Solid-state battery diaphragm

Abstract

The utility model discloses a solid-state battery diaphragm. Comprising an inorganic solid electrolyte layer, a first high-molecular polymer matrix layer, a second high-molecular polymer matrix layer, a first nano-ceramic coating, a second nano-ceramic coating, a third nano-ceramic coating and a fourth nano-ceramic coating, the second nano ceramic coating is arranged on the outer surface of the second high-molecular polymer matrix layer; wherein the surface of the first nano ceramic coating and the surface of the second nano ceramic coating are of a porous structure, and the pore diameter is 50-200 nm; nanofibers are uniformly distributed in the first high-molecular polymer matrix layer and the second high-molecular polymer matrix layer, the diameter of the nanofibers is 50-500 nm, and the length of the nanofibers is 1-10 [mu] m; the inorganic solid electrolyte layer is formed by sintering spherical particles with the particle size of 0.5-2 microns, and continuous ion transmission channels are formed among the particles. The solid-state battery diaphragm has high ionic conductivity, excellent mechanical strength and good thermal stability.

Description

Technical Field

[0001] The utility model belongs to the technical field of solid-state batteries, and in particular relates to a solid-state battery separator. Background Art

[0002] Solid-state batteries, due to their high energy density, long cycle life, and excellent safety performance, are considered an important development direction for next-generation energy storage technology. In solid-state batteries, the separator, as a key component, must not only physically isolate the electrodes but also ensure efficient ion transport. However, existing solid-state battery separators still face multiple technical challenges, which restrict the large-scale commercial application of solid-state batteries.

[0003] First, low ionic conductivity is one of the main factors limiting the performance of solid-state batteries. Compared to traditional liquid electrolytes, the ionic conductivity of solid-state electrolytes is typically one to two orders of magnitude lower. This low conductivity not only limits the battery's charge and discharge rates but also reduces its energy density. Researchers have been working to develop new materials and optimize structures to improve ionic conductivity, but currently, it remains elusive to meet the requirements for commercial application.

[0004] Secondly, microcracks caused by insufficient mechanical strength seriously affect the safety and lifespan of solid-state batteries. During the battery's charge and discharge process, the volume changes of the electrode material exert mechanical stress on the solid-state separator. Since most solid-state electrolyte materials are inherently brittle and hard, they are prone to developing microcracks under this repeated stress. These microcracks not only reduce the separator's ionic conductivity but can also cause internal short circuits, posing a serious safety hazard.

[0005] Furthermore, poor stability at high temperatures limits the application of solid-state batteries in extreme environments. Many solid electrolyte materials undergo phase transitions or react adversely with electrode materials at high temperatures, leading to a sharp decline in battery performance or even failure. This problem is particularly prominent in applications such as electric vehicles, which require high temperature adaptability.

[0006] In view of the above problems, the development of a solid-state battery separator with high ionic conductivity, excellent mechanical strength and good thermal stability has become the focus of current research. Utility Model Content

[0007] The purpose of the present invention is to provide a solid-state battery separator with high ionic conductivity, excellent mechanical strength and good thermal stability to address the deficiencies of the existing technology.

[0008] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0009] A solid-state battery separator, comprising an inorganic solid electrolyte layer, a first polymer matrix layer and a second polymer matrix layer respectively disposed on both sides of the inorganic solid electrolyte layer, a first nano-ceramic coating disposed on the outer surface of the first polymer matrix layer, and a second nano-ceramic coating disposed on the outer surface of the second polymer matrix layer;

[0010] The surfaces of the first nano-ceramic coating and the second nano-ceramic coating are porous with a pore size of 50-200 nm;

[0011] Nanofibers are evenly distributed in the first polymer matrix layer and the second polymer matrix layer, wherein the nanofibers have a diameter of 50-500 nm and a length of 1-10 μm;

[0012] The inorganic solid electrolyte layer is formed by sintering spherical particles with a particle size of 0.5-2 μm, and continuous ion transmission channels are formed between the particles.

[0013] Preferably, the nanofibers are polyacrylonitrile nanofibers.

[0014] Preferably, the materials of the first nano-ceramic coating and the second nano-ceramic coating are selected from aluminum oxide nanoparticles, silicon oxide nanoparticles or zirconium oxide nanoparticles. The ceramic nanoparticles have excellent thermal and chemical stability and can effectively improve the heat resistance and corrosion resistance of the diaphragm.

[0015] Preferably, the thickness of the first nano-ceramic coating and the second nano-ceramic coating are both 0.5-1 μm, which provides adequate protection without significantly increasing the total thickness of the diaphragm, thereby facilitating the maintenance of high energy density.

[0016] Preferably, the materials of the first polymer matrix layer and the second polymer matrix layer are selected from polyvinylidene fluoride or polyvinyl alcohol. Both PVDF and PVA have good chemical stability and mechanical properties, and can provide the necessary flexibility and strength for the separator.

[0017] Preferably, the thickness of the first polymer matrix layer and the second polymer matrix layer are both 4-8 μm, thereby providing sufficient mechanical support while maintaining the thinness of the diaphragm.

[0018] Preferably, the material of the inorganic solid electrolyte layer is selected from Li7La3Zr2O 12 (LLZO) or Li 1.3 Al 0.3 Ti 1.7(PO4)3(LATP). Among them, LLZO and LATP are both high-performance solid electrolyte materials with high ionic conductivity and wide electrochemical window, which can significantly improve the ionic conductivity of the separator.

[0019] Preferably, the thickness of the inorganic solid electrolyte layer is 10-15 μm, which ensures high ionic conductivity while controlling the total thickness of the separator, thereby improving the energy density of the battery.

[0020] Preferably, the room temperature ionic conductivity of the solid-state battery separator is ≥1×10 -4 S / cm. This ensures that the separator has excellent ion transport capability, which is beneficial to improving the charge and discharge performance of the battery.

[0021] Preferably, the tensile strength of the solid-state battery separator is ≥100 MPa, ensuring that the separator has sufficient mechanical strength to maintain structural integrity during battery assembly and use.

[0022] Preferably, the heat-resistant temperature of the solid-state battery separator is ≥ 200° C. The high thermal stability of the separator greatly improves the safety of the solid-state battery, enabling it to operate normally in a wider temperature range.

[0023] Compared with the prior art, the beneficial effects of the present invention are: the present invention provides a solid-state battery separator, comprising an inorganic solid electrolyte layer, a first polymer matrix layer and a second polymer matrix layer respectively arranged on the surfaces of both sides of the inorganic solid electrolyte layer, a first nano-ceramic coating arranged on the outer surface of the first polymer matrix layer, and a second nano-ceramic coating arranged on the outer surface of the second polymer matrix layer; wherein, the surface of the first nano-ceramic coating and the second nano-ceramic coating has a porous structure with a pore size of 50-200nm; nanofibers are uniformly distributed in the first polymer matrix layer and the second polymer matrix layer, and the nanofibers have a diameter of 50-500nm and a length of 1-10μm; the inorganic solid electrolyte layer is sintered by spherical particles with a particle size of 0.5-2μm, and continuous ion transmission channels are formed between the particles. The porous structure of the nano-ceramic coating (pore size 50-200nm) increases the contact area with the electrode, improves the interfacial properties, and enhances the mechanical strength and thermal stability of the diaphragm. Furthermore, the uniformly distributed nanofibers (diameter 50-500nm, length 1-10μm) in the polymer matrix enhance the mechanical strength and flexibility of the diaphragm while providing additional ion transport channels. The inorganic solid electrolyte layer is sintered from spherical particles (particle size 0.5-2μm), forming continuous ion transport channels that significantly improve ionic conductivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic structural diagram of the solid-state battery separator of the present invention.

[0025] In the figure: 1. Inorganic solid electrolyte layer; 2. First high molecular polymer matrix layer; 3. Second high molecular polymer matrix layer; 4. First nano-ceramic coating; 5. Second nano-ceramic coating. DETAILED DESCRIPTION

[0026] In order to make the technical solutions and advantages of the present invention clearer, the present invention and its beneficial effects will be described in further detail below in conjunction with specific implementation methods and the accompanying drawings, but the implementation methods of the present invention are not limited thereto.

[0027] Example 1

[0028] like Figure 1 As shown, the present application provides a solid-state battery separator, the structure of which is as follows from top to bottom: a first nano-ceramic coating 4, a first high molecular polymer matrix layer 2, an inorganic solid electrolyte layer 1, a second high molecular polymer matrix layer 3 and a second nano-ceramic coating 5.

[0029] The specific preparation method of the solid-state battery separator is as follows:

[0030] 1) Preparation of nano-ceramic coating: Alumina nanoparticles (particle size 30 nm) were selected as the raw material and dispersed in an ethanol solution and ultrasonically dispersed for 30 minutes. Polyvinylidene fluoride (PVDF) was added as a binder and stirred to obtain a slurry. The slurry was evenly coated on the surface of a polymer substrate by doctor blade coating and dried at 80°C for 2 hours. The dried coating had a thickness of 0.8 μm and a porous structure with pore sizes primarily in the range of 100-150 nm.

[0031] 2) Preparation of the polymer matrix layer: Polyvinylidene fluoride (PVDF) was selected as the matrix material, and a film containing nanofibers was prepared by electrospinning; PVDF was dissolved in N,N-dimethylformamide (DMF) to prepare a 15 wt% solution; at the same time, polyacrylonitrile (PAN) was dissolved in DMF to prepare a 10 wt% solution; the two solutions were mixed in a ratio of 8:2 and spun on an electrospinning device for 30 minutes; the spinning parameters were as follows: voltage 15 kV, propulsion rate 0.5 mL / h, and collection distance 15 cm; the resulting film was vacuum dried at 60°C for 12 hours, with a final thickness of 6 μm; PAN nanofibers with a diameter of approximately 200 nm and a length of 3-5 μm were evenly distributed in the film.

[0032] 3) Preparation of inorganic solid electrolyte layer: Li7La3Zr2O 12(LLZO) was used as an inorganic solid electrolyte material. LLZO powder was synthesized by a solid-phase method. Li2CO3, La2O3, and ZrO2 were mixed in a stoichiometric ratio and ball-milled in a ball mill for 24 hours. The ball-milled powder was calcined at 900°C for 12 hours to obtain an LLZO precursor. The precursor was ball-milled again for 24 hours to screen out spherical particles with a particle size of 0.5-2μm. The screened powder was pressed into a mold and sintered at 1200°C for 8 hours to obtain a dense LLZO solid electrolyte layer with a thickness of 12μm.

[0033] 4) Assembly of the diaphragm: The prepared layers are stacked in sequence and hot pressed at 120°C and 10 MPa pressure for 10 minutes to tightly bond the layers to form an integrated solid-state battery diaphragm.

[0034] Performance test: The room temperature (25°C) ionic conductivity of the solid-state battery separator was measured to be 1.5×10 -4 S / cm, tensile strength is 120MPa, and heat resistance temperature reaches 220℃.

[0035] Example 2

[0036] On the basis of Example 1, the material of the nano-ceramic coating was changed to silicon oxide nanoparticles (particle size 20nm), and the coating thickness was adjusted to 0.6μm; the material of the polymer matrix layer was changed to polyvinyl alcohol (PVA), and the thickness was adjusted to 5μm; the material of the inorganic solid electrolyte layer was changed to Li 1.3 Al 0.3 Ti 1.7 (PO4)3(LATP), the thickness was adjusted to 14 μm.

[0037] The specific preparation method of the diaphragm is similar to that of Example 1, and the preparation parameters of each layer are adjusted as follows:

[0038] 1) Nano-ceramic coating: Silicon oxide nanoparticles were dispersed in isopropyl alcohol and ultrasonicated for 40 minutes; the drying temperature was adjusted to 90° C. and the drying time was 1.5 hours.

[0039] 2) Polymer matrix layer: PVA was dissolved in water to prepare a 12 wt % solution; electrospinning parameters: voltage 18 kV, propulsion rate 0.8 mL / h, collection distance 18 cm.

[0040] 3) Inorganic solid electrolyte layer: LATP powder was prepared by sol-gel method, and the precursor was calcined at 850°C for 10 hours; the final sintering temperature was 1000°C and the time was 10 hours.

[0041] 4) Diaphragm assembly: The hot pressing temperature was adjusted to 100°C, the pressure was 15 MPa, and the time was 15 minutes.

[0042] Performance test: The room temperature (25°C) ionic conductivity of the solid-state battery separator was measured to be 1.8×10 -4 S / cm, tensile strength is 110MPa, and heat resistance temperature reaches 210℃.

[0043] Based on the disclosure and teachings of the above description, those skilled in the art will be able to make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments described above. Any obvious improvements, substitutions, or modifications made by those skilled in the art based on the present invention fall within the scope of protection of the present invention. In addition, although certain specific terms are used in this description, these terms are for convenience only and do not constitute any limitation on the present invention.

Claims

1. A solid-state battery separator, characterized in that: The invention comprises an inorganic solid electrolyte layer, a first high molecular polymer matrix layer and a second high molecular polymer matrix layer respectively arranged on both sides of the inorganic solid electrolyte layer, a first nano-ceramic coating arranged on the outer surface of the first high molecular polymer matrix layer, and a second nano-ceramic coating arranged on the outer surface of the second high molecular polymer matrix layer; The surfaces of the first nano-ceramic coating and the second nano-ceramic coating are porous with a pore size of 50-200 nm; Nanofibers are evenly distributed in the first polymer matrix layer and the second polymer matrix layer, wherein the nanofibers have a diameter of 50-500 nm and a length of 1-10 μm; The inorganic solid electrolyte layer is formed by sintering spherical particles with a particle size of 0.5-2 μm, and continuous ion transmission channels are formed between the particles.

2. The solid-state battery separator according to claim 1, characterized in that: The materials of the first nano-ceramic coating and the second nano-ceramic coating are selected from aluminum oxide nanoparticles, silicon oxide nanoparticles or zirconium oxide nanoparticles.

3. The solid-state battery separator according to claim 1, characterized in that: The thickness of the first nano-ceramic coating and the second nano-ceramic coating are both 0.5-1 μm.

4. The solid-state battery separator according to claim 1, characterized in that: The materials of the first polymer matrix layer and the second polymer matrix layer are selected from polyvinylidene fluoride or polyvinyl alcohol.

5. The solid-state battery separator according to claim 1, characterized in that: The thickness of the first high molecular polymer matrix layer and the second high molecular polymer matrix layer are both 4-8 μm.

6. The solid-state battery separator according to claim 1, characterized in that: The material of the inorganic solid electrolyte layer is selected from LLZO or LATP.

7. The solid-state battery separator according to claim 1, characterized in that: The thickness of the inorganic solid electrolyte layer is 10-15 μm.

8. The solid-state battery separator according to claim 1, characterized in that: The room temperature ionic conductivity of the solid-state battery separator is ≥1×10 -4 S / cm.

9. The solid-state battery separator according to claim 1, characterized in that: The tensile strength of the solid-state battery separator is ≥100 MPa.

10. The solid-state battery separator according to claim 1, characterized in that: The heat-resistant temperature of the solid-state battery separator is ≥200°C.

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