Solid-state electrolyte and preparation method and application thereof

Abstract

The application provides a solid-state electrolyte and a preparation method and application thereof. The solid-state electrolyte comprises a first solid-state electrolyte layer and a second solid-state electrolyte layer which are arranged in a stack, the first solid-state electrolyte layer comprises a first polymer matrix and a first inorganic filler which is gradiently dispersed in the first polymer matrix, and the second solid-state electrolyte layer comprises a second polymer matrix and a second inorganic filler which is gradiently dispersed in the second polymer matrix. The solid-state electrolyte provided by the application has high ion conductivity and good compatibility and stability with a positive electrode or a negative electrode interface.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, specifically to the field of solid-state battery technology, and particularly to a solid electrolyte, its preparation method and application. Background Technology

[0002] Solid-state batteries are characterized by high safety and energy density, and their core lies in the solid-state electrolyte. Currently, solid-state electrolytes are mainly classified into organic polymer electrolytes, inorganic ceramic electrolytes, and organic / inorganic composite electrolytes.

[0003] Organic polymer electrolytes offer significant advantages, such as versatility and flexibility in shape and lightweight properties, making it easier to form good electrode / electrolyte contacts. However, their inherently low room-temperature ionic conductivity severely hinders their practical applications. Typically, pure organic solid electrolytes require in-situ thermosetting reactions of prepolymer solutions containing minimal amounts of high-functionality monomers, initiators, and electrolytes to produce gel-like organic solid electrolytes. This process generally requires high-temperature polymerization and has a long polymerization time. Inorganic ceramic electrolytes exhibit better ionic conductivity, but their high contact impedance at the electrode interface limits their applications.

[0004] Organic / inorganic composite electrolytes combine the advantages of both. Organic electrolytes have good flexibility and can withstand volume changes during battery charging and discharging, while they can make close contact with the electrode and reduce interfacial resistance. Inorganic solid electrolytes have high elastic modulus, which can suppress dendrite formation and improve safety.

[0005] CN109301320A discloses a vertically oriented composite solid electrolyte and its preparation method. The method involves preparing inorganic solid electrolyte nanofibers via electrospinning, then using an electric field orientation method to create a vertically oriented inorganic solid electrolyte framework. Finally, a composite solid electrolyte is formed by casting a polymer and lithium salt. This method utilizes nanofibers instead of nanoparticles to facilitate the preparation of a complete and uniform inorganic solid electrolyte framework and the rapid formation of Li... + The transport pathways all exhibit significant advantages, substantially improving the room-temperature ionic conductivity of the electrolyte to 10. -4 S·cm -1 .

[0006] CN115347231A discloses a composite solid electrolyte and its preparation method. The composite solid electrolyte comprises an inorganic solid electrolyte framework and a polymer solid electrolyte. The inorganic solid electrolyte framework contains interconnected three-dimensional channels, and the polymer solid electrolyte fills the three-dimensional channels.

[0007] CN115441048A discloses a composite electrolyte with a stable gradient distribution structure, a battery, and a preparation method thereof. The preparation method includes: obtaining a PDA-modified polymer spinning fiber membrane; obtaining an electrolyte precursor solution containing an inorganic ceramic filler, an in-situ polymerization precursor, a lithium salt, and an initiator; dropping the electrolyte precursor solution onto the PDA-modified polymer spinning fiber membrane; heating and polymerizing the resulting prepolymer membrane to obtain the composite electrolyte.

[0008] While existing technologies disclose many technical solutions for using organic / inorganic composite electrolytes, they suffer from problems such as complex preparation processes and the need for in-situ thermal curing reactions of prepolymerized solutions containing high-functionality monomers, initiators, electrolytes, etc.

[0009] Therefore, it is of great significance to provide a solid electrolyte with high ionic conductivity, good interface compatibility with positive or negative electrodes, simple preparation process, and no need for initiators or curing agents. Summary of the Invention

[0010] To address the shortcomings of existing technologies, the present invention aims to provide a solid electrolyte, its preparation method, and its applications. By designing the structure and composition of the solid electrolyte, the present invention improves the compatibility and stability of the solid electrolyte at the interface with the positive or negative electrode, and the solid electrolyte provided by the present invention exhibits high ionic conductivity.

[0011] To achieve this objective, the present invention employs the following technical solution:

[0012] In a first aspect, the present invention provides a solid electrolyte, the solid electrolyte comprising a first solid electrolyte layer and a second solid electrolyte layer stacked thereon, the first solid electrolyte layer comprising a first polymer matrix and a first inorganic filler gradient dispersed in the first polymer matrix, and the second solid electrolyte layer comprising a second polymer matrix and a second inorganic filler gradient dispersed in the second polymer matrix;

[0013] The first polymer matrix and the second polymer matrix have a three-dimensional interconnected structure.

[0014] In this invention, the terms "first" and "second" in the first electrolyte layer, first polymer matrix, first polymer, first inorganic filler, second electrolyte layer, second polymer matrix, second polymer, and second inorganic filler are used only to distinguish the components of the solid electrolyte and do not have any other special meaning.

[0015] In the solid electrolyte provided by this invention, the first polymer matrix can be in close contact with the positive electrode, which is beneficial for lithium ion transport, reduces contact impedance, and achieves a high charge-discharge rate. A second polymer matrix, which is more rigid than the positive electrode side, is disposed on the negative electrode side, which helps to suppress lithium dendrite growth and extend the cycle life of the solid-state battery. The first and second polymer matrices can form a three-dimensional interconnected structure within the bulk phase, forming a bulk interface with the inorganic phase. This facilitates ion conduction at the continuous interface of the composite film, and the inorganic phase can act as an ion insulator in this super-ionic conductor at the bulk interface, promoting rapid ion conduction. This invention introduces a first inorganic filler and a second inorganic filler into the first and second solid electrolyte layers, respectively. Utilizing the high elastic modulus of the inorganic filler, when applied to solid-state batteries, it can improve the mechanical strength of the battery and suppress dendrite formation, thus improving battery safety performance. The gradient distribution of the inorganic filler within the polymer matrix facilitates rapid ion transport at the organic-inorganic interface.

[0016] In the first solid electrolyte layer, the mass percentage of the first inorganic filler affects the conductivity of the solid electrolyte and the interfacial stability between the solid electrolyte and the positive electrode. If the amount of the first inorganic filler added is too small, the ion transport rate will decrease. If the amount of the first inorganic filler added is too large, the resistance will be too large, resulting in a decrease in the performance of the prepared solid battery and a shortened cycle life.

[0017] Preferably, in the first solid electrolyte layer, the mass percentage of the first polymer matrix is ​​30%-50%, for example, it can be 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48% or 50%, and the mass percentage of the first inorganic filler is 50%-70%, for example, it can be 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68% or 70%. The mass percentages of the first polymer matrix and the first inorganic filler mentioned above include, but are not limited to, the listed values. Other unlisted values ​​within the range are also applicable.

[0018] Preferably, in the first solid electrolyte layer, the mass percentage of the first inorganic filler decreases in a gradient along the direction away from the second solid electrolyte layer.

[0019] Preferably, in the first solid electrolyte layer, the mass of the first solid electrolyte layer is uniformly distributed. On the side closer to the second solid electrolyte layer, the mass percentage of the first inorganic filler is 80%-95%, for example, it can be 80%, 82%, 84%, 86%, 88%, 90%, 92%, 94%, or 95%. On the side farther from the second solid electrolyte layer, the mass percentage of the first inorganic filler is 5%-20%, for example, it can be 5%, 6%, 8%, 10%, 12%, 14%, 16%, 18%, or 20%. The mass percentage of the first inorganic filler is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0020] Preferably, in the first solid electrolyte layer, the mass of the first polymer matrix is ​​uniformly distributed. On the side closer to the second solid electrolyte layer, the mass ratio of the first inorganic filler to the first polymer matrix is ​​(80:20)-(95:5), for example, it can be 80:20, 82:18, 84:16, 86:14, 88:12, 90:10, 92:8, 94:6 or 95:5. On the side farther from the second solid electrolyte layer, the mass ratio of the first inorganic filler to the first polymer matrix is ​​(5:95)-(20:80), for example, it can be 5:95, 6:94, 8:92, 10:90, 12:88, 14:86, 16:84, 18:82 or 20:80. The above-mentioned mass ratio of the first inorganic filler to the first polymer matrix includes, but is not limited to, the listed values. Other unlisted values ​​within the range are also applicable.

[0021] In the second solid electrolyte layer, the mass percentage of the second inorganic filler affects the battery life, safety performance, and interfacial impedance of the solid electrolyte. If the amount of the second inorganic filler added is too small, lithium dendrites will grow faster and the solid battery life will be shorter. If the amount of the second inorganic filler added is too large, the impedance will be larger and the ion transport rate will be lower.

[0022] Preferably, in the second solid electrolyte layer, the mass percentage of the second polymer matrix is ​​30%-50%, for example, it can be 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48% or 50%, and the mass percentage of the second inorganic filler is 50%-70%, for example, it can be 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68% or 70%. The mass percentages of the first polymer matrix and the first inorganic filler mentioned above include, but are not limited to, the listed values. Other unlisted values ​​within the range are also applicable.

[0023] Preferably, in the second solid electrolyte layer, the mass percentage of the second inorganic filler decreases in a gradient along the direction close to the first solid electrolyte layer.

[0024] Preferably, in the second solid electrolyte layer, the mass of the second solid electrolyte layer is uniformly distributed. On the side away from the first solid electrolyte layer, the mass percentage of the second inorganic filler is 80%-95%, for example, it can be 80%, 82%, 84%, 86%, 88%, 90%, 92%, 94% or 95%. On the side closer to the first solid electrolyte layer, the mass percentage of the second inorganic filler is 5%-20%, for example, it can be 5%, 6%, 8%, 10%, 12%, 14%, 16%, 18% or 20%. The mass percentage of the second inorganic filler mentioned above includes but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0025] Preferably, in the second solid electrolyte layer, the mass of the second polymer matrix is ​​uniformly distributed. On the side away from the first solid electrolyte layer, the mass ratio of the second inorganic filler to the second polymer matrix is ​​(80:20)-(95:5), for example, it can be 80:20, 82:18, 84:16, 86:14, 88:12, 90:10, 92:8, 94:6 or 95:5. On the side closer to the first solid electrolyte layer, the mass ratio of the second inorganic filler to the second polymer matrix is ​​(5:95)-(20:80), for example, it can be 5:95, 6:94, 8:92, 10:90, 12:88, 14:86, 16:84, 18:82 or 20:80. The above-mentioned mass ratio of the second inorganic filler to the second polymer matrix includes, but is not limited to, the listed values. Other unlisted values ​​within the range are also applicable.

[0026] Preferably, the first polymer matrix comprises a first polymer, and the second polymer matrix comprises a second polymer.

[0027] In this invention, the first polymer matrix formed from the first polymer is more flexible than the second polymer matrix formed from the second polymer. The first polymer matrix can make close contact with the positive electrode, which is beneficial for lithium ion transport, reduces contact resistance, and achieves a high charge-discharge rate. Using the more rigid second polymer to form the second polymer matrix helps suppress the growth of lithium dendrites and extends the cycle life of the solid-state battery.

[0028] Preferably, the first polymer comprises any one or a combination of at least two of polyacrylonitrile, polyvinylidene fluoride, polysulfone, polyvinyl chloride, polytetrafluoroethylene, or polyvinylidene fluoride-hexafluoropropylene copolymer. Typical but non-limiting combinations include polyacrylonitrile and polyvinylidene fluoride, polyvinylidene fluoride and polysulfone, polysulfone and polyvinyl chloride, polyvinyl chloride and polytetrafluoroethylene, or polytetrafluoroethylene and polyvinylidene fluoride-hexafluoropropylene copolymer.

[0029] Preferably, the second polymer comprises any one or a combination of at least two of the following: polyethylene oxide, polymethyl methacrylate, polyvinylidene fluoride, polyethylene glycol, polyvinylpyrrolidone, polypropylene oxide, polyimide, polyurethane, chitosan, polyethylene succinate, polyethylene sebacic acid, polycaprolactone, polyvinyl alcohol, polymaleic anhydride, polyquaternary ammonium salt, or gelatin. Typical but non-limiting combinations include polyethylene oxide and polyvinylidene fluoride, polyethylene oxide and polymethyl methacrylate, polyethylene glycol and polyvinylpyrrolidone, polypropylene oxide and polyimide, polyurethane and chitosan, polyethylene succinate and polyethylene sebacic acid, polycaprolactone and polyvinyl alcohol, polymaleic anhydride and polyquaternary ammonium salt, or polyethylene oxide and gelatin.

[0030] Preferably, the first inorganic filler or the second inorganic filler each independently comprises any one or a combination of at least two of zirconium oxide, boron nitride, titanium dioxide, aluminum oxide, silicon oxide, cerium oxide, manganese oxide, molybdenum oxide, tin oxide, zinc oxide, lithium titanate, lithium aluminate, lithium lanthanum zirconium oxide, lithium lanthanum titanium oxide, or lithium titanium aluminum phosphate. Typical but non-limiting combinations include zirconium oxide and boron nitride, titanium dioxide and aluminum oxide, silicon oxide and cerium oxide, manganese oxide and molybdenum oxide, tin oxide and zinc oxide, lithium titanate and lithium aluminate, lithium lanthanum zirconium oxide and lithium lanthanum titanium oxide, or lithium titanium aluminum phosphate and zirconium oxide.

[0031] In this invention, the particle size of the first inorganic filler or the second inorganic filler is nano-sized inorganic particles.

[0032] Preferably, the particle size of the first inorganic filler or the second inorganic filler is independently 20nm-200nm, for example, it can be 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 110nm, 120nm, 130nm, 140nm, 150nm, 160nm, 170nm, 180nm, 190nm or 200nm, including but not limited to the listed values. Other unlisted values ​​within the range are also applicable. Preferably, it is 50-150nm, and more preferably 80-120nm.

[0033] Preferably, the thickness of the solid electrolyte is 15-120 μm, for example, it can be 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90, 95 μm, 100 μm, 105 μm, 110 μm, 115 μm or 120 μm, including but not limited to the listed values. Other unlisted values ​​within the range are also applicable. Preferably, it is 20-60 μm, and more preferably, it is 30-50 μm.

[0034] Preferably, the thickness ratio of the first solid electrolyte layer to the second solid electrolyte layer is 1:(0.5-2), for example, it can be 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.11, 1:1.12, 1:1.13, 1:1.14, 1:1.15, 1:1.16, 1:1.17, 1:1.18, 1:1.19, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9 or 1:2, including but not limited to the listed values. Other unlisted values ​​within the range are also applicable. Preferably, it is 1:(0.8-1.5), more preferably 1:(1-1.2).

[0035] Preferably, the solid electrolyte further includes an electrolyte salt.

[0036] In the solid electrolyte provided by this invention, the type of electrolyte salt can be selected according to the type of solid battery in which the solid electrolyte is applied.

[0037] Preferably, the electrolyte salt includes any one of lithium salt, sodium salt, or potassium salt.

[0038] Preferably, the lithium salt includes inorganic lithium salts and / or organic lithium salts.

[0039] Preferably, the inorganic lithium salt includes any one or a combination of at least two of lithium perchlorate, lithium hexafluorophosphate, or lithium tetrafluoroborate. Typical but non-limiting combinations include lithium perchlorate and lithium hexafluorophosphate, lithium perchlorate and lithium tetrafluoroborate, or lithium hexafluorophosphate and lithium tetrafluoroborate.

[0040] Preferably, the organolithium salt comprises any one or a combination of at least two of lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, or lithium bis(oxalatoborate). Typical non-limiting combinations include lithium trifluoromethanesulfonate and lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate and lithium bis(fluorosulfonyl)imide, lithium trifluoromethanesulfonate and lithium bis(oxalatoborate), lithium bis(trifluoromethanesulfonyl)imide and lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide and lithium bis(oxalatoborate), or lithium bis(fluorosulfonyl)imide and lithium bis(oxalatoborate).

[0041] Preferably, the sodium salt comprises any one or a combination of at least two of sodium hexafluorophosphate, sodium difluorosulfonyl imide, or sodium bis(trifluoromethanesulfonyl)imide. Typical but non-limiting combinations include sodium hexafluorophosphate and sodium difluorosulfonyl imide, sodium hexafluorophosphate and sodium bis(trifluoromethanesulfonyl)imide, or sodium difluorosulfonyl imide and sodium bis(trifluoromethanesulfonyl)imide.

[0042] Preferably, the potassium salt comprises potassium hexafluorophosphate and / or potassium difluorosulfonamide.

[0043] In a second aspect, the present invention provides a method for preparing a solid electrolyte as described in the first aspect, the method comprising:

[0044] Electrospinning the first polymer slurry and simultaneously spraying the first inorganic filler, the first inorganic filler being gradient-distributed in the first polymer matrix obtained by electrospinning, to obtain the first solid electrolyte layer;

[0045] The second polymer slurry is electrospun, and the second inorganic filler is sprayed simultaneously. The second inorganic filler is gradient-distributed in the second polymer matrix obtained by electrospinning to obtain the second solid electrolyte layer.

[0046] The first solid electrolyte layer and the second solid electrolyte layer are prepared in any order to obtain the solid electrolyte.

[0047] In this invention, a first polymer matrix and a second polymer matrix are prepared by electrospinning to form an organic secondary structure with a three-dimensional interconnected structure. Simultaneously, a first inorganic filler or a second inorganic filler is sprayed during electrospinning. By controlling the spray flow rate, the first or second inorganic filler is gradient-distributed within the formed organic secondary structure. The entire preparation process is simple and controllable, and the resulting solid electrolyte exhibits good structural and compositional consistency, which is beneficial for large-scale production.

[0048] Preferably, the preparation method further includes rolling the solid electrolyte obtained by electrospinning.

[0049] In this invention, the compression ratio is calculated as the thickness after rolling divided by the thickness before rolling. The compression ratio in this invention affects the performance of the solid-state battery by influencing the interfacial transport impedance of the first polymer matrix and the non-gel polymer matrix. If the compression ratio is too high, the three-dimensional interconnected structure in the first polymer matrix and the non-gel polymer matrix becomes too dense, resulting in a small specific surface area, hindering rapid transport. Salt ions cannot fully complex with the organic phase, drastically reducing the number of transportable ions. Conversely, if the compression ratio is too low, the three-dimensional interconnected structure in the first and second polymer matrices becomes too loose, resulting in insufficient contact between the organic and inorganic phases, leading to high impedance and hindering rapid ion transport.

[0050] Preferably, the compression ratio of the roller is 5%-35%, for example, it can be 5%, 10%, 15%, 20%, 25%, 30% or 35%, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0051] Preferably, the preparation method further includes immersing the rolled solid electrolyte in an electrolyte solution after the rolling process is completed.

[0052] In this invention, the types of electrolyte salts and solvents in the electrolyte solution are not specifically limited. The type of electrolyte salt is selected according to the type of solid-state battery in which the solid-state electrolyte is used, and the solvent used only needs to ensure that the electrolyte salt is completely dissolved and that there is no chemical reaction between them.

[0053] Preferably, the solvent includes N-methylpyrrolidone, N,N-dimethylformamide, acetonitrile, tetrahydrofuran, ethylene carbonate, propylene carbonate, butene carbonate, vinylene carbonate, propylene carbonate, fluoroethylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, γ-butyrolactone, γ-valerolactone, ethyl acetate, methyl formate, 2-methyltetrahydrofuran, dimethoxymethane, dimethoxypropane, 1,3-dioxolane, ethylene glycol dimethyl ether, 1,2-dimethoxyethane, dimethyl... Any one or at least two of sulfoxide, xylene, or fluoroether. Typical but not limited combinations include ethylene carbonate and propylene carbonate, butene carbonate and vinylene carbonate, propylene carbonate and fluoroethylene carbonate, dimethyl carbonate and diethyl carbonate, methyl ethyl carbonate and γ-butyrolactone, γ-valerolactone and ethyl acetate, methyl formate and 2-methyltetrahydrofuran, dimethoxymethane and dimethoxypropane, 1,3-dioxolane and ethylene glycol dimethyl ether, or 1,2-dimethoxyethane and dimethyl sulfoxide.

[0054] Preferably, the soaking time is 5 min to 30 min, for example, it can be 5 min, 10 min, 15 min, 20 min, 25 min or 30 min, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0055] The concentration of the electrolyte solution affects the transport effect at the organic-inorganic interface during impregnation. If the concentration is too high, salt ions will precipitate out; if the concentration is too low, it will not be completely complexed with the organic phase, resulting in fewer transportable ions, slower transport speed, and a decrease in the multiplier.

[0056] Preferably, the concentration of the electrolyte solution is 0.1-5 mol / L, for example, it can be 0.1 mol / L, 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L, 4 mol / L, 4.5 mol / L or 5 mol / L, including but not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 1-2 mol / L.

[0057] Preferably, after the impregnation is completed, the impregnated solid electrolyte is dried.

[0058] In this invention, the purpose of drying is to completely evaporate the solvent in the electrolyte solution.

[0059] Preferably, the drying temperature is 60℃-100℃, for example, it can be 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃ or 100℃, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0060] Preferably, the thickness of the dried solid electrolyte is 5μm-40μm, for example, it can be 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm or 40μm, including but not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 10μm-25μm.

[0061] Preferably, the thickness ratio of the first solid electrolyte layer to the second solid electrolyte layer is 1:(0.5-2), for example, it can be 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.11, 1:1.12, 1:1.13, 1:1.14, 1:1.15, 1:1.16, 1:1.17, 1:1.18, 1:1.19, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9 or 1:2, including but not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 1:(0.8-1.5), preferably 1:(1-1.2).

[0062] Thirdly, the present invention provides a solid-state battery, the solid-state battery comprising a positive electrode, a negative electrode and a solid electrolyte as described in the first aspect, wherein a first solid electrolyte layer of the solid electrolyte is opposite to the positive electrode and a second solid electrolyte layer of the solid electrolyte is opposite to the negative electrode.

[0063] Compared with the prior art, the present invention has the following beneficial effects:

[0064] (1) In the solid electrolyte provided by this invention, the first polymer matrix can be in close contact with the positive electrode, which is beneficial for lithium ion transport, reduces contact impedance, and achieves a high charge-discharge rate. A second polymer matrix with stronger rigidity than the positive electrode side is provided on the negative electrode side, which helps to suppress the growth of lithium dendrites and extend the cycle life of the solid-state battery. The first polymer matrix and the second polymer matrix can form a three-dimensional interconnected structure in the bulk phase, forming a bulk phase interface together with the inorganic phase. This is beneficial for ion conduction at the continuous interface of the composite film. The inorganic phase can act as an ion insulator in this bulk interface super-ionic conductor, which is beneficial for rapid ion conduction.

[0065] (2) In this invention, a first inorganic filler and a second inorganic filler are introduced into the first solid electrolyte layer and the second solid electrolyte layer, respectively. Utilizing the high elastic modulus of the inorganic filler, when applied to solid-state batteries, it can improve the mechanical strength of the battery and suppress dendrite formation, thereby enhancing the battery's safety performance. The gradient distribution of the inorganic filler within the polymer substrate facilitates rapid ion transport at the organic-inorganic interface.

[0066] (3) The present invention prepares a first polymer matrix or a second polymer matrix with a three-dimensional interconnected structure by electrospinning, and sprays a first inorganic filler or a second inorganic filler while electrospinning. By controlling the spray flow rate, the first inorganic filler or the second inorganic filler is gradient distributed in the first polymer matrix or the second polymer matrix. The entire preparation process is simple and controllable, and the solid electrolyte prepared has good consistency in structure and composition, which is conducive to large-scale production.

[0067] (3) The solid electrolyte provided by the present invention has high ionic conductivity when applied in solid batteries. Attached Figure Description

[0068] Figure 1 This is a schematic diagram of the structure of the solid electrolyte provided by the present invention.

[0069] Wherein, 1-first polymer matrix; 2-first inorganic filler; 3-second polymer matrix; 4-second inorganic filler.

[0070] Figure 2 This is a SEM image of the side of the first solid electrolyte layer away from the second solid electrolyte layer prepared in Example 1 of the present invention.

[0071] Figure 3 This is a SEM image of the first solid electrolyte layer prepared in Example 1 of the present invention, on the side near the second solid electrolyte layer.

[0072] Figure 4 This is a 0.1C cycle diagram of the soft-pack battery of Embodiments 1 and 4 of the present invention and Comparative Example 1. Detailed Implementation

[0073] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0074] Example 1

[0075] This embodiment provides a solid electrolyte, and the preparation method of the solid electrolyte is as follows:

[0076] (1) Preparation of the first solid electrolyte layer: electrospinning polyacrylonitrile slurry, while spraying zirconium oxide with a particle size of 100 nm, adjusting the flow rate of polyacrylonitrile and the spray flow rate of zirconium oxide, so that in the prepared first solid electrolyte layer, the mass percentage of polyacrylonitrile is 40% and the mass percentage of zirconium oxide is 60%, the mass of polyacrylonitrile is uniformly distributed, and the mass ratio of zirconium oxide to polyacrylonitrile is 90:10 on the side close to the second solid electrolyte layer, and 10:90 on the side away from the second solid electrolyte layer.

[0077] (2) Preparation of the second solid electrolyte layer: On the side where the mass ratio of zirconium oxide to polyacrylonitrile in the first solid electrolyte layer is 10:90, continue electrospinning polyethylene oxide, while spraying zirconium oxide with a particle size of 100 nm. Adjust the spray flow rate of polyethylene oxide and zirconium oxide so that the mass percentage of polyethylene oxide in the prepared second solid electrolyte layer is 40%, the mass percentage of zirconium oxide is 60%, the mass of polyethylene oxide is uniformly distributed, and on the side away from the first solid electrolyte layer, the mass ratio of zirconium oxide to polyethylene oxide is 90:10, and on the side closer to the first solid electrolyte layer, the mass ratio of zirconium oxide to polyethylene oxide is 10:90.

[0078] (3) Rolling step (2) The first solid electrolyte layer and the second solid electrolyte layer after electrospinning are compressed by 20%, and the first solid electrolyte layer and the second solid electrolyte layer after rolling are immersed in a 1 mol / L solution of lithium bis(fluorosulfonyl)imide in acetonitrile and N-methylpyrrolidone (NMP) for 30 min, and dried at 80°C to obtain the solid electrolyte.

[0079] The solid electrolyte prepared in this embodiment has a thickness of 25 μm, and the thickness ratio of the first solid electrolyte layer to the second solid electrolyte layer is 1:1.

[0080] Example 2

[0081] This embodiment provides a solid electrolyte, and the preparation method of the solid electrolyte is as follows:

[0082] (1) Preparation of the first solid electrolyte layer: electrospinning a mixture of polysulfone and polyvinylidene fluoride in a mass ratio of 1:2, while spraying boron nitride with a particle size of 80 nm. Adjust the flow rates of polysulfone and polyvinylidene fluoride and the spray flow rate of boron nitride so that the mass percentage of polysulfone and polyvinylidene fluoride in the prepared first solid electrolyte layer is 50%, the mass percentage of boron nitride is 50%, and the mass percentage of boron nitride is 80% on the side close to the second solid electrolyte layer and 20% on the side away from the second solid electrolyte layer. The mass percentage of boron nitride is 20% on the side away from the second solid electrolyte layer and 80% on the side.

[0083] (2) Preparation of the second solid electrolyte layer: On the side where the mass of boron nitride in the first solid electrolyte layer is 80% of the total mass of boron nitride, electrospinning of ethylene oxide and polyvinylidene fluoride slurry with a mass ratio of 1:2 is continued, while simultaneously spraying boron nitride with a particle size of 80 nm. The flow rates of ethylene oxide and polyvinylidene fluoride and the spray flow rate of boron nitride are adjusted so that the mass percentage of ethylene oxide and polyvinylidene fluoride in the prepared second solid electrolyte layer is 30%, the mass percentage of boron nitride is 70%, and on the side away from the first solid electrolyte layer, the mass percentage of boron nitride is 95% and the mass percentage of ethylene oxide and polyvinylidene fluoride is 5%, and on the side closer to the first solid electrolyte layer, the mass percentage of boron nitride is 5% and the mass percentage of ethylene oxide and polyvinylidene fluoride is 95%.

[0084] (3) Rolling step (2) The first solid electrolyte layer and the second solid electrolyte layer after electrospinning are compressed by 15%, and the first solid electrolyte layer and the second solid electrolyte layer after rolling are immersed in 0.1 mol / L lithium bis(fluorosulfonyl)imide acetonitrile and sulfolane (TMS) solution for 20 min and dried at 70°C to obtain the solid electrolyte.

[0085] The solid electrolyte prepared in this embodiment has a thickness of 22 μm, and the thickness ratio of the first solid electrolyte layer to the second solid electrolyte layer is 1:1.

[0086] Example 3

[0087] This embodiment provides a solid electrolyte, and the preparation method of the solid electrolyte is as follows:

[0088] (1) Preparation of the first solid electrolyte layer: electrospinning a mixture of polyacrylonitrile and polyvinylidene fluoride in a mass ratio of 1:2, and simultaneously spraying zirconium oxide with a particle size of 120 nm. Adjust the flow rates of polyacrylonitrile and polyvinylidene fluoride and the spray flow rate of zirconium oxide so that the mass percentage of polyacrylonitrile and polyvinylidene fluoride in the prepared first solid electrolyte layer is 30%, the mass percentage of zirconium oxide is 70%, and the mass percentage of zirconium oxide is 95% on the side close to the second solid electrolyte layer and 5% on the side away from the second solid electrolyte layer. The mass percentage of zirconium oxide is 5% on the side away from the second solid electrolyte layer and 95% on the side.

[0089] (2) Preparation of the second solid electrolyte layer: On the side where the mass of zirconium oxide in the first solid electrolyte layer is 90% of the total mass of zirconium oxide, continue electrospinning polymethyl methacrylate (PMMA) while spraying zirconium oxide with a particle size of 120 nm. Adjust the spray flow rate of PMMA and zirconium oxide so that the mass percentage of PMMA in the prepared second solid electrolyte layer is 50% and the mass percentage of zirconium oxide is 50%. On the side away from the first solid electrolyte layer, the mass percentage of zirconium oxide is 80% and the mass percentage of PMMA is 20%. On the side closer to the first solid electrolyte layer, the mass percentage of zirconium oxide is 20% and the mass percentage of PMMA is 80%.

[0090] (3) Rolling step (2) The first and second solid electrolyte layers after electrospinning are compressed by a ratio of 50%. The first and second solid electrolyte layers after rolling are immersed in a solution of 1 mol / L lithium hexafluorophosphate in ethylene carbonate: methyl ethyl carbonate: diethyl carbonate (1:1:1 Vol%) and containing 1% lithium difluorooxalate borate, 2% vinylene carbonate and 0.5% fluoroethylene carbonate for 20 min. The solid electrolyte is then dried at 90°C.

[0091] The solid electrolyte prepared in this embodiment has a thickness of 25 μm, and the thickness ratio of the first solid electrolyte layer to the second solid electrolyte layer is 1:1.15.

[0092] Example 4

[0093] This embodiment provides a solid electrolyte, and the preparation method of the solid electrolyte is as follows:

[0094] (1) Preparation of the first solid electrolyte layer: electrospinning a slurry of polyacrylonitrile and polyvinylidene fluoride with a mass ratio of 1:2, and simultaneously spraying boron nitride with a particle size of 50 nm. Adjust the spray flow rate of polyacrylonitrile, polyvinylidene fluoride and boron nitride so that the mass percentage of polyacrylonitrile and polyvinylidene fluoride in the prepared first solid electrolyte layer is 45%, the mass percentage of boron nitride is 55%, and the mass percentage of boron nitride is 85% on the side close to the second solid electrolyte layer and 15% on the side away from the second solid electrolyte layer. The mass percentage of boron nitride is 15% on the side away from the second solid electrolyte layer and 85% on the side.

[0095] (2) Preparation of the second solid electrolyte layer: On the side where the mass of boron nitride in the first solid electrolyte layer is 85% of the total mass of boron nitride, electrospinning is continued to produce a mixture of polyethylene oxide and polyethylene glycol with a mass ratio of 1:2. At the same time, boron nitride with a particle size of 50 nm is sprayed. The spray flow rates of polyethylene oxide, polyethylene glycol and boron nitride are adjusted so that the mass percentage of polyethylene oxide and polyethylene glycol in the prepared second solid electrolyte layer is 45% and the mass percentage of boron nitride is 55%. On the side away from the first solid electrolyte layer, the mass percentage of boron nitride is 85% and the mass percentage of polyethylene oxide and polyethylene glycol is 15%. On the side closer to the first solid electrolyte layer, the mass percentage of boron nitride is 15% and the mass percentage of polyethylene oxide and polyvinylidene fluoride is 85%.

[0096] (3) Rolling step (2) The first solid electrolyte layer and the second solid electrolyte layer after electrospinning are compressed by 15%, and the first solid electrolyte layer and the second solid electrolyte layer after rolling are immersed in a 1 mol / L lithium trifluoromethanesulfonate acetonitrile and propylene carbonate (PC) solution for 20 min, and dried at 95°C to obtain the solid electrolyte.

[0097] The solid electrolyte prepared in this embodiment has a thickness of 26 μm, and the thickness ratio of the first solid electrolyte layer to the second solid electrolyte layer is 1:2.

[0098] Example 5

[0099] This embodiment provides a solid electrolyte, and the preparation method of the solid electrolyte is as follows:

[0100] (1) Preparation of the first solid electrolyte layer: electrospinning a slurry of polyacrylonitrile and polyvinylidene fluoride in a mass ratio of 1:3, while spraying lithium lanthanum zirconium oxide with a particle size of 150 nm. Adjust the spray flow rate of polyacrylonitrile, polyvinylidene fluoride and lithium lanthanum zirconium oxide so that the mass percentage of polyacrylonitrile and polyvinylidene fluoride in the prepared first solid electrolyte layer is 35%, the mass percentage of lithium lanthanum zirconium oxide is 65%, and the mass percentage of lithium lanthanum zirconium oxide is 90% on the side close to the second solid electrolyte layer and 10% on the side away from the second solid electrolyte layer. The mass percentage of lithium lanthanum zirconium oxide is 10% on the side away from the second solid electrolyte layer and 90% on the side.

[0101] (2) Preparation of the second solid electrolyte layer: On the side where the mass of lithium lanthanum zirconium oxide in the first solid electrolyte layer is 90% of the total mass of lithium lanthanum zirconium oxide, continue electrospinning polypropylene oxide slurry, while spraying lithium lanthanum titanium oxide with a particle size of 150 nm. Adjust the spray flow rate of polypropylene oxide and lithium lanthanum titanium oxide so that the mass percentage of polypropylene oxide in the prepared second solid electrolyte layer is 35% and the mass percentage of lithium lanthanum titanium oxide is 65%. On the side away from the first solid electrolyte layer, the mass percentage of lithium lanthanum titanium oxide is 90% and the mass percentage of polypropylene oxide is 10%. On the side closer to the first solid electrolyte layer, the mass percentage of lithium lanthanum titanium oxide is 10% and the mass percentage of polypropylene oxide is 90%.

[0102] (3) Rolling step (2) The first and second solid electrolyte layers after electrospinning are compressed by a ratio of 30%. The first and second solid electrolyte layers after rolling are immersed in a 1 mol / L solution of lithium bis(difluorosulfonyl)imide (LiFSI) in ethylene carbonate (EC): dimethyl carbonate (DMC) (1:1 Vol%) for 15 min and dried at 65°C to obtain the solid electrolyte.

[0103] The solid electrolyte prepared in this embodiment has a thickness of 20 μm, and the thickness ratio of the first solid electrolyte layer to the second solid electrolyte layer is 1:2.

[0104] Example 6

[0105] This embodiment provides a solid electrolyte, and the preparation method of the solid electrolyte is as follows:

[0106] (1) Preparation of the first solid electrolyte layer: electrospinning a polyacrylonitrile and polyvinylidene fluoride slurry with a mass ratio of 1:0.8, and simultaneously spraying lithium lanthanum titanium oxide with a particle size of 20 nm. Adjust the spray flow rate of polyacrylonitrile, polyvinylidene fluoride and lithium lanthanum titanium oxide so that the mass percentage of polyacrylonitrile and polyvinylidene fluoride in the prepared first solid electrolyte layer is 40% and the mass percentage of lithium lanthanum titanium oxide is 60%. Polyacrylonitrile and polyvinylidene fluoride are uniformly distributed in the first solid electrolyte layer. On the side close to the second solid electrolyte layer, the mass ratio of lithium lanthanum titanium oxide to polyacrylonitrile and polyvinylidene fluoride is 90:10. On the side away from the second solid electrolyte layer, the mass ratio of lithium lanthanum titanium oxide to polyacrylonitrile and polyvinylidene fluoride is 10:90.

[0107] (2) Preparation of the second solid electrolyte layer: On the side where the mass of lithium lanthanum titanium oxide in the first solid electrolyte layer is 90% of the total mass of lithium lanthanum titanium oxide, continue electrospinning polyimide slurry, while spraying alumina with a particle size of 20 nm. Adjust the spray flow rate of polyimide and alumina so that the mass percentage of polyimide in the prepared second solid electrolyte layer is 40% and the mass percentage of alumina is 60%. The polyimide is uniformly distributed in the second solid electrolyte layer and is far away from the first solid electrolyte layer. The mass ratio of alumina to polyimide is 90:10. On the side closer to the first solid electrolyte layer, the mass ratio of alumina to polyimide is 10:90.

[0108] (3) Rolling step (2) The first solid electrolyte layer and the second solid electrolyte layer after electrospinning are compressed by 20%, and the first solid electrolyte layer and the second solid electrolyte layer after rolling are immersed in 1 mol / L lithium bis(fluorosulfonyl)imide in ethylene glycol dimethyl ether (DME) solution for 15 min and dried at 80°C to obtain the solid electrolyte.

[0109] The solid electrolyte prepared in this embodiment has a thickness of 15 μm, and the thickness ratio of the first solid electrolyte layer to the second solid electrolyte layer is 1:0.8.

[0110] Example 7

[0111] This embodiment provides a solid electrolyte, and the preparation method of the solid electrolyte is as follows:

[0112] (1) Preparation of the first solid electrolyte layer: electrospinning a polysulfone and polyvinylidene fluoride slurry with a mass ratio of 1:2, and simultaneously spraying zirconium oxide with a particle size of 200 nm. Adjust the spray flow rate of polysulfone, polyvinylidene fluoride and zirconium oxide so that the mass percentage of polysulfone and polyvinylidene fluoride in the prepared first solid electrolyte layer is 40%, the mass percentage of zirconium oxide is 60%, and the mass percentage of zirconium oxide is 90% on the side close to the second solid electrolyte layer and 10% on the side away from the second solid electrolyte layer. The mass percentage of zirconium oxide is 10% on the side away from the second solid electrolyte layer and 90% on the side away from the second solid electrolyte layer.

[0113] (2) Preparation of the second solid electrolyte layer: On the side where the mass of zirconium oxide in the first solid electrolyte layer is 90% of the total mass of zirconium oxide, continue electrospinning polyethylene oxide slurry, while spraying zirconium oxide with a particle size of 100 nm. Adjust the spray flow rate of polyethylene oxide and zirconium oxide so that the mass percentage of polyethylene oxide in the prepared second solid electrolyte layer is 40% and the mass percentage of zirconium oxide is 60%. On the side away from the first solid electrolyte layer, the mass percentage of zirconium oxide is 90% and the mass percentage of polyethylene oxide is 10%. On the side closer to the first solid electrolyte layer, the mass percentage of zirconium oxide is 10% and the mass percentage of polyethylene oxide is 90%.

[0114] (3) Rolling step (2) The first solid electrolyte layer and the second solid electrolyte layer after electrospinning are compressed by 20%, and the first solid electrolyte layer and the second solid electrolyte layer after rolling are immersed in 1 mol / L potassium hexafluorophosphate in ethylene glycol dimethyl ether (DME) solution for 20 min and dried at 80°C to obtain the solid electrolyte.

[0115] The solid electrolyte prepared in this embodiment has a thickness of 20 μm, and the thickness ratio of the first solid electrolyte layer to the second solid electrolyte layer is 1:0.5.

[0116] Example 8

[0117] This embodiment provides a solid electrolyte, and the preparation method of the solid electrolyte is as follows:

[0118] (1) Preparation of the first solid electrolyte layer: electrospinning a polysulfone and polyvinylidene fluoride slurry with a mass ratio of 1:2, and simultaneously spraying boron nitride with a particle size of 100 nm. Adjust the spray flow rate of polysulfone, polyvinylidene fluoride and boron nitride so that the mass percentage of polysulfone and polyvinylidene fluoride in the prepared first solid electrolyte layer is 40%, the mass percentage of boron nitride is 60%, and the mass percentage of boron nitride is 90% on the side close to the second solid electrolyte layer and 10% on the side away from the second solid electrolyte layer. The mass percentage of boron nitride is 10% on the side away from the second solid electrolyte layer and 90% on the side.

[0119] (2) Preparation of the second solid electrolyte layer: On the side where the mass of boron nitride in the first solid electrolyte layer is 90% of the total mass of boron nitride, continue electrospinning polyethylene oxide slurry, while spraying boron nitride with a particle size of 100 nm. Adjust the spray flow rate of polyethylene oxide and boron nitride so that the mass percentage of polyethylene oxide in the prepared second solid electrolyte layer is 40% and the mass percentage of boron nitride is 60%. On the side away from the first solid electrolyte layer, the mass percentage of boron nitride is 90% and the mass percentage of polyethylene oxide is 10%. On the side closer to the first solid electrolyte layer, the mass percentage of boron nitride is 10% and the mass percentage of polyethylene oxide is 90%.

[0120] (3) Rolling step (2) The first solid electrolyte layer and the second solid electrolyte layer after electrospinning are compressed by 20%, and the first solid electrolyte layer and the second solid electrolyte layer after rolling are immersed in a 1 mol / L sodium hexafluorophosphate propylene carbonate (PC) solution for 20 min and dried at 80°C to obtain the solid electrolyte.

[0121] The solid electrolyte prepared in this embodiment has a thickness of 25 μm, and the thickness ratio of the first solid electrolyte layer to the second solid electrolyte layer is 1:1.5.

[0122] Example 9

[0123] This embodiment provides a solid electrolyte. The preparation method of the solid electrolyte is the same as that in Example 1, except that the mass percentage of polyacrylonitrile in the first solid electrolyte layer is 60% and the mass percentage of zirconium oxide is 40%.

[0124] Example 10

[0125] This embodiment provides a solid electrolyte. The preparation method of the solid electrolyte is the same as that in Example 1, except that the mass percentage of polyethylene oxide in the second solid electrolyte layer is 60% and the mass percentage of zirconium oxide is 40%.

[0126] Comparative Example 1

[0127] This comparative example provides a solid electrolyte. The preparation method of the solid electrolyte is the same as that in Example 1, except that the polyethylene oxide in the second solid electrolyte layer is replaced with polyacrylonitrile in the first solid electrolyte layer.

[0128] Comparative Example 2

[0129] This comparative example provides a solid electrolyte. The preparation method of the solid electrolyte is the same as that in Example 1, except that the polyacrylonitrile in the first solid electrolyte layer is replaced with the polyethylene oxide in the second solid electrolyte layer.

[0130] Comparative Example 3

[0131] This comparative example provides a solid electrolyte. The preparation method of the solid electrolyte is the same as that in Example 1, except that zirconium oxide is not added to the first solid electrolyte layer.

[0132] Comparative Example 4

[0133] This comparative example provides a solid electrolyte. The preparation method of the solid electrolyte is the same as that in Example 1, except that zirconium oxide is not added to the second solid electrolyte layer.

[0134] Comparative Example 5

[0135] This comparative example provides a solid electrolyte. The preparation method of the solid electrolyte is the same as that in Example 1, except that zirconium oxide is not added to the solid electrolyte.

[0136] Comparative Example 6

[0137] This comparative example provides a solid electrolyte. The preparation method of the solid electrolyte is the same as that in Example 1, except that equal amounts of zirconium oxide are uniformly dispersed in the first solid electrolyte layer and the second solid electrolyte layer.

[0138] Performance testing:

[0139] The conductivity of the solid electrolytes prepared in all the above examples and comparative examples was tested by electrochemical impedance spectroscopy. The test results are shown in Table 1.

[0140] The morphology of the solid electrolyte prepared in Example 1 was characterized by SEM, such as... Figure 2 and Figure 3 As shown;

[0141] Using NCM811 as the positive electrode and lithium metal as the negative electrode, the solid electrolytes prepared in Examples 1, 4, and Comparative Example 1 were applied to solid-state batteries. The 0.1C cycle performance was tested under a voltage range of 2.8V-4.3V. The test results are shown below. Figure 4 .

[0142] Table 1

[0143] Ionic conductivity S / cm Example 1 <![CDATA[8.14E -04 ]]> Example 2 <![CDATA[1.45E -04 ]]> Example 3 <![CDATA[4.93E -04 ]]> Example 4 <![CDATA[6.25E -04 ]]> Example 5 <![CDATA[4.69E -04 ]]> Example 6 <![CDATA[2.08E -04 ]]> Example 7 <![CDATA[2.48E -05 ]]> Example 8 <![CDATA[2.34E -05 ]]> Example 9 <![CDATA[9.31E -06 ]]> Example 10 <![CDATA[9.63E -06 ]]> Comparative Example 1 <![CDATA[5.94E -06 ]]> Comparative Example 2 <![CDATA[3.42E -05 ]]> Comparative Example 3 <![CDATA[2.51E -06 ]]> Comparative Example 4 <![CDATA[2.32E -06 ]]> Comparative Example 5 <![CDATA[3.81E -06 ]]> Comparative Example 6 <![CDATA[4.69E -06 ]]>

[0144] The SEM image of the solid electrolyte prepared in Example 1 of this invention is shown below. Figure 2 and Figure 3 As shown, this invention prepares a polymer matrix with a three-dimensional interconnected structure by electrospinning, and achieves a gradient distribution of inorganic fillers in the polymer matrix by controlling the spray flow rate.

[0145] Based on the data results of Examples 1 to 6, the present invention designs the structure of the solid electrolyte and regulates the negative electrode / electrolyte interface and the positive electrode / electrolyte interface by using asymmetrical structures and compositions on the positive and negative electrode sides, thereby improving the compatibility and stability of the solid electrolyte with the positive or negative electrode interface. The solid electrolyte prepared by the present invention has high lithium-ion conductivity.

[0146] Based on the data results from Examples 1, 9, and 10, as well as Comparative Examples 3 to 5, both excessive and insufficient content of inorganic fillers in the solid electrolyte will lead to a deterioration in the performance of the solid electrolyte. If the first inorganic filler or the second inorganic filler or neither is added, the discharge rate will decrease, the electrochemical window will be reduced, the growth of lithium dendrites on the negative electrode side will be unable to be suppressed, and the battery life will decrease.

[0147] Based on the data results of Example 1, Comparative Examples 1 and 2, when the same gel polymer is used on the negative electrode side as on the positive electrode side, the interfacial compatibility between the solid electrolyte and the negative electrode deteriorates, resulting in a decrease in the performance of the solid-state battery based on the solid electrolyte. Similarly, when the same non-gel polymer is used on the positive electrode side as on the negative electrode side, the interfacial compatibility between the solid electrolyte and the positive electrode deteriorates, resulting in a decrease in the performance of the solid-state battery based on the solid electrolyte.

[0148] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A solid electrolyte, characterized in that, The solid electrolyte includes a first solid electrolyte layer and a second solid electrolyte layer stacked together. The first solid electrolyte layer includes a first polymer matrix and a first inorganic filler gradient dispersed in the first polymer matrix. The second solid electrolyte layer includes a second polymer matrix and a second inorganic filler gradient dispersed in the second polymer matrix. The first polymer matrix and the second polymer matrix have a three-dimensional interconnected structure.

2. The solid electrolyte as described in claim 1, characterized in that, In the first solid electrolyte layer, the mass percentage of the first polymer matrix is ​​30%-50%, and the mass percentage of the first inorganic filler is 50%-70%. Preferably, in the first solid electrolyte layer, the mass percentage of the first inorganic filler decreases gradually along the direction away from the second solid electrolyte layer; Preferably, in the first solid electrolyte layer, the mass of the first solid electrolyte layer is uniformly distributed, and the mass percentage of the first inorganic filler is 80%-95% on the side closer to the second solid electrolyte layer, and 5%-20% on the side farther away from the second solid electrolyte layer. Preferably, in the first solid electrolyte layer, the mass of the first polymer matrix is ​​uniformly distributed. On the side closer to the second solid electrolyte layer, the mass ratio of the first inorganic filler to the first polymer matrix is ​​(80:20)-(95:5), and on the side farther away from the second solid electrolyte layer, the mass ratio of the first inorganic filler to the first polymer matrix is ​​(5:95)-(20:80).

3. The solid electrolyte as described in claim 1 or 2, characterized in that, In the second solid electrolyte layer, the mass percentage of the second polymer matrix is ​​30%-50%, and the mass percentage of the second inorganic filler is 50%-70%. Preferably, in the second solid electrolyte layer, the mass percentage of the second inorganic filler decreases gradually along the direction close to the first solid electrolyte layer; Preferably, in the second solid electrolyte layer, the mass of the second solid electrolyte layer is uniformly distributed. On the side away from the first solid electrolyte layer, the mass percentage of the second inorganic filler is 80%-95%, and on the side closer to the first solid electrolyte layer, the mass percentage of the second inorganic filler is 5%-20%. Preferably, in the second solid electrolyte layer, the mass of the second polymer matrix is ​​uniformly distributed. On the side away from the first solid electrolyte layer, the mass ratio of the second inorganic filler to the second polymer matrix is ​​(80:20)-(95:5). On the side closer to the first solid electrolyte layer, the mass ratio of the second inorganic filler to the second polymer matrix is ​​(5:95)-(20:80).

4. The solid electrolyte according to any one of claims 1-3, characterized in that, The first polymer matrix includes a first polymer, and the second polymer matrix includes a second polymer; Preferably, the first polymer comprises any one or a combination of at least two of polyacrylonitrile, polyvinylidene fluoride, polysulfone, polyvinyl chloride, polytetrafluoroethylene, or polyvinylidene fluoride-hexafluoropropylene copolymer; Preferably, the second polymer comprises any one or a combination of at least two of the following: polyethylene oxide, polymethyl methacrylate, polyvinylidene fluoride, polyethylene glycol, polyvinylpyrrolidone, polypropylene oxide, polyimide, polyurethane, chitosan, polyethylene succinate, polyethylene sebacic acid, polycaprolactone, polyvinyl alcohol, polymaleic anhydride, polyquaternary ammonium salt, or gelatin. Preferably, the first inorganic filler or the second inorganic filler each independently comprises any one or a combination of at least two of zirconium oxide, boron nitride, titanium dioxide, aluminum oxide, silicon oxide, cerium oxide, manganese oxide, molybdenum oxide, tin oxide, zinc oxide, lithium titanate, lithium aluminate, lithium lanthanum zirconium oxide, lithium lanthanum titanium oxide, or lithium titanium aluminum phosphate. Preferably, the particle size of the first inorganic filler or the second inorganic filler is independently 20nm-200nm, preferably 50nm-150nm, and more preferably 80nm-120nm.

5. The solid electrolyte according to any one of claims 1-4, characterized in that, The thickness of the solid electrolyte is 15μm-120μm, preferably 20μm-60μm, and more preferably 30μm-50μm; Preferably, the thickness ratio of the first solid electrolyte layer to the second solid electrolyte layer is 1:(0.5-2), more preferably 1:(0.8-1.5), and even more preferably 1:(1-1.2).

6. The solid electrolyte according to any one of claims 1-5, characterized in that, The solid electrolyte also includes electrolyte salts; Preferably, the electrolyte salt includes any one of lithium salt, sodium salt, or potassium salt; Preferably, the lithium salt comprises inorganic lithium salt and / or organic lithium salt; Preferably, the inorganic lithium salt includes any one or a combination of at least two of lithium perchlorate, lithium hexafluorophosphate, or lithium tetrafluoroborate; Preferably, the organic lithium salt comprises any one or a combination of at least two of lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide, lithium bisfluorosulfonylimide, or lithium bis(oxalatoborate). Preferably, the sodium salt comprises any one or a combination of at least two of sodium hexafluorophosphate, sodium bis(fluorosulfonyl)imide, or sodium bis(trifluoromethylsulfonyl)imide. Preferably, the potassium salt comprises potassium hexafluorophosphate and / or potassium difluorosulfonamide.

7. A method for preparing a solid electrolyte as described in any one of claims 1-6, characterized in that, The preparation method includes: Electrospinning the first polymer slurry and simultaneously spraying the first inorganic filler, the first inorganic filler being gradient-distributed in the first polymer matrix obtained by electrospinning, to obtain the first solid electrolyte layer; The second polymer slurry is electrospun, and the second inorganic filler is sprayed simultaneously. The second inorganic filler is gradient-distributed in the second polymer matrix obtained by electrospinning to obtain the second solid electrolyte layer. The first solid electrolyte layer and the second solid electrolyte layer are prepared in any order to obtain the solid electrolyte.

8. The preparation method according to claim 7, characterized in that, The preparation method further includes rolling the solid electrolyte obtained by electrospinning; Preferably, the compression ratio of the roller press is 5%-35%.

9. The preparation method according to claim 7 or 8, characterized in that, The preparation method further includes immersing the rolled solid electrolyte in an electrolyte solution after the rolling process is completed; Preferably, the immersion time is 5 min to 30 min; Preferably, the concentration of the electrolyte solution is 0.1 mol / L-5 mol / L, more preferably 1 mol / L-2 mol / L; Preferably, after the impregnation is completed, the impregnated solid electrolyte is dried; Preferably, the drying temperature is 60℃-100℃; Preferably, the thickness of the dried solid electrolyte is 5μm-40μm, and more preferably 10μm-25μm; Preferably, the thickness ratio of the first solid electrolyte layer to the second solid electrolyte layer is 1:(0.5-2), more preferably 1:(0.8-1.5), and even more preferably 1:(1-1.2).

10. A solid-state battery, characterized in that, The solid-state battery includes a positive electrode, a negative electrode, and a solid electrolyte as described in any one of claims 1-6, wherein a first solid electrolyte layer of the solid electrolyte is opposite to the positive electrode, and a second solid electrolyte layer of the solid electrolyte is opposite to the negative electrode.

Images