Pole piece, battery and battery pack

Abstract

The utility model relates to the field of battery pole pieces and batteries, particularly provides a pole piece, a battery and a battery pack, and aims to solve the problem that foil of the pole piece of the battery pack is broken due to the fact that a current collector is pulled due to thickness expansion of a battery cell. In order to achieve the purpose, the pole piece comprises a current collector, the current collector comprises a main body part and a tab part, the tab part is located at one end of the main body part in the length direction, and an electrode material layer is arranged on the surface of the main body part; in the length direction of the main body part, one part of the tab part is of a wave-shaped structure, the ratio of the length of the wave-shaped structure to the length of the tab part is 0.2-0.5, and the wave-shaped structure can elastically extend when being subjected to tension. According to the scheme, one part of the tab part of the current collector is arranged to be of the wave-shaped structure, so that the tab has a certain redundant length, the battery is expanded and thickened, the length of the tab can be expanded by virtue of the tensile force, and the current collector is prevented from being broken due to the tensile force on the tab.

Description

Technical Field

[0001] The utility model relates to the field of battery pole pieces and batteries, and specifically provides a pole piece, a battery and a battery pack. Background Art

[0002] The rapid development of new energy vehicles, large-scale energy storage and advanced consumer electronics has led to increasing requirements for the energy density of lithium-ion secondary batteries. In terms of power batteries, improving the energy density of batteries will not only help to increase the range of electric vehicles, but also effectively solve the current high cost problem.

[0003] There are many types of lithium batteries. Taking soft-pack batteries and square-shell laminated batteries as examples, multiple layers of positive and negative electrode sheets are stacked together, and then the collector foils of the multiple layers of positive and negative electrode sheets are welded to form pole ears, which serve as the positive and negative electrode drainage terminals of the battery cell. In the prior art, the internal arrangement of the battery cell is generally diaphragm-negative electrode-diaphragm-positive electrode-diaphragm-negative electrode-diaphragm-... (and so on). During the charge and discharge cycle of the battery cell, the negative electrode sheet expands, the overall thickness of the battery cell increases, and the current collector foil at both ends of the positive or negative electrode is pulled by the thickening of the material area, which may cause the current collector foil to break, thereby affecting the battery performance.

[0004] Accordingly, the art needs a new pole piece to solve the above problems. Utility Model Content

[0005] The utility model aims to solve the above technical problem, that is, to solve the problem in the prior art that the pole piece of the battery is pulled by the current collector pole tab due to the expansion of the battery core thickness, resulting in the breakage of the pole tab foil. To this end, the utility model provides a pole piece, which includes a current collector, the current collector includes a main body and a pole tab, the pole tab is located at one end of the main body in the length direction, and the surface of the main body is provided with an electrode material layer; in the length direction of the main body, a part of the pole tab is a wavy structure, the length of the wavy structure accounts for 0.2-0.5 of the length of the pole tab, and the wavy structure can be elastically stretched when subjected to tension.

[0006] In the above specific embodiment with the pole piece, the pole ear portion includes a first straight structure, the wavy structure and a second straight structure arranged in sequence along the length direction of the main body portion, and the first straight structure is close to the main body portion.

[0007] In the above specific implementation with pole pieces, the shape of the wavy structure is a sinusoidal waveform.

[0008] In the above specific implementation with the pole piece, the vertical distance h between the crest position and the trough position of the shape of the waveform structure is 0.1 mm-1 mm.

[0009] In the above specific embodiment with the pole piece, the length of the pole ear portion is 5 mm to 30 mm, and the ratio of the length of the pole ear portion in the length direction of the main body portion to the length of the main body portion is 0.01-0.1.

[0010] In the above-mentioned specific embodiment with a pole piece, the pole piece also includes a ceramic coating, which is arranged on the surface of the current collector located at the connection position between the main body and the pole ear portion, and the ceramic coating is arranged on the surface of the electrode material layer and the surface of the pole ear portion.

[0011] In the above specific embodiment with the pole piece, the corner where the pole ear portion is connected to the main body portion is in an arc shape.

[0012] In the above specific embodiment with a pole piece, a partial area of ​​the second flat structure includes a welding area.

[0013] A battery comprising a plurality of pole pieces according to any one of the above schemes.

[0014] A battery pack comprises the pole piece described in any one of the above schemes or the battery described in the above schemes.

[0015] In the case of adopting the above technical solution, the pole piece of the utility model makes structural improvements to the ear area of ​​the current collector, and the ear part of the current collector is partially designed as a wavy structure along the length direction of the main body, so that the length of the ear has a certain redundant length, so that the pole piece is in the battery, and the battery expands and thickens. Even if the current collector ear part of the pole piece is subjected to a certain tensile force, the ear forms a wavy structure and can also use the tensile force to expand the length, so as to avoid the ear of the current collector being unable to withstand the deformation caused by the tensile force due to the tensile force, resulting in the break of the current collector. When the ear in the prior art is subjected to a certain tensile force, within the range that the plastic deformation of the material itself can withstand, it can compensate for the dimensional changes caused by the thickening of the battery by deformation, but when the tensile force exceeds the range that the plastic deformation of the ear itself can withstand, it will tear or even break. Therefore, under the condition of large tensile force, the current collector ear part with a wavy structure can better withstand the tensile force without breaking, thereby effectively alleviating the harm caused by the battery expansion to the pulling and breaking of the current collector ear to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings, in which:

[0017] Figure 1 It is a schematic diagram of the top view of the pole piece in the utility model;

[0018] Figure 2It is a schematic diagram of the side view structure of the pole piece in the utility model, which shows a wavy structure;

[0019] Figure 3 for Figure 2 A partial enlarged view of the portion A in the middle, showing a wavy structure;

[0020] Figure 4 It is a schematic diagram of the battery structure of the utility model.

[0021] In the figure: 1. current collector, 2. main body, 3. ear part, 31. wavy structure, 32. first straight structure, 33. second straight structure, 4. electrode material layer, 5. ceramic coating, 6. corner, 7. welding area, 8. diaphragm, 9. positive electrode sheet, 10. negative electrode sheet. DETAILED DESCRIPTION

[0022] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not used to limit the protection scope of the present invention. Those skilled in the art can make adjustments to them as needed to adapt to specific application scenarios.

[0023] It should be noted that in the description of the present invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc. indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings, which are only for the convenience of description, and do not indicate or imply that the relevant devices or components must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, ordinal numbers such as "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0024] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installation" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] Furthermore, in order to more clearly demonstrate the core technical solution of the present utility model, the description of the well-known structure of the battery is omitted in the following description. However, this omission is only for the convenience of description and does not mean that the battery can be without these structures.

[0026] See also Figure 4In order to facilitate understanding of the defects of the current collector 1 of the electrode sheet in the prior art, the technical problem is described in combination with the battery. The battery is a multi-layer structure formed by packaging the electrode sheets. Specifically, the internal electrode sheets are formed by alternately stacking the positive electrode sheets 9, the negative electrode sheets 10 and the separator 8 in a certain stacking order. The positive electrode sheets 9 and the negative electrode sheets 10 have similar structural types. Both are coated with an electrode material layer 4 on the main body 2 of the current collector 1, at least on one side. The electrode ear 3 is adjacent to one end of the electrode material layer 4. A part of the electrode ear 3 is an empty foil area. When stacking, the separator 8-negative electrode sheet 10-separator 8-positive electrode sheet 9-separator 8-negative electrode sheet 10-separator 8... stacked according to such a rule, wherein the electrode ear 3 of multiple positive electrode sheets 9 is on one side, and the electrode ear 3 of multiple negative electrode sheets 10 is on the other side. The ends of the electrode ear 3 are welded to form a whole, and the battery is packaged.

[0027] During use, the negative electrode sheet 10 will expand due to charging and discharging or other situations, and the overall thickness of the battery will increase. Therefore, the end ear portions 3 of the positive electrode sheet 9 and the negative electrode sheet 10 will be pulled by the main body 2 coated with the electrode material layer 4, and the empty foil areas of multiple ear portions 3 will change in length due to the pulling force. When the pulling force exceeds the range that can be compensated by the plastic deformation of the material of the ear portion 3 itself, tearing will occur.

[0028] like Figure 1 and Figure 3 As shown, the utility model proposes a pole piece, which includes a current collector 1, and the current collector 1 includes a main body 2 and a pole ear 3, the pole ear 3 is located at one end of the main body 2 in the length direction, and an electrode material layer 4 is provided on the surface of the main body 2. Along the length direction of the main body 2, a part of the pole ear 3 is a wavy structure 31, and the wavy structure 31 can elastically stretch when subjected to tension.

[0029] In this embodiment, the proposed pole piece includes a current collector 1, wherein the current collector 1 includes a main body 2 with an electrode material layer 4 coated on the surface, and an empty foil area portion not coated with the electrode material layer 4, namely, a pole ear portion 3. The electrode material layer 4 portion can be selectively coated on the upper and lower large surfaces of the main body 2, and can be adaptively adjusted according to actual application requirements. The pole ear portion 3 is a structural portion with a width smaller than the main body 2 formed by cutting after the current collector 1 is coated with the electrode coating layer. Referring to the above-mentioned prior art description, after the battery is formed, multiple layers of pole ear portions 3 are stacked together and the ends are welded to form the pole ears of the battery. The utility model is aimed at improving the pole ear portion 3 of the pole piece. Considering that the pole ear portion 3 is torn or even broken due to the tension that cannot be withstood after the battery is used and expanded, the technical idea for solving the above-mentioned problem is to enhance the amount of elastic deformation that can occur in the pole ear portion 3 when subjected to tension, thereby overcoming the defect of tensile fracture.

[0030] Specifically, a portion of the pole ear portion 3 in the length direction of the main body portion 2 is designed as a wavy structure 31. The wavy structure 31 can elastically stretch when subjected to tension. The wavy structure 31 can allow the pole ear portion 3 to maintain a certain redundant length during the initial stacking process to form a battery. Then, when the battery becomes thicker after use, even if the pole ear is subjected to a large tensile force, the redundant length can be used to fill the length gap to avoid tearing or even breaking.

[0031] It should be noted that the wavy structure 31 of the pole ear portion 3 is designed to be wavy on the upper and lower surfaces of the pole ear portion 3. The specific waveform structure of the wavy structure 31 and the correspondence between the upper and lower crests and troughs can be flexibly selected. The wavy structure 31 can be a regular wavy structure 31, with the same amplitude of the crest and trough and a fixed period; it can also be an irregular wavy structure 31, with different amplitudes between the crest and trough, and different periods; as long as the pole ear portion 3 can have a certain redundant length, the wavy structure 31 can have a variety of optional structures without deviating from the technical concept of the utility model. Exemplarily, both sides of the pole ear portion 3 can be a zigzag wavy structure, the amplitude of the zigzag wave can be the same or different, and it can also be a curved wavy structure, which has a smoother transition than a zigzag wavy structure. Of course, this is not restrictive.

[0032] Furthermore, the wavy structures 31 on both sides of the pole ear portion 3 are preferably such that the wavy structures 31 on one side have the same waveform as the wavy structures 31 on the other side and are equidistant and parallel.

[0033] Through the above technical solution, the thickness of the pole ear portion 3 in the part forming the wavy structure 31 can be maintained to be the same at each location. Taking into account that the pole ear portion 3 is elastically deformed by tension, the wavy pole ears with the same thickness have more consistent properties and similar deformation capabilities. When subjected to tension, the pole ear portion 3 of the entire wavy structure 31 will slowly and gradually unfold, which can better adapt to the tension and avoid the situation where the redundant length of the pole ear portion 3 is unevenly unfolded due to local uneven force.

[0034] Furthermore, the pole ear portion 3 is provided with a first straight structure 32, a wavy structure 31 and a second straight structure 33 along the length direction of the main body portion 2, wherein the first straight structure 32 is on the side close to the main body portion 2 to form a transition area, and the second straight structure 33 is at the outer end of the pole ear portion 3, so as to facilitate the ends of the pole ear portions 3 of multiple pole pieces to be superimposed and welded together. Furthermore, in the length direction of the main body portion 2, the length of the wavy structure 31 accounts for 0.2 to 0.5 of the length of the pole ear portion 3.

[0035] Further, taking one specification of the pole piece as an example for description, the electrode material layer 4 on the surface of the main body 2 of the pole piece is selected with corresponding size as needed. In the length direction of the main body 2, the length of the pole ear 3 is 16 mm, the length of the first straight structure 32 is 1.25 mm, the length of the wavy structure 31 is 5.6 mm, and the length of the second straight structure is 6.65 mm. After the battery is formed, the wavy structure 31 is designed on the pole ear 3 to give the pole ear an extra redundant length to meet the use requirements.

[0036] In this embodiment, the wavy structure 31 of the pole ear portion 3 adopts a sinusoidal waveform. The sinusoidal waveform structure has a smooth transition, better force dispersion after being pulled, and can also avoid puncturing other parts. The coverage area of ​​the sinusoidal wavy structure 31 is less than or equal to the length of the entire empty foil area of ​​the pole ear portion 3, and the distance between the starting position of the wavy structure 31 and the main body 2 is ≥0.

[0037] On the basis of the above-mentioned embodiment, the sinusoidal wave-shaped structure 31 has multiple periods and multiple different amplitude options. The specific number of periods and amplitude can be flexibly selected according to the actual application. The number of periods and the amplitude are highly related to the size of the current collector 1. For the current collector 1 of the above-mentioned specifications, the number of periods can be 1-2, and the amplitude is 0.05mm-0.5mm. Flexible combination selection schemes can be selected according to needs.

[0038] It is conceivable that the length of the current collector 1 of the pole piece may have other dimensions, so the period and amplitude may also have different choices, but considering that the ear portion 3 of the current collector 1 can maintain a sufficient redundant length, the spacing between the peak and the trough should not be too large, see Figure 3 The vertical distance between the crest position and the trough position is h, and the value of the vertical distance h is 0.1mm-1mm, so that the pole ear part 3 can have sufficient redundant length.

[0039] On the basis of the above embodiment, the length of the current collector 1 of the pole piece can be 5mm to 30mm, and the distribution size ratio of the pole ear portion 3 and the main body 2 on the current collector 1 can be flexibly selected according to the needs of use, and needs to be set according to the specific situation. It can be imagined that when the thickness of the battery is relatively thick, the ratio of the length of the pole ear portion 3 to the length of the main body 2 will be larger, and when the thickness of the battery is relatively thin, the ratio of the length of the pole ear portion 3 to the length of the main body 2 will be smaller. The optional ratio of the length of the ear in the length direction of the main body 2 to the length of the main body 2 is 0.01-0.1.

[0040] Furthermore, the current collector 1 also includes a ceramic coating 5, which is arranged on the surface of the current collector 1 at the connection position between the main body 2 and the pole ear portion 3, and the ceramic coating 5 is arranged on the surface of the electrode material layer 4 and the surface of the pole ear portion 3. The ceramic coating 5 partially covers the electrode material layer 4 and partially covers the pole ear portion 3.

[0041] The ceramic coating 5 can play an insulating role. It is coated on the surface of the connection position between the main body 2 and the pole ear 3 to prevent the connection position between the main body 2 and the pole ear 3 of the pole piece from contacting the adjacent pole piece in extreme cases to cause a short circuit inside the battery. The ceramic coating 5 is preferably partially covered on the electrode material layer 4 and partially covered on the pole ear 3, so as to play a better protective role.

[0042] Furthermore, the pole pieces need to be stacked to form a battery, and the pole ears 3 at the ends need to be gathered and welded. Therefore, the pole ears 3 of the pole piece at the center position are shorter than the pole ears 3 on both sides. It should be noted that the length range does not limit the application of the improved points of the utility model, and other pole pieces beyond this range can also apply the technical solution of the utility model.

[0043] Based on the above embodiment, a partial area of ​​the second straight structure 33 can be used as a welding area 7, and the welding area 7 is at the end of the pole ear portion 3. When multiple pole pieces are stacked, the welding areas 7 of multiple pole ears 3 are superimposed together and welded to form a whole, which is then trimmed and cut to form a battery pole group.

[0044] Further, a circular arc structure transition is provided at the corner 6 where the lug portion 3 and the main body portion 2 are connected. For example, the arc transition is adopted to avoid stress concentration at the corner 6. The ceramic coating 5 covers the fillet of the corner. The ceramic coating 5 can strengthen the fillet area and improve the tear resistance of the corner 6 to a certain extent.

[0045] The utility model also proposes a battery, which includes multiple pole pieces and diaphragms 8 of any one of the above embodiments, the pole pieces are divided into positive pole pieces 9 and negative pole pieces 10, the diaphragm 8 is arranged between the positive pole pieces 9 and the negative pole pieces 10, the positive pole pieces 9 and the negative pole pieces 10 are alternately stacked, and the ends of the pole ears 3 of the positive pole pieces 9 and the negative pole pieces 10 are welded.

[0046] The utility model also provides a battery pack, which includes the pole piece of any one of the above embodiments or includes the battery provided in the above embodiments.

[0047] The battery pack in this embodiment can be a soft-pack battery or a square shell battery pack. The specific packaging method is selected according to the needs of use. Its internal electrode uses the electrode structure of the utility model. Therefore, the battery pack using the electrode with a wavy structure in the utility model should be considered to fall within the protection scope of the utility model.

[0048] So far, the technical solution of the present invention has been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A pole piece, characterized in that: The invention comprises a current collector (1), wherein the current collector (1) comprises a main body (2) and a pole ear (3), wherein the pole ear (3) is located at one end of the main body (2) in the length direction, and an electrode material layer (4) is provided on the surface of the main body (2); in the length direction of the main body (2), a part of the pole ear (3) is a wavy structure (31), the length of the wavy structure (31) accounts for a ratio of 0.2-0.5 of the length of the pole ear (3), and the wavy structure (31) can elastically stretch when subjected to tension.

2. The pole piece according to claim 1, characterized in that: The pole ear portion (3) comprises a first straight structure (32), the wavy structure (31) and a second straight structure (33) which are arranged in sequence along the length direction of the main body portion (2), wherein the first straight structure (32) is close to the main body portion (2).

3. The pole piece according to claim 2, characterized in that: The shape of the wavy structure (31) is a sine wave.

4. The pole piece according to claim 3, characterized in that: The vertical distance h between the wave crest position and the wave trough position of the wave-shaped structure (31) is 0.1 mm-1 mm.

5. The pole piece according to claim 1, characterized in that: The length of the pole ear portion (3) is 5 mm to 30 mm, and the ratio of the length of the pole ear portion (3) in the length direction of the main body portion (2) to the length of the main body portion (2) is 0.01-0.

1.

6. The pole piece according to claim 1, characterized in that: The pole piece further comprises a ceramic coating (5), wherein the ceramic coating (5) is arranged on the surface of the current collector (1) at the connection position between the main body (2) and the pole ear (3), and the ceramic coating (5) is arranged on the surface of the electrode material layer (4) and the surface of the pole ear (3).

7. The pole piece according to claim 1, characterized in that: The corner (6) at the connection between the pole ear portion (3) and the main body portion (2) is in an arc shape.

8. The pole piece according to claim 2, characterized in that: A partial area of ​​the second flat structure (33) includes a welding area (7).

9. A battery, characterized in that: The battery comprises a plurality of pole pieces according to any one of claims 1 to 8.

10. A battery pack, comprising the pole piece according to any one of claims 1 to 8 or the battery according to claim 9.

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