Ferroelectric material film composite sodium metal negative electrode and preparation method and application thereof

Abstract

The invention provides a ferroelectric material film composite sodium metal negative electrode and a preparation method and application thereof, and belongs to the technical field of sodium batteries. The ferroelectric material film composite sodium metal negative electrode comprises a sodium metal substrate and a ferroelectric material film layer, the ferroelectric material film layer tightly covers the surface of the sodium metal matrix in a physical coating mode, and a ferroelectric material in the ferroelectric material film layer is selected from at least one of barium titanate, lead zirconate titanate, potassium sodium niobate and hafnium zirconium oxide. According to the invention, the spontaneous polarization electric field characteristic of the ferroelectric material is combined, the ferroelectric material acts on the surface of the sodium metal to serve as a protective layer, and the migration rate of sodium ions is greatly increased and the polarization overpotential is greatly reduced due to the fact that electric dipoles in the film are orderly arranged to generate a built-in electric field in battery circulation. The ferroelectric material film has good mechanical strength, can protect sodium metal from being corroded by organic electrolyte, and effectively improves the cycle stability of the battery.

Description

Technical Field

[0001] This invention belongs to the field of sodium battery technology, and particularly relates to a ferroelectric material thin film composite sodium metal anode, its preparation method and application. Background Technology

[0002] Lithium-ion batteries, due to their high energy density, long cycle life, and good environmental adaptability, have been widely used in new energy vehicles, portable electronic devices, and large-scale energy storage systems. However, the limited and uneven distribution of global lithium resources has led to a continuous increase in their cost, hindering the sustainable development of the lithium battery industry. In contrast, sodium resources are abundant and widely distributed, and sodium-ion batteries share similar working principles and electrochemical characteristics with lithium-ion batteries, thus demonstrating significant substitution potential in areas such as large-scale energy storage.

[0003] In sodium-ion battery systems, sodium metal anodes are considered one of the most attractive anode materials due to their extremely high theoretical specific capacity (approximately 1166 mAh / g) and low redox potential (approximately -2.73 V vs. SHE). However, sodium metal still faces many challenges in practical applications: In conventional organic liquid electrolytes, sodium metal spontaneously reacts with the electrolyte to form a complex and structurally heterogeneous solid electrolyte interface (SEI) film. This in-situ formed SEI film has low mechanical strength and uneven ionic conductivity, making it prone to cracking due to volume changes during sodium deposition / stripping. The cracks become active sites for sodium dendrite growth, leading to internal short circuits, capacity decay, and safety hazards within the battery.

[0004] To suppress dendrite growth and improve interfacial stability, researchers have attempted to construct artificial protective layers on the surface of sodium metal. For example, existing technologies use materials such as indium vanadate (InVO4) to react with sodium metal, forming a Na-In-VO compound interfacial layer (as described in patent publication CN116885106A), which improves deposition behavior by providing uniform sodium ion deposition sites. However, this type of method still has the following shortcomings:

[0005] (1) The interface layer is formed through a chemical reaction, which consumes the active sodium source and reduces the overall energy density of the battery;

[0006] (2) The reaction process is accompanied by volume changes, which can easily cause interfacial cracking during cycling;

[0007] (3) Film formation requires a long reaction time (usually 12-24 hours), resulting in low process efficiency and hindering large-scale production;

[0008] (4) Its mechanism of action is still passive regulation, and its ability to calibrate the kinetics of sodium ion transport is limited.

[0009] Therefore, constructing an artificial interface layer that does not consume sodium sources, has a stable structure, and possesses the ability to actively guide sodium ion transport has become crucial for improving the performance of sodium metal anodes. Ferroelectric materials, due to their unique spontaneous polarization characteristics, can form an ordered electric field internally, potentially providing a directional driving force for sodium ion migration, thereby enabling active control over deposition behavior. However, there is currently no systematic research on constructing ferroelectric materials on sodium metal surfaces using physical coating and applying them to sodium-ion batteries. Therefore, developing a ferroelectric composite sodium metal anode with a simple process, stable interface, and the ability to actively guide the orderly deposition of sodium ions is of great significance for promoting the development of high-safety, long-life sodium metal batteries. Summary of the Invention

[0010] To address the technical problems in existing technologies where the SEI film formed by sodium metal anode has low mechanical strength, slow sodium ion migration rate, sodium source consumption, and volume expansion during SEI film construction, leading to uncontrollable sodium dendrite growth and decreased battery cycle performance, this invention proposes a ferroelectric material thin film composite sodium metal anode, its preparation method, and its application.

[0011] To achieve the above objectives, the present invention provides the following technical solution:

[0012] This invention proposes a ferroelectric material thin film composite sodium metal anode, comprising a sodium metal substrate and a ferroelectric material thin film layer; the ferroelectric material thin film layer is tightly coated on the surface of the sodium metal substrate by physical coating, and the ferroelectric material in the ferroelectric material thin film layer is selected from at least one of barium titanate, lead zirconate titanate, potassium sodium niobate and hafnium zirconium oxide.

[0013] Furthermore, the loading of the ferroelectric material thin film layer on the sodium metal substrate is 1 mg / cm³. 2 .

[0014] Furthermore, the thickness of the sodium metal matrix is ​​200–400 μm.

[0015] This invention also proposes a method for preparing the above-mentioned ferroelectric material thin film composite sodium metal anode, comprising the following steps:

[0016] (1) In an inert atmosphere glove box, sodium metal blocks are made into sodium metal sheets;

[0017] (2) The ferroelectric material powder was ball-milled to obtain fine powder with a particle size of 0.5 to 1 μm;

[0018] (3) The ferroelectric material powder is uniformly coated on the surface of the sodium metal sheet and then physically pressed to make it adhere tightly to form a ferroelectric material thin film layer, thereby obtaining the ferroelectric material thin film composite sodium metal anode.

[0019] Furthermore, the ball milling process is carried out at a rotation speed of 1400 r / min for 1 hour.

[0020] Furthermore, the coating time is 0.5 to 1 hour.

[0021] Furthermore, both steps (1) and (3) are carried out under an argon atmosphere, and the water and oxygen content is less than 0.01 ppm.

[0022] The present invention also proposes the application of the above-mentioned ferroelectric material thin film composite sodium metal anode in sodium-ion batteries.

[0023] Furthermore, the sodium-ion battery includes an electrolyte, a separator, a positive electrode, and the aforementioned ferroelectric material thin film composite sodium metal negative electrode. The electrolyte is obtained by dissolving NaPF6 in dimethyl ethylene glycol (DME).

[0024] Compared with the prior art, the present invention has the following advantages and technical effects:

[0025] This invention leverages the spontaneous polarization electric field characteristics of ferroelectric materials, applying them as a protective layer to the surface of sodium metal. During battery cycling, the ordered arrangement of electric dipoles within the film generates an internal electric field, significantly increasing the migration rate of sodium ions and substantially reducing polarization overpotential. The ferroelectric material film in this invention possesses excellent mechanical strength while simultaneously protecting the sodium metal from corrosion by organic electrolytes, effectively improving the battery's cycle stability.

[0026] The method for preparing the ferroelectric material thin film composite sodium metal anode of the present invention is simple and can be obtained by coating. The operation does not rely on large-scale precision equipment, the process is simple and easy to operate, and it has the potential for large-scale application. Attached Figure Description

[0027] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0028] Figure 1 The X-ray diffraction pattern of the ferroelectric material thin film composite sodium metal anode prepared in Example 1 of this invention;

[0029] Figure 2 The scanning electron microscope image and elemental distribution map of the ferroelectric material thin film composite sodium metal anode prepared in Example 1 of this invention;

[0030] Figure 3 A symmetrical battery assembled from the ferroelectric material thin film composite sodium metal anode (BaTiO3 / Na) of Example 1 and the sodium metal sheet (Bare Na) of Comparative Example 1, at 1 mA·cm -21mAh·cm -2 Voltage-time curves under the given conditions. Detailed Implementation

[0031] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0032] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0033] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0034] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This specification and embodiments are merely exemplary.

[0035] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0036] This invention provides a ferroelectric material thin film composite sodium metal anode, comprising a sodium metal substrate and a ferroelectric material thin film layer; the ferroelectric material thin film layer is tightly coated on the surface of the sodium metal substrate by physical coating, and the ferroelectric material in the ferroelectric material thin film layer is selected from at least one of barium titanate, lead zirconate titanate, potassium sodium niobate and hafnium zirconium oxide.

[0037] In a preferred embodiment of the present invention, the loading of the ferroelectric material thin film layer on the sodium metal substrate is 1 mg / cm². 2 .

[0038] In a preferred embodiment of the present invention, the thickness of the sodium metal matrix is ​​200–400 μm.

[0039] Existing technologies use indium vanadate (InVO4) to react with sodium metal to form a Na-In-VO compound interface layer, relying on chemically active sites to guide sodium ion deposition. This invention uses ferroelectric materials (such as barium titanate, lead zirconate titanate, etc.) to actively guide the orderly transport of sodium ions through their spontaneous polarization electric field, upgrading from passive regulation to active guidance, which significantly improves the sodium ion migration rate and deposition uniformity.

[0040] This invention also proposes a method for preparing the above-mentioned ferroelectric material thin film composite sodium metal anode, comprising the following steps:

[0041] (1) In an inert atmosphere glove box, sodium metal blocks are made into sodium metal sheets;

[0042] (2) The ferroelectric material powder was ball-milled to obtain fine powder with a particle size of 0.5 to 1 μm;

[0043] (3) The ferroelectric material powder is uniformly coated on the surface of the sodium metal sheet and then physically pressed to make it adhere tightly to form a ferroelectric material thin film layer, thus obtaining a ferroelectric material thin film composite sodium metal anode.

[0044] In a preferred embodiment of the present invention, the ball milling speed is 1400 r / min and the ball milling time is 1 hour.

[0045] In a preferred embodiment of the present invention, the coating time is 0.5 to 1 hour.

[0046] In a preferred embodiment of the present invention, steps (1) and (3) are both carried out under an argon atmosphere, and the water and oxygen content is less than 0.01 ppm.

[0047] Existing technologies use a chemically generated interface layer, which consumes sodium metal and may cause volume changes. This invention forms a stable ferroelectric material film through physical coating, avoiding chemical reactions with sodium metal and the consumption of sodium sources, thus preventing volume expansion and structural instability caused by interface reactions. Furthermore, this invention achieves film formation solely through ball milling, physical coating, and pressing, eliminating the need for chemical reactions and significantly reducing processing time, making it more suitable for continuous, large-scale production.

[0048] The present invention also proposes an application of the above-mentioned ferroelectric material thin film composite sodium metal anode in sodium-ion batteries.

[0049] In a preferred embodiment of the present invention, the sodium-ion battery includes an electrolyte, a separator, a positive electrode, and the above-mentioned ferroelectric material thin film composite sodium metal negative electrode. The electrolyte is obtained by dissolving NaPF6 in dimethyl ethylene glycol (DME) with a concentration of 1M.

[0050] All raw materials used in the embodiments of this invention were purchased commercially.

[0051] The technical solution of the present invention will be further illustrated by the following embodiments.

[0052] Example 1

[0053] A method for preparing a ferroelectric material thin film composite sodium metal anode includes the following steps:

[0054] (1) In an inert atmosphere glove box, the sodium metal, which was protected by kerosene, was removed and the surface oxide layer was removed. The sodium metal was then rolled into a sheet with an area of ​​100 cm² using a roller press. 2 A sodium metal sheet with a thickness of 200 μm;

[0055] (2) Pour barium titanate powder into a ball mill and ball mill the barium titanate powder at 1400 r / min for 1 hour to obtain barium titanate powder with a particle size of 0.5~1µm;

[0056] (3) In an inert atmosphere glove box, ball-milled barium titanate powder was uniformly coated onto the sodium metal surface, with a barium titanate loading of 1 mg·cm³. -2 Then, the powder was gently pressed and repeatedly applied for 30 minutes. After the barium titanate powder and the soft sodium metal sheet came into close contact, a ferroelectric material thin film composite sodium metal anode (BaTiO3 / Na) was obtained. The protective gas in the glove box was argon, and the contents of water and oxygen were both less than 0.01 ppm.

[0057] Example 2

[0058] A method for preparing a ferroelectric material thin film composite sodium metal anode includes the following steps:

[0059] (1) In an inert atmosphere glove box, the sodium metal, which was protected by kerosene, was removed and the surface oxide layer was removed. The sodium metal was then rolled into a sheet with an area of ​​100 cm² using a roller press. 2 A sodium metal sheet with a thickness of 200 μm;

[0060] (2) Pour the lead zirconate titanate powder into a ball mill and ball mill the lead zirconate titanate powder at 1400 r / min for 1 hour to obtain lead zirconate titanate powder with a particle size of 0.5~1µm;

[0061] (3) In an inert atmosphere glove box, ball-milled lead zirconate titanate powder was uniformly coated onto the sodium metal surface, with a lead zirconate titanate loading of 1 mg·cm⁻¹. -2Then, the powder was gently pressed and repeatedly applied for 30 minutes. After the lead zirconate titanate powder and the soft sodium metal sheet came into close contact, a ferroelectric material thin film composite sodium metal anode was obtained. The protective gas in the glove box was argon, and the contents of water and oxygen were both less than 0.01 ppm.

[0062] Example 3

[0063] A method for preparing a ferroelectric material thin film composite sodium metal anode includes the following steps:

[0064] (1) In an inert atmosphere glove box, the sodium metal, which was protected by kerosene, was removed and the surface oxide layer was removed. The sodium metal was then rolled into a sheet with an area of ​​100 cm² using a roller press. 2 A sodium metal sheet with a thickness of 200 μm;

[0065] (2) Pour the potassium sodium niobate powder into a ball mill and ball mill the potassium sodium niobate powder at 1400 r / min for 1 hour to obtain potassium sodium niobate powder with a particle size of 0.5~1µm;

[0066] (3) In an inert atmosphere glove box, ball-milled potassium sodium niobate powder was uniformly coated onto the sodium metal surface, with a potassium sodium niobate loading of 1 mg·cm⁻¹. -2 Then, the powder was gently pressed and repeatedly applied for 30 minutes. After the potassium sodium niobate powder and the soft sodium metal sheet came into close contact, a ferroelectric material thin film composite sodium metal anode was obtained. The protective gas in the glove box was argon, and the contents of water and oxygen were both less than 0.01 ppm.

[0067] Example 4

[0068] A method for preparing a ferroelectric material thin film composite sodium metal anode includes the following steps:

[0069] (1) In an inert atmosphere glove box, sodium metal protected by kerosene is removed and its surface oxide layer is removed. The sodium metal is then rolled into a sheet with an area of ​​100 cm² using a roller press. 2 A sodium metal sheet with a thickness of 200 μm;

[0070] (2) Hf 0.5 Zr 0.5 O2 powder was poured into a ball mill, and hafnium zirconium oxide powder was ball milled at 1400 r / min for 1 hour to obtain hafnium zirconium oxide powder with a particle size of 0.5~1µm.

[0071] (3) In an inert atmosphere glove box, ball-milled hafnium zirconium oxide powder was uniformly coated onto the surface of sodium metal, with a hafnium zirconium oxide loading of 1 mg·cm³. -2Then, the powder was gently pressed and repeatedly applied for 30 minutes. After the hafnium zirconium oxide powder and the soft sodium metal sheet came into close contact, a ferroelectric material thin film composite sodium metal anode was obtained. The protective gas in the glove box was argon, and the contents of water and oxygen were both less than 0.01 ppm.

[0072] Comparative Example 1

[0073] In an inert atmosphere glove box, sodium metal protected by kerosene is removed and its surface oxide layer is scraped off. The sodium metal is then rolled into a 100 cm² sheet using a roller press. 2 A 200μm thick sheet of sodium metal (Bare Na).

[0074] Performance testing

[0075] The X-ray diffraction pattern of the ferroelectric material thin film composite sodium metal anode prepared in Example 1 of this invention is shown in Figure 1. Figure 1 Scanning electron microscope images and elemental distribution maps are shown below. Figure 2 .

[0076] from Figure 1-2 It can be seen that the ferroelectric material thin film composite sodium metal anode prepared in Example 1 of this invention exhibits diffraction peaks of barium titanate. Further scanning electron microscopy and elemental analysis of the barium titanate thin film composite sodium metal anode show that the elemental distribution on the surface of the barium titanate thin film composite sodium metal anode is that Ba, Ti, and O elements are uniformly distributed on the sodium metal surface, indicating that a BaTiO3 thin film was successfully constructed artificially on the sodium metal surface.

[0077] The ferroelectric material thin film composite sodium metal anode (BaTiO3 / Na) prepared in Example 1 or the sodium metal sheet (Bare Na) in Comparative Example 1 were assembled into a symmetrical cell. The assembled symmetrical cell was then subjected to a current density of 1 mA·cm⁻¹. -2 The surface capacity is 1mAh·cm³. -2 Constant current charge-discharge tests were conducted under the specified conditions. The electrolyte used was prepared by dissolving NaPF6 in dimethyl glycol ether (DME) at a concentration of 1 M. Performance test results are as follows: Figure 3 As shown, the overpotential of the symmetric battery assembled with a sodium metal sheet (Bare Na) is as high as 20 mV, and a micro-short circuit occurs only after approximately 130 hours of stable cycling. The symmetric battery assembled with BaTiO3 / Na prepared by the method provided in Example 1 of this invention has an overpotential reduced to approximately 9 mV and a cycle life extended to over 700 hours. This indicates that the artificial BaTiO3 interface film constructed from the barium titanate film composite sodium metal anode provided by this invention enhances sodium ion transport kinetics, significantly reduces polarization overpotential, and effectively improves battery cycle stability.

[0078] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A ferroelectric material thin-film composite sodium metal anode, characterized in that, It includes a sodium metal substrate and a ferroelectric material thin film layer; the ferroelectric material thin film layer is tightly covered on the surface of the sodium metal substrate by physical coating, and the ferroelectric material in the ferroelectric material thin film layer is selected from at least one of barium titanate, lead zirconate titanate, potassium sodium niobate and hafnium zirconium oxide.

2. The ferroelectric material thin film composite sodium metal anode according to claim 1, characterized in that, The loading of the ferroelectric material thin film layer on the sodium metal substrate is 1 mg / cm². 2 .

3. The ferroelectric material thin film composite sodium metal anode according to claim 1, characterized in that, The thickness of the sodium metal matrix is ​​200–400 μm.

4. A method for preparing a ferroelectric material thin film composite sodium metal anode as described in any one of claims 1 to 3, characterized in that, Includes the following steps: (1) In an inert atmosphere glove box, sodium metal blocks are made into sodium metal sheets; (2) The ferroelectric material powder was ball-milled to obtain fine powder with a particle size of 0.5 to 1 μm; (3) The fine powder is uniformly coated on the surface of the sodium metal sheet and then physically pressed to make it adhere tightly to form a ferroelectric material thin film layer, thereby obtaining the ferroelectric material thin film composite sodium metal anode.

5. The preparation method according to claim 4, characterized in that, The ball milling process was carried out at a speed of 1400 r / min for 1 hour.

6. The preparation method according to claim 4, characterized in that, The coating process takes 0.5 to 1 hour.

7. The preparation method according to claim 4, characterized in that, Both steps (1) and (3) were carried out under an argon atmosphere, and the water and oxygen content was less than 0.01 ppm.

8. The application of a ferroelectric material thin film composite sodium metal anode as described in any one of claims 1 to 3 in a sodium-ion battery.

9. The application of the ferroelectric material thin film composite sodium metal anode according to claim 8 in sodium-ion batteries, characterized in that, The sodium-ion battery includes an electrolyte, a separator, a positive electrode, and a ferroelectric material thin film composite sodium metal negative electrode as described in any one of claims 1 to 3.

10. The application of the ferroelectric material thin film composite sodium metal anode according to claim 8 in sodium-ion batteries, characterized in that, The electrolyte is a NaPF6 ethylene glycol dimethyl ether solution.

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