Electrode sheet and preparation method therefor, battery, battery pack, and electric device

Abstract

The present application provides an electrode sheet and a preparation method therefor, a battery, a battery pack, and an electric device. The electrode sheet comprises an electrode current collector and an electrode coating layer located on the surface of at least one side of the electrode current collector, wherein the electrode coating layer comprises an electrode active material; and the electrode coating layer comprises oriented regions and non-oriented regions arranged alternately in a first direction, wherein the OI value of the oriented regions is lower than the OI value of the non-oriented regions, and the first direction intersects the thickness direction of the electrode coating layer.

Description

An electrode sheet, a preparation method thereof, a battery, a battery pack, and an electrical device

[0001] The present application claims priority to the Chinese patent application No. 202411075072.2, filed on August 6, 2024, and entitled "An electrode sheet, a preparation method thereof, a battery, a battery pack, and an electrical device", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the field of batteries, in particular to an electrode sheet, a preparation method thereof, a battery, a battery pack, and an electrical device. BACKGROUND

[0003] The electrode sheet is an important component of the battery, and the diffusion capacity of active ions such as lithium ions in the electrode sheet determines the charging rate of the battery (such as a power battery). By regulating the orientation degree of the electrode active material in the electrode sheet, the electrode active material is arranged in a direction that is beneficial to the embedding of active ions such as lithium ions into the electrode active material, which can promote the rapid transmission of active ions such as lithium ions in the electrode sheet, reduce the impedance of the electrode sheet, and improve the fast-charging capability and other performances of the battery. However, the directional arrangement of the electrode active material in the electrode sheet can exacerbate the expansion of the electrode active material during the charging and discharging process of the battery, and the electrode active material is prone to falling off and peeling off during the battery cycle process, thereby affecting the cycle stability and other performances of the battery. Therefore, how to reduce the impedance of the battery while ensuring the cycle stability of the battery is not affected is a technical problem to be solved by those skilled in the art. SUMMARY

[0004] The present application provides an electrode sheet, a preparation method thereof, a battery, a battery pack, and an electrical device, which can reduce the impedance of the battery and improve the cycle stability of the battery, and effectively overcome the defects of the prior art.

[0005] In one aspect of the present application, an electrode sheet is provided, which comprises an electrode current collector and an electrode coating on at least one side surface of the electrode current collector, the electrode coating comprising an electrode active material; the electrode coating comprises orientation regions and non-orientation regions arranged alternately in a first direction, the OI value of the orientation regions is less than the OI value of the non-orientation regions, and the first direction intersects the thickness direction of the electrode coating.

[0006] According to an embodiment of the present application, the ratio of the OI value of the orientation regions to the OI value of the non-orientation regions is 0.002-0.75.

[0007] According to an embodiment of the present application, the OI value of the orientation regions is 0.1-15, preferably 0.2-5.

[0008] According to an embodiment of the present application, the OI value of the non-oriented area is 5-40, preferably, the OI value of the non-oriented area (22) is 20-40.

[0009] According to an embodiment of the present application, the orientation coefficient λ of the electrode coating satisfies 0<λ<8, preferably, the orientation coefficient λ of the electrode coating satisfies 0.4≤λ≤2.5; the λ=L1 / L2, L1 is the width of the oriented area, and L2 is the width of the non-oriented area.

[0010] According to an embodiment of the present application, the width L1 of the oriented area satisfies 0.05cm<L1<10cm.

[0011] According to an embodiment of the present application, the width L2 of the non-oriented area satisfies 0<L2<80cm, preferably, the width L2 of the non-oriented area satisfies 0.02cm<L2<25cm.

[0012] According to an embodiment of the present application, the first direction is the length direction of the electrode coating.

[0013] According to an embodiment of the present application, the particle size Dv50 of the electrode active material is 7μm-16μm.

[0014] According to an embodiment of the present application, the area density of the electrode coating is 165g·m -2 -280g·m -2 .

[0015] According to an embodiment of the present application, the compacted density of the electrode coating is 1.48g·cm -3 -1.6g·cm -3 .

[0016] According to an embodiment of the present application, the thickness of the electrode coating is 103μm-197μm.

[0017] According to an embodiment of the present application, the electrode sheet is a negative electrode sheet, and the electrode active material comprises graphite.

[0018] According to an embodiment of the present application, the electrode sheet is a positive electrode sheet, and the electrode active material comprises positive electrode ternary material and / or lithium iron phosphate.

[0019] In another aspect of the present application, a method for preparing the electrode sheet is provided, comprising the following steps: coating a slurry containing the electrode active material on the surface of the electrode current collector to form a wet film on the surface of the electrode current collector, thereby obtaining an electrode sheet precursor; and passing the electrode sheet precursor through a magnetic field to form the orientation region and the non-orientation region during the passing of the electrode sheet precursor through the magnetic field, thereby obtaining the electrode sheet; wherein the magnetic field is provided by a magnetic assembly, the magnetic assembly comprises N-pole magnets and S-pole magnets staggered along a fourth direction, and the moving direction of the electrode current collector with the wet film passing through the magnetic field is intersected with the fourth direction or parallel to the fourth direction.

[0020] According to an embodiment of the present application, the maximum magnetic field strength of the magnetic field is 0.5-0.8 T.

[0021] According to an embodiment of the present application, during the passing of the electrode sheet precursor through the magnetic field, the moving speed of the electrode sheet precursor is 1-5 m / min.

[0022] According to an embodiment of the present application, during the passing of the electrode sheet precursor through the magnetic field, the distance between the electrode sheet precursor and the magnetic assembly is 0.5-5 cm.

[0023] According to an embodiment of the present application, during the passing of the electrode sheet precursor through the magnetic field, the relative two sides of the electrode sheet precursor in the thickness direction each exist the magnetic assembly.

[0024] According to an embodiment of the present application, in the magnetic assembly, the distance between the adjacent N-pole magnet and S-pole magnet is 0-5 cm; preferably, the distance between the adjacent N-pole magnet and S-pole magnet is 0-0.5 cm.

[0025] According to an embodiment of the present application, the width of the N-pole magnet in the fourth direction is 1-2 cm.

[0026] According to an embodiment of the present application, the width of the S-pole magnet in the fourth direction is 1-2 cm.

[0027] In another aspect of the present application, a battery comprising the electrode sheet or the electrode sheet prepared according to the method for preparing the electrode sheet is provided.

[0028] In another aspect of the present application, a battery pack comprising the battery is provided.

[0029] In another aspect of the present application, an electric device comprising the battery or the battery pack is provided.

[0030] The electrode coating of the electrode sheet comprises orientation regions and non-orientation regions arranged in an alternating manner in a first direction (the first direction intersects the thickness direction of the electrode coating), the OI value of the orientation regions is less than the OI value of the non-orientation regions, so that the electrode active material in the orientation regions has a good orientation degree, which is conducive to the embedding of active ions such as lithium ions into the electrode active material, thereby promoting the rapid transmission of active ions such as lithium ions in the electrode sheet, reducing the liquid-phase diffusion impedance of the electrode sheet and the internal resistance of the battery, and improving the fast-charging capability and other performances of the battery. At the same time, the non-orientation regions have a relatively high OI value, and the orientation degree of the electrode active material in the non-orientation regions is lower than that in the orientation regions, thereby alleviating the problems of serious expansion and contraction of the electrode sheet during the charging and discharging process of the battery due to the excessively high orientation degree of the electrode active material, and the problems of electrode active material falling off and peeling off of the electrode sheet during the long cycle process of the battery, thereby improving the cycle stability and other performances of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0031] FIG. 1 is a schematic diagram of the arrangement direction of N-pole magnets and S-pole magnets of a magnetic assembly and the moving direction of an electrode sheet precursor according to an embodiment of the present application;

[0032] FIG. 2 is a schematic diagram of the arrangement direction of N-pole magnets and S-pole magnets of a magnetic assembly and the moving direction of an electrode sheet precursor according to another embodiment of the present application;

[0033] FIG. 3 is a schematic diagram of the arrangement direction of N-pole magnets and S-pole magnets of a magnetic assembly and the moving direction of an electrode sheet precursor according to another embodiment of the present application;

[0034] FIG. 4 is a schematic diagram of the relative position relationship between a magnetic assembly and an electrode sheet precursor according to an embodiment of the present application;

[0035] FIG. 5 is a schematic diagram of the structure of an electrode sheet according to an embodiment of the present application;

[0036] FIG. 6 is a surface photograph of an electrode coating according to an embodiment of the present application.

[0037] Reference signs: 1: electrode current collector; 2: electrode coating; 21: orientation region; 22: non-orientation region; 2': wet film; 3: electrode sheet precursor; N: N-pole magnet; S: S-pole magnet; a: first direction; b: second direction; c: third direction; x: fourth direction; y: fifth direction; d: moving direction of the electrode sheet precursor; e: magnetic field direction; H: distance between the electrode sheet precursor and the magnetic assembly; L: spacing between adjacent N-pole magnets and S-pole magnets. DETAILED DESCRIPTION

[0038] In order for those skilled in the art to better understand the scheme of the present application, the present application is further described in detail below. The following specific embodiments are only used to describe the principles and characteristics of the present application, and the examples are used to explain the present application, but not to limit the scope of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0039] The embodiments of the present application provide an electrode sheet, as shown in FIGS. 1-6, which includes an electrode current collector 1, and an electrode coating 2 located on at least one side surface of the electrode current collector 1, the electrode coating 2 including an electrode active material; the electrode coating 2 includes orientation regions 21 and non-orientation regions 22 staggered arranged in a first direction a, the OI value of the orientation regions 21 is less than the OI value of the non-orientation regions 22, and the first direction a intersects the thickness direction (third direction c) of the electrode coating 2.

[0040] According to the research of the inventors, under the above electrode sheet system, the orientation regions 21 have a smaller OI value, in which the electrode active material is more regularly oriented and has a higher degree of orientation, and the orientation of the electrode active material particles in the local area (i.e. the orientation regions 21 in the electrode coating 2) can reduce the tortuosity in the orientation regions 21 and improve the transmission capacity of active ions such as lithium ions; at the same time, the non-orientation regions 22 can alleviate the problems of single reverse expansion and contraction of the electrode active material particles and the shedding of the electrode active material caused thereby, thereby improving the long-term cycle stability and other performances of the battery. Thus, the embodiments of the present application can reduce the battery impedance, improve the fast charging capability (short-term charging capability) of the battery, and at the same time, improve the cycle stability and other performances of the battery.

[0041] In addition, in the embodiments of the present application, the local area of the electrode coating 2 forms the orientation regions 21 and the local area forms the non-orientation regions 22, which not only improves the cycle stability of the electrode sheet and reduces the impedance of the electrode sheet, but also has the advantages of simple preparation of the electrode sheet.

[0042] Further research shows that the ratio of the OI value of the orientation regions 21 to the OI value of the non-orientation regions 22 can be 0.002-0.75, for example, 0.002, 0.005, 0.01, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.75 or a range formed by any two of them, which is conducive to further improving the cycle stability and reducing the impedance of the battery.

[0043] In the above electrode sheet, the electrode active material exists in the form of particles, and the shape can be spherical, spheroidal, or other regular or irregular shapes. The OI value represents the degree of orientation of the crystal structure of the electrode active material particles. The smaller the OI value, the closer the direction in which the crystal structure of the electrode active material particles embeds lithium ions is to being perpendicular, that is, the higher the perpendicularity of the electrode active material particles in the electrode coating 2, the more conducive to reducing tortuosity, and the stronger the ion diffusion capacity.

[0044] In comparison, the smaller the OI value of the orientation region 21, the higher the degree of orientation (perpendicularity) of the electrode active material therein, the more conducive to the transport of active ions such as lithium ions, but if the OI value of the orientation region 21 is too small, it will also increase the degree of expansion of the electrode active material to some extent, affecting the cycle stability and other performances of the battery. Taking these factors into consideration, in some embodiments, the OI value of the orientation region 21 can be 0.1-15, such as 0.1, 0.2, 0.5, 0.8, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 13, 15, or a range formed by any two of them, preferably 0.2-5, which is conducive to further balancing the improvement of the cycle stability and the reduction of the battery impedance of the battery.

[0045] In addition, the OI value of the non-orientation region 22 can be 5-40, and preferably, the OI value can be 20-40, such as 5, 10, 15, 20, 23, 25, 28, 30, 33, 35, 38, 40, or a range formed by any two of them, which is conducive to further balancing the improvement of the cycle stability and the reduction of the battery impedance of the battery.

[0046] In the embodiments of the present application, the number of orientation regions 21 is multiple, and the number of non-orientation regions 22 is multiple. These orientation regions 21 and non-orientation regions 22 are staggered along the first direction a (i.e., the direction from the orientation region 21 to the non-orientation region 22 is parallel to the first direction a), that is, in the first direction a, there is a non-orientation region 22 between every two adjacent orientation regions 21 (i.e., every two adjacent orientation regions 21 are separated by a non-orientation region 22), and there is an orientation region 21 between every two adjacent non-orientation regions 22 (i.e., every two adjacent non-orientation regions 22 are separated by an orientation region 21). Specifically, the orientation regions 21 and non-orientation regions 22 can be staggered throughout the first direction a of the electrode coating 2. The appearance of the electrode coating 2 generally presents alternating light and dark stripes (as shown in FIG. 6, the darker stripes (black areas in FIG. 6) are the orientation regions 21, and the lighter stripes (gray areas in FIG. 6) are the non-orientation regions 22).

[0047] Specifically, as shown in FIG. 4 and FIG. 5, the thickness direction of the electrode coating 2 (also the thickness direction of the electrode sheet) is parallel to the third direction c, and the first direction a intersects with the thickness direction of the electrode coating 2, and the two can be substantially perpendicular. For example, the first direction a can be the width direction of the electrode coating 2 (also the width direction of the electrode sheet), and specifically, the oriented area 21 and the non-oriented area 22 can be staggered arranged in the entire width direction of the electrode coating 2; or the first direction a is the length direction of the electrode coating 2, and specifically, the oriented area 21 and the non-oriented area 22 can be staggered arranged in the entire length direction of the electrode coating 2.

[0048] Compared with the above, when the first direction a is the length direction of the electrode coating 2 (i.e., the oriented area 21 and the non-oriented area 22 are staggered arranged in the length direction of the electrode coating 2), it is beneficial to reduce the battery impedance and improve the cycle stability of the battery and other performances, and at the same time, it is convenient for the preparation of the electrode sheet, and improves the preparation efficiency and yield of the electrode sheet.

[0049] According to the further research of the inventor, the orientation coefficient λ of the electrode coating 2 can satisfy 0 < λ < 8, preferably, the orientation coefficient λ of the electrode coating 2 satisfies 0.4 ≤ λ ≤ 2.5; λ = L1 / L2, L1 is the width of the oriented area 21, and L2 is the width of the non-oriented area 22. By controlling the orientation coefficient λ of the electrode coating 2 within the above range, it is beneficial to further improve the cycle stability of the battery and reduce the battery impedance.

[0050] Exemplarily, λ can be 0.2, 0.4, 0.6, 0.8, 1, 1.3, 1.5, 1.8, 2, 2.3, 2.5, 3, 3.5, 4, 5, 6, 7, 7.5 or a range formed by any two of them.

[0051] In some embodiments, the width L1 of the oriented area 21 satisfies 0.05 cm < L1 < 10 cm, which is beneficial to further improve the cycle stability of the battery and reduce the battery impedance.

[0052] Exemplarily, the width L1 of the oriented area 21 can be 0.07 cm, 0.1 cm, 0.3 cm, 0.5 cm, 0.8 cm, 1 cm, 1.2 cm, 1.5 cm, 2 cm, 3 cm, 4 cm, 5 cm, 6 cm, 7 cm, 8 cm, 9 cm, 10 cm or a range formed by any two of them.

[0053] In some embodiments, the width L2 of the non-oriented region 22 satisfies 0cm < L2 < 80cm, and L2 is, for example, a range consisting of 0.02cm, 0.05cm, 0.1cm, 0.5cm, 1cm, 5cm, 8cm, 10cm, 15cm, 20cm, 25cm, 30cm, 40cm, 50cm, 60cm, 70cm, 80cm or any two of these. Preferably, the width L2 of the non-oriented region 22 satisfies 0.02cm < L2 < 25cm, which is beneficial for further improving the cycle stability of the battery and reducing the battery impedance.

[0054] In this embodiment of the application, the width L1 of the orientation region 21 refers to the width of a single orientation region in the first direction a, and the width L2 of the non-orientation region 22 refers to the width of a single non-orientation region 22 in the first direction a.

[0055] Furthermore, the length of the oriented region 21 in the second direction b and the length of the non-oriented region 22 in the second direction b can be substantially equal to the width of the electrode coating 2 in the second direction b. The second direction b intersects with the first direction a, and the two can be substantially perpendicular. Specifically, the second direction b can be the width direction of the electrode coating 2 (also the width direction of the electrode sheet).

[0056] In addition, the particle size Dv50 of the electrode active material can be 7μm to 16μm, for example, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm or any combination thereof.

[0057] Furthermore, the areal density of electrode coating 2 can be 165 g·m³. -2 ~280g·m -2 (g / m 2 For example, 165g / m 2 170g / m 2 180g / m 2 190g / m 2 200g / m 2 210g / m 2 220g / m 2 230g / m 2 240g / m 2 250g / m 2 260g / m 2 270g / m 2 280g / m 2 or a range consisting of any two of them.

[0058] Furthermore, the compaction density of electrode coating 2 can be 1.48 g·cm³. -3 ~1.6g·cm -3(g / cm 3 ), for example 1.48 g / cm 3 , 1.5 g / cm 3 , 1.53 g / cm 3 , 1.55 g / cm 3 , 1.58 g / cm 3 , 1.6 g / cm 3 , or a range bounded by any of these values.

[0059] In addition, the thickness of the electrode coating 2 can be in the range of 103 μm to 197 μm, for example 103 μm, 109 μm, 115 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, 197 μm, or a range bounded by any of these values.

[0060] In the embodiments of the present application, the thickness of the electrode coating 2 (103-197 μm) refers to the total thickness of the electrode coating 2 provided on the surface of the electrode current collector 1, i.e. the thickness of the electrode coating 2 = the thickness of the electrode sheet - the thickness of the electrode current collector 1. For example, when the electrode current collector 1 has two opposite surfaces each provided with an electrode coating 2, the total thickness of the electrode coating 2 = the thickness of the electrode coating 2 provided on one side surface of the electrode current collector 1 + the thickness of the electrode coating 2 provided on the other side surface of the electrode current collector 1. The thickness of the electrode coating 2 is substantially equal to the ratio of the area density of the electrode coating 2 to the compacted density of the electrode coating 2 (i.e. the thickness of the electrode coating 2 = the area density of the electrode coating 2 / the compacted density of the electrode coating 2).

[0061] In some embodiments, the electrode sheet described above can be a negative electrode sheet, and accordingly the electrode current collector 1 described above is a negative electrode current collector, the electrode coating 2 is a negative electrode coating (a negative electrode active material layer), and the electrode active material is a negative electrode active material, which can include graphite.

[0062] The embodiments of the present application can employ a conventional negative electrode current collector in the art, for example, the negative electrode current collector includes a copper foil.

[0063] In other embodiments, the electrode sheet described above is a positive electrode sheet, and accordingly the electrode current collector 1 described above is a positive electrode current collector, the electrode coating 2 is a positive electrode coating (a positive electrode active material layer), and the electrode active material is a positive electrode active material, which can include a positive electrode ternary material and / or lithium iron phosphate, wherein the positive electrode ternary material includes, for example, a nickel-cobalt-manganese ternary material and / or a nickel-cobalt-aluminum ternary material.

[0064] The embodiments of the present application can employ a conventional positive electrode current collector in the art, for example, the positive electrode current collector includes an aluminum foil.

[0065] In the embodiments of the present application, the electrode coating 2 can be arranged on one side surface of the electrode current collector 1, or the electrode coating 2 can be arranged on both opposite side surfaces of the electrode current collector 1, and when the electrode coating 2 is arranged on both opposite side surfaces of the electrode current collector 1, the electrode coating 2 on one side surface can be the electrode coating 2 including the staggered arrangement of the orientation region 21 and the non-orientation region 22, or the electrode coating 2 on both opposite side surfaces of the electrode current collector 1 can be the electrode coating 2 including the staggered arrangement of the orientation region 21 and the non-orientation region 22.

[0066] Generally, the electrode coating 2 further includes a conductive agent and a binder, and the mass fraction of the electrode active material (i.e., the ratio of the mass of the electrode active material to the total mass of the electrode coating 2) can be 70% to 99%, for example, 70%, 75%, 80%, 85%, 90%, 93%, 95%, 97%, 99%, or a range formed by any two of them, the mass fraction of the conductive agent can be 0.5% to 15%, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 8%, 10%, 13%, 15%, or a range formed by any two of them, and the mass fraction of the binder can be 0.5% to 15%, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 8%, 10%, 13%, 15%, or a range formed by any two of them.

[0067] In the embodiments of the present application, the conductive agent in the electrode coating 2 can be a conventional conductive material in the art, for example, the conductive agent includes one or more of carbon black, carbon nanotubes (CNT), acetylene black, graphene, ketjen black, and carbon fiber.

[0068] In the embodiments of the present application, the binder in the electrode coating 2 can be a conventional binding material in the art, for example, when the electrode sheet is a negative electrode sheet, the binder can include one or more of sodium carboxymethyl cellulose (CMC), styrene butadiene rubber (SBR), polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, an oxirane-containing polymer, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyvinyl alcohol, and sodium polyacrylate; when the electrode sheet is a positive electrode sheet, the binder can include one or more of polyvinylidene fluoride (PVDF), polyvinylidene fluoride, polyvinyl fluoride, polyethylene, polypropylene, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, an oxirane-containing polymer, polyvinylpyrrolidone, polyurethane, and the like.

[0069] The application further provides a preparation method of the electrode sheet, as shown in FIGS. 1-4, which comprises the following steps: coating a slurry containing an electrode active material on the surface of an electrode current collector 1 to form a wet film 2' on the surface of the electrode current collector 1, thereby obtaining an electrode sheet precursor 3; and passing the electrode sheet precursor 3 through a magnetic field to form the oriented region 21 and the non-oriented region 22 in the process of passing the electrode sheet precursor 3 through the magnetic field, thereby obtaining the electrode sheet; wherein the magnetic field is provided by a magnetic assembly, the magnetic assembly comprises N-pole magnets and S-pole magnets staggered along a fourth direction x, and the moving direction d of the electrode sheet precursor 3 (i.e., the electrode current collector 1 with the wet film 2') when passing through the magnetic field intersects (specifically, can be perpendicular to each other, as shown in FIG. 1) or is parallel to the fourth direction x (as shown in FIGS. 2, 3 and 4).

[0070] In the above preparation process, in the process of passing the electrode sheet precursor 3 through the magnetic field, the magnetic assembly applies a magnetic field, the direction e of the magnetic field intersects (for example, can be substantially perpendicular to) the moving direction d of the electrode sheet precursor 3 when passing through the magnetic field, the magnetic assembly is arranged by N-pole magnets and S-pole magnets staggered along the fourth direction x, and the magnetic field generated by the magnetic assembly has different magnetic field strengths in different regions, i.e., magnetic field regions with different magnetic field strengths are formed. When the orientation degree of the electrode active material particles in the wet film 2' is induced by passing through the magnetic field, the magnetic field regions with different magnetic field strengths induce regions with different orientation degrees, so that the electrode coating 2 of the prepared electrode sheet forms the oriented region 21 and the non-oriented region 22 staggered along the first direction a.

[0071] Generally, the maximum magnetic field strength of the above magnetic field (i.e., the magnetic field strength of the magnetic field region with the maximum magnetic field strength) can be 0.5-0.8 T, for example, 0.5 T, 0.6 T, 0.7 T, 0.8 T or a range formed by any two of them.

[0072] Specifically, in the process of passing the electrode sheet precursor 3 through the magnetic field, the moving speed (walking speed) of the electrode sheet precursor 3 can be 1-5 m / min, for example, 1 m / min, 2 m / min, 3 m / min, 4 m / min, 5 m / min or a range formed by any two of them.

[0073] Specifically, as shown in FIG. 4, in the process of passing the electrode sheet precursor 3 through the magnetic field, there are magnetic assemblies on the opposite sides of the thickness direction (the third direction c in FIG. 4) of the electrode sheet precursor 3, respectively, i.e., the magnetic field regions with magnetic fields are formed between the magnetic assemblies on the opposite sides of the thickness direction of the electrode sheet precursor 3, and the electrode sheet precursor 3 passes through the magnetic field region to realize the passing of the electrode sheet precursor 3 through the magnetic field.

[0074] The thickness direction of the pole piece precursor 3 intersects the moving direction d of the pole piece precursor 3, and the thickness direction of the pole piece precursor 3 can be substantially perpendicular to the moving direction d of the pole piece precursor 3. The moving direction of the pole piece precursor 3 can be substantially parallel to the length direction of the pole piece precursor 3 (also the length direction of the prepared electrode piece).

[0075] Specifically, as shown in FIG. 4, the distance H between the pole piece precursor 3 and the magnetic assembly (i.e., the vertical height of the pole piece precursor relative to the magnetic assembly) during the process of passing the pole piece precursor 3 through the magnetic field can be 0.2 cm to 6 cm, and preferably, H is 0.5 cm to 5 cm, for example, 0.2 cm, 0.5 cm, 1 cm, 2 cm, 3 cm, 4 cm, 5 cm, 6 cm, or a range formed by any two of them.

[0076] In the embodiments of the present application, as shown in FIG. 4, the distance H between the pole piece precursor 3 and the magnetic assembly refers to the distance from the pole piece precursor 3 to the magnetic assembly on either side of the pole piece precursor 3 in the third direction c.

[0077] Generally, as shown in FIGS. 1 to 4, any magnetic assembly includes a plurality of N-pole magnets and a plurality of S-pole magnets, and the N-pole magnets and the S-pole magnets are staggered in the fourth direction x. There is an S-pole magnet between every two adjacent N-pole magnets, and there is an N-pole magnet between every two adjacent S-pole magnets.

[0078] In addition, as shown in FIGS. 1 to 4, the distance L between the adjacent N-pole magnets and S-pole magnets in the magnetic assembly can be substantially 0 (the N-pole magnets and the S-pole magnets are closely arranged, as shown in FIGS. 3 and 4), or the distance L between the adjacent N-pole magnets and S-pole magnets is greater than 0 (i.e., there is a gap between the adjacent N-pole magnets and S-pole magnets, as shown in FIGS. 1 and 2).

[0079] In some embodiments, the distance L between the adjacent N-pole magnets and S-pole magnets can be 0 to 5 cm; preferably, L can be 0 to 0.5 cm, for example, 0, 0.1 cm, 0.2 cm, 0.3 cm, 0.4 cm, 0.5 cm, 1 cm, 1.5 cm, 2 cm, 2.5 cm, 3 cm, 3.5 cm, 4 cm, 4.5 cm, 5 cm, or a range formed by any two of them.

[0080] In the embodiments of the present application, the distance L between the adjacent N-pole magnets and S-pole magnets refers to the distance in the fourth direction x between any N-pole magnet and the adjacent S-pole magnet (also the distance in the fourth direction x between any S-pole magnet and the adjacent N-pole magnet).

[0081] Specifically, as shown in FIGS. 1-3, for each N-pole magnet, the N-pole magnet can include a plurality of N-pole magnetic pieces arranged along a fifth direction y, which are generally closely arranged (i.e., the interval of two adjacent N-pole magnetic pieces in the fifth direction y is 0), thereby forming the N-pole magnet.

[0082] Specifically, as shown in FIGS. 1-3, for each S-pole magnet, the S-pole magnet can include a plurality of S-pole magnetic pieces arranged along a fifth direction y, which are generally closely arranged (i.e., the interval of two adjacent S-pole magnetic pieces in the fifth direction y is 0), thereby forming the S-pole magnet.

[0083] Specifically, the fifth direction y intersects the fourth direction x, and the two directions can be substantially perpendicular; the fifth direction y intersects the third direction c, and the two directions can be substantially perpendicular; and the fourth direction x intersects the third direction c, and the two directions can be substantially perpendicular.

[0084] In addition, the width of the N-pole magnet in the fourth direction x can be 1-2 cm, and the width of the S-pole magnet in the fourth direction can be 1-2 cm. The width of the N-pole magnet in the fourth direction x can be the same as the width of the S-pole magnet in the fourth direction x (as shown in FIGS. 1-4).

[0085] In the embodiments of the present application, the width of the N-pole magnet in the fourth direction x refers to the width of one N-pole magnet in the fourth direction x, which is equal to the width of any N-pole magnetic piece forming the N-pole magnet in the fourth direction x; and the width of the S-pole magnet in the fourth direction x refers to the width of one S-pole magnet in the fourth direction x, which is equal to the width of any S-pole magnetic piece forming the S-pole magnet in the fourth direction x.

[0086] In some embodiments, for any N-pole magnetic piece forming the N-pole magnet, the length L of the cross section parallel to the fifth direction y can be 1-2 cm, and the width W of the cross section parallel to the fourth direction x can be 1-2 cm (i.e., the size of the N-pole magnetic piece is L N *W N ). N N .

[0087] In some embodiments, for any S-pole magnetic piece forming the S-pole magnet, the length L of the cross section parallel to the fifth direction y can be 1-2 cm, and the width W of the cross section parallel to the fourth direction x can be 1-2 cm (i.e., the size of the S-pole magnetic piece is L s *W s ). s s .

[0088] Specifically, the width of the N-pole magnetic piece and the width of the S-pole magnetic piece can be substantially equal.

[0089] ​​Specifically, the drying can be performed simultaneously with the passing of the pole piece precursor 3 through the magnetic field, i.e., the magnetic assembly can be arranged in an oven for drying the wet film 2', so as to provide a magnetic field in the oven, and the pole piece precursor 3 enters the oven to perform the drying while passing through the magnetic field. Alternatively, the drying can be performed after the pole piece precursor 3 passes through the magnetic field, for example, by entering an oven to perform the drying. After the drying, the cold-pressing is performed to form the electrode coating 2 having the alternating arrangement of the oriented regions 21 and the non-oriented regions 22 on the surface of the electrode current collector 1, and then the electrode sheet is prepared through the slitting, cutting and other processes.

[0090] In the embodiment, the slurry containing the electrode active material can be prepared by a conventional method in the art. For example, when the electrode sheet is a negative electrode sheet, the negative electrode active material, the conductive agent, the binder and other components used for forming the negative electrode coating can be dispersed in a first solvent, such as deionized water and / or N-methyl pyrrolidone (NMP), to prepare a negative electrode slurry (i.e., the slurry containing the electrode active material), which is then coated on the surface of the negative electrode current collector. After the magnetic field induction, the drying, the cold-pressing, the slitting, the cutting and other processes, the negative electrode sheet is prepared. When the electrode sheet is a positive electrode sheet, the positive electrode active material, the conductive agent, the binder and other components used for forming the positive electrode coating can be dispersed in a second solvent, such as N-methyl pyrrolidone (NMP), to prepare a positive electrode slurry (i.e., the slurry containing the electrode active material), which is then coated on the surface of the positive electrode current collector. After the magnetic field induction, the drying, the cold-pressing, the slitting, the cutting and other processes, the positive electrode sheet is prepared.

[0091] In the embodiment, the slurry containing the electrode active material can be prepared by a conventional method in the art. For example, when the electrode sheet is a negative electrode sheet, the negative electrode active material, the conductive agent, the binder and other components used for forming the negative electrode coating can be dispersed in a first solvent, such as deionized water and / or N-methyl pyrrolidone (NMP), to prepare a negative electrode slurry (i.e., the slurry containing the electrode active material), which is then coated on the surface of the negative electrode current collector. After the magnetic field induction, the drying, the cold-pressing, the slitting, the cutting and other processes, the negative electrode sheet is prepared. When the electrode sheet is a positive electrode sheet, the positive electrode active material, the conductive agent, the binder and other components used for forming the positive electrode coating can be dispersed in a second solvent, such as N-methyl pyrrolidone (NMP), to prepare a positive electrode slurry (i.e., the slurry containing the electrode active material), which is then coated on the surface of the positive electrode current collector. After the magnetic field induction, the drying, the cold-pressing, the slitting, the cutting and other processes, the positive electrode sheet is prepared.

[0092] In the embodiment, the slurry containing the electrode active material can be prepared by a conventional method in the art. For example, when the electrode sheet is a negative electrode sheet, the negative electrode active material, the conductive agent, the binder and other components used for forming the negative electrode coating can be dispersed in a first solvent, such as deionized water and / or N-methyl pyrrolidone (NMP), to prepare a negative electrode slurry (i.e., the slurry containing the electrode active material), which is then coated on the surface of the negative electrode current collector. After the magnetic field induction, the drying, the cold-pressing, the slitting, the cutting and other processes, the negative electrode sheet is prepared. When the electrode sheet is a positive electrode sheet, the positive electrode active material, the conductive agent, the binder and other components used for forming the positive electrode coating can be dispersed in a second solvent, such as N-methyl pyrrolidone (NMP), to prepare a positive electrode slurry (i.e., the slurry containing the electrode active material), which is then coated on the surface of the positive electrode current collector. After the magnetic field induction, the drying, the cold-pressing, the slitting, the cutting and other processes, the positive electrode sheet is prepared.

[0093] The processes such as the coating, the drying, the cold-pressing, the slitting and the cutting are conventional processes for preparing the electrode sheet by the coating method in the art, and are not particularly limited.

[0093] The embodiment also provides a battery comprising the electrode sheet or the electrode sheet prepared according to the preparation method of the electrode sheet, which has the advantages corresponding to the electrode sheet, and will not be described herein.

[0094] The battery of the embodiment can be a lithium ion battery (e.g., a lithium ion power battery), a solar cell or other novel energy storage battery.

[0095] Generally, the battery includes an electrolyte, a cell, and a packaging body for packaging the cell, the electrolyte is injected into the cell in the packaging body, and the cell includes a positive electrode sheet, a negative electrode sheet, and a separator between the positive electrode sheet and the negative electrode sheet. The cell can be a laminated cell, i.e., the cell is formed by interleaving and stacking the positive electrode sheet, the separator, and the negative electrode sheet; or the cell is a wound cell, i.e., the positive electrode sheet, the separator, and the negative electrode sheet are sequentially stacked and then wound to form a cell having a wound structure.

[0096] In the embodiments of the present application, the positive electrode sheet can be the electrode sheet having the interleaved orientation region 21 and the non-orientation region 22 (i.e., the positive electrode coating includes the interleaved orientation region 21 and the non-orientation region 22), the negative electrode sheet can be the electrode sheet having the interleaved orientation region 21 and the non-orientation region 22 (i.e., the negative electrode coating includes the interleaved orientation region 21 and the non-orientation region 22), or both the positive electrode sheet and the negative electrode sheet are the electrode sheets having the interleaved orientation region 21 and the non-orientation region 22.

[0097] The electrolyte of the embodiments of the present application can be a conventional electrolyte in the art, for example, the electrolyte is a non-aqueous electrolyte, which can specifically include an organic solvent, an additive, and an electrolyte salt. The organic solvent can include one or more of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), and diethyl carbonate, for example. The additive can include vinylene carbonate (VC) and / or fluoroethylene carbonate (FEC), for example. The electrolyte salt can include a lithium salt, which can include lithium hexafluorophosphate (LiPF6) and / or lithium bis(fluorosulfonyl)imide (LiFSI), for example, but is not limited thereto.

[0098] In the embodiments of the present application, the separator is used to separate the positive electrode sheet and the negative electrode sheet to avoid short circuit caused by contact between the positive electrode sheet and the negative electrode sheet. The separator used in the embodiments of the present application can be a conventional separator in the art, and no particular limitation is made thereto.

[0099] In the embodiments of the present application, the cell can be packaged by using a conventional packaging body (shell) material in the art, and the battery can be a conventional battery type and structure in the art. For example, the battery can be a soft-pack lithium ion battery, and the packaging body can include an aluminum plastic film.

[0100] The cell can be assembled into a battery by using a conventional method in the art. For example, the positive electrode sheet, the separator, and the negative electrode sheet can be made into a cell (e.g., a wound cell), placed in a shell, dried, injected with an electrolyte, and then subjected to vacuum packaging, standing, formation, shaping, and other processes to obtain a lithium ion battery. These processes are conventional operations in the art, and no particular limitation is made thereto.

[0101] The application further provides a battery pack comprising the battery, which has the advantages corresponding to the electrode sheet and will not be repeated here.

[0102] Generally, the battery pack comprises a plurality of the batteries, which are connected to form the battery pack as single batteries. The batteries can be electrically connected by conventional methods in the art, such as series connection, parallel connection, or mixed connection comprising both series connection and parallel connection, and the like, without particular limitation.

[0103] The application further provides a power consuming device comprising the battery or the battery pack, which has the advantages corresponding to the electrode sheet and will not be repeated here.

[0104] The power consuming device of the application can be a conventional power consuming device in the art, such as a power device (e.g., an electric vehicle, an electric automobile), an electronic device (e.g., a mobile phone, a tablet computer, a notebook computer, a digital camera, etc.), a wearable device (e.g., a watch, a bracelet, a VR glasses, etc.), without particular limitation.

[0105] In the application, the XRD analysis can be performed on each region of the electrode coating 2 to measure the OI value of the electrode active material in each region. Specifically, the OI value represents the orientation degree of the crystal structure of the electrode active material particles. In the XRD analysis result of a certain region of the electrode coating 2, I1 is the XRD peak area integral value of the direction in which the active ion (e.g., lithium ion) is embedded into the crystal structure of the electrode active material particles, and I2 is the XRD peak area integral value of the direction in which the active ion is less likely to be embedded (i.e., the direction in which the active ion is less likely to be embedded is perpendicular to the direction in which the active ion is embedded into the crystal structure of the electrode active material particles), and then the orientation value of the crystal structure inside the electrode active material particles (i.e., the OI value of the electrode active material) = I2 / I1, OI value > 0. Taking the negative electrode sheet using graphite as the negative electrode active material as an example, the XRD analysis is performed on each region of the negative electrode coating, and in the XRD analysis result, I1 is the 110 crystal direction peak area of the graphite, I2 is the 004 crystal direction peak area of the graphite, and the OI value of the graphite = I2 / I1. Through the OI value of the graphite, the arrangement order degree (the smaller the OI value, the higher the order degree (perpendicularity)) of the crystal structure of the graphite particles can be represented.

[0106] In the application, the process of testing the area density of the electrode coating 2 can comprise: taking an electrode sheet sample, testing the total mass m1 of the electrode sheet sample and the surface area S of one side in the thickness direction of the electrode sheet sample; then scraping off the electrode coating 2 on the electrode sheet sample, testing the mass m2 of the obtained electrode current collector 1, and then the area density of the electrode coating 2 = (m1-m2) / S.

[0107] In the embodiments of the present application, the compaction density of the electrode coating 2 = the areal density of the electrode coating 2 / the total thickness of the electrode coating 2, wherein the testing process of the areal density of the electrode coating 2 is as described above, and the testing process of the total thickness of the electrode coating 2 can include: taking an electrode sheet sample, testing the total thickness T1 of the electrode sheet sample (T1 = the total thickness of the electrode coating 2 + the thickness of the electrode current collector 1, when the positive and negative surfaces of the electrode current collector 1 are each provided with the electrode coating 2, the total thickness of the electrode coating 2 = the thickness of the electrode coating 2 on one side surface of the electrode current collector 1 + the thickness of the electrode coating 2 on the other side surface of the electrode current collector 1); then scraping off the electrode coating 2 on the electrode sheet sample, testing the thickness T2 of the obtained electrode current collector 1, and then the total thickness of the electrode coating 2 = T1-T2.

[0108] In specific implementation, the micrometer can be used to measure the average thickness T1 of the electrode sheet and the average thickness T2 of the electrode current collector 1.

[0109] In the embodiments of the present application, the particle size Dv50 of the electrode active material represents the particle size at which the electrode active material particles reach 50% of the volume accumulation from the small particle size side in the volume-based particle size distribution, and the particle size Dv50 of the electrode active material can be measured by a laser particle size analyzer. Specifically, after obtaining the electrode sheet, the electrode coating 2 can be scraped off from the electrode current collector, and the obtained electrode coating material can be uniformly dispersed in water, then filtered, and the obtained solid particle product is dried, and then the particle size Dv50 of the solid particle product is tested by a laser particle size analyzer, and the test result is the particle size Dv50 of the electrode active material.

[0110] In specific implementation, the battery can be disassembled to obtain the electrode sheet, and then the OI value of different regions of the electrode coating 2 of the electrode sheet, the areal density and compaction density of the electrode coating 2, and the particle size Dv50 of the electrode active material, etc. can be tested.

[0111] The present application is further described below through specific embodiments. In the following embodiments, the testing process of the areal density and compaction density of the electrode coating 2, the XRD test of graphite (graphite OI value = I2 / I1, I1 is the peak area of the 110 crystal direction of graphite, and I2 is the peak area of the 004 crystal direction of graphite), and other parameters are as described above, and will not be described again below.

[0112] In the following examples and comparative examples, unless otherwise specified, the electrolyte is prepared according to the following process:

[0113] In an argon atmosphere glove box with water content <1 ppm and oxygen content <1 ppm, DMC, EMC, EC, VC, FEC, LiPF6 and LiFSI were mixed to prepare an electrolyte; wherein the mass ratio of DMC, EMC and EC was 50:20:30, the mass percentage of VC in the electrolyte was 3.0%, the mass percentage of FEC in the electrolyte was 0.1%, the mass percentage of LiPF6 in the electrolyte was 7.9%, and the mass percentage of LiFSI in the electrolyte was 5%.

[0114] Example 1

[0115] 1. Preparation of the positive electrode sheet

[0116] Lithium iron phosphate (LiFePO4), carbon nanotubes (CNT) and polyvinylidene fluoride were mixed in a mass ratio of 97.3:0.8:1.9, N-methyl pyrrolidone (NMP) was added, and the system was stirred to form a uniform positive electrode slurry under the action of a vacuum stirrer. Then the positive electrode slurry was uniformly coated on the positive and negative surfaces of the positive electrode current collector aluminum foil. After drying at 100°C, cold pressing, slitting and sheet cutting were performed, and the positive electrode sheet was obtained after drying at 100°C for 4h under vacuum conditions.

[0117] 2. Preparation of the negative electrode sheet

[0118] (1) Graphite, carbon black, styrene butadiene rubber (SBR) and sodium carboxymethyl cellulose (CMC) were fully stirred and mixed in deionized water in a mass ratio of 95:1:3:1 to form a uniform negative electrode slurry. The negative electrode slurry was coated on the positive and negative surfaces of the negative electrode current collector copper foil to form wet films 2' on the positive and negative surfaces of the copper foil, respectively, to obtain an electrode sheet precursor 3.

[0119] (2) The magnetic assembly was placed in an oven to provide a magnetic field in the oven, and the electrode sheet precursor 3 entered the oven at a speed of 3m / min, passing through the magnetic field in the process of passing through the oven, and drying was performed at the same time.

[0120] Wherein, the moving direction d of the electrode sheet precursor 3 is perpendicular to the fourth direction x.

[0121] Wherein, the relative two sides in the thickness direction (third direction c) of the electrode sheet precursor 3 each have a magnetic assembly, and each side of the magnetic assembly is formed by a plurality of N-pole magnets and a plurality of S-pole magnets being arranged in the fourth direction x in an interlaced and close manner (the distance L between adjacent N-pole magnets and S-pole magnets is 0).

[0122] Wherein, each N-pole magnet is formed by a plurality of N-pole magnetic blocks being arranged in the fifth direction y in a close manner, and the size of each N-pole magnetic block is 1cm*1cm (i.e. the length L of the cross section of the N-pole magnetic block parallel to the fifth direction y is 1cm, and the width W is 1cm). N =1cm, width WN = 1 cm).

[0123] Each S-pole magnet is composed of a plurality of S-pole magnetic blocks closely arranged in the fifth direction y, and each S-pole magnetic block has a size of 1 cm * 1 cm (i.e. the length L of the cross section of the S-pole magnetic block parallel to the fifth direction y is 1 cm, and the width W of the cross section of the S-pole magnetic block parallel to the first direction a is 1 cm). s = 1 cm, and the width W of the cross section of the S-pole magnetic block parallel to the first direction a is 1 cm). s = 1 cm, and the width W of the cross section of the S-pole magnetic block parallel to the first direction a is 1 cm).

[0124] The distance (i.e. the vertical height of the pole piece precursor 3 relative to the magnetic assembly) H between the pole piece precursor 3 and the magnetic assembly is 0.5 mm.

[0125] (3) The pole piece precursor 3 after the oven is dried, cold-pressed, so that the wet film 2' located on the front and back two surfaces of the copper foil forms a negative electrode coating, and then after slitting and cutting, a negative electrode piece is obtained;

[0126] The areal density of the negative electrode coating is 230 g / m 2 , and the compacted density is 1.55 g / cm 3 .

[0127] The negative electrode coating of the negative electrode piece is staggered with the orientation region 21 and the non-orientation region 22 along the first direction a (see the surface photo of the negative electrode coating in FIG. 6).

[0128] 3. Preparation of a lithium ion battery

[0129] The positive electrode piece, the separator, and the negative electrode piece are sequentially stacked with the separator between the positive electrode piece and the negative electrode piece to play a role of isolation, and then are wound and placed in an outer packaging foil (aluminum plastic film). After drying, the electrolyte prepared above is injected into the outer packaging foil, and then the lithium ion battery is prepared through processes such as vacuum packaging, standing, formation, and shaping.

[0130] Examples 2-21: The difference from Example 1 is that the related parameters of the negative electrode piece (the particle size Dv50 of the graphite, the OI value of the orientation region 21 (OI1 in Table 1), the OI value of the non-orientation region 22 (OI2 in Table 1), the ratio of the OI value of the orientation region 21 to the OI value of the non-orientation region 22 (OI1 / OI2 in Table 1), the orientation coefficient λ, the width L1 of the orientation region 21), and the related parameters in the preparation process of the negative electrode piece (the vertical height H of the pole piece precursor 3 relative to the magnetic assembly, the walking speed of the pole piece precursor 3, the moving direction d of the pole piece precursor 3, the distance L between the adjacent N-pole magnet and S-pole magnet, the size of the S-pole magnetic block and the N-pole magnetic block) are different, and the specific conditions are shown in Table 1 (related parameters in the preparation process of the negative electrode piece) and Table 2 (related parameters of the negative electrode piece). In addition to the differences shown in Table 1 and Table 2, the remaining conditions are the same.

[0131] Examples 22 to 24: The difference from Example 1 is that the relevant parameters of the negative electrode (particle size Dv50 of graphite, OI value of orientation region 21 (OI1 in Table 1), OI value of non-oriented region 22 (OI2 in Table 1), and the ratio of OI value of orientation region 21 to OI value of non-oriented region 22 (OI1 / OI2 in Table 1) are changed. In the preparation of the negative electrode, step (1) is to mix graphite, carbon black, styrene-butadiene rubber (SBR), and sodium carboxymethyl cellulose (CMC) in deionized water at a mass ratio of 96:1:1:2.

[0132] Comparative Example 1: The difference from Example 1 is that magnetic field induction is not performed (i.e., no magnetic components are placed in the oven and no magnetic field is applied during the process of the electrode precursor 3 passing through the oven), and the other conditions are the same as in Example 1.

[0133] Comparative Example 2: Before drying the electrode precursor 3, a voltage (20V) and a magnetic field (magnetic field strength of 0.8T) were applied to the electrode precursor 3 (a negative electrode current collector copper foil with a wet film 2' formed on its surface) to induce magnetoelectric crystal structure orientation and maintain a uniform and stable magnetic field. Then, normal drying was started (no magnetic field was applied during the drying process) so that the graphite particles in all areas of the formed negative electrode coating were oriented (graphite OI values ​​are shown in Table 2); the other conditions were the same as in Example 1.

[0134] Following the procedure below, the 50% SOC DCIR, cycle capacity retention, and liquid phase diffusion resistance (Ω) of the negative electrode of each example and comparative example lithium-ion battery were tested respectively. The performance test results of the lithium-ion battery are shown in Table 3.

[0135] (1) 50% SOC DC internal resistance test: At room temperature (25±5℃), the battery is discharged to 2.0V with a constant current of 1 / 3C, charged to 50% SOC with a constant current of 1 / 3C, and left to stand for 30min; discharged with a constant current of 1.5C for 30s, and the DC internal resistance at 50% SOC is measured.

[0136] (2) Long-term cycle test: Charge the lithium-ion battery to 3.8V at a constant current of 0.5C and let it rest for 10 minutes; then discharge it to 2.0V at a constant current of 0.5C and let it rest for 10 minutes. Repeat this cycle 500 times and record the discharge capacity C1. The ratio of the discharge capacity C1 to the initial capacity C0 is the capacity retention rate after long-term cycle (i.e., capacity retention rate = C1 / C0).

[0137] (3) Liquid-phase diffusion impedance test: two above-mentioned negative electrode sheets and a separator were assembled into a pole core in sequence (the separator was located between the two negative electrode sheets); the pole core was placed in an outer packaging shell (aluminum plastic film), baked, and injected with electrolyte, and then subjected to packaging, infiltration and other processes to obtain a liquid-phase diffusion impedance battery. The CHI Chenhua electrochemical workstation was used to test the liquid-phase diffusion impedance of the liquid-phase diffusion impedance battery in a frequency range of 300000 Hz-0.05 Hz.

[0138] Table 1: Related parameters in the process of preparing the electrode sheet Note: In Table 1, the size of the magnetic block refers to the size of the N-pole magnetic block and the size of the S-pole magnetic block, for example, in Example 1, the size of the magnetic block is 1 cm*1 cm, which means that the size of the N-pole magnetic block and the size of the S-pole magnetic block are both 1 cm*1 cm.

[0139] Table 2: Related parameters of the negative electrode sheet

[0140] Table 3: Performance test results of the lithium ion battery

[0141] It can be seen that in the negative electrode sheet of Comparative Example 1, the OI value of the negative electrode coating is 39, the liquid-phase diffusion impedance of the negative electrode sheet is large (>0.6 Ω), and the battery internal resistance is large (the 50% SOC DCIR of the battery is 1.436 Ω); in the negative electrode sheet of Comparative Example 2, the OI value of the negative electrode coating is 0.1, which can reduce the liquid-phase diffusion impedance and the battery internal resistance of the negative electrode sheet to a certain extent, but the cycle stability of the battery is seriously deteriorated (the capacity retention rate is low, with a value of 79.1%). Compared with Comparative Examples 1 and 2, in the negative electrode sheets of Examples 1-21, the negative electrode coating comprises staggered orientation regions and non-orientation regions, the OI value of the orientation region is less than that of the non-orientation region, which can make the negative electrode sheet and the battery have low impedance and high cycle stability (the liquid-phase diffusion impedance of the negative electrode sheet is not higher than 0.597 Ω, the 50% SOC DCIR of the battery is not higher than 1.3 Ω, and the cycle capacity retention rate of the battery is not less than 82%), and the battery has good fast charging performance and cycle life and other performances.

[0142] Further, compared with Example 14, Examples 1-3, 8, 11-14 are beneficial to further reduce the liquid-phase diffusion impedance of the negative electrode sheet and the battery internal resistance, while maintaining a higher capacity retention rate of the battery, by controlling the OI value of the oriented area to be in the range of 0.1-15, and the ratio of the OI value of the oriented area to the OI value of the non-oriented area to be in the range of 0.002-0.75. Especially, Examples 1-3 and 11 are beneficial to more significantly reduce the liquid-phase diffusion impedance of the negative electrode sheet (not higher than 0.493 Ω) and the battery internal resistance (50% SOC DCIR of the battery is not higher than 0.787 Ω), and maintain a higher capacity retention rate of the battery (not lower than 91.5%), by further controlling the OI value of the oriented area to be in the range of 0.2-5.

[0143] Further, compared with Example 10, Examples 3-6, 9, 15-17 are beneficial to further reduce the liquid-phase diffusion impedance of the negative electrode sheet and the battery internal resistance, and improve the capacity retention rate of the battery, by controlling the orientation coefficient λ of the negative electrode coating to be in the range of 0<λ<8. Especially, Examples 3-5, 9, 15-17 are beneficial to more significantly reduce the liquid-phase diffusion impedance of the negative electrode sheet (not higher than 0.411 Ω) and the battery internal resistance (50% SOC DCIR of the battery is not higher than 0.689 Ω), and maintain a higher capacity retention rate of the battery (not lower than 88.9%), by further controlling the orientation coefficient λ of the negative electrode coating to be in the range of 0.4≤λ≤2.5.

[0144] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing examples, or make equivalent substitutions for part or all of the technical features; and these modifications or substitutions do not make the essence of the corresponding technical solution deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An electrode tab, wherein, The electrode sheet comprises an electrode current collector (1) and an electrode coating (2) on at least one side surface of the electrode current collector (1), wherein the electrode coating (2) comprises an electrode active material; The electrode coating (2) comprises orientation regions (21) and non-orientation regions (22) arranged alternately in a first direction (a), wherein the OI value of the orientation regions (21) is less than the OI value of the non-orientation regions (22), and the first direction (a) intersects the thickness direction of the electrode coating (2).

2. The electrode pad of claim 1, wherein, The ratio of the OI value of the orientation regions (21) to the OI value of the non-orientation regions (22) is 0.002-0.

75.

3. The electrode sheet according to claim 1 or 2, wherein The OI value of the orientation regions (21) is 0.1-15, preferably 0.2-5.

4. The electrode sheet according to any one of claims 1 to 3, wherein, The OI value of the non-orientation regions (22) is 5-40, preferably the OI value of the non-orientation regions (22) is 20-40.

5. The electrode pad of claim 1, wherein, The orientation coefficient λ of the electrode coating (2) satisfies 0<λ<8, preferably the orientation coefficient λ of the electrode coating (2) satisfies 0.4≤λ≤2.

5. The λ=L1 / L2, L1 is the width of the orientation regions (21), and L2 is the width of the non-orientation regions (22).

6. The electrode sheet according to any one of claims 1 to 5, wherein The width L1 of the orientation regions (21) satisfies 0.05 cm 7. The electrode sheet according to any one of claims 1 to 6, wherein The width L2 of the non-orientation regions (22) satisfies 0 8. The electrode sheet according to any one of claims 1 to 7, wherein The first direction (a) is the length direction of the electrode coating (2).

9. The electrode sheet according to any one of claims 1 to 5, wherein The particle size Dv50 of the electrode active material is 7-16 μm.

10. The electrode sheet according to any one of claims 1 to 9, wherein The areal density of the electrode coating (2) is 165 g m -2 ~ 280 g m -2 .

11. The electrode sheet according to any one of claims 1 to 10, wherein The compacted density of the electrode coating (2) is 1.48 g-cm -3 ~ 1.6 g-cm -3 .

12. The electrode sheet according to any one of claims 1 to 11, wherein The thickness of the electrode coating (2) is 103-197 μm.

13. The electrode sheet according to any one of claims 1 to 12, wherein The electrode sheet is a negative electrode sheet, and the electrode active material comprises graphite.

14. The electrode sheet according to any one of claims 1 to 13, wherein The electrode sheet is a positive electrode sheet, and the electrode active material comprises positive electrode ternary material and / or lithium iron phosphate.

15. A method of making the electrode sheet of any one of claims 1-14, wherein, The method comprises the following steps: A slurry containing the electrode active material is coated on the surface of the electrode current collector (1) to form a wet film (2') on the surface of the electrode current collector (1), thereby obtaining an electrode sheet precursor (3); The electrode sheet precursor (3) passes through a magnetic field to form the orientation regions (21) and the non-orientation regions (22) during the process, thereby obtaining the electrode sheet, wherein the magnetic field is provided by a magnetic assembly comprising N-pole magnets and S-pole magnets arranged alternately along a fourth direction (x), and the moving direction of the electrode current collector (1) with the wet film (2') passing through the magnetic field intersects the fourth direction (x) or is parallel to the fourth direction (x).

16. The method of producing an electrode sheet according to claim 15, wherein The maximum magnetic field strength of the magnetic field is 0.5-0.8 T.

17. The method of producing an electrode sheet according to claim 15, wherein During the process of passing the electrode sheet precursor (3) through the magnetic field, the moving speed of the electrode sheet precursor (3) is 1-5 m / min.

18. The method of making an electrode patch according to any one of claims 15-17, wherein, During the process of passing the electrode sheet precursor (3) through the magnetic field, the distance between the electrode sheet precursor (3) and the magnetic assembly is 0.5-5 cm.

19. The method of making an electrode sheet according to any one of claims 15-18, wherein, In the process of passing the pole piece precursor (3) through the magnetic field, the pole piece precursor (3) has the magnetic assembly on both sides in the thickness direction.

20. The method of making an electrode patch according to any one of claims 15-19, wherein, In the magnetic assembly, the distance between the adjacent N-pole magnet and S-pole magnet is 0-5 cm; preferably, the distance between the adjacent N-pole magnet and S-pole magnet is 0-0.5 cm.

21. The method of making an electrode patch according to any one of claims 15-20, wherein, The width of the N-pole magnet in the fourth direction (x) is 1-2 cm.

22. The method of making an electrode patch according to any one of claims 15-21, wherein, The width of the S-pole magnet in the fourth direction (x) is 1-2 cm.

23. A battery, wherein, An electrode sheet comprising the electrode sheet of any one of claims 1-14 or prepared by the method of any one of claims 15-22.

24. A battery pack, wherein, A battery comprising the battery of claim 23.

25. An electrical device, comprising: A battery pack comprising the battery of claim 23 or the battery pack of claim 24.

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