Electrode for energy storage device and lithium ion secondary battery

Abstract

An electrode for an electrical storage device includes: a resin layer having a first surface and a second surface opposite the first surface; a first conductive layer located on the first surface side of the resin layer; and a first particle layer located on the opposite side of the first conductive layer from the resin layer. In a cross-section parallel to the thickness direction of the resin layer, the first conductive layer has a first shape comprising a plurality of protrusions curved convexly toward the resin layer and a concave portion disposed between two adjacent protrusions. A distance H in the thickness direction from one of the apexes of the two adjacent protrusions to the bottom of the concave portion is smaller than the thickness of the resin layer.

Description

Technical Field

[0001] The present invention relates to an electrode for an electricity storage device and a lithium ion secondary battery. Background Art

[0002] As a current collector for a secondary battery, a composite material having metal layers formed on both sides of a resin film has been proposed. Patent Documents 1 and 2 below disclose electrodes for a secondary battery using such a composite material as a current collector.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: U.S. Patent Application Publication No. 2020 / 0373584

[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 2014-75191 Summary of the Invention

[0007] The technical problem that the invention aims to solve

[0008] In power storage devices such as lithium-ion secondary batteries, further improvement in rate characteristics is required.

[0009] One embodiment of the present invention provides an electrode for a power storage device capable of improving the rate characteristics of the power storage device.

[0010] Methods used to solve technical problems

[0011] An electrode for a storage device according to one embodiment of the present invention includes: a resin layer having a first surface and a second surface located on the opposite side of the first surface; a first conductive layer located on the first surface side of the resin layer; and a first particle layer located on the opposite side of the first conductive layer from the resin layer, wherein in a cross section parallel to the thickness direction of the resin layer, the first conductive layer has a first shape, the first shape including a plurality of protrusions bent into a convex shape toward the resin layer side and a concave portion arranged between two adjacent protrusions among the plurality of protrusions, and a distance H in the thickness direction from one of the vertices of the two adjacent protrusions to the bottom point of the concave portion is less than the thickness of the resin layer.

[0012] Another embodiment of the present invention relates to an electrode for a storage device, comprising: a resin layer having a first surface and a second surface located on the opposite side of the first surface; a first conductive layer located on the first surface side of the resin layer; and a first particle layer located on the opposite side of the first conductive layer from the resin layer, wherein the first conductive layer has a first shape in a cross section parallel to a thickness direction of the resin layer, the first shape being a first corrugated shape including a plurality of convex portions bent into a convex shape toward the resin layer side, and the amplitude of the first corrugated shape in the thickness direction is smaller than the thickness of the resin layer.

[0013] Effects of the Invention

[0014] According to an embodiment of the present invention, there is provided an electrode for a power storage device capable of improving the rate characteristics of the power storage device. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is an exploded perspective view of a first electrode showing one embodiment of the present disclosure.

[0016] Figure 2 Yes Figure 1 Schematic cross-sectional view of a portion of the cross section of the first electrode shown in FIG.

[0017] Figure 3 It is a schematic cross-sectional view showing a portion of the first electrode for explaining the shape of the first conductive layer.

[0018] Figure 4 Yes Figure 1 Schematic cross-sectional view of a portion of the cross section of the first electrode shown in FIG. 1 , which is parallel to the YZ plane.

[0019] Figure 5 This figure shows a part of the cross section of the first electrode and is a schematic diagram based on a cross-sectional SEM image.

[0020] Figure 6 This is a schematic cross-sectional view showing a portion of the first electrode for explaining the relationship between the particles of the granular layer and the first conductive layer.

[0021] Figure 7A This is a schematic cross-sectional view showing a portion of another example of the first electrode.

[0022] Figure 7B This is a schematic cross-sectional view showing a portion of another example of the first electrode.

[0023] Figure 8 This is a schematic cross-sectional view showing a portion of still another example of the first electrode.

[0024] Figure 9This is an exploded perspective view of a first electrode showing another embodiment of the present disclosure.

[0025] Figure 10 Yes Figure 1 Schematic cross-sectional view of a portion of the first electrode shown.

[0026] Figure 11 This is a schematic cross-sectional view showing a unit cross section of the first electrode for explaining a method of determining the Z direction.

[0027] Figure 12 This is a schematic cross-sectional view showing a portion of a unit cross section of the first battery for explaining the distance H.

[0028] Figure 13 This figure shows a part of the unit cross section of the first electrode and is a schematic diagram based on a cross-sectional SEM image.

[0029] Figure 14 Schematic cross-sectional view showing a part of a unit cross section of the first electrode for explaining the height d1 of the convex portion and the depth d2 of the concave portion.

[0030] Figure 15 Schematic diagram showing a unit cross section U2 - 1 of the battery 2 of Example 2 based on a cross-sectional SEM image.

[0031] Figure 16 This figure shows a part of the unit cross section of the first electrode and is a schematic diagram based on a cross-sectional SEM image.

[0032] Figure 17 Schematic cross-sectional view showing a unit cross section of the first electrode for explaining the parameter of the gap g.

[0033] Figure 18 This figure shows a part of the cross section of the laminated film before the particle layer is formed, and is a schematic diagram based on a cross-sectional SEM image.

[0034] Figure 19 This is a partially cutaway view showing an example of an electricity storage device.

[0035] Figure 20 It is from Figure 19 The illustrated electric storage device is an exploded perspective view showing a single cell removed therefrom.

[0036] Figure 21 This is a partial cross-sectional view showing another example of the electricity storage device.

[0037] Figure 22 It is from Figure 21 The illustrated power storage device is an exploded perspective view showing the cells and leads removed.

[0038] Figure 23Schematic diagram based on a cross-sectional SEM image showing a unit cross section U6 - 1 of the battery 6 of the example.

[0039] Description of Reference Numerals

[0040] 10: 1st conductive layer

[0041] 10a: Outer surface of the first conductive layer

[0042] 10b: Inner surface of the first conductive layer

[0043] 10X: Part 1 of the 1st conductive layer

[0044] 11: convex part

[0045] 11a: Vertex

[0046] 12: concave part

[0047] 12b: Bottom

[0048] 20: Second conductive layer

[0049] 20a: Outer surface of the second conductive layer

[0050] 20b: Inner surface of the second conductive layer

[0051] 21: convex part

[0052] 21a: Vertex

[0053] 22: concave part

[0054] 22b: Bottom

[0055] 30: Resin layer

[0056] 31: First surface of the resin layer

[0057] 31S: Reference plane

[0058] 32: Second surface of resin layer

[0059] 70: Solid layer

[0060] 100, 100A, 200, 200A: composite membrane

[0061] 100t, 200t: Tab area

[0062] 100a: Upper surface of composite membrane

[0063] 100b: lower surface of the composite membrane

[0064] 110, 110A: 1st electrode

[0065] 111, 112: Material layer (granular layer)

[0066] p1, p2, p3: particles

[0067] 120, 120A: Second electrode

[0068] 170, 170A: First floor

[0069] 211, 212: positive electrode material layer

[0070] 250, 260: Lead

[0071] 290: Electrolytes

[0072] 300: Exterior body

[0073] 311, 321: convex area

[0074] 312, 322: concave area

[0075] 1001, 1002: Energy storage device (lithium-ion secondary battery)

[0076] 2001, 2002: Single battery DETAILED DESCRIPTION

[0077] The following describes embodiments of the present disclosure with reference to the accompanying drawings. The numerical values, shapes, materials, steps, and the order of these steps shown in the following description are merely examples and can be modified in various ways without creating technical conflicts. Furthermore, the embodiments described below are merely examples and can be combined in various ways without creating technical conflicts.

[0078] For ease of explanation, the sizes, shapes, etc. of the components shown in the drawings of the present disclosure are sometimes exaggerated. In addition, in the drawings of the present disclosure, in order to avoid excessive complexity, some components are sometimes taken out for illustration, or the illustration of some elements is omitted. Therefore, the sizes of the components and the configuration between the components shown in the drawings of the present disclosure sometimes do not reflect the sizes of the components and the configuration between the components in the actual device. The "vertical" and "orthogonal" in the present disclosure are not limited to two straight lines, edges, surfaces, etc. that are strictly at an angle of 90°, but also include situations where they are within a range of 90°±5°. In addition, "parallel" includes situations where two straight lines, edges, surfaces, etc. are within a range of 0°±5°.

[0079] In this specification, the term "single cell" refers to a structure in which at least one pair of positive and negative electrodes are integrally assembled. The term "battery" in this specification is used to encompass various configurations, such as battery modules and battery packs, that include one or more electrically connected "single cells."

[0080] (Implementation Method)

[0081] One embodiment of the electrode for a storage device disclosed herein (hereinafter referred to as the "electrode") includes: a resin layer having a first surface and a second surface; a first conductive layer located on the first surface of the resin layer; and a first particle layer. The "particle layer" is a layer containing a plurality of particles, and the layer may also contain materials other than particles. The shape and size of the particles are not particularly limited as long as the first particle layer can be fixed to the resin layer. The first particle layer is located on the side of the first conductive layer opposite to the resin layer. The first particle layer is, for example, an active material particle layer containing a plurality of active material particles.

[0082] In the electrode of this embodiment, the laminated film including the first conductive layer and the resin layer can function as a current collector. In this specification, such a laminated film is sometimes referred to as a "composite film". The composite film may also have a conductive layer located on the second surface of the resin layer. That is, the composite film may have a laminated structure in which conductive layers are respectively provided on both sides of the resin layer. In this case, the conductive layer formed on the second surface of the resin layer is referred to as the "second conductive layer". The second conductive layer may also have a shape including a plurality of protrusions that are convexly bent toward the resin layer side in a cross section parallel to the thickness direction of the particle layer, similarly to the first conductive layer. Such a cross-sectional shape is referred to as the "second shape". In this specification, the first conductive layer and the second conductive layer are sometimes collectively referred to as the "conductive layer".

[0083] The electrode of this embodiment can be used as a positive electrode, a negative electrode, or both of an electrical storage device such as a lithium-ion secondary battery. The electrical storage device can have a single-layer cell consisting of a pair of positive and negative electrodes, or a stacked cell having multiple pairs of positive and negative electrodes. In these electrical storage devices and cells, one of the positive and negative electrodes is sometimes referred to as the "first electrode," and the other is sometimes referred to as the "second electrode." In addition, the positive and negative electrodes are sometimes collectively referred to as "electrodes."

[0084] Hereinafter, an electrode according to this embodiment and an electricity storage device using this embodiment will be described in more detail with reference to the drawings.

[0085] [Electrode structure]

[0086] Figure 1 and Figure 2 Schematic diagram showing an example of an electrode for a power storage device (hereinafter simply referred to as “electrode”) according to the present embodiment. Figure 1 is a schematic exploded view of the electrode. Figure 2 yes Figure 1 The schematic cross-sectional view of the electrodes shown in the figure also includes an enlarged cross-sectional view of the area enclosed by the dashed line. For simplicity, the electrodes used in a single-layer cell having only a pair of positive and negative electrodes are shown. In this specification, for ease of explanation, arrows indicating three mutually orthogonal directions, namely the X, Y, and Z directions, are shown in the drawings. Figure 2 It shows the cross section parallel to the Z direction (cross section perpendicular to the XY plane).

[0087] like Figure 1 As shown, the first electrode 110 includes a composite film 100 and a first material layer 111 supported by the composite film 100. The composite film 100 has an upper surface 100a and a lower surface 100b. The first material layer 111 is arranged on the upper surface 100a of the composite film 100. In the illustrated example, the first material layer 111 is arranged only on a portion of the composite film 100. The composite film 100 includes a region 110e that overlaps with the first material layer 111 when viewed in the Z direction, and a tab region 100t that is located outside the first material layer 111 when viewed in the Z direction (does not overlap with the first material layer 111). The tab region 100t is used, for example, for connection to a lead.

[0088] like Figure 2 As shown in FIG. 1 , the composite film 100 includes a resin layer 30 and a first conductive layer 10 supported by the resin layer 30. Figure 2 In the example shown, the resin layer 30 , the first conductive layer 10 , and the first material layer 111 are stacked along the Z direction. The Z direction is sometimes referred to as the “thickness direction of the resin layer 30 ”.

[0089] The resin layer 30 has a first surface 31 and a second surface 32 located opposite to the first surface 31. The resin layer 30 has a thickness T. As described later, the thickness T is, for example, an average distance between the first surface 31 and the second surface 32 in the Z direction.

[0090] The first conductive layer 10 is located on the first surface 31 side of the resin layer 30. The first conductive layer 10 has an outer surface 10a located on the opposite side to the resin layer 30 and an inner surface 10b located on the resin layer 30 side.

[0091] The first material layer 111 is located on the side of the first conductive layer 10 opposite to the resin layer 30. That is, the first material layer 111 is located on the outer surface 10a side of the first conductive layer 10. The first material layer 111 is a particle layer containing a plurality of particles. As described above, a "particle layer" only needs to be a layer containing a plurality of particles, and may also contain substances other than particles (such as a binder). The material of the plurality of particles is not particularly limited. The plurality of particles may include, for example, active material particles, conductive particles, or both.

[0092] In the example shown in the figure, the upper surface 100a of the composite film 100 is, for example, the outer surface 10a of the first conductive layer 10. The lower surface 100b of the composite film 100 is, for example, the second surface 32 of the resin layer 30. As described later, the composite film 100 may also have a second conductive layer located on the side of the second surface 32 of the resin layer 30. In this case, the lower surface 100b of the composite film 100 may also be the outer surface of the second conductive layer. In addition, in this specification, terms such as "upper surface", "lower surface", "upper layer" and "lower layer" containing "upper" or "lower" are sometimes used. However, this is for the convenience of explaining the relative configuration between components and is not intended to limit the posture of the storage device during use. For example, the "upper surface" refers to the surface located on the positive side of the Z direction in the figure, and the "lower surface" refers to the surface located on the negative side of the Z direction in the figure.

[0093] Next, refer to Figure 2 The electrode structure of this embodiment is described in more detail in the enlarged view shown in FIG. In this specification, the shapes of the first conductive layer and the resin layer are described primarily using cross sections parallel to the Z direction. In the following description, "in a cross section parallel to the Z direction" may be simply referred to as "in a cross-sectional view."

[0094] <First Shape of First Conductive Layer>

[0095] like Figure 2 As shown in the enlarged view, in a cross section parallel to the Z direction, the first conductive layer 10 of the first electrode 110 has a first shape including a plurality of protrusions (sometimes referred to as "first protrusions") 11. The first shape may further include a concave portion 12 (sometimes referred to as "first concave portion") located between two adjacent protrusions 11. Figure 2 In the example shown, the first shape has a plurality of convex portions 11 and a plurality of concave portions 12 .

[0096] Each convex portion 11 is a curved portion that is bent into a convex shape toward the resin layer 30 side in the cross-sectional view. That is, both surfaces of the first conductive layer 10 (the outer surface 10a and the inner surface 10b) are bent into a convex shape toward the resin layer 30 side at the convex portion 11. In the example shown in the figure, the "resin layer side" is the negative side (-Z side) in the Z direction. In the convex portion 11, the outer surface 10a and the inner surface 10b of the first conductive layer 10 are bent into a convex shape in the same direction (resin layer 30 side), but they do not have to be parallel to each other. In the cross-section parallel to the Z direction, the convex portion 11 as a whole can be bent into a convex shape toward the resin layer 30 side, and the upper surface and / or lower surface of the convex portion 11 (in this example, the portion of the outer surface 10a and the inner surface 10b of the first conductive layer 10 located in the convex portion 11) may also include a flat surface represented by a step, a straight line, etc.

[0097] In this specification, when a layer (or surface) is "curved" in a cross-sectional view, it means that the cross-sectional shape of the layer (or surface) is curved as a whole. Therefore, in a cross-sectional view, a "curved shape" includes not only shapes composed of one or more arcuate portions without corners, but also shapes composed of arcuate portions and straight portions. "Arcuate" refers to a curved shape in a cross-sectional view and is not limited to a shape having an arch or depicting a circular arc.

[0098] Each convex portion 11 has a vertex 11a. The "vertex of the convex portion" is, for example, a point on the inner surface 10b of the first conductive layer 10 that is closest to the -Z side (i.e., the second surface 32 side of the resin layer 30) of the convex portion 11 in a cross section parallel to the Z direction. Figure 2 In the illustrated cross-section, apex 11a is a point that represents the minimum point on the resin layer side of the surface of the convex portion 11. In other words, each vertex 11a corresponds to a point in the cross-sectional view that represents the minimum point when the shape of the inner surface 10b is viewed as a curve. The convex portion 11 may also have a substantially flat top surface. If the top surface of the convex portion 11 is parallel to the XY plane, the vertex 11a may be any point on the top surface.

[0099] Each concave portion 12 only needs to be a portion located between two adjacent convex portions 11, and the cross-sectional shape of the concave portion 12 is not particularly limited. Each concave portion 12 may include a curved portion that is curved into a concave shape relative to the resin layer 30 in the cross-sectional view, or may include a flat portion that is not curved. Alternatively, it may include a curved portion that is curved into a concave shape and a flat portion. The "flat portion" includes, for example, a portion represented by parallel straight lines on the outer surface 10a and the inner surface 10b of the first conductive layer 10 in the cross-sectional view. Figure 2 In the illustrated cross section, each recessed portion 12 is curved into a concave shape relative to the resin layer 30. That is, the outer surface 10a and the inner surface 10b of the first conductive layer 10 are curved into a concave shape relative to the resin layer 30 in the recessed portion 12. In the recessed portion 12, the outer surface 10a and the inner surface 10b of the first conductive layer 10 are curved in the same direction, but do not necessarily need to be parallel to each other.

[0100] Each recess 12 has a bottom point 12b. The "bottom point of the recess" is, for example, a point on the inner surface 10b of the first conductive layer 10 that is located on the most +Z side of the recess 12 in a cross section parallel to the Z direction. In the illustrated cross section, the bottom point 12b is a point that is a maximum point on the surface of the recess 12 on the resin layer side. In other words, each bottom point 12b is a point in the cross-sectional view that corresponds to a maximum point when the shape of the inner surface 10b is viewed as a curve. In addition, the surface of each recess 12 on the resin layer side may have a bottom surface parallel to the XY plane. In this case, the bottom point may be any point on the bottom surface.

[0101] The boundary between the convex portion 11 and the concave portion 12 can be defined, for example, as follows. Figure 3 This is a partially enlarged view for illustrating the shape of the first conductive layer. In a cross section parallel to the Z direction, the curve representing the inner surface 10b of the first conductive layer 10 includes, for example, a vertex (here, a minimum point) 11a1 of a convex portion 11, a bottom point (here, a maximum point) 12b1 of a concave portion 12 located on the -X side of the convex portion 11, a bottom point 12b2 of the concave portion 12 located on the +X side of the convex portion 11, an inflection point c1 located between the vertex 11a1 and the bottom point 12b1, and an inflection point c2 located between the vertex 11a1 and the bottom point 12b2. An "inflection point" refers to a point at which the curve changes from being downwardly convex to being upwardly convex, or vice versa. A line 15 parallel to the Z direction passing through the inflection point c1 and a line 16 parallel to the Z direction passing through the inflection point c2 can also be used as the boundary lines between the convex portion 11 and the concave portions 12 located on both sides thereof, respectively. The width of the protrusion 11 in the X direction is, for example, the distance between the line 15 and the line 16. In a cross section parallel to the Z direction, if the line representing the inner surface 10 b of the first conductive layer 10 includes a step or a straight portion, an approximate curve representing the inner surface 10 b can be obtained by, for example, image analysis, and the inflection point can be determined from this curve.

[0102] In this embodiment, if Figure 2 As shown, in a cross section parallel to the Z direction, the distance H in the Z direction from one of the apexes 11a of two adjacent convex portions 11 of the first conductive layer 10 to the bottom 12b of the concave portion 12 is smaller than the thickness T of the resin layer 30. For example, in a cross section parallel to the Z direction and having a predetermined width (a width perpendicular to the Z direction), the distance H between each of the plurality of convex portions 11 may be smaller than the thickness T. The predetermined width may be, for example, the reference length L (e.g., 25 μm) described later.

[0103] like Figure 2As shown, the first shape of the first conductive layer 10 may also be a wavy shape. "Wave-shaped" includes, for example, a shape such as a "wave" having a plurality of convex portions 11 and a plurality of concave portions 12 repeatedly. In the wavy shape, convex portions 11 that are bent into a convex shape toward the resin layer 30 side and concave portions 12 that include a portion bent into a concave shape toward the resin layer 30 side may be alternately arranged. The wavy shape includes a shape in which the height, amplitude or wavelength of the wave changes randomly. In addition, the first conductive layer 10 as a whole may have a wavy shape, for example, it may include a flat portion between the convex portions. In the example shown in the figure, the wavy shape of the first conductive layer 10 (sometimes referred to as "the first wavy shape") has an amplitude Am that is smaller than the thickness T of the resin layer 30. The amplitude Am can be obtained, for example, using image analysis software based on the contour of the inner surface 10b of the first conductive layer 10 in a cross section parallel to the Z direction. Observation, analysis, measurement, etc. of the amplitude may also be performed by other methods. Observation can be performed by preparing a sample for observation. For example, an electrode is embedded in a resin, and after exposing a cross section by grinding, the cross section is precisely machined by ion milling to produce an observation sample. The amplitude Am can then be determined by observing and analyzing the observation sample using, for example, a microscope manufactured by KEYENCE CORPORATION. Alternatively, for example, the amplitude of the waveform can be determined by determining half the distance in the Z direction between the point closest to the -Z side and the point closest to the +Z side of the waveform based on a cross-sectional photograph parallel to the Z direction and having a predetermined width (reference length L).

[0104] In this specification, "the first shape" and "the wavy shape" also include shapes in which the arrangement of the concave portions 12 and the convex portions 11 is irregular. For example, the distance between the vertices 11a of two adjacent convex portions 11 in the X direction (equivalent to the wavelength of the waveform) may not be fixed. As shown in the figure, the arrangement spacing of the convex portions 11 may also be random. The arrangement spacing of the convex portions 11 is, for example, the distance in the X direction between the vertices 11a of the convex portions 11. In addition, the sizes of the plurality of convex portions 11 and the sizes of the plurality of concave portions 12 may also be uneven. As described later, the arrangement spacing of the convex portions 11, the sizes of the convex portions 11 and the concave portions 12, etc. in the first shape can be obtained based on a microscope image showing a cross section parallel to the Z direction.

[0105] Figure 2 The enlarged view shown shows a cross section parallel to the X direction (XZ cross section) of the first electrode 110. The first conductive layer 10 of this embodiment may have a first shape including a plurality of protrusions 11 in a cross section perpendicular to the XY plane and parallel to another direction intersecting the X direction (e.g., the Y direction).

[0106] Figure 4 It will Figure 1 FIG. 1 is a schematic diagram showing a part of the YZ cross section of the first electrode 110, which is enlarged. Figure 4 As shown, in a cross section parallel to the Y direction, which is perpendicular to the X direction, the first conductive layer 10 also has a first shape including multiple protrusions 11. Although cross sections in directions other than the X and Y directions are not shown, the first conductive layer 10 can also have the first shape in cross sections taken in three or more different directions in the XY plane. This can suppress stress concentration within the plane of the first conductive layer 10 and more evenly alleviate stress. The multiple protrusions 11 can also be randomly arranged in the XY plane.

[0107] Furthermore, the arrangement of the convex portions 11 and concave portions 12 in the first shape is not limited to the above. Multiple convex portions 11 and multiple concave portions 12 may be regularly arranged. "Regularly arranged" also includes arrangements in which the pitch of the convex portions, the size of the convex portions and / or the concave portions, etc., vary periodically.

[0108] exist Figure 2 In the illustrated first electrode 110, the first conductive layer 10, supported by the resin layer 30, has the first shape described above, and the thickness T of the resin layer 30 is greater than the distance H of the first shape. Alternatively, the first shape of the first conductive layer 10 is a corrugated shape with an amplitude Am smaller than the thickness T of the resin layer 30. Thus, the deformation of the first conductive layer 10 and the resin layer 30 can alleviate the stress applied to the first conductive layer 10 by the first material layer 111, which serves as the granular layer. Consequently, degradation of the first electrode 110, such as a decrease in conductivity, can be suppressed. The "stress applied to the first conductive layer from the first material layer" referred to herein can include stress applied to the first conductive layer 10 during the process of forming the granular layer on the first conductive layer 10 (e.g., a calendering process), stress applied to the first conductive layer 10 due to the expansion and contraction of the granular layer during operation of the energy storage device, and other stresses. As described later, the first electrode 110 may have a gap between the first conductive layer 10 having the first shape and the resin layer 30. This can reduce the internal stress of the first conductive layer 10 generated when the first conductive layer 10 is formed, and thus can suppress a decrease in conductivity due to the internal stress.

[0109] ·First shape formation area

[0110] Reference Figure 2, an example of a range in which the first shape is formed is described. The first conductive layer 10 only needs to have the first shape at least partially. The portion having the first shape in the first conductive layer 10 is referred to as the "first region". The first region at least partially overlaps with the first material layer 111 in the Z direction. In the Z direction, the entire first region can overlap with the first material layer 111. That is, the first shape can also be formed over the entire region 100e of the first electrode 110 that overlaps with the first material layer 111 in the Z direction. The first conductive layer 10 has the first shape between the first material layer 111 and the resin layer 30, thereby alleviating the stress applied to the first conductive layer 10 due to the expansion / contraction of the first material layer 111 in the energy storage device using the first electrode 110.

[0111] As an example, the portion of the first conductive layer 10 located in region 100e may be a first region having a first shape, while the portion located in the tab region 100t may be a flat region. For example, the flat region is a region where the inner surface 10b and the outer surface 10a of the first conductive layer 10 are parallel to the XY plane. The flat region includes a region where the height difference of the inner surface 10b of the first conductive layer 10 in the Z direction is within 5% of the thickness of the first conductive layer 10 in the tab region 100t.

[0112] <Shape of the First Surface of the Resin Layer>

[0113] like Figure 2 As shown, in a cross section parallel to the Z direction, the first surface 31 of the resin layer 30 may include a plurality of concave regions (sometimes referred to as "first concave regions") 312. The first surface 31 may also include a convex region (sometimes referred to as "first convex region") 311 between two adjacent concave regions 312 among the plurality of concave regions 312. In this embodiment, the first surface 31 of the resin layer 30 includes a plurality of concave regions 312 and a plurality of convex regions 311.

[0114] Each concave region 312 is a region curved into a concave shape in the first surface 31 in a cross-sectional view, and includes, for example, a “depression” formed in the first surface 31. Figure 2 In the example shown, each concave region 312 is arranged in the Z direction corresponding to one of the plurality of convex portions 11 in the first conductive layer 10. "Arranged corresponding to a convex portion 11" includes the case where each concave region 312 at least partially overlaps with the corresponding convex portion 11 when viewed in the Z direction. For example, when viewed in the Z direction, the point of each concave region 312 located closest to the -Z side may overlap with the corresponding convex portion 11.

[0115] The convex region 311 may be a convexly curved region or a substantially flat region (e.g., parallel to the XY plane). Each convex region 311 may be arranged in the Z direction corresponding to one of the plurality of concave portions 12 in the first conductive layer 10. That is, when viewed in the Z direction, each convex region 311 may at least partially overlap with a corresponding concave portion 12. For example, when viewed in the Z direction, the point of each convex region 311 located closest to the +Z side may overlap with a corresponding concave portion 12.

[0116] The arrangement of the concave regions 312 in the first surface 31 of the resin layer 30 may be random. In addition, the sizes of the concave regions 312 and the convex regions 311 may be non-uniform.

[0117] The first surface 31 of the resin layer 30 may also have a corrugated shape including a plurality of concave regions 312, for example. The first surface 31 may also have convex regions 311 and concave regions 312 arranged alternately. Furthermore, the term "corrugated shape," like the corrugated shape in the first conductive layer 10, includes a shape in which the arrangement of the concave regions 312 is irregular. Furthermore, the first surface 31 may have a corrugated shape as a whole; for example, it may have flat portions between the concave regions 312.

[0118] In the illustrated example, the resin layer 30 is in direct contact with the first conductive layer 10, but a gap may be partially formed between the resin layer 30 and the first conductive layer 10. As will be described later, another solid layer may be interposed between the resin layer 30 and the first conductive layer 10.

[0119] <Relationship between the Shape of the First Conductive Layer and the Resin Layer and the Particle Layer>

[0120] Next, an example of the relationship between one particle in the first material layer serving as the particle layer, the first shape of the first conductive layer, and the shape of the first surface of the resin layer will be described.

[0121] Figure 5 FIG. 1 is a diagram showing a portion of the cross section of the first electrode 110, and is a schematic diagram based on a cross-sectional SEM image obtained by observation using a scanning electron microscope (SEM). Figure 5As shown, in a cross-section parallel to the Z direction, among the multiple particles contained in the first material layer (particle layer) 111, a particle p1 located near the interface between the first material layer 111 and the composite film 100 can also be arranged corresponding to a protrusion 11p in the first conductive layer 10. Furthermore, the protrusion 11p can also be arranged corresponding to a concave region 312p in the resin layer 30. Similarly, another particle q1 can be arranged corresponding to a protrusion 11q in the first conductive layer 10, and the protrusion 11q can be arranged corresponding to a concave region 312q in the resin layer 30. As described above, "correspondingly arranged" includes at least partial overlap in the Z direction. As shown in the figure, the thickness of the first conductive layer 10 can be smaller in the portion overlapping with the particle p1 in the Z direction than in the portions on either side thereof. In other words, the thickness of the first conductive layer 10 is smaller at the protrusion 11p than at the concave region 12. Here, "the thickness of the first conductive layer" refers to the distance in the Z direction between the outer surface 10a and the inner surface 10b of the first conductive layer 10.

[0122] Figure 6 1 is a schematic cross-sectional view for explaining the relationship between one particle p1 of the first material layer 111, the first conductive layer 10, and the first surface 31 of the resin layer 30. Figure 6 As shown, in a cross section parallel to the Z direction, at least a portion of the particles p1 included in the first material layer 111 is located between two recesses 12 located on either side of a protrusion 11p in the first conductive layer 10. The particles p1 are, for example, active material particles. The particles p1 may or may not be in direct contact with the upper surface of the protrusion 11p. At least a portion of the protrusion 11p may be located within a recessed region 312p of the resin layer 30. In this example, the protrusion 11p is in direct contact with the upper surface of the recessed region 312p, but this contact is not required.

[0123] Based on this relationship, it can be said that the protrusions 11p in the first conductive layer 10 receive at least a portion of the particles p1 contained in the first material layer 111. Alternatively, it can be said that the first conductive layer 10 is curved to receive (contain) at least a portion of the particles p1.

[0124] In the illustrated example, the concave region 312p in the resin layer 30 receives at least a portion of the convex portion 11p in the first conductive layer 10. That is, at least a portion of the convex portion 11p is accommodated within the concave region 312p. Alternatively, each concave region 312p may receive at least a portion of a corresponding convex portion 11p.

[0125] Due to the aforementioned relationship between the particles p1, the first conductive layer 10, and the resin layer 30, for example, in a battery using the first electrode 110, the forces caused by the expansion and contraction of the particles (e.g., active material particles) p1 contained in the first material layer 111 can be absorbed by localized deformation of the protrusions 11 of the first conductive layer 10 and the concave regions 312 of the resin layer 30. As a result, significant deformation of the composite film 100 as a whole, the formation of significantly thinned portions in the first conductive layer 10, or the occurrence of cracks (crazing) or damage due to the expansion and contraction of the particles p1 can be suppressed, thereby suppressing increases in the resistance of the first conductive layer 10.

[0126] To achieve the above-described structure, for example, the distance Lb in the X direction between the bottom points 12b of the two recesses 12 located on either side of the protrusion 11p may be set to be at least one and no more than three times the size of the particle p1 (e.g., the maximum width in the X direction). As an example, when the maximum width Lp in the X direction of the particle p1 in the first material layer 111 is 2 to 3 μm in a cross-section observed using an SEM, the distance Lb may be set to be 4 to 9 μm.

[0127] Furthermore, at least one protrusion 11 in the first conductive layer 10 only needs to receive particles from the first material layer 111, and not all protrusions 11 need to be arranged corresponding to particles. Similarly, at least one concave region 312 in the resin layer 30 only needs to be arranged corresponding to a protrusion 11 that receives particles. Furthermore, if other layers are present between the resin layer 30 and the first conductive layer 10, concave regions corresponding to particles and protrusions may not be formed on the first surface 31 of the resin layer 30.

[0128] <Gap between First Conductive Layer and Resin Layer>

[0129] Figure 7A and Figure 7B Each of them is a schematic enlarged cross-sectional view showing another example of the first electrode, and shows the vicinity of the interface between the first conductive layer 10 and the resin layer 30 .

[0130] like Figure 7A As shown, the first electrode 110 may have one or more gaps (gap) g between the inner surface 10b of the first conductive layer 10 and the first surface 31 of the resin layer 30 in a cross section parallel to the Z direction. Each gap g is located between two of the plurality of protrusions 11 in a direction perpendicular to the Z direction (here, the X direction). The gap g may include an air layer. Other substances such as an electrolyte may also be contained within the gap g.

[0131] In this specification, a "gap" refers to a portion (e.g., a space) generated by partial separation of two upper and lower adjacent solid layers (referred to as the "first solid layer" and the "second solid layer") in the Z direction among a plurality of solid layers stacked along the Z direction in the first electrode 110. The gap g can be an internal space surrounded by the first solid layer and the second solid layer. In the example shown in the figure, the first solid layer is the resin layer 30, and the second solid layer is the first conductive layer 10, and the gap g is formed by partial separation of the resin layer 30 from the first conductive layer 10. In addition, the gap g only needs to be arranged between the first conductive layer 10 and the first surface 31 of the resin layer 30 in the Z direction. As described later, when another solid layer is provided between the first conductive layer 10 and the resin layer 30, a gap can also be provided between the other solid layer and the resin layer 30 or the first conductive layer 10.

[0132] exist Figure 7A In the example shown, two gaps g are arranged between two adjacent protrusions 11 of the first conductive layer 10. The gap g is, for example, an air layer. The gap g is located between the inner surface 10b of the first conductive layer 10 and the first surface 31 of the resin layer 30, and is in contact with the inner surface 10b and the first surface 31. The gap g may also be surrounded by the inner surface 10b and the first surface 31. In other words, the first conductive layer 10 has a portion in contact with the first surface 31 of the resin layer 30 and a first portion 10X spaced apart from the first surface 31. Here, the "protrusion in contact with the first surface" includes a case where at least a portion of the protrusion 11 (for example, a portion including the vertex 11a of the protrusion 11) is in contact with the first surface 31. The first portion 10X is not in contact with the first surface 31. The first portion 10X is arranged between the two protrusions 11 in contact with the first surface 31 of the resin layer 30.

[0133] like Figure 7B As shown, the gap g may extend over two or more convex portions 11 in a direction perpendicular to the Z direction. In the example shown in the figure, the first conductive layer 10 has a convex portion 11i, a convex portion 11j, and a convex portion 11k in the +X direction. The gap g extends between the convex portion 11i and the convex portion 11k from the convex portion 11i side beyond the convex portion 11j to the convex portion 11k side along the +X direction. In this case, the portion of the first conductive layer 10 that contacts the gap g as a whole becomes one first portion 10X. That is, in the example shown in the figure, in the first conductive layer 10, the first portion 10X is located between the two convex portions 11i and 11k that contact the first surface 31 of the resin layer 30.

[0134] If the gap g is provided between the first conductive layer 10 and the resin layer 30 , the internal stress of the first conductive layer 10 can be reduced. In addition, the stress applied to the first conductive layer 10 from the first material layer 111 can be more effectively relaxed.

[0135] The inner surface 10b of the first conductive layer 10 is preferably in contact with the gap g. This can more effectively reduce the internal stress of the first conductive layer 10. The phrase "inner surface 10b is in contact with the gap g" includes the case where a portion of the inner surface 10b is part of the surface defining the gap g. The gap g includes an air layer, and more preferably, the inner surface 10b of the first conductive layer 10 is in contact with the air layer. This can more effectively alleviate the internal stress of the first conductive layer 10.

[0136] Figure 8 This is a partial cross-sectional view showing another example of an electrode. Figure 8 In the example shown, another solid layer 70 is provided between the first conductive layer 10 and the resin layer 30. In such a structure, the gap g may be provided, for example, between the first conductive layer 10 and the solid layer 70. Although not shown, the gap g may also be provided between the solid layer 70 and the resin layer 30.

[0137] <Modification of Electrode>

[0138] The electrode of this embodiment may further include a second conductive layer on the second surface of the resin layer. Alternatively, a second particle layer may be provided on the side of the second conductive layer opposite the resin layer. Such an electrode can be used, for example, in a stacked cell having multiple pairs of positive and negative electrodes.

[0139] Figure 9 This is a schematic exploded view showing another example of the electrode according to this embodiment. Figure 10 yes Figure 9 The schematic cross-sectional view of the electrode shown also shows an enlarged cross-sectional view of the region surrounded by the dotted line in the figure. Figure 10 It is a cross section parallel to the Z direction. Figure 2 The same components are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

[0140] like Figure 9 As shown, the first electrode 110A includes: a composite film 100A having an upper surface 100a and a lower surface 100b; a first material layer 111 located on the upper surface 100a of the composite film 100A; and a second material layer 112 located on the lower surface 100b of the composite film 100A. Figure 1 Similarly to the electrode 110 shown, the first material layer 111 and the second material layer 112 may not be provided in the tab region 100 t of the composite film 100A.

[0141] like Figure 10 As shown, the composite film 100A includes a resin layer 30, a first conductive layer 10, and a second conductive layer 20. In the cross-sectional view, the second material layer 112, the second conductive layer 20, the resin layer 30, the first conductive layer 10, and the first material layer 111 are stacked in the Z direction.

[0142] The first electrode 110A includes the first conductive layer 10 and the first material layer 111 on the first surface 31 side of the resin layer 30. The shape of the first surface 31 of the resin layer 30 and the first shape of the first conductive layer 10 can be compared with the reference Figure 2 The shapes are the same.

[0143] The first electrode 110A includes the second conductive layer 20 and the second material layer 112 on the second surface 32 side of the resin layer 30. Figure 2 The first electrode 110 shown is different.

[0144] The second conductive layer 20 is located on the second surface 32 side of the resin layer 30. The second conductive layer 20 may include the same conductive material as the first conductive layer 10. The second conductive layer 20 has an outer surface 20a located opposite to the resin layer 30 and an inner surface 20b located on the resin layer 30 side.

[0145] The second material layer 112 is located on the side of the second conductive layer 20 opposite the resin layer 30. Specifically, the second material layer 112 is located on the outer surface 20a side of the second conductive layer 20. The second material layer 112 is a granular layer containing a plurality of particles. The second material layer 112 can be made of the same material as the first material layer 111.

[0146] like Figure 10 As shown in the enlarged view, in a cross section parallel to the Z direction, the second conductive layer 20 may also have a second shape including a plurality of protrusions 21 that are bent into a convex shape toward the resin layer 30 side. The second shape may be the same shape as the first shape of the first conductive layer 10. That is, in a cross section parallel to the Z direction, the second conductive layer 20 may also include a plurality of recesses 22. Each recess 22 is located, for example, between two adjacent protrusions 21 among the plurality of protrusions 21. Each recess 22 may be bent into a concave shape relative to the resin layer 30, or may be roughly flat. In addition, in the second conductive layer 20, the distance H in the Z direction from one of the apexes 21a of the two adjacent protrusions 21 to the bottom point 22b of the recess 22 may also be smaller than the thickness T of the resin layer 30. The second shape may also be a wavy shape (sometimes referred to as a "second wavy shape"). The wavy shape has an amplitude Am that is smaller than the thickness T of the resin layer 30. By providing the second conductive layer 20 with the second shape, stress applied to the second conductive layer 20 from the second material layer 112 can be alleviated.

[0147] The second surface 32 of the resin layer 30 may also include a plurality of concave regions 322 arranged corresponding to the convex portions 21, similar to the first surface 31. Each concave region 322 is a region that is concavely curved toward the first surface 31 side (in the illustrated example, the positive side in the Z direction). The second surface 32 may also include a plurality of convex regions 321. Each convex region 321 is, for example, located between two adjacent concave regions 322 among the plurality of concave regions 322. The convex region 321 may be a region that is convexly curved toward the first conductive layer 10 side, or may be substantially flat (for example, substantially parallel to the XY plane).

[0148] Each concave region 322 is arranged in the Z direction corresponding to one of the plurality of convex portions 21 in the second conductive layer 20. For example, when viewed from the Z direction, each concave region 322 may at least partially overlap with a corresponding convex portion 21. Alternatively, for example, when viewed from the Z direction, the point of each concave region 322 located closest to the first surface 31 side (+Z side) may overlap with the corresponding convex portion 21.

[0149] The first electrode 110A may have one or more gaps g between the inner surface 20b of the second conductive layer 20 and the second surface 32 of the resin layer 30 in a cross section parallel to the Z direction. Each gap g is located between two adjacent protrusions 21 among the plurality of protrusions 21. The positional relationship between the gap g, the second conductive layer 20, and the resin layer 30 can be similar to that described in reference to FIG. Figure 7A and Figure 7B The gap g is similar to the relationship between the first conductive layer 10 and the resin layer 30. The gap g provided by the first electrode 110A between the second conductive layer 20 and the resin layer 30 can alleviate the internal stress of the second conductive layer 20, thereby suppressing a decrease in conductivity caused by the internal stress of the second conductive layer 20.

[0150] In addition, the cross-sectional shape of the second conductive layer 20 is not particularly limited. The cross-sectional shape of the second conductive layer 20 may not have the second shape. For example, the outer surface 20a and the inner surface 20b of the second conductive layer 20 may also be substantially flat surfaces. However, as shown in the figure, it is preferred that both the first conductive layer 10 and the second conductive layer 20 have a convex portion that curves toward the resin layer 30. This can alleviate the stress from the first material layer 111 and the second material layer 112 arranged on both sides of the composite film 100A. Therefore, deformation or degradation of the composite film 100A can be suppressed, so the increase in the resistance of the first electrode 110A can be suppressed.

[0151] Relationship between the first shape and the second shape

[0152] An example of the relationship between the first shape of the first conductive layer 10 and the second shape of the second conductive layer 20 will be described.

[0153] exist Figure 10In the example shown, the positions of the plurality of protrusions 21 in the second shape do not correspond to the positions of the plurality of protrusions 11 in the first shape in a plane perpendicular to the Z direction (e.g., the XY plane). For example, in a cross-section parallel to the Z direction, the plurality of protrusions 21 in the second shape may include a protrusion 21u that at least partially overlaps with one of the plurality of protrusions 11 in the first shape in the Z direction, and a protrusion 21v that does not overlap with any of the plurality of protrusions 11. In this way, the positions of the protrusions in the first and second shapes do not correspond to each other in the XY plane, thereby preventing the application of large localized stress to the resin layer 30.

[0154] In addition, in the direction perpendicular to the Z direction (for example, the X direction), the position of the gap g between the first conductive layer 10 having the first shape and the resin layer 30 and the position of the gap g between the second conductive layer 20 having the second shape and the resin layer 30 may not correspond.

[0155] <Parameters Regarding the Cross-Sectional Shape of the Conductive Layer and the Surface Shape of the Resin Layer>

[0156] The electrode of this embodiment has a structure in which a particle layer is formed on a composite film. Therefore, it is difficult to directly analyze the shape of the conductive layer or resin layer across the entire XY plane of the composite film. Therefore, the inventors of this application discovered parameters that can be determined by observing a cross-section of the electrode parallel to the X direction and that can influence the electrode's properties, and investigated their relationship with the electrode's properties.

[0157] The method for observing the cross section of the electrode is not particularly limited. In this embodiment, a cross section parallel to the stacking direction (Z direction) of the electrode is observed using a scanning electron microscope (SEM).

[0158] In this specification, a cross section parallel to the Z direction and perpendicular to the Z direction (hereinafter referred to as the "width direction") DW having a length of a predetermined length L is referred to as a "unit cross section." The direction DW of the unit cross section may be parallel to the X direction or the Y direction, or may be a direction intersecting the X and Y directions. The length L may be 20 μm or greater. In this specification, the length L is set to 25 μm. It is preferred to prepare multiple observation samples using a single electrode with different width directions DW, and observe multiple unit cross sections.

[0159] Furthermore, below, for each parameter, specific examples of preferred numerical ranges in unit cross-sections that can be observed using a microscope such as an SEM are sometimes described. In this case, it is sufficient that the numerical value of the parameter obtained by observing at least one arbitrary unit cross-section is within the preferred range. The average value of the numerical value of the parameter in three or more unit cross-sections is preferably within a suitable range. The three or more unit cross-sections are preferably unit cross-sections with different width directions, for example, two unit cross-sections with mutually orthogonal width directions DW may be included. More preferably, the average value in five or more unit cross-sections is within a suitable range.

[0160] Below, refer to Figures 11 to 17 , the parameters used to optimize the electrode structure, such as the cross-sectional shape of the conductive layer in the electrode of this embodiment, the state of the interface between the conductive layer and the resin layer (including the position and shape of the gap), are described. The preferred ranges of the parameters for the first shape of the first conductive layer and the second shape of the second conductive layer can be the same, and the preferred ranges of the parameters for the first surface and the second surface of the resin layer can be the same. Therefore, below, the cross-sectional shape of the conductive layer is sometimes described using the first shape of the first conductive layer of the first electrode as an example, and the surface shape of the resin layer is sometimes described using the shape of the first surface of the resin layer as an example.

[0161] (a) Z direction

[0162] like Figure 2 As shown, when the second surface 32 of the resin layer 30 is substantially flat, the normal direction of the second surface 32 of the resin layer 30 in the cross-sectional microscope image such as the cross-sectional SEM image of the electrode becomes the "Z direction". Figure 10 As shown, when both the first surface 31 and the second surface 32 of the resin layer 30 have surface irregularities, it may be difficult to determine the “Z direction.” Therefore, an example of a method for determining the Z direction through cross-sectional observation will be described.

[0163] Figure 11 1 is a schematic cross-sectional view showing a portion of a unit cross section of the electrode 110A. Figure 11 As shown, in a unit cross section, a virtual reference plane 31S can be drawn for either the first surface 31 or the second surface 32 (here, the first surface 31), and the normal direction of the reference plane 31S can be set as the "Z direction." The reference plane 31S can be obtained using, for example, image analysis software such as "Azokun" (registered trademark) manufactured by Asahi Kasei Engineering Corp. For example, an average plane calculated from the contour of the first surface 31 of the resin layer 30 by analyzing an image of the unit cross section can be used as the reference plane 31S, and the normal direction of the average plane can be set as the Z direction.

[0164] Alternatively, the reference plane 31S may be a surface in which the total area of ​​an area 35 defined by the reference plane 31S and portions of the plurality of first surfaces 31 located above the reference plane 31S in a unit cross section is approximately the same as the total area of ​​an area 36 defined by the reference plane 31S and portions of the plurality of first surfaces 31 located below the reference plane 31S.

[0165] (b) Thickness T of the resin layer 30

[0166] Reference Figure 11 Next, the thickness T of the resin layer 30 will be described. The thickness T of the resin layer 30 can be obtained as, for example, the average distance between the second surface 32 and the first surface 31 of the resin layer 30 in the Z direction in a certain unit cross section.

[0167] In addition, in the tab area ( Figure 2 In the tab region 100t shown in FIG. 1 , when the first surface 31 and the second surface 32 of the resin layer 30 are substantially flat, the thickness of the resin layer 30 in the tab region can be measured and the thickness T can be approximately calculated. However, the thickness of the resin layer 30 in the tab region may be thicker than that in the region overlapping with the first material layer 111 ( Figure 2 The thickness T of the resin layer 30 in the illustrated region 100 e ) is large (eg, approximately 1 to 1.1 times).

[0168] The thickness T of the resin layer 30 is, for example, 3 μm or greater. A thickness T of 3 μm or greater can more effectively absorb stress applied to the conductive layer. Furthermore, strength as a current collector can be ensured. Preferably, the thickness T is 5 μm or greater. On the other hand, to improve energy density, the thickness T may be 12 μm or less, preferably 6 μm or less.

[0169] (c) Distance H

[0170] The distance H can be obtained as one of the parameters regarding the height difference in the Z direction of the first shape of the first conductive layer.

[0171] Figure 12 : is a schematic cross-sectional view showing a portion of a unit cross section of the first electrode 110. Figure 12As shown, in a certain unit cross section, the distances h1 to hn (n is an integer greater than or equal to 2) in the Z direction between the vertex 11a of each convex portion 11 and the bottom points 12b of the two concave portions 12 adjacent thereto on both sides can be obtained, and the maximum value h (max) of these distances can be set as "distance H". It is more preferable to obtain the maximum value h (max) of the distances h1 to hn for two or more unit cross sections, and set the average value thereof as "distance H". As described above, in this embodiment, the distance H is smaller than the thickness T of the resin layer 30. Thus, the stress of the first shape applied to the first conductive layer 10 can be alleviated by using the resin layer 30 of sufficient thickness, so that the reduction in the conductivity of the first conductive layer 10 can be suppressed. The distance H can also be less than 1 / 2 of the thickness T of the resin layer 30.

[0172] On the other hand, the distance H may be, for example, more than 1 / 10 of the thickness t of the first conductive layer 10. Alternatively, the distance H may be more than 0.2 μm. Thus, a more effective stress relief effect can be obtained. In addition, although it also depends on the size of the particles in the particle layer, since it is easy to bear the particles in the first shape, the local stress caused by the particles can be relieved. The "thickness t of the first conductive layer" is, for example, the average value of the distance in the Z direction between the outer surface and the inner surface of the first conductive layer 10 in each unit cross section. Alternatively, in the tab region ( Figure 2 When the tab region 100 t shown is a flat region, the thickness of the first conductive layer 10 in the tab region may be measured as the thickness t.

[0173] Furthermore, when the first conductive layer 10 has a corrugated shape in the cross-sectional view, the amplitude Am of the corrugated shape can also be determined from the unit cross section. The amplitude Am is determined, for example, as 1 / 2 of the distance H. Alternatively, as described above, the amplitude Am can be determined using pixel analysis software.

[0174] In this embodiment, the amplitude Am is smaller than the thickness T of the resin layer 30. This effectively reduces the stress applied to the first conductive layer 10 from the first material layer 111. When the first conductive layer 10 and the second conductive layer 20 have a corrugated shape in cross-sectional view, the amplitude Am of the corrugated shape of each conductive layer may be smaller than the thickness T.

[0175] In addition, if Figure 10 As shown, when the first conductive layer 10 and the second conductive layer 20 located on both sides of the resin layer 30 each have a cross-sectional shape including a plurality of convex portions, the distance H between the first conductive layer 10 and the second conductive layer 20 is preferably less than the thickness T, and more preferably less than 1 / 2 of the thickness T. This can more reliably prevent the concave regions formed on both sides of the resin layer 30 from connecting to each other. Consequently, a decrease in conductivity caused by deformation of the electrode can be suppressed.

[0176] (d) convex portion height d1, concave portion depth d2, distance dm1, distance dm2

[0177] As parameters for the size of the concave and convex portions in the first shape, for example, the distance dm1 and / or the distance dm2 described below are used. The distance dm1 corresponds to the average value of the height d1 of the convex portions included in each unit cross section (also referred to as "convex portion height"), and the distance dm2 corresponds to the average value of the depth d2 of the concave portions 12 included in each unit cross section (also referred to as "concave portion depth")

[0178] Figure 13 This is a diagram showing a portion of the cross section of the first electrode, and is a schematic diagram based on a cross-sectional SEM image. Figure 14 It is a schematic diagram showing a part of a unit cross section of the first electrode.

[0179] The height d1 of the convex portion can be measured, for example, as follows. Figure 13 and Figure 14 As shown, first, in a unit cross section, a line (line segment) f1 is drawn connecting the bottom point of a concave portion 12n1 located on the -DW side of a convex portion 11n to be measured on the inner surface of the first conductive layer 10 and the bottom point of a concave portion 12n2 located on the +DW side of the convex portion 11n. In this example, line f1 is a tangent to the two concave portions. Next, the distance between line f1 and the convex portion 11n is measured in a direction perpendicular to line f1. The distance d1 between line f1 and the point n1 on the convex portion 11n that is farthest from line f1 in the vertical direction is defined as the "convex portion height." Point n1 can be, for example, the vertex of the convex portion 11n.

[0180] Likewise, the recess depth d2 can be measured as follows. Figure 13 and Figure 14 As shown, first, within a unit cross section, a line f2 is drawn connecting the vertex of a convex portion 11m1 located on the -DW side of a concave portion 12m to be measured, with the vertex of a convex portion 11m2 located on the +DWX side of concave portion 12m, on the inner surface of the first conductive layer 10. In this example, line F2 is a tangent to these two convex portions. Next, the distance between line f2 and concave portion 12m is measured perpendicular to line f2. The distance d2 between line f2 and point m1, the point in concave portion 12m most vertically distant from line f2, is defined as the "concave depth." Point m1 can be, for example, the bottom of concave portion 12.

[0181] In this embodiment, the convex portion height d1 is measured for each convex portion 11 included in one or more unit cross sections, and the average value thereof is set as the distance dm1. In addition, the concave portion depth d2 is measured for each concave portion 12 included in one or more unit cross sections, and the average value thereof is set as the distance dm2. When calculating the distance dm1 and the distance dm2, the convex portion height d1 and the concave portion depth d2 measured by the above method do not include, for example, values ​​less than 0.1 μm (or less than 1 / 10 of the thickness of the first conductive layer 10). Thus, the fine concave and convex of the first conductive layer 10 can be ignored, and the average of the concave and convex that can make a greater contribution to stress relaxation can be calculated. In addition, in this embodiment, as a parameter of the size of the concave and convex, at least one of the distance m1 and the distance m2 can be calculated.

[0182] The average value of the distance dm1 is, for example, greater than or equal to 0.1 μm and less than or equal to 3.0 μm. Similarly, the distance dm2 is, for example, greater than or equal to 0.1 μm and less than or equal to 3.0 μm. If the distance dm1 and / or the distance dm2 is greater than or equal to 0.1 μm, the stress applied to the first conductive layer 10 from the first material layer 111 can be more effectively alleviated. The distance dm1 and / or the distance dm2 are preferably greater than or equal to 0.2 μm. On the other hand, if the distance dm1 and / or the distance dm2 is less than or equal to 3.0 μm, deformation of the electrode and increase in resistance of the first conductive layer 10 caused by significant local deformation of the first conductive layer 10 can be suppressed.

[0183] Furthermore, the maximum value of the height d1 of the convex portion 11 included in one or more unit cross sections can be, for example, 0.2 μm or more and 3.0 μm or less. Similarly, the maximum value of the depth d2 of the concave portion 12 included in one or more unit cross sections can be, for example, 0.2 μm or more and 3.0 μm or less. This can suppress deformation of the electrode and more effectively alleviate the stress applied to the first conductive layer 10 from the first material layer 111.

[0184] (e) Determination of convex and concave parts

[0185] When comparing and studying the first shape, it is preferable to remove fine concavities and convexities formed on the inner surface of the first conductive layer in a unit cross section. For example, the above-mentioned method of measuring the height d1 of the convex portion can be used to remove the fine concavities and convexities. Figure 15 The method is described.

[0186] Figure 15 This is a diagram showing a portion of a cross-sectional SEM image of an electrode produced in the examples described later, and shows an example of a unit cross section of the width (length) L of the electrode. Figure 15 As shown in FIG. 1 , convex portions a1 to a10 that are convexly bent toward the +Z side are selected from the first conductive layer 10. Next, the selected convex portions a1 to a10 are subjected to the Figure 13 and Figure 14 The height d1 of the convex portion is calculated using the method shown. Next, the relationship between the height d1 of the convex portions a1 to a10 and a predetermined distance (e.g., 0.1 μm) is examined. Only those convex portions a1 to a10 whose height d1 exceeds the predetermined distance are designated as "convex portions 11." The predetermined distance is not limited to 0.1 μm and can be, for example, 1 / 10 of the thickness t of the first conductive layer 10.

[0187] exist Figure 15 In the example shown, among the convex portions a1-a10, convex portions a1-a5, a7, a8, and a10, whose height d1 is greater than 0.1 μm, constitute the convex portions 11 of the first conductive layer 10. Convex portions a6 and a9 are fine convex portions with a height d1 less than 0.1 μm and are therefore not included in the convex portion. Similarly, for the concave portion 12, a concave portion having a depth d2 greater than the predetermined distance described above can be selected as the concave portion 12.

[0188] Furthermore, when the boundary between the convex portion 11 and the concave portion 12 is required, it can also be Figure 3 As described above, on the inner surface 10b of the first conductive layer 10, an inflection point between the apex of the convex portion 11 and the bottom of the concave portion 12 is obtained, and a line 15 passing through the inflection point and parallel to the Z direction is used as a boundary line. Figure 15 In FIG. 1 , the apex 11 a of the convex portion 11 is represented by a black circle, and the bottom 12 b of the concave portion 12 is represented by a hollow rhombus.

[0189] (f) Number Na of convex portions 11, number Nb of concave portions 12, and number of concave regions 312

[0190] Reference Figure 15 , the number of convex portions 11, concave portions 12 and concave areas 312 in a unit cross section is described. The density (or arrangement pitch) of the convex portions in the first conductive layer is also considered to be one of the parameters, but it is difficult to measure the density from a cross section. Therefore, the number Na of convex portions in a unit cross section can also be used as a parameter instead of the density of the convex portions 11 in the first shape. The arrangement pitch of the convex portions can also be calculated based on the relationship between the number Na of convex portions in a unit cross section and the length (width) L of the unit cross section. The number Nb of concave portions can also be used instead of the number Na of convex portions.

[0191] The number Na of protrusions 11 in a unit cross section is, for example, not less than 2 and not more than 10. If it is not less than 2, for example, the stress applied to the first conductive layer 10 from the first material layer 111 can be more effectively reduced. If it exceeds 10, the width of the protrusion 11 becomes smaller than the particles of the first material layer 111, and sometimes it is difficult to receive the particles. Although it also depends on the size of the particles of the first material layer 111, if the number Na of protrusions 11 is, for example, not less than 2 and not more than 10, the interval between adjacent recesses 12 becomes a size that can easily receive the particles of the first material layer 111, so that the deformation of the electrode caused by the expansion and contraction of the first material layer 111 can be suppressed. Figure 15 In the unit cross section shown, the number Na of protrusions 11 of the first conductive layer 10 is 5, and the number Na of protrusions 21 of the second conductive layer 20 is 3. The "number Na of protrusions" here refers to the number of protrusions with a height d1 of 0.1 μm or greater, and does not include protrusions that are significantly smaller than the thickness of the first conductive layer 10.

[0192] The number Nb of the recesses 12 per unit cross section may be obtained instead of the number Na of the protrusions 11. The number Nb of the recesses 12 is similar to the number Na of the protrusions 11, and is, for example, 2 or more and 10 or less.

[0193] The number of concave regions 312 on the first surface 31 of the resin layer 30 per unit cross-section is, for example, the same as or smaller than the number of convex portions 11. This is because the concave regions 312 may not be able to follow the deformation of the first conductive layer 10 toward the resin layer. Therefore, the number of concave regions 312 is, for example, one or more and ten or less.

[0194] (g) Ratio Lm / L of the length Lm of the inner surface 10b of the first conductive layer 10

[0195] Reference Figure 15 , the ratio Lm / L of the length Lm of the inner surface 10b of the first conductive layer 10 is described. In a unit cross section, the ratio Lm / L of the length Lm of the inner surface 10b of the first conductive layer 10 to the length L (here, 2.5 μm) can be used as a parameter indicating the degree of meandering of the first conductive layer 10. As described later, when the substantially flat first conductive layer 10 is deformed into the first shape by pressure during formation of the first material layer 111, the ratio Lm / L of the length Lm can be said to represent the elongation of the first conductive layer 10 in the width direction DW.

[0196] The length Lm of the inner surface 10b of the first conductive layer 10 can be calculated by analyzing the unit cross section.

[0197] The ratio Lm / L is, for example, 1.04 or greater and 1.20 or less. If it is 1.04 or greater, the stress applied to the first conductive layer 10 from the first material layer 111 can be more effectively alleviated. If it is 1.20 or less, an increase in the resistance of the first conductive layer 10 caused by elongation and thinning of the first conductive layer 10 can be suppressed.

[0198] (h) Thickness of the first conductive layer 10

[0199] Reference Figure 15 The thickness t of the first conductive layer 10 will be described. In a unit cross section, the thickness t of the first conductive layer 10 in the Z direction is, for example, 0.3 μm or more and 1.5 μm or less. The thickness t is the average distance in the Z direction between the inner surface 10 b and the outer surface 10 a of the first conductive layer 10.

[0200] If the thickness t is 0.3 μm or greater, the resistance of the first conductive layer 10 can be suppressed to a low level. If the first conductive layer 10 is too thick, deformation becomes difficult, and the effect of relieving stress from the first material layer 111 through deformation of the first conductive layer 10 and the resin layer 30 becomes less. If the thickness of the first conductive layer 10 is, for example, 1.5 μm or less, deformation of the first conductive layer 10 becomes easy, and the effect of relieving stress from the first material layer 111 through deformation of the first conductive layer 10 and the resin layer 30 becomes more significant. Furthermore, the overall composite film 100 can be made thinner and lighter.

[0201] The thickness t of the first conductive layer 10 may be thinner at the convex portion 11 than at the concave portion 12. Figure 15 As illustrated, for example, in a unit cross-section, the thinnest portion t1min of the first conductive layer 10 can be located at any one of the plurality of protrusions 11. Similarly, the thinnest portion t2min of the second conductive layer 20 can be located at any one of the plurality of protrusions 21. The thinnest portions t1min and t2min of the first conductive layer 10 and the second conductive layer 20 are preferably 0.3 μm or greater, or at least half of the thickness tm. This can suppress a decrease in the conductivity of the conductive layer.

[0202] (i) Size and shape of gap g

[0203] Figure 16 This is a diagram showing a portion of the cross section of the first electrode 110A, and is a schematic diagram based on a cross-sectional SEM image. Figure 17 It is a schematic cross-sectional view showing a part of the cross section of the first electrode 110A.

[0204] like Figure 16 and Figure 17As shown in the example, as parameters representing the size of each gap g in the unit cross section, the maximum distance (height) hg of the gap g in the Z direction and the maximum length (width) wg of the gap g in the width direction DW can be used. In addition, as a parameter representing the cross-sectional shape of the gap g, the ratio hg / wg of the height hg to the width wg can also be used. Figure 16 In the example shown, the perimeter (outline) of gap g is defined by the first surface of resin layer 30 and the inner surface of first conductive layer 10. In other words, gap g is surrounded by the first surface of resin layer 30 and the inner surface of first conductive layer 10. In this case, the height hg of gap g corresponds to the peeling distance between resin layer 30 and first conductive layer 10 in the Z direction, and the width wg of gap g corresponds to the peeling distance between resin layer 30 and first conductive layer 10 in the width direction DW.

[0205] The average value of the height hg of the one or more gaps g located between the first conductive layer 10 and the resin layer 30 per unit cross-section is, for example, greater than 0 and not more than 3 μm. When the height hg is 3 μm or less, the first conductive layer 10 can be more reliably supported by the resin layer 30, thereby suppressing a decrease in conductivity caused by damage or bending in portions of the first conductive layer 10 away from the resin layer 30. Similarly, the average value of the height hg of the one or more gaps g located between the second conductive layer 20 and the resin layer 30 is also, for example, greater than 0 and not more than 3 μm.

[0206] Furthermore, in a unit cross-section, the average value of the ratio hg / wg of the height hg to the width wg of the one or more gaps g located between the first conductive layer 10 and the resin layer 30 is, for example, greater than 1 and less than 20. If this ratio is greater than 1, the internal stress of the first conductive layer 10 can be more effectively alleviated by the gaps g. If this ratio is less than 20, the first conductive layer 10 can be more reliably supported by the resin layer 30. Therefore, the stress applied to the first conductive layer 10 can be more easily alleviated by the resin layer 30. Similarly, the average value of the ratio hg / wg of the one or more gaps g located between the second conductive layer 20 and the resin layer 30 is also, for example, greater than 1 and less than 20.

[0207] (j) Ratio of gap g

[0208] Reference Figure 17 The ratio of the gap g will be described. From the perspective of stress relaxation in the first conductive layer 10, the ratio of the gaps in the composite film 100A, such as the number density when viewed from the Z direction and the area ratio of the gaps, is preferably greater than or equal to a predetermined value. In this embodiment, the number Ng of recesses 12 in the first conductive layer 10 that overlap with the gap g in the Z direction is used as a parameter in place of the number density of the gaps.

[0209] Alternatively, the first conductive layer 10 may have one or more recesses 12 per unit cross-section, and the number Ng of recesses 12 that at least partially overlap with the gap g in the Z direction may be, for example, one or more and ten or less. If the number Ng is one or more, the internal stress of the first conductive layer 10 can be more effectively alleviated. If the number Ng is ten or less, the first conductive layer 10 can be more reliably supported by the resin layer 30, and thus the stress applied to the first conductive layer 10 can be absorbed by deformation of the resin layer 30. The number of gaps g is not particularly limited and may be three or more and ten or less.

[0210] In addition, if Figure 17 As illustrated, in the example where the first conductive layer 10 and the resin layer 30 are partially in contact (i.e., no other layer is interposed between the first conductive layer 10 and the resin layer 30), the number Ng of recesses 12 described above refers to the number Ng of recesses 12 in contact with the gap g. "Recesses in contact with the gap" include recesses 12 where part or all of the recesses 12 are separated from the first surface 31 of the resin layer 30, forming a gap g between the first surface 31 and the recesses 12.

[0211] exist Figure 17 In the example shown, two gaps g are provided between the first conductive layer 10 and the resin layer 30. In this example, the number Ng of recesses 12 in the first conductive layer 10 that contact the gaps g is three, and the number Ng of recesses 22 in the second conductive layer 20 that contact the gaps g is one.

[0212] Alternatively, as a parameter replacing the area ratio of the gap g, the ratio Tw / L of the total widths Tw of the width wg of one or more gaps g included in the unit cross section in the width direction DW to the length L of the unit cross section can be used. Alternatively, the ratio LX / L of the total length LX of the first portion 10X in contact with the gap g in the first conductive layer 10 to the length L of the unit cross section can be used. The total length LX is the total length of the one or more first portions 10X included in the unit cross section in the width direction DW.

[0213] The ratio Tw / L and the ratio LX / L are both, for example, 0.02 or greater and 0.5 or less. If 0.02 or greater, the internal stress of the first conductive layer 10 can be more effectively alleviated. If 0.5 or less, the first conductive layer 10 can be more reliably supported by the resin layer 30, so that the stress applied to the first conductive layer 10 can be absorbed by the deformation of the resin layer 30. Tw / L can be 0.2 or greater and 0.5 or less.

[0214] [Effect]

[0215] In conventional electrodes, for example, during the process of forming a particle layer on a conductive film (e.g., a calendering process), the expansion and contraction of the particle layer during operation of the energy storage device can locally exert large stress on the conductive film, potentially reducing the conductivity of the conductive film. In contrast, according to this embodiment, since the particle layer is formed on a conductive layer supported by a resin layer, at least a portion of the pressure caused by the particles during formation of the particle layer can be absorbed by the deformation of the conductive layer and the resin layer. Furthermore, in an energy storage device using the electrode of this embodiment, the conductive layer and the resin layer having the first shape (or second shape) can absorb the stress applied to the conductive layer due to the expansion and contraction of the particle layer during operation of the energy storage device. Since the particles of the particle layer can be received by the convex portion of the conductive layer that curves toward the resin layer, the application of large local stress to the conductive layer can be suppressed. Consequently, degradation of the electrode, such as a reduction in the conductivity of the conductive layer, can be suppressed.

[0216] Furthermore, by partially providing a gap between the conductive layer and the resin layer, the internal stress generated when the conductive layer is formed can be alleviated, thereby suppressing a decrease in the conductivity of the electrode caused by the internal stress of the conductive layer.

[0217] Therefore, by using the electrode of this embodiment in the positive electrode or negative electrode of a power storage device such as a secondary battery, the rate characteristics of the power storage device can be improved, and the reliability of the power storage device can also be improved.

[0218] [Method for manufacturing electrode]

[0219] The manufacturing method of the electrode of this embodiment includes, for example: a process of preparing a laminated film having a resin layer and a conductive layer supported by the resin layer (step 1); a process of deforming the conductive layer supported by the resin layer into a prescribed shape (step 2); and a process of forming a material layer (here a granular layer) on the conductive layer supported by the resin layer (step 3).

[0220] Step 2 and step 3 may also be performed simultaneously. For example, when a particle layer comprising a plurality of particles is formed on the conductive layer, under specified conditions, the plurality of particles press the conductive layer, thereby enabling the portions of the conductive layer pressed by the particles to bend into a convex shape toward the resin layer side. It is believed that this is because when the particles press the conductive layer, a local force is applied to the conductive layer in the depth direction, and the local force is absorbed by the local deformation of the conductive layer and the resin layer, thereby causing the conductive layer to plastically deform. The conductive layer after forming the particle layer, for example, has a first shape (or second shape) comprising convex portions corresponding to these particles. At this time, the surface of the resin layer may also deform as the conductive layer deforms. For example, a concave area may be formed on the surface of the resin layer in a manner that supports the convex portions of the conductive layer. In the event that the resin layer cannot adequately follow the deformation of the conductive layer, a gap may be generated in a portion between the conductive layer and the resin layer surface.

[0221] The shape of the conductive layer and the surface shape of the resin layer are formed by adjusting various conditions. Examples of conditions for adjusting the shape of the conductive layer include the hardness and thickness of the resin layer, the type of conductive layer (ductility, thickness, the type of particles in the granular layer, the form of powder used as the granular layer, the shape and size of the particles after forming the granular layer (after pressurization), the pressurization conditions and temperature conditions when forming the granular layer, etc.). By adjusting these conditions, a conductive layer having a predetermined shape can be achieved.

[0222] The type, thickness, main formation method, etc. of each layer will be described later. When a calendering treatment or other pressurization is performed when forming the particle layer, as the pressurization conditions, for example, when the conductive layer is an aluminum layer, the linear pressure can be set within the range of 5000N / cm to 30000N / cm and the conveying speed can be set within the range of 5m / min to 30m / min. When the conductive layer is a copper layer, the linear pressure can be set within the range of 600N / cm to 35000N / cm and the conveying speed can be set within the range of 5m / min to 30m / min. The pressurization of the particle layer can be performed at room temperature or at a temperature of, for example, 30°C to 80°C (hot pressing). By performing hot pressing, the conductive layer and the resin layer can be easily deformed.

[0223] Among them, in the prior art, emphasis is placed on suppressing the deterioration caused by the deformation of the current collector during the calendering process, and the material, thickness, and formation conditions of the particle layer of each layer are selected. The same applies to the case of using a composite film as a current collector, and it is considered that manufacturing conditions that intentionally deform the conductive layer should not be selected. In contrast, in this embodiment, the material, thickness, and formation conditions of the particle layer of each layer are set under conditions that intentionally deform the conductive layer and the resin layer into a specified shape. In addition, conditions that intentionally create gaps inside the electrode are sometimes set. These conditions are interrelated. For example, if the thickness of the conductive layer is different, the appropriate pressurization conditions will be different.

[0224] by Figure 2 The method for manufacturing the electrode according to this embodiment will be described in more detail by taking the first electrode 110A shown as an example.

[0225] First, a laminated film including a resin layer 30, a first conductive layer 10, and a second conductive layer 20 is prepared. Here, the first conductive layer 10 is formed on the first surface 31 of the resin layer 30, and the second conductive layer 20 is formed on the second surface 32 of the resin layer 30, thereby obtaining a laminated film. The method for forming the first conductive layer 10 and the second conductive layer 20 is not particularly limited, and for example, evaporation, sputtering, electroplating, electroless plating, etc. may be used. Alternatively, metal foils forming the first conductive layer 10 and the second conductive layer 20 may be bonded to the first surface 31 and the second surface 32 of the resin layer 30, respectively.

[0226] For example, a polyethylene terephthalate film is used as the resin layer 30. The surface of the resin layer 30 may be substantially flat. Alternatively, the surface may have surface irregularities for the purpose of improving adhesion, etc.

[0227] When the first electrode 110A is, for example, the positive electrode of a lithium-ion secondary battery, an aluminum film is used as the first conductive layer 10 and the second conductive layer 20. The aluminum film can be formed on both sides of the resin layer 30 by vapor deposition or the like. When the first electrode 110A is the negative electrode, a copper film can be used as the first conductive layer 10 and the second conductive layer 20. For example, a nickel-chromium (NiCr) or copper seed layer can be formed on both sides of the resin layer 30 by sputtering, and then a copper film can be formed on the seed layer by electrolytic plating. In this way, a laminated film serving as a precursor to a composite film is obtained.

[0228] Figure 18 : is a diagram showing the cross-sectional shape of a portion of the laminated film obtained by the above method, and is a schematic diagram based on a cross-sectional SEM image. Figure 18 As shown in the example, at this point, the first conductive layer 10 and the second conductive layer 20 of the laminate film 100B do not need to have curved portions. In this example, the upper surface of the laminate film (here, the outer surface 10a of the first conductive layer 10) and the lower surface of the laminate film (here, the outer surface 20a of the second conductive layer 20) are substantially flat. Furthermore, each conductive layer may have irregularities reflecting the surface shape of the resin layer 30.

[0229] Afterwards, a first material layer 111 as a particle layer is formed on the upper surface of the laminate film, and a second material layer 112 as a particle layer is formed on the lower surface of the laminate film. Specifically, first, a slurry containing an active substance, a binder and a solvent is prepared, and the slurry is applied to the upper and lower surfaces of the laminate film, respectively. The solvent can be an organic solvent such as methanol, ethanol, propanol, N-methyl-2-pyrrolidone, N,N-dimethylformamide, or water. The slurry can be applied by a doctor blade coater, a slit die coater, a rod coater, etc. Alternatively, screen printing or gravure printing can be used in the application of the slurry. At this time, the slurry is not applied to the entire surface of the laminate film, and an area to which the slurry is not applied remains. After the slurry is applied to the laminate film, the solvent in the slurry is removed by drying.

[0230] After the slurry layer is dried, the slurry layer is pressurized by a roller press device or the like. As described above, by appropriately setting the pressure, temperature and other conditions during pressurization, the first conductive layer 10 and the second conductive layer 20 in the laminate film are bent. Here, the portion of the first conductive layer 10 located between the resin layer 30 and the first material layer 111 is bent by pressurization and deformed into a first shape. Similarly, the portion of the second conductive layer 20 located between the resin layer 30 and the second material layer 112 is bent by pressurization and deformed into a second shape. In this way, the first conductive layer 10 and the second conductive layer 20 are deformed, and the first material layer 111 is formed on the first conductive layer 10, and the second material layer 112 is formed on the second conductive layer 20. Among them, the areas in the first conductive layer 10 and the second conductive layer 20 to which the slurry is not applied can also be bent without pressurization. Such areas can also have a roughly flat surface after pressurization.

[0231] Then, the laminated film, the first material layer 111, and the second material layer 112 are cut into a predetermined shape including an area not provided with slurry, thereby obtaining a first electrode 110A having the composite film 100 and the material layers 111 and 112 provided on both sides of the composite film 100. The area of ​​the laminated film not provided with slurry becomes the tab region 100t of the composite film 100A.

[0232] The cross section of the first electrode 110A manufactured by the above method and before being assembled into a single cell (i.e. before charging and discharging) was observed using SEM. Figure 18 The laminated film 100B shown is different in that the first conductive layer 10 and the second conductive layer 20 are curved. That is, it was confirmed that the first conductive layer 10 and the second conductive layer 20 can be deformed into a predetermined shape by the pressure applied when forming the material layer (granular layer) according to the above method.

[0233] Furthermore, while the above description shows an example in which the step of deforming the conductive layer (step 2) is performed simultaneously with the step of forming the particle layer (step 3), the step of deforming the conductive layer may also be performed separately. For example, after forming the conductive layer on the surface of the resin layer, the laminated film comprising the conductive layer and the resin layer may be processed to deform the conductive layer into the first shape (or second shape). Subsequently, the particle layer may be formed on the deformed conductive layer.

[0234] [Structure of the power storage device]

[0235] Next, an example of the configuration of an electricity storage device using the electrode of this embodiment will be described using a lithium-ion secondary battery as an example.

[0236] Figure 19 is a schematic external view showing an example of the structure of an electricity storage device. Figure 20 It will Figure 19 An exploded perspective view of a battery cell removed from the illustrated energy storage device. Here, a pouch-type or laminate-type lithium-ion secondary battery is illustrated as an example of an energy storage device. The illustrated lithium-ion secondary battery is a single-layer battery, but a stacked type is also possible, as described later. In the illustrated example, the positive electrode, separator, and negative electrode that constitute the battery cell are stacked along the Z direction of the diagram.

[0237] like Figure 19 As shown, lithium-ion secondary battery 1001 includes: a unit cell 2001 ; a pair of leads 250 and 260 connected to unit cell 2001 ; an exterior body 300 covering unit cell 2001 ; and an electrolyte 290 .

[0238] Cell 2001 includes a first electrode 110, a second electrode 120, and a first layer 170 disposed between the first and second electrodes 110, 120. For example, first electrode 110 is a positive electrode, and second electrode 120 is a negative electrode. First layer 170, for example, comprises an insulating material and functions as a separator. In the illustrated example, cell 2001 is a single-layer cell comprising a pair of electrodes.

[0239] Lead 250 is electrically connected to the first electrode 110 of cell 2001, and lead 260 is electrically connected to the second electrode 120 of cell 2001. In this example, within the exterior body 300, lead 250 is connected to the tab region 100t of the composite film 100 of the first electrode 110, and lead 260 is connected to the tab region 200t of the composite film 200 of the second electrode 120. A portion of lead 250 and a portion of lead 260 may also be located outside the exterior body 300. The portion of lead 250 extending outside the exterior body 300 functions as the first terminal (here, the positive terminal) of the lithium-ion secondary battery 1001 of the energy storage device. The portion of lead 260 extending outside the exterior body 300 functions as the second terminal (here, the negative terminal) of the lithium-ion secondary battery 1001.

[0240] An electrolyte 290 is further disposed in the space inside the outer body 300. The electrolyte 290 is, for example, a non-aqueous electrolyte. When a non-aqueous electrolyte is used as the electrolyte 290, a sealing material (e.g., a resin film such as polypropylene, etc.) for preventing leakage of the electrolyte can typically be disposed between the outer body 300 and the lead 250, and between the outer body 300 and the lead 260. Figure 19 (not shown in the figure).

[0241] The first electrode 110 has a reference Figure 1 and Figure 2 The structure described. Figure 20 As shown, the second electrode 120 includes a composite film 200 in the same manner as the first electrode 110. The second electrode 120 includes a composite film 200 and a first material layer 211 located on the composite film 200. The first electrode 110 and the second electrode 120 are arranged in a manner such that the first material layer 111 and the first material layer 211 are opposite to each other with the first layer 170 interposed therebetween. In the example shown in the figure, the first material layer 211 is arranged only on a portion of the composite film 200. The first material layer 211 functions as an active material layer, for example. The composite film 200 includes a tab region 200t located outside the first material layer 211 in the Z direction (not overlapping with the first material layer 211). In addition, here, an example of applying a composite film 200 that can function as a current collector to the second electrode 120 is shown, but the second electrode 120 may also be a metal current collector such as a metal foil.

[0242] The second electrode 120 may have the same structure as the first electrode 110. That is, the first material layer 211 of the second electrode 120 is a particle layer containing a plurality of particles, and the conductive layer of the composite film 200 may also have the first shape in a cross section parallel to the Z direction. In addition, in the second electrode 120, the first material layer 211 may not be a particle layer. In addition, in a cross section parallel to the Z direction, the conductive layer of the composite film 200 may not have the first shape or the second shape. For example, the second electrode 120 may have an inner surface and an outer surface that are substantially flat. Furthermore, the second electrode 120 may not have a composite film. In this case, the second electrode 120 may also have a metal foil that functions as a current collector and a material layer located on the metal foil.

[0243] [Structural Example 2 of Electricity Storage Device]

[0244] Figure 21 is a schematic external view showing another example of the structure of an electricity storage device. Figure 22 It will Figure 21 The exploded perspective view of the battery device shown in FIG. 1 is a battery device with a single cell removed. Here, a stacked lithium-ion secondary battery is shown as an example of a battery device. Figure 19 and Figure 20 The same components of the lithium-ion secondary battery 1001 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

[0245] like Figure 21 As shown, lithium-ion secondary battery 1002 includes: a unit cell 2002 ; a pair of leads 250 and 260 connected to unit cell 2002 ; an exterior body 300 covering unit cell 2002 ; and an electrolyte 290 .

[0246] like Figure 22 As shown, the cell 2002 includes one or more first electrodes 110A, one or more second electrodes 120A, and one or more first layers 170A. Figure 22 In the illustrated structure, the first electrode 110A, the second electrode 120A, and the first layer 170A are all in sheet form. Figure 22 In the example shown, the first electrode 110A, the second electrode 120A, and the first layer 170A are stacked along the Z direction in the figure.

[0247] like Figure 22As schematically shown, cell 2002 has a structure in which first electrodes 110A and second electrodes 120A are alternately stacked with first layers 170A interposed therebetween. For example, first electrode 110A is a positive electrode, and second electrode 120A is a negative electrode. Cell 2002 includes, for example, 19 first electrodes 110A and 20 second electrodes 120A. In this case, cell 2002 includes a total of 19 first layers 170A, each positioned between first electrodes 110A and second electrodes 120A.

[0248] Each first electrode 110A may have a reference Figure 9 and Figure 10 The above structure. Figure 22 As shown, each second electrode 120A includes a composite film 200A, similar to the first electrode 110A. The second electrode 120A includes the composite film 200A, a first material layer 211 located on the upper surface of the composite film 200A, and a second material layer 212 located on the lower surface of the composite film 200A. The first material layer 211 and the second material layer 212 function as active material layers, for example. The composite film 200A includes a tab region 200At located outside the first material layer 211 and the second material layer 212 in the XY plane (and not overlapping with the first material layer 211 and the second material layer 212 in the Z direction).

[0249] The structure of each second electrode 120A can be the same as or different from that of the first electrode 110A. Specifically, the first material layer 211 and the second material layer 212 of the second electrode 120A are granular layers containing a plurality of particles. In a cross section parallel to the Z direction, the first conductive layer of the composite film 200A can have a first shape, and the second conductive layer can have a second shape. The first material layer 211 and the second material layer 212 of the second electrode 120A can be non-granular layers. Furthermore, in a cross section parallel to the Z direction, the first conductive layer and the second conductive layer of the composite film 200A can have no curved protrusions and, for example, can have substantially flat inner and outer surfaces. Furthermore, when a composite film is not used for the second electrode 120A, the second electrode 120A can also include a metal foil functioning as a current collector and material layers located on either side of the metal foil.

[0250] The first layer 170A is disposed between the first electrode 110A and the second electrode 120A located closest to the first electrode 110A. The first layer 170A is formed of an insulating material such as resin to prevent direct contact between the particle layers of the first electrode 110A and the second electrode 120A.

[0251] exist Figure 22 In the example shown, the lead wire 250 is electrically connected to the plurality of first electrodes 110A, and the lead wire 260 is electrically connected to the plurality of second electrodes 120A.

[0252] like Figure 22 As shown, the second electrode 120A located at the top of the stacked structure of the first electrode 110A and the second electrode 120A among the plurality of second electrodes 120A may or may not have the first material layer 211 on its top surface. Similarly, the second electrode 120A located at the bottom of the stacked structure of the first electrode 110A and the second electrode 120A among the plurality of second electrodes 120A may or may not have the second material layer 212 on its bottom surface.

[0253] Furthermore, the electricity storage device to which the electrode of this embodiment can be applied is not limited to lithium-ion secondary batteries, but can also be applied to, for example, electric double layer capacitors.

[0254] [Description of components]

[0255] Below, Figure 21 The lithium ion secondary battery 1002 and Figure 22 The components of the power storage device of this embodiment will be described in more detail by taking the illustrated single cell 2002 as an example.

[0256] In the lithium-ion secondary battery 1002, one of the first electrode 110A and the second electrode 120A is a positive electrode, and the other is a negative electrode. The positive electrode and the negative electrode can each include a composite film having a conductive layer provided on the surface of a resin layer, and a material layer supported by the composite film. In the following description, the composite film used for the positive electrode is referred to as the "positive electrode composite film," the resin layer of the positive electrode composite film is referred to as the "positive electrode resin layer," the conductive layers (first and second conductive layers) of the positive electrode composite film are referred to as the "positive electrode conductive layer," and the material layer of the positive electrode is referred to as the "positive electrode material layer." Similarly, the composite film used for the negative electrode is referred to as the "negative electrode composite film," the resin layer of the negative electrode composite film is referred to as the "negative electrode resin layer," the conductive layers (first and second conductive layers) of the negative electrode composite film are referred to as the "negative electrode conductive layer," and the particle layer of the negative electrode is referred to as the "negative electrode material layer."

[0257] (Positive electrode composite membrane)

[0258] Positive electrode resin layer

[0259] The positive electrode resin layer of the positive electrode composite film is, for example, a sheet with a thermoplastic resin as the matrix. As the matrix of the positive electrode resin layer, polyester resins, polyamide resins, polyethylene resins, polypropylene resins, polyolefin resins, polystyrene resins, phenolic resins, polyurethane resins, acetal resins, cellophane and ethylene-vinyl alcohol copolymer (EVOH), polyethylene terephthalate, polystyrene (PS), polyimide and polyvinyl chloride can be used. Examples of polyolefin resins are polyethylene (PE) and polypropylene (PP). Polyolefin resins can be acid-modified polyolefin resins. Examples of polyester resins are polybutylene terephthalate (PBT) and polyethylene naphthalate. Examples of polyamide resins are nylon 6, nylon 66 and poly(m-xylene adipamide) (MXD6). For example, a uniaxially stretched sheet or a biaxially stretched sheet of polyethylene terephthalate or a biaxially stretched sheet of polypropylene can be suitable for the positive electrode resin layer. In the present embodiment, the resin layer 30 may include, for example, at least one of polyethylene terephthalate, polypropylene, polyamide, polyimide, polyethylene, polystyrene, phenolic resin, and epoxy resin.

[0260] The base material of the positive electrode resin layer can also be the same material as that of the separator. The positive electrode resin layer can be provided as a laminated film comprising two or more of the above materials. The positive electrode resin layer can further contain a fireproofing agent, etc.

[0261] The thickness of the positive electrode resin layer is, for example, 3 μm or more and 12 μm or less. The positive electrode resin layer is not limited to a resin film. The positive electrode resin layer may be a nonwoven fabric or a porous film containing a thermoplastic resin. The positive electrode resin layer may have a single-layer structure or a multi-layer laminated structure.

[0262] Positive conductive layer

[0263] As the material of the positive electrode conductive layer of the positive electrode composite film, aluminum, titanium, chromium, stainless steel or nickel, or an alloy containing one or more of them can be used. The positive electrode conductive layer is, for example, a conductive film containing aluminum, such as an aluminum film, an aluminum alloy film, etc. As the positive electrode conductive layer, a conductive film with aluminum as the main component can also be used. "As the main component" includes substances in which the aluminum content in the conductive film is, for example, 80% by weight or more. Therefore, it is easy to plastically deform the positive electrode conductive layer into a prescribed shape by the method described later, so it is advantageous. The material of the first conductive layer arranged on the first surface of the positive electrode resin layer and the material of the second conductive layer arranged on the second surface of the positive electrode resin layer are typically the same, but they may also be different from each other.

[0264] The positive electrode conductive layer can be formed by a known semiconductor process. For example, vapor deposition, sputtering, electrolytic plating, electroless plating, etc. may also be used. The thickness of each positive electrode conductive layer can be, for example, 50 nm or more and 5 μm or less, preferably 100 nm or more and 2 μm or less. More preferably, it is 0.5 μm or more and 1 μm or less. The positive electrode conductive layer is not limited to a single layer. One or both of the positive electrode conductive layers may include multiple layers. A protective layer for inhibiting oxidation may also be further formed on the surface of the positive electrode conductive layer.

[0265] Among them, such as Figure 9 As shown in the example, another solid layer ( Figure 8 The solid layer 70 is shown as an example. The solid layer may be, for example, a primer layer or anchor coating layer for strengthening the bond between the conductive material and the resin layer. The primer layer or anchor coating layer may be an organic layer such as an acrylic resin or a polyolefin resin, or a metal layer formed by sputtering or the like. Providing the primer layer can further strengthen the bond between the positive electrode conductive layer and the positive electrode resin layer and / or suppress the formation of pinholes in the positive electrode conductive layer.

[0266] (Positive electrode material layer)

[0267] The positive electrode material layer contains, for example, a material capable of absorbing and releasing lithium ions as a positive electrode active material. The content of the positive electrode active material in the positive electrode material layer is, for example, 80 to 97% by mass. The positive electrode material layer may also contain a binder, a conductive additive, etc. A carbon-containing undercoat layer may be interposed between the positive electrode composite film and the positive electrode material layer.

[0268] In the case where the positive electrode material layer is a particle layer, the particles p1 ( Figure 5 ) may be positive electrode active material particles, or conductive particles used as a conductive auxiliary agent, etc. Particles p1 are preferably positive electrode active material particles.

[0269] The average particle size of the positive electrode active material used in the formation of the positive electrode material layer is, for example, 1 to 10 μm, and the aspect ratio of the particles is, for example, 1 to 5. Alternatively, the positive electrode material layer can be formed using secondary particles (for example, secondary particle size: 10 to 30 μm) obtained by granulating such particles. The particles of the positive electrode active material can be deformed by a rolling process, etc., when forming the positive electrode material layer. Sometimes cracks or cracks are generated on some particles. Therefore, although it also depends on the formation conditions of the active material layer, the size of the positive electrode active material particles contained in the formed positive electrode material layer is sometimes different from the size of the above-mentioned particles. The particle size, shape, etc. of the positive electrode active material particles in the positive electrode material layer can be obtained by particle analysis using the above-mentioned "AZOKUN".

[0270] Examples of materials capable of absorbing and releasing lithium ions are composite metal oxides containing lithium. Examples of such composite metal oxides include lithium cobaltate (LiCoO2), lithium nickelate (LiNiO2), lithium manganese oxide (LiMnO2), lithium manganese spinel (LiMn2O4), lithium vanadium compounds (LiV2O5), olivine-type LiMPO4 (wherein M is one or more elements selected from Co, Ni, Mn, Fe, Mg, Nb, Ti, Al, and Zr, or vanadium oxide), lithium titanate (Li4Ti5O 12 ), general formula: LiNi x Co y Mn z A composite metal oxide represented by MaO2 (x+y+z+a=1, 0≤x<1, 0≤y<1, 0≤z<1, 0≤a<1, M in the above general formula is one or more elements selected from Al, Mg, Nb, Ti, Cu, Zn, Cr), and the general formula: LiNi x Co y Al z A composite metal oxide represented by O2 (0.9<x+y+z<1.1), etc. The positive electrode material layer may contain polyacetylene, polyaniline, polypyrrole, polythiophene, polyacene, etc. as a material capable of absorbing and releasing lithium ions.

[0271] Adhesive can use known various materials. As the adhesive in the positive electrode material layer, fluororesins such as polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), ethylene-tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE) and polyvinyl fluoride (PVF) can be used.

[0272] As a binder, vinylidene fluoride fluororubber can also be used. For example, vinylidene fluoride-hexafluoropropylene fluororubber (VDF-HFP fluororubber), vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene fluororubber (VDF-HFP-TFE fluororubber), vinylidene fluoride-pentafluoropropylene fluororubber (VDF-PFP fluororubber), vinylidene fluoride-pentafluoropropylene-tetrafluoroethylene fluororubber (VDF-PFP-TFE fluororubber), vinylidene fluoride-perfluoromethyl vinyl ether-tetrafluoroethylene fluororubber (VDF-PFMVE-TFE fluororubber), vinylidene fluoride-chlorotrifluoroethylene fluororubber (VDF-CTFE fluororubber) etc. can also be applied to the binder of the positive electrode material layer.

[0273] Examples of conductive additives include carbon materials such as carbon powder and carbon nanotubes. Carbon black, etc., can be used as the carbon powder. Other examples of conductive additives for the positive electrode material layer include metal powders such as nickel, stainless steel, and iron, and powders of conductive oxides such as ITO. A mixture of two or more of the above materials may also be included in the positive electrode material layer.

[0274] (Negative electrode composite membrane)

[0275] Negative electrode resin layer

[0276] The materials listed as examples for the positive electrode resin layer can be used as the material for the negative electrode resin layer of the negative electrode composite film. The material for the negative electrode resin layer may be the same as or different from that for the positive electrode resin layer. The preferred thickness range for the negative electrode resin layer can be the same as that listed for the positive electrode resin layer.

[0277] Negative conductive layer

[0278] As the material for the negative electrode conductive layer of the negative electrode composite film, for example, a conductive film containing copper, such as a copper film or a copper alloy film, can be used. The material of the first conductive layer disposed on the first surface of the negative electrode resin layer and the material of the second conductive layer disposed on the second surface of the negative electrode resin layer are typically the same, but may be different.

[0279] The negative electrode conductive layer can be formed by a well-known semiconductor process. For example, evaporation, sputtering, electrolytic plating, electroless plating, etc. can also be used. For example, after forming a nickel chromium (NiCr) seed layer on the surface of the negative electrode resin layer by sputtering, a copper film is formed on the seed layer by electrolytic plating, thereby obtaining a negative electrode conductive layer. The negative electrode conductive layer is not limited to a single-layer film. The thickness of the negative electrode conductive layer can be, for example, 50 nm or more and 5 μm or less, preferably 100 nm or more and 2 μm or less. More preferably, it is 0.5 μm or more and 1 μm or less. A primer layer or the like can also be interposed between the negative electrode conductive layer and the negative electrode resin layer. In addition, a protective layer or the like can also be provided on the surface of the negative electrode conductive layer.

[0280] (Negative electrode material layer)

[0281] The negative electrode material layer contains, for example, a material capable of absorbing and releasing lithium ions as a negative electrode active material. Similar to the positive electrode material layer, the negative electrode material layer may further contain a binder, a conductive additive, and the like. A carbon-containing undercoat layer may also be interposed between the composite film and the negative electrode material layer.

[0282] Examples of materials that can adsorb and release lithium ions are carbon materials such as natural or artificial graphite, carbon nanotubes, difficult-to-graphitize carbon, easily-graphitized carbon (soft carbon), and low-temperature-sintered carbon. Other examples of materials that can be applied to the negative electrode material layer are alkali metals and alkaline earth metals such as metallic lithium, and metals such as tin or silicon that can form compounds with metals such as lithium. Silicon-carbon composite materials can also be applied to the negative electrode material layer. The negative electrode material layer can contain an amorphous compound (SiO x (0<x<2), tin dioxide, etc.), lithium titanate (Li4Ti5O 12 ) as a material capable of absorbing and releasing lithium ions.

[0283] As the binder and conductive additive of the negative electrode material layer, the materials exemplified as the binder and conductive additive applicable to the positive electrode material layer can be applied. As the binder of the negative electrode material layer, in addition to the materials mentioned above, cellulose, styrene-butadiene rubber, ethylene-propylene rubber, polyimide resin, polyamide-imide resin, acrylic resin, etc. can be used.

[0284] (Leads 250, 260)

[0285] Leads 250 and 260 are plate-shaped members formed of a conductive material. The positive electrode lead 250 and the negative electrode lead 260 are made of, for example, aluminum or an aluminum alloy, and the negative electrode lead 250 and 260 are made of, for example, nickel or a nickel alloy.

[0286] Each of the leads 250 and 260 is, for example, a rectangular conductive plate. The shapes of the leads 250 and 260 are not limited to rectangular plates. They can adopt various shapes, such as a shape bent into an L shape when viewed perpendicular to the XY plane, a shape having a through hole, or a shape bent in the Z direction.

[0287] (1st floor 170A)

[0288] The first layer 170A is an insulating member that prevents electrical short circuits between the first electrode 110A and the second electrode 120A while allowing lithium ions to pass through. The first layer 170A may also have a ceramic coating on its surface. The thickness of the ceramic coating is, for example, in the range of 2 μm to 5 μm. The first layer 170A has a thickness in the range of 5 μm to 30 μm, for example. The thickness of the first layer 170A is more preferably in the range of 8 μm to 20 μm.

[0289] When an electrolyte solution is used for electrolyte 290, an insulating porous material is used for first layer 170A. Typical examples of such porous materials include single-layer films or laminated films of polyolefins such as polyethylene and polypropylene, or non-woven fabrics made of at least one fiber selected from cellulose, polyester, polyacrylonitrile, polyimide, polyamide (e.g., aromatic polyamide), polyethylene, and polypropylene. Alternatively, first layer 170A may be a porous film. The electrolyte solution is not only disposed between the material layer on the first electrode 110A side and first layer 170A, and between the material layer on the second electrode 120A side and first layer 170A, but also within the voids within first layer 170A.

[0290] (Electrolyte 290)

[0291] As electrolyte 290, for example, a non-aqueous electrolyte containing a metal salt such as a lithium salt and an organic solvent can be used. Examples of lithium salts include LiPF6, LiClO4, LiBF4, LiCF3SO3, LiCF3CF2SO3, LiC(CF3SO2)3, LiN(CF3SO2)2, LiN(CF3CF2SO2)2, LiN(CF3SO2)(C4F9SO2), LiN(CF3CF2CO)2, and LiBOB. One of these lithium salts may be used alone, or two or more may be mixed. From the perspective of ionization, electrolyte 290 preferably contains LiPF6.

[0292] The solvent of the electrolyte 290 can be, for example, an organic solvent containing a cyclic carbonate and a chain carbonate. Examples of cyclic carbonates that can be used for the electrolyte 290 are ethylene carbonate, propylene carbonate, butylene carbonate, and the like. It is beneficial for the organic solvent to contain at least propylene carbonate as the cyclic carbonate. The addition of the chain carbonate reduces the kinematic viscosity of the organic solvent. As the chain carbonate, diethyl carbonate, dimethyl carbonate, or ethyl methyl carbonate can be used. The volume ratio between the cyclic carbonate and the chain carbonate in the non-aqueous solvent is preferably in the range of 1:9 to 1:1. The organic solvent may further contain methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ-butyrolactone, 1,2-dimethoxyethane, 1,2-diethoxyethane, and the like.

[0293] The concentration of the electrolyte in the non-aqueous electrolyte is beneficially within a range of 0.5 mol / L or more and 2.0 mol / L or less. When the electrolyte concentration is 0.5 mol / L or more, the lithium ion concentration in the non-aqueous electrolyte becomes necessary and sufficient, and the ion conduction of the lithium ions in the non-aqueous electrolyte is suitable, so it is easy to obtain sufficient capacity during charge and discharge. When the electrolyte concentration is 2.0 mol / L or less, the lithium ions in the electrolyte can be fully coordinated by the solvent, so the reduction in the ion conduction of the lithium ions in the non-aqueous electrolyte is suppressed, and it is easy to obtain sufficient capacity during charge and discharge.

[0294] A solid electrolyte layer may also be used as the electrolyte 290. As the material of the solid electrolyte layer, a material selected from La 0.5 Li 0.5 TiO3 and other perovskite compounds, Li 14 Zn(GeO4)4 and other LISICON type (lithium superion conductor type) compounds, Li7La3Zr2O 12 Garnet compounds, LiZr2(PO4)3, Li 1.3 Al 0.3 Ti 1.7 (PO4)3、Li 1.5 Al 0.5 Ge 1.5 (PO4)3 and other NASICON (sodium superion conductor) type compounds, Li 3.25 Ge 0.25 P 0.75 S4, Li3PS4 and other sulfide crystal lithium superion conductor (thio-LISICON) type compounds, Li2S-P2S5, Li2O-V2O5-SiO2 and other glass compounds, and Li3PO4, Li 3.5 Si 0.5 P 0.5 O4、Li 2.9 PO 3.3 N 0.46 At least one of the phosphate compounds.

[0295] (Exterior body 300)

[0296] The outer casing 300 is a covering member that holds the cell 2002 and the electrolyte 290 therein. The outer casing 300 protects the cell 2002 and the electrolyte 290 from external influences such as moisture. In a configuration where an electrolyte solution is used as the electrolyte 290, the outer casing 300 also prevents the electrolyte solution from leaking to the outside.

[0297] The outer casing 300 is, for example, a laminated film having resin films formed on both sides of a metal foil. A representative example of the metal foil used in the laminated film of the outer casing 300 is aluminum foil. The resin coating the metal foil can be a polymer such as polypropylene. The material of the resin film covering the surface of the metal foil on the side of the single cell 2002 (the inner surface of the outer casing 300) and the material of the resin film covering the surface on the opposite side of the single cell 2002 may be the same as or different from the material of the resin film covering the surface on the opposite side of the single cell 2002. For example, the surface of the metal foil on the side of the single cell 2002 may be covered with polyethylene, polypropylene, etc., and the surface on the opposite side may be covered with a resin material having a higher melting point, such as polyethylene terephthalate, polyamide (PA), etc.

[0298] As the outer body 300, in addition to the laminated film, a metal can or the like can also be applied. When a metal can is applied to the outer body 300, a valve for discharging the gas generated inside is sometimes provided in the can. In addition, sometimes both the positive and negative electrodes are provided with active material layers on both sides of the composite film serving as the current collector. In such a structure, the active material layer is located at the outermost side of the single cell 2002, and sometimes a protective member or the like for ensuring electrical insulation is provided between the can serving as the outer body 300 and the single cell 2002. As the material of such a protective member, the same material as the diaphragm 270 can be applied.

[0299] The exterior body 300 may be a covering member made of a resin formed by curing epoxy resin or the like. In other words, the exterior body 300 may be a resin itself formed by potting.

[0300] (Example)

[0301] [Relationship between the shape of the conductive layer of the electrode and battery characteristics 1]

[0302] The relationship between the shape of the electrode's conductive layer and battery performance was investigated. Batteries 1 to 4 were prepared, each using a composite film containing conductive layers on both sides of a resin layer as the positive electrode. Metal foil was used as the current collector in the negative electrode of each battery. Next, charge and discharge tests were conducted on each battery to evaluate rate characteristics. The positive electrode was then removed from each battery and its cross-section observed.

[0303] <Electrode 1>

[0304] (Battery Production)

[0305] The electrode 1 uses a composite film as a current collector of the positive electrode and a copper foil as a current collector of the negative electrode.

[0306] First, a composite film was prepared in which aluminum films were formed as conductive layers on both sides of a resin layer. A 6-μm-thick polyethylene terephthalate sheet was used as the resin layer. Next, aluminum films were formed on both sides of the polyethylene terephthalate sheet by vapor deposition to a thickness of 0.8 to 0.9 μm, resulting in a composite film with a thickness of approximately 8 μm.

[0307] Next, a positive electrode active material particle layer is formed on both sides of the composite film as a particle layer. In this embodiment, LiCoO2 (LCO) is used as the positive electrode active material. Relative to 100 parts by mass of the positive electrode active material, acetylene black as a conductive aid and polyvinylidene fluoride (PVDF) as a binder are weighed in a ratio of 1 to 3 parts by mass, and they are mixed to obtain a positive electrode mixture. Next, the positive electrode mixture is dispersed in N-methyl-2-pyrrolidone to obtain a paste-like positive electrode mixture coating. The coating is applied in an amount of 10 to 20 mg / cm2 of the positive electrode active material.2 The positive electrode active material particle layer is formed by coating both surfaces of the composite film with a coating method and drying at 60-100°C. The positive electrode active material particle layer is not formed on the portion of the composite film that will become the tab area. The film is then pressurized using a roll press.

[0308] As described above, the conditions for rolling (temperature, linear pressure, conveying speed, etc.) are appropriately set according to the material and thickness of the conductive layer, the thickness and flexibility of the resin layer, etc., to obtain the desired first shape. The linear pressure of rolling can be set to 10,000 to 30,000 N / cm, for example. In addition, the temperature of the roller during rolling (hereinafter referred to as "the temperature during rolling") can be set to 25 to 80°C, for example. In battery 1, the linear pressure of rolling is set to 25,000 N / cm, and the temperature during rolling is set to room temperature (for example, 25°C). The conveying speed is 10 to 20 m / min. In this way, a positive electrode is produced.

[0309] Next, a negative electrode is prepared. In this embodiment, graphite is used as the negative electrode active material. Relative to 100 parts by mass of the negative electrode active material, 0 to 3 parts by mass of acetylene black as a conductive aid and 1 to 3 parts by mass of styrene-butadiene rubber (SBR) as a binder are weighed and mixed to obtain a negative electrode mixture. Next, the negative electrode mixture is dispersed in a carboxymethyl cellulose aqueous solution (CMC) to prepare a paste-like negative electrode mixture coating. The coating is applied in an amount of 7 to 12 mg / cm2 of the negative electrode active material. 2 The negative electrode active material layer is formed by coating each surface of an 8μm thick electrolytic copper foil and drying at 80-110°C. No negative electrode active material layer is formed on the portion of the copper foil that will become the tab area. Next, the negative electrode active material layer is pressed using a roller press. The roller pressing conditions are as follows: a linear pressure of 10,000-30,000 N / cm and a conveying speed of 10-20 m / min. In this way, a negative electrode is produced.

[0310] Next, the prepared negative and positive electrodes were alternately stacked with 12 μm-thick polyethylene separators interposed therebetween to create a stack consisting of six negative electrodes and five positive electrodes. A nickel negative electrode lead was then attached to the tab area of ​​the negative electrode of the stack, while an aluminum positive electrode lead was attached to the tab area of ​​the positive electrode of the stack using an ultrasonic welder.

[0311] Then, the stack is inserted into the outer body of the aluminum laminate film and heat-sealed except for one part of the outer body to form an opening. A non-aqueous electrolyte is injected into the outer body. Here, a non-aqueous electrolyte with 1M (mol / L) of LiPF6 as a lithium salt added to a solvent containing EC (ethylene carbonate) / DEC (diethyl carbonate) in a volume ratio of 3:7 is used. Then, the remaining part is sealed by heat sealing while being decompressed using a vacuum sealing machine. In this way, a lithium ion secondary battery is produced as battery 1.

[0312] (Measurement of rate characteristics)

[0313] Next, the fabricated batteries were subjected to a charge-discharge cycle test to measure rate characteristics.

[0314] The battery 1 produced above was first charged at a constant current rate of 0.2C (the current value at which charging is completed within 5 hours at 25°C) using a secondary battery charge and discharge tester (manufactured by Hokuto Denko Co., Ltd.) until the battery voltage reached 4.2V. Then, the battery was discharged at a constant current rate of 0.2C until the battery voltage reached 2.8V, and the initial discharge capacity C1 was determined.

[0315] Next, constant current charging was performed at a charge rate of 0.2C (the current value at which charging is completed within 5 hours at 25°C) until the battery voltage reached 4.2 V. Then, constant current discharge was performed at a discharge rate of 2C (the current value at which charging is completed within 0.5 hours at 25°C) until the battery voltage reached 2.8 V. The 2C discharge capacity C2 was calculated.

[0316] Next, the 2C rate characteristic was determined from the initial discharge capacity C1 and the 2C discharge capacity C2 according to the following formula.

[0317] 2C rate characteristics [%] = C2 / C1×100

[0318] (Observation of the positive electrode cross section)

[0319] After the characteristic evaluation, the battery was disassembled, the positive electrode removed, cleaned with dimethyl carbonate (DMC), and dried. A cross-section of the positive electrode was then polished using a polishing machine, and the resulting observation sample was observed using a SEM at a magnification of 5000x.

[0320] Here, for the positive electrode of each battery, 5 observation samples with different cross-sectional directions are made, and 5 unit cross sections are observed. The width (length) L of each unit cross section is set to 25μm. First, the Z direction of each unit cross section and the vertex of the convex portion are determined by the above method. Next, the image of each unit cross section is analyzed, and the distance H, the number of convex portions Na, and the depth d2 of the concave portion are measured for the first conductive layer and the second conductive layer respectively. Then, the distance H, the number of convex portions Na, and the distance dm2 (the average of the depth d2 of the concave portion) of the 5 unit cross sections are calculated. Furthermore, based on these unit cross sections, the presence or absence of a gap g between each conductive layer and the resin layer is investigated.

[0321] <Batteries 2-4>

[0322] Batteries 2, 3, and 4 were fabricated using the same method as Battery 1, except for the temperature during roll pressing when forming the positive electrode active material particle layer. The roll pressing temperature was set at 50°C for Battery 2, 60°C for Battery 3, and 80°C for Battery 4. The pressing conditions for Batteries 1 to 4 are shown in Table 1. Rate characteristics of Batteries 2, 3, and 4 were measured using the same method as for Battery 1, and cross-sections of the positive electrodes were then observed.

[0323] [Table 1]

[0324]

[0325] (result)

[0326] Relationship between rate characteristics and the shape of the conductive layer of the positive electrode (deepness d2)

[0327] Observation of the cross sections of the positive electrodes of Batteries 1 to 4 revealed that no gap g was formed between the conductive layer and the resin layer in any of the batteries. Furthermore, for each battery, the average value of the distance H of the five unit cross sections was confirmed to be sufficiently smaller than the thickness T of the resin layer.

[0328] Table 2 shows the measurement results of rate characteristics and positive electrode distance dm2 for batteries 1 to 4. Distance dm2 shown in Table 2 is the average value of the recess depth d2 in the first and second conductive layers of the positive electrodes of the batteries.

[0329] [Table 2]

[0330] Distance dm2 (μm) Rate characteristics (%) Battery 1 0.18 73 Battery 2 0.25 81 Battery 3 0.46 82 Battery 4 0.71 75

[0331] Table 2 shows that all of Batteries 1 to 4 have high rate characteristics. In addition, it is found that the distance dm2 of the positive electrodes of Batteries 1 to 4 increases as the temperature during roller pressing increases.

[0332] As shown in Table 2, as the distance dm2 of the positive electrode increases, the rate characteristics improve. It is believed that this is because the greater the distance dm2 (i.e., the depth of the recessed portion of the conductive layer), the more effectively the stress applied to the conductive layer can be reduced, and the more the conductivity of the positive electrode can be suppressed. On the other hand, it is known that if the distance dm2 exceeds a certain value, there is a tendency for the rate characteristics to decrease. It is believed that this is because the depth of the recessed portion of the conductive layer becomes too large relative to the size of the particles, so the effect of reducing stress as described above becomes smaller.

[0333] Observation results of the positive electrode

[0334] Taking the positive electrode of battery 2 as an example, the values ​​of various parameters obtained by cross-sectional observation of the positive electrode are shown in Tables 3 and 4. Here, for one sheet of positive electrode used in battery 2, images of five unit cross-sections U2-1 to U2-5 were analyzed. Figure 15 This is a diagram showing a SEM image of a unit cross section U2 - 1 of the battery 2 as a line graph.

[0335] [Table 3]

[0336]

[0337] [Table 4]

[0338]

[0339] [Relationship between the shape of the conductive layer of the electrode and battery characteristics 2]

[0340] The relationship between the shape of the electrode's conductive layer and the shape of the gap g within the electrode and battery characteristics was investigated. Batteries 5 to 8 were produced, each using a composite film containing conductive layers on both sides of a resin layer as a positive electrode. These differ from Batteries 1 to 4 in that the positive electrode had a gap g between the conductive layer and the resin layer.

[0341] <Batteries 5-8>

[0342] Batteries 5 to 8 were produced using the same method as Battery 1, except for the pressing conditions during the formation of the positive electrode active material particle layer (roll pressing temperature and linear pressure). In Battery 5, the roll pressing temperature was set to 50°C and the linear pressure was set to 25,000 N / cm. In Battery 6, the roll pressing temperature was set to 50°C and the linear pressure was set to 30,000 N / cm. In Battery 7, the roll pressing temperature was set to 40°C and the linear pressure was set to 30,000 N / cm. In Battery 8, the roll pressing temperature was set to 25°C and the linear pressure was set to 30,000 N / cm. The pressing conditions for Batteries 5 to 8 are also shown in Table 1.

[0343] Next, the rate characteristics of fabricated Batteries 5 to 8 were measured using the same measurement method as for Battery 1. After the characteristic evaluation, the batteries were disassembled to remove the positive electrodes. Positive electrode observation samples were prepared using the same method as for Battery 1, and the cross-sections of the positive electrodes were observed using a SEM.

[0344] Here, three observation samples having different cross-sectional directions were prepared, and three unit cross sections were observed. The width (length) L of each unit cross section was set to 25 μm.

[0345] First, using the same method as for battery 1, the average values ​​of the distance H, the number of protrusions Na, and the depth d2 of the recesses in five unit cross-sections of the positive electrode of each battery were calculated. Furthermore, since the positive electrodes of batteries 5 to 8 have gaps g inside, the gaps g were also analyzed. Specifically, for each unit cross-section, the ratio Tw / L of the total width Tw of the gaps g (i.e., the ratio LX / L of the total length LX of the first portion in contact with the gaps g) and the number Ng of recesses in contact with the gaps g were measured for each of the first and second conductive layers, and the average values ​​for the three unit cross-sections were calculated. Furthermore, for each unit cross-section, the height hg and width wg of each gap g located between the first and second conductive layers and the resin layer were measured, and the average values ​​of the height hg, width wg, and hg / wg of the gaps g contained in the three unit cross-sections were calculated.

[0346] (result)

[0347] Relationship between rate characteristics and the shape of the positive electrode (distance dm2) and the shape of the gap g

[0348] Observation of the cross-sections of the positive electrodes of batteries 5 to 8 confirmed that a gap g was formed between the conductive layer and the resin layer in all batteries. Furthermore, for each battery, the average value of the distance H across the three unit cross-sections was sufficiently smaller than the thickness T of the resin layer. Furthermore, it was found that the average value of the hg / wg ratio of the gap g could vary depending on the pressing conditions (here, the temperature and linear pressure during roll pressing). Therefore, it was confirmed that the hg / wg ratio of the gap g could be controlled by adjusting the pressing conditions, for example.

[0349] Table 5 shows the measurement results of the rate characteristics of Batteries 5 to 8, along with the measurement results of the distance dm2 and hg / wg. The distance dm2 shown in Table 5 is the average value of the distance d2 between the first and second conductive layers of the positive electrode of each battery. The hg / wg shown in Table 5 is the average value of the hg / wg of the gap between the first and second conductive layers and the resin layer of the positive electrode of each battery.

[0350] [Table 5]

[0351] Distance dm2 (μm) hg / wg of gap g Rate characteristics (%) Battery 5 0.27 9.8 81 Battery 6 0.25 16.7 85 Battery 7 0.22 16.2 87 Battery 8 0.29 28.1 82

[0352] Table 5 shows that the distance dm2 of batteries 5 to 8 is approximately the same as the distance dm2 of electrode 2 (0.25), yet the rate characteristics of batteries 5 to 8 are at least as good as the rate characteristics of battery 2 (81%). This confirms that providing a gap g between the conductive layer and the resin layer further improves rate characteristics. This is believed to be because the internal stress of the conductive layer is alleviated by the gap g, suppressing the increase in resistance or degradation of the electrode caused by internal stress.

[0353] In addition, among batteries 5 to 8, the rate characteristics of batteries 6 and 7 are higher than those of the other batteries. Based on this result, it can be seen that although the rate characteristics improve as the hg / wg of the gap g increases, if hg / wg exceeds a certain value, there is a tendency for the rate characteristics to decrease. This is believed to be because the larger the hg / wg (i.e., the ratio of the height to the width of the gap), the greater the effect of relieving the internal stress of the conductive layer. On the other hand, if hg / wg becomes too large, it is difficult for the resin layer to absorb the stress applied to the conductive layer from the particle layer due to the presence of the gap, so it is believed that the conductivity of the conductive layer decreases.

[0354] Observation results of the positive electrode

[0355] Taking the positive electrodes of Battery 6 and Battery 7 as examples, the values ​​of various parameters obtained by cross-sectional observation of the positive electrodes are shown in Tables 6 and 7. Here, for one positive electrode used in Battery 6, images of three unit cross sections U6-1 to U6-3 were analyzed. Figure 23 This is a schematic diagram showing a SEM image of a unit cross section U6-1 of the battery 6 of the embodiment using a line graph. Figure 23 In FIG. 1 , the recessed portions in contact with the gap are denoted by reference numerals g1 to g8 .

[0356] As shown in Tables 6 and 7, the ratio XL / L, corresponding to the ratio of gap g, was 0.28 or greater in both Battery 6 and Battery 7, and the number of recesses contacting the gaps was 0.8 or greater relative to the total number of recesses in the conductive layer of each battery. Therefore, it is believed that the inclusion of gaps with appropriately controlled cross-sectional shapes at a high ratio (e.g., XL / L of 0.28 or greater) enables particularly excellent rate characteristics to be achieved.

[0357] [Table 6]

[0358]

[0359] [Table 7]

[0360]

[0361] Industrial applicability

[0362] The electrodes for energy storage devices according to the embodiments of the present disclosure are useful as power sources for various electronic devices, electric motors, etc. For example, the energy storage devices according to the embodiments of the present disclosure can be applied as power sources for vehicles such as bicycles and passenger cars, power sources for communication devices such as smartphones, power sources for various sensors, and power sources for unmanned eXtended Vehicles (UxVs).

Claims

1. An electrode for an electricity storage device, characterized in that: include: a resin layer having a first surface and a second surface located on the opposite side of the first surface; a first conductive layer located on the first surface side of the resin layer; and a first particle layer located on the side of the first conductive layer opposite to the resin layer; In a cross section parallel to the thickness direction of the resin layer, The first conductive layer has a first shape including a plurality of convex portions curved convexly toward the resin layer and a concave portion disposed between two adjacent convex portions among the plurality of convex portions. The distance H in the thickness direction from one of the vertices of the two adjacent convex portions to the bottom point of the concave portion is smaller than the thickness of the resin layer. In a cross section parallel to the thickness direction, There is one or more gaps between the first conductive layer and the first surface of the resin layer, Each gap is located between two adjacent convex portions among the plurality of convex portions.

2. An electrode for an electricity storage device, characterized in that: include: a resin layer having a first surface and a second surface located opposite to the first surface; a first conductive layer located on the first surface side of the resin layer; and a first particle layer located on the side of the first conductive layer opposite to the resin layer; In a cross section parallel to the thickness direction of the resin layer, the first conductive layer has a first shape, the first shape being a first wavy shape including a plurality of convex portions that are convexly bent toward the resin layer, the amplitude of the first wavy shape in the thickness direction being smaller than the thickness of the resin layer. In a cross section parallel to the thickness direction, There is one or more gaps between the first conductive layer and the first surface of the resin layer, Each gap is located between two adjacent convex portions among the plurality of convex portions.

3. The electrode for a power storage device according to claim 1 or 2, wherein: In a cross section parallel to the thickness direction, the first shape of the first conductive layer has two recessed portions located on both sides of one of the plurality of projections. At least a portion of the particles contained in the first particle layer is located between the two recessed portions.

4. The electrode for an electricity storage device according to claim 1 or 2, wherein: In a cross section parallel to the thickness direction, the first surface of the resin layer includes a plurality of first concave regions. At least a portion of one of the plurality of convex portions is located inside each of the plurality of first concave regions.

5. The electrode for an electricity storage device according to claim 1 or 2, wherein: The first particle layer includes a plurality of active material particles.

6. The electrode for a power storage device according to claim 1 or 2, wherein: In a unit cross section having a length L of 25 μm in a cross section parallel to the thickness direction and perpendicular to the thickness direction of the resin layer, The first shape of the first conductive layer has a plurality of recesses, each of which is located between two adjacent convex portions among the plurality of convex portions, and the number of recesses in contact with the one or more gaps is greater than or equal to 1 and less than or equal to 10.

7. The electrode for an electricity storage device according to claim 1 or 2, wherein: In a unit cross-section parallel to the thickness direction and having a length L of 25 μm in the width direction perpendicular to the thickness direction of the resin layer, the total width wg of the one or more gaps perpendicular to the thickness direction is Tw, and the ratio Tw to the length L is Tw / L greater than 0.02 and less than 0.

5.

8. The electrode for an electricity storage device according to claim 1 or 2, wherein: In a cross section parallel to the thickness direction, The plurality of protrusions of the first conductive layer include two protrusions in contact with the first surface of the resin layer. The first conductive layer has a first portion spaced apart from the first surface between two protrusions in contact with the first surface.

9. The electrode for an electricity storage device according to claim 8, wherein: In a unit cross section parallel to the thickness direction and having a width direction length L perpendicular to the thickness direction of the resin layer of 25 μm, a ratio LX / L of the total length LX of the first portion in the width direction to the length L is greater than or equal to 0.02 and less than or equal to 0.

5.

10. The electrode for an electricity storage device according to claim 1 or 2, wherein: The number of the plurality of projections is 2 or more and 10 or less in a unit cross section having a length of 25 μm in a width direction perpendicular to the thickness direction of the resin layer and parallel to the thickness direction.

11. The electrode for an electricity storage device according to claim 4, wherein: The number of the plurality of first concave regions in a unit cross section having a length of 25 μm in a cross section parallel to the thickness direction and in a width direction perpendicular to the thickness direction of the resin layer is 1 or more and 10 or less.

12. The electrode for an electricity storage device according to claim 1 or 2, wherein: In a unit cross-section parallel to the thickness direction and having a length L of 25 μm in the width direction perpendicular to the thickness direction of the resin layer, a ratio Lm / L of the length Lm of the surface of the first conductive layer on the resin layer side to the length L is greater than 1.04 and less than 1.

20.

13. The electrode for a power storage device according to claim 1 or 2, wherein: In a unit cross-section parallel to the thickness direction and having a length L of 25 μm in the width direction perpendicular to the thickness direction of the resin layer, the maximum value of the distance d2 between a line segment connecting the vertices of two adjacent protrusions among the multiple protrusions and the point farthest from the line segment in the concave portion between them is greater than 0.2 μm and less than 3.0 μm.

14. The electrode for an electricity storage device according to claim 6, wherein: In the unit cross section, a height hg of each of the gaps perpendicular to the thickness direction is greater than 0 and is 3 μm or less.

15. The electrode for a power storage device according to claim 6, wherein: In the unit cross section, a ratio wg / hg of a height hg of each gap along the thickness direction to a width wg perpendicular to the thickness direction is greater than or equal to 1 and less than or equal to 20.

16. The electrode for a power storage device according to claim 1 or 2, wherein: In a unit cross section having a length of 25 μm in a cross section parallel to the thickness direction and in a width direction perpendicular to the thickness direction of the resin layer, the thinnest portion of the first conductive layer is located at any one of the plurality of projections.

17. The electrode for an electricity storage device according to claim 1, wherein: In a cross section parallel to the thickness direction, the distance H is less than ½ of the thickness of the resin layer.

18. The electrode for an electricity storage device according to claim 1 or 2, wherein: Also includes: a second conductive layer located on the second surface side of the resin layer; and a second particle layer located on the side of the second conductive layer opposite to the resin layer, In a cross section parallel to the thickness direction, the second conductive layer has a second shape including a plurality of second protrusions that are convexly curved toward the resin layer.

19. The electrode for a power storage device according to claim 18, wherein: In a cross section parallel to the thickness direction, The plurality of second protrusions include a protrusion that at least partially overlaps with one of the plurality of protrusions in the first shape in the thickness direction, and a protrusion that does not overlap with any of the plurality of protrusions.

20. The electrode for an electricity storage device according to claim 1 or 2, wherein: The first conductive layer is thinner than the resin layer. The thickness of the first conductive layer is greater than or equal to 0.3 μm and less than or equal to 1.5 μm. The thickness of the resin layer is greater than or equal to 3 μm and less than or equal to 10 μm.

21. The electrode for an electricity storage device according to claim 1 or 2, wherein: The first conductive layer contains aluminum as a main component, The resin layer includes at least one of polyethylene terephthalate, polypropylene, polyamide, polyimide, polyethylene, polystyrene, phenolic resin, and epoxy resin.

22. A lithium-ion secondary battery, characterized in that: include: positive electrode; negative electrode; a separator disposed between the negative electrode and the positive electrode; and a non-aqueous electrolyte containing lithium ions, The positive electrode is the electrode for an electricity storage device according to any one of claims 1 to 21.

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