Power storage device

Abstract

To provide a power storage device that achieves enhanced reliability concerning airtightness, while having an insulating resin member formed integrally with a case member and a terminal member by insert molding.SOLUTION: A power storage device 1 includes a case member 30 having a terminal insertion hole 30h, a terminal member 50, and a resin member 70 made of an insulating resin material 70R. The resin material includes glass fibers GF. In the resin member, when the resin member is tomographically imaged using X-ray micro-CT, and an average orientation direction MDR of the glass fibers is obtained for each rectangular parallelepiped 3D mesh SM included in the resin member, and when declinations θxy,θyz,θzx of three direction components Mxy, Myz, Mzx formed by projecting three planes Pxy, Pyz, Pzx having average orientation directions perpendicular to each other are obtained, standard deviations σxy, σyz, σzx, of the frequency distribution of the three declinations, obtained for all 3D meshes SM included in the resin member each have a size of 5 deg or more.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an electricity storage device. [Background technology]

[0002] A known method involves providing a terminal insertion hole in a cover member of a case member of an electricity storage device, inserting a terminal member into the terminal insertion hole, and then integrally and airtightly fixing the cover member and the terminal member to each other using an insulating resin member by insert molding (see Patent Document 1).

[0003] In the resin material of such resin members, the thermal expansion coefficient of the resin material is made closer to that of the metal that makes up the case member and terminal member, and glass fibers or the like are mixed into thermoplastic resins such as PPS in order to improve the bending strength of the resin material. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-44303 Summary of the Invention [Problem to be solved by the invention]

[0005] However, glass fibers in resin materials tend to align with the flow of molten resin material that occurs during insert molding, and after cooling and solidification, the glass fibers tend to be oriented in a specific direction. On the other hand, resin materials with oriented glass fibers have high mechanical strength, such as bending strength, in the direction (MD) along which the molten resin flows and the glass fibers extend. However, mechanical strength in the direction perpendicular to this (TD) is not significantly improved and is relatively low compared to the MD. In other words, resin components made of resin materials with oriented glass fibers have anisotropy in their mechanical strength, which can lead to cracks in weaker areas compared to resin components with reduced anisotropy, reducing the reliability of the energy storage device, such as its airtightness.

[0006] The present invention has been made in consideration of this current situation, and provides an electricity storage device that has an insulating resin member formed integrally with a case member and terminal member by insert molding, but which has enhanced reliability by using a resin member that suppresses the anisotropy of the resin material. [Means for solving the problem]

[0007] (1) One aspect of the present invention for solving the above problem is an electricity storage device including a case member having a terminal insertion hole, terminal members inserted into the terminal insertion hole, and a resin member made of an insulating resin material and hermetically welded to the case member and the terminal member, respectively, to fix the terminal members to the case member while insulating them from the case member, wherein the resin material constituting the resin member contains glass fiber, and the resin member is subjected to tomography using an X-ray micro-CT to obtain an average orientation direction of the glass fibers for each rectangular solid three-dimensional mesh included in the resin member, and the deviation angles of three directional components obtained by projecting this average orientation direction onto three mutually orthogonal planes, the standard deviation of the frequency distribution of the three deviation angles obtained for all the three-dimensional meshes included in the resin member is 5 degrees or more.

[0008] For example, if a resin sample is formed by pouring a resin material in a specific direction and solidifying it, and the average orientation direction is obtained in the same manner as described above, and the deviation angles of the three directional components of this average orientation direction are obtained, and the standard deviation of their frequency distribution is calculated, the standard deviation (e.g., σyz) of the specific deviation angle (e.g., θyz) will be a small value. This is because the orientation of the glass fibers, and therefore the average orientation direction in a large number of three-dimensional meshes, is aligned in a specific direction, and the deviation angle of the average orientation direction has a high frequency within a narrow angle range, resulting in a small standard deviation of the frequency distribution.

[0009] In contrast, in this energy storage device, the standard deviations of the frequency distributions of the three deflection angles obtained for all three-dimensional meshes included in the resin member are all 5° or greater. In other words, cases where the standard deviation of the frequency distribution of any deflection angle is small, i.e., cases where the average orientation direction is consistent across the entire resin member, are excluded, and it can be said that the average orientation direction is inconsistent across the entire resin member. Therefore, in this energy storage device, a resin member with reduced anisotropy of the resin material is used, compared to when a resin member is used in which the standard deviation of the frequency distribution of any of the deviation angles in the average orientation direction is less than 5 degrees, resulting in an energy storage device with improved reliability.

[0010] Examples of the power storage device include secondary batteries such as lithium ion secondary batteries and sodium ion secondary batteries, and capacitors such as lithium ion capacitors. Furthermore, the metal forming the terminal members may be the same as the metal forming the case members (for example, both are made of the same aluminum), or may be different (for example, aluminum and copper).

[0011] In this technology, the average orientation direction MDR is projected onto three mutually orthogonal planes (e.g., the XY plane Pxy, the YZ plane Pyz, and the ZX plane Pzx) to obtain three directional components (e.g., the XY directional component Mxy, the YZ directional component Myz, and the ZX directional component Mzx). Next, the deflection angles of the three directional components are obtained. For example, of the three deflection angles, the deflection angle θxy is the angle between the XY directional component Mxy and the X-axis AX. Furthermore, the deflection angle θyz is the angle between the YZ directional component Myz and the Y-axis AY. Furthermore, the deflection angle θzx is the angle between the ZX directional component Mzx and the Z-axis AZ.

[0012] (2) In the electricity storage device according to (1) above, it is preferable that the standard deviation of the frequency distribution of the three deflection angles is 18 degrees or more.

[0013] In this energy storage device, the standard deviations of the frequency distributions of the three deviation angles obtained for all three-dimensional meshes included in the resin member are all 18 degrees or greater, which means that the average orientation direction is highly irregular when viewed across the entire resin member.

[0014] (3) The electricity storage device according to (1) or (2), wherein the case member is made of aluminum, the terminal member is a positive electrode terminal member made of aluminum, and the resin material constituting the resin member has an MD / TD average thermal expansion coefficient of 1.8 to 3.0 × 10 -5 It is recommended to use a storage device with a capacity of (1 / K).

[0015] In this energy storage device, the MD / TD average thermal expansion coefficient αMT of the resin material is set to αMT=1.8~3.0×10, which is close to the thermal expansion coefficient αAL of aluminum. -5 Therefore, it is possible to suppress the occurrence of stress in the resin member between the case member and the positive electrode terminal member due to the difference in thermal expansion between the case member and the positive electrode terminal member.

[0016] (4) The electricity storage device according to (1) or (2), wherein the case member is made of aluminum, the terminal member is a negative electrode terminal member made of copper, and the resin material constituting the resin member has an MD / TD average thermal expansion coefficient of 1.7 to 2.5 × 10 -5 (1 / K) It is recommended to use it as a storage device.

[0017] In this energy storage device, the MD / TD average thermal expansion coefficient of the resin material, αMT, is set to αm=2.1×10, which is intermediate between that of aluminum and copper. -5 (1 / K), αMT=1.7~2.5×10 -5 Therefore, it is possible to suppress the occurrence of stress in the resin member between the case member and the negative electrode terminal member due to the difference in thermal expansion between the case member and the negative electrode terminal member. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a perspective view of a battery according to an embodiment. [Figure 2] 1 is a longitudinal cross-sectional view of a battery according to an embodiment, taken along the battery height direction and the battery width direction. [Figure 3] 3 is a partially enlarged cross-sectional view showing the vicinity of a terminal insertion hole of a lid member of the battery according to the embodiment. FIG. [Figure 4] 4 is a cross-sectional view of the resin member according to the embodiment taken along the line CC in FIG. 3, showing the three-dimensional meshes and the average orientation direction superimposed thereon. FIG. [Figure 5] FIG. 10 is an explanatory diagram showing a test piece according to a reference embodiment, in which glass fibers in a resin material are aligned in the direction along the Y axis. [Figure 6] FIG. 10 is an explanatory diagram showing the relationship between the average orientation direction MDR, the deflection angles θxy, θyz, θzx, and the standard deviations σxy, σyz, σzx in a three-dimensional mesh. [Figure 7] 10 is a graph showing the frequency distribution of the deflection angle θxy in the resin member according to the embodiment. [Figure 8] 10 is a graph showing the frequency distribution of the deflection angle θyz in the resin member according to the embodiment. [Figure 9] 10 is a graph showing the frequency distribution of the deflection angle θzx in the resin member according to the embodiment. [Figure 10] 10 is a graph showing the frequency distribution of the deflection angle θxy in the test piece according to the reference embodiment. [Figure 11] 10 is a graph showing the frequency distribution of the deflection angle θyz in the test piece according to the reference embodiment. [Figure 12] 10 is a graph showing the frequency distribution of the deflection angle θzx in the test piece according to the reference embodiment. [Figure 13] 3 is a flowchart showing a manufacturing procedure for a battery according to an embodiment. [Figure 14] FIG. 1 is an exploded view of a battery according to an embodiment. [Figure 15] 3 is a cross-sectional view showing the formation of a cavity in an insert molding step in the manufacturing method of the battery according to the embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0019] (Embodiment) An embodiment of the present invention will be described below with reference to the drawings. Fig. 1 shows a perspective view of a battery (energy storage device) 1 according to this embodiment, and Fig. 2 shows a longitudinal cross-sectional view of the battery 1. Fig. 3 shows an enlarged partial cross-sectional view of the vicinity of the terminal insertion hole 30h of the lid member 30 of the lid assembly 15 of the battery 1. In the following description, the battery height direction AH, battery width direction BH, and battery thickness direction CH of the battery 1 will be defined as the directions shown in Figs. 1 and 2.

[0020] This battery 1 is a rectangular (rectangular) sealed lithium ion secondary battery that can be installed in vehicles such as hybrid cars, plug-in hybrid cars, and electric cars. The battery 1 is composed of a case 10, an electrode assembly 40 housed in the case 10, and positive and negative terminal members 50 fixed to the case 10 via resin members 70. The electrode assembly 40 is covered within the case 10 by a bag-shaped insulating holder 7 made of insulating film. The case 10 also contains an electrolyte 5, a portion of which is impregnated within the electrode assembly 40 and the remainder of which is collected at the bottom inside the case 10.

[0021] The case 10 is a rectangular box made of metal (aluminum in this embodiment), and is configured from a case body member 20 in the shape of a bottomed square cylinder with a rectangular opening 20c and accommodating an electrode assembly 40 therein, and a rectangular plate-shaped lid member 30 that closes the opening 20c of the case body member 20. The opening 20c of the case body member 20 and a peripheral edge 30f of the lid member 30 are hermetically welded all around. The lid member 30 is provided with a safety valve 11 that ruptures and opens when the internal pressure of the case 10 exceeds a valve opening pressure. The lid member 30 is also provided with a liquid inlet 30k, which is hermetically sealed with a disc-shaped liquid inlet plug 12 made of aluminum.

[0022] The electrode assembly 40 is a flat, cylindrical, wound type. Long, strip-shaped positive electrode plates 41 and negative electrode plates 42 are alternately stacked and wound with two long, strip-shaped separators 43 made of porous resin, and then compressed in the battery thickness direction CH to form a flattened shape. A positive current collector 40p is formed on one side BH1 (left side in FIG. 2 ) of the electrode assembly 40 in the battery width direction BH along the winding axis 40X, where the current collector foil of the positive electrode plate 41 overlaps in a spiral shape. This positive current collector 40p is welded to a positive terminal member 50P for electrical continuity. Furthermore, a negative current collector 40n is formed on the other side BH2 (right side in FIG. 2 ) of the electrode assembly 40 in the battery width direction BH, where the current collector foil of the negative electrode plate 42 overlaps in a spiral shape. This negative current collector 40n is welded to a negative terminal member 50N for electrical continuity.

[0023] The lid member 30 has rectangular terminal insertion holes 30h penetrating the lid member 30 near both ends of one side BH1 and the other side BH2 in the battery width direction BH. A positive electrode terminal member 50P made of aluminum is inserted into the terminal insertion hole 30h on the one side BH1, and the positive electrode terminal member 50P is airtightly fixed to the lid member 30 via a resin member 70 welded thereto, while being insulated from the lid member 30. Meanwhile, a negative electrode terminal member 50N made of copper is inserted into the terminal insertion hole 30h on the other side BH2, and the negative electrode terminal member 50N is airtightly fixed to the lid member 30 via a resin member 70 welded thereto, while being insulated from the lid member 30.

[0024] 1 and 2, the positive electrode terminal member 50P and the negative electrode terminal member 50N, which are terminal members 50, have shapes that are roughly mirror images of each other. The positive electrode terminal member 50P is made of an aluminum plate, and the negative electrode terminal member 50N is made of a copper plate, which has been cut and bent by a press.

[0025] The terminal members 50 (positive electrode terminal member 50P, negative electrode terminal member 50N) are located above the cover member 30 on the upper side AH1 in the battery height direction AH, and have a rectangular, flat top plate portion 50a extending in the battery width direction BH and the battery thickness direction CH, and a bent extension portion 50b that is bent at a right angle from the edge of the top plate portion 50a on one side CH1 in the battery thickness direction CH (the rear side in Figures 2 and 3) and extends to the lower side AH2 in the battery height direction AH. Furthermore, the terminal member 50 has a stepped extension portion 50c that is shifted from the bent extension portion 50b to the outer side BHO in the battery width direction BH (one side BH1 in the positive terminal member 50, and the other side BH2 in the negative terminal member 50; see Figure 2) in a stepped manner by approximately half the width dimension of the bent extension portion 50b and extends to the lower side AH2 in the battery height direction AH, and a connecting portion 50d that extends from the stepped extension portion 50c to the lower side AH2 in the battery height direction AH, bends at a bend 50db midway to the other side CH2 in the battery thickness direction CH (the front side in Figure 2), and further extends to the lower side AH2 in the battery height direction AH. The bent extension portion 50b, the stepped extension portion 50c, and the connecting portion 50d all have a rectangular cross section that is elongated in the battery width direction BH.

[0026] Of the terminal member 50, the bent extension portion 50b is inserted into the terminal insertion hole 30h of the cover member 30. In addition, the connection portion 50d of the positive electrode terminal member 50P is welded to the positive electrode current collector 40p of the electrode body 40, thereby extending the positive electrode potential of the positive electrode current collector 40p to the top plate portion 50a of the positive electrode terminal member 50P. Similarly, the connection portion 50d of the negative electrode terminal member 50N is welded to the negative electrode current collector 40n of the electrode body 40, thereby extending the negative electrode potential of the negative electrode current collector 40n to the top plate portion 50a of the negative electrode terminal member 50N.

[0027] The positive electrode terminal member 50P and the negative electrode terminal member 50N are each integrally fixed to the lid member 30 by a resin member 70 formed by insert molding to form the lid assembly 15 (see the upper part of FIG. 14). The resin member 70 of this embodiment is made of a resin material 70R containing a thermoplastic main resin (specifically, polyphenylene sulfide (PPS)), a thermoplastic elastomer, and glass fiber GF as a filler.

[0028] The resin member 70 is roughly divided into a top plate peripheral portion 71, an outer peripheral portion 72, an inner peripheral portion 73, an insertion hole filling portion 74, a step surrounding portion 75, and a gate portion 76 (see FIGS. 1 and 3). Of these, the top plate peripheral portion 71 is a rectangular annular portion located outside the planar direction of the top plate portion 50a of the terminal member 50, i.e., around the battery width direction BH and the battery thickness direction CH. The outer peripheral portion 72 is an annular portion located on a lower side AH2 of the top plate peripheral portion 71 and on an upper side AH1 of an annular peripheral portion 31 of the lid member 30 that surrounds the terminal insertion hole 30h. The inner peripheral portion 73 is an annular portion located on the lower side AH2 of the peripheral portion 31 of the lid member 30. The insertion hole filling portion 74 is an annular portion on the underside AH2 of the top plate peripheral portion 71, and is sandwiched between the inner peripheral surface 30hs of the terminal insertion hole 30h in the cover member 30 and the bent extending portion 50b of the terminal member 50. The step surrounding portion 75 is an annular portion that surrounds the step extending portion 50c of the terminal member 50 on the underside AH2 of the insertion hole filling portion 74 and on the underside AH2 of the cover member 30. The gate portion 76 is a portion into which molten resin material 70R is injected in a resin injection step S32 (see FIG. 13) described later, and protrudes in a semicircular arc convex shape from a position of the top plate peripheral portion 71 and the outer peripheral edge portion 72 that is biased toward one side CH1 in the battery thickness direction CH toward the inside BHI in the battery width direction BH (see FIG. 1).

[0029] As described above, the resin member 70 is formed by injecting molten resin material 70R into a cavity CV (FIG. 15) described later in a resin injection step S32 of the insert molding step S3 (see FIG. 13) described later. Specifically, the molten resin material 70R is injected from the upper side AH1 in the battery height direction AH toward the gate portion 76. From this gate portion 76, the molten resin material 70R spreads in various directions, such as to the lower side AH2 in the battery height direction AH, to the outer side BHO and inner side BHI in the battery width direction BH, and to the other side CH2 in the battery thickness direction CH, until it reaches various parts of the resin member 70 and solidifies. At this time, the molten resin material 70R traveling in various directions may meet, or may be hindered from flowing and move in a vortex, and so on. As it reaches various parts, the resin member 70 is formed.

[0030] The bonding and airtightness between the lid member 30 and the resin member 70 will be described. An annular, band-shaped lid seal outer roughened portion 31s1 is formed on the outer surface 30s1 facing the upper side AH1 of the annular peripheral portion 31 surrounding the terminal insertion hole 30h of the lid member 30, as shown by the bold line in FIG. 3. An annular, band-shaped lid seal inner roughened portion 31s2 is formed on the inner surface 30s2 facing the lower side AH2 of the peripheral portion 31, as shown by the bold line in FIG. 3. The lid seal outer roughened portion 31s1 and the lid seal inner roughened portion 31s2 are formed by intermittently irradiating a pulsed laser beam while moving the pulsed laser beam, resulting in a roughened surface consisting of numerous columnar nanopillars formed by particles derived from the metal (aluminum in this embodiment) constituting the lid member 30 linked together in a string-like pattern.

[0031] The outer roughened portion 31s1 of the lid seal and the inner roughened portion 31s2 of the lid seal are filled with a resin material 70R that forms the outer peripheral portion 72 and the inner peripheral portion 73 of the resin member 70. As a result, the resin member 70 is firmly fixed to the peripheral portion 31 of the lid member 30, and the interface between the peripheral portion 31 of the lid member 30 and the resin member 70 is sealed with high airtightness by the annular outer roughened portion 31s1 of the lid seal and the inner roughened portion 31s2 of the lid seal.

[0032] Next, the bonding and airtightness between the positive and negative electrode terminal members 50 and the resin member 70 will be described. In the positive and negative electrode terminal members 50, as shown by the dotted pattern and thick line in Fig. 3, the bent extending portion 50b is located near the terminal insertion hole 30h and has a band-like, annular portion that surrounds the terminal member 50, which is a first roughened portion 51. The first roughened portion 51 is a rectangular, annular, band-like roughened surface that is generally made up of four surfaces: an inner roughened end surface 51a facing the inner side BHI in the battery width direction BH, an outer roughened end surface 51b facing the outer side BHO in the battery width direction BH, and flat roughened portions 51c and 51d facing one side CH1 (the back side in Fig. 3) and the other side CH2 (the front side in Fig. 3) in the battery thickness direction CH. This first roughened portion 51 is also formed by intermittently irradiating a pulsed laser beam while moving it, and is a roughened surface consisting of a large number of columnar nanopillars formed by particles derived from the metal that makes up the terminal member 50 (aluminum for the positive terminal member 50P, copper for the negative terminal member 50N) linked together in a string-like pattern.

[0033] Furthermore, as described below, the first roughened portion 51 is also filled with resin material 70R that forms the insertion hole filling portion 74 of the resin member 70, and the insertion hole filling portion 74 of the resin member 70 is firmly fixed to the first roughened portion 51 at the bent extension portion 50b of the terminal member 50 with a long creepage distance in the width direction of the first roughened portion 51 (battery height direction AH in Figure 3).

[0034] Therefore, the interface between the bent extension portion 50b of the terminal member 50 and the insertion hole filling portion 74 of the resin member 70, and ultimately the interface between the terminal member 50 and the resin member 70, can maintain particularly good airtightness between the band-shaped, annular first roughened portion 51 and the insertion hole filling portion 74.

[0035] As will be described later, the lid assembly 15 is formed by injection molding the resin material 70R to integrally fix the lid member 30 and the pair of terminal members 50 inserted into the terminal insertion holes 30h with the resin material 70. However, since there is a difference in the thermal expansion coefficient between the metals (aluminum and copper in this embodiment) constituting the lid member 30 and the terminal members 50 and the resin material 70R, thermal stress occurs in each member when the temperature is lowered after molding due to the difference in thermal expansion.

[0036] In this embodiment, the MD / TD average thermal expansion coefficient αMT of the resin material 70R in the temperature range of −40 to 60° C. is αMT=1.8 to 3.0×10 -5 (1 / K). Specifically, αMT=2.0×10 -5 (1 / K). Therefore, the thermal expansion coefficient αAl (=2.5×10 -5 (1 / K)), and it is possible to suppress the occurrence of stress due to the difference in thermal expansion in the resin member 70 between the cover member 30 and the positive electrode terminal member 50P.

[0037] The MD / TD average thermal expansion coefficient αMT of the resin material 70R is the average of the thermal expansion coefficient in the MD direction (relatively small) and the thermal expansion coefficient in the TD direction (relatively large) of the resin material 70R in the temperature range of -40 to 60°C. In this embodiment, the resin material 70R contains glass fiber GF, and the glass fiber GF is oriented in the direction along the flow of the resin material 70R (MD direction). The thermal expansion coefficient of the glass fiber GF is smaller than that of the thermoplastic resin (PPS). Therefore, the thermal expansion coefficient of the resin material 70R is anisotropic, and the thermal expansion coefficient of the resin material 70R in the MD direction is relatively small due to the influence of the glass fiber GF. On the other hand, the thermal expansion coefficient of the resin material 70R in the TD direction is larger than the thermal expansion coefficient in the MD direction.

[0038] In this embodiment, the MD / TD average thermal expansion coefficient αMT of the resin material 70R is set to αMT=1.7 to 2.5×10 -5 (1 / K). Specifically, as mentioned above, αMT = 2.0 × 10 -5 (1 / K). Therefore, the thermal expansion coefficient αm (=2.1×10 -5 (1 / K)), and the occurrence of stress due to the difference in thermal expansion can be suppressed also in the resin member 70 between the cover member 30 and the negative electrode terminal member 50N.

[0039] In the battery 1 of this embodiment, as described above, the MD / TD average thermal expansion coefficient αMT of the resin material 70R constituting the resin member 70 is set to an appropriate value to suppress the generation of stress due to the thermal expansion difference. However, it is not possible to completely eliminate the generation of stress due to the thermal expansion difference.

[0040] As described above, the orientation direction of the glass fibers GF contained in the resin material 70R is aligned in the MD direction, which is the direction along the flow of the resin material 70R. Therefore, the resin material 70R not only has the anisotropy of the thermal expansion coefficients in the MD and TD directions, but also has anisotropy in the mechanical strength, specifically, the bending strength and bending modulus. That is, the bending strength and bending modulus in the MD direction are relatively large, and the bending strength and bending modulus in the TD direction are relatively small.

[0041] Incidentally, since the resin member 70 is formed by injection molding molten resin material 70R, the orientation direction of the glass fibers GF contained in the resin member 70 is aligned with the direction of flow of the resin material 70R during injection molding. Therefore, if the flow of the molten resin material 70R is not disturbed during injection molding and is allowed to flow in roughly one direction (for example, the battery width direction BH), the orientation direction of the glass fibers GF contained in the resin member 70 will tend to be aligned throughout the entire resin member 70, causing anisotropy in the bending strength and bending elasticity as well as thermal expansion of the resin member 70. This may result in the formation of portions in the resin member 70 with low bending strength.

[0042] Therefore, the orientation of the glass fibers GF in each portion of the resin member 70 in the battery 1 of this embodiment was investigated using an X-ray micro-CT (not shown). Specifically, the lid assembly 15 (see FIG. 14) was first manufactured, and then the lid member 30 and the terminal member 50 were dissolved and removed from the lid assembly 15, and only the molded resin member 70 was extracted. An X-ray micro-CT (in this embodiment, a TDM3000H-FP manufactured by Yamato Chemical Co., Ltd.) was used to perform tomography of the resin member 70, reconstructing a three-dimensional image of the resin member 70. The resin member 70 was then virtually divided into a number of rectangular parallelepiped three-dimensional meshes SM along three mutually orthogonal division planes, i.e., a division plane PPx orthogonal to the X-axis, a division plane PPy orthogonal to the Y-axis, and a division plane PPz orthogonal to the Z-axis (see FIG. 4).

[0043] In this embodiment, when imaging with the X-ray micro CT, the X axis of the device was aligned with the battery thickness direction CH of the resin member 70, the Y axis of the device was aligned with the battery height direction AH of the resin member 70, and the Z axis of the device was aligned with the battery width direction BH of the resin member 70, and tomographic imaging of the resin member 70 was performed. In this embodiment, the resin member 70 was virtually divided into 15 parts along the X axis (battery thickness direction CH), 11 parts along the Y axis (battery height direction AH), and 31 parts along the Z axis (battery width direction BH). In this embodiment, one three-dimensional mesh SM is a rectangular parallelepiped with each of orthogonal sides measuring approximately 800 μm.

[0044] Furthermore, using software provided with the X-ray micro-CT scanner, the average orientation direction MDR of the glass fibers GF contained in each of the three-dimensional meshes SM constituting the resin member 70 was obtained. Fig. 4 is a CC cross-sectional view of the resin member 70 according to this embodiment, showing the average orientation direction MDR obtained for each of the three-dimensional meshes SM projected onto each of the rectangular three-dimensional meshes SM that appear in the cross-section. In the CC cross-section (cross-section along the XY plane Pxy) of the resin member 70 shown in Fig. 4, it can be seen that the average orientation direction MDR (of which the XY direction component Mxy, described later) of each of the three-dimensional meshes SM faces in various directions.

[0045] Specifically, the average orientation direction MDR of the three-dimensional mesh SM that constitutes the resin member 70 at the surface portions that come into contact with each member, such as the cover member 30, the terminal member 50, and the mold (not shown in FIG. 4), is generally parallel to the surface of each member, such as the cover member 30. In the vicinity of the surface of each member, the molten resin material 70R often flows along the surface of each member. This is thought to be because the orientation direction of the glass fiber GF is aligned in a direction along the surface of each member.

[0046] On the other hand, the average orientation direction MDR of the three-dimensional mesh SM forming the resin member 70 in the inner portion away from the surface of each component varies depending on the location. In each three-dimensional mesh SM shown in Fig. 4, if the lines indicating the average orientation direction MDR are traced in order, spiral shapes or regions where the lines of the average orientation direction MDR are arranged radially are observed. In the resin member 70 of this embodiment, the injected molten resin material 70R progresses in a complex manner, such as by spiraling around in the inner portion away from each component, which is thought to result in the orientation direction of the glass fiber GF contained in the resin material 70R varying from region to region and becoming uneven overall.

[0047] As a reference form, as shown in FIG. 5, a test piece SP was also prepared, which was formed in a rectangular parallelepiped shape (width 10.7 mm, height 5.2 mm, depth 25.9 mm) that was long in the depth direction (direction along the Z-axis AZ described below) and with the orientation direction of the glass fiber GF aligned in the height direction (direction along the Z-axis AZ described below; from the lower left to the upper right in FIG. 5). This test piece SP was a test piece cut into a rectangular parallelepiped shape from a resin plate that had been cooled by forcing molten resin material 70R to flow in one direction. Therefore, in this test piece SP, the glass fiber GF was arranged in every position so that it extended in the height direction, and the glass fiber GF was oriented in the height direction.

[0048] As with the resin member 70 of the embodiment, tomography was performed using an X-ray micro-CT on this reference form test piece SP, and the average orientation direction MDR of the glass fibers GF contained within each three-dimensional mesh SM (not shown in Figure 5) that makes up the test piece SP was obtained.

[0049] When imaging the test specimen SP of the reference form using the X-ray micro-CT, the X axis of the device was aligned with the width direction of the test specimen SP, the Y axis of the device was aligned with the height direction of the test specimen SP, and the Z axis of the device was aligned with the depth direction of the test specimen SP, and tomography of the test specimen SP was performed. Using the tomography data of the test specimen SP for the reference form as well, the test specimen SP was divided into 28 parts along the X axis (width direction), 14 parts along the Y axis (height direction), and 65 parts along the Z axis (depth direction). In the reference form, each three-dimensional mesh SM is a rectangular parallelepiped with orthogonal sides measuring approximately 400 μm each.

[0050] The following describes how to represent the average orientation direction MDR of the glass fibers GF contained in each of the three-dimensional meshes SM of the resin member 70 of the embodiment and the test piece SP of the reference embodiment. As shown in Fig. 6, in an XYZ orthogonal coordinate system using the X-axis AX, Y-axis AY, and Z-axis AZ, which are orthogonal to each other, the average orientation direction MDR (shown by a thick solid line) is represented by the deflection angles θxy, θyz, and θzx of the three directional components Mxy, Myz, and Mzx of the average orientation direction MDR, which originates from the origin O. Of these, the deflection angle θxy is the angle between the X-axis AX and the XY-direction component Mxy (shown by a thick dashed line) of the average orientation direction MDR projected onto the XY-plane Pxy. Furthermore, the deflection angle θyz is the angle between the Y-axis AY and the YZ-direction component Myz (shown by a thick dashed line) of the average orientation direction MDR projected onto the YZ-plane Pyz. Furthermore, the deflection angle θzx is the angle between the Z-axis AZ and the ZX-direction component Mzx (shown by the thick dashed line) of the average alignment direction MDR projected onto the ZX plane Pzx. Each of the deflection angles θxy, θyz, and θzx can take a value in the range of -90 to +90 degrees. Needless to say, the XY plane Pxy, the YZ plane Pyz, and the ZX plane Pzx are perpendicular to one another.

[0051] Using the deflection angles θxy, θyz, θzx of the numerous average orientation directions MDR obtained for each of the numerous three-dimensional meshes SM constituting the resin member 70 of this embodiment, a graph of their frequency distribution was created, and the average values ​​AVxy, AVyz, AVzx and standard deviations σxy, σyz, σzx of the deflection angles θxy, θyz, θzx were calculated (see Figures 7 to 9).

[0052] Among the argument angles, we will first consider the power distribution of the argument θzx (see Figure 9). Theoretically, the value of the argument θzx can range from -90 degrees to +90 degrees. However, in the graph of the power distribution of the argument θzx shown in Figure 9, the power is high in the central part between -10 and +10 degrees, while the power is low in the other ranges (-90 to -10 degrees and +10 to +90 degrees). As a result, the average value AVzx of the argument θzx was -3.0 degrees, and the standard deviation σzx was 32.7 degrees. The value of the standard deviation σzx was relatively small compared to the standard deviation σxy of the argument θxy and the standard deviation σyz of the argument θyz, which will be described later.

[0053] 9 shows that most of the ZX-direction component Mzx of the average orientation direction MDR projected onto the ZX plane Pzx is parallel to the Z axis AZ. That is, when the average orientation direction MDR is projected onto a cross section (ZX plane Pzx) perpendicular to the battery height direction AH (Y axis AY), the ZX-direction component Mzx of the average orientation direction MDR is generally oriented in the battery width direction BH (direction along the Z axis AZ), indicating that the orientation of the glass fiber GF is generally aligned in the battery width direction BH (almost parallel to the Z axis AZ).

[0054] However, this is more than 10 times larger than the standard deviation σzx of the deflection angle θzx of the test piece SP described later, and as can be seen from FIG. 9, even though the degree is small, there are a certain number of degrees when the deflection angle θzx is in other ranges (-90 to -10 degrees and +10 to +90 degrees), which indicates that there are glass fibers GF whose orientation is not parallel to the Z-axis AZ.

[0055] 1 and 3, the resin member 70 has a shape that extends in the battery width direction BH, and also has many surfaces that extend in the battery width direction BH. Therefore, after the molten resin material 70R is injected into the gate portion 76, it generally flows toward the outer side BHO and inner side BHI in the battery width direction BH, i.e., in a direction along the Z-axis AZ, as viewed overall. For this reason, it is believed that the orientation of the glass fibers GF is generally aligned in the battery width direction BH (direction along the Z-axis AZ), and the frequency of the three-dimensional mesh SM in which the deflection angle θzx of the average orientation direction MDR is −10 to +10 degrees (approximately parallel to the Z-axis AZ) is higher than the other meshes.

[0056] Next, we will consider the power distribution of the deflection angle θyz (see Figure 8). Theoretically, the value of the deflection angle θyz can also range from -90 degrees to +90 degrees. However, the graph of the power distribution of the deflection angle θyz shown in Figure 8 has a different pattern from the distribution of the deflection angle θzx (Figure 9). The power distribution is roughly U-shaped, with the powers in the inner area between -80 and +80 degrees being small, while the powers between -80 and -90 degrees and +80 and +90 degrees are very large. As a result, the average value AVyz was 8.9 degrees and the standard deviation σyz was a large value of 73.3 degrees.

[0057] 8 shows that most of the YZ-direction component Myz of the average orientation direction MDR projected onto the YZ plane Pyz is oriented nearly perpendicular to the Y-axis AY, that is, generally parallel to the Z-axis AZ. That is, when the average orientation direction MDR is projected onto a cross section (YZ plane Pyz) perpendicular to the battery thickness direction CH (X-axis AX), the YZ-direction component Myz of the average orientation direction MDR also points generally in the battery width direction BH (direction along the Z-axis AZ), which also shows that the orientation of the glass fiber GF is generally aligned in the battery width direction BH (approximately parallel to the Z-axis AZ).

[0058] As described above, the resin member 70 has a shape that extends in the battery width direction BH, and also has many surfaces that extend in the battery width direction BH, and the molten resin material 70R flows generally toward the outer side BHO and inner side BHI in the battery width direction BH, i.e., in the direction along the Z-axis AZ, after being injected into the gate portion 76. For this reason, it is considered that the orientation of the glass fibers GF is generally aligned in the battery width direction BH (direction along the Z-axis AZ), and the frequency of the three-dimensional mesh SM in which the deflection angle θyz of the average orientation direction MDR is −80 to −90 degrees and +80 to +90 degrees (almost parallel to the Z-axis AZ), similar to the deflection angle θzx described above, is higher than the other meshes.

[0059] However, as can be seen from Figure 8, even though the degree is small, there is a certain degree when the deflection angle θyz is between -80 and +80 degrees, and therefore, even when viewed in the YZ plane Pyz, there are glass fibers GF whose orientation is not parallel to the Z axis AZ.

[0060] Finally, let's consider the power distribution of the deflection angle θxy. Theoretically, the value of the deflection angle θxy can range from -90° to +90°. However, unlike the power distributions of the deflection angles θzx and θyz described above, the graph of the power distribution of the deflection angle θxy shown in Figure 7 shows that the power is higher in the central area between -10 and +10° than in the other areas. In addition, in the ranges of -30 to -90° and +40 to +90°, the power gradually increases toward the outer edges toward -80 to -90° and +80 to +90°, forming a roughly W-shaped power distribution. However, in the graph of Figure 7, there is no angle range with extremely low power, and all angle ranges have powers above 147. The average value AVxy of this distribution was 2.1°, and the standard deviation σxy was 53.3°.

[0061] 7 shows that many glass fibers GF are oriented generally parallel to the X-axis AX or the Y-axis. On the other hand, the graph shows that the deflection angle θxy formed between the X-axis AX and the X-axis component Mxy, which is obtained by projecting the average orientation direction MDR onto the XY plane Pxy, varies throughout the entire resin member 70. That is, as can be seen from the fact that the average orientation direction MDR is spirally or radially shaped in the cross section of the resin member 70 taken along the XY plane Pxy shown in FIG. 4, when the X-axis component Mxy, which is obtained by projecting the average orientation direction MDR onto a cross section (XY plane Pxy) perpendicular to the battery width direction BH (Z-axis AZ), is viewed, the X-axis component Mxy faces in various directions, indicating that the orientation is irregular.

[0062] To summarize the above, in the resin member 70 of this embodiment, considering the deflection angles θzx and θyz described above, most of the resin member 70 is oriented in a direction generally parallel to the Z-axis AZ. On the other hand, considering the deflection angle θxy, the XY-direction component Mxy of the average orientation direction MDR projected onto a cross section (XY plane Pxy) perpendicular to the battery width direction BH (Z-axis AZ) faces in various directions. In other words, unlike the test specimen SP described below, the orientation of the glass fibers GS is irregular throughout the resin member 70. For this reason, the battery 1 uses a resin member 70 in which the standard deviations σxy, σyz, and σzx of the frequency distribution of any of the deflection angles θxy, θyz, and θzx associated with the average orientation direction MDR are all 5 degrees or greater. Therefore, compared to using a resin member in which any one of the standard deviations σxy, σyz, and σzx is less than 5 degrees, a resin member 70 is used in which the anisotropy of the resin material 70R is suppressed, resulting in a battery 1 with improved reliability. Furthermore, the battery 1 uses a resin member 70 in which all of the standard deviations σxy, σyz, and σzx are 18 degrees or greater. Therefore, compared to a case in which a resin member in which any of the standard deviations σxy, σyz, and σzx is less than 18 degrees is used, the resin member 70 uses resin material 70R with reduced anisotropy, resulting in a battery 1 with even higher reliability.

[0063] On the other hand, for the reference form test specimen SP, a frequency distribution was created using the deflection angles θxy, θyz, θzx of the numerous average orientation directions MDR obtained for each of the numerous three-dimensional meshes SM that make up the test specimen SP, and the average values ​​AVxy, AVyz, AVzx and standard deviations σxy, σyz, σzx of the deflection angles θxy, θyz, θzx were calculated (see Figures 10 to 12).

[0064] For the test piece SP, we first examined the power distribution of the declination angle θzx among the various declination angles. As shown in Figure 12, the power distribution of the declination angle θzx is extremely high in the central area, and the declination angle θzx is limited to values ​​within a narrow range of roughly -10 to +10 degrees, forming a Gaussian distribution with a sharp peak in the central area. The average value AVzx was 0.0 degrees, and the standard deviation σzx was only 2.8 degrees.

[0065] The frequency distribution of the deflection angle θzx shown in Figure 12 indicates that most of the ZX-direction component Mzx, which is the projection of the average orientation direction MDR onto the ZX plane Pzx, is parallel to the Z axis AZ (depth direction) (see Figure 5). In other words, in most of the three-dimensional meshes SM that make up the specimen SP, the average orientation direction MDR is oriented along the Z axis (height direction), indicating that the orientation of the glass fiber GF is aligned approximately parallel to the Z axis AZ. Conversely, this also indicates that the orientation direction of the glass fiber GF can be appropriately identified by examining the frequency distribution of the deflection angle using X-ray micro-CT. Note that, unlike the other frequency distribution graphs (Figures 7 to 11), only Figure 12 has a narrower angle range on the horizontal axis.

[0066] Next, we will consider the power distribution of the deflection angle θyz. In the graph of the power distribution of the deflection angle θyz shown in Figure 11, the power distribution is approximately U-shaped, with the power in the angular range of -80 to +80 degrees being 0, while the power in the range of -80 to -90 degrees and +80 to +90 degrees is very large. Therefore, the average value AVzx of the deflection angle θyz was -28.1 degrees, and the standard deviation σzx was an extremely large value of 83.9 degrees. The power distribution of the deflection angle θyz shown in Figure 11 indicates that most of the YZ-direction component Myz, which is the projection of the average orientation direction MDR onto the YZ plane Pyz, is oriented perpendicular to the Y-axis AY, that is, parallel to the Z-axis AZ.

[0067] Considering these deflection angles θzx and θyz together, it can be seen that in most of the three-dimensional meshes SM that make up the test specimen SP, the average orientation direction MDR is aligned in the direction along the Z axis AZ (depth direction). In other words, it can be seen that in the test specimen SP, the glass fibers GS are aligned in the direction almost along the Z axis AZ (depth direction).

[0068] Finally, we will consider the power distribution of the deflection angle θxy. In the graph of the power distribution of the deflection angle θxy shown in Figure 10, the power in the central part, i.e., the angle range of -10 to +10 degrees, is about twice as high as the other angle ranges. On the other hand, the power is roughly the same in the other angle ranges (-90 to -10 degrees, 10 to 90 degrees). The average value AVxy was 1.7 degrees, and the standard deviation σxy was 47.5 degrees.

[0069] The frequency distribution of the deflection angle θxy shown in Fig. 10 indicates that, among the numerous three-dimensional meshes SM constituting the test specimen SP, there are a relatively large number of three-dimensional meshes SM in which the XY direction component Mxy, obtained by projecting the average orientation direction MDR onto the XY plane Pxy, is oriented in the direction along the X axis AX (width direction). On the other hand, there are also a considerable number of three-dimensional meshes SM in which the XY direction component Mxy is oriented in various directions within the XY plane Pxy.

[0070] However, as mentioned above, it is known that the average orientation direction MDR of most of the three-dimensional meshes SM constituting the test specimen SP is aligned along the Z-axis AZ from the frequency distributions of the deflection angles θzx and θyz in Figures 11 and 12. Taking this into consideration, it can be understood that the average orientation direction MDR of most of the three-dimensional meshes SM constituting the test specimen SP is oriented along the Z-axis AZ, but is not completely parallel to the Z-axis AZ and is slightly tilted, and this tilt occurs in both the X-axis AX and the Y-axis AY, but there is a tendency for the glass fibers GS to be slightly more inclined in the direction along the X-axis AX (width direction).

[0071] Furthermore, from the results of the test piece SP shown in Figures 10 to 12, it can be seen that when the orientation of the glass fibers GS is uniform, any one of the standard deviations σxy, σyz, σzx of the three deflection angles θxy, θyz, θzx becomes a small value less than 5 degrees.

[0072] Next, a method for manufacturing the battery 1 of this embodiment will be described (see FIGS. 13 to 15). First, a pre-roughening lid member 30 is prepared. The pre-roughening lid member 30 is obtained by pressing an aluminum plate. Also, a pre-roughening terminal member 50 is prepared. The pre-roughening terminal member 50 is obtained by pressing a metal plate (an aluminum plate for the positive electrode and a copper plate for the negative electrode).

[0073] Then, in the terminal roughening step S1, pulsed laser light is intermittently irradiated onto the bent extending portion 50b of the terminal member 50 while shifting the irradiation position, to form a belt-shaped, annular first roughened portion 51 (see FIG. 3).

[0074] Separately, in a lid roughening process S2, pulsed laser light is intermittently irradiated onto the outer surface 30s1 and the inner surface 30s2 of the peripheral edge 31 of the terminal insertion hole 30h of the lid member 30 while shifting the irradiation position, to form a band-shaped, annular lid seal outer roughened portion 31s1 and a band-shaped, annular lid seal inner roughened portion 31s2, respectively (see FIG. 3). The irradiation conditions for the pulsed laser light were the same as those for irradiating the positive electrode terminal member 50 with a laser in the terminal roughening process S1.

[0075] Next, in the insert molding process S3, a lid assembly 15 is formed by insert molding, in which the lid member 30 and the pair of terminal members 50 are fixed together with the resin member 70 (see the upper part of FIG. 14). Specifically, in the part setting process S31, the lid member 30 and the positive and negative terminal members 50 are fixed in a closed mold DI, which is made up of an upper mold DU, a lower mold DD, etc., with the positive and negative terminal members 50 inserted into the pair of terminal insertion holes 30h of the lid member 30, and a cavity CV is formed. Note that in FIG. 15, the lower mold DD, which is movable in the vertical direction, includes a slide mold DS which moves between an advanced position where it presses the bent portion 50db provided in the connecting portion 50d of the terminal member 50, and a retracted position (shown by a dashed line) where the terminal members 50 can be inserted and removed.

[0076] In the resin injection process S32, molten resin material 70R is injected into the cavity CV and welded to the peripheral edge 31 of the lid member 30 and to a portion of the top plate portion 50a, bent extension portion 50b, and stepped extension portion 50c of the terminal member 50. At this time, the molten resin material 70R also fills the roughened portions of the lid member 30, forming the outer lid seal roughened portion 31s1 and the inner lid seal roughened portion 31s2, and firmly bonds them. In this resin injection process S32, the resin material 70R injected into the cavity CV advances from the gate portion 76 toward each portion of the resin member 70. At this time, the molten resin material 70R advances in a complex manner, such as by spiraling around, resulting in the orientation direction of the glass fibers GF contained in the resin material 70R varying from portion to portion, resulting in an overall irregularity.

[0077] In the pressure holding and cooling step S33, the resin material 70R is cooled while maintaining the pressure. In the demolding step S34, the slide mold DS is retracted and the lower mold DD is lowered to demold the resin members 70, and the lid assembly 15 having the pair of resin members 70 is removed from the mold DI.

[0078] Next, in the electrode body connecting process S4, the connection portion 50d of the positive electrode terminal member 50P of the lid assembly 15 is welded to the positive electrode current collecting portion 40p of the electrode body 40 prepared in advance (see FIGS. 1, 2, and 14). Also, the connection portion 50d of the negative electrode terminal member 50N is welded to the negative electrode current collecting portion 40n of the electrode body 40. Thereafter, the electrode body 40 is wrapped in a bag-shaped insulating holder 7.

[0079] Next, in the electrode assembly containing / case forming process S5, the electrode assembly 40 covered with the insulating holder 7 described above is inserted into the case body member 20, and the opening 20c of the case body member 20 is closed with the lid member 30. Furthermore, the opening 20c of the case body member 20 and the peripheral edge portion 30f of the lid member 30 are laser-welded airtightly around the entire periphery to form the case 10 containing the electrode assembly 40 inside.

[0080] Next, in a liquid filling and sealing step S6, electrolyte 5 is poured into case 10 through liquid filling hole 30k, and electrolyte 5 is impregnated into electrode body 40. Thereafter, liquid filling hole 30k is covered from the outside with liquid filling plug 12, and liquid filling plug 12 is laser-welded to case 10 airtightly. Next, in the initial charging and aging step S7, a charging device (not shown) is connected to the battery 1 to perform an initial charge on the battery 1. After that, the initially charged battery 1 is left standing at a high temperature (e.g., 60°C) for a predetermined time to age the battery 1. In this way, the battery 1 is completed.

[0081] Although the present invention has been described above in accordance with the embodiments, it goes without saying that the present invention is not limited to the embodiments and can be modified and applied as appropriate within the scope of the invention. [Explanation of symbols]

[0082] 1. Battery (energy storage device) 10 cases 20 Case body member (case member) 30 Lid member (case member) 30h Terminal insertion hole 40 Electrode body 50 Terminal member 50P positive terminal material 50N negative terminal material 70 Resin components 70R resin material PPx,PPy,PPz splitting planes SM three-dimensional メッシュ MDR average alignment direction Mxy XY direction component Myz YZ direction component Mzx ZX directional component Pxy XY plane Pyz YZ plane Pzx ZX plane θxy,θyz,θzx declination angle AVxy,AVyz,AVzx (deviation angle) average value σxy,σyz,σzx (angle) standard deviation AX X-axis AY Y-axis AZ Z axis

Claims

1. a case member having a terminal insertion hole; A terminal member inserted into the terminal insertion hole; and a resin member made of an insulating resin material and airtightly welded to the case member and the terminal member, respectively, to fix the terminal member to the case member while insulating it from the case member; An electricity storage device, the resin material forming the resin member contains glass fiber; The resin member is taking a tomographic image of the resin member using an X-ray micro CT; When the average orientation direction of the glass fibers is obtained for each rectangular solid mesh included in the resin member, and the deviation angles of three directional components obtained by projecting this average orientation direction onto three planes orthogonal to each other are obtained, The standard deviations of the frequency distributions of the three deviation angles obtained for all the three-dimensional meshes included in the resin member are all 5 degrees or more. Energy storage device.

2. The electricity storage device according to claim 1 , The standard deviation of the frequency distribution of the three deviation angles is 18 degrees or more. Energy storage device.

3. The electricity storage device according to claim 1 or 2, the case member is made of aluminum, the terminal member is a positive electrode terminal member made of aluminum, The resin material constituting the resin member has an MD / TD average thermal expansion coefficient of 1.8 to 3.0 × 10 -5 (1 / K) Energy storage device.

4. The electricity storage device according to claim 1 or 2, the case member is made of aluminum, the terminal member is a negative electrode terminal member made of copper, The resin material constituting the resin member has an MD / TD average thermal expansion coefficient of 1.7 to 2.5 × 10 -5 (1 / K) Energy storage device.

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