KR20230084865A - All solid state electrode layer - Google Patents

Abstract

An all-solid electrode layer according to an embodiment of the present invention may be formed by stacking heterogeneous electrode structures. An all-solid electrode layer according to an embodiment of the present invention may include an ion diffusion-based electrode layer and a composite electrode layer stacked on the ion diffusion-based electrode layer and including a solid electrolyte and an active material.

Description

All solid electrode layer {ALL SOLID STATE ELECTRODE LAYER}

The present invention relates to an all-solid-state electrode layer, and more particularly to an all-solid-state electrode layer having heterogeneous electrode structures having different characteristics.

In general, since lithium ion secondary batteries have a higher energy density than other batteries, research and demand for medium and large-sized secondary batteries such as energy storage systems (ESS, energy storage systems) and secondary batteries for electric vehicles in addition to portable electronic devices are increasing. is increasing significantly.

Liquid electrolytes used in lithium ion secondary batteries have high flammability, volatility, and safety problems against explosion due to leakage, and therefore, research and development of all-solid secondary batteries are being conducted using solid electrolytes instead of liquid electrolytes.

However, since the conventional all-solid-state secondary battery does not contain a liquid electrolyte, the all-solid electrode layer needs a component capable of conducting ion conduction.

In addition, since the solid electrolyte of the conventional all-solid-state secondary battery is composed of solid components, high contact resistance is generated at the interface between solids, that is, the contact surface between the solid electrolyte particles or the solid electrode layer and the solid electrolyte film. Therefore, compared to a secondary battery using a liquid electrolyte, high resistance occurs in an all-solid electrode, which adversely affects electrode performance.

An object of the present invention is to provide an all-solid-state electrode layer for effectively delivering lithium ions to the electrode.

In addition, an object of the present invention is to provide an all-solid electrode layer capable of minimizing resistance in the electrode and maximizing the lithium ion storage capacity of the active material.

In addition, an object of the present invention is to provide an all-solid-state electrode layer for improving the performance of an all-solid-state secondary battery.

An all-solid electrode layer according to the present invention for achieving the above object may include an ion diffusion-based electrode layer and a composite electrode layer laminated on the ion diffusion-based electrode layer and including a solid electrolyte and an active material.

According to the present invention, by forming different types of electrodes, it is possible to effectively conduct and diffuse ions to the electrodes to implement a high-output and high-capacity all-solid-state electrode.

In addition, the present invention can implement an all-solid-state electrode having optimal interfacial characteristics by using a carbon-based, metal-based, or sulfide-based material as an active material.

1 is a schematic cross-sectional view showing the structure of an all-solid-state secondary battery according to an embodiment of the present invention.
2 is a schematic cross-sectional view centering on a first all-solid-state electrode layer of an all-solid-state secondary battery according to an embodiment.
3 is a flowchart illustrating a process of manufacturing an all-solid-state electrode layer according to an embodiment.
4 is a SEM image showing a cross section of the all-solid electrode layer according to Example 1.
5 is an ESD image showing a cross section of an all-solid-state electrode layer according to Example 1;
6 is a SEM image showing a cross section of an all-solid electrode layer according to Example 2.
7 is an ESD image showing a cross section of an all-solid electrode layer according to Example 2;
8 is a graph showing charging and discharging results of an all-solid-state secondary battery having an all-solid-state electrode layer according to Example 1;
9 is a graph showing charging and discharging results of an all-solid-state secondary battery having an all-solid-state electrode layer according to Comparative Example 1;
10 is a graph showing charging and discharging results of an all-solid-state secondary battery having an all-solid-state electrode layer according to Comparative Example 2;
11 is a diagram comparing capacity per volume for Example 1 and Comparative Examples 1 and 2.
12 is a graph showing charging and discharging results of an all-solid-state secondary battery having an all-solid-state electrode layer according to Example 2;

Advantages and features of the present invention, and methods of achieving them, will become clear with reference to the detailed description of the following embodiments taken in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, only these embodiments make the disclosure of the present invention complete, and common knowledge in the art to which the present invention belongs. It is provided to fully inform the holder of the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numbers designate like elements throughout the specification.

Although "first" or "second" is used to describe various elements, these elements are not limited by the above terms. Such terms may only be used to distinguish one component from another. Therefore, the first component mentioned below may also be the second component within the technical spirit of the present invention.

Terms used in this specification are for describing embodiments and are not intended to limit the present invention. In this specification, singular forms also include plural forms unless specifically stated otherwise in a phrase. As used herein, "comprises" or "comprising" implies that a stated component or step does not preclude the presence or addition of one or more other components or steps.

Unless otherwise defined, all terms used herein may be interpreted as meanings commonly understood by those of ordinary skill in the art to which the present invention belongs. In addition, terms defined in commonly used dictionaries are not interpreted ideally or excessively unless explicitly specifically defined.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, and when describing with reference to the drawings, the same or corresponding components are given the same reference numerals, and overlapping descriptions thereof will be omitted. .

1 is a schematic cross-sectional view showing the structure of an all-solid-state secondary battery according to an embodiment of the present invention.

Referring to FIG. 1 , an all-solid secondary battery 1000 according to an embodiment includes a first current collector layer 100, a first all-solid electrode layer 200, a solid electrolyte layer 300, and a second all-solid An electrode layer 400 and a second current collector layer 500 may be included.

The first current collector layer 100 may transfer electrons to the outside. The first current collector layer 100 may maintain the entire skeleton of the all-solid-state secondary battery 1000 . The first current collector layer 100 may have high conductivity without causing chemical change of the all-solid-state secondary battery.

The first current collector layer 100 includes nickel (Ni), copper (Cu), gold (Au), aluminum (Al), iron (Fe), titanium (Ti), stainless steel, or fired carbon. can include Alternatively, as the first current collector layer 100, the surface of aluminum (Al) or stainless steel is treated with nickel (Ni), carbon (C), titanium (Ti), or silver (Ag) It can, but is not limited to this. The second current collector layer 500 may face the first current collector layer 100 . The material of the second current collector layer 500 may be the same as that of the first current collector layer 100 .

The first all-solid electrode layer 200 may be stacked on the first current collector layer 100 . The first all-solid electrode layer 200 may include an ion diffusion-based electrode layer 222 and a composite electrode layer 226 . The first all-solid-state electrode layer 200 may be an anode or a cathode. The second all-solid-state electrode layer 400 may face the first all-solid-state electrode layer 200 . The second all-solid electrode layer 400 may be a cathode or an anode. Structures of the first all-solid-state electrode layer 200 and the second all-solid-state electrode layer 400 will be described in detail later.

The solid electrolyte layer 300 may be disposed between the first all-solid electrode layer 200 and the second all-solid electrode layer 400 . The solid electrolyte layer 300 serves to transfer ions (eg, lithium ions) to the first all-solid electrode layer 200 and the second all-solid electrode layer 400 .

_1/3-2xTiO₃ (LLTO), Li_1+xTi_2-xM_x(PO₄)₃ (M=Al, Ga, In, Sc), 및 Li₇La₃Zr₂O₁₂(LLZO) 중 어느 하나를 포함할 수 있다. 할로겐계 소재는 Li₃ErX₆, Li₃GdX₆, Li₃YX₆, Li₃YX₆, 및 Li₃InCl₆ (X=I, Cl, Br) 중 어느 하나를 포함할 수 있다. 고분자계 소재는 젤 전해질 또는 고분자 전해질일 수 있고, 고분자 매트릭스 내에 해리된 리튬 염이 존재하는 형태일 수 있다. 고분자계 소재는 폴리테트라플루오로데틸렌(polytetrafluoroethylene), 폴리불화비닐리덴(polyvinylidene fluoride, PVdF), 폴리에틸렌옥사이드(poly(ethylene oxide)), 폴리아크리로나이트릴(polyacrylonitrile), 하이드로프로필 셀롤로오스(hydroxypropyl cellulose), 카복시메틸셀루로오스(Carboxymethyl cellulose), 스탈렌-부타디엔(Styrene-butadiene), 나이트릴-부타디엔(Nitrile-butadiene rubber), 폴리아크릴레이트(polyacrylate), 및 폴리아크릴릭애씨드(polyacrylic acid) 중 어느 하나를 포함할 수 있다. 리튬 염은 LiPF₆, LiBF₄, LiSbF₆, LiAsF₆, LiClO₄, LiN(C₂F₅SO₂)₂, LiN(CF₃SO₂)₂, CF₃SO₃Li, LiC(CF₃SO₂)₃, 및 LiC₄BO₈ 중 어느 하나를 포함할 수 있다. The solid electrolyte layer 300 may include a sulfide-based material, an oxide-based material, a halogen-based material, a polymer-based material, or a mixture thereof. Sulfide-based materials include Li _4-x Ge _1-x P _x S ₄ (LGPS), Li ₃ PS ₄ glass-ceramic, Li ₇ P ₃ S ₁₁ glass-ceramic (LPS), Li ₄ SnS ₄ , and Li ₆ P It may contain any one of ₅ SX (X=I, Br, Cl). Oxide-based materials are Li _3x La _2/3-x

_1/3-2x TiO ₃ (LLTO), Li _1+x Ti _2-x M _x (PO ₄ ) ₃ (M=Al, Ga, In, Sc), and Li ₇ La ₃ Zr ₂ O ₁₂ (LLZO) may include any one of them. The halogen-based material may include any one of Li ₃ ErX ₆ , Li ₃ GdX ₆ , Li ₃ YX ₆ , Li ₃ YX ₆ , and Li ₃ InCl ₆ (X=I, Cl, Br). The polymer-based material may be a gel electrolyte or a polymer electrolyte, and may have a form in which a dissociated lithium salt exists in a polymer matrix. Polymer-based materials include polytetrafluoroethylene, polyvinylidene fluoride (PVdF), poly(ethylene oxide), polyacrylonitrile, hydropropyl cellulose ( hydroxypropyl cellulose, carboxymethyl cellulose, styrene-butadiene, nitrile-butadiene rubber, polyacrylate, and polyacrylic acid may include any one of them. Lithium salts are LiPF ₆ , LiBF ₄ , LiSbF 6 , LiAsF ₆ , LiClO ₄ , LiN(C ₂ F ₅ SO ₂ ) ₂ , LiN(CF ₃ SO _{2 ) 2} , CF ₃ SO ₃ Li, LiC(CF ₃ SO ₂ ) ₃ , and LiC ₄ BO ₈ .

In order to improve the mechanical properties of the solid electrolyte layer 300, the solid electrolyte layer 300 may include a polymer binder or a polymer separator.

Meanwhile, the first all-solid electrode layer 200 and the second all-solid electrode layer 400 may conduct and diffuse ions transferred from the solid electrolyte layer 300 . At least one of the first all-solid-state electrode layer 200 and the second all-solid-state electrode layer 400 includes a stacked form of an ion diffusion-based electrode layer and a composite electrode layer proposed in the present invention, and the other is an ion diffusion-based electrode layer and a composite electrode layer. It may consist of an electrode layer or a metal layer. The metal layer is the same as the type of ion to be used, and lithium metal or a metal containing lithium metal may be used in a lithium ion-based all-solid-state secondary battery. In some cases, both the first all-solid-state electrode layer 200 and the second all-solid-state electrode layer 400 may be composed of the laminated electrode layers of the present invention.

2 is a schematic cross-sectional view centering on a first all-solid-state electrode layer of an all-solid-state secondary battery according to an embodiment.

Referring to FIG. 2 , the first all-solid-state electrode layer 200 according to the embodiment may include an ion diffusion-based electrode layer 222 and a composite electrode layer 226 .

The ion diffusion-based electrode layer 222 may be formed to contact the upper surface of the first current collector layer 100 . The composite electrode layer 226 may be formed to contact the lower surface of the solid electrolyte layer 300 .

The ion diffusion-based electrode layer 222 may include an active material 224 . As the active material 224 , an active material for a positive electrode or an active material for a negative electrode may be used. The active material 224 may be a carbon-based material, a metal-based material, a sulfide-based material, or a mixture thereof.

The embodiment enables movement of ions in the first all-solid-state electrode layer 200 by using a carbon-based material, a metal-based material, a sulfide-based material, or a mixture thereof as the active material 224, thereby improving the performance of the all-solid-state secondary battery 1000 can improve

Carbon-based materials may include natural graphite, artificial graphite, hard carbon, soft carbon, carbon nanotubes, carbon nanofibers, graphene, or maxene, but are not limited thereto. The metal-based material may include lithium, germanium, or tin, but is not limited thereto. Sulfide-based materials may include, but are not limited to, sulfur, molybdenum disulfide, titanium disulfide, or tungsten disulfide.

The ion diffusion-based electrode layer 222 may further include a polymer binder. The polymer binder may fix the active material and stably adhere to the first current collector layer 100 . The polymeric binder may include an aqueous or non-aqueous material. For example, polymeric binders include polytetrafluoroethylene, polyvinylidene fluoride (PVdF), poly(ethylene oxide), polyacrylonitrile, hydropropyl cell Hydroxypropyl cellulose, Carboxymethyl cellulose, Styrene-butadiene, Nitrile-butadiene rubber, polyacrylate, and polyacrylic acid ) may include at least one of them.

A weight ratio of the active material 224 of the ion diffusion-based electrode layer 222 to the polymer binder may be 80:20 to 100:0. That is, the weight of the polymer binder relative to the weight of the active material 224 may be less than 1/4 times. When the active material 224 is used as a material having excellent adhesion between particles, a polymer binder may not be used.

The ion diffusion-based electrode layer 222 may further include a conductive material. The conductive material may impart electronic conductivity to the first all-solid electrode layer 200 . The conductive material may include at least one of graphite, hard/soft carbon, carbon fiber, carbon nanotube, linear carbon, carbon black, acetylene black, and Ketjen Black, but is not limited thereto. The conductive material may be used within 5% of the weight of the first all-solid-state electrode layer 200 .

A composite electrode layer 226 may be deposited on the ion diffusion based electrode layer 222 . The composite electrode layer 226 may include a solid electrolyte 228 and an active material 224 .

The solid electrolyte 228 may have a particle structure connected to each other. The solid electrolyte 228 may contact the lower surface of the solid electrolyte layer 300 . The solid electrolyte 228 can effectively conduct ions of the solid electrolyte layer 300 .

_1/3-2xTiO₃ (LLTO), Li_1+xTi_2-xM_x(PO₄)₃ (M=Al, Ga, In, Sc), 및 Li₇La₃Zr₂O₁₂(LLZO) 중 어느 하나를 포함할 수 있다. 할로겐계 소재는 Li₃ErX₆, Li₃GdX₆, Li₃YX₆, Li₃YX₆, 및 Li₃InCl₆ (X=I, Cl, Br) 중 어느 하나를 포함할 수 있다. 고분자계 소재는 젤 전해질 또는 고분자 전해질일 수 있고, 고분자 매트릭스 내에 해리된 리튬 염이 존재하는 형태일 수 있다. 고분자계 소재는 폴리테트라플루오로데틸렌(polytetrafluoroethylene), 폴리불화비닐리덴(polyvinylidene fluoride, PVdF), 폴리에틸렌옥사이드(poly(ethylene oxide)), 폴리아크리로나이트릴(polyacrylonitrile), 하이드로프로필 셀롤로오스(hydroxypropyl cellulose), 카복시메틸셀루로오스(Carboxymethyl cellulose), 스탈렌-부타디엔(Styrene-butadiene), 나이트릴-부타디엔(Nitrile-butadiene rubber), 폴리아크릴레이트(polyacrylate), 및 폴리아크릴릭애씨드(polyacrylic acid) 중 어느 하나를 포함할 수 있다.The solid electrolyte 228 may include a sulfide-based material, an oxide-based material, a halogen-based material, a polymer-based material, or a mixture thereof. Sulfide-based materials include Li _4-x Ge _1-x P _x S ₄ (LGPS), Li ₃ PS ₄ glass-ceramic, Li ₇ P ₃ S ₁₁ glass-ceramic (LPS), Li ₄ SnS ₄ , and Li ₆ P It may contain any one of ₅ SX (X=I, Br, Cl). Oxide-based materials are Li _3x La _2/3-x

_1/3-2x TiO ₃ (LLTO), Li _1+x Ti _2-x M _x (PO ₄ ) ₃ (M=Al, Ga, In, Sc), and Li ₇ La ₃ Zr ₂ O ₁₂ (LLZO) may include any one of them. The halogen-based material may include any one of Li ₃ ErX ₆ , Li ₃ GdX ₆ , Li ₃ YX ₆ , Li ₃ YX ₆ , and Li ₃ InCl ₆ (X=I, Cl, Br). The polymer-based material may be a gel electrolyte or a polymer electrolyte, and may have a form in which a dissociated lithium salt exists in a polymer matrix. Polymer-based materials include polytetrafluoroethylene, polyvinylidene fluoride (PVdF), poly(ethylene oxide), polyacrylonitrile, hydropropyl cellulose ( hydroxypropyl cellulose, carboxymethyl cellulose, styrene-butadiene, nitrile-butadiene rubber, polyacrylate, and polyacrylic acid may include any one of them.

The active material 224 may be formed in a space between the solid electrolytes 228 . As the active material 224 , an active material utilized in a lithium ion secondary battery may be used. For example, the active material 224 includes natural graphite, artificial graphite, Li ₄ Ti ₅ O ₁₂ , hard carbon, silicon/carbon composite, silicon, lithium metal, LiCoO ₂ , LiFePO ₄ , LiMn ₂ O ₄ , Li ₂ MnO ₃ , LiNi _x Mn _y Co _z O ₂ (x+y+z=1) or LiNiCoAlO ₂ .

A weight ratio of the solid electrolyte 228 and the active material 224 in the composite electrode layer 226 may range from 50:50 to 5:95. That is, the weight of the active material 224 compared to the weight of the solid electrolyte 228 may be 1 to 19 times.

A polymer binder and a conductive material may be further included in the composite electrode layer 226 . The polymer binder and the conductive material may each be used within 5% based on the weight of the first all-solid-state electrode layer 200 .

Materials of the polymer binder and conductive material used in the composite electrode layer 226 may be the same as those of the polymer binder and conductive material used in the ion diffusion-based electrode layer 222 .

The first all-solid-state electrode layer 200 according to the embodiment may be manufactured as follows. Since the manufacturing process of the second all-solid-state electrode layer 400 is the same as the manufacturing method of the first all-solid-state electrode layer 200, the manufacturing process of the second all-solid-state electrode layer 400 will be omitted.

3 is a flowchart illustrating a process of manufacturing an all-solid-state electrode layer according to an embodiment.

2 and 3, the manufacturing method of the all-solid-state electrode layer according to the embodiment includes forming an ion diffusion-based electrode layer on a current collector layer (S100), pressing the ion diffusion-based electrode layer (S200), Forming a composite electrode layer on the ion diffusion-based electrode layer (S300) and pressing the divorced diffusion-based electrode layer and the composite electrode layer (S400) may be included.

First, a slurry may be prepared using the active material 224, a polymer binder, a solvent, and a conductive material. The content of the active material 224 and the polymer binder in the slurry may be 80:20 to 100:0 based on a weight ratio. That is, the weight of the polymer binder relative to the weight of the active material 224 may be less than 1/4 times. When the content of the active material 224 is high, there is an effect of enabling high energy density. Here, the viscosity of the slurry may be adjusted by the amount of the solvent, and may be selected from 100 cP to 10000 cP.

An ion diffusion-based electrode layer 222 may be formed by applying the slurry formed as described above on the first current collector layer 100 . After the formation of the ion diffusion-based electrode layer 222 is finished, hot air drying or vacuum drying may be performed at 50 degrees to 100 degrees to remove the solvent remaining in the ion diffusion-based electrode layer 222 .

When the ion diffusion-based electrode layer 222 is formed on the first current collecting layer 100, the step of pressing the ion diffusion-based electrode layer 222 (S200) may be performed. In step S200, particles of the active material 224 may be intimately bonded. Here, the pressure for pressing the ion diffusion-based electrode layer 222 may be 100 MPa to 700 MPa, and a pressure of 300 MPa to 600 MPa may be applied. Here, the step of pressing the ion diffusion-based electrode layer 222 ( S200 ) may be omitted in some cases.

Next, forming the composite electrode layer 226 on the ion diffusion-based electrode layer 222 (S300) may be performed. First, it may be prepared by mixing the solid electrolyte 228 and the active material 224. Additionally, a polymer binder, a solvent, and a conductive material may be further included. The weight ratio of the solid electrolyte 228 and the active material 224 may include 50:50 to 5:95. That is, the weight of the active material 224 compared to the weight of the solid electrolyte 228 may be 1 to 19 times. A polymer binder and a conductive material may be used within 5% of each based on the total weight of the electrode. The solvent may be adjusted to adjust the viscosity of the slurry in the same way as in the ion diffusion-based electrode layer preparation method.

When an oxide-based material is used as the solid electrolyte 228, since the interface resistance is high between the solid electrolyte 228 and the active material 224, the interface resistance can be reduced by performing a heat treatment process after manufacturing the composite electrode layer 226. there is. The heat treatment process may be performed by selecting from 200 degrees to 1000 degrees.

Subsequently, a step ( S400 ) of pressing the ion diffusion-based electrode layer 222 and the composite electrode layer 226 may be performed. A pressure for pressing the ion diffusion-based electrode layer 222 and the composite electrode layer 226 may be 100 MPa to 700 MPa, and a pressure of 300 MPa to 600 MPa may be applied.

In step S400, close interfaces can be formed between the active materials 224, between the active materials 224 and the solid electrolyte 228, and between the solid electrolytes 228, so that ions can move smoothly.

When step S400 is completed as described above, manufacturing of the first all-solid-state electrode layer 200 according to the embodiment may be completed.

Hereinafter, characteristics of the all-solid-state electrode layer according to the embodiment and the all-solid-state electrode layer according to the comparative example are compared.

[Example 1]

In Example 1, an all-solid electrode layer was prepared based on a graphite active material. Polyvinylidene fluoride dissolved in 10 wt% of methylpyrrolidone was used as a polymer binder for the ion diffusion-based electrode layer. Graphite/polyvinylidene fluoride in the slurry consisted of 98:2 by weight.

In addition, for uniform mixing of the slurry, it was mixed for 20 minutes at 1500 rpm through a defoaming mixer (Planetary Mixer). Here, the solvent methylpyrrolidone was additionally added to adjust the viscosity of the slurry, and the viscosity of the slurry was 500 cP.

The thickness of the ion diffusion-based electrode layer was adjusted through the application thickness of the doctor blade, and the methylpyrrolidone solvent was removed through 100 degree hot air drying. After that, a slurry coating process for preparing a composite electrode layer was performed on the ion diffusion-based electrode layer. The slurry for preparing the composite electrode layer was composed of graphite/Li ₆ PS ₅ Cl/nitrile-butadiene in a weight ratio of 59:39:2. Xylene was used as the solvent. The composite electrode layer used the same coating method as that of the ion diffusion-based electrode layer. The theoretical capacities per area of the ion diffusion-based electrode layer and the composite electrode layer in the all-solid electrode layer were 2.32 and 2.04 mAh/cm ² , respectively, and the theoretical capacities per total area were 4.36 mAh/cm ² . For intimate interfacial contact between the active materials, the pressure was applied at 400 MPa.

4 is an SEM image showing a cross-section of an all-solid-state electrode layer according to an embodiment, and FIG. 5 is an EDS image showing a cross-section of an all-solid-state electrode layer according to an embodiment.

As shown in FIG. 4 , it can be confirmed that the all-solid electrode layer 200 is composed of two layers. In addition, as shown in FIG. 5, it can be seen that C, P, S, and Cl, which are constituent elements of the solid electrolyte and the active material, are evenly detected in the composite electrode layer of the all-solid electrode layer 200. In addition, it can be seen that only C, a constituent element of the active material, was detected in the ion diffusion-based electrode layer.

To analyze charge/discharge characteristics, half cells were prepared. Li ₆ PS ₅ Cl was used as the solid electrolyte layer of the half cell. That is, after uniformly dispersing the Li ₆ PS ₅ Cl particles, they were pressurized at 400 MPa to form pellets. Then, after attaching the all-solid electrode layer of Example to one side of the solid electrolyte layer, it was integrated by pressing at 400 MPa. On the opposite side of the solid electrolyte layer, 300 μm of lithium metal was used as a counter electrode.

반쪽 전지를 구동하여 충방전 결과를 측정하였다. 방전 조건은 정전류(constant current)/정전압(constant voltage) 조건으로 실시되었으며, 비교예와 동일한 방전 조건을 위해 정전압 과정은 정전류에서 소요되는 시간 대비 1/10 시간만 허용하여 진행되었다. 예를 들면, 10시간의 방전이 예상되는 0.1C-rate의 충방전율에서는 1시간 동안만 정전압 과정이 진행되었다. 충전 조건은 정전류 기반으로 2V까지 진행하는 것으로 하였다. 흑연의 이론용량인 372mAh/g을 기준으로 0.1C-rate의 충방전율, 1C-rate의 충방전율에서 각각 3회 평가를 진행하였다. For the electrode layer performance evaluation, the cut-off voltage was adjusted to 0.01V and 2V. In addition, 60

The half cell was driven to measure the charge/discharge result. The discharge condition was performed under a constant current/constant voltage condition, and for the same discharge condition as the comparative example, the constant voltage process was performed by allowing only 1/10 of the time required for the constant current. For example, at a charge/discharge rate of 0.1 C-rate where a discharge of 10 hours is expected, a constant voltage process was performed for only 1 hour. The charging condition was to proceed up to 2V based on a constant current. Based on the theoretical capacity of graphite, 372mAh/g, evaluation was conducted three times at a charge/discharge rate of 0.1C-rate and a charge/discharge rate of 1C-rate, respectively.

[Comparative Example 1]

In Comparative Example 1, a composite electrode layer having a theoretical capacity per area of 3.98 mAh/cm ² was prepared. The manufacturing method of the composite electrode layer was performed in the same manner as the manufacturing method of the composite electrode layer in Example 1, and the charge/discharge evaluation was conducted under the same conditions as in Example 1.

[Comparative Example 2]

In Comparative Example 2, an ion diffusion-based electrode layer having a theoretical capacity per area of 4.20 mAh/cm ² was prepared. The manufacturing method of the ion diffusion-based electrode layer is the same as the manufacturing method of the ion diffusion-based electrode layer of Example 1, and the charge/discharge evaluation was performed under the same conditions as in Example 1.

[Example 2]

In Example 2, a composite electrode layer was prepared based on silicon and graphite active materials. Silicon is a material having a high theoretical capacity of 3579 mAh/g, and is advantageous for realizing a high-density secondary battery. An ion diffusion-based electrode layer was prepared in the same manner as in Example 1, and a silicon active material was used for the composite electrode layer. The slurry for preparing the composite electrode layer was composed of silicon/Li ₆ PS ₅ Cl/nitrile-butadiene in a weight ratio of 49:49:2, and was applied on the ion diffusion-based electrode layer in the same manner as in Example 1. The theoretical capacities per area of the ion diffusion-based electrode layer and the composite electrode layer in the prepared all-solid electrode layer were 2.42 and 5.53 mAh/cm ² , respectively, and the theoretical capacities per total area were 6.26 mAh/cm ² . For intimate interfacial contact between the active materials, the pressure was applied at 400 MPa.

6 is an SEM image showing a cross section of an all-solid-state electrode layer according to Example 2, and FIG. 7 is an EDS image showing a cross section of the all-solid-state electrode layer according to Example 2.

As shown in FIG. 6, it can be confirmed that the all-solid electrode layer according to Example 2 is composed of two layers. In addition, as shown in FIG. 7, it can be seen that Si and C are separated and distributed like the all-solid electrode layer of Example 1.

8 is a graph showing the charging and discharging results of an all-solid-state secondary battery having an all-solid-state electrode layer according to Example 1, and FIG. 9 is a graph showing the charging and discharging results of an all-solid-state secondary battery having an all-solid-state electrode layer according to Comparative Example 1. 10 is a graph showing the charging and discharging results of an all-solid-state secondary battery having an all-solid-state electrode layer according to Comparative Example 2, and FIG. 11 is a comparison of capacity per volume for Example 1 and Comparative Examples 1 and 2. FIG. 12 is a graph showing charging and discharging results of an all-solid-state secondary battery having an all-solid-state electrode layer according to Example 2.

As shown in FIGS. 8 to 10 , as a result of the charge/discharge evaluation of the charge/discharge rate of 0.1 C-rate in Example 1, Comparative Example 1, and Comparative Example 2, it can be seen that all of them implemented a capacity of 300 mAh/g or more. The all-solid-state electrode layer of Example 1 realized a capacity of 350 mAh/g or more despite a high loading amount.

As shown in FIG. 11, the implemented capacity per volume of Example 1, Comparative Example 1, and Comparative Example 2 is the all-solid electrode layer of Example 1 in which the ion diffusion-based electrode layer and the composite electrode layer are laminated at a charge/discharge rate of 0.1 C-rate. At 529.1mAh/cm ³ , it is slightly lower than the 562.7mAh/cm ³ of the ion diffusion-based electrode layer, but at a charge/discharge rate of 1C-rate, the all-solid-state electrode layer implements 308.8mAh/cm ³ , compared to other electrode layers (composite electrode layer: 237.3mAh/cm). ³ , ion diffusion-based electrode layer: 231.7mAh/cm ³ ) showed excellent performance. Through this, in the case of the all-solid-state electrode layer of Example 1, it can be confirmed that high performance can be implemented compared to the composite electrode at low rate charging and discharging, and excellent output characteristics can be exhibited compared to other electrode structures at high rate charging and discharging.

As shown in FIG. 12 , in the case of Example 2, it was possible to realize a higher area capacity by using silicon having a high theoretical capacity for the composite electrode layer. As can be seen in FIG. 13, an area capacity of 5.83 mAh/cm ² was implemented, and when converted to the electrode thickness of FIG. 11, it can be seen that this corresponds to a capacity per volume of 1300 mAh/cm ³ .

As described above, the all-solid-state electrode layer according to the present invention is not limited to the configuration and method of the embodiments described above, but all or part of each embodiment so that various modifications can be made in the above embodiments. May be configured by selectively combining.

100: first collector layer
200: first all-solid electrode layer
222: ion diffusion based electrode layer
226: composite electrode layer
300: solid electrolyte layer
400: second all-solid electrode layer
500: second collector layer

Claims (1)

an ion diffusion based electrode layer; and
a composite electrode layer laminated on the ion diffusion-based electrode layer and including a solid electrolyte and an active material;
All-solid electrode layer comprising a.

Images