Negative electrode for battery and battery

Abstract

This negative electrode for a battery is provided with: a first negative electrode active material layer that contains first graphite having an aspect ratio of 2 to 5 and second graphite having an aspect ratio of 1 to 1.4, and that has a peak intensity ratio as determined by XRD measurement of 0.03 or more; and a current collector.

Description

Technical Field

[0001] The present invention relates to a negative electrode for a battery and a battery. Background Art

[0002] In recent years, in order to achieve high energy density and low cost, the weight per unit area of the active material in the electrodes of secondary batteries such as lithium-ion batteries has a tendency to increase.

[0003] In such electrodes, the charge-discharge capacity at high rates is significantly reduced. In response to this, the following attempts have been reported. In order to increase the charge-discharge capacity of a lithium-ion battery, in the negative electrode, the graphite serving as the negative electrode active material is oriented (for example, refer to Japanese Unexamined Patent Application Publication No. 2022-167890). Summary of the Invention

[0004] However, the above orientation of graphite is difficult to maintain after the pressing process in forming the negative electrode.

[0005] A problem to be solved by an embodiment of the present invention is to provide a negative electrode for a battery with low resistance and a battery including the negative electrode for a battery.

[0006] In the solution for solving the above problem, the following modes are included.

[0007] <1> A negative electrode for a battery, comprising: a first negative electrode active material layer containing a first graphite having an aspect ratio of 2 to 5 and a second graphite having an aspect ratio of 1 to 1.4, and a peak intensity ratio I 110 / I 002 determined by X-ray diffraction (XRD) measurement is 0.03 or more; and a current collector.

[0008] <2> The negative electrode for a battery according to <1>, wherein in the first negative electrode active material layer, the mass ratio of the second graphite to the first graphite is 30 / 70 to 70 / 30.

[0009] <3> The negative electrode for a battery according to <1> or <2>, further comprising a second negative electrode active material layer between the first negative electrode active material layer and the current collector, the second negative electrode active material layer containing the second graphite and not containing the first graphite.

[0010] <4> The negative electrode for a battery according to any one of <1> to <3> has the first negative electrode active material layer as the outermost layer.

[0011] <5> A battery including the negative electrode for a battery according to any one of <1> to <4>.

[0012] According to the present invention, a negative electrode for a battery with low resistance and a battery including the negative electrode for a battery are provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Hereinafter, with reference to the drawings, the features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described. In the drawings, the same reference numerals denote the same elements, and:

[0014] Figure 1 is a schematic cross-sectional view showing an example of the structure of the negative electrode for a battery of the present invention.

[0015] Figure 2 is a schematic cross-sectional view showing another example of the structure of the negative electrode for a battery of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described. The description is an illustration of the embodiments and does not limit the scope of the present invention.

[0017] In this specification, a numerical range shown using "to" represents a range that includes the numerical values described before and after "to" as the minimum value and the maximum value, respectively.

[0018] In the numerical ranges described stepwise in this specification, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of another stepwise described numerical range. And, in the numerical ranges described in this specification, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples.

[0019] In this specification, the term "process" includes not only independent processes but also, even in cases where it cannot be clearly distinguished from other processes, as long as the intended purpose of the process can be achieved, it is included in this term.

[0020] In this specification, when describing an embodiment with reference to the drawings, the structure of the embodiment is not limited to the structure shown in the drawings. Also, the sizes of the components in each figure are conceptual, and the relative size relationships between the components are not limited thereto.

[0021] In this specification, each component may include a plurality of corresponding substances. When referring to the amounts of the components in the composition in this embodiment, in cases where there are a plurality of substances corresponding to each component in the composition, unless otherwise specified, it represents the total amount of the plurality of substances present in the composition.

[0022] In this specification, the term "aspect ratio" refers to the ratio of the long axis to the short axis (long axis / short axis) in graphite particles, and an aspect ratio of 1 represents a perfect circle.

[0023] Specifically, the "aspect ratio" means, in the case of the first graphite, the ratio b / c when the length of the short axis of the rectangular parallelepiped circumscribing the graphite particles (including secondary particles) is b and the thickness is c. And, in the case of the second graphite, it means the ratio a / b when the length of the long axis of the cube or rectangular parallelepiped circumscribing the graphite particles (including secondary particles) is a and the length of the short axis is b.

[0024] In this specification, the term "collapse" means that the graphite particles oriented in the vertical direction lose their oriented state.

[0025] In this specification, the "particle size" represents the volume-averaged median particle size D50.

[0026] <Negative electrode for battery>

[0027] The negative electrode for battery of the present invention (hereinafter, also simply referred to as "negative electrode".) includes: a first negative electrode active material layer containing a first graphite having an aspect ratio of 2 to 5 and a second graphite having an aspect ratio of 1 to 1.4, and the peak intensity ratio (I 110 / I 002 ) is 0.03 or more; and a current collector.

[0028] With the above structure, even after the pressing process is performed during the manufacturing of the electrode, the orientation of the graphite having a high aspect ratio (graphite having a shape such as a flake shape, a flat plate shape, or an elliptical shape) in the negative electrode can be maintained. Thus, a negative electrode for battery with a low resistance is provided. As a result, a battery with a high energy density can be obtained.

[0029] The reason for obtaining the above effect is presumably as follows.

[0030] It is considered that this is because the graphite with a high aspect ratio oriented in the vertical direction in the electrode (especially the surface layer of the electrode) is likely to expand or contract in the in-plane direction during charge and discharge, so it is easy to ensure the invasion path of ions into the electrode and becomes a low resistance.

[0031] Hereinafter, the structure of the negative electrode will be described.

[0032] Figure 1 is a schematic cross-sectional view showing an example of the structure of a negative electrode for battery which is an embodiment of the negative electrode for battery of the present invention. As Figure 1 shown, the negative electrode for battery 100 includes a first negative electrode active material layer 10 and a current collector 20. The first negative electrode active material layer 10 includes a first graphite 1 with a high aspect ratio and a second graphite 2 with a low aspect ratio.

[0033] The first negative electrode active material layer

[0034] The first negative electrode active material layer contains first graphite and second graphite. The aspect ratio of the first graphite is 2 to 5. The aspect ratio of the second graphite is 1 to 1.4. Since the aspect ratio of the first graphite is 2 to 5, when a magnetic field is applied to the first negative electrode active material layer, the first graphite is likely to be oriented in the vertical direction of the negative electrode. Also, since the aspect ratio of the second graphite is 1 to 1.4 and it is included in the first negative electrode active material layer together with the first graphite, it is easy to suppress the collapse of the first graphite that is oriented by the magnetic field during pressing. Therefore, even after the pressing process, the orientation of the first graphite is maintained. For example, when the aspect ratio of the second graphite is 1, the second graphite is spherical, and the second graphite does not collapse and suppresses the collapse of the first graphite.

[0035] The first graphite and the second graphite can be natural graphite or artificial graphite. The natural graphite can be flake graphite or earthy graphite.

[0036] Regarding the shapes of the first graphite and the second graphite, as long as the above-mentioned aspect ratios are satisfied, there is no particular limitation. Regarding the shape of the first graphite, it includes flat plate shapes (for example, flake shape, elliptical shape), etc. Also, regarding the shape of the second graphite, it includes spherical shapes (for example, regular spherical shape, elliptical spherical shape), etc.

[0037] The particle diameters of the first graphite and the second graphite can be 0.1 μm to 100 μm.

[0038] The specific surface areas of the first graphite and the second graphite can be 0.1 m 2 / g to 1,500 m 2 / g.

[0039] In the first negative electrode active material layer, the mass ratio of the second graphite to the first graphite (mass% of the second graphite / mass% of the first graphite) is preferably 30 / 70 to 70 / 30. Since the mass ratio of the second graphite to the first graphite (mass% of the second graphite / mass% of the first graphite) is 30 / 70 to 70 / 30, it is easier to suppress the collapse of the first graphite in the first negative electrode active material layer and easier to maintain the orientation. Therefore, when constructing a battery (battery cell), the capture and release properties of ions (for example, lithium ions) are increased, so the battery cell resistance is reduced and the battery is likely to have a high capacity.

[0040] The first negative electrode active material layer may further contain a binder and a conductive material (not shown in Figure 1 ).

[0041] Examples of the binder include polyvinylidene fluoride (PVDF) / NMP-based, styrene-butadiene rubber (SBR) / water-based, polytetrafluoroethylene (PTFE) / water-based binders, etc. The binder may contain carboxymethyl cellulose (CMC) as a thickener.

[0042] The content of the binder can be 0.1% by mass to 5% by mass relative to the total amount of the first graphite and the second graphite.

[0043] As the conductive agent, carbon materials such as acetylene black, Ketjen black, vapor-grown carbon fiber (VGCF (registered trademark)), carbon nanotube (CNT), etc. can be mentioned.

[0044] The content of the conductive agent can be 0.1% by mass to 5% by mass relative to the total amount of the first graphite and the second graphite.

[0045] Current collector

[0046] As the current collector, a publicly known current collector can be used. For example, it can be appropriately selected from components composed of metal parts such as Cu, Al, Fe, Co, Ni, Cr, Ni-plated steel, stainless steel, etc. As the negative electrode current collector, the one composed of Cu is preferred.

[0047] The thickness of the current collector is not particularly limited. For example, it can be 0.1 μm to 1,000 μm.

[0048] The negative electrode for a battery of the present invention is obtained by providing a first negative electrode active material layer on a current collector. In one embodiment of the negative electrode for a battery of the present invention, the first negative electrode active material layer is provided on the current collector. More specifically, the negative electrode for a battery of the present invention can be manufactured, for example, by coating a slurry for forming a first negative electrode active material layer containing the first graphite and the second graphite on the current collector, applying a magnetic field, drying, and pressing.

[0049] The slurry can be prepared by kneading the first graphite and the second graphite, a binder, a conductive agent as needed, a thickener, etc.

[0050] The kneading can be carried out by a publicly known method. For example, a planetary mixer, a sand mill, a ball mill, a planetary mill, a roll mill, an extruder, etc. can be used.

[0051] The coating can be carried out by a publicly known method. For example, it can be carried out by a slit die method or a doctor roll method, etc.

[0052] The application of the magnetic field can be carried out by a publicly known method. For example, a magnetization device can be used. By applying a magnetic field to the slurry, the first graphite in the first negative electrode active material layer can be oriented.

[0053] When applying the magnetic field, the intensity of the magnetic field is not particularly limited as long as the first graphite in the first negative electrode active material layer is oriented. For example, it can be 0.5 T or more.

[0054] When a magnetic field is applied, the direction of the magnetic field only needs to be in the first graphite orientation in the first negative electrode active material layer, and there is no particular limitation. However, it is preferable to apply the magnetic field in a direction perpendicular to the surface of the negative electrode, because this will make the orientation of the first graphite a way suitable for increasing the capture and release of lithium ions. Thus, the cell resistance is also easily reduced, and the lithium ion battery is also easily made to have a high capacity.

[0055] Moreover, drying can be carried out by a known method. For example, it can be carried out by natural drying, reduced-pressure drying, or heat drying. The drying temperature can be, for example, from 80°C to 135°C.

[0056] Moreover, pressing can be carried out by a known method. For example, it can be carried out by a roll press, a cold isostatic press (CIP), etc. For example, pressing can be carried out so that the electrode density becomes 1.2 g / cm 3 .

[0057] The peak intensity ratio (I 110 / I 002 ) determined by XRD measurement of the first negative electrode active material layer of the negative electrode for a battery of the present invention is 0.03 or more. Referring to the Inorganic Crystal Structure Database (ICSD), the peak intensity ratio (I 110 / I 002 ) of the randomly oriented graphite powder is 0.014. Therefore, when the peak intensity ratio (I 110 / I 002 ) is greater than 0.014, the first graphite is oriented in the in-plane direction of the graphene layer structure. Therefore, when the peak intensity ratio (I 110 / I 002 ) is 0.03 or more, in the battery, the capture and release of ions (for example, lithium ions) are increased, the cell resistance is reduced, and the battery is also easily made to have a high capacity.

[0058] XRD measurement is carried out using an XRD measurement device . The peak intensity ratio (I 110 / I 002 ) is obtained based on the diffraction peak intensity I 002 attributed to the plane index (002) (the direction perpendicular to the plane of the graphene structure) near 2θ = 26.3° obtained by XRD measurement and the diffraction peak intensity I 110 attributed to the plane index (110) (the in-plane direction of the graphene structure) near 2θ = 77.7°.

[0059] The negative electrode for a battery of the present invention is also preferably in the following manner, and a second negative electrode active material layer is further provided between the first negative electrode active material layer and the current collector, and the second negative electrode active material layer contains the second graphite and does not contain the first graphite.

[0060] Figure 2 FIG. is a schematic cross-sectional view showing an example of the structure of a negative electrode for a battery according to another embodiment of the negative electrode for a battery of the present invention. As Figure 2 shown, the negative electrode 100 for a battery has a second negative electrode active material layer 30 between the first negative electrode active material layer 10 and the current collector 20. By further providing the second negative electrode active material layer 30, the diffusibility of ions (for example, lithium ions) is more easily improved as compared with the case where the negative electrode is composed of only the second negative electrode active material layer. Figure 2 The negative electrode for a battery can be manufactured by providing a second negative electrode active material layer on the current collector and further providing a first negative electrode active material layer on the second negative electrode active material layer. Among them, for the same reason as described above, it is particularly preferably in the manner of having the first negative electrode active material layer, the second negative electrode active material layer, and the current collector in this order as the outermost layer.

[0061] Second negative electrode active material layer

[0062] The second negative electrode active material layer preferably contains the second graphite as the negative electrode active material and does not contain the first graphite, and more preferably contains only the second graphite.

[0063] In addition to the second graphite, the second negative electrode active material layer may further contain a binder and a conductive agent ( Figure 2 not shown in the figure).

[0064] As the binder, the same binder as the binder exemplified in the first negative electrode active material layer can be used. The content of the binder can be the same as the content exemplified in the first negative electrode active material layer.

[0065] As the conductive agent, the same conductive agent as the conductive agent exemplified in the first negative electrode active material layer can be used. The content of the conductive agent can be the same as the content exemplified in the first negative electrode active material layer.

[0066] Battery

[0067] The battery of the present invention includes the negative electrode for a battery. The battery of the present invention is preferably in a stacked structure in which the negative electrode and the positive electrode are stacked with an electrolyte layer interposed therebetween. The battery of the present invention is preferably a secondary battery, and more preferably a lithium ion secondary battery.

[0068] Positive electrode

[0069] The positive electrode includes a positive electrode active material layer and a current collector.

[0070] The positive electrode active material layer preferably contains a positive electrode active material, a conductive agent, and a binder.

[0071] Examples of the positive electrode active material include layered, olivine-type, and spinel-type compounds. For example, lithium composite oxides can be mentioned. Examples of the lithium composite oxide include lithium cobalt oxide, lithium nickel oxide, lithium manganate, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 and the like. Examples of the layered lithium composite oxide include compounds represented by the composition formula LiNi x Me 1 y Me 2 z O 2 In the formula, examples of Me 1 include Co, Fe, Mn, Mo, etc., and examples of Me 2 include Al, Ga, Si, Mg, Ti, Ba, Zr, Y, etc. x, y, and z are integers of 0 or more, and x + y + z = 1. Examples of the olivine-type lithium composite oxide include LiFePO 4 , LiFe 1-x Mn x PO 4 (where x is an integer of 0 or more) and the like. Examples of the spinel-type lithium composite oxide include LiMn 2 O 4 and the like.

[0072] The lithium composite oxide may contain at least one selected from the group consisting of F, Cl, N, S, Br, and I.

[0073] The shape of the positive electrode active material is not particularly limited. For example, it can be spherical (e.g., regular spherical, ellipsoidal, etc.), fibrous, or the like.

[0074] The particle diameter of the positive electrode active material can be from 0.1 μm to 30 μm.

[0075] The specific surface area of the positive electrode active material can be from 0.1 m 2 / g to 100 m 2 / g.

[0076] As the conductive agent, the same conductive agents as those exemplified for the negative electrode can be used. The content of the conductive agent relative to the positive electrode active material can be 3% by mass to 5% by mass.

[0077] As the binder, the same binders as those exemplified for the negative electrode can be used. The content of the binder relative to the positive electrode active material can be 0.1% by mass to 5% by mass.

[0078] Current collector

[0079] As the current collector, the current collectors exemplified in the negative electrode can be used. As the positive current collector, it is preferably made of Al.

[0080] The thickness of the current collector is not particularly limited. For example, it can be 0.1 μm to 1,000 μm.

[0081] Electrolyte layer

[0082] The electrolyte layer can include a solid electrolyte layer or a separator and an electrolytic solution.

[0083] When the electrolyte layer is a solid electrolyte layer, examples of the solid electrolyte include lithium lanthanum zirconium oxide, LiPON, Li 1+X Al X Ge 2-X (PO4) 3 , Li-SiO-based glass, Li-Al-S-O-based glass and other oxide solid electrolytes; Li 2 S-P 2 S 5 , Li 2 S-SiS 2 , LiI-Li 2 S-SiS 2 , LiI-Si 2 S-P 2 S 5 , Li 2 S-P 2 S 5 -LiI-LiBr, LiI-Li 2 S-P 2 S 5 , LiI-Li 2 S-P 2 O 5 , LiI-Li 3 PO 4 -P 2 S 5 , Li 2 S-P 2 S 5 -GeS 2 and other sulfide solid electrolytes. The solid electrolyte layer can be obtained by pressing the solid electrolyte.

[0084] When the electrolyte layer includes a separator and an electrolytic solution, examples of the separator include resin sheets such as polyethylene (PE) and polypropylene (PP). And the electrolytic solution contains a prescribed electrolyte and a solvent. Examples of the prescribed electrolyte include LiPF6 , LiBF 4 , LiAsF 6 , Li(CF 3 SO 2 ) 2 N, Li(C 2 F 5 SO 2 ) 2 N, LiTaF 6 , LiClO 4 , LiCF 3 SO 3 etc.

[0085] As solvents, for example, cyclic carbonate solvents such as ethylene carbonate (EC) and propylene carbonate (PC) can be cited; chain carbonate solvents such as dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC), etc. The concentration of the electrolyte solution can be 0.1 to 1 mol / L.

[0086] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to the following examples.

[0087] Manufacture of the negative electrode

[0088] Example 1

[0089] The first graphite with an aspect ratio of 2 to 5 and the second graphite with an aspect ratio of 1 to 1.4 were used. In the graphite mixture with a mixing ratio of the first graphite: the second graphite = 70:30 (mass ratio), carboxymethyl cellulose (CMC) as a thickener and styrene-butadiene rubber (SBR) as a binder were added in such a way that the first graphite, the second graphite: CMC: SBR = 98:1:1 (mass ratio). Further, water was added for kneading to prepare a slurry for forming the first negative electrode active material layer.

[0090] Next, when the above slurry was coated on a current collector (Cu foil) so that the weight per unit area became 20 mg / cm 2 , and an orientation treatment was performed thereon, a magnetic field of 0.5 T or more was applied in a direction perpendicular to the surface of the first negative electrode active material layer.

[0091] Next, the first negative electrode active material layer was dried and pressed so that the electrode density became 1.2 g / cm 3 to fabricate a negative electrode.

[0092] Evaluation of the negative electrode

[0093] XRD measurement

[0094] Regarding the fabricated negative electrode, the orientation of the first graphite in the first negative electrode active material layer was evaluated by the peak intensity ratio obtained from XRD measurement.

[0095] XRD measurement was performed using an XRD measurement device. The orientation of the first graphite was evaluated by the ratio (I 002 of the diffraction peak intensity I attributed to the plane index (002) (the direction perpendicular to the plane of the graphene structure) near 2θ = 26.3° 110 to the diffraction peak intensity I attributed to the plane index (110) (the in-plane direction of the graphene structure) near 2θ = 77.7°. 110 / I 002 ). The results are shown in Table 1.

[0096] Cell unit resistance

[0097] The performance of the negative electrode was evaluated using a half-cell unit with Li metal as the counter electrode. Specifically, the negative electrode was cut into a 5 cm square (excluding the current collector joint), opposed to Li metal with a 20-μm-thick three-layer separator of PP / PE / PP, and laminated and sealed together with EC / EMC = 30 / 70 (volume %) containing 1 M LiPF 6 to fabricate a half-cell unit. The half-cell unit was charged and discharged in the range of 0.05 V to 1.2 V (vs. Li / Li + ), and SOC100% was defined based on the capacity at this time. After adjusting the cell unit to SOC50%, it was charged at 1C for 10 minutes, and the absolute value of the voltage change (open-circuit voltage before evaluation - closed-circuit voltage after 10 minutes) at this time was divided by the 1C current value to calculate the cell unit resistance. The results are shown in Table 1. In addition, each resistance value is represented by a standard value with the resistance of Comparative Example 2 as the reference.

[0098] Example 2

[0099] In Example 1, a first negative electrode active material layer with the composition ratio shown in Table 1 was provided on the current collector, and except for this, a negative electrode was fabricated and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0100] Example 3

[0101] In Example 1, a first negative electrode active material layer with the composition ratio shown in Table 1 was provided on the current collector, and except for this, a negative electrode was fabricated and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0102] Example 4

[0103] Graphite having an aspect ratio of 1 to 1.4 (second graphite), carboxymethyl cellulose (CMC) as a thickener, and styrene-butadiene rubber (SBR) as a binder were added in such a manner that the ratio of graphite:CMC:SBR was 98:1:1 (by mass). By adding water and kneading, a slurry for forming the second negative electrode active material layer was prepared.

[0104] In Example 1, the slurry for forming the second negative electrode active material layer was coated on a current collector (Cu foil), and further, the first negative electrode active material layer having the composition ratio shown in Table 1 was provided thereon. Except for this, a negative electrode was produced and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0105] Comparative Example 1

[0106] In Example 1, the first negative electrode active material layer having the composition ratio shown in Table 1 was provided on the current collector, no magnetic field was applied, and except for this, a negative electrode was produced and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0107] Comparative Example 2

[0108] In Example 1, the first negative electrode active material layer having the composition ratio shown in Table 1 was provided on the current collector, and except for this, a negative electrode was produced and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0109] Comparative Example 3

[0110] In Example 1, the first negative electrode active material layer having the composition ratio shown in Table 1 was provided on the current collector, and except for this, a negative electrode was produced and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0111] Comparative Example 4

[0112] In Example 1, the first negative electrode active material layer having the composition ratio shown in Table 1 was provided on the current collector, and except for this, a negative electrode was produced and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0113] (Table 1)

[0114]

[0115] As shown in Table 1, in the first negative electrode active material layer, the mass ratio of the second graphite to the first graphite (mass % of the second graphite / mass % of the first graphite) in the cases where it was 30 / 70 to 70 / 30 (Examples 1 to 4) was compared with the case where the second graphite was not included or the case where the mass ratio of the first graphite to the second graphite deviated from the above range (Comparative Examples 2 to 4). I 110 / I 002Significantly increased. It was confirmed that the collapse of the first graphite caused by pressing was suppressed. I 110 / I 002 The increase is correlated with the decrease in the cell resistance. In Examples 1 to 4, a 20% to 30% decrease in the cell resistance was observed compared to the case where the second graphite was not included (Examples 1 to 4, Comparative Example 2).

[0116] On the other hand, in Comparative Example 3 where the mass ratio of the second graphite to the first graphite (mass % of the second graphite / mass % of the first graphite) was 10 / 90, no I 110 / I 002 significant increase was observed. Also, in Comparative Example 4 where the mass ratio of the second graphite to the first graphite (mass % of the second graphite / mass % of the first graphite) was 90 / 10, no I 110 / I 002 significant increase was observed. In the case of Comparative Example 4, it can be considered that this is because the proportion of the first graphite oriented by the magnetic field itself is small.

[0117] Also, it was found that the first graphite was temporarily oriented when a magnetic field was applied (Comparative Examples 1 and 2), but I 110 / I 002 was less than that of the randomly oriented graphite powder I 110 / I 002 0.014. Therefore, the first graphite became oriented to collapse in the in-plane direction of the negative electrode by pressing.

Claims

1. A negative electrode for a battery, characterized in that have: The first negative electrode active material layer comprises a first graphite having an aspect ratio of 2 to 5 and a second graphite having an aspect ratio of 1 to 1.4, wherein the peak intensity ratio I 110 / I 002 is 0.03 or more; and Current collector.

2. The negative electrode for a battery according to claim 1, characterized in that In the first negative electrode active material layer, a mass ratio of the second graphite to the first graphite is 30 / 70 to 70 / 30.

3. The negative electrode for a battery according to claim 1, characterized in that: A second negative electrode active material layer is further provided between the first negative electrode active material layer and the current collector, and the second negative electrode active material layer includes the second graphite and does not include the first graphite.

4. The negative electrode for a battery according to claim 3, characterized in that: The first negative electrode active material layer is provided as an outermost layer.

5. A battery, characterized in that: A negative electrode for a battery comprising the negative electrode according to any one of claims 1 to 4.

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