Electrode plate for nonaqueous electrolyte secondary battery, and nonaqueous electrolyte secondary battery

Abstract

An electrode plate for a non-aqueous electrolyte secondary battery and a non-aqueous electrolyte secondary battery, the electrode plate having a band-shaped core and a first active material layer formed on at least a first surface of the core, the electrode plate being characterized in that a collector lead is connected to an exposed portion where the core is exposed in a portion of the first surface in the longitudinal direction. The electrode plate for a non-aqueous electrolyte secondary battery has a second active material layer that is disposed adjacent to the exposed portion in a portion of the first surface and that has higher conductivity than the first active material layer.

Description

[0001] This application is a divisional application of an application with an international application date of February 28, 2019 (date of entry into the Chinese national phase: September 27, 2020), an international application number of PCT / JP2019 / 007741 (national application number: 201980022797.6), and an invention name of “Electrode plate for non-aqueous electrolyte secondary battery and non-aqueous electrolyte secondary battery”. Technical Field

[0002] The present disclosure relates to an electrode plate for a nonaqueous electrolyte secondary battery and a nonaqueous electrolyte secondary battery. Background Art

[0003] The cylindrical non-aqueous electrolyte secondary battery has a wound electrode body in which a positive electrode plate and a negative electrode plate as electrode plates are spirally wound with a separator interposed therebetween, and is formed by accommodating the electrode body in a packaging body. Current collecting leads are connected to the positive electrode plate and the negative electrode plate constituting the electrode body, and the positive electrode plate and the negative electrode plate are respectively connected to a sealing body, a packaging can, etc. via the current collecting leads.

[0004] Patent document 1 describes the following technology, that is, when forming a positive electrode plate formed into a strip shape, a composite material mixed with a positive electrode active material and a conductive material, a bonding material, etc. and adjusted to a paste state is sprayed and applied from the first coating nozzle and the second coating nozzle to the collector (core body). At this time, the collector moves continuously along the long side direction, and each coating nozzle has a nozzle separated in the width direction of the collector. Each coating nozzle is configured to be able to control the opening and closing of the nozzle separately and simultaneously. By closing the nozzle of the coating nozzle, a base material portion (core exposed portion) on which the composite material is not coated on the collector is formed.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: International Publication No. 2017 / 077696 Summary of the invention

[0008] As described above, when the positive plate and the negative plate are connected to the collector lead, the connection area between the electrode plate and the collector lead is small, so the collection efficiency decreases, and therefore, the internal resistance of the battery is likely to increase. In the structure described in Patent Document 1, different composite materials are not sprayed from two coating nozzles, and there is room for improvement in terms of reducing the internal resistance of the battery using the obtained electrode plate. On the other hand, it is considered that the internal resistance of the battery is reduced by uniformly increasing the conductivity of the composite material applied to the electrode plate as a whole, but in this case, there is a possibility that the battery capacity is excessively reduced due to the inability of the electrode plate to efficiently perform the battery reaction.

[0009] An object of the present disclosure is to reduce the internal resistance of a battery without excessively reducing the battery capacity in an electrode plate for a nonaqueous electrolyte secondary battery and a nonaqueous electrolyte secondary battery.

[0010] The electrode plate for a non-aqueous electrolyte secondary battery disclosed in the present invention comprises a strip-shaped core and a first active material layer formed on at least the first surface of the core, and a current collecting lead is connected to an exposed portion of the core partially exposed in the long side direction of the first surface, and the electrode plate for a non-aqueous electrolyte secondary battery comprises a second active material layer, and the second active material layer is arranged adjacent to the exposed portion locally on the first surface, and the conductivity of the second active material layer is higher than that of the first active material layer.

[0011] The nonaqueous electrolyte secondary battery of the present disclosure comprises an electrode body formed by winding at least one positive electrode plate and at least one negative electrode plate with a separator interposed therebetween, and a packaging can accommodating the electrode body, wherein at least one of the positive electrode plate and the negative electrode plate is an electrode plate for the nonaqueous electrolyte secondary battery of the present disclosure.

[0012] According to the electrode plate for a nonaqueous electrolyte secondary battery and the nonaqueous electrolyte secondary battery disclosed herein, the internal resistance of the battery can be reduced without excessively reducing the battery capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a cross-sectional view of a nonaqueous electrolyte secondary battery according to an example of the embodiment.

[0014] Figure 2 is from Figure 1 FIG. 1 is a diagram showing a positive electrode plate as an electrode plate for a nonaqueous electrolyte secondary battery according to an embodiment taken out and shown in a developed state.

[0015] Figure 3 yes Figure 2 Enlarged view of part A.

[0016] Figure 4 yes Figure 3 BB cross-sectional view.

[0017] Figure 5 In one embodiment, the direction in which electricity easily flows on the positive electrode plate is shown. Figure 2 The corresponding figure.

[0018] Figure 6 A positive electrode plate as an electrode plate for a non-aqueous electrolyte secondary battery showing another example of the embodiment Figure 2 The corresponding figure.

[0019] Figure 7 yes Figure 6 Enlarged view of part C.

[0020] Figure 8 A positive electrode plate as an electrode plate for a non-aqueous electrolyte secondary battery showing another example of the embodiment Figure 7 The corresponding figure.

[0021] Fig. 9 A positive electrode plate as an electrode plate for a non-aqueous electrolyte secondary battery showing another example of the embodiment Figure 2 The corresponding figure.

[0022] Fig.10 A positive electrode plate as an electrode plate for a non-aqueous electrolyte secondary battery showing another example of the embodiment Figure 2 The corresponding figure.

[0023] Description of Reference Numerals

[0024] 10. Battery; 11. Electrode body; 12. Positive electrode plate; 12a, 12b, 12c, exposed core body; 13. Positive electrode core; 14. First active material layer; 15. Second active material layer; 17, 17a, positive electrode lead; 18. Negative electrode plate; 19, 19a, 19b, 19c, positive electrode plate; 22a, 22b, negative electrode lead; 25. Separator; 31. First band; 32, 32a, second band; 51. Packaging can; 52. Sealing body; 53, 54, insulating plate; 56, protrusion; 57, filter; 58. Lower valve body; 59. Insulating member; 60. Upper valve body; 61. Cover; 62. Gasket. DETAILED DESCRIPTION

[0025] The following is a detailed description of the embodiments of the present disclosure with reference to the accompanying drawings. In the following description, specific shapes, materials, numerical values, directions, etc. are examples for easy understanding of the present disclosure, and can be appropriately changed according to the specifications of the electrode plate for non-aqueous electrolyte secondary battery or the non-aqueous electrolyte secondary battery. In addition, in the following description, the word "roughly" is used to include the meaning of being regarded as substantially the same in addition to the meaning of being used for completely identical situations. And, in the following description, in the case of including multiple embodiments and variations, it is envisaged from the beginning that their characteristic parts are appropriately combined and used.

[0026] Figure 1 1 is a cross-sectional view of a nonaqueous electrolyte secondary battery 10 according to an embodiment. Figure 2 is from Figure 1 FIG. 1 is a diagram showing a positive electrode plate 12 as an electrode plate for a nonaqueous electrolyte secondary battery according to an embodiment taken out and shown in a developed state. Figure 3 yes Figure 2 Enlarged view of part A. Figure 4 yes Figure 3Hereinafter, a nonaqueous electrolyte secondary battery may be described as a battery.

[0027] like Figure 1 As illustrated, the battery 10 has a power generation element and a packaging can 51, and the power generation element includes a wound electrode body 11 and a non-aqueous electrolyte (not shown). The wound electrode body 11 has a separator 25, at least one positive electrode plate 12 and at least one negative electrode plate 18, and the positive electrode plate 12 and the negative electrode plate 18 are spirally wound with the separator 25 between them. The positive electrode plate 12 and the negative electrode plate 18 are equivalent to electrode plates. In addition, the positive electrode plate 12 is equivalent to the first electrode plate, and the negative electrode plate 18 is equivalent to the second electrode plate. In the following description, one axial side of the electrode body 11 is sometimes referred to as "upper" and the other axial side of the electrode body 11 is referred to as "lower". The non-aqueous electrolyte includes a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. The non-aqueous electrolyte is not limited to a liquid electrolyte, and may also be a solid electrolyte using a gel polymer or the like.

[0028] The positive electrode plate 12 has a strip-shaped positive electrode core 13 ( Figure 2 to Figure 4 ) and a positive electrode lead 17 connected to the positive electrode core 13 by being joined thereto. The positive electrode lead 17 is a conductive member for electrically connecting the positive electrode core 13 to the positive terminal, and extends from the upper end of the electrode group to one side (above) of the axial direction α of the electrode body 11. Here, the electrode group means the portion of the electrode body 11 excluding the leads. The positive electrode lead 17 is, for example, provided at the approximate center of the radial direction β of the electrode body 11. Figure 2 to Figure 4 In FIG. 1 , X represents the short side direction of the positive electrode plate 12 and the positive electrode core body 13 , and Y represents the long side direction of the positive electrode plate 12 and the positive electrode core body 13 .

[0029] The negative electrode plate 18 has a strip-shaped negative electrode core and two negative electrode leads 22a and 22b connected to the negative electrode core. Each negative electrode lead 22a and 22b is a conductive member for electrically connecting the negative electrode core and the negative electrode terminal, and extends from the lower end of the electrode group to the other side (downward) of the axial direction α of the electrode body 11. For example, one of the two negative electrode leads 22a and 22b is provided at the end of the winding start side of the electrode body 11, and the other negative electrode lead 22b is provided at the end of the winding end side of the electrode body 11.

[0030] The positive electrode lead 17 and each negative electrode lead 22a, 22b are equivalent to the current collecting lead. The positive electrode lead 17 and each negative electrode lead 22a, 22b are strip-shaped conductive members whose thickness is greater than the thickness of the core body corresponding to them respectively. The thickness of each lead is, for example, 3 to 30 times the thickness of the core body, usually 50μm to 500μm. The constituent material of each lead is not particularly limited. Preferably, the positive electrode lead 17 is composed of a metal with aluminum as the main component, and the negative electrode leads 22a, 22b are composed of a metal with nickel or copper as the main component or a metal including both nickel and copper. In addition, one of the negative electrode leads 22a, 22b may be omitted.

[0031] exist Figure 1 In the example shown, a metal battery case for accommodating an electrode body 11 and a non-aqueous electrolyte is formed by a packaging can 51 and a sealing body 52. ​​Insulating plates 53 and 54 are provided above and below the electrode body 11, respectively. The positive electrode lead 17 extends toward the sealing body 52 through the through hole of the upper insulating plate 53 and is welded to the lower surface of the filter 57 as the bottom plate of the sealing body 52. ​​In the battery 10, the cover 61 as the top plate of the sealing body 52 electrically connected to the filter 57 becomes the positive terminal. On the other hand, the negative electrode lead 22a passes through the through hole of the lower insulating plate 54, and the negative electrode lead 22b passes through the outer side of the lower insulating plate 54, extends toward the bottom side of the packaging can 51, and is welded to the bottom inner surface of the packaging can 51. In the battery 10, the packaging can 51 becomes the negative terminal.

[0032] As described above, the electrode body 11 has a winding structure in which the positive electrode plate 12 and the negative electrode plate 18 are spirally wound with the separator 25 interposed therebetween. The positive electrode plate 12, the negative electrode plate 18, and the separator 25 are all formed into a strip shape and spirally wound, so as to be alternately stacked in the radial direction β of the electrode body 11. In the electrode body 11, the longitudinal direction Y ( Figure 2 ) is the winding direction, and the short side direction X( Figure 2 ) is the axial direction α.

[0033] The packaging can 51 is a metal container in a cylindrical shape with a bottom. A gasket 62 is provided between the packaging can 51 and the sealing body 52 to ensure the airtightness of the battery case. The packaging can 51 has a protrusion 56 that supports the sealing body 52, which is formed by pressing the side surface from the outside. The protrusion 56 is preferably formed in an annular shape along the circumference of the packaging can 51, and the sealing body 52 is supported on the upper surface of the protrusion 56. The sealing body 52 closes the opening of the packaging can 51.

[0034] The sealing body 52 has a filter 57, a lower valve body 58, an insulating member 59, an upper valve body 60, and a cover 61 stacked in sequence from the electrode body 11 side. The components constituting the sealing body 52 have, for example, a disc shape or a ring shape, and the components except the insulating member 59 are electrically connected to each other. The lower valve body 58 and the upper valve body 60 are connected to each other at their respective central portions, and an insulating member 59 is sandwiched between their respective peripheral portions. When the internal pressure of the battery rises due to abnormal heat, for example, the lower valve body 58 ruptures, whereby the upper valve body 60 bulges toward the cover 61 side and separates from the lower valve body 58, thereby cutting off the electrical connection between the two. When the internal pressure rises further, the upper valve body 60 ruptures, and the gas is discharged from the opening 61a of the cover 61.

[0035] The following uses Figure 2 to Figure 4 The positive electrode plate 12 is described in detail. The positive electrode plate 12 includes a strip-shaped positive electrode core 13, a first active material layer 14 as a first positive electrode active material layer formed on the positive electrode core 13, and a second active material layer 15 as a second positive electrode active material layer having a higher conductivity than the first active material layer 14. Figure 2 , Figure 3 In the figure, the first active material layer 14 is shown by the sandy shaded area, and the second active material layer 15 is shown by the oblique grid area. In the present embodiment, the first active material layer 14 is formed on both surfaces of the positive electrode core 13. The positive electrode core 13 is made of, for example, a foil of a metal such as aluminum, or a film having the metal disposed on the surface. A preferred positive electrode core 13 is a foil of a metal having aluminum or an aluminum alloy as a main component. The thickness of the positive electrode core 13 is, for example, 10 μm to 30 μm.

[0036] The first active material layer 14 is formed on the positive electrode core 13. Figure 2 The surface of the paper, namely the first surface 13a ( Figure 4 ) is formed in the entire region of the first range C1 in the short side direction X except for the core exposed portion 12a described later. The first active material layer 14 is also formed on the positive electrode core 13. Figure 2 The back side of the paper, that is, the second side 13b ( Figure 4 ). On the other hand, the second active material layer 15 is formed on the first surface 13a of the positive electrode core 13 in the entire area of ​​the second range C2 different from the first active material layer 14 in the short side direction X, excluding the core exposed portion 12a described later. The second active material layer 15 is not formed on the second surface 13b ( Figure 4 ). In addition, the second active material layer 15 is arranged adjacent to the core exposed portion 12a described later. Thus, the second active material layer 15 is arranged only on a portion of the first surface of the positive electrode core 13 in the short side direction X, specifically, only on the lead-out side end portion of the positive electrode lead 17 in the short side direction X ( Figure 2In addition, the second active material layer 15 is formed along the long side direction Y of the first surface of the positive electrode core body 13. Specifically, the second active material layer 15 is formed along the long side direction Y in the entire area of ​​the positive electrode core body 13 except for the core body exposed portion 12a in the long side direction.

[0037] The first active material layer 14 is most appropriately set from the viewpoint of achieving a good reaction with the negative electrode. The first active material layer 14 includes a positive electrode active material and a binder. The first active material layer 14 may also include a conductive material.

[0038] On the other hand, the second active material layer 15 includes a positive electrode active material and a binder as in the first active material layer 14, and also includes a conductive material. Furthermore, the conductivity of the second active material layer 15 is higher than that of the first active material layer 14. For example, the amount of the conductive material per unit area of ​​the second active material layer 15 is greater than the amount of the conductive material per unit area of ​​the first active material layer 14. For example, when the amount of the conductive material in the first active material layer 14 is 1% or less, the amount of the conductive material in the second active material layer 15 is preferably greater than the amount of the conductive material in the first active material layer 14 and less than 50%.

[0039] It is also possible to have a structure in which the conductive material contained in the second active material layer 15 is fibrous, and the conductive material contained in the first active material layer 14 is non-fibrous granular, instead of the amount of conductive material per unit area of ​​the second active material layer 15 being greater than the amount of conductive material per unit area of ​​the first active material layer 14. For example, the second active material layer 15 may contain carbon nanotubes as a conductive material, and the first active material layer 14 may contain non-fibrous granules such as acetylene black (AB) as a conductive material instead of carbon nanotubes. According to this structure, in the second active material layer 15, the current easily flows toward the positive electrode lead 17. The use of the second active material layer 15 containing a fibrous conductive material is a cause of the increase in cost, but since only a part of the active material layer is set as the second active material layer 15 on the first surface 13a side of the positive electrode plate 12, the increase in cost can be suppressed.

[0040] In addition, the structure may be such that the amount of conductive material per unit area of ​​the second active material layer 15 is greater than the amount of conductive material per unit area of ​​the first active material layer 14, and the conductive material contained in the second active material layer 15 is in a fibrous form, while the conductive material contained in the first active material layer 14 is in a non-fibrous granular form.

[0041] In addition, the ratio of the length of the second range C2 of the second active material layer 15 to the entire length in the short-side direction X of the positive electrode plate 12 is preferably set to about 15%.

[0042] The positive electrode plate 12 is manufactured by coating the first positive composite material paste on both surfaces of the positive electrode core 13 and coating the second positive composite material paste on the first surface 13a of the positive electrode core 13, followed by drying and calendering. At this time, the first positive composite material paste includes a positive electrode active material, a binder, and a solvent having N-methyl-2-pyrrolidone (NMP) or the like and optionally having a conductive material. The second positive composite material paste includes a positive electrode active material, a binder, a conductive material, and a solvent having N-methyl-2-pyrrolidone (NMP) or the like. When coating the first composite material paste and the second composite material paste on the first surface 13a of the positive electrode core 13, as described later, the composite material paste can be ejected from the ejection ports of a plurality of coating nozzles and coated on the first surface 13a.

[0043] As the positive electrode active material, a lithium-containing transition metal oxide containing transition metal elements such as Co, Mn, and Ni can be exemplified. The lithium-containing transition metal oxide is not particularly limited, and is preferably a composite oxide represented by the general formula Li 1+x MO2 (in the formula, -0.2 < x ≤ 0.2, and M includes at least one of Ni, Co, Mn, and Al).

[0044] Examples of the conductive material contained in the first active material layer 14 include, in addition to acetylene black (AB), carbon materials such as carbon black (CB), Ketjen black, and graphite. Examples of the binder include fluororesins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyimide (PI), acrylic resins, and polyolefin resins. In addition, these resins can be used together with carboxymethyl cellulose (CMC) or its salt, polyethylene oxide (PEO), or the like. For these materials, one kind can be used alone, or two or more kinds can be used in combination.

[0045] On the first surface 13a of the positive electrode plate 12, there is provided a core exposure portion 12a ([[]] Figure 3 , Figure 4 ) that exposes the surface of the metal constituting the positive electrode core 13. The core exposure portion 12a is a portion to which the positive electrode lead 17 is connected, and is a portion of the surface of the positive electrode core 13 that is not covered by either the first active material layer 14 or the second active material layer 15. The core exposure portion 12a is formed wider than the width of the positive electrode lead 17. In Figure 2In the example shown, a core exposed portion 12a is provided in the central portion of the positive electrode plate 12 in the long side direction Y, spanning the entire length of the positive electrode core 13 in the short side direction X. The core exposed portion 12a may also be formed at a position close to the end of the positive electrode plate 12 in the long side direction Y, but from the viewpoint of current collection, it is preferably provided at a position approximately equidistant from both ends in the long side direction Y. By connecting the positive electrode lead 17 to the core exposed portion 12a provided in such a position, when the electrode body 11 is wound, the positive electrode lead 17 is arranged to protrude upward from the axial end surface at the radial middle position of the electrode body 11. For example, the core exposed portion 12a is provided by not applying the first positive electrode composite material slurry to a part of the positive electrode core 13 and intermittently applying the second positive electrode composite material slurry.

[0046] like Figure 4 As shown, in the second surface 13b of the positive electrode core 13, the first active material layer 14 is arranged at a position on the side opposite to the core exposed portion 12a in the thickness direction of the positive electrode core 13. On the other hand, it is also possible to have a structure in which no active material layer is arranged at a position on the second surface 13b of the positive electrode core 13 in the thickness direction of the positive electrode core 13 opposite to the core exposed portion 12a where the positive electrode lead 17 is arranged. For example, it is also possible that in the second surface 13b of the positive electrode plate 12 on the side opposite to the positive electrode lead 17, the first active material layer 14 is arranged at a position on the side opposite to the core exposed portion 12a in the width direction ( Figure 4 The same width direction range (by Figure 4 The range indicated by the arrow δ) forms the core exposed portion.

[0047] like Figure 3 As shown, the positive lead 17 is joined to the core exposed portion 12a by laser welding, ultrasonic welding, etc. At this time, the portion of the positive lead 17 extending from the positive core 13 and the portion of the positive lead 17 connected to the positive core 13 are connected by the first tape 31 ( Figure 3 , Figure 4 ) and the second belt 32 covers.

[0048] The first tape 31 is attached to the positive electrode lead 17 in a manner of being wound around the portion of the positive electrode lead 17 that is led out from the positive electrode core 13 and around the portion that overlaps with the positive electrode core 13. As for the second tape 32, the positive electrode plate 12 is sandwiched by two pieces of the second tape 32 from both sides in the thickness direction of the positive electrode plate 12 in a manner of covering the portion of the positive electrode lead 17 that includes the portion wound by the first tape 31 and overlaps with the core exposed portion 12a, a part of the first active material layer 14, and a part of the second active material layer 15. In addition, the two pieces of the second tape 32 are bonded together at the portions protruding from both ends of the short side direction X of the positive electrode plate 12. Thus, the second tape 32 is attached to the positive electrode plate 12 in a manner of covering the core exposed portion 12a. The first tape 31 and the second tape 32 are formed of an insulating material. Each of the tapes 31 and 32 is made of a resin such as polypropylene (PP), for example. The first tape 31 and the second tape 32 can prevent an internal short circuit when the separator 25 between the positive electrode plate 12 and the negative electrode plate 18 is broken. Figure 3 In the embodiment, the first belt 31 and the second belt 32 are transparent, but may be semi-transparent or opaque.

[0049] In the positive electrode plate 12, when the first active material layer 14 and the second active material layer 15 are formed on the positive electrode core 13, the process is as follows. For example, the positive electrode core 13 is moved along the long side direction Y, and the first positive electrode composite material slurry and the second positive electrode composite material slurry are respectively ejected from the ejection ports of the plurality of coating nozzles separately arranged in the first range C1 and the second range C2 in the short side direction X of the positive electrode core 13, and are applied to the respective ranges C1 and C2 of the positive electrode core 13. At this time, the plurality of coating nozzles may eject the composite material slurry at the same position in the long side direction Y of the positive electrode core 13 at the same time, or the plurality of coating nozzles may eject the composite material slurry at positions separated along the long side direction Y of the positive electrode core 13 with the ejection start time changed.

[0050] Back to Figure 1 The negative electrode plate 18 has a strip-shaped negative electrode core and a negative electrode active material layer formed on the negative electrode core. Preferably, the negative electrode active material layer 20 is formed on both sides of the negative electrode core. The negative electrode core is made of, for example, a foil of a metal such as copper, or a film having the metal disposed on the surface. The thickness of the negative electrode core is, for example, 5 μm to 30 μm.

[0051] The negative electrode active material layer is preferably formed on both sides of the negative electrode core body on the entire area of ​​the negative electrode plate 18 except for the exposed portion of the core body. The negative electrode active material layer preferably includes a negative electrode active material and a binder. The negative electrode plate is manufactured by applying a negative electrode composite material slurry including, for example, a negative electrode active material, a binder, and water to both sides of the negative electrode core body, followed by drying and rolling.

[0052] As the negative electrode active material, there is no particular limitation as long as it can reversibly absorb and release lithium ions. For example, carbon materials such as natural graphite and artificial graphite, metals such as Si and Sn alloyed with lithium, or alloys and composite oxides containing these materials can be used. The binder contained in the negative electrode active material layer uses, for example, the same resin as in the case of the positive electrode plate 12. When preparing the negative electrode composite material slurry using an aqueous solvent, styrene-butadiene rubber (SBR), CMC or its salt, polyacrylic acid or its salt, polyvinyl alcohol, etc. can be used. For these materials, one type can be used alone, or two or more types can be used in combination.

[0053] The negative electrode plate 18 is provided with a core exposed portion that exposes the surface of the metal constituting the negative electrode core. The core exposed portion of the negative electrode plate 18 is a portion to which the negative electrode leads 22a and 22b are connected, respectively, and is a portion of the surface of the negative electrode core that is not covered by the negative electrode active material layer. The core exposed portion of the negative electrode plate 18 is a substantially rectangular shape extending long in the width direction of the negative electrode plate 18 and is formed to be wider than the width of each negative electrode lead 22a and 22b.

[0054] In this embodiment, the two negative electrode leads 22a and 22b are joined to the outer peripheral surface of the negative electrode core body by, for example, ultrasonic welding, laser welding, etc. The upper end of each negative electrode lead 22a and 22b is arranged on the core body exposed portion of the negative electrode plate 18, and the lower end extends downward from the lower end of the core body exposed portion.

[0055] The core exposed portion of the negative electrode plate 18 is provided, for example, at both ends of the long side direction of the negative electrode plate 18 (i.e., the end on the winding start side and the end on the winding end side) across the entire width direction of the negative electrode core. The negative electrode lead 22a is provided at the core exposed portion at the end on the winding start side of the negative electrode plate 18, and the negative electrode lead 22b is provided at the core exposed portion at the end on the winding end side of the negative electrode plate 18. In this way, the negative electrode leads 22a and 22b are provided at both ends in the long side direction of the negative electrode plate 18, thereby improving the current collection performance. The arrangement method of the negative electrode lead is not limited to this, and the negative electrode lead 22a may be provided only at the end on the winding start side of the negative electrode plate 18. In this case, it is preferable to set the structure in which the core exposed portion at the end on the winding end side is in direct contact with the inner circumferential surface of the packaging can 51. For example, each core exposed portion is provided by intermittent coating of the negative electrode composite material slurry without coating the negative electrode core locally.

[0056] Similar to the positive electrode plate 12 , a first tape (not shown) is partially attached to the negative electrode leads 22 a and 22 b , and similarly to the positive electrode plate 12 , a second tape (not shown) is partially attached to the negative electrode plate 18 to cover the exposed portion of the core.

[0057] The separator 25 uses a porous sheet having ion permeability and insulation. Specific examples of the porous sheet include microporous films, woven fabrics, nonwoven fabrics, etc. The material of the separator 25 is preferably an olefin resin such as polyethylene and polypropylene. The thickness of the separator 25 is, for example, 10 μm to 50 μm.

[0058] According to the above-mentioned positive electrode plate 12 and battery 10, the second active material layer 15 having higher conductivity than the first active material layer 14 is provided in a part of the first surface 13a of the positive electrode core 13 in the longitudinal direction Y so as to be adjacent to the core exposed portion 12a where the positive electrode core 13 is exposed. As a result, in the first active material layer 14 having lower conductivity than the second active material layer 15, the current easily flows from a position farther from the positive electrode lead 17 to the positive electrode lead 17 via the second active material layer 15 having lower resistance and being nearby. Therefore, the internal resistance of the battery 10 can be reduced. In addition, in order to reduce the internal resistance of the battery 10, the entire first surface 13a of the positive electrode plate 12 except the core exposed portion is not set as the second active material layer having higher conductivity, or the core exposed region without an active material layer is formed to replace the second active material layer. As a result, the positive electrode plate 12 can efficiently perform battery reaction in a large portion, so that in the battery 10 using the positive electrode plate 12, the battery capacity can be prevented from being excessively reduced.

[0059] Figure 5 In one embodiment, the direction in which electricity easily flows on the positive electrode plate 12 is shown. Figure 2 The corresponding figure. Figure 5 In the figure, arrow P schematically shows the direction in which electricity easily flows due to battery reaction between the positive electrode plate 12 and the negative electrode plate. Figure 5 The first active material layer 14 and the second active material layer 15 are on the surface of the paper surface), and the current flows from the first active material layer 14 and the second active material layer 15 toward the positive electrode lead 17 through the battery reaction. At this time, in the first active material layer 14, the current easily flows from a position farther from the positive electrode lead 17 to the positive electrode lead 17 through the second active material layer 15 with lower resistance and nearby. As a result, the resistance is reduced in the current passage path of a large part on the first surface 13a side of the positive electrode plate 12, so the internal resistance of the battery 10 can be reduced. In addition, it is not necessary to increase the exposed portion of the core, so it is possible to prevent the battery capacity from being excessively reduced.

[0060] In addition, there is no need to increase the number of positive electrode leads in order to reduce the internal resistance of the battery 10 , so that the cost can be reduced and the number of parts can be reduced.

[0061] Figure 6 The positive electrode plate 19 as a battery electrode plate showing another example of the embodiment Figure 2 The corresponding figure. Figure 7 yes Figure 6 In the structure of this example, in the first surface 13a of the positive electrode core 13, the end portion ( Figure 6 , Figure 7 The first active material layer 14 is formed over the entire length of the longitudinal direction Y, including the lower end portion of the positive electrode core body 13. In addition, the core exposed portion 12b does not reach the lead-out side end portion ( Figure 6 , Figure 7 The end on the opposite side of the upper end) Figure 6 , Figure 7 The second tape 32a is formed only partially in the short-side direction X in the manner of the lower end of the positive electrode 17a). The positive electrode lead 17a is connected to the core exposed portion 12b. Therefore, the second tape 32a is attached in a manner that includes the connection portion of the positive electrode lead 17a connected to the positive electrode plate 19 and covers only a portion of the positive electrode plate 19 in the short-side direction X.

[0062] Furthermore, the second active material layer 15 is formed in the same range as the core exposed portion 12b in the short side direction X of the positive electrode core 13. In such a structure, when the second active material layer 15 is formed on the positive electrode core 13, the core exposed portion 12b can be formed by intermittent coating using a coating nozzle that ejects the second composite material slurry. At this time, the coating nozzle that ejects the first composite material slurry continuously coats the entire long side direction Y of the positive electrode plate 12.

[0063] According to the above structure, the area of ​​the first active material layer 14 on the first surface 13a of the positive electrode core body 13 can be formed to be smaller than that of the first surface 13a. Figure 1 to Figure 5 The structure is more, so the battery capacity can be increased. In this example, the other structures and functions are the same as Figure 1 to Figure 5 The structure is the same.

[0064] Figure 8 The positive electrode plate 19a as a battery electrode plate showing another example of the embodiment Figure 7 In this example, the structure is Figure 6 , Figure 7Compared with the structure of the present invention, the core exposed portion 12c is larger in the short side direction X, and the core exposed portion 12c is also formed in a part of the short side direction X where the first active material layer 14 is arranged. In such a structure, when the second active material layer 15 is formed on the positive electrode core 13, intermittent coating is performed using a coating nozzle that sprays the second composite material slurry. And the coating nozzle that sprays the first composite material slurry has a structure with a first nozzle and a second nozzle, the first nozzle sprays continuously, and the second nozzle sprays intermittently, and intermittent coating is performed by intermittently spraying the first composite material slurry from the second nozzle. In this way, the core exposed portion 12c can be formed. In this example, the other structures and functions are the same as Figure 1 to Figure 5 structure or Figure 6 , Figure 7 The structure is the same.

[0065] Fig. 9 The positive electrode plate 19b as a battery electrode plate showing another example of the embodiment Figure 2 In the structure of this example, in the first surface 13a of the positive electrode core 13, the second active material layer 15 is formed only in the middle portion in the short side direction X of the positive electrode core 13 in the entire area in the long side direction Y except for the core exposed portion 12a. Along with this, the first active material layer 14 is formed on both sides of the second active material layer 15 in the short side direction X of the first surface 13a of the positive electrode core 13.

[0066] According to the above-described structure, current easily flows from the two first active material layers 14 separated from each other in the short-side direction X via the second active material layer 15 . Fig. 9 The arrow Q indicates the direction in which the current flows easily. At this time, since the length of the short side direction X of each first active material layer 14 is small, it is possible to further reduce the internal resistance of the battery. In this example, the other structures and functions are the same as Figure 1 to Figure 5 The structure is the same.

[0067] Fig.10 The positive electrode plate 19c as a battery electrode plate showing another example of the embodiment Figure 2 In this example, the structure is Figure 1 to Figure 5Different from the structure of the positive electrode core 13, in the first surface of the positive electrode core 13, the second active material layer 15 is formed only on the side end of the core exposed portion 12a in the long side direction Y, on each side of the two sides in the long side direction Y separated by the core exposed portion 12a. Therefore, the second active material layer 15 does not reach the two ends of the positive electrode plate 19c in the long side direction Y. Therefore, the second active material layer 15 is only formed in a local area of ​​the positive electrode core 13 in the long side direction except for the core exposed portion 12a. Along with this, a portion of the first active material layer 14 is formed on the outside of the second active material layer 15 in the positive electrode core 13 in the long side direction Y. In this example, the other structures and functions are the same as Figure 1 to Figure 5 The structure is the same. Fig.10 The structure can also be Fig. 9 The structure is applied to a structure in which the second active material layer 15 is formed only in the middle portion in the short-side direction X of the positive electrode core body 13 on the first surface 13 a of the positive electrode core body 13 .

[0068] The second active material layer 15 is not limited to being formed along the longitudinal direction Y on the first surface of the positive electrode core body 13 , and may be formed inclined with respect to the longitudinal direction of the positive electrode core body 13 , although this is not shown in the figure.

[0069] In addition, the above description describes the case where the second active material layer 15 is formed on the first surface of the positive lead connection side of the positive electrode plate, but it is also possible to form the second active material layer on the first surface of the negative lead connection side of the negative electrode plate together with or instead of the positive electrode plate. In this case, the conductivity of the second active material layer formed on the negative electrode plate is higher than the conductivity of the first active material layer formed on the negative electrode plate. As a result, as in the case of the positive electrode plate, the internal resistance of the battery can be reduced without excessively reducing the battery capacity.

[0070] In addition, the above description takes the case where the second active material layer is formed only on the first surface of the positive electrode lead connection side of the positive electrode plate as an example, but it may also be a structure where the second active material layer is formed only on the second surface on the side opposite to the first surface of the positive electrode lead connection side, or the second active material layer may be formed on both the first surface and the second surface. In addition, in this case, the positive electrode plate and the positive electrode lead may be replaced with a negative electrode plate and a negative electrode lead.

Claims

1. An electrode plate for a non-aqueous electrolyte secondary battery, wherein: The electrode plate for a non-aqueous electrolyte secondary battery comprises a strip-shaped core and a first active material layer formed on at least a first surface of the core, and a current collecting lead is connected to an exposed portion of the core partially exposed in the long side direction of the first surface. The electrode plate for a non-aqueous electrolyte secondary battery has a second active material layer, the second active material layer is arranged adjacent to the exposed portion on a part of the first surface, and the conductivity of the second active material layer is higher than that of the first active material layer. The conductive material included in the second active material layer and the conductive material included in the first active material layer have shapes different from each other.

2. The electrode plate for a non-aqueous electrolyte secondary battery according to claim 1, wherein The conductive material contained in the second active material layer is in a fibrous form. The conductive material contained in the first active material layer is in a non-fibrous particle form.

3. An electrode plate for a non-aqueous electrolyte secondary battery, wherein: The electrode plate for a non-aqueous electrolyte secondary battery comprises a strip-shaped core and a first active material layer formed on at least a first surface of the core, and a current collecting lead is connected to an exposed portion of the core partially exposed in the long side direction of the first surface. The electrode plate for a non-aqueous electrolyte secondary battery has a second active material layer, the second active material layer is arranged adjacent to the exposed portion on a part of the first surface, and the conductivity of the second active material layer is higher than that of the first active material layer. The second active material layer is formed only in the middle portion of the core in the short side direction. The first active material layer is formed on the first surface so as to be adjacent to the second active material layer on both sides in the short side direction of the core body relative to the second active material layer. The exposed portion is formed to be adjacent to the second active material layer in the long side direction and the first active material layer formed on both sides of the second active material layer in the short side direction, respectively. The current collecting lead is connected to a portion of the exposed portion that is adjacent to the second active material layer in the longitudinal direction.

4. A non-aqueous electrolyte secondary battery, comprising: an electrode body formed by winding at least one positive electrode plate and at least one negative electrode plate with a separator interposed therebetween; and The packaging can for housing the electrode body comprises: At least one of the positive electrode plate and the negative electrode plate is the electrode plate for a nonaqueous electrolyte secondary battery according to any one of claims 1 to 3.

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