Cylindrical battery

Abstract

A cylindrical battery (10) is provided with: an electrode body (14) in which a positive electrode (11) and a negative electrode (12) are wound with a separator (13) therebetween; an outer can (20) in which the electrode body (14) is housed; a sealing body (19) that is placed on a slotted portion (28) formed along the circumferential direction of the outer can (20) with a gasket (24) therebetween; and an upper insulating plate (30) disposed between the slotted portion (28) and the electrode body (14), the upper insulating plate (30) having a main body (31) placed on the electrode body (14) and a folded portion (32) formed by folding the outer peripheral portion toward the main body (31) side, and the upper insulating plate (30) being biased toward the electrode body (14) side via the folded portion (32).

Description

Technical Field

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

[0002] The cylindrical battery comprises an electrode body formed by winding a positive electrode and a negative electrode with a separator interposed therebetween; an outer can housing the electrode body; a sealing body sealing the opening of the outer can; and an upper insulating plate disposed between a groove formed along the circumference of the outer can and the electrode body.

[0003] The upper insulating plate electrically insulates the electrode assembly from the sealing member. Furthermore, if a cylindrical battery malfunctions and gas is released, the upper insulating plate prevents the released gas from contacting the slots of the outer can. If the cylindrical battery malfunctions and gas is released to the outside of the battery via the upper insulating plate, the released gas could strike the slots, creating holes there. High-temperature gas could then be ejected from these holes toward the sides of the outer can, potentially spreading to adjacent cylindrical batteries.

[0004] For example, Patent Document 1 discloses an upper insulating plate having a peripheral thickness that is 130% to 300% of the central thickness. The upper insulating plate of Patent Document 1 is less likely to fall out of the groove of the outer can due to abnormal gas discharge.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2013-131430 Summary of the Invention

[0008] However, if the gas discharge speed during an abnormality increases, even the upper insulating plate of Patent Document 1 may not be retained in the groove portion of the outer can and may be released to the outside of the battery.

[0009] Therefore, an object of the present disclosure is to provide a cylindrical battery in which, when gas is released in an abnormal situation, an insulating plate disposed between a groove portion of an outer can and an electrode body is unlikely to be released to the outside of the battery.

[0010] The cylindrical battery disclosed herein comprises: an electrode body formed by winding a positive electrode and a negative electrode with a separator interposed therebetween; an outer can that houses the electrode body; a sealing body that is placed on a groove portion formed along the circumference of the outer can with a gasket interposed therebetween; and an insulating plate that is arranged between the groove portion and the electrode body. The cylindrical battery is characterized in that the insulating plate has a main body placed on the electrode body and a folded portion formed by folding the outer peripheral portion toward the main body side, and the insulating plate is applied toward the electrode body side by means of the folded portion.

[0011] According to the cylindrical battery disclosed herein, it is possible to realize a cylindrical battery in which the insulating plate is unlikely to be released to the outside of the battery when gas is discharged in an abnormal situation. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is an axial cross-sectional view showing a cylindrical battery as an example of an embodiment.

[0013] Figure 2 It is a perspective view showing an upper insulating plate as an example of an embodiment.

[0014] Figure 3 is a top view showing the upper insulating plate unfolded.

[0015] Figure 4 It is a perspective view showing an upper insulating plate as another example of the embodiment.

[0016] Figure 5 is a top view showing the upper insulating plate unfolded.

[0017] Figure 6 It is a perspective view showing an upper insulating plate as another example of the embodiment.

[0018] Figure 7 is a top view showing the upper insulating plate unfolded.

[0019] Figure 8 It is a perspective view showing an upper insulating plate as another example of the embodiment.

[0020] Figure 9 is a top view showing the upper insulating plate unfolded. DETAILED DESCRIPTION

[0021] In the following description, specific shapes, materials, directions, numerical values, etc. are illustrative for facilitating understanding of the present disclosure and may be modified as appropriate depending on the application, purpose, specifications, etc.

[0022] [Cylindrical battery]

[0023] use Figure 1 A cylindrical battery 10 as an example of an embodiment will be described.

[0024] The cylindrical battery 10 is a non-aqueous electrolyte secondary battery (lithium-ion battery) using a non-aqueous electrolyte. However, the cylindrical battery disclosed herein is not limited to the non-aqueous electrolyte secondary battery of this embodiment; it may be a primary battery or a battery using an aqueous electrolyte. Below, the various components are sometimes described using the axial, radial, and circumferential directions of the cylindrical battery 10. Furthermore, the cylindrical battery 10 may be described with the sealing body 19 side in the axial direction (height direction) being the "top" and the bottom 20A side of the outer can 20 being the "bottom."

[0025] like Figure 1 As shown, the cylindrical battery 10 includes an electrode body 14, a nonaqueous electrolyte, a bottomed cylindrical outer can 20 that houses the electrode body 14 and the electrolyte, and a sealing member 19 that seals the opening of the outer can 20. The electrode body 14 includes a positive electrode 11, a negative electrode 12, and a separator 13 sandwiched between the positive electrode 11 and the negative electrode 12, and has a wound structure in which the positive electrode 11 and the negative electrode 12 are wound with the separator 13 interposed therebetween. The outer can 20 is a bottomed cylindrical container having a bottom 20A and a cylindrical portion 20B.

[0026] The cylindrical battery 10 includes an upper insulating plate 30, which is positioned between the groove 28 formed along the circumference of the outer can 20 and the electrode body 14. Details will be described later. The upper insulating plate 30 has a main body 31 that rests on the electrode body 14 and a folded portion 32 formed by folding the outer periphery toward the main body 31. The folded portion 32 biases the upper insulating plate 30 toward the electrode body 14. This prevents the upper insulating plate 30 from falling off during gas discharge during an abnormal situation.

[0027] The non-aqueous electrolyte comprises, for example, a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. The non-aqueous solvent may be an ester, ether, nitriles, amides, or a mixture of two or more thereof. The non-aqueous solvent may contain a solvent in which at least a portion of the hydrogen atoms in the solvent is replaced with a halogen atom such as fluorine. It should be noted that the non-aqueous electrolyte is not limited to a liquid electrolyte and may also be a solid electrolyte using a gel-like polymer. The electrolyte salt may be a lithium salt such as LiPF6.

[0028] The electrode body 14 includes an elongated positive electrode 11, an elongated negative electrode 12, and two elongated separators 13. Furthermore, the electrode body 14 includes a positive electrode lead 17 connected to the positive electrode 11 and a negative electrode lead 18 connected to the negative electrode 12 as electrode leads. In order to suppress lithium precipitation, the negative electrode 12 is formed to be slightly larger than the positive electrode 11. Therefore, the lower end of the negative electrode 12 is positioned closer to the bottom 20A of the outer can 20 than the lower end of the positive electrode 11. The two separators 13 are formed to be at least slightly larger than the positive electrode 11, and are, for example, arranged so as to sandwich the positive electrode 11.

[0029] The positive electrode 11 comprises a positive electrode core and positive electrode mixture layers disposed on both surfaces of the positive electrode core. The positive electrode core can be made of a metal foil, such as aluminum or an aluminum alloy, that is stable within the potential range of the positive electrode 11, or a film having such a metal disposed on its surface. The positive electrode mixture layers contain a positive electrode active material, a conductive agent such as acetylene black, and a binder such as polyvinylidene fluoride (PVdF). The positive electrode 11 can be fabricated by coating the positive electrode core with a positive electrode mixture slurry containing the positive electrode active material, conductive agent, and binder, drying the coating, and then compressing the coating to form the positive electrode mixture layers on both surfaces of the positive electrode core.

[0030] For example, a lithium transition metal composite oxide is used as the positive electrode active material. Examples of the metal elements contained in the lithium transition 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 transition metal composite oxide is a lithium metal composite oxide containing at least one of Ni, Co, and Mn. Specific examples include composite oxides containing Ni, Co, and Mn and composite oxides containing Ni, Co, and Al.

[0031] The negative electrode 12 comprises a negative electrode core and negative electrode mixture layers disposed on both surfaces of the negative electrode core. The negative electrode core can be made of a metal foil, such as copper or a copper alloy, that is stable within the potential range of the negative electrode 12, or a film having such a metal disposed on its surface. The negative electrode mixture layers contain a negative electrode active material and a binder, such as styrene butadiene rubber (SBR). The negative electrode 12 can be fabricated by coating the negative electrode core with a negative electrode mixture slurry containing the negative electrode active material, a binder, and the like, drying the coating, and then compressing the coating to form the negative electrode mixture layers on both surfaces of the negative electrode core.

[0032] For the negative electrode active material, for example, natural graphite such as flaky graphite, block graphite, and earthy graphite, block artificial graphite, and artificial graphite such as graphitized mesophase carbon microbeads can be used. Metals alloyed with lithium, such as Si and Sn, alloys containing such metals, and compounds containing such metals can be used as the negative electrode active material, and these can also be used in combination with graphite. A preferred example of such an active material is a SiO2 phase or a silicate phase such as lithium silicate, or a Si-containing material in which Si particles are dispersed in an amorphous carbon phase.

[0033] An upper insulating plate 30 and a lower insulating plate 16, which will be described in detail later, are respectively arranged above and below the electrode body 14. Figure 1In the illustrated example, positive electrode lead 17 attached to positive electrode 11 extends through opening 31B of upper insulating plate 30 toward sealing member 19, while negative electrode lead 18 attached to negative electrode 12 extends through the outside of lower insulating plate 16 toward bottom 20A of outer can 20. Positive electrode lead 17 is connected by welding or the like to the inner surface of valve portion 19A of sealing member 19, which faces the inside of outer can 20. Sealing member 19 serves as the positive electrode terminal. Negative electrode lead 18 is connected by welding or the like to the inner surface of bottom 20A of outer can 20. Outer can 20 serves as the negative electrode terminal.

[0034] A gasket 24 is provided between the outer can 20 and the sealing body 19 to ensure the airtightness of the interior of the battery and the insulation between the outer can 20 and the sealing body 19. The cylindrical portion 20B includes an annular groove portion 28 and an annular shoulder portion 29 along the circumferential direction. The groove portion 28 is formed by spinning a portion of the cylindrical portion 20B so that it is recessed radially inward. The shoulder portion 29 is formed when the upper end portion of the cylindrical portion 20B is bent radially inward and riveted to the peripheral portion of the sealing body 19, and extends radially inward. The sealing body 19 is fixed to the outer can 20 by this riveting in a manner such that it is clamped by the shoulder portion 29 and the groove portion 28 via the gasket 24.

[0035] The sealing body 19 is a disc-shaped member equipped with a gas exhaust valve. The sealing body 19 includes a valve portion 19A that ruptures when the internal pressure of the battery exceeds a predetermined threshold. The valve portion 19A includes a lower convex portion protruding toward the inside of the battery and disposed in the radial center, and a thin-walled portion formed around the lower convex portion. The thickness of the thin-walled portion decreases as it moves radially outward. When the internal pressure of the cylindrical battery 10 rises due to an abnormality, the annular end of the thin-walled portion ruptures, forming a gas exhaust port.

[0036] [Upper insulation board]

[0037] use Figures 1 to 3 , the upper insulating plate 30 as an example of an embodiment will be described.

[0038] like Figure 1 As shown, the upper insulating plate 30 is disposed between the groove 28 formed along the circumference of the outer can 20 and the electrode body 14. The upper insulating plate 30 electrically insulates the electrode body 14 from the sealing member 19. Furthermore, if the cylindrical battery 10 discharges gas due to an abnormality, the upper insulating plate 30 prevents the discharged gas from contacting the groove 28 of the outer can 20.

[0039] The upper insulating plate 30 has a main body 31 placed on the electrode body 14 and a folded portion 32 formed by folding the outer periphery toward the main body 31. Here, folded means that the angle formed by the main body 31 and the folded portion 32 is approximately 60° or less. The upper insulating plate 30 is folded after being inserted into the outer can 20, as described in detail later.

[0040] The upper insulating plate 30 is biased toward the electrode body 14 from the groove 28 by the folded portion 32. More specifically, inside the outer can 20, the folded portion 32 is engaged with the lower portion of the groove 28. The force of the folded portion 32 biases the upper insulating plate 30 toward the electrode body 14. Consequently, a downward force acts on the upper insulating plate 30.

[0041] Because the upper insulating plate 30 in this embodiment exerts a downward force, it prevents gas from being released to the outside of the battery when the cylindrical battery 10 experiences an abnormality. This prevents the released gas from striking the groove 28 of the outer can 20 and forming a hole therein.

[0042] Furthermore, according to the upper insulating plate 30 , variations in the gap between the groove 28 of the outer can 20 and the electrode body 14 can be absorbed by the size of the angle between the main body 31 and the folded portion 32 .

[0043] The upper insulating plate 30 preferably has a thickness of 0.2 mm to 0.7 mm. Furthermore, the upper insulating plate 30 is made of an elastic material, preferably a thermoplastic resin. Polypropylene or the like is preferably used for the upper insulating plate 30.

[0044] like Figure 2 and Figure 3 As shown, the upper insulating plate 30 has a generally disc-shaped main body 31 and four generally trapezoidal folds 32 formed on the outer periphery of the main body 31. The folds 32 are easily formed by folding the outer periphery of the upper insulating plate 30 at mutually separated locations on the outer periphery of the main body 31. Straight lines are formed on a portion of the outer periphery of the main body 31, and these straight lines are arranged at equal intervals (for example, every 90° relative to the center of the main body 31). This allows the upper insulating plate 30 to be uniformly loaded by the folds 32, and the outer periphery of the main body 31 can be made approximately circular. The main body 31 has a hole 31A formed approximately in the center and an opening 31B formed on one side. During manufacturing, electrolyte is injected through hole 31A, and gas is discharged from hole 31A in the event of an abnormality. The positive electrode lead 17 attached to the positive electrode 11 passes through opening 31B and extends toward the sealing body 19.

[0045] The radial length of the folded portion 32 is preferably longer than the radial length of the groove portion 28. Thus, the insulation performance of the electrode body 14 and the sealing body 19 can be improved. A linear groove portion 33 is formed at the boundary between the main body 31 and the folded portion 32. The groove portion 33 is arranged in a linear portion in the outer periphery of the main body 31. The folded portion 32 is folded toward the main body 31 side along the groove portion 33. Thus, the folded portion 32 is easily folded during manufacturing. The cross-sectional shape of the groove portion 33 can be V-shaped or concave.

[0046] In addition, if Figure 3 As shown, the upper insulating plate 30 has protrusions that protrude radially outward from the main body 31 when the folded portion 32 is unfolded. The protrusions corresponding to the folded portion 32 are arranged on the outer periphery of the main body 31 so as to be separated from each other.

[0047] During the manufacturing process of the cylindrical battery 10, after the electrode body 14 is housed inside the outer can 20, the upper insulating plate 30 is placed above the electrode body 14. When the upper insulating plate 30 is inserted into the outer can 20, the folded portion 32 of the upper insulating plate 30 is bent upward approximately 90 degrees along the groove 33.

[0048] Next, a portion of the cylindrical portion 20B of the outer can 20 (above the upper insulating plate 30) is spun radially inward, thereby forming the groove 28. During the formation of the groove 28, the folded portion 32 bends toward the main body 31, locking the folded portion 32 in the groove 28. Furthermore, as the folded portion 32 bends toward the main body 31, a radially inward force acts on the upper insulating plate 30. This allows the main body 31 to bend downward.

[0049] [Other embodiments]

[0050] use Figures 4 to 9 , the upper insulating plates 40, 50, and 60 as another example of the embodiment will be described. Hereinafter, only the structures different from the upper insulating plate 30 described above will be described, and the description of the same structures as the upper insulating plate 30 will be omitted.

[0051] like Figure 4 and Figure 5 As shown, the upper insulating plate 40 has a generally disc-shaped main body 41 and eight generally trapezoidal folds 42 formed on the outer periphery of the main body 41. The outer periphery of the main body 41 is formed in a regular octagonal shape, and the folds 42 are formed continuously. The main body 41 has a hole 41A and an opening 41B. Grooves 43 are formed on the outer periphery of the main body 41, forming the boundaries between the main body 41 and the folds 42.

[0052] like Figure 6 and Figure 7 As shown, the upper insulating plate 50 has a generally disc-shaped main body 51 and multiple (four in this embodiment) folded portions 52 formed on the outer periphery of the main body 51. Straight portions are formed on a portion of the outer periphery of the main body 51 at predetermined angles (90° in this embodiment) relative to the center of the main body 51, and the folded portions 52 are formed along these straight portions. The main body 51 has a hole 51A and an opening 51B. When unfolded, the inner and outer peripheries of the folded portions 52 are arcuate. A groove 53 is formed in the straight portion that forms the boundary between the main body 51 and the folded portion 52.

[0053] like Figure 8 and Figure 9 As shown, the upper insulating plate 60 has a generally disc-shaped main body 61 and multiple (in this embodiment, four) generally arc-shaped folded portions 62 formed on the outer periphery of the main body 61. Straight portions are formed on a portion of the outer periphery of the main body 61 at predetermined angles (in this embodiment, every 90 degrees) relative to the center of the main body 61, and the folded portions 62 are formed along these straight portions. The main body 61 has a hole 61A and an opening 61B. When unfolded, the folded portions 62 have an arc-shaped inner periphery and a straight outer periphery. A groove 63 is formed in the straight portion that forms the boundary between the main body 61 and the folded portion 62.

[0054] It should be noted that the present disclosure is not limited to the above-described embodiment and its modified examples, and various changes and improvements can be made within the scope of the matters described in the technical claims of the present application.

[0055] In addition, the present disclosure is further described through the following embodiments.

[0056] Structure 1: A cylindrical battery comprising: an electrode body formed by winding a positive electrode and a negative electrode with a separator interposed therebetween; an outer can that houses the electrode body; a sealing body that is placed on a groove portion along the circumference of the outer can with a gasket interposed therebetween; and an insulating plate that is arranged between the groove portion and the electrode body, wherein the insulating plate has a main body placed on the electrode body and a folded portion formed by folding the outer periphery of the insulating plate toward the main body, and is biased from the groove portion toward the electrode body by means of the folded portion.

[0057] Structure 2: The cylindrical battery according to Structure 1, wherein the insulating plate is curved so as to bulge toward the electrode body.

[0058] Structure 3: The cylindrical battery according to Structure 1 or 2, wherein the folded portion is formed by folding the outer peripheral portion along a groove portion formed in the insulating plate.

[0059] Structure 4: The cylindrical battery according to any one of Structures 1 to 3, wherein a plurality of the folded portions are formed on the outer circumference of the body.

[0060] Description of reference numerals:

[0061] 10 Cylindrical battery, 11 Positive electrode, 12 Negative electrode, 13 Separator, 14 Electrode body, 16 Lower insulating plate, 17 Positive electrode lead, 18 Negative electrode lead, 19 Sealing member, 19A Valve, 20 Outer can, 20A Bottom, 20B Cylindrical portion, 24 Gasket, 28 Grooved portion, 29 Shoulder, 30 Upper insulating plate, 31 Main body, 31A Hole, 31B Opening, 32 Folded portion, 33 Groove, 40 Upper insulating plate, 41 Main body, 41A Hole, 41B Opening, 42 Folded portion, 43 Groove, 50 Upper insulating plate, 51 Main body, 51A Hole, 51B Opening, 52 Folded portion, 53 Groove, 60 Upper insulating plate, 61 Main body, 61A Hole portion, 61B opening portion, 62 folded portion, 63 groove portion.

Claims

1. A cylindrical battery comprising: an electrode body formed by winding a positive electrode and a negative electrode with a separator interposed therebetween; an outer can housing the electrode body; a sealing member placed with a gasket interposed therebetween in a groove formed along the circumference of the outer can; and an insulating plate disposed between the groove and the electrode body, wherein: The insulating plate includes: a main body placed on the electrode body; and a folded portion formed by folding the outer peripheral portion of the insulating plate toward the main body. The insulating plate is urged toward the electrode body by the folded portion.

2. The cylindrical battery according to claim 1, wherein The insulating plate is curved so as to bulge toward the electrode body.

3. The cylindrical battery according to claim 1 or 2, wherein The folded portion is formed by folding the outer peripheral portion along a groove portion formed in the insulating plate.

4. The cylindrical battery according to claim 1 or 2, wherein A plurality of folding portions are formed on the outer circumference of the main body.

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