Method for manufacturing an electrode sheet and battery

Abstract

The application discloses a preparation method of an electrode sheet and a battery. Considering that there is a thickness difference at the position where the active material and the tab meet, when coating a solid electrolyte slurry, defects such as missing coating and uneven coating can occur near the edge of the tab. The application provides a preparation method of an electrode sheet, which pre-coats a first solid electrolyte layer on the edges at both ends of the active material coating layer, so that the first solid electrolyte layer can receive the edges of the active material coating layer, and when the second solid electrolyte layer is continuously coated on the active material coating layer, the missing coating and uneven coating defects that occur at the edges when the second solid electrolyte is coated can be compensated for because the first solid electrolyte has been coated at the edges of the active material.

Description

TECHNICAL FIELD

[0001] The present application generally relates to the field of lithium batteries, and in particular to a method for preparing an electrode sheet and a battery. BACKGROUND

[0002] Lithium batteries have been widely used due to their high energy density and long service life. Traditional liquid lithium batteries contain a large amount of electrolyte, which has a great safety hazard. Therefore, solid electrolyte is generally used to replace electrolyte to solve the safety problem.

[0003] A lithium battery containing a solid electrolyte includes a tab, a positive active material, a positive current collector, a negative active material, a negative current collector, and a solid electrolyte. The tab is a non-active material coating area on the current collector. The traditional method for introducing a solid electrolyte on an electrode sheet is to coat a solid electrolyte slurry on the surface of the positive active material. However, when the solid electrolyte slurry is coated, defects such as missing coating and uneven coating occur at the edge close to the tab due to the difference in thickness at the junction between the active material and the tab. SUMMARY

[0004] In view of the above-mentioned defects or shortcomings in the prior art, it is desirable to provide a method for preparing an electrode sheet, which can overcome the above-mentioned problems.

[0005] The first aspect provides a method for preparing an electrode sheet, which comprises:

[0006] coating a first solid electrolyte layer on a first region and a second region of a target current collector, the first region and the second region being arranged at intervals along the width direction of the target current collector, and the first region and the second region extending along the length direction of the target current collector;

[0007] coating an active material coating layer on a third region between the first region and the second region, the active material coating layer satisfying the following conditions along the two boundaries in the width direction of the target current collector: 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 the boundary of the first region close to the second region, the first boundary of the second region is the boundary of the second region close to the first region, the second boundary of the first region is the boundary of the first region away from the second region, and the second boundary of the second region is the boundary of the second region away from the first region;

[0008] A second solid-state electrolyte layer is coated on the active material coating layer to obtain a target electrode sheet, and a boundary of the second solid-state electrolyte layer in the target current collector width direction exceeds a boundary of the active material coating layer.

[0009] The second aspect provides a battery comprising the electrode sheet prepared by the preparation method of the first aspect.

[0010] The application provides a preparation method of an electrode sheet and a battery. Considering that there is a thickness difference at a position where an active material and a tab meet, when a solid-state electrolyte slurry is coated, an edge close to the tab will have defects such as missing coating and uneven coating, thereby causing the edge to be prone to wrinkles and reducing the resistance of the electrode sheet. The preparation method of the application pre-coats a first solid-state electrolyte layer on edges at both ends of an active material coating layer, so that the first solid-state electrolyte layer can receive the edges of the active material coating layer. Thus, when a second solid-state electrolyte layer is continuously coated on the active material coating layer, since the first solid-state electrolyte has been coated on the edge of the active material, the defects such as missing coating and uneven coating that occur on the edge when the second solid-state electrolyte is coated can be compensated for, so that the edge of the second solid-state electrolyte layer is not prone to wrinkles, and the resistance of the electrode sheet is improved. BRIEF DESCRIPTION OF DRAWINGS

[0011] Other features, objects, and advantages of the application will become more apparent from the following detailed description of non-limiting embodiments made with reference to the following drawings:

[0012] Figure 1 A step flow chart of the preparation method of the electrode sheet provided by the application;

[0013] Figure 2 A structure schematic diagram of the target electrode sheet provided by the application;

[0014] Figure 3 A structure schematic diagram of another target electrode sheet provided by the application;

[0015] Figure 4 A structure schematic diagram of another target electrode sheet provided by the application;

[0016] Figure 5 A structure schematic diagram of another target electrode sheet provided by the application;

[0017] Figure 6 A structure schematic diagram of another target electrode sheet provided by the application;

[0018] Figure 7 A structure schematic diagram of another target electrode sheet provided by the application;

[0019] Figure 8 A structure schematic diagram of another target electrode sheet provided by the application;

[0020] Figure 9 A structure diagram of another target pole piece provided in the present application is shown in the following figure;

[0021] Figure 10 A structure diagram of another target pole piece provided in the present application is shown in the following figure;

[0022] Figure 11 The battery cycle test results of the examples and comparative examples of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0024] 1000, target current collector; 200, tab area;

[0025] 101, first area; 102, second area; 103, third area; 104, first solid-state electrolyte layer; 105, active material coating layer; 106, carbon coating layer; 107, second solid-state electrolyte layer;

[0026] 1011, first boundary of the first area; 1012, second boundary of the first area;

[0027] 1021, first boundary of the second area; 1022, second boundary of the second area;

[0028] 1051, first boundary of the active material coating layer; 1052, second boundary of the active material coating layer;

[0029] 1061, first boundary of the carbon coating layer; 1062, second boundary of the carbon coating layer;

[0030] 1071, first boundary of the second solid-state electrolyte layer; 1072, second boundary of the second solid-state electrolyte layer. DETAILED DESCRIPTION

[0031] The present application will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific examples described herein are intended to be illustrative only and are not to be limiting of the application. Additionally, it should be understood that in the drawings, like reference numerals are used to represent like parts throughout the various views.

[0032] It should be understood that the examples and features of the examples in the present application can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and examples.

[0033] The existing method of coating a solid-state electrolyte layer on an active material layer to prepare a pole piece can cause wrinkles due to the thickness difference of the pole piece at the position where the active material and the tab meet, resulting in defects such as missing coating and uneven coating when coating the solid-state electrolyte layer.

[0034] To solve the above problems, the application provides a new preparation method of an electrode sheet, please refer to Figure 1 The method comprises the following steps:

[0035] Step S20, coating a first solid electrolyte layer 104 on the first region 101 and the second region 102 of the target current collector 1000, the first region 101 and the second region 102 are arranged at intervals 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;

[0036] The solid electrolyte layer is used to isolate the positive electrode material and the negative electrode material in the battery, and exchange ions between the positive electrode material and the negative electrode material. Compared with the electrolyte in the traditional lithium ion battery, the solid electrolyte layer will not burn and will not leak, and has higher ionic conductivity, so it can not only improve the safety of the battery, but also help to improve the energy density and the charging speed of the battery.

[0037] The target current collector 1000 can be any current collector used to make a battery. The target current collector 1000 can be a copper foil or an aluminum foil. The preparation methods of the copper foil and the aluminum foil are the same, and the material of the target current collector is not limited in the application.

[0038] The target current collector 1000 can have a rectangular structure. The size of the tab region 200 of the target current collector 1000 along the width direction is set according to the production needs, which is not limited herein.

[0039] The regions between the tab regions 200 are used for coating the active material coating 105 and the solid electrolyte layer, so as to obtain the target electrode sheet required for producing the battery.

[0040] It should be noted that the target current collector 1000 can be coated on one side or both sides, and the coating methods can be the same or different. The application only takes one side of the target current collector 1000 as an example for description.

[0041] Generally, the target current collector 1000 has a length of a long strip. After coating, the target current collector 1000 can be cut into multiple target electrode sheets for producing the battery, so as to improve the production efficiency of the electrode sheet.

[0042] The following will be described with the aid of Figure 2For explanation, before coating the area of ​​the target current collector 1000 between the tab areas 200, the embodiment of the present application may first determine the reference areas for coating the active material and the solid electrolyte, 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.

[0043] Optionally, for an entire wider target current collector 1000 , the first region 101 and the second region 102 may be arranged in a circular manner, 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.

[0044] Optionally, the first region 101 and the second region 102 may have the same or different shapes. For example, the first region 101 and the second region 102 may both have rectangular structures. The first region 101 and the second region 102 may have the same or different sizes, depending on production needs and not described in detail here. For example, the first region 101 and the second region 102 may have a width dimension between 1 and 50 mm along the width of the target current collector 1000.

[0045] 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.

[0046] After determining the first region 101 and the second region 102 on the target current collector 1000, solid electrolyte coating can be performed on the first region 101 and the second region 102, respectively, to obtain a 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 surface 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.

[0047] 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.

[0048] Step S30, coating the active material coating 105 on the third region 103 between the first region 101 and the second region 102;

[0049] Wherein, the embodiment of the present application coats the active material coating 105 on the target current collector 1000, so that the solid electrolyte layer can be more closely attached to the surface of the current collector by means of the active material coating 105, and a target pole piece with better performance is obtained.

[0050] Figure 3 is a possible coating method of the active material coating 105 provided by the embodiment of the present application. Referring to 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 can have a greater width than the third region 103, or the active material coating 105 exactly has an equal width with the third region 103; so that in the width direction of the target current collector 1000, the two boundaries of the active material coating 105 can be located inside the first region 101 and the second region 102 respectively, or the active material coating 105 exactly coincides with the first region 101 and the second region 102.

[0051] Figure 4 is another possible coating method of the active material coating 105 provided by the embodiment of the present application. Referring to Figure 4 , the boundary of the active material coating 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, and does not exceed the second boundary 1012 of the first region and the second boundary 1022 of the second region.

[0052] Referring to Figure 3 or Figure 4 , the first boundary 1011 of the first region is the boundary of the first region 101 close to the second region 102, and the first boundary 1021 of the second region is the boundary of the second region 102 close to the first region 101; the second boundary 1012 of the first region is the boundary of the first region 101 away from the second region 102, and the second boundary 1022 of the second region is the boundary of the second region 102 away from the first region 101.

[0053] In the embodiment of the present application, after the first solid-state electrolyte layer 104 is coated on the first region 101 and the second region 102, the active material coating layer 105 is coated on the third region 103 between the first region 101 and the second region 102. In this way, during the coating of the active material coating layer 105 on the third region 103, the boundary of the active material layer 105 in the width direction of the target current collector 1000 can exceed the first boundary 1011 of the first region and the first boundary 1021 of the second region, and can not exceed the second boundary 1012 of the first region and the second boundary 1022 of the second region, or the boundary of the active material layer 105 in the width direction of the target current collector 1000 can be connected to the first boundary 1011 of the first region and the first boundary 1021 of the second region. Thus, after the coating of the first solid-state electrolyte layer 104 and the active material coating layer 105 is completed, the empty foil at the joint of the first solid-state electrolyte layer 104 and the active material coating layer 105 is avoided, and the coating quality of the pole piece and the product yield are improved.

[0054] In the preferred embodiment, the coating method of the present application can be as shown in Figure 4 In the preferred embodiment, the coating method of the present application can be as shown in

[0055] In the preferred embodiment, the coating method of the present application can be as shown in

[0056] In the preferred embodiment, the coating method of the present application can be as shown in

[0057] 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 for the second solid electrolyte layer 107. Figure 5 , first boundary 1071 of the second solid electrolyte layer exceeds first boundary 1051 of the active material coating layer, second boundary 1072 of the second solid electrolyte layer exceeds second boundary 1052 of the active material coating layer, first boundary 1071 of the second solid electrolyte layer does not exceed second boundary 1012 of the first region, and second boundary 1072 of the second solid electrolyte layer does not exceed 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 layer, and the second solid electrolyte layer 107 covers the active material coating layer, so that the two boundaries of the second solid electrolyte layer can be further away from the third region than the two boundaries of the active material coating layer 105.

[0058] remove Figure 5 In addition to the coating method, the embodiment of the present application also provides another possible coating method of the second solid electrolyte layer 107. Figure 6 The first boundary 1071 of the second solid electrolyte layer is flush with the second boundary 1012 of the first region, and the second boundary 1072 of the second solid electrolyte layer is flush with the second boundary 1022 of the second region 102 .

[0059] 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.

[0060] 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. Since there is a thickness difference between the edge tab area and the active material area when the solid electrolyte layer is applied on the active material coating, defects such as missing coating and uneven coating will appear on 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 electrode.

[0061] In the coating scheme provided by the embodiments of the present application, the first solid-state electrolyte layer 104 is first coated on the first region 101 and the second region 102, and then the active material coating layer 105 is coated on the third region 103 between the first region 101 and the second region 102, and finally a second solid-state electrolyte layer 107 is coated on the active material coating layer 105, but when the active material coating layer 105 is coated, the boundary of the active material coating layer 105 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-state electrolyte layer 104 is pre-coated before the active material coating layer 105 is coated, the first solid-state electrolyte layer 104 receives the edge of the active material coating layer 105, so when the second solid-state electrolyte layer 107 is continuously coated on the active material coating layer 105, since the first solid-state electrolyte layer 104 has been pre-coated on the edge of the active material coating layer 105, it can compensate for the problems of missing coating and uneven coating that occur at the edge when the second solid-state electrolyte layer 107 is coated.

[0062] In another embodiment provided by the present application, referring to Figure 7 , Figure 7 is a possible coating thickness of the first solid-state electrolyte layer 104 and the active material coating layer 105 provided by the embodiments of the present application. Among them, the thickness of the first solid-state electrolyte layer 104 is the same as the thickness D of the active material coating layer 105.

[0063] Coating the first solid-state electrolyte layer 104 and the active material coating layer 105 to the same thickness can make the first solid-state electrolyte layer 104 and the active material coating layer 105 located in the same plane, providing a better coating environment for subsequent coating of the second solid-state electrolyte layer 107, reducing the leveling space of the second solid-state electrolyte layer 107, improving the operability of coating the second solid-state electrolyte layer 107, further improving the efficiency of coating, and also helping to solve the defects of edge missing coating and uneven coating of the active material coating layer 105, so that the edge of the second solid-state electrolyte layer 107 is not prone to wrinkles, and the resistance of the pole piece is improved.

[0064] In yet another embodiment provided by the present application, referring to Figure 8 , Figure 8 is another possible coating thickness of the first solid-state electrolyte layer 104 and the active material coating layer 105 provided by the embodiments of the present application. Among them, the thickness of the first solid-state electrolyte layer 104 is less than the thickness of the active material coating layer 105, that is, there is a thickness difference d between the thickness of the first solid-state electrolyte layer 104 and the thickness of the active material coating layer 105. The embodiment is beneficial to reliably coat the second solid-state electrolyte layer in the third region in actual processing, avoiding the formation of the second solid-state electrolyte layer in the third region.

[0065] In yet another embodiment provided in the present application, the carbon coating layer 106 can be coated before the active material coating layer 105. That is, in one embodiment of the present application, the first solid electrolyte layer 104 is coated on the first region 101 and the second region 102, then the carbon coating layer 106 is coated on the third region 103 between the first region 101 and the second region 102, and then the 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 partitioned for coating, 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 the active material coating layer 105 is coated on the carbon coating layer 106.

[0066] The purpose of the carbon coating layer 106 provided in the embodiments of the present application is to further improve the adhesion of the active material coating layer 105 to the surface of the target current collector 1000, reduce the internal resistance of the battery, improve the cycle life of the battery, enhance the consistency of the battery, improve the rate capability, and protect the target current collector 1000 from corrosion by the electrolyte.

[0067] Optionally, referring to Figure 9 , Figure 9 is a possible coating method of the active material coating layer 105 and the carbon coating layer 106 provided in the embodiments of the present application. In this method, the boundary of the active material coating layer 105 exceeds the boundary of the carbon coating layer 106, and the difference between the boundary of the active material coating layer 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.

[0068] Continuing to refer to Figure 9 , the active material coating layer 105 includes a first boundary 1051 of the active material coating layer and a second boundary 1052 of the active material coating layer, wherein the first boundary 1051 of the active material coating layer can be the boundary close to the first region 101, and the second boundary 1052 of the active material coating layer can be the boundary close to the second region 102.

[0069] The carbon coating layer 106 includes a first boundary 1061 of the carbon coating layer and a second boundary 1062 of the carbon coating layer, wherein the first boundary 1061 of the carbon coating layer can be the boundary close to the first region 101, and the second boundary 1062 of the carbon coating layer can be the boundary close to the second region 102.

[0070] The boundary of the active material coating 105 exceeding the boundary of the carbon coating layer 106 specifically includes: the first boundary 1051 of the active material coating exceeding the first boundary 1061 of the carbon coating layer, and the distance between the first boundary 1051 of the active material coating and the first boundary 1061 of the carbon coating layer being between 0-1mm.

[0071] In addition, the second boundary 1052 of the active material coating exceeding the second boundary 1062 of the carbon coating layer, and the distance between the second boundary 1052 of the active material coating and the second boundary 1062 of the carbon coating layer being between 0-1mm.

[0072] Reference Figure 10 , Figure 10 The above is another possible coating method of the active material coating 105 and the carbon coating layer 106 provided by the embodiment of the present application. In the coating method, the boundary of the active material coating 105 is flush with the boundary of the carbon coating layer 106, that is, the coating effect 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.

[0073] It should be noted that the relationship between the carbon coating layer 106 and the boundaries of the first region 101 and the second region 102 is the same as the relationship between the active material coating 105 and the boundaries of the first region 101 and the second region 102. Alternatively, both boundaries of the carbon coating layer 106 along the width direction of the target current collector satisfy: exceeding or abutting 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.

[0074] Alternatively, the first solid-state electrolyte layer 104 can 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, and spraying. When the first solid-state electrolyte layer 104 is coated on the first region 101 and the second region 102, the coating area of the first solid-state electrolyte layer 104 can be equal to the sum of the areas of the first region 101 and the second region 102, so as to avoid the situation of missing coating or uneven coating.

[0075] Alternatively, the active material coating 105 can be coated by using a slot extrusion coating method. Such a coating method matches the position of the active material coating 105, so that a better coating effect can be obtained.

[0076] Alternatively, the carbon coating layer 106 can be coated by using a gravure coating method or a micro-concave coating method.

[0077] Optionally, the second solid-state electrolyte layer 107 can be coated by at least one of micro-concave roller coating, gravure roller coating, dispensing coating, and spraying. For example, the coating thickness of the second solid-state electrolyte layer 107 is 1-100 μm.

[0078] Optionally, the first solid-state electrolyte layer 104 and the active material coating layer 105 can be subjected to roller pressing after being coated. In this way, the protrusions on the surface of the first solid-state electrolyte layer 104 and the active material coating layer 105 can be flattened to reduce the subsequent infiltration of the second solid-state electrolyte layer 107. In addition, after the roller pressing, the coating thickness of the second solid-state electrolyte layer 107 can be reduced, for example, the coating thickness of the second solid-state electrolyte layer 107 is set to be between 1-10 μm. In this way, not only the material can be saved, but also a thinner battery can be manufactured to adapt to more use scenarios.

[0079] Optionally, the first solid-state electrolyte layer 104 and the active material coating layer 105 can be subjected to roller pressing after being coated. In this way, the protrusions on the surface of the first solid-state electrolyte layer 104 and the active material coating layer 105 can be flattened to reduce the subsequent infiltration of the second solid-state electrolyte layer 107. In addition, after the roller pressing, the coating thickness of the second solid-state electrolyte layer 107 can be reduced, for example, the coating thickness of the second solid-state electrolyte layer 107 is set to be between 1-10 μm. In this way, not only the material can be saved, but also a thinner battery can be manufactured to adapt to more use scenarios.

[0080] Optionally, the first solid-state electrolyte layer 104 and the active material coating layer 105 can be subjected to roller pressing after being coated. In this way, the protrusions on the surface of the first solid-state electrolyte layer 104 and the active material coating layer 105 can be flattened to reduce the subsequent infiltration of the second solid-state electrolyte layer 107. In addition, after the roller pressing, the coating thickness of the second solid-state electrolyte layer 107 can be reduced, for example, the coating thickness of the second solid-state electrolyte layer 107 is set to be between 1-10 μm. In this way, not only the material can be saved, but also a thinner battery can be manufactured to adapt to more use scenarios.

[0081] The application provides a preparation method of a pole piece. Considering that there is a thickness difference at the position where the active material and the tab meet, when the solid-state electrolyte paste is coated, the edge close to the tab will have defects such as missing coating and uneven coating. The application provides a preparation method of a pole piece. The first solid-state electrolyte layer is pre-coated on the edges of the active material coating layer, so that the first solid-state electrolyte layer can receive the edges of the active material coating layer. When the second solid-state electrolyte layer is continuously coated on the active material coating layer, since the first solid-state electrolyte has been coated on the edge of the active material, the defects such as missing coating and uneven coating of the edge when the second solid-state electrolyte is coated can be compensated.

[0082] In another embodiment, the application also provides a battery comprising the target pole piece prepared in the above manner. Compared with the scheme of directly introducing a solid-state electrolyte on the pole piece, the qualified rate is increased from 80% to 90% during the manufacture and test of the diaphragm-free battery, an increase of 10%, mainly reflected in the improvement of the short circuit rate index. Experiments have proved that the battery of the application can effectively reduce the occurrence of short circuit rate, and the product yield is high.

[0083] Example 1

[0084] 1. Preparation of negative pole piece

[0085] The negative active material graphite, the binder SBR and the conductive agent SP were mixed in a mass ratio of 8:1:1 to obtain a mixed material, and the mixed material was fully stirred in deionized water to obtain a corresponding negative slurry;

[0086] The first solid-state electrolyte (LLZO) was coated on the first region and the second region of the two side surfaces of the negative current collector copper foil, and dried to obtain a negative first pole piece;

[0087] The negative slurry was uniformly coated on the third region of the negative first pole piece to obtain a negative active material layer with a thickness of 350 μm and a surface density of the negative slurry of 0.023 g / cm 2 , thereby obtaining a negative second pole piece;

[0088] A second solid-state electrolyte (LLZO) with a thickness of 2 μm was coated on the negative second pole piece (first region, second region and third region) by micro-gravure roll coating, and after drying, rolling and slicing, the final negative pole piece was obtained.

[0089] 2. Preparation of positive pole piece

[0090] The positive active material NMC622, the binder PVDF and the conductive agent SP were mixed in a mass ratio of 8:1:1 to obtain a mixed material, and the mixed material was fully stirred in deionized water to obtain a corresponding positive slurry;

[0091] The first solid-state electrolyte (LATP) was coated on the first region and the second region of the two side surfaces of the positive current collector aluminum foil, and dried to obtain a positive first pole piece;

[0092] The positive slurry was uniformly coated on the third region of the positive first pole piece to obtain a positive active material layer with a thickness of 280 μm and a surface density of the positive slurry of 0.041 g / cm 2 , thereby obtaining a positive second pole piece;

[0093] A 2 μm thick second solid electrolyte (LATP) is coated on the second 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.

[0094] 3. Lithium battery assembly

[0095] 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 covered with an aluminum-plastic film, dried, injected with electrolyte, packaged, formed, and capacity divided to obtain a lithium-ion battery.

[0096] Example 2

[0097] 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;

[0098] During the preparation of the positive electrode sheet, the first solid electrolyte is LiP3S4 and the second solid electrolyte is LATP.

[0099] Example 3

[0100] 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 .

[0101] Example 4

[0102] 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;

[0103] During the preparation of the positive electrode sheet, the first solid electrolyte is Li7P3S 11 The second solid electrolyte is Li7P3S 11 .

[0104] Comparative Example 1

[0105] 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;

[0106] The negative electrode slurry was evenly coated on the third area of ​​both sides of the negative electrode current collector copper foil to obtain a thickness of 350 μm and a surface density of 0.023 g / cm 2 a negative electrode active material layer to obtain a negative electrode first electrode sheet;

[0107] A second solid-state electrolyte (LLZO) with a thickness of 2 μm is coated on the negative first electrode sheet (first region, second region, and third region) by microgravure roll coating, and the final negative electrode sheet is obtained after drying, rolling, and slicing.

[0108] 2. Preparation of the positive electrode sheet

[0109] The positive 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 uniformly stirred in NMP to obtain a corresponding positive electrode slurry.

[0110] The positive electrode slurry is uniformly coated on the third region of the two sides of the positive current collector aluminum foil to obtain a positive active material layer with a thickness of 280 μm and a surface density of 0.041 g / cm 2 , and a positive first electrode sheet is obtained.

[0111] A second solid-state electrolyte (LATP) with a thickness of 2 μm is coated on the positive first electrode sheet (first region, second region, and third region) by microgravure roll coating, and the final positive electrode sheet is obtained after drying, rolling, and slicing.

[0112] 3. Assembly of the lithium battery

[0113] The negative electrode sheet prepared above and the positive electrode sheet prepared above are stacked with each other to obtain a battery cell (a battery cell without a separator), the battery cell is packaged in an aluminum plastic film, dried, electrolyte injection, packaged, formed, and tested, and a lithium ion battery is obtained.

[0114] The batteries of Examples 1-4 and Comparative Example 1 are subjected to battery cycle performance testing, and the testing process is as follows: charging and discharging is performed at a current density of 0.1 C, after two cycles of activation, charging and discharging is performed at a current density of 0.2 C, and the cycle is tested for 70 cycles, and the test results are shown in Figure 11 .

[0115] According to the test results shown in Figure 11 , the discharge specific capacity of the batteries of Examples 1-4 after cycle testing is better than that of the battery of Comparative Example 1, which shows that the electrode sheet preparation method of the present application is beneficial to uniform distribution of the electrode sheet coating, and thus the battery has good cycle performance.

[0116] It should be noted that although the operations of the method of the present application are described in a specific order in the accompanying drawings, this does not require or imply that the operations must be performed in this specific order, or that all of the shown operations must be performed to achieve the desired result. On the contrary, the steps depicted in the flowchart can change the order of execution.

[0117] The above description is only the preferred embodiment of the present application and the explanation of the technical principles. It should be understood by those skilled in the art that the scope of the protection of the present application is not limited to the technical solutions formed by the specific combinations of the above technical features. It should also cover other technical solutions formed by the combinations of the above technical features or their equivalent features without departing from the concept of the present application. For example, the technical solutions formed by the mutual replacements of the above features and the technical features disclosed in the present application (but not limited to) with similar functions.

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 to 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, wherein two boundaries of the second solid electrolyte layer in a width direction of the target current collector exceed boundaries 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 meet the following requirements: 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 layer, 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-concave 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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