Positive current collector and preparation method thereof, positive plate and solid-state battery

Abstract

The invention provides a composite positive current collector and a preparation method thereof, a positive pole piece and a solid-state battery, and relates to the technical field of solid-state batteries. The composite positive electrode current collector comprises a base film and a current collecting layer, wherein the base film is integrally provided with function partitions; each functional zone comprises a concave zone in the middle zone, a slope transition zone on the edge of the concave zone and an edge protruding zone on the outer side of the transition zone, the concave zones are sequentially arranged in the flow collecting direction, and the thickness of the base film is smoothly and gradually changed from the concave zones to the edges; the current collecting layer is arranged in the concave region; the base film comprises a polyimide base film; and the current collecting layer comprises an aluminum metal current collecting layer. According to the technical scheme, local collapse or structural fracture caused by stress concentration in the cathode overhang area can be avoided, so that the internal short-circuit risk is effectively reduced, and the solid-state battery has the advantage that the safety and reliability of the solid-state battery are remarkably improved.

Description

Technical Field

[0001] This application relates to the field of solid-state battery technology, and in particular to a positive electrode current collector and its preparation method, a positive electrode sheet, and a solid-state battery. Background Technology

[0002] In the manufacturing process of solid-state lithium-ion batteries, isostatic pressing is a critical step, requiring the application of high pressure exceeding 500 MPa to improve the density of the electrode-electrolyte interface. However, since the negative electrode is typically designed to be slightly larger than the positive electrode, forming a specific overhang region, this region is highly susceptible to local collapse or structural fracture under high pressure due to stress concentration, leading to direct contact between the negative and positive electrodes and thus posing an internal short-circuit risk. Existing technologies generally employ the method of printing or coating a film frame in the negative electrode overhang region for isolation and protection, but this approach has significant drawbacks: the dimensional accuracy of the film frame is difficult to control, and its width and thickness are prone to deviation, failing to ensure uniform isolation across the entire cell, leaving localized short-circuit hazards; the film frame material lacks sufficient chemical compatibility with solid electrolytes (such as sulfide or oxide systems), which may adversely affect the overall battery performance; furthermore, the inherent positioning tolerances of the stacking equipment (typically ±0.5 mm) make it difficult to precisely align the film frame with the edge of the positive electrode, causing the positive electrode to easily overlap on the film frame during stacking operations, compromising the insulation function and exacerbating the short-circuit risk. The aforementioned problems severely restrict the safety and reliability of solid-state batteries.

[0003] To address the aforementioned issues, existing technologies urgently need improvement. Summary of the Invention

[0004] The purpose of this application is to provide a composite positive current collector and its preparation method, a positive electrode sheet, and a solid-state battery to solve the above-mentioned problems.

[0005] To achieve the above objectives, this application adopts the following technical solution: This application provides a composite positive electrode current collector, including a base film and a current collector layer, wherein the base film is integrally formed with functional partitions; The functional partition includes a concave area in the middle region, a sloping transition area at the edge of the concave area, and a raised edge area on the outer side of the transition area. The concave areas are arranged sequentially along the flow collection direction, and the thickness of the base film gradually changes smoothly from the concave area to the edge. The current collection layer is disposed in the concave region; The base film includes a polyimide-based film; The current collection layer includes an aluminum metal current collection layer.

[0006] Optionally, the thickness of the base film is 4-8 μm, and the volume resistivity is ≥10. 14 Ω·cm.

[0007] Optionally, the recesses are arranged equidistantly along the longitudinal direction, with each recess having a length of 100-400mm and a width of 50-200mm.

[0008] Optionally, the thickness of the base film in the recessed region is 4-8 μm.

[0009] Optionally, the recessed area is provided with a grid texture of 1-3 μm.

[0010] Optionally, the width of the slope transition zone is 0~2mm.

[0011] Optionally, the width of one side of the raised edge area is 2-4 mm, and the total thickness of one side from the upper surface of the raised area to the flat area of ​​the pit is 20-50 μm.

[0012] This application also provides a method for preparing a composite positive electrode current collector, comprising: The base film is cleaned and dried; the cleaned and dried base film is pressed to obtain an integrally formed concave area, a slope transition area, and an edge protrusion area; the sputtering area is determined, and a metal current collector layer is deposited in the sputtering area; Specifically, the surface of the concave region is activated by argon plasma before depositing the metal current collector layer.

[0013] Optionally, the pressing is hot molding, and the process parameters of the hot molding are: temperature 150~200℃, pressure 0.05~0.1MPa, and time 1~3s.

[0014] Optionally, a mask is used to define the sputtering area, the mask matching the contour of the recessed area with an alignment error not exceeding 0.1 mm.

[0015] Optionally, the process parameters for magnetron sputtering include: target purity ≥ 99.99%, working pressure 0.4-0.6 Pa, power 150-250 W, and deposition thickness 2-5 μm.

[0016] Optionally, the argon plasma activation power is 180-220W, and the time is 1-3min.

[0017] This application also provides a positive electrode sheet, including the positive current collector.

[0018] This application also provides a solid-state battery, including the aforementioned positive electrode.

[0019] Compared with the prior art, the beneficial effects of this application include: The technical solution provided in this application utilizes the design of concave regions, sloping transition regions, and edge protrusion regions within the functional partitioning of the base film, combined with the smooth, gradual thickness variation of the base film. Specifically, the continuous height variation between the concave and sloping transition regions is used to uniformly guide pressure distribution during high-pressure isostatic pressing, thereby reducing stress concentration points in the negative electrode overhang region. The edge protrusion region acts as a physical barrier, directly blocking the deformation expansion of the negative electrode material under high pressure, maintaining insulation between the positive and negative electrodes. A polyimide base film is selected to provide high insulation and excellent mechanical strength, ensuring structural integrity and electrical isolation reliability during high-pressure and high-temperature processes. An aluminum metal current collector layer is deposited to ensure efficient current transmission and good interfacial bonding with the base film. This allows for uniform stress distribution in the current collector during isostatic pressing and high-pressure processes, preventing localized collapse or structural breakage in the negative electrode overhang region due to stress concentration, effectively reducing the risk of internal short circuits and significantly improving the safety and reliability of solid-state batteries. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation on the scope of this application.

[0021] Figure 1 A schematic diagram of the perforation of the composite current collector base membrane provided in the embodiment; Figure 2 This is a schematic diagram of the cross-section of the composite positive electrode current collector after the positive electrode slurry has been coated, as shown in the example. Figure 3 This is a schematic cross-sectional view of the positive electrode sheet provided in the embodiment. Detailed Implementation

[0022] As used in this article: "Prepared from" is synonymous with "comprising". The terms "comprising", "including", "having", "containing", or any other variations thereof as used herein are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0023] The conjunction "composed of..." excludes any unspecified elements, steps, or components. If used in a claim, this phrase makes the claim closed, excluding materials other than those described, except for associated conventional impurities. When the phrase "composed of..." appears in a clause of the body of a claim rather than immediately following it, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0024] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1–5” is disclosed, the described range should be interpreted as including ranges “1–4”, “1–3”, “1–2”, “1–2 and 4–5”, “1–3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0025] In these embodiments, unless otherwise specified, the portions and percentages are all by weight.

[0026] "Parts by mass" refers to the basic unit of measurement that expresses the mass ratio of multiple components. One part can represent any unit mass, such as 1g or 2.689g. If we say that component A has "a" parts by mass and component B has "b" parts by mass, it means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it can mean that the mass of component A is aK and the mass of component B is bK (where K is any number representing a multiplier). It is important to understand that, unlike parts by mass, the sum of the mass parts of all components is not limited to 100 parts.

[0027] "And / or" is used to indicate that one or both of the described situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0028] To better explain the technical solution of this application, the technical solution provided in this application will be described in general before the specific implementation.

[0029] In the manufacturing process of solid-state lithium-ion batteries, the isostatic pressing process requires the application of high pressure to improve the interfacial density between the solid-state battery electrodes and the electrolyte. The overhang region, formed by the negative electrode being slightly larger than the positive electrode, experiences localized stress concentration under high pressure isostatic pressing, leading to collapse or cracking. This results in direct contact between the negative and positive electrodes, causing an internal short circuit. This issue affects battery safety and manufacturing yield, thus restricting product reliability. In the stacking process of sulfide solid electrolyte batteries, the negative electrode overhang region undergoes localized deformation under high pressure. Existing frame insulation solutions suffer from insufficient dimensional accuracy, material compatibility issues with the solid electrolyte, and positioning tolerances in the stacking equipment, preventing precise matching between the frame and the edge of the positive electrode. During stacking, the positive electrode overlaps onto the frame, compromising insulation and increasing the risk of short circuits. Furthermore, this scenario weakens process stability and reduces manufacturing consistency. If the above problems are not solved, internal short circuits will cause thermal runaway during battery charging and discharging; the accumulation of manufacturing defects will continuously affect product consistency, hinder the feasibility of large-scale production, and delay the industrialization process of solid-state battery technology.

[0030] Therefore, in a first aspect, this application provides a composite positive electrode current collector, including a base film and a current collector layer, wherein the base film is integrally formed with functional partitions; The functional partition includes a concave area in the middle region, a sloping transition area at the edge of the concave area, and a raised edge area on the outer side of the transition area. The concave areas are arranged sequentially along the flow collection direction, and the thickness of the base film gradually changes smoothly from the concave area to the edge. The current collection layer is disposed in the concave region; The base film includes a polyimide-based film; The current collection layer includes an aluminum metal current collection layer.

[0031] In one optional embodiment, the thickness of the base film is 4-8 μm, and the volume resistivity is ≥10. 14 Ω·cm.

[0032] The solution in this application precisely limits the thickness of the base film to the range of 4-8 μm, enabling the polyimide base film to effectively disperse stress and maintain structural stability during the isostatic pressing process. Simultaneously, by setting the volume resistivity to be no less than 10... 14 The Ω·cm ensures that the base film can reliably block electron conduction even when the interfacial stress increases under high voltage, thus synergistically solving the structural and insulation failure problems caused by base film performance fluctuations in high-voltage processes. It effectively avoids local collapse or rupture of the base film during high-voltage isostatic pressing processes, while significantly improving electrical insulation reliability and reducing the risk of internal short circuits between the positive and negative electrodes.

[0033] Optionally, the thickness of the base film can be 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, or any value between 4 and 8 μm; the volume resistivity of the base film can be 10. 14 Ω·cm, 2× 14 Ω·cm, 3× 14 Ω·cm, 4× 14 Ω·cm, 5× 14 Ω·cm, 6× 14 Ω·cm, 7× 14 Ω·cm, 8× 14 Ω·cm, 9× 14 Ω·cm, or not less than 10 14 Any value of Ω·cm.

[0034] In one optional embodiment, the recesses are arranged equidistantly along the longitudinal direction, with each recess having a length of 100-400 mm and a width of 50-200 mm.

[0035] The longitudinally equidistant arrangement is adopted to ensure uniform distribution of the positive electrode material during coating and reduce local stress concentration. The regular arrangement and size range control of the concave areas ensure uniform distribution of the positive electrode material and avoid stress concentration caused by local deviations.

[0036] Optionally, the length of each recess can be 100 mm, 150 mm, 200 mm, 250 mm, 300 mm, 350 mm, 400 mm, or any value between 100 and 400 mm; the width of each recess can be 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, 110 mm, 120 mm, 130 mm, 140 mm, 150 mm, 160 mm, 170 mm, 180 mm, 190 mm, 200 mm, or any value between 50 and 200 mm.

[0037] In one optional embodiment, the base film thickness of the recessed region is 4-8 μm.

[0038] The thickness of the base film in the recessed area can be controlled within the range of 4-8μm, which is achieved through the base film forming process. The purpose is to match the overall performance requirements and prevent insulation failure or insufficient strength caused by uneven thickness. The thickness of the recessed area matches the overall performance of the base film, ensuring mechanical strength and insulation reliability under high voltage conditions.

[0039] Optionally, the thickness of the base film in the recessed region can be 4μm, 5μm, 6μm, 7μm, 8μm, or any value between 4 and 8μm.

[0040] In one optional embodiment, the recessed area is provided with a 1-3 μm mesh texture.

[0041] The grid texture within the recessed area refers to the surface microstructure, which can be formed into different patterns using laser engraving or chemical etching. The purpose is to improve the adhesion of the cathode material and prevent the material from falling off during isostatic pressing.

[0042] Optionally, the size of the mesh texture can be 1μm, 2μm, 3μm, or any value between 1 and 3μm.

[0043] In one optional implementation, the width of the ramp transition zone is 2 mm.

[0044] By adjusting the width of the slope transition zone, a smooth gradient of the base film thickness is achieved from the concave area to the edge. As a result, during the 500MPa high-pressure isostatic pressing process, the overall stress distribution of the base film is uniform, and the edge protrusion area can stably support the negative electrode overhang area, effectively isolating the positive and negative electrode contacts and eliminating the risk of short circuit.

[0045] Understandably, this application effectively avoids local stress concentration and rupture of the base film during high-pressure isostatic pressing by using the concave area, ensuring stable support of the edge protrusion area for the negative electrode overhang area, thereby eliminating the risk of internal short circuit.

[0046] In one optional embodiment, the width of the edge protrusion area on one side is 2-4 mm, and the total thickness on one side from the upper surface of the protrusion area to the flat area of ​​the pit is 20-50 μm.

[0047] Optionally, the width of one side of the raised edge area can be 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, or any value between 2 and 4 mm; the total thickness of one side from the upper surface of the raised area to the flattened pit area can be 20 μm, 25 μm, 30 μm, 30 μm, 40 μm, 45 μm, 50 μm, or any value between 20 and 50 μm.

[0048] Secondly, this application also provides a method for preparing a composite positive current collector, comprising: The base film is cleaned and dried; the cleaned and dried base film is pressed to obtain an integrally formed concave area, a slope transition area, and an edge protrusion area; the sputtering area is determined, and a metal current collector layer is deposited in the sputtering area; Specifically, the surface of the concave region is activated by argon plasma before depositing the metal current collector layer.

[0049] In one optional embodiment, the pressing is hot molding, and the process parameters of the hot molding are: temperature 150~200℃, pressure 0.05~0.1MPa, and time 1~3s.

[0050] In an alternative implementation, a mask is used to define the sputtering area, the mask being matched to the contour of the recess with an alignment error not exceeding 0.1 mm.

[0051] Optionally, the alignment error between the mask and the concave contour can be 0.01mm, 0.02mm, 0.03mm, 0.04mm, 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.1mm, or any value between 0.1mm and 0.01mm.

[0052] In one optional embodiment, the process parameters of the magnetron sputtering include: target purity ≥99.99%, working pressure 0.4-0.6Pa, power 150-250W, and deposition thickness 2-5μm.

[0053] Optionally, the target purity can be 99.99%, 99.999%, 99.9999%, or any value not less than 99.99%; the working gas pressure of magnetron sputtering can be 0.4 Pa, 0.45 Pa, 0.5 Pa, 0.55 Pa, 0.6 Pa, or any value between 0.4 and 0.6 Pa; the power of magnetron sputtering can be 150 W, 160 W, 170 W, 180 W, 190 W, 200 W, 210 W, 220 W, 230 W, 240 W, 250 W, or any value between 150 and 250 W; the thickness of the magnetron sputtering can be 2 μm, 3 μm, 4 μm, 5 μm, or any value between 2 and 5 μm.

[0054] In one optional embodiment, the argon plasma activation power is 180-220W, and the time is 1-3min.

[0055] Optionally, the power of argon plasma activation can be 180 W, 185 W, 190 W, 195 W, 200 W, 205 W, 210 W, 215 W, 220 W, or any value between 180 and 220 W; the argon plasma activation time can be 1 min, 2 min, 3 min, or any value between 1 and 3 min.

[0056] This application also provides a positive electrode sheet, including the positive current collector.

[0057] This application also provides a solid-state battery, including the aforementioned positive electrode.

[0058] The implementation schemes of this application will be described in detail below with reference to specific embodiments. However, those skilled in the art will understand that the following embodiments are only for illustrating this application and should not be regarded as limiting the scope of this application. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.

[0059] Example 1 This embodiment provides a composite positive electrode current collector: The positive electrode current collector contains a polyimide-based film and an aluminum metal current collector layer. The polyimide-based film has a thickness of 6 μm and a volume resistivity of 10⁻⁶. 15 Ω·cm.

[0060] The current collector base film is made of polyimide material with a thickness of 6μm. Recessed areas are located in the middle region of the base film, arranged equidistantly in parallel along the longitudinal direction. Each recess is 100mm long and 50mm wide. The base film thickness in the recessed areas is 4μm. The edges of the recessed areas form a sloping transition zone with a width of approximately 2mm. The thickness of the PI base film smoothly transitions from the recessed areas to the raised edge areas. The raised edge areas are located outside the transition zone, with a width of 2mm on each side. Tab areas are provided on one or both sides of the raised edge areas of the current collector, and these tab areas are connected to the recessed areas. Figure 1 As shown, the total thickness on one side from the upper surface of the raised area to the adjacent flat area of ​​the pit is 30 μm. Utilizing the insulating properties of the PI base film itself, this raised structure can physically block the direct contact between the positive electrode active material and the negative electrode overhang area, cutting off potential short-circuit paths.

[0061] This embodiment also provides a method for preparing a composite positive electrode current collector, the specific steps of which are as follows: The PI base film surface was ultrasonically cleaned with deionized water, rinsed with ethanol, and then dried at 80°C for 5 minutes. Subsequently, a molding template of the same size as required was used to hot mold the concave area and the two convex areas on the base film in one step. The molding process parameters were: temperature 180°C, pressure 0.05MPa, and time 2s.

[0062] Aluminum current collector layers were fabricated by magnetron sputtering in the concave and tab regions. A mask precisely matched to the concave contour (window-to-concave alignment accuracy ±0.1 mm, gap 0.3 mm) and a positioning mechanism were used to control the sputtering area. The magnetron sputtering process parameters were: 99.99% aluminum target, target-to-substrate distance 80 mm, background vacuum ≤5 × 10⁻⁵ mm. -4Pa, working pressure 0.5 Pa (argon 30 sccm), power 170 W, temperature 70 °C, deposition thickness 3 μm; no effective deposition in non-target areas. Before sputtering, the surface of the concave area was activated by argon plasma (power 200 W, time 3 min) to graft hydroxyl and carboxyl functional groups, so that the interfacial shear strength between the aluminum layer and the PI base film is ≥5 MPa.

[0063] Conventional positive electrode slurry is intermittently applied to the current collector pits, such as... Figure 2 As shown; after drying, rolling, slitting, and die-cutting, the positive electrode sheet is obtained, as follows: Figure 3 As shown.

[0064] Example 2 This embodiment provides a composite positive electrode current collector: The positive electrode current collector contains a polyimide-based film and an aluminum metal current collector layer. The polyimide-based film has a thickness of 8 μm and a volume resistivity of 10⁻⁶. 15 Ω·cm.

[0065] The current collector base film is made of polyimide material with a thickness of 8 μm. Recessed areas are located in the middle region of the base film, arranged equidistantly in parallel along the longitudinal direction. Each recess is 100 mm long and 50 mm wide. The base film thickness in the recessed areas is 4 μm. The edges of the recessed areas form a sloping transition zone with a width of approximately 2 mm. The thickness of the PI base film smoothly transitions from the recessed areas to the raised edge areas. The raised edge areas are located outside the transition zone, with a width of 2 mm on each side. Tab areas are located on one or both sides of the raised edge areas of the current collector, connected to the recessed areas. The total thickness on one side of the raised area to the adjacent flat area is 40 μm. Utilizing the insulating properties of the PI base film itself, this raised structure can physically block direct contact between the positive electrode active material and the negative electrode overhang area, cutting off potential short-circuit paths.

[0066] This embodiment also provides a method for preparing a composite positive electrode current collector, the specific steps of which are as follows: The PI base film surface was ultrasonically cleaned with deionized water, rinsed with ethanol, and then dried at 80℃ for 5 minutes. Subsequently, a molding template of the same size as required was used to hot mold the concave area and the two convex areas on the base film in one step. The molding process parameters were: temperature 180℃, pressure 0.1MPa, and time 2s.

[0067] Aluminum current collector layers were fabricated by magnetron sputtering in the concave and tab regions. A mask precisely matched to the concave contour (window-to-concave alignment accuracy ±0.1mm, gap 0.3mm) and a positioning mechanism were used to control the sputtering area. The magnetron sputtering process parameters were: 99.99% aluminum target, target-to-substrate distance 80mm, background vacuum ≤5×10⁻⁶. -4Pa, working pressure 0.5 Pa (argon 30 sccm), power 170 W, temperature 70 °C, deposition thickness 3 μm; no effective deposition in non-target areas. Before sputtering, the surface of the concave area was activated by argon plasma (power 200 W, time 3 min) to graft hydroxyl and carboxyl functional groups, so that the interfacial shear strength between the aluminum layer and the PI base film is ≥5 MPa.

[0068] Conventional positive electrode slurry is intermittently coated on the current collector pit, and then dried, rolled, slit, and die-cut to obtain the positive electrode sheet.

[0069] Example 3 This embodiment provides a composite positive electrode current collector: The positive electrode current collector contains a polyimide-based film and an aluminum metal current collector layer. The polyimide-based film has a thickness of 8 μm and a volume resistivity of 10⁻⁶. 15 Ω·cm.

[0070] The current collector base film is made of polyimide material with a thickness of 10 μm. Recessed areas are located in the middle region of the base film, arranged equidistantly in parallel along the longitudinal direction. Each recess is 200 mm long and 100 mm wide. The base film thickness in the recessed areas is 6 μm. The edges of the recessed areas form a sloping transition zone with a width of approximately 2 mm. The thickness of the PI base film smoothly transitions from the recessed areas to the raised edge areas. The raised edge areas are located outside the transition zone, with a width of 3 mm on each side. Tab areas are located on one or both sides of the raised edge areas of the current collector, connected to the recessed areas. The total thickness on one side of the raised area to the adjacent flat area is 50 μm. Utilizing the insulating properties of the PI base film itself, this raised structure can physically block direct contact between the positive electrode active material and the negative electrode overhang area, cutting off potential short-circuit paths.

[0071] This embodiment also provides a method for preparing a composite positive electrode current collector, the specific steps of which are as follows: The PI base film surface was ultrasonically cleaned with deionized water, rinsed with ethanol, and then dried at 80°C for 5 minutes. Subsequently, a molding template of the same size as required was used to hot mold the concave area and the two convex areas on the base film in one step. The molding process parameters were: temperature 180°C, pressure 0.1MPa, and time 2s.

[0072] Aluminum current collector layers were fabricated by magnetron sputtering in the concave and tab regions. A mask precisely matched to the concave contour (window-to-concave alignment accuracy ±0.1mm, gap 0.3mm) and a positioning mechanism were used to control the sputtering area. The magnetron sputtering process parameters were: 99.99% aluminum target, target-to-substrate distance 80mm, background vacuum ≤5×10⁻⁶. -4The working pressure was 0.5 Pa (argon 30 sccm), the power was 170 W, the temperature was 70 °C, and the deposition thickness was 4 μm; no effective deposition occurred in the non-target area. Before sputtering, the surface of the concave area was activated by argon plasma (power 200 W, time 3 min) to graft hydroxyl and carboxyl functional groups, so that the interfacial shear strength between the aluminum layer and the PI base film was ≥5 MPa.

[0073] Conventional positive electrode slurry is intermittently coated on the current collector pit, and then dried, rolled, slit, and die-cut to obtain the positive electrode sheet.

[0074] Comparative Example 1 This comparative example provides a conventional aluminum current collector with a thickness specification of 12μm.

[0075] A UV-coated frame is set at the edge of the negative electrode sheet, with a frame width of 1.5mm and a height of 100μm.

[0076] This comparative example also provides a positive electrode sheet, and the current collector uses conventional aluminum current collector positive electrode slurry as in Example 1.

[0077] Comparative Example 2 This application provides a composite positive electrode current collector: The positive electrode current collector contains a polyimide-based film and an aluminum metal current collector layer. The polyimide-based film has a thickness of 6 μm and a volume resistivity of 10⁻⁶. 15 Ω·cm.

[0078] The only difference between this comparative example and Example 1 is that a polyimide-based film with uniform thickness is used, and an aluminum metal current collector layer is stacked on the surface of the polyimide-based film.

[0079] This comparative example provides a positive electrode sheet, with the same materials and preparation method as in Example 1.

[0080] The electrical properties of the electrode sheets provided in the embodiments and comparative examples are shown in Table 1: Table 1. Electrical properties of the electrode sheets provided in the embodiments and comparative examples.

[0081] The batteries mentioned above were made using the same batch of slurry and negative electrode sheet.

[0082] Isostatic cell determination method: After isostatic pressure, if the OCV of the cell rises compared to that before isostatic pressure, it is a normal cell; if it falls, it is an abnormal cell.

[0083] As shown in Table 1, the current collector used in this invention can provide support for the OVERHANG region, avoiding short circuits caused by edge collapse during isostatic pressing.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0085] Furthermore, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, in the foregoing claims, any of the claimed embodiments can be used in any combination. The information disclosed in this background section is intended only to enhance the understanding of the general background of this application and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

Claims

1. A composite positive electrode current collector, characterized in that, It includes a base membrane and a current collector layer, wherein the base membrane is integrally formed and has functional partitions; The functional partition includes a concave area in the middle region, a sloping transition area at the edge of the concave area, and a raised edge area on the outer side of the transition area. The concave areas are arranged sequentially along the flow collection direction, and the thickness of the base film gradually changes smoothly from the concave area to the edge. The current collection layer is disposed in the concave region; The base film includes a polyimide-based film; The current collection layer includes an aluminum metal current collection layer.

2. The composite positive electrode current collector according to claim 1, characterized in that, The thickness of the base film is 4-8 μm, and the volume resistivity is ≥10. 14 Ω·cm.

3. The composite positive electrode current collector according to claim 1, characterized in that, Meet any one of the following conditions: a. The recessed areas are arranged at equal intervals along the longitudinal direction, and the length of each recessed area is 100-400mm and the width is 50-200mm; b. The thickness of the base film in the recessed region is 4-8 μm; c. The recessed area is provided with a 1-3μm mesh texture; d. The width of the slope transition zone is 0~2mm.

4. The composite positive electrode current collector according to any one of claims 1-3, characterized in that, The width of the raised edge area on one side is 2-4mm, and the total thickness of the raised area to the flat area on one side is 20-50μm.

5. A method for preparing the composite positive electrode current collector according to any one of claims 1-4, characterized in that, include: The base film is cleaned and dried; the cleaned and dried base film is pressed to obtain an integrally formed concave area, a slope transition area, and an edge protrusion area. Define the sputtering region and deposit a metal current collector layer in the sputtering region; Specifically, the surface of the concave region is activated by argon plasma before depositing the metal current collector layer.

6. The preparation method according to claim 5, characterized in that, The pressing is a hot molding process, and the process parameters for the hot molding are: temperature 150~200℃, pressure 0.05~0.1MPa, and time 1~3s.

7. The preparation method according to claim 5, characterized in that, The sputtering area is defined by a mask template, which matches the contour of the recessed area with a alignment error of no more than 0.1 mm.

8. The preparation method according to any one of claims 5-7, characterized in that, At least one of the following conditions must be met: A. The process parameters for magnetron sputtering include: target purity ≥ 99.99%, working pressure 0.4-0.6 Pa, power 150-250 W, and deposition thickness 2-5 μm; B. The argon plasma activation power is 180-220W, and the time is 1-3min.

9. A positive electrode plate, characterized in that, Includes the positive current collector as described in any one of claims 1-4.

10. A solid-state battery, characterized in that, Includes the positive electrode sheet as described in claim 9.

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