Pole piece and lithium ion battery

Abstract

The utility model discloses a pole piece which comprises a current collector, a tab welding area and a non-tab welding area which are connected with each other are formed on at least one surface of the current collector, a safety coating is coated on at least one surface of the current collector, a plurality of through holes are formed on the safety coating, and an active substance layer is coated on one surface, back to the current collector, of the safety coating. At least part of the active material layer penetrates through the through holes to be connected with the current collector, and the number of the through holes near the tab welding area is larger than that of the through holes near the non-tab welding area. Therefore, the safety of the battery is ensured, the negative influence on the performance of the battery is avoided, and the long-time stable operation of the battery under efficient and safe conditions is ensured. In addition, the utility model also discloses a lithium ion battery.

Description

Technical Field

[0001] This utility model relates to the field of lithium battery technology, and in particular to an electrode and a lithium-ion battery. Background Technology

[0002] With the widespread use of lithium-ion batteries, their safety has become increasingly important. During use, lithium-ion batteries may overheat due to internal or external short circuits, which can lead to safety accidents such as combustion and explosion.

[0003] To improve the safety of lithium-ion batteries, a safety coating is typically applied to the surface of the current collector. This coating primarily serves to isolate the electrode materials, preventing unnecessary chemical reactions between the active materials and the current collector, thereby reducing potential safety hazards within the battery.

[0004] While existing safety coating technologies have shown some effectiveness in improving the safety of lithium-ion batteries, they also have significant drawbacks. Because the safety coating hinders direct contact between the active material and the current collector, the electron transport path becomes longer, increasing the resistance encountered when current flows and leading to a decrease in the overall conductivity of the battery. Utility Model Content

[0005] The main objective of this invention is to propose an electrode sheet that aims to solve the problem of decreased overall conductivity of batteries caused by safety coatings.

[0006] To achieve the above objectives, this utility model proposes an electrode sheet, which includes:

[0007] A current collector, wherein at least one surface of the current collector has a connected tab welding area and a non-tab welding area;

[0008] A safety coating is applied to at least one surface of the current collector, and the safety coating has a plurality of through holes.

[0009] An active material layer is coated on the side of the safety coating facing away from the current collector, and at least a portion of the active material layer passes through the plurality of through holes and is connected to the current collector;

[0010] The number of through holes near the tab welding area is greater than the number of through holes near the non-tab welding area.

[0011] In some embodiments, the number of through holes gradually decreases from the tab welding area to the non-tab welding area.

[0012] In some embodiments, the resistance of the safety coating is greater than the resistance of the active material layer.

[0013] In some embodiments, the volume of the active material layer within the plurality of through holes is less than or equal to the volume of the active material coated on the surface of the safety coating.

[0014] In some embodiments, the inner diameter of the plurality of through holes is greater than 0.5 mm and less than 2 mm.

[0015] In some embodiments, the plurality of vias are formed on the security coating using a selective mask coating process or a laser processing process.

[0016] In some embodiments, the sum of the projected areas of the plurality of through holes on the current collector is less than or equal to the surface area of ​​the safety coating.

[0017] In some embodiments, the sum of the areas of the active material layer in contact with the current collector within the through-hole is equal to the area of ​​the safety coating in contact with the current collector.

[0018] In some embodiments, the shape of the plurality of through holes is at least one of circular, elliptical, and polygonal.

[0019] This utility model further proposes a lithium-ion battery, including the electrode sheets of the aforementioned embodiments, wherein the battery cell is a stacked battery cell or a wound battery cell.

[0020] The beneficial effects of this utility model's technical solution are as follows: By setting through holes in the safety coating, some active materials can be directly connected to the current collector, thereby reducing the resistance caused by the presence of the safety coating and ensuring that the battery's conductivity is not affected. Simultaneously, increasing the number of through holes near the electrode welding area effectively reduces the internal resistance in this area, avoiding localized overheating caused by current concentration. Thus, both battery safety and negative impacts on battery performance are ensured, guaranteeing stable long-term operation of the battery under efficient and safe conditions. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the electrode sheet in one embodiment of the present invention;

[0022] Figure 2 This is a schematic diagram of the electrode structure in another embodiment of the present invention;

[0023] Figure 3 A schematic diagram showing the distribution of through holes in one embodiment of the present invention is shown;

[0024] Figure 4 A schematic diagram showing the distribution of through holes in another embodiment of the present invention is shown;

[0025] Figure 5 A schematic diagram showing the distribution of through holes in another embodiment of the present invention is shown.

[0026] Explanation of icon numbers:

[0027] 100. Current collector; 102. Electrode welding area; 104. Non-electrode welding area;

[0028] 200, safety coating; 200a, through-hole;

[0029] 300. Active substance layer.

[0030] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0031] The solutions in the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this utility model.

[0032] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0033] It should also be noted that when a component is described as "fixed to" or "set on" another component, it can be directly on the other component or there may be an intervening component present. When a component is described as "connected to" another component, it can be directly connected to the other component or there may be an intervening component present.

[0034] Furthermore, the use of terms such as "first" and "second" in this utility model is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this utility model.

[0035] A safety coating is applied to at least one surface of the current collector to isolate the active material layer from direct contact with the current collector, thus avoiding the risk of short circuits in lithium-ion batteries under certain circumstances (e.g., preventing instantaneous heat generation from aluminum foil burrs and anode active material during a short circuit, which could lead to cell fire). However, this technology results in a high internal resistance due to the high internal resistance of the safety coating itself and the high contact resistance between the cathode active material and the safety coating. While ensuring safety, the performance of the lithium-ion battery also decreases. Therefore, in this embodiment, holes are drilled in the safety coating to allow the active material layer to pass through and connect to the current collector. The number of through-holes near the tab welding area is greater than that outside the tab welding area. This is because the current is higher near the tab; if the resistance in this area is too high, more heat will be generated when the current flows through, leading to localized overheating. Therefore, increasing the number of through-holes near the tab welding area can effectively reduce internal resistance and improve battery performance. See [reference needed] for details. Figure 1 and Figure 2 An embodiment of this utility model proposes an electrode sheet, which includes:

[0036] The current collector 100 has at least one surface having an interconnected tab welding area 102 and a non-tab welding area 104102.

[0037] Safety coating 200 is applied to at least one surface of current collector 100, and a plurality of through holes 200a are formed on safety coating 200.

[0038] An active material layer 300 is coated on the side of the safety coating 200 that is opposite to the current collector 100, and at least a portion of the active material layer 300 passes through a plurality of through holes 200a and is connected to the current collector 100.

[0039] Among them, the number of through holes 200a near the tab welding area 102 is greater than the number of through holes 200a near the non-tab welding area 104102.

[0040] In this embodiment, the electrode includes a current collector 100, a safety coating 200, and an active material layer 300. The main function of the current collector 100 is to act as a current conduction channel, efficiently transferring electrons generated in the active material layer 300 to the external circuit. Regarding the material selection, the current collector 100 can typically be made of a metal material with good conductivity. Aluminum foil is generally used when used as the positive electrode, while copper foil is used when used as the negative electrode. These materials not only have good conductivity but also excellent mechanical strength and corrosion resistance.

[0041] The safety coating 200 serves to isolate the current collector 100 from the active material layer 300, preventing unnecessary chemical reactions during battery use and reducing the risk of short circuits. The safety coating 200 can be composed of heat-resistant and chemically resistant insulating materials, such as lithium iron phosphate, ceramic particles, or a mixture of both, along with a binder (PVDF or PMMA, etc.). To reduce the internal resistance introduced by the safety coating 200, this embodiment incorporates multiple through-holes 200a. These through-holes 200a allow some of the active material to pass through the safety coating 200 and directly contact the current collector 100, thereby reducing resistance in the current conduction path.

[0042] The main function of the active material layer 300 is to provide energy storage and release for the battery. It is usually composed of electrochemical active materials, such as lithium iron phosphate and ternary materials (NCM / NCA) for the positive electrode, or graphite and silicon-carbon composite materials for the negative electrode.

[0043] It should be noted that there are two ways to arrange the tab welding area 102 and the non-tab welding area 104102. One way is that the two ends of the current collector 100 are the non-tab welding area 104102 and the middle is the tab welding area 102. The other way is that one end of the current collector 100 is the non-tab welding area 104102 and the other end is the tab welding area 102. In this embodiment, the latter is used as an example.

[0044] In this embodiment, the movement of lithium ions and electrons is optimized to ensure safety and improve battery performance. When the battery is charging, lithium ions are extracted from the active material layer 300 of the negative electrode and migrate through the electrolyte to the active material layer 300 of the positive electrode. Simultaneously, electrons are transferred through the current collector 100 to the external circuit and ultimately reach the positive electrode. The safety coating 200 effectively isolates the active material layer 300 from the current collector 100, preventing short circuits and other adverse reactions. However, since the safety coating 200 itself has a relatively high resistance, directly covering the surface of the current collector 100 would reduce electron conduction efficiency. Therefore, by creating through-holes 200a in the safety coating 200, a portion of the active material layer 300 can pass through the through-holes 200a and directly connect to the current collector 100. This retains the protective function of the safety coating 200 while reducing resistance in the current conduction path, thus improving the overall performance of the battery. In the tab welding area 102, due to the high current density in this area, increasing the number of through holes 200a can reduce the internal resistance of this area, prevent local overheating caused by current concentration, and thus improve the safety and stability of the battery.

[0045] The beneficial effects of this invention are that by providing through holes 200a on the safety coating 200, at least a portion of the active material layer 300 can be directly connected to the current collector 100, thereby reducing the resistance caused by the presence of the safety coating 200 and ensuring that the conductivity of the battery is not affected. Simultaneously, increasing the number of through holes 200a near the electrode welding area 102 effectively reduces the internal resistance in this area, avoiding localized overheating caused by current concentration. Thus, both battery safety and negative impacts on battery performance are ensured, guaranteeing stable long-term operation of the battery under efficient and safe conditions.

[0046] Further reading Figure 2 In addition to the aforementioned embodiments where a safety coating 200 and an active material layer 300 are provided on at least one surface of the current collector 100, this embodiment proposes a design in which the safety coating 200 and the active material layer 300 are coated on both surfaces of the current collector 100. By providing coatings on both the front and back sides of the current collector 100, the conductivity and overall energy density of the battery are further improved.

[0047] In this embodiment, the arrangement of the through holes 200a is consistent with that in the previous embodiment, ensuring the accuracy and consistency of the through holes 200a, thereby making the battery structure balanced and the conductive path more stable. This double-sided coating design helps to improve the utilization efficiency of the current collector 100, improve the output performance of the battery, while maintaining the safety and reliability of the structure.

[0048] This design, as a supplement to the aforementioned embodiments, provides a lithium-ion battery structure with higher conductivity and energy density.

[0049] See Figures 1 to 3 In this embodiment, the number of through holes 200a gradually decreases from the tab welding area 102 to the non-tab welding area 104102.

[0050] This embodiment mainly adopts a method of gradually transitioning the number of through holes 200a on the safety coating 200 of the current collector 100 to improve the performance and safety of the lithium-ion battery.

[0051] Specifically, taking a current collector 100 as a flat, elongated strip, with one end being the tab welding area 102 and the other end being the non-tab welding area 104102, the vias 200a are densely distributed near the tab welding area 102 to ensure a large current demand and low internal resistance in the tab region. The design of these vias 200a allows the active material to connect more directly and effectively to the current collector 100, reducing resistance and improving electron conduction efficiency.

[0052] As the area moves further away from the tab welding region 102 and closer to the non-tab welding region 104102, the density of the vias 200a gradually decreases. This arrangement of vias 200a creates a gradual transition from the tab welding region 102 to the non-tab welding region 104102, optimizing the overall function of the safety coating 200. It retains the low internal resistance requirement of the current concentration area while reducing unnecessary structural complexity.

[0053] By employing this gradually transitioning arrangement of through-holes 200a, this embodiment significantly reduces the resistance of the tab welding area 102 while maintaining the overall mechanical strength of the current collector 100 and the insulating protection function of the safety coating 200, thus avoiding heat generation problems caused by localized current concentration. Furthermore, the reduction in through-holes 200a in the non-tab welding area 104102 ensures the stability of the overall electrode structure and reduces the complexity of the manufacturing process.

[0054] In some embodiments, the resistance of the safety coating 200 is greater than that of the active material layer 300. In this embodiment, the material selection and structural design of the safety coating 200 are intended to provide insulating protection for the current collector 100 and the active material layer 300, but due to its inherent physical properties, the resistance of the safety coating 200 is typically high.

[0055] This higher resistance can effectively prevent short circuits inside the battery, but it may also increase the overall internal resistance of the battery, thus affecting its charge and discharge performance. Therefore, in order to minimize resistance while ensuring safety, other optimization measures are usually adopted on the safety coating 200, such as creating through holes 200a to allow the active material layer 300 to be directly connected to the current collector 100, thereby reducing the resistance in the current conduction path.

[0056] In some embodiments, the volume of the active material layer 300 within the plurality of through-holes 200a is less than or equal to the volume of the active material coated on the surface of the safety coating 200. This design optimizes the conductivity and overall performance of the battery by adjusting the volume ratio of the active material within the through-holes 200a to that on the surface of the safety coating 200.

[0057] In designs where the volume of the active material layer 300 within the through-hole 200a is smaller than the volume of the active material coated on the surface of the safety coating 200, the active material within the through-hole 200a may not be completely filled. The advantage of this design is that it effectively reduces the pressure on the active material within the through-hole 200a, preventing excessive mechanical stress caused by volume changes during battery charging and discharging, which could damage the structure surrounding the through-hole 200a. Furthermore, reducing the filling volume within the through-hole 200a ensures better ion channels within the electrode, which helps improve electrolyte wetting and lithium-ion transport efficiency, thereby enhancing the battery's cycle performance.

[0058] In the scheme where the volume of the active material layer 300 within the through-hole 200a is equal to the volume of the active material coated on the surface of the safety coating 200, the volumes of the active material layer 300 within the through-hole 200a and on the surface of the safety coating 200 are identical. The advantage of this design is that it ensures the uniformity of the battery structure, reduces the risk of uneven current distribution within the electrodes, and thus reduces heat generation problems caused by localized current concentration. Equal filling also enhances the connection strength between the active material and the current collector 100, ensuring a stable electron conduction path between them during high-rate charge and discharge, further improving the battery's output power.

[0059] By employing a design where the volume of active material within the through-hole 200a is less than or equal to the volume of active material coated on the surface of the safety coating 200, this embodiment optimizes battery performance under different operating conditions. The smaller volume effectively reduces mechanical stress and enhances battery cycle stability, while the equal volume contributes to uniform current distribution, improving battery output power and stability.

[0060] The safety coating 200 of the lithium-ion battery has through-holes 200a. These through-holes 200a are designed to allow the active material to partially pass through the safety coating 200 and directly contact the current collector 100, thereby optimizing the current conduction path. However, the inner diameter of the through-holes 200a is crucial to the overall performance of the battery. If the through-holes 200a are too large, they will weaken the mechanical strength of the safety coating 200 and reduce its protection of the internal components of the battery; while if the through-holes 200a are too small, they may limit the direct contact area between the active material and the current collector 100, resulting in insufficient conductivity and affecting the battery performance. Therefore, in this embodiment, the inner diameter of the multiple through-holes 200a is greater than 0.5 mm and less than 2 mm.

[0061] Specifically, the inner diameter of the through-hole 200a being greater than 0.5 mm ensures sufficient active material to contact the current collector 100 through the through-hole 200a, reducing resistance and improving the battery's conductivity. The larger aperture allows for smoother electron transport, thereby reducing the battery's internal resistance and increasing its output power and charge / discharge efficiency.

[0062] An inner diameter of less than 2mm can maintain the structural integrity of the safety coating 200, ensuring that while providing a current path, it still has sufficient mechanical strength to protect the internal structure of the battery and prevent damage caused by expansion and contraction or external stress during charging and discharging.

[0063] Setting the diameter of the through-hole 200a between 0.5mm and 2mm is in line with existing manufacturing processes, facilitating mass production and precise diameter control. This diameter range ensures that the fabrication of the through-hole 200a does not add excessive complexity to the process while maintaining high efficiency and consistency in production.

[0064] By setting the inner diameter of the multiple through holes 200a to be greater than 0.5 mm and less than 2 mm, this embodiment achieves a significant improvement in battery performance. Within this diameter range, the through holes 200a can provide sufficient contact area for the active material to optimize conductivity while maintaining the mechanical strength of the safety coating 200, ensuring the stability and safety of the battery. Furthermore, the feasibility of the manufacturing process was considered to ensure high machining accuracy and controllable cost for the through holes 200a.

[0065] Overall, this embodiment, through a reasonable design of the 200a inner diameter of the through hole, balances the high efficiency, safety, and manufacturing cost of lithium-ion batteries, providing an effective solution for optimizing the overall performance of the battery.

[0066] There are various ways to form through-holes 200a. For example, multiple through-holes 200a can be formed on the safety coating 200 using selective mask coating or laser processing.

[0067] In this embodiment, the plurality of through-holes 200a on the safety coating 200 can be formed in a variety of different ways, including selective mask coating and laser processing. The formation of these through-holes 200a is designed to ensure the accuracy and consistency of the through-holes 200a, while improving production efficiency and battery performance.

[0068] In a selective mask coating process, before applying the safety coating 200 to the current collector 100, a mask is placed at a predetermined position, followed by the coating process. After coating, the mask is removed, thereby forming vias 200a on the safety coating 200. The advantages of this process are its relatively simple flow, suitability for mass production of large areas with multiple vias 200a, and ability to ensure the accuracy of the position and size of the vias 200a. Furthermore, the mask process allows for flexible control of the number and distribution of vias 200a by adjusting the shape and position of the mask.

[0069] Laser processing is a technique that uses a high-precision laser beam to drill holes in the safety coating 200. In this embodiment, laser processing can precisely form multiple through holes 200a directly on the safety coating 200. The advantages of laser processing lie in its extremely high flexibility and precision, making it particularly suitable for forming small-diameter through holes 200a, and for situations where the position of the through holes 200a is critical.

[0070] By employing selective masking or laser processing to form multiple vias 200a, this embodiment achieves an optimal solution for various application requirements. Selective masking ensures consistent mass production of the vias 200a and reduces production costs, making it ideal for large-scale manufacturing. Laser processing, on the other hand, offers extremely high precision and flexibility, suitable for situations with stringent requirements on the position and size of the vias 200a, thereby ensuring battery performance and reliability.

[0071] To ensure that the volume of the active material layer 300 within the through-hole 200a is less than or equal to the volume of the active material layer 300 coated on the surface of the safety coating 200, in this embodiment, the sum of the projected areas of the plurality of through-holes 200a on the current collector is less than or equal to the surface area of ​​the safety coating 200. The aim is to maintain the battery's conductivity and performance while also ensuring structural stability and ease of manufacturing.

[0072] In this embodiment, the sum of the projected areas of the multiple through holes 200a on the current collector is set to be less than or equal to the surface area of ​​the safety coating 200. This design ensures a reasonable proportional relationship between the active material layer 300 inside the through hole 200a and the active material layer 300 on the surface of the safety coating 200. When the volume of active material inside the through hole 200a is small, the problem of increased local pressure caused by uneven or overfilled active material can be effectively avoided, reducing the mechanical stress generated by volume changes during battery charging and discharging.

[0073] When the sum of the projected areas of the through holes 200a on the current collector is large, too many holes will weaken the structural integrity of the safety coating 200. Therefore, controlling the sum of the projected areas of the through holes 200a on the current collector to be less than or equal to the surface area of ​​the safety coating 200 helps maintain the mechanical strength of the safety coating 200 and avoids material breakage or peeling problems caused by too many holes.

[0074] By designing the sum of the projected areas of multiple through holes 200a on the current collector to be less than or equal to the surface area of ​​the safety coating 200, a dual improvement in battery performance and safety is achieved. On the one hand, the reasonable sum of the projected areas of the through holes 200a allows for effective distribution of active materials, reducing resistance and improving the battery's energy output efficiency; on the other hand, this design ensures the mechanical strength of the safety coating 200, reducing safety hazards caused by coating breakage.

[0075] In some embodiments, the sum of the areas of the active material layer 300 in contact with the current collector 100 within the through hole 200a is equal to the area of ​​the safety coating 200 in contact with the current collector 100.

[0076] In this embodiment, the contact area between the active material layer 300 and the current collector 100 is designed to be equal to the contact area between the safety coating 200 and the current collector 100. This equal area design helps maintain a uniform current distribution within the battery, avoiding problems such as electrode overheating or uneven electrochemical reactions caused by excessive local current density. By making the contact areas of the active material layer 300 and the safety coating 200 equal, it is possible to ensure similar resistance and conductivity characteristics in various regions along the current conduction path, thereby improving the overall performance of the battery.

[0077] Specifically, by ensuring that the contact area between the active material layer 300 and the current collector 100 is equal to the contact area between the safety coating 200 and the current collector 100, it is possible to ensure that the current is uniformly distributed on the electrode surface. This helps reduce current concentration in localized areas, thereby reducing the risk of overheating and improving battery safety and lifespan.

[0078] The equal-area contact design can provide a balanced force distribution in the physical structure, avoid mechanical stress concentration caused by uneven contact area, thereby preventing the active material layer 300 from falling off or the current collector 100 from deforming, and ensuring the stability of the battery structure.

[0079] See Figure 3 , Figure 4 and Figure 5 In this embodiment, the shape of the plurality of through holes 200a is at least one of circular, elliptical and polygonal.

[0080] In this embodiment, the shape of the plurality of through holes 200a on the safety coating 200 can be at least one of circular, elliptical, and polygonal shapes. Different shapes of through holes 200a designs help meet the diverse requirements of lithium-ion batteries in terms of conductivity, mechanical strength, and manufacturing feasibility.

[0081] Specifically, the circular through-hole 200a features good symmetry and uniform stress distribution. During manufacturing, the shape of the circular through-hole 200a is easily processed and controlled, making it suitable for most common applications. The circular through-hole 200a effectively reduces the resistance between the current collector 100 and the active material, thereby improving conductivity while maintaining the overall strength of the safety coating 200.

[0082] Compared to the circular through-hole 200a, the elliptical through-hole 200a has a longer contact area, increasing the contact area between the active material and the current collector 100, thereby further reducing resistance and improving conductivity. The elliptical through-hole 200a design can also enhance the distribution of the active material in specific areas, making it suitable for applications requiring increased current carrying capacity.

[0083] The polygonal through-hole 200a offers flexible shape design, including shapes such as triangles, rectangles, or hexagons. These shapes can be selected based on the specific battery structure design to maximize the contact efficiency between the current collector 100 and the active material while ensuring the mechanical strength of the coating. The polygonal through-hole 200a is suitable for applications requiring enhanced conductivity in specific directions, such as those needing to increase current density in certain areas.

[0084] In this embodiment, the shapes of the multiple through holes 200a can be designed as at least one of circular, elliptical, and polygonal shapes, aiming to achieve an optimal performance balance through different shapes of through holes 200a. Circular through holes 200a provide good mechanical strength and manufacturing stability, elliptical through holes 200a increase the contact area of ​​the current path, while polygonal through holes 200a can adjust conductivity and structural characteristics according to requirements. Simultaneously, the combination design of different shapes can optimize the current distribution inside the battery, improve the utilization rate of active materials, and maintain the overall structural stability of the battery.

[0085] This utility model further proposes a lithium-ion battery, including the electrode sheet described in the foregoing embodiments. The specific structure of the electrode sheet is the same as described in the above embodiments. Since the lithium-ion battery adopts all the technical solutions of all the above embodiments, it has at least all the technical effects brought about by the technical solutions of the above embodiments, which will not be repeated here. The electrode sheet can be made into a stacked cell or a wound cell. A stacked cell is a structure formed by stacking and compacting positive and negative electrode sheets and a separator layer by layer. This structure can provide a more uniform current distribution and good thermal management performance, making it suitable for high-capacity and high-energy-density applications. A wound cell is formed by winding the positive and negative electrode sheets and the separator together into a cylindrical or square structure. It has the characteristics of simple process and high production efficiency, making it very suitable for large-scale production and high-power output requirements. Since this lithium-ion battery adopts the electrode sheet solution in the foregoing embodiments, it also has the advantages of safety, low temperature, and long life.

[0086] In summary, the lithium-ion battery of this embodiment, by integrating the technologies in the foregoing embodiments, provides a lithium-ion battery design with excellent performance, stable structure, and ease of manufacture, which can achieve efficient, safe, and reliable battery performance in a variety of application scenarios.

[0087] The above description is only a part or preferred embodiment of this utility model. Neither the text nor the drawings should limit the scope of protection of this utility model. All equivalent structural transformations made using the content of this utility model specification and drawings under the overall concept of this utility model, or direct / indirect applications in other related technical fields, are included within the scope of protection of this utility model.

Claims

1. An electrode sheet, characterized in that, The electrode includes: A current collector, wherein at least one surface of the current collector has a connected tab welding area and a non-tab welding area; A safety coating is applied to at least one surface of the current collector, and the safety coating has a plurality of through holes. An active material layer is coated on the side of the safety coating facing away from the current collector, and at least a portion of the active material layer passes through the plurality of through holes and is connected to the current collector; The number of through holes near the tab welding area is greater than the number of through holes near the non-tab welding area.

2. The electrode sheet according to claim 1, characterized in that, The number of through holes gradually decreases from the tab welding area to the non-tab welding area.

3. The electrode sheet according to claim 1, characterized in that, The resistance of the safety coating is greater than that of the active material layer.

4. The electrode sheet according to claim 2, characterized in that, The volume of the active material layer within the plurality of through holes is less than or equal to the volume of the active material coated on the surface of the safety coating.

5. The electrode sheet according to claim 4, characterized in that, The inner diameter of the plurality of through holes is greater than 0.5 mm and less than 2 mm.

6. The electrode sheet according to claim 1 or 5, characterized in that, The multiple vias are formed on the security coating using a selective mask coating process or a laser processing process.

7. The electrode sheet according to claim 1, characterized in that, The sum of the projected areas of the plurality of through holes on the current collector is less than or equal to the surface area of ​​the safety coating.

8. The electrode sheet according to claim 1, characterized in that, The sum of the areas of the active material layer in contact with the current collector within the through hole is equal to the area of ​​the safety coating in contact with the current collector.

9. The electrode sheet according to claim 1, characterized in that, The shape of the plurality of through holes is at least one of circular, elliptical and polygonal.

10. A lithium-ion battery, characterized in that, Includes the electrode sheet as described in any one of claims 1 to 9.

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