JP2010186682A - Method of manufacturing solid electrolyte layer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid electrolyte layer in which an amount of binder polymer is reduced by combining a sulfur component in a sulfide-based solid electrolyte material with double bonds in the binding polymer and thereby lithium ion conductivity is improved, without flexibility and workability being reduced. <P>SOLUTION: There is provided a method of manufacturing a solid electrolyte layer. The method includes: a solid electrolyte layer-forming slurry preparation step in which a sulfide-based solid electrolyte material and a binder polymer having double bonds capable of bonding with a sulfur component are mixed in a solvent to obtain a solid electrolyte layer-forming slurry; and a combining step in which the solid electrolyte layer-forming slurry is subjected to combining treatment to combine the sulfur component in the sulfide-based solid electrolyte material with the double bonds in the binding polymer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention reduces the amount of the binder polymer by reducing the flexibility and processability by combining the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer. The present invention relates to a solid electrolyte layer having improved lithium ion conductivity.

  With the rapid spread of information-related equipment and communication equipment such as personal computers, video cameras, and mobile phones in recent years, development of batteries that are used as power sources has been regarded as important. Also in the automobile industry and the like, development of high-power and high-capacity batteries for electric vehicles or hybrid vehicles is being promoted. Currently, lithium batteries are attracting attention among various batteries from the viewpoint of high energy density.

  The lithium battery currently on the market uses an organic electrolyte that uses a flammable organic solvent as a solvent. Improvement is required.

  In contrast, an all-solid-state lithium battery in which the liquid electrolyte is changed to a solid electrolyte to make the battery all solid does not use a flammable organic solvent in the battery. It is considered to be excellent in productivity.

  Such an all-solid lithium secondary battery includes a positive electrode layer and a negative electrode layer (hereinafter sometimes simply referred to as an electrode layer), and a solid electrolyte layer disposed between them. Consists of. Also, when the electrode layer is formed by powder molding using only the electrode active material, the electrolyte is solid, so that the electrolyte hardly penetrates into the electrode layer, the interface between the electrode active material and the electrolyte is reduced, and the battery Performance will be degraded. Therefore, the area of the interface is usually increased by forming an electrode layer using an electrode mixture containing a mixed powder obtained by mixing an electrode active material powder and an electrolyte powder.

Since such an all-solid lithium secondary battery is composed of a solid, the flexibility and workability are poor, and it is difficult to reduce the thickness and area of the electrolyte layer. Moreover, since the handleability at the time of battery manufacture was bad, the improvement regarding this point was also calculated | required.
Therefore, in order to give flexibility to an all-solid lithium secondary battery, for example, Patent Document 1 discloses a binder polymer composed of 1,2 polybutadiene and polar rubber, a solid electrolyte molded body including these, and A solid state battery is disclosed. By including the binder polymer, this is flexible and excellent in workability.

  However, polymer compounds such as binder polymers generally tend to inhibit lithium ion migration and inhibit electrochemical reactions that occur at the electrode / electrolyte interface, as well as lithium ion diffusion in the electrolyte and in the electrode. . Therefore, there is still a problem that the addition of a polymer compound such as a binder polymer in order to improve flexibility and the like, the lithium ion conductivity is lowered and the operating characteristics of the electrochemical device are lowered. .

JP 2000-123874 A JP 2008-21416 A

T.A. Inada, et al. , “Fabrications and properties of composite solid-state electronics”, Solid State Ionics. , Vol 158, Issues 3-4, March 2003, p275-280

  The present invention has been made in view of the above problems, and a solid electrolyte layer having improved lithium ion conductivity by reducing the amount of binder polymer without reducing flexibility and workability. The main purpose is to provide.

  In order to achieve the above object, in the present invention, a solid electrolyte layer is formed by mixing a sulfide-based solid electrolyte material and a binder polymer having a double bond capable of binding to a sulfur component in a solvent. The solid electrolyte layer forming slurry preparation step for obtaining a slurry, and the solid electrolyte layer forming slurry are combined to combine the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer. Provided is a method for producing a solid electrolyte layer, comprising a bonding treatment step.

  According to the present invention, by binding the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer, the amount of the binder polymer can be reduced without reducing flexibility and workability. A solid electrolyte layer with improved lithium ion conductivity can be obtained by decreasing the amount.

  In the said invention, it is preferable that the said joint process is heat processing. This is because it is possible to simply perform a bonding treatment for bonding the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer.

  In the said invention, it is preferable that the temperature of the said heat processing exists in the range of 100 to 200 degreeC. By performing the heat treatment within the above temperature range, it is possible to more effectively perform the bonding treatment for bonding the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer. is there.

  In the said invention, it is preferable that the said solvent is a fluorine-type solvent. This is because the reaction between the sulfide-based solid electrolyte material and the solvent can be suppressed, and decomposition of the sulfide-based solid electrolyte material can be suppressed.

  In the said invention, it is preferable to have a coupling | bonding promotion sulfur containing material addition process. This is because the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer can be bonded more effectively.

  In the present invention, an electrode active material, a sulfide-based solid electrolyte material, and a binder polymer having a double bond capable of binding to a sulfur component are mixed in a solvent to obtain an electrode layer forming slurry. An electrode layer forming slurry preparation step to be obtained, and a binding treatment step for binding the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer by binding the electrode layer forming slurry. The manufacturing method of the electrode layer characterized by having is provided.

  According to the present invention, by binding the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer, the amount of the binder polymer can be reduced without reducing flexibility and workability. An electrode layer with improved lithium ion conductivity can be obtained by reducing the amount.

  In the said invention, it is preferable that the said joint process is heat processing. This is because it is possible to simply perform a bonding treatment for bonding the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer.

  In the said invention, it is preferable that the temperature of the said heat processing exists in the range of 100 to 200 degreeC. By performing the heat treatment within the above temperature range, it is possible to more effectively perform the bonding treatment for bonding the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer. is there.

  In the said invention, it is preferable that the said solvent is a fluorine-type solvent. This is because the reaction between the sulfide-based solid electrolyte material and the solvent can be suppressed, and decomposition of the sulfide-based solid electrolyte material can be suppressed.

  In the said invention, it is preferable to have a coupling | bonding promotion sulfur containing material addition process. This is because the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer can be bonded more effectively.

  In the present invention, a battery element forming step of forming a battery element using at least one of the solid electrolyte layer obtained by the method for producing a solid electrolyte layer or the electrode layer obtained by the method for producing an electrode layer A method for producing an all-solid lithium secondary battery is provided.

  According to the present invention, the amount of the binder polymer is reduced by using at least one of the solid electrolyte layer obtained by the method for producing the solid electrolyte layer or the electrode layer obtained by the method for producing the electrode layer. Thus, an all-solid lithium secondary battery with improved lithium ion conductivity can be obtained.

  Further, in the present invention, at least the sulfide-based solid electrolyte material and a binder polymer having a double bond capable of binding to the sulfur component, the sulfur component in the sulfide-based solid electrolyte material and the above-mentioned Provided is a solid electrolyte layer characterized by having a site where a double bond of a binder polymer is bonded.

  According to the present invention, by having a site where the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer are bonded to each other, it is possible to bind without reducing flexibility and workability. A solid electrolyte layer with improved lithium ion conductivity can be obtained by reducing the amount of the adsorbent polymer.

  In the present invention, at least the electrode active material, the sulfide-based solid electrolyte material, and the binder polymer having a double bond capable of binding to the sulfur component are contained in the sulfide-based solid electrolyte material. There is provided an electrode layer characterized in that it has a site where the sulfur component of the above and the double bond of the binder polymer are bonded.

  According to the present invention, by having a site where the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer are bonded to each other, it is possible to bind without reducing flexibility and workability. An electrode layer with improved lithium ion conductivity can be obtained by reducing the amount of the adhering polymer.

  The present invention also provides an all solid lithium secondary battery using at least one of the solid electrolyte layer and the electrode layer.

  According to the present invention, by using at least one of the solid electrolyte layer or the electrode layer, an all solid lithium secondary battery having an improved lithium ion conductivity can be obtained by reducing the amount of the binder polymer. Can do.

  In the present invention, by binding the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer, the amount of the binder polymer is reduced without reducing flexibility and workability. Thus, there is an effect that a solid electrolyte layer having improved lithium ion conductivity can be obtained.

It is a solid electrolyte layer formation flowchart which shows an example of the manufacturing method of the solid electrolyte layer of this invention. It is a schematic sectional drawing which shows typically an example of the all-solid-state lithium secondary battery obtained by this invention. It is a graph which shows the suitable heat processing conditions in an Example.

A. The manufacturing method of a solid electrolyte layer The manufacturing method of the solid electrolyte layer of this invention is demonstrated in detail below.
In the method for producing a solid electrolyte layer of the present invention, a solid electrolyte layer forming slurry is prepared by mixing a sulfide-based solid electrolyte material and a binder polymer having a double bond capable of binding to a sulfur component in a solvent. A solid electrolyte layer forming slurry preparation step to be obtained, and a binding process for binding the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer by binding the solid electrolyte layer forming slurry It has the process, It is characterized by the above-mentioned.

According to the present invention, by binding the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer, the amount of the binder polymer can be reduced without reducing flexibility and workability. A solid electrolyte layer with improved lithium ion conductivity can be obtained by decreasing the amount. This is considered to be due to the following reasons.
In order to give flexibility to the solid electrolyte layer, a binder polymer is added. However, since a polymer compound such as a binder polymer generally tends to inhibit the movement of lithium ions, the binder is used. It is preferred to reduce the polymer content.
However, conventionally, since the solid electrolyte layer and the binder polymer are simply mixed, the sulfide-based solid electrolyte material and the binder polymer are bonded only by intermolecular force. In addition, the bonding force between the sulfide-based solid electrolyte material and the binder polymer is small. For this reason, if the binder polymer content for imparting flexibility to the solid electrolyte layer is reduced, sufficient flexibility such as cracking of the solid electrolyte layer cannot be obtained, and the binder polymer content is reduced. It was difficult to reduce. Therefore, when sufficient flexibility and workability are to be maintained, there has been a problem that the lithium ion conductivity is lowered by the binder polymer in the solid electrolyte layer.
On the other hand, in the present invention, the sulfur component in the sulfide-based solid electrolyte material is bound to the sulfur component in the sulfide-based solid electrolyte material by bonding the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer by the bonding treatment. Since the double bond of the agent polymer is usually bonded by a covalent bond, the bonding force is larger than the case of bonding by only the conventional intermolecular force. For this reason, even when the content of the binder polymer for imparting flexibility to the solid electrolyte layer is reduced, sufficient flexibility can be obtained. Therefore, the binder polymer content can be reduced, and the solid electrolyte layer with improved lithium ion conductivity is obtained by reducing the amount of binder polymer without reducing flexibility and workability. It can be done.

Specifically, according to the solid electrolyte layer formation flow chart as shown in FIG. 1, a solid electrolyte layer can be obtained through the following steps.
For example, first, in a mechanical milling step, a sulfide-based solid electrolyte material raw material powder is added to a pot together with a ball and mechanically milled to obtain a sulfide-based solid electrolyte material mixed powder.
Next, in the sulfide-based solid electrolyte material forming step, the sulfide-based solid electrolyte material mixed powder is partially crystallized by heat treatment at a predetermined temperature and time, and the sulfide-based solid electrolyte material is obtain.
Next, in the solid electrolyte layer forming slurry preparation step, the above-mentioned sulfide-based solid electrolyte material and a binder polymer having a double bond capable of binding to the sulfur component are mixed in a solvent, thereby forming a solid electrolyte layer forming slurry. Get.
In the bonding treatment step, after applying the solid electrolyte layer forming slurry on the base material, for example, heat treatment is performed as a bonding treatment to evaporate the solvent, and the sulfur component in the sulfide solid electrolyte material and A solid electrolyte layer can be obtained by bonding the double bond of the binder polymer.

The method for producing a solid electrolyte layer of the present invention is not particularly limited as long as it is a production method having a solid electrolyte layer forming slurry preparation step and a binding treatment step, and may have other steps. good.
Hereinafter, each process in the manufacturing method of the solid electrolyte layer of this invention is demonstrated in detail.

1. Solid electrolyte layer forming slurry preparation step The solid electrolyte layer forming slurry preparation step in the present invention is a method in which a sulfide-based solid electrolyte material and a binder polymer having a double bond capable of binding to a sulfur component are mixed in a solvent. This is a step of obtaining a solid electrolyte layer forming slurry.
By passing through this step, it is possible to obtain a solid electrolyte layer forming slurry used in the bonding treatment step described later.

The sulfide-based solid electrolyte material used in this step is not particularly limited as long as the sulfur component in the sulfide-based solid electrolyte material can be bonded to the double bond of the binder polymer described later. Absent. Specific examples of the raw material for the sulfide-based solid electrolyte material include Li ₂ S / P ₂ S ₅ , Li ₂ S / Si ₂ S, Li ₂ S / B ₂ S ₃ , Li ₂ S / GeS ₂ , Li ₂ S / Al ₂ S ₃ , a mixture thereof, or the like can be given. Among _them, preferred is _{Li 2 S / P 2 S 5} , in particular, blending _{ratio, Li 2 S: P 2 S} 5 = 60~80: it is preferred an 40-20. This is because these are particularly excellent in ion conduction performance as a solid electrolyte. In addition, an appropriate amount of sulfur may be added to the raw material of the sulfide-based solid electrolyte material described above.

The shape of the sulfide-based solid electrolyte material is not particularly limited as long as it is a shape that can be bonded to the double bond of the binder polymer, but is usually in the form of fine particles. The shape of the fine particles is preferably, for example, spherical or elliptical. The average particle diameter when the sulfide-based solid electrolyte material is fine particles can be, for example, 100 μm or less, and is preferably in the range of 0.1 to 20 μm, particularly preferably in the range of 1 to 10 μm. .
In the present invention, the average particle diameter of the sulfide-based solid electrolyte material can be a value measured based on image analysis using an electron microscope such as SEM.

  Moreover, as a formation method of the said sulfide type solid electrolyte material, it can obtain by passing through the mechanical milling process mentioned later, a sulfide type solid electrolyte material formation process, etc., for example.

The binder polymer used in this step is not particularly limited as long as it has a double bond that can be combined with the sulfur component in the sulfide-based solid electrolyte material. Usually, those used as vulcanizable rubber are preferred. This is because the solid electrolyte layer can be made flexible.
Specific examples of such a binder polymer include styrene-butadiene rubber, ethylene propylene rubber, polybutadiene rubber, styrene-ethylene-butadiene rubber, silicone rubber, butyl rubber, and fluorine rubber. Among these, styrene-butadiene rubber, ethylene propylene rubber, and polybutadiene rubber are preferable. Effectively, the double bond of the binder polymer and the sulfur component in the sulfide-based solid electrolyte material can be bonded, and the conductivity of the polymer can be maintained because the polarity of the polymer is low. is there.

  As the content of the binder polymer, the solid electrolyte layer with improved lithium ion conductivity can be obtained by reducing the amount of the binder polymer without reducing flexibility and workability. If it is content, it will not specifically limit. Specifically, the weight (wt)% of the binder polymer weight with respect to the total weight of the binder polymer and the sulfide-based solid electrolyte material (binder polymer weight / (binder polymer weight + sulfurization). The physical solid electrolyte material weight) × 100) is, for example, in the range of 0.1 to 10 wt%, in particular in the range of 0.1 to 5 wt%, particularly in the range of 0.1% to 1 wt%. Is preferred. If the amount is more than the above range, the lithium ion conductivity of the solid electrolyte layer may be lowered. If the amount is less than the above range, the flexibility of the solid electrolyte layer may be deteriorated.

  As the molecular weight of the binder polymer, the number average molecular weight is preferably in the range of 1,000 to 700,000, more preferably in the range of 10,000 to 100,000, and particularly preferably in the range of 30,000 to 80,000. This is because if the molecular weight of the binder polymer is too small, the flexibility is insufficient, and if it is too large, the solubility is poor and the dispersibility may not be sufficiently secured.

  In this step, a surfactant may be added to the solvent in addition to the sulfide-based solid electrolyte material and the binder polymer. Although it does not specifically limit as said surfactant, Especially, what has polyether, polythiol, etc. which are inactive with respect to electrolyte in a structure is preferable.

  The solvent used in this step is not particularly limited as long as it is a solvent that can stably disperse a sulfide-based solid electrolyte material and a binder polymer having a double bond capable of binding to a sulfur component. It is not something. Specifically, a fluorine solvent, a chlorine solvent, a saturated hydrocarbon solvent, an aromatic solvent, and the like can be given. Among these, the solvent is preferably a fluorine-based solvent. The reaction between the sulfide-based solid electrolyte material and the solvent is suppressed, the decomposition of the sulfide-based solid electrolyte material is suppressed, and the sulfide-based solid electrolyte material can be more reliably combined with the sulfur component. This is because the binder polymer having a heavy bond can be stably dispersed.

  As a specific method for preparing the solid electrolyte layer forming slurry, a sulfide-based solid electrolyte material and a binder polymer having a double bond capable of binding to a sulfur component were mixed and dispersed in a solvent. The method is not particularly limited as long as it is a method capable of obtaining a solid electrolyte layer forming slurry. For example, a method of stirring for a predetermined time after adding the sulfide-based solid electrolyte material and the binder polymer having a double bond capable of binding to a sulfur component to a fluorine-based solvent can be exemplified.

2. Bonding process The bonding process in the present invention is to bond the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer by bonding the solid electrolyte layer forming slurry. It is a process.

  By passing through this step, as described above, the sulfur component in the sulfide-based solid electrolyte material can be bonded to the double bond of the binder polymer, thereby reducing flexibility and workability. Without reducing the amount of the binder polymer, a solid electrolyte layer with improved lithium ion conductivity can be obtained.

The method for performing the bonding treatment in this step is not particularly limited as long as it is a method capable of bonding the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer. Absent. Specific examples include heat treatment, ultraviolet treatment, plasma treatment, radical generation treatment, electron beam treatment, and radiation treatment. Among these, heat treatment is preferable. This is because it is possible to carry out a bonding process for bonding the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer more simply. In addition, when heat treatment is performed as the bonding treatment, the solvent in the solid electrolyte layer forming slurry can also be evaporated through this step.

  When performing the said heat processing, it is preferable as temperature of the said heat processing to exist in the range of 50 to 250 degreeC, especially within the range of 100 to 200 degreeC. This is because by performing the heat treatment within the above temperature range, the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer can be bonded more effectively.

In this step, the solid electrolyte layer forming slurry is subjected to a bonding treatment. Usually, the solid electrolyte layer forming slurry is applied onto a predetermined base material, and the solid electrolyte layer is obtained by performing the above bonding treatment. be able to.
The base material used when performing such coating and the like is not particularly limited. For example, a peelable base material such as a metal foil or a Teflon (registered trademark) sheet is generally used. An electrode layer, an electrode layer obtained by “B. Electrode layer production method” described later, and the like can be used.
When a peelable substrate such as the Teflon (registered trademark) sheet is used, the solid electrolyte layer can be obtained by peeling the solid electrolyte layer portion from the substrate.

3. Other Steps In the present invention, for example, in addition to the above-described solid electrolyte layer forming slurry preparation step and the binding treatment step, other steps may be included as necessary. Specifically, a mechanical milling process for obtaining a sulfide-based solid electrolyte material mixed powder, and for obtaining a sulfide-based solid electrolyte material by partially crystallizing the sulfide-based solid electrolyte material mixed powder. A sulfide-based solid electrolyte material forming step, a dusting step of applying pressure to the solid electrolyte layer obtained in the above-described bonding treatment step, and further, the sulfide-based solid electrolyte material raw material powder, the sulfide-based solid electrolyte material mixed powder Examples include a bond promoting sulfur-containing material addition step of adding a bond promoting sulfur-containing material to the sulfide-based solid electrolyte material.
Hereinafter, other processes such as a mechanical milling process, a sulfide-based solid electrolyte material forming process, a compacting process, and a bond promoting sulfur-containing material adding process will be described in detail.

(1) Mechanical milling step This step is a step of mechanically milling the sulfide-based solid electrolyte material raw material powder to obtain a sulfide-based solid electrolyte material mixed powder.
By passing through this step, a sulfide-based solid electrolyte material mixed powder in which sulfide-based solid electrolyte material raw material powder is uniformly mixed can be obtained.

  The sulfide-based solid electrolyte material raw material powder used in this step is not particularly limited as long as a sulfide-based solid electrolyte material can be obtained. The sulfide-based solid electrolyte material to be obtained is not particularly limited. Depending on the type, it can be selected as appropriate. Specific examples are the same as those described in “1. Solid electrolyte layer forming slurry preparation step” above, and thus description thereof is omitted here.

In this step, in addition to the sulfide-based solid electrolyte material raw material powder, other additives may be added. An example of the additive is at least one lithium orthooxoate selected from the group consisting of Li ₃ PO ₄ , Li ₄ SiO ₄ , Li ₄ GeO ₄ , Li ₃ BO ₃ and Li ₃ AlO _3. it can. By adding such a lithium orthooxo acid, a more stable sulfide-based solid electrolyte can be obtained. The sulfide-based solid electrolyte material raw material powder in the present invention may contain both the sulfide and the lithium orthooxoacid. Moreover, the addition amount of an additive will not be specifically limited if it is a quantity which can obtain the target sulfide type solid electrolyte material.

  The mechanical milling method is not particularly limited as long as a sulfide-based solid electrolyte material mixed powder in which a sulfide-based solid electrolyte material raw material powder is uniformly mixed can be obtained. For example, a ball mill, a turbo mill, a mechano-fusion, a disc mill and the like can be mentioned. Among them, a ball mill is preferable, and a planetary ball mill is particularly preferable. This is because the sulfide-based solid electrolyte material mixed powder can be obtained efficiently.

  The various conditions of the mechanical milling are preferably set to such an extent that a desired sulfide-based solid electrolyte material mixed powder can be obtained, and preferably selected appropriately according to the type of mechanical milling. For example, when the sulfide-based solid electrolyte mixed powder is obtained by a planetary ball mill, the sulfide-based solid electrolyte material raw material powder and pulverizing balls are usually added to the pot and processed at a predetermined rotation speed and time. The number of rotations when performing the planetary ball mill is, for example, preferably in the range of 50 rpm to 500 rpm, and more preferably in the range of 100 rpm to 300 rpm. In addition, the processing time for performing the planetary ball mill is not particularly limited as long as the sulfide-based solid electrolyte material mixed powder in which the sulfide-based solid electrolyte material raw material powder is uniformly mixed can be obtained.

  The sulfide-based solid electrolyte material mixed powder obtained by this step is a mixture of sulfide-based solid electrolyte material raw material powder uniformly, but usually has an amorphous portion.

(2) Sulfide-based solid electrolyte material forming step This step involves heat-treating the sulfide-based solid electrolyte material mixed powder obtained in the mechanical milling step, thereby partially crystallizing the sulfide-based solid electrolyte material. This is a process for obtaining a material.
By passing through this step, a sulfide-based solid electrolyte material used in the solid electrolyte layer forming slurry preparation step can be obtained.

  The heat treatment method is not particularly limited as long as it is a method capable of partially crystallizing the sulfide-based solid electrolyte material mixed powder by heat treatment to obtain the sulfide-based solid electrolyte material. It is not a thing. For example, a method of heating the sulfide-based solid electrolyte material mixed powder in an air atmosphere at a predetermined temperature and time can be exemplified.

  The heat treatment conditions such as atmosphere, temperature, and time for the heat treatment include the formation conditions of the sulfide-based solid electrolyte material mixed powder, that is, the type of the mechanical milling, the conditions for the mechanical milling, the sulfide-based It varies depending on the type of the solid electrolyte material raw material powder and the like, and is not particularly limited as long as desired heat treatment can be performed, and can be appropriately set by conducting a preliminary experiment or the like.

(3) Compacting step This step is a step of applying pressure to the solid electrolyte layer obtained by the above-described bonding treatment step.
By passing through this process, the space | gap in a solid electrolyte layer can be reduced, the contact area of sulfide type solid electrolyte materials in a solid electrolyte layer can be increased, and the performance of a solid electrolyte layer can be improved further.

The method for applying pressure to the solid electrolyte layer is not particularly limited as long as it is a method that can further improve the performance of the solid electrolyte layer by reducing the voids in the solid electrolyte layer, and is usually used. It can carry out using the pressurization apparatus etc. which are currently used.
Further, the pressure to be applied is not particularly limited as long as the pressure in the solid electrolyte layer can be improved by reducing voids in the solid electrolyte layer.

(4) Bond-promoting sulfur-containing material addition step This step is a bond-promoting sulfur that promotes the binding between the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer in the above-described binding treatment step. In this step, the inclusion is added to the sulfide-based solid electrolyte material raw material powder, the sulfide-based solid electrolyte material mixed powder, the sulfide-based solid electrolyte material, or the like.
The bond-promoting sulfur-containing material added in this step can be made into a sulfide-based solid electrolyte material sufficiently containing a sulfur component by being introduced into the sulfide-based solid electrolyte material. Therefore, by using a sulfide-based solid electrolyte material sufficiently containing such a sulfur component, a double bond between the sulfur component in the sulfide-based solid electrolyte material and the binder polymer in the bonding treatment step. Can be easily combined.

This step may be performed before the mechanical milling step, may be performed after the mechanical milling step, and before the sulfide solid electrolyte material forming step, and after the sulfide solid electrolyte material forming step. The solid electrolyte layer forming slurry preparation step may be performed before the step.
As a specific method for adding the bond-promoting sulfur-containing substance, in the above-mentioned bonding treatment step, a bond promotion that promotes bonding between the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer. The method is not particularly limited as long as a desired amount of sulfur-containing material can be added.
Specifically, when this step is performed before the mechanical milling step, a method of adding the bond-promoting sulfur-containing material to the sulfide solid electrolyte material raw material powder used in the mechanical milling step is mentioned. Can do.
Further, when this step is performed after the mechanical milling step and before the sulfide-based solid electrolyte material forming step, the bond-promoting sulfur-containing material is converted into the sulfide-based solid obtained by the mechanical milling step. Examples thereof include a method of adding to the electrolyte material mixed powder. In this case, after the bond-promoting sulfur-containing material is added and before the sulfide-based solid electrolyte material forming step, usually, the sulfide-based solid electrolyte material mixed powder and the bond-promoting sulfur-containing material are uniformly mixed. A mixing step is performed.
Further, when this step is performed after the sulfide-based solid electrolyte material forming step and before the solid electrolyte layer-forming slurry preparation step, the bond-promoting sulfur-containing material is converted into the sulfide-based solid electrolyte material forming step. The method of adding to the said sulfide type solid electrolyte material obtained by (1) etc. can be mentioned. In this case, after adding the bond-promoting sulfur-containing material, a mixing step of uniformly mixing the sulfide-based solid electrolyte material and the bond-promoting sulfur-containing material is performed, and heat treatment is performed again by the sulfide-based solid electrolyte material forming step. By performing the step, it is possible to form a sulfide-based solid electrolyte material sufficiently containing a sulfur component.

  Specific examples of the bond promoting sulfur-containing material used in this step include sulfur, phosphorus and selenium. Of these, sulfur is preferred. This is because the bonding can be promoted more surely in the above-described bonding processing step.

  The amount of the bond-promoting sulfur-containing material added is such that the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer are easily bonded in the bonding treatment step. There is no particular limitation as long as it is present. Specifically, for example, when the bond promoting sulfur-containing material is simple sulfur (S), the weight (wt)% of the sulfur weight with respect to the total weight of the sulfur and the sulfide-based solid electrolyte material ( Sulfur weight / (sulfur weight + sulfide-based solid electrolyte material weight) × 100) is preferably in the range of 0.1 to 5 wt%, and more preferably in the range of 0.1 to 1 wt%. This is because if it is within the above range, the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer are more easily bonded in the bonding treatment step.

(5) Other process Moreover, before the said mechanical milling process, it has a sulfide type solid electrolyte material raw material powder preparation process which mixes sulfide type solid electrolyte material raw material powder using an agate mortar etc., for example. Also good.
In addition, as described above, after the mechanical milling step, when adding a bond-promoting sulfur-containing material, if necessary, a mixing step of mixing after adding the bond-promoting sulfur-containing material may be performed. .

4). Others The solid electrolyte layer obtained by the production method of the present invention is useful, for example, as a solid electrolyte layer for an all solid-state lithium battery.

B. The manufacturing method of an electrode layer The manufacturing method of the electrode layer of this invention is demonstrated in detail below.
The method for producing an electrode layer according to the present invention comprises mixing an electrode active material, a sulfide-based solid electrolyte material, and a binder polymer having a double bond capable of binding to a sulfur component in a solvent. An electrode layer forming slurry preparation step for obtaining a forming slurry, and a bond for binding the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer by binding the electrode layer forming slurry. It has a processing step.

In an all-solid lithium secondary battery, when an electrode layer is formed by powder molding using only an electrode active material, the electrolyte is solid, so that the electrolyte hardly penetrates into the electrode layer, and the electrode active material and the electrolyte Interface is reduced, and the battery performance is degraded. Therefore, the area of the interface is usually increased by forming an electrode layer using an electrode mixture containing a mixed powder obtained by mixing an electrode active material powder and an electrolyte powder.
According to the present invention, when a sulfide-based solid electrolyte material is used as an electrolyte in an electrode layer using such an electrode mixture, the sulfur component in the sulfide-based solid electrolyte material is bound as described above. By bonding with the double bond of the binder polymer, an electrode layer with improved lithium ion conductivity can be obtained by reducing the amount of binder polymer without reducing flexibility and workability. .
In the present invention, as described later, when a positive electrode active material is used as the electrode active material, a positive electrode layer can be obtained. Moreover, when a negative electrode active material is used as the electrode active material, a negative electrode layer can be obtained.

Specifically, the electrode layer can be obtained through the following steps.
For example, first, a sulfide-based solid electrolyte material mixed powder is obtained by the mechanical milling step. Next, a sulfide-based solid electrolyte material is obtained by the sulfide-based solid electrolyte material forming step.
Next, in the electrode layer forming slurry preparation step, the electrode active material, the sulfide-based solid electrolyte material, and the binder polymer having a double bond capable of binding to the sulfur component are mixed in a solvent, thereby A layered slurry is obtained.
In the bonding treatment step, after the electrode layer forming slurry is applied onto the substrate, the bonding treatment such as heat treatment is performed to evaporate the solvent, and the sulfur component in the sulfide solid electrolyte material and the above An electrode layer can be obtained by combining with a double bond of a binder polymer.

Such a method for producing an electrode layer of the present invention is not particularly limited as long as it is a production method having the electrode layer forming slurry preparation step and the bonding treatment step, and may have other steps. good.
Hereinafter, each process in the manufacturing method of the electrode layer of this invention is demonstrated in detail.

1. Electrode layer forming slurry preparation step The electrode layer forming slurry preparation step in the present invention is an electrode active material, a sulfide-based solid electrolyte material, and a binder polymer having a double bond capable of binding to a sulfur component in a solvent. This is a step of obtaining an electrode layer forming slurry by mixing in step (b).
By passing through this step, it is possible to obtain an electrode layer forming slurry that is used in the bonding treatment step described later.

The electrode active material used in this step is not particularly limited as long as it does not easily react with the sulfide-based solid electrolyte material.
Specifically, when the electrode active material is a positive electrode active material, TiS ₂ , MoS ₂ , FeS ₂ , CuS in the sulfide system, LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiFePO _4, etc. in the oxide system are used. Among them, LiCoO ₂ and LiFePO ₄ are preferable. This is because the reactivity with the sulfide-based solid electrolyte material is low and the stability is excellent.
Moreover, when an electrode active material is a negative electrode active material, carbon fiber, artificial graphite, natural graphite, coke, VGCF, metallic lithium, metallic indium, etc. are mentioned, Among these, carbon fiber and artificial graphite are preferable. This is because the reactivity with the sulfide-based solid electrolyte material is low and the stability is excellent.

The shape of the electrode active material is not particularly limited as long as it is a shape that can be mixed with the sulfide-based solid electrolyte material and the binder polymer, but is usually in the form of fine particles. The shape of the fine particles is preferably, for example, spherical or elliptical.
In the case where the electrode active material is fine particles, the average particle diameter can be, for example, 100 μm or less, preferably 0.1 to 20 μm, particularly preferably 1 to 10 μm.
In the present invention, the average particle diameter of the electrode active material may be a value measured based on image analysis using an electron microscope such as SEM.

The content of the electrode active material in the electrode layer is particularly limited as long as it is a content that can form an electrode layer capable of occluding and releasing sufficient lithium ions in a secondary battery. However, the content can be set to the same level as that of an electrode layer having a sulfide-based solid electrolyte material and an electrode active material, which is usually used for an all solid lithium secondary battery.
Specifically, the volume fraction of the electrode active material in the electrode layer is preferably 20 to 80 vol%.

  In this step, in addition to the electrode active material, sulfide-based solid electrolyte material, and binder polymer described above, a conductive material for improving conductivity, a surfactant, and the like are added to the solvent. It may be an electrode layer forming slurry.

  The conductive material is not particularly limited as long as it has a function as a conductive material, and the same conductive material as that used in a general all solid lithium secondary battery can be used. Examples thereof include acetylene black, ketjen black, and carbon fiber.

  The other details of this step are the same as those described in “A. Production Method of Solid Electrolyte Layer 1. Solid Electrolyte Layer Forming Slurry Preparation Step”, and therefore will be omitted.

2. Bonding treatment step The bonding treatment step in the present invention is a step of bonding the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer by bonding the electrode layer forming slurry. It is.

  By passing through this step, as described above, by combining the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer, without reducing flexibility and workability, The amount of the binder polymer can be reduced, and an electrode layer with improved lithium ion conductivity can be obtained.

In this step, the electrode layer-forming slurry is subjected to a bonding treatment. Usually, an electrode layer can be obtained by applying the electrode layer-forming slurry on a predetermined base material and performing the above-described bonding treatment. .
The base material used when performing such coating or the like is not particularly limited. For example, a metal foil having a current collector function, a peelable group such as a Teflon (registered trademark) sheet, and the like. Materials, generally used solid electrolyte layers, solid electrolyte layers obtained by the above-mentioned “A. Production method of solid electrolyte layers”, and the like can also be used.
When a peelable substrate such as the Teflon (registered trademark) sheet is used, the electrode layer can be obtained by peeling the electrode layer portion from the substrate.

  The other details of this step are the same as those described in “A. Manufacturing Method of Solid Electrolyte Layer 2. Coupling Treatment Step”, and are therefore omitted.

3. Other Steps In the present invention, in addition to the electrode layer forming slurry preparation step and the bonding treatment step, which are indispensable steps in the present invention, a bonding promoting sulfur-containing material addition step, a mechanical milling step, a sulfide-based solid electrolyte material You may have a formation process, a compacting process, etc.
The details of these other steps are the same as those described in “A. Method for producing solid electrolyte layer 3. Other steps”, and therefore description thereof is omitted.
In the present invention, the electrode active material may be added in advance during the mechanical milling step. Usually, in the electrode layer forming slurry preparation step described above, or in the electrode layer forming slurry preparation step. It is preferable to add later. It is because it can prevent that the performance of an electrode active material falls by mechanical milling. Moreover, when adding the said electrode active material after an electrode layer formation slurry preparation process, the mixing process for mixing the said electrode active material with an electrode layer formation slurry is normally performed after addition.

4). Others The electrode layer obtained by the production method of the present invention is useful, for example, as an electrode layer for an all solid-state lithium battery.

C. Manufacturing method of all-solid-state lithium secondary battery The manufacturing method of the all-solid-state lithium secondary battery of this invention is demonstrated in detail below.
The manufacturing method of the all-solid-state lithium secondary battery of the present invention was obtained by the solid electrolyte layer obtained by the above “A. manufacturing method of the solid electrolyte layer” or the above “B. manufacturing method of the electrode layer”. It is a manufacturing method characterized by having the battery element formation process which forms a battery element using at least one of an electrode layer.
According to the present invention, a solid electrolyte layer having an improved lithium ion conductivity by reducing the amount of binder polymer, or an electrode layer having an improved lithium ion conductivity by reducing the amount of binder polymer. By using at least one, an all-solid lithium secondary battery with improved battery performance can be obtained.
More specifically, the solid electrolyte layer obtained by the above-mentioned “A. Production method of solid electrolyte layer” is used as the solid electrolyte layer, and a general electrode layer usually used as an electrode layer is used. A battery element forming step to be formed (first embodiment), and an electrode layer obtained by the above-mentioned “B. Method for producing electrode layer” as an electrode layer, and usually as a solid electrolyte layer What has the battery element formation process which forms a battery element using the general solid electrolyte layer used (2nd embodiment), said "A. solid as a solid electrolyte layer and an electrode layer" It has a battery element formation process which forms a battery element using the solid electrolyte layer obtained by "the manufacturing method of an electrolyte layer", and the electrode layer obtained by said "B. manufacturing method of an electrode layer" characterized by the above-mentioned. Also It can be mentioned three embodiments of the (third embodiment).
Hereinafter, the method for producing the all solid lithium secondary battery of the present invention will be described in detail for each embodiment.

1. 1st embodiment The manufacturing method of the all-solid-state lithium secondary battery of this embodiment uses the solid electrolyte layer obtained by said "A. manufacturing method of a solid electrolyte layer" as said solid electrolyte layer, and is normally used as an electrode layer It has the battery element formation process which forms a battery element using the common electrode layer used.
According to this embodiment, an all-solid lithium secondary battery having improved lithium ion conductivity can be obtained.

In this embodiment, for example, first, in “A. Method for producing solid electrolyte layer”, a peelable substrate such as a Teflon (registered trademark) sheet is used as the substrate, and the substrate is formed on the substrate. When the solid electrolyte layer is obtained by removing the substrate from the solid electrolyte layer, the positive electrode layer is usually formed on the solid electrolyte layer, and the negative electrode layer is opposite to the other of the solid electrolyte layers, that is, the positive electrode layer. A battery element forming step of obtaining a battery element comprising a solid electrolyte layer, a positive electrode layer, and a negative electrode layer, a positive electrode current collector forming step of forming a positive electrode current collector on the positive electrode layer, and the negative electrode layer A negative electrode current collector forming step for forming a negative electrode current collector, a battery assembly step in which the battery element is sandwiched between the positive electrode current collector and the negative electrode current collector and inserted into a battery case or the like to form a battery Etc.
Moreover, in this embodiment, if an all-solid lithium secondary battery having a battery element formed using the solid electrolyte layer can be obtained, the above-described steps can be performed simultaneously or the order of the steps can be changed. Or may have other steps.

  Next, the all solid lithium secondary battery obtained by this embodiment will be described with reference to the drawings. FIG. 2 is a schematic cross-sectional view schematically showing an example of the all solid lithium secondary battery in the present embodiment. The all-solid lithium secondary battery shown in FIG. 2 includes a solid electrolyte layer 1 obtained by “A. Production method of solid electrolyte layer”, a positive electrode layer 2 sandwiching the solid electrolyte layer 1, and a negative electrode layer 3. A battery element 4, a positive electrode current collector 5 formed on the positive electrode layer 2, a negative electrode current collector 6 formed on the negative electrode layer 3, and a battery case 7 are arranged so as to cover them. It is what.

The manufacturing method of such an all-solid lithium secondary battery is not particularly limited as long as it is a manufacturing method having at least the battery element forming step described above. The positive electrode current collector forming step, the negative electrode current collector described above, and the like. You may have other processes, such as a body formation process and a battery assembly process.
Hereinafter, each process in the manufacturing method of the all-solid-state lithium secondary battery of this invention is demonstrated in detail.

(1) Battery Element Formation Step The battery element formation step in the present invention is a general method that is usually used as an electrode layer, using the solid electrolyte layer obtained by the above-mentioned “A. Production method of solid electrolyte layer” as the solid electrolyte layer. This is a step of forming a battery element using a typical electrode layer.

As the positive electrode material used for the positive electrode layer in this step, the same materials as those used for a general all solid lithium secondary battery can be used. Examples thereof include positive electrode active materials such as metal oxides containing Li, metal phosphides containing Li and oxygen, and metal borides containing Li and oxygen. Moreover, you may use what was used as the mixture for positive electrodes by mixing a positive electrode active material and the solid electrolyte material generally used.
Moreover, in order to improve electroconductivity as needed, you may contain conductive support agents, such as acetylene black, ketjen black, and carbon fiber.

Moreover, as a negative electrode material used for the said negative electrode layer in this process, the material similar to the material used for a general all-solid-state lithium secondary battery can be used. For example, a material composed of only a negative electrode material such as a metal foil having a function as a negative electrode, a negative electrode mixture by mixing a negative electrode active material (eg, graphite) and a commonly used solid electrolyte material, etc. Can be mentioned.
Moreover, in order to improve electroconductivity as needed, you may contain conductive support agents, such as acetylene black, ketjen black, and carbon fiber.

  As for a specific method for forming a battery element in this step, a general electrode usually used as an electrode layer using the solid electrolyte layer obtained by the above-mentioned “A. Production method of solid electrolyte layer” as the solid electrolyte layer. The method is not particularly limited as long as the method can form a battery element using a layer. For example, a battery element comprising a solid electrolyte layer, a positive electrode layer, and a negative electrode layer, wherein a positive electrode layer is formed on the solid electrolyte layer and a negative electrode layer is formed on the other side of the solid electrolyte layer, that is, on the side opposite to the positive electrode layer. The method of forming can be mentioned.

(2) Other steps In the present invention, in addition to the battery element forming step, which is an essential step of the present invention, usually, as described above, the positive electrode layer forming step, the negative electrode layer forming step, the positive electrode current collector Other processes such as a forming process, a negative electrode current collector forming process, and a battery assembling process are included.
Since these steps are the same as those in a general all solid lithium secondary battery, description thereof is omitted here.

Next, the positive electrode current collector, the negative electrode current collector, the battery case, etc. used in the other processes will be described.
The positive electrode current collector collects current from the positive electrode layer. The material of the positive electrode current collector is not particularly limited as long as it has conductivity, and examples thereof include aluminum, SUS, nickel, iron and titanium. Among them, aluminum and SUS are preferable. . Furthermore, the positive electrode current collector may be a dense current collector or a porous current collector.
The negative electrode current collector is a current collector for the negative electrode layer. The material for the negative electrode current collector is not particularly limited as long as it has electrical conductivity, and examples thereof include copper, stainless steel, nickel, and the like, among which copper is preferable. Furthermore, the negative electrode current collector may be a dense current collector or a porous current collector.
As the battery case, generally, a metal case is used, for example, a stainless steel case. Further, the battery case may have a current collector function. Specifically, a case where a battery case made of SUS (stainless steel) is prepared and a part of the battery case is used as a current collector can be exemplified.

2. Second Embodiment The method for producing an all-solid lithium secondary battery according to this embodiment uses the electrode layer obtained by the above “B. Method for producing electrode layer” as an electrode layer, and is generally used as a solid electrolyte layer. It has a battery element formation process which forms a battery element using a typical solid electrolyte layer.
According to this embodiment, an all-solid lithium secondary battery with improved battery performance can be obtained by using the electrode layer.

In this embodiment, for example, first, in “B. Method for producing electrode layer”, a solid electrolyte layer that is generally used is used as a base material, on one surface of the solid electrolyte layer. When the positive electrode layer is formed, the negative electrode layer is further formed on the other surface of the solid electrolyte layer by using “B. Electrode layer manufacturing method”, and the solid electrolyte layer, the positive electrode layer, and the negative electrode layer are formed. A battery element forming step for obtaining a battery element, a positive electrode current collector forming step for forming a positive electrode current collector on the positive electrode layer, a negative electrode current collector forming step for forming a negative electrode current collector on the negative electrode layer, and the battery A battery assembly process or the like in which an element is sandwiched between the positive electrode current collector and the negative electrode current collector and inserted into a battery case or the like.
In the present embodiment, at least one of the positive electrode layer and the negative electrode layer among the electrode layers may be an electrode layer obtained by the above-mentioned “B. Method for producing electrode layer”. For this reason, when the positive electrode layer is formed by “B. Electrode layer manufacturing method”, the negative electrode layer is formed by performing a negative electrode layer forming step of forming a negative electrode layer using a commonly used negative electrode material. May be. Further, when the negative electrode layer is formed by “B. Electrode layer manufacturing method”, the positive electrode layer is formed by performing a positive electrode layer forming step of forming a positive electrode layer using a commonly used positive electrode material. Also good.

  The solid electrolyte material used for the solid electrolyte layer used in this step is not particularly limited, and the same materials as those used for general all solid lithium secondary batteries can be used. For example, an oxide-based solid electrolyte, sulfide-based crystallized glass, thiolysicon, a chloride-based solid electrolyte, a fluoride-based solid electrolyte, and the like can be given.

  Other details are the same as those described in the above-mentioned “C. Manufacturing method of all-solid lithium secondary battery 1. First embodiment”, and thus the description thereof is omitted here.

3. Third Embodiment A manufacturing method of an all-solid lithium secondary battery according to the present embodiment includes a solid electrolyte layer obtained by the above-mentioned “A. Manufacturing method of solid electrolyte layer” as the solid electrolyte layer and the electrode layer, and the above “ It has a battery element formation process which forms a battery element using the electrode layer obtained by the "B. manufacturing method of an electrode layer".
According to this embodiment, by using the solid electrolyte layer and the electrode layer, the lithium ion conductivity is improved, whereby an all solid lithium secondary battery having excellent battery performance can be obtained.

  In this embodiment, for example, first, in “A. Method for producing solid electrolyte layer”, a peelable substrate such as a Teflon (registered trademark) sheet is used as the substrate, and the substrate is formed on the substrate. When the solid electrolyte layer is obtained by removing the base material from the solid electrolyte layer, a positive electrode layer is formed on one side of the solid electrolyte using “B. A battery element forming step of forming a negative electrode layer on the other surface of the solid electrolyte layer using “B. Method for producing electrode layer” to obtain a battery element comprising the solid electrolyte layer, the positive electrode layer, and the negative electrode layer, A positive electrode current collector forming step of forming a positive electrode current collector on the positive electrode layer, a negative electrode current collector forming step of forming a negative electrode current collector on the negative electrode layer, and the battery element comprising the positive electrode current collector and the negative electrode current collector. Insert the battery clamped between the battery and the battery case to make a battery. Having a battery assembly process or the like.

  For other details, those described in "C. Production method of all solid lithium secondary battery 1. First embodiment" and "C. Production method of all solid lithium secondary battery 2. Second embodiment" Since it is the same as that, description here is abbreviate | omitted.

4). Others The application of the all-solid lithium secondary battery obtained by the present invention is not particularly limited, and for example, it can be used as a lithium secondary battery for automobiles.
In addition, examples of the shape of the all solid lithium secondary battery obtained by the present invention include a coin type, a laminate type, a cylindrical type, and a square type. Among these, a square type and a laminate type are preferable, and a laminate type is particularly preferable.
In the present invention, the solid electrolyte layer and the electrode layer that are preferably the third embodiment are both obtained by “A. Method for producing solid electrolyte layer” and “B. Method for producing electrode layer”. This is because the all-solid lithium secondary battery with improved lithium ion conductivity can be obtained more effectively by using the obtained one.

D. Solid electrolyte layer The solid electrolyte layer of the present invention is described in detail below.
The solid electrolyte layer of the present invention includes at least a sulfide-based solid electrolyte material and a binder polymer having a double bond capable of binding to a sulfur component, and the sulfur component in the sulfide-based solid electrolyte material It has the site | part which has couple | bonded with the double bond of the said binder polymer.

  According to the present invention, by having a site where the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer are bonded, it is possible to bind without reducing flexibility and workability. The amount of the agent polymer can be reduced, and a solid electrolyte layer with improved lithium ion conductivity can be obtained.

Whether or not the solid electrolyte layer of the present invention has a site where the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer are bonded to each other is determined by infrared spectroscopy. This can be confirmed by measuring the amount of decrease in the heavy bond concentration.
In addition, as the amount of the site where the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer are bonded in the solid electrolyte layer, specifically, for example, by infrared spectroscopy , (-C = C-) It is preferable that the reduction rate before and after the bonding of the peak (peak near 1620 cm ^-1 ) indicating the double bond site concentration is in the range of 10 to 80%.

  The details of the solid electrolyte layer are the same as those described in the above-mentioned “A. Production method of solid electrolyte layer”, and thus the description thereof is omitted here.

E. Electrode Layer The electrode layer of the present invention will be described in detail below.
The electrode layer of the present invention has at least an electrode active material, a sulfide-based solid electrolyte material, and a binder polymer having a double bond capable of binding to a sulfur component, and the sulfide-based solid electrolyte material includes It has the site | part which the sulfur component of this and the double bond of the said binder polymer have couple | bonded.

  According to the present invention, the amount of the binder polymer can be reduced by having a site where the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer are bonded to each other. An electrode layer with improved lithium ion conductivity can be obtained.

  The details of the electrode layer are the same as those described in “B. Electrode layer manufacturing method” described above, and thus the description thereof is omitted here. Whether or not the solid electrolyte layer has a site where the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer are bonded, the sulfide-based solid in the solid electrolyte layer The amount of the site where the sulfur component in the electrolyte material and the double bond of the binder polymer are bonded is the same as that described in “D. Solid electrolyte layer” described above. Description of is omitted.

F. All-solid lithium secondary battery The all-solid lithium secondary battery of the present invention will be described in detail below.
The all solid lithium secondary battery of the present invention is characterized in that at least one of the solid electrolyte layer and the electrode layer is used.
According to the present invention, a solid electrolyte layer having an improved lithium ion conductivity by reducing the amount of binder polymer, or an electrode layer having an improved lithium ion conductivity by reducing the amount of binder polymer. By using at least one, an all-solid lithium secondary battery with improved performance as an all-solid lithium secondary battery can be obtained.
More specifically, the solid electrolyte layer described in “D. Solid electrolyte layer” described above is used as the solid electrolyte layer, and a general electrode layer is used as the electrode layer (first embodiment) ), An electrode layer described in the above “E. Electrode layer” as an electrode layer, and a general solid electrolyte layer as a solid electrolyte layer (second embodiment), and a solid A solid electrolyte layer described in “D. Solid electrolyte layer” and an electrode layer described in “E. Electrode layer” are used as the electrolyte layer and the electrode layer (third embodiment) ) And three embodiments.

  For details of the all-solid lithium secondary battery of each of the above embodiments, refer to the above-described “C. Production method of all-solid lithium secondary battery 1. First embodiment”, “C. Production method of all-solid lithium secondary battery”. Since it is the same as that described in “2. Second Embodiment” and “C. Manufacturing Method of All Solid Lithium Secondary Battery 3. Third Embodiment”, description thereof is omitted here.

  The use of the all-solid lithium secondary battery of the present invention is the same as that described in “C. Method for producing all-solid lithium secondary battery 4. Others” described above. Omitted.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

  Hereinafter, the present invention will be described in more detail with reference to examples.

  In the following examples and comparative examples, all operations were performed in an argon gas-filled glove box unless otherwise indicated. In addition, all materials used were vacuum-dried at 120 ° C. for 24 hours before use, and the solvent used was confirmed to have a water content of 10 ppm by molecular sieve.

[Example 1]
(Sulfide solid electrolyte material formation)
After premixing 7.0 g of lithium sulfide (manufactured by Mitsuwa Chemicals, purity 99.9%) and 3.0 g of diphosphorus pentasulfide (manufactured by Aldrich, purity 99%) in an agate mortar, dry mechanical milling at 300 rpm, 20 By mixing uniformly according to time conditions, a sulfide solid electrolyte material mixed powder was obtained. This was heat-treated at 290 ° C. for 2 hours to obtain a sulfide solid electrolyte material.
(Solid electrolyte layer formation)
Next, in order to prepare a solid electrolyte layer forming slurry, styrene-butadiene rubber (styrene block ratio 20%) having an unsaturated bond (double bond) in the molecule was selected as a binder polymer. After mixing this so that the weight ratio with the above-mentioned sulfide solid electrolyte material is 0.5: 99.5, this mixture is put into heptane so that the weight ratio with dehydrated heptane is 30:70. Dispersed to form a solid electrolyte layer forming slurry. After sufficiently stirring this, it was cast on a SUS foil with a gap of 100 μm using a 4-side applicator made by Dazai Machine, and cut into a size of about 1 cm ² after drying. This was held at 180 ° C. for 10 minutes to carry out a bonding treatment to bond the double bond of the binder polymer and the sulfur component of the sulfide solid electrolyte material, thereby increasing the binding force. Then, the solid electrolyte layer was obtained by compacting (40 kN / cm ² ) at a size of 1 cm ^{2 with} a dedicated jig.

[Example 2]
A solid electrolyte layer was obtained in the same manner as in Example 1 except that ethylene propylene rubber (propylene block ratio: 20%) was used as the binder polymer.

[Example 3]
A solid electrolyte layer was obtained in the same manner as in Example 1 except that polybutadiene rubber was used as the binder polymer.

[Example 4]
A solid electrolyte layer was obtained in the same manner as in Example 1 except that the bonding treatment was performed at 150 ° C. for 30 minutes.

[Example 5]
A solid electrolyte layer was obtained in the same manner as in Example 1 except that the bonding treatment was performed at 120 ° C. for 60 minutes.

[Example 6]
A solid electrolyte layer was obtained in the same manner as in Example 1 except that the bonding treatment was performed at 120 ° C. for 10 minutes.

[Example 7]
A solid electrolyte layer was obtained in the same manner as in Example 1 except that the bonding treatment was performed at 100 ° C. for 10 minutes.

[Example 8]
A solid electrolyte layer was obtained in the same manner as in Example 1 except that the bonding treatment was performed at 100 ° C. for 30 minutes.

[Example 9]
A solid electrolyte layer was obtained in the same manner as in Example 1 except that the bonding treatment was performed at 100 ° C. for 60 minutes.

[Comparative Example 1]
A solid electrolyte layer was obtained in the same manner as in Example 1 except that the bonding treatment was not performed.

[Comparative Example 2]
A solid electrolyte layer was obtained in the same manner as in Example 1 except that the weight ratio of styrene butadiene and the sulfide solid electrolyte material was 2:98, and that the bonding treatment was not performed.

[Evaluation]
(Lithium ion conductivity measurement)
Using the solid electrolyte layers obtained in Examples 1 to 9, Comparative Example 1 and Comparative Example 2, lithium ion conductivity was measured. As a measuring apparatus, a potentiostat manufactured by Solartron was used.
Further, in Example 1, the sulfide solid electrolyte material obtained by heat-treating the sulfide solid electrolyte material mixed powder at 290 ° C. for 2 hours is simply pressed into pellets to obtain a sulfide solid electrolyte material. The lithium ion conductivity of the solid electrolyte layer made of only was measured.
(Evaluation of film thickness, binding state, flexibility)
Using the solid electrolyte layers obtained in Examples 1 to 9, Comparative Example 1 and Comparative Example 2, the thickness of the solid electrolyte layer was measured, the binding state, and the flexibility were confirmed. FIG. 3 shows the appropriate crosslinking reaction conditions in the examples inferred from these results. In FIG. 3, those having a good binding state and sufficient flexibility are indicated by ◯, and those having a good binding state and sufficient flexibility are indicated by ×. Furthermore, the estimated range of appropriate reaction conditions is indicated by hatching.
(Sulfur component-binder polymer bond evaluation)
After extracting the binder polymer in the solid electrolyte layers obtained in Examples 1 to 3 and Comparative Example 1 with a solvent, C = C (1620 cm ⁻¹ ), S—C (748 cm) by IR spectroscopy. ^-1 ) peak intensity was measured. From the height of the obtained peak, the binder polymer in the solid electrolyte layer of Examples 1 to 3 with respect to the C = C double bond portion peak height in the binder polymer in the solid electrolyte layer of Comparative Example 1 The ratio of C = C double bond part peak height in was obtained. Furthermore, from the height of the obtained peak, the binder in the solid electrolyte layers of Examples 1 to 3 with respect to the peak height of the S—C cross-linking portion in the binder polymer in the solid electrolyte layer of Comparative Example 1. The ratio of the S—C cross-linking peak height in the polymer was determined. The obtained results are shown in Table 1.

As a result of the lithium ion conductivity measurement, the solid electrolyte layer made only of the sulfide solid electrolyte material simply compacted into a pellet was 1.20 × 10 ⁻³ S / cm (100 kHz). Moreover, in Example 1, it was 9.01 * 10 < ^-4 > S / cm and was about 75% of the lithium ion conductivity of the solid electrolyte layer which consists only of sulfide solid electrolyte materials. Moreover, in Example 2, it was 8.52 * 10 < ^-4 > S / cm and was about 70% of the lithium ion conductivity of the solid electrolyte layer which consists only of sulfide solid electrolyte materials. Moreover, in Example 3, it was 7.84 * 10 < ^-4 > S / cm and was about 65% of the lithium ion conductivity of the solid electrolyte layer which consists only of sulfide solid electrolyte materials. Moreover, in Example 4, it was 9.93x10 < ^-4 > S / cm and was about 80% of the lithium ion conductivity of the solid electrolyte layer which consists only of sulfide solid electrolyte materials. Moreover, in Example 5, it was 8.66 * 10 < ^-4 > S / cm and was about 80% of the lithium ion conductivity of the solid electrolyte layer which consists only of sulfide solid electrolyte materials. In Example 6-9, it was ^{8.01 × 10 -4 ~9.85 × 10 -4} S / cm. Moreover, in Comparative Example 1, it was 9.21 × 10 ⁻⁴ S / cm. Moreover, in the comparative example 2, it was 5.04 * 10 < ^-4 > S / cm and fell to about 42% of the lithium ion conductivity of the solid electrolyte layer which consists only of sulfide solid electrolyte material.

  As for the film thickness, from the results of film thickness measurement, as shown in FIG. 3, the binding state and flexibility were as follows. The solid electrolyte layer of Example 1 had a film thickness of 55 μm, and it was confirmed that it had a good binding state and sufficient flexibility. Moreover, the solid electrolyte layer of Example 2 was 123 micrometers in thickness, and it was confirmed that it has a favorable binding state and sufficient flexibility. Moreover, the solid electrolyte layer of Example 3 was 72 micrometers in thickness, and it was confirmed that it has a favorable binding state and sufficient flexibility. Moreover, the solid electrolyte layer of Example 4 was 109 micrometers in thickness, and it was confirmed that it has a favorable binding state and sufficient flexibility. Moreover, the solid electrolyte layer of Example 5 was 74 micrometers in thickness, and it was confirmed that it has a favorable binding state and sufficient flexibility. In addition, the solid electrolyte layers of Examples 6 to 9 have a film thickness of 88 to 152 μm, and both the binding force and the flexibility are insufficient, and the machine can be broken or detached only by bending the SUS foil. Only the desired strength was maintained. Moreover, the solid electrolyte layer of Comparative Example 1 had very poor flexibility, and cracks were generated after the lithium ion conductivity measurement. Further, the solid electrolyte layer of Comparative Example 2 had a film thickness of 42 μm, and it was confirmed that the solid electrolyte layer had a good binding state and sufficient flexibility.

Moreover, as shown in Table 1, when the peak height of Comparative Example 1 is ¹ , the S—C cross-linking peak (748 cm ⁻¹ ) part height ratio is 12.0 in Example 1, In Example 2, it is 9.5, and in Example 3, it is 10.1. In the example, the proportion of the S—C cross-linking portion is increased by performing the bonding treatment, and sulfur in the sulfide-based solid electrolyte material is increased. It was confirmed that the component and the double bond of the binder polymer were bonded.

  From the above results, in the examples, the binding agent without reducing the flexibility and workability by binding the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer. A solid electrolyte layer with improved lithium ion conductivity could be obtained by reducing the amount of polymer. It was also found that a desired solid electrolyte layer can be obtained more reliably by making the heat treatment conditions appropriate.

DESCRIPTION OF SYMBOLS 1 ... Solid electrolyte layer obtained by this invention 2 ... Positive electrode layer 3 ... Negative electrode layer 4 ... Battery element 5 ... Positive electrode collector 6 ... Negative electrode body 7 ... Battery case

Claims (14)

  A solid electrolyte layer forming slurry preparation step for obtaining a solid electrolyte layer forming slurry by mixing a sulfide-based solid electrolyte material and a binder polymer having a double bond capable of binding to a sulfur component in a solvent; and A solid electrolyte layer comprising a bonding treatment step of bonding a sulfur component in the sulfide-based solid electrolyte material and a double bond of the binder polymer by bonding the solid electrolyte layer forming slurry. Manufacturing method.   The method for producing a solid electrolyte layer according to claim 1, wherein the bonding treatment is a heat treatment.   The method for producing a solid electrolyte layer according to claim 2, wherein the temperature of the heat treatment is in a range of 100C to 200C.   The method for producing a solid electrolyte layer according to any one of claims 1 to 3, wherein the solvent is a fluorine-based solvent.   The method for producing a solid electrolyte layer according to any one of claims 1 to 4, further comprising a step of adding a bond promoting sulfur-containing material.   Electrode layer forming slurry preparation step for obtaining an electrode layer forming slurry by mixing an electrode active material, a sulfide-based solid electrolyte material, and a binder polymer having a double bond capable of binding to a sulfur component in a solvent And a bonding treatment step of bonding the sulfur component in the sulfide-based solid electrolyte material and the double bond of the binder polymer by bonding the electrode layer forming slurry. Layer manufacturing method.   The method for manufacturing an electrode layer according to claim 6, wherein the bonding treatment is a heat treatment.   The temperature of the said heat processing exists in the range of 100 to 200 degreeC, The manufacturing method of the electrode layer of Claim 7 characterized by the above-mentioned.   The method for producing an electrode layer according to any one of claims 6 to 8, wherein the solvent is a fluorine-based solvent.   The method for producing an electrode layer according to any one of claims 6 to 9, further comprising a step of adding a bond promoting sulfur-containing material.   A solid electrolyte layer obtained by the method for producing a solid electrolyte layer according to any one of claims 1 to 5, or an electrode according to any one of claims 6 to 10. A method for producing an all-solid-state lithium secondary battery, comprising: a battery element forming step of forming a battery element using at least one of electrode layers obtained by the layer producing method.   At least a sulfide-based solid electrolyte material and a binder polymer having a double bond capable of binding to a sulfur component, and the sulfur component in the sulfide-based solid electrolyte material and the binder polymer double A solid electrolyte layer characterized by having a portion to which a bond is bonded.   At least an electrode active material, a sulfide-based solid electrolyte material, and a binder polymer having a double bond capable of binding to a sulfur component, and the sulfur component in the sulfide-based solid electrolyte material and the binding An electrode layer having a site where a double bond of an agent polymer is bonded.   An all-solid lithium secondary battery using at least one of the solid electrolyte layer according to claim 12 or the electrode layer according to claim 13.

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