KR20180072944A - Method of manufacturing a solid electrolyte layer and anode composite layer containing a sulfide-based solid electrolyte and all-solid electrolyte cell comprising the same - Google Patents

Abstract

The present invention relates to a method for manufacturing a solid electrolyte layer and an anode composite layer comprising a sulfide-based solid electrolyte, and an all-solid battery comprising the same. The method comprises the steps of: preparing a sulfide-based solid electrolyte; manufacturing a slurry comprising the sulfide-based solid electrolyte and a binder; and drying and pressing the slurry to obtain a solid electrolyte layer and an anode composite layer. Accordingly, the binder can be mixed with the sulfide-based solid electrolyte to prevent the solid electrolyte from being broken by repeated shrinkage and expansion.

Description

TECHNICAL FIELD [0001] The present invention relates to a solid electrolyte layer comprising a sulfide-based solid electrolyte and a method for producing the same, the same}

The present invention relates to a solid electrolyte layer containing a sulfide-based solid electrolyte and a method for producing the same, and more particularly to a method for producing a solid electrolyte layer comprising a sulfide-based solid electrolyte and a binder, The present invention relates to a method for producing a solid electrolyte layer and a positive electrode composite layer containing a sulfide-based solid electrolyte capable of preventing breakage by repetition, and an all solid battery including the same.

The secondary battery has been mainly applied to a small-sized field such as a mobile device or a notebook computer. However, recently, the application of the secondary battery has been expanding into a medium- and large-sized field, and an energy storage system (ESS) And the like are being expanded to fields requiring high energy and high output. Unlike a small-sized and medium-sized secondary battery, operating environments such as temperature and impact are not only severe but also require a large number of batteries. Therefore, it is necessary to ensure safety with good performance and reasonable prices. Most commercialized secondary batteries use an organic liquid electrolyte in which a lithium salt is dissolved in an organic solvent, which poses a potential risk of ignition and explosion including leakage.

Therefore, all-solid-state batteries are being developed in recent years. Batteries using non-combustible inorganic solid electrolytes as compared with lithium secondary batteries using conventional combustible organic liquid electrolytes have a higher thermal stability Is high. The precharge cell generally has a laminated structure of an anode current collector layer, a cathode electrode composite layer, a solid electrolyte layer, a cathode electrode composite layer, and a cathode collector layer. Examples of suitable processes for mass production of such prior solid-state batteries include 'Slurry, a method for producing a solid electrolyte layer, a method for producing an electrode active material layer, and a method for manufacturing an all-solid battery', Korean Registered Patent No. 10-1506833 A technique of the same slurry application method is being developed.

The solid electrolyte has an oxide system and a sulfide system. However, since the oxide-based solid electrolyte has a high heat treatment temperature of 400 ° C or more, and thus the electrode and the electrolyte layer can not be heat-treated after the production, Materials are used. When a sulfide-based solid electrolyte is used as a solid electrolyte material, a heat treatment process must be performed to obtain a material having a high ion conductivity. Accordingly, the prior art processes include preparing a slurry containing a crystalline or glass-ceramic sulfide-based solid electrolyte material prepared through a heat treatment process, and forming a coating film for forming a solid electrolyte layer with the slurry And drying the solid electrolyte layer by drying the coating film.

However, such a solid electrolyte has a problem in that when the lithium ion is charged and discharged into the solid electrolyte, the solid electrolyte repeatedly shrinks and expands and is broken.

Korea Intellectual Property Office Registration No. 10-1506833 Korea Patent Office Registration No. 10-1460113 Korean Patent Application Publication No. 10-2014-0073400

Accordingly, an object of the present invention is to provide a method for producing a solid electrolyte layer and a positive electrode composite layer comprising a sulfide-based solid electrolyte capable of mixing a binder with a sulfide-based solid electrolyte to prevent the solid electrolyte from being broken by shrinkage and expansion repeatedly, and The present invention also provides a solid-state battery comprising the same.

The above-mentioned object is achieved by a method of manufacturing a semiconductor device, comprising: preparing a sulfide-based solid electrolyte; Preparing a slurry comprising the sulfide-based solid electrolyte and a binder; And a step of drying and pressing the slurry to obtain a solid electrolyte layer and a positive electrode composite layer. The solid electrolyte layer and the positive electrode composite layer manufacturing method according to the present invention include a sulfide-based solid electrolyte.

Here, the binder is selected from the group consisting of polystyrene, polystyrene nitrile-butadiene rubber (PS-NBR), poly (methacrylate) nitrile-butadiene rubber (PSB), and mixtures thereof, It is preferable that 0.1 to 10 wt% of the total 100 wt% is included.

The step of drying and pressing the slurry to obtain a solid electrolyte layer or a positive electrode composite layer may be performed by applying the slurry to a current collector, followed by drying and pressing to obtain the solid electrolyte layer and the positive electrode composite layer, Drying and pressing to obtain a solid electrolyte layer or a positive electrode composite layer comprises drying the slurry to prepare a multi-particle cluster, and densifying the multi-particle cluster through heating and pressing to produce a pellet, It is preferable to obtain the electrolyte layer and the positive electrode composite layer.

The multi-particle clusters are prepared in the form of particles through spray drying or stirring and drying of the slurry, the slurry comprising: a solid electrolyte slurry comprising the sulfide-based solid electrolyte and a binder; Wherein the solid electrolyte layer is prepared through the solid electrolyte slurry, and the positive electrode composite layer is produced through the positive electrode composite slurry, wherein the positive electrode composite slurry is prepared by mixing the positive electrode composite slurry and the positive electrode composite slurry, wherein the positive electrode composite slurry contains the sulfide-based solid electrolyte, the binder, the conductive material and the positive electrode active material. desirable.

The above-described object is also achieved by a method of manufacturing a semiconductor device, A positive electrode composite layer formed on the current collector and including amorphous, crystalline or amorphous-crystalline sulfide-based solid electrolyte having a size of 0.1 to 10 탆, a binder, a conductive material, and an active material; And a solid electrolyte layer stacked on the positive electrode composite layer and including a sulfide-based solid electrolyte having a size of 0.1 to 10 탆 and a binder.

According to the above-described constitution of the present invention, a binder is mixed with the sulfide-based solid electrolyte to obtain the effect of preventing the solid electrolyte from being broken by shrinkage and expansion and repetition.

FIG. 1 is a flowchart of a method for producing a solid electrolyte layer and a positive electrode composite layer according to an embodiment of the present invention,
FIG. 2 is a graph showing the battery operation of all solid-state batteries according to the kind of the binder,
FIG. 3 is a SEM photograph showing the pore change according to the pressure of the NCM ₆₂₂ anode molding,
FIG. 4 is a graph comparing the particle size of the amorphous LSPS powder according to amorphous and crystallization.

Hereinafter, a solid electrolyte layer including a sulfide-based solid electrolyte according to the present invention, a method for producing the anode composite layer, and a pre-solid battery including the same will be described in detail with reference to the drawings.

A secondary battery of the present invention includes a current collector and a positive electrode composite layer formed on the current collector and including amorphous, crystalline or amorphous-crystalline sulfide-based solid electrolyte having a size of 0.1 to 10 탆, a binder, , And a solid electrolyte layer stacked on top of the positive electrode composite layer and including a sulfide-based solid electrolyte having a size of 0.1 to 10 mu m and a binder. In addition, a negative electrode composite layer may be further included, and a collector body laminated with the collector-positive electrode composite layer-solid electrolyte layer-negative electrode composite layer-collector may be obtained. Wherein the binder is selected from the group consisting of polystyrene, PS-NBS, PMMA-NBS and mixtures thereof.

As a method of manufacturing the solid electrolyte layer and the positive electrode composite layer, a sulfide-based solid electrolyte is first prepared as shown in FIG. 1 (S1).

An amorphous, crystalline or amorphous-crystalline LSPS (Li ₂ SP ₂ S ₅ ) solid electrolyte is prepared. A solid electrolyte is prepared by dry milling or wet milling of Li ₂ S and P ₂ S ₅ as raw materials for a solid electrolyte and pulverized to obtain a small diameter. A method for producing a solid electrolyte from a raw material of a solid electrolyte and a step for pulverizing and pulverizing the solid electrolyte to mix the zirconia ball with a solid electrolyte is preferably followed by a manufacturing and grinding process by rotating the zirconia ball. But is not limited to.

Here, the solid electrolyte can be selected from amorphous, crystalline, or amorphous-crystalline. In the case of amorphous, the solid electrolyte layer has a small diameter because it is made of particles having a diameter smaller than that of the crystalline material. In the case of a crystalline solid electrolyte, The particle diameter is large but the conductivity is excellent. Therefore, an amorphous, crystalline, or amorphous-crystalline solid electrolyte can be selected depending on the use of the whole solid battery.

To prepare a slurry containing a sulfide-based solid electrolyte (S2).

The slurry is prepared by mixing a binder, a conductive material and a solvent together with the amorphous, crystalline or amorphous-crystalline sulfide-based solid electrolyte obtained through the step S1. In the case of the solid electrolyte slurry constituting the solid electrolyte layer, it is composed of a sulfide-based solid electrolyte, a binder and a solvent. In the case of the anode composite slurry, the anode active material, the sulfide-based solid electrolyte, the binder and the solvent may be added with a conductive material . Here, the cathode active material may be an active material used in an ordinary secondary battery, or may be any surface-treated active material to reduce chemical reactivity with a sulfide-based solid electrolyte.

The binder may be applied to both the solid electrolyte slurry and the anode composite slurry, and the binder may be a polyamide-imide (PAI), a polyimide (PI), a polyamide (PA), a polyamic polyvinylidene fluoride (PVDF), polyvinylidene fluoride (PVDF-HFP), polyvinylidene fluoride (PVDF), polyethylene oxide (PEO) butadiene rubber, poly (vinylidene fluoride-co-hexafluoropropylene), nitrile-butadiene rubber (NBR), polystyrene nitrile-butadiene rubber (PS-NBR), poly (methacrylate) nitrile- Polystyrene, PS-NBR and PMMA-NBR are used as the most suitable binders, whereas polystyrene or PMMA is a relatively hard material, whereas NBR is a soft elastoplastic material, For use with In some it can be a mixture of these at an appropriate ratio to form a binder.

Such a binder is preferably contained in an amount of 0.1 to 10% by weight based on 100% by weight of the solid electrolyte slurry or the anode composite slurry. When the binder is less than 0.1% by weight, the solid electrolyte may repeatedly shrink and expand due to charge and discharge of lithium ions, and may break. On the other hand, when the amount is more than 10% by weight, the amount of the solid electrolyte to be added is decreased by the amount of the binder, thereby reducing the charge / discharge performance.

The solvent in which the binder is dissolved and the solid electrolyte and the binder are mixed uniformly is selected from the group consisting of toluene, xylene, dodecane, butylbutyrate and mixtures thereof in which the binder is dissolved But it is not limited thereto.

In addition, the conductive material contained in the anode composite slurry may be an active carbon, a carbon nanotube, a carbon fiber, a graphene, a graphite, a carbon black, , Acetylene black, ketjen black (KR), super P, metal nanowires, metal nano powders, and mixtures thereof.

bookbinder wt% SSE menstruum Ball milling (rpm) Coating property PS One ○ Xylene 150






○ NBR One ○ Toluene or
Xylene



△ PS-NBR
(4wt% -6wt%)
0.5 ○ ○ One ○ ○ 2 ○ △ PMMA-NBR

0.5 ○ ○ 2 ○ × 0.5 ○ △ PEPMNB


One ○ Dodecaine


×


○ 2 ○ ○ 3 ○ ○ 5 ○ ○ PVDF-HFP 3 ○ BBR ball-milled pdr ○

bookbinder wt% SSE menstruum Coating property PVDF 5 × NMP ○ PVDF-HFP 3 ○ BBR ○ PAI 5 × NMP
○ PEO 10 ○ - PTFE 2 × water - NBR One ○ Toluene or xylene





○ PS One ○ ○ PS-NBR
(4wt% -6wt%)

0.5 ○ △ One ○ ○ 2 ○ ○ PMMA-NBR
0.5 ○ △ 2 ○ ○ PEPMNB




0.5 ○ Dodecaine



× One ○ △ 2 ○ ○ 3 ○ ○ 5 ○ ○ 3 ○ BBR ○

Table 1 shows the coating properties of a solid electrolyte slurry mixed with a sulfide-based solid electrolyte (SSE) and a binder. The balance, except for the content of the binder in 100 wt%, is SSE, . As can be seen from the table, even if the binder is added, it can be confirmed that the coating is smooth without affecting the coating property. Table 2 shows the coating properties of the positive electrode composite slurry containing the NCM ₆₂₂ positive electrode active material together with the solid electrolyte and the binder. Table 2 As in Table 1, even when the binder is added, most of the binders do not affect the coating properties Can be confirmed.

The slurry is applied to the current collector, followed by drying and pressing to obtain a solid electrolyte layer or a positive electrode composite layer (S3).

The positive electrode composite slurry is applied to a current collector, dried and compressed to form an electrode composite layer having a high structural density, and a solid electrolyte slurry is coated on the positive electrode composite layer, followed by pressing to form a solid electrolyte layer. Here, the solid electrolyte layer and the positive electrode composite layer need not be subjected to a separate heat treatment, but the lithium ion conductivity may be increased by performing heat treatment at 50 to 300 ° C as needed.

That is, applying a positive electrode composite slurry or a solid electrolyte slurry, followed by drying, sealing, compression-structure densification, and improving the ion conductivity of the solid electrolyte. As a method of applying the slurry, it is preferable to use a Dr. blade method.

The multi-particle clusters are pressed to obtain a solid electrolyte layer or a positive electrode composite layer (S3 ').

In some cases, it is possible to carry out a step of preparing a multiparticulate cluster other than a method of applying a slurry to a current collector, followed by drying and pressing. The multiparticulate clusters are prepared in the form of particles by spray drying or stirring drying, and in the case of the drying step it is preferred to work in a vacuum or inert atmosphere at 50-150 ° C. And then the produced clusters may be densified by heating and pressing to produce pellets or sheets. At this time, the densification of the cluster is preferably carried out by pressing at a pressure of 10 to 500 MPa to produce a pellet. Such a pellet can be formed as a solid electrolyte layer or a positive electrode composite layer without preparing a separate current collector and then applying it to the current collector.

Hereinafter, embodiments of the present invention will be described in more detail.

<Examples>

Li ₂ S and P ₂ S ₅ powders were quantitatively measured in order to obtain an amorphous LSPS (Li ₂ SP ₂ S ₅ ) solid electrolyte and placed in a 250 ml ball mill reaction vessel. A 5 mm diameter zirconia ball Put 200g and 60g of 2mm zirconia balls together. Then, LSPS solid electrolyte powder was obtained by performing high energy dry ball milling at 400 rpm for 20 hours (net time). At this time, in order to prevent the excessive rise of the temperature of the reaction vessel, the reaction was performed for 30 minutes and then the reaction was stopped for 20 minutes.

In order to reduce the particle size of the obtained amorphous solid electrolyte, a solid electrolytic pulverization process is performed. In order to pulverize the solid electrolyte, 2 g of the amorphous solid electrolyte is mixed with 16 ml of heptane, 2 g of dibutyl ether, 60 g of zirconia balls and 20 g of a 0.1 mm-diameter zirconia balls were ball-milled at 150 rpm for 10 hours to finely crush the amorphous solid electrolyte particles. The obtained amorphous solid electrolyte powder was recovered, washed, separated with liquid, vacuum dried at room temperature and vacuum dried at 120 ° C to obtain a pure amorphous solid electrolyte powder.

The procedure of manufacturing the all-solid-state battery test cell using the amorphous solid electrolyte powder produced in this way is as follows. First, a positive electrode composite layer is LiZrO ₃ or LiNbO _3, and the thickness of ~ 10nm _{LiNi 0 .6 Mn 0 .2 Co 0} .2 O 2 positive active material coated with the solid electrolyte is an amorphous LSPS, super conductive material P or VGCF, binder PS or PS-NBR is used to prepare a slurry in which xylene is mixed at a weight ratio of 67.2: 28.8: 2: 2.

The slurry was then applied to an aluminum current collector, dried and compressed to produce a positive electrode composite layer. Then, the solid electrolyte layer was prepared by applying a slurry in which amorphous LSPS and binder were dispersed at the upper part of the positive electrode composite layer, followed by vacuum drying at 80 DEG C for 12 hours. The thus prepared positive electrode composite layer / solid electrolyte layer was simultaneously pressed at a pressure of 200 to 350 MPa, and then an experimental cell was prepared as an indium counter electrode. The test cell is composed of a positive electrode composite layer / solid electrolyte layer / indium (In) counter electrode, and specifically, a positive electrode composite layer / Li ₂ SP ₂ S ₅ containing LSPS sulfide solid electrolyte, LiZrO ₂ -coated NCM ₆₂₂ , It is an experimental cell composed of a solid electrolyte layer / indium counter electrode including a sulfide-based solid electrolyte and a binder. Here, the sulfide-based solid electrolyte is an amorphous solid electrolyte of LSPS (80Li ₂ S-20P ₂ S ₅ , 75Li ₂ S-25P ₂ S _5, etc., for example, Li ₇ P ₃ S ₁₁ ) . At this time, all solid-state batteries are manufactured by using a negative electrode composite layer or an indium / lithium-lithium metal alloy electrode prepared by mixing a negative electrode active material for a lithium-ion battery such as graphite in place of the indium counter electrode as a counter electrode with a solid electrolyte in the same manner as the positive electrode composite .

FIG. 2 is a graph showing the battery operation of all solid-state batteries according to the types of binders. It can be confirmed that even when a positive electrode composite layer and a solid electrolyte layer are produced by adding a binder, there is no abnormality in charging / discharging performance.

FIG. 3 is a SEM photograph showing the pore change according to the pressure of the NCM ₆₂₂ positive electrode mold-formed body. FIGS. 3a and 3b show amorphous solid electrolytes, and FIGS. 3a-1 and b-1 show crystalline solid electrolytes. At 225 MPa pressure, the pores are distributed a little more and the pores between the cathode material and the particles are the space where the solid electrolyte, the conductive material and the binder can exist. When the pressure is 450 MPa, the pores existing between the cathode material particles are narrow and the amount thereof is considerably reduced, thereby forming a space in which the cathode material, the conductive material, and the binder are thinly present.

FIG. 4 is a graph comparing the particle size of amorphous LSPS powders prepared by a wet ball milling reaction and their crystalline powders in a mixed solvent of dibutyl ether and heptane to determine amorphous and crystalline states. As a result, it can be confirmed that the amorphous LSPS powder has a particle size of 0.1 to 10 mu m, which is smaller than that of the crystalline LPSI powder.

Crystalline state of LSPS d (0.1) d (0.5) d (0.9) Crystalline (~ 10-3 S / cm) after LSPS milling 19.817 m 25.393 탆 30.452 탆 Amorphous (~ 10-3 S / cm) after LSPS milling 0.702 탆 3.349 탆 5.979 탆

Table 3 shows that the LSPS of crystalline and amorphous materials differ not only in the degree of lithium ion conductivity but also in the particle size after the milling process. For example, the d (0.5) grain size is about eight times as great as that of crystalline and amorphous. Therefore, in producing the solid electrolyte layer and the positive electrode composite layer, it is advantageous to use an amorphous solid electrolyte having a smaller particle size than a crystalline or amorphous-crystalline solid electrolyte to obtain a uniform mixed electrode. The amorphous particles having a small particle size also minimize pores when pressing the solid electrolyte layer or the electrode composite layer and help maximize the contact between the solid electrolyte layer and the constituent materials of the electrode composite layer.

When a solid electrolyte layer and a positive electrode composite layer are manufactured by applying the same to a full solid battery, a binder is mixed with a sulfide-based solid electrolyte to prevent the solid electrolyte from being broken by shrinkage and expansion repeatedly have.

Claims (8)

A solid electrolyte layer comprising a sulfide-based solid electrolyte and a method for producing a positive electrode composite layer,
Preparing a sulfide-based solid electrolyte;
Preparing a slurry comprising the sulfide-based solid electrolyte and a binder;
And drying and pressing the slurry to obtain a solid electrolyte layer and a positive electrode composite layer. The method for producing a solid electrolyte layer and a positive electrode composite layer according to claim 1, The method according to claim 1,
Wherein the binder is selected from the group consisting of polystyrene (PS), polystyrene nitrile-butadiene rubber (PS-NBR), poly (methacrylate) nitrile-butadiene rubber A solid electrolyte layer comprising a solid electrolyte and a method for producing a positive electrode composite layer. The method according to claim 1,
Wherein the binder comprises 0.1 to 10% by weight of 100% by weight of the whole slurry. The method according to claim 1,
Wherein the step of drying and compressing the slurry to obtain a solid electrolyte layer or a positive electrode composite layer comprises applying the slurry to a current collector, followed by drying and pressing to obtain the solid electrolyte layer or the positive electrode composite layer A method for producing a solid electrolyte layer and a positive electrode composite layer containing an electrolyte. The method according to claim 1,
The step of drying and pressing the slurry to obtain a solid electrolyte layer or a positive electrode composite layer may include drying the slurry to prepare a multi-particle cluster, densifying the multi-particle cluster through heating and pressing to form a pellet or a sheet wherein the solid electrolyte layer or the positive electrode composite layer is produced in the form of a sheet and a solid electrolyte layer and a positive electrode composite layer. 6. The method of claim 5,
Wherein the multi-particle clusters are prepared in the form of particles through spray drying or stirring and drying of the slurry. The method according to claim 1,
The slurry,
A solid electrolyte slurry comprising the sulfide-based solid electrolyte and a binder;
And a positive electrode composite slurry including the sulfide-based solid electrolyte, a binder, a conductive material, and a positive electrode active material,
Wherein the solid electrolyte layer is produced through the solid electrolyte slurry and the positive electrode composite layer is produced through the positive electrode composite slurry. In all solid state batteries,
The whole house;
A positive electrode composite layer formed on the current collector and including amorphous, crystalline or amorphous-crystalline sulfide-based solid electrolyte having a size of 0.1 to 10 탆, a binder, a conductive material, and an active material;
And a solid electrolyte layer stacked on the positive electrode composite layer and including a sulfide-based solid electrolyte having a size of 0.1 to 10 탆 and a binder.

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