WO2022208682A1 - 蓄電デバイス用電極およびリチウムイオン二次電池 - Google Patents

蓄電デバイス用電極およびリチウムイオン二次電池 Download PDF

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Publication number
WO2022208682A1
WO2022208682A1 PCT/JP2021/013638 JP2021013638W WO2022208682A1 WO 2022208682 A1 WO2022208682 A1 WO 2022208682A1 JP 2021013638 W JP2021013638 W JP 2021013638W WO 2022208682 A1 WO2022208682 A1 WO 2022208682A1
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WIPO (PCT)
Prior art keywords
conductive layer
layer
resin layer
thickness direction
cross
Prior art date
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Ceased
Application number
PCT/JP2021/013638
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English (en)
French (fr)
Japanese (ja)
Inventor
卓也 青木
修二 東
修司 塚本
圭祐 立嵜
浩介 田中
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TDK Corp
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TDK Corp
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Publication date
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Priority to PCT/JP2021/013638 priority Critical patent/WO2022208682A1/ja
Priority to CN202180004947.8A priority patent/CN115428196B/zh
Priority to US17/634,391 priority patent/US20230361313A1/en
Priority to JP2022508492A priority patent/JP7392828B2/ja
Publication of WO2022208682A1 publication Critical patent/WO2022208682A1/ja
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/70—Carriers or collectors characterised by shape or form
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/661—Metal or alloys, e.g. alloy coatings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present disclosure relates to electrodes for power storage devices and lithium ion secondary batteries.
  • Patent Documents 1 and 2 below disclose electrodes for secondary batteries in which such a composite material is applied to a current collector.
  • An embodiment of the present disclosure provides an electricity storage device electrode capable of improving the rate characteristics of the electricity storage device.
  • An electricity storage device electrode includes a resin layer having a first surface and a second surface located opposite to the first surface, and a first surface located on the first surface side of the resin layer.
  • the first conductive layer includes a conductive layer and a first particle layer located on the opposite side of the resin layer, and in a cross section parallel to the thickness direction of the resin layer, the first conductive layer is the resin layer.
  • the first shape includes a plurality of convex portions curved convexly toward the layer side, and a concave portion disposed between two adjacent convex portions among the plurality of convex portions, and the two adjacent convex portions have a first shape.
  • a distance H in the thickness direction from one of the peaks of the protrusions to the bottom of the recesses is smaller than the thickness of the resin layer.
  • a power storage device electrode includes a resin layer having a first surface and a second surface located opposite to the first surface; and a first particle layer located on the side opposite to the resin layer of the first conductive layer.
  • the first conductive layer 1 shape In a cross section parallel to the thickness direction of the resin layer, the first conductive layer 1 shape, the first shape is a first wavy shape including a plurality of convex portions curved convexly toward the resin layer side, and the amplitude of the first wavy shape in the thickness direction is , less than the thickness of the resin layer.
  • an electricity storage device electrode is provided that can improve the rate characteristics of the electricity storage device.
  • FIG. 12 is an exploded perspective view of a first electrode according to certain embodiments of the present disclosure
  • FIG. 2 is a schematic cross-sectional view showing a part of a cross section parallel to the XZ plane of the first electrode shown in FIG. 1; It is a typical sectional view showing a part of the 1st electrode for explaining the shape of the 1st conductive layer.
  • FIG. 2 is a schematic cross-sectional view showing a part of a cross section parallel to the YZ plane of the first electrode shown in FIG. 1; It is a figure which shows a part of cross section of a 1st electrode, and is a schematic diagram based on a cross-sectional SEM image.
  • FIG. 2 is a schematic cross-sectional view showing a part of a cross section parallel to the XZ plane of the first electrode shown in FIG. 1; It is a typical sectional view showing a part of the 1st electrode for explaining the shape of the 1st conductive layer.
  • FIG. 2 is a schematic
  • FIG. 4 is a schematic cross-sectional view showing a part of the first electrode for explaining the relationship between the particles of the particle layer and the first conductive layer;
  • FIG. 5 is a schematic cross-sectional view showing part of another example of the first electrode;
  • FIG. 5 is a schematic cross-sectional view showing part of another example of the first electrode;
  • FIG. 11 is a schematic cross-sectional view showing a part of still another example of the first electrode;
  • FIG. 11 is an exploded perspective view of a first electrode according to another embodiment of the present disclosure;
  • FIG. 2 is a schematic cross-sectional view showing part of the first electrode shown in FIG. 1; It is a schematic cross-sectional view showing a unit cross section of the first electrode for explaining a method of specifying the Z direction.
  • FIG. 5 is a schematic cross-sectional view showing part of another example of the first electrode
  • FIG. 5 is a schematic cross-sectional view showing part of another example of the first electrode
  • FIG. 11 is a schematic cross-section
  • FIG. 4 is a schematic cross-sectional view showing a part of a unit cross section of the first battery for explaining the distance H; It is a figure which shows a part of unit cross section of a 1st electrode, and is a schematic diagram based on a cross-sectional SEM image.
  • FIG. 4 is a schematic cross-sectional view showing a part of a unit cross section of the first electrode for explaining the height d1 of the protrusion and the depth d2 of the recess; 3 is a schematic diagram based on a cross-sectional SEM image showing a unit cross section U2-1 of battery 2 of Example 2.
  • FIG. 4 is a schematic cross-sectional view showing a part of a unit cross section of the first battery for explaining the distance H; It is a figure which shows a part of unit cross section of a 1st electrode, and is a schematic diagram based on a cross-sectional SEM image.
  • FIG. 4 is a schematic cross-sectional view showing a part of a unit
  • FIG. 4 is a schematic cross-sectional view showing a unit cross section of the first electrode for explaining parameters of the gap g; It is a figure which shows a part of cross section of the laminated film before forming a particle layer, and is a schematic diagram based on a cross-sectional SEM image.
  • 1 is a partial cutaway view showing an example of an electrical storage device;
  • FIG. FIG. 20 is an exploded perspective view showing a cell taken out from the electricity storage device shown in FIG. 19;
  • FIG. 4 is a partially cutaway view showing another example of an electricity storage device; 22 is an exploded perspective view showing cells and leads extracted from the electricity storage device shown in FIG. 21; FIG. FIG. 4 is a schematic diagram based on a cross-sectional SEM image showing a unit cross section U6-1 of Battery 6 of Example.
  • the term “cell” refers to a structure in which at least a pair of a positive electrode and a negative electrode are assembled together.
  • the term “battery” as used herein is used as an umbrella term for various forms such as battery modules, battery packs, etc., having one or more “cells” electrically connected to each other.
  • An embodiment of an electricity storage device electrode according to the present disclosure includes a resin layer having a first surface and a second surface, and a first conductive layer located on the first surface of the resin layer. and a first particle layer.
  • a "particle layer” is a layer containing a plurality of particles, and this layer may contain materials other than particles. The shape and size of the particles are not particularly limited as long as the first particle layer can adhere to the resin layer.
  • the first particle layer is located on the opposite side of the first conductive layer to the resin layer.
  • the first particle layer is, for example, an active material particle layer containing a plurality of active material particles.
  • the laminated film including the first conductive layer and the resin layer can function as a current collector.
  • laminated films are sometimes referred to as "composite films”.
  • the composite film may further 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 provided on both sides of a resin layer.
  • the conductive layer formed on the second surface of the resin layer is called "second conductive layer”.
  • the second conductive layer may also have a shape including a plurality of convex portions curved toward the resin layer in a cross section parallel to the thickness direction of the particle layer. Such a cross-sectional shape is called a "second shape”.
  • the first conductive layer and the second conductive layer may be collectively referred to as "conductive layer”.
  • the electrode of the present embodiment can be used as a positive electrode, a negative electrode, or both of an electric storage device such as a lithium ion secondary battery.
  • the electric storage device may have a single-layer cell consisting of a pair of positive and negative electrodes, or may have a laminated cell having a plurality of pairs of positive and negative electrodes.
  • one of the positive electrode and the negative electrode is sometimes called a "first electrode” and the other is called a "second electrode”.
  • the positive electrode and the negative electrode may be collectively referred to as "electrodes".
  • FIG. 1 and 2 are schematic diagrams showing an example of an electricity storage device electrode (hereinafter simply referred to as "electrode") of the present embodiment.
  • FIG. 1 is a schematic exploded view of an electrode.
  • FIG. 2 is a schematic cross-sectional view of the electrode shown in FIG. 1, and also shows an enlarged cross-sectional view of a region surrounded by a dotted line in the figure.
  • the electrodes used in a single-layer cell having only one pair of positive and negative electrodes are exemplified.
  • the drawings show arrows pointing in three mutually orthogonal directions, the X, Y and Z directions.
  • FIG. 2 shows a cross section parallel to the Z direction (a cross section perpendicular to the XY plane).
  • the first electrode 110 has a composite film 100 and a first material layer 111 supported by the composite film 100 .
  • Composite film 100 has an upper surface 100a and a lower surface 100b.
  • a first material layer 111 is disposed on the top surface 100 a of the composite film 100 .
  • the first material layer 111 is arranged only in a partial area of the composite film 100 .
  • the composite film 100 includes a region 110e overlapping the first material layer 111 when viewed in the Z direction, and a tab region 100t located outside the first material layer 111 (not overlapping the first material layer 111) when viewed in the Z direction. including.
  • the tab region 100t is used, for example, for connection with leads.
  • the composite film 100 has a resin layer 30 and the first conductive layer 10 supported by the resin layer 30.
  • the resin layer 30, the first conductive layer 10 and the first material layer 111 are laminated along the Z direction.
  • the Z direction is sometimes called "the thickness direction of the resin layer 30".
  • the resin layer 30 has a first surface 31 and a second surface 32 opposite to the first surface 31 .
  • the resin layer 30 has a thickness T.
  • the thickness T is, for example, the average distance in the Z direction between the first surface 31 and the second surface 32, as will be described later.
  • 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 of the resin layer 30 and an inner surface 10b located on the resin layer 30 side.
  • 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.
  • the "particle layer” may be a layer containing a plurality of particles, and may contain substances other than particles (eg, binder). Materials for the plurality of particles are not particularly limited.
  • the plurality of particles may include, for example, active material particles, conductive particles, or both.
  • the top 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 the second surface 32 of the resin layer 30, for example.
  • the composite film 100 may further have a second conductive layer located on the second surface 32 side of the resin layer 30 .
  • the lower surface 100b of the composite film 100 may be the outer surface of the second conductive layer.
  • terms including "upper” or “lower” such as “upper surface”, “lower surface”, “upper layer” and “lower layer” may be used. However, this is for the convenience of explaining the relative arrangement between the members, and is not intended to limit the attitude of the power storage device during use.
  • the "upper surface” refers to the surface located on the positive side in the Z direction of the drawing
  • the “lower surface” refers to the surface located on the negative side in the Z direction of the drawing.
  • the electrode structure in this embodiment will be described in further detail with reference to the enlarged view shown in FIG.
  • the shapes of the first conductive layer and the resin layer are mainly described using cross sections parallel to the Z direction.
  • "on a cross section parallel to the Z direction” may be simply described as “on a cross-sectional view”.
  • the first conductive layer 10 of the first electrode 110 includes a plurality of protrusions (sometimes referred to as "first protrusions") 11. It has a first shape.
  • the first shape may further include a recess 12 (sometimes referred to as a “first recess”) located between two adjacent protrusions 11 .
  • the first shape has multiple protrusions 11 and multiple recesses 12 .
  • Each convex portion 11 is a curved portion convexly curved toward the resin layer 30 in a cross-sectional view. That is, both surfaces (the outer surface 10a and the inner surface 10b) of the first conductive layer 10 are convexly curved toward the resin layer 30 at the convex portion 11 .
  • the "resin layer side” is the negative side (-Z side) in the Z direction.
  • the outer surface 10a and the inner surface 10b of the first conductive layer 10 are convexly curved in the same direction (toward the resin layer 30), but they do not have to be parallel to each other.
  • the convex portion 11 In a cross section parallel to the Z direction, the convex portion 11 as a whole only needs to be convexly curved toward the resin layer 30 side, and the upper surface and/or the lower surface of the convex portion 11 (in this example, the first conductive layer 10 portion of the outer surface 10a and the inner surface 10b of the ) may include steps, flat surfaces represented by straight lines, and the like.
  • a layer (or a surface) is "curved" in a cross-sectional view
  • the "curved shape" in a cross-sectional view may include not only a shape composed of one or more arcuate portions without corners, but also a shape composed of an arcuate portion and a straight portion.
  • arcuate means curved in a cross-sectional view, and is not limited to having an arched shape or drawing an arc.
  • Each convex portion 11 has a vertex 11a.
  • the inner surface 10b of the first conductive layer 10 is closest to the ⁇ Z side of the protrusion 11 (that is, the second surface 32 side of the resin layer 30). ).
  • the apex 11a is a minimum point on the surface of the convex portion 11 on the resin layer side. That is, each vertex 11a is a point corresponding to a minimum point when the shape of the inner surface 10b is regarded as a curved line in a cross-sectional view.
  • the convex portion 11 may have a substantially flat top surface at the top. If the top surface of the convex portion 11 is parallel to the XY plane, the vertex 11a may be an arbitrary point on the top surface.
  • Each concave portion 12 may 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 recess 12 may include a curved portion that is concavely curved with respect to the resin layer 30 or may include a flat portion that is not curved in a cross-sectional view. Alternatively, it may include a concave curved curve and a flat portion.
  • the "flat portion” includes, for example, a portion in which the outer surface 10a and the inner surface 10b of the first conductive layer 10 are shown as parallel straight lines in a cross-sectional view. In the cross section illustrated in FIG. 2 , each concave portion 12 is concavely curved with respect to the resin layer 30 .
  • the outer surface 10a and the inner surface 10b of the first conductive layer 10 are concavely curved with respect to the resin layer 30 at the recess 12 .
  • the outer surface 10a and the inner surface 10b of the first conductive layer 10 are curved in the same direction, but may not be parallel to each other.
  • Each recess 12 has a bottom point 12b.
  • the “bottom point of the recess” is, for example, the point located on the innermost surface 10b of the first conductive layer 10 on the +Z side of the recess 12 in a cross section parallel to the Z direction.
  • the bottom point 12b is the maximum point on the surface of the recess 12 on the resin layer side.
  • each bottom point 12b is a point corresponding to a maximum point when the shape of the inner surface 10b is regarded as a curve in a cross-sectional view.
  • the resin layer-side surface of each recess 12 may have a bottom surface parallel to the XY plane. The bottom point in this case may be any one point on the bottom surface.
  • FIG. 3 is a partially enlarged view for explaining the shape of the first conductive layer.
  • the curve representing the inner surface 10b of the first conductive layer 10 is located, for example, at the vertex (here, the minimum point) 11a1 of one convex portion 11 and the ⁇ X side of the convex portion 11.
  • An “inflection point” refers to a point at which a curve changes from downwardly convex to upwardly convex, or from downwardly convex to upwardly convex.
  • 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 boundary lines between the convex portion 11 and the concave portions 12 located on both sides thereof. good.
  • the width of the protrusion 11 in the X direction is, for example, the distance between the lines 15 and 16 .
  • the line indicating the inner surface 10b of the first conductive layer 10 includes a step or a straight portion, for example, by image analysis, an approximate curve indicating the inner surface 10b is obtained, An inflection point may be obtained from the curve.
  • the Z direction from one of the apexes 11a of two adjacent protrusions 11 of the first conductive layer 10 to the bottom point 12b of the recess 12 is smaller than the thickness T of the resin layer 30 .
  • the distance H between each of the plurality of protrusions 11 may be smaller than the thickness T. good.
  • the predetermined width may be, for example, a reference length L (for example, 25 ⁇ m), which will be described later.
  • the first shape of the first conductive layer 10 may be a wavy shape.
  • the “wavy shape” includes, for example, a “wavy” shape having a plurality of protrusions 11 and a plurality of recesses 12 repeatedly.
  • convex portions 11 curved convexly toward the resin layer 30 side and concave portions 12 including portions curved concavely toward the resin layer 30 side may be alternately arranged.
  • Waveforms include random variations in wave height, amplitude, or wavelength.
  • the first conductive layer 10 may have a wavy shape as a whole, and may include, for example, flat portions between convex portions.
  • the wavy shape of the first conductive layer 10 (sometimes referred to as “first wavy shape”) has an amplitude Am smaller than the thickness T of the resin layer 30 .
  • the amplitude Am may be obtained from the profile of the inner surface 10b of the first conductive layer 10 in a cross section parallel to the Z direction using image analysis software, for example. Observation, analysis, measurement, etc. of the amplitude may be performed in other ways. Observation can be performed by preparing an observation sample. For example, an observation sample is produced by embedding an electrode in a resin, exposing a cross section by polishing, and performing precision finishing of the cross section by ion milling.
  • the amplitude Am may be obtained by observing and analyzing the observation sample using, for example, a Keyence microscope or the like.
  • the point located on the most -Z side of the waveform shape and the point located on the most +Z side of the waveform shape A half of the distance in the Z direction may be obtained as the amplitude of the waveform shape.
  • the "first shape” and the “wavy shape” also include shapes that do not have regularity in the arrangement of the concave portions 12 and the convex portions 11.
  • the distance (corresponding to the wavelength of the waveform) in the X direction between the vertices 11a of two adjacent convex portions 11 may not be constant.
  • the arrangement pitch of the protrusions 11 may be random.
  • the arrangement pitch of the projections 11 is, for example, the distance between the vertexes 11a of the projections 11 in the X direction.
  • the sizes of the plurality of protrusions 11 and the sizes of the plurality of recesses 12 may not be uniform.
  • the arrangement pitch of the protrusions 11 in the first shape, the size of the protrusions 11 and the recesses 12, and the like can be obtained from a microscope image showing a cross section parallel to the Z direction, as described later.
  • the enlarged view shown in FIG. 2 shows a cross section (XZ cross section) of the first electrode 110 parallel to the X direction.
  • the first conductive layer 10 of the present embodiment has a first shape including a plurality of protrusions 11 even in a cross section parallel to another direction (eg, Y direction) intersecting the X direction among cross sections perpendicular to the XY plane. can have
  • FIG. 4 is a schematic diagram showing an enlarged part of the YZ cross section of the first electrode 110 shown in FIG.
  • the first conductive layer 10 also has a first shape including a plurality of protrusions 11 in a cross section parallel to the Y direction orthogonal to the X direction.
  • cross sections in directions other than the X direction and the Y direction are not illustrated, but the first conductive layer 10 may have the first shape also in cross sections in three or more different directions on the XY plane.
  • concentration of stress can be suppressed in the plane of the first conductive layer 10, and the stress can be relieved more uniformly.
  • the plurality of protrusions 11 may be randomly arranged on the XY plane.
  • the arrangement of the protrusions 11 and the recesses 12 in the first shape is not limited to the above.
  • the plurality of protrusions 11 and the plurality of recesses 12 may be arranged regularly.
  • Regularly arranged also includes the case where the arrangement pitch of the projections, the size of the projections and/or the recesses, etc., are arranged so as to change periodically.
  • the first conductive layer 10 supported by the resin layer 30 has the first shape as described above, and the thickness T of the resin layer 30 is the distance H of the first shape. bigger than Alternatively, the first shape of the first conductive layer 10 is a wavy shape and has an amplitude Am smaller than the thickness T of the resin layer 30 .
  • the stress applied from the first material layer 111 which is the particle layer, to the first conductive layer 10 can be relieved by the deformation of the first conductive layer 10 and the resin layer 30 . Therefore, deterioration such as a decrease in conductivity of the first electrode 110 can be suppressed.
  • the "stress applied from the first material layer to the first conductive layer” as used herein refers to the stress applied to the first conductive layer 10 in the process of forming a particle layer on the first conductive layer 10 (for example, a calendering process), It may include stress applied to the first conductive layer 10 due to expansion and contraction of the particle layer during operation. As will be 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 . As a result, the internal stress of the first conductive layer 10 generated during the formation of the first conductive layer 10 can be reduced, so that the decrease in conductivity caused by the internal stress can be suppressed.
  • the first conductive layer 10 may at least partially have the first shape.
  • a portion of the first conductive layer 10 having the first shape is called a "first region".
  • the first region at least partially overlaps the first material layer 111 in the Z direction.
  • the entire first region may overlap the first material layer 111 in the Z direction. That is, the first shape may be formed over the entire region 100e of the first electrode 110 that overlaps 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 , in an electricity storage device using the first electrode 110 , the expansion and contraction of the first material layer 111 causes the first conductive layer 10 to expand and contract. 1 The stress applied to the conductive layer 10 can be relaxed.
  • the portion of the first conductive layer 10 located in the region 100e may be the first region having the first shape, and the portion located in the tub region 100t may be the flat region.
  • the flat region is, for example, 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 in the Z direction of the inner surface 10b of the first conductive layer 10 is within 5% of the thickness of the first conductive layer 10 in the tub region 100t.
  • the first surface 31 of the resin layer 30 may include a plurality of recessed regions (sometimes referred to as “first recessed regions”) 312 in a cross section parallel to the Z direction.
  • the first surface 31 may include a convex region (sometimes referred to as a “first convex region”) 311 between two adjacent concave regions 312 among the plurality of concave regions 312 .
  • the first surface 31 of the resin layer 30 includes multiple concave regions 312 and multiple convex regions 311 .
  • Each recessed area 312 is a concavely curved area of the first surface 31 in a cross-sectional view, and includes, for example, a "dent" formed in the first surface 31 .
  • each concave region 312 is arranged corresponding to one of the plurality of convex portions 11 of the first conductive layer 10 in the Z direction. “Disposed corresponding to” the convex portion 11 includes the case where each concave region 312 at least partially overlaps the corresponding convex portion 11 when viewed in the Z direction. For example, the most ⁇ Z side point in each concave region 312 may overlap the corresponding convex portion 11 when viewed from the Z direction.
  • the convex region 311 may be a convexly curved region, or may be substantially flat (for example, parallel to the XY plane). Each convex region 311 may be arranged corresponding to one of the plurality of concave portions 12 in the first conductive layer 10 in the Z direction. That is, each convex region 311 may at least partially overlap with one corresponding concave portion 12 when viewed in the Z direction. For example, the point located on the +Z side most in each convex region 311 may overlap with one corresponding concave portion 12 when viewed from the Z direction.
  • the arrangement of the recessed regions 312 on the first surface 31 of the resin layer 30 may be random. Also, the sizes of the recessed regions 312 and the projected regions 311 may not be uniform.
  • the first surface 31 of the resin layer 30 may have, for example, a corrugated shape including a plurality of recessed regions 312.
  • the convex regions 311 and the concave regions 312 may be alternately arranged on the first surface 31 .
  • the “wavy shape” includes, like the wavy shape of the first conductive layer 10 , a shape in which the arrangement of the recessed regions 312 does not have regularity.
  • the first surface 31 may have a wavy shape as a whole, and may have flat portions between the recessed regions 312, for example.
  • a gap may be partially formed between the resin layer 30 and the first conductive layer 10 .
  • another solid layer may be interposed between the resin layer 30 and the first conductive layer 10 .
  • FIG. 5 is a diagram showing a part of the cross section of the first electrode 110, and is a schematic diagram based on a cross-sectional SEM image obtained by observing with a scanning electron microscope (SEM).
  • SEM scanning electron microscope
  • the other particles q1 may be arranged corresponding to the convex portions 11q of the first conductive layer 10, and the convex portions 11q may be arranged corresponding to the concave regions 312q of the resin layer 30.
  • “Correspondingly arranged” includes the case of at least partially overlapping in the Z direction, as described above. As shown, the thickness of the first conductive layer 10 can be smaller at the portion overlapping the particle p1 in the Z direction than at the portions located on both sides thereof. In other words, the thickness of the first conductive layer 10 can be smaller at the protrusions 11p than at the recesses 12 .
  • 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. As shown in FIG.
  • FIG. 6 is a schematic cross-sectional view for explaining the relationship between one particle p1 of the first material layer 111 and the first surfaces 31 of the first conductive layer 10 and the resin layer 30.
  • FIG. 6 in a cross section parallel to the Z direction, at least some of the particles p1 contained in the first material layer 111 are located in the two recesses 12 located on both sides of the protrusion 11p in the first conductive layer 10. located in between.
  • the particles p1 are, for example, active material particles.
  • the particle p1 may or may not be in direct contact with the upper surface of the convex portion 11p.
  • At least part of the protrusion 11p may be located inside one recessed region 312p of the resin layer 30 .
  • the convex portion 11p is in direct contact with the upper surface of the concave region 312p, but it does not have to be in contact.
  • the projections 11p in the first conductive layer 10 receive at least part of the particles p1 contained in the first material layer 111. It can also be said that the first conductive layer 10 is curved so as to be able to receive (accommodate) at least a portion of the particles p1.
  • the concave region 312p in the resin layer 30 receives at least part of the convex portion 11p in the first conductive layer 10. That is, at least a portion of the convex portion 11p is received (accommodated) inside the concave region 312p.
  • Each of the recessed regions 312 may receive at least part of one corresponding protrusion 11 .
  • the particles p1, the first conductive layer 10, and the resin layer 30 have the above relationship, for example, in a battery using the first electrode 110, the particles (for example, active material particles) p1 contained in the first material layer 111
  • the force caused by the expansion and contraction of the first conductive layer 10 can be absorbed by the local deformation of the convex portion 11 of the first conductive layer 10 and the concave region 312 of the resin layer 30 .
  • the entire composite film 100 is greatly deformed, the first conductive layer 10 is significantly thinned, and cracks and breaks are suppressed. Therefore, an increase in the resistance of the first conductive layer 10 can be suppressed.
  • the distance Lb in the X direction between the bottom points 12b of the two recesses 12 located on both sides of the protrusion 11p is 1 times the size of the particle p1 (for example, the maximum width in the X direction). It may be 3 times or less. As an example, when the maximum width Lp in the X direction of the particles p1 of the first material layer 111 is 2 to 3 ⁇ m in a cross section observed with an SEM, the distance Lb may be 4 to 9 ⁇ m.
  • At least one convex portion 11 of the first conductive layer 10 only needs to receive the particles of the first material layer 111, and not all the convex portions 11 need to be arranged corresponding to the particles. .
  • at least one of the concave regions 312 of the resin layer 30 may be arranged corresponding to the convex portion 11 receiving the particles.
  • the concave regions corresponding to the particles and the convex portions may not be formed on the first surface 31 of the resin layer 30.
  • FIG. 7A and 7B are schematic enlarged cross-sectional views showing other examples of the first electrode, showing the vicinity of the interface between the first conductive layer 10 and the resin layer 30.
  • FIG. 7A and 7B are schematic enlarged cross-sectional views showing other examples of the first electrode, showing the vicinity of the interface between the first conductive layer 10 and the resin layer 30.
  • the first electrode 110 has one or more gaps (gap ) g.
  • Each gap g is positioned between two of the plurality of protrusions 11 in a direction orthogonal to the Z direction (here, the X direction).
  • the gap g may contain an air layer.
  • the inside of the gap g may contain other substances such as an electrolyte.
  • the “gap” refers to two vertically adjacent solid layers (“first solid layer” and “second solid layer”) among the plurality of solid layers stacked in the Z direction in the first electrode 110. ) refers to a portion (eg, space) generated by partially separating from each other in the Z direction.
  • the gap g may be an internal space surrounded by the first solid layer and the second solid layer.
  • the first solid layer is the resin layer 30
  • the second solid layer is the first conductive layer 10
  • the resin layer 30 and the first conductive layer 10 are partially separated to form a gap g.
  • the gap g may be arranged between the first conductive layer 10 and the first surface 31 of the resin layer 30 in the Z direction.
  • there is a gap between the other solid layer and the resin layer 30 or the first conductive layer 10. may be provided.
  • two gaps g are arranged between two adjacent convex portions 11 of the first conductive layer 10 .
  • the gap g is, for example, an air layer.
  • Gap g is located between inner surface 10 b of first conductive layer 10 and first surface 31 of resin layer 30 and is in contact with inner surface 10 b and first surface 31 .
  • Gap g may be surrounded by inner surface 10 b and first surface 31 .
  • 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 .
  • the “protrusion in contact with the first surface” includes the case where at least part of the protrusion 11 (for example, the portion including the vertex 11 a of the protrusion 11 ) is in contact with the first surface 31 .
  • the first portion 10X does not contact the first surface 31 .
  • the first portion 10X is arranged between two protrusions 11 that are in contact with the first surface 31 of the resin layer 30 .
  • the gap g may extend across two or more protrusions 11 in a direction perpendicular to the Z direction.
  • the first conductive layer 10 has a convex portion 11i, a convex portion 11j, and a convex portion 11k in this order in the +X direction. Between the convex portions 11i and 11k, the gap g extends in the +X direction from the convex portion 11i side to the convex portion 11k side beyond the convex portion 11j. In this case, the entire portion of the first conductive layer 10 in contact with the gap g becomes one first portion 10X. That is, in the illustrated example, in the first conductive layer 10 , the first portion 10X is located between the two protrusions 11i and 11k that are in contact with the first surface 31 of the resin layer 30 .
  • the gap g is arranged between the first conductive layer 10 and the resin layer 30, the internal stress of the first conductive layer 10 can be reduced. Moreover, the stress applied from the first material layer 111 to the first conductive layer 10 can be more effectively relieved.
  • the inner surface 10b of the first conductive layer 10 is preferably in contact with the gap g. Thereby, the internal stress of the first conductive layer 10 can be reduced more effectively.
  • the expression that the inner surface 10b is in contact with the gap g includes the case where part of the inner surface 10b is part of the surface that defines the gap g. More preferably, the gap g contains an air layer, and the inner surface 10b of the first conductive layer 10 is in contact with the air layer. Thereby, the internal stress of the first conductive layer 10 can be more effectively relaxed.
  • FIG. 8 is a partial cross-sectional view showing still another example of the electrode.
  • another solid layer 70 is provided between the first conductive layer 10 and the resin layer 30 .
  • the gap g may be arranged between the first conductive layer 10 and the solid layer 70, for example.
  • the gap g may be arranged between the solid layer 70 and the resin layer 30 .
  • the electrode of this embodiment may further have a second conductive layer on the second surface of the resin layer.
  • a second particle layer may be provided on the side of the second conductive layer opposite to the resin layer.
  • Such electrodes can be used, for example, in stacked cells having multiple pairs of positive and negative electrodes.
  • FIG. 9 is a schematic exploded view showing another example of the electrode of this embodiment.
  • FIG. 10 is a schematic cross-sectional view of the electrode shown in FIG. 9, and also shows an enlarged cross-sectional view of a region surrounded by a dotted line in the figure.
  • FIG. 10 is a cross section parallel to the Z direction.
  • the same reference numerals are given to the same components as in FIG. 2, and the description thereof is omitted as appropriate.
  • the first electrode 110A comprises a composite film 100A having a top surface 100a and a bottom surface 100b, a first material layer 111 located on the top surface 100a of the composite film 100A, and a bottom surface 100b of the composite film 100A. and a second material layer 112 . Similar to electrode 110 shown in FIG. 1, first material layer 111 and second material layer 112 may not be provided in tab region 100t of composite film 100A.
  • the composite film 100A includes a resin layer 30, a first conductive layer 10 and a second conductive layer 20.
  • 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 laminated in the Z direction.
  • the first electrode 110A has 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 may be similar to the shape described above with reference to FIG.
  • the first electrode 110A differs from the first electrode 110 shown in FIG. 2 in that it has the second conductive layer 20 and the second material layer 112 on the second surface 32 side of the resin layer 30 .
  • the second conductive layer 20 is located on the second surface 32 side of the resin layer 30 .
  • the second conductive layer 20 may comprise the same conductive material as the first conductive layer 10 .
  • the second conductive layer 20 has an outer surface 20a located on the opposite side of the resin layer 30 and an inner surface 20b located on the resin layer 30 side.
  • the second material layer 112 is located on the opposite side of the second conductive layer 20 to the resin layer 30 . That is, 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 particle layer containing a plurality of particles.
  • the second material layer 112 may contain the same material as the first material layer 111 .
  • the second conductive layer 20 may have a second shape including a plurality of convex portions 21 convexly curved toward the resin layer 30 side. good.
  • the second shape can be a shape similar to the first shape of the first conductive layer 10 . That is, the second conductive layer 20 may further include a plurality of recesses 22 in a cross section parallel to the Z direction.
  • Each concave portion 22 is positioned, for example, between two adjacent convex portions 21 among the plurality of convex portions 21 .
  • Each recess 22 may be curved concavely with respect to the resin layer 30, or may be substantially flat.
  • the distance H in the Z direction from one of the apexes 21a of the two adjacent convex portions 21 to the bottom point 22b of the concave portion 22 is smaller than the thickness T of the resin layer 30.
  • the second shape may be a wavy shape (sometimes referred to as a "second wavy shape").
  • the corrugated shape has an amplitude Am that is smaller than the thickness T of the resin layer 30 . Since the second conductive layer 20 has the second shape, the stress applied from the second material layer 112 to the second conductive layer 20 can be relaxed.
  • the second surface 32 of the resin layer 30 may include a plurality of recessed areas 322 arranged corresponding to the protrusions 21, similar to the first surface 31.
  • Each recessed region 322 is a region curved concavely toward the first surface 31 side (the positive side in the Z direction in the illustrated example).
  • the second surface 32 may further include a plurality of raised regions 321 .
  • Each convex region 321 is positioned, for example, between two adjacent concave regions 322 among the plurality of concave regions 322 .
  • the protruding region 321 may be a region curved in a convex shape toward the first conductive layer 10 side, or may be substantially flat (for example, substantially parallel to the XY plane).
  • Each concave region 322 is arranged corresponding to one of the plurality of convex portions 21 of the second conductive layer 20 in the Z direction.
  • each concave region 322 may at least partially overlap one corresponding convex portion 21 when viewed in the Z direction.
  • the point closest to the first surface 31 (+Z side) in each concave region 322 may overlap the corresponding convex portion 21 when viewed from the Z direction.
  • 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 positioned between two adjacent protrusions 21 among the plurality of protrusions 21 .
  • the positional relationship between the gap g and the second conductive layer 20 and the resin layer 30 can be the same as the relationship between the gap g and the first conductive layer 10 and the resin layer 30 described above with reference to FIGS. 7A and 7B. . Since the first electrode 110A has the gap g between the second conductive layer 20 and the resin layer 30, the internal stress of the second conductive layer 20 can be alleviated. It is possible to suppress the decline in sexuality.
  • the cross-sectional shape of the second conductive layer 20 is not particularly limited.
  • the cross section of the second conductive layer 20 may not have the second shape.
  • the outer surface 20a and the inner surface 20b of the second conductive layer 20 may be substantially flat surfaces.
  • both the first conductive layer 10 and the second conductive layer 20 preferably have convex portions curved toward the resin layer 30 side. Thereby, the stress from the first material layer 111 and the second material layer 112 arranged on both sides of the composite film 100A can be relaxed. Therefore, since deformation and deterioration of the composite film 100A can be suppressed, an increase in electrical resistance of the first electrode 110A can be suppressed.
  • 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 (for example, in the XY plane).
  • the plurality of protrusions 21 having the second shape include a protrusion 21u that at least partially overlaps one of the plurality of protrusions 11 having the first shape, and a plurality of protrusions 21u that at least partially overlap in the Z direction.
  • a convex portion 21v that does not overlap with any of the portions 11 may also be included.
  • the position of the gap g located between the first conductive layer 10 having the first shape and the resin layer 30 and the position of the second conductive layer having the second shape does not have to correspond either.
  • 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 shapes of the conductive layer and the resin layer over the entire XY plane of the composite film. Therefore, the inventor of the present application found parameters that can be obtained by observing a cross section of the electrode parallel to the X direction and that can affect the characteristics of the electrode, and investigated the relationship between the parameters and the characteristics of the electrode.
  • the method of observing the cross section of the electrode is not particularly limited.
  • a cross section parallel to the stacking direction (Z direction) of the electrodes is observed with a scanning electron microscope (SEM).
  • a cross section parallel to the Z direction and a direction perpendicular to the Z direction (hereinafter referred to as "width direction") DW having a predetermined length L is defined as a "unit called a 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 crossing the X direction and the Y direction.
  • the length L should just be 20 micrometers or more. In this specification, the length L is assumed to be 25 ⁇ m. It is preferable to prepare a plurality of observation samples with different width directions DW from one electrode and observe a plurality of unit cross sections.
  • the numerical value of the parameter obtained by observing at least one arbitrary unit cross section should be within a suitable range. It is preferable that the average value of the numerical values of the parameters in the three or more unit cross sections is within a suitable range.
  • the three or more unit cross sections are preferably unit cross sections having different width directions, and may include, for example, two unit cross sections having width directions DW orthogonal to each other. More preferably, the average value of 5 or more unit cross sections is within the preferred range.
  • the electrode structure of the electrode of the present embodiment such as the cross-sectional shape of the conductive layer and the state of the interface between the conductive layer and the resin layer (including the position and shape of the gap), is optimized.
  • the parameters for converting are explained.
  • the preferred ranges of the parameters of the first shape of the first conductive layer and the second shape of the second conductive layer may be the same, and the preferred ranges of the parameters of the first surface and the second surface of the resin layer may be the same. Therefore, hereinafter, the cross-sectional shape of the conductive layer may be described by taking the first shape of the first conductive layer of the first electrode as an example, and the shape of the first surface of the resin layer is taken as an example. shape may be explained.
  • FIG. 11 is a schematic cross-sectional view showing part of a unit cross section of the electrode 110A.
  • a virtual reference plane 31S of either one of the first surface 31 and the second surface 32 (here, the first surface 31) is drawn, and the normal line of the reference plane 31S
  • the direction may be "Z direction".
  • the reference plane 31S may be determined using image analysis software such as "Azo-kun” (registered trademark) manufactured by Asahi Kasei Engineering Corporation, for example.
  • an average plane calculated from the profile of the first surface 31 of the resin layer 30 by analyzing the image of the unit cross section may be set as the reference plane 31S, and the normal direction of the average plane may be set as the Z direction.
  • the reference plane 31S is the total area of the region 35 defined by the reference plane 31S and the portions of the plurality of first surfaces 31 located above the reference plane 31S in the unit cross section, and the reference plane 31S. , the total area of the region 36 defined by the portion of the plurality of first surfaces 31 located below the reference surface 31S may be substantially the same.
  • Thickness T of resin layer 30 The thickness T of the resin layer 30 will be described with reference to FIG.
  • the thickness T of the resin layer 30 can be obtained, for example, as the average distance in the Z direction between the second surface 32 and the first surface 31 of the resin layer 30 in a certain unit cross section.
  • the thickness of the resin layer 30 in the tab region is measured and approximated.
  • the thickness T may be calculated.
  • the thickness of the resin layer 30 in the tab region is greater than the thickness T of the resin layer 30 in the region overlapping the first material layer 111 (the region 100e shown in FIG. 2) (for example, about 1 to 1.1 times).
  • the thickness T of the resin layer 30 is, for example, 3 ⁇ m or more. If the thickness T is 3 ⁇ m or more, the stress applied to the conductive layer can be absorbed more effectively. In addition, strength as a current collector can be ensured. Preferably, the thickness T is 5 ⁇ m or more. On the other hand, from the viewpoint of improving the energy density, the thickness T may be 12 ⁇ m or less, preferably 6 ⁇ m or less.
  • the distance H can be obtained as one of the parameters relating to the height difference in the Z direction of the first shape of the first conductive layer.
  • FIG. 12 is a schematic cross-sectional view showing part of a unit cross section of the first electrode 110.
  • FIG. 12 in a certain unit cross section, distances h1 to hn (where n is 2 or more) in the Z direction between the apex 11a of each protrusion 11 and the bottom points 12b of two recesses 12 adjacent to each side thereof. integer), and the maximum value h (max) of those distances may be taken as the "distance H". More preferably, the maximum value h (max) of the distances h1 to hn is obtained for each of the two or more unit cross sections, and the average value is taken as the "distance H".
  • the distance H is smaller than the thickness T of the resin layer 30 in this embodiment.
  • the stress applied to the first shape of the first conductive layer 10 can be relieved by the resin layer 30 having a sufficient thickness, so that the decrease in conductivity of the first conductive layer 10 can be suppressed.
  • the distance H may be less than half the thickness T of the resin layer 30 .
  • the distance H may be 1/10 or more of the thickness t of the first conductive layer 10, for example.
  • the distance H may be 0.2 ⁇ m or more.
  • 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.
  • the thickness t may be the thickness of the first conductive layer 10 in the tab region.
  • the amplitude Am of the wavy shape can also be obtained from the unit cross section.
  • the amplitude Am is obtained as 1/2 of the distance H, for example.
  • the amplitude Am may be obtained using pixel analysis software.
  • the amplitude Am is smaller than the thickness T of the resin layer 30.
  • the stress applied from the first material layer 111 to the first conductive layer 10 can be effectively reduced.
  • the amplitude Am of the wavy shape of each conductive layer may be smaller than the thickness T.
  • the first conductive layer 10 and the second conductive layer 20 on both sides of the resin layer 30 each have a cross-sectional shape including a plurality of protrusions
  • the first conductive layer 10 and the second conductive layer 20 The distance H of the second conductive layers 20 is preferably less than the thickness T, and more preferably less than half the thickness T, respectively.
  • the distance dm1 and/or the distance dm2 described below are used.
  • the distance dm1 corresponds to the average of the heights of the protrusions included in each unit cross section (also referred to as "protrusion height") d1
  • the distance dm2 corresponds to the depth of the recesses 12 included in each unit cross section ("recesses d2 (also referred to as "depth").
  • FIG. 13 is a diagram showing a part of the cross section of the first electrode, and is a schematic diagram based on a cross-sectional SEM image.
  • FIG. 14 is a schematic diagram showing part of a unit cross section of the first electrode.
  • the convex height d1 can be measured, for example, as follows. As shown in FIGS. 13 and 14, first, in a unit cross section, the bottom point of a concave portion 12n1 located on the ⁇ DW side of one convex portion 11n to be measured on the inner surface of the first conductive layer 10; A line (line segment) f1 is drawn connecting the bottom point of the concave portion 12n2 located on the +DW side of the convex portion 11n. In this example, line f1 is the tangent to the two recesses. Next, the distance between the line f1 and the convex portion 11n is measured in the direction perpendicular to the line f1.
  • the distance d1 between the line f1 and the point n1, which is the farthest point from the line f1 in the convex portion 11n, is defined as the "height of the convex portion".
  • the point n1 can be, for example, the vertex of the convex portion 11n.
  • the recess depth d2 can be measured as follows. As shown in FIGS. 13 and 14, first, in the unit cross section, the vertex of the convex portion 11m1 located on the ⁇ DW side of one concave portion 12m to be measured on the inner surface of the first conductive layer 10, and the concave portion A line f2 connecting 12m with the vertex of the convex portion 11m2 located on the +DWX side is drawn. In this example, line f2 is the tangent to the two protrusions. Next, the distance between the line f2 and the recess 12m is measured in the direction perpendicular to the line f2.
  • the distance d2 between the line f2 and the point m1 which is the farthest in the vertical direction from the line f2 in the recess 12m is defined as the "recess depth".
  • the point m1 can be the bottom point of the recess 12, for example.
  • the height d1 of the convex portion is measured for each of the convex portions 11 included in one or more unit cross sections, and the average value thereof is taken as the distance dm1. Also, for each of the recesses 12 included in one or a plurality of unit cross sections, the recess depth d2 is measured, and the average value is defined as the distance dm2.
  • the height d1 of the protrusion and the depth d2 of the recess measured by the above method are, for example, less than 0.1 ⁇ m (or less than 1/10 of the thickness of the first conductive layer 10) ) value.
  • At least one of the distance m1 and the distance m2 may be obtained as a parameter of the size of the unevenness.
  • the average value of the distance dm1 is, for example, 0.1 ⁇ m or more and 3.0 ⁇ m or less.
  • the distance dm2 is, for example, 0.1 ⁇ m or more and 3.0 ⁇ m or less. If the distance dm1 and/or the distance dm2 is 0.1 ⁇ m or more, stress applied from the first material layer 111 to the first conductive layer 10 can be more effectively relieved.
  • the distance dm1 and/or the distance dm2 are preferably 0.2 ⁇ m or more.
  • the distance dm1 and/or the distance dm2 is 3.0 ⁇ m or less, it is possible to suppress deformation of the electrode and an increase in the resistance of the first conductive layer 10 due to large local deformation of the first conductive layer 10 .
  • the maximum value of the height d1 of the protrusions 11 included in one or more unit cross sections may be, for example, 0.2 ⁇ m or more and 3.0 ⁇ m or less.
  • the maximum value of the depth d2 of the recesses 12 included in one or more unit cross sections may be, for example, 0.2 ⁇ m or more and 3.0 ⁇ m or less.
  • FIG. 15 is a diagrammatic representation of a part of a cross-sectional SEM image of an electrode produced in Examples described later, showing an example of a unit cross section of the width (length) L of the electrode.
  • convex portion 11 only the convex portion whose height d1 is equal to or greater than a predetermined distance is defined as "convex portion 11".
  • the predetermined distance is not limited to 0.1 ⁇ m, and may be 1/10 of the thickness t of the first conductive layer 10, for example.
  • the convex portions a1 to a10 are the convex portions 11 of the first conductive layer 10. do.
  • the convex portions a6 and a9 are fine convex portions with a height d1 of less than 0.1 ⁇ m, so they are not included in the convex portion.
  • a concave portion may be selected, and the concave portion 12 may be one in which the distance d2, which is the depth of the concave portion, is equal to or greater than the predetermined distance.
  • the apex 11a of the convex portion 11 is indicated by a black circle
  • the bottom point 12b of the concave portion 12 is indicated by a white rhombus.
  • the number of projections 11, recesses 12 and recessed regions 312 in a unit cross section will be described with reference to FIG.
  • the density (or arrangement pitch) of the protrusions 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 protrusions in a unit cross section may be used as a parameter in place of the density of protrusions 11 in the first shape. It is also possible to determine the arrangement pitch of the protrusions from the relationship between the number Na of protrusions in the unit cross section and the length (width) L of the unit cross section. Instead of the number Na of protrusions, the number Nb of recesses may be used.
  • the number Na of protrusions 11 in a unit cross section is, for example, 2 or more and 10 or less. If it is 2 or more, for example, the stress applied from the first material layer 111 to the first conductive layer 10 can be more effectively reduced. If it exceeds 10, the width of the protrusions 11 becomes smaller than the particles of the first material layer 111, and it may be difficult to receive the particles. Although it depends on the size of the particles of the first material layer 111, if the number Na of the protrusions 11 is, for example, 2 or more and 10 or less, the distance between the adjacent recesses 12 has a size that facilitates receiving the particles of the first material layer 111.
  • the number Na of protrusions 11 of the first conductive layer 10 is five, and the number Na of protrusions 21 of the second conductive layer 20 is three.
  • the “number of convex portions Na” referred to here is the number of convex portions having a height d1 of 0.1 ⁇ m or more, and does not include convex portions that are significantly smaller than the thickness of the first conductive layer 10 .
  • the number Nb of the recesses 12 in the unit cross section may be obtained.
  • the number Nb of the concave portions 12 is, for example, 2 or more and 10 or less, like the number Na of the convex portions 11 .
  • the number of recessed regions 312 on the first surface 31 of the resin layer 30 is, for example, the same number of protrusions 11 or smaller than the number of protrusions. This is because the deformation of the first conductive layer 10 toward the resin layer may not be followed. Therefore, the number of recessed regions 312 is, for example, 1 or more and 10 or less.
  • the ratio Lm/L of the length Lm is It can be said that it represents the elongation rate in the width direction DW of one conductive layer 10 .
  • the length Lm of the inner surface 10b of the first conductive layer 10 can be calculated by analyzing the unit cross section.
  • the ratio Lm/L is, for example, 1.04 or more and 1.20 or less. If it is 1.04 or more, the stress applied from the first material layer 111 to the first conductive layer 10 can be more effectively relaxed. If it is 1.20 or less, it is possible to suppress an increase in the resistance of the first conductive layer 10 due to the first conductive layer 10 being elongated and thinned.
  • the thickness t of the first conductive layer 10 will be described with reference to FIG. In a unit cross section, the thickness t of the first conductive layer 10 in the Z direction is, for example, 0.3 ⁇ m or more and 1.5 ⁇ m or less. The thickness t is the average distance in the Z direction between the inner surface 10b and the outer surface 10a of the first conductive layer 10 .
  • the thickness t is 0.3 ⁇ m or more, the resistance of the first conductive layer 10 can be kept low. If the first conductive layer 10 is too thick, it is difficult to deform. Therefore, the deformation of the first conductive layer 10 and the resin layer 30 reduces the effect of relieving the stress from the first material layer 111 . If the thickness of the first conductive layer 10 is, for example, 1.5 ⁇ m or less, the first conductive layer 10 is easily deformed. The mitigation effect becomes pronounced. Furthermore, it is possible to reduce the thickness and weight of the composite film 100 as a whole.
  • the thickness t of the first conductive layer 10 may be thinner at the protrusions 11 than at the recesses 12 .
  • the thinnest portion t1min of the first conductive layer 10 may be positioned at any one of the plurality of protrusions 11 in the unit cross section.
  • the thinnest portion t2min of the second conductive layer 20 may be positioned on any one of the multiple protrusions 21 .
  • the thinnest portions t1min and t2min of the first conductive layer 10 and the second conductive layer 20 are preferably 0.3 ⁇ m or more, or 1/2 or more of the thickness tm. Thereby, a decrease in conductivity of the conductive layer can be suppressed.
  • FIG. 16 is a diagram showing a part of the cross section of the first electrode 110A, and is a schematic diagram based on a cross-sectional SEM image.
  • FIG. 17 is a schematic cross-sectional view showing part of the cross section of the first electrode 110A.
  • the maximum distance (height) hg of the gap g in the Z direction and the maximum length of the gap g in the width direction DW (width) wg can be used.
  • the ratio hg/wg between the height hg and the width wg may be used as a parameter representing the cross-sectional shape of the gap g.
  • the periphery (contour) of the gap g is defined by the first surface of the resin layer 30 and the inner surface of the first conductive layer 10 .
  • the gap g is surrounded by the first surface of the resin layer 30 and the inner surface of the first conductive layer 10 .
  • the height hg of the gap g corresponds to the separation distance between the resin layer 30 and the first conductive layer 10 in the Z direction
  • the width wg of the gap g corresponds to the width between the resin layer 30 and the first conductive layer 10. It corresponds to the peel distance in the direction DW.
  • the average height hg of one or more gaps g located between the first conductive layer 10 and the resin layer 30 is greater than 0 and less than or equal to 3 ⁇ m, for example. If the thickness is 3 ⁇ m or less, the first conductive layer 10 can be more reliably supported by the resin layer 30 , so that the conductive layer 10 may be damaged or bent at a portion apart from the resin layer 30 in the first conductive layer 10 . Decrease can be suppressed. Similarly, the average height hg of one or more gaps g located between the second conductive layer 20 and the resin layer 30 is also greater than 0 and less than or equal to 3 ⁇ m, for example.
  • the average ratio hg/wg between the height hg and the width wg of the gap g located between the first conductive layer 10 and the resin layer 30 is 1 or more and 20 or less, for example. be. If it is 1 or more, the internal stress of the first conductive layer 10 can be more effectively relieved by the gap g. If it is 20 or less, the first conductive layer 10 can be more reliably supported by the resin layer 30 . Therefore, stress applied to the first conductive layer 10 can be easily relieved by the resin layer 30 . Similarly, the average of the ratio hg/wg of the 1 or more gaps g located between the second conductive layer 20 and the resin layer 30 is 1 or more and 20 or less, for example.
  • the ratio of the gap g will be described with reference to FIG. From the viewpoint of stress relaxation of the first conductive layer 10, it is preferable that the ratio of the gaps in the composite film 100A, for example, the number density and the area ratio of the gaps when viewed from the Z direction, is at least a predetermined value.
  • the number Ng of the recesses 12 overlapping the gap g in the Z direction among the recesses 12 of the first conductive layer 10 included in the unit cross section is used as a parameter instead of the number density of the gaps.
  • the first conductive layer 10 has one or more recesses 12, and among the one or more recesses 12, the number Ng of the recesses 12 that at least partially overlap the gap g in the Z direction is, for example, 1 or more and 10 It may be below. If it is 1 or more, the internal stress of the first conductive layer 10 can be relaxed more effectively. If it is 10 or less, the first conductive layer 10 can be more reliably supported by the resin layer 30 , and the stress applied to the first conductive layer 10 can be absorbed by the deformation of the resin layer 30 .
  • the number of gaps g is not particularly limited, but may be 3 or more and 10 or less.
  • the first conductive layer 10 and the resin layer 30 are partially in contact with each other (that is, no other layer is interposed between the first conductive layer 10 and the resin layer 30).
  • the number Ng of the recesses 12 described above is the number Ng of the recesses 12 in contact with the gap g.
  • the “recess in contact with the gap” includes a recess in which part or the whole of the recess 12 is separated from the first surface 31 of the resin layer 30 to form a gap g between the first surface 31 and the recess 12 .
  • two gaps g are arranged between the first conductive layer 10 and the resin layer 30 .
  • the number Ng of recesses 12 in contact with the gap g in the first conductive layer 10 is three
  • the number Ng of recesses 22 in contact with the gap g in the second conductive layer 20 is one.
  • the ratio Tw/L of the total 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.
  • the ratio LX/L of the total length LX of the first portion 10X of the first conductive layer 10 contacting the gap g to the length L of the unit cross section may be used.
  • the total length LX is the total length in the width direction DW of one or more first portions 10X included in the unit cross section.
  • Both the ratio Tw/L and the ratio LX/L are, for example, 0.02 or more and 0.5 or less. If it is 0.02 or more, the internal stress of the first conductive layer 10 can be relaxed more effectively. If it is 0.5 or less, the first conductive layer 10 can be more reliably supported by the resin layer 30 , and the stress applied to the first conductive layer 10 can be absorbed by the deformation of the resin layer 30 .
  • Tw/L may be 0.2 or more and 0.5 or less.
  • the stress applied to the conductive layer due to the expansion and contraction of the particle layer accompanying the operation of the electricity storage device is reduced by the conductive layer having the first shape (or the second shape) and the resin layer.
  • the conductive layer having the first shape (or the second shape) and the resin layer can be absorbed by Since the particles of the particle layer can be received by the convex portions of the conductive layer that are convexly curved toward the resin layer side, it is possible to suppress local application of large stress to the conductive layer. As a result, it is possible to suppress deterioration of the electrode such as a decrease in conductivity of the conductive layer.
  • the internal stress generated when forming the conductive layer can be alleviated. Thereby, it is possible to suppress the deterioration of the conductivity of the electrode caused by the internal stress of the conductive layer.
  • the electrode of the present embodiment as the positive electrode or negative electrode of an electricity storage device such as a secondary battery, the rate characteristics of the electricity storage device can be improved. Also, the reliability of the power storage device can be improved.
  • the method for manufacturing the electrode of the present embodiment includes, for example, a step of preparing a laminated film having a resin layer and a conductive layer supported by the resin layer (STEP 1), and forming the conductive layer supported by the resin layer into a predetermined shape. and a step of forming a material layer (here, a particle layer) on the conductive layer supported by the resin layer (STEP 3).
  • STEP 2 and STEP 3 may be performed at the same time.
  • the plurality of particles press the conductive layer under predetermined conditions, thereby reducing the portions of the conductive layer pressed by the particles. It can be curved convexly toward the resin layer side. This is because when the particles press the conductive layer, a local force is applied to the conductive layer in the depth direction, and this local force is absorbed by the local deformation of the conductive layer and the resin layer. This is probably because the conductive layer is plastically deformed.
  • the conductive layer after forming the particle layer has, for example, a first shape (or a second shape) including protrusions corresponding to these particles.
  • the surface of the resin layer may also be deformed with the deformation of the conductive layer.
  • recessed areas may be formed on the surface of the resin layer to receive the protrusions of the conductive layer. If the resin layer cannot sufficiently follow the deformation of the conductive layer, a gap may be formed between the conductive layer and the surface of the resin layer.
  • the shape of the conductive layer and the surface shape of the resin layer are formed by adjusting various conditions.
  • Conditions for adjusting the shape of the conductive layer include, for example, the hardness and thickness of the resin layer, the type of the conductive layer (extensibility and thickness, the type of particles in the particle layer, the powder form of the particle layer, the particle layer Examples include the shape and size of particles after forming (after pressing), pressure conditions and temperature conditions during particle layer formation, etc. By adjusting these conditions, a conductive layer having a predetermined shape can be realized. be.
  • the pressurization conditions are, for example, when the conductive layer is an aluminum layer, the line pressure is 5000 N/cm or more and 30000 N/cm or less, and the feed speed is 5 m/min or more and 30 m. /min or less.
  • the line pressure may be set in the range of 600 N/cm or more and 35000 N/cm or less, and the feed speed may be set in the range of 5 m/min or more and 30 m/min or less.
  • the particle layer may be pressed at room temperature, or at a temperature of, for example, 30° C. or higher and 80° C. or lower (heat press). By performing hot pressing, it becomes easier to deform the conductive layer and the resin layer.
  • the material and thickness of each layer and the formation conditions of the particle layer were selected with emphasis on suppressing deterioration caused by deformation of the current collector during calendering. The same is true in the case of using a composite film as a current collector, and it is considered that manufacturing conditions that intentionally deform the conductive layer are not selected.
  • the material and thickness of each layer and the formation conditions of the particle layer are intentionally set so as to deform the conductive layer and the resin layer into a predetermined shape. Also, conditions may be set to intentionally create a gap inside the electrode. These conditions are related to each other. For example, if the thickness of the conductive layer is different, appropriate pressurization conditions are different.
  • a laminated film including the resin layer 30, the first conductive layer 10 and the second conductive layer 20 is prepared.
  • the laminated film is obtained by forming the first conductive layer 10 on the first surface 31 of the resin layer 30 and forming the second conductive layer 20 on the second surface 32 of the resin layer 30 .
  • the method of forming the first conductive layer 10 and the second conductive layer 20 is not particularly limited, for example, vapor deposition, sputtering, electrolytic plating, electroless plating, or the like may be used.
  • metal foils to be the first conductive layer 10 and the second conductive layer 20 may be attached to the first surface 31 and the second surface 32 of the resin layer 30, respectively.
  • a polyethylene terephthalate film is used as the resin layer 30 .
  • the surface of the resin layer 30 may be substantially flat. Alternatively, it may have surface irregularities for the purpose of enhancing adhesiveness or the like.
  • an aluminum film is used when the first electrode 110A is, for example, the positive electrode of a lithium ion secondary battery.
  • Aluminum films can be formed on both surfaces of the resin layer 30 by vapor deposition or the like.
  • a copper film is used as the first conductive layer 10 and the second conductive layer 20 .
  • a copper film may be formed on the seed layers by electroplating.
  • a laminated film which is a precursor of the composite film, is obtained.
  • FIG. 18 is a diagram showing a cross-sectional shape of a part of the laminated film obtained by the above method, and is a schematic diagram based on a cross-sectional SEM image.
  • the first conductive layer 10 and the second conductive layer 20 of the laminated film 100B may not have curved portions.
  • the upper surface of the laminated film here, the outer surface 10a of the first conductive layer 10
  • the lower surface of the laminated film here, the outer surface 20a of the second conductive layer 20
  • Each conductive layer may have unevenness reflecting the surface shape of the resin layer 30 .
  • a first material layer 111 which is a particle layer
  • a second material layer 112 which is a particle layer
  • a slurry containing an active material, a binder, and a solvent is prepared, and the slurry is applied to each of the upper and lower surfaces of the laminated film.
  • Organic solvents such as methanol, ethanol, propanol, N-methyl-2-pyrrolidone and N,N-dimethylformamide, or water can be used as the solvent.
  • a doctor blade coater, a slit die coater, a bar coater, or the like can be applied to apply the slurry.
  • screen printing or gravure printing may be applied to apply the slurry.
  • slurry is not applied to the entire surface of the laminated film, leaving a region where no slurry is applied.
  • the solvent in the slurry is removed by drying.
  • the first conductive layer 10 and the second conductive layer 20 in the laminated film are curved by appropriately setting conditions such as pressure and temperature during pressurization.
  • the portion of the first conductive layer 10 located between the resin layer 30 and the first material layer 111 is curved by pressure and deformed into the first shape.
  • the portion of the second conductive layer 20 located between the resin layer 30 and the second material layer 112 is curved by pressure and deformed into the second shape.
  • the first conductive layer 10 and the second conductive layer 20 are deformed, 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.
  • the regions of the first conductive layer 10 and the second conductive layer 20 to which the slurry was not applied may not be curved by pressurization. This region may have a substantially flat surface after pressing.
  • the laminated film, the first material layer 111 and the second material layer 112 are cut into a predetermined shape including the region where the slurry is not applied, so that the composite film 100 and the composite film 100 provided on both sides A first electrode 110A having material layers 111 and 112 is obtained.
  • a region of the laminated film to which slurry is not applied becomes a tab region 100t of the composite film 100A.
  • the step of deforming the conductive layer (STEP 2) is performed simultaneously with the step of forming the particle layer (STEP 3), but the step of deforming the conductive layer may be performed separately.
  • the conductive layer is deformed to have the first shape (or the second shape) by processing the laminated film including the conductive layer and the resin layer. A layer of particles may then be formed on the deformed conductive layer.
  • FIG. 19 is a schematic external view showing an example of the configuration of an electricity storage device
  • FIG. 20 is an exploded perspective view showing cells in the electricity storage device shown in FIG.
  • a pouch-type or laminate-type lithium ion secondary battery is exemplified as an electric storage device.
  • the illustrated lithium ion secondary battery is of a single layer, but may be of a laminated type as described later.
  • the positive electrode, separator, and negative electrode that constitute the cell are stacked along the Z direction in the figure.
  • a lithium ion secondary battery 1001 has a cell 2001, a pair of leads 250 and 260 connected to the cell 2001, an exterior body 300 covering the cell 2001, and an electrolyte 290.
  • the cell 2001 includes a first electrode 110 , a second electrode 120 , and a first layer 170 disposed between the first electrode 110 and the second electrode 120 .
  • the first electrode 110 is a positive electrode and the second electrode 120 is a negative electrode.
  • the first layer 170 contains, for example, an insulating material and functions as a separator.
  • cell 2001 is a single layer cell containing a pair of electrodes.
  • the lead 250 is electrically connected to the first electrode 110 of the cell 2001 and the lead 260 is electrically connected to the second electrode 120 of the cell 2001.
  • the lead 250 is connected to the tab region 100t of the composite film 100 of the first electrode 110
  • the lead 260 is connected to the tab region 200t of the composite film 200 of the second electrode 120.
  • a portion of the lead 250 and a portion of the lead 260 may be located outside the outer package 300 .
  • a portion of the lead 250 that is pulled out to the outside of the package 300 functions as a first terminal (here, a positive electrode terminal) of the lithium ion secondary battery 1001 as an electricity storage device.
  • a portion of the lead 260 that is pulled out of the exterior body 300 functions as a second terminal (here, a negative electrode terminal) of the lithium ion secondary battery 1001 .
  • Electrolyte 290 is further arranged in the space inside the exterior body 300 .
  • Electrolyte 290 is, for example, a non-aqueous electrolyte.
  • seals are provided between the package 300 and the lead 250 and between the package 300 and the lead 260 to prevent leakage of the electrolyte.
  • a stopper for example, a resin film such as polypropylene, not shown in FIG. 19 is arranged.
  • the first electrode 110 has the configuration described above with reference to FIGS.
  • the second electrode 120 includes a composite film 200, similar to the first electrode 110.
  • the second electrode 120 has a composite film 200 and a first material layer 211 overlying the composite film 200 .
  • the first electrode 110 and the second electrode 120 are arranged so that the first material layer 111 and the first material layer 211 face each other with the first layer 170 interposed therebetween.
  • the first material layer 211 is disposed on only a portion of the composite film 200 .
  • the first material layer 211 functions, for example, as an active material layer.
  • Composite film 200 includes a tab region 200t located outside (not overlapping with) first material layer 211 in the Z direction.
  • the second electrode 120 may be a metal current collector such as a metal foil.
  • 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 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. Also, the conductive layer of the composite film 200 may not have the first shape or the second shape in a cross section parallel to the Z direction. For example, the second electrode 120 may have substantially flat inner and outer surfaces. Additionally, the second electrode 120 may not have a composite film. In this case, the second electrode 120 may comprise a metal foil acting as a current collector and a material layer located on the metal foil.
  • FIG. 21 is a schematic external view showing another example of the configuration of the electricity storage device
  • FIG. 22 is an exploded perspective view showing cells extracted from the electricity storage device shown in FIG.
  • a laminated lithium-ion secondary battery is exemplified as an electricity storage device.
  • Components similar to those of the lithium ion secondary battery 1001 shown in FIGS. 19 and 20 are denoted by the same reference numerals, and description thereof is omitted as appropriate.
  • a lithium ion secondary battery 1002 has a cell 2002, a pair of leads 250 and 260 connected to the cell 2002, an exterior body 300 covering the cell 2002, and an electrolyte 290.
  • the cell 2002 includes one or more first electrodes 110A, one or more second electrodes 120A, and one or more first layers 170A.
  • the first electrode 110A, the second electrode 120A and the first layer 170A are all sheet-like.
  • the first electrode 110A, the second electrode 120A and the first layer 170A are laminated along the Z direction in the drawing.
  • the cell 2002 has a structure in which the first electrodes 110A and the second electrodes 120A are alternately laminated via the first layer 170A.
  • the first electrode 110A is a positive electrode and the 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 nineteen first layers 170A, each positioned between first electrode 110A and second electrode 120A.
  • each first electrode 110A can have the structure described above with reference to FIGS.
  • each second electrode 120A like first electrodes 110A, includes a composite film 200A.
  • the second electrode 120A has a composite film 200A, a first material layer 211 located on the top surface of the composite film 200A, and a second material layer 212 located on the bottom surface of the composite film 200A.
  • the first material layer 211 and the second material layer 212 function, for example, as active material layers.
  • Composite film 200A includes tab region 200At located outside first material layer 211 and second material layer 212 in the XY plane (does not overlap first material layer 211 and second material layer 212 in the Z direction).
  • each second electrode 120A may be the same as or different from that of the first electrode 110A. That is, the first material layer 211 and the second material layer 212 of the second electrode 120A are particle layers containing a plurality of particles, and in a cross section parallel to the Z direction, the first conductive layer of the composite film 200A has a first shape. and the second conductive layer may have a second shape. Note that the first material layer 211 and the second material layer 212 of the second electrode 120A may not be particle layers. In addition, in a cross section parallel to the Z direction, the first conductive layer and the second conductive layer of the composite film 200A may not have curved convex portions, for example, have substantially flat inner and outer surfaces. You may Moreover, when the composite film is not applied to the second electrode 120A, the second electrode 120A may include a metal foil functioning as a current collector and material layers located on both sides of the metal foil.
  • Each of the first layers 170A is arranged between the first electrode 110A and the second electrode 120A located closest to the first electrode 110A.
  • the first layer 170A is made of an insulating material such as resin and prevents direct contact between the particle layer of the first electrode 110A and the particle layer of the second electrode 120A.
  • the lead 250 is electrically connected to the multiple first electrodes 110A.
  • the lead 260 is electrically connected to the plurality of second electrodes 120A.
  • the second electrode 120A positioned at the uppermost layer of the laminated structure of the first electrode 110A and the second electrode 120A has the first material layer 211 on its upper surface. may or may not have.
  • the second electrode 120A positioned at the lowest layer of the laminated structure of the first electrode 110A and the second electrode 120A may have the second material layer 212 on its lower surface. , does not have to be.
  • the electricity storage device to which the electrode of the present embodiment can be applied is not limited to the lithium ion secondary battery.
  • the electrode of the present embodiment can also be suitably used, for example, in electric double layer capacitors.
  • one of the first electrode 110A and the second electrode 120A is a positive electrode, and the other is a negative electrode.
  • Each of the positive electrode and the negative electrode can have a composite film in which a conductive layer is provided on the surface of a resin layer, and a material layer supported by the composite film.
  • the composite film used for the positive electrode is referred to as "positive electrode composite film”
  • the resin layer of the positive electrode composite film is referred to as “positive electrode resin layer”
  • the conductive layers (first conductive layer and second conductive layer) of the positive electrode composite film are referred to as "
  • the material layer of the positive electrode is called the "positive electrode conductive layer” and the "positive electrode material layer”.
  • the composite film used for the negative electrode is “negative electrode composite film”
  • the resin layer of the negative electrode composite film is “negative electrode resin layer”
  • the conductive layer (first conductive layer and second conductive layer) of the negative electrode composite film is “negative conductive layer”. layer”
  • the particle layer of the negative electrode is called the "negative electrode material layer”.
  • the positive electrode resin layer of the positive electrode composite film is, for example, a sheet having a thermoplastic resin as a base material.
  • base materials for the positive electrode resin layer include polyester resins, polyamide resins, polyethylene resins, polypropylene resins, polyolefin resins, polystyrene resins, phenol resins, polyurethane resins, acetal resins, cellophane, and ethylene-vinyl alcohol.
  • Copolymer (EVOH), polyethylene terephthalate, polystyrene (PS), polyimide, polyvinyl chloride, and the like can be used.
  • polyolefin resins examples include polyethylene (PE) and polypropylene (PP).
  • the polyolefin-based resin may be an acid-modified polyolefin-based resin.
  • polyester resins include polybutylene terephthalate (PBT) and polyethylene naphthalate.
  • polyamide-based resins include nylon 6, nylon 66 and polymetaxylylene adipamide (MXD6).
  • a uniaxially oriented sheet or biaxially oriented sheet of polyethylene terephthalate, or a biaxially oriented sheet of polypropylene can be suitably used for the positive electrode resin layer.
  • the resin layer 30 may contain at least one of polyethylene terephthalate, polypropylene, polyamide, polyimide, polyethylene, polystyrene, phenolic resin, and epoxy resin, for example.
  • the positive electrode resin layer may be provided in the form of a laminate film containing two or more of the above materials.
  • the positive electrode resin layer may further contain a flameproofing agent or the like.
  • the thickness of the positive electrode resin layer is, for example, 3 ⁇ m or more and 12 ⁇ m or less.
  • the positive electrode resin layer is not limited to the form of a resin film.
  • the positive electrode resin layer may be a nonwoven fabric or porous film containing a thermoplastic resin.
  • the positive electrode resin layer may have a single layer structure, or may have a laminated structure of a plurality of layers.
  • the positive electrode conductive layer is, for example, a conductive film containing aluminum such as an aluminum film or an aluminum alloy film.
  • a conductive film containing aluminum as a main component may be used as the positive electrode conductive layer.
  • "As a main component" includes, for example, a conductive film containing aluminum in an amount of 80% by weight or more. This is advantageous because it facilitates plastic deformation of the positive electrode conductive layer into a predetermined shape by a method to be described later.
  • 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 different from each other. may be
  • the positive electrode conductive layer can be formed by a known semiconductor process. For example, vapor deposition, sputtering, electrolytic plating, electroless plating, etc. may be used.
  • the thickness of each positive electrode conductive layer may be, for example, 50 nm or more and 5 ⁇ m or less, preferably 100 nm or more and 2 ⁇ m or less. More preferably, it is 0.5 ⁇ m or more and 1 ⁇ m or less.
  • the positive electrode conductive layer is not limited to a single layer film. One or both of the positive electrode conductive layers may comprise multiple layers. A protective layer or the like for suppressing oxidation may be further formed on the surface of the positive electrode conductive layer.
  • another solid layer may be interposed between the positive electrode conductive layer and the positive electrode resin layer.
  • the solid layer may be, for example, an undercoat layer or an anchor coat layer to enhance the bonding of the conductive material to the resin layer.
  • the undercoat layer or anchor coat layer may be an organic layer such as acrylic resin or polyolefin resin, or may be a metal layer formed by a sputtering method or the like.
  • the positive electrode material layer contains, for example, a material capable of intercalating and deintercalating 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 further contain a binder, a conductive aid, and the like.
  • An undercoat layer containing carbon may be interposed between the positive electrode composite film and the positive electrode material layer.
  • the particles p1 (FIG. 5) contained in the particle layer may be positive electrode active material particles or conductive particles used as a conductive aid.
  • the particles p1 are positive electrode active material particles.
  • the average particle size of the positive electrode active material used to form the positive electrode material layer is, for example, 1-10 ⁇ m, and the aspect ratio of the particles is, for example, 1-5.
  • secondary particles obtained by granulating such particles may be used to form the positive electrode material layer.
  • the particles of the positive electrode active material may be deformed by calendering or the like when forming the positive electrode material layer. Fractures and cracks may occur in some particles. Therefore, depending 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 may differ from the size of the particles described above.
  • the particle diameter, shape, and the like of the positive electrode active material particles in the positive electrode material layer can be obtained by particle analysis using the above-mentioned "A-zokun".
  • Examples of materials capable of intercalating and deintercalating lithium ions are composite metal oxides containing lithium.
  • Binders in the positive electrode material layer include 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).
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • FEP tetrafluoroethylene-hexafluoropropylene copolymer
  • PFA tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer
  • EFE ethylene-tetrafluoroethylene copolymer
  • PCTFE
  • a vinylidene fluoride-based fluorororubber may be used as the binder.
  • vinylidene fluoride-hexafluoropropylene-based fluororubber VDF-HFP-based fluororubber
  • vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene-based fluororubber VDF-HFP-TFE-based fluororubber
  • vinylidene fluoride- Pentafluoropropylene fluororubber VDF-PFP fluorubber
  • vinylidene fluoride-pentafluoropropylene-tetrafluoroethylene fluororubber VDF-PFP-TFE fluorubber
  • vinylidene fluoride-perfluoromethyl vinyl ether-tetra Fluoroethylene-based fluororubber VDF-PFMVE-TFE-based fluororubber
  • Examples of conductive aids are carbon materials such as carbon powder and carbon nanotubes. Carbon black or the like can be applied to the carbon powder.
  • Other examples of the conductive aid for the positive electrode material layer are metal powders such as nickel, stainless steel and iron, and powders of conductive oxides such as ITO. Two or more of the above materials may be mixed and contained in the positive electrode material layer.
  • (Negative electrode composite film) -Negative electrode resin layer As the material of the negative electrode resin layer of the negative electrode composite film, the materials exemplified as being applicable to the positive electrode resin layer can be applied.
  • the material of the negative electrode resin layer may be the same as that of the positive electrode resin layer, or may be different from each other.
  • the preferable thickness range of the negative electrode resin layer may be the same as the range exemplified for the positive electrode resin layer.
  • Negative electrode conductive layer As a 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 different from each other. may be
  • the negative electrode conductive layer can be formed by a known semiconductor process. For example, vapor deposition, sputtering, electrolytic plating, electroless plating, etc. may be used.
  • the negative electrode conductive layer can be obtained by forming a nickel chromium (NiCr) seed layer on the surface of the negative electrode resin layer by sputtering, and then forming a copper film on the seed layer by electroplating.
  • the negative electrode conductive layer is also not limited to the form of a single layer film.
  • the thickness of the negative electrode conductive layer may be, for example, 50 nm or more and 5 ⁇ m or less, preferably 100 nm or more and 2 ⁇ m or less.
  • An undercoat layer or the like may be interposed between the negative electrode conductive layer and the negative electrode resin layer.
  • a protective layer or the like may be provided on the surface of the negative electrode conductive layer.
  • the negative electrode material layer contains, for example, a material capable of intercalating and deintercalating 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 aid, and the like. An undercoat layer containing carbon may be interposed between the composite film and the negative electrode material layer.
  • Examples of materials that can occlude and release lithium ions are carbon materials such as natural or artificial graphite, carbon nanotubes, non-graphitizable carbon, easily graphitizable carbon (soft carbon), and low-temperature fired carbon.
  • Other examples of materials applicable 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.
  • a silicon-carbon composite may be applied to the negative electrode material layer.
  • the negative electrode material layer is made of an amorphous compound mainly composed of oxide (SiO x (0 ⁇ x ⁇ 2), tin dioxide, etc.), lithium titanate (Li 4 Ti 5 O 12 ) and other particles may be contained.
  • binders and conductive aids applicable to the positive electrode material layer can be applied to the binder and conductive aid of the negative electrode material layer.
  • the binder for the negative electrode material layer cellulose, styrene-butadiene rubber, ethylene-propylene rubber, polyimide resin, polyamide-imide resin, acrylic resin, etc. can also be used in addition to the materials described above.
  • Leads 250 and 260 are plate-shaped members made of a conductive material.
  • the material of the lead on the positive electrode side is, for example, aluminum or an aluminum alloy
  • the material of the lead on the negative electrode side is, for example, nickel or a nickel alloy.
  • Each of the leads 250 and 260 is, for example, a rectangular conductor plate.
  • the shape of leads 250 and leads 260 is not limited to a rectangular plate shape.
  • Various shapes such as a shape that is L-shaped when viewed perpendicularly to the XY plane, a shape that has a through hole, and a shape that is bent in the Z direction can be employed.
  • the first layer 170A is an insulating member that allows passage of lithium ions while preventing an electrical short circuit between the first electrode 110A and the second electrode 120A.
  • the first layer 170A may have a ceramic coating layer on its surface.
  • the thickness of the ceramic coat layer is, for example, in the range of 2 ⁇ m or more and 5 ⁇ m or less.
  • the first layer 170A has a thickness in the range of, for example, 5 ⁇ m or more and 30 ⁇ m or less. More preferably, the thickness of the first layer 170A is in the range of 8 ⁇ m to 20 ⁇ m.
  • an insulating porous material is used for the first layer 170A.
  • porous materials are monolayer or laminate films of polyolefins such as polyethylene, polypropylene, or the group consisting of cellulose, polyesters, polyacrylonitrile, polyimides, polyamides (e.g. aromatic polyamides), polyethylene and polypropylene.
  • the electrolyte is not only between the material layer on the first electrode 110A side and the first layer 170A and between the material layer on the second electrode 120A side and the first layer 170A, but also in the gaps in the first layer 170A. are also placed.
  • Electrolyte 290 for example, a nonaqueous electrolytic solution containing a metal salt such as lithium salt and an organic solvent can be used.
  • Lithium salts include, for example, LiPF6 , LiClO4, LiBF4 , LiCF3SO3 , LiCF3CF2SO3 , LiC ( CF3SO2 ) 3 , LiN ( CF3SO2 ) 2 , LiN ( CF3 CF2SO2 ) 2 , LiN ( CF3SO2 ) ( C4F9SO2 ), LiN ( CF3CF2CO ) 2 , LiBOB and the like can be used.
  • LiPF6 LiClO4, LiBF4 , LiCF3SO3 , LiCF3CF2SO3 , LiC ( CF3SO2 ) 3 , LiN ( CF3SO2 ) 2 , LiN ( CF3 CF2SO2 ) 2 , LiN ( CF3SO2 ) ( C4F9SO2
  • an organic solvent containing cyclic carbonate and chain carbonate can be applied.
  • cyclic carbonates applicable to electrolyte 290 are ethylene carbonate, propylene carbonate, butylene carbonate, and the like.
  • the organic solvent contains at least propylene carbonate as cyclic carbonate.
  • Addition of chain carbonate lowers the kinematic viscosity of the organic solvent. Diethyl carbonate, dimethyl carbonate or ethyl methyl carbonate can be used as the chain carbonate.
  • the volume ratio between cyclic carbonate and linear 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, ⁇ -butyrolactone, 1,2-dimethoxyethane, 1,2-diethoxyethane and the like.
  • the concentration of the electrolyte in the non-aqueous electrolyte is in the range of 0.5 mol/L or more and 2.0 mol/L or less.
  • concentration of the electrolyte 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 the capacity is sufficient during charging and discharging. easy to obtain.
  • the concentration of the electrolyte is 2.0 mol/L or less, lithium ions in the electrolyte can be sufficiently coordinated by the solvent. Sufficient capacity can be easily obtained during discharge.
  • a solid electrolyte layer may also be employed as the electrolyte 290 .
  • Materials for the solid electrolyte layer include perovskite compounds such as La 0.5 Li 0.5 TiO 3 , lysicone compounds such as Li 14 Zn(GeO 4 ) 4 , and garnet compounds such as Li 7 La 3 Zr 2 O 12 .
  • NASICON such as LiZr2 ( PO4 ) 3 , Li1.3Al0.3Ti1.7 ( PO4 ) 3 , Li1.5Al0.5Ge1.5 ( PO4 ) 3 ) type compounds, thio-LISICON type compounds such as Li 3.25 Ge 0.25 P 0.75 S 4 and Li 3 PS 4 , Li 2 SP 2 S 5 , Li 2 O—V 2 O Glass compounds such as 5 -SiO 2 and phosphoric acid compounds such as Li 3 PO 4 , Li 3.5 Si 0.5 P 0.5 O 4 , Li 2.9 PO 3.3 N 0.46 At least one selected from the group can be used.
  • the exterior body 300 is a covering member that holds the cells 2002 and the electrolyte 290 inside.
  • the exterior body 300 has a function of protecting the cell 2002 and the electrolyte 290 from external moisture and the like.
  • exterior body 300 also has a function of preventing leakage of the electrolytic solution to the outside.
  • the exterior body 300 is, for example, a laminated film in which resin films are formed on both sides of a metal foil.
  • a representative example of the metal foil used for the laminated film as the exterior body 300 is aluminum foil.
  • Polymers such as polypropylene, for example, can be applied to the resin that coats the metal foil.
  • the material of the resin film covering the surface of the metal foil on the cell 2002 side (the inner surface of the exterior body 300) and the material of the resin film covering the surface opposite to the cell 2002 may be the same. and may be different.
  • the surface of the metal foil on the cell 2002 side may be coated with polyethylene, polypropylene, or the like, and the opposite surface may be coated with a resin material having a higher melting point, such as polyethylene terephthalate or polyamide (PA). .
  • a resin material having a higher melting point such as polyethylene terephthalate or polyamide (PA).
  • a metal can or the like can be applied in addition to the laminated film.
  • the can may be provided with a valve for discharging gas generated inside.
  • both the positive electrode and the negative electrode may be provided with active material layers on both sides of the composite film as a current collector.
  • the active material layer is positioned on the outermost side of the cell 2002, and an insulating protective layer for ensuring electrical insulation is provided between the can as the exterior body 300 and the cell 2002.
  • a member or the like may be arranged.
  • a material similar to that of the separator 270 can be applied as the material of such a protective member.
  • the exterior body 300 may be a resin covering member formed by curing epoxy resin or the like. In other words, the exterior body 300 may be the resin itself formed by potting.
  • Batteries 1 to 4 are produced in which a composite film containing conductive layers on both sides of a resin layer is applied to the positive electrode. A metal foil is used as a current collector for the negative electrode of each battery. Then, each battery is subjected to a charge/discharge test to evaluate the rate characteristics. After that, the positive electrode is taken out from each battery, and the cross section of the positive electrode is observed.
  • Electrode 1 uses a composite film as a current collector for the positive electrode and a copper foil as a current collector for the negative electrode.
  • a composite film in which an aluminum film is formed as a conductive layer on both sides of a resin layer is prepared.
  • a polyethylene terephthalate sheet having a thickness of 6 ⁇ m is used as the resin layer.
  • an aluminum film is formed by vapor deposition so as to have a thickness of 0.8 ⁇ m to 0.9 ⁇ m to obtain a composite film having a thickness of about 8 ⁇ m.
  • positive electrode active material particle layers are formed as particle layers.
  • LiCoO 2 (LCO) is used as the positive electrode active material.
  • 1 to 3 parts by mass of acetylene black as a conductive aid and 1 to 3 parts by mass of polyvinylidene fluoride (PVDF) as a binder were weighed, and these were mixed to form a positive electrode mixture. get the drug.
  • the positive electrode mixture is dispersed in N-methyl-2-pyrrolidone to obtain a pasty positive electrode mixture coating.
  • This paint is applied to both sides of the composite film so that the coating amount of the positive electrode active material is 10 to 20 mg/cm 2 and dried at 60 to 100° C. to form a positive electrode active material particle layer. Note that the positive electrode active material particle layer is not formed on the portion of the composite film that will become the tab region. After that, pressure molding is performed by a roll press.
  • the roll press conditions (temperature, line pressure, feed rate, etc.) are adjusted according to the material and thickness of the conductive layer, the thickness and softness of the resin layer, etc. so that the desired first shape can be obtained.
  • the linear pressure of the roll press can be set to 10000-30000 N/cm, for example.
  • the temperature of the rollers during roll-pressing (hereinafter abbreviated as "temperature during roll-pressing") can be set to, for example, 25 to 80°C.
  • the linear pressure of roll pressing is set to 25000 N/cm, and the temperature during roll pressing is set to room temperature (for example, 25° C.).
  • Feed speed is set to 10 to 20 m/min.
  • a negative electrode is produced.
  • graphite is used as the negative electrode active material.
  • acetylene black as a conductive aid
  • SBR styrene-butadiene rubber
  • the negative electrode mixture is dispersed in an aqueous solution of carboxymethyl cellulose (CMC) to obtain a pasty negative electrode mixture coating.
  • CMC carboxymethyl cellulose
  • This paint is applied to both sides of an 8 ⁇ m thick electrolytic copper foil so that the coating amount of the negative electrode active material is 7 to 12 mg/cm 2 , and dried at 80 to 110° C. to form a negative electrode active material layer. to form A negative electrode active material layer is not formed on a portion of the copper foil that will be the tab region. Subsequently, the negative electrode active material layer is pressed by roll pressing.
  • the roll press conditions were a line pressure of 10,000 to 30,000 N/cm and a feed rate of 10 to 20 m/min. Thus, a negative electrode is produced.
  • the produced negative electrodes and positive electrodes are alternately laminated via polyethylene separators having a thickness of 12 ⁇ m to produce a laminate including 6 negative electrodes and 5 positive electrodes.
  • a negative electrode lead made of nickel is attached to the tab region of the negative electrode of the laminate, and a positive electrode lead made of aluminum is attached to the tab region of the positive electrode of the laminate by an ultrasonic welding machine.
  • the laminate is inserted into an outer package made of an aluminum laminate film, and the outer package is heat-sealed except for one portion to form an opening.
  • a non-aqueous electrolyte is injected into the exterior body.
  • a non-aqueous electrolyte solution in which 1 M (mol/L) of LiPF 6 was added as a lithium salt in a solvent containing EC (ethylene carbonate)/DEC (diethyl carbonate) at a volume ratio of 3:7.
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • the battery is charged by constant current charging at a charging rate of 0.2C (current value at which charging is completed in 5 hours when constant current charging is performed at 25° C.) until the battery voltage reaches 4.2V.
  • discharge is performed at a constant current discharge rate of 2C (a current value at which charging is completed in 0.5 hours when a constant current charge is performed at 25°C) until the battery voltage reaches 2.8V.
  • each unit cross section is assumed to be 25 ⁇ m.
  • the Z direction of each unit cross section and the apex of the convex portion are specified by the method described above.
  • the image of each unit cross section is analyzed, and the distance H, the number Na of protrusions, and the depth d2 of recesses are measured for each of the first conductive layer and the second conductive layer.
  • the distance H of the five unit cross sections, the number Na of convex portions, and the distance dm2 (average of concave depth d2) are obtained.
  • the presence or absence of a gap g positioned between each conductive layer and the resin layer is examined.
  • Batteries 2, 3, and 4 are produced in the same manner as the battery 1, except for the temperature during roll pressing when forming the positive electrode active material particle layer.
  • the temperature during roll pressing is set to 50° C. for battery 2, 60° C. for battery 3, and 80° C. for battery 4.
  • Table 1 shows the pressing conditions for Batteries 1 to 4.
  • the rate characteristics are measured in the same manner as for battery 1, and then the cross section of the positive electrode is observed.
  • Table 2 also shows the measurement results of the rate characteristics of Batteries 1 to 4 and the measurement results of the distance dm2 between the positive electrodes.
  • the distance dm2 shown in Table 2 is the average value of the recess depth d2 in the first conductive layer and the second conductive layer of the positive electrode of each battery.
  • Batteries 1 to 4 all have high rate characteristics. Further, it can be seen that the distance dm2 between the positive electrodes of batteries 1 to 4 increases as the temperature during roll pressing increases.
  • Tables 3 and 4 show the values of each parameter obtained by observing the cross section of the positive electrode.
  • images of five unit cross sections U2-1 to U2-5 for one positive electrode used in the battery 2 are analyzed.
  • FIG. 15 described above is a diagrammatic representation of the SEM image of the unit cross section U2-1 of the battery 2. As shown in FIG.
  • Batteries 5 to 8 are produced in which a composite film containing conductive layers on both sides of a resin layer is applied to the positive electrode. This differs from Batteries 1 to 4 in that a positive electrode having a gap g between the conductive layer and the resin layer is produced.
  • Batteries 5 to 8 are produced in the same manner as in Battery 1, except for the press conditions (temperature during roll press, line pressure during roll press) when forming the positive electrode active material particle layer.
  • Battery 5 was roll-pressed at a temperature of 50° C. and a linear pressure of 25000 N/cm.
  • Battery 6 was roll-pressed at a temperature of 50° C. and a linear pressure of 30000 N/cm. 40° C., linear pressure of 30,000 N/cm.
  • temperature during roll pressing is set to 25° C.
  • linear pressure is set to 30,000 N/cm.
  • Table 1 The pressing conditions for Batteries 5 to 8 are also summarized in Table 1.
  • the measuring method is the same as the measuring method for the battery 1 .
  • the battery is disassembled, the positive electrode is taken out, a positive electrode observation sample is prepared in the same manner as the battery 1, and the cross section of the positive electrode is observed with an SEM.
  • each unit cross section is assumed to be 25 ⁇ m.
  • the average of the distance H of five unit cross sections, the number Na of protrusions, and the depth d2 of recesses is obtained for the positive electrode of each battery. Also, since the positive electrodes of the batteries 5 to 8 have a gap g inside, the gap g is also analyzed. Specifically, in each unit cross section, for each of the first conductive layer and the second conductive layer, the ratio Tw/L of the total width Tw of the gap g (that is, the ratio of the total length LX of the first portion in contact with the gap g LX/L) and the number Ng of recesses in contact with the gap g are measured, and the average of three unit cross sections is obtained.
  • each unit cross section the height hg and width wg of each gap g located between the first conductive layer and the second conductive layer and the resin layer were measured, and the height of the gap g included in the three unit cross sections was measured. Average the height hg, width wg and hg/wg.
  • Table 5 shows the measurement results of the rate characteristics of batteries 5 to 8 together with the measurement results of distance dm2 and hg/wg.
  • the distance dm2 shown in Table 5 is the average value of the distance d2 in the first conductive layer and the second conductive layer of the positive electrode of each battery.
  • the hg/wg shown in Table 5 is the average hg/wg of the gap between the resin layer and the first and second conductive layers of the positive electrode of each battery.
  • the distance dm2 of batteries 5 to 8 is approximately the same as the distance dm2 (0.25) of electrode 2 described above, but the rate characteristics of batteries 5 to 8 are the rate characteristics of battery 2 (81%). is at least as high as From this, it is confirmed that the rate characteristics can be further improved by providing the gap g between the conductive layer and the resin layer. It is considered that this is because the internal stress of the conductive layer is relieved by the gap g, and the increase in resistance and deterioration of the electrode caused by the internal stress are suppressed.
  • the rate characteristics of the batteries 6 and 7 are higher than those of the other batteries. From this result, it can be seen that the rate characteristics tend to improve as the hg/wg of the gap g increases, but the rate characteristics tend to deteriorate when hg/wg exceeds a certain value. This is probably because the larger the hg/wg (that is, the ratio of the height to the width of the gap), the greater the effect of alleviating the internal stress of the conductive layer. On the other hand, if the hg/wg is too large, the presence of gaps makes it difficult for the resin layer to absorb the stress applied from the particle layer to the conductive layer, which is thought to lower the conductivity of the conductive layer.
  • FIG. 23 is a schematic diagram showing a SEM image of the unit cross section U6-1 of the battery 6 of the example.
  • the recesses in contact with the gaps are denoted by g1 to g8.
  • the power storage device electrodes according to the embodiments of the present disclosure are useful as power sources for various electronic devices, electric motors, and the like.
  • Power storage devices according to embodiments of the present disclosure include, for example, power sources for vehicles typified by bicycles and passenger cars, power sources for communication devices typified by smartphones, power sources for various sensors, unmanned eXtended vehicles ( UxV)) power supply.
  • UxV unmanned eXtended vehicles
  • first conductive layer 10a outer surface 10b of first conductive layer: inner surface 10X of first conductive layer : first portion of first conductive layer 11: convex portion 11a: vertex 12: concave portion 12b: bottom point 20: Second conductive layer 20a: outer surface 20b of second conductive layer: inner surface 21 of second conductive layer: convex portion 21a: peak 22: concave portion 22b: bottom point 30: resin layer 31: first surface 31S of resin layer: Reference surface 32 : Second surface 70 of resin layer : Solid layer 100, 100A, 200, 200A : Composite film 100t, 200t : Tab region 100a : Upper surface 100b of composite film : Lower surface 110, 110A of composite film : First electrode 111 , 112: material layer (particle layer) p1, p2, p3: particles 120, 120A: second electrodes 170, 170A: first layers 211, 212: positive electrode material layers 250, 260: lead 290: electrolyte 300: exterior bodies 311, 3

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CN202180004947.8A CN115428196B (zh) 2021-03-30 2021-03-30 蓄电器件用电极和锂离子二次电池
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JPWO2012001856A1 (ja) * 2010-06-29 2013-08-22 パナソニック株式会社 リチウムイオン二次電池用負極及びリチウムイオン二次電池
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