KR102570543B1 - Anode for all-solid-state battery including graphene-metal nanoparticle composite and all-solid-state battery including the same - Google Patents

Abstract

The present invention relates to a negative electrode for an all-solid-state battery comprising a negative electrode active material composed of a graphene-metal particle composite and an all-solid-state battery including the same, wherein the negative electrode for an all-solid-state battery according to the present invention includes a three-dimensional porous graphene structure and metal particles By including the graphene-metal particle composite prepared by photosintering a mixture of as an anode active material, irregular growth of metal lithium dendrite formed between the anode active material layer and the anode current collector layer during charging and solid electrolyte penetration It is possible to implement an all-solid-state battery with both performance and stability by solving the problem of deterioration of battery characteristics and significantly improving charge/discharge speed and efficiency at the same time.

Description

Anode for all-solid-state battery including a graphene-metal particle composite and all-solid-state battery including the same

The present invention relates to an anode for an all-solid-state battery and an all-solid-state battery including the same, and more particularly, to a cathode including a graphene-based composite material (hybrid graphene) as an anode active material and an all-solid-state battery including the same.

There are various secondary batteries that can be charged and discharged, such as lead-acid batteries and nickel-metal hybrid batteries, but among them, lithium-ion batteries (LIBs) have high energy density, high power density, and can withstand long periods of charge and discharge. It is not only used as a battery that supplies power to portable mobile devices such as smart phones and net books due to voltage reasons, but also widely used as energy supply members to supply energy to hybrid vehicles, etc. It is being utilized.

However, currently commercialized lithium ion batteries contain liquid electrolytes, so the battery is deformed during continuous use, and is easily ignited when there is an ignition source. It has a problem of deteriorating stability.

In order to solve the above-mentioned problems, a solid state solid electrolyte that can move lithium ions is introduced, and the risk of explosion and ignition is low, so that it can be used stably (all-solid-state battery (ASSB)). ) has recently received a lot of attention.

In order to increase the energy density of an all-solid-state battery, a technology is known to use lithium metal (Li-metal) as an anode active material layer. As the solid battery is repeatedly charged and discharged, lithium deposited on the negative electrode side grows lithium dendrites through gaps in the solid electrolyte, and the lithium dendrites thus grown cause a short circuit or decrease in capacity of the battery.

Therefore, it is required to develop a new anode material for all-solid-state batteries that can advance the commercialization of all-solid-state batteries by improving the characteristics of all-solid-state batteries compared to the prior art by solving or mitigating the above problems.

Korean Patent Publication No. 10-2020-0129379 (published date: 2020.11.18) Korean Patent Publication No. 10-2019-0137691 (published date: 2019.12.11)

The technical problem to be solved by the present invention is a new method that can solve the problem of deterioration in battery characteristics due to irregular growth of lithium dendrites and penetration of solid electrolyte in a conventional all-solid-state battery including a negative electrode active material layer made of lithium metal. It is to provide a negative electrode for an all-solid-state battery and an all-solid-state battery including the same.

In order to achieve the above technical problem, the present invention proposes a negative electrode for an all-solid-state battery including a negative electrode active material made of a graphene-metal particle composite.

In addition, the graphene-metal particle composite is prepared by irradiating light to a mixture of a three-dimensional porous graphene structure and metal particles to cause a photochemical and / or photothermal reaction as in a light sintering process. An anode for an all-solid-state battery, characterized in that it is a composite of a two-dimensional porous graphene structure and metal particles, is proposed.

In addition, the graphene-metal particle composite proposes a negative electrode for an all-solid-state battery, characterized in that it has a network structure formed by interconnecting the three-dimensional porous graphene structure and the metal particles.

In addition, the metal particles are made of a metal selected from the group consisting of silver (Ag), gold (Au), platinum (Pt), palladium (Pd), aluminum (Al) and zinc (Zn). A cathode for a solid battery is proposed.

And, the present invention, in another aspect of the invention, as an example of an all-solid-state battery comprising a negative electrode for an all-solid-state battery according to the present invention, a positive electrode including a positive electrode current collector and a positive electrode active material layer; a solid electrolyte layer; and an anode including an anode active material layer including a cathode current collector and an anode active material made of the graphene-metal particle composite.

In addition, the cathode active material layer may include a lithium-nickel-cobalt-manganese composite oxide (NCM), a lithium-nickel-cobalt-aluminum composite oxide (NCA), a lithium-cobalt composite oxide (LCO), and a lithium-nickel composite. An all-solid-state battery comprising at least one positive electrode active material selected from the group consisting of complex oxide (LNO) is proposed.

In addition, the solid electrolyte layer includes Li ₂ SP ₂ S ₅ -LiI, Li ₂ SP ₂ S ₅ -LiCl, Li ₂ SP ₂ S ₅ -LiBr, Li ₂ SP ₂ S ₅ -Li ₂ O, Li ₂ SP ₂ S ₅ -Li ₂ O-LiI, Li ₂ S-SiS ₂ , Li ₂ S-SiS ₂ -LiI, Li ₂ S-SiS ₂ -LiBr, Li ₂ S-SiS ₂ -LiCl, Li ₂ S-SiS ₂ - selected from the group consisting of B ₂ S ₃ -LiI, Li ₂ S-SiS ₂ -P ₂ S ₅ -LiI, Li ₂ SB ₂ S ₃ , Li ₂ S-GeS2 and Li ₂ S-SiS ₂ -Li ₃ PO ₄ We propose an all-solid-state battery comprising at least one solid electrolyte.

The negative electrode for an all-solid-state battery according to the present invention includes a three-dimensional porous graphene structure and a metal particle composite prepared by a photochemical and/or photothermal reaction method as an anode active material, and is formed between the anode active material layer and the anode current collector layer during charging. It is possible to realize an all-solid-state battery with both performance and stability by significantly improving the charging and discharging speed and efficiency while solving the problem of deterioration of battery characteristics due to the irregular growth of metal lithium dendrites and penetration of solid electrolyte.

1A is a scanning electron microscope (SEM) photograph showing silver particles (Ag) before performing a photothermal irradiation process.
Figure 1b is a scanning electron microscope (SEM) picture showing silver particles (Ag) after performing a photothermal irradiation process.
Figure 1c is a scanning electron microscope (SEM) picture showing a porous graphene structure (3-dimensional nanoporous graphene) prepared by photochemical and photothermal reactions without metal particles.
1d is a scanning electron microscope (SEM) photograph showing a graphene-metal particle composite for an anode active material for an all-solid-state battery prepared by photochemical and photothermal reactions in the present example.
2 is an electrochemical measurement substance (PAP) for each of a graphene-metal particle composite (Graphene-Ag electrode), a graphene electrode, and a metal electrode (Gold electrode) for an all-solid-state battery negative electrode active material according to the present invention. It is a graph showing the current measurement result according to the concentration of
Figure 3 is the same concentration (1.0 × 10 ^-3 mM) for each of graphene-metal particle composite (Hybrid Graphene), graphene (Graphene) and metal (Metal (Au)) for all-solid-state battery negative active material according to the present invention It is a graph showing the current value at the PAP of
Figure 4 is a real-time graph of measuring various concentrations of electrochemical measurement substances (PAP) using the hybrid graphene electrode for an all-solid-state battery negative electrode according to the present invention.
5 is an example of an all-solid-state battery including a negative electrode for an all-solid-state battery according to the present invention, a positive electrode including a positive electrode active material (NMC), a sulfide-based solid electrolyte layer, and a negative electrode current collector (SUS) and the graphene- It is a schematic cross-sectional view of an all-solid-state battery having a negative electrode including a negative electrode active material layer including a negative electrode active material made of a metal particle composite.

In describing the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description will be omitted.

Embodiments according to the concept of the present invention can be applied with various changes and can have various forms, so specific embodiments are illustrated in the drawings and described in detail in this specification or application. However, this is not intended to limit the embodiments according to the concept of the present invention to a specific disclosed form, and should be understood to include all changes, equivalents, or substitutes included in the spirit and technical scope of the present invention.

Terms used in this specification are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, terms such as "comprise" or "having" are intended to designate that the described feature, number, step, operation, component, part, or combination thereof exists, but one or more other features or numbers However, it should be understood that it does not preclude the presence or addition of steps, operations, components, parts, or combinations thereof.

Hereinafter, the present invention will be described in detail.

The negative electrode for an all-solid-state battery according to the present invention includes a graphene-metal particle composite, which is a composite material of graphene and metal particles, as an anode active material.

The graphene-metal particle composite is an anode material constituting the anode active material layer, and serves to occlude lithium (Li) during charging of an all-solid-state battery. It serves as a protective layer for the lithium metal layer by covering the metal lithium layer precipitated at the interface, and at the same time, it suppresses excessive growth of lithium dendrites to block penetration into the solid electrolyte layer and induces uniform growth of lithium dendrites. , it is possible to prevent a short circuit and decrease in capacity of an all-solid-state battery, and consequently improve the performance of the all-solid-state battery.

At this time, graphene constituting the graphene-metal particle composite plays a role in increasing the charge/discharge rate and efficiency of the all-solid-state battery because electrons are supplied uniformly and smoothly due to high electron mobility, and also has a high Young's modulus. (Young's modulus), it is possible to efficiently support the expansion of the anode active material due to the combination of metal particles such as silver (Ag) particles and lithium (Li).

Meanwhile, the graphene constituting the graphene-metal particle composite is preferably derived from a three-dimensional porous graphene structure rather than pure graphene without defects.

Pure graphene without defects itself has excellent physical properties such as excellent electrical conductivity and high specific surface area, but the advantage of the increased specific surface area is greatly reduced due to irreversible self-aggregation.

On the other hand, a three-dimensional porous graphene structure in which pores are three-dimensionally and organically connected between single-layer and/or multi-layer graphene sheets has a relatively larger specific surface area due to reduced self-aggregation, and electrons and ions move more rapidly. Because it diffuses, it shows relatively superior properties in electrochemical applications such as energy conversion and storage devices. In addition, the three-dimensional porous graphene structure has the advantage of being able to control pore characteristics (position and size of pores, etc.) through control of process parameters during the manufacturing process.

Furthermore, the 3D porous graphene structure changes the electronic structure of graphene through chemical doping that adsorbs heterogeneous materials such as metal particles, such as the graphene-metal particle composite according to the present invention, so that the electrical properties can be controlled. may be

On the other hand, the manufacturing method of the three-dimensional porous graphene structure is not particularly limited, but a method using a hard template or a soft template is mainly used. Methods using the hard casting method include a method using a spherical polymer, a method using metal oxide particles, and a method using a porous substrate such as nickel foam. In the soft casting method, surfactant molecules self-assemble (self-assembly). ), it is possible to synthesize a material with a controlled pore size using the micelle template made, and it has the advantage of being relatively easy to remove the template compared to the hard template method.

In addition, after forming a polymer coating layer, a stabilization reaction is induced so that carbon atoms in the polymer have a hexagonal ring arrangement, and carbonization is performed at a high temperature to prepare a three-dimensional porous graphene structure. In this case, the polymer may include poly(methyl methacrylate) (PMMA), polystyrene (PS), polyimide (PI), etc. as specific examples, but is not necessarily limited thereto, and high temperature There are no particular restrictions on the structure, molecular weight, glass transition temperature, etc. of a polymer that can serve as a carbon source for carbonization to form graphene.

The metal particles constituting the graphene-metal particle composite by being composited with the graphene are silver (Ag), copper (Cu), gold (Au), platinum (Pt), palladium (Pd), aluminum (Al), zinc It may be a metal particle made of a pure metal such as (Zn) or an alloy thereof, and further, the metal particle includes a core particle made of one of the metals and a coating layer made of a metal different from the metal constituting the core particle It may be metal particles (eg, silver-coated copper particles, copper-coated silver particles, etc.), but is not necessarily limited to the above-mentioned metal particles.

Taking a silver (Ag) particle among the metal particles as an example, the silver (Ag) particle dissolves in lithium (Li) and lowers the energy for crystallizing lithium, so that lithium generates pores and grows more uniformly without growing unevenly As a result, it contributes to improving the performance of all-solid-state batteries.

As a method for preparing the graphene-metal particle composite by combining graphene and metal particles, the three-dimensional porous graphene structure and metal particles are uniformly mixed through a stirring process such as ball-milling and A composite method is also possible, but more preferably, light is irradiated to a mixture in which the three-dimensional porous graphene structure and the metal particles are uniformly mixed to sinter the mixture, so that the metal particles are interconnected and the graphene sheets are interconnected. A graphene-metal particle composite having a three-dimensional network structure in which connections and interconnections between metal particles and graphene sheets are organically formed may be prepared.

The all-solid-state battery including the negative electrode active material made of the graphene-metal particle composite includes a positive electrode including a positive electrode current collector and a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material made of the negative electrode current collector and the graphene-metal particle composite It may be made including a negative electrode comprising a negative electrode active material layer containing.

At this time, the positive electrode active material layer includes a lithium-nickel-cobalt-manganese composite oxide (NCM), a lithium-nickel-cobalt-aluminum composite oxide (NCA), a lithium-cobalt composite oxide (LCO), and a lithium-nickel composite. It may include one or more types of cathode active material selected from the group consisting of complex oxide (LNO), but the constituent materials are not necessarily limited to the cathode active material.

In addition, the type of solid electrolyte constituting the solid electrolyte layer is not particularly limited, but may include a sulfide-based solid electrolyte, for example, Li ₂ SP ₂ S ₅ -LiI, Li ₂ SP ₂ S ₅ -LiCl , Li ₂ SP ₂ S ₅ -LiBr, Li ₂ SP ₂ S ₅ -Li ₂ O, Li ₂ SP ₂ S ₅ -Li ₂ O-LiI, Li ₂ S-SiS ₂ , Li ₂ S-SiS ₂ -LiI, Li ₂ S-SiS ₂ -LiBr, Li ₂ S-SiS ₂ -LiCl, Li ₂ S-SiS ₂ -B ₂ S ₃ -LiI, Li ₂ S-SiS ₂ -P ₂ S ₅ -LiI, Li ₂ SB ₂ It may be one or more selected from the group consisting of S ₃ , Li ₂ S-GeS2 and Li ₂ S-SiS ₂ -Li ₃ PO ₄ .

Hereinafter, the present invention will be described in more detail by way of examples.

Embodiments according to the present specification may be modified in many different forms, and the scope of the present specification is not construed as being limited to the embodiments detailed below. The embodiments herein are provided to more completely explain the present specification to those skilled in the art.

1A is a scanning electron microscope (SEM) photograph showing silver particles (Ag) before performing a photothermal irradiation process for preparing a graphene-metal particle composite, which is an anode active material included in a cathode for a solid battery according to the present invention.

Referring to FIG. 1A , silver (Ag) particles before photothermal irradiation have a spherical particle diameter of about 5 μm.

Figure 1b is a scanning electron microscope (SEM) picture showing silver particles (Ag) after performing a photothermal irradiation process.

Referring to FIG. 1B , it is confirmed that the surfaces of silver (Ag) particles are bonded and solidified with adjacent particles in a molten state using photothermal irradiation, and it can be seen that some particles are not connected to form empty spaces.

FIG. 1C is a scanning electron microscope showing a porous graphene structure (3-dimensional nanoporous graphene) before performing a photothermal irradiation process for preparing a graphene-metal particle composite, which is an anode active material included in a cathode for a solid battery according to the present invention. (SEM) This is a picture.

Referring to FIG. 1C , it can be confirmed that the multilayer graphene has a three-dimensional overlapped or bent structure.

1D is a scanning electron microscope showing a graphene-metal particle composite for an anode active material for an all-solid-state battery according to the present invention prepared by performing a photothermal irradiation process on a mixture of a three-dimensional porous graphene structure and silver particles (Ag) in the present example. (SEM) This is a picture.

Referring to FIG. 1D , a microstructure of a graphene-metal particle composite having a network structure formed by interconnecting silver (Ag) particles and a three-dimensional porous graphene structure through a photothermal irradiation process can be confirmed.

2 is an electrochemical measurement material (p- This is a graph showing the current measurement results according to the concentration of Aminophenol (PAP).

For each electrode, the magnitude of the current signal gradually increases according to the PAP concentration.

In addition, for the same concentration of PAP, the signal of the graphene electrode, which has advantages in surface area and electron inflow and emission, becomes larger than that of the metal electrode, and the signal of the graphene-metal particle composite electrode, which has a smaller resistance than the graphene electrode, is higher It can be seen that the measurement is large.

Figure 3 is the same concentration (1.0 × 10 ^-3 mM) for each of graphene-metal particle composite (Hybrid Graphene), graphene (Graphene) and metal (Metal (Au)) for all-solid-state battery negative active material according to the present invention It is a graph showing the current value at the PAP of

Referring to FIG. 3 , it can be seen that the current signal of the graphene-metal particle composite electrode generates a larger signal than that of the comparison electrodes, so that the signal to noise ratio (SNR) is greater than that of the comparison electrode.

Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art can implement 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 (7)

Including a negative electrode active material made of a graphene-metal particle composite,
The graphene-metal particle composite,
The interconnection between the metal particles and the graphene sheet is organically interconnected in a network structure by photochemical or photothermal reaction,
Characterized in that it comprises a three-dimensional graphene composite layer in which several layers of graphene are stacked and bent in an arbitrary direction
Cathode for all-solid-state batteries. delete According to claim 1,
The metal particles are silver (Ag), gold (Au), platinum (Pt), palladium (Pd), aluminum (Al), zinc (Zn), silver alloy (Ag alloy), surface coated with silver (Ag) Characterized in that it is made of a metal selected from the group consisting of copper (Cu) and silver (Ag) whose surface is coated with copper (Cu).
Cathode for all-solid-state batteries. delete a positive electrode including a positive electrode current collector and a positive electrode active material layer;
a solid electrolyte layer; and
a negative electrode according to claim 1 or 3;
An all-solid-state battery comprising a. According to claim 5,
The positive electrode active material layer,
from the group consisting of lithium-nickel-cobalt-manganese composite oxide (NCM), lithium-nickel-cobalt-aluminum composite oxide (NCA), lithium-cobalt composite oxide (LCO) and lithium-nickel composite oxide (LNO) An all-solid-state battery comprising at least one selected positive electrode active material. According to claim 5,
The solid electrolyte layer,
Li ₂ SP ₂ S ₅ -LiI, Li ₂ SP ₂ S ₅ -LiCl, Li ₂ SP ₂ S ₅ -LiBr, Li ₂ SP ₂ S ₅ -Li ₂ O, Li ₂ SP ₂ S ₅ -Li ₂ O-LiI , Li ₂ S-SiS ₂ , Li ₂ S-SiS ₂ -LiI, Li ₂ S-SiS ₂ -LiBr, Li ₂ S-SiS ₂ -LiCl, Li ₂ S-SiS ₂ -B ₂ S ₃ -LiI, Li ₂ S-SiS ₂ -P ₂ S ₅ -LiI, Li ₂ SB ₂ S ₃ , Li ₂ S-GeS2 and Li ₂ S-SiS ₂ -Li ₃ PO ₄ including at least one solid electrolyte selected from the group consisting of An all-solid-state battery characterized in that.