Preparation method and application of lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine
By using 2-hydroxy-6-trifluoromethylpyridine to regulate polysulfide behavior and promote SEI formation in lithium-sulfur batteries, the polysulfide shuttle effect and interfacial side reactions in lithium-sulfur batteries were solved, thereby improving the coulombic efficiency and cycle performance of the batteries.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- UNIV OF ELECTRONICS SCI & TECH OF CHINA
- Filing Date
- 2026-02-25
- Publication Date
- 2026-05-12
AI Technical Summary
In practical applications, lithium-sulfur batteries face problems such as polysulfide shuttle effect, loss of active material, severe interfacial side reactions and insufficient rate performance, which lead to reduced coulombic efficiency, rapid capacity decay and significant self-discharge.
2-hydroxy-6-trifluoromethylpyridine is used as an additive in lithium-sulfur battery electrolyte. Through the action of its hydroxyl and trifluoromethyl groups, it regulates the behavior of polysulfides on the positive electrode side and promotes the formation of SEI on the negative electrode side, thereby achieving the localization of polysulfides and improving interface stability.
It effectively suppresses the polysulfide shuttle effect, improves interface stability and battery coulombic efficiency, reduces capacity decay, and improves battery cycle performance and kinetic performance.
Smart Images
Figure CN122025840A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of chemical energy storage batteries, and particularly relates to a preparation method and application of a lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine. Background Art
[0002] Driven by the "dual carbon" background and the demand for renewable energy grid connection, high specific energy secondary batteries have become an important support for energy storage and transportation electrification. Lithium-sulfur batteries have attracted much attention due to advantages such as rich sulfur resources, high theoretical specific capacity, and high theoretical energy density. However, lithium-sulfur batteries still face comprehensive problems in practical applications, such as polysulfide shuttle effect, loss of active substances, serious interfacial side reactions, and insufficient rate performance.
[0003] Specifically, in common ether-based electrolytes (such as DOL (1,3-dioxolane) / DME (1,2-dimethoxyethane) system), long-chain lithium polysulfides (Li2S x , 4 < x ≤ 8) generated during the discharge process have a certain solubility. They can diffuse in the electrolyte, migrate across the separator to the surface of the lithium negative electrode under the drive of the electric field, be reduced and deposited, and trigger continuous side reactions for consumption; during the charging process, they may be re-oxidized and return to the positive electrode side, forming a typical "shuttle cycle". The above charge-discharge process leads to a decrease in Coulomb efficiency, rapid capacity decay, and significant self-discharge.
[0004] In addition, the interfacial chemistry on the lithium negative electrode side in the lithium-sulfur system is particularly complex, specifically manifested in the coupling reaction of solvents, lithium salt anions, polysulfides, and nitrates near the interface. If the formed SEI (solid electrolyte interface film) / deposition layer is not dense or unstable, it will lead to uneven local current density, and then induce uneven lithium deposition and increased polarization. To solve the above problems, existing technologies usually adopt strategies such as positive limit domain, multifunctional separator, catalytic / adsorption materials, and electrolyte engineering (high concentration / local high concentration and functional additives, etc.).
[0005] Among them, the functional additive strategy has high practical value because it has little modification to the existing system, simple process, and can quickly improve performance. However, common additives have problems such as narrow effective window, insufficient compatibility, and side effects on ion transport and interfacial reactions. Therefore, it is still necessary to develop new molecular structures and new action modes to achieve "selective regulation" of polysulfide behavior and interfacial reactions. Summary of the Invention
[0006] To address the problems of strong lithium polysulfide shuttle effect, severe lithium anode side reactions, low coulombic efficiency, short cycle life, and significant self-discharge in the existing technologies, this invention provides a method for preparing lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine and its application, so as to simultaneously achieve the regulation of polysulfide solvation / migration and the improvement of electrode interface stability.
[0007] The technical solution adopted in this invention is as follows:
[0008] A method for preparing a lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine includes the following steps:
[0009] Step 1: Prepare the basic electrolyte for ether-based lithium-sulfur batteries;
[0010] Step 2: Add 2-hydroxy-6-trifluoromethylpyridine to the basic electrolyte of ether-based lithium-sulfur batteries, and after sealing and stirring, obtain a lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine.
[0011] Further, the specific process of step 1 is as follows: dissolve lithium salt and LiNO3 in a DOL / DME mixed solution with a volume ratio of 1:9 to 9:1 to obtain the lithium salt concentration of 0.2 to 3 mol / L and the LiNO3 concentration of 0.1 to 10 wt% in the basic electrolyte of ether-based lithium-sulfur batteries.
[0012] Preferably, the volume ratio of DOL to DME is 1:1; the concentration of lithium salt is 1 mol / L; and the concentration of LiNO3 is 2 wt%.
[0013] The “wt%” refers to the mass fraction, which is the percentage of the mass of a certain component relative to the total mass of its components and other components of the electrolyte (e.g., additive mass / (additive mass + base electrolyte mass) × 100%).
[0014] Furthermore, the lithium salt is LiTFSI (lithium bis(trifluoromethanesulfonyl)imide) or LiFSI (lithium bis(fluorosulfonyl)imide).
[0015] Furthermore, the concentration of 2-hydroxy-6-trifluoromethylpyridine in the lithium-sulfur battery electrolyte obtained in step 2 is 0.1~10wt%.
[0016] Preferably, the concentration of 2-hydroxy-6-trifluoromethylpyridine is 1~5 wt%.
[0017] Furthermore, in step 2, a small amount of ether-based lithium-sulfur battery basic electrolyte is first used to prewet 2-hydroxy-6-trifluoromethylpyridine, and then the prewetted 2-hydroxy-6-trifluoromethylpyridine is added to the remaining ether-based lithium-sulfur battery basic electrolyte to reduce 2-hydroxy-6-trifluoromethylpyridine agglomeration and accelerate dissolution.
[0018] Furthermore, both steps 1 and 2 are performed in the glove box.
[0019] Furthermore, the stirring time in step 2 is 30 min to 48 h.
[0020] Preferably, the stirring time is 24 h to 48 h.
[0021] Furthermore, step 2 also includes a filtration process after stirring to remove trace amounts of insoluble matter.
[0022] The present invention also proposes a lithium-sulfur battery using the above-mentioned lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine.
[0023] Furthermore, the amount of the lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine is: 15~50 μL added to both sides of the separator, with a total amount of 30~100 μL.
[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0025] 1. This invention proposes a method for preparing a lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine and its application. Utilizing the hydroxyl (-OH) and trifluoromethyl (-CF3) groups contained in 2-hydroxy-6-trifluoromethylpyridine as additives in lithium-sulfur battery electrolytes, it can simultaneously regulate the polysulfide behavior on the positive electrode side and the SEI composition on the negative electrode side, achieving the dual goals of "limiting shuttle" and "stabilizing the negative electrode." Furthermore, the preparation method of this invention is simple, reproducible, and easy to implement. It does not require the introduction of complex polymer materials, expensive nanomaterials, or multi-step post-processing. A stable and homogeneous electrolyte can be obtained simply by weighing and stirring in a glove box according to the proportions. It has low equipment requirements, low cost, and is suitable for laboratory screening and industrial scale-up.
[0026] 2. -OH has a restrictive effect on polysulfides. Specifically, -OH can form hydrogen bonds and dipole interactions with lithium polysulfide / solvated ion pairs, and together with pyridine nitrogen sites, it provides multi-site binding, making polysulfides more prone to localization and short-range migration, thereby reducing transmembrane diffusion flux and shuttle effect.
[0027] 3. -CF3 promotes the formation of fluorine-containing SEI (such as LiF). Specifically, -CF3 has a strong electron-withdrawing effect, which can affect the interfacial reaction pathway under electrochemical conditions. Fluorine-containing species at the interface are more likely to contribute stable inorganic components such as LiF. The high mechanical modulus and low electronic conductivity of LiF are conducive to the formation of a denser and more stable SEI, thereby suppressing lithium anode side reactions and uneven deposition.
[0028] 4. On the one hand, the binding of polysulfides by -OH can reduce their flux to the negative electrode, thereby reducing the participation of polysulfides in SEI destruction from the source; on the other hand, the LiF enrichment of SEI promoted by -CF3 can further resist the corrosion of residual polysulfides and solvents. Therefore, -OH and -CF3 form a synergistic closed-loop effect of "suppressing shuttle on the positive electrode side + strengthening SEI on the negative electrode side", which further improves the interface stability and battery coulombic efficiency and reduces capacity decay. Attached Figure Description
[0029] Figure 1 Comparison of Li2S4 adsorption / decolorization experiments between the lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine obtained in Example 1 and the basic electrolyte of an ether-based lithium-sulfur battery.
[0030] Figure 2 Comparison of UV-Vis absorption spectra of the lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine obtained in Example 1 and the basic electrolyte of ether-based lithium-sulfur batteries after the addition of Li2S4.
[0031] Figure 3 This is a comparison chart of the long-cycle performance of full cells assembled based on the lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine obtained in Example 1 and the ether-based lithium-sulfur battery base electrolyte, respectively, at a rate of 0.5C.
[0032] Figure 4 The graph shows a comparison of the rate performance of full cells assembled based on the lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine obtained in Example 1 and the ether-based lithium-sulfur battery base electrolyte, respectively.
[0033] Figure 5 Comparison of EIS (electrochemical impedance spectroscopy) of full cells assembled based on the lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine obtained in Example 1 and the ether-based lithium-sulfur battery basic electrolyte;
[0034] Figure 6 Comparison of F 1s XPS (X-ray photoelectron spectroscopy) spectra of lithium anodes after full-cycle assembly based on the lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine obtained in Example 1 and the basic electrolyte of ether-based lithium-sulfur batteries.
[0035] Figure 7 This is a SEM (scanning electron microscope) image of the surface of the negative electrode lithium sheet of a lithium symmetric battery (Li||Li) assembled based on an ether-based lithium-sulfur battery electrolyte after 50 cycles.
[0036] Figure 8 The image shows the SEM morphology of the negative electrode lithium sheet surface after 50 cycles of a lithium symmetric battery assembled based on the lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine obtained in Example 1.
[0037] Figure 9 The results of EDS (energy dispersive spectroscopy) elemental analysis on the surface of the lithium anode of a lithium symmetric battery assembled based on the basic electrolyte of an ether-based lithium-sulfur battery after cycling.
[0038] Figure 10 The results are EDS elemental analysis of the lithium anode surface after cycling of a lithium symmetric battery assembled based on the lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine obtained in Example 1. Detailed Implementation
[0039] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.
[0040] Example 1
[0041] This embodiment prepares a lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine, including the following steps:
[0042] Step 1: Prepare dry sample vials and stir bar in an inert atmosphere (preferably argon) glove box; DOL and DME can be pre-dried using molecular sieves or equivalent methods; LiTFSI and LiNO3 can be pre-dried under vacuum conditions and then transferred to the glove box for weighing and storage.
[0043] Step 2: Mix DOL and DME at a volume ratio of 1:1, add LiTFSI to make the concentration 1 mol / L, and then add LiNO3 to make the content 2 wt%, to obtain the basic electrolyte of ether-based lithium-sulfur battery, which is marked as "before modification" in the attached figure.
[0044] Step 3: Take 1 mL of ether-based lithium-sulfur battery basic electrolyte and weigh 2-hydroxy-6-trifluoromethylpyridine. First, pre-wet the 2-hydroxy-6-trifluoromethylpyridine with a small amount of ether-based lithium-sulfur battery basic electrolyte. Then, add the pre-wetted 2-hydroxy-6-trifluoromethylpyridine to the remaining ether-based lithium-sulfur battery basic electrolyte to reduce 2-hydroxy-6-trifluoromethylpyridine agglomeration and accelerate dissolution. After sealing, stir magnetically for 24 h to obtain a uniform transparent / nearly transparent lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine with a total mass of 5 wt%. This is marked as "modified" in the attached figure.
[0045] If trace amounts of insoluble matter are present, inert filter membranes (e.g., 0.22~0.45 μm) can be used for filtration; if air bubbles are present, they can be allowed to stand to remove them; then seal and store, avoiding moisture absorption and strong light exposure.
[0046] To verify the advanced nature of the lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine prepared in this embodiment, Li2S4 adsorption / decolorization experiments were conducted on the obtained lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine and the basic electrolyte of ether-based lithium-sulfur batteries. Full cells and lithium symmetric cells were then assembled and tested respectively.
[0047] (a) Li2S4 adsorption / decolorization experiment
[0048] Take 3 mL of ether-based lithium-sulfur battery basic electrolyte and 3 mL of lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine, respectively, and place them in sample vials. Add 50 μL of 0.2 mol / L Li₂S₄ solution to each sample vial and shake well. Observe the color change. The results are as follows: Figure 1 As shown, the basic electrolyte of the ether-based lithium-sulfur battery on the left is brown, while the electrolyte of the lithium-sulfur battery containing 2-hydroxy-6-trifluoromethylpyridine on the right shows a clear fading / clarification trend. This indicates that 2-hydroxy-6-trifluoromethylpyridine has a strong interaction and binding ability with polysulfides, which helps to reduce the migration and shuttle of polysulfides.
[0049] Simultaneously, UV-Vis absorption was compared between the basic electrolyte of ether-based lithium-sulfur batteries and the electrolyte of lithium-sulfur batteries containing 2-hydroxy-6-trifluoromethylpyridine after the addition of Li2S4. The results are as follows: Figure 2 As shown, the UV-Vis absorption comparison results are consistent with... Figure 1 The fading / adsorption phenomena shown are consistent with the fact that the absorption peak of Li2S4 is still present in the basic electrolyte of ether-based lithium-sulfur batteries, while the absorption peak of Li2S4 is significantly reduced in the lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine. This indicates that the lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine has a very significant adsorption effect on Li2S4, further confirming that polysulfides are effectively adsorbed / complexed in the lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine, and the effective dissolution concentration is reduced, thereby reducing the shuttle effect.
[0050] (II) Assembling CR2032 button cells
[0051] The separator is Celgard 2500, the negative electrode is a lithium metal sheet, and the positive electrode is a sulfur positive electrode sheet.
[0052] The preparation process of the sulfur positive electrode is as follows:
[0053] (1) Sulfurization: Weigh 160 mg of sublimed sulfur and 40 mg of Ketjen Black and grind them thoroughly in a mortar until they are evenly mixed; put the mixed powder into a reaction vessel / sealed container and place it in an oven at 155 ℃ for 12 h to carry out melt diffusion sulfurization; after cooling, take it out to obtain the sulfurized complex;
[0054] (2) Slurry preparation: Weigh 140 mg of sulfur-containing compound and mix thoroughly with 40 mg of conductive carbon black (Super P); add 1 mL of PVDF (polyvinylidene fluoride) / NMP (N-methylpyrrolidone) binder solution, wherein the concentration of PVDF is 10 mg / mL, and continue grinding in a mortar until a uniform slurry is formed;
[0055] (3) Coating: The slurry was uniformly coated onto the aluminum foil current collector using a 200 μm scraper. After drying to remove NMP, the positive electrode was punched to obtain the positive electrode sheet. The sulfur loading of the positive electrode sheet was 0.887 mg / cm³. 2 To improve contact and volumetric energy density, rolling can be performed; the electrode sheets should be stored in a dry environment and pre-dried before assembly.
[0056] Assemble the CR2032 button cell batteries inside the glove box, following the bottom-to-top assembly sequence:
[0057] • Negative electrode casing (negative electrode clip);
[0058] •shrapnel;
[0059] • Gasket;
[0060] • Lithium metal sheet;
[0061] • Add 30 μL of electrolyte for the first time;
[0062] •Celgard 2500 diaphragm;
[0063] • Add 30 μL of electrolyte for the second time;
[0064] • Sulfur cathode plate;
[0065] • Positive electrode shell (positive electrode buckle) and encapsulation.
[0066] In this process, the lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine obtained in Example 1 and the ether-based lithium-sulfur battery basic electrolyte were respectively used as electrolytes for addition, resulting in full cells assembled based on the lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine and the ether-based lithium-sulfur battery basic electrolyte respectively; the method of adding electrolyte in two stages helps to ensure sufficient wetting of both sides of the separator and reduce the initial polarization difference; after the battery is packaged, it can be left to stand at room temperature for a certain period of time (e.g., 2~12h) to promote wetting.
[0067] At 25 ℃, the two full cells were charged and discharged using the Blue Battery Testing System, with a voltage window of 1.7 to 2.8 V.
[0068] First, two full cells were subjected to a 0.5C rate long-cycle test, and the specific capacity, coulombic efficiency, and capacity retention were recorded. The test results are as follows: Figure 3 As shown, the lithium-sulfur battery electrolyte based on 2-hydroxy-6-trifluoromethylpyridine exhibits slower capacity decay and more stable coulombic efficiency, reflecting the suppression of polysulfide shuttle and side reactions.
[0069] Secondly, the two full cells were subjected to segmented testing from 0.1C to 2C and then returned to low rate to evaluate kinetics and reversibility. The results are as follows: Figure 4 As shown, the full cell based on the lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine maintains its capacity better at high rates and recovers more fully after returning to low rates, indicating less polarization and better interfacial kinetics.
[0070] Then, EIS was performed on the two full cells, and the results were as follows: Figure 5 As shown, the full cell based on the lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine has a smaller semi-circular diameter and lower interfacial impedance, indicating smoother charge transfer and less polarization. The results are consistent with... Figure 3 and Figure 4 This is corroborated by the other.
[0071] Finally, XPS spectra of the lithium anodes after two full-cell cycles were analyzed. For both full cells, the charge shift was first corrected to 284.8 eV using the C 1s main peak to obtain the charge shift (for the basic electrolyte of ether-based lithium-sulfur batteries: Δ = +0.00 eV; for the electrolyte of lithium-sulfur batteries containing 2-hydroxy-6-trifluoromethylpyridine: Δ = +0.20 eV). Then, the F 1s spectra were compared after the same shift correction. The results are as follows: Figure 6 As shown, after processing with the same baseline and integrating the LiF region (684.0–686.2 eV), it can be seen that the relative area of the LiF region in the full cell based on the lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine is about 2.91 times that of the full cell based on the ether-based lithium-sulfur battery electrolyte. This indicates that the relative proportion of fluorine-containing inorganic components such as LiF at the interface is increased after the introduction of 2-hydroxy-6-trifluoromethylpyridine.
[0072] (III) Assembling CR2032 coin cell lithium symmetric batteries
[0073] The only difference in structure compared to the CR2032 coin cell is that the "sulfur cathode" is replaced with a "lithium metal sheet," while the other components are the same.
[0074] The lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine obtained in Example 1 and the ether-based lithium-sulfur battery basic electrolyte were respectively used as electrolytes for addition to obtain lithium symmetric batteries assembled based on the lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine and the ether-based lithium-sulfur battery basic electrolyte.
[0075] Under 25 ℃ conditions, the two obtained lithium symmetric batteries were subjected to charge-discharge tests using the Blue Battery Testing System. In this embodiment, the lithium symmetric batteries were tested in constant current mode with a current of 2.01 mA. One cycle consisted of 1 hour of constant current discharge followed by 1 hour of constant current charging, and the number of cycles was 50 or more. Taking a lithium sheet with a diameter of 16 mm as an example, its effective area is 2.01 cm². 2 The equivalent current density corresponding to the aforementioned 2.01 mA is 1.0 mA / cm². 2 .
[0076] Figure 7 The image shows the SEM morphology of the negative electrode lithium sheet after 50 cycles of a lithium symmetric battery assembled based on an ether-based lithium-sulfur battery electrolyte. It can be seen that the surface roughening and uneven deposition are obvious, indicating that the interface layer is unstable and the local current density is concentrated, which induces side reactions. Figure 8 This is a SEM image of the surface of the negative lithium electrode of a lithium-sulfur battery assembled based on a lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine after 50 cycles. Figure 7 Its surface is smoother and denser, indicating that the lithium deposition is more uniform and the SEI interface is more stable.
[0077] Figure 9 and Figure 10 The images show the EDS elemental analysis results of the lithium anode surface after cycling of a lithium symmetric battery assembled based on an ether-based lithium-sulfur battery electrolyte and a lithium symmetric battery assembled based on a lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine. It can be seen that... Figure 10 A significant F element signal was detected, and the percentage of relative signal intensity of the fluorine-containing component in the interface layer was increased. This result is consistent with... Figure 6 The enhanced LiF-related peaks in the F 1s spectrum correspond to the phase, further supporting the conclusion that 2-hydroxy-6-trifluoromethylpyridine can promote the enrichment of fluorine-containing inorganic components at the interface.
[0078] Example 2
[0079] This embodiment prepares a lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine. The preparation process is the same as that in Example 1, except that the content of 2-hydroxy-6-trifluoromethylpyridine in step 3 is adjusted to 1 wt% of the total mass of the lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine; the other steps remain unchanged.
[0080] It should be noted that this is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.
Claims
1. A method for preparing a lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine, characterized in that, Includes the following steps: Step 1: Prepare the basic electrolyte for ether-based lithium-sulfur batteries; Step 2: Add 2-hydroxy-6-trifluoromethylpyridine to the basic electrolyte of ether-based lithium-sulfur batteries, and after sealing and stirring, obtain a lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine.
2. The method for preparing the lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine according to claim 1, characterized in that, The concentration of 2-hydroxy-6-trifluoromethylpyridine in the lithium-sulfur battery electrolyte obtained in step 2 is 0.1~10 wt%.
3. The method for preparing the lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine according to claim 1, characterized in that, In step 2, a small amount of ether-based lithium-sulfur battery basic electrolyte is used to prewet 2-hydroxy-6-trifluoromethylpyridine. Then, the prewetted 2-hydroxy-6-trifluoromethylpyridine is added to the remaining ether-based lithium-sulfur battery basic electrolyte to reduce 2-hydroxy-6-trifluoromethylpyridine agglomeration and accelerate dissolution.
4. The method for preparing the lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine according to claim 1, characterized in that, The specific process of step 1 is as follows: dissolve lithium salt and LiNO3 in a DOL / DME mixed solution with a volume ratio of 1:9 to 9:
1. The concentration of lithium salt in the basic electrolyte of ether-based lithium-sulfur battery is 0.2 to 3 mol / L and the concentration of LiNO3 is 0.1 to 10 wt%.
5. A lithium-sulfur battery using a lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine obtained by the preparation method according to any one of claims 1 to 4.
6. The lithium-sulfur battery according to claim 5, characterized in that, The amount of the lithium-sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine is: 15~50 μL added to each side of the separator, with a total amount of 30~100 μL.