Spacer, method for manufacturing spacer, and battery pack
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- SUMITOMO RIKO CO LTD
- Filing Date
- 2026-01-21
- Publication Date
- 2026-08-06
Smart Images
Figure JP2026001851_06082026_PF_FP_ABST
Abstract
Description
Spacer, Method for Manufacturing Spacer, and Assembled Battery
[0001] The present disclosure relates to a spacer, a method for manufacturing the spacer, and an assembled battery.
[0002] Patent Documents 1 to 3 disclose spacers (heat insulation material units) arranged side by side with battery cells. The spacer is configured to cover the heat insulation material with a cover film. The cover film is formed of a first film covering one side of the heat insulation material and a second film covering the other side of the heat insulation material, and the first film and the second film are joined over the entire circumference.
[0003] Japanese Unexamined Patent Application Publication No. 2023-53818, Japanese Unexamined Patent Application Publication No. 2024-120378, Japanese Unexamined Patent Application Publication No. 2009-287586
[0004] In Patent Documents 1 to 3, the first film and the second film are joined to seal. However, depending on the material and thickness of the film, the bonding strength may not be sufficient, and there is a risk that sufficient sealing performance cannot be obtained.
[0005] The present disclosure has been made in view of such a background, and aims to provide a spacer, a method for manufacturing the spacer, and an assembled battery capable of improving the sealing performance at the joint portion.
[0006] One aspect of the present disclosure is a spacer arranged to face an object, including a heat insulation material having a first surface facing the object and a second surface that is the back surface of the first surface, a first cover portion covering the first surface of the heat insulation material, and a second cover portion covering the second surface of the heat insulation material. The heat insulation material is accommodated in an internal space formed by the first cover portion and the second cover portion, and a cover having an overlapping portion where at least a part of the periphery has the first cover portion and the second cover portion arranged overlappingly, an inner member sandwiched between the first cover portion and the second cover portion at least in the overlapping portion, and a sealing line that seals the overlapping portion of the cover by joining the first cover portion and the inner member and joining the second cover portion and the inner member.
[0007] Another aspect of the present disclosure is a method for manufacturing a spacer, comprising arranging an insulating material in the internal space, arranging an inner member between the first cover portion and the second cover portion at least in the overlapping portion, and forming the seal line by heating the overlapping portion.
[0008] Another aspect of the present disclosure comprises a housing including a bottom surface, a battery cell which is the object housed in the housing, and a spacer housed in the housing and positioned opposite the battery cell, wherein the sealing wire is located in a battery pack opposite the bottom surface.
[0009] The spacer provides a sealing wire that seals the overlapping portion of the cover. In this configuration, an inner member is sandwiched between the first and second cover portions at the overlapping portion of the cover. The sealing wire is formed by joining the first cover portion to the inner member and also by joining the second cover portion to the inner member. In other words, the sealing wire includes the inner member in addition to the first and second cover portions. Consequently, the bonding strength of the sealing wire is improved. Furthermore, the rigidity of the sealing wire is increased by including the inner member compared to the case where only the first and second cover portions are joined. Consequently, the shape stability of the sealing wire is improved. In this way, the sealing performance of the sealing wire is improved.
[0010] According to the method for manufacturing the spacer, the spacer can be reliably manufactured. Furthermore, because the battery pack includes the spacer, it exhibits the aforementioned effects.
[0011] Furthermore, in the aforementioned battery pack, the sealing wire is positioned opposite the bottom surface of the housing. Here, the rigidity of the sealing wire of the spacer is increased by including the inner member compared to the case where only the first cover portion and the second cover portion are joined. Because the highly rigid sealing wire is positioned opposite the bottom surface of the housing, the positioning accuracy in the height direction of the spacer is improved. Since the relative position between the battery cell and the spacer can be made highly accurate, the heat insulation performance for the battery cell can be improved.
[0012] Based on the above, we can provide a spacer that can improve the sealing performance of a sealing wire, a method for manufacturing the spacer, and a battery pack.
[0013] Figure 1 is a cross-sectional view showing a battery pack in Embodiment 1. Figure 2 is a perspective view of a spacer constituting the battery pack. Figure 3 is a diagram showing the spacer. Figure 4 is a view of the spacer in Figure 3 from the right. Figure 5 is an enlarged cross-sectional view taken along V-V in Figure 4. Figure 6 is an enlarged schematic diagram showing the thermal insulation material constituting the spacer. Figure 7 is an enlarged schematic diagram showing a part of the inorganic particles constituting the thermal insulation material. Figure 8 is a flowchart showing the method for manufacturing the spacer in Embodiment 1. Figure 9 is a diagram illustrating S1 in Figure 8. Figure 10 is a diagram illustrating the heating tool in S2 in Figure 8, where (a) in Figure 10 is a plan view and (b) in Figure 10 is a cross-sectional view taken along B-B. Figure 11 is a diagram illustrating S2 in Figure 8, where (a) in Figure 11 is a plan view and (b) in Figure 11 is a cross-sectional view taken along B-B. Figure 12 is a diagram illustrating S3 in Figure 8, where (a) in Figure 12 is a plan view and (b) in Figure 12 is a cross-sectional view taken along B-B. Figure 13 is a diagram illustrating S4 in Figure 8, where (a) is a plan view and (b) is a cross-sectional view taken along line B-B. Figure 14 is a diagram illustrating S5 in Figure 8, where (a) is a plan view and (b) is a cross-sectional view taken along line B-B. Figure 15 is a diagram illustrating the method for manufacturing a spacer in Embodiment 2, illustrating S1 in Figure 8. Figure 16 is a diagram illustrating the method for manufacturing a spacer in Embodiment 3, illustrating S1 in Figure 8. Figure 17 is a diagram illustrating the method for manufacturing a spacer in Embodiment 4, illustrating S1 in Figure 8.
[0014] (Embodiment 1) 1. Battery pack 1 The battery pack 1 will be described with reference to Figure 1. The battery pack 1 includes a housing 2, a plurality of battery cells 3, a plurality of spacers 4, and a bus bar 5.
[0015] The housing 2 includes at least a bottom surface 11. The bottom surface 11 is not limited to being located downwards in the vertical direction, but may be located in other positions. The housing 2 further includes a pair of side walls 12 and 13. Multiple battery cells 3 are arranged on the bottom surface 11. The bottom surface 11 may include a heat conductive member or a cooling member to cool the battery cells 3. The pair of side walls 12 and 13 are arranged opposite each other in the left-right direction of Figure 1, and are configured to sandwich the arranged multiple battery cells 3 from both sides. The pair of side walls 12 and 13 are formed of, for example, metal or resin. The housing 2 may also include a pair of side walls that are opposite each other in the direction normal to the plane of the paper in Figure 1.
[0016] The bottom surface 11 and the pair of side walls 12 and 13 that constitute the housing 2 may be made of different materials or of the same material.
[0017] Multiple battery cells 3 are housed in a housing 2. The multiple battery cells 3 are arranged on the bottom surface 11 of the housing 2, between a pair of side walls 12 and 13. Each battery cell 3 is positioned vertically with respect to the bottom surface 11 of the housing 2. Each battery cell 3 is formed in a flattened shape. The flattened surfaces of the battery cells 3 are arranged to face each other. The shape of the outer circumferential surface of the battery cell 3 (the contour shape viewed from the normal direction of the flattened surface) is arbitrary. For example, the shape of the outer circumferential surface of the battery cell 3 is formed in a polygon, such as a rectangle.
[0018] The battery cell 3 is, for example, a rechargeable storage battery (also called a secondary battery). The battery cell 3 is one selected from the group, for example, lithium-ion batteries, lead-acid batteries, nickel-metal hydride batteries, nickel-cadmium batteries, and all-solid-state batteries. The battery cell 3 generates heat during charging and discharging. The heat generated by the battery cell 3 is transferred, for example, to the bottom surface 11 of the housing 2. In this way, the battery cell 3 is cooled.
[0019] Furthermore, the battery cell 3 expands when charged and contracts when discharged. Therefore, the battery cell 3 repeatedly expands and contracts as charging and discharging are repeated. Here, as described above, the battery cell 3 is formed in a flattened shape. Therefore, the battery cell 3 mainly expands and contracts in the direction normal to the flattened plane (left-right direction in Figure 1).
[0020] The battery cell 3 includes a cell housing (not shown) made of, for example, metal or resin, and a cell body (not shown) housed in the cell housing. The battery cell 3 expands and contracts in accordance with the expansion and contraction of the cell body. The structure of the battery cell 3 is known and therefore omitted.
[0021] Multiple spacers 4 are housed in the housing 2. Each spacer 4 is formed in a flattened shape. For example, the thickness of a spacer 4 is thinner than the thickness of a battery cell 3. Some of the multiple spacers 4 are sandwiched between adjacent battery cells 3. Other parts of the multiple spacers 4 are sandwiched between the battery cells 3 and the side walls 12 and 13, respectively. In other words, at least one side of each spacer 4 is positioned facing the battery cell 3. At least one side of each spacer 4 may be in direct contact with the battery cell 3, or it may be positioned between the spacer 4 and the battery cell 3 via other members such as heat transfer members or thickness adjustment members.
[0022] The spacers 4, like the battery cells 3, are positioned on the bottom surface 11 of the housing 2, between the pair of side walls 12 and 13. Each spacer 4 is positioned vertically with respect to the bottom surface 11 of the housing 2. If the normal to the bottom surface 11 of the housing 2 is horizontal, each spacer 4 is positioned horizontally.
[0023] Spacer 4 has thermal insulation properties. In other words, spacer 4 suppresses the transfer of heat from one adjacent battery cell 3 to the opposite battery cell 3. If heat from one battery cell 3 is transferred to an adjacent battery cell 3, it may cause a heat chain reaction. As a result, the lifespan of the battery cell 3 will decrease. Therefore, the thermal insulation properties of spacer 4 help to suppress the reduction in the lifespan of the battery cell 3.
[0024] Furthermore, it is preferable that the spacer 4 is elastic. As described above, the battery cell 3 expands and contracts with charging and discharging. When the battery cell 3 expands and contracts, the spacer 4 is required to hold the battery cell 3 within a predetermined pressure range. This helps to suppress the reduction in the lifespan of the battery cell 3. Therefore, the spacer 4 is formed to have a predetermined elastic force when it deforms in accordance with the expansion and contraction of the battery cell 3.
[0025] The busbar 5 is positioned on top of the multiple battery cells 3, spanning across the multiple battery cells 3. The busbar 5 is made of an electrically conductive material and is electrically connected to the electrodes of the battery cells 3. Note that the busbar 5 is not limited to being positioned above the battery cells 3, but may also be positioned on the sides.
[0026] 2. Spacer 4 The spacer 4 will be explained with reference to Figures 2 to 5. In Figures 2 to 4, the vertical direction coincides with the vertical direction in Figure 1. Therefore, the lower end of the spacer 4 shown in Figures 2 to 4 is supported by the bottom surface 11 of the housing 2 shown in Figure 1.
[0027] The spacer 4 includes an insulating material 21 (shown in Figure 5), a cover 22, an inner member 23, and a sealing wire 24. However, the spacer 4 may include elements other than those described above (21-24).
[0028] The thermal insulation material 21 is formed in a flattened shape. Preferably, the contour shape of the thermal insulation material 21, as viewed from the normal direction of the flattened surface, corresponds to the outer shape of the battery cell 3. However, it is preferable that the thermal insulation material 21 has a shape that is slightly smaller than the outer shape of the battery cell 3. For example, the thermal insulation material 21 is formed in a polygon, such as a rectangle.
[0029] As shown in Figure 5, the thermal insulation material 21 includes a first surface 21a and a second surface 21b that are facing away from each other and constitute a flattened surface. The first surface 21a faces the flattened surface of the battery cell 3. The second surface 21b is the back surface of the first surface 21a. However, if the spacer 4 is sandwiched between adjacent battery cells 3, the second surface 21b also faces the flattened surface of the battery cell 3. The first surface 21a and the second surface 21b are formed into any shape, such as a rectangle. The thermal insulation material 21 also includes a circumferential surface 21c. If the first surface 21a and the second surface 21b are rectangular, there are four circumferential surfaces 21c.
[0030] The thermal insulation material 21 can be made from various materials as long as they have thermal insulation properties. The thermal insulation material 21 may exhibit thermal insulation properties through the materials that make it up, for example, or it may exhibit thermal insulation properties by holding a gas such as air inside. The thermal insulation material 21 may contain multiple particles, for example. The thermal insulation material 21 may be made up of multiple particles bonded together as a single unit, or the multiple particles may be arranged independently.
[0031] Furthermore, the thermal insulation material 21 may include materials with various purposes in addition to materials having thermal insulation properties. For example, the thermal insulation material 21 may include reinforcing materials to improve the strength of the thermal insulation material 21, or base materials to hold the thermal insulation material. Examples of reinforcing materials include reinforcing fibers. Reinforcing fibers can be inorganic fibers such as glass fibers or organic fibers such as resin fibers. In addition to being thread-like, reinforcing fibers can also be formed into, for example, woven fabrics or nonwoven fabrics.
[0032] The cover 22 is formed from a flexible sheet. The cover 22 includes a first cover portion 22a that covers the first surface 21a of the heat insulating material 21, and a second cover portion 22b that covers the second surface 21b of the heat insulating material 21. The first cover portion 22a and the second cover portion 22b may each be made from a plurality of independent sheets, or they may be made from a single sheet.
[0033] The shapes of the first cover portion 22a and the second cover portion 22b are not particularly limited. For example, as shown in Figures 2 to 5, the first cover portion 22a is shaped and has a recess in the center. The recess corresponds to the shape of the heat insulating material 21. The second cover portion 22b is formed in a planar shape. However, the first cover portion 22a and the second cover portion 22b may both have a recess in the center.
[0034] The cover 22 then houses the thermal insulation material 21. That is, the thermal insulation material 21 is housed in the internal space 22c formed by the first cover portion 22a and the second cover portion 22b. In Figures 2 to 5, for example, the thermal insulation material 21 is housed in a recess in the first cover portion 22a, and the second cover portion 22b covers it. If recesses are formed in the first cover portion 22a and the second cover portion 22b, the thermal insulation material 21 is housed in the recesses of both portions.
[0035] As shown in Figures 2 and 4, the cover 22 includes an overlapping portion 22d in which the first cover portion 22a and the second cover portion 22b are arranged in overlapping positions in at least a portion of the periphery of the cover 22. In the overlapping portion 22d, the first cover portion 22a and the second cover portion 22b are overlapped in their respective surface normal directions. In other words, the overlapping portion 22d has a shape that extends outward from the circumferential surface of the insulation material 21, i.e., a flange shape.
[0036] The overlapping portion 22d may be located around the entire circumference of the cover 22. In this case, the overlapping portion 22d will be located around the entire circumferential surface of the insulation material 21. Alternatively, the overlapping portion 22d may be located only around a portion of the periphery of the cover 22. In this case, the overlapping portion 22d will be located only around a portion of the circumferential surface of the insulation material 21. For example, in Figure 4, the overlapping portion 22d may be located on the left and right pair of sides of the rectangle, but not on the top and bottom pair of sides.
[0037] The purpose of enclosing the insulation material 21 with the cover 22 is optional. For example, the cover 22 may serve to protect the surface of the insulation material 21. Also, if the insulation material 21 is formed of multiple particles, the cover 22 may function as a component to prevent dust generation from the insulation material 21. The cover 22 may also function to maintain the shape of the insulation material 21.
[0038] The cover 22 may be formed from a sheet without through holes. However, the cover 22 may have fine through holes.
[0039] The material of the cover 22 can be, for example, resin, cloth, paper, or metal. The cover 22 may be formed from a single material or may have a multi-layer structure made of multiple different materials. For example, the cover 22 may have a structure formed from a metal layer and a resin layer, a structure formed from a cloth layer containing resin and a metal layer, or a structure formed from a resin layer and a cloth layer.
[0040] The resin may include a thermoplastic resin. Examples of such resins include polyvinyl chloride (PVC), polypropylene (PP), polyethylene (PE), polystyrene (PS), and polyethylene terephthalate (PET). Examples of fabrics include woven fabrics and nonwoven fabrics. The fibers of the fabric may also include a thermoplastic resin.
[0041] The thickness D22 of the cover 22 is not particularly limited. Furthermore, the thickness D22 of the cover 22 varies depending on the material. For example, the thickness D22 of the cover 22 is between 5 μm and 1 mm.
[0042] The inner member 23 is formed from a flexible sheet. The inner member 23 is sandwiched between the first cover portion 22a and the second cover portion 22b at least in the overlapping portion 22d of the cover 22. In Figures 2 to 5, the inner member 23 is positioned inside the cover 22 and constitutes an inner cover that covers the heat insulating material 21.
[0043] The inner member 23 includes a first inner cover portion 23a and a second inner cover portion 23b. The first inner cover portion 23a is disposed between the heat insulating material 21 and the first cover portion 22a, and covers the first surface 21a of the heat insulating material 21. The second inner cover portion 23b is disposed between the heat insulating material 21 and the second cover portion 22b, and covers the second surface 21b of the heat insulating material 21. Note that the first inner cover portion 23a and the second inner cover portion 23b may each be a plurality of independent sheets, or may be formed of a single sheet.
[0044] The shapes of the first inner cover portion 23a and the second inner cover portion 23b are not particularly limited. For example, as shown in FIGS. 2 to 5, the first inner cover portion 23a is shaped, and a recess is formed in the center. The recess corresponds to the shape of the heat insulating material 21. The second inner cover portion 23b is formed in a planar shape. However, the first inner cover portion 23a and the second inner cover portion 23b may have a recess in the center.
[0045] Then, the inner member 23 accommodates the heat insulating material 21 inside the cover 22. That is, the heat insulating material 21 is accommodated in the internal space 23c formed by the first inner cover portion 23a and the second inner cover portion 23b. In FIGS. 2 to 5, for example, the heat insulating material 21 is accommodated in the recess of the first inner cover portion 23a, and the second inner cover portion 23b serves as a lid. Note that when recesses are formed in the first inner cover portion 23a and the second inner cover portion 23b, the heat insulating material 21 is accommodated in the recesses of both.
[0046] Here, the cover 22 disposes the unit in which the heat insulating material 21 is accommodated in the inner member 23 inside. Therefore, the inner shape of the first cover portion 22a corresponds to the outer shape of the first inner cover portion 23a. Also, the inner shape of the second cover portion 22b corresponds to the outer shape of the second inner cover portion 23b.
[0047] As shown in FIGS. 2 and 4, the inner member 23 includes an overlapping portion 23d in which at least a part of the periphery of the inner member 23 has the first inner cover portion 23a and the second inner cover portion 23b arranged overlappingly. In the overlapping portion 23d, the first inner cover portion 23a and the second inner cover portion 23b are overlapped in their respective surface normal directions. That is, the overlapping portion 23d has a shape that extends outward from the peripheral surface of the heat insulating material 21, that is, a flange shape.
[0048] The overlapping portion 23d may be located over the entire circumference of the inner member 23. In this case, the overlapping portion 23d is located over the entire peripheral surface of the heat insulating material 21. Also, the overlapping portion 23d may be located only at a part of the periphery of the inner member 23. In this case, the overlapping portion 23d is located only at a part of the peripheral surface of the heat insulating material 21. For example, in FIG. 4, the overlapping portion 23d may be located on a pair of left and right sides of the rectangle and not on a pair of upper and lower sides.
[0049] However, the overlapping portion 23d of the inner member 23 is located at a position corresponding to the overlapping portion 22d of the cover 22. Therefore, the overlapping portion 23d of the inner member 23 is sandwiched by the overlapping portion 22d of the cover 22. In other words, in at least a part of the overlapping portion 22d of the cover 22, the first cover portion 22a and the second cover portion 22b are not in direct contact, and the inner member 23 exists as an intervening object.
[0050] The purpose of accommodating the heat insulating material 21 by the inner member 23 is optional. For example, the inner member 23 may have the purpose of protecting the surface of the heat insulating material 21. Also, when the heat insulating material 21 is formed of a plurality of particles, the inner member 23 may function as a member for preventing dust generation by the heat insulating material 21. The inner member 23 may function as maintaining the shape of the heat insulating material 21.
[0051] The material of the inner member 23 can be, for example, resin, cloth, paper, or metal. The inner member 23 may be formed from a single material or may have a multi-layer structure made of multiple different materials. For example, the inner member 23 may have a structure formed from a metal layer and a resin layer, a structure formed from a cloth layer containing resin and a metal layer, or a structure formed from a resin layer and a cloth layer.
[0052] The resin may include a thermoplastic resin. Examples of such resins include polyvinyl chloride (PVC), polypropylene (PP), polyethylene (PE), polystyrene (PS), and polyethylene terephthalate (PET). Examples of fabrics include woven fabrics and nonwoven fabrics. The fibers of the fabric may include the aforementioned thermoplastic resin.
[0053] For example, the cover 22 may be made of resin and the inner member 23 may be made of nonwoven or woven fabric. In this case, the cover 22 can function as a member that prevents dust generation by the heat insulating material 21, and the inner member 23 can function as a member that protects the surface of the heat insulating material 21.
[0054] The thickness D23 of the inner member 23 is not particularly limited. Furthermore, the thickness D23 of the inner member 23 varies depending on the material. For example, the thickness D23 of the inner member 23 is between 10 μm and 5 mm.
[0055] The thickness D23 of the inner member 23 should be greater than the thickness D22 of the cover 22. However, the thickness D23 of the inner member 23 may be less than the thickness S22 of the cover 22.
[0056] The sealing wire 24 seals the overlapping portion 22d of the cover 22. When the overlapping portion 22d of the cover 22 is not sealed, it has an opening between the first cover portion 22a and the second cover portion 22b. In other words, the sealing wire 24 seals this opening. In this way, the sealing wire 24 seals the overlapping portion 22d of the cover 22 by joining the first cover portion 22a and the second cover portion 22b.
[0057] However, an inner member 23 is interposed in the overlapping portion 22d of the cover 22. In particular, an overlapping portion 23d of the inner member 23 is interposed in the overlapping portion 22d of the cover 22. Therefore, the first cover portion 22a and the second cover portion 22b are joined via the inner member 23. More specifically, the sealing wire 24 seals the overlapping portion 22d of the cover 22 by joining the first cover portion 22a and the inner member 23, and also by joining the second cover portion 22b and the inner member 23.
[0058] As described above, the sealing wire 24 seals the overlapping portion 22d of the cover 22 by joining the first cover portion 22a and the second cover portion 22b. In other words, at the overlapping portion 22d of the cover 22, the first cover portion 22a and the first inner cover portion 23a are joined, the second cover portion 22b and the second inner cover portion 23b are joined, and furthermore, the first inner cover portion 23a and the second inner cover portion 23b are joined.
[0059] The sealing wire 24 is formed continuously in the overlapping portion 22d of the cover 22. Therefore, the sealing wire 24 seals the overlapping portion 22d without interruption in the direction in which the sealing wire 24 extends.
[0060] The line width of the sealing wire 24 can be, for example, 0.2 mm to 10.0 mm. Preferably, the line width of the sealing wire 24 is 0.3 mm to 3.0 mm, and more preferably 0.3 mm to 1.0 mm.
[0061] The joining method using the sealing wire 24 includes welding and joining with a joining material. Examples of welding methods include heat welding, high-frequency welding, ultrasonic welding, and laser welding. The material of the cover 22 is selected according to the joining method.
[0062] When welding is used as the joining method for the sealing wire 24, it is preferable that at least one of the cover 22 and the inner member 23 melts. In this case, it is preferable that at least one of the cover 22 and the inner member 23 contains a thermoplastic resin. For example, the sealing wire 24 may be sealed by welding the first cover portion 22a to the inner member 23 and the second cover portion 22b to the inner member 23, thereby sealing the overlapping portion 22d of the cover 22. It can be easily manufactured by welding the outer cover 22 to the inner member 23. For example, when heat welding is used, it is preferable that the inner member 23 be made of a material with a higher melting point than the cover 22. However, the reverse is also possible.
[0063] When the inner member 23 has a first inner cover portion 23a and a second inner cover portion 23b, and the joining means for the seal wire 24 is welding, it is preferable that at least one of the first inner cover portion 23a and the second inner cover portion 23b contains a thermoplastic resin. The overlapping portion 22d of the cover 22 may then be sealed by any of the following methods to form the seal wire 24.
[0064] Firstly, the welding of the first cover portion 22a and the first inner cover portion 23a, the welding of the second cover portion 22b and the second inner cover portion 23b, and the welding of the first inner cover portion 23a and the second inner cover portion 23b may be performed simultaneously.
[0065] Secondly, the first inner cover portion 23a and the second inner cover portion 23b may be welded together first, and then the first cover portion 22a and the first inner cover portion 23a, and the second cover portion 22b and the second inner cover portion 23b may be welded together. In this case, it is preferable that the welded locations of the first inner cover portion 23a and the second inner cover portion 23b, the welded locations of the first cover portion 22a and the first inner cover portion 23a, and the welded locations of the second cover portion 22a and the second inner cover portion 23b overlap in at least a portion of the area.
[0066] A third method may be used as follows: First, the first inner cover portion 23a and the second inner cover portion 23b are welded together. After that, the welding of the first cover portion 22a and the first inner cover portion 23a, the welding of the second cover portion 22b and the second inner cover portion 23b, and the welding of the first inner cover portion 23a and the second inner cover portion 23b may be performed simultaneously. In this case, the welded locations of the first inner cover portion 23a and the second inner cover portion 23b, the welded locations of the first cover portion 22a and the first inner cover portion 23a, and the welded locations of the second cover portion 22a and the second inner cover portion 23b may overlap in some areas, or they may not overlap at all.
[0067] Here, the overlapping portion 22d of the cover 22 is formed to surround the periphery of the heat insulating material 21. Therefore, the sealing wire 24 is formed to surround the periphery of the heat insulating material 21. In other words, the sealing wire 24 is formed at positions corresponding to all sides of the heat insulating material 21. Note that "surrounding the periphery of the heat insulating material 21" includes not only cases where the heat insulating material 21 is continuously surrounded around its entire circumference, but also cases where it is intermittently surrounded with partial breaks. However, in the battery pack 1, it is preferable that the sealing wire 24 be positioned opposite the bottom surface 11 of the housing 2.
[0068] Furthermore, the sealing wire 24 is formed by a first cover portion 22a, a second cover portion 22b, a first inner cover portion 23a, and a second inner cover portion 23b. Therefore, the thickness of the sealing wire 24 is thinner than the thickness of the insulation material 21.
[0069] 3. Example of the thermal insulation material 21 As described above, it is preferable that the spacer 4 has elasticity in addition to having thermal insulation properties. This allows the spacer 4 to hold the battery cell 3 in place within a predetermined pressure range when the battery cell 3 expands and contracts. In this case, it is preferable that the thermal insulation material 21 be made of a material that has thermal insulation properties and is also elastic.
[0070] As described above, the thermal insulation material 21 can be made from various materials as long as it has thermal insulation properties. As an example of the thermal insulation material 21, a case in which the thermal insulation material 21 is made from a material that has thermal insulation properties and is elastic will be explained with reference to Figures 6 and 7.
[0071] As shown in Figure 6, the thermal insulation material 21 is manufactured by pressure molding a composition having a porous structure powder 31.
[0072] As shown in Figure 7, the porous structure has a framework formed by the linkage of multiple primary particles 31a, with pores 31b between the framework. The diameter of the primary particles 31a forming the framework is preferably about 2 to 5 nm, and the size of the pores 31b formed between the framework is preferably about 10 to 50 nm. If most of the pores 31b are so-called mesopores with a size of 50 nm or less, the mesopores are smaller than the mean free path of air, thus restricting air convection and inhibiting heat transfer. The primary particles 31a (inorganic particles) forming the framework are mainly composed of inorganic materials such as silica, alumina, zirconia, and titania. A porous structure in which the primary particles are silica is preferred because of its excellent chemical stability.
[0073] An example of a porous structure is silica aerogel. Depending on the drying method used in the production of aerogel, those dried at atmospheric pressure are sometimes called "xerogels," and those dried under supercritical conditions are sometimes called "aerogels," but both are referred to as "aerogels." Silica aerogels are suitable because they have a good balance between the size of the skeleton and the size of the pores. Silica aerogels are produced, for example, by a sol-gel reaction of a solution containing two or more silane compounds with different numbers of siloxane bonds (hereinafter sometimes referred to as "silane compound-containing solution").
[0074] In addition to silica aerogel, the following can also be used as porous structures. A cohesive structure in which nanoparticles with a particle size of less than 1 μm are linked together to form a framework is also suitable. Examples of nanoparticles include fumed silica, wet silica, and those obtained by crushing or dispersing these, as well as those produced from nanoparticle sols such as colloidal silica and colloidal alumina.
[0075] In Figure 6, the porous structure powder 31 constituting the pressure-molded body consists of particles of different shapes and sizes obtained by grinding a porous structure manufactured by the sol-gel method. For the grinding process, a media-less grinding and mixing device such as a jet mill or a stirrer may be used. The porous structure takes on various shapes after grinding, but shapes other than spherical are desirable.
[0076] The average particle size of the porous structure powder 31 is preferably 30 μm or larger from the viewpoint of increasing the pore volume and improving heat insulation. Powders with an average particle size of less than 30 μm are difficult to obtain by grinding, and fine voids tend to form between the particles, which may make the press-molded product brittle. A suitable average particle size is 50 μm or larger. On the other hand, from the viewpoint of ease of molding into a sheet and suppression of particle shedding, the average particle size is preferably 150 μm or less. Powders with an average particle size exceeding 150 μm do not tend to form voids between particles, but the size of the voids tends to be large. A suitable average particle size is 120 μm or less. The average particle size of the porous structure powder is determined by the median diameter (D) obtained from the volume-based particle size distribution measured by laser diffraction / scattering. ５０ ) should be adopted.
[0077] The composition having the porous structure powder 31 may consist only of the porous structure powder 31, or it may contain other components. From the viewpoint of ensuring the desired thermal insulation performance of the thermal insulation material 21, the content of the porous structure powder in the composition shall be 65% by mass or more, preferably 70% by mass or more, when the solid content of the composition is 100% by mass. Here, the solid content refers to the components excluding volatile substances such as organic solvents and water. Other components include, for example, infrared shielding particles, inorganic fibers, dispersants, reinforcing inorganic particles, and flame retardants. Furthermore, from the viewpoint of easily achieving the desired filling state and porosity of the porous structure powder 31 in the thermal insulation material 21, which is a pressure-molded body, it is desirable that the composition does not contain a binder that binds the components of the pressure-molded body, such as the porous structure powder 31.
[0078] As shown in Figure 6, in a thermal insulation material 21 obtained by pressure molding a composition having porous structure powder 31, it is desirable that the porous structure powder 31 be in a randomly stacked form. In the thermal insulation material 21, multiple porous structure powders 31 are arranged to be stacked on top of each other.
[0079] Many of the porous structure powders 31 have shapes other than spherical, and their individual shapes and sizes differ. The packing state of the porous structure powders 31 is similar to the "nozurazumi" style found in the stone walls of Japanese castles. "Nozurazumi" is a stone masonry method in which natural stones or roughly cut stones are stacked without processing. There are small gaps 32 between the porous structure powders 31. The porous structure powders 31 come into contact with each other at points, lines, or surfaces, or a combination thereof, and there is no regularity in their arrangement. Therefore, when compressed from the outside in the thickness direction, the porous structure powders 31 move and deform by shifting from one another. In addition, because the porous structure powders 31 are elastic, they deform while generating a desired reaction force when the insulation material 21 is compressed, and return to their original shape when unloaded.
[0080] The amount of voids in the thermal insulation material 21 affects its thermal insulation properties. When the amount of voids 32 increases, i.e., the porosity increases, heat transfer due to air convection increases, thus reducing thermal insulation properties. Therefore, if only thermal insulation properties are considered, it is desirable to have no voids 32. However, if the amount of voids 32 is small, the powder 31 of the porous structure may not shift easily when compressed from the outside, potentially resulting in a smaller deformation. Conversely, if the amount of voids 32 is too large, the number of contact points formed by points, lines, and surfaces of the porous structure, or a combination thereof, decreases, making it difficult for the elasticity of the porous structure to be exhibited, potentially reducing the recovery rate. Therefore, in the thermal insulation material 21, the porosity was set to 20% or less, taking into consideration thermal insulation properties, deformability, and recovery properties. A suitable porosity is 15% or less.
[0081] 4. Effects of Spacer 4 Spacer 4 forms a sealing line 24 that seals the overlapping portion 22d of the cover 22. In the overlapping portion 22d of the cover 22, an inner member 23 is sandwiched between the first cover portion 22a and the second cover portion 22b. The sealing line 24 is formed by joining the first cover portion 22a and the inner member 23, and by joining the second cover portion 22b and the inner member 23.
[0082] In other words, the sealing wire 24 includes an inner member 23 in addition to the first cover portion 22a and the second cover portion 22b. Therefore, the bonding strength of the sealing wire 24 is improved. Furthermore, compared to the case where only the first cover portion 22a and the second cover portion 22b are bonded, the rigidity of the sealing wire 24 is increased by including the inner member 23. Therefore, the shape stability of the sealing wire 24 is improved. In this way, the sealing performance of the sealing wire 24 is improved.
[0083] Furthermore, in the battery pack 1, the sealing wire 24 is positioned opposite the bottom surface 11 of the housing 2. Here, the rigidity of the sealing wire 24 of the spacer 4 is increased by including the inner member 23, compared to the case where only the first cover portion 22a and the second cover portion 22b are joined. Because the highly rigid sealing wire 24 is positioned opposite the bottom surface 11 of the housing 2, the positioning accuracy in the height direction of the spacer 4 is improved. Since the relative position between the battery cell 3 and the spacer 4 can be made highly accurate, the heat insulation performance for the battery cell 3 can be improved.
[0084] Furthermore, the thickness of the sealing wire 24 is thinner than the thickness of the insulation material 21. Therefore, the sealing wire 24 is not subjected to compressive load from the battery cell 3. In other words, the sealing wire 24 does not affect the expansion and contraction of the battery cell 3. Moreover, the rigidity of the sealing wire 24 can be maintained.
[0085] Furthermore, the sealing wire 24 seals the overlapping portion 22d of the cover 22 by welding the first cover portion 22a to the inner member 23 and the second cover portion 22b to the inner member 23. This makes it possible to form the sealing wire 24 without using adhesives or the like.
[0086] When the sealing wire 24 is formed by welding, the inner member 23 should be made of a material with a higher melting point than the cover 22. This allows the cover 22 located on the outside to melt easily, thereby forming the sealing wire 24.
[0087] Furthermore, the thickness of the sealing wire 24 is made thinner than the thickness of the insulation material. This prevents the sealing wire 24 from being compressed by the battery cell 3. As a result, the durability of the sealing wire 24 can be improved.
[0088] Furthermore, the thickness of the inner member 23 should be greater than the thickness of the cover 22. This increases the rigidity of the sealing wire 24.
[0089] The sealing wire 24 is preferably formed to surround the perimeter of the insulation material 21. This allows for the presence of a highly rigid sealing wire 24 around the insulation material 21.
[0090] Furthermore, the inner member 23 may be positioned inside the cover 22 and serve as an inner cover that covers at least a portion of the heat insulating material 21. This allows the inner member 23 to serve both the function of increasing the rigidity of the sealing wire 24 and the function of a cover that covers the heat insulating material 21.
[0091] Furthermore, the inner member 23, which functions as an inner cover, may include a first inner cover portion 23a positioned between the thermal insulation material 21 and the first cover portion 22a, covering the first surface 21a of the thermal insulation material 21, and a second inner cover portion 23b positioned between the thermal insulation material 21 and the second cover portion 22b, covering the second surface 21b of the thermal insulation material 21. This allows the thermal insulation material 21 to be covered on both sides by a double cover.
[0092] 5. Manufacturing Method of Spacer 4 The manufacturing method of spacer 4 will be explained with reference to Figures 8 to 14.
[0093] As shown in Figure 9, the material 40 for the spacer 4 is prepared. The material 40 for the spacer 4 includes a first material 41 corresponding to the first cover portion 22a, a second material 42 corresponding to the second cover portion 22b, a third material 43 corresponding to the first inner cover portion 23a, a fourth material 44 corresponding to the second inner cover portion 23b, and an insulating material 21.
[0094] The first material 41 is formed to have a larger outer shape than the first cover portion 22a. The first material 41 is pre-shaped into a predetermined form and has a portion corresponding to the central recess of the first cover portion 22a. The second material 42 is formed to have a larger outer shape than the second cover portion 22b.
[0095] The third material 43 is formed to have a larger outer shape than the first inner cover portion 23a. The third material 43 is pre-shaped to a predetermined form and has a portion corresponding to the central recess of the first inner cover portion 23a. The fourth material 44 is formed to have a larger outer shape than the second inner cover portion 23b.
[0096] As shown in Figure 10, a heating tool 50 is prepared. The heating tool 50 includes a lower mold 51, an upper mold 52, and a heating section 53. The lower mold 51 is formed so that the material 40 of the spacer 4 can be placed on it. The upper mold 52 corresponds to the lower mold 51 and is formed in a shape that covers it. The heating section 53 is held in the upper mold 52 and protrudes downward from the lower surface of the upper mold 52. The heating section 53 is formed in a shape that corresponds to the seal line 24. However, the outer shape of the heating section 53 is formed to be larger than the seal line 24.
[0097] Then, as shown in Figures 8 and 9, the materials 40 of the spacer 4 are arranged. That is, they are arranged in the order of first material 41, third material 43, heat insulating material 21, fourth material 44, and second material 42 (S1: material arrangement step). At this time, the heat insulating material 21 is housed in the internal space 46 formed by the third material 43 and the fourth material 44, and also in the internal space 45 formed by the first material 41 and the second material 42. The internal space 45 corresponds to the internal space 22c of the cover 22. The internal space 46 corresponds to the internal space 23c of the inner member 23.
[0098] For example, the insulation material 21 is housed in a central recess of the first material 41 corresponding to the first cover portion 22a, and is covered by the second material 42 corresponding to the second cover portion 22b. Furthermore, the insulation material 21 is housed in a central recess of the third material 43 corresponding to the first inner cover portion 23a, and is covered by the fourth material 44 corresponding to the second inner cover portion 23b.
[0099] Next, as shown in Figures 8 and 11, the material 40 of the spacer 4 is placed on the heating tool 50 (S2: tool placement step). At this time, the area where the first material 41 and the second material 42 overlap, which is the periphery of the material 40 of the spacer 4, is supported by the lower mold 51. Furthermore, the area where the heat insulating material 21 is present may also be supported by the lower mold 51.
[0100] Next, as shown in Figures 8 and 12, a predetermined portion of the material 40 of the spacer 4 is sealed by heating with the heating tool 50 (S3: sealing process). As a result, a portion of the area where the first material 41 and the second material 42 overlap is heated and sealed. In other words, the portion of the area where the first material 41 and the second material 42 overlap, corresponding to the heating portion 53, is sealed by heat welding. At this time, the third material 43 and the fourth material 44, sandwiched between the first material 41 and the second material 42, are also heated and sealed. In this way, a portion corresponding to the seal line 24 is formed.
[0101] Next, as shown in Figures 8 and 13, the material 40 of the spacer 4 is removed from the heating tool 50 (S4: removal process). Subsequently, as shown in Figures 8 and 14, the outer circumference of the material 40 of the spacer 4 is cut, and the spacer 4 is completed (S5: cutting process). The cutting is performed along the portion sealed by the heating unit 53. In other words, the cutting point is the position that divides the portion sealed by the heating unit 53.
[0102] The spacer 4 can be manufactured using the described manufacturing method. Although the manufacturing method for forming the seal wire 24 by heat welding has been described, similar methods can be applied to other methods for forming the seal wire 24. Furthermore, it is not necessary to cut the outer edge of the cover 22 in the cutting step S5.
[0103] According to the above manufacturing method, the first material 41, the second material 42, the third material 43, and the fourth material 44 are sealed simultaneously by heat welding. Alternatively, an inner welded portion can be formed by first heat welding to join the third material 43 and the fourth material 44 together, and then the overlapping portion of the first material 41 and the second material 42 can be sealed by heat welding. In this case, the seal line 24 may be provided so as to overlap the inner welded portion, or it may be provided so as not to overlap the inner welded portion.
[0104] In the above manufacturing method, the sealing process S3 and the cutting process S5 were treated as separate processes. Alternatively, the cutting process S5 may be performed simultaneously with the sealing process S3. For example, the cutting process S5 by thermal cutting can be performed in conjunction with the sealing process S3, which seals the first material 41, the second material 42, the third material 43, and the fourth material 44 by thermal welding or ultrasonic welding.
[0105] (Embodiment 2) The spacer 4 in Embodiment 2 will be described with reference to Figure 15. In Embodiment 2 and later, reference numerals that are the same as those used in the previously described embodiments represent the same components as those in the previously described embodiments, unless otherwise specified.
[0106] Figure 15 corresponds to Figure 9 in Embodiment 1. In other words, Figure 15 corresponds to the material arrangement step S1 in the manufacturing method of the spacer 4 shown in Figure 8.
[0107] As shown in Figure 15, the material 40 of the spacer 4 includes a first material 41 corresponding to the first cover portion 22a, a second material 42 corresponding to the second cover portion 22b, a third material 43 corresponding to the first inner cover portion 23a, a fourth material 144 corresponding to the second inner cover portion 23b, and an insulating material 21.
[0108] The materials are arranged in the following order: first material 41, third material 43, heat insulating material 21, fourth material 144, and second material 42. The fourth material 144 has an outer shape that corresponds to the recess of the first material 41. Therefore, in the spacer 4, only the first inner cover portion 23a is sandwiched in the overlapping portion 22d between the first cover portion 22a and the second cover portion 22b.
[0109] (Embodiment 3) The spacer 4 in Embodiment 3 will be described with reference to Figure 16. Figure 16 corresponds to Figure 9 in Embodiment 1. In other words, Figure 16 corresponds to the material arrangement step S1 in the manufacturing method of the spacer 4 shown in Figure 8.
[0110] As shown in Figure 16, the material 40 of the spacer 4 includes a first material 41 corresponding to the first cover portion 22a, a second material 42 corresponding to the second cover portion 22b, a third material 43 corresponding to the first inner cover portion 23a, and an insulating material 21.
[0111] The materials are then arranged in the order of the first material 41, the third material 43, the heat insulating material 21, and the second material 42. Therefore, in the spacer 4, only the first inner cover portion 23a is sandwiched between the overlapping portion 22d of the first cover portion 22a and the second cover portion 22b.
[0112] (Embodiment 4) The spacer 4 in Embodiment 4 will be described with reference to Figure 17. Figure 17 corresponds to Figure 9 in Embodiment 1. In other words, Figure 17 corresponds to the material arrangement step S1 in the manufacturing method of the spacer 4 shown in Figure 8.
[0113] As shown in Figure 17, the material 40 of the spacer 4 includes a first material 41 corresponding to the first cover portion 22a, a second material 42 corresponding to the second cover portion 22b, a third material 243, and an insulating material 21.
[0114] The third material 243 corresponds to the portion of the third material 43 in Embodiment 1 that excludes the central recess, i.e., the outer peripheral edge portion. Therefore, the third material 243 has a through hole in the center.
[0115] The materials are arranged in the order of first material 41, insulation material 21, third material 243, and second material 42. However, the insulation material 21 and the third material 243 are in a positional relationship where they do not overlap. Therefore, in the spacer 4, only the inner member 23 corresponding to the third material 243 is sandwiched in the overlapping portion 22d between the first cover portion 22a and the second cover portion 22b.
[0116] (Other embodiments) In the above embodiment, the spacer 4 was positioned opposite the battery cell 3, which is the object of the installation. The object on which the spacer 4 is placed is not limited to the battery cell 3; the spacer 4 can be positioned opposite other objects that require thermal insulation performance.
Claims
1. A spacer positioned opposite an object, comprising: an insulating material having a first surface facing the object and a second surface which is the back surface of the first surface; a cover having a first cover portion that covers the first surface of the insulating material and a second cover portion that covers the second surface of the insulating material, the insulating material being housed in an internal space formed by the first cover portion and the second cover portion, and having an overlapping portion in which the first cover portion and the second cover portion are overlapped at least a part of the periphery; an inner member sandwiched between the first cover portion and the second cover portion at least in the overlapping portion; and a sealing line that seals the overlapping portion of the cover by joining the first cover portion and the inner member and joining the second cover portion and the inner member.
2. The spacer according to claim 1, wherein the sealing wire seals the overlapping portion of the cover by welding the first cover portion to the inner member and the second cover portion to the inner member.
3. The spacer according to claim 2, wherein the inner member is made of a material with a higher melting point than the cover.
4. The spacer according to claim 1, wherein the thickness of the sealing wire is thinner than the thickness of the insulating material.
5. The spacer according to claim 1, wherein the thickness of the inner member is greater than the thickness of the cover.
6. The spacer according to claim 1, wherein the inner member is made of a nonwoven fabric or a woven fabric.
7. The spacer according to claim 1, wherein the inner member is an inner cover disposed inside the cover and covering at least a portion of the heat insulating material.
8. The spacer according to claim 7, wherein the inner cover comprises a first inner cover portion disposed between the insulating material and the first cover portion and covering the first surface of the insulating material, and a second inner cover portion disposed between the insulating material and the second cover portion and covering the second surface of the insulating material.
9. The spacer according to claim 1, wherein the sealing wire is formed to surround the periphery of the insulating material.
10. The spacer according to claim 1, wherein the thermal insulation material is formed of a plurality of inorganic particles.
11. The spacer according to claim 1, wherein the thermal insulation material is elastic.
12. The spacer according to claim 1, wherein the object is a battery cell.
13. A method for manufacturing a spacer according to any one of claims 1 to 12, comprising: arranging an insulating material in the internal space; arranging an inner member between the first cover portion and the second cover portion at least in the overlapping portion; and forming the seal line by heating the overlapping portion.
14. A battery pack comprising: a housing including a bottom surface; a battery cell which is the object housed in the housing; and the spacer according to claim 1, which is housed in the housing and positioned opposite the battery cell, wherein the sealing wire is located opposite the bottom surface.