Method for manufacturing spacers, spacer group, and battery pack

Abstract

The objective is to provide a battery pack that can stably obtain excellent thermal insulation performance using spacers, a group of spacers used in the battery pack, and a method for manufacturing spacers. [Solution] A battery pack comprising a plurality of single cells and a plurality of sheet-like spacers arranged between the single cells, wherein the tolerance of the creepage distance A of the plurality of spacers is 0.010 to 2.0 mm. (Surface distance A) The first cell is brought close to the first planar side of the spacer, and the second cell is brought close to the second planar side of the spacer. Point a1 is the point on the edge of the contact portion where the first cell and the spacer are in surface contact, and point a2 is the point on the edge of the contact portion where the second cell and the spacer are in surface contact. Let A (mm) be the creepage distance between point a1 and point a2, which is the shortest distance along the surface of the spacer.

Description

[Technical Field]

[0001] This invention relates to a method for manufacturing spacers, a group of spacers, and a battery pack. [Background technology]

[0002] Battery modules, including secondary batteries, installed in mobile vehicles and ships, utilize battery packs that comprise multiple individual cells and spacers placed between them. For example, Patent Document 1 discloses a battery pack in which a heat conductive member (spacer) made of a resin material with a high flexural modulus is placed between single cell cells in order to suppress heat transfer to adjacent single cell cells and efficiently dissipate heat into a heat dissipation space. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2011-108617 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] However, with conventional technologies such as those described in Patent Document 1, it is difficult to obtain a battery pack that can stably achieve excellent heat insulation performance through the use of spacers.

[0005] The primary objective of this invention is to provide a method for manufacturing a spacer that can stably provide excellent thermal insulation performance, a group of spacers that can stably provide excellent thermal insulation performance, and a battery pack using the group of spacers. [Means for solving the problem]

[0006] The present invention includes the following configuration. [1] A method for manufacturing a spacer comprising an inner material and an outer material, The process includes an inner material supply step of supplying an inner material, an outer material supply step of supplying an outer material, and a sealing step of forming a laminate by sandwiching both sides of the inner material with the outer material, and sealing the outer materials around the inner material to form a sealed body. The method for manufacturing a spacer, wherein the encapsulating material supply step includes causing the encapsulating material to absorb a liquid. [2] The manufacturing method according to [1], wherein the packaging material supply step includes supplying a strip-shaped packaging material and cutting the packaging material perpendicular to the flow direction. [3] The manufacturing method according to [1] or [2], wherein the sealing step includes sealing the outer edges of a pair of exterior materials. [4] The manufacturing method according to any one of [1] to [3], wherein the sealing step includes degassing the air contained between the pair of exterior materials and sealing the outer edges of the pair of exterior materials. [5] The sealing step comprises degassing the air contained between the pair of exterior materials by reducing the pressure in the sealed space in which the laminate is present, or by pushing the laminate from the center outward, and sealing the outer edges of the pair of exterior materials, according to any one of [1] to [4]. [6] The manufacturing method according to any one of [1] to [5], further comprising a cutting step of cutting the sealing body into a rectangle after the sealing step. [7] The process further includes a cutting step of cutting the sealing body into a rectangular shape after the sealing step, A manufacturing method according to any one of [1] to [6], wherein the dimensional error of the cut rectangle is 5.0 mm or less. [8] The process further includes a cutting step of cutting the sealing body into a rectangular shape after the sealing step, A manufacturing method according to any one of [1] to [7], wherein the dimensional error of the cut rectangle is 2.0 mm or less. [9] The process further includes a cutting step of cutting the sealing body into a rectangular shape after the sealing step, A manufacturing method according to any one of [1] to [8], wherein the dimensional error of the cut rectangle is 1.0 mm or less.

[10] The process further includes a cutting step of cutting the sealing body into a rectangular shape after the sealing step, The manufacturing method according to any one of [1] to [9], wherein the position at which the sealing body is cut is adjusted based on a mark printed on the outer material.

[11] A manufacturing method according to any one of [1] to

[10] , further comprising a cutting step of cutting the sealant into a rectangular shape after the sealing step, and an inspection step of inspecting the appearance of the surface of the sealant.

[12] The process further includes a cutting step of cutting the seal into a rectangular shape after the sealing step, and an inspection step of inspecting the appearance of the surface of the seal, A manufacturing method according to any one of [1] to

[11] , which includes determining whether a product is good or defective based on the results of the inspection.

[13] The process further includes a cutting step of cutting the seal into a rectangular shape after the sealing step, and an inspection step of inspecting the appearance of the surface of the seal, The sealed products that are judged to be good quality are transported to the exit. A manufacturing method according to any one of [1] to

[12] , which includes discarding any sealed products that are determined to be defective instead of transporting them to the exit.

[14] The manufacturing method according to any one of [1] to

[13] , wherein the packaging material supply step includes supplying the packaging material having a width of 50 to 90% of the width perpendicular to the flow direction of the outer material.

[15] The manufacturing method according to any one of [1] to

[14] , wherein the encapsulating material supply step includes causing the encapsulating material to absorb water such that the water absorption rate relative to the saturation water absorption amount of the encapsulating material is 5% or more.

[16] The manufacturing method according to any one of [1] to

[15] , wherein in the encapsulating material supply step, a liquid to be absorbed by the encapsulating material is supplied from a nozzle.

[17] The manufacturing method according to any one of [1] to

[16] , wherein the encapsulating material supply step is supplied such that the position of one end of the encapsulating material in a width perpendicular to the flow direction is fixed.

[18] A group of spacers comprising multiple spacers that are sheet-like and have a rectangular shape when viewed in the thickness direction, A group of spacers, wherein the tolerance of the creepage distance A of the aforementioned multiple spacers is 0.010 to 2.0 mm. (Surface distance A) The surface distance A is defined by the following methods (1-1) and (1-2), and its tolerance is calculated from any 10 spacers. (1-1) Place the first single cell on the first plane side of the spacer and the second single cell on the second plane side of the spacer so that their planes are parallel to each other. While maintaining their surfaces parallel to each other, bring each of the first single cell and the second single cell closer to the position where they contact the spacer. (1-2) When the first single cell and the spacer are in point contact, use the contact point; when they are in surface contact, use the point on the edge of the contact portion as point a1. When the second single cell and the spacer are in point contact, use the contact point; when they are in surface contact, use the point on the edge of the contact portion as point a2. The surface distance A (mm) is the shortest distance from point a1 to point a2 along the surface of the spacer and across the short side of the spacer.

[19] The spacer group according to

[18] , wherein the tolerance of the intersection distance is 0.010 to 10 mm.

[20] A battery pack including a plurality of single cells and the spacer group according to

[18] or

[19] . [Advantages of the Invention]

[0007] According to the present invention, there are provided a method for manufacturing a spacer capable of stably obtaining excellent heat insulation performance, a spacer group capable of stably obtaining excellent heat insulation performance, and a battery pack using the spacer group. [Brief Description of the Drawings]

[0008] [Figure 1] It is a schematic cross-sectional view showing an example of a spacer manufactured by the manufacturing method according to the embodiment. [Figure 2] It is a schematic diagram for explaining an inner packaging material supply process in a method for manufacturing a spacer according to an example of the embodiment. [Figure 3] It is a schematic diagram for explaining an outer packaging material supply process and a sealing process in a method for manufacturing a spacer according to an example of the embodiment. [Figure 4]It is a schematic diagram for explaining a cutting process and an inspection process in a method for manufacturing a spacer according to an example of an embodiment. [Figure 5] It is a schematic diagram for explaining a state of degassing in a sealing process of a method for manufacturing a spacer according to an example of an embodiment. [Figure 6] It is a cross-sectional view schematically showing a battery module according to an example of an embodiment. [Figure 7] It is a schematic diagram for explaining the creepage distance A of the spacer. [Figure 8] It is a schematic diagram for explaining the creepage distance A of the spacer. [Figure 9] It is a schematic diagram for explaining the creepage distance A of the spacer. [Figure 10] It is a schematic diagram for explaining the creepage distance A of the spacer. [Figure 11] It is a diagram for explaining the distance between the intersection of the diagonal lines of the spacer and the intersection of the diagonal lines of the inner packaging material in a plan view of the spacer seen from the thickness direction.

Embodiments of the Invention

[0009] Hereinafter, some embodiments of the present invention will be described with appropriate reference to the drawings. The dimensional ratios in the drawings are for convenience of explanation and may be different from the actual ones. Also, in the drawings, the same components are denoted by the same reference numerals, and the description of overlapping components may be omitted.

[0010] [Method for Manufacturing Spacer] The method for manufacturing a spacer according to an embodiment is a method for manufacturing a spacer provided between each single cell constituting a battery module. This spacer is a member for preventing each single cell from contacting each other.

[0011] The method for manufacturing a spacer according to an embodiment includes the following inner packaging material supply process, outer packaging material supply process, and sealing process. Inner packaging material supply process: Supply the inner packaging material. Outer packaging material supply process: Supply the outer packaging material. Sealing process: A laminate is formed by sandwiching both sides of the inner material with the outer material, and the outer materials surrounding the inner material are sealed together to form a sealed body. In the method for manufacturing a spacer according to the embodiment, the encapsulating material supply step includes causing the encapsulating material to absorb a liquid.

[0012] The method for manufacturing a spacer according to this embodiment preferably includes the following cutting step after the sealing step, and more preferably includes the following inspection step. Cutting process: The sealing body is cut into a rectangular shape. Inspection process: The appearance of the sealing body is inspected.

[0013] <Spacer> Figure 1 is a schematic cross-sectional view showing an example of a spacer manufactured by the manufacturing method according to the embodiment. The example spacer 20 shown in Figure 1 comprises an inner material 22 and an outer material 24 in which the inner material 22 is contained in a sealed state. Typically, the outer edges 26 of the outer materials 24 around the inner material 22 are sealed together with the inner material 22 having a rectangular planar shape, with the inner material 22 having a rectangular planar shape positioned between two outer materials 24 having a rectangular planar shape.

[0014] Insulating material can be used as the internal encapsulant of the spacer. While insulating paper is typically used as the insulating material, it is not limited to this. The insulation material may include cotton sheets, polyimide fibers, aramid fibers, polytetrafluoroethylene (PTFE) fibers, glass fibers, rock wool, ceramic fibers, etc. The insulating material may contain particles such as silica particles, alumina particles, calcium silicate, clay minerals, vermiculite, mica, cement, perlite, fumed silica, and aerogel.

[0015] The thermal conductivity of the insulation material is preferably 0.3 W / (m·K) or less, and more preferably 0.1 W / (m·K) or less. The thermal conductivity of the insulation material can be measured by the periodic heating method described in JIS R2616. For example, heaters with controllable temperatures are installed on the upper and lower surfaces of the test piece (heat insulating material). The upper heater applies periodic temperature fluctuations in the thickness direction, and the lower heater controls the lower surface to a constant temperature. Then, the thermal diffusivity is determined from the phase difference (time difference) that occurs when the temperature fluctuation propagates from the upper surface to the intermediate surface of the test piece, and the thermal conductivity is calculated from the product of the specific heat and the density.

[0016] The density of the heat insulating material is preferably 0.23 g / cm 3 or more, more preferably 0.25 g / cm 3 or more, and even more preferably 0.28 g / cm 3 or more. If the density of the heat insulating material is not less than the lower limit value, the amount of deformation of the spacer during compression tends to be small. The density of the heat insulating material is preferably not more than 1.10 g / cm 3 or less, more preferably not more than 1.00 g / cm 3 or less, and even more preferably not more than 0.90 g / cm 3 or less. If the density of the heat insulating material is not more than the upper limit value, since there are many air layers in the internal voids, the heat insulation property tends to be good. The preferable lower limit and upper limit of the density of the heat insulating material can be arbitrarily combined. For example, 0.23 to 1.10 g / cm 3 is preferable, 0.25 to 1.00 g / cm 3 is more preferable, and 0.28 to 0.90 g / cm 3 is even more preferable.

[0017] Since the effect of suppressing the thermal runaway of the assembled battery becomes higher, the inner packaging material of the spacer is preferably composed of a heat insulating material that holds a liquid. In an assembled battery, when one of the single cells is damaged due to overcharging or internal short circuit, the surface temperature of the battery can reach several hundred degrees, and this can cause damage to spread chain-reaction throughout the entire assembled battery when it is transmitted to the surrounding single cells. However, if the heat insulating material holds a liquid, when one of the single cells generates abnormal heat, the liquid in the inner packaging material can volatilize, absorbing the heat of vaporization from the surroundings and suppressing the temperature rise.

[0018] As the liquid held in the heat insulating material, a liquid with a boiling point of 80 to 250°C at normal pressure is preferable, and a liquid with a boiling point of 100 to 150°C at normal pressure is more preferable. Examples of liquids include water, alcohols, esters, ethers, ketones, hydrocarbons, fluorinated compounds, and silicone oils, with water being preferred. The insulating material may contain only one type of liquid or two or more types. The liquid held in the insulating material may contain additives such as antifreeze agents, preservatives, and pH adjusters.

[0019] Any material that can seal the inner contents is acceptable as the outer packaging material; for example, resin sheets or metal sheets can be used. Because it is easy to obtain excellent heat resistance and strength, a laminate in which metal foil and a resin layer are laminated together is preferred as an exterior material. For example, a laminate of three or more layers including a resin layer, metal foil, and a sealant layer is an example.

[0020] Examples of metal foils include aluminum foil, copper foil, tin foil, nickel foil, stainless steel foil, lead foil, tin-lead alloy foil, bronze foil, silver foil, iridium foil, and phosphor bronze foil. Among these, aluminum foil, copper foil, and nickel foil are preferred, with aluminum foil being particularly preferred.

[0021] The resin constituting the resin layer can be at least one of a thermosetting resin and a thermoplastic resin, with thermoplastic resins being preferred. Examples of resins include olefin resins such as polyethylene and polypropylene, polystyrene, nylon, acrylic resins, epoxy resins, polyurethane, polyether ether ketone, polyethylene terephthalate, polyphenylene sulfide, polycarbonate, and aramid. Among these, polypropylene, nylon, and polyethylene terephthalate are preferred.

[0022] The thickness of the exterior material is not particularly limited and can be, for example, 5 to 200 μm. If the exterior material is a laminate, for example, the metal foil can be 3 to 50 μm thick and the resin layer 2 to 150 μm thick.

[0023] One possible configuration for housing the inner material within the outer material is to sandwich the inner material between two outer materials and seal the outer edges of the outer materials by heat fusion or adhesive. However, this is not limited to this configuration. Alternatively, one outer material may be folded to sandwich the inner material between the folds, and the outer edges of the outer material may be sealed by heat fusion or adhesive.

[0024] The width of the outer edge of the spacer is preferably 2 mm or more, more preferably 3 mm or more, and even more preferably 4 mm or more. If the width of the outer edge of the spacer is above the lower limit, sufficient peel strength can be obtained, and the amount of liquid or gas contained can be maintained for a long period of time. The width of the outer edge of the spacer is preferably 10 mm or less, more preferably 9 mm or less, and even more preferably 8 mm or less. If the width of the outer edge of the spacer is below the upper limit, functions other than sealing can be efficiently designed. The preferred lower and upper limits of the outer edge width of the spacer can be arbitrarily combined, for example, 2 to 10 mm is preferred, 3 to 9 mm is more preferred, and 4 to 8 mm is even more preferred.

[0025] The ratio of the spacer area to the area of ​​a single cell is preferably 0.8 or higher, more preferably 0.9 or higher, and even more preferably 0.95 or higher. If the ratio of the spacer area to the single cell area is above the lower limit, short circuits due to contact between single cells are less likely to occur, the pressure on the surface of the single cells becomes more uniform, and performance degradation over time tends to be less likely. The ratio of the spacer area to the single cell area is preferably 1.2 or lower, more preferably 1.1 or lower, and even more preferably 1.05 or lower. If the ratio of the spacer area to the single cell area is below the upper limit, the battery pack can be made smaller, and the battery energy density tends to be higher. The preferred lower and upper limits for the ratio of the spacer area to the single cell area can be arbitrarily combined; for example, 0.8 to 1.2 is preferred, 0.9 to 1.1 is more preferred, and 0.95 to 1.05 is even more preferred.

[0026] <Manufacturing equipment> The following describes the manufacturing apparatus used in a manufacturing method according to one example of an embodiment. Figure 2 is a schematic diagram showing the inner packaging material supply device 110 used in the inner packaging material supply process. Figure 3 is a schematic diagram showing the outer packaging material supply device 120 used in the outer packaging material supply process and the sealing device 130 used in the sealing process. Figure 4 is a schematic diagram showing the cutting device 140 used in the cutting process and the inspection device 150 used in the inspection process. One example of a spacer manufacturing method uses a spacer manufacturing apparatus 100 equipped with an internal material supply device 110, an external material supply device 120, a sealing device 130, a cutting device 140, and an inspection device 150.

[0027] As shown in Figure 2, the internal material supply device 110 includes an internal material supply means 111 for supplying long strip-shaped insulation material 22A onto a first conveyor 114, a liquid supply means 112 for supplying liquid L to the strip-shaped insulation material 22A on the first conveyor 114 supplied by the internal material supply means 111, and a cutting means 113 for cutting the strip-shaped insulation material 22A containing the liquid.

[0028] The strip-shaped insulating material 22A supplied from the internal material supply means 111 onto the first conveyor 114 is transported with its two flat surfaces parallel to the horizontal direction. The liquid supply means 112 can be any means capable of supplying liquid L to the strip-shaped insulating material 22A on the first conveyor 114, and examples include a syringe pump and a slit nozzle.

[0029] In one example shown in Figure 2, two encapsulating material supply means 111 and two liquid supply means 112 are alternately provided in the flow direction, and two layers of strip-shaped insulating material 22A containing liquid L are stacked. Furthermore, the number of internal material supply means 111 and liquid supply means 112 is not limited to two, but may be one or three or more. In other words, the configuration is not limited to two layers of strip-shaped insulating material 22A containing liquid L, but may be one layer or three or more layers. It is preferable to place an edge position controller (EPC) at the location where the strip-shaped insulation material 22A is laminated, and to control the position of the side edges of the laminated strip-shaped insulation material 22A with the EPC. This makes it possible to further reduce the tolerance of the intersection distance D, which will be described later.

[0030] The cutting means 113 is equipped with a cutting blade that cuts in a direction perpendicular to the flow direction of the strip-shaped insulation material 22A, that is, along the width direction of the strip-shaped insulation material 22A. By cutting the strip-shaped insulation material 22A at predetermined intervals with the cutting means 113, a plurality of rectangular inner materials 22 are formed sequentially. By cutting the stacked strip-shaped insulating material 22A containing liquid L all at once using the cutting means 113, the individual insulating materials constituting the inner material 22 are less likely to shift, and the tolerance of the intersection distance D, described later, can be made smaller. The cutting means 113 may also be a laser cutting method for the strip-shaped insulation material 22A.

[0031] In the internal material supply device 110, multiple internal materials 22 after cutting are transported from the first conveyor 114 to the second conveyor 115. The transport speed of the second conveyor 115 is faster than that of the first conveyor 114, so that the spacing between each internal material 22 widens as they move from the first conveyor 114 to the second conveyor 115. Compared to conveying by a robotic arm, conveying by a conveyor is less prone to misalignment of the enclosed material 22, and the tolerance of the intersection distance D, described later, can be made smaller.

[0032] The outer packaging material supply device 120 includes a first outer packaging material supply means 121 that supplies long strip-shaped outer packaging material 24A to the upper side of each inner packaging material 22 after cutting, and a second outer packaging material supply means 122 that supplies long strip-shaped outer packaging material 24A to the lower side of each inner packaging material 22.

[0033] The sealing device 130 is a device that seals the strip-shaped outer material 24A around the inner material 22 in a laminate 25 of strip-shaped outer material 24A, inner material 22, and strip-shaped outer material 24A. The sealing device 130 preferably includes a degassing means 131 for removing air present between a pair of strip-shaped outer covering materials 24A in the laminate 25, as illustrated in Figure 5. Furthermore, it is preferable that the sealing device 130 includes a sealing means 134 that seals the strip-shaped outer material 24A around the inner material 22 in the laminate 25 while the air is being removed by the degassing means 131.

[0034] The form of the sealing means 134 is not particularly limited, and for example, it may include a first sealing portion that seals both sides in the width direction of each inner material 22 in a pair of strip-shaped outer materials 24A of the laminate 25 along the flow direction (side seal), and a second sealing portion that seals between each inner material 22 in a pair of strip-shaped outer materials 24A of the laminate 25 along the width direction (end seal). The first and second sealing portions of the sealing means 134 are not particularly limited, and for example, a heat sealer can be used.

[0035] The degassing means 131 comprises a support base 132 and a vertically movable sponge body 133 positioned above the support base 132. The degassing means 131 can expel air contained mainly in the inner material 22 between the pair of strip-shaped outer materials 24A to the outside by pressing the sponge body 133 against the laminate 25 on the support base 132 from above and compressing it.

[0036] By using the degassing means 131 during sealing with the sealing device 130, degassing can be easily performed without creating a vacuum around the laminate 25. Furthermore, compared to creating a vacuum around the laminate 25, the processing speed is improved, and it is easier to accommodate changes in the size of the desired spacer. In addition, the degassing state inside the laminate 25 can be easily changed by changing the pressure when compressing the laminate 25 with the sponge body 133. Furthermore, by pressing the encapsulating material 22 of the laminate 25 with the sponge body 133 while sealing, the displacement of the encapsulating material 22 during sealing can be suppressed, thereby making the tolerance of the intersection distance D, described later, smaller.

[0037] In the sealed body 28 after sealing by the sealing device 130, multiple encapsulating materials 22 are individually sealed at predetermined intervals in the flow direction. The cutting device 140 is a device that cuts the sealing portion around the encapsulating material 22 in a typically rectangular shape from the sealed body 28, thereby punching out the spacers 20. The cutting device 140 can be any device that can punch out multiple spacers 20 from the sealed body 28, such as a Thomson die or a die. The cutting device 140 may also cut the sealing portion around the encapsulating material 22 in the sealed body 28 using a laser.

[0038] The cutting device 140 preferably has a mechanism for adjusting the position of each spacer 20 when punching them out from the sealing body 28, using alignment marks pre-printed on the strip-shaped outer material 24A. By providing such a position adjustment mechanism, the dimensional accuracy of the resulting spacers 20 is improved. Furthermore, the cutting device 140 may be equipped with means for creating ear holes around the outer edge of the inner material 22 when punching out each spacer 20 from the sealing body 28.

[0039] The inspection device 150 inspects the external shape and appearance of each spacer 20 obtained by cutting the sealing body 28, and separates defective products from the finished products by sending them to the waste course. An example of an inspection device 150 is a device that includes a light irradiation means for irradiating light from various angles onto the surface of the portion of the spacer 20 in which the internal material 22 is housed, an imaging means for photographing the surface of the portion of the spacer 20 in which the internal material 22 is housed, and a determination means for analyzing the captured image to determine whether or not there are wrinkles.

[0040] The location at which the spacers 20 deemed defective are sent to the waste course is not particularly limited; they may be sent from the inspection device 150 to the waste course, or they may be sent to a waste course that branches off downstream of the inspection device 150.

[0041] <Manufacturing method> The following describes an example of a method for manufacturing a spacer according to the embodiment, using the manufacturing apparatus 100 described above.

[0042] (Inner material supply process) The encapsulating material supply process is a process of supplying encapsulating material, and preferably includes supplying a long strip of insulating material, impregnating the strip of insulating material with a liquid, preferably water, stacking the strips of insulating material, and cutting the stacked strips of insulating material perpendicular to the flow direction to form single-sheet encapsulating material. It may also include supplying the encapsulating material with one end fixed in position in a width perpendicular to its flow direction.

[0043] For example, in the example shown in Figure 2, in the internal material supply device 110, the internal material supply means 111 supplies a long strip of insulation material 22A unwound from a raw material roll onto the first conveyor 114, and the liquid supply means 112 drips liquid L onto the strip of insulation material 22A. Furthermore, the internal material supply means 111 further supplies the long strip of insulation material 22A unwound from a raw material roll onto the strip of insulation material 22A containing liquid L to stack them, and the liquid supply means 112 drips liquid L onto the upper strip of insulation material 22A. This makes it possible to stack strips of insulation material 22A containing liquid L.

[0044] In a preferred example, insulating paper is used as the strip-shaped insulating material 22A. For example, an insulating paper roll with a predetermined width is used as the raw material roll, and the strip-shaped insulating paper is supplied as the strip-shaped insulating material 22A. In addition, insulating materials other than the insulating paper described above in the spacer may be used as the strip-shaped insulating material 22A. The width of the strip-shaped insulation material 22A can be set appropriately according to the product size. By matching the width of the strip-shaped insulation material 22A to the width of the inner material 22 of the spacer 20 product, and by not performing width adjustment by cutting on the manufacturing line, the positional displacement of the inner material 22 within the spacer 20 can be reduced, thereby making the tolerance of the intersection distance D described later smaller. In one example, it is preferable to supply a strip-shaped insulation material 22A having a width of 50 to 90% of the width of the strip-shaped exterior material 24A perpendicular to the flow direction.

[0045] In a preferred example, water is used as the liquid L. The water absorption rate referred to below is the ratio of the amount of water absorbed by the encapsulating material to the saturation water absorption capacity of the encapsulating material, which is set to 100%. The higher the water absorption rate, the less likely the position of each inner material 22 formed by cutting the strip-shaped insulating material 22A described later will shift on the conveyor during transport. Therefore, the tolerance of the intersection distance D can be made smaller. In a preferred example, the water absorption rate of the insulating paper is preferably 5% or more, more preferably 10% or more, and even more preferably 15% or more. If the water absorption rate of the insulating paper is above the lower limit, the presence of liquid at the interface between the outer material and the insulating paper provides adhesion, making it possible to transport and seal without shifting position. The water absorption rate of the insulating paper is preferably 100% or less, more preferably 98% or less, and even more preferably 95% or less. If the water absorption rate of the insulating paper is below the upper limit, it is possible to transport and degas without spilling liquid from the insulating material, making it possible to seal without liquid passing through the sealing part. The preferred lower and upper limits of the water absorption rate of the insulating paper can be arbitrarily combined, for example, 5 to 100% is preferred, 10 to 98% is more preferred, and 15 to 95% is even preferred.

[0046] For example, by employing a nozzle, preferably a slit nozzle, in the liquid supply means 112, the water absorption rate of the insulating paper can be stably adjusted to a predetermined value. From the viewpoint of uniform water absorption, it is preferable that the nozzle be positioned perpendicular to the flow direction. The water absorption rate of the insulating paper can be adjusted, for example, by changing the slit width of the slit nozzle. Furthermore, instead of water, liquid L may be a liquid other than water as described in the spacer section above.

[0047] The number of layers of the strip-shaped insulation material 22A is not limited to 2, as long as the inner material 22 can be made to a predetermined thickness. The number of layers of the strip-shaped insulation material 22A can be, for example, 1 to 6, 1 to 4, 1 to 3, or 1 to 2.

[0048] The positional misalignment in the width direction between the stacked strip-shaped insulation materials 22A is preferably within 1 mm. When stacking three or more strip-shaped insulation materials 22A, it is preferable that the positional misalignment between all of them is within 1 mm. This makes it possible to further reduce the tolerance of the intersection distance D described later.

[0049] It is preferable to control the position of the side edges of the stacked strip-shaped insulation material 22A using an edge position controller (EPC). This allows for stable control of the widthwise positional misalignment between the stacked strip-shaped insulation material 22A to within 1 mm, and further reduces the tolerance of the intersection distance D described later.

[0050] The stacked strip-shaped insulation material 22A is intermittently cut at predetermined intervals by the cutting means 113 in a direction perpendicular to its flow direction, i.e., along the width direction of the strip-shaped insulation material 22A. This sequentially forms a plurality of rectangular inner materials 22. By cutting the stacked strip-shaped insulation material 22A containing the liquid L all at once, the individual insulation materials constituting the inner material 22 are less likely to shift, and the tolerance of the intersection distance D described later can be made smaller. When cutting with the cutting means 113, it is preferable to perform the cutting so that the cut surface is as perpendicular as possible to the plane of the strip-shaped insulation material 22A. The deviation in the length of each internal material 22 in the flow direction is preferably within 1 mm. This allows for a smaller tolerance for the intersection distance D, which will be described later.

[0051] After cutting, the transport speed of the second conveyor 115 is set to be faster than the transport speed of the first conveyor 114, thereby widening the spacing between the multiple internal materials 22 after cutting. By adjusting the difference between the transport speeds of the second conveyor 115 and the first conveyor 114, the spacing between each internal material 22 can be freely adjusted. By adjusting the spacing between each internal material 22, the processing speed can be improved.

[0052] (Outer packaging material supply process) For example, as shown in Figure 3, in the outer packaging material supply device 120, the first outer packaging material supply means 121 supplies long strip-shaped outer packaging material 24A unwound from the raw material roll to the upper side of each inner packaging material 22 that has been cut and is being transported. The second outer packaging material supply means 122 supplies long strip-shaped outer packaging material 24A unwound from the raw material roll to the lower side of each inner packaging material 22 that is being transported. As a result, a laminate 25 is obtained in which the strip-shaped outer packaging material 24A, inner packaging material 22, and strip-shaped outer packaging material 24A are stacked.

[0053] As for the strip-shaped exterior material 24A, one embodiment is to use an exterior material roll with a predetermined width as the raw material roll, and to supply the strip-shaped exterior material from the raw material roll. As the exterior material, the exterior material described above in the spacer section can be used. The width of the strip-shaped insulation material 22A can be set appropriately according to the product size.

[0054] At least one surface of a pair of strip-shaped outer materials 24A, preferably the upper surface of the strip-shaped outer material 24A supplied above each inner material 22, may have pre-printed registration marks for positioning during the sealing process and alignment marks for positioning during the cutting process. By using these marks for positioning during the sealing and cutting processes, the dimensional accuracy of the resulting spacer 20 can be improved, and the tolerances for creepage distance A and intersection distance D, described later, can be reduced.

[0055] (Sealing process) In the sealing process, in the laminate 25 in which each inner material 22 is sandwiched between strip-shaped outer materials 24A, the outer edges around each inner material 22 of the pair of strip-shaped outer materials 24A are sealed to form a sealed body 28. In the sealing process using the sealing device 130, it is preferable to remove the air between the pair of strip-shaped outer materials 24A in the laminate 25 using the degassing means 131 illustrated in Figure 5. Then, while degassing with the degassing means 131, it is preferable to seal the strip-shaped outer materials 24A around the inner material 22 in the laminate 25.

[0056] More specifically, the degassing means 131 compresses the laminated body 25, which has been transported onto the support stand 132, by pressing the sponge body 133A against it from above. At this time, by pushing the laminated body 25 from its center outwards, the air contained between the pair of strip-shaped outer materials 24A, mainly contained in the inner material 22, can be discharged to the outside. By performing degassing by compression with the sponge body 133, degassing can be easily performed without creating a vacuum around the laminated body 25, and the processing speed is also improved. Furthermore, it is easy to accommodate changes in the size of the target spacer, and the degassing state can be easily adjusted by changing the pressure during compression.

[0057] In addition, during the sealing process, degassing may be performed by sealing the area around the laminate 25 and reducing the pressure within the sealed space in which the laminate 25 is located. That is, the sealing process may include sealing the pair of degassed outer materials by reducing the pressure within the sealed space of the laminate, or by pushing the laminate from the center outwards.

[0058] More specifically, the degassing means 131 seals the laminated body 25, which has been transported onto the support base 132, by sandwiching it from above and below with the mold 133B, and then depressurizes the sealed space with a rotary pump. At this time, by providing a step to make tiny holes in the strip-shaped outer material 24A before the sandwiching step, it becomes easier to depressurize the space and the inside of the laminated body 25. In addition, the degassing state can be easily adjusted by changing the pump output and depressurization time during depressurization.

[0059] Furthermore, while degassing is performed using a pump by the degassing means 131, the sealing mold of the sealing means 134 simultaneously seals all four sides of each inner material 22 in the width direction and flow direction of the pair of strip-shaped outer materials 24A of the laminate 25. While the four sides are being sealed, the mold 133B is restored to pressure, and after a predetermined sealing time has elapsed, the upper and lower molds are separated. This forms a sealed body 28 in which the interior containing the inner material 22 is sufficiently degassed. It is preferable that the pair of strip-shaped outer covering materials 24A be sealed by heating, i.e., by heat sealing.

[0060] Furthermore, while degassing is performed by the degassing means 131, the first and second sealing portions of the sealing means 134 seal both sides in the width direction of each encapsulating material 22 in the pair of strip-shaped outer materials 24A of the laminate 25 along the flow direction (side seal), and seal the space between each encapsulating material 22 in the pair of strip-shaped outer materials 24A of the laminate 25 along the width direction (end seal). As a result, a sealed body 28 is formed in which the interior containing the encapsulating material 22 is sufficiently degassed. It is preferable that the pair of strip-shaped outer covering materials 24A be sealed by heating, i.e., by heat sealing.

[0061] By performing side seals and end seals in stages, it is possible to easily accommodate changes in the size of the target spacer 20.

[0062] In the sealing process, it is preferable to adjust the sealing position of the side seals and end seals while reading the registration marks pre-printed on the surface of the strip-shaped outer material 24A. This improves sealing accuracy, allowing for smaller tolerances for the creepage distance A or intersection distance D of the resulting spacer 20, as described later.

[0063] (cutting process) For example, the cutting device 140 cuts the sealing portion around each inner material 22 in the sealed body 28 into a rectangular shape, thereby sequentially manufacturing multiple spacers 20. In the cutting process, the dimensional error of the rectangle to be cut is preferably 5.0 mm or less, more preferably 2.0 mm or less, even more preferably 1.5 mm or less, particularly preferably 1.0 mm or less, and especially preferably 0.5 mm or less. When cutting with a guillotine cutter, the dimensional error of the rectangle can be reduced to 1.5 mm or less, and when cutting by punching, it is possible to cut with an accuracy of 0.5 mm or less. These measures make it possible to reduce the tolerance of the creepage distance A or intersection distance D of the resulting spacer 20, as described later.

[0064] In the cutting process, when punching out each spacer 20 from the sealing body 28, it is preferable to adjust the cutting position based on the marks printed on the strip-shaped outer material 24A. This improves the dimensional accuracy of the resulting spacer 20 and allows for smaller tolerances for the creepage distance A or intersection distance D, as described later. Furthermore, during the cutting process, when punching out each spacer 20 from the sealing body 28, ear holes may be made on the outer edge around the encapsulating material 22.

[0065] (Inspection process) For example, the inspection device 150 inspects the appearance of the sealed body after cutting, i.e., each spacer 20 punched out from the sealed body 28. Spacers 20 that are determined to be defective are removed and separated from the product. Thus, the inspection process may include determining and discarding spacers with a defective appearance (defective products) based on the judgment result.

[0066] More specifically, for example, light is shone from various angles onto the front and back surfaces of the portion of the spacer 20 containing the internal material 22, and the shape of the portion of the spacer 20 containing the internal material 22 is captured. By combining multiple images shone with light from different angles, shadows can be minimized, and a contrast close to the actual shape can be obtained. Furthermore, by appropriately adjusting the camera position, aperture value, and focus, it is possible to adjust the image quality to suit the inspection. Then, the images obtained from the capture are evaluated using a set algorithm to determine the presence or absence of wrinkles and any misalignment of the inner material 22 on the front and back surfaces of the spacer 20 where the inner material is contained. Based on the results, defective products and products are sorted accordingly. Parameters used for sorting include, for example, the difference in brightness, i.e., the difference in shade, which is used to measure the presence or absence of wrinkles and any misalignment. It is also possible to detect the size of the wrinkles by measuring the detected area. Regarding the misalignment of the inner material, the distance between the ends of the inner material and the distance between the outer edge and the end of the inner material are measured from the shade difference information mentioned above, and defective products and products are determined based on specified values. The sealed products determined to be good can be transported to the exit, while the sealed products determined to be defective can be disposed of without being transported to the exit. In the inspection process, for example, if there are wrinkles of 1 cm or more in length on the surface of the portion of the spacer 20 in which the internal material 22 is housed, it can be determined that there is a defect in appearance.

[0067] [Battery pack] An example of a battery pack according to this embodiment comprises a plurality of individual cells and a group of spacers. The group of spacers includes a plurality of sheet-like spacers with a rectangular shape when viewed from the thickness direction. Each spacer constituting the group of spacers is placed between each individual cell. Figure 6 is a schematic diagram showing a battery pack 1 of an example embodiment. The battery pack 1 comprises a housing 30, a plurality of individual cells 10 housed within the housing 30, and a plurality of sheet-like spacers 20 arranged between each individual cell 10. The housing 30 comprises a bottom plate 30a and cylindrical side walls 30b rising from the periphery of the bottom plate 30a. Inside the housing 30, multiple single cells 10 are arranged in the thickness direction, and spacers 20 are placed between the single cells 10. In the example battery pack 1 shown in Figure 6, spacers 20 are also placed between the top surface of the bottom plate 30a of the housing 30 and each single cell 10, but the configuration is not limited to this.

[0068] The spacer 20 is a component that is placed between each individual cell 10 that makes up the battery pack 1, so that the individual cells 10 do not come into contact with each other. Even if the individual cells 10 that make up the battery pack 1 expand during use, the expansion pressure is absorbed by the flexible spacer 20. In addition, the heat insulating effect of the spacer 20 makes it difficult for heat to be transferred to adjacent individual cells 10. Therefore, even if one of the individual cells 10 is damaged due to overcharging or an internal short circuit and its surface temperature becomes excessively high, the damage is prevented from spreading to the surrounding individual cells 10 in a chain reaction, thereby suppressing thermal runaway of the battery pack 1.

[0069] For example, as shown in Figure 1, the spacer 20 comprises an inner material 22 and an outer material 24 in which the inner material 22 is housed in a sealed state. Typically, the spacer 20 is constructed by placing an inner material 22 with a rectangular planar shape between two outer materials 24 with a rectangular planar shape, and sealing the outer edges 26 of the outer materials 24 around the inner material 22.

[0070] In the example shown in Figure 6, spacers 20 are stacked between each cell 10, but it is not necessary to place spacers 20 between all cell 10; it is sufficient to place a spacer between at least one cell.

[0071] <Spacer group> Multiple spacers can be stored, transported, and sold as a group of spacers before being placed between each individual cell. In the spacer group according to the embodiment, the multiple spacers have a creepage distance A tolerance of 0.010 to 2.0 mm, which is determined by the method described later. If the creepage distance A tolerance is within the above range, excellent thermal insulation performance can be stably obtained by the spacers. The tolerance of the creepage distance A of the multiple spacers in the spacer group according to the embodiment is preferably 0.010 to 1.0 mm, and more preferably 0.010 to 0.50 mm.

[0072] (Tolerance for creepage distance A) The creepage distance A is defined by the following methods (1-1) and (1-2), and its tolerance is calculated from any 10 spacers. (1-1) Place the first single cell on the first planar side of the spacer and the second single cell on the second planar side of the spacer so that their planes are parallel to each other, and while maintaining the parallelism of their planes, bring the first single cell and the second single cell closer together to a position where they contact the spacer. (1-2) If the first cell unit and the spacer are in point contact, the point at the contact point is defined as point a1; if they are in surface contact, the point on the edge of the contact portion is defined as point a2; if the second cell unit and the spacer are in point contact, the point at the contact point is defined as point a2; if they are in surface contact, the point on the edge of the contact portion is defined as point a2; and the creepage distance that is shortest when traveling along the spacer and across the short side of the spacer from point a1 to point a2 is defined as A (mm).

[0073] In step (1-1), as shown in Figure 7, the first cell 10A is placed on the first plane 20a side of the spacer 20 and the second cell 10B is placed on the second plane 20b side of the spacer 20 so that their planes are parallel to each other. While maintaining the parallelism of their planes, the first cell 10A and the second cell 10B are brought closer to the spacer 20 so that they are in contact with it. The example shown in Figure 7 is one in which the spacer 20 and the first cell 10A are in surface contact, and the spacer 20 and the second cell 10B are in surface contact.

[0074] In this example, in step (1-2), point a1 is defined as the point on the edge of the contact area between the first cell 10A and the spacer 20, and point a2 is defined as the point on the edge of the contact area between the second cell 10B and the spacer 20. Then, as shown in Figures 7 and 8, the creepage distance (length of the dashed line in Figure 4) that is the shortest distance to reach points a1 and a2 along the surface of the spacer 20 and across the short side of the spacer is determined and defined as A (mm). Typically, points a1 and a2, which are the points with the shortest distance along the surface of the spacer 20, are located on the same short side of the spacer 20 within the same cross-section obtained by cutting the spacer 20 in the thickness direction. Similarly, determine the creepage distance A for any 10 spacers and calculate their tolerances.

[0075] The example shown in Figure 9 illustrates that in step (1-1), when the first cell 10A and the second cell 10B are brought close enough to contact the spacer 20, the spacer 20 and the first cell 10A make point contact in a cross-section of the spacer 20 cut in the thickness direction, while the spacer 20 and the second cell 10B make surface contact. For example, if there are irregularities such as wrinkles on the first plane 20a of the spacer 20, this type of contact configuration may occur.

[0076] In this example, in step (1-2), the contact point between the first cell 10A and the spacer 20 is defined as point a1, and the point on the edge of the contact portion between the second cell 10B and the spacer 20 is defined as point a2. If there are multiple contact points between the first cell 10A and the spacer 20, the contact point closest to the outer edge of the spacer 20 is defined as point a1. Then, as shown in Figures 9 and 10, the creepage distance (length of the dashed line in Figure 10) that is the shortest distance along the surface of the spacer 20 and across the short side of the spacer to reach points a1 and a2 is determined and defined as A (mm). Typically, point a2, which is the shortest distance along the surface of the spacer 20, is located on the short side closest to point a1 on the spacer 20 within the same cross-section obtained by cutting the spacer 20 in the thickness direction. Similarly, determine the creepage distance A for any 10 spacers and calculate their tolerances.

[0077] In step (1-1), when the first cell 10A and the second cell 10B are brought close to the spacer 20, the creepage distance A is determined in the same manner even in the case where the spacer 20 and the first cell 10A make point contact in a cross-section obtained by cutting the spacer 20 in the thickness direction, and the spacer 20 and the second cell 10B also make point contact.

[0078] In this example, in step (1-2), the contact point between the first cell 10A and the spacer 20 is defined as point a1, and the contact point between the second cell 10B and the spacer 20 is defined as point a2. Then, the creepage distance between point a1 and point a2 that is the shortest distance along the surface of the spacer 20 is calculated and defined as A (mm). If there are multiple contact points between the first cell 10A and the spacer 20, and multiple contact points between the second cell 10B and the spacer 20, the contact points that are the shortest distance along the surface of the spacer 20 are selected as points a1 and a2. Similarly, determine the creepage distance A for any 10 spacers and calculate their tolerances.

[0079] The tolerance of creepage distance A tends to increase in step (1-1) if at least one of the contacts between the first cell and the spacer, and the contact between the second cell and the spacer, becomes a point contact due to irregularities such as wrinkles on the spacer surface. Therefore, it is preferable that the battery pack according to the embodiment includes spacers that are free of irregularities such as wrinkles on the surface, so that all 10 spacers arbitrarily selected when determining the creepage distance A make surface contact between the first cell and the spacer, and also make surface contact between the second cell and the spacer.

[0080] (Tolerance for intersection distance) In the battery pack according to the above embodiment, it is preferable that the tolerance of the distance between the intersection of the diagonals of the spacer and the intersection of the diagonals of the encapsulating material (hereinafter also referred to as "intersection distance D") in a plan view of the spacer from the thickness direction is 0.010 to 10 mm. Figure 11 is a plan view illustrating, for convenience, the case where the position of the internal material 22 in the spacer 20 is misaligned. When the intersection of the diagonals of the rectangular spacer 20, i.e., the diagonals of the rectangular exterior material 24, is taken as point a, and the intersection of the diagonals of the rectangular internal material 22 is taken as point b, the intersection distance D is the distance between point a and point b. The tolerance of the intersection distance D is calculated from any 10 spacers.

[0081] If the tolerance of the intersection distance D is within the aforementioned range, excellent thermal insulation performance can be reliably obtained with the spacer. The tolerance of the intersection distance D of the multiple spacers in the battery pack according to the embodiment is preferably 0.010 to 5.0 mm, and more preferably 0.010 to 2.5 mm.

[0082] <Single cell> Examples of single cells include lithium-ion secondary batteries, which have a positive electrode and a negative electrode capable of intercalating and releasing lithium ions, as well as an electrolyte. Other types of secondary batteries, such as lithium-ion solid-state batteries, nickel-metal hydride batteries, nickel-cadmium batteries, and lead-acid batteries, can also be used as single cells.

[0083] The applications of the battery pack are not particularly limited, and it can be applied to battery packs installed in electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric heavy machinery, electric motorcycles, electric assist bicycles, ships, aircraft, trains, uninterruptible power supplies, home energy storage systems, and battery storage systems for stabilizing power grids using renewable energy.

[0084] However, the present invention is not limited to the embodiments described above. For example, instead of using strip-shaped insulation material or strip-shaped exterior material, a spacer may be manufactured by using single-sheet insulation material and single-sheet exterior material, and then carrying out the internal material supply process, exterior material supply process, and sealing process. In this case, the dimensions may be adjusted by cutting one or two sides of the outer edge of the sealed body after the sealing process. Furthermore, without departing from the spirit of the present invention, the components in the above embodiments may be replaced with well-known components as appropriate, and the above-described modifications may be combined as appropriate. [Explanation of Symbols]

[0085] 1 battery pack 10 single batteries 10A Single Cell 10B Second Cell 20 Spacers 20a First Plane 20b Second Plane 22 Inner materials 22A Strip-shaped insulation material 24 Exterior materials 26 Outer edge 30 cabinets 100 Spacer Manufacturing Equipment 110 Inner packaging material supply device 111 Internal material supply means 112 Liquid supply means 120 Outer packaging material supply device 121 First exterior material supply means 122 Second exterior material supply means 130 Sealing device 131 Degassing method 140 Cutting device 150 Inspection devices

Claims

1. A method for manufacturing a spacer comprising an internal material and an external material, The process includes an inner material supply step of supplying an inner material, an outer material supply step of supplying an outer material, and a sealing step of forming a laminate by sandwiching both sides of the inner material with the outer material, and sealing the outer materials around the inner material to form a sealed body. The method for manufacturing a spacer, wherein the encapsulating material supply step includes causing the encapsulating material to absorb a liquid.

2. The manufacturing method according to claim 1, wherein the encapsulating material supply step includes supplying a strip-shaped encapsulating material and cutting the encapsulating material perpendicular to the flow direction.

3. The manufacturing method according to claim 1, wherein the sealing step includes sealing the outer edges of a pair of exterior materials.

4. The manufacturing method according to claim 1, wherein the sealing step includes degassing the air contained between the pair of exterior materials and sealing the outer edges of the pair of exterior materials.

5. The manufacturing method according to claim 1, wherein the sealing step includes degassing the air contained between the pair of exterior materials by reducing the pressure in the sealed space in which the laminate exists, or by pushing the laminate from the center outward, and sealing the outer edges of the pair of exterior materials.

6. The manufacturing method according to claim 1, further comprising a cutting step of cutting the sealing body into a rectangle after the sealing step.

7. The process further includes a cutting step of cutting the sealing body into a rectangular shape after the sealing step, The manufacturing method according to claim 1, wherein the dimensional error of the cut rectangle is 5.0 mm or less.

8. The process further includes a cutting step of cutting the sealing body into a rectangular shape after the sealing step, The manufacturing method according to claim 1, wherein the dimensional error of the cut rectangle is 2.0 mm or less.

9. The process further includes a cutting step of cutting the sealing body into a rectangular shape after the sealing step, The manufacturing method according to claim 1, wherein the dimensional error of the cut rectangle is 1.0 mm or less.

10. The process further includes a cutting step of cutting the sealing body into a rectangular shape after the sealing step, The manufacturing method according to claim 1, wherein the sealing body is cut at a position based on a mark printed on the outer material.

11. The manufacturing method according to claim 1, further comprising a cutting step of cutting the sealing body into a rectangular shape after the sealing step, and an inspection step of inspecting the appearance of the surface of the sealing body.

12. The process further includes a cutting step of cutting the sealing body into a rectangular shape after the sealing step, and an inspection step of inspecting the appearance of the surface of the sealing body. The manufacturing method according to claim 1, which includes determining whether a product is good or defective based on the results of the inspection.

13. The process further includes a cutting step of cutting the sealing body into a rectangular shape after the sealing step, and an inspection step of inspecting the appearance of the surface of the sealing body. The sealed products that are judged to be good quality are transported to the exit. The manufacturing method according to claim 1, further comprising discarding sealed products that are determined to be defective instead of transporting them to the exit.

14. The manufacturing method according to claim 1, wherein the encapsulating material supply step includes supplying the encapsulating material having a width of 50 to 90% of the width perpendicular to the flow direction of the outer material.

15. The manufacturing method according to claim 1, wherein the encapsulating material supply step includes causing the encapsulating material to absorb water such that the water absorption rate relative to the saturation water absorption amount of the encapsulating material is 5% or more.

16. The manufacturing method according to claim 1, wherein in the encapsulating material supply step, a liquid to be absorbed by the encapsulating material is supplied from a nozzle.

17. The manufacturing method according to claim 1, wherein the encapsulating material supply step includes supplying the encapsulating material with one end fixed in a width perpendicular to the flow direction.

18. A group of spacers comprising multiple spacers that are sheet-like and have a rectangular shape when viewed from the thickness direction, A group of spacers wherein the tolerance of the creepage distance A of the aforementioned multiple spacers is 0.010 to 2.0 mm. (Surface distance A) The creepage distance A is defined by the following methods (1-1) and (1-2), and its tolerance is calculated from any 10 spacers. (1-1) Place the first single cell on the first planar side of the spacer and the second single cell on the second planar side of the spacer so that their planes are parallel to each other, and while maintaining the parallelism of their planes, bring the first single cell and the second single cell closer together to a position where they contact the spacer. (1-2) If the first cell unit and the spacer are in point contact, the point at the contact point is defined as point a1; if they are in surface contact, the point on the edge of the contact portion is defined as point a2; if the second cell unit and the spacer are in point contact, the point at the contact point is defined as point a2; if they are in surface contact, the point on the edge of the contact portion is defined as point a2; and the creepage distance (mm) is defined as the shortest distance from point a1 to point a2 along the surface of the spacer and across the short side of the spacer.

19. The spacer group according to claim 18, wherein the tolerance of the intersection distance is 0.010 to 10 mm.

20. A battery pack comprising a plurality of single cells and a group of spacers as described in claim 18 or 19.

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