Positive current collector, polar band and battery

Abstract

The utility model discloses an anode current collector, a polar band and a battery, the anode current collector comprises a base body and a conducting layer, and the surface of the base body is provided with a coating area used for coating anode coating; the conductive layer is embedded in the base body, the projection of the conductive layer on the surface of the base body forms a projection area in the direction perpendicular to the surface of the base body, the projection area coincides with the coating area and is located at the outline edge position of the coating area, and the conductivity of the conductive layer is lower than that of the anode coating. According to the positive current collector, by reducing the conduction performance of the conductive ions at the contour edge position of the coating area, the conductive ions can have sufficient time to be deintercalated, the conductive ions are prevented from being accumulated and separated out at the contour edge position of the coating area, and the cycle life is prolonged. The carrier is applied to the field of carriers of energy storage elements.

Description

Technical Field

[0001] The utility model relates to the field of carriers of energy storage elements, in particular to a positive electrode current collector, a pole belt and a battery. Background Art

[0002] Lithium-ion batteries have the advantages of high energy density and power density, high operating voltage, light weight, small size, long cycle life, good safety, and green environmental protection. Lithium-ion batteries have broad application prospects in portable appliances, power tools, large energy storage, and electric transportation power sources.

[0003] In the related technology, due to the kinetic differences between the positive and negative electrodes of lithium-ion batteries, lithium deposition is very likely to occur at the head and tail of the anode during long-term room temperature charge and discharge cycles of lithium-ion batteries. Especially in the later stages of the cycle, as the electrolyte is consumed, lithium deposition at the head and tail of the negative electrode is more serious, the battery cell expands significantly, and the cycle attenuation is obvious, which seriously affects the long-term cycle stability of the lithium battery. Utility Model Content

[0004] The utility model aims to solve at least one of the technical problems existing in the prior art. To this end, the utility model provides a positive electrode current collector that can reduce edge lithium deposition and increase cycle life.

[0005] A pole strip forming the positive electrode current collector is also proposed.

[0006] A battery having the positive electrode current collector is also provided.

[0007] According to the first embodiment of the present invention, the positive electrode current collector includes:

[0008] A substrate having a coating area on its surface for coating positive electrode coating;

[0009] A conductive layer is embedded in the substrate. Along a direction perpendicular to the surface of the substrate, the projection of the conductive layer on the surface of the substrate forms a projection area. The projection area overlaps with the coating area and is located at the edge of the contour of the coating area. The conductivity of the conductive layer is lower than the conductivity of the positive electrode coating.

[0010] The positive electrode current collector according to the first embodiment of the utility model has at least the following beneficial effects:

[0011] 1. The conductive layer is arranged at the edge of the coating area. Because the conductivity of the conductive layer is lower than that of the positive electrode coating in the coating area, the conduction rate of the conductive ions at the edge of the coating area is reduced, so the lithium ions have sufficient time to deintercalate. When forming a battery cell, the positive electrode sheet and the negative electrode sheet need to be stacked and aligned with each other. The positive electrode coating at the edge of the positive electrode sheet is affected by the conductive layer. The conductive ions in this part of the positive electrode coating will be deintercalated into the negative electrode coating at the edge of the negative electrode sheet at a lower rate. The deintercalation rate of the conductive ions is reduced, making it difficult for the conductive ions to accumulate and precipitate on the surface of the negative electrode sheet, thereby improving the cycle life.

[0012] 2. The conductive layer is embedded in the substrate, which reduces the electron conduction rate in the substrate, thereby reducing the deintercalation rate of lithium ions in the positive electrode coating. The volume of the positive electrode coating in the coating area on the substrate surface will not be affected by the volume of the conductive layer. The positive electrode coating on the substrate surface can be coated with a normal volume, so that the energy provided by the positive electrode coating can remain unchanged. Under the premise that the battery's energy storage performance remains unchanged, the battery's cycle life is further improved.

[0013] According to some embodiments of the present invention, the positive electrode current collector is used for winding a battery cell, the coating area has two width sides in the same direction as the width direction of the substrate, and the projection area is located at a contour edge position corresponding to at least one of the two width sides of the coating area.

[0014] According to some embodiments of the present invention, the length of the projection area along the length direction of the substrate is 2 mm to 10 mm.

[0015] According to some embodiments of the present invention, the length of the projection area along the width direction of the substrate is d, the length of the coating area along the width direction of the substrate is D, and the positive electrode current collector satisfies: 0.2D≤d≤0.5D.

[0016] According to some embodiments of the present invention, along the width direction of the substrate, the projection area is located in the middle of the coating area.

[0017] According to some embodiments of the present invention, the projection area is located at the contour edge positions corresponding to the two width sides of the coating area.

[0018] According to some embodiments of the present invention, the substrate includes a first layer and a second layer that overlap, and the conductive layer is located between the first layer and the second layer.

[0019] According to some embodiments of the present invention, the positive electrode current collector is used in a laminated battery cell.

[0020] The pole band according to the second embodiment of the utility model includes:

[0021] A base tape is embedded with a plurality of conductive areas, wherein the plurality of conductive areas are sequentially spaced apart along the length direction of the base tape, and the conductive area has a cutting position in the middle along the length direction of the base tape. The base tape is cut at the cutting position to form the positive electrode current collector described in the embodiment of the first aspect of the utility model, and the conductive area is cut to form the conductive layer.

[0022] The pole strip according to the embodiment of the second aspect of the utility model has at least the following beneficial effects: a plurality of pole strips are formed by cutting the pole strip, and each cutting can separate a complete positive electrode current collector, which is more convenient to use.

[0023] A battery according to a third aspect of the present invention includes:

[0024] A positive electrode sheet, comprising the positive electrode current collector described in the embodiment of the first aspect of the utility model and a positive electrode coating coated on the surface of the positive electrode current collector.

[0025] The battery according to the embodiment of the third aspect of the utility model has at least the following beneficial effects: through the conductive layer of the positive electrode current collector in the embodiment of the first aspect, the conduction rate of lithium ions in the positive electrode coating is reduced, so that the lithium ions at the edge of the coating area contour have sufficient time to deintercalate, so as to avoid lithium precipitation at the edge of the coating area contour, thereby improving the cycle and safety performance of the battery.

[0026] Additional aspects and advantages of the present invention will be given in part in the following description, and in part will become apparent from the following description, or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention is further described below with reference to the accompanying drawings and embodiments, wherein:

[0028] Figure 1 A schematic top view of a positive electrode current collector according to an embodiment of the utility model;

[0029] Figure 2 A schematic side view of a positive electrode current collector having a positive electrode coating according to an embodiment of the utility model;

[0030] Figure 3 It is a top view schematic diagram of a polar band according to an embodiment of the utility model.

[0031] Figure Number:

[0032] Substrate 100; coating area 110; first layer 120; second layer 130;

[0033] Conductive layer 200 ; projection area 210 . DETAILED DESCRIPTION

[0034] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0035] In the description of the present invention, it should be understood that the descriptions involving orientation, such as the orientation or positional relationship indicated as up, down, etc., are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0036] In the description of the present utility model, "several" refers to one or more, and "multiple" refers to two or more. If there is a description of "first" or "second", 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 the indicated technical features or implicitly indicating the order of the indicated technical features.

[0037] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0038] In the related art, after a certain number of charge and discharge cycles of lithium-ion batteries, the electrolyte inside the battery is consumed, resulting in the edge of the battery cell inside the battery, which is prone to lithium deposition. Taking a wound battery cell as an example, after the wound battery cell is disassembled, it can be divided into a positive electrode sheet, a diaphragm, a negative electrode sheet and a diaphragm. The lithium deposition position generally occurs at the head and tail ends of the negative electrode sheet along the length direction; taking a laminated battery cell as an example, after the laminated battery is disassembled, it can also be divided into a positive electrode sheet, a diaphragm, a negative electrode sheet and a diaphragm. The lithium deposition position generally occurs at the contour edge of the negative electrode sheet. It can be seen that the contour edge of the negative electrode sheet is more prone to lithium deposition, and when lithium deposition occurs on the negative electrode sheet, the volume of the negative electrode will increase, the battery cell will further expand, causing the battery cycle to be significantly attenuated and the cycle life to be reduced; even when the lithium dendrites deposited from the negative electrode pierce the diaphragm to contact the positive electrode sheet, it will cause a short circuit inside the battery, and there is a risk of loss of control.

[0039] Reference Figure 1 and Figure 2As shown, the first embodiment of the utility model proposes a positive electrode current collector, including: a substrate 100 and a conductive layer 200, the surface of the substrate 100 has a coating area 110 for coating a positive electrode coating; the conductive layer 200 is embedded in the substrate 100, and along the direction perpendicular to the surface of the substrate 100, the projection of the conductive layer 200 on the surface of the substrate 100 forms a projection area 210, the projection area 210 overlaps with the coating area 110, and is located at the edge of the contour of the coating area 110, the conductivity of the conductive layer 200 is lower than the conductivity of the positive electrode coating, and the positive electrode current collector reduces the conductive ions at the edge of the contour of the coating area 110. The conductive performance allows the conductive ions to have sufficient time to be deintercalated, thereby avoiding the conductive ions from accumulating and precipitating at the edge of the contour of the coating area 110 and improving the cycle life.

[0040] In this embodiment, the substrate 100 is generally a foil material, the substrate 100 of the positive electrode current collector is generally an aluminum foil or an aluminum alloy foil material, and the positive electrode coating applied on the surface of the substrate 100 is generally an active material with lithium ions or sodium ions, such as ternary nickel cobalt manganese oxide, lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, nickel cobalt aluminum oxide; it can also be a transition metal oxide, Prussian blue / white compound, polyanion compound. Among them, the two opposite surfaces of the substrate 100 are fully coated with positive electrode coating, that is, the two opposite surfaces of the substrate 100 are coating areas 110, so as to make full use of the space in the battery.

[0041] The conductive layer 200 is an inorganic material, and the inorganic material is one or more of boehmite, aluminum oxide, magnesium oxide, magnesium hydroxide, silicon oxide, etc. The conductivity of the inorganic material is low, so that although the conductive layer 200 can conduct electricity, the rate of conducting electrons is low. When the electrons pass through, they can only be transported at a lower rate, which increases the transportation time of the electrons. When the conductive layer 200 is embedded in the substrate 100, the conductive layer 200 will reduce the rate at which the electrons in the substrate 100 are conducted to the coating area 110, so that the rate at which the conductive ions in the positive electrode coating in the coating area 110 are excited by the electrons is reduced, and the conductive ions need to spend more time to complete the deintercalation, which effectively avoids the conductive ions from being accumulated and precipitated on the surface of the negative electrode sheet due to the excessively fast deintercalation rate. Moreover, because the conductive layer 200 is embedded in the substrate 100, the volume of the positive electrode coating in the coating area 100 on the surface of the substrate 100 will not be affected by the volume of the conductive layer 200, and the positive electrode coating on the surface of the substrate 100 can be coated with a normal volume, so that the energy provided by the positive electrode coating can remain unchanged. Under the premise that the energy storage performance of the battery remains unchanged, the cycle life of the battery is further improved. In addition, when the density of the conductive layer 200 is lower than the density of the substrate 100, for example, when the inorganic material is silicon oxide, the conductive layer 200 is embedded in the substrate 100 and occupies part of the volume of the substrate 100. In theory, the weight of the positive electrode collector with the conductive layer 200 is lower than the weight of the positive electrode collector composed entirely of the substrate 100; the positive electrode coating remains unchanged, the weight of the positive electrode collector is reduced, so that the energy density of the positive electrode sheet is increased, and the energy density of the battery as a whole is increased.

[0042] Further, along the direction perpendicular to the surface of the substrate 100, the projection of the conductive layer 200 on the surface of the substrate 100 forms a projection area 210, and the projection area 210 overlaps with the coating area 110 and is located at the edge of the contour of the coating area 110. When forming a battery cell, the positive electrode sheet and the negative electrode sheet need to be stacked and aligned with each other. The negative electrode sheet generally undergoes lithium precipitation at the edge of the contour. Therefore, when the projection area 210 is located at the edge of the contour of the coating area 110, the conductive layer 200 will reduce the rate at which the conductive ions in the positive electrode sheet are embedded into the negative electrode sheet at the edge of the contour of the coating area 110, and the conduction rate of the conductive ions at the edge of the contour of the negative electrode sheet is reduced, so the conductive ions have sufficient time to deintercalate, avoiding the accumulation of conductive ions on the surface of the negative electrode sheet, thereby reducing the possibility of conductive ions being precipitated at the edge of the contour of the negative electrode sheet, and improving the cycle life of the battery. Among them, the conductive ions can be lithium ions or sodium ions.

[0043] Reference Figure 1 and Figure 2 As shown, in some specific embodiments of the present invention, the positive electrode current collector is used for winding the battery cell, the coating area 110 has two width sides in the same direction as the width direction of the substrate 100, and the projection area 210 is located at the contour edge position corresponding to at least one of the two width sides of the coating area 110.

[0044] It should be noted that a wound battery cell refers to a stacked body formed by stacking a positive electrode sheet, a separator, a negative electrode sheet and a separator, and then winding the stacked body with one wide side of the stack as the winding axis to form a wound body, which is the wound battery cell.

[0045] It is worth understanding that after the wound cell is disassembled, the lithium deposition position generally occurs at the head end and tail end of the negative electrode sheet along the length direction. Therefore, the projection area 210 is set at the contour edge position corresponding to at least one of the width sides of the coating area 110. When the positive electrode sheet and the negative electrode sheet are stacked to form a laminate, and the laminate is wound to form a winding body, the two width sides of the positive electrode sheet are respectively aligned with the head end and tail end of the negative electrode sheet along the length direction. When the projection area 210 of the positive electrode sheet is set at at least one of the two width sides, the conductive layer 200 can reduce the conductivity of lithium ions at the head end and / or tail end of the negative electrode sheet along the length direction, thereby improving the lithium deposition of the negative electrode sheet and improving the cycle performance of the negative electrode sheet.

[0046] In this embodiment, the projection area 210 is located at the contour edge position corresponding to the two width sides of the coating area 110, so that the conductive layer 200 can reduce the conductivity of lithium ions at the head and tail ends of the negative electrode sheet along the length direction, thereby improving the lithium deposition of the negative electrode sheet and improving the cycle performance of the negative electrode sheet.

[0047] Reference Figure 1 and Figure 2 As shown, in some specific embodiments of the present invention, the length of the projection area 210 along the length direction of the substrate 100 is 2 mm to 10 mm.

[0048] It is worth understanding that by making the projection area 210 have a length along the length direction of the substrate 100, the lithium plating of the negative electrode sheet can be reduced within the region where the conductive layer 200 is located, while not excessively affecting the conductive properties of the current collector. That is, while increasing the battery cycle and safety performance, it does not affect the battery's performance, and has a higher cost-effectiveness.

[0049] In this embodiment, the length of the projection area 210 along the length direction of the substrate 100 is 2 mm to 10 mm, and the specific value can be selected according to actual needs.

[0050] Reference Figure 1 and Figure 2 As shown, in some specific embodiments of the present invention, the length of the projection area 210 along the width direction of the substrate 100 is d, the length of the coating area 110 along the width direction of the substrate 100 is D, and the positive electrode current collector satisfies: 0.2D≤d≤0.5D.

[0051] It is worth understanding that along the width direction of the substrate 100, the overall width of the projection area 210 accounts for 20% to 50% of the overall width of the coating area 110. When the charge moves along the length direction of the substrate 100, the conductive layer 200 and the substrate 100 together constitute a cross-section in the width direction of the current collector, and the area occupied by the cross-section of the conductive layer 200 does not exceed the area occupied by the cross-section of the substrate 100. Even if the conductive layer 200 reduces the transport speed of some charges, the rest of the substrate 100 can still smoothly transport charges, so that the conductive layer 200 has a smaller impact on the conductivity of the substrate 100.

[0052] Reference Figure 1 and Figure 2 As shown, in some specific embodiments of the present invention, along the width direction of the substrate 100 , the projection area 210 is located in the middle of the coating area 110 .

[0053] It is worth understanding that the projection area 210 is located in the middle of the coating area 110. On the cross-section of the width direction of the current collector formed by the conductive layer 200 and the substrate 100, both sides of the conductive layer 200 have a substrate 100 with good conductivity. The conductive layer 200 can divert charges from both sides to the cross-section of the substrate 100 to avoid the charge accumulation in the area where the conductive layer 200 is located, thereby reducing the influence of the conductive layer 200 on the conductivity of the substrate 100.

[0054] As another embodiment, the positive electrode current collector can also satisfy: d=D, the projection area 210 will overlap with the coating area 110 along the width direction of the substrate 100, and the conductive layer 200 reduces the overall conductivity of the contour edge position corresponding to the width side of the substrate 100, making the contour edge position corresponding to the width side of the substrate 100 less likely to undergo lithium deposition.

[0055] Reference Figure 2 As shown, in some specific embodiments of the present invention, the substrate 100 includes a first layer 120 and a second layer 130 that overlap, and the conductive layer 200 is located between the first layer 120 and the second layer 130 .

[0056] It should be noted that the substrate 100 is formed by rolling a ductile foil material. The thickness of the substrate 100 after rolling is low, and it is difficult to directly embed the conductive layer 200 on the very thin substrate 100. Therefore, in this embodiment, the substrate 100 is formed by the first layer 120 and the second layer 130, and the conductive layer 200 is directly sandwiched between the first layer 120 and the second layer 130, and then the substrate 100 is rolled into one body, so that the conductive layer 200 is embedded in the substrate 100, and the manufacturing difficulty of the conductive layer 200 is reduced, and the manufacturing is more convenient. The first layer 120 and the second layer 130 can be formed into one body after rolling, and the use is reliable.

[0057] In some specific embodiments of the present invention, the positive electrode current collector is used in a laminated battery cell.

[0058] It should be noted that a laminated battery cell refers to a battery cell structure in which a plurality of positive electrode sheets and negative electrode sheets are alternately stacked, and a separator is provided between adjacent positive electrode sheets and negative electrode sheets along the stacking direction.

[0059] In this embodiment, the positive electrode collector is used for the laminated battery cell, and the laminated battery cell is in the shape of a rectangle, so that the positive electrode collector is in the shape of a rectangle, and the surface of the positive electrode collector perpendicular to the thickness direction is rectangular, the coating area 110 on the surface of the positive electrode collector will also be rectangular, and the projection area 210 of the conductive layer 200 on the surface of the positive electrode collector will be located in the coating area 110 and correspond to the contour edge position of the four sides of the coating area 110, thereby reducing the conductivity of lithium ions at the contour edge position of the coating area 110 to avoid lithium deposition at the edge position of the positive electrode collector.

[0060] Reference Figure 3 As shown, the second embodiment of the utility model proposes a pole strip, including: a base strip, a plurality of conductive areas are embedded in the base strip, the plurality of conductive areas are sequentially spaced apart along the length direction of the base strip, the conductive area has a cutting position in the middle along the length direction of the base strip, the base strip is cut at the cutting position to form the positive electrode current collector of the first embodiment of the utility model, and the conductive area is cut to form a conductive layer 200.

[0061] It is worth understanding that by cutting the pole strips to form multiple pole strips, each cutting can separate a complete positive electrode current collector, which is more convenient to use. The conductive area can be cut once to form a conductive layer 200 of a positive electrode current collector and another conductive layer 200 of another positive electrode current collector, respectively, and the cutting of the positive electrode current collector is more convenient. In addition, the two conductive areas can be directly formed by coating the conductive area once, without the need for each conductive layer 200 to be coated separately, and the production of the conductive layer 200 is more convenient and the production efficiency is higher.

[0062] In this embodiment, the length of the conductive area along the length direction of the baseband is the sum of the lengths of the two conductive layers 200 along the length direction of the substrate 100, that is, the length of the conductive area along the length direction of the baseband is a, and the length of the conductive layer 200 along the length direction of the substrate 100 is b. The pole band satisfies: a=2*b, and the cutting position will be located at the midline position of the conductive area along the length direction of the baseband. In the actual production process, it is inevitable that there are certain errors, so the conductive area also includes a margin area, the margin area is located between the two conductive layers 200, and the cutting position is located in the margin area to ensure that the length of the two conductive layers 200 can meet the use requirements. In this embodiment, the length of the margin area along the length direction of the baseband is 4mm, so the pole band satisfies: a=2*b+4.

[0063] The third embodiment of the utility model provides a battery, including: a positive electrode sheet, the positive electrode sheet includes the positive electrode collector of the first embodiment of the utility model and a positive electrode coating coated on the surface of the positive electrode collector.

[0064] Specifically, the battery includes a shell and a battery cell arranged in the shell, the battery cell includes a positive electrode sheet, a negative electrode sheet and a separator, the separator is used to separate the positive electrode sheet and the negative electrode sheet, and the positive electrode sheet includes the positive electrode collector of the first aspect of the utility model and the positive electrode coating coated on the surface of the positive electrode collector. Among them, the battery cell can be a wound battery cell or a laminated battery cell, and the shell will be adapted to the shape of the battery cell. In this embodiment, the battery is a cylindrical battery, the shell is cylindrical, and the battery cell is a wound battery cell, which is wound into a cylindrical shape to be inserted into the shell.

[0065] It is worth understanding that, through the conductive layer 200 of the positive electrode current collector in the first aspect of the embodiment, the conduction rate of lithium ions in the positive electrode coating is reduced, so that the lithium ions at the edge of the contour of the coating area 110 have sufficient time to deintercalate, so as to avoid lithium precipitation at the edge of the contour of the coating area 110, thereby improving the cycle and safety performance of the battery.

[0066] For ease of understanding, the following specific embodiment is used to illustrate the solution in this embodiment. It should be noted that the following is only an exemplary description and does not constitute a specific limitation on the present utility model:

[0067] The distance along the length direction of the substrate 100 is the length, and the distance along the width direction of the substrate 100 is the width. The positive electrode coating covers the surface of the positive electrode collector. The width of the positive electrode collector is 8u. The width of the projection area 210 formed by the conductive layer 200 is 0u / 2u / 3u / 4u respectively. The overlapping length of the head end of the negative electrode sheet and the projection area 210 formed by the conductive layer 200 in the positive electrode sheet is 4mm. The overlapping length of the tail end of the negative electrode sheet and the projection area 210 formed by the conductive layer 200 in the positive electrode sheet is 4mm. The battery cell is made for testing and comparison. The specific scheme is as follows:

[0068] Comparative example: the width of the projection area 210 formed by the conductive layer 200 is 0 mm, the width of the positive electrode current collector is 8 mm, and the overlapping lengths of the head and tail ends of the negative electrode sheet and the projection area 210 of the positive electrode sheet are both 0 mm.

[0069] Solution 1: The width of the projection area 210 formed by the conductive layer 200 is 2 mm, the width of the positive electrode collector is 8 mm, and the overlapping lengths of the head and tail ends of the negative electrode sheet and the projection area 210 of the positive electrode sheet are both 4 mm.

[0070] Solution 2: The width of the projection area 210 formed by the conductive layer 200 is 3 mm, the width of the positive electrode current collector is 8 mm, and the overlapping lengths of the head and tail ends of the negative electrode sheet and the projection area 210 of the positive electrode sheet are both 4 mm.

[0071] Solution 3: The width of the projection area 210 formed by the conductive layer 200 is 4 mm, the width of the positive electrode collector is 8 mm, and the overlapping lengths of the head and tail ends of the negative electrode sheet and the projection area 210 of the positive electrode sheet are both 4 mm.

[0072] When the battery was charged and discharged for 500 times, the results of disassembling the battery were as follows:

[0073] Comparative example: moderate lithium deposition at the head and tail ends of the negative electrode sheet.

[0074] Option 1: No lithium deposition on the negative electrode.

[0075] Option 2: No lithium deposition on the negative electrode.

[0076] Option three: No lithium deposition on the negative electrode.

[0077] When the battery is charged and discharged for 1000 times, the results of disassembling the battery are as follows:

[0078] Comparative example: The head and tail ends of the negative electrode sheet are seriously lithium deposited.

[0079] Option 1: Slight lithium deposition at the head and tail ends of the negative electrode.

[0080] Option 2: No lithium deposition on the negative electrode.

[0081] Option three: No lithium deposition on the negative electrode.

[0082] It can be seen that adding the conductive layer 200 to the positive electrode current collector can effectively improve the lithium deposition on the negative electrode sheet.

[0083] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A positive electrode current collector, characterized in that: include: A substrate having a coating area on its surface for coating positive electrode coating; A conductive layer is embedded in the substrate. Along a direction perpendicular to the surface of the substrate, the projection of the conductive layer on the surface of the substrate forms a projection area. The projection area overlaps with the coating area and is located at the edge of the contour of the coating area. The conductivity of the conductive layer is lower than the conductivity of the positive electrode coating.

2. The positive electrode current collector according to claim 1, characterized in that: The positive electrode current collector is used for winding the battery core, the coating area has two width sides in the same direction as the width direction of the substrate, and the projection area is located at a contour edge position corresponding to at least one of the two width sides of the coating area.

3. The positive electrode current collector according to claim 2, characterized in that: The length of the projection area along the length direction of the substrate is 2 mm to 10 mm.

4. The positive electrode current collector according to claim 2, characterized in that: The length of the projection area along the width direction of the substrate is d, the length of the coating area along the width direction of the substrate is D, and the positive electrode current collector satisfies: 0.2D≤d≤0.5D.

5. The positive electrode current collector according to claim 4, characterized in that: Along the width direction of the substrate, the projection area is located in the middle of the coating area.

6. The positive electrode current collector according to claim 2, characterized in that: The projection area is located at the contour edge positions corresponding to the two width sides of the coating area.

7. The positive electrode current collector according to claim 1, characterized in that: The substrate includes a first layer and a second layer that overlap each other, and the conductive layer is located between the first layer and the second layer.

8. The positive electrode current collector according to claim 1, characterized in that: The positive electrode current collector is used for a laminated battery cell.

9. A polar belt, characterized in that include: A base tape is embedded with a plurality of conductive areas, wherein the plurality of conductive areas are sequentially spaced apart along the length direction of the base tape, the conductive area has a cutting position in the middle along the length direction of the base tape, the base tape is cut at the cutting position to form the positive electrode current collector according to any one of claims 2 to 6, and the conductive area is cut to form the conductive layer.

10. A battery, characterized in that: include: A positive electrode sheet, comprising the positive electrode collector according to any one of claims 1 to 9 and a positive electrode coating coated on the surface of the positive electrode collector.

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