Pole piece, method of manufacturing the same, and use thereof

Abstract

The application provides a pole piece, a preparation method and application thereof. The pole piece comprises a current collector and an active material layer arranged on the surface of the current collector, wherein the active material layer comprises an active material; in a first direction, the porosity of the active material layer gradually increases, the particle size D50 of the active material in the active material layer gradually increases, and the electrolyte contact angle of the active material layer first increases and then decreases, wherein the first direction is perpendicular to the stacking direction. By using the active material layer with varying porosity, particle size D50 of the active material and electrolyte contact angle of the active material layer, the electrolyte wetting uniformity of the pole piece is improved, and the use performance of the pole piece and the battery is improved.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to electrode sheets, their preparation methods, and applications. Background Technology

[0002] Due to the orientation during use and the effects of gravity, the electrolyte tends to pool at one end of the battery, resulting in poor uniformity of electrolyte wetting of the electrodes and affecting battery performance. Therefore, further improvements to the battery structure are needed to enhance its performance. Summary of the Invention

[0003] In view of this, this application provides an electrode sheet, its preparation method and application. By adopting an active material layer with varying porosity, particle size D50, and electrolyte contact angle, the electrolyte wetting uniformity of the electrode sheet is improved, the interface state of the electrode sheet during use is improved, and thus the performance of the electrode sheet and the battery is enhanced.

[0004] In a first aspect, this application provides an electrode, including a current collector and an active material layer stacked on the surface of the current collector, the active material layer including an active material; along a first direction, the porosity of the active material layer gradually increases, the particle size D50 of the active material in the active material layer gradually increases, and the electrolyte contact angle of the active material layer first increases and then decreases, wherein the first direction is perpendicular to the stacking direction.

[0005] Optionally, along the first direction, the porosity of the active material layer increases from φ min Gradually increase to φ max 5% < φ min ≤20%, 30%<φ max ≤50%.

[0006] Optionally, along the first direction, the particle size D50 of the active material in the active material layer ranges from D50... min Gradually increase to D50 max 0.1μm≤D50 min <0.5μm, 1.5μm≤D50 max <2.5μm.

[0007] Optionally, along the first direction, the electrolyte contact angle of the active material layer ranges from θ min1 First increase to θ max Reduce to θ min2 0°<θ min1 ≤10°, 10°<θ max ≤20°, 0°<θ min2 ≤10°.

[0008] Optionally, along the first direction, the active material layer includes N active material portions, where N is an integer greater than or equal to 3; along the first direction, the absolute value of the difference in porosity between any two adjacent active material portions is... φ, 2%≤ φ < 25%.

[0009] Optionally, along the first direction, the active material layer includes N active material portions, where N is an integer greater than or equal to 3; along the first direction, the absolute value of the difference in particle size D50 of the active material in any two adjacent active material portions is... D50, 0.1μm≤ D50 < 1.4 μm.

[0010] Optionally, along the first direction, the active material layer includes N active material portions, where N is an integer greater than or equal to 3; along the first direction, the absolute value of the difference in electrolyte contact angle between any two adjacent active material portions is... θ, 2°≤ θ < 20°.

[0011] Optionally, along the first direction, the w of the active material portion satisfies: 2mm ≤ w < 400mm.

[0012] Optionally, along the first direction, the active material layer includes a first active material portion, a second active material portion, and a third active material portion arranged sequentially.

[0013] Optionally, the porosity φ1 of the first active material portion, the porosity φ2 of the second active material portion, and the porosity φ3 of the third active material portion satisfy the following: 5% < φ1 ≤ 20%, 20% < φ2 ≤ 30%, and 30% < φ3 ≤ 50%.

[0014] Optionally, the particle sizes D501 of the active material in the first active material section, D502 of the active material in the second active material section, and D503 of the active material in the third active material section satisfy the following: 0.1μm≤D501<0.5μm, 0.5μm≤D502<1.5μm, and 1.5μm≤D503<2.5μm.

[0015] Optionally, the electrolyte contact angle θ1 of the first active material portion, the electrolyte contact angle θ2 of the second active material portion, and the electrolyte contact angle θ3 of the third active material portion satisfy: 0°<θ1≤10°, 10°<θ2≤20°, 0°<θ3≤10°.

[0016] Optionally, the size of the active material layer along the first direction is 50mm-400mm.

[0017] Optionally, the electrode further includes a tab, which is disposed at one end of the current collector, and the first direction is the direction from the current collector to the tab.

[0018] Secondly, this application provides a method for preparing an electrode, comprising: coating an electrode slurry onto the surface of a current collector, drying and rolling to form an active material layer, wherein the electrode slurry comprises an active material, thereby obtaining an electrode, wherein along a first direction, the porosity of the active material layer gradually increases, the particle size D50 of the active material in the active material layer gradually increases, the electrolyte contact angle of the active material layer first increases and then decreases, and the first direction is perpendicular to the stacking direction of the active material layer and the current collector.

[0019] Optionally, the preparation method further includes: the electrode slurry includes N kinds of active material slurries, where N is an integer greater than or equal to 3; along the first direction, the N kinds of active material slurries are coated on the surface of the current collector, and after drying and rolling, N active material parts are formed to form the active material layer, thereby obtaining the electrode.

[0020] Thirdly, this application provides a battery comprising the electrode sheet described in the first aspect or the electrode sheet prepared by the preparation method described in the second aspect, and an electrolyte.

[0021] Fourthly, this application provides an electrical device including the battery described in the third aspect.

[0022] The porosity, particle size D50, and electrolyte contact angle variations of the active material layer in the electrode provided in this application can improve the electrolyte storage and wetting capabilities in different regions of the electrode. It can also generate capillary action within the active material layer, which is beneficial for electrolyte migration, thereby achieving uniform electrolyte wetting, which is conducive to the performance of the active material, improving the interface state of the electrode during use, and enhancing the electrical performance of the electrode and the battery. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. The specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0024] Figure 1 This is a schematic diagram of the structure of an electrode sheet provided in one embodiment of this application.

[0025] Figure 2 This is a schematic diagram of the structure of an electrode sheet provided for another embodiment of this application.

[0026] Figure 3 This is a schematic diagram of the structure of an electrode sheet provided in another embodiment of this application.

[0027] Figure 4 This is a schematic diagram of the structure of a battery provided in one embodiment of this application.

[0028] Label Explanation: Active material layer-10, first active material section-11, second active material section-12, third active material section-13, current collector-20, tab-30, electrode-100, battery-200. Detailed Implementation

[0029] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0030] Due to the orientation of the battery during use and the effects of gravity, the electrolyte tends to accumulate at one end of the battery, resulting in poor electrolyte wetting of the electrodes and affecting battery performance. For example, during use, due to gravity, the electrolyte may deposit at the bottom of the battery, leading to poor electrolyte wetting of the electrodes, especially at the top. Furthermore, the distribution of electrolyte additives can cause problems such as blackening at the top and lithium plating during cycling, further impacting the battery's cycle performance and hindering its use.

[0031] In view of this, this application provides an electrode. Please refer to... Figure 1 This is a schematic diagram of the structure of an electrode 100 provided in one embodiment of this application. The electrode 100 includes a current collector 20 and an active material layer 10 stacked on the surface of the current collector 20. The active material layer 10 includes an active material. Along a first direction, the porosity of the active material layer 10 gradually increases, the particle size D50 of the active material in the active material layer 10 gradually increases, and the electrolyte contact angle of the active material layer 10 first increases and then decreases. The first direction is perpendicular to the stacking direction. Figure 1The direction indicated by the middle arrow. The electrolyte contact angle of the active material layer first increases and then decreases, resulting in good wettability of the electrolyte in the areas near both ends of the active material layer, thus allowing for the absorption of more electrolyte. Simultaneously, along the first direction, the porosity and particle size of the active material layer gradually increase, enabling the storage of more electrolyte and enhancing the electrode's liquid absorption capacity. Furthermore, with the change in porosity and particle size, a capillary effect is generated in the active material layer, allowing the electrolyte to move to different areas of the active material layer, achieving excellent wetting effects. This is beneficial for the performance of the active material, improves the interface state during electrode use, and enhances the electrode's cycle performance.

[0032] In some embodiments of this application, the first direction is parallel to and opposite to the direction of gravity. That is, along the first direction, the active material layer has a top and a bottom, with the top of the active material layer having higher porosity, providing more storage space for the electrolyte. Due to the variations in porosity and particle size of the active material layer, a strong capillary effect is generated in the active material layer. Under the action of capillary force, the electrolyte has a stronger ability to climb to the top of the active material layer, improving the uniformity of wetting. At the same time, due to gravity, the electrolyte will accumulate at the bottom of the active material layer, and the electrolyte contact angle at the bottom of the active material layer is smaller, which can fully absorb the electrolyte. In addition, the transition region between the top and bottom can provide the capillary force required for the electrolyte to climb. Through the above combined effects, the electrolyte wetting effect of the electrode is improved, thereby significantly improving the cycle interface and increasing cycle life.

[0033] In this application, the active material layer includes a first surface and a second surface disposed opposite to each other along the thickness direction of the active material layer. The second surface is located between the current collector and the first surface. The thickness direction of the active material layer is the stacking direction. The first direction is parallel to the first surface and perpendicular to the stacking direction.

[0034] Along the first direction, the porosity of the active material layer gradually increases, which can be a gradient increase or a gradual increase (such as a linear increase or a non-linear increase). For example, along the first direction, the porosity of the active material layer gradually increases, which can achieve a change in porosity while reducing the difficulty and cost of preparing the active material layer, thus benefiting the use of the electrode. In some embodiments of this application, along the first direction, the porosity of the active material layer increases from φ... min Gradually increase to φ max 5% < φ min ≤20%, 30%<φ max ≤50%. The porosity variation range of the active material layer is suitable, which is beneficial for both electrolyte wetting and storage, as well as electrolyte migration within the active material layer, further improving the electrolyte wettability of the active material layer. For example, φ minIt can be, but is not limited to, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%, etc.; φ max Porosity can be, but is not limited to, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, or 50%. In this application, the porosity of the active material layer can be tested according to GB / T 24586-2009. In some embodiments, 8% ≤ φ min ≤17%, 35%≤φ max ≤45% is beneficial for further improving the performance of the electrode.

[0035] Along the first direction, the particle size D50 of the active material layer gradually increases, which can be a gradient increase or a gradual increase (such as a linear increase or a non-linear increase). For example, along the first direction, the particle size D50 of the active material layer gradually increases, which can achieve a change in particle size D50 while reducing the difficulty and cost of preparing the active material layer, thus benefiting the use of the electrode. In some embodiments of this application, along the first direction, the particle size D50 of the active material in the active material layer increases from D50... min Gradually increase to D50 max 0.1μm≤D50 min <0.5μm, 1.5μm≤D50 max <2.5μm. The particle size D50 of the active material in the active material layer has a suitable variation range, which is beneficial for both electrolyte wetting and storage, as well as electrolyte migration within the active material layer, further improving the electrolyte wettability of the active material layer. For example, D50... min It can be, but is not limited to, 0.1μm, 0.15μm, 0.2μm, 0.25μm, 0.3μm, 0.35μm, 0.4μm, 0.45μm, or 0.49μm, etc.; D50 max The particle size can be, but is not limited to, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, 2 μm, 2.1 μm, 2.2 μm, 2.3 μm, or 2.4 μm. The particle size D50 is the volume median diameter, and can be obtained by measuring the particle size D50 of the active material using a particle size analyzer, but is not limited to that measured by a particle size analyzer. In some embodiments, 0.15 μm ≤ D50. min ≤0.35μm, 1.6μm≤D50 max ≤2.3μm, which is beneficial to further improve the performance of the electrode.

[0036] Along the first direction, the electrolyte contact angle of the active material layer first increases and then decreases, which can be a gradient increase or a gradual increase, followed by a gradient decrease or a gradual decrease (e.g., linear decrease, non-linear decrease). For example, along the first direction, the electrolyte contact angle of the active material layer first increases and then decreases, which can achieve a change in the electrolyte contact angle while reducing the difficulty and cost of preparing the active material layer, thus benefiting the use of the electrode. In some embodiments of this application, along the first direction, the electrolyte contact angle of the active material layer changes from θ... min1 First increase to θ max Reduce to θ min2 0°<θ min1 ≤10°, 10°<θ max ≤20°, 0°<θ min2 ≤10°. θ min1 θ min2 The values ​​can be the same or different. A suitable range of electrolyte contact angle variation in the active material layer is beneficial for both electrolyte wetting and storage, as well as electrolyte migration within the active material layer, further enhancing the electrolyte wettability of the active material layer. For example, θ... min1 It can be, but is not limited to, 1°, 2°, 3°, 4°, 5°, 6°, 7°, 8°, 9°, or 10°, etc.; θ max It can be, but is not limited to, 11°, 12°, 13°, 14°, 15°, 16°, 17°, 18°, 19°, or 20°, etc.; θ min2 The angles can be, but are not limited to, 1°, 2°, 3°, 4°, 5°, 6°, 7°, 8°, 9°, or 10°. This application can detect the electrolyte contact angle of the active material layer by using a contact angle meter and adding electrolyte. The electrolyte contains a lithium salt and a solvent. The solvent is a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a 1:1:1 volume ratio. The lithium salt is lithium hexafluorophosphate, and the lithium salt concentration in the electrolyte is 1 mol / L. In some embodiments, 2° ≤ θ min1 ≤8°, 13°≤θ max ≤18°, 2°≤θ min2 ≤10° is beneficial for further improving the performance of the electrode.

[0037] In some embodiments of this application, along a first direction, the active material layer includes N active material portions, where N is an integer greater than or equal to 3. N can be selected based on various requirements such as electrode size, battery size, electrolyte wetting conditions, and battery energy density. That is, the active material layer may include a first active material portion, a second active material portion, ..., an Nth active material portion; wherein the porosities of the first active material portion, the second active material portion, ..., the Nth active material portion are φ1, φ2, ..., φ..., respectively. N The particle sizes D50 are D501, D502, ..., D50, respectively. N The electrolyte contact angles are θ1, θ2, ..., θ... N For example, N can be, but is not limited to, 3, 4, 5, 6, 7, 8, 9, or 10. In some embodiments, N can be selected from 3, 4, 5, or 6, which can generate a strong capillary effect within the active material layer, further facilitating electrolyte migration and achieving a more uniform wetting effect. It also benefits electrode preparation, reducing preparation costs and thus leading to electrodes with excellent overall performance. For example, N can be 3, which can give the electrode excellent electrolyte wetting effects while reducing preparation costs and difficulty, thus facilitating the use of the electrode.

[0038] In some embodiments of this application, along the first direction, the absolute value of the difference in porosity between any two adjacent active material portions is... φ, 2%≤ A φ < 25% ratio facilitates the generation of suitable capillary forces between adjacent active material portions, further aiding in electrolyte migration and wetting, improving the electrolyte wetting uniformity of the electrode, and thus enhancing the electrode's electrical performance. For example, φ can be, but is not limited to, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, or 24%, etc. In some embodiments, φ can satisfy: 5%≤ A value of φ≤15% is beneficial for further improving the performance of the electrode.

[0039] In some embodiments of this application, along the first direction, the absolute value of the difference in particle size D50 of the active material in any two adjacent active material portions is D50, 0.1μm≤ A D50 < 1.4 μm facilitates the generation of suitable capillary forces between adjacent active material sections, further aiding in electrolyte migration and wetting, improving the electrolyte wetting uniformity of the electrode, and thus enhancing the electrode's electrical performance. For example, D50 can be, but is not limited to, 0.1μm, 0.2μm, 0.3μm, 0.4μm, 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, 1.1μm, 1.2μm, or 1.3μm. In some embodiments, D50 can meet the following requirement: 0.5μm≤ D50≤1.2μm is beneficial for further improving the performance of the electrode.

[0040] In some embodiments of this application, along the first direction, the absolute value of the difference in electrolyte contact angle between any two adjacent active material portions is... θ, 2°≤ A θ < 20° angle is beneficial for creating a suitable wettability difference between adjacent active material sections, which is advantageous for both electrolyte storage and wetting, as well as electrolyte migration, resulting in an electrode with superior performance. For example, θ can be, but is not limited to, 2°, 3°, 4°, 5°, 6°, 7°, 8°, 9°, 10°, 11°, 12°, 13°, 14°, 15°, 16°, 17°, 18°, or 19°, etc. In some embodiments, θ can satisfy: 5°≤ θ≤15° is beneficial for further improving the performance of the electrode.

[0041] Please see Figure 2 This is a schematic diagram of the structure of an electrode sheet provided in another embodiment of this application, wherein, along a first direction, the active material layer includes a first active material portion 11, a second active material portion 12, and a third active material portion 13 arranged sequentially. The first direction is... Figure 2 The direction indicated by the middle arrow.

[0042] In some embodiments of this application, the porosity φ1 of the first active material portion, the porosity φ2 of the second active material portion, and the porosity φ3 of the third active material portion satisfy the following: 5% < φ1 ≤ 20%, 20% < φ2 ≤ 30%, and 30% < φ3 ≤ 50%. The porosity ranges of the first, second, and third active material portions are suitable, and the porosity differences between adjacent active material portions are appropriate. This is beneficial for electrolyte storage and wetting, as well as for electrolyte migration between different active material portions, further improving the uniformity of electrolyte wetting of the active material layer. For example, φ1 can be, but is not limited to, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%; φ2 can be, but is not limited to, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, or 30%; φ3 can be, but is not limited to, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, or 50%.

[0043] In some embodiments of this application, the particle sizes D501 of the active material in the first active material section, D502 of the active material in the second active material section, and D503 of the active material in the third active material section satisfy the following: 0.1 μm ≤ D501 < 0.5 μm, 0.5 μm ≤ D502 < 1.5 μm, and 1.5 μm ≤ D503 < 2.5 μm. The particle size D50 ranges of the first, second, and third active material sections are suitable, and the difference in particle size D50 between adjacent active material sections is appropriate. This is beneficial for electrolyte storage and wetting, as well as for electrolyte migration between different active material sections, further improving the uniformity of electrolyte wetting of the active material layer. For example, D501 can be, but is not limited to, 0.1μm, 0.15μm, 0.2μm, 0.25μm, 0.3μm, 0.35μm, 0.4μm, 0.45μm, or 0.49μm; D502 can be, but is not limited to, 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, 1.2μm, 1.3μm, or 1.4μm; D503 can be, but is not limited to, 1.5μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm, 2μm, 2.1μm, 2.2μm, 2.3μm, or 2.4μm.

[0044] In some embodiments of this application, the electrolyte contact angles θ1 of the first active material portion, θ2 of the second active material portion, and θ3 of the third active material portion satisfy the following conditions: 0° < θ1 ≤ 10°, 10° < θ2 ≤ 20°, and 0° < θ3 ≤ 10°. The electrolyte contact angle ranges of the first, second, and third active material portions are suitable, and the differences in electrolyte contact angles between adjacent active material portions are appropriate. This is beneficial for electrolyte storage and wetting, as well as for electrolyte migration between different active material portions, further improving the uniformity of electrolyte wetting in the active material layer. For example, θ1 can be, but is not limited to, 1°, 2°, 3°, 4°, 5°, 6°, 7°, 8°, 9°, or 10°; θ2 can be, but is not limited to, 11°, 12°, 13°, 14°, 15°, 16°, 17°, 18°, 19°, or 20°; θ3 can be, but is not limited to, 1°, 2°, 3°, 4°, 5°, 6°, 7°, 8°, 9°, or 10°.

[0045] In some embodiments of this application, the dimension w of the active material portion along the first direction satisfies: 2mm ≤ w < 400mm. For example, Figure 2 The diagram shows the dimension w of the first active material portion in a first direction. Exemplarily, w can be, but is not limited to, 2 mm, 5 mm, 10 mm, 15 mm, 20 mm, 22 mm, 24 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, 120 mm, 150 mm, 170 mm, 200 mm, 250 mm, 300 mm, 330 mm, 380 mm, or 390 mm. In some embodiments, the dimension w of the active material portion can be 2 mm to 390 mm.

[0046] In some embodiments of this application, the size of the active material layer along the first direction is 50mm-400mm. For example, Figure 2 The diagram shows the dimension h of the active material layer in the first direction, i.e., h is 50mm-400mm. For example, h can be, but is not limited to, 50mm, 60mm, 70mm, 80mm, 90mm, 100mm, 120mm, 150mm, 170mm, 200mm, 220mm, 250mm, 275mm, 300mm, 350mm, 380mm, or 390mm, etc.

[0047] In some embodiments of this application, the mass content of the active material in the active material layer is greater than or equal to 85%, thereby ensuring the electrical performance of the electrode. Exemplarily, the mass content of the active material in the active material layer may be, but is not limited to, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%. The appropriate active material can be selected according to the application scenario of the electrode; for example, when the electrode is used as a negative electrode, a negative electrode active material is selected; when the electrode is used as a positive electrode, a positive electrode active material is selected. The negative electrode active material may be, but is not limited to, selected from at least one of carbon materials (such as graphite, soft carbon, hard carbon, etc.), silicon-based materials (such as silicon-oxygen materials, silicon-carbon materials, etc.), and metallic materials (such as lithium, etc.). The positive electrode active material includes at least one of the following: layered oxides (such as lithium cobalt oxide, ternary materials, lithium-rich manganese-based materials, etc.), polyanionic materials (such as lithium iron phosphate, lithium iron manganese phosphate, etc.), and spinel oxides (such as lithium manganese oxide, lithium nickel manganese oxide, etc.). The active material layer includes N active material sections, and the mass content of active material in each active material section is greater than or equal to 85%. The mass content of active material in different active material sections can be the same or different.

[0048] In some embodiments of this application, the surface of the active material has polar groups. These polar groups can alter the electrolyte contact angle of the active material layer. The active material layer comprises N active material portions, and the content of polar groups on the active material in different active material portions can be the same or different. In some embodiments, the content of polar groups on the active material in different active material portions is different, thereby resulting in different electrolyte contact angles between different active material portions, achieving a change in the electrolyte contact angle of the active material layer that first increases and then decreases. In some embodiments, the active material comprises an active material core and a coating layer covering the active material core, the coating layer carrying polar groups. Exemplarily, the coating layer may be, but is not limited to, a carbon coating layer; the polar groups may be, but are not limited to, polar groups such as -COOH, C=O, etc.

[0049] In some embodiments of this application, the active material layer may further include at least one of a conductive agent and a binder. Adding a conductive agent can improve the conductivity of the electrode, while adding a binder can improve the adhesion stability of the active material layer on the current collector surface. In some embodiments, the mass content of the conductive agent in the active material layer can be 0.1%-10%. For example, the mass content of the conductive agent in the active material layer can be, but is not limited to, 0.1%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%. The active material layer includes N active material portions, and the mass content of the conductive agent in each active material portion can be 0.1%-10%. The mass content of the conductive agent in different active material portions can be the same or different. The conductive agent may include, but is not limited to, at least one of carbon nanowires, carbon nanotubes, carbon black, acetylene black, graphite, and graphene. In some embodiments, the mass content of the binder in the active material layer can be 0.5%-5%. For example, the mass content of the conductive agent in the active material layer can be, but is not limited to, 0.5%, 1%, 2%, 3%, 4%, or 5%. The active material layer comprises N active material portions. The mass content of the binder in each active material portion can be 0.5%-5%, and the mass content of the binder in different active material portions can be the same or different. The binder may include, but is not limited to, at least one of polythiophene, polypyrrole, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polystyrene, styrene-butadiene rubber, polybutadiene, polyvinylpyrrolidone, carboxypropyl cellulose, sodium carboxymethyl cellulose, and styrene-butadiene rubber.

[0050] The material of the current collector in this application can be selected as needed. In some embodiments of this application, the material of the current collector is selected from metals or alloys. Metals include copper, titanium, aluminum, platinum, iridium, ruthenium, nickel, tungsten, tantalum, gold, or silver; alloys include stainless steel, or alloys containing at least one element selected from copper, titanium, aluminum, platinum, iridium, ruthenium, nickel, tungsten, tantalum, gold, and silver. For example, when the electrode is used as a positive electrode, the material of the current collector can be selected from aluminum or aluminum alloys; when the electrode is used as a negative electrode, the material of the current collector can be selected from copper or copper alloys. The form of the current collector can be, but is not limited to, foil, foam mesh, etc.

[0051] Please see Figure 3 This is a schematic diagram of the structure of an electrode sheet provided in another embodiment of this application, wherein the electrode sheet 100 further includes an electrode tab 30, which is disposed at one end of the current collector 20, and the first direction is the direction from the current collector 20 to the electrode tab 30.

[0052] This application provides a method for preparing an electrode, comprising: coating an electrode slurry onto the surface of a current collector, drying and rolling to form an active material layer, wherein the electrode slurry includes an active material, and an electrode is obtained, wherein along a first direction, the porosity of the active material layer gradually increases, the particle size D50 of the active material in the active material layer gradually increases, the electrolyte contact angle of the active material layer first increases and then decreases, and the first direction is perpendicular to the stacking direction of the active material layer and the current collector.

[0053] In some embodiments of this application, the preparation method further includes: the electrode slurry comprising N types of active material slurries, where N is an integer greater than or equal to 3; the N types of active material slurries are coated onto the surface of the current collector along a first direction, and after drying and rolling, N active material portions are formed, thus forming an active material layer and obtaining the electrode. By coating different active material slurries, active material portions with different properties can be obtained, thereby achieving variations in the porosity, particle size D50, and electrolyte contact angle of the active material layer.

[0054] In some embodiments of this application, the electrode slurry includes an active material. In N types of active material slurries, at least one parameter differs in the content of polar groups on the surface of the active material, the mass content of the active material, the particle size distribution of the active material, and the particle size D50 of the active material, thereby causing variations in the porosity, particle size D50, and contact angle of the active material layer in the first direction.

[0055] In some embodiments of this application, the active material includes an active material core and a coating layer covering the active material core, the coating layer carrying polar groups. In some embodiments, raw materials containing each element of the active material core and a carbon source can be blended, and then sintered to obtain the active material core and the coating layer covering the active material core; at this time, the coating layer is a carbon coating layer, and its surface has a variety of polar groups. In some embodiments, a lithium source (such as lithium carbonate), an iron source (such as ferrous oxalate), a phosphorus source (such as ammonium dihydrogen phosphate), and a carbon source (such as glucose) can be blended in a ball mill, and then dried and sintered to obtain a carbon-coated lithium iron phosphate material.

[0056] In some embodiments of this application, the mass ratio of active material to solids in the electrode slurry is greater than or equal to 85%, thereby ensuring the electrical performance of the formed electrode. Exemplarily, the mass ratio of active material to solids in the electrode slurry may be, but is not limited to, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%, etc.

[0057] In some embodiments of this application, the particle size D50 of the active material in the electrode slurry is greater than or equal to 0.1 μm and less than 2.5 μm. A suitable particle size of the active material is beneficial for improving the energy density of the electrode. Exemplarily, the particle size D50 of the active material can be, but is not limited to, 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, 2 μm, 2.1 μm, 2.2 μm, 2.3 μm, or 2.4 μm.

[0058] In some embodiments of this application, the electrode slurry further includes a conductive agent, and the mass ratio of the conductive agent to the solids in the electrode slurry is 0.1%-10%. In some embodiments, the mass ratio of the conductive agent to the solids in the electrode slurry in the active material portion is 0.1%-10%.

[0059] In some embodiments of this application, the electrode slurry further includes a binder, and the mass ratio of the binder to the solids in the electrode slurry is 0.5%-5%. In some embodiments, the mass ratio of the binder to the solids in the active material portion slurry is 0.5%-5%.

[0060] In some embodiments of this application, the electrode slurry further includes an electrode solvent. The electrode solvent may include at least one of ethanol, toluene, xylene, ethyl acetate, ethyl propionate, butyl butyrate, N-methylpyrrolidone, acetone, and water.

[0061] In this application, N types of active material slurries can be coated, dried, and rolled together to obtain an active material layer; alternatively, the N types of active material slurries can be coated, dried, and rolled separately to obtain a first active material layer, a second active material layer, ..., an Nth active material layer; or the N types of active material slurries can be coated and dried separately, then rolled together to obtain an active material layer. The specific process method can be selected according to needs.

[0062] This application provides a battery, including the electrode sheet as described in any of the above embodiments, and an electrolyte. The electrode sheet provided by this application has excellent electrolyte wetting uniformity, ensuring the battery's cycle performance, improving the battery's electrical performance, and facilitating its use. Depending on the application field, the battery may be, but is not limited to, a consumer battery, a power battery, and an energy storage battery; depending on the material system, the battery may be, but is not limited to, a lithium-ion battery (such as a ternary lithium battery, a lithium iron phosphate battery, etc.). Please refer to [link to relevant documentation]. Figure 4 This is a schematic diagram of the structure of a battery provided in one embodiment of this application, wherein the battery 200 includes the electrode sheets in any of the above embodiments.

[0063] In this application, the battery may also include an electrolyte, with at least a portion of the electrode sheets immersed in the electrolyte. In some embodiments of this application, the electrolyte includes an electrolyte and an electrolyte solvent. The electrolyte includes a lithium salt, which includes at least one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium difluorooxalate borate, lithium bis(oxalate borate), lithium bis(trifluoromethanesulfonyl)imide, and lithium tetrafluoroborate. The electrolyte solvent includes at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate. In some embodiments, the electrolyte may also include an electrolyte additive, which includes at least one of fluoroethylene carbonate, ethylene sulfate, and vinylene carbonate. The above-mentioned electrolyte additives are beneficial for reducing the impedance of the interfacial film, improving ion transport efficiency, and optimizing the battery's electrical performance.

[0064] In this application, the battery may also have a separator disposed between the positive electrode and the negative electrode. This application does not impose any particular limitation on the separator; any material in the art that can be used as a battery separator may be employed, but is not limited to.

[0065] Batteries can also have encapsulation structures, such as aluminum shells or aluminum-plastic films.

[0066] This application provides an electrical device, including the battery in any of the above embodiments. The battery in the electrical device provided by this application has excellent performance, which is beneficial to the use of the electrical device. Specifically, the electrical device may refer to vehicles, electronic devices (such as mobile phones, computers, cameras, watches, bracelets, etc.), energy storage systems, etc.

[0067] The effects of the technical solution in this application will be further illustrated below with specific examples.

[0068] Experimental group 1 Comparative Example 1-1 Lithium iron phosphate (with a carbon coating layer covering the lithium iron phosphate core), polyvinylidene fluoride, and conductive carbon black SP are mixed in a mass ratio of 97:2:1 and N-methylpyrrolidone (NMP) is added to form the first active material slurry.

[0069] Lithium iron phosphate (with a carbon coating layer covering the lithium iron phosphate core), polyvinylidene fluoride, and conductive carbon black SP are mixed in a mass ratio of 97:2:1 and NMP is added to form the second active material slurry.

[0070] Lithium iron phosphate (with a carbon-coated lithium iron phosphate core), polyvinylidene fluoride, and conductive carbon black SP were mixed at a mass ratio of 97:2:1 and NMP was added to form the third active material slurry. The first, second, and third active material slurries differ in the content of polar groups on the surface of the carbon coating, the lithium iron phosphate particle size D50, and the lithium iron phosphate particle size distribution.

[0071] The first active material slurry is coated onto the surface of an aluminum foil, and after drying and rolling, the first active material portion is formed. The second active material slurry is coated onto the surface of an aluminum foil, and after drying and rolling, the second active material portion is formed. The third active material slurry is coated onto the surface of an aluminum foil, and after drying and rolling, the third active material portion is formed. The first active material portion, the second active material portion, and the third active material portion are arranged along a first direction to form an active material layer, thereby obtaining a positive electrode sheet.

[0072] Comparative Examples 1-2 to 1-7 Positive electrode sheets were prepared using the same method as Comparative Example 1-1, but the content of polar groups on the surface of the carbon coating layer in the active material slurry was different, as were the particle size D50 and particle size distribution of lithium iron phosphate.

[0073] The particle size D50 of lithium iron phosphate in the above comparative example was detected using a particle size analyzer. The results are shown in Table 1 under "Particle Size". The unit is μm and is not shown in Table 1.

[0074] The porosity of the active material obtained in the above comparative example was tested according to GB / T 24586-2009. The electrode sheets were punched into small round discs with a diameter of 10 mm using a punching machine. The discs had neat ends, and the number of discs was ≥40. The thickness of the small discs was measured with a micrometer, and the average value was taken. The small discs were placed in the chamber of the testing instrument, and the testing software was opened for testing. A test report was output to confirm the porosity data. Parallel sample tests were added, and the average value was taken as the porosity of the active material. The results are shown in Table 1 under "Porosity" (unit: %), and are not shown in Table 1.

[0075] The contact angle of the active material obtained in the above comparative example was measured by adding electrolyte using a contact angle meter. The electrolyte contained lithium salt and solvent. The solvent was a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 1:1:1. The lithium salt was lithium hexafluorophosphate, and the concentration of lithium salt in the electrolyte was 1 mol / L. The results are shown in "Contact Angle" in Table 1, with the unit being °. (The results are not shown in Table 1.)

[0076] Table 1. Performance test results of the positive electrode sheet in Experimental Group 1

[0077] Artificial graphite, conductive carbon black SP, carboxymethyl cellulose, and styrene-butadiene rubber were mixed evenly in a mass ratio of 96:1:1:1 and dispersed in water to obtain a negative electrode slurry. The negative electrode slurry was coated on copper foil and dried in a vacuum environment at 100°C to obtain a negative electrode sheet.

[0078] Dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate are mixed in a mass ratio of 1:1:1 to form an electrolyte solvent. The electrolyte solvent is then mixed with lithium hexafluorophosphate and vinylene carbonate to form an electrolyte. The concentration of lithium hexafluorophosphate in the electrolyte is 1 mol / L, and the mass content of vinylene carbonate in the electrolyte is 3.5%.

[0079] The positive electrode sheet, polyethylene separator, and negative electrode sheet prepared in the above comparative example are stacked in sequence, with the separator positioned between the positive and negative electrode sheets, and then wound to obtain a bare cell. Multiple bare cells are placed in outer packaging shells, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and volume determination processes, a battery is prepared.

[0080] The battery was left to stand at 25℃ for 30 minutes, then charged at 1C constant current and constant voltage to 3.65V, with a cutoff current of 0.05C. After standing for 30 minutes, it was discharged at 1C to 2.5V. This charge-discharge cycle was repeated 2000 times. The capacity retention rate and the interface state at the end of battery life (EOL) were recorded. The capacity retention rate (%) after 2000 cycles = (capacity of the 2000th cycle / initial capacity) × 100%. The interface state included the condition of black spots on the top (classified by severity as no black spots on the top, slight black spots on the top, moderate black spots on the top, and severe black spots on the top), black spots on the bottom (classified by severity as no black spots on the bottom, slight black spots on the bottom, moderate black spots on the bottom, and severe black spots on the bottom), and lithium plating (classified by severity as no lithium plating, slight lithium plating, moderate lithium plating, and severe lithium plating). When there were no black spots on the top and bottom and no lithium plating, the interface was considered "good". The results are shown in Table 2.

[0081] Table 2 Battery performance test results for Experimental Group 1

[0082] Comparative Examples 1-1 to 1-4 show that: when the particle size is too small and the porosity is too low (e.g., 0.1 μm, 5% porosity), severe black spots are found at the bottom and top of the electrode, along with severe lithium plating. The main reason is insufficient electrolyte retention at the bottom of the positive electrode, which affects the lithium ion insertion / extraction at the bottom, causing the bottom cycling black spot problem. Due to the weakened electrolyte retention at the bottom of the electrode, the electrolyte at the top is relatively sufficient, which alleviates the top black spot and lithium plating problem. When the particle size is too large and the porosity is too high (e.g., 0.5 μm, 20% porosity), the bottom black spot problem is alleviated, but the top black spot and lithium plating problem still exist. The main reason is insufficient electrolyte retention at the bottom of the positive electrode, which affects the lithium ion insertion / extraction at the bottom, causing the bottom cycling black spot problem.

[0083] Comparative Examples 1-5 to 1-7 show that: when the contact angle between the cathode material and the electrolyte is too small, such as 2°, the top black spots and lithium plating are severe, while the bottom interface is good. This is mainly because the cathode sheet has a strong liquid retention capacity at the bottom, ensuring sufficient electrolyte at the bottom. However, due to the small contact angle and excessive liquid retention capacity, the capillary force for the electrolyte to climb upwards at the bottom is reduced, thus reducing the amount of electrolyte retained at the top and worsening the circulation interface at the top. When the contact angle between the cathode material and the electrolyte is too large, such as 10°, the top black spots and lithium plating are somewhat alleviated, and the black spots at the bottom interface become less severe. This is mainly because the large contact angle results in a smaller liquid retention capacity, which to some extent enhances the capillary force for the electrolyte to climb upwards at the bottom, thereby increasing the amount of electrolyte retained at the top and alleviating the black spots and lithium plating problems at the circulation interface at the top. However, due to the large contact angle and relatively weak liquid retention capacity, the bottom black spot phenomenon still exists.

[0084] Experimental group 2 The positive electrode sheet was prepared using the same method as Comparative Example 1-1 in Experimental Group 1, except that the content of polar groups on the surface of the carbon coating layer in the active material slurry, the D50 particle size of lithium iron phosphate, and the particle size distribution of lithium iron phosphate differed. The particle size D50 of lithium iron phosphate in the active material was measured using the same method as described above, and the results are shown in Table 3 under "Particle Size" (in μm, not shown in Table 3). The porosity of the active material was measured using the same method as described above, and the results are shown in Table 3 under "Porosity" (in %) (not shown in Table 3). The electrolyte contact angle of the active material was measured using the same method as described above, and the results are shown in Table 3 under "Contact Angle" (in °, not shown in Table 3).

[0085] Table 3 Performance test results of the positive electrode sheet in Experimental Group 2

[0086] Batteries were manufactured using the same method described above, and the capacity retention rate and EOL full charge disassembly interface status were tested. The results are shown in Table 4.

[0087] Table 4 Battery performance test results for Experimental Group 2

[0088] Comparative Examples 2-1 to 2-3 show that: When the particle size is too small and the porosity is too low (e.g., 0.5 μm, 20% porosity), black spots and lithium plating still exist at the top of the electrode. The main reason is insufficient porosity in the second region, resulting in insufficient capillary action and affecting the electrolyte's ascent to the top. Conversely, when the particle size is too large and the porosity is too high (e.g., 1.5 μm, 30% porosity), the black spots and lithium plating at the top are exacerbated. The main reason is that the porosity in the second region of the positive electrode is too large, failing to form a good gradient effect with the first region, thus reducing the capillary force for the electrolyte to ascend to the top.

[0089] Comparative Examples 2-4 to 2-6 show that: When the contact angle between the cathode material and the electrolyte is too small (e.g., 10°), black spots and slight lithium plating appear at the top, but the interface shows further improvement. This is mainly because the first and second regions of the cathode form a good pore gradient, giving the electrolyte strong capillary force, making it easier for the electrolyte to climb to the top of the electrode, thus alleviating top lithium plating. However, due to the small contact angle and excessively strong liquid retention capacity, the capillary force for the electrolyte to climb upwards is weakened, failing to further improve the top circulation interface. When the contact angle between the cathode material and the electrolyte is too large (e.g., 19°), slight black spots appear at the top, but the top interface shows further improvement. This is mainly because the contact angle of the second region is too large, resulting in a smaller liquid retention capacity, which further enhances the synergistic effect between the first and second regions, increasing the capillary force of the electrolyte, further increasing the electrolyte retention at the top, and improving the top circulation interface.

[0090] Experimental group 3 The positive electrode sheet was prepared using the same method as Comparative Example 1-1 in Experimental Group 1, except that the content of polar groups on the surface of the carbon coating layer in the active material slurry, the D50 particle size of lithium iron phosphate, and the particle size distribution of lithium iron phosphate varied. The particle size D50 of lithium iron phosphate in the active material was measured using the same method as described above, and the results are shown in Table 5 under "Particle Size" (in μm, not shown in Table 5). The porosity of the active material was measured using the same method as described above, and the results are shown in Table 5 under "Porosity" (in %) (not shown in Table 5). The electrolyte contact angle of the active material was measured using the same method as described above, and the results are shown in Table 5 under "Contact Angle" (in °, not shown in Table 5).

[0091] Table 5. Performance test results of the positive electrode sheet in Experimental Group 3

[0092] Batteries were manufactured using the same method described above, and the capacity retention rate and EOL full charge disassembly interface status were tested. The results are shown in Table 6.

[0093] Table 6 Battery performance test results for Experiment Group 3

[0094] Comparative Examples 3-1 and 3-2 show that: When particle size is too small and porosity is too low (e.g., 1.5 μm, 30% porosity), a small number of black spots still appear at the top of the electrode, showing no significant improvement compared to Comparative Examples 2-5. The main reason is insufficient porosity in the third region, resulting in insufficient capillary action and an inability to effectively absorb more electrolyte that rises from the bottom due to respiration and capillary forces. When particle size is too large and porosity is too high (e.g., 2.5 μm, 50% porosity), black spots appear at the top, indicating a deterioration compared to Comparative Examples 2-5. The main reason is the large porosity in the third region of the positive electrode, which fails to effectively absorb the electrolyte rising from the bottom, thus worsening the circulation interface.

[0095] As can be seen from Examples 3-1 to 3-7, the porosity of the active material layer gradually increases in the first direction, the particle size D50 of the active material in the active material layer gradually increases, and the electrolyte contact angle of the active material layer first increases and then decreases, improving the wetting effect of the electrolyte on the electrode, resulting in a good interface state, which is beneficial to the use of the battery. Compared with Examples 3-4 to 3-7, the porosity, particle size D50 of the active material in the active material section, the electrolyte contact angle of the active material section, and the range of porosity difference, particle size D50 difference, and electrolyte contact angle difference between adjacent active material sections are more suitable in Examples 3-1 to 3-3, which is more conducive to the rapid and uniform wetting of the electrolyte, further improving the performance of the electrode and the battery.

[0096] The above description is an exemplary embodiment of this application, but it should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this application, and these improvements and modifications are also considered to be within the scope of protection of this application.

Claims

1. An electrode sheet, characterized in that, The device includes a current collector and an active material layer stacked on the surface of the current collector. The active material layer includes an active material. Along a first direction, the porosity of the active material layer gradually increases, the particle size D50 of the active material in the active material layer gradually increases, and the electrolyte contact angle of the active material layer first increases and then decreases. The first direction is perpendicular to the stacking direction.

2. The electrode sheet as described in claim 1, characterized in that, Along the first direction, the porosity of the active material layer changes from φ min Gradually increase to φ max 5% < φ min ≤20%, 30%<φ max ≤50%; and / or, Along the first direction, the particle size D50 of the active material in the active material layer ranges from D50... min Gradually increase to D50 max 0.1μm≤D50 min <0.5μm, 1.5μm≤D50 max <2.5μm; and / or, Along the first direction, the electrolyte contact angle of the active material layer ranges from θ min1 First increase to θ max Reduce to θ min2 0°<θ min1 ≤10°, 10°<θ max ≤20°, 0°<θ min2 ≤10°.

3. The electrode sheet as described in claim 1 or 2, characterized in that, Along the first direction, the active material layer includes N active material portions, where N is an integer greater than or equal to 3; Along the first direction, the absolute value of the difference in porosity between any two adjacent active material portions is φ, 2%≤ φ < 25%; and / or, Along the first direction, the absolute value of the difference in particle size D50 of the active material in any two adjacent active material portions is D50, 0.1μm≤ D50 < 1.4 μm; And / or, Along the first direction, the absolute value of the difference in electrolyte contact angle between any two adjacent active material portions is θ, 2°≤ θ < 20°.

4. The electrode sheet as described in claim 3, characterized in that, Along the first direction, the size w of the active material portion satisfies: 2mm ≤ w < 400mm.

5. The electrode sheet according to any one of claims 1-4, characterized in that, Along the first direction, the active material layer includes a first active material portion, a second active material portion, and a third active material portion arranged sequentially; The porosity φ1 of the first active material portion, the porosity φ2 of the second active material portion, and the porosity φ3 of the third active material portion satisfy: 5% < φ1 ≤ 20%, 20% < φ2 ≤ 30%, 30% < φ3 ≤ 50%; and / or, The particle sizes D501 of the active material in the first active material section, D502 of the active material in the second active material section, and D503 of the active material in the third active material section satisfy: 0.1 μm ≤ D501 < 0.5 μm, 0.5 μm ≤ D502 < 1.5 μm, 1.5 μm ≤ D503 < 2.5 μm; and / or, The electrolyte contact angle θ1 of the first active material part, the electrolyte contact angle θ2 of the second active material part, and the electrolyte contact angle θ3 of the third active material part satisfy: 0°<θ1≤10°, 10°<θ2≤20°, 0°<θ3≤10°.

6. The electrode sheet according to any one of claims 1-5, characterized in that, Along the first direction, the size of the active material layer is 50mm-400mm.

7. The electrode sheet according to any one of claims 1-6, characterized in that, The electrode also includes a tab, which is disposed at one end of the current collector, and the first direction is the direction from the current collector to the tab.

8. A method for preparing an electrode sheet, characterized in that, include: An electrode slurry is coated onto the surface of a current collector, and after drying and rolling, an active material layer is formed. The electrode slurry includes an active material to obtain an electrode. In the first direction, the porosity of the active material layer gradually increases, the particle size D50 of the active material in the active material layer gradually increases, and the electrolyte contact angle of the active material layer first increases and then decreases. The first direction is perpendicular to the stacking direction of the active material layer and the current collector.

9. The preparation method according to claim 8, characterized in that, The preparation method further includes: The electrode slurry includes N types of active material slurries, where N is an integer greater than or equal to 3; Along the first direction, the N kinds of active material slurry are coated on the surface of the current collector, and after drying and rolling, N active material parts are formed to form the active material layer, thus obtaining the electrode.

10. A battery, characterized in that, Includes the electrode sheet according to any one of claims 1-7 or the electrode sheet prepared by the preparation method according to any one of claims 8-9, and the electrolyte.

11. An electrical appliance, characterized in that, Includes the battery as described in claim 10.

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