Polyacid modified polymer solid electrolyte material as well as preparation method and application thereof
By introducing polyacid-modified polymer solid electrolyte materials into lithium-sulfur batteries, the conductivity and stability problems of lithium-sulfur batteries are solved, efficient lithium ion transmission and polysulfide conversion are achieved, and the safety and cycle life of the battery are improved.
Patent Information
- Application Number
- CN202510317379.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-18
- Publication Date
- 2025-07-04
AI Technical Summary
Lithium-sulfur batteries have problems such as poor conductivity of sulfur cathode, polysulfide dissolution and shuttle effect, lack of cycle stability and corrosiveness of electrolytes, which limit their development in commercial applications and safety.
Polyacid-modified polymer solid electrolyte materials are used to improve the mechanical and electrochemical properties of PEO-based solid electrolytes by introducing ionic liquids and polyacid materials, promote lithium ion transmission, and catalyze the conversion of polysulfides, reducing the shuttle effect.
It significantly improves the electrochemical performance and safety of lithium-sulfur batteries, optimizes lithium ion transmission, promotes uniform deposition of lithium metal negative electrodes, extends the battery cycle life and reduces the dissolution of polysulfides.
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Figure CN120261691A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of lithium-sulfur battery materials, and relates to a polyacid-modified polymer solid electrolyte material for all-solid-state lithium-sulfur batteries, a preparation method thereof, and an application thereof. Background Art
[0002] With the continuous growth of global energy demand and the increasing pressure of environmental protection, lithium-sulfur batteries have become the focus of research on next-generation high-performance battery technologies due to their excellent theoretical energy density. Compared with traditional lithium-ion batteries, lithium-sulfur batteries have a theoretical energy density of up to about 5200 Wh / kg, which is mainly due to the high specific capacity of the sulfur cathode of 1675 mAh / g. However, in practical applications, lithium-sulfur batteries still face many challenges, such as poor electrical conductivity of the sulfur cathode, dissolution and shuttle effect of polysulfides, lack of cycle stability, and corrosiveness of the electrolyte.
[0003] Lithium-sulfur batteries have shown great potential application value in the field of secondary battery energy storage due to their excellent energy density and theoretical capacity. Unfortunately, some of its inherent defects have delayed its pace in commercial applications. Traditional liquid lithium-sulfur batteries using ether-based electrolytes often suffer from problems such as shuttle effect and lithium dendrite growth, which not only limit the large-scale application of lithium-sulfur batteries but also pose certain safety hazards. Therefore, the development of new and safe solid electrolytes has become the core concept of concern for scientific researchers.
[0004] To break through these bottlenecks, researchers have proposed the new concept of solid-state lithium-sulfur batteries. Using solid electrolytes can not only avoid the flammability and volatility problems of liquid electrolytes but also have a wider electrochemical window and can withstand higher charging voltages. At the same time, good interfacial compatibility is shown between the solid electrolyte and the sulfur cathode, which helps to slow down the dissolution and diffusion of polysulfides and effectively suppress the shuttle effect in lithium-sulfur batteries, thereby significantly improving the cycle performance and stability of the battery. Theoretically, solid-state lithium-sulfur batteries have a longer cycle life, higher energy density, and better safety, which makes them show broad application prospects in fields such as electric vehicles and large-scale energy storage.
[0005] In recent years, the application of polyoxometalates (POMs) in lithium-sulfur batteries has received extensive attention. Polyoxometalates are a class of inorganic compounds with unique oxygen cluster structures and are regarded as potential preferred materials for improving the performance of lithium-sulfur batteries due to their excellent chemical stability, catalytic properties, and versatility. Their advantages are mainly reflected in: having a strong adsorption capacity for polysulfides, being able to effectively inhibit the shuttle effect, reducing sulfur loss, and improving the Coulombic efficiency; having high chemical and thermal stability, being able to maintain stable performance for a long time during battery operation; the structure and function can be flexibly regulated through coordinated metals and oxygen clusters to meet different battery design requirements, such as increasing capacity and optimizing cycle life.
[0006] Polymer solid-state lithium-sulfur batteries combine the dual advantages of solid-state polymer electrolytes and lithium-sulfur batteries and are a budding high-energy-density energy storage technology. Replacing traditional liquid electrolytes with solid-state polymer electrolytes not only significantly improves the safety of the battery but also effectively alleviates the capacity decay problem caused by the polysulfide shuttle effect in the liquid electrolyte system. Solid-state polymer electrolytes simultaneously serve as both lithium-ion conduction media and separators, and common materials include polyethylene oxide (PEO), polyurethane (PU), and ion liquid-modified polymers, etc. Their advantages lie in providing good flexibility and mechanical stability, effectively inhibiting the formation of lithium dendrites, and at the same time blocking the diffusion of polysulfides. The sulfur cathode is usually compounded with conductive carbon materials to improve conductivity, and functional materials such as polyoxometalates or metal oxides are introduced to further reduce the shuttle effect. The lithium metal anode, as a key component of high energy density, reduces the risk of dendrite growth under the protection of the solid electrolyte. Compared with traditional lithium-sulfur batteries, this type of battery has achieved significant improvements in terms of safety and cycle life, and the low density of the polymer makes it lighter, which is very suitable for applications in flexible devices and electric transportation fields.
[0007] However, polymer solid-state lithium-sulfur batteries also face some challenges, such as relatively low ionic conductivity, insufficient interfacial stability, and the dissolution problem of the sulfur cathode, etc., which limit the performance of their practical applications. Therefore, researchers are constantly overcoming technical difficulties by means of optimizing the structural design of polymers, introducing nanocomposites, improving electrode interfaces, and increasing sulfur loading. Looking ahead, with the research and development of new polymer electrolyte materials and the continuous improvement of manufacturing processes, this type of battery is expected to play a crucial role in high-safety and high-energy-density energy storage systems, providing more efficient and reliable energy solutions for portable devices and new energy transportation vehicles. Summary of the Invention
[0008] Technical problem to be solved: The present invention provides a polyacid-modified polymer solid electrolyte material for all-solid-state lithium-sulfur batteries, its preparation method and application. This novel polymer electrolyte material can improve the electrochemical performance of lithium-sulfur batteries and solve the problems existing in the background art. By introducing ionic liquids and polyacid materials, the inventors effectively improved the mechanical properties of PEO-based solid electrolytes, promoted the random movement of PEO flexible segments, improved the lithium-ion transport efficiency, and at the same time enabled it to expose more active sites, providing a redox path for the sulfur cathode and promoting the conversion of polysulfides.
[0009] Technical solution: A preparation method of a polyacid-modified PEO-based solid electrolyte material includes the following steps: mixing polyethylene oxide (PEO), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), ionic liquid, crosslinking agent, initiator and polyacid material, where the mass ratio of polyethylene oxide (PEO), lithium bis(trifluoromethanesulfonyl)imide (LiTSFI) and ionic liquid is (12 - 20):(1 - 3):(6 - 10), the dosage of the crosslinking agent is 1% - 5% of the mass of the above mixing system, the dosage of the initiator is 0.1% - 1% of the mass of the above mixing system, and the dosage of the polyacid material is 1% - 5% of the mass of the above mixing system to obtain a PEO-based polymer precursor solution, then using the casting method to naturally flow, and then drying in vacuum to form a solid electrolyte membrane.
[0010] Preferably, the average molecular weight of the above polyethylene oxide (PEO) is 1 million - 10 million.
[0011] The above ionic liquid is 1-vinyl-3-butylimidazolium bis(trifluoromethanesulfonyl)imide; the crosslinking agent is polyethylene glycol methacrylate; the initiator is azobisisobutyronitrile; the polyacid material is phosphotungstic acid.
[0012] Preferably, the mass ratio of the above ethylene oxide (PEO) to lithium bis(trifluoromethanesulfonyl)imide (LiTSFI) is 8:1.
[0013] Preferably, the volume ratio of the above ionic liquid to the crosslinking agent is 10:1.
[0014] Preferably, the final thickness of the above natural flow is 200 - 300 microns.
[0015] Preferably, the above drying temperature is 80 °C and the time is 48 hours.
[0016] The polyacid-modified PEO-based solid electrolyte material prepared by the above preparation method.
[0017] The application of the above polyacid-modified PEO-based solid electrolyte material in the preparation of lithium-sulfur batteries.
[0018] Beneficial effects: By adding ionic liquid additives, the present invention effectively improves the mechanical and electrochemical properties of the solid electrolyte. By promoting the random movement of polymer segments, the ion transport of the lithium-sulfur battery is optimized. At the same time, the polyacid material gives sufficient support strength to the polymer skeleton, catalyzes the conversion of polysulfides inside the battery, reduces the shuttle effect, and promotes the uniform deposition and stripping of lithium ions on the lithium metal anode. Description of the Drawings
[0019] Figure 1 SEM photograph of the solid electrolyte membrane prepared in the example.
[0020] Figure 2 XRD pattern of the solid electrolyte material prepared in the example.
[0021] Figure 3 Rate performance of the solid electrolyte material prepared in the example in the lithium-sulfur battery. Detailed Description of the Invention
[0022] A polyacid-modified polymer solid electrolyte material for all-solid-state lithium-sulfur batteries and a preparation method thereof according to the present invention are characterized in that the following steps are specifically included:
[0023] Comparative Example 1
[0024] (1) 11.1 g of PEO with an average molecular weight of 1 million to 10 million and 1.38 g of LiTFSI are respectively added to 100 mL of acetonitrile solvent, and stirred in an anhydrous and oxygen-free environment at 60 °C for at least 24 hours, with a stirring speed of 800 revolutions per minute.
[0025] (2) Take the solution in step (1) and let it flow naturally on a flat surface until it is 3 mm thick, and age at room temperature for 24 hours to obtain a semi-finished solid electrolyte membrane.
[0026] (3) Dry the product obtained in (2) in a vacuum environment at 80 °C for 48 hours to obtain a solid electrolyte membrane, and cut it into circular pieces with a diameter of 20 microns to obtain the final product.
[0027] (4) Assemble the prepared solid electrolyte membrane with a sulfur cathode and a lithium metal anode into a CR2032 coin cell for charge and discharge testing.
[0028] Example 1
[0029] (1) Add 11.1 g of PEO with an average molecular weight of 10 - 1,000,000, 1.38 g of LiTFSI, 5 mL of 1-vinyl-3-butylimidazolium bis(trifluoromethanesulfonyl)imide, 0.5 mL of polyethylene glycol methacrylate, 0.75 g of phosphotungstic acid, and 15 mg of azobisisobutyronitrile into 100 mL of acetonitrile solvent, and stir for at least 24 hours in an anhydrous and anaerobic environment at 60 °C with a stirring speed of 800 revolutions per minute.
[0030] (2) Take the solution in step (1) and let it flow naturally on a plane until it is 3 mm thick, and age it at room temperature for 24 hours to obtain a semi-finished solid electrolyte membrane.
[0031] (3) Dry the product obtained in (2) in a vacuum environment at 80 °C for 48 hours to obtain a solid electrolyte membrane, and cut it into circular pieces with a diameter of 20 microns to obtain the final product.
[0032] (4) Assemble the prepared solid electrolyte membrane with a sulfur positive electrode and a lithium metal negative electrode into a CR2032 coin cell for charge and discharge testing.
[0033] Example 2
[0034] (1) Add 11.1 g of PEO with an average molecular weight of 10 - 1,000,000 and 2.76 g of LiTFSI into 100 mL of acetonitrile solvent respectively, and stir for at least 24 hours in an anhydrous and anaerobic environment at 60 °C with a stirring speed of 800 revolutions per minute.
[0035] (2) Take the solution in step (1) and let it flow naturally on a plane until it is 3 mm thick, and age it at room temperature for 24 hours to obtain a semi-finished solid electrolyte membrane.
[0036] (3) Dry the product obtained in (2) in a vacuum environment at 80 °C for 48 hours to obtain a solid electrolyte membrane, and cut it into circular pieces with a diameter of 20 microns to obtain the final product.
[0037] (4) Assemble the prepared solid electrolyte membrane with a sulfur positive electrode and a lithium metal negative electrode into a CR2032 coin cell for charge and discharge testing.
[0038] Example 3
[0039] (1) Add 11.1 g of PEO with an average molecular weight of 10 - 1,000,000 and 5.52 g of LiTFSI into 100 mL of acetonitrile solvent respectively, and stir for at least 24 hours in an anhydrous and anaerobic environment at 60 °C with a stirring speed of 800 revolutions per minute.
[0040] (2) Take the solution in step (1) and let it flow naturally on a plane until it is 3 mm thick, and age it at room temperature for 24 hours to obtain a semi-finished solid electrolyte membrane.
[0041] (3) The product obtained in (2) is dried in a vacuum environment at 80 °C for 48 hours to obtain a solid electrolyte membrane, which is cut into circular pieces with a diameter of 20 microns to obtain the final product.
[0042] (4) The prepared solid electrolyte membrane is assembled with a sulfur positive electrode and a lithium metal negative electrode into a CR2032 coin cell for charge-discharge testing.
[0043] Example 4
[0044] (1) 11.1 g of PEO with an average molecular weight of 1 million to 10 million, 1.38 g of LiTFSI, 5 mL of 1-vinylimidazole, 0.5 mL of polyethylene glycol methacrylate, 0.75 g of phosphotungstic acid, and 15 mg of azobisisobutyronitrile are added to 100 mL of acetonitrile solvent, and stirred in an anhydrous and oxygen-free environment at 60 °C for at least 24 hours, with a stirring speed of 800 revolutions per minute.
[0045] (2) Take the solution in step (1) and let it flow naturally on a flat surface until it is 3 mm thick, and age at room temperature for 24 hours to obtain a semi-finished solid electrolyte membrane.
[0046] (3) The product obtained in (2) is dried in a vacuum environment at 80 °C for 48 hours to obtain a solid electrolyte membrane, which is cut into circular pieces with a diameter of 20 microns to obtain the final product.
[0047] (4) The prepared solid electrolyte membrane is assembled with a sulfur positive electrode and a lithium metal negative electrode into a CR2032 coin cell for charge-discharge testing.
[0048] Regarding the various preferred ratios and ionic conductivities of the PEO-based composite solid electrolytes in the examples and comparative examples provided by the present invention, the inventors also verified them through experiments. For details, please refer to Table 1 below.
[0049] Table 1
[0050]
[0051] The above characterization test data on the mechanical properties of the polymer solid electrolyte membrane in the present invention were obtained through stress-stretching tests. The previously prepared polymer was cut into strips with a specification of 50 mm × 20 mm, and a universal testing machine was used to stretch the samples at a stretching speed of 5 mm / min, and the pressure when the breaking elongation rate reached 100% was recorded. The data are shown in Table 1.
[0052] The above embodiments describe the preferred embodiments of the present invention, and do not limit the present invention. Without departing from the spirit or scope of the present invention, technical improvements and equivalent substitutions made by relevant technicians to the present invention are within the protection scope of the present invention.
Claims
1. A preparation method of a polyoxometalate-modified PEO-based solid electrolyte material, characterized in that It includes the following steps: Mix polyethylene oxide (PEO), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), ionic liquid, crosslinking agent, initiator and polyacid material. The mass ratio of the polyethylene oxide (PEO), lithium bis(trifluoromethanesulfonyl)imide (LiTSFI) and ionic liquid is (12 - 20):(1 - 3):(6 - 10). The dosage of the crosslinking agent is 1% - 5% of the mass of the above mixing system. The dosage of the initiator is 0.1% - 1% of the mass of the above mixing system. The dosage of the polyacid material is 1% - 5% of the mass of the above mixing system to obtain a PEO-based polymer precursor solution, then use the doctor blade method for natural doctor blading, and then vacuum dry to form a solid electrolyte membrane.
2. The preparation method according to claim 1, wherein The average molecular weight of the polyethylene oxide (PEO) is 100,000 - 1,000,000.
3. The preparation method according to claim 1, wherein The ionic liquid is 1-vinyl-3-butylimidazolium bis(trifluoromethanesulfonyl)imide; the crosslinking agent is polyethylene glycol methacrylate; the initiator is azobisisobutyronitrile; the polyacid material is phosphotungstic acid.
4. The preparation method according to claim 1, characterized in that, The mass ratio of the polyethylene oxide (PEO) to lithium bis(trifluoromethanesulfonyl)imide (LiTSFI) is 8:
1.
5. The preparation method according to claim 1, wherein The volume ratio of the ionic liquid to the crosslinking agent is 10:
1.
6. The preparation method according to claim 1, characterized in that, The final thickness of the natural doctor blading is 200 - 300 microns.
7. The preparation method according to claim 1, wherein The drying temperature is 80 °C and the time is 48 hours.
8. A polyacid-modified PEO-based solid electrolyte material prepared by the preparation method according to any one of claims 1 - 7.
9. Use of the polyacid-modified PEO-based solid electrolyte material according to claim 8 in the preparation of a lithium-sulfur battery.