A dual-sided heteropolar composite current collector electrode structure with an anchoring layer

Abstract

The application discloses a double-sided heteropolar composite current collector electrode structure with an anchoring layer and a preparation method thereof, and belongs to the technical field of electrochemical energy storage devices. The electrode structure comprises a metal-based composite copper-aluminum current collector foil, the current collector foil has a copper layer on one side and an aluminum layer on the other side, both sides are fully coated with a carbon nanometer anchoring layer, a hard carbon negative electrode layer is arranged on the copper layer side, an active carbon positive electrode layer is arranged on the aluminum layer side, and an insulation margin area is reserved around the electrode layer. The preparation method comprises the steps of substrate flattening, anchoring layer spraying, electrode layer localized coating, gradient drying and margin forming. The copper-aluminum composite structure is used to realize the integrated layout of double-sided heteropoles, and perfectly adapt to the internal multi-layer high-voltage series system. The carbon nanometer anchoring layer greatly improves the coating adhesion and reduces the interface impedance, and solves the pain points that the current current collector cannot adapt to the high-voltage series system and has poor interface stability. The preparation method is suitable for large-scale continuous production, and the yield can reach more than 98%.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage device and industrial manufacturing technology, specifically relating to a double-sided heteropolar composite current collector electrode structure with an anchoring layer adapted to high voltage series scenarios of 800V and above, and a matching preparation method that can be mass-produced. Background Technology

[0002] In large-scale energy storage scenarios such as grid-area energy storage, wind / solar power support in remote areas, backup power for big data data centers, and industrial high-voltage emergency energy storage, existing electrochemical energy storage systems have core defects:

[0003] Low-voltage battery solutions such as lithium iron phosphate batteries and sodium-ion batteries require a large number of individual cells to be connected in series and parallel externally to achieve high-voltage output. They are equipped with complex BMS equalization management, step-up transformers and fire protection systems, resulting in extremely high initial investment and operation and maintenance costs. In addition, they have problems such as short cycle life and thermal runaway safety risks.

[0004] Existing double-layer supercapacitors and hybrid energy storage capacitors are all low-voltage single-cell structures, with the highest single-cell voltage not exceeding 3.8V. They cannot be directly adapted to high-voltage scenarios of 800V and above, and generally use a single copper foil or aluminum foil as the current collector, resulting in the following unresolved pain points:

[0005] 1. A single copper foil is only suitable for the negative electrode, and a single aluminum foil is only suitable for the positive electrode. It is impossible to realize a dual-sided heterogeneous integrated structure with a single positive electrode and an opposite negative electrode. It cannot support a high-voltage architecture with multiple internal series connections. High-voltage output can only be achieved through external series and parallel connections, resulting in high system complexity and high cost.

[0006] 2. The electrode active coating and the current collector are only bonded by an adhesive, which has weak bonding force. During long-term charge and discharge cycles, the coating is prone to peeling off and powdering, resulting in rapid capacity decay of the device and making it difficult to exceed 100,000 cycles.

[0007] 3. The high interfacial contact resistance between the coating and the current collector leads to severe heat generation under high current conditions, which not only reduces energy conversion efficiency but also exacerbates electrolyte decomposition and gas production, posing safety risks of thermal runaway and breakdown in high-voltage scenarios.

[0008] 4. Existing polymer-based composite current collectors have problems such as poor high temperature resistance, poor compatibility with high-voltage organic electrolytes, and easy swelling and deformation, making them unable to operate stably for a long time in high-voltage scenarios of 800V and above; moreover, the existing preparation process is prone to warping and deformation of the current collector, poor coating consistency, low mass production yield, and difficulty in achieving large-scale continuous production.

[0009] Currently, there is no existing technology worldwide that combines "metal-based composite copper-aluminum current collector foil + carbon nanotube anchoring layer + dual-sided heteropolar structure" to adapt to internal multi-layer high-voltage series energy storage systems. Therefore, it is urgent to develop corresponding electrode structures and large-scale preparation methods to solve the core pain points of existing technologies.

[0010] Currently, the highest rated voltage of mainstream hybrid energy storage capacitor cells on the market is only 3.0V. To achieve 800V high-voltage output, at least 267 cells need to be externally connected in series, along with 267 BMS balancing channels. The system complexity is extremely high, and the failure rate is more than 200 times that of the internal series connection scheme. Furthermore, the existing current collectors are all single metal foils, which cannot achieve a double-sided heterogeneous structure and cannot support the internal multi-layer series architecture. Summary of the Invention

[0011] To address the aforementioned deficiencies and gaps in existing technologies, the present invention aims to provide a dual-sided heteropolar composite current collector electrode structure with an anchoring layer and its preparation method. On the one hand, through structural innovation, it achieves an integrated dual-sided heteropolar layout, perfectly adapting to the internal multi-layer high-voltage series system, while significantly improving interfacial bonding and reducing contact impedance. On the other hand, it provides a preparation method that can be mass-produced continuously with high yield, no substrate deformation, and no coating damage, solving the problems of high mass production difficulty and low yield in existing technologies.

[0012] To achieve the above objectives, the present invention adopts the following technical solution:

[0013] First aspect: Electrode structure technical solution

[0014] A double-sided heteropolar composite current collector electrode structure with an anchoring layer includes a metal-based composite copper-aluminum current collector foil. One side of the composite copper-aluminum current collector foil is a continuous, integral copper layer, and the opposite side is a continuous, integral aluminum layer. Both the copper and aluminum surfaces of the composite copper-aluminum current collector foil are fully coated with a continuous carbon nanotube anchoring layer. A hard carbon negative electrode layer is localizedly coated on the outer side of the carbon nanotube anchoring layer on the copper side, and an activated carbon positive electrode layer is localizedly coated on the outer side of the carbon nanotube anchoring layer on the aluminum side. Insulating margins are reserved around both the hard carbon negative electrode layer and the activated carbon positive electrode layer.

[0015] Furthermore, the total thickness of the composite copper-aluminum current collector foil is 60-100 μm, and the thickness ratio of the copper layer to the aluminum layer is 1:1-1:2, taking into account the requirements of current collection conductivity, structural strength and lightweight.

[0016] Furthermore, the carbon nano-anchoring layer is a carbon nanotube layer or a graphene oxide layer, and the thickness of the carbon nano-anchoring layer is 50-100 nm. It is continuously coated across the entire area without any breaks or omissions, serving both as a nano-anchoring structure to enhance the adhesion of the coating and as a conductive transition layer to reduce the interfacial contact resistance.

[0017] Furthermore, the thickness of both the hard carbon negative electrode layer and the activated carbon positive electrode layer is 80-120 μm, with a thickness deviation of ≤±5 μm, to ensure the uniformity of the single-unit voltage when multiple layers are connected in series, and to avoid breakdown problems caused by uneven interlayer voltage.

[0018] Furthermore, the width of the insulating edge area is 1.5 to 3 mm, without electrode coating coverage, for subsequent full encapsulation of interlayer insulation, eliminating the risk of creepage and tip discharge in high-voltage scenarios.

[0019] Furthermore, this electrode structure is used for internal series arrangement of 50 to 380 layers to form a high-voltage hybrid electrochemical energy storage device with a rated operating voltage ≥800V. It directly achieves high-voltage output without the need for external low-voltage individual units connected in series or parallel. The rated operating voltage of a single electrode unit is 3.0~3.2V; 50 layers in series can achieve a rated voltage of 150~160V, and 380 layers in series can achieve a rated operating voltage of 1140~1216V, perfectly adapting to high-voltage energy storage scenarios of 800V and above.

[0020] Second aspect: Preparation method and technical solution

[0021] A method for preparing the above-mentioned double-sided heteropolar composite current collector electrode structure with an anchoring layer includes the following steps:

[0022] S1 Substrate Pretreatment: The composite copper-aluminum current collector foil is subjected to constant tension double-roller leveling and stress relief treatment. The unwinding tension is controlled at 5-8N to eliminate the internal stress of substrate rolling and ensure that the flatness error of the substrate is ≤0.05mm / m, so as to avoid deformation and wrinkles in the subsequent coating and stacking process.

[0023] S2 Anchoring Layer Coating: On the surface of the copper and aluminum layers of the leveled composite copper-aluminum current collector foil, carbon nanoparticle dispersion is continuously sprayed in full width and then dried at a low temperature of 35-45℃ with a gentle breeze to form a continuous and uniform carbon nanoparticle anchoring layer with a thickness of 50-100nm, thus avoiding substrate deformation caused by high temperature drying.

[0024] S3 Electrode Layer Localized Coating: On the outer side of the carbon nano-anchor layer on the copper layer side, a comma-shaped scraper coating process with a fixed edge is used to coat the hard carbon negative electrode slurry; on the outer side of the carbon nano-anchor layer on the aluminum layer side, the same process is used to coat the activated carbon positive electrode slurry. The width of the fixed edge matches the width of the insulation margin area to ensure that the coating edge is neat, burr-free, and free of overflow.

[0025] S4 Gradient Drying and Shaping: The coated electrode sheet is sent into a three-section gradient drying channel for low-temperature drying. The three temperature zones are 35-45℃, 55-65℃, and 70-80℃ respectively, so as to achieve slow and uniform evaporation of solvent and avoid warping and deformation of current collector and shrinkage and peeling of coating caused by rapid drying on one side.

[0026] S5 Edge Forming: An insulating edge area of ​​1.5-3mm is reserved around both the hard carbon negative electrode layer and the activated carbon positive electrode layer. After secondary leveling and electrostatic dust removal, the finished electrode is obtained, which can be directly used in subsequent stacking and series connection processes.

[0027] Furthermore, in step S2, the carbon nanotube dispersion is an aqueous carbon nanotube dispersion or an aqueous graphene oxide dispersion with a solid content of 0.3% to 0.8%, free of organic solvents, environmentally friendly, and has good wettability with the current collector surface, thus forming a continuous and uniform nano-coating.

[0028] Furthermore, in step S3, the wet thickness control accuracy of the comma-shaped doctor blade coating is ≤ ±3μm to ensure the consistency of the electrode layer thickness and adapt to the voltage equalization requirements of multilayer series coating.

[0029] Compared with the prior art, the present invention has the following outstanding advantages:

[0030] 1. Structural innovation achieves breakthrough in high-voltage adaptability: This invention adopts a metal-based composite copper-aluminum current collector foil, with a copper layer on one side adapting to the negative electrode and an aluminum layer on the opposite side adapting to the positive electrode. For the first time, it realizes a dual-sided heterogeneous electrode integrated structure with a single positive electrode and an opposite negative electrode. A single current collector foil can realize the series connection of two adjacent electrode units, perfectly adapting to the internal multi-layer series high-voltage architecture. It can directly realize high voltage output of 800V, 1200V, 1500V and above, without the need for a large number of low-voltage units to be connected in series and parallel externally. It eliminates the need for complex BMS equalization management and step-up transformers, reducing the initial system cost by more than 40%.

[0031] 2. Interface Innovation, Solving Long-Standard Industry Pain Points: This invention sets a full-width continuous carbon nanofiber anchoring layer between the current collector foil and the electrode layer. Through the physical anchoring and chemical bonding of nanomaterials, the bonding force between the electrode coating and the current collector is increased by more than 60%, completely solving the industry pain point of coating peeling and powder shedding during long-term charge-discharge cycles. The device cycle life is increased to more than 200,000 cycles. At the same time, the carbon nanofiber anchoring layer, as a conductive transition layer, eliminates the contact barrier between the current collector and the coating, reducing the interface contact resistance by more than 40%, significantly reducing heat generation under high current conditions, and improving the safety and energy conversion efficiency of high-voltage operation.

[0032] 3. Innovative material system, suitable for harsh high-voltage scenarios: This invention adopts a pure metal-based composite structure without polymer substrate. Its high temperature resistance and compatibility with high-voltage organic electrolytes are far superior to existing polymer-based composite current collectors. There is no risk of swelling, deformation, or decomposition. It can operate stably for a long time in high-voltage scenarios of 800V and above and in a wide temperature range of -40℃ to 60℃, making it perfectly suitable for harsh scenarios such as industrial energy storage and grid energy storage.

[0033] 4. Process innovation, suitable for large-scale mass production: The preparation method of this invention adopts constant tension leveling, low temperature atomization spraying, localized coating, gradient drying and other processes, which avoids substrate deformation caused by high temperature throughout the process, and solves the problems of warping, wrinkles and uneven coating in the production of large-size thin electrode sheets. The mass production yield can reach more than 98%, which can realize continuous and large-scale mass production. The unit manufacturing cost is reduced by more than 30% compared with the existing technology, which has extremely strong industrialization and promotion value. Attached Figure Description

[0034] Figure 1 is a cross-sectional schematic diagram of the electrode structure described in this invention.

[0035] Explanation of reference numerals in the attached diagram: 1 - Composite copper-aluminum current collector foil, 2 - Carbon nano-anchoring layer, 3 - Hard carbon negative electrode layer, 4 - Activated carbon positive electrode layer, 5 - Insulating edge area. Detailed Implementation

[0036] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the scope of protection of the present invention.

[0037] Example 1

[0038] This embodiment discloses a dual-sided heteropolar composite current collector electrode structure with an anchoring layer and its preparation method, as detailed below:

[0039] Electrode structure

[0040] It includes a metal-based composite copper-aluminum current collector foil with a total thickness of 80μm. One side of the current collector foil is a continuous copper layer, and the other side is a continuous aluminum layer. The copper layer is 32μm thick, the aluminum layer is 48μm thick, and the thickness ratio is 1:1.5.

[0041] The copper and aluminum layers of the composite copper-aluminum current collector foil are fully coated with an 80nm thick continuous carbon nanotube anchoring layer, with no breaks or missed areas.

[0042] On the outer side of the carbon nano-anchoring layer on the copper layer side, a 100μm thick hard carbon negative electrode layer is localizedly coated; on the outer side of the carbon nano-anchoring layer on the aluminum layer side, a 100μm thick activated carbon positive electrode layer is localizedly coated, with a thickness deviation ≤±3μm.

[0043] Both the hard carbon negative electrode layer and the activated carbon positive electrode layer have a 2mm wide insulating margin around their perimeter, without any electrode coating covering them.

[0044] Preparation method

[0045] Includes the following steps:

[0046] S1 Substrate Pretreatment: The 80μm thick composite copper-aluminum current collector foil is subjected to constant tension double-roller leveling and stress relief treatment. The unwinding tension is controlled at 6N to eliminate the internal stress of substrate rolling and ensure that the flatness error of substrate is ≤0.05mm / m.

[0047] S2 Anchoring Layer Coating: On the surface of the copper and aluminum layers of the leveled composite copper-aluminum current collector foil, a water-based carbon nanotube dispersion with a solid content of 0.5% is continuously and fully atomized and sprayed, and then dried at a low temperature of 40℃ with a gentle breeze to form a continuous and uniform carbon nanotube anchoring layer with a thickness of 80nm.

[0048] S3 Electrode Layer Localized Coating: On the outer side of the carbon nano-anchor layer on the copper layer side, a comma-shaped scraper coating process with a 2mm fixed edge is used to coat the hard carbon negative electrode slurry; on the outer side of the carbon nano-anchor layer on the aluminum layer side, the same process is used to coat the activated carbon positive electrode slurry, with wet thickness control accuracy ≤ ±3μm, and the coating edges are neat, burr-free, and free of overflow.

[0049] S4 Gradient Drying and Shaping: The coated electrode sheet is sent into a three-stage gradient drying channel with three temperature zones of 40℃, 60℃ and 75℃ respectively, to achieve slow and uniform evaporation of solvent, without substrate warping or coating peeling.

[0050] S5 Edge Forming: A 2mm wide insulating edge area is reserved around the control electrode layer. After secondary leveling and electrostatic dust removal, the finished electrode is obtained.

[0051] The electrode structure prepared in this embodiment has a 72% higher bonding force between the coating and the current collector compared to traditional current collectors, and a 48% lower interfacial contact resistance. When used in a 50-layer internal series arrangement, it can form a high-voltage hybrid electrochemical energy storage capacitor with a rated operating voltage of 800V. After 200,000 cycles, the capacity retention rate is ≥95%, with no coating peeling, no high-voltage breakdown, and no leakage problems. The mass production yield reaches 98.5%.

[0052] Example 2

[0053] The electrode structure and its preparation method disclosed in this embodiment differ from those in Example 1 only in that:

[0054] 1. Electrode structure: The total thickness of the composite copper-aluminum current collector foil is 60μm, and the thickness ratio of the copper layer to the aluminum layer is 1:1; the carbon nano-anchoring layer is a 50nm thick graphene oxide layer; the thickness of both the hard carbon negative electrode layer and the activated carbon positive electrode layer is 80μm; the width of the insulating edge area is 1.5mm.

[0055] 2. Preparation method: Step S1: Unwinding tension is 5N; Step S2: Carbon nanoparticle dispersion is an aqueous graphene oxide dispersion with a solid content of 0.3%, and drying temperature is 35℃; Step S4: The three drying temperature zones are 35℃, 55℃, and 70℃ respectively.

[0056] 3. Application scenarios: This electrode structure is used for internal series arrangement of 380 layers to form a high-voltage energy storage device with a rated operating voltage of 1200V.

[0057] The remaining structural and process parameters are completely consistent with those of Example 1.

[0058] Example 3

[0059] The electrode structure and its preparation method disclosed in this embodiment differ from those in Example 1 only in that:

[0060] 1. Electrode structure: The total thickness of the composite copper-aluminum current collector foil is 100μm, and the thickness ratio of the copper layer to the aluminum layer is 1:2; the thickness of the carbon nano-anchor layer is 100nm; the thickness of the hard carbon negative electrode layer and the activated carbon positive electrode layer is 120μm; the width of the insulating edge area is 3mm.

[0061] 2. Preparation method: Step S1: Unwinding tension is 8N; Step S2: Drying temperature is 45℃; Step S4: The three drying temperature zones are 45℃, 65℃, and 80℃ respectively.

[0062] 3. Application scenarios: This electrode structure is used for internal series arrangement of 94 layers to form an ultra-high voltage energy storage device with a rated operating voltage of 1500V.

[0063] The remaining structural and process parameters are completely consistent with those of Example 1.

Claims

1. A double-sided heteropolar composite current collector electrode structure with an anchoring layer adapted to an internal multilayer series high-voltage energy storage device, characterized in that, The present invention includes a metal-based composite copper-aluminum current collector foil, wherein one side of the composite copper-aluminum current collector foil is a continuous integral copper layer and the opposite side is a continuous integral aluminum layer, and a single current collector foil can realize the series connection of two adjacent electrode units; both the copper layer surface and the aluminum layer surface of the composite copper-aluminum current collector foil are fully coated with a continuous carbon nanotube anchoring layer; a hard carbon negative electrode layer is localizedly coated on the outer side of the carbon nanotube anchoring layer on the copper layer side, and an activated carbon positive electrode layer is localizedly coated on the outer side of the carbon nanotube anchoring layer on the aluminum layer side; insulating margins are reserved around both the hard carbon negative electrode layer and the activated carbon positive electrode layer.

2. The double-sided heteropolar composite current collector electrode structure with anchoring layer according to claim 1, characterized in that, The total thickness of the composite copper-aluminum current collector foil is 60~100μm, and the thickness ratio of the copper layer to the aluminum layer is 1:1~1:

2.

3. The double-sided heteropolar composite current collector electrode structure with anchoring layer according to claim 1, characterized in that, The carbon nanotube anchoring layer is a carbon nanotube layer or a graphene oxide layer, and the thickness of the carbon nanotube anchoring layer is 50-100 nm.

4. The double-sided heteropolar composite current collector electrode structure with anchoring layer according to claim 1, characterized in that, The thickness of both the hard carbon negative electrode layer and the activated carbon positive electrode layer is 80-120 μm, with a thickness deviation of ≤ ±5 μm.

5. The double-sided heteropolar composite current collector electrode structure with anchoring layer according to claim 1, characterized in that, The width of the insulating edge area is 1.5 to 3 mm.

6. The double-sided heteropolar composite current collector electrode structure with anchoring layer according to claim 1, characterized in that, The multilayer electrode structure can be arranged in series internally to form a high-voltage hybrid electrochemical energy storage device.

7. A method for preparing a double-sided heteropolar composite current collector electrode structure with an anchoring layer as described in any one of claims 1-6, characterized in that, Includes the following steps: S1 Substrate Pretreatment: The composite copper-aluminum current collector foil undergoes constant tension double-roller leveling and stress relief treatment, with the unwinding tension controlled at 5~8N to eliminate the internal stress of substrate rolling and ensure that the flatness error of the substrate is ≤0.05mm / m; S2 Anchoring Layer Coating: Carbon nanoparticle dispersion is continuously sprayed onto the copper and aluminum surfaces of the leveled composite copper-aluminum current collector foil using a full-width atomized spraying, and then dried at a low temperature of 35~45℃ with a gentle breeze to form a continuous carbon nanoparticle anchoring layer with a thickness of 50~100nm. S3 Electrode Layer Localized Coating: On the outer side of the carbon nano-anchor layer on the copper layer side, a hard carbon negative electrode slurry is coated using a comma-shaped scraper coating process with fixed baffles; on the outer side of the carbon nano-anchor layer on the aluminum layer side, an activated carbon positive electrode slurry is coated using the same process. S4 Gradient Drying and Shaping: The coated electrode sheet is sent into a three-section gradient drying channel for low-temperature drying. The three temperature zones are 35~45℃, 55~65℃, and 70~80℃ respectively, so as to achieve slow evaporation of solvent and avoid warping and deformation of current collector and coating peeling. S5 Edge Forming: A 1.5~3mm wide insulating edge area is reserved around both the hard carbon negative electrode layer and the activated carbon positive electrode layer. After secondary leveling and electrostatic dust removal, a semi-finished electrode is obtained. S6 Online Inspection: Online visual inspection and tensile testing are performed on the coating thickness, adhesion, and edge area dimensions of the semi-finished electrodes to remove defective products and obtain finished electrodes.

8. The preparation method according to claim 7, characterized in that, In step S2, the carbon nanotube dispersion is an aqueous carbon nanotube dispersion or an aqueous graphene oxide dispersion, with a solid content of 0.3% to 0.8%.

9. The preparation method according to claim 7, characterized in that, In step S3, the width of the fixed edge is matched with the width of the insulation edge area to ensure that the coating edge is neat, burr-free, and free of overflow.

10. The double-sided heteropolar composite current collector electrode structure with anchoring layer according to claim 1, characterized in that, The insulating edge area is a flat metal foil surface without any coating, with a surface roughness Ra≤0.2μm, which is suitable for clamping and positioning in the lamination process.

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