Battery pack

Abstract

The battery pack according to an aspect of the present disclosure is provided with a secondary battery and a battery case containing the secondary battery. The battery case has an exhaust part that discharges gas emitted from the secondary battery out of the battery case. The exhaust part has at least one or more slits that open in response to a deformation in the exhaust part that occurs in association with an increase in pressure inside the battery case. Furthermore, it is preferable that the slits in the exhaust part operate reversibly in accordance with the pressure inside the battery case.

Description

[Technical Field]

[0001] The present disclosure relates to a battery pack, and more particularly to a battery pack having an exhaust section. [Background technology]

[0002] Battery packs are required to be airtight to protect the secondary batteries housed inside from dust and water. Furthermore, because secondary batteries may generate gas in the event of an abnormality, battery packs are also required to have a gas exhaust function to prevent explosion. Patent Document 1 discloses a battery pack that ensures airtightness by using a battery case with a sealing member sandwiched between an upper lid and a lower lid, and that, in the event of an abnormality, melts the sealing member due to the heat of gas generated from the secondary battery, thereby forming an exhaust path. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2016 / 076417 Summary of the Invention [Problem to be solved by the invention]

[0004] In the battery pack disclosed in Patent Document 1, it takes time for the exhaust path to be formed, so if gas is rapidly released from the secondary battery, the exhaust may not be completed in time.

[0005] Therefore, an object of the present disclosure is to provide a battery pack that can vent in response to an increase in internal pressure. [Means for solving the problem]

[0006] A battery pack according to one aspect of the present disclosure comprises a secondary battery and a battery case that houses the secondary battery, the battery case having an exhaust section that exhausts gas emitted from the secondary battery to the outside of the battery case, and the exhaust section having at least one or more slits that open in response to deformation of the exhaust section that occurs in response to an increase in pressure inside the battery case. [Effects of the Invention]

[0007] According to a battery pack according to one aspect of the present disclosure, the interior of the battery case is normally sealed to protect it from dust and water, while explosion of the battery case can be prevented in the event of an abnormality. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view of a battery pack according to an embodiment; [Figure 2] FIG. 2 is a plan cross-sectional view seen in the direction AA of FIG. [Figure 3] FIG. 2 is a front cross-sectional view seen in the direction BB in FIG. [Figure 4] FIG. 2 is an enlarged view of a part of an exhaust unit according to an example embodiment. [Figure 5] 4(a) and 4(b) are cross-sectional views taken along the CC direction in Fig. 4, where 4(a) shows a normal state in which the pressure inside the battery case is low, 4(b) shows an abnormal state in which the pressure inside the battery case is high, and 4(c) is a cross-sectional view taken along the DD direction in Fig. 4 in an abnormal state in which the pressure inside the battery case is high. [Figure 6] 5(a) to 5(e) are views corresponding to FIG. 4 in another example of the embodiment. [Figure 7] FIG. 5 is a view corresponding to FIG. 4 in another example of the embodiment, showing how the exhaust part deforms in response to an increase in pressure inside the battery case. DETAILED DESCRIPTION OF THE INVENTION

[0009] Embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. It should be noted that, when multiple embodiments or variations are included below, it is anticipated from the outset that new embodiments will be constructed by appropriately combining their characteristic features. Furthermore, the multiple drawings include schematic diagrams, and the dimensional ratios of the depth, width, height, etc. of each component between different drawings do not necessarily match. Furthermore, among the components described below, components that are not recited in the independent claim representing the highest concept are optional components and are not essential components. Furthermore, when the term "approximately" is used in this specification, it is used in the same sense as the term "approximately," and the requirement of "approximately" is met if the components are substantially the same.

[0010] In the following embodiments, the battery pack 10 is described as having a generally rectangular parallelepiped shape, but in the drawings and the description of the embodiments, the X direction indicates the depth direction of the battery pack 10 (battery case 12), the Y direction indicates the width direction of the battery pack 10 (battery case 12), and the Z direction indicates the height direction of the battery pack 10 (battery case 12). The X direction, Y direction, and Z direction are perpendicular to each other.

[0011] First, an outline of the battery pack 10 will be described with reference to Figures 1 to 3. Figure 1 is a perspective view of a battery pack according to an embodiment. Figure 2 is a plan cross-sectional view taken along the AA direction in Figure 1 (a cross-sectional view taken along the XZ plane passing through the center of the battery pack 10 in the width direction). Figure 3 is a front cross-sectional view taken along the BB direction in Figure 1 (a cross-sectional view taken along the YZ plane passing through the secondary battery 16 in the depth direction of the battery pack 10). The battery pack 10 can be used as a power source for various electrical devices, and may be, for example, a small-capacity battery pack for small portable devices such as a personal computer (PC) or an electric cleaner.

[0012] The battery pack 10 includes a battery case 12. The shape of the battery case 12 is not particularly limited, but the battery case 12 may be, for example, a substantially rectangular parallelepiped shape as shown in FIG. 1. The battery case 12 is made of, for example, a metal material or a resin material. The battery case 12 has the function of protecting the secondary battery 16 housed therein from dust and water.

[0013] The battery case 12 has an exhaust section 14 that exhausts gas emitted from the secondary batteries 16 to the outside of the battery case 12. The location, number, size, etc. of the exhaust section 14 are not particularly limited, and one exhaust section 14 may be provided on a portion of one side surface in the depth direction of the battery case 12, as shown in FIG. 1 . The size of the exhaust section 14 may be sufficient to exhaust gas emitted from the secondary batteries 16 and prevent the battery case 12 from exploding. As will be described in detail later, the exhaust section 14 has the function of sealing the inside of the battery case 12 under normal circumstances, but deforming and opening in response to an increase in pressure inside the battery case 12 under abnormal circumstances. This prevents dust and water from entering the battery case 12 while preventing the battery case 12 from exploding.

[0014] The battery pack 10 may include a covering member 15 that covers the exhaust section 14. This more reliably protects the secondary battery 16 housed in the battery case 12 from dust and water. The covering member 15 is fixed to the battery case 12 by a fixing means such as an adhesive so as to close the exhaust section 14. The covering member 15 may be made of a breathable and waterproof material such as Gore-Tex (registered trademark) that allows exhaust gas from the inside of the battery case 12 to pass through but blocks liquids such as water from the outside.

[0015] The battery pack 10 includes a secondary battery 16 housed in a battery case 12. The number, shape, size, etc. of the secondary batteries 16 are not particularly limited, and the battery pack 10 may house multiple cylindrical secondary batteries 16 in the battery case 12, as shown in FIG. 2, for example. A non-aqueous electrolyte secondary battery such as a lithium-ion battery is used as the secondary battery 16. The secondary battery 16 may have a positive electrode terminal 16a and a negative electrode terminal 16b at both ends in the depth direction. The secondary battery 16 may have, for example, an electrode group including a positive electrode and a negative electrode, an outer can that houses the electrode group together with an electrolyte, and a sealing plate that seals the opening of the outer can via an insulating gasket. The outer can may be electrically connected to the negative electrode of the electrode group, and the conductive sealing plate may be connected to the positive electrode. It should be noted that current collecting members such as metal plates are connected to the positive electrode terminal 16a and the negative electrode terminal 16b of the secondary battery 16, and the battery case 12 is provided with connection terminals for connecting the positive electrode and the negative electrode to the outside, but in FIG. 2 , electrical connection members such as the current collecting members and connection terminals are omitted.

[0016] As shown in FIG. 3 , the battery case 12 may have a housing portion 22 that houses a secondary battery 16 in the internal space of an inner wall 20 formed around the periphery. Exhaust passages 18 are formed between the housing portions 22 and between the housing portion 22 and the inner wall 20, through which high-temperature gas discharged from the secondary battery 16 flows in the event of an abnormality. The exhaust passages 18 are a passage for the gas discharged from the secondary battery 16, and the gas may be cooled by mixing with the air in the exhaust passages 18 as it flows through the exhaust passages 18. For example, in FIG. 2 , if the sealing plate on the positive terminal 16a side of the secondary battery 16 is designed to be destroyed before the outer can, the high-temperature gas discharged from the secondary battery 16 travels a long distance through the exhaust passages 18 before reaching the exhaust portion 14, thereby efficiently lowering the gas temperature. The battery case 12 may be designed so that the outer can is destroyed, and preferably, the outer can is destroyed after the sealing plate is destroyed.

[0017] 3, the battery case 12 may be divided into two half cases 12a and 12b in the height direction. By stacking the half cases 12a and 12b facing each other, it is possible to cover the entire secondary battery 16. The half cases 12a and 12b are in contact only at the tips of their inner walls 20, and the tips of the other parts other than the inner walls 20 face each other with a gap between them, forming a space within the battery case 12, which serves as the exhaust passage 18.

[0018] Next, the exhaust section 14 will be described in detail with reference to FIGS.

[0019] FIG. 4 is an enlarged view of a portion of the exhaust section 14 in one example of the embodiment. The exhaust section 14 has at least one slit 30, and preferably has a plurality of slits 30 as shown in FIG. 4. The slit 30 is a thin line that penetrates the exhaust section 14 in the thickness direction. Note that the slit 30 does not have to penetrate over its entire length, and a portion of the slit 30 may be non-penetrating. The width of the slit 30 is, for example, 5 μm to 2 mm, and preferably 30 μm to 1 mm. The thickness of the exhaust section 14 is not particularly limited as long as it is large enough to allow the slit 30 to open in the event of an abnormality, as will be described later.

[0020] As shown in FIG. 4, the slits 30 may each have the same shape with pointed bent portions 30a, 30b, and may be aligned so that the bent portions 30a, 30b are aligned vertically and alternately oriented in opposite directions horizontally. The sharp bent portions 30a, 30b of the slits 30 can rupture the covering member 15 when the slit 30 opens, as described below, making it easier to exhaust gas from the exhaust portion 14. Alternatively, multiple slits 30 may overlap horizontally, as shown in FIG. 4. The greater the overlap width w, the more the opening can expand in response to pressure inside the battery case 12 in the event of an abnormality.

[0021] Because the exhaust section 14 has the slit 30, the slit 30 portion deforms preferentially in accordance with the deformation of the exhaust section 14 that occurs in response to an increase in pressure inside the battery case 12. Therefore, when gas is discharged from the secondary battery 16, the pressure inside the battery case 12 increases, and the exhaust section 14 is pressed from inside the battery case 12, opening the slit 30 portion, allowing the gas to be discharged from the exhaust section 14 to the outside.

[0022] FIG. 5 is a cross-sectional view taken along the CC direction in FIG. 4. FIG. 5(a) shows a normal state in which the pressure inside the battery case 12 is low, and FIG. 5(b) shows an abnormal state in which the pressure inside the battery case 12 is high. FIG. 5(c) is a cross-sectional view taken along the DD direction in FIG. 4 in an abnormal state in which the pressure inside the battery case 12 is high. As shown in FIG. 5(a), the exhaust section 14 is generally flat under normal conditions, and the width of the slits 30 at the bent portions 30a and 30b is narrow enough to prevent dust and water from entering the battery case 12. However, as shown in FIG. 5(b), under abnormal conditions, the exhaust section 14 receives pressure from inside the battery case 12, pushing the slits 30 outward. The width of the slits 30 at the bent portions 30a and 30b widens, allowing gas g released from the secondary battery 16 to be exhausted. This prevents the battery case 12 from exploding. Furthermore, since the bending direction of the bending portions of the multiple slits 30 is opposite for each adjacent row, the direction in which gas g is discharged can be made different for each adjacent row of slits 30, as shown in Figures 5(b) and 5(c), thereby reducing the concentration of gas g outside near the exhaust section 14 and reducing the risk of gas g burning.

[0023] In the exhaust section 14, the slit 30 preferably operates reversibly due to the pressure inside the battery case 12. That is, when the gas is exhausted and the pressure inside the battery case 12 drops, the slit 30 preferably returns to its normal position. This allows the airtight state to be maintained again after exhaust, thereby preventing the secondary battery 16 from burning due to the inflow of air from the outside.

[0024] The exhaust section 14 is preferably made of aluminum or stainless steel, which makes the exhaust section 14 less susceptible to corrosion by gases discharged from the secondary battery 16 and allows for stable operation. Furthermore, aluminum and stainless steel are easily elastically deformed, allowing the exhaust section 14 to reversibly operate over a relatively wide deformation range.

[0025] Next, another example of the exhaust unit 14 will be described with reference to Fig. 6. Figs. 6(a) to 6(e) are views corresponding to Fig. 4 in another example of the embodiment.

[0026] 6(a), the slits 300 are all the same shape with sharp bends, and are aligned so that the bends are aligned vertically and alternately oriented in opposite directions horizontally. The slits 300 do not overlap horizontally.

[0027] In Figure 6(b), the slits 302 each have the same shape with rounded bends 30a, 30b, and are aligned so that the bends are aligned vertically and alternately aligned horizontally. Furthermore, the slits 302 do not overlap horizontally. As shown in Figures 6(a) and 6(b), when the slits do not overlap horizontally, the exhaust section 14 is relatively resistant to deformation, making it easier for the exhaust section 14 to operate reversibly in response to the pressure inside the battery case 12.

[0028] 6(c), linear slits 304 of the same length facing two mutually perpendicular directions are periodically aligned, and the collection of slits 304 forms a lattice pattern. In this case, the exhaust direction of gas g in the event of an abnormality as shown in FIG. 5(b) is likely to be aligned in the same direction, but if the concentration of gas g outside the vicinity of exhaust unit 14 is sufficiently low and there is little risk of gas g burning, exhaust unit 14 may have such a collection of slits 304.

[0029] 6(d), the slits 306 are each linear and of the same length extending horizontally, aligned with both ends aligned vertically, and aligned so that the heights of the slits in every other row are the same horizontally. Furthermore, the slits 306 overlap horizontally.

[0030] In Figure 6(e), the slits 308 are each linear and of the same length extending horizontally, aligned vertically with both ends aligned, and aligned so that the vertical heights of every other row are the same in the horizontal direction. Furthermore, the multiple slits 308 do not overlap horizontally. When the slits 306 and 308 are linear, as shown in Figures 6(d) and 6(e), the slits can be made relatively easily.

[0031] 4 and 6(a) to (e) are merely examples, and the exhaust section 14 may have a plurality of types of slits with different shapes.

[0032] Next, another example of the exhaust section 14 will be described with reference to FIG. 7. FIG. 7 is a diagram corresponding to FIG. 4 for another example of the embodiment, and illustrates how the exhaust section 14 deforms in response to an increase in pressure inside the battery case 12. In FIG. 7, the upper diagram shows the exhaust section 14 in a normal state. The exhaust section 14 has multiple slits 310 formed in both the vertical and horizontal directions, and the pattern formed by the slits 310 is 90° rotationally symmetric, vertically symmetric, and horizontally symmetric. When the pressure inside the battery case 12 increases, the exhaust section 14 deforms as shown in the middle and lower diagrams, forming an opening, allowing gas released from the secondary battery 16 to be exhausted. The exhaust section 14 having the slits 310 configured as illustrated in FIG. 7 can operate reversibly while widening the opening. [Explanation of symbols]

[0033] 10 battery pack, 12 battery case, 12a, 12b half case, 14 exhaust section, 15 covering member, 16 secondary battery, 18 exhaust passage, 20 inner wall, 22 storage section, 30, 300, 302, 304, 306, 308, 310 slit, 30a, 30b, 30c, 30d bent section

Claims

1. A secondary battery; a battery case that houses the secondary battery, the battery case has an exhaust part that exhausts gas discharged from the secondary battery to the outside of the battery case, the exhaust portion has at least one slit that opens in response to deformation of the exhaust portion that occurs in response to an increase in pressure inside the battery case, The slit has a predetermined width, The exhaust portion is a battery pack, wherein the slit having a predetermined width reversibly operates in response to pressure inside the battery case.

2. The battery pack according to claim 1 , wherein the exhaust portion has a plurality of slits.

3. 3. The battery pack according to claim 1, wherein the exhaust portion is made of aluminum or stainless steel.

4. 4. The battery pack according to claim 1, wherein the slit has a linear shape.

5. 4. The battery pack according to claim 1, wherein the slit has a bent portion.

6. 6. The battery pack according to claim 1, wherein a plurality of the slits overlap each other.

7. The battery pack according to any one of claims 1 to 6, further comprising a covering member that covers the exhaust portion.

8. The battery pack according to claim 7 , wherein the covering member is made of a breathable and waterproof material.

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