Method for manufacturing spacer, spacer group, and battery pack

Abstract

Provided is a method for manufacturing a spacer that yields a spacer capable of stably achieving excellent thermal insulation performance. Provided is a method for manufacturing a spacer that comprises a filling material and outer covering materials, said method comprising: a step of supplying the filling material; a step of supplying the outer covering materials; and a sealing step of forming a laminate in which both sides of the filling material are sandwiched between the outer covering materials, and sealing the outer covering materials around the filling material to form a sealed body. The step of supplying the filling material includes causing the filling material to absorb liquid.

Description

Method for manufacturing spacers, spacer group, and battery pack

[0001] The present invention relates to a method for manufacturing spacers, a group of spacers, and a battery pack. This application claims priority based on Japanese Patent Applications No. 2024-205788, 2024-205789, and 2024-205790, filed in Japan on November 26, 2024, the contents of which are incorporated herein by reference.

[0002] Battery modules, including secondary batteries, mounted on mobile objects such as vehicles and ships, utilize battery packs comprising multiple single cells and spacers placed between them. For example, Patent Document 1 discloses a battery pack in which heat conductive members (spacers) made of a resin material with a high flexural modulus are placed between single cell cells to suppress heat transfer to adjacent single cell cells and efficiently dissipate heat into a heat dissipation space.

[0003] Japanese Patent Publication No. 2011-108617

[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.

[0006] One embodiment of the present invention includes the following configuration: [1] A method for manufacturing a spacer comprising an inner material and an outer material, comprising: 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, wherein the inner material supply step includes causing the inner material to absorb a liquid. [2] The manufacturing method according to [1], wherein the inner material supply step includes supplying a strip-shaped inner material and cutting the inner 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 outer materials. [4] The manufacturing method according to any one of [1] to [3], wherein the sealing step includes degassing air contained between a pair of outer materials and sealing the outer edges of the pair of outer materials. [5] The manufacturing method according to any one of [1] to [4], 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 any one of [1] to [5], further comprising a cutting step of cutting the seal into a rectangle after the sealing step. [7] The manufacturing method according to any one of [1] to [6], further comprising a cutting step of cutting the seal into a rectangle after the sealing step, wherein the dimensional error of the cut rectangle is greater than 2.0 mm and less than or equal to 5.0 mm. [8] The manufacturing method according to any one of [1] to [7], further comprising a cutting step of cutting the seal into a rectangle after the sealing step, wherein the dimensional error of the cut rectangle is greater than 1.0 mm and less than or equal to 2.0 mm. [9] The manufacturing method according to any one of [1] to [8], further comprising a cutting step of cutting the seal into a rectangle after the sealing step, wherein the dimensional error of the cut rectangle is less than or equal to 1.0 mm.

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

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

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

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

[11] , further comprising a cutting step of cutting the seal into a rectangle after the sealing step, and an inspection step of inspecting the appearance of the surface of the seal, and further comprising determining whether the product is good or defective based on the result of the inspection.

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

[12] , further comprising a cutting step of cutting the seal into a rectangle after the sealing step, and an inspection step of inspecting the appearance of the surface of the seal, and further comprising transporting the seal determined to be good to the exit, and discarding the seal determined to be defective without transporting it to the exit.

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

[13] , wherein the inner material supply step comprises supplying the inner 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, the 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 includes supplying the encapsulating material with one end fixed in a width perpendicular to its flow direction.

[18] A spacer group comprising a plurality of sheet-like spacers having a rectangular shape when viewed from the thickness direction, wherein each spacer consists of an encapsulating material having a rectangular planar shape and an outer material having a rectangular planar shape in which the encapsulating material is contained in a sealed state, and the tolerance of the distance between the intersection of the diagonals of the spacer and the intersection of the diagonals of the encapsulating material in a planar view of the spacer from the thickness direction is 0.010 to 10 mm.

[19] The spacer group according to

[18] , wherein the tolerance of the creepage distance A of the plurality of spacers is 0.010 to 2.0 mm. (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) The first single cell is placed on the first planar side of the spacer, and the second single cell is placed on the second planar side of the spacer, with their planes parallel to each other. While maintaining the parallelism of their planes, the first single cell and the second single cell are brought closer to the spacer. (1-2) If the first single cell 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 a1. If the second single cell 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. The creepage distance A (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.

[20] The spacer group according to

[18] or

[19] , wherein the tolerance of the creepage distance B of the plurality of spacers is 0.010 to 2.0 mm. (Creepage distance B) Creepage distance B is defined by the following methods (2-1) and (2-2), and its tolerance is calculated from any 10 spacers. (2-1) A first cell is placed on the first planar side of the spacer, and a second cell is placed on the second planar side of the spacer, with their planes parallel to each other. A pressure of 0.1 MPa is applied from the thickness direction by the first and second cells to sandwich the spacer and bring it into surface contact with the first and second cells. (2-2) Point a1 is the point on the edge of the contact portion between the first cell and the spacer, and point a2 is the point on the edge of the contact portion between the second cell and the spacer. The creepage distance between point a1 and point a2 is defined as B (mm) if the distance from point a1 to point a2 is shortest, along the surface of the spacer and across the short side of the spacer.

[21] A battery pack comprising a plurality of cells and a group of spacers as described in any of

[18] to

[20] .

[0007] Another embodiment of the present invention includes the following configuration: [A1] A spacer group comprising a plurality of spacers in the form of a sheet and having a rectangular shape when viewed from the thickness direction, wherein each spacer consists of an inner material having a rectangular planar shape and an outer material having a rectangular planar shape in which the inner material is contained in a sealed state, and the tolerance of the distance between the intersection of the diagonals of the spacer and the intersection of the diagonals of the inner material in a planar view of the spacer from the thickness direction is 0.010 to 10 mm. [A2] A battery pack comprising a plurality of single cells and the spacer group described in [A1]. [A3] A method for manufacturing a spacer included in the spacer group described in [A1], comprising: 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. [A4] The manufacturing method according to [A3], wherein the inner material supply step includes causing the inner material to absorb water. [A5] The manufacturing method according to [A3] or [A4], wherein the encapsulating material supply step includes supplying a strip-shaped encapsulating material and cutting the encapsulating material perpendicular to the flow direction. [A6] The manufacturing method according to any one of [A3] to [A5], wherein the sealing step includes sealing a pair of outer materials. [A7] The manufacturing method according to any one of [A3] to [A6], wherein the sealing step includes degassing the air contained between the pair of outer materials and sealing the outer edges of the pair of outer materials. [A8] The manufacturing method according to any one of [A3] to [A7], wherein the sealing step includes degassing the air contained between the pair of outer materials and sealing the outer edges of the pair of outer materials by reducing the pressure in a sealed space in which the laminate exists or by pushing the laminate from the center outward. [A9] The manufacturing method according to any one of [A3] to [A8], further comprising a cutting step of cutting the seal into a rectangle after the sealing step. [A10] The manufacturing method according to any one of [A3] to [A9], further comprising a cutting step of cutting the sealing body into a rectangle after the sealing step, wherein the dimensional error of the cut rectangle is greater than 2.0 mm and less than or equal to 5.0 mm.[A11] The manufacturing method according to any one of [A3] to [A10], further comprising a cutting step of cutting the sealing body into a rectangle after the sealing step, wherein the dimensional error of the cut rectangle is greater than 1.0 mm and less than or equal to 2.0 mm. [A12] The manufacturing method according to any one of [A3] to [A11], further comprising a cutting step of cutting the sealing body into a rectangle after the sealing step, wherein the dimensional error of the cut rectangle is less than or equal to 1.0 mm. [A13] The manufacturing method according to any one of [A3] to [A12], further comprising a cutting step of cutting the sealing body into a rectangle after the sealing step, wherein the position at which the sealing body is cut is adjusted based on a mark printed on the exterior material.

[0008] Another embodiment of the present invention includes the following configuration: [B1] A group of spacers comprising a plurality of sheet-like spacers having a rectangular shape when viewed from the thickness direction, wherein the tolerance of the creepage distance B of the plurality of spacers is 0.010 to 2.0 mm. (Creepage distance B) The creepage distance B is defined by the following methods (2-1) and (2-2), and its tolerance is calculated from any 10 spacers. (2-1) A first cell is placed on the first planar side of the spacer, and a second cell is placed on the second planar side of the spacer, with their planes parallel to each other, and a pressure of 0.1 MPa is applied from the thickness direction by the first cell and the second cell to sandwich the spacer and bring it into surface contact with the first cell and the second cell. (2-2) Let point a1 be a point on the edge of the contact portion between the first cell and the spacer, and let point a2 be a point on the edge of the contact portion between the second cell and the spacer, and let B (mm) be the creepage distance between point a1 and point a2 such that the shortest distance from point a1 to point a2 is reached along the surface of the spacer and across the short side of the spacer. [B2] A battery pack comprising a plurality of cells and the spacer group described in [B1]. [B3] A method for manufacturing a spacer included in the spacer group described in [B1], comprising: a encapsulating material supply step of supplying encapsulating material; an outer material supply step of supplying outer material; and a sealing step of forming a laminate by sandwiching both sides of the encapsulating material with the outer material, and sealing the outer materials around the encapsulating material to form a sealed body. [B4] The manufacturing method according to [B3], wherein the encapsulating material supply step includes causing the encapsulating material to absorb water. [B5] The manufacturing method according to [B3] or [B4], wherein the packaging material supply step includes supplying a strip-shaped packaging material and cutting the packaging material perpendicular to the flow direction. [B6] The manufacturing method according to any one of [B3] to [B5], wherein the sealing step includes sealing the outer edges of a pair of exterior materials. [B7] The manufacturing method according to any one of [B3] to [B6], wherein the sealing step includes degassing the air contained between a pair of exterior materials and sealing the outer edges of a pair of exterior materials.[B8] The manufacturing method according to any one of [B3] to [B7], 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. [B9] The manufacturing method according to any one of [B3] to [B8], further comprising a cutting step of cutting the seal into a rectangle after the sealing step. [B10] The manufacturing method according to any one of [B3] to [B9], further comprising a cutting step of cutting the seal into a rectangle after the sealing step, wherein the dimensional error of the cut rectangle is greater than 2.0 mm and less than or equal to 5.0 mm. [B11] The manufacturing method according to any one of [B3] to [B10], further comprising a cutting step of cutting the seal into a rectangle after the sealing step, wherein the dimensional error of the cut rectangle is greater than 1.0 mm and less than or equal to 2.0 mm. [B12] The manufacturing method according to any one of [B3] to [B11], further comprising a cutting step of cutting the sealing body into a rectangle after the sealing step, wherein the dimensional error of the cut rectangle is 1.0 mm or less. [B13] The manufacturing method according to any one of [B3] to [B12], further comprising a cutting step of cutting the sealing body into a rectangle after the sealing step, wherein the position at which the sealing body is cut is adjusted based on a mark printed on the outer material.

[0009] According to the present invention, a method for manufacturing a spacer that can stably obtain excellent thermal insulation performance, a group of spacers that can stably obtain excellent thermal insulation performance, and a battery pack using the group of spacers are provided.

[0010] This is a schematic cross-sectional view showing an example of a spacer manufactured by the manufacturing method according to the embodiment. This is a schematic diagram illustrating the internal material supply process in the manufacturing method of a spacer according to an example embodiment. This is a schematic diagram illustrating the external material supply process and the sealing process in the manufacturing method of a spacer according to an example embodiment. This is a schematic diagram illustrating the cutting process and the inspection process in the manufacturing method of a spacer according to an example embodiment. This is a schematic diagram illustrating the degassing process in the sealing process of the manufacturing method of a spacer according to an example embodiment. This is a schematic cross-sectional view showing a battery pack according to an example embodiment. This is a schematic diagram illustrating the creepage distance A of the spacer. This is a schematic diagram illustrating the creepage distance A of the spacer. This is a schematic diagram illustrating the creepage distance A of the spacer. This is a diagram illustrating the distance between the intersection of the diagonals of the spacer and the intersection of the diagonals of the internal material in a plan view of the spacer from the thickness direction. This is a schematic diagram showing an example of a spacer manufactured by the manufacturing method according to the embodiment. This is a schematic diagram illustrating the cutting process in the manufacturing method of a spacer according to an example embodiment. This is a schematic diagram illustrating the creepage distance B of the spacer. This is a schematic diagram illustrating the creepage distance B of the spacer.

[0011] Several embodiments of the present invention will be described below with reference to the drawings as appropriate. The dimensional ratios in the drawings are for illustrative purposes only and may differ from those in reality. In addition, identical components in the drawings are indicated by the same reference numerals, and descriptions of redundant components may be omitted.

[0012] [Method for Manufacturing Spacers] The method for manufacturing spacers according to this embodiment is a method for manufacturing spacers that are provided between each individual cell constituting a battery pack. This spacer is a component that prevents each individual cell from coming into contact with one another.

[0013] The method for manufacturing a spacer according to this embodiment includes the following inner material supply step, outer material supply step, and sealing step. Inner material supply step: Inner material is supplied. Outer material supply step: Outer material is supplied. Sealing step: A laminate is formed by sandwiching both sides of the inner material with the outer material, and the outer materials around the inner material are sealed together to form a sealed body. In the method for manufacturing a spacer according to one example of the embodiment, it is preferable that the inner material supply step includes allowing the inner material to absorb a liquid.

[0014] The method for manufacturing a spacer according to the embodiment preferably includes the following cutting step after the sealing step, and more preferably includes the following inspection step: Cutting step: Cutting the sealing body into a rectangle. Inspection step: Inspecting the appearance of the sealing body.

[0015] <Spacer> Figure 1 is a schematic cross-sectional view showing an example of a spacer manufactured by the manufacturing method according to the embodiment. Figure 12 is a schematic diagram showing an example of a spacer manufactured by the manufacturing method according to the embodiment viewed from the front. The example spacer 20 shown in Figures 1 and 12 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 and the inner material 22 having a rectangular planar shape and the inner material 22 having a rectangular planar shape and the outer edges 26 of the outer materials 24.

[0016] Insulating material can be used as the inner lining of the spacer. Typically, insulating paper is used as the insulating material, but it is not limited to this. The insulating material may include cotton sheets, polyimide fibers, aramid fibers, polytetrafluoroethylene (PTFE) fibers, glass fibers, rock wool, ceramic fibers, etc. The insulating material may also include particles such as silica particles, alumina particles, calcium silicate, clay minerals, vermiculite, mica, cement, perlite, fumed silica, aerogel, etc.

[0017] The thermal conductivity of the heat insulating 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 heat insulating 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 specimen (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 obtained from the phase difference (time difference) that occurs when the temperature fluctuation propagates from the upper surface to the intermediate surface of the test specimen, and the thermal conductivity is calculated from the product of the specific heat and the density.

[0018] 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 at or above 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 1.10 g / cm ３ or less, more preferably 1.00 g / cm ３ or less, and even more preferably 0.90 g / cm ３ or less. If the density of the heat insulating material is at or below 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 and upper limits 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.

[0019] Since the effect of suppressing thermal runaway of the assembled battery is higher, the inner package 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, etc., 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 package material can volatilize, absorbing the heat of vaporization from the surroundings and suppressing the temperature rise.

[0020] The liquid held in the insulating material is preferably a liquid with a boiling point of 80 to 250°C at atmospheric pressure, and more preferably a liquid with a boiling point of 100 to 150°C at atmospheric pressure. 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 also contain additives such as substances that impart antifreeze properties (antifreeze), preservatives, and pH adjusters.

[0021] Any material that can seal the inner material can be used as the outer packaging material; for example, resin sheets or metal sheets can be used. A laminate consisting of a metal foil layer and a resin layer is preferred as the outer packaging material because it easily provides excellent heat resistance and strength. For example, a laminate of three or more layers including a resin layer, a metal foil layer, and a sealant layer can be used.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] One possible configuration for housing the inner material within the outer material is, for example, 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.

[0026] 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.

[0027] When spacers are placed between individual cells, the ratio of the area of ​​the spacer to the area of ​​the individual cell, as viewed from the stacking direction, is preferably 0.8 or more, more preferably 0.9 or more, and even more preferably 0.95 or more. If the area ratio of the spacer to the individual cell is above the lower limit, short circuits due to contact between individual cells are less likely to occur, the pressure on the surface of the individual cells becomes more uniform, and performance degradation over time tends to be less likely. The area ratio of the spacer to the individual cell is preferably 1.2 or less, more preferably 1.1 or less, and even more preferably 1.05 or less. If the area ratio of the spacer to the individual cell 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 of the area ratio of the spacer to the individual cell 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.

[0028] <Manufacturing Equipment> The manufacturing equipment used in the manufacturing method according to one example of the embodiment will be described below. Figure 2 is a schematic diagram showing an inner packaging material supply device 110 used in the inner packaging material supply process. Figure 3 is a schematic diagram showing an outer packaging material supply device 120 used in the outer packaging material supply process and a sealing device 130 used in the sealing process. Figure 4 is a schematic diagram showing a cutting device 140 used in the cutting process and an inspection device 150 used in the inspection process. The method for manufacturing a spacer according to one example of the embodiment uses a spacer manufacturing apparatus 100 equipped with an inner packaging material supply device 110, an outer packaging material supply device 120, a sealing device 130, a cutting device 140, and an inspection device 150.

[0029] 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.

[0030] 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 device capable of supplying liquid L to the strip-shaped insulating material 22A on the first conveyor 114, and examples include a device equipped with a syringe pump and a slit nozzle.

[0031] In the example shown in Figure 2, two encapsulating material supply means 111 and two liquid supply means 112 are alternately provided in the flow direction, so that two layers of strip-shaped insulating material 22A containing liquid L are laminated. Note that the number of encapsulating 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 position where the strip-shaped insulating material 22A is laminated, and to control the position of the side edge of the laminated strip-shaped insulating material 22A with the EPC. This makes it possible to reduce the tolerance of the intersection distance D described later.

[0032] 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 strip-shaped insulation material 22A containing liquid L all at once with the cutting means 113 while it is stacked, the individual insulation materials constituting the inner materials 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 cutter for the strip-shaped insulation material 22A.

[0033] 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. Transport by conveyor is less prone to displacement of the internal materials 22 compared to transport by robot arm, and the tolerance of the intersection distance D described later can be made smaller.

[0034] In one example shown in Figure 3, 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.

[0035] 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. Preferably, the sealing device 130 is equipped with a degassing means 131 for removing air present between a pair of strip-shaped outer material 24A in the laminate 25, as illustrated in Figure 5. Preferably, the sealing device 130 is equipped with a sealing means 134 for sealing the strip-shaped outer material 24A around the inner material 22 in the laminate 25 while degassing is performed by the degassing means 131.

[0036] 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 the 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 the pair of strip-shaped outer materials 24A of the laminate 25 along the width direction (end seal). The first sealing portion and the second sealing portion of the sealing means 134 are not particularly limited, and for example, a heat sealer can be used.

[0037] One example of a degassing means 131 shown in Figure 5 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.

[0038] 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. Moreover, by sealing while pressing the encapsulating material 22 of the laminate 25 with the sponge body 133, displacement of the encapsulating material 22 during sealing can be suppressed, thus making the tolerance of the intersection distance D described later smaller.

[0039] In the sealed body 28 after sealing by the sealing device 130, a plurality of inner packaging materials 22 are individually sealed at predetermined intervals in the flow direction. An example of the cutting device 140 shown in FIG. 4 is a device that typically cuts the seal portion around the inner packaging material 22 with respect to the sealed body 28 after sealing, typically in a rectangular shape, and punches out the spacer 20. The cutting device 140 may be any device that can punch out a plurality of spacers 20 from the sealed body 28, and examples include a Thomson type and a mold. Note that the cutting device 140 may cut the seal portion around the inner packaging material 22 in the sealed body 28 by a laser.

[0040] The cutting device 140 preferably has a mechanism for performing position adjustment using the alignment marks pre-printed on the strip-shaped outer packaging material 24A when punching out each spacer 20 from the sealed body 28. By providing such a position adjustment mechanism, the dimensional accuracy of the outer shape of the obtained spacer 20 is improved. Further, the cutting device 140 may be provided with means for performing ear hole processing on the outer edge portion around the inner packaging material 22 when punching out each spacer 20 from the sealed body 28.

[0041] The inspection device 150 is a device that inspects the outer shape and appearance of each spacer 20 obtained by cutting the sealed body 28, and separates defective products to a waste course and separates them from the products. Examples of the inspection device 150 include a device provided with light irradiation means for irradiating light from various angles to the surface of the portion where the inner packaging material 22 of the spacer 20 is accommodated, imaging means for imaging the surface of the portion where the inner packaging material 22 of the spacer 20 is accommodated, and determination means for analyzing the captured image and determining the presence or absence of wrinkles.

[0042] The position where the spacer 20 determined to be a defective product is flowed to the waste course is not particularly limited, and it may be flowed from the inspection device 150 to the waste course, or may be flowed to a waste course that branches on the downstream side of the inspection device 150.

[0043] <Manufacturing method> Hereinafter, as an example of the manufacturing method of the spacer according to the embodiment, a method using the above-described spacer manufacturing apparatus 100 will be described.

[0044] (Insulation Material Supply Process) The insulation material supply process is a process of supplying the insulation material, and preferably includes supplying a long strip of insulation material, impregnating the strip of insulation material with a liquid, preferably water, laminating the strip of insulation material, and cutting the laminated strip of insulation material perpendicular to the flow direction to form single sheets of insulation material. The insulation material supply process may also include supplying the insulation material with one end fixed in position in a width perpendicular to its flow direction.

[0045] 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.

[0046] 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. Note that insulating materials other than the insulating paper described above for the spacer may be used as the strip-shaped insulating material 22A. The width of the strip-shaped insulating material 22A can be set appropriately according to the product size. By matching the width of the strip-shaped insulating material 22A to the width of the inner material 22 of the spacer 20, which is the product, and 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, and the tolerance of the intersection distance D described later can be made smaller. In one example, it is preferable to supply a strip-shaped insulating material 22A having a width of 50 to 90% of the width perpendicular to the flow direction of the strip-shaped exterior material 24A.

[0047] 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 amount of the encapsulating material, which is set to 100%. The higher the water absorption rate, the less likely the position of each encapsulating 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 described later 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 overflowing 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 more preferred.

[0048] 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. Note that, instead of water, a liquid other than water as described in the spacer above may be used as the liquid L.

[0049] 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.

[0050] It is preferable that the positional misalignment in the width direction between the stacked strip-shaped insulation materials 22A is 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 tolerances of the creepage distance B and intersection distance D, which will be described later.

[0051] 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 positional misalignment in the width direction between the stacked strip-shaped insulation material 22A to within 1 mm, and further reduces the tolerance of the intersection distance D described later.

[0052] 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 materials 22 are less likely to shift, and the tolerances of the creepage distance B and intersection distance D described later can be made smaller. It is preferable that the cutting by the cutting means 113 be performed so that the cut surface is as perpendicular as possible to the plane of the strip-shaped insulation material 22A. It is preferable that the length deviation of each inner material 22 in the flow direction is within 1 mm. This makes it possible to make the tolerance of the intersection distance D described later smaller.

[0053] 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.

[0054] (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.

[0055] As for the strip-shaped exterior material 24A, one method is to use an exterior material roll with a predetermined width as the raw material roll, and 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.

[0056] 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 at least one of registration marks for positioning in the sealing process and alignment marks for positioning in the cutting process pre-printed on it. By using these marks to position the materials in the sealing and cutting processes, the dimensional accuracy of the resulting spacer 20 can be improved, and the tolerances for creepage distance A, creepage distance B, and intersection distance D, described later, can be reduced.

[0057] (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 together to seal it.

[0058] 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 133 against it from above. At this time, by pushing the laminated body 25 from its center outwards, the air contained mainly in the inner material 22 between the pair of strip-shaped outer materials 24A 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.

[0059] 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 in which the laminate is located, or by pushing the laminate from the center outwards. Even when sealing is performed while reducing the pressure within the sealed space in which the laminate 25 is located, displacement of the inner material 22 sandwiched between the strip-shaped insulating material 24A during sealing is less likely to occur, so the tolerance of the intersection distance D described later can be made smaller.

[0060] More specifically, the degassing means 131 seals the laminated body 25, which has been transported onto the support stand 132, by sandwiching it between molds from above and below, and then depressurizes the sealed space using 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.

[0061] 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 inside of the mold is repressurized, and after a predetermined sealing time has elapsed, the upper and lower molds are separated. This forms a sealed body 28 in which the inside containing the inner material 22 is sufficiently degassed. It is preferable to seal the pair of strip-shaped outer materials 24A by heating, i.e., by heat sealing.

[0062] 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 inner 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 inner material 22 in the pair of strip-shaped outer materials 24A of the laminate 25 along the width direction (end seal). This forms a sealed body 28 in which the interior containing the inner material 22 is sufficiently degassed. In addition, by pressing the inner material 22 of the laminate 25 with the sponge body 133 while sealing, displacement of the inner material 22 during sealing can be suppressed, and the tolerance of the intersection distance D described later can be made smaller. It is preferable to seal the pair of strip-shaped outer materials 24A by heating, that is, by heat sealing.

[0063] By performing side seals and end seals in stages, it is possible to easily accommodate changes in the size of the target spacer 20.

[0064] 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, creepage distance B, and intersection distance D of the resulting spacer 20, as described later.

[0065] (Cutting process) For example, a cutting device 140 is used to cut the sealing portion around each inner material 22 in the sealed body 28 into a rectangle, thereby sequentially manufacturing a plurality of spacers 20. The dimensional error of the rectangle to be cut in the cutting process is preferably more than 2.0 mm and 5.0 mm or less, more preferably more than 1.5 mm and 2.0 mm or less, even more preferably more than 1.0 mm and 2.0 mm or less, especially preferably more than 1.0 mm and 1.5 mm or less, particularly preferably more than 0.5 mm and 1.0 mm or less, and most preferably 0.5 mm or less. Cutting with a guillotine cutter can make the dimensional error of the rectangle more than 1.0 mm and 1.5 mm or less, and cutting by punching can make it possible to cut with an accuracy of 0.5 mm or less. As a result, the tolerances of the creepage distance A, creepage distance B, and intersection distance D of the resulting spacers 20 can be made smaller.

[0066] 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 creepage distance A, creepage distance B, and intersection distance D, as described later. In addition, in 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 inner material 22.

[0067] (Inspection process) For example, the inspection device 150 inspects the appearance of the sealed body after cutting, that is, each spacer 20 punched out from the sealed body 28. Spacers 20 that are judged 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.

[0068] 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 inspection. The captured images are then evaluated using a set algorithm to determine the presence or absence of wrinkles and any misalignment of the internal material on the front and back surfaces of the portion of the spacer 20 containing the internal material 22, and defective products are sorted according to the results. Parameters used for sorting include, for example, measuring the presence or absence of wrinkles and misalignment based on the difference in brightness, i.e., the difference in contrast. It is also possible to detect the size of the wrinkles by the detected area. Regarding 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 based on the above-mentioned difference in density, and defective products are determined based on specified values. The sealed products determined to be good products are transported to the exit, and the sealed products determined to be defective products can be discarded 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 part of the spacer 20 in which the inner material 22 is contained, it can be determined to be an appearance defect.

[0069] Furthermore, the method for manufacturing a spacer according to the present invention is not limited to the method using the spacer manufacturing apparatus 100 shown in Figures 2 to 4. For example, the method for manufacturing a spacer according to one embodiment may be a method using a spacer manufacturing apparatus 100 equipped with an inner packaging material supply device 110, an outer packaging material supply device 120, a sealing device 130, and a cutting device 140, but without an inspection device 150, as shown in the example in Figure 13.

[0070] [Battery Pack] A battery pack according to one example of the embodiment comprises a plurality of single cells and a group of spacers. The group of spacers includes a plurality of sheet-like spacers that are rectangular in shape when viewed from the thickness direction. Each spacer constituting the group of spacers is placed between each single cell. Figure 6 is a schematic diagram showing a battery pack 1 of one example of the embodiment. The battery pack 1 comprises a housing 30, a plurality of single cells 10 housed in the housing 30, and a plurality of sheet-like spacers 20 placed between each single 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, the plurality of 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 upper surface of the bottom plate 30a of the housing 30 and each single cell 10, but the embodiment is not limited to this.

[0071] The spacer 20 is a component installed between each individual cell 10 that makes up the battery pack 1, preventing the individual cells 10 from coming into contact with each other. Even if the individual cells 10 that make up the battery pack 1 expand during use, the flexible spacer 20 absorbs the expansion pressure. 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 spread of damage to the surrounding individual cells 10 through a chain reaction is suppressed, thereby preventing thermal runaway of the battery pack 1.

[0072] For example, the spacer 20 shown in Figure 1 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.

[0073] 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.

[0074] <Spacer Group> Before placing multiple spacers between each cell, they can be bundled together and stored, transported, and sold as a spacer group. In the spacer group according to the embodiment, it is preferable that the tolerance of the creepage distance A, which is determined by the method described later, is 0.010 to 2.0 mm. If the tolerance of the creepage distance A is within the above range, it is easier to stably obtain excellent thermal insulation performance with the spacers. In the spacer group according to the embodiment, the tolerance of the creepage distance A of the multiple spacers is more preferably 0.010 to 1.0 mm, and even more preferably 0.010 to 0.50 mm.

[0075] (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) The first single cell is placed on the first planar side of the spacer, and the second single cell is placed on the second planar side of the spacer, with their planes parallel to each other. While maintaining the parallelism of their planes, the first and second single cells are brought closer to the spacer. (1-2) If the first single cell and the spacer are in point contact, the point at the contact point is defined as point a1. If the second single cell and the spacer are in point contact, the point at the contact point is defined as point a2. If the second single cell and the spacer are in point contact, the point at the contact point is defined as point a2. The creepage distance A (mm) is defined as the shortest distance from point a1 to point a2 along the spacer and across the short side of the spacer.

[0076] 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 contact each other. 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.

[0077] 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 7) is determined to be A (mm) if the distance to points a1 and a2 is shortest along the surface of the spacer 20 and across the short side of the spacer 20 is shortest. 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. The creepage distance A is similarly determined for any 10 spacers, and their tolerances are calculated.

[0078] An example shown in Figure 9 is one in which, in step (1-1), when the first cell 10A and the second cell 10B are brought close to the spacer 20, 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, 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.

[0079] In this example, in step (1-2), the point of contact 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) is determined as A (mm) if the distance to points a1 and a2 is shortest along the surface of the spacer 20 and across the short side of the spacer. Typically, point a2, which is the point with 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. The creepage distance A is similarly determined for any 10 spacers, and their tolerances are calculated.

[0080] 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 make point contact.

[0081] 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, the creepage distance A is calculated for any 10 spacers, and their tolerances are calculated.

[0082] The tolerance of creepage distance A tends to increase in step (1-1) if at least one of the contact 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.

[0083] The multiple spacers included in the spacer group preferably have a creepage distance B tolerance of 0.010 to 2.0 mm, which is determined by the method described later. If the creepage distance B tolerance is within the above range, excellent thermal insulation performance can be reliably obtained by the spacers. The creepage distance B tolerance of the multiple spacers is more preferably 0.010 to 1.0 mm, and even more preferably 0.010 to 0.50 mm.

[0084] (Tolerance of creepage distance B) Creepage distance B is defined by the following methods (2-1) and (2-2), and its tolerance is calculated from any 10 spacers. (2-1) The first cell is placed on the first planar side of the spacer, and the second cell is placed on the second planar side of the spacer, with their planes parallel to each other. A pressure of 0.1 MPa is applied from the thickness direction by the first and second cells to sandwich the spacer and make surface contact with the first and second cells. (2-2) Point a1 is the point on the edge of the contact portion between the first cell and the spacer, and point a2 is the point on the edge of the contact portion between the second cell and the spacer. The creepage distance between point a1 and point a2 is defined as B (mm) if the distance from point a1 to point a2 is shortest, along the surface of the spacer and across the short side of the spacer.

[0085] In step (2-1) of determining the creepage distance B, the first cell is in contact with the first plane of the spacer, and the second cell is in contact with the second plane of the spacer, and a pressure of 0.1 MPa is applied from the thickness direction by the first and second cells. In step (2-1), because pressure is applied from the thickness direction toward the spacer by the first and second cells, even if there are some irregularities such as wrinkles on the first and second planes of the spacer, these irregularities tend to be flattened, making surface contact easier.

[0086] For example, as shown in Figure 14, in step (2-1), 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, with their planes parallel to each other. The spacer 20 is sandwiched between the first cell 10A and the second cell 10B by applying a pressure of 0.1 MPa from the thickness direction, so that the first cell 10A and the second cell 10B are in surface contact with both sides of the spacer 20.

[0087] In this example, in step (2-2), as shown in Figure 15, point a1 is defined as the point on the edge of the contact portion between the first cell 10A and the spacer 20, and point a2 is defined as the point on the edge of the contact portion between the second cell 10B and the spacer 20. Then, the creepage distance B (mm) is determined between point a1 and point a2, which is the shortest distance from point a1 to point a2 along the surface of the spacer 20 and across the short side of the spacer. Typically, points a1 and a2, which are the shortest distances from point a1 to point a2 along the surface of the spacer 20 and across the short side of the spacer, 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. The creepage distance B is similarly determined for any 10 spacers, and their tolerances are calculated.

[0088] (Tolerance for Intersection Distance) In the spacer group according to this embodiment, it is preferable that the tolerance for the distance between the intersection of the diagonals of the spacer and the intersection of the diagonals of the inner 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 for convenience showing the case where the position of the inner material 22 in the spacer 20 is shifted. When the intersection of the diagonals of the spacer 20, which has a rectangular plan shape, i.e., the diagonals of the outer material 24, which has a rectangular plan shape, is point a, and the intersection of the diagonals of the inner material 22, which has a rectangular plan shape, is point b, the intersection distance D is the distance between point a and point b. The tolerance for intersection distance D is calculated from any 10 spacers.

[0089] If the tolerance of the intersection distance D is within the above range, excellent thermal insulation performance can be stably obtained by the spacers. The tolerance of the intersection distance D of the multiple spacers in the spacer group according to the embodiment is preferably 0.010 to 5.0 mm, and more preferably 0.010 to 2.5 mm.

[0090] <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.

[0091] 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.

[0092] It should be noted that the present invention is not limited to the embodiments described above. For example, instead of using strip-shaped insulation material and strip-shaped exterior material, a spacer may be manufactured by using a single sheet of insulation material and a single sheet of exterior material and performing the inner 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 from the sealed body after the sealing process. Furthermore, it is possible to replace the components in the above embodiments with well-known components as appropriate, without departing from the spirit of the present invention, and the above-described modifications may be combined as appropriate.

[0093] 1. Battery pack 10. Single cell 10A. First single cell 10B. Second single cell 20. Spacer 20a. First plane 20b. Second plane 22. Inner material 22A. Strip-shaped insulating material 24. Outer material 26. Outer edge 30. Housing 100. Spacer manufacturing device 110. Inner material supply device 111. Inner material supply means 112. Liquid supply means 120. Outer packaging material supply device 121. First outer material supply means 122. Second outer material supply means 130. Sealing device 131. Degassing means 140. Cutting device 150. Inspection device

Claims

1. A method for manufacturing a spacer comprising an inner encapsulant and an outer casing, comprising: an inner encapsulant supply step of supplying an inner encapsulant; an outer casing supply step of supplying an outer casing; and a sealing step of forming a laminate by sandwiching both sides of the inner encapsulant with the outer casing, and sealing the outer casing around the inner encapsulant to form a sealed body, wherein the inner encapsulant supply step includes causing the inner encapsulant 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 is present, 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 rectangular shape after the sealing step.

7. The manufacturing method according to claim 1, further comprising a cutting step of cutting the sealing body into a rectangle after the sealing step, wherein the dimensional error of the cut rectangle is greater than 2.0 mm and less than or equal to 5.0 mm.

8. The manufacturing method according to claim 1, further comprising a cutting step of cutting the sealing body into a rectangle after the sealing step, wherein the dimensional error of the cut rectangle is greater than 1.0 mm and less than or equal to 2.0 mm.

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

10. The manufacturing method according to claim 1, further comprising a cutting step of cutting the seal into a rectangle after the sealing step, wherein the position at which the seal is cut is adjusted based on marks 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 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, wherein the manufacturing method is further comprising determining whether the product is good or defective based on the results of the inspection.

13. The manufacturing method according to claim 1, further comprising a cutting step of cutting the seal into a rectangle after the sealing step, and an inspection step of inspecting the appearance of the surface of the seal, wherein seals determined to be good products are transported to an exit, and seals determined to be defective products are not transported to an exit but discarded.

14. The manufacturing method according to claim 1, wherein the inner material supply step includes supplying the inner 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 a plurality of sheet-like spacers with a rectangular shape when viewed from the thickness direction, wherein each spacer consists of an inner material with a rectangular planar shape and an outer material with a rectangular planar shape in which the inner material is contained in a sealed state, and the tolerance of the distance between the intersection of the diagonals of the spacer and the intersection of the diagonals of the inner material in a planar view of the spacer from the thickness direction is 0.010 to 10 mm.

19. A battery pack comprising a plurality of single cells and the spacer group described in claim 18.

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