Power storage device and method for detecting state of power storage device

Abstract

A power storage device is provided with: a power storage unit; a bottomed cylindrical case that accommodates the power storage unit and has an opening at one end; a sealing member for sealing the opening; and a collector plate (14), the collector plate (14) being provided with: a first region (14A) electrically connected to an external terminal of the sealing member or the housing; a second region (14B) joined to the power storage unit; one or a plurality of first conduction parts (15A) connecting the first region and the second region; and one or more second conduction parts (15B) connecting the first region and the second region, the resistance of the first conduction part (15A) being different from the resistance of the second conduction part (15B).

Description

Technical Field

[0001] The present disclosure relates to an electric storage device and a method for detecting a state of the electric storage device. Background Art

[0002] As the demand for in-vehicle applications and the like expands, power storage devices represented by secondary batteries are required to have further higher output and higher capacity.

[0003] As a current collecting structure for obtaining high output, a so-called end face current collecting structure has been studied in which an exposed portion of a negative electrode current collector or a positive electrode current collector is protruded from an end face of a wound electrode group and welded to a current collecting plate.

[0004] As an example of an electric storage device having an end-face current collecting structure, for example, Patent Document 1 describes an electric storage device, which comprises: an electric storage element having a first electrode and a second electrode, and having a first end portion from which the first electrode is led out; an electrolyte impregnated in the electric storage element; a terminal plate having an element connection portion electrically connected to the first electrode at the first end portion and an external terminal portion connected to the element connection portion; an outer casing having a cylindrical shape with an opening portion, which accommodates the electric storage element together with the electrolyte; and a sealing member having an insertion hole for inserting the external terminal portion, and sealing the opening portion of the outer casing together with the external terminal portion. The external terminal portion is a column or a cylinder having a tapered portion at the outer periphery of the front end, and the end edge of the side wall of the opening portion of the outer casing is located between the two ends of the tapered portion in the direction of the outer casing extending from the bottom surface to the opening portion.

[0005] Patent document 2 describes a cylindrical secondary battery, which is a cylindrical secondary battery in which a plate group formed by winding a positive electrode plate and a negative electrode plate with a separator is stored together with an electrolyte in a battery container composed of a sealing plate and a metal outer can, wherein at least one of the positive electrode plate and the negative electrode plate has a core material exposed portion at the end along its length direction, and the core material exposed portion of either the positive electrode plate or the negative electrode plate protrudes from at least one of the upper surface and the lower surface of the plate group, and a flat portion is formed by the front end of the protruding portion itself, and a collector plate is joined to the flat portion. The collector plate is composed of a fixed portion joined to the flat portion and a movable portion joined to the bottom of the outer can, and further, a part of the movable portion includes the outer peripheral surface of the collector plate.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application No. 2013-088724

[0009] Patent Document 2: Japanese Patent Application Publication No. 2004-139777 Summary of the invention

[0010] Problems to be solved by the invention

[0011] In a power storage device having an end-face current collection structure, when the internal pressure in the device rises, the sealing member and the housing are deformed by expansion due to the pressure, and the current collector plate is deformed along with the deformation of the sealing member and the housing. At this time, along with the deformation of the current collector plate, the joint between the power storage unit (element) and the current collector plate is sometimes peeled off, and the current collection performance is reduced.

[0012] The more the capacity and output of the power storage device are increased, the more gas is generated during abnormal heating, and the easier it is for the internal pressure to rise. By using the collector plate described in Patent Document 2, it is possible to suppress the peeling of the welded portion of the collector plate from external vibration and impact, but the effect is not sufficient for the purpose of suppressing the peeling of the welded portion due to deformation of the collector plate caused by the increase in internal pressure. In addition, in the collector plate described in Patent Document 2, by providing a movable part, the current path flowing in the collector plate becomes longer even in normal use, so the internal resistance increases.

[0013] Means for solving problems

[0014] One aspect of the present disclosure relates to an electric storage device, comprising: an electric storage unit; a bottomed cylindrical shell, which accommodates the electric storage unit and has an opening at one end; a sealing member, which seals the opening; and a collector plate, wherein the collector plate comprises: a first region, which is electrically connected to an external terminal, which is an external terminal possessed by the sealing member or the shell; a second region, which is joined to the electric storage unit; one or more first conductive portions, which connect the first region with the second region; and one or more second conductive portions, which connect the first region with the second region, wherein the resistance of the first conductive portion is different from the resistance of the second conductive portion.

[0015] Another aspect of the present disclosure relates to an electrical storage device, comprising: an electrical storage unit; a shell that accommodates the electrical storage unit and has a bottomed cylindrical shape with an opening at one end; a sealing member that seals the opening; and a collector plate, the collector plate comprising: a first region that is electrically connected to an external terminal, the external terminal being an external terminal possessed by the sealing member or the shell; a second region that is joined to the electrical storage unit; one or more first conductive portions that connect the first region to the second region; and one or more second conductive portions that connect the first region to the second region, wherein if the internal pressure in the shell exceeds a specified first pressure, at least a portion of the first conductive portion of the collector plate breaks, while the second conductive portion does not break.

[0016] Yet another aspect of the present disclosure relates to a method for detecting a state of an electric storage device. In the above electric storage device, the method detects the state of the electric storage device by detecting a change in an electrical characteristic of the electric storage device caused by a break in the first conductive portion.

[0017] Effects of the Invention

[0018] Even when the internal pressure of the power storage device increases, the separation of the connection between the power storage cell and the current collector plate due to deformation of the current collector plate can be suppressed. In addition, the state change of the power storage device due to the increase in the internal pressure can be detected in a simple method.

[0019] While the novel features of the present invention are described within the scope of the appended claims, the present invention both in structure and content, together with other objects and features of the present invention, will be better understood from the following detailed description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1A It is a plan view showing the appearance of a current collector plate according to an embodiment of the present disclosure.

[0021] Figure 1B It is a perspective view showing the appearance of a current collector plate according to an embodiment of the present disclosure.

[0022] Figure 2 It means in Figure 1A and Figure 1B The current collector plate shown is a perspective view of the appearance of the current collector plate when the internal pressure of the case exceeds the first pressure and the first conductive portion is broken.

[0023] Figure 3A It is a plan view showing another example of the current collector plate according to the embodiment of the present disclosure.

[0024] Figure 3B It is a perspective view showing another example of the current collector plate according to the embodiment of the present disclosure.

[0025] Figure 4 It means in Figure 3A and Figure 3B The current collector plate shown is a perspective view of the appearance of the current collector plate when the internal pressure of the case exceeds the first pressure and the first conductive portion is broken.

[0026] Figure 5 It is a longitudinal sectional view showing the structure of the power storage device according to the embodiment of the present disclosure. DETAILED DESCRIPTION

[0027] [Electricity storage equipment]

[0028] Hereinafter, examples are given to illustrate the implementation of the power storage device of the present disclosure, but the present disclosure is not limited to the examples described below. In the following description, specific numerical values, materials, etc. are sometimes exemplified, but other numerical values, materials, etc. may also be applied as long as the effects of the present disclosure can be obtained. In this specification, a description such as "numerical value A to numerical value B" includes numerical value A and numerical value B, and can be replaced by "above numerical value A and below numerical value B". In the following description, when the lower limit and upper limit of numerical values ​​related to specific physical properties, conditions, etc. are exemplified, as long as the lower limit does not become above the upper limit, any one of the exemplified lower limits and any one of the exemplified upper limits can be arbitrarily combined. When multiple materials are exemplified, one may be selected and used alone, or two or more may be used in combination.

[0029] In addition, the present disclosure includes a combination of matters recorded in two or more claims arbitrarily selected from the plurality of claims recorded in the attached claims. That is, matters recorded in two or more claims arbitrarily selected from the plurality of claims recorded in the attached claims can be combined as long as no technical contradiction occurs.

[0030] An electric storage device according to one embodiment of the present disclosure comprises: an electric storage unit; a bottomed cylindrical housing that accommodates the electric storage unit and has an opening at one end; a sealing member that seals the opening; and a collector plate. The collector plate comprises: a first region that is electrically connected to an external terminal of the sealing member or the housing; and a second region that is joined to the electric storage unit.

[0031] The collector plate also includes: one or more first conductive parts connecting the first region and the second region; and one or more second conductive parts connecting the first region and the second region. At least two conductive paths for current to flow between the electrical connection position with the external terminal of the first region and the connection position with the storage unit of the second region are independently formed through the first conductive part and the second conductive part. In the normal state of the storage device, the current flows in parallel through both the conductive path (first conductive path) through the first conductive part and the conductive path (second conductive path) through the second conductive part.

[0032] When the internal pressure of the power storage device increases due to abnormal discharge or the like, the central portion of the collector plate expands toward the external terminal side and is deformed away from the power storage unit. At this time, due to the deformation, the connection between the second region of the collector plate and the power storage unit may be peeled off. Such peeling of the connection may also occur at an internal pressure lower than the valve operating pressure of the power storage device.

[0033] In one embodiment of the power storage device disclosed herein, the power storage device is configured so that if the internal pressure in the shell exceeds a specified first pressure, at least a portion of the first conductive portion breaks. On the other hand, even if the internal pressure exceeds the first pressure, the second conductive portion will not break. That is, if the internal pressure exceeds the first pressure, the first conductive path between the first region and the second region via the first conductive portion is cut off, and the current flows to the second conductive path via the second conductive portion between the first region and the second region. By detecting the change in electrical characteristics caused by this (for example, the change in the internal resistance of the device), the state of the power storage device can be detected. In addition, the separation of the joint with the power storage unit in the second region due to the deformation of the collector plate can be suppressed.

[0034] When the internal pressure of the case exceeds the first pressure, the second conductive portion is deformed so that the first region protrudes toward the external terminal side (the side away from the storage element) in the axial direction of the case as the first conductive portion breaks (see Figure 2 , Figure 4 ). Thus, deformation of the second region is suppressed, and separation of the connection with the power storage cell due to deformation of the collector plate is suppressed.

[0035] The resistance of the first conductive portion may be different from the resistance of the second conductive portion. In order to reduce the internal resistance of the device in a normal state where the internal pressure of the housing is equal to or lower than the first pressure, the resistance of the first conductive portion is preferably lower than the resistance of the second conductive portion.

[0036] In order to make the resistance of the first conductive part lower than that of the second conductive part, the length of the first conductive part may be shorter than that of the second conductive part. On the other hand, in order to make the first conductive part easier to break than the second conductive part as the internal pressure of the housing increases, the minimum width of the first conductive part may be narrower than the minimum width of the second conductive part.

[0037] Here, the length of the first conductive portion and the second conductive portion refers to the shortest length or average length along the first conductive path and the second conductive path, respectively. In the case of forming a curved path of the first conductive path and / or the second conductive path, the length of the first conductive portion and the second conductive portion is the shortest total length along the curved path, or the average total length, respectively. The width of the first conductive portion and the second conductive portion refers to the length in a direction perpendicular to the direction along the first conductive path and the direction along the second conductive path, respectively.

[0038] As an example of the structure of the collector plate having the first conductive portion and the second conductive portion, a plurality of slits (openings or through holes) may be intermittently formed along the contour of the first region. The slits separate the first region and the second region. For example, the region sandwiched between the ends in the length direction of the plurality of slits connects the first region and the second region with the minimum width, thereby forming the first conductive portion. The slits are not formed in a portion of the contour of the first region, and the portion of the contour of the first region where the slits are not formed (the portion that does not constitute the minimum width) is continuous with the second conductive portion.

[0039] The first region includes, for example, the central portion of the collector plate. In this case, the second region is disposed at the outer peripheral portion that is closer to the outside than the central portion. The first conductive portion and the second conductive portion connect the first region of the central portion to the second region disposed at the outer periphery at different positions in the circumferential direction. The first conductive portion can connect the central portion to the outer periphery in a manner that forms a conductive path that connects the central portion to the outer periphery at a short distance. At this time, the second conductive portion independently forms other conductive paths that flow in a circuitous manner between the first region and the second region from the conductive path that passes through the first conductive portion.

[0040] The storage unit is, for example, a columnar winding body formed by winding a positive electrode and a negative electrode with a separator therebetween. The winding body (storage unit) can be housed in the housing in such a manner that one end face of the winding body faces the bottom of the housing, and the other end face faces the sealing member on the opening side of the housing. The opening of the housing is closed in the state of housing the winding body, and maintained airtight. In addition, the sealing method of the opening of the sealing housing is not particularly limited, and a known method can be used.

[0041] Alternatively, the collector plate having the first conductive portion and the second conductive portion is joined to one end face of the winding body, joined to the electrode exposed at one end face in the second region, and electrically connected to the terminal portion of the sealing member in the first region. Alternatively, the collector plate having the first conductive portion and the second conductive portion is joined to the other end face of the winding body, joined to the electrode exposed at the other end face in the second region, and electrically connected to the bottom of the shell in the first region. The power storage device may include a pair of collector plates consisting of a collector plate joined to one end face of the winding body and a collector plate joined to the other end face of the winding body. Alternatively, one of the pair of collector plates is a collector plate having the first conductive portion and the second conductive portion, and both of the pair of collector plates are collector plates having the first conductive portion and the second conductive portion. In the following, the collector plate having the above-mentioned first conductive portion and the second conductive portion, which is joined to the end surface of one side of the winding body and electrically connected to the terminal portion of the sealing member is sometimes referred to as the first collector plate, and the collector plate having the above-mentioned first conductive portion and the second conductive portion, which is joined to the end surface of the other side of the winding body and electrically connected to the bottom of the shell is sometimes referred to as the second collector plate.

[0042] The collector plate has two main surfaces. In this case, the first main surface of the collector plate is opposite to the bottom of the sealing member or the shell, and the second main surface of the collector plate is opposite to the end surface of the winding body. In order to easily form a connection with the storage unit, the second area of ​​the collector plate can also protrude toward the second main surface. The first area of ​​the collector plate can also protrude toward the first main surface.

[0043] Alternatively, in the first current collector plate, the first region is electrically connected to the terminal portion of the sealing member, and the second region is joined to the first electrode of the storage cell. In this case, the first region may be joined to the terminal portion by welding. The second region may be joined to the first electrode of the storage cell by welding.

[0044] In the second current collector plate, the first region may be electrically connected to the case, and the second region may be joined to the second electrode of the storage cell. The second region may be joined to the second electrode of the storage cell by welding.

[0045] One of the first electrode and the second electrode is a positive electrode, and the other is a negative electrode. The collector plate can be electrically connected to the positive electrode or the negative electrode according to the structure of the power storage device. That is, the collector plate can be a positive collector plate or a negative collector plate. It is also possible that the first collector plate electrically connected to the terminal portion of the sealing member is electrically connected to the positive electrode, and the second collector plate electrically connected to the shell is electrically connected to the negative electrode. It is also possible that the first collector plate electrically connected to the terminal portion of the sealing member is electrically connected to the negative electrode, and the second collector plate electrically connected to the shell is electrically connected to the positive electrode.

[0046] When the power storage device includes a first collector plate and a second collector plate, the first collector plate and the second collector plate may have the same structure or different structures. Alternatively, the shape of at least one of the first conductive portion and the second conductive portion may be different in the first collector plate and the second collector plate. The threshold value of the internal pressure at which the first conductive portion breaks (first pressure), the resistance value when the first conductive portion breaks, the resonance frequency and other characteristics may be different in the first collector plate and the second collector plate.

[0047] When the pressure inside the shell of the collector plate exceeds the first pressure, as described above, the second conductive portion deforms as the first conductive portion breaks, and the first region protrudes toward the external terminal side (the side away from the storage element) in the axial direction of the shell. At this time, in the deformed collector plate, the second conductive portion acts as a spring with respect to the axial vibration, and the storage element is prone to axial vibration in the shell with respect to the external force, and there is a case where the vibration resistance of the storage device is reduced. In order to maintain the vibration resistance of the storage device at a high level, the resonant frequency of the storage device is preferably maintained at 500 Hz or more, for example.

[0048] The spring constant of the first collector plate with respect to the axial vibration when the first conductive part is broken is k1. The spring constant of the second collector plate with respect to the axial vibration when the first conductive part is broken is k2. The mass of the storage element is M, and the resonance frequency of the storage device is f n It is given by the following formula.

[0049] f n =((k1+k2) / M) 1 / 2 / 2π

[0050] For example, when the second conductive portion is designed as a flat spring with both ends fixed, the spring constant k (k1 or k2) is given by the following formula.

[0051] k=192EI / L 3

[0052] E: Young's modulus

[0053] I: Second moment of area (=bh 3 / 12)

[0054] L: Length of the second conductive portion

[0055] b: Width of the second conductive portion

[0056] h: thickness of the second conductive portion

[0057] In the above formula, the spring constants k1 and k2 can be calculated by numerical simulation taking into account the material (elastic constant) and shape of the collector plate. n It can also be calculated by numerical simulation. As numerical simulation software, for example, ANSYS is used.

[0058] In an energy storage device, the first collector plate opposed to the sealing member is more susceptible to deformation caused by expansion when the internal pressure of the shell increases than the second collector plate opposed to the bottom of the shell, and the connection with the energy storage unit is easily peeled off due to the deformation of the collector plate. Therefore, in the first collector plate, it is more necessary to suppress the peeling of the connection with the energy storage unit than the second collector plate. Therefore, it is sufficient to design the shape of the second conductive portion of the first collector plate in such a way that when the first conductive portion breaks, the first region of the first collector plate is easily deformed to protrude toward the sealing member side (the side away from the energy storage element) relative to the second region. However, the more the second conductive portion is designed to be easily deformed, the smaller the spring constant k1 is, and the resonance frequency f is. n Therefore, in order to maintain the resonant frequency f at a high n , it can be set as k2>k1.

[0059] The collector plate (first collector plate and second collector plate) having the first conductive portion and the second conductive portion described above can be a primary battery or a secondary battery, and can adopt any structure of a storage device regardless of the structure of the positive electrode and the negative electrode. The storage device of one embodiment of the present disclosure is suitable for being configured as a non-aqueous electrolyte secondary battery, an alkaline storage battery, or a capacitor, for example, and contributes to the high output of the non-aqueous electrolyte battery. The non-aqueous electrolyte battery includes a lithium ion secondary battery, an all-solid battery, and the like.

[0060] Hereinafter, the power storage device according to one embodiment of the present disclosure will be specifically described with reference to the drawings, taking as an example a case where the power storage device is used in a lithium ion secondary battery as an example of the power storage device.

[0061] Figure 1A and Figure 1B It is a diagram showing an example of the structure of a current collector plate according to one embodiment of the present disclosure. Figure 1A is a plan view showing the appearance of the current collector plate 14, Figure 1B This is a stereoscopic view of the collector plate 14 viewed from the first main surface side (the opposite side to the surface bonded to the storage cell). In a preferred embodiment, the collector plate 14 is disposed between the storage cell and the sealing member, and can be used to electrically connect one electrode (first electrode) of the storage cell to the terminal portion of the sealing member. The collector plate 14 can be a first collector plate or a positive collector plate.

[0062] The current collector plate 14 has a first main surface S1 and a second main surface S2 opposite to the first main surface S1. The current collector plate 40 is, for example, a metal plate, which can be punched into a predetermined shape and then processed into a concave-convex shape by press forming. Figure 1A and Figure 1B In the example of FIG. 1 , the collector plate 14 is roughly in the shape of a circular plate, but a through hole or a notch is formed in a part of the region in order to form the first conductive portion and the second conductive portion. The first main surface S1 is opposite to the bottom of the sealing member or the housing in the manufactured storage device. The second main surface S2 is opposite to the storage unit in the manufactured storage device.

[0063] The collector plate 14 has a first region 14A in its central portion and a second region 14B in the outer peripheral portion outside the first region 14A. When the collector plate is arranged in the housing, for example, the first region 14A is located at the center of the housing or the center of the storage cell, and the second region 14B extends from the center toward the housing cylinder. The plurality of second regions 14B may be separated from each other and extend radially in a radial direction away from the central first region 14A.

[0064] The first region 14A is electrically connected to an external terminal of the sealing member or the housing on the first main surface S1 side. The second region 14B is bonded to the storage unit on the second main surface S2 side. Figure 1B In order to facilitate the bonding with the power storage unit, the second region 14B may protrude toward the second main surface S2. Similarly, in order to facilitate the electrical connection with the external terminal, the first region 14A may protrude toward the first main surface S1.

[0065] The first conductive portion 15A connects the first region 14A and the second region 14B. Figure 1A and Figure 1B In the example of FIG. 1 , the first conductive portion 15A is a region with the smallest width sandwiched between the ends in the longitudinal direction of the plurality of slits 16 formed along the contour of the first region 14A.

[0066] The second conductive portion 15B connects the first region 14A and the second region 14B in the same manner as the first conductive portion 15A. The first conductive portion 15A forms a first conductive path 18A connecting the first region 14A and the second region 14B, and the second conductive portion 15B forms a second conductive path 18B connecting the first region 14A and the second region 14B. Figure 1A In FIG. 1 , the first conductive path 18A and the second conductive path 18B are respectively indicated by arrows directed from the second region 14B toward the first region 14A.

[0067] The first conduction path 18A and the second conduction path 18B form independent current paths, respectively. In the normal use state (the internal pressure of the power storage device is below the first pressure) when the first conduction portion 15A is not broken, the current flows in parallel through the first conduction path 18A and the second conduction path 18B. Among them, the path length between the first area 14A and the second area 14B of the first conduction path 18A is short and the resistance is low. On the other hand, the second conduction path 18B restricts the flow direction of the current through the slit 17 to form a curved conduction path, so the conduction path becomes longer and generally the resistance becomes higher.

[0068] For example, the resistance of the first conductive portion 15A may be lower than the resistance of the second conductive portion 15B. The difference between the first conductive path 18A and the second conductive path 18B is whether it passes through the first conductive portion 15A or the second conductive portion 15B halfway from the second region 14B to the first region 14A, and the other paths are substantially the same. Therefore, when the resistance of the first conductive portion 15A is lower than the resistance of the second conductive portion 15B, the resistance of the first conductive path 18A is lower than the resistance of the second conductive path 18B. Moreover, in the state where the first conductive portion 15A is not broken, the current flows in parallel through both the first conductive path 18A and the second conductive path 18B, but in the state where the first conductive portion 15A is broken, the current flows only in the second conductive path 18B. Therefore, by comparing the resistance of the collector plate 14 in the state where the first conductive portion 15A is not broken and the resistance of the collector plate 14 after the break, the relationship between the resistance of the first conductive portion 15A and the resistance of the second conductive portion 15B can be known. When the resistance of the collector plate 14 in the unbroken state of the first conductive portion 15A is lower than that of the collector plate 14 after the rupture, it can be said that the resistance of the first conductive portion 15A is lower than that of the second conductive portion 15B.

[0069] When the internal pressure of the power storage device increases, the side of the collector plate 14 closer to the center protrudes further toward the first main surface S1 than the peripheral side, and is deformed like expansion. At this time, the power storage unit is joined to the collector plate 14 in the second region 14B provided on the peripheral portion of the collector plate 14, so in the power storage device using the conventional collector plate, the collector plate and the joined part are sometimes peeled off with the deformation of the second region. However, in the power storage device using the collector plate of the present embodiment, the first conductive portion is broken as the internal pressure increases, thereby preventing the peeling of the joint between the power storage unit and the collector plate.

[0070] Figure 2 This is a perspective view of the collector plate 14 when the internal pressure of the case of the power storage device exceeds the first pressure and the first conductive portion 15A is broken, as viewed from the first main surface side (the opposite side to the surface bonded to the power storage cell). As the first conductive portion 15A is broken, the second conductive portion 15B is deformed (elastic deformation or plastic deformation), and the collector plate is deformed in such a way that the first region 14A protrudes toward the external terminal side (the side away from the power storage cell). At this time, the deformation of the second region 14B is suppressed, so that the bond separation between the power storage cell and the collector plate in the second region 14B can be suppressed.

[0071] The first pressure may be a pressure lower than a valve operating pressure at which the explosion-proof mechanism of the electrical storage device operates. The first pressure may be controlled to a desired pressure by reducing the film thickness of a portion of the first conductive portion 15A to form a thin-walled portion.

[0072] Figure 3A and Figure 3BIt is a diagram showing another example of the structure of the current collector plate according to one embodiment of the present disclosure. Figure 3A is a plan view showing the appearance of the current collector plate 24, Figure 3B This is a perspective view of the collector plate 24 viewed from the first main surface side (the opposite side to the surface bonded to the storage cell). In a preferred embodiment, the collector plate 24 is disposed between the storage cell and the bottom of the housing, and can be used to electrically connect the other electrode (second electrode) of the storage cell to the housing. The collector plate 24 can be a second collector plate or a negative collector plate.

[0073] The collector plate 24 is equivalent to the collector plate 14 except that the structure of the second conductive portion 15B is changed. The structure of the collector plate 24 other than the second conductive portion is the same as that of the collector plate 14, so the description is omitted or simplified. As long as there is no technical contradiction, a part of the structure of the collector plate 14 can be applied to the collector plate 24.

[0074] The collector plate 24 has a first region 24A in its central portion, similarly to the collector plate 14, and a second region 24B in the outer peripheral portion outside the first region 24A. The first region 24A is electrically connected to an external terminal of a sealing member or a housing on its first main surface S1 side. The second region 24B is joined to the storage cell on the second main surface S2 side.

[0075] The first conductive portion 25A and the second conductive portion 25B connect the first region 24A and the second region 24B, respectively. Figure 3A and Figure 3B In the example of FIG. 1 , the first conductive portion 15A is a region sandwiched by the ends in the longitudinal direction of a plurality of slits 26 formed along the contour of the first region 14A.

[0076] The first conductive portion 25A forms a first conductive path 28A connecting the first region 24A and the second region 24B, and the second conductive portion 25B forms a second conductive path 28B connecting the first region 24A and the second region 24B. The first conductive path 28A and the second conductive path 28B form independent current paths. The path length between the first region 24A and the second region 24B of the first conductive path 28A is short, and the resistance is low. On the other hand, the path length of the second conductive path 28B is long, and the resistance generally becomes high.

[0077] Figure 4This is a stereoscopic view of the collector plate 24 when the internal pressure of the power storage device exceeds the first pressure and the first conductive portion 25A is broken, viewed from the first main surface side (the opposite side to the surface where the bonding with the power storage unit is formed). As the first conductive portion 25A is broken, the second conductive portion 25B is deformed (elastic deformation or plastic deformation), and the collector plate is deformed in such a way that the first region 24A protrudes toward the external terminal side (the side away from the power storage element). At this time, the deformation of the second region 24B is suppressed, so that the bonding and peeling between the power storage unit and the collector plate in the second region 24B can be suppressed.

[0078] On the other hand, when compared with the collector plate 14, the collector plate 24 has a different shape of the second conductive portion (more specifically, the slit 17 is not provided), and the rigidity of the second conductive portion 25B when the first conductive portion is broken is greater than that of the second conductive portion 15B in the collector plate 14, and the second conductive portion 25B is difficult to deform. Therefore, with respect to the axial vibration, the second conductive portion acts as a spring to suppress the vibration of the storage unit in the storage device. The spring constant of the collector plate 24 with respect to the axial vibration when the first conductive portion is broken is greater than the spring constant of the collector plate 14 with respect to the axial vibration when the first conductive portion is broken. When the collector plate 14 and the collector plate 24 are combined and used in the storage device, it is preferred that the collector plate 14 with a small spring constant is arranged on the side opposite to the sealing member, and the collector plate 24 with a large spring constant is arranged on the side opposite to the bottom of the housing.

[0079] Figure 5 It is a longitudinal sectional view showing the structure of an electric storage device (lithium ion secondary battery) 200 in which the current collector plates 14 and 24 are arranged.

[0080] The power storage device 200 includes: a wound element (power storage unit) 100, in which a positive electrode 10 and a negative electrode 20 are wound with a separator 30 interposed therebetween to form a columnar shape; a non-aqueous electrolyte (not shown); a metal bottomed case 210 for accommodating the wound element 100 and the non-aqueous electrolyte; a sealing rubber 220 for sealing an opening of the case 210; a current collector 14; and a terminal 230. The sealing rubber and the terminal 230 constitute a sealing member.

[0081] The sealing rubber 220 has a through hole in the center, and a terminal 230 is inserted into the through hole. One end of the terminal 230 is electrically connected to the collector plate (positive electrode collector plate) 14. The other end of the terminal 230 is exposed to the outside of the battery 200 and serves as an external terminal of the battery 200 (in the Figure 5 In the example, it is the external positive terminal).

[0082] The sealing rubber 220 is pressed through the side surface (tube) 210a of the housing 210, and the interior of the housing 210 is sealed by riveting the opening end of the housing 210 to the sealing rubber 220. The curling portion 210b is formed at the opening end of the housing 210 by riveting.

[0083] The power storage device 200 can be manufactured by accommodating a wound element, a current collector plate, and a sealing rubber stacked in this order in a case, and then riveting an open end of the case to the sealing rubber to seal the opening of the case, thereby simplifying the manufacturing process.

[0084] In the power storage device 200, a sealing member that allows the terminal 230 to be inserted into the sealing rubber 220 is used to seal the opening of the housing 210. At this time, one end of the terminal 230 can also be welded to the collector plate (positive collector plate) 14 in the first area 14A, and one end of the terminal 230 is electrically connected to the collector plate (positive collector plate) 14. The sealing method of the opening of the housing 210 is not limited to the above example, and a sealing plate that functions as an external terminal and a gasket covering the outer peripheral edge of the sealing plate can also be used. In this case, the method of electrically connecting the sealing plate to the collector plate is not particularly limited, and the first area of ​​the collector plate can be directly connected to the sealing plate, or it can be done via an internal lead.

[0085] The non-aqueous electrolyte has lithium ion conductivity and includes a lithium salt and a non-aqueous solvent in which the lithium salt is dissolved.

[0086] The positive electrode 10 is in the form of a long sheet, and includes a positive electrode collector and a positive electrode active material layer carried thereon. The positive electrode active material layer is formed on both sides of the positive electrode collector. However, a positive electrode collector exposure portion 11x without a positive electrode active material layer may be formed at one end of the positive electrode collector along the length direction. The positive electrode collector exposure portion 11x is exposed at one end face of the wound element 100, and the positive electrode is electrically connected to the collector plate 14 via the positive electrode collector exposure portion 11x. The positive electrode collector exposure portion 11x is connected to the collector plate 14, for example, by welding. On the other hand, the other end of the positive electrode collector along the length direction is covered by an insulating layer 13.

[0087] The negative electrode 20 is in the form of a long sheet, and includes a negative electrode collector and a negative electrode active material layer carried thereon. The negative electrode active material layer is formed on both sides of the negative electrode collector. However, a negative electrode collector exposure portion 21x having no negative electrode active material layer is formed at one end portion of the negative electrode collector along the length direction (the end portion on the opposite side to the positive electrode collector exposure portion 11x). The negative electrode collector exposure portion 21x is exposed at the other end face of the wound element 100, and the negative electrode is electrically connected to the collector plate (negative electrode collector plate) 24 via the negative electrode collector exposure portion 21x. The negative electrode collector exposure portion 21x is connected to the collector plate 24, for example, by welding. On the other hand, the other end portion of the negative electrode collector along the length direction is covered by an insulating layer 23. The collector plate 24 is welded to a welding member 25 provided on the inner bottom surface of the housing 210. Therefore, the housing 210 functions as an external negative terminal.

[0088] (Sealing rubber)

[0089] By using a rubber material as a sealing member, a stable sealing resilience can be obtained, and the airtightness of the power storage device is improved. In addition, by forming the convex portion with a rubber material, the convex portion deforms when it contacts the collector and is pressed, and the component tolerance and assembly tolerance can be absorbed. The sealing rubber with a convex portion is manufactured, for example, by a molding technology such as compression molding.

[0090] On the other hand, the rubber material is easily deformed in response to the increase in internal pressure, and therefore sometimes lacks rigidity from the perspective of suppressing expansion. In order to improve the rigidity of the sealing rubber and achieve both high sealing resilience and suppression of expansion, the sealing rubber may also be a laminated structure having at least two layers of a rubber material layer (e.g., a butyl rubber layer) and a fluororesin layer. In this case, the convex portion is provided on the rubber material layer.

[0091] The Young's modulus of the rubber material layer also depends on the ambient temperature, but may be in the range of 4 MPa to 80 MPa. In contrast, the Young's modulus of the fluororesin may be a general value of 0.4 GPa or more.

[0092] The sealing rubber can be composed of a single layer of a rubber material layer including a rubber material, or a multilayer structure of a rubber material layer and a fluororesin layer. As the rubber material, butyl rubber (isobutylene-isoprene copolymer) (IIR) is preferred. Butyl rubber can obtain stable elasticity by crosslinking with peroxide or resin, and can stably obtain sealing resilience. Butyl rubber has low gas permeability compared to other rubber materials and high insulation, so even if it is stored for a long time, the performance of the storage device can be maintained high.

[0093] As the material of the fluororesin layer, PTFE (polytetrafluoroethylene), PVDF (polyvinylidene fluoride), PFA (perfluoroalkoxyalkane), ETFE (ethylene-tetrafluoroethylene copolymer), FEP (perfluoroethylene-propylene copolymer) are preferred. When forming a multilayer structure of a butyl rubber layer and a fluororesin layer, in order to improve the adhesion of the interface with the rubber material layer, it is preferred to roughen the surface of the butyl rubber layer side of the fluororesin layer by corona treatment, plasma treatment, sodium treatment, coating with an organic solvent dissolved with active sodium, etc., and perform compression molding under the state of improving the adhesion with the butyl rubber layer.

[0094] (Current collector)

[0095] The material constituting the collector plate is determined according to the material constituting the positive electrode and the negative electrode. For example, in the case of a negative electrode collector plate used as a lithium ion secondary battery, the material of the collector plate is, for example, copper, copper alloy, nickel, stainless steel, etc. The material of the negative electrode collector plate may be the same as the material of the negative electrode collector. For example, in the case of a positive electrode collector plate used as a lithium ion secondary battery, the material of the collector plate is, for example, aluminum, aluminum alloy, titanium, stainless steel, etc. The material of the positive electrode collector plate may be the same as the material of the positive electrode collector.

[0096] The exposed portion of the current collector and the current collector plate can be joined by laser welding, for example, by irradiating the current collector plate with laser light at multiple locations radially from the side opposite to the end surface of the wound element (ie, the side facing the sealing rubber).

[0097] (positive electrode)

[0098] The positive electrode current collector uses a sheet of metal material. The sheet of metal material can be any metal foil, porous metal, etched metal, etc. As the metal material, aluminum, aluminum alloy, nickel, titanium, etc. can be used. The thickness of the positive electrode current collector is, for example, 10 μm to 100 μm.

[0099] The positive electrode active material layer includes, for example, a positive electrode active material, a conductive material, and a binding material. The positive electrode active material layer is obtained, for example, by coating a positive electrode composite material slurry including a positive electrode active material, a conductive material, and a binding material on both sides of a positive electrode current collector, and then rolling the coating after drying. The positive electrode active material is a material for embedding and de-embedding lithium ions. Examples of the positive electrode active material include lithium-containing transition metal oxides, transition metal fluorides, polyanions, fluorinated polyanions, transition metal sulfides, and the like.

[0100] In the case where the power storage device is a capacitor such as a lithium ion capacitor or a double-layer capacitor, the positive electrode active material layer may include a positive electrode active material reversibly doped with anions. When anions are adsorbed on the positive electrode active material, a double layer is formed, showing capacity. The positive electrode may be a polarized electrode, or an electrode having the properties of a polarized electrode and a Faraday reaction that also contributes to capacitance. The positive electrode active material is, for example, a carbon material, a conductive polymer, and the like.

[0101] As the conductive polymer, π-conjugated polymers are preferred. As π-conjugated polymers, for example, polypyrrole, polythiophene, polyfuran, polyaniline, polythiopheneethylene, polypyridine or derivatives thereof can be used. They can be used alone or in combination of two or more. The weight average molecular weight of the conductive polymer is, for example, 1000 to 100000. It should be noted that the derivative of the π-conjugated polymer refers to a polymer with a π-conjugated polymer such as polypyrrole, polythiophene, polyfuran, polyaniline, polythiopheneethylene, polypyridine as the basic skeleton. For example, polythiophene derivatives include poly(3,4-ethylenedioxythiophene) (PEDOT) and the like.

[0102] As the carbon material, a porous carbon material is preferred, for example, activated carbon, a carbon material exemplified as a negative electrode active material (for example, non-graphitizable carbon) is preferred. As the raw material of the activated carbon, for example, wood, coconut shell, coal, asphalt, phenolic resin, etc. can be cited. The activated carbon is preferably activated.

[0103] (negative electrode)

[0104] The negative electrode current collector uses a sheet of metal material. The sheet of metal material can be any metal foil, porous metal, etched metal, etc. As the metal material, copper, copper alloy, nickel, stainless steel, etc. can be used. The thickness of the negative electrode current collector is, for example, 10 μm to 100 μm.

[0105] The negative electrode active material layer includes, for example, a negative electrode active material, a conductive material, and a binder. The negative electrode active material layer is obtained, for example, by coating a negative electrode composite material slurry including a negative electrode active material, a conductive material, and a binder on both sides of a negative electrode current collector, and then rolling the coating after drying. The negative electrode active material is a material that embeds and de-embeds lithium ions. Examples of the negative electrode active material include carbon materials, metal compounds, alloys, ceramic materials, and the like. Examples of the carbon material include graphite, hard carbon, and the like.

[0106] (Partition)

[0107] As the separator, for example, a microporous film made of a resin such as polyolefin, a woven fabric, a nonwoven fabric, etc. can be used. The thickness of the separator is, for example, 10 to 300 μm, preferably 10 to 40 μm.

[0108] (Non-aqueous electrolyte)

[0109] The non-aqueous electrolyte has lithium ion conductivity and includes a lithium salt and a non-aqueous solvent in which the lithium salt is dissolved.

[0110] [Method for detecting the state of an electric storage device]

[0111] In a method for detecting the state of an electric storage device according to an embodiment of the present disclosure, in the above-mentioned electric storage device, the state of the electric storage device is detected by detecting a change in the electrical characteristics of the electric storage device caused by the rupture of the first conductive portion. Before and after the rupture of the first conductive portion, the electrical characteristics of the collector plate change, and thus the electrical characteristics of the electric storage device also change. By measuring the change in the electrical characteristics, it is possible to know whether the first conductive portion has been broken, that is, whether a phenomenon causing an increase in the internal pressure of the case of the electric storage device has occurred, without disassembling the device.

[0112] The electrical property to be measured may be resistance. The method for detecting the state of the electrical storage device may detect the state of the electrical storage device by detecting a change in the internal resistance of the electrical storage device caused by the breakage of the first conductive portion.

[0113] In addition, when the first conductive portion is broken, for example Figure 1A As shown, the current through the curved second conductive path 18B flows to the collector plate 14, so the inductance or capacitance tends to increase accordingly. The state detection method of the storage device can also detect the state of the storage device by detecting the change in the inductance or capacitance of the storage device caused by the breakage of the first conductive part. In addition, the state detection method of the storage device can also detect the change in the impedance of the storage device caused by the breakage of the first conductive part. In this case, an AC voltage is applied to the storage device to measure the impedance.

[0114] Postscript

[0115] The following techniques are disclosed through the description of the above embodiments.

[0116] (Technology 1)

[0117] A power storage device comprises: a power storage unit; a bottomed cylindrical shell, which accommodates the power storage unit and has an opening at one end; a sealing member, which seals the opening; and a collector plate, wherein the collector plate comprises: a first region, which is electrically connected to an external terminal, which is an external terminal possessed by the sealing member or the shell; a second region, which is joined to the power storage unit; one or more first conductive parts, which connect the first region with the second region; and one or more second conductive parts, which connect the first region with the second region, wherein the resistance of the first conductive part is different from the resistance of the second conductive part.

[0118] (Technique 2)

[0119] According to the power storage device of technology 1, the resistance of the first conductive section is lower than the resistance of the second conductive section.

[0120] (Technique 3)

[0121] In the power storage device according to technology 1 or 2, the length of the first conductive portion is shorter than the length of the second conductive portion.

[0122] (Technique 4)

[0123] According to any one of techniques 1 to 3, the minimum width of the first conductive portion is narrower than the minimum width of the second conductive portion.

[0124] (Technique 5)

[0125] According to the power storage device of any one of techniques 1 to 4, when the internal pressure in the case exceeds a predetermined first pressure, at least a portion of the first conductive portion of the collector plate is broken, and the second conductive portion is not broken.

[0126] (Technique 6)

[0127] According to the power storage device of technology 5, when the internal pressure exceeds the first pressure, the second conductive portion is deformed in such a manner that the first region protrudes toward the external terminal in the axial direction of the case as the first conductive portion breaks.

[0128] (Technique 7)

[0129] According to any one of techniques 1 to 6, a plurality of slits are intermittently formed along the contour of the first region, and the first conductive portion includes a minimum width between ends of the plurality of slits in the longitudinal direction.

[0130] (Technology 8)

[0131] According to any one of techniques 1 to 7, the first region includes a central portion of the current collector plate, and the second region is provided at an outer peripheral portion outside the central portion.

[0132] (Technique 9)

[0133] According to the electric storage device of any one of techniques 1 to 8, the first region is electrically connected to a terminal portion of the sealing member, and the second region is joined to a first electrode of the electric storage cell.

[0134] (Technology 10)

[0135] According to the power storage device of technology 9, the first region is joined to the terminal portion by welding.

[0136] (Technology 11)

[0137] According to the power storage device of any one of techniques 1 to 10, the first region is electrically connected to the case, and the second region is joined to the second electrode of the power storage cell.

[0138] (Technology 12)

[0139] The electrical storage device according to any one of Techniques 1 to 11 comprises a pair of collector plates, wherein in a first collector plate of one of the pair of collector plates, the first region is electrically connected to the terminal portion of the sealing component, and the second region is joined to the first electrode of the electrical storage unit, and in a second collector plate of the other of the pair of collector plates, the first region is electrically connected to the shell, and the second region is joined to the second electrode of the electrical storage unit.

[0140] (Technology 13)

[0141] According to the power storage device of technology 12, in the first current collecting plate and the second current collecting plate, at least one of the first conductive portion and the second conductive portion has a different shape.

[0142] (Technology 14)

[0143] According to the power storage device of technology 12 or 13, the spring constant of the axial vibration of the case of the second collector plate when the first conductive portion is broken is greater than the spring constant of the axial vibration of the first collector plate when the first conductive portion is broken.

[0144] (Technology 15)

[0145] A power storage device comprises: a power storage unit; a shell with a bottom and a cylindrical shape, which accommodates the power storage unit and has an opening at one end; a sealing member, which seals the opening; and a collector plate, wherein the collector plate comprises: a first region, which is electrically connected to an external terminal, which is an external terminal possessed by the sealing member or the shell; a second region, which is joined to the power storage unit; one or more first conductive portions, which connect the first region with the second region; and one or more second conductive portions, which connect the first region with the second region, wherein if the internal pressure in the shell exceeds a specified first pressure, at least a portion of the first conductive portion of the collector plate breaks, while the second conductive portion does not break.

[0146] (Technology 16)

[0147] A method for detecting a state of an electric storage device, in the electric storage device according to any one of techniques 1 to 15, detects the state of the electric storage device by detecting a change in an electrical characteristic of the electric storage device caused by a break in the first conductive portion.

[0148] (Technology 17)

[0149] According to the method for detecting the state of the electric storage device described in the sixth aspect, the state of the electric storage device is detected by detecting a change in the internal resistance of the electric storage device caused by the breakage of the first conductive portion.

[0150] Industrial availability

[0151] The power storage device of the present disclosure can achieve high output and is therefore suitable for, for example, vehicle-mounted use.

[0152] The preferred embodiments of the present invention at the present time are described, but such disclosure is not limited to interpretation. By reading the above disclosure, a person skilled in the art in the technical field of the present invention can clearly understand various modifications and changes. Therefore, it should be interpreted that the attached claims do not depart from the true spirit and scope of the present invention and include all modifications and changes.

[0153] Explanation of symbols

[0154] 100 wound elements (power storage units)

[0155] 10 Positive electrode

[0156] 11x Positive electrode current collector exposed part

[0157] 13 Insulation layer

[0158] 14 collector plate (positive collector plate)

[0159] 14A First Area

[0160] 14B Second Area

[0161] 15A first conduction section

[0162] 15B second conductive portion

[0163] 16, 17 slits

[0164] 18A first conduction path

[0165] 18B Second conduction path

[0166] 20 negative electrode

[0167] 21x Negative electrode current collector exposed part

[0168] 23 Insulation layer

[0169] 24 collector plate (negative collector plate)

[0170] 24A First Area

[0171] 24B Second Area

[0172] 25A first conduction section

[0173] 25B second conductive portion

[0174] 26 Slits

[0175] 28A first conduction path

[0176] 28B Second conduction path

[0177] 30 partitions

[0178] 200Electrical storage equipment

[0179] 210 Shell

[0180] 210a Side part

[0181] 210b curling part

[0182] 220 sealing rubber

[0183] 230 terminal

Claims

1. An electric storage device comprising: Power storage unit; A bottomed cylindrical housing, which accommodates the power storage unit and has an opening at one end; a sealing member for sealing the opening; and Collector plate, The collector plate comprises: The first region is electrically connected to an external terminal, which is an external terminal of the sealing member or the housing; a second region connected to the power storage unit; one or more first conductive parts connecting the first region and the second region; and One or more second conductive parts connect the first region and the second region, The resistance of the first conductive portion is different from the resistance of the second conductive portion.

2. The power storage device according to claim 1, The first conductive portion has a lower resistance than the second conductive portion.

3. The power storage device according to claim 1, The length of the first conductive portion is shorter than the length of the second conductive portion.

4. The power storage device according to claim 1, A minimum width of the first conductive portion is narrower than a minimum width of the second conductive portion.

5. The power storage device according to claim 1, When the internal pressure in the case exceeds a predetermined first pressure, at least a portion of the first conductive portion of the collector plate is broken, but the second conductive portion is not broken.

6. The power storage device according to claim 5, When the internal pressure exceeds the first pressure, the second conductive portion is deformed in such a manner that the first region protrudes toward the external terminal in the axial direction of the case as the first conductive portion breaks.

7. The power storage device according to any one of claims 1 to 6, A plurality of slits are intermittently formed along the contour of the first region, The first conductive portion includes a minimum width between end portions of the plurality of slits in the length direction.

8. The power storage device according to any one of claims 1 to 6, The first region includes a central portion of the collector plate, The second region is provided in the outer peripheral portion outside the central portion.

9. The power storage device according to any one of claims 1 to 6, The first region is electrically connected to a terminal portion of the sealing member, The second region is joined to the first electrode of the power storage cell.

10. The power storage device according to claim 9, The first region is joined to the terminal portion by welding.

11. The power storage device according to any one of claims 1 to 6, The first region is electrically connected to the housing, The second region is joined to a second electrode of the power storage cell.

12. The power storage device according to any one of claims 1 to 6, A pair of current collecting plates is provided, In a first current collector plate of one of the pair of current collector plates, the first region is electrically connected to a terminal portion of the sealing member, and the second region is bonded to a first electrode of the power storage cell. In the other of the pair of the current collector plates, the second current collector plate, the first region is electrically connected to the case, and the second region is joined to the second electrode of the power storage cell.

13. The power storage device according to claim 12, In the first current collecting plate and the second current collecting plate, at least one of the first conductive portion and the second conductive portion has a different shape.

14. The power storage device according to claim 12, A spring constant of the second current collector plate with respect to vibration in the axial direction of the case when the first conductive portion is broken is greater than a spring constant of the first current collector plate with respect to vibration in the axial direction when the first conductive portion is broken.

15. An electric storage device comprising: Power storage unit; A bottomed cylindrical housing, which accommodates the power storage unit and has an opening at one end; a sealing member for sealing the opening; and Collector plate, The collector plate comprises: The first region is electrically connected to an external terminal, which is an external terminal of the sealing member or the housing; a second region connected to the power storage unit; one or more first conductive parts connecting the first region and the second region; and One or more second conductive parts connect the first region and the second region, When the internal pressure in the case exceeds a predetermined first pressure, at least a portion of the first conductive portion of the collector plate is broken, but the second conductive portion is not broken.

16. A method for detecting the state of an electric storage device, In the power storage device according to any one of claims 1 to 6, This state detection method detects the state of the power storage device by detecting a change in the electrical characteristics of the power storage device caused by the breakage of the first conductive portion.

17. The method for detecting the state of an electric storage device according to claim 16, The state of the power storage device is detected by detecting a change in the internal resistance of the power storage device caused by the breakage of the first conductive portion.

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