Battery pack

Abstract

A battery pack of one embodiment of the present disclosure includes a secondary battery and a battery case that accommodates the secondary battery. The battery case has a gas exhaust portion that exhausts gas discharged from the secondary battery to the outside of the battery case. The gas exhaust portion has at least one or more slits that open in accordance with deformation of the gas exhaust portion due to an increase in pressure in the battery case. Further, preferably, the slits reversibly operate in accordance with the pressure in the battery case for the gas exhaust portion.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a battery pack, and particularly to a battery pack having an exhaust portion. BACKGROUND

[0002] For a battery pack, in order to protect a secondary battery housed inside from dust, water, etc., airtightness is required. In addition, since the secondary battery sometimes generates gas in an abnormal situation, for a battery pack, in order to prevent breakage, a gas exhaust function is also required. In Patent Literature 1, a battery pack is disclosed which is configured to ensure airtightness by using a battery case in which a sealing member is sandwiched by an upper cover and a lower cover, and in an abnormal situation, the sealing member is melted by heat of gas generated from the secondary battery to form an exhaust path.

[0003] Prior art documents

[0004] Patent documents

[0005] Patent Literature 1: International Publication No. 2016 / 076417 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] The battery pack disclosed in Patent Literature 1 takes time to form an exhaust path, and thus in a case where gas is rapidly released from the secondary battery, there is a possibility that the exhaust is not performed in time.

[0008] Therefore, an object of the present disclosure is to provide a battery pack capable of performing exhaust in accordance with an increase in internal pressure.

[0009] SOLUTION TO PROBLEM

[0010] A battery pack according to one aspect of the present disclosure is characterized by including a secondary battery and a battery case housing the secondary battery, the battery case having an exhaust portion that exhausts gas discharged from the secondary battery to the outside of the battery case, the exhaust portion having at least one or more slits that open in accordance with deformation of the exhaust portion due to an increase in pressure inside the battery case.

[0011] EFFECT OF THE INVENTION

[0012] The battery pack according to one aspect of the present disclosure can airtight the inside of the battery case in a normal situation to protect the inside of the battery case from dust, water, etc., and can suppress breakage of the battery case in an abnormal situation. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is a perspective view of a battery pack as one example of an embodiment.

[0014] Figure 2 is a plan view observed in the A-A direction of Figure 1

[0015] Figure 3 is a front view observed in the B-B direction of Figure 1

[0016] Figure 4 is a view in which a part of the exhaust portion of one example of the embodiment is enlarged.

[0017] Figure 5 (a) and (b) of Figure 5 are cross-sectional views observed in the C-C direction of Figure 4 (a) of Figure 5 represents a state in a normal case in which the pressure in the battery case is low, Figure 5 (b) represents a state in an abnormal case in which the pressure in the battery case is high. Figure 5 (c) is a cross-sectional view observed in the D-D direction of Figure 4 in a state in which the pressure in the battery case is high.

[0018] Figure 6 (a) to (e) of Figure 6 are views corresponding to Figure 4 of another example of the embodiment, respectively.

[0019] Figure 7 is a view corresponding to Figure 4 of still another example of the embodiment, and is a view indicating a case in which the exhaust portion is deformed according to an increase in the pressure in the battery case. DETAILED DESCRIPTION

[0020] Hereinafter, embodiments of the present disclosure will be explained in detail with reference to the attached drawings. Further, hereinafter, in the case where a plurality of embodiments, modified examples, and the like are included, it is assumed from the beginning that a new embodiment is constructed by appropriately combining characteristic portions of the plurality of embodiments, modified examples, and the like. In addition, in a plurality of drawings, a schematic view is included, and the dimensional ratio of the depth, width, height, and the like of each member is not necessarily consistent between different drawings. In addition, among the constitutional elements explained below, a constitutional element not recorded in the independent claim indicating the most general concept is an arbitrary constitutional element, and is not necessarily a constitutional element. In addition, in the present specification, in the case where a word such as "approximately" is used, it is used in the same meaning as a word such as "about", and if it is substantially the same, the necessary condition of "approximately" is satisfied.

[0021] ​​Furthermore, in the following embodiments, the battery pack 10 is described as having a generally rectangular shape. In the accompanying drawings and descriptions of the embodiments, the X direction represents the depth direction of the battery pack 10 (battery housing 12), the Y direction represents the width direction of the battery pack 10 (battery housing 12), and the Z direction represents the height direction of the battery pack 10 (battery housing 12). The X, Y, and Z directions are orthogonal to each other.

[0022] First, refer to Figures 1 to 3 A brief overview of battery pack 10 is provided. Figure 1 This is a perspective view of a battery pack as an example of an implementation method. Figure 2 It is along Figure 1 A top sectional view observed in the AA direction (a sectional view cut by the XZ plane passing through the center of the width direction of the battery pack 10). Figure 3 It is along Figure 1 The front sectional view observed in the BB direction (a sectional view cut through the secondary battery 16 with the YZ plane in the depth direction of the battery pack 10). The battery pack 10 can be used as a power source for various electrical devices, for example, it can also be a small-capacity battery pack for smaller, portable devices such as personal computers (PCs) and electric vacuum cleaners.

[0023] The battery pack 10 includes a battery casing 12. The shape of the battery casing 12 is not particularly limited, for example... Figure 1 As shown, the battery casing 12 can also be approximately rectangular in shape. The battery casing 12 is made of, for example, metal or resin. The battery casing 12 serves to protect the rechargeable battery 16 housed inside from dust and water.

[0024] The battery casing 12 has a vent 14, which discharges gas from the secondary battery 16 to the outside of the battery casing 12. The location, number, and size of the vent 14 are not particularly limited; for example, ... Figure 1 As shown, an exhaust vent 14 may also be provided on a portion of one side of the battery housing 12 in the depth direction. Furthermore, the size of the exhaust vent 14 is sufficient to allow gas discharged from the secondary battery 16 to escape, thereby preventing the battery housing 12 from cracking. Details will be described later; however, the exhaust vent 14 functions to seal the interior of the battery housing 12 under normal conditions, and to deform and open in abnormal conditions due to increased pressure inside the battery housing 12. This prevents dust and water from entering the battery housing 12 and also prevents the battery housing 12 from cracking.

[0025] The battery pack 10 can also have a cover member 15 that covers the exhaust portion 14. Thus, the secondary batteries 16 housed in the battery case 12 can be more reliably protected from dust and water. The cover member 15 is fixed to the battery case 12 in a manner that blocks the exhaust portion 14, for example, by an adhesive or the like. The cover member 15 can also be composed of a gas-permeable and water-repellent material such as GORE-TEX (registered trademark) or the like, for example, through which exhaust gas from the inside of the battery case 12 passes and through which liquid such as water from the outside is blocked.

[0026] The battery pack 10 has secondary batteries 16 housed in a battery case 12. The number, shape, size, and the like of the secondary batteries 16 are not particularly limited, and, as shown in Figure 2 , for example, a plurality of cylindrical secondary batteries 16 can be housed in the battery case 12 in the battery pack 10. As the secondary batteries 16, a nonaqueous electrolyte secondary battery such as a lithium ion battery can be used, for example. The secondary batteries 16 can each have a positive terminal 16a and a negative terminal 16b at both ends in the depth direction. The secondary batteries 16 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 closes an opening of the outer can with an insulating gasket. The outer can can be electrically connected to the negative electrode of the electrode group, and the electrically conductive sealing plate can be electrically connected to the positive electrode. Furthermore, a current collecting member such as a metal plate is connected to the positive terminal 16a and the negative terminal 16b of the secondary battery 16, and a connection terminal that connects the outside of the positive electrode and the outside of the negative electrode is provided in the battery case 12, but the current collecting member, the connection terminal, and the like are omitted in Figure 2 .

[0027] As shown in Figure 3 , in the battery case 12, a housing portion 22 that houses the secondary batteries 16 can be provided in the inner space of the inner wall 20 formed in the periphery. An exhaust passage 18 that allows high-temperature gas discharged from the secondary batteries 16 to flow in the event of an abnormal situation is formed between the housing portions 22 and between the housing portion 22 and the inner wall 20. The exhaust passage 18 can be a passage for the gas discharged from the secondary batteries 16, and the gas is cooled by mixing with air in the exhaust passage 18 as it flows through the exhaust passage 18. For example, in Figure 2 , in a case where the sealing plate on the positive terminal 16a side of the secondary battery 16 is designed to be broken before the outer can, high-temperature gas discharged from the secondary battery 16 passes through the exhaust passage 18 for a long distance before reaching the exhaust portion 14, and thus the temperature of the gas can be effectively reduced. Furthermore, the outer can can be designed to be broken, and it is preferable that the outer can be designed to be broken after the sealing plate is broken.

[0028] As shown in Figure 3As shown, the battery casing 12 can also be divided into two half-casings 12a and 12b in the height direction. By overlapping the half-casings 12a and 12b in a relative position, the secondary battery 16 can be completely covered. In the half-casings 12a and 12b, only the top ends of the inner walls 20 abut each other, while the top ends of the other parts besides the inner walls 20 are spaced apart and opposite each other, thus forming a space within the battery casing 12, which becomes the exhaust passage 18.

[0029] Next, refer to Figures 4 to 7 The exhaust section 14 will be described in detail.

[0030] Figure 4 This is an enlarged view of a portion of the exhaust section 14 in one embodiment. The exhaust section 14 has at least one or more slits 30, such as... Figure 4 As shown, it is preferable to have a plurality of slits 30. Each slit 30 is a thin line extending through the exhaust portion 14 along its thickness direction. Furthermore, the slits 30 may not extend the entire length, or they may not extend partially. The width of the slits 30 is, for example, 5 μm to 2 mm, preferably 30 μm to 1 mm. Additionally, the thickness of the exhaust portion 14 is not particularly limited if it is such that the slits 30 can open under abnormal conditions, as described later.

[0031] like Figure 4 As shown, the slits 30 may also have the same shape, each with a sharp bend 30a and 30b, and be arranged such that the bends 30a and 30b face the same direction longitudinally and their directions alternately oppose each other transversely. By making the bends 30a and 30b of the slits 30 sharp, the covering member 15 can break when the slits 30 partially open, as described later, making it easier for gas to be discharged from the exhaust portion 14. Additionally, as... Figure 4 As shown, multiple slits 30 can also overlap laterally. The larger the overlap width w, the more the opening can be significantly enlarged relative to the pressure within the battery housing 12 under abnormal conditions.

[0032] The exhaust vent 14 has a slit 30, whereby the slit 30 is preferentially deformed in conjunction with the deformation of the exhaust vent 14 caused by the increase in pressure inside the battery housing 12. Therefore, when gas is discharged from the secondary battery 16, the pressure inside the battery housing 12 increases, and the exhaust vent 14 is pressed from the inside of the battery housing 12, thereby partially opening the slit 30, allowing gas to be discharged from the exhaust vent 14 to the outside.

[0033] Figure 5 It is along Figure 4 A cross-sectional view observed in the CC direction. Figure 5 (a) indicates the normal state where the pressure inside the battery casing 12 is low. Figure 5(b) indicates the abnormal condition where the pressure inside the battery casing 12 increases. Additionally, Figure 5 (c) is under abnormal conditions where the pressure inside the battery casing 12 increases along the path Figure 4 A cross-sectional view observed along the DD direction. For example... Figure 5 As shown in (a), the exhaust portion 14 is generally flat under normal conditions, and the width of the slits 30 at the bends 30a and 30b is narrowed to a degree that can prevent dust and water from entering the interior of the battery casing 12. However, as Figure 5 As shown in (b), under abnormal conditions, the vent 14 is subjected to pressure from inside the battery casing 12, the slit 30 is pressed outward, and the width of the slit 30 at the bends 30a and 30b widens, allowing the gas g discharged from the secondary battery 16 to be released. This suppresses the rupture of the battery casing 12. Furthermore, for the plurality of slits 30, the bending directions of the bends in each adjacent column are opposite, thus... Figure 5 (b) Figure 5 As shown in (c), the direction of gas g discharge can be different in each adjacent column of slit 30, thereby reducing the concentration of gas g outside the exhaust section 14 and reducing the risk of gas g combustion.

[0034] Preferably, the slit 30 operates reversibly according to the pressure inside the battery housing 12, for the venting section 14. That is, preferably, the slit 30 returns to its normal position when the pressure inside the battery housing 12 decreases due to the venting of gas. Thus, a sealed state can be maintained again after venting, thereby suppressing the continued burning of the secondary battery 16 caused by the inflow of external air.

[0035] Preferably, the exhaust section 14 is made of aluminum or stainless steel. This prevents the exhaust section 14 from being corroded by gases emitted from the secondary battery 16, thus ensuring stable operation. Furthermore, aluminum and stainless steel are easily elastically deformable, allowing for a wider range of deformation that enables the exhaust section 14 to operate reversibly.

[0036] Next, refer to Figure 6 Other examples of exhaust section 14 will be described. Figure 6 (a)~ Figure 6 (e) represents another example of the implementation method and Figure 4 The corresponding diagram.

[0037] exist Figure 6 In (a), the slits 300 are all of the same shape with sharp bends, and are arranged in such a way that the bends face the same direction in the longitudinal direction and their directions are alternately opposite in the transverse direction. In addition, the plurality of slits 300 do not overlap in the transverse direction.

[0038] existFigure 6 In (b), the slits 302 are of the same shape, each having a rounded curved portion 30a and 30b, and are arranged such that the curved portions face the same direction longitudinally and their directions alternately oppose each other transversely. Furthermore, the slits 302 do not overlap transversely. Figure 6 of (a), Figure 6 As shown in (b), when the slits do not overlap laterally, the exhaust portion 14 is less prone to deformation and can therefore easily operate reversibly according to the pressure inside the battery housing 12.

[0039] exist Figure 6 In (c), straight slits 304 of equal length facing two mutually orthogonal directions are arranged periodically, thereby forming a lattice-like pattern from the aggregate of slits 304. In this case, as... Figure 5 In the abnormal situation shown in (b), the exhaust direction of gas g is likely to be consistent in the same direction. However, if the concentration of gas g outside the exhaust section 14 is low enough and the risk of gas g combustion is small, the exhaust section 14 may also have such an assembly of slits 304.

[0040] exist Figure 6 In (d), the slits 306 are straight lines of the same length extending laterally, and are arranged such that their ends are aligned in the longitudinal direction and their heights in the longitudinal direction are aligned every other column in the transverse direction. In addition, the plurality of slits 306 overlap in the transverse direction.

[0041] exist Figure 6 In (e), the slits 308 are all straight lines of equal length extending laterally, arranged such that their ends are aligned longitudinally and their heights are aligned every other column laterally. Furthermore, the slits 308 do not overlap laterally. Figure 6 (d) Figure 6 As shown in (e), when slits 306 and 308 are straight lines, slits can be made relatively easily.

[0042] also, Figure 4 and Figure 6 (a)~ Figure 6 Taking the slit shown in (e) as an example, the exhaust section 14 can also have slits of various shapes.

[0043] Next, refer to Figure 7 Another example of the exhaust section 14 will be described. Figure 7 This is yet another example of the implementation method. Figure 4 The corresponding diagram shows the deformation of the exhaust section 14 due to the increase in pressure within the battery casing 12. Figure 7In the middle, the drawing shows the exhaust portion 14 in the normal state. In the exhaust portion 14, a plurality of slits 310 are formed in the longitudinal direction and the lateral direction, respectively, the pattern formed by the slits 310 is 90° rotationally symmetrical, is axially symmetrical in the up-down direction, and is axially symmetrical in the left-right direction. When the pressure in the battery case 12 rises, the exhaust portion 14 deforms as in the middle drawing and the lower drawing, and an opening is formed, so that the gas discharged from the secondary battery 16 can be exhausted. The exhaust portion 14 having Figure 7 The exhaust portion 14 of the illustrated structure can expand the opening of the slits 310, and can reversibly operate.

[0044] BRIEF DESCRIPTION OF REFERENCE NUMERALS

[0045] 10, battery pack; 12, battery case; 12a, 12b, half case; 14, exhaust portion; 15, covering member; 16, secondary battery; 18, exhaust passage; 20, inner wall; 22, accommodation portion; 30, 300, 302, 304, 306, 308, 310, slit; 30a, 30b, 30c, 30d, bent portion.

Claims

1. A battery pack, wherein, The battery pack includes: Secondary batteries; as well as A battery casing that houses the secondary battery. The battery casing has a vent, which discharges the gas emitted from the secondary battery to the outside of the battery casing. The vent has a plurality of slits that open in response to deformation of the vent as the pressure inside the battery casing increases. The width of each slit is 5μm to 2mm. For the exhaust section, the plurality of slits reversibly operate according to the pressure inside the battery casing.

2. The battery pack according to claim 1, wherein, The exhaust section is made of aluminum or stainless steel.

3. The battery pack according to claim 1 or 2, wherein, The slit is straight.

4. The battery pack according to claim 1 or 2, wherein, The slit has a curved section.

5. The battery pack according to claim 1 or 2, wherein, Multiple slits overlap.

6. The battery pack according to claim 1 or 2, wherein, The battery pack also includes a covering member that covers the exhaust section.

7. The battery pack according to claim 6, wherein, The covering component is made of a breathable and waterproof material.

Images