Anode for lithium-ion batteries containing hybrid graphene

Abstract

The present invention relates to a negative electrode for a lithium ion battery, comprising a negative electrode active material comprising a graphene-fine particle composite, the graphene-fine particle composite having a three-dimensional structure in which a plurality of layers of graphene are stacked and bent in any direction, the fine particles are bonded to a surface or inside of the graphene, some fine metal particles are bonded and solidified with each other, and some of the spaces between the fine particles are filled with the graphene composite layer and interconnected with each other.

Description

[Technical Field]

[0001] The present invention relates to a negative electrode for a lithium-ion battery, and more particularly to a negative electrode containing a graphene-based composite material (hybrid graphene) as the negative electrode active material, and to a lithium-ion battery related thereto. [Background technology]

[0002] There are various types of rechargeable batteries, such as lead-acid batteries and nickel-metal hybrid batteries, but lithium-ion batteries (LIBs) are particularly popular due to their high energy density, high power density, and operating voltage that can withstand long charge-discharge cycles. They are used not only as power sources for portable mobile devices such as smartphones and netbooks, but also as energy supply components for hybrid vehicles and other applications.

[0003] In lithium-ion batteries, the positive electrode active material is varied to improve performance. However, even if high energy is generated by the positive electrode material, if the negative electrode material, which stores this energy, does not support it in a balanced manner, the efficiency will inevitably be poor. In particular, if the negative electrode material is manufactured to readily accept lithium ions during charging, the charging time can be reduced. Graphite has long been widely used as the negative electrode active material. Graphite has a layered structure in which layers of carbon atoms bonded in a regular pattern are stacked on top of each other. During the charging process, when lithium ions move from the positive electrode to the negative electrode, the lithium ions that reach the negative electrode are stored between the graphite layers.

[0004] Currently, research is underway to develop new materials that can replace existing graphite anode materials in order to improve the performance of lithium-ion batteries. Graphite has low electrical conductivity, resulting in long charge and discharge times, and its capacity to bind lithium ions is insufficient, leading to low charging capacity.

[0005] Therefore, there is a need to develop a new anode material that can resolve or mitigate the aforementioned problems, improve the properties of the anode material compared to conventional technology, increase the charging capacity and battery life of lithium-ion batteries, and shorten the charging time. [Overview of the project] [Problems that the invention aims to solve]

[0006] The technical problem that this invention aims to solve is to address the problems in conventional lithium-ion batteries that contain graphite as the negative electrode active material layer, where the charge-discharge time is long because graphite has low electrical conductivity, and the charging capacity is not high because the capacity for lithium ions to bind is insufficient. Therefore, the invention aims to provide a negative electrode for a lithium-ion battery containing hybrid graphene, which is a graphene composite multilayer structure in which metal or semiconductor particles are melt-bonded to graphene to form a three-dimensional network, and a lithium-ion battery containing the same. [Means for solving the problem]

[0007] In this invention, in order to overcome these problems, we propose a hybrid graphene structure in which metal or semiconductor particles are interconnected with a graphene multilayer in a network structure, and the metal or semiconductor particles can be maintained in a stable state even after repeated charging and discharging. Existing processes for mixing graphene with metal or semiconductor particles are simply processes of mixing with already produced graphene, resulting in insufficient organic bonding force between the metal or semiconductor particles and graphene.

[0008] In this invention, since metal or semiconductor fine particles are mixed during the manufacturing process of graphene, the surface of the metal or semiconductor fine particles is melted and solidified with the graphene, and the fine particles and graphene are joined together to form a three-dimensional nanostructure.

[0009] Furthermore, the formed graphene composite is composed of multilayer graphene, and therefore has a structural characteristic in which metal or semiconductor fine particles are bonded to the surface or interior of the multilayer graphene structure, and the spaces between the silicon fine particles are filled with graphene composite layers that are interconnected.

[0010] Thus, a hypothetical negative electrode active material structure consisting of a graphene composite having a structure in which metal or semiconductor fine particles and multilayer graphene are mixed has the following effects.

[0011] Firstly, since the surface of the metal or semiconductor microparticles is completely coated with graphene, the volume expansion that occurs when the metal or semiconductor microparticles combine with lithium ions is effectively suppressed. Through this, the problem of the metal or semiconductor particles breaking down and separating from the electrodes due to excessive volume expansion and contraction can be solved.

[0012] Secondly, the multilayer graphene layers act as a scaffold, fixing the position of the metal or semiconductor. Theoretically, graphene has 200 times the tensile strength of steel, so it does not easily break even when bent. Therefore, when graphene is bonded with metal or semiconductor microparticles to form a multilayer structure, the position of the metal or semiconductor microparticles is fixed, and it acts as a scaffold, maintaining a stable structure even with morphological changes of the metal or semiconductor due to charging and discharging.

[0013] Thirdly, graphene possesses high electron mobility and current density, which facilitates electron transfer with lithium ions. Through this, electron transfer with metal or semiconductor fine particles proceeds smoothly, increasing the charge and discharge rate and improving the charging and discharging efficiency of graphene-metal or semiconductor composite structures.

[0014] To achieve the aforementioned technical objectives, the present invention provides a negative electrode for a lithium-ion battery comprising a negative electrode active material made of a hybrid graphene composite, wherein the hybrid graphene composite has a three-dimensional structure in which multiple layers of graphene are stacked and bent in any direction, the metal particles are bound to the surface or interior of the graphene, some fine metal particles are interbonded and solidified, and some of the spaces between the metal particles are filled and interconnected by the graphene composite layer.

[0015] Furthermore, the present invention provides a negative electrode for a lithium-ion battery, characterized in that the surface of the fine metal particles is coated with graphene.

[0016] Furthermore, the present invention provides a negative electrode for a lithium-ion battery, characterized in that the graphene-metal composite is produced by a photochemical, photothermal irradiation, or heat treatment process.

[0017] Furthermore, the metal or semiconductor particles of the present invention include silver (Ag), silicon (Si), and silicon carbide (Si2C, SiC, or SiC2). X ), silicon oxide (SiO or SiO2 containing SiO2) X ), silicon composite oxide (Si-Mg x SiO x The present invention provides a negative electrode for lithium-ion batteries, characterized by being made of a metal or semiconductor selected from the group consisting of magnesium metasilicate (enstatite, MgSiO3), forsterite (forsterite, Mg2SiO4), gold (Au), platinum (Pt), palladium (Pd), aluminum (Al), zinc (Zn), silver alloy (Ag alloy), copper (Cu) coated with silver (Ag), and silver (Ag) coated with copper (Cu).

[0018] Furthermore, the present invention provides a negative electrode for a lithium-ion battery characterized by having a network structure formed by the interconnection of the three-dimensional porous graphene structure and the metal particles.

[0019] The present invention also provides a positive electrode including a positive electrode current collector and a positive electrode active material layer, a solid electrolyte layer, and an all-solid-state battery including the negative electrode.

[0020] The positive electrode active material layer according to the present invention includes one or more positive electrode active materials selected 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), and provides an all-solid-state battery.

[0021] The solid electrolyte layer according to the present invention includes one or more solid electrolytes selected from the group consisting of Li₂S-P₂S₅-LiI, Li₂S-P₂S₅-LiCl, Li₂S-P₂S₅-LiBr, Li₂S-P₂S₅-Li₂O, Li₂S-P₂S₅-Li₂O-LiI, Li₂S-SiS₂, Li₂S-SiS₂-LiI, Li₂S-SiS₂-LiBr, Li₂S-SiS₂-LiCl, Li₂S-SiS₂-B₂S₃-LiI, Li₂S-SiS₂-P₂S₅-LiI, Li₂S-B₂S₃, Li₂S-GeS₂, and Li₂S-SiS₂-Li₃PO₄, and provides an all-solid-state battery.

Effects of the Invention

[0022] The negative electrode for a lithium-ion battery according to the present invention includes a three-dimensional porous hybrid graphene composite produced by a photochemical, photothermal irradiation or heat treatment process method as a negative electrode active material, thereby forming a stable graphene composite structure, significantly improving the charge and discharge rate and efficiency with high electrical conductivity, and maximizing the capacity for lithium ions to bind, realizing a lithium-ion battery with excellent performance and stability.

Brief Description of Drawings

[0023] [Figure 1a]Scanning electron microscope (SEM) photograph and conceptual diagram showing silver particles (Ag) before performing the photothermal irradiation process. [Figure 1b] Scanning electron microscope (SEM) photograph showing silver particles (Ag) after performing the photothermal irradiation process. [Figure 1c] Scanning electron microscope (SEM) photograph showing a porous graphene structure (three-dimensional nanoporous graphene) manufactured by photochemistry, photothermal irradiation, or heat treatment without metal particles. [Figure 1d] Scanning electron microscope (SEM) photograph showing a hybrid graphene composite for a negative electrode active material of an all-solid-state battery manufactured by photochemistry, photothermal irradiation, or heat treatment in an embodiment of the present application. [Figure 1e] Conceptual diagram showing a structure in which graphene manufactured by the photochemical, photothermal irradiation, or heat treatment reaction of (d) in an embodiment of the present application is located and fixed in a space (b) where silver (Ag) fine particles are vacant. [Figure 2] Graph showing the current measurement results according to the concentration of an electrochemically measured substance (PAP) for each of a hybrid graphene composite electrode (Hybrid Graphene complex electrode, Graphene-Ag electrode), a graphene electrode (Graphene electrode), and a metal electrode (Gold electrode) for a negative electrode active material of an all-solid-state battery according to the present invention. [Figure 3] Graph showing a comparison of the current values in PAP at the same concentration (10-3 mM) for each of a hybrid graphene composite (Hybrid Graphene), graphene (Graphene), and metal (Metal(Au)) for a negative electrode active material of an all-solid-state battery according to the present invention. [Figure 4] Real-time graph showing the measurement of various concentrations of an electrochemically measured substance (PAP) using a hybrid graphene electrode for a negative electrode of an all-solid-state battery according to the present invention. [Figure 5]This is a schematic cross-sectional view of an example of an all-solid-state battery including the negative electrode for all-solid-state batteries according to the present invention, comprising a positive electrode containing a positive electrode active material (NMC), a sulfide-based solid electrolyte layer, a negative electrode current collector (SUS), and a negative electrode containing a negative electrode active material layer comprising the negative electrode active material made of the hybrid graphene composite. [Figure 6] These are photographs showing cross-sections of the charging (a) and discharging (b) states of the negative electrode for an all-solid-state battery containing the hybrid graphene composite of the present invention. [Figure 7] This is a photograph of the hybrid graphene anode fabricated according to the present invention (left) and a coin cell battery fabricated using it (right). [Modes for carrying out the invention]

[0024] In describing the present invention, if it is determined that a specific description of a related known function or configuration may obscure the gist of the invention, such detailed description will be omitted.

[0025] Embodiments based on the concept of the present invention can be modified in various ways and may take many forms. Therefore, specific embodiments are illustrated in the drawings and described in detail in this specification or application. However, this is not intended to limit embodiments based on the concept of the present invention to any particular disclosed form, but rather should be understood to include all modifications, equivalents, or substitutes that fall within the spirit and technical scope of the present invention.

[0026] The terms used herein are used solely to describe specific embodiments and are not intended to limit the invention. A singular expression includes plural expressions unless the context clearly intends otherwise. In this specification, terms such as “includes” or “having” are intended to specify the existence of a described feature, figure, step, action, component, part, or combination thereof, and should not be understood to preemptively exclude the existence or possibility of adding one or more other features, figures, steps, actions, components, parts, or combinations thereof.

[0027] The present invention will be described in detail below.

[0028] This invention relates to an all-solid-state battery anode for lithium-ion batteries, and is characterized by the fact that the anode active material is a hybrid graphene composite, which is a composite material of graphene and metal particles.

[0029] The aforementioned hybrid graphene composite is a negative electrode material constituting the negative electrode active material layer in a lithium-ion battery. During charging, it absorbs lithium (Li), and after the charging capacity is exceeded, it coats the metallic lithium layer deposited at the interface between the negative electrode current collector and the negative electrode active material layer, acting as a protective layer for the lithium metallic layer. At the same time, it suppresses the excessive growth of lithium dendrites, blocking their penetration into the solid electrolyte layer and inducing uniform growth of lithium dendrites. This prevents short circuits and capacity degradation in the all-solid-state battery, ultimately improving the performance of the all-solid-state battery.

[0030] In this case, the graphene constituting the hybrid graphene composite has high electron mobility, which allows for uniform and smooth electron supply, thereby increasing the charge-discharge rate and efficiency of the all-solid-state battery. Furthermore, it has a high Young's modulus, which can efficiently support the expansion phenomenon of the negative electrode active material caused by the bonding of metal particles such as silver (Ag) particles with lithium (Li).

[0031] On the other hand, it is preferable that the graphene constituting the hybrid graphene composite is derived from a three-dimensional porous graphene structure rather than pure graphene without defects.

[0032] The aforementioned hybrid graphene composite has a three-dimensional structure in which multiple layers of graphene are stacked and bent in any direction, and the metal particles are bonded to the surface or interior of the graphene by photochemical, photothermal irradiation or heat treatment, and some fine metal particles are interbonded and solidified. A portion of the empty space between the metal particles is filled with the graphene composite layer, creating an interconnected structure.

[0033] Furthermore, the structure may be one in which the surface of the fine metal particles is coated with graphene.

[0034] Pure, defect-free graphene possesses excellent physical properties, such as superior electrical conductivity and a high specific surface area. However, the irreversible phenomenon of self-aggregation significantly reduces the advantage of its high specific surface area.

[0035] On the other hand, three-dimensional porous graphene structures, in which pores are organically linked in three dimensions between faults and / or multiple layers of graphene sheets, exhibit relatively superior properties in electrochemical applications such as energy conversion and storage devices because self-aggregation is reduced, resulting in a relatively larger specific surface area and faster diffusion of electrons and ions. Furthermore, three-dimensional porous graphene structures have the advantage that pore properties (such as pore location and size) can also be controlled through the control of process variables during their manufacturing process.

[0036] Furthermore, the three-dimensional porous graphene structure can also have its electrical properties adjusted by changing the electronic structure of graphene through chemical doping, which involves adsorbing dissimilar materials such as metal particles, as in the graphene-metal particle composite according to the present invention.

[0037] On the other hand, there are no particular limitations on the method for manufacturing three-dimensional porous graphene structures, but methods utilizing hard templates or soft templates are mainly employed. Methods using hard templates include methods utilizing spherical polymers, methods utilizing metal oxide particles, and methods utilizing porous substrates such as nickel foam. Soft templates, on the other hand, have the advantage of being relatively easier to remove the template compared to hard templates, as they allow for the synthesis of materials with controlled pore sizes using self-assembling surfactant molecules.

[0038] Furthermore, after forming a polymer coating layer, a stabilization reaction can be induced so that the carbon atoms within the polymer have a hexagonal ring arrangement, and then carbonization can be performed at high temperatures to produce a three-dimensional porous graphene structure. Specific examples of the polymer include poly(methyl methacrylate) (PMMA), polystyrene (PS), polyimide (PI), polyetherimide (PEI), and Kapton film, but the polymer is not necessarily limited to these. Any polymer that can act as a carbon source to form graphene by carbonization at high temperatures is acceptable, and there are no special restrictions on its structure, molecular weight, or glass transition temperature.

[0039] The metal particles that are compounded with the graphene to form a hybrid graphene composite include silver (Ag), silicon (Si), and silicon carbide (Si2C, SiC, or SiC2). X ), silicon oxide (SiO or SiO2 containing SiO2) X ), silicon composite oxide (Si-Mg x SiO xThe fine particles may consist of metals or semiconductors selected from the group consisting of ), magnesium metasilicate (enstatite, MgSiO3), forsterite (forsterite, Mg2SiO4), gold (Au), platinum (Pt), palladium (Pd), aluminum (Al), zinc (Zn), silver alloy (Ag alloy), copper (Cu) coated with silver (Ag), and silver (Ag) coated with copper (Cu). Furthermore, the fine particles may be metal or semiconductor particles comprising a core particle made of one of the metals or semiconductors and a coating layer made of a different material from the core particle (for example, silver-coated copper particles, copper-coated silver particles, oxide-coated silicon particles, composite oxide-coated silicon particles, etc.), but are not necessarily limited to the aforementioned metal particles.

[0040] Taking silver (Ag) particles as an example among the aforementioned metal particles, the silver (Ag) particles dissolve in lithium (Li) and lower the energy required for lithium crystallization. This causes lithium to generate pores and grow more uniformly, rather than unevenly, ultimately contributing to improved performance of lithium-ion batteries.

[0041] As a method for manufacturing the hybrid graphene composite by compounding graphene and metal particles, it is also possible to uniformly mix and compound the three-dimensional porous graphene structure and metal particles through a stirring process such as ball milling. However, more preferably, the mixture in which the three-dimensional porous graphene structure and metal particles are uniformly mixed is irradiated with light to sinter the mixture, thereby manufacturing a hybrid graphene composite having a three-dimensional network structure in which interconnections between metal particles, interconnections between graphene sheets, and interconnections between metal particles and graphene sheets are organically achieved.

[0042] This can also be applied to lithium-ion batteries, which are all-solid-state batteries that include a solid electrolyte layer. The all-solid-state battery containing the negative electrode active material made of the hybrid graphene composite may include a positive electrode containing a positive electrode current collector and a positive electrode active material layer, a solid electrolyte layer, and a negative electrode containing a negative electrode current collector and a negative electrode active material layer made of the hybrid graphene composite.

[0043] In this case, the positive electrode active material layer may include one or more positive electrode active materials selected 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), but the constituent materials are not necessarily limited to the positive electrode active material.

[0044] Furthermore, the type of solid electrolyte constituting the solid electrolyte layer is not particularly limited, but it can include sulfide-based solid electrolytes, such as Li2S-P2S5-LiI, Li2S-P2S5-LiCl, Li2S-P2S5-LiBr, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, and Li2S-SiS2 、 One or more selected from the group consisting of Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-GeS2, and Li2S-SiS2-Li3PO4. in It's okay to have it.

[0045] The present invention will be described in more detail below with reference to embodiments.

[0046] The embodiments described herein can be modified into various other forms, and the scope of this specification is not to be interpreted as being limited to the embodiments detailed below.

[0047] The embodiments described herein are provided to give a more complete explanation of this specification to a person of average knowledge in the art.

[0048] Figure 1a is a scanning electron microscope (SEM) image showing silver particles (Ag) before undergoing a photothermal irradiation process to manufacture the hybrid graphene composite, which is the negative electrode active material contained in the negative electrode for a solid-state battery according to the present invention.

[0049] Referring to Figure 1a, the silver (Ag) particles before photothermal irradiation have a spherical shape and a particle diameter of approximately 5 μm.

[0050] Figure 1b is a scanning electron microscope (SEM) image showing silver particles (Ag) after the photothermal irradiation process.

[0051] Referring to Figure 1b, it can be seen that the surface of the silver (Ag) particles was melted using photothermal irradiation and then solidified by bonding with adjacent particles, while some particles were not bonded, resulting in the formation of empty spaces.

[0052] Figure 1c is a scanning electron microscope (SEM) image showing a porous graphene structure (3D nanoporous graphene) before undergoing a photothermal irradiation process for manufacturing a hybrid graphene composite, which is a negative electrode active material contained in the negative electrode for a lithium-ion battery according to the present invention.

[0053] Referring to Figure 1c, it can be seen that the multilayer graphene has a three-dimensional structure in which it overlaps or is bent.

[0054] Figure 1d is a scanning electron microscope (SEM) image showing a hybrid graphene composite for a negative electrode active material of an all-solid-state battery according to the present invention, which was manufactured by performing a photothermal irradiation process on a mixture of a three-dimensional porous graphene structure and silver particles (Ag) according to an embodiment of the present application.

[0055] Referring to Figure 1d, an embodiment of the present application shows a fixed structure in which fine metal particles can be simultaneously bonded to the surface and interior of the graphene composite layer by photochemical, photothermal irradiation, or heat treatment, and at the same time the fine metal particles can be interbonded and solidified.

[0056] Figure 1e is a conceptual diagram showing a structure in which graphene produced by photochemical, photothermal irradiation, or heat treatment as described in d above is fixed in the empty spaces of silver (Ag) fine particles in an embodiment of the present application.

[0057] Figure 1e is a conceptual diagram showing a structure in which graphene produced by photochemical, photothermal irradiation, or heat treatment is fixed in the empty spaces of silver (Ag) microparticles. The silver (Ag) microparticles can be bound to the interior and exterior of the graphene composite layer, and although not shown in the conceptual diagram, some of the micrometal particles can be interbonded and solidified due to the irregular positioning of the silver (Ag) microparticles.

[0058] Furthermore, the silver (Ag) fine metal particles can have a graphene coating formed on their surface by photochemical, photothermal irradiation, or heat treatment. Figure 1e illustrates the graphene coating structure on the particle surface in a mesh pattern.

[0059] While existing graphene requires complex processes, including high-temperature steps, photochemical, photothermal irradiation, or heat-treated synthesized graphene can be synthesized relatively easily in a single step.

[0060] Figure 2 is a graph showing the current measurement results for the hybrid graphene composite (Graphene-Ag electrode), graphene electrode, and metal electrode (Gold electrode) for all-solid-state battery negative electrode active material according to the present invention, depending on the concentration of the electrochemical measurement substance (p-Aminophenol, PAP).

[0061] For each electrode, the size of the current signal gradually increases with the PAP concentration.

[0062] 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 compared to the metal electrode, becomes even larger, and it can be seen that the signal of the hybrid graphene composite electrode with a small specific resistance of the graphene electrode is measured to be even larger.

[0063] Figure 3 is a graph showing a comparison of the current values of the same concentration (10 -3 mM) of PAP for the hybrid graphene (Hybrid Graphene), graphene (Graphene), and metal (Metal(Au)) for the negative electrode active material of the all-solid-state battery according to the present invention.

[0064] Referring to Figure 3, it is a graph showing the difference in the current signals measured for the same concentration of PAP for the hybrid graphene electrode (graphene-metal composite) and the metal electrode and the graphene electrode of the negative electrode active material electrode for the all-solid-state battery. It can be confirmed that the size of the signal measured by the graphene-metal composite electrode at the same concentration is very large compared to the reference electrode. Therefore, it can be seen that the current signal of the graphene-metal composite electrode of the present invention generates a larger signal compared to the reference electrode, and the SNR (Signal to Noise Ration) is larger compared to the reference electrode.

[0065] Figure 4 is a real-time graph showing the measurement of various concentrations of the electrochemical measurement substance (PAP) using the hybrid graphene electrode for the negative electrode of the all-solid-state battery according to the present invention.

[0066] Figure 5 is an example of an all-solid-state battery including the negative electrode for the all-solid-state battery according to the present invention, and is a cross-sectional schematic view of an all-solid-state battery including a positive electrode containing a positive electrode active material (NMC), a sulfide-based solid electrolyte layer, a negative electrode current collector (SUS), and a negative electrode active material layer containing a negative electrode active material composed of the hybrid graphene composite.

[0067] Figure 6 is a photograph showing cross-sections of the charging (a) and discharging (b) states of the negative electrode for an all-solid-state battery containing the hybrid graphene composite of the present invention.

[0068] Existing negative electrodes suffer from the problem of non-uniform lithium deposition, leading to pore formation and dendrite deposition. However, silver micro-metal particles dissolve in the lithium, lowering the energy required for lithium crystallization, thus allowing the lithium to grow uniformly. Furthermore, graphene prevents the lithium metal from growing and coming into direct contact with the solid electrolyte, thus preventing the solid electrolyte from decomposing and improving durability.

[0069] It can act as a three-dimensional host where lithium metal is deposited, and as a protective layer to protect the solid electrolyte, thereby improving durability.

[0070] Figure 7 shows the hybrid graphene anode fabricated according to the present invention (left) and a coin cell battery fabricated using it (right).

[0071] The present invention described above is not limited by the embodiments and accompanying drawings, and it will be obvious to those with ordinary skill in the art to which the present invention pertains that various substitutions, modifications, and changes are possible without departing from the technical spirit of the present invention. This application includes the following aspects: [Section 1] The negative electrode active material consists of a graphene composite having a structure in which multiple microparticles and multilayer graphene are mixed. The fine particles are metal or semiconductor particles, which are bound to the surface or interior of the multilayer graphene, and some of the fine particles are interbonded and solidified. The aforementioned multilayer graphene has a three-dimensional structure in which multiple layers of graphene are stacked and bent in any direction. The fine particles are bound to the surface or interior of the graphene. A negative electrode for a lithium-ion battery containing hybrid graphene, characterized in that a portion of the spaces between the fine particles are filled with the graphene composite, creating an interconnected structure. [Section 2] A negative electrode for a lithium-ion battery comprising the hybrid graphene described in item 1, characterized in that the surface of the fine particles is coated with graphene. [Section 3] A negative electrode for a lithium-ion battery containing the hybrid graphene described in item 1, characterized in that the surface of the fine particles is melted and solidified with graphene, and the fine particles and graphene are bonded together to form a three-dimensional nanostructure. [Section 4] The negative electrode for a lithium-ion battery comprising the hybrid graphene described in item 1, characterized in that the graphene composite is produced by a photochemical, photothermal irradiation, or heat treatment process. [Section 5] The aforementioned fine particles are silver (Ag), silicon (Si), and silicon carbide (Si 2 C, SiC, or SiC 2 SiC containing X ), silicon oxide (SiO or SiO 2 SiO X ), silicon composite oxide (Si-Mg x SiO x ), magnesium metasilicate (enstatite, MgSiO 3 ), forsterite (Mg 2 SiO 4 A negative electrode for a lithium-ion battery comprising the hybrid graphene described in item 1, characterized in that it is made of a metal or semiconductor selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), aluminum (Al), zinc (Zn), silver alloy (Ag alloy), copper (Cu) coated with silver (Ag), and silver (Ag) coated with copper (Cu). [Section 6] The graphene composite is a three-dimensional porous graphene structure. A negative electrode for a lithium-ion battery containing the hybrid graphene described in item 1, characterized in having a network structure formed by the interconnection of the aforementioned fine particles. [Section 7] A positive electrode including a positive electrode current collector and a positive electrode active material layer, A solid electrolyte layer, A lithium-ion battery comprising a negative electrode as described in any one of items 1 to 6. [Section 8] The lithium-ion battery according to claim 7, characterized in that the positive electrode active material layer comprises one or more positive electrode active materials selected 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). [Section 9] The solid electrolyte layer is 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-GeS 2 , and Li 2 S-SiS 2 -Li 3 PO 4 The lithium-ion battery according to item 7, characterized by containing one or more solid electrolytes selected from the group consisting of the following.

Claims

1. The negative electrode active material comprises a graphene composite having a structure in which multiple microparticles and multilayer graphene are mixed. The fine particles are metal or semiconductor particles, which are bound to the surface or interior of the multilayer graphene, and some of the fine particles are interbonded and solidified. The aforementioned multilayer graphene has a three-dimensional structure in which multiple layers of graphene are stacked and bent in any direction. The fine particles are bound to the surface or interior of the graphene. A portion of the space between the aforementioned fine particles is filled with the graphene composite, forming an interconnected structure. The anode for a lithium-ion battery, comprising hybrid graphene, is characterized in that the fine particles are made of a metal or semiconductor selected from the group consisting of silicon (Si), silicon carbide (Si₂C, SiC, or SiC₂ containing SiC₂), silicon oxide (SiO or SiO₂ containing SiO₂), silicon composite oxide (Si-Mg₂x₂SiO₂x₂), magnesium metasilicate (enstatite, MgSiO₃), forsterite (forsterite, Mg₂SiO₄), platinum (Pt), palladium (Pd), aluminum (Al), and zinc (Zn).

2. A negative electrode for a lithium-ion battery containing hybrid graphene according to claim 1, characterized in that the surface of the fine particles is coated with graphene.

3. The negative electrode for a lithium-ion battery containing hybrid graphene according to claim 1, characterized in that the surface of the fine particles is melted and solidified with graphene, and the fine particles and graphene are bonded together to form a three-dimensional nanostructure.

4. The negative electrode for a lithium-ion battery comprising the hybrid graphene according to claim 1, characterized in that the graphene composite is produced by a photochemical, photothermal irradiation, or heat treatment process.

5. The graphene composite is a three-dimensional porous graphene structure. A negative electrode for a lithium-ion battery containing hybrid graphene according to claim 1, characterized in that it has a network structure formed by the interconnection of the fine particles.

6. A positive electrode including a positive electrode current collector and a positive electrode active material layer, A solid electrolyte layer, A lithium-ion battery comprising a negative electrode according to any one of claims 1 to 5.

7. The lithium-ion battery according to claim 6, characterized in that the positive electrode active material layer includes one or more positive electrode active materials selected 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).

8. The lithium-ion battery according to claim 6, characterized in that the solid electrolyte layer contains one or more solid electrolytes selected from the group consisting of Li2S-P2S5-LiI, Li2S-P2S5-LiCl, Li2S-P2S5-LiBr, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-GeS2, and Li2S-SiS2-Li3PO4.

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