KR102684867B1 - Method for producing solid electrolyte membrane with reinforcement factor and solid electrolyte membrane produced from the same, and all-solid-state battery including the same - Google Patents

Abstract

The present invention relates to a method for manufacturing a solid electrolyte membrane using a reinforcing factor, a solid electrolyte membrane manufactured therefrom, and an all-solid-state battery containing the same. More specifically, the present invention relates to a method for manufacturing a solid electrolyte membrane using a reinforcing factor, and more specifically, to a method for manufacturing a solid electrolyte membrane using a reinforcing factor. The present invention relates to an all-solid-state battery with excellent mechanical strength by preventing damage from shock, contraction, and expansion by manufacturing a solid electrolyte membrane in the form of a sheet or free form.
The present invention provides a method for manufacturing a solid electrolyte membrane using a reinforcing factor, which is formed by comprising a reinforcing factor in the form of a fiber or tube and a sulfide-based solid electrolyte, and a solid electrolyte manufactured therefrom. The technical point is a membrane and an all-solid-state battery containing it.

Description

Method for producing solid electrolyte membrane with reinforcement factor and solid electrolyte membrane produced from the same, and all-solid-state battery including the same}

The present invention relates to a method for manufacturing a solid electrolyte membrane using a reinforcing factor, a solid electrolyte membrane manufactured therefrom, and an all-solid-state battery containing the same. More specifically, the present invention relates to a method for manufacturing a solid electrolyte membrane using a reinforcing factor, and more specifically, to a method for manufacturing a solid electrolyte membrane using a reinforcing factor. The present invention relates to an all-solid-state battery with excellent mechanical strength by preventing damage from shock, contraction, and expansion by manufacturing a solid electrolyte membrane in the form of a sheet or free form.

In general, lithium-ion secondary batteries are gradually expanding from small-sized fields such as mobile devices, laptops, and computers to medium- to large-sized fields, such as energy storage systems (ESS) or electric vehicles (EV).

In these fields, high output and high energy are required, and above all, secondary batteries that are safe for humans are needed.

However, most currently commercialized secondary batteries use an organic liquid electrolyte in which lithium salt is dissolved in an organic solvent, so they have the potential risk of leakage, ignition, and explosion.

Therefore, in recent years, all-solid-state batteries have been developed. All-solid-state batteries are batteries that use a non-flammable inorganic solid electrolyte and have lower thermal energy compared to lithium-ion secondary batteries that use a conventional flammable organic liquid electrolyte. It has the advantage of high stability.

Typically, an all-solid-state battery has a structure in which a negative electrode current collector layer, a negative electrode composite layer, a solid electrolyte layer, a positive electrode composite layer, and a positive electrode current collector layer are stacked. Among the prior technologies for these all-solid-state batteries, processes suitable for mass production include 'slurry, solid electrolyte layer manufacturing method, electrode active material layer manufacturing method, and all-solid-state battery manufacturing method (registration number: 10-1506833)'. Slurry application technology is being developed.

At this time, solid electrolytes are of oxide type and sulfide type. In the case of oxide-based solid electrolytes, the heat treatment temperature is as high as 400°C or higher, making heat treatment impossible after manufacturing the electrode and electrolyte layer. In the case of sulfide-based solid electrolytes, when using solid electrolyte materials, the thickness of the large-area membrane must be thin and the resistance inside the battery must be low to further increase the practicality of the large-area all-solid-state battery.

However, the ceramic solid electrolyte alone must be thick (e.g., t=500㎛) so that defects such as cracks are less likely to occur and an all-solid-state battery can be formed. For this reason, it is difficult to manufacture a large-area all-solid-state battery in the form of a membrane as described above, and various methods are being attempted.

Examples include a method of coating the surface of an electrode through slurry mixing a solid electrolyte with a solvent and a binder, or a method of preparing a porous film and impregnating it with a solid electrolyte.

However, as the amount of binder increases, ionic conductivity decreases, impregnation is unlikely to occur when non-woven fabric is used, and there are problems with the presence of partial cracks or ionic non-conductor areas during compression.

In addition, integral polymer non-woven fabrics or porous materials have problems in that they are not free in their shape and tend to detach/separate due to their large elongation during high compression, pressing, or rolling. Therefore, technology development research to improve this is urgently needed. am.

Domestic Patent Publication No. 10-1506833, registered on March 23, 2015.

The present invention was invented to solve the above problems, and by mixing a sulfide-based solid electrolyte and a reinforcement factor to manufacture a sheet-shaped solid electrolyte membrane, preventing damage due to impact, contraction, and expansion. The purpose of the present invention is to provide a method for manufacturing a solid electrolyte membrane using a reinforcing factor that improves mechanical strength, a solid electrolyte membrane manufactured therefrom, and an all-solid-state battery containing the same.

The present invention for achieving the above object includes a first step of preparing a reinforcing factor in the form of a fiber or tube; And a second step of mixing the reinforcing factor with a sulfide-based solid electrolyte and then spreading it uniformly to a certain thickness or pressing and molding it into a certain shape. Make it to the point.

Preferably, the reinforcing factor in the first step is at least one of polyimide (PI), polyamide (PAI), and polyvinylidene fluoride (PVDF).

Preferably, in the second step, dry mixing is performed when the sulfide-based solid electrolyte is in particle form, and wet mixing is performed when the sulfide-based solid electrolyte is in liquid form.

Preferably, in the second step, 1 to 99% by volume of the reinforcing factor and 1 to 99% by volume of the sulfide-based solid electrolyte are mixed.

Meanwhile, the present invention for achieving the above object includes a reinforcing element in the form of a fiber or tube; The technical gist is a solid electrolyte membrane using a reinforcing factor, which is formed including a sulfide-based solid electrolyte.

Preferably, the reinforcing factor is at least one of polyimide (PI), polyamide (PAI), and polyvinylidene fluoride (PVDF).

Preferably, the reinforcing factor comprises 0.5 to 99% by volume relative to the total volume of the solid electrolyte membrane.

On the other hand, the present invention for achieving the above object, an anode; cathode; and a solid electrolyte membrane formed between the anode and the cathode and formed by mixing a reinforcing element in the form of a fiber or tube and a sulfide-based solid electrolyte. A reinforcing element comprising a. The technical point is an all-solid-state battery including a solid electrolyte membrane.

The method for manufacturing a solid electrolyte membrane using a reinforcing factor according to the present invention as a means of solving the above problem, the solid electrolyte membrane manufactured therefrom, and the all-solid-state battery including the same have the following effects.

First, in a wet method, a slurry is created by mixing a reinforcement factor with a sulfide-based solid electrolyte and combined with a support that supports the slurry, or in a dry method, the sulfide-based solid electrolyte particles and reinforcement factors are mixed and spread uniformly or in a defined area. By increasing mechanical flexibility by manufacturing it in the form of a thin sheet manufactured by pressing with a shaped mold or applying pressure by rolling, it maintains the mechanical strength of the sulfide-based solid electrolyte and is suitable for the large-area all-solid-state battery manufacturing process. It has the effect of suggesting a process that makes it possible to manufacture area membranes.

Second, there is an effect of preventing the all-solid-state battery including the membrane obtained as described above from breaking due to repeated impact, contraction, and expansion.

1 is an illustration of a solid electrolyte membrane according to a preferred embodiment of the present invention.
Figure 2 is a photograph of a membrane according to a preferred embodiment of the present invention.
Figure 3 is a table according to Figure 2.
Figure 4 is a graph according to Figure 3.
Figure 5 is a photograph of a membrane according to a preferred embodiment of the present invention.
Figure 6 is a table according to Figure 5.
Figure 7 is a graph according to Figure 6.

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is an exemplary diagram of a solid electrolyte membrane according to a preferred embodiment of the present invention. Referring to FIG. 1, the solid electrolyte membrane using the reinforcing factor 200 of the present invention has a sulfide-based solid electrolyte 100 mixed with the reinforcing factor 200 and press-molded into a pellet or sheet shape. can confirm.

This solid electrolyte membrane includes the first step (S1) of preparing a reinforcing factor (200) in the form of a fiber or tube, and mixing the reinforcing factor (200) with the sulfide-based solid electrolyte (100) at a certain level. It can be manufactured through the second step (S2) of compression molding into a shape, and the first step (S1) and second step (S2) will be described in more detail below.

First, the first step is to prepare a reinforcing element 200 in the form of a fiber or tube. (S1)

First, the reinforcing factor 200 is an electronic insulator, but may be an ionic conductor complexed or hybridized with a lithium salt.

Since this reinforcing factor (200) exists in a discontinuous state when mixed with the sulfide-based solid electrolyte (100), it plays a role in holding particles together, and may have the form of a polymer fiber, ceramic fiber, or tube, etc., and may be a matrix. Any form that can compensate for mechanical defects or ion conduction defects that may occur in the phosphorus sulfide-based solid electrolyte area can be applied.

In the present invention, it is suggested that the reinforcing factor 200 may be one or more of polyimide (PI), polyamide (PAI), and polyvinylidene fluoride (PVDF), but only the above types. It is not limited, and any material that can stably provide mechanical strength to the sulfide-based solid electrolyte can be applied.

Here, if the reinforcement factor (200) is less than 1 nm, excellent mechanical strength cannot be provided to the sulfide-based solid electrolyte, and if it exceeds 200㎛, the miscibility with the sulfide-based solid electrolyte (100) is poor, resulting in a flat solid electrolyte membrane. Since it becomes difficult to obtain, it is recommended that the strengthening factor 200 have a size of 1 nm to 200 ㎛, but regardless of the shape, it can increase the macroscopic strength of the sulfide-based solid electrolyte or prevent defects such as cracks in the sulfide-based solid electrolyte. If it has a fine structure, it can be applied in a variety of ways.

Additionally, in some cases, it is possible to add an ionic conductive additive in the form of an ionic salt to the reinforcing factor 200.

Next, the second step is a step of mixing the strengthening factor 200 with the sulfide-based solid electrolyte 100 and then pressing and molding it into a certain shape. (S2)

In detail, the second step can be divided into a dry process and a wet process. If the sulfide-based solid electrolyte (100) is in particle form, a dry process is performed by dry mixing, and if the sulfide-based solid electrolyte (100) is in liquid form, the second step can be divided into a dry process and a wet process. It can be said to be wet mixing.

First, in the case of a dry process, the sulfide-based solid electrolyte particles are mixed with the reinforcing agent 200 in a dry manner, and then the mixed powder or cluster is spread evenly or spread evenly on a mold of a certain shape, and then molded with a press or roller. This is a method of manufacturing a pellet-shaped solid electrolyte membrane.

When dry mixed, the sulfide-based solid electrolyte particles can have a size of 0.001 to 100㎛. According to experimental results, if the particle size is less than 0.001㎛, the size is too small during the process and scattering occurs frequently, and if it exceeds 100㎛, the particle size is too small. This is because if the particle size is small, there is a risk that the solid electrolyte membrane may not have a smooth surface during press molding after mixing with the reinforcing factor 200.

Sulfide-based solid electrolyte particles having this size may be Li ₂ SP ₂ S ₅ , Li ₂ SP ₂ S ₅ -LiX (X=Cl, Br, I)-based compounds, or sulfides containing Li or Na ion conduction.

Second, in the case of the wet process, a reinforcing factor is mixed with a liquid sulfide-based solid electrolyte, wet mixed into a slurry, then coated with the slurry on the support, semi-dried or heat treated, and then molded with a press or roller to produce a solid electrolyte membrane. It's a method.

As seen in dry mixing, the sulfide-based solid electrolyte used in wet mixing also contains Li ₂ SP ₂ S ₅ , Li ₂ SP ₂ S ₅ -LiX (X=Cl, Br, I)-based compounds or Li or Na ion conduction. It may be a sulfide-based solid electrolyte particle.

At this time, the liquid sulfide-based solid electrolyte refers to a state in which sulfide-based solid electrolyte particles are mixed with a solvent. Here, the solvent is a solvent that can dissolve the sulfide-based solid electrolyte, such as an alcohol-based solvent, or a solvent that can dissolve the sulfide-based solid electrolyte particles. As a solvent that can be dispersed without dissolving, it is desirable to use a solvent that maintains ionic conductivity after manufacturing the solid electrolyte membrane or maintains it to a level that does not interfere with constructing an all-solid-state battery even if it is slightly lowered.

For example, one or more of hydrocarbon-based solvents, BTX-based solvents, ether-based solvents, and ester-based solvents can be selectively used.

Hydrocarbon-based solvents include pentane, hexane, 2-ethyl hexane, heptane, octane, cyclohexane, and methyl cyclohexane. Any one or more can be used selectively.

As the BTX-based solvent, one or more of hydrocarbon-based solvents, benzene, toluene, xylene, and ethylbenzene can be selectively used.

As the ether-based solvent, one or more of diethyl ether, tetrahyrofuran, and 1,4-dioxane can be selectively used.

As the ester-based solvent, one or more of ethyl propionate and propyl propionate can be selectively used.

It is desirable to select and use the above-mentioned solvent appropriately within or exceeding the solubility range of the sulfide-based solid electrolyte.

When coating slurry on a support such as polymer or metal during a wet process, slurry coating (bar coating, Dr Blade), dip coating (dip coating), spray coating (spray coating), spin coating and It may be performed by one or more of drop coating methods.

Likewise, when coating a slurry on an electrode in a wet process, slurry coating (bar coating, Dr Blade), dip coating (dip coating), spray coating (spray coating), spin coating (spin coating) and drop coating ( It can be done by one or more of the following methods (drop coating).

Additionally, during the wet process, the slurry can be compressed and molded with a press or roller to increase its density, and then heat-treated under temperature conditions of 30 to 550°C in a naturally dried state. Below 30°C, the temperature is weak for drying the slurry. In addition, it takes a long time to dry, which highlights the inefficiency of the process. If the temperature exceeds 550°C, there is a risk that the surface of the solid electrolyte membrane may break due to too high a temperature, and if heat treatment is performed at a temperature below that, Since excellent effects were not observed in comparison, it is preferable to heat treat at a temperature of 30 to 550°C.

The reinforcement factor (200) relative to the total volume of the solid electrolyte membrane obtained through this process may include 0.5 to 99% by volume. If the strengthening factor (200) relative to the total volume of the solid electrolyte membrane is less than 0.5% by volume, it is insignificant to provide mechanical strength to the sheet-shaped solid electrolyte membrane, and if it exceeds 99% by volume, the amount of sulfide-based solid electrolyte that can be added is There is a disadvantage in that it is difficult to maintain the shape of the solid electrolyte membrane because it becomes small and small spaces may be created between the reinforcing elements 200.

In addition, the thickness of the solid electrolyte membrane can range from 10nm to 300㎛. If it is less than 10nm, cracks occur frequently and there is a risk of breaking easily, and it is too thin to achieve free-standing. If it is exceeded, it becomes inflexible and there is a problem in that free-standing cannot be achieved, so it is preferable to have a thickness in the range of 10nm to 300㎛.

Additionally, the solid electrolyte membrane has no porosity limitations, but preferably has a porosity of less than 10%. Specifically, if the porosity exceeds 10%, not only are the physical properties poor, but the product quality is also poor, so it is desirable to have a porosity of 10%.

The solid electrolyte membrane completed in this way can have one-dimensional, two-dimensional, and three-dimensional shapes depending on the shape of the press and mold, and can be formed between the anode and the cathode.

Additionally, the slurry can be applied on the cathode through a wet process and dried/heat-treated to form a double layer, which can be used with the anode. The slurry can be applied on the anode through a wet process and dried/heat-treated to form a double layer to be used with the cathode. It may be possible.

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

<Example 1>

dry process

1. Powder preparation: Prepare powder of Li ₆ PS ₅ Cl (LPSCl), an argyrodite composition, using an energy ball mill using Li ₂ S, Li ₂ S ₅ , and LiCl.

2. Fiber preparation: Prepare polyimide fiber (10㎛ diameter, several mm long).

3. Dry mixing: Add less than 10% by volume of fiber to 0.15g of sulfide solid electrolyte (LPSCl) and mix.

4. Press: Weigh the mixed powder, put 0.01g, 0.02g, and 0.05g into a mold with a diameter of 13mm, spread it evenly, and apply pressure of about 4 tons.

5. Composite membrane: The manufactured composite membrane is composed of LPSCl solid electrolyte and polyimide fiber.

6. Lithium ion conductivity is also measured using the SUS/solid electrolyte/SUS structure.

Figure 2 is a photograph of a membrane according to a preferred embodiment of the present invention.

Figure 2-(a) shows a composite membrane manufactured to a thickness of 78㎛ by putting 0.01g of mixed powder of Li ₆ PS ₅ Cl (LPSCl) and polyimide fiber into a mold with a diameter of 13 mm, spreading it evenly, and then applying pressure of about 4 tons. This is a photo showing.

Figure 2-(b) shows a composite membrane manufactured to a thickness of 113㎛ by putting 0.02g of a mixed powder of Li ₆ PS ₅ Cl (LPSCl) and polyimide fiber into a mold with a diameter of 13 mm, spreading it evenly, and then applying pressure of about 4 tons. This is a photo showing.

In Figure 2-(c), polyimide fiber is not used, and only 0.1 g of Li ₆ PS ₅ Cl (LPSCl) is put into a mold with a diameter of 13 mm, spread evenly, and then pressure of about 4 tons is applied to create a composite membrane with a thickness of 535 ㎛. This is the picture shown.

According to the experimental results according to FIGS. 2-(a), 2-(b), and 2-(c), it can be confirmed that a membrane with free-standing properties cannot be manufactured if polyimide fiber is not used. .

Figure 3 is a table according to Figure 2. Referring to Figure 3, the LPSCI_0.01g sample shows the sample in Figure 2-(a), the LPSCI_0.02g sample shows the sample in Figure 2-(b), and the LPSCI_0.1g sample shows the sample in Figure 2-(c). will be. However, the LPSCI_0.05g sample in FIG. 3 is omitted in FIG. 2.

In particular, referring to Figure 3, the LPSCI_0.01g sample has an ionic conductivity of 3.88E-04S/cm, the LPSCI_0.02g sample has an ionic conductivity of 6.99E-04S/cm, and the LPSCI_0.05g sample has an ionic conductivity of 1.04 It can be confirmed that it has an ionic conductivity of E-03S/cm, and the LPSCI_0.1g sample has an ionic conductivity of 1.51E-03S/cm.

Figure 4 is a graph according to Figure 3. Referring to Figure 4, the resistance according to the thickness of the composite membrane can be confirmed. According to FIGS. 3 and 4, it can be confirmed that the resistance changes depending on Li mobility depending on the thickness of the membrane.

<Example 2>

wet process

1. Powder preparation: Prepare powder of Li ₆ PS ₅ Cl (LPSCl), an argyrodite composition, using a high energy ball mill using Li ₂ S, Li ₂ S ₅ , and LiCl.

2. Fiber preparation: Prepare polyimide fiber (10㎛ diameter, several mm long).

3. Wet mixing: A slurry prepared by adding less than 10% of fiber by volume to 0.15 g of sulfide solid electrolyte (LPSCl) and mixing the powder through a wet process using the solvent heptane with and without a PEPMNB binder. Bar coated on the surface of metal foil (e.g. Ni), dried at room temperature and heat treated at 100°C.

4. Press: After cutting the coated solid electrolyte and fiber composite sheet into appropriate sizes, apply pressure of about 4 tons.

5. Composite membrane: The manufactured composite membrane is composed of LPSCl solid electrolyte and polyimide fiber.

6. Lithium ion conductivity is also measured using metal/solid electrolyte/metal structure.

Figure 5 is a photograph of a membrane according to a preferred embodiment of the present invention. Figure 5-(a) is a photograph of the membrane when there is a binder, and Figure 5-(b) is a photograph of the membrane when there is no binder.

Figure 6 is a table according to Figure 5. Referring to Figure 6, the Binder(X) sample is shown in Figure 5-(b), and the Binder(O) sample is shown in Figure 5-(a). In particular, the binder (X) sample without binder in Figure 6 has an ionic conductivity of 7.28E-04S/cm, and the binder (O) sample has an ionic conductivity of 8.25E-04S/cm.

Figure 7 is a graph according to Figure 6. Referring to Figure 7, it can be seen that the resistance is shown depending on whether the binder exists or not.

The above description is merely an illustrative explanation of the technical idea of the present invention, and those skilled in the art will be able to make various modifications and variations without departing from the essential characteristics of the present invention.

Accordingly, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention, but are for explanation, and the scope of the technical idea of the present invention is not limited by these examples.

The scope of protection of the present invention should be interpreted in accordance with the scope of the patent claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of rights of the present invention.

100: Sulfide-based solid electrolyte
200: Reinforcement factor

Claims (8)

A first step of preparing a reinforcing factor in the form of a fiber or tube; and
Manufacturing a solid electrolyte membrane, including a second step of mixing the reinforcing factor with a sulfide-based solid electrolyte and then pressing and molding it into a certain shape,
The reinforcing factor in the first stage is,
The diameter is 1 nm to 200 μm,
It is at least one of polyimide (PI), polyamide (PAI), and polyvinylidene fluoride (PVDF),
In the second step,
If the sulfide-based solid electrolyte is in particle form, it is dry mixed,
If the sulfide-based solid electrolyte is in liquid form, it is wet mixed,
The solid electrolyte membrane is,
Characterized in that it is a free-standing membrane with improved mechanical strength as the reinforcing factor exists in a discontinuous state within the membrane.
Method for manufacturing a solid electrolyte membrane using reinforcing factors. delete delete According to paragraph 1,
In the second step,
A method of manufacturing a solid electrolyte membrane using a strengthening factor, characterized in that 1 to 99% by volume of the strengthening factor and 1 to 99% by volume of the sulfide-based solid electrolyte are mixed. In the solid electrolyte membrane,
A reinforcing element in the form of a fiber or tube; and
It is formed including a sulfide-based solid electrolyte,
A solid electrolyte membrane using a strengthening factor, characterized in that it is manufactured by the manufacturing method according to claim 1 or 4. According to clause 5,
The reinforcing factor is,
A solid electrolyte membrane using a reinforcing factor, characterized in that it is at least one of polyimide (PI), polyamide (PAI), and polyvinylidene fluoride (PVDF). According to clause 5,
The reinforcing factor is,
A solid electrolyte membrane using a strengthening factor, characterized in that it contains 0.5 to 99% by volume relative to the total volume of the solid electrolyte membrane. anode;
cathode; and
A solid electrolyte membrane formed between the anode and the cathode, which is formed by mixing a reinforcing element in the form of a fiber or tube and a sulfide-based solid electrolyte;
An all-solid-state battery comprising a solid electrolyte membrane using a strengthening factor, characterized in that it is manufactured by the manufacturing method according to claim 1 or 4.

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