Pole piece, battery, electric equipment and pole piece forming method

Abstract

The invention relates to the technical field of batteries, in particular to a pole piece, a battery, electric equipment and a pole piece forming method. The pole piece comprises a current collector and a dressing layer; the current collector comprises two surfaces opposite to each other along the thickness direction of the current collector; at least one surface is provided with a dressing layer; the dressing layer comprises a coating layer and a transition layer connected with the coating layer, the absolute value of the difference value between the thickness of the transition layer and the thickness of the coating layer is a, and the value range of a is (0 mu m, 160 mu m). According to the pole piece provided by the embodiment, the structure of the transition layer is introduced, so that the pore structure problem of the dressing layer can be effectively improved in the manufacturing process of the lithium ion battery.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a pole piece, a battery, an electrical device, and a pole piece forming method. Background Art

[0002] In the manufacturing process of lithium-ion batteries, pole pieces are key components, and their structure and material properties directly affect the performance and efficiency of the battery. Pole pieces are generally composed of a current collector and a dressing layer, where the current collector is responsible for conducting current, while the dressing layer is mainly used for the storage and release of lithium ions. However, an unavoidable problem during the processing of pole pieces is that after rolling, the pore structure of the dressing layer may shrink or form dead zones, which will hinder the migration of lithium ions and reduce their migration speed, thereby causing the battery to perform poorly at high power output. Summary of the Invention

[0003] The present application provides a pole piece, a battery, an electrical device and a pole piece forming method, which are used to solve the problem in the prior art of pole piece preparation that the pole piece is rolled, resulting in a reduction in the pore structure of the dressing layer or the appearance of dead areas, which leads to a decrease in battery performance.

[0004] A first aspect of the present application provides a pole piece, comprising:

[0005] a current collector comprising two surfaces facing each other along a thickness direction of the current collector;

[0006] At least one of the surfaces is provided with a dressing layer;

[0007] The dressing layer includes a coating layer and a transition layer connected to the coating layer. The absolute value of the difference between the thickness of the transition layer and the thickness of the coating layer is a, and the value range of a is (0 μm, 160 μm).

[0008] In one possible implementation, the current collector extends along a first direction, and a cross section of the transition layer perpendicular to the first direction has a parabolic edge at a side away from the current collector.

[0009] In one possible implementation, in the thickness direction of the current collector, the maximum distance from the surface of the transition layer away from the current collector to the current collector is not greater than the distance from the side of the coating layer away from the current collector to the current collector.

[0010] In one possible implementation, at least a portion of the surface of the transition layer facing away from the current collector is concave inward toward the current collector to form a recessed portion, and the depth of the recessed portion in the thickness direction of the current collector is no more than 160 μm.

[0011] In one possible implementation, in the thickness direction of the current collector, the minimum distance from the surface of the transition layer away from the current collector to the current collector is not less than the distance from the side of the coating layer away from the current collector to the current collector.

[0012] In one possible implementation, the transition layer is raised away from at least a portion of the surface of the current collector and away from the current collector to form a raised portion, and the height of the raised portion is no more than 4 μm in the thickness direction of the current collector.

[0013] In one possible implementation, the coating layer includes a first coating layer and a second coating layer arranged along the second direction, the transition layer is provided between the first coating layer and the second coating layer, and the size of the transition layer in the second direction is not greater than 3 mm.

[0014] In one possible implementation, the dressing layer includes multiple dressing layer groups, each of the dressing layer groups includes the first coating layer, the transition layer and the second coating layer distributed along the second direction, and multiple groups of the dressing layer groups are arranged in sequence along the second direction.

[0015] In one possible implementation, the transition layer has a different color from the first coating layer and / or the second coating layer.

[0016] In one possible implementation, the dressing layer includes a first coating layer and a second coating layer, the first coating layer and the second coating layer are arranged along the second direction, and the current collector extends along the first direction; the dressing layer is provided with a notch, and the notch is provided in the first coating layer and / or the second coating layer.

[0017] In one possible implementation, the pole piece further includes a pole tab, which is at least partially accommodated in the notch and connected to the current collector.

[0018] In one possible implementation, the current collector includes aluminum foil or copper foil.

[0019] A second aspect of the present application provides a battery, comprising:

[0020] case;

[0021] The pole piece as described in any one of the above items is arranged in the shell after being wound or stacked.

[0022] A third aspect of the present application provides an electrical device comprising a battery as described in any one of the above.

[0023] A fourth aspect of the present application provides a pole piece forming method, comprising the following steps:

[0024] Providing a current collector, wherein the current collector has two surfaces facing opposite directions of thickness;

[0025] A coating is performed on at least one surface of the current collector to form a coating layer having a coating layer and a transition layer, and the coating layer and the transition layer are connected; wherein the absolute value of the difference between the thickness of the transition layer and the thickness of the coating layer is a, and the value range of a is (0 μm, 160 μm].

[0026] In one possible implementation, the step of coating at least one surface of the current collector to form a coating layer having a coating layer and a transition layer includes the following steps:

[0027] providing a coating device, wherein the coating device moves relative to the current collector;

[0028] At least one coating is performed on the current collector to form a coating layer and a transition layer connected to each other on the current collector.

[0029] In a possible implementation, the coating device is provided with at least two coating ports, and the two coating ports are arranged sequentially along the second direction;

[0030] The current collector extends along a first direction, and the second direction is set at an angle to the first direction; the coating device moves relative to the current collector along the first direction; the coating device performs coating at at least two of the coating ports to form the connected coating layer and the transition layer.

[0031] In one possible implementation, the coating device includes a first gasket and a second gasket, the first gasket is provided with a first coating trough, and the second gasket is provided with a second coating trough; in the thickness direction of the current collector, the first gasket is on the orthographic projection of the second gasket, the first coating trough and the second coating trough are staggered, and the coating device outputs the coating layer from the first coating trough and outputs the transition layer from the second coating trough.

[0032] The implementation of the embodiments of the present application has the following beneficial effects:

[0033] In this embodiment of the pole piece, the introduction of a transition layer effectively improves the pore structure of the dressing layer during lithium-ion battery manufacturing. The transition layer maintains a relatively ideal porosity during rolling, reducing or avoiding pore shrinkage and the formation of dead zones. This arrangement can alleviate the problem of lithium ion migration obstruction during pole piece processing in the prior art, thereby ensuring the lithium ion migration rate within the pole piece and improving battery performance stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] To more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.

[0035] Figure 1 shows a three-dimensional view of a pole piece in an embodiment of the present invention;

[0036] Figure 2 shows a side view of a pole piece in an embodiment of the present invention;

[0037] Figure 3 shows an enlarged schematic diagram of a local structure of a pole piece in an embodiment of the present invention;

[0038] Figure 4 A schematic structural diagram of a pole piece in an embodiment of the present invention is shown;

[0039] Figure 5 A schematic structural diagram of a pole piece in another embodiment of the present invention is shown;

[0040] Figure 6 A flow chart of a pole piece forming method according to an embodiment of the present invention is shown;

[0041] Figure 7 It shows a schematic structural diagram of a first gasket and a second gasket in an embodiment of the present invention;

[0042] Reference numerals:

[0043] 10-pole piece;

[0044] 100-current collector;

[0045] 200 - dressing layer; 210 - coating layer; 211 - first coating layer; 212 - second coating layer; 220 - transition layer; 230 - notch;

[0046] 300-ear;

[0047] 20-first gasket; 21-first coating tank;

[0048] 30-second gasket; 31-second coating tank. DETAILED DESCRIPTION

[0049] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0050] In the manufacturing process of lithium-ion batteries, pole pieces are key components, and their structure and material properties directly affect the performance and efficiency of the battery. Pole pieces are generally composed of a current collector and a dressing layer, where the current collector is responsible for conducting current, while the dressing layer is mainly used for the storage and release of lithium ions. However, an unavoidable problem during the processing of pole pieces is that after rolling, the pore structure of the dressing layer may shrink or form dead zones, which will hinder the migration of lithium ions and reduce their migration speed, thereby causing the battery to perform poorly at high power output.

[0051] Based on this, see Figures 1 to 7 As shown, an embodiment of the present invention provides a pole piece 10, which includes a current collector 100 and a dressing layer 200, the current collector 100 includes two surfaces opposite to each other along its thickness direction; at least one surface is provided with a dressing layer 200; the dressing layer 200 includes a coating layer 210 and a transition layer 220 connected to the coating layer 210, the absolute value of the difference between the thickness of the transition layer 220 and the thickness of the coating layer 210 is a, and the value range of a is (0μm, 160μm].

[0052] In the electrode 10 of this embodiment, the introduction of a transition layer 220 effectively improves the pore structure of the dressing layer 200 during the lithium-ion battery manufacturing process. The provision of transition layer 220 enables the dressing layer 200 to maintain a relatively ideal porosity during the rolling process, reducing or avoiding pore shrinkage and the formation of dead zones. This configuration can alleviate the problem of lithium ion migration obstruction during the processing of the electrode 10 in the prior art, thereby ensuring the migration rate of lithium ions within the electrode 10 and improving the performance stability of the battery.

[0053] By limiting the difference a to within the range of (0 μm, 160 μm], the thickness difference between the transition layer 220 and the coating layer 210 can be effectively controlled, thereby optimizing the pore structure of the pole piece 10. Specifically, the value of a can be an intermediate value such as 0.1 μm, 80 μm or 160 μm to meet practical applications with different design requirements. In practical applications, determining a suitable thickness difference a is crucial to the performance of the pole piece. If the value of a is too large, it may lead to a reduction in the effectiveness of the transition layer 220, thereby affecting the transfer channel of lithium ions and causing a decrease in battery performance. Through reasonable control of the a value, the pole piece 10 can significantly improve the migration efficiency of lithium ions inside the battery, thereby reducing internal resistance and heat loss at high power output, thereby ensuring the performance stability of the battery.

[0054] It should be noted that, see Figure 1 and Figure 7 As shown, the Y direction in the figure is the first direction, the current collector 100 extends along the first direction, the X direction in the figure is the second direction, and the coating layer 210 and the transition layer 220 are arranged along the second direction; in this embodiment, the X direction and the Y direction can be set perpendicularly, and the pole piece 10 formed thereby is a rectangular structure. In other embodiments, the angle between the X direction and the Y direction can also be an acute angle, and the pole piece 10 formed thereby can be a parallelogram structure, which is not limited here.

[0055] In one embodiment, the cross section of the transition layer 220 perpendicular to the first direction is parabolic at the edge away from the current collector 100. This parabolic structural design can effectively optimize the migration path of lithium ions in the electrode 10, thereby improving the overall performance of the battery.

[0056] Because the transition layer 220 is parabolic on the side away from the current collector 100, it can create a larger surface area at the extended edge region. This design not only helps create a smoother lithium ion migration channel between the coating layer 210 and the transition layer 220, but also reduces the diffusion resistance of lithium ions in the transition layer 220. During high-rate charge and discharge, this structure effectively reduces the transmission time of lithium ions within the electrode, lowering internal resistance and improving the battery's instantaneous output capacity.

[0057] Furthermore, the parabolic design of the transition layer 220 helps alleviate stress concentration caused by the rolling process. When the pole piece 10 undergoes rolling, uneven pressure can cause structural damage or reduced pore size in some areas. The parabolic edge structure can achieve a certain degree of uniform stress distribution, reducing localized stress concentration.

[0058] Specifically, in one embodiment, in the thickness direction of the current collector 100, the maximum distance between the surface of the transition layer 220 on the side away from the current collector 100 and the current collector 100 is no greater than the distance between the side of the coating layer 210 away from the current collector 100 and the current collector 100. At least a portion of the surface of the transition layer 220 facing away from the current collector 100 is concave inward toward the current collector 100 to form a recessed portion, and the depth of the recessed portion in the thickness direction of the current collector 100 is no more than 160 μm.

[0059] In this embodiment, the transition layer 220 is concave toward the current collector 100, and the depth h of the transition layer 220 is no more than 160 μm. This design effectively improves the electrochemical reaction conditions inside the battery through the form of a concave structure. Specifically, the depth h of the transition layer 220 is limited to no more than 160 μm. Especially in the lithium cobalt oxide system, the setting of this depth helps to optimize the transmission efficiency of lithium ions between the electrode and the electrolyte. Compared with traditional designs, the control of the depth h can effectively reduce the internal impedance of the battery and improve the charge and discharge performance of the battery.

[0060] In addition, the concave design significantly increases the contact area between the electrolyte and the electrode 10, promotes the uniform distribution of lithium ions in the electrode material, and thus improves the overall energy density of the battery. Through this structure, the reaction activity and service life of the battery are enhanced, providing more ideal conditions for improving the power output and energy storage capacity of the battery. Specifically, the depth h of the transition layer 220 can be 160μm, 100μm, 74μm, 70μm, 50μm, 20μm, 10μm, depending on the dressing material and processing conditions used in the dressing layer 200, and is not limited here. It should be noted that, refer to Figure 2 The depth h of the transition layer 220 here refers to the straight-line distance between the vertex of the depression of the transition layer 220 and the plane where the surface of the coating layer 210 away from the current collector 100 is located.

[0061] In another embodiment, the minimum distance between the surface of the transition layer 220 facing away from the current collector 100 and the current collector 100 in the thickness direction of the current collector 100 is no less than the distance between the surface of the coating layer 210 facing away from the current collector 100 and the current collector 100. At least a portion of the surface of the transition layer 220 facing away from the current collector 100 is raised in a direction away from the current collector 100 to form a raised portion. The height of the raised portion in the thickness direction of the current collector 100 is no greater than 4 μm. In this case, the electrode sheet 10 can be a negative electrode sheet 10.

[0062] Specifically, the transition layer 220 in the transition region is convexly disposed in a direction away from the current collector 100 to form a convex portion, and the height of the convex portion in the direction perpendicular to the surface is no greater than 4 μm. In some embodiments, the convex portion is preferably no greater than 2 μm.

[0063] In a specific embodiment, the formation of the raised structure not only enhances contact between the electrode sheet 10 and the electrolyte, but also reduces stress caused by thermal expansion and contraction. Furthermore, the relatively small depth allows the overall thickness of the electrode sheet 10 to be controlled, thereby reducing the weight of the battery and increasing its energy density. By applying this solution, the electrode sheet 10 can effectively prevent an increase in interfacial impedance during charge and discharge, thereby improving the battery's cycle life and safety.

[0064] In one embodiment, the coating layer 210 includes a first coating layer 211 and a second coating layer 212 arranged along the second direction, and the transition layer 220 is arranged between the first coating layer 211 and the second coating layer 212. The size of the transition layer 220 in the second direction is not greater than 3 mm. Such a design can effectively improve the energy density of the battery.

[0065] The design of the transition layer 220 can also effectively reduce the stress concentration of the electrode 10 during heat treatment or charging and discharging, and reduce the possible material loss. In addition, the presence of the recessed structure increases the contact area between the electrolyte and the electrode material during the charging and discharging process of the battery, thereby increasing its reaction activity and improving the overall performance of the battery. By connecting the first coating layer 211 and the second coating layer 212 through a reasonably designed transition layer 220, while ensuring the mechanical strength of the dressing layer 200, it also provides greater flexibility for the subsequent battery packaging process and avoids the material waste caused by traditional manufacturing processes. Specifically, the size w of the transition layer 220 in the second direction can be 3mm, 2mm, 1mm, or 0.5mm, which is determined by the dressing material and processing conditions used in the dressing layer 200 and is not limited here. It should be noted that in order to improve the consistency of the dressing layer 200, the size of the transition layer 220 in the second direction is preferably as small as possible.

[0066] Specifically, the first coating layer 211 and the second coating layer 212 are at least partially dissolved in each other and solidified to form the transition layer 220 .

[0067] During the processing, the liquid dressing is first applied to the corresponding portions of the first coating layer 211 and the second coating layer 212 on the current collector 100. During the curing process of the first coating layer 211 and the second coating layer 212, the first coating layer 211 and the second coating layer 212 can dissolve and connect with each other under the mutual force of the liquid, so that after curing, a transition layer 220 is formed between the first coating layer 211 and the second coating layer 212. By providing the transition layer 220, the bonding force between the first coating layer 211 and the second coating layer 212 can be effectively enhanced, thereby improving the overall structural stability and performance of the dressing layer 200.

[0068] Specifically, the first coating layer 211 and the second coating layer 212 may be made of the same or different materials.

[0069] When these two layers are made of the same material, the overall molding consistency of the dressing layer 200 can be achieved, thereby achieving a higher yield rate in large-scale production. This consistency not only reduces adjustment costs during the production process, but also ensures that the electrical characteristics of each electrode are similar, further facilitating the stability of the electrode 10 under different usage conditions.

[0070] In addition, the transition layer 220 can be formed by the mutual dissolution of a first coating layer 211 and a second coating layer 212 of different materials. When different materials are selected, the migration rate of lithium ions can be significantly improved. A solvent system is used to ensure the compatibility of the first coating layer 211 and the second coating layer 212. Selecting a suitable solvent can not only optimize the formation efficiency of the transition layer 220, but also reduce the generation of bubbles during curing, thereby improving the uniformity and density of the finished product. Specifically, the coating layer 210 includes a plurality of first coating layers 211 and a plurality of second coating layers 212, and the plurality of first coating layers 211 and the plurality of second coating layers 212 are alternately arranged along the second direction.

[0071] During the manufacturing process, the design of the coating layer 210 facilitates the processing and preparation of the electrode 10. After coating, the electrode 10 can be cut directly between the first coating layer 211 of one set of coating layers 210 and the second coating layer 212 of another set of coating layers 210, thereby forming independent electrode 10. This design not only simplifies the production process, but also improves production efficiency and avoids unnecessary construction steps.

[0072] In practice, the alternating structure of coating layers 210 allows for flexible adjustment of the number of layers to suit different battery requirements. For example, the number of first coating layer 211 and second coating layer 212 can be one, two, or more, and can be optimized based on battery design requirements in practical applications. Using more coating layers allows for more complex structural designs, thereby meeting the multiple requirements of high-performance batteries for reactivity, conductivity, and mechanical properties.

[0073] In another embodiment, the dressing layer 200 includes multiple dressing layer groups, each dressing layer group includes a first coating layer 211 and a second coating layer 212 distributed along the second direction, and the multiple dressing layer groups are arranged sequentially along the second direction.

[0074] Specifically, in this embodiment, between two adjacent dressing layer groups, the first coating layer 211 of one dressing layer group is connected to the second coating layer 212 of the other dressing layer group, or the first coating layer 211 of one dressing layer group is connected to the first coating layer 211 of the other dressing layer group, that is, the two adjacent dressing layer groups are symmetrically arranged, which is not a sole limitation here.

[0075] With this arrangement, an effective interlayer connection can be formed between adjacent dressing layer groups, thereby enhancing the overall strength and stability of the electrode 10, thereby improving its reliability in subsequent processing.

[0076] In one embodiment, the notches 230 of two adjacent dressing layer groups are connected or spaced apart.

[0077] When two adjacent notches 230 are spaced apart, during subsequent cutting, cutting can be performed between the first coating layer 211 of one dressing layer group and the second coating layer 212 of the adjacent dressing layer group to form a complete electrode 10 having both the first coating layer 211 and the second coating layer 212. This allows for more efficient use of raw materials, reduces waste throughout the production process, and improves manufacturing efficiency. In addition, because the dressing layer group forms the transition layer 220, the electrode 10 can form the tab 300 directly on the current collector 100. This process greatly simplifies the production process, avoids steps such as laser cleaning or adhesive stripping that are required in traditional processes, and reduces production costs.

[0078] Specifically, in a scheme where the first coating layer 211 of one dressing layer group is connected to the second coating layer 212 of another dressing layer group, the two notches 230 may be separated by the first coating layer 211 of one group, or may be staggered in the first direction, without being limited here. In an embodiment where two adjacent dressing layer groups are symmetrically arranged, the two notches 230 may be staggered in the first direction.

[0079] Of course, when the two slots 230 are connected, in one embodiment, the sizes of the two slots 230 in the first direction can be equal and the edges can be aligned; in another embodiment, the two slots 230 can be staggered in the first direction but still partially connected, and the sizes of the two slots 230 in the first direction can also be different, which is not a sole limitation here.

[0080] In terms of specific implementation, the formation of the transition layer 220 can be achieved by finely controlling the materials of different coating layers, such as using a co-extrusion process or a hot pressing fusion process, which not only ensures a firm bond between the first coating layer 211 and the second coating layer 212, but also effectively improves the electrical performance and mechanical strength of the electrode 10. Considering the polarization problem at the joint of the electrode 10, Figure 4The dressing layer group of the U-shaped parallel-connected electrode 10 shown can use a main material that slows down polarization to a certain extent to ensure the isotropy of lithium ion migration in the electrode 10.

[0081] With this arrangement, during the preparation of the electrode 10 , longitudinal coating can be performed on the current collector 100 at one time to form multiple groups of dressing layers arranged side by side. After the coating process is cured, a electrode 10 having multiple groups of dressing layers can be formed on the electrode 10 .

[0082] Furthermore, the transition layer 220 has a different color from the first coating layer 211 and / or the second coating layer 212 .

[0083] This design takes into account that, during actual production, even if the first coating layer 211 and the second coating layer 212 utilize identical slurry compositions, color differences in the transition layer 220 may still occur. This phenomenon is due to a variety of factors, including but not limited to differences in additive content, varying gasket opening widths, variations in the distance between the front and rear cavities of the die, and varying degrees of shear applied to the coating slurry. These factors combine to result in significantly different colors in the transition layer during the coating process, even when using the same primary slurry, resulting in color differences, while the non-transition layer portion maintains a consistent color.

[0084] Further analysis shows that the dividing line or dividing portion formed by the color difference of the spliced ​​transition layer 220 extends through the thickness direction of the pole piece 10 and / or extends along the width direction of the pole piece 10. The existence of this dividing line or portion is not affected by the protrusions or depressions of the transition layer 220, which means that its shape and position are relatively stable. Such a design can effectively guide users to identify the boundaries of different coatings, especially in battery designs that need to clearly identify different performance areas. The existence of the dividing line can serve as an important visual guide. If the slurry composition of the first coating layer 211 and the second coating layer 212 is inconsistent, it is more likely to cause a color difference between the transition layer 220 and the first coating layer 211 and / or the second coating layer 212.

[0085] In one embodiment, the second coating layer 212 defines at least one notch 230 .

[0086] Specifically, the number of the notches 230 can be one, two, or more than two, which is not limited here. The design of providing multiple notches 230 not only enhances the flexibility of the material but also optimizes the structure to adapt to different application requirements.

[0087] The slot 230 can serve as a convenient channel for connecting the tab 300, making the installation of the tab 300 easier and reducing the need for subsequent assembly steps. In particular, this design can effectively improve production efficiency and reduce labor costs during mass production.

[0088] Furthermore, the notches 230 are provided on the second coating layer 212 , and a plurality of notches 230 are spaced apart along the first direction.

[0089] In this embodiment, the coating process of the dressing layer 200 is highly flexible. During the application of the second coating layer 212, an intermittent coating method can be employed, so that after the second coating layer 212 is formed, the notches 230 are naturally formed through appropriate coating techniques. This process not only effectively reduces dependence on subsequent processing steps but also ensures material utilization.

[0090] Similarly, during the coating process of the first coating layer 211, a similar interval coating method can be adopted so that the first coating layer 211 also forms a notch 230 after being formed. In this way, the structure between the first coating layer 211 and the second coating layer 212 can be flexibly designed to meet specific performance requirements. It is worth noting that the first coating layer 211 and the second coating layer 212 can be spaced apart and coated at the same time. The two notches 230 formed at this time can be connected or spaced apart. This flexibility enables the pole piece 10 to better adapt to diverse design requirements in application.

[0091] The advantages of this coating method are that it can improve processing efficiency and reduce material waste during the production process. Since the design of the notch 230 is realized during the coating stage, the need for subsequent complex processes is reduced, and material loss caused by cleaning or peeling is also reduced.

[0092] It should be noted that the notch 230 may be located only on the first coating layer 211 or the second coating layer 212 , or on both the first coating layer 211 and the second coating layer 212 , depending on the design requirements of the electrode 10 and is not limited here.

[0093] This layout allows the first coating layer 211 and the second coating layer 212 to function effectively within their respective functional areas, while also achieving reasonable material utilization. In particular, when at least one of the first coating layer 211 and the second coating layer 212 is provided with a notch 230 extending along the first direction, this design allows the tab 300 to be directly accommodated and connected within the notch, thereby simplifying the electrode manufacturing process. The notch 230 can be formed during the coating process through an intermittent coating process, effectively controlling the relationship between notch formation and material loss.

[0094] It should be pointed out that the arrangement of the first coating layer 211 and the second coating layer 212 also allows for diversified optimization. For example, in a specific design, it is possible to consider adding a third coating layer or more coating layers, which will further enhance the overall performance and adaptability of the electrode.

[0095] In one embodiment, the pole piece 10 further includes a pole tab 300 . The pole tab 300 is at least partially accommodated in the notch 230 and connected to the current collector 100 .

[0096] In this embodiment, the notches 230 formed during the processing of the dressing layer 200 provide dedicated space for the installation of the tabs 300. Specifically, the design of the notches 230 ensures that the tabs 300 can be effectively embedded therein and achieve a good electrical connection with the current collector 100. This design not only improves the stability of the tabs 300 but also effectively reduces the risk of poor contact caused by welding or other connection methods.

[0097] During the installation process of the tab 300, it is first placed in the notch 230, and then the tab 300 is connected to the current collector 100. The entire process is simple and efficient. Due to the reasonable location and design of the notch 230, the tab 300 and the current collector 100 are seamlessly connected, greatly simplifying the manufacturing process of the pole piece 10.

[0098] Specifically, the current collector 100 includes aluminum foil or copper foil.

[0099] In this embodiment, aluminum foil and copper foil are selected as the current collector 100, corresponding to different types of pole pieces 10 applications. Specifically, aluminum foil is usually used in the preparation of positive pole pieces. Due to its excellent electrical conductivity and suitable chemical stability, it plays a key role in applications such as lithium-ion batteries. In addition, the light weight of aluminum is also conducive to reducing the overall mass of the battery and improving energy density. Copper foil is mostly used for negative pole pieces. Due to its good electrical conductivity and corrosion resistance, it ensures the performance stability of the negative electrode under high current working conditions. In the design and preparation process, it is also crucial to select suitable materials. For example, for the aluminum foil of the positive pole piece, its thickness and surface treatment process can be controlled to optimize the electrical conductivity and electrochemical performance. At the same time, the copper foil of the negative pole piece can also improve its surface roughness through electroplating technology to increase the adhesion of the active material, thereby improving the charge and discharge efficiency and cycle stability of the battery.

[0100] The present invention further provides a battery comprising a housing and the pole piece 10 according to any one of the above embodiments. The pole piece 10 is wound or stacked and then placed in the housing.

[0101] It is understood that in the battery of this embodiment, by providing the electrode 10 of any of the above embodiments, the electrode 10 of this embodiment introduces the structure of the transition layer 220, which effectively improves the pore structure problem of the dressing layer 200 during the manufacturing process of the lithium-ion battery. Due to the provision of the transition layer 220, the dressing layer 200 can maintain a relatively ideal porosity during the rolling process, reducing or avoiding pore shrinkage and the formation of dead zones. This provision can improve the problem of lithium ion migration obstruction during the processing of the electrode 10 in the prior art, thereby ensuring the migration rate of lithium ions in the electrode 10, and thus improving the performance stability of the battery.

[0102] The present invention further provides an electrical device, which includes the electrode 10 in any one of the above embodiments, or the battery in any one of the above embodiments.

[0103] In the electrical equipment of this embodiment, by providing a pole piece 10 in any of the above embodiments, or providing a battery provided with a pole piece 10 in any of the above embodiments, the electrical equipment can better support high-efficiency electrical energy storage and conversion, and meet the growing demand for electricity, especially in the fields of mobile devices, electric vehicles and renewable energy storage systems.

[0104] See Figure 6 As shown, the present invention further provides a pole piece forming method, which can be applied to the pole piece 10 in any of the above embodiments. Specifically, the pole piece forming method includes the following steps:

[0105] Step S100 : providing a current collector 100 , wherein the current collector 100 has two surfaces facing opposite directions in thickness direction.

[0106] Step S200, coating is performed on at least one surface of the current collector 100 to form a dressing layer 200 having a coating layer 210 and a transition layer 220, and the coating layer 210 and the transition layer 220 are connected; wherein the absolute value of the difference between the thickness of the transition layer 220 and the thickness of the coating layer 210 is a, and the value range of a is (0μm, 160μm]; in this step, a mixed dressing is first prepared according to a predetermined ratio. The positive electrode dressing can adopt a composition of active material: conductive agent: binder = 100:1.1:0.8, and the negative electrode dressing can adopt a composition of active material: conductive agent: thickener: binder = 100:0.3:1:1.1. In some embodiments, the ratio of active material: conductive agent: thickener: binder in the dressing can also be 100:0–3:0.5–3:0.5–15, which is determined according to the design requirements of the dressing and is not limited here.

[0107] In this embodiment of the pole piece forming method, the introduction of a forming transition layer 220 effectively improves the pore structure of the dressing layer 200 during the lithium-ion battery manufacturing process. The provision of the transition layer 220 enables the dressing layer 200 to maintain a relatively ideal porosity during the rolling process, reducing or avoiding pore shrinkage and the formation of dead zones. This arrangement can alleviate the problem of lithium ion migration obstruction during the processing of the pole piece 10 in the prior art, thereby ensuring the migration rate of lithium ions within the pole piece 10 and improving the performance stability of the battery.

[0108] Furthermore, step S200 further includes the following steps:

[0109] A coating device is provided, and the coating device is moved relative to the current collector 100. Specifically, the coating device can be moved relative to the fixed current collector 100, the current collector 100 can be moved relative to the fixed coating device, or both can move simultaneously and relative to each other. In this step, the coating is performed by moving the coating device along a first direction on the current collector 100;

[0110] At least one coating process is performed on the current collector 100 to form a coating layer 210 and a transition layer 220 connected to each other on the current collector 100 .

[0111] In this step, by adopting a dual linear motor gap valve body and a dual feed cavity structure for coating, the dressing coating and blank length in the feed cavity can be precisely adjusted by the PLC-controlled motor. This allows precise transverse splicing to be achieved on the current collector 100 for special-shaped coating, and ultimately forms a coating layer 210 and a transition layer 220, respectively. Finally, the coated electrode 10 is dried and cured, and the drying and curing conditions should be controlled within the optimal curing parameter range of the dressing to ensure the performance of the final electrode 10. After curing is completed, the dried and cured electrode 10 can be quality inspected, including coating accuracy, thickness uniformity, etc., to ensure that each electrode 10 meets the design requirements. After passing the test, precise roller pressing and slitting are performed according to the size requirements of the battery core.

[0112] It should be noted that in other embodiments, the PLC can also be replaced by STM32 (STM32 microcontroller, a 32-bit microcontroller with an ARM Cortex-M core), a single-chip microcomputer, an FPGA (field programmable gate array, full name Field Programmable Gate Array), an ARM (ARM processor, full name Advanced RISC Machine), etc., to directly control the coating equipment.

[0113] Specifically, the coating equipment in this embodiment can utilize a dual linear motor gap valve body, a dual die head feed cavity, a single-layer die head or a dual-layer die head, and a corresponding gasket striping and partitioning design to meet the requirements of the special-shaped coating process. When using a dual-layer die head for processing, the coating layer 210 and the transition layer 220 can be coated simultaneously in one go, achieving high processing efficiency.

[0114] In one embodiment, the coating device is provided with at least two coating ports, and the two coating ports are arranged in sequence along the second direction; the current collector 100 extends along the first direction, and the second direction is arranged at an angle to the first direction; the coating device moves relative to the current collector 100 along the first direction for coating; the coating device performs coating at at least two coating ports to form a connected coating layer 210 and a transition layer 220.

[0115] In this embodiment, the current collector 100 can be partitioned along the second direction according to design requirements, and a corresponding feed cavity and nozzle partition are allocated in each partition to achieve subsequent multi-strip flow channel coating.

[0116] See Figure 7 As shown, in one embodiment, the coating device includes a first gasket 20 and a second gasket 30, the first gasket 20 is provided with a first coating trough 21, and the second gasket 30 is provided with a second coating trough 31; the first coating trough 21 and the second coating trough 31 are alternately arranged on the orthographic projection of the first gasket 20 on the second gasket 30, and the coating device outputs a coating layer 210 from the first coating trough 21 and a transition layer 220 from the second coating trough 31.

[0117] In this embodiment, the first coating slots 21 and the second coating slots 31 can be staggered. When the coating equipment uses the first gasket 20 and the second gasket 30 of this embodiment for coating, the coating layer 210 and the transition layer 220 arranged in sequence along the first direction can be simultaneously formed in a single coating operation. By changing the shape and size of the first gasket 20 and the second gasket 30, special coating requirements for different areas can be met.

[0118] Specifically, this pole piece forming method can adopt at least two processes: First, as described in any of the above embodiments, a double-layer die head with a staggered double-layer gasket is used to perform regional coating to complete pole piece splicing; second, a single-layer double-cavity die head with an integrated partitioned gasket is used to perform regional coating to complete pole piece splicing; by using a PLC to control the feed gap valve body and screw pump of the two regions, and by controlling the amount of coating and the size of the blank space of the coating at the feed port of the two regions, the prototype of the special-shaped coated pole piece is achieved. In addition, by adjusting the transition layer 220 and the head and tail of the two regional strips in detail, the final one-time formed special-shaped battery pole piece is obtained.

[0119] When adopting the pole piece 10 forming scheme of this embodiment, the coating equipment can form the first coating layer 211 and the second coating layer 212 respectively in one coating process. At this time, the first coating layer 211 and the second coating layer 212 dissolve each other to form a transition layer 220, and at least one coating layer 210 can be coated at intervals to form a notch 230 to correspond to the reserved slot. In the subsequent processing process, there is no need to clean or peel off the dressing layer 200. By optimizing the processing steps, not only the processing efficiency can be improved, but also the waste of materials can be avoided.

[0120] Specifically, the current collector 100 is provided with the tab 300 mounted in the notch 230 .

[0121] In this embodiment, by performing intermittent coating on the second coating layer 212 to form a transition layer 220, the pole ear 300 can be installed in the slot 230 of the current collector 100. Compared with the traditional pole piece processing method, subsequent processing does not require laser cleaning and glue peeling, and the pole ear 300 is directly formed by methods such as cutting, thereby improving processing efficiency and avoiding waste of dressing raw materials.

[0122] See Figure 3 As shown, it should be noted that the dressing slurry itself has leveling properties and surface tension, so the slurry gap at the transition layer 220 where the first coating layer 211 and the second coating layer 212 are spliced ​​is approximately parabolic in shape. Preferably, the width of the transition layer 220 in the Y direction is ≤ 3 mm. Based on this, the area S of the cross-section of the transition layer 220 is calculated as follows:

[0123] First, determine the parabola expression as y=ax 2 +bx+c, reference Figure 2 In the placement state shown, the three slope mutation points are set to (-1.5, β1), (1.5, β2), and (0, α).

[0124] When β1=β2=β (β is the wet film coating thickness), we can get:

[0125]

[0126] Wherein, α is the vertical coordinate of the lowest point of the transition layer 220 , β1 is the vertical coordinate of the left end point of the transition layer 220 , and β2 is the vertical coordinate of the right end point of the transition layer 220 .

[0127]

[0128] Taking the positive electrode of the fast charging system as an example, a slurry with a surface density of ρ and a solid content of η is used for coating. Among them, the range of ρ for the lithium cobalt oxide system is [10mg / cm 2 ,15mg / cm 2], η range is [75%, 80%], then β range is [46μm, 74μm], and α range is [0, β]. For system considerations and referring to the on-site thickness tolerance requirements, the negative electrode dressing joint can be controlled to have a residual material state or a state consistent with the surrounding area. The residual material thickness is ≤ 2μm compared to the average thickness.

[0129] In the description of the embodiments of the present application, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the embodiments of the present application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0130] In the description of the embodiments of this application, it should be noted that, unless otherwise specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of this application based on the specific circumstances.

[0131] In the embodiments of the present application, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, a first feature being "above," "above," and "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0132] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiments of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

[0133] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A pole piece (10), characterized in that: include: A current collector (100), comprising two surfaces facing each other along a thickness direction of the current collector (100); At least one of the surfaces is provided with a dressing layer (200); The dressing layer (200) comprises a coating layer (210) and a transition layer (220) connected to the coating layer (210), the absolute value of the difference between the thickness of the transition layer (220) and the thickness of the coating layer (210) is a, and the value range of a is (0 μm, 160 μm].

2. The pole piece (10) according to claim 1, characterized in that The current collector (100) extends along a first direction, and a cross section of the transition layer (220) perpendicular to the first direction has a parabolic edge at a side away from the current collector (100).

3. The pole piece (10) according to claim 2, characterized in that: In the thickness direction of the current collector (100), the maximum distance from the surface of the side of the transition layer (220) away from the current collector (100) to the current collector (100) is not greater than the distance from the side of the coating layer (210) away from the current collector (100) to the current collector (100).

4. The pole piece (10) according to claim 3, characterized in that At least a portion of the surface of the transition layer (220) facing away from the current collector (100) is concave inward toward the current collector (100) to form a recessed portion, and the depth of the recessed portion in the thickness direction of the current collector (100) is no more than 160 μm.

5. The pole piece (10) according to claim 2, characterized in that: In the thickness direction of the current collector (100), the minimum distance from the surface of the side of the transition layer (220) away from the current collector (100) to the current collector (100) is not less than the distance from the side of the coating layer (210) away from the current collector (100) to the current collector (100).

6. The pole piece (10) according to claim 5, characterized in that At least a portion of the surface of the transition layer (220) is away from the current collector (100) and is raised in a direction away from the current collector (100) to form a raised portion, and the height of the raised portion in the thickness direction of the current collector (100) is not greater than 4 μm.

7. The pole piece (10) according to claim 1, characterized in that The coating layer (210) comprises a first coating layer (211) and a second coating layer (212) arranged along a second direction, the transition layer (220) is arranged between the first coating layer (211) and the second coating layer (212), and the size of the transition layer (220) in the second direction is not greater than 3 mm.

8. The pole piece (10) according to claim 7, characterized in that The coating layer (210) includes a plurality of the first coating layers (211) and a plurality of the second coating layers (212), and the plurality of the first coating layers (211) and the plurality of the second coating layers (212) are alternately arranged along the second direction.

9. The pole piece (10) according to claim 7, characterized in that The dressing layer (200) includes a plurality of dressing layer groups, each of the dressing layer groups includes the first coating layer (211), the transition layer (220) and the second coating layer (212) distributed along the second direction, and the plurality of dressing layer groups are arranged in sequence along the second direction.

10. The pole piece (10) according to claim 7, characterized in that The transition layer (220) has a different color from the first coating layer (211) and / or the second coating layer (212).

11. The pole piece (10) according to any one of claims 1 to 10, characterized in that: The dressing layer (200) comprises a first coating layer (211) and a second coating layer (212), wherein the first coating layer (211) and the second coating layer (212) are arranged along a second direction, and the current collector (100) extends along the first direction; the dressing layer (200) is provided with a notch (230), and the notch (230) is provided in the first coating layer (211) and / or the second coating layer (212).

12. The pole piece (10) according to claim 11, characterized in that The second coating layer (212) is provided with at least one notch (230).

13. The pole piece (10) according to claim 12, characterized in that There are a plurality of the notches (230), and the notches (230) are provided on the second coating layer (212). The plurality of the notches (230) are spaced apart along the first direction.

14. The pole piece (10) according to claim 11, characterized in that The pole piece (10) further includes a pole tab (300), wherein the pole tab (300) is at least partially accommodated inside the notch (230) and connected to the current collector (100).

15. The pole piece (10) according to any one of claims 1 to 10, characterized in that: The current collector (100) comprises aluminum foil or copper foil.

16. A battery, characterized in that: include: case; The pole piece (10) according to any one of claims 1 to 15, wherein the pole piece (10) is arranged in the shell after being wound or stacked.

17. An electrical device, characterized in that: Comprising the battery of claim 16.

18. A pole piece forming method, characterized in that: The steps include: Providing a current collector (100), wherein the current collector (100) has two surfaces facing opposite directions in thickness; A coating is performed on at least one surface of the current collector (100) to form a coating layer (200) having a coating layer (210) and a transition layer (220), and the coating layer (210) and the transition layer (220) are connected; wherein the absolute value of the difference between the thickness of the transition layer (220) and the thickness of the coating layer (210) is a, and the value range of a is (0 μm, 160 μm].

19. The pole piece forming method according to claim 18, characterized in that: The step of coating at least one surface of the current collector (100) to form a dressing layer (200) having a coating layer (210) and a transition layer (220) comprises the following steps: providing a coating device, wherein the coating device moves relative to the current collector (100); At least one coating is performed on the current collector (100) to form a coating layer (210) and a transition layer (220) connected to each other on the current collector (100).

20. The pole piece forming method according to claim 19, characterized in that: The coating device is provided with at least two coating ports, and the two coating ports are arranged sequentially along the second direction; The current collector (100) extends along a first direction, and the second direction is arranged at an angle to the first direction; the coating device moves relative to the current collector (100) along the first direction; the coating device performs coating at at least two of the coating ports to form the connected coating layer (210) and the transition layer (220).

21. The pole piece forming method according to claim 20, characterized in that: The coating device comprises a first gasket (20) and a second gasket (30), wherein the first gasket (20) is provided with a first coating trough (21), and the second gasket (30) is provided with a second coating trough (31); in the thickness direction of the current collector (100), the first gasket (20) is on the orthographic projection of the second gasket (30), the first coating trough (21) and the second coating trough (31) are arranged alternately, and the coating device outputs the coating layer (210) from the first coating trough (21) and outputs the transition layer (220) from the second coating trough (31).

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