WO2022209506A1 - リチウム二次電池用負極活物質、金属負極及びリチウム二次電池 - Google Patents

リチウム二次電池用負極活物質、金属負極及びリチウム二次電池 Download PDF

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WO2022209506A1
WO2022209506A1 PCT/JP2022/008136 JP2022008136W WO2022209506A1 WO 2022209506 A1 WO2022209506 A1 WO 2022209506A1 JP 2022008136 W JP2022008136 W JP 2022008136W WO 2022209506 A1 WO2022209506 A1 WO 2022209506A1
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aluminum
negative electrode
active material
mass
electrode active
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English (en)
French (fr)
Japanese (ja)
Inventor
俊昭 熊谷
慎吾 松本
祥晃 本多
祥史 松尾
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Sumitomo Chemical Co Ltd
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Sumitomo Chemical Co Ltd
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Priority to US18/550,579 priority Critical patent/US20240170658A1/en
Priority to CN202280023734.4A priority patent/CN117043988A/zh
Priority to JP2023510685A priority patent/JPWO2022209506A1/ja
Priority to EP22779731.3A priority patent/EP4317499A1/en
Publication of WO2022209506A1 publication Critical patent/WO2022209506A1/ja
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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
    • H01M4/134—Electrodes based on metals, Si or alloys
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B35/00—Boron; Compounds thereof
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C21/00—Alloys based on aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
    • 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
    • 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
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/46—Alloys based on magnesium or aluminium
    • H01M4/463—Aluminium based
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/40—Electric properties
    • 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
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • 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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • 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 negative electrode active material for lithium secondary batteries, a metal negative electrode, and a lithium secondary battery.
  • Graphite is conventionally used as a negative electrode material for rechargeable secondary batteries.
  • studies have been made to improve the battery performance by using a material having a larger theoretical capacity than graphite.
  • metallic materials capable of intercalating and deintercalating lithium ions have attracted attention.
  • a negative electrode made of a metal material may be referred to as a "metal negative electrode”.
  • Patent Document 1 describes a non-aqueous electrolyte battery using a clad material as a metal negative electrode, in which a substrate layer that does not alloy with lithium and an aluminum layer that forms an alloy with lithium are joined.
  • a metal negative electrode made of aluminum has a larger theoretical capacity than a graphite negative electrode, but has the problem that cycle characteristics tend to deteriorate.
  • lithium secondary batteries are required to have further improved cycle characteristics.
  • the present invention has been made in view of such circumstances, and provides a negative electrode active material for a lithium secondary battery, a metal negative electrode, and a lithium secondary battery that can improve the cycle characteristics of the lithium secondary battery. With the goal.
  • the present invention includes the following [1] to [11].
  • a negative electrode active material for a lithium secondary battery that satisfies the following (1) and (2) in an image obtained by the method described in the image acquisition conditions below, or including both. (Image acquisition conditions)
  • the negative electrode active material for a lithium secondary battery is rolled in one direction to obtain a foil having a thickness of 50 ⁇ m.
  • the foil is cut in a plane parallel to the rolling direction and perpendicular to the rolling surface to obtain a cross section.
  • the cross section is measured by a backscattered electron diffraction method to obtain an image of crystal grains of metal crystals constituting the aluminum phase.
  • the area-weighted average grain diameter of the equivalent circle diameter of the crystal grains is 4.5 ⁇ m or less.
  • the aspect ratio of the crystal grains has an arithmetic mean value of more than 1.6 and a standard deviation of 0.9 or less.
  • An aluminum-containing metal in which a non-aluminum phase is dispersed in an aluminum phase, the non-aluminum phase contains B and Ti, and the content of the non-aluminum phase with respect to the total amount of the aluminum phase and the non-aluminum phase A negative electrode active material for a lithium secondary battery, wherein the ratio is 0.001% by mass or more and 5% by mass or less.
  • the aluminum-containing metal is composed of Al, Ti, B, element X and unavoidable impurities, and the content of Ti with respect to the total mass of the aluminum-containing metal is 10 mass ppm or more and 1000 mass ppm or less, and The content of B with respect to the total mass of the aluminum-containing metal is 2 mass ppm or more and 200 mass ppm or less, and the element X is selected from the group consisting of Si, Ge, Sn, Ag, Sb, Bi and In.
  • the lithium secondary according to any one of [1] to [3], wherein the content of the unavoidable impurity relative to the total amount of the aluminum-containing metal is 0.1% by mass or less, which is one or more elements.
  • Negative electrode active material for batteries is composed of Al, Ti, B, element X and unavoidable impurities, and the content of Ti with respect to the total mass of the aluminum-containing metal is 10 mass ppm or more and 1000 mass ppm or less, and The content of B with respect to the total mass
  • the impurity elements contained in the inevitable impurities are one or more elements selected from the group consisting of Cu, Mn, Ni and V, and the total content of the impurity elements with respect to the total mass of the aluminum-containing metal is
  • negative electrode active material A metal negative electrode comprising the negative electrode active material for a lithium secondary battery according to any one of [1] to [7] and capable of intercalating and deintercalating lithium ions.
  • a metal negative electrode for a lithium secondary battery comprising a clad material having a negative electrode active material layer made of the negative electrode active material for a lithium secondary battery described in [8] and a collector layer.
  • the metal negative electrode according to any one of [8] to [10] a positive electrode capable of intercalating and deintercalating lithium ions, and an electrolyte disposed between the metal negative electrode and the positive electrode. , a lithium secondary battery.
  • the present invention it is possible to provide a negative electrode active material for a lithium secondary battery, a metal negative electrode, and a lithium secondary battery that can improve the cycle characteristics of the lithium secondary battery.
  • FIG. 1 is a schematic diagram showing an example of a lithium secondary battery
  • FIG. 1 is a schematic diagram showing an example of an all-solid lithium secondary battery
  • the negative electrode active material of the present embodiment is an aluminum-containing metal and is a rolled material rolled in one direction.
  • Aluminum-containing metals have non-aluminum phases dispersed in an aluminum phase.
  • the aluminum-containing metal as the negative electrode active material is capable of intercalating and deintercalating lithium ions.
  • the aluminum phase is a phase containing aluminum and additional elements and impurities dissolved in aluminum crystals.
  • the aluminum forming the aluminum phase is preferably high-purity aluminum.
  • High-purity aluminum is aluminum with a purity of 99% by mass or more. High-purity aluminum will be described later.
  • non-aluminum phase The non-aluminum phase exists dispersedly in the aluminum phase.
  • a non-aluminum phase exists dispersedly in an aluminum phase means a state in which a particulate non-aluminum phase exists in an aluminum phase.
  • Elements other than aluminum are B and Ti.
  • the element X may be included as an element other than aluminum.
  • Element X is one or more elements selected from the group consisting of Si, Ge, Sn, Ag, Sb, Bi and In.
  • pill is an expression that expresses how the non-aluminum phase aggregates and looks like particles when the surface or cross section of the aluminum-containing metal is observed.
  • the content of the non-aluminum phase with respect to the total amount of the aluminum phase and the non-aluminum phase preferably satisfies 0.001% by mass or more and 5% by mass or less.
  • An aluminum-containing metal having a non-aluminum phase content of not more than the above upper limit contains few impurities other than aluminum, so that the cycle characteristics are less likely to deteriorate.
  • An aluminum-containing metal having a non-aluminum phase content of at least the above lower limit is likely to have the effect of crystal refinement, which will be described later.
  • composition analysis The composition of the negative electrode active material can be confirmed by an inductive coupled plasma (ICP) analysis method. For example, it can be measured using an ICP emission spectrometer (SII Nanotechnology Co., Ltd., SPS3000).
  • ICP inductive coupled plasma
  • the negative electrode active material absorbs lithium ions during charging and releases lithium ions during discharging.
  • the negative electrode active material expands when absorbing lithium ions, and contracts when releasing lithium ions.
  • Aluminum-containing metals have a very large lithium ion storage capacity. Therefore, the aluminum-containing metal undergoes a large volume expansion when lithium is inserted and a large volume contraction when lithium is desorbed. If the expansion and contraction cause distortion or stress concentration, the metal negative electrode develops into cracks, which shortens the cycle life.
  • the present invention relates to the technical idea that the cycle characteristics of a lithium secondary battery can be improved when the crystal grains of the metal crystals constituting the aluminum phase are small and the orientation direction of the crystal grains satisfies predetermined requirements. . This point will be explained.
  • the negative electrode active material satisfies (1) and (2) described later when grains of multiple metal crystals forming the aluminum phase are observed in an image obtained by the method described in the image acquisition conditions below.
  • a foil 40 having a thickness of 50 ⁇ m is obtained by rolling the negative electrode active material in one direction.
  • Reference R1 indicates the rolling direction.
  • the obtained foil 40 is cut along a rough surface S0 parallel to the rolling direction R1 and perpendicular to the upper surface S2 of the foil 40 to obtain a cross section S1.
  • the cross section S1 is measured by an Electron Back Scattered Diffraction Pattern (EBSD) method to obtain an image of metal crystal grains that constitute the aluminum phase.
  • EBSD Electron Back Scattered Diffraction Pattern
  • the negative electrode active material is a plate-like member.
  • Plate-like means a three-dimensional shape having at least two opposing planes (an upper surface S2 and a mask surface S3). In the plate-like negative electrode active material, the distance between two opposing planes corresponds to the thickness of the negative electrode active material.
  • the thickness of the negative electrode active material is, for example, 5 ⁇ m or more and 200 ⁇ m or less.
  • the thickness of the negative electrode active material to be measured is less than 50 ⁇ m
  • a plurality of sheets of the negative electrode active material are laminated to obtain a foil with a thickness of 50 ⁇ m.
  • the obtained foil 40 is cut along the rough surface S0 parallel to the rolling direction R1 and perpendicular to the upper surface S2 of the foil 40 to obtain a cross section.
  • An argon ion milling device for example, can be used for processing to obtain the cross section of the foil 40 .
  • An example of processing conditions is described below.
  • Argon ion milling device IB-19520CCP (manufactured by JEOL Ltd.) Accelerating voltage: 6 kV Atmosphere: Air Temperature: -100°C
  • the cross section S1 of the foil is measured by the EBSD method.
  • the EBSD method is widely used as a technique for analyzing the orientation distribution of crystal texture.
  • the EBSD method is typically performed using a scanning electron microscope equipped with a backscattered electron diffraction detector.
  • JSM-7900F manufactured by JEOL Ltd. can be used as a scanning electron microscope.
  • a backscattered electron diffraction detector for example, Symmetry manufactured by Oxford Instruments Co., Ltd. can be used.
  • the cross section S1 of the foil is scanned with an electron beam, and the diffraction pattern of the backscattered electrons is read with a device.
  • the diffraction pattern of backscattered electrons read into the apparatus is input into a computer, and the sample surface is scanned while performing crystal orientation analysis using analysis software AZtec attached to Symmetry.
  • the crystal is indexed at each measurement point, and the crystal orientation at each measurement point is obtained.
  • a region having the same crystal orientation is defined as one crystal grain, and a mapping image of the distribution of crystal grains, that is, a grain map is obtained.
  • a mapping image of the distribution of crystal grains that is, a grain map is obtained.
  • scanning is repeated until the number of crystal grains reaches 10000 or more and 12000 or less.
  • the pixel size of the crystal orientation map obtained by EBSD measurement is preferably 0.05 ⁇ m per side.
  • the area-weighted average grain diameter of the equivalent circle diameter of the crystal grains is 4.5 ⁇ m or less.
  • the area-weighted average particle size is preferably 4.0 ⁇ m or less, more preferably 3.5 ⁇ m or less.
  • the area-weighted average grain size is equal to or less than the above upper limit value, in other words, when the crystal grain size is small, grain boundaries tend to increase. Since stress is relieved at grain boundaries during expansion and contraction, the use of a negative electrode active material that satisfies (1) makes it difficult for cycle characteristics to deteriorate.
  • the area-weighted average particle size is, for example, 0.1 ⁇ m or more, 0.5 ⁇ m or more, or 1.0 ⁇ m or more.
  • the area-weighted average particle diameter is at least the above lower limit, lithium can be sufficiently occluded.
  • the upper limit and lower limit of the area-weighted average particle size can be combined arbitrarily. Examples of combinations include area-weighted average particle diameters of 0.1 ⁇ m to 4.5 ⁇ m, 0.5 ⁇ m to 4.0 ⁇ m, and 1.0 ⁇ m to 3.5 ⁇ m.
  • FIG. 2 shows a schematic diagram of an example of the cross section S1.
  • Crystal grains 41 can be confirmed by observing the cross section S1. Let a be the direction perpendicular to the upper surface S2 of the foil, and b be the direction parallel to it.
  • cross section S1 crystal grain 41 is observed as a flat shape having a major axis in the b direction. The major axis and minor axis of the crystal grain 41 are automatically measured by analysis software AZtec attached to Symmetry.
  • the average value of the ratio of the major axis to the minor axis (long axis/short axis) of the crystal grains exceeds 1.6, preferably 1.7 or more, and more preferably 1.85 or more.
  • the crystal grains tend to flatten in a direction parallel to the upper surface S2.
  • the directions of expansion and contraction during charging and discharging are likely to be aligned in the vertical direction with respect to the upper surface S2.
  • the directions of expansion and contraction tend to be aligned, so cracks are less likely to occur, and the cycle characteristics of the lithium secondary battery can be improved.
  • the upper limit of the aspect ratio is, for example, 2.5 or less, 2.4 or less, or 2.3 or less.
  • the above upper limit and lower limit of the aspect ratio can be combined arbitrarily. Examples of combinations include more than 1.6 and 2.5 or less, 1.7 or more and 2.4 or less, and 1.85 or more and 2.3 or less.
  • the dispersed state of the non-aluminum phase in the aluminum phase can be grasped, for example, by observing the cross section of the aluminum-containing metal foil having a thickness of 0.5 mm.
  • the aluminum-containing metal foil is cut and the cross section is etched with an aqueous sodium hydroxide solution.
  • the cross section exposes recesses corresponding to the non-aluminum phase.
  • a SEM image (magnification of 300 times) and a metal microscope image (magnification of 300 times) are acquired for the cross section after etching. Considering that one recess corresponds to one particle (one non-aluminum phase), the particle diameter and the number of particles exposed in the cross section are measured.
  • a negative electrode active material of one aspect of the present embodiment is an aluminum-containing metal in which a non-aluminum phase is dispersed in an aluminum phase.
  • the non-aluminum phase contains B and Ti.
  • the content of the non-aluminum phase is 0.001% by mass or more and 5% by mass or less with respect to the total amount of the aluminum phase and the non-aluminum phase.
  • the confirmation method of the dispersion state of the non-aluminum phase and the composition analysis method are the same as those described above.
  • the grains of the metal crystals forming the aluminum phase tend to be small. Crystal grain boundaries tend to increase in such a negative electrode active material. Since stress is relieved at grain boundaries during expansion and contraction due to charging and discharging, cycle characteristics of a lithium secondary battery using such a negative electrode active material are less likely to deteriorate.
  • the aluminum-containing metal preferably consists of Al, Ti, B, element X and inevitable impurities.
  • Element X is one or more elements selected from the group consisting of Si, Ge, Sn, Ag, Sb, Bi and In.
  • the content of Ti with respect to the total mass of the aluminum-containing metal preferably satisfies 10 mass ppm or more and 1000 mass ppm or less, and the content of B with respect to the total mass of the aluminum-containing metal is 2 mass ppm or more and 200 mass ppm. It is preferable to satisfy the following.
  • titanium boron, aluminum titanium boron, titanium alone, aluminum titanium, boron alone, or aluminum boron is added as a raw material for refining aluminum crystals. Therefore, one or both of Ti and B remain as raw material residue.
  • the Ti content is equal to or higher than the above lower limit, it becomes easier to obtain the effect of crystal refinement. Further, when the Ti content is equal to or less than the above upper limit, the proportion of the non-aluminum phase is suppressed to a certain proportion or less, and the battery characteristics are less likely to deteriorate.
  • the content of the element X with respect to the total amount of the aluminum-containing metal preferably satisfies 0.1% by mass or more and 4.0% by mass or less.
  • Element X is a material capable of intercalating and deintercalating lithium ions.
  • a lithium secondary battery using a negative electrode active material in which the content of the element X satisfies the above range is less likely to deteriorate in cycle characteristics.
  • the element X is preferably Si.
  • the Si content with respect to the total amount of the aluminum-containing metal preferably satisfies 0.1% by mass or more and 4.0% by mass or less.
  • a lithium secondary battery using a negative electrode active material having a Si content that satisfies the above range is unlikely to deteriorate in cycle characteristics.
  • Inevitable impurities can cause a decrease in electrical conductivity, a decrease in the strength of the negative electrode active material, and the like.
  • Such unavoidable impurities include production residues that are inevitably mixed in the refining process, and the unavoidable impurities tend to remain in the range of 0.1% by mass or less.
  • the total amount of inevitable impurities with respect to the total amount of aluminum-containing metal is preferably 0.2% by mass or less, more preferably 0.1% by mass or less, and even more preferably 0.01% by mass or less.
  • the electrical conductivity is less likely to decrease, and the strength of the negative electrode active material is less likely to decrease.
  • the total amount of unavoidable impurities with respect to the total amount of aluminum-containing metal is preferably 0% by mass, but examples of the lower limit include 0.00001% by mass or more and 0.0001% by mass or more.
  • the total amount of inevitable impurities with respect to the total amount of aluminum-containing metals is 0% by mass or more and 0.2% by mass or less, 0.00001% by mass or more and 0.1% by mass or less, and 0.0001% by mass or more and 0.01% by mass or less. be done.
  • Impurity elements contained in the inevitable impurities are, for example, one or more elements selected from the group consisting of Cu, Mn, Ni and V.
  • the total content of impurity elements with respect to the total mass of the aluminum-containing metal is preferably 50 mass ppm or less, more preferably 40 mass ppm or less, and even more preferably 30 mass ppm or less.
  • the total content of impurity elements listed above is equal to or less than the above upper limit, the electrical conductivity is less likely to decrease.
  • the total content of impurity elements with respect to the total mass of the aluminum-containing metal is preferably 0 ppm by mass, but examples of the lower limit include 0.001 ppm by mass or more and 0.01 ppm by mass or more.
  • the above upper limit and lower limit of the total content of impurity elements can be combined arbitrarily. Examples of combinations include a total impurity element content of 0 mass ppm to 50 mass ppm, 0.001 mass ppm to 40 mass ppm, and 0.001 mass ppm to 30 mass ppm.
  • the negative electrode active material can be produced by a production method comprising, in this order, a melting step, a vacuum treatment step, a step of adding a grain refiner for aluminum, a casting step, and a foil forming step.
  • melting process for example, aluminum is melted at a temperature of about 680° C. or higher and 800° C. or lower, and cleaning is performed by removing gases and non-metallic inclusions, which are generally known.
  • an aluminum-containing molten metal By adding a predetermined amount of another metal element during melting, an aluminum-containing molten metal can be obtained.
  • the other metal element is, for example, the element X described above, and it is preferable to add high-purity silicon as the Si source.
  • high-purity aluminum It is preferable to use high-purity aluminum as aluminum.
  • the purity of high-purity aluminum is preferably 99% by mass or higher, more preferably 99.9% by mass or higher, even more preferably 99.95% by mass or higher, and particularly preferably 99.99% by mass or higher.
  • the purity of high-purity aluminum can be confirmed by solid-state emission spectroscopy. Examples of refining methods for purifying aluminum to the above purity include a segregation method and a three-layer electrolysis method.
  • the segregation method is a purification method that utilizes the segregation phenomenon during solidification of molten aluminum, and a plurality of methods have been put into practical use.
  • the segregation method there is a method of pouring molten aluminum into a container, heating the upper molten aluminum while rotating the container, and solidifying refined aluminum from the bottom while stirring. Aluminum with a purity of 99.99% by mass or more can be obtained by the segregation method.
  • Three-Layer Electrolysis Method As one form of the three-layer electrolysis method, first, aluminum or the like (for example, a grade of about 1 according to JIS-H2102 with a purity of 99% by mass) is put into the Al—Cu alloy layer. Thereafter, the molten state is used as an anode, and an electrolytic bath containing, for example, aluminum fluoride and barium fluoride is placed thereon to deposit high-purity aluminum on the cathode. High-purity aluminum with a purity of 99.999% by mass or more can be obtained by the three-layer electrolysis method.
  • aluminum or the like for example, a grade of about 1 according to JIS-H2102 with a purity of 99% by mass
  • an electrolytic bath containing, for example, aluminum fluoride and barium fluoride is placed thereon to deposit high-purity aluminum on the cathode.
  • High-purity aluminum with a purity of 99.999% by mass or more can be obtained by the three-layer electrolysis method.
  • the refining method for highly purifying aluminum is not limited to the segregation method and the three-layer electrolysis method, and other known methods such as the zone melting refining method and the ultra-high vacuum melting refining method may be used.
  • the vacuum treatment is performed, for example, at a temperature of 700° C. to 800° C., 1 hour to 10 hours, and a degree of vacuum of 0.1 Pa to 100 Pa.
  • a grain refiner for aluminum is added to the molten metal after the vacuum treatment.
  • grain refiners for aluminum include aluminum titanium boron and titanium boron.
  • Commercially available grain refiners for aluminum include, for example, KBM Affilips B.V. V. AlTiB5/1 manufactured by Co., Ltd. can be mentioned.
  • the amount of the grain refiner for aluminum added is, for example, a Ti content of 10 mass ppm or more and 1000 mass ppm or less based on the total mass of the aluminum-containing metal, and a B content of B based on the total mass of the aluminum-containing metal. It is preferable to adjust the amount to satisfy 2 mass ppm or more and 200 mass ppm or less.
  • a negative electrode active material that satisfies the above (1) can be obtained by adding a grain refiner for aluminum.
  • the amount of the grain refiner for aluminum added is increased, the area-weighted average grain diameter of the equivalent circle diameter of grains becomes smaller.
  • the refined crystals can be easily elongated in the rolling direction by rolling, and a negative electrode active material that satisfies the above (2) can be obtained.
  • the mold is made of iron or graphite heated to 50°C or higher and 200°C or lower.
  • the aluminum-containing metal is cast by a method of pouring molten metal at a temperature of 680° C. or more and 800° C. or less into a mold.
  • An ingot can also be obtained by continuous casting, which is generally used.
  • the obtained aluminum-containing ingot becomes a rolled material by rolling.
  • it may be processed into a plate-like shape in this step.
  • hot rolling and cold rolling are performed to process the aluminum-containing ingot into a foil shape.
  • the temperature conditions for hot rolling include, for example, setting the temperature of the aluminum-containing ingot at 350° C. or higher and 450° C. or lower.
  • the working rate r is 2% or more and 20% or less.
  • an intermediate annealing treatment may be performed before cold rolling.
  • a hot-rolled aluminum-containing ingot may be heated to 350° C. or higher and 450° C. or lower, and immediately allowed to cool after the temperature rise.
  • the aluminum-containing ingot may be allowed to cool after being held for about 1 to 5 hours.
  • Cold rolling is carried out, for example, at a temperature lower than the recrystallization temperature of the aluminum-containing ingot, usually from room temperature to 80 ° C. or less, and in a single-pass die, with a reduction rate r of 1% or more and 10% or less. This process is repeated until the ingot containing ingot reaches the desired thickness.
  • the metal negative electrode of this embodiment is made of the negative electrode active material of this embodiment, and is capable of intercalating and deintercalating lithium ions.
  • One aspect of the metal negative electrode of the present embodiment is a collector-combined negative electrode that functions both as a negative electrode and as a negative electrode current collector. According to the collector-combined negative electrode, a separate collector member is not required.
  • the metal negative electrode of the present embodiment includes the negative electrode active material of the present embodiment and a negative electrode current collector.
  • the negative electrode current collector can be a strip-shaped member made of a metal material.
  • the metal material one selected from the group consisting of Al, Cu, Ni, Mg, and Mn may be used alone, an alloy containing at least two of these may be used, and stainless steel may be used. good.
  • the material of the current collector it is preferable to use at least one of Cu and Al as a forming material and process it into a thin film because it is difficult to form an alloy with lithium and is easy to process. Further, when a negative electrode current collector is used, a clad material in which the negative electrode and the negative electrode current collector are laminated so as to be integrated may be used.
  • the joint surfaces of the negative electrode and the negative electrode current collector are each degreased and polished in one direction using a brush or the like. Thereby, the surface roughness Ra of the joint surface of the negative electrode and the surface roughness Ra of the joint surface of the negative electrode current collector are adjusted to 0.7 ⁇ m or more.
  • a laminate is obtained by aligning the joint surfaces of the negative electrode and the negative electrode current collector.
  • the obtained laminate is preheated at 300-500° C. and hot-rolled under the condition that the rolling reduction in the first rolling is 45-70%. After that, cold rolling is additionally performed to obtain a rolled material having a negative electrode thickness of 5 to 550 ⁇ m, that is, a clad material.
  • a lead wire is connected to the metal negative electrode.
  • a negative electrode using the negative electrode active material of the present invention as a negative electrode active material of a battery and a secondary battery having this negative electrode will be described while describing the structure of the battery.
  • a lithium secondary battery using a lithium positive electrode active material for the positive electrode will be described below as an example.
  • An example of a lithium secondary battery suitable for using the negative electrode active material of the present embodiment includes a positive electrode and a negative electrode, a separator sandwiched between the positive electrode and the negative electrode, and an electrolytic solution placed between the positive electrode and the negative electrode. have.
  • An example of a lithium secondary battery has a positive electrode and a negative electrode, a separator sandwiched between the positive electrode and the negative electrode, and an electrolytic solution placed between the positive electrode and the negative electrode.
  • FIG. 3 is a schematic diagram showing an example of a lithium secondary battery.
  • the cylindrical lithium secondary battery 10 of this embodiment is manufactured as follows.
  • a pair of strip-shaped separators 1, a strip-shaped positive electrode 2 having a positive electrode lead 21 at one end, and a strip-shaped negative electrode 3 having a negative electrode lead 31 at one end are arranged as follows: 1 and the negative electrode 3 are stacked in this order and wound to form an electrode group 4 .
  • the can bottom is sealed, the electrode group 4 is impregnated with the electrolytic solution 6, and the electrolyte is arranged between the positive electrode 2 and the negative electrode 3. . Further, by sealing the upper portion of the battery can 5 with the top insulator 7 and the sealing member 8, the lithium secondary battery 10 can be manufactured.
  • the shape of the electrode group 4 is, for example, a columnar shape such that the cross-sectional shape of the electrode group 4 cut in the direction perpendicular to the winding axis is a circle, an ellipse, a rectangle, or a rectangle with rounded corners. can be mentioned.
  • a shape defined by IEC60086 which is a standard for batteries defined by the International Electrotechnical Commission (IEC), or JIS C 8500 can be adopted.
  • IEC60086 which is a standard for batteries defined by the International Electrotechnical Commission (IEC), or JIS C 8500
  • a shape such as a cylindrical shape or a rectangular shape can be mentioned.
  • the lithium secondary battery is not limited to the wound type configuration described above, and may have a layered configuration in which a layered structure of a positive electrode, a separator, a negative electrode, and a separator is repeatedly stacked.
  • laminated lithium secondary batteries include so-called coin-type batteries, button-type batteries, and paper-type (or sheet-type) batteries.
  • the positive electrode can be manufactured by preparing a positive electrode mixture containing a positive electrode active material, a conductive material, and a binder, and supporting the positive electrode mixture on a positive electrode current collector.
  • lithium-containing compound or other metal compound can be used for the positive electrode active material.
  • lithium-containing compounds include lithium-cobalt composite oxides having a layered structure, lithium-nickel composite oxides having a layered structure, lithium-manganese composite oxides having a spinel structure, and lithium iron phosphate having an olivine structure. .
  • metal compounds include, for example, oxides such as titanium oxide, vanadium oxide or manganese dioxide, or sulfides such as titanium sulfide or molybdenum sulfide.
  • a carbon material can be used as the conductive material of the positive electrode.
  • Examples of carbon materials include graphite powder, carbon black (eg, acetylene black), and fibrous carbon materials.
  • the ratio of the conductive material in the positive electrode mixture is preferably 5-20 parts by mass with respect to 100 parts by mass of the positive electrode active material.
  • thermoplastic resin can be used as the binder of the positive electrode.
  • thermoplastic resins include polyimide resins; fluorine resins such as polyvinylidene fluoride (hereinafter sometimes referred to as PVdF) and polytetrafluoroethylene; polyolefin resins such as polyethylene and polypropylene; can be mentioned.
  • a strip-shaped member made of a metal material such as Al, Ni, or stainless steel can be used as the positive electrode current collector of the positive electrode.
  • the positive electrode mixture As a method for supporting the positive electrode mixture on the positive electrode current collector, the positive electrode mixture is made into a paste using an organic solvent, the obtained positive electrode mixture paste is applied to at least one side of the positive electrode current collector and dried, A method of fixing by performing an electrode pressing process can be mentioned.
  • organic solvents examples include N-methyl-2-pyrrolidone (hereinafter sometimes referred to as NMP).
  • Examples of the method for applying the positive electrode mixture paste to the positive electrode current collector include a slit die coating method, a screen coating method, a curtain coating method, a knife coating method, a gravure coating method, and an electrostatic spray method.
  • a positive electrode can be manufactured by the method mentioned above.
  • a metal negative electrode made of the negative electrode active material of the present embodiment is used as the negative electrode of the lithium secondary battery.
  • the negative electrode current collector When the metal negative electrode of this embodiment also serves as a current collector, the negative electrode current collector is unnecessary.
  • a band-shaped member made of a metal material such as Cu, Ni, or stainless steel can be used.
  • separator of the lithium secondary battery for example, a material having the form of a porous film, nonwoven fabric, or woven fabric made of a material such as a polyolefin resin such as polyethylene and polypropylene, a fluororesin, or a nitrogen-containing aromatic polymer is used. can be used. Moreover, the separator may be formed using two or more of these materials, or the separator may be formed by laminating these materials. Also, the separator described in JP-A-2000-030686 or US20090111025A1 may be used.
  • Electrode An electrolytic solution that a lithium secondary battery has contains an electrolyte and an organic solvent.
  • Electrolytes contained in the electrolytic solution include LiClO 4 , LiPF 6 , LiAsF 6 , LiSbF 6 , LiBF 4 , LiCF 3 SO 3 , LiN(SO 2 CF 3 ) 2 , LiN(SO 2 C 2 F 5 ) 2 , LiN ( SO2CF3 )( COCF3 ) , Li ( C4F9SO3 ), LiC(SO2CF3)3 , Li2B10Cl10 , LiBOB ( where BOB is bis(oxalato)borate ), LiFSI (where FSI is bis(fluorosulfonyl)imide), lower aliphatic carboxylic acid lithium salts and lithium salts such as LiAlCl4 , mixtures of two or more thereof may be used.
  • the electrolyte is at least selected from the group consisting of LiPF6 , LiAsF6 , LiSbF6 , LiBF4 , LiCF3SO3 , LiN( SO2CF3 ) 2 and LiC ( SO2CF3 ) 3 containing fluorine. It is preferred to use one containing one.
  • organic solvent contained in the electrolytic solution examples include propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, 4-trifluoromethyl-1,3-dioxolan-2-one and 1,2-dioxolan-2-one.
  • Carbonates such as (methoxycarbonyloxy)ethane; 1,2-dimethoxyethane, 1,3-dimethoxypropane, pentafluoropropylmethyl ether, 2,2,3,3-tetrafluoropropyldifluoromethyl ether, tetrahydrofuran and 2- ethers such as methyltetrahydrofuran; esters such as methyl formate, methyl acetate, propyl propionate and ⁇ -butyrolactone; nitriles such as acetonitrile and butyronitrile; amides such as N,N-dimethylformamide and N,N-dimethylacetamide.
  • Carbamates such as 3-methyl-2-oxazolidone; Sulfur-containing compounds such as sulfolane, dimethyl sulfoxide and 1,3-propanesultone, or those obtained by further introducing a fluoro group into these organic solvents (hydrogen contained in organic solvents one or more atoms of which are substituted with fluorine atoms) can be used.
  • the electrolyte may contain additives such as tris (trimethylsilyl) phosphate and tris (trimethylsilyl) borate.
  • the organic solvent it is preferable to use a mixture of two or more of these.
  • a mixed solvent containing carbonates is preferable, and a mixed solvent of a cyclic carbonate and a non-cyclic carbonate and a mixed solvent of a cyclic carbonate and an ether are more preferable.
  • the electrolytic solution it is preferable to use an electrolytic solution containing a fluorine-containing lithium salt such as LiPF 6 and an organic solvent having a fluorine substituent, since the safety of the obtained lithium secondary battery is increased.
  • a fluorine-containing lithium salt such as LiPF 6
  • an organic solvent having a fluorine substituent since the safety of the obtained lithium secondary battery is increased.
  • the electrolyte and organic solvent contained in the electrolytic solution the electrolyte and organic solvent described in WO2019/098384A1 or US2020/0274158A1 may be used.
  • FIG. 4 is a schematic diagram showing an example of the all-solid lithium secondary battery of this embodiment.
  • the all-solid lithium secondary battery 1000 shown in FIG. 4 has a laminate 100 having a positive electrode 110, a negative electrode 120, and a solid electrolyte layer 130, and an exterior body 200 that accommodates the laminate 100.
  • the all-solid lithium secondary battery 1000 may have a bipolar structure in which a positive electrode active material and a negative electrode active material are arranged on both sides of a current collector.
  • bipolar structures include structures described in JP-A-2004-95400. The material forming each member will be described later.
  • the laminate 100 may have an external terminal 113 connected to the positive electrode current collector 112 and an external terminal 123 connected to the negative electrode current collector 122 .
  • all-solid lithium secondary battery 1000 may have a separator between positive electrode 110 and negative electrode 120 .
  • the all-solid lithium secondary battery 1000 further has an insulator (not shown) for insulating the laminate 100 and the exterior body 200 and a sealing body (not shown) for sealing the opening 200 a of the exterior body 200 .
  • a container molded from a highly corrosion-resistant metal material such as aluminum, stainless steel, or nickel-plated steel can be used.
  • a container in which a laminated film having at least one surface subjected to corrosion-resistant processing is processed into a bag shape can also be used.
  • Examples of the shape of the all-solid lithium secondary battery 1000 include coin-shaped, button-shaped, paper-shaped (or sheet-shaped), cylindrical, rectangular, and laminate-shaped (pouch-shaped).
  • the all-solid-state lithium secondary battery 1000 is illustrated as having one laminate 100 as an example, but the present embodiment is not limited to this.
  • the all-solid lithium secondary battery 1000 may have a configuration in which the laminate 100 is used as a unit cell and a plurality of unit cells (laminate 100 ) are sealed inside the exterior body 200 .
  • the positive electrode 110 has a positive electrode active material layer 111 and a positive electrode current collector 112 .
  • the positive electrode active material layer 111 contains a positive electrode active material and a solid electrolyte. Moreover, the positive electrode active material layer 111 may contain a conductive material and a binder.
  • solid electrolyte As the solid electrolyte contained in the positive electrode active material layer 111, a solid electrolyte having lithium ion conductivity and used in known all-solid lithium secondary batteries can be employed.
  • solid electrolytes include inorganic electrolytes and organic electrolytes.
  • inorganic electrolytes include oxide-based solid electrolytes, sulfide-based solid electrolytes, and hydride-based solid electrolytes.
  • organic electrolytes include polymer-based solid electrolytes.
  • each electrolyte include compounds described in WO2020/208872A1, US2016/0233510A1, US2012/0251871A1, and US2018/0159169A1, and examples thereof include the following compounds.
  • oxide-based solid electrolytes examples include perovskite-type oxides, NASICON-type oxides, LISICON-type oxides, and garnet-type oxides. Specific examples of each oxide include compounds described in WO2020/208872A1, US2016/0233510A1, and US2020/0259213A1, and examples thereof include the following compounds.
  • Perovskite oxides include Li—La—Ti-based oxides such as Li a La 1-a TiO 3 (0 ⁇ a ⁇ 1), Li b La 1-b TaO 3 (0 ⁇ b ⁇ 1) and the like. Examples thereof include Li—La—Ta-based oxides and Li—La—Nb-based oxides such as Li c La 1-c NbO 3 (0 ⁇ c ⁇ 1).
  • NASICON-type oxides examples include Li 1+d Al d Ti 2-d (PO 4 ) 3 (0 ⁇ d ⁇ 1).
  • the NASICON-type oxide is Li m M 1 n M 2 o P p O q (where M 1 is selected from the group consisting of B, Al, Ga, In, C, Si, Ge, Sn, Sb and Se).
  • M 1 is selected from the group consisting of B, Al, Ga, In, C, Si, Ge, Sn, Sb and Se).
  • M2 is one or more elements selected from the group consisting of Ti, Zr, Ge, In, Ga, Sn and Al m, n, o, p and q is an arbitrary positive number).
  • Li 4 M 3 O 4 —Li 3 M 4 O 4 (M 3 is one or more elements selected from the group consisting of Si, Ge, and Ti.
  • M 4 is P is one or more elements selected from the group consisting of , As and V).
  • Garnet-type oxides include Li—La—Zr-based oxides such as Li 7 La 3 Zr 2 O 12 (also referred to as LLZ).
  • the oxide-based solid electrolyte may be a crystalline material or an amorphous material.
  • sulfide-based solid electrolyte examples include Li 2 SP 2 S 5 based compounds, Li 2 S—SiS 2 based compounds, Li 2 S—GeS 2 based compounds, Li 2 S—B 2 S 3 based compounds, LiI- Si 2 SP 2 S 5 based compounds, LiI-Li 2 SP 2 O 5 based compounds, LiI-Li 3 PO 4 -P 2 S 5 based compounds and Li 10 GeP 2 S 12 based compounds, etc. can be done.
  • based compound that refers to a sulfide-based solid electrolyte refers to a solid electrolyte that mainly contains raw materials such as "Li 2 S" and "P 2 S 5 " described before "based compound".
  • Li 2 SP 2 S 5 based compounds include solid electrolytes that mainly contain Li 2 S and P 2 S 5 and further contain other raw materials.
  • the ratio of Li 2 S contained in the Li 2 SP 2 S 5 based compound is, for example, 50 to 90% by mass with respect to the entire Li 2 SP 2 S 5 based compound.
  • the ratio of P 2 S 5 contained in the Li 2 SP 2 S 5 based compound is, for example, 10 to 50% by mass with respect to the entire Li 2 SP 2 S 5 based compound.
  • the ratio of other raw materials contained in the Li 2 SP 2 S 5 compound is, for example, 0 to 30% by mass with respect to the entire Li 2 SP 2 S 5 compound.
  • the Li 2 SP 2 S 5 -based compound also includes solid electrolytes in which the mixing ratio of Li 2 S and P 2 S 5 is varied.
  • Li 2 SP 2 S 5 compounds include Li 2 SP 2 S 5 , Li 2 SP 2 S 5 -LiI, Li 2 SP 2 S 5 -LiCl, Li 2 SP 2 S5 - LiBr, Li2SP2S5 - LiI - LiBr, Li2SP2S5 - Li2O , Li2SP2S5 - Li2O - LiI and Li2S- P 2 S 5 -Z m S n (m and n are positive numbers, Z is Ge, Zn or Ga).
  • Li 2 S—SiS 2 compounds include Li 2 S—SiS 2 , Li 2 S—SiS 2 —LiI, Li 2 S—SiS 2 —LiBr, Li 2 S—SiS 2 —LiCl, and Li 2 S—SiS.
  • Li 2 S—GeS 2 based compounds examples include Li 2 S—GeS 2 and Li 2 S—GeS 2 —P 2 S 5 .
  • the sulfide-based solid electrolyte may be a crystalline material or an amorphous material.
  • hydride solid electrolyte materials include LiBH 4 , LiBH 4 -3KI, LiBH 4 -PI 2 , LiBH 4 -P 2 S 5 , LiBH 4 -LiNH 2 , 3LiBH 4 -LiI, LiNH 2 , Li 2 AlH 6 , Li( NH2 )2I, Li2NH, LiGd(BH4) 3Cl , Li2(BH4) ( NH2 ) , Li3 ( NH2 ) I and Li4 ( BH4) ( NH2 ) 3 etc. can be mentioned.
  • polymer solid electrolyte examples include organic polymer electrolytes such as polyethylene oxide-based polymer compounds and polymer compounds containing one or more selected from the group consisting of polyorganosiloxane chains and polyoxyalkylene chains. .
  • organic polymer electrolytes such as polyethylene oxide-based polymer compounds and polymer compounds containing one or more selected from the group consisting of polyorganosiloxane chains and polyoxyalkylene chains.
  • a so-called gel type in which a non-aqueous electrolyte is held in a polymer compound can also be used.
  • Two or more kinds of solid electrolytes can be used together as long as the effects of the invention are not impaired.
  • (Conductive material and binder) As the conductive material included in the positive electrode active material layer 111, the materials described in (Conductive material) can be used. Also, the ratio described in the above (Conductive material) can be similarly applied to the ratio of the conductive material in the positive electrode mixture. Further, as the binder contained in the positive electrode, the materials described in the above (Binder) can be used.
  • a mixture of the positive electrode active material, the solid electrolyte, the conductive material, and the binder is pasted using an organic solvent to form a positive electrode mixture, and the obtained positive electrode mixture is applied to at least one surface of the positive electrode current collector 112 and dried.
  • the positive electrode current collector 112 may carry the positive electrode active material layer 111 by pressing and fixing.
  • a mixture of the positive electrode active material, the solid electrolyte, and the conductive material is pasted using an organic solvent to form a positive electrode mixture, and the obtained positive electrode mixture is applied to at least one surface of the positive electrode current collector 112, dried, and baked.
  • the positive electrode current collector 112 may support the positive electrode active material layer 111 .
  • the same positive electrode active material as described in the above (positive electrode active material) can be used.
  • the organic solvent that can be used for the positive electrode mixture the same organic solvent that can be used when the positive electrode mixture is made into a paste as described in (Positive electrode current collector) can be used.
  • Examples of the method of applying the positive electrode mixture to the positive electrode current collector 112 include the methods described above in (Positive electrode current collector).
  • the positive electrode 110 can be manufactured by the method described above. Specific combinations of materials used for the positive electrode 110 include positive electrode active materials and combinations listed in Table 1.
  • the negative electrode 120 has a negative electrode active material layer 121 and a negative electrode current collector 122 .
  • a metal negative electrode made of the negative electrode active material of this embodiment is used for the negative electrode active material layer 121 .
  • the negative electrode current collector is unnecessary.
  • the negative electrode current collector 122 can be a strip-shaped member made of a metal material such as Cu, Ni, or stainless steel.
  • the solid electrolyte layer 130 has the solid electrolyte described above.
  • the solid electrolyte layer 130 As an example of a method for manufacturing the solid electrolyte layer 130, a solid electrolyte of an inorganic material is sputtered on the surface of the positive electrode active material layer 111 of the positive electrode 110 described above, or a paste mixture containing a solid electrolyte is applied and dried. method.
  • the solid electrolyte layer 130 may be formed by press-molding after drying and further pressing by cold isostatic pressing (CIP).
  • Laminate 100 is obtained by laminating negative electrode 120 on solid electrolyte layer 130 provided on positive electrode 110 as described above, using a known method, in such a manner that negative electrode active material layer 121 is in contact with the surface of solid electrolyte layer 130 . It can be manufactured by
  • composition analysis of the negative electrode active material was performed by the method described in [Composition analysis] above.
  • a negative electrode active material was manufactured by a method described later, and a negative electrode made of the negative electrode active material was manufactured.
  • lithium cobalt oxide product name: Cellseed, manufactured by Nippon Kagaku Kogyo Co., Ltd., average particle size (D50): 10 ⁇ m
  • 5 parts by mass of polyvinylidene fluoride manufactured by Kureha Co., Ltd.
  • a conductive material 5 parts by mass of acet
  • the obtained electrode mixture was applied onto an aluminum foil having a thickness of 15 ⁇ m as a current collector by a doctor blade method.
  • the coated electrode mixture was dried at 60° C. for 2 hours and then vacuum dried at 150° C. for 10 hours to volatilize N-methyl-2-pyrrolidone.
  • the coating amount of the positive electrode active material after drying was 21.5 mg/cm 2 .
  • the positive electrode mixture layer after rolling had a thickness of 60 to 65 ⁇ m and an electrode density of 3.0 to 3.5 g/cm 3 .
  • a polyethylene porous separator is placed between the negative electrode and the positive electrode, housed in a battery case (standard 2032), the above electrolytic solution is injected, and the battery case is sealed to obtain a diameter of 20 mm and a thickness of 20 mm.
  • a 3.2 mm coin-type (full cell) lithium secondary battery was produced.
  • materials that react with moisture such as electrolytes, lithium metal, and electrodes after charging, avoid contact with the inside of a glove box controlled at a moisture content of 1 mass ppm or less, or with equivalent moisture as much as possible. done in the environment.
  • Cycle/discharge evaluation charge/discharge efficiency at 20th cycle
  • charging at 1 mA (0.2C) and discharging at 1 mA (0.2C) were repeated under the same conditions as the initial charge/discharge.
  • Life evaluation was performed by 6-time and 20-time cycle tests, and the cycle maintenance rate was calculated by the following formula.
  • Cycle maintenance rate (%) discharge capacity at 20th cycle (mAh)/discharge capacity at 6th cycle (mAh) x 100
  • Example 1>> (Casting process) 4455 g of aluminum (purity: 99.99% by mass or more) and 45 g of Tokuyama silicon (purity: 99.999% by mass or more) were weighed. Next, silicon was added to the melted aluminum, and the mixture was heated and held at 780° C. to obtain an Al—Si alloy melt having a silicon content of 1.0% by mass. Next, the molten alloy was held at a temperature of 760° C. and a degree of vacuum of 50 Pa for 2 hours for cleaning. After cleaning, a commercially available Al-Ti-B alloy (Al:Ti:B 94:5:1, manufactured by KBM Affilips B.V. in the Netherlands, AlTiB5 /1) was added and immediately stirred for 1 minute to obtain a molten alloy.
  • the molten alloy was cast using a cast iron mold (22 mm x 150 mm x 200 mm) dried at 150°C to obtain an ingot.
  • the area-weighted average grain diameter of the equivalent circle diameter of the grains of the aluminum phase is 3.8 ⁇ m
  • the aspect ratio of the grains is 1.9
  • the standard deviation of the aspect ratio is 0.87. Met.
  • the obtained aluminum-containing metal foil 1 (thickness 50 ⁇ m) was cut into a disk shape of ⁇ 15 mm to manufacture a negative electrode.
  • the cycle maintenance rate calculated by the above method was 97%.
  • the non-aluminum phase was dispersed in the aluminum phase.
  • the non-aluminum phase contained 83 mass ppm of Ti and 17 mass ppm of B.
  • the area-weighted average grain diameter of the equivalent circle diameter of the grains of the aluminum phase is 2.6 ⁇ m
  • the aspect ratio of the grains is 1.9
  • the standard deviation of the aspect ratio is 0.83.
  • the non-aluminum phase was dispersed in the aluminum phase.
  • the non-aluminum phase contained 250 mass ppm of Ti and 50 mass ppm of B.
  • the area-weighted average grain diameter of the equivalent circle diameter of the grains of the aluminum phase is 2.0 ⁇ m
  • the aspect ratio of the grains is 1.7
  • the standard deviation of the aspect ratio is 0.46. Met.
  • the non-aluminum phase was dispersed in the aluminum phase.
  • the non-aluminum phase contained 830 mass ppm of Ti and 170 mass ppm of B.
  • the area-weighted average grain diameter of the equivalent circle diameter of the grains of the aluminum phase is 1.7 ⁇ m
  • the aspect ratio of the grains is 1.8
  • the standard deviation of the aspect ratio is 0.62. Met.
  • Aluminum-containing metal 5 was obtained in the same manner as in Example 1, except that no Al--Ti--B alloy was added.
  • the aluminum-containing metal foil 5 contained 1.0% by mass of Si.
  • the area-weighted average grain diameter of the equivalent circle diameter of the aluminum phase crystal grains is 4.8 ⁇ m
  • the aspect ratio of the crystal grains is 1.6
  • the standard deviation of the aspect ratio is 0.93. Met.
  • ⁇ Comparative Example 1> (Casting process) 4500 g of aluminum (purity: 99.99% by mass or more) was weighed. Next, molten aluminum was obtained by heating and holding at 780° C. to melt aluminum. Next, the molten Al was cleaned by holding it at a temperature of 760° C. and a vacuum degree of 50 Pa for 2 hours.
  • a cast iron mold (22 mm ⁇ 150 mm ⁇ 200 mm) dried at 150°C was used to cast molten Al to obtain an ingot.
  • the area-weighted average grain diameter of the equivalent circle diameter of the crystal grains of the aluminum phase was 12.1 ⁇ m. Since the average grain size of aluminum foil 1 was too large, the aspect ratio could not be measured.
  • Table 4 below shows the composition, area-weighted average particle size, aspect ratio, standard deviation of the aspect ratio, non-aluminum phase content, and Ti content for the negative electrode active materials of Examples 1 to 4, Reference Example 1, and Comparative Example 1. rate, B content, total amount of unavoidable impurities, impurity elements and their total content, and cycle characteristics.
  • a clad material obtained by laminating the negative electrode active material of Example 1-4 and a negative electrode current collector can be used as a negative electrode.
  • An example in which the clad material is used as the negative electrode will be described below.
  • Example 1 Using the aluminum-containing metal foil 1 prepared by the same procedure as in Example 1 as a negative electrode active material layer, and further using a rolled material of A5052 alloy as a current collector layer, the following surface treatment and rolling of the laminate were performed. An aluminum-containing metal laminate 1 including a negative electrode active material layer and a current collector layer is manufactured.
  • the bonding surfaces of the aluminum-containing metal foil 1, which is the negative electrode active material layer material, and the aluminum-magnesium alloy, which is the current collector layer material, are degreased and polished in one direction using a brush. Thereby, the surface roughness Ra of the joint surface of the aluminum-containing metal foil 1 is adjusted to 1.0 ⁇ m, and the surface roughness Ra of the joint surface of the aluminum-magnesium alloy is adjusted to 1.0 ⁇ m.
  • a laminate 1 was obtained by combining the joint surfaces of the aluminum-containing metal foil 1 and the aluminum-magnesium alloy.
  • the obtained laminate 1 is preheated at 350° C. and hot rolled under the condition that the rolling reduction in the first rolling is 50%. After that, additional cold rolling is performed to obtain a rolled material having a negative electrode active material layer with a thickness of 25 ⁇ m.
  • Example 2 Using the aluminum-containing metal foil 1 prepared by the same procedure as in Example 1 as a negative electrode active material layer, and further using a rolled material of A5052 alloy as a current collector layer, the following surface treatment and rolling of the laminate were performed. An aluminum-containing metal laminate 2 comprising a negative electrode active material layer and a current collector layer is manufactured.
  • the bonding surfaces of the aluminum-containing metal foil 1, which is the negative electrode active material layer material, and the aluminum-manganese alloy, which is the current collector layer material, are degreased and polished in one direction using a brush. Thereby, the surface roughness Ra of the joint surface of the aluminum-containing metal foil 1 is adjusted to 1.0 ⁇ m, and the surface roughness Ra of the joint surface of the aluminum-manganese alloy is adjusted to 1.0 ⁇ m.
  • a laminate 1 was obtained by joining the joint surfaces of the aluminum-containing metal foil 1 and the aluminum-manganese alloy.
  • the obtained laminate 1 is preheated at 350° C. and hot rolled under the condition that the rolling reduction in the first rolling is 50%. After that, additional cold rolling is performed to obtain a rolled material having a negative electrode active material layer with a thickness of 25 ⁇ m.
  • the aluminum-containing metal laminates of Production Examples 1 and 2 have the aluminum-containing metal foil 1 of Example 1 as a so-called negative electrode active material layer, and the composition, area-weighted average particle size, aspect ratio, and standard deviation of the aspect ratio , the content of the non-aluminum phase, the Ti content, the B content, the total amount of unavoidable impurities, the impurity elements and their total content are the same as in Example 1. Therefore, it can be fully inferred that the cycle characteristics of the lithium secondary batteries using the aluminum-containing metal laminates of Production Examples 1 and 2 are equivalent to or better than those of Examples 1-4.
  • the cycle maintenance rate calculated by the method described in ⁇ Evaluation of cycle characteristics of lithium secondary battery> is 97% or more and 102% or less.

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