Polymer-oxide composite bilayer-based solid electrolyte membrane, and manufacturing method therefor

Abstract

The present invention relates to a polymer-oxide composite bilayer-based solid electrolyte membrane and a manufacturing method therefor, the polymer-oxide composite bilayer-based solid electrolyte membrane comprising: a polymer-oxide composite solid electrolyte layer including a polymer solid electrolyte and Zr-doped lithium aluminum titanium phosphate (LAZTP); and a polymer solid electrolyte layer formed on the polymer-oxide composite solid electrolyte layer and including the polymer solid electrolyte.

Description

Polymer-oxide composite double layer-based solid electrolyte membrane and method for manufacturing the same

[0001] The present invention relates to a polymer-oxide composite double-layer-based solid electrolyte membrane and a method for manufacturing the same. More specifically, the invention relates to a polymer-oxide composite double-layer-based solid electrolyte membrane and a method for manufacturing the same, which can simultaneously improve lithium ion ionic conductivity, electrochemical oxidation stability, mechanical strength, and interfacial stability by composites a polymer solid electrolyte and a Zr element-doped oxide solid electrolyte, and by forming a double layer of the composite layer and the polymer solid electrolyte.

[0002] Lithium-ion batteries (LIBs) require improvement due to the high risk of fire and explosion caused by the use of liquid electrolytes containing organic solvents with low flash points. All-solid-state batteries (ASSBs), capable of meeting high safety standards, refer to batteries where all materials are solid, utilizing a solid electrolyte (SE) instead of a liquid electrolyte and separator; active research is currently being conducted on solid electrolytes. Additionally, using lithium metal as the anode offers the advantage of further increasing energy density.

[0003] Many studies are being conducted on polymer-based solid electrolytes using Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), which has high flexibility and stability against lithium metal.

[0004] Oxide-based solid electrolytes are Li of the sodium superion conductor (NASICON) series. 1+x Al x Ti 2-xMany materials based on (PO4)3(LATP) have been studied. By replacing sodium ions with lithium ions in sodium-based materials, they possess high ionic conductivity, electrochemical stability, and low electronic conductivity. Additionally, they do not react with moisture in the atmosphere and have high chemical stability, making them useful in research.

[0005] As such, while polymer-based and oxide-based solid electrolytes each possess their own advantages, polymer-based solid electrolytes suffer from issues of low ionic conductivity and mechanical strength, whereas oxide-based solid electrolytes exhibit poor contact with the electrodes, leading to increased interfacial resistance; consequently, using them as single solid electrolytes results in very low electrochemical performance. Furthermore, because the required characteristics differ for the anode and cathode, it is difficult to satisfy all these requirements using a single-layer composite solid electrolyte.

[0006] To overcome this, research is being conducted on elemental doping of oxide solid electrolytes and hybrid solid electrolytes (HSE) formed by mixing polymers and oxides. Depending on the ratio of polymer to oxide, these can be classified into ceramic-in-polymer (CIP), intermediates, and polymer-in-ceramic (PIC). In the case of CIP, mechanical strength is low, and in the case of PIC, interfacial resistance is high, making it difficult to satisfy all the required characteristics for the anode and cathode, and for each electrode, using only a single hybrid solid electrolyte. Additionally, when lithium metal is used as the cathode, the problem of deteriorating electrochemical performance caused by the growth of tree-branch-shaped dendrites on the surface must be resolved.

[0007] [Prior Art Literature]

[0008] [Patent Literature]

[0009] (Patent Document 1) Korean Published Patent KR 10-2020-0086081

[0010] (Patent Document 2) Korean Published Patent KR 10-2020-0050628

[0011] The present invention aims to solve the problems of the aforementioned conventional technology by combining a polymer solid electrolyte and a Zr element-doped oxide solid electrolyte, and by forming a double layer of the composite layer and the polymer solid electrolyte, thereby simultaneously improving the ionic conductivity of lithium ions, electrochemical oxidation stability, mechanical strength, and interfacial stability.

[0012] To achieve the aforementioned technical objectives, the present invention discloses a polymer-oxide composite double-layer based solid electrolyte membrane comprising: a polymer-oxide composite solid electrolyte layer comprising a polymer solid electrolyte and Zr-doped lithium aluminum titanium phosphate (LAZTP); and a polymer solid electrolyte layer formed on the polymer-oxide composite solid electrolyte layer and comprising the polymer solid electrolyte.

[0013] Here, the polymer solid electrolyte may include one or more selected from the group consisting of PAN (polyacrylonitrile), PVA (polyvinyl alcohol), PMMA (polymethylmethacrylate), PVP (polyvinylpyrrolidone), PEO (polyethylene oxide), PVdF (polyvinylidene fluoride), HFP (hexafluoropropylene) and PVC (polyvinyl chloride).

[0014] Here, the LAZTP may be included in an amount of 40 to 60 parts by weight per 100 parts by weight of the polymer-oxide composite solid electrolyte layer.

[0015] Here, based on 1 mol of LAZTP, the Zr may be included in an amount of 0.035 to 0.090 mol.

[0016] Here, the lattice spacing of the LAZTP may be 0.363 to 0.368 μm.

[0017] Here, the ionic conductivity of the solid electrolyte membrane is 4.6 x 10⁻⁶ -4 Up to 7.0 x 10 -4 Scm -1 It could be.

[0018] Here, the surface roughness of the solid electrolyte membrane may be 0.900 μm or less.

[0019] Here, the thickness of the solid electrolyte film may be 113 to 122 μm.

[0020] Here, the size of the nucleus of the polymer solid electrolyte formed on the polymer-oxide composite solid electrolyte layer may be 5 to 15 μm.

[0021] Here, the electrical resistance of the solid electrolyte membrane may be 8 to 15 Ω.

[0022] Here, the thickness ratio of the polymer-oxide composite solid electrolyte layer and the polymer solid electrolyte layer may be 7:3 to 7:6.

[0023] Meanwhile, in order to achieve the aforementioned technical problem, the present invention further discloses a method for manufacturing a polymer-oxide composite double layer-based solid electrolyte membrane, comprising: (a) forming a polymer-oxide composite solid electrolyte layer comprising a polymer solid electrolyte and Zr-doped lithium aluminum titanium phosphate (LAZTP); and (b) forming a polymer solid electrolyte layer comprising the polymer solid electrolyte on the polymer-oxide composite solid electrolyte layer.

[0024] Herein, prior to step (a), the method may include: a step of forming a mixed solution by mixing a Li precursor, an Al precursor, a Ti precursor solution, a Zr precursor solution, and a chelating agent; a step of adjusting the pH of the mixed solution to 4 to 6; a step of forming a sol by adding a phosphate precursor and an organic dispersant to the pH-adjusted mixed solution; a step of forming a gel by performing a first heat treatment of the sol; a step of forming a LAZTP precursor by performing a second heat treatment of the gel; and a step of forming the LAZTP by performing a third heat treatment of the LAZTP precursor.

[0025] Here, the chelating agent may include one or more selected from the group consisting of edetic acid, citric acid, metaphosphoric acid, pyrophosphoric acid, polyphosphoric acid, malic acid, tartaric acid, and phytic acid.

[0026] Here, the organic dispersant may include one or more selected from the group consisting of ethylene oxide, ethylene glycol, glycol distearate, glycol monostearate, glycol polymerate, glycol ethers, alcohols including alkylamines, polymerate ethers, compounds including sorbitol, nonionic surfactants, vinyl pyrrolidone, cellulose, and ethoxylates.

[0027] Here, the first heat treatment can be performed at 70 to 100 ℃ for 45 to 55 hours.

[0028] Here, the second heat treatment can be performed at 220 to 280 ℃ for 3 to 7 hours.

[0029] Here, the third heat treatment can be performed at 800 to 900 ℃ for 3 to 7 hours.

[0030] Here, the above step (a) may include: a step of mixing a polymer solid electrolyte precursor, a lithium precursor, and an organic solvent to form a polymer solid electrolyte solution; a step of adding the LAZTP to the polymer solid electrolyte solution and stirring to form a polymer-oxide solid electrolyte solution; and a step of applying the polymer-oxide solid electrolyte solution onto a substrate.

[0031] Here, the stirring can be performed for 10 to 14 hours.

[0032] The disclosed technology may have the following effects. However, this does not mean that a specific embodiment must include all of the following effects or only the following effects; therefore, the scope of the rights of the disclosed technology should not be understood as being limited by this.

[0033] According to the present invention, by combining a polymer solid electrolyte and a Zr element-doped oxide solid electrolyte, and forming a double layer of the composite layer and the polymer solid electrolyte, the ionic conductivity of lithium ions, electrochemical oxidation stability, mechanical strength, and interfacial stability can be simultaneously improved.

[0034] FIG. 1 is a schematic diagram illustrating the structure of a composite double-layer-based solid electrolyte membrane according to one embodiment of the present invention.

[0035] FIG. 2 is a flowchart illustrating a method for manufacturing a composite double-layer-based solid electrolyte membrane according to one embodiment of the present invention.

[0036] FIG. 3 is a schematic diagram illustrating the synthesis process of LAZTP according to one embodiment of the present invention.

[0037] FIG. 4 is a schematic diagram illustrating the manufacturing process of a composite double-layer-based solid electrolyte membrane according to one embodiment of the present invention.

[0038] Figure 5 is a structural analysis XRD spectrum and lattice analysis graph of LAZTP according to one embodiment of the present invention.

[0039] Figure 6 is an SEM / EDS image of LAZTP according to one embodiment of the present invention.

[0040] Figure 7 is an HRTEM image of LAZTP according to one embodiment of the present invention.

[0041] Figure 8 is a P 2s-Zr 3d XPS spectrum of LAZTP according to one embodiment of the present invention.

[0042] Figure 9 is a Nyquist plot of LAZTP HSE at 25°C according to one embodiment of the present invention.

[0043] FIG. 10 is an XRD spectrum and TGA graph of a composite double-layer-based solid electrolyte membrane according to one embodiment of the present invention.

[0044] Figure 11 is an SEM and AFM image of LAZTP 50% HSE according to one embodiment of the present invention.

[0045] FIG. 12 is an SEM and AFM image of a composite double-layer-based solid electrolyte membrane according to one embodiment of the present invention.

[0046] FIG. 13 is a Nyquist and Arrhenius plot of a composite double-layer-based solid electrolyte membrane according to one embodiment of the present invention.

[0047] FIG. 14 is a graph showing the LSV analysis results of a composite double-layer-based solid electrolyte membrane according to one embodiment of the present invention.

[0048] FIG. 15 is a graph showing the results of a DC polarization analysis of a composite double-layer-based solid electrolyte membrane according to one embodiment of the present invention.

[0049] FIG. 16 is an image and graph showing the results of the interfacial stability evaluation of a composite double-layer-based solid electrolyte membrane according to one embodiment of the present invention.

[0050] FIG. 17 is an image and graph showing the evaluation results of an all-solid-state battery based on a composite double-layer solid electrolyte membrane according to one embodiment of the present invention.

[0051] FIG. 18 is a graph showing the results of the evaluation of electrochemical stability and interfacial stability according to the interfacial contact direction of a composite double-layer-based solid electrolyte membrane according to one embodiment of the present invention.

[0052] The present invention is capable of various modifications and may have various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the invention to specific embodiments, and it should be understood that the invention includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0053] Similar reference numerals are used for similar components when describing each drawing. Terms such as "first," "second," etc., may be used to describe various components, but said components should not be limited by said terms. These terms are used solely for the purpose of distinguishing one component from another.

[0054] For example, without departing from the scope of the present invention, the first component may be named the second component, and similarly, the second component may be named the first component. The term "and / or" includes a combination of a plurality of related described items or any of a plurality of related described items.

[0055] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which this invention pertains.

[0056] Terms such as those defined in commonly used dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.

[0057] Throughout this specification, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0058] As used herein, terms of degree such as “about,” “substantially,” etc., are used to mean at or near the stated value when inherent manufacturing and material tolerances are presented in the stated meaning, and are used to prevent unscrupulous infringers from unfairly exploiting the disclosure in which precise or absolute values ​​are mentioned to aid in understanding the invention. Furthermore, throughout this specification, “a step of” or “a step of” does not mean “a step for”.

[0059] Throughout this specification, the term “combination thereof” included in the Markush-type expression means one or more mixtures or combinations selected from the group consisting of the components described in the Markush-type expression, and means including one or more selected from the group consisting of said components.

[0060]

[0061] Polymer-oxide composite double-layer based solid electrolyte membrane

[0062] The present specification discloses a polymer-oxide composite double-layer based solid electrolyte membrane comprising: a polymer-oxide composite solid electrolyte layer comprising a polymer solid electrolyte and Zr-doped lithium aluminum titanium phosphate (LAZTP); and a polymer solid electrolyte layer formed on the polymer-oxide composite solid electrolyte layer and comprising the polymer solid electrolyte.

[0063] FIG. 1 is a schematic diagram illustrating the structure of a composite double-layer-based solid electrolyte membrane according to one embodiment of the present invention.

[0064] Referring to FIG. 1, it can be seen that a composite double-layer based solid electrolyte membrane according to one embodiment of the present invention comprises: a polymer-oxide composite solid electrolyte layer comprising a polymer solid electrolyte and Zr-doped lithium aluminum titanium phosphate (LAZTP); and a polymer solid electrolyte layer formed on the polymer-oxide composite solid electrolyte layer and comprising the polymer solid electrolyte.

[0065] The above polymer solid electrolyte plays a key role in providing flexibility and interfacial stability with the lithium metal anode in a polymer-oxide composite double-layer-based solid electrolyte membrane. In particular, the polymer solid electrolyte layer can simultaneously improve the safety and performance of the all-solid-state battery by suppressing dendrite growth that may occur on the lithium metal surface and ensuring excellent interfacial contact with the electrode.

[0066] The above polymer solid electrolyte may include one or more selected from the group consisting of PAN (polyacrylonitrile), PVA (polyvinyl alcohol), PMMA (polymethylmethacrylate), PVP (polyvinylpyrrolidone), PEO (polyethylene oxide), PVdF (polyvinylidene fluoride), HFP (hexafluoropropylene), and PVC (polyvinyl chloride), but is not limited thereto. Preferably, PVDF-HFP (Poly(vinylidene fluoride-co-hexafluoropropylene)) may be used because it has high electrochemical stability and excellent stability against lithium metal.

[0067] With respect to 100 parts by weight of the polymer-oxide composite solid electrolyte layer, it is preferable that the LAZTP be included in an amount of 40 to 60 parts by weight, more preferable that it be included in an amount of 45 to 55 parts by weight, and most preferable that it be included in an amount of 48 to 52 parts by weight. For example, if the LAZTP is included in an amount of less than 40 parts by weight, the effect of improving ion conductivity within the polymer matrix is ​​insufficient, and a problem may arise in which the overall ion conductivity decreases. In addition, the resistance at the interface with the electrode may increase due to insufficient mechanical strength. Conversely, if the LAZTP is included in an amount exceeding 60 parts by weight, the interfacial interaction between the polymer and the oxide decreases, which lowers the homogeneity of the composite, and a problem may arise in which the flexibility of the membrane is significantly reduced due to the excessive oxide content.

[0068] Based on 1 mol of the above LAZTP, it is preferable that the above Zr be included in an amount of 0.035 to 0.090 mol, more preferable that it be included in an amount of 0.050 to 0.080 mol, and most preferable that it be included in an amount of 0.070 to 0.078 mol. For example, if the above Zr is included in an amount less than 0.035 mol, the effect of increasing the lattice spacing is negligible, so a problem may arise in which the improvement in ionic conductivity is insufficient. Conversely, if the above Zr is included in an amount exceeding 0.090 mol, the stability of the crystal structure may be lowered due to an excessive increase in lattice spacing, which may result in a problem in which the ionic conductivity decreases.

[0069] Zr doping involves Zr having a larger ionic radius at the Ti site. 4+ By introducing (0.72 Å), Ti 4+ By partially substituting (0.60 Å), the lattice spacing is increased, thereby expanding the pathways for the movement of lithium ions. This enhances the diffusion rate of lithium ions, which can significantly improve ion conductivity.

[0070] The lattice spacing of the above LAZTP is preferably 0.363 to 0.368 nm, more preferably 0.364 to 0.367 nm, and most preferably 0.365 to 0.366 nm. For example, if the lattice spacing is less than 0.363 nm, the ion conductivity may be significantly reduced due to insufficient pathways for lithium ion movement. Conversely, if the lattice spacing exceeds 0.368 nm, the stability of the crystal structure may be reduced due to excessive lattice expansion, which may lead to a deterioration in electrochemical performance.

[0071] The ionic conductivity of the above solid electrolyte membrane is 4.6 x 10⁻⁶ -4 Up to 7.0 x 10 -4 Scm -1 It is desirable that it is 5.0 × 10 -4 Up to 6.5 × 10 -4Scm -1 It is more desirable that it is 5.5 × 10 -4 Up to 6.0 × 10 -4 Scm -1 It is most desirable that the above ionic conductivity is 4.6 × 10 -4 Scm -1 If it is less than, the mobility of lithium ions slows down, which may cause a problem where the battery's output characteristics are significantly degraded. Conversely, the above ion conductivity is 7.0 × 10 -4 Scm -1 If it exceeds [value], the electronic conductivity also increases, which may cause a problem of increased self-discharge of the battery.

[0072] Ionic conductivity is a factor directly related to the output characteristics of all-solid-state batteries, and high ionic conductivity plays a role in improving the charge and discharge efficiency of the battery by ensuring the smooth movement of lithium ions.

[0073] The surface roughness of the solid electrolyte membrane is preferably 0.900 μm or less, more preferably 0.850 μm or less, and most preferably 0.790 to 0.800 μm. Surface roughness is an important factor determining interfacial contact with the electrode, and low surface roughness forms a uniform interface to minimize interfacial resistance and improve battery performance. For example, if the surface roughness exceeds 0.900 μm, non-uniform contact occurs at the interface with the electrode, which may lead to performance degradation due to localized current concentration.

[0074] The thickness of the solid electrolyte membrane is preferably 113 to 122 μm, and more preferably 115 to 120 μm. For example, if the thickness of the solid electrolyte membrane is less than 113 μm, problems such as an increased risk of electrical short circuits or insufficient mechanical strength may occur. Conversely, if the thickness of the solid electrolyte membrane exceeds 122 μm, problems such as increased ion conduction resistance or decreased energy density may occur. At this time, the thickness of the polymer-oxide composite solid electrolyte layer is preferably 60 to 80 μm, and the thickness of the polymer solid electrolyte layer is preferably 40 to 60 μm. Within the thickness range, the polymer-oxide composite solid electrolyte layer and the polymer solid electrolyte layer can achieve performance enhancement through the composite formation of polymers and oxides and the formation of double layers.

[0075] The size of the nuclei of the polymer solid electrolyte formed on the polymer-oxide composite solid electrolyte layer is preferably 5 to 15 μm, more preferably 6 to 12 μm, and most preferably 7 to 9 μm. The size of the polymer solid electrolyte nuclei is an important factor in determining the microstructure and surface characteristics of the polymer solid electrolyte layer, and an appropriate nucleus size plays a role in ensuring uniform surface formation and excellent interfacial contact. For example, if the size of the nuclei is less than 5 μm, the homogeneity of the surface is reduced due to the excessively small nuclei, which may cause a problem of increased interfacial resistance. Conversely, if the size of the nuclei exceeds 15 μm, the surface roughness is increased due to the excessively large nuclei, which may cause a problem of reduced contact with the electrode.

[0076] The electrical resistance of the solid electrolyte membrane is preferably 8 to 15 Ω, more preferably 9 to 13 Ω, and most preferably 10 to 12 Ω. For example, if the electrical resistance is less than 8 Ω, the electron conductivity increases, which may lead to increased self-discharge of the battery and reduced safety. Conversely, if the electrical resistance exceeds 15 Ω, the output characteristics of the battery may be significantly degraded due to excessive internal resistance, which may result in reduced practicality.

[0077] The thickness ratio of the polymer-oxide composite solid electrolyte layer and the polymer solid electrolyte layer is preferably 7:3 to 7:6, and more preferably 7:4 to 7:6. For example, if the thickness ratio is less than 7:3, the polymer-oxide composite solid electrolyte layer becomes excessively thick, and the thickness of the polymer solid electrolyte layer is relatively insufficient, which may cause a problem of reduced interfacial stability with lithium metal. Conversely, if the thickness ratio exceeds 7:6, the polymer solid electrolyte layer becomes excessively thick, which may cause a problem of reduced battery performance due to decreased overall ion conductivity.

[0078] The present specification further discloses an all-solid-state battery comprising the above-mentioned composite solid electrolyte membrane.

[0079] The above-described all-solid-state battery is preferably formed in the order of a positive electrode, a polymer-oxide composite solid electrolyte layer, a polymer solid electrolyte layer, and a lithium metal negative electrode. If the lithium metal negative electrode and the polymer-oxide composite solid electrolyte layer of the present invention are formed to be in interfacial contact, a side reaction may occur between the LAZTP and the lithium metal, which may result in a decrease in electrochemical stability and interfacial stability.

[0080]

[0081] <Method for manufacturing a polymer-oxide composite double layer-based solid electrolyte membrane>

[0082] Meanwhile, the present specification discloses a method for manufacturing a polymer-oxide composite double-layer-based solid electrolyte membrane, comprising: (a) forming a polymer-oxide composite solid electrolyte layer comprising a polymer solid electrolyte and Zr-doped lithium aluminum titanium phosphate (LAZTP); and (b) forming a polymer solid electrolyte layer comprising the polymer solid electrolyte on the polymer-oxide composite solid electrolyte layer.

[0083] FIG. 2 is a flowchart illustrating a method for manufacturing a composite double-layer-based solid electrolyte membrane according to one embodiment of the present invention.

[0084] Referring to FIG. 2, it can be seen that a method for manufacturing a composite double-layer-based solid electrolyte membrane according to one embodiment of the present invention comprises: (a) forming a polymer-oxide composite solid electrolyte layer comprising a polymer solid electrolyte and Zr-doped lithium aluminum titanium phosphate (LAZTP); and (b) forming a polymer solid electrolyte layer comprising the polymer solid electrolyte on the polymer-oxide composite solid electrolyte layer.

[0085] FIG. 3 is a schematic diagram illustrating the manufacturing process of a composite double-layer-based solid electrolyte membrane according to one embodiment of the present invention.

[0086] FIG. 4 is a schematic diagram illustrating the manufacturing process of a composite double-layer-based solid electrolyte membrane according to one embodiment of the present invention.

[0087] Referring to FIGS. 3 and 4, it can be seen that the manufacturing process of a composite double-layer-based solid electrolyte membrane according to one embodiment of the present invention largely consists of a process of synthesizing LAZTP by the sol-gel method and a process of forming each layer by casting solid electrolyte solutions.

[0088] Prior to step (a) above, the method may include: a step of forming a mixed solution by mixing a Li precursor, an Al precursor, a Ti precursor solution, a Zr precursor solution, and a chelating agent; a step of adjusting the pH of the mixed solution to 4 to 6; a step of forming a sol by adding a phosphate precursor and an organic dispersant to the pH-adjusted mixed solution; a step of forming a gel by heat-treating the sol first; a step of forming a LAZTP precursor by heat-treating the gel secondarily; and a step of forming the LAZTP by heat-treating the LAZTP precursor thirdly.

[0089] The above chelating agent may include one or more selected from the group consisting of edetic acid, citric acid, metaphosphoric acid, pyrophosphoric acid, polyphosphoric acid, malic acid, tartaric acid, and phytic acid, but is not limited thereto. The chelating agent plays a role in enabling the synthesis of a uniform precursor by forming a stable complex with a metal cation. Preferably, citric acid may be used, as it can form stable chelate bonds with various metal ions.

[0090] The above organic dispersant may include one or more selected from the group consisting of ethylene oxide, ethylene glycol, glycol distearate, glycol monostearate, glycol polymerate, glycol ethers, alcohols including alkylamines, polymerate ethers, compounds including sorbitol, nonionic surfactants, vinyl pyrrolidone, cellulose, and ethoxylates. The organic dispersant performs the role of promoting the formation of a uniform sol and preventing particle aggregation through a polyesteration reaction with citric acid.

[0091] The above first heat treatment is preferably performed at 70 to 100 ℃ for 45 to 55 hours, more preferably at 80 to 90 ℃ for 47 to 50 hours, and most preferably at 85 ℃ for 48 hours. For example, if the above first heat treatment temperature is below 70 ℃, the gelation reaction may not proceed sufficiently, and a problem may occur in which a non-uniform precursor is formed. Conversely, if the above first heat treatment temperature exceeds 100 ℃, a problem may occur in which homogeneity is reduced due to rapid solvent evaporation.

[0092] The above secondary heat treatment is preferably performed at 220 to 280 ℃ for 3 to 7 hours, more preferably at 240 to 260 ℃ for 4 to 6 hours, and most preferably at 250 ℃ for 5 hours. For example, if the secondary heat treatment temperature is below 220 ℃, the removal of the chelating agent and the dispersing agent is incomplete, and a problem may arise in which impurities remain. Conversely, if the secondary heat treatment temperature exceeds 280 ℃, a problem may arise in which the homogeneity of the precursor is reduced due to rapid decomposition.

[0093] The above third heat treatment is preferably performed at 800 to 900 ℃ for 3 to 7 hours, more preferably at 830 to 870 ℃ for 4 to 6 hours, and most preferably at 850 ℃ for 5 hours. For example, if the temperature of the third heat treatment is less than 800 ℃, crystallization may not proceed sufficiently, resulting in the presence of an amorphous phase and a decrease in ion conductivity. Conversely, if the temperature of the third heat treatment exceeds 900 ℃, excessive sintering may cause the particle size to increase excessively, leading to a decrease in dispersibility within the composite.

[0094] The above step (a) may include: a step of forming a polymer solid electrolyte solution by mixing a polymer solid electrolyte precursor, a lithium precursor, and an organic solvent; a step of forming a polymer-oxide solid electrolyte solution by adding the LAZTP to the polymer solid electrolyte solution and stirring; and a step of applying the polymer-oxide solid electrolyte solution onto a substrate.

[0095] The stirring is preferably performed for 10 to 14 hours, more preferably for 11 to 13 hours, and most preferably for 12 hours. For example, if the stirring time is less than 10 hours, the dispersion of LAZTP particles may be insufficient, leading to the formation of a non-uniform composite. Conversely, if the stirring time exceeds 14 hours, excessive stirring may cause the degradation of polymer chains, resulting in reduced performance. The stirring process serves to optimize the performance of the composite solid electrolyte by ensuring that LAZTP particles are uniformly dispersed within the polymer matrix. Through sufficient stirring, interfacial interactions between the oxide and the polymer are maximized, which can simultaneously improve ionic conductivity and mechanical properties.

[0096] {Examples and Evaluation}

[0097] The present invention is to be explained in more detail through the following examples, but the following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0098] <Example>

[0099] Example 1

[0100] 1. Synthesis of Zr-Doped Lithium Aluminum Titanium Phosphate (LAZTP)

[0101] A solvent was prepared by mixing distilled water and nitric acid in a volume ratio of 3:1, and a titanium butoxide (Ti(C4H9O)4) solution was added and stirred until it was completely dissolved and became transparent. Then, citric acid (C6H8O7), a chelating agent capable of forming metal ion complexes, was added in a molar ratio of 2:1 with the metal cation. Subsequently, lithium nitrate (LiNO3), aluminum nitrate nonahydrate (Al(NO3)3·9H2O), and zirconium nitrate (ZrO(NO3)3·xH2O) were added and dissolved. Since zirconium nitrate does not dissolve if other substances are present in the solution, a solution previously dissolved in 8 mL of distilled water was added to the above solution to adjust the volume ratio of the mixed solvent to distilled water:nitric acid to 4:1, and the solution was titrated with an ammonium solution (NH4OH) to reach pH 5. Subsequently, ammonium dihydrogen phosphate (NH4H2PO4) was dissolved, and ethylene glycol (C2H6O2), which acts as a dispersant to form a homogeneous sol through the polyesteration reaction between citric acid and ethylene glycol, was added in a molar ratio of 1:1 with citric acid. The gelation process was carried out at 85°C for 48 hours, and the formed gel was heat-treated in a furnace at 250°C for 5 hours at a heating rate of 5°C / min to form a black LAZTP precursor from which the chelating agent and dispersant were removed. This was then ground using a mortar and pestle, and heat-treated in a tube furnace at 850°C for 5 hours at a heating rate of 5°C / min to synthesize a white LAZTP powder containing 0.075 mol of Zr.

[0102]

[0103] 2. Synthesis of a Polymer-Oxide Composite Bilayer-Based Solid Electrolyte Membrane

[0104] PVDF-HFP pellets and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) were placed in N,N-dimethylacetamide (DMAc) solvent and stirred at 50 °C until the solution became clear. 60 wt% of LiTFSI was added relative to PVDF-HFP. Subsequently, 50 wt% of LAZTP powder was added to the solution and stirred for 12 hours. The solution containing 50 wt% LAZTP was cast onto a glass Petri dish and vacuum dried at 50 °C for 6 hours to form a membrane. Afterward, a solution without LAZTP was drop-casted onto it and vacuum dried further at 50 °C for 24 hours. The dried solid electrolyte membrane was cooled to room temperature, removed from the dish, and stored in a glove box. This composite double-layer-based solid electrolyte membrane was named LAZTP Dual HSE.

[0105] In addition, an all-solid-state battery was manufactured by applying the above-mentioned LAZTP Dual HSE in the order of a positive electrode, a polymer-oxide composite solid electrolyte layer, a polymer solid electrolyte layer, and a lithium metal anode.

[0106] As described above, a composite double-layer-based solid electrolyte membrane of the present invention and an all-solid-state battery including the same were manufactured (hereinafter referred to as “Example 1”).

[0107]

[0108] Comparative Example 1

[0109] A solid electrolyte membrane consisting of a single layer of a polymer solid electrolyte layer of PVDF-HFP (hereinafter referred to as “PVDF-HFP SPE”) and an all-solid-state battery including the same were manufactured (hereinafter referred to as “Comparative Example 1”).

[0110]

[0111] Comparative Example 2

[0112] A solid electrolyte membrane (LAZTP 50% HSE) composed of a single layer of a polymer-oxide composite solid electrolyte layer containing 0.075 mol of Zr and an all-solid-state battery containing the same were prepared (hereinafter referred to as “Comparative Example 2”).

[0113]

[0114] Comparative Example 3

[0115] A composite double-layer-based solid electrolyte membrane and an all-solid-state battery containing the same were manufactured in the same manner as in Example 1, except that they were stacked in the order of a positive electrode, a polymer solid electrolyte layer, a polymer-oxide composite solid electrolyte layer, and a lithium metal negative electrode (hereinafter referred to as “Comparative Example 3”).

[0116]

[0117] <Evaluation>

[0118] 1. Synthesis of LAZTP Oxide Solid Electrolyte and Evaluation of Zr Doping Optimization

[0119] Figure 5 is a structural analysis XRD spectrum and lattice analysis graph of LAZTP according to one embodiment of the present invention.

[0120] Specifically, Fig. 5a is the XRD pattern of the synthesized LAZTP, Fig. 5b is an enlarged XRD graph of LAZTP, and Fig. 5c is a graph of the LAZTP lattice constant and lattice volume.

[0121] Referring to Figures 5a and 5b, the XRD analysis results of LAZTP synthesized by the sol-gel method can be observed. All LAZTPs exhibited graphs similar to the LiTi2(PO4)3-based reference, confirming that they were synthesized without impurities. As the Zr content increased, the peak around (113) 24.54°, which corresponds to the main crystal peak, tended to shift to the left, and Zr 4+ The ionic radius of Ti is 0.72 Å. 4+ It was confirmed that the interplanar distance was expanded as the spacing between lattices increased because it was larger than the ionic radius of 0.60 Å.

[0122] Referring to Figure 5c, it can be seen that as the Zr doping content increases through the Rietveld refining method, the lattice constant and lattice volume tend to increase.

[0123] Figure 6 is an SEM / EDS image of LAZTP according to one embodiment of the present invention.

[0124] Figure 7 is an HRTEM image of LAZTP according to one embodiment of the present invention.

[0125] Referring to Figures 6 and 7, it can be seen in the SEM images that the particle sizes of LAZTP-0.075 and LATP are formed to be approximately 3 to 5 μm, and that all constituent elements are uniformly distributed. In addition, as a result of measuring the lattice spacing through HRTEM images, it was confirmed that it increased from 0.361 nm to 0.366 nm, which is consistent with the trend of the XRD graph.

[0126] Figure 8 is a P 2s-Zr 3d XPS spectrum of LAZTP according to one embodiment of the present invention.

[0127] Specifically, Fig. 8a is the P 2s-Zr 3d XPS spectrum of LAZTP-0.075, and Fig. 8b is the P 2s-Zr 3d XPS spectrum of LATP.

[0128] Referring to Figures 8a and 8b, when compared with the P 2s-Zr 3d XPS spectrum of LATP, Zr in the Zr 3d XPS spectrum of LAZTP-0.075 4+ By confirming the presence of, it can be confirmed that doping was successful.

[0129] Figure 9 is a Nyquist plot of LAZTP HSE at 25°C according to one embodiment of the present invention.

[0130] Referring to Fig. 9, the results of the EIS analysis for measuring the ionic conductivity of the composite solid electrolyte layer with 50% oxide content added to optimize the Zr doping content of LATP can be seen. The total resistance (Re) of LATP HSE, LAZTP-0.050 HSE, LAZTP-0.075 HSE, and LAZTP-0.100 HSE were found to be 20, 13.1, 8.4, and 13.3 Ω, respectively. The ionic conductivity was 3.5 × 10⁻⁶, respectively. -4 , 4.6 × 10 -4 , 7.2 × 10 -4 and 4.5 × 10 -4 Scm -1 The highest ionic conductivity was measured in LAZTP-0.075 HSE, and this ionic conductivity was calculated according to the following Equation 1:

[0131] [Mathematical Formula 1]

[0132] σ = L / (R e ×S)

[0133] Here, L corresponds to the thickness, and S corresponds to the contact area between the solid electrolyte layer and the electrode.

[0134] In other words, it was found that the introduction of Zr increased the lattice spacing, widening the Li transport pathway and improving ionic conductivity, whereas in the case of LAZTP-0.100 HSE, the result was interpreted as a decrease in ionic conductivity due to an excessive increase in lattice spacing. Accordingly, the doping content was optimized to LATP oxide doped with 0.075 mol of Zr, and LAZTP-0.075 HSE was subsequently named LAZTP 50% HSE.

[0135]

[0136] 2. Evaluation of Polymer-Oxide Composite Double Layer-Based Solid Electrolyte Membrane Synthesis

[0137] FIG. 10 is an XRD spectrum and TGA graph of a composite double-layer-based solid electrolyte membrane according to one embodiment of the present invention.

[0138] Specifically, FIG. 10a is an XRD pattern of a solid electrolyte membrane, FIG. 10b and FIG. 10c are a thermogravimetric graph of a solid electrolyte membrane and an enlarged graph thereof, and FIG. 10d is a tensile strength-strain graph of a solid electrolyte membrane.

[0139] Referring to Fig. 10a, the XRD analysis results of Comparative Example 1 (PVDF-HFP SPE) and Comparative Example 2 (LAZTP 50% HSE) for comparison with a composite double-layer-based solid electrolyte membrane fabricated using a Zr-doped LATP oxide and a PVDF-HFP polymer can be seen. At this time, it was confirmed that Example 1 and Comparative Examples 1 and 2 were all synthesized without impurities. In the case of Example 1, it was confirmed that the composite solid electrolyte form was formed by the appearance of crystal peaks of PVDF-HFP corresponding to the α(100), β(200 / 110), and α(002) phases and crystal plane peaks corresponding to LATP at 2θ = 18°, 20°, and 39°, respectively.

[0140] Referring to Figures 10b and 10c, the results of the thermal stability evaluation of the composite double-layer-based solid electrolyte membrane can be confirmed through TGA analysis. Specifically, mass loss due to moisture and residual solvent was observed in the range of 25 to 300 °C, decomposition of LiTFSI occurred at temperatures above 300 °C, decomposition of PVDF-HFP occurred at approximately 450 °C, and LAZTP remained without decomposition up to 900 °C. The decomposition temperature of LiTFSI was 320 °C for Comparative Example 1 (PVDF-HFP SPE), and 325 °C and 329 °C for Example 1 (LAZTP Dual HSE) and Comparative Example 2 (LAZTP 50% HSE), respectively, indicating that thermal stability improves due to interaction with lithium salts as the oxide content increases in the composite solid electrolyte layer with added LAZTP.

[0141] Referring to Fig. 10d, the results of UTM analysis performed to verify the mechanical properties of the composite double-layer-based solid electrolyte membrane can be seen. As a result of the analysis, the tensile strengths of Comparative Example 1 (PVDF-HFP HSE), Comparative Example 2 (LAZTP 50% HSE), and Example 1 (LAZTP Dual HSE) were 4.95, 4.46, and 6.32 MPa, respectively, and the strains were 186, 111, and 148%, respectively. This is a result of the LAZTP particles being uniformly dispersed within the polymer matrix in the double-layer form in Example 1, which effectively improved the mechanical strength. On the other hand, Comparative Example 2 (LAZTP 50% HSE) exhibited aggregation due to a high content of brittle oxides, and it was found that this aggregation weakened the mechanical strength.

[0142] Figure 11 is an SEM and AFM image of LAZTP 50% HSE according to one embodiment of the present invention.

[0143] Specifically, FIGS. 11a to 11c are cross-sectional SEM images, surface SEM images, and AFM images of LAZTP 50% HSE.

[0144] FIG. 12 is an SEM and AFM image of a composite double-layer-based solid electrolyte membrane according to one embodiment of the present invention.

[0145] Specifically, FIGS. 12a to 12c are cross-sectional SEM images, surface SEM images, and AFM images of LAZTP Dual HSE.

[0146] Referring to Figures 11 and 12, the layer structure and surface analysis results of Comparative Example 2 and Example 1 can be confirmed. First, through cross-sectional SEM images of the composite solid electrolyte layers, it can be confirmed that Comparative Example 2 (LAZTP 50% HSE) and Example 1 (LAZTP Dual HSE) are formed with thicknesses of 107 μm and 117 μm, respectively, and that Example 1 (LAZTP Dual HSE) forms a double layer structure. Additionally, through surface SEM, it can be confirmed that in Comparative Example 2 (LAZTP 50% HSE), LAZTP influences the nucleation of spherical PVDF-HFP, causing the size of the spherulites to increase to an average of 19 μm, whereas in Example 1 (LAZTP Dual HSE), a relatively small nucleus size of approximately 8 μm appears because no oxide is present on the surface. Furthermore, the results of comparing surface roughness (Ra) through AFM analysis can be confirmed. Comparative Example 2 (LAZTP 50% HSE) and Example 1 (LAZTP Dual HSE) were measured to have surface roughness of 0.947 and 0.792 μm, respectively. In this case, the lower the surface roughness, the more uniform the surface, which can improve interfacial contact with the electrode.

[0147]

[0148] 3. Electrochemical Performance Evaluation of Polymer-Oxide Composite Double Layer-Based Solid Electrolyte Membranes

[0149] FIG. 13 is a Nyquist and Arrhenius plot of a composite double-layer-based solid electrolyte membrane according to one embodiment of the present invention.

[0150] Specifically, FIG. 13a is a Nyquist plot of a solid electrolyte membrane measured at 25 °C, and FIG. 13b is an Arrhenius plot of the ionic conductivity of a solid electrolyte membrane calculated from 25 to 105 °C.

[0151] Referring to Fig. 13a, the results of temperature-dependent EIS analysis for calculating the ionic conductivity and activation energy (Ea) at 25 °C of a composite double-layer-based solid electrolyte membrane containing LAZTP-0.075 particles with optimized doping content can be seen. The total resistance (Re) of Comparative Example 1 (PVDF-HFP SPE), Comparative Example 2 (LAZTP 50% HSE), and Example 1 (LAZTP Dual HSE) were found to be 76, 8.4, and 11.8 Ω, respectively, and the ionic conductivity was 6.5 × 10⁻⁶, respectively. -5 , 7.2 × 10 -4 , 5.0 × 10 -4 Scm -1 As the LAZTP content increased, the ion conductivity tended to increase.

[0152] Referring to Fig. 13b, the Arrhenius plot based on temperature-dependent EIS analysis performed in the range of 25 to 105 °C and the activation energy (Ea) obtained therefrom can be seen. The activation energy (Ea) was calculated using the following Equation 2:

[0153] [Mathematical Formula 2]

[0154] σ = Ac (-Ea / kbT)

[0155] Here, A is the prior exponential factor, kb(8.617×10⁻⁵ eVK -1 ) represents the Boltzmann constant, and T (K) represents the absolute temperature.

[0156] As a result of calculation, the activation energies were 0.25, 0.17, and 0.19 eV, showing a tendency to decrease with increasing LAZTP content. In this case, the lower the activation energy, the faster the movement speed of lithium ions within the polymer matrix.

[0157] FIG. 14 is a graph showing the LSV analysis results of a composite double-layer-based solid electrolyte membrane according to one embodiment of the present invention.

[0158]

[0159] Specifically, FIG. 14a and FIG. 14b are curves showing the electrochemical oxidation stability of a solid electrolyte membrane measured at 25 and 55 °C, respectively, and

[0160] Referring to Figures 14a and 14b, the results of LSV analysis performed at 25 and 55 °C to evaluate electrochemical oxidation stability can be seen. At 25 °C, it did not decompose up to a voltage of 4.5 V in all cases, and a trend was observed where stability increased as the LAZTP content increased. At 55 °C as well, Example 1 (LAZTP Dual HSE) exhibited high electrochemical oxidation stability of approximately 4.5 V.

[0161] FIG. 15 is a graph showing the results of a DC polarization analysis of a composite double-layer-based solid electrolyte membrane according to one embodiment of the present invention.

[0162] Specifically, FIG. 15a and FIG. 15b are curves showing the electronic conductivity of a solid electrolyte membrane measured at 25 and 55 °C, respectively.

[0163] Referring to FIGS. 15a and 15b, the results of DC polarization analysis performed at 25 and 55 °C can be seen. At 25 °C, 0.2 × 10⁻⁶ in Comparative Example 1, Comparative Example 2, and Example 1, respectively -9 , 3.4 × 10 -9 , 1.1 × 10 -9 Scm -1 The electronic conductivity was measured, and even at 55 ℃, Example 1 (LAZTP Dual HSE) was 7 × 10 -9 Scm -1 It was confirmed that it exhibits low electronic conductivity.

[0164]

[0165] 4. Evaluation of Interfacial Stability and All-Solid State Battery Application of Polymer-Oxide Composite Bilayer-Based Solid Electrolyte Membranes

[0166] FIG. 16 is an image and graph showing the results of the interfacial stability evaluation of a composite double-layer-based solid electrolyte membrane according to one embodiment of the present invention.

[0167] Specifically, FIG. 16a is a schematic diagram of a cell assembly method for an interface stability test, FIG. 16b is a graph showing the limiting current density of a solid electrolyte membrane at 55°C, and FIG. 16c is a graph showing the interface stability of a solid electrolyte membrane at 55°C.

[0168] Referring to FIG. 16a, a schematic diagram of a cell prepared for evaluating the interfacial stability of the composite double-layer-based solid electrolyte membrane of the present invention can be seen.

[0169] Referring to Fig. 16b, the results of measuring the limiting current density while increasing the current density to analyze the interfacial stability between the solid electrolyte membrane and the lithium metal anode at 55 °C can be seen. Since LAZTP has a problem of reacting with lithium metal, to block this, the cell was assembled by overlapping two solid electrolyte membranes so that a layer without LAZTP on the surface and the lithium metal came into contact, as shown in Fig. 17a. As a result of the measurement, Comparative Example 2 (LAZTP 50% HSE) and Example 1 (LAZTP Dual HSE) showed values ​​of 0.7 and 0.8 mAcm, respectively. -2 It showed the limiting current density.

[0170] Referring to Fig. 16c, 0.2 mAcm -2 The results of the Li plating / stripping test conducted at a constant current density can be confirmed. In the case of Comparative Example 2 (LAZTP 50% HSE) and Example 1 (LAZTP Dual HSE), the initial polarization voltage was measured to be approximately 70 mV, but in Comparative Example 2 (LAZTP 50% HSE), side reactions and interfacial resistance gradually increased, and a short circuit occurred after 120 hours. On the other hand, Example 1 (LAZTP Dual HSE) did not experience a short circuit for 400 hours and exhibited stable interfacial performance with lithium metal through its double-layer structure.

[0171] FIG. 17 is an image and graph showing the evaluation results of an all-solid-state battery based on a composite double-layer solid electrolyte membrane according to one embodiment of the present invention.

[0172] Specifically, FIG. 17a is a schematic diagram of a cell assembly method for evaluating the performance of an all-solid-state battery, FIG. 17b is a graph showing rate capability characteristics at 55°C, and FIG. 17c is a graph showing cycle life stability under conditions of 55°C and 0.5°C.

[0173] Referring to FIG. 17a, a schematic diagram of a cell manufactured for the evaluation of an all-solid-state battery of the composite double-layer-based solid electrolyte membrane of the present invention can be seen.

[0174] Referring to FIGS. 17b and 17c, the results of fabricating an LFP cathode to apply a composite double-layer-based solid electrolyte membrane to an all-solid-state battery, as well as performing cell assembly and electrochemical performance evaluation at 55°C, can be confirmed. First, in the case of Comparative Example 1, battery failure occurred within 1 to 2 charge-discharge cycles due to the absence of an oxide solid electrolyte, high surface roughness, and low ionic conductivity, making charge-discharge analysis difficult. Accordingly, as a result of evaluating the rate capability characteristics for Example 1 and Comparative Example 2, the reversible capacities at 0.1, 0.2, 0.5, 1.0, and 2.0 C were measured as 163.6, 158.4, 149.3, 138.1, and 127.3 mAh / g for Comparative Example 2 (LAZTP 50% HSE), respectively, while those for Example 1 (LAZTP Dual HSE) were 165.0, 161.8, 158.7, 150.0, and 138.1 mAh / g, respectively. As the C-rate increased, Example 1 (LAZTP Dual HSE) showed a relatively higher reversible capacitance. When lifespan stability was evaluated at 0.5 C, Comparative Example 2 (LAZTP 50% HSE) experienced a short circuit after 58 cycles due to side reactions and high interfacial resistance, whereas Example 1 (LAZTP Dual HSE) demonstrated excellent performance by exhibiting stable charge / discharge performance with a high reversible capacity of about 160 mAh / g and a Coulomb efficiency of over 99% even after 70 cycles.

[0175] FIG. 18 is a graph showing the results of the evaluation of electrochemical stability and interfacial stability according to the interfacial contact direction of a composite double-layer-based solid electrolyte membrane according to one embodiment of the present invention.

[0176] Specifically, FIG. 18a is a graph showing the lithium plating / stripping ability and electrochemical reduction stability, FIG. 18b is a graph showing the solid electrolyte interface stability of a composite double-layer-based solid electrolyte film according to the type of solid electrolyte layer in contact with the lithium metal anode at 55 ℃, FIG. 18c is an XRD spectrum after the interface stability test, and FIG. 18d is an XPS Ti 2p comparison graph after the interface stability test.

[0177] Referring to FIGS. 18a to 18d, it can be seen that in the composite double-layer-based solid electrolyte membrane of the present invention, excellent interfacial stability is exhibited when the lithium metal anode is in contact with a polymer solid electrolyte layer and the anode is in contact with a polymer-oxide composite solid electrolyte layer (LAZTP). In order to evaluate the interfacial stability according to the electrode in contact with LAZTP, CV analysis was performed with different types of solid electrolyte layers in contact with the lithium metal anode. As a result, it was confirmed that when LAZTP is formed toward the lithium metal anode, there is a problem of LAZTP reacting with the lithium metal. Specifically, in Example 1 (LAZTP Dual HSE) in which LAZTP and lithium metal do not come into contact, only Li plating / stripping reactions occur near 0 V and no side reactions appear, whereas in Comparative Example 3, in which LAZTP and lithium metal come into contact, a reduction current appears at approximately 1.5 V and it was confirmed that side reactions of LAZTP occur. In addition, when the interfacial stability evaluation was conducted, in Comparative Example 3, the interfacial resistance increased due to side reactions, causing a significant rise in polarization voltage and a short circuit to occur after approximately 130 hours. Subsequently, when the cell was disassembled and XRD analysis was performed on the solid electrolyte membrane that underwent the interfacial stability test, it was confirmed that an additional peak corresponding to reduced LAZTP appeared. Furthermore, when the Ti 2p spectrum was examined via XPS analysis, an additional Ti 3+ peak resulting from the Ti reduction reaction was observed. Through this, it was confirmed that blocking contact between LAZTP and Li metal affects performance improvement.

[0178]

[0179] According to the present invention, by combining a polymer solid electrolyte and a Zr element-doped oxide solid electrolyte, and forming a double layer of the composite layer and the polymer solid electrolyte, the ionic conductivity of lithium ions, electrochemical oxidation stability, mechanical strength, and interfacial stability can be simultaneously improved.

[0180] The foregoing description of the present invention is for illustrative purposes only, and those skilled in the art will understand that other specific forms can be easily modified without altering the technical concept or essential features of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. For example, each component described as a single unit may be implemented in a distributed manner, and components described as distributed may likewise be implemented in a combined form.

[0181] The scope of the present invention is defined by the claims set forth below rather than by the detailed description above, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of the present invention.

Claims

1. A polymer-oxide composite solid electrolyte layer comprising a polymer solid electrolyte and Zr-doped lithium aluminum titanium phosphate (LAZTP); and A polymer solid electrolyte layer formed on the above polymer-oxide composite solid electrolyte layer and comprising the above polymer solid electrolyte; Polymer-oxide composite bilayer-based solid electrolyte membrane.

2. In Paragraph 1, The above polymer solid electrolyte comprises one or more selected from the group consisting of PAN (polyacrylonitrile), PVA (polyvinyl alcohol), PMMA (polymethylmethacrylate), PVP (polyvinylpyrrolidone), PEO (polyethylene oxide), PVdF (polyvinylidene fluoride), HFP (hexafluoropropylene), and PVC (polyvinyl chloride), forming a polymer-oxide composite double-layer based solid electrolyte membrane.

3. In Paragraph 1, A polymer-oxide composite double-layer based solid electrolyte membrane comprising 40 to 60 parts by weight of LAZTP per 100 parts by weight of the polymer-oxide composite solid electrolyte layer.

4. In Paragraph 1, A polymer-oxide composite double-layer-based solid electrolyte membrane containing 0.035 to 0.090 mol of Zr based on 1 mol of LAZTP.

5. In Paragraph 1, A polymer-oxide composite double-layer-based solid electrolyte membrane having a lattice spacing of 0.363 to 0.368 μm for the LAZTP.

6. In Paragraph 1, The ionic conductivity of the above solid electrolyte membrane is 4.6 x 10⁻⁶ -4 Up to 7.0 x 10 -4 Scm -1 Phosphorus, polymer-oxide composite bilayer-based solid electrolyte membrane.

7. In Paragraph 1, A polymer-oxide composite double-layer based solid electrolyte membrane having a surface roughness of 0.900 μm or less.

8. In Paragraph 1, A polymer-oxide composite double-layer based solid electrolyte membrane, wherein the thickness of the solid electrolyte membrane is 113 to 122 μm.

9. In Paragraph 1, A polymer-oxide composite double layer-based solid electrolyte membrane, wherein the size of the nuclei of the polymer solid electrolyte formed on the polymer-oxide composite solid electrolyte layer is 5 to 15 μm.

10. In Paragraph 1, A polymer-oxide composite double-layer based solid electrolyte membrane having an electrical resistance of 8 to 15 Ω.

11. In Paragraph 1, A polymer-oxide composite double-layer based solid electrolyte membrane, wherein the thickness ratio of the polymer-oxide composite solid electrolyte layer and the polymer solid electrolyte layer is 7:3 to 7:

6.

12. (a) forming a polymer-oxide composite solid electrolyte layer comprising a polymer solid electrolyte and Zr-doped lithium aluminum titanium phosphate (LAZTP); and (b) forming a polymer solid electrolyte layer comprising the polymer solid electrolyte on the polymer-oxide composite solid electrolyte layer; comprising, Method for manufacturing a solid electrolyte membrane based on a polymer-oxide composite double layer.

13. In Paragraph 12, Prior to the above (a) step, A step of forming a mixed solution by mixing a Li precursor, an Al precursor, a Ti precursor solution, a Zr precursor solution, and a chelating agent; A step of adjusting the pH of the above mixed solution to 4 to 6; A step of forming a sol by adding a phosphate precursor and an organic dispersant to the above pH-adjusted mixed solution; A step of forming a gel by performing a first heat treatment on the above sol; A step of forming a LAZTP precursor by performing a second heat treatment on the above gel; and A method for manufacturing a polymer-oxide composite double-layer-based solid electrolyte membrane, comprising the step of forming the LAZTP by heat-treating the LAZTP precursor a third time.

14. In Paragraph 13, A method for manufacturing a polymer-oxide composite double-layer-based solid electrolyte membrane, wherein the chelating agent comprises one or more selected from the group consisting of edetic acid, citric acid, metaphosphoric acid, pyrophosphoric acid, polyphosphoric acid, malic acid, tartaric acid, and phytic acid.

15. In Paragraph 13, A method for manufacturing a polymer-oxide composite double-layer based solid electrolyte membrane, wherein the above-mentioned organic dispersant comprises one or more selected from the group consisting of ethylene oxide, ethylene glycol, glycol distearate, glycol monostearate, glycol polymerate, glycol ethers, alcohols including alkylamines, polymerate ethers, compounds including sorbitol, nonionic surfactants, vinyl pyrrolidone, cellulose, and ethoxylates.

16. In Paragraph 13, A method for manufacturing a polymer-oxide composite double-layer-based solid electrolyte membrane, wherein the above first heat treatment is performed at 70 to 100 ℃ for 45 to 55 hours.

17. In Paragraph 13, A method for manufacturing a polymer-oxide composite double-layer-based solid electrolyte membrane, wherein the above secondary heat treatment is performed at 220 to 280 ℃ for 3 to 7 hours.

18. In Paragraph 13, A method for manufacturing a polymer-oxide composite double-layer-based solid electrolyte membrane, wherein the above third heat treatment is performed at 800 to 900 ℃ for 3 to 7 hours.

19. In Paragraph 12, The above step (a) is, A step of forming a polymer solid electrolyte solution by mixing a polymer solid electrolyte precursor, a lithium precursor, and an organic solvent; A step of adding the LAZTP to the polymer solid electrolyte solution and stirring to form a polymer-oxide solid electrolyte solution; and A method for manufacturing a polymer-oxide composite double layer-based solid electrolyte membrane, comprising the step of applying the polymer-oxide solid electrolyte solution onto a substrate.

20. In Paragraph 19, A method for manufacturing a polymer-oxide composite double-layer-based solid electrolyte membrane, wherein the above stirring is performed for 10 to 14 hours.

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