Electrode mixture and lithium ion battery

Abstract

To provide an electrode mixture with low expansion during charging, and a lithium-ion battery containing the same.SOLUTION: The electrode alloy contains silicon clathrate active material particles and aluminum fluoride particles. The average particle diameter of the aluminum fluoride particles is 3.0 μm or less. The lithium-ion battery has an electrode active material layer. The electrode active material layer contains the electrode mixture.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an electrode mixture and a lithium-ion battery. [Background technology]

[0002] In recent years, the development of batteries has been actively pursued. For example, in the automotive industry, development of batteries for use in electric vehicles or hybrid vehicles is progressing. Silicon is known as an active material used in batteries, particularly lithium-ion batteries.

[0003] Silicon active materials have a large theoretical capacity and are effective in increasing the energy density of batteries. However, they suffer from the problem of large expansion during charging. It is known that the use of silicon clathrate active materials as silicon active materials can suppress expansion during charging.

[0004] For example, Patent Document 1 discloses a silicon clathrate active material having a silicon clathrate type II crystalline phase, voids inside the primary particles, and a void volume of voids having a pore diameter of 100 nm or less of 0.05 cc / g or more and 0.15 cc / g or less. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-158004 Summary of the Invention [Problem to be solved by the invention]

[0006] Although silicon clathrate active materials can suppress expansion during charging compared to ordinary silicon active materials, there is a demand for further suppression of expansion of silicon clathrate active materials during charging.

[0007] The present disclosure aims to provide an electrode mixture that exhibits small expansion during charging, and a lithium-ion battery that includes such an electrode mixture. [Means for solving the problem]

[0008] The present inventors have found that the above problems can be solved by the following means. <Aspect 1> An electrode mixture comprising silicon clathrate active material particles and aluminum fluoride particles, the aluminum fluoride particles having an average particle size of 3.0 μm or less. <Aspect 2> 2. The electrode mixture according to aspect 1, wherein the aluminum fluoride particles have an average particle size of 0.1 μm or more and 2.5 μm or less. <Aspect 3> 3. The electrode mixture according to aspect 2, wherein the aluminum fluoride particles have an average particle size of 0.8 μm or more and 1.8 μm or less. <Aspect 4> 4. The electrode mixture according to any one of aspects 1 to 3, wherein the ratio of the average particle size of the aluminum fluoride particles to the average particle size of the silicon clathrate active material particles is 2.5 or less. <Aspect 5> The electrode mixture according to any one of aspects 1 to 4, wherein, when a cross section of the electrode mixture is observed by SEM-EDX measurement, the ratio of the content of the aluminum fluoride particles to the content of the silicon clathrate active material particles is less than 2.0 area %. <Aspect 6> An electrode active material layer is provided, and The electrode active material layer contains the electrode mixture according to any one of aspects 1 to 5. Lithium-ion battery. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to provide an electrode mixture that expands little during charging, and a lithium ion battery that includes such an electrode mixture. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a graph showing the relationship between the average particle size of aluminum fluoride particles and the expansion rate of a battery. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described in detail. Note that the present disclosure is not limited to the following embodiments, and various modifications can be made within the scope of the present disclosure.

[0012] 《Electrode composite material》 The electrode mixture of the present disclosure contains silicon clathrate active material particles and aluminum fluoride particles, and the aluminum fluoride particles have an average particle size of 3.0 μm or less.

[0013] In the context of the present disclosure, an "electrode" may be a positive electrode or a negative electrode, and is particularly preferably a negative electrode.

[0014] In the present disclosure, a "composite" refers to a composition that can constitute an electrode active material layer either as is or by further containing other components. Also, in the present disclosure, a "composite slurry" refers to a slurry that contains a "composite" and a dispersion medium and that can be applied and dried to form an electrode active material layer.

[0015] An example of a method for obtaining silicon clathrate active material particles is a method for removing sodium from a sodium-silicon (NaSi) alloy. The present inventors have developed a technology for removing sodium from a NaSi alloy by reacting the NaSi alloy with aluminum fluoride.

[0016] In this regard, the present inventors have found that the electrode composite obtained using this technology has room for improvement in terms of the effect of suppressing expansion during charging. Specifically, without intending to be bound by any theory, they have found that in the electrode composite obtained using this technology, the silicon clathrate active material particles are not uniformly charged due to the presence of insulating aluminum fluoride particles remaining, which may result in significant expansion.

[0017] In contrast, the electrode mixture of the present disclosure has aluminum fluoride particles with a small average particle size of 3.0 μm or less, which is thought to prevent uniform charging of the silicon clathrate active material particles and suppress expansion during charging.

[0018] <Silicon clathrate active material particles> The electrode mix of the present disclosure includes silicon clathrate active material particles.

[0019] The average particle size of the silicon clathrate active material particles may be 0.4 μm or more, 0.6 μm or more, 0.8 μm or more, 0.9 μm or more, 1.0 μm or more, or 1.1 μm or more, and may be 2.0 μm or less, 1.8 μm or less, 1.6 μm or less, 1.5 μm or less, 1.4 μm or less, or 1.3 μm or less.

[0020] The average particle size of the silicon clathrate active material particles can be determined by observation with an electron microscope such as a SEM, and is determined, for example, as the average value of the equivalent circle diameters (equivalent circle area diameters) of a plurality of silicon clathrate active material particles. The number of samples is preferably large, for example, 20 or more, or may be 50 or more, or may be 100 or more.

[0021] <Aluminum fluoride particles> The electrode mix of the present disclosure includes aluminum fluoride particles.

[0022] The average particle size of the aluminum fluoride particles is 3.0 μm or less. The average particle size of the aluminum fluoride particles may be 0.1 μm or more, 0.3 μm or more, 0.5 μm or more, 0.6 μm or more, 0.7 μm or more, 0.8 μm or more, or 0.9 μm or more, or may be 2.7 μm or less, 2.5 μm or less, 2.3 μm or less, 2.1 μm or less, 2.0 μm or less, 1.9 μm or less, 1.8 μm or less, 1.7 μm or less, 1.6 μm or less, or 1.5 μm or less.

[0023] The average particle size of aluminum fluoride particles can be determined by observation with an electron microscope such as a SEM, and is determined, for example, as the average of the equivalent circle diameters of a plurality of aluminum fluoride particles. The number of samples is preferably large, for example, 20 or more, or may be 50 or more, or may be 100 or more.

[0024] The ratio of the average particle size of the aluminum fluoride particles to the average particle size of the silicon clathrate active material particles (AlF3 / Si (particle size)) may be 2.5 or less, and may be 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, or 0.8 or more, or 2.3 or less, 2.1 or less, 1.9 or less, 1.7 or less, 1.5 or less, 1.4 or less, or 1.3 or less.

[0025] The ratio of the content of the aluminum fluoride particles to the content of the silicon clathrate active material particles (AlF3 / Si (area)) may be less than 2.0 area %, and may be 0.1 area % or more, 0.5 area % or more, or 1.0 area % or more, and may be 1.9 area % or less, 1.8 area % or less, or 1.7 area % or less.

[0026] The AlF3 / Si (area) can be calculated by observing the cross section of the electrode composite using a scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX) and calculating the ratio of the area of ​​the range showing aluminum fluoride particles to the area of ​​the range showing silicon clathrate active material particles.

[0027] The silicon clathrate active material particles of the present disclosure can be obtained by any method, exemplified by a method of removing sodium from a sodium silicon (NaSi) alloy.

[0028] Specifically, a silicon source is reacted with a sodium source such as sodium hydride to prepare a NaSi alloy, and then the thus-prepared NaSi alloy is reacted with aluminum fluoride particles as a sodium trap to prepare silicon clathrate active material particles.

[0029] Unreacted aluminum fluoride particles from the above reaction can be used as the aluminum fluoride particles of the present disclosure. Also, commercially available aluminum fluoride particles or aluminum fluoride particles prepared by a conventional method can be used as the aluminum fluoride particles of the present disclosure.

[0030] The aluminum fluoride particles may be subjected to a particle size adjustment process such that the average particle size falls within the range of the present disclosure. Examples of particle size adjustment processes include, but are not limited to, sieving.

[0031] The electrode mixture of the present disclosure can be prepared by mixing the silicon clathrate active material particles thus obtained and a material containing aluminum fluoride particles by any method.

[0032] Lithium-ion battery The lithium-ion battery of the present disclosure may be a liquid-based battery or a solid-state battery. In the context of the present disclosure, the term "solid-state battery" refers to a battery that uses at least a solid electrolyte as an electrolyte. Therefore, a solid-state battery may use a combination of a solid electrolyte and a liquid electrolyte as an electrolyte. Alternatively, the solid-state battery of the present disclosure may be an all-solid-state battery, i.e., a battery that uses only a solid electrolyte as an electrolyte.

[0033] The lithium ion battery of the present disclosure has an electrode active material layer, and the electrode active material layer contains the electrode mixture of the present disclosure. In particular, the lithium ion battery of the present disclosure may have a negative electrode mixture that is the electrode mixture of the present disclosure, in which case the lithium ion battery may include, in this order, a negative electrode current collector layer, a negative electrode active material layer that contains the electrode mixture of the present disclosure, a solid electrolyte layer, a positive electrode active material layer, and a positive electrode current collector layer.

[0034] The lithium ion battery of the present disclosure can be constrained from both sides of the stacking direction of each of the layers by constraining members such as end plates. Examples of constraining methods include, but are not limited to, a method using the constraining torque of bolts.

[0035] Hereinafter, a method for manufacturing a battery in which the negative electrode mixture is the electrode mixture of the present disclosure will be described.

[0036] <Negative electrode current collector layer> The material used for the negative electrode current collector layer is not particularly limited, and any material that can be used as a negative electrode current collector for a battery can be appropriately adopted. For example, copper, a copper alloy, and copper plated or vapor-deposited with nickel, chromium, carbon, or the like may be used, but is not limited to these.

[0037] The shape of the negative electrode current collector layer is not particularly limited, and examples thereof include foil, plate, mesh, etc. Among these, foil is preferred.

[0038] <Negative electrode active material layer> The negative electrode active material layer contains the electrode mixture of the present disclosure.

[0039] (electrode composite material) The electrode mixture contains silicon clathrate active material particles as a negative electrode active material, and aluminum fluoride particles. For the electrode mixture, reference can be made to the above description of the electrode mixture of the present disclosure.

[0040] The negative electrode active material layer optionally contains a solid electrolyte, a conductive additive, and a binder.

[0041] (solid electrolyte) The material of the solid electrolyte is not particularly limited, and any material that can be used as a solid electrolyte for a lithium ion battery can be used. For example, the solid electrolyte may be a sulfide solid electrolyte.

[0042] Examples of sulfide solid electrolytes include, but are not limited to, amorphous sulfide solid electrolytes, crystalline sulfide solid electrolytes, and argyrodite-type solid electrolytes. Specific examples of sulfide solid electrolytes include Li2S-P2S5-based (Li7P3S 11 , Li3PS4, Li8P2S9, etc.), Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-LiBr-Li2S-P2S5, Li2S-P2S5-GeS2 (Li 13 GeP3S 16 , Li 10 GeP2S 12 ), LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, Li 7-x PS 6-x Cl x etc.; or combinations thereof, but are not limited to these.

[0043] The sulfide solid electrolyte may be glass or crystallized glass (glass ceramic).

[0044] When the negative electrode active material layer contains a solid electrolyte, the mass ratio of the silicon clathrate active material particles to the solid electrolyte in the negative electrode active material layer (mass of the silicon clathrate active material particles:mass of the solid electrolyte) is preferably 85:15 to 30:70, and more preferably 80:20 to 40:60.

[0045] (Conductive additive) The conductive additive is not particularly limited, and may be, for example, VGCF (Vapor Grown Carbon Fiber), acetylene black (AB), Ketjen black (KB), carbon nanotubes (CNT), carbon nanofibers (CNF), or the like, but is not limited thereto.

[0046] (binder) The binder is not particularly limited, and may be, for example, but not limited to, a material such as polyvinylidene fluoride (PVdF), butadiene rubber (BR), or styrene butadiene rubber (SBR), or a combination thereof.

[0047] The thickness of the negative electrode active material layer may be, for example, 0.1 to 1000 μm.

[0048] <Solid electrolyte layer> The solid electrolyte layer includes at least a solid electrolyte. In addition to the solid electrolyte, the solid electrolyte layer may also include a binder, etc., as necessary. For the solid electrolyte and the binder, reference can be made to the above description of the negative electrode active material layer of the present disclosure.

[0049] The thickness of the solid electrolyte layer is, for example, 0.1 to 300 μm, and preferably 0.1 to 100 μm.

[0050] <Cathode active material layer> The positive electrode active material layer is a layer containing a positive electrode active material, and optionally a solid electrolyte, a conductive additive, a binder, and the like.

[0051] The material of the positive electrode active material is not particularly limited. For example, the positive electrode active material may be lithium cobalt oxide (LiCoO), lithium nickel oxide (LiNiO), lithium manganese oxide (LiMnO), LiCo 1 / 3 Ni 1 / 3 Mn 1 / 3 O2, Li 1+x Mn 2-x-y Heteroelement-substituted Li-Mn spinel with a composition represented by MyO4 (M is one or more metal elements selected from Al, Mg, Co, Fe, Ni, and Zn), lithium titanate (Li x TiO y ), lithium metal phosphate (LiMPO4, M is one or more metals selected from Fe, Mn, Co, and Ni), etc., but are not limited to these.

[0052] The positive electrode active material may have a coating layer. The coating layer is a layer containing a substance that has lithium ion conductivity, low reactivity with the positive electrode active material and solid electrolyte, and can maintain the shape of the coating layer without flowing even when in contact with the active material and solid electrolyte. Specific examples of materials that constitute the coating layer include LiNbO3 and Li4Ti5O 12 , Li3PO4, etc., but are not limited to these.

[0053] The positive electrode active material may be, for example, particulate. The average particle size (D50) of the positive electrode active material is not particularly limited, but may be, for example, 10 nm or more, or 100 nm or more. On the other hand, the average particle size (D50) of the positive electrode active material is, for example, 50 μm or less, or may be 20 μm or less. The average particle size (D50) can be calculated, for example, from measurements using a laser diffraction particle size distribution analyzer or a scanning electron microscope (SEM).

[0054] For the solid electrolyte, the conductive additive, and the binder, reference can be made to the above descriptions regarding the negative electrode active material layer of the present disclosure.

[0055] When the positive electrode active material layer contains a solid electrolyte, the mass ratio of the positive electrode active material to the solid electrolyte in the positive electrode active material layer (mass of the positive electrode active material: mass of the solid electrolyte) is preferably 85:15 to 30:70, and more preferably 80:20 to 50:50.

[0056] The thickness of the positive electrode active material layer is, for example, 0.1 μm to 1000 μm, preferably 1 μm to 100 μm, and more preferably 30 μm to 100 μm.

[0057] <Positive electrode current collector layer> The material used for the positive electrode current collector layer is not particularly limited, and any material that can be used as a positive electrode current collector for a battery can be appropriately adopted. Examples of the material include, but are not limited to, SUS, nickel, chromium, gold, platinum, aluminum, iron, titanium, zinc, and the like, as well as these metals plated or vapor-deposited with nickel, chromium, carbon, and the like.

[0058] The shape of the positive electrode current collector layer is not particularly limited, and examples thereof include foil, plate, mesh, etc. Among these, foil is preferred. [Example]

[0059] <<Synthesis of silicon clathrate active material particles>> <Alloying> (Comparative Example 1) Si powder (Kojundo Kagaku, SIEPB32) was prepared as a silicon (Si) source. This Si powder and metallic lithium (Li) were weighed out at a molar ratio of Li / Si = 4.0, and the weighed Si powder and Li were mixed in a mortar in an argon atmosphere to obtain a lithium silicon (LiSi) alloy. The obtained LiSi alloy was reacted with ethanol in an argon atmosphere and treated with hydrogen fluoride (HF) to obtain Si powder with voids inside the primary particles, i.e., Si powder with a porous structure.

[0060] A sodium-silicon (NaSi) alloy was produced using porous Si powder and sodium hydride (NaH) as a sodium (Na) source. The NaH used was previously washed with hexane. NaH and porous Si powder were weighed out in a molar ratio of 1.05:1, and the weighed NaH and porous Si powder were mixed using a cutter mill. The resulting mixture was heated in a heating furnace under an argon atmosphere at 400°C for 40 hours to obtain a powdered NaSi alloy. <Clathrate>

[0061] The resulting NaSi alloy and aluminum fluoride (AlF3) particles were weighed out at a molar ratio of 1:0.35, and the weighed NaSi alloy and AlF3 particles were mixed using a cutter mill to obtain a reaction raw material. The resulting powdered reaction raw material was placed in a stainless steel reaction vessel and heated in a heating furnace under an argon atmosphere at 310°C for 60 hours to react, thereby obtaining a silicon clathrate. The resulting silicon clathrate was acid-washed using a mixed solvent of HNO3 and HO in a volume ratio of 90:10 to remove by-products from the reaction product. After washing, the mixture was filtered, and the filtered solid was dried at 120°C for 3 hours or more to obtain a powdered silicon clathrate. The resulting silicon clathrate was then washed with a 3 wt% HF solution, filtered, and dried at 120°C for 3 hours or more to obtain silicon clathrate active material particles of Comparative Example 1. The unreacted AlF3 particles were used as the AlF3 particles of Comparative Example 1. The surface of the silicon clathrate active material particles may contain a coating or impurities containing O, C, or N elements.

[0062] Example 1 Silicon clathrate active material particles and AlF particles of Example 1 were obtained in the same manner as in Comparative Example 1, except that the alloying temperature was changed to 500°C and the NaSi:AlF (molar ratio) in clathration was changed to 1:0.5. Note that the surfaces of the silicon clathrate active material particles may contain coatings or impurities containing O, C, or N elements.

[0063] Example 2 Except for using AlF particles that had passed through a sieve with a mesh size of 75 μm, the silicon clathrate active material particles and AlF particles of Example 2 were obtained in the same manner as in Example 1. Note that the surface of the silicon clathrate active material particles may contain a coating or impurities containing O, C, or N elements.

[0064] Example 3 Except for using AlF particles that passed through a 75 μm mesh sieve but not a 32 μm mesh sieve, silicon clathrate active material particles and AlF particles of Example 3 were obtained in the same manner as in Example 1. Note that the surface of the silicon clathrate active material particles may contain a coating or impurities containing O, C, or N elements.

[0065] Example 4 Except for using AlF particles that had passed through a sieve with a mesh size of 20 μm, the silicon clathrate active material particles and AlF particles of Example 4 were obtained in the same manner as in Example 1. Note that the surface of the silicon clathrate active material particles may contain a coating or impurities containing O, C, or N elements.

[0066] <<Making a lithium-ion battery>> The lithium ion batteries of each example were fabricated as follows.

[0067] <Preparation of negative electrode mixture> Butyl butyrate, a 5 wt% butyl butyrate solution of polyvinylidene fluoride (PVDF) binder, vapor-grown carbon fiber (VGCF) as a conductive additive, silicon clathrate active material particles and AlF particles, and Li2S-P2S5-based glass ceramic as a sulfide solid electrolyte were added to a polypropylene container and stirred for 30 seconds using an ultrasonic disperser (UH-50, manufactured by SMT Co., Ltd.). Next, the container was shaken for 30 minutes using a shaker (TTM-1, manufactured by Shibata Scientific Co., Ltd.) to obtain a slurry-like negative electrode composite (negative electrode composite slurry).

[0068] <Formation of negative electrode active material layer> The obtained negative electrode composite slurry was applied onto a copper (Cu) foil serving as a negative electrode current collector layer by the blade method using an applicator, and then dried on a hot plate heated to 100°C for 30 minutes to form a negative electrode active material layer on the negative electrode current collector layer.

[0069] <Formation of solid electrolyte layer> Heptane, a 5 wt% heptane solution of butylene rubber (BR) binder, and Li2SP2S5-based glass ceramic as a sulfide solid electrolyte were added to a polypropylene container and stirred for 30 seconds using an ultrasonic disperser (UH-50, manufactured by SMT Co., Ltd.). The container was then shaken for 30 minutes using a shaker (TTM-1, manufactured by Shibata Scientific Co., Ltd.) to obtain a solid electrolyte slurry.

[0070] The obtained solid electrolyte slurry was applied to an aluminum (Al) foil as a release sheet by the blade method using an applicator, and then dried for 30 minutes on a hot plate heated to 100°C to form a solid electrolyte layer. Three solid electrolyte layers were produced.

[0071] <Preparation of Positive Electrode Composite> A polypropylene container is filled with butyl butyrate, a 5 wt% butyl butyrate solution of a PVDF-based binder, and LiNi with an average particle size of 6 μm as the positive electrode active material. 1 / 3 Co 1 / 3 Mn 1 / 3 O2, Li2S-P2S5-based glass ceramic as a sulfide solid electrolyte, and VGCF as a conductive additive were added to a container and stirred for 30 seconds using an ultrasonic disperser (UH-50 manufactured by SMT Co., Ltd.). The container was then shaken for 3 minutes using a shaker (TTM-1 manufactured by Shibata Scientific Co., Ltd.), further stirred for 30 seconds using the ultrasonic disperser, and then shaken for 3 minutes using the shaker to obtain a slurry-like positive electrode composite (positive electrode composite slurry).

[0072] <Formation of Positive Electrode Active Material Layer> The obtained positive electrode mixture slurry was applied onto an Al foil serving as a positive electrode current collector layer by a blade method using an applicator, and then dried on a hot plate heated to 100°C for 30 minutes, thereby forming a positive electrode active material layer on the positive electrode current collector layer.

[0073] <Battery assembly> The positive electrode current collector layer, the positive electrode active material layer, and the first solid electrolyte layer were laminated in this order, and the laminate was set in a roll press and pressed at a pressure of 100 kN / cm and a temperature of 165°C to obtain a positive electrode laminate.

[0074] The negative electrode current collector layer, the negative electrode active material layer, and the second solid electrolyte layer were laminated in this order, and the laminate was set in a roll press and pressed at a pressure of 60 kN / cm and a temperature of 25°C to obtain a negative electrode laminate.

[0075] Furthermore, the aluminum foil serving as a release sheet was peeled off from the surfaces of the solid electrolyte layers of the positive electrode laminate and the negative electrode laminate, and then the aluminum foil serving as a release sheet was peeled off from the third solid electrolyte layer.

[0076] The positive electrode laminate and the negative electrode laminate were stacked together so that the solid electrolyte layer sides of each laminate faced the third solid electrolyte layer, and the stack was placed in a flat uniaxial press and pre-pressed at 100 MPa and 25°C for 10 seconds. Finally, the stack was placed in a flat uniaxial press and pressed for 1 minute at a pressure of 200 MPa and a temperature of 120°C. This produced an all-solid-state battery.

[0077] "evaluation" <Average particle size> The average particle diameters of the silicon clathrate active material particles and AlF3 particles were calculated by taking cross-sectional images of the negative electrode active material layer using a scanning electron microscope (SEM) and analyzing the images. Specifically, the average diameters of the equivalent circle diameters of the silicon clathrate active material particles and AlF3 particles were calculated for 100 or more samples.

[0078] <AlF3 / Si (particle size)> The average particle size of the AlF3 particles was divided by the average particle size of the silicon clathrate active material particles to calculate AlF3 / Si (particle size).

[0079] <AlF3 / Si (area)> The cross section of the obtained negative electrode active material layer was observed by SEM-EDX measurement, and AlF3 / Si (area) was calculated from the ratio of the area of ​​the area showing aluminum fluoride particles to the area of ​​the area showing silicon clathrate active material particles.

[0080] <Expansion amount> The fabricated battery was restrained at a predetermined restraining pressure using a restraining jig, and was charged at a constant current and constant voltage up to 4.55 V at a 10-hour rate (1 / 10C). The increase in restraining pressure was measured and defined as the expansion amount in the present disclosure. The increase in restraining pressure is the difference between the maximum and minimum values ​​of the restraining pressure, and the values ​​in the examples are shown as relative values ​​with the value in Comparative Example 1 set to 100.

[0081] "result" The results of the above evaluations for each example are shown in Table 1. In Table 1, "AlF3 classification" indicates whether classification was performed using a metal sieve and the mesh size of the metal sieve. Also, "Si" indicates silicon clathrate active material particles.

[0082] [Table 1]

[0083] As shown in Table 1, the expansion rates of the batteries of Examples 1 to 4, in which the average particle size of the AlF3 particles was within the range of the present disclosure, were small. The expansion rates of the battery of Example 3, in which the average particle size of the AlF3 particles was 1.2 μm, and the battery of Example 4, in which the average particle size of the AlF3 particles was 0.9 μm, were even smaller, and the expansion rate of the battery of Example 2, in which the average particle size of the AlF3 particles was 1.3 μm, was the smallest.

Claims

1. The active material comprises silicon clathrate active material particles and aluminum fluoride particles, and the aluminum fluoride particles have an average particle size of 3.0 μm or less; Here, the average particle size of the aluminum fluoride particles is determined as an average value of the circle-equivalent diameter by acquiring scanning electron microscope images of 100 or more samples and analyzing the acquired images. Electrode composite material.

2. 2. The electrode mixture according to claim 1, wherein the aluminum fluoride particles have an average particle size of 0.1 μm or more and 2.5 μm or less.

3. 3. The electrode mixture according to claim 2, wherein the aluminum fluoride particles have an average particle size of 0.8 μm or more and 1.8 μm or less.

4. a ratio of an average particle size of the aluminum fluoride particles to an average particle size of the silicon clathrate active material particles is 2.5 or less; Here, the average particle size of the silicon clathrate active material particles is determined as an average value of the circle-equivalent diameter by acquiring scanning electron microscope images of 100 or more samples and analyzing the acquired images. The electrode mixture according to claim 1 .

5. 2. The electrode mixture according to claim 1, wherein, when a cross section of the electrode mixture is observed by SEM-EDX measurement, the ratio of the content of the aluminum fluoride particles to the content of the silicon clathrate active material particles is less than 2.0 area%.

6. An electrode active material layer is provided, and The electrode active material layer contains the electrode mixture according to any one of claims 1 to 5. Lithium-ion battery.

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