Battery gas release valve and battery

Abstract

In a valve body of this gas discharge valve, a substantially-annular main notch for opening the valve body and an auxiliary notch provided in an inner area of the main notch are formed. The main notch and the auxiliary notch are coupled at at least one location. At the location coupling the main notch and the auxiliary notch, the curvature of an inner corner of the bottom part of the main notch is 0.05 or less, and the curvature of an outer corner thereof is 0.05 or more. If t1 is the thickness of the opposite side of the auxiliary notch, when viewed from the coupling location on the valve body, and t2 is the thickness of the lower side of the bottom part of the main notch in the valve body, t2 / t1≥0.16 holds.

Description

[Technical field]

[0001] The present disclosure relates to a gas release valve for a battery and a battery. [Background technology]

[0002] Non-aqueous electrolyte secondary batteries such as alkaline secondary batteries and lithium ion batteries are used as on-board power sources mounted on electric vehicles, hybrid electric vehicles, etc. In non-aqueous electrolyte secondary batteries, a large amount of gas may be generated inside the battery due to improper handling such as dropping into a fire or charging / discharging under abnormal conditions. In this case, it is necessary to quickly release the gas inside the battery to the outside of the battery, so the battery is provided with a gas exhaust valve for quickly releasing the gas inside the battery to the outside of the battery in the event of an abnormality.

[0003] The gas release valve for a battery disclosed in Patent Document 1 has a track-shaped crush groove provided on the outer periphery of the valve body, and an auxiliary crush groove provided in the center of the valve body and perpendicularly connected to the straight portion of the crush groove. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2003-187774 A Summary of the Invention

[0005] In the structure of the gas release valve disclosed in Patent Document 1, when stress is applied to the gas release valve due to vibrations or impacts when ultrasonically connecting the electrode body and the current collector during battery manufacturing, cracks may occur in the crush groove on the outer periphery of the valve body. In that case, the operation of the gas release valve may become unstable when the internal pressure of the battery increases.

[0006] A gas release valve for a battery according to one embodiment of the present disclosure includes: A gas exhaust valve for a battery, which has a thin valve body formed in the battery that opens to release gas within the battery to the outside when the internal pressure of the battery reaches or exceeds a predetermined value, The valve body is formed with a substantially annular main notch for opening the valve body, and an auxiliary notch provided in an inner region of the main notch, the major notch and the minor notch are connected at least at one location; At the junction of the major notch and the minor notch, the curvature R1 of the inside corner of the bottom of the major notch is 0.05 mm -1 and the curvature R2 of the outer corner of the bottom of the main notch is 0.05 mm -1 That's all. If the thickness of the valve body on the opposite side of the auxiliary notch as viewed from the connecting point is t1, and the thickness of the valve body below the bottom of the main notch is t2, then t2 / t1≧0.16.

[0007] In the gas release valve for a battery according to one aspect of the present disclosure, the main notch may have a track shape, and in this case, the auxiliary notch may be connected perpendicularly to a straight portion of the main notch.

[0008] The battery according to one aspect of the present disclosure includes the gas release valve according to one aspect of the present disclosure described above.

[0009] According to one aspect of the present disclosure, it is possible to concentrate stress generated by an increase in the internal pressure of the battery at the inner corner of the bottom of the main notch, and to improve the strength of the outer corner of the bottom of the main notch, which is easily vulnerable to shear stress generated by vibration, impact, etc. Therefore, it is possible to stabilize the operation of the gas release valve when the internal pressure of the battery increases. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a front view showing the inside of a secondary battery provided with a gas release valve according to an embodiment, with the front part of a battery case and the front part of an insulating sheet removed. [Diagram 2] FIG. 2 is a top view of the secondary battery shown in FIG. [Diagram 3]FIG. 3 is a plan view of a gas release valve of the battery according to the embodiment. [Figure 4] FIG. 4 is a cross-sectional view of a connecting portion between a main notch and an auxiliary notch in the gas release valve of the battery according to the first embodiment and the vicinity thereof. [Diagram 5] FIG. 5 is a cross-sectional view of a connecting portion between a main notch and an auxiliary notch in a gas release valve of a battery according to Example 2 and the vicinity thereof. [Figure 6] FIG. 6 is a cross-sectional view of a connecting portion between a main notch and an auxiliary notch in a gas release valve of a battery according to Example 3 and the vicinity thereof. [Figure 7] FIG. 7 is a cross-sectional view of a connecting portion between a main notch and an auxiliary notch in a gas release valve of a battery according to Example 4 and its vicinity. [Figure 8] FIG. 8 is a cross-sectional view of a connecting portion between a main notch and an auxiliary notch in a gas release valve of a battery according to Example 5 and its vicinity. [Figure 9] FIG. 9 is a cross-sectional view of a connecting portion between a main notch and an auxiliary notch in a gas release valve of a battery according to Comparative Example 3 and its vicinity. [Figure 10] FIG. 10 is a cross-sectional view of the connecting portion between the main notch and the auxiliary notch in the gas release valve of the battery in Comparative Example 4 and the vicinity thereof. [Figure 11] FIG. 11 is a plan view of a gas release valve of a battery according to a modified example. [Figure 12] FIG. 12 is a plan view of a gas release valve of a battery according to a modified example. [Figure 13] FIG. 13 is a plan view of a gas release valve of a battery according to a modified example. [Figure 14] FIG. 14 is a plan view of a gas release valve of a battery according to a modified example. [Figure 15] FIG. 15 is a plan view of a gas release valve of a battery according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] (Structure of secondary battery) Hereinafter, a secondary battery provided with a gas release valve according to an embodiment of the present disclosure will be described with reference to the drawings, taking a rectangular secondary battery as an example. Note that the scope of the present invention is not limited to the following embodiment, and can be modified as desired within the scope of the technical concept of the present disclosure.

[0012] FIG. 1 is a front view showing the inside of a prismatic secondary battery 100 with the front portion of the battery case and the front portion of the insulating sheet removed, and FIG. 2 is a top view of the prismatic secondary battery 100. As shown in FIG.

[0013] As shown in FIG. 1 and FIG. 2, the prismatic secondary battery 100 includes a prismatic exterior body 1 having an opening at the top, and a sealing plate 2 that seals the opening. The prismatic exterior body 1 and the sealing plate 2 form a battery case 200. The prismatic exterior body 1 and the sealing plate 2 are each made of metal, and may be made of aluminum or an aluminum alloy, for example. A flat wound electrode body 3 in which a long positive electrode plate and a long negative electrode plate are wound with a long separator sandwiched therebetween is housed in the prismatic exterior body 1 together with a non-aqueous electrolyte. The positive electrode plate is formed by forming a positive electrode active material layer containing a positive electrode active material on a metal positive electrode core, and has a positive electrode core exposed portion in which the positive electrode core is exposed along the longitudinal direction. The negative electrode plate is formed by forming a negative electrode active material layer containing a negative electrode active material on a metal negative electrode core, and has a negative electrode core exposed portion in which the negative electrode core is exposed along the longitudinal direction. The positive electrode core may be made of aluminum or an aluminum alloy, for example. The negative electrode core may be made of, for example, copper or a copper alloy.

[0014] At one end side of the wound electrode body 3 in the direction in which the winding axis extends, a positive electrode core 4a (i.e., a positive electrode core exposed portion) on which a positive electrode active material layer is not formed is arranged in a stacked state. The positive electrode core 4a is wound without a separator or a negative electrode plate interposed therebetween, thereby resulting in a stacked state. A positive electrode current collector 6 is connected to the stacked positive electrode core 4a (hereinafter, sometimes referred to as a positive electrode core stacked portion). The positive electrode current collector 6 may be made of, for example, aluminum or an aluminum alloy.

[0015] At the other end side of the wound electrode body 3 in the direction in which the winding axis extends, a negative electrode core 5a (i.e., a negative electrode core exposed portion) on which a negative electrode active material layer is not formed is arranged in a stacked state. The negative electrode core 5a is wound without a separator or a positive electrode plate interposed therebetween, thereby resulting in a stacked state. A negative electrode current collector 8 is connected to the stacked negative electrode core 5a (hereinafter, sometimes referred to as a negative electrode core stacked portion). The negative electrode current collector 8 may be made of, for example, copper or a copper alloy.

[0016] The positive electrode terminal 7 has a flange portion 7a arranged on the outer side of the sealing plate 2 facing the battery, and an insertion portion inserted into a through hole provided in the sealing plate 2. The positive electrode terminal 7 is made of metal, and may be made of, for example, aluminum or an aluminum alloy. The negative electrode terminal 9 has a flange portion 9a arranged on the outer side of the sealing plate 2 facing the battery, and an insertion portion inserted into a through hole provided in the sealing plate 2. The negative electrode terminal 9 is made of metal, and may be made of, for example, copper or a copper alloy. The negative electrode terminal 9 may have a portion made of aluminum or an aluminum alloy and a portion made of copper or a copper alloy. In this case, the portion made of aluminum or an aluminum alloy may protrude outward from the sealing plate 2, and the portion made of copper or a copper alloy may be connected to the negative electrode current collector 8.

[0017] The positive electrode current collector 6 is fixed to the sealing plate 2 with a resin inner insulating member 10 sandwiched therebetween, and the positive electrode terminal 7 is fixed to the sealing plate 2 with a resin outer insulating member 11 sandwiched therebetween. The negative electrode current collector 8 is fixed to the sealing plate 2 with a resin inner insulating member 12 sandwiched therebetween, and the negative electrode terminal 9 is fixed to the sealing plate 2 with a resin outer insulating member 13 sandwiched therebetween.

[0018] The wound electrode body 3 is housed in the rectangular exterior body 1 while being covered with an insulating sheet 14. The sealing plate 2 is welded to the edge of the opening of the rectangular exterior body 1 by laser welding or the like. The sealing plate 2 is formed with a gas exhaust valve 15 for exhausting gas when the pressure inside the battery reaches or exceeds a predetermined value. The sealing plate 2 has an electrolyte injection hole 16, and after the electrolyte is injected into the rectangular exterior body 1, the electrolyte injection hole 16 is sealed with a sealing plug 17.

[0019] For example, ultrasonic bonding may be used to bond the positive electrode core 4a to the positive electrode current collector 6 and the negative electrode core 5a to the negative electrode current collector 8. The ultrasonic bonding is performed by applying ultrasonic vibration energy to the bonding surfaces while sandwiching the laminated core and current collector plate between a horn and anvil.

[0020] Since stress is applied to the gas release valve 15 due to vibrations, impacts, and the like during this ultrasonic bonding, in this embodiment, as will be described later, the valve body shape of the gas release valve 15 is devised to improve the resistance of the gas release valve 15 to external loads such as vibrations and impacts.

[0021] Fig. 3 is an enlarged view showing the planar configuration of the gas release valve 15. As shown in Fig. 3, the gas release valve 15 is provided so as to cover a track-shaped open hole 2a formed in the sealing plate 2. The gas release valve 15 is made of a thin valve body 21 having a thickness of, for example, about 0.2 mm. The valve body 21 may be integrally formed with the sealing plate 2. The gas release valve 15 has a structure in which, when the internal pressure of the prismatic secondary battery 100 reaches or exceeds a predetermined value, the valve body 21 opens to release gas inside the battery to the outside.

[0022] Specifically, in order to facilitate opening of the valve body 21, a track-shaped main notch 22 is formed on the outer periphery of the valve body 21, and an auxiliary notch 23 is formed in the valve body 21 in an area inside the main notch 22. When the internal pressure of the prismatic secondary battery 100 reaches or exceeds a predetermined value, the main notch 22 and the auxiliary notch 23 are crushed to open the release hole 2a. The depth of the auxiliary notch 23 may be shallower than the depth of the main notch 22. Both ends of the auxiliary notch 23 are vertically connected to the center (connection point 24) of both straight portions of the main notch 22, for example. A pair of areas surrounded by the main notch 22 and the auxiliary notch 23 in the valve body 21 may bulge outward from the battery, for example to form a dome shape, in order to facilitate opening of the valve body 21.

[0023] 3, when the internal pressure of the battery is applied, the inner region of the main notch 22 receives a force tending to deform, and a large stress is applied to the auxiliary notch 23. Here, since both ends of the auxiliary notch 23 are connected to the main notch 22 at the connecting points 24, the stress is concentrated on the connecting points 24. As a result, when the internal pressure of the battery increases, the valve body 21 is reliably fractured from the connecting points 24, and the gas release valve 15 operates quickly.

[0024] The shape of the valve body 21 of the gas release valve 15 will be described in detail below with reference to Examples 1 to 5 and Comparative Examples 1 to 5.

[0025] Example 1 4 is a cross-sectional view of a connecting portion 24 between the main notch 22 and the auxiliary notch 23 and its vicinity in the gas release valve 15 of the embodiment 1. Note that FIG. 4 shows an example of a cross-sectional configuration taken along line AA in FIG.

[0026] In the first embodiment, the curvature R1 of the inner corner 22a of the bottom of the main notch 22 at the connection point 24 is 0.02 mm -1 and the curvature R2 of the bottom outer corner 22b of the main notch 22 is 0.05 mm -1 In addition, if the thickness of the valve body 21 on the opposite side of the auxiliary notch 23 as viewed from the connecting portion 24 is t1, and the thickness of the valve body 21 below the bottom of the main notch 22 is t2, then t1 = 0.18 mm, t2 = 0.03 mm, and t2 / t1 = 0.167.

[0027] Table 1 below shows the above dimensions of Example 1, and the results of simulating the stress applied to the connection point 24 due to vibrations and the like when ultrasonically joining the electrode body and the current collector in battery manufacturing. As shown in Table 1, the stress applied to the connection point 24 in Example 1 is 104.35 MPa, which is smaller than the lower limit of unacceptable stress, 105 MPa.

[0028] In the stress calculation, the anvil contact area of ​​the current collector was vibrated under specified vibration conditions (frequency 20 kHz, amplitude 0.015 mm). These vibration conditions were set by assuming an equivalent anvil vibration based on the actual vibration measurements of the horn and anvil during the bonding process. The lower limit of the allowable stress (105 MPa) was derived from a case in which damage occurred to the gas exhaust valve 15 through actual measurements.

[0029] [Table 1]

[0030] Example 2 5 is a cross-sectional view of a connecting portion 24 between the main notch 22 and the auxiliary notch 23 and its vicinity in the gas release valve 15 of the embodiment 2. Note that FIG. 5 shows an example of the cross-sectional configuration along the line AA in FIG.

[0031] In the second embodiment, the curvature R1 of the inner corner 22a of the bottom of the main notch 22 at the connection point 24 is 0.03 mm -1 and the curvature R2 of the bottom outer corner 22b of the main notch 22 is 0.05 mm -1 In addition, if the thickness of the valve body 21 on the opposite side of the auxiliary notch 23 as viewed from the connecting portion 24 is t1, and the thickness of the valve body 21 below the bottom of the main notch 22 is t2, then t1 = 0.18 mm, t2 = 0.03 mm, and t2 / t1 = 0.167.

[0032] Table 1 shows the dimensions of Example 2 and the results of simulating the stress applied to the connection point 24 due to vibrations and the like when ultrasonically bonding the electrode body and the current collector in battery manufacturing. As shown in Table 1, the stress applied to the connection point 24 in Example 2 is 104.35 MPa, which is smaller than the lower limit of unacceptable stress, 105 MPa. The stress was calculated in the same manner as in Example 1.

[0033] Example 3 6 is a cross-sectional view of a connecting portion 24 between the main notch 22 and the auxiliary notch 23 and its vicinity in the gas release valve 15 of the embodiment 3. Note that FIG. 6 shows an example of the cross-sectional configuration along the line AA in FIG.

[0034] In the third embodiment, the curvature R1 of the inner corner 22a of the bottom of the main notch 22 at the connection point 24 is 0.04 mm -1 and the curvature R2 of the bottom outer corner 22b of the main notch 22 is 0.05 mm -1 In addition, if the thickness of the valve body 21 on the opposite side of the auxiliary notch 23 as viewed from the connecting portion 24 is t1, and the thickness of the valve body 21 below the bottom of the main notch 22 is t2, then t1 = 0.18 mm, t2 = 0.03 mm, and t2 / t1 = 0.167.

[0035] Table 1 shows the dimensions of Example 3 and the results of simulating the stress applied to the connection point 24 due to vibrations and the like when ultrasonically bonding the electrode body and the current collector in battery manufacturing. As shown in Table 1, the stress applied to the connection point 24 in Example 3 is 100.36 MPa, which is smaller than the lower limit of unacceptable stress, 105 MPa. The stress was calculated in the same manner as in Example 1.

[0036] Example 4 7 is a cross-sectional view of a connecting portion 24 between the main notch 22 and the auxiliary notch 23 and its vicinity in the gas release valve 15 of the embodiment 4. Note that FIG. 7 shows an example of the cross-sectional configuration along the line AA in FIG.

[0037] In the fourth embodiment, the curvature R1 of the inner corner 22a of the bottom of the main notch 22 at the connection point 24 is 0.02 mm -1 and the curvature R2 of the outer corner 22b of the bottom of the main notch 22 is 0.1 mm -1 In addition, if the thickness of the valve body 21 on the opposite side of the auxiliary notch 23 as viewed from the connecting portion 24 is t1, and the thickness of the valve body 21 below the bottom of the main notch 22 is t2, then t1 = 0.18 mm, t2 = 0.03 mm, and t2 / t1 = 0.167.

[0038] Table 1 shows the above dimensions of Example 4, and the results of simulating the stress applied to the connection point 24 due to vibrations and the like when ultrasonically bonding the electrode body and the current collector in the manufacture of the battery. As shown in Table 1, the stress applied to the connection point 24 in Example 4 is 102.55 MPa, which is smaller than the lower limit of unacceptable stress, 105 MPa. The stress was calculated in the same manner as in Example 1.

[0039] Example 5 8 is a cross-sectional view of a connecting portion 24 between the main notch 22 and the auxiliary notch 23 and its vicinity in the gas release valve 15 of the embodiment 5. Note that FIG. 8 shows an example of the cross-sectional configuration along the line AA in FIG.

[0040] In the fifth embodiment, the curvature R1 of the inner corner 22a of the bottom of the main notch 22 at the connection point 24 is 0.03 mm -1 and the curvature R2 of the outer corner 22b of the bottom of the main notch 22 is 0.1 mm -1 In addition, if the thickness of the valve body 21 on the opposite side of the auxiliary notch 23 as viewed from the connecting portion 24 is t1, and the thickness of the valve body 21 below the bottom of the main notch 22 is t2, then t1 = 0.18 mm, t2 = 0.03 mm, and t2 / t1 = 0.167.

[0041] Table 1 shows the above dimensions of Example 5, and the results of simulating the stress applied to the connection point 24 due to vibrations and the like when ultrasonically bonding the electrode body and the current collector in the manufacture of the battery. As shown in Table 1, the stress applied to the connection point 24 in Example 5 is 102.00 MPa, which is smaller than the lower limit of the unacceptable stress of 105 MPa. The stress was calculated in the same manner as in Example 1.

[0042] In Comparative Example 1, the curvature R1 of the inner corner 22a of the bottom of the main notch 22 at the connection point 24 is 0.02 mm -1 and the curvature R2 of the bottom outer corner 22b of the main notch 22 is 0.02 mm -1In addition, if the thickness of the valve body 21 on the opposite side of the auxiliary notch 23 as viewed from the connecting portion 24 is t1, and the thickness of the valve body 21 below the bottom of the main notch 22 is t2, then t1 = 0.38 mm, t2 = 0.03 mm, and t2 / t1 = 0.079.

[0043] Table 1 shows the dimensions of Comparative Example 1 and the results of simulating the stress applied to the connection point 24 due to vibrations and the like when ultrasonically bonding the electrode body and the current collector in battery manufacturing. As shown in Table 1, the stress applied to the connection point 24 in Comparative Example 1 is 120.79 MPa, which is greater than the lower limit of unacceptable stress, 105 MPa. The stress was calculated in the same manner as in Example 1.

[0044] In Comparative Example 2, the curvature R1 of the inner corner 22a of the bottom of the main notch 22 at the connection point 24 is 0.02 mm -1 and the curvature R2 of the bottom outer corner 22b of the main notch 22 is 0.02 mm -1 In addition, if the thickness of the valve body 21 on the opposite side of the auxiliary notch 23 as viewed from the connecting portion 24 is t1, and the thickness of the valve body 21 below the bottom of the main notch 22 is t2, then t1 = 0.28 mm, t2 = 0.03 mm, and t2 / t1 = 0.107.

[0045] Table 1 shows the dimensions of Comparative Example 2 and the results of simulating the stress applied to the connection point 24 due to vibrations and the like when ultrasonically bonding the electrode body and the current collector in the battery manufacturing process. As shown in Table 1, the stress applied to the connection point 24 in Comparative Example 2 is 118.74 MPa, which is greater than the lower limit of unacceptable stress, 105 MPa. The stress was calculated in the same manner as in Example 1.

[0046] In Comparative Example 3, the curvature R1 of the inner corner 22a of the bottom of the main notch 22 at the connection point 24 is 0.02 mm -1 and the curvature R2 of the bottom outer corner 22b of the main notch 22 is 0.02 mm -1In addition, if the thickness of the valve body 21 on the opposite side of the auxiliary notch 23 as viewed from the connecting portion 24 is t1, and the thickness of the valve body 21 below the bottom of the main notch 22 is t2, then t1 = 0.18 mm, t2 = 0.03 mm, and t2 / t1 = 0.167.

[0047] 9 is a cross-sectional view of a connecting portion 24 between the main notch 22 and the auxiliary notch 23 and its vicinity in the gas release valve 15 of Comparative Example 3. Note that Fig. 9 shows an example of the cross-sectional configuration along line AA in Fig. 3 .

[0048] Table 1 shows the dimensions of Comparative Example 3 and the results of simulating the stress applied to the connection point 24 due to vibrations and the like when ultrasonically bonding the electrode body and the current collector in the battery manufacturing process. As shown in Table 1, the stress applied to the connection point 24 in Comparative Example 3 is 109.03 MPa, which is greater than the lower limit of unacceptable stress, 105 MPa. The stress was calculated in the same manner as in Example 1.

[0049] In Comparative Example 4, the curvature R1 of the inner corner 22a of the bottom of the main notch 22 at the connection point 24 is 0.04 mm -1 and the curvature R2 of the bottom outer corner 22b of the main notch 22 is 0.02 mm -1 In addition, if the thickness of the valve body 21 on the opposite side of the auxiliary notch 23 as viewed from the connecting portion 24 is t1, and the thickness of the valve body 21 below the bottom of the main notch 22 is t2, then t1 = 0.18 mm, t2 = 0.03 mm, and t2 / t1 = 0.167.

[0050] 10 is a cross-sectional view of a connecting portion 24 between the main notch 22 and the auxiliary notch 23 and its vicinity in the gas release valve 15 of Comparative Example 4. Note that Fig. 10 shows an example of the cross-sectional configuration along line AA in Fig. 3 .

[0051] Table 1 shows the dimensions of Comparative Example 4 and the results of simulating the stress applied to the connection point 24 due to vibrations and the like when ultrasonically bonding the electrode body and the current collector in the battery manufacturing process. As shown in Table 1, the stress applied to the connection point 24 in Comparative Example 4 is 109.03 MPa, which is greater than the lower limit of unacceptable stress, 105 MPa. The stress was calculated in the same manner as in Example 1.

[0052] In Comparative Example 5, the curvature R1 of the inner corner 22a of the bottom of the main notch 22 at the connection point 24 is 0.03 mm -1 and the curvature R2 of the outer corner 22b of the bottom of the main notch 22 is 0.1 mm -1 In addition, if the thickness of the valve body 21 on the opposite side of the auxiliary notch 23 as viewed from the connecting portion 24 is t1, and the thickness of the valve body 21 below the bottom of the main notch 22 is t2, then t1 = 0.3 mm, t2 = 0.03 mm, and t2 / t1 = 0.100.

[0053] Table 1 shows the dimensions of Comparative Example 5 and the results of simulating the stress applied to the connection point 24 due to vibrations and the like when ultrasonically bonding the electrode body and the current collector in the battery manufacturing process. As shown in Table 1, the stress applied to the connection point 24 in Comparative Example 5 is 111.13 MPa, which is greater than the lower limit of unacceptable stress, 105 MPa. The stress was calculated in the same manner as in Example 1.

[0054] (Effects of the embodiment) From the above-described Examples 1 to 5 and Comparative Examples 1 to 5, in the gas exhaust valve 15 of this embodiment, the curvature R1 of the inner corner 22a of the bottom of the main notch 22 at the connecting portion 24 between the main notch 22 and the auxiliary notch 23 is set to 0.05 mm -1 or less, and the curvature R2 of the outer corner 22b of the bottom of the main notch 22 is 0.05 mm -1It can be seen that by satisfying the above, and further by making the wall thickness t1 on the opposite side of the auxiliary notch 23 in the valve body 21 as viewed from the connecting point 24, and the wall thickness t2 below the bottom of the main notch 22 in the valve body 21 such that t2 / t1 ≧ 0.16, the resistance of the valve body 21 to external loads such as vibration and impact is improved.

[0055] The outer corner 22b of the bottom of the main notch 22 is easily vulnerable to stress in the shear direction (in this embodiment, the normal direction of the sealing plate 2) generated by vibration, impact, etc. Therefore, the curvature R1 of the inner corner 22a of the bottom of the main notch 22 is set to 0.05 mm -1 or less, and the curvature R2 of the outer corner 22b of the bottom of the main notch 22 is 0.05 mm -1 By satisfying the above, stress generated by an increase in the battery's internal pressure is easily concentrated at the inner corner 22a of the bottom of the main notch 22. In addition, by setting the wall thickness t1 on the opposite side of the auxiliary notch 23 as viewed from the connecting portion 24 of the valve body 21 and the wall thickness t2 on the lower side of the bottom of the main notch 22 of the valve body 21 to t2 / t1≧0.16, in other words, by making the wall thickness t1 on the opposite side of the auxiliary notch 23 as viewed from the connecting portion 24 of the valve body 21 thinner, it is possible to improve the resistance to shear stress at the outer corner 22b of the bottom of the main notch 22. Therefore, it is possible to stabilize the operation of the gas release valve 15 when the battery's internal pressure increases.

[0056] Furthermore, in the gas release valve 15 of this embodiment, if the main notches 22 have a track shape, the gas release valve 15 opens in a more preferable shape, allowing the gas to be released more smoothly. In this case, if the auxiliary notches 23 are connected perpendicularly to the straight portions of the main notches 22, the gas release valve 15 opens in a more preferable shape, allowing the gas to be released even more smoothly.

[0057] (Other embodiments) Although the embodiments of the present disclosure (including examples; the same applies below) have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the disclosure. In other words, the description of the above-described embodiments is essentially merely illustrative, and is not intended to limit the present invention, its applications, or its uses.

[0058] For example, in the above embodiment, a prismatic secondary battery having a flat wound electrode body is exemplified as the battery, but the type of battery is not particularly limited, and the present disclosure can be applied to various batteries having different electrode body constituent materials and electrolytes, in addition to lithium secondary batteries. Furthermore, the present disclosure is not limited to prismatic batteries, and can be applied to batteries of various shapes (cylindrical, etc.).

[0059] In the above embodiment, both ends of the auxiliary notch 23 are connected to the main notch 22. However, instead of this, for example, as shown in FIG. 11, only one end of the auxiliary notch 23 may be connected to the main notch 22.

[0060] Further, in the above-described embodiment, only one auxiliary notch 23 is provided, but instead, for example, as shown in FIG. 12, two auxiliary notches 23 may be provided, or three or more auxiliary notches 23 may be provided.

[0061] In the above-described embodiment, the auxiliary notches 23 are provided so as to pass through the center of the valve body 21, but instead, as shown in Fig. 13, for example, the auxiliary notches 23 may be provided so as not to pass through the center of the valve body 21. In the above-described embodiment, the auxiliary notches 23 are connected perpendicularly to the main notches 22, but, as shown in Fig. 13, for example, the auxiliary notches 23 may be connected obliquely to the main notches 22.

[0062] In the above embodiment, the planar shape of the valve body 21 is a track shape, but it is not limited to this and may be a polygonal shape such as a perfect circle, an ellipse, or a square. Similarly, the planar shape of the main notch 22 formed on the outer periphery of the valve body 21 is not limited to a track shape and may be an annular shape such as a perfect circle, an ellipse, or a square. The main notch 22 does not necessarily have to be formed in a closed ring shape and may be a substantially annular shape with a partially interrupted portion. The planar shape of the valve body 21 and the main notch 22 may be different. FIG. 14 shows an example in which the planar shapes of the valve body 21 and the main notch 22 are square.

[0063] Furthermore, in the above-described embodiment, the auxiliary notches 23 are connected to the straight portions of the main notches 22, but instead, for example, as shown in Fig. 15, the auxiliary notches 23 may be connected to curved portions of the main notches 22. Furthermore, in the above-described embodiment, the auxiliary notches 23 are provided in the minor axis direction of the main notches 22, but instead, for example, as shown in Fig. 15, the auxiliary notches 23 may be provided in the major axis direction of the main notches 22. [Explanation of symbols]

[0064] 100 Prismatic secondary battery 200 Battery Case 1. Rectangular exterior body 2 Sealing plate 2a open hole 3 Wound electrode body 4 Positive plate 4a Positive electrode core 5 Negative plate 5a Negative electrode core 6 Positive electrode current collector 7 Positive terminal 7a Tsubabe 8 Negative electrode current collector 9 Negative terminal 9a Tsubabe 10 Inner insulating member 11 External insulating member 12 Inner insulating member 13 External insulating member 14 Insulation sheet 15 Gas exhaust valve 16 Electrolyte injection hole 17 Sealing plug 21 Valve body 22 Major notch 22a Bottom inside corner of main notch 22b Outside corner of bottom of main notch 23 Auxiliary notch 24 Connection points

Claims

1. A gas exhaust valve for a battery, which has a thin valve body formed in the battery that opens to release gas within the battery to the outside when the internal pressure of the battery reaches or exceeds a predetermined value, The valve body is formed with a substantially annular main notch for opening the valve body, and an auxiliary notch provided in an inner region of the main notch, the major notch and the minor notch are connected at least at one location; At a junction of the main notch and the auxiliary notch, a radius of curvature R1 of an inner corner of a bottom of the main notch is 0.05 mm −1 or less, and a radius of curvature R2 of an outer corner of a bottom of the main notch is 0.05 mm −1 or more; a wall thickness on an opposite side of the auxiliary notch as viewed from the connecting portion of the valve body is t1, and a wall thickness on a lower side of the bottom of the main notch of the valve body is t2, where t2 / t1 is greater than or equal to 0.16; Battery gas release valve.

2. The shape of the main notch is a track shape. A gas release valve for a battery according to claim 1.

3. The auxiliary notch is connected perpendicularly to the straight portion of the main notch. A gas release valve for a battery according to claim 2.

4. The battery according to any one of claims 1 to 3, further comprising a gas exhaust valve. battery.

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