Battery

Abstract

To provide a more miniaturized battery.SOLUTION: A battery includes: a battery element body including a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode; a housing that houses the battery element body and is provided with an opening; and a positive electrode terminal that is disposed outside the housing, is joined to an edge portion of the opening with an adhesive layer interposed therebetween in a state of covering the opening, and includes aluminum or an aluminum alloy. The housing is electrically connected to the negative electrode of the battery element body. In the positive electrode terminal, when viewed from a direction intersecting the edge portion of the opening, a first portion overlapping the opening is electrically connected to the positive electrode of the battery element body, and an anodic oxide coating is provided at a portion of the positive electrode terminal facing the adhesive layer.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a battery. [Background technology]

[0002] Patent Document 1 discloses a secondary battery including a rivet that serves as a positive terminal and a gasket that is crimped to the rivet. Specifically, the rivet (positive terminal) has a plate portion and a pin that protrudes from the plate portion. After the pin is inserted into a through-hole in the gasket, the tip of the pin is crushed and deformed to crimp the rivet to the gasket. The rivet, gasket, and battery element are housed inside a housing.

[0003] The secondary battery described in Patent Document 2 includes a battery body and an exterior case that houses the battery body. The negative electrode body of the battery body is connected to the exterior case. An insertion hole is provided through the exterior case, and a lead body connected to the positive electrode body of the battery body is inserted into the insertion hole. A flat electrode terminal that is disposed on the outside of the exterior case and covers the insertion hole is connected to the lead body. The flat electrode terminal and the outer surface of the exterior case are joined via a sealing member.

[0004] The secondary battery described in Patent Document 3 includes a heat-sealed battery case and aluminum terminals protruding from the battery case, with an alumite layer provided on the surface of the aluminum terminals, which improves adhesion between the inner film of the battery case and the terminals.

[0005] Patent Document 4 discloses a secondary battery having a bipolar electrode. The bipolar electrode has a positive electrode active material layer provided on one surface of a current collector and a negative electrode active material layer provided on the other surface of the current collector. The battery element has multiple bipolar electrodes stacked one on top of the other. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] US Patent Application Publication No. 2019 / 0341587 [Patent Document 2] Japanese Patent Application Publication No. 2019-46639 [Patent Document 3] Japanese Patent Application Laid-Open No. 2000-149913 [Patent Document 4] Japanese Patent Application Laid-Open No. 2005-310402 Summary of the Invention [Problem to be solved by the invention]

[0007] In recent years, there has been a demand for smaller batteries.

[0008] The present invention has been made in view of the above, and has an object to provide a battery that is more compact. [Means for solving the problem]

[0009] A battery according to one aspect of the present invention comprises: a battery body including a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode; a casing that houses the battery body and has an opening; a positive electrode terminal that covers the opening and is disposed on the outside of the casing; and an adhesive layer that joins the casing and the positive electrode terminal, wherein the positive electrode and the positive electrode terminal are electrically connected, and a portion of the positive electrode terminal that faces the adhesive layer has an anodized coating. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a more compact battery. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing a cross section of a battery according to a first embodiment. [Figure 2] FIG. 2 is a schematic diagram of the battery of FIG. 1 disassembled. [Figure 3] FIG. 3 is a schematic enlarged cross-sectional view of a portion of FIG. [Figure 4] FIG. 4 is a rear view of the positive electrode terminal according to the first embodiment, as viewed from the back surface side. [Figure 5] FIG. 5 is a schematic diagram showing a cross section of a battery according to the second embodiment. [Figure 6] FIG. 6 is a schematic diagram showing an enlarged portion of FIG. [Figure 7] FIG. 7 is a cross-sectional view showing a positive electrode terminal according to a first modified example. [Figure 8] FIG. 8 is a cross-sectional view showing a positive electrode terminal according to a second modified example. DETAILED DESCRIPTION OF THE INVENTION

[0012] The following describes the embodiments in detail with reference to the drawings. However, the present invention is not limited to these embodiments. Each embodiment is an example, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments is possible. From the second embodiment onwards, a description of matters common to the first embodiment will be omitted, and only the differences will be described. In particular, similar effects resulting from similar configurations will not be mentioned in each embodiment.

[0013] [First embodiment] First, the battery according to the first embodiment will be described. Fig. 1 is a schematic diagram showing a cross section of the battery according to the first embodiment. Fig. 2 is a schematic diagram in which the battery of Fig. 1 is disassembled. Fig. 3 is a schematic diagram in which a cross section of a part of Fig. 2 is enlarged. Fig. 4 is a rear view of the positive electrode terminal according to the first embodiment as seen from the back side.

[0014] 1 and 2 is, for example, a chemical battery including a secondary battery. For example, a lithium-ion secondary battery can be used as the secondary battery. However, the battery according to the present invention is not limited to a secondary battery, and various other batteries can be used.

[0015] As shown in FIGS. 1 and 2, the battery 100 includes a battery body 1, a housing 2, and a positive electrode terminal 3.

[0016] 1, the battery body 1 includes a positive electrode 11, a negative electrode 12, and a separator 13. Specifically, the separator 13 is interposed between the positive electrode 11 and the negative electrode 12. That is, in the battery body 1, the positive electrode 11, the separator 13, and the negative electrode 12 are arranged in this order.

[0017] The battery element 1 may be a wound body in which the positive electrode 11 and the negative electrode 12 are stacked together with a separator 13 interposed therebetween, and the positive electrode 11, the negative electrode 12, and the separator 13 are wound together. Alternatively, the battery element 1 may be a laminate in which the positive electrode 11 and the negative electrode 12 are stacked together with the separator 13 interposed therebetween.

[0018] (positive electrode) The positive electrode 11 includes a positive electrode current collector and a positive electrode active material layer. The positive electrode current collector is a conductive support that supports the positive electrode active material layer and has a pair of surfaces on which the positive electrode active material layer is provided. The positive electrode current collector includes a conductive material such as a metal material, and the metal material is aluminum or the like. The positive electrode active material layer may be provided on both surfaces of the positive electrode current collector or on one surface.

[0019] The positive electrode active material layer contains one or more positive electrode active materials capable of absorbing and releasing lithium. The positive electrode active material layer may further contain one or more positive electrode binders and positive electrode conductive agents. The method for forming the positive electrode active material layer is not particularly limited, but may be, for example, a coating method.

[0020] The positive electrode active material contains a lithium compound because it can provide a high energy density. The lithium compound is a compound containing lithium as a constituent element, more specifically, a compound containing lithium and one or more transition metal elements as constituent elements. However, the lithium compound may further contain one or more elements other than the lithium and the transition metal elements.

[0021] The type of lithium compound is not particularly limited, but specific examples include oxides, phosphate compounds, silicate compounds, and borate compounds. Specific examples of oxides include LiNiO2, LiCoO2, and LiMn2O4. Specific examples of phosphate compounds include LiFePO4 and LiMnPO4.

[0022] The positive electrode binder contains one or more of synthetic rubber and polymer compounds. The synthetic rubber is styrene-butadiene rubber, and the polymer compound is polyvinylidene fluoride. The positive electrode conductor contains one or more of conductive materials such as carbon materials, and the carbon materials include graphite, carbon black, acetylene black, and ketjen black. However, the conductive material may also be a metal material or a polymer compound.

[0023] (Negative electrode) The negative electrode 12 includes a negative electrode current collector and a negative electrode active material layer. The negative electrode current collector is a conductive support that supports the negative electrode active material layer and has a pair of surfaces on which the negative electrode active material layer is provided. The negative electrode current collector includes a conductive material such as a metal material, and the metal material is copper or the like. The negative electrode active material layer may be provided on both surfaces or one surface of the negative electrode current collector.

[0024] The negative electrode active material layer contains one or more types of negative electrode active materials capable of absorbing and releasing lithium. The negative electrode active material layer may further contain one or more types of materials such as a negative electrode binder and a negative electrode conductor. Details regarding the negative electrode binder and the negative electrode conductor are the same as those regarding the positive electrode binder and the positive electrode conductor. The method for forming the negative electrode active material layer is not particularly limited, but specifically includes one or more types of coating, vapor phase, liquid phase, thermal spraying, and firing (sintering) methods.

[0025] The negative electrode active material contains one or both of a carbon material and a metal-based material. This is because a high energy density can be obtained. Carbon materials include graphitizable carbon, non-graphitizable carbon, and graphite (natural graphite and artificial graphite). Metal-based materials are materials containing one or more metal elements and semi-metal elements that can form an alloy with lithium as constituent elements, and specific examples of the metal element and semi-metal element include one or both of silicon and tin. However, the metal-based material may be a simple substance, an alloy, a compound, a mixture of two or more of these, or a material containing two or more of these phases. Specific examples of metal-based materials are TiSi2 and SiOx(0 <x≦2または0.2<x<1.4)などである。

[0026] (separator) The separator 13 is an insulating porous film interposed between the positive electrode 11 and the negative electrode 12, and allows lithium ions to pass through while preventing contact (short circuit) between the positive electrode 11 and the negative electrode 12. The separator 13 contains a polymer compound such as polyethylene.

[0027] (electrolyte) The electrolyte solution is impregnated into each of the positive electrode 11, the negative electrode 12, and the separator 13, and contains a solvent and an electrolyte salt. The solvent contains one or more of non-aqueous solvents (organic solvents) such as carbonate ester compounds, carboxylic acid ester compounds, and lactone compounds, and the electrolyte solution containing the non-aqueous solvent is a so-called non-aqueous electrolyte solution. The electrolyte salt contains one or more of light metal salts such as lithium salts.

[0028] As shown in FIG. 1 , the housing 2 has a housing body 21 and a lid 22 and houses the battery element 1. The housing 2 contains Fe, Ni, stainless steel, Cu, or any of these materials plated with Ni. The housing body 21 has a bottom 212 and a side 211. The bottom 212 has a circular shape centered on a center O, and the side 211 has a cylindrical shape extending in the circumferential direction around the center O. The side 211 extends upward from the end of the bottom 212. The housing body 21 has a U-shaped cross section and is open at the top. The lid 22 is joined to an upper end 213 of the side 211. Specifically, an outer peripheral end 223 of the lid 22 is joined to the upper end 213 of the side 211. The lid 22 has an annular shape centered on the center O. A circular opening 220 is provided in the center of the lid 22. The opening 220 faces the inside (inner circumferential side) of the inner wall 222. The bottom 212 of the housing 2 is connected to the negative electrode 12 of the battery element 1 via a wiring 121. The housing body 21 and the lid 22 may be integrally molded.

[0029] 1, a positive electrode terminal 3 is joined to the upper side of the lid 22. The positive electrode terminal 3 is disposed outside the housing 2 and is joined to the lid 22 in a state where it covers an opening 220 of the lid 22. In this way, the opening 220 is sealed by the positive electrode terminal 3. The positive electrode terminal 3 will be described in detail later.

[0030] As shown in FIG. 3 , the positive electrode terminal 3 includes a clad material 30 and an anodized coating 34. The clad material 30 includes a nickel material 31, a stainless steel material 32, and an aluminum material 33. Specifically, the stainless steel material 32 is joined to the back side (lower side) of the nickel material 31, and the aluminum material 33 is joined to the back side (lower side) of the stainless steel material 32. An anodized coating 34 is formed on the back side (lower side) of the aluminum material 33. The anodized coating 34 is also referred to as an alumite layer. The average thickness of the anodized coating 34 is 2 μm or more and 100 μm or less, and more preferably 10 μm or more and 50 μm or less. The Vickers hardness of the anodized coating 34 is, for example, HV300 or more.

[0031] An adhesive layer 35 is provided on the back side (lower side) of the anodic oxide coating 34. The adhesive layer 35 contains a polyolefin resin. The lid 22 has an upper surface 224 and a lower back surface 225. The surface 224 of the lid 22 and the anodic oxide coating 34 are bonded via the adhesive layer 35. Specifically, the anodic oxide coating 34 is bonded to the surface 224 of the lid 22, at an edge 221 of the opening 220, via the adhesive layer 35. The adhesive layer 35 is provided in a region from an inner peripheral edge 351 to an outer peripheral edge 352. Here, the adhesive layer 35 is provided on the back side (lower side) of the anodic oxide coating 34, but it may also be provided on the edge 221 of the opening 220. The edge 221 of the opening 220 refers to the region of the lid 22 from the inner wall 222 to the portion corresponding to the outer peripheral edge of the positive electrode terminal 3. The average distance between the anodic oxide coating 34 of the positive electrode terminal 3 and the edge 221 of the opening 220 in the housing 2 is greater than 0 μm and less than or equal to 30 μm. The average distance is the average value of measurements taken at four locations, for example, two locations each at approximately 20% and 80% from the inner wall 222 of the edge 221 in any cross section.

[0032] As shown in FIG. 4, the positive electrode terminal 3 has a circular shape centered at center O. A formation region 38, where the anodic oxide coating 34 is provided, is arranged in an annular shape on the outer periphery of the positive electrode terminal 3. The formation region 38 has an inner circumferential edge 341 and an outer circumferential edge 342. A circular non-formation region 39, where the anodic oxide coating 34 is not provided, is arranged on the inner periphery of the inner circumferential edge 341 of the formation region 38. Also, as shown in FIG. 4, the inner wall 222 of the lid 22 is indicated by a two-dot chain line, and the region inside this two-dot chain line is referred to as a first region 37. The first region 37 is a region of the positive electrode terminal 3 that overlaps with the opening 220 when viewed from the top-bottom direction. The first region 37 includes the non-formation region 39 of the anodic oxide coating 34.

[0033] Furthermore, since the aluminum material 33 is exposed in the non-forming region 39, the aluminum material 33 in the non-forming region 39 and the positive electrode 11 of the battery body 1 are electrically connected, as shown in FIGS. 1 and 3 . For example, an end 112 of a wire 111 electrically connected to the positive electrode 11 of the battery body 1 is connected to the aluminum material 33 in the non-forming region 39. Note that an end 113 of the wire 111 is connected to the positive electrode 11 of the battery body 1, as shown in FIGS. 1 and 2 . The wire 111 is a connection wire for the positive electrode 11 that connects the positive electrode 11 to the positive electrode terminal 3. The wire 121 is a connection wire for the negative electrode 12 that connects the negative electrode 12 to the casing 2. The wire 121 may be attached to the battery body 1 or may be led out from the battery body 1.

[0034] As described above, the battery 100 according to the first embodiment includes the battery body 1 including the positive electrode 11, the negative electrode 12, and the separator 13 disposed between the positive electrode 11 and the negative electrode 12; the casing 2 that houses the battery body 1 and has an opening 220; and the positive electrode terminal 3 that is disposed outside the casing 2 and is joined to the edge 221 of the opening 220 via the adhesive layer 35 while covering the edge 221, and that includes aluminum or an aluminum alloy. The casing 2 is electrically connected to the negative electrode 12 of the battery body 1, and the positive electrode terminal 3 is electrically connected to the positive electrode 11 of the battery body 1. An anodized coating 34 is formed on the portion of the positive electrode terminal 3 facing the adhesive layer 35.

[0035] An opening 220 is provided in the lid 22, which is a part of the housing 2, and the opening 220 is sealed by the positive terminal 3. The positive terminal 3 is provided with an anodic oxide coating 34. The anodic oxide coating 34 has high insulating properties and high strength, so the insulation between the positive terminal 3 and the lid 22 can be maintained even if the thickness of the adhesive layer 35 is reduced. As described above, according to this embodiment, the thickness of the adhesive layer 35 can be reduced compared to when the positive terminal 3 does not have the anodic oxide coating 34, thereby enabling the battery 100 to be made more compact. Furthermore, because the positive terminal 3 has the anodic oxide coating 34, there is no need to provide a new insulating layer, and the battery 100 can be made more compact. The thickness of the adhesive layer 35 is, for example, 5 μm to 200 μm, more preferably 10 μm to 150 μm.

[0036] The thickness of the anodic oxide coating 34 is 2 μm or more and 100 μm or less, and more preferably 10 μm or more and 50 μm or less.

[0037] If the thickness of the anodic oxide coating 34 is less than 2 μm, it may not be possible to ensure insulation between the positive electrode terminal 3 and the lid 22. If the thickness of the anodic oxide coating 34 is greater than 100 μm, the anodic oxide coating 34 becomes more susceptible to cracking, and the anodizing process takes longer, which may result in deformation of the positive electrode terminal 3. For these reasons, it is preferable that the thickness of the anodic oxide coating 34 be 2 μm or more and 100 μm or less. The thickness of the anodic oxide coating 34 is preferably, for example, one-third the thickness of the positive electrode terminal 3. Although an oxide coating is formed on the surface of aluminum by natural oxidation, the thickness of this oxide coating is, for example, 2 nm (nanometers), and does not exceed 2 μm, which is the thickness of the anodic oxide coating 34.

[0038] The positive electrode terminal 3 includes materials such as aluminum, aluminum alloys, and clad materials containing aluminum. Examples of aluminum and aluminum alloys include, but are not limited to, A1000, A2000, A3000, A4000, A5000, A6000, and A7000 series. Materials in the A3000, A1000, A5000, and A6000 series are preferred because they provide a coating hardness of HV450 or higher. The positive electrode terminal 3 preferably includes an aluminum alloy containing 93% or more by weight of Al and less than 6% by weight of impurities. Examples of impurities include less than 1% by weight of Fe, less than 1% by weight of Cu, less than 1% by weight of Zn, less than 1% by weight of Mn, and less than 2% by weight of Si.

[0039] If the amount of impurities other than Al is large, the impurities will ionize, making it difficult to form the anodic oxide coating 34. Therefore, by keeping the content of the impurities Fe, Cu, Zn, Mn, and Si within the above ranges, the anodic oxide coating 34 can be smoothly formed on the positive electrode terminal 3.

[0040] The average distance between the anodic oxide coating 34 on the positive terminal 3 and the edge 221 of the opening 220 in the housing 2 is greater than 0 μm and equal to or less than 30 μm.

[0041] An adhesive layer 35 is provided between the anodic oxide coating 34 and the edge 221 of the opening 220. Therefore, when the average distance is greater than 0 μm and equal to or less than 30 μm, it is possible to suppress the volatilization of the electrolyte from the inside of the casing to the outside, and also to suppress the penetration of liquid from the outside of the casing to the inside, thereby extending the life of the battery 100.

[0042] Furthermore, when the thickness of the adhesive layer 35 is measured at multiple locations, there will be locations where the adhesive layer 35 is absent and the anodic oxide coating 34 abuts against the edge 221 of the opening 220, and at those locations, the distance between the anodic oxide coating 34 and the edge 221 of the opening 220 will be 0 μm. However, even in this case, the adhesive layer 35 is provided at other locations, so the average thickness of the adhesive layer 35 at multiple locations will not be 0 μm. Therefore, the average distance will be greater than 0 μm. Furthermore, an average distance greater than 30 μm is undesirable because it would increase the size of the battery 100.

[0043] The housing 2 includes a material such as Fe, Ni, stainless steel, Cu, or any of these materials plated with Ni.

[0044] This increases the strength of the housing 2, allowing the thickness of the housing 2 to be reduced, thereby enabling the size of the battery 100 to be reduced. Furthermore, while keeping the external size of the housing 2 the same, the internal space of the housing 2 can be increased, and the battery element 1 can be made larger, thereby increasing the battery capacity.

[0045] The anodic oxide coating 34 has a Vickers hardness of HV300 or more.

[0046] The greater the Vickers hardness of the anodic oxide coating 34, the greater the strength of the anodic oxide coating 34. Therefore, the anodic oxide coating 34 is less likely to be damaged when force is applied to the anodic oxide coating 34, for example, during assembly of the battery 100, thereby improving the yield of the battery 100. Furthermore, even if the battery 100 receives an external impact during use, the anodic oxide coating 34 will not be damaged, and short circuits in the battery 100 can be avoided.

[0047] The Vickers hardness of the hard anodized aluminum layer is, for example, HV 400, and the Vickers hardness of the standard anodic oxide coating 34 is, for example, HV 200. Therefore, the anodic oxide coating 34 is preferably, for example, a hard anodized aluminum layer.

[0048] The adhesive layer 35 contains a polyolefin resin.

[0049] The polyolefin resin adhesive layer 35 is less susceptible to deterioration by the electrolyte, even when used in a non-aqueous solvent battery such as a lithium ion secondary battery, and can prevent leakage of the electrolyte over a long period of time. Furthermore, when an abnormality occurs in the lithium ion secondary battery, the adhesive layer 35 softens and peels off, thereby suppressing an increase in internal pressure and minimizing the impact of the abnormality in the battery 100 on the surrounding area.

[0050] [Second embodiment] Next, a battery according to a second embodiment will be described. Fig. 5 is a schematic diagram showing a cross section of the battery according to the second embodiment. Fig. 6 is a schematic diagram showing an enlarged portion of Fig. 5. The battery 100A includes a battery body 1A, a casing 2A, and a positive electrode terminal 3A.

[0051] 5, the battery body 1A includes a positive electrode 11, a negative electrode 12, and a separator 13. In the battery body 1, the positive electrode 11, the separator 13, and the negative electrode 12 are arranged in this order in the vertical direction.

[0052] As shown in FIG. 5, the housing 2A has a housing body 21A and a lid 22A, and houses the battery element 1A. The housing 2A can be made of a material such as stainless steel. The housing body 21A has a bottom 212A and a side 211A. The housing body 21A has a U-shaped cross section and is open at the top. A lid 22A is joined to the upper end of the side 211A. An opening 220A is provided in the side 211A, and the positive terminal 3A is disposed outside the housing 2A and joined to the side 211A while covering the opening 220A of the side 211A. In this way, the opening 220A is sealed by the positive terminal 3A.

[0053] 5 and 6, the positive electrode terminal 3A includes a main body 31A, a protrusion 32A, and an anodized coating 34. The positive electrode terminal 3A has a T-shaped cross section. The main body 31A and the protrusion 32A are made of aluminum or an aluminum alloy.

[0054] The main body 31A extends in the vertical direction. The main body 31A has an upper surface 311A, a lower surface 312A, a front surface 313A, and a rear surface 314A. The upper surface 311A ​​and the lower surface 312A extend substantially parallel to each other. The front surface 313A and the rear surface 314A extend substantially parallel to each other. The protrusion 32A protrudes laterally from the vertical center of the main body 31A. The protrusion 32A has an upper surface 321A, a lower surface 322A, and a front surface 323A. The upper surface 321A and the lower surface 322A extend substantially parallel to each other. The protrusion 32A is inserted into the opening 220A.

[0055] The anodic oxide coating 34 is provided on the main body 31A and the protrusions 32A. Specifically, the anodic oxide coating 34 is provided on the upper surface 311A, the lower surface 312A, and the front surface 313A of the main body 31A, and on the upper surfaces 321A and the lower surfaces 322A of the protrusions 32A. In the second embodiment, the front surface 323A of the protrusions 32A is a region 39A where the anodic oxide coating 34 is not formed. The edge 221A of the opening 220A refers to the region from the inner wall 222A of the side portion 211A to the portion corresponding to the upper surface 311A ​​of the positive terminal 3A, and the region from the inner wall 222A of the side portion 211A to the portion corresponding to the lower surface 312A of the positive terminal 3A. The end 112 of the wiring 111 is connected to the front surface 323A of the protrusions 32A, which is the region where the anodic oxide coating 34 is not formed.

[0056] Furthermore, front surface 313A of main body 31A is joined to side portion 211A via adhesive layer 35. Specifically, front surface 313A of main body 31A is joined to edge portion 221A of opening 220A via adhesive layer 35. Adhesive layer 35 contains epoxy resin.

[0057] As described above, in the battery 100A according to the second embodiment, as in the battery 100 according to the first embodiment, the anodized coating 34 is formed on the positive electrode terminal 3A at a portion facing the adhesive layer 35. Therefore, the thickness of the adhesive layer 35 can be made thinner than when the positive electrode terminal 3A does not have the anodized coating 34, thereby enabling the battery 100A to be made more compact.

[0058] The average distance between the anodic oxide coating 34 on the positive terminal 3A and the edge 221A of the opening 220A in the housing 2A is greater than 0 μm and equal to or less than 30 μm.

[0059] In this way, when the average distance is greater than 0 μm and less than or equal to 30 μm, it is possible to suppress the volatilization of the electrolyte from the inside of the casing to the outside, and also to suppress the penetration of liquid from the outside of the casing into the inside, thereby extending the life of the battery 100A.

[0060] The adhesive layer 35 includes an epoxy resin.

[0061] The adhesive layer 35 containing epoxy resin can withstand high temperatures and effectively suppresses the volatilization of the electrolyte, thereby enabling the battery 100A to have a long life.

[0062] The battery 100 according to the first embodiment and the battery 100A according to the second embodiment can be, for example, a monopolar lithium-ion battery, which makes it possible to supply the high battery capacity density required for electronic devices such as mobile devices, wearable devices, and IoT devices at an optimal voltage of 3 V or more and 4 V or less for electronic devices.

[0063] [First Modification] Next, a first modified example will be described. Fig. 7 is a cross-sectional view showing a positive terminal according to the first modified example. In the positive terminal 3B according to the first modified example, the anodic oxide coating 34 is provided only on the front surface 313A of the main body 31A.

[0064] According to this, the anodic oxide coating 34 is formed only in the portion of the positive electrode terminal 3B where it is most needed, thereby reducing manufacturing costs.

[0065] [Second Modification] Next, a second modified example will be described. Fig. 8 is a cross-sectional view showing a positive electrode terminal according to the second modified example. In a positive electrode terminal 3C according to the second modified example, an anodic oxide coating 34 is provided on a front surface 313A of a main body 31A and on an upper surface 321A and a lower surface 322A of a protrusion 32A.

[0066] This allows the protrusion 32A of the positive electrode terminal 3A to be disposed close to the inner wall 222A of the side portion 211A, thereby making the opening 220A smaller and further improving the sealing performance of the opening 220A.

[0067] [Example] Next, the present invention will be specifically verified through examples.

[0068] [Example 1] Example 1 corresponds to the first embodiment.

[0069] (Creating the battery element) A positive electrode was fabricated by coating a layer of positive electrode active material containing lithium cobalt oxide as the positive electrode active material on an aluminum foil as a positive electrode current collector. A negative electrode was fabricated by coating a layer of negative electrode active material containing a carbon material as the negative electrode active material on a copper foil as a negative electrode current collector. The positive and negative electrodes were wound with a polyethylene microporous membrane separator in between to fabricate a battery element. The electrolyte used was a 1M LiPF6 solution in a 3 / 7 EC / DMC solvent.

[0070] (Preparation of positive terminal) In Example 1, a positive electrode terminal was first produced. Specifically, a clad material was produced by joining an aluminum material (A1050 material), a stainless steel material, and a nickel material. The clad material had a thickness of 250 μm. Next, a disk with a diameter of 9 mm was punched out of this clad material using a press. After this, a hard anodized aluminum layer with an average thickness of 10 μm was formed on the surface of the aluminum material in the clad material disk. To form the hard anodized aluminum layer, an oxalic acid anodized aluminum bath, which is a type of hard anodized aluminum, was used. The hard anodized aluminum layer was formed on a circular portion of the surface of the aluminum material, excluding a circular portion with a diameter of 4 mm in the center. The average thickness of the hard anodized aluminum layer was measured at four points on the hard anodized aluminum layer and the average value of the measured thicknesses.

[0071] (Making the lid) Next, a lid was fabricated. Specifically, a 12 mm diameter disk was punched out of stainless steel (SUS316L: 17Cr-12Ni-2Mo-low C) using a press, and a 6 mm diameter circular hole was formed in the center of this disk. This resulted in a ring-shaped lid.

[0072] The positive electrode terminal and the lid were then joined together with the center of the positive electrode terminal aligned with the center of the lid. Specifically, a polypropylene (PP) adhesive layer was provided on the hard anodized aluminum layer of the positive electrode terminal. This adhesive layer was brought into contact with the lid, and the positive electrode terminal, lid, and adhesive layer were heated to thermally weld the positive electrode terminal and the lid together via the polypropylene adhesive layer. The average thickness of the adhesive layer after thermal welding was 30 μm.

[0073] (Creating Battery A) Next, a housing body was fabricated. Specifically, a housing body with a diameter of 12 mm and a height of 5 mm was formed from stainless steel (SUS316L) by press drawing. The housing body has a bottom and a side, similar to the first embodiment.

[0074] The negative electrode tab of the battery element was then welded to the bottom of the housing body, and the battery element was housed in the housing body. The radial center of the aluminum material of the positive terminal was a non-formation area where the hard anodized aluminum layer was not formed. The positive electrode tab of the battery element was welded to the aluminum surface of this non-formation area.

[0075] Furthermore, after dropping an electrolyte onto the battery element, the lid was joined to the housing body by welding, and the upper opening of the housing body was sealed with the lid, thereby producing a battery A according to Example 1.

[0076] (Creating Battery B) Furthermore, a battery B was produced as a comparative example for the battery A of Example 1. Battery B differs from battery A in that it does not have a hard anodized aluminum layer and that the thickness of the polypropylene adhesive layer is 80 μm.

[0077] (Capacity retention rate test) Battery A was left in an environment with a temperature of 65°C and humidity of 90% for two months. After this period, the capacity retention rate of Battery A was measured and found to be a high rate of 83% on average. The average of 83% is the average value of the capacity retention rates of nine Battery A units.

[0078] In contrast, when Battery B was left in an environment with a temperature of 65°C and humidity of 90% for two months, the average capacity retention rate of Battery B was 41%. The average of 41% is the average value obtained by averaging the capacity retention rates of nine Battery Bs.

[0079] (Consideration) It was found that Battery A had a higher capacity retention rate than Battery B. This is thought to be because Battery A has a hard anodized aluminum layer and a thinner adhesive layer than Battery B, which prevents the electrolyte from volatilizing outside the casing and moisture from penetrating into the casing. It was also confirmed that Battery A did not suffer from short-circuiting even when the adhesive layer was thinner than Battery B.

[0080] The above results mean that in real-world environments, for example in wearable devices such as earphones, the risk of significant capacity degradation occurring before the expected lifespan is reduced.

[0081] [Example 2] Example 2 corresponds to the first embodiment.

[0082] (Creating the battery element) A positive electrode was fabricated by coating a layer of positive electrode active material containing lithium iron phosphate as the positive electrode active material on an aluminum foil as a positive electrode current collector. A negative electrode was fabricated by coating a layer of negative electrode active material containing a carbon material as the negative electrode active material on a copper foil as a negative electrode current collector. The positive and negative electrodes were wound with a polyethylene microporous membrane separator in between to fabricate a battery element. The electrolyte used was a 1M solution of lithium bis(fluorosulfonyl)imide (LiFSI) in a solvent of EC / DMC = 3 / 7.

[0083] (Preparation of positive terminal) In Example 2, a positive electrode terminal was first produced. Specifically, a clad material was produced by joining an aluminum material (A1050 material), a stainless steel material, and a nickel material. The clad material had a thickness of 250 μm. Next, a disk with a diameter of 9 mm was punched out of this clad material using a press. After this, a hard anodized aluminum layer with an average thickness of 20 μm was formed on the surface of the aluminum material in the clad material disk. To form the hard anodized aluminum layer, an oxalic acid anodized aluminum bath, which is a type of hard anodized aluminum, was used. The hard anodized aluminum layer was formed on a circular portion of the surface of the aluminum material, excluding a circular portion with a diameter of 4 mm in the center. The average thickness of the hard anodized aluminum layer was measured at four points on the hard anodized aluminum layer and the average value of the measured thicknesses.

[0084] (Making the lid) Next, a lid was fabricated. Specifically, a 12 mm diameter disk was punched out of stainless steel (SUS316L) using a press, and a 6 mm diameter circular hole was formed in the center of this disk. This resulted in a ring-shaped lid.

[0085] The positive electrode terminal and the lid were then joined together with the center of the positive electrode terminal aligned with the center of the lid. Specifically, an epoxy resin adhesive layer was provided on the hard anodized aluminum layer of the positive electrode terminal. This adhesive layer was brought into contact with the lid, and the positive electrode terminal, lid, and adhesive layer were heated to join the positive electrode terminal and the lid via the epoxy resin adhesive layer. The thickness of the adhesive layer after joining was 0 to 8 μm.

[0086] (Creating Battery C) Next, a housing body was fabricated. Specifically, a housing body with a diameter of 12 mm and a height of 5 mm was formed from stainless steel (SUS316L) by press drawing. The housing body has a bottom and a side, similar to the first embodiment.

[0087] The negative electrode tab of the battery element was then welded to the bottom of the housing body, and the battery element was housed in the housing body. The radial center of the aluminum material of the positive terminal was a non-formation area where the hard anodized aluminum layer was not formed. The positive electrode tab of the battery element was welded to the aluminum surface of this non-formation area.

[0088] Furthermore, after dropping an electrolyte onto the battery element, the lid was joined to the housing body by welding, and the upper opening of the housing body was sealed with the lid, thereby producing a battery C according to Example 2.

[0089] (Creating Battery D) Furthermore, Battery D was produced as a comparative example for Battery C of Example 2. Battery D differs from Battery C in that it does not have a hard anodized aluminum layer and that the thickness of the epoxy resin adhesive layer is 80 μm.

[0090] (Capacity retention rate test) Battery C was left in an environment with a temperature of 85°C and humidity of 90% for one month. After this, the capacity retention rate of Battery C was checked and found to be a high rate of 96% on average. The average of 96% is the average value of the capacity retention rates of nine Battery Cs.

[0091] In contrast, when Battery D was left in an environment with a temperature of 85°C and humidity of 90% for one month, the average capacity retention rate of Battery D was 28%. The average of 28% is the average value obtained by averaging the capacity retention rates of nine Battery Ds.

[0092] (Consideration) It was found that Battery C had a higher capacity retention rate than Battery D. This is thought to be because Battery C has a hard anodized aluminum layer and a thinner adhesive layer than Battery D, which prevents the electrolyte from volatilizing outside the casing and water from penetrating into the casing. It was also confirmed that Battery C did not suffer from short-circuiting even when the adhesive layer was thinner than Battery D.

[0093] [Example 3] Example 3 corresponds to the second embodiment.

[0094] (Creating the battery element) A positive electrode was fabricated by coating a layer of positive electrode active material containing lithium cobalt oxide as the positive electrode active material on an aluminum foil as a positive electrode current collector. A negative electrode was fabricated by coating a layer of negative electrode active material containing a carbon material as the negative electrode active material on a copper foil as a negative electrode current collector. The positive and negative electrodes were wound with a polyethylene microporous membrane separator in between to fabricate a battery element. The electrolyte used was a 1M LiPF6 solution in a 3 / 7 EC / DMC solvent.

[0095] (Preparation of positive terminal) The positive electrode terminal of Example 3 had the same shape as that of the second embodiment. The material of the positive electrode terminal was aluminum (A5052 material). As in the second embodiment, a hard anodized aluminum layer with an average thickness of 30 μm was formed on the upper, lower, and front surfaces of the main body of the positive electrode terminal and on the upper and lower surfaces of the protrusions. An oxalic acid anodized aluminum bath, which is a type of hard anodized aluminum, was used to form the hard anodized aluminum layer. The average thickness of the hard anodized aluminum layer was determined by measuring the thickness of the hard anodized aluminum layer at four locations and averaging the measured thicknesses.

[0096] (Housing) The housing has a housing body and a lid, and houses the battery element, as in the second embodiment. The housing is made of stainless steel.

[0097] (Creating Battery E) An epoxy resin adhesive layer was provided on the hard anodized aluminum layer formed on the front surface of the body of the positive terminal. The protrusion of the positive terminal was inserted into the opening of the housing body, and the body of the positive terminal was joined to the edge of the opening via the adhesive layer. The battery body was housed inside the housing body, and the positive electrode tab of the battery body was welded to the front surface of the protrusion of the positive electrode terminal. The negative electrode tab was welded to the bottom of the housing body. Then, the lid was joined to the housing body by seam welding to produce Battery E.

[0098] (Creating Battery F) In addition, Battery F was produced as a comparative example to Battery E of Example 3. Battery F is the secondary battery of Patent Document 1. As described above, Battery F is provided with a rivet that serves as a positive terminal. The rivet has a plate portion and a pin protruding from the plate portion. After the pin is inserted into the through-hole of the gasket, the tip of the pin is crushed and deformed to crimp the rivet to the gasket. The rivet, gasket, and battery element are housed inside a housing.

[0099] (Capacity retention rate test) Battery E was left in an environment with a temperature of 70°C and a humidity of 95% for two months. After this, the capacity retention rate of Battery E was checked and found to be high, at an average of 90% or more. Note that the average of 90% or more is the average value of the capacity retention rates of nine Battery E.

[0100] In contrast, when Battery F was left in an environment of 70°C and 95% humidity for two months, the capacity retention rate of Battery F was equivalent to that of Battery E.

[0101] (Battery capacity test) Furthermore, unlike battery E of Example 3, the rivets, gasket, and battery element of battery F are housed inside the housing. In contrast, the electronic element of Example 3 is disposed outside the housing. Therefore, the electronic element of battery E of Example 3 is larger than the battery element of battery F according to Patent Document 1, and the battery capacity of battery E of Example 3 is 7% larger than the battery capacity of battery F according to Patent Document 1. [Explanation of symbols]

[0102] 1. 1A battery element 11 Positive electrode 111 Wiring 112 End 113 End 12 Negative electrode 121 Wiring 13 Separator 100, 100A battery 2, 2A housing 21, 21A housing body 211, 211A Side 212, 212A Bottom 213 Upper End 22, 22A Lid 220, 220A Opening 221, 221A Edge 222, 222A Inner Wall 223 Outer Peripheral End 224 Surface 225 Back Surface 3 Positive Electrode Terminal 31 Nickel Material 32 Stainless Steel Material 33 Aluminum Material 34 Anodic Oxide Film 341 Inner Peripheral End 342 Outer Peripheral End 35 Adhesive Layer 351 End 352 End 37 First Part 38 Forming Region 39 Non-Forming Region 3A Positive Electrode Terminal 31A Body Part 311A Upper Surface 312A Lower Surface 32A Protrusion 321A Upper Surface 322A Lower Surface 39A Non-Forming Region

Claims

1. a battery body including a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode; a housing that houses the battery body and has an opening; a positive terminal that covers the opening and is disposed outside the housing; an adhesive layer that joins the housing and the positive electrode terminal, a surface of the positive terminal facing the housing includes a formation region where an insulating anodic oxide coating is provided and a non-formation region where the anodic oxide coating is not provided, the forming region is bonded to the housing via the adhesive layer; The non-forming region is electrically connected to a wiring connected to the positive electrode. battery.

2. The positive electrode terminal has an anodized coating on a side surface thereof. The battery of claim 1 .

3. The positive electrode terminal has a protrusion, and the protrusion and the positive electrode are electrically connected to each other. The battery of claim 1 .

4. An anodized coating is formed on a portion where the housing and the positive electrode terminal face each other. The battery of claim 1 .

5. The thickness of the anodic oxide coating is 2 μm or more and 100 μm or less. The battery of claim 1 .

6. The thickness of the anodic oxide coating is 10 μm or more and 50 μm or less. The battery of claim 5.

7. The positive electrode terminal includes at least one of aluminum, an aluminum alloy, and a clad material containing aluminum. The battery of any one of claims 1 to 6.

8. The positive electrode terminal is Contains 93% by mass or more of Al, The battery of any one of claims 1 to 6.

9. The positive electrode terminal is Contains 93 mass% or more of Al and at least one of Fe, Cu, Zn, and Mn; The battery of any one of claims 1 to 6.

10. The positive electrode terminal is Contains less than 2% by mass of Si; 10. The battery of claim 9.

11. The thickness of the adhesive layer is 5 um or more and 200 um or less. The battery of any one of claims 1 to 6.

12. an average distance between the casing facing the anodic oxide coating on the positive terminal and the anodic oxide coating is greater than 0 μm and less than or equal to 30 μm; The battery of any one of claims 1 to 6.

13. The anodic oxide coating is anodized aluminum. The battery of any one of claims 1 to 6.

14. The housing includes: Fe, Ni, stainless steel, Cu, or materials obtained by plating these with Ni, The battery of any one of claims 1 to 6.

15. The anodized coating has a Vickers hardness of HV300 or more. The battery of any one of claims 1 to 6.

16. The adhesive layer contains a polyolefin resin. The battery of any one of claims 1 to 6.

17. The adhesive layer comprises an epoxy resin. The battery of any one of claims 1 to 6.

18. The battery according to claim 1 , wherein the positive electrode and the positive electrode terminal are connected via a positive electrode tab.

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