KR20230086622A - Method for preparing polymer solid electrolyte and polymer solid electrolyte prepared therefrom - Google Patents

Abstract

The present invention relates to a method for preparing a polymer solid electrolyte and a polymer solid electrolyte prepared therefrom, and more particularly, in preparing the polymer solid electrolyte, a polymer having poor miscibility with each other as a raw material and a non-volatile liquid phase A liquid membrane and a polymer electrolyte membrane can be formed by a phase separation phenomenon that occurs when the compounds are mixed and dried, and the polymer electrolyte membrane can be obtained in the form of a uniform thin film.

Description

Manufacturing method of polymer solid electrolyte and polymer solid electrolyte prepared therefrom

The present invention relates to a method for preparing a polymer solid electrolyte and a polymer solid electrolyte prepared therefrom.

Various batteries capable of overcoming the limitations of current lithium secondary batteries are being studied in terms of battery capacity, safety, output, large size, and miniaturization.

Representatively, metal-air batteries with a very large theoretical capacity in terms of capacity compared to current lithium secondary batteries, all solid batteries with no risk of explosion in terms of safety, and supercapacitors in terms of output ( Supercapacitor), NaS battery or RFB (redox flow battery) in terms of large size, and thin film battery in terms of miniaturization, continuous research is being conducted.

Among them, the all-solid-state battery refers to a battery that replaces the liquid electrolyte used in conventional lithium secondary batteries with a solid one, and it does not use a flammable solvent in the battery, so there is no ignition or explosion due to the decomposition reaction of the conventional electrolyte, so it is safe. can be greatly improved. In addition, since Li metal or Li alloy can be used as a negative electrode material, there is an advantage in that the energy density for the mass and volume of the battery can be dramatically improved.

As described above, the all-solid-state battery is attracting attention as a next-generation lithium secondary battery from the viewpoint of safety, high energy density, high output, and simplification of manufacturing process.

However, such an all-solid-state battery has a problem in that a dead space, that is, a void without ionic conductivity, occurs at the interface between the electrode and the solid electrolyte because both the electrode and the solid electrolyte are solid and there is no liquid electrolyte.

In addition, the demand for thin-film solid electrolytes is increasing with the thinning of batteries, but the strength of the solid electrolyte is weakened as it is thinned, so it is not easy to separate from the release film attached during the manufacturing process, and the thin film is damaged.

Accordingly, there is a demand for technology development capable of producing a solid electrolyte in the form of a uniform thin film.

Japanese Laid-open Patent No. 2020-526897

As a result of various studies to solve the above problems, the inventors of the present invention have found that when preparing a polymer solid electrolyte, by using a polymer and a non-volatile liquid compound having poor miscibility with each other as raw materials, they can be mixed and dried. It was confirmed that a liquid film and a polymer solid electrolyte film formed by the phase separation phenomenon that occurs when the liquid phase is formed, and the polymer solid electrolyte film exhibits a uniform thin film shape.

Accordingly, an object of the present invention is to provide a method for preparing a polymer solid electrolyte in the form of a uniform thin film and a polymer solid electrolyte prepared therefrom.

The present invention relates to a method for manufacturing a polymer solid electrolyte, which includes (S1) a solution for forming a polymer solid electrolyte by adding a polymer, a non-volatile liquid compound, and a lithium salt to a solvent. Preparing; (S2) forming a coating layer by applying the polymer solid electrolyte forming solution on a substrate; (S3) drying the coating layer to phase-separate the liquid membrane and the polymer solid electrolyte membrane; and (S4) separating the polymer solid electrolyte membrane.

The liquid film includes the non-volatile liquid compound, the polymer solid electrolyte film includes the polymer and a lithium salt, the non-volatile liquid compound is immiscible with the polymer, and the liquid film is formed on a substrate and the polymer solid electrolyte membrane may be formed on the liquid membrane.

The weight ratio of the polymer and the non-volatile liquid compound may be 1:0.8 to 1:5.5.

The polymer may include at least one selected from the group consisting of polypropylene carbonate (PPC), polyacrylonitrile (PAN), and polyvinylpyrrolidone (PVP).

The non-volatile liquid compound may include at least one selected from the group consisting of polyhedral oligomeric silsesquioxane (POSS) and ionic liquid.

The POSS includes one or more functional groups (functional groups, R), and the functional groups are functional groups containing one or more elements selected from O, N, S, Si, and P, or may bind to lithium ions. It may be a functional group with

The functional group is polyethylene glycol (poly(ethylene glycol), PEG), alcohol (alcohol), amine (amine), carboxylic acid (carboxylic acid), allyl (allyl), epoxide (epoxide), thiol (thiol), silane (silane) ) or silanol.

The ionic liquid includes a cation and an anion, and the cation is imidazolium, pyrazolium, triazolium, thiazolium, oxazolium, pyridazinium, pyrid, substituted or unsubstituted by an alkyl group having 1 to 15 carbon atoms. At least one selected from the group consisting of midinium, pyrazinium, ammonium, phosphonium, pyridinium and pyrrolidinium,

The anion is PF ₆ ^- , BF ₄ ^- , CF ₃ SO ₃ ^- , N(CF ₃ SO ₂ ) ₂ ^- , N(C ₂ F ₅ SO ₂ ) ₂ ^- , C(CF ₂ SO ₂ ) ₃ ^- , AsF ₆ ^- , SbF ₆ ^- , AlCl ₄ ^- , NbF ₆ ^- , HSO ₄ ^- , ClO ₄ ^- , CH ₃ SO ₃ ^- and CF ₃ CO ₂ ^- may include one or more selected from the group consisting of.

The lithium salt is LiTFSI (Lithium bis(trifluoromethanesulphonyl)imide), LiFSI (Lithium bis(fluorosulfonyl)imide), LiNO ₃ , LiOH, LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAsF ₆ , LiSbF ₆ , LiAlCl ₄ , CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, LiSCN, LiC(CF ₃ SO ₂ ) ₃ , (CF ₃ SO ₂ ) ₂ NLi and (FSO ₂ ) ₂ It may include one or more selected from the group consisting of NLi.

The substrate is stainless steel. It may include one or more selected from the group consisting of Cu foil and Al foil.

The method of forming the coating layer is bar coating, roll coating, spin coating, slit coating, die coating, blade coating, comma It may be comma coating, slot die coating, lip coating, or solution casting.

The weight ratio of the polymer and the lithium salt may be 1:0.5 to 1:3.

The solvent is propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propionate (MP), Dimethyl sulfoxide, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), vinylene carbonate (VC), gamma butyrolactone (GBL) , fluoroethylene carbonate (FEC), methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, pentyl acetate, methyl propionate, ethyl propionate, including at least one selected from the group consisting of ethyl propionate and butyl propionate it may be

Drying of the coating layer may be performed at 150° C. or less.

The present invention also provides a polymer solid electrolyte comprising the polymer and a lithium salt.

The polymer solid electrolyte may have a thickness of 23 μm to 35 μm.

The thickness deviation of the polymer solid electrolyte is 0.7 μm or less, and the thickness deviation is determined by measuring the thickness at 9 locations in a 3 x 3 cm 2 punched polymer solid electrolyte sample, and the deviation between the thickest and thinnest thickness may have been calculated.

The polymer solid electrolyte may be in the form of a freestanding film.

The polymer solid electrolyte may have ionic conductivity of 1.2 x 10 ^-5 to 4.5 x 10 ^-5 S/cm, and the ionic conductivity may be measured at 80°C.

The present invention also provides an all-solid-state battery including the polymer solid electrolyte.

The present invention is also a polymer solid electrolyte, wherein the thickness of the polymer solid electrolyte is 23 μm to 35 μm, the thickness deviation of the polymer solid electrolyte is 0.7 μm or less, and the thickness deviation is a polymer punched at 3 x 3 cm 2 The thickness was measured at 9 locations in the solid electrolyte sample, and the deviation between the thickest and thinnest thickness was calculated, the polymer solid electrolyte was in the form of a freestanding film, and the ionic conductivity of the polymer solid electrolyte is 1.2 x 10 ^-5 to 4.5 x 10 ^-5 S/cm, which provides a polymer solid electrolyte.

According to the present invention, in the polymer solid electrolyte manufacturing process, a polymer and a non-volatile liquid compound that are not miscible with each other are used as raw materials, and the polymer and the non-volatile liquid compound are mixed and then phase-separated during drying. Thus, a polymer solid electrolyte in the form of a uniform thin film can be prepared by forming a laminate in which a liquid membrane and a polymer solid electrolyte membrane are stacked and then separating them.

In addition, in the polymer solid electrolyte manufacturing process, when the polymer solid electrolyte membrane is separated from the substrate after the liquid membrane and the polymer solid electrolyte membrane are formed on the substrate, there is no resistance due to the liquid membrane adjacent to the substrate. The polymer solid electrolyte membrane may be separated.

1 is a schematic diagram showing a process of manufacturing a polymer solid electrolyte according to an embodiment of the present invention.
2 is a schematic diagram showing the structure of a laminate including a liquid membrane and a polymer solid electrolyte membrane formed during a polymer solid electrolyte manufacturing process according to an embodiment of the present invention.
3 is a schematic view of a sample for measuring the uniformity of a polymer solid electrolyte prepared according to an embodiment of the present invention.

Hereinafter, the present invention will be described in more detail to aid understanding of the present invention.

Terms or words used in this specification and claims should not be construed as being limited to ordinary or dictionary meanings, and the inventor may appropriately define the concept of terms in order to explain his or her invention in the best way. It should be interpreted as a meaning and concept consistent with the technical idea of the present invention based on the principle that there is.

As used herein, the term "miscibility" refers to the property of not mixing with each other.

As used herein, the term "free-standing film" refers to a film capable of maintaining a film shape by itself without a separate support at room temperature and pressure.

Manufacturing method of polymer solid electrolyte

The present invention relates to a method for preparing a polymer solid electrolyte, comprising: (S1) preparing a solution for forming a polymer solid electrolyte by adding a polymer, a non-volatile liquid compound, and a lithium salt to a solvent; (S2) forming a coating layer by applying the polymer solid electrolyte forming solution on a substrate; (S3) drying the coating layer to phase-separate the liquid membrane and the polymer solid electrolyte membrane; and (S4) separating the polymer solid electrolyte membrane, wherein the non-volatile liquid compound is immiscible with the polymer, the liquid membrane includes the non-volatile liquid compound, and the polymer solid The electrolyte membrane includes the polymer and lithium salt.

In the manufacturing method of the polymer solid electrolyte, a polymer having poor miscibility with each other and a non-volatile liquid compound are used as raw materials. When the polymer and the non-volatile liquid compound are mixed and then dried, a phase separation phenomenon occurs, so that a liquid film containing the non-volatile liquid compound and a polymer solid electrolyte film containing the polymer may be formed. After forming a laminate in which the solid electrolyte membranes are stacked in order, the polymer solid electrolyte membrane may be separated to obtain a polymer solid electrolyte. At this time, since the liquid membrane is formed between the substrate and the polymer solid electrolyte membrane, the polymer solid electrolyte membrane can be easily separated without resistance.

1 is a schematic diagram showing a manufacturing method of a polymer solid electrolyte according to an embodiment of the present invention, and FIG. 2 includes a liquid membrane and a polymer solid electrolyte membrane formed during a manufacturing process of a polymer solid electrolyte according to an embodiment of the present invention. As a schematic diagram showing the structure of a laminate, the manufacturing method of the polymer solid electrolyte according to the present invention will be described in detail in each step with reference to these drawings.

In the present invention, in the step (S1), a polymer, a non-volatile liquid compound, and a lithium salt may be added to a solvent to prepare a solution for forming a polymer solid electrolyte.

The polymer can form a polymer solid electrolyte in the form of a uniform thin film without deteriorating electrical conductivity and ionic conductivity of the polymer solid electrolyte.

In addition, the polymer is not particularly limited as long as it exhibits incompatible characteristics with respect to the non-volatile liquid compound included in the liquid film, and the polymer is, for example, polypropylene carbonate (PPC), polyacrylic acid. It may include at least one member selected from the group consisting of polyacrylonitrile (PAN) and polyvinylpyrrolidone (PVP).

The non-volatile liquid compound exhibits a property of being immiscible with the polymer, and may be phase separated from the polymer during the manufacturing process of the polymer solid electrolyte to form a liquid film in the form of a separate layer.

In addition, the non-volatile liquid compound may include POSS (Polyhedral Oligomeric Silsesquioxane) and/or an ionic liquid.

The POSS is a polyhedral oligosilsesquioxane, and includes one or more functional groups (R), and the functional group (R) is one or more elements selected from O, N, S, Si, and P. It is a functional group containing, or includes a functional group capable of bonding with lithium ions. For example, the functional group (R) is polyethylene glycol (poly (ethylene glycol), PEG), alcohol (alcohol), amine (amine), carboxylic acid (carboxylic acid), allyl (allyl), epoxide (epoxide), It may be thiol, silane, silanol, glycidyl, octasilane or methacryl.

In addition, the POSS may be PEG-POSS containing ethylene glycol (PEG) as a functional group (R), and when the PEG-POSS is used, phase separation of the polymer may be more smoothly performed. For example, in the case of using PPC and PEG-POSS, phase separation can be performed smoothly, thereby improving process efficiency.

In addition, POSS may be in a solid or liquid state depending on the functional group (R). In order to achieve smooth phase separation with the polymer, it may be advantageous to use liquid POSS, and the liquid POSS may include the functional group (R) as described above. Preferably, the liquid POSS is PEG- It can be POSS.

In the present invention, the liquid POSS may be represented by Formula 1 below:

[Formula 1]

In Formula 1,

R are the same as or different from each other, and are each independently selected from the group consisting of groups represented by the following formulas 1-1 to 1-4:

[Formula 1-1]

[Formula 1-2]

[Formula 1-3]

[Formula 1-4]

In Formulas 1-1 to 1-4,

L1 to L5 are C1 to C30 alkylene groups,

R1 to R4 are hydrogen; hydroxy group; amino group; thiol group; C1 to C30 alkyl group; C2 to C30 alkenyl group; C2 to C30 alkynyl group; C1 to C30 alkoxy group; And C1 to C30 carboxyl group; selected from the group consisting of,

m and n are the same as or different from each other, and each independently represents an integer from 0 to 10;

* is a binding position.

In one embodiment of the present invention, in Chemical Formulas 1-1 to 1-4, L1 to L5 are C1 to C10 alkylene groups, R1 to R4 are hydrogen; hydroxy group; Or an alkyl group of C1 to C30, m and n are the same as or different from each other, and each independently represents an integer of 0 to 10.

In one embodiment of the present invention, the functional group R in Formula 1 is selected from the group consisting of a polyethylene glycol group, a glycidyl group, an octasilane group and a methacryl group.

In addition, the ionic liquid includes a cation and an anion, and the cation is imidazolium, pyrazolium, triazolium, thiazolium, oxazolium, pyridazinium unsubstituted or substituted by an alkyl group having 1 to 15 carbon atoms. , pyrimidinium, pyrazinium, ammonium, phosphonium, pyridinium, and at least one selected from the group consisting of pyrrolidinium, wherein the anion is PF ₆ ^- , BF ₄ ^- , CF ₃ SO ₃ ^- , N (CF ₃ SO ₂ ) ₂ ^- , N(C ₂ F ₅ SO ₂ ) ₂ ^- , C(CF ₂ SO ₂ ) ₃ ^- , AsF ₆ ^- , SbF ₆ ^- , AlCl ₄ ^- , NbF ₆ ^- , HSO ₄ ^- , ClO ₄ ^- , CH ₃ SO ₃ ^- and CF ₃ CO ₂ ^- may include one or more selected from the group consisting of. For example, the ionic liquid is 1-ethyl-3-methyl imidazolium, 1-butyl-3-methyl imidazolium ), 1-Butyl-1-methyl pyrrolidinium, 1-methyl-1-propyl piperidinium, bis(trifluoromethyl) It may include at least one selected from the group consisting of sulfonyl) imide (bis (trifluoromethylsulfonyl) imide, TFSI) and trifluoromethanesulfonate.

The lithium salt may impart ion conductivity to the polymer solid electrolyte and improve ion conductivity without reducing electrical conductivity by the electrically conductive polymer.

In addition, the lithium salt is LiTFSI (Lithium bis(trifluoromethanesulphonyl)imide), LiFSI (Lithium bis(fluorosulfonyl)imide), LiNO ₃ , LiOH, LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAsF ₆ , LiSbF ₆ , LiAlCl ₄ , CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, LiSCN, LiC(CF ₃ SO ₂ ) ₃ , (CF ₃ SO ₂ ) ₂ It may contain at least one selected from the group consisting of NLi, (FSO ₂ ) ₂ NLi, lithium chloroborane, lithium lower aliphatic carbonate, and lithium 4-phenyl borate.

The weight ratio of the polymer and the non-volatile liquid compound may be 1:0.8 to 1:5.5, specifically, 1:0.8 or less, 1:0.9 or less, or 1:1 or less, 1:5 or more, 1:5.2 or greater than or equal to 1:5.5. When the weight ratio exceeds 1:0.8, the polymer solid electrolyte in the form of a free standing film is prepared in a state in which the polymer and the non-volatile liquid compound are simply mixed without causing phase separation because the content of the polymer is excessively increased, and the polymer The uniformity and ionic conductivity of the solid electrolyte may be lowered. In addition, when the weight ratio is less than 1:5.5, the content of the non-volatile liquid compound is excessively high, so that a solid polymer electrolyte may not be prepared and a liquid electrolyte may be prepared.

In addition, the weight ratio of the polymer and the lithium salt may be 1:0.5 to 1:3, specifically, 1:0.5 or less, 1:0.6 or less, or 1:0.7 or less, 1:1.5 or more, 1:2 or more, or It may be 1:3 or higher. If the weight ratio is greater than 1:0.5, the content of the polymer may be excessively increased and the ionic conductivity of the polymer solid electrolyte may be lowered. If the weight ratio is less than 1:3, the content of the lithium salt may be excessively increased, preventing formation of a polymer electrolyte membrane. there is.

The solvent is not particularly limited as long as it is a solvent used for preparing an electrolyte in the art. For example, the solvent is propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propionate (MP), dimethyl sulfoxide, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethylmethyl carbonate (EMC), vinylene carbonate (VC), gamma butyro 1 selected from the group consisting of lactone (GBL), fluoroethylene carbonate (FEC), methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, pentyl acetate, methyl propionate, ethyl propionate, ethyl propionate and butyl propionate May include more than one species.

The concentration of the solution for forming the polymer solid electrolyte is not particularly limited, and is not particularly limited as long as the concentration is sufficient to perform the coating process. For example, the concentration of the solution for forming the polymer solid electrolyte may be 10 to 40% by weight, specifically 10% by weight or more, 15% by weight or more, or 20% by weight or more, 30% by weight or less, 35% by weight or more % or less or 40% or less by weight. Within the above range, it can be appropriately adjusted to a concentration sufficient to perform the coating process.

In addition, the solution for forming the polymer solid electrolyte is a mixture of a liquid moiety and a polymer chain.

The liquid moiety is derived from the non-volatile liquid compound, and the polymer chain is derived from the polymer. Since the non-volatile liquid compound and the polymer do not mix with each other, the non-volatile liquid compound and the polymer exist separately in the solution.

In the present invention, in the step (S2), the coating layer may be formed by applying the polymer solid electrolyte forming solution on a substrate.

The substrate may be in the form of a foil, and the foil may be in the form of a thin film of metal such as aluminum, copper or stainless steel. By using a foil in the form of a metal thin film as the substrate, it may be advantageous to manufacture a solid electrolyte in the form of a free-standing film.

In addition, the coating method includes bar coating, roll coating, spin coating, slit coating, die coating, blade coating, and comma coating. (comma coating), slot die coating (slot die coating), lip coating (lip coating) or solution casting (solution casting), but it may be, but is not limited thereto as long as it is a coating method capable of forming a coating layer on the substrate.

In the present invention, in the step (S3), the coating layer may be dried to separate the coating layer into a liquid membrane and a polymer electrolyte membrane.

The drying is not particularly limited as long as the drying method can induce phase separation between the liquid portion and the polymer chain included in the coating layer. For example, the drying may be performed at 150°C or less, 130°C or less, or 110°C or less.

The phase separation may occur due to the fact that the polymer as a raw material and the non-volatile liquid compound are incompatible with each other.

As shown in FIG. 2, a liquid film 20 containing the non-volatile liquid compound is formed on a substrate 10, and a polymer solid electrolyte film containing a polymer and a lithium salt is formed on the liquid film 20. (30) can be formed.

In the present invention, in the step (S4), the polymer solid electrolyte membrane may be separated.

In general, as the polymer solid electrolyte membrane is thinned, its strength is weakened, and thus it may be difficult to separate it from the substrate. However, since a liquid film is formed between the substrate and the polymer solid electrolyte membrane in the step (S3), the polymer solid electrolyte membrane can be separated from the substrate without additional resistance.

In addition, after separating the polymer solid electrolyte membrane, a cleaning step for removing non-volatile liquid compounds remaining in the polymer solid electrolyte membrane may be additionally performed.

polymer solid electrolyte

The present invention also provides a polymer solid electrolyte prepared by the method for manufacturing a polymer solid electrolyte as described above.

The polymer solid electrolyte includes a polymer and a lithium salt. The type and weight ratio of the polymer and the lithium salt are the same as described above.

In the present invention, the thickness of the polymer solid electrolyte may be 23 μm to 35 μm, and the thickness may be reduced compared to general polymer solid electrolytes to represent a thin film solid electrolyte. If the thickness is less than 23 μm, durability of the polymer solid electrolyte may deteriorate, and if the thickness exceeds 35 μm, it may act as a resistance during battery operation.

In addition, the thickness deviation of the polymer solid electrolyte may be 0.7 μm or less, and the smaller the thickness deviation within the above range, the better the uniformity. If the thickness deviation exceeds 0.7 μm, the uniformity of the polymer solid electrolyte is poor. For example, the thickness deviation is measured between the thickness at the thickest position and the thickness at the thinnest position by measuring the thickness at a total of nine designated positions with respect to the sample punched out with the polymer solid electrolyte in a size of 3 * 3 cm 2 The deviation of was calculated. The smaller the deviation of the calculated thickness, the more uniform it was determined.

In the present invention, the polymer solid electrolyte may be in the form of a free standing film.

The polymer solid electrolyte in the form of a free-standing film maintains a film form by itself at room temperature and normal pressure, and can be applied for various purposes.

In the present invention, the ionic conductivity of the polymer solid electrolyte is 1.2 x 10 ^-5 to 4.5 x 10 ^-5 S/cm, and the ionic conductivity may be measured at 80°C. When applied to an all-solid-state battery, the polymer solid electrolyte having ionic conductivity can improve stability and simultaneously improve battery performance and lifespan.

all-solid-state battery

The present invention also relates to an all-solid-state battery including the polymer solid electrolyte described above, and the all-solid battery may include a positive electrode and a negative electrode and the polymer solid electrolyte interposed therebetween.

In addition, the polymer solid electrolyte may be applied to an electrode and included in an all-solid-state battery in a state of being attached to one surface of an anode or a cathode.

In the present invention, the positive electrode includes a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector.

The cathode active material layer includes a cathode active material, a binder, and a conductive material.

The positive electrode active material is not particularly limited as long as it is a material capable of reversibly occluding and releasing lithium ions, and examples thereof include lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), Li[Ni _x Co _y Mn _z M _v ] O ₂ (Wherein, M is any one or two or more elements selected from the group consisting of Al, Ga and In; 0.3≤x<1.0, 0≤y, z≤0.5, 0≤ v≤0.1, x+y+z+v=1), Li(Li _a M _ba-b' M'_b' )O _2-c A _c (wherein 0≤a≤0.2, 0.6≤b≤ 1, 0≤b'≤0.2, 0≤c≤0.2; M includes Mn and at least one selected from the group consisting of Ni, Co, Fe, Cr, V, Cu, Zn, and Ti; M 'is at least one member selected from the group consisting of Al, Mg and B, and A is at least one member selected from the group consisting of P, F, S and N), layered compounds or one or more transition metals such as A compound substituted with; lithium manganese oxides such as Li _1+y Mn _2-y O ₄ (where y is 0 - 0.33), LiMnO ₃ , LiMn ₂ O ₃ , LiMnO ₂ ; lithium copper oxide (Li ₂ CuO ₂ ); vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ , and Cu ₂ V ₂ O ₇ ; Ni site type lithium nickel oxide represented by the formula LiNi _1-y MyO ₂ (wherein M=Co, Mn, Al, Cu, Fe, Mg, B or Ga and y=0.01 - 0.3); Formula LiMn _2-y M _y O ₂ (wherein M=Co, Ni, Fe, Cr, Zn or Ta and y=0.01 - 0.1) or Li ₂ Mn ₃ MO ₈ (wherein M=Fe, Co, Ni, Cu or Zn) lithium manganese composite oxide; LiMn ₂ O ₄ in which Li part of the formula is substituted with an alkaline earth metal ion; disulfide compounds; Fe ₂ (MoO ₄ ) ₃ etc. are mentioned, but it is not limited only to these.

The positive electrode active material may be included in an amount of 40 to 80% by weight based on the total weight of the positive electrode active material layer. Specifically, the content of the cathode active material may be 40% by weight or more or 50% by weight or more, and may be 70% by weight or less or 80% by weight or less. If the content of the cathode active material is less than 40% by weight, connectivity between the wet cathode active material layer and the dry cathode active material layer may be insufficient, and if the content of the cathode active material is greater than 80% by weight, mass transfer resistance may increase.

In addition, the binder is a component that assists in the bonding of the positive electrode active material and the conductive material and the bonding to the current collector, styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile copolymer, acrylonitrile-butadiene rubber, nitrile Butadiene rubber, acrylonitrile-styrene-butadiene copolymer, acrylic rubber, butyl rubber, fluorine rubber, polytetrafluoroethylene, polyethylene, polypropylene, ethylene/propylene copolymer, polybutadiene, polyethylene oxide, chlorosulfonated polyethylene , polyvinylpyrrolidone, polyvinylpyridine, polyvinyl alcohol, polyvinyl acetate, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, latex, acrylic resin, phenolic resin, epoxy resin, carboxymethylcellulose , hydroxypropyl cellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylcellulose, cyanoethylsucrose, polyester, polyamide, polyether, polyimide, polycarboxylate, polycarboxylic acid, consisting of polyacrylic acid, polyacrylate, lithium polyacrylate, polymethacrylic acid, polymethacrylate, polyacrylamide, polyurethane, polyvinylidene fluoride and poly(vinylidene fluoride)-hexafluoropropene It may contain one or more selected from the group. Preferably, the binder may include at least one selected from the group consisting of styrene-butadiene rubber, polytetrafluoroethylene, carboxymethylcellulose, polyacrylic acid, lithium polyacrylate, and polyvinylidene fluoride.

In addition, the binder may be included in an amount of 1 wt% to 30 wt% based on the total weight of the positive electrode active material layer, and specifically, the content of the binder may be 1 wt% or more or 3 wt% or more, and 15 wt% or less than or equal to 30% by weight. If the content of the binder is less than 1% by weight, the adhesive strength between the positive electrode active material and the positive electrode current collector may be reduced, and if the content exceeds 30% by weight, the adhesive strength is improved, but the content of the positive electrode active material is reduced accordingly, and battery capacity may be lowered.

In addition, the conductive material is not particularly limited as long as it prevents side reactions in the internal environment of the all-solid-state battery and has excellent electrical conductivity without causing chemical change in the battery. Typically, graphite or conductive carbon can be used, For example, graphite, such as natural graphite and artificial graphite; carbon black such as carbon black, acetylene black, ketjen black, denka black, thermal black, channel black, furnace black, lamp black, and summer black; a carbon-based material whose crystal structure is graphene or graphite; conductive fibers such as carbon fibers and metal fibers; fluorinated carbon; metal powders such as aluminum powder and nickel powder; conductive whiskeys such as zinc oxide and potassium titanate; conductive oxides such as titanium oxide; And conductive polymers such as polyphenylene derivatives; may be used alone or in combination of two or more, but are not necessarily limited thereto.

The conductive material may be typically included in an amount of 0.5% to 30% by weight based on the total weight of the cathode active material layer, and specifically, the content of the conductive material may be 0.5% by weight or more or 1% by weight or more, and 20% by weight or less or may be up to 30% by weight. If the content of the conductive material is too small, less than 0.5% by weight, it is difficult to expect an effect of improving electrical conductivity or the electrochemical properties of the battery may be deteriorated. Capacity and energy density may be lowered. A method of including the conductive material in the positive electrode is not particularly limited, and a conventional method known in the art, such as coating on a positive electrode active material, may be used.

In addition, the cathode current collector supports the cathode active material layer and serves to transfer electrons between an external conductor and the cathode active material layer.

The positive current collector is not particularly limited as long as it does not cause chemical change in the all-solid-state battery and has high electronic conductivity. For example, copper, stainless steel, aluminum, nickel, titanium, palladium, calcined carbon, copper or stainless steel surface treated with carbon, nickel, silver, etc., aluminum-cadmium alloy, etc. may be used as the anode current collector. can

The cathode current collector may have a fine concavo-convex structure or a 3-dimensional porous structure on the surface of the cathode current collector in order to enhance bonding strength with the cathode active material layer. Accordingly, the cathode current collector may include various forms such as a film, sheet, foil, mesh, net, porous material, foam, and nonwoven fabric.

The positive electrode as described above may be prepared according to a conventional method, and specifically, a composition for forming a positive electrode active material layer prepared by mixing a positive electrode active material, a conductive material, and a binder in a solvent is applied and dried on a positive electrode current collector, and optionally In order to improve the density of the positive electrode, it may be manufactured by compression molding the positive electrode current collector. At this time, it is preferable to use a solvent capable of uniformly dispersing the cathode active material, the binder, and the conductive material and easily evaporating as the solvent. Specifically, acetonitrile, methanol, ethanol, tetrahydrofuran, water, isopropyl alcohol, etc. are mentioned.

In the present invention, the negative electrode includes a negative electrode current collector and a negative electrode active material layer formed on the negative electrode current collector. The anode active material layer includes an anode active material, a binder, and a conductive material.

The anode active material includes a material capable of reversibly intercalating or deintercalating lithium (Li ⁺ ), a material capable of reacting with lithium ions to reversibly form a lithium-containing compound, lithium metal, or a lithium alloy. can include

The material capable of reversibly intercalating or deintercalating lithium ions (Li ⁺ ) may be, for example, crystalline carbon, amorphous carbon, or a mixture thereof. A material capable of reversibly forming a lithium-containing compound by reacting with the lithium ion (Li ⁺ ) may be, for example, tin oxide, titanium nitrate, or silicon. The lithium alloy is, for example, lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium ( It may be an alloy of a metal selected from the group consisting of Ca), strontium (Sr), barium (Ba), radium (Ra), aluminum (Al), and tin (Sn).

Preferably, the negative electrode active material may be lithium metal, and specifically, may be in the form of a lithium metal thin film or lithium metal powder.

The negative active material may be included in an amount of 40 to 80% by weight based on the total weight of the negative active material layer. Specifically, the content of the negative electrode active material may be 40% by weight or more or 50% by weight or more, and may be 70% by weight or less or 80% by weight or less. If the content of the negative active material is less than 40% by weight, connectivity between the wet negative active material layer and the dry negative active material layer may be insufficient, and if the content is greater than 80% by weight, mass transfer resistance may increase.

In addition, the binder is as described above in the positive electrode active material layer.

In addition, the conductive material is as described above for the positive electrode active material layer.

In addition, the anode current collector is not particularly limited as long as it does not cause chemical change in the battery and has conductivity. For example, the anode current collector is copper, stainless steel, aluminum, nickel, titanium, burnt carbon, or copper. B. Surface treatment of carbon, nickel, titanium, silver, etc. on the surface of stainless steel, aluminum-cadmium alloy, etc. may be used. In addition, the anode current collector, like the cathode current collector, may be used in various forms such as a film, sheet, foil, net, porous material, foam, nonwoven fabric, etc. having fine irregularities formed on the surface thereof.

The manufacturing method of the negative electrode is not particularly limited, and may be prepared by forming a negative electrode active material layer on a negative electrode current collector using a method of forming a layer or film commonly used in the art. For example, methods such as compression, coating, and deposition may be used. In addition, a case in which a metal lithium thin film is formed on a metal plate by initial charging after assembling a battery in a state in which the lithium thin film is not present on the negative electrode current collector is also included in the negative electrode of the present invention.

Manufacturing of the all-solid-state battery having the above configuration is not particularly limited in the present invention, and a known method may be used.

In the manufacture of the all-solid-state battery of the present invention, electrodes including positive electrodes and negative electrodes are disposed and then pressed and molded to assemble a cell.

The assembled cell is installed in an exterior material and then sealed by heat compression or the like. As the exterior material, a laminated pack made of aluminum or stainless steel, or a cylindrical or rectangular metal container is suitable.

Hereinafter, preferred embodiments are presented to aid understanding of the present invention, but the following examples are merely illustrative of the present invention, and it is obvious to those skilled in the art that various changes and modifications are possible within the scope and spirit of the present invention. It goes without saying that changes and modifications fall within the scope of the appended claims.

In the following Examples and Comparative Examples, solid electrolytes were prepared according to the types and weight ratios of substrates, polymers, lithium salts, and solvents as shown in Table 1 below.

polymer solid electrolyte menstruum write polymer
non-volatile
liquid compound weight ratio
(PPC:PEG-POSS) lithium salt Example 1 SS Foil PPC PEG-POSS 1:1 LiTFSI NMP Example 2 SS Foil PPC PEG-POSS 1:2 LiTFSI NMP Example 3 SS Foil PPC PEG-POSS 1:5 LiTFSI NMP Comparative Example 1 SS Foil PPC - - LiTFSI NMP Comparative Example 2 PET release film PPC - - LiTFSI NMP Comparative Example 3 SS Foil PPC PEG-POSS 1:6 LiTFSI NMP Comparative Example 4 SS Foil PPC PEG-POSS 1:0.5 LiTFSI NMP

Example 1

As a raw material for preparing a polymer solid electrolyte, polypropylene carbonate (PPC) as a polymer, poly(ethylene glycol)-polyhedral oligomeric silsesquioxane (PEG-POSS) as a non-volatile liquid compound, LiTFSI as a lithium salt, and NMP as a solvent were prepared. . The polymer PPC, the non-volatile liquid compound PEG-POSS, and the lithium salt LiTFSI were used in a weight ratio of 1:1:1.

A solution for forming a polymer solid electrolyte having a concentration of 20% was prepared by adding the polymer, the non-volatile liquid compound, and the lithium salt to a solvent and mixing them.

The solution for forming the polymer solid electrolyte was bar-coated on a stainless steel (SS) foil as a substrate to form a coating layer.

After that, the coating layer was vacuum dried at 100°C. Phase separation occurred during drying, and a laminate was prepared in which a liquid film containing the non-volatile liquid compound and a polymer solid electrolyte film containing the polymer and lithium salt were sequentially formed on the SS foil. The SS foil was separated from the laminate to obtain a solid polymer electrolyte including a liquid film and a polymer solid electrolyte film formed on the liquid film.

Example 2

A polymer solid electrolyte was prepared in the same manner as in Example 1, except that the weight ratio of PPC and PEG-POSS used as the polymer and non-volatile liquid compound was 1:2.

Example 3

A polymer solid electrolyte was prepared in the same manner as in Example 1, except that the weight ratio of PPC and PEG-POSS used as the polymer and non-volatile liquid compound was 1:5.

Comparative Example 1

A polymer solid electrolyte was prepared in the same manner as in Example 1, except that the non-volatile liquid compound was not used.

Comparative Example 2

A polymer solid electrolyte was prepared in the same manner as in Example 1, except that a non-volatile liquid compound was not used and a PET (polyethylene terephthalate) release film was used instead of the SS foil as a substrate.

Comparative Example 3

A polymer solid electrolyte was prepared in the same manner as in Example 1, except that the weight ratio of PPC and PEG-POSS used as the polymer and non-volatile liquid compound was 1:6.

Comparative Example 4

A polymer solid electrolyte was prepared in the same manner as in Example 1, except that the weight ratio of PPC and PEG-POSS used as the polymer and non-volatile liquid compound was 1:0.5.

Experimental Example 1: Evaluation of polymer solid electrolyte

For the polymer solid electrolytes prepared in Examples and Comparative Examples, the possibility of forming a free-standing film, thickness, uniformity, and ionic conductivity were measured in the following manner, and the results are shown in Table 2 below.

(1) Availability of free standing film

It was confirmed whether the polymer solid electrolyte membrane could be separated from the substrate and obtained as a membrane, and whether the polymer solid electrolyte could form a free-standing film was evaluated.

(2) thickness

As shown in FIG. 3, the average thickness was calculated by measuring the thickness at a total of 9 designated positions for the sample punched out in the size of 3*3 cm 2 of the manufactured polymer solid electrolyte.

(3) Uniformity

Deviations between thicknesses were calculated based on the measured values of the total thickness of a total of 9 designated positions obtained in (2) above. The smaller the deviation of the calculated thickness, the more uniform it was determined.

(4) ionic conductivity

After contacting the polymer solid electrolyte sample obtained in (3) with an SS metal electrode having the same surface area as the sample, an AC voltage was applied through the electrodes on both sides of the sample at room temperature. At this time, the amplitude range of the measurement frequency of 0.01 Hz to 1 MHz was set as the applied condition, and the impedance was measured using BioLogic's VMP3. The resistance of the polymer solid electrolyte was obtained from the intersection (Rb) where the semicircle or straight line of the measured impedance trajectory meets the real axis, and the ionic conductivity of the polymer solid electrolyte at 80 ° C was calculated from the area and thickness of the sample.

[Equation 1]

σ: ionic conductivity

Rb: Intersection of the impedance locus with the real axis

A: the area of the sample

t: thickness of the sample

free standing film
shape availability thickness average
(μm) uniformity
(deviation, μm) ionic conductivity
(S/cm@80℃) Example 1 possible 28.8 0.63 1.2 E-05 Example 2 possible 32.3 0.67 2.6 E-05 Example 3 possible 24.7 0.47 4.5 E-05 Comparative Example 1 impossible - - - Comparative Example 2 possible 21.6 1.42 1.1 E-05 Comparative Example 3 Impossible (exists as Liquid, not membrane) not measurable not measurable - Comparative Example 4 Possible (no phase separation) 20.2 1.13 -

As shown in Table 2, the polymer solid electrolytes of Examples 1 to 3 prepared by using the polymer PPC and the non-volatile liquid compound PEG-POSS in an appropriate weight ratio were prepared in the form of a free-standing film Confirmation did In addition, it can be seen that the polymer solid electrolytes of Examples 1 to 3 were prepared uniformly with little variation in thickness, and it was confirmed that the ionic conductivity was also excellent. In addition, Comparative Example 1 is a polymer solid electrolyte prepared without using a non-volatile liquid compound, and was not prepared in the form of a free-standing film, and thus the thickness and ionic conductivity could not be measured.

In addition, Comparative Example 2 is a polymer solid electrolyte prepared using a PET release film instead of an SS foil as a base material without using a non-volatile liquid compound, and was prepared in the form of a free-standing film, but the uniformity is not good due to large thickness variation , It was confirmed that the ionic conductivity was also relatively lowered compared to Examples 1 to 3. In general, compared to metal foils such as SS, Cu, or Al, in the case of a PET release film, the adhesive strength with the electrolyte membrane made on the metal foil is low, and it is relatively easy to separate the electrolyte membrane after drying, but the strength of the electrolyte membrane If it is weak, it may be deformed by tearing or stretching, which may eventually make it difficult to use.

On the other hand, in Comparative Example 3, PEG-POSS, a non-volatile liquid compound, was used excessively compared to PPC, a polymer, so that it was not prepared in the form of a film and existed in a liquid state. Accordingly, thickness, uniformity and ionic conductivity could not be measured.

In Comparative Example 4, too little PEG-POSS, a non-volatile liquid compound, was used compared to the polymer, PPC, so that phase separation between the polymer and the non-volatile liquid compound did not occur, and the polymer and the non-volatile liquid compound were mixed. It was confirmed that a film containing the film was formed, and the uniformity was not good due to the large thickness variation.

From these results, when a polymer solid electrolyte is prepared by using a polymer having poor miscibility and a non-volatile liquid compound in an appropriate weight ratio and using phase separation between the polymer and the non-volatile liquid compound, the polymer and the non-volatile liquid compound A polymer solid electrolyte in the form of a free-standing film including a liquid membrane formed by phase separation and a polymer solid electrolyte membrane was prepared, and it was confirmed that the uniformity and ionic conductivity were excellent.

Although the present invention has been described above with limited examples and drawings, the present invention is not limited thereto, and is described below with the technical spirit of the present invention by those skilled in the art to which the present invention belongs. Of course, various modifications and variations are possible within the scope of equivalents of the claims to be made.

1: polymer solid electrolyte
10: registration
20: liquid film
30: polymer solid electrolyte membrane

Claims (20)

(S1) preparing a solution for forming a polymer solid electrolyte by adding a polymer, a non-volatile liquid compound, and a lithium salt to a solvent;
(S2) forming a coating layer by applying the polymer solid electrolyte forming solution on a substrate;
(S3) drying the coating layer to phase-separate the liquid membrane and the polymer solid electrolyte membrane; and
(S4) separating the polymer solid electrolyte membrane; a method of manufacturing a polymer solid electrolyte comprising a. According to claim 1,
The liquid membrane includes the non-volatile liquid compound, and the polymer solid electrolyte membrane includes the polymer and a lithium salt,
The non-volatile liquid compound is immiscible with the polymer,
The method of manufacturing a polymer solid electrolyte, wherein the liquid film is formed on a substrate, and the polymer solid electrolyte film is formed on the liquid film. According to claim 1,
The weight ratio of the polymer and the non-volatile liquid compound in the solution is 1:0.8 to 1:5.5, a method for producing a polymer solid electrolyte. According to claim 1,
The polymer is a polymer solid electrolyte comprising at least one selected from the group consisting of polypropylene carbonate (PPC), polyacrylonitrile (PAN) and polyvinylpyrrolidone (PVP). Manufacturing method of. According to claim 1,
The method of manufacturing a polymer solid electrolyte, wherein the non-volatile liquid compound includes at least one selected from the group consisting of polyhedral oligomeric silsesquioxane (POSS) and ionic liquid. According to claim 5,
The POSS includes one or more functional groups (functional groups, R), and the functional groups are functional groups containing one or more elements selected from O, N, S, Si, and P, or may bind to lithium ions. A method for producing a polymer solid electrolyte, which is a functional group with According to claim 6,
The functional group is polyethylene glycol (poly(ethylene glycol), PEG), alcohol (alcohol), amine (amine), carboxylic acid (carboxylic acid), allyl (allyl), epoxide (epoxide), thiol (thiol), silane (silane) ) or silanol (silanol), a method for producing a polymer solid electrolyte. According to claim 5,
The ionic liquid includes a cation and an anion, and the cation is imidazolium, pyrazolium, triazolium, thiazolium, oxazolium, pyridazinium, pyrid, substituted or unsubstituted by an alkyl group having 1 to 15 carbon atoms. At least one selected from the group consisting of midinium, pyrazinium, ammonium, phosphonium, pyridinium and pyrrolidinium,
The anion is PF ₆ ^- , BF ₄ ^- , CF ₃ SO ₃ ^- , N(CF ₃ SO ₂ ) ₂ ^- , N(C ₂ F ₅ SO ₂ ) ₂ ^- , C(CF ₂ SO ₂ ) ₃ ^- , AsF ₆ ^- , SbF ₆ ^- , AlCl ₄ ^- , NbF ₆ ^- , HSO ₄ ^- , ClO ₄ ^- , CH ₃ SO ₃ ^- and CF ₃ CO ₂ ^- containing at least one selected from the group consisting of, a polymeric solid Electrolyte manufacturing method. According to claim 1,
The lithium salt is LiTFSI (Lithium bis(trifluoromethanesulphonyl)imide), LiFSI (Lithium bis(fluorosulfonyl)imide), LiNO ₃ , LiOH, LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAsF ₆ , LiSbF ₆ , LiAlCl ₄ , CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, LiSCN, LiC(CF ₃ SO ₂ ) ₃ , (CF ₃ SO ₂ ) ₂ NLi and (FSO ₂ ) ₂ A method for producing a solid polymer electrolyte comprising at least one selected from the group consisting of NLi. According to claim 1,
The substrate is stainless steel. A method for producing a polymer solid electrolyte comprising at least one selected from the group consisting of Cu foil and Al foil. According to claim 1,
The method of forming the coating layer is bar coating, roll coating, spin coating, slit coating, die coating, blade coating, comma Coating (comma coating), slot die coating (slot die coating), lip coating (lip coating) or solution casting (solution casting), a method for producing a polymer solid electrolyte. According to claim 1,
The weight ratio of the polymer and the lithium salt is 1: 0.5 to 1: 3, a method for producing a polymer solid electrolyte. According to claim 1,
The solvent is propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propionate (MP), Dimethyl sulfoxide, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), vinylene carbonate (VC), gamma butyrolactone (GBL) , fluoroethylene carbonate (FEC), methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, pentyl acetate, methyl propionate, ethyl propionate, including at least one selected from the group consisting of ethyl propionate and butyl propionate To do, a method for producing a polymer solid electrolyte. According to claim 1,
Drying of the coating layer is a method for producing a polymer solid electrolyte, which is performed at 150 ° C or less. A polymer solid electrolyte containing a polymer and a lithium salt. According to claim 15,
The polymer solid electrolyte will have a thickness of 23 μm to 35 μm. According to claim 15,
The thickness deviation of the polymer solid electrolyte is 0.7 μm or less, and the thickness deviation is determined by measuring the thickness at 9 locations in a 3 x 3 cm 2 punched polymer solid electrolyte sample, and the deviation between the thickest and thinnest thickness The calculated polymer solid electrolyte. According to claim 15,
The polymer solid electrolyte is in the form of a freestanding film (freestanding film), the polymer solid electrolyte. According to claim 15,
The polymer solid electrolyte has an ionic conductivity of 1.2 x 10 ^-5 to 4.5 x 10 ^-5 S/cm, and the ionic conductivity is measured at 80 °C. An all-solid-state battery comprising the polymer solid electrolyte of claim 15.

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