KR20180031949A - Manufacturing method of duplex solid electrolyte membrane, duplex solid electrolyte membrane thereof and manufacturing method all solid state cell thereof - Google Patents

Abstract

The present invention relates to a method for producing a duplex solid electrolyte membrane capable of improving state of physical contact between phosphorus oxide or metal oxide used as a solid electrolyte, by forming a porous solid electrolyte layer on one or both sides of a high density solid electrolyte layer. The present invention further relates to a duplex solid electrolyte membrane produced thereby, and a method for producing an all solid battery using the same. By forming the porous solid electrolyte layer, it is possible to reduce a difference in shrinkage rate of the high density solid electrolyte when sintered, and to create a gradient in porosity in accordance with the depth, thereby preventing delamination, and achieving excellent state of contact among solid electrolytes.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for producing a duplex solid electrolyte membrane, a duplex solid electrolyte membrane produced thereby, and a manufacturing method of a solid electrolyte cell using the duplex solid electrolyte membrane.

The present invention relates to a process for producing a duplex solid electrolyte membrane which improves the physical contact state between a metal oxide or phosphorous oxide used as a solid electrolyte by forming a porous solid electrolyte layer on both sides or one side of a high density solid electrolyte layer and a duplex solid electrolyte And a method for producing all-solid-state batteries using the same.

Although liquid electrolytes are used as electrolytes in commercialized lithium secondary batteries, the disadvantages of lithium secondary batteries have been increasingly exploited as they are used in electric vehicles and large-sized storage devices.

Liquid electrolytes present a risk of fire or explosion when leakage occurs in the air. The amount of lithium secondary batteries used in electric vehicles and large-scale storage devices is considerably high, which may lead to fires and hazards far greater than the explosion of portable batteries .

In addition, since the voltage at which decomposition occurs in the liquid electrolyte is 4.5V, the lifetime of the battery is greatly reduced at a voltage higher than that, so that the driving voltage can not be limited to 4.5V or less. Accordingly, a secondary battery using a liquid electrolyte has a loss of energy and a relatively low energy capacity. When a secondary battery having a small energy capacity is used in an electric vehicle, a large number of batteries must be used to compensate for a small energy capacity, which may increase the volume and weight and adversely affect the fuel efficiency of the electric vehicle.

Further, since the liquid electrolyte reacts with air, it can not be manufactured in the air as a secondary battery, and a process for preventing leakage due to liquid form is required, which increases manufacturing cost due to complicated process and manufacturing environment.

Disadvantages of such liquid electrolytes can be solved by using solid electrolytes.

The solid electrolyte has a safe and usable voltage range of 5V or higher because it does not have a risk of fire or explosion and can have a high energy capacity that can be used for driving a high voltage battery. In addition, the oxide solid electrolyte is easy to synthesize in the air and does not require a sealing process, so that the process is easy and the manufacturing cost is low.

However, in the case of an oxide solid electrolyte, physical contact between particles is not smooth and shows high resistance. In addition, the oxide solid electrolyte must be heat-treated at a high temperature, but has a problem that most active materials and electron conductors are side-reacted with each other at high temperatures (Korean Patent Publication No. 2010-0108955). Therefore, in order to commercialize the pre-oxide solid electrolyte battery, a solution for solving the problems of the oxide solid electrolyte is needed.

Patent Document 1: Korean Patent Publication No. 2010-0108955 (Oct. 10, 2010)

The present inventors have found that when a pre-solid battery is manufactured by using a duplex solid electrolyte membrane having a porous solid electrolyte layer formed on both sides or one side of a high-density solid electrolyte layer, physical contact between oxide particles of the solid electrolyte is improved, And the performance of the battery can be improved. Thus, the present invention has been completed.

Accordingly, the present invention provides a method of manufacturing a duplex solid electrolyte membrane in which physical contact between a metal oxide or a phosphorous solid electrolyte is improved.

The present invention also provides a method for manufacturing a pre-solid battery which improves the battery performance by improving the contact state of the metal oxide or the phosphorous solid electrolyte.

In order to solve the above problems, the present invention provides a process for producing a porous solid electrolyte, comprising the steps of: (a) placing a precursor mixture in a mold to form a first porous solid electrolyte layer; (b) depositing a solid electrolyte powder on the first porous solid electrolyte layer to form a high-density solid electrolyte layer; And (c) forming a pellet by pressurizing the first porous solid electrolyte layer-high density solid electrolyte layer and heat-treating the first porous solid electrolyte layer-high density solid electrolyte layer.

The present invention also provides a method for preparing a porous solid electrolyte, comprising: (a) forming a first porous solid electrolyte layer by putting a precursor mixture in a mold; (b) depositing a solid electrolyte powder on the first porous solid electrolyte layer to form a high-density solid electrolyte layer; (c) depositing a precursor mixture on the high-density solid electrolyte layer to form a second porous solid electrolyte layer; And (d) forming a pellet by pressing the stacked first porous solid electrolyte layer-high density solid electrolyte layer-second porous solid electrolyte layer, followed by heat treatment, thereby providing a method of manufacturing a duplex solid electrolyte membrane .

The present invention also provides a method of manufacturing a duplex solid electrolyte membrane, comprising the steps of: (a) preparing a solid electrolyte membrane produced by the method of manufacturing the duplex solid electrolyte membrane; (b) mixing the active material, the electron conductor, the binder and the solvent to prepare a slurry; (c) forming an electrode by impregnating and drying the slurry on one surface of the duplex solid electrolyte membrane; And (d) depositing a slurry on the other surface of the duplex solid electrolyte membrane and drying or vapor-depositing a metal thin film on the other surface of the duplex solid electrolyte membrane.

The present invention is characterized in that a pellet in which a porous solid electrolyte layer and a high density solid electrolyte layer are laminated by using a pre-solid mixture and a solid electrolyte powder is subjected to heat treatment to form a duplex solid electrolyte membrane, whereby a physical contact between the metal oxide State, and when used in the production of all solid-state cells, the resistance of all solid-state cells is greatly reduced to improve the performance of the battery.

In addition, the present invention can achieve excellent contact state by mixing volatile additives in the entire solid mixture to increase the size and porosity of the pores, or to prevent a lag phenomenon by giving a gradient of porosity.

1 is a flowchart illustrating a method of manufacturing a duplex solid electrolyte membrane according to an embodiment of the present invention.
2 is a flowchart illustrating a method of manufacturing a duplex solid electrolyte membrane according to another embodiment of the present invention.
3 is a flowchart showing a method for producing a solid electrolyte powder used in the present invention.
4 is a cross-sectional view of a duplex solid electrolyte membrane according to an embodiment of the present invention.
5 is an electron microscope image of a cross section of a duplex solid electrolyte membrane according to an embodiment of the present invention.
6 is a flowchart illustrating a method of manufacturing a pre-solid battery according to an embodiment of the present invention.
7 is a cross-sectional view of a pre-solid battery according to an embodiment of the present invention.
FIG. 8 is a flowchart illustrating a process of forming an electrode in a method for manufacturing a pre-solid battery according to an embodiment of the present invention.

Hereinafter, the present invention will be described more specifically based on preferred embodiments of the present invention. However, the following embodiments are merely examples for helping understanding of the present invention, and thus the scope of the present invention is not limited or limited.

The 'Duplex Solid Electrolyte Membrane' of the present invention serves as a separator between the positive electrode and the negative electrode. The 'Duplex Solid Electrolyte Membrane' of the present invention comprises a dense solid electrolyte layer (hereinafter referred to as a 'dense solid electrolyte layer' (Hereinafter, referred to as a "first porous electrolyte layer or a second porous electrolyte layer") that allows the ions to move in and out during charging and discharging by widening the contact area of the porous electrolyte layer. At this time, the porous solid electrolyte layer exists in the positive electrode and the negative electrode, and the porous electrolyte layer exists only in the one electrode.

In other words, the duplex solid electrolyte membrane of the present invention is composed of the first porous solid electrolyte layer-the high-density solid electrolyte layer, or the first porous solid electrolyte layer-the high-density solid electrolyte layer.

The solid electrolyte to be used in the preparation of the duplex solid electrolyte membrane of the present invention includes all the metal oxides and phosphorous solid electrolytes which can be synthesized by the solid phase method and which do not greatly improve contact only by applying pressure.

The pores of the duplex solid electrolyte of the present invention can be formed by a substance which is simply phase-wise volatilized through heat treatment of the precursor. In order to reduce the amount of pores, the precursor and the synthesized solid electrolyte can be mixed and controlled, and additional high temperature decomposition and volatile additives can be mixed and controlled to stretch.

The slurry containing the active material and the electron conductor together with a solvent and a binder is impregnated into a duplex solid electrolyte, dried, and then coated with an electron conductor on the upper and lower surfaces of the slurry.

The positive electrode and the negative electrode to be applied to the pre-solid battery including the duplex solid electrolyte of the present invention include all the active materials capable of charging and discharging ions.

Specifically, the present invention provides a process for producing a porous solid electrolyte comprising: (a) forming a first porous solid electrolyte layer by putting a precursor mixture into a mold; (b) depositing a solid electrolyte powder on the first porous solid electrolyte layer to form a high-density solid electrolyte layer; And (c) forming a pellet by pressurizing the first porous solid electrolyte layer-high density solid electrolyte layer and heat-treating the stacked first porous solid electrolyte layer-high density solid electrolyte layer. Respectively.

The present invention also provides a method for preparing a porous solid electrolyte, comprising: (a) forming a first porous solid electrolyte layer by putting a precursor mixture in a mold; (b) depositing a solid electrolyte powder on the first porous solid electrolyte layer to form a high-density solid electrolyte layer; (c) depositing a precursor mixture on the high-density solid electrolyte layer to form a second porous solid electrolyte layer; And (d) forming a pellet by pressing the first porous solid electrolyte layer-high density solid electrolyte layer-second porous solid electrolyte layer to form a pellet, and heat-treating the pellet. , And FIG. 2 is a flowchart showing a manufacturing method thereof.

Hereinafter, a method for producing a duplex solid electrolyte membrane according to the present invention will be described in detail.

In the step of forming the first porous electrolyte (step (a)), 30 mg to 100 mg of the precursor mixture is placed in the mold and flattened by applying a pressure to uniformly spread.

Here, in order to make the pellets having the predetermined size, a mold having the size of the set pellets, that is, the inner diameter corresponding to the diameter of the pellets can be prepared. Preferably, the diameter of the pellets is 0.5 cm to 3 cm. When the diameter of the pellet is less than 0.5 cm, the area is small and the efficiency of the battery can be lowered. When the pellet diameter is more than 3 cm, the difficulty of making uniform pellets can be increased.

At this time, the precursor mixture includes at least one selected from the group consisting of a lithium precursor, an aluminum precursor, a germanium precursor, and a phosphate precursor.

Next, in the step of forming the high-density solid electrolyte layer (step (b)), 100 to 800 mg of the solid electrolyte powder is applied, and the mixture is equilibrated by applying a pressure to uniformly spread.

Here, as shown in FIG. 3, the method for producing a solid electrolyte powder includes the steps of (i) pulverizing a precursor mixture to form a precursor mixture powder; (Ii) drying the precursor mixture powder; (Iii) heat treating the dried precursor mixture powder to obtain a solid electrolyte; And (iv) pulverizing the solid electrolyte to obtain a solid electrolyte powder.

Specifically, the step ((i)) of the precursor mixture powder may be performed by ball milling to form a mixture powder by pulverizing the precursor mixture. Wherein the precursor mixture comprises at least one selected from the group consisting of a lithium precursor, an aluminum precursor, a germanium precursor, and a phosphate precursor.

The precursor mixture is introduced into an acetone solvent in detail and then subjected to ball milling for 4 to 12 hours to pulverize the agglomerated powder in the precursor to prepare a uniformly mixed mixture. At this time, in ball milling, zirconia balls having a diameter of 3 to 10 mm can be used.

Next, the drying step ((ii)) of the precursor mixture may be performed by using a hot plate to dry the mixed powder at a temperature of 80 to 110 in the atmosphere.

The dried precursor mixture powder obtained in the step (ii) is heat-treated to obtain a solid electrolyte (step (iii)). The dried precursor mixture powder is further pulverized into a mortar, charged into an alumina crucible, 900 to synthesize a solid electrolyte. At this time, the heating rate is 2.5 to 3.5 / min, and the reaction can be performed at 850 to 900 for 1 to 2 hours so that the solid reaction takes place. After heating, it can be naturally cooled to room temperature.

Finally, in the step (iv) of obtaining the solid electrolyte powder from the solid electrolyte obtained in the step (iii), the solid electrolyte synthesized by using a planetary ball mill is pulverized to form a solid electrolyte powder . For example, a zinc oxide (ZrO ₂ ) vessel is mixed with a zinc oxide (ZrO ₂ ) ball having a diameter of about 1 mm at a ratio of 1: 1 by volume and then milled at 300 to 500 rpm for 4 to 12 hours. Lt; / RTI > for one hour.

When the solid electrolyte powder thus obtained is used, it is advantageous to use an atomized solid electrolyte of high purity. The synthesized solid electrolyte is stored in a place where the carbon dioxide and moisture are blocked.

In the step (c) of forming the second porous electrolyte layer, 30 mg to 100 mg of the entire solid mixture is applied to the high-density solid electrolytic layer, and flattened by applying a pressure uniformly spread. At this time, the second porous electrolyte layer may not be formed (see FIG. 1).

When the total solid mixture is used in an amount less than 30 mg, it is too thin to spread uniformly. When the total solid mixture is used in an amount exceeding 100 mg, it may become thicker and the efficiency may decrease. However, the amount of the pre-solid mixture and the solid electrolyte powder used in the present invention may be variously used depending on the amount or thickness of the active material to be used in the subsequent process.

Finally, the first porous solid electrolyte layer-high density solid electrolyte layer-second porous solid electrolyte layer laminated through steps (a), (b), and (c) is pressed to form pellets and heat- Thereby forming an electrolyte membrane (step (e)). If the second porous solid electrolyte layer is not formed, the stacked first porous solid electrolyte layer-high density solid electrolyte layer is pressed to form pellets and heat-treated to form a duplex solid electrolyte membrane.

The pressurization is preferably carried out within a pressure range of 2 to 6 metric tons. When the pressure is less than 2 metric tons, there is a problem in the molded body, which is difficult to maintain the molded body. When the pressure exceeds 6 metric tons, powder deformation occurs and is not preferable for sintering.

The pellets may also be heat treated to form a duplex solid electrolyte according to the present invention wherein the pellets are placed in a furnace and heated at a temperature of 900-1050 < 0 > C

For 2 to 10 hours and then furnace cooling to proceed with phase synthesis of the precursor, sintering and sintering of the solid electrolyte to form a duplex solid electrolyte. When the heating temperature is lower than 900 ° C, phase synthesis is insufficient and impurities are present. When the heating temperature is higher than 1050 ° C, deterioration of properties occurs due to lithium deficiency phenomenon. The heating time is 10 hours for a low temperature of 900 ° C and 2 hours for a high temperature of 1050 ° C so that sufficient energy is transferred to the material.

On the other hand, in order to maintain a good contact state between the porous solid electrolyte layer and the high-density solid electrolyte layer, the porosity of the first or second porous solid electrolyte may be varied to provide a stepwise gradient or a gradient of porosity.

To this end, when forming the first or second porous solid electrolyte layer, a volatile additive that is decomposed and volatized at a high temperature may be mixed to increase the pore size and amount of the porous solid electrolyte layer.

Particularly, in order to make pores connected three dimensionally and to facilitate penetration of the active material and the electron conductor, a carbon nanofiber (CNF), an electron polyvinylpyrrolidone (PVP) prepared by electro spinning, Polyvinylpyrrolidone), and polyvinyl alcohol (PVA) may be mixed into the precursor mixture.

The volatile additive is preferably used in an amount of 80 wt% or less based on the total weight of the precursor mixture. More preferably, the volatile additive is used in an amount of 40 to 80% by weight based on the total weight of the precursor mixture. More preferably 40 to 60% by weight. If the amount of the volatile additive is more than 80% by weight, the proportion of the precursor (or solid electrolyte) may be too low to achieve sintering, and ion conduction in the porous solid electrolyte layer may not be smooth.

By using the volatile additive, the porous solid electrolyte layer having a large number of pores can be located outside the pellet, thereby reducing the shrinkage of the portion contacting the high-density solid electrolyte layer, thereby preventing the pitting phenomenon.

At this time, in the present invention, by forming the porous solid electrolyte layer having different porosity from 2 to 3 layers with different amounts of the volatile additive, the fringing phenomenon can be improved.

In other words, when forming the porous electrolyte layer, it is possible to provide a stepwise difference in porosity as a method for more stable contact with the solid electrolyte layer during sintering. For example, the porous solid electrolyte layer in which the ratio of the volatile additive is varied is stacked in layers to reduce the difference in the shrinkage ratio between sintering of the respective layers, or a gradient of the porosity depending on the depth, Can be achieved. Preferably, the porosity is decreased as the layer is closer to the high-density solid electrolyte layer. The higher the density, the better the ion transport properties, because the role of the high density layer is a complete ion conductor.

In addition, in order to improve the cell performance, the porous solid electrolyte layer may include a mixed ion conductor in which the entire solid mixture is capable of conduction of both ions and electrons. The porous solid electrolyte layer comprising the mixed ion conductor can reduce the resistance and increase the performance. At this time, the mixed ion conductor may be at least one selected from the group consisting of Li-LiLaTiO3, Li-Si compound, and Li-Sn compound.

4 is a cross-sectional view of a duplex solid electrolyte according to the present invention. The first porous solid electrolyte layer 11, the high-density solid electrolyte layer 12, the negative electrode active material, and the electron conductor are inserted into the positive electrode active material and the electron conductor And a second porous solid electrolyte layer (13).

FIG. 5 is a scanning electron microscope image of a cross-section of a duplex solid electrolyte membrane according to the present invention, wherein pores of a porous solid electrolyte layer and a boundary portion between a porous solid electrolyte layer and a high density solid electrolyte layer can be identified.

The obtained duplex solid electrolyte membrane according to the present invention has a porosity of 40 to 70% and a pore size of 20 to 3000 nm, and is used for manufacturing all solid-state batteries.

Accordingly, the present invention provides a process for preparing a duplex solid electrolyte membrane, comprising the steps of: (a) preparing a duplex solid electrolyte membrane produced by the method of claim 1 or 2; (b) mixing the active material, the electron conductor, the binder and the solvent to prepare a slurry; (c) forming the anode by impregnating the slurry on one surface of the duplex solid electrolyte membrane and drying the slurry; And (d) drying the slurry on the other surface of the duplex solid electrolyte membrane or depositing a metal thin film to form a negative electrode. The method may further include the step (e) of forming an electron conductor layer by depositing an electron conductor on one surface of the duplex solid electrolyte membrane in which the metal thin film or slurry has penetrated after step (d). 6 is a flowchart illustrating a method for manufacturing a pre-solid battery according to the present invention.

Specifically, as described above, a pre-duplex solid electrolyte membrane according to the present invention is prepared (step (a)).

Next, a slurry is prepared by mixing the active material, the electron conductor, the binder and the solvent (step (b)).

The active material may be at least one selected from the group consisting of lithium manganese oxide (LiMn ₂ O ₄ ), lithium iron phosphate (LiFePO ₄ ), and lithium titanate (Li ₄ T ₅ O ₁₂ ) Can be used.

The electron conductor may be at least one selected from the group consisting of carbon and graphene. The binder may be polyvinylidene fluoride. N-methyl-2-pyrrolidone (hereinafter referred to as NMP) may be used as the solvent.

For example, about 160 mg of lithium manganese oxide (LiMn ₂ O ₄ ), about 30 mg of carbon and about 10 mg of PVDF binder were mixed in a mortar, and about 10 drops of NMP solvent was added as a syringe, followed by stirring for about 1 hour To prepare a slurry.

Next, the slurry prepared in step (b) may be impregnated on one surface of the duplex solid electrolyte membrane prepared in step (a) and dried to form the anode (step (c)). In this case, the drying may be performed at 60 to 80 ° C to form the anode of the duplex solid electrolyte.

In addition, the slurry may be penetrated and dried on the other surface of the duplex solid electrolyte membrane, or a metal thin film may be deposited to form a cathode (step (d)). The metal thin film at this time may be lithium metal (Li metal). 8 is a flowchart showing a step of forming an electrode in a method of manufacturing a full solid cell according to the present invention.

Finally, as shown in FIG. 7, an electron conductor may be deposited or coated on the surface of the duplex solid electrolyte into which the slurry has permeated to form an all solid-state battery having an electron conductor layer formed thereon (step (e)). The electron conductor layer can be formed on the surface of the duplex solid electrolyte so that the electron can be easily obtained. At this time, the electron conductor layer may include at least one selected from the group consisting of gold (Au) and platinum (Pt).

7 is a cross-sectional view of a pre-solid battery according to the present invention, which includes a first electron conductor layer 21 for collecting electrons in the anode, a first porous solid electrolyte layer 22 containing a cathode active material and an electron conductor, A high density solid electrolyte layer 23, a second porous solid electrolyte layer 24 containing a negative electrode active material and an electron conductor, and a second electron conductor layer 25 for collecting electrons of the negative electrode.

Accordingly, the present invention provides a pre-duplex solid electrolyte membrane having improved physical contact between oxides or phosphates used as a solid electrolyte by forming a first or a second porous electrolyte layer on a high-density solid electrolyte layer, The battery performance can be improved by greatly reducing the resistance of the entire solid-state battery.

Hereinafter, the present invention will be described in more detail with reference to examples. However, these examples are for illustrating the present invention, and the scope of the present invention is not limited thereto.

Example  One: First porosity The solid electrolyte layer  - High density The solid electrolyte layer - second porosity The solid electrolyte layer  When formed Porosity 30% )

Positive electrode: LiMn ₂ O ₄ , negative electrode: LiMn ₂ O ₄ , solid electrolyte: Li _{1 . 5} Al _{0 . 5 Ge 1 .5 (PO 4)} 3

Li ₂ CO ₃ + 1/3 Al ₂ O ₃ + 2 GeO ₂ + 4 (NH ₄ ) ₂ HPO ₄

As a precursor for the solid-phase reaction, 0.3991 g of Li ₂ CO ₃ powder (purity: 99% or more), Al ₂ O ₃ powder (having a purity of 98% or more ), 1.0870 g of GeO ₂ (purity of 99.99% or more) and 2.7380 g of (NH ₄ ) ₂ HPO ₄ (purity of 98% or more) were prepared and the undifferentiated mixing work was carried out using a mortar bowl in a solid powder state .

Next, to prepare a solid electrolyte powder, 10 g of the prepared precursor mixture was added to an acetone solvent, followed by ball milling for about 12 hours to obtain a homogeneously mixed mixture while pulverizing the agglomerated powder in the precursor. Zirconia balls having diameters of 3 mm, 5 mm and 10 mm are mixed in the ball mill. After mixing the powders through ball milling, the mixture is dried in air at a temperature of 110 ° C using a hot plate. Next, the dried powder is charged into alumina crucible in a mortar and heated to 900 ° C in the air. At this time, the heating rate is 3.125 ° C / min, and the reaction is carried out at 900 ° C for 2 hours to cause a solid-phase reaction. After heating, cool to room temperature. The thus synthesized solid electrolyte (LAGP) was pulverized using a planetary ball mill. In this case, a 1 mm diameter zinc oxide (ZrO ₂ ) ball and a synthesized solid electrolyte powder were mixed at a ratio of 1: 1 by volume in a zinc oxide (ZrO ₂ ) tube, and then pulverized at 500 rpm for one hour. Then, acetone was added thereto at 500 rpm for one hour Crush it. Thereafter, the ball of zinc oxide (ZrO ₂ ) is filtered out and dried at 110 ° C in the atmosphere using a hot plate to prepare a solid electrolyte powder. In addition, a mold having an inner diameter of 13 mm is prepared.

Using the thus prepared precursor mixture, solid electrolyte powder and mold, all solid-state batteries are manufactured in the following manner.

Specifically, 50 mg of the precursor mixture was placed in a mold, flattened by applying a uniformly spreading pressure, 400 mg of a solid electrolyte powder was spread on the flattened plate, and then 50 mg of the precursor mixture was flattened thereon. Thereby forming an electrolyte / precursor layer. Then, the pressure corresponding to 4 metric tons is applied for 1 minute, and the pellet is taken out from the mold.

Next, the pellets are placed in a furnace, heated in air at 800 ° C for 2 hours, and then subjected to furnace cooling to proceed with phase synthesis of the precursor, sintering, and sintering of the solid electrolyte, thereby completing the duplex solid electrolyte film.

Next, a lithium manganese oxide (LiMn ₂ O ₄ ) capable of both charging and discharging at the anode and the cathode is used as the electrode to be a symmetric battery. Carbon is used as an electronic conductor. 160 mg of lithium manganese oxide (LiMn ₂ O ₄ ), 30 mg of carbon, and 10 mg of PVDF binder were mixed in a mortar, and 10 drops of solvent NMP as a syringe was added, followed by stirring for 1 hour to prepare a slurry.

The prepared slurry was permeated into one surface of the duplex solid electrolyte membrane and then dried at 80 deg. After the weight of the penetrated electrode is measured, the slurry is equally penetrated into the other surface of the duplex solid electrolyte membrane, dried, and the weight is measured.

Next, platinum (Pt) is deposited on both sides of the duplex solid electrolyte to a thickness of 200 nm by using a sputterer in order to minimize the resistance of the dried surface to contact with the electron collector (SUS rod).

Example  2: first porosity The solid electrolyte layer  - High density The solid electrolyte layer - second porosity The solid electrolyte layer  When formed Porosity 30% )

Positive electrode: LiFePO ₄ , negative electrode: Li ₄ Ti ₅ O ₁₂ , solid electrolyte: Li _{1 . 5} Al _{0 . 5 Ge 1 .5 (PO 4)} 3

Li ₂ CO ₃ + 1 / 3Al ₂ O ₃ + 2GeO ₂ + 4 (NH ₄ ) ₂ HPO ₄

As a precursor for the solid-phase reaction, 0.3991 g of Li ₂ CO ₃ powder (purity of 99% or more), Al ₂ O ₃ powder (purity of 98% or more) were mixed to obtain a total synthesis amount of 3 g, 1.0870 g of GeO ₂ (purity of 99.99% or more) and 2.7380 g of (NH ₄ ) ₂ HPO ₄ (purity of 98% or more) are prepared and mixed to prepare a precursor mixture.

Next, to prepare a solid electrolyte powder, 10 g of the prepared precursor mixture is added to an acetone solvent, followed by ball milling for about 12 hours to obtain a homogeneously mixed mixture while pulverizing the agglomerated powder in the precursor. Zirconia balls having diameters of 3 mm, 5 mm and 10 mm are mixed in the ball mill. After mixing the powders through ball milling, the mixture is dried in air at a temperature of 110 ° C using a hot plate. Next, the dried powder is charged into alumina crucible in a mortar and heated to 900 ° C in the air. At this time, the heating rate is 3.125 ° C / min, and the reaction is carried out at 900 ° C for 2 hours to cause a solid-phase reaction. After heating, cool to room temperature. The synthesized solid electrolyte (LAGP) was pulverized using a planetary ball mill. In this case, a 1 mm diameter zinc oxide (ZrO ₂ ) ball and a synthesized solid electrolyte powder were mixed at a ratio of 1: 1 by volume in a zinc oxide (ZrO ₂ ) tube, and then pulverized at 500 rpm for one hour. Then, acetone was added thereto at 500 rpm for one hour Crush it. Thereafter, the ball of zinc oxide (ZrO ₂ ) is filtered out and dried at 110 ° C in the atmosphere using a hot plate to prepare a solid electrolyte powder. In addition, a mold having an inner diameter of 13 mm is prepared.

Using the thus prepared precursor mixture, solid electrolyte powder and mold, all solid-state batteries are manufactured in the following manner.

Specifically, 50 mg of the precursor mixture was placed in a mold, flattened by applying a uniformly spreading pressure, 400 mg of a solid electrolyte powder was spread on the flattened plate, and then 50 mg of a precursor mixture was flattened thereon. Thereby forming an electrolyte / precursor layer. Then, the pressure corresponding to 4 metric tons is applied for 1 minute, and the pellet is taken out from the mold.

Next, the pellets are placed in a furnace, heated in air at 800 ° C for 2 hours, and then subjected to furnace cooling to proceed with phase synthesis of the precursor, sintering, and sintering of the solid electrolyte, thereby completing the duplex solid electrolyte film.

Next, LiFePO ₄ is used for the anode, Li ₄ Ti ₅ O ₁₂ is used for the cathode, and carbon is used for the electron conductor as the electrode. Here, 160 mg of LiFePO ₄ , 30 mg of carbon, and 10 mg of PVDF binder were mixed in a mortar bowl, 10 drops of solvent NMP as a sphere were added to the anode, and the mixture was stirred for 1 hour to prepare a slurry. 160 mg of Li4Ti5O12, 30 mg of carbon and 10 mg of PVDF binder were mixed in a mortar, and 10 drops of solvent NMP as a sphere were added to the negative electrode, followed by stirring for 1 hour to prepare a slurry.

The prepared positive electrode slurry was permeated into one side of the duplex solid electrolyte membrane and then dried at 80 캜. After measuring the weight of the infiltrated electrode, the negative electrode slurry is similarly permeated into the other surface of the duplex solid electrolyte membrane, dried, and the weight is measured. Calculate charge / discharge currents for each active material in the anode and cathode centered on the lower capacity side.

Next, platinum (Pt) is deposited to a thickness of 200 nm on both sides of the duplex solid electrolyte using a sputter.

Example  3: first porosity The solid electrolyte layer  - High density The solid electrolyte layer  When formed Porosity 30% )

Positive electrode: LiFePO ₄ , negative electrode: Li metal, solid electrolyte: Li _{1 . 5} Al _{0 . 5 Ge 1 .5 (PO 4)} 3

Li ₂ CO ₃ + 1 / 3Al ₂ O ₃ + 2GeO ₂ + 4 (NH ₄ ) ₂ HPO ₄

As a precursor for the solid-phase reaction, 0.3991 g of Li ₂ CO ₃ powder (purity of 99% or more), Al ₂ O ₃ powder (purity of 98% or more) were mixed to obtain a total synthesis amount of 3 g, 1.0870 g of GeO ₂ (purity of 99.99% or more) and 2.7380 g of (NH ₄ ) ₂ HPO ₄ (purity of 98% or more) are prepared and mixed to prepare a precursor mixture.

Next, to prepare a solid electrolyte powder, 10 g of the prepared precursor mixture is added to an acetone solvent, followed by ball milling for about 12 hours to obtain a homogeneously mixed mixture while pulverizing the agglomerated powder in the precursor. Zirconia balls having diameters of 3 mm, 5 mm and 10 mm are mixed in the ball mill. After mixing the powders through ball milling, the mixture is dried in air at a temperature of 110 ° C using a hot plate. Next, the dried powder is charged into alumina crucible in a mortar and heated to 900 ° C in the air. At this time, the heating rate is 3.125 ° C / min, and the reaction is carried out at 900 ° C for 2 hours to cause a solid-phase reaction. After heating, cool to room temperature. The synthesized solid electrolyte (LAGP) was pulverized using a planetary ball mill. In this case, a 1 mm diameter zinc oxide (ZrO ₂ ) ball and a synthesized solid electrolyte powder were mixed at a ratio of 1: 1 by volume in a zinc oxide (ZrO ₂ ) tube, and then pulverized at 500 rpm for one hour. Then, acetone was added thereto at 500 rpm for one hour Crush it. Thereafter, the ball of zinc oxide (ZrO ₂ ) is filtered out and dried at 110 ° C in the atmosphere using a hot plate to prepare a solid electrolyte powder. In addition, a mold having an inner diameter of 13 mm is prepared.

Using the thus prepared precursor mixture, solid electrolyte powder and mold, all solid-state batteries are manufactured in the following manner.

More specifically, 400 mg of the solid electrolyte powder is placed in a mold, flattened by applying a uniformly spreading pressure, and 50 mg of a precursor mixture is laid on it to form a solid electrolyte / precursor layer. Then, the pressure corresponding to 4 metric tons is applied for 1 minute, and the pellet is taken out from the mold.

Next, the pellets are placed in a furnace, heated in air at 800 ° C for 2 hours, and then subjected to furnace cooling to proceed with phase synthesis of the precursor, sintering, and sintering of the solid electrolyte, thereby completing the duplex solid electrolyte film.

Next, LiFePO ₄ is used for the anode and carbon is used for the electron conductor as the electrode. Here, 160 mg of LiFePO ₄ , 30 mg of carbon, and 10 mg of PVDF binder were mixed in a mortar bowl, 10 drops of solvent NMP as a sphere were added to the anode, and the mixture was stirred for 1 hour to prepare a slurry.

The prepared positive electrode slurry was permeated into one side of the duplex solid electrolyte membrane and then dried at 80 캜. A Li metal foil is attached to the other surface of the duplex solid electrolyte membrane and used as a cathode.

Next, platinum (Pt) is deposited to a thickness of 200 nm on both sides of the duplex solid electrolyte using a sputter.

Example  4: Porosity using volatile additives The electrolyte layer  (Porosity of 40%)

Positive electrode: LiFePO ₄ , negative electrode: Li ₄ Ti ₅ O ₁₂ , solid electrolyte: Li _{1 . 5} Al _{0 . 5 Ge 1 .5 (PO 4)} 3

Li ₂ CO ₃ + 1 / 3Al ₂ O ₃ + 2GeO ₂ + 4 (NH ₄ ) ₂ HPO ₄

As a precursor for the solid-phase reaction, 0.3991 g of Li ₂ CO ₃ powder (purity of 99% or more), Al ₂ O ₃ powder (purity of 98% or more) were mixed to obtain a total synthesis amount of 3 g, , 1.0870 g of GeO ₂ (purity of 99.99% or more) and 2.7380 g of (NH ₄ ) ₂ HPO ₄ (purity of 98% or more) were prepared and mixed to prepare a precursor mixture. In order to increase the pore size and porosity of the porous solid electrolyte layer, carbon nanofibers (CNF) were added to the precursor mixture at a weight ratio of 6: 4 and mixed uniformly to form a precursor mixture .

Next, to prepare a solid electrolyte powder, 10 g of the prepared precursor mixture is added to an acetone solvent, followed by ball milling for about 12 hours to obtain a homogeneously mixed mixture while pulverizing the agglomerated powder in the precursor. Zirconia balls having diameters of 3 mm, 5 mm and 10 mm are mixed and used for the ball milling. After mixing the powders through ball milling, the mixture is dried in the air at a temperature of 110 DEG C by using a hot plate. The powder is poured into a mortar and then charged into an alumina crucible and heated to 900 ° C in the air. At this time, the heating rate is 3.125 ° C / min, and the reaction is carried out at 900 ° C for 2 hours to cause a solid-phase reaction. After heating, cool to room temperature.

The synthesized solid electrolyte (LAGP) was pulverized using a planetary ball mill. In this case, a 1 mm diameter zinc oxide (ZrO ₂ ) ball and a synthesized solid electrolyte powder were mixed at a ratio of 1: 1 by volume in a zinc oxide (ZrO ₂ ) tube, and then pulverized at 500 rpm for one hour. Then, acetone was added thereto at 500 rpm for one hour Crush it. Thereafter, the ball of zinc oxide (ZrO ₂ ) is filtered out and dried at 110 ° C in the atmosphere using a hot plate to prepare a solid electrolyte powder. In addition, a mold having an inner diameter of 13 mm is prepared.

Using the thus prepared precursor mixture, solid electrolyte powder and mold, all solid-state batteries are manufactured in the following manner.

Specifically, 50 mg of the precursor mixture was placed in a mold, flattened by applying a uniformly spreading pressure, 400 mg of a solid electrolyte powder was spread on the flattened plate, and then 50 mg of the precursor mixture was flattened thereon. Thereby forming an electrolyte / precursor layer. Then, the pressure corresponding to 4 metric tons is applied for 1 minute, and the pellet is taken out from the mold.

Next, the pellets are placed in a furnace, heated in air at 800 ° C for 2 hours, and then subjected to furnace cooling to proceed with phase synthesis of the precursor, sintering, and sintering of the solid electrolyte, thereby completing the duplex solid electrolyte film.

Next, LiFePO ₄ is used for the anode, Li ₄ Ti ₅ O ₁₂ is used for the cathode, and carbon is used for the electron conductor as the electrode. 160 mg of LiFePO ₄ , 30 mg of carbon and 10 mg of PVDF binder were mixed in a mortar, and 10 drops of solvent NMP as a sphere were added to the anode, followed by stirring for 1 hour to prepare a slurry. 160 mg of Li4Ti5O12, 30 mg of carbon and 10 mg of PVDF binder were mixed in a mortar, and 10 drops of solvent NMP as a sphere were added to the cathode, followed by stirring for 1 hour to prepare a slurry.

The prepared positive electrode slurry was permeated into one side of the duplex solid electrolyte membrane and then dried at 80 캜. After measuring the weight of the infiltrated electrode, the negative electrode slurry is similarly permeated into the other surface of the duplex solid electrolyte membrane, dried, and the weight is measured. Calculate charge / discharge currents for each active material in the anode and cathode centered on the lower capacity side.

Next, platinum (Pt) is deposited to 200 nm on both sides of the duplex solid electrolyte using a sputter.

Comparative Example  1: Conventional All solid-state cells

All the solid state batteries were fabricated using the conventional pressure molding process. The pre-compression type solid-state battery manufacturing method is a method in which an active material is sequentially formed on both sides of a solid electrolyte sintered in the form of pellets and then heat-treated. At this time, LiFePO4 was used as the cathode active material and Li4Ti5O12 was used as the anode active material.

Experimental Example  1: Measurement of battery performance

The charging / discharging evaluations of the all-solid-state batteries prepared in Examples 1 to 4 and Comparative Examples 1 and 2 were conducted under constant current conditions for charging / discharging evaluation of a typical battery, and the results are shown in Table 1 below .

division Porosity 1) Pore size 2) Cell shape Battery performance measurement result Example 1 30% 0.1 to 1 um Symmetric cell
LMO / LMO Unmeasured Example 2 30% 0.1 to 1 um Full cell
LFP / LTO 25 mAh / g Example 3 30% 0.1 to 1 um Half cell
LFP / Li 30 mAh / g Example 4 40% 0.1 to 1 um Full cell
LFP / LTO 60 mAh / g Comparative Example 1 0 0 - Battery can not be driven 1) Mean porosity of the porous solid electrolyte layer.
2) Porous solid electrolyte layer mean average pore size.

As shown in Table 1, in the case of Example 1, charge / discharge evaluation was not performed as a model test for confirming penetration of the active material into the pore structure. Example 2 is a full cell, and Example 3 is a half cell for confirming cell activity.

In the case of Comparative Example 1, it was impossible to confirm the battery reaction at room temperature as a conventional all solid-state battery which does not include the duplex solid electrolyte membrane according to the present invention. This is because the activation energy is increased due to the high interface resistance and there is no lithium ion transfer reaction at room temperature.

On the other hand, in the case of Example 2 according to the present invention, a capacity of 25 mAh / g was confirmed at room temperature with a cell configuration in which the interfacial contact area between the active material and the electrolyte was greatly increased to a porosity of 30%. In case of Example 4, it is understood that the cell capacity is increased to 60 mAh / g when the porosity is increased up to 40%

Accordingly, the present invention provides a pre-duplex solid electrolyte membrane that improves the physical contact state between the metal oxide or the phosphorous solid electrolyte by forming the pre-solid mixture and the solid electrolyte powder into a pellet in which the porous solid electrolyte layer and the high-density solid electrolyte layer are laminated And the resistance of the entire solid-state battery can be greatly reduced by applying it to the entire solid-state cell.

Further, it can be seen that the volatile additive is mixed with the whole solid mixture to increase the pore size and the porosity, or to give a gradient of the porosity to prevent the lag phenomenon and achieve the excellent contact state.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. In addition, it is a matter of course that various modifications and variations are possible without departing from the scope of the technical idea of the present invention by anyone having ordinary skill in the art.

11, 22: a first porous solid electrolyte layer
12, 23: High density solid electrolyte layer
13, 24: second porous solid electrolyte layer
21, 22: first and second electron conductor layers

Claims (17)

(a) placing a precursor mixture in a mold to form a first porous solid electrolyte layer;
(b) depositing a solid electrolyte powder on the first porous solid electrolyte layer to form a high-density solid electrolyte layer; And
(c) forming a pellet by pressurizing the stacked first porous solid electrolyte layer-high density solid electrolyte layer and subjecting the pellet to heat treatment;
And a second solid electrolyte layer formed on the first solid electrolyte layer.
(a) placing a precursor mixture in a mold to form a first porous solid electrolyte layer;
(b) depositing a solid electrolyte powder on the first porous solid electrolyte layer to form a high-density solid electrolyte layer;
(c) depositing a precursor mixture on the high-density solid electrolyte layer to form a second porous solid electrolyte layer; And
(d) pressing the first porous solid electrolyte layer-high density solid electrolyte layer-second porous solid electrolyte layer to form pellets and heat-treating the stacked first porous solid electrolyte layer-high density solid electrolyte layer-
And a second solid electrolyte layer formed on the first solid electrolyte layer.
The method of claim 1 or 2, wherein the precursor mixture comprises at least one selected from the group consisting of a lithium precursor, an aluminum precursor, a germanium precursor, and a phosphate precursor.
The process for preparing a duplex solid electrolyte membrane according to claim 1 or 2, wherein a volatile additive is added to the precursor mixture in an amount of 40 to 80 wt% so that a porosity of the porous electrolyte layer is 20 to 70%.
The porous electrolyte membrane according to claim 1 or 2, wherein porosity gradient is formed by layering the porous electrolyte layer by varying the ratio of the volatile additive to the precursor mixture, and the porosity is decreased as the porous electrolyte layer is closer to the high density solid electrolyte layer Wherein the solid electrolytic film has a thickness of at least 20 占 퐉.
The duplex solid body according to claim 4, wherein the volatile additive is one kind of a member selected from the group consisting of carbon nanofiber, polyvinylpyrrolidone, and polyvinyl alcohol. A method for producing an electrolyte membrane.
The duplex solid electrolyte membrane according to claim 1 or 2, wherein the precursor mixture comprises at least one mixed ion conductor selected from the group consisting of Li-LiLaTiO3, Li-Si compound, and li-Sn compound. Gt;
The method according to claim 1 or 2, wherein the solid electrolyte powder
(I) pulverizing the precursor mixture to form a precursor mixture powder;
(Ii) drying the precursor mixture powder;
(Iii) heat treating the dried precursor mixture powder to obtain a solid electrolyte; And
(Iv) obtaining a solid electrolyte powder obtained by pulverizing said solid electrolyte;
And a second solid electrolyte layer formed on the first solid electrolyte layer.
3. The method according to claim 1 or 2,
Wherein the precursor mixture is used in an amount of 30 mg to 100 mg.
3. The method according to claim 1 or 2,
Wherein the solid electrolyte powder is used in an amount of 100 mg to 800 mg.
3. The method according to claim 1 or 2,
Wherein the pressure is applied by applying a pressure of 2 to 6 metric tons to form a pellet.
3. The method according to claim 1 or 2,
Wherein the heat treatment is performed at 900 to 1050 ° C for 2 to 10 hours.
The duplex solid electrolyte membrane according to claim 1 or 2, wherein the porosity is in the range of 20 to 70%.
(a) preparing a duplex solid electrolyte membrane produced by the method of claim 1 or 2;
(b) mixing the active material, the electron conductor, the binder and the solvent to prepare a slurry;
(c) forming the anode by impregnating the slurry on one surface of the duplex solid electrolyte membrane and drying the slurry; And
(d) depositing a slurry on the other surface of the duplex solid electrolyte membrane and drying or depositing a metal thin film to form a negative electrode;
≪ RTI ID = 0.0 > 1, < / RTI >
15. The method of claim 14,
Wherein the metal thin film comprises lithium metal (Li metal).
15. The method of claim 14,
The method may further include the step (e) of forming an electron conductor layer by depositing an electron conductor on one surface of the duplex electrolyte membrane having the metal thin film or the slurry after the step (d) Gt; to < / RTI >
17. The method of claim 16,
Wherein the electron conductor layer comprises at least one selected from the group consisting of gold (Au) and platinum (Pt).

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