Winding battery cell

Abstract

The utility model relates to a winding battery cell which comprises a straight part positioned in the middle and bent parts positioned at two ends of the straight part, a positive plate and a negative plate positioned at the straight part respectively contain positive electrode powder and negative electrode powder, and the positive plate and the negative plate positioned at the bent parts do not contain the positive electrode powder and the negative electrode powder. Compared with the prior art, only the positive plate and the negative plate which are positioned on the straight parts of the winding battery cell provided by the utility model contain the positive powder and the negative powder, and the positive plate and the negative plate which are positioned on the bent parts do not contain the positive powder and the negative powder, so that an electrochemical reaction only occurs between the positive plate and the negative plate which are positioned on the straight parts; when the battery cell is charged and discharged, stress is generated only by volume change of the positive plate and the negative plate of the straight part, the stress is uniformly distributed, and the bending part does not generate a stress concentration phenomenon; the wound battery cell can be produced by adopting a conventional battery cell winding method, achieves the cycle performance and the safety performance of a laminated battery cell, and has the advantages of the conventional wound battery cell and the laminated battery cell at the same time.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, in particular to a wound battery core. Background Art

[0002] Power batteries are the power source for tools, mostly referring to batteries that power electric cars, electric trains, electric bicycles, and golf carts. Power batteries are the core components of new energy vehicles and an important direction for future energy transformation.

[0003] There are generally two types of cell structures for existing power batteries: wound structure and stacked structure. The wound structure has the advantages of low production difficulty, low cost, and high production capacity. However, due to the defects of rounded corners, inconsistent tension between the front and side surfaces, uneven internal electrochemical reaction rates, and the difference in rebound between the side and front electrodes, the core is prone to deformation and excessive thickness after cycling. Stress concentration is easily generated at the corners, which in turn causes the electrode of the cell to twist and the cell to bend and deform, greatly weakening the cycle performance and safety performance of the winding process.

[0004] The laminated structure does not have the problems of the winding structure mentioned above. After lamination, each layer of the pole piece is evenly stressed, the structure is more stable, the battery is not easily deformed, and the cycle performance is better. However, there are problems such as large equipment investment and low production capacity. Utility Model Content

[0005] In view of this, it is necessary to provide a wound battery cell to solve the technical problem in the prior art that the wound battery cell is prone to stress concentration at the corners due to the uneven internal electrochemical reaction rate, which leads to cell distortion and weakens the cycle performance and safety performance of the battery cell.

[0006] The utility model provides a wound battery core, which comprises: a straight portion in the middle and curved portions at both ends of the straight portion, wherein the positive electrode sheet and the negative electrode sheet at the straight portion contain positive electrode powder and negative electrode powder respectively, and the positive electrode sheet and the negative electrode sheet at the curved portion do not contain positive electrode powder and negative electrode powder.

[0007] Furthermore, the positive electrode sheet located at the straight portion and the positive electrode sheet located at the curved portion are connected end to end in sequence.

[0008] Furthermore, the negative electrode sheet located at the straight portion and the negative electrode sheet located at the curved portion are connected end to end in sequence.

[0009] Furthermore, it includes a separator, a positive electrode sheet and a negative electrode sheet, the positive electrode sheets and the negative electrode sheets are arranged alternately, and the separator is arranged between the positive electrode sheet and the negative electrode sheet.

[0010] Furthermore, the positive electrode sheet, the negative electrode sheet and the separator are rolled together to form a wound battery cell, and the cross section of the wound battery cell is a rounded rectangle, the middle part is a straight part, and the two ends are curved parts.

[0011] Furthermore, the positive electrode sheet, the negative electrode sheet and the isolation film located in the straight portion are arranged in parallel.

[0012] Furthermore, the positive electrode is aluminum foil.

[0013] Furthermore, the negative electrode sheet is copper foil.

[0014] Furthermore, the positive electrode powder is one or more of lithium iron phosphate, lithium cobalt oxide, and lithium manganese oxide.

[0015] Furthermore, the negative electrode powder is graphite.

[0016] Compared with the prior art, in the wound battery cell provided by the present invention, only the positive electrode sheet and the negative electrode sheet located in the straight part contain positive electrode powder and negative electrode powder, and the positive electrode sheet and the negative electrode sheet located in the curved part do not contain positive electrode powder and negative electrode powder, so that the electrochemical reaction only occurs between the positive electrode sheet and the negative electrode sheet located in the straight part, and no electrochemical reaction occurs between the positive electrode sheet and the negative electrode sheet located in the curved part, which only play a conductive role; when the battery cell is charged and discharged, only the volume change of the positive electrode sheet and the negative electrode sheet in the straight part generates stress, and the stress is evenly distributed, and no stress concentration phenomenon occurs in the curved part; the present wound battery cell can be produced by the conventional winding battery cell method, but achieves the cycle performance and safety performance of the laminated battery cell, and has the advantages of the conventional wound battery cell and the laminated battery cell.

[0017] The above description is only an overview of the technical solution of the utility model. In order to more clearly understand the technical means of the utility model and implement it according to the contents of the specification, the preferred embodiment of the utility model is described in detail as follows with the accompanying drawings. The specific implementation method of the utility model is given in detail by the following embodiments and their drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

[0019] Figure 1 This is a schematic structural diagram of an embodiment of a wound battery cell provided by the utility model. DETAILED DESCRIPTION

[0020] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0021] See also Figure 1The utility model provides a wound battery cell. The wound battery cell can be applied to power batteries or other types of batteries.

[0022] The wound battery cell includes a straight portion 1 in the middle and curved portions 2 at both ends of the straight portion 1. The positive electrode sheet 3A and the negative electrode sheet 4A located in the straight portion 1 contain positive electrode powder and negative electrode powder respectively, and the positive electrode sheet 3B and the negative electrode sheet 4B located in the curved portion 2 do not contain positive electrode powder and negative electrode powder.

[0023] Since only the positive electrode sheet 3A and the negative electrode sheet 4A located in the straight part 1 contain positive electrode powder and negative electrode powder, and the positive electrode sheet 3B and the negative electrode sheet 4B located in the curved part 2 do not contain positive electrode powder and negative electrode powder. The electrochemical reaction only occurs between the positive electrode sheet 3A and the negative electrode sheet 4A located in the straight part 1, and no electrochemical reaction occurs between the positive electrode sheet 3B and the negative electrode sheet 4B located in the curved part 2, and only plays a conductive role. When the battery cell is charged and discharged, only the volume change of the positive electrode sheet 3A and the negative electrode sheet 4A in the straight part 1 produces stress, and since the positive electrode sheet 3A and the negative electrode sheet 4A are straight, the volume increases or decreases uniformly at various places, and the generated stress is evenly distributed. However, no electrochemical reaction occurs in the curved part 2, and the positive electrode sheet 3B and the negative electrode sheet 4B do not produce volume changes, so naturally no stress concentration phenomenon will occur. Therefore, the cycle performance and safety performance of this wound battery cell are the same as those of the laminated battery cell, which is significantly better than the existing conventional wound battery cell.

[0024] In a preferred embodiment, the positive electrode sheet 3A located at the straight portion 1 and the positive electrode sheet 3B located at the curved portion 2 are connected end to end in sequence. Compared with the traditional laminated battery cell, this structure actually forms a positive electrode sheet because the positive electrode sheet 3A at the straight portion 1 and the positive electrode sheet 3B at the curved portion 2 are connected together. The cross-sectional area of ​​the positive electrode sheet is larger, the internal resistance is smaller, and the rate performance of the battery is improved.

[0025] Similarly, the negative electrode sheet 4A located in the straight portion 1 and the negative electrode sheet 4B located in the curved portion 2 are connected end to end in sequence to form a larger negative electrode sheet. By increasing the cross-sectional area of ​​the negative electrode sheet and reducing the internal resistance, the rate performance of the battery can be improved.

[0026] In this embodiment, the wound battery cell includes a separator 5, a positive electrode sheet and a negative electrode sheet. The positive electrode sheets and the negative electrode sheets are arranged alternately. The separator 5 is arranged between the positive electrode sheet and the negative electrode sheet to separate the positive electrode sheet from the negative electrode sheet.

[0027] The wound cell can be produced by a conventional wound cell method, that is, the positive electrode sheet, the negative electrode sheet and the separator 5 are wound together to form a wound cell, and the cross section of the wound cell is a rounded rectangle, the middle of which is a straight portion 1 and the two ends of which are curved portions 2. In this embodiment, the positive electrode sheet 3A, the negative electrode sheet 3B and the separator 5 located in the straight portion 1 are arranged in parallel.

[0028] This wound battery cell not only has the advantages of low production difficulty, low cost and high production capacity of traditional wound batteries, but also has the same excellent cycle performance and safety performance as laminated batteries. The rate performance can also surpass laminated batteries and reach the level of traditional wound batteries.

[0029] In this embodiment, the positive electrode sheet is made of aluminum foil, and the negative electrode sheet is made of copper foil. In other embodiments, other materials can also be used as long as they meet the electrochemical requirements.

[0030] In this embodiment, the positive electrode powder is one or more of lithium iron phosphate, lithium cobalt oxide, and lithium manganese oxide. The negative electrode powder is graphite. In other embodiments, other materials can also be used as long as they meet the electrochemical requirements.

[0031] Compared with the prior art, in the wound battery cell provided by the present invention, only the positive electrode sheet and the negative electrode sheet located in the straight part contain positive electrode powder and negative electrode powder, and the positive electrode sheet and the negative electrode sheet located in the curved part do not contain positive electrode powder and negative electrode powder, so that the electrochemical reaction only occurs between the positive electrode sheet and the negative electrode sheet located in the straight part, and no electrochemical reaction occurs between the positive electrode sheet and the negative electrode sheet located in the curved part, which only play a conductive role; when the battery cell is charged and discharged, only the volume change of the positive electrode sheet and the negative electrode sheet in the straight part generates stress, and the stress is evenly distributed, and no stress concentration phenomenon occurs in the curved part; the present wound battery cell can be produced by the conventional winding battery cell method, but achieves the cycle performance and safety performance of the laminated battery cell, and has the advantages of the conventional wound battery cell and the laminated battery cell.

[0032] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the present invention should be included in the protection scope of the present invention.

Claims

1. A wound battery cell, characterized in that: It includes: a straight portion in the middle and curved portions at both ends of the straight portion, the positive electrode sheet and the negative electrode sheet located in the straight portion contain positive electrode powder and negative electrode powder respectively, and the positive electrode sheet and the negative electrode sheet located in the curved portion do not contain positive electrode powder and negative electrode powder.

2. The wound battery cell according to claim 1, characterized in that: The positive electrode sheet located at the straight portion is connected end to end with the positive electrode sheet located at the curved portion.

3. The wound battery cell according to claim 1, characterized in that: The negative electrode sheet located at the straight portion is connected end to end with the negative electrode sheet located at the curved portion.

4. The wound battery cell according to claim 1, characterized in that: The invention comprises a separator, the positive electrode sheet and the negative electrode sheet. The positive electrode sheet and the negative electrode sheet are arranged alternately, and the separator is arranged between the positive electrode sheet and the negative electrode sheet.

5. The wound battery cell according to claim 4, characterized in that: The positive electrode sheet, the negative electrode sheet and the isolation film are rolled together to form the wound battery cell. The cross section of the wound battery cell is a rounded rectangle, the middle of which is the straight portion and the two ends of which are the curved portions.

6. The wound battery cell according to claim 5, characterized in that: The positive electrode sheet, the negative electrode sheet and the isolation film located in the straight portion are arranged in parallel.

7. The wound battery cell according to claim 1, characterized in that: The positive electrode sheet is aluminum foil.

8. The wound battery cell according to claim 1, characterized in that: The negative electrode sheet is copper foil.

9. The wound battery cell according to claim 1, characterized in that: The positive electrode powder is one or more of lithium iron phosphate, lithium cobalt oxide, and lithium manganese oxide.

10. The wound battery cell according to claim 1, characterized in that: The negative electrode powder is graphite.

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