WO2024157620A1 - 二次電池用正極活物質、二次電池用正極および二次電池 - Google Patents

二次電池用正極活物質、二次電池用正極および二次電池 Download PDF

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WO2024157620A1
WO2024157620A1 PCT/JP2023/043830 JP2023043830W WO2024157620A1 WO 2024157620 A1 WO2024157620 A1 WO 2024157620A1 JP 2023043830 W JP2023043830 W JP 2023043830W WO 2024157620 A1 WO2024157620 A1 WO 2024157620A1
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positive electrode
secondary battery
active material
electrode active
lithium
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English (en)
French (fr)
Japanese (ja)
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啓 長谷川
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Murata Manufacturing Co Ltd
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Murata Manufacturing Co Ltd
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Priority to US19/246,371 priority patent/US20250316690A1/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G53/00—Compounds of nickel
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G55/00—Compounds of ruthenium, rhodium, palladium, osmium, iridium, or platinum
    • 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • 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
    • H01M2004/028—Positive 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

  • This technology relates to positive electrode active materials for secondary batteries, positive electrodes for secondary batteries, and secondary batteries.
  • secondary batteries are being developed as small, lightweight power sources that can provide high energy density.
  • These secondary batteries have a positive electrode (a positive electrode active material for secondary batteries and a positive electrode for secondary batteries) and a negative electrode, as well as an electrolyte, and various studies are being conducted on the configuration of these secondary batteries.
  • the composite positive electrode active material includes secondary particles and a coating film, the secondary particles include a lithium transition metal oxide having a layered crystal structure, and the coating film includes a lithium cobalt composite oxide having a spinel crystal structure (see, for example, Patent Document 1).
  • the positive electrode active material layer includes a positive electrode active material and a coating layer, and the coating layer has a specific resistance within a predetermined range (see, for example, Patent Document 2).
  • the positive electrode active material sintered body includes a powder body and a coating layer, the powder body includes a lithium composite oxide, and the coating layer includes an amorphous lithium transition metal oxide (see, for example, Patent Document 3).
  • the electrode active material includes a lithium-nickel composite oxide and a lithium-transition metal M composite oxide, and the surface of the lithium-nickel composite oxide is coated with a lithium-transition metal M composite oxide (see, for example, Patent Document 4).
  • the positive electrode active material for a secondary battery includes a positive electrode active material.
  • This positive electrode active material includes a core and a coating portion that coats the surface of the core.
  • the core includes a first lithium composite oxide having a layered rock-salt crystal structure.
  • the coating portion includes a second lithium composite oxide having an orthorhombic crystal structure represented by the space group Immm and containing nickel as a constituent element.
  • the positive electrode for a secondary battery according to one embodiment of the present technology includes a positive electrode active material, and the positive electrode active material has a configuration similar to that of the positive electrode active material for a secondary battery according to one embodiment of the present technology described above.
  • the secondary battery of one embodiment of the present technology includes a positive electrode, a negative electrode, and an electrolyte, and the positive electrode has a configuration similar to that of the positive electrode for the secondary battery of one embodiment of the present technology described above.
  • the positive electrode active material for a secondary battery, the positive electrode for a secondary battery, or the secondary battery, the positive electrode active material for a secondary battery includes a core and a coating portion, the core portion includes a first lithium composite oxide having a layered rock-salt type crystal structure, and the coating portion includes a second lithium composite oxide having an orthorhombic crystal structure represented by the space group Immm and containing nickel as a constituent element, so that excellent battery characteristics can be obtained.
  • FIG. 1 is a cross-sectional view illustrating a configuration of a positive electrode active material for a secondary battery according to an embodiment of the present technology.
  • FIG. 2 is a perspective view illustrating a configuration of a secondary battery according to an embodiment of the present technology.
  • FIG. 3 is an enlarged cross-sectional view showing the configuration of the battery element shown in FIG.
  • FIG. 4 is a block diagram showing a configuration of an application example of a secondary battery.
  • FIG. 5 is a cross-sectional view showing the structure of a test secondary battery.
  • Positive electrode active material for secondary batteries 1-1. Composition 1-2. Manufacturing method 1-3. Actions and effects 2. Secondary batteries (positive electrodes for secondary batteries) 2-1. Configuration 2-2. Operation 2-3. Manufacturing method 2-4. Actions and effects 3. Modifications 4. Uses of secondary batteries
  • Positive electrode active material for secondary batteries First, a positive electrode active material for a secondary battery according to an embodiment of the present technology (hereinafter, simply referred to as a "positive electrode active material”) will be described.
  • the positive electrode active material described here is used in a secondary battery, which is an electrochemical device.
  • the positive electrode active material may also be used in electrochemical devices other than secondary batteries. Specific examples of other electrochemical devices include primary batteries and capacitors.
  • Fig. 1 shows a cross-sectional structure of a positive electrode active material 100, which is an example of a positive electrode active material.
  • This positive electrode active material 100 is a plurality of particulate substances that absorb and release lithium, and includes a central portion 110 and a coating portion 120, as shown in Fig. 1. However, Fig. 1 shows only one positive electrode active material 100.
  • the central portion 110 is a portion which substantially absorbs and releases lithium, and contains one or more types of the first lithium composite oxides.
  • This first lithium composite oxide is an oxide containing lithium and one or more transition metal elements as constituent elements, and has a layered rock-salt crystal structure.
  • the type of transition metal element is not particularly limited, but specific examples include nickel, cobalt, and manganese.
  • the first lithium composite oxide may further contain one or more metal elements other than the transition metal elements (hereinafter referred to as the "first additional metal element") as constituent elements.
  • the type of the first additional metal element is not particularly limited, but specific examples include aluminum and magnesium.
  • the first lithium composite oxide examples include LiNiO2 , LiCoO2 , and Li1.02Ni0.90Co0.05Al0.05O2 . , LiCo0.98Al0.01Mg0.01O2 , LiNi0.5Co0.2Mn0.3O2 and LiMn2O4 .
  • the reason why the central portion 110 contains the first lithium composite oxide is that a sufficient amount of lithium is absorbed and released in the central portion 110, so that a high battery capacity can be obtained in a secondary battery using the positive electrode active material 100.
  • the crystal structure of the first lithium composite oxide can be identified by analyzing the first lithium composite oxide using an analysis method such as powder X-ray diffraction.
  • copper is used as the X-ray target
  • the temperature of the analysis environment is room temperature (23°C)
  • the measurement range (2 ⁇ ) is 10° to 80°
  • the step operation is 0.01°/sec.
  • a material database is referred to in order to analyze the measurement chart, and a crystal structure is searched based on the interplanar spacing d calculated from the measurement result (2 ⁇ value), thereby identifying a crystal structure that matches the conditions such as the interplanar spacing of the peaks, the peak intensity ratio, the crystal system, and the lattice constant (database: Li 2 NiO 2 ICSD No. 25000).
  • the composition of the first lithium complex oxide can be determined by analyzing the first lithium complex oxide using an analytical method such as inductively coupled plasma (ICP) optical emission spectroscopy.
  • ICP inductively coupled plasma
  • the lithium, transition metal element, and first additional metal element are quantified, and the composition of the first lithium complex oxide is determined.
  • the first lithium complex oxide is dissolved in solution using a microwave decomposition method, and then the first lithium complex oxide is analyzed.
  • the covering portion 120 is a portion that covers the central portion 110, and contains any one or more types of the second lithium composite oxides.
  • the covering portion 120 may cover the entire surface of the central portion 110, or may cover only a portion of the surface of the central portion 110. In the latter case, a plurality of covering portions 120 spaced apart from one another may cover the surface of the central portion 110.
  • the second lithium composite oxide is an oxide containing lithium and nickel as constituent elements. Unlike the first lithium composite oxide described above, this second lithium composite oxide has an orthorhombic crystal structure represented by the space group Immm.
  • the second lithium composite oxide may further contain one or more metal elements other than nickel (hereinafter referred to as "second additional metal elements") as constituent elements.
  • This second additional metal element may be a transition metal element or a metal element other than a transition metal element.
  • the type of the second additional metal element is not particularly limited, but specific examples include titanium, platinum, copper, and tungsten.
  • the second lithium composite oxide contains one or more of the compounds represented by formula (1).
  • the second lithium composite oxide is an oxide containing lithium and nickel as constituent elements. As is clear from the range of x, the second lithium composite oxide may or may not contain the second metal element M as a constituent element.
  • the second lithium composite oxide examples include Li2NiO2 , Li2Ni0.99Ti0.01O2 , Li2Ni0.75Ti0.25O2 , Li2Ni0.75Pt0.25O2 , Li2Ni0.75Cu0.25O2 , and Li2Ni0.75W0.25O2 .
  • the reason why the coating portion 120 contains the second lithium composite oxide is that the highly reactive surface of the core portion 110 is electrochemically protected by the coating portion 120. This suppresses the decomposition reaction of the electrolyte on the surface of the core portion 110 in a secondary battery using the positive electrode active material 100. Therefore, even if the secondary battery is repeatedly charged and discharged, the increase in electrical resistance is suppressed and the decrease in discharge capacity is suppressed.
  • the second additional metal element M contains one or both of Cu and W as constituent elements. This is because the increase in electrical resistance is further suppressed when the secondary battery is repeatedly charged and discharged.
  • the second additional metal element M contains one or more of Ti, Pt, and Cu as constituent elements. This is because the decrease in discharge capacity is further suppressed when the secondary battery is repeatedly charged and discharged.
  • the average coating amount of the coating portion 120 is not particularly limited, but is preferably 0.01 mmol/m 2 to 0.05 mmol/m 2. This is because the state of coating the surface of the central portion 110 with the coating portion 120 is optimized, and the surface of the central portion 110 is sufficiently electrochemically protected by the coating portion 120. This sufficiently suppresses the decomposition reaction of the electrolyte, sufficiently suppressing an increase in electrical resistance and a decrease in discharge capacity.
  • the method of forming the covering portion 120 i.e., the method of covering the surface of the core portion 110 with the material from which the covering portion 120 is formed (hereinafter referred to as the "covering material"), is not particularly limited and can be selected arbitrarily.
  • the coating portion 120 is formed using a dry coating method.
  • this dry coating method the coating material is broken down by using shear force and adheres to the surface of the central portion 110. This fixes the coating material to the surface of the central portion 110, forming the coating portion 120. Note that when the coating material melts in response to thermal energy and is plastically deformed in response to mechanical energy, the coating material becomes a thin film that covers the surface of the central portion 110.
  • the crystal structure of the second lithium complex oxide can be identified by analyzing the second lithium complex oxide using an analysis method such as X-ray absorption spectroscopy (XAS).
  • XAS X-ray absorption spectroscopy
  • the crystal structure of the second lithium complex oxide is identified by analyzing the crystal structure based on the X-ray absorption near edge structure (XANES) using the first principles calculation program (FEFF) for X-ray absorption spectroscopy.
  • XANES X-ray absorption near edge structure
  • FEFF first principles calculation program
  • the procedure for determining the composition of the second lithium composite oxide is similar to the procedure for determining the composition of the first lithium composite oxide. However, in the procedure for determining the composition of the second lithium composite oxide, the second additional metal element is quantified instead of the first additional metal element.
  • the procedure for calculating the average coating amount of the coating portion 120 is as described below. Below, a case where the second lithium composite oxide contains the second additional metal element as a constituent element is described.
  • the positive electrode active material 100 is produced by the procedure of one example of which will be described below.
  • This raw material is a compound containing nickel as a constituent element, and may further contain a second additional metal element as a constituent element.
  • the type of raw material is not particularly limited, but specific examples include carbonates and hydroxides.
  • This precursor is an oxide containing nickel as a constituent element, and as described above, may further contain a second additional metal element as a constituent element.
  • the firing conditions such as the firing temperature and firing time, can be set as desired.
  • the precursor and the lithium compound are mixed together to obtain a mixture, and the mixture is then fired to obtain a fired product.
  • This lithium compound is a compound that contains lithium as a constituent element.
  • the firing conditions such as the firing temperature and firing time, can be set as desired.
  • the fired material is pulverized to obtain a pulverized product, and then a sieve is used to remove coarse particles from the pulverized product.
  • a sieve is used to remove coarse particles from the pulverized product.
  • a mortar or other pulverizing tool is used.
  • the mesh size ( ⁇ m) of the sieve is not particularly limited and can be set as desired.
  • This coating material contains a second lithium composite oxide having an orthorhombic crystal structure represented by the space group Immm.
  • the sintering conditions for sintering the mixture of the precursor and the lithium compound are adjusted to adjust the crystal structure of the coating material (second lithium composite oxide) so that it has an orthorhombic crystal structure represented by the space group Immm.
  • the cores 110 contain a first lithium composite oxide having a layered rock-salt type crystal structure.
  • the multiple cores 110 and the coating material are granulated.
  • a granulation device such as a centrifugal fluid granulation device is used.
  • the granulation conditions such as the granulation temperature and granulation time, can be set as desired.
  • the coating material is fixed to the surface of the central portion 110, forming the coating portion 120.
  • a plurality of positive electrode active materials 100 including the central portion 110 and the coating portion 120 are completed.
  • the average amount of coating on the coating portion 120 can be adjusted by adjusting the amount of coating material added when granulating using multiple cores 110 and the coating material.
  • the positive electrode active material 100 includes a core 110 and a coating portion 120.
  • the core 110 includes a first lithium composite oxide having a layered rock-salt crystal structure.
  • the coating portion 120 includes a second lithium composite oxide having an orthorhombic crystal structure represented by the space group Immm and containing nickel as a constituent element.
  • the central portion 110 contains the first lithium composite oxide, as described above, a sufficient amount of lithium is absorbed and released in the central portion 110. This allows a high battery capacity to be obtained in a secondary battery using the positive electrode active material 100.
  • the coating portion 120 contains the second lithium composite oxide, as described above, the highly reactive surface of the core portion 110 is electrochemically protected by the coating portion 120.
  • the decomposition reaction of the electrolyte on the surface of the core portion 110 is suppressed, so that even if the secondary battery is repeatedly charged and discharged, an increase in electrical resistance is suppressed and a decrease in discharge capacity is suppressed.
  • a secondary battery using the positive electrode active material 100 can obtain a high battery capacity, and the increase in electrical resistance and the decrease in discharge capacity are suppressed even when the battery is repeatedly charged and discharged. Therefore, a secondary battery having excellent battery characteristics can be realized by using the positive electrode active material 100.
  • the second lithium composite oxide contains the compound shown in formula (1), the surface of the core 110 is sufficiently electrochemically protected by the coating 120, and the decomposition reaction of the electrolyte is sufficiently suppressed. Therefore, an increase in electrical resistance is sufficiently suppressed, and a decrease in discharge capacity is sufficiently suppressed, resulting in a higher effect.
  • the second additional metal element M contains one or both of Cu and W as constituent elements, the increase in electrical resistance is further suppressed, and an even greater effect can be obtained.
  • the second additional metal element M contains one or more of Ti, Pt, and Cu as constituent elements, the decrease in discharge capacity is further suppressed, and an even greater effect can be obtained.
  • the surface of the center portion 110 is sufficiently electrochemically protected by the covering portion 120, and the decomposition reaction of the electrolyte is sufficiently suppressed. Therefore, an increase in electrical resistance is sufficiently suppressed, and a decrease in discharge capacity is sufficiently suppressed, resulting in a higher effect.
  • the positive electrode for a secondary battery is one component of the secondary battery described herein, and therefore the positive electrode will also be described below.
  • This secondary battery is one in which battery capacity is obtained by absorbing and releasing an electrode reactant, and is equipped with a positive electrode, a negative electrode, and an electrolyte. More specifically, a secondary battery in which battery capacity is obtained by absorbing and releasing lithium, an electrode reactant, is a so-called lithium-ion secondary battery. In this lithium-ion secondary battery, lithium is absorbed and released in an ionic state.
  • the charge capacity of the negative electrode is preferably greater than the discharge capacity of the positive electrode.
  • the electrochemical capacity per unit area of the negative electrode is preferably greater than the electrochemical capacity per unit area of the positive electrode. This is to prevent lithium from being deposited on the surface of the negative electrode during charging.
  • Fig. 2 shows a perspective view of the secondary battery
  • Fig. 3 shows an enlarged cross-sectional view of the battery element 20 shown in Fig. 2.
  • Fig. 2 shows a state in which the exterior film 10 and the battery element 20 are separated from each other, and shows a cross section of the battery element 20 along the XZ plane by a dashed line.
  • this secondary battery includes an exterior film 10, a battery element 20, a positive electrode lead 31, a negative electrode lead 32, and sealing films 41 and 42.
  • the secondary battery described here is a laminate film type secondary battery that uses a flexible or pliable exterior film 10.
  • the exterior film 10 is an exterior member that houses the battery element 20, and has a bag-like structure that is sealed when the battery element 20 is housed therein. As a result, the exterior film 10 houses an electrolyte together with a positive electrode 21 and a negative electrode 22, which will be described later.
  • the exterior film 10 is a single film-like member that is folded in the folding direction F.
  • This exterior film 10 is provided with a recessed portion 10U (a so-called deep drawn portion) for accommodating the battery element 20.
  • the exterior film 10 is a three-layer laminate film in which a fusion layer, a metal layer, and a surface protection layer are laminated in this order from the inside, and when the exterior film 10 is folded, the outer peripheral edges of the opposing fusion layers are fused to each other.
  • the fusion layer contains a polymer compound such as polypropylene.
  • the metal layer contains a metallic material such as aluminum.
  • the surface protection layer contains a polymer compound such as nylon.
  • the configuration (number of layers) of the exterior film 10, which is a laminate film is not particularly limited, and may be one or two layers, or four or more layers.
  • the battery element 20 is a power generating element including a positive electrode 21, a negative electrode 22, a separator 23, and an electrolyte (not shown), and is housed inside the exterior film 10.
  • This battery element 20 is a so-called wound electrode body. That is, the positive electrode 21 and the negative electrode 22 are wound around the winding axis P while facing each other via the separator 23.
  • This winding axis P is a virtual axis that extends in the Y-axis direction.
  • the three-dimensional shape of the battery element 20 is not particularly limited.
  • the battery element 20 is flat, and therefore the shape of the cross section (cross section along the XZ plane) of the battery element 20 intersecting the winding axis P is a flat shape defined by the long axis J1 and the short axis J2.
  • the long axis J1 is an imaginary axis that extends in the X-axis direction and has a length greater than the length of the short axis J2
  • the short axis J2 is an imaginary axis that extends in the Z-axis direction intersecting the X-axis direction and has a length smaller than the length of the long axis J1.
  • the three-dimensional shape of the battery element 20 is a flat cylindrical shape, and therefore the shape of the cross section of the battery element 20 is a flattened approximate ellipse.
  • the positive electrode 21 includes a positive electrode current collector 21A and a positive electrode active material layer 21B.
  • the positive electrode collector 21A has a pair of surfaces on which the positive electrode active material layer 21B is provided.
  • This positive electrode collector 21A contains a conductive material such as a metal material, and a specific example of the conductive material is aluminum.
  • the positive electrode active material layer 21B contains one or more types of positive electrode active materials that absorb and release lithium. However, the positive electrode active material layer 21B may further contain one or more types of other materials such as a positive electrode binder and a positive electrode conductor.
  • the method of forming the positive electrode active material layer 21B is not particularly limited, but specifically includes a coating method.
  • the positive electrode active material layer 21B is provided on both sides of the positive electrode collector 21A.
  • the positive electrode active material layer 21B may be provided on only one side of the positive electrode collector 21A on the side where the positive electrode 21 faces the negative electrode 22.
  • the positive electrode active material has a configuration similar to that of the positive electrode active material 100. Details regarding the configuration of the positive electrode active material 100 are as described above.
  • the positive electrode binder contains one or more of the following materials: synthetic rubber and polymeric compounds.
  • synthetic rubber include styrene-butadiene rubber, fluororubber, and ethylene-propylene-diene.
  • polymeric compounds include polyvinylidene fluoride, polyimide, and carboxymethyl cellulose.
  • the positive electrode conductive agent contains one or more conductive materials such as carbon materials, metal materials, and conductive polymer compounds.
  • conductive materials such as carbon materials, metal materials, and conductive polymer compounds.
  • Specific examples of carbon materials include graphite, carbon black, acetylene black, and ketjen black.
  • the negative electrode 22 includes a negative electrode current collector 22A and a negative electrode active material layer 22B.
  • the negative electrode current collector 22A has a pair of surfaces on which the negative electrode active material layer 22B is provided.
  • This negative electrode current collector 22A contains a conductive material such as a metal material, and a specific example of the conductive material is copper.
  • the negative electrode active material layer 22B contains one or more types of negative electrode active materials that absorb and release lithium. However, the negative electrode active material layer 22B may further contain one or more types of other materials such as a negative electrode binder and a negative electrode conductor.
  • the method of forming the negative electrode active material layer 22B is not particularly limited, but specifically includes one or more types of a coating method, a gas phase method, a liquid phase method, a thermal spraying method, and a baking method (sintering method).
  • the negative electrode active material layer 22B is provided on both sides of the negative electrode collector 22A.
  • the negative electrode active material layer 22B may be provided on only one side of the negative electrode collector 22A on the side where the negative electrode 22 faces the positive electrode 21.
  • the type of negative electrode active material is not particularly limited, but specific examples include carbon materials and metal-based materials, because they provide high energy density.
  • carbon materials include graphitizable carbon, non-graphitizable carbon, and graphite (natural graphite and artificial graphite).
  • the metal-based material is a material that contains one or more of metal elements and metalloid elements that can form an alloy with lithium as a constituent element, and specific examples of the metal elements and metalloid elements include silicon and tin.
  • the metal-based material may be a simple substance, an alloy, a compound, a mixture of two or more of them, or a material that contains two or more phases of them.
  • Specific examples of the metal-based material include TiSi2 and SiOx (0 ⁇ x ⁇ 2 or 0.2 ⁇ x ⁇ 1.4).
  • the separator 23 is an insulating porous film interposed between the positive electrode 21 and the negative electrode 22, and allows lithium ions to pass through while preventing contact (short circuit) between the positive electrode 21 and the negative electrode 22.
  • the separator 23 contains a polymer compound such as polyethylene.
  • the electrolyte is a liquid electrolyte that is impregnated into the positive electrode 21, the negative electrode 22, and the separator 23, and contains a solvent and an electrolyte salt.
  • the solvent contains one or more types of non-aqueous solvents (organic solvents), and the electrolyte containing the non-aqueous solvent is a so-called non-aqueous electrolyte.
  • the non-aqueous solvent is an ester or ether, and more specifically, a carbonate ester compound, a carboxylate ester compound, a lactone compound, etc. This is because the dissociation of the electrolyte salt is improved, and the mobility of the ions is also improved.
  • Carbonate compounds include cyclic carbonates and chain carbonates. Specific examples of cyclic carbonates include ethylene carbonate and propylene carbonate, while specific examples of chain carbonates include dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.
  • Carboxylic acid ester compounds include chain carboxylates, and specific examples of chain carboxylates include ethyl acetate, ethyl propionate, propyl propionate, and ethyl trimethylacetate.
  • Lactone compounds include lactones, and specific examples of lactones include ⁇ -butyrolactone and ⁇ -valerolactone.
  • Ethers may include 1,2-dimethoxyethane, tetrahydrofuran, 1,3-dioxolane, and 1,4-dioxane.
  • the electrolyte salt contains one or more of light metal salts such as lithium salts.
  • lithium salts include lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium trifluoromethanesulfonate (LiCF 3 SO 3 ), lithium bis(fluorosulfonyl)imide (LiN(FSO 2 ) 2 ), lithium bis(trifluoromethanesulfonyl)imide (LiN(CF 3 SO 2 ) 2 ), lithium tris(trifluoromethanesulfonyl)methide (LiC(CF 3 SO 2 ) 3 ), lithium bis(oxalato)borate (LiB(C 2 O 4 ) 2 ), lithium monofluorophosphate (Li 2 PFO 3 ), and lithium difluorophosphate (LiPF 2 O 2 ). This is because a high battery capacity can be obtained.
  • the amount of electrolyte salt contained is not particularly limited, but is typically 0.3 mol/kg to 3.0 mol/kg relative to the solvent. This is because high ionic conductivity is obtained.
  • the electrolyte may further contain one or more of the additives. This is because the electrochemical stability of the electrolyte is improved.
  • the type of additive include unsaturated cyclic carbonates, fluorinated cyclic carbonates, sulfonates, phosphates, acid anhydrides, nitrile compounds, and isocyanate compounds.
  • unsaturated cyclic carbonates include vinylene carbonate, vinylethylene carbonate, and methyleneethylene carbonate.
  • fluorinated cyclic carbonates include monofluoroethylene carbonate and difluoroethylene carbonate.
  • sulfonic acid esters include propane sultone and propene sultone.
  • phosphate esters include trimethyl phosphate and triethyl phosphate.
  • acid anhydrides include succinic anhydride, 1,2-ethanedisulfonic anhydride, and 2-sulfobenzoic anhydride.
  • nitrile compounds include succinonitrile.
  • isocyanate compounds include hexamethylene diisocyanate.
  • the positive electrode lead 31 is a positive electrode terminal connected to the positive electrode current collector 21A of the positive electrode 21, and is led out to the outside of the exterior film 10.
  • the positive electrode lead 31 contains a conductive material such as a metal material, and a specific example of the conductive material is aluminum.
  • the shape of the positive electrode lead 31 is not particularly limited, but is specifically either a thin plate shape or a mesh shape.
  • the negative electrode lead 32 is a negative electrode terminal connected to the negative electrode current collector 22A of the negative electrode 22, and is led out to the outside of the exterior film 10.
  • This negative electrode lead 32 contains a conductive material such as a metal material, and a specific example of the conductive material is copper.
  • the details regarding the lead-out direction and shape of the negative electrode lead 32 are the same as the details regarding the lead-out direction and shape of the positive electrode lead 31.
  • the sealing film 41 is inserted between the exterior film 10 and the positive electrode lead 31, and the sealing film 42 is inserted between the exterior film 10 and the negative electrode lead 32.
  • the sealing films 41 and 42 may be omitted.
  • This sealing film 41 is a sealing member that prevents outside air and the like from entering the inside of the exterior film 10.
  • the sealing film 41 contains a polymer compound such as polyolefin that has adhesion to the positive electrode lead 31, and a specific example of the polyolefin is polypropylene.
  • the configuration of the sealing film 42 is the same as that of the sealing film 41, except that the sealing film 42 is a sealing member that has adhesion to the negative electrode lead 32.
  • the sealing film 42 contains a polymer compound such as polyolefin that has adhesion to the negative electrode lead 32.
  • a secondary battery operates as follows when charging and discharging.
  • lithium When charging, lithium is released from the positive electrode 21 in the battery element 20 and is absorbed in the negative electrode 22 via the electrolyte.
  • lithium when discharging, lithium is released from the negative electrode 22 in the battery element 20 and is absorbed in the positive electrode 21 via the electrolyte.
  • lithium When charging and discharging, lithium is absorbed and released in an ionic state.
  • a mixture (cathode mixture) in which a cathode active material, a cathode binder, and a cathode conductive agent are mixed together is put into a solvent to prepare a paste-like cathode mixture slurry.
  • This solvent may be an aqueous solvent or an organic solvent.
  • the cathode mixture slurry is applied to both sides of the cathode current collector 21A to form the cathode active material layer 21B.
  • the cathode active material layer 21B may be compression molded using a roll press or the like. In this case, the cathode active material layer 21B may be heated, or the compression molding may be repeated multiple times. As a result, the cathode active material layer 21B is formed on both sides of the cathode current collector 21A, and thus the cathode 21 is produced.
  • the negative electrode 22 is produced by a procedure almost similar to that of the positive electrode 21 described above. Specifically, a mixture (negative electrode mixture) in which a negative electrode active material, a negative electrode binder, and a negative electrode conductive agent are mixed together is poured into a solvent to prepare a paste-like negative electrode mixture slurry, and then the negative electrode mixture slurry is applied to both sides of the negative electrode current collector 22A to form the negative electrode active material layer 22B. After this, the negative electrode active material layer 22B may be compression molded using a roll press or the like. As a result, the negative electrode active material layer 22B is formed on both sides of the negative electrode current collector 22A, and the negative electrode 22 is produced.
  • electrolyte solution An electrolyte salt is added to a solvent, whereby the electrolyte salt is dispersed or dissolved in the solvent, and an electrolyte solution is prepared.
  • the positive electrode lead 31 is connected to the positive electrode collector 21A of the positive electrode 21 using a joining method such as welding, and the negative electrode lead 32 is connected to the negative electrode collector 22A of the negative electrode 22 using a joining method such as welding.
  • the positive electrode 21 and the negative electrode 22 are stacked on top of each other with the separator 23 interposed therebetween, and the positive electrode 21, the negative electrode 22, and the separator 23 are wound to produce a wound body (not shown).
  • the wound body is then pressed using a press or the like to form a flat shape.
  • the wound body after this formation has a similar configuration to that of the battery element 20, except that the positive electrode 21, the negative electrode 22, and the separator 23 are not impregnated with the electrolyte.
  • the exterior film 10 adheresive layer/metal layer/surface protection layer
  • the exterior film 10 is folded so that the exterior films 10 face each other.
  • the outer edges of two of the opposing adhesive layers are joined to each other using an adhesive method such as heat fusion, thereby placing the roll inside the bag-shaped exterior film 10.
  • an electrolyte is injected into the bag-shaped exterior film 10, and then the outer edges of the remaining sides of the opposing fusion layers are joined together using an adhesive method such as heat fusion.
  • a sealing film 41 is inserted between the exterior film 10 and the positive electrode lead 31, and a sealing film 42 is inserted between the exterior film 10 and the negative electrode lead 32.
  • the wound body is impregnated with the electrolyte, producing the battery element 20, which is a wound electrode body, and the battery element 20 is sealed inside the bag-shaped exterior film 10, thus assembling a secondary battery.
  • the positive electrode 21 contains a positive electrode active material, and the positive electrode active material has a configuration similar to that of the positive electrode active material 100. Therefore, for the reasons described above, a high battery capacity can be obtained, and an increase in electrical resistance and a decrease in discharge capacity are suppressed even when charging and discharging are repeated, so that excellent battery characteristics can be obtained.
  • the secondary battery is a lithium-ion secondary battery
  • sufficient battery capacity can be stably obtained by utilizing the absorption and release of lithium, resulting in even greater effects.
  • the configuration of the secondary battery can be modified as appropriate, as described below. However, the series of modifications described below may be combined with each other.
  • a porous membrane separator 23 was used. However, although not specifically shown here, a laminated separator including a polymer compound layer may also be used.
  • the laminated separator includes a porous membrane having a pair of surfaces, and a polymer compound layer provided on one or both surfaces of the porous membrane. This is because the adhesion of the separator to each of the positive electrode 21 and the negative electrode 22 is improved, thereby suppressing miswinding of the battery element 20. This prevents the secondary battery from swelling even if a decomposition reaction of the electrolyte occurs.
  • the polymer compound layer includes a polymer compound such as polyvinylidene fluoride. This is because polyvinylidene fluoride has excellent physical strength and is electrochemically stable.
  • one or both of the porous film and the polymer compound layer may contain a plurality of insulating particles. This is because the plurality of insulating particles promotes heat dissipation when the secondary battery generates heat, improving the safety (heat resistance) of the secondary battery.
  • the insulating particles contain one or more types of inorganic materials and resin materials. Specific examples of inorganic materials include aluminum oxide, aluminum nitride, boehmite, silicon oxide, titanium oxide, magnesium oxide, and zirconium oxide. Specific examples of resin materials include acrylic resin and styrene resin.
  • a precursor solution containing a polymer compound and a solvent is prepared, and then the precursor solution is applied to one or both sides of a porous membrane.
  • the porous membrane may be immersed in the precursor solution.
  • multiple insulating particles may be added to the precursor solution.
  • the positive electrode 21 and the negative electrode 22 are stacked on top of each other with the separator 23 and the electrolyte layer interposed therebetween, and the positive electrode 21, the negative electrode 22, the separator 23, and the electrolyte layer are wound.
  • This electrolyte layer is interposed between the positive electrode 21 and the separator 23, and also between the negative electrode 22 and the separator 23.
  • the electrolyte layer may be interposed only between the positive electrode 21 and the separator 23, or may be interposed only between the negative electrode 22 and the separator 23.
  • This electrolyte layer contains a polymer compound as well as an electrolyte solution, and the electrolyte solution is held by the polymer compound. This is because leakage of the electrolyte solution is prevented.
  • the composition of the electrolyte solution is as described above.
  • the polymer compound contains polyvinylidene fluoride and the like.
  • a secondary battery used as a power source may be the main power source for electronic devices and electric vehicles, etc., or it may be an auxiliary power source.
  • a main power source is a power source that is used preferentially regardless of the presence or absence of other power sources.
  • An auxiliary power source may be a power source used in place of the main power source, or a power source that can be switched from the main power source.
  • secondary batteries are as follows: Electronic devices such as video cameras, digital still cameras, mobile phones, laptop computers, headphone stereos, portable radios, and portable information terminals. Storage devices such as backup power sources and memory cards. Power tools such as electric drills and power saws. Battery packs installed in electronic devices. Medical electronic devices such as pacemakers and hearing aids. Electric vehicles such as electric cars (including hybrid cars). Power storage systems such as home or industrial battery systems that store power in preparation for emergencies. In these applications, one secondary battery may be used, or multiple secondary batteries may be used.
  • the battery pack may include a single cell or a battery pack.
  • the electric vehicle is a vehicle that runs on a secondary battery as a driving power source, and may be a hybrid vehicle that also includes a driving source other than the secondary battery.
  • household electrical appliances can be used using the power stored in the secondary battery, which is a power storage source.
  • FIG. 4 shows the block diagram of a battery pack, which is an example of an application of a secondary battery.
  • the battery pack described here is a battery pack (a so-called soft pack) that uses one secondary battery, and is installed in electronic devices such as smartphones.
  • this battery pack includes a power source 51 and a circuit board 52.
  • This circuit board 52 is connected to the power source 51 and includes a positive terminal 53, a negative terminal 54, and a temperature detection terminal 55.
  • the power source 51 includes one secondary battery.
  • the positive electrode lead is connected to the positive electrode terminal 53
  • the negative electrode lead is connected to the negative electrode terminal 54.
  • This power source 51 is connected to an external power source via the positive electrode terminal 53 and the negative electrode terminal 54, and is therefore capable of being charged and discharged.
  • the circuit board 52 includes a control unit 56, a switch 57, a thermosensitive resistor (PTC element) 58, and a temperature detection unit 59.
  • the PTC element 58 may be omitted.
  • the control unit 56 includes a central processing unit (CPU) and memory, and controls the operation of the battery pack. This control unit 56 detects and controls the usage status of the power source 51 as necessary.
  • CPU central processing unit
  • the control unit 56 turns off the switch 57 to prevent charging current from flowing through the current path of the power source 51.
  • the overcharge detection voltage is not particularly limited, but is specifically 4.20V ⁇ 0.05V, and the overdischarge detection voltage is not particularly limited, but is specifically 2.40V ⁇ 0.10V.
  • Switch 57 includes a charge control switch, a discharge control switch, a charge diode, and a discharge diode, and switches between the presence and absence of a connection between power source 51 and an external device in response to an instruction from control unit 56.
  • This switch 57 includes a field effect transistor (MOSFET) that uses a metal oxide semiconductor, and the charge and discharge current is detected based on the ON resistance of switch 57.
  • MOSFET field effect transistor
  • the temperature detection unit 59 includes a temperature detection element such as a thermistor. This temperature detection unit 59 measures the temperature of the power supply 51 using the temperature detection terminal 55, and outputs the temperature measurement result to the control unit 56. The temperature measurement result measured by the temperature detection unit 59 is used when the control unit 56 performs charge/discharge control in the event of abnormal heat generation, and when the control unit 56 performs correction processing when calculating the remaining capacity.
  • [Preparation of secondary battery] 5 shows a cross-sectional structure of a test secondary battery, which is a so-called coin-type secondary battery (lithium ion secondary battery).
  • this secondary battery includes a test electrode 61, a counter electrode 62, a separator 63, an exterior cup 64, an exterior can 65, a gasket 66, and an electrolyte (not shown).
  • the test electrode 61 is housed in an exterior cup 64, and the counter electrode 62 is housed in an exterior can 65.
  • the test electrode 61 and the counter electrode 62 are stacked together with a separator 63 in between, and the electrolyte is impregnated into the test electrode 61, the counter electrode 62, and the separator 63.
  • the exterior cup 64 and the exterior can 65 are crimped together with a gasket 66, so that the test electrode 61, the counter electrode 62, and the separator 63 are sealed by the exterior cup 64 and the exterior can 65.
  • Ni 1.50 Pt 0.50 CO 3 with a purity of 99% When forming a coating material containing platinum as a constituent element as the second additional metal element, Ni 1.50 Pt 0.50 CO 3 with a purity of 99% was used as the raw material.
  • Ni 1.50 Cu 0.50 CO 3 with a purity of 99% was used as the raw material.
  • Ni 1.50 W 0.50 CO 3 with a purity of 99% was used as the raw material.
  • Ni 2 CO 3 with a purity of 99% was used as a raw material. was used.
  • Ni 1.98 Ti 0.02 CO 3 When Ni 0.99 Ti 0.01 O was used as the precursor, Ni 1.50 Ti 0.50 CO 3 was used as the raw material. When Ni 0.75 Ti 0.25 O was used as the precursor, Ni 1.50 Pt 0.50 CO 3 was used as the raw material. When Ni 0.75 Pt 0.25 O was used as the precursor, Ni 1.50 Cu 0.50 CO 3 was used as the raw material. When Ni 0.75 Cu 0.25 O was used as the precursor, Ni 1.50 W 0.50 CO 3 was used as the raw material. When Ni 2 CO 3 was used as the raw material, Ni 0.75 W 0.25 O was formed as the precursor. When used as a precursor, NiO was formed.
  • the precursor and a lithium compound (lithium oxide (Li 2 O) with a purity of 99.5%) were mixed together to obtain a mixture, which was then calcined (calcination time: 650° C. and calcination time: 24 hours) to obtain a calcined product.
  • a lithium compound lithium oxide (Li 2 O) with a purity of 99.5%
  • Li2Ni0.99Ti0.01O was formed as the fired product.
  • Ni0.75Ti0.25O was used as the precursor
  • Li2Ni0.75Ti0.25O2 was formed as the fired product .
  • Ni0.75Pt0.25O was used as the precursor
  • Li2Ni0.75Pt0.25O2 was formed as the fired product.
  • Ni0.75Cu0.25O was used as the precursor
  • Li2Cu0.75Pt0.25O2 was formed as the fired product .
  • Ni0.75W0.25O was used as the precursor
  • Li2Ni0.75W0.25O2 was formed as the fired product.
  • Li2NiO2 was formed as the fired product.
  • first lithium composite oxide having a layered rock - salt crystal structure was prepared.
  • the first lithium composite oxide was Li1.02Ni0.90Co0.05Al0.05O2 . (NCA) was used.
  • the coating material was added to the centrifugal fluidized bed granulator together with the multiple cores 110, and then granulation was performed using the centrifugal fluidized bed granulator.
  • the amount of the multiple cores 110 added was 1 kg
  • the amount of the coating material added was 45 g
  • the air volume was 0.1 m3 /min
  • the intake air temperature was 60°C
  • the exhaust air temperature was 40°C
  • the rotation speed was 150 minutes
  • the coating time was 20 minutes.
  • a powdered positive electrode active material 100 was obtained, i.e., a plurality of positive electrode active materials 100 including the central portion 110 and the coating portion 120.
  • the completed positive electrode active material 100 was analyzed to examine the composition and crystal structure of the core 110 and the composition and crystal structure of the coating 120, and the results are shown in Table 1. Details regarding the analysis procedure for the positive electrode active material 100 are as described above.
  • the average coating amount (mmol/ m2 ) of the coating portion 120 was changed by changing the mixing ratio of the precursor and the lithium compound.
  • the results of examining the average coating amount after completion of the positive electrode active material 100 are shown in Table 1. Details of the calculation procedure for the average coating amount are as described above.
  • the positive electrode active material 100, the positive electrode binder (polyvinylidene fluoride), and the positive electrode conductor (graphite) were mixed together to form a positive electrode mixture.
  • the positive electrode mixture was added to a solvent (N-methyl-2-pyrrolidone, an organic solvent), and the solvent was stirred to prepare a paste-like positive electrode mixture slurry.
  • the positive electrode mixture slurry was then applied to one side of the positive electrode current collector 21A (aluminum foil with a thickness of 15 ⁇ m) using a coating device, and the positive electrode mixture slurry was then dried to form the positive electrode active material layer 21B.
  • test electrode 61 was fabricated using the same procedure, except that the coating portion 120 was not formed.
  • a test electrode 61 was produced by the same procedure except that other compounds were used instead of the second lithium composite oxide.
  • the other compounds used were Li 2 CoO 2 having a trigonal crystal structure represented by the space group P-3m, Li 2 CoO 2 having an orthorhombic crystal structure represented by the space group Immmm, Li 2 NiO 3 having an orthorhombic crystal structure represented by the space group C2/m, and NiO having a cubic crystal structure represented by the space group Fm-3m .
  • An electrolyte salt (lithium salt, lithium hexafluorophosphate ( LiPF6 )) was added to a solvent (cyclic ethylene carbonate and chain ethylene carbonate, ethyl methyl carbonate), and the solvent was then stirred.
  • test electrode 61 was accommodated in the exterior cup 64 (SUS304 having a thickness of 200 ⁇ m), and the counter electrode 62 was accommodated in the exterior can 65 (SUS304 having a thickness of 200 ⁇ m).
  • the test electrode 61 accommodated in the exterior cup 64 and the counter electrode 62 accommodated in the exterior can 65 were stacked together via a disk-shaped separator 63 (a microporous polyethylene film having a thickness of 15 ⁇ m and a diameter of 17.5 mm) impregnated with an electrolyte.
  • the positive electrode active material layer 21B and the negative electrode active material layer 22B were opposed to each other via the separator 63.
  • the exterior cup 64 and the exterior can 65 were crimped together via a gasket 66 (a polypropylene film having a thickness of 0.3 mm).
  • a gasket 66 a polypropylene film having a thickness of 0.3 mm.
  • 0.1 C is the current value at which the battery capacity (theoretical capacity) is fully discharged in 10 hours
  • 0.005 C is the current value at which the battery capacity is fully discharged in 20 hours.
  • the secondary battery was discharged in the same environment. During discharging, a constant current of 0.1 C was discharged until the voltage reached 2.0 V.
  • the discharge capacity (discharge capacity at the 100th cycle) was measured by repeatedly charging and discharging the secondary battery in the same environment until the number of cycles reached 100.
  • the charge/discharge conditions for one cycle are as described below. That is, when evaluating the cycle characteristics, the process of charging and discharging the secondary battery based on the charge/discharge conditions described below was repeated 100 times.
  • the secondary battery was charged. In this case, it was charged at a constant current of 1C until the voltage reached 4.25V, and then it was charged at a constant voltage of 4.25V until the current reached 0.01C.
  • 1C is the current value that completely discharges the battery capacity in 1 hour
  • 0.01C is the current value that completely discharges the battery capacity in 100 hours.
  • the charged secondary battery was discharged. In this case, it was discharged at a constant current of 5C until the voltage reached 2.5V.
  • 5C is the current value at which the battery capacity is completely discharged in 0.2 hours.
  • the capacity retention values shown in Table 1 are normalized to a capacity retention value of 100 when the coating portion 120 was not formed (Comparative Example 1).
  • the electrochemical impedance (EIS) of the test electrode 61 was measured using an AC impedance method. Based on the EIS measurement results, the electrical resistance ( ⁇ ) of the test electrode 61, which is an index for evaluating the electrical resistance characteristics, was calculated. In this case, the semicircular component with a frequency in the range of 500 Hz to 1 Hz was taken as the electrical resistance of the test electrode 61.
  • the charge and discharge conditions were the same as those in the case of evaluating the cycle characteristics described above.
  • the EIS measurement device used was a multichannel potentiostat VMP-3 manufactured by Bio-Logic Science Instruments.
  • the electrical resistance values shown in Table 1 are normalized to a value of 100 when the coating portion 120 was not formed (Comparative Example 1).
  • the positive electrode active material 100 includes a core portion 110 and a coating portion 120, and when the coating portion 120 includes other compounds (Comparative Examples 2 to 5), the capacity retention rate increased slightly and, in some cases, the electrical resistance also decreased slightly.
  • the positive electrode active material 100 includes the core 110 and the coating portion 120, and the coating portion 120 includes the second lithium composite oxide (Examples 1 to 8), the capacity retention rate increased significantly and the electrical resistance also decreased significantly.
  • the coating portion 120 contained a second lithium composite oxide (Examples 1 to 8)
  • the tendency described below was observed.
  • the capacity retention rate is sufficiently increased and the electrical resistance is sufficiently decreased.
  • the positive electrode active material 100 includes a core 110 and a coating portion 120
  • the core 110 includes a first lithium composite oxide having a layered rock-salt crystal structure
  • the coating portion 120 has an orthorhombic crystal structure represented by the space group Immm and includes nickel as a constituent element
  • the capacity retention rate significantly increases and the electrical resistance significantly decreases.
  • the cycle characteristics and electrical resistance characteristics are improved, and a secondary battery with excellent battery characteristics is obtained.
  • the battery structure of the secondary battery has been described as being of a laminate film type and a coin type.
  • the battery structure of the secondary battery is not particularly limited, and may be of a cylindrical type, a square type, a button type, etc.
  • the battery element has been described as having a wound structure.
  • the structure of the battery element is not particularly limited, and may be a stacked type or a zigzag type.
  • the positive and negative electrodes are stacked on top of each other, and in the zigzag type, the positive and negative electrodes are folded in a zigzag pattern.
  • the type of electrode reactant is not particularly limited. Specifically, as described above, the electrode reactant may be other alkali metals such as sodium and potassium, or alkaline earth metals such as beryllium, magnesium and calcium. In addition, the electrode reactant may be other light metals such as aluminum.
  • the present technology can also be configured as follows.
  • the positive electrode active material is The center and a covering portion that covers a surface of the central portion, the core portion includes a first lithium composite oxide having a layered rock-salt crystal structure, the coating portion includes a second lithium composite oxide having an orthorhombic crystal structure represented by the space group Immm and containing nickel as a constituent element; Secondary battery.
  • the second lithium composite oxide contains a compound represented by formula (1): The secondary battery according to ⁇ 1>. Li2Ni1 - xMxO2 ... (1) (M is at least one of Ti, Pt, Cu, and W.
  • the M is Contains at least one of Cu and W; Or, containing at least one of Ti, Pt and Cu; The secondary battery according to ⁇ 2>.
  • the average coating amount of the coating portion is 0.01 mmol/ m2 or more and 0.05 mmol/ m2 or less.
  • ⁇ 5> It is a lithium-ion secondary battery.
  • a positive electrode active material is included,
  • the positive electrode active material is The center and a covering portion that covers a surface of the central portion, the core portion includes a first lithium composite oxide having a layered rock-salt crystal structure, the coating portion includes a second lithium composite oxide having an orthorhombic crystal structure represented by the space group Immm and containing nickel as a constituent element; Positive electrode for secondary batteries.
  • the center and a covering portion that covers a surface of the central portion, the core portion includes a first lithium composite oxide having a layered rock-salt crystal structure, the coating portion includes a second lithium composite oxide having an orthorhombic crystal structure represented by the space group Immm and containing nickel as a constituent element; Positive electrode active material for secondary batteries.

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WO2020218474A1 (ja) * 2019-04-26 2020-10-29 パナソニックＩｐマネジメント株式会社 二次電池用の正極活物質、及び二次電池
JP2023500237A (ja) * 2019-11-13 2023-01-05 エルジー エナジー ソリューション リミテッド リチウム二次電池用正極活物質及び該正極活物質の製造方法
CN112635756A (zh) * 2020-12-21 2021-04-09 国联汽车动力电池研究院有限责任公司 一种高镍正极材料及其制备方法和应用

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