Solid electrolyte membrane, manufacturing method therefor, and all-solid-state battery comprising same

Abstract

The present invention relates to a solid electrolyte membrane, a manufacturing method therefor, and an all-solid-state battery comprising same, and, specifically, to a solid electrolyte membrane, a manufacturing method therefor, and an all-solid-state battery comprising same, the solid electrolyte membrane being capable of suppressing the vertical growth of lithium dendrites, thereby having significantly improved high-rate characteristics.

Description

Solid electrolyte membrane, method of manufacturing the same, and all-solid-state battery including the same

[0001] The present invention relates to a solid electrolyte membrane, a method for manufacturing the same, and an all-solid-state battery including the same. Specifically, it relates to a solid electrolyte membrane capable of improving high-rate characteristics by suppressing the vertical growth of lithium dendrites, a method for manufacturing the same, and an all-solid-state battery including the same.

[0002] Lithium-ion batteries have currently reached their theoretical capacity limit and also present safety issues due to the use of flammable organic liquid electrolytes. To overcome these challenges, all-solid-state batteries are garnering attention as the next generation of batteries. An all-solid-state battery is a next-generation rechargeable battery that replaces the conventional liquid electrolyte interposed between the anode and cathode with a solid electrolyte. All-solid-state batteries are expected to resolve the safety issues associated with existing lithium-ion batteries. Furthermore, because all-solid-state batteries can utilize lithium metal as the cathode, they can achieve higher energy density compared to conventional lithium-ion batteries.

[0003] However, all-solid-state batteries have a problem in that it is difficult to form a stable interface because the anode layer and the electrolyte layer (separator layer or electrolyte membrane) form a solid-solid interface. In particular, compared to liquid electrolyte systems, lithium dendrites can easily form and grow at the interface between the anode layer and the electrolyte layer in all-solid-state battery systems, which has resulted in difficulties in operating at high current densities. Therefore, a design strategy capable of suppressing lithium dendrite growth is required for the stable operation of all-solid-state batteries.

[0004] As one of the solid electrolyte design strategies capable of inhibiting the growth of lithium dendrites, the addition of lithium dendrite-inhibiting materials has been proposed. These materials operate through a mechanism in which they inhibit further growth via electrochemical reactions upon contact with lithium dendrites generated within the battery, or physically block growth through high mechanical strength. As lithium dendrite-inhibiting materials, forms in which metal salts in the form of hydrates, such as HAuCl4·3H2O, or metal particle-based materials are inserted into the solid electrolyte layer have been proposed. However, hydrates cannot be used with sulfide-based solid electrolytes because, when used together, moisture chemically decomposes the electrolyte, generating byproducts with low ionic conductivity (such as Li2S, Li3P, and LiCl) and hydrogen sulfide (H2S) gas. Additionally, metal particles are difficult to use with sulfide-based solid electrolytes because they react to form metal sulfides.

[0005] Accordingly, there is a need to develop other technologies that can inhibit lithium dendrite growth.

[0006] The present invention was devised to solve the problems of the all-solid-state battery described above, and the problem to be solved by the present invention is to provide a solid electrolyte membrane in which a lithium dendrite inhibitory material exists in a physically mixed state without causing chemical side reactions with the sulfide-based solid electrolyte, unlike conventional metal salts and metal particles in the form of hydrates.

[0007] In addition, another problem to be solved by the present invention is to provide a solid electrolyte membrane with significantly improved battery performance under high rate conditions.

[0008] Another problem to be solved by the present invention is to provide a method for manufacturing a solid electrolyte membrane with excellent stability and improved high-rate characteristics.

[0009] Another problem to be solved by the present invention is to provide an all-solid-state battery with excellent stability and improved high-rate characteristics.

[0010] Other objects, specific advantages, and novel features of the present invention will become more apparent from the following detailed description and preferred embodiments in conjunction with the accompanying drawings.

[0011] To solve the aforementioned technical problem, the present invention provides a solid electrolyte membrane comprising a sulfide-based solid electrolyte; and red phosphorus particles dispersed within the sulfide-based solid electrolyte.

[0012] In one embodiment of the present invention, the sulfide-based solid electrolyte may include an azirodite-type sulfide represented by the following chemical formula 1.

[0013] [Chemical Formula 1]

[0014] (Li a M 1 b M 2 c )(P d M 3 e )(S f M 4 g )X h

[0015] In the above chemical formula 1,

[0016] 4≤a≤8 and,

[0017] M 1 is Mg, Cu, Ag, or a combination thereof, 0≤b<0.5, and

[0018] M 2 is Na, K, or a combination thereof, 0≤c<0.5, and

[0019] M 3 is Sn, Zn, Si, Sb, Ge, or a combination thereof, and 0 <d<4, 0≤e<1 이고,

[0020] M 4 is O, SO n, or a combination thereof, 1.5≤n≤5, 3≤f≤12, 0≤g<2, and

[0021] X is F, Cl, Br, I, or a combination thereof, and 0≤h≤2.

[0022] In one embodiment of the present invention, the red phosphorus particles may be included in an amount of 2 to 20 parts by weight per 100 parts by weight of the sulfide-based solid electrolyte.

[0023] In one embodiment of the present invention, the red phosphorus particles may be included in an amount of 7 to 9 parts by weight per 100 parts by weight of the sulfide-based solid electrolyte.

[0024] In one embodiment of the present invention, the red phosphorus particles may have an average particle size of 10 nm to 10 μm.

[0025] In one embodiment of the present invention, the solid electrolyte membrane may comprise: a first solid electrolyte layer comprising the sulfide-based solid electrolyte; and a second solid electrolyte layer formed on the first solid electrolyte layer and comprising the sulfide-based solid electrolyte and red phosphorus particles dispersed within the sulfide-based solid electrolyte.

[0026] In one embodiment of the present invention, the first solid electrolyte layer comprises red phosphorus particles, and the red phosphorus particle content of the first solid electrolyte layer may be less than the red phosphorus particle content of the second solid electrolyte layer.

[0027] In one embodiment of the present invention, the ratio of red phosphorus particle content between the first solid electrolyte layer and the second solid electrolyte layer may be 1:3 to 1:10. In one embodiment of the present invention, the red phosphorus particles of the second solid electrolyte layer may have a concentration gradient.

[0028] In one embodiment of the present invention, the first solid electrolyte layer and the second solid electrolyte layer may have a thickness ratio of 5:1 to 15:1.

[0029] The present invention provides a method for manufacturing a solid electrolyte membrane comprising: (S1) a step of pulverizing red phosphorus particles; and (S2) a step of mixing and pressurizing a sulfide-based solid electrolyte and the pulverized red phosphorus particles.

[0030] In one embodiment of the present invention, after step (S2), the method may further include: (S3) a step of press-molding a sulfide-based solid electrolyte; and (S4) a step of placing a solid electrolyte membrane formed in step (S2) on top of the sulfide-based solid electrolyte formed in step (S3) and press-molding it.

[0031] The present invention also provides an all-solid-state battery comprising an anode; a cathode; and a solid electrolyte membrane interposed between the anode and the cathode and according to the present invention.

[0032] The solid electrolyte membrane according to the present invention can suppress the vertical growth of lithium dendrites and prevent internal short circuits by forming lithium phosphide (Li3P) through an electrochemical reaction when it comes into contact with red phosphorus particles dispersed in a sulfide-based solid electrolyte during lithium dendrite growth.

[0033] An all-solid-state battery comprising a solid electrolyte membrane according to the present invention can provide an all-solid-state battery with significantly improved high-rate characteristics and superior performance compared to conventional technology.

[0034] FIG. 1 is a schematic diagram illustrating the principle of a solid electrolyte layer suppressing the vertical growth of lithium dendrites according to a preferred embodiment of the present invention.

[0035] Figure 2 is an SEM image of red phosphorus particles finely ground by a ball mill.

[0036] FIGS. 3a and 3b are SEM and EDS images of the top (Fig. 3a) and cross-section (Fig. 3b) of a solid electrolyte layer according to a preferred embodiment of the present invention.

[0037] Figures 4a and 4b show the XRD (Figure 3a) and Raman spectrum (Figure 3b) analysis results of a solid electrolyte layer (Example 4), Li6PS5Cl (LPSCl), and red phosphorus (Red P) according to a preferred embodiment of the present invention.

[0038] FIG. 5 is a graph comparing the electrochemical impedance spectroscopic (EIS) analysis results of a solid electrolyte membrane containing a solid electrolyte according to Example 4 and Comparative Example 1 of the present invention.

[0039] FIGS. 6a and 6b are graphs comparing the voltage profile (Fig. 6a) and critical electrodeposition capacity (Fig. 6b) in a constant current experiment of a solid electrolyte membrane containing a solid electrolyte according to Manufacturing Examples 1 to 5 and Comparative Manufacturing Example 1 of the present invention.

[0040] Figures 7a and 7b respectively show a comparison of the results of measuring the critical current density of an all-solid-state battery containing a solid electrolyte according to Comparative Example 1 (Fig. 7a) and Comparative Example 3 (Fig. 7b).

[0041] FIGS. 8a to 8c are graphs evaluating the cycle performance of an all-solid-state battery containing a solid electrolyte membrane according to Preparation Example 3 under operating conditions of 5 mA / cm² (Fig. 8a), 10 mA / cm² (Fig. 8b), and 20 mA / cm² (Fig. 8c).

[0042] FIG. 9 is a schematic diagram illustrating a method for conducting an experiment to elucidate the lithium dendrite suppression mechanism of a solid electrolyte membrane according to a preferred embodiment of the present invention.

[0043] Figures 10a and 10b show the results of XPS analysis at the SE / SE interface after electrodeposition was performed on the all-solid-state batteries of Comparative Example 2 (Fig. 10a) and Example 7 (Fig. 10b).

[0044] Figures 11a and 11b show the XPS analysis results at the Li / SE interface of Comparative Example 2 (Fig. 10a) and Example 7 (Fig. 10b).

[0045] Figure 12 is a graph showing the results of evaluating the rate characteristics of an all-solid-state battery according to Manufacturing Example 7.

[0046] Figure 13 is a graph showing the high-rate cycle performance evaluation results of an all-solid-state battery according to Manufacturing Example 7.

[0047] In this specification, singular expressions include plural expressions unless the context clearly indicates otherwise. For example, one or more current collectors and composite layers may be provided.

[0048] In this specification, the terms “comprise” and / or “comprising” specify the presence of the mentioned features, steps, numbers, actions, parts, elements, and / or groups thereof, and do not exclude the presence or addition of one or more other features, steps, numbers, actions, parts, elements, and / or groups thereof.

[0049] In this specification, expressions such as "first," "second," "first," "second," "(S1)," "(S2)," etc. may modify various components regardless of order and / or importance and do not limit such components. These expressions may be used to distinguish one component from another. For example, without departing from the scope of the present disclosure, the first component may be named the second component, and similarly, the second component may be renamed the first component.

[0050] In this specification, "at least one of a, b and c" may include a, b, or c alone, or two or more combinations selected from the group consisting of a, b, and c.

[0051] Where various embodiments are described in this specification, each embodiment may be combined unless specifically stated otherwise. In this case, the effects of the present invention may be defined as including effects derived from each embodiment and effects resulting from the organic combination of each embodiment. For example, even if embodiments 1 and 2 are described independently in this specification, unless the context clearly indicates otherwise, embodiments 1 and 2 may be organically combined with each other, and the effects of the present invention may include effects resulting from the combination of embodiments 1 and 2.

[0052] In this specification, a range of numerical values ​​indicated by the term 'to' represents a range of numerical values ​​that includes the values ​​listed before and after the term as the lower and upper limits, respectively. If multiple numerical values ​​are disclosed as the upper and lower limits of an arbitrary numerical range, the range of numerical values ​​disclosed in this specification may be understood as a range of arbitrary numerical values ​​in which any one of the multiple lower limits and any one of the multiple upper limits are respectively the lower limit and upper limit. For example, if the specification states a to b or c to d, it may be understood as stating a to b, a to d, c to d, or c to b.

[0053] In this specification, terms such as “about” or “substantially” refer to a reasonable amount of variation of a term modified so as not to significantly alter the final result. Such terms may be interpreted to include a variation of at least ±5% or at least ±10% to the extent that the variation does not alter or invalidate the meaning of the word.

[0054] In this specification, "layer" or "membrane" may include cases where, when observing the region in which the layer or membrane exists, it is formed over the entire region, or cases where it is formed only in a part of the region. For example, the surface of the layer or membrane may be defined as having a flat shape, a non-flat shape, and combinations thereof; or a continuous shape, a discontinuous shape, and combinations thereof. For example, when another member is composed of a layer or membrane directly on top of a member, the coverage of the other member on the surface of the member may be defined as 1% or more, 5% or more, 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 85% or more, 90% or more, 95% or more, or 99% or more. For example, when multiple particles form a clustered structure, it can also be defined as a "layer or membrane."

[0055] In this specification, when another member is placed directly on top of one member, it may be defined that no member is interposed between the one member and the other member.

[0056] The configuration of the present invention will be described in more detail below with reference to the attached drawings.

[0057] 1. Solid electrolyte membrane

[0058] The present invention provides a solid electrolyte membrane comprising a sulfide-based solid electrolyte; and red phosphorus particles dispersed within the sulfide-based solid electrolyte.

[0059] The above sulfide-based solid electrolyte may include an argyrodite-type sulfide.

[0060] Sulfide-based solid electrolytes containing azirodite-type sulfides have an ionic conductivity of 10 at room temperature, which is the same as that of typical liquid electrolytes. -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.

[0061] The above sulfide-based solid electrolyte may include, for example, a compound represented by Chemical Formula 1 below.

[0062] [Chemical Formula 1]

[0063] (Li a M 1 b M 2 c )(P d M 3 e )(S f M 4 g )X h

[0064] In the above chemical formula 1, 4≤a≤8, and M 1 is Mg, Cu, Ag, or a combination thereof, 0≤b<0.5, and M 2 is Na, K, or a combination thereof, 0≤c<0.5, and M 3 is Sn, Zn, Si, Sb, Ge, or a combination thereof, and 0 <d<4, 0≤e<1 이고, M 4 is O, SO n , or a combination thereof, 1.5≤n≤5, 3≤f≤12, 0≤g<2, X is F, Cl, Br, I, or a combination thereof, and 0≤h≤2.

[0065] For example, in Chemical Formula 1, a halide element (X) may be necessarily included, in which case 0 <h≤2로 표시될 수 있다. 일 예로 화학식 1에 M 1 An element may be required, in which case 0 <b<0.5로 표시될 수 있다. 화학식 1에서 M3 can be understood as an element substituted in the P position, and 0 <e<1일 수 있다. 화학식 1에서 M 4 is substituted in the S position, for example, 0 <g<2일 수 있으며 S의 비율인 f는 예를 들어 3≤f≤7일 수 있다. M 4 ga SO n In the case of SO n It can be, for example, S4O6, S3O6, S2O3, S2O4, S2O5, S2O6, S2O7, S2O8, SO4, or SO5, and as an example, it can be SO4.

[0066] For example, in Chemical Formula 1, a+b+c+h=7, d+e=1, and f+g+h=6.

[0067] As a specific example, azirodite-type sulfide-based solid electrolytes include Li3PS4 and Li7P3S 11 , Li7PS6, Li6PS5Cl(LPSCl), Li6PS5Br, Li 5.8 PS 4.8 Cl 1.2 , Li6.2PS 5.2 Br 0.8 , 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 5.72Na 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.

[0068] An azirodite-type sulfide-based solid electrolyte can be prepared by mixing, for example, lithium sulfide and phosphorus sulfide, and optionally lithium halide. After mixing these, heat treatment may be performed. The heat treatment may include, for example, two or more heat treatment steps. Here, preparing an azirodite-type sulfide-based solid electrolyte may include, for example, a first heat treatment in which raw materials are mixed and calcined at 120°C to 350°C, and a second heat treatment in which the result of the first heat treatment is mixed again and calcined at 350°C to 800°C.

[0069] The average particle size (D50) of the sulfide-based solid electrolyte particles may be, for example, 0.1 μm to 5.0 μm or 0.1 μm to 3.0 μm, and may be fine particles of 0.1 μm to 1.9 μm or coarse particles of 2.0 μm to 5.0 μm. The sulfide-based solid electrolyte particles may be a mixture of fine particles with an average particle size of 0.1 μm to 1.9 μm and coarse particles with an average particle size of 2.0 μm to 5.0 μm. The average particle size of the sulfide-based solid electrolyte particles may be measured using electron microscope images, for example, by measuring the size (diameter or length of the major axis) of about 20 particles in a scanning electron microscope image to obtain a particle size distribution and calculating D50 from it.

[0070] The solid electrolyte membrane of the present invention can suppress the growth of lithium dendrites by generating lithium phosphide (Li3P) byproducts when it comes into contact with lithium dendrites in which red phosphorus particles grow within the sulfide-based solid electrolyte, thereby preventing internal short circuits in the battery caused by lithium dendrites.

[0071] FIG. 1 is a schematic diagram illustrating a lithium dendrite suppression mechanism of an all-solid-state battery including a solid electrolyte membrane according to a preferred embodiment of the present invention. Referring to FIG. 1, the solid electrolyte membrane includes red phosphorus particles dispersed in a sulfide-based solid electrolyte, and when lithium dendrites grown from the negative electrode layer come into contact with the red phosphorus particles, lithium phosphide is formed at the contact interface, thereby changing the growth direction of the lithium dendrites.

[0072] In order to produce this effect, red phosphorus particles need to be uniformly and sufficiently dispersed within the sulfide-based solid electrolyte. If the content of red phosphorus particles is insufficient, there is a possibility that the lithium dendrites may not come into contact with the red phosphorus particles until a short circuit occurs; if the content of red phosphorus particles is excessive, they may act as a resistive element, potentially degrading the electrochemical performance of the all-solid-state battery, so appropriate control of the content is necessary.

[0073] FIGS. 3a and FIGS. 3b are SEM images and EDS of the top and cross-section of a solid electrolyte membrane according to a preferred embodiment of the present invention, respectively. Referring to FIG. 3b, it can be seen that red phosphorus particles are uniformly dispersed throughout the entire solid electrolyte membrane.

[0074] Specifically, the red phosphorus particles may be included in an amount of 2 to 20 parts by weight per 100 parts by weight of the solid electrolyte membrane. More preferably, the red phosphorus particles may be included in an amount of 7 to 9 parts by weight per 100 parts by weight of the solid electrolyte membrane.

[0075] If the content of the red phosphorus particles is less than 6 parts by weight, the effect of inhibiting the vertical growth of lithium dendrites may not be sufficient. However, if the content of the red phosphorus particles exceeds 20 parts by weight, there is a problem in that the overpotential increases during the electrodeposition process and the critical electrodeposition capacity decreases due to the red phosphorus having low ion conductivity. In addition, when the content of the red phosphorus particles satisfies the range of 7 to 9 parts by weight, a high critical electrodeposition capacity can be achieved while effectively inhibiting the growth of lithium dendrites.

[0076] In a preferred embodiment of the present invention, the red phosphorus particles may have an average particle size of 10 nm to 10 μm, preferably 10 nm to 1 μm, and more preferably 100 nm to 1 μm. If the average particle size of the red phosphorus particles is less than 10 nm, the effect of shielding and inhibiting the growth of lithium dendrites may not be sufficient, and conversely, if it exceeds 10 μm, there may be a problem in that the ionic conductivity of the solid electrolyte membrane including the solid electrolyte membrane decreases, thereby reducing the critical electrodeposition capacity.

[0077] In a preferred embodiment of the present invention, the solid electrolyte membrane comprises a first solid electrolyte layer including the sulfide-based solid electrolyte; and

[0078] It may include a second solid electrolyte layer formed on the first solid electrolyte layer and comprising the sulfide-based solid electrolyte and red phosphorus particles dispersed within the sulfide-based solid electrolyte.

[0079] A solid electrolyte membrane composed of multiple layers in this way has the effect of inhibiting the growth of lithium dendrites while minimizing the content of red phosphorus particles.

[0080] In a preferred embodiment of the present invention, the first solid electrolyte layer and the second solid electrolyte layer may have a thickness ratio of 5:1 to 15:1.

[0081] In a preferred embodiment of the present invention, the solid electrolyte film may be positioned such that the second solid electrolyte layer contacts the cathode in order to suppress lithium dendrites growing from the cathode.

[0082] In another preferred embodiment of the present invention, the first solid electrolyte layer may comprise the sulfide-based solid electrolyte and red phosphorus particles dispersed within the sulfide-based solid electrolyte. In this case, the red phosphorus particle content of the first solid electrolyte layer may be less than the red phosphorus particle content of the second solid electrolyte layer.

[0083] Specifically, the red phosphorus particle content of the first solid electrolyte layer and the red phosphorus particle content of the second solid electrolyte layer may have a ratio of 1:3 to 1:10 based on the content per 100 parts by weight of the sulfide-based solid electrolyte. When the ratio of the red phosphorus particle content of the first solid electrolyte layer and the second solid electrolyte layer is 1:3 to 1:10, lithium dendrite growth can be effectively suppressed with a solid electrolyte film having a minimum amount of red phosphorus particles and a minimum thickness.

[0084] In addition, in another embodiment of the present invention, the solid electrolyte membrane may have a concentration gradient in which the content of red phosphorus particles is high on one surface of the solid electrolyte membrane and decreases towards the opposite surface. In particular, it is preferable that the second solid electrolyte layer has a concentration gradient. In this case, preferably, the content of red phosphorus particles may be high on one surface in the cathode direction and low on one surface in the anode direction.

[0085] The above solid electrolyte membrane is

[0086] (S1) A step of pulverizing red phosphorus particles; and

[0087] (S2) A step of mixing and press-molding the sulfide-based solid electrolyte and the finely divided red phosphorus particles; can be manufactured.

[0088] In a preferred embodiment of the present invention,

[0089] (S3) A step of press-molding a sulfide-based solid electrolyte; and

[0090] (S4) may further include the step of placing the solid electrolyte membrane formed in step (S2) on top of the sulfide-based solid electrolyte formed in step (S3) and pressurizing it.

[0091] In the above step (S4), the sulfide-based solid electrolyte formed in step (S3) forms the first solid electrolyte layer, and the solid electrolyte film formed in step (S2) forms the second solid electrolyte layer.

[0092] In the above steps (S2) and (S4), the pressure molding method may be selected from among methods commonly used in the relevant technical field.

[0093] Specifically, after pressurizing with a pressure of 100 MPa to 200 MPa in the first step, a second molding pressure of 300 MPa to 500 MPa can be applied to perform a second molding, but this is not limited to that.

[0094] bookbinder

[0095] The solid electrolyte membrane of the present invention may further include a binder. The binder is, for example, nitrile-butadiene rubber, hydrogenated nitrile-butadiene rubber, styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile-butadiene rubber, acrylic rubber, butyl rubber, fluororubber, natural rubber, polydimethylsiloxane, polyethylene oxide, polyvinylpyrrolidone, polyvinylpyridine, chlorosulfonated polyethylene, polyvinyl alcohol, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, polyamideimide, polyimide, poly(meth)acrylate, polyacrylonitrile, polystyrene, polyurethane, copolymers thereof, Or it may include a combination of these.

[0096] The binder may be included in an amount of 0.1 to 3 parts by weight per 100 parts by weight of the solid electrolyte membrane, for example, 0.5 to 2 parts by weight, or 0.5 to 1.5 parts by weight. When the binder is included within the above range, the components within the solid electrolyte membrane can be well bonded without lowering the ionic conductivity of the solid electrolyte, thereby improving the durability and reliability of the battery.

[0097] Other ingredients

[0098] The solid electrolyte membrane may include an oxide-based inorganic solid electrolyte in addition to a sulfide-based solid electrolyte. The oxide-based inorganic 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), Pb1-x La x Zr 1-y Ti y O3(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.

[0099] The solid electrolyte membrane may further include, for example, a halide-based solid electrolyte. The halide-based solid electrolyte contains a halogen element as a main component, and the ratio of the halide element to all elements constituting the solid electrolyte may be 50 mol% or more, 70 mol% or more, 90 mol% or more, or 100 mol%. For example, the halide-based solid electrolyte may not contain a sulfur element.

[0100] The halide-based solid electrolyte may contain a lithium element, a metal element other than lithium, and a halogen element. The metal element other than lithium may be Al, As, B, Bi, Ca, Cd, Co, Cr, Fe, Ga, Hf, In, Mg, Mn, Ni, Sb, Sc, Sn, Ta, Ti, Y, Zn, Zr, or a combination thereof. The halogen element may be F, Cl, Br, I, or a combination thereof, and for example, may be Cl, Br, or a combination thereof. The halide-based solid electrolyte is, for example, Li a It can be represented as M1X6 (M is Al, As, B, Bi, Ca, Cd, Co, Cr, Fe, Ga, Hf, In, Mg, Mn, Ni, Sb, Sc, Sn, Ta, Ti, Y, Zn, Zr, or a combination thereof, X is F, Cl, Br, I, or a combination thereof, and 2≤a≤3). The above halide-based solid electrolyte is, for example, Li2ZrCl6, Li 2.7 Y 0.7 Zr 0.3 Cl6, Li 2.5 Y 0.5 Zr 0.5 Cl6, Li 2.5 In 0.5 Zr 0.5 Cl6, Li2In 0.5 Zr 0.5 Cl6, Li3YBr6, Li3YCl6, Li3YBr2Cl4, Li3YbCl6, Li 2.6 Hf 0.4 Yb 0.6 It may include Cl6, or a combination thereof, but is not limited thereto.

[0101] The solid electrolyte membrane may optionally further include an alkali metal salt, and / or an ionic liquid, and / or a conductive polymer.

[0102] The above alkali metal salt may be, for example, a lithium salt. The content of the lithium salt in the above 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.

[0103] Lithium salts may be applied without limitation of type and may include, for example, LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiSCN, LiN(CN)2, lithium bis(oxalateto)borate (LiBOB), lithium difluoro(oxalateto)borate (LiDFOB), lithium difluorobis(oxalateto)phosphate (LiDFBP), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(pentafluoroethanesulfonyl)imide (LiBETI), lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, or combinations thereof.

[0104] For example, the above lithium salt may be an imide-based lithium salt such as LiTFSI, LiFSI, LiBETI, or a combination thereof. The imide-based lithium salt can maintain or improve ionic conductivity by appropriately maintaining chemical reactivity with the ionic liquid.

[0105] Ionic liquids are salts or room temperature molten salts that have a melting point below room temperature, are in a liquid state at room temperature, and consist only of ions.

[0106] The ionic liquid comprises a) one or more cations selected from ammonium, pyrrolidinium, pyridinium, pyrimidinium, imidazolium, piperidinium, pyrazolium, oxazolium, pyridazinium, phosphonium, sulfonium, triazolium, 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.

[0107] 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.

[0108] The weight ratio of the solid electrolyte to the ionic liquid in the above solid electrolyte membrane 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 membrane 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 secondary battery can be improved.

[0109] 2. Secondary battery

[0110] The present invention also provides an all-solid-state battery comprising an anode; a cathode; and a solid electrolyte membrane interposed between the anode and the cathode.

[0111] cathode

[0112] The above-mentioned cathode comprises a current collector and a cathode active material layer located on the current collector. The cathode active material layer comprises a cathode active material and may further comprise a binder and / or a conductive material, and optionally may comprise the aforementioned solid electrolyte.

[0113] The above-mentioned negative electrode active material includes 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.

[0114] 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.

[0115] As the above lithium metal alloy, an alloy of a metal selected from the group consisting of lithium, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn may be used.

[0116] 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. xExamples of the above Sn-based negative electrode active materials include (0 < x < 2), Si-Q alloy (where Q is an element selected from the group consisting of alkali metals, alkaline earth metals, group 13 elements, group 14 elements, group 15 elements, group 16 elements, transition metals, rare earth elements, and combinations thereof, and is not Si), Sn, SnO2, Sn-R alloy (where R is an element selected from the group consisting of alkali metals, alkaline earth metals, group 13 elements, group 14 elements, group 15 elements, group 16 elements, transition metals, rare earth elements, and combinations thereof, and is not Sn), and at least one of these may be mixed with SiO2. The above elements Q and R may be selected from the group consisting of 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, and combinations thereof.

[0117] The above-mentioned cathode active material may include silicon-carbon composite particles. The average particle size (D50) of the silicon-carbon composite particles may be, for example, 0.5 μm to 20 μm. The average particle size (D50) is measured by a particle size analyzer and refers to the diameter of a particle whose cumulative volume in the particle size distribution is 50 volume%. With respect to 100 weight% of the silicon-carbon composite particles, silicon may be included in an amount of 10 weight% to 60 weight% and carbon may be included in an amount of 40 weight% to 90 weight%. The silicon-carbon composite particles may include, for example, a core containing silicon particles and a carbon coating layer located on the surface of the core. The average particle size (D50) of the silicon particles in the core may be 10 nm to 1 μm, or 10 nm to 200 nm. The silicon particles may exist as silicon alone, in the form of a silicon alloy, or in an oxidized form. The oxidized form of silicon is SiO₂. x (0 <x<2)로 표시될 수 있다. 또한, 상기 탄소 코팅층의 두께는 약 5 nm 내지 100 nm일 수 있다.

[0118] The silicon-carbon composite particles may comprise a core containing silicon particles and crystalline carbon, and a carbon coating layer located on the surface of the core containing amorphous carbon. For example, in the silicon-carbon composite particles, the amorphous carbon may not be present in the core but only in the carbon coating layer. The crystalline carbon may be artificial graphite, natural graphite, or a combination thereof, and the amorphous carbon may be formed from coal-based pitch, mesophase pitch, petroleum-based pitch, coal-based oil, petroleum-based heavy oil, or a polymer resin (phenol resin, furan resin, polyimide resin, etc.). In this case, the content of the crystalline carbon may be 10% to 70% by weight and the content of the amorphous carbon may be 20% to 40% by weight with respect to 100% by weight of the silicon-carbon composite particles.

[0119] The core of the silicon-carbon composite particle may include a void in the central portion. The radius of the void may be 30% to 50% of the radius of the silicon-carbon composite particle.

[0120] The aforementioned silicon-carbon composite particles effectively suppress problems such as volume expansion, structural collapse, or particle fragmentation due to charging and discharging, thereby preventing the interruption of conductive paths, enabling high capacity and high efficiency, and making them advantageous for use under high voltage or high-speed charging conditions.

[0121] 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. When the Si-based negative electrode active material or Sn-based negative electrode active material and the carbon-based negative electrode active material are mixed and used, the mixing ratio may be 1:99 to 90:10 by weight.

[0122] 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.

[0123] The above-mentioned negative electrode active material layer further comprises a binder and may optionally further comprise a conductive material. The content of the binder in the above-mentioned negative electrode active material layer may be 1% to 5% by weight relative to the total weight of the negative electrode active material layer. Additionally, when further comprising a conductive material, the above-mentioned 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.

[0124] 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. As the binder, a water-insoluble binder, a water-soluble binder, or a combination thereof may be used.

[0125] Examples of the above-mentioned water-insoluble binders include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, a polymer containing ethylene oxide, an ethylene propylene copolymer, polystyrene, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, or a combination thereof.

[0126] Examples of the above water-soluble binders include rubber-based binders or polymer resin binders. The 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 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.

[0127] When a water-soluble binder is used as the above-mentioned cathode binder, a cellulose-based compound capable of imparting viscosity as a type of thickener may be further included. As this 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 content of such a thickener may be 0.1 to 3 parts by weight per 100 parts by weight of the cathode active material.

[0128] The above conductive material is used to impart conductivity to the electrode, and any electronically conductive material that does not cause chemical changes can be used in the battery being constructed. Examples include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, carbon nanotube; 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 conductive materials including mixtures thereof.

[0129] The above-mentioned cathode current collector may be selected from the group consisting of copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and combinations thereof.

[0130] As another example, the negative electrode for an all-solid-state secondary battery may be a precipitation type negative electrode. The precipitation type negative electrode may refer to a negative electrode that does not contain a negative electrode active material during battery assembly, but in which lithium metal, etc. is precipitated or electrodeposited on the negative electrode during battery charging, and which acts as the negative electrode active material.

[0131] anode

[0132] The above-mentioned positive electrode comprises a current collector and a positive electrode active material layer located on the current collector, and the positive electrode active material layer comprises a positive electrode active material and a solid electrolyte and may optionally comprise a binder and / or a conductive material. In this case, the positive electrode active material layer may comprise the aforementioned solid electrolyte.

[0133] The above positive electrode active material may be a metal oxide containing lithium capable of electrochemically inserting or extracting lithium by an oxidation-reduction reaction.

[0134] For example, the above-mentioned positive electrode active material may include a lithium transition metal oxide. The above-mentioned lithium transition metal oxide is, for example, Li x1CoO2(0.5≤x1≤1.3), Li x2 NiO2(0.5≤x2≤1.3), Li x3 MnO2(0.5≤x3≤1.3), Li x4 Mn2O4(0.5≤x4≤1.3), Li x5 (Ni a1 Co b1 Mn c1 )O2(0.5≤x5≤1.3, 0 <a1<1, 0<b1<1, 0<c1<1, a1+b1+c1=1), Li x6 Ni 1-y1 Co y1 O2(0.5≤x6≤1.3, 0 <y1<1), Li x7 Co 1-y2 Mn y2 O2(0.5≤x7≤1.3, 0≤y2<1), Li x8 Ni 1-y3 Mn y3 O2(0.5≤x8≤1.3, 0≤y3<1), Li x9 (Ni a2 Co b2 Mn c2 )O4(0.5≤x9≤1.3, 0 <a2<2, 0<b2<2, 0<c2<2, a2+b2+c2=2), Li x10 Mn 2-z1 Ni z1 O4(0.5≤x10≤1.3, 0 <z1<2), Li x11 Mn 2-z2 Co z2 O4(0.5≤x11≤1.3, 0 <z2<2), Li x12 CoPO4 (0.5 ≤ x 12 ≤ 1.3) and Li x13 It may be one or more selected from the group consisting of FePO4 (0.5≤x13≤1.3).

[0135] For example, 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).

[0136] The average particle size (D50) of the above-mentioned positive active material may be 1 μm to 25 μm, for example, 3 μm to 25 μm, 1 μm to 20 μm, 1 μm to 18 μm, 3 μm to 15 μm, or 5 μm to 15 μm. As an example, the above-mentioned positive active material may include small particles with an average particle size (D50) of 1 μm to 9 μm and large particles with an average particle size (D50) of 10 μm to 25 μm. A positive active material having such a particle size range can be harmoniously mixed with other components within the positive active material layer and can achieve high capacity and high energy density.

[0137] 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 single particles. In addition, the above positive active material may be spherical or have a shape close to spherical, or may be polyhedral or irregular in shape.

[0138] In a preferred embodiment of the present invention, the anode may further include a conductive material. For example, the conductive material can improve conductivity between anode active material particles or with the anode current collector in the anode and prevent the binder from acting as an insulator. The conductive material may be, for example, a mixture of one or more conductive materials selected from the group consisting of graphite, carbon black, carbon fiber, metal fiber, metal powder, conductive whiskers, conductive metal oxide, activated carbon, and polyphenylene derivatives; more specifically, it may be a mixture of one or more conductive materials selected from the group consisting of natural graphite, artificial graphite, Super-P, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, Denka black, aluminum powder, nickel powder, zinc oxide, potassium titanate, and titanium oxide.

[0139] In a preferred embodiment of the present invention, the anode may further include a binder. The above binder is, for example, poly(vinylidene fluoride co-hexafluoropropylene), poly(vinylidene fluoride-co-trichloroethylene), poly(methylmethacrylate), poly(ethylhexylacrylate), poly(butylacrylate), poly(acrylonitrile), poly(vinylpyrrolidone), poly(vinyl acetate), ethylene vinyl acetate copolymer (poly(ethylene-co-vinyl acetate)), poly(ethylene oxide), polyacrylate, cellulose acetate, cellulose acetate It may be butyrate (cellulose acetate butyrate), cellulose acetate propionate, cyano ethyl pullulan, cyano ethyl poly(vinyl alcohol)), cyano ethylcellulose, cyano ethylsucrose, pullulan, styrene-butadiene rubber, and carboxyl methyl cellulose, but is not limited thereto.

[0140] The above anode may further include a current collector. In a preferred embodiment of the present invention, the current collector may include SUS, aluminum, nickel, iron, titanium, carbon, etc.

[0141] Hereinafter, specific examples and experimental results will be cited to provide a detailed explanation of the effects of the present invention. The following examples are merely illustrative to help understand the embodiments of the present invention and do not limit the scope of the present invention. Readers of this specification should understand that a person skilled in the art may implement the present invention by adding other components or deleting or substituting non-essential components, excluding the essential components of the present invention, and that such implementations are easily derived from the description in this specification and are also within the scope of the present invention.

[0142] <Example>

[0143] Example 1

[0144] Balls and red phosphorus particles were mixed in a weight ratio of 10:1, and the red phosphorus particles were pulverized by performing a dry ball mill at a rotation speed of 350 rpm for about 24 hours. The average particle size of the pulverized red phosphorus particles was measured to be about 0.1 to 1 μm.

[0145] A solid electrolyte was prepared by mixing 0.975 g of Li6PS5Cl (LPSCl), an azirodite-type sulfide-based solid electrolyte, with 0.025 g of the finely pulverized red phosphorus particles.

[0146] After filling 0.3 g of the above solid electrolyte into a mold, a first pressurization pressure of about 145 MPa and a second pressurization pressure of about 380 MPa were applied to form a solid electrolyte membrane in the form of a pellet.

[0147] Example 2

[0148] The procedure was carried out in the same manner as Example 1, except that the amount of mixture of LPSCl and finely pulverized red phosphorus particles was adjusted to 0.95 g and 0.05 g, respectively.

[0149] Example 3

[0150] The procedure was carried out in the same manner as Example 1, except that the amount of mixture of LPSCl and finely pulverized red phosphorus particles was adjusted to 0.925 g and 0.075 g, respectively.

[0151] Example 4

[0152] The procedure was carried out in the same manner as Example 1, but with the difference that the mixing amounts of LPSCl and finely pulverized red phosphorus particles were adjusted to 0.9 g and 0.1 g, respectively.

[0153] Example 5

[0154] The procedure was carried out in the same manner as Example 1, except that the amount of mixture of LPSCl and finely pulverized red phosphorus particles was adjusted to 0.8 g and 0.2 g, respectively.

[0155] Example 6

[0156] 0.27g of LPSCl was filled into a mold and a first solid electrolyte layer was formed by applying primary pressure at a molding pressure of approximately 145 MPa.

[0157] Next, 0.03g of the solid electrolyte of Example 5 was filled onto the top of the first solid electrolyte layer and first pressurized at a molding pressure of about 145 MPa, and then secondarily pressurized at a pressure of 380 MPa to form a second solid electrolyte layer. Through these steps, a double-layer solid electrolyte membrane having a structure in which the first solid electrolyte layer and the second solid electrolyte layer are sequentially stacked was manufactured.

[0158] Comparative Example 1

[0159] 0.3g of LPSCl was filled into a mold, and a solid electrolyte membrane in the form of a pellet was formed by first applying a fabrication pressure of about 145 MPa and second applying a fabrication pressure of about 380 MPa.

[0160] Comparative Example 2

[0161] A double-layer solid electrolyte membrane was prepared by carrying out the same procedure as in Example 6, but with the only difference being that 0.03g of LPSCl was filled into the top of the first solid electrolyte layer and molding pressure was applied.

[0162] Preparation Example: Preparation of a solid-state battery

[0163] Manufacturing of symmetric cells

[0164] A symmetrical all-solid-state cell was manufactured by arranging a lithium metal layer (about 100 μm thick) - a solid electrolyte membrane - a lithium metal layer in that order, and then pressurizing it to a pressure of about 35 MPa. At this time, the solid electrolyte membranes of Examples 1 to 6 and Comparative Examples 1 and 2 were used as the solid electrolyte membranes (Preparation Examples 1 to 6, Comparative Preparation Examples 1 and 2).

[0165] Preparation of full-cell cells

[0166] Cathode active material LiNi 0.8 Co 0.1 Mn 0.1A cathode composite was prepared by mixing 0.12 g of O2 (NCM811), 0.01 g of VGCF (Vapor grown carbon fiber) as a conductive material, and 0.07 g of LPSCl. 0.3 g of the solid electrolyte of Example 3 was filled into a mold, and a solid electrolyte membrane was formed by applying a first pressurization pressure of approximately 145 MPa. 0.0056 g of the cathode composite was filled into the top of the solid electrolyte membrane, and a cathode layer was formed by applying a first pressurization pressure of approximately 145 MPa and a second pressurization pressure of approximately 380 MPa. A lithium metal layer (approx. 100 μm thick) was placed on the bottom of the solid electrolyte membrane (the side opposite the cathode layer), and an all-solid-state battery was manufactured by applying pressure and fixing with a stacking pressure of approximately 35 MPa (Preparation Example 7).

[0167] The battery compositions of Manufacturing Examples 1 to 7 and Comparative Manufacturing Examples 1 to 2 are shown in Table 1 below.

[0168] Classification Solid Electrolyte Membrane Form Remarks Preparation Example 1 Example 1 Symmetric Cell LPSCl + Red Phosphorus (2.5 wt%) Preparation Example 2 Example 2 Symmetric Cell LPSCl + Red Phosphorus (5.0 wt%) Preparation Example 3 Example 3 Symmetric Cell LPSCl + Red Phosphorus (7.5 wt%) Preparation Example 4 Example 4 Symmetric Cell LPSCl + Red Phosphorus (10.0 wt%) Preparation Example 5 Example 5 Symmetric Cell LPSCl + Red Phosphorus (20.0 wt%) Preparation Example 6 Example 6 Symmetric Cell 1st Solid Electrolyte Layer (90 wt%): LPSCl 2nd Solid Electrolyte Layer (10 wt%): LPSCl + Red Phosphorus (20.0 wt%) Preparation Example 7 Example 3 Full-cell Cathode: NCM811 Solid Electrolyte Membrane: LPSCl + Red Phosphorus (7.5 wt%) Cathode: Lithium metal layer Comparative Preparation Example 1 Comparative Example 1 Symmetric cell LPSCl Comparative Preparation Example 2 Comparative Example 2 Symmetric cell 1st solid electrolyte layer (90 wt%): LPSCl 2nd solid electrolyte layer (10 wt%): LPSCl

[0169] <Experimental Example>

[0170] Experimental Example 1: Confirmation of the Microstructure of a Solid Electrolyte Membrane

[0171] The top and cross-section of the solid electrolyte membrane of Example 4 (red phosphorus content 10 wt%) were photographed using a scanning electron microscope (SEM) to capture the microstructure, and observed using energy dispersive X-ray spectroscopy (EDS), with each image shown in Figures 3a and 3b.

[0172] Referring to Figures 3a and 3b, it can be seen that red phosphorus particles (= phosphorus (P) element) are uniformly dispersed in the form of particles within the solid electrolyte membrane.

[0173] Experimental Example 2: Confirmation of Crystal Structure and Raman Shift of Solid Electrolyte Membrane

[0174] X-ray diffraction (XRD) and Raman spectroscopy analysis were performed on the solid electrolyte membrane of Example 4 (red phosphorus content 10 wt%), and the results are shown in Figures 4a and 4b. The XRD and Raman spectroscopy results of LPSCl and red phosphorus (Red P) are shown together as a comparison group.

[0175] Referring to Figures 4a and 4b, it can be confirmed that the X-ray diffraction (XRD) and Raman spectroscopy of the solid electrolyte membrane of Example 3 include peaks observed in LPSCl and red phosphorus (Red P), and that the peak intensity remains the same. This confirms that LPSCl and red phosphorus (Red P) are stably mixed without chemical side reactions.

[0176] Experimental Example 3: Electrochemical Impedance Spectroscopic Analysis of Solid Electrolyte Membrane

[0177] Electrochemical Impedance Spectroscopy (EIS) was performed on the solid electrolyte membranes of Example 4 (red phosphorus content 10 wt%) and Comparative Example 1 to measure ionic conductivity, and the results are shown in Fig. 5. A symmetric cell consisting of SUS foil | solid electrolyte membrane | SUS foil was used, and EIS analysis was performed by applying an amplitude of 10 mV in a frequency range from 1 MHz to 10 mHz at room temperature.

[0178] Referring to Fig. 5, it can be confirmed that the solid electrolyte membrane of Example 4 (approx. 1.111 mS / cm) has a slightly lower ionic conductivity compared to the solid electrolyte membrane of Comparative Example 1 (approx. 1.929 mS / cm) made of pure LPSCl, but still has a high ionic conductivity of 1 mS / cm or more, so it can be suitably utilized as a solid electrolyte.

[0179] Experimental Example 4: Constant Current Experiment

[0180] A constant current of 1 mA / cm² (cutoff voltage: 0.02 V or less or 5 V or more) was applied to the all-solid-state batteries (symmetric cells) of Preparation Examples 1 to 5 and Comparative Preparation Example 1, and the critical electrodeposition capacity was measured, and the results are shown in FIGS. 6a and 6b. In the present invention, the critical electrodeposition capacity is defined as the limit capacity at the point where cell failure (cell degradation) occurs, and this was measured as the electrodeposition capacity at the point where the voltage of the battery becomes 20 mV or less due to an internal short circuit, or where the voltage of the battery becomes 5 V due to a large overvoltage.

[0181] Referring to FIGS. 6a and 6b, it can be seen that the solid electrolyte membranes of Preparation Examples 1 and 2 and Comparative Preparation Example 1, in which the content of red phosphorus particles contained in the solid electrolyte membrane is less than 6 parts by weight, exhibit only partial capacity (=low critical electrodeposition capacity) and an internal short circuit occurs. On the other hand, it can be seen that Preparation Examples 3 to 5, in which the content of red phosphorus particles is 6 parts by weight or more, exhibit sufficient capacity without an internal short circuit.

[0182] Meanwhile, although the cases of Preparation Examples 4 and 5 (red phosphorus content 10 wt% and 20 wt%, respectively) did not exhibit a low critical electrodeposition capacity, it was found that as the red phosphorus content became excessive, the ionic conductivity of the solid electrolyte membrane decreased and the overpotential increased during the electrodeposition process, resulting in a decrease in the critical electrodeposition capacity.

[0183] The critical electrodeposition capacities of Preparation Examples 1 to 5 and Comparative Preparation Example 1 are shown in Table 2 below.

[0184] Critical Electrodeposition Capacity (mAh / cm²) Preparation Example 11.50 Preparation Example 21.65 Preparation Example 319.04 Preparation Example 413.40 Preparation Example 512.10 Comparative Preparation Example 11.57

[0185] Experimental Example 5: Measurement of Critical Current Density

[0186] For the all-solid-state batteries (symmetric cells) of Preparation Example 3 (red phosphorus content 7.5 wt%) and Comparative Preparation Example 1, electrodeposition and desorption were started under current and capacity conditions of 0.5 mA / cm² and 0.5 mAh / cm², respectively, and then the critical current density at which an internal short circuit occurs was measured while increasing the constant current value by 0.5 mA / cm² for each cycle, and the results are shown in Fig. 7a (Comparative Preparation Example 1) and Fig. 7b (Preparation Example 3), respectively.

[0187] Referring to Figures 7a and 7b, the critical current density of the battery in Comparative Example 1 was measured to be low at approximately 2.0 mA / cm², whereas it was confirmed that the battery in Example 3 operated stably even when the constant current value was increased up to 100.0 mA / cm². These results suggest that a solid electrolyte membrane containing red phosphorus particles can effectively suppress internal short circuits in the battery under high current density conditions.

[0188] Experimental Example 6: Evaluation of Cycle Performance

[0189] The cycle performance of the all-solid-state battery (symmetric cell) of Preparation Example 3 was evaluated under high current density conditions of 5, 10, and 20 mA / cm². The experiment was conducted with the capacity per unit area fixed at 1 mAh / cm² during the electrodeposition and delamination processes, and the results are shown in FIGS. 8a to 8c.

[0190] Referring to FIGS. 8a to 8c, it was confirmed that the battery of Example 4 operated stably for more than 3,300, 850, and 550 cycles, respectively, under current density conditions of 5, 10, and 20 mA / cm².

[0191] Experimental Example 7: X-ray Photoelectron Spectroscopy Analysis

[0192] For the all-solid-state batteries (Pristine) of Preparation Example 6 and Comparative Preparation Example 2, a deposition process was performed for 10 hours with a constant current of 1 mA / cm², after which the batteries were disassembled and X-ray Photoelectron Spectroscopy (XPS) analysis was performed on the interface between the first solid electrolyte layer and the second solid electrolyte layer (SE / SE interface) and the interface between the lithium metal layer and the second electrolyte layer (Li / SE interface) (see schematic diagram of Fig. 9), and the results are shown in Figs. 10a, 10b, 11a, and 11b.

[0193] In the case of Comparative Example 2 (Fig. 10a), the peak intensity for the decomposition product (Reduced P) of LPSCl at the SE / SE interface increased after electrodeposition, indicating that lithium dendrites grew to the bottom of the first solid electrolyte layer and decomposed LPSCl. On the other hand, in Example 6 (Fig. 10b), which includes a second solid electrolyte layer in which red phosphorus particles are dispersed in a solid electrolyte membrane, LPSCl building block (PS4) at the SE / SE interface even after electrodeposition 3- Judging by the fact that the peak intensity of ) was maintained, it was confirmed that the lithium dendrites did not reach the SE / SE interface.

[0194] In addition, referring to FIGS. 11a and 11b, it can be confirmed that compared to Comparative Example 2 (Fig. 11a), the intensity of the peaks corresponding to the decomposition products of LPSCl and red phosphorus at the Li / SE interface increased in Example 6 (Fig. 11b) after electrodeposition. Therefore, it was confirmed that using a solid electrolyte membrane containing red phosphorus particles inhibits the growth of lithium dendrites in the vertical direction and limits them to the vicinity of the Li / SE interface.

[0195] Experimental Example 8: Evaluation of Rate Characteristics

[0196] The rate characteristics of the all-solid-state battery (complete battery) of Preparation Example 7 were evaluated in the range of 0.2C to 10C, and the results are shown in FIG. 12. Referring to FIG. 12, it was confirmed that the battery of Preparation Example 7 operated normally without an internal short circuit even under the condition of 10C.

[0197] In addition, the cycle performance of the battery of Preparation Example 7 was evaluated under high rate conditions of 5C, and the results are shown in FIG. 13. Referring to FIG. 13, it was confirmed that the all-solid-state battery of Preparation Example 7 exhibited excellent high-rate cycle characteristics, maintaining a capacity retention rate of approximately 70.75% up to 350 cycles even under high rate conditions of 5C.

[0198] Although preferred embodiments have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concepts defined in the following claims are also included within the scope of the present invention.

[0199] [National R&D projects that supported this invention]

[0200] [Project ID] 2410004164

[0201] [Assignment No.] 20024818

[0202] [Ministry Name] Ministry of Trade, Industry and Energy

[0203] [Name of Project Management (Specialized) Agency] Korea Institute of Industrial Technology Planning and Evaluation

[0204] [Research Project Name] Development of Materials and Components Technology

[0205] [Project Title] Development of High-Strength, Corrosion-Resistant, Lightweight Current Collector Material Technology for Sulfide-Based All-Solid State Batteries

[0206] [Name of Project Performing Organization] Premtu Co., Ltd.

[0207] [Research Period] 2023.07.01 ~ 2026.12.31

[0208] [National R&D projects that supported this invention]

[0209] [Project ID] 2710006309

[0210] [Assignment No.] 00408823

[0211] [Ministry Name] Ministry of Science and ICT

[0212] [Name of Project Management (Specialized) Agency] National Research Foundation of Korea

[0213] [Research Project Name] Nano and Materials Technology Development Project

[0214] [Project Title] Development of Single-Crystal Anode Synthesis Technology for Waste Battery Recycling Based on Sliding Door-Type Cell Disassembly Technology and Interparticle Lithium Composition Equilibrium Technology

[0215] [Name of Project Performing Organization] Seoul National University Industry-Academic Cooperation Foundation

[0216] [Research Period] 2024.04.01 ~ 2028.12.31

[0217] [National R&D projects that supported this invention]

[0218] [Project ID] 2710006479

[0219] [Assignment No.] 00429941

[0220] [Ministry Name] Ministry of Science and ICT

[0221] [Name of Project Management (Specialized) Agency] National Research Foundation of Korea

[0222] [Research Project Name] International Cooperation Development Project for Original Technology

[0223] [Project Title] Development of High-Entropy Electrolytes for Hybrid Aqueous Zinc Secondary Batteries via Artificial Intelligence Machine Learning

[0224] [Name of Project Performing Organization] Seoul National University Industry-Academic Cooperation Foundation

[0225] [Research Period] May 1, 2024 ~ December 31, 2028

Claims

1. Sulfide-based solid electrolyte; and A solid electrolyte membrane comprising red phosphorus particles dispersed in the above-mentioned sulfide-based solid electrolyte.

2. In Paragraph 1, The above sulfide-based solid electrolyte is a solid electrolyte membrane comprising an azirodite-type sulfide represented by the following chemical formula 1. [Chemical Formula 1] In the above chemical formula 1, 4≤a≤8 and, M 1 is Mg, Cu, Ag, or a combination thereof, 0≤b<0.5, and M 2 is Na, K, or a combination thereof, 0≤c<0.5, and M 3 is Sn, Zn, Si, Sb, Ge, or a combination thereof, and 0 <d<4, 0≤e<1 이고, M 4 is O, SO n , or a combination thereof, 1.5≤n≤5, 3≤f≤12, 0≤g<2, and X is F, Cl, Br, I, or a combination thereof, and 0≤h≤2.

3. In Paragraph 1, A solid electrolyte membrane comprising the above red phosphorus particles in an amount of 2 to 20 parts by weight per 100 parts by weight of the above sulfide-based solid electrolyte.

4. In Paragraph 4, A solid electrolyte membrane comprising the above red phosphorus particles in an amount of 7 to 9 parts by weight per 100 parts by weight of the above sulfide-based solid electrolyte.

5. In Paragraph 1, The above red phosphorus particles are a solid electrolyte membrane having an average particle size of 10 nm to 10 μm.

6. In Paragraph 1, The above solid electrolyte membrane comprises a first solid electrolyte layer including the sulfide-based solid electrolyte; and A solid electrolyte membrane comprising: a second solid electrolyte layer formed on the first solid electrolyte layer and comprising the sulfide-based solid electrolyte and red phosphorus particles dispersed within the sulfide-based solid electrolyte.

7. In Paragraph 1, The first solid electrolyte layer above includes red phosphorus particles, and A solid electrolyte membrane in which the red phosphorus particle content of the first solid electrolyte layer is less than the red phosphorus particle content of the second solid electrolyte layer.

8. In Paragraph 7, A solid electrolyte membrane in which the ratio of red phosphorus particle content between the first solid electrolyte layer and the second solid electrolyte layer is 1:3 to 1:

10.

9. In Paragraph 7, The red phosphorus particles of the second solid electrolyte layer above are a solid electrolyte membrane having a concentration gradient.

10. In Paragraph 6, A solid electrolyte film having a thickness ratio of 5:1 to 15:1 for the first solid electrolyte layer and the second solid electrolyte layer.

11. (S1) A step of pulverizing red phosphorus particles; and (S2) A step of mixing and press-molding the sulfide-based solid electrolyte and the finely pulverized red phosphorus particles; comprising Method for manufacturing a solid electrolyte membrane.

12. In Paragraph 11, (S3) A step of press-molding a sulfide-based solid electrolyte; and (S4) A step of placing a solid electrolyte membrane formed in step (S2) on top of a sulfide-based solid electrolyte formed in step (S3) and pressurizing it; further comprising Method for manufacturing a solid electrolyte membrane.

13. An all-solid-state battery comprising: an anode; a cathode; and a solid electrolyte membrane interposed between the anode and the cathode, comprising a solid electrolyte membrane according to claim 1.

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