High-temperature-resistant and anti-shrinkage sodium battery diaphragm

Abstract

The utility model discloses a high-temperature-resistant and anti-shrinkage sodium battery diaphragm which comprises a base diaphragm, the first temperature-resistant ceramic coating is arranged in the middle of the surface of at least one side of the base film; the second temperature-resistant ceramic coating is arranged on the peripheral edge of the surface of at least one side of the base film and tightly surrounds the periphery of the first temperature-resistant ceramic coating; wherein the compaction density of the second temperature-resistant ceramic coating is greater than that of the first temperature-resistant ceramic coating; the compaction density of the first temperature-resistant ceramic coating is 0.8 g / cm < 3 > to 1.5 g / cm < 3 >, and the compaction density of the second temperature-resistant ceramic coating is 1.0 g / cm < 3 > to 2.0 g / cm < 3 >; wherein the heat-resistant temperature of the diaphragm is greater than or equal to 200 DEG C. Compared with the prior art, the first temperature-resistant ceramic coating and the second temperature-resistant ceramic coating with different compaction densities are arranged on the base membrane, so that the high temperature resistance and the shrinkage resistance of the sodium battery diaphragm are remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of sodium-ion battery technology, and particularly relates to a high-temperature resistant and shrink-resistant sodium battery separator. Background Technology

[0002] With the adjustment of the energy structure and the continuous expansion of renewable energy utilization, sodium batteries, as an electrochemical energy storage device with abundant resources, relatively low cost, and potential energy density advantages, are gradually attracting industry attention. However, to ensure the high performance and long lifespan of sodium batteries, the separator, as a key component, plays a crucial role in the overall performance of the battery due to its material and structural characteristics.

[0003] Most existing sodium battery separators use polyolefin materials (such as polyethylene and polypropylene) or other polymer films. These separators possess a certain degree of ion permeability and mechanical strength at room temperature, meeting some application requirements. However, in higher temperature environments (such as high-power charging and discharging, and continuous operation under harsh conditions), traditional separators are prone to softening, melting, or deformation. This leads to changes in the separator's pore structure, impaired ion transport, and ultimately, increased internal resistance, battery capacity decay, and even safety hazards. Furthermore, significant shrinkage of the separator at high temperatures alters the electrode spacing, increasing the risk of localized short circuits.

[0004] Therefore, there is an urgent need to provide a technical solution to the above problems. Utility Model Content

[0005] The purpose of this invention is to provide a high-temperature resistant and shrink-resistant sodium battery separator to address the shortcomings of existing technologies, thereby solving the problems of insufficient high-temperature resistance and poor shrink-resistant performance of existing sodium battery separators.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A high-temperature resistant and shrink-resistant sodium battery separator, comprising:

[0008] Base film;

[0009] A first heat-resistant ceramic coating is disposed in the middle of at least one side surface of the base film;

[0010] The second heat-resistant ceramic coating is disposed on the periphery of at least one side surface of the base film and is closely surrounding the periphery of the first heat-resistant ceramic coating;

[0011] The compaction density of the second heat-resistant ceramic coating is greater than that of the first heat-resistant ceramic coating; the compaction density of the first heat-resistant ceramic coating is 0.8 g / cm³. 3 ~1.5g / cm 3The compaction density of the second heat-resistant ceramic coating is 1.0 g / cm³. 3 ~2.0g / cm 3 ;

[0012] The heat resistance temperature of the diaphragm is ≥200℃.

[0013] Furthermore, the compaction density of the second heat-resistant ceramic coating is more than 20% higher than that of the first heat-resistant ceramic coating.

[0014] Furthermore, the base film is formed by a biaxial stretching process and has a pore structure with uniformly distributed pores in both the longitudinal and transverse directions. The pore size ranges from 0.05 to 0.2 μm, and the porosity is from 40% to 60%.

[0015] Furthermore, the base film is a PI film or a PEEK film.

[0016] Furthermore, the thickness of the base film is 10–15 μm.

[0017] Furthermore, the thickness of the second heat-resistant ceramic coating is greater than the thickness of the first heat-resistant ceramic coating;

[0018] And / or, the thickness of the first heat-resistant ceramic coating is 2 to 5 μm, and the thickness of the second heat-resistant ceramic coating is 3 to 6 μm.

[0019] Furthermore, both the first and second high-temperature resistant ceramic coatings comprise ceramic particles and a binder. The ceramic particles are selected from silicon oxide, zirconium oxide, alumina, or silicon nitride, and the binder is polyvinylidene fluoride (PVDF). The particle size range of the ceramic particles is 0.1–0.5 μm.

[0020] Furthermore, after the diaphragm is heat-treated at 150°C to 200°C, the dimensional change rate of the diaphragm does not exceed 3%.

[0021] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0022] 1) The separator provided by this utility model can have a heat resistance temperature of ≥200℃ by setting a first heat-resistant ceramic coating and a second heat-resistant ceramic coating on the surface of the base membrane, which is significantly higher than the heat resistance performance of traditional sodium battery separators. This ensures that the separator can still work stably under high temperature conditions, prevents the separator from softening, melting or failing, thereby improving the safety and reliability of sodium batteries in high temperature environments.

[0023] 2) The first heat-resistant ceramic coating of this invention is disposed in the middle of the base membrane, providing basic heat-resistant protection for the central area; the second heat-resistant ceramic coating closely surrounds the perimeter of the first coating, forming a double-layer protective structure. This arrangement not only improves the overall heat resistance of the diaphragm, but also prevents local stress concentration caused by thermal expansion or contraction by strengthening the support of the edge area, further enhancing the structural stability of the diaphragm. Furthermore, the compaction density of the second heat-resistant ceramic coating (1.0 g / cm³) is... 3 ~2.0g / cm 3 The value is greater than that of the first high-temperature resistant ceramic coating (0.8 g / cm³). 3 ~1.5g / cm 3 This gradient compaction density design effectively enhances the mechanical strength and dimensional stability of the separator edge area, prevents edge area warping or shrinkage under high temperature conditions, ensures the integrity of the overall separator structure, and reduces the risk of short circuits in the battery. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of a sodium battery separator in one embodiment of the present invention.

[0025] In the figure: 1. Base film; 2. First high-temperature resistant ceramic coating; 3. Second high-temperature resistant ceramic coating. Detailed Implementation

[0026] To make the technical solution and advantages of this utility model clearer, the present utility model and its beneficial effects will be described in further detail below with reference to specific embodiments and accompanying drawings. However, the embodiments of this utility model are not limited thereto.

[0027] like Figure 1 As shown, this application provides a high-temperature resistant and shrink-resistant sodium battery separator, comprising:

[0028] Base film 1;

[0029] A first heat-resistant ceramic coating 2 is disposed in the middle of at least one side surface of the base film 1;

[0030] The second heat-resistant ceramic coating 3 is disposed on the periphery of at least one side surface of the base film 1 and is closely surrounding the periphery of the first heat-resistant ceramic coating 2;

[0031] The compaction density of the second heat-resistant ceramic coating 3 is greater than that of the first heat-resistant ceramic coating 2; the compaction density of the first heat-resistant ceramic coating 2 is 0.8 g / cm³. 3 ~1.5g / cm 3 The compaction density of the second heat-resistant ceramic coating 3 is 1.0 g / cm³. 3 ~2.0g / cm 3 ;

[0032] The heat resistance temperature of the diaphragm is ≥200℃.

[0033] The high-temperature resistant and shrink-resistant sodium battery separator provided in this application has the following advantages:

[0034] 1) Improved high temperature resistance: The heat resistance temperature of the separator in this application is ≥200℃, which is significantly higher than that of traditional sodium battery separators. This ensures that the separator can still work stably under high temperature conditions, preventing the separator from softening, melting or failing, thereby improving the safety and reliability of sodium batteries in high temperature environments.

[0035] 2) Optimized anti-shrinkage performance: The compaction density of the second heat-resistant ceramic coating 3 in this application is 1.0 g / cm³. 3 ~2.0g / cm 3 Greater than the first high-temperature resistant ceramic coating 2 (0.8 g / cm³) 3 ~1.5g / cm 3 This gradient compaction density design effectively enhances the mechanical strength and dimensional stability of the separator edge area, prevents edge area warping or shrinkage under high temperature conditions, ensures the integrity of the overall separator structure, and reduces the risk of short circuits in the battery.

[0036] 3) Enhanced structural stability: The first temperature-resistant ceramic coating 2 of this application is disposed in the middle of the base membrane 1, providing basic temperature-resistant protection for the central area; the second temperature-resistant ceramic coating 3 closely surrounds the periphery of the first coating, forming a double-layer protective structure; this layout not only improves the overall temperature resistance of the diaphragm, but also prevents local stress concentration caused by thermal expansion or contraction by strengthening the support of the edge area, thereby further improving the structural stability of the diaphragm.

[0037] In one embodiment of this application, the compaction density of the second heat-resistant ceramic coating is more than 20% higher than that of the first heat-resistant ceramic coating. This compaction density design, while ensuring ion conductivity, enhances the resistance to thermal shrinkage in the edge region through the high compaction density coating, maintaining a stable edge shape and avoiding warping or peeling caused by stress concentration under high-temperature conditions. The formation of the compaction density gradient further optimizes the thermodynamic properties of the diaphragm, satisfying the ion permeability requirements of the central region while improving the edge's resistance to deformation.

[0038] In one embodiment of this application, the base film 1 is formed by a biaxial stretching process, having a pore structure with uniform longitudinal and transverse distribution. The pore size ranges from 0.05 to 0.2 μm, and the porosity is from 40% to 60%. The biaxial stretching process endows the base film 1 with high mechanical strength and dimensional stability, enabling it to withstand high temperature and high pressure conditions. The rationally designed pore structure optimizes the ion conduction path while reducing the risk of pore collapse and structural failure, further improving the overall performance of the battery.

[0039] In one embodiment of this application, the base membrane 1 is a PI membrane or a PEEK membrane. Both polyimide (PI) and polyetheretherketone (PEEK) are high-temperature resistant polymer materials with extremely high heat resistance and mechanical strength, ensuring that the membrane maintains stable performance even at temperatures above 200°C.

[0040] In one embodiment according to this application, the thickness of the base film 1 is 10–15 μm. This thickness range is designed to ensure mechanical strength while avoiding increased ion conduction resistance caused by excessive thickness, thus balancing strength and conductivity.

[0041] In one embodiment according to this application, the thickness of the second heat-resistant ceramic coating 3 is greater than the thickness of the first heat-resistant ceramic coating 2;

[0042] And / or, the thickness of the first heat-resistant ceramic coating 2 is 2 to 5 μm, and the thickness of the second heat-resistant ceramic coating 3 is 3 to 6 μm.

[0043] The design of the coating thickness gradient allows the first coating in the central region to maintain high ion permeability, while the second coating in the edge region further enhances its resistance to mechanical deformation by increasing its thickness.

[0044] In one embodiment of this application, both the first high-temperature resistant ceramic coating 2 and the second high-temperature resistant ceramic coating 3 comprise ceramic particles and a binder. The ceramic particles are selected from silicon oxide, zirconium oxide, alumina, or silicon nitride, and the binder is polyvinylidene fluoride (PVDF). The particle size range of the ceramic particles is 0.1–0.5 μm. The high melting point and low thermal expansion characteristics of the ceramic particles significantly enhance the high-temperature resistance of the membrane, while the PVDF binder provides excellent mechanical stability and flexibility. The selection of the particle size range ensures the uniformity of the coating and optimized pore distribution, improving overall ion permeability.

[0045] In one embodiment according to this application, after heat treatment of the separator at 150°C to 200°C, the dimensional change rate of the separator does not exceed 3%. This indicates that the separator can maintain structural stability and functional integrity even at extreme high temperatures, reducing the risk of internal short circuits in the battery.

[0046] Based on the disclosure and teachings of the above specification, those skilled in the art can make changes and modifications to the above embodiments. Therefore, this utility model is not limited to the specific embodiments described above, and any obvious improvements, substitutions, or modifications made by those skilled in the art based on this utility model are within the protection scope of this utility model. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on this utility model.

Claims

1. A high-temperature resistant and shrink-resistant sodium battery separator, characterized in that, include: Base film; A first heat-resistant ceramic coating is disposed in the middle of at least one side surface of the base film; The second heat-resistant ceramic coating is disposed on the periphery of at least one side surface of the base film and is closely surrounding the periphery of the first heat-resistant ceramic coating; The compaction density of the second heat-resistant ceramic coating is greater than that of the first heat-resistant ceramic coating; the compaction density of the first heat-resistant ceramic coating is 0.8 g / cm³. 3 ~1.5g / cm 3 The compaction density of the second heat-resistant ceramic coating is 1.0 g / cm³. 3 ~2.0g / cm 3 ; The heat resistance temperature of the diaphragm is ≥200℃.

2. The high-temperature resistant and shrink-resistant sodium battery separator according to claim 1, characterized in that: The compaction density of the second heat-resistant ceramic coating is more than 20% higher than that of the first heat-resistant ceramic coating.

3. The high-temperature resistant and shrink-resistant sodium battery separator according to claim 1, characterized in that: The base film is formed by a biaxial stretching process and has a pore structure with uniformly distributed pores in both the longitudinal and transverse directions. The pore size ranges from 0.05 to 0.2 μm and the porosity is from 40% to 60%.

4. The high-temperature resistant and shrink-resistant sodium battery separator according to claim 1, characterized in that: The base film is a PI film or a PEEK film.

5. The high-temperature resistant and shrink-resistant sodium battery separator according to claim 1, characterized in that: The thickness of the base film is 10–15 μm.

6. The high-temperature resistant and shrink-resistant sodium battery separator according to claim 1, characterized in that: The thickness of the second heat-resistant ceramic coating is greater than the thickness of the first heat-resistant ceramic coating; And / or, the thickness of the first heat-resistant ceramic coating is 2 to 5 μm, and the thickness of the second heat-resistant ceramic coating is 3 to 6 μm.

7. The high-temperature resistant and shrink-resistant sodium battery separator according to claim 1, characterized in that: The ceramic particles in the first and second heat-resistant ceramic coatings are all made of silicon oxide, zirconium oxide, aluminum oxide, or silicon nitride; the particle size range of the ceramic particles is 0.1 to 0.5 μm.

8. The high-temperature resistant and shrink-resistant sodium battery separator according to claim 1, characterized in that: After the diaphragm is heat-treated at 150℃ to 200℃, the dimensional change rate of the diaphragm does not exceed 3%.

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