JP2007179793A - Cover for sealed battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cover for a sealed battery capable of improving a yield by preventing cleavage of a thin part in manufacturing, and thereby reducing a cost, in a cover for a sealed battery having a thin part, and insulated sealing members for fixing electrode terminals by insert molding. <P>SOLUTION: An upper lid 1 of a lithium battery 1 is composed of the cover 120, a safety valve 121, a rib 122, positive-electrode and negative-electrode terminals 123 and 124, and insulating sealing members 125 and 126 made of a resin. The rib 122 projecting in the plate thickness direction is formed in a square frame-like shape around the safety valve 121 to surround the whole circumference thereof by being separated from the safety valve 121 at a distance. Stress applied to the safety valve 121 and associated with deformation can be relieved by the rib 122. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lid for a sealed battery.

In recent years, lithium batteries with large capacity, high output, and high energy density have attracted attention as in-vehicle power sources for driving automobiles. As such a lithium battery, a battery including an electrode body and an electrode terminal, housed in a container, and sealed by a lid body is generally known. The electrode body is configured by arranging a positive electrode made of a metal foil coated with a positive electrode active material and a negative electrode coated with a negative electrode active material mainly composed of LiNiO _{2 and the} like, with a separator interposed therebetween. The electrode body is impregnated with a non-aqueous electrolyte. The electrode terminal includes a positive electrode terminal and a negative electrode terminal, and is fixed to the lid body in an insulated state. The positive electrode is electrically connected to the positive electrode of the electrode body, and the negative electrode terminal is electrically connected to the negative electrode. The thus configured electrode body and electrode terminal are accommodated in, for example, a rectangular parallelepiped container having an opening at one end, and are sealed by a lid.

  By the way, the performance of lithium batteries deteriorates when moisture enters the container. This is because the water that has entered the container reacts with the non-aqueous electrolyte to generate hydrofluoric acid. When hydrofluoric acid is generated, the electrodes constituting the electrode body are eroded, causing a reduction in battery capacity and battery life. For this reason, it is necessary to ensure a sufficient sealing property between the lid and the electrode terminal, which is particularly susceptible to moisture. 2. Description of the Related Art Conventionally, as a lid that can ensure hermeticity between electrode terminals, for example, there is a lid of an electric double layer capacitor container disclosed in Japanese Patent Application Laid-Open No. 2002-237436. The lid includes an insulating sealing member made of resin formed by insert molding between the electrode terminals. Thereby, the sealing property between a cover body and an electrode terminal is securable.

Further, when the lithium battery is overcharged or charged with a current larger than a prescribed current, gas is generated in the container. Since the container is sealed by the lid, when gas is generated, the pressure in the container rises and the container expands. As the pressure rises further, the container cracks. If a crack occurs, the electrolyte in the container leaks, and there is a risk of adversely affecting the devices disposed around. Therefore, it is necessary to suppress an increase in pressure in the container. 2. Description of the Related Art Conventionally, as a lid that can suppress an increase in pressure in a container, for example, there is a sealed battery sealing plate disclosed in JP-A-2002-367583. This sealing plate is provided with a recess in a predetermined region on the surface. Furthermore, the bulging part enclosed by the groove | channel is formed in the bottom part of a recessed part. When the pressure in the container rises and exceeds a predetermined value, the bottom of the recess breaks along the groove, and the bulging portion bulges. Therefore, the space in the container communicates with the outside, and the pressure in the container decreases. Thereby, the rise in pressure is suppressed and the occurrence of expansion and cracking of the container can be prevented.
JP 2002-237436 A Japanese Patent Laid-Open No. 2002-367583

  By the way, when insert molding is performed, a very high molding pressure is applied to the object. For this reason, when an insulating sealing member is formed by insert molding on the lid body in which the concave portion is formed and the electrode terminal is fixed, the lid body is deformed by the molding pressure at the time of insert molding, and the concave portion is broken. was there. Thereby, the yield at the time of manufacture fell and it was difficult to hold down cost.

  The present invention has been made in view of such circumstances, and in a sealed battery lid having a thin-walled portion and an insulating sealing member that fixes an electrode terminal by insert molding, the thin-walled portion is split at the time of manufacture. An object of the present invention is to provide a lid for a sealed battery that can improve the yield and reduce the cost.

Means for Solving the Problems and Effects of the Invention

  Therefore, as a result of intensive research and trial and error in order to solve this problem, the present inventor has obtained a thick part surrounding the thin part at least partially around the thin part, or another thin part thicker than the thin part. By providing the portion, it was conceived that the thin-walled portion could be prevented from being cracked during production, and the present invention was completed.

  That is, the cooling device of the present invention includes a plate-like lid made of metal that closes the opening of the container of the sealed battery and the lid, and is cleaved when the pressure in the container exceeds a predetermined pressure. A thin-walled portion that is thinner than the other part of the lid body, and an electrode terminal that is inserted into a through-hole formed in the lid body. In a sealed battery lid body that is insert-molded between the lid body and the electrode and has an insulating sealing member that insulates and integrally fixes the lid body and the electrode, the thin wall of the lid body Around the portion, there is a thick portion that is thicker than the other portion of the lid other than the thin portion in the thickness direction dimension that at least partially surrounds the thin portion.

  According to this configuration, it is possible to improve the yield and reduce the cost by preventing the thin-walled portion from being broken during manufacturing. When the insulating sealing member is insert-molded, the lid body is deformed by the molding pressure. However, a thick part thicker than the other part of the lid that at least partially surrounds the thin part is provided around the thin part. Therefore, the stress accompanying deformation applied to the thin portion can be reduced by the thick portion. Thereby, the tearing of the thin part at the time of manufacture is prevented, the yield is improved, and the cost can be reduced. The thick part may be provided so as to partially surround the thin part, or may be provided so as to surround the entire periphery of the thin part. It is more preferable to surround the entire periphery of the thin portion because the stress can be reliably reduced. In addition, the thick part may be provided at a distance from the thin part, or at least part of the thick part may be provided in contact with the thin part. Furthermore, a groove may be provided on the surface of the thin portion in order to more reliably cleave the thin portion.

  Here, the thin-walled portion can be formed by compressing the lid, and the thick-walled portion can be formed by the surplus thickness generated during compression molding. Thereby, a thick part can be formed reliably. Moreover, you may form a thin part and a thick part simultaneously. Thereby, a manufacturing process can be simplified and cost can further be reduced.

  In addition, the cooling device of the present invention is formed on the lid body made of metal for closing the opening of the container of the sealed battery, and when the pressure in the container becomes equal to or higher than a predetermined pressure. The first thin-walled portion that is cleaved and communicates the space in the container with the space outside the container in the thickness direction is thinner than the other part of the lid, and is inserted into the through-hole formed in the lid. In a sealed battery lid having an electrode terminal and an insulating sealing member that is insert-molded between the lid and the electrode and insulates and integrally fixes the lid and the electrode. Around the first thin portion of the body, the thickness in the thickness direction surrounding at least partially the first thin portion is thicker than the first thin portion, and the lid other than the first thin portion It has the 2nd thin part thinner than a part, It is characterized by the above-mentioned.

  Also in this configuration, similarly to the configuration described above, it is possible to prevent the first thin portion from being cleaved during manufacturing, improve the yield, and reduce the cost. When the insulating sealing member is insert-molded, the lid body is deformed by the molding pressure. However, around the thin portion, a second thin portion that is thinner than the other portion of the lid other than the first thin portion that at least partially surrounds the first thin portion is provided. Therefore, the stress accompanying the deformation is concentrated on the second thin portion. However, the second thin portion does not break thicker than the first thin portion. Thereby, the stress accompanying the deformation | transformation added to a 1st thin part can be reduced by a 2nd thin part. Accordingly, it is possible to prevent the first thin-walled portion from being cleaved during manufacturing, improve the yield, and reduce the cost. The second thin part may be provided so as to partially surround the first thin part, or may be provided so as to surround the entire periphery of the first thin part. It is more preferable to surround the entire periphery of the first thin portion because the stress can be reliably reduced. The second thin portion may be provided at a distance from the first thin portion, or may be provided so that at least a part thereof is in contact with the first thin portion. Furthermore, a groove may be provided on the surface of the first thin portion in order to more reliably cleave the first thin portion.

  Here, the first thin portion and the second thin portion can be simultaneously formed by compression molding the lid. Thereby, a 2nd thin part can be formed cheaply and reliably compared with cutting.

  Next, an embodiment is given and this invention is demonstrated in detail. In the present embodiment, an example in which the sealed battery lid according to the present invention is applied to an upper lid of a lithium battery used as an in-vehicle power source is shown.

(First embodiment)
First, the configuration of the lithium battery in the first embodiment will be described with reference to FIG. FIG. 1 is a perspective view showing a configuration of a lithium battery.

As shown in FIG. 1, the lithium battery 1 includes an electrode body 10, a case 11, and an upper lid 12. The electrode body 10 is a member that generates DC power by a chemical reaction. The electrode body 10 includes a positive electrode made of, for example, an aluminum foil coated with a positive electrode active material, and a negative electrode made of, for example, a copper foil coated with a negative electrode active material mainly composed of LiNiO ₂ or the like. It is arranged to be opposed to each other through a separator made of a porous sheet and further wound. The electrode body is impregnated with an electrolytic solution. The case 11 is a rectangular parallelepiped member that houses the electrode body 10 and has an opening at one end on the upper side made of, for example, aluminum. The upper lid 12 is a member that seals the opening of the case and supplies DC power generated by the electrode body to the outside via the positive terminal and the negative terminal. The electrode body 10 is connected to the positive electrode terminal and the negative electrode terminal of the upper lid 12, accommodated in the case 11 and sealed.

  Next, the upper lid according to the present invention will be described in detail with reference to FIGS. FIG. 2 is a perspective view of the upper lid. FIG. 3 is a top view of the lid in FIG. 4 is a cross-sectional view taken along arrow AA in FIG.

  As shown in FIG. 2, the upper lid 12 includes a lid body 120, a safety valve 121 (thin wall portion), a rib 122 (thick wall portion), a positive electrode terminal 123 (electrode terminal), and a negative electrode terminal 124 (electrode terminal). Insulating sealing members 125 and 126 made of resin.

  The lid 120 is a rectangular plate-like member made of, for example, aluminum that closes and seals the opening of the case 11. As shown in FIGS. 3 and 4, rectangular through holes 120 a and 120 b through which the positive electrode terminal 123 and the negative electrode terminal 124 are inserted are provided in the vicinity of the end in the longitudinal direction of the lid 120. A safety valve 121 is formed at the center in the longitudinal direction.

  The safety valve 121 is cleaved when the pressure in the sealed case 11 becomes equal to or higher than a predetermined pressure, and communicates the space in the case 11 with the space outside the case 11. It is a square-shaped part thinner (t <T) than the other part (T) of the lid 120. The dimension of the safety valve 121 in the plate thickness direction is set to a dimension that allows the safety valve 121 to be cleaved when the pressure in the case 11 exceeds a predetermined pressure. Around the safety valve 121, a rib 122 protruding in the thickness direction is formed in a square frame shape so as to surround the entire outer periphery with a space from the safety valve 121. As a result, a portion surrounding the entire outer periphery of the safety valve 121 and having a thickness in the thickness direction that is thicker than the other part of the lid 120 excluding the safety valve 121 is formed. Here, the safety valve 121 is formed by compression-molding the lid 120. Further, the rib 122 is formed by a surplus generated when the safety valve 121 is compression molded. Therefore, the safety valve 121 and the rib 122 can be formed at the same time by compression-molding the lid 120 with a mold.

  Returning to FIG. As shown in FIG. 2, the positive electrode terminal 123 is a rectangular plate-shaped member made of, for example, aluminum. The negative terminal 124 is a rectangular plate member made of, for example, copper. The positive electrode terminal 123 and the negative electrode terminal 124 are set to dimensions that do not make electrical contact with the lid body 120 when inserted into the through holes 120a and 120b (not shown). The positive electrode terminal 123 and the negative electrode terminal 124 are insulated and integrally formed by resin insulating sealing members 125 and 126 insert-molded between the lid body 120 with the upper ends protruding above the lid body 120. Fixed. Further, the positive electrode terminal 123 and the negative electrode terminal 124 are subjected to electrochemical surface treatment, and a coating layer is formed on the surface.

Example 1
Next, Example 1 which is an Example in 1st Embodiment is demonstrated with reference to FIGS. 3 and 4, the lid body 120 of Example 1 is made of aluminum, and the dimensions thereof are length (L) × width (W) × plate thickness (T) of 100 mm × 12 mm × 0.8 mm. . The dimensions of the through holes 120a and 120b are 10 mm x 5 mm in length (l) x width (w). Furthermore, the dimension (t) of the safety valve 121 in the plate thickness direction is 0.1 mm. Around the safety valve 121, a rib 122 protruding in the thickness direction is formed so as to surround the entire outer periphery with a space from the safety valve 121. As shown in FIG. 2, a resin insulating sealing member 125 is formed by insert molding between the positive electrode terminal 123 and the negative electrode terminal 124 through the through holes 120 a and 120 b of the cover body 120 and the cover body 120. , 126 are formed to form the upper lid 12.

(Comparative example)
Next, a comparative example will be described with reference to FIGS. FIG. 5 is a top view of the lid in the comparative example. 6 is a cross-sectional view taken along the line BB in FIG. FIG. 7 is a perspective view of an upper lid in a comparative example.

  As shown in FIGS. 5 and 6, the lid 120 ′ of the comparative example corresponds to a conventional lid, and is different from the lid 120 of the first embodiment in that only the rib 122 is not provided. The material and other dimensions are the same as those of the lid 120 of the first embodiment. 5 and 6, the lid 120 ′ is made of aluminum, and the dimensions are such that length (L) × width (W) × plate thickness (T) is 100 mm × 12 mm × 0.8 mm. The dimensions of the through holes 120a 'and 120b' are 10 mm x 5 mm in length (l) x width (w). Furthermore, the dimension (t) of the safety valve 121 in the plate thickness direction is 0.1 mm. Then, as shown in FIG. 7, in the same manner as in the first embodiment, the lid body 120 is inserted with the positive electrode terminal 123 and the negative electrode terminal 124 inserted into the through holes 120a ′ and 120b ′ of the lid body 120 ′. The upper lid 12 'is formed by forming resin insulating sealing members 125 and 126 by insert molding.

(Evaluation results)
Next, an evaluation result will be described with reference to FIG. FIG. 8 is a diagram showing an evaluation result in the first embodiment. Ten upper lids 12 of Example 1 and 10 upper lids 12 ′ of comparative examples were manufactured, and the presence or absence of cleavage of safety valves 121 and 121 ′ was evaluated. As shown in FIG. 8, in the comparative example, the safety valve 121 ′ was cleaved in four out of ten. On the other hand, in Example 1, the safety valve 121 was not cleaved at all.

  Finally, the effect will be described. As shown in FIG. 8, according to the upper lid 12, the safety valve 121 can be prevented from being broken at the time of manufacture, the yield can be improved, and the cost can be reduced. When the resin insulating sealing members 125 and 126 are insert-molded, the lid 120 is deformed by the molding pressure. However, a rib 122 protruding in the thickness direction is formed in a square frame shape around the safety valve 121 so as to surround the entire outer periphery of the safety valve 121. As a result, a portion surrounding the entire outer periphery of the safety valve 121 and having a thickness in the thickness direction that is thicker than the other part of the lid 120 excluding the safety valve 121 is formed. Therefore, the stress accompanying the deformation | transformation added to the safety valve 121 by the rib 122 can be reduced. Thereby, the safety valve 121 is prevented from being broken at the time of manufacturing, the yield is improved, and the cost can be reduced.

  Moreover, the rib 122 can be reliably formed by using the surplus when the lid 120 is compression-molded to form the safety valve 121.

  Furthermore, by compressing and molding the lid 120 with a mold and simultaneously forming the safety valve 121 and the rib 122, the manufacturing process can be simplified and the cost can be further reduced.

  In the first embodiment, the rib 122 surrounds the entire outer periphery with a space from the safety valve 121, but the present invention is not limited to this. As shown in FIGS. 9 and 10, a C-shaped rib 122 a having a discontinuous portion on the long side of the lid 120 may be used. Moreover, as shown in FIG.11 and FIG.12, the U-shaped ribs 122b and 122c which oppose on both sides of the safety valve 121 in the long side direction of the cover body 120 may be sufficient. Furthermore, as shown in FIGS. 13 and 14, linear ribs 122 d and 122 e extending in the long side direction facing the safety valve 121 in the short side direction of the lid 120 may be used.

(Second Embodiment)
Next, the lithium battery according to the second embodiment will be described with reference to FIGS. FIG. 15 is a perspective view of an upper lid in the second embodiment. FIG. 16 is a top view of the lid in FIG. 17 is a cross-sectional view taken along the line FF in FIG. The lithium battery in 2nd Embodiment replaces the rib formed in the circumference | surroundings of a safety valve with the groove part with respect to the lithium battery in 1st Embodiment. Here, only the groove part which is different from the lithium battery in the first embodiment will be described, and the description of the common part will be omitted except for the necessary part. In addition, the same code | symbol is attached | subjected and demonstrated to the element same as 1st Embodiment.

  As shown in FIG. 15, the upper lid 12 includes a lid body 120, a safety valve 121 (first thin portion), a groove portion 127 (second thin portion), a positive terminal 123 (electrode terminal), and a negative terminal 124 (electrode). Terminal) and resin insulating sealing members 125 and 126. As shown in FIGS. 16 and 17, a groove 127 having a rectangular cross section is formed in a square frame shape around the safety valve 121 so as to surround the entire outer periphery with a space from the safety valve 121. The dimension (t2) of the bottom part of the groove part 127 in the plate thickness direction is set to be thicker than the safety valve 121 (t1) and thinner than the other part (T) of the lid 120 excluding the safety valve 121. Here, the safety valve 121 and the groove 127 can be simultaneously formed by compression-molding the lid 120 with a mold.

(Example 2)
Next, Example 2 which is an Example in 2nd Embodiment is demonstrated with reference to FIGS. 16 and 17, the lid body 120 of Example 2 is made of aluminum, and the dimensions thereof are length (L) × width (W) × plate thickness (T) of 100 mm × 12 mm × 0.8 mm. . The dimensions of the through holes 120a and 120b are 10 mm x 5 mm in length (l) x width (w). Furthermore, the dimension (t1) of the safety valve 121 in the plate thickness direction is 0.1 mm. A rectangular groove 127 is formed around the safety valve 121 so as to surround the entire outer periphery with a distance from the safety valve 121. The dimension (t2) in the thickness direction of the bottom part of the groove part 127 is 0.2 mm. Then, as shown in FIG. 15, a resin insulating sealing member 125 is formed by insert molding with the lid body 120 with the positive electrode terminal 123 and the negative electrode terminal 124 inserted through the through holes 120 a and 120 b of the lid body 120. , 126 are formed to form the upper lid 12.

(Evaluation results)
Next, evaluation results will be described with reference to FIG. FIG. 18 is a diagram illustrating an evaluation result in the second embodiment. Ten upper lids 12 of Example 2 and 10 upper lids 12 ′ of the comparative examples described above were manufactured, and the presence or absence of cleavage of safety valves 121 and 121 ′ was evaluated. As shown in FIG. 18, in the comparative example, the safety valve 121 ′ was cleaved in four out of ten. On the other hand, in Example 2, the safety valve 121 was not broken at all.

  Finally, the effect will be described. As shown in FIG. 18, according to the upper lid 12, it is possible to prevent the safety valve 121 from being broken at the time of manufacturing, improve the yield, and reduce the cost. When the resin insulating sealing members 125 and 126 are insert-molded, the lid 120 is deformed by the molding pressure. However, a groove 127 thinner than the other part of the lid 120 excluding the safety valve 121 is provided around the safety valve 121 so as to surround the entire circumference of the safety valve 121. Therefore, the stress accompanying the deformation is concentrated on the groove 127. However, the groove 127 does not break thicker than the safety valve 121. Thereby, the stress accompanying deformation applied to the safety valve 121 can be reduced by the groove 127. Therefore, the safety valve 121 is prevented from being broken during manufacturing, yield is improved, and cost can be reduced.

  Further, by compressing and molding the lid 120 with a mold and simultaneously forming the safety valve 121 and the groove portion 127, the groove portion 127 can be formed cheaply and reliably as compared with the cutting process.

  In the second embodiment, an example is given in which the groove 127 surrounds the entire outer periphery with an interval from the safety valve 121, but is not limited thereto. As shown in FIGS. 19 and 20, a C-shaped groove 127 a having a discontinuous portion on the long side of the lid 120 may be used. Further, as shown in FIGS. 21 and 22, U-shaped grooves 127 b and 127 c facing each other across the safety valve 121 may be provided in the long side direction of the lid 120. Furthermore, as shown in FIGS. 23 and 24, linear grooves 127d and 127e extending in the long side direction and facing each other with the safety valve 121 interposed therebetween may be provided in the short side direction of the lid 120.

It is a lithium battery perspective view in a 1st embodiment. It is a perspective view of an upper lid. It is a top view of the cover body in FIG. It is AA arrow sectional drawing in FIG. It is a top view of the cover in a comparative example. It is BB arrow sectional drawing in FIG. It is a perspective view of the upper cover in a comparative example. It is a figure which shows the evaluation result in 1st Embodiment. It is a top view of the cover in another form. It is CC sectional view taken on the line in FIG. It is a top view of the cover in another form. It is DD sectional view taken on the line in FIG. It is a top view of the cover in another form. It is EE arrow sectional drawing in FIG. It is a perspective view of the upper lid in a 2nd embodiment. FIG. 16 is a top view of the lid body in FIG. 15. It is FF arrow sectional drawing in FIG. It is a figure which shows the evaluation result in 2nd Embodiment. It is a top view of the cover in another form. It is GG arrow sectional drawing in FIG. It is a top view of the cover in another form. It is HH arrow sectional drawing in FIG. It is a top view of the cover in another form. It is II sectional view taken on the line in FIG.

Explanation of symbols

1: Lithium battery, 10: Electrode body, 11: Case, 12: Upper lid (lid battery lid), 120: Lid body, 120a, 120b: Through hole, 121: Safety valve (thin portion, first thin portion) 122, 122a to 122e: ribs (thick portions), 123: positive terminals (electrode terminals), 124: negative terminals (electrode terminals), 125, 126: insulating sealing members made of resin, 127, 127a to 127e: grooves ( (Second thin portion), 120 ′: lid, 120a ′, 120b ′: through hole, 121 ′: safety valve, 123 ′: positive terminal, 124 ′: negative terminal, 125 ′, 126 ′: insulating insulating sealing member made of resin

Claims (4)

A plate-like lid made of a metal that closes the opening of the container of the sealed battery, and the lid is formed on the lid, and is cleaved when the pressure in the container exceeds a predetermined pressure, thereby opening the space in the container A thin-walled portion whose dimension in the plate thickness direction that communicates with the outside space is thinner than the other part of the lid, an electrode terminal inserted through a through-hole formed in the lid, and a gap between the lid and the electrode In a sealed battery lid having an insulating sealing member that is insert-molded and insulates and integrally fixes the lid and the electrode,
A hermetic portion characterized by having a thick-walled portion around the thin-walled portion of the lid that is thicker than other portions of the lid other than the thin-walled portion in the thickness direction surrounding the thin-walled portion at least partially. Type battery cover. The thin portion is formed by compression molding the lid,
2. The sealed battery lid according to claim 1, wherein the thick portion is formed by a surplus generated during the compression molding. A plate-shaped lid made of metal for closing the opening of the container of the sealed battery, and a lid formed on the lid, which is cleaved when the pressure in the container exceeds a predetermined pressure to open the space in the container A first thin-walled portion whose dimension in the plate thickness direction communicating with the space outside the container is thinner than the other part of the lid, an electrode terminal inserted through a through-hole formed in the lid, the lid and the lid In a sealed battery lid body that is insert-molded with an electrode and has an insulating sealing member that insulates and integrally fixes the lid body and the electrode,
Around the first thin portion of the lid, the thickness in the plate thickness direction surrounding at least partially the first thin portion is thicker than the first thin portion, and the lid other than the first thin portion A sealed battery lid characterized by having a second thin part thinner than the other part.   4. The sealed battery lid according to claim 3, wherein the first thin portion and the second thin portion are simultaneously formed by compression-molding the lid. 5.

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