negative electrode slurry

Abstract

This invention relates to negative electrode slurries. The main objective is to provide a negative electrode slurry for all-solid-state batteries that suppresses variations in constrained pressure. This disclosure provides a negative electrode slurry for all-solid-state batteries that solves the aforementioned problem, containing a Si-based negative electrode active material, a first dispersion medium, and a second dispersion medium, satisfying: (i) the hydrogen bonding term σH of the Hansen solubility parameter of the Si-based negative electrode active material, the first dispersion medium, and the second dispersion medium is set to σH. Si Let σH1 and σH2 be denoted as ΔσH1=σH Si -σH1, ΔσH2=σH Si When -σH2, ΔσH2 / ΔσH1 is less than 0.96; (ii) when the boiling point of the first dispersion medium is set to T1 and the boiling point of the second dispersion medium is set to T2, T2-T1≧-3℃; (iii) when the content of the first dispersion medium is set to W1 and the content of the second dispersion medium is set to W2, 0.1≦W2 / (W1+W2)≦0.25.

Description

Technical Field

[0001] This invention relates to negative electrode slurry for all-solid-state batteries. Background Technology

[0002] All-solid-state batteries are batteries with a solid electrolyte layer between the positive and negative electrode layers. Compared with liquid batteries with electrolytes containing flammable organic solvents, they have the advantage of being easier to simplify safety devices.

[0003] As a negative electrode active material used in the negative electrode layer of an all-solid-state battery, active materials containing Si (Si-based active materials) are known (Patent Document 1). Furthermore, Patent Document 2 discloses an electrode slurry for all-solid-state batteries, containing two or more solvents. The absolute value of the difference between the relative permittivity εm of the solvent with the largest volume fraction (the main solvent Sm) and the relative permittivity εn of the solvent other than the main solvent Sm (the secondary solvent Sn) is |εm-εn|, both being 1.31 or greater, where n is a natural number maximizing the number of secondary solvent types.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2020-004685

[0007] Patent Document 2: Japanese Patent Application Publication No. 2015-082362 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] Si-based active materials have the advantage of high theoretical capacity per unit volume, but on the other hand, they exhibit large volume changes due to charging and discharging. When using Si-based active materials with such large volume changes as negative electrode active materials, the variation in confinement pressure in all-solid-state batteries may increase. Large variations in confinement pressure can potentially lead to short circuits caused by the peeling or slippage of the negative electrode active material layer.

[0010] This disclosure was made in view of the above-mentioned actual situation, and its main purpose is to provide a negative electrode slurry for an all-solid-state battery in which variations in the applied constraint pressure are suppressed.

[0011] Methods for solving problems

[0012] To address the aforementioned issues, this disclosure provides a negative electrode slurry for use in all-solid-state batteries, comprising a Si-based negative electrode active material, a first dispersion medium, and a second dispersion medium, satisfying: (i) the hydrogen bond term (σH) of the Hansen solubility parameters of the Si-based negative electrode active material, the first dispersion medium, and the second dispersion medium is respectively set to σH.Si Let σH1 and σH2 be denoted as ΔσH1=σH Si -σH1, ΔσH2=σH Si In the case of -σH2, the ratio of ΔσH2 to ΔσH1 (ΔσH2 / ΔσH1) is 0.96 or less; (ii) when the boiling point of the first dispersion medium is set to T1 and the boiling point of the second dispersion medium is set to T2, T2-T1 ≥ -3℃; and (iii) when the content of the first dispersion medium is set to W1 and the content of the second dispersion medium is set to W2, 0.1 ≤ W2 / (W1+W2) ≤ 0.25.

[0013] According to this disclosure, the negative electrode slurry satisfies (i), (ii) and (iii), thereby enabling the provision of a negative electrode slurry for an all-solid-state battery in which variations in the constraint pressure are suppressed.

[0014] Invention Effects

[0015] In this disclosure, the effect of providing a negative electrode slurry for an all-solid-state battery that suppresses variations in the applied constraint pressure is achieved. Attached Figure Description

[0016] Figure 1 This is a schematic diagram illustrating the state of each component in the membrane during the negative electrode active material layer formation process using the negative electrode slurry of this disclosure.

[0017] Figure 2 This is a schematic diagram illustrating the state of each component in the membrane during the negative electrode active material layer formation process using conventional negative electrode slurry.

[0018] Figure 3 A flowchart illustrating an example of a method for manufacturing the negative electrode slurry in this disclosure.

[0019] Figure 4 A schematic cross-sectional view is shown to illustrate an example of an all-solid-state battery using the negative electrode slurry of this disclosure.

[0020] Figure 5 This is a diagram illustrating the method for measuring the variation of constraint pressure in the embodiments and comparative examples.

[0021] Explanation of reference numerals in the attached figures

[0022] 1. Negative current collector

[0023] 2. Negative electrode active material layer

[0024] 3. Solid electrolyte layer

[0025] 4 Positive electrode active material layer

[0026] 5 Positive current collector

[0027] 10 All-Solid-State Batteries Detailed Implementation

[0028] The negative electrode slurry in this disclosure will now be described in detail.

[0029] The negative electrode slurry disclosed herein contains a Si-based negative electrode active material, a first dispersion medium, and a second dispersion medium, satisfying: (i) when the hydrogen bond term (σH) of the Hansen solubility parameter of the above-mentioned Si-based negative electrode active material, the above-mentioned first dispersion medium, and the above-mentioned second dispersion medium is respectively set to σH Si Let σH1 and σH2 be denoted as ΔσH1=σH Si -σH1, ΔσH2=σH Si In the case of -σH2, the ratio of ΔσH2 to ΔσH1 (ΔσH2 / ΔσH1) is 0.96 or less; (ii) when the boiling point of the first dispersion medium is set to T1 and the boiling point of the second dispersion medium is set to T2, T2-T1 ≥ -3℃; and (iii) when the content of the first dispersion medium is set to W1 and the content of the second dispersion medium is set to W2, 0.1 ≤ W2 / (W1+W2) ≤ 0.25.

[0030] According to this disclosure, the negative electrode slurry satisfies (i), (ii) and (iii), thereby enabling it to be a negative electrode slurry for an all-solid-state battery in which variations in the applied constraint pressure are suppressed.

[0031] Figure 2 This is a schematic diagram illustrating the state of each component in the membrane during the negative electrode active material layer formation process using conventional negative electrode slurry. Figure 2 In this context, Si represents the Si-based negative electrode active material, SE represents the solid electrolyte, C represents the conductive material, and D represents the dispersion medium. Regarding the conventional negative electrode slurry 12, after being coated onto the negative electrode current collector 1 ( Figure 2 (a)), Si-based negative electrode active materials accumulate over time during drying ( Figure 2 (b)). Therefore, the film density decreases after drying. Figure 2 (c)). It is believed that the aggregation of Si-based active materials in such slurry, leading to a decrease in film density and uneven reaction after drying, is the main reason for the increased variation in confinement pressure in all-solid-state batteries.

[0032] In contrast, the inventors have discovered that if the negative electrode slurry satisfies (i), (ii) and (iii), the aggregation of Si-based active materials can be suppressed, and the film density after drying can be increased. Figure 1This is a schematic diagram illustrating the state of each component in the membrane during the negative electrode active material layer formation process using the negative electrode slurry of this disclosure. In addition to the first dispersion medium D1, the negative electrode slurry 11 of this disclosure also includes, within a defined range, a second dispersion medium D2 with high affinity for the Si-based active material, thereby creating a second dispersion medium D2 near the surface of the Si-based active material. Figure 1 (a) suggests that this improves the dispersibility of the Si-based active material. Furthermore, the boiling point of the second dispersion medium D2 is the same as or higher than that of the first dispersion medium D1, suggesting that this can improve the slippage of the Si-based active material particles during the final stage of negative electrode drying. Figure 1 (b) can increase the film density after drying. Figure 1 (c)).

[0033] Therefore, by using the negative electrode slurry of this disclosure, the film thickness deformation caused by drying (ΔT1=T0-T1) can be reduced compared to the film thickness deformation caused by conventional drying. Figure 2 As ΔT3 = T0 - T2 increases, the film thickness deformation caused by pressing (ΔT2 = T1 - Tp) is greater than that caused by previous pressing. Figure 2 The ΔT4 (T2 - Tp) is reduced. Therefore, it is possible to reduce the plastic deformation of the solid electrolyte and suppress particle disintegration (collapse), thereby ensuring a percolation structure and homogenizing the expansion and contraction of Si particles within the electrode caused by charging and discharging. In this disclosure, the hydrogen bonding term (σH) of the Hansen solubility parameter is considered as an indicator of affinity.

[0034] 1. First dispersion medium and second dispersion medium

[0035] The negative electrode slurry in this disclosure includes a first dispersion medium and a second dispersion medium within a specified range. The hydrogen bonding term (σH) of the Hansen solubility parameter (HSP) of the Si-based negative electrode active material, the first dispersion medium, and the second dispersion medium is set as σH, respectively. Si Let σH1 and σH2 be denoted as ΔσH1=σH Si -σH1, ΔσH2=σH Si In the case of -σH2, the ratio of ΔσH2 to ΔσH1 (ΔσH2 / ΔσH1) is 0.96 or less. That is, in this disclosure, the second dispersion medium is a dispersion medium with high affinity for Si-based active materials compared to the first dispersion medium.

[0036] HSP is known as a parameter used to evaluate the affinity between materials. HSP consists of three parameters: σD (energy of intermolecular dispersion forces), σP (energy of intermolecular dipole interactions), and σH (energy of intermolecular hydrogen bonds) (unit: MPa). 0.5The composition is as follows. In negative electrode slurry materials, σD varies little between materials, and σP is limited. Therefore, this invention focuses on σH. The hydrogen bond term (σH) of the Hansen solubility parameter can be obtained, for example, from Hansen Solubility Parameters: Auser's handbook, Second Edition. Boca Raton, Fla: CRC Press. (Hansen, Charles (2007)).

[0037] ΔσH2 / ΔσH1 can be less than 0.91 or less than 0.85. On the other hand, ΔσH2 / ΔσH1 can be greater than 0.13 or greater than 0.17.

[0038] In this disclosure, the first and second dispersion media satisfy the condition T2-T1 ≥ -3℃, provided that the boiling point of the first dispersion media is set as T1 and the boiling point of the second dispersion media is set as T2. That is, in this disclosure, the boiling point of the second dispersion media is the same as or higher than the boiling point of the first dispersion media. T2-T1 can be above 0℃ or above 3℃.

[0039] Furthermore, in this disclosure, when the content of the first dispersion medium is set to W1 and the content of the second dispersion medium is set to W2, the condition 0.1 ≤ W2 / (W1+W2) ≤ 0.25 is satisfied. W2 / (W1+W2) can be 0.15 or more. In addition, W2 / (W1+W2) can be 0.2 or less.

[0040] In addition, the content of Si-based negative electrode active material in the slurry is set as W. Si In the case of W1 relative to W Si The ratio (W1 / W) Si For example, if it is 1.5 or higher, it can be 1.6 or higher. On the other hand, if it is 1.8 or lower, it can be 1.7 or lower. Additionally, W2 is relative to W. Si ratio (W2 / W) Si For example, if it is above 0.2, it can be above 0.3. On the other hand, if it is below 0.5, it can be below 0.4.

[0041] In addition, the content of the dispersion medium (W1+W2) in the slurry relative to W Si The ratio ((W1+W2) / W) Si There are no special restrictions; for example, it can be 1 or more but less than 3, or it can be 2.

[0042] As a combination of a first dispersion medium and a second dispersion medium that satisfies (i), (ii), and (iii) above, when the first dispersion medium is mesitylene, the second dispersion medium may include tetrahydronaphthalene, diisobutyl ketone (DIBK), butyl butyrate, methyl benzoate, dimethylacetamide, benzyl alcohol, etc. When the first dispersion medium is DIBK, the second dispersion medium may include butyl butyrate, methyl benzoate, dimethylacetamide, benzyl alcohol, etc. When the first dispersion medium is butyl butyrate, the second dispersion medium may include dimethylacetamide, benzyl alcohol, etc.

[0043] 2. Si-based negative electrode active material

[0044] The negative electrode slurry disclosed herein contains a Si-based active material as the negative electrode active material. The Si-based active material is preferably an active material capable of alloying with Li. Examples of Si-based active materials include elemental Si, Si alloys, and Si oxides. The Si alloy preferably contains Si as a main component. The proportion of Si in the Si alloy can be, for example, 50 mol% or more, 70 mol% or more, or 90 mol% or more.

[0045] The average particle size (D) of Si-based active materials 50 For example, the particle size can be 10 nm or larger, or even 100 nm or larger. On the other hand, the average particle size (D) of Si-based active materials... 50 For example, it can be below 50 μm, or below 20 μm. Average particle size (D) 50 For example, it can be calculated using a laser diffraction particle size analyzer or a scanning electron microscope (SEM).

[0046] 3. Negative electrode slurry

[0047] The negative electrode slurry in this disclosure may include binders, solid electrolytes, and conductive materials as needed.

[0048] Examples of adhesives include fluorinated adhesives such as polyvinylidene fluoride (PVdF) and rubber-based adhesives such as butene rubber (BR) and styrene-butadiene rubber (SBR). The proportion of the adhesive in the solids component of the slurry is, for example, 1% by weight or more and 10% by weight or less.

[0049] Examples of solid electrolytes include inorganic solid electrolytes such as sulfide solid electrolytes, oxide solid electrolytes, nitride solid electrolytes, and halide solid electrolytes, with sulfide solid electrolytes being preferred. Examples of sulfide solid electrolytes include solid electrolytes containing Li, X (where X is at least one of P, Si, Ge, Sn, B, Al, Ga, and In), and S. Furthermore, sulfide solid electrolytes may further contain at least one of O and a halogen element. The proportion of solid electrolyte in the solid component of the slurry is, for example, 1% by weight or more and 50% by weight or less.

[0050] Examples of conductive materials include carbon materials such as carbon nanotubes and carbon nanofibers, such as VGCF (vapor-phase carbon fiber). The proportion of conductive material in the solid component of the slurry is, for example, more than 1% by weight and less than 20% by weight.

[0051] There are no particular limitations on the manufacturing method of the negative electrode slurry in this disclosure; for example, it can be as follows: Figure 3 The process is as shown. First, a first dispersion medium and a binder are added to a first container and mixed. Then, a conductive material is added and mixed. Next, a second dispersion medium and a Si-based active material are added to a second container (not the first container) and mixed. The mixture of the second dispersion medium and the Si-based active material from the second container is then added to the first container and mixed. Finally, a solid electrolyte is added and mixed to obtain a negative electrode slurry. Thus, by pre-mixing the second dispersion medium and the Si-based active material, the affinity of the second dispersion medium for the Si-based active material can be further improved.

[0052] The negative electrode slurry in this disclosure is a negative electrode slurry used to form the negative electrode active material layer in an all-solid-state battery. Figure 4 A schematic cross-sectional view is shown to illustrate an example of an all-solid-state battery using the negative electrode slurry of this disclosure. Figure 4 The all-solid-state battery 10 shown has, in sequence, a negative electrode current collector 1, a negative electrode active material layer 2, a solid electrolyte layer 3, a positive electrode active material layer 4, and a positive electrode current collector 5. Figure 4 The negative electrode active material layer 2 shown contains a Si-based active material as the negative electrode active material. For example, a method for forming the negative electrode active material layer can be described as coating the aforementioned negative electrode slurry onto a negative electrode current collector and then drying it. There are no particular limitations on the slurry coating method; any known coating method can be used.

[0053] All-solid-state batteries can be single cells or stacked cells. Stacked cells can be unipolar stacked cells (parallel-connected stacked cells) or bipolar stacked cells (series-connected stacked cells). Examples of battery shapes include coin-shaped, laminated, cylindrical, and square.

[0054] It should be noted that this disclosure is not limited to the embodiments described above. The embodiments described above are illustrative examples, and embodiments having substantially the same structure and achieving the same effect as those described in the claims of this disclosure are all included within the technical scope of this disclosure.

[0055] [Example]

[0056] (Comparative Example 1-1)

[0057] [Manufacturing of negative electrode slurry]

[0058] A dispersion medium (mesotriene) and a binder (SBR) were added to a container and mixed. Then, a conductive material (VGCF) was added and mixed. Next, a Si-based negative electrode active material (elemental Si) was added and mixed. Finally, a sulfide solid electrolyte was added and mixed. This yielded the negative electrode slurry with the composition shown in Table 1.

[0059] [Evaluation of battery cell fabrication]

[0060] The obtained negative electrode slurry was coated onto the negative electrode current collector (Ni foil, 24 μm thick) and dried at 210 °C to form a negative electrode active material layer.

[0061] The positive electrode active material (LiNi) 1 / 3 Co 1 / 3 Mn 1 / 3 A paste-like positive electrode composition is prepared by mixing O2, a dispersion medium (butyl butyrate), a binder (5 wt% butyl butyrate solution of PVdF-based binder), a sulfide solid electrolyte (Li2S-P2S5 glass-ceramic containing LiBr and LiI), and a conductive material (VGCF). This composition is then coated onto a 10 μm thick aluminum foil (positive electrode current collector) and dried to form the positive electrode active material layer.

[0062] A solid electrolyte composition is prepared by mixing a dispersion medium (heptane), a binder (a 5 wt% heptane solution of butadiene rubber), and a sulfide solid electrolyte (a Li2S-P2S5 glass-ceramic containing LiBr and LiI). This composition is then coated onto an aluminum foil (substrate) and dried to form a solid electrolyte layer.

[0063] The solid electrolyte layer is laminated onto the positive electrode active material layer in a manner that brings the solid electrolyte layer to the positive electrode active material layer, and then pressed. Next, the substrate (aluminum foil) of the solid electrolyte layer is peeled off, and the negative electrode active material layer is laminated in a manner that brings the solid electrolyte layer to the negative electrode active material layer, and then pressed. This completes the fabrication process. Figure 5(a) shows the evaluation battery cell. It is noted that the electrode area is set to 1 cm². 2 The thickness of the positive electrode active material layer (density 3.7 g / cc) is 70.0 μm, the thickness of the solid electrolyte layer is 15.0 μm, and the thickness of the negative electrode active material layer (density 1.8 g / cc) is 45.3 μm.

[0064] [Evaluation of Constraint Pressure Variation]

[0065] exist Figure 5 (b) shows a fixture on which four of the aforementioned evaluation battery cells are installed. The variation in constraint pressure is measured using a pressure measuring unit, and the effect of suppressing the variation in constraint pressure is evaluated. Specifically, the variation in constraint pressure is normalized according to the following formula for evaluation.

[0066] (Constraint pressure at the end of charging (MPa) - Constraint pressure at the start of charging (MPa)) / (Number of battery cells × Capacity at the end of charging (mAh))

[0067] Values ​​below 0.29 MPa / mAh obtained from the above formula are rated as ○, and values ​​above 0.29 MPa / mAh are rated as ×. The results are shown in Table 1. Additionally, the negative electrode slurry was coated onto the negative electrode current collector, dried, and the electrode density was calculated. The results are shown in Table 1.

[0068] (Examples 1-1 to 1-6, Comparative Examples 1-2 to 1-3)

[0069] Using a first dispersion medium (mesotriene) and a second dispersion medium as shown in Table 1, the mixture was prepared at the weight ratio shown in Table 1. Otherwise, the process was the same as in Comparative Example 1-1 to manufacture a negative electrode slurry, produce an evaluation battery cell, and conduct an evaluation. Furthermore, compared to the case where the first dispersion medium was used alone, cases where the drying time was delayed by more than 20% were evaluated as △, and cases where it was less than 20% were evaluated as ○.

[0070] The results are shown in Table 1.

[0071] [Table 1]

[0072]

[0073] (Comparative Example 2-1)

[0074] Using diisobutyl ketone (DIBK) as the dispersion medium, the mixture was prepared at the weight ratios shown in Table 2. Otherwise, the same procedure as in Comparative Example 1-1 was followed to prepare the negative electrode slurry, fabricate evaluation battery cells, and conduct evaluations. The results are shown in Table 2.

[0075] (Examples 2-1 to 2-4, Comparative Examples 2-2 to 2-5)

[0076] Using the first dispersion medium (DIBK) and the second dispersion medium shown in Table 2 as dispersion media, the mixture was prepared at the weight ratio shown in Table 2. Otherwise, the same procedure as in Comparative Example 1-1 was followed to prepare the negative electrode slurry, fabricate the evaluation battery cell, and conduct the evaluation. The results are shown in Table 2.

[0077] [Table 2]

[0078]

[0079] (Comparative Example 3-1)

[0080] Butyl butyrate was used as the dispersion medium, and the mixture was prepared in the weight ratios shown in Table 3. Otherwise, the same procedure as in Comparative Example 1-1 was followed to prepare the negative electrode slurry, and evaluation battery cells were fabricated and evaluated. The results are shown in Table 3.

[0081] (Examples 3-1 to 3-2, Comparative Examples 3-2 to 3-7)

[0082] Using a first dispersion medium (butyl butyrate) and a second dispersion medium as shown in Table 3, the mixture was prepared at the weight ratio shown in Table 3. Otherwise, the same procedure as in Comparative Example 1-1 was followed to prepare a negative electrode slurry, fabricate an evaluation battery cell, and conduct an evaluation. The results are shown in Table 3.

[0083] [Table 3]

[0084]

[0085] (Comparative Example 4-1)

[0086] Mestriylbenzene was used as the dispersion medium, and the mixture was prepared in the weight ratios shown in Table 4. Otherwise, the same procedure as in Comparative Example 1-1 was followed to prepare the negative electrode slurry, fabricate evaluation battery cells, and conduct evaluations. The results are shown in Table 4.

[0087] (Examples 4-1 to 4-3, Comparative Examples 4-2 to 4-3)

[0088] Using a first dispersion medium (trimethylbenzene) and a second dispersion medium (tetrahydronaphthalene) as dispersion media, the mixtures were prepared in the weight ratios shown in Table 4. Otherwise, the process was the same as in Comparative Example 1-1 to manufacture the negative electrode slurry, produce evaluation battery cells, and conduct evaluations. The results are shown in Table 4. It should be noted that Example 4-1 is identical to Example 1-1.

[0089] (Example 4-4)

[0090] A first dispersion medium (mesotriene) and a binder (SBR) were added to a first container and mixed. Then, a conductive material (VGCF) was added and kneaded. In a separate second container (not the first container), a second dispersion medium (tetrahydronaphthalene) and a Si-based active material (elemental Si) were mixed. The mixture of the second dispersion medium and the Si-based active material from the second container was added to the first container. Then, a sulfide solid electrolyte was added and mixed. Thus, a negative electrode slurry with the composition shown in Table 4 was obtained. In addition to using the obtained negative electrode slurry, evaluation battery cells were fabricated in the same manner as in Comparative Example 1-1 and evaluated. The results are shown in Table 4.

[0091] [Table 4]

[0092]

[0093] The results in Tables 1-4 confirm that, when using the negative electrode slurry of this disclosure, the electrode density after drying can be increased, and an all-solid-state battery in which confinement pressure fluctuations are suppressed can be obtained. Furthermore, in Examples 4-4, using a negative electrode slurry pre-mixed with a second dispersion medium and Si, it was confirmed that confinement pressure fluctuations were particularly suppressed.

Claims

1. Negative electrode slurry, which is the negative electrode slurry used in all-solid-state batteries. It contains Si-based negative electrode active material, a first dispersion medium, and a second dispersion medium. satisfy: (i) The hydrogen bonding term σH of the Hansen solubility parameter of the Si-based negative electrode active material, the first dispersion medium, and the second dispersion medium is set to σH respectively. Si Let σH1 and σH2 be denoted as ΔσH1=σH Si -σH1, ΔσH2=σH Si In the case of -σH2, The ratio of ΔσH2 to ΔσH1, ΔσH2 / ΔσH1, is less than 0.

96. (ii) When the boiling point of the first dispersion medium is set to T1 and the boiling point of the second dispersion medium is set to T2, T2-T1≥-3℃, (iii) When the content of the first dispersion medium is set to W1 and the content of the second dispersion medium is set to W2, 0.1≤W2 / (W1+W2)≤0.25, and (iv) The first dispersion medium is mesitylene, diisobutyl ketone, or butyl butyrate, and when the first dispersion medium is mesitylene, the second dispersion medium is at least one of tetrahydronaphthalene, diisobutyl ketone, methyl benzoate, dimethylacetamide, and benzyl alcohol; when the first dispersion medium is diisobutyl ketone, the second dispersion medium is at least one of butyl butyrate, methyl benzoate, dimethylacetamide, and benzyl alcohol; when the first dispersion medium is butyl butyrate, the second dispersion medium is at least one of dimethylacetamide and benzyl alcohol.

2. The negative electrode slurry according to claim 1, wherein, The first dispersion medium is mesitylene, and the second dispersion medium is at least one of tetrahydronaphthalene, diisobutyl ketone, methyl benzoate, dimethylacetamide, and benzyl alcohol.

3. The negative electrode slurry according to claim 1, wherein, The first dispersion medium is diisobutyl ketone, and the second dispersion medium is at least one of butyl butyrate, methyl benzoate, dimethylacetamide, and benzyl alcohol.

4. The negative electrode slurry according to claim 1, wherein, The first dispersion medium is butyl butyrate, and the second dispersion medium is at least one of dimethylacetamide and benzyl alcohol.

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