Dianion salt-based magnesium fuel cell electrolyte and preparation method thereof
By synergistically designing bi-anionic composite salts and modified fillers, the problems of low conductivity, poor stability, and poor interfacial compatibility of magnesium fuel cell electrolytes have been solved, achieving efficient and stable electrolyte preparation suitable for portable electronic devices and electric vehicles.
Patent Information
- Application Number
- CN202610019058.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-08
- Publication Date
- 2026-02-06
AI Technical Summary
Existing magnesium fuel cell electrolytes suffer from problems such as low magnesium ion conductivity, poor thermal and chemical stability, and poor compatibility between the electrolyte and magnesium electrode interface. Furthermore, the preparation process is complex and difficult to achieve industrial production.
An electrolyte with high ionic conductivity and excellent stability was prepared by mixing Mg(OTf)2 and Mg(TFSI)2 in a specific ratio, combining them with a deeply dehydrated solvent and modified filler, and using a specific combination and order of additives, followed by pulsed ultrasound and annealing treatment.
It significantly improves magnesium ion conductivity and electrolyte stability, enhances electrode interface compatibility, extends battery cycle life, and simplifies the manufacturing process, making it suitable for industrial production.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of electrolyte technology, specifically to a dual anion-based magnesium fuel cell electrolyte and its preparation method. Background Technology
[0002] Magnesium fuel cells, as a novel type of metal fuel cell, possess numerous advantages such as high energy density, good safety, abundant raw material sources, and low cost, and have broad application prospects in portable electronic devices, electric vehicles, and emergency power supplies. The electrolyte is one of the core components of a magnesium fuel cell, and its performance directly affects the cell's ion conduction efficiency, cycle stability, interface compatibility, and lifespan.
[0003] Currently, existing magnesium fuel cell electrolytes mainly suffer from the following problems: First, the low conductivity of magnesium ions leads to insufficient battery output power; second, the electrolyte has poor thermal and chemical stability, easily decomposing at high temperatures or during long-term use, affecting battery safety and lifespan; third, the interfacial compatibility between the electrolyte and the magnesium electrode is poor, easily forming a passivation film on the electrode surface, hindering the deposition and dissolution of magnesium, and reducing the battery's cycle performance. Furthermore, the preparation processes of some electrolytes are complex, making industrial-scale production difficult.
[0004] Due to their unique ion dissociation characteristics, dual-anion salt systems have potential advantages in improving the ionic conductivity of electrolytes. However, how to rationally combine the types and proportions of dual-anion salts, and screen suitable solvents and additives to synergistically improve the overall performance of the electrolyte, remains a key challenge in the current research and development of magnesium fuel cell electrolytes. Therefore, developing a dual-anion salt-based magnesium fuel cell electrolyte with high ionic conductivity, excellent stability, and interfacial compatibility, along with its simple and controllable preparation method, is of great significance for promoting the industrialization of magnesium fuel cells. Summary of the Invention
[0005] To address the shortcomings of existing technologies, the present invention aims to provide a dual-anionic magnesium-based fuel cell electrolyte and its preparation method, thereby resolving the problems mentioned in the background section.
[0006] The present invention solves the technical problem by adopting the following technical solution: This invention provides a bianionic magnesium fuel cell electrolyte, composed of the following components by mass percentage: 1-5% bianionic composite magnesium salt, 30-60% propylene carbonate (PC), 10-20% tetrahydrofuran (THF), 0.1-1% magnesium fluoride (MgF2) nanoparticles, 0.05-0.8% modified filler, 1-4% 1,3-dioxolane (DOL), 0.2-1.4% diethylene glycol dimethyl ether (G2), and 1-3% trimethyl phosphate (TMP). The dianionic composite magnesium salt is a mixture of magnesium trifluoromethanesulfonate (Mg(OTf)2) and magnesium bis(trifluoromethanesulfonylimide) (Mg(TFSI)2) in a mass ratio of 1:1.6-2.0. Mg(OTf)2 has good ion dissociation ability, while Mg(TFSI)2 can improve the stability of the electrolyte. The dianionic composite magnesium salt formed by mixing the two in a specific ratio can synergistically improve the magnesium ion conductivity and stability of the electrolyte. Furthermore, propylene carbonate (PC) and tetrahydrofuran (THF) are a mixed solvent obtained after dehydration using 4Å molecular sieves for 24-48 hours, with a water content ≤50ppm. The presence of water can lead to electrolyte hydrolysis and reduce its stability. Deep dehydration using molecular sieves can effectively remove water from the solvent, improving the chemical stability and lifespan of the electrolyte. Furthermore, the particle size of MgF2 nanoparticles is 10-100 nm. MgF2 nanoparticles have good ion conduction promoting effects and can enhance the thermal stability of the electrolyte. After treatment with 0.5% silane coupling agent (KH-550), their dispersibility in the electrolyte can be improved, particle agglomeration can be avoided, and the electrolyte performance can be further optimized. The modified filler is selected from montmorillonite or graphene modified with KH-550. The modified filler surface introduces amino active groups, which can form a synergistic effect with other components in the electrolyte. On the one hand, its layered or sheet-like structure can hinder the decomposition path of the electrolyte, improve the oxidation resistance and long-term stability of the electrolyte; on the other hand, it can adsorb trace impurities in the electrolyte, reduce the damage of impurities to the electrode interface, and promote the rapid transport of magnesium ions, further improving the ion conduction efficiency of the electrolyte. The present invention also provides a method for preparing the above-mentioned dual anion salt-based magnesium fuel cell electrolyte, comprising the following steps: Preparation of S1 composite salt: Mix Mg(OTf)2 and Mg(TFSI)2 at a mass ratio of 1:1.6-2.0, and sonicate for 40-60 minutes, including 10-30 minutes of low-frequency sonication and 30-50 minutes of high-frequency sonication. This combination of low-frequency and high-frequency sonication ensures thorough and uniform mixing of the two magnesium salts, laying the foundation for subsequent dissolution and ion dissociation. S2 Solvent Dehydration: PC and THF are mixed at a mass ratio of 5-3:1 and dehydrated through a 4Å molecular sieve until the water content is ≤50ppm to obtain a dehydrating solvent. PC has a high dielectric constant, which is beneficial to the dissolution of salts, while THF can improve the fluidity of the electrolyte. The two are mixed in a specific ratio and deeply dehydrated to ensure the excellent solubility and stability of the electrolyte. S3 Salt Dissolution: Under an argon-protected atmosphere, mix the composite salt prepared in step S1 with the dehydrating solvent obtained in step S2 at a mass ratio of 1:1.4-3.1, and stir for 6-12 hours to completely dissolve the composite salt. Argon protection prevents the electrolyte from contacting oxygen and moisture in the air, thus preventing oxidation and hydrolysis reactions. S4 Additive Mixing: Strictly follow the order of MgF2 nanoparticles → modified filler → DOL → G2 → TMP, adding MgF2 nanoparticles, modified filler, DOL, G2, and TMP pre-treated with 0.5% silane coupling agent (KH-550) in sequence. Disperse using pulsed ultrasonication for 20-50 minutes, with a pulse mode of 5s on / 2s off. After ultrasonic dispersion, anneal the electrolyte at 80-100℃ for 1 hour under argon protection to obtain the target electrolyte. The specific order of additive addition avoids adverse reactions between components. Adding the modified filler after the MgF2 nanoparticles utilizes the dispersibility of the MgF2 nanoparticles to promote uniform distribution of the modified filler, preventing agglomeration. Pulsed ultrasonication ensures uniform dispersion of all additives in the electrolyte, while annealing further improves the thermal stability of the electrolyte and enhances the compatibility between the modified filler and the electrolyte system.
[0007] Compared with the prior art, the present invention has the following beneficial effects: This invention employs a dual-anionic composite magnesium salt composed of Mg(OTf)₂ and Mg(TFSI)₂ in a specific ratio, synergistically enhancing the magnesium ion conductivity and stability of the electrolyte, thus solving the problem of limited performance of single-anionic salt electrolytes. Deep dehydration of the solvent effectively reduces the water content in the electrolyte, preventing hydrolysis and improving its chemical stability and lifespan. The addition of MgF₂ nanoparticles treated with a silane coupling agent not only improves the ion conductivity of the electrolyte but also enhances its thermal stability, while optimizing the interfacial compatibility between the electrolyte and the magnesium electrode, reducing the formation of passivation films. Specific additive combinations and their order of addition, along with pulsed ultrasonication and annealing processes, further optimize the overall performance of the electrolyte, resulting in excellent cycle stability. The preparation method of this invention is simple, with controllable parameters, requiring no complex equipment, and is suitable for large-scale industrial production. Detailed Implementation
[0008] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to specific examples. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0009] Example 1 A bi-anionic magnesium fuel cell electrolyte comprises the following components by mass percentage: 1% bi-anionic composite magnesium salt, 60% PC, 20% THF, 0.1% MgF2 nanoparticles, 0.05% modified montmorillonite, 1% DOL, 0.2% G2, and 1% TMP. Specifically, the mass ratio of Mg(OTf)2 to Mg(TFSI)2 in the bi-anionic composite magnesium salt is 1:1.6; the MgF2 nanoparticles have a particle size of 10 nm; PC and THF are a mixed solvent obtained after dehydration using 4 Å molecular sieves for 24 hours, with a moisture content ≤50 ppm; and the modified montmorillonite is the product obtained in the above preparation example.
[0010] The method for preparing the above electrolyte includes the following steps: S1 Composite Salt Preparation: Mix Mg(OTf)2 and Mg(TFSI)2 at a mass ratio of 1:1.6 and sonicate for 40 minutes, including 10 minutes of low-frequency sonication and 30 minutes of high-frequency sonication. S2 Solvent dehydration: PC and THF are mixed at a mass ratio of 5:1 and dehydrated through a 4Å molecular sieve for 24 hours. The moisture content is measured to be ≤50ppm to obtain the dehydrating solvent. S3 Salt Dissolution: Under an argon protective atmosphere, the composite salt prepared in step S1 and the dehydrating solvent obtained in step S2 are mixed at a mass ratio of 1:1.4 and stirred for 6 hours until the composite salt is completely dissolved. S4 Additive Mixing: Add MgF2 nanoparticles, modified montmorillonite, DOL, G2 and TMP, which have been pretreated with 0.5% silane coupling agent (KH-550), in sequence, and disperse using pulsed ultrasonication for 20 minutes (5s on / 2s off); after ultrasonication, anneal the electrolyte at 80℃ for 1 hour under argon protection to obtain the target electrolyte.
[0011] Example 2 A bi-anionic magnesium fuel cell electrolyte comprises the following components by mass percentage: 3% bi-anionic composite magnesium salt, 45% PC, 15% THF, 0.5% MgF2 nanoparticles, 0.4% modified graphene, 2.5% DOL, 0.8% G2, and 2% TMP. Specifically, the mass ratio of Mg(OTf)2 to Mg(TFSI)2 in the bi-anionic composite magnesium salt is 1:1.8; the MgF2 nanoparticles have a particle size of 50 nm; PC and THF are a mixed solvent obtained after dehydration at 4 Å molecular sieves for 36 hours, with a moisture content ≤50 ppm; and the modified graphene is the product obtained in the above preparation example.
[0012] The method for preparing the above electrolyte includes the following steps: S1 Composite Salt Preparation: Mix Mg(OTf)2 and Mg(TFSI)2 at a mass ratio of 1:1.8 and sonicate for 50 minutes, including 20 minutes of low-frequency sonication and 40 minutes of high-frequency sonication. S2 Solvent dehydration: PC and THF are mixed at a mass ratio of 4:1 and dehydrated through a 4Å molecular sieve for 36 hours. The moisture content is measured to be ≤50ppm to obtain the dehydrating solvent. S3 Salt Dissolution: Under an argon protective atmosphere, the composite salt prepared in step S1 and the dehydrating solvent obtained in step S2 are mixed at a mass ratio of 1:2.2 and stirred for 9 hours until the composite salt is completely dissolved. S4 Additive Mixing: MgF2 nanoparticles, modified graphene, DOL, G2 and TMP, which have been pretreated with 0.5% silane coupling agent (KH-550), are added sequentially and dispersed by pulsed ultrasonication for 35 minutes (5s on / 2s off). After ultrasonication, the electrolyte is annealed at 90°C for 1 hour under argon protection to obtain the target electrolyte.
[0013] Example 3 A bi-anionic magnesium fuel cell electrolyte comprises the following components by mass percentage: 5% bi-anionic composite magnesium salt, 30% PC, 10% THF, 1% MgF2 nanoparticles, 0.8% modified montmorillonite, 4% DOL, 1.4% G2, and 3% TMP. Specifically, the mass ratio of Mg(OTf)2 to Mg(TFSI)2 in the bi-anionic composite magnesium salt is 1:2.0; the MgF2 nanoparticles have a particle size of 100 nm; PC and THF are a mixed solvent obtained after dehydration using 4 Å molecular sieves for 48 hours, with a moisture content ≤50 ppm; and the modified montmorillonite is the product obtained in the above preparation example.
[0014] The method for preparing the above electrolyte includes the following steps: S1 Composite Salt Preparation: Mix Mg(OTf)2 and Mg(TFSI)2 at a mass ratio of 1:2.0 and sonicate for 60 minutes, including 30 minutes of low-frequency sonication and 50 minutes of high-frequency sonication. S2 Solvent dehydration: PC and THF are mixed at a mass ratio of 3:1 and dehydrated through a 4Å molecular sieve for 48 hours. The moisture content is measured to be ≤50ppm to obtain the dehydrating solvent. S3 Salt Dissolution: Under an argon protective atmosphere, the composite salt prepared in step S1 and the dehydrating solvent obtained in step S2 are mixed at a mass ratio of 1:3.1 and stirred for 12 hours until the composite salt is completely dissolved. S4 Additive Mixing: Add MgF2 nanoparticles, modified montmorillonite, DOL, G2 and TMP, which have been pretreated with 0.5% silane coupling agent (KH-550), in sequence, and disperse using pulsed ultrasonication for 50 minutes (5s on / 2s off); after ultrasonication, anneal the electrolyte at 100℃ for 1 hour under argon protection to obtain the target electrolyte.
[0015] Comparative Example 1 A magnesium fuel cell electrolyte comprises the following components by mass percentage: 1% bi-anionic composite magnesium salt, 60.05% PC, 20% THF, 0.1% MgF2 nanoparticles, 1% DOL, 0.2% G2, and 1% TMP. Specifically, the mass ratio of Mg(OTf)2 to Mg(TFSI)2 in the bi-anionic composite magnesium salt is 1:1.6; the MgF2 nanoparticles have a particle size of 10 nm; and the PC and THF are a mixed solvent obtained after dehydration using 4 Å molecular sieves for 24 hours, with a moisture content ≤50 ppm.
[0016] Preparation method: Except for the S4 additive mixing step, which does not include modified montmorillonite, the other steps are completely the same as in Example 1.
[0017] Comparative Example 2 A magnesium fuel cell electrolyte, with the same mass percentage of each component as in Example 2, except that the modified graphene is replaced with unmodified graphene (with the same particle size and amount).
[0018] Preparation method: Except that the modified filler is unmodified graphene, the other steps are completely the same as in Example 2.
[0019] Comparative Example 3 A magnesium fuel cell electrolyte, with each component having the same mass percentage as in Example 3.
[0020] Preparation method: Except for the addition order of the S4 additive mixing step, which is changed to "DOL → modified montmorillonite → MgF2 nanoparticles → G2 → TMP", the other steps are completely the same as in Example 3.
[0021] The electrolytes prepared in Examples 1-3 and Comparative Examples 1-3 were tested under the same conditions, and the results are shown in the table below: Analysis of test results: Compared with Comparative Example 1 (without modified filler), the magnesium ion conductivity of Examples 1-3 increased by 15-39%, high-temperature stability was significantly enhanced, and long-term cycle capacity retention increased by 12-26%, proving that the introduction of modified filler can form a synergistic effect with electrolyte components, effectively improving the overall performance of the electrolyte; compared with Comparative Example 2 (without modified filler), the ion conductivity of Example 2 increased by 29%, and the cycle stability was significantly better than the comparative example, indicating that KH-550 modification treatment can improve the dispersibility of filler and its compatibility with electrolyte; compared with Comparative Example 3 (with changed addition order), the ion conductivity of Example 3 increased by 28%, and the cycle capacity retention increased by 11-16%, proving that the specific additive addition order of the present invention is the key to ensuring electrolyte performance. In summary, the present invention, through the synergistic design of a dual anion composite salt system, modified filler, and specific preparation process, solves the technical pain points of low ion conductivity, poor stability, and short cycle life of existing electrolytes, and has significant inventiveness.
[0022] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.
[0023] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. A dual-anionic magnesium fuel cell electrolyte, characterized in that, Composed of the following components by mass percentage composition: Bi-anionic complex magnesium salt: 1-5%; Modified filler: 0.05-0.8%; Propylene carbonate: 30-60%; Tetrahydrofuran: 10-20%; Magnesium fluoride nanoparticles: 0.1-1%; 1,3-Dioxolane: 1-4%; Diethylene glycol dimethyl ether: 0.2-1.4%; Trimethyl phosphate: 1-3%.
2. The dual-anionic magnesium fuel cell electrolyte according to claim 1, characterized in that, The bis-anionic composite magnesium salt is a mixture of magnesium trifluoromethanesulfonate and magnesium bis(trifluoromethanesulfonyl)imide, with a mass ratio of 1:1.6-2.
0.
3. The dual-anionic magnesium fuel cell electrolyte according to claim 2, characterized in that, The modified filler is montmorillonite or modified graphene modified with γ-aminopropyltriethoxysilane, wherein the interlayer spacing of the modified montmorillonite is 2-5 nm and the sheet thickness of the modified graphene is 0.8-2 nm.
4. The dual-anionic magnesium fuel cell electrolyte according to claim 3, characterized in that, The propylene carbonate and tetrahydrofuran are a mixed solvent obtained by dehydration of 4Å molecular sieve for 24-48 hours, and the water content of the mixed solvent is ≤50ppm.
5. The dual-anionic magnesium fuel cell electrolyte according to claim 4, characterized in that, The magnesium fluoride nanoparticles have a particle size of 10-100 nm.
6. The dual-anionic magnesium fuel cell electrolyte according to claim 5, characterized in that, The modified filler is prepared by adding montmorillonite or graphene to an ethanol solution, ultrasonically dispersing for 30-40 minutes, adding KH-550 at 3-8% of the mass of montmorillonite or graphene, stirring and reacting at 60-80℃ for 2-4 hours, and then filtering and vacuum drying to obtain the modified filler.
7. A method for preparing the dual anion-based magnesium fuel cell electrolyte according to any one of claims 1-6, characterized in that, Includes the following steps: S1 compound salt preparation: Mix magnesium trifluoromethanesulfonate and magnesium bis(trifluoromethanesulfonyl)imide at a mass ratio of 1:1.6-2.0, and sonicate for 40-60 minutes, including 10-30 minutes of low-frequency ultrasound and 30-50 minutes of high-frequency ultrasound. S2 Solvent dehydration: Propylene carbonate and tetrahydrofuran are mixed at a mass ratio of 5-3:1 and dehydrated through a 4Å molecular sieve until the water content is ≤50ppm to obtain a dehydrating solvent; S3 Salt Dissolution: Under an argon protective atmosphere, the composite salt prepared in step S1 and the dehydrating solvent obtained in step S2 are mixed at a mass ratio of 1:1.4-3.1 and stirred for 6-12 hours to completely dissolve the composite salt. S4 Additive Mixing: Add magnesium fluoride nanoparticles, modified filler, 1,3-dioxolane, diethylene glycol dimethyl ether, and trimethyl phosphate in sequence, pre-treated with 0.5% silane coupling agent KH-550. Disperse the electrolyte using pulsed ultrasonication for 20-50 minutes, with a pulse mode of 5s on / 2s off. After ultrasonic dispersion, anneal the electrolyte at 80-100℃ for 1 hour under argon protection to obtain the target electrolyte.