Positive electrode current collector, positive electrode sheet, secondary battery, and electronic device

Abstract

The application provides a positive electrode current collector, a positive electrode tab, a secondary battery and an electronic device. The positive electrode current collector comprises iron elements, copper elements and silicon elements. The mass percentage of the iron elements is W Fe , the mass percentage of the copper elements is W Cu , and the mass percentage of the silicon elements is W Si . The thickness of the positive electrode current collector is h μm. The relationship among W Fe , W Cu , W Si and h is within the scope of the application, which can make the positive electrode tab have a higher compaction density and a higher yield, and the secondary battery has a higher energy density.

Description

Technical Field

[0001] This application relates to the field of electrochemical technology, and in particular to a positive current collector, a positive electrode sheet, a secondary battery, and an electronic device. Background Technology

[0002] As the energy density requirements of lithium-ion batteries increase, the core role of aluminum foil as a positive electrode current collector is becoming increasingly prominent. Currently, the industry faces the challenge of achieving a high compaction density (≥4.0 g / cm³). 3 The prominent contradiction between high yield (breakage rate ≤ 0.2 times / km) and high energy density requires higher cold rolling pressure. However, the grain boundary brittleness of aluminum foil is aggravated under high pressure, resulting in a surge in the breakage rate of thin aluminum foil from 8μm to 12μm. If the cold rolling pressure is reduced to ensure yield, the compaction density of the cathode material layer is insufficient, which seriously restricts the capacity of lithium-ion batteries.

[0003] While traditional processes set fixed limits for impurities such as Fe and Cu in aluminum foil (e.g., Fe ≤ 0.1%, Cu ≤ 0.05%), these controls are implemented in isolation, neglecting the interactions between multiple elements and failing to consider the influence of aluminum foil thickness. Therefore, providing a positive electrode current collector that simultaneously achieves high compaction density and high yield is of great significance. Summary of the Invention

[0004] The purpose of this application is to provide a positive electrode current collector, a positive electrode sheet, a secondary battery, and an electronic device, enabling the positive electrode sheet to have high compaction density and high yield, and the secondary battery to have high energy density. The specific technical solution is as follows:

[0005] The first aspect of this application provides a positive electrode current collector comprising iron, copper, and silicon, wherein the mass percentage of iron, based on the mass of the positive electrode current collector, is W. Fe The mass percentage of copper is W. Cu The mass percentage of silicon is W. Si The thickness of the positive electrode current collector is h μm, W Fe W Cu W Si And h satisfy:

[0006]

[0007] Among them, 0.05% ≤ W Fe ≤0.15%, 0.03%≤W Cu ≤0.06%, 0%≤W Si≤0.15%. By adjusting the impurity content within the range of this application and establishing a dynamic mathematical model of Fe-Cu-Si content and the thickness of the positive electrode current collector, positive electrode current collectors of different thicknesses can have both high elongation and high strength, enabling the positive electrode sheet to have high compaction density and high yield, and the secondary battery to have high energy density.

[0008] In one or more embodiments of this application, 0≤W Si / W Fe ≤1.8. By adjusting W Si / W Fe Within the above range, the mass percentage of silicon matches the mass percentage of iron. Silicon can change the morphology of intermetallic compounds, promoting the transformation of coarse and brittle phases into fine and dispersed particles, reducing stress concentration effects. This effect effectively counteracts the embrittlement tendency caused by iron, effectively improving the forming performance of the positive electrode current collector while maintaining the necessary strength. This enables the positive electrode sheet to have higher compaction density and higher yield, and the secondary battery to have higher energy density.

[0009] In one or more embodiments of this application, 0≤W Si / W Cu ≤4. By adjusting W Si / W Cu Within the above range, the mass percentage of silicon is matched with that of copper. Silicon can change the morphology of intermetallic compounds, causing coarse and brittle phases to transform into fine and dispersed particles, reducing stress concentration effects. This effect effectively counteracts the embrittlement tendency caused by copper, and while maintaining the necessary strength, it effectively improves the forming performance of the positive electrode current collector, enabling the positive electrode sheet to have higher compaction density and higher yield, and the secondary battery to have higher energy density.

[0010] In one or more embodiments of this application, 0≤W Si / (W Fe +W Cu )≤1.2. By adjusting W Si / (W Fe +W Cu Within the above range, the mass percentage of silicon matches the sum of the mass percentages of iron and copper. Silicon can change the morphology of intermetallic compounds, promoting the transformation of coarse and brittle phases into fine and dispersed particles, reducing stress concentration effects. This effect further counteracts the embrittlement tendency caused by iron and copper, further improving the forming performance of the positive electrode current collector while maintaining the necessary strength, further increasing the compaction density and yield of the positive electrode sheet, and further increasing the energy density of the secondary battery.

[0011] In one or more embodiments of this application, the positive electrode current collector further includes a first element, wherein the mass percentage of the first element is W based on the mass of the positive electrode current collector. q W Fe W Cu W Si W q And h satisfy: 8≤h≤12, 0.10%≤W Fe +W Cu +W Si +W q ≤0.30%; 12<h≤25, 0.10%≤W Fe +W Cu +W Si +W q ≤0.40%. When the positive electrode current collector also includes the first element, and W Fe W Cu W Si W q Given that h satisfies the above relationship, a dynamic mathematical model is established for the total content of the above impurity elements and the thickness of the positive electrode current collector. The aluminum in the positive electrode current collector has high purity, and the impurity elements have a suitable mass percentage content, so that the positive electrode current collectors of different thicknesses have both high elongation and high strength, which enables the positive electrode sheet to have high compaction density and high yield, and the secondary battery to have high energy density.

[0012] In one or more embodiments of this application, the first element includes at least one selected from magnesium, vanadium, titanium, manganese, or zinc. Selecting the aforementioned first element can further improve the strength of the positive electrode current collector, thereby enabling the positive electrode sheet to achieve a higher yield.

[0013] In one or more embodiments of this application, the tensile strength of the positive electrode current collector is σ MPa, where σ and h satisfy: 8 ≤ h ≤ 12, 180 ≤ σ ≤ 240; 12 < h ≤ 25, 200 ≤ σ ≤ 260. When σ and h satisfy the above relationships, a thinner positive electrode current collector has suitable tensile strength, while a thicker positive electrode current collector has higher tensile strength. This allows positive electrode current collectors of different thicknesses to have both high elongation and high strength, enabling the positive electrode sheet to have high compaction density and high yield, and the secondary battery to have high energy density.

[0014] In one or more embodiments of this application, the elongation of the positive electrode current collector is ε%, and ε and h satisfy: 8≤h≤12, 3.5≤ε≤4.75; 12<h≤25, 4.0≤ε≤7.0. When ε and h satisfy the above relationship, a thinner positive electrode current collector has a suitable elongation, and a thicker positive electrode current collector has a higher elongation. This allows positive electrode current collectors of different thicknesses to have both high elongation and high strength, enabling the positive electrode sheet to have high compaction density and high yield, and the secondary battery to have high energy density.

[0015] A second aspect of this application provides a positive electrode sheet comprising the positive current collector of any of the foregoing embodiments. Therefore, the positive electrode sheet provided by this application has a higher compaction density and a higher yield.

[0016] A third aspect of this application provides a secondary battery that includes the positive electrode sheet found in any of the foregoing embodiments. Therefore, the secondary battery provided by this application has a high energy density.

[0017] A fourth aspect of this application provides an electronic device that includes a secondary battery as described in any of the foregoing embodiments. Therefore, the electronic device provided by this application has superior performance.

[0018] The beneficial effects of this application are:

[0019] This application provides a positive current collector, a positive electrode sheet, a secondary battery, and an electronic device. The positive current collector includes iron, copper, and silicon elements, and the mass percentage of iron element is W based on the mass of the positive current collector. Fe The mass percentage of copper is W. Cu The mass percentage of silicon is W. Si The thickness of the positive electrode current collector is h μm, W Fe W Cu W Si And h satisfy:

[0020]

[0021] Among them, 0.05% ≤ W Fe ≤0.15%, 0.03%≤W Cu ≤0.06%, 0%≤W Si ≤0.15%. A positive electrode current collector meeting these characteristics enables the positive electrode sheet to have a high compaction density and a high yield, resulting in a high energy density for the secondary battery.

[0022] Of course, implementing any product or method of this application does not necessarily require achieving all of the advantages described above at the same time. Detailed Implementation

[0023] The technical solutions of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on this application are within the scope of protection of this application.

[0024] It should be noted that, in the specific embodiments of this application, lithium-ion batteries are used as an example of secondary batteries to explain this application, but the secondary batteries in this application are not limited to lithium-ion batteries.

[0025] Driven by the continuous upgrading of lithium-ion battery energy density, cathode current collectors are rapidly developing towards ultra-thinness and high compaction density. However, traditional processes use fixed limit standards for impurity elements (such as Fe, Cu, etc.), failing to consider the differences in mechanical state of cathode current collectors with different thicknesses. For example, when the aluminum foil of the cathode current collector is thin (≤12μm), using the impurity standard for thick foil leads to insufficient grain boundary strengthening and frequent microcracks during high-pressure rolling; when the aluminum foil is thick (>12μm), it is not conducive to improving compaction density. Based on this, this application provides a cathode current collector, cathode electrode sheet, secondary battery, and electronic device. By constructing a dynamic coupling model of impurity content-thickness of the cathode current collector, the impurity content (e.g., Fe, Cu, Si) of the cathode current collector is correlated with the thickness of the cathode current collector, thereby achieving a synergistic breakthrough in high compaction density and high yield, resulting in a secondary battery with high energy density.

[0026] The first aspect of this application provides a positive electrode current collector comprising iron, copper, and silicon, wherein the mass percentage of iron, based on the mass of the positive electrode current collector, is W. Fe The mass percentage of copper is W. Cu The mass percentage of silicon is W. Si The thickness of the positive electrode current collector is h μm, W Fe W Cu W Si And h satisfy:

[0027]

[0028] Among them, 0.05% ≤ W Fe ≤0.15%, for example, W Fe The value can be 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.10%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, or a range consisting of any two of the above values; 0.03% ≤ W Cu ≤0.06%, for example, W CuThe value can be 0.03%, 0.033%, 0.035%, 0.037%, 0.039%, 0.04%, 0.043%, 0.045%, 0.047%, 0.049%, 0.05%, 0.053%, 0.055%, 0.057%, 0.059%, 0.06%, or a range of any two of the above values; 0% ≤ W Si ≤0.15%, for example, W Si The value can be 0%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.10%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, or a range of any two of the above values. This application does not impose any particular limitation on the positive electrode current collector, as long as it achieves the purpose of this application. For example, the positive electrode current collector may contain aluminum foil. In this application, aluminum foil refers to aluminum alloy foil. The mass percentage W of aluminum element in the positive electrode current collector is specified in this application. Al There are no particular restrictions, as long as the purpose of this application can be achieved. For example, based on the mass of the positive current collector, the mass percentage of aluminum is W. Al 96.0% ≤ W Al ≤99.9%.

[0029] The inventors discovered that for positive electrode current collector aluminum foil, high-purity aluminum (W) Fe +W Cu +W Si(≤0.4%) By reducing the pinning effect of impurity atoms, the free path of dislocation movement is increased by 70%, promoting uniform plastic deformation; the optimized grain boundary structure (low-angle grain boundary ratio >70%) and the activation of the deformation twinning mechanism synergistically provide additional slip paths, thus resulting in good ductility of the positive electrode current collector aluminum foil. When the positive electrode current collector includes iron, copper, and silicon, iron and copper can improve the strength of the positive electrode current collector. For silicon, firstly, silicon can promote grain refinement, enabling the aluminum matrix to form a finer grain structure, which enhances the ductility of the material and reduces crack initiation; secondly, silicon can change the morphology of intermetallic compounds, causing coarse and brittle phases to transform into fine and dispersed particles, reducing stress concentration effects. This dual effect effectively counteracts the embrittlement tendency caused by elements such as iron and copper, effectively improving the forming performance of the positive electrode current collector while maintaining the necessary strength. By establishing a dynamic mathematical model of Fe-Cu-Si content and the thickness of the cathode current collector, precise control of composition and adaptive adjustment of the process can be achieved. This effectively solves the industry problems of high breakage rate in thin foil (≤12μm) and insufficient compaction density in thick foil (>12μm), while also reducing the cost of high-purity aluminum raw materials. Therefore, by controlling the impurity content within the range of this application and establishing a dynamic mathematical model of Fe-Cu-Si content and the thickness of the cathode current collector, the dislocation density can be dynamically controlled to 8×10⁻⁶ during rolling. 13 m -2 Up to 1×10 14 m -2 This allows positive electrode current collectors of different thicknesses to have both high elongation and high strength, enabling the positive electrode sheet to have high compaction density and high yield, and the secondary battery to have high energy density.

[0030] In one or more embodiments of this application, 0≤W Si / W Fe ≤1.8. For example, W Si / W Fe The value can be 0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, or a range of any two of the above values. By adjusting W... Si / W Fe Within the above range, the mass percentage of silicon matches the mass percentage of iron. Silicon can change the morphology of intermetallic compounds, promoting the transformation of coarse and brittle phases into fine and dispersed particles, reducing stress concentration effects. This effect effectively counteracts the embrittlement tendency caused by iron, effectively improving the forming performance of the positive electrode current collector while maintaining the necessary strength. This enables the positive electrode sheet to have higher compaction density and higher yield, and the secondary battery to have higher energy density.

[0031] In one or more embodiments of this application, 0≤W Si / W Cu ≤4. For example, W Si / W Cu The value can be 0, 0.3, 0.5, 0.7, 1.0, 1.3, 1.5, 1.7, 2.0, 2.3, 2.5, 2.7, 3.0, 3.3, 3.5, 3.7, 4, or a range of any two of the above values. By adjusting W... Si / W Cu Within the above range, the mass percentage of silicon is matched with that of copper. Silicon can change the morphology of intermetallic compounds, causing coarse and brittle phases to transform into fine and dispersed particles, reducing stress concentration effects. This effect effectively counteracts the embrittlement tendency caused by copper, and while maintaining the necessary strength, it effectively improves the forming performance of the positive electrode current collector, enabling the positive electrode sheet to have higher compaction density and higher yield, and the secondary battery to have higher energy density.

[0032] In one or more embodiments of this application, 0≤W Si / (W Fe +W Cu )≤1.2. For example, W Si / (W Fe +W Cu The value of ) can be 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, or a range of any two of the above values. By adjusting W... Si / (W Fe +W Cu Within the above range, the mass percentage of silicon matches the sum of the mass percentages of iron and copper. Silicon can change the morphology of intermetallic compounds, promoting the transformation of coarse and brittle phases into fine and dispersed particles, reducing stress concentration effects. This effect further counteracts the embrittlement tendency caused by iron and copper, further improving the forming performance of the positive electrode current collector while maintaining the necessary strength, further increasing the compaction density and yield of the positive electrode sheet, and further increasing the energy density of the secondary battery.

[0033] In one or more embodiments of this application, the positive electrode current collector further includes a first element, wherein the mass percentage of the first element is W based on the mass of the positive electrode current collector. q W Fe W Cu W Si W q And h satisfy: 8≤h≤12, 0.10%≤W Fe +W Cu +WSi +W q ≤0.30%; 12<h≤25, 0.10%≤W Fe +W Cu +W Si +W q ≤0.40%. For example, when 8≤h≤12, W Fe +W Cu +W Si +W q The value can be 0.10%, 0.12%, 0.14%, 0.16%, 0.18%, 0.20%, 0.22%, 0.24%, 0.26%, 0.28%, 0.30%, or a range of any two of the above values; when 12 < h ≤ 25, W Fe +W Cu +W Si +W q The value can be 0.10%, 0.12%, 0.14%, 0.16%, 0.18%, 0.20%, 0.22%, 0.24%, 0.26%, 0.28%, 0.30%, 0.32%, 0.34%, 0.36%, 0.38%, 0.40%, or a range of any two of the above values. The requirements for the total impurity element content differ depending on the thickness of the positive electrode current collector. When the aluminum foil of the positive electrode current collector is thinner (≤12μm), the requirement for the total impurity element content is higher; when the aluminum foil of the positive electrode current collector is thicker (>12μm), the requirement for the total impurity element content is relatively lower. When the positive electrode current collector also includes the first element, and W... Fe W Cu W Si W q Given that h satisfies the above relationship, a dynamic mathematical model is established for the total content of the above impurity elements and the thickness of the positive electrode current collector. The aluminum in the positive electrode current collector has high purity, and the impurity elements have a suitable mass percentage content, so that the positive electrode current collectors of different thicknesses have both high elongation and high strength, which enables the positive electrode sheet to have high compaction density and high yield, and the secondary battery to have high energy density.

[0034] This application specifies the mass percentage content W of the first element. q There are no specific restrictions, as long as the purpose of this application can be achieved. For example, 8 ≤ h ≤ 12, 0% ≤ W q ≤0.22%; 12<h≤25, 0%≤W q ≤0.32%.

[0035] In one or more embodiments of this application, the first element includes at least one selected from magnesium, vanadium, titanium, manganese, or zinc. Selecting the aforementioned first element can further improve the strength of the positive electrode current collector, thereby enabling the positive electrode sheet to achieve a higher yield.

[0036] In one or more embodiments of this application, the tensile strength of the positive current collector is σ MPa, where σ and h satisfy: 8 ≤ h ≤ 12, 180 ≤ σ ≤ 240; 12 < h ≤ 25, 200 ≤ σ ≤ 260. For example, when 8 ≤ h ≤ 12, the value of σ can be 180, 183, 185, 187, 190, 193, 195, 197, 200, 203, 205, 207, 210, 213, 215, 217, 220, 225, 230, 235, 240, or a range consisting of any two of the above values; when 12 < h ≤ 25, the value of σ can be 200, 205, 210, 215, 220, 225, 230, 235, 240, 245, 250, 255, 260, or a range consisting of any two of the above values. There is a certain correlation between the thickness of the positive electrode current collector and its tensile strength. When σ and h satisfy the above relationship, the thinner positive electrode current collector has a suitable tensile strength, and the thicker positive electrode current collector has a higher tensile strength. This allows positive electrode current collectors of different thicknesses to have both high elongation and high strength, enabling the positive electrode sheet to have high compaction density and high yield, and the secondary battery to have high energy density.

[0037] In one or more embodiments of this application, the elongation of the positive current collector is ε%, and ε and h satisfy: 8≤h≤12, 3.5≤ε≤4.75; 12<h≤25, 4.0≤ε≤7.0. For example, when 8 ≤ h ≤ 12, the value of ε can be 3.5, 3.55, 3.6, 3.65, 3.7, 3.75, 3.8, 3.85, 3.9, 3.95, 4.0, 4.05, 4.1, 4.15, 4.2, 4.3, 4.4, 4.5, 4.6, 4.75, or any range of two of the above values; when 12 < h ≤ 25, the value of ε can be 4.0, 4.2, 4.4, 4.6, 4.8, 5.0, 5.2, 5.4, 5.6, 5.8, 6.0, 6.2, 6.4, 6.6, 6.8, 7.0, or any range of two of the above values. There is also a certain correspondence between the thickness of the positive electrode current collector and its elongation. When ε and h satisfy the above relationship, the thinner positive electrode current collector has a suitable elongation, and the thicker positive electrode current collector has a higher elongation. This allows positive electrode current collectors of different thicknesses to have both high elongation and high strength, enabling the positive electrode sheet to have high compaction density and high yield, and the secondary battery to have high energy density.

[0038] This application does not impose any particular limitation on the preparation method of the positive electrode current collector, as long as it can achieve the purpose of this application. For example, the preparation method of the positive electrode current collector may include the following steps: mixing aluminum ingot, iron source, copper source, silicon source and first element source in a certain proportion, and then performing smelting, casting, hot rolling, cold rolling and annealing treatment, followed by slitting and corona treatment to obtain the positive electrode current collector.

[0039] This application does not impose any particular restrictions on the iron source, copper source, silicon source, or first element source, as long as the purpose of this application can be achieved. For example, the iron source may include, but is not limited to, at least one of metallic iron (Fe), ferroalloys, or iron compounds. The aforementioned ferroalloys may include Al-Fe master alloys, and the aforementioned iron compounds may include at least one of Fe2O3 or FeCl3. The copper source may include, but is not limited to, at least one of metallic copper (Cu), copper alloys, or copper compounds. The aforementioned copper alloys may include Al-Cu master alloys, and the aforementioned copper compounds may include at least one of CuO or CuCO3. The silicon source may include, but is not limited to, at least one of elemental silicon (Si), silicon alloys, or silicon compounds. The aforementioned silicon alloys may include Al-Si master alloys, and the aforementioned silicon compounds may include at least one of SiO2 or SiC. The first element source may include, but is not limited to, at least one of elemental metals, alloys, or compounds. The aforementioned elemental metals may include at least one of elemental magnesium, elemental manganese, elemental zinc, elemental vanadium, or elemental titanium. The aforementioned alloys may include Al-Mg master alloys, and the aforementioned compounds may include at least one of MgCO3 or Mn3O4. This application does not impose any particular restrictions on the hot rolling temperature, as long as the purpose of this application can be achieved. For example, the hot rolling temperature can be from 160°C to 300°C.

[0040] In some embodiments of this application, the positive current collector can be subjected to corona treatment simultaneously with the slitting of the positive current collector. This application does not impose any particular limitation on the corona power, as long as it achieves the purpose of this application. For example, the corona power can be from 30kW to 90kW. This application also does not impose any particular limitation on the processing speed of the corona treatment, as long as it achieves the purpose of this application. For example, the processing speed can be from 50m / min to 220m / min. The corona treatment generates plasma through high-voltage discharge. High-energy particles bombard the surface of the positive current collector, triggering a dual effect: physical etching removes organic contaminants, increasing the surface roughness of the positive current collector; chemical activation oxidizes aluminum to generate a nano-oxide layer rich in polar groups (e.g., -OH, -COOH). These two processes synergistically enhance the surface energy of the positive current collector. The presence of polar components can increase the surface dyn value of the positive current collector from below 30 dyn / cm to above 34 dyn / cm. A larger surface dyne value of the positive electrode current collector indicates a higher surface energy and significantly enhanced micro-wetting properties. This is beneficial for the formation of a uniform and dense positive electrode material layer, significantly reducing the coating defect rate (such as pinholes and streaks), and improving the interfacial bonding strength between the positive electrode material layer and the positive electrode current collector, thus better meeting the coating requirements of the positive electrode sheet of secondary batteries.

[0041] This application does not impose any particular restrictions on the method of controlling the mass percentage of iron, copper, and silicon in the positive electrode current collector, as long as the purpose of this application can be achieved. For example, the mass percentage of iron, copper, and silicon can be controlled by adjusting the mass of the added iron source, copper source, and silicon source.

[0042] This application does not impose any particular restrictions on the method of controlling the thickness of the positive electrode current collector, as long as the purpose of this application can be achieved. For example, the thickness of the positive electrode current collector can be controlled by adjusting the pressure and number of casting, hot rolling, or cold rolling processes.

[0043] This application addresses the regulation of W. Si / W Fe There are no particular restrictions on the method used to set the value of W, as long as it achieves the purpose of this application. For example, W can be adjusted... Si and W Fe Each value is used to regulate W Si / W Fe The value of W Si W Fe The control methods are as described above.

[0044] This application addresses the regulation of W. Si / W Cu There are no particular restrictions on the method used to set the value of W, as long as it achieves the purpose of this application. For example, W can be adjusted... Si and W Cu Each value is used to regulate WSi / W Cu The value of W Si W Cu The control methods are as described above.

[0045] This application addresses the regulation of W. Si / (W Fe +W Cu There are no particular restrictions on the method for setting the value of W, as long as it achieves the purpose of this application. For example, it can be achieved by adjusting W... Si W Fe and W Cu Each value is used to regulate W Si / (W Fe +W Cu The value of W Si W Fe and W Cu The control methods are as described above.

[0046] This application does not impose any particular restrictions on the method of controlling the mass percentage content of the first element in the positive electrode current collector, as long as the purpose of this application can be achieved. For example, the mass percentage content of the first element can be controlled by adjusting the mass of the added first element source.

[0047] A second aspect of this application provides a positive electrode sheet comprising the positive current collector of any of the foregoing embodiments. Therefore, the positive electrode sheet provided by this application has a higher compaction density and a higher yield.

[0048] The positive electrode includes a positive current collector and a positive electrode material layer disposed on at least one surface of the positive current collector. The phrase "positive electrode material layer disposed on at least one surface of the positive current collector" means that the positive electrode material layer can be disposed on one surface of the positive current collector along its thickness direction, or on two surfaces of the positive current collector along its thickness direction. It should be noted that "surface" here can refer to the entire surface area of ​​the positive current collector, or only a portion thereof; this application does not impose any particular limitation, as long as the purpose of this application is achieved.

[0049] The positive electrode material layer includes a positive electrode active material. This application does not impose any particular limitation on the positive electrode active material, as long as it achieves the purpose of this application. For example, the positive electrode active material may include, but is not limited to, at least one of lithium cobalt oxide (LiCoO2), lithium nickel cobalt manganese oxide (e.g., NCM811, NCM622, NCM523, NCM111), lithium manganese oxide, lithium nickel oxide, or lithium iron phosphate. The positive electrode material layer may also include a conductive agent and a binder. This application does not impose any particular limitation on the types of conductive agents and binders, as long as they achieve the purpose of this application. For example, the conductive agent may include, but is not limited to, at least one of conductive carbon black, carbon nanotubes (CNTs), carbon fibers, flake graphite, graphene, metallic materials, or conductive polymers. The aforementioned conductive carbon black may include, but is not limited to, at least one of Super P, acetylene black, or Ketjen black. The aforementioned carbon nanotubes may include, but are not limited to, single-walled carbon nanotubes and / or multi-walled carbon nanotubes. The aforementioned carbon fibers may include, but are not limited to, vapor-grown carbon fibers (VGCF) and / or carbon nanofibers. The aforementioned metallic materials may include, but are not limited to, metal powders and / or metal fibers. Specifically, the metal may include, but is not limited to, at least one of copper, nickel, aluminum, or silver. The aforementioned conductive polymer may include, but is not limited to, at least one of polyphenylene derivatives, polyaniline, polythiophene, polyacetylene, or polypyrrole. The binder may include, but is not limited to, at least one of polyvinylidene fluoride (PVDF), a copolymer of PVDF and hexafluoropropylene, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyamide, polyethylene ether, polymethyl methacrylate, polytetrafluoroethylene, polyhexafluoropropylene, styrene-butadiene rubber (SBR), polypropylene, polyethylene, polyetherimide, copolymers of propylene derivatives, or carboxymethyl cellulose salts. The aforementioned carboxymethyl cellulose salts may include, but are not limited to, at least one of sodium carboxymethyl cellulose, potassium carboxymethyl cellulose, or lithium carboxymethyl cellulose. This application does not impose any particular limitation on the mass ratio of the positive electrode active material, conductive agent, and binder in the positive electrode material layer. Those skilled in the art can select according to actual needs, as long as the purpose of this application can be achieved. This application does not impose any particular limitation on the thickness of the positive electrode material layer, as long as the purpose of this application can be achieved. For example, the thickness of a single-sided cathode material layer ranges from 40 μm to 200 μm.

[0050] Optionally, the positive electrode may further include a conductive layer located between the positive current collector and the positive electrode material layer. The composition of the conductive layer is not particularly limited and can be any conductive layer commonly used in the art. The conductive layer includes a conductive agent and a binder. This application does not impose any particular limitation on the conductive agent and binder in the conductive layer; for example, it can be at least one of the aforementioned conductive agents and binders.

[0051] A third aspect of this application provides a secondary battery that includes the positive electrode sheet found in any of the foregoing embodiments. Therefore, the secondary battery provided by this application has a high energy density.

[0052] In this application, the secondary battery further includes a negative electrode sheet. The negative electrode sheet includes a negative current collector and a negative electrode material layer disposed on at least one surface of the negative current collector. The aforementioned "negative electrode material layer disposed on at least one surface of the negative current collector" means that the negative electrode material layer can be disposed on one surface of the negative current collector along its own thickness direction, or on two surfaces of the negative current collector along its own thickness direction. It should be noted that the "surface" here can be the entire area of ​​the negative current collector or a part of the negative current collector; this application has no particular limitation, as long as the purpose of this application is achieved. This application has no particular limitation on the negative current collector, as long as the purpose of this application is achieved, for example, it can include copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, foamed nickel, foamed copper, or composite current collectors, etc.

[0053] The negative electrode material layer of this application includes a negative electrode active material. This application does not impose any particular limitation on the negative electrode active material, as long as it can achieve the purpose of this application. For example, the negative electrode active material may include natural graphite, artificial graphite, mesophase microcarbon spheres (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composites, SiO₂, etc. x (0.5 < x < 1.6), Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO2, spinel-structured lithium titanate Li4Ti5O 12 The negative electrode material layer of this application includes at least one of Li-Al alloy or metallic lithium. The negative electrode material layer further includes a binder and a conductive agent. This application does not impose any particular limitation on the binder and conductive agent in the negative electrode material layer, as long as the purpose of this application can be achieved. For example, the binder may include at least one of the aforementioned binders; the conductive agent may include at least one of the aforementioned conductive agents. This application does not impose any particular limitation on the mass ratio of the negative electrode active material, binder, and conductive agent in the negative electrode material layer. Those skilled in the art can select according to actual needs, as long as the purpose of this application can be achieved.

[0054] This application does not impose any particular limitation on the thickness of the negative electrode current collector, as long as it achieves the purpose of this application. For example, the thickness of the negative electrode current collector can be from 4 μm to 12 μm. This application also does not impose any particular limitation on the thickness of the negative electrode material layer, as long as it achieves the purpose of this application. For example, the thickness of the single-sided negative electrode material layer can be from 30 μm to 250 μm.

[0055] In this application, the secondary battery also includes an electrolyte, which comprises lithium salts and non-aqueous solvents. This application does not impose any particular limitation on the lithium salt, as long as it achieves the purpose of this application. For example, the lithium salt may include, but is not limited to, at least one of LiPF6, LiBF4, LiAsF6, LiClO4, LiB(C6H5)4, LiCH3SO3, LiCF3SO3, LiN(SO2CF3)2, LiC(SO2CF3)3, LiAlCl4, Li2SiF6, LiCl, lithium bis(oxalato)borate (LiBOB), LiBr, or lithium difluoroborate. This application does not impose any particular limitation on the content of the lithium salt in the electrolyte, as long as it achieves the purpose of this application.

[0056] This application does not impose any particular limitation on non-aqueous solvents, as long as they can achieve the purpose of this application. For example, non-aqueous solvents may include, but are not limited to, at least one of carbonate compounds, ester-based compounds, ether-based compounds, ketone-based compounds, alcohol-based compounds, or aprotic solvents. Carbonate compounds may include at least one of chain carbonate compounds, cyclic carbonate compounds, or fluorinated carbonate compounds. Chain carbonate compounds may include diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), or methyl ethyl carbonate (EMC). Cyclic carbonate compounds may include at least one of ethylene carbonate (EC), propylene carbonate (PC), butyl carbonate (BC), or vinyl ethylene carbonate (VEC). Fluorocarbonate compounds may include at least one of fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-difluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene carbonate, or trifluoromethylethylene carbonate. Esters may include at least one of methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, γ-butyrolactone, decanolactone, valproic acid lactone, caprolactone, or methyl formate. Ether-based compounds may include at least one of dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane, 2-methyltetrahydrofuran, or tetrahydrofuran. Ketone-based compounds may include cyclohexanone. Alcohol-based compounds may include at least one of ethanol or isopropanol. Aprotic solvents may include at least one of dimethyl sulfoxide, 1,2-dioxolane, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolium ketone, N-methyl-2-pyrrolidone, formamide, dimethylformamide, acetonitrile, nitromethane, trimethyl phosphate, triethyl phosphate, trioctyl phosphate, or phosphate esters. This application does not impose any particular limitation on the content of non-aqueous solvents in the electrolyte, as long as the purpose of this application is achieved.

[0057] In this application, the secondary battery also includes a separator. The separator is used to separate the positive electrode and the negative electrode, prevent internal short circuits in the secondary battery, allow electrolyte ions to pass freely, and does not affect the electrochemical charging and discharging process. This application does not impose any particular limitation on the separator, as long as it can achieve the purpose of this application. For example, the material of the separator may include, but is not limited to, at least one of polyethylene (PE), polyolefins (PO) mainly composed of polypropylene (PP), polyester (e.g., polyethylene terephthalate (PET) film), cellulose, polyimide (PI), polyamide (PA), spandex, or aramid; the type of separator may include at least one of woven membrane, nonwoven membrane, microporous membrane, composite membrane, rolled membrane, or spun membrane.

[0058] In this application, the diaphragm may include a base membrane and a surface treatment layer. The base membrane may be a nonwoven fabric or composite membrane with a porous structure, and the material of the base membrane may include at least one of polyethylene, polypropylene, polyethylene terephthalate, or polyimide. Optionally, a polypropylene porous membrane, a polyethylene porous membrane, a polypropylene nonwoven fabric, a polyethylene nonwoven fabric, or a polypropylene-polyethylene-polypropylene porous composite membrane may be used. Optionally, a surface treatment layer is provided on at least one surface of the base membrane. The surface treatment layer may be a polymer layer or an inorganic layer, or a layer formed by mixing polymers and inorganic materials. For example, the inorganic layer includes inorganic particles and a diaphragm binder. This application does not particularly limit the aforementioned inorganic particles, and may include at least one of alumina, silicon oxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, or barium sulfate. This application does not particularly limit the aforementioned diaphragm binder, and may include at least one of the aforementioned binders. The polymer layer contains a polymer, the polymer material of which includes at least one of polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride, or poly(vinylidene fluoride-hexafluoropropylene).

[0059] The secondary battery also includes a casing for housing the positive electrode, separator, negative electrode, and electrolyte, as well as other components known in the field of secondary batteries. This application does not limit the scope of these other components. This application does not impose any particular limitation on the casing; it can be a casing known in the art, as long as it achieves the purpose of this application. For example, the casing can be a rigid casing or a flexible casing. The material of the rigid casing can be metal; this application does not limit the type of metal and can use known metal rigid casings, as long as they achieve the purpose of this application. The flexible casing can be a metal plastic film, such as aluminum-plastic film, steel-plastic film, etc.

[0060] This application does not impose any particular limitation on the type of secondary battery, which may include any device in which an electrochemical reaction occurs. In this application, the secondary battery may include, but is not limited to: lithium metal secondary batteries, lithium-ion secondary batteries (lithium-ion batteries), lithium polymer secondary batteries, or lithium-ion polymer secondary batteries, etc.

[0061] The fabrication process of the secondary battery described in this application is well known to those skilled in the art, and this application does not impose any particular limitations. For example, the fabrication process of the secondary battery may include, but is not limited to, the following steps: stacking the positive electrode, separator, and negative electrode in sequence, and performing operations such as winding and folding as needed to obtain a wound electrode assembly; placing the electrode assembly into a housing; injecting electrolyte into the housing and sealing it to obtain the secondary battery. Alternatively, stacking the positive electrode, separator, and negative electrode in sequence, and then fixing the four corners of the entire stacked structure with tape to obtain a stacked electrode assembly; placing the electrode assembly into a housing; injecting electrolyte into the housing and sealing it to obtain the secondary battery.

[0062] A fourth aspect of this application provides an electronic device that includes a secondary battery as described in any of the foregoing embodiments. Therefore, the electronic device provided by this application has superior performance.

[0063] This application does not specifically limit the type of electronic device, which can be any electronic device known in the prior art. In some embodiments, the electronic device may include, but is not limited to, laptops, pen input computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, stereo headphones, video recorders, LCD TVs, portable cleaners, portable CD players, mini CDs, transceivers, electronic notebooks, calculators, memory cards, portable recorders, radios, backup power supplies, motors, automobiles, motorcycles, electric bicycles, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries, and lithium-ion capacitors, etc.

[0064] Example

[0065] The embodiments and comparative examples provided below illustrate the implementation of this application in more detail. Various tests and evaluations were conducted according to the methods described below. Furthermore, unless otherwise specified, "parts" and "%" are quality standards.

[0066] Test methods and equipment:

[0067] Positive current collector sampling method:

[0068] The lithium-ion battery was discharged to 3.0V, and the positive electrode was obtained by disassembly. The positive electrode was then soaked and cleaned with N-methylpyrrolidone (NMP) for 8 hours and rinsed three times with anhydrous ethanol to remove residual active material, thus obtaining the positive current collector.

[0069] The following tests on the thickness, elemental mass percentage, tensile strength, and elongation of the positive current collector were all conducted using the positive current collector obtained in the above manner.

[0070] Thickness test of positive electrode current collector:

[0071] The thickness h of the positive electrode current collector is measured using a micrometer. Twelve different positions are taken on the positive electrode current collector, and the thickness of the positive electrode current collector at each position is measured using a micrometer. The value of h is the average value of the thickness of the positive electrode current collector at the twelve different positions.

[0072] Elemental mass percentage content test:

[0073] The surface of the positive electrode current collector was observed using a Philips XL-30 field emission scanning electron microscope energy dispersive spectroscopy analyzer. Then, the elemental types and mass percentages on the surface of the positive electrode current collector were tested under the conditions of 15kV, 10mA, and 500x magnification.

[0074] Tensile strength and elongation tests:

[0075] A 80mm × 15mm aluminum foil sample of the positive electrode current collector was taken along the rolling direction (i.e., the direction of the current collector's travel). It was fixed on a universal testing machine (model 34TM-5) with a clamp, and the gauge length was set to 50mm. Uniaxial tension was applied at a constant rate of 5mm / min, and load-displacement data was collected in real time until the sample fractured. The tensile strength and elongation of the sample were obtained. The tensile strength was the ratio of the maximum tensile load to the cross-sectional area, and the elongation was the ratio of the displacement change to the initial gauge length. Four samples were taken at equal intervals along the direction of the positive electrode current collector, and the tensile strength and elongation of the four samples were tested. The average value was taken as the tensile strength σ and elongation ε of the positive electrode current collector.

[0076] Maximum compaction density test:

[0077] Take a positive electrode sheet and fold it in half along one side of the cold pressing direction. Roll the folded sheet naturally with a 1.6kg roller without external force. Then fold it in half again along the other side of the cold pressing direction, aligning the crease with the previous crease. Observe whether there are any light-transmitting points at the crease. If there are 1 to 3 small light-transmitting points, the compacted density of the positive electrode sheet at this point is the highest compacted density of the positive electrode sheet.

[0078] Breakage rate test:

[0079] The coated positive electrode sheet was cold-pressed at a speed of 30 m / min. The number of times the positive electrode sheet broke during the cold pressing process at the highest compaction density was collected. The breakage rate = number of breakages / cold pressing kilometers, with the unit being times / kilometer. Here, the cold pressing kilometers refers to the number of kilometers of the cold-pressed positive electrode sheet.

[0080] Energy density test:

[0081] The voltage range indicated on the battery's outer packaging should be used as the standard. For example, if the indicated voltage range is 3.0V to 4.45V, the charging cut-off voltage is 4.45V, and the discharging cut-off voltage is 3.0V. The lithium-ion battery used as an example in this application has a charging cut-off voltage of 4.45V and a discharging cut-off voltage of 3.0V. The specific test steps are as follows: Under 25°C conditions, the lithium-ion battery in the example or comparative example is charged at a constant current of 0.2C to the cut-off voltage of 4.45V, then charged at a constant voltage of 4.45V until the current is 0.05C. After resting for 5 minutes, it is discharged at a constant current of 0.2C to the cut-off voltage of 3.0V, and then rested for 5 minutes. The energy of the above discharge process is recorded as the discharge energy E. The volume V (mm²) of the lithium-ion battery is calculated. 3 = Length × Width × Height.

[0082] Energy density (Wh / L) = E / V × 10 6 .

[0083] Example 1-1

[0084] <Preparation of Positive Electrode Current Collector>

[0085] Aluminum ingots, metallic iron, metallic copper, elemental silicon, elemental magnesium, elemental zinc, elemental manganese, and elemental titanium were mixed in a mass ratio of 99.74:0.07:0.04:0.12:0.008:0.006:0.009:0.007. After melting and dehydrogenation at 720℃, the mixture was double-rolled into a 7.0mm slab (roll speed 2.0m / min). Then, it was slab-opened at 450℃ and hot-rolled to a slab thickness of 2.5mm, with a final rolling temperature of 250℃. After that, it was cold-rolled, annealed after the second pass, and then cold-rolled again under 380 tons of pressure for 5 passes to an aluminum foil thickness of 8μm. At the same time as slitting, a corona treatment was performed, with a precision cutting speed of 200m / min and a corona power of 60kW, to obtain the positive electrode current collector.

[0086] <Preparation of the positive electrode>

[0087] The positive electrode active material is lithium nickel cobalt manganese oxide (NCM811, LiNi). 0.8 Co 0.1 Mn 0.1O2), polyvinylidene fluoride (PVDF) binder, and Super P conductive agent were mixed in a weight ratio of 97.6:1.3:1.1. N-methylpyrrolidone (NMP) was added as a solvent, and the mixture was stirred until homogeneous to obtain a positive electrode slurry with a solid content of 70 wt%. The positive electrode slurry was uniformly coated onto one surface of the positive electrode current collector. After drying, a positive electrode sheet with a single-sided coating of 130 μm thick positive electrode material was obtained. The above steps were repeated on the other surface of the positive electrode current collector to obtain a positive electrode sheet with a double-sided coating of positive electrode material. After drying, cold pressing, and slitting, a positive electrode sheet with dimensions of 74 mm × 867 mm was obtained. The compaction density during the cold pressing process was 4.15 g / cm³. 3 .

[0088] <Preparation of Negative Electrode Sheets>

[0089] Artificial graphite (negative electrode active material), sodium carboxymethyl cellulose (CMC-Na) binder, and styrene-butadiene rubber (SBR) binder were mixed in a weight ratio of 95:2:3. Deionized water was added as a solvent, and the mixture was stirred until homogeneous to obtain a negative electrode slurry with a solid content of 50 wt%. The negative electrode slurry was uniformly coated onto one surface of a 4 μm thick copper foil current collector. After drying, a negative electrode sheet with a single-sided coating of 80 μm thick negative electrode material was obtained. The above steps were repeated on the other surface of the copper foil to obtain a negative electrode sheet with a double-sided coating of negative electrode material. After drying, cold pressing, and slitting, a negative electrode sheet with a specification of 78 mm × 875 mm was obtained. The compaction density during the cold pressing process was 1.2 g / cm³. 3 .

[0090] <Preparation of Electrolyte>

[0091] In an argon-atmospheric glove box with a water content of less than 10 ppm, ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) were mixed in a weight ratio of 1:1:1 to obtain a base solvent. Then, lithium hexafluorophosphate (LiPF6) was added and mixed thoroughly to obtain the electrolyte. Based on the mass of the electrolyte, the mass percentage of lithium salt LiPF6 was 12.5%, with the remainder being the base solvent.

[0092] <Preparation of the diaphragm>

[0093] A 9μm thick polypropylene (PP) film is used.

[0094] <Preparation of Lithium-ion Batteries>

[0095] The prepared positive electrode, separator, and negative electrode are wound together, with the separator positioned between the positive and negative electrodes to provide insulation. After welding the tabs, the electrode assembly is placed in an aluminum-plastic film packaging bag, dried, and then injected with electrolyte. Following vacuum sealing, settling, formation, degassing, and edge trimming processes, a lithium-ion battery is obtained, consisting of 19 layers of positive electrode and 21 layers of negative electrode.

[0096] Examples 1-2 to Examples 1-3

[0097] Except for adjusting the mass ratio of aluminum ingot, metallic iron, metallic copper, elemental silicon, elemental magnesium, elemental zinc, elemental manganese, and elemental titanium in the <Preparation of Positive Electrode Current Collector> so that the mass percentage content of aluminum, iron, copper, silicon, magnesium, zinc, manganese, and titanium is as shown in Table 1, the rest is the same as in Example 1-1.

[0098] Examples 1-4

[0099] Except for the preparation of the positive current collector according to the following method, the rest is the same as in Example 1-1.

[0100] <Preparation of Positive Electrode Current Collector>

[0101] Aluminum ingots, metallic iron, metallic copper, elemental silicon, elemental magnesium, elemental zinc, elemental manganese, and elemental titanium were mixed in a mass ratio of 99.74:0.07:0.04:0.12:0.008:0.006:0.009:0.007. After melting and dehydrogenation at 720℃, the mixture was double-rolled into a 7.0mm slab (roll speed 2.0m / min). Then, it was slab-opened at 450℃ and hot-rolled to a slab thickness of 2.5mm, with a final rolling temperature of 250℃. After that, it was cold-rolled, annealed after the second pass, and then cold-rolled again under 360 tons of pressure for 5 passes to an aluminum foil thickness of 9μm. During the finishing process, a corona treatment was performed at a finishing speed of 200m / min and a corona power of 60kW to obtain the positive electrode current collector.

[0102] Examples 1-5

[0103] Except for the preparation of the positive current collector according to the following method, the rest is the same as in Example 1-1.

[0104] <Preparation of Positive Electrode Current Collector>

[0105] Aluminum ingots, metallic iron, metallic copper, elemental silicon, elemental magnesium, elemental zinc, elemental manganese, and elemental titanium were mixed in a mass ratio of 99.70:0.08:0.04:0.11:0.01:0.03:0.02:0.01. After melting and dehydrogenation at 720℃, the mixture was double-rolled into a 7.0mm slab (roll speed 2.0m / min). Then, it was slab-cut at 450℃ and hot-rolled to a slab thickness of 2.5mm, with a final rolling temperature of 250℃. After that, it was cold-rolled, annealed after the second pass, and then cold-rolled again under 340 tons of pressure for 5 passes to an aluminum foil thickness of 10μm. During the finishing process, a corona treatment was performed at a finishing speed of 200m / min and a corona power of 60kW to obtain the positive electrode current collector.

[0106] Examples 1-6 to Examples 1-7

[0107] Except for adjusting the mass ratio of aluminum ingot, metallic iron, metallic copper, elemental silicon, elemental magnesium, elemental zinc, elemental manganese, and elemental titanium in the <Preparation of Positive Electrode Current Collector> so that the mass percentage content of aluminum, iron, copper, silicon, magnesium, zinc, manganese, and titanium is as shown in Table 1, the rest is the same as in Examples 1-5.

[0108] Examples 1-8

[0109] Except for the preparation of the positive current collector according to the following method, the rest is the same as in Example 1-1.

[0110] <Preparation of Positive Electrode Current Collector>

[0111] Aluminum ingots, metallic iron, metallic copper, elemental silicon, elemental magnesium, elemental zinc, elemental manganese, and elemental titanium were mixed in a mass ratio of 99.74:0.07:0.04:0.12:0.008:0.006:0.009:0.007. After melting and dehydrogenation at 720℃, the mixture was double-rolled into a 7.0mm slab (roll speed 2.0m / min). Then, it was slab-opened at 450℃ and hot-rolled to a slab thickness of 2.5mm, with a final rolling temperature of 250℃. After that, it was cold-rolled, annealed after the second pass, and then cold-rolled again under 320 tons of pressure for 5 passes to an aluminum foil thickness of 11μm. During the finishing process, a corona treatment was performed at a finishing speed of 200m / min and a corona power of 60kW to obtain the positive electrode current collector.

[0112] Examples 1-9

[0113] Except for the preparation of the positive current collector according to the following method, the rest is the same as in Example 1-1.

[0114] <Preparation of Positive Electrode Current Collector>

[0115] Aluminum ingots, metallic iron, metallic copper, elemental silicon, elemental magnesium, elemental zinc, elemental manganese, and elemental titanium were mixed in a mass ratio of 99.74:0.07:0.04:0.12:0.008:0.006:0.009:0.007. After melting and dehydrogenation at 720℃, the mixture was double-rolled into a 7.0mm slab (roll speed 2.0m / min). Then, it was slab-cut at 450℃ and hot-rolled to a 2.5mm thickness, with a final rolling temperature of 250℃. After that, it was cold-rolled, annealed after the second pass, and then cold-rolled again under 300 tons of pressure for 5 passes to an aluminum foil thickness of 12μm. During the finishing process, a corona treatment was performed at a finishing speed of 200m / min and a corona power of 60kW to obtain the positive electrode current collector.

[0116] Examples 1-10

[0117] Except for the preparation of the positive current collector according to the following method, the rest is the same as in Example 1-1.

[0118] <Preparation of Positive Electrode Current Collector>

[0119] Aluminum ingots, metallic iron, metallic copper, elemental silicon, elemental magnesium, elemental zinc, elemental manganese, and elemental titanium were mixed in a mass ratio of 99.60:0.12:0.03:0.08:0.03:0.08:0.05:0.01. After melting and dehydrogenation at 720℃, the mixture was double-rolled into a 7.0mm slab (roll speed 2.0m / min). Then, it was slab-opened at 450℃ and hot-rolled to a slab thickness of 2.5mm, with a final rolling temperature of 250℃. After that, it was cold-rolled, annealed after the second pass, and then cold-rolled again under 280 tons of pressure for 5 passes to an aluminum foil thickness of 13μm. During the finishing process, a corona treatment was performed at a finishing speed of 200m / min and a corona power of 60kW to obtain the positive electrode current collector.

[0120] Examples 1-11 to Examples 1-13

[0121] Except for adjusting the mass ratio of aluminum ingot, metallic iron, metallic copper, elemental silicon, elemental magnesium, elemental zinc, elemental manganese, and elemental titanium in the <Preparation of Positive Electrode Current Collector> so that the mass percentage content of aluminum, iron, copper, silicon, magnesium, zinc, manganese, and titanium is as shown in Table 1, the rest is the same as in Examples 1-10.

[0122] Examples 1-14

[0123] Except for the preparation of the positive current collector according to the following method, the rest is the same as in Example 1-1.

[0124] <Preparation of Positive Electrode Current Collector>

[0125] Aluminum ingots, metallic iron, metallic copper, elemental silicon, elemental magnesium, elemental zinc, elemental manganese, and elemental titanium were mixed in a mass ratio of 99.74:0.07:0.04:0.12:0.008:0.006:0.009:0.007. After melting and dehydrogenation at 720℃, the mixture was double-rolled into a 7.0mm slab (roll speed 2.0m / min). Then, it was slab-cut at 450℃ and hot-rolled to a slab thickness of 2.5mm, with a final rolling temperature of 250℃. After that, it was cold-rolled, annealed after the second pass, and then cold-rolled again under 240 tons of pressure for 5 passes to an aluminum foil thickness of 15μm. During the finishing process, a corona treatment was performed at a finishing speed of 200m / min and a corona power of 60kW to obtain the positive electrode current collector.

[0126] Examples 1-15

[0127] Except for the preparation of the positive current collector according to the following method, the rest is the same as in Example 1-1.

[0128] <Preparation of Positive Electrode Current Collector>

[0129] Aluminum ingots, metallic iron, metallic copper, elemental silicon, elemental magnesium, elemental zinc, elemental manganese, and elemental titanium were mixed in a mass ratio of 99.74:0.07:0.04:0.12:0.008:0.006:0.009:0.007. After melting and dehydrogenation at 720℃, the mixture was double-rolled into a 7.0mm slab (roll speed 2.0m / min). Then, it was slab-opened at 450℃ and hot-rolled to a slab thickness of 2.5mm, with a final rolling temperature of 250℃. After that, it was cold-rolled, annealed after the second pass, and then cold-rolled again under 365 tons of pressure for 4 passes to an aluminum foil thickness of 18μm. During the finishing process, a corona treatment was performed at a finishing speed of 200m / min and a corona power of 60kW to obtain the positive electrode current collector.

[0130] Examples 1-16

[0131] Except for the preparation of the positive current collector according to the following method, the rest is the same as in Example 1-1.

[0132] <Preparation of Positive Electrode Current Collector>

[0133] Aluminum ingots, metallic iron, metallic copper, elemental silicon, elemental magnesium, elemental zinc, elemental manganese, and elemental titanium were mixed in a mass ratio of 99.74:0.07:0.04:0.12:0.008:0.006:0.009:0.007. After melting and dehydrogenation at 720℃, the mixture was double-rolled into a 7.0mm slab (roll speed 2.0m / min). Then, it was slab-cut at 450℃ and hot-rolled to a slab thickness of 2.5mm, with a final rolling temperature of 250℃. After that, it was cold-rolled, annealed after the second pass, and then cold-rolled again under 325 tons of pressure for 4 passes to an aluminum foil thickness of 20μm. During the finishing process, a corona treatment was performed at a finishing speed of 200m / min and a corona power of 60kW to obtain the positive electrode current collector.

[0134] Examples 1-17

[0135] Except for the preparation of the positive current collector according to the following method, the rest is the same as in Example 1-1.

[0136] <Preparation of Positive Electrode Current Collector>

[0137] Aluminum ingots, metallic iron, metallic copper, elemental silicon, elemental magnesium, elemental zinc, elemental manganese, and elemental titanium were mixed in a mass ratio of 99.74:0.07:0.04:0.12:0.008:0.006:0.009:0.007. After melting and dehydrogenation at 720℃, the mixture was double-rolled into a 7.0mm slab (roll speed 2.0m / min). Then, it was slab-opened at 450℃ and hot-rolled to a slab thickness of 2.5mm, with a final rolling temperature of 250℃. After that, it was cold-rolled, annealed after the second pass, and then cold-rolled again under 285 tons of pressure for three passes to an aluminum foil thickness of 22μm. During the finishing process, a corona treatment was performed at a finishing speed of 200m / min and a corona power of 60kW to obtain the positive electrode current collector.

[0138] Examples 1-18

[0139] Except for the preparation of the positive current collector according to the following method, the rest is the same as in Example 1-1.

[0140] <Preparation of Positive Electrode Current Collector>

[0141] Aluminum ingots, metallic iron, metallic copper, elemental silicon, elemental magnesium, elemental zinc, elemental manganese, and elemental titanium were mixed in a mass ratio of 99.60:0.08:0.06:0.07:0.03:0.08:0.05:0.03. After melting and dehydrogenation at 720℃, the mixture was double-rolled into a 7.0mm slab (roll speed 2.0m / min). Then, it was slab-opened at 450℃ and hot-rolled to a slab thickness of 2.5mm, with a final rolling temperature of 250℃. After that, it was cold-rolled, annealed after the second pass, and then cold-rolled again under 225 tons of pressure for three passes to an aluminum foil thickness of 25μm. During the finishing process, a corona treatment was performed simultaneously with the finishing cut at a speed of 200m / min and a corona power of 60kW to obtain the positive electrode current collector.

[0142] Examples 1-19 to Examples 1-20

[0143] Except for adjusting the mass ratio of aluminum ingot, metallic iron, metallic copper, elemental silicon, elemental magnesium, elemental zinc, elemental manganese, and elemental titanium in the <Preparation of Positive Electrode Current Collector> so that the mass percentage content of aluminum, iron, copper, silicon, magnesium, zinc, manganese, and titanium is as shown in Table 1, the rest is the same as in Examples 1-18.

[0144] Comparative Example 1

[0145] Except for adjusting the mass ratio of aluminum ingot, metallic iron, metallic copper, elemental silicon, elemental magnesium, elemental zinc, elemental manganese, and elemental titanium in the <Preparation of Positive Electrode Current Collector> so that the mass percentage content of aluminum, iron, copper, silicon, magnesium, zinc, manganese, and titanium is as shown in Table 1, the rest is the same as in Examples 1-5.

[0146] Comparative Example 2

[0147] Except for adjusting the mass ratio of aluminum ingot, metallic iron, metallic copper, elemental silicon, elemental magnesium, elemental zinc, elemental manganese, and elemental titanium in the <Preparation of Positive Electrode Current Collector> so that the mass percentage content of aluminum, iron, copper, silicon, magnesium, zinc, manganese, and titanium is as shown in Table 1, the rest is the same as in Examples 1-9.

[0148] Comparative Example 3

[0149] Except for adjusting the mass ratio of aluminum ingot, metallic iron, metallic copper, elemental silicon, elemental magnesium, elemental zinc, elemental manganese, and elemental titanium in the <Preparation of Positive Electrode Current Collector> so that the mass percentage content of aluminum, iron, copper, silicon, magnesium, zinc, manganese, and titanium is as shown in Table 1, the rest is the same as in Examples 1-14.

[0150] Comparative Example 4

[0151] Except for adjusting the mass ratio of aluminum ingot, metallic iron, metallic copper, elemental silicon, elemental magnesium, elemental zinc, elemental manganese, and elemental titanium in the <Preparation of Positive Electrode Current Collector> so that the mass percentage content of aluminum, iron, copper, silicon, magnesium, zinc, manganese, and titanium is as shown in Table 1, the rest is the same as in Example 1-1.

[0152] Comparative Example 5

[0153] Except for adjusting the mass ratio of aluminum ingot, metallic iron, metallic copper, elemental silicon, elemental magnesium, elemental zinc, elemental manganese, and elemental titanium in the <Preparation of Positive Electrode Current Collector> so that the mass percentage content of aluminum, iron, copper, silicon, magnesium, zinc, manganese, and titanium is as shown in Table 1, the rest is the same as in Examples 1-18.

[0154] The preparation parameters and electrical performance parameters of each embodiment and comparative example are shown in Table 1.

[0155]

[0156]

[0157]

[0158] As can be seen from Examples 1-1 to 1-20 and Comparative Examples 1 to 5, by adjusting the impurity content within the scope of this application and W Fe W Cu W Si The relationship between W and h satisfies the above formula, indicating that the positive electrode sheet has a higher maximum compaction density and a lower breakage rate, resulting in a higher energy density of the prepared lithium-ion battery. This demonstrates that the compaction density and yield of the positive electrode sheet can be improved, leading to a higher energy density in the secondary battery. (Comparative Examples 1 to 5) Fe W Cu W Si If the relationship between the positive electrode and h does not satisfy the above formula, the maximum compaction density of the positive electrode is low and the breakage rate is high, resulting in a low energy density of the prepared lithium-ion battery. This indicates that the compaction density and yield of the positive electrode are low, and the energy density of the secondary battery is low.

[0159] W Si / W Fe The value of W affects the compaction density of the positive electrode, as well as the yield and energy density of the secondary battery. As can be seen from Examples 1-1 to 1-20, adjusting W... Si / W Fe Within the scope of this application, the highest compaction density of the positive electrode sheet is relatively high and the breakage rate is relatively low, resulting in a higher energy density of the prepared lithium-ion battery. This indicates that the compaction density and yield of the positive electrode sheet can be improved, enabling the secondary battery to have a higher energy density.

[0160] W Si / W Cu The value of W affects the compaction density of the positive electrode, as well as the yield and energy density of the secondary battery. As can be seen from Examples 1-1 to 1-20, adjusting W... Si / W Cu Within the scope of this application, the highest compaction density of the positive electrode sheet is relatively high and the breakage rate is relatively low, resulting in a higher energy density of the prepared lithium-ion battery. This indicates that the compaction density and yield of the positive electrode sheet can be improved, enabling the secondary battery to have a higher energy density.

[0161] W Si / (W Fe +W Cu The value of W affects the compaction density of the positive electrode, its yield, and the energy density of the secondary battery. As can be seen from Examples 1-1 to 1-20, adjusting W... Si / (W Fe +W Cu Within the scope of this application, the highest compaction density of the positive electrode sheet is relatively high and the breakage rate is relatively low, resulting in a higher energy density of the prepared lithium-ion battery. This indicates that the compaction density and yield of the positive electrode sheet can be improved, thus enabling the secondary battery to have a higher energy density.

[0162] W Fe W Cu W Si W q The relationship between W and h affects the compaction density, yield, and energy density of the secondary battery. As can be seen from Examples 1-1 to 1-20, W... Fe W Cu W Si W q If h satisfies the above relationship, the highest compaction density of the positive electrode sheet is higher and the breakage rate is lower, resulting in a higher energy density of the prepared lithium-ion battery. This indicates that the compaction density and yield of the positive electrode sheet can be improved, enabling the secondary battery to have a higher energy density.

[0163] The relationship between σ and h affects the compaction density and yield of the positive electrode sheet, as well as the energy density of the secondary battery. As can be seen from Examples 1-1 to 1-20, σ and h satisfy the above relationship, resulting in a higher maximum compaction density and lower breakage rate of the positive electrode sheet, and a higher energy density of the prepared lithium-ion battery. This indicates that the compaction density and yield of the positive electrode sheet can be improved, thus enabling the secondary battery to have a higher energy density.

[0164] The relationship between ε and h affects the compaction density and yield of the positive electrode sheet, as well as the energy density of the secondary battery. As can be seen from Examples 1-1 to 1-20, ε and h satisfy the above relationship, resulting in a higher maximum compaction density and lower breakage rate of the positive electrode sheet, and a higher energy density of the prepared lithium-ion battery. This indicates that the compaction density and yield of the positive electrode sheet can be improved, thus enabling the secondary battery to have a higher energy density.

[0165] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, or article that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, or article.

[0166] The various embodiments in this specification are described in a related manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0167] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A positive electrode current collector, comprising iron, copper, and silicon, wherein the mass percentage of iron is W based on the mass of the positive electrode current collector. Fe The mass percentage of copper is W. Cu The mass percentage of silicon is W. Si The thickness of the positive current collector is h μm, and the W Fe W Cu W Si And h satisfy: 8≤h＜10， 10≤h≤12， 12＜h≤20， 20＜h≤25， in, 0.05%≤W Fe ≤0.15%,0.03%≤W Cu ≤0.06%,0%≤W Si ≤0.15%。 2. The positive current collector according to claim 1, wherein, 0≤W Si / IN Fe ≤1.8。 3. The positive current collector according to claim 1, wherein, 0≤W Si / IN Cu ≤4。 4. The positive current collector according to claim 1, wherein, 0≤W Si / (IN Fe +W Cu )≤1.2。 5. The positive current collector according to claim 1, wherein, The positive electrode current collector also includes a first element, and the mass percentage of the first element is W based on the mass of the positive electrode current collector. q The W Fe W Cu W Si W q And h satisfy: 8≤h≤12,0.10%≤W Fe +W Cu +W Si +W q ≤0.30%; 12<h≤25,0.10%≤W Fe +W Cu +W Si +W q ≤0.40%。 6. The positive current collector according to claim 5, wherein, The first element includes at least one of magnesium, vanadium, titanium, manganese, or zinc.

7. The positive current collector according to claim 1, wherein, The tensile strength of the positive electrode current collector is σMPa, and σ and h satisfy: 8≤h≤12,180≤σ≤240; 12<h≤25,200≤σ≤260。 8. The positive current collector according to claim 1, wherein, The elongation of the positive current collector is ε%, and ε and h satisfy: 8≤h≤12, 3.5≤ε≤4.75; 12<h≤25,4.0≤ε≤7.0。 9. A positive electrode sheet comprising the positive current collector according to any one of claims 1 to 8.

10. A secondary battery comprising the positive electrode sheet as described in claim 9.

11. An electronic device comprising the secondary battery of claim 10.

Images