JP6394480B2 - Manufacturing method of all solid state battery - Google Patents

Description

  The present invention relates to a method for manufacturing an all-solid battery, and more specifically, suppresses insufficient injection of resin into an end portion in insert molding, and enables electrode foil deformation and foil breakage due to resin injection to be suppressed in the thickness direction of the battery. The present invention relates to a method for producing an all-solid battery capable of thinning a resin layer.

In recent years, lithium batteries have been put into practical use as batteries having high voltage and high energy density. Due to the expansion of the use of lithium batteries in a wide range of fields and the demand for high performance, various studies have been conducted to further improve the performance of lithium batteries.
Among them, since the electrolyte is not used compared to the conventional non-aqueous electrolyte lithium battery, the system required for improving the safety when using the non-aqueous electrolyte can be simplified. Therefore, it is expected that the all-solid-state battery will be put to practical use because it can have many advantages such as an increased degree of freedom and a reduced number of auxiliary devices.

However, various improvements are necessary in order to realize practical use of all solid state batteries.
As one of them, the all-solid-state battery is expected to simplify the exterior because no injection or degassing steps are required. For example, the all-solid-state battery has a structure in which the periphery of the electrode body is covered with a resin insert of the all-solid battery. There is simplification of the exterior. On the other hand, thinning the resin layer in the battery thickness direction is the most effective for improving the energy density of all-solid-state batteries, but a thin-wall insert molding technology is established by securing a flow path for resin injection. It was difficult to improve the energy density.
For this reason, various studies have been made on the insert molding technology for all solid state batteries.

For example, Patent Document 1 describes a manufacturing method of an all-solid battery in which an outer body is formed by coating with a resin. As a specific example, an all-solid battery element is sandwiched between two metal plates as electrode terminals, Although a method for producing an all-solid battery by insert molding in which resin is injected while sealing is shown, thinning of the resin layer is not shown.
Patent Document 2 describes a method of manufacturing a laminated battery in which the side surfaces of the laminated electrode laminate are inserted into a notched mold, a resin is injected into the mold, and cured to be sealed. .

Patent Document 3 discloses an all-solid battery by insert molding in which a solid battery element is loaded into a resin sealing mold, a resin composition is injected into a cavity, and the resin is cooled and sealed with an exterior material that cures the resin. The manufacturing method is shown.
Patent Document 4 describes a method for manufacturing an all-solid battery by insert molding in which a resin coating layer provided in the thickness direction of the all-solid battery element is formed into a two-layer shape including an inner resin mold and an outer insert resin. Has been.
Furthermore, Patent Document 5 describes a method for producing an all-solid battery in which resin films are arranged in advance on both surfaces in the thickness direction of an all-solid battery electrode body, and then the side surfaces of the electrode body are sealed using an insert resin. ing.

  However, by applying these known techniques, a resin coating layer is formed on the side surface of the electrode body by insert molding to suppress insufficient injection of resin into the edge, and to prevent deformation of electrode foil and breakage of the foil due to resin injection It was difficult to obtain an all-solid battery in which the resin layer in the thickness direction of the battery was thinned.

JP 2000-106154 A JP 2004-193006 A JP 2008-103288 A JP 2015-18769 A JP2015-50004A

  Therefore, the object of the present invention is to apply insert molding to an all-solid-state battery to form a resin coating layer to suppress insufficient injection of resin into the end, and to suppress electrode foil deformation and foil breakage due to resin injection. And providing an all-solid-state battery manufacturing method.

As a result of intensive studies to achieve the above object, the present inventors have applied the insert molding according to the prior art to an all-solid-state battery to form a resin coating layer. Resin does not flow easily to the part far from the injection site. On the other hand, when the injection speed is increased, the resin is partly concentrated and injected, resulting in electrode foil deformation or foil breakage, especially when the electrode body is thin. As a result of finding out that the above-mentioned phenomenon appears remarkably with a narrow foil stacking interval, and further studies, the present invention was completed.
The “distant part” means that when the injection is performed from one end portion of the electrode body, the end portion on the opposite side from the injection inlet toward the injection direction, or the electrode layer in the electrode body and the composite layer. An end portion on the side of the composite material layer is shown in a portion that is not laminated.
The present invention provides a method for producing an all-solid battery in which a resin coating layer is formed by insert molding on a side surface of an electrode body in which a plurality of electrode foils are laminated.
An injection step of injecting a resin into the side surface of the electrode body, and then a diffusion step of diffusing the injected resin between the laminated electrode foils,
Performing the injection step in a vacuum environment;
It is related with the said manufacturing method which performs the said diffusion process under atmospheric pressure after an injection | pouring process.

  In the insert molding, an all-solid battery element electrode body, which is a molded product, is mounted in advance in a mold, the mold is closed, and a resin is placed between the mold and the end surface of the electrode body (molded product). A molding method in which a molded article and a resin are integrated to form a target product is called.

  According to the present invention, insert molding is applied to an all-solid-state battery to form a resin coating layer to suppress insufficient injection into the end portion of the resin and to enable suppression of electrode foil deformation and foil breakage due to resin injection. .

FIG. 1 is a partially enlarged sectional view of an electrode body to which a manufacturing method according to an embodiment of the present invention is applied. FIG. 2 is a front view and an oblique right side schematic view of an electrode body to which the manufacturing method of the embodiment of the present invention is applied. FIG. 3 is a schematic diagram showing a part of the steps for explaining the method for producing the all solid state battery of the embodiment of the present invention. FIG. 4 is a schematic diagram for explaining the steps of the manufacturing method of the all-solid battery according to the prior art. FIG. 5 is a copy of a photograph of a sample of an all solid state battery produced by the prior art. FIG. 6 is a schematic view for explaining a method for producing an all-solid battery according to another embodiment of the present invention. FIG. 7 is a schematic diagram for explaining an injection step in the steps of the method for producing an all solid state battery according to another embodiment of the present invention. FIG. 8 is a schematic diagram for explaining the steps of the method for producing an all solid state battery according to still another embodiment of the present invention. FIG. 9 is a schematic view of a production apparatus that can be used in the method for producing an all solid state battery according to an embodiment of the present invention. FIG. 10 is a partially enlarged cross-sectional view of the electrode body after encapsulating the resin by applying the method for manufacturing an all solid state battery of the embodiment of the present invention. FIG. 11 is a partial enlarged cross-sectional view of an electrode body after enclosing a resin by applying the conventional technique.

In particular, in the present invention, the following embodiments can be mentioned.
1) Before the injection step, arrange a resin flow confirmation member at the end of the electrode body,
The manufacturing method, wherein the injecting step is performed by injecting resin until the resin reaches the resin flow confirmation member.
2) Furthermore, it has a resin flow confirmation step after the diffusion step,
The resin flow confirmation step is performed by confirming the resin flow position with a heat monitoring device (sometimes called a thermoviewer),
The said manufacturing method which repeats from an injection | pouring process again when resin flow is insufficient.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
As an electrode body in an embodiment of the present invention, a negative electrode foil, a negative electrode mixture layer containing a negative electrode active material and a solid electrolyte, a solid electrolyte layer, a positive electrode foil, and a positive electrode mixture containing a positive electrode active material and a solid electrolyte There are no limitations as long as the electrode body is formed by laminating a plurality of thin electrode foils having layers. For example, as shown in FIG. 1, as the electrode body 1, both surfaces of a solid electrolyte layer 2 and a negative electrode foil 3 are sequentially formed. A negative electrode mixture layer 4 containing a negative electrode active material and a solid electrolyte, a solid electrolyte layer 2, a positive electrode mixture layer 6 containing a positive electrode active material and a solid electrolyte on both sides of the positive electrode foil 5, a solid electrolyte layer 2, and a negative electrode A negative electrode mixture layer 4 including a negative electrode active material and a solid electrolyte on both surfaces of the foil 3, a solid electrolyte layer 2, a positive electrode mixture layer 6 including a positive electrode active material and a solid electrolyte on both surfaces of the positive electrode foil 5, and a solid electrolyte layer 2. A negative electrode active material and a solid electrolyte are included on both surfaces of the negative electrode foil 3. Negative-electrode mixture layer 4, and a thin plurality of electrode foil comprising a solid electrolyte layer 2 can be cited is an electrode laminated in layers. The electrode body can have any length, width and thickness, for example, as shown in FIG. 2, the length (20-100 mm, typically 74 mm), width (1-10 mm, The thickness (less than 1 mm, typically 0.1 mm) is smaller than (typically 2 mm).

According to the method for producing an all solid state battery of an embodiment of the present invention, in the method for producing an all solid state battery, a resin coating layer is formed by insert molding on the side surface of an electrode body in which a plurality of electrode foils are laminated.
An injection step of injecting a resin into the side surface of the electrode body, and then a diffusion step of diffusing the injected resin between the laminated electrode foils,
Performing the injection step in a vacuum environment;
The diffusion process is performed under atmospheric pressure after the injection process. By the manufacturing method, the suppression of insufficient injection of the resin between the laminated electrode foils, particularly the electrode body end portion, and the deformation of the electrode foil and the foil breakage are compatible. Is possible.
Theoretically elucidating that the method of manufacturing an all-solid-state battery according to an embodiment of the present invention can achieve both suppression of insufficient resin injection into the end portion of the electrode body and suppression of electrode foil deformation and foil breakage. However, the injection process for injecting the resin is performed in a vacuum environment, and then the diffusion process is performed under atmospheric pressure, so that the resin is injected from the four directions of the electrode body, and as shown in FIG. It is considered that the resin can enter between the electrode foils by capillarity due to being released to atmospheric pressure in the diffusion process.

  On the other hand, when the electrode body is resin-coated by insert molding according to the prior art, as shown in FIG. 4, when the coating resin layer is thin, a molten resin (or resin solution) is used with a narrow gap as a resin flow path. Need to flow. For this reason, when the resin injection speed is reduced, many injection omissions (insufficient injection) occur at the end of the electrode body, for example, at the corners. When the resin injection speed is increased to avoid injection omission, as shown in FIG. Electrode foil deformation and foil breakage due to resin injection concentration can occur.

The method for producing an all-solid battery according to another embodiment of the present invention is a method for producing an all-solid battery in which a resin coating layer is formed by insert molding on the side surface of an electrode body in which a plurality of electrode foils are laminated.
An injection step of injecting a resin into the side surface of the electrode body, and then a diffusion step of diffusing the injected resin between the laminated electrode foils,
Performing the injection step in a vacuum environment;
Perform the diffusion step under atmospheric pressure after the injection step,
Prior to the injection step, as shown in FIG. 6, a resin flow confirmation member is disposed at the end of the electrode body, and the injection step is performed by injecting resin until the resin reaches the resin flow confirmation member.

As the resin flow confirmation member, a heat-resistant base material, for example, a heat-resistant resin, for example, a structure that can be inserted into an end portion (for example, a corner) of an electrode body made of Teflon (registered trademark), for example, a rectangular strip in two directions has a right angle. In addition, a molded body made of a thin resin strip in three directions having a grip portion in the other direction can be mentioned. The resin flow confirmation member may be inserted between the electrode foils as shown in FIG.
According to the above-described embodiment, as shown in FIG. 7, the resin body can be confirmed to be injected and diffused to the corners by the seepage after the resin has reached the corners of the electrode body. It is possible to confirm the diffusion to the part, and it is preferable because an all-solid battery in which a resin coating layer having a stable quality is formed can be obtained.

In particular, in still another embodiment of the present invention, as shown in FIG. 8, the method for producing an all-solid battery is a method for forming a resin coating layer by insert molding on the side surface of an electrode body in which a plurality of electrode foils are laminated. In the method for producing a solid battery,
An injection step of injecting a resin into the side surface of the electrode body, and then a diffusion step of diffusing the injected resin between the laminated electrode foils,
Performing the injection step in a vacuum environment;
The diffusion step is performed under atmospheric pressure after the injection step,
Furthermore, as shown in FIG. 8, it has a resin flow confirmation step after the diffusion step, and the resin flow confirmation step is performed by confirming the flow position of the resin with a thermoviewer. Repeat from the injection step again.

  According to the above-described embodiment, heat monitoring is performed from above the electrode body by a thermoviewer, and when the resin flow is insufficient, the process proceeds to the injection process again, and then proceeds to the diffusion process for diffusing the injected resin. Since the diffusion of the resin to the corner can be confirmed, it is possible to confirm the diffusion to the corner of the electrode body in a non-destructive manner, and it is possible to obtain an all-solid-state battery in which a resin coating layer having a stable quality is obtained. It is.

As the resin to be injected into the side surface of the electrode body in the embodiment of the present invention, a thermoplastic resin such as polypropylene, polyethylene, polyamide or the like, or a thermosetting resin such as epoxy resin, phenol resin or unsaturated polyester resin is preferably used. Is a thermoplastic resin.
As the resin to be injected, polypropylene is desirable from the viewpoint of molding temperature and battery durability.
Said resin, preferably a thermoplastic resin, for example polypropylene, can contain additives or fillers known per se.

  The electrode body of the all solid state battery can be obtained as follows. For example, a positive electrode slurry containing a positive electrode active material, a solid electrolyte such as a sulfide solid electrolyte material, a binder and a solvent is applied to both surfaces of the positive electrode foil to obtain a positive electrode. On the other hand, a negative electrode slurry containing a negative electrode active material, a solid electrolyte, a binder and a solvent is applied to both surfaces of a negative electrode foil to obtain a negative electrode. A plurality of the positive electrodes and the negative electrodes can be stacked via a solid electrolyte to obtain an electrode body. The lamination can be performed by pressing at the final pressing pressure, for example, by cold isostatic pressing (CIP).

A metal foil such as an Al (aluminum) foil can be used as the positive electrode foil, and a metal foil such as a Cu foil can be used as the negative electrode foil.
Each of the positive electrode foil and the negative electrode foil has a thickness of 0.1 to 10 μm, more preferably 0.5 to 5 μm.

As the positive electrode active material, a material into which Li can be inserted, for example, Li (Ni _a Co _b Al _1-ab ) O ₂ [a, b is an arbitrary number less than 1. _{However, a + b ≦ 1],} Li (Ni a Co b Mn 2-a-b) O 4 [a, b is any number less than 2. However, for example, LiNi _1/2 Mn _1/2 O ₂ , LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , LiNi _3/5 Co _1/5 Mn _1/5 O ₂ , etc. LiMn ₂ O ₄ , LiNi _1/2 Mn _3/2 O ₄ , LiNiPO ₄ , LiMnPO ₄ , Li ₃ Fe ₂ (PO ₄ ) ₃ , Li ₃ V ₂ (PO ₄ ) _3, etc., preferably LiCoO ₂ LiNi _1/3 Co _1/3 Mn _1/3 O ₂ can be mentioned. The solid electrolyte contained in the positive electrode mixture layer is an arbitrary sulfide solid electrolyte, for example, Li ₂ S: P ₂ S ₅ = 50: 50 to 100: 0 (mass ratio) and Li ₂ S and A sulfide solid electrolyte obtained by mechanical milling P ₂ S ₅ can be used.
Further, the positive electrode mixture layer may contain a binder, for example, a fluorine-containing resin such as polyvinylidene fluoride, SBR or a conductive auxiliary agent such as carbon such as acetylene black or ketjen black.
The thickness of the positive electrode mixture layer may be in the range of 100 nm to 20 μm in total, for example, 0.5 to 5 μm, in one positive electrode.

As the negative electrode active material, a material into which Li can be inserted, for example, a known carbon-based negative electrode mixture such as graphite, preferably amorphous carbon, for example, hard carbon can be used.
The solid electrolyte contained in the negative electrode mixture layer may be a sulfide solid electrolyte that can be applied to the positive electrode mixture layer.
Further, the negative electrode mixture layer can contain a binder for binding, for example, a fluorine-containing resin such as polyvinylidene fluoride, SBR and a conductive auxiliary agent such as carbon such as acetylene black and ketjen black.
The thickness of the negative electrode mixture layer may be in the range of 100 nm to 20 μm in total, for example, 0.5 to 5 μm, in one negative electrode.

Examples of the solid electrolyte include sulfide-based solid electrolytes and oxide-based solid electrolytes. Suitably, sulfide-based solid electrolytes such as Li ₂ S—SiS ₂ , LiI-Li ₂ S— SiS ₂ , liI-li ₂ S—P ₂ S ₅ , LiI—Li ₂ S—B ₂ S ₃ , Li ₃ PS ₄ , Li ₂ S—P ₂ S ₅ , among them Li ₂ S: P ₂ S ₅ = 50:50 to 100: 0 (mass ratio) Li ₂ S and P ₂ S ₅ are mixed and mechanically milled to obtain a sulfide solid electrolyte, such as Li ₂ S—P ₂ S ₅ , 70Li ₂ S-30P ₂ S ₅ , 80Li ₂ S-20P ₂ S ₅ , Li ₂ S—SiS ₂ , LiGe _0.25 P _0.75 S _4, etc. , 75Li It can be mentioned _S-25P 2 S ₅ sulfide glass.
The thickness of the solid electrolyte layer is preferably 0.1 to 5 μm, more preferably 1 to 2 μm.

  In the electrode body in the embodiment of the present invention, as shown in FIG. 1, the capacity ratio of the positive electrode mixture layer and the negative electrode mixture layer (positive electrode mixture layer / negative electrode mixture layer) is 1 or less, for example, It is suitably 0.9 or less and 0.5 or more.

  By the method for producing an all solid state battery of the embodiment of the present invention, an all solid state battery in which insufficient injection into the end portion of resin in insert molding is suppressed and electrode foil deformation and foil breakage due to resin injection are suppressed can be obtained. .

Examples of the present invention will be described below.
The following examples are for illustrative purposes only and are not intended to limit the invention.

Example 1
The electrode body 1 is arranged in the manufacturing apparatus 10 having the vacuum chamber 11 shown in FIG.
After exhausting the air in the apparatus from the air outlet 12 to create a vacuum environment, a resin is injected into the side surface of the electrode body 1 from the resin dispenser 13,
Next, air is introduced from the air inlet 14 to diffuse the resin at atmospheric pressure in the apparatus,
The flow position of the resin is confirmed by the thermoviewer 15, and if it is confirmed that the resin has reached the corner of the electrode body, the all solid battery having the resin coating layer is taken out, and the resin reaches the corner of the electrode body. If the resin flow is confirmed to be insufficient, the air in the apparatus is discharged from the air discharge port 12 to form a vacuum environment, and then the injection process is repeated again to form an all solid having the resin coating layer formed thereon. A battery can be made.
FIG. 10 shows a partially enlarged cross-sectional view of the electrode body after encapsulating the resin by the above method.
From FIG. 10, according to the sail manufacturing method of Example 1, the resin enters and is injected to the end portion (base portion) on the side of the mixture layer in the portion of the electrode foil in the electrode body that is not laminated with the mixture layer. It has been confirmed.

Comparative Example 1
FIG. 11 shows a partially enlarged cross-sectional view of the electrode body after applying the conventional method and encapsulating the resin.
From FIG. 11, according to the conventional method, it was confirmed that the resin was not contained up to the portion of the electrode body that was not laminated with the composite layer of the electrode foil.

  According to the present invention, insert molding is applied to an all-solid-state battery to form a resin coating layer to suppress insufficient injection of resin into the end, and to suppress electrode foil deformation and foil breakage due to resin injection. An all-solid battery having a thin resin layer in the thickness direction can be easily obtained.

DESCRIPTION OF SYMBOLS 1 Electrode body in embodiment of this invention 2 Solid electrolyte layer 3 Negative electrode foil 4 Negative electrode compound material layer 5 Positive electrode electrode foil 6 Positive electrode compound material layer 10 Manufacturing apparatus 11 Vacuum chamber 12 Air exhaust port 13 Resin dispenser 14 Air inlet 15 Thermo viewer

Claims (1)

In the method for producing an all-solid battery in which a resin coating layer is formed by insert molding on the side surface of an electrode body in which a plurality of electrode foils are laminated,
Injected in a vacuum environment with a resin side of the electrode body, injection step, then
After implantation process, is diffused at atmospheric pressure the injected the resin between laminated electrode foil, a diffusion process,
Have, and
Before the injection step, a resin flow confirmation member is disposed at an end of the electrode body, and the injection step is performed by injecting the resin until the resin reaches the resin flow confirmation member. Or
After the diffusion step, there is a resin flow confirmation step in which the flow position of the resin is confirmed by a heat monitoring device, and when the resin flow is insufficient, it is repeated from the injection step again.
A method for producing an all-solid battery.

Images