Conductive material-containing ethylene carbonate composite, composite active material particles, method for manufacturing an active material layer, and method for manufacturing an electrode laminate module.

Abstract

The present disclosure aims to provide a method for manufacturing an active material layer that has voids and suppresses the electrical isolation of active material particles. [Solution] The conductive material-containing ethylene carbonate composite 120 of this disclosure contains solid ethylene carbonate 122 and a conductive material 124 dispersed in the solid ethylene carbonate 122. Furthermore, the composite active material particles 100 of this disclosure have the conductive material-containing ethylene carbonate composite 120 described in this disclosure and the first active material particles 140.

Description

[Technical Field]

[0001] This disclosure relates to a conductive material-containing ethylene carbonate composite, composite active material particles, a method for manufacturing an active material layer, and a method for manufacturing an electrode laminate module. [Background technology]

[0002] An electrode stack module generally consists of an electrode stack in which a positive electrode current collector layer, a positive electrode active material layer, a separator layer or solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector layer are stacked in this order, and then housed in an outer casing or the like. Si, SiC, etc., which may be contained as negative electrode active material particles in the negative electrode active material layer, expand and contract significantly during charging and discharging, which can cause cracking of the active material layer, leakage of the electrolyte, and a decrease in battery life. Therefore, in recent years, various studies have been conducted to suppress the volume expansion of electrode materials even after repeated charging and discharging, from the standpoint of battery safety.

[0003] For example, Patent Document 1 discloses a composite active material for lithium secondary batteries having voids between Si or a Si alloy and a thin graphite layer, between thin graphite layers, and between Si or a Si alloy, with a void ratio of 2 to 50%. According to the composite active material for lithium secondary batteries described in Patent Document 1, it is possible to produce electrode materials in which volume expansion during charging and volume expansion after repeated charge-discharge cycles are suppressed, and it is possible to produce lithium secondary batteries that exhibit excellent cycle characteristics. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2018-170246 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] In the prior art of increasing the porosity of the active material layer, while the cracking of the active material layer due to expansion and contraction of SiC particles or the like can be alleviated, it is conceivable that the SiC particles or the like become electrically isolated.

[0006] Therefore, an object of the present disclosure is to provide a method for manufacturing an active material layer having voids and suppressing electrical isolation of the active material particles.

Means for Solving the Problems

[0007] The present disclosure achieves the above object by the following means.

[0008] (Aspect 1) A conductive material-containing ethylene carbonate composite containing solid-state ethylene carbonate and a conductive material dispersed in the solid-state ethylene carbonate. (Aspect 2) Composite active material particles having the conductive material-containing ethylene carbonate composite described in Aspect 1 and first active material particles. (Aspect 3) The composite active material particles described in Aspect 2 having second active material particles arranged around them. (Aspect 4) Providing an active material layer precursor containing the composite active material particles described in Aspect 2 or 3, and Dissolving the ethylene carbonate in the composite active material particles, A method for manufacturing an active material layer including this. (Aspect 5) A method for manufacturing an electrode laminate module including the method described in Aspect 4.

Effects of the Invention

[0009] According to the present disclosure, an active material layer having voids and suppressing electrical isolation of the active material particles can be manufactured.

Brief Description of the Drawings

[0010] [Figure 1]Figure 1 is a schematic diagram illustrating this disclosure. [Modes for carrying out the invention]

[0011] The embodiments of this disclosure will be described in detail below. However, this disclosure is not limited to the embodiments described below, and can be implemented in various ways within the scope of the gist of this disclosure. Furthermore, in the description of the drawings, the same elements are denoted by the same reference numerals, and redundant descriptions are omitted.

[0012] <Conductive material-containing ethylene carbonate composite> The conductive material-containing ethylene carbonate composite of this disclosure contains solid ethylene carbonate and a conductive material dispersed in the solid ethylene carbonate.

[0013] Using the above conductive material-containing ethylene carbonate composite, it is possible to manufacture an active material layer that has voids and suppresses the electrical isolation of active material particles.

[0014] Conventional methods suppress the expansion and contraction of the negative electrode active material particles due to charging and discharging by forming voids within the negative electrode active material layer, thereby suppressing the expansion and contraction of the battery. However, the inventors of this case have found that forming voids can lead to the active material particles becoming electrically isolated, which may degrade battery performance.

[0015] In contrast, this disclosure provides an active material layer precursor containing composite active material particles, and dissolves the ethylene carbonate in the composite active material particles. Here, the composite active material particles are coated on the surface of the active material particles with a conductive material-containing ethylene carbonate composite containing ethylene carbonate and a conductive material dispersed in the ethylene carbonate. As a result, the ethylene carbonate on the surface of the composite active material particles dissolves, and voids can be formed on the surface of the active material particles. For example, ethylene carbonate can be dissolved by injecting an electrolyte into the active material layer precursor, but this disclosure is not limited thereto.

[0016] One embodiment of the present disclosure is shown in Figure 1, but the present disclosure is not limited thereto. The composite active material particles 100 comprises a conductive material-containing ethylene carbonate composite 120 containing ethylene carbonate 122 and a conductive material 124 dispersed in the ethylene carbonate 122, a first active material particle 140, and a second active material particle 160, wherein the conductive material-containing ethylene carbonate composite 120 coats the first active material particle 140, and the second active material particle 160 is arranged around it. By injecting an electrolyte, the ethylene carbonate 122 contained in the conductive material-containing ethylene carbonate composite 120 dissolves in the electrolyte, thereby forming a void between the first active material particle 140 and the second active material particle 160. In this case, since the conductive material 124 is dispersed between the first active material particles 140 and the second active material particles 160, it is possible to suppress the electrical isolation of the first active material particles 140 from the second active material particles 160.

[0017] Furthermore, by forming an active material layer using composite active material particles having a conductive material-containing ethylene carbonate composite, and dissolving the ethylene carbonate in the composite active material particles by injecting a solution, the conductive material can be placed in the formed voids, thereby suppressing the electrical isolation of the active material particles.

[0018] Furthermore, since ethylene carbonate is a solid at room temperature (25°C) and is an electrolyte component, it is unnecessary to dry and remove the ethylene carbonate after the formation of the active material layer. Therefore, this disclosure can be effectively utilized even when the entire active material layer formation process is carried out as a dry deposition process.

[0019] In this disclosure, for example, ethylene carbonate can be dispersed in ethylene carbonate by heating it to a temperature above its melting point (36.4°C) to melt the ethylene carbonate, and then adding the conductive material to the dispersed ethylene carbonate using a dispersion device. However, this disclosure is not limited to this. Examples of dispersion devices include homogenizers and the like.

[0020] <Conductive material> In this disclosure, the conductive material is contained in a conductive material-containing ethylene carbonate composite. Alternatively, the conductive material is dispersed in solid ethylene carbonate.

[0021] In this disclosure, the conductive material may be any conductive material known for use in secondary batteries. Specifically, examples of conductive materials include carbon materials such as Ketjenblack (KB), vapor-processed carbon fiber (VGCF), acetylene black (AB), carbon nanotubes (CNT), carbon nanofibers (CNF), carbon black, coke, and graphite. The conductive material may also be a metallic material capable of withstanding the environment in which the battery is used. The conductive material may be used alone or in combination of two or more types. The conductive material may take various forms, such as powder or fibers.

[0022] In this disclosure, the content of the conductive material in the conductive material-containing ethylene carbonate composite is not particularly limited, but may be 0.1% by mass or more, 0.5% by mass or more, 1.0% by mass or more, 3% by mass or more, or 5% by mass or more, and may be 20% by mass or less, 15% by mass or less, 10% by mass or less, 8% by mass or less, or 5% by mass or less.

[0023] ≪Composite active material particles≫ The composite active material particles of this disclosure comprise a conductive material-containing ethylene carbonate composite described in this disclosure and first active material particles. For example, the conductive material-containing ethylene carbonate composite coats the surface of the first active material particles.

[0024] In this disclosure, the composite active material particle may have a second active material particle positioned around it.

[0025] In this disclosure, the coating thickness of the conductive material-containing ethylene carbonate composite is not particularly limited, but may be 3 μm or more, 5 μm or more, 10 μm or more, 20 μm or more, or 30 μm or more, and may be 500 μm or less, 300 μm or less, 200 μm or less, 100 μm or less, or 70 μm or less.

[0026] <Conductive material-containing ethylene carbonate composite> With regard to the conductive material-containing ethylene carbonate composite in the composite active material particles of this disclosure, refer to the above description regarding conductive material-containing ethylene carbonate composite.

[0027] <First and / or second active material particles> The first and / or second active material particles of this disclosure are contained in composite active material particles. With respect to this disclosure, the first and / or second active material particles may be a positive electrode active material or a negative electrode active material, but it is preferable that they be a negative electrode active material that expands and contracts with charging and discharging, as this allows for effective use of the method of this disclosure.

[0028] The material of the positive electrode active material is not particularly limited. Examples of positive electrode active materials include lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium manganese oxide (LiMn2O4), and nickel-cobalt-lithium manganese oxide (NCM:LiCO2). 1 / 3 Ni 1 / 3 Mn 1 / 3 O2), lithium nickel-cobalt aluminum oxide (LiNi 0.8 (CoAl) 0.2 O2), Li 1+x Mn 2-x-y M y This may include, but is not limited to, heteroatom-substituted Li-Mn spinel with a composition represented by O4 (where M is one or more metallic elements selected from Al, Mg, Co, Fe, Ni, and Zn).

[0029] The material of the negative electrode active material is not particularly limited. As the negative electrode active material, for example, it may be metallic lithium, or a material capable of occluding and releasing metal ions such as lithium ions. Examples of the material capable of occluding and releasing metal ions such as lithium ions include, but are not limited to, alloy-based negative electrode active materials, carbon materials, lithium titanate (Li4Ti5O 12 ), silicon carbide (SiC), etc.

[0030] The alloy-based negative electrode active material is not particularly limited, and examples thereof include Si alloy-based negative electrode active materials or Sn alloy-based negative electrode active materials. The Si alloy-based negative electrode active materials include silicon, silicon oxides, silicon carbides, silicon nitrides, etc., or solid solutions thereof. Further, the Si alloy-based negative electrode active materials may contain metal elements other than silicon, such as iron (Fe), cobalt (Co), antimony (Sb), bismuth (Bi), lead (Pb), nickel (Ni), copper (Cu), zinc (Zn), germanium (Ge), indium (In), tin (Sn), titanium (Ti), etc. The Sn alloy-based negative electrode active materials include tin, tin oxides, tin nitrides, etc., or solid solutions thereof. Further, the Sn alloy-based negative electrode active materials may contain metal elements other than tin, such as iron (Fe), cobalt (Co), antimony (Sb), bismuth (Bi), lead (Pb), nickel (Ni), copper (Cu), zinc (Zn), germanium (Ge), indium (In), tin (Sn), titanium (Ti), etc.

[0031] The carbon material is not particularly limited, and examples thereof include hard carbon, soft carbon, graphite, carbon black, etc.

[0032] The shape of the active material is not particularly limited, and for example, it may be particulate. When the active material is particulate, the particle diameter D 50 of the active material may be, for example, 1 nm or more, 5 nm or more, or 10 nm or more, and may also be 500 μm or less, 100 μm or less, 5 μm or less, or 30 μm or less. Note that the particle diameter D 50This is the particle diameter (median diameter) at 50% of the integrated value in the volume-based particle size distribution determined by laser diffraction and scattering.

[0033] ≪Method for manufacturing the active material layer≫ A method for producing an active material layer according to this disclosure comprises providing an active material layer precursor containing composite active material particles described in this disclosure, and dissolving ethylene carbonate in the composite active material particles.

[0034] <Composite active material particles> For the composite active material particles used in the method for manufacturing the active material layer of this disclosure, refer to the above description regarding composite active material particles.

[0035] <Active material layer> The active material layer of this disclosure comprises first and / or second active material particles and a conductive material. The active material layer may further optionally contain at least one of a solid electrolyte and a binder.

[0036] The content of active material particles in the active material layer of this disclosure is not particularly limited, but may be 1% by mass or more, 5% by mass or more, 10% by mass or more, 15% by mass or more, or 20% by mass or more, and may be 50% by mass or less, 45% by mass or less, 40% by mass or less, 35% by mass or less, or 30% by mass or less.

[0037] For details regarding the active material particles contained in the active material layer in this disclosure, please refer to the above description of the composite active material particles in this disclosure.

[0038] In this disclosure, the thickness of the active material layer is not particularly limited, but may be, for example, 0.1 μm or more, 1.0 μm or more, 3.0 μm or more, 5.0 μm or more, or 10 μm or more, and may be 1000 μm or less, 700 μm or less, 500 μm or less, 300 μm or less, or 100 μm or less.

[0039] In this disclosure, the density of the active material layer is not particularly limited, but is 0.5 g / cm³. 3 More than 0.7g / cm3 More than 1.0g / cm 3 More than 1.5g / cm 3 Above, or 2.0 g / cm³ 3 The above is acceptable, or 15 g / cm³ 3 Below, 10g / cm 3 Below, 8g / cm 3 Below, 6g / cm 3 Below, 4g / cm 3 The following, or 3 g / cm³ 3 The following is acceptable:

[0040] In this disclosure, the solid electrolyte optionally included in the active material layer may be one known as a solid electrolyte for secondary batteries. Examples of solid electrolytes include inorganic solid electrolytes such as sulfide solid electrolytes, oxide solid electrolytes, and halide solid electrolytes, and organic polymer electrolytes such as polymer electrolytes. From the viewpoint of heat resistance, sulfide solid electrolytes and oxide solid electrolytes are particularly preferred. The solid electrolyte may be in particulate form, for example. Only one type of solid electrolyte may be used alone, or two or more types may be used in combination.

[0041] Examples of 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. The sulfide solid electrolyte may further contain at least one of O and halogen elements. Examples of halogen elements include F, Cl, Br, and I. The sulfide solid electrolyte may be made of glass (amorphous) or glass ceramics. Examples of sulfide solid electrolytes include, but are not limited to, Li2S-P2S5, LiI-Li2S-P2S5, LiI-LiBr-Li2S-P2S5, Li2S-SiS2, Li2S-GeS2, and Li2S-P2S5-GeS2.

[0042] Examples of oxide solid electrolytes include Li7La3Zr2O. 12 Li 7-x La3Zr 1-x Nb xO 12 Li 7-3x La3Zr2Al x O 12 Li 3x La 2 / 3-x TiO3, Li 1+x Al x Ti 2-x (PO4)3, Li 1+x Al x Ge 2-x (PO4)3, Li3PO4, or Li 3+x PO 4-x N x Examples include (LiPON), but are not limited to these. The oxide solid electrolyte may be amorphous or crystalline.

[0043] Examples of halogen solid electrolytes include NaBH4 and NaB 10 H 10 NaCB9H 10 NaCB 11 H 12 NaB 12 Cl 12 These are some examples, but are not limited to them.

[0044] Examples of polymer electrolytes include, but are not limited to, polyethylene oxide (PEO), polypropylene oxide (PPO), and copolymers thereof.

[0045] The content of the solid electrolyte optionally included in the active material layer of this disclosure is not particularly limited, but may be 1.0% by mass or more, 5.0% by mass or more, 10% by mass or more, 13% by mass or more, or 15% by mass or more, and may be 30% by mass or less, 20% by mass or less, 15% by mass or less, or 10% by mass or less.

[0046] In this disclosure, the binder optionally included in the active material layer may be one known as a binder used in secondary batteries. Examples of binders include styrene-butadiene rubber (SBR), carboxymethylcellulose (CMC), acrylonitrile-butadiene rubber (ABR), butadiene rubber (BR), polyvinylidene fluoride (PVDF), and polytetrafluoroethylene (PTFE). The binder may be used alone or in combination of two or more types.

[0047] The binder content optionally included in the active material layer of this disclosure is not particularly limited, but may be 0.1% by mass or more, 0.5% by mass or more, 1.0% by mass or more, 3.0% by mass or more, or 5.0% by mass or more, and may be 20% by mass or less, 15% by mass or less, 10% by mass or less, 8% by mass or less, or 5% by mass or less.

[0048] ≪Manufacturing Method for Electrode Stack Modules≫ A method for manufacturing an electrode stack module according to the present disclosure includes manufacturing an active material layer by the method according to the present disclosure.

[0049] <Electrode Laminate Module> The electrode stack module of this disclosure comprises an electrode stack containing an active material layer manufactured by the method of this disclosure, housed in an outer container or the like. The outer container or the like in this disclosure is not particularly limited.

[0050] The present disclosure will be further described with reference to the following embodiments, but the scope of the present disclosure is not limited to these embodiments. [Examples]

[0051] <Example 1> (preparation) Silicon carbide (SiC) and ethylene carbonate were prepared as active materials, and acetylene black was prepared as a conductive material. At this time, the mass ratio of silicon carbide, ethylene carbonate, and acetylene black was silicon carbide:ethylene carbonate:acetylene black = 100:8:2.

[0052] (Fabrication of conductive material-containing ethylene carbonate composites) Ethylene carbonate was heated to 60°C to melt it. Then, the ethylene carbonate was heated in a water bath at 60°C and dispersed in a homogenizer. Acetylene black was added little by little to disperse the acetylene black in the ethylene carbonate, thereby obtaining a conductive material-containing ethylene carbonate composite.

[0053] (Fabrication of composite active material particles) Silicon carbide was introduced into the rolling fluidized bed of a rolling fluid coating apparatus and allowed to flow. Using a pump, the conductive material-containing ethylene carbonate composite was sprayed into the rolling fluidized bed in an atomized form, coating the silicon carbide with the conductive material-containing ethylene carbonate composite to obtain composite active material particles.

[0054] (Fabrication of electrode stacks and measurement of expansion rate) A negative electrode active material layer containing a conductive material-containing ethylene carbonate composite and graphite in a ratio of 10:90 was fabricated, and a battery containing this negative electrode active material layer was constructed. The battery was charged from 0% to 100%, and the expansion rate of the battery in the stacking direction before and after charging was measured.

[0055] <Comparative Example 1> A battery in Comparative Example 1 was prepared in the same manner as in Example 1, except that the conductive material-containing ethylene carbonate composite was replaced with silicon carbide, and the expansion rate of the battery was measured.

[0056] <Rating> Table 1 below shows the expansion rates of the batteries in Comparative Example 1 and Example 1. Compared to the battery in Comparative Example 1, which had a negative electrode active material layer containing silicon carbide and graphite, the battery in Example 1, which had a negative electrode active material layer containing a conductive material-containing ethylene carbonate composite and graphite, showed a lower expansion rate before and after charging. It was confirmed that the expansion of the battery due to charging and discharging can be suppressed by providing a negative electrode active material layer containing a conductive material-containing ethylene carbonate composite and graphite.

[0057] [Table 1] [Explanation of Symbols]

[0058] 100 Composite active material particles 120 Conductive material-containing ethylene carbonate composite 122 Ethylene carbonate 124 Conductive materials 140 First active material particle 160 Second active material particle

Claims

1. A conductive material-containing ethylene carbonate composite comprising solid ethylene carbonate and a conductive material dispersed in the solid ethylene carbonate.

2. A composite active material particle comprising the conductive material-containing ethylene carbonate composite according to claim 1, and the first active material particle.

3. A composite active material particle according to claim 2, having a second active material particle arranged around it.

4. To provide an active material layer precursor containing the composite active material particles described in claim 2, and Dissolving ethylene carbonate in the aforementioned composite active material particles, A method for producing an active material layer, including the active material layer.

5. A method for manufacturing an electrode stack module, comprising manufacturing an active material layer by the method described in claim 4.

Images