Electrode sheet, battery, and vehicle

Abstract

An electrode sheet, a battery, and a vehicle. The electrode sheet comprises a current collector, an active material layer, and a tab, wherein the active material layer covers the current collector; the tab is connected to the current collector; Y=(Z×m) / (n×100,000) is defined, wherein Y represents the rate comprehensive influence characteristic of the electrode sheet, Z represents a preset path distance that electrons in the active material layer flow to the tab, the preset path distance is a greater value in the length direction or the width direction of the current collector, m represents the surface density of the electrode sheet, n represents the number of tabs, and 0.14≤Y≤3.2 is satisfied.

Description

Electrodes, batteries, and vehicles

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on November 30, 2023, with application number 202311641468.4 and application name “Electrode, Battery and Vehicle”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of battery technology, and in particular to a pole piece, a battery and a vehicle. Background Art

[0003] In recent years, batteries have become increasingly intertwined with human production and daily life, playing a crucial role in today's wave of electric vehicles and intelligent energy storage. Rate performance is a key consideration for batteries. For existing battery electrochemical systems, achieving high rate performance requires either reducing the battery's areal density or compaction density, adopting a multi-tab lead-out method, or reducing the length of the electrode. In summary, the overall design approach and goal is to ensure that the diffusion and transmission paths of ions and electrons in the battery are short and the diffusion difficulty is low.

[0004] However, in order to obtain batteries with high rate characteristics, existing technologies often lead to excessive design of the electrode sheets. For example, excessively reducing the surface density leads to a decrease in the overall energy density of the battery; or using multiple tabs to lead out and reducing the length of the electrode leads to an increase in the use of structural parts in the package, which in turn leads to a decrease in the mass energy density of the package. This is not only not conducive to improving the rate performance of the battery, but also results in a waste of resources. Therefore, how to comprehensively consider the relationship between the above three dimensions in the design of the electrode to improve the rate performance of the battery has become the key.

[0005] Summary of the Invention

[0006] The purpose of this application is to provide a pole piece, a battery and a vehicle to solve the problem of reduced rate performance caused by excessive pole piece design.

[0007] To achieve the purpose of this application, this application provides the following technical solutions:

[0008] In a first aspect, the present application provides a pole piece, comprising a current collector, an active material layer and a pole tab; wherein the active material layer is covered on the current collector; the pole tab is connected to the current collector; Y = (Z×m) / (n×100000) is defined; wherein Y is the comprehensive rate influence characteristic of the pole piece, Z is the preset path distance for the electrons in the active material layer to flow to the pole tab, the preset path distance is the larger value in the length direction or the width direction of the current collector, m is the surface density of the pole piece, and n is the number of the pole tabs; satisfying: 0.14≤Y≤3.2.

[0009] In one embodiment, Y satisfies: 1≤Y≤2.

[0010] In one embodiment, Z satisfies: 0 nm<Z≤1000 nm.

[0011] In one embodiment, m satisfies: 300 g / m 2 ≤m≤600g / m 2 .

[0012] In one implementation, n satisfies: 1≤n≤5.

[0013] In one embodiment, the tab is connected to the wide side of the current collector, the wide side of the current collector is less than or equal to the long side, and Z is the farthest distance that electrons in the active material layer flow to the tab in the length direction of the current collector.

[0014] In one embodiment, the tab is connected to the long side of the current collector, the wide side of the current collector is smaller than the long side, and Z is the farthest distance that electrons in the active material layer flow to the tab in the length direction of the current collector.

[0015] In one embodiment, there are multiple pole tabs, and the multiple pole tabs are arranged at equal intervals, and the wide side size of the current collector is less than half of the distance between two adjacent pole tabs, and Z is half of the distance between two adjacent pole tabs.

[0016] In one embodiment, the plurality of electrode tabs include two first electrode tabs and at least one second electrode tab, the second electrode tab is located between the two first electrode tabs, and when the distance from the first electrode tab to the wide side of the current collector is greater than or equal to half the distance from the first electrode tab to the second electrode tab, Z is the distance from the first electrode tab to the wide side of the current collector.

[0017] In a second aspect, the present application further provides a battery, comprising a separator, a positive electrode sheet and a negative electrode sheet, wherein the positive electrode sheet and / or the negative electrode sheet is the sheet described in the first aspect.

[0018] In a third aspect, the present application further provides a vehicle, comprising the battery described in the second aspect.

[0019] In order to reduce the phenomenon of reduced rate performance caused by excessive electrode design, this application provides a high-rate battery electrode. By defining the three dimensions of the electrode surface density, the distance of the electron conduction path, and the setting method of the electrode ear with a definition formula, a type of high-rate electrode can be comprehensively designed.

[0020] By limiting Y to the range of 0.14 to 3.2, the electrode can achieve excellent rate characteristics without causing over-design and reducing the energy density of the battery. When the Y value is less than 0.14, it indicates that the electron (or ion) diffusion in the electrode has reached its limit, and further shortening will not significantly optimize the rate characteristics; when the Y value is greater than 3.2, it indicates that the electron (or ion) diffusion path in the electrode is long and there are no multiple tabs for simultaneous extraction. Most electrons (or ions) in the active material layer cannot be effectively extracted through the tabs, resulting in poor rate performance of the electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the implementation methods of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the implementation methods or the description of the prior art. Obviously, the drawings described below are only some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] FIG1 is a schematic diagram of a cross-sectional structure of a pole piece according to an embodiment;

[0023] FIG2 is a schematic top view of a structure in which a tab is connected to a pole piece on a wide side in accordance with an embodiment;

[0024] FIG3 is a schematic top view of a structure in which a single tab is connected to a pole piece on a long side in one embodiment;

[0025] FIG4 is a schematic top view of a structure in which a single tab is connected to a pole piece on a long side in another embodiment;

[0026] FIG5 is a schematic top view of a structure in which a single tab is connected to a pole piece on a long side in yet another embodiment;

[0027] FIG6 is a schematic top view of a structure in which a plurality of tabs are connected to a pole piece on a long side in one embodiment;

[0028] FIG7 is a schematic top view of a structure in which a plurality of tabs are connected to a pole piece on a long side in another embodiment.

[0029] Description of reference numerals:

[0030] 100-pole piece, 1-current collector, 2-active material layer, 3-ear. DETAILED DESCRIPTION

[0031] The following will be combined with the accompanying drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0032] It should be noted that when a component is referred to as being "fixed to" another component, it may be directly on the other component or there may be an intermediate component. When a component is referred to as being "connected to" another component, it may be directly connected to the other component or there may be an intermediate component.

[0033] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by those skilled in the art to which this application belongs. The terms used in this specification are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" as used in this application includes any and all combinations of one or more of the relevant listed items.

[0034] The following describes some embodiments of the present application in detail with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features therein may be combined with each other.

[0035] The present application provides a pole piece 100 , please refer to FIG1 , which is used in a battery. The pole piece 100 includes a current collector 1 , an active material layer 2 and a pole tab 3 , wherein the active material layer 2 covers the current collector 1 ; the pole tab 3 is connected to the current collector 1 .

[0036] Optionally, the current collector 1 includes a wide side and a long side, wherein the wide side is an edge extending along the width direction and the long side is an edge extending along the length direction. The current collector 1 also includes a first surface and a second surface opposite to each other, wherein the first surface and / or the second surface is used to arrange the active material layer 2.

[0037] Optionally, the current collector 1 may be a foam metal mesh, a metal film material, etc., specifically including any one of copper foil and aluminum foil.

[0038] Optionally, the shape of the current collector 1 can be rectangular, square, elliptical, etc., without specific limitation.

[0039] Optionally, the active material layer 2 covers the first and / or second surfaces of the current collector 1. Preferably, to ensure the energy density of the electrode 100, the active material layer can cover as much of the first and / or second surfaces as possible, preferably completely.

[0040] Optionally, the active material layer 2 may include a positive electrode active material, a binder, and a conductive agent. The binder may include one or more of polyvinylidene chloride, soluble polytetrafluoroethylene, styrene-butadiene rubber, hydroxypropyl methylcellulose, methylcellulose, carboxymethyl cellulose, polyvinyl alcohol, acrylonitrile copolymer, sodium alginate, chitosan, and chitosan derivatives. The conductive agent may include one or more of graphite, carbon black, acetylene black, graphene, carbon fiber, C60, and carbon nanotubes.

[0041] Optionally, the slurry for making the active material layer 2 further includes a solvent, which can be selected from one or more of N-methylpyrrolidone (NMP), dimethylformamide (DMF), diethylformamide (DEF), water, and alcohols. Of course, the amount of solvent used in the slurry is not particularly limited, as long as the amount of solvent used satisfies the fluidity and uniformity of the slurry coating.

[0042] Optionally, as shown in FIG2 and FIG3 , the tab 3 is connected to the current collector 1 , specifically to the wide side (the wide side is marked with H in the figure) and / or the long side (the long side is marked with L in the figure) of the current collector 1 .

[0043] Optionally, the tab 3 can be formed separately from the current collector 1 and then connected together by bonding or other methods. Of course, in other embodiments, the tab 3 can also be an integrated structure with the current collector 1, and the tab 3 is a structure formed by cutting copper foil or aluminum foil.

[0044] Optionally, the electrode sheet 100 provided in the present application can be used in a laminated battery or a wound battery. Therefore, the specific dimensions of the long side and the wide side are not limited, and the long side can be larger than the wide side, or the wide side can be larger than the long side.

[0045] In one embodiment, the pole piece 100 has the following definition: Y = (Z×m) / (n×100000); wherein Y is the comprehensive rate influence characteristic of the pole piece 100, Z is the preset path distance for the electrons in the active material layer 2 to flow to the pole tab 3, the preset path distance is the larger value in the length direction or the width direction of the current collector 1, m is the surface density of the pole piece 100, and n is the number of pole tabs 3; satisfying: 0.14≤Y≤3.2.

[0046] Specifically, the rate-comprehensive impact characteristic Y of the electrode piece 100 is comprehensively defined by three dimensions: the distance of the electron conduction path in the electrode piece 100, the surface density of the electrode piece 100, and the arrangement of the tabs 3. The above three dimensions also have an impact on the rate performance of the electrode piece 100.

[0047] Wherein, Z is the preset path distance for electrons in the active material layer 2 to flow to the tab 3, and the preset path distance is the larger value in the length direction or the width direction of the current collector 1. It should be explained that, as shown in Figures 2 and 3, when the current collector 1 is rectangular, the tab 3 can be connected to the wide side or the long side of the current collector 1. The wide side is the side length of the current collector 1 in the width direction, and the long side is the side length of the current collector 1 in the length direction.

[0048] In this case, the movement directions of electrons in the active material layer 2 may include two types, one is moving along the wide side (i.e., the width direction) to the pole tab 3, and the other is moving along the long side (i.e., the length direction) to the pole tab 3. The distance that the electrons move along the wide side to the pole tab 3 may be ZH, and the distance that the electrons move along the long side to the pole tab 3 may be ZL. As shown in Figure 2, when the pole tab 3 is connected to the wide side, ZH is actually the distance that the electrons in the active material layer 2 at the long side of the current collector 1 move to the pole tab 3, and ZL is actually the distance that the electrons in the active material layer 2 at the wide side of the current collector 1 move to the pole tab 3. Therefore, Z in the above definition is actually the largest one between ZL and ZH. As shown in Figure 2, in this pole piece 100, Z in the definition is actually ZL.

[0049] Wherein, m is the surface density of the pole piece 100. Optionally, m is the double-sided surface density of the pole piece 100.

[0050] Where n is the number of tabs 3. Optionally, the number of tabs 3 should be related to the size of the pole piece 100. Taking a wound battery as an example, when the length of the current collector 1 is greater than the width, multiple spaced tabs 3 can be sequentially arranged along the long side of the current collector 1 to meet the requirements of a wound battery.

[0051] By limiting Y to the range of 0.14 to 3.2, the electrode 100 can achieve excellent rate characteristics without causing overdesign and reducing the energy density of the battery. When the Y value is less than 0.14, it indicates that the electron (or ion) diffusion in the electrode 100 has reached its limit, and further shortening will not significantly improve the rate characteristics. When the Y value is greater than 3.2, it indicates that the electron (or ion) diffusion path in the electrode 100 is long and there are no multiple tabs 3 for simultaneous extraction. Most electrons (or ions) in the active material layer 2 cannot be effectively extracted through the tabs 3, resulting in poor rate performance of the electrode 100.

[0052] Optionally, Y may also satisfy the range: 1≤Y≤2.

[0053] In order to reduce the phenomenon of low rate performance optimization caused by excessive design of the electrode 100, the present application provides a high-rate battery electrode. By defining the three dimensions of the surface density of the electrode 100, the distance of the electron conduction path and the setting method of the electrode ear 3 with a definition formula, a type of high-rate electrode 100 can be comprehensively designed.

[0054] In one embodiment, Z satisfies: 0 nm < Z ≤ 1000 nm. Specifically, the value of Z can be 100 mm, 200 mm, 300 mm, 400 mm, 500 mm, 600 mm, 700 mm, 800 mm, 900 mm, or 1000 mm.

[0055] Optionally, Z satisfies: 0 nm < Z ≤ 900 nm, or 100 nm ≤ Z ≤ 1000 nm, or 0 nm < Z ≤ 800 nm, or 200 nm ≤ Z ≤ 800 nm, or 0 nm < Z ≤ 700 nm, or 0 nm < Z ≤ 600 nm, or 300 nm ≤ Z ≤ 700 nm. Preferably, Z satisfies: 0 nm < Z ≤ 700 nm.

[0056] The maximum distance Z for the electrons in the active material layer to flow to the tab 3 is set to meet the above range. In fact, it is to ensure that the electrons have an appropriate moving distance and avoid the moving distance being too long or too short, so that Z can be used in conjunction with the above definition to limit the other two parameter indicators. When the moving distance of the electrons is too short, the Y value will be too small, so that the rate performance of the pole piece 100 cannot be improved through optimization; if the above Y value needs to be met, the compaction density of the pole piece 100 needs to be set too high, or the number of the tabs 3 is too many and too dense, resulting in an increase in the design difficulty of the pole piece 100 and an increase in the production difficulty, which is not conducive to industrial production. When the moving distance of the electrons is too long, the Y value will be too large, so that the rate performance of the pole piece 100 is poor; if the above Y value needs to be met, the compaction density of the pole piece 100 needs to be set too low, or the number of the tabs 3 is too few and too sparse, which is not conducive to improving the energy density of the battery and is not conducive to achieving the function of fast charging and discharging.

[0057] Furthermore, satisfying the above-mentioned range of Z is also conducive to designing the size of the current collector 1. It is understandable that the actual size of Z will not exceed the size of the long side or the wide side, that is, in any pole piece 100, the maximum possible size of Z is the size of the long side or the wide side. When the Z value is too small (that is, when the electron movement distance is too short), the size of the pole piece 100 will be designed to be too narrow; when the Z value is too large (that is, when the electron movement distance is too long), the size of the pole piece 100 will be designed to be too wide; both of the above are not conducive to the actual production and use of the pole piece 100.

[0058] In one embodiment, m satisfies: 300 g / m 2 ≤m≤600g / m2 Specifically, the value of m can be 300g / m 2 , 350g / m 2 , 400g / m 2 , 450g / m 2 , 500g / m 2 , 550g / m 2 , 600g / m 2 .

[0059] Optional, m meets: 300g / m 2 ≤m≤550g / m 2 , or 350g / m 2 ≤m≤600g / m 2 , or 350g / m 2 ≤m≤550g / m 2 , or 300g / m 2 ≤m≤500g / m 2 , or 400g / m 2 ≤m≤500g / m 2 .

[0060] The surface density m of the electrode 100 is set to meet the above range, so that m can be used to limit the other two parameter indicators by coordinating with the above definition. When the surface density of the electrode 100 is too small, the Y value will be too small, so that the rate performance of the electrode 100 cannot be improved through optimization; if the above Y value needs to be met, the number of the pole tabs 3 will be too small or the moving distance of the electrons will be too large, which is not conducive to improving its rate performance and will also make the overall energy density of the battery too low. When the surface density of the electrode 100 is too large, the Y value will be too large, so that the rate performance of the electrode 100 is poor; if the above Y value needs to be met, the number of the pole tabs 3 will be too small or the moving distance of the electrons will be too small, which increases the difficulty of process preparation.

[0061] In one embodiment, when the electrode 100 is a positive electrode, the compaction density of the electrode 100 is 2.2 g / cm 3 ~3.6g / cm 3 Specifically, the compacted density can be 2.2g / cm 3 , 2.3g / cm 3 , 2.4g / cm 3 , 2.5g / cm 3 , 2.6g / cm 3 , 2.7g / cm 3 , 2.8g / cm 3 , 2.9g / cm 3 , 3.0g / cm 3 , 3.1g / cm 3 、3.2g / cm3 、3.2g / cm 3 , 3.3g / cm 3 、3.4g / cm 3 , 3.5g / cm 3 、3.6g / cm 3 .

[0062] Optional, compacted density 2.2g / cm 3 ~3.2g / cm 3 , or 2.4g / cm 3 ~3.6g / cm 3 , or 2.2g / cm 3 ~3.0g / cm 3 , or 2.5g / cm 3 ~3.5g / cm 3 , or 2.5g / cm 3 ~3.0g / cm 3 .

[0063] In one embodiment, when the electrode 100 is a negative electrode, the compaction density of the electrode 100 is 1.2 g / cm 3 ~1.8g / cm 3 Specifically, the compacted density can be 1.2g / cm 3 , 1.3g / cm 3 , 1.4g / cm 3 , 1.5g / cm 3 , 1.6g / cm 3 , 1.7g / cm 3 , 1.8g / cm 3 .

[0064] It can be understood that the compaction density of the pole piece 100 is related to the surface density m of the pole piece 100 , so ensuring that the compaction density of the pole piece 100 is within the above range can further ensure that the surface density m of the pole piece 100 is within an appropriate range.

[0065] In one embodiment, n satisfies: 1≤n≤5. Specifically, the value of n can be 1, 2, 3, 4, or 5. Optionally, n satisfies: 1≤n≤4, or 1≤n≤3, or 2≤n≤5, or 2≤n≤4, or 3≤n≤5.

[0066] The number n of the tabs 3 is set to meet the above range, so that n can be used to limit the other two parameter indicators by coordinating with the above definition. When the number of tabs 3 is too small, the Y value will be too large, which will result in poor rate performance of the pole piece 100; if the above Y value needs to be met, it is necessary to reduce the moving distance of the electrons accordingly, or reduce the surface density of the pole piece 100, which is not conducive to improving its rate performance, and will also make the overall energy density of the battery too low. When the number of tabs 3 is too large, the Y value will be too small, which will result in the pole piece 100 using too many tabs 3, and additional structural parts will be added, resulting in waste of resources; if the above Y value needs to be met, it is necessary to increase the moving distance of the electrons accordingly, or increase the surface density of the pole piece 100, which increases the difficulty of process preparation.

[0067] In one embodiment, the tab 3 is connected to the wide side of the current collector 1, the wide side dimension of the current collector 1 is less than or equal to the long side dimension, the active material layer 2 is on the current collector 1, and Z is the farthest distance that electrons in the active material layer flow to the tab 3 in the length direction of the current collector 1.

[0068] Specifically, as shown in FIG2 , the tab 3 is connected to the wide side of the current collector 1; and the wide side of the current collector 1 is smaller than the long side (H<L). Therefore, based on the above embodiment, Z H <Z L , Z is the maximum distance that electrons in the active material layer flow to the tab 3 in the length direction of the current collector 1, that is, Z L .

[0069] Furthermore, as shown in FIG2 , the tab 3 is connected to the wide side of the current collector 1; and the wide side dimension of the current collector 1 is equal to the long side dimension (H=L). Therefore, based on the above embodiment, Z H <Z L , Z is the maximum distance that electrons in the active material layer flow to the tab 3 in the length direction of the current collector 1, that is, Z L .

[0070] Optionally, as shown in FIG2 , when there are multiple tabs 3 and all of them are connected to the wide side, the wide side size of the current collector 1 is smaller than the long side size (H<L). Therefore, compared with a single tab 3, Z H Further decrease, Z is still Z L .

[0071] In one embodiment, the tab 3 is connected to the long side of the current collector 1, the wide side dimension of the current collector 1 is smaller than the long side dimension, the active material layer 2 is on the current collector 1, and Z is the farthest distance that electrons in the active material layer flow to the tab 3 in the length direction of the current collector 1.

[0072] Specifically, as shown in FIG3 , the tab 3 is connected to the long side of the current collector 1 , and the wide side of the current collector 1 is smaller than the long side (H<L). H and Z L The following situations will occur, namely Z H <Z L 、Z H =Z L 、Z H >Z L .

[0073] For example, as shown in FIG3 , L=Z L1 +Z L2 +S, where S is the length of the tab 3, Z L1 is the distance that the electron moves on the left side of the tab 3, Z L2 is the distance the electron on the right moves. So, at Z L1 and Z L2 Any one of them is greater than Z H When Z>H in the definition, Z is the maximum distance that electrons in the active material layer flow to the tab 3 in the length direction of the current collector 1 (Z L1 or Z L2 ).

[0074] As shown in Figure 4, at Z L1 and Z L2 The largest one among them is also equal to Z H When Z=H in the definition, Z is the maximum distance that electrons in the active material layer flow to the tab 3 in the length direction of the current collector 1 (Z L ).

[0075] As shown in Figure 5, at Z L1 and Z L2 Both are less than Z H When Z<H in the definition, Z is the maximum distance that electrons in the active material layer flow to the tab 3 in the width direction of the current collector 1 (Z H Of course, in this embodiment, since Z<H, the longest path of electron transmission in the electrode 100 will change from Z to H, which means that the arrangement of more electrode tabs 3 will lead to an over-design of the electrode 100.

[0076] In one embodiment, the electrode tab 3 is connected to the long side of the current collector 1, the number of the electrode tabs 3 is multiple, the multiple electrode tabs 3 are arranged at equal intervals, and the wide side size of the current collector 1 is less than half of the distance between two adjacent electrode tabs 3, and Z is half of the distance between two adjacent electrode tabs 3, that is, the active material layer 2 is on the current collector 1, and the electron movement distance Z in the active material layer 2 is half of the distance between two adjacent electrode tabs 3.

[0077] Specifically, as shown in FIG6 , the number of tabs 3 is n, L=S×n+Z L1 +Z L2 +2×Z L3 ×(n-1). Among them, Z L1 Z is the distance from the leftmost tab 3 to the left wide side, L2 Z is the distance from the rightmost tab 3 to the right wide side, L3 It is half the distance between two adjacent tabs 3.

[0078] In Z L1 =Z L2 =Z L3 In the case of Z L3 Greater than or equal to Z H , Z in the above definition is Z L3 , which is the maximum distance that electrons in the active material layer flow to the tab 3 in the width direction of the current collector 1 .

[0079] In Z L1 and Z L2 Both are less than Z L3 In the case of Z L3 Greater than or equal to Z H , Z in the above definition is Z L3 , which is the maximum distance that electrons in the active material layer flow to the tab 3 in the width direction of the current collector 1 .

[0080] Of course, in Z L1 =Z L2 =Z L3 In the case of Z L1 Less than Z H , Z in the above definition is Z H , which is half the distance between two adjacent tabs 3. Of course, in this embodiment, since Z<H, the longest path of electron transmission in the pole piece 100 will change from Z to H, which means that the arrangement of more tabs 3 will lead to an over-design of the pole piece 100.

[0081] In one embodiment, as shown in Figures 6 and 7, the multiple pole tabs 3 include two first pole tabs and at least one second pole tab, and the second pole tab is located between the two first pole tabs. When the distance from the first pole tab to the wide side of the current collector 1 is greater than or equal to half the distance from the first pole tab to the second pole tab, Z is the distance from the first pole tab to the wide side of the current collector 1, that is, the active material layer 2 is on the current collector 1, and the electron movement distance Z in the active material layer 2 is the distance from the first pole tab to the wide side of the current collector 1.

[0082] Specifically, as shown in FIG7 , the number of tabs 3 is n, and the two first tabs are located on both sides of the current collector 1 in the length direction, and the second tab is located between the two first tabs. L1 =Z L2 >Z L3 In the case of Z L1 Greater than or equal to Z H , Z in the above definition is Z L1 , which is the distance from the first pole ear to the wide side of the current collector 1. For the second pole ear, it is still relatively Z L3 With Z H The size is as shown above and will not be repeated here.

[0083] Of course, when ZH is the maximum distance, the above-mentioned implementation can be referred to and will not be described in detail here.

[0084] In one embodiment, the tab 3 is connected to the long side of the current collector 1, the number of tabs 3 is multiple, and the multiple tabs 3 are arranged at non-equidistant intervals, then Z can be compared according to the above embodiment. L1 、Z L2 、Z L3 With Z H , and thus select the maximum value from among them and substitute it into the above definition for calculation.

[0085] In one embodiment, the present application further provides a battery comprising a separator, a positive electrode sheet, and a negative electrode sheet; wherein the positive electrode sheet and / or the negative electrode sheet are the electrode sheets in the above-mentioned embodiment. Specifically, the electrode sheet provided in the present application can be used as either a positive electrode sheet or a negative electrode sheet.

[0086] The diaphragm in the battery is located between the positive and negative electrodes, and is used for insulation and liquid retention between the positive and negative electrodes of the battery. It is contained in the battery casing together with the movement. There is no special limitation on the diaphragm, and you can choose various types of diaphragms used in batteries, such as PP, PE and other types of diaphragms.

[0087] Optionally, the battery further includes an electrolyte, and the electrolyte used in the battery is not limited. Various types of electrolytes used in ion batteries can be selected, and the electrolyte injection coefficient can be 2.0g / Ah to 4.5g / Ah.

[0088] Optionally, the battery may be a lithium-ion battery or a sodium-ion battery.

[0089] This application conducts a comprehensive design based on three dimensions: the surface density of the electrode in the battery, the distance of the electron conduction path, and the setting of the electrode ear; the three dimensions that affect the rate characteristics of the battery are comprehensively defined as Y; and by adjusting the Y value, the battery rate characteristics can be comprehensively managed and optimized.

[0090] In one embodiment, the present application also provides a vehicle, which includes the battery provided above.

[0091] The technical solution of this application is described in detail below through specific embodiments.

[0092] This application provides Examples 1 to 11, and Comparative Examples 1 to 8, a total of 19 battery groups, and tests are conducted on all 19 battery groups. Examples 1 to 10 use positive electrodes made with this solution, Example 11 uses negative electrodes made with this solution, Comparative Examples 1 to 7 use positive electrodes, and Comparative Example 8 uses negative electrodes.

[0093] The preparation method of the positive electrode sheet in the embodiment and the comparative example includes:

[0094] LFP was selected as the positive electrode active material, CNT and SP as the conductive materials, and PVDF as the binder material.

[0095] The positive electrode active material, porous positive electrode pre-physical and chemical material, CNT, SP, PVDF, and NMP are prepared into a slurry in a ratio of 100:12:0.3:2.5:55.

[0096] The slurry was evenly coated on a 15 μm thick conductive aluminum foil, baked, and die-cut to obtain the final positive electrode sheet. During die-cutting, the tab positions were reserved according to the requirements of each embodiment and comparative example. Furthermore, different lengths of positive electrode sheets needed to be die-cut according to different requirements. The tab or tabs in this experiment were not limited in their positions and could be on the same side or not.

[0097] The preparation method of the negative electrode sheet in the embodiment and the comparative example includes:

[0098] Graphite, sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber and water were mixed and stirred in a ratio of 100:1.5:3:130 to obtain a uniform slurry.

[0099] The slurry is evenly coated on an 8μm thick conductive copper foil, dried and rolled at 110°C, and then slit and die-cut to finally obtain the negative electrode sheet, which is the same as the positive electrode sheet. The corresponding tab positions and different lengths need to be reserved.

[0100] The preparation method of the battery in the embodiment and the comparative example includes:

[0101] The positive electrode sheets, negative electrode sheets and polypropylene separators are stacked in a Z-shaped stacking manner to assemble a lithium-ion battery core. The battery core is then hot-pressed and encapsulated in an aluminum-plastic film. The battery is obtained through processes such as liquid injection, aging, formation, aging, and capacity separation.

[0102] The performance tests of the batteries in the examples and comparative examples include:

[0103] (1) Capacity: At 25°C, fully charge the battery to 3.8V at a constant current and constant voltage of 0.33C. After standing, discharge the battery to 2.0V at a constant current of 0.33C. Repeat this three times. The third discharge capacity is recorded as C0. Multiply the third discharge capacity C0 by the average discharge voltage to obtain the energy density (Wh / kg).

[0104] (2) 0℃ / 25℃, 0.33C discharge capacity ratio: At 25℃, complete (1) test battery C0 capacity, at 25℃, charge to 3.8V with 0.33C0 and place, then discharge to 2.0V with 0.33C0 to obtain Q1; at 25℃, charge to 3.8V with 0.33C0, place the battery in a 0℃ environment for 4h, and then discharge to 2.0V with 0.33C0 to obtain Q2; Q2 / Q1 is the 0℃ / 25℃ 0.33C discharge capacity ratio.

[0105] Table 1 Coating ratios and battery parameters of various examples and comparative examples

[0106] It can be seen from the results of Example 1, Example 2 and Comparative Example 1 in Table 1 that, under the same surface density, the same number of tabs and the same tab position, when the length of the positive electrode sheet is increased (that is, the maximum distance Z for electron movement), the Y value will be increased. When it is increased to a certain limit, that is, when Y is greater than 3.2, its 0℃ / 25℃0.33C discharge capacity ratio will show a significant decrease. This is because the length of the Z value is the longest distance for electron transmission of the positive electrode sheet. Therefore, the increase in the longest distance will reduce its rate characteristics.

[0107] It can be seen from the results of Example 3 and Comparative Example 2 in Table 1 that, at the same Z, number and position of tabs, an increase in surface density will also lead to a decrease in rate characteristics. This is because when the surface density of the positive electrode increases, the length of its lithium ion diffusion path will be extended, which will in turn lead to a decrease in its rate characteristics. Therefore, when Z and n are the same, there is an upper limit to the surface density to achieve appropriate rate characteristics.

[0108] It can be seen from the results of Example 6, Example 10 and Comparative Example 2 in Table 1 that, for the same positive electrode plate length and m, increasing n and reducing its Z value can also ensure its rate characteristics.

[0109] From the results of Example 4, Comparative Example 3 and Comparative Example 4 in Table 1, it can be seen that under the same positive electrode sheet length and m, increasing n has an upper limit on the improvement of rate performance. In Comparative Examples 3 and 4, increasing n leads to a decrease in Z, and Z is less than H, so that the Y value is less than 0.14. Compared with Example 4, there is no obvious improvement in the rate characteristics, indicating that when the number of tabs n reaches a certain level, that is, when Z is reduced to a certain level, the improvement in rate characteristics will significantly decrease. A larger n will increase the mass of the non-lithium-intercalated active material in the battery, such as the mass of the current collector and the mass of the cover plate lead, thereby reducing the mass energy density. Secondly, when Z is less than H, the distance from the dressing point to the nearest tab will change from Z to H, which also indicates that there are too many tabs.

[0110] From the results of Example 9 and Comparative Example 7 in Table 1, it can be seen that when the width H is the same, the different number of tabs will lead to different Z, and the increase in the rate characteristic of n is not significant, but its energy density decreases significantly.

[0111] From the results of Example 5 and Comparative Example 5 in Table 1, it can be seen that when the positive electrode sheet length and Z are consistent, that is, the tab edge extension method is at the same surface density, reducing the positive electrode sheet length will reduce Z, thereby also improving its rate characteristics.

[0112] From the results of Example 7 and Comparative Example 6 in Table 1, it can be seen that although the difference in rate characteristics between the two is small, Y is less than 0.14, and its Z is less than H, indicating that there are too many tabs designed in this way. For the package, the increased inactive current collector and cover plate do not significantly improve the rate characteristics. Instead, the energy density will decrease, resulting in a design that is not worth the cost.

[0113] From the results of Example 8, Comparative Example 3, Comparative Example 4 and Comparative Example 6 in Table 1, it can be seen that when Z is less than H, the energy density will not decrease significantly only when Y is controlled to be greater than 0.14.

[0114] It can be seen from the results of Example 11 and Example 8 in Table 1 that the solution provided in this application is also applicable to negative electrode plates, and a battery with better performance can be obtained by adjusting the negative electrode plates to meet the formula provided in this application.

[0115] In the description of the embodiments of the present application, it should be noted that the orientation or positional relationship of terms such as "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", and "outside" are based on the orientation or positional relationship of the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0116] The above disclosure is only a preferred embodiment of the present application, and certainly cannot be used to limit the scope of rights of the present application. Ordinary technicians in this field can understand that all or part of the processes of the above embodiment and equivalent changes made in accordance with the claims of the present application are still within the scope covered by the present application.

Claims

1. A pole piece, wherein: include: current collector(1); An active material layer (2) covering the current collector (1); and A pole ear (3) connected to the current collector (1); Define Y=(Z×m) / (n×100000); Y is the comprehensive rate influence characteristic of the pole piece (100), Z is the preset path distance for the electrons in the active material layer (2) to flow to the pole lug (3), the preset path distance is the larger value in the length direction or the width direction of the current collector (1), m is the surface density of the pole piece (100), and n is the number of the pole lugs (3); satisfying: 0.14≤Y≤3.

2.

2. The pole piece according to claim 1, wherein: Y satisfies: 1≤Y≤2.

3. The pole piece according to claim 1 or 2, wherein: Z satisfies: 0nm<Z≤1000nm.

4. The pole piece according to any one of claims 1 to 3, wherein: m meets: 300g / m 2 ≤m≤600g / m 2 .

5. The pole piece according to any one of claims 1 to 4, wherein: n satisfies: 1≤n≤5.

6. The pole piece according to any one of claims 1 to 5, wherein: The pole ear (3) is connected to the wide side of the current collector (1), the wide side of the current collector (1) is smaller than or equal to the long side, and Z is the farthest distance that electrons in the active material layer (2) flow to the pole ear (3) in the length direction of the current collector (1).

7. The pole piece according to any one of claims 1 to 6, wherein: The pole ear (3) is connected to the long side of the current collector (1), the width of the current collector (1) is smaller than the long side, and Z is the farthest distance that electrons in the active material layer (2) flow to the pole ear (3) in the length direction of the current collector (1).

8. The pole piece according to claim 7, wherein: The number of the pole lugs (3) is multiple, the multiple pole lugs (3) are arranged at equal intervals, and the wide side dimension of the current collector (1) is less than half of the distance between two adjacent pole lugs (3), and Z is half of the distance between two adjacent pole lugs (3).

9. The pole piece according to claim 7 or 8, wherein: The plurality of pole ears include two first pole ears and at least one second pole ear, wherein the second pole ear is located between the two first pole ears, and when the distance from the first pole ear to the wide side of the current collector (1) is greater than or equal to half the distance from the first pole ear to the second pole ear, Z is the distance from the first pole ear to the wide side of the current collector (1).

10. A battery, wherein: The battery comprises a separator, a positive electrode sheet and a negative electrode sheet, wherein the positive electrode sheet and / or the negative electrode sheet is the electrode sheet according to any one of claims 1 to 9.

11. A vehicle, wherein: The vehicle includes the battery of claim 10.

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