Power storage device

Abstract

To provide a power storage device that has an insulating resin member formed integrally with a case member and a terminal member by insert molding, while having improved reliability in terms of airtightness.SOLUTION: A power storage device 1 includes a case member 30 having a terminal insertion hole 30h, a terminal member 50 inserted into the terminal insertion hole, and a resin member 70 made of an insulating resin material 70R and hermetically welded to each of the case member and the terminal member to fix the terminal member to the case member while insulating it from the case member. The terminal member includes a ring-shaped, band-shaped first roughened portion 51 that is roughened and surrounds the terminal member, and second roughened portions 52a, 52b that are spaced from the first roughened portion and are roughened. The resin member is insert-molded integrally with the case member and the terminal member, and includes a ring-shaped, band-shaped terminal seal portion 74 that is hermetically fixed to the first roughened portion, and a stress reduction portion 75 that is fixed to the second roughened portion and reduces stress generated in the terminal seal portion.SELECTED DRAWING: Figure 1

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 lid, one of the case members of an electricity storage device, inserting a terminal member into this terminal insertion hole, and integrally and airtightly fixing the lid and the terminal member to each other using an insulating resin member by insert molding (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-44303 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, due to differences in the thermal expansion coefficients of the case member (lid), terminal member, and resin member, stress occurs due to the difference in thermal expansion when the temperature is lowered in the insert molding process. After molding or when cooling in a thermal cycle test, the stress can cause cracks in the resin member along the terminal member, compromising the airtightness of the case and reducing reliability in terms of airtightness.

[0005] The present invention has been made in consideration of the above-mentioned current situation, and provides an electricity storage device that has an insulating resin member that is integrally formed with a case member and terminal members by insert molding, yet has improved reliability in terms of airtightness. [Means for solving the problem]

[0006] (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, a terminal member 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 member to the case member while insulating it from the case member, wherein the terminal member has a ring-shaped, band-shaped first roughened portion that is roughened and surrounds the terminal member, and a second roughened portion that is spaced from the first roughened portion and is roughened, the resin member is insert molded integrally with the case member and the terminal member inserted into the terminal insertion hole, and the electricity storage device has a ring-shaped, band-shaped terminal seal portion that is hermetically fixed to the first roughened portion of the terminal member, and a stress reduction portion that is fixed to the second roughened portion of the terminal member to reduce stress generated in the terminal seal portion.

[0007] In this electricity storage device, stress remains in the resin member due to the temperature drop after insert molding. However, in this electricity storage device, the terminal seal portion of the resin member is fixed to the first roughened portion of the terminal member to maintain airtightness between the first roughened portion and the terminal seal portion, and the stress reduction portion of the resin member is fixed to the second roughened portion of the terminal member to reduce the stress generated in the terminal seal portion of the resin member. Therefore, in this electricity storage device, the stress generated in the terminal seal portion can be reduced compared to when the terminal member does not have the second roughened portion or when the resin member does not have the stress reduction portion. Therefore, it is possible to suppress the occurrence of a defect in which cracks occur in the terminal seal portion and the airtightness of the terminal seal portion is reduced, and it is possible to provide an electricity storage device with improved reliability in terms of airtightness.

[0008] An example of a case where the resin member does not have a stress reducing portion is a case where the resin member does not have a portion corresponding to the stress reducing portion, regardless of the presence or absence of the second roughened portion in the terminal member. Also, an example of a case where the terminal member does not have a second roughened portion is a case where the resin member has a portion corresponding to the stress reducing portion, but the terminal member does not have a roughened surface corresponding to the second roughened portion, so that the portion of the resin member corresponding to the stress reducing portion cannot be fixed to the portion of the terminal member corresponding to the second phase portion.

[0009] 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 second metal forming the terminal member may be the same as the first metal forming the case member (for example, both are aluminum) or different (for example, aluminum and copper).

[0010] The stress reduction portion of the resin member is fixed to the second roughened portion of the terminal member, and may include cracks due to cohesive failure along the second roughened portion while maintaining its adhesion to the second roughened portion, or may have no cracks. In addition, the second roughened portion of the terminal member may be formed in a range where the stress reducing portion of the resin member can be fixed to reduce the stress generated in the terminal seal portion of the resin member, and may be annular and strip-shaped surrounding the terminal member or may not be annular and strip-shaped. The stress reducing portion may also be annular and strip-shaped fixed to the second roughened portion, but may not be annular and strip-shaped.

[0011] (2) In the energy storage device described in (1) above, it is preferable that the stress reduction portion is fixed to the second roughened portion of the terminal member and is a crack-containing portion that includes a crack due to cohesive failure along the second roughened portion.

[0012] In this electricity storage device, the stress reducing portion is a crack containing portion that includes a crack. That is, it is considered that the stress generated in the stress reducing portion exceeded the strength of the resin material, and thus a crack was generated in the stress reducing portion due to cohesive failure. However, the occurrence of this crack releases the stress generated in the stress reducing portion, which in turn reduces the stress generated in the terminal seal portion, resulting in a more stable state.

[0013] (3) In the energy storage device described in (1) or (2) above, the first roughened portion of the terminal member may be configured as a forest of nanopillars having a height of 50 nm or more, each of which is formed by particles originating from the terminal member being linked together in a string-like pattern, and the terminal seal portion of the resin member may be configured as a forest of nanopillars hermetically fixed to the first roughened portion by filling the spaces between the nanopillars with the resin material.

[0014] In this electricity storage device, the first roughened portion of the terminal member is a roughened surface with a forest of nano-pillars, while the resin material constituting the terminal seal portion of the resin member is filled between the nano-pillars, so that the first roughened portion and the terminal seal portion can be firmly fixed to each other and good airtightness can be maintained between them.

[0015] (4) In the electricity storage device described in any one of (1) to (3) above, it is preferable that the second roughened portion of the terminal member is a forest of nanopillars with a height of 50 nm or more, in which particles derived from the terminal member are linked together in a string-like manner to form a columnar shape, and the stress reduction portion of the resin member is a forest of the nanopillars with the resin material filled between the nanopillars and fixed to the second roughened portion.

[0016] In this electricity storage device, the second roughened portion of the terminal member is a roughened surface with a forest of nano-pillars, while the resin material constituting the stress reducing portion of the resin member is filled between the nano-pillars, so that the second roughened portion and the stress reducing portion are firmly fixed to each other. [Brief description of the drawings]

[0017] [Figure 1] 1 is a perspective view of a battery according to an embodiment, a comparative example, and a modified example. FIG. [Diagram 2] 1A to 1C are longitudinal cross-sectional views taken along the battery height direction and the battery width direction of a battery according to an embodiment, a comparative embodiment, and a modified embodiment. [Diagram 3] 3 is a partially enlarged cross-sectional view showing an enlarged area near a terminal insertion hole of a lid member of the battery according to the embodiment. FIG. [Figure 4]1A to 1C are partially enlarged cross-sectional views showing nano-pillars standing in a forest in the roughened portion of the terminal member and the cover member and the filled resin member in the embodiment, comparative embodiment, and modified embodiment. [Diagram 5] 2 is a flowchart of a method for manufacturing a battery according to an embodiment. [Figure 6] FIG. 2 is an exploded view of a battery according to an embodiment, a comparative example, and a modified example. [Figure 7] 11 is an explanatory diagram showing how a pulsed laser beam is scanned to form a plurality of cup-shaped recesses and nano-pillars standing in the cup-shaped recesses in a seal portion forming step in a manufacturing method for a battery according to an embodiment. FIG. [Figure 8] 13 is a partially enlarged cross-sectional view showing the vicinity of a terminal insertion hole of a lid member, a terminal member, and a resin member in a modified embodiment of the battery; FIG. [Figure 9] 9 is a cross-sectional view taken along the line DD in FIG. 8 of a modified embodiment of the battery. [Figure 10] FIG. 13 is a partially enlarged cross-sectional view showing the vicinity of a terminal insertion hole of a lid member, a terminal member, and a resin member in a battery according to a comparative embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] (Embodiment) Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 shows a perspective view of a battery (electricity storage device) 1 according to this embodiment, and Fig. 2 shows a vertical cross-sectional view of the battery 1. Fig. 3 shows a partially enlarged cross-sectional view of the vicinity of the terminal insertion hole 30h of the cover member 30 of the cover 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.

[0019] This battery 1 is a square (rectangular) sealed lithium ion secondary battery that is mounted on vehicles such as hybrid cars, plug-in hybrid cars, and electric cars. The battery 1 is composed of a case 10, an electrode body 40 housed in the case 10, and positive and negative terminal members 50 fixed to the case 10 via resin members 70. The electrode body 40 is covered in a bag-shaped insulating holder 7 made of an insulating film within the case 10. An electrolyte 5 is also housed within the case 10, a part of which is impregnated in the electrode body 40 and the remainder is stored at the inside bottom of the case 10.

[0020] The case 10 is a rectangular box made of metal (aluminum in this embodiment), and is configured of a case body member 20 having a rectangular opening 20c and a rectangular plate-like lid member 30 that houses an electrode body 40 therein, and a rectangular plate-like lid member 30 that closes the opening 20c of the case body member 20. The opening 20c of the case body member 20 and the peripheral portion 30f of the lid member 30 are hermetically welded all around. The lid member 30 is provided with a safety valve 11 that breaks 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 disk-like liquid inlet plug 12 made of aluminum.

[0021] The electrode body 40 is a flat cylindrical wound type, and is formed by alternately stacking and winding long strip-shaped positive electrode plates 41 and negative electrode plates 42 with two long strip-shaped porous resin separators 43, and then compressing them in the battery thickness direction CH to form a flat shape. A positive electrode current collector 40p is formed on one side BH1 (left side in FIG. 2) of the battery width direction BH along the winding axis 40X, in which the current collector foil of the positive electrode plate 41 is overlapped in a spiral shape. This positive electrode current collector 40p is welded to the positive electrode terminal member 50 and is electrically connected. In addition, a negative electrode current collector 40n is formed on the other side BH2 (right side in FIG. 2) of the electrode body 40 in the battery width direction BH, in which the current collector foil of the negative electrode plate 42 is overlapped in a spiral shape. This negative electrode current collector 40n is welded to the negative electrode terminal member 50 and is electrically connected.

[0022] 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 50 made of aluminum is inserted into the terminal insertion hole 30h on the one side BH1, and the terminal member 50 is airtightly fixed to the lid member 30 in a state insulated from the lid member 30 via a resin member 70 welded thereto. On the other hand, a negative electrode terminal member 50 made of copper is inserted into the terminal insertion hole 30h on the other side BH2, and the terminal member 50 is airtightly fixed to the lid member 30 in a state insulated from the lid member 30 via a resin member 70 welded thereto.

[0023] As can be easily understood from Figures 1 and 2, the positive and negative terminal members 50 have roughly mirror-image shapes, and are made by cutting and bending metal plates (aluminum plate for the positive electrode and copper plate for the negative electrode) using a press.

[0024] The terminal member 50 is located above the cover member 30 in the battery height direction AH, and has 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 bent at a right angle from the edge of one side CH1 of the top plate portion 50a in the battery thickness direction CH (the rear side in Figures 2 and 3) and extending 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 FIG. 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 connection portion 50d that extends from the stepped extension portion 50c to the lower side AH2 in the battery height direction AH, bends midway to the other side CH2 in the battery thickness direction CH (the front side in FIG. 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 connection portion 50d all have a rectangular shape whose cross section perpendicular to the battery height direction AH is long in the battery width direction BH.

[0025] 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 terminal member 50 is welded to the positive current collector 40p of the electrode body 40, so that the positive electrode potential of the positive current collector 40p is drawn to the top plate portion 50a of the positive terminal member 50. Similarly, the connection portion 50d of the negative terminal member 50 is welded to the negative current collector 40n of the electrode body 40, so that the negative electrode potential of the negative current collector 40n is drawn to the top plate portion 50a of the negative terminal member 50.

[0026] The positive and negative terminal members 50 are fixed integrally to the cover member 30 by the resin member 70 molded by insert molding. The resin member 70 in this embodiment is made of a resin material 70R including a thermoplastic main resin (specifically, polyphenylene sulfide (PPS)), a thermoplastic elastomer, and a filler (specifically, a fibrous glass filler). 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 which is a terminal seal portion, and a step surrounding portion 75 which is a stress reducing portion. Among these, the top plate peripheral portion 71 is a rectangular ring-shaped portion located outside the planar direction of the top plate portion 50a of the terminal member 50, that is, around the battery width direction BH and the battery thickness direction CH. The outer peripheral portion 72 is an annular portion located on the lower side AH2 of the top plate peripheral portion 71 and on the upper side AH1 of the annular peripheral portion 31 surrounding the terminal insertion hole 30h of the cover member 30. The inner peripheral portion 73 is an annular portion located on the lower side AH2 of the peripheral portion 31 of the cover member 30. The insertion hole filling portion 74 is an annular portion located on the lower side AH2 of the top plate peripheral portion 71 and sandwiched between the inner peripheral surface 30hs of the terminal insertion hole 30h of the cover member 30 and the bent extension portion 50b of the terminal member 50. The step surrounding portion 75 is an annular portion surrounding the step extension portion 50c of the terminal member 50 with the lower side AH2 of the insertion hole filling portion 74 and the lower side AH2 of the cover member 30.

[0027] First, the bonding and airtightness between the lid member 30 and the resin member 70 in the battery 1 will be described. An annular, band-shaped lid seal outer roughened portion 31s1 surrounding the terminal insertion hole 30h 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 a thick line in FIG. 3. An annular, band-shaped lid seal inner roughened portion 31s2 surrounding the terminal insertion hole 30h is formed on the inner surface 30s2 facing the lower side AH2 of the peripheral portion 31, as shown by a thick line in FIG. 3. The lid seal outer roughened portion 31s1 and the lid seal inner roughened portion 31s2 are roughened surfaces roughened by a roughening process using a pulsed laser beam LC, which will be described later. That is, as shown in FIG. 4, in the lid seal outer roughened portion 31s1 and the lid seal inner roughened portion 31s2, particles 36p derived from the metal constituting the lid member 30 (aluminum in this embodiment) are linked together in a string-like shape to form a large number of nanopillars 36 each having a height ha of 50 nm or more (in this embodiment, the height ha is approximately 150 nm).

[0028] In addition, the outer roughened portion 31s1 of the lid seal and the inner roughened portion 31s2 of the lid seal are filled with the resin material 70R forming the outer peripheral portion 72 and the inner peripheral portion 73 of the resin member 70. Therefore, the outer roughened portion 31s1 of the lid seal and the outer peripheral portion 72 of the lid seal, and the inner roughened portion 31s2 of the lid seal and the inner peripheral portion 73 of the lid seal are firmly fixed with a long creeping distance in the width direction (radial direction of the terminal insertion hole 30h) of the outer roughened portion 31s1 of the lid seal or the inner roughened portion 31s2 of the lid seal. Therefore, 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. In addition, in the battery 1 of this embodiment, two roughened portions, namely, the outer roughened portion 31s1 of the lid seal and the inner roughened portion 31s2 of the lid seal, are provided on the peripheral portion 31 of the lid member 30, so that particularly high reliability in terms of airtightness can be obtained between the lid member 30 and the resin member 70.

[0029] Next, the bonding and airtightness between the positive and negative terminal members 50 and the resin member 70 in the battery 1 will be described. In the positive and negative terminal members 50, as shown by the dotted pattern and thick line in FIG. 3, the bent extension portion 50b is located near the terminal insertion hole 30h and is a band-like annular portion surrounding the terminal member 50, which is a first roughened portion 51. The first roughened portion 51 is a rectangular annular band-like roughened surface consisting of four surfaces: an inner end surface roughened portion 51a facing the inner side BHI in the battery width direction BH, an outer end surface roughened portion 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. The first roughened portion 51 is also a roughened surface obtained by roughening treatment using pulsed laser light LC, which will be described later. That is, as shown in FIG. 4, in the first roughened portion 51, particles 56p derived from the metal constituting the terminal member 50 (in this embodiment, the positive terminal member is aluminum, and the negative terminal member is copper) are linked together in a string-like manner to form columnar nanopillars 56 with a height ha of 50 nm or more (in this embodiment, the height ha is approximately 150 nm).

[0030] 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).

[0031] As a result, 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.

[0032] Furthermore, in this embodiment, the end surface roughened portions 52a, 52b, which are second roughened portions, are formed in a part of the step extension portion 50c of the positive and negative terminal members 50. Specifically, as shown by the thick line in Fig. 3, the end surface roughened portion 52a facing the inner side BHI of the battery width direction BH and the end surface roughened portion 52b facing the outer side BHO of the battery width direction BH on the upper side AH1 of the step extension portion 50c in the battery height direction AH are also roughened by a roughening process using a pulsed laser light LC described later. That is, as shown in Fig. 4, the end surface roughened portions 52a, 52b also have nano-pillars 56 with a height ha of 50 nm or more (approximately a height ha = 150 nm) formed by particles 56p derived from the metal (aluminum or copper in this embodiment) constituting the terminal member 50, which are linked in a string-like manner.

[0033] As described later, the roughened end surfaces 52a, 52b of the stepped extension portion 50c are also filled with a resin material 70R constituting the resin member 70. Therefore, the step surrounding portion 75 of the resin member 70 surrounds the stepped extension portion 50c of the terminal member 50 and is firmly fixed to at least two of the roughened end surfaces 52a, 52b of the stepped extension portion 50c.

[0034] As described later, the resin material 70R is injection molded to integrally fix the cover member 30 and the pair of terminal members 50 inserted into the terminal insertion holes 30h with the resin material 70 to form the cover assembly 15. However, since there is a difference in thermal expansion coefficient between the metals (aluminum and copper in this embodiment) constituting the cover member 30 and the terminal members 50 and the resin material 70R, thermal stress occurs in each member that is cooled after molding due to the difference in thermal expansion.

[0035] Here, as shown in FIG. 10 , a comparative battery C1 is the same as the battery 1 of this embodiment, but differs only in that the stepped extension portion 50c of the terminal member 50 does not have the roughened end surface portions 52a, 52b, and the battery 1 of this embodiment is compared to explain the stresses that occur in each portion of the resin member 70.

[0036] In the comparative battery C1, when the battery C1 is exposed to a temperature environment of about room temperature, or when the battery C1 is exposed to an environment lower than room temperature (for example, −40° C.) in a thermal cycle test or the like, a relatively high stress is generated in the resin member 70 near the first roughened portion 51 of the insertion hole filling portion 74. In particular, a high stress is generated in the insertion hole filling portion 74 near the outer end surface roughened portion 51b of the first roughened portion 51. In addition, a higher stress is generated in the insertion hole filling portion 74 near the inner end surface roughened portion 51a than in the outer end surface roughened portion 51b, and therefore the highest stress is generated in the resin member 70.

[0037] Therefore, when the battery C1 is exposed to an environment at room temperature or lower, as shown in FIG. 10, a crack CL1 due to cohesive failure may occur along the rough inner end surface 51a of the insertion hole filling portion 74 of the resin member 70 near the rough inner end surface 51a. In addition, a crack (not shown) due to cohesive failure may also occur near the rough outer end surface 51b. This is considered to be because the stress generated in these areas exceeds the strength of the resin material 70R. In the battery C1 in which the crack CL1 occurs in the insertion hole filling portion 74 of the resin member 70, the airtightness of the interface between the terminal member 50 and the resin member 70 is greatly reduced. Thus, it is found that the battery C1 of the comparative embodiment has low reliability in terms of airtightness, regardless of whether or not the crack CL1 occurs.

[0038] In contrast, when the battery 1 of this embodiment is exposed to an environment at approximately room temperature or even lower, the stress generated in the insertion hole filling portion 74 of the resin member 70 near the outer end surface roughened portion 51b and the inner end surface roughened portion 51a of the first roughened portion 51 is significantly lower (for example, approximately 1 / 2 or less in this embodiment) than that of battery C1.

[0039] However, instead, in the resin member 70, a stress higher than the stress near the outer end surface roughened portion 51b of the first roughened portion 51 is generated near the end surface roughened portion 52b of the outer BHO of the step surrounding portion 75. In addition, a stress higher than the stress near the inner end surface roughened portion 51a of the first roughened portion 51 is generated near the end surface roughened portion 52a of the inner BHI, and the highest stress in the resin member 70 is generated.

[0040] In the battery 1 of this embodiment, as described above, the terminal member 50 is provided with not only the first roughened portion 51 fixed to the insertion hole filling portion 74, but also the roughened end portions 52a, 52b fixed to the step surrounding portion 75 located outside (lower side AH2 in this embodiment) as viewed from the insertion hole filling portion 74 and having a relatively large volume. Therefore, most of the stress generated in the resin member 70 due to the thermal expansion difference generated with cooling of the battery 1 is applied to the portion of the step surrounding portion 75 near the roughened end portions 52a, 52b. Accordingly, it is considered that the stress generated in the insertion hole filling portion 74 near the outer end surface roughened portion 51b and the inner end surface roughened portion 51a of the first roughened portion 51 is reduced compared to the battery C1.

[0041] That is, in this embodiment, a portion of the step surrounding portion 75 of the resin member 70 is fixed to the end surface roughened portions 52a, 52b of the terminal member 50, thereby reducing the stress generated in the insertion hole filling portion 74, particularly in the vicinity of the outer end surface roughened portion 51b and the inner end surface roughened portion 51a. As a result, in the battery 1 of this embodiment, unlike the battery C1, the occurrence of cracks CL1 (see Figure 10) is prevented in the insertion hole filling portion 74 of the resin member 70 near the inner end surface roughened portion 51a or near the inner end surface roughened portion 51a and the outer end surface roughened portion 51b.

[0042] In this way, in battery 1, the maximum stress generated in insertion hole filling portion 74 can be reduced compared to when resin member 70 is not provided with step surrounding portion 75, which is a stress reducing portion, or when terminal member 50 is not provided with roughened end surface portions 52a, 52b. This makes it possible to suppress the occurrence of a defect such as that in battery C1 of the comparative embodiment, in which cracks occur in insertion hole filling portion 74 and the airtightness at the interface between terminal member 50 and resin member 70 decreases, resulting in battery 1 with improved reliability in terms of airtightness.

[0043] As shown in Fig. 3, in the step surrounding portion 75, a crack CL2 due to cohesive failure may occur along the roughened end surface 52a in a portion near the roughened end surface 52a where the generated stress is the highest in the resin member 70. In addition, a crack (not shown) due to cohesive failure may also occur along the roughened end surface 52b near the outer roughened end surface 52b. This is considered to be because the stress generated in these portions exceeds the strength of the resin material 70R. However, unlike the above-mentioned crack CL1, this crack CL2 does not affect the seal by the insertion hole filling portion 74 and does not reduce the airtightness at the interface between the terminal member 50 and the resin member 70.

[0044] Furthermore, in the step surrounding portion 75, which is the crack containing portion containing the crack CL2, the stress that had been generated in the step surrounding portion 75 before the crack occurred is released by the occurrence of the crack CL2, and thus the stress generated in the insertion hole filling portion 74 is also reduced, resulting in an even more stable state.

[0045] Next, a method for manufacturing the battery 1 of this embodiment will be described (see Figs. 5 to 8). First, an unroughened lid member 30 is prepared. The unroughened lid member 30 is obtained by pressing an aluminum plate. Also, an unroughened terminal member 50 is prepared. The unroughened terminal member 50 is obtained by pressing a metal plate (the positive electrode is an aluminum plate, and the negative electrode is a copper plate).

[0046] Then, in the terminal roughening step S1, the bent extension portion 50b of the above-mentioned terminal member 50 is intermittently irradiated with pulsed laser light LC while shifting the irradiation position, to form a belt-like annular first roughened portion 51 in which a large number of cup-shaped recesses 55 are arranged while partially overlapping each other (see Figs. 3 and 7). Similarly, the upper side AH1 of the inner end face 50ca and the outer end face 50cb of the stepped extension portion 50c of the terminal member 50 is intermittently irradiated with pulsed laser light LC while shifting the irradiation position, to form end face roughened portions 52a, 52b in which a large number of cup-shaped recesses 55 are arranged while partially overlapping each other (see Figs. 3 and 7).

[0047] Separately, in the lid roughening step S2, the peripheral portion 31 of the terminal insertion hole 30h of the lid member 30, and also the outer side surface 30s1 and the inner side surface 30s2 are intermittently irradiated with the pulsed laser light LC while shifting the irradiation position, to form a band-like annular lid seal outer roughened portion 31s1 and a lid seal inner roughened portion 31s2 in which a large number of cup-shaped recesses 35 are arranged while overlapping each other (see Figs. 3 and 7). The irradiation conditions of the pulsed laser light LC were the same as those when the positive electrode terminal member 50 was irradiated with a laser in the terminal roughening step S1.

[0048] Next, in the insert molding process S3, the 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. 6). Specifically, in a mold (not shown), the positive and negative terminal members 50 are inserted into the pair of terminal insertion holes 30h of the lid member 30, respectively, and molten resin material 70R is injected and welded to the peripheral portion 31 of the lid member 30 and parts of the top plate portion 50a, the bent extension portion 50b and the stepped extension portion 50c of the terminal member 50, and then cooled, whereby the pair of resin members 70 are insert molded. At this time, the molten resin material 70R is filled between the nanopillars 36 standing in the lid seal outer roughened portion 31s1 and the lid seal inner roughened portion 31s2 of the lid member 30, and between the nanopillars 56 standing in the first roughened portion 51 and the end face roughened portions 52a, 52b of the terminal member 50, and is firmly fixed.

[0049] Next, in the electrode body connecting process S4, the connection portion 50d of the positive terminal member 50 of the above-mentioned lid assembly 15 is welded to the positive current collecting portion 40p of the electrode body 40 prepared in advance (see Figs. 1, 2, and 6). Also, the connection portion 50d of the negative terminal member 50 of the lid assembly 15 is welded to the negative current collecting portion 40n of the electrode body 40. Thereafter, the electrode body 40 is wrapped in a bag-shaped insulating holder 7.

[0050] Next, in the electrode assembly housing / case formation 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 portion 30f of the lid member 30 are laser-welded airtightly around the entire periphery to form the case 10 housing the electrode assembly 40 therein.

[0051] Next, in a liquid filling and sealing step S6, electrolyte 5 is poured into case 10 through liquid filling hole 30k to impregnate electrolyte 5 into electrode body 40. Thereafter, liquid filling hole 30k is covered from the outside with liquid filling plug 12, which is then 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 to stand at high temperature (e.g., 60°C) for a predetermined time to age the battery 1. In this way, the battery 1 is completed.

[0052] The comparative battery C1 is manufactured in the same manner as the battery 1. However, in the terminal roughening step S1, the end surface roughened portions 52a, 52b are not formed on the inner end surface 50ca and the outer end surface 50cb of the stepped extending portion 50c of the terminal member 50, and only the band-shaped annular first roughened portion 51 is formed on the bent extending portion 50b (see FIG. 10).

[0053] (Variations) Next, a battery 101 according to a modified embodiment will be described with reference to the drawings. The battery 101 of this modified embodiment differs from the battery 1 of the above-described embodiment in the cross-sectional shape of the stepped extension 150c of the terminal member 150 and the shape of the roughened portion provided on this stepped extension 150c (see Figs. 8 and 9), but is otherwise similar. Therefore, the following description will focus on the different parts, and similar parts will be given the same reference numerals and descriptions thereof will be omitted or simplified.

[0054] The terminal member 150 used in the battery 101 has substantially the same shape as the terminal member 50 of the battery 1. However, as described above, the stepped extension portion 50c of the terminal member 50 has a rectangular cross-sectional shape, and roughened end surface portions 52a, 52b are formed on the upper side AH1 of the inner end surface 50ca facing the inner side BHI and the outer end surface 50cb facing the outer side BHO, respectively.

[0055] 8(b), the stepped extension 150c of the terminal member 150 has a cross-sectional shape of a rectangle with rounded corners. That is, in addition to flat surfaces 150cc, 150cd extending in the battery width direction BH, the corners are rounded and integrated with the end faces, and the stepped extension 150c has an inner end R face 151car facing the inner side BHI and an outer end R face 151cbr facing the outer side BHO. Then, the inner end R face 151car and the outer end R face 151cbr of the stepped extension 50c are formed with end R face roughened portions 125a, 152b, which are second roughened portions, on the upper side AH1 portions of the inner end R face 151car and the outer end R face 151cbr. As in the roughened end surface portions 52a, 52b of the battery 1, the roughened end R surface portions 152a, 152b of the battery 101 also have a forest of nanopillars 56, as shown in FIG. 4, in which particles 56p derived from the metal (aluminum or copper in this embodiment) constituting the terminal member 150 are linked together in a string-like manner to form columns, with the nanopillars 56 having a height ha of 50 nm or more (height ha is approximately 150 nm in this embodiment).

[0056] The roughened end R surface portions 152a, 152b of the stepped extension portion 150c are also filled with the resin material 70R constituting the resin member 70. Therefore, the stepped surrounding portion 75 of the resin member 70 surrounds the stepped extension portion 150c of the terminal member 150, and is firmly fixed to at least two of the roughened end R surface portions 152a, 152b of the stepped extension portion 150c.

[0057] Therefore, similar to the battery 1 of the embodiment, when the modified battery 101 is exposed to an environment at approximately room temperature or even lower, the stress generated in the insertion hole filling portion 74 of the resin member 70 near the outer end surface roughened portion 51b and the inner end surface roughened portion 51a of the first roughened portion 51 is significantly lower than that of the battery C1 (for example, approximately half or less even in this modified form).

[0058] On the other hand, in the resin member 70, a stress higher than the stress near the outer end surface roughened portion 51b of the first roughened portion 51 is generated near the outer end surface roughened portion 152b of the step surrounding portion 75. In addition, a stress higher than the stress near the inner end surface roughened portion 51a of the first roughened portion 51 is generated near the inner end surface roughened portion 152a, and the highest stress in the resin member 70 is generated.

[0059] Therefore, even in the modified battery 101, the maximum stress generated in the insertion hole filling portion 74 can be reduced compared to a case where the resin member 70 is not provided with the step surrounding portion 75 or where the terminal member 150 is not provided with the end R surface roughened portions 152a, 152b. This makes it possible to suppress the occurrence of a defect in which cracks are generated in the insertion hole filling portion 74 and the airtightness at the interface between the terminal member 50 and the resin member 70 decreases, resulting in battery 101 with improved reliability in terms of airtightness.

[0060] In addition, when comparing the battery 1 of the embodiment and the battery 101 of the comparative embodiment, the stress generated in the vicinity of the end R surface roughened parts 152a, 152b of the step surrounding part 75 in the battery 1 is relatively low compared to the stress generated in the vicinity of the end surface roughened parts 52a, 52b of the step surrounding part 75 in the battery 1. The reason for this is considered to be as follows. That is, as described above, in the battery 1, the step extension part 50c of the terminal member 50 has a rectangular cross section, so that stress is likely to concentrate near the corners and generate high stress. In contrast, in the battery 101 of the present modified embodiment, the step extension part 150c of the terminal member 150 has a rectangular cross section with rounded corners as described above. For this reason, it is considered that stress does not concentrate near the corners, and the stress generated in the vicinity of the end R surface roughened parts 152a, 152b of the step surrounding part 75 is relatively low.

[0061] As described above, in battery 1, as shown in Fig. 3, cracks CL2 due to cohesive failure sometimes occurred along rough end surface portion 52a in step surrounding portion 75. In addition, cracks sometimes occurred along outer rough end surface portion 52b.

[0062] In contrast, in battery 101, as can be seen from the fact that cracks CL2 are not shown in Fig. 8, cracks are less likely to occur in step surrounding portion 75 compared to battery 1. As described above, this is thought to be because the stress generated in step surrounding portion 75 is relatively low and is less likely to exceed the strength of resin material 70R. For this reason, batteries 101 that have undergone stress release due to the occurrence of cracks CL2 are less likely to be mixed with batteries that have not been stress released, and batteries 101 with stable quality can be obtained.

[0063] Although the present invention has been described above with reference to embodiments and modified forms, it goes without saying that the present invention is not limited to the embodiments, etc., and can be modified and applied as appropriate without departing from the spirit of the present invention. For example, in the embodiment, roughened end surfaces 52a, 52b are provided on the inner end surface 50ca and the outer end surface 50cb of the stepped extension portion 50c of the terminal member 50, respectively, but an example is shown in which no roughened portions are provided on the flat surfaces 50cc, 50cd facing the battery thickness direction CH. However, similarly to first rough portion 51, stepped extension portion 50c may also include end face rough portions 52a, 52b, and may be provided with a band-shaped, annular second rough portion surrounding stepped extension portion 50c.

[0064] Furthermore, the roughened surfaces with the nano pillars 36, 56 standing in rows were formed on the lid seal outer roughened portion 31s1, the first roughened portion 51, the roughened end surface portions 52a, 52b, etc. by irradiation with pulsed laser light LC. However, other roughening methods can also be used. For example, the roughened surface can be formed by physical roughening such as shot blasting, polishing, and thermal spraying, or chemical roughening such as anodizing. [Explanation of symbols]

[0065] 1,101,C1 Battery (energy storage device) 10 Cases 20 Case body parts (case parts) 30 Lid member (case member) 30h Terminal insertion hole 30hs (Terminal Hole) Inner Surface 31 Periphery 31s1 (of the lid member) outer lid seal roughened part 31s2 (Lid seal) inner roughened part 40 Electrode body 50,150 Terminal material 50a Top plate 50b Bend extension part 50c,150c step extension 50ca inner end 50cb outer edge 150car Inner end R surface 150cbr Outer end R surface 50d Connection 51 1st roughening section 51a Roughened inner end surface 51b Roughened outer end surface 51c,51d Roughened flat plate surface 52a, 52b End surface roughening part (second roughening part) 152a, 152b Edge R surface roughening part (second roughening part) 70,170 Resin material 70R resin material 71 Top board periphery 72 Outer peripheral area 73 Inner periphery 74 Insertion hole filling part (terminal seal part) 75 Step surrounding area (stress reduction area, crack containing area) 175 Step surrounding section (stress reducing section) CL1, CL2 crack LC Pulsed Laser Light

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 hermetically 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 terminal member is A first roughened portion having a ring-like shape and surrounding the terminal member; and A second roughened portion is provided, the second roughened portion being spaced apart from the first roughened portion, The resin member is The case member and the terminal member inserted into the terminal insertion hole are integrally insert-molded, a ring-shaped, strip-shaped terminal seal portion that is airtightly fixed to the first roughened portion of the terminal member; a stress reducing portion that is fixed to the second roughened portion of the terminal member and reduces stress generated in the terminal seal portion. Energy storage device.

2. The power storage device according to claim 1 , The stress reduction portion is a crack-containing portion that is fixed to the second roughened portion of the terminal member and that includes a crack due to cohesive failure along the second roughened portion; Energy storage device.

3. The electricity storage device according to claim 1 or 2, The first roughened portion of the terminal member is The particles originating from the terminal member are linked together in a string to form a columnar shape, forming nano-columns with a height of 50 nm or more. The terminal seal portion of the resin member is The resin material is filled between the adjacent nano-pillars and is fixed to the first roughened portion in an airtight manner. Energy storage device.

4. The electricity storage device according to claim 1 or 2, The second roughened portion of the terminal member is The particles originating from the terminal member are linked together in a string to form a columnar shape, forming nano-columns with a height of 50 nm or more. The stress reducing portion of the resin member is The resin material is filled between the adjacent nano-pillars and is fixed to the second roughened portion. Energy storage device.

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