and the sealing performance of the sealed cylindrical secondary battery 1 using a non-aqueous electrolyte is ensured. The caulking portion 61 includes an annular protrusion, a bent portion 62 formed by bending the end portion of the can opening inward, and a grooving portion 63 protruding inward at a predetermined distance from the battery bottom surface. As will be described later, the sealing lid 50 is caulked and fixed with the gasket 43 interposed between the bent portion 62 and the grooving portion 63, and the battery is sealed.
発電ユニット20は、電極群10と、正極集電部材31と、負極集電部材21とを、以下で説明するように一体的にユニット化して構成されている。電極群10は、中央部に軸芯15を有し、軸芯15の周囲に正極電極、負極電極およびセパレータが捲回されている。中空な円筒形状の軸芯15は軸方向(図面の上下方向)の上端部の内面に径大の凹部15aが形成され、この凹部15aに正極集電部材31が圧入されている。正極集電部材31は、例えば、アルミニウムにより形成され、円盤状の基部31a、この基部31aの内周部において軸芯15側に向かって突出し、軸芯15の内面に圧入される下部筒部31b、および外周縁において密閉蓋50側に突き出す上部筒部31cを有する。正極集電部材31の基部31aには、電池内部で発生するガスを放出するための開口部31dが形成されている。
The power generation unit 20 is configured by integrally uniting the electrode group 10, the positive electrode current collecting member 31, and the negative electrode current collecting member 21 as described below. The electrode group 10 has a shaft core 15 at the center, and a positive electrode, a negative electrode, and a separator are wound around the shaft core 15. A hollow cylindrical shaft core 15 is formed with a large-diameter recess 15a on the inner surface of the upper end in the axial direction (vertical direction in the drawing), and the positive electrode current collector 31 is press-fitted into the recess 15a. The positive electrode current collecting member 31 is formed of, for example, aluminum, and has a disk-like base portion 31a, a lower cylindrical portion 31b that protrudes toward the shaft core 15 side at the inner peripheral portion of the base portion 31a and is press-fitted into the inner surface of the shaft core 15. And an upper cylindrical portion 31c protruding toward the sealing lid 50 at the outer peripheral edge. An opening 31d for releasing gas generated inside the battery is formed in the base 31a of the positive electrode current collecting member 31.
正極シート11aの正極リード16は、すべて、正極集電部材31の上部筒部31cに溶接される。この場合、正極リード16は、正極集電部材31の上部筒部31c上に重なり合って接合される。各正極リード16は大変薄いため、1つでは大電流を取りだすことができない。このため、軸芯15への巻き始めから巻き終わりまでの全長に亘り、多数の正極リード16が所定間隔に形成されている。
All the positive leads 16 of the positive electrode sheet 11 a are welded to the upper cylindrical portion 31 c of the positive current collecting member 31. In this case, the positive electrode lead 16 is overlapped and bonded onto the upper cylindrical portion 31 c of the positive electrode current collecting member 31. Since each positive electrode lead 16 is very thin, a large current cannot be taken out by one. Therefore, a large number of positive leads 16 are formed at predetermined intervals over the entire length from the start to the end of winding around the shaft core 15.
正極集電部材31の上部筒部31cの外周には、正極シート11aの正極リード16およびリング状の押え部材32が溶接されている。多数の正極リード16は、正極集電部材31の上部筒部31cの外周に密着させておき、正極リード16の外周に押え部材32を巻き付けて仮固定し、この状態で溶接される。
The positive electrode lead 16 of the positive electrode sheet 11a and the ring-shaped pressing member 32 are welded to the outer periphery of the upper cylindrical portion 31c of the positive electrode current collecting member 31. A number of the positive leads 16 are brought into close contact with the outer periphery of the upper cylindrical portion 31 c of the positive current collecting member 31, and the pressing member 32 is wound around the outer periphery of the positive lead 16 and temporarily fixed, and is welded in this state.
正極集電部材31は、電解液によって酸化されるので、アルミニウムで形成することにより信頼性を向上することができる。アルミニウムは、なんらかの加工により表面が露出すると、直ちに、表面に酸化アルミニウム皮膜が形成され、この酸化アルミニウム皮膜により、電解液による酸化を防止することができる。また、正極集電部材31をアルミニウムで形成することにより、正極シート11aの正極リード16を超音波溶接またはスポット溶接等により溶接することが可能となる。
Since the positive electrode current collecting member 31 is oxidized by the electrolytic solution, the reliability can be improved by forming it with aluminum. When the surface of aluminum is exposed by some processing, an aluminum oxide film is immediately formed on the surface, and this aluminum oxide film can prevent oxidation by the electrolytic solution. Moreover, by forming the positive electrode current collecting member 31 from aluminum, the positive electrode lead 16 of the positive electrode sheet 11a can be welded by ultrasonic welding, spot welding, or the like.
軸芯15の下端部の外周には、外径が径小とされた段部15bが形成され、この段部15bに負極集電部材21が圧入されて固定されている。負極集電部材21は、例えば、銅により形成され、円盤状の基部21aに軸芯15の段部15bに圧入される開口部21bが形成され、外周縁に、電池容器60の底部側に向かって突き出す外周筒部21cが形成されている。
A step portion 15b having a small outer diameter is formed on the outer periphery of the lower end portion of the shaft core 15, and the negative electrode current collecting member 21 is press-fitted and fixed to the step portion 15b. The negative electrode current collecting member 21 is formed of, for example, copper, and an opening 21b that is press-fitted into the step portion 15b of the shaft core 15 is formed in a disc-shaped base portion 21a. An outer peripheral cylindrical portion 21c that protrudes out is formed.
負極シート12aの負極リード17は、すべて、負極集電部材21の外周筒部21cに超音波溶接等により溶接される。各負極リード17は大変薄いため、大電流を取りだすために、軸芯15への巻き始めから巻き終わりまで全長にわたり、所定間隔で多数形成されている。
The negative electrode lead 17 of the negative electrode sheet 12a is all welded to the outer peripheral cylindrical portion 21c of the negative electrode current collecting member 21 by ultrasonic welding or the like. Since each negative electrode lead 17 is very thin, a large number of negative leads 17 are formed at predetermined intervals over the entire length from the start of winding to the shaft core 15 to take out a large current.
負極集電部材21の外周筒部21cの外周には、負極シート12aの負極リード17およびリング状の押え部材22が溶接されている。多数の負極リード17は、負極集電部材21の外周筒部21cの外周に密着させておき、負極リード17の外周に押え部材22を巻き付けて仮固定し、この状態で溶接される。
The negative electrode lead 17 and the ring-shaped pressing member 22 of the negative electrode sheet 12a are welded to the outer periphery of the outer peripheral cylindrical portion 21c of the negative electrode current collecting member 21. A number of the negative electrode leads 17 are brought into close contact with the outer periphery of the outer peripheral cylindrical portion 21c of the negative electrode current collecting member 21, and the holding member 22 is wound around the outer periphery of the negative electrode lead 17 to be temporarily fixed, and are welded in this state.
負極集電部材21の下面には、銅製の負極通電リード23が溶接されている。負極通電リード23は、電池缶60の底部において、電池缶60に溶接されている。電池缶60は、例えば、0.5mmの厚さの炭素鋼で形成され、表面にニッケルメッキが施されている。このような材料を用いることにより、負極通電リード23は、電池缶60に抵抗溶接等により溶接することができる。
A negative electrode conducting lead 23 made of copper is welded to the lower surface of the negative electrode current collecting member 21. The negative electrode conducting lead 23 is welded to the battery can 60 at the bottom of the battery can 60. The battery can 60 is made of carbon steel having a thickness of 0.5 mm, for example, and has a nickel plating on the surface. By using such a material, the negative electrode conducting lead 23 can be welded to the battery can 60 by resistance welding or the like.
正極集電部材31の基部31aの上面には、複数のアルミニウム箔が積層されて構成されたフレキシブルな正極導電リード33が、その一端部を溶接されて接合されている。正極導電リード33は、複数枚のアルミニウム箔を積層して一体化することにより、大電流を流すことが可能とされ、且つ、フレキシブル性を付与されている。つまり、大電流を流すには接続部材の厚さを大きくする必要があるが、1枚の金属板で形成すると剛性が大きくなり、フレキシブル性が損なわれる。そこで、板厚の小さな多数のアルミニウム箔を積層してフレキシブル性を持たせている。正極導電リード33の厚さは、例えば、0.5mm程度であり、厚さ0.1mmのアルミニウム箔を5枚積層して形成される。
A flexible positive electrode conductive lead 33 formed by laminating a plurality of aluminum foils is joined to the upper surface of the base portion 31a of the positive electrode current collecting member 31 by welding one end thereof. The positive electrode conductive lead 33 can flow a large current by laminating and integrating a plurality of aluminum foils, and is provided with flexibility. In other words, it is necessary to increase the thickness of the connecting member in order to pass a large current, but if it is formed of a single metal plate, the rigidity increases and the flexibility is impaired. Therefore, a large number of aluminum foils having a small thickness are laminated to give flexibility. The thickness of the positive electrode conductive lead 33 is, for example, about 0.5 mm, and is formed by stacking five aluminum foils having a thickness of 0.1 mm.
図2は、図1に示された円筒形二次電池の分解斜視図である。
電極群10は、中央部に軸芯15を有し、軸芯15の周囲に正極電極、負極電極およびセパレータが捲回されている。そして最外周の第1のセパレータ13が接着テープ19で止められる。 FIG. 2 is an exploded perspective view of the cylindrical secondary battery shown in FIG.
Theelectrode group 10 has a shaft core 15 at the center, and a positive electrode, a negative electrode, and a separator are wound around the shaft core 15. Then, the outermost first separator 13 is fixed with an adhesive tape 19.
電極群10は、中央部に軸芯15を有し、軸芯15の周囲に正極電極、負極電極およびセパレータが捲回されている。そして最外周の第1のセパレータ13が接着テープ19で止められる。 FIG. 2 is an exploded perspective view of the cylindrical secondary battery shown in FIG.
The
密閉蓋50は、排気口3cを有するキャップ3と、キャップ3に装着され開裂溝37aを有するキャップケース37と、キャップケース37の中央部裏面にスポット溶接された正極接続板35と、正極接続板35の周縁上面とキャップケース37の裏面との間に挟持される絶縁リング41とを備え、予めサブアセンブリとして組み立てられている。
The sealing lid 50 includes a cap 3 having an exhaust port 3 c, a cap case 37 attached to the cap 3 and having a cleavage groove 37 a, a positive electrode connection plate 35 spot-welded to the back of the central portion of the cap case 37, and a positive electrode connection plate An insulating ring 41 sandwiched between the upper surface of the peripheral edge of 35 and the back surface of the cap case 37 is provided and assembled in advance as a subassembly.
キャップ3は、炭素鋼等の鉄にニッケルメッキを施して形成されている。キャップ3は、円盤状の周縁部3aと、この周縁部3aから上方に突出する有頭無底の筒部3bとを有し、全体としてハット型を呈している。筒部3bには、中央に排気口3cが形成されている。筒部3bは正極外部端子として機能し、バスバーなどが接続される。
The cap 3 is formed by applying nickel plating to iron such as carbon steel. The cap 3 has a disc-shaped peripheral edge portion 3a and a headless and bottomless cylindrical portion 3b protruding upward from the peripheral edge portion 3a, and has a hat shape as a whole. An exhaust port 3c is formed at the center of the cylindrical portion 3b. The cylinder part 3b functions as a positive electrode external terminal and is connected to a bus bar or the like.
キャップ3の周縁部は、アルミニウム合金で形成されたキャップケース37の折り返しフランジ37bで一体化されている。すなわち、キャップケース37の周縁をキャップ3の上面に沿って折り返してキャップ3がかしめ固定されている。キャップ3の上面で折り返されている円環、すなわちフランジ37bとキャップ3が摩擦接合溶接されている。すなわち、キャップケース37とキャップ3は、フランジ37bによるかしめ固定と溶接によって一体化されている。このように、密閉蓋50はキャップケース37とキャップ3とが一体化したフランジ37bを備えている。
The peripheral edge of the cap 3 is integrated with a folded flange 37b of a cap case 37 formed of an aluminum alloy. In other words, the cap 3 is caulked and fixed by folding the periphery of the cap case 37 along the upper surface of the cap 3. The ring that is folded back on the upper surface of the cap 3, that is, the flange 37 b and the cap 3 are friction-welded. That is, the cap case 37 and the cap 3 are integrated by caulking and welding by the flange 37b. As described above, the sealing lid 50 includes the flange 37b in which the cap case 37 and the cap 3 are integrated.
キャップケース37の中央円形領域には、円形形状の開裂溝37aと、この開裂溝37aから四方に放射状に伸びる開裂溝37aとが形成されている。開裂溝37aは、プレスによりキャップケース37の上面側をV字形状に押し潰して、残部を薄肉にしたものである。開裂溝37aは、電池容器60内の内圧が所定値以上に上昇すると開裂して、内部のガスを放出する。
In the central circular region of the cap case 37, a circular cleavage groove 37a and a cleavage groove 37a extending radially from the cleavage groove 37a are formed. The cleaving groove 37a is formed by crushing the upper surface side of the cap case 37 into a V shape by pressing and thinning the remaining portion. The cleavage groove 37a is cleaved when the internal pressure in the battery container 60 rises to a predetermined value or more, and releases the internal gas.
密閉蓋50は防爆機構を構成している。電池缶60の内部に発生したガスにより、内部圧力が基準値を超えると、開裂溝においてキャップケース37に亀裂が発生し、内部のガスがキャップ3の排気口3cから排出されて電池缶60内の圧力が低減される。また、電池缶60の内圧によりキャップケース37が容器外方に膨出して正極接続板35との電気的接続が断たれ、過電流を抑制する。円筒形二次電池1は、過充電状態となり、正極合剤に含有されている炭酸リチウムなどの正極ガス発生化合物がそのときの正極電位により分解してガスが発生し、電池缶(電池容器)60の内圧が上昇して所定の作動圧、例えば0.4MPa以上1.0MPa以下の範囲の圧力となったときにキャップケース37が容器外方に膨出して電流を遮断する構成を有する(電流遮断機構)。
The sealing lid 50 constitutes an explosion-proof mechanism. When the internal pressure exceeds the reference value due to the gas generated in the battery can 60, a crack occurs in the cap case 37 in the cleavage groove, and the internal gas is discharged from the exhaust port 3c of the cap 3 to be inside the battery can 60. The pressure of is reduced. Further, the cap case 37 bulges outward from the container due to the internal pressure of the battery can 60, and the electrical connection with the positive electrode connection plate 35 is cut off, thereby suppressing overcurrent. The cylindrical secondary battery 1 is overcharged, and a positive electrode gas generating compound such as lithium carbonate contained in the positive electrode mixture is decomposed by the positive electrode potential to generate gas, and a battery can (battery container) When the internal pressure of 60 rises to a predetermined operating pressure, for example, a pressure in the range of 0.4 MPa or more and 1.0 MPa or less, the cap case 37 bulges outward from the container to interrupt the current (current) Blocking mechanism).
密閉蓋50は、正極集電部材31の上部筒部31c上に絶縁状態で載置されている。すなわち、キャップ3が一体化されたキャップケース37は、その絶縁リング41を介して絶縁状態で正極集電部材31の上端面に載置されている。しかし、キャップケース37は、正極導電リード33により正極集電部材31とは電気的に接続され、密閉蓋50のキャップ3が円筒形二次電池1の正極となる。ここで、絶縁リング41は、開口部41aおよび下方に突出する側部41bを有している。絶縁リング41の開口部41a内には接続板35が嵌合されている。
The sealing lid 50 is placed on the upper cylindrical portion 31c of the positive electrode current collecting member 31 in an insulated state. That is, the cap case 37 in which the cap 3 is integrated is placed on the upper end surface of the positive electrode current collecting member 31 in an insulated state via the insulating ring 41. However, the cap case 37 is electrically connected to the positive electrode current collector 31 by the positive electrode conductive lead 33, and the cap 3 of the sealing lid 50 becomes the positive electrode of the cylindrical secondary battery 1. Here, the insulating ring 41 has an opening 41a and a side portion 41b protruding downward. A connection plate 35 is fitted in the opening 41 a of the insulating ring 41.
接続板35は、アルミニウム合金で形成され、中央部を除くほぼ全体が均一でかつ、中央側が少々低い位置に撓んだ、ほぼ皿形状を有している。接続板35の厚さは、例えば、1mm程度である。接続板35の中心には、薄肉でドーム形状に形成された突起部35aが形成されており、突起部35aの周囲には、複数の開口部35bが形成されている。開口部35bは、電池内部に発生するガスを放出する機能を有している。接続板35の突起部35aはキャップケース37の中央部の底面に抵抗溶接または摩擦拡散接合により接合されている。
The connection plate 35 is formed of an aluminum alloy, and has a substantially dish shape in which almost the whole except the central portion is uniform and the central side is bent to a slightly lower position. The thickness of the connection plate 35 is, for example, about 1 mm. A projection 35a that is thin and formed in a dome shape is formed at the center of the connection plate 35, and a plurality of openings 35b are formed around the projection 35a. The opening 35b has a function of releasing gas generated inside the battery. The protrusion 35a of the connection plate 35 is joined to the bottom surface of the central portion of the cap case 37 by resistance welding or friction diffusion bonding.
そして、電池缶60に電極群10を収容し、予め部分アセンブリとして作製された密閉蓋50を正極集電部材31と正極導電リード33により電気的に接続して筒上部に載置する。そして、プレス等により、ガスケット43の外周壁部43bを折曲して基部43aと外周壁部43bにより、密閉蓋50を軸方向に圧接するようにかしめ加工する。これにより、密閉蓋50がガスケット43を介して電池缶60に固定される。
Then, the electrode group 10 is accommodated in the battery can 60, and the sealing lid 50 previously prepared as a partial assembly is electrically connected by the positive electrode current collecting member 31 and the positive electrode conductive lead 33 and placed on the upper part of the cylinder. Then, the outer peripheral wall portion 43b of the gasket 43 is bent by pressing or the like, and the sealing lid 50 is crimped by the base portion 43a and the outer peripheral wall portion 43b so as to be pressed in the axial direction. Thereby, the sealing lid 50 is fixed to the battery can 60 via the gasket 43.
ガスケット43は、当初、リング状の基部43aの周側縁に、上部方向に向けてほぼ垂直に起立して形成された外周壁部43bと、内周側に、基部43aから下方に向けてほぼ垂直に垂下して形成された筒部43cとを有する形状を有している。電池缶60をかしめることにより、密閉蓋50は外周壁部43bを介して電池缶60で挟持される。
The gasket 43 includes an outer peripheral wall portion 43b that is formed to stand substantially vertically toward the upper direction on the peripheral edge of the ring-shaped base portion 43a, and an inner peripheral side substantially downward from the base portion 43a. It has the shape which has the cylinder part 43c formed by dripping vertically. By caulking the battery can 60, the sealing lid 50 is sandwiched by the battery can 60 via the outer peripheral wall 43b.
電池缶60の内部には、非水電解液が所定量注入されている。非水電解液の一例としては、リチウム塩がカーボネート系溶媒に溶解した溶液を用いることが好ましい。リチウム塩の例として、フッ化リン酸リチウム(LiPF6)、フッ化ホウ酸リチウム(LiBF6)、等が挙げられる。また、カーボネート系溶媒の例として、エチレンカーボネート(EC)、ジメチルカーボネート(DMC)、プロピレンカーボネート(PC)、メチルエチルカーボネート(MEC)、或いは上記溶媒の1種類以上から選ばれる溶媒を混合したもの、が挙げられる。
A predetermined amount of non-aqueous electrolyte is injected into the battery can 60. As an example of the non-aqueous electrolyte, it is preferable to use a solution in which a lithium salt is dissolved in a carbonate solvent. Examples of the lithium salt include lithium fluorophosphate (LiPF 6 ), lithium fluoroborate (LiBF 6 ), and the like. Examples of carbonate solvents include ethylene carbonate (EC), dimethyl carbonate (DMC), propylene carbonate (PC), methyl ethyl carbonate (MEC), or a mixture of solvents selected from one or more of the above solvents, Is mentioned.
図3は発電ユニットを説明する図であり、電極群10の構造の詳細を示し、一部を切断した状態の斜視図である。図3に図示されるように、電極群10は、軸芯15の外周に、正極電極11、負極電極12、および第1、第2のセパレータ13、14が捲回された構成を有する。
FIG. 3 is a diagram for explaining the power generation unit, showing the details of the structure of the electrode group 10 and is a perspective view in a state where a part thereof is cut. As shown in FIG. 3, the electrode group 10 has a configuration in which the positive electrode 11, the negative electrode 12, and the first and second separators 13 and 14 are wound around the outer periphery of the shaft core 15.
この電極群10では、軸芯15の外周に接する最内周には第1のセパレータ13が捲回され、その外側を、負極電極12、第2のセパレータ14および正極電極11が、この順に積層され、捲回されている。最内周の負極電極12の内側には第1のセパレータ13および第2のセパレータ14が数周捲回されている。また、最外周は負極電極12およびその外周に捲回された第1のセパレータ13となっている。
In this electrode group 10, the first separator 13 is wound on the innermost periphery that is in contact with the outer periphery of the shaft core 15, and the negative electrode 12, the second separator 14, and the positive electrode 11 are laminated in this order on the outer side. Has been wound up. A first separator 13 and a second separator 14 are wound several times inside the innermost negative electrode 12. The outermost periphery is the negative electrode 12 and the first separator 13 wound around the outer periphery.
正極電極11は、アルミニウム箔により形成され帯形状を有し、正極シート11aと、この正極シート11aの両面に正極合剤11bが塗工された正極処理部(正極合剤層)を有する。正極シート11aの長手方向に沿った上方側の側縁は、正極合剤11bが塗工されずアルミニウム箔が露出した正極合剤未処理部11cとなっている。この正極合剤未処理部11cには、軸芯15と平行に上方に突き出す多数の正極リード16が等間隔に一体的に形成されている。
The positive electrode 11 is formed of an aluminum foil and has a strip shape. The positive electrode 11 includes a positive electrode sheet 11a and a positive electrode processing portion (positive electrode mixture layer) in which the positive electrode mixture 11b is applied to both surfaces of the positive electrode sheet 11a. The upper side edge along the longitudinal direction of the positive electrode sheet 11a is a positive electrode mixture untreated portion 11c where the positive electrode mixture 11b is not applied and the aluminum foil is exposed. In the positive electrode mixture untreated portion 11 c, a large number of positive electrode leads 16 protruding upward in parallel with the shaft core 15 are integrally formed at equal intervals.
正極合剤11bは正極活物質と、正極導電材と、正極バインダと、正極ガス発生化合物からなる。正極活物質はリチウム酸化物が好ましい。例として、コバルト酸リチウム、マンガン酸リチウム、ニッケル酸リチウム、リチウム複合酸化物(コバルト、ニッケル、マンガンから選ばれる2種類以上を含むリチウム酸化物)等が挙げられる。
The positive electrode mixture 11b includes a positive electrode active material, a positive electrode conductive material, a positive electrode binder, and a positive electrode gas generating compound. The positive electrode active material is preferably lithium oxide. Examples include lithium cobaltate, lithium manganate, lithium nickelate, lithium composite oxide (lithium oxide containing two or more selected from cobalt, nickel, and manganese).
正極導電材は、正極合剤中におけるリチウムの吸蔵放出反応で生じた電子の正極電極への伝達を補助できるものであれば制限は無い。正極導電材の例として、黒鉛やアセチレンブラックなどが挙げられる。
The positive electrode conductive material is not limited as long as it can assist the transmission of electrons generated by the occlusion / release reaction of lithium in the positive electrode mixture to the positive electrode. Examples of the positive electrode conductive material include graphite and acetylene black.
正極バインダは、正極活物質と正極導電材を結着させ、また正極合剤と正極集電体を結着させることが可能であり、非水電解液との接触により、大幅に劣化しなければ特に制限はない。正極バインダの例としてポリフッ化ビニリデン(PVDF)やフッ素ゴムなどが挙げられる。
The positive electrode binder can bind the positive electrode active material and the positive electrode conductive material, and can bind the positive electrode mixture and the positive electrode current collector, and should not deteriorate significantly due to contact with the non-aqueous electrolyte. There is no particular limitation. Examples of the positive electrode binder include polyvinylidene fluoride (PVDF) and fluororubber.
正極ガス発生化合物としては、過充電状態の正極電位においてガス発生をする炭酸無機化合物、蓚酸無機化合物、又は、硝酸無機化合物が挙げられる。中でも、炭酸無機化合物が好ましく、例えば炭酸リチウムが挙げられる。正極合剤における炭酸リチウムの含有量は、1重量%以上4重量%以下が好ましいが、実施例1では、1.8重量%とした。
As the positive electrode gas generating compound, an inorganic carbonate compound, an oxalic acid inorganic compound, or a nitric acid inorganic compound that generates gas at a positive electrode potential in an overcharged state can be mentioned. Among these, a carbonic acid inorganic compound is preferable, for example, lithium carbonate. The content of lithium carbonate in the positive electrode mixture is preferably 1 wt% or more and 4 wt% or less, but in Example 1, it was 1.8 wt%.
正極合剤層の形成方法は、正極電極上に正極合剤が形成される方法であれば制限はない。正極合剤11bの形成方法の例として、正極合剤11bの構成物質の分散溶液を正極シート11a上に塗工する方法が挙げられる。
The method for forming the positive electrode mixture layer is not limited as long as the positive electrode mixture is formed on the positive electrode. As an example of a method for forming the positive electrode mixture 11b, a method in which a dispersion solution of constituent materials of the positive electrode mixture 11b is applied on the positive electrode sheet 11a.
正極合剤11bを正極シート11aに塗工する方法の例として、ロール塗工法、スリットダイ塗工法等が挙げられる。正極合剤11bに分散溶液の溶媒例として、N-メチルピロリドン(NMP)や水等を添加し、混練したスラリを、厚さ20μmのアルミニウム箔の両面に均一に塗工し、乾燥させた後、プレスして裁断する。正極合剤11bの塗工厚さの一例としては片側約40μmである。正極シート11aを裁断する際、正極リード16を一体的に形成する。実施例1では、正極電極片面上の正極合剤の塗工量を140g/m2としている。
Examples of the method for applying the positive electrode mixture 11b to the positive electrode sheet 11a include a roll coating method and a slit die coating method. After adding N-methylpyrrolidone (NMP) or water as an example of a solvent for the dispersion solution to the positive electrode mixture 11b and uniformly kneading the slurry on both sides of an aluminum foil having a thickness of 20 μm, and drying it. , Press and cut. An example of the coating thickness of the positive electrode mixture 11b is about 40 μm on one side. When cutting the positive electrode sheet 11a, the positive electrode lead 16 is integrally formed. In Example 1, the coating amount of the positive electrode mixture on one surface of the positive electrode is 140 g / m 2 .
負極電極12は、銅箔により形成され帯形状を有し、負極シート12aと、この負極シート12aの両面に負極合剤12bが塗工された負極処理部(負極合剤層)を有する。負極シート12aの長手方向に沿った下方側の側縁は、負極合剤12bが塗工されず銅箔が露出した負極合剤未処理部12cとなっている。この負極合剤未処理部12cには、正極リード16とは反対方向に延出された、多数の負極リード17が等間隔に一体的に形成されている。
The negative electrode 12 is formed of a copper foil and has a strip shape. The negative electrode 12 includes a negative electrode sheet 12a and a negative electrode treatment portion (negative electrode mixture layer) in which a negative electrode mixture 12b is applied to both surfaces of the negative electrode sheet 12a. The lower side edge along the longitudinal direction of the negative electrode sheet 12a is a negative electrode mixture untreated portion 12c in which the negative electrode mixture 12b is not applied and the copper foil is exposed. In the negative electrode mixture untreated portion 12c, a large number of negative electrode leads 17 extending in the direction opposite to the positive electrode lead 16 are integrally formed at equal intervals.
負極合剤12bは、負極活物質と、負極バインダと、増粘剤とからなる。負極合剤12bは、アセチレンブラックなどの負極導電材を有しても良い。負極活物質としては、黒鉛炭素を用いることが好ましい。黒鉛炭素を用いることにより、大容量が要求されるプラグインハイブリッド自動車や電気自動車向けのリチウムイオン二次電池が作製できる。負極合剤12bの形成方法は、負極シート12a上に負極合剤12bが形成される方法であれば制限はない。負極合剤12bを負極シート12aに塗工する方法の例として、負極合剤12bの構成物質の分散溶液を負極シート12a上に塗工する方法が挙げられる。塗工方法の例として、ロール塗工法、スリットダイ塗工法等が挙げられる。
The negative electrode mixture 12b is composed of a negative electrode active material, a negative electrode binder, and a thickener. The negative electrode mixture 12b may have a negative electrode conductive material such as acetylene black. Graphite carbon is preferably used as the negative electrode active material. By using graphite carbon, a lithium ion secondary battery for a plug-in hybrid vehicle or an electric vehicle requiring a large capacity can be manufactured. The formation method of the negative electrode mixture 12b is not limited as long as the negative electrode mixture 12b is formed on the negative electrode sheet 12a. As an example of a method of applying the negative electrode mixture 12b to the negative electrode sheet 12a, a method of applying a dispersion solution of the constituent material of the negative electrode mixture 12b onto the negative electrode sheet 12a can be mentioned. Examples of the coating method include a roll coating method and a slit die coating method.
負極合剤12bを負極シート12aに塗工する方法の例として、負極合剤12bに分散溶媒としてN-メチル-2-ピロリドンや水を添加し、混練したスラリを、厚さ10μmの圧延銅箔の両面に均一に塗工し、乾燥させた後、プレスして裁断する。負極合剤12bの塗工厚さの一例としては片側約40μmである。負極シート12aを裁断する際、負極リード17を一体的に形成する。
As an example of a method of coating the negative electrode mixture 12b on the negative electrode sheet 12a, N-methyl-2-pyrrolidone or water as a dispersion solvent is added to the negative electrode mixture 12b, and the kneaded slurry is rolled into a 10 μm thick rolled copper foil. After coating uniformly on both sides, press and cut. An example of the coating thickness of the negative electrode mixture 12b is about 40 μm on one side. When the negative electrode sheet 12a is cut, the negative electrode lead 17 is integrally formed.
第1のセパレータ13および第2のセパレータ14の幅をWS、負極シート12aに形成される負極合剤12bの幅をWC、正極シート11aに形成される正極合剤11bの幅をWAとした場合、下記の式を満足するように形成される。
WS>WC>WA The width of thefirst separator 13 and the second separator 14 is W S , the width of the negative electrode mixture 12b formed on the negative electrode sheet 12a is W C , and the width of the positive electrode mixture 11b formed on the positive electrode sheet 11a is W A. In this case, it is formed so as to satisfy the following formula.
W S > W C > W A
WS>WC>WA The width of the
W S > W C > W A
すなわち、正極合剤11bの幅WAよりも、常に、負極合剤12bの幅WCが大きい。これは、リチウムイオン二次電池の場合、正極活物質であるリチウムがイオン化してセパレータを浸透するが、負極側に負極活物質が形成されておらず負極シート12aが露出していると負極シート12aにリチウムが析出し、内部短絡を発生する原因となるからである。
That is, the width W C of the negative electrode mixture 12b is always larger than the width W A of the positive electrode mixture 11b. This is because in the case of a lithium ion secondary battery, lithium as the positive electrode active material is ionized and penetrates the separator, but the negative electrode sheet is not formed on the negative electrode side and the negative electrode sheet 12a is exposed. This is because lithium is deposited on 12a and causes an internal short circuit.
形成された正極電極と負極電極のそれぞれの容量の比である負極容量/正極容量をNP比とした。このNP比は1.1以上が好ましいが、実施例1では、1.4とした。
The negative electrode capacity / positive electrode capacity, which is the ratio of the respective capacities of the formed positive electrode and negative electrode, was defined as the NP ratio. The NP ratio is preferably 1.1 or more, but in Example 1, it was set to 1.4.
(実施例1)
上述のように、実施例1の二次電池では、正極合剤における炭酸リチウムの含有量を1.8重量%、NP比を1.4、正極電極片面上の正極合剤の塗工量を140g/m2とした。 (Example 1)
As described above, in the secondary battery of Example 1, the lithium carbonate content in the positive electrode mixture was 1.8 wt%, the NP ratio was 1.4, and the coating amount of the positive electrode mixture on one surface of the positive electrode was 140 g / m 2 .
上述のように、実施例1の二次電池では、正極合剤における炭酸リチウムの含有量を1.8重量%、NP比を1.4、正極電極片面上の正極合剤の塗工量を140g/m2とした。 (Example 1)
As described above, in the secondary battery of Example 1, the lithium carbonate content in the positive electrode mixture was 1.8 wt%, the NP ratio was 1.4, and the coating amount of the positive electrode mixture on one surface of the positive electrode was 140 g / m 2 .
(実施例2)
正極合剤の塗工量を130g/m2になるように作製する以外は、実施例1と同様の方法で実施例2の二次電池を作製した。 (Example 2)
A secondary battery of Example 2 was produced in the same manner as in Example 1 except that the coating amount of the positive electrode mixture was 130 g / m 2 .
正極合剤の塗工量を130g/m2になるように作製する以外は、実施例1と同様の方法で実施例2の二次電池を作製した。 (Example 2)
A secondary battery of Example 2 was produced in the same manner as in Example 1 except that the coating amount of the positive electrode mixture was 130 g / m 2 .
(実施例3)
正極合剤の塗工量を120g/m2になるように作製する以外は、実施例1と同様の方法で実施例3の二次電池を作製した。 (Example 3)
A secondary battery of Example 3 was produced in the same manner as in Example 1 except that the coating amount of the positive electrode mixture was 120 g / m 2 .
正極合剤の塗工量を120g/m2になるように作製する以外は、実施例1と同様の方法で実施例3の二次電池を作製した。 (Example 3)
A secondary battery of Example 3 was produced in the same manner as in Example 1 except that the coating amount of the positive electrode mixture was 120 g / m 2 .
(実施例4)
正極合剤の塗工量を110g/m2になるように作製する以外は、実施例1と同様の方法で実施例4の二次電池を作製した。 Example 4
A secondary battery of Example 4 was produced in the same manner as in Example 1, except that the coating amount of the positive electrode mixture was 110 g / m 2 .
正極合剤の塗工量を110g/m2になるように作製する以外は、実施例1と同様の方法で実施例4の二次電池を作製した。 Example 4
A secondary battery of Example 4 was produced in the same manner as in Example 1, except that the coating amount of the positive electrode mixture was 110 g / m 2 .
(実施例5)
NPを1.5になるように作製する以外は、実施例1と同様の方法で実施例5の二次電池を作製した。 (Example 5)
A secondary battery of Example 5 was made in the same manner as in Example 1 except that NP was made to be 1.5.
NPを1.5になるように作製する以外は、実施例1と同様の方法で実施例5の二次電池を作製した。 (Example 5)
A secondary battery of Example 5 was made in the same manner as in Example 1 except that NP was made to be 1.5.
(比較例1)
正極合剤の塗工量を110g/m2、NP比を1.1になるように作製する以外は、実施例1と同様の方法で比較例1の二次電池を作製した。 (Comparative Example 1)
A secondary battery of Comparative Example 1 was fabricated in the same manner as in Example 1 except that the coating amount of the positive electrode mixture was 110 g / m 2 and the NP ratio was 1.1.
正極合剤の塗工量を110g/m2、NP比を1.1になるように作製する以外は、実施例1と同様の方法で比較例1の二次電池を作製した。 (Comparative Example 1)
A secondary battery of Comparative Example 1 was fabricated in the same manner as in Example 1 except that the coating amount of the positive electrode mixture was 110 g / m 2 and the NP ratio was 1.1.
(比較例2)
正極合剤の塗工量を110g/m2、NP比を1.2になるように作製する以外は、実施例1と同様の方法で比較例2の二次電池を作製した。 (Comparative Example 2)
A secondary battery of Comparative Example 2 was fabricated in the same manner as in Example 1 except that the coating amount of the positive electrode mixture was 110 g / m 2 and the NP ratio was 1.2.
正極合剤の塗工量を110g/m2、NP比を1.2になるように作製する以外は、実施例1と同様の方法で比較例2の二次電池を作製した。 (Comparative Example 2)
A secondary battery of Comparative Example 2 was fabricated in the same manner as in Example 1 except that the coating amount of the positive electrode mixture was 110 g / m 2 and the NP ratio was 1.2.
(比較例3)
正極合剤の塗工量を90g/m2、NP比を1.2になるように作製する以外は、実施例1と同様の方法で比較例2の二次電池を作製した。 (Comparative Example 3)
A secondary battery of Comparative Example 2 was fabricated in the same manner as in Example 1 except that the coating amount of the positive electrode mixture was 90 g / m 2 and the NP ratio was 1.2.
正極合剤の塗工量を90g/m2、NP比を1.2になるように作製する以外は、実施例1と同様の方法で比較例2の二次電池を作製した。 (Comparative Example 3)
A secondary battery of Comparative Example 2 was fabricated in the same manner as in Example 1 except that the coating amount of the positive electrode mixture was 90 g / m 2 and the NP ratio was 1.2.
(比較例4)
NP比を1.3になるように作製する以外は、実施例1と同様の方法で比較例2の二次電池を作製した。 (Comparative Example 4)
A secondary battery of Comparative Example 2 was produced in the same manner as in Example 1 except that the NP ratio was made to be 1.3.
NP比を1.3になるように作製する以外は、実施例1と同様の方法で比較例2の二次電池を作製した。 (Comparative Example 4)
A secondary battery of Comparative Example 2 was produced in the same manner as in Example 1 except that the NP ratio was made to be 1.3.
(比較例5)
正極合剤の塗工量を130g/m2、NP比を1.3になるように作製する以外は、実施例1と同様の方法で比較例5の二次電池を作製した。 (Comparative Example 5)
A secondary battery of Comparative Example 5 was fabricated in the same manner as in Example 1 except that the coating amount of the positive electrode mixture was 130 g / m 2 and the NP ratio was 1.3.
正極合剤の塗工量を130g/m2、NP比を1.3になるように作製する以外は、実施例1と同様の方法で比較例5の二次電池を作製した。 (Comparative Example 5)
A secondary battery of Comparative Example 5 was fabricated in the same manner as in Example 1 except that the coating amount of the positive electrode mixture was 130 g / m 2 and the NP ratio was 1.3.
(比較例6)
正極合剤の塗工量を120g/m2、NP比を1.3になるように作製する以外は、実施例1と同様の方法で比較例6の二次電池を作製した。 (Comparative Example 6)
A secondary battery of Comparative Example 6 was fabricated in the same manner as in Example 1 except that the coating amount of the positive electrode mixture was 120 g / m 2 and the NP ratio was 1.3.
正極合剤の塗工量を120g/m2、NP比を1.3になるように作製する以外は、実施例1と同様の方法で比較例6の二次電池を作製した。 (Comparative Example 6)
A secondary battery of Comparative Example 6 was fabricated in the same manner as in Example 1 except that the coating amount of the positive electrode mixture was 120 g / m 2 and the NP ratio was 1.3.
本発明は、円筒形二次電池に限定されるものではなく、角形二次電池にも適用することができる。図4は蓄電素子の一実施の形態としての角形二次電池100の外観斜視図であり、図5は角形二次電池100の構成を示す分解斜視図である。
The present invention is not limited to a cylindrical secondary battery but can also be applied to a prismatic secondary battery. FIG. 4 is an external perspective view of a prismatic secondary battery 100 as an embodiment of the electricity storage device, and FIG. 5 is an exploded perspective view showing the configuration of the prismatic secondary battery 100.
図4に示すように、角形二次電池100は、電池缶101と電池蓋102とからなる電池容器を備えている。電池缶101および電池蓋102の材質は、アルミニウムまたはアルミニウム合金などである。電池缶101は、深絞り加工を施すことによって、一端が開口された扁平な矩形箱状に形成されている。電池缶101は、矩形平板状の底板101cと、底板101cの一対の長辺部のそれぞれから立ち上がる一対の幅広側板101aと、底板101cの一対の短辺部のそれぞれから立ち上がる一対の幅狭側板101bとを有している。
As shown in FIG. 4, the square secondary battery 100 includes a battery container including a battery can 101 and a battery lid 102. The material of the battery can 101 and the battery lid 102 is aluminum or an aluminum alloy. The battery can 101 is formed in a flat rectangular box shape with one end opened by performing deep drawing. The battery can 101 includes a rectangular plate-like bottom plate 101c, a pair of wide side plates 101a rising from each of a pair of long sides of the bottom plate 101c, and a pair of narrow side plates 101b rising from each of a pair of short sides of the bottom plate 101c. And have.
図5に示すように、電池缶101には捲回電極群170(図6参照)が収容されている。捲回電極群170の正極電極174に接合される正極集電体180および捲回電極群170の負極電極175に接合される。負極集電体190ならびに捲回電極群170は、捲回電極群の中央部を覆う絶縁シート108aと捲回電極群の正極未塗工部を覆う絶縁シート108bと捲回電極群の負極未塗工部を覆う絶縁シート108cに覆われた状態で電池缶101に収容されている。絶縁シート108a、108b、108cの材質は、ポリプロピレン等の絶縁性を有する樹脂であり、電池缶101と、捲回電極群170とは電気的に絶縁されている。
As shown in FIG. 5, the battery can 101 accommodates a wound electrode group 170 (see FIG. 6). The positive electrode current collector 180 joined to the positive electrode 174 of the wound electrode group 170 and the negative electrode 175 of the wound electrode group 170 are joined. The negative electrode current collector 190 and the wound electrode group 170 are composed of an insulating sheet 108a covering the center of the wound electrode group, an insulating sheet 108b covering the positive electrode uncoated part of the wound electrode group, and a negative electrode uncoated of the wound electrode group. It is accommodated in the battery can 101 in a state covered with an insulating sheet 108c covering the construction part. The material of the insulating sheets 108a, 108b, 108c is an insulating resin such as polypropylene, and the battery can 101 and the wound electrode group 170 are electrically insulated.
図4および図5に示すように、電池蓋102は、矩形平板状であって、電池缶101の開口を塞ぐようにレーザー溶接されている。つまり、電池蓋102は、電池缶101の開口を封止している。図1に示すように、電池蓋102には、捲回電極群170の正極電極174および負極電極175と電気的に接続された正極外部端子104および負極外部端子105が配置されている。
4 and 5, the battery lid 102 has a rectangular flat plate shape and is laser-welded so as to close the opening of the battery can 101. That is, the battery lid 102 seals the opening of the battery can 101. As shown in FIG. 1, a positive electrode external terminal 104 and a negative electrode external terminal 105 that are electrically connected to the positive electrode 174 and the negative electrode 175 of the wound electrode group 170 are disposed on the battery lid 102.
図5に示すように、正極外部端子104は電流遮断機構181と正極集電体180を介して捲回電極群170の正極電極174(図3参照)に電気的に接続され、負極外部端子105は負極集電体190を介して捲回電極群170の負極電極175に電気的に接続されている。このため、正極外部端子104および負極外部端子105を介して外部機器に電力が供給され、あるいは、正極外部端子104および負極外部端子105を介して外部発電電力が捲回電極群170に供給されて充電される。
As shown in FIG. 5, the positive external terminal 104 is electrically connected to the positive electrode 174 (see FIG. 3) of the wound electrode group 170 via the current interrupt mechanism 181 and the positive current collector 180, and the negative external terminal 105. Is electrically connected to the negative electrode 175 of the wound electrode group 170 via the negative electrode current collector 190. Therefore, electric power is supplied to the external device via the positive external terminal 104 and the negative external terminal 105, or external generated power is supplied to the wound electrode group 170 via the positive external terminal 104 and the negative external terminal 105. Charged.
図5に示すように、電池蓋102には、電池容器内に電解液を注入するための注液孔106aが穿設されている。注液孔106aは、電解液注入後に注液栓106bによって封止される。電解液としては、たとえば、エチレンカーボネート等の炭酸エステル系の有機溶媒に6フッ化リン酸リチウム(LiPF6)等のリチウム塩が溶解された非水電解液を用いることができる。
As shown in FIG. 5, the battery lid 102 is provided with a liquid injection hole 106 a for injecting an electrolytic solution into the battery container. The liquid injection hole 106a is sealed by a liquid injection plug 106b after the electrolytic solution is injected. As the electrolytic solution, for example, a non-aqueous electrolytic solution in which a lithium salt such as lithium hexafluorophosphate (LiPF 6 ) is dissolved in a carbonate-based organic solvent such as ethylene carbonate can be used.
電池蓋102には、ガス排出弁103が設けられている。ガス排出弁103は、プレス加工によって電池蓋102を部分的に薄肉化することで形成されている。なお、薄膜部材を電池蓋102の開口にレーザー溶接等により取り付けて、薄肉部分をガス排出弁としてもよい。ガス排出弁103は、角形二次電池100が内部短絡等の異常により発熱してガスが発生し、電池容器内の圧力が上昇して所定圧力に達したときに開裂して、内部からガスを排出することで電池容器内の圧力を低減させる。
The battery cover 102 is provided with a gas discharge valve 103. The gas discharge valve 103 is formed by partially thinning the battery lid 102 by press working. The thin-walled member may be attached to the opening of the battery lid 102 by laser welding or the like, and the thin portion may be used as a gas discharge valve. The gas discharge valve 103 is heated when the rectangular secondary battery 100 generates heat due to an abnormality such as an internal short circuit, and gas is generated. By discharging, the pressure in the battery container is reduced.
電流遮断機構181は、角形二次電池100が過充電状態となり、そのときの正極電位により正極ガス発生化合物が分解し、ガスが発生して、内圧が上昇した場合に作動する。電流遮断機構181は、例えばダイアフラムを有しており、電池容器内が所定の作動圧、例えば0.4MPa以上1.0MPa以下の範囲の圧力となったときにダイアフラムが変形して接点を遮断する構成を有する。
The current interruption mechanism 181 operates when the square secondary battery 100 is overcharged, the positive electrode gas generating compound is decomposed by the positive electrode potential at that time, gas is generated, and the internal pressure is increased. The current interruption mechanism 181 has, for example, a diaphragm, and when the inside of the battery container reaches a predetermined operating pressure, for example, a pressure in a range of 0.4 MPa to 1.0 MPa, the diaphragm is deformed to interrupt the contact. It has a configuration.
図6を参照して、捲回電極群170について説明する。図6は捲回電極群170を示す斜視図であり、捲回電極群170の巻き終り側を展開した状態を示している。発電要素である捲回電極群170は、帯状の正極電極174および負極電極175をセパレータ173a,173bを介在させて捲回中心軸W周りに扁平形状に捲回することで積層構造とされている。
The wound electrode group 170 will be described with reference to FIG. FIG. 6 is a perspective view showing the wound electrode group 170 and shows a state where the winding end side of the wound electrode group 170 is developed. The wound electrode group 170, which is a power generation element, has a laminated structure by winding a belt-like positive electrode 174 and a negative electrode 175 in a flat shape around the wound central axis W with separators 173a and 173b interposed. .
正極電極174は、正極箔171の両面に正極合剤層176が形成されてなる。正極合剤は、正極活物質に結着材(バインダ)と正極ガス発生化合物が配合されたものである。正極ガス発生化合物としては、過充電状態の正極電位においてガス発生をする炭酸無機化合物、蓚酸無機化合物、又は、硝酸無機化合物が挙げられる。中でも、炭酸無機化合物が好ましく、例えば炭酸リチウムが挙げられる。
負極電極175は、負極箔172の両面に負極合剤層177が形成されてなる。負極合剤は、負極活物質に結着材(バインダ)が配合されたものである。 Thepositive electrode 174 has a positive electrode mixture layer 176 formed on both surfaces of the positive electrode foil 171. The positive electrode mixture is a mixture of a positive electrode active material and a binder (binder) and a positive gas generating compound. Examples of the positive electrode gas generating compound include a carbonic acid inorganic compound, an oxalic acid inorganic compound, or a nitric acid inorganic compound that generates gas at a positive electrode potential in an overcharged state. Among these, a carbonic acid inorganic compound is preferable, for example, lithium carbonate.
Thenegative electrode 175 has a negative electrode mixture layer 177 formed on both surfaces of a negative electrode foil 172. The negative electrode mixture is a mixture of a negative electrode active material and a binder.
負極電極175は、負極箔172の両面に負極合剤層177が形成されてなる。負極合剤は、負極活物質に結着材(バインダ)が配合されたものである。 The
The
正極箔171は、厚さ20~30μm程度のアルミニウム箔であり、負極箔172は、厚さ15~20μm程度の銅箔である。セパレータ173a,173bの素材はリチウムイオンが通過可能な微多孔質のポリエチレン樹脂である。正極活物質はマンガン酸リチウム等のリチウム含有遷移金属複酸化物であり、負極活物質はリチウムイオンを可逆に吸蔵、放出可能な黒鉛等の炭素材である。
The positive foil 171 is an aluminum foil having a thickness of about 20 to 30 μm, and the negative foil 172 is a copper foil having a thickness of about 15 to 20 μm. The material of the separators 173a and 173b is a microporous polyethylene resin through which lithium ions can pass. The positive electrode active material is a lithium-containing transition metal double oxide such as lithium manganate, and the negative electrode active material is a carbon material such as graphite capable of reversibly occluding and releasing lithium ions.
捲回電極群170の幅方向、すなわち捲回方向に直交する捲回中心軸Wの方向の両端部は、一方が正極電極174の積層部とされ、他方が負極電極175の積層部とされている。一端に設けられる正極電極174の積層部は、正極合剤層176が形成されていない正極未塗工部、すなわち正極箔171の露出部が積層されたものである。他端に設けられる負極電極175の積層部は、負極合剤層177が形成されていない負極未塗工部、すなわち負極箔172の露出部が積層されたものである。正極未塗工部の積層部および負極未塗工部の積層部は、それぞれ予め押し潰され、それぞれ正極集電体180および負極集電体190に超音波接合により接続される。
One of the end portions of the winding electrode group 170 in the width direction, that is, the direction of the winding central axis W perpendicular to the winding direction is a laminated portion of the positive electrode 174 and the other is a laminated portion of the negative electrode 175. Yes. The laminated portion of the positive electrode 174 provided at one end is obtained by laminating an uncoated positive electrode portion where the positive electrode mixture layer 176 is not formed, that is, an exposed portion of the positive foil 171. The laminated portion of the negative electrode 175 provided at the other end is obtained by laminating the negative electrode uncoated portion where the negative electrode mixture layer 177 is not formed, that is, the exposed portion of the negative electrode foil 172. The laminated portion of the positive electrode uncoated portion and the laminated portion of the negative electrode uncoated portion are respectively crushed in advance and connected to the positive electrode current collector 180 and the negative electrode current collector 190 by ultrasonic bonding, respectively.
続いて、図7は実施例1~5と比較例1~6の円筒形二次電池の正極合剤の塗工量とNP比の構成を示す表である。実施例1~5と比較例1~6では、炭酸リチウムの含有量は1.8重量%(wt%)である。
Subsequently, FIG. 7 is a table showing the composition of the coating amount and the NP ratio of the positive electrode mixture of the cylindrical secondary batteries of Examples 1 to 5 and Comparative Examples 1 to 6. In Examples 1 to 5 and Comparative Examples 1 to 6, the lithium carbonate content is 1.8 wt% (wt%).
図8は実施例1~5と比較例1~6の過充電試験の試験結果を示す表である。
全ての電池は、試験前、10A、4.2V、3時間の定電流定電圧充電により充電末状態とした。温度25℃にて、それぞれの電池に対して、通電された積算電気量を知ることのできる直流電源を用いて8.4V、10Aの直流を印加した。電流遮断機構が作動し、電池温度が20℃付近になることをもって試験の終了とした。 FIG. 8 is a table showing test results of overcharge tests of Examples 1 to 5 and Comparative Examples 1 to 6.
All the batteries were put into the end-of-charge state by constant current and constant voltage charging for 10 hours, 10 A, 4.2 V, and 3 hours before the test. At a temperature of 25 ° C., a direct current of 8.4 V and 10 A was applied to each battery using a direct current power source capable of knowing the accumulated amount of electricity supplied. The test was terminated when the current interruption mechanism was activated and the battery temperature was around 20 ° C.
全ての電池は、試験前、10A、4.2V、3時間の定電流定電圧充電により充電末状態とした。温度25℃にて、それぞれの電池に対して、通電された積算電気量を知ることのできる直流電源を用いて8.4V、10Aの直流を印加した。電流遮断機構が作動し、電池温度が20℃付近になることをもって試験の終了とした。 FIG. 8 is a table showing test results of overcharge tests of Examples 1 to 5 and Comparative Examples 1 to 6.
All the batteries were put into the end-of-charge state by constant current and constant voltage charging for 10 hours, 10 A, 4.2 V, and 3 hours before the test. At a temperature of 25 ° C., a direct current of 8.4 V and 10 A was applied to each battery using a direct current power source capable of knowing the accumulated amount of electricity supplied. The test was terminated when the current interruption mechanism was activated and the battery temperature was around 20 ° C.
また、それぞれの過充電試験の結果、通電された積算電気量に基づき、試験終了時におけるそれぞれの電池の充電深度をSOC%にて示した。なお、SOC100%は過充電試験前の状態と対応している。
Also, as a result of each overcharge test, the charge depth of each battery at the end of the test was indicated in SOC% based on the accumulated amount of electricity supplied. Note that SOC 100% corresponds to the state before the overcharge test.
図8に示されている過充電試験結果は、試験中電池発熱最高温度(℃)、電流遮断機構作動SOC(%)、過充電容量(Ah)である。
The overcharge test results shown in FIG. 8 are the battery heat generation maximum temperature (° C.), the current interruption mechanism operation SOC (%), and the overcharge capacity (Ah) during the test.
比較例1と3の試験結果に示されるように、電池発熱に起因する過充電容量と電池内部抵抗をそれぞれ低減させるために正極合剤の塗工量を減らしていくと、二次電池内における炭酸リチウム量の絶対量が減少して、電流遮断機構の作動SOC(%)が増加傾向となることが分かった。さらに、過充電に対する安全性が低下して過度の高温状態(過温)に至る事象が確認された。
As shown in the test results of Comparative Examples 1 and 3, when the coating amount of the positive electrode mixture is decreased in order to reduce the overcharge capacity and the battery internal resistance due to the battery heat generation, It has been found that the absolute amount of lithium carbonate decreases and the operating SOC (%) of the current interrupt mechanism tends to increase. Furthermore, an event was confirmed in which safety against overcharging was reduced and an excessively high temperature state (overtemperature) was reached.
次に、比較例1と比較例2、及び実施例1と実施例5の試験結果に示されるように、NP比の増加に応じて負極電極における正極電極からのリチウム受入れ能力が増加して過充電容量が低減し、電池発熱が低減された。また、過充電時のリチウムデンドライト析出の抑制にもつながり、過充電に対する安全性が向上した。ただし、NP比を増加させすぎると、電池内部抵抗(DCR)が増加し、電池温度が上昇し、過充電時の安全性が低下することが推測される。さらに、図8では、請求項で示している過充電時の安全性が向上する範囲をそれぞれ示している。
Next, as shown in the test results of Comparative Example 1 and Comparative Example 2 and Example 1 and Example 5, as the NP ratio increases, the ability of the negative electrode to receive lithium from the positive electrode increases and excessively increases. The charge capacity was reduced and the battery heat generation was reduced. Moreover, it led to suppression of lithium dendrite precipitation during overcharging, and safety against overcharging was improved. However, if the NP ratio is increased too much, it is estimated that the battery internal resistance (DCR) increases, the battery temperature rises, and the safety during overcharge decreases. Furthermore, in FIG. 8, the range which the safety | security at the time of the overcharge shown by the claim improves is each shown.
請求項1の範囲の正極合剤の塗工量110g/m2の境界線は、電池内炭酸リチウムの絶対量が正極合剤の塗工量110g/m2の含有量以上の境界である。また、NP比1.4の境界線は、過充電容量が14Ah以下となり、電池発熱最高温度が120℃以下である過充電時の安全性が高い境界である。正極合剤の塗工量140g/m2の境界線は、NP比1.4以上で過充電容量が14Ah以下となり、電池発熱最高温度が120℃以下の結果であり、過充電時の安全性が高い境界を確認できたため、設定している。NP比2.0の境界は、NP比1.4と比較して1.3倍以上の内部抵抗上昇が予想され、電池発熱が顕著となってしまうことが予想されるので、設定している。
The boundary line of the coating amount 110 g / m 2 of the positive electrode mixture in the range of claim 1 is a boundary where the absolute amount of lithium carbonate in the battery is not less than the content of the coating amount 110 g / m 2 of the positive electrode mixture. Moreover, the boundary line of NP ratio 1.4 is a boundary with high safety | security at the time of an overcharge whose overcharge capacity will be 14 Ah or less, and battery heat generation maximum temperature is 120 degrees C or less. The boundary line of the coating amount of the positive electrode mixture of 140 g / m 2 is the result of the NP ratio of 1.4 or more, the overcharge capacity of 14 Ah or less, and the maximum battery heat generation temperature of 120 ° C. or less. Is set because a high boundary was confirmed. The boundary of the NP ratio 2.0 is set because an internal resistance increase of 1.3 times or more is expected compared to the NP ratio 1.4, and battery heat generation is expected to become remarkable.
請求項2の範囲は請求項1に対して、さらに過充電時の安全性向上が見込める範囲を示している。
The range of claim 2 shows the range where safety improvement at the time of overcharge can be expected with respect to claim 1.
請求項3の範囲は請求項2に対して、さらに過充電時の安全性向上が見込める範囲を示している。
The range of claim 3 shows the range in which the safety improvement at the time of overcharge can be expected with respect to claim 2.
請求項4のポイントは、最も過充電時の安全性向上が見込める正極合剤の塗工量とNP比の構成を示している。
The point of Claim 4 has shown the structure of the coating amount and NP ratio of the positive mix which can anticipate the safety | security improvement at the time of an overcharge most.
以上、本発明の実施形態について詳述したが、本発明は、前記の実施形態に限定されるものではなく、特許請求の範囲に記載された本発明の精神を逸脱しない範囲で、種々の設計変更を行うことができるものである。例えば、前記した実施の形態は本発明を分かりやすく説明するために詳細に説明したものであり、必ずしも説明した全ての構成を備えるものに限定されるものではない。また、ある実施形態の構成の一部を他の実施形態の構成に置き換えることが可能であり、また、ある実施形態の構成に他の実施形態の構成を加えることも可能である。さらに、各実施形態の構成の一部について、他の構成の追加・削除・置換をすることが可能である。
Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various designs can be made without departing from the spirit of the present invention described in the claims. It can be changed. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described. Further, a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment. Furthermore, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.
1 円筒形二次電池
10 電極群
50 密閉蓋
60 電池缶
61 かしめ部
63 グルービング部
100 角形二次電池
101c 底板
101a 幅広側板
101b 幅狭側板
101 電池缶
102 電池蓋
107 蓋組立体
170 捲回電極群
174 正極電極
175 負極電極
176 正極合剤層
177 負極合剤層
180 正極集電体
181 電流遮断機構 DESCRIPTION OF SYMBOLS 1 Cylindricalsecondary battery 10 Electrode group 50 Sealing lid 60 Battery can 61 Caulking part 63 Grooving part 100 Rectangular secondary battery 101c Bottom plate 101a Wide side plate 101b Narrow side plate 101 Battery can 102 Battery lid 107 Lid assembly 170 Winding electrode group 174 Positive electrode 175 Negative electrode 176 Positive electrode mixture layer 177 Negative electrode mixture layer 180 Positive electrode current collector 181 Current interruption mechanism
10 電極群
50 密閉蓋
60 電池缶
61 かしめ部
63 グルービング部
100 角形二次電池
101c 底板
101a 幅広側板
101b 幅狭側板
101 電池缶
102 電池蓋
107 蓋組立体
170 捲回電極群
174 正極電極
175 負極電極
176 正極合剤層
177 負極合剤層
180 正極集電体
181 電流遮断機構 DESCRIPTION OF SYMBOLS 1 Cylindrical
Claims (5)
- 正極合剤が塗工された正極電極と、負極合剤が塗工された負極電極と、前記正極電極と前記負極電極を収容する電池容器と、該電池容器の内圧が所定の作動圧となったときに電流を遮断する電流遮断機構と、を有する二次電池であって、
前記正極合剤には1重量%以上4重量%以下の炭酸リチウムを含み、
前記正極電極の容量と前記負極電極の容量との比であるNP比が1.4以上2.0以下であり、前記正極合剤の塗工量が110g/m2以上140g/m2以下であることを特徴とする二次電池。 A positive electrode coated with a positive electrode mixture, a negative electrode coated with a negative electrode mixture, a battery container containing the positive electrode and the negative electrode, and the internal pressure of the battery container becomes a predetermined operating pressure A secondary battery having a current interruption mechanism for interrupting current when
The positive electrode mixture includes 1 to 4% by weight of lithium carbonate,
The NP ratio, which is the ratio between the capacity of the positive electrode and the capacity of the negative electrode, is 1.4 or more and 2.0 or less, and the coating amount of the positive electrode mixture is 110 g / m 2 or more and 140 g / m 2 or less. A secondary battery characterized by being. - 前記NP比が1.4以上1.6以下であり、前記正極合剤の塗工量が120g/m2以上140g/m2以下であることを特徴とする請求項1に記載の二次電池。 2. The secondary battery according to claim 1, wherein the NP ratio is 1.4 or more and 1.6 or less, and the coating amount of the positive electrode mixture is 120 g / m 2 or more and 140 g / m 2 or less. .
- 前記NP比が1.5であり、前記正極合剤の塗工量が130g/m2以上140g/m2以下であることを特徴とする請求項2に記載の二次電池。 The secondary battery according to claim 2, wherein the NP ratio is 1.5, and the coating amount of the positive electrode mixture is 130 g / m 2 or more and 140 g / m 2 or less.
- 前記正極合剤の塗工量が130g/m2であることを特徴とする請求項3に記載の二次電池。 The secondary battery according to claim 3, wherein a coating amount of the positive electrode mixture is 130 g / m 2 .
- 前記電流遮断機構の前記作動圧が0.4MPa以上1.0MPa以下であることを特徴とする請求項1に記載の二次電池。 The secondary battery according to claim 1, wherein the operating pressure of the current interrupt mechanism is 0.4 MPa or more and 1.0 MPa or less.
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