Cathode for a solid-state battery and method for producing the same.

Abstract

Cathode (100) for a solid-state battery and method of manufacturing the same, wherein the cathode (100) comprises a composite-coated or double-coated cathode active material.

Description

Technical field

[0001] The present invention / disclosure relates to a cathode for a solid-state battery (e.g., a solid-state battery, e.g., a solid-state storage battery) comprising a composite-coated or double-coated cathode active material (e.g., a composite-coated or double-coated cathode active material), and a method for producing the same. background

[0002] Sulfide-based solid electrolytes (e.g., sulfide-based solid electrolytes, e.g., sulfide-based solid electrolytes) have recently emerged as the most promising electrolytes for solid-state batteries because they exhibit excellent lithium-ion conductivity and form good connections (e.g., good contact) with active materials (e.g., active materials) even without heat treatment.

[0003] However, sulfide-based solid electrolytes are very reactive and cause a side reaction with a cathode active material (e.g., a cathode active material, a cathode active material) which is an oxide, forming an unnecessary boundary layer (e.g., interface) and deteriorating (e.g., negatively affecting) the electrochemical properties of the solid-state battery.

[0004] In related art, a method for coating the surface of the cathode active material with a durable (e.g., solid, e.g., stable) material / substance has been described. By coating the surface of the cathode active material to prevent direct contact of the cathode active material with the sulfide-based solid electrolyte, the occurrence of a side reaction between the two components (e.g., constituents) can be prevented.

[0005] The material / substance used to coat the surface (e.g., the area) of the cathode active material for an all-solid-state battery (e.g., a solid-state battery, e.g., a solid-state accumulator) must exhibit lithium-ion conductivity and low reactivity (e.g., reactivity) with the sulfide-based solid electrolyte. Furthermore, the electronic conductivity of the material must be as low as possible to prevent decomposition / decomposition of the sulfide-based solid electrolyte by exchanging electrons with the cathode active material (e.g., the cathode active material).

[0006] Currently, useful coating materials / substances for cathode active materials for solid-state batteries include Li 2 ZrO 3 , LiNbO 3 , LiTaO 3and the like. To coat the cathode active material thinly and uniformly, an alkoxide-based precursor (e.g., an alkoxide-based precursor) that exhibits good wettability with the cathode active material must be used. However, alkoxide-based precursors (e.g., precursor materials) containing elements such as zirconium, niobium, tantalum, etc., are very expensive and may not be suitable for mass production. Explanation of the invention

[0007] In preferred aspects, the present invention / disclosure provides a cathode for a solid-state battery (e.g., a solid-state battery, e.g., a solid-state storage battery) comprising a cathode active material (e.g., a cathode active material) having a thin and uniform coating layer (e.g., coating), and a method for coating a cathode active material using a low-cost precursor material (e.g., precursor material, e.g., precursor material).

[0008] The term “solid-state battery” as used herein refers to a rechargeable secondary battery / accumulator having a solid-state electrolyte (e.g., solid state) that transfers ions between the electrodes of the battery.

[0009] In one aspect, a cathode for an all-solid-state battery is provided. The cathode comprises one or more composite particles (e.g., composite particles, composite particles) and a sulfide-based solid electrolyte. In particular, the composite particle may comprise a core part (e.g., a core portion, e.g., a core section, e.g., a main part) comprising a cathode active material (e.g., a cathode active material, e.g., a cathode active material), and a shell part (e.g., a shell part, e.g., a shell section, e.g., a shell part) coated / applied on the core part. The shell part may comprise: a first material represented by the following chemical formula 1 and a second material represented by the following chemical formula 2: Li 2+x B x O 3 [Chemical Formula 1] where x 0 <x≤1 ist, Li 2+y Py O 4 [Chemical Formula 2] where y 0 <y≤1 ist.

[0010] In certain embodiments, the cathode active material may comprise a substance (e.g., a chemical compound, e.g., a composition) represented by the chemical formula 3 below. [Chemical Formula 3] Li x M1 a M2 b M3 c O y

[0011] In chemical formula 3, each of M1, M2 and M3 is independently selected from the group consisting of Ni, Co, Mn, Na, Mg, Ca, Ti, V, Cr, Cu, Zn, Ge, Sr, Ag, Ba, Zr, Nb, Mo, Al, Ga and B, where 0 <x≤1,1, 1,98≤y≤2,02, 0<a<1, 0<b<1, 0<c<1 und 0<a+b+c≤1.

[0012] The thickness of the shell part (e.g. the mantle part, e.g. the shell part) can be about 0.5 nm to 50 nm.

[0013] The shell part may comprise the first material / substance and the second material / substance in a mass ratio of about 1:0.25 to 1:4.

[0014] The composite particle (e.g., the composite particle, e.g., the composite particles) may have an amount of about 97 wt.% to 99.99 wt.% of the core portion (e.g., the core portion, e.g., the main portion) and an amount of about 0.01 wt.% to 3 wt.% of the shell portion, based on the total weight of the composite particle.

[0015] The shell part (e.g. the shell part, e.g. the jacket part) may comprise a first shell (e.g. a first shell, e.g. a first jacket) arranged on / at the core part and comprising the first material / substance, and a second shell (e.g. a second shell, e.g. a second jacket) arranged on / at the first shell and comprising the second material / substance.

[0016] The shell portion may comprise the first shell and the second shell in a mass ratio of about 1:0.25 to 1:4.

[0017] In one aspect, a method for producing a cathode for a solid-state battery is provided, comprising: preparing a first (chemical) solution comprising a lithium precursor (e.g., a lithium precursor), a boron precursor (e.g., a boron precursor), and a phosphorus precursor (e.g., a phosphorus precursor); obtaining a second solution by adding a core portion comprising a cathode active material to the first solution; obtaining an intermediate product in a powder form by drying the second solution; obtaining a composite particle by heat-treating the intermediate product in (e.g., under) an oxygen atmosphere; and producing a cathode comprising the composite particles and a sulfide-based solid electrolyte.

[0018] The lithium precursor may comprise lithium ethoxide.

[0019] The boron precursor may contain boric acid.

[0020] The phosphorus precursor substance can, for example, comprise polyphosphoric acid.

[0021] In a further aspect, a method for producing a cathode for a solid-state battery is provided. The method comprises the following steps: preparing a first (chemical) solution comprising a lithium precursor and a boron precursor, obtaining a second solution by adding a core part (e.g., a core portion, e.g., a main portion) comprising a cathode active material to the first solution, obtaining a first intermediate product in a powder form by drying the second solution, obtaining a first composite particle comprising the core part and a first shell (e.g., a first shell, e.g., a first cladding) arranged on / at the core part and comprising a first material represented by the chemical formula 1, by heat-treating the first intermediate product in (e.g.,under) an oxygen atmosphere, preparing a third solution comprising a lithium precursor and a phosphorus precursor, obtaining a fourth solution by adding the first composite particle to the third solution, obtaining a second intermediate product in a powder form by drying the fourth solution, obtaining a second composite particle comprising the first composite particle and a second shell (e.g., a second shell, e.g., a second cladding) disposed on / at the first shell and comprising a second material represented by chemical formula 2, by heat-treating the second intermediate product in an oxygen atmosphere, and producing a cathode comprising the second composite particle and a sulfide-based solid electrolyte.

[0022] Furthermore, a solid-state battery is provided which has the cathode described here.

[0023] Also provided is a vehicle having the solid state battery described herein.

[0024] Other aspects of the invention are disclosed below. Short description of the drawings

[0025] The above and other features of the present invention / disclosure will now be described in detail with reference to certain exemplary embodiments thereof illustrated in the accompanying drawings, which are given below for illustrative purposes only and thus are not limitative of the present invention / disclosure, in which: Fig. 1 shows an exemplary solid-state battery according to an exemplary embodiment of the present invention / disclosure, Fig. 2 shows an exemplary composite particle according to an exemplary embodiment of the present invention / disclosure, Fig.3 shows an exemplary composite particle according to an exemplary embodiment of the present invention / disclosure, Fig. 4 shows a scanning electron microscope image of the cathode active material used in Example 1, Fig. 5 shows a scanning electron microscope image of the composite particle from Example 1, Fig. 6 shows a scanning electron microscope image of the second composite particle from Example 2, Fig. Figure 7 shows a transmission electron microscope image of the cathode active material used in Example 1, Fig. 8 shows a transmission electron microscope image of the composite particle from Example 1, Fig. 9 shows a transmission electron microscope image of the second composite particle from Example 2, Fig.10 shows initial charge / discharge curves of solid-state batteries having cathodes containing composite particles according to Examples 1 and 2 and Comparative Examples 1 to 3, Fig. 11 shows results of measuring capacity changes during charging and discharging of the all-solid-state batteries having cathodes containing composite particles according to Examples 1 and 2 and Comparative Examples 1 to 3, Fig. 12 shows initial charge / discharge curves of solid-state batteries having cathodes comprising composite particles according to Examples 1 and 3 to 6 and Comparative Example 1, Fig. 13 shows the results of measuring the capacity changes during charging and discharging of the all-solid-state batteries having cathodes containing composite particles according to Examples 1 and 3 to 6 and Comparative Example 1, Fig.14 shows a Nyquist diagram of the composite particles according to Comparative Example 1, Fig. 15 shows a Nyquist diagram of the composite particles according to Example 7, and Fig. 16 shows a Nyquist diagram of the composite particles according to Example 4. Detailed description

[0026] The above and other objects, features, and advantages of the present invention / disclosure will become more apparent from the following preferred embodiments taken in conjunction with the accompanying drawings. However, the present invention / disclosure is not limited to the embodiments disclosed herein and may be modified in various forms. These embodiments are provided to fully explain the invention / disclosure and to sufficiently convey the teachings of the present disclosure to those skilled in the art.

[0027] In the drawings, the same reference numerals refer to the same or similar elements throughout. For clarity of the present invention / disclosure, the dimensions of the structures are shown larger than their actual sizes. It is to be understood that although terms such as "first," "second," etc., may be used herein to describe various elements, these elements are not limited by these terms. These terms are used only to distinguish one element from another element. For example, a "first" element described below could be referred to as a "second" element without departing from the scope of the present invention / disclosure. Likewise, the "second" element could also be referred to as a "first" element.The singular forms used herein shall be construed to include the plural forms as well, unless the context indicates otherwise.

[0028] It is further to be understood that the terms "comprise," "comprising," "having," etc., when used in this description, specify the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, but do not preclude / prevent the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof. Furthermore, it is to be understood that when an element such as a layer, film, region, or sheet is referred to as being "on top of" another element, it may be directly on top of the other element, or there may be intervening elements in between. When an element such as a layer, film, region, or sheet is referred to as being "under" another element, it may be directly under the other element, or there may be intervening elements in between.

[0029] Unless otherwise stated, all numbers, values, and / or representations expressing the number / amounts of ingredients / components, reaction conditions, polymer compositions, and blends used herein are approximate, including various measurement uncertainties inherent in obtaining these values, and should therefore be understood as being modified in all cases by the term "about." Unless specifically stated or evident from the context, the term "about" as used herein is understood to be within a range of normal tolerances in the art, e.g., within 2 standard deviations of the mean. "About" may be understood to mean within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value.Unless the context indicates otherwise, all numerical values ​​stated herein are modified by the term “about.”

[0030] Furthermore, if a numerical range is disclosed in this specification, this range is continuous and includes all values ​​from the minimum value of the range to the maximum value of the range, unless otherwise specified. Furthermore, if such a range refers to integer values, all integers including the minimum value up to the maximum value are included, unless otherwise specified. When a range is described for a variable in this specification, it is understood that the variable includes all values, including the described endpoints, within the specified range. For example, the range "5 to 10" includes all subranges, such as 6 to 10, 7 to 10, 6 to 9, 7 to 9, and the like, as well as individual values ​​of 5, 6, 7, 8, 9, and 10, and also includes any value between valid integers within the specified range, such as 5.5, 6.5, 7.5, 5.5 to 8.5, 6.5 to 9, and the like.For example, the range "10% to 30%" includes subranges such as 10% to 15%, 12% to 18%, 20% to 30%, etc., as well as all integers including / including the values ​​10%, 11%, 12%, 13%, and the like up to 30%, and also includes any value between valid integers within the specified range, such as 10.5%, 15.5%, 25.5%, and the like.

[0031] It should be understood that the term "vehicle" or "vehicular" or other similar terms, as used herein, includes motor vehicles in general, such as passenger cars, including sport utility vehicles (SUVs), buses, trucks, various commercial vehicles, watercraft, including a variety of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles, and other vehicles powered by alternative fuels (e.g., fuels derived from resources other than petroleum). As noted herein, a hybrid vehicle is a vehicle that has two or more power sources, e.g., both gasoline-powered and electric-powered vehicles.

[0032] Fig.1 shows an exemplary solid-state battery according to an exemplary embodiment of the present invention / disclosure. The solid-state battery (e.g., the solid-state battery, e.g., the solid-state accumulator) may include a cathode 100, an anode 200, and a solid electrolyte layer 300 disposed between the cathode 100 and the anode 200.

[0033] The cathode 100 may include a composite particle (e.g., a composite particle), a sulfide-based solid electrolyte (e.g., a sulfide-based solid electrolyte, e.g., a sulfide-based solid electrolyte), a conductive material, a binder (e.g., a binder), and the like.

[0034] Fig.2 shows an exemplary composite particle 10 according to a first embodiment of the present invention / disclosure. The composite particle 10 may include: a core portion 11 (e.g., a core portion, e.g., a main portion, e.g., a core section) comprising a cathode active material (e.g., a cathode active material, a cathode active material), and a shell portion 12 (e.g., a shell portion, e.g., a jacket portion, e.g., a shell section) applied or coated onto the core portion 11.

[0035] The core part 11 may suitably comprise a cathode active material which is formed by means of Li x M1 a M2 b M3 c O y (in which each of M1, M2 and M3 is independently selected from the group consisting of Ni, Co, Mn, Na, Mg, Ca, Ti, V, Cr, Cu, Zn, Ge, Sr, Ag, Ba, Zr, Nb, Mo, Al, Ga and B, with 0 <x≤1,1,1,98≤y≤2,02, 0<a<1, 0<b<1, 0<c<1, und 0<a+b+c≤1).

[0036] The average particle diameter of the cathode active material is not particularly limited and can be, for example, between 3 µm and 25 µm.

[0037] The shell part 12 (e.g., the shell part, e.g., the jacket part) may comprise a first material represented by the following chemical formula 1 and a second material represented by the following chemical formula 2: Li 2+x B x O 3 , [Chemical Formula 1] where x 0 <x≤1 sein kann, und Li 2+y P y O 4 [Chemical Formula 2] where y 0 <y≤1 sein kann.

[0038] The first material / substance can be suitably Li 3 BO 3 The second material / substance can be suitably Li 3 PO 4 have.

[0039] Since the first material has a strong BO covalent bond (e.g., a strong BO atomic bond, e.g., a strong BO covalent bond), its reactivity (e.g., its reactivity) towards a sulfide-based solid electrolyte is low.

[0040] The second material is also chemically stable because it has a strong PO covalent bond (e.g., a strong PO atom bond, e.g., a strong covalent PO bond). Since the second material also has O 2- , which is an anion that is also present in the cathode active material, and P 5+, which is a cation that is also present in the sulfide-based solid electrolyte, interdiffusion (e.g., solid-state diffusion) of sulfur (S) ions and phosphorus (P) ions of the sulfide-based solid electrolyte and transition metal ions and oxygen (O) ions of the cathode active material can be prevented. The interdiffusion (e.g., solid-state diffusion) between the cathode active material and the sulfide-based solid electrolyte is caused by the binding of oxygen (O) in the cathode active material and phosphorus (P) in the sulfide-based solid electrolyte. The second material already has a PO 4- bond and is therefore able to prevent a side reaction between the cathode active material and the sulfide-based solid electrolyte.

[0041] The thickness of the shell portion 12 may be approximately 0.5 nm to 50 nm. If the thickness of the shell portion 12 is greater than approximately 50 nm, an internal resistance of the cathode 100 may increase and battery performance may deteriorate.

[0042] The shell part 12 (e.g., the shell part, e.g., the jacket part) may comprise the first material and the second material in a mass ratio of approximately 1:0.25 to 1:4. When the mass ratio of the first material to the second material falls within the above-mentioned numerical range, the side reaction between the cathode active material and the sulfide-based solid electrolyte can be suppressed, thereby improving battery performance.

[0043] The composite particle 10 (e.g., the composite particle) may comprise an amount of about 97 to 99.99 wt.% of the core portion 11 and / or an amount of about 0.01 to 3 wt.% of the shell portion 12, wherein the wt.% is based on the total weight of the composite particle. If the proportion of the shell portion 12 is greater than about 3 wt.%, the internal resistance of the cathode 100 may increase, and battery performance may deteriorate.

[0044] A method for manufacturing a cathode comprising the composite particle 10 of the first embodiment may include: preparing a first (chemical) solution comprising a lithium precursor (e.g., a lithium precursor), a boron precursor (e.g., a boron precursor), and a phosphorus precursor (e.g., a phosphorus precursor); obtaining a second solution by adding a core portion comprising a cathode active material to the first solution; obtaining an intermediate product in a powder form by drying the second solution; obtaining the composite particle by heat-treating the intermediate product in (e.g., under) an oxygen atmosphere; and manufacturing a cathode comprising the composite particle and a sulfide-based solid electrolyte.

[0045] The lithium precursor may suitably comprise lithium ethoxide. The boron precursor may suitably comprise boric acid. The phosphorus precursor may suitably comprise polyphosphoric acid. The boric acid is a precursor of the first material / material, and the polyphosphoric acid is a precursor of the second material / material. Since both boric acid and polyphosphoric acid are inexpensive, a thin and uniform shell part (e.g., shell part, e.g., mantle part) can be manufactured using inexpensive materials according to the present invention / disclosure.

[0046] The amounts (e.g., the proportions, e.g., the concentrations) of the lithium precursor, the boron precursor, and the phosphorus precursor in the first solution are not particularly limited, and the respective precursors can be appropriately weighed and prepared depending on the desired composition of the first material and the second material.

[0047] The first solution can be prepared by dissolving / decomposing the lithium precursor, the boron precursor, and the phosphorus precursor in a solvent. Any solvent can be used as long as it is capable of dissolving (e.g., decomposing) the lithium precursor, the boron precursor, and the phosphorus precursor, and an example of this can include an alcohol-based solvent (e.g., an alcohol-based solvent).

[0048] The second solution can be obtained by adding the core part (eg, the core portion, eg, the main part) comprising a cathode active material to the first solution, and the intermediate product in a powder form can be obtained by drying the second solution to remove the solvent.

[0049] Drying can be performed using any device or method as long as the solvent can be completely removed. For example, the second solution can be dried with stirring at about 40°C to 100°C for about 1 hour to 10 hours. Vacuum drying of the intermediate product at about 70°C to 150°C for about 1 hour to 6 hours can also be performed to completely remove the residual solvent.

[0050] The composite particle 10 can be prepared by heat treating the intermediate product at about 200°C to 500°C for about 1 hour to 5 hours in (e.g., under) an oxygen atmosphere to cause / induce a reaction between the lithium precursor (e.g., the lithium precursor), the boron precursor (e.g., the boron precursor), and the phosphorus precursor (e.g., the phosphorus precursor).

[0051] The method for manufacturing the cathode is not particularly limited and can be performed in a dry or wet manner (e.g., dry or wet). For example, a cathode can be manufactured by coating a substrate (e.g., a support material, e.g., a coating substrate) with a slurry (e.g., a fine slurry) comprising the composite particle 10, a sulfide-based solid electrolyte (e.g., a sulfide-based solid electrolyte), a conductive material, and a binder (e.g., a binder), and then drying.

[0052] Fig.3 shows an exemplary composite particle 10' according to a second embodiment of the present invention / disclosure. The composite particle 10' may include a core portion 11' comprising a cathode active material, and a shell portion 12' applied or coated on the core portion 11'. The shell portion 12' may include a first shell 121 (e.g., a first shell, e.g., a first cladding) disposed on the core portion 11' and comprising a first material represented by the following chemical formula 1, and a second shell 122 (e.g., a second shell, e.g., a second cladding) disposed on the first shell 121 and comprising a second material represented by the following chemical formula 2: Li 2+x B x O 3 [Chemical Formula 1] where x 0 <x≤1 sein kann, und Li 2+y P y O 4 [Chemical Formula 2] where y 0 <y≤1 sein kann.

[0053] The first material / substance can be suitably Li 3 BO 3 The second material / substance can be suitably Li 3 PO 4 have.

[0054] The shell part 12' may comprise the first shell 121 and the second shell 122 in a mass ratio of approximately 1:0.25 to 1:4.

[0055] Furthermore, a method for producing a cathode comprising the composite particle 10' (e.g., the composite particle) of the second embodiment is provided. The method may include: preparing a first solution comprising a lithium precursor and a boron precursor, obtaining a second solution by adding a core part comprising a cathode active material to the first solution, obtaining a first intermediate product in a powder form by drying the second solution, obtaining a first composite particle comprising the core part and a first shell arranged on / at the core part by heat-treating the first intermediate product in (e.g.,under) an oxygen atmosphere, preparing a third solution comprising a lithium precursor and a phosphorus precursor, obtaining a fourth solution by adding the first composite particle to the third solution, obtaining a second intermediate product in a powder form by drying the fourth solution, obtaining a second composite particle each comprising the first composite particle and a second shell arranged on / at the first shell by heat-treating the second intermediate product in an oxygen atmosphere, and producing a cathode comprising the second composite particle and a sulfide-based solid electrolyte.

[0056] The lithium precursor may suitably comprise lithium ethoxide. The boron precursor may suitably comprise boric acid.

[0057] The amounts of the lithium precursor and the boron precursor in the first solution are not particularly limited, and the respective precursors can be appropriately weighed and prepared depending on the desired composition of the first material / substance.

[0058] The first solution can be prepared by dissolving / decomposing the lithium precursor and the boron precursor in a solvent. Any solvent can be used here as long as it is capable of dissolving the lithium precursor and the boron precursor, and an example of this can include an alcohol-based solvent (e.g., an alcohol-based solvent).

[0059] The second solution can be obtained by adding the core part (eg, the core portion, eg, the main part) comprising a cathode active material to the first solution, and the first intermediate product in a powder form can be obtained by drying the second solution to remove the solvent.

[0060] Drying can be performed using any device or method as long as the solvent can be completely removed. For example, the second solution can be dried with stirring at about 40°C to 100°C for about 1 hour to 10 hours. Likewise, vacuum drying of the first intermediate product at about 70°C to 150°C for about 1 hour to 6 hours can be performed to completely remove the residual solvent.

[0061] The thus obtained first intermediate product may be heat-treated at about 200 °C to 500 °C for about 1 hour to 5 hours in an oxygen atmosphere to cause / induce a reaction between the lithium precursor and the boron precursor, thereby producing the first composite particle having a core part and a first shell.

[0062] The phosphorus precursor may suitably comprise polyphosphoric acid.

[0063] The amounts of the lithium precursor and the phosphorus precursor in the third solution are not particularly limited, and the respective precursors can be appropriately weighed and prepared depending on the desired composition of the second material / substance.

[0064] The third solution can be prepared by dissolving the lithium precursor and the phosphorus precursor in a solvent. Any solvent can be used as long as it is capable of dissolving the lithium precursor and the phosphorus precursor, and an example of this can include an alcohol-based solvent. This solvent can be the same as or different from the solvent present in the first solution.

[0065] The fourth solution can be obtained by adding the first composite particle to the third solution, and the second intermediate in a powder form can be obtained by drying the fourth solution to remove the solvent.

[0066] Drying can be performed using any device or method as long as the solvent can be completely removed. For example, the fourth solution can be dried with stirring at about 40°C to 100°C for about 1 hour to 10 hours. Likewise, vacuum drying of the second intermediate product at about 70°C to 150°C for about 1 hour to 6 hours can be performed to completely remove the residual solvent.

[0067] The second intermediate thus obtained may be heat-treated in (e.g., under) an oxygen atmosphere at about 200°C to 500°C for about 1 hour to 5 hours to cause / induce a reaction between the lithium precursor (e.g., the lithium precursor) and the phosphorus precursor (e.g., the phosphorus precursor), thereby producing the second composite particle(s), each configured to form the second shell on / at the first shell.

[0068] The method for manufacturing the cathode is not particularly limited and can be performed in a dry or wet manner (e.g., dry or wet). For example, a cathode can be manufactured by coating a substrate (e.g., a support material, e.g., a coating substrate) with a slurry (e.g., a fine slurry) comprising the second composite particle, a sulfide-based solid electrolyte, a conductive material, and a binder (e.g., a binder), and drying.

[0069] Examples of sulfide-based solid electrolytes may include: Li 2 SP 2 S 5 , Li 2 SP 2 S 5 -Lil, Li 2 SP 2 S 5 -LiCl, Li 2 SP 2 S 5 -LiBr, Li 2 SP 2 S 5 -Li 2 O, Li 2 SP 2 S 5 -Li 2 O-Lil, Li 2 S-SiS2 , Li 2 S-SiS 2 -Lil, Li 2 S-SiS 2 -LiBr, Li 2 S-SiS 2 -LiCl, Li 2 S-SiS 2 -B 2 S 3 -Lil, Li 2 S-SiS 2 -P 2 S 5 -Lil, Li 2 SB 2 S 3 , Li 2 SP 2 S S -Z m S n (where m and n are positive numbers and Z is any of Ge, Zn and Ga), Li 2 S-GeS 2 , Li 2 S-SiS 2 -Li 3 PO 4 , Li 2 S-SiS 2 -Li x MO y (where x and y are positive numbers and M is any of P, Si, Ge, B, Al, Ga and In), Li 10 GeP 2 S 12 , and the like.

[0070] Examples of the conductive material may include carbon black (e.g., industrial carbon black), conductive graphite, ethylene black, graphene, and the like.

[0071] Examples of the binder (e.g., the binding agent) may include butadiene rubber, nitrile butadiene rubber, hydrogenated nitrile butadiene rubber, polyvinylidene fluoride, polytetrafluoroethylene, and the like. EXAMPLES

[0072] A better understanding of the present invention / disclosure can be obtained from the following examples. These examples are merely illustrative of the present invention / disclosure and are not intended to limit the scope of the present invention / disclosure. Example 1

[0073] A composite particle comprising approximately 99.8 wt.% of a core portion and approximately 0.2 wt.% of a shell portion, based on the total weight of the composite particle, was prepared as follows. The amounts of precursors were adjusted such that the shell portion comprised approximately 0.05 wt.% of a first material and approximately 0.15 wt.% of a second material, based on the total weight of the composite particle.

[0074] A first solution was prepared by dissolving / decomposing lithium ethoxide, boric acid, and polyphosphoric acid in an alcohol-based solvent. A second solution was prepared by adding about 5 g of the core part, the LiNi 0.8 Co 0.1 Mn 0.1 O 2 as cathode active material, to about 30 ml of the first solution.

[0075] The second solution was dried with stirring at about 70 °C for about 4 hours until the solvent was completely evaporated to obtain an intermediate. The intermediate was dried under vacuum at about 90 °C for about 2 hours, completely removing the residual solvent.

[0076] The intermediate product was heat-treated at about 400 °C for about 1 hour in an oxygen atmosphere, thereby obtaining the composite particle having the core part and the shell part. Example 2

[0077] A composite particle comprising about 99.8 wt.% of a core portion and about 0.2 wt.% of a shell portion, based on the total weight of the composite particle, was prepared as follows. The shell portion was formed from a first shell comprising a first material and a second shell comprising a second material. The amounts of precursors were adjusted such that the amount of the first shell was about 0.05 wt.% and the amount of the second shell was about 0.15 wt.%, based on the total weight of the composite particle.

[0078] A first solution was prepared by dissolving lithium ethoxide and boric acid in a solvent. A second solution was prepared by adding about 5 g of the core part, the LiNi 0.8 Co 0.1 Mn 0.1 O 2 as cathode active material, to about 30 ml of the first solution.

[0079] The second solution was dried with stirring at about 70 °C for about 4 hours until the solvent was completely evaporated to obtain a first intermediate. The first intermediate was vacuum dried at about 90 °C for about 2 hours, thereby completely removing the residual solvent.

[0080] The first intermediate product was heat-treated at about 400 °C for about 1 hour in an oxygen atmosphere, thereby obtaining the first composite particle comprising the core part and the first shell.

[0081] A third solution was prepared by dissolving / decomposing lithium ethoxide and polyphosphoric acid in a solvent. A fourth solution was obtained by adding approximately 5 g of the first composite particle to approximately 30 ml of the third solution.

[0082] The fourth solution was dried with stirring at about 70 °C for about 4 hours until the solvent was completely evaporated to obtain a second intermediate. The second intermediate was vacuum dried at about 90 °C for about 2 hours, completely removing the residual solvent.

[0083] The second intermediate product was heat-treated at about 400 °C for about 1 hour in an oxygen atmosphere, thereby obtaining the second composite particle(s) comprising the core part, the first shell, and the second shell, respectively. Fig. Figure 4 shows a scanning electron microscope image of the cathode active material used in Example 1. Fig. Figure 5 shows a scanning electron microscope image of the composite particle from Example 1. Fig. Figure 6 shows a scanning electron microscope image of the second composite particle from Example 2. As shown in the Fig. 5 and Fig. As can be seen in Figure 6, no foreign matter was found on the surface of each particle and the shell part was thin and uniform. Fig. Figure 7 shows a transmission electron microscope image of the cathode active material used in Example 1. Fig. Figure 8 shows a transmission electron microscope image of the composite particle from Example 1. Fig. Figure 9 shows a transmission electron microscope image of the second composite particle from Example 2. To eliminate the influence of the lithium residues present in each sample, each sample was washed with distilled water and then examined using a transmission electron microscope. When comparing the Fig. 8 and Fig. 9 with Fig. 7 shows that a very thin and uniform shell part (e.g. shell part, e.g. mantle part) has formed on the surface of the cathode active material. Comparison example 1

[0084] A cathode active material without a shell part was set as Comparative Example 1. The same cathode active material as in Example 1 was used. Comparison example 2

[0085] A composite particle was prepared in the same manner as in Example 2, except that only the first shell was formed and the second shell was not formed. Comparison example 3

[0086] A composite particle was prepared in the same manner as in Example 2, except that the first shell was not formed and the second shell was formed on the surface of the cathode active material.

[0087] Fig. Figure 10 shows initial charge / discharge curves of all-solid-state batteries having cathodes comprising the composite particles of Examples 1 and 2 and Comparative Examples 1 to 3. Fig.Figure 11 shows results of measuring capacity changes during charging and discharging of the all-solid-state batteries having cathodes containing the composite particles of Examples 1 and 2 and Comparative Examples 1 to 3. Both Example 1 and Example 2 had better discharge capacity than Comparative Example 1 in which the shell part was not formed. Example 3

[0088] A composite particle was prepared in the same manner as in Example 1, except that the amounts of the precursors were adjusted so that the shell portion comprised about 0.05 wt% of the first material and about 0.1 wt% of the second material based on the total weight of the composite particle. Example 4

[0089] A composite particle was prepared in the same manner as in Example 1, except that the amounts of the precursors were adjusted so that the shell portion comprised about 0.1 wt% of the first material and about 0.1 wt% of the second material based on the total weight of the composite particle. Example 5

[0090] A composite particle was prepared in the same manner as in Example 1, except that the amounts of the precursors were adjusted so that the shell portion comprised about 0.1 wt% of the first material and about 0.15 wt% of the second material based on the total weight of the composite particle. Example 6

[0091] A composite particle was prepared in the same manner as in Example 1, except that the amounts of the precursors were adjusted so that the shell portion comprised about 0.15 wt% of the first material and about 0.1 wt% of the second material based on the total weight of the composite particle.

[0092] Fig. Figure 12 shows initial charge / discharge curves of all-solid-state batteries having cathodes comprising the composite particles of Examples 1 and 3 to 6 and Comparative Example 1. Fig. Figure 13 shows results of measuring capacity changes during charging and discharging of the all-solid-state batteries having cathodes containing the composite particles of Examples 1 and 3 to 6 and Comparative Example 1. Examples 1 and 3 to 6 all had higher discharge capacity compared to Comparative Example 1 in which the shell part was not formed.

[0093] The charge / discharge capacities and initial efficiencies of the all-solid-state batteries having cathodes containing the composite particles according to Examples 1 and 3 to 6, as well as Comparative Examples 1 to 3, are shown in Table 1 below. These results were measured at a discharge voltage of 4.25-2.5 vs Li+ / Li and a temperature of 30 ± 2 °C. Table 1 Classification Cover part 1) Charging capacity [mAh / g] Discharge capacity [mAh / g] Initial efficiency Comparison example 1 - 236,2 172,9 73,2 Comparison example 2 0.05 wt% of LBO 226,6 182,1 80,36 Comparison example 3 0.15 wt% of LPO 228,5 192,7 84,33 Example 1 0.05 wt% of LBO + 0.15 wt% of LPO 230,5 195,9 84,99 Example 3 0.05 wt% of LBO + 0.1 wt% of LPO 232,3 194,5 83,73 Example 4 0.1 wt% of LBO + 0.1 wt% of LPO 230,1 188,7 82,01 Example 5 0.1 wt% of LBO + 0.15 wt% of LPO 233,4 188,3 80,68 Example 6 0.15 wt% of LBO + 0.1 wt% of LPO 219,6 182,8 83,24 1) LBO denotes Li 3 BO 3 and LPO denotes Li 3 PO 4

[0094] As shown in Table 1, Examples 1 and 3 to 6 exhibited high charge / discharge capacity and high initial efficiency compared to Comparative Example 1. Example 7

[0095] A composite particle was prepared in the same manner as in Example 2, except that the amounts of the precursors were adjusted so that the amount of the first shell was about 0.1 wt% and the amount of the second shell was about 0.1 wt% based on the total weight of the composite particle.

[0096] Fig. Figure 14 shows a Nyquist diagram of the composite particle according to Comparative Example 1. Fig. Figure 15 shows a Nyquist diagram of the composite particle according to Example 7. Fig. Figure 16 shows a Nyquist diagram of the composite particle according to Example 4. The composite particles according to Examples 4 and 7 have a small semicircle size compared to Comparative Example 1, indicating that the impedance value (e.g., the apparent resistance value) of the cell (e.g., the battery cell) has been reduced. Therefore, according to the present invention / disclosure, the resistance of the cathode can be effectively lowered / decreased.

[0097] As apparent from the above description, according to various exemplary embodiments of the present invention / disclosure, a cathode for an all-solid-state battery can be obtained, which comprises a cathode active material having a thin and uniform coating layer (e.g., coating).

[0098] According to various exemplary embodiments of the present invention / disclosure, the cathode active material can be thinly and uniformly coated / applied with inexpensive precursors.

[0099] The effects of the present invention / disclosure are not limited to the above-mentioned effects / effects. The effects of the present invention / disclosure are intended to include all effects / effects that can be deduced from the description of the present invention / disclosure.

[0100] While the exemplary embodiments of the present invention / disclosure have been described in detail above, the scope of the present invention / disclosure is not limited to the above-described embodiments, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention / disclosure defined in the following claims also fall within the scope of the present invention / disclosure.

Claims

[1] Cathode (100) for a solid-state battery, comprising: a composite particle (10, 10'), and a sulfide-based solid electrolyte, wherein the composite particle (10, 10') comprises: a core part (11, 11') comprising a cathode active material, and a shell part (12, 12') coated on the core part (11, 11'), and the shell part (12, 12') comprises: a first substance represented by chemical formula 1 and a second substance represented by chemical formula 2: Li 2+x B x O 3 [Chemical Formula 1] where x 0 <x≤1 ist, und Li 2+y P y O 4 [Chemical Formula 2] where y 0 <y≤1 ist. [2] Cathode (100) according to claim 1, wherein the cathode active material comprises a compound represented by the chemical formula 3: Li x M1 a M2 bM3 c O y [Chemical Formula 3] wherein each of M1, M2 and M3 is independently selected from the group consisting of Ni, Co, Mn, Na, Mg, Ca, Ti, V, Cr, Cu, Zn, Ge, Sr, Ag, Ba, Zr, Nb, Mo, Al, Ga and B, and 0 <x≤1,1,1,98≤y≤2,02,0<a<1,0<b<1,0<c<1, und 0<a+b+c≤1. [3] The cathode (100) according to any one of claims 1 or 2, wherein a thickness of the shell part (12, 12') is about 0.5 nm to 50 nm. [4] Cathode (100) according to any one of claims 1-3, wherein the shell part (12, 12') comprises the first substance and the second substance in a mass ratio of about 1:0.25 to 1:

4. [5] The cathode (100) of any one of claims 1-4, wherein the composite particle (10, 10') comprises an amount of about 97 wt% to 99.99 wt% of the core portion (11, 11') and an amount of about 0.01 wt% to 3 wt% of the shell portion (12, 12'), based on the total weight of the composite particle (10, 10'). [6] The cathode (100) according to any one of claims 1-5, wherein the sheath part (12, 12') comprises: a first sheath (121) disposed on the core part (11) and comprising the first material, and a second sheath (122) disposed on the first sheath and comprising the second material. [7] The cathode (100) of claim 6, wherein the shell portion (12, 12') comprises the first shell (121) and the second shell (122) in a mass ratio of about 1:0.25 to 1:

4. [8] A method for producing a cathode (100) for a solid-state battery, comprising: Preparing a first solution comprising a lithium precursor, a boron precursor and a phosphorus precursor, Obtaining a second solution by adding a core part (11, 11') comprising a cathode active material to the first solution, Obtaining an intermediate product in a powder form by drying the second solution, Obtaining a composite particle (10, 10') by heat-treating the intermediate product in an oxygen atmosphere, and Producing a cathode (100) comprising the composite particle (10, 10') and a sulfide-based solid electrolyte, wherein the composite particle (10, 10') comprises the core part (11, 11') and a shell part (12, 12') coated on the core part (11, 11'), and the shell part (12, 12') comprises: a first substance represented by chemical formula 1 and a second substance represented by chemical formula 2: Li 2+x B x O 3 [Chemical Formula 1] where x 0 <x≤1 ist, und Li 2+y P y O 4 [Chemical Formula 2] where y 0 <y≤1 ist. [9] The method of claim 8, wherein the lithium precursor comprises lithium ethoxide. [10] A method according to any one of claims 8 or 9, wherein the boron precursor comprises boric acid. [11] A process according to any one of claims 8-10, wherein the phosphorus precursor comprises polyphosphoric acid. [12] A method according to any one of claims 8-11, wherein the cathode active material comprises a compound represented by the chemical formula 3: Li x M1 a M2 b M3 c O y [Chemical Formula 3] wherein each of M1, M2 and M3 is independently selected from the group consisting of Ni, Co, Mn, Na, Mg, Ca, Ti, V, Cr, Cu, Zn, Ge, Sr, Ag, Ba, Zr, Nb, Mo, Al, Ga and B; and 0 <x≤1,1,1,98≤y≤2,02,0<a<1,0<b<1,0<c<1, und 0<a+b+c≤1. [13] A method according to any one of claims 8-12, wherein the shell part (12, 12') comprises the first substance and the second substance in a mass ratio of about 1:0.25 to 1:

4. [14] The method of any one of claims 8-13, wherein the composite particle (10, 10') comprises an amount of about 97 wt% to 99.99 wt% of the core portion (11, 11') and an amount of about 0.01 wt% to 3 wt% of the shell portion (12, 12'), based on the total weight of the composite particle (10, 10'). [15] A method for producing a cathode (100) for a solid-state battery, comprising: Preparing a first solution comprising a lithium precursor and a boron precursor, Obtaining a second solution by adding a core part (11, 11') comprising a cathode active material to the first solution; Obtaining a first intermediate product in a powder form by drying the second solution, Obtaining a first composite particle (10, 10') comprising: the core part (11, 11') and a first shell (121) arranged on the core part (11, 11') and comprising a first substance represented by the chemical formula 1, by heat-treating the first intermediate product in an oxygen atmosphere: Li 2+x B x O 3 [Chemical Formula 1] where x 0 <x≤1 ist, Preparing a third solution comprising a lithium precursor and a phosphorus precursor; Obtaining a fourth solution by adding the first composite particle (10, 10') to the third solution; Obtaining a second intermediate in a powder form by drying the fourth solution; Obtaining a second composite particle (10, 10') comprising: the first composite particle (10, 10') and a second shell (122) arranged on the first shell (121) and comprising a second substance represented by the chemical formula 2, by heat-treating the second intermediate in an oxygen atmosphere: Li 2+y P y O 4 [Chemical Formula 2] where y 0 <y≤1 ist, und herstellen einer kathode (100), die das zweite kompositpartikel (10, 10') einen sulfid-basierten feststoffelektrolyt aufweist.[16] The method of claim 15, wherein the lithium precursor comprises lithium ethoxide. [17] A method according to any one of claims 15 or 16, wherein the boron precursor comprises boric acid. [18] A process according to any one of claims 15-17, wherein the phosphorus precursor comprises polyphosphoric acid. [19] The method of any one of claims 15-18, wherein a mass ratio of the first shell (121) to the second shell (122) is about 1:0.25 to 1:

4. [20] The method of any one of claims 15-19, wherein the second composite particle (10, 10') comprises an amount of about 97 wt% to 99.99 wt% of the core portion (11, 11') and an amount of about 0.01 wt% to 3 wt% of the first shell (121) and the second shell (122), based on the total weight of the composite particle (10, 10').