KR20200050627A - Composite Electrode Including Gel-Type Polymer 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 gel-type polymer electrolyte, a manufacturing method thereof, and an all-solid-state lithium battery including the same. More specifically, according to the present invention, heterogeneous gel-type polymer electrolytes are 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 all-solid-state battery comprising a gel-type polymer electrolyte, a method for manufacturing the same, and an all-solid lithium battery comprising the same (Composite Electrode Including Gel-Type Polymer 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 of manufacturing the same, and an all-solid-state lithium battery comprising the same, and more specifically, a composite electrode in which a gel-type polymer electrolyte is infiltrated into an electrode, a method of manufacturing the same, and an all-solid body comprising the same It relates to a lithium battery.

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 a prior art in which the output and performance of the all-solid-state battery are lowered 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, by introducing a method for manufacturing a composite electrode with improved interface properties, an effort was made to manufacture an all-solid-state battery with reduced interface resistance and improved battery properties.

Accordingly, the present inventors infiltrate the gel-type heterogeneous polymer 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 electrode, and the pores in the electrode and By filling the interface between the components with a polymer electrolyte, a composite electrode for an all-solid-state battery with improved interfacial properties was manufactured, 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-state battery. The present invention was completed by confirming that it was done.

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

The object of the present invention is to infiltrate a gel-type heterogeneous polymer electrolyte to improve the bonding property of the interface between the bulk solid electrolyte and the electrode, and to polymerize the interface between pores and components in the electrode. It is to provide a composite electrode for an all-solid-state battery that is filled with an electrolyte and has improved interface properties.

Another object of the present invention comprises the steps of preparing a gel polymer electrolyte, applying a gel polymer electrolyte to the electrode top, infiltrating into the electrode, and then compressing the electrode for high-density of the composite electrode and improvement of the contact surface between particles. It is to provide a method for manufacturing a composite electrode for an all-solid-state battery with improved interface properties.

Another object of the present invention is to introduce a composite electrode having improved interfacial properties or a method for manufacturing the same, and when using it as an electrode of an all-solid-state battery, the interface resistance can be reduced to enable 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

Provided is 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 gel polymer electrolyte is uniformly infiltrated.

In addition, the present invention

i) preparing a composite electrode by mixing an electrode active material, a binder, a conductive material, and an inorganic solid electrolyte material;

ii) preparing a gel-type polymer electrolyte containing a lithium salt; And

iii) after applying a gel polymer electrolyte to the electrode top, uniformly infiltrating into the electrode; including, provides a method of manufacturing a composite electrode for an all-solid lithium battery.

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.

In addition, the present invention

i) preparing a composite electrode by mixing an electrode active material, a binder, a conductive material, and an inorganic solid electrolyte material;

ii) preparing a gel-type polymer electrolyte containing a lithium salt;

iii) applying a gel polymer electrolyte on the upper portion of the composite electrode, followed by uniformly infiltrating into the composite electrode;

iv) compressing the composite electrode; And

v) stacking a composite anode layer including a composite electrode, a solid electrolyte, and a lithium anode layer; provides a method for manufacturing an all-solid lithium battery.

In the present invention, the output and performance of the all-solid-state battery are due to the high resistance problem occurring at the composite electrode / solid-electrolyte interface in the all-solid-state battery and the solid electrolyte / constituent material (active material, conductive material, binder) interface in the composite electrode. In order to solve the problems of the prior art, which is deteriorated, an all-solid-state battery having reduced interface resistance and improved battery characteristics was manufactured by introducing a composite electrode manufacturing method with improved interface characteristics.

Specifically, the present invention infiltrates the composite electrode from the surface of the composite electrode to the inside to infiltrate a gel-type heterogeneous polymer electrolyte to improve the bonding property of the interface between the bulk solid electrolyte and the electrode. By filling the interface between pores and components with a polymer electrolyte, a composite electrode for an 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 1 and Example 1 through a scanning electron microscope (SEM) experiment.
5 is a rate characteristic evaluation results for the all-solid-state batteries prepared in Examples 1 and 2 and Comparative Examples 1 and 3.
6 is a charge and discharge evaluation and impedance analysis results for the all-solid-state batteries prepared in Example 3 and Comparative Example 2.

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 gel polymer electrolyte is uniformly infiltrated in the electrode.

The all-solid lithium battery composite electrode is a cathode layer formed by coating and drying the current collector, such as Al and Ni, after preparing a slurry by combining a positive electrode active material, a binder, a conductive material, and an inorganic solid electrolyte powder. And, it may be configured to include a gel-type polymer electrolyte impregnated into the electrode due to low viscosity.

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 ), but is not limited thereto, and can be used as long as it can be used in the art. Do.

The gel-type polymer electrolyte to be infiltrated into the composite electrode is preferably a polymer matrix based on a polyethylene gylcol (PEG) having a molecular weight of 5,000 to 20,000 with lithium salt added. At this time, in the case of PEG having a molecular weight of 5,000 or less, there is a problem that decomposition occurs easily during electrochemical evaluation after infiltration in the electrode, and in the case of a molecular weight of 20,000 or more, a sufficiently low viscous molten salt is mixed with a lithium salt at a temperature between 90 ° C and 120 ° C. It is difficult to be, there is a problem that it is difficult to sufficiently infiltrate into the electrode in a gel form.

The gel polymer electrolyte matrix is not limited to polyethylene glycol (PEG), and is a copolymer of polyvinylidene fluoride, vinylidene fluoride and hexafluoropropylene, polymethacrylate, polyacrylonitrile, and polydimethyl It may be composed of at least one selected from the group consisting of siloxanes, LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, LiC ₄ F for lithium salts 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, and LiI Can be.

In addition, the present invention

i) preparing a composite electrode by mixing an electrode active material, a binder, a conductive material, and an inorganic solid electrolyte material;

ii) preparing a gel-type polymer electrolyte containing a lithium salt; And

iii) after applying a gel polymer electrolyte to the electrode top, uniformly infiltrating into the electrode; including, provides a method of manufacturing a composite electrode for an all-solid lithium battery.

In the above method, the composite electrode for an all-solid lithium battery can be prepared by combining a positive electrode active material, a binder, a conductive material, and an inorganic solid electrolyte material to prepare a slurry, and then coating / drying for a current collector such as Al and Ni. have.

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 can 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, the gel-type polymer electrolyte to be infiltrated into the composite electrode is preferably a polymer matrix based on PEG (polyethylene gylcol) having a molecular weight of 5,000 to 20,000 with lithium salt added. At this time, in the case of PEG having a molecular weight of 5,000 or less, there is a problem that decomposition occurs easily during electrochemical evaluation after infiltration in the electrode, and in the case of a molecular weight of 20,000 or more, a sufficiently low viscous molten salt is mixed with a lithium salt at a temperature between 90 ° C and 120 ° C. It is difficult to be, there is a problem that it is difficult to sufficiently infiltrate into the electrode in a gel form.

In one embodiment of the present invention, the solid phase PEG and the solid lithium salt LiTFSI (LiC ₂ F ₆ NO ₄ S ₂ ) are stirred without a solvent, and a gel polymer electrolyte in the form of a molten salt having a low viscosity when heat-treated at 110 ^° C. is prepared. , After applying it to the electrode surface, After the gel polymer electrolyte is uniformly infiltrated into the electrode by pushing it with a blade, the polymer electrolyte layer remaining on the surface of the composite electrode is wiped off, and then the composite electrode is rolled through a roll press to increase the density of the composite electrode and improve the contact surface between particles in the electrode. It was prepared by pressing.

In the above method, the gel polymer electrolyte matrix is not limited to polyethylene glycol (PEG), and is a copolymer of polyvinylidene fluoride, vinylidene fluoride and hexafluoropropylene, polymethacrylate, and polyacrylic. Nitrile, and at least one selected from the group consisting of 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, and LiI It can be selected from the group consisting.

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 gel polymer electrolytes are infiltrated. have.

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 composite electrode by mixing an electrode active material, a binder, a conductive material, and an inorganic solid electrolyte material;

ii) preparing a gel-type polymer electrolyte containing a lithium salt;

iii) applying a gel polymer electrolyte on the upper portion of the composite electrode, followed by uniformly infiltrating into the composite electrode;

iv) compressing the composite electrode; And

v) stacking a composite anode layer including a composite electrode, a solid electrolyte, and a lithium anode layer; provides a method for 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, a polymer matrix based on PEG (polyethylene gylcol) with a molecular weight of 5,000 to 20,000 with lithium salt added is preferred as the gel polymer electrolyte to be infiltrated into the composite electrode.

Here, in the case of PEG of 5,000 or less, there is a problem that decomposition occurs easily during electrochemical evaluation after infiltration in the electrode, and in the case of 20,000 or more, it is difficult to mix with a lithium salt at a temperature between 90 ° C and 120 ° C to become a sufficiently low viscosity molten salt. , There is a problem that it is difficult to sufficiently infiltrate into the electrode in a gel form.

After applying the gel-like polymer electrolyte to the electrode surface, After pushing the blade with a gel-like polymer electrolyte uniformly infiltrating into the electrode, the electrode is compressed to produce a high-density composite anode with improved adhesion / adhesion in the composite electrode.

Thereafter, the composite anode / solid electrolyte / cathode may be stacked to prepare an all-solid lithium battery having improved interface and output characteristics between the solid electrolyte / composite electrodes.

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 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 70: 10: 10: 10 by weight ratio, dissolve in NMP (N-methyl pyrrolidinine) solution, coat the slurry uniformly on Al foil with doctor blade, and dry it sufficiently in a vacuum oven at 120 ℃ to 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.

The gel polymer electrolyte infiltrated into the composite anode was prepared as follows. PEG (molecular weight 10,000) and lithium salt LiTFSI are weighed to be [EO]: [Li] = 8: 1 (molar ratio), mixed and stirred for 1 hour or more at 110 ° C and solid polymer matrix and lithium salt form molten salt Melted with a melt to prepare a gel-type polymer electrolyte having a viscosity of 50 cps ~ 1,000 cps. Thereafter, an amount of 5 to 10 μl / cm ² was poured onto the surface of the composite anode, and then pushed with a Dr. Blade to uniformly infiltrate the gel polymer electrolyte into the electrode. After removing the polymer electrolyte layer remaining on the surface of the composite electrode, the composite electrode was compressed through a roll press to increase the density of the composite electrode and improve the contact surface between 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), dissolved, and stirred at 50 ° C. for 4 hours or more to perform polymerization. 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 a heterogeneous gel 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 composite positive electrode loading was changed to 7.5 mg / cm ² .

< Example  3>

All solids were prepared in the same manner as in <Example 1> except that the bulk solid electrolyte was changed to a pellet-type Li _1.4 Al _0.4 Ti _1.6 (PO ₄ ) ₃ (LATP) solid electrolyte instead of the PEO-LiClO ₄ polymer solid electrolyte. A lithium battery was produced.

< Comparative example  1>

An all-solid lithium battery was manufactured in the same manner as in <Example 1>, except that the gel 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 gel 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

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

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), PVdF (binder) in a weight ratio of 70: It was composed of 10:10:10, and a cross section of a composite electrode infiltrated with a PEG-based gel polymer electrolyte having a molecular weight of 10,000 was analyzed by SEM and EDS.

As shown in FIG. 3, in the case of the composite electrode in <Example 1>, it can be seen that the electrode plate is densely constructed from the SEM results of the cross-section, and the component of the LiTFSI lithium salt contained in the gel polymer electrolyte infiltrated from the EDS analysis results By confirming that S exists uniformly over the entire electrode cross-section, it was confirmed that the PEG-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 1> in which the gel 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 <Example 1>, the cross-sectional result of <Example 1> shows that the pores and cracks were filled with a gel polymer electrolyte to form a high-density uniform electrode, improving the interfacial properties within the electrode. I could confirm.

< Evaluation example  2> Battery rate  Characteristic experiment

A constant current application charging and discharging evaluation was performed on the all-solid lithium battery produced through <Example 1>, <Example 2>, and <Comparative Example 1>. 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 ° 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> and <Example 1>, where the electrode loading was 5 mg / cm ² , the 0.2 C capacity was similar to about 0.53 mAh cm ^-2 , but the high rate of 1 C capacity was 43% compared to 0.2 C And 93% (<Comparative Example 1> and <Example 1> in order) was found to have a large difference. In the case of <Example 1> in which the gel-type polymer electrolyte was impregnated, it showed excellent rate characteristics twice or more than that of <Comparative Example 1>. In the case of Comparative Example 3, which does not infiltrate the gel polymer electrolyte and instead contains 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 is lower than in Example 1 It was found that even if the polymer electrolyte is contained in the electrode, the actual performance is deteriorated without passing through the infiltration process.

The rate characteristic of <Example 2>, in which the electrode loading was increased to 7.5 mg / cm ² , showed 81% better performance than <Comparative Example 1> despite the increased electrode loading. These results confirmed that in the case of a composite electrode in which a gel polymer electrolyte is impregnated, the inter-electrode and electrode / solid electrolyte interface properties are improved, indicating excellent rate characteristics and performance.

< Evaluation example  3> Battery Charge / discharge  And impedance experiment

The constant current application charge / discharge evaluation and impedance analysis were performed on the all-solid lithium battery produced through <Example 3> and <Comparative Example 2>. The current density was applied to 0.2 C for both charging and discharging based on the weight of the positive electrode active material, the voltage range was 2.5 V to 4.2 V, the temperature was performed at 60 ° C, and the impedance evaluation was 5 within a frequency range of 10 ⁶ to 10 ^-1 Hz. It was measured by applying mV _rms voltage perturbation.

The experimental results are shown in FIG. 6. When charging and discharging evaluation experiments of <Comparative Example 2> and <Example 3> in which the pellet type LATP solid electrolyte was applied as a bulk solid electrolyte, as shown in FIG. 6, in the case of <Comparative Example 2>, charging and discharging was not performed at all. Compared to not, in the case of <Example 3>, it can be seen that normal charging and discharging occurs. As can be seen from the impedance results, it can be seen that, in the case of <Comparative Example 2>, the resistance components related to the contact resistance and the charge transfer reaction occurring at the interface are much larger than those of <Example 3>. From these results, in the case of the composite electrode in which the gel polymer electrolyte is impregnated, it was confirmed once again that the inter-electrode and electrode / solid electrolyte interface properties were improved to exhibit 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 gel polymer electrolyte is uniformly infiltrated in the electrode,
Composite electrode for all-solid lithium battery.
According to claim 1,
The gel polymer electrolyte is composed of polyethylene glycol (polyethylene gylcol, PEG), polyvinylidene fluoride, a 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 gel-type polymer electrolyte is a composite electrode for an all-solid lithium battery, characterized in that it is a polyethylene glycol-based polymer matrix having a molecular weight of 5,000 to 20,000 with lithium salt added.
i) preparing a composite electrode by mixing an electrode active material, a binder, a conductive material, and an inorganic solid electrolyte material;
ii) preparing a gel-type polymer electrolyte containing a lithium salt; And
iii) after applying a gel polymer electrolyte to the electrode top, uniformly infiltrating into the electrode; including,
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,
A composite positive electrode prepared by forming a composite electrode containing an electrode active material, a binder, a conductive material, and an inorganic solid electrolyte material, and then applying a gel polymer electrolyte and uniformly infiltrating the electrode;
Bulk solid electrolytes; And
Lithium negative electrode; All-solid lithium battery stacked in this order.
i) preparing a composite electrode by mixing an electrode active material, a binder, a conductive material, and an inorganic solid electrolyte material;
ii) preparing a gel-type polymer electrolyte containing a lithium salt;
iii) applying a gel polymer electrolyte on the upper portion of the composite electrode, followed by uniformly infiltrating into the composite 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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