Battery

Abstract

To provide a battery having excellent durability against a cooling cycle.SOLUTION: A battery according to an embodiment of the present disclosure includes: a case member (4 and 5); a terminal member 9 connected to a power generation element; and a resin member 11 that insulates and seals between the case member 5 and the terminal member 9, and a through hole 14 through which the terminal member 9 passes is formed in the case member 5. The resin member 11 includes: an inner part that contacts an inner surface of the case member 5; a hole inner part that fills a space between a wall surface of the through hole 14 and the terminal member 9; and an outer part that contacts an outer surface of the case member 5 and has a smaller volume than the inner part. The battery satisfies one of the following conditions of a first condition in which a thermal expansion coefficient of the case member 5 is larger than the thermal expansion coefficient of the inner part and a tensile strength of the inner part is lower than the tensile strength of the outer part and a second condition in which the thermal expansion coefficient of the case member 5 is smaller than the thermal expansion coefficient of the inner part and the tensile strength of the outer portion is lower than the tensile strength of the inner part.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The disclosed technology relates to batteries.

Background Art

[0002] In the battery described in Patent Document 1, a current collecting terminal is disposed through a case member. The current collecting terminal is connected to an electrode body. A terminal mounting hole through which the current collecting terminal passes is formed in the case member. An insulating material is embedded between the terminal mounting hole and the current collecting terminal. The insulating material is integrally formed with the case member and the current collecting terminal.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The above - mentioned conventional technology had a problem in that the durability against the thermal cycle of the battery was weak. This is because members made of materials with different coefficients of thermal expansion, such as metal (case member, current collecting terminal) and resin (insulating material), are in close contact.

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

Means for Solving the Problems

[0006] A battery in one aspect of the disclosed technology comprises a case member containing a power generation element, a terminal member connected to the power generation element and provided through the case member, and a resin member insulating and sealing the space between the case member and the terminal member. The case member has a through hole through which the terminal member passes. The resin member includes an inner portion in contact with the inner surface of the case member, an interior portion filling the space between the wall of the through hole and the terminal member, and an outer portion in contact with the outer surface of the case member and having a smaller volume than the inner portion. The battery satisfies either a first condition where the thermal expansion coefficient of the case member 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, or a second condition where the thermal expansion coefficient of the case member 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. Furthermore, if the resin component contains a filler, and the first condition is met, the filler content of the inner part is lower than the filler content of the outer part, and if the second condition is met, the filler content of the inner part is lower than the filler content of the outer part. It's an expensive battery. A battery in another aspect of the disclosed technology comprises a case member containing a power generation element, a terminal member connected to the power generation element and provided through the case member, and a resin member insulating and sealing the space between the case member and the terminal member, wherein the case member has a through hole through which the terminal member passes, and the resin member includes an inner part in contact with the inner surface of the case member, a hole interior filling the space between the wall of the through hole and the terminal member, and an outer part in contact with the outer surface of the case member and having a smaller volume than the inner part, satisfying either a first condition in which the coefficient of thermal expansion of the case member is greater than the coefficient of thermal expansion of the inner part and the tensile strength of the inner part is lower than the tensile strength of the outer part, and a second condition in which the coefficient of thermal expansion of the case member is less than the coefficient of thermal expansion of the inner part and the tensile strength of the outer part is lower than the tensile strength of the inner part, and the resin member contains an elastomer, and if the first condition is satisfied, the elastomer content of the inner part is higher than the elastomer content of the outer part, and if the second condition is satisfied, the elastomer content of the inner part is lower than the elastomer content of the outer part.

[0007] In the battery described above, the parts of the case where the terminal member and resin member are located tend to bend with temperature. In the first condition, the parts tend to bend inward when cold and outward when warm. In the second condition, conversely, the parts tend to bend outward when cold and inward when warm. However, the parts of the resin member that tend to stretch in cold (the inner part in the first condition and the outer part in the second condition) have low tensile strength, so they are less likely to crack even in cold temperatures.

[0008] In the above embodiment, the battery , inside It is desirable that the base resin of the side and the base resin of the outer part be of the same type.

[0009] above Recording In this embodiment of the battery, it is desirable that 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 be provided with a rough surface area where the metal and resin are interlocked. The anchor structure provided by the rough surface area contributes to improving the adhesion between the case member and the resin member, and between the terminal member and the resin member. Furthermore, since this embodiment satisfies either the first or second condition, cracking is less likely to occur. [Effects of the Invention]

[0010] According to the disclosed technology, a battery with excellent durability against thermal cycling is provided. [Brief explanation of the drawing]

[0011] [Figure 1] This is a perspective view of a battery according to an embodiment. [Figure 2] This is a front view of the terminal component. [Figure 3] This is a side view of the terminal component. [Figure 4] This is a perspective view of the terminal component. [Figure 5] This is a cross-sectional view of the terminal section. [Figure 6] This is a cross-sectional view showing only the resin component from Figure 5. [Modes for carrying out the invention]

[0012] Figure 1 shows a battery 1 according to an embodiment of the disclosed technology. The battery 1 has a power generation element 3 built into a case member 2. The case member 2 is composed of a box body 4 and a lid body 5. The box body 4 is a box-shaped member that houses the power generation element 3 and has an opening at the top. The lid body 5 is a plate-shaped member that closes the opening of the box body 4. Both the box body 4 and the lid body 5 are parts of the case member 2. The power generation element 3 is an electrode assembly in which positive and negative electrode plates are integrated together with an electrolyte.

[0013] Positive and negative terminal portions 6 and 7 are provided near both ends in the longitudinal direction of the cover 5. Terminal surfaces 8 are exposed at the locations of terminal portions 6 and 7. Terminal surfaces 8 are part of the surfaces of terminal members 9 and 10, which will be described later. Terminal members 9 and 10 are insulated from the cover 5 by a resin member 11. The resin member 11 also serves to seal the space between terminal member 9 and the cover 5, and between terminal member 10 and the cover 5.

[0014] The terminal member 9 will be described. The terminal member 9 in a single state is shown in FIGS. 2 to 4. FIG. 2 is a front view of the terminal member 9 as viewed along the line of sight of arrow A in FIG. 3. FIG. 3 is a side view of the terminal member 9 as viewed along the line of sight of arrow B in FIG. 2. In FIG. 3, in addition to the terminal member 9, a part of the power generation element 3 is shown by a dashed line. FIG. 4 is a perspective view of the terminal member 9 as viewed from the direction of arrow C in FIGS. 2 and 3. The terminal member 9 is a conductive member connected to the power generation element 3 inside the case member 2. The terminal member 9 is a member provided through the lid body 5.

[0015] The terminal member 9 has an external connection part 24, a connection part 12, and an intermediate part 13. The external connection part 24 is a part for connection with an external conductor. The terminal surface 8 shown in FIG. 1 is the outward-facing surface of the external connection part 24. The connection part 12 is a part connected to one electrode plate of the power generation element 3. The intermediate part 13 is a part connecting the external connection part 24 and the connection part 12.

[0016] The terminal member 10 is a conductive member having a shape obtained by reversing the terminal member 9 left and right. The terminal member 9 and the terminal member 10 are generally made of different kinds of metals. For example, among the terminal members 9 and 10, aluminum is used for the positive electrode and copper is used for the negative electrode.

[0017] The terminal part 6 will be described. FIG. 5 is a cross-sectional view of the terminal part 6 in the lid body 5. What is shown in FIG. 5 is a longitudinal cross-section parallel to the longitudinal direction of the lid body 5 indicated by arrows D and D in FIG. 1. The longitudinal cross-section of FIG. 5 is at a position near the center in the width direction of the lid body 5. As shown in FIG. 5, a through hole 14 is formed in the lid body 5. The through hole 14 is shaped to pass the terminal member 9.

[0018] The lid body 5 and the terminal member 9 are not in contact. Between the lid body 5 and the terminal member 9, the aforementioned resin member 11 is provided. Due to the presence of the resin member 11, contact between the lid body 5 and the terminal member 9 is prevented. The resin member 11 also fills the through hole 14. By the resin member 11, the internal space of the case member 2 and the external space are blocked. The resin member 11 is formed in a state where the terminal member 9 is positioned with respect to the lid body 5. By the resin member 11, the lid body 5 and the terminal member 9 are integrated. In this embodiment, the terminal surface 8 and the outer surface 15 of the resin member 11 are substantially on the same plane.

[0019] As shown in FIG. 6, the resin member 11 includes an inner portion 16, a hole interior 17, and an outer portion 18. The inner portion 16 is a portion of the resin member 11 that is located below the lid body 5 in FIG. 5. Similarly, the hole interior 17 is a portion within the thickness range of the lid body 5 in FIG. 5. Similarly, the outer portion 18 is a portion located above the lid body 5. In other words, the inner portion 16 is a portion that contacts the inner surface 19 of the lid body 5. The hole interior 17 is a portion that fills the space between the wall surface of the through hole 14 and the terminal member 9. The outer portion 18 is a portion that contacts the outer surface 20 of the lid body 5. FIG. 6 shows only the resin member 11 for convenience of explanation. In reality, the resin member 11 having the shape shown in FIG. 6 does not exist as a single part.

[0020] When comparing the volumes of the inner portion 16 and the outer portion 18, the volume of the outer portion 18 is smaller. This is because, for the convenience of connecting the battery 1 and the external circuit, the protruding height from the outer surface 20 of the outer portion 18 and the terminal surface 8 cannot be made too large. This means that, regarding the expansion and contraction situation of the resin member 11 with respect to the lid body 5 in the case of a temperature change, the inner portion 16 with a larger volume becomes a more dominant factor than the outer portion 18.

[0021] In the battery 1, the magnitude relationship of the thermal expansion coefficients between the lid body 5 and the inner portion 16, and the magnitude relationship of the tensile strengths between the inner portion 16 and the outer portion 18 are made to satisfy special relationships. There are two types of special relationships, namely the first condition and the second condition, and either one of the conditions is satisfied.

[0022] The contents of the first and second conditions are as follows: Condition 1: The thermal expansion coefficient of the lid 5 is greater than that of the inner part 16, and the tensile strength of the inner part 16 is lower than the tensile strength of the outer part 18. Second condition: The thermal expansion coefficient of the lid 5 is smaller than that of the inner part 16, and the tensile strength of the outer part 18 is lower than that of the inner part 16.

[0023] Let's explain the first condition. Under the first condition, based on the relationship between the thermal expansion coefficients described above, the expansion and contraction of the lid 5 in response to temperature changes is more significant than the expansion and contraction of the inner part 16. Therefore, the lid 5 shown in Figure 5 will tend to curve downwards when cold and upwards when heated.

[0024] Focusing on cold conditions, the inner portion 16 is also curved downwards in a convex shape. This is because the upper surface of the inner portion 16 is dragged along by the contraction of the lid 5, causing it to contract more strongly than its original contraction. On the other hand, tensile stress is applied to the lower surface of the inner portion 16, which is the side that expands. This tensile stress is a factor that causes cracking in the inner portion 16, delamination from the terminal member 9, and delamination from the lid 5. However, under the first condition, because the inner portion 16 is highly flexible, cracking and delamination do not actually occur even in cold conditions.

[0025] Conversely, when the temperature rises, the outer part 18 becomes the stretching side, and tensile stress is applied to its upper surface. However, when the temperature rises, the resin softens to some extent due to the high temperature. Therefore, the outer part 18 also becomes somewhat flexible, and cracks or other damage do not occur in the outer part 18 when the temperature rises.

[0026] Let me explain the second condition. In the second condition, based on the relationship between the thermal expansion coefficients described above, the expansion and contraction of the inner part 16 in response to temperature changes is more significant than the expansion and contraction of the lid 5. Therefore, contrary to the case of the first condition, the lid 5 tends to curve upward when it is cold and downward when it is warm.

[0027] Focusing on cold conditions, the outer part 18 is also curved upward in a convex shape. This is because the lower surface of the outer part 18 is dragged along by the contraction of the lid 5, causing it to contract more strongly than its original contraction. On the other hand, tensile stress is applied to the upper surface of the outer part 18. This tensile stress is a factor that causes cracking and delamination in the outer part 18. However, under the second condition, because the outer part 18 is highly flexible, cracking and delamination do not actually occur even in cold conditions.

[0028] When the temperature rises, tensile stress is applied to the lower surface of the inner part 16. However, when the temperature rises, the resin of the inner part 16 softens to some extent due to the high temperature. Therefore, cracks and other damage do not occur in the inner part 16 when the temperature rises.

[0029] As described above, in this form of battery 1, by satisfying either the first or second condition, the occurrence of cracking and delamination in the resin component 11 is suppressed, both in cold and warm conditions. For this reason, battery 1 has excellent durability against thermal cycles.

[0030] As described above, in this embodiment, the resin member 11 has different properties between the inner part 16 and the outer part 18. At least the tensile strength differs between the inner part 16 and the outer part 18. The coefficient of thermal expansion may also differ between the inner part 16 and the outer part 18. There are three methods for imparting such different properties to the inner part 16 and the outer part 18. • A method using a composite resin containing fillers as the resin component 11, with differences in the filler's blending ratio. • A method using a composite resin containing an elastomer as the resin component 11, with differences in the blending ratio of the elastomer. • A method using different types of base resins.

[0031] The method using fillers will be explained. Fillers are minute solid particles. For example, glass fibers, glass powder, etc., can be used as fillers. Assuming the base resin is the same, the higher the filler content, the higher the tensile strength of the composite resin. Therefore, in the first condition, the outer part 18 has a higher filler content than the inner part 16, and in the second condition, the inner part 16 has a higher filler content than the outer part 18.

[0032] Assuming the same base resin, the higher the filler content, the smaller the thermal expansion coefficient of the composite resin. If the base resin of the resin component 11 is, for example, PPS resin, and the material of the lid 5 is, for example, aluminum, then the thermal expansion coefficient of the base resin will be nearly twice that of the lid 5.

[0033] In the first condition, the filler content in the inner part 16 is increased to such an extent that the thermal expansion coefficient of the composite resin in the inner part 16 is lower than that of aluminum. The filler content in the outer part 18 under the first condition is even higher. In the second condition, the filler content in the inner part 16 is reduced to such an extent that the thermal expansion coefficient of the composite resin in the inner part 16 is not lower than that of aluminum. The filler content in the outer part 18 under the second condition is even lower. When using a filler, either the first or second condition is met by adjusting the filler content as described above.

[0034] Let's explain the method using elastomers. Elastomers are polymer materials with a low elastic modulus and viscoelastic properties. Assuming the base resin is the same, the lower the elastomer blending ratio, the higher the tensile strength of the composite resin. Therefore, in the first condition, the inner part 16 has a higher elastomer blending ratio than the outer part 18, and in the second condition, the outer part 18 has a higher elastomer blending ratio than the inner part 16.

[0035] Assuming the same base resin, the lower the elastomer blending ratio, the smaller the thermal expansion coefficient of the composite resin. In the first condition, the elastomer blending ratio in the inner part 16 is kept low so that the thermal expansion coefficient of the composite resin in the inner part 16 is lower than that of aluminum. The elastomer blending ratio in the outer part 18 in the first condition is even lower. In the second condition, the elastomer blending ratio in the inner part 16 is increased so that the thermal expansion coefficient of the composite resin in the inner part 16 is not lower than that of aluminum. The elastomer blending ratio in the outer part 18 in the second condition is even higher. In the method using elastomers, either the first or second condition is satisfied by adjusting the elastomer blending ratio as described above.

[0036] This section describes a method using different types of base resins. For example, even with PPS resin, there are various types depending on factors such as molecular weight and the degree of crosslinking. The resin type for the inner part 16 and the resin type for the outer part 18 should be selected so that either the first or second condition is met.

[0037] Although the interior of the hole 17 was not mentioned in the description of the resin member 11 above, the properties of the interior of the hole 17 may be the same as either the inner part 16 or the outer part 18. Alternatively, the boundary between the part with the same properties as the inner part 16 and the part with the same properties as the outer part 18 may be located in the middle of the interior of the hole 17.

[0038] The resin member 11, which has parts made of two different resin types with different properties, is molded using two types of raw resin. With the terminal member 9 positioned and held in the through hole 14 of the lid 5, the raw resin for the inner part 16 is supplied from below to form the inner part 16. Alternatively, the inner part 16 and the inside of the hole 17 are formed. Then, the raw resin for the outer part 18 is supplied from above to form the outer part 18. Alternatively, the outer part 18 and the inside of the hole 17 are formed. When using a composite resin, the addition of fillers or elastomers to the base resin is completed in advance.

[0039] If the base resins of the inner part 16 and the outer part 18 are of the same type or have high affinity, a mixed layer may be formed at the contact point between the two resin types depending on the molding conditions. In that case, there is an advantage that delamination between the two resin types is less likely to occur during subsequent thermal cycles.

[0040] Next, the anchor structure of the terminal section 6 will be described. In the terminal section 6 of the battery 1 in this embodiment, an anchor structure is provided at the joint surface between the metal parts (cover 5 and terminal member 9) and the resin member 11. The anchor structure is provided within the area of ​​the surface of the metal parts that is covered by the resin member 11. The anchor structure is a rough surface region where the metal and resin interlock. In Figure 5, the portion of the anchor structure that is visible in the cross-sectional view is indicated by a thick line 21.

[0041] In the anchor structure, the metal member and the resin member 11 interlock with each other. Therefore, the adhesion between the metal part and the resin member 11 is good in the anchor structure, making delamination less likely. On the other hand, this also means that the resin member 11 is prone to cracking in situations where the lid 5 is likely to bend, such as during cold or warming conditions. Cracks are more likely to occur on the side of the resin member 11 that is subjected to tensile stress, between the inner part 16 and the outer part 18. With the anchor structure in place, the tensile stress is not relieved by delamination between the metal part and the resin member 11, thus making cracking more likely. However, in this embodiment of the resin member 11, the properties of the inner part 16 and the outer part 18 are appropriately set, as described in the first or second condition above. Therefore, even with the anchor structure in place, cracking is less likely to occur.

[0042] The parts of the lid 5 and terminal member 9 that are to become anchor structures are pre-treated to create a rough surface. Fine irregularities of a size of several tens to several hundred nanometers are formed in the areas where the rough surface treatment has been applied. When the resin member 11 is molded, the raw resin flows into the recesses of these irregularities, forming the anchor structure.

[0043] Figures 2 and 3 show the roughening range 22, which is the area in the terminal member 9 where the roughening treatment is applied. From the level of the lower surface 23 of the terminal member 9 facing the outside 24 Intermediate section 13 The roughened area 22 extends to about the middle of the surface. The bottom surface 23 is also roughened. The terminal surface 8 is not roughened. There is no need to strictly define the lower limit of the roughened area 22. It is not a problem if the roughened area 22 extends below the area that will come into contact with the resin member 11.

[0044] The above describes the resin member 11 of terminal section 6, but the same applies to the resin member 11 of terminal section 7. An anchor structure can also be provided in terminal section 7. The roughening range of the terminal member 10 for this purpose is no different from that shown in Figures 2 and 3.

[0045] As described in detail above, according to this embodiment, the resin member 11 between the lid 5, the terminal member 9 that penetrates it, and 10 is made to satisfy the first or second condition mentioned above. This prevents cracking of the resin member 11. In particular, cracking is less likely to occur even in areas that expand in cold temperatures, which are normally prone to cracking. As a result, a battery 1 with excellent durability against thermal cycles is realized.

[0046] These embodiments and examples are merely illustrative and do not limit the disclosed technology in any way. Therefore, the disclosed technology can naturally be improved and modified in various ways without departing from its essence. For example, the type of battery 1 is not limited. It may be a lithium-ion battery, nickel-metal hydride battery, solid-state battery, or anything else. The parts of the battery 1 to which the disclosed technology is applied may be both the positive and negative terminals 6 and 7, or only one of them.

[0047] As the raw material resin for the resin member 11, a composite resin may be used, which is a base resin blended with both a filler and an elastomer. The resin type of the base resin of the resin member 11 may be something other than PPS resin. The material of the lid 5 may be a metal other than aluminum. The range of the anchor structure in the terminal members 9, 10 and the lid 5 may be only a part of the range that comes into contact with the resin of the resin member 11, rather than the entire range. [Explanation of Symbols]

[0048] 1 battery 2 Case components 3 Power generation elements 4 box body 5. Lid 8 Terminal surface 9 Terminal members 10 Terminal members 11 Resin component 12 Connection part 13. Middle section 14 Through holes 16. Inside 17 Inside the hole 18 Outer part 21 Thick line 22. Roughening range 24 External Relations

Claims

1. A case component containing a power generation element, A terminal member connected to the power generation element and provided through the case member, The case member and the terminal member are insulated and sealed by a resin member, The case member has a through hole formed therein for the terminal member to pass through. The aforementioned resin member includes: The inner part that is in contact with the inner surface of the case member, The inside of the hole fills the space between the wall surface of the through hole and the terminal member, The case member includes an outer portion that is in contact with the outer surface and has a smaller volume than the inner portion, The case member satisfies either of the following conditions: a first condition in which the coefficient of thermal expansion of the case member is greater than the coefficient of thermal expansion 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 coefficient of thermal expansion of the case member is less than the coefficient of thermal expansion of the inner part and the tensile strength of the outer part is lower than the tensile strength of the inner part. The resin member contains a filler, If the first condition is met, the filler content of the inner part is lower than the filler content of the outer part. A battery in which the filler content of the inner part is higher than the filler content of the outer part, provided that the second condition is met.

2. A case component containing a power generation element, A terminal member connected to the power generation element and provided through the case member, The case member and the terminal member are insulated and sealed by a resin member, The case member has a through hole formed therein for the terminal member to pass through. The aforementioned resin member includes: The inner part that is in contact with the inner surface of the case member, The inside of the hole fills the space between the wall surface of the through hole and the terminal member, The case member includes an outer portion that is in contact with the outer surface and has a smaller volume than the inner portion, The case member satisfies either of the following conditions: a first condition in which the coefficient of thermal expansion of the case member is greater than the coefficient of thermal expansion 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 coefficient of thermal expansion of the case member is less than the coefficient of thermal expansion of the inner part and the tensile strength of the outer part is lower than the tensile strength of the inner part. The aforementioned resin member contains an elastomer, If the first condition is met, the elastomer content of the inner part is higher than the elastomer content of the outer part. A battery in which the elastomer content of the inner part is lower than the elastomer content of the outer part, provided that the second condition is met.

3. A battery according to claim 1 or claim 2, A battery in which the base material resin of the inner part and the base material resin of the outer part are of the same type.

4. A battery according to claim 1 or claim 2, A battery in which a rough surface region is provided on at least a portion of the surface of the case member that is covered by the resin member and on the surface of the terminal member that is covered by the resin member, in which the metal and resin are interlocked.

Images