Use of a benzotriimidazole compound in a lithium metal battery
By using benzotriimidazole compounds as electrolyte additives in lithium metal batteries, a LiF component with high ionic conductivity and a stable interface film are generated, solving the problem of lithium dendrite growth and improving the cycle stability and lifespan of the battery.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- XUZHOU NORMAL UNIVERSITY
- Filing Date
- 2026-02-26
- Publication Date
- 2026-05-29
AI Technical Summary
Existing electrolyte systems cannot effectively suppress lithium dendrite growth in lithium metal batteries, leading to instability at the electrode-electrolyte interface and affecting battery cycle life.
By using benzotriimidazole compounds as electrolyte additives, a high ionic conductivity LiF component and a stable interface film are generated through the synergistic effect of fluorine substituents and nitrogen-containing functional groups, thereby inhibiting lithium dendrite growth.
It significantly improves the cycle stability and lifespan of the battery, forms a dense SEI film, and inhibits the formation and growth of lithium dendrites.
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Figure CN122118087A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of lithium metal battery technology, specifically relating to the application of a benzotriimidazole compound in lithium metal batteries. Background Technology
[0002] Lithium metal batteries boast an ultra-high theoretical specific capacity (3860 mAh g). -1 Low redox potential and high energy density have become the core development directions for next-generation high-energy-density energy storage devices. However, when traditional electrolyte systems are applied to lithium metal batteries, key technical problems are exposed: uncontrollable growth of lithium dendrites easily occurs on the surface of lithium metal anodes, which directly leads to a significant decrease in the stability of the electrode-electrolyte interface, resulting in a rapid decline in battery cycle life and seriously restricting the practical application and industrialization of lithium metal batteries.
[0003] The stability of the electrode-electrolyte interface is crucial for the practical application of lithium metal batteries, and suppressing lithium dendrite growth at the lithium metal anode is a core requirement. While existing fluorinated electrolyte additives can improve the interface state to some extent by generating LiF components at the electrode interface, their function is limited, and their effect on suppressing lithium metal anode dendrite growth is limited, failing to meet the requirements for long-term stable operation of lithium metal batteries. Although organic ester additives have good compatibility with the electrolyte system, they struggle to form a stable interfacial protective layer on the electrode surface, thus failing to effectively suppress lithium dendrite growth and exhibiting poor interface regulation. Therefore, addressing the technical shortcomings of existing additives in effectively solving the problems of lithium dendrite growth at the lithium metal anode and the difficulty in stabilizing the electrode-electrolyte interface, developing novel electrolyte additives with excellent interface regulation capabilities has become an urgent technical problem to be solved in this field. Summary of the Invention
[0004] To address the problems mentioned in the background section, the present invention aims to provide an application of benzotriimidazole compounds in lithium metal batteries. The benzotriimidazole compounds used in this invention simultaneously introduce fluorine substituents and nitrogen-containing functional groups into their molecular structure. Through the synergistic effect of these functional groups, efficient suppression of lithium dendrite growth is achieved, stabilizing the electrode interface and improving battery cycle stability.
[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: On the one hand, the present invention provides an application of benzotriimidazole compounds in lithium metal batteries, wherein the structure of the benzotriimidazole compounds is shown in Formula I:
[0006] Formula I,
[0007] Where R is selected from , , , , , , One of them.
[0008] The molecular structure of benzotriimidazole compounds contains polyfluoroalkyl groups, which can, on the one hand, generate highly ionicly conductive LiF components in situ at the electrode interface, enhancing the mechanical strength and density of the interfacial film. On the other hand, relying on the synergistic effect of the benzotriimidazole parent structure and polyfluoroalkyl groups, the growth of lithium dendrites on the surface of lithium metal anode can be effectively inhibited, ensuring the long-term stability of the electrode-electrolyte interface.
[0009] Furthermore, the preparation method of the benzotriimidazole compound includes the following steps:
[0010] (1) Add cyclohexanehexanone octahydrate to water, heat and stir until completely dissolved to obtain an aqueous solution of cyclohexanehexanone octahydrate;
[0011] (2) The octahydrate cyclohexanehexanone aqueous solution was added to ammonia water and stirred at room temperature to obtain a black solution; the black solution was evaporated to dryness and then poured into ethanol to obtain a black suspension; the black suspension was filtered and dried to obtain cyclohexaneheximine.
[0012] (3) Dissolve the cyclohexaneheximine in ethanol, and then add trifluoroacetaldehyde, pentafluorobenzaldehyde, 2,4,6-trifluorobenzaldehyde, 2,6-difluorobenzaldehyde, 2,3,5,6-tetrafluoropyridine-4-carboxaldehyde, 2,2-difluoro-cyclopropane-carboxaldehyde or pentafluoromonopropanaldehyde to react. Pour the mixture after reaction into water, stir, and a solid precipitates out. After filtration and drying, the compound shown in Formula I is obtained.
[0013] Furthermore, the ratio of the octahydrate cyclohexanehexanone to ammonia is (4-6) g: (6-10) mL;
[0014] And / or, the molar ratio of the cyclohexaneheximine and trifluoroacetaldehyde, pentafluorobenzaldehyde, 2,4,6-trifluorobenzaldehyde, 2,6-difluorobenzaldehyde, 2,3,5,6-tetrafluoropyridine-4-carboxaldehyde, 2,2-difluoro-cyclopropane-carboxaldehyde or pentafluoromonohydrate propionaldehyde is 1:3.
[0015] And / or, the drying temperature is 50-60°C;
[0016] And / or, the stirring reaction time in step (1) is 4-6 hours;
[0017] And / or, the temperature of the reaction in step (3) is 70-80°C and the reaction time is 4-6h.
[0018] On the other hand, the present invention provides an electrolyte for lithium metal batteries, comprising the benzotriimidazole compounds described above.
[0019] Furthermore, it also includes organic solvents and lithium salts.
[0020] Further, the organic solvent includes at least one selected from ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, dipropyl carbonate, fluoroethylene carbonate, fluoropropylene carbonate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate, ethyl butyrate, 1,2-dimethoxyethylene, 1,3-dimethoxypropane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, and dimethoxymethane.
[0021] Furthermore, the organic solvent is a combination of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate.
[0022] Furthermore, the volume ratio of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate is (1-3):(1-3):(1-3).
[0023] Furthermore, the lithium salt includes at least one of LiPF6, LiBF4, LiAsF6, LiClO4, LiCF3SO3, LiCH3SO3, LiN(CF3SO2)2, LiN(SO2F)2, and LiBOB.
[0024] Furthermore, the lithium salt concentration is 0.1-2 mol / L.
[0025] Furthermore, the concentration of the benzotriimidazole compound is 0.0001-0.2 mol / L.
[0026] On the other hand, the present invention provides a lithium metal battery, comprising any of the electrolytes for lithium metal batteries described above.
[0027] Compared with the prior art, the present invention has the following beneficial effects:
[0028] (1) The present invention uses benzotriimidazole compounds to construct a highly fluorinated, highly nitrided and structurally stable interface phase. This interface phase can form a stable and dense SEI film on the surface of the lithium metal anode, effectively suppressing the generation and growth of lithium dendrites on the anode surface, and significantly improving the cycle stability and service life of the battery.
[0029] (2) The benzotriimidazole compounds used in this invention have a simple synthesis process, the raw materials are widely available and easy to obtain, and it is easy to achieve large-scale production, with good prospects for industrial application. Attached Figure Description
[0030] Figure 1In the figure, 'a' is a scanning electron microscope image of the lithium metal battery prepared in Comparative Example 1 of this invention after the lithium sheet is immersed in the electrolyte for 24 hours. Figure 1 In this paper, b represents a scanning electron microscope (SEM) image of the lithium metal battery prepared in Example 3 of this invention after the lithium sheet has been immersed in the electrolyte for 24 hours. Figure 1 In this paper, c represents a scanning electron microscope image of the lithium metal battery prepared in Example 4 of this invention after the lithium sheet has been soaked in the electrolyte for 24 hours.
[0031] Figure 2 The constant current charge-discharge curves are for the lithium metal symmetric batteries assembled in Examples 3, 4 and Comparative Example 1 of this invention. Detailed Implementation
[0032] To better understand the content of this invention, the following detailed description is provided in conjunction with specific implementation methods. However, the scope of protection of this invention is not limited to the following embodiments.
[0033] Unless otherwise specified, the test reagents used in the following examples are all conventional biochemical reagents; and the experimental methods described are all conventional methods unless otherwise specified.
[0034] Example 1
[0035] Preparation: First, cyclohexanehexane octahydrate was added to water and heated at 100°C with stirring until completely dissolved to obtain an aqueous solution of cyclohexane octahydrate. Then, the aqueous solution of cyclohexane octahydrate was added to ammonia water (the ratio of cyclohexane octahydrate to ammonia water was 5 g: 7 mL), and the mixture was stirred at room temperature for 6 h to obtain a black solution. The black solution was evaporated to dryness at 60°C and then poured into ethanol to obtain a black suspension. After filtration, the suspension was dried in an oven at 105°C to obtain a black solid cyclohexaneheximine. Cyclohexaneheximine was dissolved in ethanol, and then trifluoroacetaldehyde (the molar ratio of cyclohexaneheximine to trifluoroacetaldehyde was 1:3) was added. The mixture was reacted at 80°C for 4 h. The resulting mixture was poured into water and stirred, resulting in the precipitation of a black solid. After filtration, the solid was dried in an oven at 105°C to obtain a black solid. .
[0036] Example 2
[0037] Preparation: First, cyclohexanehexanone octahydrate was added to water and heated and stirred at 100°C until completely dissolved to obtain an aqueous solution of cyclohexanehexanone octahydrate. Then, the aqueous solution of cyclohexanehexanone octahydrate was added to ammonia water (the ratio of cyclohexanehexanone octahydrate to ammonia water was 5 g: 7 mL), and the mixture was stirred at room temperature for 6 h to obtain a black solution. The black solution was evaporated to dryness at 60°C and then poured into ethanol to obtain a black suspension. After filtration, the suspension was dried in an oven at 105°C to obtain a black solid cyclohexaneheximine. Cyclohexaneheximine was dissolved in dimethyl sulfoxide (DMSO), and then pentafluorobenzaldehyde (the molar ratio of cyclohexaneheximine to pentafluorobenzaldehyde was 1:3) was added. The mixture was reacted at 80°C for 4 h. The resulting mixture was poured into water and stirred, resulting in the precipitation of a black solid. After filtration, the solid was dried in an oven at 105°C to obtain a black solid. .
[0038] Example 3
[0039] Electrolytes for lithium metal batteries: including The ingredients are lithium hexafluorophosphate (LiPF6), an organic solvent (a combination of ethylene carbonate, dimethyl carbonate, and methyl ethyl carbonate in a volume ratio of 1:1:1), and a lithium hexafluorophosphate concentration of 1 mol / L. The concentration is 0.001 mol / L.
[0040] Preparation of electrolyte for lithium metal batteries: Lithium hexafluorophosphate is dissolved in an organic solvent, and then added... The electrolyte for lithium metal batteries is obtained by stirring at room temperature until completely dissolved. The preparation process is carried out in an argon-filled glove box to ensure a controlled inert environment.
[0041] Assembly of lithium metal symmetric batteries: In an argon glove box, using 450μm thick lithium foil as positive and negative electrodes and Celgard-2300 as separator, the lithium metal battery electrolyte prepared above was injected to assemble CR-2032 button batteries.
[0042] Example 4
[0043] Electrolytes for lithium metal batteries: including The ingredients are lithium hexafluorophosphate (LiPF6), an organic solvent (a combination of ethylene carbonate, dimethyl carbonate, and methyl ethyl carbonate in a volume ratio of 1:1:1), and a lithium hexafluorophosphate concentration of 1 mol / L. The concentration is 0.005 mol / L.
[0044] Preparation of electrolyte for lithium metal batteries: Lithium hexafluorophosphate is dissolved in an organic solvent, and then added... The electrolyte for lithium metal batteries is obtained by stirring at room temperature until completely dissolved. The preparation process is carried out in an argon-filled glove box to ensure a controlled inert environment.
[0045] Assembly of lithium metal symmetric batteries: In an argon glove box, using 450μm thick lithium foil as positive and negative electrodes and Celgard-2300 as separator, the lithium metal battery electrolyte prepared above was injected to assemble CR-2032 button batteries.
[0046] Comparative Example 1
[0047] Electrolyte for lithium metal batteries: includes lithium hexafluorophosphate (LiPF6), an organic solvent, the organic solvent being a combination of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate, with a volume ratio of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate of 1:1:1; the concentration of lithium hexafluorophosphate is 1 mol / L.
[0048] Preparation of electrolyte for lithium metal batteries: Lithium hexafluorophosphate was added to an organic solvent and stirred at room temperature until completely dissolved to obtain the electrolyte for lithium metal batteries. The preparation process was carried out in an argon-filled glove box to ensure a controllable inert environment.
[0049] Assembly of lithium metal symmetric batteries: In an argon glove box, using 450μm thick lithium foil as positive and negative electrodes and Celgard-2300 as separator, the lithium metal battery electrolyte prepared above was injected to assemble CR-2032 button batteries.
[0050] The lithium sheets were immersed in the lithium metal battery electrolytes prepared in Examples 3, 4, and Comparative Example 1 for 24 hours, respectively, and then the surface of the lithium sheets was scanned by electron microscopy. The results are as follows. Figure 1 As shown. From Figure 1 As can be seen, the lithium sheet prepared in Comparative Example 1, after being soaked in the electrolyte, has a rough and uneven surface with irregular lithium deposits and protrusions, exhibiting a distinct lithium dendrite structure. This indicates that the lithium sheet undergoes a violent side reaction with the electrolyte prepared in Comparative Example 1, resulting in poor interfacial stability. In contrast, the lithium sheets prepared in Examples 3 and 4, after being soaked in the electrolyte, have a smooth, dense, and even surface without obvious cracks, protrusions, or lithium dendrite structures, forming a continuous and uniform interfacial film. This demonstrates that benzotriimidazole compounds can rapidly adsorb and form a film on the lithium sheet surface, effectively suppressing the side reactions between the lithium sheet and the electrolyte, constructing a stable SEI film, and improving the interfacial stability of the lithium anode.
[0051] The lithium metal symmetric batteries assembled in Examples 3, 4, and Comparative Example 1 were tested at a current density of 2 mA cm⁻¹. -2 The lithium metal deposition amount is 1 mAh cm⁻¹ -2 Cyclic performance tests were conducted under the specified conditions, and the results are as follows: Figure 2 As shown. From Figure 2 As can be seen from the data, the lithium metal symmetric batteries assembled in Examples 3 and 4 have a cycle life of 300 hours, which is much longer than that of the lithium metal symmetric battery assembled in Comparative Example 1.
[0052] The above description is only a specific embodiment of the present invention and not all embodiments. Any equivalent modifications made by those skilled in the art to the technical solutions of the present invention by reading the present invention specification are covered by the claims of the present invention.
Claims
1. The application of a benzotriimidazole compound in lithium metal batteries, wherein the structure of the benzotriimidazole compound is shown in Formula I: Formula I, in, R is selected from , , , , , , One of them.
2. The application according to claim 1, characterized in that, The preparation method of the benzotriimidazole compound includes the following steps: (1) Add cyclohexanehexanone octahydrate to water, heat and stir until completely dissolved to obtain an aqueous solution of cyclohexanehexanone octahydrate; (2) The octahydrate cyclohexanehexanone aqueous solution was added to ammonia water and stirred at room temperature to obtain a black solution; the black solution was evaporated to dryness and then poured into ethanol to obtain a black suspension; the black suspension was filtered and dried to obtain cyclohexaneheximine. (3) Dissolve the cyclohexaneheximine in ethanol, and then add trifluoroacetaldehyde, pentafluorobenzaldehyde, 2,4,6-trifluorobenzaldehyde, 2,6-difluorobenzaldehyde, 2,3,5,6-tetrafluoropyridine-4-carboxaldehyde, 2,2-difluoro-cyclopropane-carboxaldehyde or pentafluoromonopropanaldehyde to react. Pour the mixture after reaction into water, stir, and a solid precipitates out. After filtration and drying, the compound shown in Formula I is obtained.
3. The application according to claim 2, characterized in that, The ratio of cyclohexanehexanone octahydrate to ammonia is (4-6) g: (6-10) mL; And / or, the molar ratio of the cyclohexaneheximine and trifluoroacetaldehyde, pentafluorobenzaldehyde, 2,4,6-trifluorobenzaldehyde, 2,6-difluorobenzaldehyde, 2,3,5,6-tetrafluoropyridine-4-carboxaldehyde, 2,2-difluoro-cyclopropane-carboxaldehyde or pentafluoromonohydrate propionaldehyde is 1:
3. And / or, the drying temperature is 50-60°C; And / or, the stirring reaction time in step (1) is 4-6 hours; And / or, the temperature of the reaction in step (3) is 70-80°C and the reaction time is 4-6h.
4. An electrolyte for lithium metal batteries, characterized in that, Includes the benzotriimidazole compounds as described in claim 1.
5. The electrolyte for lithium metal batteries according to claim 4, characterized in that, It also includes organic solvents and lithium salts.
6. The electrolyte for lithium metal batteries according to claim 5, characterized in that, The organic solvent includes at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, dipropyl carbonate, fluoroethylene carbonate, fluoropropylene carbonate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate, ethyl butyrate, 1,2-dimethoxyethylene, 1,3-dimethoxypropane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, and dimethoxymethane.
7. The electrolyte for lithium metal batteries according to claim 6, characterized in that, The organic solvent is a combination of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate; The volume ratio of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate is (1-3):(1-3):(1-3).
8. The electrolyte for lithium metal batteries according to claim 5, characterized in that, The lithium salt includes at least one of LiPF6, LiBF4, LiAsF6, LiClO4, LiCF3SO3, LiCH3SO3, LiN(CF3SO2)2, LiN(SO2F)2, and LiBOB.
9. The electrolyte for lithium metal batteries according to claim 5, characterized in that, The concentration of the lithium salt is 0.1-2 mol / L; And / or, the concentration of the benzotriimidazole compound is 0.0001-0.2 mol / L.
10. A lithium metal battery, characterized in that, Includes the electrolyte for lithium metal batteries as described in any one of claims 4-9.