Electricity storage device

Abstract

The invention provides an electricity storage device which can maintain high air tightness and appropriately prevent external air from flowing back into a housing after a valve is opened or prevent the inside of the housing from communicating with the outside. A power storage device (1, 11, 21, 31, 41) is provided with: a case (4, 14, 24, 34, 44) made of metal; and an electrode body (2) housed in the case, the case having a combination valve section (7, 17, 27, 37, 47), the combination valve section comprising: a non-return safety valve section (5, 35), the valve opening pressure of which is a first valve opening pressure (POs); and a non-return mechanism (6, 16, 26, 36, 46) which is disposed in series with the relief valve section, which closes the valve by a decrease in the internal pressure (PIc) of the housing after the release of the gas (GS) due to the opening of the relief valve section and the non-return mechanism, and which prevents the inflow of external gas (AR) from the outside of the housing into the housing, said non-return mechanism having an open valve pressure that is a second open valve pressure (POr) that is lower than the first open valve pressure, the non-return mechanism closing the valve by a decrease in the internal pressure (PIc) of the housing after the release of the gas (GS) due to the opening of the relief valve section and the non-return mechanism.

Description

Technical Field

[0001] This invention relates to an energy storage device equipped with a safety valve. Background Technology

[0002] Secondary batteries using a resettable safety valve, as in Patent Document 1, are known. On the other hand, secondary batteries using a non-resettable safety valve, as in Patent Document 2, are also known.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2007-59145

[0006] Patent Document 2: Japanese Patent Application Publication No. 2023-88663 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] In secondary batteries using reset-type safety valves, internal gas is released each time the internal pressure of the housing increases, thus preventing abnormal pressure rises. However, reset-type safety valves are difficult to maintain a complete airtight seal between the valve and seat for an extended period. Additionally, adhesion or contamination between the valve and seat can sometimes prevent maintaining the same opening pressure for extended periods.

[0009] On the other hand, in secondary batteries using non-resettable safety valves, high airtightness can be maintained when the valve is closed. Furthermore, it is easy to maintain a constant opening pressure for the safety valve. However, once a non-resettable safety valve is opened, it cannot close. Therefore, after the valve is opened, external gas flows back into the housing through the open safety valve, or the housing remains connected to the outside while the battery interior is exposed to external gas, which is not preferable.

[0010] The present invention was made in view of the current situation and provides an energy storage device that can maintain high airtightness while appropriately preventing external gas from flowing back into the housing or becoming a state of communication between the inside and outside of the housing after the valve is opened.

[0011] Solution for solving the problem

[0012] (1) One aspect of the present invention for solving the above-mentioned problem is an energy storage device, the energy storage device comprising: a housing made of metal; and an electrode body housed within the housing, wherein the housing has a composite valve section, the composite valve section comprising: a non-resettable safety valve section, the opening pressure of the safety valve section being a first opening pressure; and a check mechanism, the check mechanism being configured in series with the safety valve section, the opening pressure being a second opening pressure lower than the first opening pressure, wherein the check mechanism closes the valve by reducing the internal pressure of the housing after the release of gas caused by the opening of the safety valve section and the check mechanism, thereby preventing external gas from flowing into the housing from the outside of the housing.

[0013] This energy storage device has a composite valve section including a non-resettable safety valve section and a check mechanism arranged in series therewith. Therefore, in the event of an increase in internal pressure due to some reason, both the non-resettable safety valve section and the check mechanism open. This allows gas inside the housing to be released to the outside through the open safety valve section and check mechanism, safely reducing the internal pressure. Furthermore, when the gas release ends and the pressure difference between the internal pressure of the housing and atmospheric pressure is lower than the second opening pressure, the non-resettable safety valve section remains open, but the check mechanism closes. This prevents external gas from flowing back into the housing from the outside. Additionally, it prevents a state where the inside and outside of the housing remain connected.

[0014] In addition, examples of energy storage devices include nickel-metal hydride (Ni-MH) batteries, lithium-ion batteries, sodium-ion batteries, and capacitors such as lithium-ion capacitors. Furthermore, the metal used to construct the casing can be selected based on factors such as the electrolyte used in the energy storage device; for example, aluminum and stainless steel are suitable choices.

[0015] The composite valve section includes a non-resettable safety valve section and a check mechanism configured in series with the safety valve section. The safety valve section and the check mechanism are configured in series such that the gas discharge path is set so that gas inside the housing is released to the outside through one of the safety valve section and the check mechanism after opening, and then through the other. Here, the non-resettable safety valve section refers to a safety valve section that opens when the differential pressure between the inside and outside reaches a first opening pressure, and remains open after opening, not returning to its original closed state even if the differential pressure decreases. The check mechanism is configured to open when the differential pressure between the inside and outside reaches a second opening pressure, and return to its original closed state when the differential pressure decreases to a level lower than the second opening pressure, while simultaneously preventing backflow from the outside to the inside. For example, a check valve can be cited as a check mechanism.

[0016] (2) Furthermore, in the energy storage device described in (1), it is preferable to have a flammable non-aqueous electrolyte contained in the housing and immersed in the electrode body.

[0017] (3) In addition, in the energy storage device described in (1), it is preferable that the electrode body has an electrode plate, and the electrode plate has an active material layer containing carbon-based active material particles.

[0018] (4) Furthermore, in the energy storage device described in (1), the safety valve may be disposed on the side wall of the housing constituting the housing, and the check mechanism may be airtightly installed from the outside on the valve surrounding the safety valve in the side wall of the housing, and airtightly covering the safety valve from the outside of the housing.

[0019] (5) In the energy storage device described in (1) above, the safety valve part may be provided on the side wall of the housing that constitutes the housing, and the check mechanism may be airtightly installed from the inside of the side wall of the housing around the valve part surrounding the safety valve part, and airtightly cover the safety valve part from the inside of the housing.

[0020] (6) In the energy storage device described in (1) above, the check mechanism may have a main body integrally formed with the housing sidewall constituting the housing, and the safety valve part may be integrally provided with the check mechanism.

[0021] (7) In the energy storage device described in (1) above, the composite valve part can be an independent composite valve structure, and the composite valve structure is installed on the side wall of the housing that constitutes the housing. Attached Figure Description

[0022] Figure 1 This is an enlarged partial cross-sectional view showing the vicinity of the safety valve and check mechanism constituting the composite valve section in the battery according to Embodiment 1.

[0023] Figure 2 This is an explanatory diagram illustrating the gas release through the safety valve and check mechanism, as described in Embodiment 1.

[0024] Figure 3 This is an explanatory diagram illustrating the state in which the check valve mechanism is closed after gas release, as described in Embodiment 1.

[0025] Figure 4 This is an enlarged partial cross-sectional view showing the vicinity of the safety valve and check mechanism constituting the composite valve section in the battery according to Embodiment 2.

[0026] Figure 5 This is an explanatory diagram illustrating the gas release through the safety valve and check mechanism, as described in Embodiment 2.

[0027] Figure 6 This is an explanatory diagram illustrating the state in which the check valve mechanism is closed after gas release, as described in Embodiment 2.

[0028] Figure 7 This is an enlarged partial cross-sectional view showing the vicinity of the safety valve and check mechanism constituting the composite valve section in the battery according to Embodiment 3.

[0029] Figure 8 This is an enlarged partial cross-sectional view showing the vicinity of the safety valve and check mechanism constituting the composite valve section in the battery according to Embodiment 4.

[0030] Figure 9 This is an enlarged partial cross-sectional view showing the vicinity of the safety valve and check mechanism constituting the composite valve structure in the battery according to Embodiment 5.

[0031] Figure 10 This is an enlarged sectional view of the vicinity of the safety valve and check mechanism, which constitute the composite valve structure in the battery involved in deformation mode 1. Detailed Implementation

[0032] (Implementation Method 1)

[0033] The following is for reference Figures 1 to 3 This describes a battery 1 (an example of an energy storage device) as a lithium-ion secondary battery according to an embodiment of the present invention. The battery 1 is a square and sealed lithium-ion secondary battery, which is installed in vehicles such as hybrid electric vehicles, plug-in hybrid electric vehicles, and electric vehicles, or in various devices.

[0034] The battery 1 of this embodiment comprises a casing 4, electrode bodies 2 housed inside the casing 4, positive and negative terminals (not shown) fixed to the casing 4, and electrolyte 3 housed within the casing 4. The casing 4 is made of metal (aluminum in this embodiment) and is a rectangular box shape. The electrode bodies 2 are covered inside the casing 4 by a bag-shaped insulating film (not shown). Furthermore, a portion of the electrolyte 3 housed within the casing 4 is immersed in the electrode bodies 2, while another portion accumulates at the bottom (not shown) of the casing 4.

[0035] The electrode 2 housed within the casing 4 consists of a rectangular plate-shaped positive electrode 2P and a rectangular plate-shaped negative electrode 2N separated by a rectangular plate-shaped separator 2S. Figure 1The electrodes are stacked in a direction orthogonal to the paper surface. The positive electrode plate 2P in the electrode body 2 has a positive electrode active material layer 2PA on both surfaces, consisting of positive electrode active material particles, conductive particles, and a binder. In this embodiment, lithium transition metal composite oxide particles are used as the positive electrode active material particles; specifically, lithium nickel cobalt manganese composite oxide particles are used, for example. Acetylene black (AB) is used as the conductive particles, for example. Polyvinylidene fluoride (PVDF) is used as the binder, for example. On the other hand, the negative electrode plate 2N has a negative electrode active material layer 2NA on both surfaces, consisting of negative electrode active material particles and a binder. In this embodiment, graphite particles 2NAC are used as the negative electrode active material particles. These graphite particles 2NAC are an example of carbon-based active material particles. In addition to the graphite particles mentioned above, other carbon-based active materials such as acetylene black and carbon nanotubes can also be used as carbon-based active material particles.

[0036] Electrolyte 3 is a flammable non-aqueous electrolyte containing an organic solvent and a fluorinated lithium salt as a supporting salt. In this embodiment, an organic solvent mixed with ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate is used as the organic solvent. LiPF6 is used as the fluorinated lithium salt. Examples of non-aqueous electrolytes include those prepared by dissolving the electrolyte salt in a flammable organic solvent as described above. Examples of flammable organic solvents used for non-aqueous electrolytes include cyclic carbonates such as propylene carbonate and ethylene carbonate, and chain carbonates such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0037] Furthermore, the battery 1 has a composite valve section 7 on one of the six sidewalls of the rectangular housing 4. Specifically, the cover 4S, which closes the opening of the bottomed rectangular cylindrical housing body (not shown), has a composite valve section 7 consisting of a non-resetting safety valve section 5 and a check valve section 6, which is an example of a check mechanism. Additionally, there is an internal housing space SP between the cover 4S and the housed electrode body 2. The pressure of the gas GS present in this internal housing space SP is set as the internal housing pressure PIC.

[0038] In this embodiment 1, the safety valve part 5 of the composite valve part 7 is provided on the cover body 4S. More specifically, the cover body 4S is obtained by stamping, and the safety valve part 5 is integrally formed with the cover body 4S. On the other hand, the check valve part 6, unlike the safety valve part 5, is a reset type valve part capable of repeated opening and closing. This check valve part 6 is located from the outside (in... Figure 1The valve periphery portion 4SV, which surrounds the safety valve portion 5, is airtightly installed in the cover body 4S from the outside of the cover body 4S, and airtightly covers the safety valve portion 5. In this embodiment 1, the foot portion 6Mf of the check valve portion 6 (described later) is airtightly welded to the valve periphery portion 4SV of the cover body 4S over its entire circumference by a weld portion 6W generated by laser welding. In this way, the check valve portion 6 is arranged in series with respect to the safety valve portion 5. That is, as described later, the gas discharge path is set such that the gas GS inside the housing 4 is released to the outside through the check valve portion 6 after the safety valve portion 5 is opened.

[0039] In this embodiment 1, the safety valve section 5 extends inward (inside) Figure 1 The valve body 5S consists of a circular recessed valve recess 5H (located on the lower side) and a thin plate-shaped valve body 5S disposed within the valve recess 5H. A slot 5N with a V-shaped cross-section is formed in the valve body 5S in a predetermined shape (e.g., a shape where a circle and an X overlap). The first opening pressure of the valve body 5S is the cracking pressure POs. That is, the valve body 5S cracks at the slot 5N when the pressure difference between the internal pressure Pic and atmospheric pressure exceeds the cracking pressure POs, which is the first opening pressure. Figure 2 As shown, the valve is opened by forming an outwardly warped slit 5B, releasing the gas GS in the housing space SP to the outside. Furthermore, this safety valve 5 is a type of non-resettable or destructive safety valve, meaning that once opened, it cannot be closed. Therefore, as... Figure 3 As shown, even if the pressure difference between the internal pressure PIC and atmospheric pressure is lower than the cracking pressure POs after the valve is opened, the cracked part 5B will not return to its original state, and the internal and external connections will remain unchanged through the safety valve part 5.

[0040] On the other hand, the check valve part 6 includes: a generally cylindrical valve body member 6M made of metal (aluminum in this embodiment 1); an annular valve orifice plate 6H made of stainless steel plate, which has a valve orifice BH in the center; a valve body plate 6B also made of stainless steel plate, which has a valve body part 6Bv in the center portion that blocks the valve orifice BH, and a gas passage hole PH extending in the thickness direction around the valve body part 6Bv; and a helical spring 6S made of spring steel. The valve body member 6M is composed of: a cylindrical foot 6Mf, which has an internal thread 6Ms on its inner side; a stepped cylindrical body part 6Md, which extends from the foot 6Mf outwards (in... Figure 1The valve body 6M extends from the upper side (center); and a top 6Mt, which is located outside the cylindrical portion 6Md, blocking the cylindrical portion 6Md from the outside, and has a top release hole RH as a through hole in the central part. In addition, the valve orifice plate 6H has an external thread 6Hs formed on its outer periphery. In the check valve portion 6, the helical spring 6S and the valve body plate 6B are sequentially inserted into the cylindrical portion space DS in the cylindrical portion 6Md of the valve body member 6M, and the valve orifice plate 6H with the external thread 6Hs on its outer periphery is screwed into the valve closing space BS in the foot 6Mf by the internal thread 6Ms of the foot 6Mf, and the valve body plate 6H with the external thread 6Hs on its outer periphery is screwed into the valve closing space BS in the foot 6Mf by the internal thread 6Ms of the foot 6Mf, and the valve body plate 6B then... Figure 1 The coil spring 6S is compressed in the vertical direction. Thus, through the elastic force of the coil spring 6S, the valve body plate 6B is tilted towards the valve orifice plate 6H (in... Figure 1 Force is applied from the lower side (center). As a result, the valve body portion 6Bv of the valve body plate 6B presses against the valve orifice plate 6H to block the valve orifice BH.

[0041] However, in the check valve section 6, relative to the air pressure (atmospheric pressure) in the cylinder space DS within the cylinder section 6Md (which is an open space), the air pressure in the valve closed space BS and valve orifice BH within the foot section 6Mf increases. When the differential pressure exceeds the opening pressure POr, which serves as the second opening pressure, such as... Figure 2 As shown, the valve body plate 6B moves upward, thereby releasing the valve body portion 6Bv from the valve orifice BH. Consequently, gas GS is discharged from the valve closed space BS through the valve orifice BH, the gap between the valve orifice plate 6H and the valve body plate 6B, the gas through hole PH, the cylinder space DS, and the top release hole RH to the outside.

[0042] Subsequently, when gas GS is released and the pressure difference between the valve closed space BS and valve orifice BH and the atmospheric pressure of the external gas AR is lower than the valve opening pressure POr, the valve body plate 6B moves downward and abuts against the valve orifice plate 6H by the force of the helical spring 6S, thereby closing the valve orifice BH again through the valve body part 6Bv. Thus, the check valve part 6 is a resettable valve part capable of repeated opening and closing. Furthermore, since the check valve part 6 maintains a closed valve when the pressure in the valve closed space BS and valve orifice BH is lower than the atmospheric pressure of the external gas AR, it also functions as a check valve to prevent the external gas AR from flowing back into the valve closed space BS from the top release hole RH. Moreover, in the unbroken state of the safety valve part 5, the pressure in the valve closed space BS and valve orifice BH is approximately the atmospheric pressure at the time of battery 1 manufacturing.

[0043] Furthermore, in the battery 1 of this embodiment 1, the opening pressure POr of the check valve section 6 is set to be lower than the burst pressure POs of the safety valve section 5 (POs > POr). Therefore, in the battery 1, if the internal pressure PIC of the casing rapidly increases due to reasons such as internal short circuit or abnormal heating, and the internal pressure PIC (the pressure difference between the internal pressure PIC and atmospheric pressure) exceeds the burst pressure POs, the safety valve section 5 opens. Then, the check valve section 6 opens (see reference). Figure 2 Therefore, the gas GS inside the housing 4 is released to the outside through the opening SO of the safety valve section 5 and the check valve section 6, which can safely reduce the internal pressure PIc of the housing.

[0044] Furthermore, when the release of gas GS is terminated and the differential pressure between the internal pressure PIC and atmospheric pressure is lower than the opening pressure POr of the check valve section 6, such as Figure 3 As shown, the opening SO remains open, meaning the safety valve 5 remains open while the check valve 6 remains closed. This prevents external gas AR from flowing back into the housing 4 from the outside. It also prevents the housing 4 from remaining in a state of constant communication between the inside and outside. Furthermore, in this embodiment 1, a valve closing space BS is provided within the foot 6Mf of the check valve 6, and a sufficiently high gap is provided between the valve body 5S and the valve orifice plate 6H. Therefore, it also prevents the opening 5B caused by the valve opening from hitting the valve orifice plate 6H, thus preventing insufficient opening of the valve body 5S.

[0045] Furthermore, as described above, in this battery 1, a flammable electrolyte 3 is contained within the casing 4. Additionally, the electrode body 2 has a negative electrode plate 2N, which has an active material layer containing carbon-based active material particles such as graphite particles. However, thanks to the aforementioned check valve mechanism, the backflow of external gas AR can be appropriately prevented. Therefore, it is possible to suppress the contact between the electrolyte 3 and the carbon-based active material particles within the casing 4 and the backflowing external gas AR, or to maintain their contact with the external gas AR.

[0046] Furthermore, in this battery 1, the safety valve part 5 is provided in the cover 4S, while the check valve part 6 is provided on the outside of the cover 4S. Therefore, the arrangement of the electrode body 2, terminal members (not shown), etc., housed in the housing 4 is minimally affected. In addition, since the check valve part 6 is not provided inside the housing 4, there are fewer restrictions on the material used for the check valve part 6, etc., and it has the advantage of high structural freedom for the check valve part 6. Furthermore, in this embodiment 1, as the safety valve part 5, a safety valve part 5 integrally formed with the cover 4S is provided by forming a part of the cover 4S by stamping or the like. However, it is also possible to airtightly fix a separately formed safety valve member by blocking the through hole provided in the cover 4S.

[0047] Furthermore, in the composite valve section 7 of the battery 1, a safety valve section 5 is used, which has a thin plate-shaped valve body section 5S with a groove 5N provided in the valve recess 5H. Therefore, when the safety valve section 5 is not open, high airtightness can be maintained at the safety valve section 5. In addition, it is easy to keep the opening pressure POs of the safety valve section 5 constant. In addition, the check valve section 6 is set to an opening pressure POr that is lower than the opening pressure POs of the safety valve section 5. Therefore, even if the opening pressure POr increases due to adhesion or contamination between the valve body section 6Bv and the valve orifice plate 6H, the increased opening pressure POr of the check valve section 6 does not exceed the opening pressure POs of the safety valve section 5, and the safety valve section 5 and the check valve section 6 can open normally. In this way, the tolerance for the variation of the opening pressure POr of the check valve section 6 is also high.

[0048] (Implementation Method 2)

[0049] Below, refer to Figures 4 to 6 The battery 11 according to the second embodiment will be described. Furthermore, the battery 11 of this embodiment 2, except for the composite valve section 17, is the same as the battery 1 of embodiment 1, so the description is omitted or simplified. The composite valve section 17 is composed of a safety valve section 5 and a check valve section 16, but the safety valve section 5 is the same as in embodiment 1. Therefore, the description will focus on the check valve section 16 in the composite valve section 17. This check valve section 16 is arranged in series with respect to the safety valve section 5. That is, in this embodiment 2, as described later, the gas discharge path is also set such that the gas GS inside the housing 14 is released to the outside through the check valve section 16 after the safety valve section 5 is opened.

[0050] The check valve section 16 in the composite valve section 17 is composed of a valve body component 16M and a valve fixing component 16R that fixes the valve body component 16M to the cover body 14S (described later). The valve fixing component 16R can be made of metal or resin, but in this embodiment, it is made of thermoplastic resin, specifically PPS, and is fixed to the outer surface 14Sa of the cover body 14S together with the valve body component 16M by injection molding.

[0051] On the other hand, the valve body component 16M of the check valve section 16 is formed by stamping a spring steel plate, and is composed of a fixed portion 16Mf fixed to the valve fixing component 16R, a leaf spring portion 16Ms extending from the fixed portion 16Mf, and a dome valve portion 16Mv provided at the front end of the leaf spring portion 16Ms and covering the safety valve section 5. Furthermore, the dome valve portion 16Mv includes an outward (in...) Figure 4The valve consists of a hemispherical dome 16Mvd (top side) and an annular abutment 16Mvs located around the periphery of the dome 16Mvd. The dome valve portion 16Mv is subjected to force through the elastic deformation of the leaf spring portion 16Ms, causing the annular abutment 16Mvs to be airtightly pressed against the valve periphery 14SV surrounding the safety valve portion 5 within the cover body 14S. Therefore, when the pressure difference between the valve closure space BS between the safety valve portion 5 and the dome valve portion 16Mv exceeds the opening pressure POr of the check valve portion 16, as... Figure 5 As shown, the dome valve section 16Mv is lifted, the annular abutment section 16Mvs moves away from the valve periphery section 14SV, and the gas GS in the valve closed space BS is released to the outside.

[0052] Subsequently, when gas GS is released and the pressure difference between the valve-closed space BS and atmospheric pressure is lower than the valve opening pressure POr, the dome valve part 16Mv moves downward by the force applied by the leaf spring part 16Ms, and the annular abutment part 16Mvs abuts against the valve periphery part 14SV, thereby closing the valve-closed space BS again. This check valve part 16 is also a reset type valve part capable of repeated opening and closing. In addition, the check valve part 16 maintains the closed valve when the pressure in the valve-closed space BS is lower than the pressure of the external gas AR, thus also serving as a check valve to prevent the external gas AR from flowing back into the valve-closed space BS from the outside.

[0053] Furthermore, in this embodiment 2, the opening pressure POr of the check valve section 16 is also set to be smaller than the burst pressure POs of the safety valve section 5 (POr < POs). Therefore, in the battery 11, if the internal pressure PIC inside the housing 14 rapidly increases due to reasons such as internal short circuit or abnormal heating, and the internal pressure PIC (the pressure difference between the internal pressure PIC and atmospheric pressure) exceeds the burst pressure POs, the safety valve section 5 opens. Then, the check valve section 16 opens (see reference). Figure 5 Therefore, the gas GS inside the housing 4 is released to the outside through the safety valve section 5 and the check valve section 16, which can safely reduce the internal pressure PIC of the housing.

[0054] Furthermore, when the release of gas GS is terminated and the differential pressure between the internal pressure PIC and atmospheric pressure is lower than the opening pressure POr of the check valve section 16, such as Figure 6As shown, the safety valve section 5 remains open, but the dome valve section 16Mv of the check valve section 16 is pressed against the valve periphery section 14SV to close the valve. This prevents external gas AR from flowing back into the housing 14 from the outside. Furthermore, it prevents the housing 14 from remaining in a state of constant communication between the inside and outside. In this embodiment 2, a valve closing space BS is also provided within the dome valve section 16Mv of the check valve section 16, and a sufficiently high gap is provided between the valve body section 5S and the dome 16Mvd. Therefore, it prevents the valve body section 5S from being insufficiently cracked or the dome valve section 16Mv from failing to close due to the cracked portion 5B caused by valve opening hitting the dome 16Mvd.

[0055] Furthermore, the check valve section 16 is set to have an opening pressure POr that is lower than the burst pressure POs of the safety valve section 5. Therefore, even if adhesion or contamination occurs between the annular contact portion 16Mvs of the check valve section 16 and the valve periphery portion 14SV of the cover body 14S, causing the opening pressure POr to rise, the safety valve section 5 and the check valve section 16 can open normally as long as the increased opening pressure POr of the check valve section 16 does not exceed the burst pressure POs of the safety valve section 5. In this way, the tolerance for fluctuations in the opening pressure POr of the check valve section 16 is also high.

[0056] (Implementation Method 3)

[0057] Below, refer to Figure 7 The battery 21 according to the third embodiment will be described. Furthermore, the battery 21 of this embodiment 3, except for the composite valve section 27, is the same as the battery 1 of embodiment 1, therefore its description is omitted or simplified. Additionally, the composite valve section 27 is composed of a safety valve section 5 and a check valve section 26, but the safety valve section 5 is the same as in embodiment 1. Therefore, the description will focus on the check valve section 26 within the composite valve section 27.

[0058] In embodiment 1, the check valve section 6 of the composite valve section 7 is disposed on the outside of the cover 4S and the safety valve section 5 (in Figure 1 (The middle is the upper side). In contrast, in the composite valve section 27 of this embodiment, the difference is that the check valve section 26 is provided inside the cover 24S and the safety valve section 5 (in Figure 7 (The middle is the lower side). That is, the check valve part 26 is airtightly installed from the inside into the valve periphery part 24SV surrounding the safety valve part 5 in the cover body 24S, and airtightly covers the safety valve part 5 from the inside of the cover body 24S. In this embodiment 3, the top 26Mt of the check valve part 26 is airtightly laser-welded to the valve periphery part 24SV of the cover body 24S by the welding part 26W. In this way, the check valve part 26 is arranged in series with respect to the safety valve part 5. That is, the gas discharge path is set so that the gas GS in the housing 24 is released to the outside through the open check valve part 26 and then through the safety valve part 5.

[0059] The check valve section 26 has a structure substantially the same as that of the check valve section 6 in Embodiment 1, and therefore will be described briefly. In addition to the generally cylindrical valve body member 26M, the check valve section 26 also includes the same valve orifice plate 6H, valve body plate 6B, and helical spring 6S as in Embodiment 1. The valve body member 26M consists of a foot portion 26Mf with an internal thread portion 26Ms, a cylindrical portion 26Md, and a portion extending from the outside (in... Figure 7 The top 26Mt (located on the upper side) is formed by blocking the cylindrical portion 26Md and having a top release hole RH. In the check valve portion 26, a helical spring 6S and a valve body plate 6B are sequentially inserted into the cylindrical portion 26Md, and the valve orifice plate 6H is screwed into the foot portion 26Mf using the internal thread portion 26Ms and the external thread portion 6Hs, thereby compressing the helical spring 6S in the vertical direction via the valve body plate 6B. In this way, the elastic force of the helical spring 6S applies force to the valve body plate 6B toward the valve orifice plate 6H, thereby blocking the valve orifice BH by the valve body portion 6Bv of the valve body plate 6B. However, unlike the check valve portion 6 of Embodiment 1, in the check valve portion 26, a valve closing space BS is not provided inside the foot portion 26Mf.

[0060] In this check valve section 26, relative to the internal pressure Pd of the cylindrical section space DS (which serves as a closed space) and the top release hole RH, the internal pressure PIc of the housing space SP and the valve hole BH increases. When the pressure difference between the internal pressure PIc of the housing and the internal pressure Pd of the cylindrical section exceeds the valve opening pressure POr, the valve body plate 6B moves upward, thereby releasing the closure of the valve body section 6Bv to the valve hole BH. Therefore, the gas GS in the housing space SP passes through the valve hole BH, the gap between the valve hole plate 6H and the valve body plate 6B, the gas passage hole PH, and the cylindrical section space DS, reaching the top release hole RH located inside the valve body section 5S. The internal pressure Pd of the cylindrical section space DS and the top release hole RH rises towards the internal pressure PIc of the housing. Furthermore, when the internal pressure Pd of the cylinder reaches a pressure that is lower than the internal pressure Pic of the housing by an amount corresponding to the valve opening pressure Por, the valve body plate 6B moves downward and comes into contact with the valve body plate 6B through the force of the helical spring 6S, thereby closing the valve orifice BH again through the valve body section 6Bv. Thus, the check valve section 26 of this embodiment 3 is also a resettable valve section capable of repeated opening and closing. Moreover, when the internal pressure Pd of the cylinder is lower than the breaking pressure Pos of the safety valve section 5, the safety valve section 5 does not open, and the internal pressure Pd of the cylinder remains at a pressure that is approximately lower than the internal pressure Pic of the housing space SP by an amount corresponding to the valve opening pressure Por.

[0061] Furthermore, in the battery 21 of this embodiment 3, the opening pressure POr of the check valve section 26 is also set to be lower than the breaking pressure POs of the safety valve section 5 (POs > POr). Therefore, when the internal pressure PIC of the housing rapidly increases due to reasons such as internal short circuit or abnormal heating, firstly, the differential pressure with the internal pressure Pd of the cylinder exceeds the opening pressure POr, and the check valve section 26 opens, allowing gas GS to flow into the cylinder space DS and the top release hole RH. As a result, the internal pressure Pd of the cylinder rises towards the internal pressure PIC of the housing. Here, when the internal pressure Pd of the cylinder exceeds the breaking pressure POs, the safety valve section 5 opens (breaks) after the check valve section 26. As a result, the gas GS in the internal space SP of the housing 24 is released to the outside through the check valve section 26 of the equalization valve and the safety valve section 5, and the internal pressure PIC of the housing can be safely reduced.

[0062] Furthermore, when the release of gas GS ends and the pressure difference between the internal pressure PIC and atmospheric pressure is lower than the opening pressure POr of the check valve section 26, the safety valve section 5 remains open, but the check valve section 26 is closed. This prevents external gas AR from flowing back into the housing 24 from the outside. In other words, the check valve section 26 functions as a check valve. Additionally, it prevents the housing 24 from remaining in a state of constant communication between the inside and outside.

[0063] In the battery 21 of this embodiment 3, the safety valve 5 is provided on the cover 24S, while the check valve 26 is provided on the inner side. Therefore, the check valve 26 is not easily affected by external contamination or other damage. In addition, since the check valve 26 is not provided outside the housing 4, it has the advantage of high flexibility in the arrangement of the battery 21.

[0064] Furthermore, in the composite valve section 27 of the battery 21, a safety valve section 5 is also used, which has a thin plate-shaped valve body section 5S with a groove 5N provided in the valve recess 5H. Therefore, high airtightness can be maintained when the safety valve section 5 is not open. In addition, it is easy to keep the cracking pressure POs constant.

[0065] (Implementation Method 4)

[0066] Below, refer to Figure 8 The battery 31 according to the fourth embodiment will be described. Furthermore, the parts of the battery 31 in this embodiment 4, except for the composite valve section 37, are the same as the batteries 1 and 21 in embodiments 1 and 3, and will be omitted or simplified in description. Hereinafter, the description will focus on the composite valve section 37.

[0067] In embodiments 1 and 3, the non-resettable safety valve 5 in the composite valve sections 7 and 27 is integrally formed with the cover bodies 4S and 24S. On the other hand, the check valve sections 6 and 26, which are separate from the cover bodies 4S and 24S, are airtightly connected to the valve periphery portions 4SV and 24SV of the cover bodies 4S and 24S. In contrast, the composite valve section 37 in this embodiment 4 differs in that the valve body portion 36M in the check valve section 36 is integrally formed with the cover body 34S, and the non-resettable safety valve member 35 is fixedly formed on the valve body portion 36M.

[0068] Furthermore, the check valve section 36 has a structure substantially the same as that of the check valve sections 6 and 26 in embodiments 1 and 3, and therefore will be described briefly. The check valve section 36, in addition to being integrally formed with the cover 34S by stamping or the like and extending outwards from the cover 34S (in... Figure 8 In addition to the generally cylindrical valve body 36M protruding from the upper side (center), it also includes the same valve orifice plate 6H, valve body plate 6B, and helical spring 6S as in embodiments 1 and 3. Furthermore, the valve body 36M consists of a foot 36Mf with an internally threaded portion 36Ms on its inner side, a cylindrical cylindrical body 36Md extending outward from the foot 36Mf, and a top 36Mt located further outward than the cylindrical body 36Md, blocking the cylindrical body 36Md from the outside and having a top release hole RH as a through hole in its central portion. In this check valve 36, the elastic force of the compressed helical spring 6S applies force to the valve body plate 6B towards the valve orifice plate 6H, thereby blocking the valve orifice BH through the valve body portion 6Bv of the valve body plate 6B. However, similar to the check valve 26 in embodiment 3, the check valve 36 does not have a valve closing space BS inside the foot 36Mf.

[0069] On the other hand, the non-resetting safety valve component 35, which is separate from the cover 34S, is hermetically fixed to the top 36Mt of the valve body 36M, which is integrally formed with the cover 34S. This safety valve component 35 is manufactured by stamping aluminum sheet. Similar to embodiments 1 and 3, a thin-plate-shaped valve body 35S with a groove 35N is integrally formed within a valve recess 35H located within a thick valve periphery portion 35P. In this embodiment 4, the safety valve component 35 is arranged such that the valve body 35S overlaps with the top release hole RH of the top 36Mt, and the valve periphery portion 35P is hermetically laser-welded to the top 36Mt around its entire circumference. Alternatively, an adhesive can be used to hermetically fix the valve periphery portion 35P of the safety valve component 35 to the top 36Mt around its entire circumference.

[0070] In this embodiment 4, the opening pressure POr of the check valve section 36 is also set to be lower than the burst pressure POs of the safety valve member 35 (POs > POr). Therefore, similar to embodiment 3, in the battery 31, if the internal pressure PIC of the housing rises rapidly, the check valve section 36 opens, and gas GS flows into the cylinder space DS and the top release hole RH. Furthermore, if the internal pressure Pd of the cylinder exceeds the burst pressure POs, the check valve section 36 and the safety valve member 35 then open (burst). Gas GS is released to the outside through the check valve section 36 and the safety valve member 35 arranged in series, which can safely reduce the internal pressure PIC of the housing. Then, when the pressure difference between the internal pressure PIC of the housing and atmospheric pressure is lower than the opening pressure POr, the check valve section 36 closes, thus preventing the backflow of external gas AR into the housing 34. In addition, it can also prevent the housing 34 from remaining in a state of constant communication between the inside and outside. In addition, the battery 31 in this embodiment 4 also has the same effect as the battery 21 in embodiment 3.

[0071] Furthermore, in this battery 31, the valve body 36M of the check valve section 36 is integrally formed with the cover 34S. Additionally, the safety valve component 35 is integrally provided with the check valve section 36. Therefore, an energy storage device having a check valve section 36 integrally formed with the cover 34S and a safety valve component 35 integrally formed with it can be provided with a simple structure.

[0072] Furthermore, in this embodiment 4, an example is shown where a separate safety valve component 35 is fixed to the top 36Mt. However, the separate safety valve component 35 may also be configured and fixed to the foot 36Mf of the check valve section 36 or the inside of the valve orifice plate 6H so that the valve body 35S overlaps with the valve orifice BH to block it. Alternatively, a valve body 35S with a groove 35N may be integrally formed in the top release hole RH of the top 36Mt of the check valve section 36, or a valve body 35S with a groove 35N may be integrally formed in the valve orifice BH of the valve orifice plate 6H, thus integrally providing a non-resetting type safety valve section to the components constituting the check valve section.

[0073] (Implementation Method 5, Variation 1)

[0074] Below, refer to Figure 9 The battery 41 according to the fifth embodiment will be described below. Furthermore, the parts of the battery 41 in this embodiment 5, except for the composite valve structure 47, are the same as the batteries 1, 21, and 31 in embodiments 1, 3, and 4, and will be omitted or simplified in description. Hereinafter, the description will focus on the composite valve structure 47.

[0075] In embodiments 1, 3, and 4, a portion of the composite valve parts 7, 27, and 37, namely the safety valve part 5 or the check valve part 36, is integrally provided with the cover body 4S, 24S, and 34S. In contrast, unlike embodiments 1, the check valve part 46 and the safety valve member 35 constituting the composite valve structure 47 in embodiment 5 are separate from the cover body 44S; the composite valve structure 47 is a structure independent of the housing 44. Furthermore, unlike embodiments 1, a gas flow hole 44h is provided in the cover body 44S, and the foot 46Mf of the check valve part 46 in the composite valve structure 47 is airtightly mounted from the outside to the surrounding portion 44Sr of the gas flow hole 44h via a welded portion 46W. Moreover, the valve hole BH of the check valve part 46 is configured such that the valve hole plate 6H overlaps with the gas flow hole 44h.

[0076] Furthermore, the safety valve component 35 in the composite valve structure 47 is the same as the safety valve component 35 in Embodiment 4, so its description is omitted. Additionally, the check valve section 46 has a structure substantially the same as the check valve sections 6, 26, and 36 in Embodiments 1, 3, and 4, so its description is brief. In addition to having a generally cylindrical valve body component 46M, the check valve section 46 also has a valve orifice plate 6H, a valve body plate 6B, and a helical spring 6S, similar to those in Embodiment 1. The valve body component 46M consists of a foot portion 46Mf with an internal thread portion 46Ms, a cylindrical portion 46Md, and a portion extending from the outside (in... Figure 9 The top 46Mt (located on the upper side) is formed by blocking the cylinder portion 46Md and having a top release hole RH. In the check valve portion 46, the valve body plate 6B is forced towards the valve orifice plate 6H by a compressed helical spring 6S, and the valve orifice BH is blocked by the valve body portion 6Bv. Similar to embodiment 4, a safety valve member 35 is airtightly fixed to the top 46Mt of this check valve portion 46.

[0077] In this embodiment 5, the opening pressure POr of the check valve section 46 is also set to be lower than the burst pressure POs of the safety valve member 35 (POs > POr). Therefore, in the battery 41, if the internal pressure PIC of the housing rises rapidly, the check valve section 46 opens, and gas GS flows into the cylinder space DS and the top release hole RH. Furthermore, if the internal pressure Pd of the cylinder exceeds the burst pressure POs, the check valve section 46 and the safety valve member 35 then open, thereby safely reducing the internal pressure PIC of the housing. In addition, if the pressure difference between the internal pressure PIC of the housing and atmospheric pressure is lower than the opening pressure POr, the check valve section 46 closes, thereby preventing the backflow of external gas AR into the housing 44. In addition, it can prevent the inside and outside of the housing 44 from remaining connected. In addition, the battery 41 of this embodiment 5 also has the same effect as the batteries 21 and 31 of embodiments 3 and 4.

[0078] Furthermore, in battery 41, the composite valve section, including safety valve component 35 and check valve section 46, constitutes a separate composite valve structure 47. The composite valve structure 47 is mounted on the cover 44S. Therefore, compared to the case where the valve body of the safety valve section or check valve section is integrally formed with the side wall of the housing, the composite valve structure 47 offers greater freedom in its shape and construction. Moreover, by mounting the composite valve structure 47 to the side wall of the housing, an energy storage device equipped with a safety valve section and a check mechanism can be formed.

[0079] Furthermore, the composite valve structure 47 can be disposed on the outer side of the cover 44S as in embodiment 5, but it can also be disposed on the inner side. Alternatively, the composite valve structure can be configured to penetrate the sidewall of the housing, with a portion located on the outer side of the housing and the remaining portion located on the inner side. For example, as... Figure 10 In the modified battery 51 shown, a circumferentially protruding annular flange 56Mdf is provided on the cylindrical portion 46Md of the check valve portion 46. Furthermore, this flange 56Mdf can be hermetically mounted around its entire circumference to the periphery 54Sr of the hole surrounding the member insertion hole 54h that passes through the cover 54S of the housing 54 via a welding portion 56W. In this case, the protrusion height of both the outer and inner sides of the composite valve structure 47 can be suppressed. Additionally, the composite valve structure can be configured such that the safety valve member 35 is positioned on the outer side relative to the check valve portion 46, as in embodiment 5; conversely, it can also be configured such that the safety valve member is positioned on the inner side.

[0080] The present invention has been described above based on embodiments 1 to 5 and variations 1. However, the present invention is not limited to the embodiments, etc. It goes without saying that it can be applied by appropriate modifications without departing from its spirit.

[0081] For example, in Embodiment 1, an example is shown where a composite valve portion 7 is provided on the cover 4S in one of the six side walls of the rectangular shell 4. However, composite valve portions may also be provided on other side walls of the shell. Alternatively, composite valve portions may be provided at multiple locations.

[0082] Explanation of reference numerals in the attached figures

[0083] 1, 11, 21, 31, 41, 51 Batteries (Electronic Storage Devices)

[0084] 2 Electrode body

[0085] 3. Electrolyte (non-aqueous electrolyte)

[0086] 4, 14, 24, 34, 44, 54 Casing

[0087] SP housing internal space

[0088] PIc internal pressure

[0089] 4S, 14S, 24S, 34S, 44S, 54S Cover (Shell Side Wall)

[0090] Surrounding parts of 4SV, 14SV, and 24SV valves

[0091] 5. Safety Valve Section

[0092] 35 Safety valve components (safety valve section)

[0093] POs (First Opening Pressure)

[0094] 35P valve surrounding area

[0095] 6, 16, 26, 36, 46 Check valve section (check valve mechanism)

[0096] POr Opening pressure (second opening pressure)

[0097] 6M, 16M, 26M, 46M valve body components

[0098] 36M Valve Body (Main Body)

[0099] 7, 17, 27 Composite valve section

[0100] 37, 47 Composite valve structure (composite valve section)

[0101] GS Gas

[0102] AR (External Gas)

Claims

1. An energy storage device, wherein, The energy storage device includes: A shell made of metal; as well as Electrode housing within the casing. The housing has a composite valve section, the composite valve section comprising: A non-reset type safety valve section, wherein the opening pressure of the safety valve section is a first opening pressure; and A check valve mechanism is configured in series with the safety valve section, and the valve opening pressure is a second valve opening pressure that is lower than the first valve opening pressure. The check valve mechanism closes the valve by reducing the internal pressure of the housing after the gas is released due to the opening of the safety valve section and the check valve mechanism, thereby preventing external gas from flowing into the housing from the outside of the housing.

2. The energy storage device according to claim 1, wherein, The energy storage device has a flammable non-aqueous electrolyte housed within the housing and immersed in the electrode body.

3. The energy storage device according to claim 1, wherein, The electrode body has an electrode plate, and the electrode plate has an active material layer containing carbon-based active material particles.

4. The energy storage device according to claim 1, wherein, The safety valve is disposed on the side wall of the housing that constitutes the housing. The check valve mechanism is airtightly installed from the outside into the valve periphery surrounding the safety valve portion in the side wall of the housing, and airtightly covers the safety valve portion from the outside of the housing.

5. The energy storage device according to claim 1, wherein, The safety valve is disposed on the side wall of the housing that constitutes the housing. The check valve mechanism is airtightly installed from the inside of the housing sidewall around the valve portion surrounding the safety valve portion, and airtightly covers the safety valve portion from the inside of the housing.

6. The energy storage device according to claim 1, wherein, The check valve mechanism has a main body integrally formed with the sidewall of the housing that constitutes the housing. The safety valve section is integrally formed with the check valve mechanism.

7. The energy storage device according to claim 1, wherein, The composite valve section constitutes an independent composite valve structure. The composite valve structure is mounted on the side wall of the housing that constitutes the housing.

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