Preparation method of pole piece and battery

Abstract

The invention discloses a preparation method of a pole piece and a battery, and aims to overcome the defects of missed coating, non-uniform coating and the like on the edge close to a tab when a solid electrolyte slurry is coated due to a thickness difference in a junction position of an active material and the tab. According to the preparation method of the pole piece, the edges of the two ends of the active material coating are coated with the first solid electrolyte layers in advance, so that the first solid electrolyte layers can bear the edges of the active material coating, and when the active material coating continues to be coated with the second solid electrolyte layer, the first solid electrolyte layers can bear the edges of the active material coating; as the edge of the active material is coated with the first solid electrolyte, the defects of missed coating, non-uniform coating and the like on the edge when the second solid electrolyte is coated can be overcome.

Description

Technical Field

[0001] The present application generally relates to the field of lithium batteries, and specifically to a method for preparing a pole piece and a battery. Background Art

[0002] Lithium batteries have been widely used due to their high energy density and long life. Traditional liquid lithium batteries contain a large amount of electrolyte, which poses a great safety hazard. Therefore, solid electrolytes are generally used instead of electrolytes to solve safety problems. Lithium batteries containing solid electrolytes include tabs, positive electrode active materials, positive electrode current collectors, negative electrode active materials, negative electrode current collectors and solid electrolytes. Tabs are the inactive material coating areas on the current collectors. The traditional method of introducing solid electrolytes into pole pieces is to directly coat the solid electrolyte slurry on the surface of the positive electrode active material. However, when coating the solid electrolyte slurry in this method, due to the thickness difference at the junction of the active material and the tab, defects such as missing coating and uneven coating will occur near the edge of the tab when coating the solid electrolyte slurry. Summary of the invention

[0003] In view of the above-mentioned defects or deficiencies in the prior art, it is desired to provide a method for preparing a pole piece that can overcome the above-mentioned problems.

[0004] A first aspect provides a method for preparing a pole piece, the method comprising: Coating a first solid electrolyte layer on a first region and a second region of a target current collector, wherein the first region and the second region are spaced apart along a width direction of the target current collector, and the first region and the second region extend along a length direction of the target current collector; An active material coating is applied on a third region between the first region and the second region, wherein two boundaries of the active material coating along the width direction of the target current collector both meet the following requirements: exceeding the first boundary of the first region and the first boundary of the second region or being in contact with the first boundary of the first region and the first boundary of the second region, and not exceeding the second boundary of the first region and the second boundary of the second region; the first boundary of the first region is a boundary of the first region close to the second region, and the first boundary of the second region is a boundary of the second region close to the first region; the second boundary of the first region is a boundary of the first region away from the second region, and the second boundary of the second region is a boundary of the second region away from the first region; A second solid electrolyte layer is coated on the active material coating to obtain a target electrode sheet, wherein a boundary of the second solid electrolyte layer in a width direction of the target current collector exceeds a boundary of the active material coating.

[0005] The second aspect provides a battery, comprising a pole piece prepared by the preparation method of the first aspect.

[0006] The present application provides a method for preparing a pole piece and a battery. Considering the thickness difference at the junction of the active material and the pole ear, when applying the solid electrolyte slurry, defects such as missing coating and uneven coating will occur near the edge of the pole ear, which will cause wrinkles to easily form on the edge, resulting in reduced resistance of the pole piece. The preparation method of the present application pre-coats the first solid electrolyte layer on the edges of both ends of the active material coating, so the first solid electrolyte layer can take over the edge of the active material coating. In this way, when the second solid electrolyte layer is continuously coated on the active material coating, since the first solid electrolyte has been coated on the edge of the active material, it is possible to compensate for the defects such as missing coating and uneven coating that occur at the edge when applying the second solid electrolyte, so that the edge of the second solid electrolyte layer is not easy to wrinkle, thereby improving the resistance of the pole piece. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings: Figure 1 A flowchart of the steps of a method for preparing a pole piece provided in the present application; Figure 2 A schematic diagram of the structure of a target pole piece provided in this application; Figure 3 A schematic diagram of the structure of another target pole piece provided in this application; Figure 4 A schematic diagram of the structure of another target pole piece provided in this application; Figure 5 A schematic diagram of the structure of another target pole piece provided in this application; Figure 6 A schematic diagram of the structure of another target pole piece provided in this application; Figure 7 A schematic diagram of the structure of another target pole piece provided in this application; Figure 8 A schematic diagram of the structure of another target pole piece provided in this application; Fig. 9 A schematic diagram of the structure of another target pole piece provided in this application; Fig.10 A schematic diagram of the structure of another target pole piece provided in this application; Fig.11 The battery cycle test results of the embodiments and comparative examples of the present application are shown in FIG. Description of the drawings: 1000, target current collector; 200, tab area; 101, first region; 102, second region; 103, third region; 104, first solid electrolyte layer; 105, active material coating; 106, carbon coating layer; 107, second solid electrolyte layer; 1011. a first boundary of the first region; 1012. a second boundary of the first region; 1021. a first boundary of a second region; 1022. a second boundary of a second region; 1051, a first boundary of the active material coating; 1052, a second boundary of the active material coating; 1061, a first boundary of the carbon-coated layer; 1062, a second boundary of the carbon-coated layer; 1071. A first boundary of a second solid electrolyte layer. 1072. A second boundary of a second solid electrolyte layer. DETAILED DESCRIPTION

[0009] The present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It is also necessary to explain that, for ease of description, only the parts related to the invention are shown in the accompanying drawings.

[0010] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0011] The existing method of preparing an electrode by coating a solid electrolyte layer on an active material layer will easily cause wrinkles due to the thickness difference of the electrode at the junction of the active material and the electrode ear, resulting in defects such as missing coating and uneven coating when coating the solid electrolyte layer.

[0012] In view of the above problems, this application provides a new method for preparing a pole piece, please refer to Figure 1 , the method comprises the following steps: Step S20, coating the first solid electrolyte layer 104 on the first region 101 and the second region 102 of the target current collector 1000, wherein the first region 101 and the second region 102 are spaced apart along the width direction of the target current collector 1000, and the first region 101 and the second region 102 extend along the length direction of the target current collector 1000; The solid electrolyte layer is used to separate the positive electrode material and the negative electrode material in the battery and to exchange ions between the positive electrode material and the negative electrode material. Compared with the electrolyte in the traditional liquid lithium-ion battery, the solid electrolyte layer will not burn or leak, and has a higher ionic conductivity, so it can not only improve the safety of the battery, but also help to increase the energy density and charging speed of the battery.

[0013] The target current collector 1000 may be any current collector used to make a battery. The target current collector 1000 may be a copper foil or an aluminum foil. The preparation methods of copper foil and aluminum foil are the same. The embodiment of the present application does not limit the material of the target current collector.

[0014] The target current collector 1000 may be a rectangular structure. The width dimension of the tab region 200 of the target current collector 1000 is set according to production requirements and is not limited here.

[0015] The area between the tab regions 200 is used for coating the active material coating 105 and the solid electrolyte layer to obtain the target pole piece required for producing the battery.

[0016] It should be noted that the target current collector 1000 can be coated on one side or on both sides, and the coating methods can be the same or different. The embodiment of the present application only takes coating one side of the target current collector 1000 as an example for description.

[0017] Generally, the target current collector 1000 is in the shape of a strip with a certain length. After coating, multiple target pole pieces can be obtained by cutting to manufacture batteries, which can improve the production efficiency of the pole pieces.

[0018] Below with the help of Figure 2 For explanation, before coating the area between the tab areas 200 of the target current collector 1000 in the embodiment of the present application, reference areas for coating the active material and coating the solid electrolyte may be determined first, namely the first area 101 and the second area 102 mentioned above. The first area 101 and the second area 102 are two areas spaced apart along the width direction of the target current collector 1000. Preferably, the first area 101 and the second area 102 may be arranged in parallel.

[0019] Optionally, for an entire wider target current collector 1000 , the first region 101 and the second region 102 may be arranged in a cycle, so that a plurality of target pole pieces with the same structure may be obtained when the target current collector 1000 is cut along its width direction.

[0020] Optionally, the first region 101 and the second region 102 may be of the same shape or of different shapes. For example, the first region 101 and the second region 102 may both be rectangular structures. The sizes of the first region 101 and the second region 102 may be the same or different, and may be set according to production needs, which will not be described in detail here. For example, the sizes of the first region 101 and the second region 102 along the width direction of the target current collector 1000 may be set between 1-50 mm.

[0021] It is understandable that when the target current collector 1000 has a certain length and the extension of the first region 101 and the second region 102 along the length direction of the target current collector 1000 is limited, the first region 101 and the second region 102 can also be arranged cyclically along the length direction of the target current collector 1000.

[0022] After the first region 101 and the second region 102 on the target current collector 1000 are determined, solid electrolyte coating can be performed on the first region 101 and the second region 102, respectively, to obtain the first solid electrolyte layer 104. The thickness of the first solid electrolyte layer 104 coated on the first region 101 and the second region 102 can be the same or different. Preferably, the thickness of the first solid electrolyte layer 104 coated on the first region 101 and the second region 102 is the same, so that it is easier to operate when the active material coating 105 is subsequently coated based on the first region 101 and the second region 102, and the coating appearance of the active material coating 105 is also smoother. In addition, a neat plane can be provided for coating the second solid electrolyte layer 107, avoiding the occurrence of coating gaps, thereby obtaining a target electrode with better performance.

[0023] Optionally, the thickness of the first solid electrolyte layer 104 on the first region 101 and the thickness of the first solid electrolyte layer 104 on the second region 102 may be set between 1 μm and 100 μm.

[0024] Step S30, coating an active material coating 105 on the third region 103 between the first region 101 and the second region 102; Among them, in the embodiment of the present application, an active material coating 105 is coated on the target current collector 1000. With the help of the active material coating 105, the solid electrolyte layer can be more closely attached to the surface of the current collector to obtain a target electrode with better performance.

[0025] Figure 3 This is a possible coating method of the active material coating 105 provided in the embodiment of the present application. Figure 3, the boundary of the active material coating 105 along the width direction of the target current collector 1000 exceeds the first boundary 1011 of the first region and the first boundary 1021 of the second region, and does not exceed the second boundary 1012 of the first region and the second boundary 1022 of the second region. In other words, the active material coating 105 along the width direction of the target current collector 1000 may have a greater width than the third region 103, or the active material coating 105 has exactly the same width as the third region 103; so that along the width direction of the target current collector 1000, the two boundaries of the active material coating 105 may be located inside the first region 101 and the second region 102, respectively, or the active material coating 105 is exactly in contact with the first region 101 and the second region 102.

[0026] Figure 4 This is another possible coating method of the active material coating 105 provided in the embodiment of the present application. Figure 4 The boundary of the active material coating 105 along the width direction of the target current collector 1000 is connected to the first boundary 1011 of the first region and the first boundary 1021 of the second region, and does not exceed the second boundary 1012 of the first region and the second boundary 1022 of the second region.

[0027] refer to Figure 3 or Figure 4 The first boundary 1011 of the first area is the boundary of the first area 101 close to the second area 102, and the first boundary 1021 of the second area is the boundary of the second area 102 close to the first area 101; the second boundary 1012 of the first area is the boundary of the first area 101 away from the second area 102, and the second boundary 1022 of the second area is the boundary of the second area 102 away from the first area 101.

[0028] In the embodiment of the present application, after the first solid electrolyte layer 104 is coated on the first region 101 and the second region 102, the active material coating 105 is coated on the third region 103 between the first region 101 and the second region 102. In this way, during the process of coating the active material coating 105 on the third region 103, it can be ensured that the boundary of the active material layer 105 along the width direction of the target current collector 1000 exceeds the first boundary 1011 of the first region and the first boundary 1021 of the second region, and does not exceed the second boundary 1012 of the first region and the second boundary 1022 of the second region, or it can be ensured that the boundary of the active material layer 105 along the width direction of the target current collector 1000 is connected to the first boundary 1011 of the first region and the first boundary 1021 of the second region, so that after the first solid electrolyte layer 104 and the active material coating 105 are coated, the empty foil at the junction of the first solid electrolyte layer 104 and the active material coating 105 is avoided, thereby improving the coating quality and product yield of the electrode sheet.

[0029] In a preferred embodiment, the present application may be selected as follows Figure 4 The coating method shown is to coat the active material coating 105 on the third region 103, that is, the boundary of the active material layer 105 along the width direction of the target current collector 1000 is connected with the first boundary 1011 of the first region and the first boundary 1021 of the second region. On the one hand, it can better avoid the occurrence of empty foil at the edge of the active material coating 105 104 and the edge of the second solid electrolyte layer 107, thereby causing defects such as missing coating and uneven coating, making it less likely for the edge of the solid electrolyte layer to wrinkle, thereby improving the resistance of the electrode sheet. On the other hand, it can also avoid the waste of active materials and reduce the amount of the second solid electrolyte.

[0030] Step S40 , coating the second solid electrolyte layer 107 on the active material coating layer 105 , wherein the boundary of the second solid electrolyte layer 107 in the width direction of the target current collector 1000 exceeds the boundary of the active material coating layer 105 .

[0031] The raw materials required for preparing the second solid electrolyte layer 107 and the first solid electrolyte layer 104 may be the same or different. In the coating scheme provided in the embodiment of the present application, the first solid electrolyte layer 104 is coated first, and the second solid electrolyte layer 107 is coated later, but in the end, the first solid electrolyte layer 104 and the second solid electrolyte layer 107 will play the same role in the battery as a whole, both of which are to isolate the positive electrode material and the negative electrode material in the battery, and to perform ion exchange between the positive electrode material and the negative electrode material.

[0032] In some other embodiments, the active material coating 105 is a coating method in which the boundary along the width direction of the target current collector 1000 exceeds the first boundary 1011 of the first region and the first boundary 1021 of the second region, but does not exceed the second boundary 1012 of the first region and the second boundary 1022 of the second region as an example of a possible coating method of the second solid electrolyte layer 107. Figure 5 , the first boundary 1071 of the second solid electrolyte layer exceeds the first boundary 1051 of the active material coating, the second boundary 1072 of the second solid electrolyte layer exceeds the second boundary 1052 of the active material coating, the first boundary 1071 of the second solid electrolyte layer does not exceed the second boundary 1012 of the first region, and the second boundary 1072 of the second solid electrolyte layer does not exceed the second boundary 1022 of the second region. In other words, along the width direction of the target current collector, the width of the second solid electrolyte layer 107 is greater than the width of the active material coating, and the second solid electrolyte layer 107 covers the active material coating, so that the two boundaries of the second solid electrolyte layer can be farther away from the third region than the two boundaries of the active material coating 105.

[0033] remove Figure 5 In addition to the coating method, the present embodiment also provides another possible coating method of the second solid electrolyte layer 107. Figure 6 , a first boundary 1071 of the second solid electrolyte layer is flush with a second boundary 1012 of the first region, and a second boundary 1072 of the second solid electrolyte layer is flush with a second boundary 1022 of the second region 102 .

[0034] Of course, there are other possible coating methods for the second solid electrolyte layer 107 , as long as the two boundaries of the second solid electrolyte layer 107 exceed the boundary of the active material coating 105 , which are not listed here one by one.

[0035] The existing technology is to apply an active material coating on the current collector, and then apply a solid electrolyte layer on the active material coating. When the solid electrolyte layer is coated on the active material coating, there is a thickness difference between the edge pole ear area and the active material area, resulting in defects such as missing coating and uneven coating at the edge of the solid electrolyte layer during coating, which makes it easy for wrinkles to form on the edge, resulting in reduced resistance of the pole piece.

[0036] In the coating scheme provided in the embodiment of the present application, the first solid electrolyte layer 104 is first coated on the first region 101 and the second region 102, and then the active material coating 105 is coated on the third region 103 between the first region 101 and the second region 102, and finally a second solid electrolyte layer 107 is coated on the active material coating 105, but when the active material coating 105 is coated, its boundary along the width direction of the target current collector 1000 does not exceed the outer boundary of the first region 101 and the second region 102 (i.e., the second boundary 1012 of the first region and the second boundary 1022 of the second region). Since the first solid electrolyte layer 104 is pre-coated before the active material coating 105 is coated, the first solid electrolyte layer 104 takes over the edge of the active material coating 105, so when the second solid electrolyte layer 107 is continuously coated on the active material coating 105, since the first solid electrolyte layer 104 has been pre-coated on the edge of the active material coating 105, the problem of missing coating and uneven coating at the edge when the second solid electrolyte layer 107 is coated can be compensated.

[0037] In another embodiment provided in the present application, reference Figure 7 , Figure 7 It is a possible coating thickness of the first solid electrolyte layer 104 and the active material coating 105 provided in the embodiment of the present application. The coating thickness of the first solid electrolyte layer 104 is the same as the coating thickness D of the active material coating 105 .

[0038] Coating the first solid electrolyte layer 104 and the active material coating 105 to the same thickness can make the first solid electrolyte layer 104 and the active material coating 105 located on the same plane, providing a better coating environment for the subsequent coating of the second solid electrolyte layer 107, reducing the leveling space of the second solid electrolyte layer 107, improving the operability of coating the second solid electrolyte layer 107, and further improving the coating efficiency. At the same time, it is also helpful to solve the defects of the active material coating 105 such as missing edges and uneven coating, so that the edges of the second solid electrolyte layer 107 are not easy to wrinkle, thereby improving the resistance of the electrode.

[0039] In another embodiment provided in the present application, reference Figure 8 , Figure 8 It is another possible coating thickness of the first solid electrolyte layer 104 and the active material coating 105 provided in the embodiment of the present application. Among them, the thickness of the coated first solid electrolyte layer 104 is less than the thickness of the coated active material coating 105, that is, there is a thickness difference d between the thickness of the first solid electrolyte layer 104 and the thickness of the active material coating 105. The embodiment is conducive to reliably coating the second solid electrolyte layer in the third area during the actual processing, avoiding the formation of the second solid electrolyte layer in the third area.

[0040] In another embodiment provided in the present application, the embodiment of the present application may be coated with a carbon coating layer 106 before coating the active material coating layer 105. That is, in one embodiment of the present application, after coating the first solid electrolyte layer 104 on the first region 101 and the second region 102, a carbon coating layer 106 is coated on the third region 103 between the first region 101 and the second region 102, and then an active material coating layer 105 is coated on the carbon coating layer 106. Alternatively, the first region 101, the second region 102, and the third region 103 on the target current collector 1000 are zoned for coating at the same time, the first solid electrolyte layer 104 is coated on the first region 101 and the second region 102, the carbon coating layer 106 is coated on the third region 103, and then an active material coating layer 105 is coated on the carbon coating layer 106.

[0041] The purpose of setting the carbon coating layer 106 in the embodiment of the present application is to further improve the adhesion between the active material coating 105 and the surface of the target current collector 1000, reduce the internal resistance of the battery, increase the cycle life of the battery, enhance the consistency of the battery, improve the rate performance and protect the target current collector 1000 from being corroded by the electrolyte.

[0042] Optionally, refer to Fig. 9 , Fig. 9This is a possible coating method of the active material coating 105 and the carbon coating layer 106 provided in an embodiment of the present application. The boundary of the active material coating 105 exceeds the boundary of the carbon coating layer 106, and the difference between the boundary of the active material coating 105 along the width direction of the target current collector 1000 and the boundary of the carbon coating layer 106 along the length direction of the target current collector 1000 is between 0-1 mm.

[0043] Continue to refer Fig. 9 The active material coating 105 includes a first boundary 1051 of the active material coating and a second boundary 1052 of the active material coating, wherein the first boundary 1051 of the active material coating may be a boundary close to the first region 101 , and the second boundary 1052 of the active material coating may be a boundary close to the second region 102 .

[0044] The carbon-coated layer 106 includes a first boundary 1061 of the carbon-coated layer and a second boundary 1062 of the carbon-coated layer, wherein the first boundary 1061 of the carbon-coated layer may be a boundary close to the first region 101 , and the second boundary 1062 of the carbon-coated layer may be a boundary close to the second region 102 .

[0045] The boundary of the active material coating 105 exceeds the boundary of the carbon coating 106 specifically includes: the first boundary 1051 of the active material coating exceeds the first boundary 1061 of the carbon coating, and the distance between the first boundary 1051 of the active material coating and the first boundary 1061 of the carbon coating is between 0-1 mm.

[0046] Furthermore, the second boundary 1052 of the active material coating layer exceeds the second boundary 1062 of the carbon coating layer, and the distance between the second boundary 1052 of the active material coating layer and the second boundary 1062 of the carbon coating layer is between 0-1 mm.

[0047] refer to Fig.10 , Fig.10 This is another possible coating method of the active material coating 105 and the carbon coating layer 106 provided in the embodiment of the present application. The boundary of the active material coating 105 is flush with the boundary of the carbon coating layer 106, that is, the coating effect is presented when the difference between the boundary of the active material coating 105 along the width direction of the target current collector 1000 and the boundary of the carbon coating layer 106 along the length direction of the target current collector 1000 is 0.

[0048] It should be noted here that the relationship between the carbon coating layer 106 and each boundary of the first region 101 and the second region 102 is the same as the relationship between the active material coating layer 105 and each boundary of the first region 101 and the second region 102. Optionally, both boundaries of the carbon coating layer 106 along the width direction of the target current collector satisfy: exceeding the first boundary 1011 of the first region and the first boundary 1021 of the second region or connecting with the first boundary 1011 of the first region and the first boundary 1021 of the second region, and not exceeding the second boundary 1021 of the first region and the second boundary 1022 of the second region.

[0049] Optionally, the first solid electrolyte layer 104 may be coated on the first region 101 and the second region 102 by at least one coating method such as micro-concave roller coating, gravure roller coating, dispensing coating, spraying, etc. When the first solid electrolyte layer 104 is coated on the first region 101 and the second region 102, the coating area of ​​the first solid electrolyte layer 104 may be equal to the sum of the areas of the first region 101 and the second region 102, so that there will be no missing coating or uneven coating.

[0050] Optionally, the present application may adopt a slot extrusion coating method to coat the active material coating 105 . Such a coating method matches the location of the active material coating 105 , so a better coating effect can be obtained.

[0051] Optionally, the carbon coating layer 106 may be coated by gravure coating or micro-concave coating.

[0052] Optionally, the second solid electrolyte layer 107 may be coated by at least one of micro-concave roller coating, gravure roller coating, dispensing coating, and spray coating. Exemplarily, the coating thickness of the second solid electrolyte layer 107 is 1-100 μm.

[0053] Optionally, in the embodiment of the present application, after the first solid electrolyte layer 104 and the active material coating 105 are coated, a roller pressing process is performed, so that the protrusions on the surface of the first solid electrolyte layer 104 and the active material coating 105 can be flattened to reduce the subsequent infiltration of the second solid electrolyte layer 107. In addition, after the roller pressing process, when the second solid electrolyte layer 107 is coated, the coating thickness of the second solid electrolyte layer 107 can be reduced, for example, the coating thickness of the second solid electrolyte layer 107 is set between 1-10 μm, which can not only save materials, but also manufacture thinner batteries to adapt to more usage scenarios.

[0054] Optionally, the embodiment of the present application can also perform a rolling process after the first solid electrolyte layer 104 is coated, and also perform a rolling process after the active material coating layer 105 is coated, that is, a rolling process is performed once a layer of coating is completed. In this way, each coated layer can present a good shape, and a better coating environment can be provided for subsequent coating, thereby improving the qualified rate of the production of pole pieces.

[0055] Optionally, the embodiment of the present application can also perform an overall rolling process after the coating of the second solid electrolyte layer 107 is completed, which can reduce the preparation process and improve the efficiency of the preparation. It can be understood that in this case, in order to avoid exposure of the active material coating 105, when the second solid electrolyte layer 107 is coated, the coating thickness of the second solid electrolyte layer 107 can be increased.

[0056] The present application provides a method for preparing a pole piece. Considering the thickness difference at the junction of the active material and the pole ear, when applying the solid electrolyte slurry, defects such as missing coating and uneven coating will occur near the edge of the pole ear. The present application provides a method for preparing a pole piece. The preparation method pre-coats a first solid electrolyte layer on the edges of both ends of the active material coating, so that the first solid electrolyte layer can take over the edge of the active material coating, so that when the second solid electrolyte layer is continuously coated on the active material coating, since the first solid electrolyte has been coated on the edge of the active material, the defects such as missing coating and uneven coating that occur at the edge when applying the second solid electrolyte can be compensated.

[0057] In another embodiment, the present application also provides a battery, which includes a target pole piece obtained by the above method. Compared with the solution of directly introducing solid electrolyte on the pole piece, during the manufacturing and testing process of the diaphragm-free battery, the qualified rate increased from 80% to 90%, a full 10% increase, which is mainly reflected in the improvement of the short-circuit rate index. Experiments have shown that the battery of the present application can effectively reduce the occurrence of short-circuit rate and has a high product yield.

[0058] Example 1 1. Preparation of negative electrode sheet The negative electrode active material graphite, the binder SBR, and the conductive agent SP are mixed in a mass ratio of 8:1:1 to obtain a mixed material, and the mixed material is fully stirred in deionized water to obtain a corresponding negative electrode slurry; Coating a first solid electrolyte (LLZO) on a first region and a second region on both sides of the negative electrode current collector copper foil, and drying to obtain a first negative electrode sheet; The negative electrode slurry is evenly coated on the third area of ​​the first negative electrode plate to obtain a thickness of 350 μm and a surface density of 0.023 g / cm 2A negative electrode active material layer is formed to obtain a negative electrode second electrode sheet; A 2 μm thick second solid electrolyte (LLZO) is coated on the negative electrode second pole piece (the first region, the second region and the third region) by micro-gravure roller coating, and the final negative electrode pole piece is obtained after drying, rolling and slicing.

[0059] 2. Preparation of positive electrode The positive electrode active material NMC622, the binder PVDF, and the conductive agent SP are mixed in a mass ratio of 8:1:1 to obtain a mixed material, and the mixed material is fully stirred in NMP to obtain a corresponding positive electrode slurry; Coating a first solid electrolyte (LATP) on the first and second regions of both sides of the positive electrode current collector aluminum foil, and drying to obtain a first positive electrode sheet; The positive electrode slurry is evenly coated on the third area of ​​the first positive electrode plate to obtain a positive electrode slurry with a thickness of 280 μm and a surface density of 0.041 g / cm 2 A positive electrode active material layer is formed to obtain a positive electrode second electrode sheet; A layer of 2 μm thick second solid electrolyte (LATP) is coated on the positive electrode second pole piece (first region, second region and third region) by micro-gravure roller, and the final positive electrode pole piece is obtained after drying, rolling and slicing.

[0060] 3. Lithium battery assembly The negative electrode sheet and the positive electrode sheet prepared above are stacked on each other to obtain a battery cell (a battery cell without a diaphragm), and the battery cell is filled with an aluminum-plastic film, dried, injected with electrolyte, packaged, formed, and divided into different capacities to obtain a lithium-ion battery.

[0061] Example 2 The difference between this embodiment and embodiment 1 is that in this embodiment, in the preparation of the negative electrode sheet, the first solid electrolyte is LLZTO, and the second solid electrolyte is LLZTO; During the preparation of the positive electrode sheet, the first solid electrolyte is LiP3S4 and the second solid electrolyte is LATP.

[0062] Example 3 The difference between this embodiment and embodiment 1 is that in this embodiment, during the preparation of the positive electrode sheet, the first solid electrolyte is Li7P3S 11 The second solid electrolyte is Li7P3S 11 .

[0063] Example 4 The difference between this embodiment and embodiment 1 is that in this embodiment, in the preparation of the negative electrode sheet, the first solid electrolyte is LLZTO, and the second solid electrolyte is LLZTO; During the preparation of the positive electrode sheet, the first solid electrolyte is Li7P3S 11 The second solid electrolyte is Li7P3S 11 .

[0064] Comparative Example 1 The negative electrode active material graphite, the binder SBR, and the conductive agent SP are mixed in a mass ratio of 8:1:1 to obtain a mixed material, and the mixed material is fully stirred in deionized water to obtain a corresponding negative electrode slurry; The negative electrode slurry was uniformly coated on the third area of ​​both sides of the negative electrode current collector copper foil to obtain a negative electrode slurry with a thickness of 350 μm and a surface density of 0.023 g / cm 2 A negative electrode active material layer is formed to obtain a negative electrode first electrode sheet; A 2 μm thick second solid electrolyte (LLZO) is coated on the first negative electrode sheet (first region, second region and third region) by micro-gravure roller coating, and the final negative electrode sheet is obtained after drying, rolling and slicing.

[0065] 2. Preparation of positive electrode The positive electrode active material NMC622, the binder PVDF, and the conductive agent SP are mixed in a mass ratio of 8:1:1 to obtain a mixed material, and the mixed material is fully stirred in NMP to obtain a corresponding positive electrode slurry; The positive electrode slurry was evenly coated on the third area of ​​both sides of the positive electrode current collector aluminum foil to obtain a positive electrode with a thickness of 280 μm and a surface density of 0.041 g / cm 2 A positive electrode active material layer is formed to obtain a positive electrode first pole piece; A 2 μm thick second solid electrolyte (LATP) is coated on the first positive electrode sheet (first region, second region and third region) by micro-gravure roller coating, and the final positive electrode sheet is obtained after drying, rolling and slicing.

[0066] 3. Lithium battery assembly The negative electrode sheet and the positive electrode sheet prepared above are stacked on each other to obtain a battery cell (a battery cell without a diaphragm), and the battery cell is filled with an aluminum-plastic film, dried, injected with electrolyte, packaged, formed, and divided into different capacities to obtain a lithium-ion battery.

[0067] The batteries of the above-mentioned Examples 1-4 and Comparative Example 1 were subjected to a battery cycle performance test. The test process was as follows: charging and discharging at a current density of 0.1C, after two cycles of activation, charging and discharging at a current density of 0.2C for 70 cycles. The test results are as follows: Fig.11 shown.

[0068] according to Fig.11It can be seen from the test results shown that the discharge specific capacity of the batteries of Examples 1-4 after the cycle test is better than that of the battery of Comparative Example 1, which shows that the electrode preparation method of the present application is conducive to uniform distribution of the electrode coating, thereby making the battery have good cycle performance.

[0069] It should be noted that although the operations of the method of the present invention are described in a specific order in the accompanying drawings, this does not require or imply that these operations must be performed in this specific order, or that all the operations shown must be performed to achieve the desired results. On the contrary, the steps depicted in the flow chart can change the execution order.

[0070] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with (but not limited to) technical features with similar functions disclosed in the present application.

Claims

1. A method for preparing a pole piece, characterized in that: The method comprises: Coating a first solid electrolyte layer on a first region and a second region of a target current collector, wherein the first region and the second region are spaced apart along a width direction of the target current collector, and the first region and the second region extend along a length direction of the target current collector; An active material coating is applied on a third region between the first region and the second region, wherein two boundaries of the active material coating along the width direction of the target current collector both meet the following requirements: exceeding the first boundary of the first region and the first boundary of the second region or being in contact with the first boundary of the first region and the first boundary of the second region, and not exceeding the second boundary of the first region and the second boundary of the second region; the first boundary of the first region is a boundary of the first region close to the second region, and the first boundary of the second region is a boundary of the second region close to the first region; the second boundary of the first region is a boundary of the first region away from the second region, and the second boundary of the second region is a boundary of the second region away from the first region; A second solid electrolyte layer is coated on the active material coating to obtain a target electrode sheet, wherein two boundaries of the second solid electrolyte layer in the width direction of the target current collector exceed the boundary of the active material coating.

2. The preparation method according to claim 1, characterized in that: The thickness of the active material coating layer is greater than or equal to the thickness of the first solid electrolyte layer.

3. The preparation method according to claim 1, characterized in that: The thickness of the first solid electrolyte layer on the first region is the same as the thickness of the first solid electrolyte layer on the second region.

4. The preparation method according to claim 1, characterized in that: Both boundaries of the second solid electrolyte layer along the width direction of the target current collector satisfy: exceeding a first boundary of the first region and a first boundary of the second region, and not exceeding a second boundary of the first region and a second boundary of the second region.

5. The preparation method according to claim 4, characterized in that: A first boundary of the second solid electrolyte layer along the width direction of the target current collector is flush with a second boundary of the first region, and a second boundary of the second solid electrolyte layer along the width direction of the target current collector is flush with a second boundary of the second region.

6. The preparation method according to claim 1, characterized in that: The method further comprises: Before applying the active material coating, a carbon coating layer is applied on the third region.

7. The preparation method according to claim 1, characterized in that: The method further comprises: After coating the second solid electrolyte layer on the active material coating layer, the target current collector is roll-pressed.

8. The preparation method according to claim 1, characterized in that: The first solid electrolyte layer and the second solid electrolyte layer include at least one of an oxide solid electrolyte, a sulfide solid electrolyte, a halide solid electrolyte, and a polymer solid electrolyte.

9. The preparation method according to claim 1, characterized in that: The first solid electrolyte layer and the second solid electrolyte layer are coated by at least one method selected from micro-concave roller coating, gravure roller coating, dispensing coating, and spray coating.

10. The preparation method according to claim 1, characterized in that: The coating thickness of the first solid electrolyte layer is between 1 μm and 100 μm.

11. The preparation method according to claim 6, characterized in that: The active material coating layer covers the carbon coating layer, and a difference between a boundary of the active material coating layer along the width direction of the target current collector and a boundary of the carbon coating layer along the width direction of the target current collector is between 0 and 1 mm.

12. The preparation method according to claim 11, characterized in that: The carbon coating layer is coated by gravure coating or micro-gravure coating technology, and the active material coating is coated by slot extrusion technology.

13. The preparation method according to claim 1, characterized in that: The method further comprises: After coating the active material coating, the target current collector is roll-pressed.

14. A battery, characterized in that: It comprises a pole piece prepared by the preparation method according to any one of claims 1 to 13.

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