A solid-state electrolyte suitable for electrochemical lithium-mediated synthesis of ammonia and a preparation method and application thereof
By using a gel-like solid electrolyte prepared from materials such as polyvinylidene fluoride-hexafluoropropylene, polyethylene oxide, lithium salt, and tetraethylene glycol dimethyl ether, the problems of low stability and low Faraday efficiency in electrochemical lithium-mediated ammonia synthesis were solved, and efficient ammonia synthesis was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- UNIV OF SCI & TECH OF CHINA
- Filing Date
- 2026-03-23
- Publication Date
- 2026-06-02
AI Technical Summary
Existing solid electrolyte materials for electrochemical lithium-mediated ammonia synthesis suffer from poor stability and low Faraday efficiency.
Using polyvinylidene fluoride-hexafluoropropylene, polyethylene oxide, lithium salt and tetraethylene glycol dimethyl ether as the main components, and adding inorganic nanoparticles, a gel-like solid electrolyte is prepared by static evaporation, which improves stability and Faraday efficiency.
The prepared solid electrolyte exhibits high stability and high Faraday efficiency, making it suitable for electrochemical lithium-mediated ammonia synthesis. It also possesses excellent electrochemical performance and good ion transport capabilities.
Smart Images
Figure CN122128725A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of electrochemical materials technology, and in particular to a solid electrolyte suitable for electrochemical lithium-mediated ammonia synthesis, its preparation method, and its application. Background Technology
[0002] With the introduction of the requirements for "carbon peaking" and "carbon neutrality", the traditional Haberthermal catalytic ammonia synthesis method needs to be replaced by a cleaner ammonia synthesis method because it emits carbon dioxide that accounts for about 1.8% of global carbon emissions every year.
[0003] Electrochemical lithium-mediated ammonia synthesis is a green technology that converts nitrogen gas into ammonia (NH3) at room temperature and pressure. It utilizes lithium as the reaction medium, through electrolysis, to convert lithium ions (Li+) in the electrolyte into ammonia. + The lithium metal is reduced and deposited on the electrode surface, forming metallic lithium. This deposited metallic lithium is chemically reactive and spontaneously reacts with the introduced nitrogen gas (N2) to form lithium nitride (Li3N). The proton source added to the system reacts with the lithium nitride, converting it into ammonia (NH3), while lithium ions (Li...) are released. + The electrolyte will be released back into the electrolyte, completing the cycle. This technology is considered a potential alternative to Haberthermal catalytic ammonia synthesis due to its advantages, including operating at room temperature, small equipment footprint, high stability, and the ability to utilize clean electricity throughout the ammonia synthesis process.
[0004] The choice of electrolyte is crucial in the electrochemical lithium-mediated ammonia synthesis system. Solid electrolytes have attracted widespread attention from academia and industry due to their high safety, good processability, and potential for developing ultrathin electrochemical working cells.
[0005] Currently available solid electrolyte materials for electrochemical lithium-mediated ammonia synthesis suffer from problems such as the need for lithium metal pre-deposition, extremely poor stability, and very low Faraday efficiency. Developing novel solid electrolytes that can address these issues is an important research direction in the field of electrochemical lithium-mediated ammonia synthesis. Summary of the Invention
[0006] In view of this, the technical problem to be solved by the present invention is to provide a solid electrolyte suitable for electrochemical lithium-mediated ammonia synthesis, its preparation method and application, wherein the prepared solid electrolyte has good stability and high Faraday efficiency.
[0007] This invention provides a solid electrolyte suitable for electrochemical lithium-mediated ammonia synthesis, the solid electrolyte comprising:
[0008] Polyvinylidene fluoride-hexafluoropropylene, polyethylene oxide, lithium salt and tetraethylene glycol dimethyl ether.
[0009] This invention uses polyvinylidene fluoride-hexafluoropropylene and polyethylene oxide as raw materials to prepare a solid electrolyte. The prepared solid electrolyte is gel-like, which can slow down the evaporation rate of the solvent and thus improve the stability of the solid electrolyte.
[0010] Tetraethylene glycol dimethyl ether can further improve the mechanical properties of solid electrolytes, giving them suitable hardness and better interfacial compatibility, making them more suitable for ion exchange.
[0011] The lithium salt can be any suitable lithium salt known to those skilled in the art, preferably including one or more of lithium tetrafluoroborate, lithium perchlorate, lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, and lithium difluorooxalate borate, with lithium tetrafluoroborate being the most preferred.
[0012] The preferred mass ratio of polyvinylidene fluoride-hexafluoropropylene, polyethylene oxide, lithium salt and tetraethylene glycol dimethyl ether is (3~10):1:(3~10):(10~50).
[0013] In some specific implementations, the mass ratio of polyvinylidene fluoride-hexafluoropropylene to polyethylene oxide is preferably (3~10):1. For example, it can be 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, or 10:1, with 7:1 or 10:1 being the most preferred.
[0014] In some specific implementations, the mass ratio of the lithium salt to polyethylene oxide is preferably (3~10):1. For example, it can be 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, or 10:1, with 3:1 or 7:1 being the most preferred.
[0015] The preferred mass ratio of tetraethylene glycol dimethyl ether to polyethylene oxide is (10~50):1, more preferably (10~30):1, and even more preferably (15~25):1. For example, it can be 15:1, 16:1, 17:1, 18:1, 19:1, 20:1, 21:1, 22:1, 23:1, 24:1, 25:1, and most preferably 24:1.
[0016] Preferably, the solid electrolyte further comprises inorganic nanoparticles.
[0017] The inorganic nanoparticles preferably include one or more of the following: nano-silica particles, nano-alumina particles, nano-titanium dioxide particles, and nano-cerium dioxide particles; the most preferred are nano-silica particles.
[0018] The addition of inorganic nanoparticles can further improve the mechanical strength, ion transport capacity, and ability to bind solvent molecules in polymer films.
[0019] The preferred mass ratio of the inorganic nanoparticles to the polyethylene oxide is 1:(1~5), and for example, it can be 1:1, 1:2, 1:3, 1:4, or 1:5.
[0020] Preferably, the solid electrolyte further includes a solvent.
[0021] The solvent is the residual solvent after it has been allowed to evaporate during the preparation process.
[0022] Preferably, the solvent content is 10 wt% to 40 wt%; for example, it can be 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, or 40 wt%, more preferably 25 wt%. The solvent content ensures good transport performance of hydrogen ions and lithium ions. The solvent content mentioned above refers to the mass content of the solvent in the solid electrolyte.
[0023] The solvent is preferably tetrahydrofuran. This invention provides a method for preparing the above-mentioned solid electrolyte suitable for electrochemical lithium-mediated ammonia synthesis, comprising the following steps:
[0024] A solid phase was obtained by mixing polyvinylidene fluoride-hexafluoropropylene, polyethylene oxide, lithium salt, and inorganic nanoparticles.
[0025] The above solid phase was mixed with tetraethylene glycol dimethyl ether and solvent to obtain a solid electrolyte precursor solution;
[0026] The above-mentioned solid electrolyte precursor solution was allowed to stand and evaporate to obtain the solid electrolyte.
[0027] In a preferred embodiment of the present invention, tetraethylene glycol dimethyl ether and solvent are premixed to obtain a liquid phase, which is then mixed with a solid phase.
[0028] In the liquid phase, the volume ratio of tetraethylene glycol dimethyl ether to solvent is preferably 1:(5~50), more preferably 1:(5~30), and even more preferably 1:(10~15). For example, it can be 1:10, 1:12, 1:12.5, 1:13, 1:15, 1:20, or 1:25.
[0029] The preferred mass ratio of polyvinylidene fluoride-hexafluoropropylene, polyethylene oxide, lithium salt, and inorganic nanoparticles is (3~20):1:(3~10):(0.1~5), more preferably (5~10):1:(3~8):(0.2~3), and even more preferably (7~10):1:(5~7):(0.3~0.5). For example, it can be 10:1:7:0.5, 10:1:5:0.5, 10:1:7:0.33, or 7:1:7:0.5.
[0030] The preferred mass-to-volume ratio of the solid phase to the liquid phase is (2~10) g / 100mL. For example, it can be 2 g / 100mL, 3 g / 100mL, 4 g / 100mL, 5 g / 100mL, 6 g / 100mL, 7 g / 100mL, 8 g / 100mL, 9 g / 100mL, or 10 g / 100mL.
[0031] The preferred temperature for static evaporation is 25~55℃, and for example, it can be 25, 30, 35, 40, 45, 50, or 55℃.
[0032] The preferred time for allowing the evaporation to stand is 8 to 24 hours, and for example, it can be 8, 12, 18, or 24 hours.
[0033] The solid electrolyte prepared by this invention is a uniform and transparent gel-like film with high stability and conversion rate, and has great application potential in electrochemical lithium-mediated ammonia synthesis.
[0034] Based on this, the present invention provides the application of the aforementioned solid electrolyte suitable for electrochemical lithium-mediated ammonia synthesis in the electrochemical lithium-mediated ammonia synthesis reaction. Specifically, as a solid electrolyte for electrochemical ammonia synthesis, it has advantages such as requiring no additional processing, being ready to use immediately after loading, having good stability, and high Faraday efficiency.
[0035] Specifically, the present invention provides an electrochemical battery for electrochemical lithium-mediated ammonia synthesis, comprising the above-mentioned solid electrolyte suitable for electrochemical lithium-mediated ammonia synthesis.
[0036] Compared with the prior art, the present invention provides a solid electrolyte suitable for electrochemical lithium-mediated ammonia synthesis, wherein the solid electrolyte comprises: polyvinylidene fluoride-hexafluoropropylene, polyethylene oxide, lithium salt and tetraethylene glycol dimethyl ether.
[0037] This invention utilizes the excellent swelling effect and low glass transition temperature of polyvinylidene fluoride-hexafluoropropylene and polyethylene oxide copolymer films to significantly improve the ionic conductivity of the films. Therefore, this target material possesses excellent electrochemical performance, offering advantages such as good stability and high Faraday efficiency when used for electrochemical lithium-mediated ammonia synthesis. The preparation method is simple, requires low-cost equipment, and is easy to scale up, providing a high-performance solid-state electrolyte material and facilitating efficient, large-scale lithium-mediated ammonia synthesis. Attached Figure Description
[0038] Figure 1 These are photographs of the solid electrolyte prepared in Example 1;
[0039] Figure 2 These are scanning electron microscope images of the solid electrolyte prepared in Example 2;
[0040] Figure 3 This is a cyclic voltammetry curve of the solid electrolyte prepared in Example 3 during activation;
[0041] Figure 4 This is a voltage-time curve of the solid electrolyte prepared in Example 4 during operation;
[0042] Figure 5 This is an ion chromatography result of the solution in the gas absorption cell after the solid electrolyte prepared in Example 5 has been working for 12 hours;
[0043] Figure 6 This is a schematic diagram of the electrochemical working cell in the embodiment;
[0044] Figure 7 These are the mechanical property test curves of the solid electrolytes prepared in Example 1 and Comparative Example 1. Detailed Implementation
[0045] To further illustrate the present invention, a detailed description is provided below with reference to embodiments. However, it should be understood that these descriptions are merely for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims.
[0046] There are no particular restrictions on the source of any raw materials used in this invention; they can be purchased from the market or prepared using conventional methods known to those skilled in the art.
[0047] Example 1
[0048] Polyvinylidene fluoride-hexafluoropropylene, polyethylene oxide, lithium tetrafluoroborate, and nano-silica were mixed uniformly in a mass ratio of 20:2:14:1 to obtain a solid mixture. Tetrahydrofuran and tetraethylene glycol dimethyl ether were mixed uniformly in a volume ratio of 25:2 to obtain a liquid mixture. 6 g of the resulting solid mixture was dissolved in 100 ml of the liquid mixture to obtain a solid electrolyte precursor solution. The precursor solution was allowed to stand at 45°C for 12 hours to evaporate, yielding the target solid electrolyte film.
[0049] The solid electrolyte photograph is as follows Figure 1 As shown. By Figure 1 It can be seen that the solid electrolyte is a uniform and transparent gel-like film.
[0050] The scanning electron microscope image of the solid electrolyte is as follows: Figure 2 As shown. By Figure 2 It can be seen that the surface of the solid electrolyte is basically uniform, and the striped pattern is caused by the striped protrusions produced during the processing of the bottom of the evaporation vessel.
[0051] The cyclic voltammetry scan results for the solid electrolyte are as follows: Figure 3 As shown. By Figure 3 It can be seen that the solid electrolyte has a clear hydrogen evolution peak caused by hydrogen ion transport and a lithium metal deposition / stripping peak caused by lithium ion transport.
[0052] The solid electrolyte is loaded into the electrochemical working cell (e.g.) Figure 6 The potential-time curve obtained from the operation shown is as follows: Figure 4 As shown. By Figure 4 It can be seen that after a period of lithium metal deposition, a clear lithium metal stripping platform appears in the subsequent OCV process of the solid electrolyte.
[0053] After the solid electrolyte has been working for 12 hours, the concentration of ammonium ions in the gas absorption cell is calculated by ion chromatography, and the results are as follows: Figure 5 As shown. By Figure 5 Subsequent calculations show that a total of 3.39 mg of ammonia was produced in this experiment.
[0054] Example 2
[0055] Polyvinylidene fluoride-hexafluoropropylene, polyethylene oxide, lithium tetrafluoroborate, and nano-silica were mixed uniformly in a mass ratio of 20:2:10:1 to obtain a solid mixture. Tetrahydrofuran and tetraethylene glycol dimethyl ether were mixed uniformly in a volume ratio of 25:2 to obtain a liquid mixture. 6 g of the resulting solid mixture was dissolved in 100 ml of the liquid mixture to obtain a solid electrolyte precursor solution. The precursor solution was allowed to stand at 45°C for 12 hours to evaporate, yielding the target solid electrolyte film.
[0056] After the solid electrolyte was placed in a self-made electrochemical working cell and worked for 12 hours, the concentration of ammonium ions in the gas absorption cell was measured by ion chromatography. The calculation showed that a total of 2.60 mg of ammonia was produced in this experiment.
[0057] Example 3
[0058] Polyvinylidene fluoride-hexafluoropropylene, polyethylene oxide, lithium tetrafluoroborate, and nano-silica were mixed uniformly in a mass ratio of 30:3:21:1 to obtain a solid mixture. Tetrahydrofuran and tetraethylene glycol dimethyl ether were mixed uniformly in a volume ratio of 25:2 to obtain a liquid mixture. 6 g of the resulting solid mixture was dissolved in 100 ml of the liquid mixture to obtain a solid electrolyte precursor solution. The precursor solution was allowed to stand at 45°C for 12 hours to evaporate, yielding the target solid electrolyte film.
[0059] After the solid electrolyte was placed in a self-made electrochemical working cell and worked for 12 hours, the concentration of ammonium ions in the gas absorption cell was measured by ion chromatography. The calculation showed that a total of 3.03 mg of ammonia was produced in this experiment.
[0060] Example 4
[0061] Polyvinylidene fluoride-hexafluoropropylene, polyethylene oxide, lithium tetrafluoroborate, and nano-silica were mixed uniformly in a mass ratio of 14:2:14:1 to obtain a solid mixture. Tetrahydrofuran and tetraethylene glycol dimethyl ether were mixed uniformly in a volume ratio of 25:1 to obtain a liquid mixture. 6 g of the resulting solid mixture was dissolved in 100 ml of the liquid mixture to obtain a solid electrolyte precursor solution. The precursor solution was allowed to stand at 45°C for 12 hours to evaporate, yielding the target solid electrolyte film.
[0062] After the solid electrolyte was placed in a self-made electrochemical working cell and worked for 12 hours, the concentration of ammonium ions in the gas absorption cell was measured by ion chromatography. The calculation showed that a total of 3.03 mg of ammonia was produced in this experiment.
[0063] Example 5
[0064] Polyvinylidene fluoride-hexafluoropropylene, polyethylene oxide, lithium tetrafluoroborate, and nano-silica were mixed uniformly in a mass ratio of 14:2:14:1 to obtain a solid mixture. Tetrahydrofuran and tetraethylene glycol dimethyl ether were mixed uniformly in a volume ratio of 25:2 to obtain a liquid mixture. 6 g of the resulting solid mixture was dissolved in 100 ml of the liquid mixture to obtain a solid electrolyte precursor solution. The precursor solution was allowed to stand at 45°C for 12 hours to evaporate, yielding the target solid electrolyte film.
[0065] After the solid electrolyte was placed in a self-made electrochemical working cell and worked for 12 hours, the concentration of ammonium ions in the gas absorption cell was measured by ion chromatography. The calculated concentration of ammonium ions in the gas absorption cell was 2.86 mg of ammonia produced in this experiment.
[0066] Example 6
[0067] Polyvinylidene fluoride-hexafluoropropylene, polyethylene oxide, and lithium tetrafluoroborate were mixed uniformly in a mass ratio of 10:1:7 to obtain a solid mixture. Tetrahydrofuran and tetraethylene glycol dimethyl ether were mixed uniformly in a volume ratio of 25:2 to obtain a liquid mixture. 6 g of the resulting solid mixture was dissolved in 100 ml of the liquid mixture to obtain a solid electrolyte precursor solution. The precursor solution was allowed to stand at 45°C for 12 hours to evaporate, yielding the target solid electrolyte film.
[0068] After the solid electrolyte was placed in a self-made electrochemical working cell and worked for 12 hours, the concentration of ammonium ions in the gas absorption cell was measured by ion chromatography. The calculated concentration of ammonium ions in the gas absorption cell was 2.27 mg ammonia produced in this experiment.
[0069] Comparative Example 1
[0070] Polyvinylidene fluoride-hexafluoropropylene, polyethylene oxide, and lithium tetrafluoroborate were mixed uniformly in a mass ratio of 10:1:7 to obtain a solid mixture. 6 g of the obtained solid mixture was dissolved in 100 ml of tetrahydrofuran to obtain a solid electrolyte precursor solution. The precursor solution was allowed to stand at 45°C for 12 hours to evaporate, yielding the target solid electrolyte film.
[0071] After the solid electrolyte was placed in a self-made electrochemical working cell and worked for 12 hours, the concentration of ammonium ions in the gas absorption cell was measured by ion chromatography. The calculation showed that less than 0.1 mg of ammonia was produced in this experiment.
[0072] The mechanical properties of the solid electrolyte films prepared in Example 1 and Comparative Example 1 were tested, and the results are as follows: Figure 7 As shown, Figure 7 In the diagram, the black curve represents the mechanical property curve of the solid electrolyte film prepared in Comparative Example 1, and the red curve represents the mechanical property curve of the solid electrolyte film prepared in Example 1. Figure 7 It can be seen that the solid electrolyte film prepared in the embodiments of the present invention has better elasticity and better interfacial compatibility.
[0073] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.
Claims
1. A solid electrolyte suitable for electrochemical lithium-mediated ammonia synthesis, characterized in that, The components of the solid electrolyte include: Polyvinylidene fluoride-hexafluoropropylene, polyethylene oxide, lithium salt and tetraethylene glycol dimethyl ether.
2. The solid electrolyte suitable for electrochemical lithium-mediated ammonia synthesis according to claim 1, characterized in that, The lithium salt includes one or more of lithium tetrafluoroborate, lithium perchlorate, lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, and lithium difluorooxalate borate.
3. The solid electrolyte suitable for electrochemical lithium-mediated ammonia synthesis according to claim 1, characterized in that, The mass ratio of polyvinylidene fluoride-hexafluoropropylene, polyethylene oxide, lithium salt and tetraethylene glycol dimethyl ether is (3~10):1:(3~10):(10~50).
4. The solid electrolyte suitable for electrochemical lithium-mediated ammonia synthesis according to any one of claims 1 to 3, characterized in that, The solid electrolyte also includes: inorganic nanoparticles; The inorganic nanoparticles include one or more of the following: nano-silica particles, nano-alumina particles, nano-titanium dioxide particles, and nano-cerium dioxide particles. The inorganic nanoparticles have a particle size of 40~200nm.
5. The solid electrolyte suitable for electrochemical lithium-mediated ammonia synthesis according to claim 4, characterized in that, The mass ratio of the inorganic nanoparticles to the polyethylene oxide is 1:(1~5).
6. The solid electrolyte suitable for electrochemical lithium-mediated ammonia synthesis according to any one of claims 1 to 5, characterized in that, The solid electrolyte also includes a solvent.
7. The solid electrolyte suitable for electrochemical lithium-mediated ammonia synthesis according to claim 6, characterized in that, The solvent content is 10 wt% to 40 wt%; The solvent is selected from tetrahydrofuran.
8. The method for preparing a solid electrolyte suitable for electrochemical lithium-mediated ammonia synthesis according to any one of claims 1 to 7, comprising the following steps: A solid phase was obtained by mixing polyvinylidene fluoride-hexafluoropropylene, polyethylene oxide, lithium salt, and inorganic nanoparticles. The above solid phase was mixed with tetraethylene glycol dimethyl ether and solvent to obtain a solid electrolyte precursor solution; The above-mentioned solid electrolyte precursor solution was allowed to stand and evaporate to obtain the solid electrolyte.
9. The application of the solid electrolyte according to any one of claims 1 to 7 for electrochemical lithium-mediated ammonia synthesis in the electrochemical lithium-mediated ammonia synthesis reaction.
10. An electrochemical battery for electrochemical lithium-mediated ammonia synthesis, comprising the solid electrolyte as described in any one of claims 1 to 7 suitable for electrochemical lithium-mediated ammonia synthesis.