KR20190142119A - A solid electrolyte layer and an all-solid-state battery comprising the same - Google Patents

Abstract

The present invention relates to a solid electrolyte membrane for an all-solid-state battery and a battery comprising the same. In the present invention, the battery may include lithium metal as a negative electrode active material. According to the present invention, the solid electrolyte membrane for an all-solid-state battery has an effect of inhibiting lithium dendrite growth by ionizing lithium precipitated as a metal. Therefore, in the case of using lithium metal as a negative electrode in the all-solid-state battery including the solid electrolyte membrane, the lithium dendrite growth is delayed and/or inhibited and electrical shorts due to dendrite growth are effectively prevented.

Description

A solid electrolyte layer and an all-solid-state battery comprising the same

The present invention relates to a solid electrolyte membrane for an all-solid-state battery and a battery including the same. The present invention also relates to an all-solid-state battery containing lithium metal as a negative electrode active material.

Lithium ion batteries using a liquid electrolyte have a structure in which a negative electrode and a positive electrode are partitioned by a separator, and thus, when the separator is damaged by deformation or external shock, a short circuit may occur, which may lead to a risk of overheating or explosion. Therefore, the development of a solid electrolyte capable of securing safety in the field of lithium ion secondary batteries is a very important task.

A lithium secondary battery using a solid electrolyte has an advantage of increasing battery safety, preventing leakage of an electrolyte solution, improving battery reliability, and facilitating manufacture of a thin battery. In addition, lithium metal may be used as a negative electrode, thereby improving energy density. Accordingly, application of a lithium secondary battery to a high capacity secondary battery for an electric vehicle is expected as a next-generation battery.

As the solid electrolyte, a polymer material of an ion conductive material may be used, or an inorganic material of an oxide or a sulfide having ion conducting properties may be used. A hybrid material in which a polymer material and an inorganic material are mixed is also proposed.

On the other hand, when lithium metal is used as the negative electrode active material, there is a problem that lithium dendrites grow from the surface of the negative electrode, and when the grown lithium dendrites come into contact with the positive electrode, a short circuit of the battery is caused. 1 is a diagram showing such a conventional all-solid-state battery. In an all-solid-state battery, a solid electrolyte membrane instead of a separator serves as a positive and negative electrical insulator. However, when a polymer material is used as the solid electrolyte, the solid electrolyte membrane may be damaged due to the growth of lithium dendrites. 1 is a schematic diagram illustrating a short circuit generation mechanism according to lithium dendrite growth in an all-solid-state battery using a solid electrolyte. In addition, the inorganic solid electrolyte is generally formed in a layered structure by integrating a particulate ion conductive inorganic material, and contains a large number of pores by interstitial volume between the particles. Accordingly, lithium dendrites may grow into the space provided by the pores, and when the lithium dendrites grown through the pores come into contact with the positive electrode, a short circuit may occur. Accordingly, development of an electrolyte membrane for an all-solid-state battery capable of suppressing lithium dendrite growth is required.

The present invention has been made to solve the above problems, and an object thereof is to provide a solid electrolyte membrane for an all-solid-state battery in which lithium dendrite growth is suppressed. In addition, another object of the present invention is to provide an all-solid-state battery containing lithium metal as a negative electrode active material. Other objects and advantages of the invention will be understood by the following description. On the other hand, it will be readily apparent that the objects and advantages of the present invention may be realized by the means or method described in the claims, and combinations thereof.

The present invention has been proposed to solve the above technical problem and relates to a solid electrolyte membrane for an all-solid-state battery. A first aspect of the present invention relates to the solid electrolyte membrane, wherein the solid electrolyte membrane has an ionic conductivity of 1 × 10 ⁻⁵ S / cm or more, and the solid electrolyte membrane includes a suppression layer including a dendrite growth inhibitory substance (a). Including the above, the dendrite growth inhibitory material (a) is derived from any one of (a1) metal (s) having a lower ionization tendency than lithium and (a2) at least two alloy (s) of the metals, It is contained in the said suppression layer in the form of at least any one of these salts and these ions.

According to a second aspect of the present invention, in the first aspect, the metal is K, Sr, Ca, Na, Mg, Be, Al, Mn, Zn, Cr (+3), Fe, Cd, Co, Ni, Sn It includes one or more selected from the group consisting of, Pb, Cu, Hg, Ag, Pd, Ir, Pt (+2), Au and Pt (+4).

In a third aspect of the invention, in any one of the foregoing aspects, the inhibitory substance comprises at least one member selected from the group consisting of Au and Pt.

According to a fourth aspect of the present invention, in any one of the above-described aspects, the metal salt is chloride, iodide, cyanide, bromide, sulfide, hydrate It is one or more of hydroxide, phosphite and chloride hydrate.

In a fifth aspect of the present invention, in any one of the aforementioned aspects, the solid electrolyte membrane comprises at least two solid electrolyte layers and at least one inhibitory layer, wherein the inhibitory layer is disposed between the solid electrolyte layers.

In a sixth aspect of the present invention, in any one of the above-described aspects, the solid electrolyte membrane is formed by sequentially stacking a first solid electrolyte layer, a suppression layer, and a second solid electrolyte layer.

In a seventh aspect of the invention, in any one of the preceding aspects, the solid electrolyte membrane comprises an ion conductive solid electrolyte material, wherein the ion conductive solid electrolyte material comprises a polymer solid electrolyte, an inorganic solid electrolyte, or both. It includes a mixture.

In an eighth aspect of the invention, in any one of the aforementioned aspects, the polymer solid electrolyte comprises a polymer resin and a solvated lithium salt.

A ninth aspect of the present invention relates to an electrochemical device, wherein the electrochemical device is an all-solid-state battery including a negative electrode, a positive electrode, and a solid electrolyte membrane interposed between the negative electrode and the positive electrode, and the negative electrode includes lithium metal. The solid electrolyte membrane is in accordance with any one of the aforementioned aspects.

The solid electrolyte membrane for an all-solid-state battery according to the present invention has an effect of inhibiting lithium dendrite growth by ionizing lithium precipitated as a metal. Therefore, in the case of using lithium metal as a negative electrode in the all-solid-state battery including the solid electrolyte membrane, lithium dendrite growth is delayed and / or suppressed, and thus an electrical short circuit due to the dendrite growth can be effectively prevented.

BRIEF DESCRIPTION OF THE DRAWINGS The drawings appended hereto illustrate preferred embodiments of the present invention, and together with the teachings of the present invention serve to better understand the technical idea of the present invention, the present invention is limited only to those described in such drawings. It is not to be interpreted. On the other hand, the shape, size, scale or ratio of the elements in the drawings included in this specification may be exaggerated to emphasize a more clear description.
1 is a diagram illustrating a problem in which lithium dendrites grow from a negative electrode and cause a short circuit in a conventional all-solid-state battery.
2 schematically illustrates a solid electrolyte membrane according to an embodiment of the present invention.
FIG. 3 schematically illustrates an all-solid-state battery according to an embodiment of the present invention, which schematically illustrates a reaction in which lithium dendrite growth is inhibited by a growth inhibitory material included in the all-solid electrolyte membrane.
4 schematically illustrates a solid electrolyte membrane including a patterned suppression layer.

Hereinafter, embodiments of the present invention will be described in detail. Prior to this, terms or words used in the specification and claims should not be construed as having a conventional or dictionary meaning, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the configurations described in the embodiments described herein are only one of the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention, and various equivalents may be substituted for them at the time of the present application. It should be understood that there may be variations.

Throughout this specification, when a part "contains" a certain component, it means that it can further include other components, without excluding the other components unless otherwise stated.

In addition, the terms "about", "substantially", etc., as used throughout this specification, are used at the numerical values of or near the numerical values when manufacturing and material tolerances inherent to the meanings mentioned are provided to aid the understanding of the present application. In order to prevent the unfair use of unscrupulous infringers.

Throughout this specification, description of "A and / or B" means "A or B or both."

The specific terminology used in the detailed description that follows is for the purpose of convenience and not of limitation. The words 'right', 'left', 'up' and 'down' indicate directions in the figures to which reference is made. The words 'inwardly' and 'outwardly' indicate directions toward or away from the geometric center of the designated device, system and members thereof, respectively. 'Forward', 'backward', 'upward', 'downward' and related words and phrases indicate positions and orientations in the drawings to which reference is made and should not be limiting. These terms include the words listed above, their derivatives, and words of similar meaning.

The present invention relates to a secondary battery including the electrolyte membrane for the secondary battery and the electrolyte membrane. In the present invention, the secondary battery may be a lithium ion secondary battery. In one embodiment of the present invention, the secondary battery is an all-solid-state battery using a solid electrolyte as an electrolyte, and the battery may include lithium metal as a negative electrode active material.

2 schematically illustrates a secondary battery according to an embodiment of the present invention, and includes a solid electrolyte membrane between a positive electrode and a negative electrode. The configuration of the present invention will be described in more detail with reference to FIG. 2.

(1) solid electrolyte membrane

In the present invention, the solid electrolyte membrane includes two or more solid electrolyte layers. The solid electrolyte layer includes an ion conductive solid electrolyte material, and the solid electrolyte membrane may be applied as an ion conductive electrolyte to an all-solid-state battery that does not use a liquid electrolyte, for example. In addition, in the present invention, the solid electrolyte membrane includes at least one suppression layer, and the suppression layer is disposed between the at least two solid electrolyte layers. The inhibitory layer comprises a dendrite growth inhibitory material.

In the present invention, the solid electrolyte membrane includes an inhibitory layer and has an ionic conductivity of 1 × 10 ⁻⁵ S / cm or more, preferably 1 × 10 ⁻⁴ S / cm or more.

In one embodiment of the present invention, the solid electrolyte membrane may have a thickness in the range of 5㎛ to 500㎛. The solid electrolyte membrane may be, for example, 10 μm or more, 20 μm or more, 30 μm or more, 50 μm or more, 100 μm or more, 200 μm or more, or 300 μm or more, 400 μm or less, 300 μm or less, 200 μm or less, 100 μm The thickness may be 70 μm or less or 50 μm or less. For example, the thickness of the solid electrolyte membrane may be 30 μm to 50 μm.

The ion conductive solid electrolyte material may comprise one or more of a polymer solid electrolyte and an inorganic solid electrolyte.

In one embodiment of the present invention, the polymer solid electrolyte includes a polymer resin and a lithium salt, and is a solid polymer electrolyte having a mixture of a solvated lithium salt and a polymer resin, or an organic solvent and a lithium salt. It may be a polymer gel electrolyte in which the organic electrolyte solution is contained in the polymer resin.

In one embodiment of the present invention, the solid polymer electrolyte is, for example, a polymer resin, a polyether polymer, a polycarbonate polymer, an acrylate polymer, a polysiloxane polymer, a phosphazene polymer, a polyethylene derivative, alkylene One or two or more mixtures selected from the group consisting of oxide derivatives, phosphate ester polymers, poly agitation lysine, polyester sulfides, polyvinyl alcohol, polyvinylidene fluoride and ionic dissociation groups It may include, but is not limited thereto.

In a specific embodiment of the present invention, the solid polymer electrolyte is a polymer resin in which a copolymer of an amorphous polymer such as PMMA, polycarbonate, polysiloxane (pdms) and / or phosphazene is copolymerized in a polyethylene oxide (PEO) main chain It may include one or two or more kinds selected from the group consisting of branched copolymers, comb-like polymers and crosslinked polymer resins.

In addition, in one specific embodiment of the present invention, the polymer gel electrolyte includes an organic electrolyte solution containing a lithium salt and a polymer resin, and the organic electrolyte solution may include 60 to 400 parts by weight based on the weight of the polymer resin. The polymer resin applied to the gel electrolyte is not limited to a specific component, but for example, polyvinyl chloride (PVC), poly (methyl methacrylate), polyacrylonitrile (PAN), polyvinyl fluoride It may be one or a mixture of two or more selected from the group consisting of leadene (PVdF) and polyvinylidene fluoride-hexafluoropropylene (poly (vinylidene fluoride-hexafluoropropylene: PVdF-HFP)), but is not limited thereto.

In the electrolyte of the present invention, the lithium salt described above can be represented by Li ⁺ X ^- as an ionizable lithium salt. In this lithium salt anion (X) is not particularly ^{limited, F -, Cl -, Br} -, I -, NO 3 -, N (CN) 2 -, BF 4 -, ClO 4 -, PF 6 -, ( ^{_{CF 3) 2 PF 4 -,}} (CF 3) 3 PF 3 -, (CF 3) 4 PF 2 -, (CF 3) 5 PF -, (CF 3) 6 P -, CF 3 SO 3 -, CF 3 ^{_{CF 2 SO 3 -, (CF}} 3 SO 2) 2 N -, (FSO 2) 2 N -, CF 3 CF 2 (CF 3) 2 CO -, (CF 3 SO 2) 2 CH -, (SF 5) _{^{3 C -, (CF 3 SO}} 2) 3 C -, CF 3 (CF 2) 7 SO 3 -, CF 3 CO 2 -, CH 3 CO 2 -, SCN -, (CF 3 CF 2 SO 2) 2 N ^- and the like can be given.

Meanwhile, in one specific embodiment of the present invention, the polymer solid electrolyte may further include an additional polymer gel electrolyte. The polymer gel electrolyte has excellent ion conductivity (or 10 ⁻⁴ s / m or more), and has a binding property, thereby providing not only a function as an electrolyte, but also a binding force between the electrode active material and a binding force between the electrode layer and the current collector. The function of the electrode binder resin to provide can be provided.

Meanwhile, in the present invention, the solid electrolyte membrane may further include a crosslinking agent and / or an initiator when the solid electrolyte layer is prepared when a polymer material is used as the electrolyte material of the solid electrolyte layer. The crosslinking agent and / or the initiator is capable of initiating a crosslinking reaction or a polymerization reaction according to heat, light and / or temperature conditions, and the crosslinking agent and / or the initiator is not limited to any particular component as long as it can induce crosslinking and / or polymerization of the polymer material. In one embodiment of the present invention, an organic peroxide, an organometallic reagent such as silver alkylated, an azo compound, etc. may be used as the crosslinking agent and / or initiator, but is not limited thereto.

Meanwhile, in the present invention, the inorganic solid electrolyte may include a sulfide-based solid electrolyte, an oxide-based solid electrolyte, or both.

In a specific embodiment of the present invention, the sulfide-based solid electrolyte includes sulfur atoms in the electrolyte component, and is not particularly limited to specific components, such as crystalline solid electrolyte, amorphous solid electrolyte (glassy solid electrolyte), glass ceramic It may comprise one or more of the solid electrolytes. Specific examples of the sulfide-based solid electrolyte are LPS sulfides including sulfur and phosphorus, Li _{4 - x} Ge _{1 - x} P _x S ₄ (x is 0.1 to 2, specifically x is 3/4, 2/3) ), Li _{10 ± 1} MP ₂ X ₁₂ (M = Ge, Si, Sn, Al, X = S, Se), Li _3.833 Sn _0.833 As _0.166 S ₄ , Li ₄ SnS ₄ , Li _{3 . 25 Ge 0 .25 P 0. 75 S} 4, Li 2 SP 2 S 5, B 2 S 3 -Li 2 S, xLi 2 S- (100-x) P 2 S 5 (x 70 to 80), Li ₂ S-SiS ₂ -Li ₃ N, Li ₂ SP ₂ S ₅ -LiI, Li ₂ S-SiS ₂ -LiI, Li ₂ SB ₂ S ₃ -LiI and the like, but are not limited thereto.

In one specific embodiment of the present invention, the oxide-based solid electrolyte is, for example, LLT-based perovskite structure, such as Li _3x La _{2 / 3-x} TiO ₃ , such as Li ₁₄ Zn (GeO ₄ ) ₄ LISICON, LATP based Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ , LAGP based (Li _{1 + x} Ge _2-x Al _x (PO ₄ ) ₃ ), phosphate based LiPON, etc. It may be used, and is not particularly limited thereto.

(2) dendrite growth inhibitory substance

The solid electrolyte membrane according to the present invention includes a suppression layer, and the suppression layer includes a lithium dendrite growth inhibiting material. Dendrite growth inhibitory material may be abbreviated herein to be referred to as inhibitory material.

In the present invention, the inhibitory substance is lower in ionization tendency than lithium. The inhibitory material is less reactive than lithium, ie it has a low ionization tendency. For this reason, it is possible to prevent the lithium ions from being reduced to the lithium metal by the inhibitory substance, and also to reduce the amount of dendrites by oxidizing the precipitated lithium back to lithium ions.

In the present invention, the inhibitor (a) is a1) metal (s) having a lower ionization tendency than lithium; And a2) at least two alloy (s) of the metals having a lower ionization tendency than lithium; It is derived from at least one of these, and is a mixture containing at least any one of these salts and these ions, The said mixture is distributed in the suppression layer. That is, the suppression layer includes at least one of salts of the metal, salts of the alloy, ions of the metal and ions of the alloy.

In one embodiment of the present invention, the a1) metal is K, Sr, Ca, Na, Mg, Be, Al, Mn, Zn, Cr (+3), Fe, Cd, Co, Ni, Sn, Pb, It may be at least one selected from the group consisting of Cu, Hg, Ag, Pd, Ir, Pt (+2), Au and Pt (+4). In addition, the a2) alloy is alloyed two or more selected from the metal components. In one embodiment of the present invention, the metal salt is, for example, chloride, iodide, cyanide, boride, sulfide, hydroxide, phosphite ), One or more of chloride hydrate. However, as long as it can react with lithium metal to oxidize lithium metal in the form of ions, it is not limited, but is not limited to the above form. Meanwhile, in one embodiment of the present invention, the lower the ionization tendency, the higher the lithium dendrite growth inhibition effect. Accordingly, the inhibitor may include at least one of Au and Pt. In one embodiment of the present invention, when Au is used as the inhibitor, HAuCl ₄ .3H ₂ O in the form of a salt thereof may be added during preparation of the inhibitory layer, and when Pt is used as the inhibitor, H ₂ PtCl ₆ · H ₂ O in the form of a salt can be added during preparation of the inhibitory layer.

As described above, the electrolyte membrane according to the present invention includes an inhibitory material for inhibiting lithium growth, and thus, when applied to an all-solid-state battery including lithium metal as a negative electrode active material, it is possible to effectively suppress a short circuit due to lithium dendrite growth.

(3) Structure of the solid electrolyte membrane

In one embodiment of the present invention, the solid electrolyte membrane includes an inhibitory layer containing an inhibitory material, and may include two or more solid electrolyte layers and one or more inhibitory layers, and the inhibitory layer is disposed between the solid electrolyte layers. Is placed. For example, the solid electrolyte membrane may have a layered structure in which a first solid electrolyte layer, a suppression layer, and a second solid electrolyte layer are sequentially stacked. Alternatively, the solid electrolyte membrane may include first, second, and third solid electrolyte layers, wherein a first suppression layer is formed between the first and second solid electrolyte layers, and a second electrolyte layer is formed between the second and third solid electrolyte layers. 2 suppression layers may be disposed. Each of the inhibitory layers is independent of each other in terms of shape or material, and one of the inhibitory layers may be the same as or different from the other. In addition, each of the solid electrolyte layers is independent of each other in terms of shape or material, and one solid electrolyte layer may be the same as or different from the other.

In the present invention, the solid electrolyte membrane has an ion conductivity of 1x10 ^-5 S / cm or more, preferably 1x10 ^-4 S / cm or more in a state where the suppression layer is included.

The inhibitory layer is one in which the inhibitory substance is contained at a higher concentration than other layers (for example, the solid electrolyte layer). For example, the inhibitory layer may contain from 10% to 90% by weight of the inhibitory material relative to 100% by weight of the inhibitory layer. The content of inhibitory substance may be at least 30% by weight, at least 50% by weight, at least 70% by weight, at least 80% by weight, with or independently of which the content is at most 80% by weight, at most 70% by weight or 60%. It may be up to weight percent. The concentration of the inhibitor can be appropriately adjusted in consideration of the dendrite inhibitory effect, the ionic conductivity of the solid electrolyte membrane, and the manufacturing cost of the battery due to the use of the precious metal as the inhibitor. Meanwhile, in one embodiment of the present invention, at least 50% by weight of 100% by weight of the inhibitory material included in the solid electrolyte membrane may be included in the suppression layer.

In one embodiment of the present invention, the inhibitory layer may further comprise at least one of a binder resin and an ion conductive solid electrolyte material in addition to the inhibitory material. The binder resin may be used without particular limitation as long as it has a property of assisting bonding between the suppressing materials and bonding between the suppressing layer and another solid electrolyte layer and is an electrochemically stable component. Non-limiting examples of such binder resins are acrylic polymer, polyvinylidene fluoride polymer, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrroli DON, tetrafluoroethylene, ethylene-propylene-diene monomer (EPDM), sulfonated EPDM, styrene butadiene rubber, fluororubber, various copolymers, etc. are mentioned.

The inhibitory layer may have the inhibitory substance dispersed in an even distribution or non-uniform distribution throughout the restraint layer. Alternatively, the suppression layer may be patterned in such a way that the pattern units including the suppression material are regularly or irregularly arranged in the suppression layer, and the uncoated portion between the pattern units is a solid electrolyte layer stacked above and below the suppression layer. Can be landfilled. In one embodiment, the planar shape of the pattern elements can be linear or in the form of a closed curve of a circular or square shape. In the case of linear patterns, they may be formed such that they are parallel or intersecting with each other. The pattern units may further include an ion conductive solid electrolyte material, a binder resin, or both, as necessary. 4 is a diagram showing the shape of the suppression layer according to an embodiment of the present invention, which schematically illustrates an embodiment in which a plurality of linear pattern elements are included in the suppression layer.

High concentration in the above description means that the concentration of the inhibitory substance relative to 100% by weight of the pattern element is at least 50% by weight or at least 60% by weight or 70% by weight. On the other hand, between the pattern element of the suppression layer may be filled with the same material as the first solid electrolyte layer or the second solid electrolyte layer.

In one embodiment of the invention, the solid electrolyte layer preferably has an area of less than 80%, less than 70%, less than 60% or less than 50% of the area covered by the suppression layer relative to 100 area% of its surface. In the case where the suppression layer is formed in such a manner as to excessively cover the surface of the solid electrolyte layer, the ion conduction path may be blocked by the suppression layer, and thus the ion conductivity of the solid electrolyte membrane may be degraded. When the coating area of the suppression layer satisfies the above range, the lithium dendrite growth inhibitory effect is high, and a decrease in lithium ion conductivity due to formation of the suppression layer can be prevented. However, the shapes of the above-described suppression layer and the solid electrolyte membrane are exemplary and may be applied without particular limitation as long as the structural features of the present invention can be implemented.

In one specific embodiment of the present invention, the suppression layer may have a thickness greater than 0 and 100 μm, and may be 70 μm or less, or 50 μm or less or 30 μm or less within the above range.

In the present invention, the thickness of the suppression layer, the concentration of the suppression layer increase suppression material, the area where the suppression layer covers the solid electrolyte layer, and the like can be appropriately adjusted in consideration of the ionic conductivity of the solid electrolyte membrane. That is, the suppression layer included in the solid electrolyte membrane may have a thickness of the suppression layer, a concentration of the suppression material, and a suppression layer so that the solid electrolyte membrane may exhibit ionic conductivity of 1x10 ^-5 S / cm or more, preferably 1x10 ^-4 S / cm or more. The surface area of the solid electrolyte layer can be adjusted to have an appropriate range.

In one embodiment of the present invention, the inhibitory layer may be formed on the surface of the first solid electrolyte layer by applying and inhibiting a solution of the inhibitory substance mixed with a solvent. In this case, the inhibitory layer may be obtained in a state where a very thin thickness is coated on one surface of the first solid electrolyte layer. In this case, only the inhibitory material is included in the coated inhibitory layer so that the thickness of the inhibitory layer is very thin on a nanometer scale of less than 1 μm, preferably 100 nm or less, for example 80 nm or less, 70 nm or less or 60 nm or less. Can be. In other embodiments, if the inhibitory layer is formed in the form of a composite of the inhibitory material with a solid electrolyte material and / or binder resin, it may be thicker than the inhibitory layer formed solely of the inhibitory material.

In addition, the first and second solid electrolyte layers include an ion conductive solid electrolyte material and may further include an inhibitory material, a binder resin, or both, as necessary. The inhibitory material may be dispersed in a uniform distribution in the first and second solid electrolyte layers. In addition, the inhibitory material in 100% by weight of the solid electrolyte layer may be included in a ratio of 0% to 50% by weight. The content of the inhibitory substance in the solid electrolyte layer may be 40 wt% or less, 30 wt% or less, 20 wt% or 10 wt% or less within the above range.

For the inhibitory material and the ion conductive solid electrolyte material included in the suppression layer and the first and second solid electrolyte layers, reference may be made to the above.

Meanwhile, in one specific embodiment of the present invention, the composition of the ion conductive solid electrolyte included in the first and second solid electrolyte layers may be the same or different. For example, the first layer may comprise an oxide-based solid electrolyte material and the second layer may comprise a sulfide-based solid electrolyte material.

In one embodiment, the solid electrolyte membrane may be made in such a manner that after forming the first solid electrolyte layer, a suppression layer is formed on the surface thereof and a second solid electrolyte layer is formed on the surface of the suppression layer. If two or more suppression layers are included, a method of forming a suppression layer on the surface of the second solid electrolyte layer and then forming a third solid electrolyte layer thereon may be prepared. In one embodiment of the present invention, in the case of producing a solid electrolyte membrane including at least one suppression layer or a solid electrolyte layer, the method of forming the suppression layer and the solid electrolyte layer may be repeated.

In one embodiment of the present invention, when the suppression layer is patterned, the suppression layer may be formed as a pattern layer having a convex pattern on the surface of the first solid electrolyte layer. Thereafter, the slurry for the second solid electrolyte layer may be coated on the surface of the suppression layer so that the uncoated portion (the suppression layer not formed portion) between the patterns may be filled with the second solid electrolyte. For example, suppression layer pattern elements including an inhibitory material are formed on the surface of the first solid electrolyte layer. The surface is then covered with a second solid electrolyte layer to form a solid electrolyte membrane. In one embodiment of the present invention, the second solid electrolyte layer may be formed from fluidized sludge. Thus, the slurry is applied to a surface of the first solid electrolyte layer on which the suppression layer pattern elements are formed, and the blank space between the pattern elements is embedded to space the space between the suppression layer / first solid electrolyte layer / second solid electrolyte layer. This can be prevented from forming.

Alternatively, the inhibitory layer may be formed in a manner of forming an recessed pattern having a predetermined thickness from the surface of the first solid electrolyte layer and then embedding an inhibitory material in the recessed pattern (inlay method). Thereafter, the surface of the suppression layer may be coated with a second solid electrolyte layer to obtain a solid electrolyte membrane.

(3) all-solid-state battery

The present invention provides an all-solid-state battery comprising the solid electrolyte membrane. In one embodiment of the present invention, the all-solid-state battery includes a negative electrode, a positive electrode, and a solid electrolyte membrane interposed between the negative electrode and the positive electrode, wherein the solid electrolyte membrane has the characteristics described above.

On the other hand, in one embodiment of the present invention, the all-solid-state battery is disposed so that the first solid electrolyte layer of the electrolyte membrane comprises a lower concentration of the inhibitory material than the suppression layer, the first solid electrolyte layer facing the negative electrode Can be. In the all-solid-state battery having such a structure, the first solid electrolyte layer has a higher concentration of inhibitory material than the second solid electrolyte layer, or a thicker thickness of the first solid electrolyte layer than the thickness of the second solid electrolyte layer. Both features can be provided.

In addition, in one embodiment of the present invention, an element such as a separate protective layer may be further added to the surface of the solid electrolyte membrane facing the cathode. In particular, a passivation film using an inorganic solid electrolyte, an inorganic material such as LiF, Li ₂ O, or an organic material such as PEO may be disposed in order to suppress a reaction by direct contact with Li metal.

In the present invention, the negative electrode may include a current collector, a negative electrode active material layer formed on the surface of the current collector, the negative electrode active material layer includes at least one element belonging to alkali metal, alkaline earth metal, group 3B and transition metal. can do. In a specific embodiment of the present invention, a non-limiting example of the alkali metal group consisting of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs) or francium (Fr) At least one metal selected from and preferably comprises lithium. In one specific embodiment of the present invention, the negative electrode may be a negative electrode current collector and a lithium metal thin film having a predetermined thickness by binding and laminated.

In the present invention, the positive electrode includes a current collector and a positive electrode active material layer formed on at least one side of the current collector, and the upper electrode active material layer includes a positive electrode active material, a solid electrolyte, and a conductive material. In addition, in one specific embodiment of the present invention, the positive electrode active material layer may further include a binder material. The binder material may increase the binding force between the positive electrode active material layer and the current collector and / or the solid electrolyte membrane, and may also help improve the binding force between components included in the positive electrode active material independently or in addition thereto.

The positive electrode active material can be used without limitation as long as it can be used as a positive electrode active material of a lithium ion secondary battery. For example, the positive electrode active material may be a layered compound such as lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), or a compound substituted with one or more transition metals; Lithium manganese oxides such as Li _{1 + x} Mn _{2 - x} O ₄ (where x is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ , LiMnO _2, and the like; Vanadium oxides such as lithium copper oxide (Li ₂ CuO ₂ ); LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ , and Cu ₂ V ₂ O ₇ ; Represented by the formula LiNi _{1 - x} M _x O ₂ , wherein M = Co, Mn, Al, Cu, Fe, Mg, B, or Ga, including one or more of the above elements, wherein x = 0.01 to 0.3 Lithium nickel oxide, for example LiN _{0 . 8 C 0 .1 M 0. 1 O} 2; Formula _{LiMn 2-x M x O 2} ( where, M = Co, Ni, Fe , Cr, and Zn, or Ta, x = 0.01 ~ 0.1 Im) or Li ₂ Mn Lithium manganese composite oxide represented by ₃ MO ₈ , wherein M = Fe, Co, Ni, Cu, or Zn; Spinel-structure lithium manganese composite oxides represented by LiNi _x Mn _{2 - x} O ₄ ; LiMn ₂ O _{4 in} which Li is partially substituted with alkaline earth metal ions; disulfide compounds; Fe ₂ (MoO ₄ ) ₃ and the like. However, it is not limited only to these.

The conductive material is not particularly limited as long as it has conductivity without causing chemical change in the battery. Examples of the conductive material include graphite such as natural graphite and artificial graphite; Carbon blacks such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fibers and metal fibers such as VGCF (Vapor grown carbon fibers); Metal powders such as carbon fluoride powder, aluminum powder and nickel powder; Conductive whiskeys such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; It may include one or a mixture of two or more selected from conductive materials such as polyphenylene derivatives.

The binder material is not particularly limited as long as it is a component that assists the bonding between the active material and the conductive material and the bonding to the current collector. For example, polyvinylidene fluoride polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxide Roxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer (EPDM), sulfonated EPDM, styrene butadiene rubber, fluorine rubber, various airborne Coalescence, etc. are mentioned. The binder resin may typically be included in the range of 1 to 30% by weight, or 1 to 10% by weight relative to 100% by weight of the electrode layer.

In one embodiment of the present invention, the negative electrode and / or the positive electrode may further include various additives for the purpose of supplementing or improving the physicochemical properties. The additive is not particularly limited, but may include one or more additives such as an oxidation stabilizer, a reduction stabilizer, a flame retardant, a heat stabilizer, an antifogging agent, and the like.

In addition, the current collector is generally made to a thickness of 3 to 500 ㎛. Such a current collector is not particularly limited as long as it has high conductivity without causing chemical change in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel Surface-treated with carbon, nickel, titanium, silver, and the like on the surface may be used. Among them, it may be appropriately selected according to the polarity of the positive electrode or the negative electrode.

The present invention also provides a battery module including the secondary battery as a unit cell, a battery pack including the battery module, and a device including the battery pack as a power source.

In this case, specific examples of the device may include a power tool moving by being driven by an electric motor; Electric vehicles including electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and the like; Electric motorcycles including electric bicycles (E-bikes) and electric scooters (E-scooters); Electric golf carts; Power storage systems and the like, but is not limited thereto.

(4) Manufacturing Method of Solid Electrolyte Membrane

Next, the manufacturing method of the solid electrolyte membrane which has the above-mentioned characteristic is demonstrated. The manufacturing method described below is one of various methods that can be employed in manufacturing the solid electrolyte membrane according to the present invention, but is not limited thereto. First, a first solid electrolyte layer is prepared. The electrolyte layer may be in accordance with the method for producing a solid electrolyte layer according to an embodiment of the present invention, it is not limited to a specific method. For example, when the electrolyte layer is a polymer electrolyte, the solid electrolyte layer may be prepared by the following method. A polymer solution is prepared by dissolving a polymer resin in an appropriate solvent such as acetonitrile, and lithium salt is added thereto to prepare a slurry for forming an electrolyte layer. The slurry may be warmed to an appropriate temperature for dissolving the polymer resin and the lithium salt, and may be stirred for several to several tens of hours. In addition, the polymer solution may further include an initiator and a curing agent. The initiator and the curing agent may be added together to the polymer solution or separately prepared an additive solution including the initiator and the curing agent to the slurry. In one specific embodiment of the present invention, the initiator may be included in the range of about 10 to 20 parts by weight based on the polymer resin used, the curing agent may be included in the range of about 0.2 to 3 parts by weight relative to the polymer resin used. The prepared slurry is then applied to a release film and dried. In this way a first solid electrolyte layer can be obtained. The release film may be removed in the final step after removing the release film and using the first solid electrolyte layer or otherwise forming a solid electrolyte membrane having all the elements.

Next, a suppression layer is formed on the surface of the first solid electrolyte layer. The inhibitory layer may be prepared in the form of a metal salt solution. For example, prepared by dissolving a hydrated metal salt in ethanol or the like, it is applied to the surface of the solid electrolyte layer and dried to be coated on the surface of the solid electrolyte layer to be prepared in an integrated state. The coating may be in accordance with conventional coating methods such as spin coating, dip coating, and the like, but is not limited to a specific method.

Thereafter, a second solid electrolyte layer is formed on the surface of the suppression layer. The second solid electrolyte layer is prepared in the form of a second solid electrolyte layer forming slurry like the first solid electrolyte layer, and then coated on the surface of the suppression layer and dried to form an integrated form with the suppression layer or the first solid electrolyte layer. After forming the coating on the surface of a separate release film, the release film can be removed and bonded to the surface of the suppression layer by calendering or lamination.

Meanwhile, in one specific embodiment of the present invention, the second solid electrolyte layer is further formed on the surface of the suppression layer, and the third solid electrolyte layer is disposed on the surface of the suppression layer to include two or more suppression layers. It is possible to provide a solid electrolyte membrane in the form.

Although the above manufacturing method has been described that each solid electrolyte layer includes a polymer solid electrolyte, the present invention is not limited thereto, and each solid electrolyte layer may include an inorganic solid electrolyte in place of or with a polymer solid electrolyte as an electrolyte material. Can be.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the following Examples are provided to illustrate the present invention, and the scope of the present invention is not limited thereto.

Example 1

1. Preparation of solid electrolyte membrane

(1) Preparation of the first solid electrolyte layer

4 wt% of a polymer solution was prepared by melting polyethylene oxide (Acetonitrile, AN) in polyethylene oxide (PEO, Mw = 4,000,000 g / mol). At this time, LiTFSI was put together with a lithium salt such that [EO] / [Li +] = 18/1 (molar ratio). The polymer solution was stirred overnight at 70 ° C. to sufficiently dissolve PEO and lithium salts. Next, an additive solution containing an initiator and a curing agent was prepared. The curing agent is PEGDA (Mw = 575), the initiator is benzoyl peroxide (BPO), polyethylene glycol diacrylate (PEDADA) is 20 wt% compared to PEO, BPO amount of PEGDA 1% Acetonitrile was used as the solvent. The additive solution was stirred for about 1 hour so that the added ingredients were mixed well. The additive solution was then added to the polymer solution and the two solutions were mixed sufficiently. The mixed solution was applied and coated onto a release film using a doctor blade. The coating gap was 800 µm and the coating speed was 20 mm / min. The solution-coated release film was moved to a glass plate to keep the horizontal well, dried overnight at room temperature, and vacuum dried at 100 ° C. for 12 hours. In this way, a first solid electrolyte layer was obtained. The thickness of the obtained first solid electrolyte layer was about 50 μm.

(2) Inhibition layer manufacture

A metal salt solution was prepared by dissolving HAuCl ₄ 3H ₂ O in ethanol at a concentration of 2 wt%. 20 μl of the metal salt solution was coated on the first solid electrolyte layer obtained in the previous step by spin coating at a speed of 2,000 rpm.

(3) Preparation of Second Solid Electrolyte Layer

A second solid electrolyte layer was prepared in the same manner as the preparation of the first solid electrolyte layer.

(4) Preparation of a multilayer structure solid electrolyte membrane

The first solid electrolyte membrane and the second solid electrolyte membrane coated with the suppression layer were stacked and stacked and calendered at 60 ° C. by adjusting the gap between the rolls to 100 μm. At this time, the suppression layer was disposed between the first and second solid electrolyte membranes. In this manner, a solid electrolyte membrane obtained by sequentially stacking a first solid electrolyte membrane, a suppression layer, and a second solid electrolyte membrane was obtained. The thickness of the obtained solid electrolyte membrane was about 100 μm. It was found that the suppression layer of the solid electrolyte membrane was formed so thin that it did not affect the total solid electrolyte membrane thickness.

2. Manufacturing of Anode

To the slurry produced electrode active material is _{NCM811 (LiNi 0. 8 Co 0} . 1 Mn 0. 1 O 2), conductive material

VGCF (Vapor grown carbon fiber) and a polymer-based solid solid electrolyte (PEO + LiTFSI, 18: 1 mol ratio) were mixed in a weight ratio of 80: 3: 17, added to acetonitrile and stirred to prepare an electrode slurry. An aluminum current collector having a thickness of 20 μm was prepared. The slurry was applied to the current collector using a doctor blade and the result was vacuum dried at 120 ° C. for 4 hours. The rolling process was carried out using a roll press to obtain an electrode loading of ² mAh / cm ^2, an electrode layer having a thickness of 48 μm, and a porosity of 22%.

3. Preparation of Battery

The electrode prepared above was prepared by punching in a circle of 1.4875 cm ² . A lithium metal thin film cut into a round shape of 1.7671 cm ² was prepared as a counter electrode. A coin-type half-cell was prepared by placing the solid electrolyte membrane obtained in Example 1 between the two electrodes.

Example 2

A solid electrolyte membrane was prepared in the same manner as in Example 1, except that HAuCl ₄ .3H ₂ O had a concentration of 5 wt% when preparing the solid electrolyte layer.

Example 3

A solid electrolyte membrane having a structure laminated in the order of the first solid electrolyte layer, the suppression layer, the second solid electrolyte layer, the suppression layer, and the third solid electrolyte layer was prepared. The solid electrolyte membrane of Example 3 is a structure in which the suppression layer and the third solid electrolyte layer are further added in the electrolyte layer of Example 1, and only the laminated structure is different, and the manufacturing method of each layer is the same as that of Example 1.

Example 4

A solid electrolyte membrane was prepared in the same manner as in Example 1 except that H ₂ PtCl ₆ .H ₂ O was used as a material for the suppression layer in preparing the solid electrolyte membrane.

Comparative Example 1

A solid electrolyte membrane was prepared in the same manner as in Example 1, except that no suppression layer was inserted in the preparation of the solid electrolyte membrane.

Comparative Example 2

The preparation was carried out in the same manner as in Example 1, except that the salt concentration was 10 wt% and the spin coating was performed at 300 rpm.

Comparative Example 3

In preparing a solid electrolyte layer, the same process as in Comparative Example 1 was performed except that a total of three solid electrolyte layers without a suppression layer were laminated.

Experimental Example  One: Solid electrolyte layer  Ion Conductivity Evaluation

The solid electrolyte membrane produced in each Example and Comparative Example was cut | disconnected in the circular shape of 1.7671 cm <^2> . Coin cells were manufactured by placing them between two sheets of stainless steel (SUS). An electrochemical impedance was measured using an analytical device (VMP3, Bio logic science instrument) at 60 ° C. under an amplitude of 10 mV and a scan range of 500 KHz to 20 MHz. Based on this, the ion conductivity was calculated.

Experimental Example  2: Evaluation of initial discharge capacity and lifetime characteristics

The batteries prepared in Examples 1 to 4 and Comparative Examples 1 to 3 were charged and discharged at 0.05 ° C. at 60 ° C. to evaluate initial discharge capacity discharge.

Charging Conditions: CC (Constant Current) / CV (Constant Voltage), (4.15V, 0.005C current cut-off)

Discharge condition: CC (constant current) condition 3V, (0.05C)

On the other hand, the time of occurrence of short circuit was charged and discharged at 0.1C, and it was judged as the time of abnormal behavior (unstable voltage change) of the voltage during charging during life evaluation.

Ion conductivity
(S / cm, 60 ℃)
Discharge capacity
(mAh / g, 4.15V)
When does a short circuit occur
(cycle)   Example 1 1 x 10 ^-4   159   18   Example 2 9x10 ^-5   155   20   Example 3 9x10 ^-5   142   23   Example 4 1 x 10 ^-4   156   16   Comparative Example 1 1 x 10 ^-4   156   5   Comparative Example 2 8 x 10 ^-6   -   -   Comparative Example 3 9x10 ^-5   145  8

As can be seen in Table 1, the battery including the solid electrolyte membranes of Examples 1 to 3 of the present invention was found to have a higher ion conductivity and discharge capacity than the battery of the comparative example, and a short circuit occurrence time was also delayed.

[Description of the code]

10 all-solid-state battery, 11 current collector, 12 positive electrode, 13 solid electrolyte membrane, 14 negative electrode (lithium metal), 14a dendrites

130 solid electrolyte membrane, 131 second solid electrolyte layer, 132 suppression layer, 133 first solid electrolyte layer

200 all-solid-state battery, 210 current collector, 220 positive electrode, 231 second solid electrolyte layer, 232 suppression layer, 233 first solid electrolyte layer, 240 negative electrode (lithium metal), 241 dendrites

330 solid electrolyte membrane, 331 solid electrolyte layer, 332 suppression layer

Claims (11)

As a solid electrolyte membrane for an all-solid-state battery,
The solid electrolyte membrane has an ionic conductivity of 1x10 ^-5 S / cm or more,
The solid electrolyte membrane includes at least one suppression layer comprising a dendrite growth inhibitory substance (a), wherein the dendrite growth inhibitory substance (a) is (a1) metal (s) having a lower ionization tendency than lithium and (a2) A solid electrolyte membrane, which is derived from any one of two or more alloy (s) of the metals and is included in the suppression layer in the form of at least one of salts and ions thereof.
The method of claim 1,
The metal is K, Sr, Ca, Na, Mg, Be, Al, Mn, Zn, Cr (+3), Fe, Cd, Co, Ni, Sn, Pb, Cu, Hg, Ag, Pd, Ir, Pt A solid electrolyte membrane comprising at least one selected from the group consisting of (+2), Au and Pt (+4).
The method of claim 2,
The inhibitor is a solid electrolyte membrane comprising at least one selected from the group consisting of Au and Pt.
The method of claim 1,
The metal salt is one of chloride, iodide, cyanide, bormide, sulfide, hydroxide, phosphite and chloride hydrate. It is more than that, a solid electrolyte membrane.
The method of claim 1,
The solid electrolyte membrane comprises at least two solid electrolyte layers and at least one suppression layer, wherein the suppression layer is disposed between the solid electrolyte layer.
The method of claim 5,
The solid electrolyte membrane is a solid electrolyte membrane that the first solid electrolyte layer, the suppression layer and the second solid electrolyte layer is sequentially stacked.
The method of claim 5,
At least one of the two or more solid electrolyte layers includes an inhibitor, and the content (weight%) of the inhibitor in each solid electrolyte layer is lower than the content (weight%) of the inhibitor included in the inhibitor layer. .
The method of claim 1,
Wherein said solid electrolyte membrane comprises an ion conductive solid electrolyte material, and said ion conductive solid electrolyte material comprises a polymer solid electrolyte, an inorganic solid electrolyte, or a mixture of both.
The method of claim 8,
The polymer solid electrolyte is a solid electrolyte membrane comprising a polymer resin and a solvated lithium salt.
An all-solid-state battery comprising a negative electrode, a positive electrode, and a solid electrolyte membrane interposed between the negative electrode and the positive electrode, wherein the negative electrode comprises lithium metal, and the solid electrolyte membrane is according to claim 1, an electrochemical device.
The method of claim 10,
The solid electrolyte membrane is formed by sequentially stacking a first solid electrolyte layer, a suppression layer, and a second solid electrolyte layer. The first solid electrolyte layer includes an inhibitor material (a), and the inhibitor material is lower than (a1) lithium. An electrochemical device derived from any one of metal (s) having low ionization tendency and (a2) alloy (s) of two or more of the metals, wherein the first solid electrolyte layer faces a cathode.

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