Processing method of positive pole piece, positive pole piece and lithium battery

Abstract

The invention provides a processing method of a positive pole piece, the positive pole piece and a lithium battery, and the processing method comprises the following steps: presetting the laser wavelength of nanosecond laser, and emitting the nanosecond laser; controlling the laser beam through a two-dimensional galvanometer scanner with a preset focal length and a light spot diameter, so that the irradiated laser beam is in Gaussian distribution; and the positive pole piece is circularly scanned through the laser beam, the number of times of circular scanning is smaller than or equal to three, and a groove with a preset aspect ratio is formed in the surface of the positive pole piece. The rate capability and the discharge capacity of the positive pole piece can be improved, and the cost of the lithium battery is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of battery pole piece processing, and in particular to a positive pole piece processing method, a positive pole piece and a lithium battery. Background Art

[0002] Lithium-ion batteries are composed of positive electrodes, negative electrodes, separators, and electrolytes. The positive and negative electrodes determine the capacity and operating voltage of the battery and can be made of a variety of materials, such as LiCoO2, LiMn2O4, LiNiMnCoO2, and LiFePO4. Among them, LiFePO4, as a typical positive electrode material, has excellent stability and cycle life, and has a relatively low specific capacity. However, due to the covalent bond structure of LiFePO4, the ionic conductivity of LiFePO4 is low, and the low ionic conductivity leads to poor rate performance (rate performance refers to the ability to maintain the original capacity during rapid charging and discharging), and the poor rate performance causes the battery to rapidly decrease in capacity during rapid charging and discharging. In order to solve this problem, the prior art has improved the materials and structures of the battery to improve the low conductivity. For example, T. Tsuda et al. manufactured parallel batteries with balanced and unbalanced LFP / LFP cathodes to evaluate high-rate discharge performance, but this setting method resulted in internal resistance mismatch, unbalanced cathodes, and lower discharge capacity at high rates, resulting in faster capacity decay. Summary of the invention

[0003] In order to overcome the defects in the prior art, the embodiments of the present invention provide a method for processing a positive electrode plate, a positive electrode plate and a lithium battery, which can improve the rate performance and discharge capacity of the positive electrode plate and reduce the cost of the lithium battery.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] The first aspect of the present invention discloses a method for processing a positive electrode sheet, comprising:

[0006] Presetting the laser wavelength of the nanosecond laser and emitting the nanosecond laser;

[0007] The laser beam is controlled by a two-dimensional galvanometer scanner having a preset focal length and spot diameter so that the irradiated laser beam has a Gaussian distribution;

[0008] The positive electrode plate is cyclically scanned by the laser beam, and the number of cyclic scanning is less than or equal to three times, so that a groove with a preset aspect ratio is formed on the surface of the positive electrode plate.

[0009] The above technical solution uses a nanosecond laser process to perform structured processing on the positive electrode plate, and forms a groove with a preset aspect ratio on the positive electrode plate according to preset parameters, which can shorten the distance that lithium ions are transmitted between the positive electrode plate and the negative electrode plate, and reduce the diffusion of lithium ions in the solid phase of the positive electrode plate, thereby improving the rate performance of the positive electrode plate, improving low conductivity, and increasing the discharge capacity of the positive electrode plate, thereby improving the cycle performance of the lithium battery. The present application processes the electrode plate with a nanosecond laser of a preset wavelength, which can avoid the generation of dust or electrode penetration during electrode plate processing, improve the stability of electrode plate processing, and avoid damaging the electrode plate while improving the rate performance of the electrode plate. The processing method is not only efficient and simple but also low-cost.

[0010] Furthermore, when the positive electrode plate is cyclically scanned by the laser beam, the laser parameters also include energy density, pulse duration, pulse repetition frequency and scanning speed.

[0011] When the wavelength of the laser beam meets the preset value, other laser parameter values ​​can be set according to the wavelength to ensure that the laser beam overlap rate reaches the preset value during scanning, thereby improving the processing quality of the electrode surface. During laser scanning, if the number of scans is too many, the depth of the groove formed will increase, and the rate performance will not change much. However, multiple scans are prone to generate dust and are difficult to clean, resulting in increased self-discharge of the electrode, affecting the cycle performance. In addition, excessive accumulated heat from the laser will cause the rubber layer to fall off and the positive electrode material area to fall off, thereby damaging the electrode. When the number of scans is less than or equal to three, its rate performance is significantly improved.

[0012] Furthermore, the laser wavelength is 1000-1064um, the spot diameter of the two-dimensional galvanometer scanner is 29-31um, and the focal length is 160-164mm.

[0013] When the wavelength is smaller, the energy generated by the laser is higher, the damage to the positive electrode is greater, and the more dust is generated, resulting in serious self-discharge of the battery cell. Its rate performance is significantly reduced and affects the safety of the battery cell. When the wavelength is too large, the groove depth is too deep and even the aluminum foil may be exposed. When the laser wavelength is within 1000~1064um, its rate performance is significantly improved.

[0014] When the spot diameter is too large, the width of the groove formed by scanning is too large, resulting in a decrease in the pole piece rate performance. When the spot diameter is too small, the width of the groove formed by scanning is too small and its regularity cannot be controlled, and thus a pole piece with consistent morphology cannot be formed. When the spot diameter is between 29 and 31 um, its rate performance is significantly improved.

[0015] If the focal length is too short, the laser beam scanning range is small, resulting in poor consistency of the pole piece, thereby reducing the magnification performance. If the focal length is too large, the laser beam energy is low, and dust is easily generated when scanning the pole piece, increasing the subsequent pole piece foreign matter, thereby increasing safety hazards.

[0016] Furthermore, the aspect ratio of the groove is 0.3 to 1. By forming a groove in the material area of ​​the positive electrode sheet by laser, and controlling the aspect ratio of the groove to 0.3 to 1 by preset focal length and spot diameter, the effect of improving the rate performance of the battery cell can be optimized.

[0017] Furthermore, the material of the positive electrode plate is lithium iron phosphate, and the thickness of the positive electrode plate is less than or equal to 300um.

[0018] Furthermore, the two-dimensional galvanometer scanner is also provided with a lens, and there is a preset distance between the lens and the positive electrode plate, and the preset distance is 185-190 mm.

[0019] The second aspect of the present invention discloses a positive electrode plate, which is produced by the processing method described in any one of the first aspects, and at least one groove is provided on the surface of the positive electrode plate, wherein at least one groove extends to the edges of the two sides of the positive electrode plate, so that at least one groove is connected to the outside of the positive electrode plate.

[0020] The connection between the groove and the edges of both sides of the positive electrode plate can ensure the consistency of the current density of the entire electrode plate, avoid concentration polarization caused by inconsistent current density and lead to lithium precipitation in the later stage, so that the battery can work stably during the charging and discharging process, reducing capacity attenuation and safety hazards.

[0021] Furthermore, the groove is in the shape of a continuous long strip, and both ends of the groove extend to the edges of two sides of the positive electrode sheet respectively.

[0022] Furthermore, the positive electrode plate has more than two mutually disconnected grooves, wherein ends of at least two grooves that are away from each other extend to the edges of two side edges of the positive electrode plate respectively.

[0023] Furthermore, the two or more mutually disconnected grooves are arranged in a preset form, and there is a preset interval between adjacent grooves.

[0024] A third aspect of the present invention discloses a lithium battery, comprising a lithium battery body, wherein the lithium battery adopts the positive electrode plate as described in any one of the second aspects as the positive electrode plate of the lithium battery.

[0025] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0026] 1. The present application uses nanosecond laser to perform structural processing on the positive electrode plate, and forms a groove with a preset aspect ratio according to preset laser parameters, which can improve the low conductivity of the positive electrode plate and enhance the rate performance of the positive electrode plate, thereby enhancing the discharge capacity of the positive electrode plate. Moreover, the processing of the positive electrode plate by nanosecond laser is not only efficient, simple and low-cost, but also avoids damaging the plate while improving the rate performance of the plate.

[0027] 2. The present application uses laser technology to perform structural processing on the positive electrode plate, which can increase the discharge capacity of the positive electrode plate by 2% to 6%, thereby reducing the usage of lithium iron phosphate, thereby further reducing the BOM cost of the battery cell.

[0028] In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 This is a schematic diagram of a process for processing a positive electrode sheet provided in an embodiment of the present application;

[0031] Figure 2 is a top view of a groove structure provided in an embodiment of the present application;

[0032] Figure 3 This is a top view of another groove structure provided in an embodiment of the present application.

[0033] The figure markings of the above drawings are: 1. laser; 2. two-dimensional galvanometer scanner; 3. lens; 4. positive electrode plate; 5. groove. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. In addition, the drawings of the present invention are only simple schematic illustrations and are not depicted according to actual sizes. Please note in advance.

[0035] In the present invention, it should be noted that the terms "upper", "lower", "inside", "outside", "forward", "backward", "between", "close to", "far away" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention. It should also be noted that, unless otherwise clearly specified and limited, the terms "installation" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0036] It should be understood that, although the terms "first", "second", "third", etc. may be used herein to describe various components or signals, these components or signals should not be limited by these terms. These terms are mainly used to distinguish one component from another component, or one signal from another signal. In addition, the term "or" used herein may include any one or more combinations of the associated listed items depending on the actual situation.

[0037] Reference Figure 1 As shown, an embodiment of the present application provides a device for processing a positive electrode sheet, comprising:

[0038] Laser 1, which is a nanosecond laser, is used to emit nanosecond laser. The frequency of nanosecond laser is high, and the emitted laser beam can scan a specific area on the positive electrode plate 4 without damaging other electrode plate areas.

[0039] The two-dimensional galvanometer scanner 2 includes a two-dimensional galvanometer and a control system. The two-dimensional galvanometer is composed of two reflectors. The two reflectors are regulated by a high-precision motor to control the direction and position of the laser beam, so as to achieve a precise scanning function by deflecting the laser beam. Figure 1 As shown, in a possible embodiment, the galvanometer scanner 2 is further equipped with a lens 3. When scanning the positive electrode plate 4, there is a preset distance between the lens 3 and the positive electrode plate 4, and the preset distance is 185 to 190 mm.

[0040] It should be noted that the models of the laser and the two-dimensional galvanometer scanner in the present application can be selected according to actual conditions, as long as the selected laser can meet the set wavelength range and the two-dimensional galvanometer scanner meets the set focal length and spot diameter. In the embodiments of the present application, a laser and a two-dimensional galvanometer scanner are selected by way of example, for example, an InnoLas Photonics 355-1-V laser and a SCAN cubeIII 14 two-dimensional galvanometer scanner are selected, and the positive electrode plate is processed within the set wavelength range by means of this laser.

[0041] In the embodiment of the present application, the material of the positive electrode plate 4 is lithium iron phosphate, and the thickness of the positive electrode plate 4 is less than or equal to 300 um.

[0042] The positive electrode sheet 4 is scanned and processed by the above-mentioned device for processing the positive electrode sheet of a lithium battery. The processing method includes the following steps:

[0043] Preset the laser wavelength of the nanosecond laser.

[0044] In an embodiment of the present application, the preset laser wavelength is 1000~1064um. When the wavelength of the laser beam meets the preset value, other laser parameter values ​​can be set according to the wavelength, including energy density, pulse duration, pulse repetition frequency and scanning speed, to ensure that the laser beam overlap rate during scanning is 96.67%, thereby improving the processing quality of the pole piece surface.

[0045] In the embodiment of the present application, the energy density of the laser is 0.28 J / cm 2 ~1.30J / cm 2 , pulse duration is 4ns, pulse repetition frequency is 500kHz, and scanning speed is 500mm / s.

[0046] The laser beam of the laser 1 is controlled by a two-dimensional galvanometer scanner 2 with a preset spot diameter and focal length, so that the irradiated laser beam presents a Gaussian distribution.

[0047] Optionally, the spot diameter is 29-31 um, and the focal length is 160-164 mm.

[0048] The positive electrode plate 4 is cyclically scanned by the laser beam, and the number of cyclic scanning is less than or equal to three times, so that a groove with a preset aspect ratio is formed on the surface of the positive electrode plate 4. The aspect ratio of the groove is the ratio of the width to the depth of the groove, and optionally, the aspect ratio of the groove is 0.3-1.

[0049] The positive electrode plate 4 processed according to the above method has grooves formed in the material area of ​​the positive electrode plate 4, so that the lithium ions have a shorter transmission path, a larger surface area and good wettability, which can improve the diffusion behavior of lithium ions, thereby improving the rate performance of the lithium iron phosphate positive electrode and improving the discharge capacity.

[0050] The present invention is described in detail below in conjunction with embodiments:

[0051] Embodiment 1:

[0052] Process the positive electrode according to the following parameters:

[0053] The wavelength of the InnoLas Photonics 355-1-V laser was set to 1064 μm and the laser energy density was set to 0.5 J / cm 2 , the pulse duration, pulse repetition frequency, and scanning speed were set to 4 ns, 500 kHz, and 500 mm / s, respectively, and nanosecond laser was emitted;

[0054] The SCAN cubeIII 14 two-dimensional galvanometer scanner was set on the emission path of the laser beam, and the direction and position of the laser beam were controlled so that the irradiated laser beam had a Gaussian distribution. The focal length of the SCAN cubeIII 14 two-dimensional galvanometer scanner was 163 mm, and the spot diameter was 30 μm.

[0055] The lens 3 is set on the emission path of the laser beam, and the distance between the lens 3 and the surface of the positive electrode plate 4 is 189 mm;

[0056] The laser beam scans the positive electrode twice in a cycle.

[0057] Embodiment 2:

[0058] Process the positive electrode according to the following parameters:

[0059] The wavelength of the InnoLas Photonics 355-1-V laser was set to 1064 μm and the laser energy density was set to 0.5 J / cm 2 , the pulse duration, pulse repetition frequency, and scanning speed were set to 4 ns, 500 kHz, and 500 mm / s, respectively, and nanosecond laser was emitted;

[0060] The SCAN cubeIII 14 two-dimensional galvanometer scanner was set on the emission path of the laser beam, and the direction and position of the laser beam were controlled so that the irradiated laser beam had a Gaussian distribution. The focal length of the SCAN cubeIII 14 two-dimensional galvanometer scanner was 163 mm, and the spot diameter was 30 μm.

[0061] The lens 3 is set on the emission path of the laser beam, and the distance between the lens 3 and the surface of the positive electrode plate 4 is 189 mm;

[0062] The laser beam scans the positive electrode plate 3 times in a cycle.

[0063] Embodiment three:

[0064] Process the positive electrode according to the following parameters:

[0065] The wavelength of the InnoLas Photonics 355-1-V laser was set to 1064 μm and the laser energy density was set to 0.5 J / cm 2 , the pulse duration, pulse repetition frequency, and scanning speed were set to 4 ns, 500 kHz, and 500 mm / s, respectively, and nanosecond laser was emitted;

[0066] The SCAN cubeIII 14 two-dimensional galvanometer scanner was set on the emission path of the laser beam, and the direction and position of the laser beam were controlled so that the irradiated laser beam had a Gaussian distribution. The focal length of the SCAN cubeIII 14 two-dimensional galvanometer scanner was 163 mm, and the spot diameter was 50 μm.

[0067] The lens 3 is set on the emission path of the laser beam, and the distance between the lens 3 and the surface of the positive electrode plate 4 is 189 mm;

[0068] The laser beam scans the positive electrode plate 3 times in a cycle.

[0069] Embodiment 4:

[0070] The wavelength of the InnoLas Photonics 355-1-V laser was set to 1000 μm and the laser energy density was set to 0.5 J / cm 2 , the pulse duration, pulse repetition frequency, and scanning speed were set to 4 ns, 500 kHz, and 500 mm / s, respectively, and nanosecond laser was emitted;

[0071] The SCAN cubeIII 14 two-dimensional galvanometer scanner was set on the emission path of the laser beam, and the direction and position of the laser beam were controlled so that the irradiated laser beam had a Gaussian distribution. The focal length of the SCAN cubeIII 14 two-dimensional galvanometer scanner was 163 mm, and the spot diameter was 30 μm.

[0072] The lens 3 is set on the emission path of the laser beam, and the distance between the lens 3 and the surface of the positive electrode plate 4 is 189 mm;

[0073] The laser beam scans the positive electrode plate 3 times in a cycle.

[0074] Embodiment five:

[0075] The wavelength of the InnoLas Photonics 355-1-V laser was set to 1000 μm and the laser energy density was set to 0.5 J / cm 2 , the pulse duration, pulse repetition frequency, and scanning speed were set to 4 ns, 500 kHz, and 500 mm / s, respectively, and nanosecond laser was emitted;

[0076] The SCAN cubeIII 14 two-dimensional galvanometer scanner was set on the emission path of the laser beam, and the direction and position of the laser beam were controlled so that the irradiated laser beam had a Gaussian distribution. The focal length of the SCAN cubeIII 14 two-dimensional galvanometer scanner was 163 mm, and the spot diameter was 30 μm.

[0077] The lens 3 is set on the emission path of the laser beam, and the distance between the lens 3 and the surface of the positive electrode plate 4 is 189 mm;

[0078] The laser beam scans the positive electrode twice in a cycle.

[0079] Embodiment six:

[0080] Process the positive electrode according to the following parameters:

[0081] The wavelength of the InnoLas Photonics 355-1-V laser was set to 1000 μm and the laser energy density was set to 0.5 J / cm 2 , the pulse duration, pulse repetition frequency, and scanning speed were set to 4 ns, 500 kHz, and 500 mm / s, respectively, and nanosecond laser was emitted;

[0082] The SCAN cubeIII 14 two-dimensional galvanometer scanner was set on the emission path of the laser beam, and the direction and position of the laser beam were controlled so that the irradiated laser beam had a Gaussian distribution. The focal length of the SCAN cubeIII 14 two-dimensional galvanometer scanner was 163 mm, and the spot diameter was 30 μm.

[0083] The lens 3 is set on the emission path of the laser beam, and the distance between the lens 3 and the surface of the positive electrode plate 4 is 189 mm;

[0084] The laser beam scans the positive electrode plate 4 times in a cycle.

[0085] Embodiment seven:

[0086] The wavelength of the InnoLas Photonics 355-1-V laser was set to 800 μm and the laser energy density was set to 0.5 J / cm 2 , the pulse duration, pulse repetition frequency, and scanning speed were set to 4 ns, 500 kHz, and 500 mm / s, respectively, and nanosecond laser was emitted;

[0087] The SCAN cubeIII 14 two-dimensional galvanometer scanner was set on the emission path of the laser beam, and the direction and position of the laser beam were controlled so that the irradiated laser beam had a Gaussian distribution. The focal length of the SCAN cubeIII 14 two-dimensional galvanometer scanner was 163 mm, and the spot diameter was 30 μm.

[0088] The lens 3 is set on the emission path of the laser beam, and the distance between the lens 3 and the surface of the positive electrode plate 4 is 189 mm;

[0089] The laser beam scans the positive electrode twice in a cycle.

[0090] Embodiment eight:

[0091] Process the positive electrode according to the following parameters:

[0092] The wavelength of the InnoLas Photonics 355-1-V laser was set to 1064 μm and the laser energy density was set to 0.5 J / cm 2 , the pulse duration, pulse repetition frequency, and scanning speed were set to 4 ns, 500 kHz, and 500 mm / s, respectively, and nanosecond laser was emitted;

[0093] The SCAN cubeIII 14 two-dimensional galvanometer scanner was set on the emission path of the laser beam, and the direction and position of the laser beam were controlled so that the irradiated laser beam had a Gaussian distribution. The focal length of the SCAN cubeIII 14 two-dimensional galvanometer scanner was 163 mm, and the spot diameter was 20 μm.

[0094] The lens 3 is set on the emission path of the laser beam, and the distance between the lens 3 and the surface of the positive electrode plate 4 is 189 mm;

[0095] The laser beam scans the positive electrode plate 3 times in a cycle.

[0096] Embodiment nine:

[0097] Process the positive electrode according to the following parameters:

[0098] The wavelength of the InnoLas Photonics 355-1-V laser was set to 1100 μm and the laser energy density was set to 0.5 J / cm 2 , the pulse duration, pulse repetition frequency, and scanning speed were set to 4 ns, 500 kHz, and 500 mm / s, respectively, and nanosecond laser was emitted;

[0099] The SCAN cubeIII 14 two-dimensional galvanometer scanner was set on the emission path of the laser beam, and the direction and position of the laser beam were controlled so that the irradiated laser beam had a Gaussian distribution. The focal length of the SCAN cubeIII 14 two-dimensional galvanometer scanner was 163 mm, and the spot diameter was 30 μm.

[0100] The lens 3 is set on the emission path of the laser beam, and the distance between the lens 3 and the surface of the positive electrode plate 4 is 189 mm;

[0101] The laser beam scans the positive electrode twice in a cycle.

[0102] The above embodiment also provides a lithium-ion battery assembled using the above positive electrode sheet, and the specific lithium-ion battery formula is as follows:

[0103] The positive electrode sheet of the lithium battery (16.0 mg / cm2 on each side) is composed of lithium iron phosphate (LFP), conductive carbon black (SuperP), polyvinylidene fluoride (PVDF5130) and carbon nanotubes (CNT) in a weight ratio of 96:1.8:1.7:0.5, and is processed according to the above-mentioned treatment method.

[0104] The negative electrode sheet of the lithium battery (10.1 mg / cm2 per side) includes graphite, polyacrylic acid binder (LA136D), conductive carbon black (Super P), carbon nanotubes (CNT) and carboxymethyl cellulose (CMC), and the weight ratio is 96:2.3:0.9:0.4:0.4. The ratio of the negative electrode capacity to the positive electrode capacity of the lithium battery (N / P value) is 1.08 to 1.18;

[0105] The electrolyte of the lithium battery includes ethyl methyl carbonate (EMC) and 1M lithium hexafluorophosphate (LiPF6) or ethylene carbonate (EC), and the volume ratio of EMC to 1M LiPF6 or EC is 7:3;

[0106] The separators for lithium batteries include polyethylene films coated with ceramic;

[0107] The negative electrode current collector of the lithium battery adopts a copper foil with a thickness of 6.0 μm, and is assembled into a battery according to the conventional assembly method of lithium-ion batteries. The charge and discharge range of the lithium battery is 2.0 to 4.5V.

[0108] Comparative Example 1: The positive electrode plate is not subjected to laser processing. A lithium-ion battery is assembled according to the same lithium-ion battery formula as in the above-mentioned embodiments 1 to 9.

[0109] The rate performance and cycle performance tests were performed on the batteries prepared in the above Examples 1-9 and Comparative Example 1, respectively, and the results are shown in Table 1.

[0110] Table 1

[0111]

[0112] It can be seen from Table 1 that the rate performance of the pole piece after nano-laser treatment is significantly greater than the rate performance of the untreated pole piece. Among them, when the laser wavelength is in the range of 1000-1064um, the spot diameter is in the range of 29-31um, and the number of scans is within three times, the rate performance and cycle performance improvement of the pole piece reach the best effect, which is 12%-28% higher than that of the untreated pole piece. At the same time, due to the improvement of dynamic performance, its cycle performance is also improved accordingly.

[0113] like Figure 2-3 As shown, an embodiment of the present application provides a positive electrode plate, which is processed by the processing method described in the above embodiment, and at least one groove is provided on the surface of the positive electrode plate, wherein at least one groove extends to the edges of the two side edges of the positive electrode plate, so that at least one groove is connected to the outside of the positive electrode plate.

[0114] In the embodiments of the present application, the groove can be a continuous groove or a plurality of mutually disconnected grooves. A continuous groove is a groove with an uninterrupted portion between the two ends, and a mutually disconnected groove is a groove with a gap between adjacent grooves, and the gap can be set according to actual conditions. The edges of the two sides of the positive electrode sheet can be two adjacent sides or two opposite sides.

[0115] like Figure 2 As shown, a continuous long strip groove 5 is provided on the surface of the positive electrode sheet 4. In the embodiment of the present application, the long strip groove 5 extends along the length direction of the positive electrode sheet 4, and the two ends of the long strip groove 5 extend to the edges of the two opposite sides of the positive electrode sheet 4, respectively, so that the long strip groove 5 is connected with the outside of the positive electrode sheet 4, so that the current density on the surface of the positive electrode sheet 4 is kept consistent. In the embodiment of the present application, the groove is connected with the outside of the positive electrode sheet so that the end faces of the two ends of the groove are in the same plane as the side of the positive electrode sheet.

[0116] In other possible embodiments, more than two long strip grooves can be set. Without considering the complexity of the process, the shape of the continuous groove can also be set to a broken line shape, a curve shape, etc. The continuous groove can extend along other directions of the positive electrode plate to ensure that the two ends of the continuous groove extend to the edges of both sides of the plate.

[0117] like Figure 3As shown, a plurality of mutually disconnected long strip grooves 5 are provided on the surface of the positive electrode plate 4. In the embodiment of the present application, the plurality of mutually disconnected long strip grooves 5 extend along the length direction of the positive electrode plate 4 and are located on the same horizontal line, wherein the ends of the two grooves farthest from each other in the plurality of mutually disconnected long strip grooves 5 respectively extend to the edges of the two opposite sides of the positive electrode plate 4, so that the current density on the surface of the positive electrode plate 4 remains consistent.

[0118] Of course, without considering the complexity of the process, multiple mutually disconnected grooves can be arranged in a broken line shape, a curve shape, etc. as a whole, wherein each groove can be rectangular, triangular, polygonal, circular, elliptical or irregularly shaped, etc.

[0119] Among them, more than two mutually disconnected grooves are arranged according to a preset shape, and there is a preset interval between adjacent grooves, so that multiple mutually disconnected grooves can be arranged on the positive electrode sheet in the same arrangement pattern. The preset shape includes but is not limited to the same extension direction, the position distribution of the grooves, and the preset interval size can be set according to actual conditions.

[0120] The cross section formed by the groove along the thickness direction of the positive electrode sheet can be of various shapes. Preferably, the cross section formed by the groove along the thickness direction of the positive electrode sheet is rectangular to ensure the uniformity of the current density and the sheet.

[0121] An embodiment of the present application further provides a lithium battery, including a lithium battery body, wherein the lithium battery uses the positive electrode plate described in the above embodiment as the positive electrode plate of the lithium battery.

[0122] The present invention uses specific embodiments to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A method for processing a positive electrode sheet, characterized in that: include: Presetting the laser wavelength of the nanosecond laser and emitting the nanosecond laser; The laser beam is controlled by a two-dimensional galvanometer scanner having a preset focal length and spot diameter so that the irradiated laser beam has a Gaussian distribution; The positive electrode plate is cyclically scanned by the laser beam, and the number of cyclic scanning is less than or equal to three times, so that a groove with a preset aspect ratio is formed on the surface of the positive electrode plate.

2. A method for processing a positive electrode sheet according to claim 1, characterized in that: The laser wavelength is 1000-1064um, the spot diameter of the two-dimensional galvanometer scanner is 29-31um, and the focal length is 160-164mm.

3. A method for processing a positive electrode sheet according to claim 1, characterized in that: The aspect ratio of the groove is 0.3-1.

4. A method for processing a positive electrode sheet according to claim 1, characterized in that: The material of the positive electrode plate is lithium iron phosphate, and the thickness of the positive electrode plate is less than or equal to 300um.

5. A method for processing a positive electrode sheet according to claim 1, characterized in that: The two-dimensional galvanometer scanner is also provided with a lens, and there is a preset distance between the lens and the positive electrode plate, and the preset distance is 185-190 mm.

6. A positive electrode sheet, characterized in that: The positive electrode plate is obtained by the processing method according to any one of claims 1 to 5, and at least one groove is provided on the surface of the positive electrode plate, wherein at least one groove extends to the edges of the two sides of the positive electrode plate, so that at least one groove is connected to the outside of the positive electrode plate.

7. A positive electrode sheet according to claim 6, characterized in that: The groove is in the shape of a continuous long strip, and both ends of the groove extend to the edges of the two sides of the positive electrode sheet respectively.

8. The positive electrode sheet according to claim 6, characterized in that: The positive electrode plate has more than two mutually disconnected grooves, wherein at least two of the mutually distant ends of the grooves extend to the edges of two side edges of the positive electrode plate respectively.

9. A positive electrode sheet according to claim 8, characterized in that: The two or more mutually disconnected grooves are arranged in a preset form, and there is a preset interval between adjacent grooves.

10. A lithium battery, comprising a lithium battery body, characterized in that: The lithium battery adopts the positive electrode sheet as described in any one of claims 6 to 9 as the positive electrode sheet of the lithium battery.

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