Puncture-resistant sodium battery diaphragm

Abstract

The utility model discloses a puncture-resistant sodium battery diaphragm. The puncture-resistant sodium battery diaphragm comprises a base membrane, the ceramic particle coating is arranged on the surface of at least one side of the base membrane, the ceramic particle coating is provided with a pore structure which is uniformly distributed, and the pore diameter range of the pore structure is 0.1-0.5 mu m; the nano-fiber reinforced coating is arranged on the outer surface of the ceramic particle coating, nano-fibers in the nano-fiber reinforced coating form a net-shaped reinforced structure, the nano-fibers are aramid nano-fibers, the diameter of the aramid nano-fibers is 10-50 nm, and the length of the aramid nano-fibers is 1-10 [mu] m; wherein the puncture resistant strength of the diaphragm is 600 to 1000 gf. Compared with the prior art, according to the sodium battery diaphragm disclosed by the utility model, the ceramic particle coating and the nanofiber reinforced coating are arranged on the surface of the base membrane, so that the mechanical strength and the puncture resistance of the diaphragm are obviously enhanced, and meanwhile, the thermal stability of the diaphragm is also effectively improved.

Description

Technical Field

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

[0002] With the increasing popularity of renewable energy utilization and the rapid development of electrochemical energy storage technology, the research and application of new battery systems are constantly expanding. Among the many types of batteries, sodium batteries are gradually gaining attention from industry and research institutions due to their advantages such as abundant sodium resources, relatively low cost, and the potential for continuous performance improvement. However, the separator, as one of the key components of existing sodium batteries, has not yet fully met practical needs, especially in terms of stability under high-temperature conditions and mechanical damage resistance, where there is still considerable room for improvement.

[0003] Currently, the widely used sodium battery separators are typically made of polyolefin materials (such as polyethylene, polypropylene) or their composites. These traditional separators maintain their morphology and ion conductivity well at lower temperatures, but they are prone to softening, shrinkage, and even melting at high temperatures, leading to a short-circuit risk in sodium batteries under high heat loads. Furthermore, traditional separators generally suffer from insufficient puncture resistance due to their structure and materials. When the battery is subjected to external pressure, puncture, or accidental impact, the fragile separator is easily punctured, forming an internal short circuit, which severely affects the battery's cycle life and safety.

[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 puncture-resistant sodium battery separator to address the shortcomings of existing technologies, thereby solving the problems of insufficient puncture resistance and poor temperature resistance of existing sodium battery separators.

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

[0007] A puncture-resistant sodium battery separator, comprising:

[0008] Base film;

[0009] A ceramic particle coating is disposed on at least one side surface of the base film, the ceramic particle coating having a uniformly distributed pore structure with a pore size ranging from 0.1 to 0.5 μm;

[0010] A nanofiber-reinforced coating is disposed on the outer surface of the ceramic particle coating. The nanofibers in the nanofiber-reinforced coating form a network reinforcement structure. The nanofibers are aramid nanofibers with a diameter of 10-50 nm and a fiber length of 1-10 μm.

[0011] The puncture resistance of the diaphragm is 600-1000 gf.

[0012] Furthermore, the base film is formed by a biaxial stretching process and has a microporous structure with uniformly distributed pores in both the longitudinal and transverse directions. The pore size of the microporous structure ranges from 0.05 to 0.2 μm, and the porosity is from 40% to 60%.

[0013] Furthermore, the outer surface of the nanofiber reinforced coating is also provided with a wetting aid coating, the thickness of which is 0.5–2 μm.

[0014] Furthermore, the wetting coating is a mixture of sulfonated polyether ether ketone (SPEEK) and PVDF, wherein the weight percentage of sulfonated polyether ether ketone is 50% to 70%, and the weight percentage of PVDF is 30% to 50%.

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

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

[0017] Furthermore, the thickness of the ceramic particle coating is 2–5 μm.

[0018] Furthermore, the thickness of the nanofiber reinforced coating is 1–5 μm.

[0019] Furthermore, the nanofiber reinforced coating comprises aramid nanofibers and a binder, wherein the binder is PVDF.

[0020] Furthermore, the ceramic particle coating comprises ceramic particles and a binder, wherein the binder is PVDF and the ceramic particles are silicon oxide, zirconium oxide, or aluminum oxide.

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

[0022] 1) The sodium battery separator of this invention significantly enhances the mechanical strength and puncture resistance of the separator by setting a ceramic particle coating and a nanofiber reinforced coating on the surface of the base membrane. The ceramic particle coating has a uniformly distributed pore structure, which can effectively disperse external impact forces and prevent puncture objects from directly penetrating the base membrane. The aramid nanofibers in the nanofiber reinforced coating form a network structure, which further enhances the overall puncture resistance of the separator, making the puncture strength of the separator reach 600-1000 gf, which is much higher than that of traditional separators, and significantly improves the safety of sodium batteries in practical applications.

[0023] 2) The ceramic particle coating of this utility model not only provides mechanical reinforcement but also has excellent thermal stability. The ceramic particle coating can maintain a stable structure and performance at high temperatures, preventing the separator from softening or melting in high-temperature environments, thereby effectively improving the reliability and safety of sodium batteries under high-temperature conditions. 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] Figure 2 This is a schematic diagram of the structure of a sodium battery separator in another embodiment of the present invention.

[0026] In the figure: 1. Base film; 2. Ceramic particle coating; 3. Nanofiber reinforced coating; 4. Wetting aid coating. Detailed Implementation

[0027] 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.

[0028] like Figure 1 As shown, this application provides a puncture-resistant sodium battery separator, comprising:

[0029] Base film 1;

[0030] A ceramic particle coating 2 is disposed on at least one side surface of the base film 1. The ceramic particle coating 2 has a uniformly distributed pore structure with a pore size ranging from 0.1 to 0.5 μm.

[0031] Nanofiber reinforced coating 3 is disposed on the outer surface of ceramic particle coating 2. The nanofibers in nanofiber reinforced coating 3 form a network reinforcement structure. The nanofibers are aramid nanofibers with a diameter of 10-50 nm and a fiber length of 1-10 μm.

[0032] The puncture resistance of the diaphragm is 600–1000 gf; more preferably 800–1000 gf.

[0033] The puncture-resistant sodium battery separator provided in this application has the following advantages:

[0034] 1) Improved puncture resistance: The sodium battery separator of this application significantly enhances the mechanical strength and puncture resistance of the separator by depositing a ceramic particle coating 2 and a nanofiber reinforced coating 3 on the surface of the base membrane 1. The ceramic particle coating 2 has a uniformly distributed pore structure, which can effectively disperse external impact forces and prevent puncture objects from directly penetrating the base membrane 1. The aramid nanofibers in the nanofiber reinforced coating 3 form a network structure, which further enhances the overall puncture resistance of the separator, making the puncture strength of the separator reach 600-1000 gf, which is much higher than that of traditional separators, and significantly improves the safety of sodium batteries in practical applications.

[0035] 2) Improved temperature resistance: The ceramic particle coating 2 of this application not only provides mechanical reinforcement but also has excellent thermal stability; ceramic materials such as silicon oxide, zirconium oxide and alumina can still maintain stable structure and performance at high temperatures, preventing the separator from softening or melting in high-temperature environments, thereby effectively improving the reliability and safety of sodium batteries under high-temperature conditions.

[0036] In one embodiment of this application, the base membrane 1 is formed by a biaxial stretching process and has a microporous structure with uniformly distributed pores in both the longitudinal and transverse directions. The pore size of the microporous structure ranges from 0.05 to 0.2 μm, and the porosity is 40% to 60%. The base membrane 1 of this application, with its uniformly distributed microporous structure in both the longitudinal and transverse directions formed by the biaxial stretching process, has a pore size range of 0.05 to 0.2 μm and a porosity of 40% to 60%, provides a good ion conduction path while ensuring the mechanical strength of the separator. This structural design effectively balances the ion resistance and mechanical properties of the separator, ensuring the efficient operation of the sodium battery during charging and discharging.

[0037] like Figure 2 As shown, in one embodiment according to this application, the outer surface of the nanofiber reinforced coating 3 is further provided with a wetting aid coating 4, the thickness of which is 0.5–2 μm. The wetting aid coating 4 on the outer surface of the nanofiber reinforced coating 3 improves the interfacial compatibility between the separator, electrolyte, and electrode materials; the wetting aid coating 4 can enhance the wettability of the separator, strengthen the wetting ability of the electrolyte, and promote rapid ion migration, thereby improving the overall performance of the battery.

[0038] In one embodiment of this application, the wetting aid coating 4 is a mixture of sulfonated polyether ether ketone (SPEEK) and PVDF, wherein the weight percentage of sulfonated polyether ether ketone is 50%–70%, and the weight percentage of PVDF is 30%–50%. The wetting aid coating 4 uses a mixture of sulfonated polyether ether ketone (SPEEK) and PVDF, where SPEEK has good hydrophilicity, improving the wettability of the separator, while PVDF provides excellent mechanical strength and chemical stability. The combination of the two optimizes the interfacial performance of the separator. The thickness of the wetting aid coating 4 is controlled between 0.5 and 2 μm to ensure the functionality and uniformity of the coating, while avoiding excessive thickness that would increase the internal resistance of the battery, thus improving the overall performance of the battery.

[0039] In one embodiment of this application, the base film 1 is a PP film, a PE film, or a PI film. The base film 1 can be selected from PP, PE, or PI films to meet the needs of different sodium battery applications. PP and PE films have good chemical stability and cost advantages, while PI films offer higher temperature resistance, adapting to more demanding working environments.

[0040] In one embodiment according to this application, the thickness of the base membrane 1 is 10–15 μm. This reasonable thickness design ensures the full functionality of each layer while avoiding performance degradation due to excessive thickness, thus optimizing the overall performance of the membrane.

[0041] In one embodiment of this application, the thickness of the ceramic particle coating 2 is 2–5 μm. Controlling the thickness of the ceramic particle coating 2 to 2–5 μm ensures the uniformity and effectiveness of the coating, while avoiding increased ion conduction resistance due to excessive thickness, thus optimizing the overall performance of the diaphragm.

[0042] In one embodiment according to this application, the thickness of the nanofiber-reinforced coating 3 is 1–5 μm. This ensures high performance while minimizing the weight and thickness of the separator, making it suitable for practical applications in high-energy-density sodium batteries.

[0043] In one embodiment of this application, the nanofiber-reinforced coating 3 comprises aramid nanofibers and a binder, wherein the binder is PVDF. The aramid nanofibers possess excellent high-temperature resistance and mechanical strength, with a diameter of 10–50 nm and a fiber length of 1–10 μm. The resulting network structure effectively disperses and absorbs external impact forces, further enhancing the puncture resistance of the diaphragm. Using PVDF as the binder for the nanofiber-reinforced coating 3 enhances the overall stability and adhesion of the coating, ensuring the durability and effectiveness of the nanofiber network structure.

[0044] In one embodiment of this application, the ceramic particle coating 2 includes ceramic particles and a binder, wherein the binder is PVDF, and the ceramic particles are silicon oxide, zirconium oxide, or alumina. The selection of silicon oxide, zirconium oxide, or alumina as ceramic particles not only improves the temperature resistance of the diaphragm but also enhances its overall durability through its inherent thermal stability and mechanical strength. PVDF possesses excellent chemical stability and mechanical strength, ensuring uniform dispersion and strong bonding of the ceramic particles in the coating, thereby improving the overall stability and durability of the coating.

[0045] 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 puncture-resistant sodium battery separator, characterized in that, include: Base film; A ceramic particle coating is disposed on at least one side surface of the base film, the ceramic particle coating having a uniformly distributed pore structure with a pore size ranging from 0.1 to 0.5 μm; A nanofiber-reinforced coating is disposed on the outer surface of the ceramic particle coating. The nanofibers in the nanofiber-reinforced coating form a network reinforcement structure. The nanofibers are aramid nanofibers with a diameter of 10-50 nm and a fiber length of 1-10 μm. The puncture resistance of the diaphragm is 600-1000 gf.

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

3. The puncture-resistant sodium battery separator according to claim 1 or 2, characterized in that: The outer surface of the nanofiber reinforced coating is further provided with a wetting aid coating, the thickness of which is 0.5 to 2 μm.

4. The puncture-resistant sodium battery separator according to claim 1, characterized in that: The base film is a PP film, a PE film, or a PI film.

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

6. The puncture-resistant sodium battery separator according to claim 1, characterized in that: The thickness of the ceramic particle coating is 2–5 μm.

7. The puncture-resistant sodium battery separator according to claim 1, characterized in that: The thickness of the nanofiber reinforced coating is 1–5 μm.

8. The puncture-resistant sodium battery separator according to claim 1, characterized in that: The ceramic particles in the ceramic particle coating are silicon oxide, zirconium oxide, or aluminum oxide.

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