Biomass porous carbon composite electrode adaptive to high-voltage serial energy storage device and preparation method of biomass porous carbon composite electrode

Abstract

The invention discloses a biomass porous carbon composite electrode adaptive to a high-voltage series energy storage device and a preparation method of the biomass porous carbon composite electrode, and belongs to the technical field of electrochemical energy storage devices. The composite electrode comprises a metal-based composite copper-aluminum foil current collector, a carbon nano anchoring layer with the thickness of 50-100 nm and a biomass porous carbon active layer, a hard carbon negative electrode is coated with a copper layer on one side of the current collector, an activated carbon positive electrode is coated with an aluminum layer on the other side of the current collector, and a double-side heteropolar structure is formed. The preparation method comprises the steps of biomass porous carbon preparation, anchoring layer coating, active layer coating and drying and rolling. The problems of interface bonding force and contact resistance of the current collector and the active layer are solved at the same time through the carbon nano anchoring layer, the biomass porous carbon adapts to a voltage window of a high-voltage electrolyte with the voltage of 3.2 V or above, the cycle life is larger than or equal to 200 thousand times, the cost is reduced by 60% or above compared with a traditional carbon material, and the mass production requirement of 800 V or above internal multi-layer series high-voltage energy storage devices is perfectly met.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage device and material preparation technology, specifically relating to a biomass porous carbon composite electrode adapted to 800V and above internal multilayer series high voltage energy storage devices and its preparation method. Background Technology

[0002] In large-scale energy storage scenarios such as grid substation energy storage and industrial high-voltage backup, high-voltage energy storage devices with multiple internal series connections can directly output high voltages of 800V and above, significantly simplifying the system structure. Electrode materials are the core of high-voltage energy storage devices, directly determining their performance and cost.

[0003] Existing biomass porous carbon patents have the following drawbacks:

[0004] 1. The activation process only protects the material itself, without any adaptation design for high-voltage series scenarios;

[0005] 2. The active layer has poor adhesion to the current collector and is prone to detachment under high pressure and long cycle, resulting in increased internal resistance and capacity decay;

[0006] 3. The electrode design lacks a suitable internal series structure for dual-sided dissimilar electrodes, making it unsuitable for direct application in high-voltage direct output systems.

[0007] Currently, no patents worldwide protect the combination of "biomass porous carbon + carbon nanotube anchoring layer + metal-based composite copper-aluminum foil double-sided heteropolar structure", therefore, there is an urgent need to develop corresponding composite electrodes and their preparation methods. Summary of the Invention

[0008] The purpose of this invention is to provide a biomass porous carbon composite electrode adapted to high-voltage series energy storage devices and its preparation method. The carbon nanotube anchoring layer solves the problems of interfacial bonding force and impedance, and is adapted to the internal series structure of the two-sided dissimilar electrodes, which greatly reduces the manufacturing cost of high-voltage energy storage devices.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] First aspect: Composite electrode technology solution

[0011] A biomass porous carbon composite electrode adapted to high-voltage series energy storage devices includes a metal-based composite copper-aluminum foil current collector, a carbon nanotube anchoring layer, and a biomass porous carbon active layer.

[0012] The metal-based composite copper-aluminum foil current collector has a copper layer on one side and an aluminum layer on the other side; a carbon nano-anchoring layer is fully coated on both sides of the current collector with a thickness of 50~100nm; a biomass porous carbon active layer is coated on the surface of the anchoring layer, with a hard carbon negative electrode on the copper layer side and an activated carbon positive electrode on the aluminum layer side, forming a double-sided heteropolar structure.

[0013] Furthermore, the carbon nanotube anchoring layer is composed of carbon nanotubes or graphene oxide, forming a continuous conductive network and simultaneously enhancing interfacial bonding; the biomass porous carbon is prepared from coconut shells, bamboo charcoal, or straw, with a specific surface area of ​​[missing information]. With a pore size distribution of 2~50nm, it is suitable for high-voltage electrolytes above 3.2V.

[0014] Furthermore, an insulation margin of 1.5~3mm is reserved around the electrodes, perfectly adapting to the SO2 non-destructive lamination and SO3 edge full encapsulation process, for high-voltage energy storage devices with 50~120 layers connected in series, with a rated operating voltage ≥800V.

[0015] Second aspect: Preparation method and technical solution

[0016] A method for preparing a biomass porous carbon composite electrode includes the following steps:

[0017] S1 Biomass Porous Carbon Preparation: After washing, crushing and sieving the biomass raw material, carbonize it at 500℃ for 1 hour under a nitrogen atmosphere, then add KOH at an alkali-to-carbon ratio of 3:1, activate it at 800℃ for 2 hours, acid wash and water wash until neutral, and dry to obtain biomass porous carbon powder.

[0018] S2 Anchoring Layer Coating: Carbon nanotube dispersion (1wt% solid content) is uniformly coated on both sides of a 20μm thick copper-aluminum composite foil, and dried at 100℃ to form an 80nm thick carbon nanotube anchoring layer.

[0019] S3 Active layer coating: Hard carbon negative electrode slurry (hard carbon: conductive agent: binder = 85:10:5) and activated carbon positive electrode slurry (activated carbon: conductive agent: binder = 88:7:5) are prepared respectively and coated on the copper layer side and aluminum layer side of the current collector in sequence.

[0020] S4 Drying and Rolling: Vacuum drying at 120℃ for 12h, rolling to the preset thickness under 10MPa pressure, and cutting to obtain a 300mm×200mm composite electrode with a 2mm insulation margin reserved around the perimeter.

[0021] Compared with the prior art, the present invention has the following outstanding advantages:

[0022] 1. Significant improvement in interface performance: The carbon nanotube anchoring layer increases the bonding force between the active layer and the current collector from 2N / cm to over 8N / cm, reduces the interface impedance by 50%, and increases the cycle life from 50,000 cycles to over 200,000 cycles.

[0023] 2. Significantly reduced costs: Biomass porous carbon prepared from agricultural waste reduces raw material costs by more than 60% compared to traditional petroleum-based carbon materials, giving it a strong competitive edge in industrialization.

[0024] 3. Perfectly compatible with high-voltage series systems: The dual-sided heteropolar structure is fully compatible with the internal multi-layer series system, and can directly achieve high voltage output of 800V and above without the need for external series and parallel connections.

[0025] 4. Mature technology and easy mass production: All processes are existing mature coating processes that can be directly connected to existing electrode production lines without the need for additional large-scale equipment. Attached Figure Description

[0026] Figure 1 This is a schematic cross-sectional view of the biomass porous carbon composite electrode described in this invention.

[0027] Figure 2 This is a schematic diagram of the planar structure of the biomass porous carbon composite electrode described in this invention;

[0028] Figure 3 This is a schematic diagram illustrating the application of the biomass porous carbon composite electrode described in this invention in a high-voltage series energy storage device.

[0029] 1-Metal-based composite copper-aluminum foil current collector, 2-Copper layer, 3-Aluminum layer, 4-Carbon nano-anchoring layer, 5-Hard carbon negative electrode active layer, 6-Activated carbon positive electrode active layer, 7-Insulating edge area, 8-Electrode active area, 9-Multilayer series cell body, 10-Dual-sided heterogeneous composite electrode, 11-Separator, 12-Stepped insulating edge sealing layer, 13-Injection hole. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to specific embodiments.

[0031] Example 1

[0032] The biomass porous carbon composite electrode described in this embodiment uses a 20μm thick copper-aluminum composite foil current collector, with each copper and aluminum layer being 10μm thick; both sides are coated with an 80nm thick carbon nanotube anchoring layer; the copper layer side is coated with a 100μm thick coconut shell-based hard carbon negative electrode, and the aluminum layer side is coated with a 120μm thick coconut shell-based activated carbon positive electrode; the electrode size is 300mm×200mm, with a 2mm wide insulating edge reserved around the perimeter.

[0033] The preparation method is as follows:

[0034] 1. Preparation of porous biomass carbon: Coconut shells are washed, crushed, and sieved to 200 mesh. They are then carbonized at 500℃ for 1 hour under a nitrogen atmosphere. KOH is added at a alkali-to-carbon ratio of 3:1, and the mixture is activated at 800℃ for 2 hours. After acid washing and water washing until neutral, the carbon is dried at 120℃ to obtain porous biomass carbon powder with a specific surface area of ​​[missing information]. ;

[0035] 2. Anchoring layer coating: Carbon nanotube dispersion (1wt% solid content) is coated on both sides of the current collector and dried at 100℃ to form an 80nm thick anchoring layer;

[0036] 3. Active layer coating: Hard carbon negative electrode slurry and activated carbon positive electrode slurry are prepared separately and coated on both sides of the current collector in sequence;

[0037] 4. Drying and rolling: Vacuum drying at 120℃ for 12h, rolling at 10MPa, and cutting to obtain the finished electrode.

[0038] This electrode is used in a 320V high-voltage energy storage device with 100 layers connected in series. After 200,000 cycles, the capacity retention rate is 96.2% and the internal resistance increase rate is ≤5%.

Claims

1. A biomass porous carbon composite electrode adapted to high-voltage series energy storage devices, characterized in that... It includes a metal-based composite copper-aluminum foil current collector, a carbon nanotube anchoring layer, and a biomass porous carbon active layer; The metal-based composite copper-aluminum foil current collector has a copper layer on one side and an aluminum layer on the other side; The carbon nanotube anchoring layer is fully coated on both sides of the current collector, with a thickness of 50~100nm; The biomass porous carbon active layer is coated on the surface of the carbon nano-anchor layer, the copper layer side is the hard carbon negative electrode active layer, and the aluminum layer side is the activated carbon positive electrode active layer, forming a double-sided heterogeneous composite electrode.

2. The composite electrode according to claim 1, characterized in that... The carbon nano-anchoring layer is formed by coating carbon nanotubes or graphene oxide dispersion, forming a continuous conductive network with the current collector and the biomass porous carbon active layer.

3. The composite electrode according to claim 1, characterized in that... The raw material for the biomass porous carbon active layer is coconut shell, bamboo charcoal, or straw-based biomass carbon, with a specific surface area of ​​[missing information]. The pore size distribution is 2~50nm.

4. The composite electrode according to claim 1, characterized in that... The composite electrode has an insulating edge area of ​​1.5~3mm wide around its perimeter. The insulating edge area has no active layer or anchoring layer.

5. The composite electrode according to claim 1, characterized in that... The bonding force between the carbon nanotube anchoring layer and the current collector is ≥5N / cm, and the bonding force between the carbon nanotube anchoring layer and the biomass porous carbon active layer is ≥8N / cm.

6. A method for preparing a biomass porous carbon composite electrode as described in any one of claims 1-5, characterized in that, Includes the following steps: S1 Biomass Porous Carbon Preparation: Biomass porous carbon powder is prepared by pretreatment, carbonization and activation of biomass raw materials; S2 Anchoring Layer Coating: Carbon nanotubes or graphene oxide dispersions are uniformly coated on both sides of the metal-based composite copper-aluminum foil current collector, and after drying, a carbon nanotube anchoring layer is formed. S3 Active layer coating: Hard carbon negative electrode slurry and activated carbon positive electrode slurry are prepared separately and coated sequentially on the anchoring layer surface of the copper layer side and aluminum layer side of the current collector. S4 Drying and Rolling: The coated electrode is dried and rolled to a preset thickness, and then cut to obtain a composite electrode of a preset size.

7. The preparation method according to claim 6, characterized in that, In step S1, the activation process uses KOH activation method, with an activation temperature of 700~900℃ and an activation time of 1~3h.

8. The preparation method according to claim 6, characterized in that, In step S2, the solid content of the carbon nanotube or graphene oxide dispersion is 0.5~2wt%, the coating thickness is 50~100nm, and the drying temperature is 80~120℃.

9. The preparation method according to claim 6, characterized in that, In step S3, the solid content of the hard carbon negative electrode slurry and the activated carbon positive electrode slurry is 40~60wt%, and the coating speed is 5~20m / min.

10. The preparation method according to claim 6, characterized in that, In step S4, the rolling pressure is 5~15MPa, and the compaction density of the active layer after rolling is... .

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