Full tab sodium ion battery without negative electrode

Abstract

The utility model belongs to lithium ion battery technical field, concretely relates to a full tab's sodium electricity anodeless big cylindrical battery, include: big cylindrical full aluminium shell, set up in the full tab anodeless battery core pole group in the shell and the cooperation of battery cover plate, the battery core pole group is formed by the winding of positive plate, diaphragm and negative current collector, the positive plate top end reserved empty foil area constitutes full tab structure, the inner wall of shell is provided with carbon coating and is used as the negative current collector of sodium deposition. This patent has obtained the remarkable beneficial effect through the innovative fusion of big cylindrical full aluminium structure, full tab design and positive pole head and tail winding process. First, the big cylindrical full aluminium shell structure effectively balances the internal mechanical stress, completely gets rid of the dependence on the soft package battery clamp, and greatly widens the application scene of anodeless technology.

Description

Technical Field

[0001] This utility model belongs to the field of lithium-ion battery technology, specifically relating to a sodium-ion battery with no negative electrode and full tabs. Background Technology

[0002] Sodium-ion batteries, due to their abundant sodium resources, low cost, and environmental friendliness, have become an important supplement and alternative to lithium-ion batteries in the field of large-scale energy storage. Especially in the area of ​​anode-free design, by eliminating traditional anode active materials and directly using the current collector as a carrier for sodium deposition, the energy density of the battery can be significantly improved, making it one of the current research hotspots in sodium battery technology.

[0003] However, existing sodium-ion battery technology without a negative electrode still faces many challenges in practical applications. First, traditional negative electrode-free designs mostly rely on pouch cell structures, which have poor mechanical stability and require external clamps to maintain the cell shape. This not only increases the complexity and cost of the system, but also makes it prone to uneven pressure distribution leading to abnormal local sodium deposition, causing safety hazards such as sodium precipitation and dendrite growth.

[0004] Secondly, while prismatic batteries offer strong structural rigidity and require no additional clamps, they suffer from uneven internal mechanical stress distribution. Particularly during charging and discharging, changes in the gap between the electrode assembly and the casing exacerbate the unevenness of sodium deposition, impacting cycle life and safety. Furthermore, small cylindrical batteries, limited by size, have low active material filling rates, making it difficult to fully realize the high energy density potential of anode-free technology.

[0005] Regarding electrode structure, conventional single-tab or multi-tab designs tend to lead to uneven current density distribution, which in turn affects the deposition quality of sodium on the current collector surface and increases the risk of short circuits. At the same time, traditional steel casings are heavy and prone to electrolyte corrosion, further limiting the improvement of overall battery performance.

[0006] Therefore, the industry urgently needs a new type of battery structure that can break through the limitations of existing pouch, square and small cylindrical batteries, improve energy density, ensure the uniformity of sodium deposition and the structural stability of the battery, and promote the development of negative electrode-free sodium-ion batteries towards practical application and industrialization. Utility Model Content

[0007] The purpose of this patent is to provide a large cylindrical sodium-ion battery without negative electrode, which solves the problems of poor applicability, low energy density and uneven deposition of existing negative electrode batteries by using a large cylindrical all-aluminum structure, a full-tab design and a positive electrode winding process. This achieves high energy density, uniform sodium deposition and high safety.

[0008] To achieve the above objectives, this utility model provides the following technical solution: This utility model provides a sodium-ion battery with no negative electrode and full tabs, comprising: a large cylindrical all-aluminum casing, a battery cell assembly with full tabs and no negative electrode disposed within the casing, and a battery cover plate that cooperates with the casing; the battery cell assembly is formed by winding a positive electrode sheet, a separator, and a negative electrode current collector, and the positive electrode sheet has a pre-reserved empty foil area at the top to form a full tab structure; the inner wall of the casing is provided with a carbon coating, which is used as a negative electrode current collector for sodium deposition.

[0009] Preferably, the battery cell electrode assembly adopts a positive electrode end-to-end winding method, and the outermost layer is provided with a separator.

[0010] Preferably, the positive electrode sheet includes an aluminum foil current collector and a positive electrode active layer coated thereon, and the positive electrode active material includes NaxFeyPmOn, wherein 3≤x≤5, 2≤y≤4, 2≤m≤6, and 4≤n≤16.

[0011] Preferably, the negative electrode current collector is a carbon-coated aluminum foil with a thickness of 6-20 μm and a carbon layer thickness of 0.5-2 μm.

[0012] Preferably, the outer diameter of the outer shell is 36-56 mm and the wall thickness is 0.25-0.8 mm.

[0013] Preferably, the battery cover is equipped with an explosion-proof valve with an explosion-proof pressure of 1.4MPa to 1.8MPa.

[0014] Preferably, it also includes an aluminum current collector with a thickness of 0.2 to 0.4 mm, which is connected to the battery cell electrode assembly by laser welding.

[0015] Preferably, the carbon coating has a thickness of 6-20 μm and the material includes polyacrylic acid, deionized water, and a conductive agent.

[0016] Preferably, the height of the tab at the top of the positive electrode is 4-20 mm.

[0017] Preferably, the battery is a non-negative electrode sodium-ion battery, in which sodium is directly deposited on the inner wall of the outer casing or the surface of the negative electrode current collector during charging and discharging.

[0018] The beneficial effects of this utility model are as follows: This patent achieves significant benefits through the innovative integration of a large cylindrical all-aluminum structure, a full-tab design, and a positive electrode winding process. Firstly, the large cylindrical all-aluminum shell structure effectively balances internal mechanical stress, completely eliminating the reliance on soft-pack battery clamps and greatly expanding the application scenarios of negative electrode-free technology. Simultaneously, this structure significantly improves internal space utilization, resulting in a substantial increase in the proportion of active material. Combined with the innovative design of the aluminum shell inner wall as a sodium deposition carrier, it successfully achieves a leap in battery energy density and fundamentally avoids the corrosion problems of traditional steel shells. Secondly, the full-tab structure ensures uniform current distribution on the electrode plates, greatly improving the uniformity and density of sodium metal deposition on the negative electrode current collector, effectively suppressing sodium dendrite growth, and thus significantly reducing the risk of short circuits in the battery. Attached Figure Description

[0019] Figure 1 This is an exploded view of the overall structure of the sodium-electric cylindrical battery with all tabs and no negative electrode, according to this utility model. Figure 2 This is a schematic diagram showing the unfolded layered structure of the electrode assembly of the battery cell of this utility model; Figure 3 This is a schematic cross-sectional view of the winding structure of the electrode assembly of the battery cell of this utility model.

[0020] The attached diagram is described below: In the diagram: 1- Sealing pin; 2- Battery cover; 3- Positive current collector; 4- Cell electrode assembly; 5- Negative current collector; 6- Battery casing; 7- Negative current collector; 8- Separator; 9- Positive electrode sheet; 10- Positive electrode tab area; 11- Positive active material coating area; 12- Negative electrode tab area; 13- Negative electrode sodium deposition stripping area. Detailed Implementation

[0021] It should be noted that, without conflict, the embodiments and features in the embodiments of this utility model can be combined with each other.

[0022] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this utility model. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0023] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "fixed connection," and "fixed connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances. Example

[0024] This embodiment provides a sodium-ion battery with no negative electrode and a full-tabbed cylindrical structure, as shown below. Figure 1 and Figure 2 As shown. It mainly includes a battery cover plate 2, a positive current collector plate 3 and a negative current collector plate 5, a cell electrode assembly (wound core) 4, and a large cylindrical all-aluminum casing 6.

[0025] Positive electrode preparation: The positive electrode active material, conductive agent, and binder are mixed in N-methylpyrrolidone (NMP) solvent at a mass ratio of 96:2:2 and stirred until a uniform positive electrode slurry is formed. The positive electrode active material is NaFePO4F. The slurry is uniformly coated onto a 12μm thick aluminum foil current collector, and after drying, cold pressing, and slitting, a positive electrode sheet 9 is formed. An 8mm high empty foil area is reserved at the top of the positive electrode sheet as a full electrode tab (corresponding to...). Figure 1 10).

[0026] Negative current collector: Commercially available carbon-coated aluminum foil is directly used as the negative current collector 7, with an aluminum foil substrate thickness of 12μm and a surface carbon layer thickness of 1μm.

[0027] Diaphragm: A 16μm thick porous polyethylene diaphragm is selected.

[0028] Casing and Cover: The battery casing 6 is made of 3003 aluminum alloy, with an outer diameter of 46mm, a height of 80mm, and a wall thickness of 0.4mm. The inner wall of the casing 6 is coated with a 10μm thick carbon coating by spraying. The coating material consists of polyacrylic acid, deionized water, and Super P conductive agent. The battery cover 2 is equipped with an explosion-proof valve with an opening pressure of 1.6MPa. The current collectors 3 and 5 are made of 0.3mm thick aluminum discs.

[0029] The battery assembly process is as follows: Electrode winding: The positive electrode 9, separator 8, and carbon-coated aluminum foil 7 (serving as the negative electrode current collector) are stacked sequentially and wound in a "positive electrode beginning and end" manner. That is, the winding begins with the positive electrode and ends with the positive electrode on the outermost layer. An additional separator is then wound around the outermost layer to wrap the electrode, forming a structure resembling... Figure 2 The cylindrical battery cell electrode assembly 4 is shown.

[0030] Baking to remove moisture: Place the wound battery cell electrode assembly 4 in a vacuum oven and bake at 85°C for 24 hours to reduce the moisture content of the electrode assembly to below 300ppm.

[0031] Welded current collectors: Using laser welding technology, aluminum current collectors 3 and 5 are firmly welded to the positive and negative tabs of the cell electrode group 4, respectively, and insulating glue is wrapped around the contact point between the positive current collector and the edge of the electrode group for protection.

[0032] Housing insertion and welding: Push the welded current collector plate of the electrode assembly 4 into the aluminum alloy housing 6. Fasten the battery cover plate 2 to the opening of the housing 6, ensuring the positive electrode post on the cover plate faces outwards. Then, using laser welding, sequentially seal the bottom of the housing 6 to the negative current collector plate 5, the side wall of the housing 6 to the periphery of the cover plate 2, and the bottom of the recess inside the positive electrode post of the cover plate 2 to the positive current collector plate 3.

[0033] Electrolyte Injection and Sealing: A measured amount of electrolyte is injected into the battery through the injection hole on the positive electrode post of the cover plate 2. The electrolyte is a mixture of 1M NaPF6 dissolved in ethylene carbonate (EC) and diethyl carbonate (DEC) (volume ratio 1:1). Finally, the aluminum sealing nail 1 is placed into the recess at the injection hole and sealed using laser welding.

[0034] Formation and capacity testing: After sealing the battery, post-processing steps such as formation, aging and capacity testing are performed to activate the battery performance, thus obtaining the full-tab sodium-ion negative-maximum cylindrical battery.

[0035] During the first charge of the battery, sodium ions are released from the positive electrode active material, migrate through the electrolyte, and are uniformly deposited onto the carbon-coated aluminum foil 7 (which serves as the negative electrode current collector) and the carbon coating on the inner wall of the outer casing 6, forming a metallic sodium negative electrode. During discharge, the metallic sodium dissolves into sodium ions and migrates back to the positive electrode.

[0036] The large cylindrical all-aluminum structure (46mm diameter) provides excellent space utilization, enabling the battery to achieve a mass energy density of 280Wh / kg and a volumetric energy density of 580Wh / L.

[0037] The all-tab design, combined with the inner wall carbon coating, ensures extremely high current distribution uniformity. Testing showed that after 500 cycles at 1C, the battery retained 92% of its capacity, far exceeding the comparative example (75%), and exhibited no internal short circuits, demonstrating the high uniformity of sodium deposition and excellent cycle stability.

[0038] The process of combining the positive electrode with the outer diaphragm effectively utilizes the inner wall of the outer shell as an additional deposition area, further improving capacity and energy density, while avoiding the risk of short circuit due to direct contact between the outermost positive electrode of the electrode assembly and the aluminum shell.

[0039] The all-aluminum structure completely avoids the corrosion problem of steel shells and reduces weight by about 30%.

[0040] Comparative example: In contrast, using the exact same material system (positive electrode, electrolyte, etc.) and process, a traditional single-tab, steel-cased 18650 (18mm in diameter, 65mm in height) sodium-ion battery without a negative electrode was manufactured.

[0041] Test results show that, due to uneven current distribution and space limitations, the energy density (205Wh / kg, 420Wh / L) and cycle life (75% capacity retention after 500 cycles) of the comparative battery are significantly lower than those of the embodiments of the present invention.

[0042] In summary, this invention, through its large cylindrical all-aluminum structure, full-tab design, and innovative winding process, successfully provides a high-performance, high-safety, and long-life sodium-ion battery without a negative electrode, solving many bottleneck problems in existing technologies.

[0043] For those skilled in the art, several improvements and modifications can be made without departing from the principle of this utility model, and these improvements and modifications should also be considered within the scope of protection of this utility model.

Claims

1. A sodium-electric cylindrical battery with no negative electrode and full tabs, characterized in that, include: The large cylindrical all-aluminum casing (6), the full-tab battery cell assembly without negative electrode disposed inside the casing, and the battery cover plate (2) that cooperates with the casing; the battery cell assembly is formed by winding a positive electrode sheet, a separator and a negative electrode current collector, and the positive electrode sheet has a reserved empty foil area at the top to form a full-tab structure; the inner wall of the casing (6) is provided with a carbon coating, which is used as a negative electrode current collector for sodium deposition.

2. The sodium-electric cylindrical battery with no negative electrode diameter and full tabs according to claim 1, characterized in that, The battery cell electrode assembly adopts a positive electrode head-to-tail winding method, and the outermost layer is provided with a diaphragm (8).

3. The sodium-electric cylindrical battery with no negative electrode diameter and full tabs according to claim 1, characterized in that, The positive electrode sheet includes an aluminum foil current collector and a positive electrode active layer coated thereon, the positive electrode active layer including Na x Fe y P m O n , where 3≤x≤5, 2≤y≤4, 2≤m≤6, 4≤n≤16.

4. The sodium-electric cylindrical battery with no negative electrode diameter and full tabs according to claim 1, characterized in that, The negative electrode current collector is a carbon-coated aluminum foil with a thickness of 6-20 μm and a carbon layer thickness of 0.5-2 μm.

5. The sodium-electric cylindrical battery with no negative electrode diameter and full tabs according to claim 1, characterized in that, The outer diameter of the outer shell (6) is 36-56 mm and the wall thickness is 0.25-0.8 mm.

6. The sodium-electric cylindrical battery with no negative electrode diameter and full tabs according to claim 1, characterized in that, The battery cover (2) is equipped with an explosion-proof valve with an explosion-proof pressure of 1.4MPa to 1.8MPa.

7. The sodium-electric cylindrical battery with no negative electrode diameter and full tabs according to claim 1, characterized in that, It also includes an aluminum current collector with a thickness of 0.2 to 0.4 mm, which is connected to the battery cell electrode assembly by laser welding.

8. The sodium-electric cylindrical battery with no negative electrode diameter and full tabs according to claim 1, characterized in that, The height of the tab at the top of the positive electrode is 4-20mm.

9. The sodium-electric cylindrical battery with no negative electrode diameter and full tabs according to claim 1, characterized in that, The battery is a non-negative electrode sodium-ion battery, in which sodium is directly deposited on the inner wall of the outer casing or the surface of the negative electrode current collector during charging and discharging.

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