A solid-state electrolyte with high ionic conductivity, a preparation method thereof, and a solid-state battery

Abstract

The present invention belongs to the field of solid-state lithium-ion battery electrolytes, and more specifically, the present invention relates to a high ionic conductivity solid-state electrolyte, characterized in that the solid-state electrolyte comprises: an electrolyte solution comprising a lithium salt and an organic solvent; a cross-linked polymer; a garnet-type oxide powder; and a polymer porous fiber.

Description

Technical Field

[0001] This invention relates to a solid electrolyte, particularly a solid electrolyte suitable for lithium-ion batteries, its preparation method, and a solid battery. Background Technology

[0002] Lithium-ion batteries are widely used in consumer electronics and electric vehicles due to their high energy density, lack of memory effect, and slow charge loss when not in use. Currently, most lithium-ion batteries on the market are liquid lithium-ion batteries. Because the electrolyte used is liquid and contains toxic, flammable, and volatile organic solvents, there are safety hazards during the use of liquid electrolytes, including electrolyte leakage, fire, and explosion. Specifically, because the electrolyte in liquid lithium-ion batteries cannot suppress the growth of lithium dendrites, when lithium dendrites pierce the lithium battery separator between the positive and negative electrodes, it can cause a short circuit, leading to performance degradation and, in severe cases, fire and explosion. Given the current shortcomings of liquid lithium-ion batteries, the use of solvent-free electrolytes or electrolytes containing only trace amounts of solvents has been a research and development goal for lithium-ion batteries.

[0003] Existing improvement technologies utilize solid-state batteries containing solid electrolytes to address the shortcomings of traditional liquid lithium-ion batteries. Specifically, a solid-state battery is a multi-layered structure consisting of a positive electrode, a solid electrolyte, and a negative electrode in sequence. Reducing the thickness of the solid electrolyte can increase ionic conductivity and shorten the lithium-ion diffusion path, thereby reducing the diffusion time and increasing the energy density and power density of the solid-state battery. However, in existing solid-state battery technologies, when the solid electrolyte is thin, it is difficult to maintain good mechanical properties, making it prone to breakage. This can lead to contact between the positive and negative electrodes, causing a short circuit in the lithium-ion battery. In view of the above-mentioned technological deficiencies, a solid electrolyte that provides excellent mechanical properties and flexibility in a thin-film state, and also has high ionic conductivity, is urgently needed to improve the lifespan, stability, and safety of solid-state batteries. Summary of the Invention

[0004] The purpose of this invention is to provide a solid electrolyte with high ionic conductivity, which can prevent lithium dendrite penetration and thus prevent contact between the positive and negative electrodes, stable battery performance, good flexibility, good processability, and high safety factor, as well as its preparation method and a solid battery.

[0005] To achieve the above objectives, the present invention provides a solid electrolyte with high ionic conductivity, characterized in that the solid electrolyte comprises: an electrolyte containing a lithium salt and an organic solvent; a cross-linked polymer; a garnet-type oxide powder; and a polymer porous fiber.

[0006] Preferably, the solid electrolyte further contains an initiator.

[0007] More preferably, the weight ratio of the crosslinked polymer to the electrolyte is 1:1 to 1:4.

[0008] More preferably, the weight ratio of the garnet-type oxide powder to the crosslinked polymer is 50:50 to 70:30.

[0009] More preferably, the lithium salt is formed by mixing two or more components selected from the group consisting of: LiTFSI (lithium bis(trifluoromethanesulfonyl)imide), LiFSI (lithium bis(fluorosulfonyl)imide), LiBOB (lithium bis(oxalateborate), LiDFOB (lithium difluorooxalateborate), and LiCF3SO3 (lithium trifluoromethanesulfonate).

[0010] More preferably, the organic solvent is formed by mixing two or more components selected from the group consisting of: EC (ethylene carbonate), PC (propylene carbonate), DMC (dimethyl carbonate), DEC (diethyl carbonate), and EMC (ethyl methyl carbonate).

[0011] More preferably, the crosslinking polymer is obtained by crosslinking PEGDA (polyethylene glycol diacrylate) and ETPTA (ethoxylated trimethylolpropane triacrylate) in a weight ratio of 1:A to 5:1, wherein: 0 <A<1。

[0012] More preferably, the garnet-type oxide powder is lithium lanthanum zirconium tantalum oxide (Li6.5La3Zr1.5Ta0.5O12, LLZTO) powder.

[0013] More preferably, the polymer porous fiber is a porous PTFE or a porous PI.

[0014] More preferably, the thickness of the solid electrolyte is ≤30µm.

[0015] More preferably, the polymer porous fiber has a thickness of 10 μm or a porosity of 60 to 95%.

[0016] More preferably, the polymer porous fiber has a plurality of nanopores vertically intersected therethrough, and the pore size of the nanopores is 5 to 10 μm.

[0017] More preferably, the median particle size (D50) of the garnet-type oxide powder is 50 to 500 μm.

[0018] More preferably, the initiator comprises azobisisobutyronitrile, azobisisoheptanenitrile, or dimethyl azobisisobutyrate.

[0019] More preferably, the initiator is 0.1 wt% to 2 wt% by weight of the total weight of the crosslinked polymer.

[0020] The present invention further provides a method for preparing a solid electrolyte with high ionic conductivity, characterized by comprising: an electrolyte preparation step, wherein a lithium salt and an organic solvent are uniformly stirred to obtain an electrolyte; a first mixed solution preparation step, wherein a crosslinked polymer is mixed with the electrolyte and stirred uniformly to obtain a first mixed solution; a second mixed solution preparation step, wherein a garnet oxide powder is added to the first mixed solution and stirred to obtain a second mixed solution; a precursor solution preparation step, wherein an initiator is added to the second mixed solution and stirred to obtain a precursor solution; a coating step, wherein the precursor solution is coated onto a polymer porous fiber to obtain a polymer porous fiber composite membrane; and a heat curing step, wherein the polymer porous fiber composite membrane is heat-cured to obtain the solid electrolyte with high ionic conductivity.

[0021] More preferably, the weight ratio of the crosslinked polymer to the electrolyte is 1:1 to 1:4.

[0022] More preferably, the weight ratio of the garnet-type oxide powder to the crosslinked polymer is 50:50 to 70:30.

[0023] More preferably, the garnet-type oxide powder is an LLZTO powder or a modified LLZTO powder.

[0024] More preferably, the preparation process of the modified LLZTO powder includes: a dispersion step, in which LLZTO powder is added to a modification solution and stirred and mixed at 70°C for 3 to 12 hours, and dispersed by ultrasound during stirring to obtain a modified mixed solution; a centrifugation step, in which the modified mixed solution is centrifuged and filtered to remove the liquid phase components contained therein and obtain a solid substance; and a purification step, in which the solid substance is washed with anhydrous ethanol to obtain the modified LLZTO powder.

[0025] More preferably, the modified solution comprises, by total volume: 70 to 90 vol% ethanol, 5 to 15 vol% deionized water, 2.5 to 7.5 vol% acetic acid, and 2.5 to 7.5 vol% silane coupling agent.

[0026] Preferably, the silane coupling agent comprises one or more of KH550, KH560 or KH570.

[0027] Preferably, the lithium salt is a mixture formed by mixing two or more components selected from the group consisting of: LiTFSI (lithium bis(trifluoromethanesulfonyl)imide), LiFSI (lithium bis(fluorosulfonyl)imide), LiBOB (lithium bis(oxalate)borate), LiDFOB (lithium difluoro(oxalate)borate), and LiCF3SO3 (lithium trifluoromethanesulfonate); the organic solvent is a mixture formed by mixing two or more components selected from the group consisting of: EC (ethylene carbonate), PC (propylene carbonate), DMC (dimethyl carbonate), DEC (diethyl carbonate), and EMC (ethyl methyl carbonate); the crosslinked polymer is obtained by crosslinking polymerization of PEGDA (polyethylene glycol diacrylate) and ETPTA (ethoxylated trimethylolpropane triacrylate) at a weight ratio of 1:A to 5:1, wherein 0<A<1; the initiator comprises azobisisobutyronitrile, azobisisoheptonitrile, or dimethyl azobisisobutyrate; or the polymer porous fiber is porous PTFE or porous PI.

[0028] Preferably, in the step of preparing the second mixed solution, the garnet-type oxide powder and the first mixed solution are stirred and mixed for ≧12 hours, and three times of ultrasonic oscillation are performed during the stirring and mixing, each lasting ≧10 minutes, to obtain the second mixed solution.

[0029] Preferably, in the step of preparing the precursor solution, the initiator comprises azobisisobutyronitrile, azobisisoheptonitrile, or dimethyl azobisisobutyrate, and the mixture is stirred for 2 hours to obtain the precursor solution.

[0030] Preferably, in the heating and curing step, the porous polymer fiber composite membrane is heated and cured at a temperature of 40 to 100°C for ≥2 hours to obtain the solid electrolyte with high ionic conductivity.

[0031] The present invention further provides a solid-state battery, characterized by comprising: a positive electrode layer; a solid electrolyte disposed on one side of the positive electrode layer, wherein the solid electrolyte comprises: an electrolyte, wherein the electrolyte comprises a lithium salt and an organic solvent; a crosslinked polymer; a garnet-type oxide powder; and a polymer porous fiber; and a negative electrode layer disposed on a side of the solid electrolyte opposite the positive electrode layer.

[0032] Preferably, the solid electrolyte further comprises an initiator.

[0033] More preferably, the weight ratio of the crosslinked polymer to the electrolyte is 1:1 to 1:4.

[0034] More preferably, the weight ratio of the garnet-type oxide powder to the crosslinked polymer is 50:50 to 70:30.

[0035] More preferably, the lithium salt is formed by mixing two or more components selected from the group consisting of: LiTFSI (lithium bis(trifluoromethanesulfonyl)imide), LiFSI (lithium bis(fluorosulfonyl)imide), LiBOB (lithium bis(oxalateborate), LiDFOB (lithium difluorooxalateborate), and LiCF3SO3 (lithium trifluoromethanesulfonate).

[0036] More preferably, the organic solvent is formed by mixing two or more components selected from the group consisting of: EC (ethylene carbonate), PC (propylene carbonate), DMC (dimethyl carbonate), DEC (diethyl carbonate), and EMC (ethyl methyl carbonate).

[0037] More preferably, the crosslinking polymer is obtained by crosslinking PEGDA (polyethylene glycol diacrylate) and ETPTA (ethoxylated trimethylolpropane triacrylate) in a weight ratio of 1:A to 5:1, wherein: 0 <A<1。

[0038] More preferably, the garnet-type oxide powder is lithium lanthanum zirconium tantalum oxide (Li6.5La3Zr1.5Ta0.5O12, LLZTO) powder.

[0039] More preferably, the polymer porous fiber is a porous PTFE or a porous PI.

[0040] More preferably, the thickness of the solid electrolyte is ≤30µm.

[0041] More preferably, the polymer porous fiber has a thickness of 10 μm or a porosity of 60 to 95%.

[0042] More preferably, the polymer porous fiber has a plurality of nanopores vertically intersected therethrough, and the pore size of the nanopores is 5 to 10 μm.

[0043] More preferably, the median particle size (D50) of the garnet-type oxide powder is 50 to 500 μm.

[0044] More preferably, the initiator comprises azobisisobutyronitrile, azobisisoheptanenitrile, or dimethyl azobisisobutyrate.

[0045] More preferably, the initiator is 0.1 wt% to 2 wt% by weight of the total weight of the crosslinked polymer.

[0046] The advantages of this invention compared to prior art are as follows: In current solid-state battery technology, the solid electrolyte used is hard and brittle, resulting in poor deformation resistance. It is prone to breakage under shock or pressure, leading to electrolyte leakage or short circuits caused by contact between the positive and negative electrodes. Furthermore, to avoid breakage, the solid electrolyte needs a certain thickness; however, greater thickness reduces ionic conductivity, thus slowing lithium-ion transfer. To address these problems, this invention improves the texture of the cross-linked polymer with the electrolyte, increasing its flexibility and elasticity. Therefore, after the precursor solution is immersed in the porous polymer fibers and cured, it provides a certain degree of softness while maintaining the mechanical properties of the solid electrolyte, making it less prone to breakage. Furthermore, in this invention, the weight ratio of garnet oxide powder to crosslinked polymer is high, and the modified garnet oxide powder can form a stable bridging structure with the crosslinked polymer. Therefore, after the precursor liquid is immersed in the porous polymer fiber, it can still maintain a uniform mixing state and will not stratify due to gravity. Thus, the solid electrolyte of this invention has high ionic conductivity stability and high electrochemical stability. In addition, when the thickness of the solid electrolyte is too thick, the ionic conductivity will decrease. However, when its thickness is too thin, its mechanical properties will be affected. To avoid this problem, this invention coats the precursor liquid onto PTFE. Since PTFE has good liquid absorption and rigidity, it can still provide stable mechanical properties even when the thickness is extremely thin, effectively block lithium dendrites, and avoid breakage. In addition, this invention limits the weight ratio of crosslinked polymer to electrolyte to 1:1 to 1:4, thus effectively controlling the thickness of the solid electrolyte to an extremely thin thickness and improving the ionic conductivity of the solid electrolyte. Attached Figure Description

[0047] Figures 1A to 1B A series of photographs illustrating the state relationship before and after the precursor solution is immersed in the polymer porous fiber;

[0048] Figures 2A to 2B This is a series of photographs illustrating the effects of obtaining solid electrolytes when the pore size of the polymer porous fibers is different;

[0049] Figures 3 to 4 The diagrams are a series of block diagrams illustrating the process flow of the method for preparing a solid electrolyte with high ionic conductivity according to the present invention.

[0050] Figures 5A to 5B A series of photographs are presented to illustrate the effect of LLZTO powder modification on the dispersion uniformity of the precursor liquid.

[0051] Figure 6 This is a structural diagram used to illustrate the structural features of the solid-state battery of the present invention. DETAILED DESCRIPTION OF EMBODIMENTS

[0052] To make the above and / or other objects, effects and features of the present invention more obvious and understandable, preferred embodiments are specifically described below in detail:

[0053] An object of the present invention is to provide a "solid electrolyte with high ionic conductivity 2", characterized in that the solid electrolyte 2 comprises: an electrolyte solution 3, wherein the electrolyte solution 3 comprises a lithium salt and an organic solvent; a cross-linked polymer 4; a garnet-type oxide powder 5; and a porous polymer fiber 6. In a preferred embodiment, the solid electrolyte 2 further comprises an initiator. In another preferred embodiment, in order for the solid electrolyte 2 to maintain good ionic conductivity, the weight ratio of the cross-linked polymer 4 to the electrolyte solution 3 is 1:1 to 1:4. In still another preferred embodiment, in order to control the thickness of the solid electrolyte 2 so that it has certain flexibility and avoid cracking when being squeezed, the weight ratio of the garnet-type oxide powder 5 to the cross-linked polymer 4 is controlled to be 50:50 to 70:30. In yet another preferred embodiment, the purpose of adding the lithium salt is that the lithium salt can accelerate the transmission efficiency of lithium ions, so as to transmit high-density energy in a short time. Wherein the lithium salt is formed by mixing two or more components selected from the following group: LiTFSI (lithium bis(trifluoromethanesulfonyl)imide), LiFSI (lithium bis(fluorosulfonyl)imide), LiBOB (lithium bis(oxalato)borate), LiDFOB (lithium difluoro(oxalato)borate), and LiCF3SO3 (lithium trifluoromethanesulfonate), but is not limited thereto. Preferably, the concentration of the lithium salt is 1 to 3 M, but is not limited thereto. In yet another preferred embodiment, the organic solvent is formed by mixing two or more components selected from the following group: EC (ethylene carbonate), PC (propylene carbonate), DMC (dimethyl carbonate), DEC (diethyl carbonate), and EMC (ethyl methyl carbonate), but is not limited thereto. In yet another preferred embodiment, the cross-linked polymer 4 is obtained by cross-linking polymerization of PEGDA (polyethylene glycol diacrylate) and ETPTA (ethoxylated trimethylolpropane triacrylate) at a weight ratio of 1:A to 5:1, wherein 0<A<1. In yet another preferred embodiment, the garnet-type oxide powder 5 is lithium lanthanum zirconium tantalum oxide (Li6.5La3Zr1.5Ta0.5O12, LLZTO) powder. In yet another preferred embodiment, the porous polymer fiber 6 is porous PTFE or porous PI, but is not limited thereto.

[0054] Preferably, to ensure the solid electrolyte 2 of the present invention has sufficient softness and elasticity to prevent breakage under pressure, the thickness of the solid electrolyte 2 is ≤30 μm. In a preferred embodiment, to control the total thickness of the solid electrolyte 2, the thickness of the polymer porous fiber 6 is 10 μm; and to increase the ability of the polymer porous fiber 6 to adsorb the precursor liquid, the porosity of the polymer porous fiber 6 is 60 to 95%. In another preferred embodiment, to allow the precursor liquid to penetrate the polymer porous fiber 6, a plurality of nanopores 8 are vertically perforated on the polymer porous fiber 6, and the pore size of the nanopores 8 is 5 to 10 μm. In yet another preferred embodiment, the median particle size (D50) of the garnet-type oxide powder 5 is 50 to 500 μm. In yet another preferred embodiment, the initiator comprises azobisisobutyronitrile, azobisisoheptanenitrile, or dimethyl azobisisobutyrate. In another preferred embodiment, the initiator comprises 0.1 wt% to 2 wt% of the total weight of the crosslinked polymer 4, preferably 0.5 wt%.

[0055] Preferably, such as Figure 1A As shown, the images are obtained by scanning porous PTFE fibers using a scanning electron microscope (SEM); and as shown... Figure 1B The image shown is an SEM scan of porous PTFE fibers after they have been impregnated with a precursor solution. Specifically, porous PTFE fibers are non-flammable, possess good rigidity, and exhibit excellent hydrophilicity, resulting in high absorption and retention rates of the precursor solution. Furthermore, due to the high modulus of the porous PTFE fibers, they effectively prevent puncture by lithium dendrites 9 and prevent short circuits caused by contact between the positive and negative electrodes, thus significantly improving the safety of solid-state batteries. In a preferred embodiment, to allow the precursor solution to impregnate the porous PTFE fibers, a plurality of nanopores 8 are formed on the porous PTFE fibers. Additionally, to further enhance the impregnation effect of the precursor solution, the nanopores 8 extend from one side of the porous PTFE fiber to the other, and the central axes of any two nanopores 8 are parallel to each other. Furthermore, the nanopores 8 extend vertically from one side of the porous PTFE fiber to the other, allowing the precursor liquid to easily penetrate into them while also shortening the movement path of lithium ions, thereby achieving excellent ionic conductivity.

[0056] Preferably, such as Figure 2A The image shows an example of a solid electrolyte 2 obtained after coating a precursor solution onto a porous PTFE fiber with a pore size of 0.2 μm, allowing it to impregnate the porous PTFE fiber, and then curing. The image also shows... Figure 2BThe figure shows an example of a solid electrolyte 2 obtained by coating a precursor liquid onto a porous PTFE fiber with a pore size of 5 μm, allowing it to wet the porous PTFE fiber and solidify.

[0057] Another object of the present invention is to provide a "method for preparing a solid electrolyte 2 with high ionic conductivity", such as Figure 3 As shown, the process includes: an electrolyte preparation step S1, in which a lithium salt and an organic solvent are uniformly stirred to obtain an electrolyte 3; a first mixed solution preparation step S2, in which a crosslinked polymer 4 is mixed with the electrolyte 3 and stirred uniformly to obtain a first mixed solution; a second mixed solution preparation step S3, in which a garnet oxide powder 5 is added to the first mixed solution and stirred to obtain a second mixed solution; a precursor solution preparation step S4, in which an initiator is added to the second mixed solution and stirred to obtain a precursor solution; a coating step S5, in which the precursor solution is coated onto a polymer porous fiber 6 to obtain a polymer porous fiber 6 composite membrane; and a heat curing step S6, in which the polymer porous fiber 6 composite membrane is heat-cured to obtain the high ionic conductivity solid electrolyte 2. In a preferred embodiment, in order to maintain good ionic conductivity of the solid electrolyte 2, the weight ratio of the crosslinked polymer 4 to the electrolyte 3 is 1:1 to 1:4. In another preferred embodiment, to control the thickness of the solid electrolyte 2 and give it a certain degree of flexibility to prevent breakage under pressure, the weight ratio of the garnet oxide powder 5 to the crosslinked polymer 4 is 50:50 to 70:30. In yet another preferred embodiment, the garnet oxide powder 5 is an LLZTO powder or a modified LLZTO powder. Specifically, to ensure good dispersibility of the precursor solution and prevent precipitation or stratification, a modified LLZTO powder is added in the second mixed solution preparation step S3. Figure 4As shown, the preparation process of the modified LLZTO powder comprises: a dispersion step S7, adding an LLZTO powder to a modification solution, stirring and mixing the same at a temperature of 70°C for 3 to 12 hours, and performing dispersion by ultrasonic waves during stirring, so as to obtain a modified mixed solution; a centrifugation step S8, centrifuging and filtering the modified mixed solution to remove the liquid phase component contained therein, and obtaining a solid substance; and a purification step S9, washing the solid substance with anhydrous ethanol to obtain the modified LLZTO powder. In addition, when the stirring time in the dispersion step S7 is 12 hours, the effect of grafting functional groups on the surface of the LLZTO powder is optimal. In another preferred embodiment, based on the total volume of the modification solution, the modification solution comprises: 70 to 90 vol% of ethanol, 5 to 15 vol% of deionized water, 2.5 to 7.5 vol% of acetic acid, and 2.5 to 7.5 vol% of a silane coupling agent. In another preferred embodiment, the silane coupling agent comprises one or more of KH550, KH560 or KH570. In another preferred embodiment: the lithium salt is formed by mixing two or more components selected from the group consisting of LiTFSI (lithium bis(trifluoromethanesulfonyl)imide), LiFSI (lithium bis(fluorosulfonyl)imide), LiBOB (lithium bis(oxalato)borate), LiDFOB (lithium difluoro(oxalato)borate), and LiCF3SO3 (lithium trifluoromethanesulfonate); the organic solvent is formed by mixing two or more components selected from the group consisting of EC (ethylene carbonate), PC (propylene carbonate), DMC (dimethyl carbonate), DEC (diethyl carbonate), and EMC (ethyl methyl carbonate); the crosslinked polymer 4 is obtained by crosslinking polymerization of PEGDA (polyethylene glycol diacrylate) and ETPTA (ethoxylated trimethylolpropane triacrylate) at a weight ratio of 1:A to 5:1, wherein 0<A<1; the initiator comprises azobisisobutyronitrile, azobisisoheptonitrile, or dimethyl azobisisobutyrate; or the polymer porous fiber 6 is porous PTFE or porous PI. In another preferred embodiment, all the methods described above of the present invention are completed in a glove box, and the water content and oxygen content in the glove box are controlled at a concentration of <1ppm, so as to avoid that excessively high water and oxygen values cause a high content of oxygen to capture free radicals and form stable peroxy radicals, thereby slowing down or preventing the polymerization of free radicals.

[0058] Preferably, in step S3 of preparing the second mixed solution, the garnet-type oxide powder 5 is stirred and mixed with the first mixed solution for ≥12 hours, and ultrasonic vibration is performed three times during the stirring and mixing process, each lasting ≥10 minutes, to obtain the second mixed solution. In a preferred embodiment, in step S4 of preparing the precursor liquid, the initiator comprises azobisisobutyronitrile, azobisisoheptanenitrile, or dimethyl azobisisobutyrate, and is stirred and mixed for 2 hours to obtain the precursor liquid. In yet another preferred embodiment, in step S6 of heating and curing, the polymer porous fiber 6 composite membrane is heated and cured at a temperature of 40 to 100°C for ≥2 hours to obtain the solid electrolyte 2 with high ionic conductivity.

[0059] Preferably, due to the large difference in surface energy between the inorganic material and the polymer, they easily form an agglomeration effect when mixed in a solvent. Specifically, in the precursor liquid provided by the present invention, the total weight ratio of LLZTO powder and crosslinked polymer 4 exceeds 50 wt% based on the total weight of the precursor liquid. Therefore, in the present invention, LLZTO powder and crosslinked polymer 4 can form an excellent agglomeration effect in the precursor liquid, and the dispersion is uniform and precipitation is not easily generated. In addition, to further enhance the agglomeration effect of LLZTO powder and crosslinked polymer 4, the LLZTO powder is first modified with a silane coupling agent to obtain a modified LLZTO powder. The silane coupling agent used includes KH550 or KH560, but is not limited to these. Specifically, because silane coupling agents are compounds of organic functional groups and silanoxy groups, they readily form a bonding layer at the interface between organic and inorganic materials. Therefore, the modified LLZTO powder and crosslinked polymer 4 can be more tightly bridged, making the precursor solution less prone to precipitation. Specifically, such as... Figure 5A As shown, this includes: precursor solutions prepared with LLZTO powder and modified LLZTO powder, respectively; and as shown... Figure 5B As shown, to... Figure 5A The precipitation patterns of the two precursor solutions were observed after the prepared precursor solutions were allowed to stand for 2 days. It was found that the precursor solution prepared with modified LLZTO powder remained uniformly mixed after 2 days of standing; while the precursor solution prepared with unmodified LLZTO powder precipitated after 2 days of standing, exhibiting stratification. Therefore, based on the above results, it can be concluded that adding modified LLZTO powder can increase the uniform dispersion of the precursor solution. Because it is less prone to precipitation, its ionic conductivity is stable and will not affect the charge / discharge efficiency or overall performance of the battery. In a preferred embodiment, the LLZTO powder is cubic in phase and its median particle size (D50) is 50 to 500 nm.

[0060] Another object of the present invention is to provide a "solid-state battery", such as Figure 6As shown, comprising: a positive electrode layer 1; a solid electrolyte 2 disposed on one side of the positive electrode layer 1, wherein the solid electrolyte 2 comprises: an electrolyte solution 3 comprising a lithium salt and an organic solvent; a cross-linked polymer 4; garnet-type oxide powder 5; a polymer porous fiber 6; and a negative electrode layer 7 disposed on a side of the solid electrolyte 2 opposite to the positive electrode layer 1. In a preferred embodiment, the solid electrolyte 2 further comprises an initiator. In another preferred embodiment, in order to enable the solid electrolyte 2 to maintain good ionic conductivity, the weight ratio of the cross-linked polymer 4 to the electrolyte solution 3 is 1:1 to 1:4. In still another preferred embodiment, in order to control the thickness of the solid electrolyte 2 so that it has certain flexibility and avoid fracture when squeezed, the weight ratio of the garnet-type oxide powder 5 to the cross-linked polymer 4 is 50:50 to 70:30. In still another preferred embodiment, the lithium salt is formed by mixing two or more components selected from the following group: LiTFSI (lithium bis(trifluoromethanesulfonyl)imide), LiFSI (lithium bis(fluorosulfonyl)imide), LiBOB (lithium bis(oxalato)borate), LiDFOB (lithium difluoro(oxalato)borate), and LiCF3SO3 (lithium trifluoromethanesulfonate). In still another preferred embodiment, the organic solvent is formed by mixing two or more components selected from the following group: EC (ethylene carbonate), PC (propylene carbonate), DMC (dimethyl carbonate), DEC (diethyl carbonate), and EMC (ethyl methyl carbonate). In still another preferred embodiment, the cross-linked polymer 4 is obtained by cross-linking polymerization of PEGDA (polyethylene glycol diacrylate) and ETPTA (ethoxylated trimethylolpropane triacrylate) at a weight ratio of 1:A to 5:1, wherein 0<A<1. In still another preferred embodiment, the garnet-type oxide powder 5 is lithium lanthanum zirconium tantalum oxide (Li6.5La3Zr1.5Ta0.5O12, LLZTO) powder. In still another preferred embodiment, the polymer porous fiber 6 is porous PTFE or porous PI. In still another preferred embodiment, the thickness of the solid electrolyte 2 is ≤ 30um. In still another preferred embodiment, the thickness of the polymer porous fiber 6 is 10um, or the porosity thereof is 60 to 95%. In still another preferred embodiment, a plurality of nano-channels 8 vertically penetrate through the polymer porous fiber 6, and the pore diameter of the nano-channels 8 is 5 to 10um. In still another preferred embodiment, the median particle size (D50) of the garnet-type oxide powder 5 is 50 to 500um. In still another preferred embodiment, the initiator comprises azobisisobutyronitrile, azobisisoheptonitrile, or dimethyl azobisisobutyrate. In still another preferred embodiment, based on the total weight of the cross-linked polymer 4, the weight percentage of the initiator is 0.1wt% to 2wt%. Specifically, as Figure 6 As shown in the enlarged partial view, the garnet oxide powder 5 is LLZTO powder, and in the precursor solution, the crosslinked polymer 4 is connected in series with the LLZTO powder, thus forming a high-speed lithium-conducting network. In addition, since the high-speed lithium-conducting network is filled and penetrated in the nanopores 8 of the polymer porous fiber 6, the polymer porous fiber 6 can protect and support the high-speed lithium-conducting network. Furthermore, the final solid electrolyte 2 can still maintain excellent mechanical properties and flexibility in an extremely thin state, which can greatly improve the processability and processing yield when it is used to prepare lithium-ion batteries.

[0061] Preferably, in order to evaluate the effect of different parameter conditions or manufacturing processes on the ionic conductivity of solid electrolyte 2, Examples 1 to 10 are provided below, and the relevant condition parameters are summarized in Table 1 below.

[0062] The following provides a detailed preparation process for the high ionic conductivity solid electrolyte 2 of "Example 1" of the present invention, wherein the prepared solid electrolyte 2 has a thickness of 20 μm and an ionic conductivity of 5.2 × 10⁻⁶ at a temperature of 25°C. -4 (S / cm)

[0063] Step 1: EC and DEC are added sequentially to a lithium salt and stirred to obtain an electrolyte 3, wherein the lithium salt contains 0.5M LiTFSI and 1M LIDFOB;

[0064] Step 2: Mix a PEGDA monomer and an ETPTA monomer at a weight ratio of 1:5 to obtain a crosslinked polymer 4.

[0065] Step 3: Mix the crosslinked polymer 4 and the electrolyte 3 in a 1:1 weight ratio to obtain a first mixed solution;

[0066] Step 4: Add LLZTO powder to the first mixed solution, stir and mix for ≥12 hours, and perform ultrasonic dispersion 3 times during the stirring and mixing process, each lasting 10 minutes, to obtain a second mixed solution, wherein the weight ratio of the LLZTO powder to the crosslinked polymer 4 is 50:50.

[0067] Step 5: Add an initiator to the second mixed solution and stir at room temperature for 1 hour to obtain a precursor solution, wherein: the initiator is azobisisobutyronitrile, and the weight percentage of the initiator is 0.1wt% to 2wt% based on the total weight of the crosslinked polymer 4.

[0068] Step 6: Using a 50µm doctor blade, the precursor liquid is applied to the surface of a porous PTFE fiber and allowed to stand for 1 hour to allow the precursor liquid to fully penetrate the pore structure of the porous PTFE fiber before curing, thereby obtaining a porous PTFE fiber composite; and

[0069] Step 7: Place the porous PTFE fiber composite on a heating table and heat it at 60°C for 2 hours to obtain a solid electrolyte 2 with high ionic conductivity.

[0070] Preferably, to evaluate whether the weight ratio of LLZTO powder to crosslinking polymer 4 affects the ionic conductivity of solid electrolyte 2, Examples 2 to 5 are provided for comparison with Example 1. The only difference between Examples 2 to 5 and Example 1 is the adjustment of the weight ratio of LLZTO powder to crosslinking polymer 4; all other preparation processes and parameters are the same as in Example 1. Specifically, in Example 2, after adjusting the weight ratio of LLZTO powder to crosslinking polymer 4 to 50:45, the thickness of the obtained solid electrolyte 2 increased to 22 μm, and the ionic conductivity at 25°C decreased to 4.6 × 10⁻⁶. -4 (S / cm); In "Example 3", after adjusting the weight ratio of LLZTO powder to crosslinked polymer 4 to 60:40, the thickness of the obtained solid electrolyte 2 increased to 25 μm, and the ionic conductivity at 25°C decreased to 3.2 × 10⁻⁶. -4 (S / cm); In "Example 4", after adjusting the weight ratio of LLZTO powder to crosslinked polymer 4 to 65:35, the thickness of the obtained solid electrolyte 2 increased to 28 μm, and the ionic conductivity at 25°C decreased to 1.8 × 10⁻⁶. -4 (S / cm); In "Example 5", after adjusting the weight ratio of LLZTO powder to crosslinked polymer 4 to 70:30, the thickness of the obtained solid electrolyte 2 increased to 30 μm, and the ionic conductivity at 25°C decreased to 1.3 × 10⁻⁶. -4 (S / cm)

[0071] Preferably, to evaluate whether the weight ratio of crosslinked polymer 4 to electrolyte 3 affects the ionic conductivity of solid electrolyte 2, Examples 6 to 9 are provided for comparison with Example 1. The only difference between Examples 6 to 9 and Example 1 is the adjustment of the weight ratio of crosslinked polymer 4 to electrolyte 3; all other preparation processes and parameters are the same as in Example 1. Specifically, in Example 6, after adjusting the weight ratio of crosslinked polymer 4 to electrolyte 3 to 1:1.75, the thickness of the obtained solid electrolyte 2 remained unchanged, and the ionic conductivity at 25°C increased to 5.8 × 10⁻⁶.-4 (S / cm); In "Example 7", after adjusting the weight ratio of crosslinked polymer 4 to electrolyte 3 to 1:2.5, the thickness of the obtained solid electrolyte 2 remained unchanged, and the ionic conductivity at 25°C increased to 6.3 × 10⁻⁶. -4 (S / cm); In "Example 8", after adjusting the weight ratio of crosslinked polymer 4 to electrolyte 3 to 1:3.25, the thickness of the obtained solid electrolyte 2 remained unchanged, and the ionic conductivity at 25°C increased to 6.8 × 10⁻⁶. -4 (S / cm); and in "Example 9", after adjusting the weight ratio of crosslinked polymer 4 to electrolyte 3 to 1:4, the thickness of the obtained solid electrolyte 2 remained unchanged, and the ionic conductivity at 25°C increased to 7.1 × 10⁻⁶. -4 (S / cm)

[0072] Preferably, the following provides a pair of examples 1, which differs from Examples 1 to 9 in that: its precursor solution does not contain LLZTO powder, but instead, LLZTO powder is first coated on one side of a porous PTFE fiber to form an LLZTO powder layer, and then a precursor solution is coated on the side of the LLZTO powder layer opposite to the porous PTFE fiber. Specifically, its preparation method includes: First step: EC and DEC are added sequentially to a lithium salt and stirred to obtain an electrolyte 3, wherein: the lithium salt contains: 0.5M LiTFSI and 1M LIDFOB; Second step: a PEGDA monomer and an ETPTA monomer are mixed at a weight ratio of 1:5 to obtain a crosslinked polymer 4; Third step: the crosslinked polymer 4 and the electrolyte 3 are uniformly mixed at a weight ratio of 1:1. The process involves: 1) obtaining a first mixed solution; 2) adding an initiator to the first mixed solution and stirring at room temperature for 1 hour to obtain a precursor solution, wherein the initiator is azobisisobutyronitrile (AIORT), and the weight percentage of the initiator is 0.1 wt% to 2 wt% based on the total weight of the crosslinked polymer 4; 3) using a 50 μm scraper to coat the precursor solution onto the surface of a porous PTFE fiber coated with LLZTO powder on one side, and allowing it to stand for 1 hour to allow the precursor solution to fully penetrate the pore structure of the porous PTFE fiber coated with LLZTO powder on one side before curing, thereby obtaining a porous PTFE fiber composite; and 4) placing the porous PTFE fiber composite on a heating table and heating it at 60°C for 2 hours to obtain a high ionic conductivity solid electrolyte 2. The thickness of the high ionic conductivity solid electrolyte 2 in Comparative Example 1 remained unchanged, and the ionic conductivity was maintained at 5.2 × 10⁻⁶. -4 (S / cm)

[0073] Table 1. Parameters and conditions for each embodiment, and ionic conductivity

[0074]

[0075] The advantages of this invention compared to prior art are as follows: In current solid-state battery technology, the solid electrolyte 2 used is hard and brittle, resulting in poor deformation resistance. It is prone to breakage under shock or pressure, leading to leakage of the electrolyte 3 or short circuits caused by contact between the positive and negative electrodes. Furthermore, to avoid breakage, the solid electrolyte 2 needs a certain thickness; however, a greater thickness reduces its ionic conductivity, thus slowing down lithium-ion transfer. To solve these problems, this invention improves the texture of the cross-linked polymer 4 with the electrolyte 3, increasing its flexibility and elasticity. Therefore, after the precursor solution is immersed in the porous polymer fiber 6 and cured, it provides a certain degree of softness while maintaining the mechanical properties of the solid electrolyte 2, making it less prone to breakage. Furthermore, in this invention, the weight ratio of garnet oxide powder 5 to crosslinked polymer 4 is high, and the modified garnet oxide powder 5 can form a stable bridging structure with the crosslinked polymer 4. Therefore, after the precursor liquid is immersed in the polymer porous fiber 6, it can still maintain a uniform mixing state and will not stratify due to gravity. Thus, the solid electrolyte 2 of this invention has high ionic conductivity stability and high electrochemical stability. In addition, when the thickness of the solid electrolyte 2 is too thick, the ionic conductivity will decrease. However, when its thickness is too thin, its mechanical properties will be affected. To avoid this problem, this invention coats the precursor liquid onto PTFE. Since PTFE has good liquid absorption and rigidity, it can still provide stable mechanical properties even when the thickness is extremely thin, effectively blocking lithium dendrites 9 and preventing breakage. In addition, this invention limits the weight ratio of crosslinked polymer 4 to electrolyte 3 to 1:1 to 1:4, thus effectively controlling the thickness of the solid electrolyte 2 to an extremely thin thickness and improving the ionic conductivity of the solid electrolyte 2.

[0076] However, the above description is only a preferred embodiment of the present invention, and should not be construed as limiting the scope of patent protection of the present invention. Therefore, any simple equivalent changes and modifications made in accordance with the scope of patent protection and the contents of the specification of the present invention shall still fall within the scope of patent protection of the present invention.

Claims

1. A solid electrolyte with high ionic conductivity, characterized in that, The solid electrolyte comprises: An electrolyte comprising a lithium salt and an organic solvent; A crosslinked polymer obtained by crosslinking a first acrylate and a second acrylate, wherein the first acrylate includes polyethylene glycol diacrylate and the second acrylate includes ethoxylated trimethylolpropane triacrylate; A garnet-type oxide powder, which is tandemly attached to the crosslinked polymer via a silane coupling agent; as well as Polymer porous fibers; The weight ratio of the crosslinked polymer to the electrolyte is 1:1.75 to 1:

4. The thickness of the solid electrolyte is 20 μm to 30 μm.

2. The solid electrolyte with high ionic conductivity according to claim 1, characterized in that, The solid electrolyte further contains an initiator.

3. The solid electrolyte with high ionic conductivity according to claim 1, characterized in that, Wherein, the weight ratio of the garnet-type oxide powder to the crosslinked polymer is 50:50 to 70:

30.

4. The solid electrolyte with high ionic conductivity according to claim 1, characterized in that, The lithium salt is formed by mixing two or more components selected from the group consisting of: lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium bis(oxalateborate), lithium difluorooxalateborate, and lithium trifluoromethanesulfonate.

5. The solid electrolyte with high ionic conductivity according to claim 1, characterized in that, The organic solvent is formed by mixing two or more components selected from the group consisting of: ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

6. The solid electrolyte with high ionic conductivity according to claim 1, characterized in that, The first acrylate and the second acrylate are crosslinked and polymerized in a weight ratio of 1:A to 5:1, wherein: 0 <A<1。 7. The solid electrolyte with high ionic conductivity according to claim 1, characterized in that, The garnet-type oxide powder is Li 6.5 La3Zr 1.5 Ta 0.5 O 12 powder.

8. The solid electrolyte with high ionic conductivity according to claim 1, characterized in that, The polymer porous fiber is a porous PTFE or a porous PI.

9. The solid electrolyte with high ionic conductivity according to claim 1, characterized in that, The polymer porous fiber has a thickness of 10 μm or a porosity of 60 to 95%.

10. A solid electrolyte with high ionic conductivity according to claim 1, characterized in that, The polymer porous fiber has a plurality of nanopores vertically inserted, and the pore size of the nanopores is 5 to 10 μm.

11. A solid electrolyte with high ionic conductivity according to claim 1, characterized in that, The median particle size D50 of the garnet-type oxide powder is 50 to 500 μm.

12. The solid electrolyte with high ionic conductivity according to claim 2, characterized in that, The initiator comprises azobisisobutyronitrile, azobisisoheptanenitrile, or dimethyl azobisisobutyrate.

13. The solid electrolyte with high ionic conductivity according to claim 2, characterized in that, The initiator is 0.1 wt% to 2 wt% by weight based on the total weight of the crosslinked polymer.

14. A method for preparing a solid electrolyte with high ionic conductivity, characterized in that, Include: An electrolyte preparation step involves uniformly stirring a lithium salt and an organic solvent to obtain an electrolyte. A first mixed solution preparation step involves mixing a cross-linked polymer with the electrolyte and stirring until homogeneous to obtain a first mixed solution; A second mixed solution preparation step involves adding a garnet-type oxide powder to the first mixed solution and stirring to obtain a second mixed solution; A precursor solution preparation step involves adding an initiator to the second mixed solution and stirring to obtain a precursor solution. A coating step involves coating the precursor solution onto a polymer porous fiber to obtain a polymer porous fiber composite membrane; and A heating and curing step is used to heat and cure the polymer porous fiber composite membrane to obtain the solid electrolyte with high ionic conductivity. in The crosslinked polymer is obtained by crosslinking and polymerizing a first acrylate and a second acrylate. The first acrylate includes polyethylene glycol diacrylate, and the second acrylate includes ethoxylated trimethylolpropane triacrylate. The garnet-type oxide powder is surface modified by a silane coupling agent. The weight ratio of the crosslinked polymer to the electrolyte is 1:1.75 to 1:4; The thickness of the solid electrolyte is 20 μm to 30 μm.

15. The method according to claim 14, characterized in that, The weight ratio of the garnet-type oxide powder to the crosslinked polymer is 50:50 to 70:

30.

16. The method according to claim 14, characterized in that, The garnet-type oxide powder is a Li 6.5 La3Zr 1.5 Ta 0.5 O 12 Powder, or a modified Li 6.5 La3Zr 1.5 Ta 0.5 O 12 powder.

17. The method according to claim 16, characterized in that, The modified Li 6.5 La3Zr 1.5 Ta 0.5 O 12 The powder preparation process includes: A dispersion step, to dissipate a Li 6.5 La3Zr 1.5 Ta 0.5 O 12 The powder is added to a modified solution and stirred at 70°C for 3 to 12 hours, and dispersed by ultrasound during stirring to obtain a modified mixed solution. A centrifugation step is performed to centrifuge and filter the modified mixed solution to remove the liquid phase components contained therein and obtain a solid substance; as well as A purification step involves washing the solid substance with anhydrous ethanol to obtain the modified Li. 6.5 La3Zr 1.5 Ta 0.5 O 12 powder.

18. The method according to claim 17, characterized in that, The modified solution comprises, by total volume: 70 to 90 vol% ethanol, 5 to 15 vol% deionized water, 2.5 to 7.5 vol% acetic acid, and 2.5 to 7.5 vol% silane coupling agent.

19. The method according to claim 18, characterized in that, The silane coupling agent comprises one or more of KH550, KH560, or KH570.

20. The method according to claim 14, characterized in that, in: The lithium salt is formed by mixing two or more components selected from the group consisting of: lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium bis(oxalateborate), lithium difluorooxalateborate, and lithium trifluoromethanesulfonate. The organic solvent is formed by mixing two or more components selected from the group consisting of: ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate. The first acrylate and the second acrylate are crosslinked and polymerized in a weight ratio of 1:A to 5:1, wherein: 0 <A<1; The initiator comprises: azobisisobutyronitrile, azobisisoheptanenitrile, or dimethyl azobisisobutyrate; or The polymer porous fiber is a porous PTFE or a porous PI.

21. The method according to claim 14, characterized in that, In the second mixed solution preparation step, the garnet oxide powder is stirred and mixed with the first mixed solution for ≥12 hours, and ultrasonic vibration is performed three times during the stirring and mixing process, each lasting ≥10 minutes, to obtain the second mixed solution.

22. The method according to claim 14, characterized in that, In the precursor preparation step, the initiator comprises azobisisobutyronitrile, azobisisoheptanenitrile, or dimethyl azobisisobutyrate, and is stirred and mixed for 2 hours to obtain the precursor.

23. The method according to claim 14, characterized in that, In the heating and curing step, the polymer porous fiber composite membrane is heated and cured at a temperature of 40 to 100°C for ≥ 2 hours to obtain the solid electrolyte with high ionic conductivity.

24. A solid-state battery, characterized in that, Include: A positive electrode layer; A solid electrolyte, disposed on one side of the positive electrode layer, has a thickness of 20 μm to 30 μm, wherein the solid electrolyte comprises: An electrolyte comprising a lithium salt and an organic solvent; A crosslinked polymer is obtained by crosslinking a first acrylate and a second acrylate, wherein the first acrylate includes polyethylene glycol diacrylate and the second acrylate includes ethoxylated trimethylolpropane triacrylate; the weight ratio of the crosslinked polymer to the electrolyte is 1:1.75 to 1:

4. A garnet-type oxide powder, which is tandemly attached to the crosslinked polymer via a silane coupling agent; as well as A polymer porous fiber; and A negative electrode layer is disposed on the side of the solid electrolyte opposite to the positive electrode layer.

25. The solid-state battery according to claim 24, characterized in that, The solid electrolyte further contains an initiator.

26. The solid-state battery according to claim 24, characterized in that, Wherein, the weight ratio of the garnet-type oxide powder to the crosslinked polymer is 50:50 to 70:

30.

27. The solid-state battery according to claim 24, characterized in that, The lithium salt is formed by mixing two or more components selected from the group consisting of: lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium bis(oxalateborate), lithium difluorooxalateborate, and lithium trifluoromethanesulfonate.

28. The solid-state battery according to claim 24, characterized in that, The organic solvent is formed by mixing two or more components selected from the group consisting of: ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

29. The solid-state battery according to claim 24, characterized in that, The first acrylate and the second acrylate are crosslinked and polymerized in a weight ratio of 1:A to 5:1, wherein: 0 <A<1。 30. The solid-state battery according to claim 24, characterized in that, The garnet-type oxide powder is Li 6.5 La3Zr 1.5 Ta 0.5 O 12 powder.

31. The solid-state battery according to claim 24, characterized in that, The polymer porous fiber is a porous PTFE or a porous PI.

32. The solid-state battery according to claim 24, characterized in that, The polymer porous fiber has a thickness of 10 μm or a porosity of 60 to 95%.

33. The solid-state battery according to claim 24, characterized in that, The polymer porous fiber has a plurality of nanopores vertically inserted, and the pore size of the nanopores is 5 to 10 μm.

34. The solid-state battery according to claim 24, characterized in that, The median particle size D50 of the garnet-type oxide powder is 50 to 500 μm.

35. The solid-state battery according to claim 25, characterized in that, The initiator comprises azobisisobutyronitrile, azobisisoheptanenitrile, or dimethyl azobisisobutyrate.

36. The solid-state battery according to claim 25, characterized in that, The initiator is 0.1 wt% to 2 wt% by weight based on the total weight of the crosslinked polymer.

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