KR20200050628A - Composite Electrode Including Polymer Solid Electrolyte for All-Solid-State Battery, Method Of Manufacturing The Same, And All-Solid-State Lithium Battery Comprising The Same - Google Patents

Abstract

The present invention relates to a composite electrode for an all-solid-state battery including a solid polymer electrolyte, a manufacturing method thereof, and an all-solid-state lithium battery including the same. More specifically, according to the present invention, a solid electrolyte based on heterogeneous polymers is impregnated into a surface of a composite electrode in which an electrode active material, a binder, a conductive material, and an inorganic solid electrolyte material are mixed, thereby increasing bonding properties between a bulk solid electrolyte and an electrode. Moreover, pores inside the electrode and an interface between components are filled with the polymer electrolyte, thereby increasing interface characteristics. Accordingly, an electrode/solid electrolyte interfacial resistance is decreased when the composite electrode is used as an electrode of an all-solid-state battery, thereby realizing high output and high performance of the all-solid-state battery.

Description

Composite electrode for an all-solid-state battery containing a polymer solid electrolyte, a method for manufacturing the same, and an all-solid lithium battery comprising the same (Composite Electrode Including Polymer Solid Electrolyte for All-Solid-State Battery, Method Of Manufacturing The Same, And All-Solid-State Lithium Battery Comprising The Same}

The present invention relates to a composite electrode for an all-solid-state battery, a method for manufacturing the same, and an all-solid-state battery comprising the same, more specifically, a composite electrode in which a polymer-based solid electrolyte is infiltrated into an electrode, a method for manufacturing the same, and It relates to an all-solid-state battery containing him.

Recently, research on lithium batteries has been actively conducted for efficient use of energy, and various efforts have been made to use them as energy sources in electric vehicles and power storage as well as small mobile electronic devices. However, in the case of an organic liquid electrolyte used in a commercially available lithium ion secondary battery, the risk of explosion / fire is very high, and in order to improve the safety of the battery, the need to replace it with a solid electrolyte has been continuously increasing.

The all-solid-state secondary battery using a solid electrolyte does not use a flammable organic electrolyte, and there is no fear of leakage or ignition of the electrolyte, and thus has excellent safety characteristics. The solid electrolyte can be largely divided into an inorganic-based sulfide-based and oxide-based, an organic-based polymer electrolyte, and an organic / inorganic solid-electrolyte hybrid hydride-based solid electrolyte. In the case of the sulfide-based solid electrolyte, lithium ion conduction characteristics are higher than those of the oxide-based electrolyte, but the hygroscopicity is strong and there is a high possibility that toxic hydrogen sulfide (H2S) is generated. As the oxide-based solid electrolyte material, LLZO (LiaLa3Zr2O12) having a garnet structure, LLTO (Li3aLa (2 / 3-a) □ (1 / 3-2a) TiO3) having a perovskite structure, and LATP (NASCON structure) Li1 + aAlaTi2-a (PO4) 3) and the like, and has excellent moisture, chemical, physical, and mechanical stability compared to sulfide-based solid electrolytes, but needs to improve low ion conductivity problems due to high grain boundary resistance. Polyethylene oxide, polyvinylidene fluoride, copolymer of vinylidene fluoride and hexafluoropropylene, polymethacrylate, polyacrylonitrile, polydimethylsiloxane, etc. are used as the polymer electrolyte. Recently, inorganic materials are used. Research has been conducted on organic and organic hybrid materials in which organic polymer materials are complex.

In the case of an all-solid-state battery, generally, the ionic conductivity of the solid electrolyte itself is low, and the positive electrode, the (solid) electrolyte, and the negative electrode constituting the battery are all solid, making it difficult to adhere and bond between the components, and the cells of each interface and battery. There is a disadvantage that it is difficult to achieve high performance and high output of the battery due to its very high resistance (JW Fergus, J. Power Sources 195, 4554-4569, 2010; and YC. Jung et al., J. Electrochem. Soc., 162 A704-A710, 2015). This may include a problem in that the conductivity is lowered due to an increase in resistance due to the limited contact area of ions and electrons that are conducted from the solid electrolyte to the electrode, and to solve this, as well as the electrode / solid electrolyte, current collector / electrode interface, , A high-density electrode with improved adhesion and adhesion between an active material, a solid electrolyte material, a binder, and a conductive material in an electrode must be manufactured, and an interface control technology capable of forming a uniform and improved interface is required (K Fu et al., Proc. Natl. Acad. Sci., 113, 7094-7099, 2016; and DH Kim et al., Nano Lett., 17,3013-3020, 2017).

The present inventors have reduced the output and performance of the all-solid-state battery due to the high resistance problem occurring at the interface of the electrode / solid-electrolyte in the all-solid-state battery and the solid electrolyte / constituent material (active material, conductive material, binder) in the electrode. In order to solve the problem of the technology, by introducing a method for manufacturing a composite electrode with improved interfacial properties, an effort was made to manufacture an all-solid-state battery with reduced interfacial resistance and improved battery characteristics.

Therefore, the present inventors infiltrate the surface of the composite electrode from the surface of the composite electrode to the inside by heating the heterogeneous polymer-based solid electrolyte, thereby improving the bonding property of the interface between the bulk solid electrolyte and the electrode, and the pores and composition in the electrode. The interface between the elements was filled with a polymer electrolyte to prepare a composite electrode for an all-solid-state battery with improved interfacial properties, and when it is used as an electrode for an all-solid-state battery, the interface resistance of the electrode / solid electrolyte is reduced to enable high power and high performance of the all-solid battery. The present invention was completed by confirming that.

J. W. Fergus, J. Power Sources 195, 4554-4569, 2010 Y-C. Jung et al., J. Electrochem. Soc., 162 A704-A710, 2015 K. Fu et al., Proc. Natl. Acad. Sci., 113, 7094-7099, 2016 D.H. Kim et al., Nano Lett., 17,3013-3020, 2017

An object of the present invention is to infiltrate (infiltration) a heterogeneous polymer-based solid electrolyte from the surface of the composite electrode to improve the bonding property of the interface between the bulk solid electrolyte and the composite electrode, and the pores and composition in the composite electrode It is to provide a composite electrode for a high-density all-solid-state battery having an improved interface property by filling the interface between elements with a polymer electrolyte.

Another object of the present invention is to prepare a polymer-based solid electrolyte, and then apply heat to the polymer solid electrolyte applied to the upper portion of the composite electrode in which an electrode active material, a binder, a conductive material, and an inorganic solid electrolyte material are mixed, to obtain a polymer electrolyte. It is to provide a method for manufacturing a composite electrode for a high-density all-solid-state battery comprising infiltrating into an electrode and then compressing the electrode for high-density composite electrode and improved contact surface between particles.

Another object of the present invention is to introduce a composite electrode for a high-density all-solid-state battery or a method for manufacturing the same, which can reduce the interface resistance when used as an electrode of the all-solid-state battery, thereby enabling high-power and high-performance of the all-solid-state battery. It is to provide an all-solid lithium battery comprising a composite electrode for a battery.

In order to achieve the above object, the present invention

It includes an electrode active material, a binder, a conductive material, and an inorganic solid electrolyte material,

The polymer-based solid electrolyte is uniformly infiltrated in the electrode,

Provided is a composite electrode for an all-solid lithium battery.

In addition, the present invention

i) preparing a polymer-based solid electrolyte containing a lithium salt;

ii) mixing an electrode active material, a binder, a conductive material, and an inorganic solid electrolyte material to produce a composite electrode; And

iii) applying a polymer solid electrolyte to the top of the electrode, and then applying heat to infiltrate the polymer electrolyte into the electrode.

Provided is a method of manufacturing a composite electrode for an all-solid lithium battery.

In addition, the present invention

Provided is an all-solid lithium battery including the composite electrode for an all-solid lithium battery according to the present invention.

In addition, the present invention

i) preparing a polymer-based solid electrolyte containing a lithium salt;

ii) mixing an electrode active material, a binder, a conductive material, and an inorganic solid electrolyte material to produce a composite electrode;

iii) applying a polymer solid electrolyte to the top of the electrode, and then applying heat to infiltrate the polymer electrolyte into the electrode;

iv) compressing the composite electrode; And

v) laminating a composite anode layer comprising a composite electrode, a solid electrolyte, and a lithium anode layer; comprising,

Provided is a method of manufacturing an all-solid lithium battery.

The present invention is due to the high resistance problem occurring at the interface of the composite electrode / solid electrolyte in the all-solid-state battery and the solid electrolyte / constituent material (active material, conductive material, binder) in the composite electrode, the output and performance of the all-solid-state battery In order to solve the problem of the deteriorating prior art, a composite electrode manufacturing method with improved interfacial characteristics was introduced to manufacture an all-solid-state battery with reduced interfacial resistance and improved battery characteristics.

Specifically, the present invention infiltrates a polymer-based solid electrolyte from the surface of the composite electrode to the inside to improve the bonding property of the interface between the bulk solid electrolyte and the composite electrode, and the pores in the composite electrode and By filling the interface between the components with a polymer electrolyte, a composite electrode for a high-density all-solid-state battery with improved interface properties was prepared, and when it was used as an electrode for an all-solid-state battery, it exhibited a high-power and high-performance effect of the all-solid-state battery.

1 is a view showing the configuration of an all-solid lithium battery proposed in the present invention.
2 is a view showing a step of manufacturing an all-solid lithium battery proposed in the present invention.
3 is a result showing the cross-sectional shape of the composite electrode prepared in Example 1 through a scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) experiment.
4 is a result showing the cross-sectional shape of the composite electrode prepared in Comparative Example 2 and Example 3 through a scanning electron microscope (SEM) experiment.
5 is a result of evaluating rate characteristics for the all-solid-state batteries prepared in Examples 1, 2, and 3 and Comparative Examples 1, 2, and 3.

Hereinafter, the present invention will be described in detail.

The present invention provides an electrode active material, a binder, a conductive material, and an inorganic solid electrolyte material, and provides a composite electrode for an all-solid lithium battery in which a polymer-based solid electrolyte is uniformly infiltrated in the electrode.

The all-solid lithium battery composite electrode is a positive electrode active material, a binder, a conductive material and an inorganic solid electrolyte powder formed by a slurry coating and drying process and a low viscosity due to a thermal process and a polymer solid electrolyte infiltrated into the electrode It may be configured to include.

The electrode active material may be used without limitation as long as it is a positive electrode active material commonly used in lithium batteries. For example, LiCoO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , LiNi _{1 - x} Mn _x O2 (0 <x <1), LiNi _{1 -x- y} Co _x Mn _y O ₂ (0 <x <0.5, 0 <y <0.5), LiFePO ₄ , TiS ₂ , FeS ₂ of lithium transition metal oxide or transition metal sulfide.

Examples of the binder include polyvinylidene fluoride (PVdF), styrene-butadiene rubber (SBR), and carboxy methyl cellulose (CMC), but are not limited thereto.

The conductive material is preferably selected from the group consisting of carbon black, acetylene black, ketjen black (KR), vapor grown carbon fiber (VGCF), and mixtures thereof. Does not.

The solid electrolyte powder added to the electrode contains lithium, and may include a general inorganic-based solid electrolyte having lithium ion conductivity characteristics. For example, LATP (Li _{1 + a} Al _a Ti _{2 -a} (PO ₄ ) ₃ ) having an oxide-based NASICON structure, LLZO (Li _x La ₃ Zr ₂ O ₁₂ ) having a garnet structure, perovskite structure It may be LLTO (Li ₃ La _{2 / (3-x)} TiO ₃ ), LIPON (Li _{3 -x} PO _4-x N _x ), etc., but is not limited thereto, and can be used as long as it can be used in the art. Do.

As the polymer solid electrolyte to be infiltrated into the composite electrode, it is preferable to select a PEO (polyethylene oxide) based solid electrolyte having a molecular weight of 50,000 to 1,000,000 with lithium salt added. At this time, in the case of PEO having a molecular weight of 50,000 or more, a lithium salt of LiClO ₄ is dissolved in an acetonitrile solvent and polymerized, and then poured uniformly onto a substrate made of PTFE and volatilized the solvent to freeze the polymer electrolyte layer. Can be produced. In the case of PEO having a molecular weight of 50,000 or less, it is difficult to prepare a free-standing polymer solid electrolyte, and when the molecular weight is 1,000,000 or more, it is difficult to secure a sufficiently low viscosity when infiltrating into the electrode by applying heat (100 ° C to 130 ° C). There is a problem that it is difficult to infiltrate into the uniform.

The matrix of the polymer solid electrolyte is not limited to polyethylene oxide (PEO), and is a copolymer of polyvinylidene fluoride, vinylidene fluoride and hexafluoropropylene, polymethacrylate, polyacrylonitrile, and polydimethylsiloxane LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, LiC ₄ F ₉ SO ₃ , LiAlO ₄ , LiAlCl ₄ , LiN (C _x F _{2x + 1} SO ₂ ) (C _y F _{2y + 1} SO ₂ ) (where x, y is a natural number), LiCl, LiI .

The solvent used in the preparation of the polymer solid electrolyte may be selected from the group consisting of tetrahydrofuran and acetonitrile.

In addition, the present invention

i) preparing a polymer-based solid electrolyte containing a lithium salt;

ii) mixing an electrode active material, a binder, a conductive material, and an inorganic solid electrolyte material to produce a composite electrode; And

iii) applying a polymer solid electrolyte to the top of the electrode, and then applying heat to infiltrate the polymer electrolyte into the electrode.

Provided is a method of manufacturing a composite electrode for an all-solid lithium battery.

In the above method, the composite electrode for an all-solid-state lithium battery may be prepared by complexing an active material, a binder, a conductive material, and an inorganic solid electrolyte material to coat the slurry for current collectors such as Al and Ni. A high-density composite with improved self-adhesiveness / adhesiveness in the composite electrode by placing a self-supporting polymer solid electrolyte on the electrode surface, applying heat from 100 ° C to 130 ° C to melt the polymer electrolyte, infiltrating the polymer electrolyte into the electrode, and compressing the electrode. Electrodes can be prepared.

In the above method, the steps i) and ii) are irrespective of order, and can be prepared by changing the order of each other.

In the above method, after step iii), the electrode may be further compressed to increase the density of the composite electrode and improve the contact surface between particles.

In the above method, the electrode active material may be used without limitation as long as it is a positive electrode active material commonly used in lithium batteries. For example, LiCoO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , LiNi _{1 - x} Mn _x O2 (0 <x <1), LiNi _{1 -x- y} Co _x Mn _y O ₂ (0 <x <0.5, 0 <y <0.5), LiFePO ₄ , TiS ₂ , FeS ₂ of lithium transition metal oxide or transition metal sulfide.

In the above method, polyvinylidene fluoride (PVdF), styrene-butadiene rubber (SBR), and carboxy methyl cellulose (CMC) are typical examples of the binder, but are not limited thereto.

In the above method, the conductive material is selected from the group consisting of carbon black, acetylene black, ketjen black (KR), vapor grown carbon fiber (VGCF) and mixtures thereof. Preferably, but not limited to.

In the above method, the solid electrolyte powder added to the electrode contains lithium, and may include a general inorganic-based solid electrolyte having conductivity characteristics of lithium ions. For example, LATP (Li _{1 + a} Al _a Ti _{2 -a} (PO ₄ ) ₃ ) having an oxide-based NASICON structure, LLZO (Li _x La ₃ Zr ₂ O ₁₂ ) having a garnet structure, perovskite structure It may be LLTO (Li ₃ La _{2 / (3-x)} TiO ₃ ), LIPON (Li _{3 - x} PO _{4 - x} N _x ), etc., but is not limited thereto, and can be used as long as it can be used in the art. Do.

In the above method, it is preferable to select a PEO (polyethylene oxide) based solid electrolyte having a molecular weight of 50,000 to 1,000,000 with lithium salt added as a polymer solid electrolyte to be infiltrated into the composite electrode. At this time, in the case of PEO having a molecular weight of 50,000 or more, the lithium salt of LiClO ₄ is dissolved in an acetonitrile solvent and polymerized, and then poured into a substrate made of PTFE material and volatilized to freeze the polymer electrolyte layer in a free-standing form. Can be produced. In the case of PEO having a molecular weight of 50,000 or less, it is difficult to prepare a free-standing polymer solid electrolyte, and when the molecular weight is 1,000,000 or more, it is difficult to secure a sufficiently low viscosity when infiltrating into the electrode by applying heat (100 ° C to 130 ° C). There is a problem that it is difficult to infiltrate into the uniform.

In one embodiment of the present invention, in order to apply and infiltrate the polymer-based solid electrolyte into the composite electrode, a self-supporting polymer electrolyte layer is applied on the surface of the composite electrode, and the composite electrode is heated to a temperature between 100 and 130 ° C, A method of applying a vacuum to infiltrate the melted polymer electrolyte was applied, and after wiping and removing the polymer electrolyte layer remaining on the composite electrode surface, the composite electrode was roll-pressed to increase the density of the composite electrode and improve the contact surface between particles in the electrode. It was prepared by pressing through.

In the above method, the matrix of the polymer solid electrolyte is not limited to polyethylene oxide (PEO), and is a copolymer of polyvinylidene fluoride, vinylidene fluoride and hexafluoropropylene, polymethacrylate, polyacrylonitrile , And polydimethylsiloxane, LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N , LiC ₄ F ₉ SO ₃ , LiAlO ₄ , LiAlCl ₄ , LiN (C _x F _{2x + 1} SO ₂ ) (C _y F _{2y + 1} SO ₂ ) (where x, y is a natural number), LiCl, LiI Can be selected from.

In addition, the present invention provides an all-solid lithium battery comprising the composite electrode for an all-solid lithium battery according to the present invention.

A composite positive electrode composed of a composite electrode for an all-solid lithium battery according to the present invention, a bulk solid electrolyte, and a lithium negative electrode may be sequentially stacked to provide an all-solid battery including a composite electrode in which heterogeneous polymer electrolytes are infiltrated.

The bulk solid electrolyte can be used as a solid electrolyte in the form of a pellet composed of an inorganic material, a polymer solid electrolyte in a membrane form having soft properties, and an organic-inorganic hybrid solid electrolyte in which a polymer electrolyte and an inorganic solid electrolyte are combined. Do. The inorganic solid electrolyte used at this time may contain lithium, and may include a general inorganic based solid electrolyte having lithium ion conductivity characteristics. For example, LATP (Li1 + aAlaTi2-a (PO4) 3) having an oxide-based NASICON structure, LLZO (LixLa3Zr2O12) having a garnet structure, LLTO (Li3La2 / (3-x) TiO3) having a perovskite structure) , LIPON (Li3-xPO4-xNx). It is not necessarily limited to these, and any that can be used in the art can be used.

The negative electrode can be used without limitation, as long as it is commonly used in lithium batteries in addition to lithium metal foil. For example, it may include one or more selected from the group consisting of metals, metal oxides and carbon-based materials alloyable with lithium. For example, the metal capable of alloying with lithium includes Si, Sn, Al, Ge, Pb, Bi, and the like, and the metal oxide is lithium titanium oxide, SnO2, SiOx (0 <x <2). Carbon-based materials may be crystalline carbon, amorphous carbon, or mixtures thereof.

The lithium battery is also suitable for applications requiring high safety and high volume, such as an electric vehicle, and can be used in a hybrid vehicle in combination with an existing internal combustion engine, fuel cell, supercapacitor, or the like. In addition, the lithium battery can be used for all other applications such as mobile small IT products such as mobile phones, portable computers.

In addition, the present invention

i) preparing a polymer-based solid electrolyte containing a lithium salt;

ii) mixing an electrode active material, a binder, a conductive material, and an inorganic solid electrolyte material to produce a composite electrode;

iii) applying a polymer solid electrolyte to the top of the electrode, and then applying heat to infiltrate the polymer electrolyte into the electrode;

iv) compressing the composite electrode; And

v) laminating a composite anode layer comprising a composite electrode, a solid electrolyte, and a lithium anode layer; comprising,

Provided is a method of manufacturing an all-solid lithium battery.

In the above method, the steps i) and ii) are irrespective of order, and can be prepared by changing the order of each other.

In the above method, in the case of a composite positive electrode, a positive electrode active material, a binder, a conductive material, and an inorganic solid electrolyte material may be composited to prepare a slurry coating for current collectors such as Al and Ni.

In the above method, it is preferable to select a PEO (polyethylene oxide) based solid electrolyte having a molecular weight of 50,000 to 1,000,000 with lithium salt added as a polymer solid electrolyte to be infiltrated into the composite electrode.

At this time, in the case of PEO having a molecular weight of 50,000 or more, a lithium salt of LiClO ₄ is dissolved in an acetonitrile solvent and polymerized, and then poured uniformly onto a substrate made of PTFE and volatilized the solvent to freeze the polymer electrolyte layer. Can be produced. In the case of PEO having a molecular weight of 50,000 or less, it is difficult to prepare a free-standing polymer solid electrolyte, and when the molecular weight is 1,000,000 or more, it is difficult to secure a sufficiently low viscosity when infiltrating into the electrode by applying heat (100 ° C to 130 ° C). There is a problem that it is difficult to infiltrate into the uniform.

Thereafter, in order to apply and infiltrate the polymer-based solid electrolyte into the composite electrode, a self-supporting polymer electrolyte layer is applied on the surface of the composite electrode, and the composite electrode is heated to a temperature between 100 and 130 ° C and melted by applying a vacuum. A method in which a true polymer electrolyte infiltrates can be applied.

Thereafter, after removing the polymer electrolyte layer remaining on the surface of the composite electrode, the composite electrode may be compressed through a roll press to increase the density of the composite electrode and improve the contact surface between particles in the electrode.

Thereafter, the composite positive electrode, the bulk solid electrolyte, and the lithium negative electrode may be sequentially stacked to complete the configuration of the all-solid-state battery including the composite electrode in which a heterogeneous polymer electrolyte is impregnated.

Hereinafter, the present invention will be described in detail by the following examples and evaluation examples.

However, the following examples and evaluation examples are merely illustrative of the present invention, and the contents of the present invention are not limited by the following examples and evaluation examples.

< Example  1>

The polymer solid electrolyte infiltrated into the composite anode was prepared as follows. PEO (molecular weight 100,000) and LiClO ₄ are weighed in ACN (actetonitile) solvent to [EO]: [Li] = 18: 1 (molar ratio), dissolved, and stirred at 50 ° C. for 4 hours or more to perform a polymerization process. Thereafter, the slurry was cooled at room temperature, poured onto a PTFE plate, coated with a 20 μm thickness through a doctor blade, dried, and peeled to prepare a self-supporting PEO-LiClO ₄ polymer electrolyte membrane.

The composite electrode is a positive electrode active material Li [Ni _0.6 Co _0.2 Mn _0.2 ] O ₂ (NCM), pre-treated Li _1.4 Al _0.4 Ti _1.6 (PO ₄ ) ₃ (LATP) powder, super-P (conductive material), PVdF (binding) Weigh) at 60: 20: 10: 10 by weight ratio, dissolve in NMP (N-methyl pyrrolidinine) solution, coat the slurry uniformly on Al foil with doctor blade, dry it sufficiently in a vacuum oven at 120 ℃, and NMP After volatilization of a solvent such as, an electrode plate was prepared. The loading of the prepared composite electrode was about 5 mg / cm ² . A lithium metal foil was used as the negative electrode.

In order to apply and infiltrate the polymer solid electrolyte into the composite electrode, a self-supporting PEO-LiClO ₄ polymer electrolyte membrane layer is applied on the surface of the composite anode, and the composite electrode is heated to a temperature of 120 ° C. to form a viscous liquid polymer. A method of dissolving the electrolyte layer, applying a vacuum for about 2 hours by placing it in a vacuum chamber to infiltrate the liquid polymer electrolyte into the composite electrode, and then wiping and removing the remaining polymer electrolyte layer on the surface of the composite electrode, and then increasing the density of the composite electrode And it was compressed through the roll press of the composite electrode to improve the contact surface between the particles in the electrode.

As a bulk solid electrolyte, a free-standing polymer solid electrolyte was prepared as follows. PEO (molecular weight 600,000) and LiClO ₄ were weighed in ACN (actetonitile) solvent to be [EO]: [Li] = 18: 1 (molar ratio) and dissolved, followed by stirring at 50 ^° C for 4 hours or more to perform a polymerization process. Thereafter, the slurry was cooled at room temperature, poured onto a PTFE plate, coated with a 40 μm thickness through a doctor blade, dried, and peeled to prepare a self-supporting PEO-LiClO ₄ polymer electrolyte membrane.

Thereafter, a composite positive electrode in which heterogeneous polymer electrolyte was impregnated, a bulk polymer electrolyte, and a lithium negative electrode foil were stacked as shown in FIG. 1 to prepare an all-solid lithium battery.

< Example  2>

An all-solid lithium battery was manufactured in the same manner as in <Example 1> except that the molecular weight of the PEO polymer impregnated in the composite anode was changed to 600,000.

< Example  3>

Positive electrode active material of composite electrode Li [Ni _0.6 Co _0.2 Mn _0.2 ] O ₂ (NCM), pre-treated Li _1.4 Al _0.4 Ti _1.6 (PO ₄ ) ₃ (LATP) powder, super-P (conductive material), PVdF (binding) All) was prepared in the same manner as in <Example 1>, except that the weight ratio was changed to 70: 10: 10: 10 in the weight ratio.

< Comparative example  1>

An all-solid lithium battery was manufactured in the same manner as in <Example 1>, except that the polymer electrolyte was not applied and infiltrated.

< Comparative example  2>

An all-solid lithium battery was manufactured in the same manner as in <Example 3>, except that the polymer electrolyte was not applied and infiltrated.

<Comparative Example 3>

Anode active material Li [Ni _0.6 Co _0.2 Mn _0.2 ] O ₂ (NCM), pre-treated Li _1.4 Al _0.4 Ti _1.6 (PO ₄ ) ₃ (LATP) powder, super-P (conductive material), PEO-LiClO ₄ (binding <Example> except that the composite electrode (loading: 5 mg / cm ² ) composed of 70: 10: 10: 10 by weight ratio of the agent and the polymer electrolyte) was applied, and an additional gel polymer electrolyte was not applied and infiltrated. An all-solid lithium battery was manufactured in the same manner as in 1>.

< Evaluation example  1> Scanning electron microscope ( SEM ) And energy dispersive spectroscopy (EDS) experiments

Scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) experiments were performed to understand the cross-sectional characteristics of the composite anodes prepared in <Example 1>, <Comparative Example 2>, and <Example 3>.

The experimental results are shown in FIGS. 3 and 4. In <Example 1>, the composite electrode has a positive electrode active material Li [Ni _0.6 Co _0.2 Mn _0.2 ] O ₂ (NCM), a pre-treated LATP powder, super-P (conductive material), and PVdF (binder) in a weight ratio of 60: 20:10:10, and cross-sections of a composite electrode infiltrated with a PEO-based solid electrolyte having a molecular weight of 100,000 were subjected to SEM and EDS analysis.

As shown in FIG. 3, in the case of the composite electrode in <Example 1>, it can be seen from the SEM results of the cross-section that the electrode plate was densely constructed, and from the EDS analysis results, the LiClO ₄ lithium salt contained in the infiltrated PEO polymer electrolyte By confirming that the component Cl is uniformly present over the entire electrode cross-section, it was confirmed that the PEO-based polymer electrolyte was successfully infiltrated into the electrode and distributed through the process.

In addition, as shown in FIG. 4, in the case of the composite electrode of <Comparative Example 2> in which the PEO-based polymer electrolyte is not infiltrated, the active material and the solid electrolyte powder, the conductive material, the binder, and the like are not in close contact, and pores and cracks are interfacial. On the other hand, it was confirmed that it occurred in the <Example 3> cross-sectional results, it can be seen that the pores and cracks are filled with a polymer electrolyte to form a relatively high-density uniform electrode, improving the interfacial properties in the electrode I could confirm that.

< Evaluation example  2> Battery rate  Characteristic experiment

A constant current application charging and discharging evaluation was performed for the all-solid lithium batteries produced through <Example 1>, <Example 2>, <Example 3>, <Comparative Example 1>, and <Comparative Example 2>, respectively. Based on the weight of the positive electrode active material, the current density was equal to 0.2 C, and the discharge was applied differently to 0.2 C and 1 C. The voltage range was 2.5 V to 4.2 V, the temperature was performed at 60 ^o C, and the rate characteristics were evaluated by comparing the discharge capacity of 1 C compared to the 0.2 C discharge capacity.

The experimental results are shown in FIG. 5. In the case of <Comparative Example 1>, <Example 1> and <Example 2> having an electrode composition ratio of 6: 2: 1: 1, the 0.2 C capacity was similar to about 0.53 mAh cm ^-2 , The high rate of 1 C dose was 42%, 72%, and 57% (<Comparative Example 1>, <Example 1>, <Example 2>) compared to 0.2C. Both <Example 1> and <Example 2> in which the polymer electrolyte was impregnated showed excellent rate characteristics compared to <Comparative Example 1>, which were not. <Example 1> in which a polymer electrolyte having a molecular weight of 100,000 is infiltrated is superior to <Example 2> in a molecular weight of 600,000 because the viscosity of the polymer electrolyte is lowered due to the low molecular weight and is more uniformly infiltrated into the electrode. Is judged. In the case of <Comparative Example 2> and <Example 3> having an electrode composition ratio of 7: 1: 1: 1, similar results were also obtained. In particular, in the case of Comparative Example 3, which does not infiltrate the polymer electrolyte and instead includes the polymer electrolyte component in the composite electrode, the capacity of the low rate 0.2 C and the high rate 1.0 is 0.476 mAh cm ^-2 and 0.271 mAh cm ^-2 , respectively, which are lower than in Example 3 By showing, even if the polymer electrolyte is contained in the electrode, it can be seen that the actual performance is deteriorated without passing through the infiltration process. From this, in the case of the composite electrode in which the polymer electrolyte is infiltrated, the inter-electrode and electrode / solid electrolyte interface properties are improved. It was confirmed that it exhibited excellent rate characteristics and performance.

Claims (8)

It includes an electrode active material, a binder, a conductive material, and an inorganic solid electrolyte material,
The polymer-based solid electrolyte is uniformly infiltrated in the electrode,
Composite electrode for all-solid lithium battery.
According to claim 1,
The polymer-based solid electrolyte is composed of polyethylene oxide (polyethylene oxide, PEO), polyvinylidene fluoride, copolymer of vinylidene fluoride and hexafluoropropylene, polymethacrylate, polyacrylonitrile, and polydimethylsiloxane A composite electrode for an all-solid lithium battery, characterized in that any one or two or more selected from the group.
According to claim 1,
The polymer-based solid electrolyte is a composite electrode for an all-solid lithium battery, characterized in that it is a polyethylene oxide-based solid electrolyte with a molecular weight of 50,000 to 1,000,000 to which lithium salt is added.
i) preparing a polymer-based solid electrolyte containing a lithium salt;
ii) mixing an electrode active material, a binder, a conductive material, and an inorganic solid electrolyte material to produce a composite electrode; And
iii) applying a polymer solid electrolyte to the top of the electrode, and then applying heat to infiltrate the polymer electrolyte into the electrode.
Method for manufacturing a composite electrode for an all-solid lithium battery.
The method of claim 4,
After the step iii), the method of manufacturing a composite electrode for an all-solid-state lithium battery further comprising the step of compressing the electrode to increase the density of the composite electrode and improve the contact surface between particles.
An all-solid lithium battery comprising the composite electrode for an all-solid lithium battery of claim 1.
The method of claim 6,
After forming a composite electrode containing an electrode active material, a binder, a conductive material, and an inorganic solid electrolyte material, a composite anode is directly contacted with a composite electrode by applying and infiltrating a polymer solid electrolyte in the composite electrode;
Bulk solid electrolytes; And
Lithium negative electrode; All-solid lithium battery stacked in this order.
i) preparing a polymer-based solid electrolyte containing a lithium salt;
ii) mixing an electrode active material, a binder, a conductive material, and an inorganic solid electrolyte material to produce a composite electrode;
iii) applying a polymer solid electrolyte to the top of the electrode, and then applying heat to infiltrate the polymer electrolyte into the electrode;
iv) compressing the composite electrode; And
v) laminating a composite anode layer comprising a composite electrode, a solid electrolyte, and a lithium anode layer; comprising,
Method for manufacturing an all-solid lithium battery.

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