Electrode plate, manufacturing method thereof and sodium ion battery

Abstract

The invention belongs to the technical field of sodium-ion batteries, and discloses an electrode plate, a manufacturing method thereof and a sodium-ion battery, the electrode plate comprises a composite current collector, and the composite current collector comprises a first metal layer, an insulating layer and a second metal layer which are arranged in sequence; the positive electrode coating is coated on the outer surface, far away from the insulating layer, of the first metal layer; the negative electrode coating is coated on the outer surface, far away from the insulating layer, of the second metal layer, and the projection of the negative electrode coating wraps the projection of the positive electrode coating in the length direction of the electrode plate; the positive tab connecting area is arranged at the position, which is not coated with the positive electrode coating, of the first metal layer; the negative tab connecting area is arranged at the position, not coated with the positive electrode coating, of the second metal layer, and the projection of the negative tab connecting area and the projection of the positive tab connecting area are not overlapped; the positive tab is connected with the positive tab connecting area; and the negative tab is connected with the negative tab connecting area. By changing the structure of the electrode plate, a negative current collector is cancelled, the use amount of the diaphragm is reduced, and the energy density and the safety of the battery cell are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of sodium ion batteries, and in particular relates to an electrode sheet, a manufacturing method thereof, and a sodium ion battery. Background Art

[0002] With the increasing popularity of electric vehicles, consumers are increasingly demanding longer-range driving. The energy density of batteries determines the range of electric vehicles. To alleviate people's "range anxiety," improving battery energy density has become a pressing issue in the battery industry. However, as battery cell energy density continues to increase, safety concerns are also gradually emerging. Among them, internal short circuits in batteries are an essential consideration for battery safety. Internal short circuits are primarily caused by direct contact between the positive and negative current collectors, which causes a sharp increase in the local temperature within the battery cell, leading to thermal runaway and increased battery safety risks. Summary of the Invention

[0003] In response to the above problems, the present invention proposes an electrode sheet, a manufacturing method thereof, and a sodium ion battery. By changing the structure of the electrode sheet, the use of a negative electrode current collector is eliminated, and the amount of diaphragm used is reduced, thereby improving the energy density and safety of the battery cell.

[0004] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions: In a first aspect, the present invention provides an electrode sheet, comprising: A composite current collector comprises a first metal layer, an insulating layer and a second metal layer arranged in sequence; A positive electrode coating is applied on the outer surface of the first metal layer away from the insulating layer; a negative electrode coating, applied on the outer surface of the second metal layer away from the insulating layer, and the projection of the negative electrode coating wraps the projection of the positive electrode coating in the length direction of the electrode sheet; A positive electrode tab connection area is provided at a position on the first metal layer where the positive electrode coating is not applied; A negative electrode tab connection area is provided at a position on the second metal layer where the positive electrode coating is not applied, and the projections of the negative electrode tab connection area and the positive electrode tab connection area do not overlap; A positive electrode tab connected to the positive electrode tab connection area; The negative electrode tab is connected to the negative electrode tab connection area.

[0005] The electrode sheet proposed in the above scheme includes a composite current collector, and a positive electrode coating and a negative electrode coating applied on both sides of the composite current collector; the composite current collector includes a first metal layer, an insulating layer and a second metal layer arranged in sequence. Since only a single composite current collector is used, the safety of the battery cell can be effectively increased, and the problem of direct contact between the positive electrode collector and the negative electrode collector causing an internal short circuit in the battery cell in the prior art when the internal structure of the battery cell is severely damaged by acupuncture, extrusion, etc. is avoided. In addition, the electrode sheet in the present invention eliminates the conventional negative electrode copper foil current collector, which can improve the energy density of the battery cell. When the battery cell is produced by the winding process, only one layer of diaphragm is required, which reduces the amount of diaphragm used and reduces the cost. The demand for the unwinding shaft of the winding machine is also reduced in production, reducing the equipment investment cost. The electrode sheet in the present invention can be realized on a conventional winding machine to achieve single-machine, multi-core synchronous winding.

[0006] In combination with the first aspect, optionally, the positive electrode tab connection area is provided at one end of the first metal layer in the length direction; the negative electrode tab connection area is provided at one end of the second metal layer in the length direction.

[0007] In the above scheme, the specific locations of the positive electrode ear connection area and the negative electrode ear connection area are provided. Subsequently, the ears need to be led out on the left and right sides in the length direction of the electrode sheet, which is suitable for the production of cylindrical battery cells.

[0008] In combination with the first aspect, optionally, the positive electrode tab connection area is provided at one end of the first metal layer in the width direction; and the negative electrode tab connection area is provided at one end of the second metal layer in the width direction.

[0009] In the above scheme, the specific positions of the positive electrode ear connection area and the negative electrode ear connection area are provided. Subsequently, the ears need to be led out on the left and right sides in the width direction of the electrode sheet. It is not only suitable for the production of cylindrical battery cells, but also for the production of square battery cells.

[0010] In combination with the first aspect, optionally, the positive tab connection area and the negative tab connection area are located on the same side of the electrode sheet.

[0011] In the above scheme, since the positive tab connection area and the negative tab connection area are located on the same side of the electrode sheet, the use of the same-side tabs is achieved, which can optimize the space utilization of the battery cell and improve the volume energy density of the battery cell.

[0012] In combination with the first aspect, optionally, the material of the positive electrode coating is a sodium electrode material.

[0013] In the above scheme, considering the resource reserves, the resource reserves of sodium are significantly higher than those of lithium, and the cost of using sodium battery materials is lower than that of lithium battery, which can reduce production costs.

[0014] In combination with the first aspect, optionally, the material of the negative electrode coating is a hard carbon material.

[0015] In the above scheme, the selection of hard carbon material as the material for the negative electrode coating can not only improve the electrochemical performance of the sodium ion battery, have excellent rate performance and good cycle stability, but also improve thermal stability and improve battery technology and cost.

[0016] In combination with the first aspect, optionally, the material of the first metal layer and the second metal layer is aluminum or copper, and the material of the insulating layer is PET, PP or PI.

[0017] Conventional current collectors will produce large burrs when punctured, which can easily cause internal short circuits and thermal runaway, and there is a risk of battery explosion and fire. The composite current collector in the above scheme produces small burrs when punctured, and the PET layer will have a short-circuit effect, which can control the short-circuit current from increasing and effectively control battery thermal runaway and even explosion and fire.

[0018] In a second aspect, the present invention provides a method for manufacturing an electrode sheet, comprising: preparing a composite current collector, the composite current collector comprising a first metal layer, an insulating layer, and a second metal layer arranged in sequence; Applying a positive electrode slurry on an outer surface of the first metal layer away from the insulating layer using a first coating process, and baking the slurry at a high temperature to obtain a positive electrode coating and a positive electrode tab connection area; the positive electrode tab connection area is located at a position on the first metal layer where the positive electrode coating is not applied; A negative electrode slurry is applied on an outer surface of the second metal layer away from the insulating layer using a second coating process, and after high-temperature baking, a negative electrode coating and a negative electrode tab connection area are obtained, wherein the projection of the negative electrode coating wraps the projection of the positive electrode coating in the length direction of the electrode sheet; the negative electrode tab connection area is located at a position on the second metal layer where the positive electrode coating is not applied, and the projections of the negative electrode tab connection area and the positive electrode tab connection area do not overlap; connecting the positive electrode tab to the positive electrode tab connection area; Connect the negative electrode tab to the negative electrode tab connection area.

[0019] In the above scheme, a method for manufacturing an electrode sheet is provided. The electrode sheet manufactured based on this manufacturing method includes a composite current collector, and a positive electrode coating and a negative electrode coating applied on both sides of the composite current collector; the composite current collector includes a first metal layer, an insulating layer, and a second metal layer arranged in sequence. Since only a single composite current collector is used, the safety of the battery cell can be effectively increased, and the problem of direct contact between the positive electrode collector and the negative electrode collector causing an internal short circuit in the battery cell in the prior art is avoided when the internal structure of the battery cell is seriously damaged by acupuncture, extrusion, etc. In addition, the electrode sheet of the present invention eliminates the conventional negative electrode copper foil current collector, which can improve the energy density of the battery cell. When the battery cell is produced by the winding process, only one layer of diaphragm is required, which reduces the amount of diaphragm used and reduces the cost. The demand for the winding machine unwinding shaft is also reduced during production, reducing the equipment investment cost. The electrode sheet of the present invention can be realized on a conventional winding machine to achieve single-machine, multi-core synchronous winding.

[0020] In combination with the second aspect, optionally, the first coating process is an intermittent coating process, and several positive electrode coatings are produced on the first metal layer. There are blank areas between adjacent positive electrode coatings in the length direction of the electrode sheet, and the second coating process is a continuous coating process.

[0021] In the above scheme, the specific implementation process of the first coating and the second coating is given. The functions of the blank area include: (1) making the projection of the negative electrode coating wrap the projection of the positive electrode coating in the length direction of the electrode sheet; (2) serving as the positive electrode ear connection area.

[0022] In combination with the second aspect, optionally, the first coating process and the second coating process are both intermittent coating processes, and a number of positive electrode coatings and negative electrode coatings are produced on the first metal layer and the second metal layer. There are blank areas in the length direction of the electrode sheet between adjacent positive electrode coatings, and there are blank areas in the length direction of the electrode sheet between adjacent negative electrode coatings.

[0023] In the above scheme, the specific implementation process of the first coating and the second coating is given. The functions of the blank area include: (1) making the projection of the negative electrode coating wrap the projection of the positive electrode coating in the length direction of the electrode sheet; (2) it can be used as the positive electrode ear connection area and the negative electrode ear connection area.

[0024] In combination with the second aspect, optionally, the positive electrode tab connection area is provided at one end of the first metal layer in the length direction; the negative electrode tab connection area is provided at one end of the second metal layer in the length direction; In the above scheme, the specific locations of the positive electrode ear connection area and the negative electrode ear connection area are provided. Subsequently, the ears need to be led out on the left and right sides in the length direction of the electrode sheet, which is suitable for the production of cylindrical battery cells.

[0025] In combination with the second aspect, optionally, the positive electrode tab connection area is provided at one end of the first metal layer in the width direction; the negative electrode tab connection area is provided at one end of the second metal layer in the width direction.

[0026] In the above scheme, the specific positions of the positive electrode ear connection area and the negative electrode ear connection area are provided. Subsequently, the ears need to be led out on the left and right sides in the width direction of the electrode sheet. It is not only suitable for the production of cylindrical battery cells, but also for the production of square battery cells.

[0027] In combination with the second aspect, optionally, the positive tab connection area and the negative tab connection area are located on the same side of the electrode sheet.

[0028] In the above scheme, since the positive tab connection area and the negative tab connection area are located on the same side of the electrode sheet, the use of the same-side tabs is achieved, which can optimize the space utilization of the battery cell and improve the volume energy density of the battery cell.

[0029] In a third aspect, the present invention provides a sodium ion battery, comprising: The electrode sheet described in any one of the first aspects; The diaphragm covers the front side or the back side of the electrode sheet.

[0030] In the above scheme, a specific structure of a sodium ion battery is provided, in which the electrode sheet of the sodium ion battery includes a composite current collector, and a positive electrode coating and a negative electrode coating applied on both sides of the composite current collector; the composite current collector includes a first metal layer, an insulating layer, and a second metal layer arranged in sequence. Since only a single composite current collector is used, the safety of the battery cell can be effectively increased, and the problem of direct contact between the positive electrode collector and the negative electrode collector causing an internal short circuit in the battery cell when the internal structure of the battery cell is severely damaged by needle puncture, extrusion, etc. in the prior art is avoided. In addition, the electrode sheet of the present invention eliminates the conventional negative electrode copper foil current collector, which can improve the energy density of the battery cell. When the battery cell is produced using a winding process, only one layer of diaphragm is required, which reduces the amount of diaphragm used and reduces costs. The demand for the winding machine unwinding shaft is also reduced during production, reducing the equipment investment cost. The electrode sheet of the present invention can be realized on a conventional winding machine to achieve single-machine, multi-core synchronous winding.

[0031] Compared with the prior art, the present invention has the following beneficial effects: The electrode sheet proposed in the present invention includes a composite current collector, and positive and negative electrode coatings applied on both sides of the composite current collector. The composite current collector comprises a first metal layer, an insulating layer, and a second metal layer arranged in sequence. Since only a single composite current collector is used, the safety of the battery cell is effectively improved, avoiding the problem of direct contact between the positive and negative current collectors, which can cause internal short circuits in the battery cell when the internal structure of the battery cell is severely damaged by needle puncture, extrusion, or other similar means. Furthermore, the electrode sheet of the present invention eliminates the conventional negative copper foil current collector, thereby increasing the energy density of the battery cell.

[0032] When using a winding process to produce battery cells, only one layer of separator is required, reducing separator usage and costs. This also reduces the need for winding machine unwinding shafts, lowering equipment investment costs. The electrode sheet of the present invention can be wound simultaneously on a single conventional winding machine, with multiple cores. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive work, among which: Figure 1 This is a schematic structural diagram of an electrode sheet according to an embodiment of the present invention; Figure 2 A schematic diagram comparing the structural differences between a current collector in the prior art and a composite current collector in the present invention in one embodiment of the present invention; Figure 3 This is a schematic diagram of the front and back structures of an electrode sheet according to an embodiment of the present invention; Figure 4 This is a second schematic diagram of the front and back structures of an electrode sheet according to an embodiment of the present invention; Figure 5 This is a third schematic diagram of the front and back structures of an electrode sheet according to an embodiment of the present invention; Figure 6 This is a fourth schematic diagram of the front and back structures of an electrode sheet according to an embodiment of the present invention; Figure 7 This is a fifth schematic diagram of the front and back structures of an electrode sheet according to an embodiment of the present invention; Figure 8 This is a schematic diagram of the structure of an electrode sheet after winding into a core according to an embodiment of the present invention; In the picture: 1. Composite current collector, 101. First metal layer, 102. Insulating layer, 103. Second metal layer, 2. Positive electrode ear, 3. Positive electrode coating, 4. Negative electrode ear, 5. Negative electrode coating, 6. Separator, 7. Winding needle. DETAILED DESCRIPTION

[0034] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0035] Unless otherwise specifically stated, the relative arrangement of the parts and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to actual proportional relationships. The techniques, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the techniques, methods and equipment should be considered as part of the authorization specification. In all examples shown and discussed here, any specific values ​​should be interpreted as being merely exemplary, not as limitations. Therefore, other examples of the exemplary embodiments may also include different values. It should be noted that similar numbers and letters represent similar items in the following figures, and therefore, once an item is defined in one figure, it does not need to be further discussed in subsequent figures.

[0036] In the description of the present invention, "several" means more than one, "plurality" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" in the description is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0037] In the description of the present invention, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the exemplary expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0038] The application principle of the present invention is described in detail below with reference to the accompanying drawings. Example 1

[0039] An embodiment of the present invention provides an electrode sheet, such as Figure 1As shown, including: The composite current collector 1 includes a first metal layer 101, an insulating layer 102 and a second metal layer 103 arranged in sequence. For a specific structure, see Figure 2 (B) A positive electrode coating 3 is coated on the outer surface of the first metal layer 101 away from the insulating layer 102; A negative electrode coating 5 is applied on the outer surface of the second metal layer 103 away from the insulating layer 102, and the projection of the negative electrode coating 5 wraps the projection of the positive electrode coating 3 in the length direction of the electrode sheet; The positive electrode tab connection area is provided at a position on the first metal layer 101 where the positive electrode coating 3 is not coated; The negative electrode tab connection area is provided at a position on the second metal layer 103 where the positive electrode coating 3 is not applied, and the projections of the negative electrode tab connection area and the positive electrode tab connection area do not overlap; A positive electrode tab 2, connected to the positive electrode tab connection area; The negative electrode tab 4 is connected to the negative electrode tab connection area.

[0040] The electrode sheet proposed in the above scheme includes a composite current collector 1, and a positive electrode coating 3 and a negative electrode coating 5 coated on both sides of the composite current collector 1; the composite current collector 1 includes a first metal layer 101, an insulating layer 102, and a second metal layer 103 arranged in sequence. Since only a single composite current collector 1 is used, the safety of the battery cell can be effectively increased, avoiding the problem of direct contact between the positive electrode current collector and the negative electrode current collector causing an internal short circuit in the battery cell when the internal structure of the battery cell is severely damaged by acupuncture, extrusion, etc. in the prior art. The structure of the current collector in the prior art is shown in FIG. Figure 2 (A) in the figure. Furthermore, the electrode sheet of the present invention eliminates the conventional negative electrode copper foil current collector, thereby increasing the energy density of the battery cell. When using a winding process to produce battery cells, only one layer of separator 6 is required, reducing separator 6 usage and lowering costs. This also reduces the need for a winding machine unwinding shaft, lowering equipment investment costs. The electrode sheet of the present invention can be wound simultaneously on a single conventional winding machine, with multiple cores.

[0041] In a specific implementation of the embodiment of the present invention, the positive tab connection area is provided at one end of the first metal layer 101 in the length direction; the negative tab connection area is provided at one end of the second metal layer 103 in the length direction.

[0042] In the above scheme, the specific positions of the positive tab connection area and the negative tab connection area are provided. During the specific implementation process, the positive tab connection area and the negative tab connection area are respectively located at the two ends of the length direction of the electrode sheet. Subsequently, the tabs need to be led out on the left and right sides of the length direction of the electrode sheet, which is suitable for the production of cylindrical battery cells.

[0043] In a specific implementation of the embodiment of the present invention, the positive tab connection area is provided at one end of the first metal layer 101 in the width direction; the negative tab connection area is provided at one end of the second metal layer 103 in the width direction.

[0044] In the above scheme, the specific positions of the positive electrode ear connection area and the negative electrode ear connection area are provided. Subsequently, the ears need to be led out on the left and right sides in the width direction of the electrode sheet. It is not only suitable for the production of cylindrical battery cells, but also for the production of square battery cells.

[0045] In a specific implementation of the embodiment of the present invention, the positive tab connection area and the negative tab connection area are located on the same side of the electrode sheet.

[0046] In the above scheme, since the positive tab connection area and the negative tab connection area are located on the same side of the electrode sheet, the use of the same-side tabs is achieved, which can optimize the space utilization of the battery cell and improve the volume energy density of the battery cell.

[0047] In a specific implementation of the embodiment of the present invention, the material of the positive electrode coating 3 is a sodium electrode material.

[0048] In the above scheme, considering the resource reserves, the resource reserves of sodium are significantly higher than those of lithium, and the cost of using sodium battery materials is lower than that of lithium battery, which can reduce production costs.

[0049] In a specific implementation of the embodiment of the present invention, the material of the negative electrode coating 5 is a hard carbon material.

[0050] In the above scheme, the hard carbon material is selected as the material of the negative electrode coating 5, which can not only improve the electrochemical performance of the sodium ion battery, have excellent rate performance and good cycle stability, but also improve the thermal stability and improve the battery process and cost.

[0051] In one embodiment of the present invention, the first metal layer 101 and the second metal layer 103 are made of aluminum or copper, and the insulating layer 102 is made of PET, PP, or PI. In practice, copper foil is typically used as the negative electrode current collector for lithium batteries, as lithium and aluminum alloy at low potentials. In contrast, sodium-ion batteries can use the more affordable aluminum foil as the current collector for both the positive and negative electrodes, as sodium does not alloy with aluminum at low potentials. Example 2

[0052] An embodiment of the present invention provides a method for manufacturing an electrode sheet, comprising the following steps: (1) preparing a composite current collector 1, wherein the composite current collector 1 comprises a first metal layer 101, an insulating layer 102, and a second metal layer 103 arranged in sequence; (2) applying a positive electrode slurry on the outer surface of the first metal layer 101 away from the insulating layer 102 by a first coating process, and baking at a high temperature to obtain a positive electrode coating 3 and a positive electrode tab connection area; the positive electrode tab connection area is located at a position on the first metal layer 101 where the positive electrode coating 3 is not applied; (3) A negative electrode slurry is coated on the outer surface of the second metal layer 103 away from the insulating layer 102 using a second coating process, and after high-temperature baking, a negative electrode coating 5 and a negative electrode ear connection area are obtained, and the projection of the negative electrode coating 5 wraps the projection of the positive electrode coating 3 in the length direction of the electrode sheet; the negative electrode ear connection area is located at a position on the second metal layer 103 where the positive electrode coating 3 is not coated, and the projections of the negative electrode ear connection area and the positive electrode ear connection area do not overlap. (4) connecting the positive electrode tab to the positive electrode tab connection area; (5) Connecting the negative electrode tab to the negative electrode tab connection area.

[0053] The above scheme provides a method for manufacturing an electrode sheet. The electrode sheet produced based on this method includes a composite current collector 1, and a positive electrode coating 3 and a negative electrode coating 5 applied on both sides of the composite current collector 1. The composite current collector 1 includes a first metal layer 101, an insulating layer 102, and a second metal layer 103 arranged in sequence. Since only a single composite current collector 1 is used, the safety of the battery cell is effectively improved, avoiding the problem of direct contact between the positive and negative current collectors, which can cause internal short circuits in the battery cell when the internal structure of the battery cell is severely damaged by needle puncture, extrusion, etc. in the prior art. The electrode sheet of the present invention also eliminates the conventional negative electrode copper foil current collector, which can improve the energy density of the battery cell. When the battery cell is produced using a winding process, only one layer of separator 6 is required, reducing the amount of separator 6 used and lowering costs. This also reduces the need for a winding machine unwinding shaft during production, reducing equipment investment costs. The electrode sheet of the present invention can be wound simultaneously on a single conventional winding machine with multiple cores.

[0054] In a specific implementation of the embodiment of the present invention, the first coating process is an intermittent coating process, and several positive electrode coatings 3 are produced on the first metal layer 101. There are blank areas between adjacent positive electrode coatings 3 in the length direction of the electrode sheet, and the second coating process is a continuous coating process.

[0055] In the above scheme, the specific implementation process of the first coating and the second coating is given. The functions of the blank area include: (1) making the projection of the negative electrode coating 5 wrap the projection of the positive electrode coating 3 in the length direction of the electrode sheet; (2) serving as the positive electrode ear connection area.

[0056] In a specific implementation of an embodiment of the present invention, the first coating process and the second coating process are both intermittent coating processes, and a plurality of positive electrode coatings 3 and negative electrode coatings 5 ​​are produced on the first metal layer 101 and the second metal layer 103. There are blank areas between adjacent positive electrode coatings 3 in the length direction of the electrode sheet, and there are blank areas between adjacent negative electrode coatings 5 ​​in the length direction of the electrode sheet.

[0057] In the above scheme, the specific implementation process of the first coating and the second coating is given. The functions of the blank area include: (1) making the projection of the negative electrode coating 5 wrap the projection of the positive electrode coating 3 in the length direction of the electrode sheet; (2) it can be used as the positive electrode ear connection area and the negative electrode ear connection area.

[0058] In a specific implementation of the embodiment of the present invention, the positive tab connection area is provided at one end of the first metal layer 101 in the length direction; the negative tab connection area is provided at one end of the second metal layer 103 in the length direction, and the projections of the positive tab connection area and the negative tab connection area do not overlap; In the above scheme, the specific locations of the positive electrode ear connection area and the negative electrode ear connection area are provided. Subsequently, the ears need to be led out on the left and right sides in the length direction of the electrode sheet, which is suitable for the production of cylindrical battery cells.

[0059] In a specific implementation of the embodiment of the present invention, the positive tab connection area is provided at one end of the first metal layer 101 in the width direction; the negative tab connection area is provided at one end of the second metal layer 103 in the width direction, and the projections of the positive tab connection area and the negative tab connection area do not overlap.

[0060] In the above scheme, the specific positions of the positive electrode ear connection area and the negative electrode ear connection area are provided. Subsequently, the ears need to be led out on the left and right sides in the width direction of the electrode sheet. It is not only suitable for the production of cylindrical battery cells, but also for the production of square battery cells.

[0061] In a specific implementation of the embodiment of the present invention, the positive tab connection area and the negative tab connection area are located on the same side of the electrode sheet.

[0062] In the above scheme, since the positive tab connection area and the negative tab connection area are located on the same side of the electrode sheet, the use of the same-side tabs is achieved, which can optimize the space utilization of the battery cell and improve the volume energy density of the battery cell.

[0063] The following is a specific embodiment, and Figure 3-Figure 7 , the manufacturing method in the embodiment of the present invention is described in detail.

[0064] Step 1: Prepare a composite current collector 1; The composite current collector 1 has a PET base film in the middle and aluminum layers are plated on both sides of the PET base film. The composite current collector 1 can improve the safety of the battery cell. Step 2: Extrusion coating; Since the baking temperatures of the positive electrode coating 3 and the negative electrode coating 5 are different (the temperature of the positive electrode coating 3 is higher than that of the negative electrode coating 5), the positive electrode slurry is first applied to the first metal layer 101 (defined as the A side) using the coating head, and then baked in the coating oven at high temperature to obtain the positive electrode coating 3; then the negative electrode slurry is applied to the second metal layer 103 (defined as the B side) using the coating tail, and then baked in the coating oven to obtain the negative electrode coating 5. The coating diagram is shown in FIG. Figure 3 As shown, different coating pads are used at the coating head and tail to control the coating in the width direction of the electrode sheet, that is, Figure 3 In Ⓐ (leaving blank space for coating the positive electrode tab) and Ⓓ (leaving blank space for coating the negative electrode tab), the coating in the length direction of the electrode sheet is controlled by intermittent blanking of the coating head and continuous (or intermittent) coating at the coating tail (realizing that the projection of the negative electrode coating 5 wraps the projection of the positive electrode coating 3 in the length direction of the electrode sheet), that is, Figure 3 In the middle, Ⓑ (used to achieve the negative electrode wrapped positive electrode) and Ⓒ (the positive electrode material area is coated and left blank). According to the requirements of the subsequent winding or lamination process, the positive end coating can be intermittently coated with a fixed length during the coating process to control the electrode sheet length.

[0065] According to the subsequent battery cell manufacturing requirements, there are several specific coating methods: a) If producing cylindrical batteries Both positive and negative electrodes can be coated intermittently, and only one tab is required for each of the positive and negative electrodes. Figure 4 As shown. You can also use intermittent coating for the positive electrode and continuous coating for the negative electrode, and then you need to lead out the tabs on the left and right sides of the electrode, as shown. Figure 5 The red wireframe is a schematic diagram of the subsequent tab lead-out.

[0066] b) If producing square cells Whether winding or lamination is used, the tabs are produced from both sides of the electrode sheet width direction, then the positive electrode needs to be coated intermittently, and the negative electrode needs to be coated continuously. Winding or lamination only needs to control the length of the positive electrode coating layer in the coating direction and the spacing of the positive electrode coating layer to control the cell length and the positive and negative electrode coating. Winding process such as Figure 5 As shown, the lamination process is as follows Figure 6 As shown, the red wireframe is a schematic diagram of the subsequent production of the tab lead.

[0067] Step 3: Roll-press the electrode sheet obtained by coating in step 2, and roll-weld the positive electrode ear 2 and the negative electrode ear 4 (the material of the ear and the coating material are consistent) on the blank space between the positive and negative electrode coatings of the electrode sheet or the blank space outside the coating layer of the first metal layer 101 / the second metal layer 103. Figure 4 and Figure 5As shown in the red frame, the above diagram shows the way of producing the tabs on both sides. If the tabs are produced on the same side, the tabs need to be intermittently rolled on the same side of the electrode sheet, such as Figure 7 As shown in the red frame.

[0068] Step 4: According to the design requirements, the electrode sheet obtained in step 3 can be laser cut or marked. Figure 6 The middle A side shows the state of the tab after laser cutting. Example 3

[0069] An embodiment of the present invention provides a sodium ion battery, comprising: The electrode sheet according to any one of embodiment 1; The diaphragm 6 covers the front or back side of the electrode sheet.

[0070] The above scheme provides a specific structure of a sodium-ion battery. The electrode sheet in this sodium-ion battery includes a composite current collector 1, and a positive electrode coating 3 and a negative electrode coating 5 applied on both sides of the composite current collector 1. The composite current collector 1 comprises a first metal layer 101, an insulating layer 102, and a second metal layer 103 arranged in sequence. Since only a single composite current collector 1 is used, the safety of the battery cell is effectively improved, avoiding the problem of direct contact between the positive and negative current collectors, which can cause internal short circuits in the battery cell when the internal structure of the battery cell is severely damaged by needle puncture, extrusion, or other similar means. Furthermore, the electrode sheet of the present invention eliminates the conventional negative electrode copper foil current collector, thereby increasing the energy density of the battery cell. When the battery cell is produced using a winding process, only one layer of separator 6 is required, reducing separator 6 usage and lowering costs. This also reduces the need for a winding machine unwinding spindle during production, reducing equipment investment costs. The electrode sheet of the present invention can be wound simultaneously on a single conventional winding machine, with multiple cores.

[0071] The method for preparing a sodium ion battery in an embodiment of the present invention includes: Step 1: Use a clamping device to clamp a layer of separator 6 and an electrode sheet, adjust the coating of the separator 6 and the negative electrode coating 5, and rotate the clamping device to obtain a winding core; Step 2: Directly weld the positive electrode tab 2, the negative electrode tab 4 and the cover plate; Step 3: Bend the welded positive electrode ear 2 and negative electrode ear 4, wrap the core with film, then place them into the shell, weld the cover plate to the periphery of the shell, and form a finished dry battery cell.

[0072] like Figure 8 The figure shows the structure of the electrode sheet after winding. The specific implementation is as follows: 1. The winding machine clamps a layer of separator 6 and electrode sheet through the winding needle 7, and the winding needle 7 rotates to obtain a winding core; because the coating has controlled the coating problem of the positive electrode coating 3 and the negative electrode coating 5, winding only needs to adjust the coating of the separator 6 and the negative electrode coating 5. Figure 8 As shown, this winding method uses only one layer of separator 6. Compared with the traditional two-layer separator 6 winding process, the coating difficulty is reduced, and there is no need to consider the alignment of the two rolls of separator 6. The use of a single layer of separator 6 reduces the amount of separator 6 used and improves the mass energy density of the battery cell.

[0073] 2. For the coiled core obtained in step 1, the tabs and cover plates are welded. The positive tab 2, the negative tab 4 and the cover plate 8 are directly laser welded to eliminate the conventional connecting piece, reduce the mass of the battery cell and improve the energy density.

[0074] 3. Bend the positive and negative tabs 2 and 4 welded in step 2, wrap them in film, and then install them into the casing. The cover plate is welded to the casing perimeter to obtain the finished dry cell. Subsequent processes such as helium testing, baking, short-circuit testing, liquid injection, formation, and capacity separation are performed in the same manner as for conventional square aluminum-cased cells.

[0075] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying 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 protection content of the present invention.

[0076] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. An electrode sheet, characterized in that: include: A composite current collector comprises a first metal layer, an insulating layer and a second metal layer arranged in sequence; A positive electrode coating is applied on the outer surface of the first metal layer away from the insulating layer; a negative electrode coating, applied on the outer surface of the second metal layer away from the insulating layer, and the projection of the negative electrode coating wraps the projection of the positive electrode coating in the length direction of the electrode sheet; A positive electrode tab connection area is provided at a position on the first metal layer where the positive electrode coating is not applied; A negative electrode tab connection area is provided at a position on the second metal layer where the positive electrode coating is not applied, and the projections of the negative electrode tab connection area and the positive electrode tab connection area do not overlap; A positive electrode tab connected to the positive electrode tab connection area; The negative electrode tab is connected to the negative electrode tab connection area.

2. The electrode sheet according to claim 1, wherein: The positive electrode tab connection area is arranged at one end of the first metal layer in the length direction; the negative electrode tab connection area is arranged at one end of the second metal layer in the length direction.

3. The electrode sheet according to claim 1, wherein: The positive electrode tab connection area is arranged at one end of the first metal layer in the width direction; the negative electrode tab connection area is arranged at one end of the second metal layer in the width direction.

4. The electrode sheet according to claim 3, characterized in that: The positive tab connection area and the negative tab connection area are located on the same side of the electrode sheet.

5. The electrode sheet according to claim 1, characterized in that: The material of the positive electrode coating is sodium electrode material.

6. The electrode sheet according to claim 1, characterized in that: The material of the negative electrode coating is a hard carbon material.

7. The electrode sheet according to claim 1, characterized in that: The materials of the first metal layer and the second metal layer are aluminum or copper, and the material of the insulating layer is PET, PP or PI.

8. A method for manufacturing an electrode sheet, characterized in that: include: preparing a composite current collector, the composite current collector comprising a first metal layer, an insulating layer, and a second metal layer arranged in sequence; Applying a positive electrode slurry on an outer surface of the first metal layer away from the insulating layer using a first coating process, and baking the slurry at a high temperature to obtain a positive electrode coating and a positive electrode tab connection area; the positive electrode tab connection area is located at a position on the first metal layer where the positive electrode coating is not applied; A negative electrode slurry is applied on an outer surface of the second metal layer away from the insulating layer using a second coating process, and after high-temperature baking, a negative electrode coating and a negative electrode tab connection area are obtained, wherein the projection of the negative electrode coating wraps the projection of the positive electrode coating in the length direction of the electrode sheet; the negative electrode tab connection area is located at a position on the second metal layer where the positive electrode coating is not applied, and the projections of the negative electrode tab connection area and the positive electrode tab connection area do not overlap; connecting the positive electrode tab to the positive electrode tab connection area; Connect the negative electrode tab to the negative electrode tab connection area.

9. The method for manufacturing an electrode sheet according to claim 8, wherein: The first coating process is an intermittent coating process, in which several positive electrode coatings are produced on the first metal layer, and there are blank areas between adjacent positive electrode coatings in the length direction of the electrode sheet; the second coating process is a continuous coating process.

10. The method for manufacturing an electrode sheet according to claim 8, wherein: The first coating process and the second coating process are both intermittent coating processes, and several positive electrode coatings and negative electrode coatings are produced on the first metal layer and the second metal layer. There are blank areas between adjacent positive electrode coatings in the length direction of the electrode sheet, and there are blank areas between adjacent negative electrode coatings in the length direction of the electrode sheet.

11. The method for manufacturing an electrode sheet according to claim 8, wherein: The positive electrode tab connection area is arranged at one end of the length direction of the first metal layer; the negative electrode tab connection area is arranged at one end of the length direction of the second metal layer; or, the positive electrode tab connection area is arranged at one end of the width direction of the first metal layer; the negative electrode tab connection area is arranged at one end of the width direction of the second metal layer.

12. The method for manufacturing an electrode sheet according to claim 11, wherein: The positive tab connection area and the negative tab connection area are located on the same side of the electrode sheet.

13. A sodium ion battery, characterized in that: include: The electrode sheet according to any one of claims 1 to 7; The diaphragm covers the front side or the back side of the electrode sheet.

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