Secondary battery

Abstract

The utility model provides a secondary battery capable of inhibiting electrolyte permeation or moisture invasion. The secondary battery is provided with a case main body part (11) forming the surface of a battery cell and a gas discharge valve (12) arranged on the case main body part (11), the gas discharge valve (12) is provided with movable parts (31, 32) capable of moving in the inner direction and the outer direction, and the movable parts (31, 32) move in the inner direction and open when a specified external force is applied. As a result, the gas discharge valve (12) can be closed in advance even in a state in which the internal pressure increases, and the gas discharge valve (12) can be opened by an external force.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a secondary battery. BACKGROUND

[0002] In recent years, a secondary battery is utilized in traveling of a vehicle or the like. In Patent Document 1, a safety valve is described, which performs opening and closing operation based on a prescribed safety valve pressure when a pressure inside a secondary battery changes. More specifically, in the secondary battery, when the internal pressure rises due to repeated charging and discharging, the safety valve can be opened to discharge internal gas, and in a case where the internal pressure becomes a prescribed internal pressure lower than the internal pressure at the time of initial charging, the safety valve can be closed.

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2002-192161

[0004] However, in the secondary battery disclosed in Patent Document 1, since the valve is opened and closed in accordance with the internal pressure, electrolyte permeation or the like is likely to occur during a period until the internal pressure decreases. More specifically, in a configuration in which a check valve whose internal pressure reaches a prescribed pressure is used in the secondary battery, a spring load that attempts to close the valve and a load generated by the interaction of the internal pressure that attempts to open the valve and a pressure receiving area are in opposite directions. In the secondary battery of this configuration, as the internal pressure rises, the seal member pressing load gradually decreases, and thus there is a problem that electrolyte permeation or moisture intrusion from the outside is likely to occur during a period until the internal pressure decreases. SUMMARY

[0005] The present disclosure provides a secondary battery in which electrolyte permeation or moisture intrusion is suppressed.

[0006] The secondary battery according to the present disclosure has a housing main body portion that forms a surface of a battery cell, and a gas discharge valve provided to the housing main body portion, the gas discharge valve having a movable member that is capable of operating in an inside direction and an outside direction, and by applying a prescribed external force, the movable member moves in the inside direction to open the valve.

[0007] Thus, even in a state where the internal pressure rises, the gas discharge valve can be closed in advance, and the gas discharge valve can be opened by the external force.

[0008] According to the present disclosure, it is possible to provide a secondary battery in which electrolyte permeation or moisture intrusion is suppressed. BRIEF DESCRIPTION OF DRAWINGS

[0009] FIG. 1A and FIG. 1B is a schematic enlarged view of a cross section in the vicinity of a surface of a battery cell of the secondary battery according to Embodiment 1.

[0010] FIG. 2A to FIG. 2Cis a schematic view showing a modification of the environment around the secondary battery according to Embodiment 1.

[0011] FIG. 3A and FIG. 3B is a schematic enlarged view of a cross section of the vicinity of the surface of the battery cell whose constitution is modified in the secondary battery according to Embodiment 2. DETAILED DESCRIPTION

[0012] A secondary battery according to Embodiment 1 will be described below with reference to the drawings. FIG. 1A and FIG. 1B is a view showing a gas discharge valve and its vicinity provided in a battery cell 1 of a secondary battery. More specifically, FIG. 1A and FIG. 1B is a schematic cross-sectional view of the vicinity of the surface of the battery cell 1, and is a schematic enlarged view of the surface of the battery cell 1 on which the gas discharge valve 12 is provided facing upward. In addition, FIG. 1A is a state in which the gas discharge valve 12 described later is closed, FIG. 1B shows a state in which the gas discharge valve 12 is open. Also, in the following FIG. 1A , FIG. 1B and the like, the hatching is omitted in the cross-sectional views in order to easily determine the parts.

[0013] The battery cell 1 has a case main body portion 11 that forms a surface of the battery cell 1, and a gas discharge valve 12 provided to the case main body portion 11.

[0014] The case main body portion 11 has a surface portion 21 and a protruding portion 22 that protrudes upward from the surface portion 21.

[0015] The surface portion 21 is a surface of the case main body portion 11. As FIG. 1A shown, it is assumed here that the surface portion 21 is disposed upward of the battery cell 1 and is a face that occupies a large portion of the case main body portion 11, and will be described. In addition, the inside of the battery cell 1 is on the lower side than the surface portion 21, and the outside of the secondary battery is on the upper side than the surface portion 21. In addition, the inside of the battery cell 1 is set as an inside face 21a in the surface portion 21. In addition, the inside of the battery cell 1 is described on the inside than the surface portion 21 and on the inside than the protruding portion 22.

[0016] The protruding portion 22 is a site that protrudes from the surface portion 21 toward the outside, that is, upward. For example, the protruding portion 22 has an upper surface portion 22a that is an upper surface of the protruding portion 22 and a side face portion 22b that is a wall face, the upper surface portion 22a extends in the horizontal direction, and the side face portion 22b extends in the up-down direction between the upper surface portion 22a and the surface portion 21. A through hole 22c that penetrates in the up-down direction is provided in the upper surface portion 22a.

[0017] Further, the protruding portion 22 has a housing portion 22d, which is a space surrounded by the side portion 22b and provided below the upper surface portion 22a. In the housing portion 22d, a shaft 31 of a gas discharge valve 12 described later extends in the vertical direction, and a tension spring 33 is housed. Further, as described later, a part of the upper portion side of the shaft 31 is provided through a through-hole 22c provided on the upper surface portion 22a, which is the upper surface of the housing portion 22d, and protrudes upward.

[0018] Here, as shown in FIG. 1A the side portion 22b of the protruding portion 22 is provided so as to extend in the vertical direction. In other words, the length in the left-right direction at any position in the housing portion 22d is substantially the same.

[0019] Further, a part of the lower portion side of the housing portion 22d, which is open in the inner side direction of the battery cell 1, is provided as an opening portion 22e. As described in detail later, the opening portion 22e is switched between a state in which it is occluded by the gas discharge valve 12 and a state in which it is not occluded.

[0020] The gas discharge valve 12 has the shaft 31 extending in the vertical direction, a pressure receiving portion 32 provided at the tip of the shaft 31, and the tension spring 33 provided in a spiral shape around the shaft 31. Here, the shaft 31 and the pressure receiving portion 32 are movable members and can act in the inner side direction and the outer side direction as described later.

[0021] The shaft 31 extends in the vertical direction inside the housing portion 22d provided in the protruding portion 22, and a part of the upper portion side is provided through the through-hole 22c of the upper surface portion 22a. Further, there is a gap between the shaft 31 and the through-hole 22c through which gas can pass.

[0022] Further, at the upper portion of the shaft 31, a power source that causes the shaft 31 to act in the downward direction is connected to the outside of the housing main portion 11. Further, the lower end portion of the shaft 31 is connected to the upper surface of the pressure receiving portion 32.

[0023] Here, the power source connected to the upper portion of the shaft 31 is a publicly known solenoid actuator or the like, but is not limited thereto.

[0024] The pressure receiving portion 32 is thin in the vertical direction and is in the form of a plate, and the length in the left-right direction is greater than the length in the vertical direction. That is, the pressure receiving portion 32 is a plate having flat surfaces in the vertical direction, and the upper surface 32a is in the outer side direction of the battery cell 1, and the lower surface 32b is in the inner side direction of the battery cell 1.

[0025] The lower end of the shaft 31 is connected to the central portion in the left-right direction on the upper surface 32a of the pressure receiving portion 32. Further, the length in the left-right direction of the pressure receiving portion 32 is longer than the length in the left-right direction of the protruding portion 22.

[0026] Further, the lower surface 32b of the pressure receiving portion 32 receives a force in the upward direction due to the internal pressure generated on the inside of the battery cell 1 (in FIG. 1A and FIG. 1B , the lower black arrow indicates the direction of the internal pressure). At this time, the upper surface 32a of the pressure receiving portion 32 near the end portions in the left and right directions is pressed in the upward direction in a state of abutting against the inside surface 21a of the surface portion 21. In other words, the pressure receiving surface of the lower surface 32b of the pressure receiving portion 32 is subjected to the internal pressure, and functions as a sealing load of the opening portion 22e of the lower portion of the occlusion housing portion 22d.

[0027] The tension spring 33 is a spring provided in a spiral shape around the rod 31 in a state of centering on the rod 31. The upper end portion of the tension spring 33 is connected to the lower surface of the upper surface portion 22a of the protruding portion 22, and the lower end portion of the tension spring 33 is connected to the upper surface 32a of the pressure receiving portion 32. The tension spring 33 generates a force in a direction in which the upper surface portion 22a of the protruding portion 22 is brought close to the pressure receiving portion 32. Further, since the upper surface portion 22a of the protruding portion 22 is fixed, substantially, the tension spring 33 generates a force in the upward direction (in FIG. 1A and FIG. 1B , the white arrow indicates the direction of the spring force) with respect to the pressure receiving portion 32.

[0028] According to the above structure, in the pressure receiving portion 32, a force in the upward direction due to the internal pressure of the battery cell 1 acts on the lower surface 32b, and becomes a state of being stretched in the upward direction by the tension spring 33. Therefore, in the battery cell 1, the opening portion 22e of the housing portion 22d can be occluded by the two forces in the outside direction.

[0029] On the other hand, in a case where a force in the downward direction (in FIG. 1B , the upper black arrow indicates the direction of the force from the outside) is applied to the rod 31 by the power from the power source connected to the upper portion of the rod 31, the force in the downward direction becomes stronger than the force in the upward direction applied to the pressure receiving portion 32, and as shown in FIG. 1B , a state in which the upper surface 32a of the pressure receiving portion 32 is separated from the inside surface 21a of the surface portion 21 is generated. In other words, the force in the inside direction becomes stronger than the force in the outside direction applied to the movable member in the gas discharge valve 12. Thereby, a gap is generated between the upper surface 32a of the pressure receiving portion 32 and the inside surface 21a of the surface portion 21, and the gas can pass between the inside of the battery cell 1 and the housing portion 22d.

[0030] Further, in the battery cell 1, a gap through which gas can pass is provided between the rod 31 and the through-hole 22c. Therefore, in the battery cell 1, gas that moves from the inside of the battery cell 1 to the accommodation portion 22d passes through the gap between the rod 31 and the through-hole 22c and is discharged to the outside.

[0031] Thus, in the battery cell 1, the gas discharge valve 12 can be opened by applying an inward force caused by an external force to the movable member of the gas discharge valve 12. Here, in the battery cell 1, even if the internal pressure rises, the state in which the gas discharge valve 12 is closed can be maintained, and thus the penetration of electrolyte and the like can be suppressed.

[0032] Further, in the battery cell 1, FIG. 2A is a view showing an example in which, in a case where a plurality of battery cells 2 are provided in the lower portion of the vehicle body, each of the cells is connected by a pipe, and a gas discharge valve 12 is provided in the front of the pipe. By thus providing the gas discharge valve 12 in the front of the pipe to which a plurality of battery cells are connected, it is not necessary to provide the gas discharge valve 12 in each of the plurality of battery cells 2. That is, it is only necessary to provide one gas discharge valve 12 in one battery pack in which a plurality of battery cells 2 are accommodated, and thus the cost can be reduced.

[0033] Further, in the battery cell 1, FIG. 2B is an example of a battery cell 3 in which a gas bag 41 for preliminarily holding gas so as not to be discharged to the outside of the vehicle is provided in a case where the gas is discharged from the inside of the battery cell 1 to the outside. Thus, in the vehicle body, a configuration in which the gas discharged from the secondary battery is sealed can be obtained.

[0034] Further, if the amount of gas discharged from the secondary battery is small, the gas can be allowed to be released to the atmosphere. Here, FIG. 2C is a view showing a state of a battery cell 3 in which, in a case where the gas is released to the atmosphere, a secondary battery is covered with another housing, and a semi-permeable membrane 42 is provided, in order to prevent moisture from entering.

[0035] Further, as shown in FIG. 2B and FIG. 2C , in the secondary battery, a signal or power can be supplied to a coil 43 disposed around the rod by a signal line 44, and a downward force can be generated with respect to the rod. Further, as shown in FIG. 2B , FIG. 2C , the size of the gas bag 41 can be arbitrarily changed.

[0036] FIG. 3A is a view showing an example of a configuration of a battery cell 4 of a secondary battery according to Embodiment 2. In the battery cell 4, a housing main portion 51, a gas discharge valve 52, and a wall portion 53 are provided.

[0037] The case main body portion 51 has a surface portion 61 and a through-hole 62 that penetrates the surface portion 61 in the up-down direction.

[0038] The gas discharge valve 52 has a rod 71 that extends in the up-down direction, a pressure receiving portion 72 that is connected to the tip of the rod 71, and a compression spring 73 that is installed to the lower side of the pressure receiving portion 72. In addition, the rod 71 is disposed so as to penetrate the through-hole 62.

[0039] The wall surface portion 53 is formed on the inner side than the case main body portion 51. The wall surface portion 53 is formed with a protruding portion 81 that protrudes in the inner side direction of the battery cell 4. Here, the protruding portion 81 has a lower surface portion 81a, a side surface portion 81b, a through-hole 81c that is formed in the lower surface portion 81a, and a housing portion 81d that is formed by the lower surface portion 81a and the side surface portion 81b being surrounded. The pressure receiving portion 72 and the compression spring 73 of the gas discharge valve 52 are housed in the housing portion 81d.

[0040] Here, the upper end portion of the compression spring 73 is connected to the lower surface of the pressure receiving portion 72, and the lower end portion of the compression spring 73 is connected to the upper side of the lower surface portion 81a of the protruding portion 81 in the wall surface portion 53. Due to this, the compression spring 73 is able to generate a force that presses the pressure receiving portion 72 in the upward direction.

[0041] On the other hand, the pressure receiving portion 72 is pressed in the upward direction by the internal pressure of the battery cell 4. Due to this, the pressure receiving portion 72 is able to cause the through-hole 62 of the surface portion 61 to be occluded by the spring force of the compression spring 73 (in FIG. 3A Here, the intermediate white solid line arrow indicates the direction of the spring force, and the lower black arrow indicates the direction of the internal pressure) and the force in the upward direction from the internal pressure inside the battery cell, and is able to cause the through-hole 62 of the surface portion 61 to be occluded.

[0042] Here, the shape of the housing portion 81d is roughly the same as the shape of the pressure receiving portion 72. Due to this, even in the case where the pressure receiving portion 72 moves up and down, even in the state where it is disposed at the upper dead point, it is able to cause the through-hole 62 to be occluded without shifting in the left-right direction.

[0043] In addition, as with Embodiment 1, in the battery cell 4, in the case where an external force that is applied in the downward direction (in FIG. 3A Here, the upper dashed line arrow indicates the direction of the force from the outside that is applied, and the lower dashed line arrow indicates the direction of the force from the internal pressure of the battery cell) is applied to the upper portion of the rod 71, and this force exceeds the spring force of the compression spring 73 that is applied to the pressure receiving portion 72 and the force based on the internal pressure of the battery cell, the pressure receiving portion 72 moves in the downward direction. Due to this, it is able to discharge gas from the gap between the through-hole 62 and the rod 71.

[0044] As a simpler embodiment, it is possible to adopt a configuration in which gas is manually discharged in a secondary battery. FIG. 3B is an example of a configuration in which gas is manually discharged.

[0045] More specifically, it becomes a state in which the upper end portion of the rod 31 of the battery cell 1 shown in Embodiment 1 protrudes to the outside from the battery pack in which the battery cell 1 is housed. Thereby, even in the vehicle-mounted state, it becomes a state in which a part of the valve is disposed at a position accessible by a person, and the gas discharge work can be performed at an automobile dealer or the like.

[0046] In addition, even in this case, by providing the semi-permeable membrane 91 outside the battery pack and in the vicinity of the upper end portion of the rod 31 or the like, the inside and outside of the battery pack are divided, and the intrusion of moisture into the battery cell 1 or the like can be suppressed.

[0047] As an application in this case, the gas discharge timing can be calculated from the history information of the discharge of the vehicle, the user is notified of the gas discharge timing by an information display or the like mounted on the vehicle, and the user is encouraged to go to the automobile dealer. Or, as a mechanism for notifying the vehicle manufacturer of the gas discharge timing information calculated in this way, the vehicle manufacturer can send a notification that the target vehicle is the gas discharge timing to the automobile dealer, and the user is encouraged to go to the automobile dealer.

[0048] In addition, the present application is not limited to the above-described embodiments, and can be appropriately changed within the scope of the gist. That is, the above description is appropriately omitted and simplified for the sake of clarification of explanation, and as long as a person skilled in the art, each element of the embodiments can be changed, added, or transformed within the scope of the present application.

Claims

1. A secondary battery characterized by comprising: Having: a case main body portion that forms a surface of a battery cell; and a gas discharge valve provided to the case main body portion, the gas discharge valve has a movable member that can act in an inside direction and an outside direction, by applying a prescribed external force, the movable member moves in the inside direction to open the valve.

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