A pole piece and a lithium-ion secondary battery including the same

Abstract

The present invention provides a pole piece and a lithium-ion secondary battery including the pole piece. The pole piece includes a current collector, a metal mesh, and an active material layer. The active material layer is provided on one or both surfaces of the current collector, and the metal mesh is embedded in the active material layer and connected to the current collector. The pole piece of the present invention forms a multi-current collector in a practical sense, which is beneficial to shortening the migration path of lithium ions, reducing the polarization of the pole piece, and improving the cycle performance of the lithium-ion secondary battery. When applied to the negative electrode piece, it is beneficial to improve the charging ability of the negative electrode piece. When applied to the positive electrode piece, it is beneficial to reduce the impedance of the positive electrode piece and improve the rate performance of the lithium-ion secondary battery. Due to the presence of the multi-current collector, the active material loading can be greatly increased, which is beneficial to improving the energy density of the lithium-ion secondary battery.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion secondary batteries, and particularly relates to an electrode sheet and a lithium-ion secondary battery including the electrode sheet. Background Art

[0002] Lithium-ion secondary batteries are widely used due to their advantages such as high specific energy, low self-discharge, long cycle life, and no pollution to the environment. Their application products cover all aspects of people's lives, such as digital products like mobile phones, laptops, and Bluetooth headsets, as well as power fields such as power tools, electric vehicles, and energy storage.

[0003] With the lightening and miniaturization of electronic products and people's eagerness for high power conversion efficiency, the demand for the energy density of lithium-ion secondary batteries is becoming increasingly strong. To improve the energy density of lithium-ion secondary batteries, on the one hand, the compaction density of the electrode sheet is getting higher and higher, resulting in a sharp deterioration of the charging ability of the electrode sheet, which is not conducive to fast charging, and the pores of the electrode sheet are reduced, and the electrolyte is insufficient, leading to a decrease in the cycle life of the battery; on the other hand, the areal density of the active material of the electrode sheet is getting higher and higher, and the polarization of the positive and negative electrode sheets increases, which is not conducive to the rate performance and cycle performance of the battery. Therefore, how to balance the charging performance and rate performance of the battery under high energy density has become the focus of people's research. Summary of the Invention

[0004] In order to improve the deficiencies of the prior art, the purpose of the present invention is to provide an electrode sheet and a lithium-ion secondary battery including the electrode sheet. The electrode sheet includes a current collector, a metal mesh, and an active material layer; the active material layer is provided on one or both surfaces of the current collector, and the metal mesh is embedded in the active material layer and connected to the current collector. The use of the electrode sheet can reduce polarization, improve the kinetic performance of the electrode sheet at high areal density, thereby improving the volume energy density of the battery, and at the same time can reduce the impedance of the electrode sheet and improve the rate performance of the lithium-ion secondary battery.

[0005] To achieve the above purpose, the technical solutions adopted by the present invention are as follows:

[0006] An electrode sheet, the electrode sheet includes a current collector, a metal mesh, and an active material layer; the active material layer is provided on one or both surfaces of the current collector, and the metal mesh is embedded in the active material layer and connected to the current collector.

[0007] According to the present invention, the metal mesh includes a first side and a second side adjacent to the first side.

[0008] According to the present invention, the shape of the metal mesh is, for example, a rectangular structure, where the first side can be the long side or the short side of the rectangle. Taking the metal mesh with a rectangular structure as an example, the area of the metal mesh is the length of the first side multiplied by the length of the second side adjacent to the first side.

[0009] According to the present invention, the first side of the metal mesh is connected to the current collector, and the included angle ɑ1 between the first side and one side of the current collector along the length direction of the current collector satisfies the following relationship: 0° ≤ ɑ1 ≤ 90°, for example, ɑ1 is 0°, 30°, 45°, 60° or 90°.

[0010] Exemplarily, when the included angle ɑ1 = 0°, that is, the first side of the metal mesh is arranged parallel to one side of the current collector along the length direction of the current collector.

[0011] Exemplarily, when the included angle ɑ1 = 90°, that is, the first side of the metal mesh is arranged perpendicular to one side of the current collector along the length direction of the current collector.

[0012] According to the present invention, the included angle ɑ2 between the second side adjacent to the first side of the metal mesh and the plane where the current collector is located satisfies the following relationship: 0° ≤ ɑ2 ≤ 90°, for example, ɑ2 is 0°, 30°, 45°, 60° or 90°.

[0013] Exemplarily, when the included angle ɑ2 = 0°, the metal mesh is arranged parallel to the plane where the current collector is located, that is, the metal mesh is arranged on the surface of the current collector.

[0014] Exemplarily, when the included angle ɑ2 is between 0° and 90° and does not include the end values, the metal mesh is arranged obliquely on the surface of the current collector.

[0015] Exemplarily, when the included angle ɑ2 = 90°, the metal mesh is arranged perpendicular to the plane where the current collector is located.

[0016] According to the present invention, the length L2 of the second side adjacent to the first side of the metal mesh and the thickness d of the active material layer satisfy the following relationship: L2 × sinɑ2 ≤ d.

[0017] Exemplarily, the thickness d of the active material layer is 10 - 500 μm, for example, 10 μm, 20 μm, 50 μm, 80 μm, 100 μm, 120 μm, 150 μm, 180 μm, 200 μm, 220 μm, 2�0 μm, 280 μm, 300 μm, 350 μm, 380 μm, 400 μm, 450 μm, 480 μm or 500 μm.

[0018] Exemplarily, the length L2 of the second side of the metal mesh adjacent to the first side is 10 - 1000 μm, such as 10 μm, 20 μm, 50 μm, 80 μm, 100 μm, 120 μm, 150 μm, 180 μm, 200 μm, 220 μm, 250 μm, 280 μm, 300 μm, 350 μm, 380 μm, 400 μm, 450 μm, 480 μm, 500 μm, 550 μm, 600 μm, 650 μm, 700 μm, 750 μm, 800 μm, 850 μm, 900 μm, 950 μm or 1000 μm.

[0019] According to the present invention, the length L1 of the first side of the metal mesh and the width W of the current collector satisfy the following relationship: L1×sinɑ1 ≤ W.

[0020] Exemplarily, the width W of the current collector is 10 mm - 800 mm, such as 10 mm, 20 mm, 50 mm, 80 mm, 100 mm, 120 mm, 150 mm, 180 mm, 200 mm, 220 mm, 250 mm, 280 mm, 300 mm, 350 mm, 380 mm, 400 mm, 450 mm, 480 mm, 500 mm, 550 mm, 600 mm, 650 mm, 700 mm, 750 mm or 800 mm.

[0021] Exemplarily, the length L1 of the first side of the metal mesh is 10 mm - 2000 mm, such as 10 mm, 20 mm, 50 mm, 80 mm, 100 mm, 120 mm, 150 mm, 180 mm, 200 mm, 220 mm, 250 mm, 280 mm, 300 mm, 350 mm, 380 mm, 400 mm, 450 mm, 480 mm, 500 mm, 550 mm, 600 mm, 650 mm, 700 mm, 750 mm, 800 mm, 1000 mm, 1200 mm, 1500 mm, 1800 mm or 2000 mm.

[0022] According to the present invention, when the electrode sheet is applied to the negative electrode sheet, the metal mesh is selected from copper mesh.

[0023] According to the present invention, when the electrode sheet is applied to the positive electrode sheet, the metal mesh is selected from aluminum mesh.

[0024] According to the present invention, the mesh diameter of the metal mesh is b1, and the maximum particle size of the active material in the active material layer is b2.

[0025] Exemplarily, the maximum particle size b2 of the active material in the active material layer is 10 - 200 μm, such as 10 μm, 20 μm, 50 μm, 80 μm, 100 μm, 120 μm, 150 μm, 180 μm or 200 μm.

[0026] Exemplarily, the mesh hole diameter b1 of the metal mesh is b1≥100 nm, such as 100 nm, 200 nm, 500 nm, 800 nm, 1 μm, 2 μm, 5 μm, 10 μm or 20 μm.

[0027] According to the present invention, when the number of metal meshes is greater than 1, the distance c between adjacent metal meshes is the same or different, and the minimum distance c1 between adjacent metal meshes satisfies c1>b2, and the maximum distance c2 between adjacent metal meshes satisfies c2<L, where b2 is the maximum particle size of the active material in the active material layer, and L is the length of the current collector.

[0028] In the present invention, the distance c between adjacent metal meshes refers to the vertical distance between the first sides of two adjacent metal meshes arranged adjacent to each other.

[0029] Exemplarily, the length L of the current collector is 10 mm - 5000 mm, such as 10 mm, 20 mm, 50 mm, 80 mm, 100 mm, 120 mm, 150 mm, 180 mm, 200 mm, 220 mm, 250 mm, 280 mm, 300 mm, 350 mm, 380 mm, 400 mm, 450 mm, 480 mm, 500 mm, 550 mm, 600 mm, 650 mm, 700 mm, 750 mm, 800 mm, 1000 mm, 1200 mm, 1500 mm, 1800 mm, 2000 mm, 3000 mm, 3500 mm, 4000 mm or 5000 mm.

[0030] According to the present invention, the number of metal meshes is ≥1, and can be specifically adjusted according to the length of the current collector and the distance between adjacent metal meshes.

[0031] According to the present invention, when the electrode sheet is applied to a negative electrode sheet, the current collector is selected from copper foils, such as one of porous copper foils or etched copper foils.

[0032] According to the present invention, when the electrode sheet is applied to a positive electrode sheet, the current collector is selected from aluminum foils, such as one of porous aluminum foils or etched aluminum foils.

[0033] According to the present invention, the thickness of the current collector is 4 - 25 μm.

[0034] According to the present invention, the thickness of the metal mesh is 1 - 30 μm.

[0035] According to the present invention, the active material layer comprises an active material and a binder.

[0036] According to the present invention, the active material layer further comprises a conductive agent and a thickening agent.

[0037] According to the present invention, the active material layer comprises the following components in mass percentage:

[0038] (a) 60 - 99.9 wt% of active material; (b) 0 - 15 wt% of conductive agent; (c) 0.1 - 15 wt% of binder; (d) 0 - 10 wt% of thickening agent.

[0039] Preferably, the active material layer comprises the following components in mass percentage:

[0040] (a) 70 - 97 wt% of active material; (b) 1 - 10 wt% of conductive agent; (c) 1 - 10 wt% of binder; (d) 1 - 10 wt% of thickening agent.

[0041] According to the present invention, when the active material is a negative electrode active material, it is selected from at least one of graphite, hard carbon, soft carbon, silicon-based materials, tin-based materials, graphene, etc.

[0042] According to the present invention, when the active material is a positive electrode active material, it is selected from at least one of lithium cobalt oxide, lithium manganate, lithium iron phosphate, ternary materials, etc.

[0043] According to the present invention, the conductive agent is selected from one or more of superconducting carbon, carbon nanotubes, carbon black, etc.

[0044] According to the present invention, the binder is selected from one or more of styrene-butadiene rubber latex (SBR), polyacrylic acid (PAA), lithium polyacrylate (PAA-Li), sodium polyacrylate (PAA-Na), polyvinylidene fluoride (PVDF).

[0045] According to the present invention, the thickening agent is selected from one or more of sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, etc.

[0046] The present invention also provides a method for preparing the above-mentioned electrode sheet, and the method comprises the following steps:

[0047] (1) Weld the metal mesh and the current collector together by ultrasonic welding to obtain a current collector welded with the metal mesh;

[0048] (2) Prepare an active material slurry for forming the active material layer, and coat the active material slurry for forming the active material layer on the surface of the current collector welded with the metal mesh in step (1) to prepare the electrode sheet.

[0049] According to the present invention, in step (1), the metal mesh is, for example, prepared by an electrolysis method or a stamping method.

[0050] According to the present invention, in step (2), the method for preparing the positive electrode active material slurry for forming the positive electrode active material layer includes:

[0051] Adding the positive electrode active material, binder, conductive agent, and NMP into a planetary stirring tank, stirring at a stirring speed of 35 Hz for revolution and 2200 Hz for rotation for 5 h to fully mix and prepare a positive electrode slurry with an outlet viscosity of 3500 - 8000 mPa·s.

[0052] According to the present invention, in step (2), the method for preparing the negative electrode active material slurry for forming the negative electrode active material layer includes:

[0053] Adding the negative electrode active material, binder, thickener, conductive agent, and deionized water into a planetary stirring tank, stirring at a stirring speed of 38 Hz for revolution and 1200 Hz for rotation for 8 h to fully mix and prepare a negative electrode slurry with an outlet viscosity of 1500 - 6000 mPa·s.

[0054] The present invention also provides a lithium-ion secondary battery, which includes the above-mentioned electrode sheet.

[0055] Advantages of the present invention:

[0056] The present invention provides an electrode sheet and a lithium-ion secondary battery including the electrode sheet. The electrode sheet includes a current collector, a metal mesh, and an active material layer; the active material layer is provided on one or both surfaces of the current collector, and the metal mesh is embedded in the active material layer and connected to the current collector. The electrode sheet of the present invention forms a multi-current collector in a practical sense, which is beneficial to shortening the migration path of lithium ions, reducing the polarization of the electrode sheet, and improving the cycle performance of the lithium-ion secondary battery; when applied to the negative electrode sheet, it is beneficial to improving the charging ability of the negative electrode sheet, and when applied to the positive electrode sheet, it is beneficial to reducing the impedance of the positive electrode sheet and improving the rate performance of the lithium-ion secondary battery. Due to the presence of the multi-current collector, the loading amount of the active material can be greatly increased, which is thus beneficial to improving the energy density of the lithium-ion secondary battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 It is a schematic structural diagram of the electrode sheet according to a preferred embodiment of the present invention.

[0058] BRIEF DESCRIPTION OF THE DRAWINGS: 1 is the current collector; 2 is the active material layer; 3 is the metal mesh.

[0059] Figure 2 It is the test result of the electrode sheet impedance of the positive electrode sheets of Comparative Example 1 and Examples 1 - 4.

[0060] Figure 3Test results of the discharge performance of the lithium-ion batteries prepared from the positive electrode sheets of Comparative Example 1 and Examples 1-4 under different rate conditions.

[0061] Figure 4 Test results of the charge performance of the lithium-ion batteries prepared from the negative electrode sheets of Comparative Example 1 and Examples 5-9 under different rate conditions. Detailed implementation manners

[0062] The following will further elaborate on the present invention in conjunction with specific examples. It should be understood that the following examples are only for illustrative and explanatory purposes of the present invention, and should not be construed as limiting the protection scope of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope intended to be protected by the present invention.

[0063] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods; unless otherwise specified, the reagents, materials, etc. used in the following examples can all be obtained from commercial channels.

[0064] In the description of the present invention, it should be noted that the terms "first", "second", etc. are only used for descriptive purposes, and do not indicate or imply relative importance.

[0065] Comparative Example 1

[0066] Positive current collector: Aluminum foil with a thickness of 10 μm.

[0067] Negative current collector: Copper foil with a thickness of 8 μm.

[0068] Prepare the positive electrode paste:

[0069] Add 97.0 wt% of the positive electrode active material lithium cobalt oxide (maximum particle size b2 < 100 μm), 1.5 wt% of the binder PVDF (polyvinylidene fluoride), 1.5 wt% of the conductive agent Super P and a certain amount of NMP into a planetary stirring tank, and stir at a stirring speed of 35 Hz for revolution and 2200 Hz for rotation for 5 h to fully mix and prepare a positive electrode paste with an outlet viscosity of 3500 - 8000 mPa·s.

[0070] Coat the positive electrode paste on both side surfaces of the above positive current collector, and vacuum dry at 95 °C to prepare a positive electrode layer with a single-sided coating layer thickness of 120 μm.

[0071] Prepare the negative electrode paste:

[0072] Add 94.5 wt% of the anode active material graphite (maximum particle size b2 < 60 μm), 2.0 wt% of the binder SBR, 2.0 wt% of the thickener CMC-Na, 1.5 wt% of the conductive agent Super P (superconducting carbon), and a certain amount of deionized water into a planetary stirring tank, and stir at a stirring speed of 38 Hz for revolution and 1200 Hz for rotation for 8 hours to fully mix and prepare an anode slurry with an outlet viscosity of 1500 - 6000 mPa·s.

[0073] Coat the anode slurry on both side surfaces of the above-mentioned anode current collector, and vacuum dry at 90 °C to prepare an anode layer with a single-sided coating layer thickness of 150 μm.

[0074] The separator is a conventional substrate separator for lithium batteries, and the electrolyte is a commercial liquid electrolyte for lithium-ion batteries.

[0075] Wind the above-prepared positive electrode sheet, negative electrode sheet, and separator by a winding process and combine with a liquid electrolyte to make a lithium-ion battery.

[0076] Example 1

[0077] Others are the same as Comparative Example 1, the difference lies in the different anode current collectors:

[0078] Select a rectangular aluminum mesh with regular shape. The length of the first side of the aluminum mesh is the same as the width of the current collector. The length of the second side of the aluminum mesh is 100 μm, the mesh diameter of the aluminum mesh is 500 nm, and the thickness of the aluminum mesh is 20 μm.

[0079] Weld 6 aluminum meshes with the above structure on one side surface of the aluminum foil by ultrasonic welding method, and at the same time ensure that the first side of the aluminum mesh is connected to the current collector, and the first side of the aluminum mesh is perpendicular to one side of the current collector along the length direction of the current collector (ɑ1 = 90°), and the aluminum mesh is perpendicular to the plane where the current collector is located (ɑ2 = 90°); the distance between adjacent aluminum meshes is 10 cm to obtain the anode current collector.

[0080] Example 2

[0081] Others are the same as Comparative Example 1, the difference lies in the different anode current collectors:

[0082] Select a rectangular aluminum mesh with regular shape. The length of the first side of the aluminum mesh is the same as the width of the current collector. The length of the second side of the aluminum mesh is 100 μm, the mesh diameter of the aluminum mesh is 500 nm, and the thickness of the aluminum mesh is 20 μm.

[0083] Three aluminum meshes with the above structure are welded to one side surface of the aluminum foil by ultrasonic welding, and three aluminum meshes with the above structure are welded to the other side surface of the aluminum foil. At the same time, ensure that the first side of the aluminum mesh is connected to the current collector, and the first side of the aluminum mesh is perpendicular to one side of the current collector along the length direction of the current collector (ɑ1 = 90°), and the aluminum mesh is perpendicular to the plane where the current collector is located (ɑ2 = 90°); the distance between adjacent aluminum meshes is 10 cm, and the positive current collector is obtained.

[0084] Example 3

[0085] Other conditions are the same as in Example 1, except that twelve aluminum meshes with the above structure are welded to one side surface of the aluminum foil by ultrasonic welding, and the distance between adjacent aluminum meshes is 10 cm.

[0086] Example 4

[0087] Other conditions are the same as in Example 2, except that six aluminum meshes with the above structure are welded to one side surface of the aluminum foil by ultrasonic welding, six aluminum meshes with the above structure are welded to the other side surface of the aluminum foil, and the thicknesses of the positive electrode active material layers on both sides of the positive current collector are changed from the original 120 μm to 150 μm respectively.

[0088] Example 5

[0089] Other conditions are the same as in Comparative Example 1, except that the negative current collector is different:

[0090] Select a rectangular copper mesh with regular shape. The length of the first side of the copper mesh is the same as the width of the current collector. The length of the second side of the copper mesh is 100 μm. The mesh diameter of the copper mesh is 500 nm. The thickness of the copper mesh is 20 μm.

[0091] Six copper meshes with the above structure are welded to one side surface of the copper foil by ultrasonic welding. At the same time, ensure that the first side of the copper mesh is connected to the current collector, and the first side of the copper mesh is perpendicular to one side of the current collector along the length direction of the current collector (ɑ1 = 90°), and the copper mesh is perpendicular to the plane where the current collector is located (ɑ2 = 90°); the distance between adjacent copper meshes is 10 cm, and the negative current collector is obtained.

[0092] Example 6

[0093] Other conditions are the same as in Comparative Example 1, except that the negative current collector is different:

[0094] Select a rectangular copper mesh with regular shape. The length of the first side of the copper mesh is the same as the width of the current collector. The length of the second side of the copper mesh is 100 μm. The mesh diameter of the copper mesh is 500 nm. The thickness of the copper mesh is 20 μm.

[0095] Use ultrasonic welding to weld three copper meshes with the above structure on one side surface of the copper foil, and weld three copper meshes with the above structure on the other side surface of the copper foil. At the same time, ensure that the first side of the copper mesh is connected to the current collector, and the first side of the copper mesh is perpendicular to one side of the current collector along the length direction of the current collector (ɑ1 = 90°), and the copper mesh is perpendicular to the plane where the current collector is located (ɑ2 = 90°); the distance between adjacent copper meshes is 10 cm to obtain the negative current collector.

[0096] Example 7

[0097] Other conditions are the same as in Example 5, except that 12 copper meshes with the above structure are welded on one side surface of the copper foil by ultrasonic welding, and the distance between adjacent copper meshes is 10 cm.

[0098] Example 8

[0099] Other conditions are the same as in Example 6, except that 6 copper meshes with the above structure are welded on one side surface of the copper foil by ultrasonic welding, 6 copper meshes with the above structure are welded on the other side surface of the copper foil, and the thickness of the negative active material layer on both sides of the negative current collector is changed from the original 150 μm to 160 μm respectively.

[0100] Example 9

[0101] Other conditions are the same as in Example 5, except that the length of the second side of the copper mesh becomes 150 μm.

[0102] Test Example 1

[0103] The positive electrode sheets prepared in Comparative Example 1 and Examples 1-9 were subjected to electrode impedance tests (tested using a four-probe tester) under the same conditions, and the data are as Figure 2 shown in Table 1.

[0104] The lithium-ion secondary batteries prepared from the positive electrode sheets prepared in Comparative Example 1 and Examples 1-4 were subjected to discharge performance tests under different rate conditions, and the data are as Figure 3 shown in Table 1.

[0105] Among them, the rate discharge performance test is to charge the battery at a constant current and constant voltage with a certain current, and then discharge it at a current of 0.2C to obtain the battery capacity under 0.2C discharge; the test conditions for other rate discharges are the same as above, except that the discharge current is different; the ratio of the battery capacity under different rate discharges to the battery capacity under 0.2C rate is used to obtain the discharge performance data under different rate conditions, and the specific test results are shown in Table 1.

[0106] The lithium-ion secondary batteries prepared from the negative electrode sheets prepared in Comparative Example 1 and Examples 5-9 were subjected to charge performance tests under different rate conditions, and the data are as Figure 4 shown in Table 1.

[0107] Among them, the rate charging performance test is to discharge to 3.0V with a certain current constant current, and then fully charge at a constant current and constant voltage current with a current of 0.2C. The ratio of the charging capacity in the constant current stage to the capacity in the entire charging stage is obtained as the constant current charging ratio under the 0.2C charging rate; the test conditions for other rate charging are the same as above, the difference is that the charging current is different, and the charging performance data under different rate conditions are obtained. The specific test results are shown in Table 1.

[0108] Table 1 Performance test results of lithium ion secondary batteries of Examples 1-9 and Comparative Example 1

[0109]

[0110] In Table 1, Examples 1-4 were used as positive electrodes, and the effects of the positive electrodes on the rate discharge performance of lithium-ion batteries were mainly investigated, with a focus on the impedance and rate discharge performance of the positive electrodes. Examples 5-9 were used as negative electrodes, and the effects of the negative electrodes on the rate charge performance of lithium-ion batteries were mainly investigated.

[0111] In addition, combining Table 1 and Figures 2 - 4 , we can get the following results:

[0112] Combined with Table 1 and Figure 2 The test results shown show that the positive electrode sheet of the present invention has a smaller electrode impedance. When the thickness of the positive electrode coating increases, the electrode impedance increases, but it still has an advantage over Comparative Example 1, indicating that the positive electrode sheet of the present invention supports a higher positive electrode active material loading, increases the positive electrode sheet surface density, and is beneficial to improving the battery energy density.

[0113] Combined with Table 1 and Figure 3 The test results shown indicate that the lithium-ion battery produced using the positive electrode sheet of the present invention has better rate discharge performance, and has significant advantages for applications requiring high rate discharge performance, such as power tools and start-stop power supplies.

[0114] Combined with Table 1 and Figure 4 As shown, the capacity of the battery produced by the negative electrode sheet of the present invention in the constant current stage accounts for a higher proportion of the total charging capacity of the battery, that is, the constant current charging ratio is higher. The constant current charging ratio is an indicator of the fast charging capability of the battery. The charging speed of the battery mainly depends on the proportion of the capacity in the constant current charging stage. The higher the constant current charging ratio, the better the fast charging performance of the battery and the shorter the time it takes to fully charge the battery. Figure 4 The test results also show that the thickness of the electrode of the present invention is increased, that is, the active material loading is increased, and the effect is still obvious, which plays a great role in improving the energy density of the battery under the fast charging system.

[0115] The above describes the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A pole piece, wherein: The electrode includes a current collector, a metal mesh, and an active material layer; the active material layer is disposed on one or both surfaces of the current collector, and the metal mesh is embedded in the active material layer and connected to the current collector; The metal mesh includes a first side and a second side adjacent to the first side; The first side of the metal mesh is connected to the current collector, and the included angle ɑ1 between the first side and one side of the current collector along the length direction of the current collector satisfies the following relationship: 0°≤ɑ1≤90°; the included angle ɑ2 between the second side adjacent to the first side of the metal mesh and the plane where the current collector is located satisfies the following relationship: 0°<ɑ2≤90°; The distances c between adjacent metal meshes are the same or different, and the minimum distance c1 between adjacent metal meshes satisfies c1>b2, and the maximum distance c2 between adjacent metal meshes satisfies c2<L, where b2 is the maximum particle size of the active material in the active material layer, and L is the length of the current collector; The thickness d of the active material layer is 10 - 500 μm.

2. The pole piece according to claim 1, wherein: The shape of the metal mesh is a rectangular structure.

3. The pole piece according to claim 1, wherein: The length L2 of the second side adjacent to the first side of the metal mesh and the thickness d of the active material layer satisfy the following relationship: L2×sinɑ2≤d; and / or, The length L2 of the second side adjacent to the first side of the metal mesh is 10 - 1000 μm.

4. The pole piece according to any one of claims 1 to 3, wherein: The length L1 of the first side of the metal mesh and the width W of the current collector satisfy the following relationship: L1×sinɑ1≤W; and / or, The width of the current collector is 10 mm - 800 mm; and / or, The length L1 of the first side of the metal mesh is 10 mm - 2000 mm.

5. The pole piece according to any one of claims 1 to 3, wherein: When the electrode is applied to a negative electrode, the metal mesh is selected from a copper mesh; and / or, When the electrode is applied to a positive electrode, the metal mesh is selected from an aluminum mesh; and / or, When the electrode is applied to a negative electrode, the current collector is selected from a copper foil; and / or, When the electrode is applied to a positive electrode, the current collector is selected from an aluminum foil.

6. The pole piece according to any one of claims 1 to 3, wherein: The maximum particle size b2 of the active material in the active material layer is 10 - 200 μm; and / or, The mesh diameter b1 of the metal mesh is b1≥100 nm.

7. The pole piece according to any one of claims 1 to 3, wherein: The length L of the current collector is 10 mm - 5000 mm.

8. The pole piece according to any one of claims 1 to 3, wherein: The active material layer includes an active material and a binder; and / or, The active material layer further includes a conductive agent and a thickening agent; and / or, The active material layer includes the following components in mass percentage: (a) active material 60 - 99.9 wt%; (b) conductive agent 0 - 15 wt%; (c) binder 0.1 - 15 wt%; (d) thickening agent 0 - 10 wt%.

9. A lithium-ion secondary battery, the lithium-ion secondary battery includes the electrode according to any one of claims 1 - 8.

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