JP6351930B2 - Method for producing multilayer membrane electrode assembly - Google Patents

Description

  The present invention relates to a method for producing a multilayer membrane electrode assembly used for a lithium ion secondary battery or the like and a laminated battery.

Generally, a lithium ion secondary battery includes a positive electrode plate coated with a positive electrode active material on a current collector and a negative electrode plate coated with a negative electrode active material on a current collector, with a separator interposed therebetween. The multilayer membrane electrode assembly in which the positive electrode plate, the separator and the negative electrode plate are laminated is sealed in the case together with the electrolyte solution, and the positive electrode plate and the negative electrode plate of the multilayer membrane electrode assembly are respectively sealed. The connected terminal tab protrudes from the case and is schematically configured.
In recent years, polymer lithium ion secondary batteries have been developed as secondary batteries for the purpose of reducing the size and weight and improving safety. This is a gel electrolyte used in place of the electrolyte used in the conventional lithium ion secondary battery. As a manufacturing method of this polymer lithium ion secondary battery, for example, a method disclosed in Patent Document 1 below has been proposed.

  In the method for producing a polymer lithium secondary battery described in Patent Document 1, a non-aqueous electrolyte solution is provided between a non-aqueous electrolyte non-impregnated positive electrode plate and a non-aqueous electrolyte non-impregnated negative electrode plate formed in a sheet shape. A unit cell is formed by laminating a sheet-like positive electrode plate and a negative electrode plate so that an unimpregnated separator is interposed. Then, the obtained unit cell is sealed with an exterior material made of a laminate film, leaving a part of the opening, and then the non-aqueous electrolyte is injected into the exterior material from the opening to seal the opening. It is a polymer lithium secondary battery.

JP 2001-76760 A

  By the way, according to the method of manufacturing a multilayer membrane electrode assembly of Patent Document 1, a positive electrode plate and a negative electrode plate formed in a sheet shape are accurately positioned by interposing a sheet-like separator therebetween. However, there is a problem that the work of laminating the positive electrode plate and the negative electrode plate is complicated and the work efficiency is poor. Further, since the electrolyte layer is formed by injecting the nonaqueous electrolyte from the opening of the exterior material, it takes a long time to inject and age the nonaqueous electrolyte, and the production efficiency of the polymer lithium secondary battery is poor. There was a problem.

  Then, in view of the said problem, this invention makes it a subject to provide the manufacturing method of the multilayer membrane electrode assembly which can laminate | stack a positive electrode plate, an electrolyte layer, and a negative electrode plate simply and for a short time.

The present invention, while interposing an electrolyte layer between the positive and negative electrode plates, in the manufacturing method of the multi-layer membrane electrode assembly which is formed by laminating with these positive and negative electrode plates alternately, a strip One electrode plate extending step of extending and extending any one of the positive electrode plate formed and the negative electrode plate formed in a strip shape, and both plate surfaces of the one electrode plate formed in a strip shape An electrolyte layer is formed by forming an electrolyte layer by coating an electrolyte solution on the surface, or forming an electrolyte layer by disposing a solid electrolyte, and the other electrode plate extending step of extending and extending the other electrode plate And bonding the strip-shaped positive electrode plate and the strip-shaped negative electrode plate , cutting the bonded strip-shaped positive electrode plate, the electrolyte layer, and the strip-shaped negative electrode plate at a predetermined interval to form a unit cell, comprising a stacking step of stacking the unit cells, wherein the other In this electrode plate, one plate surface is opposed to one plate surface of the one electrode plate, and further downstream from the position where the electrolyte layer is formed on the one electrode plate. The one electrode plate and the other electrode plate are stacked in a flat plate shape, respectively.
Further, the present invention provides a method for producing a multilayer membrane electrode assembly formed by alternately laminating these positive electrode plates and negative electrode plates while interposing an electrolyte layer between the positive electrode plate and the negative electrode plate. Both of the positive electrode plate formed in a strip shape and the one negative electrode plate formed in a strip shape are extended by extending one electrode plate, and the one electrode plate formed in the strip shape. An electrolyte layer forming step of forming an electrolyte layer by applying an electrolytic solution to the plate surface to form a gel electrolyte layer or a solid electrolyte, and extending the other electrode plate to extend the other electrode plate And bonding the band-shaped positive electrode plate and the band-shaped negative electrode plate, and bonding the band-shaped positive electrode plate, the electrolyte layer, and the band-shaped negative electrode plate so that the positive electrode plate is located inside. And the other electrode plate includes: The other plate surface is made to face one plate surface of the one electrode plate, and the one electrode plate is drawn further downstream from the position where the electrolyte layer is formed. It is characterized by being.
According to the present invention, the electrolytic solution is applied to the surface of the extended strip-shaped electrode plate to form a gel electrolyte layer, or the solid electrolyte is disposed. The electrolyte layer can be continuously formed on the plate surface simply and in a short time.
And in the state which interposed the electrolyte layer between the positive electrode plate and the negative electrode plate, in order to cut | disconnect or wind a strip | belt-shaped positive electrode plate and a strip | belt-shaped negative electrode plate simultaneously, the positive electrode plate and negative electrode which interposed the electrolyte layer A multilayered membrane electrode assembly of a plate can be easily produced.

The present invention includes a separator disposing step of arranging a separator formed in a strip shape on the plate surface of one electrode plate formed in the strip shape or on the plate surface of the other electrode plate formed in the strip shape. Is desirable.
According to the present invention, the separator disposed between the positive electrode plate and the negative electrode plate can be easily arranged on the same line as the positive electrode plate and the negative electrode plate.

In the electrolyte layer forming step, the present invention forms an electrolyte layer by applying an electrolyte solution to the respective plate surfaces of the positive electrode plate and the negative electrode plate to form a gel electrolyte or by disposing a solid electrolyte. It is desirable.
According to the present invention, each of the positive electrode plate and the negative electrode plate can be efficiently impregnated with the electrolytic solution.

The present invention preferably includes an electrolyte heating step of heating the positive electrode plate and / or the negative electrode plate by induction heating after the bonding step of bonding the belt-shaped positive electrode plate and the belt-shaped negative electrode plate.
According to the present invention, the current collector of the positive electrode plate and / or the negative electrode plate is heated by induction heating, and the gel electrolyte or solid electrolyte is heated from the vicinity of the current collector to form the positive electrode plate and / or the negative electrode plate. The gel electrolyte or solid electrolyte can be blended efficiently.

  According to the method for manufacturing a multilayer membrane electrode assembly according to the present invention, a multilayer membrane electrode assembly can be easily manufactured, and the manufacturing time can be greatly reduced. The production efficiency can be improved.

It is the perspective view which showed typically the multilayer membrane electrode assembly manufactured using the manufacturing method shown as the 1st Embodiment of this invention. FIG. 2 is a cut positive electrode plate and a negative electrode plate in a multilayer membrane electrode assembly manufactured using the manufacturing method of the first embodiment of the present invention, where (a) is a positive electrode plate and (b) is a negative electrode plate. It is the shown top view. It is the schematic explanatory drawing which showed the manufacturing method shown as the 1st Embodiment of this invention. It is the schematic explanatory drawing which showed the modification of the manufacturing method shown as the 1st Embodiment of this invention. It is the schematic explanatory drawing which showed the manufacturing method shown as the 2nd Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view showing a schematic configuration of a multilayer membrane electrode assembly 1 manufactured by the manufacturing method of the first embodiment of the present invention.

As shown in FIG. 1, a multilayer membrane electrode assembly 1 which is a target of the manufacturing method of the first embodiment of the present invention is a solid or gel electrolyte layer (in this figure, coated with an electrolyte solution). A positive electrode plate 2a on which an electrolyte solution (not shown) is formed and a negative electrode plate 3a on which a solid or gel electrolyte layer (not shown in the figure) is formed by applying an electrolyte solution are alternately laminated, The terminal tab (first terminal tab) 4 is projected from the end of 2a, and the terminal tab (second terminal tab) 5 is projected from the end of the negative electrode plate 3a. is there.

  As shown in FIG. 2A, the cut-out positive electrode plate 2a has a positive electrode active material layer 8 on both sides of the current collector 6 made of an aluminum foil formed in a substantially rectangular shape, leaving the end portions 7 and 7. Formed. The end 7 serves as a joining margin for the terminal tab 4.

  The positive electrode active material layer 8 is composed of, for example, a positive electrode active material, a conductive slurry, and a positive electrode slurry in which a binder serving as a binder is dispersed in a solvent. It is applied to both sides between 7.

As the positive electrode active material, for example, a metal acid lithium compound represented by the general formula LiMxOy (where M is a metal and x and y are composition ratios of the metal M and oxygen O) is used.
Specifically, lithium cobaltate, lithium nickelate, lithium manganate, lithium iron phosphate and the like are used as the metal acid lithium compound.
Acetylene black or the like is used as the conductive assistant, and polyvinylidene fluoride or the like is used as the binder.

  The terminal tab 4 of the positive electrode plate 2a is provided so as to be joined to the end portion 7 of the positive electrode plate 2a so as to protrude outward, and is formed of aluminum or the like, for example.

  Further, as shown in FIG. 2B, the cut-out negative electrode plate 3a is formed on the current collector 10 made of, for example, copper (Cu) formed in a substantially rectangular shape, and the negative electrode active material is formed on both surfaces with the end 11 remaining. The layer 12 is formed. The end portion 11 serves as a joining margin for the terminal tab 5.

The negative electrode active material layer 12 is composed of, for example, a negative electrode active material, a binder serving as a binder, and a negative electrode slurry obtained by dispersing a conductive additive added as necessary in a solvent. It is applied to both surfaces between the end portions 11 and 11 of the body 10.
As the negative electrode active material, for example, a carbon material made of carbon powder or graphite powder, or a metal oxide such as lithium titanate is used.
For example, polyvinylidene fluoride or the like is used as the binder, and acetylene black or the like is used as the conductive auxiliary agent.
The terminal tab 5 of the negative electrode plate 3a is provided so as to be joined to the end portion 11 and protrude outward, and is formed of nickel or the like, for example.

  The electrolyte layer 13 shown in FIG. 3 is obtained by gelling or solidifying the electrolytic solution 13a applied to both plate surfaces of the strip-shaped negative electrode plate 3. The electrolyte layer 13 is more preferably provided on both plate surfaces of the strip-like positive electrode plate 2 and negative electrode plate 3.

  The electrolytic solution 13a is made of, for example, a polymer matrix and a non-aqueous electrolyte solution (that is, a non-aqueous solvent and an electrolyte salt), and is gelled to cause stickiness on the surface. Or an electrolyte solution consists of a polymer matrix and a non-aqueous solvent, and becomes a solid electrolyte. Whichever electrolyte is used, one having adhesiveness when the electrolyte is applied to the positive electrode plate 2 or the negative electrode plate 3 is used. Further, the electrolytic solution preferably forms a self-supporting film that does not separate from the plate surface of the positive electrode plate 2 or the negative electrode plate 3.

  The polymer matrix includes polyvinylidene fluoride (PVDF), hexafluoropropylene copolymer (PVDF-HFP), polyacrylonitrile, alkylene ethers such as polyethylene oxide and polypropylene oxide, polyester, polyamine, polyphosphazene, polysiloxane Etc. are used.

  The non-aqueous solvent is a lactone compound such as γ-butyrolactone; a carbonic acid ester compound such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, or methyl ethyl carbonate; a carboxylic acid ester compound such as methyl formate, methyl acetate, or methyl propionate; Ether compounds such as tetrahydrofuran and dimethoxyethane; ether compounds such as tetrahydrofuran and dimethoxyethane; nitrile compounds such as acetonitrile; sulfone compounds such as sulfolane; amide compounds such as dimethylformamide; .

When the electrolyte solution 13a is used as a solid electrolyte layer, it is prepared by mixing a nitrile compound such as acetonitrile; an ether compound such as tetrahydrofuran; and an amide compound such as dimethylformamide alone or in combination of two or more.
The electrolyte salt is not particularly limited, and lithium salts such as lithium hexafluorophosphate, lithium perchlorate, and lithium tetrafluoroborate can be used.

  A non-woven fabric or the like is used for the separator 14.

Next, a method for manufacturing the multilayer membrane electrode assembly 1 according to the first embodiment of the present invention will be described with reference to FIGS. 2 (a), 2 (b), and 3. FIG. The manufacturing method of this multilayer membrane electrode assembly 1 includes the following steps.
(I) The strip-shaped negative electrode plate 3 in which the negative electrode active material layers 12 are formed on both plate surfaces of the current collector 10 is extended in one direction (arrow P) and can be conveyed in the direction of arrow P. Step <State of Negative Electrode Plate Extension (One Electrode Plate Extension Step)>
(II) A state in which the positive electrode plate 2 in which the positive electrode active material layers 8 are formed on both plate surfaces of the current collector 6 is extended in one direction (arrow P) and can be conveyed in the arrow P direction. <Positive electrode plate extending step (the other electrode plate extending step)>
(III) Step of applying electrolyte solution 13a on both plate surfaces of negative electrode plate 3 formed in a strip shape to form gel-like or solid electrolyte layer 13 <Electrolyte layer forming step>
(IV) Step of placing the separator 14 formed in a strip shape on both plate surfaces of the negative electrode plate 3 formed in a strip shape <Separator placement step>
(V) The positive electrode plate 2 and the negative electrode plate 3 are bonded and laminated with the electrolyte layer 13 and the separator 14 interposed therebetween, and the laminated positive electrode plate 2, separator 14 and negative electrode plate 3 are spaced at a predetermined interval. A process of cutting the rectangular unit cell 1a and laminating the unit cells 1a <Lamination process>

(I) Negative electrode plate extending step (one electrode plate extending step)
In the negative electrode plate extending step, a strip-shaped negative electrode plate 3 prepared in advance is used.
As the negative electrode plate (one electrode plate) 3, a current collector 10 formed in a strip shape using a copper foil or the like is used. On both plate surfaces of the current collector 10, the negative electrode slurry is applied, leaving the end portions 11, 11 in the width direction, and dried to form a strip-shaped negative electrode plate 3 provided with the negative electrode active material layer 12. The strip-shaped negative electrode plate 3 is wound in a roll shape. The terminal tab 5 is welded to the end portions 11 and 11 of the current collector 10 where the negative electrode active material layer 12 is not provided at a predetermined interval.
Then, the negative electrode plate 3 formed as described above is extended in one direction (arrow P) to extend a predetermined dimension (L1).

(II) Positive electrode plate extending step (the other electrode plate extending step)
In the positive electrode plate extending step, a belt-shaped positive electrode plate 2 prepared in advance is used.
For the positive electrode plate 2 (the other electrode plate), a current collector 6 formed in a strip shape using an aluminum foil or the like is used. On both plate surfaces of the current collector 6, a positive electrode slurry is applied, leaving the end portions 7, 7 in the width direction, and dried to form a strip-like positive electrode plate 2 provided with a positive electrode active material layer 8. The belt-like positive electrode plate 2 is wound in a roll shape. The terminal tab 4 is welded to the end portions 7 and 7 of the current collector 6 on which the positive electrode active material layer 8 is not provided at a predetermined interval.
Then, the positive electrode plate 2 formed as described above is fed out from a position downstream of the feeding start position of the negative electrode plate 3 by a predetermined dimension L2, and one plate surface is made to face the plate surface of the negative electrode plate 3 to be predetermined. Extend dimension (L3).
The positive electrode plate 2 and the negative electrode plate 3 are preferably dried by sufficiently removing water before the electrolyte layer forming step described later, so that the electrolyte solution 13a can be applied satisfactorily.

(III) Electrolyte Layer Formation Step On the upstream side of the feeding start position of the positive electrode plate 2, the electrolyte solution 13 a is applied to both plate surfaces of the negative electrode plate 3, and the applied electrolyte solution 13 a is cooled to form a gel or A solid electrolyte layer 13 is formed.
(IV) Separator Arrangement Step A separator 14 formed in a band shape is disposed on both plate surfaces of the negative electrode plate 3 formed in a band shape. In addition, the arrangement | positioning of the separator 14 may be any timing before and behind the electrolyte layer formation process mentioned above.

(V) Laminating Step In the laminating step, the positive electrode plate 2 and the negative electrode plate 3 that are arranged to face each other with the electrolyte layer 13 and the separator 14 interposed therebetween are laminated by rollers R and R, and the positive electrode is laminated. The plate 2, the electrolyte layer 13, the separator 14 and the negative electrode plate 3 are cut at a predetermined interval in a direction (depth direction in the drawing) perpendicular to one direction (arrow P direction) and a rectangular sheet-like unit cell 1a To do. Then, a plurality of unit cells 1 a obtained are stacked to form a multilayer membrane electrode assembly 1.
At this time, it is preferable to heat the electrolyte layer 13 so that the gel electrolyte penetrates into the positive electrode active material layer and the negative electrode active material layer. As a heating method, non-contact heating such as hot air heating using a resistance heater and air blowing, far-infrared heating using a ceramic heater, lamp heater, microplasma heating, induction heating, and the like can be applied.

  As described above, the multilayer membrane electrode assembly 1 in which the positive electrode plate 2a is disposed on the negative electrode plate 3a and the gel electrolyte layer 13 and the separator 14 are interposed between the positive electrode plate 2a and the negative electrode plate 3a. Is formed. Moreover, the multilayered membrane electrode assembly 1 can be continuously produced while the belt-like positive electrode plate 2 and the negative electrode plate 3 are conveyed in the direction of arrow P.

  In this case, it is desirable to laminate so that the negative electrode plate 3 is located in the lowermost layer and the uppermost layer of the multilayer membrane electrode assembly 1. By forming the multilayer membrane electrode assembly 1, it is possible to prevent the occurrence of defects such as a short circuit by preventing the occurrence of lithium dendritic precipitates (dendrites) that can be generated by positioning the positive electrode plate 2 a as the outermost layer. can do. The dendrite shown on the left is generated when the positive electrode plate 2a is located in the outermost layer of the multilayer membrane electrode assembly 1 and faces the outside of the positive electrode plate 2a (that is, not facing the negative electrode plate 3a). Since the active material layer 8 is formed, the positive electrode plate 2a is positioned in the outermost layer without adjusting the number of both the positive electrode plate 2a and the negative electrode plate 3a of the multilayer membrane electrode assembly 1. However, by not forming the positive electrode active material layer 8 on the plate surface facing the outside of the positive electrode plate 2a located in the outermost layer, it is possible to prevent the generation of dendrites and avoid the possibility of causing problems such as a short circuit. it can.

  The multilayer membrane electrode assembly 1 obtained by the above method is packaged with an exterior material (not shown) such as a laminate film with the terminal tabs 4 and 5 protruding outward, and the outer periphery is sealed. Thus, a laminated battery such as a lithium ion secondary battery is obtained.

  As described above, according to the method for manufacturing a multilayer membrane electrode assembly 1 of the present invention, the positive electrode plate 2 formed in a strip shape and the negative electrode plate 3 formed in a strip shape are made to face each other. The gel-like or solid electrolyte layer 13 is formed by continuously applying the electrolytic solution 13a to both plate surfaces of the negative electrode plate 3 before being bonded to each other. .

  Therefore, for example, when the positive electrode plate 2 and the negative electrode plate 3 are cut into strips and then the electrolytic solution 13a is applied, the negative electrode plates 3a are held one by one and the electrolytic solution 13a is applied, and the positive electrode plate 2a Thus, it is possible to obtain the effect that the electrolyte layer 13 can be formed and laminated easily, reliably and in a short time, without the trouble of accurately aligning and bonding.

  In addition, as in the conventional method of manufacturing a multilayer membrane electrode assembly, the multilayer membrane electrode assembly enclosed in the exterior material is placed in a vacuum atmosphere, and an electrolyte is injected between the positive electrode plate and the negative electrode plate. The effect that the electrolyte layer can be efficiently formed without the labor and aging time of aging is obtained.

  Further, since the electrolytic solution 13a is applied to the plate surface of the extended strip-shaped negative electrode plate 3 to form a gel, the positive electrode of the electrolytic solution 13a is conveyed at an early timing during the transportation of the positive electrode plate 2 and the negative electrode plate 3. The penetration into the active material layer 8 and the negative electrode active material layer 12 can be started. Therefore, an effect that the lead time for producing the multilayer membrane electrode assembly 1 can be compressed is obtained.

  Further, the positive electrode plate 2, the electrolyte layer 13, the negative electrode plate 3 and the separator 14 can be laminated on one line, and the positive electrode plate 2, the separator 14 and the negative electrode plate 3 are simultaneously cut at one place. Therefore, the manufacturing apparatus of the multilayer membrane electrode assembly 1 can be made compact, and the effect that the installation space of the manufacturing apparatus can be reduced is obtained.

  Further, by applying the multilayer membrane electrode assembly 1 using the gel-like or solid electrolyte layer 13 to a laminated battery such as a lithium ion secondary battery, the laminated state is good and the liquid does not easily leak, and is manufactured. The effect that the suitable laminated battery which suppressed cost can be manufactured is acquired.

  In the above embodiment, the multilayer membrane electrode assembly 1 has a configuration in which a plurality of unit cells 1a formed by cutting the strip-shaped negative electrode plate 3 and the strip-shaped positive electrode plate 2 at predetermined intervals are stacked. However, as shown in FIG. 4, the belt-like negative electrode plate 3 and the belt-like positive electrode plate 2 may be bonded so that the positive electrode plate 2 is positioned inside.

  Moreover, in the said embodiment, although the electrolyte solution 13a which forms the gel-like electrolyte layer 13 was applied to both board surfaces of the strip | belt-shaped negative electrode plate 3, the said electrolyte solution 13a is each of the negative electrode plate 3 and the positive electrode plate 2. It may be applied to one plate surface, or both plate surfaces of both the negative electrode plate 3 and the positive electrode plate 2.

  Further, in the above embodiment, the positive electrode plate 2 is laminated on the upper surface of the negative electrode plate 3, but the positive electrode active material layer 8 is the plate surface or the uppermost layer of the multilayer membrane electrode assembly 1 facing outward. A configuration in which the negative electrode plate 3 is laminated on the upper surface of the positive electrode plate 2 may be used as long as it is not formed on the plate surface facing outward and generation of dendrites can be prevented.

  Moreover, as long as the negative electrode plate 3 and the positive electrode plate 2 can be appropriately laminated while interposing the electrolyte layer 13 and the separator 14, the negative electrode plate 3 and the positive electrode plate 2 may be bonded to each other from the horizontal direction. .

Next, a second embodiment of the present invention will be described with reference to FIG. In the present embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, description thereof is omitted, and only differences from the first embodiment will be described.
In this embodiment, the gel electrolyte 13 is applied to the separator 14 and bonded to the negative electrode plate 3, and the gel electrolyte 13 is applied to the separator 14 and bonded to the positive electrode plate 2. Or after interposing the separator 14 and the gel or solid electrolyte between the positive electrode plate 2 and the negative electrode plate 3, the positive electrode plate 2 and the negative electrode plate 3 are moved by an induction heating device (for example, heating by IH) 20. Each differs from the first embodiment in that it is induction heated.

  According to the manufacturing method of the present embodiment, the current collectors 6 and 10 (see FIG. 2) of the positive electrode plate 2 and the negative electrode plate 3 are heated, and the gel is located on the surface layer side away from the positive electrode plate 2 and the negative electrode plate 3. The electrolyte 13 can be prevented from melting and melted from the gel electrolyte 13 adjacent to the positive electrode plate 2 and the negative electrode plate 3, that is, the gel electrolyte 13 located inside the unit cell 1a. As a result, like the heating means such as hot air heating, the gel electrolyte 13 is melted from the surface layer side, and the whole is heated, so that the positive electrode active material layer 8 (see FIG. 2A) or the negative electrode active material layer (Refer to FIG. 2 (b)) Prevents the possibility of dripping during penetration into the gel-like electrolyte 13 in the vicinity of the positive electrode plate 2 and the negative electrode plate 3, and the positive electrode active material layer 8 or the negative electrode. The active material layer 12 can be effectively penetrated with a small amount of heat and in a short time.

In addition, in the state laminated | stacked like the separator 14-positive electrode plate 2 to which the separator 14-negative electrode plate 3-gel-like electrolyte 13 coated the gel-like electrolyte 13 was coated, the negative electrode plate 3 and the positive electrode plate 2 is preferably heated by induction heating from both sides of the negative electrode plate 3 side and the positive electrode plate 2 side. However, when sufficient heating is possible, the negative electrode plate 3 and the positive electrode plate 2 are placed with the separator 14 interposed therebetween. Induction heating may be performed from one direction.
Further, the gel electrolyte 13 or the solid electrolyte (not shown) may be disposed between the separator 14 and the positive electrode plate 2 and between the separator 14 and the negative electrode plate 3 and heated as described above. .

  Hereafter, the manufacturing method of the multilayer membrane electrode assembly by 2nd Embodiment is demonstrated concretely using an Example.

[Example 1]
A lithium ion secondary battery (multilayer membrane electrode assembly) similar to the multilayer membrane electrode assembly of FIG. 1 was produced according to the following specifications.

<Positive electrode plate>
A slurry for positive electrode was prepared using lithium iron phosphate (LiFePO ⁴ ) (weight 75 wt% or less), acetylene black 10 wt% (wt%) as a conductive additive, and polyvinylidene fluoride 15 wt% as a binder (binder), These were applied to both surfaces of a current collector (length 50 mm × width 100 mm) (thickness 15 μm) made of rolled aluminum foil and dried. Three types of positive electrode plates were prepared by pressurizing and compacting the positive electrode active material coated and dried on the current collector with a press machine at different pressures stepwise as shown in Table 1 below.

<Negative electrode plate>
Negative electrode slurry in which natural graphite (weight 75 wt% or less), binder (polyvinylidene fluoride) 15 wt% serving as a binder, and conductive additive (acetylene black) 10 wt% are dispersed in a solvent (water) are prepared. Was applied to both sides of a current collector (length 50 mm × width 100 mm) made of rolled copper foil 10 μm and dried. Three types of negative electrode plates were prepared by pressurizing and compacting the negative electrode active material coated and dried on the current collector with a press machine at different pressures stepwise as shown in Table 1 below.

<Gel electrolyte>
LiPF6 as an electrolyte is dissolved at 1 mol / L in a solvent in which ethylene carbonate (EC): diethyl carbonate (DEC): dimethyl carbonate (DMC) is blended at a ratio of 1: 1: 1 (weight ratio), and PVDF as a polymer component is 5 wt. A gelled electrolyte dissolved at a concentration of% was prepared.

<Separator>
A cellulose nonwoven fabric having a porosity of 70%, a density of 0.5 g / m ³ , and a thickness of about 20 μm was used.
<Heating equipment>
As an induction heating device, NT204 (manufactured by Nippon Thermonics) equipped with a spiral heating coil (φ200 mm) having a current of 3 A, a power source of 65 V, and a frequency of about 15 kHz was used.

<Production of laminate>
Nine pairs of positive electrode plates alternately coated with a gel electrolyte at a thickness of 30 μm and pressed at the same pressure as the negative electrode plates are applied to the surfaces of the three types of negative electrode plates produced as described above. A laminated body having an average electromotive force of 3.4 V 2A was prepared by bonding them so that the positive electrode plate and the negative electrode plate were 18 layers in total.
<Heat treatment>
Inductive heating was performed for 3 seconds at an interval of 10 mm from the electrode on the outermost surface of the laminate to obtain a multilayer membrane electrode assembly.

[Example 2]
<Laminate>
Three types of laminates similar to Example 1 were produced.
<Heating equipment>
The same induction heating apparatus as in Example 1 was used.
<Heat treatment>
The laminated body is conveyed at a speed of 5 m / min, and induction heating is performed at intervals of 10 mm from the electrode on the outermost surface for 3 seconds from the start to the end of heating by the heating coil to obtain a multilayer membrane electrode assembly. It was.

[Comparative Example 1]
<Laminate>
Three types of laminates similar to Example 1 were produced.
<Heating equipment>
As a heating device, a hot air dryer (manufactured by Takezuna Seisakusho) with a power of 5 kW and a power source of 200 V was used.
<Heat treatment>
Hot air heating was performed for 10 seconds at an air volume of 1 m ³ / min at an interval of 100 mm from the outermost surface of the laminate to obtain a multilayer membrane electrode assembly.

[Comparative Example 2]
<Laminate>
Three types of laminates similar to Example 1 were produced.
<Heating equipment>
As a heating device, a hot air dryer (manufactured by Takezuna Seisakusho) with a power of 5 kW and a power source of 200 V was used.
<Heat treatment>
Hot air heating was performed for 10 seconds at an air volume of 2 m ³ / min at an interval of 100 mm from the outermost surface of the laminate to obtain a multilayer membrane electrode assembly.

[Comparative Example 3]
<Laminate>
Three types of laminates similar to Example 1 were produced.
<Heating equipment>
As a heating device, a hot air drying furnace (manufactured by Taketsuna Manufacturing Co., Ltd.) having 5 kW, a power source of 200 V and a transport distance of 1 m was used.
<Heat treatment>
The laminated body is conveyed at a speed of 5 m / min, heated at a distance of 100 mm from the outermost surface, heated for 12 seconds from the start to the end in the hot air drying furnace at an air volume of 2 m ³ / min, A membrane electrode assembly was obtained.

[Comparative Example 4]
Three types of laminates similar to Example 1 were produced.
A multi-layer membrane electrode assembly was obtained without performing the heat treatment.

[Evaluation results]
As shown in Table 1, about the laminated body of Comparative Examples 1-3, since the obtained battery capacity is 0-4.5 Wh, the positive electrode active material and the negative electrode active material are increased by increasing the press pressure of the positive electrode plate and the negative electrode plate. It was found that when the density of the material was increased, the permeation of the gel electrolyte into the positive electrode active material and the negative electrode active material was not sufficiently performed, and the penetration was difficult.

  On the other hand, when the induction heating of Examples 1 and 2 was performed, the heat amount of the heating used in Comparative Examples 1 to 3 was smaller at any press pressure, and the heating time was shorter. In spite of being very short, it was found that a battery capacity far higher than those of Comparative Examples 1 to 4 was obtained, so that the permeation of the gel electrolyte into the positive electrode active material and the negative electrode active material was sufficiently performed. It was. In addition, when hot air heating was performed while conveying as in Comparative Example 3, the lower heat efficiency was lower than when the positive electrode plate and the negative electrode plate were kept stationary and hot air was applied intensively.

  That is, it was found that when induction heating is performed after the laminate is formed, the gel electrolyte can be efficiently infiltrated into the positive electrode active material and the negative electrode active material in a small amount of heat and in a short time. Furthermore, even if the press pressure of the laminate was increased, a battery capacity almost comparable to that obtained when the press pressure was low was obtained. Therefore, by using induction heating, the capacity of the battery can be easily increased. I understood. In addition, since heat is easily transferred by induction heating, even in the case of a so-called Roll to Roll manufacturing method for manufacturing a multilayer membrane electrode assembly while being conveyed, the heating efficiency is reduced without reducing the heating efficiency. It was possible to permeate the gel electrolyte by heating over time, and the superiority of induction heating was confirmed.

DESCRIPTION OF SYMBOLS 1 Multilayer membrane electrode assembly 2 Strip | belt-shaped positive electrode plate 2a Cathode plate 3 after cutting 3 Strip | belt-shaped negative electrode plate
3a The negative electrode plate after cutting
13 Gel electrolyte layer (electrolyte layer)
20 Heating device P One direction

Claims (5)

In the method for producing a multilayer membrane electrode assembly formed by alternately laminating these positive electrode plates and negative electrode plates while interposing an electrolyte layer between the positive electrode plates and the negative electrode plates,
One electrode plate extending step of extending and extending any one of the positive electrode plate formed in a strip shape and the negative electrode plate formed in a strip shape,
An electrolyte layer forming step of forming an electrolyte layer by applying an electrolyte solution on both plate surfaces of one of the electrode plates formed in the belt shape to form a gel electrolyte layer or disposing a solid electrolyte; and
The other electrode plate extending step of extending and extending the other electrode plate;
The strip-shaped positive electrode plate and the strip-shaped negative electrode plate are bonded together, and the bonded strip-shaped positive electrode plate, the electrolyte layer, and the strip-shaped negative electrode plate are cut at a predetermined interval to form a unit cell. Laminating step of laminating,
The other electrode plate has one plate surface opposed to the one plate surface of the one electrode plate, and is further downstream from a position downstream of the position where the electrolyte layer is formed on the one electrode plate. It is paid out toward the side,
The method for producing a multilayer membrane electrode assembly, wherein the one electrode plate and the other electrode plate are laminated in a flat plate shape. In the method for producing a multilayer membrane electrode assembly formed by alternately laminating these positive electrode plates and negative electrode plates while interposing an electrolyte layer between the positive electrode plates and the negative electrode plates,
One electrode plate extending step of extending and extending any one of the positive electrode plate formed in a strip shape and the negative electrode plate formed in a strip shape,
An electrolyte layer forming step of forming an electrolyte layer by applying an electrolyte solution on both plate surfaces of one of the electrode plates formed in the belt shape to form a gel electrolyte layer or disposing a solid electrolyte; and
The other electrode plate extending step of extending and extending the other electrode plate;
The strip-shaped positive plate and the strip-shaped negative plate are bonded together, and the bonded strip-shaped positive plate, the electrolyte layer, and the strip-shaped negative plate are wound so that the positive plate is positioned inside. A winding process,
The other electrode plate has one plate surface opposed to the one plate surface of the one electrode plate, and is further downstream from a position downstream of the position where the electrolyte layer is formed on the one electrode plate. A process for producing a multilayer membrane electrode assembly, wherein the multilayer electrode assembly is drawn out toward the side.   It has the separator arrangement | positioning process which arrange | positions the separator formed in strip | belt shape on the plate | board surface of one electrode plate formed in the said strip | belt shape, or on the plate | board surface of the other electrode plate formed in the said strip | belt shape. The manufacturing method of the multilayer membrane electrode assembly of Claim 1 or 2.   In the electrolyte layer forming step, an electrolyte solution is applied to the plate surfaces of the positive electrode plate and the negative electrode plate to form a gel electrolyte or a solid electrolyte to form an electrolyte layer, The manufacturing method of the multilayer membrane electrode assembly as described in any one of Claim 1 to 3 to do.   2. An electrolyte heating step of heating the positive electrode plate and / or the negative electrode plate by induction heating after the bonding step of bonding the belt-shaped positive electrode plate and the belt-shaped negative electrode plate. 5. A method for producing a multilayer membrane electrode assembly according to claim 4.

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