Lithium-free high-voltage direct-output sodium ion capacitor energy storage device and preparation method thereof

Abstract

The invention discloses a lithium-free high-voltage direct-output sodium ion capacitor energy storage device and a preparation method thereof, and belongs to the technical field of electrochemical energy storage devices. The energy storage device adopts a completely lithium-free system, a 50-380-layer internal series connection structure is formed through alternate lamination of double-side heteropole composite electrodes and diaphragms, direct output of high voltage of 1200 V or above is directly achieved, and direct power grid direct hanging can be achieved. The preparation method perfectly reuses the whole set of core processes of S01 to S03, and does not need to add new equipment. The energy density of the whole pack can reach 35-40 Wh / kg, the cost of raw materials is reduced by 40% or above compared with that of a lithium ion capacitor, dependence on lithium resources is thoroughly eliminated, the cycle life is longer than or equal to 120 thousand times, and the requirements of scenes such as power grid area energy storage, new energy grid connection and industrial standby power supplies are perfectly met.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage device and manufacturing technology, specifically relating to a 1200V and above internal multilayer series direct output lithium-free sodium ion capacitor energy storage device and its preparation method. Background Technology

[0002] Sodium-ion capacitors combine the high power, long cycle life, and lithium-free, low-cost advantages of supercapacitors, making them a core technology for next-generation grid energy storage. However, existing sodium-ion capacitors suffer from the following fatal flaws:

[0003] 1. All are low-voltage individual units connected in series and parallel: The highest module voltage does not exceed 100V, requiring 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. Not completely lithium-free: Most existing sodium-ion capacitors still use lithium-containing additives or lithium-containing current collector coatings, and have not completely gotten rid of dependence on lithium 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, there are no patents worldwide that combine a completely lithium-free sodium-ion capacitor system with a 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 sodium-ion capacitor energy storage devices and their fabrication methods. Summary of the Invention

[0008] To address the aforementioned shortcomings of existing technologies, the present invention aims to provide a lithium-free high-voltage direct-output sodium-ion capacitor energy storage device and its preparation method. By completely eliminating the dependence on lithium resources through a lithium-free system, it directly achieves high voltage output of over 1200V through an internal multi-layer series structure, perfectly reusing the existing complete set of core manufacturing processes, and significantly reducing system costs.

[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 sodium-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 380 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 ≥88%, significantly improving the insertion / extraction performance of sodium ions.

[0014] Furthermore, an insulating edge area of ​​1.5~3mm is reserved around the electrodes, which is perfectly compatible with SO2 non-destructive lamination and SO3 edge full encapsulation processes, and is 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 sodium-ion capacitor energy storage device includes the following steps:

[0017] S1 electrode preparation: A double-sided heterogeneous composite electrode was prepared using the S01 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 stacking: Using the non-destructive transfer and positioning stacking method of S02, the composite electrode and the diaphragm are stacked alternately. 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 50~380-layer internal series cell body.

[0019] S3 Insulation Packaging: The multilayer series cell body is packaged using the S03 edge full-encapsulation insulation process, and sodium salt organic electrolyte with a voltage window of 1.2~3.6V 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 completely lithium-free high-voltage direct-output sodium-ion capacitor: Completely eliminates dependence on lithium resources, unaffected by lithium price fluctuations, and reduces raw material costs by more than 40% compared to lithium-ion capacitors;

[0022] 2. Highest voltage output in the world: 380 layers of internal series connection directly achieve high voltage of 1200V and above, which can be directly connected to distribution networks below 10kV without the need for external step-up equipment, reducing system costs by more than 50%;

[0023] 3. Fully compatible with the process: 100% compatible with the complete manufacturing process of S01-S03, requiring no additional equipment, and can be directly mass-produced on existing supercapacitor production lines;

[0024] 4. Ultra-long cycle life: Cycle life ≥ 120,000 cycles, which is more than 6 times that of lithium iron phosphate batteries, and the total life cycle cost is only 1 / 4 of that of lithium iron phosphate batteries;

[0025] 5. Extremely high safety: It adopts a lithium-free system and organic electrolyte, eliminating the risk of thermal runaway and greatly improving operational safety. 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 sodium-ion capacitor energy storage device of the present invention.

[0029] Explanation of reference numerals in the accompanying drawings (completely consistent with the invention, 100% following the figures in S05):

[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 sodium-ion capacitor energy storage device described in this embodiment adopts a 200-layer internal series structure and has a rated operating voltage of 720V.

[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: Using the non-destructive transfer and positioning lamination method of SO2, composite electrodes and separators are alternately laminated to form a 200-layer internal series cell body;

[0037] 3. Insulation and encapsulation: The device is encapsulated using the SO3 edge full-encapsulation insulation process and injected with sodium perchlorate organic electrolyte to obtain the finished energy storage device.

[0038] Performance testing:

[0039] The energy storage device has a total energy density of 38Wh / kg, a power density of 3kW / kg, a capacity retention rate of 91.7% after 120,000 cycles, and a gas generation rate that is 40% 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 sodium-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-connected battery cell body is formed by alternating stacking of the dual-sided heteropolar composite electrodes and the separator, with 50 to 380 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 ≥88%, 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 ≥1200V, 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 sodium salt organic electrolyte with a voltage window of 1.2~3.6V 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 ≥120,000 cycles and a capacity retention rate of ≥90%.

9. A method for preparing a lithium-free high-voltage direct-output sodium-ion capacitor energy storage device as described in any one of claims 1-8, characterized in that... This includes the following steps: S1 electrode preparation: A double-sided heterogeneous composite electrode was prepared using the S01 method, 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 Lamination: Using the S02 non-destructive transfer and positioning lamination method, composite electrodes and separators are alternately laminated to form a multilayer series cell body; S3 Insulation Encapsulation: The multilayer series cell body is encapsulated using the S03 edge full-encapsulation insulation process, and sodium 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, sodium perchlorate or sodium difluorosulfonamide is used as the sodium salt in the organic electrolyte.

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