Current collector and preparation method thereof, pole piece and preparation method thereof, battery and electric device

Abstract

The invention discloses a current collector and a preparation method thereof, a pole piece and a preparation method thereof, a battery and an electric device. The current collector comprises an organic film layer, a conductive layer arranged on at least one side of the organic film layer, and a conductive particle layer arranged between the organic film layer and the conductive layer. According to the present invention, the consistency and the uniformity of the conductive layer on the current collector are improved so as to reduce the internal resistance of the battery, in addition, the generation of burrs or metal particles at the slitting edge during the pole piece slitting process is avoided, and the safety performance of the battery is improved.

Description

Technical Field

[0001] The present application relates to the technical field of batteries, and particularly relates to a current collector, a preparation method thereof, a pole piece, a preparation method thereof, a battery, and an electrical device. Background Art

[0002] Electrochemical devices, such as lithium-ion secondary batteries, have high charge and discharge performance and are environmentally friendly, and are widely used in electric vehicles and consumer electronic products. The current collector is an important component in the electrochemical device, which not only provides support for the active material layer, but also collects the current generated by the active material layer for external output. Therefore, the current collector has an important influence on the performance of the electrode pole piece and the electrochemical device. Summary of the Invention

[0003] The present application is made in view of the above problems, and its purpose is to provide a current collector, a preparation method thereof, a pole piece, a preparation method thereof, a battery, and an electrical device, aiming to improve the consistency and uniformity of the conductive layer on the current collector, thereby reducing the internal resistance of the battery.

[0004] To achieve the above object, in a first aspect, the present application provides a current collector, including an organic film layer, a conductive layer provided on at least one side of the organic film layer, and a conductive particle layer provided between the organic film layer and the conductive layer.

[0005] In the technical solution of the present application, the conductive particle layer provided between the organic film layer and the conductive layer provides growth sites for the subsequent conductive layer, thereby enabling the improvement of the consistency and uniformity of the conductive layer, further reducing the internal resistance of the battery, and improving the conductive performance of the battery.

[0006] In any embodiment, the material of the organic film layer includes at least one of polyethylene terephthalate, polyvinylidene fluoride, polypropylene, polyethylene, polyvinyl chloride, polycarbonate, polyimide, and polyamideimide. The strength and toughness of the above materials are beneficial to providing good support.

[0007] In any embodiment, the organic film layer satisfies at least one of the following conditions:

[0008] (1) The porosity of the organic film layer is 0.1-3%;

[0009] (2) The pore diameter of the organic film layer is 0.001-10 μm;

[0010] (3) The thickness of the organic film layer is 1-20 μm;

[0011] (4) The tensile strength of the organic film layer is greater than 50 Mpa.

[0012] When the porosity, pore size, thickness, and tensile strength of the organic film layer are within the above-mentioned suitable ranges, the organic film layer has appropriate strength and toughness, which is beneficial to providing good support for the subsequent conductive particle layer and conductive layer.

[0013] In any implementation manner, the conductive particles in the conductive particle layer include at least one of conductive nanoparticles, conductive nanowires, and conductive nanotubes. The conductive particles with the above-mentioned nanostructures are beneficial to providing growth sites for the subsequent conductive layer, and the material of the conductive particles in the conductive particle layer includes at least one of conductive carbon materials, copper, aluminum, and silver. The above materials have wide sources and low costs.

[0014] In any implementation manner, the thickness of the conductive particle layer is 0.001 - 5 μm. When the thickness of the conductive particle layer is within this suitable range, it is beneficial to improve the uniformity and consistency of the subsequent conductive layer.

[0015] In any implementation manner, the material of the conductive layer includes at least one of copper, aluminum, nickel, titanium, and silver. The above materials have good electrical conductivity.

[0016] In any implementation manner, the thickness of the conductive layer is 0.1 - 50 μm. When the thickness of the conductive layer is within a suitable range, it can be beneficial to achieve good electrical conductivity of the battery.

[0017] In a second aspect, the present application provides a method for preparing a current collector, including the following steps: providing an organic film layer; disposing conductive particles on at least one surface of the organic film layer to obtain a conductive particle layer; and providing a conductive layer on the conductive particle layer to obtain a current collector.

[0018] This preparation method is simple and easy to industrialize.

[0019] In any implementation manner, the step of providing an organic film layer includes: providing an organic film layer; and performing an activation treatment on at least one surface of the organic film layer. The activation treatment is beneficial to increasing the wettability and adhesiveness of the organic film layer, thereby facilitating the formation of the conductive particle layer.

[0020] In any implementation manner, the activation treatment includes plasma activation or surface oxidation treatment. The above activation treatment can form functional groups such as hydroxyl groups, carboxyl groups, and nitro groups on the surface of the organic film layer or dope the surface of the organic film layer, thereby being beneficial to increasing the wettability and adhesiveness of the organic film layer, and thus being beneficial to the formation of the conductive particle layer.

[0021] In any embodiment, the step of disposing the conductive particles on at least one surface of the organic film layer to obtain a conductive particle layer includes: disposing the conductive particles on at least one surface of the organic film layer by spraying or vapor deposition to obtain a conductive particle layer. Adopting the method of spraying or vapor deposition is beneficial to the uniform coating of the conductive particles.

[0022] In any embodiment, the mass ratio of the conductive particles in the slurry is 1% - 80%. When the mass ratio of the conductive particles is within this appropriate range, it is beneficial for the subsequent conductive layer to be more uniform.

[0023] In any embodiment, the slurry used for spraying includes conductive particles, a polymer, and a solvent. Among them, the mass ratio of the conductive particles in the slurry is 1% - 80%; the mass ratio of the polymer in the slurry is 10% - 80%. Using raw materials with appropriate ratios during the spraying process is beneficial to the uniform dispersion of the conductive particles, and thus beneficial to the uniform coating of the conductive particles.

[0024] In any embodiment, the polymer includes at least one of polyacrylic acid, polyvinyl acetate, styrene-butadiene rubber, and polyvinyl alcohol. Using a suitable polymer in the slurry is beneficial to the uniform dispersion of the conductive particles, and thus beneficial to the uniform coating of the conductive particles.

[0025] In any embodiment, the conductive particles in the conductive particle layer include at least one of conductive nanoparticles, conductive nanowires, and conductive nanotubes. The material of the conductive particles in the conductive particle layer includes conductive carbon materials, copper, aluminum, and silver. The above materials have wide sources and low costs.

[0026] In any embodiment, the step of disposing a conductive layer on the conductive particle layer to obtain a current collector includes: depositing a conductive layer on the conductive particle layer by electroplating, vapor deposition, evaporation, or magnetron sputtering to obtain a current collector. Adopting the above suitable method to deposit the conductive layer is beneficial to obtaining a conductive layer with good uniformity.

[0027] In a third aspect, the present application provides a current collector, including the current collector of the first aspect or the current collector prepared by the preparation method of the second aspect.

[0028] In order to avoid the generation of burrs or metal particles at the slitting edge during the slitting process of the current collector and improve the safety performance of the battery. In a fourth aspect, the present application provides a method for preparing a current collector, including the following steps: providing an organic film layer, alternately arranging a to-be-covered area and a blank area on at least one side of the organic film layer; disposing a conductive metal on the to-be-covered area; coating an active material on at least the conductive metal, and the active material includes a positive electrode active material or a negative electrode active material; performing slitting at the blank area to obtain a current collector.

[0029] Thus, when slitting the pole piece, slitting at the blank area will not cut the conductive metal disposed on the organic film layer, but only cut the organic film layer, avoiding the edge burrs or metal particles generated by cutting the conductive metal and improving the battery safety performance.

[0030] In any implementation manner, the width of the blank area is 0.1 - 10 mm; since the thickness of the slitting knife is usually less than 0.1 mm, the width of the blank area within this appropriate range is conducive to the slitting knife cutting only the organic film layer without cutting the conductive metal disposed on the organic film layer; optionally, the width of the blank area is 0.1 - 5 mm. Within this range, while being conducive to the slitting knife cutting only the organic film layer without cutting the conductive metal disposed on the organic film layer, it is also conducive to cost reduction.

[0031] In any implementation manner, the step of providing an organic film layer and alternately arranging a to-be-covered area and a blank area on at least one side of the organic film layer includes: providing an organic film layer; performing an activation treatment on at least one surface of the organic film layer; and alternately arranging the to-be-covered area and the blank area on the surface of the organic film layer after the activation treatment is completed. The activation treatment is conducive to increasing the wettability and adhesiveness of the organic film layer, thereby facilitating the formation of a conductive particle layer.

[0032] In any implementation manner, the activation treatment includes plasma activation or surface oxidation treatment. The above activation treatment can form functional groups such as hydroxyl, carboxyl, and nitro groups on the surface of the organic film layer, thereby being conducive to increasing the wettability and adhesiveness of the organic film layer and facilitating the formation of a conductive particle layer.

[0033] In any implementation manner, the step of disposing the conductive metal on the to-be-covered area includes: disposing conductive particles on the to-be-covered area to obtain a conductive particle layer; and disposing a conductive layer on the conductive particle layer in the to-be-covered area. Thus, the conductive particle layer disposed between the organic film layer and the conductive layer can provide uniform growth sites for the subsequent conductive layer, thereby improving the consistency and uniformity of the conductive layer, further reducing the battery internal resistance, and improving the battery conductive performance.

[0034] In any implementation manner, the step of disposing the conductive particles on the to-be-covered area to obtain a conductive particle layer includes: shielding the blank area with a barrier medium, and disposing the conductive particles on the to-be-covered area by spraying or vapor deposition to obtain a conductive particle layer formed on the to-be-covered area. Using the spraying or vapor deposition method is conducive to the uniform coating of the conductive particles.

[0035] In any embodiment, the slurry used for spraying comprises conductive particles, a polymer, and a solvent. Among them, the mass ratio of the conductive particles in the slurry is 1% to 80%; the mass ratio of the polymer in the slurry is 10% to 80%. The raw material ratio in the slurry used for spraying is within a suitable range, which is beneficial to the subsequent more uniform conductive layer.

[0036] In any embodiment, the polymer comprises at least one of polyacrylic acid, polyvinyl acetate, styrene-butadiene rubber, and polyvinyl alcohol. Using a suitable polymer in the slurry is beneficial to the uniform dispersion of the conductive particles, and thus beneficial to the uniform coating of the conductive particles.

[0037] In any embodiment, the conductive particles comprise at least one of conductive nanoparticles, conductive nanowires, and conductive nanotubes; the conductive particles with the above nanostructures are beneficial to providing growth sites for the subsequent conductive layer. The material of the conductive particles in the conductive particle layer comprises at least one of conductive carbon materials, copper, aluminum, and silver. The above materials are widely sourced and low in cost.

[0038] In any embodiment, the thickness of the conductive particle layer is 0.001 to 5 μm. When the thickness of the conductive particle layer is within this suitable range, it is beneficial to improve the uniformity and consistency of the subsequent conductive layer.

[0039] In any embodiment, the step of forming a conductive layer on the conductive particle layer in the area to be covered comprises: depositing a conductive metal on the conductive particle layer; removing the barrier medium to obtain the conductive layer. After depositing the conductive layer and then removing the barrier medium, the area blocked by the barrier medium is the blank area formed only by the organic film layer.

[0040] In any embodiment, the material of the conductive layer comprises at least one of copper, aluminum, nickel, titanium, and silver. The above materials have good electrical conductivity.

[0041] In any embodiment, the thickness of the conductive layer is 0.1 to 50 μm. When the thickness of the conductive layer is within a suitable range, it can be beneficial to achieve good electrical conductivity of the battery.

[0042] In any embodiment, the step of depositing a conductive metal on the conductive particle layer comprises: depositing a conductive metal on the conductive particle layer by means of electroplating, chemical vapor deposition, evaporation, or magnetron sputtering. Using a suitable deposition method is beneficial to making the deposited conductive metal more uniform and having better consistency.

[0043] In any embodiment, the barrier medium comprises an insulating tape. Thus, the barrier medium is easy to remove after spraying the conductive particle layer and depositing the conductive layer.

[0044] Fifth aspect, the present application provides a pole piece prepared by the preparation method according to the fourth aspect.

[0045] In any embodiment, the edge of at least one side of the organic film layer extends beyond the edge of the corresponding side of the conductive layer by 0.05 - 5 mm.

[0046] Sixth aspect, the present application provides a battery, including the pole piece according to the third aspect, or including the pole piece prepared by the preparation method according to the fourth aspect, or including the pole piece according to the fifth aspect.

[0047] Seventh aspect, the present application provides an electrical device, including the battery according to the sixth aspect. Description of the Drawings

[0048] Figure 1 is a cross-sectional view of a current collector in an embodiment of the present application;

[0049] Figure 2 is a top view of a current collector in an embodiment of the present application;

[0050] Figure 3 is a cross-sectional view of a coated pole piece before and after slitting in an embodiment of the present application;

[0051] Figure 4 is a top view of a die-cut pole piece before and after slitting in an embodiment of the present application;

[0052] Figure 5 is a schematic diagram of a secondary battery in an embodiment of the present application;

[0053] Figure 6 is Figure 5 the exploded view of the secondary battery shown in an embodiment of the present application;

[0054] Figure 7 is a schematic diagram of a battery module in an embodiment of the present application;

[0055] Figure 8 is a schematic diagram of a battery pack in an embodiment of the present application;

[0056] Figure 9 is Figure 8 the exploded view of the battery pack shown in an embodiment of the present application;

[0057] Figure 10 is a schematic diagram of an electrical device using the secondary battery as a power source in an embodiment of the present application.

[0058] Description of the Reference Numerals:

[0059] 1 Battery pack; 2 Upper box body; 3 Lower box body; 4 Battery module; 5 Secondary battery; 51 Housing; 52 Electrode assembly; 521 Battery cell; 5211 Bare battery cell, 5212 Buffer pad, 5212-1 Adhesive layer, 5212-2 Heat insulation layer, 5212-3 Sustained release layer, 5212-4 Anti-puncture layer, 53 Top cover assembly, 6 Current collector; 61 Organic film layer; 62 Conductive particle layer; 63 Conductive layer; 64 Blank area; d Width of the blank area; 7 Electrode tab. Detailed implementation manners

[0060] Hereinafter, the current collector of the present application, the preparation method thereof, the electrode tab, the preparation method thereof, the battery, and the implementation manners of the electrical device are specifically disclosed. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually identical structures are omitted. This is to prevent the following descriptions from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following descriptions are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0061] The "range" disclosed in the present application is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a specific range. The range defined in this way can include or exclude the end values and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, ranges of 60-110 and 80-120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In the present application, unless otherwise specified, the numerical range "a-b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been fully listed herein, and "0-5" is only an abbreviated representation of these numerical combinations. Additionally, when stating that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0062] If there is no special instruction, all the implementation manners and optional implementation manners of the present application can be combined with each other to form a new technical solution.

[0063] If there is no special instruction, all the technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

[0064] Unless otherwise specified, all steps of this application can be carried out sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) carried out sequentially, or may also include steps (b) and (a) carried out sequentially. For example, when it is mentioned that the method may further include step (c), it means that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or may also include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0065] Electrochemical devices, such as lithium-ion secondary batteries, have high charge and discharge performance and are environmentally friendly, and are widely used in electric vehicles and consumer electronic products. The current collector is an important component in an electrochemical device, which not only provides support for the active material layer but also collects the current generated by the active material layer for external output. Therefore, the current collector has an important impact on the performance of the electrode sheet and the electrochemical device.

[0066] In view of this, the embodiments of this application provide a current collector and a preparation method thereof, an electrode sheet and a preparation method thereof, a battery, and an electrical device.

[0067] In a first aspect, the embodiments of this application provide a current collector 6, see Figure 1 , including an organic film layer 61, a conductive layer 63 provided on at least one side of the organic film layer 61, and a conductive particle layer 62 provided between the organic film layer 61 and the conductive layer 63.

[0068] Herein, the "conductive particle layer" means that the layer contains conductive particles.

[0069] In the technical solution of this application, the conductive particle layer 62 provided between the organic film layer 61 and the conductive layer 63 provides uniform growth sites for the subsequent conductive layer 63, thereby enabling the improvement of the consistency and uniformity of the conductive layer 63, further reducing the internal resistance of the battery, and improving the conductive performance of the battery.

[0070] In some embodiments, the material of the organic film layer 61 includes at least one of polyethylene terephthalate, polyvinylidene fluoride, polypropylene, polyethylene, polyvinyl chloride, polycarbonate, polyimide, and polyamideimide. The strength and toughness of the above materials are beneficial for providing good support.

[0071] In some embodiments, the organic film layer 61 satisfies at least one of the following conditions: (1) the porosity of the organic film layer 61 is 0.1% to 3%; (2) the pore size of the organic film layer 61 is 0.001 to 10 μm; (3) the thickness of the organic film layer 61 is 1 to 20 μm; (4) the tensile strength of the organic film layer 61 is greater than 50 Mpa. The porosity, pore size, thickness, and tensile strength of the organic film layer 61 are within the above suitable ranges, enabling the organic film layer 61 to have appropriate strength and toughness, which is beneficial for providing good support for the subsequent conductive particle layer 62 and conductive layer 63. Exemplarily, the porosity of the organic film layer 61 can be 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3% or any value between the above values. The pore size of the organic film layer 61 can be 0.005 μm, 0.01 μm, 0.05 μm, 0.1 μm, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm or any value between the above values. The thickness of the organic film layer 61 can be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm or any value between the above values. The tensile strength of the organic film layer 61 can be 60 Mpa, 80 Mpa, 100 Mpa, 150 Mpa, 200 Mpa, etc.

[0072] In some embodiments, the conductive particles in the conductive particle layer 62 include at least one of conductive nanoparticles, conductive nanowires, and conductive nanotubes. The conductive particles with the above nanostructures are beneficial for providing growth sites for the subsequent conductive layer 63. The material of the conductive particles in the conductive particle layer 62 includes at least one of conductive carbon materials, copper, aluminum, and silver. The above materials are widely sourced and low in cost.

[0073] It should be noted that, in some embodiments, the particle size of the conductive nanoparticles can be 1 to 1000 nm; the diameter of the conductive nanowires can be 1 to 1000 nm; the diameter of the conductive nanotubes can be 1 to 1000 nm. When the particle size or diameter of the conductive nanoparticles is within a suitable range, it is beneficial to provide growth sites for the subsequent conductive layer 63. Exemplarily, the particle size of the conductive nanoparticles can be 1 nm, 10 nm, 50 nm, 100 nm, 500 nm, 1000 nm, or any value between the above values. The diameter of the conductive nanowires can be 1 nm, 10 nm, 50 nm, 100 nm, 500 nm, 1000 nm, or any value between the above values. The diameter of the conductive nanotubes can be 1 nm, 10 nm, 50 nm, 100 nm, 500 nm, 1000 nm, or any value between the above values.

[0074] In some embodiments, the thickness of the conductive particle layer 62 is 0.001 to 5 μm. When the thickness of the conductive particle layer 62 is within this suitable range, it is beneficial to improve the uniformity and consistency of the subsequent conductive layer 63. Exemplarily, the thickness of the conductive particle layer 62 can be 0.001 μm, 0.002 μm, 0.003 μm, 0.004 μm, 0.005 μm, 0.006 μm, 0.007 μm, 0.008 μm, 0.009 μm, 0.01 μm, 0.02 μm, 0.03 μm, 0.04 μm, 0.05 μm, 0.06 μm, 0.07 μm, 0.08 μm, 0.09 μm, 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, 2 μm, 3 μm, 4 μm, 5 μm, or any value between the above values.

[0075] In some embodiments, the material of the conductive layer 63 includes at least one of copper, aluminum, nickel, titanium, and silver. The above materials have good electrical conductivity.

[0076] In some embodiments, the thickness of the conductive layer 63 is 0.1 to 50 μm. When the thickness of the conductive layer 63 is within a suitable range, it can be beneficial to achieve good electrical conductivity of the battery. Exemplarily, the thickness of the conductive layer 63 can be 0.1 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, or any value between the above values.

[0077] In a second aspect, the present application provides a method for preparing a current collector 6, including the following steps: providing an organic film layer 61; disposing conductive particles on at least one surface of the organic film layer 61 to obtain a conductive particle layer 62; and disposing a conductive layer 63 on the conductive particle layer 62 to obtain the current collector 6.

[0078] The preparation method is simple and easy to industrialize.

[0079] In some embodiments, the step of providing an organic film layer 61 includes: providing an organic film layer 61; performing an activation treatment on at least one surface of the organic film layer 61. The activation treatment is beneficial to increasing the wettability and adhesiveness of the organic film layer 61, thereby facilitating the formation of the conductive particle layer 62.

[0080] In some embodiments, the activation treatment includes plasma activation or surface oxidation treatment. It should be noted that plasma activation refers to plasma surface treatment, which means the physical or chemical action process of using the plasma of non-polymeric inorganic gases such as Ar, N2, O2, H2, etc. on the material surface to form new functional groups, etc. Participating in the surface reaction are excited state molecules, free radicals and ions, and also include the action of plasma radiation ultraviolet light. Surface oxidation treatment refers to using an oxidant solution (such as a solution of potassium permanganate) to oxidize the surface of the organic film layer to generate polar groups such as carbonyl and carboxyl groups, thereby increasing the surface free energy of the film surface and enhancing the wetting ability and adhesion ability of the film surface. Here, the oxidant solution used in the surface oxidation treatment includes an oxidizing acid solution.

[0081] The above activation treatment can form functional groups such as hydroxyl, carboxyl, nitro, etc. on the surface of the organic film layer 61, thereby being beneficial to increasing the wettability and adhesiveness of the organic film layer, and thus being beneficial to the formation of the conductive particle layer.

[0082] In some embodiments, the step of disposing conductive particles on at least one surface of the organic film layer 61 to obtain the conductive particle layer 62 includes: disposing the conductive particles on at least one surface of the organic film layer 61 by spraying or vapor deposition to obtain the conductive particle layer 62. Adopting the method of spraying or vapor deposition is beneficial to the uniform coating of the conductive particles.

[0083] In some embodiments, the slurry used for spraying includes conductive particles, polymers, and solvents. Among them, the mass ratio of the conductive particles in the slurry is 1% - 80%. When the mass ratio of the conductive particles is within this appropriate range, it is beneficial for the subsequent conductive layer to be more uniform. The mass ratio of the conductive particles in the slurry can be 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80% or any value between the above values. The mass ratio of the polymers in the slurry is 10% - 80%. When the mass ratio of the polymers is within this appropriate range, it is beneficial for the subsequent conductive layer to be more uniform. The mass ratio of the polymers in the slurry can be 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80% or any value between the above values.

[0084] In some embodiments, the polymers include at least one of polyacrylic acid, polyvinyl acetate, styrene-butadiene rubber, and polyvinyl alcohol. Using the above-mentioned appropriate polymers in the slurry is beneficial for the uniform dispersion of the conductive particles, and thus beneficial for the uniform coating of the conductive particles.

[0085] It should be noted that when the conductive particles are disposed on at least one surface of the organic film layer 61 by spraying, the solvent can be water. After spraying the slurry, the solvent can be removed by drying. The drying temperature can be 60 - 120°C, and the drying time can be 2 - 4h. Under this appropriate drying temperature and drying time, it is beneficial for the volatilization of the solvent and does not damage the structure of the conductive particles. Exemplarily, the drying temperature can be 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C or any value between the above values, and the drying time can be 2h, 2.5h, 3h, 3.5h, 4h or any value between the above values.

[0086] In some embodiments, the conductive particles in the conductive particle layer 62 include at least one of conductive nanoparticles, conductive nanowires, and conductive nanotubes. The conductive particles with the above-mentioned nanostructures are beneficial for providing growth sites for the subsequent conductive layer 63. The material of the conductive particles in the conductive particle layer 62 includes at least one of conductive carbon materials, copper, aluminum, and silver. The above materials are widely sourced and low in cost.

[0087] In some embodiments, the step of forming the current collector 6 by disposing the conductive layer 63 on the conductive particle layer 62 includes: depositing the conductive layer 63 on the conductive particle layer 62 by electroplating, chemical vapor deposition, evaporation, or magnetron sputtering to obtain the current collector 6. Depositing the conductive layer 63 by the above-mentioned appropriate method is beneficial for obtaining a conductive layer 63 with good uniformity.

[0088] In a third aspect, an embodiment of the present application provides a pole piece, including the current collector of the first aspect or the current collector prepared by the preparation method according to the second aspect.

[0089] In a fourth aspect, an embodiment of the present application provides a method for preparing a pole piece, including the following steps: providing an organic film layer 61, alternately arranging a to-be-covered area and a blank area 64 on at least one side of the organic film layer 61; disposing a conductive metal in the to-be-covered area; coating an active material on at least the conductive metal, where the active material includes a positive electrode active material or a negative electrode active material; and performing slitting at the blank area 64 to obtain a pole piece 7.

[0090] It should be noted that usually, the pole piece completed after coating and rolling is very wide. Therefore, the pole piece needs to be slit into multiple strips. The slitting of the pole piece refers to slitting the rolled pole piece according to the battery specifications. The slitting is performed using a circular slitting knife mounted on the knife shaft of a slitting machine, and the slitting principle of rolling shear is utilized. Burrs and metal particles may be generated during the slitting process. In particular, metal burrs are more harmful to lithium batteries. Larger metal burrs and metal particles may pierce the separator, resulting in short circuit between the anode and the cathode, and risks of high-voltage breakdown and even thermal runaway. Metal particles are deposited on the anode surface during the charge and discharge process to form dendrites, which also pose a risk of piercing the separator and causing thermal runaway.

[0091] Therefore, in the technical solution of the present application, referring to Figures 2 - 4 , when the pole piece 7 is slit, the slitting is performed at the blank area, and the blank area is an area only including the organic film layer 61, without cutting the conductive metal disposed on the organic film layer 61, avoiding the edge burrs or metal particles generated by cutting the conductive metal, and improving the battery safety performance.

[0092] In some embodiments, the width d of the blank area is 0.1 - 10 mm. Since the thickness of the slitting knife is usually less than 0.1 mm, when the width d of the blank area is within this suitable range, it is beneficial for the slitting knife to only cut the organic film layer without cutting the conductive metal disposed on the organic film layer; the width of the blank area can be 0.1 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm, 6.5 mm, 7 mm, 7.5 mm, 8 mm, 8.5 mm, 9 mm, 9.5 mm, 10 mm or any value between the above values. Optionally, the width of the blank area is 0.1 - 5 mm. Within this range, while being beneficial for the slitting knife to only cut the organic film layer without cutting the conductive metal disposed on the organic film layer, it is beneficial to reduce costs.

[0093] It should be noted that, for the convenience of subsequent processes such as the welding of the tab, the distance between adjacent blank areas can be set as follows: the distance between adjacent blank areas = 2 × the width of the electrode sheet die area + 2 × the height of the tab. The width of the electrode sheet die area can refer to the area where the positive active material is coated.

[0094] In some embodiments, providing an organic film layer 61 and alternately arranging the areas to be covered and the blank areas on at least one side of the organic film layer 61 includes: providing an organic film layer 61; performing an activation treatment on at least one side surface of the organic film layer 61; and alternately arranging the areas to be covered and the blank areas on the surface of the organic film layer 61 after the activation treatment is completed. The activation treatment is beneficial to increasing the wettability and adhesiveness of the organic film layer 61, thereby facilitating the formation of the conductive particle layer 62.

[0095] In some embodiments, the activation treatment includes plasma activation or surface oxidation treatment. The above activation treatment can form functional groups such as hydroxyl groups, carboxyl groups, and nitro groups on the surface of the organic film layer or dope the surface of the organic film layer, thereby being beneficial to increasing the wettability and adhesiveness of the organic film layer, and thus being beneficial to the formation of the conductive particle layer.

[0096] In some embodiments, the step of disposing the conductive metal in the area to be covered includes: disposing conductive particles in the area to be covered to obtain a conductive particle layer 62; and disposing a conductive layer 63 on the conductive particle layer 62 in the area to be covered. Thus, the conductive particle layer 62 disposed between the organic film layer 61 and the conductive layer 63 can provide uniform growth sites for the subsequent conductive layer 63, thereby being able to improve the consistency and uniformity of the conductive layer 63, further reducing the internal resistance of the battery, and improving the conductive performance of the battery.

[0097] In some embodiments, the step of disposing conductive particles in the area to be covered to obtain a conductive particle layer 62 includes: shielding the blank area with a barrier medium, and disposing the conductive particles on the area to be covered by spraying or vapor deposition to obtain a conductive particle layer 62 formed on the area to be covered. The method of spraying or vapor deposition is beneficial to the uniform coating of the conductive particles.

[0098] In some embodiments, the slurry used for spraying includes conductive particles, polymers, and solvents. Among them, the mass ratio of the conductive particles in the slurry is 1% - 80%. When the mass ratio of the conductive particles is within this appropriate range, it is beneficial for the subsequent conductive layer to be more uniform. The mass ratio of the conductive particles in the slurry can be 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80% or any value between the above values. The mass ratio of the polymers in the slurry is 10% - 80%. When the mass ratio of the polymers is within this appropriate range, it is beneficial for the subsequent conductive layer to be more uniform. The mass ratio of the polymers in the slurry can be 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80% or any value between the above values.

[0099] In some embodiments, the polymer includes at least one of polyacrylic acid, polyvinyl acetate, styrene-butadiene rubber, and polyvinyl alcohol. Using the above-mentioned appropriate polymers in the slurry is beneficial for the uniform dispersion of the conductive particles, and thus beneficial for the uniform coating of the conductive particles.

[0100] In some embodiments, the conductive particles in the conductive particle layer 62 include at least one of conductive nanoparticles, conductive nanowires, and conductive nanotubes. The conductive particles with the above-mentioned nanostructures are beneficial for providing growth sites for the subsequent conductive layer 63. The material of the conductive particles in the conductive particle layer 62 includes at least one of conductive carbon materials, copper, aluminum, and silver. The above materials have wide sources and low costs.

[0101] In some embodiments, the thickness of the conductive particle layer 62 is 0.001 - 5 μm. When the thickness of the conductive particle layer 62 is within this appropriate range, it is beneficial to improve the uniformity and consistency of the subsequent conductive layer 63. Exemplarily, the thickness of the conductive particle layer 62 can be 0.001 μm, 0.002 μm, 0.003 μm, 0.004 μm, 0.005 μm, 0.006 μm, 0.007 μm, 0.008 μm, 0.009 μm, 0.01 μm, 0.02 μm, 0.03 μm, 0.04 μm, 0.05 μm, 0.06 μm, 0.07 μm, 0.08 μm, 0.09 μm, 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, 2 μm, 3 μm, 4 μm, 5 μm or any value between the above values.

[0102] In some embodiments, the steps of disposing the conductive layer 63 on the conductive particle layer 62 in the to-be-covered area include: depositing a conductive metal on the conductive particle layer 62; and removing the barrier medium to obtain the conductive layer 63. After depositing the conductive layer 63, the barrier medium is removed, and the area blocked by the barrier medium is the blank area formed only by the organic film layer 61.

[0103] In some embodiments, the material of the conductive layer 63 includes at least one of copper, aluminum, nickel, titanium, and silver. The above materials have good electrical conductivity.

[0104] In some embodiments, the thickness of the conductive layer 63 is 0.1 - 50 μm. When the thickness of the conductive layer 63 is within a suitable range, it is beneficial to achieve good electrical conductivity of the battery. Exemplarily, the thickness of the conductive layer 63 can be 0.1 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm or any value between the above values.

[0105] In some embodiments, the steps of depositing a conductive metal on the conductive particle layer 62 include: depositing a conductive metal on the conductive particle layer 62 by means of electroplating, chemical vapor deposition, evaporation, or magnetron sputtering. Using a suitable deposition method is beneficial to make the deposited conductive metal more uniform and have better consistency.

[0106] In some embodiments, the barrier medium includes an insulating tape. Thus, the barrier medium is easy to remove after spraying the conductive particle layer 62 and depositing the conductive layer 63.

[0107] In a fifth aspect, the present application provides an electrode sheet prepared by the preparation method according to the fourth aspect.

[0108] In any implementation manner, the edge of at least one side of the organic film layer 61 extends beyond the edge of the corresponding side of the conductive layer by 0.05 - 5 mm. Since the slitting is performed in the blank area, and the blank area is the area only containing the organic film layer without cutting the conductive metal disposed on the organic film layer, after one cutting, the edge of at least one side of the organic film layer extends beyond the edge of the corresponding side of the conductive layer by 0.05 - 5 mm. It should be noted that the part where the edge of the organic film layer extends beyond the conductive layer can be removed by secondary cutting according to actual needs.

[0109] In a sixth aspect, the present application provides a battery, including the electrode sheet according to the third aspect, or including the electrode sheet prepared by the preparation method according to the fourth aspect, or including the electrode sheet according to the fifth aspect.

[0110] In any implementation manner, the battery is a primary battery or a secondary battery.

[0111] Under normal circumstances, a secondary battery includes a positive electrode plate, a negative electrode plate, an electrolyte, and a separator. During the charging and discharging process of the battery, active ions are embedded and extracted back and forth between the positive electrode plate and the negative electrode plate. The electrolyte plays a role in conducting ions between the positive electrode plate and the negative electrode plate. The separator is disposed between the positive electrode plate and the negative electrode plate, mainly to prevent short circuit between the positive and negative electrodes, and at the same time allows ions to pass through.

[0112] The positive electrode plate includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, and the positive electrode film layer includes a positive electrode active material.

[0113] As an example, the positive electrode current collector has two surfaces opposite to each other in its own thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.

[0114] In some embodiments, the positive electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, aluminum foil can be used. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0115] In some embodiments, when the secondary battery is a lithium-ion battery, the positive electrode active material can be a positive electrode active material known in the art for lithium-ion batteries. As an example, the positive electrode active material can include at least one of the following materials: lithium-containing phosphate with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials can also be used. These positive electrode active materials can be used alone or in combination of two or more. Among them, examples of lithium transition metal oxides can include but are not limited to lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3Mn 1 / 3 O2 (which can also be abbreviated as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (which can also be abbreviated as NCM 523 ), LiNi 0.5 Co0.25 Mn 0.25 O2 (which can also be abbreviated as NCM 211 )、LiNi 0.6 Co 0.2 Mn 0.2 O2 (which can also be abbreviated as NCM 622 )、LiNi 0.8 Co 0.1 Mn 0.1 O2 (which can also be abbreviated as NCM 811 )、lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2), and at least one of its modified compounds, etc. Examples of olivine-structured lithium-containing phosphates may include but are not limited to lithium iron phosphate (such as LiFePO4 (which can also be abbreviated as LFP)), composites of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), composites of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and at least one of composites of lithium manganese iron phosphate and carbon.

[0116] In some embodiments, the positive electrode film layer may further optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0117] In some embodiments, the positive electrode film layer may further optionally include a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0118] In some embodiments, the positive electrode plate can be prepared by the following method: dispersing the above components for preparing the positive electrode plate, such as positive electrode active material, conductive agent, binder, and any other components, in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on the positive electrode current collector, and after processes such as drying and cold pressing, the positive electrode plate can be obtained.

[0119] The negative electrode plate includes a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector, and the negative electrode film layer includes a negative electrode active material.

[0120] As an example, the negative electrode current collector has two surfaces opposite to each other in its own thickness direction, and the negative electrode film layer is provided on either one or both of the two opposite surfaces of the negative electrode current collector.

[0121] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, copper foil may be used. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0122] In some embodiments, the negative electrode active material may be a negative electrode active material for batteries well-known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other conventional materials that can be used as the negative electrode active material of the battery may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0123] In some embodiments, the negative electrode film layer may also optionally include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0124] In some embodiments, the negative electrode film layer may also optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0125] In some embodiments, the negative electrode film layer may also optionally include other additives, such as thickeners (such as sodium carboxymethyl cellulose (CMC-Na)), etc.

[0126] In some embodiments, the negative electrode plate can be prepared by the following method: dispersing the above components for preparing the negative electrode plate, such as the negative electrode active material, conductive agent, binder, and any other components, in a solvent (such as deionized water) to form a negative electrode slurry; coating the negative electrode slurry on the negative electrode current collector, and after processes such as drying and cold pressing, the negative electrode plate can be obtained.

[0127] The electrolyte plays a role in conducting ions between the positive electrode plate and the negative electrode plate. There is no specific limitation on the type of electrolyte in this application, and it can be selected according to requirements. For example, the electrolyte can be liquid, gel-like, or all-solid state.

[0128] In some embodiments, the electrolyte uses an electrolytic solution. The electrolytic solution includes an electrolyte salt and a solvent.

[0129] In some embodiments, the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluoro bis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate.

[0130] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0131] In some embodiments, the electrolytic solution may also optionally include additives. For example, the additives can include negative electrode film-forming additives, positive electrode film-forming additives, and can also include additives that can improve certain battery performances, such as additives for improving the overcharge performance of the battery, additives for improving the high-temperature or low-temperature performance of the battery, etc.

[0132] In some embodiments, the material of the separator base film can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator base film can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator base film is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0133] In some embodiments, the positive electrode plate, the negative electrode plate, and the separator can be made into an electrode assembly through a winding process or a stacking process.

[0134] In some embodiments, the secondary battery can include an outer package. The outer package can be used to encapsulate the above-mentioned electrode assembly and electrolyte.

[0135] In some embodiments, the outer package of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package of the secondary battery can also be a soft package, such as a pouch-type soft package. The material of the soft package can be plastic. As plastics, polypropylene, polybutylene terephthalate, and polybutylene succinate can be listed, etc.

[0136] The shape of the secondary battery in the present application is not particularly limited, and it can be cylindrical, square, or any other shape. For example, Figure 5 Figure 5 shows a secondary battery 5 having a square structure as an example.

[0137] In some embodiments, referring to Figure 6 , the outer package may include a housing 51 and a cover plate 53. Among them, the housing 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose to form a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity. The positive electrode plate, the negative electrode plate, and the separator may be formed into an electrode assembly 52 through a winding process or a stacking process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and those skilled in the art can select according to specific actual requirements.

[0138] In some embodiments, the secondary batteries can be assembled into a battery module, and the number of secondary batteries included in the battery module may be one or more. The specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0139] Figure 7 Figure 4 shows a battery module 4 as an example. Referring to Figure 7 , in the battery module 4, a plurality of secondary batteries 5 may be arranged in sequence along the length direction of the battery module 4. Of course, they can also be arranged in any other manner. Further, the plurality of secondary batteries 5 can be fixed by fasteners.

[0140] Optionally, the battery module 4 may further include a housing having a receiving space, and a plurality of secondary batteries 5 are received in the receiving space.

[0141] In some embodiments, the above battery module can be further assembled into a battery pack, and the number of battery modules included in the battery pack may be one or more. The specific number can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0142] Figure 8 and Figure 9 Figure 1 shows a battery pack 1 as an example. Referring to Figure 8 and Figure 9 , the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box. The battery box includes an upper box body 2 and a lower box body 3. The upper box body 2 can be covered on the lower box body 3 to form a closed space for receiving the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0143] In a seventh aspect, an embodiment of the present application provides an electrical device, including the battery according to the third aspect of the present application.

[0144] In addition, the present application also provides an electrical device, which includes at least one of a secondary battery, a battery module, or a battery pack provided by the present application. The secondary battery, the battery module, or the battery pack can be used as the power source of the electrical device or as the energy storage unit of the electrical device. The electrical device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc., but is not limited thereto.

[0145] As the electrical device, a secondary battery, a battery module, or a battery pack can be selected according to its usage requirements.

[0146] Figure 10 Take an electrical device as an example. The electrical device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the high power and high energy density requirements of the electrical device for the secondary battery, a battery pack or a battery module can be adopted.

[0147] Another example of the device can be a mobile phone, a tablet computer, a laptop computer, etc. This device usually requires being thin and light, and a secondary battery can be used as the power source.

[0148] Embodiment

[0149] Hereinafter, embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application and should not be construed as a limitation to the present application. For those embodiments where specific technologies or conditions are not indicated, the technologies or conditions described in the literature in the art or according to the product specifications are followed. For the reagents or instruments whose manufacturers are not indicated, they are all conventional products that can be obtained through commercial purchase.

[0150] Embodiment 1

[0151] Preparation of Lithium Secondary Battery

[0152] 1. Preparation of the positive current collector:

[0153] Preparation of the organic film layer: Melt PET monomers at a temperature of 300 °C, extrude and cast the molten PET to form a PET film layer with a thickness of 10 μm, then heat the film layer to 230 °C and stretch it with a deformation of 80% to obtain a PET organic film with a thickness of 8 μm. The porosity is 1%, the pore diameter is 0.008 μm, and the tensile strength in all directions is greater than 50 Mpa.

[0154] Surface activation treatment of the organic film layer: The PET organic film is subjected to N2 plasma treatment at 100 °C, with the chamber pressure less than 10 -4 Mpa and the treatment time is 30 s.

[0155] Preparation of the conductive particle layer: Conductive carbon black nanoparticles, polyacrylic acid and water are mixed to obtain a slurry, such that the mass ratio of conductive carbon black in the slurry is 40%, and the mass ratio of polyacrylic acid in the slurry is 15%. Using the spraying method, a conductive carbon black solution with a thickness of 1 μm is sprayed on the surface of the organic film layer, and dried for 2 h in an environment of 60 °C to obtain a conductive particle layer formed on the surface of the organic film layer.

[0156] Preparation of the conductive layer: The organic film layer provided with the conductive particle layer is placed in a 1M copper sulfate acidic aqueous solution electrolytic cell and connected to the cathode of the electrolytic cell, with high-purity copper as the anode. Under the condition of a current density of 1 mA cm -2 electrodeposition is carried out for 1 h to obtain a copper conductive layer with a thickness of 3 μm.

[0157] 2. Preparation of the electrolyte for the lithium secondary battery

[0158] Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) are mixed in a mass ratio of 30:70 to obtain a mixed solution, and the ether compound prepared in Example 3 is mixed with the mixed solution in a volume ratio of 3:1 to obtain an organic solvent.

[0159] The fully dried electrolyte salt LiPF6 is dissolved in the above organic solvent, and the content of LiPF6 is 12.5% of the total mass of the electrolyte. After mixing evenly, the electrolyte for the lithium secondary battery is obtained.

[0160] 3. Preparation of the secondary battery

[0161] Preparation of the positive electrode plate

[0162] The positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811), conductive agent carbon black (Super P), and binder polyvinylidene fluoride (PVDF) are mixed evenly in an appropriate amount of solvent N-methylpyrrolidone (NMP) in a mass ratio of 96.2:2.7:1.1 to obtain a positive electrode slurry. The positive electrode slurry is coated on the positive electrode current collector prepared above, and through the processes of drying, cold pressing, slitting, and cutting, a positive electrode plate is obtained.

[0163] Preparation of the negative electrode plate

[0164] The artificial graphite as the negative electrode active material, carbon black (Super P) as the conductive agent, styrene-butadiene rubber (SBR) as the binder, and sodium carboxymethyl cellulose (CMC-Na) were mixed evenly in an appropriate amount of deionized water solvent according to the mass ratio of 96.4:0.7:1.8:1.1 to obtain a negative electrode slurry. The negative electrode slurry was coated on a negative electrode current collector copper foil, and through processes such as drying, cold pressing, slitting, and cutting, a negative electrode plate was obtained.

[0165] The separator membrane uses a polyethylene membrane.

[0166] The positive electrode plate, the separator membrane, and the negative electrode plate were stacked in sequence, with the separator membrane placed between the positive and negative electrode plates to play a role in isolation, and then wound to obtain an electrode assembly; the electrode assembly was placed in an outer package, and the above-mentioned electrolyte for the lithium secondary battery was injected into the dried secondary battery, and through processes such as vacuum packaging, standing, formation, and shaping, a secondary battery was obtained.

[0167] The differences between Examples 2 to 16 and Comparative Examples 1-2 of this application and Example 1 lie in the different preparation parameters of the positive electrode current collector. The specific parameters are shown in Table 1.

[0168] Among them, the difference between Example 4 and Example 1 lies in the different preparation of the conductive particle layer in the positive electrode current collector. The specific preparation of the conductive particle layer in Example 4 is as follows: ALD atomic layer deposition was carried out on the surface of the organic film layer. The specific process of ALD atomic layer deposition is: Cu(I)-alginate was used as the copper precursor material, and it entered the deposition reaction chamber at a rate of 1 g / min in a gas-phase pulse flow. The deposition temperature was 80 °C, and the deposition time was 1 h. After the reaction ended, Ar gas was passed to carry out the residual reaction precursors in the cavity, cooled for 30 min, and the deposited film material was taken out to obtain a conductive particle layer formed on the surface of the organic film layer. The conductive particles in the conductive particle layer are copper nanoparticles.

[0169] The difference between Example 10 and Example 1 lies in the different preparation of the conductive layer in the positive electrode current collector. The specific preparation of the conductive layer in Example 10 is as follows: The organic film layer provided with the conductive particle layer was placed in a high-temperature evaporation coating cavity with a vacuum degree lower than 10 -3 Pa as the deposition substrate material. Metal aluminum was placed on a heating table, and metal aluminum was heated by an electron beam to form aluminum vapor. The aluminum vapor diffused to the surface of the base film for deposition to form an aluminum film. The evaporation coating time was 0.5 h, and the thickness of the conductive layer was 3 μm.

[0170] Example 14 is different from Example 1 in the preparation of the organic film layer on the positive current collector. The specific preparation of the organic film layer in Example 14 is as follows: Place polyetherimide particles in a vacuum oven at 150 °C and dry for 5 h until the water content drops below 0.05%. Take the dried PEI, add polyvinylpyrrolidone (PVP) and N,N-dimethylacetamide (DMAc) to obtain a precursor solution. Among them, the mass ratio of polyetherimide in the precursor solution is 25%, and the mass ratio of polyvinylpyrrolidone is 2%. Place the precursor solution in a water bath at 60 °C, heat and stir for 5 h, and perform ultrasonic degassing for 30 min to obtain a homogeneous solution. Using a spraying device, spray the precursor solution on the substrate, control the thickness at 8 μm, immediately spray deionized water after spraying the precursor solution to gel the diaphragm, and perform multiple washes to obtain a PEI-based film.

[0171] Example 15 is different from Example 1 in the preparation of the organic film layer on the positive current collector. The specific preparation of the organic film layer in Example 14 is as follows: Weigh a certain amount of PP resin and load it into an extruder, and heat and melt it at 200 °C. Extrude it through an extrusion die head into a thin sheet with a thickness less than 0.5 mm, and obtain a precursor base film sheet after cooling and pressing by a cold pressing roller. Subsequently, preheat it in a temperature environment of 150 °C, and perform multi-point stretching using the speed difference through several speed-up rollers. The longitudinal stretching multiple is 5 times (the specific stretching multiple is affected by the thickness of the precursor base film. The greater the thickness, the greater the stretching multiple). After longitudinal stretching, the film sheet enters a tenter frame and is transversely stretched 5 times at 150 °C. Then perform stress relaxation at 200 °C to obtain a BOPP-based film with a thickness of 8 μm.

[0172] The test method for the internal resistance of the battery is as follows:

[0173] Take the battery cell to be tested:

[0174] 1) Constant current charging: Charge the battery cell at a charging rate of 0.33C until the cut-off voltage U1.

[0175] 2) Constant voltage charging: Keep charging at voltage U1 until the current reaches 0.05C and cut off.

[0176] 3) Pulse discharge: Discharge at a current of 5C, with a pulse time of 30 ms, and record the voltage U2 after the pulse.

[0177] 4) Calculate the internal resistance using the formula: R = (U1 - U2) / 30.

[0178] Table 1 Parameters and performance data of Examples 1 to 16 and Comparative Examples 1-2

[0179]

[0180] As can be seen from the data in Table 1, for the current collectors of Examples 1-16 of the present application, a conductive particle layer is provided between the organic film layer and the conductive layer, and the internal resistance of the battery is lower than 0.4 mΩ, indicating that the battery has a smaller polarization overpotential and a smaller thermal effect. For the current collector in Comparative Example 1 that only uses an organic film layer and a conductive layer, the internal resistance of the battery is 0.5 mΩ. Although the surface of the organic film layer in Comparative Example 2 was treated to enhance the adhesion between the organic film layer and the conductive layer, the internal resistance of the battery prepared with the current collector in Comparative Example 2 is still higher than 0.4 mΩ.

[0181] As can be seen from Example 1 and Example 16, performing N2 plasma treatment on the organic film layer before setting the conductive particle layer can further reduce the internal resistance of the corresponding battery.

[0182] Example 17

[0183] This example provides a method for preparing a pole piece and a pole piece prepared by this preparation method. The preparation method includes the following steps:

[0184] Preparation of the organic film layer: Melt PET monomers at a temperature of 300 °C, extrude and cast the molten PET to form a PET film layer with a thickness of 10 μm, then heat the film layer to 230 °C and stretch it with a deformation of 80% to obtain a PET organic film with a thickness of 5 μm. The porosity is 1%, the pore diameter is 0.008 μm, and the tensile strength in all directions is greater than 50 Mpa.

[0185] Surface activation treatment of the organic film layer: Perform N2 plasma treatment on the PET organic film at 100 °C, with the chamber pressure less than 10 -4 Mpa and a treatment time of 30 s.

[0186] Alternately set a to-be-covered area and a blank area on the surface of the activated organic film layer, and stick insulating tape to the blank area to block the blank area. In this example, the width of the blank area is 5 mm. The spacing between adjacent blank areas = 2 × the width of the pole piece die area + 2 × the height of the tab.

[0187] Preparation of the conductive particle layer: Mix conductive carbon black nanoparticles, polyacrylic acid, and water to obtain a slurry, and make the mass ratio of conductive carbon black in the slurry 40% and the mass ratio of polyacrylic acid in the slurry 15%. Using the spraying method, spray a conductive carbon black solution with a thickness of 1 μm on the to-be-covered area of the organic film layer surface, and dry it for 2 h in an environment of 60 °C to obtain a conductive particle layer formed on the to-be-covered area of the organic film layer surface.

[0188] Preparation of the conductive layer: Place the organic film layer provided with the conductive particle layer in a 1M copper sulfate acidic aqueous solution electrolytic cell and connect it to the cathode of the electrolytic cell, with high-purity copper as the anode. At a current density of 1 mA cm -2Under the condition of , electroplating was carried out for 1 h, and the thickness of the copper conductive layer obtained was 3 μm.

[0189] Remove the insulating tape.

[0190] Coating and slitting of the electrode sheet: When coating the electrode sheet, the coating die area width = the distance between two adjacent blank areas - 2 × tab height - blank area width. The coating die area is symmetric along the blank area, and the blank area is also coated. When slitting, the electrode sheet is slit along the midline of the blank area, and the edge of the slit edge of the obtained electrode sheet is an organic film layer and does not contact the metal conductive layer. In this embodiment, the edge of at least one side of the organic film layer exceeds the edge of the corresponding side of the metal layer by 2.5 mm.

[0191] The parameters and performances of Examples 18-34 and Comparative Examples 3-4 are shown in Table 2.

[0192] Among them, in Comparative Example 3 and Comparative Example 4, no blank area is provided, and the entire area of the organic film layer is the area to be covered.

[0193] Table 2 Parameters and performance data of Examples 17 to 34 and Comparative Examples 3-4

[0194]

[0195] As can be seen from the content of Table 2, the electrode sheet preparation method adopted in Examples 17-34 of the present application provides an organic film layer, and a to-be-covered area and a blank area are alternately arranged on at least one side of the organic film layer; a conductive metal is disposed in the to-be-covered area; an active material is coated at least on the conductive metal; and slitting is performed at the blank area to obtain an electrode sheet. Thus, when slitting the electrode sheet, slitting is performed at the blank area, and the blank area is an area only containing the organic film layer and will not cut the conductive metal disposed on the organic film layer, and no edge burrs or metal particles will be generated during slitting. In Comparative Examples 3-4, since no blank area is provided and the entire area of the organic film layer is the area to be covered, that is, a metal layer is provided in the entire area of the organic film layer, edge burrs or metal particles will be generated during slitting.

[0196] It should be noted that the present application is not limited to the above embodiments. The above embodiments are only examples, and embodiments having the same structure and the same function and effect as the technical idea within the technical solution scope of the present application are included in the technical scope of the present application. In addition, within the scope of not departing from the gist of the present application, various deformations that can be thought of by those skilled in the art are applied to the embodiments, and other ways constructed by combining some constituent elements of the embodiments are also included in the scope of the present application.

Claims

1. A current collector, characterized in that, It includes an organic film layer, a conductive layer provided on at least one side of the organic film layer, and a conductive particle layer provided between the organic film layer and the conductive layer.

2. The current collector according to claim 1, wherein The material of the organic film layer includes at least one of polyethylene terephthalate, polyvinylidene fluoride, polypropylene, polyethylene, polyvinyl chloride, polycarbonate, polyimide, and polyamideimide.

3. The current collector according to claim 1 or 2, characterized in that, The organic film layer satisfies at least one of the following conditions: (1) The porosity of the organic film layer is 0.1 - 3%; (2) The pore size of the organic film layer is 0.001 - 10 μm; (3) The thickness of the organic film layer is 1 - 20 μm; (4) The tensile strength of the organic film layer is greater than 50 Mpa.

4. The current collector according to any one of claims 1-3, characterized in that, The conductive particles in the conductive particle layer include at least one of conductive nanoparticles, conductive nanowires, and conductive nanotubes; and / or, the material of the conductive particles in the conductive particle layer includes at least one of conductive carbon materials, copper, aluminum, and silver.

5. The current collector according to any one of claims 1-4, characterized in that, The thickness of the conductive particle layer is 0.001 - 5 μm.

6. The current collector according to any one of claims 1-5, characterized in that, The material of the conductive layer includes at least one of copper, aluminum, nickel, titanium, and silver.

7. The current collector according to any one of claims 1-6, characterized in that, The thickness of the conductive layer is 0.1 - 50 μm.

8. A method for preparing a current collector, characterized in that, It includes the following steps: Provide an organic film layer; Set conductive particles on at least one surface of the organic film layer to obtain a conductive particle layer; Set a conductive layer on the conductive particle layer to obtain a current collector.

9. The preparation method according to claim 8, wherein The step of providing an organic film layer includes: Provide an organic film layer; Perform activation treatment on at least one surface of the organic film layer.

10. The preparation method according to claim 9, characterized in that, The activation treatment includes plasma activation or surface oxidation treatment.

11. The preparation method according to any one of claims 8-10, characterized in that, The step of setting conductive particles on at least one surface of the organic film layer to obtain a conductive particle layer includes: Set conductive particles on at least one surface of the organic film layer by spraying or vapor deposition to obtain a conductive particle layer.

12. The preparation method according to claim 11, wherein The slurry used for spraying includes conductive particles, polymers, and solvents. Among them, the mass ratio of the conductive particles in the slurry is 1% - 80%; and / or, the mass ratio of the polymers in the slurry is 10% - 80%.

13. The preparation method according to claim 12, characterized in that, The polymers include at least one of polyacrylic acid, polyvinyl acetate, styrene-butadiene rubber, and polyvinyl alcohol.

14. The preparation method according to any one of claims 8-13, characterized in that, The conductive particles in the conductive particle layer include at least one of conductive nanoparticles, conductive nanowires, and conductive nanotubes; and / or, the material of the conductive particles in the conductive particle layer includes at least one of conductive carbon materials, copper, aluminum, and silver.

15. The preparation method according to any one of claims 8-14, characterized in that, The step of setting a conductive layer on the conductive particle layer to obtain a current collector includes: Deposit a conductive layer on the conductive particle layer by electroplating, vapor deposition, evaporation, or magnetron sputtering to obtain a current collector.

16. A pole piece, characterized in that, It includes the current collector according to any one of claims 1 - 7 or the current collector prepared by the preparation method according to any one of claims 8 - 15.

17. A method for preparing a pole piece, characterized in that It includes the following steps: Provide an organic film layer, and alternately set a to-be-covered area and a blank area on at least one side of the organic film layer; Set conductive metal on the to-be-covered area; Coat at least active materials on the conductive metal, and the active materials include positive electrode active materials or negative electrode active materials; Perform slitting at the blank area to obtain a pole piece.

18. The preparation method according to claim 17, characterized in that, The width of the blank area is 0.1 - 10 mm; optionally, the width of the blank area is 0.1 - 5 mm.

19. The preparation method according to claim 17 or 18, characterized in that, The step of providing an organic film layer and alternately arranging the to-be-covered area and the blank area on at least one side of the organic film layer includes: Providing an organic film layer; Performing activation treatment on at least one side surface of the organic film layer; Alternately arranging the to-be-covered area and the blank area on the surface of the organic film layer after the activation treatment is completed.

20. The preparation method according to claim 19, characterized in that, The activation treatment includes plasma activation or surface oxidation treatment.

21. The preparation method according to any one of claims 17-20, characterized in that, The step of disposing the conductive metal in the to-be-covered area includes: Disposing conductive particles in the to-be-covered area to obtain a conductive particle layer; Providing a conductive layer on the conductive particle layer in the to-be-covered area.

22. The preparation method according to claim 21, wherein, The step of disposing the conductive particles in the to-be-covered area to obtain a conductive particle layer includes: Using a barrier medium to shield the blank area, and disposing the conductive particles on the to-be-covered area by spraying or vapor deposition to obtain a conductive particle layer formed on the to-be-covered area.

23. The preparation method according to claim 22, characterized in that, The slurry used for spraying includes conductive particles, polymers, and solvents, wherein the mass ratio of the conductive particles in the slurry is 1% - 80%; and / or, the mass ratio of the polymers in the slurry is 10% - 80%.

24. The preparation method according to claim 23, characterized in that, The polymers include at least one of polyacrylic acid, polyvinyl acetate, styrene-butadiene rubber, and polyvinyl alcohol.

25. The preparation method according to any one of claims 21-24, characterized in that, The conductive particles in the conductive particle layer include at least one of conductive nanoparticles, conductive nanowires, and conductive nanotubes; and / or, the material of the conductive particles in the conductive particle layer includes at least one of conductive carbon materials, copper, aluminum, and silver.

26. The preparation method according to any one of claims 21-25, characterized in that, The thickness of the conductive particle layer is 0.001 - 5 μm.

27. The preparation method according to any one of claims 21-26, characterized in that, The step of providing a conductive layer on the conductive particle layer in the to-be-covered area includes: Depositing a conductive metal on the conductive particle layer; Removing the barrier medium to obtain a conductive layer.

28. The preparation method according to any one of claims 21-27, characterized in that, The material of the conductive layer includes at least one of copper, aluminum, nickel, titanium, and silver.

29. The preparation method according to any one of claims 21-28, characterized in that, The thickness of the conductive layer is 0.1 - 50 μm.

30. The preparation method according to any one of claims 27-29, characterized in that, The step of depositing a conductive metal on the conductive particle layer includes: Depositing a conductive metal on the conductive particle layer by electroplating, vapor deposition, evaporation, or magnetron sputtering.

31. The preparation method according to claims 22-27, characterized in that, The barrier medium includes insulating tape.

32. A pole piece, characterized in that, The electrode sheet prepared by the preparation method according to any one of claims 18 - 31.

33. According to the electrode sheet of claim 32, the edge of at least one side of the organic film layer extends beyond the edge of the corresponding side of the conductive layer by 0.05 - 5 mm.

34. A battery, characterized in that, Including the electrode sheet of claim 16, or including the electrode sheet prepared by the preparation method according to any one of claims 17 - 31, or including the electrode sheet of claim 32 or 33.

35. An electrical device, characterized in that, Including the battery as claimed in claim 34.

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