Cylindrical battery
Reinforcing the inner can of cylindrical batteries with insulating resin on its bent and flange portions addresses deformation and sealing issues, enhancing performance and quality by preventing short circuits and leaks.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- FDK CORP
- Filing Date
- 2022-06-01
- Publication Date
- 2026-05-26
Smart Images
Figure 0007865790000002 
Figure 0007865790000003 
Figure 0007865790000004
Abstract
Description
Technical Field
[0001] The present invention relates to a cylindrical battery.
Background Art
[0002] As cylindrical batteries, various forms are known. For example, a conductive inner can containing a spiral electrode body formed by winding a pair of strip-shaped electrode plates through a separator is fitted into an outer can, and a sealing lid is caulked and attached to the bent edge of the outer can through an insulating packing placed on the flange edge formed at the upper end opening of the conductive inner can. There is known a cylindrical battery in which the flange edge of the conductive inner can is coated with an insulating resin layer (Patent Document 1).
[0003] Also known is a battery comprising a cylindrical unipolar current collecting inner can that houses a power generation element and has a protrusion formed on its outer upper surface, a unipolar terminal兼用 outer can into which the inner can is fitted and the protrusion is in contact with the inner surface and electrically connected, and an insulating packing supported on the flange portion of the inner can to insulate the outer can from the other-polarity terminal兼用 sealing lid, and in which a peripheral rising wall of an insulating plate disposed on the inner bottom surface of the outer can is interposed in the gap between the outer can and the inner can (Patent Document 2).
[0004] Also known is a spiral electrode type battery comprising a bottomed cylindrical metal inner can having a sealing seat surface with an upper peripheral edge bent inward, a bottomed cylindrical metal outer can that houses this, a dish-shaped metal terminal plate that closes the opening of this outer can, and an annular sealing gasket that is attached to the periphery of this terminal plate and is compressed by caulking the opening edge of the outer can inward, and in which a power generation element formed by alternately stacking a strip-shaped positive electrode, separator, and negative electrode and spirally winding them is loaded into the inner can via insulating plates on its upper and lower surfaces (Patent Document 3).
Prior Art Documents
Patent Documents
[0005]
Patent Document 1
Patent Document 2
[0006] By the way, in a cylindrical battery comprising a bottomed outer can having an opening sealed by a sealing plate, and an inner can housed inside it, where the outer edge of the sealing plate and a gasket covering it are fixed by crimping the opening edge of the outer can toward the inner can, supported by a bent portion provided on the inner can and a flange portion extending through it, the following may occur.
[0007] In other words, the pressing force applied when crimping the opening edge of the outer can to the inner can side via the sealing plate and gasket can cause the bent portion and flange portion of the inner can to bend and deform toward the bottom of the outer can. Here, the inner can of a cylindrical battery houses a power generation element including positive and negative electrode layers provided via a separator, and one of the electrode layers with either positive or negative polarity is electrically connected to the inner can and the outer can. If the bent portion and flange portion of the inner can, which is designated as one of the polarities, deform toward the bottom due to the pressing force applied when crimping the outer can, as described above, and come into contact with the electrode layer of the power generation element with the other polarity, a short circuit failure will occur. Furthermore, if the gasket is deformed irregularly due to the deformation of the bent portion and flange portion of the inner can caused by the pressing force applied when crimping the outer can, the sealing of the cylindrical battery cannot be adequately maintained.
[0008] Thus, deformation of the inner casing can lead to a decrease in the performance and quality of cylindrical batteries. In one aspect, the present invention aims to realize a cylindrical battery in which deformation of the inner casing is suppressed. [Means for solving the problem]
[0009] In one embodiment, the device includes a sealing plate, a gasket covering the outer edge of the sealing plate, a bottomed outer can having an opening sealed by the sealing plate, and an inner can housed inside the outer can, having a side wall portion extending along the inner wall surface of the outer can, and a flange portion extending inward from the end of the side wall portion on the opening side via a bent portion, wherein the opening edge of the opening of the outer can is crimped to the side of the bent portion and flange of the inner can via the outer edge of the sealing plate and the gasket, and the inner can has the bent portion and flange on the side opposite to the side of the outer edge of the sealing plate and the gasket. Fixed to the inner surface A cylindrical battery having an insulating resin is provided. [Effects of the Invention]
[0010] One aspect of this approach is that it becomes possible to create a cylindrical battery with reduced deformation of the inner casing. [Brief explanation of the drawing]
[0011] [Figure 1] This is a diagram illustrating an example of a cylindrical battery. [Figure 2] This is a diagram illustrating an example of a manufacturing method for cylindrical batteries. [Figure 3] This diagram illustrates the thickness of the insulating resin provided in the inner container. [Modes for carrying out the invention]
[0012] Figure 1 illustrates an example of a cylindrical battery. Figure 1 schematically shows a cross-sectional view of the main parts of an example of a cylindrical battery. The cylindrical battery 1 shown in Figure 1 is an example of a lithium primary battery. The cylindrical battery 1 includes a sealing plate 10, a gasket 20, an outer casing 30, an inner casing 40, an insulating plate 50, and a power generation element 60.
[0013] The sealing plate 10 is a metal disc made of stainless steel or the like. The sealing plate 10 is electrically conductive. The sealing plate 10 is, for example, a dish-shaped or hat-shaped plate with a flange on its outer edge 11. The sealing plate 10 is electrically connected to one of the electrode layers of the positive and negative electrode layers contained in the power generation element 60 of the cylindrical battery 1, and functions as the electrode (electrode terminal) of that polarity of the cylindrical battery 1. In this example, the sealing plate 10 is electrically connected to the negative electrode layer 62 of the power generation element 60, and functions as the negative electrode (negative electrode terminal) of the cylindrical battery 1.
[0014] A gasket 20 is provided on the outer edge 11 of the sealing plate 10. The outer edge 11 of the sealing plate 10 is covered with the gasket 20. That is, the outer edge 11 of the sealing plate 10 is covered with the gasket 20 from one side to the opposite side. Various insulating materials with insulating properties are used for the gasket 20. For example, insulating resin materials such as polypropylene resin and fluororesin are used for the gasket 20.
[0015] The outer casing 30 is a bottomed cylindrical can made of metal such as stainless steel. The outer casing 30 is conductive. The outer casing 30 has a bottom 32, a side wall 31 rising from the edge of the bottom 32, and an opening 33 located opposite the bottom 32. The opening 33 at one end of the bottomed outer casing 30 is sealed by a sealing plate 10 whose outer edge 11 is covered with a gasket 20. The outer casing 30 is electrically connected to the electrode layer of the opposite polarity to the electrode layer electrically connected to the sealing plate 10 among the positive and negative electrode layers contained in the power generation element 60 of the cylindrical battery 1, and functions as the electrode (electrode terminal) of that polarity of the cylindrical battery 1. In this example, the outer casing 30 is electrically connected to the positive electrode layer 61 of the power generation element 60 and functions as the positive electrode (positive electrode terminal) of the cylindrical battery 1.
[0016] The inner can 40 is a cylindrical can made of metal such as stainless steel. The inner can 40 has conductivity. The inner can 40 is accommodated inside the outer can 30. The inner can 40 has a side wall portion 41 extending along the inner wall surface 31a of the side wall portion 31 of the outer can 30, a bent portion 42 bent inward from the end of the side wall portion 41 on the opening 33 side of the outer can 30, and a flange portion 43 extending inward from the side wall portion 41 through the bent portion 42. It can also be said that the base portion of the flange portion 43 of the inner can 40 is the bent portion 42. The inner surface of the bent portion 42 may be a surface (R surface) curved in an arc shape in cross section. The bent portion 42 can also be referred to as the R portion of the inner can 40.
[0017] The inner can 40 is accommodated inside the outer can 30 such that its side wall portion 41 contacts the inner wall surface 31a of the side wall portion 31 of the outer can 30. For example, the inner can 40 is fitted (or attached) inside the inner wall surface 31a of the outer can 30 and is accommodated inside the outer can 30. The inner can 40 contacts the outer can 30 and is electrically connected to the outer can 30.
[0018] The inner can 40 is electrically connected to the electrode layer of the opposite polarity to the electrode layer electrically connected to the sealing plate 10 among the positive and negative electrode layers included in the power generation element 60 of the cylindrical battery 1, and is also electrically connected to the outer can 30. In this example, the inner can 40 is electrically connected to the positive electrode layer 61 of the power generation element 60 and is also electrically connected to the outer can 30. For example, the inner can 40 is electrically connected to the positive electrode layer 61 by being provided such that the positive electrode layer 61 of the power generation element 60 contacts the inner wall surface 41a of the side wall portion 41, and is electrically connected to the outer can 30 by being provided such that the side wall portion 41 contacts the inner wall surface 31a of the side wall portion 31 of the outer can 30. The outer can 30 is electrically connected to the positive electrode layer 61 of the power generation element 60 through the inner can 40.
[0019] The insulating plate 50 is provided on the bottom 32 inside the outer can 30. Various insulating materials having insulating properties are used for the insulating plate 50. The power generation element 60 has a positive electrode layer 61, a negative electrode layer 62, and a separator 63 interposed between the positive electrode layer 61 and the negative electrode layer 62. In the power generation element 60, a sheet-like positive electrode layer 61 and a negative electrode layer 62 are wound through a sheet-like separator 63 to form a cylindrical electrode body. For example, when the cylindrical battery 1 is a primary lithium battery, the positive electrode layer 61 uses a metal foil such as stainless steel with a positive electrode mixture containing manganese dioxide as a positive electrode active material provided on both sides. A lithium metal foil as a negative electrode active material is used for the negative electrode layer 62. The lithium metal foil of the negative electrode layer 62 is electrically connected to the negative electrode current collecting pin 64 through a negative electrode current collector. An insulating material such as a microporous film or a non-woven fabric is used for the separator 63. The sheet-like positive electrode layer 61 and the sheet-like negative electrode layer 62 electrically connected to the negative electrode current collecting pin 64 are wound in a state of being laminated through the sheet-like separator 63 to realize the power generation element 60 which is a cylindrical electrode body.
[0020] The power generation element 60 is housed inside the inner can 40 provided on the bottom portion 32 of the outer can 30 with the insulating plate 50, that is, inside the side wall portion 41, the bent portion 42, and the flange portion 43 of the inner can 40. The insulating plate 50 suppresses direct contact between the positive electrode layer 61, the negative electrode layer 62, and the negative electrode current collecting pin 64 exposed at the lower portion of the power generation element 60 and the bottom portion 32 of the outer can 30.
[0021] In this example, the power generation element 60 is wound such that the positive electrode layer 61 becomes the outermost layer, and the outermost positive electrode layer 61 is provided so as to contact the inner wall surface 41a of the side wall portion 41 of the inner can 40. Thereby, the positive electrode layer 61 of the power generation element 60 is electrically connected to the inner can 40 and electrically connected to the outer can 30 through the inner can 40. The power generation element 60 is housed inside the inner can 40 such that the positive electrode layer 61, the negative electrode layer 62, and the separator 63 (the upper ends in their housed states) at the outer peripheral portion thereof face the bent portion 42 and the flange portion 43 of the inner can 40.
[0022] Furthermore, the negative electrode current collector pin 64, which is electrically connected to the negative electrode layer 62 of the power generation element 60 and located on the winding core of the power generation element 60, is provided to be connected to the inner surface of the sealing plate 10 that seals the opening 33 of the outer can 30 (the surface facing the bottom 32 of the outer can 30). This ensures that the negative electrode layer 62 of the power generation element 60 is electrically connected to the sealing plate 10.
[0023] A predetermined non-aqueous electrolyte is injected into the outer casing 30, which houses the insulating plate 50, the power generation element 60, and the inner casing 40. For example, the non-aqueous electrolyte of the cylindrical battery 1 is a non-aqueous organic electrolyte obtained by dissolving a lithium salt in a non-aqueous solvent. A sealing plate 10, with a gasket 20 provided on its outer edge 11, is provided at the opening 33 of the outer casing 30 into which the non-aqueous electrolyte has been injected. The outer edge 11 of the sealing plate 10 and the gasket 20 provided thereon are placed on the bent portion 42 and flange portion 43 of the inner casing 40 and supported by the bent portion 42 and flange portion 43. That is, the bent portion 42 and flange portion 43 of the inner casing 40 function as seats for the outer edge 11 of the sealing plate 10 and the gasket 20. With the outer edge 11 of the sealing plate 10 and the gasket 20 supported by the bent portion 42 and flange portion 43 of the inner can 40, the opening edge 33a of the opening 33 of the outer can 30 is crimped to the side of the bent portion 42 and flange portion 43 of the inner can 40 via the outer edge 11 of the sealing plate 10 and the gasket 20. As a result, the outer edge 11 of the sealing plate 10 is sandwiched and fixed between the crimped opening edge 33a of the outer can 30 and the bent portion 42 and flange portion 43 of the inner can 40 via the gasket 20, and the opening 33 of the outer can 30 is sealed and airtight by the sealing plate 10 and the gasket 20.
[0024] Furthermore, as an alternative configuration that does not use the inner can 40 as described above, a beading portion is provided around the vicinity of the opening edge 33a of the outer can 30 by drawing, and the outer edge 11 of the sealing plate 10 and the gasket 20 are placed on this beading portion as a seat, and the opening edge 33a of the outer can 30 is crimped to seal the opening 33. However, when the cylindrical battery 1 is made to be relatively small, for example, when the diameter of the outer can 30 and the height from the bottom 32 of the outer can 30 to the sealing plate 10 are made to be about 10 mm, it is difficult to provide the above-mentioned beading portion on the outer can 30. If a beading portion is provided on an outer can 30 of such size, the internal volume of the battery may be significantly reduced, or the size of the power generation element 60 that can be housed inside the battery may be restricted, which may result in insufficient battery performance.
[0025] Therefore, in the cylindrical battery 1 (Figure 1), instead of providing a beading portion on the outer casing 30, the inner casing 40 described above is housed inside the outer casing 30. The outer edge 11 of the sealing plate 10 and the gasket 20 are placed on the bent portion 42 and flange portion 43 provided on the inner casing 40, and the opening edge 33a of the outer casing 30 is crimped to seal the opening 33. In this way, if a beading portion is not provided, it can be said that the inner wall surface 31a of the outer casing 30, from its bottom 32 to the crimped opening edge 33a, is located outside the outermost edge of the gasket 20 in the radial direction of the outer casing 30.
[0026] By using an inner can 40 instead of providing a beading section on the outer can 30, it becomes possible to achieve sufficient battery performance even when the cylindrical battery 1 is made relatively small, while avoiding the reduction in internal volume and the size constraints of the power generation element 60 mentioned above. Furthermore, this method of using an inner can 40 is applicable not only when the cylindrical battery 1 is relatively small, but also when it is medium or large in size.
[0027] As shown in Figure 1, the inner can 40 of the cylindrical battery 1 having the above configuration is provided with a hardened insulating resin 80 on the side of its bent portion 42 and flange portion 43 that is opposite to the outer edge portion 11 of the sealing plate 10 and the gasket 20, i.e., on the inside of the inner can 40. The insulating resin 80 is provided in a region on the inside of the inner can 40 that spans from the flange portion 43 through the bent portion 42 (the R portion at the base of the flange portion 43) to a part of the side wall portion 41. For example, the insulating resin 80 is provided such that the thickness of the insulating resin 80 provided on the bent portion 42 of the inner can 40 is greater than the thickness of the insulating resin 80 provided on the flange portion 43 of the inner can 40.
[0028] The insulating resin 80 provided on the bent portion 42 and flange portion 43 of the inner can 40 functions as a reinforcing member that suppresses deformation of the bent portion 42 and flange portion 43 in response to the pressing force from the outer edge portion 11 of the sealing plate 10 and the gasket 20 supported by the inner can 40. In other words, by providing the insulating resin 80 on the bent portion 42 and flange portion 43 of the inner can 40, when the opening edge portion 33a of the outer can 30 is crimped via the outer edge portion 11 of the sealing plate 10 and the gasket 20, the bending of the bent portion 42 due to the pressing force is suppressed, preventing the flange portion 43 from deforming toward the bottom portion 32 of the outer can 30 or from deforming excessively. If insulating resin 80 is provided on the bent portion 42 and flange portion 43 of the inner can 40 such that the bent portion 42 is thicker, then deformation of the flange portion 43 toward the bottom 32 side of the outer can 30, or excessive deformation, can be suppressed more effectively.
[0029] The effect of the insulating resin 80 on suppressing deformation of the inner can 40 when crimping the opening edge 33a of the outer can 30 will be explained further. Figure 2 illustrates an example of a manufacturing method for cylindrical batteries. Figures 2(A) and 2(B) schematically show enlarged cross-sectional views of key parts during the crimping process of the opening edge of the outer casing. Figures 2(A) and 2(B) also schematically show enlarged cross-sectional views of the crimping process corresponding to part P1 in Figure 1.
[0030] In the manufacture of a cylindrical battery 1 having the configuration shown in Figure 1 above, first, each element constituting the cylindrical battery 1, namely the sealing plate 10, gasket 20, outer casing 30, inner casing 40 (also called inner casing 40 with insulating resin 80) equipped with insulating resin 80, insulating plate 50, power generation element 60, and non-aqueous electrolyte, etc., are prepared.
[0031] An insulating plate 50 is placed on the bottom 32 of the outer can 30 through the opening 33, and the wound power generation element 60 and the inner can 40 with insulating resin 80 that houses it are inserted on top of the insulating plate 50. After the non-aqueous electrolyte is injected, a sealing plate 10 is placed to close the opening 33 of the outer can 30. The sealing plate 10 is provided such that its outer edge 11 and the gasket 20 covering it are placed on the bent portion 42 and flange portion 43 of the inner can 40 and supported by the bent portion 42 and flange portion 43.
[0032] From this state, a sealing die is used, and pressure is applied to the outer can 30 from the opening 33 side toward the bottom 32 side. As a result, as shown in Figure 2(A) or Figure 2(B), the opening edge 33a of the outer can 30 is crimped to the bent portion 42 and flange portion 43 of the inner can 40 that support the outer edge 11 and gasket 20 of the sealing plate 10.
[0033] Through this process, a cylindrical battery 1 having the configuration shown in Figure 1 and Figure 2(A) or Figure 2(B) above is manufactured. In the manufacturing of the cylindrical battery 1, when the opening edge 33a of the outer casing 30 is crimped, pressure is applied by the sealing die, which causes a pressing force to act on the bent portion 42 and flange portion 43 of the inner casing 40 from the outer edge 11 of the sealing plate 10 and the gasket 20 towards the bottom 32 of the outer casing 30 (or the side of the power generation element 60 housed inside).
[0034] In this case, in the cylindrical battery 1, a hardened insulating resin 80 is provided on the side of the bent portion 42 and flange portion 43 of the inner can 40 that is opposite to the outer edge 11 of the sealing plate 10 and the gasket 20. This insulating resin 80 functions as a reinforcing member, supporting the bent portion 42 and flange portion 43 against the pressing force from the outer edge 11 of the sealing plate 10 and the gasket 20, and preventing the bent portion 42 and flange portion 43 from deforming toward the bottom 32 side of the outer can 30 (or the power generation element 60 side) or from deforming excessively. If the thickness of the insulating resin 80 provided on the bent portion 42 is made thicker than the thickness of the insulating resin 80 provided on the flange portion 43, the bending or excessive bending of the bent portion 42 in response to the pressing force will be suppressed more effectively, and the deformation or excessive deformation of the bent portion 42 and the flange portion 43 extending from there will be suppressed more effectively.
[0035] For example, as shown in Figure 2(A), by providing insulating resin 80 to the bent portion 42 and flange portion 43 of the inner can 40, deformation of the bent portion 42 and flange portion 43 toward the power generation element 60 side (the bottom portion 32 side of the outer can 30) is suppressed in response to the pressing force when the opening edge portion 33a of the outer can 30 is crimped.
[0036] Alternatively, as shown in Figure 2(B), by providing insulating resin 80 to the bent portion 42 and flange portion 43 of the inner can 40, excessive deformation of the bent portion 42 and flange portion 43 toward the power generation element 60 (the bottom portion 32 of the outer can 30) in response to the pressing force when the opening edge portion 33a of the outer can 30 is crimped is suppressed. For example, the deformation of the bent portion 42 and flange portion 43 is suppressed to the extent that the tip 43a on the inner surface of the flange portion 43 reaches the power generation element 60.
[0037] Furthermore, if the bent portion 42 and flange portion 43 of the inner can 40 deform, the tip 43a on the inner surface of the flange portion 43 will be located closer to the bottom 32 side (towards the power generation element 60) of the outer can 30 than the inner surface position 42a of the bent portion 42, which corresponds to the original height position before deformation.
[0038] Here, we will describe the case in which insulating resin 80 is not provided on the bent portion 42 and flange portion 43 of the inner can 40. If insulating resin 80 is not provided on the bent portion 42 and flange portion 43 of the inner can 40, sufficient reinforcement against the pressing force from the outer edge portion 11 of the sealing plate 10 and the gasket 20 cannot be obtained. As a result, deformation of the bent portion 42 and flange portion 43, that is, deformation of the bent portion 42 and flange portion 43 toward the bottom portion 32 of the outer can 30 (or toward the power generation element 60 housed inside) becomes more likely.
[0039] The inner casing 40 houses a power generation element 60 having electrode layers of different polarities, a positive electrode layer 61 and a negative electrode layer 62. The inner casing 40 is in contact with one of the electrode layers of the power generation element 60, the positive electrode layer 61 in this example, and is electrically connected to the positive electrode layer 61. That is, the inner casing 40 (its sidewall portion 41, bent portion 42, and flange portion 43) has positive polarity.
[0040] When the bending portion 42 and flange portion 43 of the inner can 40 deform toward the bottom portion 32 of the outer can 30 due to the pressing force from the outer edge 11 of the sealing plate 10 and the gasket 20, depending on the amount of deformation, the deformed inner can 40 (for example, its flange portion 43) may come into contact with the power generation element 60 it houses (the outer circumference facing the flange portion 43). If the deformed inner can 40 comes into contact with an electrode layer of the power generation element 60 having a polarity different from that of the inner can 40, in this example the negative electrode layer 62, a short-circuit failure will occur.
[0041] Furthermore, if the pressing force from the outer edge 11 of the sealing plate 10 and the gasket 20 causes the bent portion 42 and flange portion 43 of the inner can 40 to deform toward the bottom portion 32 of the outer can 30, depending on the amount of deformation, the deformation of the gasket 20 may become uneven, and it may become impossible to maintain the seal provided by the gasket 20.
[0042] To prevent contact between the electrode layer and the inner can 40 due to deformation, in this example, contact with the negative electrode layer 62, it is conceivable to reduce the pressing force from the outer edge 11 of the sealing plate 10 and the gasket 20, that is, to reduce the pressure applied by the sealing mold. However, doing so may result in insufficient sealing function of the gasket 20, making it easier for the non-aqueous electrolyte injected into the outer can 30 to leak.
[0043] Thus, if insulating resin 80 is not provided on the bent portion 42 and flange portion 43 of the inner can 40, attempting to crimp the opening edge 33a of the outer can 30 with sufficient pressure to suppress liquid leakage will easily cause excessive deformation of the outer edge 11 of the sealing plate 10 and the bent portion 42 and flange portion 43 that support the gasket 20. As a result, contact with electrode layers of different polarity of the power generation element 60 or a decrease in sealing performance due to irregular deformation of the gasket 20 may occur. Conversely, if the pressure applied during crimping is reduced to suppress contact between the inner can 40 and the electrode layers of the power generation element 60 of different polarity or a decrease in sealing performance due to irregular deformation of the gasket 20, the crimping may be insufficient, the gasket 20 may not provide sufficient sealing function, and liquid leakage may easily occur.
[0044] In contrast, in the cylindrical battery 1 shown in Figures 1 and 2(A) or 2(B) above, a hardened insulating resin 80 is provided on the side of the inner can 40 opposite to the outer edge 11 of the sealing plate 10 and the gasket 20, at the bent portion 42 and the flange portion 43. The insulating resin 80 is provided such that, for example, the thickness of the insulating resin 80 provided at the bent portion 42 is greater than the thickness of the insulating resin 80 provided at the flange portion 43.
[0045] The provision of insulating resin 80 reinforces the strength of the bent portion 42 and flange portion 43 of the inner can 40 against the pressing force from the outer edge 11 of the sealing plate 10 and the gasket 20, thereby suppressing deformation or excessive deformation of the bent portion 42 and flange portion 43 of the inner can 40 toward the bottom 32 of the outer can 30. That is, as shown in Figure 2(A) or Figure 2(B), deformation or excessive deformation of the bent portion 42 and flange portion 43 of the inner can 40 toward the power generation element 60 is suppressed. Therefore, contact between the deformed inner can 40 (for example, its flange portion 43) and the electrode layer (for example, the negative electrode layer 62) of the power generation element 60 with a different polarity is suppressed, and short-circuit failures are suppressed. Since the inner can 40 is provided with insulating resin 80 on the inner surface of its bent portion 42 and flange portion 43 that faces the power generation element 60, even if the inner can 40 deforms excessively toward the power generation element 60, direct contact between the inner can 40 and the electrode layer (e.g., negative electrode layer 62) of the power generation element 60 is suppressed, and short-circuit failures are suppressed.
[0046] Furthermore, the provision of insulating resin 80 suppresses deformation or excessive deformation of the bent portion 42 and flange portion 43 of the inner can 40 toward the power generation element 60, thereby suppressing the deformation of the gasket 20 due to the pressing force from the outer edge portion 11 of the sealing plate 10 and the gasket 20, and preventing the gasket 20 from losing its sealing ability. The opening edge portion 33a of the outer can 30 can be crimped with sufficient or greater pressing force while suppressing excessive deformation of the bent portion 42 and flange portion 43 of the inner can 40 toward the power generation element 60, and preventing the gasket 20 from deforming irregularly, thereby suppressing leakage of the non-aqueous electrolyte injected into the inside of the outer can 30.
[0047] By providing insulating resin 80 to the bent portion 42 and the flange portion 43 of the inner can 40, and further by providing the insulating resin 80 such that the bent portion 42 is thicker than the flange portion 43, a high-performance, high-quality cylindrical battery 1 can be realized.
[0048] Further details will be given regarding the insulating resin 80. A thermosetting resin exhibiting insulating properties can be used for the insulating resin 80 provided in the bent portion 42 and flange portion 43 of the inner can 40. For example, epoxy resin can be used as the insulating resin 80. The resin material of the insulating resin 80 may contain additives such as a curing agent. In addition to thermosetting resins, a photocurable resin that hardens when exposed to light such as ultraviolet light may also be used for the insulating resin 80 provided in the bent portion 42 and flange portion 43 of the inner can 40.
[0049] In order to suppress deformation or excessive deformation of the bent portion 42 and flange portion 43 of the inner can 40 as described above by the insulating resin 80, it is preferable to use a resin material that exhibits relatively high hardness in the cured state for the insulating resin 80. For example, a resin material having a pencil hardness of 3H or higher, more preferably 5H or higher, in the cured state is used to form the insulating resin 80. By forming the insulating resin 80 on the inner can 40 using a predetermined resin material that exhibits a predetermined hardness in the cured state, deformation or excessive deformation due to the pressing force applied to the outer edge 11 of the sealing plate 10 and the gasket 20 when crimping the opening edge 33a of the outer can 30 can be effectively suppressed.
[0050] In order to effectively suppress deformation or excessive deformation of the bent portion 42 and flange portion 43 of the inner can 40 in response to pressing force, it is preferable that the insulating resin 80 provided on the bent portion 42 is thicker than the insulating resin 80 provided on the flange portion 43.
[0051] Here, Figure 3 illustrates the thickness of the insulating resin provided in the inner can. Figures 3(A) and 3(B) schematically show cross-sectional views of the main parts of the inner can where the insulating resin is provided. As shown in Figures 3(A) and 3(B), the inner can 40 has a side wall portion 41, a bent portion 42, and a flange portion 43. The side wall portion 41 is the portion that extends along the inner wall surface 31a of the outer can 30 as described above. The bent portion 42 is the portion that bends inward from the end of the side wall portion 41 into the inner can 40. The flange portion 43 is the portion that extends inward from the bent portion 42 into the inner can 40. The bent portion 42 is the base portion of the flange portion 43 and is an R portion with an R-shaped inner surface. Here, the portion P2 (dotted line frame portion), which is the portion that bends (for example, bends 90°) from the direction D1 in which the side wall portion 41 extends to the direction D2 in which the flange portion 43 extends, is called the bent portion 42.
[0052] An insulating resin 80 is provided on the inside of the bent portion 42 and the flange portion 43 of the inner can 40. The insulating resin 80 is provided on the inside of the inner can 40 in an area that spans from the flange portion 43 through the bent portion 42 (the R portion at the base of the flange portion 43) to a part of the side wall portion 41.
[0053] Furthermore, the outer edge 11 of the sealing plate 10 and the gasket 20 are provided on the side of the inner can 40 opposite to the side where the insulating resin 80 is provided, i.e., on the outside of the bent portion 42 and the flange portion 43.
[0054] The insulating resin 80 provided in the bent portion 42 and flange portion 43 of the inner can 40 is provided such that, for example, the thickness of the insulating resin 80 provided in the bent portion 42 is greater than the thickness of the insulating resin 80 provided in the flange portion 43. For example, as shown in Figure 3(A), the insulating resin 80 is provided such that the thickness T1 (which may become thinner as it moves away from the center of the bent portion 42) in the direction D3 of the bent portion 42, where the angle between the direction D1 in which the side wall portion 41 extends and the direction D2 in which the flange portion 43 extends is equal, is greater than the thickness T2 in the flange portion 43 in the direction D1. Alternatively, as shown in Figure 3(B), the insulating resin 80 is provided such that the thickness T3 in the direction D1 of the bent portion 42 is greater than the thickness T2 in the direction D1 of the flange portion 43 (which may be thicker in areas closer to the bent portion 42 than in areas further away).
[0055] In this way, the insulating resin 80 can be provided such that the thickness of the insulating resin 80 provided in the bent portion 42 is greater than the thickness of the insulating resin 80 provided in the flange portion 43. Such an insulating resin 80 can be formed, for example, by applying a predetermined resin material exhibiting fluidity, as described above, to the inside of the bent portion 42 and flange portion 43 of the inner can 40, and then drying and curing it. In this case, the application of the resin material may be repeated multiple times, followed by drying and curing to form an insulating resin 80 having predetermined thicknesses T1 and T2, or an insulating resin 80 having predetermined thicknesses T3 and T2. Alternatively, the series of steps of applying the resin material, drying, and curing may be repeated multiple times to form an insulating resin 80 having predetermined thicknesses T1 and T2, or an insulating resin 80 having predetermined thicknesses T3 and T2.
[0056] Next, examples and comparative examples will be described. In the following comparative examples and Examples 1-4, the pencil hardness of the insulating resin 80, the amount of flange deformation [mm], and the short-circuit failure rate [%] were measured for cylindrical batteries manufactured without insulating resin 80 in the inner casing 40 (comparative example) and cylindrical batteries manufactured with insulating resin 80 in the inner casing 40 (Examples 1-4).
[0057] Here, five cylindrical batteries were fabricated for each of the comparative examples and Examples 1-4. The pencil hardness of the insulating resin 80 was measured in the hardened state by a pencil scratch test in accordance with JIS K-5600. The deformation of the flange portion was measured using a microscope, by measuring the change from the initial position of the tip 43a of the flange portion 43 before crimping (corresponding to the inner surface position 42a of the bent portion 42). The short-circuit failure rate was measured based on electrical tests of the fabricated cylindrical batteries.
[0058] (Comparative example) A cylindrical battery was fabricated in which the inner casing 40 was not provided with insulating resin 80. Five cylindrical batteries were fabricated using the inner casing 40 without the insulating resin 80.
[0059] (Example 1) A cylindrical battery was fabricated in which insulating resin 80 was provided on the bent portion 42 and the flange portion 43 of the inner casing 40 so that they were of equal thickness. The insulating resin 80 used had a pencil hardness of 7H in its cured state. Five cylindrical batteries were fabricated using the inner casing 40 with this insulating resin 80.
[0060] (Example 2) A cylindrical battery was fabricated in which insulating resin 80 was provided on the bent portion 42 and flange portion 43 of the inner casing 40 such that the bent portion 42 was thicker than the flange portion 43. The insulating resin 80 used had a pencil hardness of 7H in its cured state. Five cylindrical batteries were fabricated using the inner casing 40 with this insulating resin 80.
[0061] (Example 3) A cylindrical battery was fabricated in which insulating resin 80 was provided on the bent portion 42 and flange portion 43 of the inner casing 40 such that the bent portion 42 was thicker than the flange portion 43. The insulating resin 80 used had a pencil hardness of 5H in its cured state. Five cylindrical batteries were fabricated using the inner casing 40 with this insulating resin 80.
[0062] (Example 4) A cylindrical battery was fabricated in which insulating resin 80 was provided on the bent portion 42 and flange portion 43 of the inner casing 40 such that the bent portion 42 was thicker than the flange portion 43. The insulating resin 80 used had a pencil hardness of 3H in its cured state. Five cylindrical batteries were fabricated using the inner casing 40 with this insulating resin 80.
[0063] Table 1 shows the measurement results obtained for the cylindrical batteries prepared in the comparative example and Examples 1-4. The flange deformation amount [mm] in Table 1 represents the average value of the flange deformation amount measured for the five cylindrical batteries in each of the comparative example and Examples 1-4. The short-circuit failure rate [%] in Table 1 represents the rate of short-circuit failures occurring in the five cylindrical batteries in each of the comparative example and Examples 1-4.
[0064] [Table 1]
[0065] Table 1 shows that in the comparative example where the insulating resin 80 is not provided on the inner can 40, the deformation of the flange portion is relatively large at 0.306 mm, and the short-circuit failure rate is also relatively large at 54.1%. In a configuration like the comparative example, the pressing force during crimping causes the inner can 40 to deform relatively significantly, making it easier for it to come into contact with the electrode layer (negative electrode layer 62) of the opposing power generation element 60, which has a different polarity from the inner can 40, and thus prone to short-circuit failures.
[0066] In Example 1, insulating resin 80 is provided on both the bent portion 42 and the flange portion 43 of the inner can 40 to have the same thickness, resulting in flange deformation of 0.241 mm and a short-circuit failure rate of 4.4%, both of which are lower than in the comparative example. The provision of insulating resin 80 suppresses contact with the power generation element 60 caused by excessive deformation of the inner can 40, and the resulting short-circuit failure.
[0067] In Examples 2-4, where insulating resin 80 is provided on the bent portion 42 and flange portion 43 of the inner can 40 such that the bending portion 42 is thicker than the flange portion 43, for example, in Example 2, the flange deformation is 0.063 mm and the short-circuit failure rate is 0.1%. In Example 3, the flange deformation is 0.091 mm and the short-circuit failure rate is 0.0%. In Example 4, the flange deformation is 0.144 mm and the short-circuit failure rate is 1.2%. In Examples 2-4, both the flange deformation and the short-circuit failure rate are kept lower than in the Comparative Example and Example 1. By providing insulating resin 80, and by providing insulating resin 80 such that the bending portion 42 is thicker than the flange portion 43, it is possible to suppress the deformation of the inner can 40 itself, and it can be said that it is possible to effectively suppress contact with the power generation element 60 caused by excessive deformation of the inner can 40, and the occurrence of short-circuit failures caused thereby.
[0068] From the results of Examples 2-4 in Table 1, it can be said that the effect of suppressing deformation of the flange portion 43 of the inner can 40 increases as the pencil hardness of the insulating resin 80 increases. In particular, when the pencil hardness of the insulating resin 80 is set to 5H or higher, it becomes possible to suppress the amount of deformation of the flange portion to a low value of 0.1 mm or less, and the short-circuit failure rate can also be kept at a sufficiently low value.
[0069] In the above explanation, an example configuration was given in which the inner can 40 and outer can 30 are electrically connected to the positive electrode layer 61 of the power generation element 60, and the sealing plate 10 is electrically connected to the negative electrode layer 62 of the power generation element 60. However, it is also possible to configure the inner can 40 and outer can 30 to be electrically connected to the negative electrode layer 62 of the power generation element 60, and the sealing plate 10 to be electrically connected to the positive electrode layer 61 of the power generation element 60. In this case as well, the same effect as described above can be obtained by providing the insulating resin 80 in the inner can 40 as described above.
[0070] Furthermore, although the above explanation uses the example of a lithium primary battery as the cylindrical battery 1, the cylindrical battery 1 can also be a lithium secondary battery. When the cylindrical battery 1 is a lithium secondary battery, lithium cobalt oxide or the like is used as the positive electrode active material in the positive electrode layer 61 of the power generation element 60, and lithium metal or lithium alloy or the like is used as the negative electrode active material in the negative electrode layer 62 of the power generation element 60. A non-aqueous organic electrolyte is used, which is obtained by dissolving a lithium salt in a non-aqueous solvent.
[0071] Furthermore, the method of providing the insulating resin 80 in the inner can 40 as described above is applicable not only when the cylindrical battery 1 is relatively small, but also when it is medium or large in size, thereby achieving the same effects as described above. [Explanation of Symbols]
[0072] 1. Cylindrical battery 1a Deformation Analysis Model 10 Sealing plate 11 Outer edge 20 gaskets 30 outer cans 31, 41 Side wall section 31a, 41a Inner wall surface 32 Bottom 33 Aperture 33a Opening edge 40 inner cans 42. Bending section 42a Inner surface position 43 Guard section 43a Tip 50 Insulating board 60 Power Generation Elements 61 Positive electrode layer 62 Negative electrode layer 63 Separator 64 Negative current collector pin 70 Sealing mold 80 Insulating resin D1, D2, D3 direction S1, S2, S3 flange deformation amount T1, T2, T3 thickness
Claims
1. Sealing plate and A gasket covering the outer edge of the sealing plate, A bottomed outer can having an opening that is sealed by the sealing plate, An inner can housed inside the outer can, having a side wall portion extending along the inner wall surface of the outer can, and a flange portion extending inward from the end of the side wall portion on the opening side via a bent portion, Includes, The opening edge of the outer can is crimped to the side of the bent portion and flange portion of the inner can via the outer edge of the sealing plate and the gasket. The inner can is a cylindrical battery having insulating resin fixed to the inner surface of the bent portion and the flange portion, on the side opposite to the outer edge of the sealing plate and the gasket.
2. The cylindrical battery according to claim 1, wherein the thickness of the insulating resin provided in the bent portion is greater than the thickness of the insulating resin provided in the flange portion.
3. The cylindrical battery according to claim 1, wherein the insulating resin is a thermosetting resin.
4. The cylindrical battery according to claim 1, wherein the insulating resin is an epoxy resin.
5. The cylindrical battery according to claim 1, wherein the insulating resin has a pencil hardness of 3H or higher.
6. The cylindrical battery according to claim 1, wherein the tip of the flange portion of the inner can is located on the inner surface of the bent portion or on the bottom side of the outer can than the inner surface of the bent portion.
7. The cylindrical battery according to claim 1, wherein the inner wall surface of the outer casing, from the bottom of the outer casing to the crimped opening edge, is located outside the outermost edge of the gasket in the radial direction of the outer casing.