Positive electrode and all-solid-state battery including same

Abstract

The present invention relates to a positive electrode and an all-solid-state secondary battery including same, the positive electrode including a sulfide-based solid electrolyte and a sulfur-containing additive that is glass or glass-ceramic and that exhibits an endothermic peak at 180°C to 220°C in differential scanning calorimetry (DSC) analysis.

Description

Anode and all-solid-state battery including the same

[0001] This relates to a positive electrode and an all-solid-state secondary battery containing the same.

[0002] Lithium-ion batteries, which offer high energy density and portability, are primarily used as the power source for mobile information terminals such as mobile phones, laptops, and smartphones. Recently, active research is being conducted to utilize high-energy-density lithium-ion batteries as power sources for driving or energy storage in hybrid and electric vehicles.

[0003] As such, batteries composed entirely of solid materials, particularly all-solid-state batteries using solid electrolytes, are being proposed. Since the electrolyte in an all-solid-state battery is solid, it is structurally rigid, resulting in a low risk of fire or explosion caused by leakage from external impacts. Additionally, the battery can be formed in various shapes.

[0004] One embodiment provides an anode with excellent safety.

[0005] Another embodiment provides an all-solid-state secondary battery comprising the above-mentioned positive electrode.

[0006] One embodiment provides an anode comprising a sulfide-based solid electrolyte; and a sulfur-containing additive which is glass or glass-ceramic and has an endothermic peak appearing at 180°C to 220°C during differential scanning thermal analysis (DSC).

[0007] Another embodiment provides an all-solid-state secondary battery comprising the anode; a cathode; and a solid electrolyte layer located between the anode and the cathode.

[0008] A positive electrode for an all-solid-state secondary battery according to one embodiment can suppress the exothermic reaction and ignition that occur during charging and discharging of a battery including the same, and can delay the exothermic reaction, thereby improving the safety of the battery.

[0009] FIG. 1 is a cross-sectional view schematically showing an all-solid-state battery according to one embodiment.

[0010] FIG. 2 is a cross-sectional view schematically showing an all-solid-state battery according to another embodiment.

[0011] Figure 3 is a differential gravimetric analysis (DSC) measurement graph of the mixture of Li6PS5Cl solid electrolyte and 75Li2S-25P2S5 additive (glass) used in Example 1.

[0012] Figure 4 is a DSC measurement graph of the anode prepared according to Example 1 and Example 2.

[0013] FIG. 5 shows the Li6PS5Cl solid electrolyte of Comparative Example 1, the Li6PS5Cl solid electrolyte used in Comparative Example 3, and Li 5.5 PS 4.5 Cl 0.75 Br 0.75 DSC measurement graph of a mixture of (crystalline) additives.

[0014] Figure 6 is a DSC measurement graph of the anode prepared according to Comparative Examples 1 and 3.

[0015] FIG. 7 shows the 75Li2S-25P2S5 additive (glass) of Comparative Example 2 and the Li of Comparative Example 4. 5.5 PS 4.5 Cl 0.75 Br 0.75 DSC measurement graph of.

[0016] Figure 8 is an X-ray diffraction measurement graph of the additives used in Example 1 and Comparative Example 3.

[0017] Hereinafter, embodiments of the present invention will be described in detail. However, these are presented as examples and are not intended to limit the present invention, and the present invention is defined only by the scope of the claims set forth below.

[0018] The terms used herein are for describing exemplary embodiments only and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise.

[0019] "Combinations of these" refers to mixtures of components, laminates, composites, copolymers, alloys, blends, reaction products, etc.

[0020] Terms such as "include," "equip," or "have" are intended to specify the existence of the implemented features, numbers, steps, components, or combinations thereof, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0021] Throughout 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.

[0022] Additionally, terms such as “about,” “substantially,” as used throughout this specification, are used to mean at or near the stated value when inherent manufacturing and material tolerances are presented in the stated meaning, and are used to prevent unscrupulous infringers from unfairly exploiting the disclosure in which precise or absolute values ​​are mentioned to aid in understanding this invention.

[0023] Throughout this specification, the description “A and / or B” means “A or B or both.”

[0024] Unless otherwise specifically stated in this specification, when a part such as a layer, film, region, plate, etc. is described as being "on" another part, this includes not only cases where it is "immediately on" another part, but also cases where there is another part in between.

[0025] In the present invention, "particle size" or "particle diameter" may be the average particle diameter. Additionally, the average particle diameter may be defined as the average particle diameter (D50) at 50% of the cumulative volume in the cumulative size-distribution curve. The particle diameter may be measured by methods widely known to those skilled in the art, for example, by measuring with a particle size analyzer, or by measuring with a transmission electron microscope, a scanning electron microscope, or a field emission scanning electron microscope (FE-SEM). Alternatively, the average particle diameter (D50) value may be obtained by measuring using a measuring device utilizing dynamic light scattering, performing data analysis to count the number of particles for each particle size range, and then calculating from this, or by measuring using a laser diffraction method. When measuring the average particle size by laser diffraction, more specifically, the particles to be measured are dispersed in a dispersion medium, then introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000), and after irradiating with ultrasound of about 28 kHz at an output of 60 W, the average particle size (D50) at the 50% reference of the particle size distribution in the measuring device can be calculated.

[0026] In one embodiment, the average particle size can be measured by the various methods described above, for example, using a particle size analyzer.

[0027] In one embodiment, the thickness may be measured using an SEM or TEM image of a cross-section, but is not limited thereto and may be measured by any method capable of measuring thickness in the field. The thickness may be an average thickness.

[0028] In one embodiment, crystalline carbon and amorphous carbon can be classified by X-ray diffraction analysis. The crystalline carbon includes natural graphite and artificial graphite. Natural graphite refers to naturally occurring graphite obtained by separation from minerals, and has a d002 of 3.350 Å to 3.360 Å when analyzed by X-ray diffraction, and artificial graphite refers to graphite produced by graphitization, and has a d002 of 3.355 Å to 3.365 Å when analyzed by X-ray diffraction. Amorphous carbon has a d002 of 3.34 Å or less when analyzed by X-ray diffraction. The X-ray diffraction analysis (XRD) can be performed using an X-ray diffraction analyzer, such as X'Pert (manufacturer: Malvern Panalytical), with CuKα rays as the target line, and the monochromator can be removed to improve peak intensity resolution. The measurement conditions may be 2θ=10° to 80°, scan speed (° / S)=0.044 to 0.089, and step size (° / step)=0.013 to 0.039.

[0029] An anode according to one embodiment comprises a sulfide-based solid electrolyte and a sulfur-containing additive that is glass or glass-ceramic, which has an endothermic peak appearing at 180°C to 220°C when measured by differential scanning calorimetry (DSC).

[0030] When measuring by differential scanning calorimetry, the appearance of an endothermic peak at 180°C to 220°C indicates that an endothermic reaction occurs at 180°C to 220°C. When a sulfur-containing additive undergoes an endothermic reaction, it can become crystallized, thereby improving the safety of the battery.

[0031] In order to improve the efficiency and lifespan characteristics of the anode, a solid electrolyte is used in the anode, but when the solid electrolyte is mixed with the anode active material, an exothermic reaction of about 200°C occurs, which can result in a high heat generation. This can lead to ignition and explosion of the battery, resulting in degraded battery safety.

[0032] The anode according to one embodiment includes an additive that undergoes an endothermic reaction at around 200°C, for example, between 180°C and 220°C, so the additive can absorb heat generated during an exothermic reaction caused by the solid electrolyte, and can also absorb heat even when the battery is exposed to a high temperature of about 200°C. Therefore, ignition and explosion of the battery can be suppressed, and as a result, the safety of the battery can be improved.

[0033] In one embodiment, the differential scanning calorimetry can be measured using a differential scanning calorimeter, and the differential scanning calorimeter may be a modulated differential scanning calorimeter (MDSC), for example, a temperature-modulated differential scanning calorimeter (TMDSC). Alternatively, it may be performed using a TA Instruments Discovery DSC 250 instrument.

[0034] In addition, differential scanning calorimetry measurements can be performed under conditions where the change in heat quantity is measured while heat-treating the sulfur-containing additive at 40°C to 100°C and at a heating rate of 1°C / min to 10°C / min up to 300°C to 500°C.

[0035] According to one embodiment, the sulfur-containing additive is glass or glass-ceramic, and can crystallize at 150°C to 250°C and have the advantage of being able to cause an endothermic reaction. In one embodiment, glass refers to amorphous. When the sulfur-containing additive is crystalline, it cannot absorb heat generated during an exothermic reaction caused by a solid electrolyte, and it cannot absorb heat even when the battery is exposed to high temperatures.

[0036] A sulfur-containing additive according to one embodiment can maintain glass or glass-ceramic even within a battery containing a positive electrode containing the same, and thus can cause an endothermic reaction in which it absorbs heat generated during an exothermic reaction and changes into a crystalline form, thereby exhibiting an improved safety effect due to the absorption of heat. If the sulfur-containing additive is crystalline, an endothermic reaction does not occur, and thus the improved safety effect cannot be obtained.

[0037] In one embodiment, it can be determined by X-ray diffraction (XRD) peak analysis that the sulfur-containing additive is glass or glass-ceramic. For example, when measuring X-ray diffraction peaks, for example using CuKα rays as the target line, if peaks appear at 2θ=28° to 35° and 2θ=15° to 20°, it can be said to be crystalline. The glass according to one embodiment is amorphous, and when measuring X-ray diffraction peaks, for example using CuKα rays as the target line, peaks do not appear at 2θ=28° to 35° and 2θ=15° to 20°, or only background intensity may appear. In addition, the glass-ceramic according to one embodiment is an intermediate phase between crystalline and amorphous, and when measuring X-ray diffraction peaks using CuKα rays as a target line, the background intensity may be 20% to 100% relative to the intensity of the main peak appearing at 2θ = 29° to 31°. The intensity may refer to the height in a graph showing the X-ray diffraction measurement results.

[0038] In one embodiment, the XRD measurement is performed using CuKα rays as the target line, and to improve peak intensity resolution, the measurement can be performed by removing the monochromator device. The measurement conditions may be 2θ = 10° to 80°, the scan speed (° / S) 0.01 to 0.05, and the step size (° / step) 0.013° / step to 0.039° / step.

[0039] In one embodiment, the content of the sulfur-containing additive may be 5% to 31% by weight, 5% to 30% by weight, 7% to 31% by weight, 7% to 20% by weight, or 7% to 15% by weight, with respect to 100% by weight of the solid electrolyte and the sulfur-containing additive. When the content of the sulfur-containing additive falls within the above range, heat absorption by endothermic reaction can be carried out more sufficiently, thereby further improving battery safety.

[0040] A sulfur-containing additive according to one embodiment may be glass, glass ceramic, or a combination thereof, and may be glass, glass ceramic, or a combination thereof that does not react with the sulfide-based solid electrolyte.

[0041] The above sulfur-containing additives are xLi2S-(100-x)P2S5 (where x is an integer from 50 to 90), xLi2S-(100-x)SiS2 (where x is an integer from 50 to 90), Li2SO4, LiI, LiBr, xLi2S-(100-xy)P2S 5-y P2O5((x is an integer from 50 to 90, and y is an integer from 10 to 30) , y GeS2 (y is an integer from 10 to 20), or a combination thereof.

[0042] Examples of the above xLi2S-(100-x)P2S5 (where x is an integer from 50 to 90) may be 75Li2S-25P2S5, 70Li2S-30P2S5, 87.5Li2S-12.5P2S5, or a combination thereof.

[0043] In one embodiment, the sulfide-based solid electrolyte may be an argyrodite-type sulfide-based solid electrolyte.

[0044] For example, the above sulfide-based solid electrolyte is Li2S-P2S5-LiX (where X is a halogen element, e.g., I or Cl), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (m and n are integers greater than or equal to 0 and less than or equal to 12, respectively, and Z is one of Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p and q are integers greater than or equal to 0 and less than or equal to 12, respectively; M is one of P, Si, Ge, B, Al, Ga, and In), Li a M b P c S d A e (a, b, c, d and e are each integers from 0 to 12, provided that a, b, c, d and e are not all 0, M is a metal other than Li or a combination of multiple metals other than Li, e.g., Ge, Sn, Si or a combination thereof, and A is one of F, Cl, Br, or I) or a combination thereof.

[0045] In one embodiment, the sulfide-based solid electrolyte is Li a M b P c S d A e (a, b, c, d, and e are each integers from 0 to 12 (provided that a, b, c, d, and e are not all 0), M is a metal excluding Li or a combination of multiple metals excluding Li, e.g., Ge, Sn, Si, or a combination thereof, and A is one of F, Cl, Br, or I). As a specific example, Li7-x PS 6-x A x It can be expressed by the chemical formula (where x is 0.2 or greater and 1.8 or less, and A is F, Cl, Br, or I). Specifically, the azirodite-type sulfide is Li3PS4, Li7P3S 11 , Li7PS6, Li6PS5Cl, Li6PS5Br, Li 5.8 PS 4.8 Cl 1.2 , Li 6.2 PS 5.2 Br 0.8 It could be the back.

[0046] These sulfide-based solid electrolytes, for example, azirodite-type sulfide-based solid electrolytes, have an ionic conductivity of 10 at room temperature, which is the ionic conductivity of a typical liquid electrolyte. -4 to 10 -2 It has high ionic conductivity close to the S / cm range and can form a tight bond between the positive active material and the solid electrolyte without causing a decrease in ionic conductivity, and furthermore, can form a tight interface between the electrode layer and the solid electrolyte layer. An all-solid-state battery including this can improve battery performance such as rate characteristics, Coulomb efficiency, and lifespan characteristics.

[0047] According to one embodiment, the sulfide-based solid electrolyte may be particles, and the average particle size (D50) of the sulfide-based solid electrolyte particles may be 5.0 μm or less, for example, 0.1 μm to 5.0 μm, 0.1 μm to 4.0 μm, 0.1 μm to 3.0 μm, 0.5 μm to 2.0 μm, or 0.1 μm to 1.5 μm. Alternatively, the sulfide-based solid electrolyte particles may be small particles having an average particle size (D50) of 0.1 μm to 1.0 μm, or large particles having an average particle size (D50) of 1.5 μm to 5.0 μm. Sulfide-based solid electrolyte particles with such particle size ranges can effectively penetrate between solid particles within the battery, and have excellent contact with the electrode active material and connectivity between solid electrolyte particles. The average particle size of the sulfide-based solid electrolyte particles may be measured using a microscopic image, for example, by measuring the size of about 20 particles in a scanning electron microscope image to obtain the particle size distribution and calculating D50 from it.

[0048] The above sulfide-based solid electrolyte may be 95% to 70% by weight, 80% to 93% by weight, or 85% to 93% by weight with respect to 100% by weight of the above sulfide-based solid electrolyte and the sulfur-containing additive.

[0049] An anode according to one embodiment comprises a current collector and an anode active material layer located on the current collector. The sulfide-based solid electrolyte and the sulfur-containing additive are included in the anode active material layer, and the anode active material layer comprises an anode active material.

[0050] In one embodiment, the sulfur-containing additive may be glass or glass-ceramic in the anode.

[0051] In one embodiment, the sulfide-based solid electrolyte, the sulfur-containing additive, and the cathode active material may be physically mixed and contained within the cathode active material layer. Being physically mixed with the cathode active material means that the sulfur-containing additive is entirely dispersed within the cathode active material layer. If the sulfur-containing additive is entirely dispersed within the cathode active material layer, improved ion conductivity and battery performance can be exhibited.

[0052] If the surface of the positive electrode active material is coated with a sulfur-containing additive, ion conductivity may be reduced. The coated state refers to a condition where the sulfur-containing additive is positioned in contact with the surface of the positive electrode active material. Furthermore, this coated state implies that the positive electrode active material is first coated with a sulfur-containing additive, and the resulting product is then mixed with a conductive material.

[0053] The above positive active material layer may further include a conductive material.

[0054] In the above positive active material layer, the content of the sulfide-based solid electrolyte may be 1% to 40% by weight, 5% to 30% by weight, or 10% to 15% by weight with respect to 100% by weight of the positive active material layer, and the sulfur-containing additive may be 0.01% to 50% by weight, 0.1% to 20% by weight, or 0.5% to 10% by weight with respect to 100% by weight of the positive active material layer. In addition, the content of the positive active material may be 50% to 99% by weight, 70% to 97% by weight, or 80% to 95% by weight with respect to 100% by weight of the positive active material layer, and the content of the conductive material may be 0.1% to 2% by weight, 0.15% to 1.5% by weight, or 0.2% to 1% by weight with respect to 100% by weight of the positive active material layer.

[0055] The above positive active material layer may include a binder. The content of the binder may be 0.1% to 20% by weight, 1% to 15% by weight, and 2.5% to 10% by weight with respect to 100% by weight of the positive active material layer.

[0056] The above binder serves to adhere the positive active material particles well to each other and also to adhere the positive active material well to the current collector. Representative examples include polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, diacetylcellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc., but are not limited thereto.

[0057] The above-mentioned positive active material may be applied without limitation as long as it is commonly used in all-solid-state secondary batteries. For example, the above-mentioned positive active material may be a compound capable of reversible intercalation and deintercalation of lithium, and may include a compound represented by any one of the following chemical formulas.

[0058] Li a A 1-b X b D2(0.90≤a≤1.8, 0≤b≤0.5);

[0059] Li a A 1-b X b O 2-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05);

[0060] Li a E 1-b X b O 2-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05);

[0061] Li a HAVE BEEN 2-b X b O 4-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05);

[0062] Li a Ni 1-b-c Co b X c D α (0.90≤ a ≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α≤2);

[0063] Li a Ni 1-b-c Co b X c O 2-α T α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α<2);

[0064] Li a Ni 1-b-c Co b X c O 2-α T2(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α<2);

[0065] Li a Ni 1-b-c Mr b X c D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α≤2);

[0066] Li a Ni 1-b-c Mr b X c O 2-α T α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α<2);

[0067] Li a Ni 1-b-c Mr b X c O 2-α T2(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α<2);

[0068] Li a Ni b E c G d O2(0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤0.1);

[0069] Li a Ni b Co c Mn d G e O2(0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0.001≤e≤0.1);

[0070] Li a NiG b O2(0.90≤a≤1.8, 0.001≤b≤0.1);

[0071] Li a CoG b O2(0.90≤a≤1.8, 0.001≤b≤0.1);

[0072] Li a Mn 1-b G b O2(0.90≤a≤1.8, 0.001≤b≤0.1);

[0073] Li a Mn2G b O4(0.90≤a≤1.8, 0.001≤b≤0.1);

[0074] Li a Mn 1-g G g PO4(0.90≤a≤1.8, 0≤g≤0.5);

[0075] QO2; QS2; LiQS2;

[0076] V2O5; LiV2O5;

[0077] LiZO2;

[0078] LiNiVO4;

[0079] Li (3-f) J2(PO4)3(0≤f≤2);

[0080] Li (3-f) Fe2(PO4)3(0≤f≤2);

[0081] Li a FePO4(0.90≤a≤1.8).

[0082] In the above chemical formulas, A is selected from the group consisting of Ni, Co, Mn, and combinations thereof; X is selected from the group consisting of Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements, and combinations thereof; D is selected from the group consisting of O, F, S, P, and combinations thereof; E is selected from the group consisting of Co, Mn, and combinations thereof; T is selected from the group consisting of F, S, P, and combinations thereof; G is selected from the group consisting of Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, and combinations thereof; Q is selected from the group consisting of Ti, Mo, Mn, and combinations thereof; Z is selected from the group consisting of Cr, V, Fe, Sc, Y, and combinations thereof; and J is selected from the group consisting of V, Cr, Mn, Co, Ni, Cu, and combinations thereof.

[0083] The above-mentioned positive electrode active material may be, for example, lithium cobalt oxide (LCO), lithium nickel oxide (LNO), lithium nickel cobalt oxide (NC), lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium nickel manganese oxide (NM), lithium manganese oxide (LMO), or lithium iron phosphate oxide (LFP).

[0084] The above positive active material may include a lithium nickel-based oxide represented by the following chemical formula 1, a lithium cobalt-based oxide represented by the following chemical formula 2, a lithium iron phosphate-based compound represented by the following chemical formula 3, or a combination thereof.

[0085] [Chemical Formula 1]

[0086] Li a1 Ni x1 M 1 y1 M 2 1-x1-y1 O2

[0087] In the above Chemical Formula 1, 0.9≤a1≤1.8, 0.3≤x1≤1, 0≤y1≤0.7, and M 1 and M 2 Each is independently one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, F, Fe, Mg, Mn, Mo, Nb, P, S, Si, Sr, Ti, V, W, and Zr.

[0088] [Chemical Formula 2]

[0089] Li a2 Co x2 M 3 1-x2 O2

[0090] In the above chemical formula 2, 0.9≤a2≤1.8, 0.6≤x2≤1, and M 3 It is one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Cr, Cu, F, Fe, Mg, Mn, Mo, Nb, P, S, Si, Sr, Ti, V, W, and Zr.

[0091] [Chemical Formula 3]

[0092] Li a3 Fe x3 M 4 (1-x3) PO4

[0093] In the above chemical formula 3, 0.9≤a3≤1.8, 0.6≤x3≤1, and M 4 is one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, F, Fe, Mg, Mn, Mo, Nb, P, S, Si, Sr, Ti, V, W, and Zr.

[0094] In one embodiment, the positive electrode active material may be a high-nickel (high-Ni) oxide containing 60 mol% or more, 80 mol% or more, or 90 mol% or more of nickel. The positive electrode active material according to one embodiment may be a lithium nickel-based oxide of Formula 1, and, for example, may be a high-nickel (high-Ni) oxide in which x1 is 0.6 to 1, 0.8 to 1, or 0.9 to 1. Although the high-nickel oxide positive electrode active material can exhibit high capacity, when used with a sulfide-based solid electrolyte, a significant exothermic reaction of about 200°C occurs, which can lead to a significant problem of deterioration in battery safety. In one embodiment, since a sulfur-containing additive is used in the positive electrode, the exothermic reaction can be effectively suppressed, and thus the problem associated with using the high-nickel oxide positive electrode active material with a sulfide-based solid electrolyte can be effectively prevented. Therefore, the effect of using the sulfur-containing additive can be maximized when used with the high-nickel oxide positive electrode active material.

[0095] Average particle size (D of the above positive active material) 50 The particle size can be 1 μm to 25 μm, for example, 3 μm to 25 μm, 5 μm to 25 μm, 5 μm to 20 μm, 8 μm to 20 μm, or 10 μm to 18 μm. A positive electrode active material having such a particle size range can be harmoniously mixed with other components within the positive electrode active material layer and can achieve high capacity and high energy density.

[0096] The above positive active material may be in the form of secondary particles formed by the aggregation of a plurality of primary particles, or in the form of a single particle. In addition, the above positive active material may be spherical or have a shape close to spherical, or may be polyhedral or amorphous.

[0097] In one embodiment, the conductive material is used to impart conductivity to the electrode and can improve electrical conductivity. The conductive material may include, for example, carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjenblack, carbon fibers, carbon nanotubes; metal-based materials in the form of metal powder or metal fibers containing copper, nickel, aluminum, silver, etc.; conductive polymers such as polyphenylene derivatives; or a combination thereof.

[0098] In one embodiment, the current collector comprises, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof, and may be in the form of a foil or sheet.

[0099] All-solid-state battery

[0100] Another embodiment provides an all-solid-state secondary battery including the anode.

[0101] The above-described all-solid-state secondary battery includes a positive electrode, a negative electrode, and a solid electrolyte layer located between the positive electrode and the negative electrode. The positive electrode may be a positive electrode according to one embodiment. The above-described all-solid-state secondary battery may also be referred to as an all-solid-state battery or an all-solid-state lithium secondary battery.

[0102] FIG. 1 is a cross-sectional view of an all-solid-state secondary battery according to one embodiment. Referring to FIG. 1, the all-solid-state secondary battery (100) may have a structure in which an electrode assembly is stacked, comprising a negative electrode (400) including a negative electrode current collector (401) and a negative electrode active material layer (403), a solid electrolyte layer (300), and a positive electrode (200) including a positive electrode active material layer (203) and a positive electrode current collector (201), and the assembly is housed in a case such as a pouch. The all-solid-state secondary battery (100) may further include an elastic layer (500) on the outer side of at least one of the positive electrode (200) and the negative electrode (400). FIG. 1 shows a single electrode assembly including a negative electrode (400), a solid electrolyte layer (300), and a positive electrode (200), but an all-solid-state battery may be manufactured by stacking two or more electrode assemblies.

[0103] [cathode]

[0104] A negative electrode for an all-solid-state secondary battery may, for example, include a current collector and a negative electrode active material layer located on the current collector. The negative electrode active material layer may include a negative electrode active material and may further include a binder, a conductive material, and / or a solid electrolyte.

[0105] The above negative electrode active material may include a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

[0106] A material capable of reversibly intercalating / deintercalating the lithium ions may include a carbon-based negative electrode active material, for example, crystalline carbon, amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as amorphous, plate-like, flake-like, spherical, or fibrous natural graphite or artificial graphite, and examples of the amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, calcined coke, etc.

[0107] As the above lithium metal alloy, an alloy of lithium with one or more metals selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn may be used.

[0108] As a material capable of doping and undoping the above lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material may be used, and the Si-based negative electrode active material may include silicon, a silicon-carbon composite, or SiO₂. x (0 <x≤2), Si-Q 합금(상기 Q는 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소, 15족 원소, 16족 원소, 전이금속, 희토류 원소 및 이들의 조합으로 이루어진 군에서 선택되는 원소이며, Si은 아님), 상기 Sn계 음극 활물질로는 Sn, SnO2, Sn-R 합금(상기 R은 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소, 15족 원소, 16족 원소, 전이금속, 희토류 원소 및 이들의 조합으로 이루어진 군에서 선택되는 원소이며, Sn은 아님) 등을 들 수 있고, 또한 이들 중 적어도 하나와 SiO2를 혼합하여 사용할 수도 있다. 상기 원소 Q 및 R로는 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, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, 및 이들의 조합으로 이루어진 군에서 선택되는 것을 사용할 수 있다.

[0109] The silicon-carbon composite may be, for example, a silicon-carbon composite comprising a core containing crystalline carbon and silicon particles and an amorphous carbon coating layer located on the surface of the core. The crystalline carbon may be artificial graphite, natural graphite, or a combination thereof. The amorphous carbon may be pitch carbon, soft carbon, hard carbon, mesophase pitch carbide, calcined coke, carbon fiber, or a combination thereof. In this case, the silicon content may be 10% to 50% by weight of the total weight of the silicon-carbon composite. Additionally, the content of the crystalline carbon may be 10% to 70% by weight of the total weight of the silicon-carbon composite, and the content of the amorphous carbon may be 20% to 40% by weight of the total weight of the silicon-carbon composite. Additionally, the thickness of the amorphous carbon coating layer may be 5nm to 100nm.

[0110] The average particle size (D50) of the silicon particles may be 10 nm to 20 µm, for example, 10 nm to 500 nm. The silicon particles may exist in an oxidized form, wherein the atomic content ratio of Si:O within the silicon particles indicating the degree of oxidation may be 99:1 to 33:67. The silicon particles are SiO x It can be a particle, and in this case, SiO x In this case, the range of x may be greater than 0 and less than 2. Here, the average particle size (D50) is measured by a particle size analyzer using laser diffraction and refers to the diameter of a particle with a cumulative volume of 50% in the particle size distribution.

[0111] The above Si-based negative electrode active material or Sn-based negative electrode active material may be used in combination with a carbon-based negative electrode active material. The mixing ratio of the Si-based negative electrode active material or Sn-based negative electrode active material and the carbon-based negative electrode active material may be 1:99 to 90:10 by weight.

[0112] The content of the negative electrode active material in the above negative electrode active material layer may be 95% to 99% by weight with respect to the total weight of the negative electrode active material layer.

[0113] In one embodiment, the negative electrode active material layer further comprises a binder and optionally further comprises a conductive material. The content of the binder in the negative electrode active material layer may be 1% to 5% by weight based on the total weight of the negative electrode active material layer. Additionally, when further comprising a conductive material, the negative electrode active material layer may comprise 90% to 98% by weight of the negative electrode active material, 1% to 5% by weight of the binder, and 1% to 5% by weight of the conductive material.

[0114] The above binder serves to effectively bond the negative electrode active material particles to each other and also to effectively bond the negative electrode active material to the current collector. The above binder may include a non-aqueous binder, an aqueous binder, or a combination thereof.

[0115] The above-mentioned non-aqueous binder may include, for example, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, a polymer comprising ethylene oxide, an ethylene propylene copolymer, polystyrene, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, or a combination thereof.

[0116] Examples of the above-mentioned water-based binders include rubber-based binders or polymer resin binders. The above-mentioned rubber-based binder may be selected from styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile-butadiene rubber, acrylic rubber, butyl rubber, fluororubber, and combinations thereof. The above-mentioned polymer resin binder may be selected from polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, ethylenepropylenediene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0117] The binder may be a cellulose-based compound, or the cellulose-based compound may be used together with the aqueous binder. As the cellulose-based compound, one or more types such as carboxymethyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, or alkali metal salts thereof may be mixed and used. Na, K, or Li may be used as the alkali metal. The cellulose-based compound may serve as a binder or as a thickener capable of imparting viscosity. Accordingly, the cellulose-based compound may be used in an appropriate amount within the binder content, but for example, it may be 0.1 to 3 parts by weight per 100 parts by weight of the negative electrode active material.

[0118] The above conductive material is used to impart conductivity to an electrode and may include, for example, carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanotubes; metal-based materials in the form of metal powder or metal fibers including copper, nickel, aluminum, silver, etc.; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0119] The above-mentioned cathode current collector may be selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and combinations thereof.

[0120] As another example, the negative electrode for the all-solid-state battery may be a precipitation type negative electrode. The precipitation type negative electrode refers to a negative electrode that does not contain a negative electrode active material when assembling the battery, but where lithium metal, etc., is precipitated during charging of the battery and acts as the negative electrode active material.

[0121] FIG. 2 is a schematic cross-sectional view of an all-solid-state secondary battery including a precipitation type negative electrode according to one embodiment. Referring to FIG. 2, the precipitation type negative electrode (400') may include a current collector (401) and a negative electrode coating layer (405) located on the current collector. An all-solid-state battery having such a precipitation type negative electrode (400') is initially charged in a state where no negative electrode active material is present, and during charging, a high-density lithium metal, etc. is precipitated between the current collector (401) and the negative electrode coating layer (405) to form a lithium metal layer (404), which can act as a negative electrode active material. Accordingly, in an all-solid-state battery that has undergone one or more charges, the precipitation type negative electrode (400') may include a current collector (401), a lithium metal layer (404) located on the current collector, and a negative electrode coating layer (405) located on the metal layer. The above lithium metal layer (404) refers to a layer in which lithium metal, etc. is precipitated during the charging process of the battery, and can be referred to as a metal layer or a negative electrode active material layer.

[0122] The above cathode coating layer (405) may include a metal, a carbon material, or a combination thereof that acts as a catalyst.

[0123] The above metal may include, for example, gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, zinc, or a combination thereof, and may be composed of one of these or may be composed of several types of alloys. When the above metal exists in the form of particles, the average particle size (D50) may be about 4 μm or less, and for example, 10 nm to 4 μm.

[0124] The carbon material may be, for example, crystalline carbon, amorphous carbon, or a combination thereof. The crystalline carbon may be, for example, natural graphite, artificial graphite, mesophase carbon microbeads, or a combination thereof. The amorphous carbon may be, for example, pitch carbon, soft carbon, hard carbon, mesophase pitch carbide, calcined coke, carbon fiber, or a combination thereof.

[0125] When the above-mentioned cathode coating layer (405) includes both the metal and the carbon material, the mixing ratio of the metal and the carbon material may be, for example, a weight ratio of 1:10 to 2:1. In this case, the precipitation of lithium metal can be effectively promoted and the characteristics of the all-solid-state battery can be improved. The above-mentioned cathode coating layer (405) may include, for example, a carbon material supported with a catalyst metal, or may include a mixture of metal particles and carbon material particles.

[0126] The above cathode coating layer (405) may, for example, include the metal and amorphous carbon, and in this case, can effectively promote the precipitation of lithium metal.

[0127] The above cathode coating layer (405) may further include a binder, and the binder may be a conductive binder. Additionally, the above cathode coating layer (405) may further include general additives such as fillers, dispersants, ion conductive materials, etc.

[0128] The conductive binder may include a non-aqueous binder, an aqueous binder, or a combination thereof.

[0129] The above-mentioned non-aqueous binder may include, for example, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, a polymer comprising ethylene oxide, an ethylene propylene copolymer, polystyrene, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, or a combination thereof.

[0130] Examples of the above-mentioned water-based binders include rubber-based binders or polymer resin binders. The above-mentioned rubber-based binder may be selected from styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile-butadiene rubber, acrylic rubber, butyl rubber, fluororubber, and combinations thereof. The above-mentioned polymer resin binder may be selected from polyethylene oxide, polyvinylpyrrolidone, polyepichorhydrin, polyphosphazene, polyacrylonitrile, ethylenepropylenediene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0131] When a water-based binder is used as the above-mentioned cathode binder, a thickener capable of imparting viscosity may be used together, and the thickener may include, for example, a cellulose-based compound. The cellulose-based compound may include carboxymethyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, alkali metal salts thereof, or combinations thereof. Na, K, or Li may be used as the alkali metal. The content of such a thickener may be 0.1 to 3 parts by weight per 100 parts by weight of the cathode active material.

[0132] The binder may be 1% to 15% by weight with respect to 100% by weight of the entire cathode coating layer. For example, the binder may be 1% to 14% by weight, 1% to 12% by weight, 1% to 10% by weight, 2% to 8%, or 2% to 7% by weight with respect to 100% by weight of the entire cathode coating layer.

[0133] When the above binder is included in the negative electrode coating layer of an all-solid-state battery within the above content range, electrical resistance and adhesion are improved, and the characteristics of the all-solid-state battery (battery capacity and output characteristics) can be improved.

[0134] The thickness of the above cathode coating layer (405) may be, for example, 100 nm to 20 µm, or 500 nm to 10 µm, or 1 µm to 5 µm.

[0135] The above-mentioned cathode coating layer may further include a solid electrolyte, and the solid electrolyte may be an inorganic solid electrolyte such as a sulfide-based solid electrolyte, an oxide-based solid electrolyte, or a halide-based solid electrolyte, or a solid polymer electrolyte.

[0136] In one embodiment, the sulfide-based solid electrolyte is Li2S-P2S5, Li2S-P2S5-LiX (where X is a halogen element, e.g., I or Cl), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (m and n are integers greater than or equal to 0 and less than or equal to 12, respectively, and Z is one of Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q(p and q are integers greater than or equal to 0 and less than or equal to 12, respectively; M is one of P, Si, Ge, B, Al, Ga, and In), Li a M b P c S d A e (a, b, c, d, and e are each integers from 0 to 12, provided that a, b, c, d, and e are not all 0, M is Ge, Sn, Si, or a combination thereof, and A is one of F, Cl, Br, or I). The sulfide-based solid electrolyte may be, for example, Li 7-x PS 6-x F x (0≤x≤2), Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), Li 7-x PS 6-x I x (0≤x≤2), or Li 7-x-y PS 6-x―y Cl x Br y (0≤x≤2, 0.2≤y≤1) may be possible. Also, specifically Li3PS4, Li7P3S 11 , Li7PS6, Li6PS5Cl, Li6PS5Cl, Li6PS5I, Li6PS5Br, Li 5.8 PS 4.8 Cl 1.2 , Li 6.2 PS 5.2 Br 0.8 It could be the back.

[0137] In one embodiment, the sulfide-based solid electrolyte may be an argyrodite-type sulfide-based solid electrolyte. The argyrodite-type sulfide-based solid electrolyte is, for example, Li a M b P c S d A e(a, b, c, d and e are all integers between 0 and 12, but not all of a, b, c, d and e are 0, M is Ge, Sn, Si or a combination thereof, and A is one of F, Cl, Br, or I) may be possible.

[0138] Specific examples include Li3PS4 and Li7P3S 11 , Li7PS6, Li6PS5Cl, Li6PS5Br, Li 5.8 PS 4.8 Cl 1.2 , Li 6.2 PS 5.2 Br 0.8 , Li6PS5I, Li 5.75 PS 4.75 Cl 1.25 , (Li 5.69 Cu 0.06 )PS 4.75 Cl 1.25 , (Li 5.72 Cu 0.03 )PS 4.75 Cl 1.25 , (Li 5.69 Cu 0.06 )P(S 4.70 (SO4) 0.05 )Cl 1.25 , (Li 5.69 Cu 0.06 )P(S 4.60 (SO4) 0.15 )Cl 1.25 , (Li 5.72 Cu 0.03 )P(S 4.725 (SO4) 0.025 )Cl 1.25 , (Li 5.72 Na 0.03 )P(S 4.725 (SO4) 0.025 )Cl 1.25 , Li 5.75 P(S 4.725 (SO4) 0.025 )Cl 1.25 , or a combination thereof may be included, but is not limited thereto.

[0139] The sulfide-based solid electrolyte may be amorphous, crystalline, or a mixture thereof. For example, the sulfide-based solid electrolyte may be obtained by mixing Li2S and P2S5 in a molar ratio of 50:50 to 90:10 or a molar ratio of 50:50 to 80:20. Within the above mixing ratio range, a sulfide-based solid electrolyte having excellent ionic conductivity can be manufactured. The ionic conductivity may be further improved by including other components such as SiS2, GeS2, B2S3, etc.

[0140] Mechanical milling or the solution method can be applied as mixing methods for sulfur-containing raw materials to manufacture sulfide-based solid electrolytes. Mechanical milling is a method in which starting materials are placed in a reactor and vigorously stirred with a ball mill or similar device to finely pulverize and mix the starting materials. When using the solution method, starting materials are mixed in a solvent to obtain a solid electrolyte as a precipitate. Furthermore, if heat treatment is performed after mixing, the crystals of the solid electrolyte can become more robust and the ionic conductivity can be improved. For example, a sulfide-based solid electrolyte can be manufactured by mixing sulfur-containing raw materials and heat-treating them two or more times; in this case, a robust sulfide-based solid electrolyte with high ionic conductivity can be produced.

[0141] Of course, commercially available solid electrolytes can also be used for sulfide-based solid electrolytes.

[0142] The above oxide-based solid electrolyte is, for example, Li 1+x Ti 2-x Al(PO4)3(LTAP)(0≤x≤4), Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 (0 <x<2, 0≤y<3), BaTiO3, Pb(Zr,Ti)O3(PZT), Pb 1-x La x Zr 1-y Ti yO3(PLZT)(0 <x<1, 0≤y<1), Pb(Mg3Nb 2 / 3 )O3-PbTiO3(PMN-PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, Lithium Phosphate (Li3PO4), Lithium Titanium Phosphate (Li x Ti y (PO4)3, 0 <x<2, 0<y<3), Li 1+x+y (Al, Ga) x (Ti, Ge) 2-x Si y P 3-y O 12 (0≤x≤1, 0≤y≤1), lithium lanthanum titanate(Li x La y TiO3, 0 <x<2, 0<y<3), Li2O, LiAlO2, Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2계 세라믹스, 가넷(Garnet)계 세라믹스 Li 3+x La3M2O 12 (M= Te, Nb, or Zr, x is an integer from 1 to 10), or may include a mixture thereof.

[0143] The above solid polymer electrolyte is, for example, polyethylene oxide, poly(diallyldimethylammonium)trifluoromethanesulfonylimide (poly(diallyldimethylammonium)TFSI), Cu3N, Li3N, LiPON, Li3PO4·Li2S·SiS2, Li2S·GeS2·Ga2S3, Li2O·11Al2O3, Na2O·11Al2O3, (Na,Li) 1+x Ti 2-x Al x (PO4)3(0.1≤x≤0.9), Li 1+x Hf 2-x Al x (PO4)3(0.1≤x≤0.9), Na3Zr2Si2PO 12 , Li3Zr2Si2PO 12 , Na5ZrP3O 12 , Na5TiP3O12 , Na3Fe2P3O 12 , Na4NbP3O 12 , Na-Silicates, Li 0.3 La 0.5 TiO3, Na5MSi4O 12 (M is a rare earth element such as Nd, Gd, or Dy) Li5ZrP3O 12 , Li5TiP3O 12 , Li3Fe2P3O 12 , Li4NbP3O 12 , Li 1+x (M,Al,Ga) x (Ge 1-y Ti y ) 2-x (PO4)3(0≤x≤0.8, 0≤y≤1.0, M is Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm or Yb), Li 1+x+y Q x Ti 2-x Si y P 3-y O 12 (0 <x≤0.4, 0<y≤0.6, Q는 Al 또는 Ga), Li6BaLa2Ta2O 12 , Li7La3Zr2O 12 , Li5La3Nb2O 12 , Li5La3M2O 12 (M is Nb, Ta) and Li 7+x A x La 3-x Zr2O 12 (0 <x<3, A는 Zn) 중에서 선택된 하나 이상을 포함할 수 있다.

[0144] The above halide-based solid electrolyte may include a Li element, an M element (M is a metal other than Li), and an X element (X is a halogen). Examples of X include F, Cl, Br, and I. In particular, for the halide-based solid electrolyte, at least one of Br and Cl is suitable as X. Additionally, examples of M include metal elements such as Sc, Y, B, Al, Ga, and In.

[0145] The composition of the above halide-based solid electrolyte is not particularly limited, but Li 6-3a M a Br b Cl c (In the formula, M is a metal other than Li, and 0 <a<2, 0≤b≤6, 0≤c≤6, b+c=6)로 표현될 수 있다. 이때, 상기 a는 0.75 이상일 수 있고, 1 이상일 수 있고, a는, 1.5 이하일 수 있다. 상기 b는 1 이상일 수 있고, 2 이상일 수 있다. 또한, 상기 c는, 3 이상일 수 있고, 4 이상일 수도 있다. 상기 할라이드계 고체 전해질의 구체적인 예로는 Li3YBr6, Li3YCl6또는 Li3YBr2Cl4를 들 수 있다.

[0146] The above current collector may be, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof, and may be in the form of a foil or a sheet. The thickness of the negative electrode current collector may be 1 μm to 20 μm, 5 μm to 15 μm, or 7 μm to 10 μm.

[0147] The above-mentioned precipitation type cathode (400') may, for example, further include a thin film on the surface of the current collector, that is, between the current collector and the cathode coating layer. The thin film may include an element capable of forming an alloy with lithium. The element capable of forming an alloy with lithium may be, for example, gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, etc., and may be composed of one of these or composed of several types of alloys. The thin film can further flatten the precipitation shape of the lithium metal layer (404) and further improve the characteristics of the all-solid-state battery. The thin film may be formed by, for example, vacuum deposition, sputtering, plating, etc. The thickness of the thin film may be, for example, 1 nm to 500 nm.

[0148] [Solid Electrolyte Layer]

[0149] The solid electrolyte layer may include inorganic solid electrolytes such as sulfide-based solid electrolytes, oxide-based solid electrolytes, and halide-based solid electrolytes, or solid polymer electrolytes. The specific details of sulfide-based solid electrolytes, oxide-based solid electrolytes, halide-based solid electrolytes, and solid polymer electrolytes are as described above.

[0150] In one example, the solid electrolyte included in the anode or cathode and the solid electrolyte included in the solid electrolyte layer may contain the same compound or different compounds. For example, when both the anode and the solid electrolyte layer contain a azirodite-type sulfide-based solid electrolyte, the overall performance of the all-solid-state secondary battery may be improved.

[0151] Meanwhile, the average particle size (D) of the solid electrolyte contained in the anode 50 ) is the average particle size (D) of the solid electrolyte contained in the solid electrolyte layer. 50 It may be smaller than ). In this case, overall performance can be improved by increasing lithium ion mobility while maximizing the energy density of the all-solid-state battery. For example, the average particle size (D) of the solid electrolyte contained in the cathode. 50 ) may be 0.1 μm to 1.0 μm, or 0.1 μm to 0.8 μm, and the average particle size (D) of the solid electrolyte included in the solid electrolyte layer 50 The particle size ) can be 1.5 μm to 5.0 μm, or 2.0 μm to 4.0 μm, or 2.5 μm to 3.5 μm. When such a particle size range is satisfied, the energy density of the all-solid-state secondary battery is maximized, while lithium ion transport is facilitated to suppress resistance, thereby improving the overall performance of the all-solid-state secondary battery. Here, the average particle size (D) of the solid electrolyte 50) may be measured using a particle size analyzer utilizing laser diffraction. Alternatively, approximately 20 random particles may be selected from microscopic images such as those of a scanning electron microscope, their particle sizes measured, and their particle size distribution obtained, where D 50 You can also calculate the value.

[0152] The above solid electrolyte layer may further include a binder in addition to the solid electrolyte. In this case, styrene butadiene rubber, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, acrylate-based polymers, or combinations thereof may be used as the binder, but are not limited thereto, and any material used as a binder in the relevant technical field may be used. The above acrylate-based polymer may be, for example, butyl acrylate, polyacrylate, polymethacrylate, or a combination thereof.

[0153] The above solid electrolyte layer can be formed by adding a solid electrolyte to a binder solution, coating it onto a substrate film, and drying it. The solvent of the binder solution may be isobutyryl isobutylate, xylene, toluene, benzene, hexane, or a combination thereof. Since the process for forming the above solid electrolyte layer is widely known in the field, a detailed description will be omitted.

[0154] The thickness of the solid electrolyte layer may be, for example, 10 μm to 150 μm.

[0155] The above solid electrolyte layer may further include an alkali metal salt, and / or an ionic liquid, and / or a conductive polymer.

[0156] The above alkali metal salt may be, for example, a lithium salt. The content of the lithium salt in the solid electrolyte layer may be 1 M or more, for example, 1 M to 4 M. In this case, the lithium salt can improve ion conductivity by improving the lithium ion mobility of the solid electrolyte layer.

[0157] The above lithium salts are, for example, LiSCN, LiN(CN)2, Li(CF3SO2)3C, LiC4F9SO3, LiN(SO2CF2CF3)2, LiCl, LiF, LiBr, LiI, LiB(C2O4)2, LiBF4, LiBF3(C2F5), lithium bis(oxalato)borate (LiBOB), lithium oxalyldifluoroborate (LIODFB), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, LiN(SO2CF3)2), lithium bis(fluorosulfonyl)imide (LiFSI), It may include LiN(SO2F)2), LiCF3SO3, LiAsF6, LiSbF6, LiClO4, or a mixture thereof.

[0158] In addition, the lithium salt may be imide-based, for example, the imide-based lithium salt may include lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, LiN(SO2CF3)2) and lithium bis(fluorosulfonyl)imide (LiFSI, LiN(SO2F)2). The lithium salt can maintain or improve ionic conductivity by appropriately maintaining chemical reactivity with the ionic liquid.

[0159] The above ionic liquid refers to a salt or room temperature molten salt that has a melting point below room temperature, is in a liquid state at room temperature, and consists only of ions.

[0160] The above ionic liquid comprises a) one or more cations selected from ammonium-based, pyrrolidinium-based, pyridinium-based, pyrimidinium-based, imidazolium-based, piperidinium-based, pyrazolium-based, oxazolium-based, pyridazinium-based, phosphonium-based, sulfonium-based, triazolium-based, and mixtures thereof, and b) BF4 - , PF6 - , AsF6 - , SbF6 - , AlCl4 - , HSO4 - , ClO4 - , CH3SO3 - , CF3CO2 - , Cl - , Br - , I - , BF4 - , SO4 - , CF3SO3 - , (FSO2)2N - , (C2F5SO2)2N - , (C2F5SO2)(CF3SO2)N - , and (CF3SO2)2N - It may be a compound containing one or more anions selected from among.

[0161] The above ionic liquid may be one or more selected from the group consisting of, for example, N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide, N-butyl-N-methylpyrrolidinium bis(3-trifluoromethylsulfonyl)imide, 1-butyl-3-methylimidazoliium bis(trifluoromethylsulfonyl)amide, and 1-ethyl-3-methylimidazoliium bis(trifluoromethylsulfonyl)amide.

[0162] The weight ratio of the solid electrolyte to the ionic liquid in the above solid electrolyte layer may be 0.1:99.9 to 90:10, and for example, 10:90 to 90:10, 20:80 to 90:10, 30:70 to 90:10, 40:60 to 90:10, or 50:50 to 90:10. A solid electrolyte layer satisfying the above range can maintain or improve ionic conductivity by increasing the electrochemical contact area with the electrode. Accordingly, the energy density, discharge capacity, rate characteristics, etc. of the all-solid-state battery can be improved.

[0163] The above all-solid-state battery may be a unit cell having a structure of a positive electrode / solid electrolyte layer / negative electrode, a bicell having a structure of a negative electrode / solid electrolyte layer / positive electrode / solid electrolyte layer / negative electrode, or a stacked battery in which the structure of the unit cell is repeated.

[0164] The shape of the above-described solid-state battery is not particularly limited and may be, for example, coin-type, button-type, sheet-type, stacked-type, cylindrical-type, flat-type, etc. In addition, the above-described solid-state battery can be applied to large batteries used in electric vehicles, etc. For example, the above-described solid-state battery can be used in hybrid vehicles such as plug-in hybrid electric vehicles (PHEVs). In addition, it can be used in fields requiring a large amount of power storage, and for example, it can be used in electric bicycles or power tools.

[0165] An all-solid-state battery according to one embodiment can be manufactured by preparing a laminate by positioning a negative electrode, a positive electrode, and a solid electrolyte layer between the negative electrode and the positive electrode, and pressing the laminate.

[0166] The above pressurization process may be carried out in a range of 25°C to 90°C. Additionally, the above pressurization process may be carried out by applying pressure of 550 MPa or less, for example, 500 MPa or less, for example, in the range of 1 MPa to 500 MPa. The pressurization time may vary depending on the temperature and pressure, etc., and may be, for example, less than 30 minutes. The above pressurization process may be, for example, an isostatic press, a roll press, a plate press, or a warm isostatic press.

[0167] Examples and comparative examples of the present invention are described below. However, the following examples are merely one example of the present invention, and the present invention is not limited to the following examples.

[0168] (Example 1)

[0169] (1) Manufacturing of the anode

[0170] LiNi 0.8 Co 0.15 Mn 0.05 A cathode composition was prepared by mixing 85 wt% of O2 cathode active material, 12 wt% of Li6PS5Cl solid electrolyte, 1.2 wt% of 75Li2S-25P2S5 additive (glass), 0.5 wt% of carbon nanotube conductive material, and 1.3 wt% of binder in an N-methylpyrrolidone solvent. That is, the content of the additive was 10 wt% relative to the content of the additive and the solid electrolyte, which was 100 wt%.

[0171] The manufactured anode composition was coated onto an aluminum anode current collector using a bar coater, and the anode was manufactured by drying and rolling.

[0172] (2) Preparation of the cathode

[0173] Carbon black with a primary particle size (D50) of about 30 nm and silver (Ag) with an average particle size (D50) of about 60 nm were mixed in a weight ratio of 3:1, and 0.25 g of this mixture was added to 2 g of an N-methylpyrrolidone solution containing 7 wt% of a polyvinylidene fluoride binder and mixed to prepare a negative electrode active material layer composition.

[0174] The above cathode active material layer composition was applied to a nickel foil current collector using a bar coater and vacuum dried to manufacture a cathode.

[0175] (3) Preparation of solid electrolyte layer

[0176] A solid electrolyte solution was prepared by adding a crystalline azyrodite-type solid electrolyte Li6PS5Cl to an isobutylyl isobutylate binder solution containing an acrylate-based polymer (solid content: 50 wt%, mixing ratio of solid electrolyte to binder: 98.7:1.3 wt%).

[0177] The above solid electrolyte solution was applied to a release polytetrafluoroethylene film and dried to produce a solid electrolyte layer with a thickness of 100 μm.

[0178] (4) Manufacturing of a full-cell solid-state battery

[0179] The above positive electrode, the above solid electrolyte layer, and the above negative electrode were stacked in sequence, and a pressure of 490 MPa was applied to manufacture a full-cell solid-state battery.

[0180] (Example 2)

[0181] LiNi 0.8 Co 0.15 Mn 0.05A cathode was prepared in the same manner as in Example 1, except that a cathode composition was prepared by mixing 85 wt% of O2 cathode active material, 9.2 wt% of Li6PS5Cl solid electrolyte, 4 wt% of 75Li2S-25P2S5 additive (glass), 0.5 wt% of carbon nanotube conductive material, and 1.3 wt% of binder in an N-methylpyrrolidone solvent, that is, except that the content of the additive was changed to 30 wt% relative to 100 wt% of the content of the additive and the solid electrolyte.

[0182] An all-solid-state battery was manufactured by using the anode, the solid electrolyte layer of Example 1, and the cathode of Example 1, in the same manner as Example 1.

[0183] (Comparative Example 1)

[0184] LiNi 0.8 Co 0.15 Mn 0.05 A cathode was prepared in the same manner as in Example 1, except that a cathode composition was prepared by mixing 85 wt% of O2 cathode active material, 13.2 wt% of Li6PS5Cl solid electrolyte, 0.5 wt% of carbon nanotube conductive material, and 1.3 wt% of binder in an N-methylpyrrolidone solvent.

[0185] An all-solid-state battery was manufactured by using the anode, the solid electrolyte layer of Example 1, and the cathode of Example 1, in the same manner as Example 1.

[0186] (Comparative Example 2)

[0187] LiNi 0.8 Co 0.15 Mn 0.05A cathode was prepared in the same manner as in Example 1 above, except that a cathode composition was prepared by mixing 85 wt% of O2 cathode active material, 13.2 wt% of 75Li2S-25P2S5 additive (glass), 0.5 wt% of carbon nanotube conductive material, and 1.3 wt% of binder in an N-methylpyrrolidone solvent.

[0188] An all-solid-state battery was manufactured by using the anode, the solid electrolyte layer of Example 1, and the cathode of Example 1, in the same manner as Example 1.

[0189] (Comparative Example 3)

[0190] LiNi 0.8 Co 0.15 Mn 0.05 O2 positive electrode active material 85 wt%, Li6PS5Cl solid electrolyte 12 wt%, Li 5.5 PS 4.5 Cl 0.75 Br 0.75 A cathode composition was prepared by mixing 1.2 wt% of a (crystalline) additive, 0.5 wt% of a carbon nanotube conductive material, and 1.3 wt% of a binder in an N-methylpyrrolidone solvent. That is, the content of the additive was 10 wt% with respect to 100 wt% of the content of the additive and the solid electrolyte.

[0191] An anode was prepared by carrying out the same procedure as in Example 1, except that the above anode composition was used.

[0192] An all-solid-state battery was manufactured by using the anode, the solid electrolyte layer of Example 1, and the cathode of Example 1, in the same manner as Example 1.

[0193] (Comparative Example 4)

[0194] LiNi 0.8 Co 0.15 Mn 0.05 O2 cathode active material 85 wt%, Li 5.5 PS 4.5 Cl 0.75 Br 0.75An anode composition was prepared by mixing 13.2 wt%, 0.5 wt% carbon nanotube conductive material, and 1.3 wt% binder in an N-methylpyrrolidone solvent.

[0195] An anode was prepared by carrying out the same procedure as in Example 1, except that the above anode composition was used.

[0196] An all-solid-state battery was manufactured by using the anode, the solid electrolyte layer of Example 1, and the cathode of Example 1, in the same manner as Example 1.

[0197] Experimental Example 1) DSC Measurement

[0198] Differential gravimetric analysis (DSC) of the mixture of the Li6PS5Cl solid electrolyte and 75Li2S-25P2S5 additive (glass) used in Example 1 (mixing ratio: 10:1 by weight) was performed using a TA Instruments Discovery DSC 250 instrument to measure the change in heat quantity while increasing the temperature from 40°C to 250°C at a heating rate of 5°C / min. The experimental results are shown in Figure 3.

[0199] The Li6PS5Cl solid electrolyte of Comparative Example 1, the Li6PS5Cl solid electrolyte used in Comparative Example 3, and Li 5.5 PS 4.5 Cl 0.75 Br 0.75 The DSC of a mixture of (crystalline) additives (mixing ratio: 10:1 by weight) was measured using the same method as above. The results are shown in Fig. 5.

[0200] The 75Li2S-25P2S5 additive (glass) of Comparative Example 2 and the Li of Comparative Example 4 5.5 PS 4.5 Cl 0.75 Br 0.75 The DSC of was measured using the same method as above. The results are shown in Fig. 7.

[0201] The all-solid-state batteries prepared in Examples 1 and 2 and Comparative Examples 1 and 3 were charged to 4.25V at 0.1C, and then the batteries were disassembled to obtain the positive electrodes. The DSC of the obtained positive electrodes was measured in the same manner as above. Among the results, the results of Examples 1 and 2 are shown in FIG. 4, and the results of Comparative Examples 1 and 3 are shown in FIG. 6.

[0202] As shown in FIG. 3, the additive of Example 1 exhibited an endothermic peak at approximately 200°C to 250°C. The endothermic peak in FIG. 3 was obtained from the additive of Example 1, and since no endothermic peak appeared in the DSC results of Li6PS5Cl shown in FIG. 5, it can be seen that the endothermic peak in FIG. 3 was obtained from the additive of Example 1. Accordingly, it can be seen that the anodes of Examples 1 and 2 containing this did not exhibit an exothermic peak at 200°C to 250°C, and the exothermic peak that appeared at 350°C to 400°C was also very small.

[0203] As shown in FIG. 5, the Li6PS5Cl of Comparative Example 1 and the Li6PS5Cl solid electrolyte used in Comparative Example 3 and Li 5.5 PS 4.5 Cl 0.75 Br 0.75 It can be seen that the mixture of (crystalline) additives does not exhibit an endothermic peak. Therefore, as shown in FIG. 6, it can be seen that the anodes of Comparative Example 1 and Comparative Example 3 containing this exhibited exothermic peaks at 200°C to 250°C and 350°C to 400°C.

[0204] As shown in FIG. 7, the Li6PS5Cl solid electrolyte of Comparative Example 4 and Li 5.5 PS 4.5 Cl 0.75 Br 0.75 The mixture of (crystalline) additives did not show an endothermic peak, and the 75Li2S-25P2S5 additive (glass) of Comparative Example 2 showed an endothermic peak at about 200°C.

[0205] From these results, it is clearly evident that when an additive exhibiting an endothermic peak at 180°C to 220°C is used in the anode together with a solid electrolyte, the exothermic reaction at 180°C to 220°C is reduced. Therefore, it can be seen that battery stability is greatly improved.

[0206] Experimental Example 2) X-ray Diffraction Evaluation

[0207] X-ray diffraction evaluation was performed on the additive of Example 1 and the additive of Comparative Example 3. The X-ray diffraction evaluation was measured using CuKα rays as the target line, and the monochromator device was removed to improve peak intensity resolution. At this time, the measurement conditions were set to 2θ = 10° to 80°, the scan speed (° / S) to 0.6436, and the step size (° / step) to 0.026° / step.

[0208] The results are shown in FIG. 8. As shown in FIG. 8, the additive of Example 1 did not show peaks at 2θ=29° to 31° and 2θ=31° to 32°, while Comparative Example 3 showed peaks at 2θ=29° to 31° and 2θ=31° to 32°. From these results, it can be seen that the additive of Example 1 is glassy and amorphous, and the additive of Comparative Example 3 is crystalline.

[0209] Although preferred embodiments of the present invention have been described above, the present invention is not limited thereto and can be implemented with various modifications within the scope of the claims, the detailed description of the invention, and the attached drawings, and it is obvious that such modifications also fall within the scope of the present invention.

Claims

1. Sulfide-based solid electrolyte; and A sulfur-containing additive that is glass or glass-ceramic and has an endothermic peak appearing at 180°C to 220°C during differential scanning calorimetry (DSC) measurement. An anode containing 2. In Paragraph 1, An anode in which the content of the sulfur-containing additive is 5% to 31% by weight with respect to 100% by weight of the solid electrolyte and the sulfur-containing additive.

3. In Paragraph 1, An anode in which the content of the sulfur-containing additive is 7% to 31% by weight with respect to 100% by weight of the solid electrolyte and the sulfur-containing additive.

4. In Paragraph 1, The above sulfur-containing additive is an anode that is glass, glass ceramic, or a combination thereof.

5. In Paragraph 1, The above sulfur-containing additives are xLi2S-(100-x)P2S5 (where x is an integer from 50 to 90), xLi2S-(100-x)SiS2 (where x is an integer from 50 to 90), Li2SO4, LiI, LiBr, xLi2S-(100-xy)P2S 5-y P2O5((x is an integer from 50 to 90, and y is an integer from 10 to 30) , y An anode that is GeS2 (y is an integer from 10 to 20), or a combination thereof.

6. In Paragraph 1, The above sulfur-containing additive is an anode of xLi2S-(100-x)P2S5 (where x is an integer from 50 to 90).

7. In Paragraph 1, The above sulfur-containing additive is an anode that is 75Li2S-25P2S5, 70Li2S-30P2S5, 87.5Li2S-12.5P2S5, or a combination thereof.

8. In Paragraph 1, The above sulfur-containing additive is an anode in which no peaks appear at 2θ=28° to 35° and 2θ=15° to 20° when measuring X-ray diffraction peaks.

9. In Paragraph 1, The above sulfur-containing additive is an anode in which, when measuring X-ray diffraction peaks, the background intensity is 20% to 100% relative to 100% of the intensity of the main peak appearing at 2θ=29° to 31°.

10. In Paragraph 1, The above sulfide-based solid electrolyte is an anode that is an argyrodite-type sulfide-based solid electrolyte.

11. In Paragraph 1, The above sulfide-based solid electrolyte is Li2S-P2S5-LiX (where X is a halogen element, e.g., I or Cl), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (m and n are integers greater than or equal to 0 and less than or equal to 12, respectively, and Z is one of Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p and q are integers greater than or equal to 0 and less than or equal to 12, respectively; M is one of P, Si, Ge, B, Al, Ga, and In), Li a M b P c S d A e An anode that is (a, b, c, d, and e are each integers from 0 to 12, provided that a, b, c, d, and e are not all 0, M is Ge, Sn, Si, or a combination thereof, and A is one of F, Cl, Br, or I) or a combination thereof.

12. In Paragraph 1, The above sulfide-based solid electrolyte is Li a M b P c S d A e (a, b, c, d, and e are each integers from 0 to 12, and a, b, c, d, and e are not all 0, M is Ge, Sn, Si, or a combination thereof, and A is one of F, Cl, Br, or I 13. In Paragraph 1, The above-mentioned anode is an anode comprising an anode active material.

14. In Paragraph 1, The anode comprises a current collector; and an anode active material layer located on the current collector, wherein the sulfide-based solid electrolyte and the sulfur-containing additive are included in the anode active material layer, and the anode active material layer comprises an anode active material.

15. In Paragraph 14, A cathode having a content of the sulfur-containing additive of 0.01% to 50% by weight relative to 100% by weight of the cathode active material layer.

16. The positive electrode of any one of paragraphs 1 to 15; cathode; and A solid electrolyte layer located between the anode and the cathode. All-solid-state secondary battery including

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