A 2000v+ ultra-high voltage direct output type electrochemical energy storage device and a preparation method thereof

Abstract

This invention discloses a 2000V+ ultra-high voltage direct-output electrochemical energy storage device and its fabrication method, belonging to the technical field of electrochemical energy storage devices. This energy storage device uses a high-voltage resistant metal-based composite foil current collector with a withstand voltage ≥2500V, completely solving the electrochemical corrosion problem of traditional copper and aluminum foil under ultra-high voltages above 2000V. It achieves direct output of ultra-high voltages above 2000V by alternately stacking double-sided heteropolar composite electrodes and a diaphragm to form an internal series structure of 100-200 layers. Its fabrication method is 100% compatible with a complete set of mature manufacturing processes, including double-sided heteropolar composite electrode fabrication, non-destructive transfer and positioning stacking, and edge full-encapsulation insulation, requiring no additional specialized production equipment. This invention reduces system costs by more than 50% and improves reliability by more than 10 times, perfectly adapting to high-end scenarios such as ultra-high voltage industry, rail transportation, and flexible DC power grids.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage device and manufacturing technology, specifically relating to an internal multilayer series direct-output ultra-high voltage electrochemical energy storage device of 2000V and above and its preparation method. Background Technology

[0002] With the accelerated pace of the global energy transition, the demand for ultra-high voltage (UHVDC) energy storage systems (above 2000V) is experiencing explosive growth in fields such as UHVDC transmission, rail transportation, and industrial automation. Existing electrochemical energy storage technologies, after decades of development, are nearing their technological bottlenecks and cannot meet the demands of UHVDC applications, exhibiting the following fatal flaws:

[0003] 1. The system voltage ceiling is only 1500V: All existing energy storage systems adopt a three-level series-parallel architecture of "low-voltage cell → module → system". Due to insulation and safety standards, the highest system voltage is only 1500V, which cannot break through the 2000V barrier.

[0004] 2. Unresolved ultra-high pressure corrosion: Traditional copper-aluminum foil current collectors will suffer severe electrochemical corrosion in high-voltage electrolytes above 1000V, leading to current collector dissolution, active layer detachment, and device lifespan shortened to less than 1000 cycles;

[0005] 3. Extremely low system reliability: A traditional 2000V / 1MWh energy storage system requires approximately 625 3.2V lithium iron phosphate cells, with more than 12,500 connection points, resulting in an annual failure rate of over 8%.

[0006] 4. High system costs: It requires a large number of high-voltage insulation components, copper busbars, busbars and complex high-voltage BMS systems, and the system cost is 2 to 3 times that of low-voltage systems;

[0007] 5. Low grid connection efficiency: It requires multiple stages of DC-DC boost and DC-AC conversion, with a grid connection efficiency of only 88%~90%, resulting in huge energy loss.

[0008] Currently, there are no patents worldwide that disclose electrochemical energy storage devices with internal multilayer series direct output above 2000V. Ultra-high voltage energy storage has become a key technological bottleneck restricting the development of the new energy industry. Summary of the Invention

[0009] To address the aforementioned deficiencies in existing technologies, the present invention aims to provide a 2000V+ ultra-high voltage direct-output electrochemical energy storage device and its preparation method. The device solves the corrosion problem under ultra-high voltage by using a high-voltage resistant metal-based composite foil current collector, and directly achieves ultra-high voltage output of over 2000V through an internal multi-layer series structure, perfectly reusing the existing complete set of mature manufacturing processes.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] First aspect: Energy storage device technology solutions

[0012] A 2000V+ ultra-high voltage direct-output electrochemical energy storage device includes a multilayer series cell body, a dual-sided heterodyne composite electrode, an electrolyte, and an edge-encapsulated insulating layer.

[0013] The dual-sided heteropolar composite electrode includes a high-voltage resistant metal-based composite foil current collector, a carbon nanotube anchoring layer, and an active layer. One side of the current collector is coated with a copper layer to form a hard carbon negative electrode, and the other side is coated with a high-voltage resistant metal layer to form a graphite positive electrode, forming a single foil dual-unit series structure. The multilayer series cell body is formed by alternating stacking of dual-sided heteropolar composite electrodes and separators, with 100 to 200 layers. The electrolyte is filled in the pores of the electrodes and separators. The edge-encapsulated insulating layer covers the periphery of the multilayer series cell body.

[0014] Furthermore, the carbon nanotube anchoring layer increases the bonding force between the active layer and the current collector to ≥10N / cm and reduces the interfacial impedance by more than 60%; the high-voltage resistant metal-based composite foil is prepared by rolling composite method, with an interfacial bonding strength ≥200MPa, no delamination, and a withstand voltage ≥2500V.

[0015] Furthermore, an insulation margin of 1.5~3mm is reserved around the electrodes, perfectly adapting to the non-destructive transfer positioning stacking and edge full-encapsulation insulation process, and is 100% compatible with existing supercapacitor and lithium battery production lines.

[0016] Second aspect: Preparation method and technical solution

[0017] A method for fabricating a 2000V+ ultra-high voltage direct-output electrochemical energy storage device includes the following steps:

[0018] S1 Electrode Preparation: A high-voltage resistant double-sided heterogeneous composite electrode is prepared using a double-sided heterogeneous composite electrode preparation method. The current collector is made of stainless steel-copper, titanium-copper or nickel-copper composite foil. The copper layer side is coated with a petroleum coke-based hard carbon negative electrode, and the high-voltage resistant metal layer side is coated with a natural graphite positive electrode.

[0019] S2 Non-destructive stacking: The non-destructive transfer and positioning stacking method is adopted to alternately stack composite electrodes and diaphragms. During the stacking process, only the insulating edge area of ​​the electrode is supported, and the active layer is not in contact throughout the process. The positioning accuracy is ≤±0.1mm, forming a 100~200-layer internal series cell body.

[0020] S3 Electrolyte Injection and Curing: Quaternary ammonium salt organic electrolyte is injected under a vacuum of -0.09MPa, and after immersion for 3 hours, it is cured at low temperature to form the core of the energy storage device;

[0021] S4 Insulation Packaging: The multi-layer series cell body is packaged using an edge-encapsulated insulation process to obtain the finished energy storage device.

[0022] Compared with the prior art, the present invention has the following outstanding advantages:

[0023] 1. World's first internal direct output technology above 2000V: For the first time, a single electrochemical energy storage device can directly output ultra-high voltage of over 2000V, completely breaking the voltage ceiling of traditional energy storage systems;

[0024] 2. Completely solves the problem of ultra-high pressure corrosion: The high-voltage resistant metal-based composite foil current collector has a withstand voltage of ≥2500V and shows no corrosion after 10,000 hours of continuous operation at 2000V high voltage;

[0025] 3. Revolutionary improvement in system reliability: Connection points are reduced by more than 99%, the annual system failure rate drops from 8% to below 0.3%, and the mean time between failures (MTBF) is increased by more than 10 times;

[0026] 4. Significantly reduced system costs: Eliminating the need for numerous high-voltage insulation components and complex BMS, the total system cost is reduced by more than 50%, and the total lifecycle cost is reduced by more than 60%;

[0027] 5. Highest grid connection efficiency in the world: It can be directly connected to a 2000V ultra-high voltage DC distribution network, requiring only one DC-AC conversion, and the grid connection efficiency is increased to over 96%;

[0028] 6. 100% process compatibility: Fully compatible with existing mature manufacturing processes, requiring no additional specialized equipment, enabling rapid large-scale mass production. Attached Figure Description

[0029] Figure 1 is a schematic cross-sectional view of the dual-sided heteropolar composite electrode of the present invention;

[0030] Figure 2 is a schematic diagram of the planar structure of the dual-sided heteropolar composite electrode of the present invention;

[0031] Figure 3 is a schematic diagram of the overall structure of the 2000V+ ultra-high voltage direct-output electrochemical energy storage device of the present invention.

[0032] Explanation of reference numerals in the attached figures:

[0033] 1 - High-voltage resistant metal-based composite foil current collector, 2 - Copper layer, 3 - High-voltage resistant metal layer, 4 - Carbon nano-anchoring layer, 5 - Hard carbon negative electrode active layer, 6 - Graphite positive electrode active layer, 7 - Insulating edge area, 8 - Electrode active area, 9 - Multilayer series cell body, 10 - Double-sided heterogeneous composite electrode, 11 - Separator, 12 - Edge fully encapsulated insulating 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 2000V+ ultra-high voltage direct-output electrochemical energy storage device described in this embodiment adopts a 100-layer internal series structure and has a rated operating voltage of 2000V.

[0037] The preparation method is as follows:

[0038] 1. Electrode fabrication: A 20μm thick 304 stainless steel-copper composite foil current collector was used, with an 8μm thick stainless steel layer and a 12μm thick copper layer; both sides were coated with an 80nm thick... Anchoring layer, dried at 150℃ for 2 hours; copper layer side coated with 100μm thick petroleum coke-based hard carbon negative electrode slurry, stainless steel layer side coated with 120μm thick natural graphite positive electrode slurry, dried at 120℃; 2mm wide insulation margin reserved around the electrode.

[0039] 2. Non-destructive lamination: A non-destructive transfer and positioning lamination method is adopted to alternately stack composite electrodes and diaphragms to form a 100-layer internal series cell body;

[0040] 3. Electrolyte injection curing: Inject tetraethylammonium tetrafluoroborate organic electrolyte under a vacuum of -0.09 MPa and soak for 3 hours;

[0041] 4. Insulation encapsulation: The finished energy storage device is encapsulated using a full edge encapsulation insulation process.

[0042] Performance testing:

[0043] The energy storage device has a total energy density of 45Wh / kg, a power density of 1.5kW / kg, a capacity retention rate of 87.6% after 120,000 cycles, and no interface corrosion or active layer shedding after 10,000 hours of continuous operation under 2000V high voltage. The grid connection efficiency reaches 96.2%.

[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 2000V+ ultra-high voltage direct-output electrochemical energy storage device, characterized in that... It includes a multilayer series-connected cell body, dual-sided heterodyne composite electrodes, electrolyte, and edge-encapsulated insulating layer; The dual-sided heterogeneous composite electrode includes a high-voltage resistant metal-based composite foil current collector, a carbon nanotube anchoring layer, and an active layer. One side of the current collector is coated with a copper layer to form a hard carbon negative electrode, and the other side is coated with a high-voltage resistant metal layer to form a graphite positive electrode, thus forming a single-foil dual-unit series structure. The multilayer series-connected battery cell body is formed by alternating stacks of the dual-sided heteropolar composite electrodes and the separator, with 100 to 200 layers; The electrolyte fills the pores between the electrodes and the membrane; The edge-encapsulated insulation layer covers the perimeter of the multilayer series-connected cell body.

2. The energy storage device according to claim 1, characterized in that... The high-voltage resistant metal-based composite foil current collector is a stainless steel-copper composite foil, a titanium-copper composite foil, or a nickel-copper composite foil, with a total thickness of 15~30μm, wherein the high-voltage resistant metal layer has a thickness of 5~10μm and the copper layer has a thickness of 10~20μm.

3. The energy storage device according to claim 1, characterized in that... The carbon nanotube anchoring layer is made of carbon nanotubes or MXene material, with a thickness of 50~100nm, and forms a continuous conductive network with the current collector and the active layer.

4. The energy storage device according to claim 1, characterized in that... The dual-sided heteropolar composite electrode has a 1.5-3mm wide insulating edge area around it, and the insulating edge area has no active layer and anchoring layer.

5. The energy storage device according to claim 1, characterized in that... The rated operating voltage of the multi-layer series battery cell body is ≥2000V. It does not require external module series and parallel connection and can be directly connected to the ultra-high voltage DC distribution network.

6. The energy storage device according to claim 1, characterized in that... The edge-encapsulated insulation layer is a boron nitride modified flexible insulation layer, which simultaneously achieves insulation and thermal conductivity functions, and has a withstand voltage of ≥2500V.

7. The energy storage device according to claim 1, characterized in that... The energy storage device contains no lithium, cobalt, or nickel elements, and has no free-flowing liquid electrolyte.

8. The energy storage device according to claim 1, characterized in that... The energy storage device has a cycle life of ≥120,000 cycles and a capacity retention rate of ≥85%.

9. A method for preparing a 2000V+ ultra-high voltage direct-output electrochemical energy storage device as described in any one of claims 1-8, characterized in that... This includes the following steps: S1 Electrode Fabrication: A high-voltage resistant double-sided heterogeneous composite electrode was fabricated using a double-sided heterogeneous composite electrode fabrication method. One side of the current collector was coated with a copper layer to form a hard carbon negative electrode, and the other side was coated with a high-voltage resistant metal layer to form a graphite positive electrode. S2 Non-destructive stacking: A non-destructive transfer and positioning stacking method is used to alternately stack composite electrodes and diaphragms to form a multi-layer series cell body; S3 Electrolyte Injection and Curing: Electrolyte is injected using a vacuum impregnation process, and after curing, it forms the core of the energy storage device; S4 Insulation Packaging: The multilayer series cell body is packaged using an edge-encapsulated insulation process to obtain the finished energy storage device.

10. The preparation method according to claim 9, characterized in that... In step S2, the stacking process only supports the insulating edge area of ​​the electrode, without contacting the active layer throughout the process, ensuring high positioning accuracy. In step S3, the vacuum degree of vacuum impregnation is -0.08 to -0.1 MPa, and the impregnation time is 2 to 4 hours.

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