Electrode assembly and battery cell using the same

Abstract

The utility model relates to an electrode assembly, which is composed of a positive electrode sheet, a negative electrode sheet and a diaphragm. The electrode assembly is provided with a positive electrode ear and a negative electrode ear. The size of the negative electrode sheet is larger than that of the positive electrode sheet. The corners of the positive electrode sheet are inner arc angles. The corners of the negative electrode sheet are outer arc angles. The corners of the diaphragm are cut into inclined planes. The positive electrode sheet and the negative electrode sheet are stacked in sequence, and the diaphragm is provided between adjacent positive electrode sheets and negative electrode sheets. By designing the corners of the negative electrode sheet as outward arc angles and the corners of the positive electrode sheet as inward arc angles, the utility model effectively avoids the possibility of scratches on the aluminum-plastic film PP layer caused by the electrode sheet during stacking and packaging. This design improves the stacking method of the electrode sheets, reduces the possibility of physical interference, and also helps to reduce the loss during the battery assembly process.

Description

Technical Field

[0001] The utility model relates to an electrode assembly and a battery monomer adopting the electrode assembly. Background Art

[0002] As sodium-ion batteries are increasingly used in large-scale energy storage systems, the demand for the capacity and power of single cells is also increasing. In order to improve the efficiency of sodium batteries and reduce costs, the current trend is to reduce the number of parallel batteries when combining. Although sodium batteries currently exist in a variety of forms, including cylindrical, square aluminum shells and aluminum-plastic film soft packs, semi-solid and all-solid-state sodium batteries are mainly produced in soft pack form.

[0003] In the manufacturing process of soft-pack semi-solid and all-solid-state sodium batteries, the positive and negative electrodes are usually sliced ​​by direct cutting. However, this direct cutting method will cause interference between the bare battery cell and the aluminum-plastic film during assembly, and may even scratch the PP layer of the aluminum-plastic film.

[0004] To solve this problem, one way is to increase the size of the punch holes in the aluminum-plastic film, but doing so will result in a waste of battery cell space and reduce energy density.

[0005] Another solution is to innovate the shape of the pole piece to solve the problems of spatial interference and physical scratches. In addition, the chamfered arc of the positive and negative electrodes can be specially designed to avoid negative situations such as sodium or lithium precipitation caused by alignment differences, thereby improving the cycle life. Utility Model Content

[0006] The first object of the utility model is to provide an electrode assembly that can effectively reduce the occurrence of spatial interference and physical scratches and optimize the cycle life and energy density of the battery.

[0007] The second object of the utility model is to provide a battery cell that can effectively reduce the occurrence of spatial interference and physical scratches and optimize the cycle life and energy density of the battery.

[0008] The first purpose of the utility model is achieved in this way:

[0009] An electrode assembly, the electrode assembly is composed of a positive electrode sheet, a negative electrode sheet and a separator, the electrode assembly is provided with a positive electrode ear and a negative electrode ear, and the size of the negative electrode sheet is larger than that of the positive electrode sheet;

[0010] The corners of the positive electrode sheet are inner arc corners;

[0011] The corners of the negative electrode sheet are outer arc corners;

[0012] The corners of the diaphragm are cut into bevels;

[0013] The positive electrode sheets and the negative electrode sheets are stacked in sequence, and the separator is arranged between adjacent positive electrode sheets and negative electrode sheets.

[0014] Improved electrode sheet corner design: By designing the corners of the negative electrode sheet to be outward-facing arc angles and the corners of the positive electrode sheet to be inward-facing arc angles, the utility model effectively avoids the possibility of scratches on the aluminum-plastic film PP layer during the stacking and packaging of the electrode sheets. This design improves the stacking method of the electrode sheets, reduces the possibility of physical interference, and also helps to reduce losses during battery assembly.

[0015] Optimization of negative electrode sheet size: Ensuring that the negative electrode sheet is larger than the positive electrode sheet is another key design of the utility model. This design ensures that during the formation, capacity measurement and cycle stages of the battery, there are sufficient negative electrode locations for the sodium ions or lithium ions from the positive electrode to be embedded. This not only helps to achieve more efficient ion exchange, but also significantly reduces the generation of sodium or lithium dendrites caused by the boundary dislocation effect.

[0016] Improve battery cycle life: By optimizing the edge design of the electrode sheet and ensuring the size advantage of the negative electrode sheet, the utility model significantly improves the cycle life of the battery. These design considerations enable the battery to maintain high structural stability and chemical stability during repeated charge and discharge, thereby reducing performance degradation.

[0017] Improve energy density: Reasonable design reduces the necessary protection space and material usage, which helps to improve the energy density of the battery. Less material usage and higher energy density also mean cost optimization.

[0018] Wide applicability: Although the utility model is particularly applicable to sodium batteries, its design is also applicable to large-capacity single-cell lithium batteries. This ensures the wide applicability and practicality of the utility model in the battery manufacturing industry.

[0019] Solve the spatial interference problem: By beveling the corners of the diaphragm, the spatial interference caused by excess diaphragm material in the electrode stack is reduced. This design effectively optimizes the spatial layout of the electrodes and diaphragms, allowing the components inside the battery cell to be arranged more closely and neatly, reducing the internal structure mismatch caused by excess diaphragms.

[0020] Reduce pole piece extrusion: In the traditional battery manufacturing process, the mismatch between the diaphragm and the pole piece may cause the pole piece to be extruded during the assembly process, affecting the battery performance. The utility model ensures the pairing of the pole piece and the diaphragm by adjusting the size and shape of the diaphragm, thereby effectively reducing the pole piece extrusion and improving the structural stability and performance reliability of the battery cell.

[0021] The first purpose of the utility model can also be solved by the following technical measures:

[0022] Furthermore, the corners of the diaphragm are cut into 45° bevels.

[0023] The second purpose of the utility model is achieved in this way:

[0024] A battery cell also includes an aluminum-plastic film, which surrounds a positive electrode sheet, a negative electrode sheet and a separator and contains an electrolyte. The electrode assembly is provided with a positive electrode ear and a negative electrode ear, which extend out of the aluminum-plastic film respectively.

[0025] Improve the integrity and safety of battery packaging: Using aluminum-plastic film to encapsulate the positive electrode, negative electrode and separator can effectively isolate the external environment and prevent moisture and other harmful substances from penetrating into the battery, thereby reducing the risk of battery damage and improving the safety of battery use.

[0026] Enhance the chemical stability of the battery: The space inside the aluminum-plastic film is filled with electrolyte, which ensures effective contact between the electrode sheet and the electrolyte, promotes the rapid migration of ions, and enhances the electrochemical performance of the battery. In addition, the sealing properties of the aluminum-plastic film help maintain the stability of the electrolyte and prevent volatilization and leakage of the electrolyte.

[0027] Optimize the structural design of the battery: By setting the positive and negative tabs in the electrode assembly and extending them out of the aluminum-plastic film, it is convenient to connect the battery with the external circuit. This design not only simplifies the battery assembly process, but also improves the reliability and durability of the battery interface.

[0028] Extend battery life: The use of aluminum-plastic film reduces the physical loss and chemical corrosion of the internal components of the battery, which helps to extend the service life of the battery, especially in applications under high load or high temperature environments.

[0029] Improve the efficiency of bare cell pitting: Since the corners of the diaphragm are cut into bevels, the battery assembly process is greatly simplified, especially in the shelling operation of bare cells, which reduces the difficulty of operation and speeds up production. This design makes the production of large-capacity batteries more efficient, especially for large cells above 500Ah, the efficiency improvement is particularly significant.

[0030] Improved cell appearance: The optimized diaphragm design reduces the wrinkle problem that may be caused by improper stacking of pole pieces and diaphragms during battery packaging, thereby improving the appearance quality of the battery cell.

[0031] Improve production efficiency and reduce costs: The design of the utility model simplifies the battery assembly process, reduces errors and scrap rates in the production process, and improves overall production efficiency. At the same time, due to reduced material waste and reduced maintenance costs, the overall production cost is effectively controlled.

[0032] The second purpose of the utility model can also be solved by the following technical measures:

[0033] Furthermore, the electrolyte includes sodium hexafluorophosphate and an organic solvent.

[0034] Furthermore, the number of the positive electrode sheet is one less than that of the negative electrode sheet.

[0035] Reduced manufacturing costs: Reducing one positive electrode sheet can reduce the manufacturing cost of the battery. Positive electrodes usually contain rare metals or high-cost materials, while negative electrodes usually use more common materials. Therefore, reducing one positive electrode sheet can save material costs and reduce the manufacturing cost of the battery.

[0036] Improve energy efficiency: Optimizing the reaction balance between the positive and negative electrodes can improve the energy efficiency of the battery. One less positive electrode sheet than the negative electrode sheet may lead to a more appropriate positive and negative electrode reaction ratio, thereby improving the energy conversion efficiency of the battery and extending the battery life.

[0037] Furthermore, the separator is arranged outside the outermost negative electrode sheet.

[0038] Enhanced battery safety: Placing the separator outside the outermost negative electrode sheet can effectively isolate the positive and negative electrodes of the battery, reducing direct contact between the positive and negative electrodes and the possible short circuit risk. This can reduce the possibility of battery failure during use and improve battery safety.

[0039] Furthermore, the diaphragm is a single piece.

[0040] The beneficial effects of the utility model are as follows:

[0041] The utility model effectively avoids the possibility of scratching the aluminum-plastic film PP layer during the stacking and packaging of the electrode sheets by designing the corners of the negative electrode sheet to be outwardly arc-shaped and the corners of the positive electrode sheet to be inwardly arc-shaped. This design improves the stacking method of the electrode sheets, reduces the possibility of physical interference, and also helps to reduce the loss during the battery assembly process.

[0042] Another key design of the utility model is to ensure that the size of the negative electrode sheet is larger than that of the positive electrode sheet. This design ensures that during the formation, capacity measurement and cycle stages of the battery, the sodium ions or lithium ions from the positive electrode have sufficient negative electrode positions for them to be embedded. This not only helps to achieve more efficient ion exchange, but also significantly reduces the generation of sodium or lithium dendrites caused by the boundary dislocation effect.

[0043] The utility model significantly improves the cycle life of the battery by optimizing the edge design of the electrode sheet and ensuring the size advantage of the negative electrode sheet. These design considerations enable the battery to maintain high structural stability and chemical stability during repeated charge and discharge, thereby reducing performance degradation.

[0044] In the traditional battery manufacturing process, the mismatch between the diaphragm and the pole piece may cause the pole piece to be squeezed during the assembly process, affecting the battery performance. The utility model ensures the pairing of the pole piece and the diaphragm by adjusting the size and shape of the diaphragm, thereby effectively reducing the squeezing of the pole piece and improving the structural stability and performance reliability of the battery monomer. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 Schematic diagram of a positive electrode sheet in the prior art.

[0046] Figure 2 Schematic diagram of a negative electrode sheet in the prior art.

[0047] Figure 3 A schematic diagram of an electrode assembly according to the prior art.

[0048] Figure 4 A schematic diagram of a diaphragm according to the prior art.

[0049] Figure 5 The schematic diagram of the prior art is that the diaphragm is loaded with an aluminum-plastic film.

[0050] Figure 6 It is a schematic diagram of the positive electrode sheet of the utility model.

[0051] Figure 7 It is a schematic diagram of the negative electrode sheet of the utility model.

[0052] Figure 8 It is a schematic diagram of the electrode assembly of the present invention.

[0053] Fig. 9 It is a schematic diagram of the diaphragm of the utility model.

[0054] Fig.10 It is a schematic diagram of the diaphragm of the utility model being loaded with the aluminum-plastic film.

[0055] Fig.11 Schematic diagram of a battery cell.

[0056] Fig.12 Schematic diagram of the electrode assembly.

[0057] Fig.13 Schematic diagram of the combination of positive electrode sheet, negative electrode sheet and separator. DETAILED DESCRIPTION

[0058] The utility model is further described below in conjunction with the accompanying drawings and embodiments:

[0059] Example, combined with Figures 4 to 9 As shown, an electrode assembly 5, the electrode assembly 5 is composed of a positive electrode sheet 1, a negative electrode sheet 2 and a separator 3, and the electrode assembly 5 is provided with a positive electrode ear 11 and a negative electrode ear 12, characterized in that:

[0060] The size of the negative electrode sheet 2 is larger than that of the positive electrode sheet 1;

[0061] The corners of the positive electrode sheet 1 are inner arc corners 6;

[0062] The corners of the negative electrode sheet 2 are outer arc corners 7;

[0063] The corners of the diaphragm 3 are cut into bevels 31;

[0064] The positive electrode sheets 1 and the negative electrode sheets 2 are stacked in sequence, and the separator 3 is disposed between adjacent positive electrode sheets 1 and negative electrode sheets 2 .

[0065] Furthermore, the corners of the diaphragm 3 are cut into 45° inclined surfaces 31 .

[0066] A battery cell using the electrode assembly 5 also includes an aluminum-plastic film 4, which surrounds the positive electrode sheet 1, the negative electrode sheet 2 and the separator 3 and contains an electrolyte. The electrode assembly 5 is provided with a positive electrode ear 11 and a negative electrode ear 12, and the positive electrode ear 11 and the negative electrode ear 12 extend out of the aluminum-plastic film 4 respectively.

[0067] Furthermore, the electrolyte includes sodium hexafluorophosphate and an organic solvent.

[0068] Furthermore, the number of the positive electrode sheet 1 is less than that of the negative electrode sheet 2 .

[0069] Furthermore, the separator 3 is arranged outside the outermost negative electrode sheet 2 .

[0070] Furthermore, the diaphragm 3 is a single piece.

[0071] Made into BT120888699, capacity 600Ah, top head length 1200mm, of which the main part is 888mm, the airbag part is 318mm, and the width is 10mm.

[0072] The size of the positive electrode sheet 1 is: 876mm (W) * 663mm (L) with four inner corners in arc shape.

[0073] The size of the negative electrode sheet 2 is: 880mm (W) * 667mm (L), with four corners in an arc shape.

[0074] The size of the diaphragm 3 is 886*674 mm, and the corners of the diaphragm 3 are cut into bevels 31.

[0075] The corners of the positive and negative electrodes are stacked in right angles and arc angles, and the tests are shown in the following table.

[0076]

[0077] The corners of the diaphragm are made of right angles and bevels, and the tests are shown in the following table.

[0078] Case This utility model patented product Existing technology (such as Figures 1 to 5 ) Aluminum plastic film 4 damage rate 0.0008％ 0.005％ Corner wrinkle rate 0.009％ 0.010％ Repair rate 2.5PPM 0.01％

Claims

1. An electrode assembly, the electrode assembly (5) comprising a positive electrode sheet (1), a negative electrode sheet (2) and a separator (3), the electrode assembly (5) being provided with a positive electrode tab (11) and a negative electrode tab (12), characterized in that: The size of the negative electrode sheet (2) is larger than that of the positive electrode sheet (1); The corners of the positive electrode sheet (1) are inner arc corners (6); The corners of the negative electrode sheet (2) are outer arc corners (7); The corners of the diaphragm (3) are cut into bevels (31); The positive electrode sheets (1) and the negative electrode sheets (2) are stacked in sequence, and the separator (3) is provided between adjacent positive electrode sheets (1) and negative electrode sheets (2).

2. The electrode assembly according to claim 1, characterized in that: The corners of the diaphragm (3) are cut into 45° inclined surfaces (31).

3. A battery cell using the electrode assembly as claimed in claim 1, characterized in that: The device further comprises an aluminum-plastic film (4), wherein the aluminum-plastic film (4) surrounds the positive electrode sheet (1), the negative electrode sheet (2) and the separator (3), and an electrolyte is arranged in the aluminum-plastic film (4); the electrode assembly (5) is provided with a positive electrode ear (11) and a negative electrode ear (12), and the positive electrode ear (11) and the negative electrode ear (12) respectively extend out of the aluminum-plastic film (4).

4. The battery cell according to claim 3, characterized in that: The electrolyte includes sodium hexafluorophosphate and an organic solvent.

5. The battery cell according to claim 3, characterized in that: The number of the positive electrode sheet (1) is one less than that of the negative electrode sheet (2).

6. The battery cell according to claim 3, characterized in that: The separator (3) is arranged outside the outermost negative electrode sheet (2).

7. The battery cell according to claim 3, characterized in that: The diaphragm (3) is a single piece.

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