Energy Storage Devices

Abstract

To realize a power storage device in which malfunction hardly occurs even in a case where a temperature change occurs.SOLUTION: A battery 1 includes: a case 10 that includes a metal lid member 30 provided with an insertion hole 33h; a terminal member 50 that is inserted into the insertion hole 33h; and a resin member 70 that isolates the case 10 from the terminal member 50. An annular-like hole peripheral region 33S that surrounds the insertion hole 33h and tightly fixes a resin member 70 and an outside region 33T to which the resin member 70 is brought into contact exist on a surface 33 directed to an outside of the lid member 30. A two-region length LST that has a length of a two-region formed by two of the hole peripheral region 33S and the outside region 33T is a length having a two-region length ratio of 3.0 or more as a ratio of a maximum two-region length LSTmax relative to a minimum two-region length LSTmin. A seal length LS that is the length of the hole peripheral region 33S is a length having a seal length ratio as a ratio of the maximum seal length LSmax relative to the maximum seal length LSmin of 1.4 or less.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The technical field disclosed in this specification relates to electricity storage devices. [Background technology]

[0002] As an electricity storage device, a rectangular battery in which positive and negative terminal members are fixed to a rectangular box-shaped case via a resin member is known. In such an electricity storage device, for example, the case is made up of a bottomed rectangular cylindrical main body member having a rectangular annular opening, and a rectangular plate-shaped lid member laser-welded to the main body member over the entire circumference in a form that closes the opening. The positive and negative terminal members are inserted into a pair of insertion holes provided in the lid member, respectively, and extend from the inside of the case to the outside of the case. The resin member insulates between the lid member and the positive and negative terminal members, respectively, while joining to the lid member and the terminal members, respectively, and seals them to maintain airtightness. For example, Patent Document 1 can be cited as a related prior art. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-086813 Summary of the Invention [Problem to be solved by the invention]

[0004] The thermal expansion coefficients of the metal case and the resin member bonded to the case are different. Therefore, for example, in a thermal test, when the power storage device is exposed to a low temperature, the resin member shrinks more, resulting in a difference in thermal expansion. As a result, the resin member near the insertion hole of the case may break, causing problems such as loss of airtightness and destruction of insulation between the case and the terminal member. [Means for solving the problem]

[0005] The electricity storage device devised for solving the above-mentioned problems is as follows: A metal case member having an insertion hole; A terminal member inserted into the insertion hole; an electrode body housed in the case member and connected to the terminal member; a resin member that insulates the case member from the terminal members and is in contact with the case member and the terminal members; A power storage device comprising: The surface of the case member facing outward has a region in contact with the resin member, In an annular region surrounding the insertion hole And in areas where the surface has been roughened a seal area for airtightly fixing the resin member; a contact area located radially outward of the insertion hole relative to the sealing area and in contact with the resin member; There is Regarding a two-region length LST, which is the length of the two regions consisting of the sealing region and the contact region, a two-region length ratio, which is the ratio of the maximum two-region length LSTmax to the minimum two-region length LSTmin, is 3.0 or more; The portion of the contact region that is the maximum two-region length LSTmax includes a resin injection portion during insert molding, Regarding the seal length LS, which is the length of the seal area, the seal length ratio, which is the ratio of the maximum seal length LSmax to the minimum seal length LSmin, is 1.4 or less. The power storage device is configured as follows.

[0006] According to the above-mentioned electric storage device, the surface facing the outside of the case member has an annular seal area around the insertion hole where the resin member is fixed airtight, and the seal length ratio of the seal area is configured to be 1.4 or less. In addition, the area other than the annular seal area is configured as an abutment area where the resin member is not fixed but is only abutted. By configuring in this way, the area of ​​the surface facing the outside of the case member that contacts the resin member around the insertion hole has a small seal length variation even in an area where the two-area length ratio of the two areas consisting of the seal area and the abutment area is 3.0 or more and the variation in the two-area length LST is large. Therefore, the stress caused by the thermal expansion difference between the resin member and the metal is unlikely to become large, and is unlikely to be concentrated in a specific location of the seal area. As a result, it is possible to suppress the decrease in airtightness and the breakdown of insulation caused by temperature changes. Effect of the Invention

[0007] According to the technology disclosed in this specification, an electricity storage device that is less likely to malfunction even when a temperature change occurs is realized. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view of a battery according to an embodiment. [Diagram 2] 1 is a cross-sectional view of a battery according to an embodiment taken along a battery height direction and a battery width direction. [Diagram 3] 4 is a view showing the upper side of the lid member, in the vicinity of the opening of the body member and the peripheral edge of the lid member of the battery according to the embodiment; FIG. [Figure 4] 4 is a partially enlarged cross-sectional view (cross-sectional view taken along line AA in FIG. 3) of the vicinity of the opening of the body member and the peripheral edge of the lid member of the battery according to the embodiment, taken along the battery height direction and battery width direction. [Diagram 5] 2 is a flowchart of a method for manufacturing a battery according to an embodiment. [Figure 6] FIG. 4 is a schematic diagram showing a state in which the surface of the lid member according to the embodiment is roughened. [Figure 7] 11A-11C are diagrams showing the lid assembly formed in the lid assembly forming step. [Figure 8] 13 is an explanatory diagram showing the state in which molten resin is injected into a mold in the lid assembly forming process. FIG. [Figure 9] 13 is a view showing the upper side of the lid member, near the opening of the body member and the peripheral edge of the lid member of the battery according to the comparative example. FIG. [Figure 10] 1 is a partially enlarged cross-sectional view of the vicinity of an opening of a body member and a peripheral portion of a lid member of a battery according to a comparative example, taken along the battery height direction and battery width direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, a battery 1 according to an embodiment will be described with reference to Figs. 1 to 4. The battery 1 is an example of an electricity storage device. 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 to 4. The 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.

[0010] [Battery configuration] 1 and 2, the battery 1 has a rectangular parallelepiped case 10 made of metal (aluminum in this embodiment), an electrode body 40 housed in the case 10, and further has a positive electrode terminal member 50 supported via a resin member 70 and a negative electrode terminal member 60 supported via a resin member 80 at an upper portion 11 constituting a portion of the upper side AH1 of the case 10 in the battery height direction AH. The electrode body 40 is covered in a bag-shaped insulating holder 5 made of an insulating film within the case 10. An electrolyte 3 is housed within the case 10, a portion of which is immersed in the electrode body 40, and the remainder is collected in a bottom portion 12 constituting a portion of the lower side AH2 of the case 10 in the battery height direction AH.

[0011] The case 10 is composed of a main body member 20 and a lid member 30. The main body member 20 is in the shape of a rectangular cylinder with a bottom having a rectangular annular opening 21 on the upper side AH1 in the battery height direction AH. Specifically, the main body member 20 forms a bottom 12 of the case 10, a long side portion 13 constituting a portion of one side CH1 of the case 10 in the battery thickness direction CH, a long side portion 14 constituting a portion of the other side CH2 of the case 10 in the battery thickness direction CH, a short side portion 15 constituting a portion of one side BH1 of the case 10 in the battery width direction BH, and a short side portion 16 constituting a portion of the other side BH2 of the case 10 in the battery width direction BH. On the other hand, the lid member 30 is in the shape of a rectangular plate and forms the upper portion 11 of the case 10. The lid member 30 is in a form that closes the opening 21 of the main body member 20, and the peripheral portion 31 of the lid member 30 is laser welded around the entire circumference of the opening 21 of the main body member 20, and a molten and solidified portion 18 is formed between the lid member 30 and the main body member 20.

[0012] The cover member 30 is provided with a safety valve 19 that breaks and opens when the internal pressure of the case 10 exceeds a valve opening pressure. Furthermore, the cover member 30 is formed with a liquid injection hole 30k that penetrates from the inside to the outside of the case 10, and a disk-shaped sealing member 39 made of aluminum is inserted into the liquid injection hole 30k to provide an airtight seal.

[0013] In addition, a rectangular insertion hole 33h penetrating in the lid thickness direction DH is provided near the end of one side BH1 of the battery width direction BH of the lid member 30, and a rectangular insertion hole 34h penetrating in the lid thickness direction DH is provided near the end of the other side BH2 of the battery width direction BH. A positive electrode terminal member 50 made of aluminum is inserted into the insertion hole 33h, and the positive electrode terminal member 50 is fixed to the lid member 30 in a state insulated from the lid member 30 via a resin member 70. A negative electrode terminal member 60 made of copper is inserted into the insertion hole 34h, and the negative electrode terminal member 60 is fixed to the lid member 30 in a state insulated from the lid member 30 via a resin member 80.

[0014] The positive electrode terminal member 50 is on the cover member 30 and has a rectangular plate-shaped external terminal portion 51 including a surface 53 exposed toward the outside DH1 in the cover thickness direction DH of the cover member 30, and an internal terminal portion 52 disposed inside the case 10 and in the insertion hole 33h of the cover member 30. The negative electrode terminal member 60 is on the cover member 30 and has a rectangular plate-shaped external terminal portion 61 including a surface 63 exposed toward the outside DH1 in the cover thickness direction DH of the cover member 30, and an internal terminal portion 62 disposed inside the case 10 and in the insertion hole 34h of the cover member 30. The positive electrode internal terminal portion 52 is joined to the positive electrode current collector of the electrode body 40 in the case 10 and is electrically connected. The negative electrode internal terminal portion 62 is joined to the negative electrode tab 40b of the electrode body 40 in the case 10 and is electrically connected.

[0015] The electrode body 40 is a flat rectangular parallelepiped, and is a laminated electrode body in which a plurality of positive electrode plates 41 and a plurality of negative electrode plates 42, each of which has a rectangular shape extending in the battery height direction AH and the battery width direction BH, are alternately laminated in the battery thickness direction CH via a separator 43 made of a porous resin film. Each positive electrode plate 41 has a positive electrode current collector 41r extending to one side BH1 of the battery width direction BH, and the positive electrode current collectors 41r overlap each other in the thickness direction to form the above-mentioned positive electrode tab 40a. This positive electrode tab 40a is connected to the internal terminal portion 52 of the positive electrode terminal member 50 as described above. Each negative electrode plate 42 has a negative electrode current collector 42r extending to the other side BH2 of the battery width direction BH, and the negative electrode current collectors 42r overlap each other in the thickness direction to form the above-mentioned negative electrode tab 40b. This negative electrode tab 40b is connected to the internal terminal portion 62 of the negative electrode terminal member 60 as described above.

[0016] The positive electrode resin member 70 contacts the cover member 30 and the terminal member 50 while providing insulation between the cover member 30 and the terminal member 50, and portions of the positive electrode resin member 70 are fixed to the cover member 30 and the terminal member 50. Similarly, the negative electrode resin member 80 contacts the cover member 30 and the terminal member 60 while providing insulation between the cover member 30 and the terminal member 60, and portions of the negative electrode resin member 80 are fixed to the cover member 30 and the terminal member 50.

[0017] The resin member 70 is made of polyphenylene sulfide (PPS) and has an external insulating part 71 arranged on the lid member 30 and an internal insulating part 72 arranged inside the case 10 and in the insertion hole 33h of the lid member 30, the internal insulating part 72 being connected to the external insulating part 71 via the insertion hole 33h of the lid member 30. The resin member 80 is also made of PPS and has an external insulating part 81 arranged on the lid member 30 and an internal insulating part 82 arranged inside the case 10 and in the insertion hole 34h of the lid member 30, the internal insulating part 82 being connected to the external insulating part 81 via the insertion hole 34h of the lid member 30.

[0018] 3 and 4, the external insulating portion 71 of the resin member 70 has a frame shape surrounding the external terminal 51, and specifically has an external surface portion 71m1 on one side BH1 in the battery width direction BH from the external terminal 51, an external surface portion 71m2 on the other side BH2 in the battery width direction BH from the external terminal 51, an external surface portion 71m3 on one side CH1 in the battery thickness direction CH from the external terminal 51, and an external surface portion 71m4 on the other side CH2 in the battery thickness direction CH from the external terminal 51. Each of the external surface portions 71m1, 71m2, 71m3, and 71m4 is connected to an internal insulating portion 72 of the resin member 70 within the insertion hole 33h.

[0019] The width of the outer surface portion 71m1 (length in the battery width direction BH), the width of the outer surface portion 71m3 (length in the battery thickness direction CH), and the width of the outer surface portion 71m4 (length in the battery thickness direction CH) are approximately equal. The outer surface portion 71m2 has a shape having a protrusion 71mG that protrudes to the other side BH2 in the battery width direction BH. The resin member 70 is formed by insert molding, which will be described later, and the protrusion 71mG is a location where a gate member GT (see FIG. 8) into which molten resin is injected during the insert molding is disposed. Therefore, the width of the outer surface portion 71m2 (length in the battery width direction BH) is wider at a location that includes the protrusion 71mG than at a location that does not include the protrusion 71mG. The width of the location that does not include the protrusion 71mG is approximately equal to the width of the outer surface portion 71m1.

[0020] The surface 33 of the cover member 30 facing the outer side DH1 in the cover thickness direction DH has a rectangular annular hole surrounding region 33S surrounding the insertion hole 33h, and an outer region 33T located outside (away from the insertion hole 33h) in the radial direction (the direction in which the insertion hole 33h expands) of the insertion hole 33h, as regions in contact with the resin member 70. The length of the hole surrounding region 33S (the radial length of the insertion hole 33h) is almost uniform around the entire circumference of the insertion hole 33h. The "length of the hole surrounding region 33S" is also referred to as the "width of the hole surrounding region 33S."

[0021] The hole surrounding area 33S of the surface 33 of the lid member 30 is roughened to form fine irregularities. In such a roughened area, the adhesion between the metal lid member 30 and the resin member 70 is enhanced, and furthermore, due to the anchor effect, the adhesive strength between the lid member 30 and the resin member 70 is higher than that in the outer area 33T that is not roughened. The surface 33 of the lid member 30 is provided with the hole surrounding area 33S having this high adhesive strength so as to surround the insertion hole 33h, and the resin member 70 is fixed airtightly by the hole surrounding area 33S. The hole surrounding area 33S is an example of a sealing area.

[0022] On the other hand, in the outer region 33T that has not been subjected to the roughening treatment, although it is in contact with the resin member 70, the adhesive strength is lower than that of the roughened region. That is, the resin member 70 is not fixed to the outer region 33T, but is in a state where the resin member 70 is in contact with the outer region 33T. For example, the protrusion 71mG on the outer surface portion 71m2 is in contact with the outer region 33T of the surface 33 of the lid member 30, and is not fixed to the lid member 30. The outer region 33T is an example of an abutting region.

[0023] Like surface 33 of cover member 30, surface 34 facing inward DH2 in the cover thickness direction DH of cover member 30 also has, as regions in contact with resin member 70, a rectangular annular hole peripheral region surrounding insertion hole 33h and an outer region positioned radially outward of insertion hole 33h than the hole peripheral region of surface 34, and while the hole peripheral region of surface 34 is also roughened, the outer region of surface 34 is not roughened. The width of the hole peripheral region of surface 34 is approximately equal to the width of hole peripheral region 33S of surface 33.

[0024] Furthermore, among the surfaces 33, 34 of the lid member 30, the surface on the side of the insertion hole 34h of the lid member 30 also has a rectangular annular region surrounding the insertion hole 34h, similar to the surface on the side of the insertion hole 33h, which is a region that has been roughened to form fine irregularities and has approximately the same width as the hole surrounding region 33S, and which hermetically bonds the lid member 30 and the resin member 80 together.

[0025] The positive electrode terminal member 50 also has a region where fine irregularities are formed by roughening a part of the surface that contacts the resin member 70, and such a region is provided all around the surface of the terminal member 50, thereby hermetically fixing the positive electrode terminal member 50 and the resin member 70. The negative electrode terminal member 60 also has a region where fine irregularities are formed by roughening a part of the surface that contacts the resin member 80, and thus hermetically fixing the negative electrode terminal member 60 and the resin member 80.

[0026] The regions on the surface 33 of the cover member 30 that are in contact with the resin member 70 have the following relationship. That is, the seal length LS, which is the length of the hole surrounding region 33S to which the resin member 70 is fixed (the radial length of the insertion hole 33h), has a seal length ratio, which is the ratio of the maximum seal length LSmax to the minimum seal length LSmin, of 1.4 or less, and more preferably 1.2 or less. That is, the length of the hole surrounding region 33S is almost uniform over the entire circumference of the insertion hole 33h. The seal length is the minimum length that a straight line passing only through the hole surrounding region 33S can reach from a certain point on the inner peripheral edge of the hole surrounding region 33S (the radially inner edge of the insertion hole 33h) to the outer peripheral edge of the hole surrounding region 33S (the radially outer edge of the insertion hole 33h) toward the radially outer side of the insertion hole 33h.

[0027] In addition, since a part of the outer surface portion 71m2 forms the protrusion 71mG, in the region on the surface 33 of the cover member 30 that contacts the resin member 70, the width of the outer region 33T is larger at the point where the protrusion 71mG contacts. On the other hand, the width of the outer region 33T is narrower at other points, and the width is also almost uniform. Therefore, the two-region length LST, which is the length of the two regions 332 consisting of the hole-surrounding region 33S and the outer region 33T, is larger at the point where the protrusion 71mG contacts compared to the two-region length LST at other points. The two-region length LST is the maximum length that a straight line passing only through the two regions 332 can reach from a certain point on the inner periphery of the hole-surrounding region 33S to the outer periphery of the outer region 33T in the radial direction of the insertion hole 33h (the direction in which the hole-surrounding region 33S spreads) outward.

[0028] Specifically, in this embodiment, the two-region length LST, which is the length of the two regions 332 consisting of the hole-surrounding region 33S and the outer region 33T, has a two-region length ratio, which is the ratio of the maximum two-region length LSTmax to the minimum two-region length LSTmin, of 3.0 or more. Although the widths of the two regions, the hole-surrounding region 33S and the outer region 33T (i.e., the radial length of the outer insulating part 71 of the insertion hole 33h) vary greatly around the entire circumference of the insertion hole 33h, the width of the hole-surrounding region 33S fixed to the surface 33 of the lid member 30 (i.e., the width of the hole-surrounding region 33S) is approximately uniform around the entire circumference of the insertion hole 33h.

[0029] [Battery manufacturing] Next, a method for manufacturing the battery 1 will be described with reference to the flowchart of Fig. 5. First, in a "lid member preparation step S0", a lid member 30 is prepared. An aluminum plate is used for the lid member 30, and the liquid injection hole 30k, the insertion holes 33h, 34h, and the safety valve 19 are formed in advance by pressing or the like to obtain the lid member 30. The positive electrode terminal member 50 is made of an aluminum plate, and the negative electrode terminal member 60 is made of a copper plate, and each is obtained by pressing or the like.

[0030] Then, the area of ​​the surface 33 of the lid member 30 obtained by pressing or the like is roughened, the area corresponding to the hole surrounding area 33S, etc. Specifically, the following procedure is performed for each area of ​​the lid member 30 to be roughened, such as the hole surrounding area 33S. First, a laser beam is irradiated onto a first area in the area to be roughened, and the first area is melted. As the metal lid member 30 melts, metal particles are generated from the metal vapor or plasma released into the atmosphere, and the particles are deposited again in the first area or its periphery.

[0031] Then, a second region adjacent to the first region is irradiated with a laser beam, the second region is melted, and metal particles are deposited in the same manner as in the first region. By irradiating the laser beam in this manner over the entire region to be roughened, as shown in FIG. 6, a plurality of depressions 33L due to the laser beam and a plurality of protrusions 33R due to the deposition of metal particles are formed in the region to be roughened, and fine irregularities of the nm order are formed on the surface of the entire region to be roughened, for example, a hole surrounding region 33S is formed on the surface 33 of the cover member 30. Note that the terminal members 50 and 60 are also subjected to a roughening process in a predetermined region.

[0032] Next, in the "lid assembly forming step S1", a lid assembly 7 as shown in Fig. 7 is formed. The lid assembly 7 is a member in which the surface-roughened lid member 30, the surface-roughened terminal members 50, 60, the resin members 70, 80, and the electrode body 40 of the battery 1 are integrated together, and the electrode body 40 is wrapped in an insulating holder 5. In the lid assembly forming step S1, the lid member 30 and the terminal members 50, 60 are prepared, and the resin members 70, 80 are insert-molded to integrate the terminal members 50, 60 with the lid member 30 via the resin members 70, 80.

[0033] Specifically, in the lid assembly forming step S1, as shown in FIG. 8, the lid member 30 is placed at a predetermined position in the lower die DE2 of the die DE having an upper die DE1 and a lower die DE2. Then, the terminal members 50 and 60 are inserted into the insertion holes 33h and 34h of the lid member 30 placed in the lower die DE2, respectively. Then, the upper die DE1 is placed on the lower die DE2 and the die DE is closed. Next, the molten resin MR is injected into the die DE and then cooled to form the resin members 70 and 80. Then, the upper die DE1 is moved upward, and the composite molded product in which the terminal members 50 and 60 are integrated with the lid member 30 via the resin members 70 and 80 is taken out from the lower die DE2.

[0034] In this embodiment, since the resin member 70 is formed by insert molding, a region that connects to a gate member GT through which molten resin MR is injected into the mold DE is provided in the resin member 70. A protrusion 71mG provided on an outer surface portion 71m2 of the outer insulating portion 71 of the resin member 70 becomes the region that connects to this gate member GT.

[0035] Next, an electrode body 40 formed by stacking a positive electrode plate 41, a negative electrode plate 42, and a separator 43 is prepared, and the internal terminal portions 52, 62 of the terminal members 50, 60 of the above-mentioned composite molded product are connected by welding to the positive electrode tab 40a and the negative electrode tab 40b of the electrode body 40, respectively. After that, the electrode body 40 is wrapped in a bag-shaped insulating holder 5. In this way, a lid assembly 7 consisting of the lid member 30, the terminal members 50, 60, the resin members 70, 80, the electrode body 40, and the insulating holder 5 is formed.

[0036] Next, in the "closing process S2", a main body member 20 is prepared, and the electrode body 40 covered with an insulating holder 5 of the lid assembly 7 formed in the lid assembly formation process S1 is inserted into the main body member 20, and the peripheral portion 31 of the lid member 30 is used to close the opening 21 of the main body member 20.

[0037] Next, in the "welding process S3", laser light is irradiated from the outside DH1 in the lid thickness direction DH of the lid member 30 (upper side AH1 in the battery height direction AH) to the opening 21 of the main body member 20 and the peripheral portion 31 of the lid member 30 to form a molten and solidified portion 18, performing laser welding around the entire circumference to form the case 10.

[0038] Next, in a "pouring and sealing process S4", the electrolyte 3 is poured into the case 10 through the pouring hole 30k, and the electrolyte 3 is impregnated into the electrode body 40. Thereafter, the pouring hole 30k is covered from the outside with a sealing member 39, and the sealing member 39 is welded to the lid member 30 around its entire periphery to hermetically seal the gap between the sealing member 39 and the lid member 30.

[0039] Next, in the "initial charging and aging step S5", 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 for a predetermined period of time to age the battery 1. In this way, the battery 1 is completed.

[0040] As described above, when the resin member 70 and the lid member 30 are integrated by insert molding, the external insulating part 71 in contact with the surface 33 of the lid member 30 needs a protrusion 71mG where the gate member GT is arranged. In order to strongly fix the resin member 70 and the lid member 30 and increase the airtightness between the resin member 70 and the lid member 30, it is considered to widen the sealing area, which is the fixing area, that is, to roughen the entire area in contact with the resin member 70. For example, in the case of a battery 1, it is considered to roughen the gate arrangement area 33G in the surface 33 of the lid member 30 that is in contact with the protrusion 71mG where the gate member GT is arranged when the molten resin MR is injected in the insert molding, as shown in Figs. 9 and 10.

[0041] However, the linear expansion coefficients of the metal cover member 30, for example, aluminum in the battery 1 of this embodiment, and the resin member 70, for example, PPS in the battery 1 of this embodiment, are different. Therefore, when the width of a part of the sealing region is widened, if a thermal expansion difference (thermal contraction difference) occurs in an environment with a large temperature change, for example, in a thermal test, the resin member 70 near the hole surrounding region 33S may break due to stress applied to that part, particularly tensile stress applied in the radial direction of the insertion hole 33h. If the breakage occurs at a location away from the insertion hole 33h, it is unlikely to affect the airtightness or insulation, but if the breakage occurs near the insertion hole 33h, there is a high possibility that the airtightness will decrease or the insulation will be destroyed.

[0042] In contrast, in the battery 1 of the embodiment, the surface 33 of the cover member 30 facing the outside DH1 in the cover thickness direction DH has an annular hole surrounding region 33S that hermetically fastens the resin member 70 around the insertion hole 33h, and the seal length LS, which is the length of the hole surrounding region 33S, is configured so that its seal length ratio (maximum seal length LSmax / minimum seal length LSmin) is 1.4 or less. In addition, the area other than the annular hole surrounding region 33S is an outer region 33T that is only abutted without being fastened to the resin member. With this configuration, the surface 33 of the cover member 30 that contacts the resin member 70 around the insertion hole 33h has a small variation in the seal length LS even in a region where the two-region length ratio (maximum two-region length LSTmax / minimum two-region length LSTmin) of the two regions consisting of the hole surrounding region 33S and the outer region 33T is 3.0 or more, and the two-region length LST is large. Therefore, stress caused by the difference in thermal expansion between the resin member 70 and the metal cover member 30 is unlikely to increase, and stress is unlikely to concentrate at a specific location in the hole surrounding area 33S. As a result, it is possible to suppress the deterioration of airtightness and the breakdown of insulation caused by temperature changes.

[0043] It should be noted that this embodiment is merely an example and does not limit the present invention in any way. Therefore, the present invention can be naturally improved and modified in various ways without departing from the scope of the present invention. For example, in the embodiment, a laminated electrode body 40 is exemplified as the electrode body housed in the case 10, but the electrode body may be a flat wound electrode body. Also, a plurality of electrode bodies may be housed in the case.

[0044] Furthermore, although the embodiment is applied to a lithium ion battery, the present invention can be applied to any general power storage device, for example, a nickel-metal hydride battery or a nickel-cadmium battery.

[0045] In addition, in the embodiment, as a roughening treatment, a metal deposit (anchor) is formed on the metal surface by a laser beam, but any general roughening treatment can be applied, for example, pores may be formed on the metal surface by an acid-based etching agent.

[0046] In addition, in the embodiment, the hole surrounding region 33S of the surface 33 of the cover member 30 is located radially outward from the insertion hole 33h, but it is not necessarily located strictly from the insertion hole 33h, and there may be an area between the insertion hole 33h and the inner edge of the hole surrounding region 33S that is not roughened.

[0047] In addition, in the embodiment, the outer surface portion 71m2 of the resin member 70 has an uneven shape having the protrusions 71mG, but the shape of the outer surface portion 71m2 is not limited to this and may be, for example, a rectangle that includes the area where the gate member GT is to be positioned. [Explanation of symbols]

[0048] 1. Battery (energy storage device) 10 Cases 20 Main body parts 30 Lid member 33h Through hole 33S Area around the hole (seal area) 33T Outer area (contact area) 50 Terminal material 70 Resin parts

Claims

1. A metal case member having an insertion hole; A terminal member inserted into the insertion hole; an electrode body housed in the case member and connected to the terminal member; a resin member that insulates the case member from the terminal members and is in contact with the case member and the terminal members; A power storage device comprising: The surface of the case member facing outward has a region in contact with the resin member, a seal area that is an annular area surrounding the insertion hole and that has been subjected to a surface roughening treatment, and that hermetically fixes the resin member; a contact area that is located radially outward of the insertion hole relative to the sealing area and that contacts the resin member; There is Regarding a two-area length LST, which is a length of the two areas consisting of the sealing area and the contact area, a two-area length ratio, which is a ratio of a maximum two-area length LSTmax to a minimum two-area length LSTmin, is 3.0 or more; The portion of the contact region that is the maximum two-region length LSTmax includes a resin injection portion during insert molding, Regarding the seal length LS, which is the length of the seal area, the seal length ratio, which is the ratio of the maximum seal length LSmax to the minimum seal length LSmin, is 1.4 or less. The power storage device is configured as follows.

2. The electricity storage device according to claim 1 , With respect to the seal length LS, the seal length ratio is 1.2 or less; The power storage device is configured as follows.

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