Pole piece unit, battery cell, battery, mother sheet and preparation method
By using a gravure roller coating process to create a hollow area in the electrode unit, the problem of poor connection between the tab and the conductive sheet was solved, achieving stable connection and improved battery performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- EVE ENERGY CO LTD
- Filing Date
- 2026-05-26
- Publication Date
- 2026-07-03
Smart Images
Figure CN122337992A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of battery technology, specifically to electrode units, cells, batteries, master wafers, and preparation methods. Background Technology
[0002] The electrode includes a conductive substrate and a safety coating covering the conductive substrate, with an active material further disposed above the safety coating. Along the width direction of the conductive substrate, tab grooves are formed in the active material and safety coating using a laser or a scraper to connect the tabs to the conductive substrate.
[0003] Subsequently, the electrode sheet is cut along the length of the conductive substrate to divide it into electrode units of equal width. During the cutting process, because there is a certain gap between the groove wall of the tab groove and the cutting edge in the width direction of the conductive substrate, when the tab is connected to the electrode unit, the groove wall of the tab groove (composed of active material) supports one side of the tab, thereby increasing the overall thickness of the electrode sheet. For this reason, a punching mechanism is needed to punch the side of the tab groove near the cutting edge to form a punching notch so that the electrode sheet can protrude from the notch.
[0004] However, in related technologies, whether using a scraper or a laser, it is difficult to completely remove the active material from the tank walls. Residual active material adhering to the surface of the conductive sheet can lead to poor contact between the tabs and the conductive sheet, affecting conductivity. Summary of the Invention
[0005] This application provides electrode units, cells, batteries, master sheets, and preparation methods to solve or improve the problems of poor connection between the tabs and conductive sheets, and poor conductivity.
[0006] In a first aspect, this application provides an electrode unit, comprising: A conductive sheet has a length direction, a width direction and a thickness direction, and a tab connection area is provided on its surface, wherein the tab connection area extends through the conductive sheet along the width direction; A safety coating is applied to the surface of the conductive sheet. The safety coating has a hollow area, which corresponds to the tab connection area in the thickness direction. An active layer is disposed on the safety coating, and along the thickness direction, the projection of the active layer on the conductive sheet is located in the area outside the tab connection area.
[0007] In this embodiment, the conductive sheet has a tab connection area for connecting a positive or negative tab. A safety coating is applied to the surface of the conductive sheet using a gravure roller coating process. The surface of the gravure roller has grooves. As the gravure roller rolls on the conductive sheet, the area of the conductive sheet corresponding to the grooves along the thickness direction is not coated with the safety coating; this area is a cutout area. One end of the positive or negative tab can be located in the cutout area and directly connected to the surface of the conductive sheet, effectively avoiding interference from the safety coating on the connection of the positive or negative tab and ensuring connection reliability.
[0008] The tab connection area extends through the conductive sheet along its width. The active layer is disposed on the safety coating, and its projection onto the conductive sheet along the thickness direction lies outside the tab connection area, reserving a channel for subsequent connection of the positive or negative tab. No active layer is disposed within this channel; therefore, there is no need for additional punching of the active layer in this area, effectively avoiding the problem of active layer residue between the hollowed-out area and the conductive sheet, which could lead to poor connection and conductivity between the tab and the conductive sheet. This improves the connection stability between the positive or negative tab and the conductive sheet.
[0009] In one optional embodiment, the conductive sheet has a head end and a tail end arranged opposite to each other, the area of the region near the head end that is not coated with the active layer is S1, the area of the region near the tail end that is not coated with the active layer is S2, and the ratio of S1 to S2 is in the range of 3 to 5.
[0010] Beneficial effects: By controlling the ratio of the area of the unactive layer near the beginning and end of the electrode, asymmetrical conductivity and heat dissipation are achieved along the length of the electrode. This helps balance the difference in current density between the beginning and end of the electrode due to different electrode positions, avoiding local overcharging, over-discharging, or overheating, thereby improving the cycle life and safety of the battery cell.
[0011] In one optional embodiment, the conductive sheet includes a positive conductive sheet coated with a safety coating, the positive conductive sheet having a first end in the length direction, the length of the positive conductive sheet being L01, the distance between the edge of the tab connection area near the first end and the first end being L1, and the ratio of L1 / L01 ranging from 0.1% to 10%.
[0012] Beneficial effects: Placing the positive tab as close as possible to the end of the positive electrode conductive plate reduces the internal resistance at the end of the positive electrode conductive plate, thereby improving the battery's charge and discharge performance. Positioning the positive tab at the end of the positive electrode conductive plate facilitates rapid heat dissipation, improves the battery's heat dissipation conditions, and enhances the battery's safety and cycle stability in high-temperature environments.
[0013] In one optional embodiment, the conductive sheet includes a negative conductive sheet having a second end in the length direction, the length of the negative conductive sheet being L02, the distance between the edge of the tab connection area near the second end and the second end being L2, and the ratio of L2 / L02 being in the range of 30% to 70%.
[0014] Beneficial effects: The negative electrode tab can be positioned in the middle of the negative electrode conductive sheet along its length, i.e., a centrally located tab design. This balances the spatial distribution of current density on the negative electrode conductive sheet, ensuring that the electron transport path length from the tab to both ends of the negative electrode conductive sheet is approximately equal. The central placement of the negative electrode tab effectively prevents the risk of localized lithium plating, especially during high-rate charging. It ensures that the lithium intercalation reaction proceeds uniformly in all areas of the negative electrode conductive sheet, improving the battery's rate performance, safety, and cycle life.
[0015] In one optional embodiment, the conductive sheet is an aluminum foil, a copper foil, an aluminum foil composite conductive foil, or a copper foil composite conductive foil. And / or, the active layer is a positive electrode active layer or a negative electrode active layer.
[0016] Beneficial effects: Aluminum foil offers advantages such as high stability at high positive potentials, good conductivity, and light weight, and is commonly used as a positive electrode conductive sheet. Copper foil offers advantages such as high stability at low negative potentials, excellent conductivity, and high strength, and is commonly used as a negative electrode conductive sheet. Using both aluminum and copper foil ensures low electronic impedance, good mechanical support, and high compatibility with the active layer and safety coating of the conductive sheet.
[0017] In one optional embodiment, the conductive sheet includes a positive conductive sheet and a negative conductive sheet. Along the length direction, the length of the active layer on the positive conductive sheet is L10, and the length of the active layer on the negative conductive sheet is L20, with the ratio of L10 to L20 ranging from 0.7 to 0.9; the length of the positive conductive sheet is L01, and the length of the negative conductive sheet is L02, with the ratio of L01 to L02 ranging from 1 to 1.2.
[0018] Beneficial effects: For long positive conductive sheets, placing the positive tab near the end shortens the current transmission path and reduces ohmic polarization. In the winding process, the starting end of the positive conductive sheet is fixed, and the positive tab is positioned close to the starting end. Once winding begins, the positive tab is wound in, facilitating precise control and detection of the positive tab's position by automated equipment, ensuring the accuracy of the positive tab's position at the end of the cell after winding.
[0019] Secondly, this application also provides a battery cell, comprising: Positive electrode ear; A positive electrode conductive sheet has a thickness direction and a length direction. The surface of the positive electrode conductive sheet is coated with a safety coating. The safety coating has a hollow area in the thickness direction. The hollow area is connected to the positive electrode tab. Negative electrode ear; A negative electrode conductive sheet is disposed opposite to the positive electrode conductive sheet along the thickness direction, and the negative electrode conductive sheet is connected to the negative electrode tab.
[0020] Thirdly, this application also provides a battery, including electrode units or cells.
[0021] Fourthly, this application also provides a master sheet comprising a plurality of electrode units, wherein the plurality of electrode units are integrally formed along the width direction and the plurality of electrode units are integrally formed along the length direction.
[0022] Fifthly, this application also provides a preparation method for preparing electrode units, the preparation method comprising: Identify the tab connection area on the conductive substrate; A safety coating is applied to at least one side of a conductive substrate using a coating roller, the coating roller including a non-engraved area for reserving a cutout area in the coating surface of the safety coating; The active layer is coated on the safety coating, and along the thickness direction, the projection of the active layer is located in the area outside the tab connection area; The conductive substrate is cut to form electrode units.
[0023] In one alternative implementation, before determining the tab connection region on the conductive substrate, the method further includes: Position the conductive substrate on the worktable. Attached Figure Description
[0024] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0025] Figure 1 This is a schematic diagram of the structure of an electrode unit according to an embodiment of this application; Figure 2 This is a schematic diagram of the structure of the positive electrode conductive sheet, safety coating, positive electrode active material, hollow area and positive electrode tab in an electrode unit according to an embodiment of this application; Figure 3 This is a schematic diagram of the structure of the negative electrode conductive sheet, negative electrode active material, hollow area and negative electrode tab in an electrode unit according to an embodiment of this application; Figure 4 This is a schematic diagram of the structure of an electrode sheet according to an embodiment of this application; Figure 5 This is a schematic diagram of the structure of an electrode arrangement cutting positioning line and a cutting line according to an embodiment of this application; Figure 6 This is a schematic diagram of the structure of the conductive sheet, safety coating, and hollow area in an electrode sheet according to an embodiment of this application; Figure 7 This is a schematic flowchart of a preparation method according to an embodiment of this application; Figure 8 This is a schematic flowchart of another preparation method according to an embodiment of this application.
[0026] Explanation of reference numerals in the attached figures: 01. Conductive substrate; 1. Electrode unit; 101. Conductive sheet; 1011. Positive conductive sheet; 1012. First end; 1013. Negative conductive sheet; 1014. Second end; 1015. First end; 1016. Tail end; 2. Tab connection area; 3. Safety coating; 4. Hollowed-out area; 5. Active layer; 6. Cutting positioning line; 7. Positive active material; 8. Negative active material; 9. Positive tab; 10. Negative tab; 11. Cutting line; X, length direction; Y, width direction. Detailed Implementation
[0027] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0028] The electrode includes a conductive substrate and a safety coating covering the conductive substrate, with an active material further disposed above the safety coating. Along the width direction of the conductive substrate, tab grooves are formed in the active material and safety coating using a laser or a scraper to connect the tabs to the conductive substrate.
[0029] Subsequently, the electrode sheet is cut along the length of the conductive substrate to divide it into electrode units of equal width. During the cutting process, because there is a certain gap between the groove wall of the tab groove and the cutting edge in the width direction of the conductive substrate, when the tab is connected to the electrode unit, the groove wall of the tab groove (composed of active material) supports one side of the tab, thereby increasing the overall thickness of the electrode sheet. For this reason, a punching mechanism is needed to punch the side of the tab groove near the cutting edge to form a punching notch so that the electrode sheet can protrude from the notch.
[0030] However, in related technologies, whether using a scraper or a laser, it is difficult to completely remove the active material from the tank wall. Residual active material adhering to the surface of the conductive sheet can lead to poor contact between the tab and the conductive sheet, affecting conductivity. Therefore, this application provides an electrode unit, a cell, a battery, a master wafer, and a preparation method to solve or improve the problem of poor connection between the tab and the conductive sheet, and poor conductivity.
[0031] The following is combined Figures 1 to 8 This describes an embodiment of the present application.
[0032] According to embodiments of this application, in a first aspect, a master film is provided, with reference to... Figures 4 to 6 It includes multiple electrode units 1, which are integrally formed along the width direction Y and along the length direction X.
[0033] In some embodiments, reference Figures 4 to 5 The mother sheet has multiple tab connection areas 2, each tab connection area 2 extends along the width direction Y and penetrates the mother sheet, the multiple tab connection areas 2 are spaced apart along the length direction X, and an active layer 5 is provided between two adjacent tab connection areas 2.
[0034] In some embodiments, reference Figures 4 to 5 Each tab connection area 2 is provided with multiple hollow areas 4. The multiple hollow areas 4 located in the same tab connection area 2 are arranged at intervals along the width direction Y, and the hollow areas 4 in different tab connection areas 2 are arranged correspondingly along the length direction X.
[0035] In some embodiments, reference Figure 5 The mother sheet is cut along the cutting positioning line 6 and the cutting line 11 to form multiple electrode units 1. Each electrode unit has an electrode tab connection area 2, and each electrode tab connection area 2 is provided with a hollow area 4.
[0036] Specifically, first cut along the cutting positioning line 6, that is, cut along the length direction X, to form multiple long strip-shaped electrode units, and then cut along the cutting line 11, that is, cut along the width direction Y, to form electrode unit 1.
[0037] In some embodiments, a cutting tool (such as a cutter or laser) cuts along the cutting positioning line 6 to ensure that each of the electrode units formed after separation has a hollow area 4.
[0038] According to embodiments of this application, in a second aspect, a preparation method is also provided for preparing electrode unit 1, with reference to... Figure 6 and Figure 7 The preparation methods include: S102, Determine the tab connection area 2 on the conductive substrate 01.
[0039] Specifically, the camera device takes a picture of the conductive substrate 01 and transmits the picture of the conductive substrate 01 to the image analysis device. The image analysis device forms position information based on the preset size and position of the tab connection area 2 and transmits the position information to the infrared emitting device and the coating device. The infrared emitting device irradiates the conductive substrate 01 and marks the tab connection area 2.
[0040] S103. A safety coating 3 is applied to at least one side of a conductive substrate 01 using a coating roller. The coating roller includes a non-engraved area, which is used to reserve a cutout area 4 in the coating surface of the safety coating 3.
[0041] Specifically, the non-engraved area includes grooves, and the coating device drives the coating roller to move on the conductive substrate 01.
[0042] S104. The active layer 5 is coated on the safety coating 3, and the projection of the active layer 5 is located outside the tab connection area 2 along the thickness direction.
[0043] Specifically, the active layer 5 is coated onto the safety coating 3 to form the master film.
[0044] S105. The conductive substrate 01 is cut to form the electrode unit 1.
[0045] Specifically, the image analysis device forms position information based on the preset size of the electrode unit 1 and transmits the position information to the infrared emitting device and the cutting device. The infrared emitting device marks the cutting positioning line 6 and the cutting line 11 on the conductive substrate 01. The cutting device cuts the conductive substrate 01 along the cutting positioning line 6 and the cutting line 11 to form the electrode unit 1.
[0046] In this embodiment, a gravure roller is used to coat the safety coating 3 onto the conductive substrate 01. When the groove on the gravure roller corresponds to the conductive substrate 01, a hollow area 4 is formed in the area of the conductive substrate 01 corresponding to the groove. The active layer 5 is coated on the safety coating 3, and the tab connection area 2 is avoided. After the conductive substrate 01 is cut to form multiple electrode units 1, there is no active layer 5 in the direction of width Y, corresponding to the edge of the electrode unit 1. This provides a channel for the positive tab 9 or negative tab 10 to connect to the hollow area 4, eliminating the process step of punching the active layer 5 in related technologies.
[0047] It should be noted that the safety coating 3 is a ceramic coating, whose main material is inorganic ceramic particles (such as alumina or boehmite), combined with polymer binders such as polyvinylidene fluoride or styrene-butadiene rubber and conductive agents. After coating, it forms a dense thin film on the surface of the conductive sheet 101. The high hardness and heat resistance of the ceramic material can effectively prevent metal burrs from piercing the separator during the cutting or use of the conductive substrate 01, preventing internal short circuits. At the same time, when the battery is subjected to mechanical abuse such as needle punctures, it can effectively prevent the copper foil and aluminum foil from contacting each other, inhibiting the spread of thermal runaway. Furthermore, the safety coating 3 can also serve as a transition layer between the conductive substrate 01 and the active layer 5, enhancing the adhesion between the two and preventing the active material from peeling off during long-term cycling.
[0048] In some embodiments, reference Figure 8 Before dividing the surface of the conductive substrate 01 into the tab connection region 2, the method further includes: S101, Position the conductive substrate 01 on the worktable.
[0049] According to embodiments of this application, in a third aspect, an electrode unit 1 is provided, with reference to... Figure 1 The active layer includes a conductive sheet 101, a safety coating 3, and an active layer 5. Specifically, the conductive sheet 101 has a length direction X, a width direction Y, and a thickness direction, and its surface is provided with a tab connection area 2, which extends through the conductive sheet 101 along the width direction Y. The safety coating 3 is coated on the surface of the conductive sheet 101 and has a hollow area 4, which corresponds to the tab connection area 2 in the thickness direction. The active layer 5 is disposed on the safety coating 3, and along the thickness direction, the projection of the active layer 5 on the conductive sheet 101 is located in the area outside the tab connection area 2.
[0050] In this embodiment, the conductive sheet 101 is provided with a tab connection area 2 for connecting the positive tab 9 or the negative tab 10. A safety coating 3 is applied to the surface of the conductive sheet 101 using a gravure roller coating process. The surface of the gravure roller has grooves. When the gravure roller rolls on the conductive sheet 101, along the thickness direction, the area of the conductive sheet 101 corresponding to the groove is not coated with the safety coating 3; this area is the hollow area 4. One end of the positive tab 9 or the negative tab 10 can be located in the hollow area 4 and directly connected to the surface of the conductive sheet 101, effectively avoiding interference from the safety coating 3 on the connection of the positive tab 9 or the negative tab 10, and ensuring connection reliability.
[0051] The tab connection area 2 extends through the conductive sheet 101 along the width direction Y. The active layer 5 is disposed on the safety coating 3, and its projection on the conductive sheet 101 along the thickness direction is located outside the tab connection area 2, reserving a channel for the subsequent connection of the positive tab 9 or the negative tab 10. The active layer 5 is not disposed in the channel. Therefore, there is no need to perform additional punching of the active layer 5 in this area by a punching mechanism. This effectively avoids the problem of poor connection and poor conductivity of the positive tab 9 or the negative tab 10 with the conductive sheet 101 due to the presence of active layer 5 residue between the hollow area 4 and the conductive sheet 101, thus improving the connection stability between the positive tab 9 or the negative tab 10 and the conductive sheet 101.
[0052] In existing technology, after the master sheet is cut, there is a certain gap between the groove wall of the tab groove and the cutting edge in the width direction Y of the electrode unit 1. When the positive tab 9 or negative tab 10 is connected to the conductive sheet 101, the groove wall (composed of active material) of the tab groove supports one side of the positive tab 9 or negative tab 10, thereby increasing the overall thickness of the electrode unit 1. For this purpose, a punching mechanism is needed to punch the side of the tab groove near the cutting edge to form a punching notch so that the positive tab 9 or negative tab 10 can protrude from the notch. In the structure of this application, referring to Figure 1 Along the width direction Y, the edge of the tab connection area 2 of the electrode unit 1 has a notch for the positive tab 9 or the negative tab 10 to extend. Therefore, the punching notch process mentioned in the background art is eliminated, reducing equipment cost and process complexity.
[0053] In one embodiment, reference Figure 1 and Figure 2 The conductive sheet 101 has a head end 1015 and a tail end 1016 arranged opposite to each other. The area of the region near the head end 1015 that is not coated with the active layer 5 is S1, and the area of the region near the tail end 1016 that is not coated with the active layer 5 is S2. The ratio of S1 to S2 is in the range of 3 to 5.
[0054] In this embodiment, by controlling the ratio of the area of the area near the first end 1015 and the last end 1016 where the active layer 5 is not provided, an asymmetrical conductivity and heat dissipation capacity are formed in the length direction X. This helps to balance the difference in current density between the first and last ends 1016 caused by the different positions of the tabs, avoid local overcharging, over-discharging or overheating, thereby improving the cycle life and safety of the battery cell.
[0055] When the tab is connected to the end near the conductive sheet 101, the current path on the conductive sheet 101 is longer, resulting in a slightly higher internal resistance at the end of the conductive sheet 101 near the tab than at the end away from the tab. In the region of the conductive sheet 101 without the active layer 5, its resistivity is much lower than in the region coated with the active layer 5. Therefore, by designing the area of the blank region near the tab (S1) to be larger than the area of the blank region away from the tab (S2), such that the ratio of S1 / S2 is between 3 and 5, the high conductivity of the conductive sheet 101 itself can be used to compensate for the internal resistance in the length direction X.
[0056] In one embodiment, reference Figure 2 The conductive sheet 101 includes a positive conductive sheet 1011, which is coated with a safety coating 3. The positive conductive sheet 1011 has a first end 1012 in the length direction X. The length of the positive conductive sheet 1011 is L01. The distance between the edge of the tab connection area 2 on the positive conductive sheet 1011 near the first end 1012 and the first end 1012 is L1. The ratio of L1 / L01 is in the range of 0.1% to 10%.
[0057] In this embodiment, the positive tab 9 is positioned as close as possible to the end of the positive conductive plate 1011, reducing the internal resistance at the end of the positive conductive plate 1011 and thus improving the battery's charge and discharge performance. Positioning the positive tab 9 at the end of the positive conductive plate 1011 facilitates rapid heat dissipation, improves the battery's heat dissipation conditions, and enhances the battery's safety and cycle stability under high-temperature environments.
[0058] In one embodiment, reference Figure 3 The conductive sheet 101 includes a negative conductive sheet 1013, which has a second end 1014 in the length direction X. The length of the negative conductive sheet 1013 is L02. The distance between the edge of the tab connection area 2 on the negative conductive sheet 1013 near the second end 1014 and the second end 1014 is L2. The ratio of L2 / L02 is in the range of 30% to 70%.
[0059] In this embodiment, the negative electrode tab 10 can be arranged in the middle region along the length X of the negative electrode conductive sheet 1013, i.e., a centrally located tab design. This balances the spatial distribution of current density on the negative electrode conductive sheet 1013, making the electron transport path length from the negative electrode tab 10 to both ends of the negative electrode conductive sheet 1013 approximately equal. The central arrangement of the negative electrode tab 10 effectively prevents the risk of localized lithium plating, especially during high-rate charging, ensuring uniform lithium intercalation reaction in all areas of the negative electrode conductive sheet 1013, thus improving battery safety and cycle life.
[0060] When the negative electrode tab 10 is located in the middle region of the negative electrode conductive sheet 1013, the current flows from both ends of the negative electrode conductive sheet 1013 to the negative electrode tab 10 along approximately equal paths, resulting in a flatter potential distribution across the entire negative electrode conductive sheet 1013. During charging, the lithium intercalation potential in each region of the negative electrode conductive sheet 1013 tends to be consistent, solving the problem of lithium plating on the negative electrode under high-current charging conditions and improving battery safety.
[0061] In one embodiment, the conductive sheet 101 is an aluminum foil, a copper foil, an aluminum foil composite conductive foil, or a copper foil composite conductive foil; And / or, the active layer 5 is a positive electrode active layer or a negative electrode active layer.
[0062] In this embodiment, the positive electrode conductive sheet 1011 is an aluminum foil, and the positive electrode active layer 5 disposed on the aluminum foil is lithium iron phosphate; the negative electrode conductive sheet 1013 is a copper foil, and the negative electrode active layer 5 disposed on the copper foil is graphite.
[0063] Aluminum foil offers advantages such as high stability at high positive potentials, good conductivity, and light weight, and is typically used as the positive electrode conductive sheet 1011. Copper foil offers advantages such as high stability at low negative potentials, excellent conductivity, and high strength, and is typically used as the negative electrode conductive sheet 1013. The use of both aluminum and copper foil ensures that the conductive sheet 101 has low electronic impedance, good mechanical support, and high compatibility with the active layer 5 and the safety coating 3.
[0064] Specifically, the positive electrode active layer includes positive electrode active material 7, which is lithium iron phosphate. Lithium iron phosphate has high safety, long cycle life and low cost, and is suitable for power batteries (especially commercial vehicles and energy storage power stations) and energy storage fields. The negative electrode active layer includes negative electrode active material 8, which is graphite.
[0065] In some embodiments, aluminum foil composite conductive foil is typically a composite material of polyethylene terephthalate (PET) and aluminum foil; copper foil composite conductive foil is typically a composite material of polyethylene terephthalate (PET) and copper foil.
[0066] In one embodiment, reference Figure 2 and Figure 3 The conductive sheet 101 includes a positive conductive sheet 1011 and a negative conductive sheet 1013. Along the length direction X, the length of the active layer 5 on the positive conductive sheet 1011 is L10, and the length of the active layer 5 on the negative conductive sheet 1013 is L20. The ratio of L10 to L20 is in the range of 0.7 to 0.9. The length of the positive conductive sheet 1011 is L01, and the length of the negative conductive sheet 1013 is L02. The ratio of L01 to L02 is in the range of 1 to 1.2.
[0067] In this embodiment, for a relatively long positive electrode conductive sheet 1011, placing the positive electrode tab 9 near the end shortens the current transmission path on the positive electrode conductive sheet 1011 and reduces ohmic polarization. During the winding process, the starting end of the positive electrode conductive sheet 1011 is fixed, and the positive electrode tab 9 is positioned near the starting end. After winding begins, the positive electrode tab 9 is wound in, which facilitates precise control and detection of the position of the positive electrode tab 9 by automated equipment, ensuring the accuracy of the positive electrode tab 9's position at the end of the cell after winding.
[0068] It is important to explain that ohmic polarization is a phenomenon that occurs during the charging and discharging process of a battery, caused by the need for current to overcome the inherent ohmic internal resistance as it passes through the various components. Specifically, it manifests as a momentary decrease or increase in the battery's operating voltage relative to its equilibrium voltage. Essentially, it follows Ohm's law, where the voltage drop equals the product of the operating current and the total internal resistance of the battery. This internal resistance is not from a single source but encompasses the intrinsic ionic resistance of the electrode materials and electrolyte, the electronic resistance of electrons conducting in the conductive sheet 101 and the active layer 5, and the contact resistance between components due to poor contact or interface effects. A significant characteristic of ohmic polarization is its extremely rapid response, occurring almost simultaneously with the application or interruption of current. It is primarily related to the magnitude of the instantaneous current and the ambient temperature; high current or low-temperature environments that reduce electrolyte conductivity exacerbate this polarization phenomenon. In practical applications, ohmic polarization not only directly reduces the battery's available energy and power output, but the Joule heat it generates can also cause the battery temperature to rise. If the internal resistance is too high or the heat dissipation is poor, it may even become a cause of thermal runaway. Therefore, reducing the battery's internal resistance is one of the core objectives for optimizing battery performance and safety.
[0069] In some embodiments, the thickness of the safety coating 3 is between 0.1 μm and 10 μm. If the thickness is less than 0.1 μm, the uniformity of the safety coating 3's coverage is difficult to guarantee, resulting in a reduced heat insulation effect and inability to provide effective safety protection. If the thickness is greater than 10 μm, although the safety may be higher, it increases the overall thickness of the electrode, occupies the limited space inside the battery, and makes winding difficult. At the same time, it also increases the resistance to lithium-ion migration and reduces battery power.
[0070] According to an embodiment of this application, in a fourth aspect, this application also provides a battery cell, including a positive electrode tab 9, a positive conductive sheet 1011, a negative electrode tab 10, and a negative conductive sheet 1013. Specifically, the positive conductive sheet 1011 has a thickness direction and a length direction X. The surface of the positive conductive sheet 1011 is coated with a safety coating 3. The safety coating 3 has a hollow area 4 in the thickness direction. The hollow area 4 is located near the end of the positive conductive sheet 1011, and the hollow area 4 is connected to the positive electrode tab 9. The negative conductive sheet 1013 is disposed opposite to the positive conductive sheet 1011 along the thickness direction. The negative conductive sheet 1013 is connected to the negative electrode tab 10, and the negative electrode tab 10 is located at the middle position of the negative conductive sheet 1013 along the length direction X.
[0071] According to an embodiment of this application, in a fifth aspect, this application also provides a battery, including an electrode unit 1 or a cell.
[0072] The master wafer includes the positive electrode master wafer. Two examples are given below, combining... Figures 1 to 8 The above plan will be explained.
[0073] Example 1 refer to Figure 5 A positive electrode substrate includes a positive electrode conductive substrate, a safety coating 3, and a positive electrode active layer 5. The positive electrode conductive substrate is made of aluminum foil with a thickness of 15 μm, a length L of 2000 mm, and a width W of 300 mm. Two tab connection areas 2 are pre-set on its surface. The two tab connection areas 2 penetrate the aluminum foil along the width direction Y and are equally spaced along the length direction X with a spacing of 900 mm.
[0074] The safety coating 3 is applied by gravure roller coating, which coats the aluminum foil with a ceramic coating (mainly composed of alumina and PVDF binder) on both sides. The coating thickness is 3μm. The safety coating 3 has four hollow areas 4 at the positions corresponding to each tab connection area 2, so that the positive conductive substrate corresponding to the hollow area 4 can be directly connected to the positive tab 9. The four hollow areas 4 are arranged at intervals along the width direction Y.
[0075] A positive electrode active layer 5 (a mixture of lithium cobalt oxide, conductive carbon black and PVDF) is coated on the safety coating 3. The coating thickness is 80 μm. The positive electrode active layer 5 completely covers the safety coating 3, but does not cover the tab connection area 2.
[0076] Example 2 Method for preparing positive electrode unit: S101. Position the positive conductive substrate on the worktable.
[0077] S102. Determine the tab connection area 2 on the positive conductive substrate.
[0078] Specifically, the camera device takes a picture of the positive conductive substrate and transmits the picture of the positive conductive substrate to the image analysis device. The image analysis device forms position information based on the preset size and position of the tab connection area 2 and transmits the position information to the infrared emitting device and the coating device. The infrared emitting device irradiates the positive conductive substrate and marks the tab connection area 2.
[0079] S103. A safety coating 3 is applied to at least one side of the positive conductive substrate using a coating roller. The coating roller includes a non-engraved area, which is used to reserve a cutout area 4 in the coating surface of the safety coating 3.
[0080] Specifically, the non-engraved area includes grooves, and the coating device drives the coating roller to move on the positive conductive substrate.
[0081] S104. The active layer 5 is coated on the safety coating 3, and the projection of the active layer 5 is located outside the tab connection area 2 along the thickness direction.
[0082] Specifically, the active layer 5 is coated onto the safety coating 3 to form the positive electrode master sheet.
[0083] S105. Cut the positive conductive substrate to form the positive electrode unit 1.
[0084] Although embodiments of this application have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of this application, and such modifications and variations all fall within the scope defined by the appended application.
[0085] Furthermore, in the description of this application, the term "comprising" means "including but not limited to". The terms "second", "first", "second", etc., are used merely as illustrative purposes and do not impose numerical requirements or establish an order.
[0086] In this application, unless otherwise expressly specified and limited, "above" or "below" the first feature can mean that the second and first features are in direct contact, or that they are in indirect contact through an intermediate medium. Furthermore, "above," "on top of," and "over" the first feature can mean that the second feature is directly above or diagonally above the first feature, or simply indicates that the second feature is at a higher horizontal level than the first feature. "Below," "below," and "under" the first feature can mean that the second feature is directly below or diagonally below the first feature, or simply indicates that the second feature is at a lower horizontal level than the first feature.
[0087] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.
[0088] Furthermore, the terms "second" and "first" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "second" or "first" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.
[0089] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application 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, and therefore should not be construed as a limitation of this application.
Claims
1. A pole piece unit characterized by, include: The conductive sheet (101) has a length direction (X), a width direction (Y) and a thickness direction, and its surface is provided with a tab connection area (2), which penetrates the conductive sheet (101) along the width direction (Y). A safety coating (3) is applied to the surface of the conductive sheet (101). The safety coating (3) has a hollow area (4) which corresponds to the tab connection area (2) in the thickness direction. An active layer (5) is disposed on the safety coating (3), and along the thickness direction, the projection of the active layer (5) on the conductive sheet (101) is located in the area outside the tab connection area (2).
2. The pole piece unit of claim 1, wherein The conductive sheet (101) has a head end (1015) and a tail end (1016) arranged opposite to each other. The area of the region near the head end (1015) and not coated with the active layer (5) is S1, and the area of the region near the tail end (1016) and not coated with the active layer (5) is S2. The ratio of S1 to S2 is in the range of 3 to 5.
3. The pole piece unit according to any one of claims 1 to 2, characterized in that, The conductive sheet (101) includes a positive conductive sheet (1011), the positive conductive sheet (1011) is coated with a safety coating (3), the positive conductive sheet (1011) has a first end (1012) in the length direction (X), the length of the positive conductive sheet (1011) is L01, the distance between the edge of the tab connection area (2) near the first end (1012) and the first end (1012) is L1, and the ratio of L1 / L01 is in the range of 0.1% to 10%.
4. The pole piece unit according to any one of claims 1 to 2, characterized in that, The conductive sheet (101) includes a negative conductive sheet (1013), the negative conductive sheet (1013) has a second end (1014) in the length direction (X), the length of the negative conductive sheet (1013) is L02, the distance between the edge of the tab connection area (2) near the second end (1014) and the second end (1014) is L2, and the ratio of L2 / L02 is in the range of 30% to 70%.
5. The pole piece unit according to any one of claims 1 to 2, characterized in that, The conductive sheet (101) is an aluminum foil, a copper foil, an aluminum foil composite conductive foil, or a copper foil composite conductive foil. And / or, the active layer (5) is a positive active layer or a negative active layer.
6. The electrode unit according to any one of claims 1 to 2, characterized in that, The conductive sheet (101) includes a positive conductive sheet (1011) and a negative conductive sheet (1013). Along the length direction (X), the length of the active layer (5) on the positive conductive sheet (1011) is L10, and the length of the active layer (5) on the negative conductive sheet (1013) is L20. The ratio of L10 to L20 is in the range of 0.7 to 0.
9. The length of the positive conductive sheet (1011) is L01, and the length of the negative conductive sheet (1013) is L02. The ratio of L01 to L02 is in the range of 1 to 1.
2.
7. A battery cell, characterized in that, include: Positive electrode ear (9); A positive electrode conductive sheet (1011) has a thickness direction and a length direction (X). The surface of the positive electrode conductive sheet (1011) is coated with a safety coating (3). The safety coating (3) has a hollow area (4) in the thickness direction. The hollow area (4) is connected to the positive electrode tab (9). Negative electrode ear (10); A negative electrode conductive sheet (1013) is disposed opposite to the positive electrode conductive sheet (1011) along the thickness direction, and the negative electrode conductive sheet (1013) is connected to the negative electrode tab (10).
8. A battery, characterized by Includes the electrode unit (1) as described in any one of claims 1 to 6 or the cell as described in claim 7.
9. A master slice, characterized by It includes multiple electrode units (1) as described in any one of claims 1 to 6, wherein the multiple electrode units (1) are integrally formed along the width direction (Y) and the multiple electrode units (1) are integrally formed along the length direction (X).
10. A method of manufacture, characterized by, The method for preparing the electrode unit (1) according to any one of claims 1 to 6 comprises: Identify the tab connection area on the conductive substrate; A safety coating is applied to at least one side of a conductive substrate using a coating roller, the coating roller including a non-engraved area for reserving a cutout area in the coating surface of the safety coating; The active layer is coated on the safety coating, and along the thickness direction, the projection of the active layer is located in the area outside the tab connection area; The conductive substrate is cut to form electrode units.
11. The preparation method according to claim 10, characterized in that, Before determining the tab connection area on the conductive substrate, the method further includes: Position the conductive substrate on the worktable.