JP6919606B2 - Manufacturing method of electrode sheet for sulfide all-solid-state battery - Google Patents

Description

The present invention relates to a method for producing an electrode sheet used in a sulfide all-solid-state battery.

Patent Document 1 describes, as an electrode sheet used for a sulfide all-solid-state battery, a current collecting foil made of copper foil, a conductive resin layer formed on the surface of the current collecting foil, and a surface of the conductive resin layer. A negative electrode sheet having an electrode mixture layer formed above is disclosed. It is described that a sulfide solid electrolyte is added to the electrode mixture constituting the electrode mixture layer in addition to the electrode active material and the binder.

Japanese Unexamined Patent Publication No. 2014-093156

By the way, the above-mentioned electrode sheet is manufactured as follows, for example. Specifically, a slurry in which conductive particles and molten resin are mixed is applied onto the surface of a current collector foil made of copper foil and cooled to have a conductive resin layer on the surface of the current collector foil. A current collector foil with a conductive resin layer is produced. After that, the electrode active material, the binder, the sulfide solid electrolyte, and the solvent are mixed to prepare an electrode mixture in a slurry state (referred to as an electrode mixture slurry), and the electrode mixture slurry is die-coated. The electrode sheet (negative electrode sheet) is produced by applying the current collecting foil with the conductive resin layer on the surface of the conductive resin layer.

However, since the electrode mixture slurry has fluidity, when the electrode mixture slurry is applied onto the surface of the conductive resin layer of the current collecting foil with the conductive resin layer, the electrode mixture slurry is applied. However, there was a risk that it would permeate into the inside of the conductive resin layer (soak into it) and come into contact with the current collecting foil made of copper foil. Since the electrode mixture slurry contains a sulfide solid electrolyte, the sulfur component (S) in the sulfide solid electrolyte constitutes the current collector foil when the electrode mixture slurry comes into contact with the current collector foil. There was a risk that a reaction to generate copper sulfide (CuS) would occur in contact with the copper (Cu). As a result, the performance of the electrode sheet may be deteriorated, and the performance of the sulfide all-solid-state battery produced by using the electrode sheet may be deteriorated.

The present invention has been made in view of the current situation, and is capable of preventing the sulfur component (S) in the sulfide solid electrolyte from coming into contact with the copper (Cu) constituting the current collector foil. An object of the present invention is to provide a method for manufacturing an electrode sheet for a battery.

One aspect of the present invention is to form a porous conductive layer containing no sulfide solid electrolyte on the surface of a current collector foil made of copper foil in a method for producing an electrode sheet used for a sulfide all-solid battery. A step of producing a current collecting foil with a porous conductive layer, and an electrode mixture composed of a plurality of wet granulated bodies obtained by mixing an electrode active material, a binder, the sulfide solid electrolyte, and a solvent. The electrode mixture is compressed and formed into a film by passing it through the gap between a pair of rolls that rotate in opposition to each other, and the electrode mixture formed into a film is made into the porous of the current collecting foil with the porous conductive layer. This is a method for producing an electrode sheet for a sulfide all-solid-state battery, comprising a step of adhering to the surface of a quality conductive layer to produce the electrode sheet.

In the above-mentioned manufacturing method, first, a porous conductive layer containing no sulfide solid electrolyte is formed on the surface of the current collector foil made of copper foil to prepare a current collector foil with a porous conductive layer. In this way, by preventing the porous conductive layer formed on the surface of the current collector foil made of copper foil from containing the sulfide solid electrolyte, "porous on the surface of the current collector foil made of copper foil". When the conductive layer is formed, the sulfur component (S) in the sulfide solid electrolyte comes into contact with the copper (Cu) constituting the current collecting foil, so that a reaction to generate copper sulfide (CuS) occurs. " Can be prevented.

Further, in the above-mentioned production method, an electrode mixture composed of a plurality of wet granulated materials (wet powders) obtained by mixing an electrode active material, a binder, a sulfide solid electrolyte and a solvent is opposed to each other. By passing the electrode mixture through the gaps between the pair of rotating rolls, the electrode mixture is compressed into a film, and the film-shaped electrode mixture is placed on the surface of the porous conductive layer of the current collector foil with the porous conductive layer. To prepare an electrode sheet.

Here, the wet granulated body is a substance (granular body) in which a solvent is held (absorbed) by a plurality of electrode active materials, a sulfide solid electrolyte, and a binder, and these are aggregated (bonded). , Has no fluidity. Further, the electrode mixture composed of a plurality of wet granulation bodies is an aggregate of such wet granulation bodies and has no fluidity. The solid content of the wet granulated body and the electrode mixture is, for example, a value in the range of 70 to 95 wt%.

As described above, in the above-mentioned manufacturing method, as the electrode mixture to be adhered to the surface of the porous conductive layer among the current collector foils with the porous conductive layer, an electrode mixture made of a wet granulated body having no fluidity is used. I'm using it. Therefore, the electrode mixture adhered to the surface of the porous conductive layer does not permeate (penetrate) into the inside of the porous conductive layer. Therefore, in the above-mentioned manufacturing method, "the electrode mixture adhered on the surface of the porous conductive layer permeates (permeates) into the inside of the porous conductive layer, and becomes a current collector foil made of copper foil. It is possible to prevent "contact".

Therefore, according to the above-mentioned production method, while using the electrode mixture containing the sulfide solid electrolyte as the electrode mixture, "the sulfur component (S) in the sulfide solid electrolyte constitutes the current collecting foil". It is possible to prevent the reaction of generating copper sulfide (CuS) from occurring by coming into contact with the copper (Cu).

The porous conductive layer refers to a porous layer having conductivity, and examples thereof include a porous layer containing a conductive material (particles) and a binder. Further, in addition to the conductive material and the binder, a porous conductive layer containing an electrode active material (equivalent to the electrode active material contained in the electrode mixture) may be used. However, the porous conductive layer should not contain the sulfide solid electrolyte.

The method for forming the porous conductive layer on the surface of the current collecting foil is not particularly limited, but for example, a conductive material (conductive particles), a binder, and a solvent are mixed to form a slurry. A conductive mixture in a state (referred to as a conductive mixture slurry) is prepared, and this conductive mixture slurry is applied onto the surface of the current collector foil by a known die coating and dried to obtain the current collector foil. Examples thereof include a method of forming a porous conductive layer on the surface. The conductive mixture slurry may contain an electrode active material (equivalent to the electrode active material contained in the electrode mixture).

The sulfide solid electrolyte is not particularly limited as long as it contains a sulfur element (S) and has ionic conductivity, but is not particularly limited, and is, for example, Li ₂ SP ₂ S ₅ , Li ₂ SP ₂ S. ₅ -LiI, mention may be made of _{Li 2 S-P 2 S 5} -LiI-LiBr and the like.

It is a flowchart which shows the flow of the manufacturing method of the negative electrode sheet for a sulfide all-solid-state battery which concerns on Examples 1 and 2. It is schematic cross-sectional view of the current collector foil with a porous conductive layer which concerns on Examples 1 and 2. It is the schematic of the roll film forming apparatus which concerns on Examples 1 and 2. It is a perspective schematic view of the roll film forming apparatus. It is schematic cross-sectional view of the negative electrode sheet for a sulfide all-solid-state battery which concerns on Examples 1 and 2.

(Example 1)
Hereinafter, Example 1 embodying the present invention will be described in detail with reference to the drawings. In the first embodiment, the present invention is applied to the production of a negative electrode sheet used for a sulfide all-solid-state battery. In the first embodiment, the current collecting foil 7 made of copper foil, the porous conductive layer 35 (first layer) formed on the surface of the current collecting foil 7, and the surface of the porous conductive layer 35. A negative electrode sheet 19 (see FIG. 5) for a sulfide all-solid-state battery having the formed negative electrode mixture layer 8 (second layer) is manufactured.

Here, the method for manufacturing the negative electrode sheet 19 for a sulfide all-solid-state battery according to the first embodiment will be described in detail. FIG. 1 is a flowchart showing a flow of a manufacturing method of the negative electrode sheet 19 for a sulfide all-solid-state battery according to the first embodiment. FIG. 2 is a schematic cross-sectional view of the current collector foil 39 with a porous conductive layer according to the first embodiment. FIG. 3 is a schematic view of a roll film forming apparatus 20 for manufacturing a negative electrode sheet 19 for a sulfide all-solid-state battery. FIG. 4 is a schematic perspective view of the roll film forming apparatus 20. FIG. 5 is a schematic cross-sectional view of the negative electrode sheet 19 for a sulfide all-solid-state battery.

As shown in FIG. 1, first, in step S1 (a step of producing a current collector foil with a porous conductive layer), a current collector foil 39 with a porous conductive layer is produced. Specifically, first, a negative electrode active material, a conductive material, a binder, and a solvent are mixed to prepare a conductive mixture in a slurry state (referred to as a conductive mixture slurry). In step S1 (the step of producing a current collector foil with a porous conductive layer) of the first embodiment, Si particles are used as the negative electrode active material (electrode active material). Moreover, carbon nanotubes are used as a conductive material. In addition, a fluorine-based binder is used as the binder. Moreover, n-butyl butyrate is used as a solvent. The solid content of the conductive mixture slurry is, for example, a value in the range of 40 to 60 wt%.

Next, this conductive mixture slurry is applied onto the surface of the current collector foil 7 made of copper foil by a known die coating, and then dried (the solvent of the conductive mixture slurry is removed). As a result, the porous conductive layer 35 (dried conductive mixture slurry) is formed on the surface of the current collector foil 7. In this way, a current collector foil 39 with a porous conductive layer (see FIG. 2) having a current collector foil 7 and a porous conductive layer 35 formed on the surface thereof is produced.

By the way, when the conductive mixture slurry contains a sulfide solid electrolyte, when the conductive mixture slurry is applied onto the surface of the current collector foil 7 made of copper foil, it is contained in the conductive mixture slurry. There is a possibility that the sulfur component (S) in the sulfide solid electrolyte may come into contact with the copper (Cu) constituting the current collector foil 7 to cause a reaction in which copper sulfide (CuS) is generated. When the porous conductive layer formed on the surface of the current collector foil 7 made of copper foil contains a sulfide solid electrolyte, the sulfur component in the sulfide solid electrolyte contained in the porous conductive layer (in addition, When S) comes into contact with copper (Cu) constituting the current collecting foil, there is a possibility that a reaction to generate copper sulfide (CuS) may occur. As a result, the performance of the negative electrode sheet for the sulfide all-solid-state battery may deteriorate, and the performance of the sulfide all-solid-state battery produced by using the negative electrode sheet for the sulfide all-solid-state battery may deteriorate.

On the other hand, in the first embodiment, the conductive mixture slurry does not contain the sulfide solid electrolyte. Therefore, the porous conductive layer 35 formed on the surface of the current collector foil 7 made of copper foil does not contain the sulfide solid electrolyte. Therefore, in the first embodiment, "when the conductive mixture slurry is applied on the surface of the current collector foil 7 made of copper foil to form a porous conductive layer, the sulfur component (S) in the sulfide solid electrolyte is used. Can come into contact with the copper (Cu) constituting the current collector foil 7 to prevent a reaction in which copper sulfide (CuS) is generated.

Next, in step S2 (negative electrode mixture manufacturing step), a large number of wet granulated materials 16 (a large number of wet granulated materials 16) are formed by mixing and granulating the negative electrode active material, the conductive material, the binder, the sulfide solid electrolyte, and the solvent. Wet powder) is produced, and a negative electrode mixture 6 composed of a large number of wet granulated materials 16 is produced. Specifically, the negative electrode active material, the conductive material, the binder, the sulfide solid electrolyte, and the solvent are put into a known stirring granulator (not shown) and stirred to obtain the negative electrode active material and the conductivity. The material, the binder, the sulfide solid electrolyte, and the solvent are mixed (dispersed) and granulated to form a large number of wet granulated bodies 16. As a result, the negative electrode mixture 6 composed of a large number of wet granulated bodies 16 can be obtained.

In step S2 (negative electrode mixture manufacturing step) of Example 1, Si particles are used as the negative electrode active material (electrode active material). Moreover, carbon nanotubes are used as a conductive material. In addition, a fluorine-based binder is used as the binder. Moreover, n-butyl butyrate is used as a solvent.

Here, in the wet granulated material 16 (wet powder), the solvent is retained (absorbed) by a plurality of negative electrode active materials (Si particles), a conductive material, a sulfide solid electrolyte, and a binder. Is an aggregated (bonded) substance (granular material) and has no fluidity. Further, the negative electrode mixture 6 composed of the plurality of wet granulated bodies 16 is an aggregate of such wet granulated bodies 16 and has no fluidity. The solid content of the wet granulated body 16 and the negative electrode mixture 6 is set to a value in the range of, for example, 70 to 95 wt%.

Next, the process proceeds to step S3 (negative electrode sheet manufacturing step), and the negative electrode mixture 6 is passed through the gaps between the pair of rolls 1 and 2 that rotate opposite to each other to form a film while compressing the negative electrode mixture 6. The shaped negative electrode mixture 6 (which becomes the negative electrode mixture layer 8) is adhered onto the surface of the porous conductive layer 35 of the current collector foil 39 with the porous conductive layer to form a negative electrode for a sulfide all-solid-state battery. Sheet 19 is produced. In the first embodiment, the roll film forming apparatus 20 shown in FIGS. 3 and 4 is used to perform the process of step S3 (negative electrode sheet manufacturing step).

As shown in FIGS. 3 and 4, the roll film forming apparatus 20 has a first roll 1, a second roll 2, and a third roll 3. The first roll 1 and the second roll 2 are arranged side by side in the horizontal direction (horizontal direction in FIG. 3). On the other hand, the second roll 2 and the third roll 3 are arranged side by side in the vertical direction (vertical direction in FIG. 3). Further, the first roll 1 and the second roll 2 face each other with a slight interval. Similarly, the second roll 2 and the third roll 3 face each other with a slight interval. Further, partition plates 4 and 5 are arranged on the upper side of the facing portion between the first roll 1 and the second roll 2 so as to be separated from each other in the width direction of the roll (axial direction, direction orthogonal to the paper surface in FIG. 3). ing.

Further, the rotation directions of these three rolls 1 to 3 are such that the rotation directions of the two adjacent (facing) rolls are opposite to each other, that is, facing each other, as shown by the arrows in FIGS. 3 and 4. The two rolls are set to rotate forward with each other. Then, at the points where the first roll 1 and the second roll 2 face each other, the surfaces of these rolls move downward due to rotation. Further, at the points where the second roll 2 and the third roll 3 face each other, the surfaces of these rolls move to the right by rotation. Further, regarding the rotation speed, the moving speed of the surface of the roll due to rotation is set to be the slowest in the first roll 1, the fastest in the third roll 3, and intermediate between them in the second roll 2.

In such a roll film forming apparatus 20, step S2 (negative electrode mixture manufacturing step) is performed in the accommodation space between the partition plates 4 and 5 located above the facing portions of the first roll 1 and the second roll 2. The negative electrode mixture 6 produced in 1 is charged. Further, the current collector foil 39 with the porous conductive layer produced in step S1 (the step of producing the current collector foil with the porous conductive layer) is hung on the third roll 3. The current collecting foil 39 with the porous conductive layer is conveyed from the lower left to the upper right of the third roll 3 through the facing portion between the second roll 2 and the third roll 3 as the third roll 3 rotates. It has become.

The current collecting foil 39 with the porous conductive layer is hung on the third roll 3 in the direction in which the current collecting foil 7 of the current collecting foil 39 with the porous conductive layer comes into contact with the third roll 3. In other words, in the current collecting foil 39 with the porous conductive layer, the porous conductive layer 35 faces the second roll 2 side at the position where the second roll 2 and the third roll 3 face each other, and the third roll It is hung on 3.

Further, in a state where the current collecting foil 39 with the porous conductive layer is passed through the portion where the second roll 2 and the third roll 3 face each other, the current collecting foil 39 with the porous conductive layer is further passed through the second roll 2. There is a slight gap between the and. That is, the gap between the second roll 2 and the third roll 3 (the gap in the state where the current collector foil 39 with the porous conductive layer does not exist) is larger than the thickness of the current collector foil 39 with the porous conductive layer. It's a little wide.

In this step S3 (negative electrode sheet manufacturing step), the negative electrode mixture 6 produced in step S2 (negative electrode mixture manufacturing step) is put into the accommodation space between the partition plates 4 and 5 of the roll film forming apparatus 20. The charged negative electrode mixture 6 is supplied into the gap between the first roll 1 and the second roll 2 and passes through the gap between the first roll 1 and the second roll 2 due to the rotation of the first roll 1 and the second roll 2. By doing so, it is compressed into a film (see FIG. 3). At this time, since the rotation speed of the second roll 2 is faster than that of the first roll 1, the wet granulated body 16 contained in the negative electrode mixture 6 is on the surface of the second roll 2 rather than the surface of the first roll 1. It is stretched to a greater extent and is supported on the surface of the second roll 2.

The film-like negative electrode mixture 6 (which becomes the negative electrode mixture layer 8) supported on the surface of the second roll 2 is conveyed with the rotation of the second roll 2 (see FIGS. 3 and 4). Then, at the position where the second roll 2 and the third roll 3 face each other, the porous conductive layer 35 of the current collector foil 39 with the porous conductive layer and the film-like negative electrode mixture 6 meet. As a result, the film-like negative electrode mixture 6 is rotated from the second roll 2 together with the third roll 3 having a faster moving speed on the surface of the porous conductive layer 35 of the current collector foil 39 with the porous conductive layer. Is transferred (attached) to. As a result, the negative electrode sheet 19 for a sulfide all-solid-state battery in which the negative electrode mixture layer 8 is formed on the surface of the porous conductive layer 35 among the current collecting foil 39 with the porous conductive layer can be obtained. The negative electrode sheet 19 for a sulfide all-solid-state battery is then dried by a known drying device to remove (evaporate) the solvent contained in the negative electrode mixture layer 8 (wet granulated body 16). Is preferable.

By the way, unlike the first embodiment, it is possible to form the negative electrode mixture layer on the surface of the porous conductive layer 35 of the current collector foil 39 with the porous conductive layer by the following method. Specifically, first, a negative electrode active material, a conductive material, a sulfide solid electrolyte, a binder, and a solvent are mixed to prepare a negative electrode mixture in a slurry state (referred to as a negative electrode mixture slurry). Next, this negative electrode mixture slurry is applied onto the surface of the porous conductive layer 35 of the current collector foil 39 with the porous conductive layer by a known die coating, and then dried (negative electrode mixture slurry). Remove the solvent from). As a result, a negative electrode sheet for a sulfide all-solid-state battery in which a negative electrode mixture layer is formed on the surface of the porous conductive layer 35 among the current collecting foil 39 with the porous conductive layer can be obtained.

However, in the above method, since the negative electrode mixture slurry has fluidity, when the negative electrode mixture slurry is applied onto the surface of the porous conductive layer 35 of the current collector foil 39 with the porous conductive layer. The negative electrode mixture slurry may permeate (permeate) into the inside of the porous conductive layer 35 and come into contact with the current collecting foil 7 made of copper foil. Since the negative electrode mixture slurry contains a sulfide solid electrolyte, when the negative electrode mixture slurry comes into contact with the current collector foil 7, the sulfur component (S) in the sulfide solid electrolyte is removed from the current collector foil 7. There was a risk that a reaction to generate copper sulfide (CuS) would occur in contact with the copper (Cu) constituting the above. As a result, the performance of the negative electrode sheet for the sulfide all-solid-state battery may be deteriorated, and the performance of the sulfide all-solid-state battery produced by using the negative electrode sheet may be deteriorated.

On the other hand, in the production method of the first embodiment, as described above, the current collecting foil 39 with the porous conductive layer does not have fluidity as a negative electrode mixture to be adhered to the surface of the porous conductive layer 35. A negative electrode mixture 6 made of a wet granulated body 16 is used. Therefore, the negative electrode mixture 6 adhered to the surface of the porous conductive layer 35 does not permeate (penetrate) into the inside of the porous conductive layer 35.

As a result, in the manufacturing method of the first embodiment, "the electrode mixture adhered on the surface of the porous conductive layer permeates (permeates) into the inside of the porous conductive layer and is composed of a copper foil. It is possible to prevent "contact with the current collecting foil". Therefore, according to the production method of the first embodiment, while using the negative electrode mixture 6 containing the sulfide solid electrolyte as the negative electrode mixture (electrode mixture), the "sulfur component in the sulfide solid electrolyte (sulfur component (sulfur component in the sulfide solid electrolyte)" is used. It is possible to prevent "a reaction in which copper sulfide (CuS) is generated occurs when S) comes into contact with copper (Cu) constituting the current collecting foil."

(Example 2)
The production method of the second embodiment is different from the production method of the first embodiment only in step S1 (the step of producing the current collector foil with the porous conductive layer), and the others are the same. Therefore, here, the points different from those of the first embodiment will be mainly described, and the description of the same points will be omitted or simplified.
Also in the second embodiment, the current collecting foil 7 made of copper foil, the porous conductive layer 35 (first layer) formed on the surface of the current collecting foil 7, and the surface of the porous conductive layer 35. A negative electrode sheet 19 (see FIG. 5) for a sulfide all-solid-state battery having the formed negative electrode mixture layer 8 (second layer) is manufactured.

Specifically, in the second embodiment, as shown in FIG. 1, in step T1 (the step of producing the current collecting foil with the porous conductive layer), first, the negative electrode active material, the conductive material, the binder, and the solvent are used. By mixing and granulating, a large number of wet granulated bodies are produced, and a conductive mixture composed of a large number of wet granulated bodies is produced. This conductive mixture is produced by using a known stirring granulator (not shown) in the same manner as the negative electrode mixture 6 (wet granulator 16) of Example 1. However, the conductive mixture does not contain a sulfide solid electrolyte.

In step T1 (step of producing a current collector foil with a porous conductive layer) of Example 2, Si particles are used as the negative electrode active material (electrode active material) as in step S1 of Example 1. .. Moreover, carbon nanotubes are used as a conductive material. In addition, a fluorine-based binder is used as the binder. Moreover, n-butyl butyrate is used as a solvent.

Next, this conductive mixture is adhered in a film form on the surface of the current collector foil 7 made of copper foil to form the porous conductive layer 35 on the surface of the current collector foil 7. Specifically, in step T1 (a step of producing a current collector foil with a porous conductive layer) of the second embodiment, the roll film forming apparatus 20 (FIG. 3 and FIG. 4) are used to form the porous conductive layer 35 on the surface of the current collector foil 7.

More specifically, in the roll film forming apparatus 20, the wet granulation described above is performed in the accommodation space between the partition plates 4 and 5 located above the facing portions of the first roll 1 and the second roll 2. The conductive mixture made of the body is put in. Further, the current collecting foil 7 is hung on the third roll 3, and the current collecting foil 7 passes through the facing portion between the second roll 2 and the third roll 3 as the third roll 3 rotates, and the third roll 3 is subjected to the third roll. The roll 3 is transported from the lower left to the upper right. By doing so, the conductive mixture made of the wet granulated body is made into a film by passing through the gaps between the pair of rolls 1 and 2 that rotate in opposition to each other, and the conductive mixture (which is formed into a film) is formed into a film. (It becomes a conductive mixture layer) adheres to the surface of the current collector foil 7 by passing through the gaps between the rolls 2 and 3.

As a result, a current collector foil 39 with a porous conductive layer (see FIG. 2) having a current collector foil 7 and a porous conductive layer 35 formed on the surface thereof is produced. The produced current collector foil 39 with a porous conductive layer is then dried using a known drying device to remove the solvent contained in the porous conductive layer 35 (wet granulated body) (evaporation). ) Is preferable.

As described above, in step T1 (the step of producing the current collector foil with the porous conductive layer) of the second embodiment, the conductive mixture does not contain the sulfide solid electrolyte. Therefore, the porous conductive layer 35 formed on the surface of the current collector foil 7 made of copper foil does not contain the sulfide solid electrolyte. Therefore, in the second embodiment, "when a conductive mixture is adhered on the surface of the current collector foil 7 made of copper foil to form a porous conductive layer, the sulfur component (S) in the sulfide solid electrolyte is used. Can come into contact with the copper (Cu) constituting the current collector foil 7 to prevent a reaction in which copper sulfide (CuS) is generated.

Then, in step T2 (negative electrode mixture manufacturing step), the negative electrode mixture 6 composed of a large number of wet granulated bodies 16 is produced in the same manner as in step S2 of Example 1.
Next, the process proceeds to step T3 (negative electrode sheet manufacturing step), and in the same manner as in step S3 of Example 1, the negative electrode mixture 6 (which is formed into a film) using the roll film forming apparatus 20 shown in FIGS. 3 and 4 (this is The negative electrode mixture layer 8) is adhered to the surface of the porous conductive layer 35 of the current collector foil 39 with the porous conductive layer to prepare a negative electrode sheet 19 for a sulfide all-solid-state battery.

Also in the production method of the second embodiment, similarly to the first embodiment, the negative electrode mixture to be adhered to the surface of the porous conductive layer 35 of the current collector foil 39 with the porous conductive layer is a wet structure having no fluidity. A negative electrode mixture 6 made of granules 16 is used. Therefore, the negative electrode mixture 6 adhered to the surface of the porous conductive layer 35 does not permeate (penetrate) into the inside of the porous conductive layer 35. As a result, even in the manufacturing method of the second embodiment, "the electrode mixture adhered on the surface of the porous conductive layer permeates (permeates) into the inside of the porous conductive layer and is composed of a copper foil. It is possible to prevent "contact with the current collecting foil". Therefore, even in the production method of the second embodiment, while using the negative electrode mixture 6 containing the sulfide solid electrolyte, "the sulfur component (S) in the sulfide solid electrolyte constitutes copper (condensate foil). Contact with Cu) can prevent a reaction that produces copper sulfide (CuS) from occurring.

(Comparative Example 1)
In Comparative Example 1, unlike Examples 1 and 2, a negative electrode mixture layer is directly formed on the surface of the current collector foil 7 without forming the porous conductive layer 35 on the surface of the current collector foil 7. doing. That is, in the first comparative example, unlike the first and second embodiments, the current collector foil 7 made of copper foil and the negative electrode mixture layer (first layer) formed on the surface of the current collector foil 7 are formed. Manufactures a negative electrode sheet for a sulfide all-solid-state battery.

Specifically, first, a negative electrode active material, a conductive material, a sulfide solid electrolyte, a binder, and a solvent are mixed to prepare a negative electrode mixture in a slurry state (referred to as a negative electrode mixture slurry). Next, this negative electrode mixture slurry is applied onto the surface of the current collector foil 7 made of copper foil by a known die coating, and then dried (the solvent of the negative electrode mixture slurry is removed). In this way, in Comparative Example 1, as the negative electrode sheet for the sulfide all-solid-state battery, the negative electrode sheet for the sulfide all-solid-state battery in which the negative electrode mixture layer is formed on the surface of the current collector foil 7 is produced.

By the way, in the production method of Comparative Example 1, the negative electrode mixture slurry containing the sulfide solid electrolyte is directly applied on the surface of the current collector foil 7. Therefore, the sulfide solid electrolyte contained in the negative electrode mixture slurry comes into contact with the current collector foil 7, whereby the sulfur component (S) in the sulfide solid electrolyte comes into contact with the copper (Cu) that constitutes the current collector foil 7. ), Copper sulfide (CuS) may be generated. As a result, the performance of the negative electrode sheet for the sulfide all-solid-state battery may deteriorate, and the performance of the sulfide all-solid-state battery produced by using the negative electrode sheet may deteriorate.

(Comparative Example 2)
Also in Comparative Example 2, unlike Examples 1 and 2, a negative electrode mixture layer is directly formed on the surface of the current collector foil 7 without forming the porous conductive layer 35 on the surface of the current collector foil 7. doing. That is, in the second comparative example, unlike the first and second embodiments, the current collector foil 7 made of copper foil and the negative electrode mixture layer (first layer) formed on the surface of the current collector foil 7 are formed. Manufactures a negative electrode sheet for a sulfide all-solid-state battery. However, unlike Comparative Example 1, a negative electrode sheet for a sulfide all-solid-state battery is produced by using a negative electrode mixture composed of a plurality of wet granulated bodies.

Specifically, first, in the same manner as in step S2 of Example 1, a negative electrode mixture composed of a large number of wet granulated bodies is produced. As in Example 1, the negative electrode mixture contains a sulfide solid electrolyte. Specifically, a large number of wet granulated materials (wet powders) are produced by mixing and granulating a negative electrode active material, a conductive material, a binder, a sulfide solid electrolyte, and a solvent, and a large number of them. A negative electrode mixture made of the wet granulated material of No. 1 is produced.

Next, in the same manner as in step S3 of Example 1, using the roll film forming apparatus 20 shown in FIGS. 3 and 4, a negative electrode mixture composed of a plurality of wet granulated bodies is formed on the surface of the current collector foil 7. Attach to the shape. As a result, a negative electrode sheet for a sulfide all-solid-state battery in which a negative electrode mixture layer is formed on the surface of the current collector foil 7 is produced.

Also in the production method of Comparative Example 2 described above, the negative electrode mixture containing the sulfide solid electrolyte is directly adhered to the surface of the current collector foil 7. Therefore, the sulfide solid electrolyte contained in the negative electrode mixture comes into contact with the current collector foil 7, whereby the sulfur component (S) in the sulfide solid electrolyte comes into contact with the copper (Cu) constituting the current collector foil 7. There is a risk that copper sulfide (CuS) will be generated in response to. As a result, the performance of the negative electrode sheet for the sulfide all-solid-state battery may deteriorate, and the performance of the sulfide all-solid-state battery produced by using the negative electrode sheet may deteriorate.

(Comparative Example 3)
In Comparative Example 3, unlike Examples 1 and 2, a slurry-state negative electrode mixture (negative electrode mixture slurry) was applied onto the surface of the porous conductive layer 35 of the current collector foil 39 with the porous conductive layer. To produce a negative electrode sheet for a sulfide all-solid-state battery.
In Comparative Example 3, the current collecting foil 7 made of copper foil, the porous conductive layer 35 (first layer) formed on the surface of the current collecting foil 7, and the surface of the porous conductive layer 35. A negative electrode sheet for a sulfide all-solid-state battery having a formed negative electrode mixture layer (second layer) is manufactured.

Specifically, first, a current collector foil 39 with a porous conductive layer is produced in the same manner as in step S1 of Example 1. In addition, also in this Comparative Example 3, the sulfide solid electrolyte is not contained in the porous conductive layer 35 (conductive mixture) as in Example 1.

Then, unlike Example 1, the negative electrode active material, the conductive material, the sulfide solid electrolyte, the binder, and the solvent are mixed to prepare a negative electrode mixture in a slurry state (referred to as a negative electrode mixture slurry). Next, this negative electrode mixture slurry is applied onto the surface of the porous conductive layer 35 of the current collector foil 39 with the porous conductive layer by a known die coating, and this is dried (solvent of the negative electrode mixture slurry). To remove). In this way, the negative electrode sheet for a sulfide all-solid-state battery in which the negative electrode mixture layer is formed on the surface of the porous conductive layer 35 of the current collector foil 39 with the porous conductive layer is produced.

(Comparative Example 4)
In Comparative Example 4, unlike Examples 1 and 2, a slurry-state negative electrode mixture (negative electrode mixture slurry) was applied onto the surface of the porous conductive layer 35 of the current collector foil 39 with the porous conductive layer. To produce a negative electrode sheet for a sulfide all-solid-state battery. However, in Comparative Example 4, the current collecting foil 39 with the porous conductive layer is produced in the same manner as in Example 2.
In Comparative Example 4, the current collecting foil 7 made of copper foil, the porous conductive layer 35 (first layer) formed on the surface of the current collecting foil 7, and the surface of the porous conductive layer 35. A negative electrode sheet for a sulfide all-solid-state battery having a formed negative electrode mixture layer (second layer) is manufactured.

Specifically, first, a current collector foil 39 with a porous conductive layer is produced in the same manner as in step T1 of Example 2. That is, in the same manner as in step T1 of Example 2, a conductive mixture made of a large number of wet granulated bodies is produced, and the conductive mixture is used in a roll film forming apparatus 20 (see FIGS. 3 and 4). , The current collector foil 39 with a porous conductive layer is produced by adhering it on the surface of the current collector foil 7 in the form of a film. In Comparative Example 4, as in Example 2, the porous conductive layer 35 (conductive mixture) does not contain the sulfide solid electrolyte.

Then, in the same manner as in Comparative Example 3, a negative electrode mixture (negative electrode mixture slurry) in a slurry state was prepared, and the negative electrode mixture slurry was used in the porous conductive layer 35 of the current collector foil 39 with the porous conductive layer. Apply on the surface and allow to dry. In this way, the negative electrode sheet for a sulfide all-solid-state battery in which the negative electrode mixture layer is formed on the surface of the porous conductive layer 35 of the current collector foil 39 with the porous conductive layer is produced.

In the manufacturing methods of Comparative Examples 3 and 4 described above, since the negative electrode mixture slurry has fluidity, the negative electrode mixture slurry is used in the porous conductive layer 35 of the current collector foil 39 with the porous conductive layer. When applied on the surface, the negative electrode mixture slurry may permeate (permeate) into the inside of the porous conductive layer 35 and come into contact with the current collecting foil 7 made of copper foil. Since the negative electrode mixture slurry contains a sulfide solid electrolyte, when the negative electrode mixture slurry comes into contact with the current collector foil 7, the sulfur component (S) in the sulfide solid electrolyte is removed from the current collector foil 7. There is a possibility that a reaction to generate copper sulfide (CuS) may occur in contact with copper (Cu) constituting the above. As a result, the performance of the negative electrode sheet for the sulfide all-solid-state battery may deteriorate, and the performance of the sulfide all-solid-state battery produced by using the negative electrode sheet may deteriorate.

(Evaluation test)
Next, the presence or absence of copper sulfide (CuS) was investigated in the negative electrode sheets for sulfide all-solid-state batteries produced by the production methods of Examples 1 and 2 and Comparative Examples 1 to 4.
Specifically, first, using each negative electrode sheet for a sulfide all-solid-state battery (hereinafter, also simply referred to as a negative electrode sheet), the sulfide all-solid-state battery according to Examples 1 and 2 and Comparative Examples 1 to 4 is used. Each was prepared. Next, these sulfide all-solid-state batteries were placed (stored) for 3 days in a temperature environment of 25 ° C. in an inert gas atmosphere. After that, each sulfide all-solid-state battery was disassembled, and each negative electrode sheet was separated from the surface of the current collector foil 7 by 10 μm using a known electron probe microanalyzer (EPMA) (specifically, Element analysis was performed inside the porous conductive layer 35 or inside the negative electrode mixture layer) to investigate the presence or absence of detection of the Cu element. The results are shown in Table 1.

As shown in Table 1, in Comparative Examples 1 and 2, the Cu element was detected in a portion of the negative electrode sheet separated from the surface of the current collector foil 7 by 10 μm (specifically, inside the negative electrode mixture layer). rice field. By the way, in Comparative Examples 1 and 2, when the negative electrode sheet is produced, the Cu element is not contained in the negative electrode mixture slurry. That is, no material containing a Cu element is used as the material constituting the negative electrode mixture slurry. Therefore, it is considered that the Cu element detected inside the negative electrode mixture layer of Comparative Examples 1 and 2 is the Cu element derived from the current collecting foil 7 made of copper foil.

Specifically, when the negative electrode mixture slurry is applied on the surface of the current collector foil 7 to form the negative electrode mixture layer, the sulfur component (S) of the sulfide solid electrolyte contained in the negative electrode mixture slurry is released. It is considered that copper sulfide (CuS) was generated by reacting with the copper (Cu) constituting the current collecting foil 7. It is considered that the Cu component constituting the copper sulfate (CuS) was detected at a portion 10 μm away from the surface of the current collector foil 7 (specifically, inside the negative electrode mixture layer).

Further, as shown in Table 1, also in Comparative Examples 3 and 4, the Cu element was found in the negative electrode sheet at a portion 10 μm away from the surface of the current collector foil 7 (specifically, inside the porous conductive layer 35). Was detected. By the way, in Comparative Examples 3 and 4, when the current collector foil 39 with the porous conductive layer is produced, the Cu element is not contained in the conductive mixture slurry. That is, no material containing a Cu element is used as the material constituting the conductive mixture slurry. Furthermore, when the negative electrode mixture layer is formed on the surface of the porous conductive layer 35 in the current collector foil 39 with the porous conductive layer, the negative electrode mixture slurry does not contain the Cu element. That is, no material containing a Cu element is used as the material constituting the negative electrode mixture slurry. Therefore, it is considered that the Cu element detected inside the porous conductive layer 35 of Comparative Examples 3 and 4 is a Cu element derived from the current collector foil 7 made of copper foil.

Specifically, in order to form the negative electrode mixture layer, the negative electrode mixture slurry coated on the surface of the porous conductive layer 35 among the current collecting foil 39 with the porous conductive layer is inside the porous conductive layer 35. It is probable that it permeated into the current (soaked in) and came into contact with the current collecting foil 7 made of copper foil. As a result, the sulfur component (S) in the sulfide solid electrolyte contained in the negative electrode mixture slurry reacted with the copper (Cu) constituting the current collector foil 7, and copper sulfide (CuS) was generated. Conceivable. It is considered that the Cu component constituting the copper sulfate (CuS) was detected at a portion 10 μm away from the surface of the current collector foil 7 (specifically, inside the porous conductive layer 35).

On the other hand, as shown in Table 1, in Examples 1 and 2, in the negative electrode sheet 19 for the sulfide all-solid-state battery, a portion (specifically, porous conductivity) separated from the surface of the current collector foil 7 by 10 μm. No Cu element was detected in the layer 35). The reason can be considered as follows.

Specifically, first, in Examples 1 and 2, the sulfide solid electrolyte is contained in the conductive mixture for forming the porous conductive layer 35 on the surface of the current collecting foil 7 made of copper foil. No. Therefore, in Examples 1 and 2, "when the conductive mixture slurry is applied on the surface of the current collector foil 7 made of copper foil to form the porous conductive layer 35, the sulfur component in the sulfide solid electrolyte is formed. It is considered that the reaction of generating copper sulfide (CuS) did not occur when (S) came into contact with the copper (Cu) constituting the current collector foil 7. Therefore, it is considered that the Cu element was not detected in the portion of the negative electrode sheet 19 for the sulfide all-solid-state battery 10 μm away from the surface of the current collector foil 7 (specifically, the inside of the porous conductive layer 35). ..

Further, in Examples 1 and 2, the negative electrode mixture made of the wet granulated body 16 having no fluidity as the negative electrode mixture to be adhered to the surface of the porous conductive layer 35 in the current collecting foil 39 with the porous conductive layer. Material 6 is used. Therefore, it is considered that the negative electrode mixture 6 adhered to the surface of the porous conductive layer 35 could be prevented from permeating (permeating) into the inside of the porous conductive layer 35. It is considered that this prevented the sulfur component (S) in the sulfide solid electrolyte contained in the negative electrode mixture 6 from coming into contact with the copper (Cu) constituting the current collector foil.

Therefore, in Examples 1 and 2, while using the negative electrode mixture 6 containing the sulfide solid electrolyte, "the sulfur component (S) in the sulfide solid electrolyte is copper (Cu) constituting the current collecting foil. It is considered that the reaction of copper sulfide (CuS) generation could be prevented by contacting with. Therefore, it is considered that the Cu element was not detected in the portion (specifically, the inside of the porous conductive layer 35) separated from the surface of the current collector foil 7 by 10 μm in the negative electrode sheet 19 for the sulfide all-solid-state battery. Be done.

Although the present invention has been described above with reference to Examples 1 and 2, the present invention is not limited to Examples 1 and 2, and can be appropriately modified and applied without departing from the gist thereof. Needless to say.

For example, in Examples 1 and 2, a method of manufacturing a negative electrode sheet (negative electrode sheet for a sulfide all-solid-state battery 19) as an electrode sheet for a sulfide all-solid-state battery was exemplified. However, the present invention can also be applied to a method for producing a positive electrode sheet (positive electrode sheet for a sulfide all-solid-state battery).

1 1st roll 2 2nd roll 6 Negative electrode mixture (electrode mixture)
7 Current collector foil 8 Negative electrode mixture layer 16 Wet granulated body 19 Negative sheet for sulfide all-solid-state battery (Electrode sheet for sulfide all-solid-state battery)
20 Roll film forming apparatus 35 Porous conductive layer 39 Current collector foil with porous conductive layer

Claims (1)

In the method for manufacturing an electrode sheet used for a sulfide all-solid-state battery,
A step of producing a current collector foil with a porous conductive layer by forming a porous conductive layer that does not contain a sulfide solid electrolyte on the surface of a current collector foil made of copper foil.
By passing an electrode mixture composed of a plurality of wet granulated bodies granulated by mixing an electrode active material, a binder, the sulfide solid electrolyte, and a solvent through a gap between a pair of rolling rolls facing each other. The electrode mixture is compressed into a film, and the film-shaped electrode mixture is adhered to the surface of the porous conductive layer of the current collecting foil with the porous conductive layer to form the electrode sheet. And a method for manufacturing an electrode sheet for a sulfide all-solid-state battery.

Images