A doped porous carbon electrode and its application in high-voltage series hybrid energy storage devices

Abstract

The application discloses a kind of doped porous carbon electrode and its application in high-voltage series hybrid energy storage device, belong to electrochemical energy storage device technical field.The electrode includes metal-based composite copper aluminum foil current collector, 50~100nm thick carbon nano anchoring layer and doped porous carbon active layer, copper layer side is nitrogen-doped hard carbon negative electrode, aluminum layer side is boron-doped activated carbon positive electrode, forms double-sided heteropolar structure.Nitrogen / boron doping introduces weak pseudo-capacitance, improves energy density without loss of cycle life, while inhibiting gas production under high pressure.The application perfectly adapts internal multilayer series high-voltage energy storage device, the whole package energy density can reach 50~55Wh / kg, more than 30% higher than traditional biomass carbon electrode, cycle life ≥150,000 times, gas production rate is reduced by more than 50%, greatly improves the comprehensive performance of high-voltage energy storage device.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage device and material preparation technology, specifically relating to a nitrogen / boron doped porous carbon electrode and its application in an internal multilayer series high-voltage hybrid energy storage device of 800V and above. Background Technology

[0002] Hybrid energy storage devices combine the high power and long cycle life of supercapacitors with the high energy density of batteries, making them an ideal choice for grid-area energy storage and industrial high-voltage backup applications. Existing nitrogen / boron-doped porous carbon patents suffer from the following fatal flaws:

[0003] 1. Protecting only the material itself: All existing patents protect only the preparation process of the doped carbon material, without any system adaptation design for high voltage series scenarios;

[0004] 2. Only suitable for low-pressure systems: Existing doped carbon electrodes are used in supercapacitors in aqueous or organic systems below 2.7V, and cannot be adapted to high-voltage electrolytes above 3.5V, resulting in severe gas generation under high voltage;

[0005] 3. No dual-sided polarity structure design: It cannot be directly applied to internal multi-layer series high voltage direct output systems, requiring additional series and parallel connections, resulting in high system costs;

[0006] 4. Poor interfacial bonding: The bonding between the doped carbon active layer and the current collector is weak, and it is easy to fall off under high voltage and long cycle, resulting in increased internal resistance and capacity decay.

[0007] Currently, no patents worldwide protect the combination of "nitrogen / boron doped porous carbon + carbon nanotube anchoring layer + metal-based composite copper-aluminum foil double-sided heteropolar structure + internal multilayer high-voltage series application". Therefore, there is an urgent need to develop corresponding doped porous carbon electrodes and their application solutions. Summary of the Invention

[0008] To address the aforementioned deficiencies in existing technologies, the present invention aims to provide a doped porous carbon electrode and its application in a high-voltage series hybrid energy storage device. This electrode introduces weak pseudocapacitance through nitrogen / boron doping to enhance energy density while suppressing gas generation under high voltage. It also solves the interfacial bonding problem through a carbon nanotube anchoring layer and is perfectly compatible with internal multilayer series high-voltage direct-output systems.

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

[0010] First aspect: Doped porous carbon electrode technology solution

[0011] A doped porous carbon electrode includes a metal-based composite copper-aluminum foil current collector, a carbon nanotube anchoring layer, and a doped 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 doped porous carbon active layer is coated on the surface of the anchoring layer, with a nitrogen-doped hard carbon negative electrode on the copper layer side and a boron-doped activated carbon positive electrode on the aluminum layer side, forming a double-sided heteropolar structure.

[0013] Furthermore, nitrogen doping is 2-5 at%, boron doping is 1-3 at%, and an appropriate amount of weak pseudocapacitance is introduced to improve capacitance without sacrificing cycle life; specific surface area With a pore size distribution of 2~50nm, it is compatible with high-voltage organic electrolytes above 3.5V and suppresses gas generation under high pressure.

[0014] Furthermore, the carbon nanotube anchoring layer increases the bonding force between the active layer and the current collector to ≥8N / cm and reduces the interface impedance by more than 50%; a 1.5~3mm insulating edge area is reserved around the electrode, which is perfectly compatible with SO2 non-destructive stacking and SO3 edge full encapsulation processes.

[0015] Second aspect: Preparation method and technical solution

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

[0017] S1 doped porous carbon preparation: Coconut shell biomass carbon precursor is mixed with urea (nitrogen source) or boric acid (boron source) at a mass ratio of 4:1, carbonized at 600℃ for 1h under nitrogen atmosphere, then KOH is added at an alkali-to-carbon ratio of 3:1, activated at 850℃ for 2h, acid washed and water washed until neutral, and dried to obtain nitrogen-doped hard carbon powder and boron-doped activated carbon powder, respectively.

[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: Nitrogen-doped hard carbon negative electrode slurry (doped hard carbon: conductive agent: binder = 85:10:5) and boron-doped activated carbon positive electrode slurry (doped activated carbon: conductive agent: binder = 88:7:5) were prepared and coated sequentially on the copper layer side and aluminum layer side of the current collector.

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

[0021] Third aspect: High-voltage series application technology solutions

[0022] An application of a doped porous carbon electrode in a high-voltage series hybrid energy storage device involves alternately stacking the prepared doped porous carbon electrode with a separator to form an internal series cell of 50 to 380 layers. After being fully encapsulated and insulated with SO3 edges, a 16V high-voltage organic electrolyte is injected to obtain a high-voltage hybrid energy storage device with a rated operating voltage of 160 to 1216V.

[0023] Compared with the prior art, the present invention has the following outstanding advantages:

[0024] 1. Significantly improved energy density: Nitrogen / boron doping introduces weak pseudocapacitance, and the overall energy density can reach 50~55Wh / kg, which is more than 30% higher than that of SO5 biomass carbon electrode and 6~7 times that of traditional double-layer capacitors.

[0025] 2. Significantly reduced gas generation rate under high voltage: Doping modification optimizes the surface functional groups of carbon materials, and the gas generation rate under 3.5V high voltage is reduced by more than 50% compared with undoped carbon, which greatly improves the operational safety and stability of the device.

[0026] 3. Excellent interface performance: The carbon nano-anchoring layer increases the bonding force between the active layer and the current collector by more than 3 times, with a cycle life of ≥150,000 cycles and a capacity retention rate of ≥92%.

[0027] 4. 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 output high voltage above 800V without the need for external series and parallel connections, reducing system costs by more than 40%.

[0028] 5. Mature technology and easy mass production: All processes are existing mature coating processes that can be directly connected to existing electrode production lines and are 100% compatible with the complete set of processes of S01-S05, without the need for additional equipment. Attached Figure Description

[0029] Figure 1 This is a schematic cross-sectional view of the doped porous carbon electrode described in this invention.

[0030] Figure 2 This is a schematic diagram of the planar structure of the doped porous carbon electrode described in this invention;

[0031] Figure 3 This is a schematic diagram illustrating the application of the doped porous carbon electrode described in this invention in a high-voltage series energy storage device.

[0032] Explanation of reference numerals in the attached figures (100% following Figure S05):

[0033] 1 - Metal-based composite copper-aluminum foil current collector, 2 - Copper layer, 3 - Aluminum layer, 4 - Carbon nano-anchoring layer, 5 - Nitrogen-doped hard carbon negative electrode active layer, 6 - Boron-doped activated carbon positive electrode active layer, 7 - Insulating edge area, 8 - Electrode active area, 9 - Multilayer series cell body, 10 - Doped porous carbon electrode, 11 - Separator, 12 - Stepped insulating edge sealing layer, 13 - Liquid injection hole. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to specific embodiments.

[0035] Example 1

[0036] The doped porous carbon electrode described in this embodiment uses a 20μm thick copper-aluminum composite foil current collector, with the copper layer and aluminum layer each 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 nitrogen-doped hard carbon anode (nitrogen doping amount 3at%), and the aluminum layer side is coated with a 120μm thick boron-doped activated carbon cathode (boron doping amount 2at%); the electrode size is 300mm×200mm, with a 2mm wide insulating edge reserved around the perimeter.

[0037] The preparation method is as follows:

[0038] 1. Preparation of doped porous carbon: Coconut shell precursor and urea were mixed at a ratio of 4:1, carbonized at 600℃ for 1 hour, and activated with KOH for 2 hours to obtain nitrogen-doped hard carbon with a specific surface area of ​​[missing information]. ; Coconut shell precursor and boric acid are mixed at a ratio of 4:1, and boron-doped activated carbon is obtained using the same process, with a specific surface area of ;

[0039] 2. Anchoring layer coating: Carbon nanotube dispersion is coated on both sides of the current collector and dried at 100℃ to form an 80nm anchoring layer;

[0040] 3. Active layer coating: Prepare negative and positive electrode slurries separately, and coat them sequentially on both sides of the current collector;

[0041] 4. Drying and rolling: Vacuum drying at 120℃ for 12h, rolling at 12MPa, and cutting to obtain the finished electrode.

[0042] Application effect:

[0043] The electrode was used in a 350V high-voltage hybrid energy storage device with 100 layers connected in series. The overall energy density was 52Wh / kg. After 150,000 cycles, the capacity retention rate was 93.5%. The gas production rate at 3.5V high voltage was 56% lower than that of undoped carbon. There was no active layer shedding or increase in internal resistance.

[0044] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A doped porous carbon electrode, characterized in that... It includes a metal-based composite copper-aluminum foil current collector, a carbon nanotube anchoring layer, and a doped 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 doped porous carbon active layer is coated on the surface of the carbon nano-anchor layer, the copper layer side is a nitrogen-doped hard carbon negative electrode active layer, and the aluminum layer side is a boron-doped activated carbon positive electrode active layer, forming a dual-sided heterogeneous composite electrode.

2. The doped porous carbon electrode according to claim 1, characterized in that... The nitrogen doping amount of the doped porous carbon active layer is 2~5 at%, the boron doping amount is 1~3 at%, and the specific surface area is... The pore size distribution is 2~50nm.

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

4. The doped porous carbon electrode according to claim 1, characterized in that... The thickness of the doped porous carbon active layer is 50~200μm, and the compaction density is... It is compatible with high-voltage organic electrolytes with voltage windows of 3.5V and above.

5. The doped porous carbon 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.

6. A method for preparing a doped porous carbon electrode as described in any one of claims 1-5, characterized in that... This includes the following steps: S1 Doped Porous Carbon Preparation: Biomass carbon precursors are mixed with dopants, and after carbonization and activation, nitrogen-doped hard carbon powder and boron-doped activated carbon powder are prepared. S2 Anchoring Layer Coating: Carbon nanotubes or graphene oxide dispersion 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: Nitrogen-doped hard carbon anode slurry and boron-doped activated carbon cathode slurry are prepared respectively and coated sequentially on the anchoring layer surfaces 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 doped porous carbon electrode of a preset size.

7. The preparation method according to claim 6, characterized in that... In step S1, the dopant is urea, melamine or boric acid, the carbonization temperature is 500~700℃, the activation temperature is 700~900℃, and the activation time is 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 negative electrode slurry and the positive electrode slurry is 40~60wt%, and the coating speed is 5~20m / min; in step S4, the roller pressure is 5~15MPa.

10. The application of a doped porous carbon electrode as described in any one of claims 1-5 in a high-voltage series hybrid energy storage device, characterized in that... The energy storage device has a 50-380 layer internal series structure, a rated operating voltage of ≥800V, uses 16V high-voltage organic electrolyte, and has a cycle life of ≥150,000 cycles.

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