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

Abstract

The utility model provides an anti-precipitation lithium cathode piece and an anti-precipitation lithium battery, comprising: a cathode current collector, the cathode current collector comprises a body and protrusions, the protrusions comprise a first protrusion and / or a second protrusion, the body is provided with at least one coating surface, the first protrusion is arranged on the coating surface, the second protrusion is arranged on the coating surface, and the second protrusion is arranged on the coating surface. One surface, back to the body, of the first bulge is provided with a groove, the groove is used for accommodating a cathode tab, the second bulges are arranged on the coating surface, the second bulges are in one-to-one correspondence with anode tabs, and the corresponding positions of the anode tabs on the cathode current collector are positioned on the second bulges; and a cathode active material layer, wherein the cathode active material layer is arranged on the coating surface and covers the bulge. According to the lithium precipitation prevention cathode plate, lithium precipitation can be effectively prevented from occurring in the peripheral area of the tab of the battery cell.

Description

TECHNICAL FIELD

[0001] The utility model relates to new energy technology field especially relates to a kind of lithium precipitation prevention cathode sheet and lithium precipitation prevention battery. BACKGROUND

[0002] With the continuous progress and innovation of science and technology, people's demand for various intelligent devices is increasing, especially smart phones, computers and other electronic products. The popularity of these devices makes people have higher requirements for the performance and safety of intelligent products. Among many performance indicators, energy density and safety have become the focus of consumers and manufacturers. In order to meet these needs, higher coating weight and compaction are used, and the charging capacity of the system is increasingly challenged, so that the battery is more prone to lithium precipitation. Especially in the tab area of the pole piece, the current density near the tab site is large, the lithium extraction speed of the cathode is greater than the lithium insertion speed of the anode, which leads to poor lithium insertion, and the two tab sites are covered by cathode protective glue and cathode film glue. Lithium ions in the covered area tend to accumulate and precipitate near the edge of the glue paper. Therefore, a new battery is needed to prevent lithium precipitation from occurring at the tab site. SUMMARY

[0003] The utility model aims at at least one of the technical problems existing in the prior art. To this end, the utility model provides a lithium precipitation prevention cathode sheet, which can effectively prevent lithium precipitation around the tab of the battery cell.

[0004] The utility model further provides a lithium precipitation prevention battery.

[0005] According to the lithium precipitation prevention cathode sheet of the first aspect of the utility model, the cathode current collector includes a body and a protrusion, the protrusion includes a first protrusion and / or a second protrusion, at least one coating surface is provided on the body, the first protrusion is provided on the coating surface, a groove is opened on the side of the first protrusion opposite to the body, the groove is used for accommodating the cathode tab, the second protrusion is provided on the coating surface, the second protrusion corresponds to the anode tab one by one, and the corresponding position of the anode tab on the cathode current collector is located on the second protrusion.

[0006] The lithium precipitation prevention cathode sheet has at least the following beneficial effects: the first protrusion is arranged at the position where the cathode tab is arranged close to the cathode current collector, thereby reducing the mass of the cathode active material at the position of the cathode tab of the cathode current collector, i.e., the position where the current density is relatively large, thereby effectively avoiding lithium precipitation around the position of the cathode tab.

[0007] According to some embodiments of the present application, the cathode current collector comprises a first layer and a second layer, the second layer is arranged on the first layer to form the coating surface, and the first layer is provided with a protruding block to form the first protrusion and / or the second protrusion on the coating surface.

[0008] According to some embodiments of the present application, a plurality of first protrusions and / or second protrusions are arranged on the coating surface along a first direction, the first direction is the extension direction of the cathode current collector, and the plurality of first protrusions and / or second protrusions are arranged on the edge of one side of the coating surface.

[0009] According to some embodiments of the present application, a first tab protector is further arranged on the side of the cathode tab opposite to the cathode current collector, and the first tab protector covers the groove.

[0010] According to some embodiments of the present application, the distance between the edge of the first tab protector and the edge of the first protrusion is not less than 1 mm and not more than 5 mm, and the first tab protector does not exceed the projection area of the first protrusion.

[0011] According to some embodiments of the present application, the depth of the groove in a second direction is not less than the thickness of the cathode tab in the second direction, and the second direction is the thickness direction of the cathode current collector.

[0012] According to some embodiments of the present application, the groove penetrates the first protrusion, the cathode current collector is exposed in the groove, and the cathode tab is arranged in the groove and fixedly connected to the cathode current collector.

[0013] According to some embodiments of the present application, a second tab protector is further arranged on the side of the second protrusion opposite to the cathode current collector, and the distance between the edge of the second tab protector and the edge of the second protrusion is not less than 1 mm and not more than 5 mm, and the second tab protector does not exceed the projection area of the second protrusion.

[0014] According to some embodiments of the present application, the first protrusion and / or the second protrusion has a height of not less than 1 μm and not more than 200 μm.

[0015] According to the second aspect of the present application, the lithium precipitation prevention cathode sheet comprises the lithium precipitation prevention cathode sheet according to any one of the above embodiments.

[0016] The additional aspects and advantages of the present application will be given in part in the following description, and will become apparent from the following description, or will be learned by practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 FIG. 1 is a front view of a lithium precipitation prevention cathode sheet according to the present application;

[0018] Figure 2 FIG. 1 is a front view of a lithium precipitation prevention cathode sheet according to the present application;

[0019] Figure 3 FIG. 1 is a front view of a lithium precipitation prevention cathode sheet according to the present application;

[0020] REFERENCE NUMERALS

[0021] 1, cathode current collector; 11, body; 12, first protrusion; 13, second protrusion; 14, groove; 15, first tab protector; 16, second tab protector; 17, first layer; 18, second layer; 2, cathode active material layer; 3, cathode tab. DETAILED DESCRIPTION

[0022] The embodiments of the present application will be described in detail below, and examples of the embodiments are shown in the drawings, wherein the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the drawings are exemplary and are only used to explain the present application, and cannot be understood as a limitation of the present application.

[0023] In the description of the present application, it should be understood that the orientation description, such as the orientation or position relationship indicated by up, down, etc. is based on the orientation or position relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as a limitation of the present application. The device or element indicated is necessarily constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0024] In the description of the present application, the plural means more than two. If there is a description of first, second, etc., it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the sequence of indicated technical features.

[0025] In the description of the utility model, unless otherwise expressly limited, the words such as setting, installing, connecting should be understood broadly, and the skilled person in the art can determine the specific meaning of the above words in the utility model in combination with the specific content of technical scheme.

[0026] In the manufacturing process of the battery, the active material needs to be coated on the current collector to form an active material layer. No matter on the cathode sheet or the anode sheet, the current density near the tab site is large, the cathode lithium extraction speed is greater than the anode lithium insertion speed, which leads to poor lithium insertion, and the two tab sites are covered by the cathode protective glue and the cathode film glue, and the lithium ion migration to the edge of the glue paper in the covered area is easy to gather and precipitate lithium. By reducing the active material of the cathode region around the first protective object and the second protective object covering the two tab sites and the tab protective object, the density of the insertion is reduced, and the lithium precipitation around the tab site is reduced.

[0027] Referring to Figure 1 , Figure 2 and Figure 3 , the anti-lithium precipitation cathode sheet in the first embodiment of the utility model comprises: a cathode current collector 1 and a cathode active material layer 2, the cathode current collector 1 comprises a body 11 and a first protrusion 12, at least one coating surface is arranged on the body 11, the first protrusion 12 is arranged on the coating surface, a groove 14 is arranged on the side of the first protrusion 12 opposite to the body 11, and the groove 14 is used for accommodating the cathode tab 3; the cathode active material layer 2 is arranged on the coating surface and covers the first protrusion 12. Since the cathode tab 3 of the cathode current collector 1 of the anti-lithium precipitation cathode sheet is prone to lithium precipitation, the position of the cathode tab 3 refers to the position of the cathode tab 3 and the peripheral region of the position of the cathode tab 3. Therefore, the first protrusion 12 is arranged around the cathode tab 3, wherein a whole first protrusion 12 can be arranged, and the groove 14 is arranged on the first protrusion 12 to accommodate the cathode tab 3, or the first protrusion 12 can be arranged in multiple parts, and the multiple parts are arranged around the cathode tab 3 to form a groove 14 for accommodating the cathode tab 3. Further, two mutually opposite coating surfaces are arranged on the body 11, the two coating surfaces are coated with the cathode active material, and the cathode tab 3 can be arranged on any coating surface, and the first protrusion 12 is arranged on the coating surface with the cathode tab 3.

[0028] The protrusion type provided on the surface of the cathode current collector 1 can be a metal protrusion, a conductive glue protrusion, a conductive polymer protrusion, etc. The protrusion structure of the cathode current collector 1 can be obtained by changing the morphology of the intermediate layer of the composite current collector, or can be obtained by using metal spraying, glue dispensing / dripping, coating and drying, etc. on the surface metal layer of the cathode current collector 1. Among them, the protrusion can be directly provided on the body 11 of the current collector when the protrusion is provided, and the shape of the protrusion is trimmed after the protrusion is provided. When the protrusion is a metal protrusion, the shape required by the current collector can also be obtained by stamping. The protrusion structure of the cathode current collector 1 can be obtained by changing the morphology of the intermediate insulating layer of the composite current collector, or can be obtained by using metal spraying, glue dispensing / dripping, coating and drying, etc. on the surface conductive layer of the current collector to obtain metal protrusions, glue protrusions and conductive polymer protrusions. The protrusion of the preset metal of the cathode current collector 1 can enhance the conductivity and the anti-deformation effect; the setting of the glue protrusion such as the conductive glue protrusion has the advantages of good plasticity, ductility and flexibility, softness and elasticity, and the active substance in the protrusion area is not easy to be over-pressed during rolling, etc. Moreover, the conductive glue can increase the liquid preservation due to the similar phase solubility principle and the easy-to-make porous structure.

[0029] According to some embodiments of the present application, the cathode current collector 1 comprises a first layer 17 and a second layer 18, the second layer 18 is arranged on the first layer 17 to form a coating surface, and the first layer 17 is provided with a protrusion to form a first protrusion 12 on the coating surface. In the prior art, there is a composite current collector, and the composite current collector comprises an insulating layer, i.e. the first layer 17, and a conductive layer, i.e. the second layer 18, and the conductive layer is arranged on both sides of the insulating layer to form a current collector that can conduct electricity. The conductive layer can also be arranged on one side of the insulating layer. When the conductive layer is arranged on the insulating layer, electroplating, deposition and other methods can be used. The insulator is usually a thin film, which can make the thickness of the current collector smaller. The first layer can also be a metal layer or an alloy conductive layer, thereby improving the overall structural strength of the current collector.

[0030] The composite current collector of the battery cell not only brings significant improvement in battery performance, but also exhibits multiple advantages in practical applications. First, the composite current collector significantly reduces the overall weight of the battery by using lightweight and excellent conductive materials, which is crucial for applications such as portable electronic devices and electric vehicles. The use of such materials enables 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 are significantly enhanced, which not only helps the battery maintain structural integrity when subjected to impact or pressure, but also improves the cycling stability of the battery under different temperature and environmental conditions, thereby extending the service life of the battery. In addition, the design flexibility of the composite current collector allows engineers to customize the current collector with specific surface properties according to different electrode materials and battery design requirements, to optimize the adhesion of electrode materials and the charge-discharge performance of the battery. Finally, the use of composite current collectors can effectively reduce the internal resistance of the battery, which means that the battery can work with higher efficiency during charging and discharging, reducing energy loss and providing stronger power output and faster charging speed. In summary, the composite current collector plays an increasingly important role in battery technology, not only improving the performance of the battery, but also opening up new possibilities for innovative design and application of the battery.

[0031] According to some embodiments of the present application, a plurality of first protrusions 12 are arranged on the coated surface along the first direction, and the first direction is the extension direction of the cathode current collector 1. The plurality of first protrusions 12 are arranged on the edge of one side of the coated surface. The cathode tab 3 is arranged on the edge of one side of the coated surface, which is more easily arranged in the groove 14 on the first protrusion 12, so the first protrusion 12 is arranged on one side of the coated surface. The first protrusion 12 is arranged on the edge, so that the cathode tab 3 arranged in the groove 14 can directly extend out of the outside of the cathode current collector 1.

[0032] According to some embodiments of the present application, a first tab protector 15 is arranged on the side of the cathode tab 3 opposite the cathode current collector 1, and the first tab protector 15 covers the groove 14. The first tab protector 15 is an insulator, which can be protective glue and adhesive paper, etc. The tab protection glue is arranged to avoid the cathode tab 3 and burrs on the first protrusion 12 from piercing the diaphragm and causing short circuit. Further, the distance between the edge of the first tab protector 15 and the edge of the first protrusion 12 is not less than 1mm and not more than 5mm, and the first tab protector does not exceed the projection area of the first protrusion. At the same time, the distance between the edge of the first tab protector 15 and the edge of the groove is not less than 2mm. Thus, the firmness of the first tab protector 15 is ensured.

[0033] According to some embodiments of the present application, the depth of the groove 14 in the second direction is not less than the thickness of the cathode tab 3 in the second direction, and the second direction is the thickness direction of the cathode current collector 1. The groove 14 can completely accommodate the thickness of the cathode tab 3, avoiding the cathode tab 3 from protruding from the groove 14, so as to avoid affecting the flatness of the battery cell.

[0034] According to some embodiments of the present application, the groove 14 penetrates the first protrusion 12, the cathode current collector 1 is exposed in the groove 14, and the cathode tab 3 is arranged in the groove 14 and fixedly connected to the cathode current collector 1. By arranging the cathode tab 3 directly on the cathode current collector 1, the thickness of the cathode tab 3 can be increased, and a thicker cathode tab 3 can be used.

[0035] According to some embodiments of the present application, the cathode current collector 1 comprises a second protrusion 13, the second protrusion 13 is arranged on the coated surface, the second protrusion 13 corresponds to the anode tab one by one, and the position corresponding to the anode tab on the cathode current collector 1 is located on the second protrusion 13. The position corresponding to the anode tab on the lithium precipitation prevention cathode sheet is also prone to lithium precipitation phenomenon. Therefore, the second protrusion 13 is arranged at the corresponding position, so as to avoid the occurrence of lithium precipitation phenomenon.

[0036] According to some embodiments of the present application, the second tab protector 16 is arranged on the side of the second protrusion 13 opposite to the cathode current collector 1, the second tab protector 16 can reduce the risk of direct short circuit of the cathode after the anode tab burr pierces the diaphragm, so as to make the battery safer. The second tab protector 16 is an insulator, which can be protective glue and adhesive paper. Further, the distance between the edge of the second tab protector 16 and the edge of the second protrusion 13 is not less than 1mm and not more than 5mm, and the second tab protector does not exceed the projection area of the second protrusion. In this way, the lithium embedding density of the anode tab corresponding to the cathode region is reduced, and the lithium precipitation of the anode tab corresponding region is improved.

[0037] According to some embodiments of the present application, the height of the first protrusion 12 and / or the second protrusion 13 is not less than 1μm and not more than 200μm. When the height of the first protrusion 12 is too high, the mass of the cathode active material will be too small, thereby affecting the energy density of the battery, and reducing the energy density of the battery. If the height of the first protrusion 12 is too low, the lithium precipitation phenomenon cannot be effectively avoided.

[0038] The lithium precipitation prevention battery according to the second aspect of the present application comprises the lithium precipitation prevention cathode sheet according to any one of the above embodiments.

[0039] The energy density of an electric cell refers to the amount of energy that can be stored per unit volume or mass of the cell. It is typically expressed in terms of watt-hours per liter (Wh / L) for volumetric energy density and watt-hours per kilogram (Wh / kg) for gravimetric energy density. Higher energy density means that the cell can store more electrical energy in the same volume or mass, which is crucial for applications such as portable electronic devices and electric vehicles. How is the energy density of an electric cell calculated? The energy density of an electric cell, which refers to the amount of energy that can be stored per unit volume or mass of the battery, is one of the key indicators of battery performance. It is influenced by a variety of complex factors that span a wide range of fields from material science to engineering design. First and foremost, the chemical composition of the cell is a core factor that affects 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 capabilities. Similarly, 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 also crucial, as they determine the efficiency and safety of ion transport within the battery. Design and manufacturing processes are also important aspects that affect energy density. The structural design of the battery, including the thickness of the electrodes, the loading amount of active materials, and the packaging method of the battery, can significantly affect the energy density. For example, thinner electrodes can reduce the use of non-active materials, thereby increasing the energy density per unit volume. The precision of manufacturing processes, such as the uniformity of coating, the compaction density, and the accuracy of assembly, can also affect the performance of the battery. In addition, the quality and purity of materials also have a non-negligible impact on energy density. High-purity materials can reduce side reactions within the battery and improve energy utilization. The microstructure of materials, such as particle size and distribution, can also affect the surface area of electrode materials and ion diffusion paths, thereby affecting the charge and discharge performance of the battery.

[0040] Battery lithium precipitation, a thorny problem in the field of lithium-ion batteries, refers to the uneven deposition of lithium ions on the surface of the negative electrode during the charging process, eventually forming lithium metal dendrites. The presence of these dendrites poses a great threat to the health of the battery. First, from the perspective of safety, the growth of lithium dendrites is like a double-edged sword. It not only may pierce the separator inside the battery, causing direct contact between the positive and negative electrodes, but this contact often accompanies catastrophic consequences. Once a short circuit occurs, the temperature inside the battery will rise sharply, triggering a series of chain reactions that may eventually lead to battery overheating, swelling, and even fire and explosion, posing a great safety hazard to users. Second, the life of the battery will also be greatly reduced due to the formation of lithium dendrites. The continuous growth of lithium dendrites will consume valuable lithium ion resources inside the battery, and as the lithium ions decrease, the number of chargeable times and capacity of the battery will gradually decrease. Users will find that the battery that can be used for several years may experience significant performance degradation in a short period of time. In addition, the charging and discharging efficiency of the battery will also be severely affected. The formation of lithium dendrites increases the internal resistance of the battery, making the flow of electrons inside the battery no longer smooth. This increase in resistance not only reduces the charging speed, but also affects the power output during discharging, thus reducing the overall performance of the battery. Finally, the stability of the battery performance will also be affected by the uneven growth of lithium dendrites. The growth of lithium dendrites may cause voltage instability in the battery during use, and this voltage fluctuation will directly affect the equipment powered by the battery, making it unstable and even causing unexpected shutdowns. Therefore, battery lithium precipitation 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 the formation of lithium dendrites by improving battery materials, optimizing battery structure and charging strategies, etc., to ensure the safety of the battery, extend its service life, and maintain its performance stability and reliability.

[0041] The embodiments of the utility model are explained in detail above in combination with the drawings, but the utility model is not limited to the above-mentioned embodiments, and various changes can be made within the knowledge range of ordinary skilled in the art without departing from the purpose of the utility model.

Claims

1. A lithium precipitation-preventing cathode sheet characterized by comprising: The cathode sheet includes: a cathode current collector including a body and protrusions, the body being provided with at least one coated surface, the first protrusions being provided on the coated surface, the first protrusions being provided with a groove on a side opposite to the body, the groove being used for accommodating a cathode tab, the second protrusions being provided on the coated surface, the second protrusions corresponding to anode tabs one by one, the anode tabs being located on the second protrusions at corresponding positions on the cathode current collector; a cathode active material layer provided on the coated surface and covering the protrusions.

2. The lithium plating prevention cathode sheet according to claim 1, characterized by The cathode current collector includes a first layer and a second layer, the second layer being provided on the first layer to form the coated surface, the first layer being provided with a bump to form the first protrusions and / or the second protrusions on the coated surface.

3. The lithium plating prevention cathode sheet according to claim 1, characterized by The coated surface is provided with a plurality of the first protrusions and / or the second protrusions in a first direction, the first direction being an extension direction of the cathode current collector, and the plurality of the first protrusions and / or the second protrusions are all provided on an edge of one side of the coated surface.

4. The lithium plating prevention cathode sheet according to claim 1, characterized by The cathode sheet further includes a first tab protector provided on a side of the cathode tab opposite to the cathode current collector, the first tab protector covering the groove.

5. The lithium plating prevention cathode sheet according to claim 4, characterized by An edge of the first tab protector is located at a distance of not less than 1 mm and not more than 5 mm from an edge of the first protrusion, and the first tab protector does not exceed a projected area of the first protrusion.

6. The lithium plating prevention cathode sheet according to claim 1, characterized by A depth of the groove in a second direction is not less than a thickness of the cathode tab in the second direction, the second direction being a thickness direction of the cathode current collector.

7. The lithium plating prevention cathode sheet according to claim 1, characterized by The groove penetrates the first protrusion, the cathode current collector being exposed in the groove, and the cathode tab is provided in the groove and fixedly connected to the cathode current collector.

8. The lithium plating prevention cathode sheet according to claim 1, characterized by, The cathode sheet further includes a second tab protector provided on a side of the second protrusion opposite to the cathode current collector, an edge of the second tab protector being located at a distance of not less than 1 mm and not more than 5 mm from an edge of the second protrusion, and the second tab protector does not exceed a projected area of the second protrusion.

9. The lithium plating prevention cathode sheet according to claim 1, characterized by, A height of the first protrusion and / or the second protrusion is not less than 1 μm and not more than 200 μm.

10. A lithium precipitation preventing battery, characterized by The cathode sheet includes the lithium precipitation prevention cathode sheet according to any one of claims 1-9.

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