Battery

Abstract

The invention provides a battery provided with a gas discharge mechanism. The gas discharge mechanism can improve the gas discharge capability without increasing the size of the gas discharge mechanism. In a battery provided with a gas discharge mechanism for discharging gas inside a battery container when the gas pressure inside the battery container reaches a predetermined value, the gas discharge mechanism is provided with: a first gas discharge passage (51) connected to the inside side of the battery container; a second gas discharge passage (52) connected to the first gas discharge passage and to the outside of the battery container; and a gas discharge valve which is provided in a portion of a gas discharge passage formed by the first gas discharge passage and the second gas discharge passage, and which, when the gas pressure on the inner side of the battery container reaches a predetermined value, opens so as to connect the inner side and the outer side of the battery container through the gas discharge passage, and further opens so as to close the inner side and the outer side of the battery container when the gas pressure on the inner side of the battery container reaches the predetermined value. The cross-sectional shape of the second gas discharge passage (52) is formed so as not to hinder the flow of a streamline of the gas discharged from the first gas discharge passage (51) when viewed from the direction in which the gas is discharged when the gas discharge valve (54) is opened.

Description

Technical Field

[0001] The present invention relates to batteries. Background Art

[0002] In recent years, lithium-ion secondary batteries with high energy density have been developed as power sources for electric vehicles and hybrid vehicles. The lithium-ion secondary battery, for example, includes a wound electrode body and a battery can for storing the wound electrode body. The battery can includes a box-shaped container with one surface as an opening, i.e., an outer body, and a battery cover that blocks the opening of the outer body. In addition, in order to improve safety, a gas exhaust mechanism is provided on the battery cover of the lithium-ion secondary battery.

[0003] The gas discharge mechanism is a battery component having a discharge valve, and the discharge valve is designed to be opened due to a preset pressure when gas is generated in the battery can, thereby discharging the gas in the battery can. For example, the lithium-ion secondary battery described in Japanese Patent Publication No. 2012-252809 (Patent Document 1) has: a base forming an upper surface; a peripheral wall forming a recessed portion recessed from the base; and a cover member (battery cover) connected to the inner peripheral surface of the peripheral wall and supported, and formed integrally with the cleavage type gas discharge valve (safety valve).

[0004] In Patent Document 1, a concave portion is formed by stamping an aluminum flat plate, and a thin film-shaped gas discharge valve is integrally formed at the bottom of the concave portion. Then, when the gas pressure reaches a predetermined value, the thin film forming the gas discharge valve ruptures and releases the gas pressure to the outside, thereby ensuring safety. Prior art literature Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2012-252809 Summary of the invention Problem that the invention aims to solve

[0006] As described above, the battery used in the lithium ion secondary battery is provided with a gas discharge mechanism for the purpose of releasing the gas pressure to improve safety even when the internal electrolyte or active material is decomposed to generate gas and the internal pressure rises.

[0007] However, in such lithium-ion secondary batteries, mobile or mounted battery utilization equipment is used. For example, in the case of batteries used in electric vehicles (BEV / Battery Electric Vehicle), the battery capacity per unit is large, and as the unit size increases, the components (electrode group, electrolyte, active material, etc.) per unit also increase. Therefore, it is necessary to improve the gas discharge capacity of the gas discharge mechanism so as to be able to cope with the situation where the amount of gas generated due to the increase in components also increases.

[0008] In order to improve the gas discharge capacity of the gas discharge mechanism, it is also considered to increase the size of the gas discharge mechanism. On the other hand, it is necessary to develop a lithium ion secondary battery with a gas discharge mechanism that can improve the gas discharge capacity without increasing the size of the gas discharge mechanism.

[0009] The present embodiment described below can also be applied to batteries other than lithium-ion secondary batteries. Furthermore, the present embodiment described below can also be applied to mounted battery-utilizing equipment other than automobiles (for example, household or business-use power storage equipment).

[0010] An object of the present invention is to provide a battery having a gas exhaust mechanism capable of improving gas exhaust capability. Technical means of solving problems

[0011] The present invention is characterized in that it comprises an electric storage element, a battery container for storing the electric storage element, and a gas exhaust mechanism, wherein the gas exhaust mechanism fluidically connects the inner side of the battery container and the outer side of the battery container, and exhausts the gas inside the battery container when the gas pressure inside the battery container reaches a specified value, and the gas exhaust mechanism comprises: a first gas exhaust passage connected to the inner side of the battery container; a second gas exhaust passage connected to the first gas exhaust passage and connected to the outer side of the battery container; and a gas exhaust valve disposed closer to the second gas exhaust passage than the inner side end of the battery container of the first gas exhaust passage. On the outlet flow path side or a part of the gas exhaust passage that is closer to the first gas exhaust flow path side than the outer end of the battery container of the second gas exhaust passage, when the gas pressure inside the battery container reaches a specified value, an opening action is performed to connect the inner side and the outer side of the battery container through the gas exhaust passage, and when the opening action is performed, it is opened into a shape along the cross-sectional shape of the gas exhaust passage, and further, the cross-sectional shape of the second gas exhaust passage observed from the outflow direction of the gas when the gas exhaust valve is opened is formed into a shape that does not hinder the flow of the streamline of the gas flowing out of the first gas exhaust passage. Effects of the Invention

[0012] According to the present invention, it is possible to provide a battery including a gas exhaust mechanism capable of improving gas exhaust capability. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is an external perspective view showing the external appearance of a lithium ion secondary battery. Figure 2 This is an exploded perspective view of a lithium-ion secondary battery disassembled to show its constituent parts. Figure 3 It is a cross-sectional view showing a cross section of a gas exhaust mechanism for explaining the concept of the present invention. Figure 4A It is a cross-sectional view showing the structure of the gas exhaust mechanism according to the first embodiment of the present invention. Figure 4B It is a cross-sectional view showing the structure of a gas exhaust mechanism according to a first modified example of the first embodiment. Figure 4C It is a cross-sectional view showing the structure of a gas exhaust mechanism according to a second modified example of the first embodiment. Figure 5 It is a cross-sectional view showing the types of parameters used for performing the simulation of the gas exhaust mechanism of FIG. 4 . Fig. 6A It is an explanatory diagram showing parameter values ​​when executing the simulation of the gas exhaust mechanism according to the first embodiment. Figure 6B It is an explanatory diagram showing the simulation results when the simulation of the gas exhaust mechanism according to the first embodiment is executed. Fig. 7A It is an explanatory diagram showing parameter values ​​when a simulation is performed while changing the plate thickness of the battery cover of the gas discharge mechanism according to the first embodiment. Figure 7B It is an explanatory diagram showing simulation results when the simulation is performed while changing the plate thickness of the battery cover of the gas discharge mechanism according to the first embodiment. Figure 8 It is a cross-sectional view showing the structure of a gas exhaust mechanism according to a second embodiment of the present invention. Fig. 9 It is used to carry out Figure 8 A cross-sectional diagram of the types of parameters of the simulation of the gas exhaust mechanism. Fig. 10A It is an explanatory diagram showing parameter values ​​when executing the simulation of the gas exhaust mechanism according to the second embodiment. Fig. 10B It is an explanatory diagram showing the simulation results when the simulation of the gas exhaust mechanism according to the second embodiment is executed. Fig.11 It is a cross-sectional view showing the structure of a gas exhaust mechanism according to a third embodiment of the present invention. Fig.12 It is a cross-sectional view showing the structure of a gas exhaust mechanism according to a fourth embodiment of the present invention. Fig.13 It is used to carry out Fig.12 A cross-sectional diagram of the types of parameters of the simulation of the gas exhaust mechanism. Fig.14A It is an explanatory diagram showing parameter values ​​when performing a simulation of the gas exhaust mechanism according to the fourth embodiment. Fig. 14B It is an explanatory diagram showing simulation results when a simulation of the gas exhaust mechanism according to the fourth embodiment is performed. Fig.15 It is a cross-sectional view showing the structure of a gas exhaust mechanism according to a fifth embodiment of the present invention. Fig.16 It is a cross-sectional view showing the structure of a gas exhaust mechanism according to a sixth embodiment of the present invention. Fig.17 This is a perspective view of an appearance of a battery having a structure applicable to the present invention, which is disassembled and viewed from obliquely above. DETAILED DESCRIPTION

[0014] Hereinafter, embodiments of the present invention will be described in detail using the drawings, but the present invention is not limited to the following embodiments, and various modifications and application examples are also included in the technical concept of the present invention. Example 1

[0015] The embodiments of the present invention are described using the drawings. In the following embodiments, a lithium ion secondary battery used in a hybrid vehicle or an electric vehicle is described as an example of a battery. Figure 1 The external appearance of a general lithium ion secondary battery to which the present embodiment is applied is shown when viewed obliquely from above.

[0016] like Figure 1 As shown in FIG. 1 , the lithium-ion secondary battery C1 includes a battery can 1 and a cover member (hereinafter referred to as a battery cover) 6. These are collectively referred to as a "battery container". In addition, a wound electrode body 3 (see FIG. 1 ) serving as an "electricity storage element" for outputting stored electricity is housed in the battery can 1 having an opening. Figure 2 ), the opening 1a of the battery can 1 (refer to Figure 2 ) is sealed by a battery cover 6. For example, an electrolyte is contained in the battery can 1, and the wound electrode body 3 is immersed in the electrolyte. Alternatively, an electrolyte other than a liquid electrolyte such as a solid electrolyte may be used.

[0017] The battery cover 6 is joined to the battery can 1 by laser welding, and a battery container is formed by the battery can 1 and the battery cover 6. A positive electrode external terminal 8A and a negative electrode external terminal 8B are provided on the battery cover 6. The lithium ion secondary battery C1 charges the wound electrode body 3 via the positive electrode external terminal 8A and the negative electrode external terminal 8B, and supplies power to an external load.

[0018] The battery cover 6 is integrally provided with a gas discharge mechanism 10. When the gas pressure in the battery container rises to a predetermined pressure for some reason, the gas discharge valve of the gas discharge mechanism 10 is opened to discharge the gas from the inside. Thus, the gas pressure in the battery container is reduced, and the safety of the lithium-ion secondary battery C1 is ensured. In addition, the battery cover 6 is provided with a liquid injection port 9 (see Figure 2 ) is formed to be sealed by the injection plug 11 after the electrolyte is injected.

[0019] The gas exhaust mechanism 10 connects the internal side of the battery container and the external side of the battery container by fluid. Fluid connection means that when the gas exhaust valve 54 is opened, the fluid (gas or liquid) in the space between the internal side and the external side of the battery container separated by the gas exhaust valve 54 (see FIG. 4 ) can flow. Although an example in which the gas exhaust mechanism 10 is integrally provided on the battery cover 6 is described, the structure of the gas exhaust mechanism 10 can also be manufactured separately and arranged on the battery cover 6.

[0020] Figure 2 It means that when viewed from above, Figure 1 The lithium-ion secondary battery shown in the figure has a disassembled appearance.

[0021] The battery can 1 of the lithium-ion secondary battery C1 is a so-called square shape, and has a rectangular can bottom 22, a square cylindrical side wall portion (sometimes also referred to as a side peripheral surface) 21 rising from the four sides of the can bottom 22 in the battery cell height direction (+Y direction), and an opening portion 1a opened in the battery cell height direction at the upper end of the side wall portion 21. The side wall portion 21 of the battery can 1 has a pair of wide side wall portions 21a separated and opposed to each other in the battery cell thickness direction (+Z direction) and a pair of narrow side wall portions 21b separated and opposed to each other in the battery cell width direction (+X direction).

[0022] The wound electrode body 3 is contained in the battery can 1 in a state of being wrapped and covered by the insulating protective film 2. The wound electrode body 3 has a substantially rectangular flat shape, having a pair of flat surfaces, and a pair of curved surfaces with arc-shaped cross sections that are opposite to each other across the pair of flat surfaces. The wound electrode body 3 is inserted into the battery can 1 from one curved surface side, and is contained in the battery can 1 in a lateral posture state with the winding axis direction along the width direction of the battery cell (+X direction). In addition, the wound electrode body 3 may also use a stacked electrode body instead of a wound electrode body. The electrode body comprises a positive electrode having a positive electrode material and a negative electrode having a negative electrode material.

[0023] At least a portion of the positive electrode foil connection portion 31d and the negative electrode foil connection portion 32d, which are the exposed portions of the electrode foil of the wound electrode body 3, are bundled into a flat plate shape in the flat thickness direction, and are joined to the positive electrode side connection end 42A of the positive electrode collector plate (collector terminal) 4A and the negative electrode side connection end 42B of the negative electrode collector plate (collector terminal) 4B by ultrasonic welding, respectively.

[0024] The base ends of the positive collector plate 4A and the negative collector plate 4B are connected to the positive external terminal 8A and the negative external terminal 8B, respectively. A gasket 5 and an insulating plate 7 are provided on the battery cover 6 to electrically insulate the positive collector plate 4A and the negative collector plate 4B and the positive external terminal 8A and the negative external terminal 8B from the battery cover 6, respectively.

[0025] Aluminum or aluminum alloy is used as a metal material for the battery can 1 and the battery cover 6. Aluminum or aluminum alloy is used as a material for the positive electrode collector plate 4A and the positive electrode external terminal 8A. Copper or copper alloy is used as a material for the negative electrode collector plate 4B and the negative electrode external terminal 8B.

[0026] The positive external terminal 8A and the negative external terminal 8B have a welded joint portion welded to a busbar (not shown) etc. The welded joint portion has a rectangular block shape protruding upward from the battery cover 6, and is arranged so that the lower surface is opposite to the surface of the battery cover 6 and the upper surface is parallel to the battery cover 6 at a predetermined height position.

[0027] The positive electrode connection portion 12A and the negative electrode connection portion 12B protrude from the lower surface of the positive electrode external terminal 8A and the negative electrode external terminal 8B, respectively, and have a cylindrical shape whose top end can be inserted into the positive electrode side through hole 6A and the negative electrode side through hole 6B of the battery cover 6. The positive electrode connection portion 12A and the negative electrode connection portion 12B penetrate the battery cover 6 and protrude further to the inner side of the battery can 1 than the positive electrode collector plate base 41A and the negative electrode collector plate base 41B of the positive electrode collector plate 4A and the negative electrode collector plate 4B. The top end is riveted to fix the positive electrode external terminal 8A and the negative electrode external terminal 8B, the positive electrode collector plate 4A and the negative electrode collector plate 4B to the battery cover 6 as a whole.

[0028] A gasket 5 is interposed between the positive electrode external terminal 8A, the negative electrode external terminal 8B and the battery cover 6 , and an insulating plate 7 is interposed between the positive electrode collector plate 4A, the negative electrode collector plate 4B and the battery cover 6 .

[0029] The positive collector plate 4A and the negative collector plate 4B have: a rectangular plate-shaped positive collector plate base 41A and a negative collector plate base 41B, which are arranged opposite to the lower surface of the battery cover 6; and a positive side connecting end 42A and a negative side connecting end 42B, which are bent at the side ends of the positive collector plate base 41A and the negative collector plate base 41B, extend along the wide side surface of the battery can 1 toward the can bottom 22 side, and are connected in a state of being opposite to and overlapping with the positive foil connecting portion 31d and the negative foil connecting portion 32d of the wound electrode body 3.

[0030] The positive current collector plate base 41A and the negative current collector plate base 41B are respectively formed with a positive electrode side opening hole 43A and a negative electrode side opening hole 43B through which the positive electrode connecting portion 12A and the negative electrode connecting portion 12B pass.

[0031] The positive electrode side terminal component is formed by the above-mentioned positive electrode external terminal 8A and the positive electrode collector plate 4A, and the negative electrode side terminal component is formed by the negative electrode external terminal 8B and the negative electrode collector plate 4B. In addition, these positive electrode side terminal component and negative electrode side terminal component are integrally assembled on the battery cover 6 via the gasket 5 and the insulating plate 7, thereby forming a battery cover assembly. In addition, by assembling the wound electrode body 3 on the battery cover assembly, the storage element assembly is assembled.

[0032] The wound electrode body 3 is supported between the positive electrode collector plate 4A and the negative electrode collector plate 4B of the battery cover assembly, with the winding axis extending parallel to the battery cover 6 and the flat surface extending in a direction perpendicular to the lower surface of the battery cover 6. A pair of curved surfaces of the wound electrode body 3 are separately arranged on one side of the battery cover 6 and on the side of the bottom 22 of the battery can 1.

[0033] The insulating protective film 2 covers the wound electrode body 3 assembled on the battery cover assembly together with the positive electrode collector plate 4A and the negative electrode collector plate 4B from the outside, and is interposed between the side wall portion 21 and the bottom 22 in the battery can 1 .

[0034] The insulating protective film 2 is made of an insulating synthetic resin material, and insulates the battery can 1 from the wound electrode body 3, the positive electrode collector plate 4A, and the negative electrode collector plate 4B. In addition, it protects the wound electrode body 3, the positive electrode collector plate 4A, and the negative electrode collector plate 4B so that when an impact or vibration acts on the lithium-ion secondary battery C1 from the outside, the wound electrode body 3, the positive electrode collector plate 4A, and the negative electrode collector plate 4B do not directly contact the battery can 1.

[0035] The battery can 1 has such a size and shape that when the wound electrode body 3 is inserted into the battery can 1 from the opening 1a in a state where the insulating protective film 2 covers the periphery of the wound electrode body 3, the pair of flat surfaces of the wound electrode body 3 and the wide side wall portion 21a of the side wall portion 21 of the battery can 1 abut with the insulating protective film 2 sandwiched therebetween, and can be inserted by pushing with a certain pushing force. In addition, a certain gap is formed between the end surfaces on both sides of the winding axis direction of the wound electrode body 3 and the narrow side wall portion 21b of the side wall portion 21 of the battery can 1.

[0036] As described above, the opening 1a of the battery can 1 is closed by the battery cover 6, and the battery cover 6 is laser welded to the battery can 1 to be sealed. Then, the battery can 1 is filled with an electrolyte. The electrolyte is injected into the battery can 1 from the injection port 9 of the battery cover 6. The injection port 9 is closed by the injection plug 11 after the electrolyte is injected, and the injection plug 11 is laser welded to the battery cover 6 to be sealed.

[0037] In a lithium-ion secondary battery having the above structure, for example, a battery for BEV, the battery capacity of each battery cell is large, and as the cell size increases, the components such as the electrode group, electrolyte, and active material of each cell also increase. Therefore, due to the increase in components, the amount of gas generated during thermal runaway of the battery cell also increases, so it is necessary to improve the gas discharge capacity of the gas discharge mechanism.

[0038] In order to improve the gas discharge capability of the gas discharge mechanism, the size of the gas discharge mechanism can be increased, but the area occupied by the gas discharge mechanism of the battery container will be greatly increased.

[0039] Therefore, it is necessary to develop a lithium ion secondary battery equipped with a gas exhaust mechanism that can improve the gas exhaust capability without increasing the size of the gas exhaust mechanism. Therefore, in this embodiment, the following configuration is proposed.

[0040] In the present embodiment, the gas exhaust mechanism provided on the battery cover comprises: a first gas exhaust passage connected to the inner side of the battery container; a second gas exhaust passage connected to the first gas exhaust passage and to the outer side of the battery container; a gas exhaust valve provided in the first gas exhaust passage, which opens when the gas pressure inside the battery container reaches a specified value to connect the first gas exhaust passage and the second gas exhaust passage, and opens into a shape along the cross-sectional shape of the gas exhaust passage when performing the opening action, and further, the cross-sectional shape of the second gas exhaust passage observed from the outflow direction of the gas when the gas exhaust valve is opened is formed into an inclined shape that does not hinder the flow of the streamline of the gas flowing out of the first gas exhaust passage.

[0041] According to this embodiment, since the streamline of the outflowing gas is not blocked by the second gas exhaust passage, the gas can flow smoothly, and the gas exhaust capability can be improved. In addition, the opening shape (cross-sectional shape of the passage) of the gas exhaust passage is described below as a circular shape.

[0042] Figure 3 This is a diagram for explaining the basic concept of the present embodiment, schematically showing the configuration of the gas exhaust mechanism and the flow of gas. In addition, in the following drawings including this figure, the plate thickness (t) of the battery cover 6 forming the gas exhaust path and the opening diameter (d) of the gas exhaust path are not the correct dimensional relationship, but the plate thickness (t) is drawn larger.

[0043] exist Figure 3In the embodiment, the battery cover 6 has a plate thickness (t), and a gas exhaust passage 50 is formed in the plate thickness direction (a direction orthogonal to the surface and back of the battery cover). In addition, the gas exhaust valve is omitted. The gas exhaust passage 50 is composed of a first gas exhaust passage 51 connected to the fluid of the inner side (SPin) of the battery container and a second gas exhaust passage 52 connected to the fluid of the first gas exhaust passage 51 and connected to the fluid of the outer side (SPout) of the battery container.

[0044] Here, fluid connection means that when the gas exhaust valve is opened, the fluid (gas or liquid) in the space inside and outside the battery container separated by the gas exhaust valve can flow through the first gas exhaust passage 51 and the second gas exhaust passage 52 .

[0045] The cross-sectional shape of the passage including the openings of the first gas exhaust passage 51 and the second gas exhaust passage 52 (in the direction perpendicular to the plate thickness direction) is circular, and the first gas exhaust passage 51 and the second gas exhaust passage 52 are formed on the same axis. Therefore, the outlet opening of the first gas exhaust passage 51 and the inlet opening of the second gas exhaust passage 52 have the same opening diameter and are connected so as to overlap.

[0046] The first gas exhaust passage 51 is formed in a cylindrical shape (actually a space, also called a cylindrical shape) in the plate thickness direction, and the second gas exhaust passage 52 is formed in a truncated cone shape (actually a space, also called a truncated cone tube shape) in the plate thickness direction. In addition, the connection portion of the first gas exhaust passage 51 and the second gas exhaust passage 52 has the same opening diameter (d). Here, as shown in the figure, as it approaches the outer side (SPout) of the battery container, the opening diameter (d) of the second gas exhaust passage continuously increases, and the cross-sectional shape observed from the gas outflow direction is formed into a linearly inclined inclined portion 53 that expands in a direction away from the axis of the second gas exhaust passage 52.

[0047] Next, the behavior of the gas flowing through the first gas discharge passage 51 and the second gas discharge passage 52 will be described. As shown by the gas streamline (FLW), after the gas generated inside the battery container flows into the first gas discharge passage 51, a contraction flow portion (ACF) is formed in the middle of the first gas discharge passage 51, and then flows out from the first gas discharge passage 51, expanding in a manner that expands outward. In particular, the streamline on the outer peripheral side has a strong tendency to expand outward. In addition, the gas streamline shown here is a hypothetical representation of the flow of the gas based on the streamline in fluid mechanics.

[0048] Moreover, as the gas exhaust passage of the gas exhaust mechanism as a comparative example relative to the present embodiment, as shown by the dotted line (DL), it is formed into a shape that extends the first gas exhaust passage 51, and the flow of the streamline of the expanded gas is hindered in this part, and there is a tendency that the gas exhaust amount is suppressed. This is because the streamline is disturbed in the area of ​​the dotted line (DL). In addition, the so-called obstruction of the flow of the streamline refers to the phenomenon that the gas flowing outside the airflow is hindered by other physical obstacles (here, the passage wall of the gas exhaust passage), forming a vortex and cannot flow smoothly, and the streamline is disturbed.

[0049] Therefore, in the present embodiment, in order not to disturb the direction of the streamline of the gas flowing out of the first gas discharge passage 51, the opening diameter (d) of the second gas discharge passage 52 is gradually increased as it approaches the outside side (SPout) of the battery container. That is, the cross-sectional shape viewed from the gas outflow direction is formed into an inclined portion 53 that is inclined in a direction away from the axis of the second gas discharge passage 52. The inclined portion 53 is formed in a shape that does not hinder the flow of the streamline of the gas flowing out from the first gas discharge passage 51 to the second gas discharge passage 52.

[0050] Here, the shape that does not hinder the flow of streamlines refers to a shape that does not hinder the flow of gas flowing outside the gas flow and allows the gas to flow smoothly. In other words, the shape is formed so that the streamlines of the gas outside the gas flow do not contact or collide with other obstacles (here, the passage wall of the gas exhaust passage).

[0051] Thus, the gas flowing out of the first gas discharge passage 51 can flow out smoothly without being disturbed as in the conventional configuration, and the gas discharge amount can be prevented from being suppressed. Thus, the battery cover 6 can be made lighter and a sufficient gas discharge amount can be ensured.

[0052] Next, the specific structure of the first embodiment will be described. Figure 3 The gas discharge mechanism shown in FIG. 4 is provided with a gas discharge valve. As described above, the plate thickness (t) of the battery cover 6 forming the gas discharge path and the opening diameter (d) of the gas discharge path are not in the correct dimensional relationship, but the plate thickness (t) is drawn larger. Figure 3 The same reference numerals denote the same configurations, and thus their repeated descriptions are omitted here.

[0053] In Fig. 4, a gas discharge valve 54 is press-fitted into the first gas discharge passage 51 side of the connection portion between the first gas discharge passage 51 and the second gas discharge passage 52. The gas discharge valve 54 includes a pressure receiving surface 55 for receiving the pressure of the gas, and a pressing surface 56 formed integrally with the pressure receiving surface 55. The pressing surface 56 is pressed into the inner peripheral wall surface of the first gas discharge passage 51. The opening period of the gas discharge valve 54 can be adjusted according to the relationship between the pressing force, the area of ​​the pressure receiving surface, and the gas pressure.

[0054] In addition, unlike the gas exhaust valve 54 that is pressed in, the gas exhaust valve 54 can be formed integrally with the battery cover 6 on the first gas exhaust passage 51 side of the connection portion between the first gas exhaust passage 51 and the second gas exhaust passage 52. That is, the gas exhaust valve 54 is a thin-walled membrane portion that crosses in a manner to close the first gas exhaust passage 51, and the thin-walled membrane portion is formed integrally with the battery cover 6. Moreover, the opening period of the gas exhaust valve 54 can be adjusted according to the thickness of the membrane portion.

[0055] In addition, an example is shown in which at least a portion of the gas discharge passage 51 that reaches the gas discharge valve 54 has a flow path having an area (or opening diameter) substantially the same as an area (or opening diameter) of the gas discharge flow path 51 side of the gas discharge valve 54. For example, the area (or opening diameter) of the opening portion of the inlet opening 51in of the first gas flow path 51 is substantially the same as the area of ​​the gas discharge valve 54. Alternatively, the inlet opening 51in has a flow path portion having a larger area (or opening diameter) than the gas discharge valve 54, and the main portion of the first gas flow path 51 on the gas discharge valve 54 side is substantially the same area (or opening diameter) as the area (or opening diameter) of the first discharge flow path side of the gas discharge valve 54.

[0056] Here, it is important that the gas discharge valve 54 does not disturb the gas flow line as much as possible when it is opened. In the existing split type, the flow line is often disturbed when it is opened. Therefore, in this embodiment, the gas discharge valve 54 is a valve that flies out of the gas discharge passage 51 and detaches when it is opened. The state of the gas discharge valve 54 detaching is Figure 3 That is, when the gas exhaust valve 54 is opened, it opens to a shape along the cross-sectional shape of the gas exhaust passage.

[0057] Furthermore, when the gas pressure inside the battery container reaches a predetermined value for some reason, the gas discharge valve 54 overcomes the pressing force and flies out due to the gas pressure, and is separated from the battery cover 6. Here, the predetermined value of the gas pressure at which the gas discharge valve 54 is separated is the gas pressure at which the gas discharge valve 54 opens as a safety valve before the internal gas of the battery container reaches a pressure that causes the battery container to break. The predetermined value is appropriately selected according to the strength of the battery container, etc.

[0058] In addition, instead of the press-fit type gas discharge valve 54 shown in FIG4 , a gas discharge valve composed of a thin-walled membrane portion may be integrally formed on the battery cover 6 by machining as described above. That is, a membrane portion thinner than the plate thickness of the battery cover 6 is integrally formed on a portion of the first gas discharge passage 51 as the gas discharge valve 54.

[0059] As shown in the figure, if the gas exhaust valve 54 is formed on the first gas exhaust passage 51 side including the boundary portion connecting the first gas exhaust passage 51 and the second gas exhaust passage 52, the gas exhaust valve 54 can be formed by machining. Thus, the gas exhaust valve 54 can be a thin-walled membrane portion formed integrally with the battery cover 6.

[0060] Furthermore, the pressure-receiving surface of the membrane portion of the gas discharge valve 54 is not uniformly thick, but is formed into an annular thin-walled portion that is thinner than the central portion on the side connected to the wall surface of the first gas discharge passage 51. For example, an annular groove is formed along the peripheral end of the pressure-receiving surface. Thus, when gas pressure is applied, the membrane portion of the gas discharge valve 54 is ruptured in a circular shape from the annular groove, and the pressure-receiving surface is cleanly peeled off.

[0061] Alternatively, a side-opening gas exhaust valve with somewhat disordered streamlines may be used. For example, a configuration in which a groove is not formed on a portion of the peripheral end portion where the annular groove is formed. Since the non-grooved portion of the annular groove does not peel off and remains during cracking, the pressure-bearing surface of the membrane portion becomes side-opening.

[0062] In this way, when the gas exhaust valve 54 is opened, it opens into a shape along the cross-sectional shape of the gas exhaust passage.

[0063] In addition, the gas discharge valve 54 can be formed by mechanical processing as described above. For example, the first gas discharge passage 51 as a cylindrical space is formed by cutting, and the second gas discharge passage 52 composed of the inclined portion 53 is formed by cutting, so that the gas discharge valve 54 can be formed at the boundary portion. Alternatively, the gas discharge valve 54 can be formed by stamping (drawing using a punch and a die).

[0064] Figure 4B The first modified example of the first embodiment is shown, and the gas exhaust valve 54 is formed by a press working. In this case, the second gas exhaust passage 52 is formed by a punch, and the first gas exhaust passage 51 is formed by a die, so that the film-shaped gas exhaust valve 54 is formed integrally with the battery unit 6 at the boundary portion. Here, since the axial cross section of the first gas exhaust passage 51 is a straight tube shape, and the axial cross section of the second gas exhaust passage 52 is a trapezoidal shape, the gas exhaust passages 51 and 52 of the necessary shapes can be formed by using a die and a punch of a contoured shape.

[0065] in addition, Figure 4C The second modified example is shown, which also forms the gas exhaust valve 54 by press working. In this case, the second gas exhaust passage 52 is formed by a punch, and the first gas exhaust passage 51 is formed by a die, so that the film-like gas exhaust valve 54 is formed integrally with the battery unit 6 at the boundary portion.

[0066] Here, since the axial cross section of the first gas exhaust passage 51 is a trapezoid, and the axial cross section of the second gas exhaust passage 52 is a trapezoid, the connecting portion of the first gas exhaust passage 51 and the second gas exhaust passage 52 becomes the narrowest passage, and a film-like gas exhaust valve 54 is formed in this portion. Therefore, by using a die and a punch of a contoured shape, the gas exhaust passages 51 and 52 can be formed in a necessary shape.

[0067] In addition, from the viewpoint of uniformity of the flow of the gas discharge, it is preferable that the axis C of the first gas discharge passage 51 and the second gas discharge passage 52 be the same axis.

[0068] Furthermore, when the gas exhaust valve 54 is disengaged, Figure 3 In the manner shown, the streamline of the gas flowing out of the first gas discharge passage 51 can be smoothly discharged without being disturbed as in the conventional configuration, and the gas discharge amount can be prevented from being suppressed. Thus, the battery cover 6 can be made lightweight and a sufficient gas discharge amount can be ensured. In this case, when the gas discharge valve 54 is opened, it is also opened to a shape along the cross-sectional shape of the gas discharge passage.

[0069] Next, the influence of the inclined portion 53 formed in the second gas discharge passage 52 will be described. The influence of the inclined portion 53 on the streamline of the outer peripheral side of the gas flow was confirmed by simulation, and an example thereof will be briefly described below. In addition, the gas discharge passages 51, 52 and the gas discharge valve 54 of the battery cover 6 used in the following simulation are Figure 4B The form shown as the first variant example.

[0070] The parameters used in the simulated gas flow model are Figure 5 The thickness (t) of the battery cover 6 forming the gas exhaust path, the arrangement length (l) of the gas exhaust valve 54, the opening diameter (din) of the inlet opening 51in of the first gas exhaust passage 51, and the inclination angle (θ) of the inclined portion 53 are shown. In addition, the thickness (t) of the battery cover 6, the arrangement length (l) of the gas exhaust valve 54, and the inlet opening diameter (din) of the first gas exhaust passage 51 are fixed values, and the simulation is performed with the inclination angle (θ) of the inclined portion 53 as a variable.

[0071] The results are shown in Fig. 6. As shown in Fig. 6, the inlet opening diameter (din) of the first gas exhaust passage 51 is 5 mm, the plate thickness (t) of the battery cover 6 forming the gas exhaust path is 2 mm, the configuration length (l) of the gas exhaust valve 54 is 1 mm, and the inclination angle (θ) of the inclined portion 53 is used as a variable.

[0072] In addition, the "inclination angle (θ) = 0°" on the vertical axis of the graph of FIG. 6 is Figure 3 The dashed line (DL) shown corresponds to the outlet opening when the first gas exhaust passage 51 is extended. In addition, the gas flow rate is the flow rate of the outlet opening 52out of the second gas exhaust passage 52, and the influence of the change in the inclination angle (θ) is expressed as a ratio to the flow rate when the inclination angle (θ) = 0.

[0073] As can be seen from the graph of FIG. 6 , the larger the inclination angle (θ) of the inclined portion 53, the larger the flow ratio. This means that the larger the flow ratio, the greater the gas flow rate. In particular, it can be seen that the gas flow rate increases when the inclination angle (θ) is 55°. Therefore, in actual design, if the inclination angle (θ) is set to 55° or more, the gas flow rate can be effectively increased.

[0074] Furthermore, near an inclination angle of 60°, a flow ratio of 110% can obtain substantial effects. Preferably, the inclination angle is 60° or more. In addition, near an inclination angle of 75°, a flow ratio of 120% can obtain significant effects. In order to exhaust gas more effectively, the inclination angle is preferably 60° or more.

[0075] In addition, if the inclination angle (θ) is increased, the plate thickness (t) of this part becomes thinner, and the mechanical strength decreases. Therefore, from the perspective of mechanical strength, it is necessary to select an inclination angle (θ) that can ensure sufficient plate thickness (t). This can be determined as the design specification of the battery.

[0076] Next, Fig. 7 shows simulation results when the thickness (t) of the battery cover 6 forming the gas exhaust path is changed. The parameters are the same as those in Fig. 6, and the results are shown when the thickness (t) of the battery cover 6 is changed to 0.2 mm, 2 mm, and 10 mm.

[0077] As can be seen from Fig. 7, even at the same inclination angle (θ), the greater the plate thickness (t), the greater the gas flow rate. In actual design, if the plate thickness (t) is set larger, the gas flow rate can be effectively increased.

[0078] Compared to the inlet opening diameter (din) of the first gas exhaust passage 51, the plate thickness (t) of the portion of the battery cover 6 forming the gas exhaust path is preferably 40% or more of the length of the inlet opening diameter (din). More preferably, the plate thickness (t) of the portion of the battery cover 6 forming the gas exhaust path is more than twice the length of the inlet opening diameter (din).

[0079] However, if the plate thickness (t) is increased, the weight of the battery cover 6 will increase, so from the viewpoint of weight, it is necessary to select a battery cover 6 having a necessary plate thickness (t). This can be determined as a design specification of the battery.

[0080] In the case where the thickness of the battery cover 6 is not desired to be thickened, for example, the thickness (t) of the battery cover 6 forming the gas exhaust mechanism 10 (gas exhaust path) is made thicker than the surrounding of the gas exhaust mechanism 10. In the case where the gas exhaust mechanism 10 is mounted on the battery cover 6 (the gas exhaust mechanism 10 and the battery cover 6 are not an integral structure but a separate structure), the thickness setting becomes easy, so it is preferred. In addition, for example, the first gas exhaust passage 51 and the second gas exhaust passage 52 have an opening with a circular cross-section. The axis of the first gas exhaust passage 51 and the second gas exhaust passage 52 are common (the same axis). In other embodiments, in addition to the embodiment in which the structure is changed, the same structure may also be provided.

[0081] Thus, in the present embodiment, the gas exhaust mechanism provided on the battery cover 6 comprises: a first gas exhaust passage 51 connected to the inner side (SPin) of the battery container; a second gas exhaust passage 52 connected to the first gas exhaust passage 51 and to the outer side (SPout) of the battery container; and a gas exhaust valve 54 provided in the first gas exhaust passage 51, and when the gas pressure inside the battery container reaches a prescribed value, an opening action is performed to connect the first gas exhaust passage 51 and the second gas exhaust passage 52, and further, a cross-sectional shape of the second gas exhaust passage 52 observed from the outflow direction of the gas when the gas exhaust valve 54 is opened is formed into an inclined shape that does not hinder the flow of the streamline of the gas flowing out of the first gas exhaust passage 51.

[0082] According to the present embodiment, since the streamline of the outflowing gas is not blocked by the second gas discharge passage 52 , the gas can flow smoothly, and the gas discharge capability can be improved.

[0083] In addition, the formation position of the gas exhaust mechanism 10 is not limited to the battery cover 6, and the gas exhaust mechanism 10 can also be provided on any one of the battery containers that accommodate the storage element. Therefore, it can also be applied to the case where the battery container does not have a battery cover 6. In the present embodiment, the gas exhaust mechanism 10 is provided on the battery cover 6 formed with the positive electrode external terminal 8A and the negative electrode external terminal 8B. As in the present embodiment, since the gas exhaust mechanism 10 is provided on the battery cover 6 having a predetermined thickness and a predetermined rigidity, a highly reliable valve opening action can be obtained. In the case where the gas exhaust valve 54 is formed integrally with the battery container, it is also easy to form.

[0084] In this embodiment, the gas discharge valve 54 is formed at a position that enters the second gas flow path 52 from the end of the inlet opening 51in side of the first gas passage 51. Therefore, a stable gas flow passes through the gas discharge valve, which is preferable. Example 2

[0085] Next, the second embodiment of the present invention is described. In the first embodiment, the cross-sectional shape of the second gas exhaust passage 52 is the inclined portion 53 formed by straight lines, but in the second embodiment, the cross-sectional shape of the second gas exhaust passage 52 is the convex arc-shaped portion 57. Figure 8 As shown, the arc portion 57 is at the corner of the outlet opening 52out ( Figure 3 The portion indicated by the dotted line (DL) forms a rounded structure, and in this embodiment, a structure referred to as "R" in mechanical drawing is adopted.

[0086] That is, the cross-sectional shape of the second gas exhaust passage 52 is formed such that the opening diameter of the second gas exhaust passage 52 gradually increases continuously as it approaches the outside side (SPout) of the battery container, and the cross-sectional shape observed from the outflow direction of the gas is formed into an arc (arc-shaped portion 57) that expands at a predetermined radius in the direction away from the axis of the second gas exhaust passage 52. (Here, in the present embodiment, an arc is illustrated as an example of an arc-shaped shape, but a shape other than an arc may also be used. In addition, since the arc-shaped portion 57 is illustrated as an arc in the present embodiment, it is hereinafter marked as the arc-shaped portion 57). Furthermore, the arc-shaped portion 57 is composed of a convex arc protruding toward the axis (C) side. The arc-shaped portion 57 is formed into a shape that does not hinder the flow of the streamline of the gas flowing out from the first gas exhaust passage 51 to the second gas exhaust passage 52.

[0087] exist Figure 8In the embodiment, a gas discharge valve 54 is pressed into the first gas discharge passage 51 side of the connection portion between the first gas discharge passage 51 and the second gas discharge passage 52. The position of the gas discharge valve 54 depends on the arc radius (r). That is, if the arc radius (r) is long, the press-in position of the gas discharge valve 54 is close to the inlet opening 51in side, and if the arc radius (r) is short, the press-in position of the gas discharge valve 54 is away from the inlet opening 51in side.

[0088] The gas discharge valve 54 includes a pressure-receiving surface 55 for receiving the pressure of the gas and a pressing surface 56 formed integrally with the pressure-receiving surface 55. The pressing surface 56 is pressed into the inner peripheral wall surface of the first gas discharge passage 51. The opening timing of the gas discharge valve 54 can be adjusted according to the relationship between the pressing force, the area of ​​the pressure-receiving surface, and the gas pressure.

[0089] Here, it is important that the gas discharge valve 54 does not disturb the gas flow line as much as possible when it is opened. In the existing cleavage type, the flow line is often disturbed when it is opened. Therefore, in this embodiment, the gas discharge valve 54 uses a valve in a manner that flies out of the gas discharge passage 51 and detaches when it is opened.

[0090] Furthermore, when the pressure of the gas in the battery container reaches a predetermined value for some reason, the gas discharge valve 54 overcomes the pressing force and flies out due to the pressure of the gas, and is detached from the battery cover 6. When the gas discharge valve 54 is detached, the streamline of the gas flowing out from the first gas discharge passage 51 flows along the arc portion 57. In this way, the streamline of the gas will not be disturbed as in the previous structure, and it can flow out smoothly, and the gas discharge amount can be avoided from being suppressed. As a result, the battery cover 6 can be lightweight and a sufficient gas discharge amount can be ensured.

[0091] Next, the influence of the arc portion 57 formed in the second gas discharge passage 52 will be described. It has been confirmed through simulation that the arc portion 57 has an influence on the streamline on the outer peripheral side of the flow of gas, and an example thereof will be briefly described below.

[0092] The parameters used in the simulated gas flow model are Fig. 9 The thickness (t) of the battery cover 6 of the portion forming the gas discharge path, the arrangement length (l) of the gas discharge valve 54, the inlet opening diameter (din) of the inlet opening portion 51in of the first gas discharge passage 51, and the arc radius (r) of the arc portion 57 are shown. In addition, the thickness (t) of the battery cover 6 and the inlet opening diameter (din) of the first gas discharge passage 51 are constant fixed values, and the arc radius (r) of the arc portion 57 is used as a variable for simulation. In addition, since the arrangement length (l) of the gas discharge valve 54 depends on the arc radius (r), it is calculated each time.

[0093] The results are shown in Fig. 10. As shown in Fig. 10, the inlet opening diameter (din) of the first gas exhaust passage 51 is 5 mm, the plate thickness (t) of the battery cover 6 forming the gas exhaust passage is 2 mm, and the arc radius (r) of the arc portion 57 is used as a variable.

[0094] In addition, "arc radius (r) = 0.001 mm" on the vertical axis of the graph of Fig. 10 is the arc radius of the corner of the outlet opening when the first gas discharge passage 51 indicated by the dotted line (DL) shown in Fig. 4 is extended. In addition, the gas flow rate is the flow rate of the outlet opening 52out of the second gas discharge passage 52, and the influence of the change in the arc radius (r) is expressed as a ratio to the flow rate when the arc radius (r) = 0.001 mm.

[0095] As can be seen from the curve graph of FIG10 , the larger the arc radius (r) of the arc portion 57, the larger the flow ratio. This means that the larger the flow ratio, the more the gas flow rate increases. In particular, it can be seen that the gas flow rate increases when the arc radius (r) is 1 mm. Therefore, in actual design, if the arc radius (r) is set based on the curve of FIG10 , the gas flow rate can be effectively increased.

[0096] The convex arc-shaped flow path may not be limited to a correct circular shape. For example, the flow path may be a flow path of the following shape, that is, in the plate thickness (t) direction of the second gas discharge passage 52, compared with the change Δd1 of the opening diameter d (in the direction orthogonal to t) from the first position (referred to as t1) to the position (t1+Δt) on the side of the outlet opening 52out of the degree Δt, the change Δd2 of the opening diameter d (in the direction orthogonal to t) from the second position (referred to as t2) to the position (t2+Δt) on the side of the outlet opening 52out of the degree Δt is greater, and the second position is located on the side of the outlet opening 52out relative to the first position.

[0097] For example, the arc portion 57 is preferably formed larger than half in the plate thickness (t) direction of the battery cover 6 forming the gas exhaust path. Specifically, the second gas exhaust path 52 is longer than the first gas exhaust path 51 .

[0098] Thus, in the present embodiment, the gas exhaust mechanism provided on the battery cover 6 comprises: a first gas exhaust passage 51 connected to the inner side (SPin) of the battery container; a second gas exhaust passage 52 connected to the first gas exhaust passage 51 and to the outer side (SPout) of the battery container; and a gas exhaust valve 54 provided in the first gas exhaust passage 51, and when the gas pressure inside the battery container reaches a prescribed value, an opening action is performed to connect the first gas exhaust passage 51 and the second gas exhaust passage 52, and further, a cross-sectional shape of the second gas exhaust passage 52 observed from the outflow direction of the gas when the gas exhaust valve 54 is opened is formed into a convex arc shape that does not hinder the flow of the streamline of the gas flowing out of the first gas exhaust passage 51.

[0099] According to the present embodiment, since the streamline of the outflowing gas is not blocked by the second gas discharge passage 52 , the gas can flow smoothly, and the gas discharge capability can be improved. Example 3

[0100] The third embodiment of the present invention is described below. In the second embodiment, the cross-sectional shape of the second gas exhaust passage 52 is a convex arc-shaped portion 57, but in the third embodiment, the cross-sectional shape of the second gas exhaust passage 52 is a concave arc-shaped portion 58. Fig.11 As shown, the arc portion 58 is a corner portion ( Figure 3 The structure is formed by cutting the thickness of the portion indicated by the dotted line (DL) into an arc shape with a specified radius (r).

[0101] That is, the cross-sectional shape of the second gas exhaust passage 52 is formed such that the opening diameter of the second gas exhaust passage 52 continuously and gradually increases as it approaches the outer side (SPout) of the battery container, and the cross-sectional shape observed in the outflow direction of the gas is formed into an arc (arc-shaped portion 58) that expands with a prescribed radius in a direction away from the axis of the second gas exhaust passage 52 (here, in the present embodiment, a circular arc is illustrated as an example of an arc-shaped shape, but it may also be a shape other than a circular arc. In addition, since the arc-shaped portion 58 is illustrated as an arc in the present embodiment, it is hereinafter labeled as the circular arc portion 58). The arc portion 58 is formed of a concave arc away from the axis (C) side. The arc portion 58 has a shape that does not hinder the flow of the streamline of the gas flowing out from the first gas discharge passage 51 to the second gas discharge passage 52 .

[0102] exist Fig.11In the embodiment, a gas discharge valve 54 is pressed into the first gas discharge passage 51 side of the connection portion between the first gas discharge passage 51 and the second gas discharge passage 52. The position of the gas discharge valve 54 depends on the arc radius (r). That is, if the arc radius (r) is long, the press-in position of the gas discharge valve 54 is close to the inlet opening 51in side, and if the arc radius (r) is short, the press-in position of the gas discharge valve 54 is away from the inlet opening 51in side.

[0103] The gas discharge valve 54 includes a pressure-receiving surface 55 for receiving the pressure of the gas and a pressing surface 56 formed integrally with the pressure-receiving surface 55. The pressing surface 56 is pressed into the inner peripheral wall surface of the first gas discharge passage 51. The opening timing of the gas discharge valve 54 can be adjusted according to the relationship between the pressing force, the area of ​​the pressure-receiving surface, and the gas pressure.

[0104] Here, it is important that the gas discharge valve 54 does not disturb the gas flow line as much as possible when it is opened. In the existing cleavage type, the flow line is often disturbed when it is opened. Therefore, in this embodiment, the gas discharge valve 54 is a valve that flies out from the first gas discharge passage 51 and detaches when it is opened.

[0105] Furthermore, when the pressure of the gas in the battery container reaches a predetermined value for some reason, the gas discharge valve 54 overcomes the pressing force and flies out due to the pressure of the gas, and is detached from the battery cover 6. When the gas discharge valve 54 is detached, the streamline of the gas flowing out from the first gas discharge passage 51 flows along the arc portion 58. In this way, the streamline of the gas will not be disturbed as in the previous structure, and it can flow out smoothly, and the gas discharge amount can be avoided from being suppressed. As a result, the battery cover 6 can be lightweight and a sufficient gas discharge amount can be ensured.

[0106] The concave arc-shaped flow path may not be limited to a correct circular shape. For example, the flow path may be a flow path of the following shape, that is, in the plate thickness (t) direction of the second gas discharge passage 52, compared with the change Δd1 of the opening diameter d from the first position (referred to as t1) to the position (t1+Δt) on the outlet opening 52out side of the degree Δt, the change Δd2 of the opening diameter d (in the direction orthogonal to t) from the second position (referred to as t2) to the position (t2+Δt) on the outlet opening 52out side of the degree Δt is smaller, and the second position is located on the outlet opening 52out side relative to the first position.

[0107] Thus, in the present embodiment, the gas exhaust mechanism provided on the battery cover 6 comprises: a first gas exhaust passage 51 connected to the inner side (SPin) of the battery container; a second gas exhaust passage 52 connected to the first gas exhaust passage 51 and to the outer side (SPout) of the battery container; and a gas exhaust valve 54 provided in the first gas exhaust passage 51, and when the gas pressure inside the battery container reaches a prescribed value, an opening action is performed to connect the first gas exhaust passage 51 and the second gas exhaust passage, and further, a cross-sectional shape of the second gas exhaust passage 52 observed from the outflow direction of the gas when the gas exhaust valve 54 is opened is formed into a concave arc shape that does not hinder the flow of the streamline of the gas flowing out of the first gas exhaust passage 51.

[0108] According to the present embodiment, since the streamline of the outflowing gas is not blocked by the second gas discharge passage 52 , the gas can flow smoothly, and the gas discharge capability can be improved. Example 4

[0109] The fourth embodiment of the present invention is described below. In the first to third embodiments, the cross-sectional shape of the passage of the second gas exhaust passage 52 is the inclined portion 53, the convex arc portion 57 and the concave arc portion 58, but in the fourth embodiment, the cross-sectional shape of the passage of the second gas exhaust passage 52 is different in that the large diameter portion 59 is stepped relative to the first gas exhaust passage 51.

[0110] As an example of a portion forming a stepped shape, the large diameter portion 59 is Fig.12 The large diameter portion 59 is a cylindrical shape (actually a space, which can also be called a cylindrical shape), and the outlet opening diameter (dout) is formed larger than the inlet opening diameter (din) of the first gas exhaust passage 51 (see FIG. 14). The large diameter portion 59 is formed in a shape that does not hinder the flow of the streamline of the gas flowing out from the first gas exhaust passage 51 to the second gas exhaust passage 52.

[0111] exist Fig.12 In the embodiment, the first gas discharge passage 51 is formed in a cylindrical shape (actually a space, also referred to as a cylindrical shape) in the plate thickness direction, and the second gas discharge passage 52 is also formed in a cylindrical shape (actually a space, also referred to as a cylindrical shape) in the plate thickness direction. A gas discharge valve 54 is press-fitted into the first gas discharge passage 51 side of the connection portion between the first gas discharge passage 51 and the second gas discharge passage 52.

[0112] The gas discharge valve 54 includes a pressure-receiving surface 55 for receiving the pressure of the gas and a pressing surface 56 formed integrally with the pressure-receiving surface 55. The pressing surface 56 is pressed into the inner peripheral wall surface of the first gas discharge passage 51. The opening timing of the gas discharge valve 54 can be adjusted according to the relationship between the pressing force, the area of ​​the pressure-receiving surface, and the gas pressure.

[0113] Furthermore, when the pressure of the gas in the battery container reaches a predetermined value for some reason, the gas discharge valve 54 overcomes the pressing force and flies out due to the pressure of the gas, and is detached from the battery cover 6. When the gas discharge valve 54 is detached, the streamline of the gas flowing out of the first gas discharge passage 51 flows to the second gas discharge passage 52 having a large outlet opening diameter (dout), so that the gas can flow out smoothly without being disturbed as in the prior art structure, and the gas discharge amount can be avoided from being suppressed. Thus, the battery cover 6 can be lightweight and a sufficient gas discharge amount can be ensured.

[0114] Next, the influence of the large diameter portion 59 formed in the second gas discharge passage 52 will be described. It has been confirmed through simulation that the large diameter portion 59 has an influence on the streamline on the outer peripheral side of the flow of gas, and an example thereof will be briefly described below.

[0115] The parameters used in the simulated gas flow model are Fig.13 The thickness (t) of the battery cover 6 forming the gas exhaust path, the arrangement length (l) of the gas exhaust valve 54, the opening diameter (din) of the inlet opening 51in of the first gas exhaust passage 51, and the opening diameter (dout) of the outlet opening 52out are shown. In addition, the thickness (t) of the battery cover 6, the arrangement length (l) of the gas exhaust valve 54, and the inlet opening diameter (din) of the first gas exhaust passage 51 are fixed values, and the simulation is performed with the outlet opening diameter (dout) of the outlet opening 52out as a variable.

[0116] The results are shown in Fig. 14. As shown in Fig. 14, the inlet opening diameter (din) of the first gas exhaust passage 51 is 5 mm, the plate thickness (t) of the battery cover 6 forming the gas exhaust path is 2 mm, the configuration length (l) of the gas exhaust valve 54 is 1 mm, and the outlet opening diameter (dout) of the second gas exhaust passage 52 is variable.

[0117] In addition, as shown by the dotted line (DL) shown in FIG4 , the "outlet opening diameter 5 mm" on the vertical axis of the graph of FIG14 corresponds to the outlet opening portion when the first gas discharge passage 51 is extended. In addition, the gas flow rate is the flow rate of the outlet opening portion 52out of the second gas discharge passage 52, and the influence of the change in the outlet opening diameter (dout) is expressed as a ratio to the flow rate when the outlet opening diameter is 5 mm.

[0118] As can be seen from the curve graph of FIG14, the larger the outlet opening diameter (dout), the larger the flow ratio. This means that the larger the flow ratio, the more the gas flow rate increases. In particular, it can be seen that the gas flow rate increases when the outlet opening diameter (dout) is limited to 7 mm. Therefore, in actual design, if the outlet opening diameter (dout) is set based on the curve graph of FIG14, the gas flow rate can be effectively increased.

[0119] The outlet opening diameter of 5 mm can be considered as the opening diameter of the side end of the first gas exhaust passage 51 of the second gas exhaust passage 52. Therefore, the outlet opening diameter (dout) is preferably greater than 1.5 times the opening diameter of the side end of the first gas exhaust passage 51 of the second gas exhaust passage 52. Furthermore, when the outlet opening diameter (dout) is 10 mm, the flow ratio is 110%, and a substantial effect can be obtained. It is preferably more than 2 times. In addition, when the outlet opening diameter (dout) is 15 mm, the flow ratio is about 120%, and a significant effect can be obtained. In order to exhaust gas more effectively, it is preferably more than 3 times.

[0120] The stepped large diameter portion may be provided with a plurality of stepped portions, for example. A structure (intermediate step) having an opening diameter larger than the opening diameter of the first gas discharge passage 51 side end of the second gas discharge passage 52 and smaller than the outlet opening diameter (dout) may also be provided between the first gas discharge passage 51 side end of the second gas discharge passage 52 and the outlet. It is easier to manufacture than an inclined shape, and the difference between adjacent opening diameters is smaller than the structure shown in the figure, so it is preferred.

[0121] Thus, in the present embodiment, the gas exhaust mechanism provided on the battery cover 6 comprises: a first gas exhaust passage 51 connected to the inner side (SPin) of the battery container; a second gas exhaust passage 52 connected to the first gas exhaust passage 51 and to the outer side (SPout) of the battery container; and a gas exhaust valve 54 provided in the first gas exhaust passage 51, and when the gas pressure inside the battery container reaches a prescribed value, an opening action is performed to connect the first gas exhaust passage 51 and the second gas exhaust passage, and further, a cross-sectional shape of the second gas exhaust passage 52 observed from the outflow direction of the gas when the gas exhaust valve 54 is opened is formed into a stepped large-diameter portion that does not hinder the flow of the streamline of the gas flowing out of the first gas exhaust passage 51.

[0122] According to the present embodiment, since the streamline of the outflowing gas is not blocked by the second gas discharge passage 52 , the gas can flow smoothly, and the gas discharge capability can be improved. Example 5

[0123] The fifth embodiment of the present invention is described below. In the fourth embodiment, the axis of the first gas exhaust passage 51 and the second gas exhaust passage 52 are common (the same axis), but in the fifth embodiment, the difference is that the axis of the first gas exhaust passage 51 and the axis of the second gas exhaust passage 52 are different axes.

[0124] like Fig.15 As shown, the first gas exhaust passage 51 and the second gas exhaust passage 52 are cylindrical (actually, they are spaces, which can also be called cylindrical), and the outlet opening diameter (dout) is larger than the inlet opening diameter (din) of the first gas exhaust passage 51. In addition, the axis (C2) of the second gas exhaust passage 52 is eccentrically formed at a predetermined distance (Δd) relative to the axis (C1) of the first gas exhaust passage 51.

[0125] In such a structure, when the pressure of the gas in the battery container reaches a predetermined value for some reason, the gas discharge valve 54 overcomes the pressing force and flies out due to the pressure of the gas, and is detached from the battery cover 6. When the gas discharge valve 54 is detached, the streamline of the gas flowing out from the first gas discharge passage 51 flows to the second gas discharge passage 52 with a large outlet opening diameter, so that it can flow out smoothly without being disturbed as in the conventional structure, and the gas discharge amount can be avoided from being suppressed. Thus, the battery cover 6 can be lightweight and a sufficient gas discharge amount can be ensured.

[0126] Thus, in the present embodiment, the gas exhaust mechanism provided on the battery cover 6 comprises: a first gas exhaust passage 51 connected to the inner side (SPin) of the battery container; a second gas exhaust passage 52 having an axis eccentric to the axis of the first gas exhaust passage 51 and connected to the first gas exhaust passage 51, and connected to the outer side (SPout) of the battery container; and a gas exhaust valve 54 provided in the first gas exhaust passage 51, and when the gas pressure inside the battery container reaches a specified value, opening action is performed to connect the first gas exhaust passage 51 and the second gas exhaust passage, and further, the cross-sectional shape of the second gas exhaust passage 52 observed from the outflow direction of the gas when the gas exhaust valve 54 is opened is formed into a stepped large-diameter portion that does not hinder the flow of the streamline of the gas flowing out of the first gas exhaust passage 51.

[0127] According to the present embodiment, since the streamline of the outflowing gas is not blocked by the second gas discharge passage 52 , the gas can flow smoothly, and the gas discharge capability can be improved.

[0128] In addition, in the first to fifth embodiments, an example in which the gas discharge valve 54 is provided in the first gas flow path 51 is shown. Among them, an example in which the gas discharge valve 54 is provided at the end of the second gas flow path side 52 of the first gas flow path 51 is shown. In addition, the gas discharge valve 54 may be provided closer to the second gas flow path side 52 than the inlet opening 51in of the first gas flow path 51, and closer to the inlet opening 51in side than the second gas flow path 52.

[0129] In addition, in the first to fifth embodiments, an example is illustrated in which the area (or opening diameter) of at least the main portion of the first gas flow path 51 or the area (or opening diameter) of the opening of the inlet opening 51in is substantially the same as the area (opening diameter) of the gas discharge valve 54. In addition, the first gas flow path 51 may be a form in which the area (or opening diameter) of the gas discharge valve 54 is smaller than the inlet opening 51in of the first gas flow path 51. Sometimes, it is easy to operate in terms of insertion and discharge of a machine for processing. In this case, from the viewpoint of gas discharge, it is preferred that the value (52out / 54) of the area (or opening diameter) of the outlet opening 51out divided by the area (or opening diameter) of the gas discharge valve 52 is larger than the value (51in / 54) of the area (or opening diameter) of the inlet opening 51in divided by the area (or opening diameter) of the gas discharge valve 52.

[0130] As an example, as described above Figure 4C As shown in the cross section, the first gas flow path 51 and the second gas flow path may not be straight lines but may have straight line slopes extending outward. Alternatively, the cross sections of the first gas flow path 51 and the second gas flow path 52 may be arc-shaped slopes. Example 6

[0131] In the first to fifth embodiments, the gas exhaust valve 54 is provided in the first gas exhaust passage 51 , but in this embodiment, the gas exhaust valve 54 is provided in the second gas exhaust passage 52 .

[0132] like Fig.16 As shown, based on the configuration of the first embodiment, a gas discharge valve 60 is provided on the second gas discharge passage 52 side when viewed from the connection portion of the first gas discharge passage 51 and the second gas discharge passage 52. As described in the first embodiment, when the gas pressure in the battery container exceeds a predetermined value, the gas discharge valve 60 is actuated to be separated from the second gas discharge passage 52.

[0133] Here, the gas discharge valve 60 is fixed to the wall surface of the second gas discharge passage 52, here, the inclined portion 53, by welding or the like. By using welding or the like in this way, the gas discharge valve 60 can be fixed at any position of the inclined portion 53.

[0134] In addition, as shown in the figure, if the gas exhaust valve 60 is formed on the second gas exhaust passage 52 side including the boundary portion connecting the first gas exhaust passage 51 and the second gas exhaust passage 52, the gas exhaust valve 60 can be formed by machining. Here, as described in the first embodiment, the gas exhaust valve 60 may be a membrane portion formed integrally with the battery cover 6.

[0135] For example, the first gas discharge passage 51 as a cylindrical space can be formed in the boundary portion by cutting, and the second gas discharge passage 52 consisting of the inclined portion 53 can be formed in the boundary portion by cutting, thereby forming the film-like gas discharge valve 60.

[0136] Alternatively, the gas discharge valve 60 may be formed by a stamping process (drawing process using a punch and a die). In this case, the second gas discharge passage 52 is formed by a punch, and the first gas discharge passage 51 is formed by a die, thereby forming a film-shaped gas discharge valve 60. Of course, the pressure-bearing surface of the film portion of the gas discharge valve 60 is not of uniform thickness, but is formed in a configuration of an annular thin-walled portion that is thinner than the vicinity of the central portion on the side connected to the wall surface of the second gas discharge passage 52, so that when gas pressure is applied, the film portion of the gas discharge valve 60 is ruptured in a circular shape from the annular groove, and the pressure-bearing surface is cleanly peeled off.

[0137] Here, since the gas discharge valve 60 is formed at the boundary portion, the inclined portion 53 functions as a taper portion of the punch, and deep drawing can be performed. In addition, if an annular groove formed by deep drawing is provided on the portion of the gas discharge valve 60 connected to the inclined portion 53, the gas discharge valve 60 can be detached as described above.

[0138] In the present embodiment, the gas discharge valve 60 can be formed so that the area (or opening diameter) on the second gas discharge passage 52 side is larger than the area (or opening diameter) on the first gas discharge passage 51 side.

[0139] In this embodiment, since the streamline of the outflowing gas is not blocked by the second gas exhaust passage, the gas can flow smoothly, and the gas exhaust capability can be improved. Fig.16 The configuration of the second to fifth embodiments is based on the configuration of the first embodiment, but the same gas exhaust valve may be provided in the configuration of the second to fifth embodiments.

[0140] In the first to sixth embodiments, the cross-sectional shape perpendicular to the axis of the gas discharge passage is circular, but the present invention is not limited thereto and may be rectangular, oval, or elliptical as long as the streamline is smoothly formed.

[0141] As described in the above embodiment, in the battery of the present invention, the gas exhaust mechanism comprises: a first gas exhaust passage, which is connected to the inner side of the battery container; a second gas exhaust passage, which is connected to the first gas exhaust passage and to the outer side of the battery container; a gas exhaust valve, which is arranged on a part of the gas exhaust passage formed by the first gas exhaust passage and the second gas exhaust passage, and when the gas pressure inside the battery container reaches a specified value, an opening action is performed to connect the inner side and the outer side of the battery container through the gas exhaust passage, and further, the cross-sectional shape of the second gas exhaust passage observed in the outflow direction of the gas when the gas exhaust valve is opened is formed into a shape that does not hinder the flow of the streamline of the gas flowing out of the first gas exhaust passage.

[0142] Thus, the streamline of the outflowing gas is not blocked by the second gas discharge passage, so the gas can flow smoothly, and the gas discharge capability can be improved.

[0143] In the above embodiment, from the viewpoint of manufacturability, the length of the first gas exhaust passage 51 in the direction of the plate thickness (t) can be formed to be 5% to 80% of the plate thickness (t) of the battery cover, and preferably 10% to 50% from the viewpoint of gas flow.

[0144] In the present embodiment, the gas discharge valve 54 is provided on a portion of the gas flow path having the first gas flow path 51 and the second gas flow path 52, and the second gas discharge path has an opening diameter larger than the opening diameter of the first gas discharge path 51. A battery having any one of the following features A to C is preferred.

[0145] A: The second gas flow path 52 is formed so that the opening diameter of the second gas exhaust path 52 gradually increases as it approaches the outside of the battery container, and the cross-sectional shape observed from the gas outflow direction has a linearly inclined inclined portion 53 extending in a direction away from the axis of the second gas exhaust path 52. B: The second gas flow path 52 is formed so that the opening diameter of the second gas exhaust passage 52 continuously and gradually increases as it approaches the outer side of the battery container, and the cross-sectional shape observed from the gas outflow direction is an arc-shaped arc portion extending in the direction away from the axis of the second gas exhaust passage 52 (for example, the arc-shaped portion is a convex arc portion in a direction protruding toward the axis side of the second gas exhaust passage 52, or the arc-shaped portion is a concave arc portion in a direction away from the axis side of the second gas exhaust passage 52). C: The second gas exhaust passage 52 is formed in a stepped shape with a large opening diameter on the outside of the battery container.

[0146] Next, a battery configuration that can efficiently introduce gas generated in the battery container into the first gas exhaust passage 51 will be briefly described. In this case, the gas exhaust mechanism 10 of the battery container is located above the battery can 1 in the gravity direction.

[0147] exist Fig.17 In the embodiment, the battery can 1 accommodates the electrode body 3 and the like surrounded by the separator 61. The battery can 1 is composed of a rectangular metal can having an opening 1a opened in the longitudinal direction and a housing portion 1b connected to the opening 1a. The battery can 1 is formed of, for example, aluminum or an aluminum alloy.

[0148] The upper end 3a of the electrode body 3 is formed on the opposite side of the bottom 22 of the battery can 1. Terminal fittings 62A and 62B are arranged at the upper end 3a. The terminal fitting 62A is electrically connected to the positive external terminal 8A, and the terminal fitting 62B is electrically connected to the negative external terminal 8B. Moreover, the electrode body 3 is stacked in the longitudinal direction (direction of gravity), and a small gap is formed between adjacent surfaces, and the gap is connected to the upper end 3a.

[0149] The battery cover 6 seals the opening 1a of the battery can 1. The battery cover 6 is formed of a long plate-shaped metal plate, and a positive electrode side insertion hole consisting of a circular through hole is formed at one end side in the longitudinal direction. The insertion portion of the positive electrode external terminal 8A is inserted into the positive electrode side insertion hole. Similarly, a negative electrode side insertion hole consisting of a circular through hole is formed on the other end side in the longitudinal direction of the battery cover 6. The insertion portion of the negative electrode external terminal 8B is inserted into the negative electrode side insertion hole.

[0150] The battery cover 6 also has a liquid injection insertion hole formed of a circular through hole between the positive electrode external terminal 8A and the negative electrode external terminal 8B. A sealing plug 11 is inserted into the liquid injection insertion hole.

[0151] Furthermore, a gas discharge mechanism 10 is formed at the center in the longitudinal direction of the battery cover 6, and the battery cover 6 is welded to the battery can 1. The battery cover 6 is formed of, for example, aluminum or an aluminum alloy. The gas discharge mechanism 10 includes the configurations of the above-mentioned embodiments.

[0152] The insulating cover 63 covers the electrode body 3, exposes the upper end 3a of the electrode body 3, and covers the portion other than the upper end 3a of the electrode body 3. The insulating cover 63 is formed in a pentahedral shape, folded into a box shape, and is formed of polypropylene, for example.

[0153] If it is a battery of the present structure, the electrode body 3 is stacked in the longitudinal direction (direction of gravity) to form a tiny gap between adjacent surfaces, and the gap is connected to the upper end 3a. Therefore, the gas generated from the electrode body 3 is smoothly guided upward in the direction of gravity to the space between the electrode body 3 and the battery cover 6, thereby being able to improve the gas discharge capacity in a small manner.

[0154] In addition, the present invention is not limited to the above-mentioned several embodiments, including various modified examples. The above-mentioned embodiments are described in detail in order to easily explain the present invention, and are not necessarily limited to the embodiments having all the described structures. In addition, the structures of other embodiments can replace part of the structures of certain embodiments, and the structures of other embodiments can be added to the structures of certain embodiments. For the structures of each embodiment, other structures can also be added, deleted, or replaced. Explanation of symbols

[0155] C1… lithium-ion secondary battery, 1… battery can, 1a… opening, 2… insulating protective film, 3… wound electrode body, 3a… flat surface on the front side, 3a… flat surface on the back side, 4A… positive electrode collector plate, 4B… negative electrode collector plate, 5… gasket, 6… battery cover, 6A… positive electrode side through hole, 6B… negative electrode side through hole, 7… insulating plate, 8A… positive electrode external terminal, 8B… negative electrode external terminal, 9… liquid injection port, 10… gas exhaust mechanism, 11… liquid injection plug, 12A… positive electrode connecting portion, 12B… negative electrode connecting portion, 50… gas exhaust passage, 51… first gas exhaust passage, 52… second gas exhaust passage, 53… inclined portion, 54… gas exhaust valve, 55… pressure receiving surface, 56… pressurized surface structure, 57… convex arc portion, 58… concave arc portion, 59… large diameter portion.

Claims

1. A battery comprising an electric storage element, a battery container for accommodating the electric storage element, and a gas exhaust mechanism, wherein the gas exhaust mechanism fluidically connects the inside of the battery container and the outside of the battery container, and exhausts the gas inside the battery container when the gas pressure inside the battery container reaches a predetermined value, wherein the battery is characterized in that: The gas exhaust mechanism comprises: a first gas exhaust passage connected to the interior side of the battery container; a second gas exhaust passage connected to the first gas exhaust passage and connected to the outside of the battery container; and a gas exhaust valve provided on a portion of the gas exhaust passage which is closer to the second gas exhaust passage side than the inner end of the battery container of the first gas exhaust passage or closer to the first gas exhaust passage side than the outer end of the battery container of the second gas exhaust passage, and which performs an opening action when the gas pressure inside the battery container reaches a predetermined value so as to connect the inner side and the outer side of the battery container through the gas exhaust passage, and which opens into a shape along the passage cross-sectional shape of the gas exhaust passage when performing the opening action, The cross-sectional shape of the second gas discharge passage as viewed in the outflow direction of the gas when the gas discharge valve is open is formed into a shape that does not hinder the flow of a streamline of the gas flowing out of the first gas discharge passage.

2. The battery according to claim 1, characterized in that The gas exhaust valve is provided on the first gas exhaust passage side.

3. The battery according to claim 2, characterized in that The gas exhaust valve is provided on the first gas exhaust passage side including a boundary of a connection portion between the first gas exhaust passage and the second gas exhaust passage.

4. The battery according to claim 1, characterized in that The gas exhaust valve is provided on the second gas exhaust passage side.

5. The battery according to claim 4, characterized in that The gas exhaust valve is provided on the second gas exhaust passage side including a boundary of a connection portion between the first gas exhaust passage and the second gas exhaust passage.

6. The battery according to claim 3 or claim 5, characterized in that: The battery container includes: a battery can having an opening and accommodating the electric storage element, and a battery cover sealing the battery can. The battery cover includes a positive external terminal and a negative external terminal for supplying electric power from the electric storage element to the outside, and the gas exhaust passage. The gas exhaust valve is a membrane portion formed integrally with the battery cover, and a thin-walled annular groove is formed in a portion of the membrane portion that is connected to the wall surface of the gas exhaust passage.

7. The battery according to claim 2 or claim 4, characterized in that: The cross-sectional shape of the second gas exhaust passage is: The opening diameter of the second gas discharge passage increases gradually as it approaches the outside of the battery container, and the cross-sectional shape viewed in the gas outflow direction has a linearly inclined portion extending in a direction away from the axis of the second gas discharge passage.

8. The battery according to claim 2 or claim 4, characterized in that: The cross-sectional shape of the second gas exhaust passage is: The opening diameter of the second gas discharge passage increases gradually as it approaches the outside of the battery container, and the cross-sectional shape viewed from the gas outflow direction is an arc-shaped portion extending in a direction away from the axis of the second gas discharge passage.

9. The battery according to claim 8, characterized in that The arc-shaped portion is a convex arc portion that protrudes in a direction toward the axial line side of the second gas exhaust passage.

10. The battery according to claim 8, characterized in that The arc-shaped portion is a concave arc portion in a direction away from the axial line side of the second gas exhaust passage.

11. The battery according to claim 2 or claim 4, characterized in that: The first gas exhaust passage and the second gas exhaust passage are cylindrical spaces. The second gas discharge passage has an opening diameter larger than an opening diameter of the first gas discharge passage, and the second gas discharge passage is formed in a step shape by the larger opening diameter.

12. The battery according to claim 11, characterized in that The first gas exhaust passage and the second gas exhaust passage have the same axis.

13. The battery according to claim 11, characterized in that The axes of the first gas exhaust passage and the second gas exhaust passage are eccentric axes.

14. The battery according to claim 11, characterized in that The gas exhaust mechanism includes a gas exhaust valve, The gas exhaust valve is arranged on a part of the gas exhaust passage formed by the first gas exhaust passage and the second gas exhaust passage, and when the gas pressure inside the battery container reaches a specified value, an opening action is performed to connect the inner side and the outer side of the battery container through the gas exhaust passage, and when the opening action is performed, the gas exhaust valve opens into a shape along the cross-sectional shape of the gas exhaust passage.

15. The battery according to claim 2 or claim 4, characterized in that: The gas exhaust valve is a valve that is separated from the first gas exhaust passage when opened.

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