Pole piece, battery and vehicle
By comprehensively designing the surface density, electron conduction path distance and electrode setting method of the battery electrode plate, defining Y=(Z×m)/(n×100000), the problem of reduction in rate performance caused by over-design of the electrode plate is solved, and the balance of high rate characteristics and energy density is achieved.
Patent Information
- Application Number
- CN202311641468.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-30
- Publication Date
- 2025-05-30
AI Technical Summary
When existing batteries pursue high-magnification characteristics, they often lead to over-design of the pole sheet, resulting in a decrease in the energy density of the battery and waste of resources.
By comprehensively designing the surface density of the electrode sheet, the distance of the electron conduction path and the setting of the electrode ear, Y=(Z×m)/(n×100000), where 0.14≤Y≤3.2 is used to optimize the comprehensive influence characteristics of the electrode sheet.
The high-magnification characteristics of the pole sheet are achieved, while avoiding the energy density reduction and resource waste caused by over-design.
Smart Images
Figure CN120072825A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of battery technology, and in particular to a pole piece, a battery and a vehicle. Background Art
[0002] In recent years, batteries have become increasingly closely related to human production and life, and they play an important role in today's wave of automotive electrification and intelligent energy storage. Among them, rate characteristics are a key consideration for batteries. For the existing electrochemical system of batteries, to obtain high rate characteristics, either the surface density or compaction density of the battery is reduced, or a multi-electrode lead-out method is adopted, or the length of the pole piece is reduced. In summary, the overall design idea and goal is to make the diffusion transmission path of ions and electrons in the battery short and the diffusion difficulty low.
[0003] However, in order to obtain batteries with high rate characteristics, the existing technologies mostly lead to excessive design of the pole pieces. For example, excessively reducing the surface density leads to a decrease in the overall energy density of the battery; or using multiple pole ears to lead out and reducing the length of the pole piece 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. Not only is it not conducive to improving the rate performance of the battery, it also causes a waste of resources. Therefore, how to comprehensively consider the relationship between the above three dimensions in the design of the pole piece to improve the rate performance of the battery has become the key. Summary of the invention
[0004] 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.
[0005] To achieve the purpose of this application, this application provides the following technical solutions:
[0006] In the first aspect, the present application provides a pole piece, comprising a current collector, an active material layer and a pole ear; wherein the active material layer is covered on the current collector; the pole ear is connected to the current collector; define Y = (Z×m) / (n×100000); 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 ear, 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 ears; satisfying: 0.14≤Y≤3.2.
[0007] In one implementation, Y satisfies: 1≤Y≤2.
[0008] In one implementation, Z satisfies: 0 nm<Z≤1000 nm.
[0009] In one embodiment, m satisfies: 300 g / m 2 ≤m≤600g / m2 。
[0010] In one embodiment, n satisfies: 1 ≤ n ≤ 5.
[0011] In one embodiment, the tab is connected to the wide side of the current collector, the size of the wide side of the current collector is less than or equal to the size of the long side, and Z is the maximum distance that electrons in the active material layer flow to the tab in the length direction of the current collector.
[0012] In one embodiment, the tab is connected to the long side of the current collector, the size of the wide side of the current collector is less than the size of the long side, and Z is the maximum distance that electrons in the active material layer flow to the tab in the length direction of the current collector.
[0013] In one embodiment, the number of the tabs is multiple, the multiple tabs are arranged at equal intervals, and the size of the wide side of the current collector is less than half of the distance between two adjacent tabs, and Z is half of the distance between two adjacent tabs.
[0014] In one embodiment, among the multiple tabs, there are two first tabs and at least one second tab, the second tab is located between the two first tabs, and when the distance from the first tab to the wide side of the current collector is greater than or equal to half of the distance from the first tab to the second tab, Z is the distance from the first tab to the wide side of the current collector.
[0015] In a second aspect, the present application further provides a battery, the battery includes a separator, a positive electrode plate and a negative electrode plate, wherein the positive electrode plate and / or the negative electrode plate is the electrode plate described in the first aspect.
[0016] In a third aspect, the present application further provides a vehicle, the vehicle includes the battery described in the second aspect.
[0017] In order to reduce the phenomenon of reduced rate performance caused by over-design of the electrode plate, the present application provides a high-rate battery electrode plate. By defining the surface density of the electrode plate, the distance of the electron conduction path, and the setting method of the tabs in three dimensions, a type of high-rate electrode plate can be comprehensively designed.
[0018] By limiting Y within the range of 0.14 to 3.2, the electrode plate can achieve excellent rate characteristics without causing over-design to reduce the energy density of the battery. When the value of Y is less than 0.14, it indicates that the diffusion of electrons (or ions) in the electrode plate has reached the limit, and further shortening cannot significantly optimize the rate characteristics; when the value of Y is greater than 3.2, it indicates that the diffusion path of electrons (or ions) in the electrode plate is long, and there are no multiple tabs for simultaneous extraction, and most electrons (or ions) in the active material layer cannot be effectively exported through the tabs, resulting in poor rate performance of the electrode plate. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.
[0020] Figure 1 is a schematic cross-sectional structure diagram of a pole piece of an embodiment;
[0021] Figure 2 is a schematic top view structure diagram of a pole piece with a tab connected to the wide side;
[0022] Figure 3 is a schematic top view structure diagram of a pole piece with a single tab connected to the long side of an embodiment;
[0023] Figure 4 is a schematic top view structure diagram of a pole piece with a single tab connected to the long side of another embodiment;
[0024] Figure 5 is a schematic top view structure diagram of a pole piece with a single tab connected to the long side of yet another embodiment;
[0025] Figure 6 is a schematic top view structure diagram of a pole piece with multiple tabs connected to the long side of an embodiment;
[0026] Figure 7 is a schematic top view structure diagram of a pole piece with multiple tabs connected to the long side of another embodiment.
[0027] Description of the reference numerals:
[0028] 100 - pole piece, 1 - current collector, 2 - active material layer, 3 - tab. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.
[0030] It should be noted that when a component is referred to as being "fixed to" another component, it can be directly on the other component or there can also be an intermediate component. When a component is considered to be "connected to" another component, it can be directly connected to the other component or there may be an intermediate component at the same time.
[0031] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. The terms used in this application in the specification are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in this application includes any and all combinations of one or more of the related listed items.
[0032] The following will describe in detail some embodiments of this application with reference to the accompanying drawings. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.
[0033] This application provides a pole piece 100. Please refer to Figure 1 , which is used in a battery. The pole piece 100 includes a current collector 1, an active material layer 2, and a tab 3. Among them, the active material layer 2 covers the current collector 1; the tab 3 is connected to the current collector 1.
[0034] Optionally, the current collector 1 includes a wide side and a long side. Among them, the wide side is the edge extending in the width direction, and the long side is the edge extending in the length direction. The current collector 1 also includes opposite first and second surfaces, and the active material layer 2 is disposed on the first surface and / or the second surface.
[0035] Optionally, the current collector 1 can be a foam metal mesh, a metal film material, etc., specifically including any one of copper foil and aluminum foil.
[0036] Optionally, the shape of the current collector 1 can be rectangular, square, oval, etc., and no specific limitation is made.
[0037] Optionally, the active material layer 2 covers the first surface and / or the second surface of the current collector 1. Preferably, in order to ensure the energy density of the pole piece 100, the active material layer can cover as much of the first surface and / or the second surface as possible. It is best to cover completely.
[0038] Optionally, the active material layer 2 can include a positive electrode active material, a binder, and a conductive agent. Among them, the binder includes one or more of polyvinylidene chloride, soluble polytetrafluoroethylene, styrene-butadiene rubber, hydroxypropyl methylcellulose, methylcellulose, carboxymethylcellulose, polyvinyl alcohol, acrylonitrile copolymer, sodium alginate, chitosan, and chitosan derivatives. The conductive agent includes one or more of graphite, carbon black, acetylene black, graphene, carbon fiber, C60, and carbon nanotubes.
[0039] Optionally, the slurry for making the active material layer 2 further includes a solvent, and the solvent can be one or more of N-methylpyrrolidone (NMP), dimethylformamide (DMF), diethylformamide (DEF), water, and alcohols. Of course, the amount of the solvent used in the slurry is not particularly limited, and the amount of the solvent can meet the fluidity and uniformity of the slurry coating.
[0040] Optionally, as Figure 2 and Figure 3 shown, the tab 3 is connected to the current collector 1, and specifically, it can be connected to the wide side (the wide side is marked as H in the figure) and / or the long side (the long side is marked as L in the figure) of the current collector 1.
[0041] Optionally, the tab 3 can be separately fabricated and formed with the current collector 1, and then connected together by bonding or other means. Of course, in other embodiments, the tab 3 can also be an integral structure with the current collector 1, and the tab 3 is a structure formed by cutting a copper foil or an aluminum foil.
[0042] Optionally, the electrode sheet 100 provided in the present application can be used in a stacked battery or a wound battery. Therefore, the specific dimensions of the long side and the wide side above are not limited, and the dimension of the long side can be greater than that of the wide side, or the dimension of the wide side can be greater than that of the long side.
[0043] In one embodiment, the electrode sheet 100 has the following definition: Y = (Z × m) / (n × 100000); where Y is the comprehensive influence characteristic of the rate of the electrode sheet 100, Z is the preset path distance for electrons in the active material layer 2 to flow to the 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 areal density of the electrode sheet 100, and n is the number of tabs 3; it satisfies: 0.14 ≤ Y ≤ 3.2.
[0044] Specifically, the comprehensive influence characteristic Y of the rate of the electrode sheet 100 is comprehensively defined by three dimensions: the conduction path distance of electrons in the electrode sheet 100, the areal density of the electrode sheet 100, and the setting manner of the tab 3. The above three dimensions also have an impact on the rate performance of the electrode sheet 100.
[0045] Among them, 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 Figure 2 and Figure 3 shown, 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. Among them, the wide side is the side length in the width direction of the current collector 1, and the long side is the side length in the length direction of the current collector 1.
[0046] In this case, the moving direction of electrons in the active material layer 2 can include two types. One is to move along the wide side (i.e., the width direction) to the tab 3, and the other is to move along the long side (i.e., the length direction) to the tab 3. The distance that electrons move along the wide side to the tab 3 can be Z H , and the distance that electrons move along the long side to the tab 3 can be Z L . As Figure 2 shown, when the tab 3 is connected to the wide side, Z H is actually the distance that electrons in the active material layer 2 at the long side of the current collector 1 move to the tab 3, and Z L is actually the distance that electrons in the active material layer 2 at the wide side of the current collector 1 move to the tab 3. Therefore, Z in the above definition formula is actually the larger one of Z L and Z H . As Figure 2 shown, in this electrode sheet 100, Z in the definition formula is actually Z L .
[0047] Wherein, m is the areal density of the electrode sheet 100. Optionally, m is the double-sided areal density of the electrode sheet 100
[0048] Wherein, n is the number of tabs 3. Optionally, the number of tabs 3 should be related to the size of the electrode sheet 100. Taking a wound battery as an example, when the length of the current collector 1 is greater than the width, a plurality of spaced tabs 3 can be sequentially arranged on the long side of the current collector 1 to meet the requirements of the wound battery in turn
[0049] By limiting Y within the range of 0.14 to 3.2, the electrode sheet 100 can achieve excellent rate performance and will not cause over-design to reduce the energy density of the battery. When the value of Y is less than 0.14, it indicates that the diffusion of electrons (or ions) in the electrode sheet 100 has reached the limit, and further shortening cannot significantly optimize the rate performance; when the value of Y is greater than 3.2, it indicates that the diffusion path of electrons (or ions) in the electrode sheet 100 is long, and there are no multiple tabs 3 for simultaneous extraction, and most of the 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 sheet 100
[0050] Optionally, Y can also satisfy the range: 1 ≤ Y ≤ 2
[0051] In order to reduce the phenomenon of low rate performance optimization caused by over-design of the electrode sheet 100, the present application provides a high-rate battery electrode sheet. By defining the areal density of the electrode sheet 100, the distance of the electron conduction path, and the setting method of the tabs 3 in three dimensions, a type of high-rate electrode sheet 100 can be comprehensively designed
[0052] 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, 1000 mm.
[0053] 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.
[0054] Set the maximum distance Z for the electrons in the active material layer to flow to the tab 3 to satisfy the above range. Actually, it is to ensure that the electrons have a suitable moving distance and avoid the moving distance being too long or too short, so that Z can be used in combination with the above definition formula to limit the other two parameter indicators. When the moving distance of the electrons is too short, the value of Y will be too small, resulting in the rate performance of the electrode sheet 100 not being able to be improved by optimization; if the above Y value needs to be satisfied, it is necessary to set the compaction density of the electrode sheet 100 too high, or the number of tabs 3 is too large and too dense, resulting in an increase in the design difficulty of the electrode sheet 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 value of Y will be too large, resulting in poor rate performance of the electrode sheet 100; if the above Y value needs to be satisfied, it is necessary to set the compaction density of the electrode sheet 100 too low, or the number of tabs 3 is too small and too sparse, which is not conducive to improving the battery energy density and is not conducive to realizing the function of fast charging and discharging.
[0055] Furthermore, Z satisfying the above range is also conducive to designing the size of the current collector 1. It can be understood that the actual size of Z will not exceed the size of the long side or the wide side, that is, in any electrode sheet 100, the maximum situation where Z can appear is the size of the long side or the wide side. When the value of Z is too small (i.e., the moving distance of the electrons is too short), it will lead to a too narrow design of the size of the electrode sheet 100; when the value of Z is too large (i.e., the moving distance of the electrons is too long), it will lead to a too wide design of the size of the electrode sheet 100; the above are all not conducive to the actual production and use of the electrode sheet 100.
[0056] In one embodiment, m satisfies: 300 g / m 2 ≤ m ≤ 600 g / m 2 . Specifically, the value of m can be 300 g / m 2 、350 g / m 2 、400 g / m 2 、450 g / m 2 、500 g / m 2 、550 g / m 2, 600 g / m 2 .
[0057] Optionally, m satisfies: 300 g / m 2 ≤ m ≤ 550 g / m 2 , or 350 g / m 2 ≤ m ≤ 600 g / m 2 , or 350 g / m 2 ≤ m ≤ 550 g / m 2 , or 300 g / m 2 ≤ m ≤ 500 g / m 2 , or 400 g / m 2 ≤ m ≤ 500 g / m 2 .
[0058] Set the surface density m of the electrode tab 100 to satisfy the above range, so that m can limit the other two parameter indicators in cooperation with the above definition formula. When the surface density of the electrode tab 100 is too small, the Y value will be too small, resulting in the rate performance of the electrode tab 100 unable to be improved by optimization; if the above Y value needs to be satisfied, the number of the tabs 3 is too small or the moving distance of electrons is 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 tab 100 is too large, the Y value will be too large, resulting in poor rate performance of the electrode tab 100; if the above Y value needs to be satisfied, the number of the tabs 3 is too small or the moving distance of electrons is too small, increasing the difficulty of the process preparation.
[0059] In one embodiment, when the electrode tab 100 is a positive electrode tab, the tap density of the electrode tab 100 is 2.2 g / cm 3 ~3.6 g / cm 3 . Specifically, the tap density can be 2.2 g / cm 3 , 2.3 g / cm 3 , 2.4 g / cm 3 , 2.5 g / cm 3 , 2.6 g / cm 3 , 2.7 g / cm 3 , 2.8 g / cm 3 , 2.9 g / cm 3 , 3.0 g / cm 3 , 3.1 g / cm 3 , 3.2 g / cm 3 , 3.2 g / cm 3 , 3.3 g / cm 3 , 3.4 g / cm 3 , 3.5 g / cm 3 , 3.6 g / cm 3 .
[0060] Optionally, the compaction density is 2.2 g / cm 3 ~3.2 g / cm 3 、 or 2.4 g / cm 3 ~3.6 g / cm 3 、 or 2.2 g / cm 3 ~3.0 g / cm 3 、 or 2.5 g / cm 3 ~3.5 g / cm 3 、 or 2.5 g / cm 3 ~3.0 g / cm 3 。
[0061] In one embodiment, when the electrode sheet 100 is a negative electrode sheet, the compaction density of the electrode sheet 100 is 1.2 g / cm 3 ~1.8 g / cm 3 。 Specifically, the compaction density can be 1.2 g / cm 3 、 1.3 g / cm 3 、 1.4 g / cm 3 、 1.5 g / cm 3 、 1.6 g / cm 3 、 1.7 g / cm 3 、 1.8 g / cm 3 。
[0062] It can be understood that the compaction density of the electrode sheet 100 is related to the areal density m of the electrode sheet 100. Therefore, ensuring that the compaction density of the electrode sheet 100 is within the above range can further ensure that the areal density m of the electrode sheet 100 is within a suitable range.
[0063] In one embodiment, n satisfies: 1 ≤ n ≤ 5. Specifically, the value of n can be 1, 2, 3, 4, 5. Optionally, n satisfies: 1 ≤ n ≤ 4, or 1 ≤ n ≤ 3, or 2 ≤ n ≤ 5, or 2 ≤ n ≤ 4, or 3 ≤ n ≤ 5.
[0064] Set the number n of the tabs 3 to satisfy the above range, so that n can be used to limit the other two parameter indicators in cooperation with the above definition formula. When the number of the tabs 3 is too small, the value of Y will be too large, resulting in poor rate performance of the electrode sheet 100; if the above Y value needs to be satisfied, the moving distance of electrons needs to be correspondingly reduced, or the areal density of the electrode sheet 100 needs to be reduced, 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 the tabs 3 is too large, the value of Y will be too small, resulting in too many tabs 3 being used in the electrode sheet 100, an increase in additional structural components, and a waste of resources; if the above Y value needs to be satisfied, the moving distance of electrons needs to be correspondingly increased, or the areal density of the electrode sheet 100 needs to be increased, increasing the difficulty of the process preparation.
[0065] In one embodiment, the tab 3 is connected to the wide side of the current collector 1. The size of the wide side of the current collector 1 is less than or equal to the size of the long side. The active material layer 2 is on the current collector 1, and 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.
[0066] Specifically, as Figure 2 shown, the tab 3 is connected to the wide side of the current collector 1; and the size of the wide side of the current collector 1 is less than the size of the long side (H < L). Therefore, based on the above embodiment, Z H < Z L , where 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 .
[0067] Furthermore, as Figure 2 shown, the tab 3 is connected to the wide side of the current collector 1; and the size of the wide side of the current collector 1 is equal to the size of the long side (H = L). Therefore, based on the above embodiment, Z H < Z L , where 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 .
[0068] Optionally, as Figure 2 shown, when the number of tabs 3 is multiple and all are connected to the wide side, the size of the wide side of the current collector 1 is still less than the size of the long side (H < L). Therefore, compared with the case of a single tab 3, Z H is further reduced, and Z is still Z L .
[0069] In one embodiment, the tab 3 is connected to the long side of the current collector 1. The size of the wide side of the current collector 1 is less than the size of the long side. The active material layer 2 is on the current collector 1, and 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.
[0070] Specifically, as Figure 3 shown, the tab 3 is connected to the long side of the current collector 1, and the size of the wide side of the current collector 1 is less than the size of the long side (H < L). Therefore, based on the above embodiment, Z H and Z L will present the following situations, which are respectively Z H < Z L , Z H = Z L , Z H > Z L .
[0071] For example, as Figure 3 shown, L = Z L1 + ZL2 +S, where it can be seen that S is the length of tab 3, and Z L1 is the distance that electrons move to the left of tab 3, and Z L2 is the distance that electrons move to the right. Therefore, when either Z L1 or Z L2 is greater than Z H (i.e., Z > H in the defining formula), Z is the maximum distance that electrons in the active material layer flow to tab 3 in the length direction of current collector 1 (Z L1 or Z L2 ).
[0072] As Figure 4 shown, when the maximum value of Z L1 and Z L2 is also equal to Z H (i.e., Z = H in the defining formula), Z is the maximum distance that electrons in the active material layer flow to tab 3 in the length direction of current collector 1 (Z L ).
[0073] As Figure 5 shown, when both Z L1 and Z L2 are less than Z H (i.e., Z < H in the defining formula), Z is the maximum distance that electrons in the active material layer flow to tab 3 in the width direction of current collector 1 (Z H ). Of course, in this embodiment, since Z < H, the longest path of electron transmission in the electrode tab 100 will change from Z to H, which indicates that setting more tabs 3 will lead to over - design of the electrode tab 100.
[0074] In one embodiment, tab 3 is connected to the long side of current collector 1, the number of tabs 3 is multiple, the multiple tabs 3 are arranged at equal intervals, and the width dimension of current collector 1 is less than half of the distance between two adjacent tabs 3. Z is half of the distance between two adjacent tabs 3, that is, the active material layer 2 is on current collector 1, and the electron movement distance Z in the active material layer 2 is half of the distance between two adjacent tabs 3.
[0075] Specifically, as Figure 6 shown, the number of tabs 3 is n, L = S×n + Z L1 +Z L2 +2×Z L3 ×(n - 1). Wherein, Z L1 is the distance from the left - most tab 3 to the left - hand wide side, Z L2 is the distance from the right - most tab 3 to the right - hand wide side, and Z L3 is half of the distance between two adjacent tabs 3.
[0076] When Z L1=Z L2 =Z L3 In the case where, and Z L3 is greater than or equal to Z H , Z in the above defining formula is Z L3 , that is, the farthest distance that the electrons in the active material layer flow to the tab 3 in the width direction of the current collector 1.
[0077] In Z L1 and Z L2 are both less than Z L3 In the case where, and Z L3 is greater than or equal to Z H , Z in the above defining formula is Z L3 , that is, the farthest distance that the electrons in the active material layer flow to the tab 3 in the width direction of the current collector 1.
[0078] Of course, in the case where Z L1 =Z L2 =Z L3 In the case where, and Z L1 is less than Z H , Z in the above defining formula is Z H , that is, half of the distance between two adjacent tabs 3. 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 indicates that setting more tabs 3 will lead to over-design of the electrode 100.
[0079] In one embodiment, as Figure 6 and Figure 7 shown, among the multiple tabs 3, there are two first tabs and at least one second tab. The second tab is located between the two first tabs. When the distance from the first tab to the wide side of the current collector 1 is greater than or equal to half of the distance from the first tab to the second tab, Z is the distance from the first 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 tab to the wide side of the current collector 1.
[0080] Specifically, as Figure 7 shown, the number of tabs 3 is n, and the two first tabs are respectively located on the two sides of the current collector 1 far away in the length direction, and the second tab is located between the two first tabs. For the first tab, in the case where Z L1 =Z L2 >Z L3 In the case where, and Z L1 is greater than or equal to Z H , Z in the above defining formula is Z L1 , that is, the distance from the first tab to the wide side of the current collector 1. For the second tab, it is still to compare Z L3 with Z HThe size, as shown above, will not be elaborated further.
[0081] Of course, in the case where Z H is the maximum distance, the above-described embodiments can be referred to and will not be elaborated herein.
[0082] In one embodiment, the tab 3 is connected to the long side of the current collector 1, and the number of tabs 3 is multiple. The multiple tabs 3 are arranged at non-equidistant intervals, and then Z can be compared according to the above-described embodiment L1 、Z L2 、Z L3 and Z H in terms of size, and then the maximum value can be selected and substituted into the above-defined formula for calculation.
[0083] In one embodiment, the present application further provides a battery, which includes a separator, a positive electrode plate and a negative electrode plate; wherein, the positive electrode plate and / or the negative electrode plate are the electrode plates in the above-described embodiments. Specifically, the electrode plate provided by the present invention can be used as a positive electrode plate or a negative electrode plate.
[0084] The separator in the battery is located between the positive and negative electrodes and is used for insulation and liquid retention characteristics between the positive and negative electrodes of the battery. It is accommodated in the battery case together with the movement. The separator is not particularly limited and can be selected from various separators used in batteries, such as various separators such as PP and PE.
[0085] Optionally, the battery further includes an electrolyte, and the electrolyte used in the battery is not limited either. Various electrolytes used in ion batteries can be selected, and the injection coefficient of the electrolyte can be 2.0 g / Ah to 4.5 g / Ah.
[0086] Optionally, the battery can be a lithium-ion battery or a sodium-ion battery.
[0087] The present invention comprehensively designs the three dimensions of the surface density of the electrode plate in the battery, the distance of the electron conduction path, and the setting method of the tab; the three dimensions affecting the rate performance in the battery are comprehensively defined as Y; by regulating the Y value, the comprehensive control of the optimization of the battery rate performance can be carried out.
[0088] In one embodiment, the present application further provides a vehicle, which includes the battery provided above.
[0089] The technical solutions of the present invention will be described in detail below through specific embodiments.
[0090] The present application provides Examples 1-11 and Comparative Examples 1-8, a total of 19 groups of batteries, and tests the 19 groups of batteries. Among them, the positive electrode plates in Examples 1-10 are made by the present scheme, the negative electrode plate in Example 11 is made by the present scheme, the positive electrode plates in Comparative Examples 1-7 are used, and the negative electrode plate in Comparative Example 8 is used.
[0091] The preparation methods of the positive electrode plates in the examples and comparative examples include:
[0092] Select LFP as the positive electrode active material, CNT and SP as the conductive agent materials, and PVDF as the binder material.
[0093] Prepare a slurry by mixing the positive electrode active material, porous positive electrode pre-physicochemical material, CNT, SP, PVDF, and NMP in a ratio of 100:12:0.3:2.5:55.
[0094] Coat the slurry evenly on a 15-μm-thick conductive aluminum foil, bake and die-cut to obtain the final positive electrode plate. Among them, when die-cutting, reserve the tab positions according to the requirements of each example and comparative example. Secondly, it is necessary to die-cut positive electrode plates of different lengths according to different requirements. The tab or multi-tab positions in this experiment are not limited and can be on the same side or not on the same side.
[0095] The preparation methods of the negative electrode plates in the examples and comparative examples include:
[0096] Mix graphite, sodium carboxymethylcellulose (CMC), styrene-butadiene rubber, and water in a ratio of 100:1.5:3:130, and charge and mix them evenly by stirring to obtain a slurry.
[0097] Coat the slurry evenly on an 8-μm-thick conductive copper foil, dry and roll it at 110°C, and then finally obtain the negative electrode plate through slitting and die-cutting. Similar to the positive electrode plate, it is necessary to reserve the corresponding tab positions and different lengths.
[0098] The preparation methods of the batteries in the examples and comparative examples include:
[0099] Stack the above positive electrode plate, negative electrode plate, and polypropylene separator in a Z-shaped stacking manner to assemble a lithium-ion battery core. Subsequently, thermally press the battery core and encapsulate it in an aluminum-plastic film, and obtain the battery through processes such as liquid injection, aging, formation, aging, and grading.
[0100] The performance tests of the batteries in the examples and comparative examples include:
[0101] (1) Capacity: At 25°C, charge it to 3.8V with a constant current of 0.33C under constant voltage, let it stand, and then discharge it with a constant current of 0.33C to 2.0V. Repeat 3 times, and record the capacity released in the 3rd time as C0; multiply the average discharge voltage by the third discharge capacity C0 to obtain the energy density, with the unit Wh / kg.
[0102] (2) 0°C / 25°C, 0.33C discharge capacity ratio: At 25°C, complete the capacity test of battery C0 in (1). At 25°C, charge it to 3.8V at 0.33C0, let it stand, and then discharge it to 2.0V at 0.33C0 to obtain Q1; at 25°C, charge it to 3.8V at 0.33C0, place the battery in an environment of 0°C for 4 hours, and then discharge it to 2.0V at 0.33C0 to obtain Q2; Q2 / Q1 is the 0°C / 25°C 0.33C discharge capacity ratio.
[0103] Table 1 Coating ratios and battery parameters of each example and comparative example
[0104]
[0105]
[0106] From the results of Example 1, Example 2 and Comparative Example 1 in Table 1, it can be seen that under the same surface density, the same number of tabs and tab positions, when increasing the length of the positive electrode plate (i.e., increasing the maximum distance Z for electron movement), the Y value will increase. When it is increased to a certain limit, that is, when Y is greater than 3.2, the 0°C / 25°C 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 transport in this positive electrode plate. Therefore, the increase in the longest distance will lead to the decrease of its rate performance.
[0107] From the results of Example 3 and Comparative Example 2 in Table 1, it can be seen that when Z, the number of tabs and their positions are the same, the increase in surface density will also lead to the decrease of rate performance. 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 further lead to the decrease of its rate performance. Therefore, when Z and n are the same, to achieve appropriate rate performance conditions, there is an upper limit for the surface density.
[0108] From the results of Example 6, Example 10 and Comparative Example 2 in Table 1, it can be seen that for the same positive electrode plate length and m, increasing n and reducing its Z value can also ensure its rate performance.
[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 plate length and m, there is an upper limit for increasing n to improve the rate performance. In Comparative Example 3 and Comparative Example 4, after increasing n, Z decreases, and Z is less than H, resulting in Y value less than 0.14. Compared with Example 4, its rate performance has no obvious improvement, indicating that when the number of tabs n reaches a certain value, that is, when Z decreases to a certain value, the improvement amplitude of the rate performance will decrease significantly. And more n will increase the mass of inactive lithium-inserting substances in the battery, such as the mass of the current collector and the mass of the cover plate lead-out, etc., which will further reduce 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 too many tabs.
[0110] It can be seen from the results of Example 9 and Comparative Example 7 in Table 1 that when the width H is the same, the different numbers 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] It can be seen from the results of Example 5 and Comparative Example 5 in Table 1 that when the length of the positive electrode sheet is consistent with Z, that is, the tab edge lead-out method is at the same surface density, reducing the length of the positive electrode sheet will reduce Z, thereby also improving its rate characteristics.
[0112] It can be seen from the results of Example 7 and Comparative Example 6 in Table 1 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 pole ears designed in this way. For the package, the increased inactive current collector and cover plate do not significantly improve the rate characteristics, but the energy density will decrease, resulting in a design that is not worth the cost.
[0113] It can be seen from the results of Example 8, Comparative Example 3, Comparative Example 4 and Comparative Example 6 in Table 1 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 the present 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 the present 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 are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element 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] What is disclosed above is only a preferred embodiment of the present application, and it 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 implementing the above embodiment and equivalent changes made according to the claims of the present application are still within the scope covered by the present application.
Claims
1. A pole piece, characterized in that, it includes: a current collector; an active material layer covering the current collector; a tab connected to the current collector; define Y = (Z × m) / (n × 100000); where Y is the comprehensive influence characteristic of the rate of the pole piece, Z is the preset path distance for electrons in the active material layer to flow to the tab, the preset path distance is the larger value in the length direction or width direction of the current collector, m is the areal density of the pole piece, and n is the number of tabs; satisfy: 0.14 ≤ Y ≤ 3.
2.
2. The pole piece according to claim 1, characterized in that, Y satisfies: 1 ≤ Y ≤ 2.
3. The pole piece according to claim 1, characterized in that, Z satisfies: 0nm < Z ≤ 1000nm.
4. The pole piece according to claim 1, characterized in that, m satisfies: 300 g / m 2 ≤ m ≤ 600 g / m 2 .
5. The pole piece according to claim 1, characterized in that, n satisfies: 1 ≤ n ≤ 5.
6. The pole piece according to claim 1, characterized in that, the tab is connected to the wide side of the current collector, the size of the wide side of the current collector is less than or equal to the size of the long side, and Z is the maximum distance for electrons in the active material layer to flow to the tab in the length direction of the current collector.
7. The pole piece according to claim 1, characterized in that, the tab is connected to the long side of the current collector, the size of the wide side of the current collector is less than the size of the long side, and Z is the maximum distance for electrons in the active material layer to flow to the tab in the length direction of the current collector.
8. The pole piece according to claim 7, characterized in that, the number of tabs is multiple, the multiple tabs are arranged at equal intervals, and the size of the wide side of the current collector is less than half of the distance between two adjacent tabs, and Z is half of the distance between two adjacent tabs.
9. The pole piece according to claim 8, characterized in that, the multiple tabs include two first tabs and at least one second tab, the second tab is located between the two first tabs, when the distance from the first tab to the wide side of the current collector is greater than or equal to half of the distance from the first tab to the second tab, Z is the distance from the first tab to the wide side of the current collector.
10. A battery, characterized in that, the battery includes a separator, a positive pole piece and a negative pole piece, wherein the positive pole piece and / or the negative pole piece is the pole piece according to any one of claims 1-9.
11. A vehicle, characterized in that, the vehicle includes the battery according to claim 10.