JP5836542B2 - A method for producing a lithium ion secondary battery. - Google Patents

Description

The present invention relates to a lithium ion secondary battery and a method for producing a lithium ion secondary battery.
This application claims priority based on Japanese Patent Application No. 2013-227478 for which it applied to Japan on October 31, 2013, and uses the content here.

  In general, a lithium ion secondary battery is formed by laminating an electrode plate constituting a positive electrode and an electrode plate constituting a negative electrode with a solid, semi-solid or liquid electrolyte interposed therebetween, and projecting a terminal tab, It is housed in an exterior material and sealed. And the sealing of the laminated body with the exterior material is performed in a state where the tip of the terminal tab protrudes from the exterior material (for example, Patent Document 1).

JP2013-8691A

By the way, in the conventional lithium ion secondary battery, since an internal space that is a gap between the laminate and the sealing portion of the exterior material is formed, it is formed between the laminate and the sealing portion of the exterior material. The relative dimension of the sealing part or laminated body which seals the inside of the exterior material is reduced by the amount of the gap. However, in order to reliably prevent leakage of the electrolytic solution from the exterior material, it is necessary to set a large area ratio of the sealing portion in the exterior material without changing the size of the laminate.
Then, in view of the said subject, this invention makes it a subject to provide the manufacturing method of the lithium ion secondary battery and the lithium ion secondary battery by which the area ratio of the sealing part in an exterior material was set large.

The present invention provides a laminate in which electrode plates having terminal tabs and semi-solid or solid electrolyte layers are alternately laminated, and the laminate is accommodated therein, and a part of the terminal tab is protruded and sealed. A sheet-like exterior material that is provided, and the exterior material is provided with a laminate adjacent sealing portion that seals the laminate adjacent to at least a part of an edge of the laminate. Features.
According to this structure, the area of the sealing part which seals a laminated body in at least one part of the said edge can be enlarged effectively.

The present invention is characterized in that the laminated body adjacent sealing portion is provided adjacent to the end edge over the entire circumference of the edge of the laminated body.
According to this structure, the area of the sealing part which seals a laminated body over the perimeter of the edge of the said laminated body can be enlarged effectively.

The present invention is characterized in that the laminated body adjacent sealing portion is provided over the entire region other than the region where the laminated body is disposed in the exterior material.
According to this structure, the area of a sealing part can be enlarged most effectively.

The method for producing a lithium ion secondary battery of the present invention includes a laminate forming step of forming a laminate in which electrode plates having terminal tabs and semi-solid or solid electrolyte layers are alternately laminated, and the laminate A sealing step of sandwiching the outer packaging material, projecting a part of the terminal tab to the outer packaging material, and sealing the laminated body adjacent to the edge over the entire circumference of the edge of the laminated body It is characterized by having.
According to this configuration, since it is only necessary to laminate and fuse the entire exterior material including the area where the laminated body is disposed and the area necessary for sealing the laminated body at the same time, the sealing of the lithium ion secondary battery is made stronger. By doing so, quality stability and cycle characteristics are improved.

In the sealing step, the present invention sandwiches a slip sheet that forms a deaeration space adjacent to a part of the edge of the laminate, and the outer periphery of the laminate and the entire periphery of the edge of the slip sheet. The step of sealing the laminated body and the interleaf paper adjacent to the edge is defined as a first sealing step, and after the first sealing step and the first sealing step, A second sealing step for taking out paper and final sealing is provided.
According to this configuration, it is possible to remove gas that may be generated during the initial charging of the lithium ion secondary battery.

The present invention is characterized in that the first sealing step is performed using a vacuum laminator, a roller, or a vacuum packaging machine.
According to this configuration, the lithium ion secondary battery can be manufactured efficiently.

  Advantageous Effects of Invention According to the present invention, there is an effect that it is possible to provide a lithium ion secondary battery and a method for manufacturing a lithium ion secondary battery that can effectively set the area of the sealing portion of the exterior material.

1 is a plan view of a lithium ion secondary battery shown as a first embodiment of the present invention. It is a top view which shows the positive electrode plate of the lithium ion secondary battery shown as the 1st embodiment of this invention. It is a top view which shows the negative electrode plate of the lithium ion secondary battery shown as the 1st embodiment of this invention. It is sectional drawing which showed typically the state which looked at the lithium ion secondary battery of FIG. 1 by the Y1-Y2 line. It is a top view which shows the laminated body of the lithium ion secondary battery shown as the 1st embodiment of this invention. It is a top view which shows a part of manufacturing process of the lithium ion secondary battery shown as the 1st embodiment of this invention. It is a top view which shows the lithium ion secondary battery shown as a 1st embodiment of this invention.

  Hereinafter, the lithium ion secondary battery and the method for producing the lithium ion secondary battery of the present invention will be described with reference to the drawings.

FIG. 1 is a plan view showing a schematic configuration of a lithium ion secondary battery 1 manufactured by the manufacturing method of one embodiment of the present invention.
As shown in this figure, a lithium ion secondary battery 1 that is an object of the manufacturing method according to an embodiment of the present invention is a solid or gel electrolyte layer (not shown in the figure) coated with an electrolyte. Alternately, a positive electrode plate (electrode plate) 2 on which is formed and a negative electrode plate (electrode plate) 3 on which a solid or gel electrolyte layer (not shown in the figure) is formed by applying an electrolyte The terminal tabs 4 are protruded from the end 7 of the positive electrode plate 2 and the terminal tabs 5 are protruded from the end 11 of the negative electrode plate 3.
The solid or gel electrolyte layer may be formed on either one of the positive electrode plate 2 or the negative electrode plate 3, and the positive electrode plate 2, the electrolyte layer, and the negative electrode plate 3 may be alternately stacked. .

As shown in FIG. 2, the positive electrode plate 2 uses a current collector 6 made of an aluminum foil in which an end 7 serving as a joining region with the terminal tab 4 is formed at one end of a substantially rectangular shape. 6, the positive electrode active material layer 8 is formed on both surfaces with the end 7 being left.
The positive electrode active material layer 8 is obtained by, for example, preparing a positive electrode slurry in which a positive electrode active material, a conductive auxiliary agent, and a binder serving as a binder are dispersed in a solvent, on a current collector and drying. is there.

As the positive electrode active material, for example, a lithium metal acid 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) can be used. Specifically, lithium cobaltate, lithium nickelate, lithium manganate, lithium iron phosphate, or the like can be used as the metal acid lithium compound.
Acetylene black or the like is used as the conductive assistant, and polyvinylidene fluoride or the like can be used as the binder.

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

  Moreover, as shown in FIG. 3, the negative electrode plate 3 uses the collector 10 which consists of copper (Cu) by which the edge part 11 used as the area | region for joining with the terminal tab 5 was formed in the substantially rectangular end, for example. The negative electrode active material layer 12 is formed on both surfaces of the current collector 10 with the end 11 remaining.

The negative electrode active material layer 12 is prepared by, for example, preparing a negative electrode slurry in which a negative electrode active material, a binder serving as a binder, and a conductive additive added as necessary are dispersed in a solvent on a current collector, It can be obtained by drying.
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 can be used.
For example, polyvinylidene fluoride or the like can be used as the binder, and acetylene black or the like can be used as the conductive auxiliary agent.
The terminal tab 5 of the negative electrode plate 3 is provided so as to be joined to the end portion 11 and project outward, and can be formed of nickel or the like, for example.

The electrolyte layer 13 shown in FIG. 4 is obtained by gelling or solidifying a liquid electrolyte applied to both plate surfaces of the positive electrode plate 2 and the negative electrode plate 3. The electrolyte layer 13 may be coated on one side of each of the positive electrode plate 2 and the negative electrode plate 3, but is preferably provided on both sides.
The solid or gel electrolyte layer may be formed on either one of the positive electrode plate 2 or the negative electrode plate 3, and the positive electrode plate 2, the electrolyte layer, and the negative electrode plate 3 may be alternately stacked. .

  A known electrolyte can be used for the electrolyte layer. For example, a polymer matrix and a non-aqueous electrolyte solution (that is, a non-aqueous solvent and an electrolyte salt) that are gelled to cause stickiness on the surface, or a polymer matrix and a non-aqueous solvent that are made of a solid electrolyte and Can be formed. Further, the electrolyte layer may have a structure in which the electrolyte is supported on the porous body. Whichever electrolyte layer is used, those having adhesiveness when the electrolyte is applied to the positive electrode plate 2 or the negative electrode plate 3 are preferable. The electrolyte layer preferably forms a free-standing film that does not separate from the plate surface of the positive electrode plate 2 or the negative electrode plate 3.

  Polymer matrices include polyvinylidene fluoride (PVDF), hexafluoropropylene copolymer (PVDF-HFP), polyacrylonitrile, polyalkylene ether (polyethylene oxide, polypropylene oxide, etc.), polyester, polyamine, polyphosphazene, Polysiloxane or the like can be 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; It can be prepared by mixing an ether compound such as tetrahydrofuran or dimethoxyethane; a nitrile compound such as acetonitrile; a sulfone compound such as sulfolane; an amide compound such as dimethylformamide;

Moreover, when making electrolyte solution into a solid electrolyte, nitrile compounds, such as acetonitrile; Ether compounds, such as tetrahydrofuran: Amide type compounds, such as a dimethylformamide, can be prepared individually or in mixture of 2 or more types.
The electrolyte salt is not particularly limited, and lithium salts such as lithium hexafluorophosphate, lithium perchlorate, and lithium tetrafluoroborate can be used.

  Under the above configuration, the negative electrode plate 3, the solid or semi-solid electrolyte layer 13, and the positive electrode plate 2 are laminated in this order, and as shown in FIG. 5, the terminal tabs 4 and 5 are projected to form a laminated body 15. doing.

As the exterior material 16 shown in FIG. 4, a flexible laminate film (such as an aluminum laminate film that is a composite material of an aluminum foil and a resin film), a SUS sheet, a water vapor barrier film, or the like is preferably used.
As shown in FIGS. 1 and 4, the exterior material 16 is formed in a size that can enclose and seal the laminate 15. And the exterior | packing material 16 contains the area | region which adjoins so that a clearance gap may not be formed as much as possible between the edge 15a of the laminated body 15 along the edge 15a, 15a ... of the laminated body 15. Substantially the entire region other than the region where the body 15 is disposed (that is, the region in which the sheet-like exterior materials 16 and 16 disposed opposite to each other can directly contact each other) is used as the sealing portion P.

Here, the adjacent region so as not to form a gap as much as possible means that the laminate 15 is sandwiched by a gap that can be physically generated when heated and pressed to the edge 15a of the laminate 15 to the middle. It means a region surrounding the end edge 15a. Specifically, the “physical gap that can be generated” as used in the present embodiment is, for example, 2 mm around the edge 15a of the laminate 15 when heated and pressurized by a vacuum laminator, roller, or vacuum packaging machine. Or less, preferably within 1.3 mm, more preferably within 0.8 mm.
In addition, it is preferable that the separator (not shown) is interposed. A nonwoven fabric or the like is used for the separator.

Next, the manufacturing method of the lithium ion secondary battery 1 which concerns on one Embodiment of this invention is demonstrated using FIGS. The manufacturing method of the lithium ion secondary battery 1 includes the following steps.
(1) Laminate forming step of alternately laminating electrode plates (positive electrode plate 2, negative electrode plate 3) having terminal tabs 4 and 5 and semi-solid or solid electrolyte layer 13 to form laminate 15;
(2) The laminate 15 and the interleaving paper 17 forming the deaeration space are sandwiched between the exterior materials 16, and part of the terminal tabs 4, 5 are projected from the exterior material 16, and the edges of the laminate 15 15a and the first sealing step of sealing adjacent to this edge over the entire circumference of the edge of the interleaf 17 (excluding the adjacent portion of the laminate 15 and interleaf 17), and (3) A second sealing step in which the interleaf paper 17 is taken out and finally sealed after the sealing step.

<Laminated body 15 formation process>
In the laminated body forming step, as shown in FIG. 4, the negative electrode plate 3 and the positive electrode plate 2 are laminated with a semi-solid or solid electrolyte layer 13 interposed therebetween to form a laminated body 15. At this time, the terminal tabs 4 and 5 protruded from each positive electrode plate 2 and each negative electrode plate 3 are bundled and welded, and the direction is not particularly limited, but in this embodiment, the terminal tabs 4 and 5 are directed in the same direction. Protruding. The electrode plates located in the uppermost layer and the lowermost layer of the laminate 15 are preferably the negative electrode plate 3.

<First sealing step>
In the first sealing step, as shown in FIG. 6, the laminated body 15 and the interleaf paper 17 forming the deaeration space are adjacent to each other and sandwiched between the exterior materials 16, 16, and the terminal tabs 4, 5 are disposed in the exterior material 16. The exterior material 16 is sealed adjacent to the end edge 15a over the entire periphery of the end edge 15a of the laminated body 15 in a state of protruding from the edge. Here, the “degassing space” means a space provided for extracting gas generated during initial charging described later. A slight gap may be formed between the laminate 15 and the interleaf paper 17 as long as the gap between them is not sealed. Moreover, although it is not essential, it is preferable that the terminal tabs 4 and 5 are being fixed to the exterior | packing material 16 with the sealing films 20 and 20 formed, for example with the polypropylene, respectively.

  At this time, the sealing portion is used by using a vacuum laminator, a roller, or a vacuum packaging machine so that the entire region of the exterior material 16 other than the laminated body 15 and the interleaf paper 17 is fused and becomes the sealing portion P. The region to be P is fused by heating and pressing almost simultaneously. At this time, it is preferable that sealing is performed while pressurizing between the exterior parts 16 and 16 in a state where the electrolyte layer constituting the laminated body 15 is softened. Thereby, since the unevenness | corrugation of the electrolyte layer which arises in the interface part with an electrode is planarized more, the clearance gap between a laminated body and an exterior material can be reduced. By being manufactured in this manner, uniform charge / discharge can be performed. In addition, the cycle characteristics can be improved. When pressurizing between the exterior parts 16, 16, it is preferable to apply uniform pressure over the entire surface of the laminate 15, and it is more preferable to apply pressure using a smooth plate. The method of heating so that the electrolyte layer is softened is not particularly limited, and examples thereof include a method of heating the laminate 15 in advance or heating a laminate plate or a roller of a vacuum laminator.

  Specifically, in the case of using a vacuum laminator, for example, two rubber plates having an area larger than the area of the outer packaging material 16 to be placed are arranged so as to be opposed to each other, and the rubber plates are placed between these rubber plates. The packaging materials 16 and 16 on which the laminated body 15 is arranged are sandwiched. Then, compressed air is fed into one rubber plate to expand it, and the rubber plate is heated to, for example, 100 ° C. to 200 ° C., and the exterior materials 16, 16 sandwiched between the rubber plates are heated and pressurized, It heats simultaneously, deaerating between 16 and making it vacuum. Sealing is completed by sealing this entire state where the exterior materials 16 and 16 other than the laminated body 15 are in contact with each other for several tens of seconds and forming the sealing portion P.

When using rollers, for example, a plurality of rollers having a predetermined diameter (for example, 3 cm) are arranged in parallel in the vertical direction with a predetermined interval and heated. The predetermined interval is set to the same dimension as the thickness dimension desired for the lithium ion secondary battery 1.
The exterior material 16, 16 having the laminate 15 sandwiched between these rollers is passed, the air between the exterior materials 16, 16 is pushed out by the roller to deaerate, and the laminate 15 is arranged by heating and pressurizing. Sealing is completed by sealing the entire region where the outer packaging materials 16, 16 other than the above-mentioned portions are in contact with each other and forming the sealing portion P.

In the second sealing step, initial charging is performed in a state where the exterior material 16 is sealed in the first sealing step, and the gas generated during the initial charging is removed. In the degassing, after completion of the initial charging, the sealing of the outer packaging material 16 is partially cut in a vacuum environment, the outer packaging material 16 is opened, the interleaf paper 17 is taken out, and the region where the interleaf paper 17 is disposed is laminated again. It is performed by fusing and final sealing.
At this time, it is preferable that sealing is performed while pressurizing between the exterior parts 16 and 16 in a state where the electrolyte layer constituting the laminated body 15 is softened. Thereby, since the unevenness | corrugation of the electrolyte layer which arises in the interface part with an electrode is planarized more, the clearance gap between a laminated body and an exterior material can be reduced. By being manufactured in this manner, uniform charge / discharge can be performed. Further, cycle characteristics can be improved. When pressurizing between the exterior parts 16, 16, it is preferable to apply uniform pressure over the entire surface of the laminate 15, and it is more preferable to apply pressure using a smooth flat plate. The method of heating so that the electrolyte layer is softened is not particularly limited, and examples thereof include a method of heating the laminate 15 in advance or heating a laminate plate or a roller of a vacuum laminator.
In addition, you may perform the process of pressurizing between the exterior parts 16 and 16 in any one or both of a 1st, 2nd sealing process, when an electrolyte layer is a softened state. The pressurizing step is preferably performed only in the second sealing step. The effect that the gas generated during the initial charging in the second sealing step is less likely to stay between the laminates by not flattening the unevenness of the electrolyte layer generated at the interface with the electrode in the first sealing step. Can be expected.
Through the above steps, the lithium ion secondary battery 1 shown in FIG. 1 or FIG. 7 is completed.

  According to the lithium ion secondary battery of the present invention, the laminate 15 is sealed by the exterior material 16 along the edge 15a of the laminate 15 without substantially forming a gap with the edge 15a. Therefore, it is possible to make the sealing part P of the exterior material 16 larger while ensuring the maximum space in which the laminate 15 can be accommodated in the exterior material 16. That is, by forming the sealing portion P as large as possible without relatively reducing the surface area of the laminate 15 encapsulated in the exterior material 16, lithium ion that is highly reliable in terms of airtightness. The effect that it can be set as the secondary battery 1 is acquired.

In addition, since the sealing portion P of the exterior material 16 is maximally secured according to the shape of the laminate 15, it is possible to prevent the laminated state of the laminate 15 from being misaligned inside the exterior material 16. The effect that it can be obtained.
Moreover, since the laminated body 15 is sealed in a state in which the laminate 15 is fitted in the exterior material 16, an effect of preventing use of a useless electrolyte and suppressing material cost can be obtained.

  Conventionally, in order to prevent leakage of the electrolytic solution, a method is employed in which the laminate 15 is put in a bag shape by welding three sides of the exterior material, and then the electrolyte is injected to perform final sealing. Therefore, it takes time and cost to manufacture the lithium ion secondary battery. However, according to the method for manufacturing a lithium ion secondary battery of the present invention, the sealing portion P surrounding the laminated body 15 with the solid or gel electrolyte layer interposed is removed by a vacuum laminator, a roller, a vacuum packaging machine, or the like. Since it can seal simultaneously, the effect that a 1st sealing process can be performed very efficiently is acquired.

  In addition, in the said embodiment, although it becomes the structure by which all area | regions other than the area | region where the laminated body 15 was distribute | arranged were used as the sealing part P, this invention is the edge 15a of the laminated body 15 in the sealing part P. As long as it is provided as close as possible with a sufficient width dimension (sealing dimension), a part other than the region where the laminated body 15 is disposed is not the sealing portion P. It does not prevent it.

  Further, in the above embodiment, the first sealing step in which the interleaf paper 17 is disposed and the laminated body 15 is sealed, and after the gas is released, the interleaf paper 17 is taken out and the second sealing is performed. However, the present invention may be a sealing step in which the laminated body 15 is finally sealed without providing the interleaf paper 17.

  Further, in the above embodiment, a cover is provided at the time of heating and pressurizing so that the electrode is not easily heated, or the shape of the heater is deformed so as to be heated only at the sealing portion. Also good.

Moreover, in the said embodiment, although the positive electrode plate 2 and the negative electrode plate 3 are formed in the substantially rectangular shape, and the laminated body 15 becomes a rectangle by planar view, the shape of the laminated body 15 of this invention is a rectangle. It is not limited to this, and it can be freely set to a circular, polygonal or other desired shape.
The method for manufacturing a lithium ion secondary battery according to the present invention uses the vacuum laminator or the like to cover the entire surface of the exterior materials 16 and 16 even when the outer shape of the laminate 15 is circular, polygonal, or other complicated shapes. The sealing part P can be formed so as to be adjacent to the edge 15a of the laminated body 15 by heating and pressurizing substantially simultaneously. And the effect that the effect similar to above-mentioned embodiment can be exhibited is acquired.

1 Lithium ion secondary battery 2 Positive electrode plate (electrode plate)
3 Negative electrode plate (electrode plate)
13 Solid or Gel Electrolyte Layer 15 Laminate 15a Edge 16 Exterior Material 17 Interleaf P Sealing Part

Claims (2)

A laminate forming step of forming a laminate in which electrode plates having terminal tabs and semi-solid or solid electrolyte layers are alternately laminated, and sandwiching the laminate in an exterior material, and the exterior material includes a terminal tab A sealing step of projecting a part and sealing the laminated body adjacent to the edge over the entire circumference of the edge of the laminated body;
In the sealing step, a slip sheet that forms a deaeration space adjacent to a part of the edge of the laminate is sandwiched, and the exterior material covers the entire periphery of the laminate and the edge of the slip sheet. The step of sealing the laminate and the interleaf paper adjacent to the edge is defined as a first sealing step, and the initial charging is performed after the first sealing step and the first sealing step. A process of performing;
A method of manufacturing a lithium ion secondary battery, comprising: a second sealing step of cutting a part of the exterior material, taking out the interleaf, and finally sealing. The method for producing a lithium ion secondary battery according to claim 1 , wherein the first sealing step is performed using a vacuum laminator, a roller, or a vacuum packaging machine.

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