Cylindrical battery

Abstract

A positive electrode lead (20) is joined between one end (42a) on the winding start side of the positive electrode complexing agent layer (42) and one end (42b) on the winding termination side of the positive electrode complexing agent layer (42) in the alpha direction of the positive electrode (11). In the gamma direction of the negative electrode (12), the negative electrode lead (21) is joined between a first position (A) and a second position (B) in the gamma direction of the negative electrode (12), where the position facing the positive electrode starting end of the negative electrode complexing agent layer (52) is defined as the first position (A), and the center position of the portion facing the positive electrode lead (20) is defined as the second position (B). The negative electrode core (51) is brought into contact with the inner peripheral surface of the outer can.

Description

Technical Field

[0001] The present disclosure relates to cylindrical batteries. Background Art

[0002] Conventionally, as a cylindrical battery, there is a cylindrical battery described in Patent Document 1. This cylindrical battery includes an electrode body, a cylindrical outer can that houses the electrode body, and a sealing body that seals the opening of the outer can. The positive electrode of the electrode body and the sealing body are electrically connected by a positive electrode lead, and the negative electrode of the electrode body and the bottom of the outer can are electrically connected by a negative electrode lead.

[0003] Prior Art Literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2013-030494 Summary of the invention

[0006] If only one lead is connected to each of the positive and negative electrodes of the electrode body, the roundness of the electrode body can be improved, and the battery characteristics can be improved. However, in a cylindrical battery having only one lead for each of the positive and negative electrodes, reducing the internal resistance becomes a problem.

[0007] Therefore, an object of the present disclosure is to provide a cylindrical battery capable of reducing internal resistance in a current collecting structure in which each of the positive and negative electrodes has only one lead.

[0008] In order to solve the above-mentioned problems, the cylindrical battery involved in the present disclosure comprises: an electrode body, which is formed by winding a long positive electrode having a positive electrode core and a positive electrode composite layer and a long negative electrode having a negative electrode core and a negative electrode composite layer with a separator interposed therebetween; a bottomed cylindrical outer can that accommodates the electrode body; only one positive electrode lead, which is joined to the positive electrode and is led out from one of the two axial end portions of the electrode body; and only one negative electrode lead, which is joined to the negative electrode and is led out from the other of the two axial end portions of the electrode body, the positive electrode lead is joined between one end of the positive electrode composite layer on the winding start side and one end of the positive electrode composite layer on the winding end side in the longitudinal direction of the positive electrode, and when the position of the negative electrode composite layer facing the positive electrode start end is set as the first position and the center position of the portion facing the positive electrode lead is set as the second position in the longitudinal direction of the negative electrode, the negative electrode lead is joined between the first position and the second position, and the negative electrode core includes a contact portion that contacts the inner peripheral surface of the outer can.

[0009] According to the cylindrical battery according to the present disclosure, the internal resistance can be reduced in a current collecting structure in which each of the positive and negative electrodes has only one lead. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1This is a cross-sectional view in the axial direction of a cylindrical battery according to one embodiment of the present disclosure.

[0011] Figure 2 It is a perspective view of the electrode body of the cylindrical battery.

[0012] Figure 3 (a) is a top view of the inner surface of the positive electrode rolled out in a long strip. Figure 3 (b) is a top view of the outer surface of the positive electrode rolled out in a long strip. Figure 3 (c) is a top view of the inner surface of the negative electrode rolled out in a long strip. Figure 3 (d) is a top view of the outer surface of the negative electrode rolled out in a long strip.

[0013] Figure 4 This is a radial cross-sectional view including the negative electrode lead and a portion of the electrode body. DETAILED DESCRIPTION

[0014] Hereinafter, the embodiment of the cylindrical battery involved in the present disclosure will be described in detail with reference to the accompanying drawings. It was originally conceived to construct a new embodiment by appropriately combining the characteristic parts of the embodiments and modifications described below. In the following embodiments, the same symbols are given to the same structures in the drawings, and repeated descriptions are omitted. The multiple drawings are schematic diagrams, and the dimension ratios of the length, width, height, etc. of each component may not be consistent between different drawings. In this specification, the axial sealing body 17 side of the cylindrical battery 10 is set to "upper", and the axial bottom 68 side of the outer can 16 is set to "lower".

[0015] In the following Figure 3 In the top view of the electrodes (a) to (d) (negative electrode, positive electrode), the area indicated by the oblique lines is the composite layer formation area. In the following description, the technical idea of ​​the present disclosure is described by taking the case where the cylindrical battery is a lithium-ion secondary battery as an example, but the cylindrical battery of the present disclosure is not limited to a lithium-ion secondary battery, and may also be a cylindrical battery other than a lithium-ion secondary battery. In addition, among the structural elements described below, the structural elements that are not recorded in the independent claims representing the highest concept are arbitrary structural elements and are not required structural elements.

[0016] Figure 1 is a cross-sectional view in the axial direction of a cylindrical battery 10 according to one embodiment of the present disclosure. Figure 2 FIG. 1 is a perspective view of the electrode body 14 of the cylindrical battery 10. Figure 1As shown, a cylindrical battery (hereinafter referred to as a battery) 10 includes a wound electrode body 14, a non-aqueous electrolyte (not shown), a bottomed cylindrical metal outer can 16 that accommodates the electrode body 14 and the non-aqueous electrolyte, and a sealing body 17 that closes the opening of the outer can 16. Figure 2 As shown, the electrode body 14 has a wound structure in which a long positive electrode 11 and a long negative electrode 12 are wound with two long separators 13 interposed therebetween.

[0017] The negative electrode 12 is formed to be one size larger than the positive electrode 11 in order to prevent lithium precipitation. That is, the negative electrode 12 is formed to be longer than the positive electrode 11 in the long side direction and the width direction (short side direction). In addition, the two separators 13 are formed to be at least one size larger than the positive electrode 11, and are arranged to sandwich the positive electrode 11. The negative electrode 12 may also constitute the winding start end of the electrode body 14. However, generally, the separator 13 extends beyond the winding start side end of the negative electrode 12, and the winding start side end of the separator 13 becomes the winding start end of the electrode body 14.

[0018] The non-aqueous electrolyte includes a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. Among the non-aqueous solvents, for example, esters, ethers, nitriles, amides, and mixed solvents of two or more thereof may also be used. The non-aqueous solvent may also contain a halogen-substituted body in which at least a portion of the hydrogen atoms of these solvents are replaced with halogen atoms such as fluorine. In addition, the non-aqueous electrolyte is not limited to a liquid electrolyte, and may also be a solid electrolyte using a gel-like polymer or the like. For the electrolyte salt, a lithium salt such as LiPF6 is used.

[0019] The positive electrode 11 includes a positive electrode core 41 and positive electrode composite material layers 42 formed on both surfaces of the positive electrode core 41 (see Figure 3 (a), (b)). For the positive electrode core 41, a metal foil such as aluminum or aluminum alloy that is stable within the potential range of the positive electrode 11, a thin film that arranges the metal on the surface, etc. can be used. The positive electrode composite layer 42 includes a positive electrode active material, a conductive agent, and a binder. For example, a positive electrode composite slurry including a positive electrode active material, a conductive agent, and a binder can be applied to the positive electrode core 41, and the coating can be dried and then compressed to form a positive electrode composite layer 42 on both sides of the positive electrode core 41, thereby manufacturing the positive electrode 11.

[0020] The positive electrode active material is composed of a lithium-containing metal composite oxide as a main component. Examples of the metal elements contained in the lithium-containing metal composite oxide include Ni, Co, Mn, Al, B, Mg, Ti, V, Cr, Fe, Cu, Zn, Ga, Sr, Zr, Nb, In, Sn, Ta, and W. An example of a preferred lithium-containing metal composite oxide is a composite oxide containing at least one of Ni, Co, Mn, and Al.

[0021] As the conductive agent contained in the positive electrode composite material layer 42, carbon materials such as carbon black, acetylene black, Ketjen black, graphite, and carbon nanotubes can be exemplified. As the binder contained in the positive electrode composite material layer 42, fluororesins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyimide resin, acrylic resin, polyolefin resin, etc. can be exemplified. These resins can also be used in combination with cellulose derivatives such as carboxymethyl cellulose (CMC) or its salts, polyethylene oxide (PEO), etc.

[0022] The negative electrode 12 includes a negative electrode core 51 and negative electrode composite material layers 52 formed on both surfaces of the negative electrode core 51 (see Figure 3 (c), (d)). For the negative electrode core 51, a metal foil such as copper or copper alloy that is stable within the potential range of the negative electrode 12, a thin film that arranges the metal on the surface, etc. can be used. The negative electrode composite layer 52 contains a negative electrode active material and a binder. For example, a negative electrode composite slurry containing a negative electrode active material and a binder can be applied to the negative electrode core 51, and the coating can be dried and then compressed to form a negative electrode composite layer 52 on both sides of the negative electrode core 51, thereby manufacturing the negative electrode 12.

[0023] Generally, a carbon material that can reversibly absorb and release lithium ions is used for the negative electrode active material. Preferred carbon materials are graphites such as natural graphites such as flaky graphite, blocky graphite, and earthy graphite, blocky artificial graphite, and artificial graphites such as graphitized mesophase carbon microbeads. For the negative electrode composite layer 52, a Si material containing silicon (Si) may also be included as the negative electrode active material. In addition, metals alloyed with lithium other than Si, alloys containing the metals, compounds containing the metals, etc. may also be used in the negative electrode active material.

[0024] As for the binder contained in the negative electrode composite layer 52, fluororesin, PAN, polyimide resin, acrylic resin, polyolefin resin, etc. may be used as in the case of the positive electrode 11, but styrene-butadiene rubber (SBR) or a modified form thereof is preferably used. In addition to SBR, the negative electrode composite layer 52 may also contain CMC or a salt thereof, polyacrylic acid (PAA) or a salt thereof, polyvinyl alcohol, etc.

[0025] As the separator 13, a porous sheet having ion permeability and insulation is used. Specific examples of the porous sheet include microporous films, woven fabrics, nonwoven fabrics, etc. As the material of the separator 13, polyolefin resins such as polyethylene and polypropylene, cellulose, etc. are preferred. The separator 13 may be either a single-layer structure or a laminated structure. A heat-resistant layer may also be formed on the surface of the separator 13.

[0026] like Figure 1As shown in the figure, only one positive electrode lead 20 is joined to the positive electrode 11, and only one negative electrode lead 21 is joined to the negative electrode 12. Since only one positive and negative electrode lead 20 and 21 are joined to the electrode body 14, respectively, the roundness of the electrode body 14 is easily improved, and the battery characteristics such as battery life are easily improved. The battery 10 has an insulating plate 18 above the electrode body 14 and an insulating plate 19 below the electrode body 14. The positive electrode lead 20 is led out from one end (axial upper end) of the two axial ends of the electrode body 14, and extends to the sealing body 17 side through the through hole of the insulating plate 18. In addition, the negative electrode lead 21 is led out from the other end (axial lower end) of the two axial ends of the electrode body 14, and extends to the bottom 68 side of the outer can 16 through the through hole of the insulating plate 19. The positive electrode lead 20 is connected to the lower surface of the sealing plate 23 of the sealing body 17 by welding or the like. The terminal cover 27 constituting the top plate of the sealing body 17 is electrically connected to the sealing plate 23 and serves as a positive terminal. The negative electrode lead 21 is connected to the inner surface of the bottom 68 of the metal outer can 16 by welding or the like and serves as a negative terminal.

[0027] The positive electrode lead 20 is electrically connected to an intermediate portion of the positive electrode core 41, such as the center portion in the winding direction. Figure 1 As shown in FIG. 1 , the negative electrode lead 21 is electrically connected to the middle portion of the winding direction of the negative electrode core 51, and the negative electrode core 51 forms the outermost periphery of the electrode body 14, and the outermost negative electrode core 51 is made to abut against the inner peripheral surface of the outer can 16. The joining position of the positive electrode lead 20 in the positive electrode 11 and the joining position of the negative electrode lead 21 in the negative electrode 12, and the effects derived from these joining positions are described below using Figure 3 (a) to (d) are explained in detail.

[0028] The battery 10 further includes a resin gasket 28 disposed between the outer can 16 and the sealing body 17. The sealing body 17 is fixed to the opening of the outer can 16 by riveting via the gasket 28. Thus, the internal space of the battery 10 is sealed. The gasket 28 is sandwiched between the outer can 16 and the sealing body 17, and insulates the sealing body 17 from the outer can 16. The gasket 28 has the function of a sealing material for maintaining the airtightness of the interior of the battery, and the function of an insulating material for insulating the outer can 16 from the sealing body 17.

[0029] The outer can 16 accommodates the electrode body 14 and the non-aqueous electrolyte, and has a shoulder 38, a groove 34, a cylindrical portion 30, and a bottom 68. The groove 34 can be formed, for example, by spinning a portion of the side surface of the outer can 16 inwardly in the radial direction so as to be annularly recessed inwardly in the radial direction. When the sealing body 17 is fixed to the outer can 16 by riveting, the upper end of the outer can 16 is bent inwardly toward the peripheral edge 39 of the sealing body 17 to form the shoulder 38.

[0030] The sealing body 17 has a structure in which a sealing plate 23, a lower valve body 24, an insulating member 25, an upper valve body 26, and a terminal cover 27 are stacked in order from the electrode body 14 side. Each member constituting the sealing body 17 has, for example, a disc shape or a ring shape, and each member except the insulating member 25 is electrically connected to each other. The sealing plate 23 has at least one through hole 23a. In addition, the lower valve body 24 and the upper valve body 26 are connected at their respective central portions, and the insulating member 25 is interposed between their respective peripheral portions.

[0031] When the battery 10 generates abnormal heat and the internal pressure of the battery 10 increases, the lower valve body 24 deforms and breaks so as to push the upper valve body 26 toward the terminal cover 27, and the current path between the lower valve body 24 and the upper valve body 26 is cut off. When the internal pressure further increases, the upper valve body 26 breaks, and gas is discharged from the through hole 27a of the terminal cover 27. By discharging the gas, the internal pressure of the battery 10 can be prevented from excessively increasing and thus rupturing the battery 10, and the safety of the battery 10 can be improved.

[0032] Figure 3 (a) is a top view of the inner surface 11a of the positive electrode 11 rolled out in a long strip shape, Figure 3 (b) is a top view of the rolled outer surface 11b of the positive electrode 11 unfolded in a long strip. Figure 3 (c) is a top view of the inner surface 12a of the negative electrode 12 rolled out in a long strip shape. Figure 3 (d) is a plan view of the rolled outer surface 12 b of the negative electrode 12 that has been unrolled in a long strip shape.

[0033] In addition, Figure 3 In (a) and (b), the α direction indicates the long side direction of the positive electrode 11 developed in a strip shape, and the β direction indicates the width direction of the positive electrode 11 developed in a strip shape. Figure 3 In (c) and (d), the γ direction indicates the longitudinal direction of the negative electrode 12 developed in a strip shape, and the δ direction indicates the width direction of the negative electrode 12 developed in a strip shape.

[0034] like Figure 3 As shown in (a) and (b) of FIG. 1 , the positive electrode 11 includes a positive electrode core 41 and a positive electrode composite material layer 42 disposed on the positive electrode core 41 . Figure 3 As shown in (a) of FIG. 1 , the winding inner surface 11a of the positive electrode 11 has a first positive electrode core exposed portion 45 in the middle of the formation region of the positive electrode composite material layer 42 in the α direction. More specifically, the winding inner surface 11a of the positive electrode 11 has a first positive electrode core exposed portion 45 between one end 42a of the positive electrode composite material layer 42 on the winding start side and one end 42b of the positive electrode composite material layer 42 on the winding end side in the α direction. Figure 3As shown in (a) and (b) of FIG. 1 , the positive electrode 11 has a second positive electrode core exposed portion 46 on the winding outer surface 11 b at a position overlapping the first positive electrode core exposed portion 45 in the thickness direction.

[0035] The first positive electrode core exposed portion 45 is a portion where the positive electrode core 41 is exposed, and is provided at one end of the positive electrode 11 in the β direction (coinciding with the axial upper end). The positive electrode lead 20 is connected to the first positive electrode core exposed portion 45. If the first positive electrode core exposed portion 45 is provided between 40% and 60% of the length from the starting end to the end of the positive electrode 11 in the α direction with the starting end of the positive electrode 11 as a reference, the length of the positive electrode 11 can be effectively shortened. Figure 3 The current collecting path of the positive electrode 11 shown by arrows C and D in (a) can reduce the internal resistance of the battery 10, which is preferred. If the length of the first positive electrode core exposed portion 45 in the β direction is set to be less than 50% of the length of the positive electrode 11 in the β direction, the configuration area of ​​the positive electrode composite layer 42 can be increased, thereby increasing the capacity, which is preferred. In addition, the rigidity of the positive electrode 11 can be increased.

[0036] like Figure 3 As shown in (c) and (d) of FIG. 1 , the negative electrode 12 includes a negative electrode core 51 and a negative electrode composite material layer 52 disposed on the negative electrode core 51 . Figure 3 As shown in (d), in the γ direction, when the position of the negative electrode composite layer 52 facing the positive electrode starting end is set as the first position A and the center position of the portion facing the positive electrode lead 20 is set as the second position B, the negative electrode 12 has a first negative electrode core body exposed portion 55 located between the first position A and the second position B. The first negative electrode core body exposed portion 55 is provided at one end portion in the δ direction (coinciding with the axial lower end portion). The negative electrode lead 21 is connected to the first negative electrode core body exposed portion 55.

[0037] like Figure 1 As shown in FIG. 1 , the negative electrode core 51 has a contact portion 51a that contacts the inner circumference of the outer can 16, and the end of the winding end side of the negative electrode 12 in the γ direction is electrically connected to the outer can 16 constituting the negative terminal. Therefore, by joining the negative electrode lead 21 between the first position A and the second position B in the γ direction, it is joined to the inner circumference of the electrode body 14 relative to the positive electrode lead joining position, so that Figure 3 The distances of the three current collection paths indicated by arrows E, F, and G in (d) are close to equal distances. Therefore, carriers generated at any position in the γ direction of the negative electrode composite layer 52 are easily collected through a short current collection path. In this way, in the current collection structure in which the positive electrode 11 and the negative electrode 12 each have only one positive electrode lead 20 and one negative electrode lead 21, the internal resistance of the battery 10 can be reduced.

[0038] In addition, if the negative lead 21 is joined to a position greater than 35% and less than 95% of the length from the first position A to the second position B in the γ direction with the first position A as the reference, the current collection path of the negative electrode 11 can be effectively shortened. In addition, if the negative lead 21 is joined to a position greater than 50% and less than 80% of the length from the first position A to the second position B in the γ direction with the first position A as the reference, the path difference of the above three current collection paths can be reduced. Therefore, carriers generated at any position in the γ direction of the negative electrode composite layer 52 can be collected with a short current collection path, which can further reduce the internal resistance of the battery 10. If the δ direction length of the first negative electrode core exposed portion 55 is set to less than 50% of the δ direction length of the negative electrode 12, the configuration area of ​​the negative electrode composite layer 52 can be increased, and the capacity can be increased. In addition, the rigidity of the negative electrode 12 can be increased.

[0039] Figure 4 2 is a cross-sectional view in the radial direction including the negative electrode lead 21 and a portion of the electrode body 14. Figure 3 (a) and Figure 4 As shown in FIG. 1 , the positive electrode 11 has a third positive electrode core body exposed portion 47 for exposing the positive electrode core body 41 at a position opposite to the first negative electrode core body exposed portion 55. The third positive electrode core body exposed portion 47 is provided at a single end portion in the β direction (coinciding with the axial lower end portion). If the β direction length of the third positive electrode core body exposed portion 47 is set to be less than 50% of the β direction length of the positive electrode 11, the arrangement area of ​​the positive electrode composite agent layer 42 can be effectively increased, and the capacity can be increased. In addition, the rigidity of the positive electrode 11 can be increased.

[0040] like Figure 4 As shown, the negative electrode 12 has a second negative electrode core exposed portion 56 on the winding inner surface 12a at a position overlapping with the first negative electrode core exposed portion 55 in the thickness direction, and the positive electrode 11 has a fourth positive electrode core exposed portion 48 at a position opposite to the second negative electrode core exposed portion 56. If the β-direction length of the fourth positive electrode core exposed portion 48 is set to be less than 50% of the β-direction length of the positive electrode 11, the configuration area of ​​the positive electrode composite layer 42 can be effectively increased, and the capacity can be increased. In addition, the rigidity of the positive electrode 11 can be increased. Figure 3 As shown in (a) to (d) of FIG. 1 , in order to prevent short circuit, insulating tape 60 is affixed to the exposed core portions 45 , 46 , 47 , 48 of the positive electrode 11 , and insulating tape 70 is affixed to the exposed core portions 55 , 56 of the negative electrode 11 .

[0041] <Cylindrical battery of the embodiment>

[0042] In the long side direction of the negative electrode composite layer, when the position in the long side direction of the negative electrode opposite to the positive electrode starting end is set as the first position and the center position of the portion opposite to the positive electrode lead is set as the second position, only one negative electrode lead is joined at a position of 65% of the length from the first position to the second position based on the first position in the long side direction of the negative electrode, thereby manufacturing the cylindrical battery of the embodiment. In addition, the position of the negative electrode lead is determined based on the center of the negative electrode lead in the long side direction of the negative electrode.

[0043] <Cylindrical Battery of Comparative Example>

[0044] A cylindrical battery of the comparative example was prepared in the same manner as in the example except that a negative electrode core exposed portion was provided at the end on the winding start side instead of the middle portion in the longitudinal direction of the negative electrode and only one negative electrode lead was connected to the negative electrode core exposed portion.

[0045] [Evaluation of DC resistance]

[0046] Each cylindrical battery of the example and the comparative example was charged to a SOC (state of charge) of 50%, and then discharged at a constant current of 2450 mA (0.5 C) for 10 seconds. The DC resistance of the cylindrical battery was calculated based on the voltage drop during discharge.

[0047] [Test results]

[0048] [Table 1]

[0049]

[0050] In Table 1, the DC resistance of the cylindrical battery of the embodiment is expressed as a relative value when the DC resistance of the cylindrical battery of the comparative example is set to 100%. As shown in Table 1, the DC resistance of the cylindrical battery of the embodiment can be reduced by 5% relative to the DC resistance of the cylindrical battery of the comparative example. Therefore, according to the cylindrical battery of the present disclosure, the internal resistance of the battery can be reduced in a current collection structure in which the positive and negative electrodes each have only one lead.

[0051] In addition, the present disclosure is not limited to the above-mentioned embodiments and their variations, and various improvements and changes can be made within the scope of the matters described in the claims of the present application and their equivalents. For example, in the above-mentioned embodiments, the positive electrode lead 20 is connected to the winding inner surface 11a of the positive electrode 11, but the positive electrode lead can also be connected to the winding outer surface 11b of the positive electrode. In addition, the negative electrode lead 21 is connected to the winding outer surface 12b of the negative electrode 12, but the negative electrode lead can also be connected to the winding inner surface 12a of the negative electrode.

[0052] In addition, the case where the first and second positive electrode core exposed portions 45 and 46 are only provided at one end of the positive electrode 11 in the β direction is described. However, at least one of the positive electrode core exposed portion to which the positive electrode lead is joined and the positive electrode core exposed portion opposite to the negative electrode core exposed portion to which the negative electrode lead is joined may be provided in the entire area in the width direction of the positive electrode. In addition, the case where the first negative electrode core exposed portion 55 to which the negative electrode lead is joined is provided only at one end of the negative electrode 12 in the δ direction is described. However, the negative electrode core exposed portion to which the negative electrode lead is joined may also be provided in the entire area in the width direction of the negative electrode. In addition, the case where the sealing body 17 includes the positive terminal and the outer can 16 constitutes the negative terminal is described, but it may also be that the sealing body includes the negative terminal and the outer can constitutes the positive terminal.

[0053] Description of Reference Numerals

[0054] 10: Battery, 11: Positive electrode, 11a: Inner surface of winding, 11b: Outer surface of winding, 12: Negative electrode, 12a: Inner surface of winding, 12b: Outer surface of winding, 13: Separator, 14: Electrode body, 16: Outer can, 17: Sealing body, 18, 19: Insulating plate, 20: Positive electrode lead, 21: Negative electrode lead, 23: Sealing plate, 23a: Through hole, 24: Lower valve body, 25: Insulating member, 26: Upper valve body, 27: Terminal cover, 27a: Through hole, 28: Gasket, 30: Cylindrical portion, 34: Grooved portion, 38: Shoulder portion, 39: Peripheral portion , 41: positive electrode core, 42: positive electrode composite layer, 42a: one end of the positive electrode composite layer 42 on the winding starting side, 42b: one end of the positive electrode composite layer on the winding ending side, 45: first positive electrode core exposed portion, 46: second positive electrode core exposed portion, 47: third positive electrode core exposed portion, 48: fourth positive electrode core exposed portion, 51: negative electrode core, 51a: contact portion, 52: negative electrode composite layer, 55: first negative electrode core exposed portion, 56: second negative electrode core exposed portion, 60, 70: insulating tape, 68: bottom, A: first position, B: second position.

Claims

1. A cylindrical battery comprising: An electrode body, which is formed by winding a long positive electrode having a positive electrode core and a positive electrode composite layer and a long negative electrode having a negative electrode core and a negative electrode composite layer with a separator interposed therebetween; An outer container having a bottom and a cylindrical shape, which contains the electrode body; a single positive electrode lead connected to the positive electrode and extending from one of the two axial ends of the electrode body; and There is only one negative electrode lead, which is connected to the negative electrode and is led out from the other of the two axial ends of the electrode body. The positive electrode lead is joined between one end of the positive electrode composite material layer on the winding start side and one end of the positive electrode composite material layer on the winding end side in the longitudinal direction of the positive electrode. In the long side direction of the negative electrode, when the position of the negative electrode composite layer facing the positive electrode starting end is set as a first position, and the center position of the portion facing the positive electrode lead is set as a second position, the negative electrode lead is joined between the first position and the second position, The negative electrode core includes a contact portion that contacts the inner peripheral surface of the outer can.

2. The cylindrical battery according to claim 1, wherein: The positive electrode lead is joined to a position that is 40% or more and 60% or less of the length from the starting end to the end of the positive electrode, with the starting end of the positive electrode as a reference, in the longitudinal direction of the positive electrode. The negative electrode lead is joined at a position that is 35% or more and 95% or less of the length from the first position to the second position with reference to the first position in the longitudinal direction of the negative electrode.

3. The cylindrical battery according to claim 2, wherein: The negative electrode lead is joined at a position that is 50% or more and 80% or less of the length from the first position to the second position with reference to the first position in the longitudinal direction of the negative electrode.

4. The cylindrical battery according to any one of claims 1 to 3, wherein The positive electrode core body exposed portion where the positive electrode core body is exposed is provided at a position where two surfaces of one end portion in the width direction of the positive electrode overlap each other, and the positive electrode lead is connected to one side of the positive electrode core body exposed portion. The length of the positive electrode substrate exposed portion in the width direction of the positive electrode is 50% or less of the length of the positive electrode in the width direction.

5. The cylindrical battery according to any one of claims 1 to 3, wherein The negative electrode core body exposed portion where the negative electrode core body is exposed is disposed at a position where both surfaces of one end portion in the width direction of the negative electrode overlap each other, and the negative electrode lead is joined to one side of the negative electrode current collector exposed portion. The length of the negative electrode substrate exposed portion in the width direction of the negative electrode is 50% or less of the length of the negative electrode in the width direction.

6. The cylindrical battery according to any one of claims 1 to 3, wherein The negative electrode core body exposed portion where the negative electrode core body is exposed is provided on both sides of the negative electrode, and the negative electrode lead is connected to one of the negative electrode current collector exposed portions. A positive electrode core exposed portion for exposing the positive electrode core is provided at a position of the positive electrode facing the negative electrode current collector exposed portion.

7. The cylindrical battery according to claim 5, wherein: A positive electrode core body exposed portion is provided at a position of the positive electrode facing the negative electrode current collector exposed portion to expose the positive electrode core body; The length of the positive electrode substrate exposed portion in the width direction of the positive electrode is 50% or less of the length of the positive electrode in the width direction.

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