Composite solid electrolyte, preparation method and application thereof, and solid sodium ion battery
By introducing conductive nanowires and binders into NASICON type solid electrolytes, the composite solid electrolytes are formed, which solves the problems of grain boundary impedance and mechanical strength, and achieves the improvement of high ionic conductivity and mechanical strength. It is suitable for solid sodium ion batteries.
Patent Information
- Application Number
- CN202510710734.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-29
- Publication Date
- 2025-08-29
AI Technical Summary
NASICON type solid electrolyte has problems such as large grain boundary impedance, high interface impedance and fragile mechanical properties, which affects its practical application.
A composite solid electrolyte, including a matrix layer and conductive nanowires, is distributed on the surface of the matrix layer and extends to the inside. Conductive nanowires are prepared by vapor deposition method, combining binder and sodium salt additives to form electrolytes with high ionic conductivity and high mechanical strength.
It effectively reduces the interface impedance, improves mechanical strength, forms a fast ion transmission channel, and improves the overall conductivity and mechanical properties.
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Figure CN120565786A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of solid electrolytes, and specifically relates to a composite solid electrolyte, a preparation method and application thereof, and a solid-state sodium ion battery. Background Art
[0002] Currently, NASICON (Na Super Ionic Conductor) solid electrolytes have attracted widespread attention due to their high ionic conductivity and good chemical stability. However, these materials still face the following technical bottlenecks: (1) large grain boundary impedance, which leads to reduced overall ionic conductivity; (2) poor solid-solid contact with electrode materials, resulting in high interfacial impedance; and (3) mechanical brittleness and poor processing performance. These problems have seriously restricted their practical application.
[0003] In existing technologies, researchers have attempted to improve performance through the following methods: (1) element doping to optimize crystal structure; (2) polymer compounding to enhance flexibility; and (3) introducing conductive additives to construct an ion transport network. However, these methods often struggle to simultaneously address both interfacial impedance and mechanical strength. For example, simple polymer compounding can reduce ionic conductivity, while the introduction of conductive additives can increase electronic conductivity, leading to short-circuit risks. Summary of the Invention
[0004] In order to overcome the above technical problems, the present invention provides a composite solid electrolyte, a preparation method and application thereof, and a solid-state sodium ion battery. The composite solid electrolyte of the present invention has low interface impedance and high mechanical strength.
[0005] The present invention solves the above technical problems through the following technical solutions.
[0006] The composite solid electrolyte provided by the present invention comprises a matrix layer and conductive nanowires;
[0007] The conductive nanowires are distributed on the surface of the base layer;
[0008] One end of the conductive nanowire extends into the interior of the base layer.
[0009] In the present invention, the composite solid electrolyte comprises the following raw materials in parts by mass: 35 to 55 parts of NASICON-type phosphate, 15 to 30 parts of conductive nanowires, 5 to 15 parts of a binder, and 3 to 8 parts of a sodium salt additive;
[0010] Preferably, the composite solid electrolyte comprises the following raw materials in parts by mass: 40 to 50 parts of NASICON-type phosphate, 18 to 28 parts of conductive nanowires, 8 to 13 parts of a binder, and 4 to 7 parts of a sodium salt additive.
[0011] In the present invention, the composition of the NASICON type phosphate is Na3+x M y Zr 2-x-y Si2PO 12 Where x = 0-0.5, y = 0-0.5, and M is Al, Ti, or V. Preferably, x = 0-0.3, y = 0-0.3, and M is Al. NASICON-type phosphates, through doping with elements such as Al, Ti, and V, balance structural stability and ionic conductivity, avoiding the high brittleness of traditional NASICON materials.
[0012] In the present invention, the conductive nanowires are composed of Na 11+a Sn 3+b AsS 12+c ; Among them, a=-0.3~0.3, b=-0.2~0.2, c=-0.3~0.3.
[0013] In the present invention, the conductive nanowires are made of sulfides, which have lower grain boundary resistance and higher sodium ion mobility than oxides. To ensure the continuity of the conductive network and avoid agglomeration, the average length of the conductive nanowires is 15-20 μm; the average diameter of the conductive nanowires is 30-50 nm.
[0014] In the present invention, the NASICON-type phosphate constitutes a matrix layer, the conductive nanowires are on the surface of the matrix layer and protrude from the matrix surface, and the longest protruding length of the conductive nanowires is 1 to 10 μm, preferably 3 to 8 μm.
[0015] In some preferred embodiments, the binder is PVDF-HFP copolymer, PVDF (polyvinylidene fluoride), PEO (polyethylene oxide) or PI (polyimide).
[0016] In some preferred embodiments, the sodium salt additive is NaTFSI (sodium bis(trifluoromethylsulfonyl)imide), NaODFB (sodium difluorooxalatoborate) or NaFSI (sodium bis(fluorosulfonyl)imide).
[0017] In this invention, high ionic conductivity requires a porous structure, but this sacrifices mechanical strength. Conductive nanowires pierce the NASICON substrate, forming ion transport channels. Direct contact between the nanowire ends and the electrodes reduces interfacial impedance, simultaneously overcoming the inherent strength limitations of conventional porous electrolytes.
[0018] In the present invention, the preparation method of the conductive nanowires is as follows: SnS2, As2S3, and Na2S are prepared by vapor deposition.
[0019] In some preferred embodiments, the temperature of the upstream zone of the vapor deposition reactor is 600-650°C.
[0020] In some preferred embodiments, the vapor deposition time is 10 to 24 hours, preferably 12 to 16 hours.
[0021] In some preferred embodiments, the argon gas flow rate for the vapor deposition is 45-60 sccm, preferably 50-55 sccm.
[0022] The sodium salt additive and flexible binder synergistically optimize the interfacial stability and inhibit the growth of sodium dendrites.
[0023] The preparation method of the composite solid electrolyte comprises the following steps:
[0024] S1. The raw materials of the composite solid electrolyte are mixed to form a slurry, and the slurry is cast into a film to obtain an electrolyte membrane;
[0025] S2. Hot-pressing the electrolyte membrane allows the conductive nanowires to penetrate the surface of the electrolyte membrane to obtain a composite solid electrolyte.
[0026] In S1, the coating speed of the film casting is 1.5 to 2.5 m / min.
[0027] In S1, the gap of the cast film is 100 to 300 μm, preferably 150 to 250 μm.
[0028] In S1, after the film is cast, infrared drying is performed at 50-100°C; preferably, gradient drying is performed within the range of 50-100°C after the film is cast.
[0029] In S2, the temperature of the hot pressing is 100-150°C, for example, 120°C.
[0030] In S2, the hot pressing pressure is 10-20 MPa, preferably 10-15 MPa.
[0031] In S2, the hot pressing time is 1 to 5 minutes, preferably 2 to 3 minutes.
[0032] The application of the aforementioned composite solid electrolyte, or the solid electrolyte prepared by the aforementioned composite solid electrolyte preparation method in high energy density solid-state sodium batteries, flexible electronic devices or microelectronic devices.
[0033] A solid-state sodium ion battery is composed of the aforementioned composite solid electrolyte or a composite solid electrolyte prepared by the aforementioned composite solid electrolyte preparation method. The other end of the conductive nanowire on the surface of the composite solid electrolyte is in contact with an electrode.
[0034] On the basis of conforming to the common sense in this field, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS
[0035] Figure 1 Schematic diagram of the simple structure of a solid-state sodium-ion battery.
[0036] Explanation of the accompanying symbols: 1. composite solid electrolyte; 2. positive electrode; 3. negative electrode; 4. positive electrode current collecting layer; 5. negative electrode current collecting layer.
[0037] Figure 2 Schematic diagram of the structure of the composite solid electrolyte. DETAILED DESCRIPTION
[0038] To facilitate understanding of the present invention, the present invention will be described more comprehensively and meticulously below in conjunction with preferred embodiments, but the protection scope of the present invention is not limited to the following specific embodiments.
[0039] Unless otherwise defined, all technical terms used hereinafter have the same meanings as those generally understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.
[0040] The "ranges" disclosed herein are defined in terms of lower and upper limits. A given range is defined by selecting a lower limit and an upper limit, and the selected lower and upper limits define the boundaries of the particular range. Ranges defined in this manner can be inclusive or exclusive of the end values and can be combined in any manner, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if the minimum range values listed are 1 and 2, and if the maximum range values listed are 3, 4, and 5, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this disclosure, unless otherwise indicated, the numerical range "ab" is an abbreviation for any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed herein, and "0-5" is merely an abbreviation for these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.
[0041] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.
[0042] Unless otherwise specified, all technical features and optional technical features of the present invention can be combined with each other to form a new technical solution.
[0043] Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, preferably sequentially. For example, "the method includes steps (a) and (b)" indicates that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, "the method may further include step (c)" indicates that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.
[0044] Unless otherwise specified, the terms "include" and "comprising" used in the present invention may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.
[0045] Unless otherwise specified, the term "or" is inclusive in this disclosure. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).
[0046]
Composite solid electrolyte
[0047] Example 1
[0048] The composite solid electrolyte of this embodiment includes a matrix layer and conductive nanowires;
[0049] The conductive nanowires are distributed on the surface of the substrate layer, and one end of the conductive nanowire extends into the interior of the substrate layer. Figure 2 Schematic diagram of the simple structure of the composite solid electrolyte;
[0050] The composite solid electrolyte is composed of the following raw materials in parts by weight: 50 parts of NASICON-type phosphate, 22 parts of conductive nanowires, 11 parts of binder (PVDF-HFP copolymer) and 7 parts of sodium salt additive (NaTFSI);
[0051] The composition of NASICON phosphate is Na3Zr2Si2PO 12 , which is a conventional NASICON type phosphate material in this field.
[0052] Preparation method of conductive nanowires: The actual feed ratio is SnS2:As2S3:Na2S with a molar ratio of 3:1:11. Na 11 Sn3AsS 12The temperature of the upstream zone of the vapor deposition was 600°C and the argon carrier gas flow rate was 55 sccm. After deposition for 12 hours, conductive nanowires were obtained; the average length of the conductive nanowires was 18 μm and the average diameter was 45 nm.
[0053] The preparation method of the composite solid electrolyte of this embodiment is as follows:
[0054] S1. The raw materials of the composite solid electrolyte are mixed and then slurried in a solvent (DMAc:acetone volume ratio of 1:2). After ball milling, the slurry is then tape-casted to obtain an electrolyte membrane;
[0055] The coating speed of the cast film was 2.0 m / min and the gap was 200 μm. After the cast film was formed, it was infrared dried at 50°C-90°C-60°C.
[0056] S2. The electrolyte membrane was hot-pressed at 120°C and 10 MPa for 2 minutes, so that the conductive nanowires pierced the surface of the electrolyte membrane. The longest protruding length of the conductive nanowires was 8 μm, thereby obtaining a composite solid electrolyte.
[0057] Example 2
[0058] The difference between this embodiment and embodiment 1 is that:
[0059] The composite solid electrolyte of this embodiment is composed of the following raw materials in parts by mass: 50 parts of NASICON phosphate, 26 parts of conductive nanowires, 9 parts of binder (PVDF) and 6 parts of sodium salt additive (NaFSI); the composition of NASICON phosphate is Na 3.2 Al 0.2 Zr 1.6 Si2PO 12 ;
[0060] Other raw materials, steps and parameters are the same as in Example 1.
[0061] Example 3
[0062] The difference between this embodiment and embodiment 1 is that:
[0063] The composite solid electrolyte of this embodiment is composed of the following raw materials in parts by mass: 45 parts of NASICON phosphate, 18 parts of conductive nanowires, 13 parts of binder and 7 parts of sodium salt additive;
[0064] Other raw materials, steps and parameters are the same as in Example 1.
[0065] Example 4
[0066] The difference between this embodiment and embodiment 1 is that:
[0067] The composite solid electrolyte of this embodiment is composed of the following raw materials in parts by weight: 35 parts of NASICON phosphate, 28 parts of conductive nanowires, 9 parts of binder and 3 parts of sodium salt additive;
[0068] Other raw materials, steps and parameters are the same as in Example 1.
[0069] Example 5
[0070] The difference between this embodiment and embodiment 1 is that:
[0071] The conductive nanowires are composed of Na 11.2 Sn 2.9 AsS 12.1 ;
[0072] During the preparation of the conductive nanowires, the temperature in the upstream zone of the vapor deposition was 630°C and the argon carrier gas flow rate was 60 sccm. The average length of the conductive nanowires was 20 μm. The average diameter of the conductive nanowires was 35 nm. The maximum protrusion length of the conductive nanowires was 7.3 μm.
[0073] Other raw materials, steps and parameters are the same as in Example 1.
[0074] Example 6
[0075] The difference between this embodiment and embodiment 1 is that:
[0076] S2. The electrolyte membrane was hot pressed at 150°C and 15 MPa for 3 min, so that the conductive nanowires pierced the surface of the electrolyte membrane. The longest protruding length of the conductive nanowires was 6.2 μm, thereby obtaining a composite solid electrolyte.
[0077] Other raw materials, steps and parameters are the same as in Example 1.
[0078] Comparative Example 1
[0079] The difference between this comparative example and Example 1 is:
[0080] The composite solid electrolyte of this embodiment is composed of the following raw materials in parts by mass: 50 parts of NASICON-type phosphate, 11 parts of binder and 6 parts of sodium salt additive; this comparative example does not contain conductive nanowires.
[0081] Other raw materials, steps and parameters are the same as in Example 1.
[0082] Comparative Example 2
[0083] The difference between this comparative example and Example 1 is:
[0084] The composite solid electrolyte of this embodiment is composed of the following raw materials by weight: 50 parts of NASICON phosphate, 11 parts of conductive nanowires, 10 parts of binder and 5 parts of sodium salt additive; the conductive nanowires added in this comparative example are less, and the more piercing structures can shorten the sodium ion migration path; while this comparative example lacks the fast ion transmission channel of conductive nanowires, ion transmission depends on the matrix layer. In addition, conductive nanowires can effectively bridge the pores of the matrix layer and improve toughness. When their content is insufficient, the porous structure of the matrix layer is not fully filled, and it is easy to penetrate the pores when subjected to force.
[0085] Other raw materials, steps and parameters are the same as in Example 1.
[0086] Solid-state sodium-ion battery
[0087] (1) Positive electrode
[0088] The mass ratio of active material: conductive agent: binder in the positive electrode material is 80-90:5-10:5-10;
[0089] The active material of the cathode material is Na3V2(PO4)3@C;
[0090] The conductive agent may be natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon nanotubes or carbon fibers;
[0091] The binder can be polyvinylidene fluoride, polyvinylidene fluoride-polyhexafluoropropylene copolymer, polyvinyl acetate, polyvinyl alcohol, polyvinyl ether, polyethylene, polyethylene oxide, alkylated polyethylene oxide, polypropylene, polymethyl (meth) acrylate, polyethyl (meth) acrylate, polytetrafluoroethylene, polyvinyl chloride, polyacrylonitrile, polyimide, polyvinyl pyridine or polyvinyl pyrrolidone; preferably, the binder can be polyvinylidene fluoride, polyvinyl butyral,
[0092] A positive electrode slurry was prepared according to the ratio of active material (Na3V2(PO4)3@C): conductive agent (acetylene black): binder (PVDF) = 90:5:5; the positive electrode slurry was coated on the surface of aluminum foil (as the positive electrode current collector), dried and roll-pressed to obtain a positive electrode sheet;
[0093] (2) Negative electrode
[0094] The negative electrode can be a sodium sheet, a sodium-tin alloy sheet or a sodium-antimony alloy sheet. This solution uses a sodium sheet as the negative electrode.
[0095] The negative electrode current collecting layer is copper foil;
[0096] (3) Assembly
[0097] The positive electrode, composite solid electrolyte and negative electrode are stacked and assembled in sequence to obtain a solid-state sodium ion battery. Figure 1 .
[0098]
Solid-state sodium-ion battery performance test
[0099] The ionic conductivity σ was tested using an electrochemical workstation in the frequency range of 1 MHz to 0.1 Hz, with an amplitude of 10 mV and a temperature controlled at 25 ± 0.5 °C.
[0100] Mechanical strength test: The composite solid electrolyte film was cut into samples of 10 mm (width) × 40 mm (length) × 0.05 mm (thickness). The samples were stretched to break at a rate of 1 mm / min using a universal material testing machine to measure the tensile strength.
[0101] Table 1
[0102] Project Number σ(mS / cm) Tensile strength (MPa) Example 1 9.74 13.4 Example 2 9.39 12.7 Example 3 9.27 13.5 Example 4 8.65 13.2 Example 5 8.83 13.1 Example 6 9.01 13.8 Comparative Example 1 7.36 11.6 Comparative Example 2 7.92 12.2
[0103] Unless otherwise specified, all raw materials, reagents, instruments, and equipment used in the present invention can be purchased from the market or prepared by existing methods. The specific embodiments described above further illustrate the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.
Claims
1. A composite solid electrolyte, characterized in that: including a substrate layer and conductive nanowires; The conductive nanowires are distributed on the surface of the base layer; One end of the conductive nanowire extends into the interior of the base layer.
2. The composite solid electrolyte according to claim 1, wherein The method comprises the following raw materials in parts by mass: 35 to 55 parts of NASICON-type phosphate, 15 to 30 parts of conductive nanowires, 5 to 15 parts of a binder, and 3 to 8 parts of a sodium salt additive; Preferably, the composite solid electrolyte comprises the following raw materials in parts by mass: 40 to 50 parts of NASICON-type phosphate, 18 to 28 parts of conductive nanowires, 8 to 13 parts of a binder, and 4 to 7 parts of a sodium salt additive.
3. The composite solid electrolyte according to claim 2, wherein Meet at least one of the following conditions ① to ④: ① The composition of the NASICON type phosphate is Na 3+x M y Zr 2-x-y Si2PO 12 ; Wherein, x=0-0.5, y=0-0.5, M is Al, Ti or V; ② The conductive nanowires are composed of Na 11+a Sn 3+b AsS 12+c , where a = -0.3 to 0.3, b = -0.2 to 0.2, c = -0.3 to 0.3; ③ The binder is PVDF-HFP copolymer, PVDF, PEO or PI; ④ The sodium salt additive is NaTFSI, NaODFB or NaFSI.
4. The composite solid electrolyte according to claim 3, wherein Meet at least one of the following conditions ① to ③: ① The average length of the conductive nanowires is 15 to 20 μm; ② The average diameter of the conductive nanowires is 30 to 50 nm; ③ The NASICON-type phosphate constitutes a matrix layer, and the conductive nanowires are on the surface of the matrix layer and protrude from the matrix surface. The longest protruding length of the conductive nanowires is 1 to 10 μm, preferably 3 to 8 μm.
5. The composite solid electrolyte according to claim 3, wherein The preparation method of the conductive nanowires is as follows: SnS2, As2S3, and Na2S are prepared by vapor deposition.
6. The composite solid electrolyte according to claim 5, characterized in that Meet at least one of the following conditions ① to ③: ① The temperature of the upstream zone of the vapor deposition reactor is 600-650°C; ② The vapor deposition time is 10 to 24 hours, preferably 12 to 16 hours; ③ The argon gas flow rate of the vapor deposition is 45 to 60 sccm, preferably 50 to 55 sccm.
7. The method for preparing a composite solid electrolyte according to any one of claims 1 to 6, wherein: The following steps are involved: S1. The raw materials of the composite solid electrolyte are mixed to form a slurry, and the slurry is cast into a film to obtain an electrolyte membrane; S2. Hot-pressing the electrolyte membrane allows the conductive nanowires to penetrate the surface of the electrolyte membrane to obtain a composite solid electrolyte.
8. The method for preparing a composite solid electrolyte according to claim 7, wherein: Meet at least one of the following conditions ① to ⑥: ① In S1, the coating speed of the cast film is 1.5 to 2.5 m / min; ② In S1, the gap of the cast film is 100 to 300 μm, preferably 150 to 250 μm; ③ In S1, after the film is cast, infrared drying is performed at 50-100° C.; ④ In S2, the temperature of the hot pressing is 100-150° C., for example, 120-130° C.; ⑤ In S2, the hot pressing pressure is 10-20 MPa, preferably 10-15 MPa; ⑥ In S2, the hot pressing time is 1 to 5 minutes, preferably 2 to 3 minutes.
9. Use of the composite solid electrolyte according to any one of claims 1 to 6, or the solid electrolyte prepared by the preparation method of the composite solid electrolyte according to any one of claims 7 to 8, in high energy density solid-state sodium batteries, flexible electronic devices or microelectronic devices.
10. A solid-state sodium ion battery, characterized in that: A composite solid electrolyte comprising the composite solid electrolyte according to any one of claims 1 to 6 or a composite solid electrolyte prepared by the method for preparing the composite solid electrolyte according to any one of claims 7 to 8; Wherein, the other end of the conductive nanowire on the surface of the composite solid electrolyte is in contact with the electrode.