Sodium-ion battery cell

Abstract

The utility model discloses a sodium ion battery cell which comprises a positive plate, a negative plate and a diaphragm used for isolating the positive plate from the negative plate, one side surface or two side surfaces of the diaphragm is / are coated with a multi-tooth polymeric monomer coating, or one side surface or two side surfaces of the positive plate or the negative plate is / are coated with a multi-tooth polymeric monomer coating. And the multi-tooth polymeric monomer coating is subjected to in-situ polymerization in the formation process to form an adhesion structure of the diaphragm, the positive plate and the negative plate. The sodium ion battery cell disclosed by the utility model has the characteristics of simple process, high safety and good interface compatibility.

Description

Technical Field

[0001] The present utility model relates to the technical field of sodium-ion batteries, and specifically refers to a sodium-ion battery cell core. Background Art

[0002] A sodium-ion battery is a secondary battery (rechargeable battery) that mainly operates by the movement of sodium ions between the positive electrode and the negative electrode, and has a working principle similar to that of a lithium-ion battery. Sodium-ion batteries have the advantages of high safety, long life, and low cost compared to lithium-ion batteries.

[0003] In a sodium-ion battery, the battery structure has an important impact on the battery performance. In particular, the bonding and fixing effect between its electrode sheet and the separator directly affects the safety performance and cycle life of the battery.

[0004] In response to this, Chinese Utility Model Patent CN211017288U discloses a sodium-ion battery cell core, including: a sodium-ion battery positive electrode sheet, a sodium-ion battery negative electrode sheet, and a separator; wherein, the sodium-ion battery positive electrode sheet, the separator, the sodium-ion battery negative electrode sheet are connected in sequence according to the order of sodium-ion battery positive electrode sheet / separator / sodium-ion battery negative electrode sheet / separator, and an interfacial adhesion structure formed by hot pressing exists at the interface between the sodium-ion battery positive electrode sheet and the separator and at the interface between the sodium-ion battery negative electrode sheet and the separator. Through the interfacial adhesion structure formed by hot pressing between the interface of the positive electrode sheet and the separator and the interface of the negative electrode sheet and the separator, the bonding strength between the electrode sheet and the separator can be significantly improved, the distance between the positive and negative electrode sheets is shortened, thereby reducing the internal resistance of the battery and reducing the heat generation during high-rate operation; through this structure, the misalignment during the battery assembly process can also be prevented, and the deformation of the battery during the cycle process can be prevented, thereby significantly improving the safety performance and cycle life of the battery.

[0005] However, when using the hot pressing method, it is necessary to add a hot pressing process before the core winding or lamination, which increases the processing and manufacturing difficulty. Moreover, during the hot pressing process, there are also strict requirements for temperature control. If the hot pressing temperature is too high, the separator will shrink excessively, affecting the safety performance of the cell core. If the hot pressing temperature is too low, the interfacial adhesion structure cannot be formed, and the control difficulty is large, resulting in poor product consistency. Summary of the Utility Model

[0006] The purpose of the present utility model is to provide a sodium-ion battery cell core, which has the characteristics of simple process, high safety, and good interfacial compatibility.

[0007] The present utility model can be realized through the following technical solutions:

[0008] The utility model discloses a sodium-ion battery cell, which includes a positive electrode sheet, a negative electrode sheet, and a separator for isolating the positive electrode sheet and the negative electrode sheet. One side or both sides of the separator are coated with a multi-tooth polymer monomer coating, or one side or both sides of the positive electrode sheet or the negative electrode sheet are coated with a multi-tooth polymer monomer coating. The multi-tooth polymer monomer coating forms an adhesion structure between the separator and the positive electrode sheet and the negative electrode sheet by in-situ polymerization during the formation process.

[0009] Further, the multi-tooth polymer monomer coating is a 2,2-dimethyl-1,3-propanediol diacrylate material layer or a trimethylolpropane triacrylate material layer. It not only realizes the function of in-situ polymerization adhesion and fixation, but also the in-situ polymerization product has good interfacial compatibility with the electrolyte, improving the battery performance.

[0010] Further, the positive electrode sheet includes a positive electrode current collector and a positive electrode material layer coated on the surface of the positive electrode current collector, which directly uses the existing process and has relatively excellent applicability.

[0011] Further, the positive electrode material layer is a polyanion-type positive electrode material layer, a Prussian blue material, or a layered oxide material layer, meeting the application requirements of different materials.

[0012] Further, the polyanion-type material layer is a composite sodium iron sulfate material layer or a composite sodium iron phosphate material layer.

[0013] Further, the negative electrode sheet includes a negative electrode current collector and a negative electrode material layer coated on the surface of the negative electrode current collector. The negative electrode material layer is a hard carbon material layer or a soft carbon material layer, meeting the usage requirements of different negative electrode materials.

[0014] Further, the positive electrode current collector and the negative electrode current collector are aluminum foil, coated aluminum foil, aluminum mesh, copper foil, copper mesh, or coated copper foil.

[0015] Further, the separator is a polyolefin film, and the polyolefin film is a PP film, a PE film, or a PP / PE composite film.

[0016] Further, the multi-tooth polymer monomer coating is coated on the surface of the separator, the positive electrode, or the negative electrode sheet by means of knife coating, spraying, or roll coating, and the process has strong applicability.

[0017] Further, the sodium-ion battery cell is a steel shell cylindrical cell, an aluminum shell square cell, or an aluminum plastic film square cell. It effectively improves the energy density of the battery.

[0018] The sodium-ion battery cell of the utility model has the following beneficial effects:

[0019] First, the process is simple. By setting the multi-tooth polymer monomer coating in the utility model, the multi-tooth polymer monomer coating between the electrode sheet and the separator can be completely fixed by in-situ polymerization after the high-temperature formation of the sodium-ion battery. The curing process is simple and fast, and no hot pressing is required;

[0020] Second, good safety. During the in-situ polymerization and curing process of the multi-tooth polymerized monomer coating of the utility model, the heat generated during formation is used to initiate the in-situ polymerization and curing of the system, which has extremely high safety and avoids potential safety hazards caused by uneven hot pressing or insufficient pressure.

[0021] Third, good interfacial compatibility. The highly cross-linked network polymer formed by polymerizing multi-tooth monomers has more polar carbonyl groups. They can weaken the interaction between sodium ions and the solvent by dipole-dipole interaction with the double bond of the solvent, thereby enhancing the interfacial interaction between sodium ions and anions. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic exploded view of a sodium-ion battery cell of the present utility model;

[0023] The reference numerals in the drawings include: 100, positive electrode sheet; 200, separator; 300, negative electrode sheet; 400, multi-tooth polymerized monomer coating. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] In order to enable those skilled in the art to better understand the technical solutions of the present utility model, the products of the present utility model will be further described in detail below with reference to the embodiments.

[0025] As Figure 1 shown, the present utility model discloses a sodium-ion battery cell, which includes a positive electrode sheet 100, a negative electrode sheet 200, and a separator 300 for isolating the positive electrode sheet 100 and the negative electrode sheet 200. One side or both sides of the separator 300 are coated with a multi-tooth polymerized monomer coating 400, or one side or both sides of the positive electrode sheet 100 or the negative electrode sheet 200 are coated with a multi-tooth polymerized monomer coating 400. The multi-tooth polymerized monomer coating 400 forms an adhesion structure between the separator 300 and the positive electrode sheet 100 and the negative electrode sheet 200 during formation. As Figure 1 shown, the multi-tooth polymerized monomer coating 400 is located between the positive electrode sheet 100 and the separator 300, and between the negative electrode sheet 200 and the separator 300. During the coating process, for two mutually contacting surfaces, as long as at least one surface is coated with the multi-tooth polymerized monomer coating 400, an adhesion structure can be formed by in-situ polymerization. Accordingly, in actual processing and manufacturing, it can be achieved by selecting to coat the surface of the positive electrode sheet 100, the negative electrode sheet 200 or the separator 300 as needed, which has stronger process feasibility. Specifically, the multi-tooth polymerized monomer coating is a layer of 2,2-dimethyl-1,3-propanediol diacrylate material or a layer of trimethylolpropane triacrylate material. However, in Figure 1 , it is not a structural limitation of the sodium-ion battery cell. Different negative electrode sheets, separators, and positive electrode sheets can be stacked or wound in this order to finally obtain a sodium-ion battery cell.

[0026] In the present utility model, it has a relatively wide applicability to the structures of the positive electrode and the negative electrode. For example, the positive electrode sheet includes a positive electrode current collector and a positive electrode material layer coated on the surface of the positive electrode current collector. Specifically, the positive electrode material layer is a polyanion-type positive electrode material layer, a Prussian blue material, or a layered oxide material layer. For example, the polyanion-type material layer is a composite sodium iron sulfate material layer or a composite sodium iron phosphate material layer. The negative electrode sheet includes a negative electrode current collector and a negative electrode material layer coated on the surface of the negative electrode current collector, and the negative electrode material layer is a hard carbon material layer or a soft carbon material layer.

[0027] Meanwhile, to simplify the process, the positive electrode current collector and the negative electrode current collector are aluminum foil, coated aluminum foil, aluminum mesh, copper foil, copper mesh, or coated copper foil. The separator is a polyolefin film, and the polyolefin film is a PP film, a PE film, or a PP / PE composite film.

[0028] In the specific implementation, the multi-tooth polymer monomer coating is coated on the surface of the separator, the positive electrode, or the negative electrode sheet by means of doctor blade coating, spraying, or roll coating, and the implementation process is relatively simple.

[0029] In the packaging structure of the specific battery cell, the sodium-ion battery cell is a steel shell cylindrical cell, an aluminum shell square cell, or an aluminum plastic film square cell.

[0030] In the multi-tooth polymer monomer coating of the present utility model, it mainly includes a multi-tooth polymer monomer material, and an initiator can also be appropriately added thereto. The initiator is a conventional initiator, such as azoisobutyronitrile (AIBN), benzoyl peroxide, cumene hydroperoxide, di-tert-butyl peroxide, tert-butyl perbenzoate, methyl ethyl ketone peroxide, and diisopropyl peroxydicarbonate. During the formation process, the interface between the separator and the electrode sheet can be in-situ immobilized by means of thermal initiation or initiator-initiated monomer polymerization, thereby achieving the effect of forming a bonding interface.

[0031] In the description of the present utility model, it should be understood that terms such as "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present utility model.

[0032] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present utility model, "a plurality" means two or more, unless otherwise specifically defined.

[0033] In the present utility model, unless otherwise clearly stipulated and defined, terms such as "installation", "connection", "linkage", "fixation" shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral one; it may be a mechanical connection or an electrical connection; it may be a direct connection or an indirect connection through an intermediate medium, and it may be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0034] The above embodiments are only specific embodiments of the present utility model, and the description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present utility model. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present utility model, several deformations and improvements can still be made, and these obvious replacement forms all belong to the protection scope of the present utility model.

Claims

1. A sodium-ion battery cell, comprising a positive electrode sheet, a negative electrode sheet, and a separator for isolating the positive electrode sheet and the negative electrode sheet, characterized in that: One side or both sides of the separator are coated with a multi-tooth polymerizable monomer coating, or one side or both sides of the positive electrode sheet or the negative electrode sheet are coated with a multi-tooth polymerizable monomer coating, and the multi-tooth polymerizable monomer coating is in-situ polymerized during formation to form an adhesion structure between the separator and the positive electrode sheet and the negative electrode sheet.

2. The sodium ion battery cell according to claim 1, wherein: The multi-tooth polymerizable monomer coating is a 2,2-dimethyl-1,3-propanediol diacrylate material layer or a trimethylolpropane triacrylate material layer.

3. The sodium ion battery cell according to claim 2, characterized in that: The positive electrode sheet includes a positive electrode current collector and a positive electrode material layer coated on the surface of the positive electrode current collector.

4. The sodium-ion battery cell according to claim 3, wherein: The positive electrode material layer is a polyanion-type positive electrode material layer, a Prussian blue material, or a layered oxide material layer.

5. The sodium-ion battery cell according to claim 4, wherein: The polyanion-type material layer is a sodium iron composite sulfate material layer or a sodium iron composite phosphate material layer.

6. The sodium ion battery cell according to claim 4, wherein: The negative electrode sheet includes a negative electrode current collector and a negative electrode material layer coated on the surface of the negative electrode current collector, and the negative electrode material layer is a hard carbon material layer or a soft carbon material layer.

7. The sodium ion battery cell according to claim 6, wherein: The positive electrode current collector and the negative electrode current collector are aluminum foil, coated aluminum foil, aluminum mesh, copper foil, copper mesh, or coated copper foil.

8. The sodium-ion battery cell according to claim 7, wherein: The separator is a polyolefin film, and the polyolefin film is a PP film, a PE film, or a PP / PE composite film.

9. The sodium-ion battery cell according to claim 8, characterized in that: The multi-tooth polymerizable monomer coating is coated on the surface of the separator, the positive electrode, or the negative electrode sheet by means of scraping, spraying, or roll coating.

10. The sodium-ion battery cell according to claim 9, wherein: The sodium ion battery cell is a steel shell cylindrical cell, an aluminum shell square cell, or an aluminum plastic film square cell.

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