Anti-precipitation lithium cathode plate and anti-precipitation lithium battery

Abstract

The utility model provides an anti-precipitation lithium cathode plate and an anti-precipitation lithium battery, which are used for manufacturing a winding battery cell, and comprise a current collector, at least one coating surface is arranged on the current collector, and the coating surface comprises an end part area and a winding area; the end area is located at the winding starting end of the coating face in the first direction, and / or the end area is located at the winding ending end of the coating face in the first direction; the first direction is the winding direction of the current collector, the current collector comprises a body and a bulge, the bulge is arranged in the end part area, the bulge protrudes towards a second direction relative to the body, and the second direction is the orientation of the coating surface; and a cathode active material layer, wherein the cathode active material layer is arranged on the coating surface. According to the lithium precipitation prevention cathode piece, lithium precipitation at the head end and the tail end of the pole piece can be effectively avoided.

Description

Technical Field

[0001] This utility model relates to the field of new energy technology, and in particular to an anti-lithium plating cathode sheet and an anti-lithium plating battery. Background Technology

[0002] With continuous technological advancements and innovation, the demand for various smart devices, especially smartphones and computers, is growing daily. The widespread adoption of these devices has led to higher requirements for the performance and safety of smart products. Among numerous performance indicators, energy density and safety have become the primary focus for both consumers and manufacturers. To meet these demands, higher coating weights and compaction are employed, posing increasing challenges to the charging capacity of the system and making batteries more prone to lithium plating. Particularly in wound cells, due to variations in coating precision, the cathode coating head tends to have more active material, while the anode coating tail, with its thinned areas, tends to have less active material. Both result in lower local CB values ​​at the anode head and tail, leading to poor lithium intercalation. Furthermore, the need for tape at the head and / or tail of the electrode for finishing and short-circuit protection causes lithium ions to accumulate and plating at the tape edges. Therefore, a new battery design is needed to prevent lithium plating at the electrode head and tail. Utility Model Content

[0003] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes an anti-lithium-plating cathode sheet, which can effectively prevent lithium plating from occurring at the ends of the electrode sheet.

[0004] This utility model also proposes an anti-lithium plating battery.

[0005] According to a first aspect of the present invention, an anti-lithium plating cathode sheet is used to manufacture a wound battery cell, comprising: a current collector having at least one coating surface, the coating surface including an end region and a winding region; the end region being located at the winding start end of the coating surface along a first direction, and / or the end region being located at the winding end end of the coating surface along the first direction; the first direction being the winding direction of the current collector, the current collector including a body and a protrusion, the protrusion being disposed in the end region, the protrusion protruding relative to the body in a second direction, the second direction being the orientation of the coating surface; and a cathode active material layer disposed on the coating surface and covering the protrusion.

[0006] The lithium-plating-resistant cathode sheet according to the first aspect of the present invention has at least the following beneficial effects: by providing protrusions at the starting position and the ending position of the current collector, the mass of the cathode active material at the end region of the current collector is reduced, thereby effectively preventing lithium plating at the starting and ending ends of the winding of the lithium-plating-resistant cathode sheet.

[0007] According to some embodiments of the present invention, the current collector includes a first layer and a second layer, the second layer covering the first layer to form the coating surface, and the first layer is provided with protrusions to form protrusions on the coating surface.

[0008] According to some embodiments of the present invention, it also includes a tab connected to the current collector, and the tab in the end region is disposed on the protrusion.

[0009] According to some embodiments of the present invention, the width of the end region in the first direction is not less than 3 mm.

[0010] According to some embodiments of the present invention, the protrusion array is disposed in the end region, and the height of the protrusion in the second direction is not less than 1 μm and not more than 200 μm.

[0011] According to some embodiments of the present invention, the interval between the protrusions in the first direction is not less than 0.5 mm, the interval between the protrusions in the third direction is not less than 0.5 mm, and the third direction is the width direction of the current collector.

[0012] According to some embodiments of the present invention, the height of the protrusion in the second direction does not exceed the height of the cathode active material layer in the second direction.

[0013] According to some embodiments of the present invention, the width of the protrusion in the first direction is not less than 0.1 mm, and the width of the protrusion in the third direction is not less than 0.1 mm.

[0014] According to some embodiments of this utility model, in the third direction, the distance between the end region and the edges on both sides of the current collector is not less than 1 mm and not more than 5 mm, where the third direction is the width direction of the current collector; when the end region is located at the starting end of the winding of the coating surface, the distance between the end region and the starting end edge of the current collector is not less than 3 mm; when the end region is located at the ending end of the winding of the coating surface, the distance between the end region and the ending end edge of the current collector is not less than 3 mm.

[0015] The lithium-plating-resistant battery according to a second aspect of the present invention includes the lithium-plating-resistant cathode sheet described in any of the above embodiments.

[0016] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the current collector area of ​​a lithium plating-resistant cathode sheet according to the present invention;

[0018] Figure 2 This is a schematic diagram of the current collector structure of an anti-lithium plating cathode sheet according to the present invention;

[0019] Figure 3 This is a partial structural diagram of the end region of an anti-lithium plating cathode sheet according to the present invention;

[0020] Figure 4 This is a cross-sectional structural diagram of a lithium plating-resistant cathode sheet according to the present invention;

[0021] Figure 5 This is a schematic diagram of the internal structure of the current collector of a lithium plating-resistant cathode sheet according to the present invention.

[0022] Icon labels:

[0023] 1. Current collector; 11. End region; 12. Winding region; 13. Body; 14. Protrusion; 15. Insulating layer; 16. Conductive layer; 2. Cathode active material layer; 3. Tab. Detailed Implementation

[0024] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0025] In the description of this utility model, it should be understood that the orientation descriptions, such as up and down, are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0026] In the description of this utility model, "multiple" refers to two or more. The use of "first" and "second" is for distinguishing technical features only and should not be construed as indicating or implying relative importance, or implicitly indicating the number of technical features or their sequential relationship.

[0027] In the description of this utility model, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this utility model in conjunction with the specific content of the technical solution.

[0028] The battery manufacturing process is a series of precise and complex steps, involving everything from selecting high-quality raw materials to the meticulous assembly of the final product. First, the manufacturing team carefully selects suitable positive electrode materials, such as compounds like lithium cobalt oxide, lithium manganese oxide, or lithium iron phosphate, because they offer stable chemical reactions and long lifespans. Simultaneously, the selection of negative electrode materials is equally important; common choices include graphite or silicon-based materials, which need to possess good conductivity and sufficient capacity to store energy. In preparing the electrolyte, engineers dissolve lithium salts in specific organic solvents to ensure the electrolyte has good conductivity and chemical stability. These electrolytes are the medium for the chemical reactions inside the battery and have a direct impact on the battery's performance and lifespan. Next, the positive electrode materials, negative electrode materials, and separator are assembled according to a carefully designed structure. In this stage, the positive electrode material is uniformly coated on aluminum foil to form the positive current collector, while the negative electrode material is coated on copper foil to form the negative current collector. The separator plays a crucial role in isolating the positive and negative electrodes while allowing ions to pass through. These components are combined together by winding or stacking to form the battery cell. The shape of a battery cell can be traditionally cylindrical, commonly square, or more flexible pouch form, depending on the application and design requirements. After assembly, the cells undergo a rigorous testing and aging process. This process involves a series of charge-discharge cycles to stabilize the battery's chemical properties, ensuring consistent and reliable power output in actual use. The aging process is an indispensable part of battery manufacturing, helping to eliminate performance fluctuations that may occur during initial use. After testing and aging, qualified cells are further assembled into battery packs. At this stage, the integration of the Battery Management System (BMS) becomes crucial, as it monitors and manages the charging and discharging process, ensuring the battery's safety and efficiency under various usage conditions. Battery pack assembly requires precise processes and strict quality control to ensure that each battery cell works collaboratively to achieve optimal performance.

[0029] In the manufacturing of wound batteries, positive electrode sheets, separators, and negative electrode sheets need to be stacked, and then wound to form a wound battery. During winding, to prevent short circuits between the positive and negative electrode sheets, adhesive tape is placed at the beginning and / or end of the winding process. Furthermore, placing adhesive tape at the beginning and / or end of the winding process also increases the margin for the anode sheet to wrap around the cathode sheet.

[0030] Reference Figure 1 , Figure 2 , Figure 4 and Figure 5 The lithium plating-resistant cathode sheet in the first embodiment of this utility model is used to manufacture a wound battery cell, comprising: a current collector 1 and a cathode active material layer 2. The current collector 1 includes at least one coating surface, and the coating surface includes an end region 11 and a winding region 12. The current collector 1 can have one coating surface or two oppositely arranged coating surfaces. When the current collector 1 has two coating surfaces, cathode active material can be disposed on both coating surfaces. A protrusion 14 can be disposed on one of the coating surfaces or on both coating surfaces. The end region 11 is located at the winding start end of the coating surface along a first direction, and / or at the winding end end of the coating surface along the first direction; the first direction is the winding direction of the current collector 1. The current collector 1 includes a body 13 and a protrusion 14, the protrusion 14 is disposed on the end region 11, and the protrusion 14 protrudes relative to the body 13 in a second direction, which is the orientation of the coating surface; the cathode active material layer 2 is disposed on the coating surface. Because tape is needed at the beginning and end of the winding of current collector 1 to isolate the positive and negative electrodes, the presence of the tape can cause lithium ions to aggregate, leading to lithium plating at the beginning and end of the winding of current collector 1. Specifically, lithium plating occurs in the end region 11. Furthermore, due to differences in the coating precision of the active material, either too much active material is coated in the end region 11 of the positive electrode or too little in the end region 11 of the negative electrode. Both of these variations result in a low local CB value at the anode head and tail, making it easier for lithium plating to occur at the corresponding anodes at the beginning and end of the winding of the cathode. Therefore, a protrusion 14 is provided in the end region 11 to reduce the amount of cathode active material in the end region 11 of current collector 1, effectively preventing lithium plating at the corresponding negative electrode in the end region 11 of current collector 1.

[0031] The protrusions 14 on the surface of the current collector 1 can be of various types, including metal protrusions 14, conductive colloid protrusions 14, and conductive polymer protrusions 14. The protrusion structure 14 of the cathode current collector 1 can be obtained by changing the morphology of the intermediate layer of the composite current collector 1, or by applying metal spraying, dispensing / drip coating, coating and drying to the metal layer on the surface of the current collector 1. When setting the protrusions 14, they can be directly set on the body 13 of the current collector 1, and their shape can be adjusted after setting. When the protrusions 14 are metal protrusions 14, the required shape of the current collector 1 can also be obtained by stamping. The protrusion structure 14 of the cathode current collector 1 can be obtained by changing the morphology of the intermediate insulating layer of the composite current collector 1, or by applying metal spraying, dispensing / drip coating, coating and drying to the conductive layer 16 on the surface of the current collector 1, resulting in metal protrusions 14, colloid protrusions 14, conductive polymer protrusions 14, etc. The cathode current collector 1 has a metal protrusion 14 that enhances conductivity and resistance to deformation. The protrusion 14 containing a colloid, such as a conductive adhesive protrusion 14, has good plasticity, ductility, and flexibility. It is softer and more elastic than the metal protrusion 14. The active material in the protrusion 14 area is less likely to be over-pressurized during rolling. In addition, the conductive adhesive can increase liquid retention due to the principle of organic similarity solubility and the ease of making it into a porous structure.

[0032] According to some embodiments of this utility model, the current collector 1 includes an insulating layer 15 and a conductive layer 16. The conductive layer 16 is disposed on the insulating layer 15 to form a coating surface. The insulating layer 15 has protrusions to form protrusions 14 on the coating surface. In the prior art, there is a composite current collector 1, which includes an insulating layer and a conductive layer 16. The conductive layer 16 is disposed on both sides of the insulating layer to form a conductive current collector 1. The conductive layer 16 can also be disposed on one side of the insulating layer. Electroplating, deposition, or other methods can be used to dispose of the conductive layer 16 on the insulating layer. The insulating layer 15 is typically a thin film, which allows for a smaller thickness of the current collector 1. The first layer can also be a metal layer or an alloy conductive layer, thereby improving the overall structural strength of the current collector.

[0033] The composite current collector 1 in the battery cell not only significantly improves battery performance but also demonstrates multiple advantages in practical applications. First, by employing lightweight and highly conductive materials, the composite current collector 1 significantly reduces the overall weight of the battery, which is crucial for applications such as portable electronic devices and electric vehicles. This material allows the battery to maintain high energy density while providing longer driving range and more efficient energy utilization. Second, the mechanical strength and flexibility of the composite current collector 1 are significantly enhanced. This not only helps the battery maintain structural integrity under impact or pressure but also improves the battery's cycle stability under different temperature and environmental conditions, thereby extending battery life. Furthermore, the design flexibility of the composite current collector 1 allows engineers to customize it with specific surface properties according to different electrode materials and battery design requirements, optimizing electrode material adhesion and battery charge / discharge performance. Finally, the use of the composite current collector 1 effectively reduces the battery's internal resistance, meaning the battery can operate more efficiently during charge and discharge, reducing energy loss and providing stronger power output and faster charging speeds. In summary, composite current collectors are playing an increasingly important role in battery technology. They not only improve battery performance but also open up new possibilities for innovative battery design and applications.

[0034] According to some embodiments of this utility model, refer to Figure 3 It also includes a tab 3, which is connected to the current collector 1. The tab 3 in the end region 11 is disposed on the protrusion 14. The tab 3 can be disposed in both the end region 11 and the winding region 12 of the current collector 1. When it is necessary to place the tab 3 in the end region 11, placing the tab 3 on the protrusion 14 can make the connection between the tab 3 and the current collector 1 more convenient and secure.

[0035] According to some embodiments of this utility model, the width of the end region 11 in the first direction is not less than 3 mm. When the width of the end region 11 in the first direction is too small, it is impossible to provide enough protrusions 14, and at the same time, it is impossible to reduce enough cathode active material, thereby failing to effectively prevent lithium plating at the end of the current collector 1. Therefore, the width of the end region 11 in the first direction is set to be not less than 3 mm. Further, the width of the protrusions 14 in the first direction is not less than 0.1 mm, and the width of the protrusions 14 in the third direction is not less than 0.1 mm.

[0036] According to some embodiments of this utility model, the array of protrusions 14 is disposed in the end region 11, and the height of the protrusions 14 in the second direction is not less than 1 μm and not more than 200 μm. When the height of the protrusions 14 in the second direction is too high, the mass of the active material at the edge of the current collector 1 will be too small, thereby affecting the energy density of the battery and reducing the energy density of the battery.

[0037] According to some embodiments of this utility model, the spacing between the protrusions 14 in the first direction is not less than 0.5 mm, and the spacing between the protrusions 14 in the third direction is not less than 0.5 mm, where the third direction is the width direction of the current collector 1. When the spacing between the protrusions 14 is too small, it is difficult to place the active material into the gaps between the protrusions 14 when the cathode active material is placed on the current collector 1 to form the cathode active material layer 2, which can lead to the formation of bubbles in the active material layer. Therefore, the spacing between the protrusions 14 in the first direction and the spacing between the protrusions 14 in the third direction are both limited to not less than 0.5 mm, so that the active material can be fully filled into the gaps between the protrusions 14.

[0038] The formation of air bubbles in the active material layer of a battery is a significant problem. These tiny air pockets not only interfere with internal chemical reactions but also severely impact overall battery performance. When bubbles form in the active material layer, they occupy valuable space, reducing the effective contact area between the active material and the electrolyte. This reduction in contact area directly leads to a decrease in battery charging and discharging efficiency, thus affecting the battery's output power and range. Worse still, bubble accumulation can cause abnormal increases in internal battery pressure. As pressure increases, the battery casing may expand, and in extreme cases, even rupture. This physical damage not only shortens battery life but can also pose safety hazards. In some extreme cases, the continuous accumulation of bubbles can even trigger internal short circuits, leading to overheating and even the risk of combustion or explosion. Therefore, engineers must take a series of measures to prevent and reduce bubble formation during battery design and manufacturing. This includes optimizing battery manufacturing processes, ensuring uniform material mixing, and strictly controlling environmental conditions during battery assembly. Through these meticulous efforts, the negative impacts of bubbles can be significantly reduced, thereby ensuring battery performance and safety.

[0039] According to some embodiments of this utility model, the height of the protrusion 14 in the second direction does not exceed the height of the cathode active material layer 2 in the second direction. When the height of the protrusion 14 in the second direction exceeds the height of the cathode active material layer 2 in the second direction, the protrusion 14 will be exposed. This may damage the separator, leading to an internal short circuit in the battery, or cause compression between the protrusion and the electrode, resulting in a decrease in the energy density of the battery. Therefore, it is necessary to limit the height of the protrusion 14 in the second direction to not exceeding the height of the cathode active material layer 2 in the second direction.

[0040] According to some embodiments of this utility model, in the third direction, the distance between the end region 11 and the edges on both sides of the current collector 1 is not less than 1 mm and not more than 5 mm, where the third direction is the width direction of the current collector 1; when the end region 11 is located at the starting end of the winding of the coating surface, the distance between the end region 11 and the starting edge of the current collector 1 is not less than 3 mm; when the end region 11 is located at the ending end of the winding of the coating surface, the distance between the end region 11 and the ending edge of the current collector 1 is not less than 3 mm. If the end region 11 is too close to the edge of the coating surface, it will affect the structural strength of the current collector 1. Therefore, a certain distance is set between the end region 11 and the edge of the coating surface to avoid the protrusion 14 affecting the structural strength of the current collector 1.

[0041] The lithium-ion-resistant battery according to a second aspect of the present invention includes any of the lithium-ion-resistant cells described in the above embodiments.

[0042] The energy density of a battery cell refers to the energy that can be stored per unit volume or unit mass of the cell. It is usually expressed in watt-hours per liter (Wh / L) for volumetric energy density and in watt-hours per kilogram (Wh / kg) for gravimetric energy density. Higher energy density means the cell can store more electrical energy per unit volume or mass, which is crucial for applications such as portable electronic devices and electric vehicles. How is the energy density of a battery cell calculated? The energy density of a battery cell, i.e., the energy stored per unit volume or unit mass of the battery, is one of the key indicators for measuring battery performance. It is influenced by a variety of complex factors, spanning a wide range of fields from materials science to engineering design. First, the chemical composition of the cell is the core factor affecting energy density. Different cathode materials, such as lithium cobalt oxide (LiCoO2), lithium nickel cobalt manganese oxide (NCM), or lithium iron phosphate (LFP), have different energy storage capacities. Anode materials, such as graphite or silicon-based materials, also affect the overall energy density due to their different electrochemical properties. The choice of electrolyte and the material of the separator are equally important, as they determine the efficiency and safety of ion transport within the battery. Design and manufacturing processes are also crucial factors affecting energy density. The battery's structural design, including electrode thickness, active material loading, and packaging method, significantly impacts energy density. For example, thinner electrodes reduce the use of inactive materials, thus increasing energy density per unit volume. The precision of the manufacturing process, such as coating uniformity, compaction density, and assembly accuracy, all affect battery performance. Furthermore, material quality and purity also have a significant impact on energy density. High-purity materials reduce internal side reactions and improve energy utilization. The microstructure of materials, such as particle size and distribution, also affects the surface area of ​​electrode materials and ion diffusion paths, thereby influencing the battery's charge and discharge performance.

[0043] Lithium plating, a troublesome problem in the lithium-ion battery field, refers to the uneven deposition of lithium ions on the negative electrode surface during battery charging, eventually forming lithium metal dendrites. The appearance of these dendrites poses a significant threat to the battery's health. First, from a safety perspective, lithium dendrite growth is a double-edged sword. It can not only pierce the battery's internal separator, causing direct contact between the positive and negative electrodes, but this contact often has catastrophic consequences. Once a short circuit occurs, the battery's internal temperature will rise sharply, triggering a series of chain reactions, potentially leading to overheating, expansion, or even fire and explosion, posing a significant safety hazard to users. Second, battery life is also significantly reduced due to lithium dendrite formation. The continuous growth of lithium dendrites consumes the battery's precious lithium-ion resources. As lithium ions decrease, the battery's rechargeable cycles and capacity gradually decline. Users will find that a battery that could have lasted for several years may experience significant performance degradation in a very short time. Furthermore, the battery's charging and discharging efficiency is also severely affected. The formation of lithium dendrites increases the battery's internal resistance, making the flow of electrons within the battery less smooth. This increased resistance not only reduces charging speed but also affects power output during discharge, thus lowering the overall battery performance. Finally, the stability of battery performance is also affected by the uneven growth of lithium dendrites. The growth of lithium dendrites can lead to voltage instability during battery use. These voltage fluctuations directly affect the devices powered by the battery, causing them to operate unstably or even shut down unexpectedly. Therefore, lithium plating is a phenomenon that must be strictly controlled and avoided in the design and use of lithium-ion batteries. Battery manufacturers and researchers have been working to reduce or eliminate lithium dendrite formation by improving battery materials, optimizing battery structure, and optimizing charging strategies to ensure battery safety, extend its lifespan, and maintain its performance stability and reliability.

[0044] The embodiments of the present utility model have been described in detail above with reference to the accompanying drawings. However, the present utility model is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present utility model.

Claims

1. A lithium plating-resistant cathode sheet for manufacturing wound battery cells, characterized in that, include: A current collector having at least one coated surface, the coated surface including an end region and a winding region; The end region along the first direction is located at the starting end of the winding of the coating surface, and / or, the end region along the first direction is located at the ending end of the winding of the coating surface; the first direction is the winding direction of the current collector, the current collector includes a body and a protrusion, the protrusion is disposed in the end region, the protrusion protrudes relative to the body in a second direction, the second direction is the orientation of the coating surface; A cathode active material layer is disposed on the coating surface and covers the protrusion.

2. The lithium plating-resistant cathode sheet according to claim 1, characterized in that, The current collector includes a first layer and a second layer, the second layer covering the first layer to form the coating surface, and the first layer having protrusions to form protrusions on the coating surface.

3. The lithium plating-resistant cathode sheet according to claim 1, characterized in that, It also includes a tab connected to the current collector, and the tab in the end region is disposed on the protrusion.

4. The lithium plating-resistant cathode sheet according to claim 1, characterized in that, The width of the end region in the first direction is not less than 3 mm.

5. The lithium plating-resistant cathode sheet according to claim 1, characterized in that, The array of protrusions is disposed in the end region, and the height of the protrusions in the second direction is not less than 1 μm and not more than 200 μm.

6. The lithium plating-resistant cathode sheet according to claim 5, characterized in that, The protrusions are spaced at least 0.5 mm apart in the first direction and at least 0.5 mm apart in a third direction, where the third direction is the width direction of the current collector.

7. The lithium plating-resistant cathode sheet according to claim 1, characterized in that, The height of the protrusion in the second direction does not exceed the height of the cathode active material layer in the second direction.

8. The lithium plating-resistant cathode sheet according to claim 1, characterized in that, The width of the protrusion in the first direction is not less than 0.1 mm, and the width of the protrusion in the third direction is not less than 0.1 mm.

9. The lithium plating-resistant cathode sheet according to claim 1, characterized in that, In the third direction, the distance from the end region to the edges on both sides of the current collector is not less than 1 mm and not more than 5 mm, and the third direction is the width direction of the current collector; When the end region is located at the starting end of the winding of the coating surface, the distance between the end region and the starting edge of the current collector is not less than 3 mm; When the end region is located at the winding end of the coating surface, the distance between the end region and the edge of the winding end of the current collector is not less than 3 mm.

10. A lithium-ion battery with anti-lithium plating properties, characterized in that, The lithium plating-resistant cathode sheet includes any one of claims 1-9.

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