WO2024181513A1 - 二次電池用電極および二次電池 - Google Patents

二次電池用電極および二次電池 Download PDF

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Publication number
WO2024181513A1
WO2024181513A1 PCT/JP2024/007388 JP2024007388W WO2024181513A1 WO 2024181513 A1 WO2024181513 A1 WO 2024181513A1 JP 2024007388 W JP2024007388 W JP 2024007388W WO 2024181513 A1 WO2024181513 A1 WO 2024181513A1
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Prior art keywords
electrode
positive electrode
secondary battery
current collector
edge portion
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PCT/JP2024/007388
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English (en)
French (fr)
Japanese (ja)
Inventor
毅 千葉
哲 橋本
拓馬 岸
湧基 中井
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Panasonic Energy Co Ltd
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Panasonic Energy Co Ltd
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Priority to CN202480015119.8A priority Critical patent/CN120712654A/zh
Priority to JP2025503977A priority patent/JPWO2024181513A1/ja
Publication of WO2024181513A1 publication Critical patent/WO2024181513A1/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
    • 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
    • H01M10/058—Construction or manufacture
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
    • 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
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/102—Primary casings; Jackets or wrappings characterised by their shape or physical structure
    • H01M50/107—Primary casings; Jackets or wrappings characterised by their shape or physical structure having curved cross-section, e.g. round or elliptic
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/116—Primary casings; Jackets or wrappings characterised by the material
    • H01M50/117—Inorganic material
    • H01M50/119—Metals
    • 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • This disclosure relates to electrodes for secondary batteries and secondary batteries.
  • the secondary battery comprises a wound electrode group as a power generating element, and an electrolyte.
  • the electrode group is formed by winding a pair of strip-shaped electrodes and a separator interposed between the pair of electrodes. At least one of the pair of electrodes comprises a strip-shaped electrode current collector and an electrode mixture layer supported on the electrode current collector.
  • Patent document 1 describes a battery comprising: "a positive electrode having a positive electrode core material and a positive electrode material layer supported on the positive electrode core material; a negative electrode having a negative electrode core material and a negative electrode material layer supported on the negative electrode core material; a separator interposed between the positive electrode and the negative electrode; a non-aqueous electrolyte; a positive electrode current collector electrically connected to the positive electrode core material; and a negative electrode current collector electrically connected to the negative electrode core material; the positive electrode, the negative electrode, and the separator form a columnar wound body.
  • An electrochemical device having a positive electrode core material exposed portion at an end along the longitudinal direction of the positive electrode core material, a negative electrode core material exposed portion at an end along the longitudinal direction of the negative electrode core material, the positive electrode core material exposed portion protruding from one end face of the wound body and welded to the positive electrode current collector plate, the negative electrode core material exposed portion protruding from the other end face of the wound body and welded to the negative electrode current collector plate, and the thickness of the positive electrode core material is greater than the thickness of the negative electrode core material.
  • the electrodes When constructing an electrode group, the electrodes are wound while applying a certain tension to them in order to ensure dimensional accuracy.
  • the tension applied to the electrodes can cause cracks to form starting from the short ends of the electrodes, which can then break them.
  • the dimensions of the electrode may change significantly due to the expansion and contraction of the electrode mixture layer during charging and discharging.
  • One aspect of the present disclosure relates to an electrode for a secondary battery, comprising a strip-shaped electrode current collector and an electrode mixture layer disposed on the electrode current collector, the electrode having a first electrode edge portion including one end of the electrode in the short direction, a second electrode edge portion including the other end of the electrode in the short direction, and an electrode center portion other than the first electrode edge portion and the second electrode edge portion, the tensile strengths of the first electrode edge portion and the second electrode edge portion are each 100 MPa or less, and the tensile strength of the electrode center portion is 150 MPa or more.
  • a secondary battery comprising a power generating element, the power generating element comprising a pair of electrodes, a separator, and an electrolyte, the pair of electrodes being wound with the separator interposed therebetween, and at least one of the pair of electrodes being the above-mentioned secondary battery electrode.
  • FIG. 1 is a schematic cross-sectional view of a secondary battery according to an embodiment
  • FIG. 2 is a schematic plan view of a positive electrode of the secondary battery of FIG. 1
  • FIG. 2 is a schematic plan view of a negative electrode of the secondary battery of FIG. 1 .
  • the secondary battery electrode includes a strip-shaped electrode current collector and an electrode mixture layer disposed on the electrode current collector.
  • the electrode has a first electrode edge portion including one end of the electrode in the short direction, a second electrode edge portion including the other end of the electrode in the short direction, and an electrode center portion other than the first electrode edge portion and the second electrode edge portion.
  • the tensile strength of the first electrode edge portion and the second electrode edge portion is 100 MPa or less.
  • the tensile strength of the electrode center portion is 150 MPa or more.
  • electrode edge portion matters common to the first electrode edge portion and the second electrode edge portion will be simply referred to as "electrode edge portion".
  • the secondary battery electrode is used in a wound electrode group.
  • the secondary battery electrode may be a positive electrode or a negative electrode.
  • Increasing the thickness or flexibility of the electrode current collector is one way of suppressing the occurrence of cracks originating from the short ends of the electrode, which are caused by the tension applied to the electrode during winding.
  • increasing the thickness of the electrode current collector reduces the energy density, which is disadvantageous in terms of increasing capacity.
  • increasing the overall flexibility of the electrode current collector increases the dimensional change of the electrode during charging and discharging, which may cause an internal short circuit.
  • the tensile strength of the electrode edge is set to 100 MPa or less.
  • the flexibility (elongation) of the short-side edge of the electrode is increased, and the generation of cracks originating from the short-side end of the electrode due to the tension applied to the electrode when forming a wound-type electrode group is suppressed, and the breakage of the electrode due to the generation of such cracks is suppressed.
  • the tensile strength of the center of the electrode is set to 150 MPa or more. In this case, deformation (dimensional change) of the electrode during charging and discharging is suppressed, and dimensional change in the short direction of the electrode (axial direction of the electrode group) is suppressed.
  • the electrode current collector is aluminum foil or aluminum alloy foil
  • the electrode is prone to breakage during winding and dimensional changes of the electrode during charging and discharging, so the above-mentioned effect is significantly achieved by setting the tensile strength of the electrode center and edge portions within a specific range.
  • Aluminum foil or aluminum alloy foil is used, for example, as a positive electrode current collector.
  • the tensile strength of the electrode edge reflects the tensile strength of the electrode current collector at the electrode edge, and can also be considered the tensile strength of the electrode current collector at the electrode edge.
  • the tensile strength of the electrode center reflects the tensile strength of the electrode current collector at the electrode center, and can also be considered the tensile strength of the electrode current collector at the electrode center.
  • the tensile strength of the electrode edge can be determined by a tensile test conforming to JIS Z 2241. Specifically, a rectangular sample piece of a specified size is taken from the electrode edge. The size of the test piece is, for example, 120 mm in the longitudinal direction and 8 mm in the transverse direction. The test piece is taken so that the longitudinal direction of the test piece and the longitudinal direction of the electrode are almost the same. The test piece is pulled in the longitudinal direction at a crosshead displacement speed of 5 mm/min, and the maximum stress until the test piece breaks is determined as the tensile strength. The tensile strength of the center of the electrode can be determined in the same manner as for the electrode edge.
  • the test piece is taken from the part other than the current collector exposed part (electrode mixture part). If the entire electrode edge is the current collector exposed part, the test piece is taken from the current collector exposed part.
  • the tensile strength of the electrode edge is preferably 90 MPa or less, and more preferably 85 MPa or less. From the viewpoint of ensuring the strength of the entire electrode, the tensile strength of the electrode edge may be 50 MPa or more or 60 MPa or more.
  • the tensile strengths of the first electrode edge and the second electrode edge may be different from each other, but are preferably approximately equal to each other.
  • approximately equal here means that the ratio of the tensile strength T1 of the first electrode edge to the tensile strength T2 of the second electrode edge: T1/T2 is within the range of 9/11 or more and 11/9 or less.
  • T1/T2 may be 19/21 or more and 21/19 or less.
  • the tensile strength of the central portion of the electrode is preferably 160 MPa or more. From the viewpoint of ensuring flexibility in winding the electrode, the tensile strength of the central portion of the electrode may be, for example, 250 MPa or less.
  • the breaking elongation of each of the first electrode edge portion and the second electrode edge portion is 5% or more.
  • the breaking elongation of the electrode edge portion reflects the breaking elongation of the electrode current collector at the electrode edge portion, and can also be said to be the breaking elongation of the electrode current collector at the electrode edge portion.
  • the breaking elongation rates of the first electrode edge portion and the second electrode edge portion may be different from each other, but are preferably approximately equal to each other.
  • “approximately equal” here means that the ratio of the breaking elongation rate S1 of the first electrode edge portion to the breaking elongation rate S2 of the second electrode edge portion: S1/S2, is within the range of 9/11 or more and 11/9 or less.
  • S1/S2 may be 19/21 or more and 21/19 or less.
  • the widths (lengths in the short direction) of the first electrode edge and the second electrode edge are preferably 8 mm or more and 12 mm or less, respectively. Within the above range, the widths of the first electrode edge and the second electrode edge may be different from each other, but are preferably approximately equal to each other. Note that “approximately equal” here means that the ratio W1/W2 of the width W1 of the first electrode edge to the width W2 of the second electrode edge is in the range of 9/11 or more and 11/9 or less. W1/W2 may be 19/21 or more and 21/19 or less.
  • the ratio of the width W1 (length in the short direction) of the first electrode edge portion to the width W3 (length in the short direction) of the electrode center portion: W1/W3 may be, for example, in the range of 1/11 to 3/7, or in the range of 2/11 to 1/3.
  • the ratio of the width W2 (length in the short direction) of the second electrode edge portion to the width W3 (length in the short direction) of the electrode center portion: W2/W3 may be, for example, in the range of 1/11 to 3/7, or in the range of 2/11 to 1/3.
  • the breaking elongation of the electrode edge can be determined in accordance with JIS Z 2241. Specifically, a tensile test is carried out using a test piece in the same manner as for determining the tensile strength above, and the breaking elongation is determined as the ratio (percentage) of the difference between the gauge length dimension at the time of breakage of the test piece and the gauge length dimension before the test, relative to the gauge length dimension before the test.
  • the first electrode edge portion or the second electrode edge portion may have an exposed portion of the electrode current collector provided along the longitudinal direction of the electrode.
  • the exposed portion may be provided continuously along the longitudinal direction of the electrode, or may be provided intermittently at a plurality of locations along the longitudinal direction of the electrode.
  • the exposed portion is provided from one end or the other end of the short side of the electrode toward the center of the electrode.
  • the short-side end of the electrode on the side having the exposed portion of the electrode current collector has low mechanical strength, and when tension is applied in the longitudinal direction, the stress is non-uniform in the short-side direction, so that when the electrode group is constructed, cracks are likely to occur in the electrode starting from that end. Therefore, by setting the tensile strength of the electrode edge to 100 MPa or less, a significant effect of suppressing cracks can be obtained.
  • the ratio of the width (short-side length) WE of the exposed portion of the electrode current collector to the width (short-side length) W of the electrode edge: WE/W, is, for example, 0.05 or more and 1 or less.
  • the tensile strength of the center of the electrode can be adjusted by appropriately selecting the material and thickness of the base material (metal foil) used for the electrode current collector.
  • the tensile strength of the electrode edge can be adjusted, for example, by heat treating the electrode edge (electrode current collector on the electrode edge) at a predetermined temperature.
  • a metal foil (or alloy foil) having a tensile strength of 150 MPa or more is prepared as an electrode current collector to which the electrode slurry is applied.
  • the tensile strength can be adjusted by the material and thickness of the metal foil.
  • an aluminum foil or an aluminum alloy foil having a thickness of 5 to 20 ⁇ m can be used as the electrode current collector.
  • An electrode slurry containing an electrode mixture and a dispersion medium is applied to the surface of the metal foil, and then dried to form an electrode mixture layer. In this way, an electrode mixture part in which an electrode mixture layer is formed on the surface of the electrode current collector is formed. Then, the electrode mixture part may be rolled using a roller.
  • the exposed portion of the electrode current collector may be formed by not applying the electrode slurry to a part of the electrode current collector, or by scraping off a part of the electrode mixture layer.
  • the electrode mixture layer contains at least the electrode active material.
  • the secondary battery according to the embodiment of the present disclosure includes a power generating element, which includes a pair of strip-shaped electrodes, a separator, and an electrolyte.
  • One of the pair of strip-shaped electrodes is a strip-shaped positive electrode
  • the other of the pair of strip-shaped electrodes is a strip-shaped negative electrode.
  • the pair of electrodes (positive electrode and negative electrode) are wound with the separator interposed therebetween.
  • the secondary battery includes a wound electrode group.
  • the outer shape of the wound electrode group is columnar, and may be, for example, cylindrical. At least one of the pair of electrodes is the secondary battery electrode according to the present disclosure described above.
  • the secondary battery for example, comprises a cylindrical metal case with a bottom that houses a power generating element.
  • the outer diameter of the metal case may be 25 mm or more.
  • An example of such a secondary battery is a secondary battery with a structure shown in FIG. 1.
  • the effect of suppressing electrode breakage can be obtained significantly.
  • the effect of setting the tensile strength of the positive electrode edge to 100 MPa or less can be obtained significantly.
  • Secondary batteries include non-aqueous electrolyte secondary batteries such as lithium ion secondary batteries, lithium metal secondary batteries, and solid-state batteries containing a gel electrolyte or a solid electrolyte.
  • the secondary battery may be a liquid secondary battery containing an electrolytic solution as an electrolyte, or an all-solid-state secondary battery containing a solid electrolyte.
  • FIG. 1 is a schematic cross-sectional view of a secondary battery 10 according to an example of this embodiment.
  • FIG. 2 is a schematic plan view of a positive electrode 110 used in the secondary battery 10 of FIG. 1.
  • FIG. 3 is a schematic plan view of a negative electrode 120 used in the secondary battery 10 of FIG. 1. Note that the positive electrode 110 in FIG. 2 shows an example of an electrode according to an embodiment of the present disclosure, and the electrodes according to the present disclosure are not limited thereto.
  • the secondary battery 10 may be, for example, a lithium ion secondary battery or a lithium secondary battery (lithium metal secondary battery). As shown in FIG. 1, the secondary battery 10 includes a non-polar case 11, a wound electrode group 14, a plurality of positive electrode leads 112 made of a conductor, a positive electrode terminal 16 made of a conductor, an end surface current collector 19 made of a conductor, a negative electrode current collector 22 made of a conductor, and a sealing plate 23.
  • the case 11 is formed in a cylindrical shape with a bottom and an opening at one end (the lower end in FIG. 1).
  • the case 11 is made of metal.
  • a through hole 12 through which a positive electrode terminal 16 is inserted is formed in the center of the bottom (the upper end in FIG. 1) of the case 11.
  • the case 11 contains an electrolyte (not shown) together with an electrode group 14.
  • a recess 13 is formed that is recessed radially inward of the case 11.
  • the electrode group 14 has a positive electrode 110 and a negative electrode 120.
  • the electrode group 14 is a wound type electrode group in which the positive electrode 110 and the negative electrode 120 are wound with a separator (not shown) interposed therebetween.
  • the electrode group 14 is generally cylindrical overall.
  • each of the positive electrode leads 112 is connected to the exposed portion 113b of the positive electrode current collector of the first positive electrode edge portion 113 of the positive electrode 110.
  • the other end of each of the positive electrode leads 112 is provided so as to stand upright from one end face of the electrode group 14.
  • the positive electrode leads 112 are stacked on top of each other and connected to the positive electrode terminal 16 by welding.
  • the number of positive electrode leads 112 is eight, but this is not limited to this. Also, only four of the eight positive electrode leads 112 are shown in FIG. 1.
  • each positive electrode lead 112 is, for example, stainless steel, aluminum, aluminum alloy, nickel, nickel alloy, etc.
  • An insulating member 24 is disposed between the electrode group 14 and the bottom of the case 11 to electrically insulate them from each other.
  • the insulating member 24 is made of, for example, an insulating resin.
  • the insulating member 24 may be attached to the bottom of the case 11.
  • the positive electrode terminal 16 is provided on the opposite side to the electrode group 14, sandwiching multiple positive electrode leads 112 between them.
  • the positive electrode terminal 16 is inserted into the through hole 12 in the bottom of the case 11, penetrating the bottom of the case 11.
  • the positive electrode terminal 16 is made of metal, and a rivet or the like is used.
  • the positive electrode terminal 16 is insulated from the case 11 by a positive electrode gasket 26 made of an insulating material.
  • An insulating plate 25 is placed between the positive electrode terminal 16 and the electrode group 14 to electrically insulate them from each other.
  • the positive electrode terminal 16 has a first terminal member 17 extending from the inside to the outside of the case 11, and a disk-shaped second terminal member 18 joined to the first terminal member 17 and exposed to the outside of the case 11.
  • the first terminal member 17 has a disk-shaped first portion 17a, a hollow cylindrical second portion 17b formed continuously with the first portion 17a and inserted into the through hole 12, and a third portion 17c extending radially outward from the end of the second portion 17b and joined to the second terminal member 18.
  • the first terminal member 17 is welded to the multiple positive electrode leads 112 at the first portion 17a by a laser irradiated in a direction from the first terminal member 17 toward the electrode group 14.
  • the positive electrode terminal 16 is electrically connected to the positive electrode 110 via the multiple positive electrode leads 112 and functions as an external positive electrode terminal of the secondary battery 10.
  • the first terminal member 17 is an example of a terminal member.
  • the positive electrode lead 112 closest to the electrode group 14 has a folded portion 112a formed by folding a part of the positive electrode lead 112 (specifically, a part of the tip side) and on which a part of the laser mark LM by the laser is formed.
  • the folded portion 112a is disposed on the opposite side to the electrode group 14 with the insulating plate 25 in between.
  • the end collector plate 19 is made of metal. There are no particular limitations on the shape of the end collector plate 19, and it may be, for example, generally cross-shaped overall. The end collector plate 19 is electrically connected to the negative electrode 120 of the electrode group 14.
  • the negative current collector 22 is electrically connected to the end current collector 19 via a metal contact plate 21 (which may be formed, for example, in a ring shape). Thus, the negative current collector 22 is electrically connected to the negative electrode 120.
  • the negative current collector 22 and the contact plate 21 may be welded to each other (for example, laser welding).
  • the contact plate 21 and the end current collector 19 may be welded to each other (for example, laser welding).
  • the negative current collector 22 may be directly connected to the end current collector 19. In this case, the contact plate 21 is not necessary.
  • the negative current collector 22 has one or more injection holes 22a for injecting electrolyte into the case 11.
  • the negative current collector 22 is welded (for example, laser welding) to the recess 13 of the case 11 at its outer edge.
  • the case 11 is electrically connected to the negative electrode 120 via the negative current collector 22 and the like.
  • the sealing plate 23 seals the opening of the case 11.
  • the sealing plate 23 is made of metal and has a generally circular plate shape.
  • the sealing plate 23 is insulated from the case 11 by a negative electrode gasket 27.
  • the sealing plate 23 is not electrically connected to either the positive electrode 110 or the negative electrode 120 of the electrode group 14, but this is not limited to this.
  • the sealing plate 23 has an explosion-proof mechanism (not shown) that is activated when the internal pressure of the case 11 exceeds a predetermined value.
  • the positive electrode 110 shown in FIG. 2 is in a state before being wound into the electrode group 14.
  • the arrow Y1 indicates the winding direction of the positive electrode 110 when producing the electrode group 14, and is the longitudinal direction of the positive electrode 110.
  • the arrow Y2 perpendicular to the arrow Y1 indicates the winding axis direction of the positive electrode 110 (i.e., the winding axis direction of the electrode group 14) and is the short side direction of the positive electrode 110.
  • the positive electrode 110 has a first positive electrode edge 113 including one end 110a in the short side direction of the positive electrode 110, a second positive electrode edge 114 including the other end 110b in the short side direction of the positive electrode 110, and a positive electrode center portion 115 other than the first positive electrode edge portion 113 and the second positive electrode edge portion 114.
  • the positive electrode center portion 115 is the region from the positive electrode center side end portion 113a of the first positive electrode edge portion 113 to the positive electrode center side end portion 114a of the second positive electrode edge portion 114.
  • the positive electrode current collector of the positive electrode 110 is, for example, aluminum foil or aluminum alloy foil.
  • the ratio W1/W3 of the width W1 (length in the short direction) of the first positive electrode edge portion 113 to the width W3 (length in the short direction) of the positive electrode center portion 115 may be, for example, in the range of 1/11 to 3/7, or in the range of 2/11 to 1/3.
  • the ratio W2/W3 of the width W2 (length in the short direction) of the second positive electrode edge portion 114 to W3 may also be in the same range as the above W1/W3.
  • the first positive electrode edge portion 113 of the positive electrode 110 has an exposed portion 113b of the positive electrode current collector where the positive electrode mixture layer is not disposed on the positive electrode current collector, and a first positive electrode mixture portion 113c where the positive electrode mixture layer is disposed on the positive electrode current collector.
  • the second positive electrode edge portion 114 has a second positive electrode mixture portion 114c where the positive electrode mixture layer is disposed on the positive electrode current collector.
  • the positive electrode center portion 115 has a third positive electrode mixture portion 115c where the positive electrode mixture layer is disposed on the positive electrode current collector.
  • the exposed portions 113b of the positive electrode current collector are provided at multiple locations (e.g., eight locations) intermittently along the longitudinal direction of the positive electrode current collector.
  • the exposed portions 113b do not have a positive electrode mixture layer from one end 110a of the positive electrode 110 in the lateral direction to the positive electrode central portion 115.
  • each exposed portion 113b of the positive electrode collector in the longitudinal direction may be 1% to 10% of the longitudinal length of the positive electrode collector, and the total length of all exposed portions 113b of the positive electrode collector in the longitudinal direction may be 5% to 30% or 8% to 20% of the longitudinal length of the positive electrode collector.
  • the spacing between adjacent exposed portions 113b of the positive electrode collector be as uniform as possible.
  • the spacing between adjacent exposed portions 113b of the positive electrode collector may be 0.8 ⁇ L/n to 1.2 ⁇ L/n.
  • a tab-shaped positive electrode lead 112 is connected to each exposed portion 113b of the positive electrode collector.
  • the multiple positive electrode leads 112 are bundled together and connected to the first portion 17a of the first terminal member 17.
  • the mass M1 per unit area of the positive electrode mixture layer in the first positive electrode mixture portion 113c may be approximately the same as the mass M3 per unit area of the positive electrode mixture layer in the third positive electrode mixture portion 115c.
  • the ratio of the difference ( ⁇ M) between M1 and M3 to M1 may be, for example, 4% or less, or 3% or less. The same can be said about the mass M2 per unit area of the positive electrode mixture layer in the second positive electrode mixture portion 114c as in the case of M1 above.
  • the negative electrode 120 has a negative electrode edge 123 including one end 120a in the short side direction of the negative electrode 120, and a negative electrode main part 124 other than the negative electrode edge 123.
  • the negative electrode edge 123 faces the first positive electrode edge 113.
  • the negative electrode main part 124 faces the positive electrode main part (the second positive electrode edge 114 and the positive electrode central part 115).
  • the negative electrode main part 124 is the region from the negative electrode central side end 123a of the negative electrode edge 123 to the other end 120b in the short side direction of the negative electrode 120.
  • the ratio of the width (length in the short side direction) of the negative electrode edge 123 to the width (length in the short side direction) of the negative electrode main part 124 is, for example, in the range of 1:15 to 3:4 or 1:12 to 1:7.
  • the negative electrode 120 has an exposed portion 123b of the negative electrode current collector on the other short end 120b side where the negative electrode mixture layer is not disposed on the negative electrode current collector.
  • the exposed portion 123b of the negative electrode current collector is formed along the longitudinal direction of the negative electrode current collector. Therefore, the exposed portion 123b of the negative electrode current collector is exposed at the other end face of the electrode group 14.
  • the exposed portion 123b of the negative electrode current collector is connected to the end face current collector plate 19 by, for example, laser welding.
  • the negative electrode edge portion 123 may be a first negative electrode edge portion having a tensile strength of 100 MPa or less.
  • the exposed portion 123b of the negative electrode current collector may be a second negative electrode edge portion having a tensile strength of 100 MPa or less.
  • the portion of the negative electrode main portion 124 other than the exposed portion 123b of the negative electrode current collector may be a negative electrode central portion having a tensile strength of 150 MPa or more.
  • the positive electrode includes a strip-shaped positive electrode current collector and a positive electrode mixture layer disposed on the positive electrode current collector.
  • the positive electrode mixture layer may be in the form of a film.
  • the positive electrode includes a positive electrode current collector and a positive electrode mixture layer formed (or supported) on the entire or partial surface area of the positive electrode current collector.
  • the positive electrode mixture layer is composed of a positive electrode mixture. Since the positive electrode mixture contains a positive electrode active material as an essential component, the positive electrode mixture layer may also be called a positive electrode active material layer. The positive electrode mixture layer is supported on one or both surfaces of the positive electrode current collector.
  • the positive electrode mixture contains a positive electrode active material as an essential component, and may contain optional components such as a binder, a conductive assistant, and a thickener.
  • the positive electrode active material may be a material that reversibly absorbs and releases lithium ions.
  • the positive electrode active material may be, for example, a lithium-containing transition metal oxide.
  • Representative examples of lithium-containing transition metal oxides include lithium cobalt oxide and lithium nickel oxide, which have a layered, rock-salt crystal structure.
  • the positive electrode mixture layer can be formed, for example, by applying a positive electrode slurry, in which a positive electrode mixture containing particles of the essential positive electrode active material and optional ingredients (binder, conductive additive, etc.) is dispersed in a dispersion medium, to the surface of the positive electrode current collector and then drying. The coating film after drying may be rolled as necessary.
  • the positive electrode mixture layer may be formed on one surface or both surfaces of the positive electrode current collector.
  • NMP N-methyl-2-pyrrolidone
  • a composite oxide containing lithium and a transition metal such as Ni, Co, or Mn can be used.
  • examples include Li a CoO 2 , Li a NiO 2 , Li a MnO 2 , Li a Co b Ni 1-b O 2 , Li a Co b M 1-b O c , Li a Ni 1-b M b O c , Li a Mn 2 O 4 , Li a Mn 2-b M b O 4 , LiMPO 4 , and Li 2 MPO 4 F
  • M is at least one selected from the group consisting of Na, Mg, Sc, Y, Mn, Fe, Co, Ni, Cu, Zn, Al, Cr, Pb, Sb, and B).
  • the value a which indicates the molar ratio of lithium, increases or decreases due to charging and discharging.
  • binders include resin materials, for example, fluororesins such as polytetrafluoroethylene and polyvinylidene fluoride (PVDF); polyolefin resins such as polyethylene and polypropylene; polyamide resins such as aramid resin; polyimide resins such as polyimide and polyamideimide; acrylic resins such as polyacrylic acid, polymethyl acrylate, and ethylene-acrylic acid copolymer; vinyl resins such as polyacrylonitrile and polyvinyl acetate; polyvinylpyrrolidone; polyethersulfone, etc.
  • PVDF polytetrafluoroethylene and polyvinylidene fluoride
  • aramid resin such as aramid resin
  • polyimide resins such as polyimide and polyamideimide
  • acrylic resins such as polyacrylic acid, polymethyl acrylate, and ethylene-acrylic acid copolymer
  • vinyl resins such as polyacrylonitrile and polyvinyl acetate
  • Examples of conductive additives include carbon materials such as graphite, carbon blacks such as acetylene black, carbon fibers (carbon nanotubes (CNT), carbon fibers other than CNT), etc.
  • One type of conductive agent may be used alone, or two or more types may be used in combination.
  • a non-porous conductive substrate such as metal foil
  • a porous conductive substrate such as mesh, net, or punched sheet
  • the material for the positive electrode current collector include stainless steel, aluminum, aluminum alloy, and titanium.
  • the thickness of the positive electrode current collector is preferably 1 to 50 ⁇ m, and more preferably 5 to 20 ⁇ m.
  • the negative electrode includes a strip-shaped negative electrode current collector.
  • the negative electrode may have a negative electrode current collector and a negative electrode mixture layer or a negative electrode active material layer formed (or supported) on the entire or partial area of the surface of the negative electrode current collector.
  • the negative electrode mixture layer or the negative electrode active material layer may be in the form of a film.
  • the negative electrode mixture layer or the negative electrode active material layer is supported on one or both surfaces of the negative electrode current collector.
  • the negative electrode mixture layer is composed of a negative electrode mixture.
  • the negative electrode active material layer is composed of a negative electrode mixture or a negative electrode active material. Since the negative electrode mixture contains a negative electrode active material as an essential component, the negative electrode mixture layer may be called a negative electrode active material layer.
  • the negative electrode active material may be a material that reversibly absorbs and releases lithium ions, may be lithium metal, or may be a lithium alloy.
  • the negative electrode active material layer composed of a material other than the negative electrode mixture is composed of at least one material selected from the group consisting of lithium metal and lithium alloy.
  • the negative electrode mixture layer or the negative electrode active material layer is supported on one or both surfaces of the negative electrode current collector.
  • the negative electrode mixture contains a negative electrode active material as an essential component, and may contain optional components such as a binder, a conductive assistant, and a thickener.
  • a negative electrode mixture layer can be formed, for example, by applying a negative electrode slurry, in which a negative electrode mixture containing particles of the negative electrode active material, which is an essential component, and optional components is dispersed in a dispersion medium, to the surface of the negative electrode current collector and then drying. The coating film after drying may be rolled if necessary.
  • negative electrode active materials include carbon materials, metal materials such as Si and Sn, alloy materials containing Si, Sn, etc., metal compounds containing Si, Sn, etc., and metal oxides containing lithium.
  • metal oxides containing lithium include spinel-type lithium titanium oxide and spinel-type lithium manganese oxide.
  • the carbon material can be graphite, easily graphitized carbon (soft carbon), or non-graphitizable carbon (hard carbon). Of these, graphite is preferred because of its excellent charge/discharge stability and low irreversible capacity.
  • Graphite refers to a carbon material in which the interplanar spacing d002 of the (002) plane measured by X-ray diffraction is, for example, 0.340 nm or less.
  • the crystallite size Lc(002) of graphite measured by X-ray diffraction may be, for example, 5 nm or more, 5 nm or more and 300 nm or less, or 10 nm or more and 200 nm or less.
  • the negative electrode active material may also be a composite material containing Si.
  • the composite material containing Si has high capacity and is suitable as a negative electrode active material.
  • the composite material contains a silicon phase. Silicon can reversibly form an alloy with lithium.
  • the composite material is a material that can reversibly absorb and release lithium ions.
  • the composite material includes a silicon phase and a matrix phase in which the silicon phase is dispersed.
  • the matrix phase may be composed of a material having lithium ion conductivity.
  • the matrix phase includes, for example, at least one type selected from the group consisting of a silicon oxide phase and a carbon phase.
  • the silicon oxide phase contains Si and O, and may further contain a third element other than Si and O.
  • the silicon oxide phase may be composed of SiO2 , may be composed of lithium silicate, or may be composed of both.
  • Lithium silicate can be expressed, for example, as Li2ySiO2 +y (0 ⁇ y ⁇ 2).
  • a composite material in which the silicon oxide phase is composed of SiO2 can be expressed as SiOx (0.5 ⁇ x ⁇ 1.6).
  • the proportion of the composite material in the negative electrode active material is, for example, 1% by mass or more and 20% by mass or less, or may be 3% by mass or more and 15% by mass or less, or may be 3% by mass or more and 10% by mass or less. In this case, it is easy to achieve a good balance between improved cycle characteristics and high capacity.
  • binders include resin materials, such as fluororesins such as polytetrafluoroethylene and polyvinylidene fluoride (PVDF); polyolefin resins such as polyethylene and polypropylene; polyamide resins such as aramid resin; polyimide and polyamideimide; acrylic resins such as polyacrylic acid, polymethyl acrylate, and ethylene-acrylic acid copolymer; vinyl resins such as polyacrylonitrile and polyvinyl acetate; polyvinylpyrrolidone; polyethersulfone; and rubber-like materials such as styrene-butadiene copolymer rubber (SBR).
  • resin materials such as fluororesins such as polytetrafluoroethylene and polyvinylidene fluoride (PVDF); polyolefin resins such as polyethylene and polypropylene; polyamide resins such as aramid resin; polyimide and polyamideimide; acrylic resins such as polyacrylic acid, polymethyl acryl
  • Examples of conductive additives include carbons such as acetylene black, carbon fibers (carbon nanotubes (CNT), carbon fibers other than CNT), metal fibers, and metal powders such as aluminum.
  • the conductive agents may be used alone or in combination of two or more.
  • Thickeners include, for example, carboxymethylcellulose (CMC) and its modified forms (including salts such as the Na salt), cellulose derivatives such as methylcellulose (cellulose ethers, etc.), and saponified polymers having vinyl acetate units such as polyvinyl alcohol.
  • CMC carboxymethylcellulose
  • cellulose derivatives such as methylcellulose (cellulose ethers, etc.)
  • saponified polymers having vinyl acetate units such as polyvinyl alcohol.
  • One type of thickener may be used alone, or two or more types may be used in combination.
  • a non-porous conductive substrate such as metal foil
  • a porous conductive substrate such as mesh, net, or punched sheet
  • the material for the negative electrode current collector include stainless steel, nickel, nickel alloy, copper, and copper alloy.
  • the thickness of the negative electrode current collector is preferably 1 to 50 ⁇ m, and more preferably 5 to 20 ⁇ m.
  • the electrolyte may be a liquid electrolyte (electrolytic solution), a gel electrolyte, or a solid electrolyte.
  • the liquid electrolyte is, for example, an electrolytic solution containing a non-aqueous solvent and a salt dissolved in the non-aqueous solvent.
  • the concentration of the salt in the electrolytic solution is, for example, 0.5 mol/L or more and 2 mol/L or less.
  • the electrolytic solution may contain a known additive.
  • the gel electrolyte contains a salt and a matrix polymer, or a salt, a non-aqueous solvent, and a matrix polymer.
  • a matrix polymer for example, a polymer material that absorbs the non-aqueous solvent and gels is used. Examples of the polymer material include fluororesin, acrylic resin, polyether resin, and polyethylene oxide.
  • solid electrolyte for example, a material known in all-solid-state lithium-ion secondary batteries (e.g., oxide-based solid electrolyte, sulfide-based solid electrolyte, halide-based solid electrolyte, etc.) is used.
  • oxide-based solid electrolyte e.g., oxide-based solid electrolyte, sulfide-based solid electrolyte, halide-based solid electrolyte, etc.
  • a liquid non-aqueous electrolyte is prepared by dissolving a salt in a non-aqueous solvent.
  • the salt is an electrolyte salt that ionizes in the electrolyte, and may include, for example, a lithium salt.
  • the electrolyte may include various additives.
  • the electrolyte is usually used in liquid form, but may also have its fluidity restricted by a gelling agent or the like.
  • a cyclic carbonate ester for example, a cyclic carbonate ester, a chain carbonate ester, a cyclic carboxylate ester, a chain carboxylate ester, etc.
  • the cyclic carbonate ester examples include propylene carbonate (PC), ethylene carbonate (EC), etc.
  • Cyclic carbonate esters having an unsaturated bond, such as vinylene carbonate (VC), can also be used.
  • Cyclic carbonate esters having a fluorine atom such as fluoroethylene carbonate (FEC)
  • the chain carbonate ester include diethyl carbonate (DEC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), etc.
  • Examples of the cyclic carboxylate ester include ⁇ -butyrolactone (GBL), ⁇ -valerolactone (GVL), etc.
  • Examples of the chain carboxylate ester include methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, etc.
  • the non-aqueous solvent may be used alone or in combination of two or more.
  • lithium salt examples include LiClO 4 , LiBF 4 , LiPF 6 , LiAlCl 4 , LiSbF 6 , LiSCN, LiCF 3 SO 3 , LiCF 3 CO 2 , LiAsF 6 , LiB 10 Cl 10 , lower aliphatic lithium carboxylate, LiCl, LiBr, LiI, borates, imide salts, etc.
  • borates examples include lithium bis(1,2-benzenediolate(2-)-O,O')borate, lithium bis(2,3-naphthalenediolate(2-)-O,O')borate, lithium bis(2,2'-biphenyldiolate(2-)-O,O')borate, lithium bis(5-fluoro-2-oleate-1-benzenesulfonic acid-O,O')borate, etc.
  • imide salts include lithium bisfluorosulfonylimide (LiN(FSO 2 ) 2 ), lithium bistrifluoromethanesulfonate imide (LiN(CF 3 SO 2 ) 2 ), lithium trifluoromethanesulfonate nonafluorobutanesulfonate imide (LiN(CF 3 SO 2 )(C 4 F 9 SO 2 )), and lithium bispentafluoroethanesulfonate imide (LiN(C 2 F 5 SO 2 ) 2 ).
  • the lithium salt may be used alone or in combination of two or more.
  • the concentration of the lithium salt in the nonaqueous electrolyte is, for example, 0.5 mol/L or more and 2 mol/L or less.
  • the separator has high ion permeability and has appropriate mechanical strength and insulation properties.
  • a microporous thin film, a woven fabric, a nonwoven fabric, etc. can be used.
  • polyolefin such as polypropylene and polyethylene is preferable.
  • An electrode for a secondary battery A belt-shaped electrode current collector and an electrode mixture layer disposed on the electrode current collector, the electrode has a first electrode edge portion including one end of the electrode in a short side direction, a second electrode edge portion including the other end of the electrode in the short side direction, and an electrode central portion other than the first electrode edge portion and the second electrode edge portion;
  • the tensile strength of the first electrode edge portion and the second electrode edge portion is 100 MPa or less
  • the electrode for a secondary battery wherein the tensile strength of the central portion of the electrode is 150 MPa or more.
  • the first electrode edge portion or the second electrode edge portion has an exposed portion of the electrode current collector that is intermittently provided at a plurality of locations along a longitudinal direction of the electrode, The electrode for a secondary battery according to claim 1, wherein the exposed portion is provided from one or the other end of the electrode in a lateral direction toward a center of the electrode.
  • the electrode for a secondary battery according to claim 1 or 2 wherein the first electrode edge portion and the second electrode edge portion each have a breaking elongation rate of 5% or more.
  • the power generating element includes a pair of electrodes, a separator, and an electrolyte. The pair of electrodes are wound with the separator interposed therebetween, At least one of the pair of electrodes is the secondary battery electrode according to any one of Techniques 1 to 4.
  • Technique 7) a cylindrical metal case with a bottom that houses the power generating element; The secondary battery according to claim 6, wherein the outer diameter of the metal case is 25 mm or more.
  • Examples 1 to 3 and Comparative Example 2 A secondary battery including a wound electrode group was fabricated and the positive electrode of the electrode group was evaluated below.
  • the positive electrode mixture was a mixture of a lithium-containing composite oxide as a positive electrode active material, carbon black as a conductive agent, and polyvinylidene fluoride (PVDF) as a binder. LiNi 0.8 Co 0.1 Mn 0.1 O 2 was used as the lithium-containing composite oxide. In the positive electrode mixture, the mass ratio of the lithium-containing composite oxide to the carbon black and the PVDF was 98:1:1.
  • the positive electrode slurry was applied to both sides of the aluminum foil (thickness 15 ⁇ m) serving as the positive electrode current collector, and the coating was dried and rolled to form a positive electrode mixture layer, obtaining a positive electrode as shown in FIG. 2.
  • the positive electrode slurry was intermittently applied to one end side of the short side of the aluminum foil along the longitudinal direction of the positive electrode current collector with a predetermined thickness, dried, and rolled to form a first positive electrode edge portion having a first positive electrode mixture portion. Eight exposed portions of the positive electrode current collector were provided in the first positive electrode edge portion.
  • the positive electrode slurry was applied to a predetermined thickness on the positive electrode current collector other than the first positive electrode edge portion, dried, and rolled to form a positive electrode main portion.
  • the positive electrode main portion includes a second positive electrode edge portion having a second positive electrode mixture portion, and a positive electrode center portion having a third positive electrode mixture portion.
  • the tensile strength and breaking elongation of the first positive electrode edge portion and the second positive electrode edge portion were set to the tensile strength and breaking elongation of the positive electrode edge portions shown in Table 1, respectively.
  • the tensile strength and breaking elongation were determined by the method described above.
  • the tensile strength of the central portion of the positive electrode that was not heat-treated was 180 MPa.
  • positive electrode leads were attached to each exposed portion of the positive electrode current collector provided on the first positive electrode edge.
  • the width (length in the short direction) of the positive electrode was 65 mm.
  • the widths of the first positive electrode edge and the second positive electrode edge were each set to 10 mm.
  • the width of the central portion of the positive electrode was set to 45 mm.
  • the negative electrode mixture was a mixture of graphite, which was a negative electrode active material, styrene-butadiene copolymer rubber (SBR), which was a binder, and carboxymethyl cellulose (CMC), which was a thickener.
  • SBR styrene-butadiene copolymer rubber
  • CMC carboxymethyl cellulose
  • Anode slurry was applied to both sides of the copper foil (thickness 8 ⁇ m) serving as the anode current collector, and the coating was dried and rolled to form an anode mixture layer, obtaining the anode shown in Figure 3. Specifically, anode slurry was applied to one end of the short side of the copper foil along the longitudinal direction of the anode current collector, and then dried and rolled to form a main anode part having a cathode mixture part. A portion of the other end of the anode current collector was left exposed.
  • the positive electrode and the negative electrode were wound with a separator (a microporous polyethylene film) interposed therebetween to prepare an electrode group.
  • the positive electrode and the negative electrode were arranged so that the edge of the first positive electrode was arranged on one end surface side of the electrode group, and the exposed portion of the negative electrode current collector was arranged on the other end surface side of the electrode group.
  • VC Vinylene carbonate
  • EC ethylene carbonate
  • DMC dimethyl carbonate
  • LiPF 6 LiPF 6 was dissolved to prepare an electrolyte.
  • the content of VC in the entire electrolyte was 5 mass%.
  • the concentration of LiPF 6 in the electrolyte was 1.5 mol/L.
  • a cylindrical lithium ion secondary battery as shown in Fig. 1 was completed.
  • the positive electrode leads were bundled and electrically connected to the first portion of the first terminal member.
  • the exposed portion of the negative electrode current collector was connected to the end surface current collector by laser welding, and the end surface current collector was electrically connected to the negative electrode current collector via a connecting plate.
  • A1 to A3 are batteries of Examples 1 to 3
  • B2 is a battery of Comparative Example 2.
  • Battery B1 of Comparative Example 1 was produced in the same manner as Battery A1 of Example 1, except that in the preparation of the positive electrode, the first positive electrode edge portion and the second positive electrode edge portion were not heat-treated.
  • CT images were taken of the longitudinal section (axial section of the electrode group) of the secondary battery after the charge-discharge cycle, and the short-side length of the positive electrode was determined.
  • the value (mm) obtained by subtracting the initial short-side length of the positive electrode from the short-side length of the positive electrode after the charge-discharge cycle was used to determine the amount of dimensional change of the positive electrode.
  • the amount of dimensional change of the positive electrode was the average value of 10 secondary batteries.
  • Table 1 also shows the breaking elongation of the positive electrode edge.
  • batteries A1 to A5 where the positive electrode edge is 100 MPa or less, breakage of the positive electrode during winding was suppressed. In batteries A1 to A5, where the positive electrode center is 150 MPa or more, dimensional change of the positive electrode during charge/discharge cycles was suppressed.
  • batteries B1 and B2 where the edge of the positive electrode was greater than 100 MPa, the incidence of breakage of the positive electrode during winding increased. In batteries B3 to B5, where the center of the positive electrode was less than 150 MPa, the amount of dimensional change in the positive electrode during charge-discharge cycling increased.
  • Examples 4 to 5> In preparing the positive electrode, the widths of the first positive electrode edge portion and the second positive electrode edge portion were set to the widths of the positive electrode edge portions shown in Table 1. The width of the positive electrode central portion was set to the value shown in Table 1. Except for the above, batteries A4 and A5 of Examples 4 and 5 were prepared and evaluated in the same manner as battery A1 of Example 1. The evaluation results are shown in Table 2. Table 2 also shows the results of secondary battery A1.
  • the secondary battery disclosed herein is useful as a main power source for mobile communication devices, portable electronic devices, electric vehicles, etc.
  • Electrode group 16 Positive electrode terminal 17: First terminal member (terminal member) 17a: First portion 17b: Second portion 17c: Third portion 18: Second terminal member 19: End face current collector plate 21: Connecting plate 22: Negative electrode current collector plate 22a: Injection hole 23: Sealing plate 24: Insulating member 25: Insulating plate 26: Positive electrode gasket 27: Negative electrode gasket LM: Laser mark
  • Positive electrode 110a One end 110b: Other end 112: Positive electrode lead 112a: Folded portion 113: First positive electrode edge portion 113a: Positive electrode central end portion 113b: Positive electrode current collector exposed portion 113c: First positive electrode mixture portion 114: Second positive electrode edge portion 114a: Positive electrode central end portion 114c: Second positive electrode mixture portion 115: Positive electrode central portion 115c: Third positive electrode mixture portion
  • Negative electrode 120a One end 120b: Other end 123: Negative electrode edge portion 123a: Negative electrode central end portion 123b: Negative electrode current collector exposed portion 123c: First negative electrode mixture portion 124: Negative electrode main portion 124c: Second negative electrode mixture portion

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JP2011040371A (ja) * 2009-08-14 2011-02-24 Sb Limotive Co Ltd 二次電池用電極板及びこれを含む二次電池
JP2014053134A (ja) * 2012-09-06 2014-03-20 Sony Corp 二次電池およびその製造方法、ならびに電池パックおよび電動車両
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