Battery pole piece and battery cell

Abstract

The embodiment of the utility model provides a battery pole piece and a battery cell, and relates to the technical field of batteries. The battery pole piece comprises a base body layer, an electrode layer and a thinning layer, wherein the electrode layer covers the surface of the base body layer; the thinning layers are located at the two ends of the electrode layer, and the thickness of the thinning layers is smaller than that of the electrode layer. The two ends of the electrode layer are further provided with the thinning layers, and the thickness of the thinning layers is smaller than that of the electrode layer, so that the situation that when the battery pole piece is rewound, the edge of the battery pole piece bulges due to the fact that the edge thickness is larger than the thickness of the electrode layer, winding cannot be carried out, the flatness of the battery pole piece is reduced, and the performance of the battery pole piece is affected can be prevented.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, and in particular, to a battery electrode sheet and an electric core. Background Art

[0002] The core function of a battery electrode sheet is to convert chemical energy into electrical energy. In a battery, an energy difference, i.e., electromotive force, is generated when two different chemical substances interact. As an important part of the battery, the electrode converts its chemical energy into electrical energy and drives an electric current through an external circuit, thereby realizing the transmission and use of electrical energy.

[0003] However, currently, the electrode sheets of secondary batteries are mostly completed by a process route of homogenization - slurry coating - drying. The slurry itself belongs to Newtonian fluid and has good fluidity. During the coating process, due to the rheological properties of the slurry, coating edge bulging will occur, and the edge height is higher than the thickness of the large surface of the electrode sheet. During the winding step in the processing of the electrode sheet, it is easy to cause non - winding due to bulging, and the flatness of the electrode sheet will decrease, affecting the interface of the electrode sheet. If the edge thickness is large, when assembled into an electric core, uneven hot pressing and inconsistent electrode interfaces will also occur due to inconsistent coating thickness of the electrode sheet, ultimately affecting the overall performance of the electric core. Summary of the Utility Model

[0004] The utility model provides a battery electrode sheet and an electric core, which can improve the bulging of the electrode sheet.

[0005] The embodiments of the utility model can be implemented as follows:

[0006] The embodiments of the utility model provide a battery electrode sheet, which includes:

[0007] A substrate layer;

[0008] An electrode layer, which covers the surface of the substrate layer;

[0009] A thinning layer, which is located at both ends of the electrode layer, and the thickness of the thinning layer is less than the thickness of the electrode layer.

[0010] In an optional embodiment, the electrode layer includes a first electrode layer and a second electrode layer. The first electrode layer covers the upper surface of the substrate layer, and the second electrode layer covers the lower surface of the substrate layer; the length of the second electrode layer is less than the length of the first electrode layer; the first electrode layer and the second electrode layer are arranged in a staggered manner.

[0011] In an alternative embodiment, the tapered layer includes a first tapered layer and a second tapered layer. The first tapered layer is located at both ends of the first electrode layer, and the thickness of the first tapered layer is less than the thickness of the first electrode layer. The second tapered layer is located at both ends of the second electrode layer, and the thickness of the second tapered layer is less than the thickness of the second electrode layer.

[0012] For the first tapered layer and the second tapered layer located at the same end of the electrode layer, the distance between the end of the second tapered layer away from the second electrode layer and the end of the first tapered layer away from the first electrode layer in the extending direction of the substrate layer is 0 to 0.6 mm.

[0013] In an alternative embodiment, the length of the tapered layer is 1 mm to 6 mm.

[0014] In an alternative embodiment, the end of the electrode layer is connected to the substrate layer through a first rounded corner.

[0015] In an alternative embodiment, the radius of the first rounded corner is 0.4 mm to 6 mm.

[0016] In an alternative embodiment, the end of the tapered layer away from the electrode layer is connected to the substrate layer through a second rounded corner.

[0017] In an alternative embodiment, the radius of the second rounded corner is 1 mm to 5 mm.

[0018] In an alternative embodiment, the ratio of the thickness of the tapered layer to the thickness of the electrode layer is less than or equal to two-thirds and greater than or equal to one-sixth.

[0019] An embodiment of the present invention further provides an electric core, including the battery electrode sheet in any of the above embodiments.

[0020] The beneficial effects of the battery electrode sheet and the electric core in the embodiments of the present invention include:

[0021] The battery electrode sheet includes a substrate layer, an electrode layer, and a tapered layer. The electrode layer covers the surface of the substrate layer. The tapered layer is located at both ends of the electrode layer, and the thickness of the tapered layer is less than the thickness of the electrode layer. By providing a tapered layer at both ends of the electrode layer and making the thickness of the tapered layer less than the thickness of the electrode layer, it is possible to prevent the battery electrode sheet from bulging at the edges due to the edge thickness being higher than the thickness of the electrode layer during rewinding, resulting in inability to rewind, thereby causing a decrease in the flatness of the battery electrode sheet and further affecting the performance of the battery electrode sheet. Description of the Drawings

[0022] To more clearly illustrate the technical solutions of the embodiments of the present utility model, the accompanying drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following accompanying drawings only show some embodiments of the present utility model and should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other relevant accompanying drawings can also be obtained based on these drawings.

[0023] Figure 1 Schematic diagram of the first battery electrode plate provided in the embodiments of the present utility model;

[0024] Figure 2 Schematic diagram of the second battery electrode plate provided in the embodiments of the present utility model.

[0025] Icon: 1000 - battery electrode plate; 100 - matrix layer; 200 - electrode layer; 210 - first electrode layer; 220 - second electrode layer; 230 - first rounded corner; 300 - thinning layer; 310 - first thinning layer; 320 - second thinning layer; 330 - second rounded corner. Detailed implementation manners

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are some, but not all, of the embodiments of the present utility model. Usually, the components of the embodiments of the present utility model described and shown in the accompanying drawings here can be arranged and designed in various different configurations.

[0027] Therefore, the following detailed description of the embodiments of the present utility model provided in the accompanying drawings is not intended to limit the scope of the claimed present utility model, but merely represents the selected embodiments of the present utility model. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present utility model.

[0028] It should be noted that similar reference numerals and letters indicate similar items in the following accompanying drawings. Therefore, once an item is defined in one accompanying drawing, it does not need to be further defined and explained in subsequent accompanying drawings.

[0029] In the description of the present utility model, it should be noted that if terms such as "upper", "lower", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present utility model is habitually placed during use, 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 component 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.

[0030] In addition, if terms such as "first", "second", etc. are only used for distinguishing descriptions, they cannot be understood as indicating or implying relative importance.

[0031] It should be noted that, without conflict, the features in the embodiments of the present utility model can be combined with each other.

[0032] The core function of the battery electrode is to convert chemical energy into electrical energy. In a battery, the interaction between two different chemical substances generates an energy difference, i.e., electromotive force. As an important part of the battery, the electrode converts its chemical energy into electrical energy and drives the current through an external circuit, thereby realizing the transmission and use of electrical energy. However, currently, the electrodes of secondary batteries mostly adopt a process route of homogenization - slurry coating - drying. The slurry itself belongs to Newtonian fluid and has good fluidity. During the coating process, due to the rheological characteristics of the slurry, the coating edge bulges, and the edge height is higher than the thickness of the large surface of the electrode. During the winding step in the processing of the electrode, it is easy to cause non-winding due to the bulging edge, and it also causes a decrease in the flatness of the electrode, affecting the interface of the electrode. If the edge thickness is relatively large when assembling into a battery cell, it will also occur that the electrodes have uneven coating thickness, resulting in uneven hot pressing of the electrodes and inconsistent electrode interfaces, ultimately affecting the overall performance of the battery cell.

[0033] Based on this, please refer to Figure 1 and Figure 2 , the battery electrode 1000 provided in the embodiments of the present utility model can effectively improve the above-mentioned technical problem. The battery electrode 1000 improves the problem of the bulging edge of the battery electrode 1000, thereby ensuring the flatness of the finally formed battery electrode 1000 and ensuring the performance of the battery electrode 1000. The battery electrode 1000 is applied to a battery cell, the battery cell can be applied to a battery module, and the battery module can be used in an electric device, such as an electric vehicle and other devices. The battery cell, battery module, and battery device having the battery electrode 1000 all have the same functions as the battery electrode 1000, which will not be elaborated here.

[0034] The battery cell (not shown in the figure) in this embodiment includes a positive electrode plate, a negative electrode plate, a separator, an electrolyte, and a casing. The separator is disposed between the positive electrode plate and the negative electrode plate, and the casing wraps the positive electrode plate, the negative electrode plate, the separator, and the electrolyte. The main function of the separator is to prevent direct contact between the positive and negative electrodes, avoid short circuits, and at the same time allow ions to pass through to maintain the normal operation of the battery. The electrolyte is a liquid inside the battery, which provides a medium for ion transport, enabling the battery to perform charge and discharge reactions. The electrolyte is usually composed of an organic solvent and a lithium salt, such as lithium hexafluorophosphate, etc. The casing wraps the other components of the battery cell, playing a role in protecting the internal structure and preventing electrolyte leakage. The casing can be an aluminum casing or a steel casing, etc., which is not limited herein. Of course, for different types of battery cells, such as liquid lithium-ion batteries and polymer battery cells, their structures will be different. For example, the electrolyte surrounds the positive and negative electrodes of a liquid lithium-ion battery, while a polymer battery cell uses a polymer electrolyte to replace the liquid electrolyte. Therefore, the structures of different types of battery cells are also different. Therefore, the composition structure of the battery cell is determined according to the actual situation, which is not limited herein. The positive electrode plate and the negative electrode plate in the battery cell are the battery electrode plate 1000 in this embodiment, and the battery cell having the battery electrode plate 1000 also has the advantages of improving the problem of the edge bulging of the electrode plate and ensuring the battery performance.

[0035] Multiple battery cells connected in series and parallel can form a battery module. In addition to including multiple battery cells, the battery module may also include a casing, a battery management system, etc. According to actual practical requirements, the battery module may also include structures such as a liquid cooling system to achieve various functions of the battery module, which is not limited herein. The battery module having the above battery cell also has the advantages of improving the problem of the edge bulging of the electrode plate and ensuring the battery performance.

[0036] The structure of the battery electrode plate 1000 will be introduced in detail below.

[0037] Figure 1 It is a schematic diagram of the first battery electrode plate 1000 provided in the embodiment of the present invention; Figure 2 It is a schematic diagram of the second battery electrode plate 1000 provided in the embodiment of the present invention. As Figure 1 and Figure 2 shown, the battery electrode plate 1000 in this embodiment includes a substrate layer 100, an electrode layer 200, and a thinning layer 300. The electrode layer 200 covers the surface of the substrate layer 100; the thinning layer 300 is located at both ends of the electrode layer 200, and the thickness of the thinning layer 300 is less than the thickness of the electrode layer 200. By further providing the thinning layer 300 at both ends of the electrode layer 200, and the thickness of the thinning layer 300 is less than the thickness of the electrode layer 200, it is possible to prevent the battery electrode plate 1000 from bulging at the edges due to the edge thickness being higher than the thickness of the electrode layer 200 during rewinding, resulting in inability to rewind, thereby causing a decrease in the flatness of the battery electrode plate 1000, and further affecting the performance of the battery electrode plate 1000.

[0038] Specifically, the substrate layer 100 in this embodiment is the current collector layer. The main function of the current collector is to collect current, gathering the current generated by the battery active material to form a larger current for external output, thereby completing the conversion process of chemical energy into electrical energy. By making full contact with the battery active material, the current collector effectively collects current, enabling the battery to output a larger current externally, thereby improving the output power and efficiency of the battery. Usually, the substrate layer 100 of the positive electrode plate generally uses aluminum foil, and the substrate layer 100 of the negative electrode plate generally uses copper foil. Both copper foil and aluminum foil are metal materials, having good electrical conductivity and being relatively soft, which are suitable for preparing the electrode plates of the battery. In addition, copper foil and aluminum foil have relatively low prices and low production costs. Copper is relatively stable in air and not easily undergoes chemical reactions; aluminum will form a dense oxide film in air, which can protect the surface of aluminum and play a certain protective role in the electrolyte. The positive electrode potential of a lithium battery is relatively high, and using aluminum foil as the positive electrode current collector can remain stable at a high potential, while copper foil is easily oxidized at a high potential. Therefore, aluminum foil is generally used for the positive electrode and copper foil for the negative electrode to ensure the stability of the battery.

[0039] The electrode layer 200 is a positive electrode active material layer or a negative electrode active material layer. The positive electrode active material layer is usually composed of metal oxides or multiphase compounds, which can embed or extract ions during the charge and discharge process, thereby participating in the battery reaction. Common positive electrode active materials include lithium iron phosphate, lithium nickel cobalt manganese oxide, etc. The negative electrode active material layer is usually composed of carbon materials. Carbon materials have good electrical conductivity and stability, can embed or extract lithium ions, and participate in the battery reaction.

[0040] The thinning layer 300 in this embodiment is made of alumina. Since alumina is used together with an adhesive as a coating material, it can effectively play a mediating role. The structure of alumina is a plate-like crystal structure. When encountering a large current, the material will heat up, causing the volume of the plate-like crystal structure coating material of alumina to expand, thereby closing the current conduction holes on the lithium battery separator and playing a role in blocking the current. When the temperature drops, the material volume shrinks, and the current conduction holes on the barrier film are reopened. Utilizing the special physical and chemical properties of alumina can greatly improve the safety and performance of the lithium battery. Moreover, alumina also has very excellent thermal conductivity, can conduct heat well, and solves the problem of poor thermal conductivity of traditional materials, which is crucial for maintaining the temperature stability of the battery under high-load operation. In addition, the material containing alumina has good flame retardant properties. Even when reaching the combustion critical point at a high temperature, it can prevent large-scale combustion or explosion, further enhancing the safety of the battery. Of course, the thinning layer 300 can also be made of other materials with the same properties as alumina, which is not limited here.

[0041] The electrode layer 200 in this embodiment includes a first electrode layer 210 and a second electrode layer 220. The first electrode layer 210 covers the upper surface of the substrate layer 100, and the second electrode layer 220 covers the lower surface of the substrate layer 100. The length of the second electrode layer 220 is less than that of the first electrode layer 210. The first electrode layer 210 and the second electrode layer 220 are arranged in a staggered manner. The so-called staggered arrangement here means that the ends of the second electrode layer 220 and the first electrode layer 210 are not aligned. In this embodiment, the laying length of the second electrode layer 220 on the surface of the substrate layer 100 is less than that of the first electrode layer 210 on the surface of the substrate layer 100.

[0042] Of course, the first electrode layer 210 and the second electrode layer 220 can also be arranged opposite to each other, that is, the length of the first electrode layer 210 is the same as that of the second electrode layer 220, and both ends of the first electrode layer 210 are aligned with both ends of the second electrode layer 220.

[0043] The pole piece thinning technology is currently the key means to improve the edge bulge of the pole piece. However, conventional thinning is difficult to control, and the prior art often over-thins, that is, the thinning degree is significantly greater than the actual requirement, resulting in phenomena such as low capacity of the battery cell, distortion of the edge surface density, and lithium deposition at the edge of the pole piece. Eventually, it will also cause purple spots, lithium deposition, and cycling degradation at the edge of the pole piece. If the thinning size at the edge of the pole piece is too large, it will affect the surface density of the edge coating, resulting in a decrease in the coating amount of the pole piece, a low capacity of the battery cell, or a mismatch between the positive and negative capacities, and it is easy to form a lithium deposition area.

[0044] Please refer to Figure 1 and Figure 2, in this embodiment, the thinning layer 300 includes a first thinning layer 310 and a second thinning layer 320. The first thinning layer 310 is located at both ends of the first electrode layer 210, and the thickness of the first thinning layer 310 is less than that of the first electrode layer 210. The second thinning layer 320 is located at both ends of the second electrode layer 220, and the thickness of the second thinning layer 320 is less than that of the second electrode layer 220. For the first thinning layer 310 and the second thinning layer 320 located at the same end of the electrode layer 200, the distance between the end of the second thinning layer 320 far from the second electrode layer 220 and the end of the first thinning layer 310 far from the first electrode layer 210 along the extending direction of the substrate layer 100 is 0 to 0.6 mm, that is, the value range of L4 is 0 to 0.6 mm. L4 can be 0 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, etc. The distance L4 between the end of the second thinning layer 320 far from the second electrode layer 220 and the end of the first thinning layer 310 far from the first electrode layer 210 is determined according to the actual production situation and is not limited herein. By arranging the upper and lower two thinning layers 300 in a staggered manner and making the length of the second thinning layer 320 shorter than that of the first thinning layer 310, when the battery electrode sheet 1000 is subjected to subsequent processing, the flatness of the upper and lower surfaces of the battery electrode sheet 1000 can be ensured, and the performance of the battery electrode sheet 1000 can be guaranteed.

[0045] Of course, the ends of the first thinning layer 310 and the second thinning layer 320 can also be arranged in alignment, and their lengths are the same, which is not limited herein.

[0046] To prevent the excessive thinning size at the edge of the battery electrode sheet 1000 from affecting the surface density of the edge coating, resulting in a reduction in the coating amount of the battery electrode sheet 1000, and thus leading to a low cell capacity or a mismatch between the positive and negative electrode capacities, forming a lithium plating area, please continue to refer to Figure 1 and Figure 2 , in this embodiment, the length of the thinning layer 300 is 1 mm to 6 mm, that is, the value range of L2 is 1 to 6 mm. Specifically, the length of the thinning layer 300 can be 1 mm, 1.5 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, etc. The specific length of the thinning layer 300 is determined according to the actual situation and is not limited herein.

[0047] In this embodiment, the end of the electrode layer 200 is connected to the substrate layer 100 through a first rounded corner 230. Specifically, the radius of the first rounded corner 230 in this embodiment is 0.4 mm to 6 mm, that is, the value range of L3 is 0.4 to 6 mm. In detail, the radius L3 of the first rounded corner 230 can be 0.4 mm, 0.5 mm, 1 mm, 2 mm, 2.5 mm, 3 mm, 4 mm, 5 mm, 6 mm, etc., which is determined according to the actual production situation and is not limited herein.

[0048] Please refer to Figure 1 andFigure 2 , in order to prevent excessive thinning, the end of the thinning layer 300 away from the electrode layer 200 in this embodiment is connected to the substrate layer 100 through a second rounded corner 330. Specifically, the radius of the second rounded corner 330 in this embodiment is 1 mm to 5 mm, that is, the value range of L1 is 1 mm to 5 mm. The optimal value of the radius L1 of the second rounded corner 330 is 2.5 mm. Of course, L1 can also be other values, such as 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, etc., which is determined according to the actual production situation and is not limited here.

[0049] By providing the first rounded corner 230 and the second rounded corner 330, stress concentration at the ends of the thinning layer 300 and the electrode layer 200 can be reduced, and the strength and durability of the battery electrode sheet 1000 can be improved.

[0050] Please continue to refer to Figure 1 and Figure 2 , in order to ensure the activity of the battery electrode sheet 1000 and ensure the rate and efficiency of the electrochemical reaction, the thickness ratio of the thinning layer 300 to the thickness of the electrode layer 200 in this embodiment is less than or equal to two-thirds and greater than or equal to one-sixth. Please refer to Figure 2 , the thickness of the thinning layer 300 is H2, and the thickness of the electrode layer 200 is H1, that is, 1 / 6 ≤ (H2 / H1) ≤ 2 / 3. Specifically, H2 / H1 can be 1 / 6, 1 / 3, 2 / 3, etc., and the specific ratio is determined according to the actual production situation and is not limited here.

[0051] In summary, the battery electrode sheet 1000 includes a substrate layer 100, an electrode layer 200, and a thinning layer 300. The electrode layer 200 covers the surface of the substrate layer 100; the thinning layer 300 is located at both ends of the electrode layer 200, and the thickness of the thinning layer 300 is less than the thickness of the electrode layer 200. By providing the thinning layer 300 at both ends of the electrode layer 200 and the thickness of the thinning layer 300 is less than the thickness of the electrode layer 200, it can prevent the battery electrode sheet 1000 from bulging at the edge due to the edge thickness being higher than the thickness of the electrode layer 200 during rewinding, resulting in inability to rewind, thereby causing a decrease in the flatness of the battery electrode sheet 1000, and further affecting the performance of the battery electrode sheet 1000.

[0052] The above is only the 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 those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A battery pole piece, characterized in that: include: A base layer (100); An electrode layer (200), the electrode layer (200) covering the surface of the substrate layer (100); A skived layer (300), wherein the skived layer (300) is located at both ends of the electrode layer (200), and the thickness of the skived layer (300) is less than the thickness of the electrode layer (200).

2. The battery electrode according to claim 1, characterized in that: The electrode layer (200) comprises a first electrode layer (210) and a second electrode layer (220); the first electrode layer (210) covers the upper surface of the base layer (100), and the second electrode layer (220) covers the lower surface of the base layer (100); the length of the second electrode layer (220) is shorter than the length of the first electrode layer (210); and the first electrode layer (210) and the second electrode layer (220) are staggered.

3. The battery pole piece according to claim 2, characterized in that: The skived layer (300) comprises a first skived layer (310) and a second skived layer (320), wherein the first skived layer (310) is located at two ends of the first electrode layer (210), and the thickness of the first skived layer (310) is less than the thickness of the first electrode layer (210); the second skived layer (320) is located at two ends of the second electrode layer (220), and the thickness of the second skived layer (320) is less than the thickness of the second electrode layer (220); The first skived layer (310) and the second skived layer (320) are located at the same end of the electrode layer (200), and the distance between the end of the second skived layer (320) away from the second electrode layer (220) and the end of the first skived layer (310) away from the first electrode layer (210) along the extension direction of the base layer (100) is 0 to 0.6 mm.

4. The battery pole piece according to claim 1, characterized in that: The length of the skived layer (300) is 1 mm to 6 mm.

5. The battery pole piece according to claim 1, characterized in that: An end of the electrode layer (200) is connected to the base layer (100) via a first rounded corner (230).

6. The battery pole piece according to claim 5, characterized in that: The radius of the first rounded corner (230) is 0.4 mm to 6 mm.

7. The battery pole piece according to claim 1, characterized in that: The end of the skived layer (300) away from the electrode layer (200) is connected to the base layer (100) via a second rounded corner (330).

8. The battery pole piece according to claim 7, characterized in that: The radius of the second rounded corner (330) is 1 mm to 5 mm.

9. The battery pole piece according to claim 1, characterized in that: The ratio of the thickness of the skived layer (300) to the thickness of the electrode layer (200) is less than or equal to two thirds and greater than or equal to one sixth.

10. A battery cell, characterized in that: A battery pole piece (1000) comprising any one of claims 1 to 9.

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