Battery

Abstract

The present technology relates to a battery having: a housing member; a terminal member connected to the power generation element; and a resin member that insulates and seals between the housing member and the terminal member, in which a through-hole through which the terminal member passes is formed in the housing member, the resin member including: an inner side portion that is in contact with an inner surface of the housing member; a hole interior filled between a wall surface of the through hole and the terminal member; and an outer part which is in contact with the outer surface of the housing member, has a smaller volume than the inner part, and satisfies either a first condition in which the thermal expansion coefficient of the housing member is greater than the thermal expansion coefficient of the inner part and the tensile strength of the inner part is lower than the tensile strength of the outer part, or a second condition in which the thermal expansion coefficient of the outer part is greater than the thermal expansion coefficient of the inner part. The second condition is that the thermal expansion coefficient of the housing member is smaller than the thermal expansion coefficient of the inner portion, and the tensile strength of the outer portion is lower than the tensile strength of the inner portion.

Description

Technical Field

[0001] The disclosed technology relates to batteries. Background Art

[0002] In the battery described in Patent Document 1, a current collector terminal is disposed through the outer casing. The current collector terminal is connected to the electrode body. A terminal mounting hole for the current collector terminal is formed in the outer casing. An insulating material is embedded between the terminal mounting hole and the current collector terminal. The insulating material is integrally molded with the outer casing and the current collector terminal.

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2021-86813

[0004] The above-mentioned conventional technology has the problem of poor durability against thermal cycling of the battery. This is due to the close contact of components with different thermal expansion coefficients, such as metal (casing member, current collecting terminal) and resin (insulating material). Summary of the Invention

[0005] An object of the disclosed technology is to provide a battery having excellent durability against thermal cycles.

[0006] A battery in one technical solution of the presently disclosed technology comprises: a shell component with a built-in power generation element; a terminal component connected to the power generation element and arranged to pass through the shell component; and a resin component for insulating and sealing the shell component and a through hole for the terminal component to pass through is formed in the shell component, the resin component including: an inner portion in contact with the inner surface of the shell component; an interior of the hole filling the space between the wall of the through hole and the terminal component; and an outer portion in contact with the outer surface of the shell component and having a volume smaller than the inner portion, satisfying either the first condition or the second condition, the first condition being that the thermal expansion coefficient of the shell component is greater than the thermal expansion coefficient of the inner portion, and the tensile strength of the inner portion is lower than the tensile strength of the outer portion, and the second condition being that the thermal expansion coefficient of the shell component is smaller than the thermal expansion coefficient of the inner portion, and the tensile strength of the outer portion is lower than the tensile strength of the inner portion.

[0007] In the battery of the above technical solution, the portion of the outer shell member provided with the terminal member and the resin member attempts to bend due to temperature changes. Under the first condition, the portion attempts to bend inward when cold and outward when heated. Under the second condition, on the contrary, the portion attempts to bend outward when cold and inward when heated. However, the portion of the resin member that becomes the elongated side when cold (the inner portion under the first condition and the outer portion under the second condition) has a low tensile strength and is therefore not easily broken when cold.

[0008] Preferably, in the battery according to the above technical solution, the resin component includes a filler, and when the first condition is satisfied, the filler content in the inner portion is lower than the filler content in the outer portion, and when the second condition is satisfied, the filler content in the inner portion is higher than the filler content in the outer portion. Alternatively, preferably, the resin component includes an elastomer, and when the first condition is satisfied, the elastomer content in the inner portion is higher than the elastomer content in the outer portion, and when the second condition is satisfied, the elastomer content in the inner portion is lower than the elastomer content in the outer portion. In this way, the relationship between the tensile strengths in the inner portion and the outer portion can be satisfied. In addition, it is preferred that the base resin of the inner portion and the base resin of the outer portion are the same type of resin.

[0009] Preferably, in the battery according to any of the above technical solutions, a roughened surface region, where the metal and resin intersect, is provided in at least a portion of the area of the outer shell member's surface covered by the resin component and the area of the terminal member's surface covered by the resin component. The anchoring structure formed by the roughened surface region helps improve the adhesion between the outer shell member and the resin component, and between the terminal member and the resin component. Furthermore, in this technical solution, since either the first or second condition is satisfied, cracking is less likely to occur.

[0010] According to the disclosed technology, a battery having excellent durability against thermal cycles is provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a perspective view of a battery according to an embodiment.

[0012] Figure 2 This is the front view of the terminal part.

[0013] Figure 3 It is a side view of the terminal part.

[0014] Figure 4 This is a perspective view of the terminal component.

[0015] Figure 5 It is a cross-sectional view of the terminal portion.

[0016] Figure 6 Only shows Figure 5 Cross-sectional view of the resin part in FIG.

[0017] Description of Reference Numerals

[0018] 1…battery; 2…housing component; 3…generating element; 4…housing; 5…cover; 8…terminal surface; 9…terminal component; 10…terminal component; 11…resin component; 12…connecting portion; 13…middle portion; 14…through hole; 16…inner portion; 17…inside of the hole; 18…outer portion; 21…thick line; 22…roughened surface area; 24…external portion. DETAILED DESCRIPTION

[0019] exist Figure 1 1 shows a battery 1 according to an embodiment embodying the disclosed technology. Battery 1 incorporates a power generation element 3 within a housing 2. Housing 2 comprises a case 4 and a lid 5. Case 4 is a box-shaped component housing power generation element 3 and has an opening at the top. Lid 5 is a plate-shaped component that closes the opening of case 4. Both case 4 and lid 5 are part of housing 2. Power generation element 3 is an electrode assembly comprising positive and negative electrode plates and an electrolyte.

[0020] Positive and negative terminal portions 6 and 7 are provided near both ends of the longitudinal direction of the cover 5. Terminal surfaces 8 are exposed at both terminals 6 and 7. Terminal surfaces 8 are part of the surface of terminal members 9 and 10, which will be described later. Resin member 11 insulates terminal members 9 and 10 from the cover 5. Resin member 11 also seals the gaps between terminal member 9 and the cover 5, and between terminal member 10 and the cover 5.

[0021] The terminal member 9 will be described. Figures 2 to 4 1 and 2 show the terminal member 9 in a separate state. Figure 2 Therefore Figure 3 The main view of the terminal component 9 is observed along the line of sight of arrow A. Figure 3 Therefore Figure 2 The side view of the terminal part 9 is observed along the line of sight of arrow B. Figure 3 In FIG, in addition to the terminal member 9, a part of the power generating element 3 is shown by a dotted line. Figure 4 It is from Figure 2 、 Figure 3 A perspective view of the terminal member 9 as viewed from the direction of arrow C in FIG. The terminal member 9 is a conductive member connected to the power generation element 3 inside the outer shell member 2 . The terminal member 9 is a member provided so as to penetrate the lid 5 .

[0022] The terminal member 9 includes an external portion 24, a connecting portion 12, and an intermediate portion 13. The external portion 24 is a portion for connection to an external conductor. Figure 1 The terminal surface 8 shown is the surface facing outward in the external portion 24. The connecting portion 12 is a portion connected to one electrode plate of the power generation element 3. The intermediate portion 13 is a portion connecting the external portion 24 and the connecting portion 12.

[0023] Terminal member 10 is a conductive member having a shape that is a left-right inversion of terminal member 9. Terminal members 9 and 10 are generally made of different types of metal. For example, of terminal members 9 and 10, aluminum is used as the positive electrode terminal member, and copper is used as the negative electrode terminal member.

[0024] The terminal portion 6 will be described. Figure 5 It is a cross-sectional view of the terminal portion 6 in the cover 5 . Figure 5 The figure shown is the same as that in Figure 1 The longitudinal sections of the cover 5 shown by arrows D and D are parallel to each other. Figure 5 The longitudinal section is a section at a position near the center in the width direction of the cover body 5. Figure 5 As shown, a through hole 14 is formed in the cover 5. The through hole 14 is shaped to allow the terminal member 9 to pass therethrough.

[0025] The cover body 5 does not contact the terminal part 9. The above-mentioned resin part 11 is provided between the cover body 5 and the terminal part 9. The presence of the resin part 11 prevents the cover body 5 from contacting the terminal part 9. The resin part 11 also fills the through hole 14. The internal space of the housing part 2 is separated from the external space by the resin part 11. The resin part 11 is molded in a state where the terminal part 9 is positioned relative to the cover body 5. The cover body 5 and the terminal part 9 are integrated by the resin part 11. In this form, the terminal surface 8 and the outer surface 15 of the resin part 11 are almost coplanar.

[0026] like Figure 6 As shown, the resin component 11 includes an inner portion 16, a hole inner portion 17 and an outer portion 18. The inner portion 16 is the inner portion of the resin component 11. Figure 5 The portion of the hole 17 that is located below the cover 5. Figure 5 The portion within the thickness range of the cover 5. Similarly, the outer portion 18 is a portion located above the cover 5. In other words, the inner portion 16 is a portion in contact with the inner surface 19 of the cover 5. The inside of the hole 17 is a portion between the wall of the filling through hole 14 and the terminal component 9. The outer portion 18 is a portion in contact with the outer surface 20 of the cover 5. For the sake of convenience, Figure 6 Only the resin part 11 is shown. In fact, Figure 6 The resin member 11 having the shape shown does not exist as a separate component.

[0027] Comparing the volumes of inner portion 16 and outer portion 18, outer portion 18 has a smaller volume. This is because the connection between battery 1 and the external circuit prevents outer portion 18 and terminal surface 8 from protruding too far from outer surface 20. This means that the expansion and contraction of resin member 11 relative to lid 5 under temperature fluctuations is primarily determined by the larger volume of inner portion 16 compared to outer portion 18.

[0028] In battery 1, a special relationship is satisfied between the magnitude relationship of the thermal expansion coefficient between cover 5 and inner portion 16, and the magnitude relationship of the tensile strength between inner portion 16 and outer portion 18. This special relationship includes two conditions: a first condition and a second condition, and either condition can be satisfied.

[0029] The contents of the first and second conditions are as follows.

[0030] First condition: the thermal expansion coefficient of the cover 5 is greater than the thermal expansion coefficient of the inner portion 16 , and the tensile strength of the inner portion 16 is lower than the tensile strength of the outer portion 18 .

[0031] Second condition: the thermal expansion coefficient of the cover 5 is smaller than the thermal expansion coefficient of the inner portion 16 , and the tensile strength of the outer portion 18 is lower than the tensile strength of the inner portion 16 .

[0032] The first condition will be described. Under the first condition, based on the above-mentioned relationship between the magnitudes of the thermal expansion coefficients, the expansion and contraction of the cover 5 relative to temperature changes is more significant than the expansion and contraction of the inner portion 16. Therefore, Figure 5 The cover 5 shown attempts to flex by convexing downward when cold and convexing upward when warm.

[0033] If we focus on the cold, the inner portion 16 will also bend downward in the cold. This is because the upper surface of the inner portion 16 is dragged by the contraction of the cover 5, and thus contracts more strongly than the original contraction. On the other hand, tensile stress is applied to the lower surface of the inner portion 16, which becomes the elongated side. This tensile stress is an important factor that causes the inner portion 16 to rupture, peel off from the terminal part 9, and peel off from the cover 5. However, under the first condition, the softness of the inner portion 16 is high, so even in the cold, it will not actually rupture or peel off.

[0034] During heating, outer portion 18, on the other hand, becomes stretched, exerting tensile stress on its upper surface. However, during heating, the resin softens to a certain extent due to the high temperature. Therefore, outer portion 18 also maintains a certain degree of flexibility, preventing cracking or the like from occurring during heating.

[0035] The second condition will be explained. Under the second condition, due to the aforementioned relationship between the coefficients of thermal expansion, the expansion and contraction of the inner portion 16 relative to temperature changes is more pronounced than that of the cover 5. Therefore, the cover 5 attempts to bend in the opposite direction to the first condition, convexing upward when cold and convexing downward when warm.

[0036] If we focus on cold weather, the outer portion 18 will also bend upward in a convex manner. This is because the lower surface of the outer portion 18 is dragged by the contraction of the cover 5, causing it to contract more strongly than it would otherwise. On the other hand, tensile stress is applied to the upper surface of the outer portion 18. This tensile stress is a major factor in causing the outer portion 18 to crack or peel. However, under the second condition, the outer portion 18 is more flexible, so even in cold weather, it will not actually crack or peel.

[0037] During heating, tensile stress is applied to the lower surface of the inner portion 16. However, during heating, the temperature is high, so the resin of the inner portion 16 also softens to a certain extent. Therefore, cracks, etc., do not occur in the inner portion 16 during heating.

[0038] As described above, in the battery 1 of this embodiment, by satisfying either the first or second condition, cracking and peeling in the resin member 11 are suppressed, both in cold and warm conditions. Consequently, the battery 1 has excellent durability against thermal cycles.

[0039] As described above, in the resin component 11 of this embodiment, the inner portion 16 and the outer portion 18 have different properties and states. At least the tensile strength of the inner portion 16 and the outer portion 18 differs. The thermal expansion coefficient may also differ between the inner portion 16 and the outer portion 18. There are three methods for imparting such different properties and states to the inner portion 16 and the outer portion 18.

[0040] A method of using a composite resin containing a filler as the resin member 11 and varying the filler blending ratio

[0041] A method of using a composite resin containing an elastomer as the resin member 11 and varying the elastomer blending ratio

[0042] Methods of using different types of base resins

[0043] The following describes the method of using fillers. Fillers are tiny solid substances. For example, glass fibers, glass powder, etc. can be used as fillers. Given the same base resin, the higher the filler ratio, the higher the tensile strength of the composite resin. Therefore, under the first condition, the filler ratio in the outer portion 18 is higher than that in the inner portion 16, while under the second condition, the filler ratio in the inner portion 16 is higher than that in the outer portion 18.

[0044] If the base resin is the same, the higher the filler ratio, the lower the thermal expansion coefficient of the composite resin. If the base resin of the resin member 11 is, for example, PPS resin, and the material of the cover 5 is, for example, aluminum, the thermal expansion coefficient of the base resin is approximately twice that of the cover 5.

[0045] Under the first condition, the filler ratio in inner portion 16 is increased to a level where the thermal expansion coefficient of the composite resin forming inner portion 16 is lower than that of aluminum. Under the first condition, the filler ratio in outer portion 18 is higher than this. Under the second condition, the filler ratio in inner portion 16 is suppressed to a level where the thermal expansion coefficient of the composite resin forming inner portion 16 is not lower than that of aluminum. Under the second condition, the filler ratio in outer portion 18 is lower than this. In the case of the method using filler, the filler ratio is adjusted as described above to satisfy either the first or second condition.

[0046] The method using an elastomer will be described. Elastomers are polymer materials with a relatively low elastic modulus and exhibit viscoelastic properties. Given the same base resin, the lower the elastomer ratio, the higher the tensile strength of the composite resin. Therefore, under the first condition, the elastomer ratio in the inner portion 16 is higher than that in the outer portion 18. Under the second condition, the elastomer ratio in the outer portion 18 is higher than that in the inner portion 16.

[0047] If the base resin is the same, the lower the mixing ratio of the elastomer, the smaller the thermal expansion coefficient of the composite resin. Under the first condition, the mixing ratio of the elastomer in the inner portion 16 is suppressed to the extent that the thermal expansion coefficient of the composite resin in the inner portion 16 is lower than the thermal expansion coefficient of aluminum. The mixing ratio of the elastomer in the outer portion 18 under the first condition is lower than it. Under the second condition, the mixing ratio of the elastomer in the inner portion 16 is increased to the extent that the thermal expansion coefficient of the composite resin in the inner portion 16 is not lower than the thermal expansion coefficient of aluminum. The mixing ratio of the elastomer in the outer portion 18 under the second condition is higher than it. In the case of the method using an elastomer, the mixing ratio of the elastomer is adjusted as described above, thereby satisfying the first condition or the second condition.

[0048] The following describes a method using different types of base resins. For example, even PPS resins come in various types depending on factors such as molecular weight and the degree of crosslinking. The resin type for the inner portion 16 and the different resin type for the outer portion 18 can be selected to satisfy either the first or second condition.

[0049] Although the hole interior 17 is not mentioned in the above description of the resin member 11, the properties and state of the hole interior 17 may be the same as those of either the inner portion 16 or the outer portion 18. Alternatively, the boundary between the portion having the same properties and state as the inner portion 16 and the portion having the same properties and state as the outer portion 18 may be located in the middle of the hole interior 17.

[0050] In this way, resin component 11, which has two portions of resin with different properties and states, is molded using two base resins. With terminal component 9 positioned and held relative to through-hole 14 of lid 5, base resin for inner portion 16 is supplied from below to form inner portion 16. Alternatively, inner portion 16 and hole interior 17 are formed. Subsequently, base resin for outer portion 18 is supplied from above to form outer portion 18. Alternatively, outer portion 18 and hole interior 17 are formed. When using a composite resin, a filler or elastomer is pre-mixed into the base resin.

[0051] When the base resins of the inner portion 16 and the outer portion 18 are the same type of resin or resins with a high affinity, a mixed layer may form at the contact point between the two resin types depending on the molding conditions. In this case, there is an advantage that separation between the two resin types is less likely to occur during subsequent cooling and heating cycles.

[0052] Next, the anchoring structure of the terminal portion 6 is described. In the terminal portion 6 of the battery 1 of this form, an anchoring structure is provided at the joint surface between the metal component (cover 5 and terminal component 9) and the resin component 11. The anchoring structure is provided within the range covered by the resin component 11 on the surface of the metal component. The anchoring structure is a rough surface area where the metal and the resin enter each other. Figure 5 In FIG. 1 , the portion of the anchor structure that appears in the cross-sectional view is indicated by a thick line 21 .

[0053] In the anchoring structure, the metal part and the resin part 11 are meshed with each other. Therefore, in the anchoring structure, the metal part and the resin part 11 have good adhesion and are not easily peeled off. On the other hand, this is also an important factor that easily causes the resin part 11 to break when the cover 5 attempts to bend, such as when it is cold or warmed up. The part that is prone to breakage is the side of the inner part 16 and the outer part 18 of the resin part 11 where the tensile stress acts. If the anchoring structure is provided, the tensile stress will not be relieved by the peeling of the metal part and the resin part 11, so it is easy to break correspondingly. However, in the resin part 11 of this form, the properties and states of the inner part 16 and the outer part 18 are appropriately set, as in the first or second condition mentioned above. Therefore, even if the anchoring structure is provided, it is not easy for the resin part 11 to break.

[0054] The portions of the cover 5 and terminal member 9 that will become the anchoring structure are roughened in advance. Within the roughened area, minute concave and convex shapes, approximately tens to hundreds of nanometers in size, are formed. During the molding of the resin member 11, the raw resin flows into the recessed portions of these concave and convex shapes, forming the anchoring structure.

[0055] exist Figure 2 and Figure 3 , the range where the roughening treatment is applied in the terminal part 9, i.e., the roughening range 22, is shown. The roughening range 22 is the area from the level of the lower surface 23 facing the outside 24 to the middle of the middle portion 13 in the terminal part 9. The lower surface 23 is also roughened. The terminal surface 8 is not roughened. The lower limit of the roughening range 22 does not need to be strictly specified. Even if the roughening range 22 exceeds the range of contact with the resin part 11 downward, there is no particular problem.

[0056] In the above, the resin component 11 of the terminal portion 6 is described, but the same is true for the resin component 11 of the terminal portion 7. An anchor structure can also be provided in the terminal portion 7. The roughening range of the terminal component 10 used for the anchor structure is also the same as that of the terminal portion 7. Figure 2 and Figure 3 There are no particular differences in the ranges shown.

[0057] As described in detail above, according to this embodiment, the resin member 11 between the cover 5 and the terminal members 9 and 10 extending through the cover 5 is configured to satisfy the first or second condition described above. This prevents cracking of the resin member 11. In particular, even in areas that are prone to cracking, namely those that expand in cold weather, cracking is less likely to occur. This results in a battery 1 that exhibits excellent durability against thermal cycling.

[0058] The present embodiments and examples are merely illustrative and do not in any way limit the disclosed technology. Therefore, the disclosed technology is susceptible to various improvements and modifications without departing from its main purpose. For example, battery 1 can be of any type. It can be a lithium-ion battery, a nickel-metal hydride battery, an all-solid-state battery, or any other type. The disclosed technology can be applied to both or either of the positive and negative terminals 6 and 7 within battery 1.

[0059] The raw resin constituting resin member 11 may also be a composite resin comprising a filler and an elastomer blended into a base resin. The base resin of resin member 11 may also be a resin other than PPS resin. Cover 5 may also be made of a metal other than aluminum. The anchoring structure of terminal members 9, 10 and cover 5 may not be in contact with the resin of resin member 11 throughout its entirety, but rather only a portion.

Claims

1. A battery, wherein: The battery has: Housing components with built-in power generation elements; a terminal member connected to the power generating element and provided to penetrate the housing member; and a resin component for insulating and sealing the housing component and the terminal component; The housing member is formed with a through hole for the terminal member to pass through. The resin component includes: an inner portion in contact with an inner surface of the housing member; The interior of the hole is filled between the wall of the through hole and the terminal component; and The outer portion contacts the outer surface of the housing component and has a smaller volume than the inner portion, The battery satisfies either a first condition or a second condition, wherein the first condition is that the thermal expansion coefficient of the outer shell component is greater than the thermal expansion coefficient of the inner portion, and the tensile strength of the inner portion is lower than the tensile strength of the outer portion, and the second condition is that the thermal expansion coefficient of the outer shell component is less than the thermal expansion coefficient of the inner portion, and the tensile strength of the outer portion is lower than the tensile strength of the inner portion.

2. The battery according to claim 1, wherein The resin component contains a filler, When the first condition is satisfied, the filler content of the inner portion is lower than the filler content of the outer portion. When the second condition is satisfied, the filler content in the inner portion is higher than the filler content in the outer portion.

3. The battery according to claim 1, wherein The resin component includes an elastomer, When the first condition is satisfied, the elastic body content of the inner portion is higher than the elastic body content of the outer portion. When the second condition is satisfied, the elastic body content in the inner portion is lower than the elastic body content in the outer portion.

4. The battery according to claim 2 or 3, wherein The base resin of the inner portion and the base resin of the outer portion are the same type of resin.

5. The battery according to any one of claims 1 to 3, wherein A rough surface region where metal and resin intersect is provided in at least a portion of the surface of the case member covered by the resin member and the surface of the terminal member covered by the resin member.

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