Method for manufacturing bipolar battery

Abstract

The invention provides a method for manufacturing a bipolar battery, which can fill a foaming agent in a gap between battery modules through a simple method. This bipolar battery manufacturing method is provided with: a lamination step for manufacturing a laminate by alternately laminating a battery module and a cooler; an attaching step in which a sheet containing a polyol is attached to at least one of the surfaces exposed from the cooler and facing each other, among the battery modules adjacent to each other in the stacking direction, said battery modules being located at a position higher than the liquid level of the foaming agent that is subsequently filled with the battery modules before foaming; an insertion step of inserting the laminate into the interior of the battery case; and a foaming step of filling the battery case with a foaming agent until the battery case reaches the liquid level and foaming the battery case. The foaming agent is a two-liquid curable foamed polyurethane containing a polyol and an isocyanate, and the content of the isocyanate is higher than the content of the polyol.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a bipolar battery. Background Technology

[0002] Conventionally, the technology described in Patent Document 1 is an example of such a technical field. In the method for manufacturing a bipolar battery described in Patent Document 1, multiple battery modules are stacked with an electrolyte layer between them, each having a positive electrode on one side of a current collector and a negative electrode on the other side. The space between adjacent current collectors in the stacking direction is filled with a filler material to surround the positive and negative electrodes.

[0003] Patent Document 1: Japanese Patent No. 5315653 Summary of the Invention

[0004] Thus, in bipolar batteries with multiple stacked battery modules, to achieve cooling of the battery modules, coolers are mostly placed between adjacent battery modules, i.e., battery modules and coolers are stacked alternately, and the coolers absorb the heat from the battery modules. Moreover, in order to constrain the stacked battery modules and coolers within the battery casing, a measure is taken to fill the gaps between the battery modules and coolers and the battery casing with a foaming agent after the stacked battery modules and coolers are inserted into the battery casing.

[0005] However, due to the different sizes of battery modules and coolers, if battery modules and coolers are stacked alternately, gaps will be generated between adjacent battery modules in the stacking direction. Furthermore, since these gaps extend in a direction orthogonal to the stacking direction, the foaming agent alone cannot easily penetrate these gaps through natural foaming. To solve this problem, a method of vacuuming (i.e., depressurization-based filling) after filling the battery casing with the foaming agent has been studied, but this introduces problems such as the need for large equipment including a depressurization device.

[0006] This invention was made to solve this technical problem, and its purpose is to provide a method for manufacturing a bipolar battery, which can fill the gaps between battery modules with a foaming agent through a simple method.

[0007] The method for manufacturing a bipolar battery according to the present invention is characterized by comprising: a lamination step, wherein multiple battery modules and multiple coolers are alternately laminated to form a laminate; an attachment step, wherein a sheet containing a polyol is attached to at least one of the surfaces of adjacent battery modules in the lamination direction that are located at a position higher than the liquid level of the subsequently filled foaming agent before foaming; an insertion step, wherein the laminate with the attached polyol-containing sheet is inserted into the interior of a pre-fabricated battery casing; and a foaming step, wherein the foaming agent is filled into the battery casing until the liquid level is reached and foamed, wherein the foaming agent is a two-component curable foamed polyurethane containing a polyol and an isocyanate, wherein the isocyanate content is higher than the polyol content.

[0008] The method for manufacturing a bipolar battery according to the present invention includes: an attachment step, in which a sheet containing a polyol is attached to at least one of the surfaces of adjacent battery modules in the stacking direction that are located at a position higher than the liquid level before foaming of the subsequently filled foaming agent; an insertion step, in which the laminate with the attached polyol-containing sheet is inserted into the interior of a pre-fabricated battery casing; and a foaming step, in which a foaming agent is filled into the battery casing until the liquid level is reached and foamed, wherein the foaming agent is a two-component curable foamed polyurethane containing a polyol and an isocyanate, and the isocyanate content is higher than the polyol content. That is, by using a foaming agent with an excess of isocyanate in the mixing ratio, unreacted isocyanate in the foaming agent can react with the polyol in the polyol-containing sheet, thereby promoting foaming in the gaps between adjacent battery modules in the stacking direction. Therefore, the foaming agent can easily enter the gaps between the battery modules. Furthermore, compared to filling methods based on pressure reduction, this method eliminates the need for large equipment such as pressure reduction devices, thus simplifying the manufacturing process. Consequently, it is also possible to fill the gaps between battery modules using a simple method.

[0009] Invention Effects

[0010] According to the present invention, a foaming agent can also be filled in the gaps between battery modules by a simple method. Attached Figure Description

[0011] Figure 1 This is a flowchart illustrating a method for manufacturing a bipolar battery according to an embodiment.

[0012] Figure 2 It is a schematic cross-sectional view used to illustrate the foaming step (the state before foaming).

[0013] Figure 3It is a schematic cross-sectional view used to illustrate the foaming step (the state during the foaming process).

[0014] Figure 4 It is a schematic cross-sectional view used to illustrate the foaming process (the state after foaming). Detailed Implementation

[0015] Hereinafter, embodiments of the manufacturing method of the bipolar battery according to the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are labeled with the same symbols, and repeated descriptions are omitted. Furthermore, in Figures 2-4 The image depicts only a portion of the cross-section of the bipolar battery (e.g., the right half). Furthermore, the following example illustrates a battery module and cooler stacked along a vertical direction, i.e., an example where the stacking direction is vertical.

[0016] Figure 1 This is a flowchart illustrating a method for manufacturing a bipolar battery according to the embodiments described. For example... Figure 1 As shown, the manufacturing method of the bipolar battery involved in this embodiment includes a stacking step S11, an attachment step S12, an insertion step S13, and a foaming step S14.

[0017] In the stacking step S11, a stacked body 10 is fabricated by alternately stacking multiple battery modules 11 and multiple coolers 12. The battery module 11 is, for example, a flat plate with multiple battery cells stacked on it. Although not shown, each battery cell has bipolar electrodes, and a current collector and a separator coated with positive and negative electrode active materials are alternately stacked on both sides. Furthermore, each battery cell is configured to directly conduct electricity in the stacking direction of the bipolar electrodes. In the battery module 11, the stacking direction of the battery cells is the same as the direction in which the current flows. In this embodiment, the stacking direction of the battery cells is the same as the stacking direction of the battery module 11 and the cooler 12.

[0018] The cooler 12 is a flat box shape with a space for refrigerant to circulate inside, and the refrigerant flowing through it absorbs heat from the battery module 11, thereby cooling the battery module 11. Figure 2 As shown, the cooler 12 is disposed between a pair of adjacent upper and lower battery modules 11 in the stacking direction and is configured to absorb heat from the pair of upper and lower battery modules 11. That is, the cooler 12 is sandwiched between the bottom surface 11b of the upper battery module 11 and the top surface 11a of the lower battery module 11 in the pair of upper and lower battery modules 11.

[0019] Although not shown, the cooler 12 includes, for example, a first metal plate bonded to the bottom surface 11b of the upper battery module 11; a second metal plate bonded to the top surface 11a of the lower battery module 11; and a metal corrugated plate disposed between the first metal plate and the second metal plate to form a refrigerant flow path.

[0020] Therefore, in the lamination step S11, a laminate 10 is fabricated by alternately stacking multiple pre-fabricated battery modules 11 and multiple coolers 12 in the vertical direction. At this time, a conductive adhesive is applied between the battery modules 11 and the coolers 12, and the battery modules 11 and the coolers 12 are fixed together by the conductive adhesive.

[0021] like Figure 2 As shown, for example, in the case where four battery modules 11 and three coolers 12 are alternately stacked in a laminate 10, three gaps S are created by adjacent battery modules 11 and the coolers 12 disposed between them. More specifically, the gaps S are formed by the bottom surface 11b between the upper battery modules 11, the top surface 11a of the lower battery module 11, and the side surface 12a of the cooler 12 disposed between the upper and lower battery modules 11. The gaps S extend in a direction orthogonal to the vertical direction (stack direction) (e.g., the horizontal direction).

[0022] Furthermore, when the laminate 10 is inserted into the interior of the battery housing 20, the three gaps S are respectively connected to the interior of the battery housing 20.

[0023] In the attachment step S12 following the lamination step S11, a sheet 13 containing polyol is attached to at least one of the surfaces of adjacent battery modules 11 in the vertical direction that are located at a position higher than the liquid level 14a of the subsequently filled foaming agent 14 before foaming.

[0024] Specifically, for example Figure 2 As shown, when the laminate 10 is subsequently inserted into the battery housing 20 and a foaming agent 14 is filled into the battery housing 20, relative to the liquid surface 14a before foaming of the filled foaming agent 14, among the three gaps S, the lowest gap S is lower than the liquid surface 14a, and the remaining two gaps S are higher than the liquid surface 14a. That is, the lowest gap S is filled with foaming agent 14, while the remaining two gaps S are not filled with foaming agent 14.

[0025] In this condition, a sheet 13 containing polyol is attached to at least one of the surfaces of each adjacent battery module 11 that are exposed from the cooler 12 and face each other, namely, at least one of the bottom surface 11b of the upper battery module 11 exposed from the cooler 12 and facing each other.

[0026] In this embodiment, a sheet 13 containing polyol is attached only to the top surface 11a of the lower battery module 11 that forms the gap S (see reference). Figure 2 However, the polyol-containing sheet 13 may be attached only to the bottom surface 11b of the upper battery module 11 that forms the gap S, or to both the bottom surface 11b of the upper battery module 11 and the top surface 11a of the lower battery module 11. Furthermore, the liquid level 14a of the foaming agent 14 is determined by the amount of foaming agent 14 filled and the volume of the battery casing 20.

[0027] Furthermore, the attachment range of the sheet 13 containing polyols can, for example, cover the entire area of ​​the bottom surface 11b of the upper battery module 11 and / or the top surface 11a of the lower battery module 11 that forms the gap S, or it can be a part of it.

[0028] The sheet 13 containing polyols is, for example, a sheet permeated with polyols or a sheet impregnated with polyols. Examples of polyols contained in the sheet 13 include acrylic polyols, polyester polyols, epoxy polyols, and alkyd polyols.

[0029] In the insertion step S13 following the attachment step S12, the laminate 10 with the polyol-containing sheet 13 attached is inserted into the interior of the pre-fabricated battery casing 20. For example... Figure 2 As shown, the battery casing 20 has, for example, a box-shaped casing body 21 with an opening at the top and a cover 22 for blocking the opening of the casing body 21. Moreover, the cover 22 and the casing body 21 are fastened together by bolts with their respective flanges 221 and 211 overlapping.

[0030] Therefore, in the insertion step S13, after the laminate 10 with the sheet 13 containing polyol attached is placed inside the housing body 21, the cover 22 is fastened to the housing body 21.

[0031] In the foaming step S14 following the insertion step S13, a foaming agent 14 is filled into the battery casing 20 and foamed. Specifically, as... Figure 2As shown, for example, the foaming agent 14 is filled into the interior of the battery housing 20 through a filling port formed in the battery housing 20 until the liquid surface 14a is reached. The foaming agent 14 is a two-component curable foamed polyurethane containing a polyol (main agent) and an isocyanate (curing agent). In this foaming agent 14, the content of isocyanate is higher than the content of polyol.

[0032] Examples of polyols include acrylic polyols, polyester polyols, epoxy polyols, and alkyd polyols. Examples of isocyanates include aliphatic or aromatic isocyanates with two or more functional groups, such as hexamethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate, xylene diisocyanate, 4,4-diphenylmethane diisocyanate, and lysine diisocyanate.

[0033] At this point, the polyol and isocyanate are mixed in a mixing ratio with an excess of isocyanate, and then filled into the interior of the battery casing 20. Furthermore, the amount of foaming agent 14 added is determined based on the filling volume and foaming ratio. For example, if the foaming ratio is 2, then half the filling volume is filled.

[0034] If polyol and isocyanate are mixed, a foaming reaction occurs, and foaming agent 14 expands and increases in size. Therefore, as... Figure 3 As indicated by the arrows, while the foaming agent 14 expands in the vertical direction, it also reaches the entrance of the gap S between adjacent battery modules 11 (i.e., the part where the gap S communicates with the interior of the battery casing 20). As described above, in natural foaming, even if the foaming agent 14 reaches the entrance of the gap S between adjacent battery modules 11, in order to enter the interior of the gap S, the foaming force of the foaming agent 14 is mainly concentrated in the vertical direction. Therefore, the force in the direction orthogonal to the vertical direction (e.g., the horizontal direction) is weak, and it is difficult for the foaming agent 14 to enter the interior of the gap S.

[0035] In this embodiment, since a sheet 13 containing polyol is pre-attached to the top surface 11a of the lower battery module 11 forming the gap S, the unreacted isocyanate in the foaming agent 14 reacts with the polyol in the sheet 13 containing polyol, thereby promoting foaming in the gap S (see reference). Figure 3 (Enlarged view). That is, the sheet 13 containing polyols plays a role in attracting the foaming agent 14 into the interior of the gap S. As a result, the foaming agent 14 can easily enter the gap S between the battery modules.

[0036] The result, such as Figure 4 As shown, the foaming agent 14 not only fills the gaps in the vertical direction (the gap between the battery housing 20 and the laminate 10), but also fills the gaps S between adjacent battery modules 11 in the vertical direction.

[0037] In addition, the foaming agent 14 is in a liquid state before foaming, but changes from a liquid state to an emulsion state through the foaming reaction, then to a gel state, and finally to a solid state (cured).

[0038] The manufacturing method of the bipolar battery according to this embodiment includes: an attachment step S12, in which a sheet 13 containing polyol is attached to at least one of the surfaces of adjacent battery modules 11 located at a position higher than the liquid surface 14a of the subsequently filled foaming agent 14 before foaming; an insertion step S13, in which a laminate 10 containing the sheet 13 of polyol is attached to the interior of a battery housing 20; and a foaming step S14, in which the foaming agent 14 is filled into the battery housing 20 until the liquid surface 14a is reached and foamed, wherein the foaming agent 14 is a two-component curable foamed polyurethane containing polyol and isocyanate, and the content of isocyanate is higher than the content of polyol.

[0039] That is, in the manufacturing method of this embodiment, by using a foaming agent 14 with an excess of isocyanate, the unreacted isocyanate in the foaming agent 14 can react with the polyol in the sheet 13 containing polyol, thereby promoting foaming in the gap S between adjacent battery modules 11 in the vertical direction. Therefore, the foaming agent can easily enter this gap S. Furthermore, compared to the case of filling based on depressurization, the introduction of large equipment such as a depressurization device is not required, thus simplifying the manufacturing method. As a result, the foaming agent 14 can be filled into the gap S between the battery modules 11 using a simple method.

[0040] Furthermore, in this embodiment, foaming agent 14 is described as an example of foamed polyurethane, but foamed epoxy resin or foamed silicone resin may also be used instead of foamed polyurethane. In this case, a sheet that promotes the foaming of foamed epoxy resin or foamed silicone resin is used instead of sheet 13 containing polyol.

[0041] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the above embodiments. Various design changes can be made without departing from the spirit of the present invention as set forth in the claims.

[0042] Symbol Explanation

[0043] 10-Laminated body, 11-Battery module, 11a-Top surface, 11b-Bottom surface, 12-Cooler, 12a-Side surface, 13-Sheet containing polyol, 14-Blowing agent, 14a-Liquid surface, 20-Battery housing, 21-Housing body, 22-Cover, 211, 221-Flanges, S-Gap.

Claims

1. A method of manufacturing a bipolar battery, characterized by, Comprising: a stacking step of alternately stacking a plurality of battery modules and a plurality of coolers to make a stacked body; a sticking step of sticking a sheet containing a polyol to at least one of surfaces exposed from the coolers and facing each other in each of the battery modules each other, which are located higher than a liquid level of a foaming agent to be filled subsequently, in each of the battery modules adjacent to each other in a stacking direction; a inserting step of inserting the stacked body to which the sheet containing the polyol is stuck, into an inside of a battery case made in advance; and a foaming step of filling the foaming agent into the battery case until the liquid level is reached and foaming it, the foaming agent is a two-liquid curing type foaming polyurethane containing a polyol and an isocyanate, and a content rate of the isocyanate is higher than a content rate of the polyol.

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