Electrode active material composite particles, electrode mixture, and battery

Abstract

This invention relates to electrode active material composite particles, electrode hybrid materials, and batteries. The electrode active material composite particles according to this disclosure comprise a porous carbon material and silicon retained within the porous carbon material. When measured by gas adsorption, the electrode active material composite particles according to this disclosure have pores of 10 nm or less in an amount of 0.22 cc / g or more. The electrode hybrid material according to this disclosure comprises the electrode active material composite particles according to this disclosure. The battery according to this disclosure has an electrode active material layer, and the electrode active material layer comprises the electrode hybrid material according to this disclosure.

Description

Technical Field

[0001] This disclosure relates to electrode active material composite particles, electrode hybrid materials, and batteries. Background Technology

[0002] Japanese Patent Application Publication No. 2024-073597 (JP 2024-073597 A) discloses a composite comprising a porous carbon framework and silicon, and an electrode comprising such a composite. JP 2024-073597 A discloses a method for embedding silicon into a porous carbon framework using silane gas via chemical vapor deposition (CVD). Summary of the Invention

[0003] Silicon electrode active materials can expand and contract during battery charging and discharging. Therefore, volume changes can occur in batteries containing silicon electrode active materials due to this expansion and contraction. Even with composite materials containing porous carbon materials and silicon as electrode active materials, there is room for improvement in suppressing this volume change in the battery.

[0004] The purpose of this disclosure is to provide electrode active material composite particles capable of suppressing volume changes in a battery, an electrode mixture containing such electrode active material composite particles, and a battery containing such an electrode mixture.

[0005] The inventors have discovered that the above problems can be solved by the following means.

[0006] First aspect

[0007] An electrode active material composite particle, comprising

[0008] Porous carbon materials; and

[0009] Silicon retained within the porous carbon material, wherein

[0010] When measured by gas adsorption, the electrode active material composite particles contain pores of less than 10 nm in an amount of more than 0.22 cc / g.

[0011] Second aspect

[0012] According to the electrode active material composite particles of the first aspect, wherein, when measured by gas adsorption method, the electrode active material composite particles contain pores of less than 2 nm in an amount of more than 0.15 cc / g.

[0013] Third aspect

[0014] According to the electrode active material composite particles described in the first or second aspect, wherein

[0015] When measured by gas adsorption, the electrode active material composite particles contain

[0016] The amount of the pores smaller than 10 nm in the range of 0.50 cc / g or more and 0.60 cc / g or less, and

[0017] The pore size of 2 nm or less is 0.25 cc / g or more and 0.35 cc / g or less.

[0018] Fourth aspect

[0019] An electrode hybrid material comprising electrode active material composite particles according to any one of the first to third aspects.

[0020] Fifth aspect

[0021] A battery comprising an electrode active material layer, wherein the electrode active material layer comprises an electrode hybrid material according to the fourth aspect.

[0022] According to this disclosure, it is possible to provide electrode active material composite particles capable of suppressing volume changes in a battery, an electrode mixture containing such electrode active material composite particles, and a battery containing such an electrode mixture. Attached Figure Description

[0023] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention are described below with reference to the accompanying drawings, wherein like symbols denote like elements, and wherein: Figure 1 It is a graph showing the cumulative pore size distribution of the embodiments, comparative examples, and porous carbon materials; and Figure 2 This is a graph showing the micropore size distribution of the embodiments, comparative examples, and porous carbon materials. Detailed Implementation

[0024] The embodiments of this disclosure are described in detail below. Note that this disclosure is not limited to the following embodiments, and various modifications can be made within the scope of this disclosure.

[0025] Electrode active material composite particles

[0026] The electrode active material composite particles according to this disclosure comprise porous carbon material and silicon contained within the porous carbon material. When measured by gas adsorption, the electrode active material composite particles according to this disclosure have pores of 10 nm or less in an amount of 0.22 cc / g or more.

[0027] The inventors have discovered that when the electrode active material composite particles containing porous carbon material and silicon contained within the porous carbon material have a predetermined number or more of pores with relatively small pore sizes, it is possible to suppress battery volume changes that accompany the expansion and contraction of silicon during battery charging and discharging.

[0028] The reason for this is speculated as follows, without intending to be bound by any theory. For example, when manufacturing batteries, especially solid-state batteries, the electrode active material layer is sometimes pressed. It is believed that pores with relatively small diameters are not easily crushed by pressing. The electrode active material composite particles according to this disclosure have a predetermined number or more of these pores, which is believed to mitigate the aforementioned effects of expansion and contraction, and thus suppress volume changes in the battery.

[0029] "Electrode active material" can be "positive electrode active material" or "negative electrode active material", and can be particularly "negative electrode active material".

[0030] The elements constituting the electrode active material composite particles according to this disclosure will be described below.

[0031] Porous carbon materials

[0032] The electrode active material composite particles according to this disclosure comprise a porous carbon material. The porous carbon material retains silicon within its pores.

[0033] Porous carbon materials are not particularly limited. Porous carbon materials can be, for example, activated carbon. Porous carbon materials can be materials having interconnected pores in which the pores are connected to each other. An example of such a material is the commercially available product CNovel (registered trademark) MH-00.

[0034] The pore size and pore volume of porous carbon materials are not particularly limited. When measured by gas adsorption, porous carbon materials can have pores smaller than 10 nm in amounts of 0.30 cc / g or more, 0.40 cc / g or more, 0.50 cc / g or more, 0.55 cc / g or more, or 0.60 cc / g or more, and can also have pores smaller than 10 nm in amounts of 1.00 cc / g or less, 0.90 cc / g or less, 0.80 cc / g or less, 0.75 cc / g or less, or 0.70 cc / g or less.

[0035] The maximum value of the peak in the micropore size distribution of porous carbon materials, as determined by gas adsorption, can be above 1 nm, above 2 nm, above 3 nm, or above 4 nm, and can be below 10 nm, below 7 nm, below 5 nm, or below 4 nm.

[0036] Gas adsorption methods are not particularly limited. For example, after determining the N2 adsorption isotherm, the cumulative pore size distribution and differential pore size distribution can be obtained using the BJH (Barrett-Joyner-Halenda) method. In this case, the BELSORP MAX X specific surface area and pore size distribution measuring device manufactured by Microtrac can be used. The pore size and pore volume can be determined from the cumulative and differential pore size distributions obtained thereby. The pore size and pore volume of the electrode active material composite particles described below can also be determined in a similar manner.

[0037] silicon

[0038] The electrode active material composite particles according to this disclosure contain silicon contained within a porous carbon material. The silicon functions as the electrode active material, thereby expanding and contracting during the charging and discharging of the battery.

[0039] Silicon is not particularly restricted and can be silicon manufactured, for example, using alkoxysilanes as raw materials by the methods described below.

[0040] The shape and size of silicon are not particularly restricted, as long as silicon functions as an electrode active material.

[0041] In the electrode active material composite particles according to this disclosure, the mass ratio of silicon to porous carbon material can be 0.1 or more and 10.0 or less. This mass ratio can be 0.1 or more, 0.3 or more, 0.5 or more, 0.7 or more, 0.9 or more, or 1.0 or more, and can be 10.0 or less, 7.0 or less, 5.0 or less, 3.0 or less, 2.0 or less, or 1.0 or less. That is, the mass ratio of silicon to porous carbon material can be 1:1. By setting the mass ratio of silicon to porous carbon material within the above range, the relationship between the pore size and pore volume of the electrode active material composite particles according to this disclosure can be easily set within the range of this disclosure.

[0042] hole

[0043] When measured by gas adsorption, the electrode active material composite particles according to this disclosure have pores of less than 10 nm in amount of 0.22 cc / g or more. This can mitigate the effects of silicon expansion and contraction during battery charging and discharging, thereby suppressing battery volume changes.

[0044] When measured by gas adsorption, the composite particles of the electrode active material can have pores smaller than 10 nm in amounts of 0.25 cc / g or more, 0.30 cc / g or more, 0.35 cc / g or more, 0.40 cc / g or more, 0.45 cc / g or more, or 0.50 cc / g or more, and can also have pores smaller than 10 nm in amounts of 1.00 cc / g or less, 0.90 cc / g or less, 0.80 cc / g or less, 0.75 cc / g or less, 0.70 cc / g or less, 0.65 cc / g or less, 0.60 cc / g or less, or 0.55 cc / g. This can effectively suppress the volume change of the battery.

[0045] When measured by gas adsorption, the electrode active material composite particles according to this disclosure can have pores of 2 nm or less with an amount of 0.15 cc / g or more, 0.20 cc / g or more, or 0.25 cc / g or more, and can also have pores of 2 nm or less with an amount of 0.45 cc / g or less, 0.40 cc / g or less, or 0.35 cc / g or less. This can effectively suppress the volume change of the battery.

[0046] The electrode active material composite particles according to this disclosure can have pores of 10 nm or less in amounts of 0.40 cc / g or more and 0.70 cc / g or less, 0.45 cc / g or more and 0.65 cc / g or less, or 0.50 cc / g or more and 0.60 cc / g, and can also have pores of 2 nm or less in amounts of 0.15 cc / g or more and 0.45 cc / g or less, 0.20 cc / g or more and 0.40 cc / g or less, or 0.25 cc / g or more and 0.35 cc / g. This can effectively suppress the volume change of the battery.

[0047] Regarding this disclosure, "vias below 10nm" and "vias below 2nm" include the following: • Pores in the porous carbon material that are completely unfilled with silicon and / or insufficiently filled with silicon, thus leaving pores • The voids formed between silicon and porous carbon material in the pores of silicon-filled porous carbon material, and Pores in porous silicon.

[0048] The aforementioned “voids” and “pores in porous silicon” will be described in detail later, but these can be achieved by removing magnesium oxide that may be generated during the fabrication of composite particles of electrode active materials.

[0049] Method for manufacturing composite particles of electrode active materials

[0050] The electrode active material composite particles according to this disclosure can be prepared by a method comprising the following steps: (a) A composite containing silicon oxide within the porous carbon material; (b) Reducing the silicon oxide in the composite with magnesium to obtain an electrode active material composite particle precursor comprising silicon and magnesium oxide within the porous carbon material; and (c) Remove at least a portion of magnesium oxide from the electrode active material composite particle precursor.

[0051] Provide complex

[0052] The method may include (a) providing a composite containing silicon oxide within a porous carbon material. For the purposes of this disclosure, "silicon oxide" may be silicon dioxide (SiO2).

[0053] Methods for providing composites containing silicon oxide (SiO2) in porous carbon materials are not particularly limited, and examples include chemical vapor deposition (CVD). Specifically, for example, the following method is illustrated: First, the porous carbon material is placed in a furnace tube of a CVD apparatus, and the interior of the furnace tube is depressurized and then heated. Next, an oxygen line is inserted into a container containing alkoxysilanes, and the alkoxysilanes are bubbled with oxygen, thereby introducing oxygen containing alkoxysilane vapors into the furnace tube. A composite containing SiO2 within the porous carbon material can be provided by maintaining this state.

[0054] Alkoxysilanes are not particularly limited and can be, for example, tetraalkoxysilanes or alkoxysilanes modified with substituents other than alkoxy groups.

[0055] Tetraalkoxysilanes are not particularly limited and can be, for example, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane or combinations thereof, and in particular, tetraethoxysilane (TEOS).

[0056] The alkoxysilane modified with substituents other than alkoxy groups is not particularly limited. The substituents other than alkoxy groups are not particularly limited and can be, for example, methyl, ethyl, phenyl, vinyl, etc. The alkoxy group is not particularly limited and can be, for example, methoxy, ethoxy, etc. The number of substituents other than alkoxy groups and the number of alkoxy groups are not particularly limited.

[0057] The heating temperature is not particularly limited and can be, for example, above 100°C, above 300°C, above 400°C, or above 500°C, and can also be below 1000°C, below 800°C, below 600°C, or below 500°C.

[0058] The holding time in which oxygen containing alkoxysilane vapor is introduced into the furnace tube is not particularly limited, and can be, for example, more than 1 hour, more than 3 hours, more than 5 hours, or more than 6 hours, or can be less than 30 hours, less than 20 hours, less than 15 hours, less than 10 hours, less than 8 hours, or less than 6 hours.

[0059] Reduction of silicon oxide

[0060] The above method may include (b) using magnesium (Mg) to reduce silicon oxide (SiO2) in the composite to obtain an electrode active material composite particle precursor containing silicon (Si) and magnesium oxide (MgO) within a porous carbon material.

[0061] The method of reducing SiO2 with Mg is not particularly limited, and examples include methods in which Mg vapor is contacted with the complex. The method of generating Mg vapor is not particularly limited, and examples include methods of heating a reducing agent, such as Mg alloys or metallic Mg, as a Mg source.

[0062] Mg alloys are not particularly limited and can be at least one type selected from, for example, Mg2Si, MgCa, MgCu2, MgNi2 and MgSn.

[0063] There are no particular restrictions on the pressure used when reducing SiO2 with Mg. This pressure can be, for example, less than 1 atmosphere, less than 100 Pa, or less than 20 Pa. This pressure can be, for example, the Mg vapor pressure below the equilibrium pressure of the reversible decomposition reaction in which Mg2Si decomposes into Mg vapor and Si.

[0064] The temperature during the reduction of SiO2 using Mg is not particularly limited, and can be, for example, above 500°C, above 600°C, or above 650°C, and can be below 900°C, below 800°C, below 700°C, or below 650°C. Therefore, it is possible to increase the volume of pores with a diameter of 20 nm or less in the porous silicon obtained after the following step (c).

[0065] There is no particular limitation on the time for reducing SiO2 with Mg, and it can be, for example, more than 1 hour, more than 3 hours, more than 5 hours, or more than 10 hours, and it can also be less than 30 hours, less than 20 hours, less than 15 hours, or less than 10 hours.

[0066] The amount of Mg source can be the amount of Mg vapor that produces more than 1 molar equivalent relative to the number of moles of SiO2, that is, the amount that can appropriately reduce SiO2.

[0067] The mass ratio of the Mg source to the complex is not particularly limited, as long as it can adequately reduce SiO2. This mass ratio can be, for example, 1 or more, 2 or more, or 2.5 or more, and can be 10 or less, 5 or less, or 2.5 or less.

[0068] Specific examples of the method in step (b) include the following: First, the complex and the Mg source are placed in a reaction vessel. Next, the reaction vessel is placed in a vacuum furnace, and the interior of the vacuum furnace is evacuated by a rotary pump while the temperature is increased to heat the reaction vessel.

[0069] Removal of magnesium oxide

[0070] The above method may include (c) removing at least a portion of MgO from the electrode active material composite particle precursor. As a result, electrode active material composite particles are generated. Furthermore, by removing MgO, voids are formed between Si and the porous carbon material in the pores filled with Si, and the silicon in the electrode active material composite particles is also porousized, thereby generating porous silicon.

[0071] The method for removing at least a portion of MgO is not particularly limited, and examples include methods in which an electrode active material composite particle precursor is treated with acid.

[0072] The method of treating electrode active material composite particle precursors with acid is not particularly limited, and an example of such a method is to mix the electrode active material composite particle precursors with acid.

[0073] The acid is not particularly restricted, and examples include inorganic acids such as hydrochloric acid, nitric acid, and sulfuric acid.

[0074] The concentration of acid is not particularly limited and can be set appropriately according to the type of acid.

[0075] When using acid to remove MgO, the above method can be further included by washing the electrode active material composite particles with water, alcohol, etc., and by drying.

[0076] Electrode hybrid materials

[0077] The electrode hybrid material according to this disclosure comprises composite particles of electrode active materials according to this disclosure. The electrode hybrid material may optionally include a solid electrolyte, conductive additives, binders, etc.

[0078] In this disclosure, the term "electrode composite material" refers to a composition that can be used alone or in combination with other components to form an electrode active material layer. Furthermore, in this disclosure, the term "electrode composite material slurry" refers to a slurry that includes an "electrode composite material" and also contains a dispersion medium, and can be applied and dried to form an electrode active material layer.

[0079] In the context of this disclosure, "electrode hybrid material" can be "positive electrode hybrid material" or "negative electrode hybrid material", and can be particularly "negative electrode hybrid material".

[0080] The elements constituting the electrode hybrid material according to this disclosure will be described below.

[0081] Electrode active material composite particles

[0082] The above description can be used as a reference for information on composite particles of electrode active materials.

[0083] The content of electrode active material composite particles in the electrode hybrid material is not particularly limited and can be appropriately set considering factors such as the desired capacity of the battery.

[0084] solid electrolyte

[0085] Examples of solid electrolytes include inorganic solid electrolytes, such as sulfide solid electrolytes, oxide solid electrolytes, nitride solid electrolytes, and halide solid electrolytes, and organic polymer electrolytes, such as polymer electrolytes. Solid electrolytes can be particularly sulfide solid electrolytes.

[0086] For example, when the battery is a lithium-ion rechargeable battery, the solid electrolyte can have lithium-ion conductivity.

[0087] Examples of lithium-ion conductive sulfide solid electrolytes include solid electrolytes containing Li, X (where X is at least one of P, As, Sb, Si, Ge, Sn, B, Al, Ga, and In), and S. Furthermore, sulfide solid electrolytes may also contain at least one of O and halogens. Examples of halogens include F, Cl, Br, and I.

[0088] Examples of sulfide solid electrolytes include Li₂S-P₂S₅, Li₂S-P₂S₅-LiI, Li₂S-P₂S₅-GeS₂, Li₂S-P₂S₅-Li₂O, Li₂S-P₂S₅-Li₂O-LiI, Li₂S-P₂S₅-LiBr, Li₂S-SiS₂, Li₂S-SiS₂-LiI, Li₂S-SiS₂-LiBr, Li₂S-SiS₂-LiCl, Li₂S-SiS₂-B₂S₃-LiI, Li₂S-SiS₂-P₂S₅-LiI, Li₂S-B₂S₃, and Li₂S-P₂S₅-Z. m S n (where m and n are positive numbers, and Z is any one of Ge, Zn, and Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Lix MO y (where x and y are positive numbers, and M is any one of P, Si, Ge, B, Al, Ga, and In).

[0089] Examples of oxide solid electrolytes with lithium-ion conductivity include solid electrolytes containing Li, Y (where Y is at least one of Nb, B, Al, Si, P, Ti, Zr, Mo, W, and S), and O. Specific examples of oxide solid electrolytes include garnet solid electrolytes, such as Li7La3Zr2O. 12 Li 7–x La3(Zr 2–x Nb x )O 12 (0≤x≤2), Li5La3Nb2O 12 Such as; perovskite solid electrolytes, such as (Li,La)TiO3, (Li,La)NbO3, (Li,Sr)(Ta,Zr)O3, etc.; NASICON solid electrolytes Li(Al,Ti)(PO4)3 and Li(Al,Ga)(PO4)3; Li-PO solid electrolytes, such as Li3PO4, LIPON (a compound in which part of the O in Li3PO4 is replaced by N), etc.; and Li-BO solid electrolytes, such as Li3BO3, a compound in which part of the O in Li3BO3 is replaced by C, etc.

[0090] The content of solid electrolyte in the electrode hybrid material is not particularly limited and can be appropriately set considering desired ionic conductivity, etc.

[0091] Conductive additives

[0092] The conductive additive can be, for example, carbon materials, metal particles, or combinations thereof. Carbon materials can be, for example, non-fibrous carbon materials, such as acetylene black (AB), Ketjen black (KB), etc.; fibrous carbon materials, such as vapor-grown carbon fibers (VGCF), carbon nanotubes (CNT), and carbon nanofibers (CNF), or combinations thereof. Metal particles can be, for example, nickel, copper, iron, stainless steel, etc., or combinations thereof.

[0093] The content of conductive additives in the electrode hybrid material is not particularly limited and can be appropriately set considering the required conductivity, etc.

[0094] adhesives

[0095] The adhesive may be, for example, a rubber-based adhesive, such as butadiene rubber, hydrogenated butadiene rubber, styrene-butadiene rubber (SBR), hydrogenated styrene-butadiene rubber, nitrile rubber, hydrogenated nitrile rubber, acrylate butadiene rubber (ABR), ethylene propylene rubber, etc.; a fluoride-based adhesive, such as polyvinylidene fluoride (PVDF), polyvinylidene fluoride-polyhexafluoropropylene copolymer (PVDF-HFP), polytetrafluoroethylene, fluororubber, etc.; a polyolefin-based thermoplastic resin, such as polyethylene, polypropylene, polystyrene, etc.; an imide-based resin, such as polyimide, polyamide-imide, etc.; an amide-based resin, such as polyamide, etc.; an acrylic resin, such as polymethyl acrylate, polyethyl acrylate, etc.; a methacrylic resin, such as polymethyl methacrylate, polyethyl methacrylate, etc.; or a combination thereof.

[0096] The amount of binder in the electrode mixture is not particularly limited and can be appropriately set considering desired bonding properties, etc.

[0097] Other ingredients

[0098] Electrode hybrid materials may or may not contain other components besides those mentioned above.

[0099] Battery

[0100] The battery according to this disclosure has an electrode active material layer, and the electrode active material layer comprises an electrode hybrid material according to this disclosure. The battery according to this disclosure may sequentially comprise a negative electrode current collector layer, a negative electrode active material layer, an electrolyte layer, a positive electrode active material layer, and a positive electrode current collector layer. In this case, the electrode active material layer comprising the electrode hybrid material according to this disclosure may be a negative electrode active material layer or a positive electrode active material layer, and particularly may be a negative electrode active material layer.

[0101] The battery according to this disclosure can be a liquid battery or a solid-state battery, and particularly a solid-state battery. It should be noted that, in the context of this disclosure, a "solid-state battery" means a battery that contains at least a solid electrolyte as an electrolyte; therefore, a solid-state battery can be a combination of a solid electrolyte and a liquid electrolyte. Furthermore, a solid-state battery can also be an all-solid-state battery, i.e., a battery that contains only a solid electrolyte as an electrolyte.

[0102] The battery according to this disclosure can be a primary battery or a secondary battery, and in particular, it can be a lithium-ion secondary battery.

[0103] According to this disclosure, the battery can be constrained from both sides of the stacking direction of the aforementioned layers using constraint members such as end plates. Examples of constraint methods include, but are not limited to, methods using the constraint torque of bolts.

[0104] The elements constituting a battery according to this disclosure are described below. Note that the following description provides an example of an electrode active material layer containing an electrode hybrid material according to this disclosure that is a negative electrode active material layer.

[0105] Negative current collector layer

[0106] The negative electrode current collector layer can be in the form of foil, plate, mesh, stamped metal, foam, etc. The negative electrode current collector layer can be metal foil or metal mesh, or it can be carbon sheet, and especially metal foil. The negative electrode current collector layer can be made of multiple foils, sheets, etc.

[0107] The metal constituting the negative electrode current collector layer is not particularly limited and can be, for example, copper, nickel, chromium, gold, platinum, silver, aluminum, iron, titanium, zinc, cobalt, stainless steel, etc. In particular, the negative electrode current collector layer may contain at least one type of metal selected from copper, nickel, and stainless steel.

[0108] For purposes such as adjusting resistance, a coating may be formed on the surface of the negative electrode current collector layer. Furthermore, the negative electrode current collector layer can be formed by plating or vapor-depositing any of the aforementioned metals onto a metal foil or substrate. Additionally, when made of multiple metal foils, the negative electrode current collector layer may also include a layer interposed between these metal foils.

[0109] The thickness of the negative electrode current collector layer is not particularly limited, and can be, for example, 0.1 μm or more, or 1 μm or more, or less than 1 mm, or less than 100 μm.

[0110] Negative electrode active material layer

[0111] The negative electrode active material layer comprises an electrode hybrid material according to the present disclosure. Reference can be made to the above description regarding the electrode hybrid material according to the present disclosure. The negative electrode active material layer can be formed by molding the electrode hybrid material according to the present disclosure itself into a layer.

[0112] The thickness of the negative electrode active material layer is not particularly limited, and can be, for example, greater than 0.1 μm and less than 1000 μm.

[0113] solid electrolyte layer

[0114] The solid electrolyte layer contains at least solid electrolyte particles and may optionally further contain adhesives, etc.

[0115] For information on solid electrolyte particles and binders, please refer to the above description.

[0116] The thickness of the solid electrolyte layer is not particularly limited, and can be, for example, greater than 0.1 μm and less than 1000 μm.

[0117] Positive electrode active material layer

[0118] The positive electrode active material layer contains at least a positive electrode active material, and may optionally further contain a solid electrolyte, conductive additives, binders, etc.

[0119] The positive electrode active material is not particularly limited and can be, for example, an oxide active material. Oxide active materials used in lithium-ion batteries can be, for example, LiCoO2, LiMnO2, Li2NiMn3O8, LiVO2, LiCrO2, LiFePO4, LiCoPO4, LiNiO2, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, etc. In addition, a coating containing Li ion-conducting oxides (e.g., LiNbO3, etc.) can be formed on the surface of these active materials.

[0120] The content of the positive electrode active material in the positive electrode active material layer is not particularly limited.

[0121] For information on solid electrolytes, conductive additives, and adhesives, please refer to the above description.

[0122] The thickness of the positive electrode active material layer is not particularly limited, and can be, for example, greater than 0.1 μm and less than 1000 μm.

[0123] Positive current collector layer

[0124] The positive electrode current collector layer can be in the form of foil, plate, mesh, stamped metal, foam, etc. The positive electrode current collector layer can be metal foil or metal mesh, and particularly can be metal foil. The positive electrode current collector layer can be made of multiple foils.

[0125] The metals constituting the positive electrode current collector layer can be copper, nickel, chromium, gold, platinum, silver, aluminum, iron, titanium, zinc, cobalt, stainless steel, etc., and the positive electrode current collector layer can especially contain aluminum.

[0126] For purposes such as adjusting resistance, a coating can be formed on the surface of the positive current collector layer. Furthermore, the positive current collector layer can also be formed by plating or vapor-depositing any of the aforementioned metals onto a metal foil or substrate. Additionally, when made of multiple metal foils, the positive current collector layer may include a layer interposed between these metal foils.

[0127] The thickness of the positive current collector layer is not particularly limited, and can be, for example, 0.1 μm or more, or 1 μm or more, or less than 1 mm, or less than 100 μm.

[0128] Other components

[0129] A battery can be a battery in which the above-described components are housed within a casing. Any known battery casing can be used as said casing. Furthermore, multiple batteries can be electrically connected in any manner and stacked in any manner to form a battery pack. In this case, the battery pack can be housed within a known battery casing. A battery may also include other obvious components, such as necessary terminals. The shape of a battery can be, for example, coin-shaped, laminated (bag-shaped), cylindrical, rectangular, etc.

[0130] The method of manufacturing the battery of this disclosure is not particularly limited, and includes, for example, forming an electrode active material layer comprising an electrode hybrid material according to this disclosure.

[0131] An example of a method for forming an electrode active material layer comprising an electrode hybrid material is a method in which constituent materials (such as electrode active material composite particles, etc.) are mixed to obtain an electrode hybrid material, and then the obtained electrode hybrid material is formed by dry forming or wet forming.

[0132] The method of manufacturing the battery disclosed herein may further include sequentially stacking a negative electrode current collector layer, a negative electrode active material layer, a solid electrolyte layer, a positive electrode active material layer, and a positive electrode current collector layer to form an electrode stack.

[0133] Other components (such as terminals) can be attached to the electrode stack as needed. The electrode stack is then housed in a battery case and sealed to obtain the battery.

[0134] Example

[0135] Synthesis of composite particles for electrode active materials

[0136] Provide complex

[0137] First, 1 g of porous carbon material was placed in the furnace tube of a CVD apparatus, and the pressure inside the furnace tube was reduced before heating to 500°C. Next, an oxygen line was inserted into a container containing tetraethoxysilane (TEOS), and oxygen was bubbled through the TEOS, thereby introducing oxygen containing TEOS vapor into the furnace tube. This process was maintained for 6 hours to prepare a composite containing silica (SiO2) within the porous carbon material. The furnace tube was then cooled, its interior was purged with argon, and the resulting composite was recovered.

[0138] Reduction of silicon oxide

[0139] The composite and Mg alloy were placed in a reaction vessel. Next, the reaction vessel was placed in a vacuum furnace, and the interior of the furnace was evacuated using a rotary pump while the temperature was raised to 650°C over one hour. The reaction vessel was then heated at this temperature for 10 hours. This process reduced SiO2 to prepare an electrode active material composite particle precursor containing silicon (Si) and magnesium oxide (MgO) in a porous carbon material. After cooling in the vacuum furnace, the resulting electrode active material composite particle precursor was recovered.

[0140] Removal of magnesium oxide

[0141] Next, 1 g of the electrode active material composite particle precursor and 100 mL of 6% hydrochloric acid were placed in a beaker and stirred for 1 hour. The mixture was filtered under reduced pressure and then dried under vacuum. This yielded the electrode active material composite particles. In the obtained electrode active material composite particles, voids were formed between Si and the porous carbon material within the pores filled with Si, and the silicon in the electrode active material composite particles was also porous, thus producing porous silicon.

[0142] Formation of negative electrode active material layer

[0143] Butyl butyrate, a 5% by weight butyl butyrate solution of polyvinylidene fluoride (PVDF)-based binder, vapor-grown carbon fiber (VGCF) as a conductive additive, the obtained electrode active material composite particles, and Li2S-P2S5 glass-ceramic as a sulfide solid electrolyte were placed in a polypropylene container and stirred for 30 seconds using an ultrasonic disperser (UH-50, manufactured by SMT Corporation). Next, the container was vibrated for 30 minutes in an oscillator (TTM-1, manufactured by Sibata Scientific Technology Ltd.) to obtain a negative electrode composite slurry. The obtained negative electrode composite slurry was applied to a copper (Cu) foil used as the negative electrode current collector layer using a coater via a doctor blade method, and then dried on a hot plate heated to 100°C for 30 minutes, thereby forming a negative electrode active material layer on the negative electrode current collector layer.

[0144] Formation of solid electrolyte layer

[0145] A 5% by weight heptane solution of heptane and butadiene rubber (BR) based adhesive, along with Li2S-P2S5 glass-ceramic as a sulfide solid electrolyte, was placed in a polypropylene container and stirred for 30 seconds using an ultrasonic disperser (UH-50, manufactured by SMT Corporation). Next, the container was vibrated in an oscillator (TTM-1, manufactured by Shibata Scientific Co., Ltd.) for 30 minutes to obtain a solid electrolyte slurry. The obtained solid electrolyte slurry was applied to an aluminum (Al) foil used as a release sheet using a coater via a doctor blade method. The Al foil coated with the solid electrolyte slurry was dried on a hot plate heated to 100°C for 30 minutes to form a solid electrolyte layer. Three solid electrolyte layers were manufactured.

[0146] Formation of positive electrode active material layer

[0147] A 5% by weight butyl butyrate solution, a polyvinylidene fluoride (PVDF) based binder, and LiNi with an average particle size of 6 μm as the positive electrode active material were used. 1 / 3 Co 1 / 3 Mn 1 / 3 O2, Li2S-P2S5 glass-ceramic as a sulfide solid electrolyte, and VGCF as a conductive additive were placed in a polypropylene container, and the mixture was stirred for 30 seconds using an ultrasonic disperser (UH-50, manufactured by SMT Corporation). Next, the container was vibrated in an oscillator (TTM-1, manufactured by Shibata Scientific Co., Ltd.) for 3 minutes, stirred with an ultrasonic disperser for 30 seconds, and further vibrated in the oscillator for 3 minutes to obtain a positive electrode mixture slurry. The obtained positive electrode mixture slurry was applied to an Al foil (manufactured by Showa Denko Corporation) as the positive electrode current collector layer using a coater via a doctor blade method. The Al foil coated with the positive electrode mixture slurry was dried on a hot plate heated to 100°C for 30 minutes to form a positive electrode active material layer on the positive electrode current collector layer.

[0148] Battery manufacturing

[0149] The negative electrode current collector layer, the negative electrode active material layer, and the first solid electrolyte layer are sequentially stacked. Note that the solid electrolyte layer should be stacked such that the side without the Al foil faces the negative electrode active material layer. The stack is then placed in a roller press and pressed at a pressing temperature of 25°C and a pressing pressure of 60 kN / cm to obtain a densified negative electrode stack.

[0150] The positive electrode current collector layer, the positive electrode active material layer, and the second solid electrolyte layer are sequentially stacked. Note that the solid electrolyte layer should be stacked such that the side without the Al foil faces the positive electrode active material layer. The stack is then placed in a roller press and pressed at a pressing temperature of 165°C and a pressing pressure of 100 kN / cm to obtain the positive electrode stack.

[0151] The area of ​​the negative electrode stack is larger than that of the positive electrode stack.

[0152] The Al foil, used as a release sheet, is peeled off from the surface of the first solid electrolyte layer. A third solid electrolyte layer is then laminated onto the first solid electrolyte layer of the thus exposed negative electrode laminate. This laminate is placed in a planar uniaxial press and pre-pressed at 100 MPa for 10 seconds at 25°C. The Al foil is then peeled off from the third solid electrolyte layer to obtain a negative electrode laminate on which a third solid electrolyte layer is further laminated.

[0153] The Al foil, used as a release sheet, is peeled off from the surface of the second solid electrolyte layer. This second solid electrolyte layer is then laminated onto the third solid electrolyte layer. The laminate is placed in a planar uniaxial press and pressed for 1 minute at a pressing temperature of 120°C and a pressing pressure of 200 MPa. Thus, an all-solid-state battery according to Example 1 is obtained.

[0154] Comparative example

[0155] The electrode active material composite particles and the all-solid-state battery containing them according to the comparative example were obtained in the same manner as in the examples, except that, in the composite providing step, monosilane gas was introduced into the furnace tube instead of oxygen containing TEOS vapor.

[0156] Obtain hole size distribution

[0157] For the electrode active material composite particles and porous carbon materials in each example, N2 adsorption isotherms were determined, and then the cumulative pore size distribution and differential pore size distribution were obtained using the BJH (Barrett-Joyner-Halenda) method. In the BJH method determination, a BELSORP MAXX specific surface area and pore size distribution measuring device manufactured by Microtrac was used. The obtained cumulative pore size distribution and differential pore size distribution are shown in [data missing]. Figure 1 and 2 From the hole size distribution obtained in this way, the hole volume of a predetermined size hole can be calculated.

[0158] Evaluation of the increase in constraint pressure

[0159] Using a constraint fixture, each manufactured example battery was constrained under a predetermined constraint pressure, and the increase in constraint pressure was measured when the battery was charged to 4.55 V at a constant current and constant voltage at a 10-hour rate (1 / 10C). The increase in constraint pressure is the difference between the maximum and minimum constraint pressure, and is an indicator of the increase in battery volume.

[0160] The results are shown in Table 1. In Table 1, the values ​​of the increase in constraint pressure in the embodiments are shown as relative values ​​with the value of 1.00 for the comparative examples.

[0161] Table 1

[0162] As shown in Table 1, in the battery of the embodiment containing electrode active material composite particles with pores of less than 10 nm and a pore size of more than 0.22 cc / g, the increase in confinement pressure is small.

[0163] like Figure 1 As shown, the electrode active material composite particles contained in the battery of the embodiment have pores of 2 nm or less in an amount of 0.25 cc / g or more and 0.35 cc / g or less.

[0164] like Figure 1 and 2 As shown, the pore size distribution of the electrode active material composite particles contained in the battery of the embodiment differs from the pore size distribution of the porous carbon material used as a raw material. This indicates that the electrode active material composite particles contained in the battery of the embodiment, in addition to the pores of the porous carbon material that are completely unfilled with silicon and / or not sufficiently filled with silicon, also include voids formed between silicon and porous carbon material in the pores of the silicon-filled porous carbon material, as well as pores of porous silicon (porous silicon).

Claims

1. A composite particle of electrode active material, comprising: Porous carbon materials; and Silicon retained within the porous carbon material, wherein When measured by gas adsorption, the electrode active material composite particles contain pores of less than 10 nm in an amount of more than 0.22 cc / g.

2. The electrode active material composite particles according to claim 1, wherein, When measured by gas adsorption, the electrode active material composite particles contain pores of less than 2 nm in an amount of more than 0.15 cc / g.

3. The electrode active material composite particles according to claim 1, wherein... When measured by gas adsorption, the electrode active material composite particles comprise: The amount of the pores smaller than 10 nm in the range of 0.50 cc / g or more and 0.60 cc / g or less, and The pore size of 2 nm or less is 0.25 cc / g or more and 0.35 cc / g or less.

4. An electrode hybrid material comprising electrode active material composite particles according to any one of claims 1 to 3.

5. A battery comprising an electrode active material layer, wherein the electrode active material layer comprises the electrode hybrid material according to claim 4.

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