Electricity storage device and method for manufacturing the same

Abstract

To provide: a power storage device in which formation of cracks in a resin member can be curbed when the power storage device is placed at room temperature (25°C); and the like.SOLUTION: A power storage device 1 includes a case member 30, terminal members 50, 60, and resin members 70, 80 subjected to insert molding to fix the terminal member 50, 60, respectively, to the case member 30. The resin members 70, 80 each are made of a resin material 75 including a thermoplastic main resin 76 having a first glass transition temperature Tg1 equal to or higher than 70°C, a thermoplastic elastomer 77, and a filler 78. The elastomer 77 has a second glass transition temperature Tg2 that is equal to or higher than -10°C and equal to or lower than 20°C and a third glass transition temperature Tg3 equal to or lower than -40°C.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an electricity storage device in which terminal members are fixed to case members constituting a case via a resin member, and to a method for manufacturing the electricity storage device. [Background technology]

[0002] A known power storage device is a battery in which positive and negative terminal members are fixed via a resin member to a case member (specifically, a rectangular plate-shaped case lid member) that forms a rectangular box-shaped case. Specifically, the positive and negative terminal members are inserted into insertion holes provided in the case lid member and extend from the inside to the outside of the case, and the resin member hermetically joins the case lid member and the terminal members while insulating them from each other, thereby fixing the terminal members to the case lid member.

[0003] When manufacturing such a battery, a resin member may be insert-molded. That is, the resin member is insert-molded with the terminal member inserted into the insertion hole of the case lid member, and the terminal member is fixed to the case lid member via the resin member. Note that, for example, Patent Document 1 (see Figures 2, 6, 7, etc.) is an example of a conventional technique for insert-molding a resin member in this manner. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-079172 Summary of the Invention [Problem to be solved by the invention]

[0005] To secure the terminal member to the case lid member with a resin member, the resin member must have a certain degree of hardness. For this reason, the resin member may be made of a resin with a glass transition temperature Tg1 that is sufficiently higher than room temperature (25°C), such as polyphenylene sulfide (PPS: glass transition temperature Tg1 = 90°C). In addition, in order to further improve the strength of the resin member or to bring the linear expansion coefficient of the resin material that makes up the resin member closer to the linear expansion coefficient of the metal that makes up the terminal member or case member, fillers such as glass fiber, carbon fiber, ceramic powder, etc. may be further added to the resin material. On the other hand, in order to increase the toughness of the resin member, an elastomer that is easily elastically deformed may be further added to the resin material. The added elastomer disperses the stress applied to the resin member, preventing the occurrence and propagation of cracks in the resin member when the resin member is molded and cooled to room temperature or during actual use of the battery.

[0006] However, even when a resin part is molded using a resin material containing such a main resin, elastomer, and filler, if the temperature of the resin part is returned to room temperature (25°C) after molding, stress caused by the difference in thermal expansion between the case part and terminal part on the one hand and the resin part on the other hand may cause cracks (fissures) along the boundary due to cohesive failure in the part of the resin part near the boundary with the terminal part on the other hand.

[0007] The present invention has been made in consideration of the current situation and provides an electricity storage device in which a resin member is molded using a resin material containing a main resin, an elastomer, and a filler, the main resin having a first glass transition temperature Tg1 that is sufficiently higher than room temperature, and which can suppress the occurrence of cracks in the resin member when the electricity storage device is placed at room temperature (25°C), and a method for manufacturing the electricity storage device. [Means for solving the problem]

[0008] (1) One aspect of the present invention for solving the above problem is an electricity storage device comprising: a case member having an insertion hole; terminal members inserted into the insertion hole of the case member; and an insert-molded resin member that hermetically joins the case member and the terminal members while insulating them from each other and fixing the terminal members to the case member, wherein the resin member is made of a resin material containing a thermoplastic main resin having a first glass transition temperature Tg1 (Tg1≧70) of 70°C or higher, a thermoplastic elastomer, and a filler, and the elastomer has a second glass transition temperature Tg2 (−10≦Tg2≦20) of −10°C or higher and 20°C or lower, and a third glass transition temperature Tg3 (Tg3≦−40) of −40°C or lower.

[0009] In the above-described electricity storage device, the main resin of the resin material constituting the resin member has a first glass transition temperature Tg1 of 70° C. or higher, while the elastomer has a second glass transition temperature Tg2 of −10° C. or higher and 20° C. or lower, and a third glass transition temperature Tg3 of −40° C. or lower. This makes it possible to prevent cracks from occurring in the resin member when the electricity storage device is placed at room temperature (25° C.).

[0010] The reason for this is believed to be as follows: The glass transition temperature Tg1 of the main resin contained in the resin material is sufficiently higher than room temperature, so the main resin is in a glassy state at room temperature, which makes it hard and strong but has low toughness. Here, consider the case where the elastomer contained in the resin material has only one glass transition temperature Tg2, or two glass transition temperatures Tg2 and Tg3, and both of these glass transition temperatures Tg2 and Tg3 are higher than room temperature or slightly lower than room temperature (specifically, −10 to 25°C) (i.e., −10°C or higher). In this case, when the temperature of the resin member is at room temperature, the elastomer is in a glassy state, or the elastomer is in a hard state because room temperature is close to the glass transition temperatures Tg2 and Tg3. Therefore, the resin member (resin material) becomes hard and elastic. If there is a difference in thermal expansion between the case member and the terminal member and the resin member, large stress is applied to the resin member, making the resin member prone to cracking.

[0011] On the other hand, consider a case where only one of the elastomers has a glass transition temperature Tg2, or both of the elastomers have a glass transition temperature Tg2 and Tg3 that are sufficiently lower than room temperature (specifically, −40°C or lower). In this case, the elastomer is in a sufficiently soft, rubber-like elastic state when the resin member is at room temperature. Therefore, if there is a difference in thermal expansion between the case member and the terminal member and the resin member, the elastomer is too soft and easily deforms, preventing sufficient stress dispersion. This places a large stress on the main resin of the resin member, making the resin member prone to cracking.

[0012] In contrast, in the present invention, as described above, the elastomer contained in the resin material has a second glass transition temperature Tg2 slightly lower than room temperature (−10 to 20°C) and a third glass transition temperature Tg3 sufficiently lower than room temperature (−40°C or lower). Therefore, when the temperature of the resin member is at room temperature, a portion of the elastomer is hard because the second glass transition temperature Tg2 is close to room temperature, but the remainder of the elastomer remains sufficiently soft because the third glass transition temperature Tg3 is sufficiently lower than room temperature, and it is believed that the elastomer as a whole has a moderate hardness (moderate softness). As a result, even if there is a difference in thermal expansion between the case member and the terminal member and the resin member, the elastomer with a moderate hardness deforms and distributes stress, reducing the stress applied to the main resin of the resin member and preventing cracks from occurring in the resin member.

[0013] In addition, when the glass transition temperature Tg2 of only one of the elastomers or both of the glass transition temperatures Tg2 and Tg3 are within the temperature range (above -40°C and below -10°C) between the two temperature ranges (above -10°C and below -40°C) mentioned above, the elastomer maintains an appropriate hardness even when the resin member is at room temperature. Therefore, the elastomer deforms and distributes stress, reducing the stress applied to the main resin of the resin member and making the resin member less likely to crack. However, in these cases, even a slight decrease in the temperature of the energy storage device from room temperature (for example, about 10 to 20°C) tends to increase the hardness of the elastomer as a whole, thereby weakening the stress-reducing effect of the elastomer.

[0014] In contrast, in the present invention, as described above, the elastomer has two mutually distant glass transition temperatures: a second glass transition temperature Tg2 that is slightly lower than room temperature (-10 to 20°C), and a third glass transition temperature Tg3 that is sufficiently lower than room temperature (-40°C or lower). Therefore, even if the temperature at which the electricity storage device is maintained drops slightly from room temperature, the elastomer maintains an appropriate level of softness, maintaining the stress-reducing effect of the elastomer and preventing cracks from occurring in the resin member.

[0015] Examples of the "electricity storage device" include secondary batteries such as lithium ion secondary batteries, sodium ion secondary batteries, and calcium ion secondary batteries, and capacitors such as lithium ion capacitors. The term "main resin" refers to the resin material that makes up the largest weight percentage of the resin materials that make up the resin material. Examples of "thermoplastic main resins having a first glass transition temperature Tg1 of 70°C or higher" include thermoplastic resins such as polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polytetrafluoroethylene (PTFE), and perfluoroalkoxyalkane (PFA), all of which have a first glass transition temperature Tg1 of 70°C or higher.

[0016] Examples of "thermoplastic elastomers" include thermoplastic polyurethane elastomers (TPUs) obtained from diisocyanates such as 4,4'-diphenylmethane diisocyanate (MDI) and high molecular weight diols. Examples of high molecular weight diols include polyester diols (PES), polyether diols (PET), polycaprolactone diols (PCL), and polycarbonate diols (PCD). The elastomers may have two glass transition temperatures, Tg2 and Tg3, or may be a mixture of an elastomer with only the second glass transition temperature, Tg2, and an elastomer with only the third glass transition temperature, Tg3.

[0017] Examples of the "filler" include glass fillers made of alkali glass, E-glass, etc., alumina fillers made of alumina, potassium titanate fillers made of potassium titanate, etc. The shape of the "filler" may be, for example, spherical, plate-like, fibrous, or needle-like. The resin material may contain materials other than the above-mentioned main resin, elastomer, and filler.

[0018] The first glass transition temperature Tg1 is preferably 150° C. or lower (70≦Tg1≦150). The third glass transition temperature Tg3 is preferably −140° C. or higher (−140≦Tg3≦−40).

[0019] To more appropriately prevent cracks from occurring in the resin member, it is preferable to set the linear expansion coefficient α3 of the resin material close to the linear expansion coefficient α1 of the metal constituting the case member and the linear expansion coefficient α2 of the metal constituting the terminal member. Specifically, the linear expansion coefficient α3 of the resin material is set to α1±0.8×10 with respect to the linear expansion coefficient α1 of the metal constituting the case member and the linear expansion coefficient α2 of the metal constituting the terminal member. -5 (1 / K), and α2±0.8×10 -5 It is preferable to set it within the range of (1 / K).

[0020] (2) In the electricity storage device according to (1), the third glass transition temperature Tg3 may be −60° C. or lower (Tg3≦−60).

[0021] In order to ensure the weather resistance of an electricity storage device, the device may be subjected to a thermal cycling test (upper limit temperature 65 to 90°C, lower limit temperature -40 to -20°C). It has been found that when such a thermal cycling test is performed, cracks may occur in the resin member near the boundary with the terminal member, and the cracks may further progress, causing the seal between the terminal member and the resin member to break down. When the power storage device is cooled below room temperature, the difference in thermal expansion between the case and terminal members and the resin member increases, increasing the stress on the resin member, making the relationship with the lower limit temperature particularly important. When the resin member reaches the lower limit temperature (-40 to -20°C) in a thermal cycle test, if the third glass transition temperature Tg3 of the elastomer is higher than or close to this lower limit temperature, the entire elastomer enters a hard glass state or a hard state that has not yet reached glass transition. As a result, the resin member (resin material) also becomes hard and elastic, and the difference in thermal expansion between the case and terminal members and the resin member places a large stress on the resin member, which is thought to make the resin member more susceptible to cracking.

[0022] In contrast, in the above-described electricity storage device, the third glass transition temperature Tg3 is set to Tg3≦−60°C, which is sufficiently lower than the lower limit temperature (−40 to −20°C). Therefore, the elastomer maintains a suitable softness even at the lower limit temperature, so that the stress reduction effect of the elastomer is maintained and cracks can be suppressed from occurring in the resin member. As a result, even when the electricity storage device is subjected to a thermal cycle test at a lower limit temperature of about −40 to −20°C, the sealing performance between the terminal member and the resin member can be maintained well.

[0023] (3) In the energy storage device described in (1) or (2), the terminal member may have a terminal seal portion to which the resin member is hermetically joined, on its surface, a forest of terminal nanopillars with a height of 50 nm or more, which are formed by particles of 100 nm or less in diameter derived from the metal constituting the terminal member being linked in a string-like manner to form pillars, and the resin material is filled between the forest of terminal nanopillars, making the resin member an energy storage device in which the resin member is hermetically joined to the terminal seal portion.

[0024] In the above-mentioned electricity storage device, the above-mentioned terminal nanopillars stand in rows on the surface of the terminal seal portion of the terminal member, and a resin material is filled between these terminal nanopillars to airtightly bond the resin member to the terminal seal portion. This increases the bonding strength between the terminal seal portion of the terminal member and the resin member, and makes it possible to maintain good sealing performance between the terminal member and the resin member.

[0025] In addition, examples of particles derived from the metal that constitutes the terminal member and that constitute the terminal nanopillar include particles made of the above metals, particles made of oxides of the above metals, and particles made of the above metals and oxides of the above metals.

[0026] (4) Still another aspect is a connector comprising a case member having an insertion hole, a terminal member inserted into the insertion hole of the case member, and an insert-molded resin member that hermetically joins the case member and the terminal member while insulating them and fixing the terminal member to the case member, wherein the resin member is made of a resin material containing a thermoplastic main resin having a first glass transition temperature Tg1 (Tg1≧70) of 70°C or higher, a thermoplastic elastomer, and a filler, and the elastomer has a second glass transition temperature Tg2 (−10≦Tg and a third glass transition temperature Tg3 (Tg3≦−40) of −40° C. or lower, the method including an insert molding step of insert-molding the resin member with the terminal members inserted into the insertion holes of the case member, wherein the insert molding step molds the resin member using the resin material including the main resin having the first glass transition temperature Tg1, the elastomer having the second glass transition temperature Tg2 and the third glass transition temperature Tg3, and the filler.

[0027] In the manufacturing method of the above-mentioned electricity storage device, a resin material containing the above-mentioned main resin, elastomer, and filler is used to mold the resin member in the insert molding process, so that it is possible to manufacture an electricity storage device in which cracks are suppressed from occurring in the resin member when the electricity storage device is placed at room temperature (25°C).

[0028] (5) A method for manufacturing an electric storage device according to (4), wherein the terminal member has a terminal seal portion to which the resin member is hermetically joined, the terminal seal portion having a forest of terminal nanopillars with a height of 50 nm or more, the terminal nanopillars being formed by a string of particles with a diameter of 100 nm or less derived from the metal constituting the terminal member, and the resin member is hermetically joined to the terminal seal portion with the resin material filled between the forest of terminal nanopillars; the resin member is hermetically joined to the terminal seal portion; and the method may further include a terminal nanopillar formation step, prior to the insert molding step, of irradiating the terminal seal portion of the terminal member with a pulsed laser beam while shifting the irradiation position, to form the forest of terminal nanopillars in the terminal seal portion; and the insert molding step may be a method for manufacturing an electric storage device in which the resin member is molded while filling the resin material between the forest of terminal nanopillars in the terminal seal portion.

[0029] In the above-described method for manufacturing an electricity storage device, the terminal nanopillars are formed on the surface of the terminal seal portion by irradiating the surface with laser light as described above in the terminal nanopillar formation step, so that the terminal nanopillars can be easily formed on the terminal seal portion. Furthermore, the resin member is molded while filling the spaces between the terminal nanopillars with resin material in the insert molding step, so that the bonding strength between the terminal seal portion of the terminal member and the resin member can be increased and good sealing performance between the terminal member and the resin member can be maintained. [Brief explanation of the drawings]

[0030] [Figure 1] FIG. 1 is a perspective view of a battery according to an embodiment. [Figure 2] 1 is a partially cutaway cross-sectional view of a battery according to an embodiment, taken along the battery height direction and the battery width direction. [Figure 3] 1A and 1B are enlarged cross-sectional views of the vicinity of the terminal member and the resin member of a battery according to an embodiment, where (a) is an enlarged cross-sectional view along the battery height direction and the battery width direction, and (b) is an enlarged cross-sectional view along the battery height direction and the battery thickness direction. [Figure 4] FIG. 2 is a partially enlarged cross-sectional view of the vicinity of the surface of a terminal seal portion (lid seal portion) in a battery according to an embodiment. [Figure 5]10 is an explanatory diagram showing a cross section of a resin material, relating to a method for measuring the linear expansion coefficient α3 of the resin material. FIG. [Figure 6] 3 is a flowchart of a method for manufacturing a battery according to an embodiment. [Figure 7] FIG. 2 is an explanatory diagram showing a terminal nanopillar forming step (lid nanopillar forming step) in the battery manufacturing method according to the embodiment. [Figure 8] 10A and 10B are explanatory diagrams of the insert molding process in the manufacturing method of the battery according to the embodiment, where FIG. 10A shows the state in which the terminal member is inserted into the insertion hole of the case lid member, and FIG. 10B shows the state in which the resin member is molded. [Figure 9] 10 is a graph showing the relationship between the number of thermal cycles in a thermal cycle test and the length of cracks generated in the resin member for the lid assemblies according to the example and comparative examples 1 and 2. DETAILED DESCRIPTION OF THE INVENTION

[0031] 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 partially cutaway cross-sectional view of the battery 1. Fig. 3 shows a partially enlarged cross-sectional view of the vicinity of terminal members 50, 60 and resin members 70, 80. Fig. 4 shows a partially enlarged cross-sectional view of the vicinity of surfaces 52m, 62m of terminal seal portions 52, 62. In the following description, the battery height direction AH, battery width direction BH, and battery thickness direction CH of battery 1 will be defined as the directions shown in Figs. 1 and 2. The battery 1 is a prismatic (rectangular) sealed lithium-ion secondary battery that can be installed in vehicles such as hybrid cars, plug-in hybrid cars, and electric cars.

[0032] The battery 1 is composed of a case 10, an electrode assembly 40 housed in the case 10, a positive electrode terminal member 50 fixed to the case 10 via a resin member 70, and a negative electrode terminal member 60 fixed to the case 10 via a resin member 80. The electrode assembly 40 is covered in a bag-shaped insulating holder 7 made of insulating film within the case 10. An electrolyte 5 is also housed within the case 10, a portion of which is impregnated into the electrode assembly 40 and the remainder of which is pooled on the bottom wall of the case 10.

[0033] The case 10 is a rectangular parallelepiped 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, which houses the electrode assembly 40 inside, and a rectangular plate-shaped case lid member 30 which closes the opening 20c of the case body member 20. In this embodiment, the case lid member 30 corresponds to the aforementioned "case member." The opening 20c of the case body member 20 and the peripheral edge 30f of the case lid member 30 are hermetically welded all around. Case lid member 30 of case 10 is provided with a safety valve 11 that ruptures and opens when the internal pressure of case 10 exceeds the valve opening pressure. Case lid member 30 is also provided with a liquid inlet hole 30k that penetrates case lid member 30, and this liquid inlet hole 30k is airtightly sealed with a disk-shaped sealing member 12 made of aluminum.

[0034] The electrode assembly 40 housed in the case 10 is a rectangular parallelepiped stacked type, in which a plurality of positive electrode plates 41 and a plurality of negative electrode plates 42 are alternately stacked in the battery thickness direction CH with separators 43 made of porous resin films sandwiched between them. The positive electrode plates 41, negative electrode plates 42, and separators 43 are each rectangular and extend in the battery height direction AH and battery width direction BH. The positive electrode plate 41 comprises a positive electrode current collector foil made of aluminum foil and a positive electrode active material layer containing positive electrode active material particles formed on each of the two main surfaces of the positive electrode current collector foil. A portion of the positive electrode current collector foil extends to one side BH1 in the battery width direction BH, forming an exposed positive electrode foil portion on both sides of the foil without the positive electrode active material layer. The exposed positive electrode foil portions of the positive electrode plates 41 overlap in the foil thickness direction to form a positive electrode current collector 40c. The positive electrode current collector 40c is electrically connected to a terminal member 50, which will be described later.

[0035] The negative electrode plate 42 comprises a negative electrode current collector foil made of copper foil and a negative electrode active material layer containing negative electrode active material particles formed on each of the two main surfaces of the negative electrode current collector foil. A portion of the negative electrode current collector foil extends to the other side BH2 in the battery width direction BH, forming an exposed negative electrode foil portion on both sides of the negative electrode current collector foil, free of the negative electrode active material layer. The exposed negative electrode foil portions of the negative electrode plates 42 overlap in the foil thickness direction to form a negative electrode current collector 40d. The negative electrode current collector 40d is electrically connected to a terminal member 60, which will be described later.

[0036] Rectangular insertion holes 30h1 and 30h2 are provided in the case lid member 30 near the ends on one side BH1 and the other side BH2 in the battery width direction BH, respectively, penetrating the case lid member 30. A positive electrode terminal member 50 made of aluminum is inserted into one of the insertion holes 30h1, and the terminal member 50 is fixed to the case lid member 30 while being insulated from the case lid member 30 via a resin member 70. A negative electrode terminal member 60 made of copper is inserted into the other insertion hole 30h2, and the terminal member 60 is fixed to the case lid member 30 while being insulated from the case lid member 30 via a resin member 80.

[0037] The terminal members 50, 60 (see Fig. 3 in addition to Figs. 1 and 2) are made by pressing metal plates (aluminum plate for the positive electrode and copper plate for the negative electrode) and consist of a rectangular plate-shaped terminal outer portion 51, 61 located outside the case lid member 30 (upper side AH1 in the battery height direction AH) and extending in the battery width direction BH and battery thickness direction CH, a terminal inner portion 53, 63 located inside the case lid member 30 (lower side AH2 in the battery height direction AH) and extending in the battery height direction AH, and a terminal seal portion 52, 62 connected to the terminal outer portion 51, 61 and the terminal inner portion 53, 63 via the insertion hole 30h1. The terminal seal portion 52, 62 bends at an end of the terminal outer portion 51, 61 on one side CH1 in the battery thickness direction CH and extends to the lower side AH2, penetrating resin members 70, 80 (described later) in the battery height direction AH. The positive electrode terminal inner part 53 is welded to the positive electrode current collector 40c of the electrode body 40 at the tip of the lower side AH2, and is electrically connected to the positive electrode current collector 40c. The negative electrode terminal inner part 63 is welded to the negative electrode current collector 40d of the electrode body 40 at the tip of the lower side AH2, and is electrically connected to the negative electrode current collector 40d.

[0038] The surfaces 51m, 61m of the terminal outer parts 51, 61 have rectangular top surfaces 51ma, 61ma facing the upper side AH1, rectangular inner side surfaces 51mb, 61mb facing the lower side AH2, and end surfaces 51mc, 61mc connecting these, and of these, the inner side surfaces 51mb, 51mb and the end surfaces 51mc, 61mc are joined to the resin members 70, 80. However, in this embodiment, terminal nano-pillars, which will be described later, are not formed on these inner side surfaces 51mb, 61mb and end surfaces 51mc, 61mc.

[0039] Meanwhile, resin members 70, 80 are airtightly joined to the terminal seal portions 52, 62. Specifically, the surfaces 52m, 62m of the terminal seal portions 52, 62 have first main surfaces 52ma, 62ma facing one side CH1 in the battery thickness direction CH, second main surfaces 52mb, 62mb facing the other side CH2 in the battery thickness direction CH, and a pair of end faces 52mc, 62mc connecting these. As shown in Fig. 4, the surfaces 52m, 62m are covered with a forest of terminal nanopillars 55, 65, each of which is formed by connecting together in a string of particles 55p, 65p derived from the metals (aluminum for the positive electrode and copper for the negative electrode) that make up the terminal members 50, 60.

[0040] Specifically, the positive electrode terminal nanopillars 55 are composed of particles 55p made of aluminum and aluminum oxide, and the negative electrode terminal nanopillars 65 are composed of particles 65p made of copper and copper oxide. The diameter Da of the particles 55p, 65p is 100 nm or less (in this embodiment, Da = approximately 30 nm), and the height ha of the terminal nanopillars 55, 65 is 50 nm or more (in this embodiment, ha = approximately 200 nm). Resin members 70, 80, which will be described later, are airtightly bonded to the terminal seal portions 52, 62 by filling the spaces between these standing terminal nanopillars 55, 65 with a resin material 75.

[0041] Resin members 70 and 80 are hermetically bonded to the lid seal portions 31 and 32 of the case lid member 30, which surround the insertion holes 30h1 and 30h2 (see FIG. 3). Specifically, the lid seal portions 31 and 32 have rectangular annular outer surfaces 31m and 32m facing outward (upper side AH1) and rectangular annular inner surfaces 31n and 32n facing inward (lower side AH2). Similar to the surface 52m of the positive electrode terminal seal portion 52 (see FIG. 4), these surfaces are covered with a forest of columnar lid nanopillars 35, each of which is made of aluminum and aluminum oxide particles 35p joined together in a string-like pattern. The diameter Da of the particles 35p is 100 nm or less (in this embodiment, approximately Da = 30 nm), and the height ha of the lid nanopillars 35 is 50 nm or more (in this embodiment, approximately ha = 200 nm). The resin members 70 and 80 described below are airtightly joined to the lid seal portions 31 and 32 by filling the spaces between the rows of lid nanopillars 35 with a resin material 75 .

[0042] Next, the resin members 70, 80 will be described (see FIGS. 1 to 4). The resin members 70, 80 are joined to the case lid member 30 and the terminal members 50, 60 while insulating the case lid member 30 from the terminal members 50, 60, and fix the terminal members 50, 60 to the case lid member 30. In detail, the resin members 70, 80 are airtightly joined to the terminal seal portions 52, 62 by filling a resin material 75, which will be described later, between the standing terminal nanopillars 55, 65 of the terminal seal portions 52, 62 of the terminal members 50, 60. The resin members 70, 80 are airtightly joined to the lid seal portions 31, 32 by filling a resin material 75, which will be described later, between the standing lid nanopillars 35 of the lid seal portions 31, 32 of the case lid member 30.

[0043] The resin members 70, 80 consist of a resin outer portion 71, 81 located on the outside (upper side AH1) of the case lid member 30, and a resin inner portion 72, 82 located on the inside (lower side AH2) of the case lid member 30 and within the insertion holes 30h1, 30h2, and connected to the resin outer portion 71, 81. Resin members 70, 80 are made of resin material 75 including thermoplastic main resin 76 having a first glass transition temperature Tg1, thermoplastic elastomer 77 having a second glass transition temperature Tg2 and a third glass transition temperature Tg3, and filler 78. The first glass transition temperature Tg1 of main resin 76 is 70°C or higher (Tg1≧70). The second glass transition temperature Tg2 of elastomer 77 is -10°C or higher and 20°C or lower (-10≦Tg2≦20), and the third glass transition temperature Tg3 is -40°C or lower (Tg3≦-40), or even -60°C or lower (Tg3≦-60).

[0044] Specifically, in this embodiment, the main resin 76 is polyphenylene sulfide (PPS) and has a first glass transition temperature Tg1 of 90°C. Elastomer 77 is a thermoplastic polyurethane elastomer (TPU) derived from 4,4'-diphenylmethane diisocyanate (MDI) and polyester diol (PES). This elastomer has two glass transition temperatures: the second glass transition temperature Tg2 = 10°C, and the third glass transition temperature Tg3 = -70°C. The filler 78 is a glass filler made of fibrous alkali glass (approximately 10 μm diameter×300 μm length). The weight ratio of the main resin 76, the elastomer 77, and the filler 78 is main resin:elastomer:filler=40:10:50.

[0045] Next, the linear expansion coefficient α3 of the resin material 75 will be described. The temperature range for each of the linear expansion coefficients α1, α21, α22, and α3 described below is -40 to 65°C. The linear expansion coefficient α1 of the aluminum constituting the case lid member 30 and the linear expansion coefficient α21 of the aluminum constituting the positive electrode terminal member 50 are α1±0.8×10 -5 (1 / K), and α21±0.8×10 -5 The linear expansion coefficient α3 of the resin material 75 forming the negative electrode resin member 80 is within the range of α1±0.8×10 (1 / K), while the linear expansion coefficient α1 of aluminum forming the case lid member 30 and the linear expansion coefficient α22 of copper forming the negative electrode terminal member 60 are within the range of α1±0.8×10 -5 (1 / K), and α22±0.8×10 -5 It is within the range of (1 / K).

[0046] Specifically, in this embodiment, the linear expansion coefficient α1 of the aluminum forming the case lid member 30 and the linear expansion coefficient α21 of the aluminum forming the positive electrode terminal member 50 are expressed as follows: α1=α21=2.4×10 -5 (1 / K). The linear expansion coefficient α22 of copper constituting the negative electrode terminal member 60 is α22=1.7×10 -5 On the other hand, the linear expansion coefficient α3 of the resin material 75 forming the resin members 70 and 80 is α3=2.3×10 -5(1 / K). Therefore, the relationship between these linear expansion coefficients α1, α21, α22, and α3 is α3 = α1 - 0.1 × 10 -5 (1 / K), α3=α21-0.1×10 -5 (1 / K), α3=α22+0.6×10 -5 (1 / K), and the aforementioned α3 ​​= α1 ± 0.8 × 10 -5 (1 / K), α3=α21±0.8×10 -5 (1 / K), α22±0.8×10 -5 The (1 / K) relationship is satisfied.

[0047] Here, a method for measuring the linear expansion coefficient α3 of the resin material 75 will be described (see FIG. 5). In this embodiment, the filler 78 contained in the resin material 75 is fibrous. Therefore, when the filler 78 dispersed in the resin material 75 is oriented, the linear expansion coefficient α3 of the resin material 75 has directionality. That is, when the filler 78 is oriented in the direction in which the surface of the resin material 75 expands, the first-direction linear expansion coefficient αM in the first direction MD (the direction extending in the left-right direction and in the direction perpendicular to the paper surface in FIG. 5) along the longitudinal direction of the filler 78 and the second-direction linear expansion coefficient αT in the second direction TD (the up-down direction in FIG. 5) perpendicular to the first direction MD have different magnitudes. Therefore, the first-direction linear expansion coefficient αM and the second-direction linear expansion coefficient αT are each calculated, and the average value is calculated to obtain the linear expansion coefficient α3 (α3=(αM+αT) / 2).

[0048] Specifically, the linear expansion coefficient αM in the first direction and the linear expansion coefficient αT in the second direction of the resin material 75 are determined by digital image correlation (DIC). First, a rectangular parallelepiped test piece of the resin material 75 in which the filler 78 is oriented in the direction in which the surface expands is prepared. This test piece is placed on a sample cooling and heating stage (e.g., Japan High-Tech Corporation's Large Sample Cooling and Heating Stage 10083L for Microscopes) so that cross sections along the first direction MD and the second direction (see FIG. 5) are visible. Then, an initial image of the test piece's cross section is acquired at 25°C. The image is acquired using, for example, Keyence Corporation's Digital Microscope VHX-8000.

[0049] The test piece is then cooled to -40°C and then heated to 65°C, and cross-sectional images of the test piece are obtained at temperatures of -40°C, 0°C, 25°C, 50°C, and 65°C. The obtained images are then analyzed using a DIC system (e.g., GOM's ARAMIS DIC system) to determine the relationship between temperature x and strain y in the first direction MD, as an approximate line y = ax + b. The slope a of this line is defined as the linear expansion coefficient αM in the first direction MD. Similarly, the relationship between temperature x and strain y in the second direction TD is determined as an approximate line y = cx + d. The slope c of this line is defined as the linear expansion coefficient αT in the second direction TD. The average of these values ​​((αM + αT) / 2) is then calculated, and this is defined as the linear expansion coefficient α3.

[0050] In the battery 1 of this embodiment, of the resin material 75 constituting the resin members 70, 80, the main resin 76 has a first glass transition temperature Tg1 of 70°C or higher, while the elastomer 77 has a second glass transition temperature Tg2 of -10°C or higher and 20°C or lower, and a third glass transition temperature Tg3 of -40°C or lower. This can prevent cracks from occurring in the resin members 70, 80 when the battery 1 is placed at room temperature (25°C). The reason for this will be explained in the "Test Results" section below.

[0051] Furthermore, in this embodiment, the third glass transition temperature Tg3 is set to Tg3≦−60°C, which is sufficiently lower than the lower limit temperature (−40 to −20°C) of the thermal cycling test. Therefore, the elastomer 77 maintains a moderate softness even at the lower limit temperature, thereby maintaining the stress reduction effect of the elastomer 77 and suppressing cracks from occurring in the resin members 70, 80. As a result, even when the battery 1 is subjected to a thermal cycling test at a lower limit temperature of approximately −40 to −20°C, the sealing performance between the terminal members 50, 60 and the resin members 70, 80 can be maintained satisfactorily. The thermal cycling test will be described later.

[0052] Furthermore, in this embodiment, terminal nanopillars 55, 65 stand in rows on the surfaces 52m, 62m of the terminal seal portions 52, 62 of the terminal members 50, 60, and a resin material 75 is filled between these terminal nanopillars 55, 65, airtightly bonding the resin members 70, 80 to the terminal seal portions 52, 62. This increases the bonding strength between the terminal seal portions 52, 62 of the terminal members 50, 60 and the resin members 70, 80, and makes it possible to maintain good sealing performance between the terminal members 50, 60 and the resin members 70, 80.

[0053] Next, a manufacturing method of the battery 1 will be described (see FIGS. 6 to 8). First, a pre-roughening case lid member (case member) 30Z is prepared. The pre-roughening case lid member 30Z is obtained by punching an aluminum plate into a predetermined shape and forming the liquid injection hole 30k, the insertion holes 30h1 and 30h2, and the safety valve 11. Pre-roughening terminal members 50Z and 60Z are also prepared. The pre-roughening positive electrode terminal member 50Z is obtained by punching an aluminum plate into a predetermined shape and bending it. The pre-roughening negative electrode terminal member 60Z is obtained by punching a copper plate into a predetermined shape and bending it.

[0054] Then, in the "terminal nanopillar formation step S1" (see FIG. 6), the terminal seal portions 52, 62 of the terminal members 50Z, 60Z are irradiated with pulsed laser light LC while shifting the irradiation position (see FIG. 7), to form a forest of terminal nanopillars 55, 65 on the surfaces 52m, 62m of the terminal seal portions 52, 62. As described above (also see FIG. 4), the terminal nanopillars 55, 65 are formed by particles 55p, 65p linked together in a string to form a pillar shape.

[0055] In this embodiment, the conditions for irradiating the positive electrode laser were a wavelength of 1064 nm, a peak power of 5 kW, a pulse width of 150 ns, a pitch (pb) of 75 μm, and a spot diameter (Db) of 80 μm. The conditions for irradiating the negative electrode laser were a wavelength of 1064 nm, a peak power of 20 kW, a pulse width of 50 ns, a pitch (pb) of 60 μm, and a spot diameter (Db) of 75 μm. In the circular areas of the terminal seal portions 52 and 62 irradiated with the laser light LC in a plan view, the metal (aluminum for the positive electrode and copper for the negative electrode) near the surfaces 52 m and 62 m melts and turns into vapor. Then, as the temperature of the vapor decreases, the metal turns into particles 55 p and 65 p (aluminum and aluminum oxide particles 55 p for the positive electrode and copper and copper oxide particles 65 p for the negative electrode) and deposits on the surfaces 52 m and 62 m of the terminal seal portions 52 and 62. By irradiating the terminal seal portions 52, 62 with the laser light LC while shifting the irradiation position, the particles 55p, 65p are deposited in a string and bonded to form columns, thereby forming a forest of terminal nano-pillars 55, 65.

[0056] Separately, in the "lid nanopillar formation step S2" (see FIG. 6), pulsed laser light LC is irradiated onto the lid seal portions 31, 32 of the case lid member 30Z while shifting the irradiation position (see FIG. 7), forming forests of lid nanopillars 35 on the outer surfaces 31m, 32m and inner surfaces 31n, 32n of the lid seal portions 31, 32. As described above (see also FIG. 4), the lid nanopillars 35 are formed by particles 35p made of aluminum and aluminum oxide linked together in a string-like pattern to form columns. In this embodiment, the laser irradiation conditions were the same as those used to form the terminal nanopillars 55 on the positive electrode terminal seal portion 52 in the terminal nanopillar formation step S1.

[0057] Next, in the "insert molding process S3" (see FIG. 6), with the terminal members 50 and 60 inserted into the insertion holes 30h1 and 30h2 of the case lid member 30, respectively, resin members 70 and 80 are insert molded using a resin material 75 containing a main resin 76 having the aforementioned first glass transition temperature Tg1, an elastomer 77 having a second glass transition temperature Tg2 and a third glass transition temperature Tg3, and a filler 78 (see FIG. 8).

[0058] Specifically, the insert molding step S3 is performed using a molding die (not shown) having upper and lower molds. First, the case lid member 30 is placed in a predetermined position in the lower mold, and then the terminal members 50 and 60 are inserted into the insertion holes 30h1 and 30h2 of the case lid member 30, respectively (see FIG. 8(a)). After that, the upper mold is moved toward the lower mold to close the molding die. Next, molten resin material 75 is injected into each of the two cavities of the molding die. At this time, the resin material 75 is filled also between the terminal nanopillars 55 and 65 of the terminal seal portions 52 and 62 and between the lid nanopillars 35 of the lid seal portions 31 and 32, thereby molding resin members 70 and 80 that are airtightly bonded to the terminal seal portions 52 and 62 and the lid seal portions 31 and 32, respectively (see FIG. 8(b)). Thereafter, the lid assembly 15 in which the terminal members 50, 60 are fixed to the case lid member 30 via the resin members 70, 80 is removed from the molding die.

[0059] Next, in the "electrode body connecting step S4" (see FIG. 6), an electrode body 40 is prepared by stacking a positive electrode plate 41, a negative electrode plate 42, and a separator 43, and the terminal inner portion 53 of the terminal member 50 of the lid assembly 15 is welded to the positive electrode current collecting portion 40c of the electrode body 40. Also, the terminal inner portion 63 of the terminal member 60 of the lid assembly 15 is welded to the negative electrode current collecting portion 40d of the electrode body 40. Thereafter, the electrode body 40 is wrapped in a bag-shaped insulating holder 7. Next, in the "electrode assembly accommodating / case forming process S5," a case body member 20 is prepared, 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 case lid member 30. The opening 20c of the case body member 20 and the peripheral edge portion 30f of the case lid member 30 are then laser-welded airtightly along the entire periphery to form the case 10 accommodating the electrode assembly 40 inside.

[0060] Next, in the "pouring and sealing step S6," the electrolyte 5 is poured into the case 10 through the pouring hole 30k, and the electrolyte 5 is impregnated into the electrode body 40. Thereafter, the pouring hole 30k is covered from the outside with a sealing member 12, and the sealing member 12 is laser-welded to the case 10 in an airtight manner. Next, in the "initial charging and aging step S7," a charging device (not shown) is connected to the battery 1, and the battery 1 is initially charged. After that, the initially charged battery 1 is left to stand for a predetermined time to age the battery 1. In this way, the battery 1 is completed.

[0061] As described above, in the manufacturing method of battery 1, in the insert molding process S3, the resin members 70, 80 are molded using a resin material 75 containing the aforementioned main resin 76, elastomer 77, and filler 78, so that it is possible to manufacture battery 1 in which cracks are suppressed from occurring in the resin members 70, 80 when the battery 1 is placed at room temperature (25°C). Furthermore, in the terminal nanopillar forming step S1, as described above, the terminal nanopillars 55, 65 are formed on the surfaces 52m, 62m of the terminal seal portions 52, 62 by irradiating them with laser light LC, so that the terminal nanopillars 55, 65 can be easily formed on the terminal seal portions 52, 62. Then, in the insert molding step S3, the resin members 70, 80 are molded while filling the spaces between the terminal nanopillars 55, 65 with resin material 75, so that the bonding strength between the terminal seal portions 52, 62 of the terminal members 50, 60 and the resin members 70, 80 is increased, and the sealing performance between the terminal members 50, 60 and the resin members 70, 80 can be maintained favorably.

[0062] (Test results) Next, the results of a test conducted to verify the effects of the present invention will be described (see FIG. 9). As an example, a lid assembly 15 (see FIG. 8(b)) according to the aforementioned embodiment was prepared. That is, the terminal nanopillar forming step S1, the lid nanopillar forming step S2, and the insert molding step S3 were performed to obtain a lid assembly 15 in which terminal members 50, 60 were fixed to a case lid member 30 via resin members 70, 80. The resin material 75 used in the insert molding included a main resin 76 having a first glass transition temperature Tg1 (= 90°C), an elastomer 77 having a second glass transition temperature Tg2 (= 10°C) and a third glass transition temperature Tg3 (= -70°C), and a filler 78. In this example, the first glass transition temperature Tg1 (=90°C) satisfies Tg1≧70(°C), the second glass transition temperature Tg2 (=10°C) satisfies −10≦Tg2≦20(°C), and the third glass transition temperature Tg3 (=−70°C) satisfies Tg3≦−40(°C).

[0063] On the other hand, in Comparative Example 1, a resin material 75 was prepared, including a main resin 76 having a first glass transition temperature Tg1 (=90°C), an elastomer 77 having a second glass transition temperature Tg2 (=-60°C) and a third glass transition temperature Tg3 (=-80°C), and a filler 78. Using this resin material 75, the lid assembly 15 was formed in the same manner as in the Example, except for the above. In Comparative Example 1, the first glass transition temperature Tg1 (=90°C) satisfies Tg1≧70(°C), and the third glass transition temperature Tg3 (=-80°C) satisfies Tg3≦−40(°C), but the second glass transition temperature Tg2 (=-60°C) does not satisfy −10≦Tg2≦20(°C).

[0064] Furthermore, as Comparative Example 2, a resin material 75 was prepared that included a main resin 76 having a first glass transition temperature Tg1 (=90°C), an elastomer 77 having only a second glass transition temperature Tg2 (=-10°C), and a filler 78, and the lid assembly 15 described above was formed using this material in the same manner as in the Example, except for the above. In Comparative Example 2, the first glass transition temperature Tg1 (=90°C) satisfies Tg1≧70(°C), and the second glass transition temperature Tg2 (=-10°C) satisfies -10≦Tg2≦20(°C), but because there is no third glass transition temperature Tg3, Tg3≦-40(°C) is not satisfied.

[0065] The lid assemblies 15 of the example and comparative examples were then maintained at room temperature (25°C) (with the resin members 70, 80 at room temperature), and the lengths of cracks occurring in the positive electrode resin member 70 near the boundary with the terminal member 50 and the negative electrode resin member 80 near the boundary with the terminal member 60 were measured. As a result, in the example, no cracks occurred in either of the resin members 70, 80. In FIG. 9, the crack length is shown as 0.0 mm when the number of thermal cycles n=0. Meanwhile, in Comparative Example 1, 0.5 mm cracks occurred in both of the resin members 70, 80. Furthermore, in Comparative Example 2, 1.0 mm cracks occurred in both of the resin members 70, 80.

[0066] Next, these lid assemblies 15 were subjected to a thermal cycle test in a temperature range from a lower limit of -40°C to an upper limit of 65°C, taking into consideration the operating temperature conditions of the battery 1. Specifically, using a liquid bath tester, the lid assemblies were immersed in a liquid bath at -40°C for 3 minutes, followed by immersion in a liquid bath at 65°C for 3 minutes, with this cycle consisting of cooling and heating, and this cycle was repeated 4,000 times. Then, after 1,000, 2,000, 3,000, and 4,000 cooling and heating cycles, the lengths of cracks occurring in the resin members 70 and 80 were measured as described above. The results are summarized in Figure 9. In this test, there was no difference in the size of the cracks between the positive electrode resin member 70 and the negative electrode resin member 80, so the resin members 70 and 80 are shown without distinction in Fig. 9. In addition, since the seal length between the terminal members 50, 60 and the resin members 70, 80 is 2.5 mm, the maximum crack length in this test was 2.5 mm (when the crack length is 2.5 mm, the seal between the terminal members 50, 60 and the resin members 70, 80 is destroyed).

[0067] 9, in the examples, no cracks occurred in the resin members 70, 80 even after the thermal cycling test. On the other hand, in comparative example 1, the cracks grew as the number of thermal cycles n increased, and at n=3000, the cracks reached a length of 2.5 mm, destroying the seal between the terminal members 50, 60 and the resin members 70, 80. In comparative example 2, the cracks grew as the number of thermal cycles n increased, and at n=4000, the cracks reached a length of 2.5 mm, destroying the seal between the terminal members 50, 60 and the resin members 70, 80.

[0068] The reason for this result is believed to be as follows: In all of the example and comparative examples 1 and 2, the first glass transition temperature Tg1 (=90°C) of main resin 76 contained in resin material 75 is sufficiently higher than room temperature, so that main resin 76 is in a glassy state at room temperature, and is hard and has high strength but low toughness. In Comparative Example 2, the elastomer 77 has only a second glass transition temperature Tg2, and this second glass transition temperature Tg2 (=-10°C) is within a range of -10°C or higher (higher than room temperature or slightly lower than room temperature). In such a case, when the temperature of the resin members 70, 80 is at room temperature, the elastomer 77 is in a hard state, even if not in a glassy state. As a result, the resin members 70, 80 become hard and elastic. Due to the difference in thermal expansion between the case lid member 30 and the terminal members 50, 60 and the resin members 70, 80, large stress is applied to the resin members 70, 80, causing cracks in the resin members 70, 80. Furthermore, it is believed that the cracks propagated as the temperature of the lid assembly 15 was repeatedly changed during the thermal cycle test, destroying the seal between the terminal members 50, 60 and the resin members 70, 80.

[0069] In Comparative Example 1, the elastomer 77 has a second glass transition temperature Tg2 (-60°C) and a third glass transition temperature Tg3 (-80°C), both of which are sufficiently lower than room temperature (-40°C or lower). In this case, the elastomer 77 is in a sufficiently soft, rubbery, elastic state when the resin members 70, 80 are at room temperature. Therefore, if there is a difference in thermal expansion between the case lid member 30 and the terminal members 50, 60 and the resin members 70, 80, the elastomer 77 is too soft and easily deforms, preventing sufficient stress dispersion. This results in a large stress being applied to the main resin 76 of the resin members 70, 80, causing cracks in the resin members 70, 80. Furthermore, repeated temperature fluctuations in the thermal cycle test of the lid assembly 15 likely propagate these cracks, destroying the seal between the terminal members 50, 60 and the resin members 70, 80.

[0070] In contrast, in the working example, elastomer 77 has a second glass transition temperature Tg2 (= 10°C) that is slightly lower than room temperature (-10 to 20°C) and a third glass transition temperature Tg3 (= -70°C) that is sufficiently lower than room temperature (-40°C or lower). Therefore, when the temperatures of resin members 70, 80 are set to room temperature, part of elastomer 77 is hard because the second glass transition temperature Tg2 (= 10°C) is close to room temperature, but the remainder of elastomer 77 remains sufficiently soft because the third glass transition temperature Tg3 (= -70°C) is sufficiently lower than room temperature, and it is considered that elastomer 77 as a whole has an appropriate hardness (appropriate softness). As a result, even if there is a difference in thermal expansion between the case cover member 30 and the terminal members 50, 60 and the resin members 70, 80, the elastomer 77, which has a moderate hardness, deforms and distributes the stress, reducing the stress applied to the main resin 76 of the resin members 70, 80 and preventing cracks from occurring in the resin members 70, 80.

[0071] Furthermore, in the embodiment, the third glass transition temperature Tg3 (=-70°C) of the elastomer 77 is set to Tg3≦-60 (°C), which is sufficiently lower than the lower limit temperature (-40°C). Therefore, the elastomer 77 maintains a moderate softness even at the lower limit temperature (-40°C), thereby maintaining the stress reduction effect of the elastomer 77 and preventing cracks from occurring in the resin members 70, 80. This is thought to have enabled the sealing performance between the terminal members 50, 60 and the resin members 70, 80 to be maintained satisfactorily even when a thermal cycling test was performed.

[0072] 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]

[0073] 1. Battery (energy storage device) 10 cases 30 Case cover member (case member) 30h1, 30h2 insertion holes 40 Electrode body 50,60 Terminal material 52,62 Terminal seal 52m, 62m (Terminal seal part) surface 55,65 terminal nano pillar 55p,65p particles 70,80 Resin material 75 Resin material 76 Main Resin 77 Elastomer 78 Filler α Linear expansion coefficient LC laser light S1 Terminal nanopillar formation process S3 Insert molding process

Claims

1. a case member having an insertion hole; a terminal member inserted into the insertion hole of the case member; an insert-molded resin member that hermetically joins the case member and the terminal members while insulating them from each other and fixes the terminal members to the case member; The resin member is made of a resin material containing a thermoplastic main resin having a first glass transition temperature Tg1 of 70°C or higher (Tg1≧70), a thermoplastic elastomer, and a filler. An electricity storage device, The elastomer is It has a second glass transition temperature Tg2 of -10°C or higher and 20°C or lower (-10≦Tg2≦20) and a third glass transition temperature Tg3 of -40°C or lower (Tg3≦-40). Energy storage device.

2. The electricity storage device according to claim 1 , The third glass transition temperature Tg3 is −60° C. or lower (Tg3≦−60° C.). Energy storage device.

3. The electricity storage device according to claim 1 or 2, The terminal seal portion of the terminal member to which the resin member is airtightly joined is On the surface of the terminal member, there are forests of terminal nanopillars each having a height of 50 nm or more, each of which is formed by connecting in a string of beads particles each having a diameter of 100 nm or less derived from the metal constituting the terminal member, The resin member is The resin material is filled between the standing terminal nano-pillars and is airtightly bonded to the terminal seal portion. Energy storage device.

4. a case member having an insertion hole; a terminal member inserted into the insertion hole of the case member; an insert-molded resin member that hermetically joins the case member and the terminal members while insulating them from each other and fixes the terminal members to the case member; the resin member is made of a resin material including a thermoplastic main resin having a first glass transition temperature Tg1 of 70°C or higher (Tg1≧70), a thermoplastic elastomer, and a filler; The elastomer has a second glass transition temperature Tg2 of -10°C or higher and 20°C or lower (-10≦Tg2≦20) and a third glass transition temperature Tg3 of -40°C or lower (Tg3≦-40). A method for manufacturing an electricity storage device, comprising: an insert molding step of insert-molding the resin member in a state where the terminal member is inserted into the insertion hole of the case member, The insert molding process includes: The resin member is molded using the resin material including the main resin having the first glass transition temperature Tg1, the elastomer having the second glass transition temperature Tg2 and the third glass transition temperature Tg3, and the filler. A method for manufacturing an electricity storage device.

5. A method for manufacturing the electricity storage device according to claim 4, a terminal seal portion of the terminal member to which the resin member is airtightly joined has a surface on which terminal nano-pillars with a height of 50 nm or more stand in rows, the pillars being formed by particles with a diameter of 100 nm or less derived from a metal constituting the terminal member and linked together in a string-like pattern; the resin member is configured such that the resin material is filled between the standing terminal nano-pillars and is airtightly joined to the terminal seal portion, a terminal nanopillar forming step of irradiating the terminal seal portion of the terminal member with a pulsed laser beam while shifting the irradiation position, prior to the insert molding step, to form a forest of the terminal nanopillars on the terminal seal portion, The insert molding process includes: The resin member is molded while filling the spaces between the terminal nano-pillars of the terminal seal portion with the resin material. A method for manufacturing an electricity storage device.

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