WO2019111644A1 - Batterie rechargeable - Google Patents

Batterie rechargeable Download PDF

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Publication number
WO2019111644A1
WO2019111644A1 PCT/JP2018/041908 JP2018041908W WO2019111644A1 WO 2019111644 A1 WO2019111644 A1 WO 2019111644A1 JP 2018041908 W JP2018041908 W JP 2018041908W WO 2019111644 A1 WO2019111644 A1 WO 2019111644A1
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WO
WIPO (PCT)
Prior art keywords
negative electrode
positive electrode
secondary battery
capacity
mah
Prior art date
Application number
PCT/JP2018/041908
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English (en)
Japanese (ja)
Inventor
貴宏 相馬
八木　陽心
Original Assignee
日立オートモティブシステムズ株式会社
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Publication of WO2019111644A1 publication Critical patent/WO2019111644A1/fr

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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
    • 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
    • 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
    • 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
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • 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
    • 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.
  • lithium ion batteries are used as secondary batteries in electric vehicles and hybrid vehicles.
  • Such secondary batteries are required to have high output, high energy density and safety.
  • it is necessary to prevent the safety of the battery system from being impaired even if the secondary battery is overcharged due to an erroneous operation or the like. Therefore, in order to ensure safety in the event of overcharging, a secondary battery is provided with a current interrupting mechanism.
  • Patent Document 1 describes a battery system in which lithium carbonate is contained in a positive electrode mixture as a gas generating agent, and lithium carbonate generates a decomposition gas to operate a current interrupting mechanism when overcharged.
  • Patent Document 1 does not specify the charge capacity of the negative electrode up to the potential at which a decomposition gas is generated at the time of overcharge. For example, when the charge capacity of the negative electrode is small before reaching the reaction potential of the gas generating agent in the overcharged state, lithium is deposited on the surface of the negative electrode, and breaks through the separator separating the positive and negative electrodes, There is a possibility that the secondary battery may be damaged due to a short circuit between the positive and negative electrodes.
  • the battery container accommodating the positive electrode and the negative electrode, and the internal pressure of the battery container reach a predetermined operating pressure
  • a current blocking mechanism for interrupting a current flowing between the positive electrode and the negative electrode, wherein the positive electrode mixture contains a gas generating agent, and the potential of the positive electrode is the secondary battery.
  • the capacity until the reaction potential of the gas generating agent is exceeded by exceeding the charge termination voltage of the battery is more than the capacity until the potential of the negative electrode exceeds the charge termination voltage of the secondary battery and reaches the charge termination voltage of the negative electrode. I made it smaller.
  • a secondary battery excellent in overcharge safety can be provided.
  • FIG. 1 is a longitudinal sectional view of a cylindrical secondary battery 1.
  • 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 such that the power generation unit 20 is accommodated inside a bottomed cylindrical battery can 60 whose opening is sealed by a sealing lid 50. First, the battery can 60 and the power generation unit 20 will be described, and next, the sealing lid 50 will be described.
  • a caulking portion 61 is formed at the can opening end (upper side in the figure).
  • the caulking portion 61 includes a bent portion 62 formed by bending the can open end inward, and a grooving portion 63 protruding inward at a predetermined distance on the battery bottom side.
  • the sealing lid 50 is crimped and fixed by interposing the gasket 43 between the bent portion 62 and the grooving portion 63, and the cylindrical secondary battery 1 is sealed.
  • the power generation unit 20 is integrally configured by unitizing 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 an axial core 15 at the central portion, and a positive electrode, a negative electrode and a separator are wound around the axial core 15.
  • the hollow cylindrical shaft core 15 has a large diameter recess 15a formed 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 made of, for example, aluminum, and a disk-like base 31a, a lower cylindrical portion 31b which protrudes toward the shaft core 15 at the inner peripheral portion of the base 31a and is pressed into the inner surface of the shaft core 15. And an upper cylindrical portion 31 c protruding toward the sealing lid 50 at the outer peripheral edge.
  • the base 31 a of the positive electrode current collecting member 31 is formed with an opening 31 d for releasing a decomposition gas generated inside the battery at the time of overcharging.
  • the positive electrode leads 16 of the positive electrode sheet 11 a described in detail later with reference to FIG. 3 are all welded to the upper cylindrical portion 31 c of the positive electrode current collecting member 31.
  • the positive electrode lead 16 is overlapped and joined onto the upper cylindrical portion 31 c of the positive electrode current collecting member 31. Since each positive electrode lead 16 is very thin, one can not take out a large current. For this reason, a large number of positive electrode leads 16 are formed at predetermined intervals over the entire length from the winding start to the winding end on the shaft core 15.
  • the positive electrode lead 16 of the positive electrode sheet 11 a and the ring-shaped pressing member 32 are welded to the outer periphery of the upper cylindrical portion 31 c of the positive electrode current collecting member 31.
  • the large number of positive electrode leads 16 are in close contact with the outer periphery of the upper cylindrical portion 31c of the positive electrode current collecting member 31, and the pressing member 32 is wound around the outer periphery of the positive electrode lead 16 and temporarily fixed.
  • 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. As soon as the surface is exposed by processing, aluminum forms an aluminum oxide film on the surface, and this aluminum oxide film can prevent oxidation by the electrolytic solution. Further, by forming the positive electrode current collecting member 31 of aluminum, it is possible to weld the positive electrode lead 16 of the positive electrode sheet 11a by ultrasonic welding, spot welding or the like.
  • a stepped portion 15 b whose outer diameter is reduced in 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 stepped portion 15 b.
  • the negative electrode current collecting member 21 is formed of, for example, copper, and an opening 21b which is press-fit into the step 15b of the shaft core 15 is formed in the disk-shaped base 21a.
  • An outer peripheral tubular portion 21c is formed to protrude.
  • the negative electrode leads 17 of the negative electrode sheet 12a described in detail in FIG. 3 to be described later are 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, many are formed at predetermined intervals over the entire length from the winding start to the winding end to the shaft core 15 in order to take out a large current.
  • the negative electrode lead 17 of the negative electrode sheet 12 a and the ring-shaped pressing member 22 are welded to the outer periphery of the outer peripheral cylindrical portion 21 c of the negative electrode current collecting member 21.
  • the large number of negative electrode leads 17 are in close contact with the outer periphery of the outer peripheral cylindrical portion 21 c of the negative electrode current collecting member 21, and the pressing member 22 is wound around and temporarily fixed to the outer periphery of the negative electrode lead 17.
  • a copper negative electrode current supply lead 23 is welded to the lower surface of the negative electrode current collector 21.
  • the negative electrode current supply lead 23 is welded to the battery can 60 at the bottom of the battery can 60.
  • the battery can 60 is formed, for example, of carbon steel with a thickness of 0.5 mm, and the surface is plated with nickel. By using such a material, the negative electrode current supply 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 welded to one end of the upper surface of the base portion 31 a of the positive electrode current collector 31 by welding.
  • the positive electrode conductive lead 33 is made possible to flow a large current by laminating and integrating a plurality of aluminum foils, and is given flexibility. That is, in order to flow a large current, it is necessary to increase the thickness of the connecting member, but if it is formed of a single metal plate, the rigidity is increased and the flexibility is impaired. Therefore, a large number of thin aluminum foils 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 laminating five aluminum foils each 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 an axial core 15 (see FIG. 1) at the center, and a positive electrode, a negative electrode and a separator are wound around the axial core 15. Then, the outermost first separator 13 is stopped by the adhesive tape 19.
  • the sealing lid 50 is provided with a cap 3 having an exhaust port 3c, a cap case 37 mounted on the cap 3 and having a cleavage groove 37a, a positive electrode connection plate 35 spot-welded to the back of a central portion of the cap case 37, a positive electrode connection plate It comprises an insulating ring 41 sandwiched between the peripheral upper surface of 35 and the back surface of the cap case 37, and is 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 disk-like peripheral portion 3a and a headless, bottomed cylindrical portion 3b projecting upward from the peripheral portion 3a, and has a hat-like shape as a whole.
  • An exhaust port 3c is formed at the center of the cylindrical portion 3b.
  • the cylindrical portion 3b functions as a positive electrode external terminal, and a bus bar or the like is connected.
  • the peripheral portion of the cap 3 is integrated by a folded flange 37 b of a cap case 37 formed of an aluminum alloy. That is, the peripheral edge of the cap case 37 is folded back along the upper surface of the cap 3 and the cap 3 is fixed by caulking.
  • the annular ring folded back on the upper surface of the cap 3, that is, the flange 37b and the cap 3 are friction welded and welded. That is, the cap case 37 and the cap 3 are integrated by caulking and fixing by the flange 37 b and welding.
  • the sealing lid 50 is provided with the flange 50F in which the cap case 37 and the cap 3 are integrated.
  • a circular cleavage groove 37a and a cleavage groove 37a radially extending in four directions from the circular cleavage groove 37a are formed.
  • the cleavage groove 37a is formed by pressing the upper surface side of the cap case 37 into a V-shape by a press and making the remaining portion thin.
  • the cleavage groove 37a is cleaved when the internal pressure in the battery can 60 rises to a predetermined value or more, and the decomposition gas inside is released.
  • the sealing lid 50 constitutes a current blocking mechanism.
  • a crack is generated in the cap case 37 in the cleavage groove 37a, and the inside decomposition gas is discharged from the exhaust port 3c of the cap 3. It is discharged and the pressure in the battery can 60 is reduced.
  • the cap case 37 called a cap case bulges out of 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 securing safety in the case of overcharging.
  • the safety against overcharge is improved by providing a sufficient capacity in the negative electrode even at the potential at which the gas generating agent reacts at the time of overcharge, but the details will be described. Will be described later.
  • the sealing lid 50 is placed on the upper cylindrical portion 31 c of the positive electrode current collecting member 31 in an insulating state. That is, the cap case 37 in which the cap 3 is integrated is mounted on the upper end surface of the positive electrode current collecting member 31 in an insulating state via the insulating ring 41. However, the cap case 37 is electrically connected to the positive electrode current collecting member 31 by the positive electrode conductive lead 33, and the cap 3 of the sealing lid 50 becomes the positive electrode of the battery 1.
  • the insulating ring 41 has an opening 41 a and a side 41 b projecting 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, has a substantially dish shape that is substantially uniform throughout substantially except for the central portion and bent to a slightly lower position on the central side.
  • the thickness of the connection plate 35 is, for example, about 1 mm.
  • a thin and dome-shaped protrusion 35 a is formed at the center of the connection plate 35, and a plurality of openings 35 b are formed around the protrusion 35 a.
  • the opening 35 b has a function of releasing the gas generated inside the battery.
  • the protrusion 35 a 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 assembly 10 is housed in the battery can 60, and the sealing lid 50, which is manufactured in advance 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 cylinder upper part.
  • the outer peripheral wall 43b of the gasket 43 is bent by a press or the like, and the sealing lid 50 is crimped so as to be pressed in the axial direction by the base 43a and the outer peripheral wall 43b. Thereby, the sealing lid 50 is fixed to the battery can 60 via the gasket 43.
  • the gasket 43 is initially formed on the peripheral side edge of the ring-shaped base portion 43a so that the outer peripheral wall portion 43b is substantially vertically erected upward, and the inner peripheral side is substantially downward from the base portion 43a It has a shape having a cylindrical portion 43c vertically suspended.
  • a predetermined amount of non-aqueous electrolytic solution is injected into the inside of the battery can 60.
  • the non-aqueous electrolytic solution it is preferable to use a solution in which a lithium salt is dissolved in a carbonate-based solvent.
  • lithium salts include lithium fluorophosphate (LiPF6), lithium fluoroborate (LiBF6), and the like.
  • the carbonate-based solvent 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, Can be mentioned.
  • FIG. 3 is a view showing a power generation unit of the cylindrical secondary battery 1.
  • the detail of the structure of the electrode group 10 is shown, and the perspective view of the state which 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 around the innermost periphery 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 outside It has been rolled up.
  • a first separator 13 and a second separator 14 are wound several turns inside the innermost negative electrode 12.
  • the outermost periphery is a negative electrode 12 and a first separator 13 wound around the outer periphery.
  • the positive electrode 11 is formed of aluminum foil and has a long shape, and includes a positive electrode sheet 11 a and a positive electrode processing portion in which a positive electrode mixture 11 b is applied to both surfaces of the positive electrode sheet 11 a.
  • the upper side edge along the longitudinal direction of the positive electrode sheet 11a is a positive electrode mixture non-treated portion 11c in which the positive electrode mixture 11b is not applied and the aluminum foil is exposed.
  • a large number of positive electrode leads 16 projecting upward in parallel with the shaft core 15 are integrally formed at equal intervals.
  • the positive electrode mixture 11 b is composed of a positive electrode active material, a positive electrode conductive agent, a positive electrode binder, and a positive electrode gas generating compound (gas generating agent).
  • the positive electrode conductive material is not limited as long as it can assist the transfer of electrons generated by the lithium storage and release reaction in the positive electrode mixture to the positive electrode.
  • the positive electrode conductive material include graphite and acetylene black.
  • the positive electrode binder can bind the positive electrode active material to the positive electrode conductive material and can bind the positive electrode mixture to the positive electrode current collector, unless it is significantly degraded by contact with the non-aqueous electrolyte.
  • the positive electrode binder include polyvinylidene fluoride (PVDF) and fluororubber.
  • Examples of the positive electrode gas generating compound include a carbonic acid inorganic compound, an oxalic acid inorganic compound, and a nitric acid inorganic compound which generate gas at the positive electrode potential in the overcharged state.
  • inorganic carbonated compounds are preferable, and examples thereof include lithium carbonate.
  • the method of forming the positive electrode mixture layer is not limited as long as the positive electrode mixture is formed on the positive electrode.
  • a method of applying a dispersion solution of the constituent material of the positive electrode mixture 11b on the positive electrode sheet 11a can be mentioned.
  • Examples of a method of applying the positive electrode mixture 11b to the positive electrode sheet 11a include a roll coating method, a slit die coating method, and the like. N-methyl pyrrolidone (NMP), water or the like is added to the positive electrode mixture 11b as a solvent example of the dispersion solution, and a kneaded slurry is uniformly coated on both sides of a 20 ⁇ m thick aluminum foil and dried. Press and cut. An example of the coating thickness of the positive electrode mixture 11 b is about 40 ⁇ m on one side. When cutting the positive electrode sheet 11a, the positive electrode lead 16 is integrally formed.
  • NMP N-methyl pyrrolidone
  • water or the like is added to the positive electrode mixture 11b as a solvent example of the dispersion solution, and a kneaded slurry is uniformly coated on both sides of a 20 ⁇ m thick aluminum foil and dried. Press and cut.
  • An example of the coating thickness of the positive electrode mixture 11 b is about 40 ⁇ m on
  • the negative electrode 12 is formed of a copper foil and has a long shape, and has a negative electrode sheet 12a and a negative electrode processing portion 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 12 a is a negative electrode mixture non-treated portion 12 c in which the negative electrode mixture 12 b is not applied and the copper foil is exposed.
  • a large number of negative electrode leads 17 extending in the opposite direction to the positive electrode lead 16 are integrally formed at equal intervals.
  • the negative electrode mixture 12 b is composed of a negative electrode active material, a negative electrode binder, and a thickener. By using graphite carbon as the negative electrode active material, a lithium ion secondary battery for a plug-in hybrid car or an electric car that requires a large capacity can be manufactured.
  • the method of forming the negative electrode mixture 12b is not limited as long as the negative electrode mixture 12b is formed on the negative electrode sheet 12a.
  • coating the negative mix 12b to the negative electrode sheet 12a the method of apply
  • a slurry obtained by adding N-methyl-2-pyrrolidone or water as a dispersion solvent to the negative electrode mixture 12b and kneading the mixture is used to form a rolled copper foil having a thickness of 10 ⁇ m. After applying uniformly on both sides and drying, it is pressed and cut.
  • An example of the coating thickness of the negative electrode mixture 12 b is about 40 ⁇ m on one side.
  • the width of the first separator 13 and the second separator 14 is WS
  • the width of the negative electrode mixture 12b formed on the negative electrode sheet 12a is WC
  • the width of the positive electrode mixture 11b formed on the positive electrode sheet 11a is WA
  • the width WC of the negative electrode mixture 12b is always larger than the width WA of the positive electrode mixture 11b. This is because in the case of a lithium ion secondary battery, lithium, which is a positive electrode active material, is ionized to permeate the separator, but when the negative electrode active material is not formed on the negative electrode side and the negative electrode sheet 12a is exposed, the negative electrode sheet It is because lithium precipitates on 12a and causes an internal short circuit.
  • FIG. 4 is an external perspective view of the prismatic secondary battery 100.
  • the prismatic secondary battery 100 includes a battery case including a battery can 101 and a battery cover 102.
  • the material of the battery can 101 and the battery cover 102 is aluminum or an aluminum alloy.
  • the battery can 101 is formed in a flat rectangular box shape whose one end is opened by deep drawing.
  • the battery can 101 has a rectangular flat 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.
  • FIG. 5 is an exploded perspective view of the prismatic secondary battery 100.
  • a wound electrode group 170 (see FIG. 6) is accommodated in the battery can 101.
  • 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 insulating sheet 108 a covering the central portion of the wound electrode group 170 and the insulating sheet 108 b covering the positive electrode uncoated portion of the wound electrode group 170 and the wound electrode group 170.
  • the material of the insulating sheets 108a, 108b and 108c is a resin having an insulating property such as polypropylene, and the battery can 101 and the wound electrode group 170 are electrically insulated.
  • the battery cover 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 cover 102 seals the opening of the battery can 101.
  • the battery lid 102 is provided with a positive electrode external terminal 104 and a negative electrode external terminal 105 electrically connected to the positive electrode 174 and the negative electrode 175 of the wound electrode group 170.
  • the positive electrode external terminal 104 is electrically connected to the positive electrode 174 (see FIG. 6) of the wound electrode group 170 via the current blocking mechanism 181 and the positive electrode current collector 180. Are electrically connected to the negative electrode 175 of the wound electrode group 170 via the negative electrode current collector 190. Therefore, power is supplied to the external device through the positive electrode external terminal 104 and the negative electrode external terminal 105, or externally generated power is supplied to the wound electrode group 170 through the positive electrode external terminal 104 and the negative electrode external terminal 105. Be charged.
  • a liquid injection hole 106 a for injecting an electrolytic solution into the battery case is formed in the battery cover 102.
  • the injection hole 106 a is sealed by the injection plug 106 b after the injection of the electrolyte.
  • the electrolytic solution for example, a non-aqueous electrolytic solution in which a lithium salt such as lithium hexafluorophosphate (LiPF6) 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 cover 102 by press processing.
  • the thin film member may be attached to the opening of the battery cover 102 by laser welding or the like, and the thin portion may be used as the gas discharge valve.
  • the gas discharge valve 103 generates heat by generating heat due to an abnormality such as an internal short circuit in the prismatic secondary battery 100, and when the pressure in the battery container rises and reaches a predetermined pressure, it is cleaved and the gas is generated from the inside By discharging, the pressure in the battery container is reduced.
  • the current interrupting mechanism 181 operates when the prismatic secondary battery 100 is overcharged and the positive electrode gas generating compound is decomposed by the positive electrode potential at that time to generate a decomposed gas and raise the internal pressure. Then, the electrical connection with the positive electrode external terminal 104 is cut off, and safety is ensured when the battery is overcharged.
  • the safety against overcharge is improved by providing a sufficient capacity in the negative electrode even at the potential at which the gas generating agent reacts at the time of overcharge, but the details will be described. Will be described later.
  • FIG. 6 is a perspective view showing a wound electrode group 170 of a square secondary battery.
  • FIG. 6 shows a state in which 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 the long positive electrode 174 and the negative electrode 175 in a flat shape around the winding central axis W with the separators 173a and 173b interposed. ing.
  • the positive electrode 174 is formed by forming a positive electrode mixture layer 176 on both surfaces of the positive electrode foil 171.
  • the positive electrode mixture is a mixture of a positive electrode active material, a positive electrode conductive agent, a binder (positive electrode binder), and a positive electrode gas generating compound.
  • the positive electrode gas generating compound include a carbonic acid inorganic compound, an oxalic acid inorganic compound, and a nitric acid inorganic compound that generate gas at the positive electrode potential in the overcharged state.
  • inorganic carbonated compounds are preferable, and examples thereof include lithium carbonate.
  • the negative electrode 175 has a negative electrode mixture layer 177 formed on both sides of the negative electrode foil 172.
  • the negative electrode mixture is a mixture of a negative electrode active material, a binder (negative electrode binder), and a thickener.
  • the positive electrode foil 171 is an aluminum foil having a thickness of about 20 to 30 ⁇ m
  • the negative electrode 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 absorbing and desorbing lithium ions.
  • the wound electrode group 170 In the width direction of the wound electrode group 170, that is, both ends in the direction of the wound central axis W orthogonal to the winding direction, one is a laminated portion of the positive electrode 174 and the other is a laminated portion of the negative electrode 175 There is.
  • the laminated portion of the positive electrode 174 provided at one end is obtained by laminating the positive uncoated portion on which the positive electrode mixture layer 176 is not formed, that is, the exposed portion of the positive electrode foil 171.
  • the laminated portion of the negative electrode 175 provided at the other end is obtained by laminating the uncoated portion of the negative electrode 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.
  • the above-described cylindrical secondary battery and prismatic secondary battery are sealed non-aqueous electrolyte secondary batteries.
  • the secondary battery comprises a positive electrode having a positive electrode mixture layer, a negative electrode having a negative electrode mixture layer, and a non-aqueous electrolyte to which a gas generating agent is added that generates a decomposition gas when the battery voltage exceeds a predetermined voltage.
  • a current blocking mechanism that is accommodated in the battery case and that operates when the pressure in the battery case rises with the generation of decomposition gas during overcharge.
  • Lithium carbonate is contained in the positive electrode as a gas generating agent.
  • the gas generating agent reacts at the time of overcharge, lithium is precipitated on the surface of the negative electrode
  • the separator may be broken, and the positive and negative electrodes may be short-circuited to damage the secondary battery.
  • the amount of the gas generating agent to be added is too small, the amount of gas generation at the time of overcharging may be small, and the current interruption mechanism may not operate properly.
  • too much emphasis is placed on the reliability of the current blocking mechanism, and if the gas generating agent is excessively added, the performance of the secondary battery is degraded. This is because the gas generating agent does not contribute to the charge / discharge reaction in the voltage range originally used, and becomes a resistance component of the secondary battery.
  • the overcharge negative electrode capacity is set larger than the overcharge capacity until the gas generating agent (positive electrode gas generating compound) reacts during overcharge and the current interruption mechanism operates.
  • the gas generating agent positive electrode gas generating compound
  • the secondary battery in the present embodiment does not add an excessive amount of the gas generating agent, because the negative electrode can sufficiently secure the charge capacity until the gas generating agent reacts and the current blocking mechanism operates. Does not reduce the performance of the secondary battery.
  • FIG. 7 is a graph showing the relationship between the potential and the capacity of the secondary battery in the present embodiment.
  • the vertical axis indicates the positive electrode and negative electrode potential (V) and the battery voltage (V) of the secondary battery
  • the horizontal axis indicates the capacity (mAh).
  • the dotted line indicated by a1 in FIG. 7 indicates the change of the negative electrode initial charge capacity Qnc, and the solid line indicated by a2 indicates the change of the negative electrode initial discharge capacity Qnd.
  • the change in negative electrode initial charge capacity Qnc shown in a1 in the figure gradually charges the negative electrode from less than 0% of SOC, further charges it more than 0% of SOC, and further charges it more than 100% of SOC to react the gas generating agent
  • the case where it charges until it exceeds electric potential is shown.
  • 0.2 C C is the capacity rate, and the relative ratio of the discharge current value to the battery capacity) until the potential with respect to lithium metal falls from 1.6 V to 0.005 V (negative charge termination voltage)
  • the negative electrode is set to a charge capacity exceeding the reaction potential of the gas generating agent.
  • the overcharge negative electrode capacity Qnoc of the negative electrode is set larger than the overcharge capacity Qcoc of the secondary battery.
  • the change in the negative electrode initial discharge capacity Qnd shown in a2 of FIG. 7 shows the case where the negative electrode is gradually discharged from the charge capacity exceeding the reaction potential of the gas generating agent to 100% SOC and discharged to SOC 0%. Specifically, constant current discharge is performed at a current of 0.2 C until the potential with respect to lithium metal becomes from 0.005 V to 1.6 V (discharge termination voltage of the negative electrode).
  • the negative electrode irreversible capacity Qnf is a capacity obtained by subtracting the initial capacity of the negative electrode first discharge capacity Qnd from the initial capacity of the negative electrode initial charge capacity Qnc.
  • the negative electrode irreversible capacity Qnf is a difference between the amount of electricity consumed for forming a solid. State interphase (SEI) film on the surface of the negative electrode at the time of initial charge and the amount of electricity trapped in the crystal structure and unable to be discharged.
  • SEI State interphase
  • the negative electrode reversible capacity Qnk is a capacity obtained by subtracting the negative electrode irreversible capacity Qnf from the capacity exceeding the reaction potential of the gas generating agent.
  • the charge termination voltage of the negative electrode is preferably 0.005 V or more and 0.010 V or less based on lithium metal.
  • the discharge termination voltage of the negative electrode is preferably 1.5 V or more and 1.6 V or less based on lithium metal.
  • the dotted line indicated by b1 in FIG. 7 represents a change in positive electrode initial charge capacity Qpc
  • the solid line indicated by b2 represents a change in positive electrode initial discharge capacity Qpd.
  • the change of the positive electrode initial charge capacity Qpc indicated by b1 in the figure indicates the case where the positive electrode is gradually charged from less than 0% of SOC, charged to more than 0% of SOC, and charged to a potential of 4.3V at 100% of SOC. Specifically, constant current charging is performed with a current of 0.2 C until the potential with respect to lithium metal becomes 4.3 V (positive electrode charge termination voltage) corresponding to 3.0 V to SOC 100%, and then 4.3 V After reaching a voltage of 2, charge for 2 hours with a constant voltage of 4.3V.
  • the dotted line indicates the case where the SOC is further charged up to 100% and charged to the reaction potential of 4.8 V of the gas generating agent.
  • the change of the positive electrode initial discharge capacity Qpd shown in b2 of FIG. 7 shows the case where the positive electrode is discharged from SOC 100% to less than SOC 0%. Specifically, constant current discharge is performed at a current of 0.2 C until the potential with respect to lithium metal becomes from 4.3 V to 3.0 V (the discharge final voltage of the positive electrode).
  • the positive electrode irreversible capacity Qpf is a capacity obtained by subtracting the initial capacity of the positive electrode first discharge capacity Qpd from the initial capacity of the positive electrode initial charge capacity Qpc.
  • the positive electrode irreversible capacity Qpf is generated due to the slow diffusion rate of lithium absorption into the crystal structure at the end of discharge.
  • the positive electrode reversible capacity Qpk is a capacity obtained by subtracting the positive electrode irreversible capacity Qpf from the capacity at SOC 100%.
  • the charge termination voltage of the positive electrode is preferably 4.2 V or more and 4.3 V or less based on lithium metal.
  • the discharge termination voltage of the positive electrode is preferably 2.5 V or more and 3.0 V or less based on lithium metal.
  • the solid line indicated by d1 in FIG. 7 represents the change of the battery capacity Qc.
  • the battery voltage is represented by the difference between the positive electrode potential and the negative electrode potential.
  • the battery capacity Qc indicates a capacity between SOC 0% and SOC 100%.
  • SOC means a state of charge where an upper limit voltage can be obtained within the range of reversibly chargeable and dischargeable operating voltage, that is, a fully charged state is SOC 100% and a state where a lower limit voltage is obtained is SOC 0% It shows the state of charge when.
  • secondary batteries are used between SOC 0% and SOC 100%.
  • the SOC 100% performs constant current charging at a current of 1 C until the battery voltage reaches 4.2 V (battery charge termination voltage), and then, after reaching a voltage of 4.2 V, charging for 2 hours at a constant voltage of 4.2 V It is in a state of SOC 0% is a state in which constant current discharge is performed at a current of 1 C until the battery voltage reaches 2.7 V (discharge final voltage of the battery).
  • the charge termination voltage of the secondary battery is a voltage that can be safely used without causing an excessive load on the secondary battery, and is preferably 4.1 V or more and 4.3 V or less.
  • the discharge end voltage of the secondary battery is preferably 2.5 V or more and 3.0 V or less.
  • the dotted line indicated by d2 in FIG. 7 indicates the overcharge area of the secondary battery.
  • Overcharging of the secondary battery refers to a state of charge of 100% or more of SOC.
  • the gas generating agent is decomposed, the internal pressure of the secondary battery is increased, and the current interrupting mechanism operates.
  • the capacity from SOC 100% to the voltage at which the gas generating agent reacts is referred to as overcharge capacity Qcoc of the secondary battery.
  • the overcharged negative electrode capacity Qnoc of the negative electrode is a capacity from 100% of SOC to when the negative electrode potential reaches 0.005V.
  • the overcharge negative electrode capacity Qnoc of the negative electrode is set larger than the overcharge capacity Qcoc of the secondary battery. If the overcharge negative electrode capacity Qnoc is smaller than the overcharge capacity Qcoc, lithium is deposited on the surface of the negative electrode before the current interrupting mechanism operates during overcharge, thereby separating the positive and negative electrodes. As a result, the positive and negative electrodes may be short-circuited, which may damage the secondary battery.
  • the positive electrode mixture includes the positive electrode active material, the positive electrode conductive material, the positive electrode binder, and the positive electrode gas generating compound.
  • the positive electrode active material is preferably lithium oxide. Examples thereof include lithium cobaltate, lithium manganate, lithium nickelate, lithium complex oxide (lithium oxide containing two or more types selected from cobalt, nickel and manganese) and the like. In this embodiment, lithium oxide containing cobalt, nickel and manganese was used.
  • a gas-generating compound it is preferable to add a gas-generating compound to the positive electrode mixture in order to ensure safety during overcharge.
  • the gas generating compound include a carbonic acid inorganic compound, a boric acid inorganic compound, and a nitric acid inorganic compound that generate gas at the positive electrode potential in the overcharged state.
  • inorganic carbonated compounds are preferable, and examples thereof include lithium carbonate.
  • lithium carbonate was contained in the positive electrode. Lithium carbonate reacts at a potential of 4.8 V or more with respect to lithium metal to generate gas.
  • the negative electrode mixture comprises the negative electrode active material, the negative electrode binder, and the thickener.
  • the negative electrode mixture may have a negative electrode conductive material such as acetylene black.
  • Graphite carbon is preferably used as the negative electrode active material.
  • the active material used for negative mix is used 1 type, or 2 or more types of these. In the present embodiment, natural graphite was used.
  • the secondary battery is composed of a positive electrode having a positive electrode capacity measured in the charge and discharge test shown in FIG. 7 and a negative electrode having a negative electrode capacity measured in the charge and discharge test shown in FIG.
  • the positive electrode initial charge capacity of the positive electrode active material is 175 mAh / g
  • the positive electrode initial charge capacity per unit area of the positive electrode coated with the positive electrode active material is 1.82 mAh / cm 2
  • the unit area of the positive electrode is The positive electrode reversible capacity per unit area is 1.60 mAh / cm 2
  • the positive electrode irreversible capacity per unit area of the positive electrode is 0.22 mAh / cm 2.
  • the negative electrode initial charge capacity of the negative electrode active material is 360 mAh / g, and the negative electrode initial charge capacity per unit area of the negative electrode coated with the negative electrode active material is 2.72 mAh / cm 2.
  • the negative electrode reversible capacity per unit area of the negative electrode is 2.45 mAh / cm 2, and the negative electrode irreversible capacity per unit area of the negative electrode is 0.27 mAh / cm 2.
  • the lithium ion secondary battery in the present embodiment is configured of such a positive electrode and a negative electrode.
  • the irreversible capacity per unit area of the negative electrode is larger than the irreversible capacity of the positive electrode, so when constant current discharge is performed at a current of 1 C until the battery voltage reaches 2.7 V. The reduction of the battery voltage is caused by the negative electrode.
  • the negative electrode is provided with a sufficient capacity even at the potential at which the gas generating agent reacts during overcharge. This improves the safety of the secondary battery against overcharging. Specifically, the capacity until the potential of the positive electrode exceeds the charge termination voltage of the secondary battery and reaches the reaction potential of the gas generating agent, and the potential of the negative electrode exceeds the charge termination voltage of the secondary battery and the charge termination of the negative electrode make it smaller than the capacity to reach the voltage. In other words, the ratio of the overcharged negative electrode capacity Qnoc to the overcharged negative electrode capacity Qcoc is 1.0 or more.
  • FIG. 8 is a graph showing the rate of increase in battery resistance of the secondary battery. Specifically, it is a diagram showing a rate of increase in battery resistance when the cycle test of the secondary battery is performed by changing the ratio (Qnk / Qc) of the negative electrode reversible capacity Qnk to the battery capacity Qc. In the cycle test, the secondary battery was repeatedly charged and discharged with constant current in a range from 30% SOC to 70% SOC in an environment of 25 ° C.
  • the battery resistance was measured by adjusting the battery voltage to 3.7 V in an environment of 25 ° C. of the secondary battery. First, after charging to 3.7 V with a constant current of 1 C, charging was performed with a constant voltage for 2 hours, and then discharging was performed with a current of 60 A, and the battery resistance after 10 seconds was determined. The battery resistance was determined by dividing the difference between the voltage before current application and the voltage after 10 seconds by the applied current. The rate of increase of battery resistance is the ratio of battery resistance before and after the cycle test. The battery resistance was measured daily, and a cycle test was performed until the rate of increase in battery resistance reached 130%.
  • the horizontal axis in FIG. 8 is the ratio (Qnk / Qc) of the negative electrode reversible capacity Qnk to the battery capacity Qc, and the vertical axis is the number of cycles until the battery resistance increase rate reaches 130% (days).
  • the cycle days were plotted in the graph according to the ratio (Qnk / Qc) of the negative electrode reversible capacity Qnk to the battery capacity Qc of the secondary battery.
  • the cycle characteristic of the secondary battery is better as the ratio of the negative electrode reversible capacity Qnk to the battery capacity Qc is higher. This is because the mass of the negative electrode active material accompanied by charge and discharge reaction in the voltage range usually used is increased, so the current load on the electrode is reduced and the cycle characteristics are improved without adding the gas generating agent excessively. It is because
  • the ratio is 1.5 or more, taking a margin.
  • the secondary battery includes a positive electrode including a positive electrode mixture layer, a negative electrode including a negative electrode mixture layer, and a gas generating agent that generates a decomposition gas when the battery voltage exceeds a predetermined voltage.
  • the non-aqueous electrolyte as described above is accommodated in the battery case, and is provided with a current interrupting mechanism that operates when the pressure in the battery case rises with the generation of the decomposition gas at the time of overcharging.
  • Lithium carbonate is contained in the positive electrode as a gas generating agent.
  • FIG. 9 is a graph showing the relationship between the potential and the capacity of the secondary battery in the present embodiment.
  • the vertical axis represents the positive and negative electrode potentials of the secondary battery and the battery voltage (V), and the horizontal axis represents the capacity (mAh).
  • the relationship between the potential and the capacity of the secondary battery shown in FIG. 9 in the present embodiment shows characteristics when the positive electrode irreversible capacity Qpf is larger than the negative electrode irreversible capacity Qnf.
  • the dotted line indicated by a3 in FIG. 9 represents the change in the negative electrode initial charge capacity Qnc, and the solid line indicated by a4 represents the change in the negative electrode initial discharge capacity Qnd.
  • the dotted line indicated by b3 in FIG. 9 represents the change in the positive electrode initial charge capacity Qpc, and the solid line indicated by b4 represents the change in the positive electrode initial discharge capacity Qpd.
  • the solid line indicated by d3 in FIG. 9 represents the change of the battery capacity Qc.
  • the dotted line indicated by d4 in FIG. 9 indicates the overcharge area of the secondary battery.
  • the change in negative electrode initial charge capacity Qnc shown in a3 in the figure gradually charges the negative electrode from less than 0% of SOC, further charges it more than 0% of SOC, and further charges it more than 100% of SOC, the reaction of the gas generating agent
  • the case where it charges until it exceeds electric potential is shown.
  • constant current charging is performed at a current of 0.2 C until the potential with respect to lithium metal becomes from 1.6 V to 0.005 V (the charge termination voltage of the negative electrode), and after reaching a voltage of 0.005 V , Charge for 2 hours with a constant voltage of 0.005V.
  • the negative electrode is set to a charge capacity exceeding the reaction potential of the gas generating agent.
  • the overcharge negative electrode capacity Qnoc is set larger than the overcharge capacity Qcoc.
  • the change of the negative electrode initial discharge capacity Qnd shown in a4 of FIG. 9 shows a case where the negative electrode is gradually discharged from the charge capacity exceeding the reaction potential of the gas generating agent to 100% SOC and discharged to SOC 0% (less than). Specifically, constant current discharge is performed at a current of 0.2 C until the potential with respect to lithium metal becomes from 0.005 V to 1.6 V (discharge termination voltage of the negative electrode).
  • the negative electrode irreversible capacity Qnf is a capacity obtained by subtracting the initial capacity of the negative electrode first discharge capacity Qnd from the initial capacity of the negative electrode initial charge capacity Qnc.
  • the negative electrode reversible capacity Qnk is a capacity obtained by subtracting the negative electrode irreversible capacity Qnf from the capacity exceeding the reaction potential of the gas generating agent.
  • the charge termination voltage of the negative electrode is preferably 0.005 V or more and 0.010 V or less based on lithium metal.
  • the discharge termination voltage of the negative electrode is preferably 1.5 V or more and 1.6 V or less based on lithium metal.
  • the dotted line indicated by b3 in FIG. 9 represents the change in the positive electrode initial charge capacity Qpc
  • the solid line indicated by b4 represents the change in the positive electrode initial discharge capacity Qpd.
  • the change in the positive electrode initial charge capacity Qpc indicated by b3 in the figure indicates the case where the positive electrode is gradually charged from less than 0% of SOC, charged to more than 0% of SOC, and charged to a potential of 4.3V at 100% of SOC. Specifically, constant current charging is performed with a current of 0.2 C until the potential with respect to lithium metal becomes 4.3 V (positive electrode charge termination voltage) corresponding to 3.0 V to SOC 100%, and then 4.3 V After reaching a voltage of 2, charge for 2 hours with a constant voltage of 4.3V.
  • the dotted line indicates the case where the SOC is further charged up to 100% and charged to the reaction potential of 4.8 V of the gas generating agent.
  • the change of the positive electrode initial discharge capacity Qpd indicated by b4 in FIG. 9 shows the case where the positive electrode is discharged from SOC 100% to SOC 0%. Specifically, constant current discharge is performed at a current of 0.2 C until the potential with respect to lithium metal becomes from 4.3 V to 3.0 V (the discharge final voltage of the positive electrode).
  • the positive electrode irreversible capacity Qpf is a capacity obtained by subtracting the initial capacity of the positive electrode first discharge capacity Qpd from the initial capacity of the positive electrode initial charge capacity Qpc.
  • the positive electrode reversible capacity Qpk is a capacity obtained by subtracting the positive electrode irreversible capacity Qpf from the capacity at SOC 100%.
  • the charge termination voltage of the positive electrode is preferably 4.2 V or more and 4.3 V or less based on lithium metal.
  • the discharge termination voltage of the positive electrode is preferably 2.5 V or more and 3.0 V or less based on lithium metal.
  • the solid line indicated by d3 in FIG. 9 represents the change of the battery capacity Qc.
  • the battery voltage is represented by the difference between the positive electrode potential and the negative electrode potential.
  • the battery capacity Qc indicates a capacity between SOC 0% and SOC 100%.
  • the SOC 100% performs constant current charging at a current of 1 C until the battery voltage reaches 4.2 V (battery charge termination voltage), and then, after reaching a voltage of 4.2 V, charging for 2 hours at a constant voltage of 4.2 V It is in a state of SOC 0% is a state in which constant current discharge is performed at a current of 1 C until the battery voltage reaches 2.7 V (discharge final voltage of the battery).
  • the charge termination voltage of the secondary battery is a voltage that can be safely used without causing an excessive load on the secondary battery, and is preferably 4.1 V or more and 4.3 V or less.
  • the discharge end voltage of the secondary battery is preferably 2.5 V or more and 3.0 V or less.
  • the dotted line indicated by d4 in FIG. 9 indicates the overcharge area of the secondary battery.
  • Overcharging of the secondary battery refers to a state of charge of 100% or more of SOC.
  • the gas generating agent is decomposed, the internal pressure of the secondary battery is increased, and the current interrupting mechanism operates.
  • the capacity from SOC 100% to the voltage at which the gas generating agent reacts is referred to as overcharge capacity Qcoc.
  • the overcharged negative electrode capacity Qnoc of the negative electrode is a capacity from 100% of SOC to when the negative electrode potential reaches 0.005V.
  • the overcharge negative electrode capacity Qnoc of the negative electrode is set larger than the overcharge capacity Qcoc of the secondary battery.
  • the positive electrode reversible capacity Qpk which is the capacity until the potential of the positive electrode reaches the charge termination voltage of the secondary battery, and the charge termination voltage of the secondary battery, until the potential of the positive electrode reaches the reaction potential of the gas generating agent
  • the sum with the overcharge capacity Qcoc which is the capacity of the above, is set smaller than the negative electrode reversible capacity Qnk of the negative electrode.
  • the positive electrode mixture and the negative electrode mixture are the same as those described in the first embodiment, and thus the description thereof is omitted.
  • capacitance of the positive electrode of the lithium ion secondary battery in this embodiment and a negative electrode is demonstrated.
  • the secondary battery is composed of a positive electrode having a positive electrode capacity measured in the charge and discharge test shown in FIG. 9 and a negative electrode having a negative electrode capacity measured in the charge and discharge test shown in FIG.
  • the positive electrode initial charge capacity of the positive electrode active material is 180 mAh / g
  • the positive electrode initial charge capacity per unit area of the positive electrode coated with the positive electrode active material is 1.87 mAh / cm 2
  • the unit area of the positive electrode is The positive electrode reversible capacity per unit area is 1.59 mAh / cm 2
  • the positive electrode irreversible capacity per unit area of the positive electrode is 0.28 mAh / cm 2.
  • the negative electrode initial charge capacity of the negative electrode active material is 365 mAh / g, and the negative electrode initial charge capacity per unit area of the negative electrode coated with the negative electrode active material is 2.75 mAh / cm 2.
  • the negative electrode reversible capacity per unit area of the negative electrode is 2.48 mAh / cm 2, and the negative electrode irreversible capacity per unit area of the negative electrode is 0.27 mAh / cm 2.
  • the lithium ion secondary battery in the present embodiment is configured of such a positive electrode and a negative electrode.
  • the irreversible capacity per unit area of the positive electrode is larger than the irreversible capacity of the negative electrode, constant current discharge at a current of 1 C until the battery voltage becomes 2.7 V The reduction of the battery voltage is caused by the positive electrode.
  • the safety of the secondary battery against overcharge can be improved by providing a sufficient capacity in the negative electrode even at the potential at which the gas generating agent reacts at the time of overcharge.
  • the internal pressure of the battery container 60 containing the positive electrode having the positive electrode mixture, the negative electrode having the negative electrode mixture, the positive electrode and the negative electrode, and the battery container 60 has a predetermined operating pressure.
  • a current blocking mechanism 181 for blocking the current flowing between the positive electrode and the negative electrode, and the positive electrode mixture contains a gas generating agent, and the potential of the positive electrode is the charge termination voltage of the secondary battery 1, 100.
  • the capacity until the reaction potential of the gas generating agent is reached is smaller than the capacity until the potential of the negative electrode exceeds the charge termination voltage of the secondary battery 1, 100 to reach the charge termination voltage of the negative electrode.
  • the reaction potential of the gas generating agent in the secondary batteries 1 and 100 is 4.8 V to 5.0 V. Thereby, a secondary battery excellent in safety against overcharge can be provided.
  • the gas generating agent in the secondary battery 1, 100 is lithium carbonate.
  • lithium carbonate in the positive electrode As a gas generating agent, it is possible to provide a secondary battery excellent in safety against overcharge.
  • the negative electrode active material of the negative electrode in the secondary batteries 1 and 100 is one or more of natural graphite, artificial graphite, non-graphitizable carbon, graphitizable carbon, and silicon oxide mixed. This improves the safety of the secondary battery against overcharging.
  • the charge termination voltage of the negative electrode in the secondary battery 1, 100 is in the range of 0.01 V to 0.005 V. This improves the safety of the secondary battery against overcharging.
  • the secondary battery 1, 100 has a capacity until the potential of the positive electrode reaches the charge termination voltage of the secondary battery 1, 100 and the charge termination voltage of the secondary battery 1, 100.
  • the sum of the capacity of the gas generating agent until reaching the reaction potential is smaller than the reversible capacity of the negative electrode.
  • the negative electrode can sufficiently receive the charge capacity until the gas generating agent decomposes and the current blocking mechanism reacts, so it is not necessary to add the gas generating agent in excess.
  • the ratio of the reversible capacity of the negative electrode to the battery capacity of the secondary batteries 1 and 100 is 1.5 or more.
  • the positive electrode first charge capacity per unit area of the positive electrode coated with the positive electrode active material is 1.82 mAh / cm 2
  • the positive electrode reversible capacity per unit area of the positive electrode is 1.60 mAh /
  • the positive electrode irreversible capacity per unit area of the positive electrode is 0.22 mAh / cm 2
  • the negative electrode of the secondary battery has a negative electrode initial charge capacity of 2.72 mAh / cm 2 per unit area of the negative electrode coated with the negative electrode active material, and a negative electrode reversible capacity of 2.45 mAh / cm 2 per unit area of the negative electrode.
  • the negative electrode irreversible capacity per unit area of the negative electrode is 0.27 mAh / cm 2.
  • the positive electrode of the secondary battery has a first charge capacity per unit area of the positive electrode coated with the positive electrode active material of 1.87 mAh / cm 2 and a reversible capacity per unit area of the positive electrode of 1.59 mAh / and the positive electrode irreversible capacity per unit area of the positive electrode is 0.28 mAh / cm 2, and
  • the negative electrode of the secondary battery has an initial negative charge capacity per unit area of the negative electrode coated with the negative electrode active material of 2.75 mAh / cm 2, and a negative electrode reversible capacity per unit area of the negative electrode of 2.48 mAh / cm 2
  • the negative electrode irreversible capacity per unit area of the negative electrode is 0.27 mAh / cm 2.
  • the negative electrode can sufficiently receive the charge capacity until the gas generating agent decomposes and the current blocking mechanism reacts, so it is not necessary to add the gas generating agent in excess.

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  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
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  • Inorganic Chemistry (AREA)
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Abstract

Si la capacité de charge d'une électrode négative est faible, il existe un risque que le lithium précipite sur la surface de l'électrode négative et rompe le séparateur qui divise les électrodes positives et négatives, ce qui provoque un court-circuit entre les électrodes positive et négative, endommageant ainsi la batterie rechargeable. La batterie rechargeable (1, 100) selon l'invention comprend : une électrode positive ayant un mélange d'électrode positive; une électrode négative ayant un mélange d'électrode négative; un contenant de batterie (60) pour recevoir l'électrode positive et l'électrode négative; et un mécanisme de coupure de courant (181) qui coupe le courant circulant entre l'électrode positive et l'électrode négative lorsque la pression interne du contenant de batterie (60) a atteint une pression de travail prescrite. Le mélange d'électrode positive contient un agent générateur de gaz. La capacité qui porte une augmentation du potentiel de l'électrode positive, de la tension de fin de charge de la batterie rechargeable (1, 100) au potentiel qui déclenche la réaction de l'agent générateur de gaz, est conçue de sorte à être inférieure à la capacité qui porte une augmentation du potentiel de l'électrode négative, de la tension de fin de charge de la batterie rechargeable (1, 100) à la tension de fin de charge de l'électrode négative.
PCT/JP2018/041908 2017-12-04 2018-11-13 Batterie rechargeable WO2019111644A1 (fr)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021020290A1 (fr) * 2019-08-01 2021-02-04 株式会社Ｇｓユアサ Élément de stockage d'énergie à électrolyte non aqueux, son procédé de fabrication et dispositif de stockage d'énergie

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10134817A (ja) * 1996-10-28 1998-05-22 Shin Kobe Electric Mach Co Ltd 有機電解液二次電池
JP2000306610A (ja) * 1999-04-21 2000-11-02 Japan Storage Battery Co Ltd 非水電解質二次電池
JP2015011930A (ja) * 2013-07-01 2015-01-19 トヨタ自動車株式会社 非水電解質二次電池

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10134817A (ja) * 1996-10-28 1998-05-22 Shin Kobe Electric Mach Co Ltd 有機電解液二次電池
JP2000306610A (ja) * 1999-04-21 2000-11-02 Japan Storage Battery Co Ltd 非水電解質二次電池
JP2015011930A (ja) * 2013-07-01 2015-01-19 トヨタ自動車株式会社 非水電解質二次電池

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021020290A1 (fr) * 2019-08-01 2021-02-04 株式会社Ｇｓユアサ Élément de stockage d'énergie à électrolyte non aqueux, son procédé de fabrication et dispositif de stockage d'énergie

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