Electrode active material composite particle, method for producing the same, electrode mixture, and battery

Abstract

The electrode active material composite particle of the present disclosure comprises a porous carbon material and spherical silicon particles retained within the porous carbon material. The electrode active material composite particle of the present disclosure has pores. A method of the present disclosure for manufacturing the electrode active material composite particle comprises decomposing a halogenated silane on a porous carbon material to produce spherical silicon particles. The electrode composite of the present disclosure comprises the electrode active material composite particle of the present disclosure. The battery of the present disclosure has an electrode active material layer, and the electrode active material layer contains the electrode composite of the present disclosure.

Description

Technology Field

[0001] The present disclosure relates to electrode active material composite particles, a method for manufacturing the same, an electrode composite material, and a battery. Background Technology

[0002] Japanese Patent Publication No. 2024-073597 discloses a composite comprising a porous carbon base and silicon, and an electrode comprising such a composite. Japanese Patent Publication No. 2024-073597 discloses a method of embedding silicon within a porous carbon base by chemical vapor deposition (CVD) technology using silane gas. The problem to be solved

[0003] Silicon electrode active materials may expand or contract during the charging and discharging of the battery. Consequently, in batteries containing silicon electrode active materials, volume changes accompanying such expansion and contraction may occur. Even in electrode active material composites containing porous carbon materials and silicon, there is room for improvement in terms of suppressing such volume changes in the battery.

[0004] The present disclosure aims to provide electrode active material composite particles capable of suppressing volume change of a battery, a method for manufacturing the same, an electrode composite material comprising such electrode active material composite particles, and a battery comprising such electrode composite material. means of solving the problem

[0005] The initiators of this case have discovered that the above problem can be solved by the following means.

[0006] <Mode 1>

[0007] porous carbon materials, and

[0008] Spherical silicon particles retained within the above porous carbon material

[0009] Includes, and also

[0010] having craftsmanship,

[0011] Electrode active material composite particle.

[0012] <Mode 2>

[0013] The electrode active material composite particle described in Embodiment 1, wherein the average particle size of the spherical silicon particles is 0.1 μm or more and 1.0 μm or less.

[0014] <Mode 3>

[0015] An electrode composite comprising electrode active material composite particles described in Embodiment 1 or 2.

[0016] <Mode 4>

[0017] It has an electrode active material layer, and also

[0018] The above electrode active material layer contains the electrode composite material described in Embodiment 3,

[0019] battery.

[0020] <Mode 5>

[0021] A method for manufacturing electrode active material composite particles as described in Embodiment 1 or 2, comprising decomposing a halogenated silane on the porous carbon material to produce the spherical silicon particles. Effects of the invention

[0022] According to the present disclosure, electrode active material composite particles capable of suppressing volume change of a battery and a method for manufacturing the same, an electrode composite material comprising such electrode active material composite particles, and a battery comprising such electrode composite material can be provided. Brief explanation of the drawing

[0023] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, and like reference numerals denote like elements. Figure 1 is a cross-sectional SEM image of the electrode active material composite particle of the example. Figure 2 is a graph showing the cumulative pore distribution of the electrode active material composite particles and porous carbon material of the example. Figure 3 is a graph showing the fine pore distribution of the electrode active material composite particles and porous carbon material of the example. Figure 4 is a cross-sectional SEM image of the electrode active material composite particle of the comparative example. Specific details for implementing the invention

[0024] The embodiments of the present disclosure are described in detail below. Furthermore, the present disclosure is not limited to the embodiments described below, but may be implemented with various modifications within the scope of the purpose of the disclosure.

[0025] Electrode active material composite particles

[0026] The electrode active material composite particles of the present disclosure comprise a porous carbon material and spherical silicon particles retained within the porous carbon material. The electrode active material composite particles of the present disclosure have pores.

[0027] The present disclosure parties have discovered that the electrode active material composite particles of the present disclosure can suppress the volume change of a battery associated with the expansion and contraction of silicon particles during charging and discharging of the battery.

[0028] For this reason, although we do not intend to be bound by any specific theory, it is estimated as follows. That is, in electrode active material composite particles having pores, it is thought that the pores can mitigate the effects of expansion and contraction of silicon particles during the charging and discharging of the battery. Spherical silicon particles are thought to expand and contract isotropically. Therefore, it is thought that in spherical silicon particles, the effect of mitigating the aforementioned expansion and contraction by the pores is greater than in non-spherical silicon particles, which are prone to localized expansion, and thus the volume change of the battery can be suppressed.

[0029] The “electrode active material” may be a “positive electrode active material” or a “negative electrode active material,” and in particular, may be a “negative electrode active material.”

[0030] Hereinafter, each element constituting the electrode active material composite particle of the present disclosure will be described.

[0031] porous carbon material

[0032] The electrode active material composite particle of the present disclosure comprises a porous carbon material. The porous carbon material retains silicon within its pores.

[0033] The porous carbon material is not particularly limited. The porous carbon material may be, for example, activated carbon. The porous carbon material may be a material having interconnected pores. An example of such a material is the commercially available Kunobel (registered trademark) MH-00.

[0034] The pore diameter and pore volume of the porous carbon material are not particularly limited. The porous carbon material may have pores of 10 nm or less when measured by the gas adsorption method, 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 may also have 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 fine pore distribution by gas adsorption of a porous carbon material may be located at 1 nm or more, 2 nm or more, 3 nm or more, or 4 nm or more, and may also be located at 10 nm or less, 7 nm or less, 5 nm or less, or 4 nm or less.

[0036] The gas adsorption method is not particularly limited; for example, after measuring the N2 adsorption isotherm, the cumulative pore distribution and the fine pore distribution may be obtained by the BJH (Barrett-Joyner-Halenda) method. In this case, the BELSORPMAXX, a specific surface area and pore distribution measuring device manufactured by Microtrax, can be used. From the cumulative pore distribution and fine pore distribution obtained in this way, the pore diameter and pore volume can be determined. The pore volume of the electrode active material composite particles described later can also be determined by the same method.

[0037] Spherical silicon particles

[0038] The electrode active material composite particles of the present disclosure comprise spherical silicon particles retained within a porous carbon material. By doing so, the effect of mitigating the expansion and contraction of silicon particles due to pores can be greatly enhanced, and thus, changes in the volume of the battery can be suppressed.

[0039] The silicon is not particularly limited and, for example, may be one produced using a halogenated silane as a raw material by the method described below.

[0040] In relation to the present disclosure, "spherical" means a shape with an aspect ratio of 3 or less. Accordingly, the aspect ratio of the silicon particle may be 3.0 or less, 2.5 or less, 2.0 or less, 1.5 or less, 1.3 or less, 1.2 or less, or 1.1 or less, and may also be 1.0.

[0041] The aspect ratio may be, for example, the average value of the values ​​calculated by dividing the longest width by the shortest width among the widths between the mutually opposing ends of particles in a cross-sectional SEM image of electrode active material composite particles acquired by a scanning electron microscope (SEM).

[0042] For example, a cross-sectional SEM image of electrode active material composite particles can be obtained by the following method. That is, first, electrode active material composite particles and zinc powder are mixed, and pellets are formed using a press machine. A cross-sectional SEM image is obtained for a sample obtained by cross-sectionally processing this pellet using a cross-section polisher.

[0043] The average particle size of the spherical silicon particles may be 0.1 μm or more and 1.0 μm or less. This average particle size may be 0.1 μm or more, 0.2 μm or more, or 0.3 μm or more, and may also be 1.0 μm or less, 0.8 μm or less, 0.6 μm or less, 0.5 μm or less, 0.4 μm or less, 0.3 μm or less, or 0.2 μm or less. By doing so, the volume change of the battery can be effectively suppressed.

[0044] The average particle size can be obtained by observation using an electron microscope such as a scanning electron microscope (SEM), for example, as the average value of the maximum ferret diameters of each of a plurality of particles. It is preferable that the number of samples be large, for example, 20 or more, 50 or more, or 100 or more. The average particle size can be appropriately adjusted, for example, by changing the manufacturing conditions of the silicon particles.

[0045] Specifically, the average particle size can be measured by the following method. That is, first, electrode active material composite particles and zinc powder are mixed, and a pellet is formed using a press machine. The sample obtained by cross-sectional processing of this pellet with a cross-section polisher is observed using SEM, and the particle size of the silicon particles can be measured using a scale bar at each magnification. Then, the particle size of multiple silicon particles can be measured, and their average values ​​can be calculated.

[0046] In the electrode active material composite particles of the present disclosure, the mass ratio of spherical silicon particles to the porous carbon material may be 0.1 or more and 10.0 or less. This mass ratio may 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 may 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 particles to porous carbon material may be 1:1.

[0047] craftsmanship

[0048] The electrode active material composite particle of the present disclosure has pores.

[0049] The pore volume is not particularly limited. In the method for manufacturing electrode active material composite particles described below, for example, when three alumina boats are used, the pore volumes of the electrode active material composite particles obtained from the alumina boats at upstream, midstream, and downstream positions with respect to the flow of Ar containing halogenated silane vapor may be equal or different.

[0050] The pore volume of the electrode active material composite particles obtained from the alumina boat located upstream may be 500 cc / g or more, 600 cc / g or more, 700 cc / g or more, or 750 cc / g or more, and may also be 900 cc / g or less, 850 cc / g or less, or 800 cc / g or less.

[0051] The pore volume of the electrode active material composite particles obtained from the alumina boats located in the middle and downstream areas may be 300 cc / g or more, 400 cc / g or more, or 500 cc / g or more, respectively, and may also be 700 cc / g or less, 600 cc / g or less, or 5500 cc / g or less.

[0052] The maximum value of the peak in the fine pore distribution by gas adsorption of electrode active material composite particles may be located at 1 nm or more, 2 nm or more, 3 nm or more, or 4 nm or more, and may also be located at 10 nm or less, 7 nm or less, 5 nm or less, or 4 nm or less.

[0053] Method for manufacturing electrode active material composite particles

[0054] The present disclosure method for manufacturing electrode active material composite particles comprises decomposing a halogenated silane on a porous carbon material to produce spherical silicon particles.

[0055] The method for decomposing halogenated silanes on porous carbon materials is not particularly limited, and, for example, a method by chemical vapor deposition (CVD) can be used. Specifically, the following method is exemplified. That is, first, an alumina boat containing porous carbon materials is installed inside a tubular furnace. The inside of the tubular furnace is replaced with argon (Ar) and heated. At this time, the flow rate of Ar may be appropriately changed, and in particular, the flow rate may be lowered. Then, the Ar line is transferred from the tubular furnace to a container containing halogenated silanes, Ar is bubbled into the halogenated silanes, and Ar containing halogenated silane vapor is introduced into the tubular furnace. At this time, the introduction of hydrogen is also initiated simultaneously. By maintaining this state, halogenated silanes can be decomposed on the porous carbon material. And thereby, spherical silicon particles are produced.

[0056] Halogenated silanes are not particularly limited and may be, for example, tetrachlorosilane, trichlorosilane, dichlorosilane, monochlorosilane, and in particular tetrachlorosilane (TCS). By doing so, electrode active material composite particles containing spherical silicon particles can be effectively manufactured.

[0057] The heating temperature is not particularly limited and, for example, may be 300°C or higher, 500°C or higher, 600°C or higher, or 700°C or higher, or may be 1000°C or lower, 900°C or lower, 800°C or lower, or 700°C or lower.

[0058] The time for introducing Ar gas and hydrogen, including silane halide vapor, into the tubular furnace is not particularly limited and, for example, may be 3 hours or more, 5 hours or more, 6 hours or more, or 7 hours or more, or 30 hours or less, 20 hours or less, 15 hours or less, 10 hours or less, 8 hours or less, or 7 hours or less.

[0059] Electrode composite

[0060] The electrode composite of the present disclosure comprises electrode active material composite particles of the present disclosure. The electrode composite may optionally include a solid electrolyte, a conductivity aid, a binder, etc.

[0061] In relation to the present disclosure, "electrode composite" refers to a composition that can form an electrode active material layer either as is or by additionally containing other components. Also, in relation to the present disclosure, "electrode composite slurry" refers to a slurry that includes a dispersion medium in addition to the "electrode composite" and can form an electrode active material layer by coating and drying accordingly.

[0062] With respect to the present disclosure, the “electrode composite” may be a “positive electrode composite”, a “negative electrode composite”, and especially a “negative electrode composite”.

[0063] Hereinafter, each element constituting the electrode composite of the present disclosure will be described.

[0064] Electrode active material composite particles

[0065] For electrode active material composite particles, refer to the above description.

[0066] The content of the electrode active material composite particles in the electrode composite material is not particularly limited and can be appropriately set by considering the desired battery capacity, etc.

[0067] solid electrolyte

[0068] 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. The solid electrolyte may specifically be a sulfide solid electrolyte.

[0069] For example, if the battery is a lithium-ion secondary battery, the solid electrolyte may have lithium-ion conductivity.

[0070] Examples of sulfide solid electrolytes having lithium ion conductivity include solid electrolytes containing Li element, X element (X is at least one of P, As, Sb, Si, Ge, Sn, B, Al, Ga, and In), and S element. Additionally, the sulfide solid electrolyte may further contain at least one of O element and halogen element. Examples of halogen elements include F element, Cl element, Br element, and I element.

[0071] As sulfide solid electrolytes, for example, Li2S-P2S5, Li2S-P2S5-LiI, Li2S-P2S5-GeS2, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-P2S5-LiI-LiBr, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (where m and n are defined numbers. Z is any one of Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Lix MO y (where x and y are defined numbers. M is any of P, Si, Ge, B, Al, Ga, In) can be cited.

[0072] Examples of oxide solid electrolytes having lithium ion conductivity include solid electrolytes containing the element Li, the element Y (Y is at least one of Nb, B, Al, Si, P, Ti, Zr, Mo, W, and S), and the element O. A specific example is Li7La3Zr2O 12 , Li 7-x La3(Zr 2-x Nb x )O 12 (0 ≤ x ≤ 2), Li5La3Nb2O 12 Examples include garnet-type solid electrolytes such as (Li,La)TiO3, (Li,La)NbO3, (Li,Sr)(Ta,Zr)O3, perovskite-type solid electrolytes such as Li(Al,Ti)(PO4)3, Li(Al,Ga)(PO4)3, Nasicon-type solid electrolytes such as Li3PO4, LIPON (a compound in which some of the O in Li3PO4 is substituted with N), and Li-BO-type solid electrolytes such as Li3BO3, a compound in which some of the O in Li3BO3 is substituted with C.

[0073] The content of the solid electrolyte in the electrode composite is not particularly limited and can be appropriately set considering the desired ionic conductivity, etc.

[0074] Challenge Supplements

[0075] The conduction aid may be, for example, a carbon material, metal particles, or a combination thereof. The carbon material may be, for example, a non-fibrous carbon material such as acetylene black (AB) or Ketjenblack (KB); fibrous carbon materials such as vapor-grown carbon fibers (VGCF), carbon nanotubes (CNT), or carbon nanofibers (CNF), or a combination thereof. The metal particles may be, for example, nickel, copper, iron, stainless steel, etc., or a combination thereof.

[0076] The content of the conductive aid in the electrode composite material is not particularly limited and can be appropriately set considering the desired conductivity, etc.

[0077] bookbinder

[0078] The binder may be, for example, a rubber-based binder such as butadiene rubber, hydrogenated butadiene rubber, styrene-butadiene rubber (SBR), hydrogenated styrene-butadiene rubber, nitrile-butadiene rubber, hydrogenated nitrile-butadiene rubber, acrylate-butadiene rubber (ABR), ethylene-propylene rubber; a fluoride-based binder such as polyvinylidene fluoride (PVDF), polyvinylidene-polyhexafluoropropylene copolymer (PVDF-HFP), polytetrafluoroethylene, fluororubber; a polyolefin-based thermoplastic resin such as polyethylene, polypropylene, polystyrene; an imide-based resin such as polyimide, polyamide-imide; an amide-based resin such as polyamide; an acrylic-based resin such as polymethyl acrylate, polyethyl acrylate; a methacrylate-based resin such as polymethyl methacrylate, polyethyl methacrylate; or a combination thereof.

[0079] The binder content in the electrode composite is not particularly limited and can be appropriately set considering the desired binding properties, etc.

[0080] Other ingredients

[0081] The electrode composite material may additionally include components other than those mentioned above, or may not include them.

[0082] battery

[0083] The battery of the present disclosure has an electrode active material layer, and the electrode active material layer contains the electrode composite of the present disclosure. The battery of the present disclosure may have 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 order. In this case, the electrode active material layer containing the electrode composite of the present disclosure may be a negative electrode active material layer, a positive electrode active material layer, or particularly a negative electrode active material layer.

[0084] The battery of the present disclosure may be a liquid-based battery or a solid-state battery, and may be a solid-state battery in particular. Furthermore, with respect to the present disclosure, "solid-state battery" means a battery comprising at least a solid electrolyte as an electrolyte, and thus, the solid-state battery may be a combination of a solid electrolyte and a liquid electrolyte as an electrolyte. In addition, the solid-state battery may be an all-solid-state battery, that is, a battery comprising only a solid electrolyte as an electrolyte.

[0085] The battery of the present disclosure may be a primary battery, a secondary battery, and in particular, a lithium-ion secondary battery.

[0086] The battery of the present disclosure may be restrained by restraining members, such as end plates, from both sides of the stacking direction of each layer. Examples of restraining methods include using the restraining torque of a bolt, but are not limited thereto.

[0087] Hereinafter, each element constituting the battery of the present disclosure is described. In addition, the following is an exemplary case in which the electrode active material layer containing the electrode composite of the present disclosure is a negative electrode active material layer.

[0088] Bu-geuk, entire house floor

[0089] The negative electrode current collector layer may be in the form of a foil, plate, mesh, punched metal, foam, etc. The negative electrode current collector layer may be a metal foil or metal mesh, a carbon sheet, and in particular, a metal foil. The negative electrode current collector layer may be made of multiple foils, sheets, etc.

[0090] The metal constituting the negative electrode current collector layer is not particularly limited and may 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 include at least one metal selected from copper, nickel, and stainless steel.

[0091] For purposes such as adjusting resistance, any coating layer may be formed on the surface of the negative electrode current collector layer. Additionally, the negative electrode current collector layer may be a metal foil or a substrate on which the above-mentioned metal is plated or deposited. Furthermore, if the negative electrode current collector layer is composed of multiple metal foils, any layer may be formed between the multiple metal foils.

[0092] The thickness of the negative electrode current collector layer is not particularly limited and, for example, may be 0.1 μm or more or 1 μm or more, or may be 1 mm or less or 100 μm or less.

[0093] negative electrode active material layer

[0094] The negative electrode active material layer comprises the electrode composite of the present disclosure. For the electrode composite of the present disclosure, reference may be made to the description above. The negative electrode active material layer may be formed by molding the electrode composite of the present disclosure itself into a layer.

[0095] The thickness of the negative electrode active material layer is not particularly limited and, for example, may be 0.1 μm or more and 1000 μm or less.

[0096] solid electrolyte layer

[0097] The solid electrolyte layer comprises at least solid electrolyte particles and may optionally additionally include a binder, etc.

[0098] For solid electrolyte particles and binders, refer to the description above.

[0099] The thickness of the solid electrolyte layer is not particularly limited and, for example, may be 0.1 μm or more and 1000 μm or less.

[0100] positive electrode active material layer

[0101] The positive electrode active material layer comprises at least a positive electrode active material and may optionally additionally include a solid electrolyte, a conductivity aid, a binder, etc.

[0102] The positive electrode active material is not particularly limited and may be, for example, an oxide active material. Oxide active materials used in lithium-ion batteries include, for example, LiCoO2, LiMnO2, Li2NiMn3O8, LiVO2, LiCrO2, LiFePO4, LiCoPO4, LiNiO2, and LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 It may be O2, etc. In addition, a coating layer containing a Li ion-conducting oxide, such as LiNbO3, may be formed on the surface of these active materials.

[0103] The content of the positive electrode active material in the positive electrode active material layer is not particularly limited.

[0104] For solid electrolytes, conductive aids, and binders, refer to the description above.

[0105] The thickness of the positive electrode active material layer is not particularly limited and, for example, may be 0.1 μm or more and 1000 μm or less.

[0106] The entire floor of the main drama house

[0107] The positive electrode current collector layer may be in the form of a foil, plate, mesh, punched metal, foam, etc. The positive electrode current collector layer may be a metal foil or metal mesh, and in particular, may be a metal foil. The positive electrode current collector layer may be composed of multiple foils.

[0108] The metal constituting the positive electrode current collector layer may be copper, nickel, chromium, gold, platinum, silver, aluminum, iron, titanium, zinc, cobalt, stainless steel, etc., and in particular, the positive electrode current collector layer may contain aluminum.

[0109] For purposes such as adjusting resistance, any coating layer may be formed on the surface of the positive electrode current collector layer. Additionally, the positive electrode current collector layer may be a metal foil or substrate on which the above-mentioned metal is plated or deposited. Furthermore, if the positive electrode current collector layer is composed of multiple metal foils, any layer may be formed between the multiple metal foils.

[0110] The thickness of the positive electrode current collector layer is not particularly limited and, for example, may be 0.1 μm or more or 1 μm or more, or 1 mm or less or 100 μm or less.

[0111] Other compositions

[0112] The battery may be one in which each of the above components is housed inside an outer casing. Any known outer casing may be adopted as the outer casing for a battery. Additionally, multiple batteries may be electrically connected and stacked as desired to form a battery cell. In this case, the battery cell may be housed inside a known battery case. The battery may also be equipped with obvious components such as necessary terminals. The shape of the battery may be, for example, coin type, laminate (pouch) type, cylindrical type, prismatic type, etc.

[0113] A method for manufacturing a battery of the present disclosure is not particularly limited and, for example, includes forming an electrode active material layer containing an electrode composite material of the present disclosure.

[0114] An example of a method for forming an electrode active material layer containing an electrode composite is a method of obtaining an electrode composite by mixing constituent materials such as electrode active material composite particles, and then dry molding or wet molding the obtained electrode composite.

[0115] The method for manufacturing a battery of the present disclosure may further include forming an electrode laminate by 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 in this order.

[0116] Other components, such as terminals, are mounted on the electrode laminate as needed. A battery is obtained by housing the electrode laminate in a battery case and sealing it.

[0117] Examples

[0118] Synthesis of electrode active material composite particles

[0119] Three alumina boats containing porous carbon material were installed inside a tubular furnace. The amount of porous carbon material was 0.2 g / boat. At room temperature, the inside of the tubular furnace was purged with argon (Ar). At this time, the flow rate of Ar was 1 L / min. The flow rate of Ar was lowered to 100 mL / min, and the temperature inside the tubular furnace was raised to 700 °C. Subsequently, the Ar line was transferred from the tubular furnace to a container containing tetrachlorosilane (TCS), Ar was bubbled into the TCS, and Ar containing TCS vapor was introduced into the tubular furnace. At this time, the introduction of hydrogen was also started simultaneously. The flow rate of hydrogen was 10 mL / min. After 1 hour, the introduction of Ar containing TCS and hydrogen was stopped. In this way, TCS was decomposed on the porous carbon material, and spherical silicon particles were produced. That is, electrode active material composite particles comprising a porous carbon material and spherical silicon particles retained within the porous carbon material were obtained. Then, only Ar was introduced into the tubular furnace, the tubular furnace was cooled to room temperature, and the obtained electrode active material composite particles were recovered.

[0120] Cross-sectional observation of spherical silicon particles

[0121] Electrode active material composite particles and zinc powder were mixed, and pellets were formed using a press machine. Cross-sectional SEM images were acquired for the samples of these pellets, which were cross-sectionally processed using a cross-section polisher.

[0122] A cross-sectional SEM image obtained is shown in Fig. 1. As shown in Fig. 1, in the electrode active material composite particles of the example, the silicon particles were spherical. In addition, this was the same for the electrode active material composite particles obtained from any of the three alumina boats.

[0123] Thus, it is suggested that spherical silicon particles expand and contract isotropically, and therefore, compared to non-spherical silicon particles which are prone to local expansion, the effect of mitigating the expansion and contraction of silicon particles through pores is greater, and thus, the volume change of the battery can be suppressed.

[0124] Acquisition of crafting distribution

[0125] For the electrode active material composite particles of the example and a porous carbon material for reference, after measuring the N2 adsorption isotherms, the cumulative pore distribution and fine pore distribution were obtained by the BJH (Barrett-Joyner-Halenda) method. For the measurement by the BJH method, a BELSORPMAXX, a specific surface area and pore distribution measuring device manufactured by Microtrax, was used. The obtained cumulative pore distribution and fine pore distribution are shown in Figures 2 and 3, respectively. From the pore distribution obtained in this way, the pore volume was calculated. The results are shown in Table 1. In addition, "upstream," "midstream," and "downstream" in Figures 2 and 3 and Table 1 refer to the positions of three alumina boats relative to the flow of Ar containing TCS vapor, respectively.

[0126]

[0127] Comparative example

[0128] Comparative example electrode active material composite particles were obtained and cross-sectional SEM images were acquired by performing the same procedure as in the example, except that monosilane gas was introduced into the tubular furnace instead of Ar containing TCS vapor, and a cross-sectional SEM image was acquired.

[0129] The acquired cross-sectional SEM image is shown in Fig. 4. As shown in Fig. 4, in the electrode active material composite particles of the comparative example, the silicon particles were so small that it was impossible to observe the shape and measure the average particle size.

Claims

Claim 1 A porous carbon material and a spherical silicon particle retained within the porous carbon material, and also an electrode active material composite particle having pores. Claim 2 In claim 1, the electrode active material composite particle having an average particle size of the spherical silicon particles of 0.1 μm or more and 1.0 μm or less. Claim 3 An electrode composite comprising electrode active material composite particles as described in claim 1 or 2. Claim 4 A battery having an electrode active material layer, wherein the electrode active material layer contains the electrode composite material described in claim 3. Claim 5 A method for manufacturing electrode active material composite particles according to claim 1 or 2, comprising decomposing a halogenated silane on the porous carbon material to produce the spherical silicon particles.

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