An electrode sheet, a method of manufacturing the same, a battery, a battery pack, and an electric device

Abstract

This invention provides an electrode sheet and its preparation method, a battery, a battery pack, and an electrical device. The electrode sheet includes an electrode current collector and an electrode coating located on at least one side surface of the electrode current collector. The electrode coating includes an electrode active material. The electrode coating includes oriented 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 with the thickness direction of the electrode coating. This invention can simultaneously reduce battery impedance and improve battery cycle stability.

Description

Technical Field

[0001] This invention relates to the field of batteries, specifically to an electrode sheet and its preparation method, a battery, a battery pack, and an electrical device. Background Technology

[0002] Electrode sheets are crucial components of batteries. The diffusion capacity of active ions such as lithium ions within the electrode sheets determines the charging rate of the battery (e.g., a power battery). By controlling the orientation of the active electrode materials within the electrode sheets, arranging them in a manner conducive to the insertion of active ions like lithium ions into the active electrode materials, the rapid transport of active ions within the electrode sheets can be promoted, reducing electrode sheet impedance and improving battery fast-charging capabilities. However, the oriented arrangement of the active electrode materials in the electrode sheets can exacerbate their expansion during battery charging and discharging, leading to phenomena such as detachment and peeling during long-term battery cycling, thus affecting the battery's cycle stability and other performance characteristics. Therefore, how to balance reducing battery impedance and improving battery cycle stability is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0003] This invention provides an electrode sheet and its preparation method, a battery, a battery pack, and an electrical device, which can simultaneously reduce battery impedance and improve battery cycle stability, effectively overcoming the defects of the prior art.

[0004] In one aspect, the present invention provides an electrode sheet comprising an electrode current collector and an electrode coating located on at least one side surface of the electrode current collector, the electrode coating comprising an electrode active material; the electrode coating comprising oriented regions and non-oriented regions arranged alternately in a first direction, the OI value of the oriented regions being less than the OI value of the non-oriented regions, the first direction intersecting the thickness direction of the electrode coating.

[0005] According to one embodiment of the present invention, the ratio of the OI value of the oriented region to the OI value of the non-oriented region is 0.002 to 0.75.

[0006] According to one embodiment of the present invention, the OI value of the oriented region is 0.1 to 15, preferably 0.2 to 5; and / or, the OI value of the non-oriented region is 20 to 40.

[0007] According to one embodiment of the present invention, the orientation coefficient λ of the electrode coating satisfies 0 < λ < 8, preferably 0.4 ≤ λ ≤ 2.5; wherein λ = L1 / L2, L1 is the width of the orientation region, and L2 is the width of the non-orientation region.

[0008] According to one embodiment of the present invention, the width L1 of the orientation region satisfies 0.05cm < L1 < 10cm; and / or, the width L2 of the non-orientation region satisfies 0 < L2 < 80cm, preferably 0.02cm < L2 < 25cm.

[0009] According to one embodiment of the present invention, the first direction is the length direction of the electrode coating.

[0010] According to one embodiment of the present invention, the particle size Dv50 of the electrode active material is 7 μm to 16 μm.

[0011] According to one embodiment of the present invention, the areal density of the electrode coating is 165 g m³. -2 ~280g m -2 ; and / or, the compaction density of the electrode coating is 1.48 cm³. -3 ~1.6g cm -3 ; and / or, the thickness of the electrode coating is 103 μm to 197 μm.

[0012] According to one embodiment of the present invention, the electrode sheet is a negative electrode sheet, and the electrode active material includes graphite.

[0013] According to one embodiment of the present invention, the electrode sheet is a positive electrode sheet, and the electrode active material includes a positive electrode ternary material and / or lithium iron phosphate.

[0014] In another aspect, the present invention provides a method for preparing the above-mentioned electrode sheet, comprising the following steps: coating a slurry containing the electrode active material onto the surface of the electrode current collector, forming a wet film on the surface of the electrode current collector to obtain an electrode precursor; passing the electrode precursor through a magnetic field, forming the oriented region and the non-oriented region during the process of the electrode precursor passing through the magnetic field, thereby obtaining the electrode sheet; wherein the magnetic field is provided by a magnetic component, the magnetic component comprising N-pole magnets and S-pole magnets staggered along a fourth direction, and the direction of movement of the electrode precursor when passing through the magnetic field intersecting with or parallel to the fourth direction.

[0015] According to one embodiment of the present invention, during the process of passing the electrode precursor through the magnetic field, the moving speed of the electrode precursor is 1 m / min to 5 m / min; and / or, during the process of passing the electrode precursor through the magnetic field, the distance between the electrode precursor and the magnetic component is 0.5 cm to 5 cm; and / or, during the process of passing the electrode precursor through the magnetic field, the magnetic component is present on both opposite sides of the electrode precursor in the thickness direction; and / or, in the magnetic component, the spacing between adjacent N-pole magnets and S-pole magnets is 0 to 0.5 cm; and / or, the width of the N-pole magnet in the fourth direction is 1 cm to 2 cm; and / or, the width of the S-pole magnet in the fourth direction is 1 cm to 2 cm.

[0016] In another aspect, the present invention provides a battery comprising the above-described electrode sheet or an electrode sheet prepared according to the above-described electrode sheet preparation method.

[0017] In another aspect, the present invention provides a battery pack including the battery described above.

[0018] In another aspect, the present invention provides an electrical device comprising the aforementioned battery or battery pack.

[0019] The implementation of this invention has at least the following beneficial effects: The electrode coating of the electrode sheet includes oriented and non-oriented regions arranged alternately in a first direction (the first direction intersects with the thickness direction of the electrode coating). The OI value of the oriented region is lower than that of the non-oriented region. In this way, the electrode active material in the oriented region has a good degree of orientation, which is conducive to the embedding of active ions such as lithium ions into the electrode active material. This can promote the rapid transport of active ions such as lithium ions in the electrode sheet, reduce the liquid phase diffusion impedance of the electrode sheet and the internal resistance of the battery, and improve the fast charging capability of the battery. At the same time, the non-oriented region has a relatively high OI value, and the degree of orientation of the electrode active material in the non-oriented region is lower than that in the oriented region. This can alleviate the severe expansion and contraction of the electrode sheet caused by the excessively high orientation of the electrode active material during battery charging and discharging, as well as the problems of electrode active material detachment and peeling that occur easily during long battery cycles. This can improve the cycle stability of the battery. Attached Figure Description

[0020] Figure 1 This is a schematic diagram showing the arrangement direction of the N-pole magnet and the S-pole magnet of a magnetic component according to an embodiment of the present invention, and the moving direction of the pole piece front body.

[0021] Figure 2 This is a schematic diagram showing the arrangement direction of the N-pole magnet and the S-pole magnet of a magnetic component according to another embodiment of the present invention, and the moving direction of the pole piece front body.

[0022] Figure 3 This is a schematic diagram showing the arrangement direction of the N-pole magnet and the S-pole magnet of a magnetic component according to another embodiment of the present invention, and the moving direction of the pole piece front body.

[0023] Figure 4 This is a schematic diagram showing the relative positional relationship between the magnetic component and the electrode precursor according to an embodiment of the present invention;

[0024] Figure 5 This is a schematic diagram of the structure of an electrode sheet according to an embodiment of the present invention;

[0025] Figure 6 This is a photograph of the surface of the electrode coating according to an embodiment of the present invention.

[0026] Explanation of reference numerals in the attached figures: 1: Electrode current collector; 2: Electrode coating; 21: Oriented region; 22: Non-oriented region; 2': Wet film; 3: Electrode 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: Direction of movement of the electrode precursor; e: Direction of magnetic field; H: Distance between the electrode precursor and the magnetic component; L: Spacing between adjacent N-pole magnets and S-pole magnets. Detailed Implementation

[0027] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below. The specific embodiments listed below are merely descriptions of the principles and features of the present invention, and the examples are only for explaining the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] This invention provides an electrode sheet, such as... Figures 1 to 6 As shown, the electrode sheet 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 includes an electrode active material. The electrode coating 2 includes oriented regions 21 and non-oriented regions 22 arranged alternately in a first direction a. The OI value of the oriented region 21 is less than the OI value of the non-oriented region 22. The first direction a intersects with the thickness direction (third direction c) of the electrode coating 2.

[0029] According to the inventors' research, in the above-mentioned electrode sheet system, the orientation region 21 has a smaller OI value, and the electrode active material therein is more regularly oriented, exhibiting a higher degree of orientation. The orientation of the electrode active material particles in the local area (i.e., the orientation region 21 in the electrode coating 2) can reduce the tortuosity in the orientation region 21, improving the transport capability of active ions such as lithium ions. At the same time, the non-oriented region 22 can alleviate problems such as the single reverse expansion and contraction of electrode active material particles and the resulting shedding of electrode active material, thereby improving the long-term cycle stability and other performance characteristics of the battery. Therefore, the embodiments of the present invention can reduce battery impedance, improve battery fast charging capability (short-term charging capability), and simultaneously improve battery cycle stability and other performance characteristics.

[0030] Furthermore, in this embodiment of the invention, the electrode coating 2 forms an orientation region 21 in a local area and a non-orientation region 22 in a local area. This 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 electrode sheet preparation.

[0031] Further research revealed that the ratio of the OI value of the oriented region 21 to the OI value of the non-oriented region 22 can be 0.002 to 0.75, for example, a range consisting of 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 any two of these ranges. This approach helps to further improve the cycle stability of the battery and reduce its impedance.

[0032] In the aforementioned electrode sheet, the electrode active material exists in the form of particles, which can be spherical, near-spherical, or other regular or irregular shapes. The OI value indicates the degree of orientation of the crystal structure of the electrode active material particles. The smaller the OI value, the closer the direction of lithium ion embedding in the crystal structure of the electrode active material particles is to perpendicularity. That is, the higher the perpendicularity of the electrode active material particles in electrode coating 2, the better it is to reduce tortuosity and the stronger the ion diffusion ability.

[0033] Relatively speaking, the smaller the OI value of the orientation region 21, the higher the orientation degree (perpendicularity) of the electrode active material therein, which is more conducive to the transport of active ions such as lithium ions. However, if the OI value of the orientation region 21 is too small, it will also increase the expansion degree of the electrode active material to a certain extent, affecting the battery cycle stability and other performance. Taking these factors into consideration, in some embodiments, the OI value of the orientation region 21 can be 0.1 to 15, for example, 0.1, 0.2, 0.5, 0.8, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 13, 15 or any two of them, preferably 0.2 to 5, which is conducive to further improving the cycle stability of the battery and reducing the battery impedance.

[0034] In addition, the OI value of the non-oriented region 22 can be 20 to 40, for example, a range of 20, 23, 25, 28, 30, 33, 35, 38, 40 or any two of them, which is beneficial to further improve the cycle stability of the battery and reduce the battery impedance.

[0035] In this embodiment of the invention, there are multiple oriented regions 21 and multiple non-oriented regions 22. These oriented regions 21 and non-oriented regions 22 are arranged alternately along the first direction a (i.e., the direction from the oriented region 21 to the non-oriented region 22 is parallel to the first direction a). That is, in the first direction a, there is one non-oriented region 22 between every two adjacent oriented regions 21 (i.e., every two adjacent oriented regions 21 are separated by a non-oriented region 22), and there is one oriented region 21 between every two adjacent non-oriented regions 22 (i.e., every two adjacent non-oriented regions 22 are separated by an oriented region 21). Specifically, oriented regions 21 and non-oriented regions 22 can be arranged alternately along the entire first direction a of the electrode coating 2. The appearance of the electrode coating 2 generally presents as alternating light and dark stripes (e.g., ...). Figure 6 As shown, generally darker stripes ( Figure 6 The black area in the middle) is orientation area 21, with more obvious stripes ( Figure 6 The gray area in the image is the non-oriented region (22).

[0036] Specifically, such as Figure 4 and Figure 5 As shown, the thickness direction of electrode coating 2 (which is also the thickness direction of the electrode sheet) is parallel to the third direction c, and the first direction a intersects the thickness direction of electrode coating 2, and the two can be substantially perpendicular. For example, the first direction a can be the width direction of electrode coating 2 (which is also the width direction of the electrode sheet), specifically, the oriented regions 21 and non-oriented regions 22 can be staggered along the entire width direction of electrode coating 2; or, the first direction a can be the length direction of electrode coating 2, specifically, the oriented regions 21 and non-oriented regions 22 can be staggered along the entire length direction of electrode coating 2.

[0037] In contrast, when the first direction a is the length direction of the electrode coating 2 (i.e., the oriented region 21 and the non-oriented region 22 are staggered in the length direction of the electrode coating 2), it is beneficial to balance the performance of reducing battery impedance and improving battery cycle stability, while also facilitating the preparation of electrode sheets and improving the preparation efficiency and yield of electrode sheets.

[0038] According to further research by the inventors, the orientation coefficient λ of the electrode coating 2 can satisfy 0 < λ < 8, preferably 0.4 ≤ λ ≤ 2.5; λ = L1 / L2, where L1 is the width of the orientation region 21 and L2 is the width of the non-orientation region 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.

[0039] For example, λ can be a range consisting of 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 any two of them.

[0040] In some embodiments, the width L1 of the orientation region 21 satisfies 0.05cm < L1 < 10cm, which is beneficial to further improve the cycle stability of the battery and reduce the battery impedance.

[0041] For example, the width L1 of the orientation region 21 can be a range of 0.07cm, 0.1cm, 0.3cm, 0.5cm, 0.8cm, 1cm, 1.2cm, 1.5cm, 2cm, 3cm, 4cm, 5cm, 6cm, 7cm, 8cm, 9cm, 10cm or any two of these.

[0042] In some embodiments, the width L2 of the non-oriented region 22 satisfies 0cm < L2 < 80cm. 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 0.02cm < L2 < 25cm, which is beneficial for further improving the cycle stability of the battery and reducing the battery impedance.

[0043] In this embodiment of the invention, 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.

[0044] 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).

[0045] 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.

[0046] 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 / m2 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.

[0047] 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 / cm³ 3 1.5g / cm 3 1.53g / cm 3 1.55g / cm 3 1.58g / cm 3 1.6g / cm 3 or a range consisting of any two of them.

[0048] Furthermore, the thickness of the electrode coating 2 can be from 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 any combination thereof.

[0049] In this embodiment of the invention, the thickness of the electrode coating 2 (103-197 μm) refers to the total thickness of the electrode coating 2 disposed on the surface of the electrode current collector 1, that is, 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 coating 2 is disposed on both the front and back surfaces of the electrode current collector 1, the total thickness of the electrode coating 2 = the thickness of the electrode coating 2 on one side of the electrode current collector 1 + the thickness of the electrode coating 2 on the other side of the electrode current collector 1. The thickness of the electrode coating 2 is approximately equal to the ratio of the areal density of the electrode coating 2 to the compaction density of the electrode coating 2 (i.e., the thickness of the electrode coating 2 = the areal density of the electrode coating 2 / the compaction density of the electrode coating 2).

[0050] In some embodiments, the electrode sheet can be a negative electrode sheet, and correspondingly, the electrode current collector 1 is a negative electrode current collector, the electrode coating 2 is a negative electrode coating (negative electrode active material layer), and the electrode active material is a negative electrode active material, which may include graphite.

[0051] The embodiments of the present invention may employ conventional negative electrode current collectors in the art, for example, negative electrode current collectors include copper foil.

[0052] In other embodiments, the electrode sheet is a positive electrode sheet, and correspondingly, the electrode current collector 1 is a positive electrode current collector, the electrode coating 2 is a positive electrode coating (positive electrode active material layer), and the electrode active material is a positive electrode active material, which may include a positive electrode ternary material and / or lithium iron phosphate, wherein the positive electrode ternary material includes, for example, nickel cobalt manganese ternary material and / or nickel cobalt aluminum ternary material.

[0053] The embodiments of the present invention may employ conventional positive current collectors in the art, for example, positive current collectors may include aluminum foil.

[0054] In this embodiment of the invention, an electrode coating 2 can be provided on one side surface of the electrode current collector 1, or an electrode coating 2 can be provided on both sides of the electrode current collector 1. When an electrode coating 2 is provided on both sides of the electrode current collector 1, the electrode coating 2 on one side surface can be the electrode coating 2 including the staggered orientation regions 21 and non-orientation regions 22, or the electrode coating 2 on both sides of the electrode current collector 1 can be the electrode coating 2 including the staggered orientation regions 21 and non-orientation regions 22.

[0055] Generally, the electrode coating 2 also includes a conductive agent and a binder. Based on the total mass of the electrode coating 2, 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 any combination thereof. 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 any combination thereof. 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 any combination thereof.

[0056] In this embodiment of the invention, the conductive agent in the electrode coating 2 can be a conventional conductive material in the art, such as one or more of carbon black, carbon nanotubes (CNT), acetylene black, graphene, Ketjen black, and carbon fiber.

[0057] In this embodiment of the invention, the binder in the electrode coating 2 can be a conventional adhesive material in the art. For example, when the electrode sheet is a negative electrode sheet, the binder may include one or more of the following: sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, 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 may include one or more of the following: polyvinylidene fluoride (PVDF), polyvinylidene fluoride, polyvinyl fluoride, polyethylene, polypropylene, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, ethylene oxide-containing polymers, polyvinylpyrrolidone, and polyurethane.

[0058] This invention also provides a method for preparing the above-mentioned electrode sheet, such as... Figures 1 to 4 As shown, the preparation method includes the following steps: coating a slurry containing electrode active material onto the surface of the electrode current collector 1 to form a wet film 2' on the surface of the electrode current collector 1, thus obtaining an electrode precursor 3; passing the electrode precursor 3 through a magnetic field, forming an orientation region 21 and a non-orientation region 22 during the process of the electrode precursor 3 passing through the magnetic field, thereby obtaining an electrode sheet; wherein, the magnetic field is provided by a magnetic component, which includes N-pole magnets and S-pole magnets staggered along the fourth direction x, and the direction d of movement of the electrode precursor (i.e., the electrode current collector 1 with the wet film 2') 3 when passing through the magnetic field intersects with the fourth direction x (specifically, they can be perpendicular to each other, e.g., ...). Figure 1 (as shown), or parallel to the fourth direction x (such as...) Figure 2 , Figure 3 and Figure 4 (As shown).

[0059] In the above preparation process, as the electrode precursor 3 passes through the magnetic field, the magnetic component applies a magnetic field. The direction of the magnetic field e intersects (for example, it can be basically perpendicular) the direction of movement d of the electrode precursor 3 when it passes through the magnetic field. The magnetic component is composed of N-pole magnets and S-pole magnets arranged alternately along the fourth direction x. The magnetic field generated by the magnetic component has different magnetic field strengths in different regions, that is, 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 the magnetic field, the magnetic field regions with different magnetic field strengths induce the formation of regions with different orientation degrees, thereby forming an oriented region 21 and a non-oriented region 22 arranged alternately along the first direction a on the electrode coating 2 of the prepared electrode sheet.

[0060] Generally, the maximum magnetic field strength of the above-mentioned magnetic field (i.e., the magnetic field strength of the region with the largest magnetic field strength) can be 0.5 to 0.8 T, for example, 0.5 T, 0.6 T, 0.7 T, 0.8 T or any combination thereof.

[0061] Specifically, during the process of the electrode precursor 3 passing through the magnetic field, the moving speed (travel speed) of the electrode precursor 3 can be 1m / min to 5m / min, for example, a range of 1m / min, 2m / min, 3m / min, 4m / min, 5m / min or any two of them.

[0062] Specifically, such as Figure 4 As shown, during the process of the electrode precursor 3 passing through the magnetic field, the thickness direction of the electrode precursor 3 ( Figure 4 Magnetic components are present on both sides of the third direction c) in the middle, that is, a magnetic field region with a magnetic field is formed between the magnetic components on both sides of the thickness direction of the electrode precursor 3, so that the electrode precursor 3 passes through the magnetic field region, thereby realizing the electrode precursor 3 passing through the magnetic field.

[0063] The thickness direction of the electrode precursor 3 intersects with the moving direction d of the electrode precursor 3. Specifically, the thickness direction of the electrode precursor 3 can be basically perpendicular to the moving direction d of the electrode precursor 3, and the moving direction of the electrode precursor 3 can be basically parallel to the length direction of the electrode precursor 3 (which is also the length direction of the electrode sheet obtained).

[0064] Specifically, such as Figure 4 As shown, during the process of the electrode precursor 3 passing through the magnetic field, the distance H between the electrode precursor 3 and the magnetic component (i.e., the vertical height of the electrode precursor relative to the magnetic component) can be 0.5cm to 5cm, for example, 0.5cm, 1cm, 2cm, 3cm, 4cm, 5cm or any combination thereof.

[0065] In embodiments of the present invention, such as Figure 4 As shown, the distance H between the electrode precursor 3 and the magnetic component refers to the distance from the electrode precursor 3 to the magnetic component located on either side of the electrode precursor 3 in the third direction c.

[0066] Under normal circumstances, such as Figures 1 to 4 As shown, any magnetic component includes multiple N-pole magnets and multiple S-pole magnets. These N-pole magnets and S-pole magnets are arranged alternately in the fourth direction x. There is one S-pole magnet between every two adjacent N-pole magnets and one N-pole magnet between every two adjacent S-pole magnets.

[0067] In addition, such as Figures 1 to 4 As shown, in the magnetic assembly, the distance L between adjacent N-pole magnets and S-pole magnets can be essentially 0 (the N-pole magnets and S-pole magnets are arranged closely together, such as...). Figure 3 and Figure 4 (as shown), or, the distance L between adjacent N-pole magnets and S-pole magnets is greater than 0 (i.e., there is a gap between adjacent N-pole magnets and S-pole magnets, such as...). Figure 1 and Figure 2 (As shown).

[0068] In some embodiments, the distance L between adjacent N-pole magnets and S-pole magnets can be 0 to 0.5 cm, for example, a range of 0, 0.1 cm, 0.2 cm, 0.3 cm, 0.4 cm, 0.5 cm or any two of these.

[0069] In this embodiment of the invention, the distance L between adjacent N-pole magnets and S-pole magnets refers to the distance between any N-pole magnet and the adjacent S-pole magnet in the fourth direction x (also the distance between any S-pole magnet and the adjacent N-pole magnet in the fourth direction x).

[0070] Specifically, such as Figures 1 to 3 As shown, for each N-pole magnet, the N-pole magnet may include multiple N-pole magnetic blocks arranged along the fifth direction y. These N-pole magnetic blocks are generally arranged closely (i.e., the distance between two adjacent N-pole magnetic blocks in the fifth direction y is 0), thereby forming an N-pole magnet.

[0071] Specifically, such as Figures 1 to 3 As shown, for each S-pole magnet, the S-pole magnet may include multiple S-pole magnetic blocks arranged along the fifth direction y. These S-pole magnetic blocks are generally arranged closely (i.e., the distance between two adjacent S-pole magnetic blocks in the fifth direction y is 0), thereby forming an S-pole magnet.

[0072] Specifically, the fifth direction y intersects the fourth direction x, and the two can be basically perpendicular; the fifth direction y intersects the third direction c, and the two can be basically perpendicular; the fourth direction x intersects the third direction c, and the two can be basically perpendicular.

[0073] Furthermore, the width of the N-pole magnet in the fourth direction x can be 1cm to 2cm, and the width of the S-pole magnet in the fourth direction can also be 1cm to 2cm. The widths of the N-pole magnet and the S-pole magnet in the fourth direction x can be the same (e.g., ...). Figures 1 to 4 (As shown).

[0074] In this embodiment of the invention, the width of an N-pole magnet in the fourth direction x refers to the width of an N-pole magnet in the fourth direction x, which is equal to the width of any N-pole magnetic block forming the N-pole magnet in the fourth direction x; the width of an S-pole magnet in the fourth direction x refers to the width of an S-pole magnet in the fourth direction x, which is equal to the width of any S-pole magnetic block forming the S-pole magnet in the fourth direction x.

[0075] In some embodiments, for any N-pole magnetic block forming an N-pole magnet, the length L of its cross-section parallel to the fifth direction y is... N It can be 1cm to 2cm, with a width of W.N It can be 1cm to 2cm (i.e., the size of the N pole magnet is L). N *W N ).

[0076] In some embodiments, for any S-pole magnetic block forming an S-pole magnet, the length L of its cross-section parallel to the fifth direction y is... s It can be 1cm to 2cm, with a width of W. s It can be 1cm to 2cm (that is, the size of the S pole magnet is L). s *W s ).

[0077] Specifically, the width and other dimensions of the N-pole magnet and the S-pole magnet can be approximately equal.

[0078] Specifically, the electrode precursor 3 can be dried simultaneously while passing through the magnetic field. That is, the magnetic component can be placed in an oven for drying the wet film 2' to provide a magnetic field. The electrode precursor 3 enters the oven and is dried while passing through the magnetic field. Alternatively, the electrode precursor 3 can be dried after passing through the magnetic field, for example, by entering an oven for drying. After drying, it is then rolled (cold pressed) to form the electrode coating 2 with the staggered orientation regions 21 and non-orientation regions 22 on the surface of the electrode current collector 1. Then, through processes such as slitting and cutting, the electrode sheet is obtained.

[0079] In a specific implementation, a slurry containing electrode active material can be coated on the opposite sides of the electrode current collector 1 in the thickness direction (i.e., the two surfaces of the electrode current collector 1), so as to form a wet film 2' on both the front and back surfaces of the electrode current collector 1, thus obtaining an electrode precursor 3; after the electrode precursor 3 is passed through a magnetic field and undergoes drying, rolling and other processes, an electrode coating 2 with staggered orientation regions 21 and non-orientation regions 22 is formed on both the front and back surfaces of the electrode current collector 1, thus obtaining an electrode sheet.

[0080] In this embodiment of the invention, a slurry containing electrode active materials can be prepared using conventional methods in the art. For example, when the electrode sheet is a negative electrode sheet, the components used to form the negative electrode coating, such as the negative electrode active material, conductive agent, and binder, can be dispersed in a first solvent, such as deionized water and / or N-methylpyrrolidone (NMP), to prepare a negative electrode slurry (i.e., a slurry containing electrode active materials). This slurry is then coated onto the surface of the negative electrode current collector, and after processes such as magnetic field induction, drying, rolling, slitting, and cutting, a negative electrode sheet is obtained. When the electrode sheet is a positive electrode sheet, the components used to form the positive electrode coating, such as the positive electrode active material, conductive agent, and binder, can be dispersed in a second solvent, such as N-methylpyrrolidone (NMP), to prepare a positive electrode slurry (i.e., a slurry containing electrode active materials). This slurry is then coated onto the surface of the positive electrode current collector, and after processes such as magnetic field induction, drying, rolling, slitting, and cutting, a positive electrode sheet is obtained.

[0081] In this embodiment of the invention, the processes involved, such as coating, drying, rolling, slitting, and cutting, are all conventional processes in the art for preparing electrode sheets by coating method, and there are no special limitations on them.

[0082] This invention also provides a battery comprising the above-described electrode sheet or an electrode sheet prepared according to the above-described electrode sheet preparation method. This battery has advantages corresponding to the above-described electrode sheet, which will not be elaborated further.

[0083] The battery in this embodiment of the invention can be a lithium-ion battery (such as a lithium-ion power battery), a solar cell, or other novel energy storage battery.

[0084] Generally, a battery includes an electrolyte, a battery cell, and a package containing the battery cell. The electrolyte is injected into the battery cell within the package. The battery cell includes a positive electrode, a negative electrode, and a separator located between the positive and negative electrodes. The battery cell can be a stacked cell, meaning it is composed of alternating layers of positive electrode, separator, and negative electrode; or it can be a wound cell, where the positive electrode, separator, and negative electrode are sequentially stacked and then wound to form a cell with a wound structure.

[0085] In this embodiment of the invention, the positive electrode sheet may be the electrode sheet with the aforementioned staggered arrangement of orientation regions 21 and non-orientation regions 22 (i.e., the positive electrode coating includes the aforementioned staggered arrangement of orientation regions 21 and non-orientation regions 22), or the negative electrode sheet may be the electrode sheet with the aforementioned staggered arrangement of orientation regions 21 and non-orientation regions 22 (i.e., the negative electrode coating includes the aforementioned staggered arrangement of orientation regions 21 and non-orientation regions 22), or both the positive electrode sheet and the negative electrode sheet may be the aforementioned electrode sheet with the aforementioned staggered arrangement of orientation regions 21 and non-orientation regions 22.

[0086] The electrolyte in this embodiment of the invention can be a conventional electrolyte in the art. For example, the electrolyte is a non-aqueous electrolyte, which may specifically include organic solvents, additives, and electrolyte salts. Organic solvents include one or more of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), and diethyl carbonate. Additives may include vinylene carbonate (VC) and / or fluoroethylene carbonate (FEC). Electrolyte salts may include lithium salts, such as lithium hexafluorophosphate (LiPF6) and / or lithium bis(fluorosulfonyl)imide (LiFSI), but are not limited thereto.

[0087] In this embodiment of the invention, the separator is used to separate the positive electrode and the negative electrode to prevent the positive electrode and the negative electrode from short-circuiting due to contact. Conventional separators in the art can be used in this embodiment of the invention, and there are no special limitations on this.

[0088] In this embodiment of the invention, the battery cell can be packaged using conventional encapsulation (shell) materials in the art. 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 encapsulation can include an aluminum-plastic film.

[0089] The embodiments of the present invention can assemble components such as positive electrode, separator and negative electrode into a battery using conventional methods in the art. For example, the positive electrode, separator and negative electrode can be made into a cell (e.g., wound to form a wound cell), placed in a casing, dried, and then injected with electrolyte. After vacuum sealing, standing, formation and shaping processes, a lithium-ion battery is obtained. These processes are all conventional operations in the art and are not particularly limited.

[0090] This invention also provides a battery pack including the battery described above, which has advantages corresponding to the electrode plates described above, and will not be described in detail here.

[0091] Generally, a battery pack includes multiple batteries as individual cells, which are connected to form the battery pack. These batteries can be electrically connected using methods conventional in the art, such as series connection, parallel connection, or a combination of these connection methods, without any particular limitation.

[0092] This invention also provides an electrical device, including the battery or battery pack described above. This electrical device has advantages corresponding to the electrode plates described above, which will not be elaborated further.

[0093] The electrical equipment in the embodiments of the present invention can be conventional electrical equipment in the art, such as power equipment (e.g., electric vehicles, electric cars), electronic equipment (e.g., mobile phones, tablets, laptops, digital cameras, etc.), wearable devices (e.g., watches, bracelets, VR glasses, etc.), and there are no particular limitations.

[0094] In this embodiment of the invention, X-ray diffraction (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 results of a certain region of the electrode coating 2, I1 is the integral value of the XRD peak area in the direction in which active ions (such as lithium ions) are embedded in the crystal structure of the electrode active material particles, and I2 is the integral value of the XRD peak area in the crystal direction that is perpendicular to I1 and where active ions are less likely to be embedded (that is, the crystal direction in which active ions are less likely to be embedded is perpendicular to the direction in which active ions are embedded in the crystal structure of the electrode active material particles). Then, the orientation value of the internal crystal structure of the electrode active material particles (i.e., the OI value of the electrode active material) = I2 / I1, and the OI value > 0. Taking the negative electrode sheet using graphite as the negative electrode active material as an example, XRD analysis was performed on each region of the negative electrode coating. In the XRD analysis results, I1 is the peak area of ​​the 110 crystal orientation of graphite, I2 is the peak area of ​​the 004 crystal orientation of graphite, and the OI value of graphite = I2 / I1. The OI value of graphite can characterize the degree of order of the arrangement of graphite particles crystal structure (the smaller the OI value, the higher the degree of order (perpendicularity)).

[0095] In this embodiment of the invention, the test process for the areal density of the electrode coating 2 may include: taking an electrode sheet sample, testing the total mass m1 of the electrode sheet sample, and the surface area S of one side of the electrode sheet sample in the thickness direction; 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 areal density of the electrode coating 2 = (m1-m2) / S.

[0096] In this embodiment of the invention, the compaction density of electrode coating 2 = the areal density of electrode coating 2 / the total thickness of electrode coating 2. The test process for the areal density of electrode coating 2 is as described above. The test process for the total thickness of electrode coating 2 may include: taking an electrode sheet sample and testing the total thickness T1 of the electrode sheet sample (T1 = the total thickness of electrode coating 2 + the thickness of electrode current collector 1. When electrode coating 2 is provided on both the front and back surfaces of electrode current collector 1, the total thickness of electrode coating 2 = the thickness of electrode coating 2 on one side of electrode current collector 1 + the thickness of electrode coating 2 on the other side of electrode current collector 1); then scraping off the electrode coating 2 on the electrode sheet sample and testing the thickness T2 of the obtained electrode current collector 1. Then the total thickness of electrode coating 2 = T1 - T2.

[0097] In practice, a 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.

[0098] In this embodiment of the invention, the particle size Dv50 of the electrode active material represents the particle size that reaches 50% of the total volumetric particle size in the volumetric particle size distribution of the electrode active material. The particle size Dv50 of the electrode active material can be measured using 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 is dispersed evenly in water, then filtered, and the resulting solid particle product is dried. The particle size Dv50 of this solid particle product is then measured using a laser particle size analyzer, and the test result is the particle size Dv50 of the electrode active material.

[0099] In practice, the battery can be disassembled to obtain the electrode sheet, and then the OI value of different regions in the electrode coating 2 of the electrode sheet, as well as 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.

[0100] The present invention will be further described below through specific embodiments. In the following embodiments, the testing process for parameters such as the areal density and compaction density of the electrode coating 2, and the XRD test of graphite (graphite OI value = I2 / I1, where I1 is the 110 crystal orientation peak area of ​​graphite and I2 is the 004 crystal orientation peak area of ​​graphite) is the same as described above, and will not be repeated below.

[0101] Unless otherwise specified, the electrolytes used in the following examples and comparative examples were prepared according to the following process:

[0102] In an argon-atmosphere glove box with a water content of <1 ppm and an oxygen content of <1 ppm, DMC, EMC, EC, VC, FEC, LiPF6, and LiFSI were mixed to prepare an electrolyte. 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 was 0.1%, the mass percentage of LiPF6 was 7.9%, and the mass percentage of LiFSI was 5%.

[0103] Example 1

[0104] 1. Preparation of positive electrode sheet

[0105] Lithium iron phosphate (LiFePO4), carbon nanotubes (CNTs), and polyvinylidene fluoride were mixed in a mass ratio of 97.3:0.8:1.9. N-methylpyrrolidone (NMP) was added, and the mixture was stirred under vacuum until a homogeneous positive electrode slurry was formed. The positive electrode slurry was then uniformly coated onto both the front and back surfaces of the positive electrode current collector aluminum foil. After drying at 100°C, the positive electrode sheet was obtained by cold pressing, slitting, cutting, and then drying under vacuum at 100°C for 4 hours.

[0106] 2. Preparation of negative electrode sheet

[0107] (1) Graphite, carbon black, styrene-butadiene rubber (SBR), and sodium carboxymethyl cellulose (CMC) are thoroughly mixed in deionized water at a mass ratio of 95:1:3:1 to form a uniform negative electrode slurry; the negative electrode slurry is coated on both the front and back surfaces of the negative electrode current collector copper foil to form wet films 2' on both the front and back surfaces of the copper foil, thus obtaining the electrode precursor 3;

[0108] (2) The magnetic component is placed in the oven to provide a magnetic field in the oven. The electrode precursor 3 enters the oven at a speed of 3 m / min and passes through the magnetic field while being dried.

[0109] Among them, the moving direction d of the electrode precursor 3 is perpendicular to the fourth direction x.

[0110] Among them, magnetic components are present on both sides of the thickness direction (third direction c) of the electrode precursor 3. Each magnetic component is composed of multiple N-pole magnets and multiple S-pole magnets arranged alternately and closely in the fourth direction x (the distance L between adjacent N-pole magnets and S-pole magnets is 0).

[0111] Each N-pole magnet is composed of multiple N-pole magnetic blocks arranged closely along the fifth direction y. The dimensions of each N-pole magnetic block are 1cm*1cm (i.e., the length L of the cross-section of the N-pole magnetic block parallel to the fifth direction y). N =1cm, width W N =1cm).

[0112] Each S-pole magnet is composed of multiple S-pole magnetic blocks arranged closely along the fifth direction y. The dimensions of each S-pole magnetic block are 1cm*1cm (i.e., the length L of the cross-section of the S-pole magnetic block parallel to the fifth direction y). s =1cm, width W s =1cm).

[0113] The distance between the electrode precursor 3 and the magnetic component (i.e., the vertical height of the electrode precursor 3 relative to the magnetic component) H = 0.5 mm.

[0114] (3) The electrode precursor 3 after passing through the oven is dried and cold-pressed so that the wet film 2' on the positive and negative surfaces of the copper foil forms a negative electrode coating. After slitting and cutting, the negative electrode sheet is obtained.

[0115] The areal density of the negative electrode coating is 230 g / m³. 2 The compacted density is 1.55 g / cm³. 3 .

[0116] Among them, the negative electrode coating of the negative electrode sheet has oriented regions 21 and non-oriented regions 22 interleaved along the first direction a (see surface photograph of the negative electrode coating). Figure 6 ).

[0117] 3. Preparation of lithium-ion batteries

[0118] The positive electrode, separator, and negative electrode are stacked in sequence, with the separator acting as a separator between the positive and negative electrodes. They are then wound up and placed in an outer packaging foil (aluminum-plastic film). After drying, the electrolyte prepared above is injected into it. Then, the lithium-ion battery is produced through vacuum sealing, settling, formation, and shaping processes.

[0119] Examples 2 to 21 differ from Example 1 in that the relevant parameters of the negative electrode sheet (graphite particle size Dv50, OI value of the orientation region 21 (OI1 in Table 1), OI value of the non-orientation region 22 (OI2 in Table 1), ratio of OI value of the orientation region 21 to OI value of the non-orientation region 22 (OI1 / OI2 in Table 1), orientation coefficient λ, width L1 of the orientation region 21), and relevant parameters in the negative electrode sheet preparation process (vertical height H of the electrode precursor 3 relative to the magnetic component, moving speed of the electrode precursor 3, moving direction d of the electrode precursor 3, spacing L between adjacent N-pole magnets and S-pole magnets, size of S-pole and N-pole magnets) are different. See Table 1 (relevant parameters in the negative electrode sheet preparation process) and Table 2 (relevant parameters of the negative electrode sheet) for details. Except for the differences shown in Table 1 and Table 2, the other conditions are the same.

[0120] 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.

[0121] 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.

[0122] 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.

[0123] (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.

[0124] (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).

[0125] (3) Liquid phase diffusion impedance test: The two negative electrode plates and the separator are assembled in sequence to form the electrode core (the separator is located between the two negative electrode plates); the electrode core is placed in the outer packaging shell (aluminum-plastic film), baked, and electrolyte is injected into it. After encapsulation, wetting and other processes, a liquid phase diffusion impedance battery is obtained. The liquid phase diffusion impedance of the battery is tested using a CHI Chenhua electrochemical workstation in the frequency range of 300000Hz-0.05Hz.

[0126] Table 1. Relevant parameters during electrode fabrication.

[0127]

[0128] 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 1cm*1cm, which means that the size of the N-pole magnetic block and the S-pole magnetic block are both 1cm*1cm.

[0129] Table 2. Relevant parameters of the negative electrode.

[0130]

[0131] Table 3 Performance test results of lithium-ion batteries

[0132] Example 50% SOC DCIR(Ω) Liquid phase diffusion resistance (Ω) Capacity retention Example 1 0.6 0.366 91.50％ Example 2 0.787 0.434 92.20％ Example 3 0.574 0.329 94％ Example 4 0.594 0.345 93.80％ Example 5 0.57 0.34 94％ Example 6 0.847 0.455 89.90％ Example 7 1.224 0.582 90.10％ Example 8 0.588 0.337 82.10％ Example 9 0.621 0.387 93.60％ Example 10 0.879 0.493 83.30％ Example 11 0.652 0.393 94.20％ Example 12 0.988 0.549 94.30％ Example 13 1.152 0.576 91.80％ Example 14 1.300 0.597 91.10％ Example 15 0.679 0.399 90.30％ Example 16 0.689 0.411 91％ Example 17 0.669 0.383 88.90％ Example 18 0.597 0.403 86.60％ Example 19 0.6 0.395 90.70％ Example 20 0.913 0.405 93.40％ Example 21 1.045 0.432 93.70％ Comparative Example 1 1.436 0.601 87.1％ Comparative Example 2 0.506 0.329 79.1％

[0133] As can be seen, in Comparative Example 1, the OI value of the negative electrode coating is 39, the liquid phase diffusion resistance of the negative electrode is high (>0.6Ω), and the internal resistance of the battery is high (the 50% SOC DCIR of the battery is 1.436Ω). In Comparative Example 2, the OI value of the negative electrode coating is 0.1. Although it can reduce the liquid phase diffusion resistance of the negative electrode and the internal resistance of the battery to a certain extent, the cycle stability of the battery is severely deteriorated (the capacity retention rate is low, 79.1%). Compared with Comparative Examples 1 and 2, in the negative electrode of Examples 1 to 21, the negative electrode coating includes staggered oriented and non-oriented regions. The OI value of the oriented region is lower than that of the non-oriented region, which enables the negative electrode and the battery to have both lower impedance and higher cycle stability (the liquid phase diffusion resistance of the negative electrode is not higher than 0.597Ω, the 50% SOC DCIR of the battery is not higher than 1.3Ω, and the cycle capacity retention rate of the battery is not lower than 82%), and the battery has good fast charging performance and cycle life.

[0134] Furthermore, compared to Example 14, Examples 1-3, 8, and 11-14, by controlling the OI value of the oriented region within the range of 0.1-15 and the ratio of the OI value of the oriented region to the OI value of the non-oriented region within the range of 0.002-0.75, are beneficial for further reducing the liquid phase diffusion impedance of the negative electrode and the internal resistance of the battery, while maintaining a high capacity retention rate. In particular, Examples 1-3 and 11, by further controlling the OI value of the oriented region within the range of 0.2-5, are beneficial for more significantly reducing the liquid phase diffusion impedance of the negative electrode (not higher than 0.493Ω) and the internal resistance of the battery (the 50% SOC DCIR of the battery is not higher than 0.787Ω), and maintaining a higher capacity retention rate of the battery (not lower than 91.5%).

[0135] Furthermore, compared to Example 10, Examples 3-6, 9, and 15-17, by controlling the orientation coefficient λ of the negative electrode coating within the range of 0 < λ < 8, facilitate further reduction of the liquid phase diffusion impedance of the negative electrode sheet and the internal resistance of the battery, as well as improvement of the battery capacity retention rate. In particular, Examples 3-5, 9, and 15-17, by further controlling the orientation coefficient λ of the negative electrode coating within the range of 0.4 ≤ λ ≤ 2.5, facilitate a more significant reduction in the liquid phase diffusion impedance of the negative electrode sheet (not higher than 0.411Ω) and the internal resistance of the battery (50% SOC DCIR of the battery not higher than 0.689Ω), while maintaining a high battery capacity retention rate (not lower than 88.9%).

[0136] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An electrode sheet, characterized in that, The device includes an electrode current collector and an electrode coating located on at least one side surface of the electrode current collector, the electrode coating comprising an electrode active material; The electrode coating includes oriented and non-oriented regions arranged alternately in a first direction, wherein the OI value of the oriented region is smaller than the OI value of the non-oriented region, and the first direction intersects with the thickness direction of the electrode coating. The orientation coefficient λ of the electrode coating satisfies 0.4≤λ≤2.5, where λ=L1 / L2, L1 is the width of the orientation region, and L2 is the width of the non-orientation region; the OI value of the orientation region is 0.1~15, and the OI value of the non-orientation region is 20~40. The electrode sheet is a negative electrode sheet, and the electrode active material includes graphite.

2. The electrode sheet according to claim 1, characterized in that, The ratio of the OI value of the oriented region to the OI value of the non-oriented region is 0.005 to 0.

75.

3. The electrode sheet according to claim 1 or 2, characterized in that, The OI value of the orientation region is 0.2~5.

4. The electrode sheet according to claim 1 or 2, characterized in that, The width L1 of the orientation region satisfies 0.05cm < L1 < 10cm; And / or, the width L2 of the non-oriented region satisfies 0 < L2 < 80 cm.

5. The electrode sheet according to claim 3, characterized in that, The width L1 of the orientation region satisfies 0.05cm < L1 < 10cm; And / or, the width L2 of the non-oriented region satisfies 0 < L2 < 80 cm.

6. The electrode sheet according to claim 4, characterized in that, The width L2 of the non-oriented region satisfies 0.02 cm < L2 < 25 cm.

7. The electrode sheet according to claim 5, characterized in that, The width L2 of the non-oriented region satisfies 0.02 cm < L2 < 25 cm.

8. The electrode sheet according to claim 1 or 2, characterized in that, The first direction is the length direction of the electrode coating.

9. The electrode sheet according to claim 3, characterized in that, The first direction is the length direction of the electrode coating.

10. The electrode sheet according to claim 1 or 2, characterized in that, The particle size Dv50 of the electrode active material is 7μm~16μm.

11. The electrode sheet according to claim 3, characterized in that, The particle size Dv50 of the electrode active material is 7μm~16μm.

12. The electrode sheet according to claim 1 or 2, characterized in that, The areal density of the electrode coating is 165 g / m³. -2 ~280 gm -2 ; And / or, the compaction density of the electrode coating is 1.48 cm³. -3 ~1.6 g cm -3 ; And / or, the thickness of the electrode coating is 103 μm to 197 μm.

13. The electrode sheet according to claim 3, characterized in that, The areal density of the electrode coating is 165 g / m³. -2 ~280 gm -2 ; And / or, the compaction density of the electrode coating is 1.48 cm³. -3 ~1.6 g cm -3 ; And / or, the thickness of the electrode coating is 103 μm to 197 μm.

14. A method for preparing an electrode sheet according to any one of claims 1-13, characterized in that, Includes the following steps: A slurry containing the electrode active material is coated onto the surface of the electrode current collector to form a wet film on the surface of the electrode current collector, thereby obtaining an electrode precursor. The electrode precursor is passed through a magnetic field, and the orientation region and the non-orientation region are formed during the process of the electrode precursor passing through the magnetic field to obtain the electrode sheet; wherein, the magnetic field is provided by a magnetic component, the magnetic component includes N pole magnets and S pole magnets arranged alternately along a fourth direction, and the direction of movement of the electrode precursor when passing through the magnetic field is intersecting with or parallel to the fourth direction.

15. The method for preparing the electrode sheet according to claim 14, characterized in that, During the process of passing the electrode precursor through the magnetic field, the moving speed of the electrode precursor is 1m / min to 5m / min; And / or, during the process of passing the electrode precursor through the magnetic field, the distance between the electrode precursor and the magnetic component is 0.5cm to 5cm; And / or, during the process of passing the electrode precursor through the magnetic field, the magnetic components are respectively present on both opposite sides of the electrode precursor in the thickness direction; And / or, in the magnetic assembly, the distance between adjacent N-pole magnets and S-pole magnets is 0~0.5cm; And / or, the width of the N-pole magnet in the fourth direction is 1cm to 2cm; And / or, the width of the S-pole magnet in the fourth direction is 1cm to 2cm.

16. A battery, characterized in that, This includes the electrode sheet as described in any one of claims 1-13 or the electrode sheet prepared according to the method described in claim 14 or 15.

17. A battery pack, characterized in that, Includes the battery as described in claim 16.

18. An electrical appliance, characterized in that, Includes the battery of claim 16 or the battery pack of claim 17.

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