JP6997950B2 - Manufacturing method of laminated battery module - Google Patents

Description

The present invention relates to a method for manufacturing a laminated battery module in which a plurality of laminated battery cells are arranged in a predetermined direction and electrically connected to each other.

As one form of a battery, a laminated battery cell in which an electrode body is housed in a laminated film outer body is known (see Patent Document 1). A laminated battery module in which a plurality of laminated battery cells are arranged and electrically connected is widely used as a high-output power source for mounting on a vehicle.

Generally, the laminating film exterior has a smooth surface and low friction. Therefore, when manufacturing a laminated battery module by combining laminated battery cells, the positions of the laminated battery cells tend to shift from each other, which makes assembly difficult. In other words, the laminated battery module has poor assembleability. In order to improve the assemblability, for example, it is conceivable to fix the adjacent laminated battery cells so as not to shift each other. In relation to this, for example, Patent Document 1 states that, although it is not a technique relating to the manufacture of a module, the assembleability of a laminated battery can be improved by fixing the electrode body to the laminated film outer body with an adhesive tape. Is described.

Japanese Unexamined Patent Publication No. 2016-170966

However, when a fixing member such as an adhesive tape is used as described above, the weight and volume of the module are increased by that amount. Therefore, in manufacturing a laminated battery module, a new technique for improving assemblability while avoiding an increase in weight and volume has been required.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a method for manufacturing a laminated battery module capable of improving assemblability while avoiding an increase in weight and volume.

INDUSTRIAL APPLICABILITY According to the present invention, there is provided a method for manufacturing a laminated battery module in which a first laminated battery cell and a second laminated battery cell are arranged side by side and electrically connected to each other. In such a manufacturing method, the portion of the first laminated battery cell in contact with the second laminated battery cell is subjected to a hydrophilic treatment, and then the first laminated battery cell and the second laminated battery cell are overlapped with each other. It includes joining the first laminated battery cell and the second laminated battery cell by pressing while heating in a combined state.

In the above manufacturing method, the first and second laminated battery cells are joined to each other and physically integrated. This makes it possible to fix the mutual positions of the first and second laminated battery cells without using a fixing member such as an adhesive tape. Therefore, it is possible to improve the assemblability while avoiding an increase in the weight and volume of the module.

It is a side view which shows typically the outer shape of the laminated type battery module which concerns on one Embodiment. It is sectional drawing of the main part schematically showing the interface between adjacent laminated battery cells.

Hereinafter, preferred embodiments of the manufacturing method disclosed herein will be described with reference to the drawings as appropriate. Matters other than those specifically mentioned in the present specification and necessary for implementation can be grasped as design matters of those skilled in the art based on the prior art in the art. The manufacturing method disclosed herein can be carried out based on the contents disclosed in the present specification and the common general technical knowledge in the art.
Further, in the following drawings, members / parts having the same function may be designated by the same reference numerals, and duplicate explanations may be omitted or simplified. The dimensional relationships (length, width, thickness, etc.) in each figure do not necessarily reflect the actual dimensional relationships.
Further, in the present specification, the notation of "A to B (where A and B are arbitrary values)" indicating the range means A or more and B or less.

Here, the configuration of the laminated battery module will be described first, and then the manufacturing method of the laminated battery module according to the embodiment will be described.

<Laminated battery module>
FIG. 1 is a side view schematically showing the outer shape of a laminated battery module (hereinafter, may be simply referred to as a “module”) 100 according to an embodiment. FIG. 2 is a cross-sectional view of a main part schematically showing an interface between adjacent laminated battery cells 1. Note that FIG. 2 omits the illustration of the structure of the electrode body 20. Further, in FIGS. 1 and 2, reference numeral X indicates an arrangement direction of the laminated battery cells 1.

The module 100 includes a plurality of laminated battery cells (hereinafter, may be simply referred to as “battery cells”) 1, a pair of end plates 50A and 50B, and a plurality of restraint bands 52.
In the present specification, the "laminated battery cell" refers to a general battery having a structure in which a laminated film is used as an exterior body and an electrode body is housed inside the laminated film. The laminated battery cell may be, for example, a storage battery (secondary battery) such as a lithium ion secondary battery or a nickel hydrogen battery, or may be a storage element such as an electric double layer capacitor.

The plurality of battery cells 1 have the same shape here. The plurality of battery cells 1 have a flat plate shape. The plurality of battery cells 1 each have a pair of flat wide surfaces, and are arranged along the arrangement direction X (left-right direction in FIG. 1) so that the wide surfaces face each other. In other words, for example, a heat radiating member, a heat conductive member, a spacer member, an insulating member, and the like are not arranged between the plurality of battery cells 1. The even-numbered battery cells 1 in the arrangement direction X are arranged in a state of being rotated by 180 ° with respect to the odd-numbered battery cells 1 in the arrangement direction X. The number of battery cells 1 constituting the module 100 is 5, but is not limited to this. The number of battery cells 1 constituting the module 100 may be typically 10 or more, for example, about 10 to 100.

A positive electrode terminal 1a and a negative electrode terminal 1b project from the outer surface of each battery cell 1. The positive electrode terminal 1a and the negative electrode terminal 1b extend from the inside to the outside of the laminated film exterior body 10. Here, the positive electrode terminal 1a and the negative electrode terminal 1b of the battery cells 1 adjacent to each other in the arrangement direction X are electrically connected. As a result, the plurality of battery cells 1 are connected in series.

The configuration of the battery cell 1 may be the same as the conventional one, and is not particularly limited. The battery cell 1 is an all-solid-state battery here. The battery cell 1 includes a laminating film exterior body 10 and an electrode body 20 housed inside the laminating film exterior body 10. The laminating film exterior body 10 has a bag shape, and the peripheral edge of the storage space accommodating the electrode body 20 is heat-welded (heat-sealed) to be sealed.

The laminating film exterior body 10 is an insulating container that houses the electrode body 20. The structure of the laminated film exterior body 10 may be the same as that conventionally known, and is not particularly limited. The laminated film exterior 10 is typically made of a laminated film having a multi-layer structure. The laminated film exterior body 10 of the present embodiment has a three-layer structure, and the sealant layer 11, the gas barrier layer 12, and the protective layer (outer layer) 13 are laminated in this order from the side close to the electrode body 20. ing.

The sealant layer 11 is a layer for enabling heat welding. The sealant layer 11 is located on the innermost layer of the laminated film exterior body 10, that is, on the side closest to the electrode body 20. The sealant layer 11 is made of, for example, a thermoplastic resin. Examples of the thermoplastic resin include crystalline resins such as polyolefins such as polyethylene (PE) and polypropylene (PP); polyesters such as polyethylene terephthalate (PET); and non-crystalline resins such as polystyrene and polyvinyl chloride. Be done. Among them, crystalline resins, particularly polyolefins, are preferable from the viewpoint of exerting the effects of the techniques disclosed herein at a higher level.

The gas barrier layer 12 is a layer that blocks the inflow and outflow of moisture, air, or gas generated inside the battery cell 1 inside and outside the battery cell 1. The gas barrier layer 12 is made of a metal material such as aluminum, iron, or stainless steel. Of these, aluminum is preferable from the viewpoint of cost and weight reduction. The gas barrier layer 12 may be, for example, an aluminum foil or an aluminum-deposited layer.

The protective layer 13 is a layer for improving the durability of the laminated film exterior body 10. The protective layer 13 is located on the outer surface side of the gas barrier layer 12. The protective layer 13 may be the outermost layer of the laminated film exterior body 10. The protective layer 13 is made of, for example, polyester such as PET, polyamide (nylon), or the like.

In this embodiment, as an example, a case where the laminated film exterior body 10 has a three-layer structure composed of a sealant layer 11, a gas barrier layer 12, and a protective layer 13 has been described. However, the multilayer structure of the laminated film exterior body 10 may be 4 or more layers, for example, 4 to 10 layers. As an example, an adhesive layer for adhering both layers to each other may be provided between the layers described above. The adhesive layer may be made of a resin such as polyamide (nylon). Further, as another example, a printing layer, a flame retardant layer, a surface protective layer and the like may be further provided on the protective layer 13 as, for example, the outermost layer.

The electrode body 20 includes a positive electrode, a negative electrode, and a solid electrolyte layer (not shown). The solid electrolyte layer is interposed between the positive electrode and the negative electrode in the arrangement direction X. The configuration of the electrode body 20 may be the same as that conventionally known, and is not particularly limited. The electrode body 20 is typically a laminated electrode body (laminated electrode body) in which a rectangular positive electrode and a rectangular negative electrode are stacked in the arrangement direction X via a solid electrolyte layer. However, the electrode body 20 may be a wound type electrode body (wound electrode body) in which a band-shaped positive electrode and a band-shaped negative electrode are stacked via a solid electrolyte layer and wound in the longitudinal direction. .. Further, the electrode body 20 may further include a layer such as an insulating layer on the surface of the positive electrode and / or the negative electrode, for example.

The positive electrode may include a positive electrode current collector and a positive electrode active material layer fixed to the positive electrode current collector. The positive electrode current collector is a conductive member made of a metal having good conductivity, for example, aluminum. The positive electrode active material layer contains at least a positive electrode active material capable of reversibly occluding and releasing charge carriers. The positive electrode active material is a lithium transition metal composite oxide such as a lithium nickel cobalt manganese composite oxide. The positive electrode active material layer may further contain other components such as a solid electrolyte material described later, a conductive material, a binder and the like.

The negative electrode may include a negative electrode current collector and a negative electrode active material layer fixed to the negative electrode current collector. The negative electrode current collector is a conductive member made of a metal having good conductivity, for example, copper. The negative electrode active material layer contains at least a negative electrode active material capable of reversibly occluding and releasing charge carriers. The negative electrode active material is a carbon material such as graphite. The negative electrode active material layer may further contain other components such as a solid electrolyte material described later, a binder, a thickener and the like.

The solid electrolyte layer contains a solid electrolyte material having ionic conductivity. The solid electrolyte material may be crystalline or amorphous (glassy). When the battery cell 1 is a lithium ion secondary battery, the solid electrolyte layer contains a solid electrolyte material having Li ion conductivity. Examples of the solid electrolyte material having Li ion conductivity include sulfide-based solid electrolytes such as Li ₂ SP ₂ S ₅ series and Li ₂ S-SiS ₂ series, La _0.51 Li _0.34 TiO _2. Examples thereof include oxide-based solid electrolytes such as ₉₄ , Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ .

In this embodiment, as an example, a case where the battery cell 1 is an all-solid-state battery has been described. However, the battery cell 1 may be, for example, a liquid-based secondary battery having a liquid electrolyte (electrolyte solution). In that case, the electrode body 20 may have a configuration in which the positive electrode and the negative electrode face each other via an insulating member such as a separator. Further, in addition to the electrode body 20, an electrolytic solution may be housed inside the laminated film exterior body 10. The electrolytic solution may contain, for example, a non-aqueous solvent such as carbonates and esters, and a supporting salt such as a lithium salt that produces a charge carrier.

The pair of end plates 50A and 50B are arranged at both ends of the module 100 in the arrangement direction X (front-back direction in FIG. 1). The end plates 50A and 50B sandwich a plurality of battery cells 1 in the arrangement direction X. The plurality of restraint bands 52 are fixed to the end plates 50A and 50B by the plurality of screws 54. Each of the plurality of restraint bands 52 is attached so that a predetermined restraint pressure is applied to the arrangement direction X. As a result, a load is applied to the plurality of battery cells 1 from the arrangement direction X, and the modules 100 are integrally held. In the present embodiment, the plurality of battery cells 1 are constrained by the end plates 50A and 50B, the plurality of restraint bands 52, and the plurality of screws 54. However, the restraint mechanism is not limited to this.

As shown in FIG. 2, in the module 100 of the present embodiment, the laminated film exterior bodies 10 of the adjacent battery cells 1 are in contact with each other. A hydrophilic portion 13a is provided on a portion where the laminated film exterior bodies 10 are in contact with each other, here, on the surface of a protective layer 13 which is the outermost layer of one of the laminated film exterior bodies 10. Then, the adjacent battery cells 1 are joined to each other via the hydrophilic portion 13a. As a result, the adjacent battery cells 1 are physically integrated with each other. In other words, the adjacent battery cells 1 are joined together. In addition, in this specification, "joining" means having integrity to the extent that it does not fall when it is turned upside down.
Hereinafter, a method for manufacturing such a module 100 will be described.

<Manufacturing method of laminated battery module>
In the manufacturing method disclosed herein, at least the wide surface of the first battery cell 1 in the arrangement direction X, that is, the portion in contact with the second battery cell 1 is subjected to a hydrophilization treatment, and then the first and second batteries are used. The cells 1 are overlapped with each other and pressed while being heated to join each other. Other than this, the conventional general construction process can be adopted as appropriate. The manufacturing method of the present embodiment has the following three steps: (1) a preparation step of preparing the first and second battery cells 1; (2) hydrophilization of the surface of the first battery cell 1. The processing step; (3) a heating and pressing step of pressing the first battery cell 1 and the second battery cell 1 while heating them; is included. In addition to these steps, it is not hindered to include other steps at any stage. Hereinafter, each step will be described in order.

(1) In the preparation step, the first and second battery cells 1 are prepared. Each of the first and second battery cells 1 accommodates the electrode body 20 inside the laminated film exterior body 10, and then heat-welds (heat seals) the peripheral edge of the accommodation space containing the electrode body 20 to seal the cells 1. By doing so, it can be produced. The laminated film exterior body 10 can be prepared, for example, by purchasing a commercially available product. The electrode body 20 is, for example, in the following step: a step of applying a positive electrode slurry containing a positive electrode active material, a solid electrolyte material, and a solvent onto a positive electrode current collecting foil and drying the electrode body 20 to prepare a positive electrode; a negative electrode active material. A step of applying a negative electrode slurry containing a solid electrolyte material and a solvent onto a negative electrode current collector foil and drying the negative electrode slurry to prepare a negative electrode; a solid on the surface of the positive electrode and / or the negative electrode or the carrier sheet prepared above. Produced by a manufacturing method including a step of forming a solid electrolyte layer containing an electrolyte material; a step of laminating the positive electrode and the negative electrode with the solid electrolyte layer interposed therebetween and pressing and pressing from the stacking direction. can do.

(2) In the hydrophilization treatment step, the wide surface of the battery cell 1 in the arrangement direction X, specifically, the surface of the protective layer 13 of the laminating film exterior body 10 is hydrophilized. In addition, in this specification, "hydrophilic treatment" refers to all treatments which improve the hydrophilicity by modifying the surface of the protective layer 13. That is, a treatment in which the hydrophilicity of the protective layer 13 is enhanced by the treatment as compared with that before the treatment. The hydrophilization treatment is, for example, a chemical treatment in which an oxygen-containing group containing oxygen (O) such as a hydroxyl group or a carboxyl group is introduced into the surface of the protective layer 13. The hydrophilicity of the protective layer 13 can be grasped by, for example, the static contact angle (wetting property) of water.

In this step, the region (range) to be subjected to the hydrophilization treatment is set to include the region in contact with the second battery cell 1 in the heating and pressing step described later. The region to be hydrophilized may be set to be equal to or larger than the surface area of the wide surface of the second battery cell 1. However, it may be set smaller than the surface area of the wide surface of the second battery cell 1. In a plan view, the hydrophilization treatment may be applied to, for example, the entire surface of the protective layer 13 or may be applied to the same size as the surface area of the wide surface of the second battery cell 1. The hydrophilization treatment may be continuously applied to the surface of the protective layer 13, or may be discontinuously applied such as dots or stripes. Further, the hydrophilization treatment may be applied not only to the wide surface of the first battery cell 1 but also to the wide surface of the second battery cell 1.

The method of hydrophilization treatment may be the same as that conventionally known, and is not particularly limited. The hydrophilization treatment supplies the surface of the protective layer 13 with oxygen-containing chemical species such as oxygen gas (O ₂ ), ozone (O ₃ ), oxide ions (O ^2- ), oxygen radicals, and oxygen plasma. It is a process including that. Specific examples of the hydrophilization treatment include corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, ozone treatment and the like. Among them, the corona discharge treatment is convenient and preferable.

The corona discharge treatment can be performed using, for example, a general corona discharge treatment device such as a spark gap method, a vacuum tube method, or a solid state method. In one example of a corona discharge processing device, a voltage is applied between a discharge electrode and a grounded counterpole dielectric roll to generate a corona discharge. The conditions of the corona discharge treatment may be appropriately adjusted so as to impart desired hydrophilicity to the surface of the protective layer 13, and are not particularly limited. As an example, the corona discharge density may be set to approximately 5 to 50 W / m ² / min, for example 10 ± 5 W / m ² / min. Further, the processing time may be generally within 10 minutes, typically within 5 minutes, for example, 0.1 seconds to 1 minute, from the viewpoint of productivity and cost.
As described above, the surface of the battery cell 1, here, the surface of the protective layer 13 of the laminated film exterior body 10 can be subjected to a hydrophilic treatment to form the hydrophilic portion 13a.

(3) In the heating and pressing step, first, the first and second battery cells 1 are opposed to each other, and the laminated film exterior bodies 10 are overlapped with each other. At this time, the hydrophilic portion 13a of the protective layer 13 is interposed between the first and second battery cells 1. Next, while heating the first and second battery cells 1, the first and second battery cells 1 are pressed from the overlapping direction (X direction in FIG. 2). The heating and pressing conditions may be appropriately adjusted so that the first and second battery cells 1 are joined to each other, and are not particularly limited. As an example, the heating temperature can be approximately 40 ° C. or higher, typically 40-80 ° C., for example 60 ± 10 ° C. The pressure at the time of pressing (pressing pressure) can be approximately 5 MPa or more, typically 10 to 100 MPa, for example, 30 ± 10 MPa.
As described above, the first and second battery cells 1 can be joined to obtain a joined body in which these are physically integrated. The bonded body may be in a form in which two battery cells 1 are joined to each other in the arrangement direction X, or may be in a form in which three or more battery cells 1 are continuously joined.

Then, typically, after repeating the steps (1) to (3) a plurality of times to prepare a plurality of the bonded bodies, these are sandwiched between the end plates 50A and 50B from the arrangement direction X, and the plurality of restraint bands 52 are formed. And a plurality of screws 54 are used for restraint. As described above, the module 100 in which the first laminated battery cell 1 and the second laminated battery cell 1 are arranged adjacent to each other in the arrangement direction X can be manufactured.

As described above, in the above manufacturing method, after forming the hydrophilic portion 13a on the protective layer 13 of at least the first battery cell 1, the first and second battery cells 1 are joined via the hydrophilic portion 13a to physically form the protective layer 13. To be integrated. This makes it possible to fix the mutual positions of the first and second battery cells 1 without using an adhesive tape or an adhesive fixing member. Therefore, it is possible to improve the assemblability of the module 100 while avoiding an increase in weight and volume. As a result, the productivity of the module 100 can be increased and the production cost can be reduced. Further, the module 100 can be made lighter or space-saving to improve the battery characteristics (for example, battery capacity) per unit weight or unit volume.

Further, in the module 100, the mutual positional relationship between the first and second battery cells 1 is unlikely to change even when vibration, impact, or the like is applied from the outside. According to the studies by the present inventors, this makes it difficult for the constraining pressure with respect to the electrode body 20 to change over time as compared with the conventional laminated battery module. As a result, the variation in resistance (resistance unevenness) between the battery cells 1 is suppressed to a small extent, and the battery performance can be stably exhibited. Therefore, high durability can be realized.

The module 100 can be used for various purposes, and can be suitably used, for example, as a power source (driving power source) for a motor mounted on a vehicle. The type of vehicle is not particularly limited, but typically examples thereof include automobiles, for example, plug-in hybrid vehicles (PHVs), hybrid vehicles (HVs), electric vehicles (EVs), and the like.

Although the present invention has been described in detail above, the above-described embodiment is merely an example, and the invention disclosed herein includes various modifications and modifications of the above-mentioned specific examples.

1 Laminated battery cell (battery cell)
10 Laminated film exterior body 13 Protective layer 13a Hydrophilic part 100 Laminated battery module (module)

Claims (1)

A method for manufacturing a laminated battery module in which a first laminated battery cell and a second laminated battery cell are arranged next to each other and electrically connected to each other.
After hydrophilization treatment is performed on both the portion of the first laminated battery cell in contact with the second laminated battery cell and the portion of the second laminated battery cell in contact with the first laminated battery cell . The first laminated type battery cell and the second laminated type battery cell are joined to each other by pressing while heating the first laminated type battery cell and the second laminated type battery cell in a state of being overlapped with each other. Include,
How to manufacture a laminated battery module.

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