Electrode piece, electrode assembly, battery and electric device

Abstract

The invention relates to an anode pole piece which comprises an anode current collector and an anode active material layer arranged on the surface of the anode current collector, and the anode active material layer is provided with a first compaction design area; and the compaction density of the anode active material layer in the first compaction design area is gradually reduced and then gradually increased along the extension direction of the pole piece. The invention further relates to a cathode pole piece which comprises a cathode current collector and a cathode active material layer arranged on the surface of the cathode current collector, and the cathode active material layer is provided with a second compaction design area. And the compaction density of the cathode active material layer in the second compaction design area is gradually increased and then gradually reduced along the extension direction of the cathode pole piece. The invention also relates to a corresponding electrode assembly, a battery and an electric device. The active material layer of the pole piece is subjected to specific compaction design, so that the electrolyte infiltration rate of the battery can be improved.

Description

Electrode pieces, electrode assemblies, batteries and electrical devices Technical Field

[0001] The present application relates to the technical field of secondary batteries, and in particular to a pole piece, an electrode assembly, a battery, and an electrical device. Background Art

[0002] In recent years, the application of secondary ion batteries has become increasingly widespread. They are widely used in energy storage power systems such as hydropower, thermal power, wind power, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, and other fields. As secondary batteries have made great progress, higher performance requirements have been placed on them.

[0003] In a cylindrical battery cell, the cathode electrode and the anode electrode need to be stacked and wound to form an electrode assembly with a cylindrical wound structure. The electrode expansion force inside the cylindrical wound structure electrode assembly is relatively large, which leads to the problem of abnormal local electrolyte infiltration in the battery cell during the charging and discharging process, resulting in a low electrolyte infiltration rate of the battery cell.

[0004] Therefore, seeking a pole piece and battery cell structure that can effectively reduce the expansion force of the battery cell pole piece and increase the electrolyte infiltration rate has become one of the research directions that technicians in this field focus on.

[0005] Summary of the Invention

[0006] The present application is made in view of the above-mentioned problems, and one of its purposes is to provide a pole piece, an electrode assembly, a battery and an electrical device, which can enable the battery containing the pole piece and the electrode assembly to have a faster electrolyte infiltration rate.

[0007] To achieve the above objectives, the first aspect of the present application provides an anode electrode plate, comprising an anode current collector and an anode active material layer disposed on the surface of the anode current collector. The anode active material layer has a first compaction design region; within the first compaction design region, the compaction density of the anode active material layer gradually decreases and then gradually increases along the extension direction of the electrode plate. This reduces the expansion force of the anode active material layer on the anode electrode plate during battery charge and discharge, thereby effectively alleviating the problem of local electrolyte infiltration abnormalities and improving the electrolyte infiltration rate of the battery.

[0008] In any embodiment, the first compaction design area covers the entire length of the anode electrode.

[0009] In any embodiment, the first compaction design region is from 6% to 80% of the total length of the anode plate. This arrangement can better reduce the expansion force of the anode active material layer on the anode plate while maintaining the same compaction range (i.e., the difference between the maximum compaction density and the minimum compaction density within the first compaction design region), thereby better increasing the electrolyte infiltration rate.

[0010] In any embodiment, the first compaction design area is from 10% to 70% of the total length of the anode plate. In this way, under the same compaction range, the expansion force of the anode active material layer on the anode plate can be further reduced, and the electrolyte infiltration rate can be further improved.

[0011] In any embodiment, within the first compaction design region, the compaction density of the anode active material layer varies continuously along the extension direction of the anode electrode. This compaction design can effectively reduce the expansion force of the anode active material layer on the anode electrode and improve the electrolyte infiltration rate.

[0012] In any embodiment, within the first compaction design area, the difference between the maximum and minimum compaction density of the anode active material layer along the extension direction of the anode electrode is 0.01 g / cm 3 ~1.00g / cm 3 Setting the difference in compaction density within the first compaction design region within the above range can effectively reduce the expansion force of the anode active material layer on the anode electrode and increase the electrolyte infiltration rate.

[0013] In any embodiment, within the first compaction design area, the difference between the maximum and minimum compaction density of the anode active material layer along the extension direction of the anode electrode is 0.01 g / cm 3 ~0.60g / cm 3 In this way, the expansion force of the anode active material layer can be better reduced, and the electrolyte infiltration rate can be further improved.

[0014] In any embodiment, along the extension direction of the anode electrode sheet, the compaction density of the anode active material layer at both ends of the first compaction design area and the compaction density of the anode active material layer outside the first compaction design area change continuously.

[0015] In any embodiment, within the first compaction design area, the compaction density of the anode active material layer varies gradually along the extension direction of the anode electrode. This compaction design can also reduce the expansion force of the anode active material layer on the anode electrode and increase the electrolyte infiltration rate.

[0016] In any embodiment, within the first compaction design area, the number of gradients of compaction density variation of the anode active material layer is 3 to 15, and the compaction density difference between adjacent gradients is 0.01 g / cm 3 ~0.30g / cm 3 In this way, the effect of the electrolyte infiltration rate can be further improved.

[0017] In any embodiment, within the first compaction design region, the length of the region where the compaction density of the anode active material layer continuously decreases is equal to the length of the region where the compaction density continuously increases, thereby better improving the electrolyte infiltration rate.

[0018] The second aspect of the present application provides a cathode electrode sheet comprising a cathode current collector and a cathode active material layer disposed on the surface of the cathode current collector, wherein the cathode active material layer has a second compaction design region; in the second compaction design region, the compaction density of the cathode active material layer gradually increases and then gradually decreases along the extension direction of the cathode electrode sheet. With this arrangement, when the cathode electrode sheet is combined with an anode electrode sheet to form an electrode assembly, the second compaction design region of the cathode electrode sheet can provide a certain amount of expansion space for the anode active material layer on the anode electrode sheet, thereby effectively alleviating the problem of abnormal local electrolyte infiltration and improving the electrolyte infiltration rate of the battery.

[0019] In any embodiment, the second compaction design area covers the entire length of the cathode electrode.

[0020] In any embodiment, the second compaction design area is from 6% to 80% of the total length of the cathode electrode. This arrangement can better alleviate the problem of abnormal local electrolyte infiltration under the same compaction range and improve the electrolyte infiltration rate of the battery.

[0021] In any embodiment, the second compaction design area is from 10% to 70% of the total length of the cathode electrode, thereby providing better expansion space for the anode active material layer and further improving the electrolyte infiltration rate.

[0022] In any embodiment, within the second compaction design area, the compaction density of the cathode active material layer changes continuously along the extension direction of the cathode electrode sheet.

[0023] In any embodiment, within the second compaction design area, the difference between the maximum and minimum compaction density of the cathode active material layer along the extension direction of the cathode electrode is 0.01 g / cm 3 ~1.50g / cm 3Setting the difference in compaction density within the second compaction design region within the above range can better provide expansion space for the anode active material layer on the anode pole piece used in conjunction with the anode, thereby increasing the electrolyte infiltration rate.

[0024] In any embodiment, within the second compaction design area, the difference between the maximum and minimum compaction density of the cathode active material layer along the extension direction of the cathode electrode is 0.01 g / cm 3 ~0.80g / cm 3 In this way, the anode active material layer can be better provided with expansion space, further improving the electrolyte infiltration rate.

[0025] In any embodiment, along the extension direction of the cathode electrode sheet, the compaction density of the cathode active material layer at both ends of the second compaction design area and the compaction density of the cathode active material layer outside the second compaction design area change continuously.

[0026] In any embodiment, within the second compaction design area, the compaction density of the cathode active material layer changes in a gradient along the extension direction of the cathode electrode sheet.

[0027] In any embodiment, within the second compaction design area, the number of gradients of compaction density change of the cathode active material layer is 3 to 20, and the compaction density difference between adjacent gradients is 0.01 g / cm 3 ~0.50g / cm 3 Such an arrangement can further increase the electrolyte infiltration rate.

[0028] In any embodiment, within the second compaction design region, the length of the region where the compaction density of the cathode active material layer continuously increases is equal to the length of the region where the compaction density continuously decreases, thereby further improving the electrolyte infiltration rate.

[0029] The third aspect of the present application provides an electrode assembly, comprising an anode electrode sheet and a cathode electrode sheet, wherein the anode electrode sheet is the anode electrode sheet of the first aspect of the present application and / or the cathode electrode sheet is the cathode electrode sheet of the second aspect of the present application, which can effectively improve the infiltration rate of the battery electrolyte.

[0030] In any embodiment, the anode electrode piece is the anode electrode piece of the first aspect of the present application, the cathode electrode piece is the cathode electrode piece of the second aspect of the present application, and the first compaction design area on the anode electrode piece corresponds to the second compaction design area on the cathode electrode piece. In this way, the infiltration rate of the battery electrolyte can be further improved.

[0031] In any embodiment, the electrode assembly is a cylindrical electrode assembly formed by stacking and winding the anode electrode sheet and the cathode electrode sheet.

[0032] A fourth aspect of the present application provides a battery comprising a housing, an electrode assembly, and an electrolyte. The electrode assembly comprises the electrode assembly of the third aspect of the present application. The electrode assembly is housed within the inner cavity of the housing. The electrolyte is housed within the inner cavity of the housing and infiltrates the electrode assembly. This battery cell effectively solves the problem of abnormal local electrolyte infiltration during charge and discharge, and has a high electrolyte infiltration rate.

[0033] The fifth aspect of the present application provides an electrical device comprising the battery of the fourth aspect of the present application.

[0034] The anode electrode of the present application designs the compaction density of the first compaction design area of ​​the anode active material layer so that the compaction density of the anode active material layer in the first compaction design area gradually decreases and then gradually increases along the extension direction of the electrode. This can reduce the expansion force of the anode active material layer on the anode electrode during the battery charging and discharging process, thereby alleviating the problem of abnormal local electrolyte infiltration and improving the electrolyte infiltration rate of the battery.

[0035] The cathode electrode of the present application designs the compaction density of the second compaction design area of ​​the cathode active material layer, so that the compaction density of the cathode active material layer in the second compaction design area first gradually increases and then gradually decreases along the extension direction of the electrode; when the cathode electrode is combined with the anode electrode (especially the second compaction design area is combined with the first compaction design area of ​​the cathode electrode of the present application) to form an electrode assembly, the second compaction design area of ​​the cathode electrode can provide a certain expansion space for the anode active material layer on the anode electrode, thereby effectively alleviating the problem of abnormal local electrolyte infiltration and improving the electrolyte infiltration rate of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] FIG1 is a partial schematic diagram of the pairing of the anode electrode piece and the cathode electrode piece in Example 1 of the present application.

[0037] FIG2 is a partial schematic diagram of the pairing of the anode electrode and the cathode electrode in Example 2 of the present application.

[0038] FIG3 is a partial schematic diagram of the pairing of the anode electrode and the cathode electrode in Example 13 of the present application.

[0039] FIG4 is a partial schematic diagram of the pairing of the anode electrode and the cathode electrode in Example 14 of the present application.

[0040] FIG5 is a schematic diagram of an electrical device using a battery as a power source according to an embodiment of the present application.

[0041] Description of reference numerals:

[0042] 1. Anode electrode; 2. Cathode electrode; 3. Electrical device; 11. Anode current collector; 12. Anode active material layer; 13. First compaction design area; 21. Cathode current collector; 22. Cathode active material layer; 23. Second compaction design area. DETAILED DESCRIPTION

[0043] Below, the embodiments of the electrode sheet, electrode assembly, battery cell, secondary battery and electrical device of the present application are described in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there may be cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structure are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0044] The "ranges" disclosed herein are defined in terms of lower and upper limits, where a given range is defined by selecting a lower limit and an upper limit, and the selected lower and upper limits define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive of the end values ​​and may be combined arbitrarily, i.e., any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also contemplated. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, the following ranges are all contemplated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In this application, unless otherwise indicated, the numerical range "ab" is a shorthand representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0045] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0046] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0047] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0048] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0049] Unless otherwise specified, the term "or" is used in this application to be inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied if any of the following conditions are met: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0050] Cylindrical battery cells require stacking and winding cathode and anode electrodes to form a cylindrically wound electrode assembly. This electrode assembly exhibits significant expansion forces, which can lead to localized electrolyte wetting during charge and discharge, resulting in a low electrolyte wetting rate. Therefore, finding electrode and battery structures that can effectively reduce the expansion forces of battery cell electrodes and increase the electrolyte wetting rate has become a key research focus for those skilled in the art.

[0051] The inventors have discovered a pole piece that can effectively reduce the pole piece expansion force by compacting the active material layer on the current collector in a specific manner, solving the problem of abnormal local electrolyte infiltration during charging and discharging, thereby increasing the electrolyte infiltration rate of the battery.

[0052] In some embodiments, the first aspect of the present application provides an anode electrode sheet, comprising an anode current collector and an anode active material layer disposed on the surface of the anode current collector, the anode active material layer having a first compaction design area; within the first compaction design area, the compaction density of the anode active material layer first gradually decreases and then gradually increases along the extension direction of the electrode sheet.

[0053] The anode pole piece of the present application sets a first compaction design area on the anode active material layer, so that the compaction density of the anode active material layer in the first compaction design area first gradually decreases and then gradually increases along the extension direction of the pole piece. That is, within the first compaction design area, the compaction density of the anode active material layer at both ends in the extension direction of the pole piece is greater than the compaction density in the middle. Since at the same coating surface density, the compaction density is inversely proportional to the thickness of the anode active material layer (h = CW / PD, where h is the thickness of the material layer, CW is the coating surface density, and PD is the compaction density); correspondingly, the thickness of the anode active material layer at both ends of the first compaction design area is less than the thickness in the middle. Such a setting can reduce the expansion force of the anode active material layer on the anode pole piece during the charge and discharge process of the battery, thereby effectively alleviating the problem of abnormal local electrolyte infiltration and improving the electrolyte infiltration rate of the battery.

[0054] Research has found that during charge and discharge, the anode active material layer on the anode plate experiences greater expansion force near the middle of the plate's length, while the expansion force at the ends is relatively smaller. Accordingly, the anode active material layer near the middle also experiences a greater expansion rate. By gradually decreasing and then increasing the compaction density of the anode active material layer within the first compaction design area along the plate's extension, this better aligns with the changing expansion force of the active material and improves the electrolyte infiltration rate.

[0055] It should be noted that “the compaction density first gradually decreases and then gradually increases along the extension direction of the pole piece” can mean first continuously decreasing and then continuously increasing, or first decreasing according to a certain gradient and then increasing according to a certain gradient.

[0056] In any embodiment, the compaction design can be formed by uniformly coating the anode active material on the upper and lower surfaces of the anode current collector, drying the anode active material, and then rolling the anode active material on the upper and lower surfaces using a roller press. By adjusting the gap between the upper and lower rollers of the roller press, the compaction density of each part can be adjusted.

[0057] In some embodiments, the first compaction design region covers the entire length of the anode plate. That is, the first compaction design region extends from the start point to the end point of the entire anode plate in the direction of extension. In other words, the compaction density of the anode active material layer on the anode plate is designed according to the above-mentioned rules.

[0058] In some embodiments, the first compaction design region is from 6% to 80% of the total length of the anode plate. In other words, the first compaction design region only includes a portion of the total length of the anode plate; that is, compaction density design is performed only on the region from 6% to 80% of the length of the starting point of the anode plate.

[0059] It should be noted that the starting position of the anode electrode in the extending direction is defined as the 0% length position, and the ending position is defined as the 100% length position.

[0060] Research has found that the expansion force of the anode active material layer on the anode plate during charge and discharge is not uniform across all parts of the anode plate. Instead, the expansion of the anode active material layer is relatively large in the region between 6% and 80% of the total length of the anode plate. By setting the first compaction design region to the region between 6% and 80% of the total length of the anode plate, the expansion force of the anode active material layer on the anode plate can be further reduced, while maintaining the same compaction range (i.e., the difference between the maximum and minimum compaction densities within the first compaction design region), thereby improving the electrolyte infiltration rate.

[0061] In some embodiments, the first compaction design area is from 10% to 70% of the total length of the anode electrode. Further research has found that setting the first compaction design area from 10% to 70% of the total length of the anode electrode can further reduce the expansion force of the anode active material layer and further increase the electrolyte infiltration rate.

[0062] In any embodiment, the first compaction design area occupies the entire width of the anode plate, that is, the first compaction design area covers the entire width of the anode plate.

[0063] In any embodiment, within the first compaction design region, the compaction density of the anode active material layer varies continuously along the extension direction of the anode electrode sheet. That is, within the first compaction design region, the compaction density of the anode active material layer varies continuously along the extension direction of the anode electrode sheet, without any sudden changes in compaction density. Specifically, the compaction density within the first compaction design region may vary according to a mathematical function, such as a linear function, a quadratic function, or the like.

[0064] In any embodiment, within the first compaction design area, the difference in compaction density of the anode active material layer along the extension direction of the anode electrode sheet (the difference between the maximum and minimum values, i.e., the compaction range) is 0.01 g / cm 3 ~1.00g / cm 3 In other words, within the first compaction design region, the difference between the maximum and minimum compaction densities of the anode active material layer is 0.01 g / cm 3 ~1.00g / cm 3 Setting the difference in compaction density within the first compaction design region within the above range can effectively reduce the expansion force of the anode active material layer on the anode electrode and increase the electrolyte infiltration rate.

[0065] It is understood that within the first compaction design area, the difference between the maximum and minimum compaction density of the anode active material layer along the extension direction of the anode electrode sheet may be, but is not limited to, 0.01 g / cm 3 , 0.05g / cm 3 , 0.10g / cm 3 , 0.20g / cm 3 , 0.30g / cm 3 , 0.40g / cm 3 , 0.50g / cm 3 、0.60g / cm 3 , 0.70g / cm 3 、0.80g / cm 3 , 0.90g / cm 3 , 1.00g / cm 3 .

[0066] In some embodiments, within the first compaction design area, the difference between the maximum and minimum compaction density of the anode active material layer along the extension direction of the anode electrode is 0.01 g / cm 3 ~0.60g / cm 3 Further research has found that setting the difference in compaction density within the first compaction design area within the above range can better reduce the expansion force of the anode active material layer and further increase the electrolyte infiltration rate.

[0067] In any embodiment, along the extension direction of the anode electrode sheet, the compaction density of the anode active material layer at both ends of the first compaction design region changes continuously with the compaction density of the anode active material layer outside the first compaction design region. In other words, the compaction density of the anode active material layer at both ends of the first compaction design region and the compaction density of the anode active material layer outside the first compaction design region transition continuously, without any sudden change in compaction density.

[0068] In any embodiment, within the first compaction design region, the compaction density of the anode active material layer varies in a gradient along the extension direction of the anode electrode sheet. That is, within the first compaction design region, the compaction density of the anode active material layer along the extension direction of the anode electrode sheet is discontinuous, but rather varies according to multiple gradients, each of which may have a different compaction density. This compaction design can also reduce the expansion force of the anode active material layer on the anode electrode sheet and increase the electrolyte infiltration rate.

[0069] In any embodiment, within the first compaction design area, the number of gradients of compaction density variation of the anode active material layer is 3 to 15, and the compaction density difference between adjacent gradients is 0.01 g / cm 3 ~0.30g / cm 3 .

[0070] It is understood that the number of gradients of compaction density variation of the anode active material layer within the first compaction design area may be, but is not limited to, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15. The compaction density difference between adjacent gradients may be, but is not limited to, 0.01 g / cm 3 , 0.02g / cm 3 , 0.05g / cm 3 , 0.08g / cm 3 , 0.10g / cm 3 , 0.12 g / cm 3 , 0.15g / cm 3 , 0.18g / cm 3 , 0.20g / cm 3 , 0.22g / cm 3 , 0.25g / cm 3 , 0.28g / cm 3 , 0.30g / cm 3 .

[0071] In any embodiment, within the first compaction design region, the length of the region where the compaction density of the anode active material layer continuously decreases is equal to the length of the region where the compaction density continuously increases. Furthermore, the compaction density of the anode active material layer is symmetrically distributed along a cross section in the first compaction design region perpendicular to the extension direction of the anode electrode sheet. That is, the compaction density of the anode active material layer on either side of the cross section in the first compaction design region corresponds to each other, and the compaction density at the same distance on either side of the cross section is equal.

[0072] In some embodiments, the second aspect of the present application provides a cathode electrode, comprising a cathode current collector and a cathode active material layer disposed on the surface of the cathode current collector, the cathode active material layer having a second compaction design area; within the second compaction design area, the compaction density of the cathode active material layer first gradually increases and then gradually decreases along the extension direction of the cathode electrode.

[0073] The cathode electrode of the present application sets a second compaction design area on the cathode active material layer, so that the compaction density of the cathode active material layer in the second compaction design area first gradually increases and then gradually decreases along the extension direction of the electrode. That is, within the second compaction design area, the compaction density of the cathode active material layer at both ends in the extension direction of the electrode is less than the compaction density in the middle. Correspondingly, the thickness of the cathode active material layer at both ends of the second compaction design area is greater than the thickness in the middle. With such a setting, when the cathode electrode is combined with the anode electrode to form an electrode assembly, the second compaction design area of ​​the cathode electrode can provide a certain expansion space for the anode active material layer on the anode electrode, thereby effectively alleviating the problem of abnormal local electrolyte infiltration and improving the electrolyte infiltration rate of the battery.

[0074] It should be noted that the cathode electrode piece can be used in conjunction with the anode electrode piece of the first aspect of the present application to form an electrode assembly, or it can be used in conjunction with an ordinary anode electrode piece to form an electrode assembly. Preferably, the cathode electrode piece is used in conjunction with the anode electrode piece of the first aspect of the present application. In this way, on the one hand, the compaction design within the first compaction design area can reduce the expansion of the anode active material layer, and at the same time, the compaction design within the second compaction design area can provide a certain expansion space for the anode active material layer. The combined effect of these two aspects can more effectively improve the infiltration rate of the battery electrolyte. When the cathode electrode piece is used in conjunction with the anode electrode piece of the first aspect of the present application, it is preferred that the positions of the first compaction design area and the second compaction design area correspond to each other.

[0075] In any embodiment, the compaction design can be formed by evenly coating the cathode active material on the upper and lower surfaces of the cathode current collector, drying the cathode active material, and then rolling the cathode active material on the upper and lower surfaces using a roller press. By adjusting the gap between the upper and lower rollers of the roller press, the compaction density of each part can be adjusted.

[0076] In some embodiments, the second compaction design region extends over the entire length of the cathode plate. That is, the second compaction design region extends from the start point to the end point of the entire length of the cathode plate. In other words, the compaction density of the cathode active material layer on the cathode plate is designed according to the above-described principles.

[0077] In some embodiments, the second compaction design area is from 6% to 80% of the total length of the cathode electrode. In other words, the second compaction design area only includes a portion of the total length of the cathode electrode; that is, the compaction density design is only performed on the area from 6% to 80% of the length of the cathode electrode.

[0078] It should be noted that the starting position of the cathode electrode in the length direction is defined as the 0% length position, and the end position is defined as the 100% length position.

[0079] During the charge and discharge process, the expansion force of the anode active material layer on the anode plate is not uniform across the board. Instead, the anode active material layer expands more significantly in the region between 6% and 80% of the total length of the anode plate. By correspondingly positioning the second compaction design region between 6% and 80% of the total length of the cathode plate, greater expansion space can be provided for the anode plate that matches the cathode plate, while maintaining the same compaction range (i.e., the difference between the maximum and minimum compaction densities within the second compaction design region), thereby improving the electrolyte infiltration rate.

[0080] In some embodiments, the second compaction design region is from 10% to 70% of the total length of the cathode electrode. Setting the second compaction design region from 10% to 70% of the total length of the cathode electrode can better provide expansion space for the anode active material layer, further improving the electrolyte infiltration rate.

[0081] In any embodiment, the second compaction design area occupies the entire width of the cathode electrode piece, that is, the second compaction design area covers the entire width of the cathode electrode piece.

[0082] In any embodiment, within the second compaction design region, the compaction density of the cathode active material layer varies continuously along the extension direction of the cathode electrode sheet. That is, within the second compaction design region, the compaction density of the cathode active material layer varies continuously along the extension direction of the cathode electrode sheet, without any sudden changes in compaction density. Specifically, the compaction density within the second compaction design region can vary according to a mathematical function, such as a linear function, a quadratic function, or the like.

[0083] In any embodiment, within the second compaction design area, the difference between the maximum and minimum compaction density of the cathode active material layer along the extension direction of the cathode electrode (i.e., the compaction range) is 0.01 g / cm 3 ~1.50g / cm 3 In other words, within the second compaction design region, the difference between the maximum and minimum compaction densities of the cathode active material layer is 0.01 g / cm 3 ~1.50g / cm 3 Setting the difference in compaction density within the second compaction design region within the above range can better provide expansion space for the anode active material layer on the anode pole piece used in conjunction with the anode, thereby increasing the electrolyte infiltration rate.

[0084] It can be understood that within the second compaction design area, the difference between the maximum and minimum compaction density of the cathode active material layer along the extension direction of the cathode electrode sheet can be, but is not limited to, 0.01 g / cm3 , 0.05g / cm 3 , 0.10g / cm 3 , 0.20g / cm 3 , 0.30g / cm 3 , 0.40g / cm 3 , 0.50g / cm 3 、0.60g / cm 3 , 0.70g / cm 3 、0.80g / cm 3 , 0.90g / cm 3 , 1.00g / cm 3 , 1.10g / cm 3 , 1.20g / cm 3 , 1.30g / cm 3 , 1.40g / cm 3 , 1.50g / cm 3 .

[0085] In some embodiments, within the second compaction design area, the difference between the maximum and minimum compaction density of the cathode active material layer along the extension direction of the cathode electrode is 0.01 g / cm 3 ~0.80g / cm 3 Further research has found that setting the difference in compaction density within the second compaction design area within the above range can better provide expansion space for the anode active material layer and further improve the electrolyte infiltration rate.

[0086] In any embodiment, along the extension direction of the cathode electrode sheet, the compaction density of the cathode active material layer at both ends of the second compaction design region changes continuously with the compaction density of the cathode active material layer outside the second compaction design region. In other words, the compaction density of the cathode active material layer at both ends of the second compaction design region and the compaction density of the cathode active material layer outside the second compaction design region transition continuously, without any sudden change in compaction density.

[0087] In any embodiment, within the second compaction design region, the compaction density of the cathode active material layer varies in a gradient along the extension direction of the cathode electrode sheet. That is, within the second compaction design region, the compaction density of the cathode active material layer along the extension direction of the cathode electrode sheet is discontinuous, but rather varies according to multiple gradients, each of which may have a different compaction density. This compaction design also provides expansion space for the anode active material layer on the anode electrode sheet, thereby increasing the electrolyte infiltration rate.

[0088] In any embodiment, within the second compaction design area, the number of gradients of compaction density change of the cathode active material layer is 3 to 20, and the compaction density difference between adjacent gradients is 0.01 g / cm 3 ~0.50g / cm 3 .

[0089] It is understood that the number of gradients of compaction density variation of the cathode active material layer in the second compaction design area may be, but is not limited to, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20. The compaction density difference between adjacent gradients may be, but is not limited to, 0.01 g / cm 3 , 0.02g / cm 3 , 0.05g / cm 3 , 0.08g / cm 3 , 0.10g / cm 3 , 0.12g / cm 3 , 0.15g / cm 3 , 0.18g / cm 3 , 0.20g / cm 3 , 0.22g / cm 3 , 0.25g / cm 3 , 0.28g / cm 3 , 0.30g / cm 3 , 0.32g / cm 3 , 0.34g / cm 3 , 0.36g / cm 3 , 0.38g / cm 3 , 0.40g / cm 3 , 0.42g / cm 3 , 0.45g / cm 3 , 0.48g / cm 3 , 0.50g / cm 3 .

[0090] In any embodiment, within the second compaction design region, the length of the region where the compaction density of the cathode active material layer continuously increases is equal to the length of the region where the compaction density continuously decreases. Furthermore, the compaction density of the cathode active material layer is symmetrically distributed along a cross section in the second compaction design region perpendicular to the extension direction of the cathode electrode sheet. That is, the compaction density of the cathode active material layer on either side of the cross section in the second compaction design region corresponds to each other, and the compaction density at the same distance on either side of the cross section is equal.

[0091] In some embodiments, the third aspect of the present application provides an electrode assembly comprising an anode plate and a cathode plate, wherein the anode plate is the anode plate of the first aspect of the present application and / or the cathode plate is the cathode plate of the second aspect of the present application.

[0092] In some embodiments, the anode electrode of the electrode assembly is the anode electrode of the first aspect of the present application, and the cathode electrode is a common cathode electrode, that is, the compaction density of the cathode active material layer on the cathode electrode is consistent everywhere.

[0093] In some embodiments, the anode electrode of the electrode assembly is a common anode electrode, that is, the anode active material layer on the anode electrode has a uniform compaction density, and the cathode electrode is the cathode electrode of the second aspect of the present application.

[0094] In some embodiments, the anode electrode of the electrode assembly adopts the anode electrode of the first aspect of the present application, and the cathode electrode adopts the cathode electrode of the second aspect of the present application.

[0095] By matching and combining the anode pole piece of the first aspect of the present application and / or the cathode pole piece of the second aspect of the present application to form an electrode assembly, the infiltration rate of the battery electrolyte can be effectively improved by designing the compaction density in the first compaction design area and the second compaction design area. Preferably, the anode pole piece of the first aspect of the present application and the cathode pole piece of the second aspect of the present application are matched and combined to form an electrode assembly, and the infiltration rate of the electrolyte can be further improved by matching the compaction density design in the first compaction design area and the second compaction design area.

[0096] In any embodiment, the electrode assembly is a cylindrical electrode assembly formed by stacking and winding the anode and cathode electrodes. In cylindrical battery cells, the expansion of the electrode active material during charge and discharge is more likely to cause local electrolyte infiltration anomalies. The structural design of the present application in cylindrical electrode assemblies can effectively alleviate local electrolyte infiltration anomalies.

[0097] In some embodiments, a fourth aspect of the present application provides a battery comprising a housing, an electrode assembly, and an electrolyte, wherein the housing has an inner cavity, the electrode assembly comprises the electrode assembly of the third aspect of the present application, the electrode assembly is housed in the inner cavity of the housing, and the electrolyte is housed in the inner cavity of the housing and infiltrates the electrode assembly. The battery cell of the present application effectively solves the problem of abnormal local electrolyte infiltration during charge and discharge, and has a high electrolyte infiltration rate.

[0098] In some embodiments, the fifth aspect of the present application provides an electrical device, comprising the battery of the fourth aspect of the present application, wherein the battery serves as a power source for the electrical device to provide electrical energy for the electrical device.

[0099] The battery and the electrical device of the present application will be described below with reference to the accompanying drawings as appropriate.

[0100] Typically, a battery consists of a cathode plate 2, an anode plate 1, an electrolyte, and a separator. During the battery's charge and discharge processes, active ions are inserted and removed between the cathode plate 2 and the anode plate 1. The electrolyte conducts ions between the cathode plate 2 and the anode plate 1. The separator, located between the cathode plate 2 and the anode plate 1, primarily prevents short circuits between the cathode and anode electrodes while allowing ions to pass through.

[0101] [Cathode plate]

[0102] The cathode electrode 2 includes a cathode current collector 21 and a cathode film layer (ie, a cathode active material layer 22 ) disposed on at least one surface of the cathode current collector 21 , wherein the cathode film layer includes a cathode active material.

[0103] As an example, the cathode current collector 21 has two opposite surfaces in its thickness direction, and the cathode film layer is disposed on either or both of the two opposite surfaces of the cathode current collector 21 .

[0104] In some embodiments, the cathode current collector 21 may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector may be formed by forming a metal material on a polymer material substrate. Among them, the metal material includes but is not limited to aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc. Polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0105] In some embodiments, the cathode active material may include cathode active materials for batteries that are well known in the art. As an example, the cathode active material may include at least one of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as battery cathode active materials may also be used. These cathode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3O2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2) and its modified compounds. Examples of olivine-structured lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

[0106] The weight ratio of the cathode active material in the cathode film layer is 80 wt % to 100 wt %, based on the total weight of the cathode film layer.

[0107] In some embodiments, the cathode film layer may further optionally include a binder. For example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorinated acrylate resin. The binder may be present in the cathode film layer in an amount ranging from 0% to 20% by weight, based on the total weight of the cathode film layer.

[0108] In some embodiments, the cathode film layer may further include a conductive agent. For example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. The weight ratio of the conductive agent in the cathode film layer is 0% to 20% by weight, based on the total weight of the cathode film layer.

[0109] In some embodiments, the cathode electrode sheet 2 can be prepared by the following method: the components for preparing the cathode electrode sheet 2, such as the cathode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as N-methylpyrrolidone) to form a cathode slurry, wherein the solid content of the cathode slurry is 40wt% to 80wt%, and the viscosity at room temperature is adjusted to 5000mPa·s to 25000mPa·s, the cathode slurry is coated on the surface of the cathode current collector 21, and after drying, it is cold-pressed by a cold rolling mill to form the cathode electrode sheet 2.

[0110] In some embodiments, a second compaction design region 23 is further provided on the cathode active material layer 22 of the cathode plate 2. The compaction density is designed in accordance with the specific method of the present application within the second compaction design region 23. Some examples of the cathode plate 2 are shown in Figures 1 to 4.

[0111] [Anode plate]

[0112] The anode electrode 1 includes an anode current collector 11 and an anode film layer (ie, an anode active material layer 12 ) disposed on at least one surface of the anode current collector 11 , wherein the anode film layer includes an anode active material.

[0113] As an example, the anode current collector 11 has two surfaces opposite to each other in its thickness direction, and the anode film layer is provided on either one or both of the two opposite surfaces of the anode current collector 11 .

[0114] In some embodiments, the anode current collector 11 may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material on a polymer material substrate. Among them, the metal material includes but is not limited to copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc., and the polymer material substrate includes but is not limited to polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE) and other substrates.

[0115] In some embodiments, the anode active material may be an anode active material for a battery that is well known in the art. As an example, the anode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material may be selected from at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxides, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as battery anode active materials may also be used. These anode active materials may be used alone or in combination of two or more.

[0116] In some embodiments, the anode film layer may further include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS). The weight ratio of the binder in the anode film layer is 0% to 30% by weight, based on the total weight of the anode film layer.

[0117] In some embodiments, the anode film layer may further include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. The weight ratio of the conductive agent in the anode film layer is 0% to 20% by weight, based on the total weight of the anode film layer.

[0118] In some embodiments, the anode film layer may further include other additives, such as a thickener (e.g., sodium carboxymethyl cellulose (CMC-Na)), etc. The weight ratio of the other additives in the anode film layer is 0 wt % to 15 wt %, based on the total weight of the anode film layer.

[0119] In some embodiments, the anode electrode sheet can be prepared by the following method: the above-mentioned components for preparing the anode electrode sheet, such as the anode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as deionized water) to form an anode slurry, wherein the solid content of the anode slurry is 30wt% to 70wt%, and the viscosity at room temperature is adjusted to 2000mPa·s to 10000mPa·s; the obtained anode slurry is coated on the anode current collector 11, and after a drying process, cold pressing, such as rolling, is performed to obtain the anode electrode sheet 1.

[0120] In some embodiments, a first compaction design region 13 is further provided on the anode active material layer 12 of the anode plate 1. The compaction density is designed in accordance with the specific method of the present application within the first compaction design region 13. Some examples of the anode plate 1 are shown in Figures 1 to 4.

[0121] [Electrolyte]

[0122] The electrolyte acts as a conductor of ions between the cathode electrode 2 and the anode electrode 1. The present application does not specifically limit the type of electrolyte, and the electrolyte can be selected based on the needs. For example, the electrolyte can be liquid, gel, or solid.

[0123] In some embodiments, the electrolyte is an electrolyte comprising an electrolyte salt and a solvent.

[0124] In some embodiments, the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0125] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0126] In some embodiments, the electrolyte may further include additives. For example, the additives may include anode film-forming additives, cathode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, and additives that improve battery high or low temperature performance.

[0127] [Isolation film]

[0128] In some embodiments, the battery further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical and mechanical stability can be selected.

[0129] In some embodiments, the material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0130] In some embodiments, the isolation film has a thickness of 6 μm to 40 μm, and may optionally be 12 μm to 20 μm.

[0131] In some embodiments, the cathode electrode sheet 2 , the anode electrode sheet 1 , and the separator can be formed into an electrode assembly through a winding process or a lamination process.

[0132] In some embodiments, the battery may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte.

[0133] In some embodiments, the battery outer packaging may be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. Alternatively, the battery outer packaging may be a soft shell, such as a pouch-type soft shell. The soft shell may be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0134] The present application has no particular limitation on the shape of the secondary battery, which may be cylindrical, square, or any other shape.

[0135] In some embodiments, the outer packaging may include a shell and a cover plate. The shell may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose a receiving cavity. The shell has an opening connected to the receiving cavity, and the cover plate can be covered on the opening to close the receiving cavity. The cathode electrode sheet 2, the anode electrode sheet 1 and the separator can be formed into an electrode assembly through a winding process or a lamination process. The electrode assembly is encapsulated in the receiving cavity. The electrolyte is impregnated in the electrode assembly. The number of electrode assemblies contained in the battery can be one or more, and those skilled in the art can select according to specific actual needs.

[0136] In some embodiments, batteries may be assembled into a battery module. The number of batteries contained in the battery module may be one or more. The specific number may be selected by those skilled in the art based on the application and capacity of the battery module.

[0137] In a battery module, multiple batteries can be arranged in sequence along the length of the battery module. Of course, they can also be arranged in any other manner. Furthermore, the multiple batteries can be fixed using fasteners.

[0138] Optionally, the battery module may further include a housing having a receiving space, wherein the plurality of batteries are received in the receiving space.

[0139] In some embodiments, the battery modules described above may also be assembled into a battery pack. The battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art based on the application and capacity of the battery pack.

[0140] A battery pack may include a battery box and multiple battery modules disposed within the box. The battery box comprises an upper case and a lower case. The upper case can be placed over the lower case to form an enclosed space for accommodating the battery modules. The multiple battery modules can be arranged in any manner within the battery box.

[0141] In addition, the present application also provides an electric device 3, which includes at least one of the batteries, battery modules, or battery packs provided in the present application. The battery, battery module, or battery pack can be used as a power source for the electric device 3, or as an energy storage unit for the electric device 3. The electric device 3 may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but is not limited thereto.

[0142] As the electrical device 3 , a battery, a battery module or a battery pack can be selected according to its usage requirements.

[0143] Figure 5 shows an example of an electric device 3. The electric device 3 is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the electric device 3, a battery pack or battery module can be used.

[0144] Another example device may be a mobile phone, a tablet computer, a laptop computer, etc. Such a device is usually required to be light and thin, and may use a battery as a power source.

[0145] Example

[0146] In order to make the technical problems, technical solutions and beneficial effects solved by this application clearer, the application will be further described in detail below with reference to the embodiments and drawings. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present application and its applications. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0147] If no specific techniques or conditions are specified in the examples, the experiments were carried out according to the techniques or conditions described in the literature in the field or according to the product instructions. All reagents or instruments used without specifying the manufacturer are commercially available conventional products.

[0148] Example 1:

[0149] (1) Anode electrode preparation

[0150] a. Graphite, conductive agent, binder, and dispersant were added to a stirring tank in a weight ratio of 97:0.5:1.5:1, and deionized water was added to obtain a mixed solution. The amount of deionized water added was 1 times the total mass of graphite, conductive agent, binder, and dispersant; the stirring tank was rotated at a high speed of 1200 r / min for 4 h; the mixed solution was evenly coated on the copper foil using an automatic coating machine (coating CW = 156 mg / 1540 mm 2 ) Place the coated copper foil in an oven and bake it at 120°C for 20 minutes. The electrode is reserved for subsequent compaction design.

[0151] b. The density gradient (PD) design can be confirmed by the change of the electrode thickness (h), and the calculation formula is: h = CW / PD. The density range design is achieved by periodically changing the gap between the upper and lower rollers. The dried electrode is rolled with a roller press, and the length of a single battery electrode is used as a rolling cycle. The density setting length range is 0% to 100% of the full length of the electrode, and the density range is 0.3g / cm 3 The thickness of the pole piece in the compaction design area changes continuously from 0.134mm to 0.161mm and then to 0.134mm.

[0152] (2) Cathode electrode preparation

[0153] Lithium iron phosphate, conductive agent, binder, and dispersant were added to a stirring tank in a weight ratio of 97:1:1.5:0.5, and deionized water was added to obtain a mixed solution. The amount of deionized water added was 0.6 times the total mass of graphite, conductive agent, binder, and dispersant. The stirring tank was rotated at a high speed of 1200 r / min for 4 hours. The mixed solution was evenly coated on aluminum foil using an automatic coating machine (coating CW = 340 mg / 1540 mm 2 ); Place the coated copper foil in an oven and bake at 120°C for 30 minutes. Use a roller press to roll the dried electrode to a constant thickness of 0.191mm.

[0154] (3) Battery cell assembly

[0155] The cathode and anode electrodes are paired and wound with the separator. The tabs are then shaped, the adapters are laser welded, the top cover is welded, the liquid is injected, and the sealing pins are welded to complete the battery cell assembly. A partial schematic diagram of the cathode and anode electrodes of this embodiment forming an electrode assembly is shown in Figure 1.

[0156] Battery cell testing

[0157] Soaking Time Test Method: The test current and cutoff voltage can be modified based on actual measurements, application requirements, and the actual battery cell chemistry and health status. In this experiment, the LFP battery cells were discharged to 2.5V at a 1C rate. The time from discharge cutoff (i.e., discharge to 2.5V) to electrolyte equilibrium (electrolyte level equilibrium is indicated by a constant electrolyte level within 2 hours). The test results are shown in Table 1.

[0158] Example 2:

[0159] The same electrode formula, coating process and battery cell assembly method as in Example 1 were used. The anode electrode compaction setting length range was 6% to 80% of the full length of the electrode, and the compaction range was 0.3g / cm 3 The thickness of the electrode sheet in the compaction design area continuously changes from 0.134mm to 0.161mm and then to 0.134mm. The cathode electrode sheet is rolled using a roller press to a uniform thickness of 0.191mm. A partial schematic diagram of the cathode and anode electrode sheets of this embodiment paired to form an electrode assembly is shown in Figure 2.

[0160] The soaking time of the assembled battery cells was tested using the same testing method as in Example 1. The test results are shown in Table 1.

[0161] Example 3:

[0162] The same electrode formula, coating process and battery cell assembly method as in Example 1 were used. The anode electrode compaction setting length range was 10% to 70% of the full length of the electrode, and the compaction range was 0.3g / cm 3 The thickness of the electrode in the compaction design area changes continuously from 0.134mm to 0.161mm and then to 0.134mm; the cathode electrode is rolled to a constant thickness of 0.191mm using a roller press.

[0163] The soaking time of the assembled battery cells was tested using the same testing method as in Example 1. The test results are shown in Table 1.

[0164] Example 4:

[0165] The same electrode formula, coating process and battery cell assembly method as in Example 1 were used. The anode electrode compaction setting length range was 20% to 50% of the full length of the electrode, and the compaction range was 0.3g / cm 3 The thickness of the electrode in the compaction design area changes continuously from 0.134mm to 0.161mm and then to 0.134mm; the cathode electrode is rolled to a constant thickness of 0.191mm using a roller press.

[0166] The soaking time of the assembled battery cells was tested using the same testing method as in Example 1. The test results are shown in Table 1.

[0167] Example 5:

[0168] The same electrode formula, coating process and battery cell assembly method as in Example 1 were used. The anode electrode compaction setting length range was 30% to 40% of the full length of the electrode, and the compaction range was 0.3g / cm 3 The thickness of the electrode in the compaction design area changes continuously from 0.134mm to 0.161mm and then to 0.134mm; the cathode electrode is rolled to a constant thickness of 0.191mm using a roller press.

[0169] The soaking time of the assembled battery cells was tested using the same testing method as in Example 1. The test results are shown in Table 1.

[0170] Example 6:

[0171] The same electrode formula, coating process and battery cell assembly method as in Example 1 were used. The anode electrode compaction setting length range was 6% to 80% of the full length of the electrode, and the compaction range was 0.1g / cm 3 The thickness of the electrode in the compaction design area changes continuously from 0.134mm to 0.161mm and then to 0.134mm; the cathode electrode is rolled to a constant thickness of 0.191mm using a roller press.

[0172] The soaking time of the assembled battery cells was tested using the same testing method as in Example 1. The test results are shown in Table 1.

[0173] Example 7:

[0174] The same electrode formulation, coating process and battery cell assembly method as in Example 1 were used. The anode electrode compaction length range was 6% to 80%, and the compaction range was 0.2 g / cm 3 The thickness of the electrode in the compaction design area changes continuously from 0.134mm to 0.161mm and then to 0.134mm; the cathode electrode is rolled to a constant thickness of 0.191mm using a roller press.

[0175] The soaking time of the assembled battery cells was tested using the same testing method as in Example 1. The test results are shown in Table 1.

[0176] Example 8:

[0177] The same electrode formula, coating process and battery cell assembly method as in Example 1 were used. The cathode electrode compaction setting length range was 0% to 100%, and the compaction range was 0.3 g / cm 3 The thickness of the electrode in the compaction design area changes continuously from 0.213mm to 0.191mm and then to 0.213mm; the anode electrode is rolled to a constant thickness of 0.134mm using a roller press.

[0178] The soaking time of the assembled battery cells was tested using the same testing method as in Example 1. The test results are shown in Table 1.

[0179] Example 9:

[0180] The same electrode formula, coating process and battery cell assembly method as in Example 1 were used. The cathode electrode compaction setting length range was 6% to 80%, and the compaction range was 0.3 g / cm 3 The thickness of the electrode in the compaction design area changes continuously from 0.213mm to 0.191mm and then to 0.213mm; the anode electrode is rolled to a constant thickness of 0.134mm using a roller press.

[0181] The soaking time of the assembled battery cells was tested using the same testing method as in Example 1. The test results are shown in Table 1.

[0182] Example 10:

[0183] The same electrode formula, coating process and battery cell assembly method as in Example 1 were used. The cathode electrode compaction setting length range was 6% to 80%, and the compaction range was 0.1 g / cm 3 The thickness of the electrode in the compaction design area changes continuously from 0.198mm to 0.191mm and then to 0.198mm; the anode electrode is rolled to a constant thickness of 0.134mm using a roller press.

[0184] The soaking time of the assembled battery cells was tested using the same testing method as in Example 1. The test results are shown in Table 1.

[0185] Example 11:

[0186] The same electrode formulation, coating process and battery cell assembly method as in Example 1 were used. The compression setting length intervals of the anode and cathode electrodes were both 0% to 100%, and the anode electrode compression range was 0.3 g / cm 3 The thickness of the electrode in the compaction design area changes continuously from 0.134mm to 0.161mm and then to 0.134mm; the cathode electrode compaction range is 0.3g / cm 3 The thickness of the pole piece in the compaction design area changes continuously from 0.213mm to 0.191mm and then to 0.213mm.

[0187] The soaking time of the assembled battery cells was tested using the same testing method as in Example 1. The test results are shown in Table 1.

[0188] Example 12:

[0189] The same electrode formulation, coating process and battery cell assembly method as in Example 1 were used. The anode and cathode electrode compaction lengths were set to 6% to 80% of the range, and the anode electrode compaction range was 0.3 g / cm 3 The thickness of the electrode in the compaction design area changes continuously from 0.134mm to 0.161mm and then to 0.134mm; the cathode electrode compaction range is 0.3g / cm 3 The thickness of the pole piece in the compaction design area changes continuously from 0.213mm to 0.191mm and then to 0.213mm.

[0190] The soaking time of the assembled battery cells was tested using the same testing method as in Example 1. The test results are shown in Table 1.

[0191] Example 13:

[0192] The same electrode formula, coating process and battery cell assembly method as in Example 1 were used. The anode electrode compaction setting length interval was 6% to 80%, and the total compaction range was 0.3 g / cm 3 , a total of 3 gradients, each gradient density difference 0.1g / cm 3 The thickness of the electrode sheet in the compaction design area changes in steps from 0.134mm to 0.161mm and then to 0.134mm. The cathode electrode sheet is rolled using a roller press to a uniform thickness of 0.191mm. A partial schematic diagram of the cathode and anode electrode sheets of this embodiment, when paired together to form an electrode assembly, is shown in Figure 3.

[0193] The soaking time of the assembled battery cells was tested using the same testing method as in Example 1. The test results are shown in Table 1.

[0194] Example 14:

[0195] The same electrode formula, coating process and battery cell assembly method as in Example 1 were used. The cathode electrode compaction setting length interval was 6% to 80%, and the total compaction range was 0.3 g / cm 3 , a total of 3 gradients, each gradient density difference 0.1g / cm 3 The thickness of the electrode sheet in the compaction design area changes in steps from 0.213mm to 0.191mm and then to 0.213mm. The anode electrode sheet is rolled to a uniform thickness of 0.134mm using a roller press. A partial schematic diagram of the cathode and anode electrode sheets of this embodiment paired to form an electrode assembly is shown in Figure 4.

[0196] The soaking time of the assembled battery cells was tested using the same testing method as in Example 1. The test results are shown in Table 1.

[0197] Example 15:

[0198] The same electrode formula, coating process and battery cell assembly method as in Example 1 were used. The cathode electrode compaction setting length interval was 6% to 80%, and the total compaction range was 0.3 g / cm 3 , a total of 3 gradients, each gradient density difference 0.1g / cm 3 The thickness of the electrode in the compaction design area changes from 0.213mm to 0.191mm and then to 0.213mm in a step-by-step manner; the total compaction range of the anode electrode is 0.3g / cm 3 , a total of 3 gradients, each gradient density difference 0.1g / cm 3 The thickness of the pole piece in the compaction design area changes in steps from 0.134mm to 0.161mm and then to 0.134mm.

[0199] The soaking time of the assembled battery cells was tested using the same testing method as in Example 1. The test results are shown in Table 1.

[0200] Example 16:

[0201] The same electrode formulation, coating process and battery cell assembly method as in Example 1 were used. The anode electrode compaction setting length range was 6% to 80%, and the compaction range was 0.6 g / cm 3 The thickness of the anode electrode in the compaction design area changes continuously from 0.127mm to 0.188mm and then to 0.127mm; the cathode electrode is rolled to a constant thickness of 0.191mm using a roller press.

[0202] The soaking time of the assembled battery cells was tested using the same testing method as in Example 1. The test results are shown in Table 1.

[0203] Example 17:

[0204] The same electrode formulation, coating process and battery cell assembly method as in Example 1 were used. The anode electrode compaction setting length range was 6% to 80%, and the compaction range was 0.7 g / cm 3 The thickness of the anode electrode in the compaction design area changes continuously from 0.121mm to 0.188mm and then to 0.121mm; the cathode electrode is rolled to a constant thickness of 0.191mm using a roller press.

[0205] The soaking time of the assembled battery cells was tested using the same testing method as in Example 1. The test results are shown in Table 1.

[0206] Example 18:

[0207] The same electrode formulation, coating process and battery cell assembly method as in Example 1 were used. The cathode electrode compaction length range was 6% to 80%, and the compaction range was 0.8 g / cm 3The thickness of the cathode electrode in the compaction design area changes continuously from 0.240mm to 0.177mm and then to 0.240mm; the anode electrode is rolled to a constant thickness of 0.134mm using a roller press.

[0208] The soaking time of the assembled battery cells was tested using the same testing method as in Example 1. The test results are shown in Table 1.

[0209] Example 19:

[0210] The same electrode formulation, coating process and battery cell assembly method as in Example 1 were used. The cathode electrode compaction setting length range was 6% to 80%, and the compaction range was 0.9 g / cm 3 The thickness of the cathode electrode in the compaction design area changes continuously from 0.240mm to 0.172mm and then to 0.240mm; the anode electrode is rolled to a constant thickness of 0.134mm using a roller press.

[0211] The soaking time of the assembled battery cells was tested using the same testing method as in Example 1. The test results are shown in Table 1.

[0212] Comparative Example 1:

[0213] The same electrode sheet formula, coating process and battery cell assembly method as in Example 1 were used. The anode electrode sheet was rolled to a uniform thickness of 0.134 mm using a roller press; the cathode electrode sheet was rolled to a uniform thickness of 0.191 mm using a roller press.

[0214] The soaking time of the assembled battery cells was tested using the same testing method as in Example 1. The test results are shown in Table 1.

[0215] Comparative Example 2:

[0216] The same electrode formula, coating process and battery cell assembly method as in Example 1 were used. The anode electrode compaction setting length range was 0% to 100% of the full length of the electrode, and the compaction range was 0.3g / cm 3 Anode compaction design: The thickness of the electrode varies continuously from 0.134mm to 0.161mm from 0% to 25% of the total length; from 0.161mm to 0.134mm from 25% to 50% of the total length; from 0.134mm to 0.161mm from 50% to 75% of the total length; and from 0.161mm to 0.134mm from 75% to 100% of the total length. The cathode electrode is rolled using a roller press to a uniform thickness of 0.191mm.

[0217] The soaking time of the assembled battery cells was tested using the same testing method as in Example 1. The test results are shown in Table 1.

[0218] Table 1

[0219]

[0220]

[0221] In Example 1 of Table 1, the anode compaction design of "1.65~1.35~1.65" means that the compaction density of the anode active material layer from one end to the other end within the compaction design length range is 1.65 g / cm 3 Gradually changed to 1.35g / cm 3 Then gradually changed to 1.65g / cm 3 The thickness of the anode electrode sheet in the compaction design area is "0.134-0.161-0.134", indicating that the thickness of the anode active material layer gradually changes from 0.134 mm to 0.161 mm and then to 0.134 mm from one end to the other within the compaction design length range. The meaning of "~" in the compaction design and electrode sheet thickness data of other embodiments and comparative examples is similar to that of Example 1.

[0222] Comparing the test data of Example 1, Example 8, Example 11, and Comparative Example 1, it can be seen that by compacting the entire length of the anode active material layer on the anode pole piece, compacting the entire length (0% to 100%) of the cathode active material layer on the cathode pole piece, or compacting both the anode pole piece and the cathode pole piece, the electrolyte infiltration rate of the battery can be effectively increased and the infiltration time can be shortened. Among them, the electrolyte infiltration efficiency is higher and the infiltration time is shorter when both the anode pole piece and the cathode pole piece are compacted.

[0223] Comparing the test data of Examples 1 to 5, it can be seen that when the compaction design area is set to 6% to 80% of the full length of the pole piece, the infiltration time is shorter than the infiltration time when the compaction design area is the full length of the pole piece (0% to 100%), indicating that the compaction design area is 6% to 80% of the full length of the pole piece. The infiltration rate of the electrolyte can be better improved; further, when the compaction design area is set to 10% to 70% of the full length of the pole piece, the infiltration time is shorter than the infiltration time when the compaction design area is 6% to 80% of the full length of the pole piece. The compaction design area is 10% to 70% of the full length of the pole piece. The infiltration rate of the electrolyte can be further improved. In Examples 4 and 5, the range of the compaction design area is reduced to 20% to 50% and 30% to 40% of the full length of the pole piece, respectively. Compared with Examples 1 to 3, the infiltration time is extended instead.

[0224] Comparing Example 6 with Example 2, it can be seen that the compaction range within the compaction design area also affects the electrolyte infiltration rate. The test data from Example 12 shows that when the compaction design area is 6% to 80% of the total length of the electrode, compaction design is performed on both the anode and cathode electrodes, and the compaction range is set within an appropriate range, the electrolyte infiltration rate can be significantly increased and the infiltration time can be significantly shortened. The infiltration time in Example 12 is only 390 minutes.

[0225] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. An anode electrode, characterized in that: The invention comprises an anode current collector and an anode active material layer provided on the surface of the anode current collector, wherein the anode active material layer has a first compaction design area; in the first compaction design area, the compaction density of the anode active material layer first gradually decreases and then gradually increases along the extension direction of the electrode piece.

2. The anode plate according to claim 1, characterized in that: The first compaction design area covers the entire length of the anode electrode; Alternatively, the first compaction design area is from 6% to 80% of the total length of the anode pole piece; optionally, the first compaction design area is from 10% to 70% of the total length of the anode pole piece.

3. The anode plate according to claim 1 or 2, characterized in that: In the first compaction design area, the compaction density of the anode active material layer changes continuously along the extension direction of the anode electrode sheet.

4. The anode plate according to claim 3, characterized in that: In the first compaction design area, the difference between the maximum and minimum compaction density of the anode active material layer along the extension direction of the anode electrode is 0.01 g / cm 3 ~1.00g / cm 3 ; Optionally, within the first compaction design area, the difference between the maximum and minimum compaction density of the anode active material layer along the extension direction of the anode electrode sheet is 0.01 g / cm 3 ~0.60g / cm 3 .

5. The anode plate according to any one of claims 1 to 4, characterized in that: Along the extension direction of the anode electrode sheet, the compaction density of the anode active material layer at both ends of the first compaction design area and the compaction density of the anode active material layer outside the first compaction design area change continuously.

6. The anode plate according to claim 1 or 2, characterized in that: In the first compaction design area, the compaction density of the anode active material layer changes in a gradient along the extension direction of the anode electrode sheet.

7. The anode plate according to claim 6, characterized in that: In the first compaction design area, the number of gradients of compaction density variation of the anode active material layer is 3 to 15, and optionally, the compaction density difference between adjacent gradients is 0.01 g / cm 3 ~0.30g / cm 3 .

8. The anode plate according to any one of claims 1 to 7, characterized in that: In the first compaction design region, the length of the region where the compaction density of the anode active material layer continuously decreases is equal to the length of the region where the compaction density continuously increases.

9. A cathode electrode, characterized in that: It includes a cathode current collector and a cathode active material layer arranged on the surface of the cathode current collector, and the cathode active material layer has a second compaction design area; in the second compaction design area, the compaction density of the cathode active material layer first gradually increases and then gradually decreases along the extension direction of the cathode electrode.

10. The cathode plate according to claim 9, characterized in that: The second compaction design area covers the entire length of the cathode electrode; Alternatively, the second compaction design area is from 6% to 80% of the total length of the cathode electrode; optionally, the second compaction design area is from 10% to 70% of the total length of the cathode electrode.

11. The cathode plate according to claim 9 or 10, characterized in that: In the second compaction design area, the compaction density of the cathode active material layer changes continuously along the extension direction of the cathode electrode sheet.

12. The cathode plate according to claim 11, characterized in that: In the second compaction design area, the difference between the maximum and minimum compaction density of the cathode active material layer along the extension direction of the cathode electrode is 0.01 g / cm 3 ~1.50g / cm 3 ; Optionally, within the second compaction design area, the difference between the maximum and minimum compaction density of the cathode active material layer along the extension direction of the cathode electrode is 0.01 g / cm 3 ~0.80g / cm 3 .

13. The cathode plate according to any one of claims 9 to 12, characterized in that: Along the extension direction of the cathode electrode sheet, the compaction density of the cathode active material layer at both ends of the second compaction design area and the compaction density of the cathode active material layer outside the second compaction design area change continuously.

14. The cathode plate according to claim 9, characterized in that: In the second compaction design area, the compaction density of the cathode active material layer changes in a gradient along the extension direction of the cathode electrode.

15. The cathode plate according to claim 14, characterized in that: In the second compaction design area, the number of gradients of compaction density change of the cathode active material layer is 3 to 20, and optionally, the compaction density difference between adjacent gradients is 0.01 g / cm 3 ~0.50g / cm 3 .

16. The cathode plate according to any one of claims 9 to 15, characterized in that: In the second compaction design region, the length of the region where the compaction density of the cathode active material layer continuously increases is equal to the length of the region where the compaction density continuously decreases.

17. An electrode assembly, characterized in that: It comprises an anode electrode piece and a cathode electrode piece, wherein the anode electrode piece is the anode electrode piece according to any one of claims 1 to 8 and / or the cathode electrode piece is the cathode electrode piece according to any one of claims 9 to 16.

18. The electrode assembly according to claim 17, characterized in that The anode electrode plate is the anode electrode plate described in any one of claims 1 to 8, the cathode electrode plate is the cathode electrode plate described in any one of claims 9 to 16, and the first compression design area on the anode electrode plate corresponds to the position of the second compression design area on the cathode electrode plate.

19. The electrode assembly according to claim 17 or 18, characterized in that: The electrode assembly is a cylindrical electrode assembly formed by stacking and winding the anode electrode sheet and the cathode electrode sheet.

20. A battery, characterized in that: It comprises a shell, an electrode assembly and an electrolyte, wherein the electrode assembly comprises the electrode assembly according to any one of claims 17 to 19, the electrode assembly is accommodated in the inner cavity of the shell, and the electrolyte is accommodated in the inner cavity of the shell and infiltrates the electrode assembly.

21. An electrical device, characterized in that: Comprising the battery of claim 20.

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