Cathode active material composite, cathode and secondary battery including same

Abstract

The present invention relates to a cathode active material composite comprising: a cathode active material; and a coating layer included on at least a portion of the surface of the cathode active material, wherein the coating layer comprises a Br-containing sulfide solid electrolyte and an oxide.

Description

Cathode active material composite, cathode, and secondary battery including the same

[0001] The present invention relates to a positive electrode active material composite, a positive electrode, and a secondary battery comprising the same.

[0002] Recently, accompanied by the rapid proliferation of battery-powered electronic devices such as mobile phones, laptops, computers, and electric vehicles, the demand for small, lightweight, and relatively high-capacity rechargeable batteries is rapidly increasing. In particular, lithium-ion batteries are gaining attention as power sources for portable devices due to their lightweight design and high energy density. Accordingly, active research and development efforts are underway to improve the performance of lithium-ion batteries.

[0003] A battery in which the liquid electrolyte used in conventional secondary batteries is replaced with a solid electrolyte is called an all-solid-state battery. All-solid-state batteries have the advantage of significantly improving safety because they do not use flammable solvents, so there is absolutely no risk of ignition or explosion caused by decomposition reactions of conventional electrolytes.

[0004] In these all-solid-state batteries, lithium ion conduction occurs at the interface through a solid electrolyte in powder form. Therefore, it is necessary to maximize lithium ion conduction between particles within the all-solid-state battery and prevent contact loss between particles caused by volume changes during charging and discharging.

[0005] To this end, methods such as applying pressure using jigs, utilizing isotropic pressure, and modifying electrode materials have been studied; however, there are still limitations in improving battery performance by enhancing lithium ion transfer.

[0006] The present invention is designed to solve the above problems and aims to provide a positive electrode active material composite in which the electron and / or ion conductivity of the positive electrode, which is one of the components of a secondary battery, is improved, or the interfacial side reaction between the positive electrode active material and the solid electrolyte is suppressed.

[0007] By providing a cathode containing such a cathode active material composite and using it in a secondary battery, the electron and / or ion conductivity between the cathode and the solid electrolyte layer is improved, thereby suppressing side reactions at the interface between the cathode and the solid electrolyte layer and providing a secondary battery with excellent rate characteristics and / or life characteristics.

[0008] The present invention provides a positive electrode active material composite comprising: a positive electrode active material; and a coating layer provided on at least a portion of the surface of the positive electrode active material; wherein the coating layer comprises a Br-containing sulfide solid electrolyte and an oxide.

[0009] In one embodiment, the oxide may include an oxide comprising one or more selected from lithium (Li), niobium (Nb), zirconium (Zr), tungsten (W), boron (B), and titanium (Ti).

[0010] In one embodiment, the oxide is lithium niobate, lithium titanate, lithium zirconium oxide, lithium tungsten oxide, lithium borate, crystalline oxide, amorphous oxide, lithium oxide, titanium dioxide (TiO₂). b , 0 <b<5), 지르코늄 옥사이드, 텅스텐 옥사이드, 보론 옥사이드 및 이들의 혼합물로 이루어진 군에서 선택되는 하나 이상을 포함할 수 있다.

[0011] In one embodiment, the Br-containing sulfide solid electrolyte may include a Br-containing sulfide solid electrolyte represented by the following chemical formula 1.

[0012] [Chemical Formula 1]

[0013] Li a PS b X c Br d

[0014] In the above chemical formula 1, X is at least one selected from F, Cl, and I, and 5≤a≤6, 4≤b≤5, 0 <c≤1, 0<d≤1 이다.

[0015] In one embodiment, the coating layer may be amorphous.

[0016] In one embodiment, the coating layer comprises a first layer provided on at least a portion of the surface of the positive active material; and a second layer provided on at least a portion of the surface of the positive active material or the surface of the first layer, wherein the first layer comprises the oxide and the second layer may comprise the Br-containing sulfide solid electrolyte.

[0017] In one embodiment, the Br-containing sulfide solid electrolyte may be included in an amount of 0.1 parts by weight or more to 5 parts by weight or less based on 100 parts by weight of the positive electrode active material.

[0018] In one embodiment, the average particle size (D) of the Br-containing sulfide solid electrolyte 50 The average particle size (D) of the above positive active material relative to ) 50 The ratio of ) may be 1.3 or more to 1000 or less.

[0019] In one embodiment, the average particle size (D) of the Br-containing sulfide solid electrolyte 50 ) may be 0.01 μm or more to 1.5 μm or less.

[0020] In one embodiment, the average particle size (D of the positive active material) of the positive active material 50 ) may be 2 μm or more to 10 μm or less.

[0021] In one embodiment, the thickness of the first layer may be 1 nm or more to 100 nm or less, and the thickness of the second layer may be 10 nm or more to 10 μm or less.

[0022] The present invention provides an anode comprising the above-mentioned anode active material composite; a solid electrolyte; a conductive material; and a binder.

[0023] In addition, the present invention provides a secondary battery comprising the above positive electrode.

[0024] The cathode active material composite according to the present invention has the effect of suppressing side reactions at the interface between the cathode active material and the solid electrolyte by including a coating layer comprising an oxide and a Br-containing sulfide solid electrolyte on the surface of the cathode active material.

[0025] Furthermore, the electron and / or ion conductivity within the anode can be improved, and accordingly, a secondary battery with improved lifespan and / or electrochemical performance can be provided.

[0026] In addition, when using the positive active material composite of the present invention, even when manufacturing the electrode using a dry process method, the high power performance or lifespan characteristics are improved as the ion conductivity is enhanced.

[0027] Figure 1 is a graph showing the voltage curve according to the capacity during charging and discharging of the all-solid-state battery of Example 1 according to Experimental Example 1.

[0028] Figure 2 is a graph showing the voltage curve according to the capacity during charging and discharging of the all-solid-state battery of Example 2 according to Experimental Example 1.

[0029] Figure 3 is a graph showing the voltage curve according to the capacity during charging and discharging of the all-solid-state battery of Example 3 according to Experimental Example 1.

[0030] Figure 4 is a graph showing the voltage curve according to the capacity during charging and discharging of the all-solid-state battery of Comparative Example 1 according to Experimental Example 1.

[0031] Figure 5 is a graph showing the voltage curve according to the capacity during charging and discharging of the all-solid-state battery of Comparative Example 2 according to Experimental Example 1.

[0032] Figure 6 is a graph showing the voltage curve according to the charge / discharge capacity of the all-solid-state battery of Comparative Example 3 according to Experimental Example 1.

[0033] Figure 7 is a graph showing the voltage curve according to the capacity during charging and discharging of the all-solid-state battery of Comparative Example 4 according to Experimental Example 1.

[0034] Figure 8 is a graph showing the rate capability performance characteristics of the all-solid-state battery of Example 1 according to Experimental Example 1.

[0035] Figure 9 is a graph showing the rate capability performance characteristics of the all-solid-state battery of Example 2 according to Experimental Example 1.

[0036] Figure 10 is a graph showing the rate capability performance characteristics of the all-solid-state battery of Example 3 according to Experimental Example 1.

[0037] Figure 11 is a graph showing the rate capability performance characteristics of the all-solid-state battery of Comparative Example 1 according to Experimental Example 1.

[0038] Figure 12 is a graph showing the rate capability performance characteristics of Comparative Example 2 according to Experimental Example 1.

[0039] Figure 13 is a graph showing the rate capability performance characteristics of the all-solid-state battery of Comparative Example 3 according to Experimental Example 1.

[0040] Figure 14 is a graph showing the rate capability performance characteristics of the all-solid-state battery of Comparative Example 4 according to Experimental Example 1.

[0041] Figure 15 shows the results of evaluating the coating layer thickness by SEM / EDS line scanning analysis of the positive electrode active material composite of Example 2 according to Experimental Example 2.

[0042] Figure 16 shows the results of evaluating the coating layer area of ​​the cathode active material composite of Example 2 according to Experimental Example 3 using SEM / EDS and an image program.

[0043] Figure 17 is a figure showing the results of XPS analysis of the positive active material composite of Example 2 according to Experimental Example 4.

[0044] Figure 18 shows the results of XRD analysis of the positive active material composite of Example 2 according to Experimental Example 5.

[0045] Figure 19 is a graph showing the results of evaluating the rate capability performance characteristics according to Experimental Example 6.

[0046] Terms and words used in this specification and claims shall not be interpreted as being limited to their ordinary or dictionary meanings, but shall be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0047] Therefore, the configurations of the embodiments described in this specification are merely one of the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention; thus, it should be understood that various equivalents and modifications capable of replacing them may exist at the time of filing this application. In this specification, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0048] In this specification, when a part is described as “comprising” a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. Thus, for example, a composition comprising compound A may include compounds other than A. However, the term “comprising” also encompasses, in a more restrictive sense as a specific embodiment thereof, “essentially / essentially composed of” and “composed of,” so, for example, a “composition comprising compound A” may also be (essentially / essentially) composed of compound A.

[0049] In connection with this, terms such as “comprising” or “having,” as described in this specification, are intended to specify the existence of the implemented features, numbers, steps, components, or combinations thereof, and should not be understood as precluding the existence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0050] In the present specification, when it is stated that any layer is located or provided “on” or “between” another arbitrary layer, this includes not only cases where any layer is in contact with another arbitrary layer, but also cases where another layer or material, etc. exists between the two layers.

[0051] Where in this specification a quantity, concentration, or other value or parameter is given as an enumeration of a range, a preferred range, a preferred upper limit, and a preferred lower limit, it should be understood that any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether the range is disclosed separately, specifically discloses all ranges that may be formed. Where a range of numerical values ​​is mentioned in this specification, unless otherwise stated, for example, without limiting terms such as greater than or less than, the range is intended to include its endpoint value and all integers and fractions within that range. The scope of the invention is not intended to be limited to the specific value mentioned when defining the range.

[0052] Among the physical properties mentioned in this specification, if the measured temperature affects the property, the property is measured at room temperature unless specifically otherwise specified. The term "room temperature" refers to a natural temperature that has not been heated or cooled, and may mean, for example, any temperature within the range of about 10°C to 30°C, about 23°C, or about 25°C. Furthermore, unless specifically otherwise specified, the unit of temperature in this specification is °C.

[0053] In addition, among the physical properties mentioned in this specification, if the measured pressure affects the physical property, unless otherwise specifically defined, the physical property is measured at normal pressure, that is, atmospheric pressure (about 1 atmosphere).

[0054] In this specification, “average particle size (D 50")" refers to the particle size at the 50% reference of the volume-cumulative particle size distribution of the particles, and can be measured using the laser diffraction method. For example, after dispersing the powder to be measured in a dispersion medium, or after introducing the powder to be measured in a dry state into a measurement unit under vacuum, it can be measured by introducing it into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000), irradiating it with ultrasound of about 28 kHz at an output of 60 W, obtaining a volume-cumulative particle size distribution graph, and then determining the particle size corresponding to 50% of the volume-cumulative amount.

[0055] One embodiment of the present invention provides a positive electrode active material composite. The positive electrode active material composite comprises a positive electrode active material; and a coating layer provided on at least a portion of the surface of the positive electrode active material; wherein the coating layer may include a Br-containing sulfide solid electrolyte and an oxide.

[0056] The cathode active material composite according to the present invention can increase ion conductivity by improving interfacial contact between the cathode active material composite and the solid electrolyte, while also having the effect of suppressing side reactions occurring at the interface between the cathode active material and the solid electrolyte. When manufacturing an electrode with high loading, such performance improvement is required, and accordingly, the cathode active material composite of the present invention includes a coating layer on the surface of the cathode active material, and the Br-containing sulfide solid electrolyte and oxide included in the coating layer each perform the same or different functions or roles, thereby improving such performance.

[0057] The above-mentioned positive electrode active material is a material that serves as a source of lithium ions during charging and discharging, and includes a material capable of absorbing and releasing lithium ions. The above-mentioned positive electrode active material is a layered compound such as lithium cobalt oxide (LiCoO2) or lithium nickel oxide (LiNiO2), or a material with the chemical formula Li (1-b) (Ni x M1 (1-x) )M 2 y O2(here M 1 is at least one selected from Co and Mn, and M 2 is at least one selected from Al, Zr, B, W, Mo, Cr, Ta, Nb, Mg, Ce, Hf, La, Ti, Sr, Ba, F, P, S, Na, Si, and Y, and 0 <b<0.1, 0.3≤x≤1, 0≤y≤0.1)의 층상구조 화합물; LiFe3O4등의 리튬 철 산화물; 화학식 Li 1+c1 Mn 2-c1 Lithium manganese oxides such as O4 (0≤c1≤0.33), LiMnO3, LiMn2O3, LiMnO2, etc.; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, Cu2V2O7, etc.; chemical formula LiNi 1-c2 M c2 Ni-site type lithium nickel oxide represented by O2 (wherein M is at least one selected from the group consisting of Co, Mn, Al, Cu, Fe, Mg, B, and Ga, satisfying 0.01≤c2≤0.3); chemical formula LiMn 2-c3 M c3 A lithium manganese complex oxide represented by O2 (wherein M is at least one selected from the group consisting of Co, Ni, Fe, Cr, Zn, and Ta, satisfying 0.01 ≤ c3 ≤ 0.1) or Li2Mn3MO8 (wherein M is at least one selected from the group consisting of Fe, Co, Ni, Cu, and Zn); LiMn2O4 in which part of the Li in the chemical formula is substituted with an alkaline earth metal ion; a lithium iron phosphate compound (LFP) having the chemical formula LiFePO4, for example; LiFe x M1 (1-x) P y M2 (1-y)O4(wherein, M1 = 1 or more of Mn, Co, Ni, Al, V, B, Cd, Cu, Mg, Zn, Ti, Nb, Zr and Cr, and 0 <x≤1, M2 = Si, N, S, Cl, Br, 및 F 중 1 이상이며, 0<y≤1)의 화학식을 갖는 리튬 철 금속 인산화물(LMFP); 등을 들 수 있지만, 이들만으로 한정되는 것은 아니다.

[0058] The above positive active material may have a capacity per weight of 160 mAh / g or more. Specifically, it may be 165 mAh / g or more, 170 mAh / g or more, 175 mAh / g or more, or 180 mAh / g or more. In addition, the redox potential of the above positive active material may be 4.5 V or less.

[0059] The above positive active material may preferably include a compound with a layered structure, but is not limited thereto.

[0060] The above positive active material particles may be primary particles, secondary particles formed by the aggregation of primary particles, or single particles in the form of a single crystal, but are not limited thereto.

[0061] Average particle size (D) of the above positive active material 50 ) may be 2 μm or more to 10 μm or less, specifically 3 μm or more to 8 μm or less, but is not limited thereto.

[0062] The above-mentioned positive active material may be included in an amount of 60% by weight or more to 99% by weight or less based on the total weight of the above-mentioned positive active material composite. Specifically, the above-mentioned positive active material may be included in an amount of 60% by weight or more to 98.5% by weight or less, 65% by weight or more to 98% by weight or less, or 70% by weight or more to 95% by weight or less based on the total weight of the above-mentioned positive active material composite. When the content of the above-mentioned positive active material satisfies the above range, interfacial side reactions with the solid electrolyte of the above-mentioned positive active material composite can be suppressed, and the lifespan or performance of the secondary battery can be improved.

[0063] The above positive active material may have a coating layer provided on at least a portion of its surface. Specifically, a coating layer may be provided on at least a portion of the surface of the above positive active material particles.

[0064] The statement that a coating layer is provided on at least a portion of the surface of the positive active material may mean that the coating layer exists on the surface of the positive active material. For example, it may mean that the coating layer is coated on the surface of the positive active material, that the coating layer is coated on the surface of the positive active material, that the coating layer is film-formed on the surface of the positive active material, that the coating layer is applied to the surface of the positive active material, or that the coating layer is deposited on the surface of the positive active material, but is not limited thereto.

[0065] The meaning of the coating layer being provided on at least a portion of the surface of the positive active material is that the coating layer may be included in an area of ​​1% or more to 99% or less of the total area of ​​the positive active material, may be included in an area of ​​10% or more to 90% or less, may be included in an area of ​​20% or more to 80% or less, may be included in an area of ​​30% or more to 70% or less, may be included in an area of ​​50% or more to 60% or less, or may be included in an area of ​​5% or more to 70% or less, an area of ​​10% or more to 60% or less, an area of ​​10% or more to 50% or less, an area of ​​10% or more to 40% or less, or an area of ​​15% or more to 30% or less, but is not limited thereto.

[0066] When the above coating layer is included on the surface of the positive electrode active material while satisfying the above range, it has the effect of suppressing interfacial side reactions between the positive electrode active material and the solid electrolyte and improving ion conductivity.

[0067] The above coating layer may include a Br-containing sulfide solid electrolyte and an oxide.

[0068] The oxide may comprise an oxide comprising one or more selected from lithium (Li), niobium (Nb), zirconium (Zr), tungsten (W), boron (B), and titanium (Ti). The oxide may comprise at least one oxide comprising one or more selected from lithium (Li), niobium (Nb), zirconium (Zr), tungsten (W), boron (B), and titanium (Ti).

[0069] The oxide may be an oxide that does not contain phosphorus (P). For example, the oxide may not contain phosphorus (P), or the oxide may not contain an oxide that contains phosphorus (P).

[0070] For example, the oxide may include lithium oxide. For example, the oxide may include one or more selected from niobium, zirconium, tungsten, boron, and titanium, and lithium, but is not limited thereto.

[0071] The oxide may be a crystalline oxide, an amorphous oxide, or a mixture thereof. It is preferable that the oxide be amorphous, as this can suppress side reactions of the positive electrode active material and improve ion conductivity.

[0072] The above oxides are lithium niobate, lithium titanate, lithium zirconium oxide, lithium tungsten oxide, lithium borate, crystalline oxide, amorphous oxide, lithium oxide, titanium dioxide (TiO₂). b , 0 <b<5), 지르코늄 옥사이드, 텅스텐 옥사이드, 보론 옥사이드 및 이들의 혼합물로 이루어진 군에서 선택되는 적어도 하나를 포함할 수 있다. 상기 산화물은 1종의 산화물을 포함할 수도 있고, 2종 이상의 산화물을 포함할 수도 있으나, 이에 한정되는 것은 아니다.

[0073] In one example, the oxide is Li x Nb y O z (here, 0 <x≤3, 0<y≤3, 0<z≤6), Li x Zr y O z (here, 0 <x≤3, 0<y≤2, 0<z≤5), Li x Ti y O z (where, 1≤x≤6, 1≤y≤6, 3≤z≤15), Li x B y O z (here, 0 <x≤3, 0<y≤2, 0<z≤6), Li2O, TiO b (here, 0 <b<5), ZrO b (here, 0 <b<5), WO b (here, 0 <b<6), BOb (here, 0 <b<6), αTi x O y -βLi2O (where 6≤α+β≤8, 0.7≤Li / Ti≤0.9), Li x W y O z (here, 0 <x≤3, 0<y≤3, 0<z≤5), 또는 이들의 혼합물을 포함할 수 있다.

[0074] The oxide may be included in an amount of 0.1 parts by weight or more to 5 parts by weight or less based on 100 parts by weight of the positive electrode active material. For example, the oxide may be included in an amount of 0.1 parts by weight or more to 4.8 parts by weight or less, 0.1 parts by weight or more to 4.6 parts by weight or less, 0.15 parts by weight or more to 4.5 parts by weight or less, 0.2 parts by weight or more to 4 parts by weight or less, or 0.5 parts by weight or more to 3 parts by weight or less based on 100 parts by weight of the positive electrode active material. When the content of the oxide satisfies the above range, the positive electrode active material composite can suppress side reactions occurring at the interface with the solid electrolyte, or can improve the lithium ion transfer ability between the positive electrode and the solid electrolyte layer.

[0075] The above Br-containing sulfide solid electrolyte may include a sulfide solid electrolyte that essentially contains the element Br. The above Br-containing sulfide solid electrolyte has softer properties than a sulfide solid electrolyte that does not contain the element Br, and can have a continuous interface with the positive electrode active material, which can result in excellent ion transport ability.

[0076] The above Br-containing sulfide solid electrolyte may include a sulfide solid electrolyte containing Br and Cl elements, and, for example, may include a sulfide-based solid electrolyte containing Br and Cl elements.

[0077] The above Br-containing sulfide solid electrolyte can be represented by the following chemical formula 1.

[0078] [Chemical Formula 1]

[0079] Li a PS b X c Br d In the above chemical formula 1, X is at least one selected from F, Cl, and I, and 5≤a≤6, 4≤b≤5, 0 <c≤1, 0<d≤1 이다.

[0080] The above X can be Cl.

[0081] The above Br-containing sulfide solid electrolyte may be crystalline or amorphous, and the above Br-containing sulfide solid electrolyte may include both crystalline and amorphous forms.

[0082] For example, the Br-containing sulfide solid electrolyte may be amorphous. When the Br-containing sulfide solid electrolyte is amorphous, it facilitates the effective formation of an interface between the Br-containing sulfide solid electrolyte and the solid electrolyte within the anode or the solid electrolyte layer at the surface of the anode active material, which is desirable in terms of ion conductivity.

[0083] The above Br-containing sulfide solid electrolyte may not detect diffraction peaks at positions 2θ=24.5° to 26°, 29° to 31°, and 30° to 32° during XRD measurement. Diffraction peaks detected at positions 2θ=24.5° to 26°, 29° to 31°, and 30° to 32° during XRD measurement may be the result of analysis of a crystalline sulfide-based solid electrolyte. The fact that the above Br-containing sulfide solid electrolyte does not detect diffraction peaks at positions 2θ=24.5° to 26°, 29° to 31°, and 30° to 32° during XRD measurement may mean that the above Br-containing sulfide solid electrolyte is amorphous. As described above, when the Br-containing sulfide solid electrolyte is amorphous, the interfacial bonding at the surface of the positive electrode active material can be improved, so the rate characteristics and life characteristics of the all-solid-state battery containing the positive electrode active material composite can be improved.

[0084] The Br-containing sulfide solid electrolyte may be included in an amount of 0.1 parts by weight or more to 5 parts by weight or less based on 100 parts by weight of the positive electrode active material. The Br-containing sulfide solid electrolyte may be included in an amount of 0.1 parts by weight or more to 4.8 parts by weight or less, 0.1 parts by weight or more to 4.6 parts by weight or less, 0.15 parts by weight or more to 4.5 parts by weight or less, 0.2 parts by weight or more to 4 parts by weight or less, or 0.5 parts by weight or more to 3 parts by weight or less based on 100 parts by weight of the positive electrode active material. When the content of the Br-containing sulfide solid electrolyte satisfies the above range, the positive electrode active material composite can suppress side reactions occurring at the interface with the solid electrolyte, or can improve the lithium ion transfer ability between the positive electrode and the solid electrolyte layer.

[0085] Average particle size (D) of the above Br-containing sulfide solid electrolyte 50) may be 0.01 μm or more to 1.5 μm or less, specifically 0.01 μm or more to 1 μm or less, or 0.02 μm or more to 0.9 μm or less, but is not limited thereto.

[0086] Average particle size (D) of the above Br-containing sulfide solid electrolyte 50 The average particle size (D) of the above positive active material relative to ) 50 The ratio of ) may be 1.3 or more to 1000 or less. For example, the average particle size (D) of the Br-containing sulfide solid electrolyte above 50 The average particle size (D) of the above positive active material relative to ) 50 The ratio of ) may be 3 or more to 40 or less. The average particle size (D) of the Br-containing sulfide solid electrolyte and the cathode active material. 50 When the ratio of ) satisfies the above range, the adhesion between the anode active material composite and the particles within the anode is improved, and accordingly, the ion and / or electronic conductivity is improved.

[0087] The coating layer comprises a first layer provided on at least a portion of the surface of the positive active material; and a second layer provided on at least a portion of the surface of the positive active material or the first layer, wherein the first layer may include the oxide and the second layer may include the Br-containing sulfide solid electrolyte.

[0088] The first layer is provided on at least a portion of the surface of the positive active material, and the first layer may cover at least a portion of the surface of the positive active material. The meaning of the first layer being provided on at least a portion of the surface of the positive active material may mean that the first layer exists on the surface of the positive active material. For example, it may mean that the first layer is coated on the surface of the positive active material, or that the first layer is film-formed on the surface of the positive active material, or that the first layer is applied or deposited on the surface of the positive active material, but is not limited thereto.

[0089] If the first layer contains an oxide, the positive active material can play a role in suppressing side reactions occurring at the interface with the solid electrolyte.

[0090] At this time, the first layer may mean that it is provided on at least a part of the surface of the positive active material and forms a continuous surface, or that the component of the first layer is provided on at least a part of the surface of the positive active material while forming a discontinuous surface such as an island shape, or that it may include both of the above cases.

[0091] In cases where the first layer is provided on at least a portion of the surface of the positive active material while forming a discontinuous surface such as an island shape, the first layer may be a concept that includes all parts formed by a virtual surface connecting the outermost points of the components of the first layer provided on the surface of the positive active material.

[0092] The first layer above may be included in an area of ​​1% or more to 99% or less of the total surface area of ​​the positive electrode active material, may be included in an area of ​​10% or more to 99% or less, may be included in an area of ​​20% or more to 90% or less, may be included in an area of ​​30% or more to 80% or less, or may be included in an area of ​​50% or more to 70% or less, or may be included in an area of ​​1% or more to 90% or less, an area of ​​10% or more to 90% or less, an area of ​​20% or more to 80% or less, an area of ​​40% or more to 70% or less, or an area of ​​50% or more to 60% or less, but is not limited thereto.

[0093] When the above first layer is provided on the surface of the positive electrode active material while satisfying the above range, it has the effect of suppressing interfacial side reactions between the positive electrode active material and the solid electrolyte.

[0094] The second layer may be provided on the surface of the positive active material or on at least a portion of the surface of the first layer. That is, the second layer may be provided on at least a portion of the surface of the positive active material or on at least a portion of the surface of the first layer. Alternatively, the second layer may be provided on at least a portion of the surface of the positive active material and at least a portion of the surface of the first layer.

[0095] As the second layer is provided on at least a portion of the surface of the positive active material or the surface of the first layer as described above, it can play a role in improving conductivity by enhancing ion and / or electron transfer of the positive active material complex within the positive electrode, or it can play a role in suppressing side reactions at the interface of the positive active material complex.

[0096] The meaning of the second layer being provided on at least a portion of the surface of the positive active material or the surface of the first layer may mean that the second layer exists on the surface of the positive active material or the surface of the first layer. For example, it may mean that the second layer is coated on the surface of the positive active material or the surface of the first layer, or that the second layer is coated on the surface of the positive active material or the surface of the first layer, or that the second layer is film-formed on the surface of the positive active material or the surface of the first layer, or that the second layer is applied or deposited on the surface of the positive active material or the surface of the first layer.

[0097] At this time, the second layer may mean that it is provided on at least a part of the surface of the positive active material or the surface of the first layer and forms a continuous surface, or that the components of the second layer may be provided on at least a part of the surface of the positive active material or the surface of the first layer while forming a discontinuous surface such as an island shape, or that it may include all of the above two cases.

[0098] In cases where the second layer is provided on at least a part of the surface of the positive active material or the surface of the first layer while forming a discontinuous surface such as an island shape, the second layer may be a concept that includes all parts formed by a virtual surface connecting the outermost points of the components of the second layer provided on the surface of the positive active material or the surface of the first layer.

[0099] When the second layer is provided on at least a portion of the positive active material, the first layer and the second layer may be provided on the surface of the positive active material. That is, a first region composed of the components of the first layer and a second region composed of the components of the second layer may be provided on the surface of the positive active material. In this case, the first region composed of the components of the first layer may be provided continuously or discontinuously, and the second region composed of the components of the second layer may be provided continuously or discontinuously.

[0100] When the second layer is provided on at least a portion of the surface of the first layer, a third region forming a plurality of layers may be provided on the surface of the positive active material.

[0101] The first layer above includes the oxide, and the same content regarding the oxide described above can be applied to the oxide.

[0102] The second layer above includes the Br-containing sulfide solid electrolyte, and the Br-containing sulfide solid electrolyte can be applied in the same way as the Br-containing sulfide solid electrolyte described above.

[0103] The second layer may be provided in an area of ​​1% or more to 99% or less of the total surface area of ​​the positive active material or the first layer, in an area of ​​10% or more to 99% or less, in an area of ​​20% or more to 90% or less, in an area of ​​30% or more to 90% or less, or in an area of ​​50% or more to 80% or less, or in an area of ​​5% or more to 70% or less, in an area of ​​10% or more to 60% or less, in an area of ​​1% or more to less than 50%, in an area of ​​10% or more to less than 50%, in an area of ​​15% or more to 40% or less, or in an area of ​​15% or more to 30% or less, but is not limited thereto.

[0104] The second layer may be provided in an area of ​​less than 50% of the total surface area of ​​the surface of the positive active material or the first layer. Alternatively, the second layer may be provided in an area of ​​1% or more to less than 50%, 5% or more to less than 50%, 10% or more to less than 50%, 10% or more to 40% or less, or 15% or more to 30% or less of the total surface area of ​​the surface of the positive active material or the first layer.

[0105] When the above second layer is included on the surface of the positive active material or the surface of the first layer while satisfying the above range, the electron and / or ion conductivity within the positive electrode can be improved.

[0106] The coating layer may be amorphous. For example, the coating layer may be essentially amorphous. The meaning of the coating layer being essentially amorphous is that the main component of the coating layer exists in an amorphous state. For example, it may mean that the main component of the coating layer is amorphous and contains crystalline components as impurities as the remaining components.

[0107] The coating layer may not detect diffraction peaks at positions 2θ = 24.5° to 26°, 29° to 31°, and 30° to 32° during XRD measurement. The fact that the coating layer does not detect diffraction peaks at positions 2θ = 24.5° to 26°, 29° to 31°, and 30° to 32° during XRD measurement may mean that the coating layer is amorphous.

[0108] One or more of the first and second layers provided in the coating layer may be amorphous. Both the first and second layers provided in the coating layer may be amorphous.

[0109] In one example, one or more of the first layer and the second layer may be essentially amorphous. The meaning of one or more of the first layer and the second layer being essentially amorphous is that the main component of the first layer is amorphous, or the main component of the second layer is amorphous. Alternatively, it may mean that both the main component of the first layer and the main component of the second layer are amorphous. That is, it may mean that the components forming the first layer and the second layer contain amorphous components as the main components, and the remainder contain crystalline components as impurities. For example, the first layer may contain an amorphous oxide, and the second layer may contain an amorphous Br-containing sulfide solid electrolyte.

[0110] If one or more of the first and second layers included in the coating layer are amorphous, the interfacial characteristics of the coating layer can be improved compared to the case where the first and second layers mainly consist of crystalline components, and ionic conductivity and / or electronic conductivity can also be improved. In particular, unlike conventional coating layers that use crystalline solid electrolytes, the second layer has amorphous properties, making it easy to form an effective interface between the surface of the positive electrode active material and the solid electrolyte within the positive electrode or the solid electrolyte in the solid electrolyte layer.

[0111] The amorphousness of the above coating layer can be measured through XRD or TEM analysis.

[0112] The first layer and the second layer provided in the coating layer may both be amorphous. This may mean that the components forming the first layer and the second layer include amorphous components. The first layer may include an amorphous oxide, and the second layer may include an amorphous Br-containing sulfide solid electrolyte.

[0113] The above-described positive active material composite includes the coating layer on the surface of the positive active material, thereby improving interfacial contact between the positive active material composite and the solid electrolyte, which can increase ion conductivity, while also having the effect of suppressing side reactions occurring at the interface between the positive active material and the solid electrolyte. When manufacturing an electrode using a dry process capable of high loading, such performance improvement is required, and accordingly, the positive active material composite of the present invention includes two or more layers on the surface of the positive active material, and each layer performs the same or different functions or roles, thereby enabling such performance improvement.

[0114] The thickness of the first layer may be 1 nm or more to 100 nm or less, and the thickness of the second layer may be 10 nm or more to 10 μm or less. For example, the thickness of the first layer may be 1 nm or more to 90 nm or less, 2 nm or more to 80 nm or less, 5 nm or more to 70 nm or less, 10 nm or more to 50 nm or less, 20 nm or more to 40 nm or less, or 3 nm or more to 90 nm or less, 30 nm or more to 80 nm or less, or 40 nm or more to 60 nm or less, but is not limited thereto. For example, the thickness of the second layer is 10 nm or more to 9 µm or less, 10 nm or more to 8 µm or less, 10 nm or more to 7 µm or less, 20 nm or more to 5 µm or less, or 30 nm or more to 10 µm or less, 100 nm or more to 10 µm or less, 200 nm or more to 9 µm or less, 300 nm or more to 8 µm or less, 500 nm or more to 6 µm or less, or 10 nm or more to 1 µm or less, 10 nm or more to 500 nm or less, 10 nm or more to 400 nm or less, 10 nm or more to 300 nm or less, 50 nm or more to 300 nm or less, 80 nm or more to 200 nm or less, or 10 nm or more to 100 nm or less, 10 nm or more to 90 nm or less, 20 nm or more to 80 nm or less, 50 nm or more It may be up to 70 nm or less, 10 nm or more to 50 nm or less, 20 nm or more to 40 nm or less, or 30 nm or more to 90 nm or less, 30 nm or more to 80 nm or less, 40 nm or more to 60 nm or less, or 1 μm or more to 10 μm or less, 2 μm or more to 9 μm or less, or 3 μm or more to 7 μm or less, but is not limited thereto.

[0115] When the thicknesses of the first layer and the second layer satisfy the above range, the interfacial side reaction of the anode active material composite is suppressed, and there is an advantage of improved ion conductivity.

[0116] Average particle size (D) of the above positive active material composite 50 ) may be 3 μm or more to 50 μm or less. For example, the average particle size (D) of the anode active material composite. 50 The average particle size of the anode active material composite may be 5 μm or more to 40 μm or less, 10 μm or more to 40 μm or less, 15 μm or more to 35 μm or less, or 20 μm or more to 30 μm or less, but is not limited thereto. When the average particle size of the anode active material composite satisfies the above range, the interfacial side reaction of the anode active material composite is suppressed, and there is an advantage of improved ion conductivity.

[0117] The above-mentioned positive active material composite can be manufactured by including the step of obtaining a positive active material with a coating layer formed thereon by mixing a positive active material, a Br-containing sulfide solid electrolyte, and a coating material including an oxide.

[0118] The step of mixing the positive active material and the coating material may include a method of directly coating the surface of the positive active material with the coating material. The method of directly coating the surface of the positive active material with the coating material may utilize, but is not limited to, a liquid phase method in which a liquid coating solution containing the coating material is mixed with the positive active material, a ball milling method using mechanical energy, a fluidized bed coating method, a spray drying method, a precipitation method, a dry coating method, etc.

[0119] The step of mixing the positive active material and the coating material may include the step of mixing the positive active material into a coating solution containing the coating material and then drying it.

[0120] Alternatively, the method may include a step of mixing the positive active material and the coating material and then blending the mixture at a speed of 3,500 rpm or more to 6,000 rpm or less. Additionally, after the blending step, the method may further include a step of high-shear mixing the blended mixture in a range of 2,000 rpm or more to 4,000 rpm or less.

[0121] The method for manufacturing the above-mentioned cathode active material composite may be to manufacture it without using a solvent. That is, the cathode active material composite may be manufactured using a dry process method.

[0122] As another example, the anode active material composite may be manufactured by the steps of: mixing the anode active material and the oxide to obtain the anode active material coated with the oxide; and mixing the oxide-coated anode active material with a Br-containing sulfide solid electrolyte in a powder state to obtain the anode active material composite. In this case, the mixing method may be applied in the same manner as the coating, blending, and high-shear mixing described above.

[0123] When the above-mentioned positive active material composite is manufactured using a dry process method as described above, for example, when the mixture blended as described above is manufactured using a high-shear mixing method, the coating layer on the surface of the positive active material has amorphous properties, which can have the effect of improving the electron and / or ion conductivity within the positive.

[0124] For example, the step of mixing the positive electrode active material and the oxide may include a method of directly coating the oxide onto the surface of the positive electrode active material. The method of directly coating the oxide onto the surface of the positive electrode active material may utilize, but is not limited to, a liquid phase method in which a liquid coating solution containing the oxide is mixed with the positive electrode active material, a ball milling method using mechanical energy, a fluidized bed coating method, a spray drying method, a precipitation method, a dry coating method, etc.

[0125] The step of mixing the positive active material and the oxide may include the step of mixing the positive active material into a coating solution containing the oxide and then drying it.

[0126] Alternatively, the method may include a step of mixing the positive active material and the oxide and then blending the mixture at a speed of 3,500 rpm or more to 6,000 rpm or less. Additionally, after the blending step, the method may further include a step of high-shear mixing the blended mixture in a range of 2,000 rpm or more to 4,000 rpm or less.

[0127] Subsequently, the anode active material coated with the oxide and the Br-containing sulfide solid electrolyte can be mixed in a powder state to obtain an anode active material composite using a dry process method without using a solvent.

[0128] The present invention also provides a positive electrode. The positive electrode may comprise the aforementioned positive electrode active material composite, a solid electrolyte, a conductive material, and a binder. As the positive electrode comprises the aforementioned positive electrode active material composite, the lifespan characteristics and / or high-rate characteristics of the secondary battery manufactured therefrom are improved.

[0129] The above-mentioned anode may include an anode current collector and an anode active material layer included on at least one surface of the anode current collector, and the anode active material layer may include the aforementioned anode active material composite. In addition to the anode active material composite, the anode active material layer may further include one or more selected from a conductive material, a binder, and a solid electrolyte. Furthermore, the anode active material layer may further include an additive.

[0130] The above-mentioned positive active material composite may be included in an amount of 60% by weight or more to 99% by weight or less based on the total weight of the positive active material layer, for example, 70% by weight or more to 95% by weight or less, 75% by weight or more to 90% by weight or less, or 80% by weight or more to 90% by weight or less. When the content of the above-mentioned positive active material composite satisfies the above range, interfacial side reactions of the positive active material composite with the solid electrolyte can be suppressed, and the lifespan or performance of the secondary battery can be improved.

[0131] The above positive current collector is not particularly limited as long as it is conductive without causing chemical changes in the battery, and may be made of, for example, copper (Cu), nickel (Ni), aluminum (Al), vanadium (V), gold (Au), platinum (Pt), chromium (Cr), iron (Fe), zinc (Zn), indium (In), germanium (Ge), lithium (Li), magnesium (Mg), stainless steel (e.g., SUS), titanium (Ti), cobalt (Co), or an alloy thereof.

[0132] The anode current collector may have a thickness of 3 μm or more to 500 μm or less, and fine irregularities may be formed on the surface of the anode current collector to increase the adhesion of the anode active material composite. For example, it may be used in various forms such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc. The anode current collector may be omitted depending on the case.

[0133] The above conductive material is used to impart conductivity to the electrode and can be used without special limitations as long as it has electronic conductivity without causing chemical changes. Specific examples include graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, carbon nanotubes, carbon nanofibers; metal powder or metal fibers such as copper, nickel, aluminum, silver; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and one of these alone or a mixture of two or more may be used. For example, the above conductive material may include at least one selected from the group consisting of graphite, carbon black, acetylene black, ketjen black, channel black, furnace black, thermal black, carbon black, carbon nanofibers, carbon nanotubes, fluorinated carbon, metal powder, potassium titanate, zinc oxide, titanium oxide, and polyphenylene derivatives.

[0134] The above conductive material may include a linear conductive material. The above conductive material may include a linear conductive material having a length of 10 μm or more.

[0135] The above-mentioned linear conductive material comprises a conductive material having a fibrous structure, such as a cylindrical type, a tube type, or a fiber type, and may include, for example, carbon nanotubes, carbon nanofibers, nanofibers, or combinations thereof, but is not limited thereto.

[0136] For example, the conductive material may include a linear conductive material having a lower limit selected from 11 μm or more, 12 μm or more, 13 μm or more, 14 μm or more, 15 μm or more, 16 μm or more, 17 μm or more, 18 μm or more, 19 μm or more, and 20 μm or more, and may include a linear conductive material having an upper limit selected from 30 μm or less, 29 μm or less, 28 μm or less, 27 μm or less, 26 μm or less, 25 μm or less, 24 μm or less, 23 μm or less, 22 μm or less, 21 μm or less, 20 μm or less, 19 μm or less, 18 μm or less, 17 μm or less, 16 μm or less, and 15 μm or less. When the conductive material satisfies the above ranges, it can form an electron conduction network within the anode to improve electron conductivity.

[0137] The conductive material may typically be included in an amount of 0.1% to 30% by weight or less with respect to the total weight of the positive active material layer, specifically 0.5% to 20% by weight or less, and more specifically 1% to 10% by weight or less.

[0138] The above binder serves to improve contact between positive active material composites or between positive active material composites and positive components, and to improve adhesion between positive active material composites and positive current collectors. Specific examples include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol (PVA), polyacrylonitrile, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone (PVP), polytetrafluoroethylene (PTFE), polyethylene (PE), polypropylene (PP), ethylene-propylene-diene monomer rubber (EPDM rubber), sulfonated-EPDM, styrene butadiene rubber (SBR), fluororubber, or various copolymers thereof, and one of these alone or a mixture of two or more may be used. For example, the binder may include at least one selected from the group consisting of acrylic binders, polyolefin binders, polyvinyl alcohol binders, polyvinylidene fluoride binders, polytetrafluoroethylene binders, and butadiene rubber binders.

[0139] The above binder may include a fibrous binder. The fibrous binder is a binder that undergoes fibrillation under specific conditions above a phase transition temperature, and when the above binder is included, it can serve as a support, sustain, and / or adhesive between the components included in the anode. Furthermore, by using such a fibrous binder, it is possible to manufacture a solvent-free dry anode. Specifically, the binder may include a polytetrafluoroethylene (PTFE)-based binder, but is not limited thereto.

[0140] The binder may be included in an amount of 0.1% to 30% by weight or less with respect to the total weight of the positive active material layer, specifically 0.5% to 20% by weight or less, and more specifically 1% to 10% by weight or less.

[0141] The above solid electrolyte is a solid electrolyte included in the above positive active material layer and may include oxide-based solid electrolytes, sulfide-based solid electrolytes, polymer-based solid electrolytes, or halide-based solid electrolytes, but is not limited thereto, and any solid electrolyte other than a conventional liquid electrolyte may be used without limitation.

[0142] As the above oxide-based solid electrolyte, for example, Li xa La ya TiO3 [xa=0.3~0.7, ya=0.3~0.7](LLTO), Li xb La yb Zr zb Mbb mb O nb (Mbb is at least one element among Al, Mg, Ca, Sr, V, Nb, Ta, Ti, Ge, In, and Sn, xb satisfies 5≤xb≤10, yb satisfies 1≤yb≤4, zb satisfies 1≤zb≤4, mb satisfies 0≤mb≤2, and nb satisfies 5≤nb≤20), Li xc B yc Mcc zc O nc (Mcc is at least one element among C, S, Al, Si, Ga, Ge, In, and Sn, xc satisfies 0≤xc≤5, yc satisfies 0≤yc≤1, zc satisfies 0≤zc≤1, and nc satisfies 0≤nc≤6), Li xd (Al, Ga) yd (Ti, Ge) zd Si ad P md O nd(However, 1≤xd≤3, 0≤yd≤1, 0≤zd≤2, 0≤ad≤1, 1≤md≤7, 3≤nd≤13), Li (3-2xe) Mee xe DeeO(xe represents a number between 0 and 0.1, and Mee represents a divalent metal atom. Dee represents a halogen atom or a combination of two or more halogen atoms), Li xf Si yf O zf (1≤xf≤5, 0 <yf≤3, 1≤zf≤10), Li xg S yg O zg (1≤xg≤3, 0 <yg≤2, 1≤zg≤10), Li3BO3-Li2SO4, Li2O-B2O3-P2O5, Li2O-SiO2, Li6BaLa2Ta2O 12 , Li3PO (4-3 / 2w) N w (w is w<1), Li having a LISICON (Lithium superionic conductor) type crystal structure 3.5 Zn 0.25 GeO4, La having a perovskite-type crystal structure 0.55 Li 0.35 LiTi2P3O having a TiO3, NASICON (Sodium(Na) superionic conductor) type crystal structure 12 , Li 1+xh+yh (Al, Ga) xh (Ti, Ge) 2-xh Si yh P3- yh O 12 (where 0≤xh≤1, 0≤yh≤1), Li7La3Zr2O having a garnet-type crystal structure 12Examples include (LLZO). Alternatively, phosphorus compounds containing Li, P, and O may also be used. Examples include lithium phosphate (Li3PO4), LiPON in which some of the oxygen in lithium phosphate is substituted with nitrogen, LiPOD1 (where D1 is at least one selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Ru, Ag, Ta, W, Pt, and Au, etc.). Alternatively, LiA1ON (where A1 is at least one selected from Si, B, Ge, Al, C, and Ga, etc.) may also be used.

[0143] The above sulfide-based solid electrolyte contains sulfur atoms (S), has ionic conductivity of metals belonging to Group 1 or Group 2 of the periodic table, and may have electronic insulation properties. The above sulfide-based solid electrolyte preferably contains at least Li, S, and P as elements and has lithium ion conductivity, but may include other elements other than Li, S, and P depending on the purpose or case.

[0144] Specific sulfide-based solid electrolytes include, for example, Li2S-P2S5, Li2S-P2S5-LiCl, Li2S-P2S5-H2S, Li2S-P2S5-H2S-LiCl, Li2S-LiI-P2S5, Li2S-LiI-Li2O-P2S5, Li2S-LiBr-P2S5, Li2S-Li2O-P2S5, Li2S-Li3PO4-P2S5, Li2S-P2S5-P2O5, Li2S-P2S5-SiS2, Li2S-P2S5-SiS2-LiCl, Li2S-P2S5-SnS, Li2S-P2S5-Al2S3, Li2S-GeS2, Li2S-GeS2-ZnS, Li2S-Ga2S3, Li2S-GeS2-Ga2S3, Li2S-GeS2-P2S5, Li2S-GeS2-Sb2S5, Li2S-GeS2-Al2S3, Li2S-SiS2, Li2S-Al2S3, Li2S-SiS2-Al2S3, Li2S-SiS2-P2S5, Li2S-SiS2-P2S5-LiI, Li2S-SiS2-LiI, Li2S-SiS2-Li4SiO4, Li2S-SiS2-Li3PO4, Li 10 GeP2S 12 , or a azirodite-based sulfide solid electrolytes represented by Li6PS5X (where X is one or more halogen elements) may be used.

[0145] If the above solid electrolyte includes a sulfide-based solid electrolyte, the anode may include a second sulfide-based solid electrolyte, and in this case, the second sulfide-based solid electrolyte may be the same as or different from the Br-containing sulfide solid electrolyte (first sulfide-based solid electrolyte).

[0146] The above polymer-based solid electrolyte includes polymer materials that are ion-conducting materials and are typically used as solid electrolyte materials for all-solid-state batteries, but is not specifically limited thereto. The above polymer-based solid electrolyte may include, for example, polyether-based polymers, polycarbonate-based polymers, acrylate-based polymers, polysiloxane-based polymers, phosphazene-based polymers, polyethylene oxide (PEO), polyethylene derivatives, alkylene oxide derivatives, phosphate ester polymers, polyaisation lysine, polyester sulfide, polyvinyl alcohol, polyvinylidene fluoride, or polymers containing ionic dissociators. Alternatively, the above polymer-based solid electrolyte may include, as a polymer resin, branched copolymers, comb-like polymers, and cross-linked polymer resins, etc., in which amorphous polymers such as polymethyl methacrylate (PMMA), polycarbonate, polysiloxane, and / or phosphazene are copolymerized as comonomers to a polyethylene oxide (PEO) main chain.

[0147] The above polymer-based solid electrolyte may include a gel-type polymer electrolyte. The above gel-type polymer electrolyte comprises an organic electrolyte containing a lithium salt and a polymer resin, wherein the organic electrolyte comprises 60 to 400 parts by weight per 100 parts by weight of the polymer resin. The polymer resin applied to the above gel-type polymer electrolyte is not limited to specific components, but may include, for example, polyvinyl chloride (PVC), poly(Methyl methacrylate) (PMMA), polyacrylonitrile (PAN), poly(vinylidene fluoride) (PVDF), or poly(vinylidene fluoride)-hexafluoropropylene (PVDF-HFP).

[0148] The above-mentioned halide-based solid electrolyte may, for example, contain a halogen element as the main component of anion. Containing a halogen element as the main component of anion may mean that the proportion (molar ratio) of the halogen element is the highest among all anions constituting the halide-based solid electrolyte. The ratio of the halogen (X) element to all anions constituting the above-mentioned halide-based solid electrolyte may, for example, be 50 mol% or more, 70 mol% or more, 90 mol% or more, or 100 mol%. The halogen element may be one or more types. The above-mentioned halide-based solid electrolyte may, for example, not contain a sulfur element (S element). The above-mentioned halide-based solid electrolyte may, for example, contain a Li element, an M element (M is a metal other than Li), and an X element. X may, for example, be F, Cl, Br, I, or a combination thereof. The above halide-based solid electrolyte may include, for example, Br or Cl as X. The above halide-based solid electrolyte may include, for example, a metal element such as Sc, Y, B, Al, Ga, or In as M. The composition of the above halide-based solid electrolyte is, for example, Li 6-3a M a Br b Cl c (M is a metal other than Li, and 0 <a<2, 0≤b≤6, 0≤c≤6, b+c=6)일 수 있다. 상기 할라이드계 고체 전해질은 예를 들어 Li3YBr6, Li3YCl6, 또는 Li3YBr2Cl4등일 수 있다.

[0149] The above solid electrolyte may be included in an amount of 5% or more to 20% or less based on the total weight of the anode active material layer, specifically in an amount of 5% or more to 18% or less, or in an amount of 10% or more to 18% or less. When the content of the above solid electrolyte satisfies the above range, contact between the anode active material and the solid electrolyte can be maintained, and ion conductivity can be improved to make the electrochemical performance excellent.

[0150] Average particle size (D) of the above solid electrolyte 50 ) may be 0.01 μm or more to 1 μm or less. For example, the average particle size (D) of the solid electrolyte. 50 ) may be 0.05 μm or more to 1 μm or less, 0.1 μm or more to 1 μm or less, 0.1 μm or more to 0.9 μm or less, 0.1 μm or more to 0.8 μm or less, 0.2 μm or more to 0.7 μm or less, or 0.3 μm or more to 0.6 μm or less, but is not limited thereto. The average particle size (D) of the solid electrolyte is 50 If ) is less than 0.01 μm, there is a problem of reduced ionic conductivity, and if it exceeds 1 μm, interfacial contact with the positive electrode active material composite decreases, which may lead to inferior performance of the secondary battery. The average particle size (D) of the solid electrolyte above 50 When the above range is satisfied, the interfacial contact between the positive active material composite and the solid electrolyte is improved, and the electrochemical performance of the secondary battery is improved.

[0151] The above-mentioned positive active material layer may further include additives. The additives may further include, for example, fillers, coating agents, dispersants, thickeners, ion conductivity aids, etc., and any known material generally used in electrodes may be used without limitation.

[0152] The thickness of the positive active material layer may be 50 μm or more to 500 μm or less. For example, the thickness of the positive active material layer may be 55 μm or more to 400 μm or less, 60 μm or more to 300 μm or less, 65 μm or more to 200 μm or less, or 70 μm or more to 100 μm or less, but is not limited thereto.

[0153] The above-mentioned anode may be manufactured according to a conventional anode manufacturing method, except for using the above-mentioned anode active material composite. For example, it may be manufactured by applying a composition for forming an anode active material layer, comprising the above-mentioned anode active material composite and optionally a binder, a conductive material, and / or a solid electrolyte, onto an anode current collector, followed by drying and rolling.

[0154] The step of applying the above-mentioned composition for forming the positive electrode active material layer can be performed using a general coating formation method. For example, wet coating methods such as gravure coating, slot die coating, spin coating, spray coating, bar coating, and immersion coating; and dry coating methods such as thermal evaporation, electron beam evaporation, chemical vapor deposition (CVD), and sputtering may be used, but are not limited thereto.

[0155] The above anode can be manufactured by a wet process method. For example, the composition for forming the anode active material layer may further include a solvent, and the types and contents of the anode active material, binder, conductive material, and additive are as described above.

[0156] The above solvent may be a solvent commonly used in the relevant technical field, and may include dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water, and one of these alone or a mixture of two or more may be used. The amount of the above solvent used is sufficient if it is sufficient to dissolve or disperse the anode active material composite, conductive material, binder, etc., considering the coating thickness of the slurry and the manufacturing yield, and to have a viscosity that can exhibit excellent thickness uniformity when coated for anode manufacturing thereafter.

[0157] The above anode may also be manufactured by casting the composition for forming the anode active material layer onto a separate support, and then laminating the film obtained by peeling off from the support onto an anode current collector.

[0158] The above anode can be manufactured by a dry process method capable of implementing high loading. For example, the above anode can be manufactured by a fiberization method. The composition for forming an anode active material layer including the above anode active material composite can be manufactured by including a calendering or sheeting process using a roll, but is not limited thereto.

[0159] For example, the anode can be manufactured by a method for manufacturing an anode comprising: (A) a step of forming an anode active material layer; and (B) a step of stacking the anode active material layer and the anode current collector.

[0160] Specifically, the step of forming the (A) positive active material layer may include (a) mixing the positive active material composite, conductive material, binder, and solid electrolyte, and then forming them into a film form through a sheeting / calendaring process.

[0161] In step (a) above, the positive active material composite, conductive material, binder, and solid electrolyte can be applied in the same way as the aforementioned positive active material composite, conductive material, binder, and solid electrolyte.

[0162] In step (a) above, an anode active material layer can be formed by mixing the anode active material composite, conductive material, binder, and solid electrolyte, and then molding them into a film shape through a sheeting / calendering step. At this time, the binder becomes fibrous through the sheeting / calendering step.

[0163] The above-mentioned sheeting / calendering process may utilize one or more pairs of rollers. By utilizing one or more pairs of rollers in the above-mentioned sheeting / calendering process, the binder can be fiberized by sheeting and formed into a film by calendering. At the same time, the thickness of the film can be controlled through the one or more pairs of rollers.

[0164] The above-mentioned seating / calendering process may be performed at a temperature of 20°C or higher to 200°C or lower. Specifically, the range may consist of one lower limit selected from 20°C or higher, 30°C or higher, 40°C or higher, 50°C or higher, 60°C or higher, 70°C or higher, and 80°C or higher, and one upper limit selected from 200°C or lower, 180°C or lower, 160°C or lower, 140°C or lower, 120°C or lower, and 100°C or lower.

[0165] If the temperature of the above sheeting / calendering process is less than 20 ℃, the fiberization of the binder may occur less, and the strength of the positive active material layer may decrease. If the temperature exceeds 200 ℃, the strength of the positive active material layer may not increase further even if the temperature increases, or there is a risk that the raw materials may deteriorate.

[0166] The above-mentioned sheeting / calendering process may be performed for 1 loop or more and 50 loops or less. Specifically, if the number of loops of the above-mentioned sheeting / calendering process is less than 1 loop, the binder may not be fiberized, and if it exceeds 50 loops, the fiberization may proceed excessively, so the strength of the anode active material layer may not increase further or processability may deteriorate. Specifically, the number of loops of the above-mentioned sheeting / calendering process may be a range consisting of one lower limit selected from 1 or more, 5 or more, 10 or more, 15 or more, 20 or more, 23 or more, and 25 or more, and one upper limit selected from 50 or less, 45 or less, 40 or less, 35 or less, and 30 or less.

[0167] The orientation of the above-mentioned sheeting / calendering process can be performed uniaxially or biaxially. Here, uniaxial means that the sheeting / calendering proceeds in one direction, and biaxial means that after performing sheeting / calendering in one direction, sheeting / calendering is performed alternately in the horizontal and vertical directions of the positive active material layer. When the above-mentioned sheeting / calendering process is performed biaxially, fiberization can proceed evenly in multiple directions, thereby further improving the strength of the positive active material layer.

[0168] The step of stacking the positive active material layer (B) and the positive current collector may include the step of manufacturing a dry positive by stacking the positive active material layer formed in step (A) on at least one surface of the positive current collector.

[0169] The present invention provides a secondary battery. The secondary battery comprises the aforementioned positive electrode and, in addition to the positive electrode, may further comprise a negative electrode and a separator disposed between the positive electrode and the negative electrode.

[0170] In addition to the aforementioned anode active material composite, the above anode may further comprise one or more selected from the aforementioned conductive material, binder, and solid electrolyte.

[0171] The above cathode may include a cathode current collector and a cathode active material layer included on at least one surface of the cathode current collector.

[0172] The above-mentioned negative current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, copper, stainless steel (e.g., SUS), aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface treated or coated with carbon, nickel, titanium, or silver, or aluminum-cadmium alloy may be used.

[0173] The above-mentioned negative current collector can typically have a thickness of 3 μm or more to 500 μm or less, and, similar to the positive current collector, fine irregularities can be formed on the surface of the negative current collector to strengthen the bonding force of the negative active material. For example, it can be used in various forms such as a film, sheet, foil, net, porous body, foam, or nonwoven fabric.

[0174] The above-mentioned cathode active material layer may optionally include a binder, a conductive material, and / or additives, etc., together with the cathode active material. The above-mentioned cathode active material layer may be manufactured, for example, by applying a composition for forming a cathode active material layer containing the cathode active material, etc., onto a cathode current collector and drying it, or by casting the composition for forming a cathode active material layer onto a separate support and then laminating the film obtained by peeling it off from the support onto the cathode current collector. The composition for forming a cathode active material layer may further include a solvent, and the solvent may be selected from examples of solvents included in the aforementioned composition for forming an anode active material layer.

[0175] As the above-mentioned negative electrode active material, a compound capable of reversible intercalation and deintercalation of lithium may be used. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, or amorphous carbon; metallic compounds capable of alloying with lithium, such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Ag, Au, In alloys, Si alloys, Sn alloys, or Al alloys; and SiO₂ β Examples include metal oxides capable of doping and dedoping lithium, such as (0<β≤2), SnO2, vanadium oxide, or lithium vanadium oxide; or the above metallic compounds, such as Si-C complexes or Sn-C complexes; or complexes thereof, and any one or more of these may be used. Additionally, a metallic lithium thin film may be used as the negative electrode active material.

[0176] The above carbonaceous materials may include both low-crystallinity carbon and high-crystallinity carbon. Representative examples of low-crystallinity carbon include soft carbon and hard carbon, while representative examples of high-crystallinity carbon include amorphous, plate-like, flake-like, spherical, or fibrous natural or artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, meso-carbon microbeads, mesophase pitches, or high-temperature calcined carbon such as petroleum or coal tar pitch-derived cokes.

[0177] In addition, the above carbonaceous material is amorphous carbon, inorganic material, or Si, SiO β(0<β≤2), it may be coated with a Si-based compound such as Si-C, and the carbonaceous material may be amorphous carbon, inorganic material, or Si, SiO β (0<β≤2), it may also exist in a mixed state mixed with Si-based compounds such as Si-C.

[0178] The thickness of the above-mentioned negative electrode active material layer may be 10 μm or more to 500 μm or less. For example, the thickness of the above-mentioned negative electrode active material layer may be 20 μm or more to 400 μm or less, 30 μm or more to 300 μm or less, 40 μm or more to 200 μm or less, or 50 μm or more to 100 μm or less, but is not limited thereto. Alternatively, the thickness of the negative electrode active material layer may be, for example, 50 μm or more to 500 μm or less, 50 μm or more to 400 μm or less, 70 μm or more to 300 μm or less, or 80 μm or more to 200 μm or less, but is not limited thereto. Alternatively, the thickness of the negative active material layer may be, for example, 50 μm or more to 500 μm or less, 50 μm or more to 400 μm or less, 70 μm or more to 300 μm or less, or 80 μm or more to 200 μm or less, but is not limited thereto.

[0179] In another example, the above-mentioned cathode may be an anodeless cathode that does not contain a cathode active material that absorbs or releases lithium immediately after battery manufacturing or after discharge, and in which a lithium metal or lithium alloy is formed during the battery charging process to form the cathode active material.

[0180] In cases where the above-mentioned negative electrode active material is omitted, the negative electrode may include only a negative electrode current collector, or the negative electrode active material layer included on the negative electrode current collector may include a lithium-affinity material. In cases where the negative electrode is an anodeless negative electrode, the negative electrode active material layer may include a non-negative electrode coating layer containing a lithium-affinity material.

[0181] The above lithium-affinity material includes a material capable of forming an alloy or compound with lithium, and may include an element capable of forming an alloy or compound with lithium.

[0182] The above lithium-affinity material may include one or more lithium-affinity elements or lithium-affinity compounds. The lithium-affinity elements may include one or more selected from gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), indium (In), magnesium (Mg), aluminum (Al), bismuth (Bi), tin (Sn), chromium (Cr), copper (Cu), tungsten (W), germanium (Ge), lead (Pb), antimony (Sb), cobalt (Co), manganese (Mn), titanium (Ti), zirconium (Zr), iron (Fe), and zinc (Zn).

[0183] The above lithium-affinity compound may include one or more selected from lithium carbonate, lithium titanate, or oxides, nitrides, halides, sulfides, carbides, hydrides, cyanides, or hydroxides of the lithium-affinity element.

[0184] The above lithium-affinity material may include one or more lithium-affinity elements or lithium-affinity compounds, and the lithium-affinity elements may be one or more selected from gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), indium (In), magnesium (Mg), aluminum (Al), bismuth (Bi), tin (Sn), chromium (Cr), copper (Cu), tungsten (W), germanium (Ge), lead (Pb), antimony (Sb), and zinc (Zn), and the lithium-affinity compounds may be one or more selected from lithium carbonate, lithium titanate, or oxides, nitrides, halides, sulfides, carbides, hydrides, cyanides, or hydroxides of the lithium-affinity elements.

[0185] The lithium-affinity material may include a metal of the lithium-affinity element. The lithium-affinity material may include an alloy of the lithium-affinity element. Alternatively, the lithium-affinity material may include one or more compounds selected from oxides, nitrides, halides, sulfides, carbides, hydrides, cyanides, or hydroxides of the lithium-affinity element.

[0186] The above lithium-affinity material may include an alloy of the above lithium-affinity element, and an alloy of lithium and the above lithium-affinity element (Li-M 1 alloy), alloy of other metallic elements and the above lithium affinity element (M 1 -M 2 It may include two or more alloys selected from the above lithium affinity elements), or, but is not limited thereto. For example, Si-M 2 Alloy (M 2 is an alkali metal, alkaline earth metal, Group 13 element, Group 14 element, transition metal, rare earth element, or combination thereof, but is not Si) or Sn-M 2 Alloy (M 2 may include alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements, transition metals, rare earth elements, or combinations thereof (but not Sn), etc. The above M 2 may be Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ge, P, As, Sb, Bi, S, Se, Te, Po, or a combination thereof, and said M 1It may be gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), indium (In), magnesium (Mg), aluminum (Al), bismuth (Bi), tin (Sn), chromium (Cr), copper (Cu), tungsten (W), germanium (Ge), lead (Pb), antimony (Sb), cobalt (Co), manganese (Mn), titanium (Ti), zirconium (Zr), iron (Fe), zinc (Zn), or a combination thereof.

[0187] For example, the lithium-affinity compound is copper(I) oxide (Cu2O), copper(II) oxide (CuO), zinc oxide (ZnO), cobalt(II) oxide (CoO), cobalt(III) oxide (Co2O3), manganese(II) oxide (MnO), manganese(III) oxide (Mn2O3), silicon oxide (SiO2). x )(0≤x≤2), titanium dioxide (TiO2), aluminum oxide (Al2O3), zinc peroxide (ZnO2), indium oxide (In2O3), silver titanate (AgTiO3), aluminum titanate (Al2TiO5), dicalcium silicate (Ca2SiO4), lithium titanate (Li4Ti5O 12Metal oxides such as ), niobium pentoxide (Nb2O5), LLZO-based (Li-La-Zr-O) compounds, LLZTO-based (Li-La-Zr-Ta-O) compounds, LLTO-based (Li-La-Ti-O) compounds, LISICON (Lithium superionic conductor), LZPO-based (Li-Zr-PO) compounds, LZSP-based (Li-Zr-Si-PO) compounds, or LTPO-based (Li-Ti-PO) compounds; metal sulfides such as titanium sulfide (TiS2), iron sulfide (FeS), silver sulfide (Ag2S), indium sulfide (In2S3), copper sulfide (CuS), germanium sulfide (GeS), zinc sulfide (ZnS), germanium disulfide (GeS2), or tungsten disulfide (WS2); Metal nitrides such as titanium nitride (TiN), silicon nitride (Si3N4), lithium nitride (Li3N), lithium aluminum nitride (Li3AlN2), or lithium phosphate nitride (LiPON); metal fluorides such as lithium fluoride (LiF), silver fluoride (AgF), magnesium fluoride (MgF2), nickel fluoride (NiF2), zinc fluoride (ZnF2), manganese(II) fluoride (MnF2), manganese(III) fluoride (MnF3), lithium tetrafluoroaluminate (LiAlF4), lithium hexafluorophosphate (LiPF6), lithium hexafluoroarsenate (LiAsF6), lithium hexafluoroantimonate (LiSbF6), lithium tetrafluoroborate (LiBF4), and lithium difluoro(oxalato)borate (LiBF2(C2O4)). Metal carbides such as tungsten carbide (WC); or lithium chloride (LiCl), lithium bromide (LiBr), lithium iodide (LiI), lithium nitrate (LiNO3), lithium perchlorate (LiClO4), lithium decachlorodecarborate (Li2B 10 Cl 10It may include compounds such as lithium trifluoromethanesulfonate (LiCF3SO3), lithium trifluoroacetate (LiCF3CO2), lithium tetrachloroaluminate (LiAlCl4), lithium methanesulfonate (CH3SO3Li), lithium thiocyanate (LiSCN), lithium tris(trifluoromethanesulfonyl)methide (LiC(CF3SO2)3), lithium bis(trifluoromethanesulfonyl)imide ((CF3SO2)2NLi), lithium bis(fluorosulfonyl)imide ((FSO2)2NLi), lithium orthoborate (Li3BO3), lithium tetraborate (Li2B4O7), lithium metaborate (LiBO2), or lithium bis(oxalato)borate (LiB(C2O4)2), but is not limited thereto.

[0188] When including a lithium-affinity material as described above, it has the effect of suppressing lithium dendrite formation by lowering the lithium nucleation energy when lithium or lithium alloy is deposited or plated during charging and discharging.

[0189] In addition, the above-mentioned non-cathode coating layer may further include a carbon material, and the carbon material comprises at least one selected from artificial graphite, natural graphite, graphitized carbon fiber, low-crystallinity carbon, high-crystallinity carbon, and amorphous carbon, and may serve to induce the formation of a metal layer comprising lithium metal or a lithium alloy between the non-cathode coating layer and the cathode current collector by transferring lithium ions supplied from the anode toward the direction of the negative electrode current collector to which negative charge is supplied.

[0190] The above carbon material may include amorphous carbon, and may be one or more selected from the group consisting of, for example, carbon black, acetylene black, furnace black, Ketjen black, and graphene, but is not limited thereto, and any amorphous carbon that can be used in a secondary battery may be used without limitation.

[0191] The carbon material and the lithium-affinity material in the above-mentioned non-cathode coating layer may be included in a weight ratio of 1:1 or more to 10:1 or less, 1:1 or more to 5:1 or less, 1:1 or more to 4:1 or less, or 1.5:1 or more to 3:1 or less, but are not limited thereto.

[0192] The thickness of the above-mentioned non-cathode coating layer may be, for example, 1 μm or more to 100 μm or less, 5 μm or more to 80 μm or less, 10 μm or more to 50 μm or less, or 10 μm or more to 30 μm or less.

[0193] In the case where the above-mentioned negative electrode is an anodeless negative electrode, the secondary battery may precipitate lithium within the negative electrode during charging. Specifically, the secondary battery may further include a metal containing lithium or a lithium alloy and / or a metal layer thereof between the negative electrode current collector and the non-negative electrode coating layer, on the side of the non-negative electrode coating layer that does not face the separator (or solid electrolyte layer), and / or within the non-negative electrode coating layer upon charging. 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, etc., but is not limited thereto; any alloy used as a lithium alloy in the relevant technical field is acceptable.

[0194] The metal or metal layer included between the above-mentioned cathode current collector and the non-cathode coating layer, and / or within the non-cathode coating layer, may be composed of one of these alloys or lithium, or may be composed of various types of alloys.

[0195] The thickness of the metal layer containing the lithium or lithium alloy may be, for example, 1 μm or more to 1,000 μm or less, 1 μm or more to 500 μm or less, 1 μm or more to 200 μm or less, 1 μm or more to 150 μm or less, 1 μm or more to 100 μm or less, or 1 μm or more to 50 μm or less. When the metal layer satisfies the above range, it can perform the role of a lithium reservoir well and the cycle characteristics can be improved.

[0196] The above metal layer may be formed, for example, by precipitation between the negative current collector and the non-negative coating layer, or on the surface of the non-negative coating layer that does not face the separator or solid electrolyte layer, by charging after assembly of the secondary battery. When the metal layer is formed by charging after assembly of the secondary battery, the region between the negative current collector and the non-negative coating layer, or on the surface of the non-negative coating layer that does not face the separator, may, for example, be a lithium-free region that does not contain lithium in the initial state or after discharge of the secondary battery.

[0197] The above separator can be used without particular restrictions as long as it is a separator used in general secondary batteries, and it is particularly desirable that it has low resistance to ion movement of the electrolyte and excellent electrolyte moisture retention capacity.

[0198] Specifically, the above separator may be a porous polymer film, for example, a porous polymer film made of a polyolefin-based polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof. Alternatively, a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fibers or polyethylene terephthalate fibers, may be used. Furthermore, a coated separator containing a ceramic material or a polymer material may be used to ensure heat resistance or mechanical strength, and may optionally be used in a single-layer or multi-layer structure. The separator may be omitted in some cases.

[0199] The above separator may have a thickness of 1 μm or more to 100 μm or less, or 5 μm or more to 50 μm or less. If the thickness of the separator is less than 1 μm, the function of the separator may not be fully exerted and deterioration of mechanical properties may occur, and if it exceeds 100 μm, the characteristics of the battery may deteriorate during high-rate charging and discharging.

[0200] The above secondary battery may include an electrolyte. Examples of the electrolytes that can be used in the manufacture of secondary batteries include organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, or molten inorganic electrolytes, but are not limited to these.

[0201] The above electrolyte may include, for example, an organic solvent and / or a lithium salt.

[0202] The above organic solvent may be used without special restrictions as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, the above organic solvent may include ester-based solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether-based solvents such as dibutyl ether or tetrahydrofuran; ketone-based solvents such as cyclohexanone; and aromatic hydrocarbon-based solvents such as benzene or fluorobenzene. Carbonate-based solvents such as dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), or propylene carbonate (PC); alcohol-based solvents such as ethyl alcohol or isopropyl alcohol; nitriles such as R-CN (where R is a straight-chain, branched, or cyclic hydrocarbon group having C2 to C20 structures and may include a double bond, a directional ring, or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes may be used. Among these, a carbonate-based solvent is preferred, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate, etc.) having high ionic conductivity and high dielectric constant that can improve the charge / discharge performance of the battery, and a low-viscosity linear carbonate-based compound (e.g., ethylmethyl carbonate, dimethyl carbonate or diethyl carbonate, etc.) is more preferred.In this case, using a mixture of cyclic carbonate and chain carbonate in a volume ratio of about 1:1 to about 1:9 can simultaneously satisfy high dielectric constant and low viscosity characteristics, and excellent ionic conductivity characteristics can be achieved, so the performance of the electrolyte can be excellent.

[0203] In addition to the above electrolyte components, the above electrolyte may further include one or more additives for the purpose of improving the lifespan characteristics of the battery, suppressing the decrease in battery capacity, and improving the discharge capacity of the battery, such as, for example, a haloalkylene carbonate-based compound such as difluoroethylene carbonate, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylene diamine, n-glyme, triamide hexaphosphate, nitrobenzene derivative, sulfur, quinone imine dye, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, or aluminum trichloride. In this case, the above additive may be included in an amount of 0.1% by weight or more to 5% by weight or less based on the total weight of the electrolyte.

[0204] The above lithium salt can be used without special restrictions as long as it is a compound capable of providing lithium ions used in secondary batteries. For example, the above lithium salt is Li as a cation + It includes, and as anion, F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , AlO4 - , AlCl4 - , PF6 - , BF6 - , SF6 - , B 10 Cl 10 - , BF2C2O4 - , BC4O8 -, PF4C2O4 - , PF2C4O8 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , F3SO3 - , C4F9SO3 - , CF3CF2SO3 - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , CH3SO3 - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - and (CF3CF2SO2)2N - It may include at least one selected from a group consisting of

[0205] Specifically, the lithium salts mentioned above are LiCl, LiBr, LiI, LiBF4, LiClO4, LiAlO4, LiAlCl4, LiPF6, LiSbF6, LiAsF6, LiB 10 Cl 10 Examples include at least one selected from the group consisting of LiBOB (LiB(C2O4)2), LiCF3SO3, LiTFSI (LiN(SO2CF3)2), LiFSI (LiN(SO2F)2), LiCH3SO3, LiCF3CO2, LiCH3CO2, and LiBETI (LiN(SO2CF2CF3)2). Specifically, the lithium salt may include a single substance or a mixture of two or more selected from the group consisting of LiBF4, LiClO4, LiPF6, LiBOB (LiB(C2O4)2), LiCF3SO3, LiTFSI (LiN(SO2CF3)2), LiFSI (LiN(SO2F)2), and LiBETI (LiN(SO2CF2CF3)2).

[0206] The lithium salt may be included in the electrolyte at a concentration of 0.1 M or more and 4 M or less, specifically at a concentration of 0.1 M or more and 2 M or less, and more specifically at a concentration of 0.8 M or more and 1.6 M or less. When the lithium salt is included in the electrolyte at a concentration within the above range, the electrolyte has appropriate conductivity and viscosity, so it can exhibit excellent electrolyte performance, and lithium ions can move effectively, thereby improving the output characteristics of the secondary battery.

[0207] The above electrolyte may include a solid electrolyte, and if the solid electrolyte is included, the solid electrolyte can take the place of the separator, so the solid electrolyte layer may be included instead of the separator.

[0208] The above solid electrolyte layer is interposed between the anode and the cathode and can electrically insulate the anode active material layer and the cathode active material layer while allowing lithium ions to pass through.

[0209] The above solid electrolyte layer may include oxide-based solid electrolytes, sulfide-based solid electrolytes, polymer-based solid electrolytes, or halide-based solid electrolytes, but is not limited thereto, and any solid electrolyte or gel electrolyte other than a conventional liquid electrolyte may be used without limitation.

[0210] The above-described solid electrolyte layer may be subject to the same provisions regarding the solid electrolyte described above, and if the above-described solid electrolyte layer includes a sulfide-based solid electrolyte, the above-described solid electrolyte layer may include a third sulfide-based solid electrolyte, and in this case, the Br-containing sulfide solid electrolyte (first sulfide-based solid electrolyte), the second sulfide-based solid electrolyte, and the third sulfide-based solid electrolyte may be identical or different from each other. Alternatively, only parts may be identical and parts may be different.

[0211] The solid electrolyte layer may further include, for example, a binder. As the binder, a water-based binder, an organic binder, or a combination thereof may be used. The binder may be, for example, polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, diacetylcellulose, polyvinylidene fluoride, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, a polymer containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene, fluoride, polyethylene, polypropylene, styrene-butadiene rubber, styrene-butadiene rubber acrylate, epoxy resin, nylon, or a combination thereof. As the water-based binder, for example, styrene-butadiene rubber, carboxymethylcellulose, or a combination thereof may be used. For example, the above organic binder may be polytetrafluoroethylene, polyvinylidene fluoride, or a combination thereof, but is not limited thereto, and known binders may be used without limitation as long as they do not impede the purpose of the present invention. The above solid electrolyte layer may contain, for example, 5 weight percent or less of the binder.

[0212] The thickness of the solid electrolyte layer may be 10 μm or more to 50 μm or less, or 10 μm or more to 40 μm or less. When the thickness of the solid electrolyte layer satisfies the above range, the function as a separator can be sufficiently performed and the deterioration of mechanical properties during charging and discharging can be prevented.

[0213] The above secondary battery may be pouch-type, prismatic, or cylindrical, and its shape and size may be applied without limitation as long as they are commonly used for secondary batteries. Additionally, the above secondary battery may further include a case capable of sealing the electrode assembly, such as a container, pouch, pack, or module, for housing the electrode assembly including the positive electrode, separator, and negative electrode. The case may optionally further include a sealing member.

[0214] The above secondary battery may be manufactured by manufacturing the positive electrode, separator, and negative electrode respectively, then stacking and / or laminating these layers, and then injecting an electrolyte, but is not limited thereto.

[0215] Or, if the secondary battery includes a solid electrolyte layer, the secondary battery may be an all-solid-state battery, and in this case, it may be manufactured by stacking and / or laminating the layers after manufacturing the positive electrode, the solid electrolyte layer, and the negative electrode, respectively, but is not limited thereto.

[0216] The above all-solid-state battery can be manufactured according to a method for manufacturing an all-solid-state battery comprising the step of sequentially stacking the positive electrode, the solid electrolyte layer, and the negative electrode, and then applying pressure.

[0217] The above-mentioned pressurizing step may be used without limitation as long as it utilizes a method or equipment for pressurizing an all-solid-state battery. Specifically, the above-mentioned pressurizing step may include, but is not limited to, pressurizing methods such as isostatic pressurization, warm isostatic pressurization (WIP), roll press, or jig press.

[0218] The above pressurizing step may be performed at a temperature of room temperature to 100°C at a pressure of 100 MPa or more to 1,000 MPa or less, but is not limited thereto. When the above temperature and pressure ranges are satisfied, the interfacial characteristics of the anode, cathode, and solid electrolyte layer may be improved.

[0219] The present invention provides a battery module comprising the secondary battery as a unit cell, a battery pack comprising the battery module or the secondary battery, or an electric device comprising the battery pack as a power source.

[0220] The above electric device may include, but is not limited to, a power tool that moves by receiving power from an electric motor; electric vehicles including electric vehicles (EV), hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV), etc.; electric two-wheeled vehicles including electric bicycles (E-bike) and electric scooters (E-scooter); electric golf carts; power storage systems, etc.

[0221] In the following, the present invention is described in detail with reference to examples to specifically explain the disclosure of the present invention as described above and the intended functions and effects of the present invention. However, the examples may be modified in various different forms, and the scope of this specification is not to be interpreted as being limited only to these examples. It is emphasized that the examples are provided to represent the present invention and to explain it more specifically to those skilled in the art.

[0222]

[0223] <Example 1>

[0224] Average particle size (D 50 LiNi as a positive electrode active material with a thickness of 6 µm 0.8 Co 0.1 Mn 0.1 O2 was prepared and LiNbO3 was coated on the surface of the positive active material to obtain a positive active material coated with LiNbO3.

[0225] Next, the Br-containing sulfide solid electrolyte was mixed with the LiNbO3-coated cathode active material and mixed for 1 minute at 5,000 rpm using a Lab Blender (Waring). Then, the mixture was subjected to high-shear mixing (NOB-130, Hosokawa Micron) at 3,000 rpm to prepare a cathode active material composite in which a Br-containing sulfide solid electrolyte coating layer was formed on the LiNbO3-coated cathode active material. In the cathode active material composite, the cathode active material was 98.5 wt%, LiNbO3 was 0.5 wt%, and the Br-containing sulfide solid electrolyte was 1 wt%.

[0226] <Example 2>

[0227] In Example 1, a cathode active material composite was prepared in the same manner as in Example 1, except that Li2ZrO3 was used instead of LiNbO3.

[0228] <Example 3>

[0229] In Example 1, a positive electrode active material composite was prepared in the same manner as in Example 1, except that LiBO2 was used instead of LiNbO3.

[0230] <Comparative Example 1>

[0231] Average particle size (D 50 LiNi as a positive electrode active material with a thickness of 4 µm 0.8 Co 0.1 Mn 0.1 O2 was prepared and LiBO2 was coated on the surface of the positive active material to obtain a positive active material coated with LiBO2.

[0232] Next, an LPSCl azirodite-based sulfide solid electrolyte (Li6PS5Cl) was mixed with the LiBO2-coated cathode active material and mixed for 1 minute at 5,000 rpm using a Lab Blender (Waring). Then, the mixture was subjected to high-shear mixing (NOB-130, Hosokawa Micron) at 3,000 rpm to prepare a cathode active material composite in which an LPSCl azirodite-based sulfide solid electrolyte coating layer was formed on the LiBO2-coated cathode active material. In the cathode active material composite, the cathode active material was 98.5 wt%, LiBO2 was 0.5 wt%, and the LPSCl azirodite-based sulfide solid electrolyte was 1 wt%.

[0233] <Comparative Example 2>

[0234] LiNi as the positive active material 0.8 Co 0.1 Mn 0.1 O299 wt% and 1 wt% of Br-containing sulfide solid electrolyte were mixed using a Lab Blender (Waring) at 5,000 rpm for 1 minute. Next, the mixture was subjected to high-shear mixing (NOB-130, Hosokawa Micron) at 3,000 rpm to prepare a cathode active material composite in which a Br-containing sulfide solid electrolyte coating layer was formed on the cathode active material.

[0235] <Comparative Example 3>

[0236] LiNi as the positive active material 0.8 Co 0.1 Mn 0.1 O299.5 wt% was prepared and LiBO20.5 wt% was coated on the surface of the positive active material to obtain an average particle size (D 50 A cathode active material composite coated with LiBO2 having a thickness of 4 μm was obtained.

[0237] <Comparative Example 4>

[0238] In Comparative Example 3, a cathode active material composite coated with LiNbO3 was obtained in the same manner as in Comparative Example 3, except that LiNbO3 was used instead of LiBO2.

[0239]

[0240] <Experimental Example 1>

[0241] anode

[0242] 80 wt% of the cathode active material composite prepared in Examples 1 to 3 and Comparative Examples 1 to 4, 1 wt% of carbon nanofiber (CNF) conductive material, 1 wt% of polytetrafluoroethylene (PTFE), and 18 wt% of Li6PS5Cl azirodite sulfide solid electrolyte were mixed and then molded into a sheet to prepare a cathode sheet. Subsequently, the cathode sheet was laminated onto an aluminum foil with a thickness of 18 μm to prepare a total of 7 dry cathodes.

[0243] cathode

[0244] 6g of amorphous carbon (carbon black), 2g of Ag particles, 9.33g of PVdF binder (solid content 6%), and 7.67g of NMP solution were placed in a Thinky mixer container and mixed 12 times for 3 minutes at 2,000 rpm. Afterwards, 5g of NMP solution was added and mixed 5 times for 3 minutes at 2,000 rpm to prepare a cathode active material slurry, which was then coated onto a 10 μm SUS foil and dried at 100°C for 10 hours to produce a cathode.

[0245] solid electrolyte layer

[0246] A solid electrolyte layer slurry was prepared by dispersing and stirring azirodite (Li6PS5Cl) as a solid electrolyte and polytetrafluoroethylene as a binder in an anisole at a weight ratio of 95:5. This was coated onto a polyethylene terephthalate release film and vacuum dried at 100°C for 12 hours to prepare a solid electrolyte layer.

[0247] All-solid-state battery

[0248] Each all-solid-state battery was manufactured by sequentially stacking the respective anode, solid electrolyte layer, and cathode prepared above.

[0249]

[0250] For all-solid-state batteries using the positive active material composites of Examples 1 to 3 and Comparative Examples 1 to 4, a driving pressure of 10 MPa was applied, and the batteries were charged at 60°C under CC / CV, 0.1C conditions at 4.2V and 0.05C cut conditions, then activated by discharging to 3.0V under CC, 0.1C conditions, and then charged and discharged again under the same conditions. The voltage curves according to capacity are shown in FIGS. 1 to 7, respectively.

[0251] Next, the results of measuring the capacity retention rate, which is calculated by dividing the charge / discharge capacity measured through a charging / discharging protocol at 0.33C, 0.5C, 1C, and 0.1C by the charge / discharge capacity at 0.1C, are shown in Figures 8 to 14 below.

[0252] The ratio of charge / discharge capacity at 0.33C, 0.5C, and 1C to the charge / discharge capacity at 0.1C (retention(%)) was evaluated, and the results are shown in Table 1 below.

[0253] Classification Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Retention(%) 0.33 C 10 2.19 9.19 8.99 8.69 6.49 8.69 8.90.5 C 10 1.59 8.69 8.09 7.29 4.29 6.79 7.81.0 C 99 4.9 6.79 4.49 0.88 9.48 4.79 4.2 Specific capacity(mAh / g)0.33C192.7190.7191.3191.5197.3197.6200.30.5C191.718 9.7189.7188.9193.0193.9198.21.0C188.0186.1182.7176.4183.6169.8190.7

[0254]

[0255] <Experimental Example 2>

[0256] Figure 15 shows the results of measuring the thickness of the sulfide solid electrolyte coating layer on the cathode active material composite prepared in Example 2 through SEM / EDS line scanning analysis. According to Figure 15, it was confirmed that the thickness of the sulfide solid electrolyte coating layer is approximately 200 nm.

[0257]

[0258] <Experimental Example 3>

[0259] Figure 16 shows the results of measuring the area of ​​the sulfide solid electrolyte coating layer using an image program (Image J) through SEM / EDS analysis of the cathode active material composite prepared in Example 2. According to Figure 16, it was confirmed that the sulfide solid electrolyte coating layer is coated on an area of ​​20% to 25% of the total surface area of ​​the cathode active material.

[0260]

[0261] <Experimental Example 4>

[0262] Figure 17 shows the results of analyzing the Li 1s peak through XPS analysis of the cathode active material composite prepared in Example 2. The XPS analysis conditions were as follows, and the analysis results confirmed that Li of the cathode active material, rather than Li of the coating layer, was detected starting from an etching time of 4000 s.

[0263] · Equipment used: NEXSA, Thermo Fisher Scientific (ESCA-05)

[0264] · Sample preparation: The cathode active material composite powder was attached to carbon tape in a glove box, secured in a sample holder, and loaded into the XPS equipment.

[0265] · Measurement conditions

[0266] - X-ray source: Monochromated Al Kα (1486.6 eV)

[0267] - X-ray spot size: 300 µm

[0268] - Etching conditions (sputtering gun): monatomic Ar (energy: 1000 eV, current: low, raster width: 2 mm), 0.13 nm / s etching rate (based on Ta2O5)

[0269] - Charge compensation (flood gun): 0.1 V, 150 ㎂

[0270] - Survey spectrum: Scanned mode, pass energy 200 eV, energy step 1 eV

[0271] - Narrow spectrum: Scanned mode, pass energy 50 eV, energy step 0.1 eV

[0272]

[0273] <Experimental Example 5>

[0274] Figure 18 shows the results of XRD analysis performed on i) the positive active material (NCM), ii) the Br-containing sulfide solid electrolyte (SE), iii) the mixture of the two before the formation of the coating layer (before coating), and iv) the positive active material composite after the formation of the coating layer (after coating) in Example 2. According to Figure 18, it was confirmed that the coating layer is amorphous by confirming that no diffraction peaks attributable to the crystallinity of the Br-containing sulfide solid electrolyte (SE) were detected in the positive active material composite after the formation of the coating layer (after coating).

[0275]

[0276] <Experimental Example 6>

[0277] A cathode active material composite was prepared in the same manner as in Example 2, except that the process conditions in Example 2 were adjusted to form a Br-containing sulfide-based solid electrolyte on 90% of the total surface area of ​​the cathode active material coated with Li2ZrO3.

[0278] Next, after manufacturing an all-solid-state battery as in Experimental Example 1, a driving pressure of 10 MPa was applied, and the battery was charged at 60°C under CC / CV and 0.1C conditions to 4.2V and 0.05C cut conditions, then activated by discharging to 3.0V under CC and 0.1C conditions, and then the charge / discharge capacity measured through a protocol of charging and discharging at 0.33C, 0.5C, 1C, and 0.1C was divided by the charge / discharge capacity at 0.1C. The results are shown in FIG. 19.

Claims

1. Anode active material; and A coating layer provided on at least a portion of the surface of the above-mentioned positive active material; As a positive electrode active material complex comprising, The above coating layer is an anode active material composite comprising a Br-containing sulfide solid electrolyte and an oxide.

2. In Paragraph 1, The above oxide comprises an oxide selected from one or more of lithium (Li), niobium (Nb), zirconium (Zr), tungsten (W), boron (B), and titanium (Ti), forming a cathode active material composite.

3. In Paragraph 1, The above oxides are lithium niobate, lithium titanate, lithium zirconium oxide, lithium tungsten oxide, lithium borate, crystalline oxide, amorphous oxide, lithium oxide, titanium dioxide (TiO₂). b , 0 <b<5), 지르코늄 옥사이드, 텅스텐 옥사이드, 보론 옥사이드 및 이들의 혼합물로 이루어진 군에서 선택되는 하나 이상을 포함하는, 양극 활물질 복합체.

4. In Paragraph 1, The above Br-containing sulfide solid electrolyte is a cathode active material complex comprising a Br-containing sulfide solid electrolyte represented by the following chemical formula 1: [Chemical Formula 1] Li a PS b X c Br d In the above chemical formula 1, X is at least one selected from F, Cl, and I, and 5≤a≤6, 4≤b≤5, 0 <c≤1, 0<d≤1 이다.

5. In Paragraph 1, The above coating layer is an amorphous anode active material composite.

6. In Paragraph 1, The coating layer comprises a first layer provided on at least a portion of the surface of the positive electrode active material; and It includes a second layer provided on at least a portion of the surface of the positive active material or the surface of the first layer, and A positive electrode active material composite, wherein the first layer comprises the oxide and the second layer comprises the Br-containing sulfide solid electrolyte.

7. In Paragraph 1, A cathode active material composite comprising the above Br-containing sulfide solid electrolyte in an amount of 0.1 parts by weight or more to 5 parts by weight or less based on 100 parts by weight of the above cathode active material.

8. In Paragraph 1, Average particle size (D) of the above Br-containing sulfide solid electrolyte 50 The average particle size (D) of the above positive active material relative to ) 50 A positive electrode active material composite having a ratio of ) of 1.3 or more to 1000 or less.

9. In Paragraph 1, Average particle size (D) of the above Br-containing sulfide solid electrolyte 50 A positive electrode active material composite having a thickness of 0.01 μm or more to 1.5 μm or less.

10. In Paragraph 1, Average particle size (D of the above positive active material) 50 A positive electrode active material composite having a thickness of 2 μm or more to 10 μm or less.

11. In Paragraph 6, The thickness of the first layer is 1 nm or more to 100 nm or less, and A positive active material composite having a second layer thickness of 10 nm or more to 10 μm or less.

12. Anode active material complex according to any one of claims 1 to 11; Solid electrolyte; Challenge material; and An anode containing a binder.

13. A secondary battery comprising the positive electrode of paragraph 12.

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