Negative electrode for lithium metal battery and lithium metal battery comprising same

Abstract

The present invention relates to a negative electrode for a lithium metal battery and a lithium metal battery comprising same, the negative electrode comprising: a negative electrode current collector; and a negative electrode protective layer on the negative electrode current collector, wherein the negative electrode protective layer may comprise a polymer matrix and lithiophilic metal particles dispersed in the polymer matrix.

Description

Negative electrode for a lithium metal battery and a lithium metal battery including the same

[0001] The invention relates to a negative electrode for a lithium metal battery and a lithium metal battery including the same.

[0002]

[0003] Currently commercially available lithium secondary batteries mainly use carbon-based negative electrode active materials such as graphite. Carbon-based negative electrode active materials do not change in volume during charging and discharging, so the stability of lithium secondary batteries is high. The theoretical electric capacity of graphite is small, about 372 mAh / g.

[0004] Lithium metal can be used as a negative electrode active material. The theoretical electric capacity of lithium metal is approximately 3,860 mAh / g, which is larger than that of graphite. During charging and discharging, dendrites may form on the surface of lithium metal due to side reactions with the electrolyte, and the growth of these dendrites can cause a short circuit between the positive and negative electrodes. Consequently, the lifespan characteristics of lithium metal batteries containing lithium metal may be degraded.

[0005] A method is required to improve the lifespan characteristics of lithium metal batteries containing lithium metal.

[0006]

[0007] One aspect is to provide a cathode in which lithium dendrite formation is suppressed.

[0008] Another aspect is providing a cathode with improved ion conductivity.

[0009] Another aspect is to provide a lithium metal battery with improved cycle characteristics by providing a cathode with enhanced ion conductivity and suppressed lithium dendrite formation.

[0010]

[0011] According to one embodiment, a negative electrode for a lithium metal battery is provided, comprising: a negative electrode current collector; and a negative electrode protective layer on the negative electrode current collector; wherein the negative electrode protective layer comprises a polymer matrix and lithium-affinity metal particles dispersed within the polymer matrix.

[0012] According to another embodiment, a lithium metal battery is provided, comprising: an anode layer including an anode current collector and an anode active material layer on the anode current collector; a cathode layer; and an electrolyte layer disposed between the anode layer and the cathode layer, wherein the cathode layer comprises the cathode described above.

[0013]

[0014] According to one aspect, it is possible to provide a lithium metal battery with improved cycle characteristics by employing a negative electrode in which lithium dendrite formation is suppressed and ion conductivity is enhanced.

[0015]

[0016] FIG. 1 is a cross-sectional view of a lithium metal battery according to an exemplary embodiment.

[0017] Figure 2 is a conceptual diagram illustrating the stacking of lithium metal on a current collector at the negative electrode of a lithium metal battery.

[0018] Figure 3 is a conceptual diagram illustrating the stacking of lithium metal on a current collector at the negative electrode of a lithium metal battery including a protective layer.

[0019] FIG. 4 is a cross-sectional view of a negative electrode for a lithium metal battery according to an exemplary embodiment.

[0020] FIG. 5 is a conceptual diagram illustrating the stacking of lithium metal on a current collector in a negative electrode for a lithium metal battery according to an exemplary embodiment.

[0021] FIG. 6 is a cross-sectional view of a negative electrode for a lithium metal battery according to another exemplary embodiment.

[0022] FIG. 7 is a cross-sectional view of a negative electrode for a lithium metal battery according to another exemplary embodiment.

[0023] FIG. 8 is a cross-sectional view of a negative electrode for a lithium metal battery according to another exemplary embodiment.

[0024] FIG. 9 is a cross-sectional view of a lithium metal battery according to another exemplary embodiment.

[0025] FIG. 10 is a graph showing the capacity retention rate of lithium metal batteries according to Example 1, Comparative Example 1, and Comparative Example 2.

[0026]

[0027] The present inventive concept described below is subject to various modifications and may have various embodiments, and specific embodiments are illustrated in the drawings and described in detail. However, this is not intended to limit the present inventive concept to specific embodiments and should be understood to include all modifications, equivalents, or substitutions that fall within the scope of the description of the present inventive concept.

[0028] The terms used below are used merely to describe specific embodiments and are not intended to limit the creative concept. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the following, terms such as “comprising” or “having” are intended to indicate the existence of the features, numbers, steps, actions, components, parts, components, materials, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, components, materials, or combinations thereof. As used below, “ ” may be interpreted as “and” or “or” depending on the context.

[0029] In the drawings, thicknesses have been enlarged or reduced to clearly represent various layers and regions. Throughout the specification, the same reference numerals have been used for similar parts. Throughout the specification, when a part such as a layer, film, region, or plate is described as being “on” or “above” another part, this includes not only cases where it is directly above another part but also cases where there is another part in between. Throughout the specification, terms such as “first,” “second,” etc., may be used to describe various components, but the components should not be limited by these terms. In this specification and drawings, components having substantially the same functional configuration are referred to by the same reference numerals to avoid redundant descriptions.

[0030] In the present disclosure, the “size” of a particle is, for example, the “particle diameter” of the particle. The “particle diameter” of the particle represents the average diameter when the particle is spherical and represents the average major axis length when the particle is non-spherical. The particle diameter of the particle can be measured using a particle size analyzer (PSA). The “particle diameter” of the particle is, for example, the average particle diameter. The average particle diameter is, for example, the median particle diameter (D50). The median particle diameter (D50) is the particle size corresponding to the 50% cumulative volume calculated from the side of the particle having a small particle size in the particle size distribution measured, for example by laser diffraction.

[0031] In the present disclosure, “metal” includes both metals and metalloids such as silicon and germanium in an elemental or ionic state.

[0032] In this disclosure, “alloy” means a mixture of two or more metals.

[0033] In the present disclosure, “anode active material” refers to an anode material capable of undergoing lithiation and delithiation.

[0034] In the present disclosure, “anode active material” refers to an anode material capable of undergoing lithiation and delithiation.

[0035] In the present disclosure, “lithiation” and “to lithiate” refer to the process of adding lithium to a positive electrode active material or a negative electrode active material.

[0036] In the present disclosure, “delithiation” and “to delithiate” refer to the process of removing lithium from a positive electrode active material or a negative electrode active material.

[0037] In this disclosure, “charge” and “to charge” refer to the process of providing electrochemical energy to a battery.

[0038] In this disclosure, “anode” and “cathode” refer to electrodes where electrochemical reduction and lithiation occur during the discharge process.

[0039] In this disclosure, “cathode” and “anode” refer to electrodes where electrochemical oxidation and delithiation occur during the discharge process.

[0040] A cathode according to exemplary embodiments, a lithium secondary battery including the same, and a method for manufacturing the same will be described in more detail below.

[0041] [Cathode for lithium metal battery and lithium metal battery including the same]

[0042] Referring to FIG. 1, a lithium metal battery (1000) according to one embodiment may include: a positive electrode layer (100) comprising a positive electrode current collector (110) and a positive electrode active material layer (120) on the positive electrode current collector (110); a negative electrode layer (200) comprising a negative electrode current collector (210) and a negative electrode protective layer (220) on the negative electrode current collector (210); and a solid electrolyte layer (300) disposed between the positive electrode layer (100) and the negative electrode layer (200).

[0043] The negative current collector (210) may provide a reference surface on which the negative protection layer (220) is disposed. The negative current collector (210) may comprise, for example, a material that does not react with lithium, that is, does not form any alloys or compounds with lithium. The material constituting the negative current collector (210) may comprise, for example, at least one metal selected from the group consisting of copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni). The thickness (t) of the negative current collector (210). 210 ) can be 1 to 20 μm, for example 5 to 15 μm, for example 7 to 10 μm.

[0044] The negative current collector (210) may be composed of one of the metals described above, or may include an alloy of two or more metals or a coating material. The negative current collector (210) is, for example, in the form of a plate or foil. In another embodiment, the negative current collector (210) may be omitted.

[0045] Referring to FIG. 2, lithium metal is deposited on a negative electrode current collector (210) during the charging process of a lithium metal battery. The deposited lithium metal can be used as a negative electrode active material. The theoretical electrical capacity of lithium metal is approximately 3,860 mAh / g, which is larger than that of graphite. During charging and discharging, lithium dendrites (LD) may form on the surface of the lithium metal due to side reactions with the electrolyte, and the growth of lithium dendrites (LD) can cause a short circuit between the positive and negative electrodes. Some of the grown lithium dendrites (LD) may detach from the lithium metal and form dead lithium (DL) that has lost its function as a lithium reservoir. Consequently, the lifespan characteristics of the lithium metal battery containing lithium metal may be degraded.

[0046] Referring to FIG. 3, the protective layer (PL) can be configured to allow lithium metal to grow between it and the negative electrode current collector (210) during charging of the lithium metal battery. The negative electrode coating layer (220) can serve to protect the lithium metal while simultaneously suppressing the deposition and growth of lithium dendrites (LD). Specifically, a lithium metal battery containing the protective layer (PL) can suppress the growth of lithium dendrites (LD) by allowing lithium (Li) derived from the positive electrode to pass through and uniformly electrodepositing lithium metal between the negative electrode current collector (210) and the protective layer (PL). The protective layer (PL) acts as a resistance layer when lithium (Li) passes through, which can reduce the lithium ion conductivity. Consequently, the lifespan characteristics of the lithium metal battery containing lithium metal may be degraded.

[0047] Referring to FIG. 4, a negative electrode for a lithium metal battery according to one embodiment comprises a negative electrode current collector (210) and a negative electrode protective layer (220) on the negative electrode current collector (210), and the negative electrode protective layer (220) may comprise a polymer matrix and lithium-affinity metal particles (LPMP) dispersed within the polymer matrix.

[0048] The polymer matrix and lithium-affinity metal particles (LPMP) can form composites of, for example, the cathode protection layer (220). The polymer matrix can, for example, maintain the shape of the cathode protection layer (220) and provide a space to disperse the lithium-affinity metal particles (LPMP) inside. The polymer matrix is, for example, carboxymethylcellulose (CMC), polyethylene glycol (PEG), polyethylene oxide (PEO), polyethylene glycol methacrylate (PEGMA), polyethylene glycol dimethacrylate (PEGDMA), polyethylene carbonate (PEC), polytrimethylene carbonate (PTMC), polypropylene carbonate (PPC), polyvinylidene fluoride (PVDF), polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP), polyacrylonitrile (PAN), It may include polyacrylic acid (PAA) or a combination thereof. Such a polymer matrix has excellent mechanical properties, so it can minimize resistance at the interface in contact with the electrolyte layer (300) and can physically suppress lithium dendrites (LD) that grow during the process of lithium electrodeposition by adhering to the lithium metal layer (230).

[0049] The polymer matrix may comprise, for example, poly(propylene carbonate, PPC), poly(vinylidene fluoride, PVDF), poly(vinylidene fluoride-co-hexafluoropropylene (PVDF-HFP), or a combination thereof. The polymer matrix may be, for example, poly(vinylidene fluoride-co-hexafluoropropylene (PVDF-HFP). Poly(vinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) may be a copolymer of poly(vinylidene fluoride, PVDF) and hexafluoropropylene (HFP). Polyvinylidene Poly(vinylidene fluoride-co-hexafluoropropylene, PVDF-HFP) has excellent chemical resistance, which can suppress side reactions between the cathode protection layer (220) and the electrolyte, and has high tensile strength, which is easy to physically suppress the growth of lithium dendrites (LD), and is more flexible than pure poly(vinylidene fluoride, PVDF), which can reduce the interfacial resistance between the electrolyte layer (300) and the cathode protection layer (220). As a result, a lithium metal battery containing a cathode protection layer (220) containing poly(vinylidene fluoride-co-hexafluoropropylene, PVDF-HFP) can have improved cycle characteristics.

[0050] The content of HFP in poly(vinylidene fluoride-co-hexafluoropropylene, PVDF-HFP) may be, for example, 20 wt% to 50 wt%, 25 wt% to 40 wt%, or 30 wt% to 35 wt%. When the content of HFP has the above range, the flexibility of the polymer matrix increases, and the interfacial resistance between the cathode protection layer (220) and the electrolyte layer (300) may be reduced.

[0051] The content of HFP in poly(vinylidene fluoride-co-hexafluoropropylene, PVDF-HFP) may be, for example, 5 wt% to 30 wt%, 10 wt% to 25 wt%, or 20 wt% to 25 wt%. When the content of HFP has the above range, the mechanical strength of the polymer matrix increases, which can physically inhibit the growth of lithium dendrites (LD).

[0052] The cathode protection layer (220) may include, for example, at least two layers containing PVDF-HFP with different HFP contents. The physical boundaries between the two or more layers may not be distinct. The HFP content of the cathode protection layer (220) may be, for example, higher in the region in contact with the cathode current collector (210) than in the region in contact with the electrolyte layer (300). In this case, the interface characteristics between the electrolyte layer (300) and the cathode protection layer (220) are excellent, and the cathode protection layer (220) is provided with an excellent effect of suppressing the formation of lithium dendrites (LD).

[0053] The polymer matrix may comprise 60 to 90 parts by weight per 100 parts by weight of the cathode protection layer (220). If the polymer matrix is ​​less than the above range, it is difficult to maintain the shape of the cathode protection layer (220) consistently, and if it exceeds the above range, the content of the relatively lithium-affinity metal particles (LPMP) may decrease, and the ion conductivity of the cathode protection layer (220) may decrease.

[0054] Lithium-affinity metal particles (LPMP) may be in the form of particles, for example. The average particle size of the lithium-affinity metal particles (LPMP) may be, for example, 5 nm to 900 nm, 10 nm to 500 nm, or 20 nm to 200 nm. According to one embodiment of the present creative idea, a plurality of lithium-affinity metal particles (LPMP) may exist within the negative electrode protective layer (220) in the form of aggregates that are aggregated together. The average particle size of the lithium-affinity metal particles (LPMP) may be defined as the average size of the aggregates. By having the lithium-affinity metal particles (LPMP) have an average particle size within this range, the ion conductivity of lithium (Li) penetrating the negative electrode protective layer (220) may be improved. Consequently, the cycle characteristics of the lithium metal battery (1000) may be further improved.

[0055] The negative electrode protective layer (220) may contain 10 to 40 parts by weight, 15 to 35 parts by weight, or 20 to 30 parts by weight of lithium-affinity metal particles (LPMP) per 100 parts by weight of a polymer matrix. By having the lithium-affinity metal particles (LPMP) in the negative electrode protective layer (220) within this content range, the ion conductivity of lithium (Li) passing through the negative electrode protective layer (220) can be improved. Consequently, the cycle characteristics of the lithium metal battery (1000) can be further improved.

[0056] Lithium-affinity metal particles (LPMP) may include, for example, aluminum (Al), silver (Ag), copper (Cu), gold (Au), titanium (Ti), nickel (Ni), cobalt (Co), iron (Fe), manganese (Mn), magnesium (Mg), potassium (K), chromium (Cr), tin (Sn), vernatium (V), zinc (Zn), or a combination thereof. These lithium-affinity metal particles can increase the ionic conductivity of the negative electrode protective layer (220), thereby improving the deposition rate of lithium (Li). As a result, the cycle characteristics of the lithium metal battery (1000) can be further improved. The lithium-affinity metal particles (LPMP) may include silver (Ag), nickel (Ni), cobalt (Co), iron (Fe), zinc (Zn), or a combination thereof.

[0057] The cathode protection layer (220) may further include, for example, a binder. By including a binder in the cathode protection layer (220), the bonding strength between the polymer matrix and the lithium-affinity metal particles (LPMP) can be further improved. By including a binder in the cathode protection layer (220), the cathode protection layer (220) can maintain a constant shape and its mechanical strength can be improved, and direct contact between the electrolyte and the lithium metal layer (230) can be blocked more effectively.

[0058] The binder may include, for example, a non-conductive binder or a conductive binder. The conductive binder may include, for example, an ion-conductive binder, an electron-conductive binder, or a combination thereof. Binders are, for example, polytetrafluoroethylene (PTFE), polyamide-imide (PAI), polyimide (PI), styrene-butadiene rubber (SBR), (meth)acrylated styrene-butadiene rubber, polyethylene oxide (PEO), polyphosphazene, poly(meth)acrylonitrile (PAN), (meth)acrylic resin, phenol resin, epoxy resin, polyvinyl alcohol (PVA), polyvinylidene fluoride (PVDF), and polyvinylidene It may include a polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), or a combination thereof.

[0059] The binder content may be, for example, 1 to 30 parts by weight, 5 to 30 parts by weight, or 10 to 30 parts by weight of binder per 100 parts by weight of polymer matrix. The binder content included in the cathode protection layer (220) may be, for example, 1 to 25 wt% or 5 to 20 wt% with respect to the total weight of the cathode protection layer (220). By including a binder within this range in the cathode protection layer (220), the cycle characteristics of the lithium metal battery including the cathode protection layer (220) may be further improved.

[0060] The cathode protective layer (220) may further include, for example, a metal oxide. The cathode protective layer (220) may simultaneously include, for example, yellowing polyacrylonitrile (SPAN) and a metal oxide. A protective layer that simultaneously includes yellowing polyacrylonitrile (SPAN) and a metal oxide is, for example, an organic-inorganic composite protective layer. By further including a metal oxide in the cathode protective layer (220), the strength and / or elasticity of the protective layer may be improved. Since the durability of the cathode protective layer (220) is improved, the precipitation and / or growth of lithium dendrites at the interface between the cathode protective layer (220) and the lithium metal layer (230) can be more effectively prevented. The cycle characteristics of a lithium metal battery including such a cathode protective layer (220) may be further improved.

[0061] The metal oxide may be in the form of particles, for example. The shape of the metal oxide particles is not particularly limited. The metal oxide particles may be, for example, spherical particles, plate-shaped particles, needle-shaped particles, or a combination thereof. The metal oxide particles may have an irregular shape, for example. The average particle size of the metal oxide may be, for example, 100 nm to 2 µm, 200 nm to 1 µm, or 400 nm to 1 µm. By having the metal oxide with a particle size in this range, the cycle characteristics of the lithium metal battery including the negative electrode protective layer (220) may be further improved. The metal oxide may be, for example, porous or non-porous. The metal oxide may be, for example, crystalline or amorphous.

[0062] Metal oxides may include, for example, Nb2O5, TiO2, Al2O3, SiO2, BaTiO3, MOF (Metal Organic Framework), POSS (Polyhedral Oligomeric Silsesquioxanes), Li2CO3, Li3PO4, Li2O, montmorillonite, ZrO2, CeO2, Mn3O4, or combinations thereof, but are not necessarily limited to these, and any metal oxide used in the relevant technical field is acceptable.

[0063] Metal oxides may, for example, possess lithium affinity. Metal oxides with lithium affinity can react with lithium ions during the charging and discharging process of a lithium metal battery. Metal oxides may include, for example, pseudo-capacitive oxides that react with lithium to form lithium metal oxides. Oxides providing pseudocapacitance may be, for example, Nb2O5, TiO2, etc. Nb2O5 may have a crystal structure belonging to the orthorhombic system, for example. Nb2O5 reacts with lithium ions, for example, during the charging process of a lithium battery, Li x Nb2O5(0 <x<1)를 형성할 수 있다. 의사용량성 산화물은 예를 들어 의사커패시터(pseudo capacitor)로 작용함에 의하여 보호층 내에 리튬을 저장 및 / 또는 분산시키는 역할을 수행할 수 있다. 의사용량성 산화물을 포함하는 보호층의 리튬 이온 전도 특성이 향상되고 리튬의 편재화(localization)가 방지될 수 있다.

[0064] The metal oxide content may be, for example, 5 to 60 parts by weight, 10 to 50 parts by weight, 10 to 40 parts by weight, or 10 to 30 parts by weight of metal oxide per 100 parts by weight of yellowing polyacrylonitrile. The metal oxide content included in the protective layer may be, for example, 1 to 40 wt%, 5 to 30 wt%, or 5 to 20 wt% based on the total weight of the protective layer. By including metal oxides within this range in the protective layer, the cycle characteristics of the lithium metal battery including the protective layer may be further improved.

[0065] The cathode protective layer (220) may further include a carbon-based material. The cathode protective layer (220) may include, for example, lithium-affinity metal particles (LPMP) and a carbon-based material. The cathode protective layer (220) may include, for example, lithium-affinity metal particles (LPMP), a metal oxide, and a carbon-based material. By further including a carbon-based material in the protective layer, the dispersibility of the lithium-affinity metal particles (LPMP) and / or metal oxide may be improved. Thus, the precipitation and / or growth of localized lithium dendrites at the interface between the protective layer and the lithium metal layer (230) can be prevented more effectively. The carbon-based material may act as a carbon-based dispersant. The carbon-based material may be, for example, a carbon-based conductive material. By including a carbon-based material in the protective layer, the internal resistance of the protective layer may be reduced and conductivity may be imparted to the protective layer. The carbon-based material may be, for example, amorphous carbon. By including amorphous carbon in the negative electrode protective layer (220), lithium ions can move more rapidly within the negative electrode protective layer (220) through the surface of the amorphous carbon. The carbon-based material may be porous or non-porous. The carbon-based material may be in the form of particles, for example. The carbon-based material may be, for example, spherical particles, plate-shaped particles, needle-shaped particles, or a combination thereof. The carbon-based material particles may have an irregular shape, for example. The average particle size of the carbon-based material may be, for example, 10 nm to 500 nm, 10 nm to 300 nm, 10 nm to 200 nm, 10 nm to 100 nm, 10 nm to 50 nm, 30 nm to 50 nm, or 40 nm to 50 nm. By having the carbon-based material have a particle size within this range, the cycle characteristics of the lithium metal battery including the protective layer may be further improved. The particle size of carbon-based materials can be measured, for example, by laser diffraction, scanning electron microscopy, transmission electron microscopy, or atomic force microscopy.

[0066] Carbon-based materials may include, for example, carbon black, acetylene black, Denka black, Ketchen black, carbon nanotubes, carbon nanofibers, carbon nanobelts, graphene, graphene oxide, fullerene, activated carbon, carbon fibers, or combinations thereof, but are not necessarily limited to these, and any material used as a carbon-based material in the relevant technical field is acceptable.

[0067] The carbon-based material content may be, for example, 10 to 100 parts by weight, 30 to 100 parts by weight, 50 to 100 parts by weight, or 70 to 90 parts by weight of carbon-based material with respect to 100 parts by weight of polymer matrix. The carbon-based material content may be, for example, 1 to 50 wt%, 10 to 50 wt%, or 20 to 40 wt% with respect to the total weight of the protective layer. By including a metal oxide within this range in the negative electrode protective layer (220), the cycle characteristics of the lithium battery including the negative electrode protective layer (220) may be further improved.

[0068] The negative electrode protective layer (220) may, for example, comprise 5 to 40 parts by weight of a metal oxide and 50 to 100 parts by weight of a carbon-based material per 100 parts by weight of yellowing polyacrylonitrile. By having such a composition of the negative electrode protective layer (220), the cycle characteristics of the lithium metal battery including the protective layer can be further improved.

[0069] The thickness of the negative electrode protective layer (220) may be, for example, 0.1 μm to 30 μm, 1 μm to 20 μm, or 1 μm to 5 μm. If the thickness of the negative electrode protective layer (220) is too small, it may be difficult to perform the function of the protective layer. If the thickness of the negative electrode protective layer (220) increases excessively, the internal resistance increases and the energy density of the lithium metal battery may decrease.

[0070] Referring to FIG. 5, a negative electrode for a lithium metal battery according to another embodiment may further include a lithium metal layer (230) disposed between a negative electrode current collector (210) and a negative electrode protection layer (220).

[0071] The lithium metal layer (230) may include lithium or a lithium alloy. Since the lithium metal layer (230) is a metal layer containing lithium, it may function as, for example, a lithium reservoir. The lithium alloy may be, for example, a Li-Al alloy, a Li-Sn alloy, a Li-In alloy, a Li-Ag alloy, a Li-Au alloy, a Li-Zn alloy, a Li-Ge alloy, a Li-Si alloy, but is not limited to these; any alloy used as a lithium alloy in the relevant technical field may be possible. The lithium metal layer (230) may be composed of one of these alloys or lithium, or may be composed of various types of alloys. The lithium metal layer (230) may be, for example, a plated layer. The lithium metal layer (230) may be deposited between the negative electrode protection layer (220) and the negative electrode current collector (210) during the charging process of a lithium metal battery, for example.

[0072] The thickness of the lithium metal layer (230) is not particularly limited, but may be, for example, 1 μm to 500 μm, 1 μm to 200 μm, 1 μm to 150 μm, 1 μm to 100 μm, or 1 μm to 50 μm. If the thickness of the lithium metal layer (230) is excessively thin, it may be difficult for the lithium metal layer (230) to perform the role of a lithium reservoir. If the thickness of the lithium metal layer (230) is excessively thick, the mass and volume of the lithium metal battery increase, and the cycle characteristics of the lithium metal battery may deteriorate. In another embodiment, the lithium metal layer (230) may be provided, for example, between the negative electrode current collector (210) and the negative electrode protection layer (220) before assembly of the lithium metal battery. When a lithium metal layer (230) is placed between a negative electrode current collector (210) and a negative electrode protective layer (220) before assembly of a lithium metal battery, the lithium metal layer (230) acts as a lithium reservoir because it is a metal layer containing lithium. For example, a lithium foil may be placed between a negative electrode current collector (210) and a negative electrode protective layer (220) before assembly of a lithium metal battery.

[0073] The lithium metal layer (230) can be composed mainly of lithium (i.e., metallic lithium). During discharge, the lithium in the lithium metal layer (230) can be ionized and move to the positive electrode layer (100). In other words, lithium can be used as a negative electrode active material in a lithium metal battery. In addition, since the negative electrode protective layer (220) covers the lithium metal layer (230), the negative electrode protective layer (220) can protect the lithium metal layer (230) and at the same time suppress the precipitation growth of lithium dendrites. Therefore, the negative electrode protective layer (220) can suppress short circuits and capacity degradation of the lithium metal battery and improve the cycle characteristics of the lithium metal battery.

[0074] When a lithium metal layer (230) is formed by charging after assembly of a lithium metal battery, the negative electrode layer (200), that is, the negative electrode current collector (210) and the negative electrode coating layer (220) and the region between them may be a Li-free region that does not contain lithium (Li) in the initial state or after complete discharge of the lithium metal battery.

[0075] Referring to FIG. 6, a negative electrode for a lithium metal battery according to another embodiment may further include a carbon layer (240) disposed on one or both sides of a negative electrode current collector (210). By additionally disposing of a carbon layer on the negative electrode current collector (210), corrosion of the metal of the negative electrode current collector (210) is prevented, and a lithium metal layer (230) can be deposited relatively uniformly on the negative electrode current collector (210). The thickness of the carbon layer (240) may be, for example, 1 μm to 5 μm, 1 μm to 4 μm, or 1 μm to 3 μm. If the thickness of the carbon layer (240) is excessively thin, the effect may be negligible. If the thickness of the carbon layer (240) is excessively thick, the energy density of the lithium metal battery may decrease. The carbon layer (240) may include amorphous carbon, crystalline carbon, etc. The thickness of the negative current collector (210), which includes the negative current collector (210) and optionally a carbon layer (240), may be, for example, 10 μm to 50 μm, 10 μm to 40 μm, or 10 μm to 30 μm.

[0076] Referring to FIG. 7, a negative electrode for a lithium metal battery according to another embodiment comprises a negative electrode current collector (210); a negative electrode protective layer (220) on the negative electrode current collector (210), wherein the negative electrode protective layer (220) may be arranged to extend to at least one side of the negative electrode current collector (210).

[0077] Referring to FIG. 8, a negative electrode for a lithium metal battery according to another embodiment comprises a negative electrode current collector (210); a negative electrode protective layer (220) on the negative electrode current collector (210); and a lithium metal layer (230) between the negative electrode current collector (210) and the negative electrode protective layer (220), wherein the negative electrode protective layer (220) may be disposed to extend to at least one side of the lithium metal layer (230) and / or the negative electrode current collector (210). The negative electrode protective layer (220) may extend to the side of the negative electrode current collector (210) by completely covering the lithium metal layer (230). By extending the negative electrode protective layer (220) to at least one side of the lithium metal layer (230) and / or the negative electrode current collector (210), the lithium metal layer (230) can be protected more effectively.

[0078] The positive current collector (110) can provide a reference surface on which the positive active material layer (120) is placed. The positive current collector (110) may include, for example, a plate or foil comprising indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof.

[0079] Meanwhile, unlike as illustrated in FIG. 1, in another embodiment, the positive current collector (110) may be omitted. Although not illustrated, a carbon layer with a thickness of 0.1 to 4 μm may be further disposed between the positive current collector (110) and the positive active material layer (120) to increase the bonding strength between the positive current collector (110) and the positive active material layer (120).

[0080] The positive active material layer (120) may include a positive active material, a solid electrolyte, a conductive material, and a binder. The positive active material may include a material capable of reversibly absorbing and desorbing lithium ions. The positive active material may include a plurality of particles. The positive active material may include, for example, lithium transition metal oxides such as lithium cobalt oxide (LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium manganate, and lithium iron phosphate, nickel sulfide, copper sulfide, lithium sulfide, iron oxide, or vanadium oxide, but is not necessarily limited to these. Each positive active material may be alone or a mixture of two or more types.

[0081] Lithium transition metal oxides are, for example, Li a A 1-b B b D2(0.90≤a≤1, 0≤b≤0.5), Li a E 1-b B b O 2-c D c (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05), LiE 2-b B b O 4-c D c (0≤b≤0.5, 0≤c≤0.05), Li a Ni 1-b-c Co b B c D α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2), Li a Ni 1-b-c Co b B c O 2-α F α(0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2), Li a Nor 1-b-c Mn b B c D α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α≤2), Li a Nor 1-b-c Mn b B c O 2-α F α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2), Li a Nor b E c G d O2(0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤0.1), Li a Nor b Co c Mn d GeO2(0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0.001≤e≤0.1), Li a NiG b O2(0.9≤a≤1, 0.001≤b≤0.1), Li a CoG b O2(0.90≤a≤1, 0.001≤b≤0.1), Li a MnG b O2(0.90≤a≤1, 0.001≤b≤0.1), Li a Mn2GbO4(0.90≤a≤1, 0.001≤b≤0.1), QO2, QS2, LiQS2, V2O5, LiV2O5, LiIO2, LiNiVO4, Li 3-f J2(PO4)3(0≤f≤2), Li 3-fIt is a compound represented by any one of Fe2(PO4)3 (0≤f≤2) or LiFePO4. In such compounds, the uppercase “A” is Ni, Co, Mn, or a combination thereof; the uppercase “B” is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; the uppercase “D” is O, F, S, P, or a combination thereof; the uppercase “E” is Co, Mn, or a combination thereof; the uppercase “F” is F, S, P, or a combination thereof; the uppercase “G” is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; the uppercase “Q” is Ti, Mo, Mn, or a combination thereof; the uppercase “I” is Cr, V, Fe, Sc, Y, or a combination thereof; and the uppercase “J” is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

[0082] The positive electrode active material may include, for example, a lithium salt of a transition metal oxide having a layered rock salt type structure among the lithium transition metal oxides described above. The "layered rock salt type structure" is, for example, a cubic rock salt type structure. <111> It is a structure in which oxygen and metal atomic layers are alternately and regularly arranged in a specific direction, thereby forming a two-dimensional plane for each atomic layer. The "cubic rock salt type structure" represents a sodium chloride (NaCl) type structure, which is a type of crystal structure; specifically, it exhibits a structure in which face-centered cubic lattices (fcc) formed by cations and anions, respectively, are offset from each other by half the ridge of the unit lattice. Lithium transition metal oxides having such a layered rock salt type structure are, for example, LiNi x Co y Al z O2(NCA) or LiNi x Co y Mn zO2(NCM) (0 <x<1,0<y<1, 0<z<1, x+y+z=1) 등의 삼원계 리튬전이금속산화물일 수 있다. 양극 활물질이 층상암염형 구조를 갖는 삼원계 리튬전이금속산화물을 포함하는 경우, 전고체 전지(1000)의 에너지 밀도가 커지고 열안정성이 향상될 수 있다.

[0083] The aforementioned compound contained in the positive electrode active material may be covered by a coating layer (not shown). The positive electrode active material may also be a mixture of the aforementioned compound and the compound to which the coating layer is added. Meanwhile, the coating layer added to the surface of the positive electrode active material may include, for example, oxides, hydroxides, oxyhydroxides, oxycarbonates, or hydroxycarbonates of the following coating elements. The compounds forming this coating layer are amorphous or crystalline. The coating elements included in the coating layer may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. The coating layer may include, for example, Li2O-ZrO2 (LZO). The method for forming the coating layer is selected within a range that does not adversely affect the physical properties of the positive electrode active material. The method for forming the coating layer is, for example, spray coating or immersion.

[0084] When the positive electrode active material contains nickel (Ni) as a ternary lithium transition metal oxide such as NCA or NCM, for example, the capacity density of the all-solid-state battery (1000) is increased, and the metal leaching of the positive electrode active material (PAM) in the charged state can be reduced. As a result, the cycle characteristics of the all-solid-state battery (1000) in the charged state are improved. Meanwhile, "cycle characteristics" is a characteristic that indicates the degree of deterioration of the all-solid-state battery (1000) due to charging and discharging of the all-solid-state battery (1000). An all-solid-state battery (1000) with high cycle characteristics has a small degree of deterioration due to charging and discharging, while an all-solid-state battery (1000) with low cycle characteristics may have a large degree of deterioration due to charging and discharging.

[0085] The positive active material may have particle shapes such as, for example, spheres or ellipsoids. The particle size and content of the positive active material are not particularly limited.

[0086] The solid electrolyte in the positive active material layer (120) may have a particle shape. The solid electrolyte in the positive active material layer (120) may be dispersed among the positive active materials. The solid electrolyte may include a sulfide-based solid electrolyte with excellent lithium ion conductivity characteristics. Sulfide-based solid electrolytes are, for example, Li2S-P2S5, Li2S-P2S5-LiX (where X is a halogen element), 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-P2S5-Z m S n (m, n are positive numbers, uppercase “Z” is one of Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q(p, q are positive numbers, uppercase “M” is one of P, Si, Ge, B, Al, Ga, In), Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x It may include at least one selected from (0≤x≤2).

[0087] Sulfide-based solid electrolytes are, for example, Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x It may be an argyrodite-type compound comprising one or more selected from (0≤x≤2). In particular, the sulfide-based solid electrolyte may be an argyrodite-type compound comprising one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I. The density of the argyrodite-type solid electrolyte may be 1.5 g / cc to 2.0 g / cc. By having a density of 1.5 g / cc or higher for the argyrodite-type solid electrolyte, the internal resistance of the all-solid-state battery is reduced, and defects such as penetration and short circuit of the solid electrolyte film due to lithium dendrite formation can be prevented. The elastic modulus of the solid electrolyte may be, for example, 15 GPa to 35 GPa.

[0088] The solid electrolyte in the positive active material layer (120) may have a smaller average particle size (D50) of intermediate particle size compared to the solid electrolyte in the solid electrolyte layer (300) described later. For example, the average particle size (D50) of the solid electrolyte included in the positive active material layer (120) may be 90% or less, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, or 20% or less of the average particle size (D50) of the solid electrolyte included in the solid electrolyte layer (300). Meanwhile, the average particle size (D50) may be a median diameter measured using a laser particle size distribution meter.

[0089] The positive active material layer (120) may include a conductive material. The conductive material may have conductivity without causing chemical changes in the all-solid-state battery (1000), thereby increasing the conductivity of the positive active material solid electrolyte. The conductive material may include a carbon-based material. The conductive material may include, for example, one or more selected from graphite, carbon black, acetylene black, carbon nanofibers, and carbon nanotubes.

[0090] The positive active material layer (120) may further include a binder. The binder may bind the positive active material, solid electrolyte, and conductive material within the positive active material layer (120) together. The binder may include a material to improve the bonding strength between the positive active material layer (120) and the positive current collector (110). The binder may include, for example, polyvinylidene fluoride, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate.

[0091] Based on 100 parts by weight of the total positive active material, solid electrolyte, conductive material, and binder, the positive active material layer (120) may contain 85 parts by weight or more and 92 parts by weight or less of the positive active material. Based on 100 parts by weight of the total positive active material, solid electrolyte, conductive material, and binder, the positive active material layer (120) may contain 0.5 parts by weight or more and 1.5 parts by weight or less of the binder.

[0092] Based on 100 parts by weight of solid electrolyte, the positive active material layer (120) may contain 1 part by weight or more and 50 parts by weight or less of a conductive material. If the conductive material is included in the positive active material layer (120) in an amount less than 1 part by weight based on 100 parts by weight of solid electrolyte, the proportion of the conductive material decreases, and the electrical conductivity of the positive active material layer (120) may decrease. If the conductive material is included in the positive active material layer (120) in an amount exceeding 50 parts by weight based on 100 parts by weight of solid electrolyte, the proportion of the conductive material is excessively high, and a coating layer covering the surface of the solid electrolyte may not be properly formed.

[0093] The positive active material layer (120) may further include additives such as fillers, coating agents, dispersants, and ion conductivity aids in addition to the positive active material, solid electrolyte, conductive material, and binder described above.

[0094] Referring to FIG. 1, a solid electrolyte layer (300) may be disposed between an anode layer (100) and a cathode layer (200). The solid electrolyte layer (300) may include a sulfide-based solid electrolyte with excellent lithium ion conductivity characteristics. The sulfide-based solid electrolyte may be Li3PO4-Li2SO4, Li2S-P2S5, Li2S-P2S5-LiX, where X is a halogen element, 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-P2S5-Z m S n , m, n are positive numbers, Z is one of Ge, Zn, or Ga, Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q , p, q are positive numbers, M is one of P, Si, Ge, B, Al, Ga, In, Li 7-x PS 6-x Cl x , 0≤x≤2, Li 7-x PS 6-x Br x , 0≤x≤2, and Li 7-x PS 6-x I x It may include one or more selected from 0≤x≤2. Since the description regarding the solid electrolyte in the solid electrolyte layer (300) described above can be applied as is to the solid electrolyte in the positive active material layer (120), a detailed description below will be omitted.

[0095] FIG. 9 is intended to illustrate a lithium metal battery (1000) according to another embodiment. Referring to FIG. 9, the lithium metal battery (1000) according to one embodiment may further include a lithium metal layer (230) disposed between a negative electrode current collector (210) and a solid electrolyte layer (300) by charging. The all-solid-state battery (1000) according to one embodiment may further include a lithium metal layer (230) disposed between a negative electrode current collector (210) and a negative electrode protection layer (220) by charging. Although not shown in the drawings, the all-solid-state battery (1000) may further include a lithium metal layer (230) disposed between a solid electrolyte layer (300) and a negative electrode protection layer (220) by charging. Since the description of each component included in the lithium metal battery (1000) can be applied as described above, a detailed description below will be omitted.

[0096] [Method for manufacturing a negative electrode for a lithium metal battery]

[0097] A method for manufacturing a negative electrode for a lithium metal battery according to another embodiment comprises: providing a negative electrode current collector or providing a laminate having a lithium metal layer disposed on the negative electrode current collector; and providing a negative electrode protective layer on the negative electrode current collector or on the lithium metal layer, wherein the negative electrode protective layer may comprise a polymer matrix and lithium-affinity metal particles dispersed within the polymer matrix. A lithium metal battery comprising a negative electrode manufactured by this method provides improved cycle characteristics.

[0098] First, a negative electrode current collector is provided. Refer to the above description regarding the negative electrode current collector. For example, copper foil may be provided as the negative electrode current collector. Alternatively, a laminate having a lithium metal layer disposed on the negative electrode current collector is provided. The method of disposing of the lithium metal layer on the negative electrode current collector is not particularly limited. For example, the lithium metal layer may be disposed on a metal substrate by sputtering, etc. Alternatively, for example, a copper foil / lithium foil laminate may be prepared by disposing of lithium foil on a metal substrate and rolling. Alternatively, a laminate having a lithium metal layer disposed on a copper foil may be commercially obtained and used. Alternatively, a laminate may be prepared by coating and drying a composition containing lithium powder and a binder on a metal substrate. Refer to the above description regarding the lithium powder and the binder.

[0099] Next, a cathode protective layer may be provided on the cathode current collector or on the lithium metal layer. The cathode protective layer may be provided, for example, by preparing a slurry by mixing lithium-affinity metal particles and a polymer material with a solvent, and then coating and drying the slurry on a metal substrate or a lithium metal layer.

[0100] The method of mixing lithium-affinity metal particles and polymer materials is not particularly limited. For example, lithium-affinity metal particles and a precursor material of the polymer matrix can be mixed in a solvent at once. As another example, lithium-affinity metal particles can be dispersed in a solvent, a precursor material of the polymer matrix can be dissolved in a solvent, and then the respective solvents can be mixed. When dispersing the lithium-affinity metal particles in a solvent, for example, ultrasonic dispersion may be used, but is not necessarily limited thereto. Refer to the above description for the lithium-affinity metal particles and the polymer matrix.

[0101] The coating method is not particularly limited and can be applied using a doctor blade, etc. The slurry may include, for example, lithium-affinity metal particles, a precursor material of a polymer matrix, a binder, and a solvent. The slurry may further include a metal oxide. The slurry may further include a carbon-based material. Refer to the above description regarding the metal oxide, carbon-based material, and binder. The solvent may be an organic solvent. The solvent may be, for example, NMP, but is not necessarily limited to these, and any solvent used in the relevant technical field is acceptable.

[0102] The drying method is not particularly limited and can be dried using a vacuum oven, etc. The cathode coated with the slurry can be placed in a vacuum oven and a heat treatment process at 100°C to 150°C can be performed. The heat treatment process can be carried out until the solvent of the slurry is completely dried.

[0103] The creative idea is explained in more detail through the following examples and comparative examples. However, the examples are intended to illustrate the creative idea and do not limit the scope of the creative idea to these examples alone.

[0104]

[0105] Example 1: Cu current collector / Li metal / PVDF-HFP matrix + Ag nanoparticle protective layer cathode

[0106] (Manufacturing of the cathode layer)

[0107] Ag powder with an average particle size (D50) of 30 nm was added to a solvent (NMP) and ultrasonically dispersed, and then a PVDF-HFP dispersion (10 wt% in NMP) was mixed to prepare a mixed solution. The mixed solution was mixed using a roller mixer at 100 rpm for 24 hours to prepare a dispersion (PVDF-HFP + Ag nanoparticles in NMP) slurry. The slurry was coated onto a copper thin film placed on a copper current collector using a doctor blade, and the cathode was prepared by drying in a vacuum oven at 80 ℃. The cathode had a structure in which a cathode protective layer with a thickness of 10 μm was coated on the copper current collector.

[0108] (Manufacturing of the anode layer)

[0109] LiCoO2 powder and carbon conductive material (Super-P; Timcal Ltd.) were uniformly mixed in a weight ratio of 90:5, and then a PVDF (polyvinylidenefluoride) binder solution was added to prepare an anode active material slurry with a weight ratio of active material:carbon-based conductive material:binder = 90:5:5.

[0110] The manufactured slurry was coated onto an aluminum substrate with a thickness of 15 μm using a doctor blade, dried under reduced pressure at 120°C, and then rolled into a sheet shape using a roll press to manufacture an anode.

[0111] (Battery manufacturing)

[0112] A simplified evaluation cell was manufactured using a carbonate electrolyte by attaching tabs to the manufactured anode and cathode.

[0113]

[0114] Example 2: Cu current collector / Li metal / PVDF matrix + Ag nanoparticle protective layer cathode

[0115] A cell was manufactured in the same manner as in Example 1, except that a mixed solution was prepared by mixing a PVDF dispersion (10 wt% in NMP) when manufacturing the cathode layer.

[0116]

[0117] Comparative Example 1: Cu current collector / Li metal cathode

[0118] A cell was manufactured in the same manner as in Example 1, except that it was laminated without a cathode protection layer.

[0119]

[0120] Comparative Example 2: Cu current collector / Li / metal / PVDF-HFP matrix protective layer cathode

[0121] A cell was prepared in the same manner as in Example 1, except that the cathode protective layer did not contain Ag nanoparticles.

[0122]

[0123] Evaluation: Charge / Discharge Test

[0124] The lithium metal batteries prepared in Examples 1 and 2 and Comparative Examples 1 and 2 were charged at a constant current rate of 0.1 C at 25 ℃ until the voltage reached 4.3 V, and then cut off at a current rate of 0.05 C while maintaining 4.3 V in constant voltage mode. Subsequently, they were discharged at a constant current rate of 0.1 C until the voltage reached 3.0 V during discharge (formation cycle).

[0125] A lithium metal battery that had undergone a formation cycle was charged at 25°C at a current rate of 0.3 C until the voltage reached 4.3 V, and then cut off at a current rate of 0.05 C while maintaining 4.3 V in constant voltage mode. Subsequently, it was discharged at a constant current rate of 0.3 C until the voltage reached 3.0 V during discharge (1 st Cycle). 70 of these cycles th The cycle was repeated under the same conditions.

[0126] In all charge / discharge cycles, a 10-minute pause was observed after each charge / discharge cycle. Some of the results of the room temperature charge / discharge experiments are shown in Table 1 and Figure 10 below. The capacity retention rate is defined by the following Equation 1.

[0127] <Mathematical Formula 1>

[0128] Capacity retention rate (retention, %) = [70 th Discharge capacity per cycle / 1 st [Discharge capacity per cycle] × 100(%)

[0129]

[0130] Protective layer composition capacity retention rate (@70 cycles, %) Example 1 PVDF-HFP + Ag nanoparticles 95 Example 2 PVDF + Ag nanoparticles 93 Comparative Example 1 None 88 Comparative Example 2 PVDF-HFP 89

[0131] As shown in Table 1 and Figure 10, the lithium metal batteries of Examples 1 and 2 showed improved capacity retention compared to the lithium metal battery of Comparative Example 1, which did not include a protective layer. This improved capacity retention was determined to be due to the fact that the formation of lithium dendrites was suppressed and the lithium metal layer was protected, thereby effectively preventing the degradation of the lithium metal layer. As shown in Table 1 and Figure 10, the lithium metal batteries of Examples 1 and 2 showed improved capacity retention compared to the lithium metal battery of Comparative Example 2, which included a protective layer. This improved capacity retention was determined to be due to the fact that Ag nanoparticles within the protective layer improved the lithium ion conductivity within the protective layer, thereby preventing the protective layer from acting as a resistive layer.

[0132] Although an exemplary embodiment has been described in detail above with reference to the attached drawings, the present creative idea is not limited to such examples. It is obvious that a person skilled in the art to which the present creative idea belongs can derive various variations or modifications within the scope of the technical idea described in the patent claims, and these also naturally fall within the technical scope of the present creative idea.

Claims

cathode current collector; and It includes a cathode protective layer on the above-mentioned cathode current collector; The above-described negative electrode protective layer comprises a polymer matrix and lithium-affinity metal particles dispersed within the polymer matrix, for a negative electrode for a lithium metal battery. In paragraph 1, The lithium-affinity metal particles described above comprise aluminum (Al), silver (Ag), copper (Cu), gold (Au), titanium (Ti), nickel (Ni), cobalt (Co), iron (Fe), manganese (Mn), magnesium (Mg), potassium (K), chromium (Cr), tin (Sn), vernadium (V), zinc (Zn), or a combination thereof, for a negative electrode for a lithium metal battery. In paragraph 1, The above lithium-affinity metal particles comprise silver (Ag), nickel (Ni), cobalt (Co), iron (Fe), zinc (Zn), or a combination thereof, for a negative electrode for a lithium metal battery. In paragraph 1, A negative electrode for a lithium metal battery, wherein the average particle size of the lithium-affinity metal particles is 5 nm to 900 nm. In paragraph 1, A negative electrode for a lithium metal battery, wherein the negative electrode protective layer comprises 10 to 40 parts by weight of the lithium-affinity metal particles per 100 parts by weight of the polymer matrix. In paragraph 1, The above polymer matrix is ​​carboxymethylcellulose (CMC), polyethylene glycol (PEG), polyethylene oxide (PEO), polyethylene glycol methacrylate (PEGMA), polyethylene glycol dimethacrylate (PEGDMA), polyethylene carbonate (PEC), polytrimethylene carbonate (PTMC), polypropylene carbonate (PPC), polyvinylidene fluoride (PVDF), polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP), polyacrylonitrile (PAN), A negative electrode for a lithium metal battery comprising polyacrylic acid (PAA) or a combination thereof. In paragraph 1, The above polymer matrix comprises poly(ethylene oxide, PEO), poly(vinylidene fluoride, PVDF), poly(vinylidene fluoride-co-hexafluoropropylene, PVDF-HFP), polyacrylonitrile (PAN), polyacrylic acid (PAA), or a combination thereof, for a negative electrode for a lithium metal battery. In paragraph 1, A negative electrode for a lithium metal battery, wherein the thickness of the negative electrode protective layer is 0.1 to 30 μm. In paragraph 1, The above cathode protective layer further includes a binder, The above binder is polytetrafluoroethylene (PTFE), polyamide-imide (PAI), polyimide (PI), styrene-butadiene rubber (SBR), (meth)acrylated styrene-butadiene rubber, polyethylene oxide (PEO), polyphosphazene, poly(meth)acrylonitrile (PAN), (meth)acrylic resin, phenol resin, epoxy resin, polyvinyl alcohol (PVA), polyvinylidene fluoride (PVDF), and polyvinylidene A negative electrode for a lithium metal battery comprising a polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP) or a combination thereof. In paragraph 1, The above-mentioned cathode current collector further includes a carbon layer disposed on one or both sides, and The above carbon layer comprises amorphous carbon, crystalline carbon, or a combination thereof, for a negative electrode of a lithium metal battery. In Paragraph 10, A negative electrode for a lithium metal battery, wherein the thickness of the carbon layer is 1 μm to 5 μm. In paragraph 1, The above-described negative electrode protective layer extends to at least one side of the above-described negative electrode current collector, for a negative electrode of a lithium metal battery. In paragraph 1, It further includes a lithium metal layer disposed between the above-mentioned negative electrode current collector and the above-mentioned negative electrode protective layer, and The above lithium metal layer comprises lithium or a lithium alloy, and is a negative electrode for a lithium metal battery. In Paragraph 13, The above lithium alloy comprises a Li-Al alloy, a Li-Sn alloy, a Li-In alloy, a Li-Ag alloy, a Li-Au alloy, a Li-Zn alloy, a Li-Ge alloy, a Li-Si alloy, or a combination thereof, for a negative electrode for a lithium metal battery. A positive layer comprising a positive current collector and a positive active material layer on the positive current collector; cathode layer; and It includes an electrolyte layer disposed between the anode layer and the cathode layer; A lithium metal battery comprising the negative electrode of claim 1, wherein the above negative electrode layer comprises the negative electrode. In paragraph 15, A lithium metal battery in which the region between the negative current collector and the negative protection layer is a Li-free region that does not contain lithium (Li). In paragraph 15, It further includes a lithium metal layer disposed between the above-mentioned negative electrode current collector and the above-mentioned negative electrode protective layer, and The above lithium metal layer comprises lithium or a lithium alloy, and A lithium metal battery comprising the above lithium alloy, a Li-Al alloy, a Li-Sn alloy, a Li-In alloy, a Li-Ag alloy, a Li-Au alloy, a Li-Zn alloy, a Li-Ge alloy, a Li-Si alloy, or a combination thereof. In paragraph 15, A lithium metal battery comprising a positive electrode active material layer comprising lithium transition metal oxides such as lithium cobalt oxide (LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium manganate, and lithium iron phosphate, nickel sulfide, copper sulfide, lithium sulfide, iron oxide, or vanadium oxide, or a combination thereof. In paragraph 15, The above electrolyte layer comprises a liquid electrolyte, a solid electrolyte, or a combination thereof in a lithium metal battery. In paragraph 15, The above electrolyte layer includes a solid electrolyte, and The above solid electrolyte includes a sulfide-based solid electrolyte, and The above sulfide-based solid electrolyte is Li3PO4-Li2SO4, Li2S-P2S5, Li2S-P2S5-LiX, where X is a halogen element, 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-P2S5-Z m S n , m, n are positive numbers, Z is one of Ge, Zn, or Ga, Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q , p, q are positive numbers, M is one of P, Si, Ge, B, Al, Ga, In, Li 7-x PS 6-x Cl x , 0≤x≤2, Li 7-x PS 6-x Br x , 0≤x≤2, and Li 7-x PS 6-x I x A lithium metal battery comprising one or more selected from , 0≤x≤2.

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