Secondary battery

Abstract

To provide a secondary battery in which permeation of an electrolyte and intrusion of moisture are suppressed.SOLUTION: A secondary battery includes a case body unit 11 forming a surface of a battery cell and a gas discharge valve 12 provided in the case body unit 11. The gas discharge valve 12 has movable members 31, 32 operable in an inward direction and an outward direction, and the movable members 31, 32 are moved in an inward direction by applying predetermined external force to open the valve. As a result, the gas discharge valve 12 can be closed even in a state where internal pressure is increased, and the gas discharge valve can be opened by external force.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to secondary batteries.

Background Art

[0002] In recent years, secondary batteries have been used in vehicle driving and the like. Patent Document 1 describes a safety valve that opens and closes based on a predetermined safety valve pressure when the internal pressure of a secondary battery changes. More specifically, in this secondary battery, when the internal pressure increases due to repeated charge and discharge, the safety valve opens to discharge the internal gas, and when the internal pressure reaches a predetermined internal pressure lower than the internal pressure at the initial charge, the safety valve can be closed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the secondary battery disclosed in Patent Document 1, since the valve opens and closes according to the internal pressure, electrolyte permeation and the like are likely to occur before the internal pressure decreases. More specifically, in a secondary battery having a structure using a check valve in which the internal pressure reaches a predetermined pressure, the spring load for closing the valve and the load obtained by multiplying the internal pressure for opening the valve by the pressure receiving area are in opposite directions. In a secondary battery having this structure, since the seal pressing load gradually decreases as the internal pressure increases, there is also a problem that there is a concern about electrolyte permeation and moisture intrusion from the outside before the internal pressure decreases.

[0005] The present disclosure provides a secondary battery that suppresses the occurrence of electrolyte permeation and moisture intrusion.

Means for Solving the Problems

[0006] The secondary battery according to the present disclosure includes a case main body portion that forms the surface of a battery cell, and a gas discharge valve provided on the case main body portion. The gas discharge valve has a movable member that is operable in an inner direction and an outer direction, and the movable member moves in the inner direction by applying a predetermined external force to open the valve. Thereby, even when the internal pressure rises, the gas discharge valve can be closed, and the gas discharge valve can be opened by an external force.

Advantages of the Invention

[0007] According to the present disclosure, it is possible to provide a secondary battery that can suppress the permeation of an electrolytic solution and the occurrence of moisture intrusion.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0009] Embodiment 1 Hereinafter, a secondary battery according to the present embodiment will be described with reference to the drawings. FIGS. 1(a) and 1(b) are diagrams showing a gas discharge valve provided in a battery cell 1 of a secondary battery and the vicinity thereof. More specifically, FIGS. 1(a) and 1(b) are cross-sectional views near the surface of the battery cell 1, and are enlarged views with the surface on which the gas discharge valve 12 is provided facing upward. Note that FIG. 1(a) shows a state in which the gas discharge valve 12 described later is closed, and FIG. 1(b) shows a state in which the gas discharge valve 12 is open. In the following, in cross-sectional views such as FIGS. 1(a) and 1(b), the description of hatching is omitted for easy understanding of each part.

[0010] The battery cell 1 includes a case main body portion 11 that forms the surface of the battery cell 1 and a gas discharge valve 12 provided on the case main body portion 11.

[0011] The case main body portion 11 includes a surface portion 21 and a protruding portion 22 that protrudes upward from the surface portion 21.

[0012] The surface portion 21 is the surface of the case main body portion 11. As shown in Fig. 1(a), here, the surface portion 21 is arranged above the battery cell 1 and will be described as a surface that occupies most of the case main body portion 11. Note that the lower part of the surface portion 21 is the inside of the battery cell 1, and the upper part of the surface portion 21 is the outside of the secondary battery. Here, the inner side of this surface portion 21 is defined as the inner surface 21a. Also, as shown in Fig. 1(a), the vertical direction may be described as the Z direction, the horizontal direction as the X direction, and the depth direction as the Y direction. Also, the inside of the surface portion 21 and inside the protruding portion 22 will be described as the inside of the battery cell 1.

[0013] The protruding portion 22 is a portion that protrudes upward from the surface portion 21 toward the outside. For example, the protruding portion 22 has an upper surface portion 22a that extends horizontally on the upper surface of the protruding portion 22 and a side surface portion 22b that is a wall surface extending in the vertical direction between the upper surface portion 22a and the surface portion 21. A through hole 22c that penetrates in the vertical direction is provided in the upper surface portion 22a.

[0014] Furthermore, the protruding portion 22 has a storage portion 22d that is surrounded by the side surface portion 22b and is provided below the upper surface portion 22a. In the storage portion 22d, a rod 31 of the gas discharge valve 12 described later extends in the vertical direction, and a tension spring 33 is stored. As will be described later, a part of the upper side of the rod 31 penetrates through the through hole 22c provided in the upper surface portion 22a, which is the upper surface of the storage portion 22d, and protrudes upward.

[0015] Here, as shown in Fig. 1(a), it is assumed that the side surface portion 22b of the protruding portion 22 is provided to extend in the vertical direction. In other words, it will be described that the length in the XY direction at any position in the storage portion 22d is substantially the same.

[0016] Note that an opening 22e is provided at the lower side of the storage portion 22d and opens in the inner direction of the battery cell 1. As will be described in detail later, the opening 22e switches between a state of being blocked by the gas discharge valve 12 and a state of not being blocked.

[0017] The gas discharge valve 12 includes a rod 31 extending in the vertical direction, a pressure receiving portion 32 provided at the tip of the rod 31, and a tension spring 33 provided in a spiral shape around the rod 31. Here, the rod 31 and the pressure receiving portion 32 are movable members and can operate in the inner direction and the outer direction as will be described later.

[0018] The rod 31 extends in the vertical direction within the storage portion 22d provided in the protruding portion 22, and a part of the upper side thereof passes through a through hole 22c provided in the upper surface portion 22a. There is a gap through which gas can pass between the rod 31 and the through hole 22c.

[0019] Furthermore, a power source for operating the rod 31 downward is connected to the upper part of the rod 31 outside the case main body portion 11. Also, the lower end portion of the rod 31 is connected to the upper surface of the pressure receiving portion 32.

[0020] Here, the power source connected to the upper part of the rod 31 is a known solenoid actuator or the like, but is not limited thereto.

[0021] The pressure receiving portion 32 is formed thin in the Z direction and has a plate surface shape that is longer in the XY direction than in the Z direction. That is, the pressure receiving portion 32 is a plate having planes on the top and bottom, the upper surface 32a is arranged in the outer direction of the battery cell 1, and the lower surface 32b is arranged in the inner direction of the battery cell 1.

[0022] The lower end of the rod 31 is connected to the central portion in the XY direction of the upper surface 32a of the pressure receiving portion 32. Also, the length of the pressure receiving portion 32 in the XY direction is longer than the length of the protruding portion 22 in the XY direction, respectively.

[0023] Also, the lower surface 32b of the pressure receiving portion 32 receives an upward force due to the internal pressure generated inside the battery cell 1. At this time, the upper surface 32a near the end portion in the XY direction of the pressure receiving portion 32 is pressed upward while being in contact with the inner surface 21a of the surface portion 21. In other words, an internal pressure is applied to the pressure receiving surface of the surface of the lower surface 32b of the pressure receiving portion 32, and it acts as a sealing load for closing the opening 22e corresponding to the lower portion of the storage portion 22d.

[0024] The tension spring 33 is a spring provided in a spiral shape around the rod 31 in a state centered 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 of the pressure receiving portion 32. The tension spring 33 generates a force in a direction to bring the upper surface portion 22a of the protruding portion 22 and the pressure receiving portion 32 closer to each other. Since the upper surface portion 22a of the protruding portion 22 is fixed, substantially, the tension spring 33 generates an upward pulling force on the pressure receiving portion 32.

[0025] With the above configuration, in the pressure receiving portion 32, an upward force acts on the lower surface 32b due to the internal pressure of the battery cell 1, and it is in a state of being pulled upward by the tension spring 33. Therefore, in the battery cell 1, the opening 22e of the storage portion 22d can be closed by these two outward forces.

[0026] On the other hand, when a downward force is applied to the rod 31 by the power from the power source connected to the upper portion of the rod 31 and the downward force becomes stronger than the upward force applied to the pressure receiving portion 32, as shown in Fig. 1(b), the upper surface 32a of the pressure receiving portion 32 is separated from the inner surface 21a of the surface portion 21. In other words, the inward force becomes stronger than the outward force applied to the movable member in the gas discharge valve 12. As a result, a gap is generated between the upper surface 32a of the pressure receiving portion 32 and the inner surface 21a of the surface portion 21, and gas can pass between the inside of the battery cell 1 and the storage portion 22d.

[0027] Furthermore, in the battery cell 1, there is a gap through which gas can pass between the rod 31 and the through-hole 22c. Therefore, in the battery cell 1, a gap is formed between the upper surface 32a of the pressure-receiving portion 32 and the inner surface 21a of the surface portion 21, and the gas that has moved from the inside of the battery cell 1 to the storage portion 22d escapes through the gap between the rod 31 and the through-hole 22c and is discharged to the outside.

[0028] In this way, in the battery cell 1, the gas discharge valve 12 can be opened by applying an inward force due to an external force to the movable member of the gas discharge valve 12. Here, in the battery cell 1, even when the internal pressure rises, the gas discharge valve 12 can be maintained in a closed state, so that the permeation of the electrolytic solution can be suppressed.

[0029] Note that Fig. 2(a) shows an example in which a plurality of battery cells 2 are provided in the lower part of the vehicle body, each cell is connected by a conduit, and a gas discharge valve 12 is provided at the tip of the conduit. By providing the gas discharge valve 12 at the tip of the conduit connecting the plurality of battery cells in this way, it is not necessary to provide a gas discharge valve 12 for each of the plurality of battery cells 2. That is, since it is only necessary to provide one gas discharge valve 12 for one battery pack in which a plurality of battery cells 2 are stored, the cost can be reduced.

[0030] Furthermore, Fig. 2(b) shows an example of a battery cell 3 provided with a gas pack 41 for retaining the gas discharged from the inside of the battery cell 1 so that the gas is not discharged outside the vehicle. In this way, in the vehicle body, a mechanism for sealing the gas discharged from the secondary battery can be provided.

[0031] Furthermore, if the amount of gas discharged from the secondary battery is very small, the gas may be released to the atmosphere. Here, Fig. 2(c) is a diagram showing the state of the battery cell 3 in which the secondary battery is covered with another outer shell and a semi-permeable membrane 42 is installed in order to prevent moisture intrusion when the gas is released to the atmosphere.

[0032] As shown in FIGS. 2(b) and 2(c), in a secondary battery, a downward force can be generated on the rod by supplying a signal or power through a signal line 44 to a coil 43 arranged around the rod. As shown in FIGS. 2(b) and 2(c), the size of the gas pack 41 can be arbitrarily changed.

[0033] Embodiment 2 FIG. 3(a) is a diagram showing an example of the configuration of another battery cell 4 of a secondary battery. This battery cell 4 includes a case main body portion 51, a gas discharge valve 52, and a wall surface portion 53.

[0034] The case main body portion 51 includes a surface portion 61 and a through hole 62 that penetrates the surface portion 61 in the vertical direction.

[0035] The gas discharge valve 52 includes a rod 71 extending in the vertical direction, a pressure receiving portion 72 connected to the tip of the rod 71, and a compression spring 73 attached to the lower surface of the pressure receiving portion 72. The rod 71 is arranged to penetrate the through hole 62.

[0036] The wall surface portion 53 is formed inside the case main body portion 51. The wall surface portion 53 is formed with a protruding portion 81 that protrudes in the inner 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 formed in the lower surface portion 81a, and a storage portion 81d formed surrounded by the lower surface portion 81a and the side surface portion 81b. The pressure receiving portion 72 of the gas discharge valve 52 and the compression spring 73 are stored in the storage portion 81d.

[0037] 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 above the lower surface portion 81a of the protruding portion 81 in the wall surface portion 53. Thereby, the compression spring 73 can generate a force to press the pressure receiving portion 72 upward.

[0038] On the other hand, the pressure receiving part 72 is pressed upward by the internal pressure of the battery cell 4. As a result, the pressure receiving part 72 can close the through hole 62 of the surface part 61 by the spring force of the compression spring 73 and the internal pressure from inside the battery cell, with an upward force acting thereon.

[0039] Here, the shape of the storage part 81d and the shape of the pressure receiving part 72 are substantially matched. Thereby, even when the pressure receiving part 72 moves up and down or is in the state arranged at the top dead center, the through hole 62 can be closed without generating a deviation in the XY direction.

[0040] Similar to the first embodiment, in the battery cell 4, when a downward external force is applied near the upper part of the rod 71 and this force exceeds the spring force of the compression spring 73 applied to the pressure receiving part 72 and the force of the internal pressure by the battery cell, the pressure receiving part 72 moves downward. Thereby, gas can be discharged from the gap between the through hole 62 and the rod 71.

[0041] As a simpler example, in the secondary battery, a configuration can be adopted in which gas is manually discharged. Fig. 3(b) is an example of a configuration in which gas can be manually discharged.

[0042] More specifically, the upper end part of the rod 31 of the battery cell 1 shown in the first embodiment is made to protrude outside the battery pack in which the battery cell 1 is housed. Thereby, even in the vehicle-mounted state, a part of the valve is arranged at a position accessible to a person, and the gas discharge operation can be carried out at a vehicle dealership or the like.

[0043] In this case as well, by providing a semi-permeable membrane 91 outside the battery pack, near the upper end part of the rod 31 or the like, and separating the inside and outside of the battery pack, it is possible to suppress the intrusion of moisture into the battery cell 1.

[0044] As an application in this case, the gas emission timing can be calculated from the charging and discharging history information of the vehicle, and the user can be notified of the gas emission timing through an information display or the like mounted on the vehicle, thereby promoting the vehicle's arrival at a dealership or the like. Alternatively, as a mechanism for notifying the vehicle manufacturer of the gas emission timing information calculated in this way, the vehicle manufacturer can send a notice to the user to prompt the user to bring the vehicle to the dealership by indicating that the target vehicle is due for gas emission.

[0045] Note that the present invention is not limited to the above-described embodiments, and can be appropriately modified without departing from the spirit thereof. That is, the above description has been appropriately omitted and simplified for the sake of clarity of explanation, and those skilled in the art can easily change, add, or convert each element of the embodiments within the scope of the present invention.

Explanation of Reference Numerals

[0046] 1 Battery cell 2 Battery cell 3 Battery cell 4 Battery cell 11 Case main body 12 Gas discharge valve 21 Surface part 21a Inner surface 22 Protrusion 22a Upper surface part 22b Side surface part 22c Through hole 22d Storage part 22e Opening 31 Rod 32 Pressure receiving part 32a Upper surface 32b Lower surface 33 Tension spring 41 Gas pack 42 Semi-permeable membrane 43 Coil 44 Signal line 51 Case main body 52 Gas discharge valve 53 Wall surface part 61 Surface part 62 Through hole 71 Rod 72 Pressure-receiving part 73 Compression spring 81 Protrusion 81a Bottom surface part 81b Side surface part 81c Through hole 81d Storage part 91 Semi-permeable membrane

Claims

【Claim 1】 A case main body forming the surface of a battery cell, and a gas discharge valve provided in the case main body, comprising: The gas discharge valve has a movable member that can operate in an inner direction and an outer direction, and when a predetermined external force is applied, the movable member moves in the inner direction to open the valve. A secondary battery.

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