KR20220067639A - All-solid-state secondary battery - Google Patents

Abstract

The present invention relates to an all-solid-state secondary battery and, more specifically, to an all-solid-state secondary battery including a positive electrode, a negative electrode, and a solid electrolyte layer disposed between the positive electrode and the negative electrode, wherein at least one of the positive electrode and the negative electrode includes a one-dimensional solid electrolyte material, an electrode active material and a binder, the aspect ratio of the one-dimensional solid electrolyte material is 20 to 1000, and the content of the one-dimensional solid electrolyte material can be 5 to 20 wt% based on the weight of the at least one of the positive electrode and the negative electrode.

Description

All-solid-state secondary battery {ALL-SOLID-STATE SECONDARY BATTERY}

The present invention relates to an all-solid-state secondary battery with improved capacity and stability.

A lithium secondary battery has a high energy density compared to other batteries, and can be small and lightweight, so it has a high possibility of being used as a power source for portable electronic devices and the like. A lithium secondary battery may include a positive electrode, a negative electrode, and an electrolyte. In general, a carbonate-based solvent in which lithium salt (LiPF ₆ ) is dissolved as a liquid electrolyte is widely used. Liquid electrolyte exhibits excellent electrochemical properties due to high mobility of lithium ions, but has problems in safety due to explosion due to high flammability, volatility, and leakage.

Accordingly, research on an All-Solid-State Secondary Battery using a solid electrolyte instead of a liquid electrolyte is being conducted. Since the all-solid-state secondary battery can secure stability and mechanical strength, it is attracting attention in various application systems requiring high safety, such as electric vehicles, energy storage systems, and wearable devices.

One technical problem to be solved by the present invention is to provide an all-solid-state secondary battery with improved capacity and stability.

The problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

An all-solid-state secondary battery according to an embodiment of the present invention includes a positive electrode, a negative electrode, and a solid electrolyte layer disposed between the positive electrode and the negative electrode, wherein at least one of the positive electrode and the negative electrode is a one-dimensional solid electrolyte material, an electrode an active material and a binder, wherein an aspect ratio of the one-dimensional solid electrolyte material is 20 to 1000, and the content of the one-dimensional solid electrolyte material is 5 wt% to 20 wt% based on the weight of at least one of the positive electrode and the negative electrode It can be %.

In the all-solid-state secondary battery according to the present invention, the one-dimensional solid electrolyte material has a relatively advantageous interface formation with the electrode active material even with a small content due to one-dimensional structural characteristics, and the free volume is large, so that the composite electrode During formation, aggregation between solid electrolytes is suppressed, so that the ion transport network can be easily formed. In addition, since the contact area with the electrode active material is increased, the interface resistance can be minimized. That is, even if a small amount of the one-dimensional solid electrolyte material is included, an ion path in the electrode may be secured. Accordingly, the content of the electrode active material in the electrode can be maximized, and finally, an all-solid-state secondary battery having a high energy density can be realized.

1 is a cross-sectional view showing an all-solid-state secondary battery according to an embodiment of the present invention.
2 is a schematic view of the inside of an electrode for an all-solid-state secondary battery according to an embodiment of the present invention.
3 shows the SEM shape analysis result of the one-dimensional solid electrolyte material included in the electrode for an all-solid-state secondary battery.
4 shows an EDS-mapping analysis result of a cross-sectional structure of an electrode for an all-solid-state secondary battery manufactured according to an embodiment of the present invention.
5A to 5C show the results of EDS-mapping analysis of the cross-sectional structures of electrodes for all-solid-state secondary batteries prepared according to Comparative Examples.
6 shows the results of charging and discharging of the all-solid-state secondary battery manufactured according to an embodiment of the present invention.
7 shows the charging and discharging results of the all-solid-state secondary battery prepared according to the comparative example.
8 shows the lifespan characteristics of the all-solid-state secondary battery manufactured according to an embodiment of the present invention.
9 shows the lifespan characteristics of the all-solid-state secondary battery manufactured according to the comparative example.

Advantages and features of the present invention, and methods for achieving them, will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only this embodiment serves to complete the disclosure of the present invention, and to obtain common knowledge in the technical field to which the present invention pertains. It is provided to fully inform the possessor of the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout.

The terminology used herein is for the purpose of describing the embodiments and is not intended to limit the present invention. In this specification, the singular also includes the plural unless specifically stated otherwise in the phrase. As used herein, 'comprises' and/or 'comprising' means that a referenced component, step, operation and/or element is the presence of one or more other components, steps, operations and/or elements. or addition is not excluded.

Further, the embodiments described herein will be described with reference to cross-sectional and/or plan views, which are ideal illustrative views of the present invention. In the drawings, thicknesses of films and regions are exaggerated for effective description of technical content. Accordingly, the shape of the illustrative drawing may be modified due to manufacturing technology and/or tolerance. Accordingly, the embodiments of the present invention are not limited to the specific form shown, but also include changes in the form generated according to the manufacturing process. Accordingly, the regions illustrated in the drawings have a schematic nature, and the shapes of the illustrated regions in the drawings are intended to illustrate specific shapes of regions of the device and not to limit the scope of the invention.

Unless otherwise defined, terms used in the embodiments of the present invention may be interpreted as meanings commonly known to those of ordinary skill in the art.

Hereinafter, in order to describe the present invention in more detail, embodiments according to the present invention will be described in more detail with reference to the accompanying drawings.

1 is a cross-sectional view showing an all-solid-state secondary battery according to an embodiment of the present invention. 2 is a schematic diagram of an electrode for an all-solid-state secondary battery according to an embodiment of the present invention.

1 and 2 , the all-solid-state secondary battery 10 may include a current collector 100 , a positive electrode 201 , a negative electrode 202 , and a solid electrolyte layer 300 .

The two current collectors 100 may be disposed to face each other. A positive electrode 201 and a negative electrode 202 may be disposed on one surface of each of the current collectors 100 . The anode 201 and the cathode 202 may be disposed to face each other. The solid electrolyte layer 300 may be interposed between the positive electrode 201 and the negative electrode 202 . In this specification, the electrode may refer to the anode 201 or the cathode 202 .

The current collector 100 may transfer electrons to the outside and maintain the entire skeleton of the all-solid-state secondary battery 10 . The current collector 100 may include a metal having high conductivity and high oxidation stability without causing a chemical change in the all-solid-state secondary battery 10 . For example, the current collector 100 may include nickel (Ni), copper (Cu), gold (Au), aluminum (Al), iron (Fe), titanium (Ti), stainless steel, and sintering. It may include at least one of carbon. As another example, the current collector 100 is formed by treating the surface of aluminum (Al) or stainless steel with at least one of nickel (Ni), carbon (C), titanium (Ti), and silver (Ag). may include

The positive electrode 201 and the negative electrode 202 may include a one-dimensional solid electrolyte material 210 , an electrode active material 220 , and a polymeric binder. The one-dimensional solid electrolyte material 210 may have a one-dimensional shape. The one-dimensional solid electrolyte material 210 may have an aspect ratio of 20 to 1000, preferably 20 to 100. In the present specification, the aspect ratio may mean a value (L/D) obtained by dividing the length (L) by the diameter (D) when the length is L and the diameter is D. The content of the one-dimensional solid electrolyte material 210 may be 5 wt% to 20 wt% based on the weight of at least one of the positive electrode 201 and the negative electrode 202 . In detail, the content of the one-dimensional solid electrolyte material 210 in the positive electrode 201 may be 5 wt% to 20 wt% based on the weight of the positive electrode 201 . The content of the one-dimensional solid electrolyte material 210 in the negative electrode 202 may be 5 wt% to 20 wt% based on the weight of the negative electrode 202 . When the one-dimensional solid electrolyte material 210 is 5 wt% or less based on the weight of each of the positive electrode 201 and the negative electrode 202, it may be difficult to form ion conduction percolation, that is, to form an ion connection network, and the positive electrode 201 ) and 20 wt% or more based on the weight of each of the anodes 202, local aggregation may occur, which may result in inhibition of electron transport and reduction in electrode energy density. According to the present invention, the one-dimensional solid electrolyte material 210 has a relatively advantageous interface formation with the electrode active material 220 even with a small content due to the one-dimensional structural characteristics, and the free volume is large, so that the composite The aggregation phenomenon between solid electrolytes is suppressed during electrode formation, so that the ion transport path (arrow in FIG. 2) can be easily formed. In addition, since the contact area with the electrode active material is increased, the interface resistance can be minimized. That is, even if a small amount of the one-dimensional solid electrolyte material 210 is included, an ion transfer path (arrow in FIG. 2 ) within the electrode may be secured. Accordingly, the content of the electrode active material 220 in the electrode can be maximized, so that the all-solid-state secondary battery 10 having a high energy density can be finally realized.

For example, the one-dimensional solid electrolyte material 210 may include at least one of an oxide-based material, a phosphate-based material, and a sulfide-based material. For example, the oxide-based material may include at least one of Li ₅ La ₃ M ₂ O ₁₂ (M=Nb, Ta), Li ₇ La ₃ ZrO ₁₂ , and Li ₆ BaLa ₂ Ta ₂ O ₁₂ garnet-type material. may include In addition, with respect to Li ₇ La ₃ Zr ₂ O ₁₂ , Al, Ga, etc. are doped into the Li site as doping elements (0 to 0.3 mol ratio), and Nb, Ta, etc. It may contain one substance. In another example, the oxide-based material is a perovskite of Li _3x La _(2/3)-x □ _(1/3)-2x TiO ₃ (LLTO, 0<x<0.16, □: vacancy). ) structure. The phosphate-based material may include a material having a NAISICON structure of Li _1+x Al _x Ti _2-x (PO ₄ ) ₃ (x=0 to 0.4). The sulfide-based material is Li _10±1 MP ₂ X ₁₂ (M=Ge, Si, Sn, Al or P, and X=S or Se) (eg, Li ₁₀ SnP ₂ S ₁₂ , or Li _4-x Sn _1-x As _x S ₄ (x=0~100)), thio-lithium superionic conductor (thio-LISICON) (eg, Li _3.25 Ge _0.25 P _0.75 S ₄ , or Li ₁₀ GeP ₂ S ₁₂ ), Li -argyrodite Li ₆ PS ₅ X (X=Cl, Br or I) (eg, Li ₆ PS ₅ Cl), glass-ceramic structure Li ₂ S·P ₂ S ₅ (xLi ₂ S ·(100-x)P ₂ S ₅ , x=0 to 100), a material having a glassy structure including a chalcogenide element and lithium (eg, Li ₂ ·P ₂ S ₅ , Li ₂ S·SiS ₂ ·Li ₃ N, Li ₂ S·P ₂ S ₅ ·LiI, Li ₂ S·SiS ₂ ·Li _x MO _y , Li ₂ S·GeS ₂ , Li ₂ S·B ₂ S ₃ ·LiI) may include

The electrode active material 220 may serve to store lithium (Li) ions or sodium (Na) ions. The electrode active material 220 may include an active material for a positive electrode used for the positive electrode 201 or an active material for a negative electrode used for the negative electrode 202 . The electrode active material 220 may include a material capable of being mechanically deformed, ie, deformed in shape under a pressurized condition. For example, the active material for the positive electrode is lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), lithium manganese oxide (LiMnO ₄ ), lithium nickel cobalt aluminum oxide (LiNiCoAlO ₂ ), olivine (LiFePO ₄ ), and lithium cobalt manganese nickel oxide (LiCo _x Mn _y Ni _z O ₂ ; x+y+z=1). For example, the active material for the negative electrode may include at least one of a carbon-based active material, a non-carbon-based active material, and a metal-containing active material. For example, the carbon-based active material may include at least one of graphite, hard carbon, soft carbon, graphene, and a carbon nanotube composite. For example, the non-carbon-based active material may include at least one of tin, silicon, lithium titanium oxide (Li _x TiO ₂ ), and spinel lithium titanium oxide (Li ₄ Ti ₅ O ₁₂ ). For example, the metal-containing active material may include at least one of a lithium metal foil, a lithium metal powder, a sodium metal foil, and a sodium metal powder. The content of the electrode active material 220 in the positive electrode 201 may be 70 wt% to 93 wt%, or 80 wt% to 93 wt%, based on the weight of the positive electrode 201 . The content of the electrode active material 220 in the negative electrode 202 may be 76 wt% to 93 wt%, or 80 wt% to 93 wt%, based on the weight of the negative electrode 202 .

The binder (polymeric binder) may serve to maintain the mechanical stability of the all-solid-state secondary battery 10 by fixing the electrode active material 220 . The binder may include an aqueous or non-aqueous material. For example, the binder is polyvinylidene fluoride (polyvinylidene fluoride), polyimide (polyimide), polytetrafluoroethylene (polytetrafluoroethylene), polyethylene oxide (poly (ethylene oxide)), polyacrylonitrile (polyacrylonitrile) , hydroxypropyl cellulose, carboxymethyl cellulose, sodium carboxymethyl cellulose, styrene-butadiene rubber, and nitrile-butadiene rubber ) may include at least one of. The content of the binder in the positive electrode 201 may be 1 wt% to 5 wt% based on the weight of the positive electrode 201 . The content of the binder in the negative electrode 202 may be 1 wt% to 2 wt% based on the weight of the negative electrode 202 .

At least one of the anode 201 and the cathode 202 may further include an electro-conducting agent. The conductive material may serve to impart electron conductivity to each of the anode 201 and the cathode 202 . The conductive material may include a material having conductivity. For example, 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. For example, when the conductivity of the electrode active material 220 is 100 S/cm (at 20° C.) or less, the content of the conductive material in the positive electrode 201 is 1 wt% to 1 wt% of the weight of the positive electrode 201 5 wt %. For example, when the conductivity of the electrode active material 220 is 100 S/cm (at 20° C.) or less, the content of the conductive material in the negative electrode 202 is 1 wt% to the weight of the negative electrode 202 2 wt%. However, in some embodiments, the positive electrode 201 and the negative electrode 202 may not include a conductive material. For example, when the conductivity of the electrode active material 220 is 100 S/cm (at 20° C.) or more, the positive electrode 201 may not include a conductive material.

The solid electrolyte layer 300 may serve to transfer ions to the positive electrode 201 and the negative electrode 202 . The solid electrolyte layer 300 may include the one-dimensional solid electrolyte material 210 . For example, the one-dimensional solid electrolyte material 210 may include at least one of an oxide-based material, a phosphate-based material, and a sulfide-based material. For example, the oxide-based material may include at least one of Li ₅ La ₃ M ₂ O ₁₂ (M=Nb, Ta), Li ₇ La ₃ ZrO ₁₂ , and Li ₆ BaLa ₂ Ta ₂ O ₁₂ garnet-type material. may include In addition, with respect to Li ₇ La ₃ Zr ₂ O ₁₂ , Al, Ga, etc. are doped into the Li site as doping elements (0 to 0.3 mol ratio), and Nb, Ta, etc. It may contain one substance. In another example, the oxide-based material is a perovskite of Li _3x La _(2/3)-x □ _(1/3)-2x TiO ₃ (LLTO, 0<x<0.16, □: vacancy). ) structure. The phosphate-based material may include a material having a NAISICON structure of Li _1+x Al _x Ti _2-x (PO ₄ ) ₃ (x=0 to 0.4). The sulfide-based material is Li _10±1 MP ₂ X ₁₂ (M=Ge, Si, Sn, Al or P, and X=S or Se) (eg, Li ₁₀ SnP ₂ S ₁₂ , or Li _4-x Sn _1-x As _x S ₄ (x=0~100)), thio-lithium superionic conductor (thio-LISICON) (eg, Li _3.25 Ge _0.25 P _0.75 S ₄ , or Li ₁₀ GeP ₂ S ₁₂ ), Li -argyrodite Li ₆ PS ₅ X (X=Cl, Br or I) (eg, Li ₆ PS ₅ Cl), glass-ceramic structure Li ₂ SP ₂ S ₅ (xLi ₂ S(100) -x)P ₂ S ₅ , x=0 to 100), a material having a glassy structure including a chalcogenide element and lithium (eg, Li ₂ P ₂ S ₅ , Li ₂ SSiS ₂ Li ₃ N, Li ₂ SP ₂ S ₅ LiI, Li ₂ SSiS ₂ Li _x MO _y , Li ₂ SGeS ₂ , Li ₂ SB ₂ S ₃ LiI).

Referring again to FIG. 1 , a method of manufacturing the all-solid-state secondary battery 10 according to an embodiment of the present invention will be described.

The one-dimensional solid electrolyte material 210 may be manufactured using a sacrificial template. Specifically, a sacrificial template may be provided. The sacrificial template may be a polymer having a one-dimensional shape. The polymer constituting the sacrificial template may be a polymer that is decomposed at about 200 °C to 700 °C. After performing a process of injecting the solid electrolyte components into the sacrificial template, or binding the solid electrolyte components to the sacrificial template surface and performing a heat treatment process, the sacrificial template is removed to prepare the one-dimensional solid electrolyte material 210 . . In this case, the one-dimensional solid electrolyte material 210 may have a sacrificial template shape.

More specifically, the process of injecting the solid electrolyte components into the sacrificial template may include dissolving precursors constituting the solid electrolyte in a solvent to prepare a precursor solution. Thereafter, the precursor solution is stirred in a polymer solution, molded into a one-dimensional shape, and then a heat treatment process is performed to decompose the polymer to prepare the one-dimensional solid electrolyte material 210 . More specifically, in the process of binding the solid electrolyte components to the sacrificial template surface and then heat-treating, the precursors constituting the solid electrolyte are dissolved in an aqueous solution so that the components exist as (+) or (-) ions in the solution. may include doing After that, the one-dimensional solid electrolyte material 210 is produced by binding the polymer material having a surface modified to (+) or (-) through an electrostatic attraction reaction, and decomposing the polymer by performing a heat treatment process. may include

Manufacturing the positive electrode 201 or the negative electrode 202 may include performing a slurry-based thick film coating process. More specifically, the prepared one-dimensional solid electrolyte material 210, the electrode active material 220, and a conductive material may be added, and a mechanical mixing process may be performed to make the composite. Thereafter, a binder solution in which the binder is dissolved may be added, and a stirring process may be performed to prepare an electrode slurry. Thereafter, the electrode slurry is applied to a metal foil and a drying process is performed to remove the solvent in the binder solution, and then a pressing process is performed to manufacture the positive electrode 201 or the negative electrode 202 electrode plate. By controlling the viscosity of the electrode slurry, the coating thickness, and the pressure during the compression process, the loading level (loading level = active material content/area) can be adjusted. The higher the viscosity of the electrode slurry, the thicker the coating, and the greater the pressure during the compression process, the higher the loading level may be. For example, the pressure during the compression process may be 100 mPa to 400 mPa. For example, the thickness of the electrode may be 1 um to 300 um.

Manufacturing the composite electrode-based all-solid-state secondary battery 10 includes forming the solid electrolyte layer 300 by performing a cold or hot sintering process, and a positive electrode 201 and a negative electrode 202 manufactured through a slurry application process. ) forming an electrode on both surfaces of the solid electrolyte layer 300, and applying a pressure of 100 MPa to 200 MPa to form a close interface between the solid electrolyte layer 300 and the positive electrode 201 and the negative electrode 202, respectively may include doing The charge/discharge characteristics of the prepared all-solid-state secondary battery 10 may be measured at 0 °C to 150 °C. That is, the all-solid-state secondary battery 10 according to the present invention may be driven at 0 °C to 150 °C.

Example

A slurry-based coating process was performed to prepare a composite anode including natural graphite/1dimensional solid electrolyte/binder in a ratio of 80:15:5. The one-dimensional solid electrolyte material was prepared by performing an electrospinning method.

Specifically, a polymer solution was prepared by dissolving PVP (polyvinylpyrrolidone) in ethanol at 15 wt%. After that, LiNO ₃ , La(NO ₃ ) ₃ ·6H ₂ O, ZrOCl ₂ ·8H ₂ O raw materials are dissolved in a solution of ethanol:water (80:20, weight ratio) at a concentration of 1mmol according to the stoichiometric ratio. made it At this time, Al(NO ₃ ) ₃ ·9H ₂ O was dissolved together at a ratio of 1.2 wt%. A precursor solution was prepared by mixing and stirring the polymer solution and the solid electrolyte component solution in a volume ratio of 6:4. 1 mL of the precursor solution was placed in a syringe and a constant pressure was applied to flow out through the nozzle at a rate of 0.03 ml/min. At this time, a voltage of 18 kV was applied between the nozzle and the collector to generate nanofibers from the nozzle. The prepared polymer/solid electrolyte nanofibers were recovered from the collector and heat-treated at 700° C. for 3 hours to prepare a one-dimensional LLZO solid electrolyte. The SEM shape analysis result of the prepared one-dimensional solid electrolyte is shown in FIG. 3 . In this case, it can be seen that the one-dimensional solid electrolyte is a Li ₇ La ₃ Zr ₂ O ₁₂ oxide-based solid electrolyte, and exhibits an aspect ratio (length/diameter) of about 20 to 80.

As a binder, polyethylene oxide and LiClO ₄ were dissolved in acetonitrile (ACN, acetonitrile) to prepare a binder solution. An electrode slurry was prepared by quantifying natural graphite/one-dimensional solid electrolyte/binder according to a weight ratio of 80:15:5, and mixing the mixture at 1500 rpm to 2000 rpm for 10 minutes to 30 minutes on a stirrer. If necessary, the stirring process may be repeated 2 to 3 times. The electrode slurry was coated on copper foil by controlling the thickness by a doctor blade method and dried in a vacuum oven at 90°C to 110°C for 12 hours to 24 hours. The loading level of the prepared composite negative electrode was adjusted to 5 mg/cm ² to 12 mg/cm ² depending on the coating thickness.

In order to analyze the battery characteristics of the composite cathode, an all-solid-state half cell composed of a composite cathode/solid electrolyte/lithium metal was prepared. Li ₇ P ₃ S ₁₁ glass-ceramic (LPS) was used as the solid electrolyte film between the composite anode and the lithium metal electrode. First, the solid electrolyte layer was formed by cold sintering at a pressure of 200 MPa to 400 MPa. After forming a composite negative electrode and a lithium metal electrode on both sides of the solid electrolyte layer, a pressure of 100 MPa to 200 MPa was applied to form a close interface with the solid electrolyte layer, the composite negative electrode, and the lithium metal electrode to prepare an all-solid-state secondary battery.

Comparative Example 1

Except for putting a 0-dimensional solid electrolyte in the composite cathode instead of a one-dimensional solid electrolyte, and quantifying the natural graphite / 1 dimensional solid electrolyte / binder according to a weight ratio of 55:40:5, preparing the example described above An all-solid-state secondary battery was manufactured by the same method as the method. Specifically, to prepare an LLZO solid electrolyte with a 0-dimensional structure, lithium carbonate (LiCO ₃ ) as a Li (lithium) source, lanthanum oxide (La ₂ O ₃ ) as a la (lanthanum) source, and zirconium oxide (ZrO ₂ ) as an M source ) was mixed in a powder state. The molar ratio of the Li, La, and Zr sources was maintained at 7:3:2. For uniform mixing, Isopropyl alcohol (IPA) was added and the ball-milling method, which is a mechanical grinding and mixing method, was performed and mixed for 6 to 12 hours. The mixed powders obtained by performing the ball-milling method were then dried in a drying oven maintained at 100° C. to obtain a dried powder state. The mixed powder was subjected to a primary heat treatment process for 4 hours in a reactor maintained at 1000 °C. A secondary heat treatment process was performed at 1200 °C for 12 hours. A composite cathode was prepared by quantifying natural graphite/1D solid electrolyte/binder in a weight ratio of 55:40:5, and then an all-solid-state secondary battery was prepared.

Compared to the shape of a pure graphite electrode without a solid electrolyte, the composite electrode layer contains a solid electrolyte to form an ion transport path. It shows that the 0-dimensional solid electrolyte does not form a reliable ion transport path at 20 wt%, whereas a relatively sufficient ion transport path is formed in the composite electrode layer containing 40 wt% of the 0-dimensional solid electrolyte.

Comparative Example 2

A composite cathode was manufactured in the same manner as in the preparation of Comparative Example described above, except that natural graphite/1D solid electrolyte/binder was quantified according to a weight ratio of 55:20:5.

Experimental Example 1

The results of EDS-mapping analysis of the cross-sectional structure of the composite anode prepared according to the example are shown in FIG. 4 . The result of EDS-mapping analysis of the cross-sectional structure of a pure graphite electrode without a solid electrolyte is shown in FIG. 5a. The results of EDS-mapping analysis of the cross-sectional structure of the composite negative electrode prepared according to Comparative Example 1 are shown in FIG. 5B. The results of EDS-mapping analysis of the cross-sectional structure of the composite anode prepared according to Comparative Example 2 are shown in FIG. 5c .

Referring to FIG. 4 , the presence of a one-dimensional solid electrolyte could be confirmed by elemental analysis of La or Zr. 4, 5A, 5B, and 5C, compared to the pure graphite electrode without a solid electrolyte and Comparative Example 2, the composite electrode according to the embodiment of the present invention has a relatively sufficient ion transport path. can confirm.

Experimental Example 2

In order to analyze the charge/discharge characteristics, the cut-off voltage was set to 0.001 V to 2 V based on the CC (constant current) mode, and charging and discharging were performed 30 times at a 0.1C rate. In addition, in order to confirm the high-temperature driving characteristics, the charge/discharge analysis was performed at 60 °C. The results of charging and discharging of the all-solid-state secondary battery prepared according to the example are shown in FIG. 6 . The results of charging and discharging of the all-solid-state secondary battery prepared according to Comparative Example 1 are shown in FIG. 7 .

6 and 7 , the initial capacity of Example was 96.38 mAh/g, and the initial capacity of Comparative Example 1 was 303.8 mAh/g, showing no significant difference. The charging/discharging results of the examples were measured to be 296.1 mAh/g, 294.9 mAh/g, 284.4 mAh/g, 269.5 mAh/g, and 257.1 mAh/g, respectively, in 2, 3, 10, 20, and 29 cycles. The charging and discharging results of the comparative example were measured to be 300.68 mAh/g, 297.4 mAh/g, 276.9 mAh/g, 243.3 mAh/g, and 205.1 mAh/g in 2, 3, 10, 20, and 30 cycles, respectively. Accordingly, it can be seen that the capacity of the all-solid-state secondary battery of Comparative Example rapidly decreases as the cycle progresses, whereas the capacity of the all-solid-state secondary battery according to the present invention is relatively well maintained even when the cycle progresses.

Experimental Example 3

8 shows the lifespan characteristics of the all-solid-state secondary battery prepared according to the example. The results of the lifespan characteristics of the all-solid-state secondary battery prepared according to Comparative Example 1 are shown in FIG. 9 . 8 and 9 show charge capacity (●: discharge), discharge capacity (○: charge) and Coulombic efficiency (♦: Coulombic efficiency) in a cut-off voltage range of 0.001 V to 2 V for 30 times at 60° C. in CC mode. ) shows the results. Referring to FIGS. 8 and 9 , the Example showed a capacity of 86.8% compared to the initial capacity at 30 cycles, whereas the Comparative Example showed a capacity of 67.5% compared to the initial capacity at 30 cycles. The lifespan characteristics of the all-solid-state secondary battery including a lesser content (15 wt%) of the one-dimensional solid electrolyte according to the present invention, the all-solid secondary battery including a relatively higher content (40 wt%) of the zero-dimensional solid electrolyte It can be confirmed that it is superior to the battery. That is, it can be confirmed that the lifespan characteristics of the all-solid-state secondary battery according to the present invention are improved.

As mentioned above, although embodiments of the present invention have been described with reference to the accompanying drawings, those of ordinary skill in the art to which the present invention pertains can practice the present invention in other specific forms without changing its technical spirit or essential features. You will understand that there is Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

Claims (1)

anode;
cathode; and
A solid electrolyte layer disposed between the positive electrode and the negative electrode,
At least one of the positive electrode and the negative electrode includes a one-dimensional solid electrolyte material, an electrode active material, and a binder,
The aspect ratio of the one-dimensional solid electrolyte material is 20 to 1000,
The content of the one-dimensional solid electrolyte material is 5 wt% to 20 wt% based on the weight of at least one of the positive electrode and the negative electrode.

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