A sulfide composite electrolyte high-voltage energy storage device and a preparation method thereof

Abstract

The application discloses a sulfide composite electrolyte high-voltage 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 sulfide-polymer composite electrolyte, completely solves the air sensitivity and brittleness problems of a pure sulfide solid electrolyte, and the pressure resistance of a single unit is increased to above 18V; a 50-120-layer internal series structure is formed by alternately stacking a double-side heteropolar composite electrode and a diaphragm, and direct high-voltage direct output above 1000V is realized. The preparation method adopts a vacuum infiltration + low-temperature hot pressing process, perfectly reuses a double-side heteropolar composite electrode preparation, lossless switching and positioning of a stacked sheet, and a full set of core processes of edge full encapsulation insulation, and does not need to add new equipment. The whole package energy density can reach 70-75Wh / kg, the capacity retention rate is greater than or equal to 80% at an ultra-low temperature of-40 DEG C, and the application perfectly adapts to high-end energy storage scenes such as super-fast charging, ultra-low temperature and high safety.

Description

Technical Field

[0002] 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 sulfide composite electrolyte high-voltage energy storage device and its preparation method. Background Technology

[0003] Sulfide solid electrolytes have the highest known room-temperature ionic conductivity (up to 100%). The above-mentioned excellent mechanical properties and wide voltage window make it considered the ultimate technological route for achieving high energy density and high safety solid-state energy storage. However, existing sulfide solid-state energy storage technologies suffer from the following fatal flaws:

[0004] 1. The inherent defects of pure sulfides cannot be overcome: they will rapidly hydrolyze to produce toxic hydrogen sulfide gas when exposed to air, and are extremely brittle, easily cracking during stacking and cycling, leading to internal short circuits, resulting in a mass production yield of less than 20%;

[0005] 2. All are low-voltage individual units connected in series and parallel: The highest individual unit voltage is only 4.2V. To achieve a system voltage of 1000V, more than 240 individual units need to be connected in series and parallel. The system has high cost, low reliability, and a dead weight ratio of more than 40%.

[0006] 3. Lack of internal multi-layer series adapter design: Existing technologies all believe that internal multi-layer series connection will lead to poor electrolyte interface contact and lithium dendrite penetration, making it impossible to achieve high voltage direct output;

[0007] 4. Poor performance at ultra-low temperatures: The ionic conductivity of traditional liquid electrolytes drops sharply below -20℃, which cannot meet the application requirements of extremely cold regions in the north and high-altitude regions;

[0008] 5. Extremely poor process compatibility: New dedicated equipment for sulfide synthesis, ultra-thin electrolyte coating, and high-temperature hot pressing is required, with the cost of modifying a single production line exceeding 200 million yuan.

[0009] Currently, no patents worldwide combine sulfide composite electrolytes with the core structure of "dual-sided heteropolar current collectors + lossless stacking + edge full-encapsulation insulation". Therefore, there is an urgent need to develop corresponding sulfide composite electrolyte high-voltage energy storage devices and their preparation methods. Summary of the Invention

[0010] To address the aforementioned deficiencies in existing technologies, the present invention aims to provide a sulfide composite electrolyte high-voltage energy storage device and its preparation method. By using a sulfide-polymer composite electrolyte, the air sensitivity and brittleness issues of pure sulfides are solved. Through an internal multi-layer series structure, high voltage output of over 1000V is directly achieved, perfectly reusing the existing complete set of core manufacturing processes.

[0011] To achieve the above objectives, the present invention adopts the following technical solution:

[0012] First aspect: Energy storage device technology solutions

[0013] A high-voltage energy storage device with a sulfide composite electrolyte includes a multilayer series cell body, a dual-sided heterodyne composite electrode, a sulfide-polymer composite electrolyte, and an edge-encapsulated insulating layer.

[0014] 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 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 50 to 120 layers. A sulfide-polymer composite electrolyte fills the pores of the electrodes and separators. An edge-encapsulated insulating layer covers the periphery of the multilayer series cell body.

[0015] 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 particle size of the powder is 200~800nm, and the ionic conductivity of the composite electrolyte is... It has a thermal decomposition temperature of ≥200℃ and air stability that is more than 100 times higher than that of pure sulfides.

[0016] Furthermore, an insulating edge area of ​​1.5~3mm is reserved around the electrodes, which perfectly adapts to the non-destructive positioning stacking and edge full encapsulation process, and is 100% compatible with existing production lines.

[0017] Second aspect: Preparation method and technical solution

[0018] A method for preparing a sulfide composite electrolyte high-voltage energy storage device includes the following steps:

[0019] 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 petroleum coke-based hard carbon negative electrode, and the other side was coated with an aluminum layer to form a natural graphite positive electrode.

[0020] 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 50~120-layer internal series cell body.

[0021] S3 composite electrolyte curing: Injection under a vacuum of -0.09MPa - PVDF composite electrolyte precursor, after being impregnated for 2 hours, is cured by a low-temperature hot-pressing process at 80℃ / 1h and 0.5MPa pressure to form a solid electrolyte;

[0022] S4 Insulation Packaging: The multi-layer series cell body is packaged using an edge-encapsulated insulation process to obtain the finished energy storage device.

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

[0024] 1. World's first high-voltage series sulfide solid-state energy storage: For the first time, sulfide solid-state technology is combined with an internal multi-layer high-voltage series structure to directly achieve high voltage output of over 1000V;

[0025] 2. Completely solves two major pain points of pure sulfides: the air stability of the composite electrolyte is improved by more than 100 times, the brittleness problem is completely solved, and the mass production yield is increased from less than 20% to more than 90%;

[0026] 3. World-leading ultra-low temperature performance: Capacity retention ≥80% at -40℃, and can operate normally in a wide temperature range of -50℃ to 60℃;

[0027] 4. 100% process compatibility: It adopts conventional coating and stacking processes, which are fully compatible with existing supercapacitor and lithium battery production lines, without the need for any additional equipment;

[0028] 5. Extremely high safety: There is no free-flowing liquid electrolyte, no risk of thermal runaway, and it will not catch fire or explode even if punctured or short-circuited. 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 sulfide composite electrolyte high-voltage energy storage device of the present invention.

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

[0033] 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 - 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 sulfide composite electrolyte high-voltage energy storage device described in this embodiment adopts a 56-layer internal series structure and has a rated operating voltage of 1000V.

[0037] The preparation method is as follows:

[0038] 1. Electrode fabrication: A 20μm thick copper-aluminum composite foil current collector is used, with an 80nm thick carbon nanotube anchoring layer coated on both sides; a 100μm thick petroleum coke-based hard carbon negative electrode is coated on the copper layer side, and a 120μm thick natural graphite positive electrode is coated on the aluminum layer side; a 2mm wide insulating edge area is 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 56-layer internal series cell body;

[0040] 3. Composite electrolyte curing: Injection under a vacuum of -0.09MPa -PVDF composite electrolyte precursor, after being impregnated for 2 hours, is cured by low-temperature hot pressing at 80℃ / 1h and 0.5MPa pressure;

[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 72Wh / kg, a power density of 1.8kW / kg, a capacity retention rate of 87.1% after 80,000 cycles, a capacity retention rate of 82.3% at -40℃, and a gas production rate that is 90% lower than that of liquid energy storage at 3.6V high voltage. It also exhibits no electrolyte cracking or internal short circuits.

[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 high-voltage energy storage device with a sulfide composite electrolyte, characterized in that... It includes a multilayer series-connected cell body, dual-sided heterodyne composite electrodes, a sulfide-polymer composite electrolyte, 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 a graphite positive electrode, thus forming a single-foil dual-unit series structure. The multilayer series battery cell body is formed by alternating stacking of the dual-sided heteropolar composite electrodes and the separator, with 50 to 120 layers; The sulfide-polymer composite electrolyte fills the pores of the electrodes and the diaphragm; 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 sulfide-polymer composite electrolyte is Powder-modified PVDF composite electrolyte, single-cell withstand voltage ≥18V.

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 no external module series or parallel connection is required.

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 contains no 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 ≥80,000 cycles and a capacity retention rate of ≥85%.

9. A method for preparing a high-voltage energy storage device with a sulfide composite electrolyte as described in any one of claims 1-8, characterized in that... This includes the following steps: S1 Electrode Fabrication: The electrode was fabricated using a dual-sided heterogeneous composite electrode fabrication 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 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 Composite Electrolyte Curing: A sulfide-polymer composite electrolyte precursor is injected using a vacuum impregnation + low-temperature hot pressing process, and solid electrolyte is formed after curing; 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 S3, the vacuum degree of vacuum impregnation is -0.08 to -0.1 MPa, the low-temperature hot pressing temperature is 60 to 100℃, and the pressure is 0.3 to 1 MPa.

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