Battery

Abstract

To provide a battery with a highly reliable gas discharge valve. [Solution] The battery 1 comprises a metal case 2 with a through hole 20 formed in the lid 10, and a thermoplastic resin gas discharge valve 100 provided in the through hole 20. The gas discharge valve 100 has a shaft portion 110 located inside the through hole 20, and outer and inner enlarged portions 120 and 130 provided at both ends of the shaft portion 110, respectively, which are larger than the through hole 20. The inner enlarged portion 130 is inserted into the through hole 20 from the opening 21 on the side of the outer enlarged portion 120, and after passing through the through hole 20, it is larger than the through hole 20. A welded portion to the lid 10 is formed around the inner enlarged portion 130 so as to surround the through hole 20. A fracture point 135 is provided in an annular shape on the inner enlarged portion 130 in a region 136 corresponding to the inside of the through hole 20.

Description

Technical Field

[0001] The disclosed technology relates to a battery provided with a gas discharge valve in a case.

Background Art

[0002] Some batteries such as lithium ion secondary batteries are provided with a gas discharge valve that opens when the pressure inside the case rises beyond an allowable range and discharges the gas inside the case to the outside. For example, Patent Document 1 describes a configuration in which a sealed battery having a case formed by joining a container and a sealing plate that closes the opening thereof by laser welding is provided with a gas discharge valve. Further, Patent Document 1 describes that the gas discharge valve is integrally formed on a sealing plate made of metal.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, conventionally, generally metal has been adopted as the material of the gas discharge valve. In a gas discharge valve made of metal, for example, corrosion may occur depending on the elapsed time since the manufacturing time, the use environment, etc. And, the gas discharge valve made of metal tends to have a different opening pressure, which is the pressure inside the case leading to valve opening, depending on the degree of corrosion. For this reason, the gas discharge valve made of metal may have its reliability reduced due to corrosion.

[0005] The disclosed technology aims to provide a battery having a highly reliable gas discharge valve.

Means for Solving the Problems

[0006] One aspect of the disclosed technology is a battery comprising a metal case with a through hole formed in its wall, and a thermoplastic resin gas discharge valve provided at the location of the through hole. The gas discharge valve has a shaft located inside the through hole, and an outer enlargement portion and an inner enlargement portion provided at the outer and inner ends of the shaft, respectively, which are larger than the through hole. The one enlargement portion, which is one of the outer and inner enlargements, is inserted into the through hole from an opening on the other side of the through hole, which is different from the one enlargement portion, deforming to be smaller than the through hole, and after passing through the through hole, it is larger than the through hole. The inner enlargement portion has an inner welded portion formed around the through hole, which is welded to the case in a circle. The inner enlargement portion has a planned rupture point, which is provided in an annular shape in the region corresponding to the inside of the through hole, where it will rupture when the internal pressure of the case exceeds a predetermined upper pressure limit.

[0007] Another aspect of the technology disclosed herein is a battery comprising a metal case with a through hole formed in its wall, and a thermoplastic gas exhaust valve provided at the location of the through hole, wherein the gas exhaust valve has a shaft located inside the through hole, and an outer enlargement portion and an inner enlargement portion provided at the outer and inner ends of the shaft, respectively, which are larger than the through hole, and one of the outer and inner enlargements, the one enlargement portion, is inserted into the through hole from an opening on the other side of the through hole, which is different from the one enlargement portion, deforming to be smaller than the through hole, and after passing through the through hole, it is larger than the through hole, and the outer enlargement portion has an outer welded portion that is welded to the case in a circle surrounding the through hole, and the outer enlargement portion has a planned rupture location that is provided in an annular shape in the region inside the outer welded portion, which will rupture when the internal pressure of the case exceeds a predetermined upper pressure, and the inner enlargement portion has a planned rupture location that is provided in an annular shape in the region corresponding to the inside of the through hole.

[0008] The gas exhaust valve of the battery according to the above embodiment is made of thermoplastic resin. Therefore, deterioration such as corrosion in metal is suppressed, and changes in the valve opening pressure are suppressed. Thus, the battery according to the above embodiment has a highly reliable gas exhaust valve. [Effects of the Invention]

[0009] According to the disclosed technology, a battery having a highly reliable gas discharge valve is provided. [Brief explanation of the drawing]

[0010] [Figure 1] This is a perspective view of the battery according to the embodiment. [Figure 2] This is a cross-sectional view of the gas discharge valve and cover of the battery according to the first embodiment. [Figure 3] This figure shows the state in which the gas discharge valve of the battery according to the first embodiment is open. [Figure 4] This is a cross-sectional view of the gas discharge valve and cover of the battery according to the second embodiment. [Figure 5] This figure shows the state in which the gas discharge valve of the battery according to the second embodiment is open. [Figure 6] This figure shows an example in which a fire extinguishing agent and a desiccant are provided in the gas discharge valve of a battery according to the second embodiment. [Modes for carrying out the invention]

[0011] The embodiments of the disclosed technology will be described in detail below with reference to the attached drawings.

[0012] <First Embodiment> Figure 1 shows an external perspective view of the battery 1 according to the first embodiment. The battery 1 is, in general terms, a sealed battery in which an electrode body 3 is housed inside a case 2, as shown in Figure 1. The electrode body 3 is made up of a positive electrode plate 4A and a negative electrode plate 4B stacked together with an insulating separator 5 sandwiched between them.

[0013] Case 2 consists of a case body 6 and a lid 10. Both the case body 6 and the lid 10 are made of metal. The lid 10 is the wall portion that makes up the top of case 2. The electrolyte 7 is contained inside case 2. The lid 10 is provided with a positive electrode terminal 8A and a negative electrode terminal 8B. The positive electrode terminal 8A and the negative electrode terminal 8B are connected to the positive electrode plate 4A and the negative electrode plate 4B that make up the electrode body 3 inside case 2, respectively. As a result, the battery 1 can be charged or discharged via the positive electrode terminal 8A and the negative electrode terminal 8B.

[0014] Battery 1 has a gas discharge valve 100 provided in case 2. The gas discharge valve 100 opens when the internal pressure of case 2 reaches the opening pressure. In battery 1, the gas discharge valve 100 is provided in the lid 10. The gas discharge valve 100 is made of a thermoplastic resin and is elastic. Examples of thermoplastic resins that can be used to make up the gas discharge valve 100 include polypropylene (PP), polyvinylidene chloride (PVDC), polyvinylidene fluoride (PVDF), polycarbonate (PC), and polyphenylene sulfide (PPS). The gas discharge valve 100 is set to open at a pressure that allows the gas inside case 2 to be released to the outside when the internal pressure of case 2 exceeds a predetermined upper pressure. In this way, battery 1 is prevented from exceeding the allowable range of internal pressure in case 2.

[0015] Figure 2 is a cross-sectional view at position AA shown in Figure 1. Figure 2 shows cross-sections of the lid 10 and the gas exhaust valve 100. In Figure 2, the area above the lid 10 is the outside of the case 2, and the area below the lid 10 is the inside of the case 2.

[0016] A recess 15 is provided at the location of the gas discharge valve 100 on the outside of the lid body 10. The bottom surface of the recess 15 is a surface located outside the case 2, and in FIG. 2, the bottom surface of the recess 15 is shown as the outer surface 11. A through-hole 20 penetrating from the outer surface 11 to the inner surface 12 of the lid body 10 is formed in the lid body 10. The through-hole 20 of the present embodiment has a circular cross-sectional shape perpendicular to the depth direction. That is, both the outer opening 21 and the inner opening 22 of the through-hole 20 are circular.

[0017] The gas discharge valve 100 is provided at the location of the through-hole 20 in the lid body 10. The gas discharge valve 100 has a shaft portion 110, an outer enlarged portion 120, and an inner enlarged portion 130. The shaft portion 110 is located inside the through-hole 20. The outer enlarged portion 120 is provided at the end of the shaft portion 110 outside the case 2. The inner enlarged portion 130 is provided at the end of the shaft portion 110 inside the case 2. Both the outer enlarged portion 120 and the inner enlarged portion 130 have a shape that spreads wider than the through-hole 20. The outer enlarged portion 120 is housed inside the recess 15. Thereby, it is suppressed that the gas discharge valve 100 protrudes from the upper surface of the case 2. In the present embodiment, the shaft portion 110, the outer enlarged portion 120, and the inner enlarged portion 130 all have a circular cross-sectional shape perpendicular to the depth direction of the through-hole 20, similar to the through-hole 20.

[0018] In the present embodiment, the gas discharge valve 100 is assembled from the outside of the case 2 to the lid body 10. That is, the inner enlarged portion 130 is inserted into the through-hole 20 while being deformed smaller than the through-hole 20 from the outside in the through-hole 20, and after passing through the through-hole 20, it spreads wider than the through-hole 20. The inner enlarged portion 130 made of a thermoplastic resin is inserted into the through-hole 20 and becomes smaller than the through-hole 20 due to elastic deformation while passing through the inside of the through-hole 20. Further, after passing through the through-hole 20, the inner enlarged portion 130 returns to its original shape and spreads wider than the through-hole 20.

[0019] On the inner enlarged portion 130, an inner welded portion 131 welded to the lid body 10 is formed. The inner welded portion 131 is formed at a location on the lid body 10 side in the inner enlarged portion 130. Also, the inner welded portion 131 is continuously formed in a circle so as to surround the through hole 20. And the inner welded portion 131 functions as a seal portion that seals the location of the through hole 20 in the case 2. That is, the case 2 is sealed because the inner welded portion 131 is formed. Also, in this embodiment, since the inner enlarged portion 130 is wider than the through hole 20, when the pressure inside the case 2 increases compared to the pressure outside the case 2, the force acting on the inner welded portion 131, which is the seal portion, is reduced.

[0020] The inner welded portion 131 is formed by performing a heat treatment that raises the temperature of the location that becomes the inner welded portion 131 after passing the inner enlarged portion 130 through the through hole 20. In this embodiment, as the heat treatment for forming the inner welded portion 131, heating near the through hole 20 of the lid body 10 is performed. Thereby, the temperature of the location that becomes the inner welded portion 131 in the inner enlarged portion 130 can be raised, and the inner welded portion 131 can be formed.

[0021] For the heat treatment for forming the inner welded portion 131, for example, an infrared laser, a heater, etc. can be adopted. The heat treatment for forming the inner welded portion 131 is preferably performed while pressing the inner enlarged portion 130 against the lid body 10. This is because the inner enlarged portion 130 and the lid body 10 can be surely welded. The inner enlarged portion 130 can be pressed against the lid body 10, for example, by sucking the gas discharge valve 100 from the outside of the case 2.

[0022] Furthermore, the inner welding surface 14 on the inner surface 12 of the lid 10 in this embodiment, where the inner welding portion 131 is welded, is rougher than other parts of the inner surface 12. This inner welding surface 14 is provided by roughening the surface to create fine irregularities before assembling the gas exhaust valve 100 to the lid 10. Roughening can be performed, for example, using a laser. As a result, the inner welding portion 131 of the inner enlargement portion 130 bites into the fine irregularities of the inner welding surface 14 of the lid 10, and is strongly bonded by an anchoring effect.

[0023] The inner enlarged portion 130 is provided with a planned rupture point 135 that will rupture when the internal pressure of case 2 exceeds the upper pressure limit. The pressure at which the planned rupture point 135 ruptures is the opening pressure of the gas discharge valve 100. The planned rupture point 135 is provided in an annular shape in the region 136 of the inner enlarged portion 130 that corresponds to the inside of the through hole 20. More specifically, the planned rupture point 135 in this embodiment is provided in an annular shape. The center of the annular planned rupture point 135 is provided in line with the central axis of the shaft portion 110. The planned rupture point 135 in this embodiment is a notch shape provided on the side of the inner enlarged portion 130 opposite to the side of the lid 10.

[0024] Figure 3 shows the lid 10 in a state where the planned rupture point 135 has ruptured due to the internal pressure of case 2 reaching the valve opening pressure. When the internal pressure of case 2 rises and the planned rupture point 135 ruptures, the portion of the inner enlargement 130 that is inside the planned rupture point 135 moves outward from case 2. At the same time, the shaft portion 110 connected to the inner portion of the inner enlargement 130, and the outer enlargement 120 connected to the shaft portion 110 also move outward from case 2. As a result, the portion of the inner enlargement 130 that is welded to the lid 10 by the inner weld portion 131 and is outside the planned rupture point 135 remains on the lid 10. As can be seen from Figure 3, when the planned rupture point 135 ruptures, the gas discharge valve 100 opens up, leaving the through hole 20 unblocked. Therefore, the gas inside case 2 can be discharged to the outside of case 2. Therefore, the internal pressure in Case 2 can be reduced.

[0025] As described above, the gas exhaust valve 100 is made of thermoplastic resin. Therefore, deterioration such as corrosion that occurs in metals is suppressed in the gas exhaust valve 100. This suppresses changes in the valve opening pressure. Thus, the valve opening pressure of the gas exhaust valve 100 is maintained over a long period of time. In other words, battery 1 has a highly reliable gas exhaust valve 100.

[0026] Furthermore, in this embodiment, the opening 22 of the through hole 20 on the inside of the case 2 is circular in shape. In addition, the planned fracture point 135 is provided in an annular shape. Therefore, the stress acting on the planned fracture point 135 due to the internal pressure of the case 2 does not vary significantly from one position to the other on the annular planned fracture point 135, but is uniform. In other words, the gas discharge valve 100 is easy to manufacture according to the target opening pressure and has a stable opening pressure. Furthermore, it is preferable that the inner welded portion 131 of the inner enlargement portion 130 is also provided in an annular shape, with its center aligned with the central axis of the shaft portion 110. This makes it possible to further uniformly distribute the stress acting on the planned fracture point 135 due to the internal pressure of the case 2 across the annular planned fracture point 135. That is, the opening pressure of the gas discharge valve 100 can be further stabilized.

[0027] Furthermore, in this embodiment, the through-hole 20 is an injection port for injecting the electrolyte 7 into the case 2. That is, the gas discharge valve 100 is assembled after the case 2 is constructed by assembling the case body 6 and the lid 10, and the electrolyte 7 is injected into the inside of the case 2 through the through-hole 20. The gas discharge valve 100 is then assembled from the outside of the case 2 to the location of the through-hole 20 in the lid 10. Specifically, the inner enlarged portion 130 is inserted into the through-hole 20 from the outside of the through-hole 20, deforming to be smaller than the through-hole 20, and after passing through the through-hole 20, it expands to be larger than the through-hole 20. In the battery 1, the through-hole 20 where the gas discharge valve 100 is located also serves as an injection port. Therefore, the battery 1 does not have a hole used solely for injecting the electrolyte 7, and the shape of the case 2 is simple, so it can be manufactured inexpensively. Also, the rigidity of the case 2 is high due to the fewer holes.

[0028] Furthermore, in this embodiment, the opening 21 on the outer enlarged portion 120 side of the through hole 20 of the lid 10 has a tapered shape that widens towards the outer enlarged portion 120, as shown in Figure 2. In addition, the side of the shaft portion 110 of the gas discharge valve 100 that faces the outer enlarged portion 120 has a tapered shape that is thicker towards the outer enlarged portion 120. The opening 21 of the through hole 20 of the lid 10 and the shaft portion 110 are in contact at their tapered portions. As a result, the center of the planned rupture point 135 is precisely aligned with the central axis of the through hole 20. Therefore, the gas discharge valve 100 receives even pressure from inside the case 2 on the annular planned rupture point 135. Consequently, the gas discharge valve 100 of the battery 1 has an even more stable opening pressure. Moreover, during the manufacturing stage, the gas discharge valve 100 can be easily assembled to the lid 10 while precisely aligning the center of the planned rupture point 135 with the central axis of the through hole 20.

[0029] Furthermore, in this embodiment, the inner enlarged portion 130 has a tapered surface 132 that becomes narrower as it moves away from the shaft portion 110. Moreover, the tapered surface 132 is narrower on the side opposite to the shaft portion 110 than the through hole 20. Figure 2 shows the diameter L1 of the tapered surface 132 on the side opposite to the shaft portion 110 and the diameter L2 of the through hole 20. The diameter L1 of the tapered surface 132 is narrower than the diameter L2 of the through hole 20. As a result, the inner enlarged portion 130 can easily pass through the through hole 20.

[0030] As described above, the battery 1 according to this embodiment comprises a case 2 and a gas discharge valve 100. The case 2 is made of metal, and a through hole 20 is formed in the lid 10, which is one of the wall parts. The gas discharge valve 100 is made of thermoplastic resin and is provided at the location of the through hole 20. The gas discharge valve 100 also has a shaft portion 110, an outer enlargement portion 120, and an inner enlargement portion 130. The shaft portion 110 is located inside the through hole 20. The outer enlargement portion 120 and the inner enlargement portion 130 are provided at the outer and inner ends of the shaft portion 110 of the case 2, respectively. Furthermore, the outer enlargement portion 120 and the inner enlargement portion 130 have a shape that is larger than the through hole 20. The inner enlargement portion 130 is inserted into the through hole 20 from the opening 21 on the side of the outer enlargement portion 120 in the through hole 20, deforming to be smaller than the through hole 20, and after passing through the through hole 20, it is larger than the through hole 20. The inner enlarged portion 130 has an inner welded portion 131 that is welded to the lid 10 in a circle surrounding the through hole 20. Furthermore, the inner enlarged portion 130 is provided with a planned rupture point 135 that will rupture when the internal pressure of the case 2 exceeds the upper pressure limit. The planned rupture point 135 is provided in an annular shape in the region 136 of the inner enlarged portion 130 that corresponds to the inside of the through hole 20. The thermoplastic resin gas discharge valve 100 is less susceptible to deterioration such as corrosion that occurs in metals, thus preventing changes in the valve opening pressure. Therefore, the battery 1 in this embodiment has a highly reliable gas discharge valve 100.

[0031] <Second Embodiment> Next, a second embodiment different from the above embodiment will be described. In the second embodiment, the configuration relating to the gas discharge valve differs from that of the above embodiment. The battery 1 of this embodiment has a gas discharge valve 200, as shown in parentheses in Figure 1. The differences from the above embodiment will be described below.

[0032] Figure 4 is a cross-sectional view relating to this embodiment at position AA shown in Figure 1. Figure 4 shows cross-sections of the lid 10 and the gas exhaust valve 200. In Figure 4, as in Figure 2, the upper side of the lid 10 is on the outside of the case 2, and the lower side of the lid 10 is on the inside of the case 2.

[0033] In this embodiment as well, the gas discharge valve 200 has a shaft portion 110, an outer enlarged portion 120, and an inner enlarged portion 130. The gas discharge valve 200 is also assembled from the outside of the case 2. In other words, the inner enlarged portion 130 is inserted into the through hole 20 from the outside of the through hole 20, deforming to be smaller than the through hole 20, and after passing through the through hole 20, it expands to be larger than the through hole 20.

[0034] In this embodiment, an outer welded portion 121 is formed on the outer enlarged portion 120, which is welded to the lid 10. The outer welded portion 121 is formed on the lid 10 side of the outer enlarged portion 120. Furthermore, the outer welded portion 121 is formed continuously around the through hole 20. Thus, in this embodiment, the outer welded portion 121 and the inner welded portion 131 function as sealing portions that seal the through hole 20 in the case 2.

[0035] The outer welded portion 121 is formed by passing the inner enlarged portion 130 through the through hole 20, followed by a heat treatment that raises the temperature of the area that will become the outer welded portion 121. The outer welded portion 121 can be formed by the same heat treatment as the inner welded portion 131. Furthermore, it is preferable to perform the heat treatment to form the outer welded portion 121 while pressing the outer enlarged portion 120 against the lid 10. This is because it ensures that the outer enlarged portion 120 and the lid 10 are reliably welded together. The outer enlarged portion 120 can be pressed against the lid 10, for example, by pressing the gas discharge valve 200 from the outside of the case 2.

[0036] Furthermore, the outer welded surface 13 on the outer surface 11 of the lid 10 in this embodiment, where the outer welded portion 121 is welded, is rougher than other parts of the outer surface 11. Such an outer welded surface 13 can be provided in the same way as the inner welded surface 14. As a result, the outer welded portion 121 of the outer enlargement 120 is strongly bonded to the outer welded surface 13 of the lid 10 by an anchoring effect.

[0037] In this embodiment, the outer enlarged portion 120 is provided with a fracture point 125 that will rupture when the internal pressure of case 2 exceeds the upper pressure limit. The fracture point 125 is provided in an annular shape in a region 126 corresponding to the area inside the outer welded portion 121 of the outer enlarged portion 120. More specifically, the fracture point 125 in this embodiment is provided in an annular shape. The center of the annular fracture point 125 is aligned with the central axis of the shaft portion 110. The fracture point 125 in this embodiment is a notch shape provided on the side of the outer enlarged portion 120 opposite to the lid 10 side. In this embodiment, the pressure at which both the fracture point 125 of the outer enlarged portion 120 and the fracture point 135 of the inner enlarged portion 130 rupture is the opening pressure of the gas discharge valve 200.

[0038] Figure 5 shows the lid 10 in a state where both the planned rupture point 125 of the outer enlargement 120 and the planned rupture point 135 of the inner enlargement 130 have ruptured due to the internal pressure of case 2 reaching the valve opening pressure. In this embodiment, when the planned rupture points 125 and 135 rupture, the inner portion of the planned rupture point 125 in the outer enlargement 120 and the inner portion of the planned rupture point 135 in the inner enlargement 130 move outwards from case 2. At the same time, the shaft portion 110 connected to the inner portion of the planned rupture point 125 in the outer enlargement 120 and the inner portion of the planned rupture point 135 in the inner enlargement 130 also moves outwards from case 2. As a result, the lid 10 is left with the portion of the outer enlargement 120 that is welded to the lid 10 by the outer weld portion 121 and is outside the planned rupture point 125. Furthermore, the lid 10 will retain the portion of the inner enlargement 130 that is welded to the lid 10 by the inner welded portion 131, which is outside the planned fracture point 135. As can be seen from Figure 5, when both the planned fracture point 125 of the outer enlargement 120 and the planned fracture point 135 of the inner enlargement 130 fracture, the gas discharge valve 200 will be in an open state, not blocking the through hole 20. Therefore, the gas inside the case 2 can be discharged to the outside of the case 2. Consequently, the pressure inside the case 2 can be reduced.

[0039] In this embodiment as well, the gas exhaust valve 200 is made of thermoplastic resin. Therefore, deterioration such as corrosion in metal is suppressed in the gas exhaust valve 200, which prevents changes in the valve opening pressure. Also in this embodiment as well, the inner opening 22 of the through hole 20 is circular in shape. Furthermore, the planned fracture points 125 of the outer enlargement 120 and the planned fracture points 135 of the inner enlargement 130 are provided in an annular shape. Therefore, the gas exhaust valve 200 is also easy to manufacture according to the target valve opening pressure and has a stable valve opening pressure. Furthermore, it is preferable that the outer welded portion 121 of the outer enlargement 120 and the inner welded portion 131 of the inner enlargement 130 are also provided in an annular shape, and that their centers are aligned with the central axis of the shaft portion 110. This makes it possible to further equalize the stress acting on the planned fracture points 125 and 135 due to the internal pressure of the case 2 across the annular planned fracture points 125 and 135. In other words, the opening pressure of the gas discharge valve 200 can be made even more stable. Also, in this embodiment, the through hole 20 is an injection port for injecting the electrolyte 7 into the case 2. Therefore, the battery 1 according to this embodiment also does not have a hole used solely for injecting the electrolyte 7, and the shape of the case 2 is simple, so it can be manufactured at low cost. Also, the rigidity of the case 2 is high due to the fewer holes. Also, in this embodiment, the opening 21 on the outer enlarged portion 120 side of the through hole 20 of the lid 10 has a tapered shape that widens towards the outer enlarged portion 120 side, as shown in Figure 4. Furthermore, the side of the shaft portion 110 of the gas discharge valve 200 that is towards the outer enlarged portion 120 has a tapered shape that is thicker towards the outer enlarged portion 120 side. The opening 21 of the through hole 20 of the lid 10 and the shaft portion 110 are in contact at the tapered portions. Therefore, the gas discharge valve 200 of the battery 1 has an even more stable opening pressure. Furthermore, during the manufacturing process, the central axis of the gas discharge valve 200 can be precisely aligned with the central axis of the through hole 20, and it can be easily assembled to the cover 10. In this embodiment as well, the inner enlarged portion 130 becomes thinner as it moves away from the shaft portion 110, and the side opposite the shaft portion 110 has a tapered surface 132 that is thinner than the through hole 20. This allows the inner enlarged portion 130 to easily pass through the through hole 20.

[0040] Furthermore, in this embodiment of the battery 1, both the outer enlargement portion 120 and the inner enlargement portion 130 of the gas discharge valve 200 are welded to the lid 10. In this configuration, it is preferable that the outer enlargement portion 120 and the inner enlargement portion 130 have different melting points. This is because the outer enlargement portion 120 and the inner enlargement portion 130 can be welded to the lid 10 at different timings. The melting points of the inner enlargement portion 130 and the outer enlargement portion 120 can be achieved by constructing them from thermoplastic resins with different melting points.

[0041] Specifically, for example, the inner enlargement portion 130 can be made of a thermoplastic resin with a higher melting point than the outer enlargement portion 120. When welding is performed in this configuration, first, the area around the through hole 20 of the lid 10 is heated to raise the temperature of the inner enlargement portion 130 to above its melting point. At this time, the temperature of the outer enlargement portion 120, which has a lower melting point than the inner enlargement portion 130, is also raised to above its melting point. In this state, for example, by drawing in the gas exhaust valve 200 from the outside of the case 2, the inner enlargement portion 130 is pressed against the lid 10, while the temperature of the inner enlargement portion 130 is lowered to below its melting point. This forms the inner welded portion 131. After the formation of the inner welded portion 131, with the temperature of the outer enlargement portion 120 above its melting point, the outer enlargement portion 120 is pressed against the lid 10, while the temperature of the outer enlargement portion 120 is lowered to below its melting point, thereby forming the outer welded portion 121. This ensures that both the outer enlargement portion 120 and the inner enlargement portion 130 are reliably welded to the lid 10. The inner enlargement portion 130 can also be made of a thermoplastic resin with a lower melting point than the outer enlargement portion 120. In this case, the outer welded portion 121 can be formed by pressing the outer enlargement portion 120 against the lid 10, and then the inner welded portion 131 can be formed by pressing the inner enlargement portion 130 against the lid 10.

[0042] In this embodiment, as shown in Figure 6, a fire extinguishing agent 210 can be provided between the shaft portion 110 of the gas discharge valve 200 and the wall surface of the through-hole 20 of the cover 10. When the gas discharge valve 200 opens, the battery 1 is likely to be at a high temperature. As shown in Figure 6, the provision of the fire extinguishing agent 210 allows the fire extinguishing agent 210, which was placed in the space inside the through-hole 20, to be injected into the case 2 when the gas discharge valve 200 opens. This allows the fire to be extinguished even if the battery 1 has ignited. In addition, by providing the fire extinguishing agent 210 in the sealed space inside the through-hole 20, it is possible to prevent the fire extinguishing agent 210 from deteriorating due to moisture entering from outside the case 2, for example. In other words, the fire extinguishing agent 210 can be made to function properly.

[0043] In this embodiment, a desiccant 220 can be provided between the shaft portion 110 of the gas exhaust valve 200 and the wall surface of the through-hole 20 of the cover 10, as shown in parentheses in Figure 6. The gas exhaust valve 200, being made of resin, tends to allow moisture to pass through more easily than metal. In the battery 1, it is undesirable for moisture to enter the case 2 from the outside or for the electrolyte 7 to leak out of the case 2. In the battery 1, by providing a desiccant 220 that can absorb moisture and electrolyte 7 in the sealed space inside the through-hole 20, the intrusion of moisture and leakage of electrolyte 7 can be reliably suppressed.

[0044] It is also possible to provide both a fire extinguishing agent 210 and a desiccant 220 in the space inside the through-hole 20. Furthermore, the components of the fire extinguishing agent 210 and the desiccant 220 can be appropriately selected depending on the materials used in the battery 1 and the environment in which the battery 1 is used. Specifically, for example, if the battery 1 is a lithium-ion secondary battery, a fire extinguishing agent 210 with a cooling effect can be selected.

[0045] As described above, the outer enlarged portion 120 of the battery 1 in this embodiment has an outer welded portion 121 that is welded to the lid 10 all around the through hole 20. Furthermore, the outer enlarged portion 120 is provided with a planned rupture point 125 that will rupture when the internal pressure of the case 2 exceeds the upper pressure limit. The planned rupture point 125 is provided in an annular shape in the region 126 of the outer enlarged portion 120 that is inside the outer welded portion 121. Furthermore, the inner enlarged portion 130 is provided with a planned rupture point 135 that will rupture when the internal pressure of the case 2 exceeds the upper pressure limit. The planned rupture point 135 is provided in an annular shape in the region 136 of the inner enlarged portion 130 that corresponds to the inside of the through hole 20. The thermoplastic resin gas discharge valve 200 is designed to suppress deterioration such as corrosion in metals, thereby preventing changes in the valve opening pressure. Therefore, the battery 1 in this embodiment has a highly reliable gas discharge valve 200.

[0046] Furthermore, the gas discharge valve 200 may have an outer welded portion 121 formed only on the outer enlarged portion 120, and no welded portion formed with the lid 10 on the inner enlarged portion 130. Even if the gas discharge valve 200 is configured with only the outer enlarged portion 120 welded, the outer welded portion 121 can form a sealing portion that seals the through hole 20 in the case 2. In addition, when the pressure inside the case 2 reaches the valve opening pressure, the planned rupture point 125 of the outer enlarged portion 120 and the planned rupture point 135 of the inner enlarged portion 130 will rupture, allowing the gas discharge valve 200 to open properly.

[0047] The embodiments described above 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.

[0048] For example, in the above embodiment, when assembling the gas exhaust valve to the through-hole of the lid, an example was described in which the gas exhaust valve was installed from the outside of the case by passing the inner enlargement portion through the through-hole. However, before assembling the case body and the lid, it is also possible to assemble the gas exhaust valve to the through-hole of the lid by passing the outer enlargement portion through the through-hole. That is, one of the outer and inner enlargements of the gas exhaust valve, the one enlargement portion, should be inserted into the through-hole from the opening on the other side of the through-hole, which is different from the one enlargement portion, while deforming to be smaller than the through-hole. Furthermore, after passing through the through-hole, the one enlargement portion should expand to be larger than the through-hole. Note that when installing the gas exhaust valve to the through-hole of the case after the assembly of the lid and the case body is completed, it is preferable to pass the inner enlargement portion through the through-hole from the outside of the case. Furthermore, if a configuration is adopted in which tapered shapes are provided on the opening of the through-hole in the lid and the shaft of the gas discharge valve, and these tapered shapes are brought into contact with each other to align the central axes, then tapered shapes should be provided on the opening on the other enlarged side of the through-hole and on the other enlarged side of the shaft. In addition, by providing a tapered shape on one enlarged section that becomes thinner as it moves away from the shaft, it is possible to easily pass the one enlarged section through the through-hole.

[0049] Furthermore, for example, the specific location and shape of the planned rupture point in the gas discharge valve described in the above embodiment are merely examples and can be changed as appropriate. Also, for example, the gas discharge valve is not limited to the lid but can be provided on other walls that make up the case. Also, for example, the application of the above embodiment is not particularly limited in terms of battery type (types such as nickel-metal hydride batteries and lithium-ion batteries). In addition, the technology disclosed in the above embodiment can be realized in various forms, such as battery manufacturing methods.

[0050] Furthermore, the disclosed technology described above includes the following means 1 to means 10. [Means 1] A metal case with through holes formed in the wall, The system includes a gas discharge valve made of thermoplastic resin, which is provided at the location of the through-hole. The aforementioned gas discharge valve is The shaft portion located inside the through hole, The shaft portion is provided at the outer and inner ends of the case, respectively, and has an outer enlarged portion and an inner enlarged portion that are larger than the through hole, One of the outer and inner enlarged portions, the one enlarged portion, is inserted into the through-hole from the opening on the other side of the through-hole, which is different from the one enlarged portion, deforming to be smaller than the through-hole, and after passing through the through-hole, it expands to be larger than the through-hole. The enlarged inner portion has an inner welded portion formed around the through hole, which is welded to the case. The aforementioned enlarged inner portion of the battery has a pre-emptive rupture point, which is provided in an annular shape in the region corresponding to the inside of the through-hole, where the battery will rupture when the internal pressure of the case exceeds a predetermined upper pressure limit.

[0051] [Means 2] A metal case with through holes formed in the wall, The system includes a gas discharge valve made of thermoplastic resin, which is provided at the location of the through-hole. The aforementioned gas discharge valve is The shaft portion located inside the through hole, The shaft portion is provided at the outer and inner ends of the case, respectively, and has an outer enlarged portion and an inner enlarged portion that are larger than the through hole, One of the outer and inner enlarged portions, the one enlarged portion, is inserted into the through-hole from the opening on the other side of the through-hole, which is different from the one enlarged portion, deforming to be smaller than the through-hole, and after passing through the through-hole, it expands to be larger than the through-hole. The outer enlarged portion has an outer welded portion formed around the through hole, which is welded to the case. The outer enlarged portion has a fracture point, which is provided in an annular shape in a region inside the outer welded portion, where the case will rupture when the internal pressure exceeds a predetermined upper pressure limit. The battery is provided in the enlarged inner portion in an annular shape in the region corresponding to the inside of the through hole where the planned fracture point is located.

[0052] [Means 3] The battery described in method 2, The aforementioned gas discharge valve is The battery has an inner welded portion formed around the inner enlargement portion, which is welded to the case so as to surround the through hole.

[0053] [Means 4] The battery described in means 3, A battery in which a fire extinguishing agent is provided between the shaft portion and the wall surface of the through hole.

[0054] [Means 5] A battery according to means 3 or means 4, A battery in which a desiccant is provided between the shaft portion and the wall surface of the through hole.

[0055] [Means 6] A battery according to any of means 3 to means 5, The outer enlarged portion and the inner enlarged portion are batteries with different melting points.

[0056] [Means 7] A battery according to any of the means 1 to means 6, The opening of the aforementioned through hole is circular in shape. The aforementioned point of failure is a battery arranged in a ring shape.

[0057] [Means 8] A battery according to any of the means 1 to means 7, The case contains an electrolyte solution, The through-hole is a battery, which is a liquid injection port for injecting the electrolyte into the case.

[0058] [Means 9] A battery according to any of the means 1 to means 8, The opening of the through hole on the other enlarged portion side has a tapered shape that widens towards the other enlarged portion side. The other enlarged portion of the shaft has a tapered shape, becoming thicker towards the other enlarged portion. A battery in which the opening on the other enlarged side of the through hole and the shaft portion are in contact at tapered portions.

[0059] [Means 10] A battery according to any of the means 1 to means 9, The aforementioned enlarged portion has a tapered surface that becomes thinner as it moves away from the shaft portion. The tapered surface is a battery in which the size on the side opposite to the shaft portion is smaller than the through hole. [Explanation of Symbols]

[0060] 1:Battery 2: Case 7: Electrolyte 10: Lid 13:Outer welding surface 14:Inner welding surface 20: Through hole 22: Opening 100, 200: Gas exhaust valve 110: Shaft 120: External expansion part 121:Outside welding part 125, 135: Expected fracture points 130: Enlarged inner section 131:Inner weld part 132: Tapered surface 136 :Area 210: Fire extinguishing agent 220: Desiccant

Claims

1. A metal case with through holes formed in the wall, The system includes a gas discharge valve made of thermoplastic resin, which is provided at the location of the through-hole. The aforementioned gas discharge valve is The shaft portion located inside the through hole, The shaft portion is provided at the outer and inner ends of the case, respectively, and has an outer enlarged portion and an inner enlarged portion that are larger than the through hole, One of the outer and inner enlarged portions, the one enlarged portion, is inserted into the through hole from the opening on the other side of the through hole, which is different from the one enlarged portion, deforming to be smaller than the through hole, and after passing through the through hole, it expands to be larger than the through hole. The enlarged inner portion has an inner welded portion formed around the through hole, which is welded to the case. The aforementioned enlarged inner portion of the battery has a planned rupture point, which is provided in an annular shape in the region corresponding to the inside of the through hole, where the battery will rupture when the internal pressure of the case exceeds a predetermined upper pressure limit.

2. A metal case with through holes formed in the wall, The system includes a gas discharge valve made of thermoplastic resin, which is provided at the location of the through-hole. The aforementioned gas discharge valve is The shaft portion located inside the through hole, The shaft portion is provided at the outer and inner ends of the case, respectively, and has an outer enlarged portion and an inner enlarged portion that are larger than the through hole, One of the outer and inner enlarged portions, the one enlarged portion, is inserted into the through hole from the opening on the other side of the through hole, which is different from the one enlarged portion, deforming to be smaller than the through hole, and after passing through the through hole, it expands to be larger than the through hole. The outer enlarged portion has an outer welded portion formed around the through hole, which is welded to the case. The outer enlarged portion has a fracture point, which is provided in an annular shape in a region inside the outer welded portion, where the case will rupture when the internal pressure exceeds a predetermined upper pressure limit. The battery is provided in the enlarged inner portion in an annular shape in the region corresponding to the inside of the through hole where the planned fracture point is located.

3. The battery according to claim 2, The aforementioned gas discharge valve is The battery has an inner welded portion formed around the inner enlargement portion, which is welded to the case so as to surround the through hole.

4. A battery according to any one of claims 1 to 3, The opening of the aforementioned through hole is circular in shape. The aforementioned point of failure is a battery arranged in a ring shape.

5. A battery according to any one of claims 1 to 3, The case contains an electrolyte solution, The through-hole is a battery, which is a liquid injection port for injecting the electrolyte into the case.

6. A battery according to any one of claims 1 to 3, The opening of the through hole on the other enlarged portion side has a tapered shape that widens towards the other enlarged portion side. The other enlarged portion of the shaft has a tapered shape, becoming thicker towards the other enlarged portion. A battery in which the opening on the other enlarged side of the through hole and the shaft portion are in contact at tapered portions.

7. The battery according to claim 3, A battery in which a fire extinguishing agent is provided between the shaft portion and the wall surface of the through hole.

8. The battery according to claim 3, A battery in which a desiccant is provided between the shaft portion and the wall surface of the through hole.

9. The battery according to claim 3, The outer enlarged portion and the inner enlarged portion are batteries with different melting points.

10. A battery according to any one of claims 1 to 3, The aforementioned enlarged portion has a tapered surface that becomes thinner as it moves away from the shaft portion. The tapered surface is a battery in which the size on the side opposite to the shaft portion is smaller than the through hole.

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