Sodium-supplementing battery diaphragm structure and sodium ion battery

Abstract

The utility model provides a sodium-supplementing battery diaphragm structure and a sodium ion battery. The battery diaphragm structure comprises a base membrane, and a sodium-supplementing layer, a catalyst layer and a conductive layer which are sequentially laminated on the surface of any side of the base membrane. Through the specific design of the battery diaphragm structure, efficient and stable sodium compensation can be realized on the premise of not increasing additional process burden, so that the cycle life of the battery is prolonged, and the overall performance of the battery is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of sodium ion batteries and relates to a sodium-supplemented battery diaphragm structure and a sodium ion battery. Background Art

[0002] With the global energy transition and the rapid development of renewable energy, energy storage technology has become crucial for supporting smart grids, electric vehicles, and distributed energy systems. Lithium-ion batteries, owing to their high energy density and mature industrial chain, have dominated the market for decades. However, the limited availability and high cost of lithium resources have prompted researchers and industry to actively explore alternative energy storage technologies. Sodium-ion batteries, with their abundant raw materials, low cost, and environmental friendliness, have emerged as one of the most promising next-generation energy storage technologies.

[0003] Despite their numerous advantages, sodium-ion batteries (Na-ion batteries) face several technical challenges in their commercialization. Among them, Na-ion batteries are prone to sodium loss during long-term cycling, which leads to continuous capacity degradation and severely shortens their service life.

[0004] The main reasons for the loss include the repeated embedding and extraction of sodium ions between the positive and negative electrode materials during the charge and discharge process. Some sodium ions will be irreversibly consumed due to side reactions (such as electrolyte decomposition, unstable growth of solid electrolyte interface membrane, etc.), resulting in a gradual decrease in the active sodium in the battery system. Especially under high voltage or high temperature conditions, the side reactions are intensified, further accelerating the sodium loss.

[0005] Existing sodium-ion battery designs typically fail to consider sodium compensation mechanisms. While conventional lithium-ion batteries can compensate for lithium loss through lithium replenishment techniques (such as pre-lithiation additives and sacrificial cathode materials), research into sodium replenishment technologies for sodium-ion batteries is relatively underdeveloped. While some studies have attempted to add sodium-containing compounds to electrode materials to provide an additional sodium source, these methods often suffer from complex processes, high costs, or low efficiency, making them difficult to scale up.

[0006] Furthermore, the packaging structures of existing sodium-ion batteries largely mirror those of lithium-ion batteries, lacking optimization for sodium compensation. For example, hard-shell and soft-pack batteries typically employ a closed structure, making it difficult to dynamically replenish the sodium source during battery cycling. While some studies have proposed dissolving sodium salts in the electrolyte to replenish sodium ions, this approach struggles to maintain effective sodium compensation over the long term due to the solubility and stability limitations of sodium salts.

[0007] In summary, existing sodium-ion batteries face severe sodium loss and rapid capacity decay during long-term cycling. Traditional sodium replenishment technologies are also subject to drawbacks such as complex processes, high costs, low efficiency, difficulty in application, and high environmental requirements. Therefore, there is an urgent need to develop a novel battery separator structure and sodium-ion battery that overcomes the drawbacks of existing technologies and meets practical application needs. Utility Model Content

[0008] In response to the shortcomings of the existing technology, the purpose of the present invention is to provide a sodium-supplemented battery diaphragm structure and a sodium-ion battery. In the present invention, through the specific design of the battery diaphragm structure, efficient and stable sodium compensation can be achieved without adding additional process burden, thereby improving the cycle life and overall performance of the battery.

[0009] To achieve this purpose, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides a sodium-supplemented battery diaphragm structure, wherein the sodium-ion battery structure comprises a base membrane, and a sodium-supplemented layer, a catalytic layer, and a conductive layer sequentially stacked on either side of the base membrane.

[0011] In the present invention, through the specific design of the battery diaphragm structure, efficient and stable sodium compensation can be achieved without adding additional process burden, thereby improving the cycle life and overall performance of the battery.

[0012] As a preferred technical solution of the present invention, the base membrane is a glass fiber base membrane.

[0013] As a preferred technical solution of the present invention, the thickness of the glass fiber base membrane is 200μm~260μm, for example, it can be 200μm, 210μm, 220μm, 230μm, 240μm, 250μm, 260μm, etc., but it is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0014] As a preferred technical solution of the present invention, the sodium supplement layer is a sodium oxalate layer or a sodium squarate layer.

[0015] As a preferred technical solution of the present invention, the thickness of the sodium supplement layer is 5μm~10μm, for example, it can be 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, etc., but is not limited to the listed values. Other unlisted values ​​within this numerical range are also applicable.

[0016] As a preferred technical solution of the present invention, the catalytic layer is a nickel oxide layer or a cobalt oxide layer, and the catalytic layer has a grid structure.

[0017] As a preferred technical solution of the present invention, the mesh size of the catalytic layer is 400 mesh to 450 mesh, for example, it can be 400 mesh, 410 mesh, 420 mesh, 430 mesh, 440 mesh, 450 mesh, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0018] As a preferred technical solution of the present invention, the thickness of the catalytic layer is 50nm~100nm, for example, it can be 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, etc., but it is not limited to the listed values. Other unlisted values ​​within this numerical range are also applicable.

[0019] As a preferred technical solution of the present invention, the conductive layer is a polyaniline layer.

[0020] As a preferred technical solution of the present invention, the thickness of the conductive layer is 100nm~300nm, for example, it can be 100nm, 120nm, 140nm, 160nm, 180nm, 200nm, 220nm, 240nm, 260nm, 280nm, 300nm, etc., but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0021] In a second aspect, the present invention provides a sodium ion battery, which includes the sodium-supplementing battery diaphragm structure described in the first aspect.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] In the present invention, through the specific design of the battery diaphragm structure, efficient and stable sodium compensation can be achieved without adding additional process burden, thereby improving the cycle life and overall performance of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram of a sodium-supplemented battery separator structure provided in one embodiment of the present invention;

[0025] Among them, 1-base membrane; 2-sodium supplement layer; 3-catalytic layer; 4-conductive layer. DETAILED DESCRIPTION

[0026] It should be understood that, in the description of the present invention, the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0027] It should be noted that, in the description of this utility model, unless otherwise expressly specified or limited, the terms "disposed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; direct connections, indirect connections through an intermediate medium, and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0028] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific implementation methods.

[0029] In a specific embodiment, the present invention provides a sodium-supplemented battery separator structure, such as Figure 1 As shown, the sodium ion battery structure includes a base membrane 1, and a sodium supplement layer 2, a catalytic layer 3 and a conductive layer 4 stacked in sequence on either side of the base membrane 1.

[0030] It should be noted that the present invention adopts a combined structure of a base membrane 1, a sodium replenishing layer 2, a catalytic layer 3 and a conductive layer 4 designed with specific materials and relevant parameters. The material of each layer is indispensable, does not affect the processing of the positive and negative electrodes, and has low environmental requirements. Only in this way can the sodium replenishing effect of the sodium ion battery structure be maximized, thereby achieving efficient and stable sodium compensation.

[0031] It should be noted that, in the present invention, any side of the base film 1 including any surface or multiple surfaces of the base film 1 can be sequentially stacked with the sodium supplement layer 2, the catalytic layer 3 and the conductive layer 4.

[0032] In one embodiment, the base film 1 is a glass fiber base film.

[0033] It should be noted that the glass fiber base membrane in the present invention includes a basic material and a binder. The basic material includes silicate glass fiber (main components are SiO2, Al2O3, CaO, etc.), which has a high melting point (usually >1000°C) and chemical inertness. Some high-performance glass fibers may contain borosilicate or quartz glass fibers to further improve temperature resistance and mechanical strength; the binder can be a small amount of organic polymer (such as polyacrylate, polyvinylidene fluoride PVDF) to enhance the bonding force between fibers, but the content needs to be controlled to avoid affecting the wettability of the electrolyte.

[0034] It should be noted that the role of the glass fiber-based membrane in the sodium-ion battery in the present invention includes physically isolating the positive and negative electrodes to prevent direct contact between the positive and negative electrodes and causing a short circuit, while allowing sodium ions to pass freely to ensure the normal operation of the battery; high temperature resistance, the melting point of glass fiber is greater than 1000°C, which is much higher than that of polyolefin separators (PE / PP is about 130~170°C), which can effectively inhibit thermal shrinkage and reduce the risk of thermal runaway; flame retardancy, inorganic materials do not burn, and improve battery safety; three-dimensional mesh porous structure (porosity is usually greater than 80%) and liquid-philic surface, which can quickly absorb and retain electrolyte, promote ion transport, and reduce interfacial impedance; the high rigidity of glass fiber can resist sodium dendrite puncture and extend battery life (especially under high voltage or fast charging conditions); no side reactions to electrolytes (such as NaPF6 / carbonate system) and electrode materials, and long-term cycle stability is better than that of organic separators.

[0035] In one embodiment, the thickness of the glass fiber base membrane is 200μm~260μm, for example, it can be 200μm, 210μm, 220μm, 230μm, 240μm, 250μm, 260μm, etc., but is not limited to the listed values. Other unlisted values ​​within this numerical range are also applicable.

[0036] The thickness of the glass fiber base membrane is selected to be 200 μm to 260 μm in the present invention because a too large thickness of the glass fiber base membrane affects the ion transmission efficiency, while a too small thickness leads to too low mechanical strength.

[0037] In one embodiment, the sodium supplementation layer 2 is a sodium oxalate layer or a sodium squarate layer.

[0038] It should be noted that the sodium supplement layer 2 in the present invention can be a sodium oxalate layer or a sodium squarate layer. After sodium supplementation, the product is discharged in the form of gas, which will not affect the normal structure of the sodium ion battery. If a sodium oxalate layer is used alone, its loading capacity is 0.2-2 mg / cm 2 , using a single sodium squarate layer, the loading capacity is 0.2-2 mg / cm 2 .

[0039] In one embodiment, the thickness of the sodium supplement layer 2 is 5 μm to 10 μm, for example, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0040] The thickness of the sodium-supplementing layer 2 is selected to be 5 μm to 10 μm in the present invention because when the thickness of the sodium-supplementing layer 2 is too large, the excessive sodium-supplementing agent cannot form uniform contact with the catalyst and the conductive layer 4, the catalytic effect of the uncontacted part is poor, and the decomposition voltage is high; when the thickness of the sodium-supplementing layer 2 is too small, the sodium-supplementing agent loading amount is too small, which affects the sodium-supplementing effect of the sodium-supplementing membrane.

[0041] In one embodiment, the catalytic layer 3 is a nickel oxide layer or a cobalt oxide layer, and the catalytic layer 3 has a grid structure.

[0042] It should be noted that the catalytic layer 3 in the present invention can be a nickel oxide layer or a cobalt oxide layer. If the nickel oxide layer is used alone, its usage can be 1%-8% of the mass of the sodium supplement agent. If the cobalt oxide layer is used alone, its usage can be 1%-8% of the mass of the sodium supplement agent.

[0043] It should be noted that the catalytic layer 3 with a grid structure in the present invention can effectively reduce the risk of decomposition voltage of the sodium supplement agent and ensure effective contact between the sodium supplement agent and the conductive layer 4. The shape of the grid can be circular, square, etc., and is not specifically limited here. Those skilled in the art can make adaptive adjustments according to actual conditions.

[0044] In one embodiment, the mesh size of the catalytic layer 3 is 400-450 mesh, for example, it can be 400 mesh, 410 mesh, 420 mesh, 430 mesh, 440 mesh, 450 mesh, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0045] In the present invention, the mesh number of the catalytic layer 3 is selected to be 400 mesh to 450 mesh because within this range, the risk of decomposition voltage of the sodium supplement agent can be effectively reduced, ensuring effective contact between the sodium supplement agent and the conductive layer 4. If the mesh number is too large, it will affect the contact between the conductive layer 4 and the sodium supplement layer 2. If the mesh number is too small, it will not be possible to ensure uniform and effective contact between the catalytic layer 3 and the sodium supplement layer 2.

[0046] In one embodiment, the thickness of the catalytic layer 3 is 50 nm to 100 nm, for example, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0047] In the present invention, the thickness of the catalytic layer 3 is selected to be 50nm~100nm. The catalyst itself does not play a sodium supplementing effect, but only plays a catalytic role. Therefore, the catalytic layer 3 only needs to ensure that the amount of catalyst is sufficient. If the thickness of the catalytic layer 3 is too large, it will affect the contact between the sodium supplement and the conductive layer 4, and introduce invalid mass.

[0048] In one embodiment, the conductive layer 4 is a polyaniline layer.

[0049] It should be noted that the conductive layer 4 of polyaniline is selected in the present invention, which can make the overall structure thin, thereby facilitating the assembly and subsequent operation of the battery.

[0050] In one embodiment, the thickness of the conductive layer 4 is 100 nm to 300 nm, for example, it can be 100 nm, 120 nm, 140 nm, 160 nm, 180 nm, 200 nm, 220 nm, 240 nm, 260 nm, 280 nm, 300 nm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0051] In the present invention, the thickness of the conductive layer 4 is selected to be 100nm~300nm. The functions of the conductive layer 4 include: (1) providing sufficient conductivity for the particles of the sodium supplement layer 2, and (2) the conductive layer 4 with a complete structure will improve the air stability of the sodium supplement layer 2; if the thickness is too small, it will cause part of the position to be exposed, affecting the conductivity and stability; if the thickness is too large, it will affect the overall thickness of the diaphragm and affect the ion permeability of the diaphragm.

[0052] In another specific embodiment, the present invention provides a sodium ion battery, which includes the sodium-supplementing battery diaphragm structure described in the first aspect.

[0053] In one embodiment, the positive electrode sheet, the base film 1 and its related design structure, the negative electrode sheet and the electrolyte can be made into the above-mentioned sodium ion battery.

[0054] In one embodiment, the outer packaging of the sodium-ion battery can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of the battery cell can also be a soft shell, such as a pouch-type soft shell. The soft shell can be made of plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0055] Example 1

[0056] This embodiment provides a sodium-supplemented battery separator structure, wherein:

[0057] The invention comprises a glass fiber base membrane, and a sodium supplement layer 2, a catalytic layer 3 and a conductive layer 4 which are sequentially stacked on one side surface of the glass fiber base membrane.

[0058] The thickness of the glass fiber base membrane is 200 μm.

[0059] The sodium supplement layer 2 is a sodium oxalate layer with a thickness of 8 μm and a sodium oxalate loading of 1 mg / cm 2 .

[0060] The catalytic layer 3 is a nickel oxide layer, and the catalytic layer 3 has a grid structure. The mesh number of the catalytic layer 3 is 400 meshes, and the thickness of the catalytic layer 3 is 50 nm.

[0061] The conductive layer 4 is a polyaniline layer, and the thickness of the conductive layer 4 is 200 nm.

[0062] Example 2

[0063] This embodiment provides a sodium-supplemented battery separator structure, wherein:

[0064] The invention comprises a glass fiber base membrane, and a sodium supplement layer 2, a catalytic layer 3 and a conductive layer 4 which are sequentially stacked on one side surface of the glass fiber base membrane.

[0065] The thickness of the glass fiber base membrane is 240 μm.

[0066] The sodium supplement layer 2 is a sodium oxalate layer with a thickness of 5 μm and a sodium oxalate loading of 0.63 mg / cm 2 .

[0067] The catalytic layer 3 is a cobalt tetroxide layer, and the catalytic layer 3 has a grid structure. The mesh number of the catalytic layer 3 is 420 meshes, and the thickness of the catalytic layer 3 is 80 nm.

[0068] The conductive layer 4 is a polyaniline layer, and the thickness of the conductive layer 4 is 100 nm.

[0069] Example 3

[0070] This embodiment provides a sodium-supplemented battery separator structure, wherein:

[0071] The invention comprises a glass fiber base membrane, and a sodium supplement layer 2, a catalytic layer 3 and a conductive layer 4 which are sequentially stacked on one side surface of the glass fiber base membrane.

[0072] The thickness of the glass fiber base membrane is 200μm~260μm.

[0073] The sodium supplement layer 2 is a sodium squarate layer, and the thickness of the sodium supplement layer 2 is 10 μm.

[0074] The catalytic layer 3 is a nickel oxide layer, and the catalytic layer 3 has a grid structure. The mesh number of the catalytic layer 3 is 450 meshes, and the thickness of the catalytic layer 3 is 100 nm.

[0075] The conductive layer 4 is a polyaniline layer, and the thickness of the conductive layer 4 is 300 nm.

[0076] Example 4

[0077] This embodiment provides a sodium-supplemented battery separator structure, which differs from Example 1 in that the thickness of the glass fiber base membrane is 180 μm, and the other parameters and conditions are the same as those in Example 1.

[0078] Example 5

[0079] This embodiment provides a sodium-supplemented battery separator structure, which differs from Example 1 in that the thickness of the glass fiber base membrane is 280 μm, and the other parameters and conditions are the same as those in Example 1.

[0080] Example 6

[0081] This embodiment provides a sodium-supplemented battery separator structure, which differs from Example 1 in that the thickness of the sodium-supplemented layer 2 is 3 μm, and the other parameters and conditions are the same as those in Example 1.

[0082] Example 7

[0083] This embodiment provides a sodium-supplemented battery separator structure, which differs from Example 1 in that the thickness of the sodium-supplemented layer 2 is 12 μm, and the other parameters and conditions are the same as those in Example 1.

[0084] Example 8

[0085] This embodiment provides a sodium-supplemented battery separator structure, which differs from Example 1 in that the thickness of the catalytic layer 3 is 40 nm, and the other parameters and conditions are the same as those in Example 1.

[0086] Example 9

[0087] This embodiment provides a sodium-supplemented battery separator structure, which differs from Example 1 in that the thickness of the catalytic layer 3 is 120 nm, and the other parameters and conditions are the same as those in Example 1.

[0088] Comparative Example 1

[0089] This comparative example provides a sodium-supplemented battery diaphragm structure, which differs from Example 1 in that no catalyst layer is provided, and other parameters and conditions are the same as those of Example 1.

[0090] The sodium supplementation effect of the battery separator structures described in the above examples and comparative examples was tested using button cells. Specifically, the battery separator structures obtained in the examples and comparative examples were sliced ​​and used as separators. These cells were then assembled into sodium-ion button cells using carbon-coated aluminum foil and a sodium metal electrode. The sodium supplementation layer 2 of the sodium supplementation separator was located on one side of the carbon-coated aluminum foil. An electrolyte solution was prepared by dissolving 1M sodium perchlorate in polycarbonate (PC) / fluoroethylene carbonate (FEC) (mass ratio 97:3). After the button cells were assembled, capacity tests were performed as follows: The cells were allowed to stand for 2 hours. The cells were then charged and discharged over a voltage range of 2.0-4.5V (i.e., constant current charging at 0.1C to 4.5V, followed by a constant voltage cutoff of 4.5V at 0.05C). The rated gram capacity was 350mAh / g. The test results represent the area-specific capacity of the battery separator structures and the mass-specific capacity based on the mass of the lithium salt. The results are shown in Table 1 below.

[0091]

[0092] In summary, the utility model can achieve efficient and stable sodium compensation through the specific design of the battery diaphragm structure without adding additional process burden, thereby improving the cycle life and overall performance of the battery.

[0093] The above description is only a specific implementation method of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in the present invention fall within the protection scope and disclosure scope of the present invention.

Claims

1. A sodium-supplemented battery separator structure, characterized in that: The battery separator structure comprises a base membrane, and a sodium supplement layer, a catalytic layer and a conductive layer which are sequentially stacked on the surface of either side of the base membrane.

2. The sodium-supplemented battery separator structure according to claim 1, characterized in that: The base membrane is a glass fiber base membrane.

3. The sodium-supplemented battery separator structure according to claim 2, characterized in that: The thickness of the glass fiber base membrane is 200 μm to 260 μm.

4. The sodium-supplemented battery separator structure according to claim 1, characterized in that: The sodium supplement layer is a sodium oxalate layer or a sodium squarate layer.

5. The sodium-supplemented battery separator structure according to claim 1, characterized in that: The thickness of the sodium supplement layer is 5 μm to 10 μm.

6. The sodium-supplemented battery separator structure according to claim 1, characterized in that: The catalytic layer is a nickel oxide layer or a cobalt oxide layer, and the catalytic layer has a grid structure.

7. The sodium-supplemented battery separator structure according to claim 6, characterized in that: The mesh size of the catalytic layer is 400-450 meshes.

8. The sodium-supplemented battery separator structure according to claim 1, characterized in that: The thickness of the catalytic layer is 50nm~100nm.

9. The sodium-supplemented battery separator structure according to claim 1, characterized in that: The conductive layer is a polyaniline layer, and the thickness of the conductive layer is 100 nm to 300 nm.

10. A sodium ion battery, characterized in that: The sodium ion battery comprises the sodium-supplemented battery separator structure according to any one of claims 1 to 9.

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