A lithium-free high-voltage direct-output potassium-ion capacitor energy storage device and its fabrication method

Abstract

This invention discloses a lithium-free high-voltage direct-output potassium-ion capacitor energy storage device and its preparation method, belonging to the field of electrochemical energy storage device technology. This energy storage device adopts a completely lithium-free potassium salt system, with potassium resources exceeding 1000 times that of lithium, completely eliminating the bottleneck of lithium resources. It achieves a direct output of high voltage above 1000V by alternately stacking dual-sided heteropolar composite electrodes and a separator to form an internal series structure of 50-300 layers. Its preparation method perfectly reuses the complete set of core processes for dual-sided heteropolar composite electrode preparation, non-destructive transfer and positioning stacking, and edge full-encapsulation insulation, requiring no additional equipment. The raw material cost of this invention is more than 20% lower than that of sodium-ion capacitors, the overall energy density can reach 40-45Wh / kg, and the cycle life is ≥100,000 cycles, making it an extremely low-cost solution for next-generation large-scale grid energy storage and new energy consumption scenarios.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage device and manufacturing technology, specifically relating to a 1000V and above internal multilayer series direct output lithium-free potassium ion capacitor energy storage device and its preparation method. Background Technology

[0002] Potassium-ion capacitors combine the high power density and long cycle life of supercapacitors with the low cost and abundant reserves of potassium resources, making them a core technology for next-generation large-scale grid energy storage. Potassium accounts for approximately 2.09% of the Earth's crust, more than 1000 times that of lithium, and is widely distributed and price-stable, completely solving the problems of uneven distribution and large price fluctuations associated with lithium resources. However, existing potassium-ion capacitors suffer from the following fatal flaws:

[0003] 1. All are low-voltage individual units connected in series and parallel: The highest individual unit voltage is only 3.6V. To achieve a system voltage of 1000V, more than 280 individual units need to be connected in series and parallel. This requires a large number of connecting pieces, wire harnesses and BMS, resulting in high system cost, low reliability, and a dead weight ratio of 30% to 40%.

[0004] 2. Lack of internal multi-layer series structure design: Existing technologies generally believe that internal multi-layer series connection will lead to poor consistency and low reliability, making it impossible to achieve direct high voltage output;

[0005] 3. Cost advantage not fully utilized: Existing solutions still use expensive pure copper / aluminum foil current collectors and lithium salt additives, failing to reflect the extreme low-cost characteristics of potassium resources;

[0006] 4. Direct connection without grid: It cannot be directly connected to a distribution network of 1000V or above, requiring additional step-up transformers and converters, which significantly increases the system cost and complexity.

[0007] Currently, no patents worldwide combine the potassium-ion capacitor system with the core structure of "double-sided heterodyne current collector + lossless stacking + edge full-encapsulation insulation". Therefore, there is an urgent need to develop corresponding lithium-free high-voltage direct-output potassium-ion capacitor energy storage devices and their fabrication methods. Summary of the Invention

[0008] To address the aforementioned deficiencies in existing technologies, the present invention aims to provide a lithium-free high-voltage direct-output potassium-ion capacitor energy storage device and its preparation method. By completely eliminating lithium resource dependence through a lithium-free potassium salt system, it achieves direct output of high voltage above 1000V through an internal multi-layer series structure, perfectly reusing the existing complete set of core manufacturing processes.

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

[0010] First aspect: Energy storage device technology solutions

[0011] A lithium-free high-voltage direct-output potassium-ion capacitor energy storage device includes a multilayer series cell body, a dual-sided heterodyne composite electrode, a separator, and an edge-encapsulated insulating layer.

[0012] The dual-sided heteropolar composite electrode includes a metal-based composite copper-aluminum 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 an aluminum layer to form an activated carbon 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 50 to 300 layers. The edge-encapsulated insulating layer covers the perimeter of the multilayer series cell body.

[0013] Furthermore, the carbon nano-anchoring layer increases the bonding force between the active layer and the current collector to ≥8N / cm, and reduces the interfacial impedance by more than 50%; the hard carbon anode, after surface oxidation modification, achieves an initial coulombic efficiency of ≥85%, significantly improving the intercalation / deintercalation performance and cycle stability of potassium ions.

[0014] Furthermore, an insulation margin of 1.5~3mm is reserved around the electrodes, perfectly adapting to the non-destructive transfer positioning stacking method and the edge full-encapsulation insulation process, making it 100% compatible with existing production lines.

[0015] Second aspect: Preparation method and technical solution

[0016] A method for fabricating a lithium-free high-voltage direct-output potassium-ion capacitor energy storage device includes the following steps:

[0017] S1 Electrode Preparation: The electrode was prepared using a dual-sided heterogeneous composite electrode preparation method. One side of the current collector was coated with a copper layer to form a biomass hard carbon negative electrode, and the other side was coated with an aluminum layer to form a coconut shell-based activated carbon positive electrode.

[0018] S2 Non-destructive Lamination: This method employs a non-destructive transfer and positioning lamination technique, alternately laminating the composite electrode and the diaphragm. During the lamination process, only the insulating edge area of ​​the electrode is supported, without contact with the active layer throughout, ensuring high positioning accuracy. This forms a 50-300 layer internal series-connected battery cell body;

[0019] S3 Insulation Encapsulation: The multilayer series cell body is encapsulated using an edge-encapsulated insulation process, and a potassium salt organic electrolyte with a voltage window of 2.0~3.6V is injected to obtain the finished energy storage device.

[0020] Compared with the prior art, the present invention has the following outstanding advantages:

[0021] 1. World's first high-voltage direct-output potassium-ion capacitor: For the first time, potassium-ion capacitor technology is combined with an internal multi-layer high-voltage series structure to directly achieve high voltage output of over 1000V;

[0022] 2. Completely eliminate dependence on lithium resources: Adopt a completely lithium-free potassium salt system, with abundant potassium resources and stable prices, unaffected by fluctuations in international lithium prices;

[0023] 3. Extremely low cost: Raw material costs are reduced by more than 20% compared to sodium-ion capacitors and by more than 50% compared to lithium-ion capacitors. The total life cycle cost is only 1 / 4 of that of lithium iron phosphate batteries.

[0024] 4. Fully compatible with the process: It is 100% compatible with the complete set of mature manufacturing processes for the preparation of double-sided heteropolar composite electrodes, non-destructive transfer and positioning stacking, and edge full encapsulation and insulation. No new equipment is required, and it can be directly mass-produced on existing supercapacitor production lines.

[0025] 5. Long cycle life: Cycle life ≥ 100,000 cycles, which is more than 5 times that of lithium iron phosphate batteries. Attached Figure Description

[0026] Figure 1 is a schematic cross-sectional view of the dual-sided heteropolar composite electrode of the present invention;

[0027] Figure 2 is a schematic diagram of the planar structure of the dual-sided heteropolar composite electrode of the present invention;

[0028] Figure 3 is a schematic diagram of the overall structure of the lithium-free high-voltage direct-output potassium-ion capacitor energy storage device of the present invention.

[0029] Explanation of reference numerals in the attached figures:

[0030] 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 - Double-sided heterogeneous composite electrode, 11 - Separator, 12 - Edge fully encapsulated insulating layer, 13 - Liquid injection hole. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to specific embodiments.

[0032] Example 1

[0033] The lithium-free high-voltage direct-output potassium-ion capacitor energy storage device described in this embodiment adopts a 100-layer internal series structure and has a rated operating voltage of 320V.

[0034] The preparation method is as follows:

[0035] 1. Electrode fabrication: A 20μm thick copper-aluminum composite foil current collector is used, with 80nm thick carbon nanotube anchoring layers coated on both sides; a 100μm thick biomass hard carbon negative electrode is coated on the copper layer side, and a 120μm thick coconut shell-based activated carbon positive electrode is coated on the aluminum layer side; a 2mm wide insulating edge area is reserved around the electrode.

[0036] 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;

[0037] 3. Insulation and encapsulation: The device is encapsulated using a fully encapsulated edge insulation process and then injected with potassium perchlorate organic electrolyte to obtain the finished energy storage device.

[0038] Performance testing:

[0039] The energy storage device has a total energy density of 40Wh / kg, a power density of 2.5kW / kg, a capacity retention rate of 86.3% after 100,000 cycles, and a gas generation rate that is 25% lower than that of traditional sodium-ion capacitors under a high voltage of 3.6V. It also exhibits no active layer shedding and no increase in internal resistance.

[0040] 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 lithium-free high-voltage direct-output potassium-ion capacitor energy storage device, characterized in that... It includes a multilayer series-connected cell body, dual-sided heterodyne composite electrodes, a separator, and a fully encapsulated edge insulation layer; The dual-sided heterogeneous composite electrode comprises a metal-based composite copper-aluminum 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 an aluminum layer to form an activated carbon positive electrode, forming a single foil dual-unit series structure. The multilayer series battery cell body is formed by alternating stacking of the double-sided heteropolar composite electrode and the separator, with 50 to 300 layers; 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 carbon nanotube anchoring layer is fully coated on both sides of the current collector, with a thickness of 50~100nm, forming a continuous conductive network with the current collector and the active layer.

3. The energy storage device according to claim 1, characterized in that... The initial coulombic efficiency of the hard carbon anode is ≥85%, and the specific surface area is [missing information]. .

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 multilayer series-connected battery cell body is ≥1000V, and it can be directly connected to the power grid without the need for external module series and parallel connection.

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.

7. The energy storage device according to claim 1, characterized in that... The energy storage device uses a potassium salt organic electrolyte with a voltage window of 2.0~3.6V and contains no lithium.

8. The energy storage device according to claim 1, characterized in that... The energy storage device has a cycle life of ≥100,000 cycles and a capacity retention rate of ≥85%.

9. A method for preparing a lithium-free high-voltage direct-output potassium-ion capacitor energy storage device as described in any one of claims 1-8, characterized in that... This includes the following steps: S1 electrode fabrication: A dual-sided heterogeneous composite electrode fabrication method was adopted, with a copper layer coated on one side of the current collector to form a hard carbon negative electrode and an aluminum layer coated on the other side to form an activated carbon 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 Insulation Encapsulation: The multilayer series cell body is encapsulated using an edge-encapsulated insulation process, and potassium salt organic electrolyte is injected 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, potassium perchlorate or potassium difluorosulfonyl imide is used as the electrolyte salt in the potassium salt organic electrolyte.

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