Power storage device

Abstract

To provide a power storage device improved in heat conduction from an electrode body to a case.SOLUTION: A power storage device 1 includes heat transfer and insulating materials 71, 72 that are interposed between a case 10 and an electrode body 40, and that adhere closely to pressing wall portions 17, 18 and adhere closely to an insulating holder 60 covering the electrode body 40 or directly to the electrode body 40. Pressing inner surfaces 21, 22 of the pressing wall portions 17, 18 include area increased portions 23, 24. A plurality of protrusions 25 of the area increased portions 23, 24 bite into the heat transfer and insulating materials 71, 72 and the heat transfer and insulating materials 71, 72 bite into a plurality of recesses 26 of the area increased portions 23, 24, so that the heat transfer and insulating materials 71, 72 and the area increased portions 23, 24 increase a contact area Sc between the pressing wall portions 17, 18 and the heat transfer and insulating materials 71, 72.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an electricity storage device including an electrode assembly and a metal case that houses and presses the electrode assembly. [Background technology]

[0002] As an electricity storage device, a prismatic battery is known in which a flat electrode body is wrapped in an insulating holder made of insulating film and housed in a rectangular box-shaped case. Among such batteries, there is one in which a pair of main walls of the case facing each other in the thickness direction of the battery sandwich and press the electrode body in the thickness direction of the battery. Related prior art includes, for example, Patent Document 1 (see Figures 1, 2, 5, etc. of Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-141192 Summary of the Invention [Problem to be solved by the invention]

[0004] In order to further improve the insulation between the case and the electrode body in the above-mentioned battery, the inventor considered interposing an insulating resin plate made of an insulating resin material between the main wall portion of the case and the insulating holder covering the electrode body. However, in this battery, the heat conduction from the insulating resin plate to the main wall of the case is poor, making it difficult to efficiently transfer the heat generated in the electrode assembly to the case through the insulating holder and the insulating resin plate and dissipate it from the case to the outside of the battery. This is because the inner surface of the main wall of the case is not strictly flat, and the case is hard, so a gap is created between the inner surface of the main wall and the insulating resin plate. It has been found that this gap reduces the heat conduction from the insulating resin plate to the main wall via the inner surface, resulting in poor heat conduction from the electrode assembly to the case.

[0005] The present invention has been made in view of the above-mentioned current situation, and provides an electricity storage device in which heat conduction from the electrode body to the case is improved. [Means for solving the problem]

[0006] (1) One aspect of the present invention for solving the above problem is an electricity storage device comprising an electrode body and a metal case that houses the electrode body, the case having a pressing wall that presses the electrode body, and further comprising an insulating and thermally conductive heat transfer insulating material that is interposed between the pressing wall and the electrode body and in close contact with the pressing wall, and that is in close contact with an insulating holder made of an insulating film that covers the electrode body, or in direct contact with the electrode body, the pressing wall having a pressing inner surface facing the inside of the pressing wall, and the pressing inner surface including an area increasing portion that has been subjected to an area increasing process to form a large number of protrusions and recesses to increase the surface area, and the heat transfer insulating material and the area increasing portion are configured such that the large number of protrusions of the area increasing portion bite into the heat transfer insulating material, and the heat transfer insulating material bites into the large number of recesses of the area increasing portion, thereby increasing the contact area between the pressing wall and the heat transfer insulating material.

[0007] In the above-mentioned electricity storage device, the above-mentioned area increasing portion including many protrusions and recesses is formed on the pressing inner surface of the pressing wall portion of the case, and the many protrusions of the area increasing portion are made to bite into the heat transfer insulating material, and the heat transfer insulating material is made to bite into the many recesses of the area increasing portion, thereby increasing the contact area between the pressing wall portion and the heat transfer insulating material. As a result, heat generated in the electrode body and transferred to the heat transfer insulating material can be efficiently transferred from the heat transfer insulating material to the pressing wall portion, thereby achieving good heat conduction from the electrode body to the case in an electricity storage device including a heat transfer insulating material.

[0008] 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 "electrode body" is not limited to singular, but may be plural. Specifically, the plurality of electrode bodies may be arranged in a row and connected to each other to form an electrode body group. Examples of "thermal insulating materials" include flexible thermal insulating sheets such as gel sheets that are both insulating and thermally conductive, and thermal insulating resin layers formed by applying and curing a paste-like resin material to the inner pressing surface, including the increased area portion, to form an integrated thermal insulating resin layer with the pressing wall portion. The thermal insulating material preferably has a thermal conductivity of 1.0 W / m K or higher, and more preferably 2.0 W / m K or higher.

[0009] Examples of "area increasing treatment" include physical area increasing treatment such as shot blasting, sand blasting, metal spraying, etc., chemical area increasing treatment such as anodic oxidation, chemical etching, etc., area increasing treatment to form nano-order convex and concave portions by irradiating with a pulsed laser, etc. Area increasing treatment may also be area increasing treatment to form a large number of convex and concave portions by pressing the case, or area increasing treatment to form a large number of convex and concave portions by using a casting mold when casting the case. The "increased area portion" may be formed on only a portion of the pressing inner surface, or may be formed on the entire pressing inner surface. Furthermore, convex portions and concave portions similar to the convex portions and concave portions of the increased area portion may be formed on the inside surface of the case in areas other than the pressing inner surface.

[0010] (2) Furthermore, in the energy storage device described in (1), the heat-transfer insulating material may be made of a resin material having insulating and thermal conductivity, and the area-increasing portion may be made of a forest of protrusions made of nanopillars with a height of 50 nm or more, each of which is formed by particles derived from the metal constituting the case being linked together in a string-like pattern to form a columnar shape, and the recesses may be formed between the forest of nanopillars.

[0011] In the above-described power storage device, the heat transfer insulating material is a heat transfer insulating material made of a resin material, and the area increase portion of the case is an area increase portion on the nano level (nano order) where the above-described nano pillars stand in rows. This allows the pressing wall portion of the case and the heat transfer insulating material to be in contact with each other over a particularly wide contact area, thereby further improving heat conduction from the heat transfer insulating material to the pressing wall portion.

[0012] (3) The electric storage device according to (1) or (2), further comprising: the case having a rectangular parallelepiped box shape, a rectangular first main wall portion, a rectangular second main wall portion facing the first main wall portion, and four rectangular side wall portions connecting the first main wall portion and the second main wall portion; the first main wall portion includes a first pressing wall portion that is the pressing wall portion; the second main wall portion includes a second pressing wall portion that is the pressing wall portion; the electric storage device further comprises a first heat transfer insulating material that is the heat transfer insulating material between the first pressing wall portion of the first main wall portion and the electrode body; The second heat transfer insulating material is provided between the second pressing wall portion and the electrode body, and the case has a bottomed, square cylindrical shape that forms the second main wall portion and the four side wall portions and has a rectangular opening, and has a case body member that houses the second heat transfer insulating material, the electrode body, and the first heat transfer insulating material in that order inside, and a rectangular case lid member that forms the first main wall portion and closes the opening of the case body member, and the opening of the case body member and the peripheral portion of the case lid member are preferably joined around their entire periphery to form an electricity storage device.

[0013] In the above-described power storage device, the opening of the case body member accommodating the first heat transfer insulator, the electrode assembly, and the second heat transfer insulator is joined to the peripheral edge of the case lid member along the entire periphery. This prevents damage to the protrusions and recesses in the area-increasing portions of each pressing wall member and to the heat transfer insulators that would occur if the first pressing wall member were to be laterally displaced along the surface between the first heat transfer insulator or the second pressing wall member is to be laterally displaced along the surface between the second pressing wall member and the second heat transfer insulator. This also ensures that the protrusions and recesses in the area-increasing portions and the heat transfer insulators are securely engaged with each other.

[0014] (4) Yet another aspect is a method for manufacturing an electric storage device as described in (3), which includes an arrangement step of accommodating the second heat transfer insulation material, the electrode body, and the first heat transfer insulation material in this order within the case body member and arranging the case lid member on the case body member; a case forming step of narrowing the gap between the first main wall portion formed by the case lid member and the second main wall portion of the case body member, and joining the opening of the case body member and the peripheral portion of the case lid member around the entire circumference while pressing the first heat transfer insulation material, the electrode body, and the second heat transfer insulation material; and a method for manufacturing an electric storage device.

[0015] In a typical prismatic battery, the case is composed of a case body member in the shape of a rectangular cylinder with a bottom, which forms the first main wall portion, the second main wall portion, and three side walls of the case, and a case lid member which forms one side wall portion. In a battery of this type, if the first and second thermally conductive insulating materials are disposed, it becomes difficult to manufacture the battery. This is because the gap between the first and second main wall portions of the case body member is narrower than the combined thickness of the first thermally conductive insulating material, the electrode body, and the second thermally conductive insulating material in order to press the electrode body in the assembled battery, making it difficult to insert the electrode body into the case body member. In contrast, in the method for manufacturing an electricity storage device, the electrode body can be easily accommodated in a case body member that is a rectangular cylindrical case with a bottom and that has a second main wall and four side walls. After that, the opening of the case body member is closed with a case lid member that forms the first main wall, and the opening of the case body member and the peripheral edge of the case lid member are joined, so the electricity storage device can be easily manufactured. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a perspective view of a battery according to an embodiment. [Figure 2] 1 is a partial cross-sectional view of a battery according to an embodiment, taken along the battery height direction and the battery width direction. [Figure 3] 1 is a cross-sectional view of a battery according to an embodiment taken along the battery height direction and the battery thickness direction. [Figure 4] FIG. 4 is an enlarged cross-sectional view showing a contact portion between a pressing wall portion of the case and a thermal insulating material in the embodiment. [Figure 5] 3 is a flowchart of a method for manufacturing a battery according to an embodiment. [Figure 6] 10 is an explanatory diagram showing a state in which the positive electrode current collector and the negative electrode current collector of the electrode body are welded to current collector members, respectively, in the manufacturing method of the battery according to the embodiment. FIG. [Figure 7] 10A and 10B are explanatory diagrams showing how a pulsed laser beam is scanned to form a plurality of bowl-shaped recesses and nano-columns standing tall in the bowl-shaped recesses on the pressing inner surface of the pressing wall portion, in relation to the battery manufacturing method according to the embodiment. [Figure 8] FIG. 10 is an explanatory diagram showing a manufacturing method of a battery according to an embodiment, in which a first heat-transfer insulating material is formed on a first pressing inner surface of a case lid member and a second heat-transfer insulating material is formed on a second pressing inner surface of a case body member. [Figure 9] FIG. 10 is an explanatory diagram showing a method for manufacturing a battery according to an embodiment, in which an electrode body is housed in a case body member, and positive and negative current collecting members connected to the electrode body are laser welded to positive and negative terminal members fixed to the case body member. [Figure 10] FIG. 10 is an explanatory diagram showing a method for manufacturing a battery according to an embodiment, in which a second heat-transfer insulating material, an electrode body, and a first heat-transfer insulating material are placed in this order inside a case body member, and a case lid member is placed on top of the case body member. [Figure 11] 10 is an explanatory diagram showing how the opening of the case body member and the peripheral edge of the case lid member are laser-welded together while the electrode body and the like are pressed, in relation to the manufacturing method of the battery according to the embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] An embodiment of the present invention will be described below with reference to the drawings. Fig. 1 shows a perspective view of a battery (electricity storage device) 1 of this embodiment, Fig. 2 shows a partial cross-sectional view of the battery 1 taken along the battery height direction AH and battery width direction BH, and Fig. 3 shows a cross-sectional view of the battery 1 taken along the battery height direction AH and battery thickness direction CH. Fig. 4 also shows an enlarged cross-sectional view of the contact portion between the pressing walls 17 and 18 of the case 10 and the thermal insulating materials 71 and 72. In the following description, the battery height direction AH, battery width direction BH, and battery thickness direction CH of the battery 1 are defined as the directions shown in Figs. 1 to 3.

[0018] Battery 1 is a rectangular (rectangular) sealed lithium ion secondary battery that is installed in vehicles such as hybrid cars, plug-in hybrid cars, and electric cars. Battery 1 is composed of a case 10, an electrode assembly 40 and an electrolyte 5 housed in the case 10, and positive and negative terminal members 50 each supported by the case 10. The electrode assembly 40 is covered by an insulating holder 60 within the case 10. In addition, a pair of thermal insulating materials (a first thermal insulating material 71 and a second thermal insulating material 72) are disposed between the case 10 and the insulating holder 60 that encases the electrode assembly 40.

[0019] The electrode assembly 40 is a rectangular parallelepiped laminated structure in which a plurality of rectangular positive electrode plates 41 and a plurality of rectangular negative electrode plates 42 are alternately stacked with rectangular separators 43 interposed between them, each separator being a porous resin film. The electrode assembly 40 is housed in the case 10 in a position in which the electrode assembly thickness direction DH is parallel to the battery thickness direction CH and is pressed in the electrode assembly thickness direction DH. That is, in the battery 1 of this embodiment, the first main wall portion 11 and the second main wall portion 12 of the case 10, which are elastically deformed, elastically press the electrode assembly 40 in the electrode assembly thickness direction DH.

[0020] On one side BH1 of the electrode body 40 in the battery width direction BH, the current collecting foil of each positive electrode plate 41 extends toward the one side BH1, and the current collecting foils overlap to form a positive electrode current collecting portion 40c. This positive electrode current collecting portion 40c is welded to a positive electrode current collecting member 45, which is further welded to a positive electrode terminal member 50. On the other side BH2 of the electrode body 40 in the battery width direction BH, the current collecting foil of each negative electrode plate 42 extends toward the other side BH2, and the current collecting foils overlap to form a negative electrode current collecting portion 40d. This negative electrode current collecting portion 40d is welded to a negative electrode current collecting member 45, which is further welded to a negative electrode terminal member 50.

[0021] The insulating holder 60 that covers the electrode body 40 is made by folding and partially welding an insulating film 61 cut to a predetermined shape into a cylindrical shape, and has openings on one side BH1 and the other side BH2 in the battery width direction BH of the battery 1. In this embodiment, an insulating resin film made of polypropylene (PP) is used as the insulating film 61.

[0022] The case 10 is made of metal (aluminum in this embodiment). The case 10 has a rectangular box shape and includes a rectangular first main wall portion 11, a rectangular second main wall portion 12 facing the first main wall portion 11, and four rectangular side walls (first side wall portion 13, second side wall portion 14, third side wall portion 15, and fourth side wall portion 16) connecting the first main wall portion 11 and the second main wall portion 12. The first main wall portion 11 and the second main wall portion 12 have larger areas than the four side walls 13, 14, 15, and 16. The first main wall portion 11 is located on one side CH1 in the battery thickness direction CH, and the second main wall portion 12 is located on the other side CH2 in the battery thickness direction CH. The first side wall 13 is located on the upper side AH1, the second side wall 14 is located on the lower side AH2 in the battery height direction AH, the third side wall 15 is located on one side BH1 in the battery width direction BH, and the fourth side wall 16 is located on the other side BH2 in the battery width direction BH. In the battery 1 of this embodiment, as described above, the elastic deformation of the case 10 causes the first main wall 11 and the second main wall 12 to press the electrode body 40 in the battery thickness direction CH (electrode body thickness direction DH).

[0023] The case 10 is composed of a case body member 31 and a case lid member 32. The case body member 31 is a rectangular cylinder with a bottom and a rectangular opening 31c. It houses a second heat transfer insulator 72, an electrode assembly 40, and a first heat transfer insulator 71, in this order. The case lid member 32 is a rectangular plate and closes the opening 31c of the case body member 31. The opening 31c of the case body member 31 and a peripheral edge 32f of the case lid member 32 are hermetically joined (welded in this embodiment) along their entire periphery. The case body member 31 forms the second main wall 12 and four side walls 13, 14, 15, and 16 of the case 10. The case lid member 32 forms the first main wall 11 of the case 10.

[0024] A safety valve 10w that ruptures and opens when the internal pressure of the case 10 exceeds the valve opening pressure is provided in the first side wall 13, which is also the upper wall of the case 10. A liquid inlet 10k is provided in the third side wall 15 of the case 10, and this liquid inlet 10k is airtightly sealed with a disk-shaped sealing member 35. Furthermore, a positive electrode terminal member 50 is fixed to the third side wall portion 15. Specifically, a rectangular insertion hole 10h is provided in the third side wall portion 15, and the positive electrode terminal member 50 made of aluminum is inserted into this insertion hole 10h. An insert-molded resin member 55 is bonded to the third side wall portion 15 and the terminal member 50 while insulating the third side wall portion 15 from the terminal member 50, thereby fixing the terminal member 50 to the third side wall portion 15. As described above, the positive electrode terminal member 50 is electrically connected to the positive electrode current collecting portion 40c of the electrode body 40 via the current collecting member 45. A negative electrode terminal member 50 is fixed to the fourth side wall portion 16 of the case 10. That is, like the positive electrode terminal member 50, the negative electrode terminal member 50 made of copper is inserted into a rectangular insertion hole 10h provided in the fourth side wall portion 16, and a resin member 55 fixes the terminal member 50 to the fourth side wall portion 16. As described above, this negative electrode terminal member 50 is conductively connected to the negative electrode current collecting portion 40d of the electrode body 40 via the current collecting member 45.

[0025] The first main wall portion 11 of the case 10 has a first pressing wall portion 17 that presses the electrode body 40 in the electrode body thickness direction DH, and the second main wall portion 12 has a second pressing wall portion 18 that presses the electrode body 40 in the electrode body thickness direction DH. Specifically, the first pressing wall portion 17 is a rectangular plate-shaped central portion of the first main wall portion 11 excluding the frame-shaped peripheral portion, and the second pressing wall portion 18 is a rectangular plate-shaped central portion of the second main wall portion 12 excluding the frame-shaped peripheral portion. The first pressing wall portion 17 has a rectangular first pressing inner surface 21 facing the inner side FH of the first pressing wall portion 17, and the second pressing wall portion 18 has a rectangular second pressing inner surface 22 facing the inner side FH of the second pressing wall portion 18.

[0026] Furthermore, the first pressing inner surface 21 includes a first area-increasing portion 23 that has been subjected to an area-increasing treatment to increase the surface area by forming numerous protrusions 25 and recesses 26, and the second pressing inner surface 22 includes a second area-increasing portion 24 that has been subjected to a similar area-increasing treatment. In this embodiment, the entire first pressing inner surface 21 becomes the first area-increasing portion 23, and the entire second pressing inner surface 22 becomes the second area-increasing portion 24. The surface area Sb of these increased area portions 23, 24 is preferably three times or more larger than the surface area before the area-increasing treatment, and in this embodiment, it is approximately 20 times larger.

[0027] In this embodiment, the area-increased portions 23 and 24 are subjected to an area-increasing process using pulsed laser light LB (see FIG. 7 ), resulting in nano-roughened portions at the nano level. Specifically, the area-increased portions 23 and 24 have numerous bowl-shaped depressions 27, each with a diameter Da of 30 to 300 μm (approximately 80 μm in this embodiment), arranged side by side with some overlapping (see FIG. 7 ). Furthermore, these bowl-shaped depressions 27 are forested with protrusions 25 made of nanopillars 28, each of which is made up of particles 28p derived from the metal constituting the case 10, linked together in a string-like fashion to form a columnar shape. Each nanopillar 28 has a height ha of 50 nm or more (approximately 200 nm in this embodiment). Recesses 26 are formed between the forest of nanopillars 28 (see FIGS. 4 and 7 ). As mentioned above, the metal constituting the case 10 is aluminum, and the nanopillars 28 are made of particles 28p composed of aluminum and aluminum oxide.

[0028] Next, the thermal insulating materials (first thermal insulating material 71 and second thermal insulating material 72) will be described. These thermal insulating materials 71, 72 are thermal insulating resin layers formed by applying and curing a paste-like resin material 75 made of a heat dissipation gap filler that is electrically insulating and thermally conductive, and have a rectangular outer shape. The thermal conductivity of the resin material 75 is 1.0 W / m·K or more, or even 2.0 W / m·K or more, and in this embodiment, 3.0 W / m·K. The first thermal insulating material 71 is interposed between the first pressing wall portion 17 of the first main wall portion 11 of the case 10 and the electrode assembly 40, and is closely joined to the first pressing wall portion 17 and also to the insulating holder 60 that covers the electrode assembly 40. On the other hand, the second heat transfer insulation material 72 is interposed between the second pressing wall portion 18 of the second main wall portion 12 of the case 10 and the electrode body 40, and is closely joined to the second pressing wall portion 18, and is also closely joined to the insulating holder 60 that covers the electrode body 40.

[0029] The contact areas Sc between the heat transfer insulators 71, 72 and the area-increased portions 23, 24 of the pressing walls 17, 18 are increased by the fact that the protrusions 25 made of the numerous nanopillars 28 of the area-increased portions 23, 24 bite into the heat transfer insulators 71, 72, and the heat transfer insulators 71, 72 bite into the recesses 26 between the numerous nanopillars 28 of the area-increased portions 23, 24. Specifically, as described above, the surface areas Sb of the area-increased portions 23, 24 are increased by about 20 times compared to the surface areas before the area-increasing process. Therefore, the contact areas Sc between the pressing walls 17, 18 and the heat transfer insulators 71, 72 are also increased by about 20 times compared to when the area-increased portions 23, 24 are not present.

[0030] In the battery 1 of this embodiment, area-increasing portions 23, 24 including numerous protrusions 25 and recesses 26 are formed on the pressing inner surfaces 21, 22 of a pair of pressing wall portions 17, 18 of the case 10, and the numerous protrusions 25 of the area-increasing portions 23, 24 are embedded into the thermal insulating materials 71, 72, and the thermal insulating materials 71, 72 are embedded into the numerous recesses 26 of the area-increasing portions 23, 24, thereby increasing the contact areas Sc between the pressing wall portions 17, 18 and the thermal insulating materials 71, 72. As a result, heat generated in the electrode assembly 40 and transferred to the thermal insulating materials 71, 72 can be efficiently transferred from the thermal insulating materials 71, 72 to the pressing wall portions 17, 18, and therefore, in the battery 1 including the thermal insulating materials 71, 72, good thermal conduction from the electrode assembly 40 to the case 10 can be achieved.

[0031] Furthermore, in this embodiment, the pair of heat transfer insulators 71, 72 are heat transfer insulators made of resin material 75, and the pair of area increasing portions 23, 24 of the case 10 are nano-level area increasing portions with a forest of nano pillars 28. Therefore, the pressing wall portions 17, 18 of the case 10 contact the heat transfer insulators 71, 72 over a particularly wide contact area Sc, which can further improve heat conduction from the heat transfer insulators 71, 72 to the pressing wall portions 17, 18.

[0032] In this embodiment, the opening 31c of the case body member 31, which houses the first heat transfer insulator 71, the electrode assembly 40, and the second heat transfer insulator 72, is joined to the peripheral edge 32f of the case lid member 32 along the entire periphery. This prevents damage to the protrusions 25 and recesses 26 of the increased-area portions 23, 24 and to the heat transfer insulators 71, 72, which would occur if the first pressing wall portion 17 and the first heat transfer insulator 71 were to shift laterally along the surface, or if the second pressing wall portion 18 and the second heat transfer insulator 72 were to shift laterally along the surface. This also ensures that the protrusions 25 and recesses 26 of the increased-area portions 23, 24 and the heat transfer insulators 71, 72 are securely engaged with each other.

[0033] Next, a method for manufacturing the battery 1 will be described (see FIGS. 5 to 11). First, in the electrode body formation / current collector connection step S1 (see FIG. 5), an electrode body 40 is formed, and positive and negative current collectors 45 are connected to the electrode body 40. Specifically, a plurality of rectangular positive electrode plates 41, a plurality of rectangular negative electrode plates 42, and a plurality of rectangular separators 43 are prepared and stacked to form the electrode body 40 (see FIG. 6). Then, the positive electrode current collector 40c and the negative electrode current collector 40d of the electrode body 40 are ultrasonically welded to the current collectors 45, respectively. Thereafter, the electrode body 40 is wrapped in a cylindrical insulating holder 60.

[0034] Separately, in the area increasing process S2 (see FIG. 5), a case body member 31Z before area increasing process and a case lid member 32Z before area increasing process are prepared, and a surface increasing process is performed on these to form a first area increasing portion 23 and a second area increasing portion 24 (see FIG. 7). In this embodiment, the surface increasing process is performed on the entire first pressing inner surface 21 of the first pressing wall portion 17 of the first main wall portion 11 formed by the case lid member 32Z, to form the first area increasing portion 23 having a large number of protrusions 25 and recesses 26. Furthermore, the surface increasing process is performed on the entire second pressing inner surface 22 of the second pressing wall portion 18 of the second main wall portion 12 of the case body member 31Z, to form the second area increasing portion 24 having a large number of protrusions 25 and recesses 26.

[0035] Specifically, pulsed laser light LB is intermittently irradiated onto the first pressing inner surface 21 of the case lid member 32Z (or the second pressing inner surface 22 of the case body member 31Z) while shifting the irradiation position, to form a first area increasing portion 23 (or a second area increasing portion 24) in which a large number of cup-shaped recesses 27 with standing nanopillars 28 are arranged in a partially overlapping manner. The laser irradiation conditions were a wavelength of 1064 nm, a peak output of 5 kW, a pulse width of 150 ns, a pitch pb of 75 μm, and a spot diameter of 80 μm.

[0036] At the portion of the first pressing inner surface 21 (or the second pressing inner surface 22) irradiated with the pulsed laser beam LB, the metal (specifically, aluminum) near the surface melts and turns into vapor. Thereafter, as the temperature of the vapor drops, it turns into aluminum and aluminum oxide particles 28p, which accumulate in the bowl-shaped recess 27. By intermittently irradiating the surface with the pulsed laser beam LB while shifting the irradiation position, the particles 28p accumulate in a string and combine to form columns, forming a forest of nano-columns 28 (see FIGS. 7 and 4).

[0037] Next, in a terminal member fixing process S3 (see FIG. 5), the positive and negative terminal members 50 are fixed to the above-mentioned case body member 31. In this embodiment, with the positive and negative terminal members 50 inserted into the pair of insertion holes 10h of the case body member 31, a pair of resin members 55 are insert-molded, and the positive and negative terminal members 50 are fixed to the case body member 31 while being insulated by the pair of resin members 55.

[0038] Next, in the placement process S4 (see Figure 5), the second heat transfer insulating material 72, the electrode body 40 and the first heat transfer insulating material 71 are placed in this order inside the above-mentioned case body member 31, and the case lid member 32 is placed on top of the case body member 31. First, in a heat transfer insulating material forming step S41 of the arrangement step S4, a first heat transfer insulating material 71 and a second heat transfer insulating material 72 are formed. In this embodiment, a resin material 75 made of a two-component heat dissipation gap filler that hardens over time is applied to the second pressing inner surface 22 (second area increasing portion 24) of the second pressing wall portion 18 of the case body member 31 to form an unhardened layer of the second heat transfer insulating material 72 (see FIG. 8). At this time, the resin material 75 is also filled into the recesses 26 between the nanopillars 28 (protrusions 25) that stand in the second area increasing portion 24 (see FIG. 4), so that the second pressing wall portion 18 and the second heat transfer insulating material 72 come into contact with each other over a wide contact area Sc. Separately, a resin material 75 made of a heat dissipation gap filler is also applied to the first pressing inner surface 21 (first area increasing portion 23) of the first pressing wall portion 17 of the case lid member 32 to form an uncured layer of first heat transfer insulating material 71 (see FIG. 8). At this time, the resin material 75 is also filled into the recesses 26 between the nanopillars 28 (protrusions 25) that stand in the first area increasing portion 23 (see FIG. 4), so that the first pressing wall portion 17 and the first heat transfer insulating material 71 come into contact with each other over a wide contact area Sc.

[0039] Next, in the electrode body accommodation step S42 of the placement step S4, the electrode body 40 covered with the aforementioned insulating holder 60 is accommodated in the case main body member 31 on which the second heat transfer insulating material 72 is formed, and the uncured second heat transfer insulating material 72 is adhered to the insulating holder 60. Thereafter, in a terminal member connecting step S43 of the arrangement step S4, a laser beam LC is applied to the contact portion between the positive electrode current collecting member 45 connected to the positive electrode current collecting portion 40c of the electrode body 40 and the positive electrode terminal member 50 fixed to the case body member 31, thereby laser welding the current collecting member 45 and the terminal member 50 (see FIG. 9). Similarly, the negative electrode current collecting member 45 connected to the negative electrode current collecting portion 40d of the electrode body 40 and the negative electrode terminal member 50 fixed to the case body member 31 are also laser welded. Thereafter, in a case lid member placement step S44 of the placement step S4, the case lid member 32 on which the first heat transfer insulating material 71 has been formed is placed on the case body member 31, and the uncured first heat transfer insulating material 71 is brought into close contact with the insulating holder 60 (see FIG. 10). Thus, the second heat transfer insulating material 72, the electrode body 40, and the first heat transfer insulating material 71 are housed in this order within the case body member 31, and the case lid member 32 is placed on the case body member 31.

[0040] Next, in the case formation process S5 (see FIG. 5), the gap between the first main wall portion 11 of the case lid member 32 and the second main wall portion 12 of the case body member 31 is narrowed, and the first heat transfer insulator 71, the electrode assembly 40, and the second heat transfer insulator 72 are pressed. In this state, the opening 31c of the case body member 31 and the peripheral edge portion 32f of the case lid member 32 are joined along the entire periphery to form the case 10 (see FIG. 11). An external force Fa is applied to the first main wall portion 11 and the second main wall portion 12 to narrow the gap between the first main wall portion 11 and the second main wall portion 12, and the first heat transfer insulator 71, the electrode assembly 40, and the second heat transfer insulator 72 are pressed in the battery thickness direction CH (electrode assembly thickness direction DH). The peripheral edge portion 32f of the case lid member 32 is brought into contact with the opening 31c of the case body member 31. Then, laser light LD is irradiated onto the opening 31c of the case body member 31 and the peripheral edge 32f of the case lid member 32, and these are laser-welded airtightly along their entire periphery to form the case 10. After the case 10 is formed, the first main wall portion 11 and the second main wall portion 12 press against the electrode body 40 and the like due to the elasticity of the case 10.

[0041] Next, in a liquid injection and sealing step S6 (see FIG. 5), after the pair of heat transfer insulators 71, 72 have completely hardened, the electrolyte 5 is injected into the case 10 through the liquid injection hole 10k, and the electrolyte 5 is impregnated into the electrode body 40. Thereafter, the liquid injection hole 10k is airtightly sealed with a sealing member 35. Next, in the initial charge / aging step S7, the battery 1 is initially charged. After that, the battery 1 is left standing for a predetermined time to age the battery 1. In this way, the battery 1 is completed.

[0042] In the manufacturing method of the battery 1 of this embodiment, the electrode body 40 is first housed in the case body member 31, which is a bottomed rectangular tube that forms the second main wall portion 12 and four side wall portions 13, 14, 15, and 16, so that the electrode body 40 can be easily housed in the case body member 31. Then, the opening 31c of the case body member 31 is closed with the case lid member 32 that forms the first main wall portion 11, and the opening 31c of the case body member 31 and the peripheral edge portion 32f of the case lid member 32 are joined together, so that the battery 1 can be easily manufactured.

[0043] (Variations) Next, a modified embodiment of the above embodiment will be described. Note that descriptions of parts similar to those of the embodiment will be omitted or simplified. In the battery 1 of the embodiment, the electrode assembly 40 is wrapped in an insulating holder 60 and then housed in a case 10. In contrast, the battery (electricity storage device) 100 of this modified embodiment differs in that the electrode assembly 40 is housed in the case 10 without being wrapped in an insulating holder. That is, in the battery 100, the first thermally conductive insulator 71 and the second thermally conductive insulator 72 are in direct contact with the electrode assembly 40. Therefore, heat generated in the electrode assembly 40 is conducted directly to the first thermally conductive insulator 71 and the second thermally conductive insulator 72 without passing through the insulating holder.

[0044] In the battery 100 having such a configuration, similarly to the embodiment, the contact areas Sc between the pair of pressing wall portions 17, 18 of the case 10 and the pair of heat transfer insulators 71, 72 are increased, so that heat generated in the electrode body 40 and transferred to the heat transfer insulators 71, 72 can be efficiently transferred from the heat transfer insulators 71, 72 to the pressing wall portions 17, 18. In addition, the same parts as in the embodiment also achieve the same effects as in the embodiment in this modified embodiment.

[0045] 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. For example, in the embodiment, the electrode body is exemplified as a laminated electrode body 40, but is not limited to this. The electrode body may be, for example, a wound electrode body in which a strip-shaped positive electrode plate and a strip-shaped negative electrode plate are stacked on top of each other with a pair of strip-shaped separators interposed therebetween and wound together to form a flattened electrode body. Furthermore, in the embodiment, the battery 1 is exemplified as having a single electrode body 40 inside the case 10, but the present invention is not limited to this, and the battery may have a plurality of electrode bodies inside the case.

[0046] In the embodiment, the area increasing portions 23, 24 having the numerous protrusions 25 and recesses 26 are formed only on the pair of pressing inner surfaces 21, 22 of the inner surface of the case 10, but this is not limited to this. For example, the numerous protrusions 25 and recesses 26 may also be formed on portions of the inner surface of the case 10 other than the pressing inner surfaces 21, 22. In the embodiment, the heat transfer insulating materials 71, 72 are formed by applying the resin material 75 made of a heat dissipation gap filler to the pair of pressing inner surfaces 21, 22, but this is not limiting. Flexible heat transfer insulating sheets, such as insulating and thermally conductive gel sheets, may be disposed between the pair of pressing inner surfaces 21, 22 and the electrode body 40, respectively, to provide the heat transfer insulating materials made of heat transfer insulating sheets. [Explanation of symbols]

[0047] 1,100 batteries (energy storage devices) 10 cases 11 First main wall 12 Second main wall 13 First side wall 14 Second side wall 15 Third side wall 16 Fourth side wall 17 First pressing wall 18 Second pressing wall portion 21 First pressing inner surface 22 Second pressing inner surface 23 First area increase section 24 Second area increase section 25 Convex part 26 Recess 28 Nano Pillars 28p (nanopillar) particles 31 Case body material 31c opening 32 Case cover member 32f Periphery 40 Electrode body 60 Insulation holder 61 Insulating film 71 First heat transfer insulation material 72 Second heat transfer insulation material 75 Resin material FH (Inside of pressing wall) Sc (contact area between the pressing wall and the heat transfer insulation material) ha (nanopillar) height

Claims

1. An electrode body; a metal case that houses the electrode body, The case has a pressing wall portion that presses the electrode body. An electricity storage device, The heat-transmitting insulating material is further provided, which is electrically insulating and thermally conductive and is interposed between the pressing wall portion and the electrode body, and is in close contact with the pressing wall portion, and is in close contact with an insulating holder made of an insulating film covering the electrode body or directly with the electrode body, The pressing wall portion has a pressing inner surface facing inward of the pressing wall portion, the pressing inner surface includes an area increasing portion that has been subjected to an area increasing treatment to form a number of protrusions and recesses to increase the surface area, The heat transfer insulating material and the area increasing portion are The large number of protrusions of the area-increasing portion bite into the heat-transfer insulating material, and the heat-transfer insulating material bites into the large number of recesses of the area-increasing portion, thereby increasing the contact area between the pressing wall portion and the heat-transfer insulating material. Energy storage device.

2. The electricity storage device according to claim 1 , The heat-transfer insulating material is made of a resin material having insulating and thermally conductive properties, The area increasing portion is The protrusions are made of nanopillars with a height of 50 nm or more, each of which is formed by connecting particles derived from the metal that forms the case in a string-like pattern, and the recesses are formed between the nanopillars. Energy storage device.

3. The electricity storage device according to claim 1 or 2, The case is The housing has a rectangular box shape, a rectangular first main wall portion, a rectangular second main wall portion facing the first main wall portion, and four rectangular side wall portions connecting the first main wall portion and the second main wall portion, the first main wall portion includes a first pressing wall portion that is the pressing wall portion, the second main wall portion includes a second pressing wall portion that is the pressing wall portion, The electricity storage device is a first heat transfer insulator, which is the heat transfer insulator, is provided between the first pressing wall portion of the first main wall portion and the electrode body; a second heat transfer insulator, which is the heat transfer insulator, is provided between the second pressing wall portion of the second main wall portion and the electrode body; The case is a case body member that forms the second main wall portion and the four side wall portions, has a bottomed rectangular tubular shape with a rectangular opening, and accommodates the second thermal insulation material, the electrode body, and the first thermal insulation material in this order; a rectangular case lid member that forms the first main wall portion and closes the opening of the case body member, The opening of the case body member and the peripheral edge of the case lid member are joined together over their entire peripheries. Energy storage device.

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