Composite current collector, electrode plate, battery cell, preparation method of battery cell and detection method of battery cell

Abstract

The embodiment of the invention provides a composite current collector, an electrode plate, a battery cell and a preparation and detection method of the battery cell, and relates to the technical field of composite current collectors, the composite current collector comprises a heating layer and two metal layers, the heating layer is arranged between the two metal layers and is respectively connected with the metal layers, and a heating piece is arranged in the heating layer. Wherein the side, away from the heating layer, of at least one metal layer is provided with a coating area, and the heating area of the heating piece corresponds to the coating area. According to the composite current collector provided by the embodiment of the invention, the heating layer is uniformly heated through heating of the heating piece, and is uniformly transferred to the coating area, the temperature distribution is uniform, and the temperature difference at each position is small, so that the performance and the service life of a battery can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of composite current collectors, and particularly to a composite current collector, an electrode sheet, a battery cell, a preparation method and a detection method of the battery cell. Background Art

[0002] At present, power batteries are increasingly widely used in new energy vehicles and energy storage devices, and higher requirements are also put forward for aspects such as the performance of the batteries.

[0003] Generally, the optimal operating temperature range of the battery is 20°C to 30°C. To ensure that the battery quickly reaches the optimal operating temperature in a low-temperature environment, in related technologies, a heating component is added to the battery pack to preheat the battery cell.

[0004] However, the above preheating method has poor uniformity in heating each part of the battery cell, resulting in a large temperature difference everywhere inside the battery cell, which affects the performance and lifespan of the battery. Summary of the Invention

[0005] Based on this, the present application provides a composite current collector, an electrode sheet, a battery cell, a preparation method and a detection method of the battery cell to solve the problem that the existing preheating method has poor uniformity in heating each part of the battery cell, which affects the performance and lifespan of the battery.

[0006] In a first aspect, the present application provides a composite current collector, including a heating layer and two metal layers;

[0007] The heating layer is disposed between the two metal layers and is respectively connected to the metal layers. A heating element is provided in the heating layer;

[0008] Wherein, on one side of at least one metal layer facing away from the heating layer, there is a coating area, and the heating area of the heating element corresponds to the coating area.

[0009] In a possible implementation manner, the heating layer includes two base material layers. The heating element is disposed between the two base material layers and is respectively connected to the base material layers. The side of the base material layer facing away from the heating element is connected to the metal layer.

[0010] In a possible implementation manner, it further includes two first lead-out parts. The two first lead-out parts are located at the ends of the composite current collector and are correspondingly electrically connected to the two metal layers.

[0011] In a possible implementation manner, a support part is provided between the two first lead-out parts, and the support part is connected to the end of the heating layer.

[0012] In a possible implementation manner, it further includes a second lead-out part. The second lead-out part is located on one side of the coating area, and a part of the second lead-out part is located in the heating layer and is electrically connected to the heating element.

[0013] In a possible implementation, the heating element is a heating wire or a heating sheet.

[0014] In a possible implementation, the heating element is arranged in a curved shape.

[0015] In a second aspect, the present application further provides an electrode sheet, including any one of the composite current collectors provided in the first aspect.

[0016] In a possible implementation, the electrode sheet is a positive electrode sheet, and the thickness ratio between the base material layer and the metal layer in the positive electrode sheet is 5:1 to 7:1;

[0017] And / or, the electrode sheet is a negative electrode sheet, and the thickness ratio between the base material layer and the metal layer in the negative electrode sheet is 3:1 to 4.5:1.

[0018] In a third aspect, the present application further provides an electric core, including a plurality of electrode sheets and a plurality of separators. The plurality of electrode sheets are stacked in sequence, and adjacent electrode sheets are separated by separators. At least one of the electrode sheets is provided with any one of the composite current collectors provided in the first aspect.

[0019] In a fourth aspect, the present application further provides a method for manufacturing an electric core for the electric core provided in the third aspect, including:

[0020] Setting the number of the first electrode sheet with a composite current collector and the second electrode sheet without a heating function current collector;

[0021] Manufacturing the second electrode sheet, determining the heating demand and heat dissipation of the second electrode sheet, and obtaining the total heating amount;

[0022] Determining the heating parameters of the heating element in the first electrode sheet, and manufacturing the first electrode sheet;

[0023] Integrating the first electrode sheet, the second electrode sheet and the separator into an electric core module, and then packaging a plurality of electric core modules into an electric core.

[0024] In a possible implementation, determining the heating parameters of the heating element in the first electrode sheet includes:

[0025] Determining the heating power of the heating element;

[0026] Determining the resistance of the heating element;

[0027] Determining the resistivity, length, width and thickness of the heating element.

[0028] In a fifth aspect, the present application further provides a method for detecting an electric core for the electric core provided in the third aspect, including:

[0029] Collecting the potential signals of the positive electrode, the negative electrode and the heating element of the current electric core respectively to obtain a first potential, a second potential and a third potential;

[0030] If the difference between the third potential and the second potential is zero, it is determined that the heating function of the current battery cell is normal;

[0031] If the difference between the third potential and the second potential is equal to the difference between the first potential and the second potential, it is determined that the heating function of the current battery cell is abnormal, and an alarm signal is issued.

[0032] The composite current collector, electrode sheet, battery cell, preparation and detection methods of the battery cell provided by the present application. The composite current collector includes a heating layer and two metal layers. By arranging the heating layer between the two metal layers and connecting it to the metal layers respectively, and arranging a heating element in the heating layer, and arranging a coating area on the side of the metal layer away from the heating layer, and making the heating area of the heating element correspond to the coating area, the heating layer is uniformly heated by the heating element and uniformly transmitted to the coating area, with a uniform temperature distribution and a small temperature difference everywhere, so as to improve the performance and life of the battery. Description of the Drawings

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0034] Figure 1 It is a schematic cross-sectional structure diagram of the composite current collector provided by the embodiment of the present application;

[0035] Figure 2 It is an exploded view of the composite current collector provided by the embodiment of the present application;

[0036] Figure 3 It is an exploded view of the battery cell module provided by the embodiment of the present application;

[0037] Figure 4 It is a connection relationship diagram of the electrode sheet and the pole column provided by the embodiment of the present application;

[0038] Figure 5 It is a flowchart of the battery cell preparation method provided by the embodiment of the present application;

[0039] Figure 6 For Figure 5 The flowchart for determining the heating parameters in

[0040] Figure 7 It is a flowchart of the battery cell detection method provided by the embodiment of the present application;

[0041] Figure 8The first connection diagram of the battery cell detection circuit provided by the embodiment of the present application;

[0042] Figure 9 The second connection diagram of the battery cell detection circuit provided by the embodiment of the present application.

[0043] Reference numerals:

[0044] 10: Electrode plate;

[0045] 20: Separator;

[0046] 30: Terminal;

[0047] 100: Heating layer;

[0048] 200: Metal layer;

[0049] 210: Coating area;

[0050] 300: Heating element;

[0051] 400: First lead-out part;

[0052] 410: Support part;

[0053] 500: Second lead-out part. Detailed implementation manners

[0054] Here, the exemplary embodiments will be described in detail, and the examples are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. On the contrary, they are merely examples of methods and apparatuses consistent with some aspects of the present application as detailed in the appended claims.

[0055] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present application and the above drawings are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application described here, for example, can be implemented in an order other than those illustrated or described here. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device including a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0056] In the related art, a heating electrode sheet is disposed outside the battery cell or between multiple battery cells to preheat the battery cell. This form is similar to the existing PTC heating film. Attaching a heating film outside the battery cell easily causes uneven temperature inside the battery cell, which affects the cycle life of the battery cell after a long time. Among them, when setting a heating electrode sheet outside the battery cell, independent insulation protection is required, increasing the cost. There are also some battery cells with a heating area at the tab. The tabs are on both sides of the electrode sheet. When the length of the electrode sheet is long, the heating heat on both sides cannot be transferred to the middle of the electrode sheet, or the transfer is slow, which will also cause the problem of inconsistent temperature difference between the middle and both sides and different internal material circulation characteristics, ultimately affecting the cycle life of the battery cell.

[0057] In view of the above problems existing in the prior art, the present application provides a composite current collector, an electrode sheet, a battery cell, and preparation and detection methods for the battery cell. The composite current collector provided by the present application includes a heating layer and two metal layers. By disposing the heating layer between the two metal layers and connecting it to the metal layers respectively, and arranging a heating element in the heating layer, a coating area is provided on the side of the metal layer facing away from the heating layer, and the heating area of the heating element corresponds to the coating area. By heating with the heating element, the heating layer is uniformly heated and evenly transferred to the coating area, with uniform temperature distribution and small temperature difference everywhere, thereby improving the performance and life of the battery.

[0058] The technical solutions of the present application will be described in detail below with specific embodiments. These specific embodiments below can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments.

[0059] In a first aspect, please refer to Figures 1 - 5 As shown, an embodiment of the present application provides a composite current collector, including a heating layer 100 and two metal layers 200.

[0060] The heating layer 100 is disposed between the two metal layers 200 and is connected to the metal layers 200 respectively. A heating element 300 is provided in the heating layer 100.

[0061] Wherein, at least one of the metal layers 200 has a coating area 210 on the side facing away from the heating layer 100, and the heating area of the heating element 300 corresponds to the coating area 210.

[0062] The heating layer 100 in this embodiment is used for heating. It can be composed of a heating element 300 and a base material. The heating element 300 can be a heating wire, a heating sheet, etc., which can generate heat when powered on. The base material is used for insulating protection of the heating element 300 and can be made of insulating and voltage-resistant materials. The metal layer 200 in this embodiment is used for current collection and can be made of metal materials such as aluminum and copper.

[0063] Further, as Figure 2As shown, on the side of the metal layer 200 facing away from the heating layer 100, there is a coating area 210 for coating the active material layer, and the heating area where the heating element 300 is provided is adapted to the coating area 210.

[0064] In this way, when preheating is required, the heating element 300 generates heat to uniformly heat the heating layer 100, and the heat is uniformly transferred to the coating area 210, uniformly heating the entire coating area 210. The temperature distribution is uniform, and the temperature difference at each place is small, thereby improving the performance and cycle life of the battery.

[0065] Therefore, the battery electrode provided in the embodiment of the present application includes a heating layer 100 and two metal layers 200. By arranging the heating layer 100 between the two metal layers 200, connecting to the metal layers 200 respectively, arranging the heating element 300 in the heating layer 100, arranging the coating area 210 on the side of the metal layer 200 facing away from the substrate layer, and making the heating area of the heating element 300 correspond to the coating area 210, the heating layer 100 is uniformly heated by the heating element 300 and uniformly transferred to the coating area 210. The temperature distribution is uniform, and the temperature difference at each place is small, thereby improving the performance and life of the battery cell.

[0066] In a possible design, the heating layer 100 includes two substrate layers. The heating element 300 is arranged between the two substrate layers and connected to the substrate layers respectively. The side of the substrate layer facing away from the heating element 300 is connected to the metal layer 200.

[0067] Specifically, the substrate layer in this embodiment can be an insulating and voltage-resistant material such as polyethylene terephthalate (PET) or o-phenylphenol (OPP). The heating element 300 can be compounded between the two substrate layers by a molding process to form an integrated heating layer 100. Then, the metal layer 200 can be formed on the surface of the substrate layer on the side facing away from the heating element 300 by a deposition process, thereby forming a composite current collector, which is generally in a strip-shaped structure, facilitating mass production and processing, and having good product consistency.

[0068] In some embodiments, there are also two first lead-out parts 400. The two first lead-out parts 400 are located at the ends of the composite current collector and are correspondingly electrically connected to the two metal layers 200.

[0069] Specifically, as Figure 2 shown, the first lead-out part 400 is the tab, which is generally trapezoidal. The first lead-out part 400 is connected to the end of the composite current collector and can be integrally formed. The heating element 300 is not arranged in the first lead-out part 400. The first lead-out part 400 is also used to connect to the terminal 30.

[0070] Among them, for the specific shape, position, etc. of the first lead-out part 400, it can be determined according to actual needs and is not specifically limited in this embodiment.

[0071] Further, in this embodiment, a support portion 410 is provided between the two first lead portions 400, and the support portion 410 is connected to the end of the heating layer 100.

[0072] Specifically, as Figure 2 shown, the support portion 410 is used to support the first lead portion 400, and it can be integrally formed with the base material layer, which is convenient for the first lead portion 400 to be deposited on the support portion 410, thus facilitating production and processing.

[0073] In some embodiments, a second lead portion 500 is further included. The second lead portion 500 is located on one side of the coating area 310, and a part of the second lead portion 500 is located in the heating layer 100 and is electrically connected to the heating element 300.

[0074] Specifically, continuing as Figure 2 shown, the second lead portion 500 is used to lead out the positive and negative electrodes of the heating element 300. It is located on one side of the coating area 210, such as one side of the middle position between the two ends of the composite current collector, and a part of the second lead portion 500 extends into the heating layer 100, which is convenient for connecting with the heating element 300. The second lead portion 500 is also used to connect to a power source to supply power to the heating element 300.

[0075] Among them, for the specific shape, position, etc. of the second lead portion 500, it can be determined according to actual needs and is not specifically limited in this embodiment.

[0076] In some embodiments, the heating element 300 is a heating wire or a heating sheet.

[0077] Specifically, as Figure 2 shown, the heating element 300 can be a filamentous component made of copper, stainless steel or other high heat - generating metal materials.

[0078] Further, in this embodiment, the heating element 300 is arranged in a curved shape.

[0079] Specifically, as Figure 2 shown, the heating element 300 can be arranged in a serpentine shape on the base material layer to form a heating area.

[0080] Among them, for the specific parameters of the heating element 300, it can be determined according to actual design needs and is not specifically limited in this embodiment.

[0081] In a second aspect, an electrode sheet provided by an embodiment of the present application further includes the composite current collector provided in any of the above - mentioned embodiments.

[0082] Among them, the structure of the composite current collector has been introduced in detail in the above - mentioned embodiments and will not be elaborated here one by one.

[0083] Specifically, the active material layer can be evenly coated on the coating area 210 as needed to form electrode sheets, such as positive electrode sheets and negative electrode sheets. Among them, the materials of the metal layer 200 and the active material layer in the positive electrode sheet and the negative electrode sheet are different.

[0084] For the electrode sheet provided by the embodiment of the present application, by configuring a composite current collector, the composite current collector heats the heating layer 100 evenly through the heating element 300 and evenly transfers it to the coating area 210, with a uniform temperature distribution and a small temperature difference everywhere, thereby being able to improve the performance and lifespan of the battery cell.

[0085] Furthermore, in this embodiment, the electrode sheet is a positive electrode sheet, and the thickness ratio between the substrate layer and the metal layer 200 in the positive electrode sheet is 5:1 to 7:1.

[0086] And / or, the electrode sheet is a negative electrode sheet, and the thickness ratio between the substrate layer and the metal layer 200 in the negative electrode sheet is 3:1 to 4.5:1.

[0087] Among them, the thickness ratio between the substrate layer and the metal layer 200 can be determined according to different metal materials and different active materials, and there are no excessive restrictions in this embodiment.

[0088] In a third aspect, the embodiment of the present application further provides a battery cell, including a plurality of electrode sheets 10 and a plurality of separators 20. The plurality of electrode sheets 10 are stacked in sequence, and adjacent electrode sheets 10 are separated by the separator 20. At least one electrode sheet 10 is provided with the composite current collector provided in any of the above embodiments.

[0089] Among them, the structure of the composite current collector has been introduced in detail in the above embodiments, and will not be elaborated here one by one.

[0090] Specifically, as Figure 3 shown, the electrode sheet 10 includes a positive electrode sheet and a negative electrode sheet, which are arranged alternately and separated by the separator 20 therebetween to form a laminated battery cell, as Figure 5 shown, among which, a composite current collector is provided in the electrode sheet 10 near the middle position for preheating.

[0091] For the electrode sheet provided by the embodiment of the present application, by configuring a composite current collector, the composite current collector heats the heating layer 100 evenly through the heating element 300 and evenly transfers it to the coating area 210, with a uniform temperature distribution and a small temperature difference everywhere, thereby being able to improve the performance and lifespan of the battery cell.

[0092] In a fourth aspect, as Figure 6 shown, the embodiment of the present application further provides a method for manufacturing a battery cell for the battery cell provided in any of the above embodiments, including:

[0093] S600. Set the quantities of the first electrode sheet with a composite current collector and the second electrode sheet with a non-heating-function current collector.

[0094] Specifically, generally each battery cell stack assembly is composed of multiple stack sub-assemblies (i.e., battery cell modules), and each battery cell module contains a composite current collector with a heating function and multiple current collectors without a heating function. First, according to design requirements (such as size requirements, etc.), the number of the first electrode sheets with a heating function in the battery cell module can be determined as 1, and the number of the second electrode sheets without a heating function can be pre-determined as n to prepare for subsequent measurement of the heating demand.

[0095] S700. Prepare the second electrode sheet, determine the heating demand Φ1 and the heat dissipation Φ2 of the second electrode sheet, and obtain the total heating amount Φ.

[0096] Specifically, after the second electrode sheet is prepared, the heating demand Φ1 can be calculated according to the following formula:

[0097]

[0098] In the formula: C b - Specific heat capacity of the battery cell; m b - Weight of the composite current collector; n - Number of the second electrode sheets without a heating function; - Preset temperature rise. Among them, C b , n are known, m b can be measured, can be set, then Φ1 can be calculated.

[0099] Then, calculate the heat dissipation Φ2 according to the following formula:

[0100]

[0101] In the formula: A - Area of the current collector coating area; t f1 - Temperature inside the battery cell module near the electrode sheet with a heating function; t f2 - Temperature outside the battery cell module; n - Number of the second electrode sheets without a heating function; δ1 - Thickness of the positive current collector; λ1 - Thermal conductivity of the positive current collector; δ2 - Thickness of the negative current collector; λ2 - Thermal conductivity of the negative current collector; δ3 - Thickness of the separator; λ3 - Thermal conductivity of the separator; h - Heat transfer coefficient between the electrolyte and the surface of the current collector. Among them, δ1, λ1, δ2, λ2, δ3, λ3, h, n are known, A, t f1 and t f2 can be measured, then Φ2 can be calculated.

[0102] Finally, calculate the total heating amount Φ according to the following formula:

[0103]

[0104] Where: Φ1 - heating demand; Φ2 - heat loss. Among them, if Φ1 and Φ2 have been calculated, then Φ can be calculated.

[0105] S800. Determine the heating parameters of the heating element 300 in the first electrode sheet, and prepare the first electrode sheet.

[0106] Specifically, determine the heating parameters of the heating element 300 and select a model to prepare the first electrode sheet.

[0107] S900. Integrate the first electrode sheet, the second electrode sheet and the separator into a battery cell module, and then package multiple battery cell modules into a battery cell.

[0108] Specifically, arrange them alternately according to "positive electrode sheet - separator - negative electrode sheet - separator - positive electrode sheet" to form a battery cell module, and then package multiple battery cell modules into a battery cell.

[0109] In addition, after setting the number of the second electrode sheets of the current collector without heating function, simulation can also be carried out for verification to adjust the number in time.

[0110] It should be noted that when the heating element 300 in the electrode sheet with heating function has been developed and verified and becomes a mature product, at this time, it is more convenient to determine the number n of the second electrode sheets of the current collector without heating function.

[0111] The preparation method of the battery cell provided by the embodiment of the present application can provide a basis for the manufacture of the battery cell with heating function.

[0112] Further, in this embodiment, determining the heating parameters of the heating element 300 in the first electrode sheet includes:

[0113] S810. Determine the heating power of the heating element 300.

[0114] Specifically, the heating power P can be calculated according to the following formula:

[0115]

[0116] Where: t - preset heating time; η - heating efficiency. Among them, η is known and t can be set, then P can be calculated.

[0117] S820. Determine the resistance of the heating element 300.

[0118] Specifically, the resistance R can be calculated according to the following formula:

[0119]

[0120] Where: U - rated voltage. Among them, U can be set, then R can be calculated.

[0121] S830. Determine the resistivity, length, width, and thickness of the heating element 300.

[0122] Specifically, it can be determined according to the following formula:

[0123]

[0124] In the formula: ρ - resistivity of the heating wire; l - total length of the heating wire; w - width of the heating wire; t - thickness of the heating wire. Thus, the heating wire can be selected or prepared according to the parameters of ρ, l, w, and t.

[0125] In the fifth aspect, as Figures 7 - 9 shown, the embodiment of the present application further provides a detection method for a battery cell, which is used for the battery cell provided in any of the above embodiments and is used to detect whether the heating function in the battery cell is abnormal, including:

[0126] S101. Collect the potential signals of the positive electrode, negative electrode, and heating element 300 of the current battery cell respectively to obtain the first potential, the second potential, and the third potential.

[0127] Specifically, as Figure 8 shown, the battery cells U1, U2, U3,... Un are connected in series with each other, the resistor R represents the heating element 300, and R1, R2,... Rn are also connected in series with each other. The BMS system leads out three acquisition signals for each battery cell. Taking the first battery cell as an example, V1+ collects the positive electrode potential of the current battery cell, that is, the first potential, V2+ collects the positive electrode potential of the second battery cell. Because of the series connection relationship, V2+ is equal to V1-, that is, the second voltage, and R1+ collects the potential of the heating element 300 of the first battery cell, that is, the third potential. Therefore, the potential difference between V1+ and V2+ is equal to the voltage of the first battery cell, that is, the potential difference between the first potential and the second potential is the voltage of the battery cell.

[0128] S102. If the difference between the third potential and the second potential is zero, it is determined that the heating function of the current battery cell is normal.

[0129] Specifically, continuing as Figure 8 shown, when the battery cell is not out of control, due to the isolation and insulation of the base material layer, the heating element 300 is not conducted with the outer metal layer of the current collector, then the voltage between R1+ and V2+ is 0V, that is, there is no potential difference between the third potential and the second potential. At this time, it is determined that the heating function of the current battery cell is normal.

[0130] S103. If the difference between the third potential and the second potential is equal to the difference between the first potential and the second potential, it is determined that the heating function of the current battery cell is abnormal and an alarm signal is issued.

[0131] Specifically, as Figure 9As shown, when the battery cell undergoes thermal runaway, the substrate layer is abnormally damaged or ruptured. At this time, conduction is achieved through the electrolyte, enabling conduction between the heating element 300 and the outer metal layer of the positive electrode sheet of the current battery cell. At this time, R1+ will be equal to V1+, and the battery cell can still operate. Then, the voltage between R1+ and V2+ will become the voltage difference of the battery cell, that is, the voltage difference between the third potential and the second potential is the voltage of the current battery cell, which is used as a thermal runaway alarm signal.

[0132] The detection method of the battery cell provided by the embodiment of the present application can accurately and quickly determine whether there is an abnormality in the heating function of the battery cell, ensuring the safety of battery use.

[0133] After considering the specification and the application disclosed herein, those skilled in the art will readily conceive of other embodiments of the present application. The present application is intended to cover any variations, uses, or adaptations of the present application, which follow the general principles of the present application and include known common knowledge or conventional technical means in the technical field not disclosed in the present application. The specification and the embodiments are only regarded as exemplary, and the true scope and spirit of the present application are pointed out by the claims.

[0134] It should be understood that the present application is not limited to the exact structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the present application is only limited by the appended claims.

Claims

1. A composite current collector, characterized in that: It comprises a heating layer (100) and two metal layers (200); The heating layer (100) is arranged between the two metal layers (200) and is respectively connected to the metal layers (200), and a heating element (300) is provided in the heating layer (100); Wherein, at least one of the metal layers (200) has a coating area (210) on a side facing away from the heating layer (100), and a heating area of ​​the heating element (300) corresponds to the coating area (210).

2. The composite current collector according to claim 1, characterized in that: The heating layer (100) comprises two substrate layers, the heating element (300) is arranged between the two substrate layers and is respectively connected to the substrate layers, and the side of the substrate layer facing away from the heating element (300) is connected to the metal layer (200).

3. The composite current collector according to claim 1, characterized in that: It also includes two first lead-out portions (400), the two first lead-out portions (400) being located at the ends of the composite current collector and being electrically connected to the two metal layers (200) respectively.

4. The composite current collector according to claim 3, characterized in that: A support portion (410) is provided between the two first lead-out portions (400), and the support portion (410) is connected to an end portion of the heating layer (100).

5. The composite current collector according to claim 1, characterized in that: It also includes a second lead-out portion (500), the second lead-out portion (500) is located on one side of the coating area (310), and a portion of the second lead-out portion (500) is located in the heating layer (100) and is electrically connected to the heating element (300).

6. The composite current collector according to any one of claims 1 to 5, characterized in that: The heating element (300) is a heating wire or a heating plate.

7. The composite current collector according to claim 6, characterized in that: The heating element (300) is arranged in a curved shape.

8. An electrode sheet, characterized in that: Comprising the composite current collector according to any one of claims 2 to 7.

9. The electrode sheet according to claim 8, characterized in that: The electrode sheet is a positive electrode sheet, and the thickness ratio between the substrate layer and the metal layer (200) in the positive electrode sheet is 5:1 to 7:1; And / or, the electrode sheet is a negative electrode sheet, and the thickness ratio between the substrate layer and the metal layer (200) in the negative electrode sheet is 3:1 to 4.5:

1.

10. A battery cell, characterized in that: The invention comprises a plurality of electrode sheets (10) and a plurality of separators (20), wherein the plurality of electrode sheets (10) are stacked in sequence, and adjacent electrode sheets (10) are separated by the separators (20), and at least one of the electrode sheets (10) is provided with a composite current collector according to any one of claims 1 to 7.

11. A method for preparing a battery cell, used for the battery cell as claimed in claim 10, characterized in that: include: Setting the number of the first electrode sheet having the composite current collector and the second electrode sheet having no heating function current collector; preparing the second electrode sheet, determining the heating demand and heat loss of the second electrode sheet, and obtaining the total heating amount; Determining the heating parameters of the heating element (300) in the first electrode sheet, and preparing the first electrode sheet; The first electrode sheet, the second electrode sheet and the separator are integrated into a battery cell module, and then a plurality of the battery cell modules are packaged into a battery cell.

12. The method for preparing a battery cell according to claim 11, characterized in that: Determining the heating parameters of the heating element (300) in the first electrode sheet comprises: determining the heating power of the heating element (300); determining the resistance of the heating element (300); The resistivity, length, width and thickness of the heating element (300) are determined.

13. A method for detecting a battery cell, used for the battery cell as claimed in claim 10, characterized in that: include: respectively collecting potential signals of the positive electrode, the negative electrode and the heating element (300) of the current battery cell to obtain a first potential, a second potential and a third potential; If the difference between the third potential and the second potential is zero, it is determined that the heating function of the current battery cell is normal; If the difference between the third potential and the second potential is equal to the difference between the first potential and the second potential, it is determined that the heating function of the current battery cell is abnormal, and an alarm signal is issued.

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