Positive electrode for non-aqueous electrolyte rechargeable battery and non-aqueous electrolyte rechargeable battery

Abstract

A positive electrode for a non-aqueous electrolyte rechargeable battery and a non-aqueous electrolyte rechargeable battery are provided. The present disclosure more effectively improves a short circuit reduction or suppression effect of a non-aqueous electrolyte rechargeable battery by reducing or suppressing exposure of a positive electrode current collector when pierced by a foreign matter such as a nail. Example embodiments include a positive electrode for a non-aqueous electrolyte rechargeable battery, the positive electrode including a positive electrode current collector, a positive electrode mixture layer, an intermediate layer between the positive electrode current collector and the positive electrode mixture layer.

Description

[0001] This application claims priority to Japanese Patent Application No. 2024-142664, filed on August 23, 2024, with the Japan Patent Office, and Korean Patent Application No. 10-2025-0116059, filed on August 20, 2025, with the entire contents of each of the aforementioned priority applications are incorporated herein by reference. Technical Field

[0002] The example embodiments relate to a positive electrode for a non-aqueous electrolyte rechargeable battery, and to a non-aqueous electrolyte rechargeable battery including the positive electrode. Background Technology

[0003] Non-aqueous electrolyte rechargeable batteries, including rechargeable lithium-ion batteries, are widely used not only in large batteries (such as those used in vehicles) but also as power sources for devices such as smartphones and laptops.

[0004] Rechargeable lithium-ion batteries offer the advantage of high energy density, and because they use non-aqueous electrolytes, adequate safety measures may be expected. Furthermore, as battery size increases, ensuring safety provides a substantial advantage.

[0005] For example, when using rechargeable lithium-ion batteries (such as those powering vehicles equipped with rechargeable lithium-ion batteries), there is a risk that sharp foreign objects (such as nails) could fly into and puncture the battery during use. When a sharp foreign object (such as a nail) punctures the battery, there is a risk that the positive and negative electrodes may short-circuit. Specifically, when the positive electrode current collector and the positive electrode mixture layer deform, causing the positive electrode mixture layer to peel off from the positive electrode current collector, and the exposed positive electrode current collector comes into contact with the negative electrode, there is a concern that a short circuit with relatively low resistance may occur, leading to very high Joule heating.

[0006] Therefore, as a countermeasure to prevent rechargeable lithium-ion batteries from being exposed to foreign matter, an interlayer can be installed that can reduce or suppress the exposure of the positive electrode current collector even when the positive electrode mixture layer peels off from the positive electrode current collector due to deformation. Examples of such interlayers include those described in Japanese Patent Publication No. 2020-87647, which are installed between the positive electrode current collector and the positive electrode active material layer and include particles made of metal oxide and low Young's modulus particles made of solid electrolyte material or resin material. Summary of the Invention

[0007] However, there is room for further improvement in the short-circuit reduction or suppression effect of the aforementioned conventional intermediate layer.

[0008] This disclosure aims to more effectively improve the short-circuit reduction or suppression effect of non-aqueous electrolyte rechargeable batteries by studying the composition of the intermediate layer and the shape of the particles forming the intermediate layer, thereby more effectively reducing or suppressing the exposure of the positive electrode current collector when punctured by a foreign object (such as a nail).

[0009] In other words, this disclosure includes the following construction.

[0010] [1] A positive electrode for a non-aqueous electrolyte rechargeable battery, the positive electrode comprising: a positive electrode current collector; a positive electrode mixture layer; and an intermediate layer between the positive electrode current collector and the positive electrode mixture layer, wherein the intermediate layer comprises a first particle and a second particle, the first particle comprising boron nitride and having insulating properties, the second particle comprising at least one of a metal hydroxide and a metal oxide and a flame retardant component, the ratio of the long axis to the short axis (long axis / short axis) of the first particle being greater than or equal to about 3.0 and less than or equal to about 30, the 50% cumulative value of the particle size distribution based on the volume of the first particle being greater than or equal to about 0.01 μm and less than or equal to about 8 μm, and the 50% cumulative value of the particle size distribution based on the volume of the second particle being greater than or equal to about 0.01 μm and less than or equal to about 8 μm.

[0011] [2] The positive electrode for a non-aqueous electrolyte rechargeable battery as described in [1], wherein the first particle is made of or includes boron nitride.

[0012] [3] According to the positive electrode for a non-aqueous electrolyte rechargeable battery described in [1] or [2], the amount of P2 desorbed from the second particle at about 80°C to about 1400°C, as determined by thermal desorption gas mass spectrometry (TDS-MS), can be greater than or equal to about 200 × 10⁻⁶. -6 mol / g and less than or equal to approximately 2500 × 10 -6 The amount of H₂O desorbed from the second particle at approximately 80 °C to approximately 200 °C, as determined by TDS-MS, can be greater than or equal to approximately 50 × 10⁻⁶ mol / g. - 6 mol / g and less than or equal to approximately 1000 × 10 -6 mol / g, and the ratio of the amount of P2 desorbed to the amount of H2O desorbed (MS1 / MS2) can satisfy the following equation (1).

[0013] 0.5≤(MS1 / MS2)≤10 Equation (1).

[0014] [4] The positive electrode for a non-aqueous electrolyte rechargeable battery as described in any one of [1] to [3], wherein, in the second particle, the surface or interior of at least one of a metal hydroxide and a metal oxide may be modified with a flame retardant.

[0015] [5] The positive electrode for a non-aqueous electrolyte rechargeable battery as described in any one of [1] to [4], wherein the metal hydroxide may include at least one of kaolinite, pseudoboehmite, boehmite and aluminum hydroxide.

[0016] [6] The positive electrode for a non-aqueous electrolyte rechargeable battery as described in any of [1] to [5], wherein the metal oxide may be or includes active aluminum oxide.

[0017] [7] The positive electrode for a non-aqueous electrolyte rechargeable battery as described in [4], wherein the flame retardant may include at least one of phosphoric acid, phosphate ester, phosphonic acid, phosphonate ester, hypophosphonic acid and hypophosphonate ester.

[0018] [8] A positive electrode for a non-aqueous electrolyte rechargeable battery as described in any of [1] to [7], wherein the thickness of the intermediate layer may be greater than or equal to about 0.1 μm and less than or equal to about 10 μm.

[0019] [9] The positive electrode for a non-aqueous electrolyte rechargeable battery as described in any of [1] to [8], wherein the intermediate layer may further include a conductive agent.

[0020]

[10] The positive electrode for a non-aqueous electrolyte rechargeable battery as described in [9], wherein the conductive agent may be at least one of carbon nanofibers and carbon black.

[0021]

[11] A non-aqueous electrolyte rechargeable battery, comprising a positive electrode, a negative electrode, a separator and a non-aqueous electrolyte, wherein the positive electrode is a positive electrode for a non-aqueous electrolyte rechargeable battery as described in any one of [1] to

[10] .

[0022] According to this disclosure, the first particle includes boron nitride, and the aspect ratio (major axis / minor axis) of the first particle is set to be greater than or equal to about 3.0 and less than or equal to about 30, thereby including that the intermediate layer of the first particle can be significantly deformed along the surface shape of the positive electrode current collector when punctured by a foreign object (such as a nail), and can reduce or suppress the exposure of the positive electrode current collector.

[0023] Boron nitride can capture reactive oxygen species, thereby reducing or inhibiting electrolyte decomposition reactions and thus lowering or suppressing battery temperature rise.

[0024] Because the intermediate layer also includes a second particle containing at least one of metal hydroxide and metal oxide, as well as a flame retardant component, the temperature rise of the battery can be further reduced or suppressed, and safety can be substantially improved by reducing or suppressing the endothermic reaction of the electrolyte caused by metal hydroxide or metal oxide and the decomposition reaction caused by free radical capture of the flame retardant component. Attached Figure Description

[0025] Figure 1 This is a schematic diagram illustrating the overall structure of a non-aqueous electrolyte rechargeable battery according to some example embodiments.

[0026] Figure 2 This is a graph showing the results of confirming the presence or absence of an exothermic peak at 150°C or lower in the example and comparative examples of this disclosure, under the coexistence of the electrolyte and the second particle. Detailed Implementation

[0027] Hereinafter, exemplary embodiments are described in detail to enable those skilled in the art to readily implement them. However, this disclosure may be implemented in many different forms and is not to be construed as limited to the exemplary embodiments set forth herein. The terminology used herein is for describing exemplary embodiments and is not intended to limit this disclosure.

[0028] Unless the context clearly indicates otherwise, singular expressions include plural expressions. As used herein, "combination thereof" means mixtures, laminates, complexes, copolymers, alloys, blends, reaction products, etc. It should be understood here that terms such as "comprising," "including," or "having" are intended to indicate the presence of the features, quantities, steps, elements, or combinations thereof embodied, but do not preclude the possibility of the presence or addition of one or more other features, quantities, steps, elements, or combinations thereof.

[0029] In the accompanying drawings, for clarity, the thickness of layers, films, panels, regions, etc., is exaggerated, and the same reference numerals denote the same elements throughout the specification. It is understood that when an element (such as a layer, film, region, or substrate) is referred to as being "on" another element, the element may be directly on the other element, or there may be intervening elements therein. Conversely, when an element is referred to as being "directly on" another element, there are no intervening elements. Furthermore, the term "layer" here includes not only shapes formed across the entire surface when viewed in plan view, but also shapes formed on a portion of the surface.

[0030] Additionally, particle size can be the average particle size and can be measured using methods known to those skilled in the art (e.g., particle size analyzer, or, for example, transmission electron microscopy or scanning electron microscopy images). Alternatively, the average particle size value can be obtained by using dynamic light scattering, performing data analysis, counting the number of particles in each particle size range, and calculating the average particle size from the counted particles. Unless otherwise defined, the average particle size can represent the diameter (D) of particles having a cumulative volume of 50% of the particle size distribution. 50 As used herein, unless otherwise defined, the average particle size represents the diameter of the particles having a cumulative volume of 50% of the total volume in a particle size distribution obtained by randomly measuring the size (diameter or length of the major axis) of approximately 20 particles in a scanning electron microscope image. 50 ).

[0031] Here, "or" is not to be interpreted as exclusive; for example, "A or B" is interpreted as including A, B, A+B, etc. "Metal" is interpreted as including the concepts of common metals, transition metals, and quasi-metals (semi-metals). When the terms "about" or "substantially" are used in conjunction with numerical values ​​in this specification, it is intended that the relevant numerical values ​​include a tolerance of ±10% around the stated value. When a range is specified, the range includes all values ​​in increments such as 0.1%. Below, the construction of a non-aqueous electrolyte rechargeable battery according to some example embodiments is described.

[0032] 1. Basic structure of non-aqueous electrolyte rechargeable batteries Figure 1 This is a cross-sectional view showing a non-aqueous electrolyte rechargeable battery 100. (See diagram below.) Figure 1 As shown, the non-aqueous electrolyte rechargeable battery 100 according to the example embodiment is a rechargeable lithium-ion battery including a positive electrode 1, a negative electrode 2, a separator 3 between the positive electrode 1 and the negative electrode 2, a non-aqueous electrolyte 4, and a container 5 that houses the above features therein.

[0033] The non-aqueous electrolyte rechargeable battery 100 can be, for example, cylindrical, square, laminated, or button-shaped.

[0034] 1-1, Positive Electrode In various examples, the positive electrode 1 includes a positive electrode current collector 11 and a positive electrode mixture layer 12 on the positive electrode current collector 11.

[0035] The positive electrode current collector 11 can be or includes any material, as long as the material is a conductor, and is, for example, plate-shaped or thin, and can be made of or include at least one of aluminum, stainless steel, nickel-plated steel, etc.

[0036] The positive electrode mixture layer 12 may include at least a positive electrode active material, and may also include a conductive agent and a positive electrode binder.

[0037] The positive electrode active material can be or includes, for example, a transition metal oxide or solid solution oxide comprising lithium, provided that the positive electrode active material is or includes a material capable of electrochemically inserting and deintercalating lithium ions. The positive electrode active material can be, for example, in particulate form. Examples of transition metal oxides comprising lithium include Li. 1.0 Ni 0.88 Co 0.1 Al 0.01 Mg 0.01 O2, etc. In addition, transition metal oxides including lithium can also include Li·Co composite oxides (such as LiCoO2), Li·Ni·Co-Mn composite oxides (such as LiNi...). x Co y Mn z Examples of solid solution oxides include, for example, O2), Li-Ni composite oxides (such as LiNiO2), or Li-Mn composite oxides (such as LiMn2O4). Examples of solid solution oxides may include at least Li... a Mn x Co y Ni z O2 (1.150≤a≤1.430, 0.45≤x≤0.6, 0.10≤y≤0.15, 0.20≤z≤0.28) or LiMn 1.5 Ni 0.5 O4. There are no particular restrictions on the content (ratio) of the positive electrode active material, as long as the content or ratio is suitable for the positive electrode mixture layer 12 of the non-aqueous electrolyte rechargeable battery 100. In addition, these compounds can be used alone or in various mixtures.

[0038] There are no particular limitations on the material of the conductive agent, as long as it increases the conductivity of the positive electrode 1. Examples of conductive agents may include at least one of carbon black, natural graphite, artificial graphite, fibrous carbon, and flake carbon. Examples of carbon black may include, for example, furnace black, channel black, thermal black, Ketjen black, and acetylene black.

[0039] Examples of fibrous carbon can include carbon nanotubes and carbon nanofibers, while examples of sheet-like carbon include graphene and the like.

[0040] Based on the total amount of the positive electrode mixture layer 12, the content of the conductive agent in the positive electrode mixture layer 12 can be, for example, greater than or equal to about 0.1 wt% and less than or equal to about 5 wt%, or greater than or equal to about 0.5 wt% and less than or equal to about 3 wt%, to achieve both conductivity and battery capacity.

[0041] The positive electrode binder may include, for example, a fluororesin (such as polyvinylidene fluoride), an ethylene resin (such as at least one of styrene-butadiene rubber, ethylene-propylene-diene terpolymer, acrylonitrile-butadiene rubber, fluororubber, polyvinyl acetate, polymethyl methacrylate, polyethylene, and polyvinyl alcohol), carboxymethyl cellulose, carboxymethyl cellulose derivatives (such as salts of carboxymethyl cellulose), nitrocellulose, etc. The positive electrode binder may be or include any material capable of binding the positive electrode active material and the conductive agent to the positive electrode current collector 11.

[0042] 1-2. Negative electrode In various examples, the negative electrode 2 includes a negative electrode current collector 21 and a negative electrode mixture layer 22 on the negative electrode current collector 21. The negative electrode current collector 21 may be any conductor material, and may be plate-shaped or thin, and made of or include at least one of copper, stainless steel, nickel-plated steel, etc.

[0043] The negative electrode mixture layer 22 may include a negative electrode active material, and may also include a conductive agent and a negative electrode binder.

[0044] The negative electrode active material is configured to electrochemically intercalate and deintercalate lithium ions, and may be or include, for example, a graphite active material (artificial graphite, natural graphite, a mixture of artificial graphite and natural graphite, natural graphite coated with artificial graphite), a Si-based active material or a Sn-based active material (e.g., fine particles of silicon (Si) or tin (Sn) or a mixture of their oxides and a graphite active material, fine particles of silicon or tin, an alloy including silicon or tin as a matrix material), metallic lithium, a titanium oxide compound (such as Li4Ti5O 12 ) and lithium nitride, etc. At least one of the above examples may be used as the negative electrode active material, or two or more of the above examples may be used in combination. For example, the oxide of silicon may be represented by SiO x (0 < x ≤ 2).

[0045] The material of the conductive agent is configured to increase the conductivity of the negative electrode 2, and may be or include, for example, the same conductive agent as described in part 1-1 above.

[0046] Based on the total weight of the negative electrode mixture layer 22, the content of the conductive agent in the negative electrode mixture layer 22 may be greater than or equal to about 0.1 wt% and less than or equal to about 5 wt%, or greater than or equal to about 0.5 wt% and less than or equal to about 3 wt% to achieve both conductivity and battery capacity.

[0047] The negative electrode binder can bond the negative electrode active material and the conductive agent to the negative electrode current collector 21. The negative electrode binder can be or include at least one of the following: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyacrylic acid (PAA), styrene-butadiene copolymer (SBR), carboxymethyl cellulose (CMC) metal salts, etc. The binder can be used alone or in a mixture of two or more binders.

[0048] 1-3. Diaphragm The separator 3 can be or includes any separator suitable for use in rechargeable lithium-ion batteries. The separator 3 can be or includes porous membranes, nonwoven fabrics, etc., exhibiting desired, improved, or advantageous high-rate discharge performance, either alone or in combination. The resin constituting or included in the separator 3 can be or includes, for example, polyolefin resins (such as polyethylene, polypropylene, etc.), polyester resins (such as polyethylene terephthalate, polybutylene terephthalate, etc.), polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-perfluorovinyl ether copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-hexafluoroacetone copolymer, vinylidene fluoride-ethylene copolymer, vinylidene fluoride-propylene copolymer, vinylidene fluoride-trifluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-ethylene-tetrafluoroethylene copolymer, etc. The porosity of the separator 3 can be, for example, the porosity of separators in conventional rechargeable lithium-ion batteries.

[0049] The separator 3 may also include a surface layer covering the surface of the porous membrane or nonwoven fabric described above. The surface layer may include an adhesive for fixing the battery element by adhering it to the electrodes. Examples of the adhesive may include at least one of, for example, vinylidene fluoride-hexafluoropropylene copolymer, acid-modified products of vinylidene fluoride polymers, and styrene-(meth)acrylate copolymers.

[0050] 1-4. Non-aqueous electrolytes As the non-aqueous electrolyte 4, the same non-aqueous electrolyte as that commonly used in rechargeable lithium-ion batteries can be used. The non-aqueous electrolyte 4 has a composition in which an electrolyte salt is included in a non-aqueous solvent, and the non-aqueous solvent is a solvent for the electrolyte. Examples of the non-aqueous solvent may include cyclic carbonates (such as at least one of propylene carbonate, ethylene carbonate, butylene carbonate, chloroethylene carbonate, fluoroethylene carbonate, and vinylene carbonate), cyclic esters (such as γ-butyrolactone and γ-valerolactone), chain carbonates (such as at least one of dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate), chain esters (such as methyl formate, methyl acetate, methyl butyrate, ethyl propionate, and propyl propionate), ethers (such as tetrahydrofuran or its derivatives, 1,3-dioxane, 1,4-dioxane, 1,2-dimethoxyethane, 1,4-dibutoxyethane, methyl diglycol dimethyl ether, ethylene glycol monopropyl ether, or propylene glycol monopropyl ether), nitriles (such as acetonitrile and benzonitrile), dioxolane or its derivatives, thioethane, sulfolane, sultone or its derivatives, and they can be used alone or as a mixture of two or more solvents. On the other hand, when mixing two or more types of non-aqueous solvents, the mixing ratio of each non-aqueous solvent can be a mixing ratio that can be used in conventional or other rechargeable lithium-ion batteries.

[0051] Examples of the electrolyte salt may include: inorganic ionic salts, including at least one of, for example, lithium (Li), sodium (Na), and potassium (K), such as LiClO4, LiBF4, LiAsF6, LiPF6, LiPF 6-x (C n F 2n+1 ) x [provided that 1 < x < 6 and n = 1 or 2], LiSCN, LiBr, LiI, Li2SO4, Li2B 10 Cl 10NaClO4, NaI, NaSCN, NaBr, KClO4, KSCN; or organic ionic salts, such as LiCF3SO3, LiN(CF3SO2)2, LiN(C2F5SO2)2, LiN(CF3SO2)(C4F9SO2), LiC(CF3SO2)3, LiC(C2F5SO2)3, (CH3)4NBF4, (CH3)4NBr, (C2H5)4NClO 4. Lithium stearate, lithium octyl sulfonate, lithium dodecylbenzene, etc., can be used alone or in mixtures of two or more types of ionic compounds. For example, the concentration of the electrolyte salt can be the same as that of the electrolyte salt used in conventional rechargeable lithium-ion batteries. In some exemplary embodiments, it is desirable to use a non-aqueous electrolyte 4 comprising the above-mentioned lithium compounds (electrolyte salts) at a concentration greater than or equal to about 0.8 mol / L and less than or equal to about 1.5 mol / L.

[0052] On the other hand, various additives can be added to the non-aqueous electrolyte 4. Examples of such additives may include at least one of the following: negative electrode additives, positive electrode additives, ester additives, carbonate additives, sulfate ester additives, phosphate ester additives, borate ester additives, acid anhydride additives, and electrolyte additives. One of the above additives can be added to the non-aqueous electrolyte, and multiple types of additives can be added.

[0053] 2. Construction of a non-aqueous electrolyte rechargeable battery according to an example embodiment The following describes the characteristic construction of a non-aqueous electrolyte rechargeable battery 100 according to some example embodiments.

[0054] The positive electrode 1 of the non-aqueous electrolyte rechargeable battery 100 according to the example embodiment has an intermediate layer 13 between the positive electrode current collector 11 and the positive electrode mixture layer 12.

[0055] The intermediate layer 13 includes, for example, at least one of a first particle, a second particle, a conductive agent, and an adhesive for the intermediate layer.

[0056] The first particle is an insulating particle comprising boron nitride. The first particle may have boron nitride as its main component, or may be made of boron nitride. The main component refers to the component included in the particle in the largest quantity, for example, a component included in the total particle at a proportion greater than or equal to about 50% by mass, greater than or equal to about 70% by mass, or greater than or equal to about 90% by mass. In this example embodiment, as an example of the first particle, a particle made of boron nitride is used.

[0057] The first particle has a length-to-thickness ratio (long axis / short axis) of about 3.0 and less than or equal to about 30 (e.g., greater than or equal to about 3.0 and less than or equal to about 15).

[0058] As described herein, the major axis is the maximum diameter of the particle, and the minor axis is the minimum diameter of the particle. For example, the particle may be in the form of a sheet, where the major axis may refer to the longest diameter of the sheet, and the minor axis may refer to the thickness of the sheet.

[0059] Methods for measuring the major and minor axes can include, for example, calculating D. 50 The method or the method of calculating the major axis and / or minor axis through scanning electron microscope images, D 50 This is 50% of the cumulative value of particle size distribution based on particle size-volume obtained by laser diffraction / scattering. One of the above measurement methods can be used alone, or both can be used for a more accurate approach. For example, when the particles are flake-like and too thin to be calculated using D... 50 When accurately measuring thickness using the method described above, D can be used. 50 The major axis can be measured, and the minor axis can be obtained through scanning electron microscope images.

[0060] In the example embodiment, sheet-like particles can be used as an example of the first particle, but the shape of the first particle can be any shape that satisfies the above-mentioned length-to-thickness ratio condition, and can be any of the following shapes: spherical, sheet-like, columnar, and needle-like.

[0061] In the particle size distribution obtained by laser diffraction / scattering based on the volume of the first particle, D is the cumulative value of 50% of the particle size distribution based on particle size volume. 50 It can be greater than or equal to about 0.01 μm and less than or equal to about 8 μm, for example, greater than or equal to about 0.05 μm and less than or equal to about 7 μm, or greater than or equal to about 0.1 μm and less than or equal to about 6 μm.

[0062] When the entire intermediate layer 13 is 100% by mass, the amount of the first particle in the intermediate layer 13 can be greater than or equal to about 40% by mass and less than or equal to about 90% by mass, for example, greater than or equal to about 50% by mass and less than or equal to about 80% by mass, or greater than or equal to about 60% by mass and less than or equal to about 70% by mass.

[0063] The second particle comprises at least one of a metal hydroxide and a metal oxide, as well as a flame retardant component.

[0064] The second particle may be or include, for example, a composite particle formed by mixing at least one of metal hydroxide particles and metal oxide particles with a flame retardant component and heating.

[0065] The composite particles used in exemplary embodiments are described below.

[0066] The aforementioned composite particles are formed by heating and compounding at least one of endothermic metal hydroxide particles and metal oxide particles with a flame retardant component having free radical scavenging capabilities via an endothermic reaction. Composite particles are complexes in which at least one of the metal hydroxide particles and metal oxide particles is mixed with the flame retardant component as uniformly or substantially uniformly as possible. Composite particles can be formed, for example, by aggregating multiple particles of at least one type of metal hydroxide particles and metal oxide particles including the flame retardant component on their surface and interior. Here, the term composite means, for example, a state in which multiple particles are formed as a single block by chemically bonding with the flame retardant component via one or more functional groups (e.g., hydroxyl and phosphate groups) included on and inside their surface and interior. Here, chemical bonding includes not only covalent bonding but also various types of bonding (such as ionic bonding, coordination bonding, and metallic bonding). The bonding state between particles can be confirmed by, for example, X-ray photoelectron spectroscopy.

[0067] Furthermore, the Brunauer-Emmett-Teller (BET) specific surface area of ​​the composite particles, calculated via adsorption isotherms measured by adsorbing nitrogen onto the composite particles, can be greater than or equal to approximately 8 m². 2 / g and less than or equal to approximately 80m 2 / g (e.g., greater than or equal to about 10m) 2 / g and less than or equal to approximately 75m 2 / g, or greater than or equal to approximately 15m 2 / g and less than or equal to approximately 75m 2 / g).

[0068] There are no particular limitations on the metal hydroxides and metal oxides, as long as they are or include endothermic materials capable of inducing an endothermic reaction. Examples of metal hydroxides and metal oxides may include, for instance, aluminum hydroxide, pseudoboehmite, boehmite, activated alumina, and kaolinite. These may be used alone or in combination of two or more of the above types of materials.

[0069] Based on the total composite particles (100% by mass), the amounts of metal hydroxide particles and metal oxide particles in the composite particles can be in the range of greater than or equal to about 1% by mass and less than or equal to about 60% by mass, greater than or equal to about 5% by mass and less than or equal to about 50% by mass, or greater than or equal to about 10% by mass and less than or equal to about 40% by mass, respectively. When multiple types of particles are used together, the amount refers to the total content of metal hydroxide particles and metal oxide particles.

[0070] The flame retardant component can be any compound having free radical scavenging capabilities to, for example, capture free radicals (such as oxygen free radicals) generated in the positive electrode mixture layer, and can be derived, for example, from one or more flame retardants such as or including at least one of phosphoric acid, phosphate esters, phosphonic acid, phosphonate esters, hypophosphonic acid, and hypophosphonate esters, which can form a functional group containing phosphorus (P) by combining with at least one of metal hydroxide particles and metal oxide particles. Examples of phosphate esters can include at least one of phenyl phosphate, diphenyl phosphate, and triphenyl phosphate. Examples of phosphonate esters can include at least one of phenylphosphonic acid and methylphosphonic acid. Examples of hypophosphonate esters can include methylhydantoin.

[0071] Based on the entire composite particle (100% by mass), the content of phosphorus (P), the total content of phosphorus and boron (B), or the total content of phosphorus and bromine (Br) in the composite particle, measured by inductively coupled plasma atomic emission spectrometry (ICP-AES), can be in the range of greater than or equal to about 18% by mass and less than or equal to about 30% by mass. The content of each of these elements or the total content can be greater than or equal to about 18% by mass and less than or equal to about 25% by mass.

[0072] The content of phosphorus (P) in the composite particles can be greater than or equal to about 5% by mass and less than or equal to about 30% by mass, or greater than or equal to about 8% by mass and less than or equal to about 30% by mass.

[0073] The content of boron (B) in the composite particles can be 0, but can be greater than or equal to about 1% by mass and less than or equal to about 25% by mass, or greater than or equal to about 5% by mass and less than or equal to about 15% by mass.

[0074] The Br (bromine) content in the composite particles can be 0, but can be greater than or equal to about 1% by mass and less than or equal to about 25% by mass, or greater than or equal to about 5% by mass and less than or equal to about 10% by mass.

[0075] On the other hand, the content of Al (aluminum) in the composite particles, as measured by, for example, ICP-AES, can be 0, but can be greater than or equal to about 1% by mass and less than or equal to about 30% by mass, greater than or equal to about 3% by mass and less than or equal to about 20% by mass, or greater than or equal to about 5% by mass and less than or equal to about 15% by mass.

[0076] Composite particles can have various amounts of desorbed gas within the following ranges due to various modifying groups.

[0077] When the composite particles are heated from about 80°C to about 1400°C, the amount of P2 gas desorbed from the composite particles (referred to as MS1), as measured by thermal desorption gas mass spectrometry (TDS-MS), can be greater than or equal to about 5 × 10⁻⁶. -6 mol / g and less than or equal to approximately 5000 × 10⁻⁶ -6 mol / g (e.g., greater than or equal to about 200 × 10⁻⁶) -6 mol / g and less than or equal to approximately 2500 × 10 -6 mol / g, greater than or equal to approximately 500 × 10 -6 mol / g and less than or equal to approximately 2000 × 10⁻⁶ -6 mol / g, greater than or equal to approximately 600 × 10 - 6 mol / g and less than or equal to approximately 1900 × 10 -6 mol / g, or greater than or equal to approximately 700 × 10⁻⁶ -6 mol / g and less than or equal to approximately 1800 × 10 -6 mol / g).

[0078] For example, when the composite particles are heated from about 80°C to about 200°C, the amount of H2O gas desorbed from the composite particles (referred to as MS2), as measured by TDS-MS, can be greater than or equal to about 50 × 10⁻⁶. -6 mol / g and less than or equal to approximately 6000 × 10 - 6 mol / g, greater than or equal to approximately 50 × 10 -6 mol / g and less than or equal to approximately 1000 × 10 -6 mol / g, greater than or equal to approximately 100 × 10 -6 mol / g and less than or equal to approximately 950 × 10 -6 mol / g, or greater than or equal to approximately 200 × 10-6 mol / g and less than or equal to approximately 900 × 10 -6 mol / g.

[0079] Furthermore, the ratio of the amount of desorbed gas (MS1 / MS2) can be greater than or equal to about 0.1 and less than or equal to about 10, greater than or equal to about 0.5 and less than or equal to about 10, greater than or equal to about 0.7 and less than or equal to about 5.0, or greater than or equal to about 0.8 and less than or equal to about 3.0. By ensuring that the ratio of the amount of desorbed gas (MS1 / MS2) meets the aforementioned range, a better balance can be achieved between reducing or suppressing the temperature rise caused by increasing the content of flame retardant components in the composite particles and battery performance.

[0080] Increasing the phosphorus content in the composite particles improves the effect of reducing or suppressing temperature rise inside the battery. On the other hand, when the amount of flame retardant (such as phosphoric acid or phosphonic acid) added is increased to increase the phosphorus content, the hydrophilicity of the composite particles increases, which may make it challenging to uniformly mix the composite particles in the slurry used to form the intermediate layer. In the embodiments, not only by using phosphoric acid and phosphonic acid with high phosphorus content, but also by using flame retardants with hydrophobic groups (such as phosphate esters and phosphonate esters), it is possible to reduce or suppress the excessive increase in hydrophilicity while increasing the phosphorus content. The content of hydrophobic groups in the composite particles is evaluated by the amount of various desorbed gases from the various hydrophobic groups in the composite particles, and thus the amount of various desorbed gases can meet the following ranges.

[0081] When the composite particles are heated from about 80°C to about 1400°C, the amount of CH4 gas desorbed from the composite particles, as measured by TDS-MS (referred to as MS3), can be 0 mol / g, but can be greater than 0 mol / g and less than or equal to about 3000 × 10⁻⁶. -6 mol / g, and in the example embodiments, this amount may also be greater than or equal to about 3 × 10⁻⁶ mol / g. -6 mol / g and less than or equal to approximately 400 × 10 - 6 mol / g, greater than or equal to approximately 40 × 10 -6 mol / g and less than or equal to approximately 350 × 10 -6 mol / g, or greater than or equal to approximately 50 × 10 -6 mol / g and less than or equal to approximately 300 × 10 -6 mol / g.

[0082] The amount of desorbed CH3OH measured in the same manner (referred to as MS4) can be 0 mol / g, but can be greater than 0 mol / g and less than or equal to approximately 6000 × 10⁻⁶. -6mol / g, and in example embodiments, this amount may also be greater than or equal to about 500 × 10⁻⁶ mol / g. -6 mol / g and less than or equal to approximately 2500 × 10 -6 mol / g, greater than or equal to approximately 600 × 10 -6 mol / g and less than or equal to approximately 2450 × 10 -6 mol / or greater than or equal to approximately 700 × 10 -6 mol / g and less than or equal to approximately 2400 × 10⁻⁶ -6 mol / g.

[0083] When the composite particles are modified with functional groups including phenyl groups among the hydrophobic groups, the composite particles can be more dispersed in the solvent when the slurry is made using a non-aqueous solvent such as N-methyl-2-pyrrolidone (NMP).

[0084] Therefore, the amount of C6H6 desorbed from the above composite particles at approximately 80°C to approximately 1400°C, as measured by TDS-MS (referred to as MS5), can be 0 mol / g, but can be greater than 0 mol / g and less than or equal to approximately 5000 × 10⁻⁶. -6 mol / g, in the example embodiment, this amount may also be greater than or equal to about 100 × 10⁻⁶ mol / g. -6 mol / g and less than or equal to approximately 2500 × 10 -6 mol / g, greater than or equal to approximately 300 × 10 -6 mol / g and less than or equal to approximately 2400 × 10⁻⁶ -6 mol / g, or greater than or equal to approximately 600 × 10 -6 mol / g and less than or equal to approximately 2300 × 10 -6 mol / g.

[0085] The shape of the second particle is not particularly restricted, but it can be spherical. In the particle size distribution obtained by laser diffraction / scattering based on the volume of the second particle, D is the cumulative value of 50% of the particle size distribution based on particle size volume. 50 The particle size can be greater than or equal to about 0.01 μm and less than or equal to about 8 μm, for example, greater than or equal to about 0.05 μm and less than or equal to about 5 μm, or greater than or equal to about 0.1 μm and less than or equal to about 3 μm. The particle size of the composite particles can be controlled by the preparation conditions of the composite particles. For example, when preparing composite particles, increasing the temperature or stirring speed tends to make the particle size of the composite particles smaller. For example, the particle size of the composite particles can also be smaller than the particle size of the starting material used as a metal hydroxide or metal oxide.

[0086] Based on 100% by mass of intermediate layer 13, the amount of the second particle in intermediate layer 13 may be greater than or equal to about 1% by mass and less than or equal to about 40% by mass, greater than or equal to about 5% by mass and less than or equal to about 30% by mass, or greater than or equal to about 10% by mass and less than or equal to about 20% by mass.

[0087] Conductive agents include at least one of, for example, carbon black, natural graphite, artificial graphite, fibrous carbon, and flake carbon.

[0088] Examples of carbon black may include furnace black, channel black, thermal black, Ketjen black, and acetylene black.

[0089] From the perspective that conductive channels can be formed even in small amounts, it may be more desirable to use fibrous carbon (e.g., carbon nanofibers) as described in the examples above.

[0090] Based on 100% by mass of intermediate layer 13, the amount of conductive agent in intermediate layer 13 may be greater than or equal to about 0.01% by mass and less than or equal to about 10% by mass, greater than or equal to about 0.5% by mass and less than or equal to about 5% by mass, or greater than or equal to about 1% by mass and less than or equal to about 3% by mass.

[0091] There are no particular limitations on the adhesive used for the intermediate layer, and it can be any adhesive that can bond the components constituting the intermediate layer 13 to each other and also bond the intermediate layer 13 to the positive electrode current collector 11.

[0092] Examples of adhesives used for intermediate layers may include at least one of fluorinated resins (such as polyvinylidene fluoride), ethylene-containing resins (such as styrene-butadiene rubber, ethylene-propylene-diene terpolymer, acrylonitrile-butadiene rubber, fluororubber, polyvinyl acetate, polymethyl methacrylate, polyethylene, and polyvinyl alcohol), carboxymethyl cellulose, carboxymethyl cellulose derivatives (e.g., salts of carboxymethyl cellulose), and nitrocellulose.

[0093] Based on 100% by mass of intermediate layer 13, the amount of adhesive used for intermediate layer 13 may be greater than or equal to about 0.1% by mass and less than or equal to about 30% by mass, greater than or equal to about 5% by mass and less than or equal to about 25% by mass, or greater than or equal to about 10% by mass and less than or equal to about 20% by mass.

[0094] The thickness of the intermediate layer 13 can be greater than or equal to about 0.1 μm and less than or equal to about 10 μm, greater than or equal to about 0.5 μm and less than or equal to about 8 μm, or greater than or equal to about 1 μm and less than or equal to about 5 μm.

[0095] By setting the thickness of the intermediate layer 13 to be greater than or equal to approximately 0.1 μm, sufficient short-circuit reduction or prevention effects and heat generation reduction or suppression effects can be achieved. Furthermore, by setting the thickness of the intermediate layer 13 to be less than or equal to approximately 10 μm, the increase in resistance and the decrease in battery energy density caused by the intermediate layer 13 can be reduced or suppressed. The thickness of the intermediate layer 13 can be measured, for example, in the following order: First, a profile sample is prepared by cutting the positive electrode 1 along its thickness direction using a profile sample preparation apparatus (such as a profile polisher). The prepared profile sample is observed using a scanning electron microscope (SEM), and the thickness of the intermediate layer 13 is calculated from the SEM image. For example, the thickness is measured at at least three locations in the profile sample, including the center and both ends of the intermediate layer 13, and the average value is taken as the thickness of the intermediate layer 13.

[0096] On the other hand, the amount of the first and second particles in the intermediate layer 13 can be measured by the following method.

[0097] First, a cross-sectional specimen comprising the intermediate layer 13 is prepared using a cross-sectional specimen preparation apparatus (such as a cross-sectional polisher). SEM-EDS observations are performed at at least three locations, including the center and both ends of the cross-sectional specimen, to quantify the mass of the major element (such as boron) included in the cross-sectional specimen. Based on the results of the SEM-EDS observations, the molecular structures of the first and second particles constituting the intermediate layer 13 can also be determined. Based on the specified molecular structures and the mass of the major element (such as boron), the masses of the first and second particles included in the cross-sectional specimen are calculated. Based on the masses of the first and second particles thus prepared and the mass of the cross-sectional specimen, the amount of the first and second particles in the intermediate layer 13 can be calculated.

[0098] The equipment and conditions used for measurement can be described as follows.

[0099] Measurement equipment: SM-7800F electric field emission scanning electron microscope (FE-SEM, JEOL Ltd.) Energy Dispersion Analyzer JED100mm (EDS, manufactured by NEC). Accelerating voltage: 4kV 3. Method for manufacturing a non-aqueous electrolyte rechargeable battery according to an example embodiment. Hereinafter, a method for manufacturing a non-aqueous electrolyte rechargeable battery 100 according to an example embodiment is described.

[0100] 3-1. Manufacturing method of positive electrode The positive electrode 1 is manufactured as follows: First, a mixture of first particles, second particles, a conductive agent, and a binder for the intermediate layer in desired proportions is dispersed in a suitable solvent to form an intermediate layer slurry. Then, the intermediate layer slurry is coated onto one or both surfaces of the positive electrode current collector 11 and dried to form an intermediate layer 13. Next, a positive electrode slurry is formed by dispersing a mixture of positive electrode active material, a conductive agent, and a positive electrode binder in desired proportions into a solvent for the positive electrode slurry. Then, the positive electrode slurry is coated onto the surface of the intermediate layer 13 formed as described above and dried to form a positive electrode mixture layer 12. The positive electrode mixture layer 12 is pressed using a press to obtain a desired density. Thus, the positive electrode 1 is manufactured. On the other hand, there are no particular limitations on the coating method for each layer. Coating methods may include, for example, a doctor blade coating method, a gravure coating method, a reverse roll coating method, a slot die coating method, etc. Each of the following coating processes is also performed by the same method.

[0101] On the other hand, the composite particles used as the second particles in the example embodiment can be prepared by mixing at least one of metal hydroxide particles and metal oxide particles with a flame retardant and heating.

[0102] For example, a dispersion of at least one of metal hydroxide particles and metal oxide particles with a flame retardant in a suitable solvent is heated to a temperature greater than or equal to about 40°C and less than or equal to about 100°C, at which temperature the reaction is carried out for a duration greater than or equal to about 1 hour and less than or equal to about 48 hours, and then filtered through filter paper to obtain composite particles.

[0103] The solvent may include water, and may include mixtures of water and alcoholic organic solvents (such as ethanol or 2-propanol). The heating temperature may be greater than or equal to about 60°C and less than or equal to about 80°C, and the heating time (reaction time) may be greater than or equal to about 5 hours and less than or equal to about 30 hours.

[0104] The cumulative value of 50% of the particle size distribution based on the volume of the metal hydroxide particles used as starting materials (D 50 The size can be greater than or equal to about 10 nm and less than or equal to about 10 μm, greater than or equal to about 0.1 μm and less than or equal to about 8 μm, or greater than or equal to about 0.5 μm and less than or equal to about 5 μm. This applies to metal oxide particles used as starting materials.

[0105] To prepare composite particles in which a larger amount of flame retardant-derived components are added to metal hydroxides, it is desirable to use metal hydroxide particles with the largest possible BET specific surface area as the starting material. It is also desirable to prepare a mixture by mixing the flame retardant component with metal hydroxide particles having a relatively large BET specific surface area, and to obtain the composite particles with a BET specific surface area within the aforementioned range by combining the mixture. When the amount of flame retardant added to the metal hydroxide particles increases, or when the reaction time for combining the metal hydroxide particles with the flame retardant component is prolonged, the BET specific surface area of ​​the composite particles tends to decrease. Therefore, since the BET specific surface area of ​​the composite particles can be controlled by changing these conditions, there is no particular limitation on the BET specific surface area of ​​the metal hydroxide particles used as the starting material; however, the BET specific surface area of ​​the metal hydroxide particles can, for example, be greater than or equal to about 100 m². 2 / g and less than or equal to approximately 500m 2 / g. Similarly, for metal oxide particles used as starting materials, the BET specific surface area can be greater than or equal to about 100 m². 2 / g and less than or equal to approximately 500m 2 / g.

[0106] 3-2. Manufacturing method of negative electrode First, a negative electrode slurry is prepared by dispersing a mixture of materials constituting the negative electrode mixture layer 22 in a solvent used for the negative electrode slurry. Then, the negative electrode mixture layer 22 is formed by coating the negative electrode slurry onto the negative electrode current collector 21 and drying the negative electrode slurry. Next, the negative electrode mixture layer 22 is pressed using a press to achieve a desired density. Thus, the negative electrode 2 is manufactured.

[0107] 3-3. Manufacturing method of non-aqueous electrolyte rechargeable battery Next, an electrode structure is fabricated by placing a separator 3 between the positive electrode 1 and the negative electrode 2. The electrode structure can then be processed into a desired shape (e.g., cylindrical, prismatic, laminated, button-shaped, etc.) and inserted into a container of the aforementioned shape. Subsequently, a non-aqueous electrolyte 4 is injected into the corresponding container to impregnate each pore in the separator or the gap between the positive electrode 1 and the negative electrode 2. Thus, a rechargeable lithium-ion battery is manufactured.

[0108] 4. Effects of the Example Implementation According to the non-aqueous electrolyte rechargeable battery 100 constructed as described above, because it includes a first particle containing boron nitride with a relatively low Young's modulus, and the aspect ratio (major axis / minor axis) of the first particle is set to be greater than or equal to about 3.0 and less than or equal to about 30, when punctured by a foreign object (such as a nail, for example), the intermediate layer 13 including the first particle can deform substantially along the surface shape of the positive electrode current collector, and can reduce or suppress the exposure of the positive electrode current collector.

[0109] Boron nitride can capture reactive oxygen species, thereby reducing or inhibiting electrolyte decomposition reactions, which in turn reduces or inhibits the potential temperature rise of the battery.

[0110] Because the intermediate layer 13 also includes a second particle containing metal hydroxide or metal oxide and flame retardant components, the temperature rise of the battery can be reduced or suppressed, and safety can be further significantly improved by reducing or suppressing the endothermic reaction caused by metal hydroxide or metal oxide and the decomposition reaction of the electrolyte caused by free radical capture by the flame retardant components.

[0111] 5. Another example embodiment This disclosure is not limited to the foregoing example embodiments.

[0112] For example, the second particle is not limited to the composite particles described above, and the following particles can be used.

[0113] 5-1. Second Embodiment Similar to the composite particles described in the example embodiments above, the composite particles described in the second embodiment are composite particles comprising at least one of metal hydroxide particles and metal oxide particles, as well as a flame retardant component, and their properties and composition are as follows.

[0114] When the composite particles are heated from about 80°C to about 1400°C, the amount of P2 gas desorbed from the composite particles, as measured by TDS-MS (referred to as MS1), can be greater than or equal to about 200 × 10⁻⁶. -6 mol / g and less than or equal to approximately 2500 × 10 -6 The amount of H2O gas desorbed from the composite particles (referred to as MS2), as measured by TDS-MS, when the composite particles are heated from about 80°C to about 1400°C, can be greater than or equal to about 50 × 10⁻⁶ mol / g, and when the composite particles are heated from about 80°C to about 1400°C. -6 mol / g and less than or equal to approximately 1000 × 10 -6 mol / g.

[0115] MS1 can be greater than or equal to approximately 300 × 10 -6 mol / g and less than or equal to approximately 2000 × 10⁻⁶ -6 mol / g, or greater than or equal to approximately 400 × 10⁻⁶-6 mol / g and less than or equal to approximately 1800 × 10 -6 mol / g.

[0116] MS2 can be greater than or equal to approximately 100 × 10 -6 mol / g and less than or equal to approximately 950 × 10 -6 mol / g, or greater than or equal to approximately 300 × 10⁻⁶ -6 mol / g and less than or equal to approximately 900 × 10 -6 mol / g.

[0117] Furthermore, the ratio of the amount of desorbed gas (MS1 / MS2) can be greater than or equal to about 0.1 and less than or equal to about 10.0, greater than or equal to about 0.3 and less than or equal to about 5.0, or greater than or equal to about 0.5 and less than or equal to about 3.0. By ensuring that the ratio of the amount of desorbed gas (MS1 / MS2) meets this desired range, a good balance can be struck between the reduction or suppression of temperature rise caused by modification of the flame retardant component and battery performance.

[0118] Furthermore, the BET specific surface area of ​​the composite particles, calculated via adsorption isotherms measured by adsorbing nitrogen onto the composite particles, can be greater than or equal to approximately 8 m². 2 / g and less than or equal to approximately 80m 2 / g, greater than or equal to approximately 10m 2 / g and less than or equal to approximately 75m 2 / g, or greater than or equal to approximately 15m 2 / g and less than or equal to approximately 75m 2 / g.

[0119] To prepare composite particles by adding a larger amount of flame retardant component to metal hydroxide, it is desirable to use metal hydroxide particles with the largest possible BET specific surface area as the starting material, and to mix the flame retardant component with metal hydroxide particles having a relatively large BET specific surface area, thereby achieving a composite particle BET specific surface area within the aforementioned range. When the amount of flame retardant added to the metal hydroxide particles increases, or when the reaction time for combining the metal hydroxide and flame retardant component is prolonged, the composite particle BET specific surface area tends to decrease. Therefore, since the BET specific surface area of ​​the composite particles can be controlled by changing these conditions, there is no particular limitation on the BET specific surface area of ​​the metal hydroxide particles used as the starting material; however, the specific surface area of ​​the metal hydroxide particles can, for example, be greater than or equal to about 100 m². 2 / g and less than or equal to approximately 500m 2 / g. The above description applies to metal oxide particles.

[0120] For the composite particles according to the example embodiment, the contents of Al (aluminum) and P (phosphorus) elements measured by inductively coupled plasma atomic emission spectrometry (ICP-AES) can be within the following ranges.

[0121] The content of Al in the composite particles can be greater than or equal to about 1% by mass and less than or equal to about 50% by mass, greater than or equal to about 3% by mass and less than or equal to about 40% by mass, or greater than or equal to about 5% by mass and less than or equal to about 30% by mass.

[0122] The content of phosphorus in the composite particles can be greater than or equal to about 1% by mass and less than or equal to about 50% by mass, greater than or equal to about 3% by mass and less than or equal to about 40% by mass, or greater than or equal to about 5% by mass and less than or equal to about 30% by mass.

[0123] To further enhance the endothermic effect of the composite particles, they can be modified with functional groups such as CH3- or CH2OH-. The degree of modification of functional groups, including those containing phosphorus (P) (e.g., phosphonic acids), can be evaluated by the desorption amounts of various gases derived from these functional groups, provided that the desorption amounts of each gas meet the following ranges. The desorption amounts of each gas can be adjusted by the type and amount of the metal hydroxides, metal oxides, and flame retardants used in the preparation of the composite particles.

[0124] When the composite particles are heated from about 80°C to about 1400°C, the amount of CH4 gas desorbed from the composite particles as measured by TDS-MS (referred to as MS3) can be 0 mol / g, but can be greater than 0 and less than or equal to about 1000 × 10⁻⁶. -6 mol / g, greater than or equal to approximately 10 × 10 -6 mol / g and less than or equal to approximately 700 × 10 -6 mol / g, or greater than or equal to approximately 30 × 10 - 6 mol / g and less than or equal to about 500 × 10 -6 The amount of desorbed CH3OH measured in the same manner (referred to as MS4) can be 0 mol / g, but can also be greater than 0 mol / g and less than or equal to approximately 4000 × 10⁻⁶ mol / g. -6 mol / g, greater than or equal to approximately 200 × 10 -6 mol / g and less than or equal to approximately 3000 × 10 -6 mol / g, or greater than or equal to approximately 500 × 10 -6 mol / g and less than or equal to approximately 3000 × 10 -6 mol / g.

[0125] When the composite particles are modified by functional groups including phenyl groups, the composite particles can be dispersed in the solvent when preparing a slurry for the intermediate layer using a non-aqueous solvent such as N-methyl-2-pyrrolidone (NMP).

[0126] Therefore, the amount of C6H6 desorbed from the composite particles at approximately 80°C to approximately 1400°C, as measured by TDS-MS (referred to as MS5), can be 0 mol / g, but it can also be greater than 0 mol / g and less than or equal to approximately 4000 × 10⁻⁶. -6 mol / g, greater than or equal to approximately 10 × 10 -6 mol / g and less than or equal to approximately 3000 × 10 -6 mol / g, or greater than or equal to approximately 100 × 10 -6 mol / g and less than or equal to approximately 3000 × 10 -6 mol / g.

[0127] Based on 100% by mass of total composite particles, the total amount of modified molecules (i.e., flame retardant components) in the composite particles can be in the range of greater than or equal to about 10% by mass and less than or equal to about 99% by mass, greater than or equal to about 20% by mass and less than or equal to about 97% by mass, or greater than or equal to about 30% by mass and less than or equal to about 95% by mass.

[0128] 5-2, Third Embodiment In addition, as composite particles, it is also possible to further use composite particles in which at least one of metal hydroxide particles and metal oxide particles is combined not only with the flame retardant component but also with conductive particles.

[0129] These composite particles can be described as follows.

[0130] Metal hydroxide particles and metal oxide particles can be any particles capable of inducing an endothermic reaction, and there are no particular limitations. Examples of metal hydroxides and metal oxides may include, for example, aluminum hydroxide, pseudoboehmite, boehmite, activated alumina, and kaolinite. These can be used alone, or two or more types of metal hydroxides and metal oxides can be used together.

[0131] The average primary particle size of metal hydroxide particles can be greater than or equal to about 10 nm and less than or equal to about 20 μm, or greater than or equal to about 50 nm and less than or equal to about 10 μm. The above description can be applied to metal oxide particles.

[0132] The conductive particles can be any type of conductive particle, and there are no particular limitations. Examples of materials constituting the aforementioned conductive particles may include, for example, carbon materials, metal nanoparticles, etc.

[0133] Examples of metal nanoparticles may include gold nanoparticles, silver nanoparticles, copper nanoparticles, etc.

[0134] Examples of carbon materials may include at least one of carbon black, natural graphite, artificial graphite, fibrous carbon, and sheet carbon.

[0135] Examples of carbon black may include furnace black, channel black, thermal black, Ketjen black, and acetylene black.

[0136] Examples of fibrous carbon can include carbon nanofibers such as single-layer carbon nanotubes, multilayer carbon nanotubes, etc., and examples of sheet-like carbon can include graphene, etc.

[0137] The composite particles may include the conductive particles described above, such that the 1350 cm⁻¹ measured by Raman spectroscopy... -1 Nearby peak area (A) D ) and 1580cm -1 Nearby peak area (A) G The ratio of (A) D / A G The value can be greater than or equal to about 0.5 and less than or equal to about 3.5, and is measured by Raman spectroscopy at 2680 cm⁻¹. -1 The half-peak full width (G'-FWHM) of the nearby peaks is greater than or equal to approximately 60 cm. -1 And less than or equal to approximately 150cm -1 Within the range.

[0138] The average primary particle size or fiber length of the conductive particles can be greater than or equal to about 1 nm and less than or equal to about 10 μm, or greater than or equal to about 10 nm and less than or equal to about 1 μm. When metal nanoparticles are used as conductive particles, metal nanoparticles with any particle size can be used, as long as the average primary particle size is on the order of nanometers (nm), but for example, the average primary particle size can be greater than or equal to about 1 nm and less than or equal to about 500 nm.

[0139] Based on the total composite particles, the amount of metal hydroxide particles and metal oxide particles in the composite particles can be greater than or equal to about 1% by mass and less than or equal to about 60% by mass, greater than or equal to about 5% by mass and less than or equal to about 50% by mass, or greater than or equal to about 10% by mass and less than or equal to about 40% by mass. When multiple types of metal hydroxide particles and metal oxide particles are used together, the amount refers to the total amount.

[0140] Based on the total composite particles, the amount of conductive particles in the composite particles can be greater than or equal to about 0.1% by mass and less than or equal to about 25% by mass, greater than or equal to about 0.5% by mass and less than or equal to about 20% by mass, or greater than or equal to about 1% by mass and less than or equal to about 15% by mass.

[0141] The composite particles have BET specific surface area and degree of modification of various modifying groups within the following ranges.

[0142] The specific surface area (BET1) calculated based on the adsorption isotherm measured by adsorbing water vapor into the composite particles can be greater than or equal to approximately 8 m². 2 / g and less than or equal to approximately 600m 2 / g, and the specific surface area (BET2) of the composite particles, calculated via an adsorption isotherm measured by adsorbing nitrogen into the composite particles, can be greater than or equal to approximately 8m². 2 / g and less than or equal to approximately 600m 2 / g.

[0143] BET1 can be greater than or equal to approximately 10m 2 / g and less than or equal to approximately 300m 2 / g, or greater than or equal to approximately 12m 2 / g and less than or equal to approximately 100m 2 / g.

[0144] BET2 can be greater than or equal to approximately 9m 2 / g and less than or equal to approximately 300m 2 / g, or greater than or equal to approximately 10m 2 / g and less than or equal to approximately 100m 2 / g.

[0145] In addition, the specific surface area ratio of these BET1 and BET2, BET1 / BET2, can be greater than or equal to about 0.2 and less than or equal to about 5.0, greater than or equal to about 0.5 and less than or equal to about 4.0, or greater than or equal to about 1.0 and less than or equal to about 3.0.

[0146] Furthermore, when the composite particles are heated from approximately 80°C to approximately 1400°C, the amount of P2 gas desorbed from the composite particles, as measured by TDS-MS (referred to as MS1), can be greater than or equal to approximately 300 × 10⁻⁶. -6 mol / g and less than or equal to approximately 3000 × 10 -6 mol / g. This amount of desorbed P2 (MS1) is an indicator of the degree of modification of the composite particles by phosphonic acid.

[0147] When the composite particles are heated from about 80°C to about 1400°C, the amount of H2O gas desorbed from the composite particles (referred to as MS2), as measured by TDS-MS, can be greater than or equal to about 30 × 10⁻⁶. -6 mol / g and less than or equal to approximately 1500 × 10 -6 mol / g. The amount of desorbed H2O constitutes a reference value for the degree of modification of the composite particles, and the ratio of the amounts of these desorbed gases, MS1 / MS2, can be greater than or equal to about 0.5 and less than or equal to about 5.0, greater than or equal to about 1.0 and less than or equal to about 4.0, or greater than or equal to about 1.5 and less than or equal to about 3.0.

[0148] To further enhance the endothermic effect of the composite particles, they can be modified with functional groups (such as CH3 groups and CH2OH groups). Similar to evaluating the degree of modification of phosphonic acids, the degree of modification of these functional groups can be evaluated by the desorption amounts of various gases derived from these functional groups, and the desorption amounts of various gases can meet the following ranges.

[0149] When the composite particles are heated from about 80°C to about 1400°C, it may be expected that the amount of CH4 desorbed from the composite particles (referred to as MS3), as measured by TDS-MS, can be greater than or equal to about 30 × 10⁻⁶. -6 mol / g and less than or equal to approximately 1000 × 10 - 6 The amount of desorbed CH3OH, measured in the same manner (referred to as MS4), can be greater than or equal to approximately 10 × 10 mol / g. - 6 mol / g and less than or equal to approximately 1000 × 10 -6 mol / g.

[0150] MS3 can be greater than or equal to approximately 50 × 10 -6 mol / g and less than or equal to approximately 300 × 10 -6 mol / g, or greater than or equal to approximately 60 × 10⁻⁶ -6 mol / g and less than or equal to approximately 250 × 10 -6 mol / g.

[0151] MS4 can be greater than or equal to approximately 20 × 10 -6 mol / g and less than or equal to approximately 2000 × 10⁻⁶ -6 mol / g, or greater than or equal to approximately 25 × 10⁻⁶ -6 mol / g and less than or equal to approximately 1900 × 10 -6 mol / g.

[0152] When composite particles are modified with functional groups including phenyl groups, they can be dispersed in a solvent when manufacturing slurries such as positive electrode composite slurries.

[0153] Therefore, the amount of C6H6 desorbed from the composite particles at approximately 80°C to approximately 1400°C, as measured by TDS-MS (referred to as MS5), can be greater than or equal to approximately 1 × 10⁻⁶. -6 mol / g and less than or equal to approximately 4000 × 10 -6 mol / g, greater than or equal to approximately 2 × 10 -6 mol / g and less than or equal to approximately 2000 × 10⁻⁶ -6 mol / g, or greater than or equal to approximately 3 × 10 -6 mol / g and less than or equal to approximately 1600 × 10 -6 mol / g.

[0154] Based on 100% by mass of total composite particles, the total amount of modified molecules in the composite particles can be in the range of greater than or equal to about 10% by mass and less than or equal to about 90% by mass, greater than or equal to about 20% by mass and less than or equal to about 80% by mass, or greater than or equal to about 30% by mass and less than or equal to about 70% by mass.

[0155] For the endothermic properties of composite particles achieved by the specific surface area and various modified groups as described above, the heat absorption at a temperature of about 50°C to about 250°C in differential scanning calorimetry can be greater than or equal to about 150 J / g and less than or equal to about 500 J / g, greater than or equal to about 170 J / g and less than or equal to about 400 J / g, or greater than or equal to about 180 J / g and less than or equal to about 300 J / g.

[0156] In this example embodiment, when the composite particles already include conductive particles, conductive agents other than the composite particles may or may not be added when forming the intermediate layer.

[0157] This disclosure is not limited to these exemplary embodiments, and various modifications can be made without departing from its scope.

[0158] Example The present disclosure is described in more detail below with reference to examples. However, the following examples are merely examples of the present disclosure, and the present disclosure is not limited to the following examples.

[0159] Preparation of composite particles used as the second particle: Examples 1 through 4, and comparative examples 2 and 3: Using 1.0g of kaolinite (Al2Si2O5(OH)4, D 50 : 1μm, BET: 120m 2As metal hydroxide particles, 5.0 g of phenyl phosphate was used as a flame retardant and dispersed in a mixed solution of 50 cc of ethanol and pure water (mixing ratio 1:1). After heating the dispersion at 70°C for 24 hours, it was filtered and washed with water and ethanol, and then the solid was vacuum dried on filter paper to obtain composite particles (A).

[0160] Examples 5 to 8: The composite particles (B) were obtained in the same manner as in Example 1, except that 1.0 g of activated alumina (D) was used. 50 1.5μm, BET: 312m 2 / g) as metal oxide particles, and 5.0g of methylphosphonic acid as flame retardant.

[0161] Examples 9 to 12: The composite particles (C) were obtained in the same manner as in Example 1, except that 1.0 g of pseudoboehmite (D) was used. 50 : 1.0μm, BET: 391m 2 / g) as metal hydroxide particles, and 5.0g of diphenyl phosphate as a flame retardant.

[0162] Examples 13 to 16: The composite particles (D) were obtained in the same manner as in Example 1, except that 1.0 g of aluminum hydroxide (D) was used. 50 : 1.2μm, BET: 212m 2 / g) as metal hydroxide particles, and 5.0g of phenylphosphonic acid as a flame retardant.

[0163] Manufacturing of intermediate layers Examples 1 through 16, and comparative examples 2 and 3: Using the first and second particles described in Table 1 below, the mass ratio of these first and second particles, carbon nanofibers as a conductive agent, and polyvinylidene fluoride as a binder for the intermediate layer was set to 64:16:2:18. These particles were then dispersed and mixed in N-methyl-2-pyrrolidone solvent to prepare the respective intermediate layer slurries. Next, the intermediate layer slurries were coated onto both surfaces of an aluminum current collector foil and dried, resulting in a coating weight (area density) of 0.5 mg / cm² on one surface. 2 To prepare the intermediate layer.

[0164] Compare examples 4 to 6: Intermediate layers of Comparative Examples 4 to 6 were prepared in the same manner as in Example 1, except that: active alumina, which was not treated with flame retardant components on the surface and inside, was added as metal oxide particles.

[0165] Manufacturing of positive electrode Examples 1 through 16 and comparative examples 2 through 8: By using LiCoO2 (D 50 A positive electrode mixture slurry was prepared by dispersing and mixing acetylene black and polyvinylidene fluoride (PVDF) in a mass ratio of 97.7:1.0:1.3 in N-methyl-2-pyrrolidone solvent. Next, the positive electrode mixture slurry was coated onto an intermediate layer and dried, resulting in a coating weight (area density) of 20.50 mg / cm² on one surface. 2 Then, a roller press is used to press the mixture to a density of 4.15 g / cc, thereby manufacturing the positive electrode.

[0166] Compare with Example 1: The positive electrode is manufactured in the same manner as in Example 1, except that the positive electrode mixture slurry is directly coated onto both surfaces of the aluminum current collector and dried without forming an intermediate layer.

[0167] Manufacturing of negative electrode Examples 1 to 16 and Comparative Examples 1 to 8: Artificial graphite, sodium carboxymethyl cellulose (CMC), and a styrene-butadiene aqueous dispersion were dissolved and dispersed in an aqueous solvent at a mass ratio of 97.5:1.0:1.5 (solvent-free dry powder, solid components) to prepare a negative electrode mixture slurry. Next, the negative electrode mixture slurry was coated onto both surfaces of a copper foil and dried, resulting in a coating weight (area density) of 15.0 mg / cm². 2 Then, the mixture is pressed using a roller press to achieve a negative electrode mixture layer density of 1.65 g / cc, in order to manufacture the negative electrode.

[0168] Manufacturing of rechargeable battery cells Examples 1 to 16 and Comparative Examples 1 to 8: Multiple positive and negative electrodes, each with a porous polypropylene separator, are stacked to achieve a battery design capacity of 300mAh, thus fabricating an electrode stack. When the positive and negative electrodes are placed inside the electrode stack, a mixture layer formed on both surfaces of the current collector is used; however, for the positive or negative electrode positioned on the outermost layer, a mixture layer formed on only one surface is used. For example, an electrode plate with an area of ​​8.5 cm² is fabricated. 2The positive electrode (two surfaces, 5 pieces) and electrode plate area are 10.0 cm². 2 The negative electrode consists of four pieces on two surfaces and two pieces on one surface. Subsequently, the electrode stack is housed in an aluminum laminate and the leads are pulled out to the outside by soldering nickel and aluminum leads to the negative and positive electrodes, respectively. Electrolyte is injected into the stack, and the aluminum laminate is sealed under reduced pressure to manufacture a rechargeable battery cell before initial charging. The electrolyte is prepared by dissolving 1.3 M LiPF6 and 1 wt% vinylene carbonate in a mixed solvent of ethylene carbonate / dimethyl carbonate / fluoroethylene carbonate at a volume ratio of 15 / 80 / 5.

[0169] Evaluation of the first particle, the second particle, or the metal oxide particle The evaluation of the first particle, second particle, or metal oxide particle (active alumina) used in the example and comparative examples is carried out as follows.

[0170] Particle size measurement: The particle size of the first and second particles or metal oxide particles is taken as 50% of the cumulative value of the particle size distribution based on particle size volume in the particle size distribution obtained by laser diffraction / scattering. 50 Evaluation was conducted. The particle size of the first and second particles or metal oxide particles was measured using the following measuring equipment and conditions.

[0171] Measurement device: MT3300 laser diffraction / scattering particle size distribution measurement device (manufactured by Micro Track Bell) Permeability: Permeable Shape: Non-spherical Cycle speed: 7 Measurement time: 30 seconds Number of repetitions: 3 Refractive index: a. First particle, second particle, or metal oxide particle: 1.65-0.00i b. Ethanol solvent: 1.36-0.00i The ratio of the major axis to the minor axis and the length-to-thickness ratio of the first particle: In the given examples and comparisons, the average particle size (D) obtained by the laser diffraction / scattering method as described above will be used. 50 ) is used as the long axis of the first particle.

[0172] After the first particle was attached to the carbon ribbon, the thickness of 100 random particles was measured using a scanning electron microscope JSM-7800F (manufactured by Nippon Electronics Co., Ltd.). The arithmetic mean was used as the minor axis of the first particle, and the above-mentioned major axis and minor axis ratio (major axis / minor axis, length-to-thickness ratio) was calculated.

[0173] The mass of the desorbed gas from the second particle: Thermal desorption gas mass spectrometry (TDS-MS) was performed using a TDS-1200 thermal desorption mass spectrometer manufactured by Electronic Science, and the desorption amounts of two phosphorus molecules and water molecules were measured and analyzed according to the following method.

[0174] In TDS, the second particle was placed using a sample stage made of quartz and a sample dish made of SiC. The heating rate was 60 °C / min. Temperature rise was controlled by monitoring the temperature on the sample surface. The sample weight was 1 mg (corrected for the actual weight (0.5 mg)). Detection was performed using a quadruple mass spectrometer with a voltage of 1000 V applied.

[0175] The amount (μmol / g) of each gas desorbed from the second particle (composite particle) during heating from 80°C to 1400°C was measured using TDS. The mass number [M / z] used for the analytical measurement was 18 for H2O and 62 for P2, where the gas corresponding to the mass number is each of the aforementioned substances. Here, the amount of H2O desorbed was obtained using the cumulative value from 80°C to 200°C over the entire temperature range.

[0176] Confirmation of the exothermic peak at 150°C or lower in the presence of electrolyte and second particles or metal oxide particles. 2.0 mg of various second particles (various composite particles) or metal oxide particles (active alumina) manufactured as described above and 0.5 mg of the same electrolyte used in the manufacture of rechargeable battery cells were placed in a special airtight container and sealed. The exothermic peak of the second particles or metal oxide particles was then measured under the following conditions to confirm the presence or absence of an exothermic peak at 150°C or lower. In Comparative Examples 4 to 6, a distinct exothermic peak was observed near 100°C, but this exothermic peak was not observed in Examples 1 to 4. Furthermore, the maximum exothermic peak temperature of each particle was measured using a differential scanning calorimeter (DSC) (manufactured by Hitachi High-Tech Sciences Co., Ltd.) at a heating rate of 5 K / min according to JIS K7121, confirming the peak of the exothermic decomposition temperature.

[0177] Evaluation of rechargeable battery cells Cyclic characteristics The rechargeable battery cells according to Examples 1 to 16 and Comparative Examples 1 to 8 were charged to 4.4V at a constant current of 0.1CA (design capacity in ampere-hours) in a 25°C thermostat, and then charged to 0.05CA at a constant voltage of 4.4V. Subsequently, the battery cells were discharged to 3.0V at a constant current of 0.1CA. Furthermore, in a 25°C thermostat, under conditions of a charging cutoff voltage of 4.4V and a discharging cutoff voltage of 3.0V, the initial discharge capacity of the battery cells after the first cycle was measured by charging at a constant current of 0.2CA, charging at a constant voltage of 0.05CA, and discharging at a constant current of 0.2CA. The cycle life of a rechargeable battery cell was tested by subjecting it to 100 charge-discharge cycles at 45°C, a charge cutoff voltage of 4.3V, and a discharge cutoff voltage of 3.0V, through constant charging at 0.5CA, constant voltage charging at 0.05CA, and constant discharging at 0.5CA. After 100 cycles, the discharge capacity of the battery cell was measured at constant charging at 0.2CA, constant voltage charging at 0.05CA, and constant discharging at 0.2CA, and divided by the initial discharge capacity to obtain the capacity retention rate after 100 cycles.

[0178] Nail puncture test A nail puncture test was performed at a speed of 1 mm / s by penetrating the central portion of 10 rechargeable battery cells manufactured in Examples 1 to 16 and Comparative Examples 1 to 8 with nails of 3 mm in diameter. An "abnormality" was defined as the external temperature of the battery cell reaching 50°C or higher 5 seconds after nail penetration, and the abnormality rate was evaluated by 10 battery tests.

[0179] Heating test Ten rechargeable battery cells (each) manufactured in Examples 1 to 16 and Comparative Examples 1 to 8 were charged to 4.45V at a constant current of 0.1CA at their design capacity in a 25°C thermostat, and then charged at a constant voltage until the voltage dropped to 0.05CA at 4.45V. Subsequently, the battery cells were discharged to 3.0V at a constant current of 0.1CA. Alternatively, after one cycle of constant current charging at 0.2CA, constant voltage charging at 0.05CA, and constant current discharging at 0.2CA in a 25°C thermostat with a charging cutoff voltage of 4.45V and a discharging cutoff voltage of 3.0V, the battery cells were again charged to 4.45V at constant current / constant voltage, and these were considered the initial battery cells. These rechargeable battery cells were placed in a thermostat heated to 165°C for 1 hour, and any instance where the voltage of a battery cell dropped to 4.2V or lower was considered an “abnormal occurrence.” The abnormal occurrence rate was evaluated using 10 battery cell tests.

[0180] Evaluation results The types, properties, and amounts of the first particle, the second particle, and the metal oxide particles used instead of the second particle in the above examples and comparative examples are shown in Table 1 below.

[0181] In addition, the evaluation results of Examples 1 to 16 and Comparative Examples 1 to 8 are summarized and shown in Table 2 below.

[0182] Table 1:

[0183]

[0184] Table 2:

[0185] consider: As can be seen from the results in Table 2 above, the anomaly rate in the nail penetration test was sufficiently reduced or suppressed in Examples 1 to 16. This is likely because, in Examples 1 to 16, by using an insulating material including boron nitride as the first particle, setting the ratio of the long axis to the short axis (long axis / short axis) of the first particle to be greater than or equal to about 3.0 and less than or equal to about 30, and using a material including at least one of metal hydroxide and metal oxide and a flame retardant component as the second particle, the temperature rise inside the battery was sufficiently reduced or suppressed even under conditions where a battery short circuit might occur. On the other hand, in Comparative Examples 1 to 8 (Comparative Example 1 excluding the intermediate layer, Comparative Examples 2 and 3 where the length-to-thickness ratio of the first particle included in the intermediate layer is outside the above range, Comparative Examples 4 to 6 using metal oxide particles (because they replace the second particle), and Comparative Examples 7 and 8 excluding the second particle), the anomaly rate was significantly higher than in Examples 1 to 16.

[0186] Factors contributing to the effectiveness of Examples 1 through 16 may include the fact that, upon nail penetration, the intermediate layer comprising the first particle with a low Young's modulus and an adjusted aspect ratio deforms to conform to the shape of the nail or positive electrode current collector, thereby reducing the exposure rate of the positive electrode current collector. Furthermore, because the first particle, comprising boron nitride with active oxygen-trapping properties, and the second particle, comprising at least one of metal hydroxide and metal oxide, and a flame retardant component, are present near the positive electrode current collector, heat generation at the short-circuit point can be reduced even in the event of a micro-short circuit.

[0187] On the other hand, as in Comparative Example 2, when the first particle with an excessively high aspect ratio is included in the intermediate layer, the number of the first particles present in the intermediate layer has been reduced or the first particles break rather than deform during penetration, which may result in insufficient reduction of the exposure rate of the positive electrode current collector.

[0188] It can be confirmed that all composite particles used as the second particle in Examples 1 to 16 exhibit high efficiency. The properties of these composite particles are not limited to the range confirmed in Examples 1 to 16; for example, MS1 is greater than or equal to 200 × 10⁻⁶. -6 mol / g and less than or equal to 2500 × 10 -6 mol / g, MS2 greater than or equal to 50 × 10 -6 mol / g and less than or equal to 1000 × 10 -6 The ratio of the amount of desorbed gas MS1 / MS2 is greater than or equal to 0.5 and less than or equal to 10, and the same effect can be exhibited within the range described in each of the above example embodiments.

[0189] In addition, according to Examples 1 to 16, not only can internal short circuits that occur when the battery is punctured be reduced or suppressed, and the increase in the internal temperature of the battery be sufficiently reduced or suppressed, but the degradation of battery performance (such as cycle characteristics) can also be reduced or suppressed.

[0190] It will be apparent to those skilled in the art to which this disclosure pertains that various changes or modifications can be made within the scope of the technical concept described in the claims, and it is understood that such changes are within the technical scope of this disclosure.

[0191] Explanation of reference numerals in the attached figures 100… Non-aqueous electrolyte rechargeable battery 1…Positive electrode 11…Positive electrode current collector 12…Positive electrode mixture layer 13…Intermediate layer 2…Negative electrode 21…Negative electrode current collector 22…Negative electrode mixture layer 3…diaphragm 4…Non-aqueous electrolytes 5… Container.

Claims

1. A positive electrode for a non-aqueous electrolyte rechargeable battery, the positive electrode comprising: Positive electrode current collector; Positive electrode mixture layer; as well as The intermediate layer is located between the positive electrode current collector and the positive electrode mixture layer. The intermediate layer comprises a first particle and a second particle. The first particle comprises boron nitride and has insulating properties. The second particle comprises at least one of a metal hydroxide and a metal oxide, as well as a flame retardant component. The ratio of the major axis to the minor axis of the first particle is greater than or equal to 3.0 and less than or equal to 30. The 50% cumulative value of the particle size distribution based on the volume of the first particle is greater than or equal to 0.01 μm and less than or equal to 8 μm, and The 50% cumulative value of the particle size distribution based on the volume of the second particle is greater than or equal to 0.01 μm and less than or equal to 8 μm.

2. The positive electrode according to claim 1, wherein: The amount of P2 desorbed from the second particle at temperatures between 80°C and 1400°C, MS1, is greater than or equal to 200 × 10⁻⁶. -6 mol / g and less than or equal to 2500 × 10 -6 mol / g The amount of H2O desorbed from the second particle at temperatures between 80°C and 200°C, MS2, is greater than or equal to 50 × 10⁻⁶. -6 mol / g and less than or equal to 1000 × 10 -6 mol / g, and The ratio of the amount of desorbed P2 to the amount of desorbed H2O, MS1 / MS2, satisfies equation (1): 0.5≤(MS1 / MS2)≤10 (1).

3. The positive electrode according to claim 1, wherein, In the second particle, the surface or interior of at least one of the metal hydroxide and the metal oxide is modified with a flame retardant.

4. The positive electrode according to claim 1, wherein, The metal hydroxide includes at least one of kaolinite, pseudoboehmite, boehmite, and aluminum hydroxide.

5. The positive electrode according to claim 1, wherein, The metal oxide includes active alumina.

6. The positive electrode according to claim 3, wherein, The flame retardant includes at least one of phosphoric acid, phosphate ester, phosphonic acid, phosphonate, hypophosphonic acid, and hypophosphonate.

7. The positive electrode according to claim 1, wherein, The thickness of the intermediate layer is greater than or equal to 0.1 μm and less than or equal to 10 μm.

8. The positive electrode according to claim 1, wherein, The intermediate layer also includes a conductive agent.

9. The positive electrode according to claim 8, wherein, The conductive agent includes at least one of carbon nanofibers and carbon black.

10. A non-aqueous electrolyte rechargeable battery, said non-aqueous electrolyte rechargeable battery comprising: Positive electrode, negative electrode, Diaphragm, and Non-aqueous electrolyte, The positive electrode is a positive electrode used in a non-aqueous electrolyte rechargeable battery according to any one of claims 1 to 9.

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