An amphiphilic molecule induced bi-domain structure PDOL electrolyte, an in-situ polymerization preparation method thereof and application thereof in lithium-sulfur batteries
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NANTONG UNIV
- Filing Date
- 2026-03-23
- Publication Date
- 2026-08-07
AI Technical Summary
[0005]针对现有技术的不足，本发明提供一种两亲分子诱导双域结构的PDOL电解质及其原位聚合制备方法与在锂硫电池中的应用，为解决现有技术存在的锂硫电池存在的多硫化锂穿梭导致活性物质流失、电池容量快速衰减、倍率性能不足以及穿梭效应引起电池极化和阻抗增加、锂枝晶不受控生长严重缩短电池寿命等核心技术问题
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of lithium-sulfur battery electrolyte preparation technology, specifically relating to a PDOL electrolyte with an amphiphilic induced dual-domain structure, its in-situ polymerization preparation method, and its application in lithium-sulfur batteries. Background Technology
[0002] Lithium-sulfur batteries have a high efficiency of approximately 2600 Wh·kg. -1 With its theoretical energy density and the outstanding advantages of abundant sulfur resources, low cost, and environmental friendliness, lithium-sulfur batteries are widely considered a promising next-generation high-energy-density energy storage system. However, in actual operation, lithium-sulfur batteries still face multiple key technical challenges, especially the shuttle effect caused by the migration of soluble lithium polysulfides in the electrolyte, and the inevitable dendrite growth of the lithium metal anode during repeated deposition / stripping. These problems lead to continuous loss of active materials, decreased battery coulombic efficiency, and significantly shortened cycle life, while also increasing safety hazards such as internal short circuits and thermal runaway.
[0003] Currently, the widely used liquid electrolyte system has significant limitations in lithium-sulfur batteries. On the one hand, it has a strong dissolving ability for lithium polysulfides, promoting the diffusion and shuttle of polysulfides between the positive and negative electrodes, thus exacerbating capacity decay. On the other hand, liquid organic solvents are generally flammable and have poor interfacial stability with the lithium metal anode, easily inducing lithium dendrite growth and membrane puncture, among other safety issues. In contrast, solid electrolytes have inherent advantages in thermal stability and mechanical strength, but their rigidity often leads to insufficient electrode-electrolyte interface contact and high interfacial impedance, resulting in severe polarization and limiting the battery's rate performance and long-term cycle stability.
[0004] Against this backdrop, solid-state electrolytes (SSEs) are considered an effective strategy for improving the safety and cycle stability of lithium-sulfur batteries due to their good structural stability, high safety, and ability to suppress polysulfide shuttle and lithium dendrite growth to a certain extent. However, existing solid-state electrolyte systems generally suffer from low ionic conductivity, poor electrode interface contact, and limited ability to immobilize lithium polysulfides, making it difficult to achieve effective interface control on both the positive and negative electrode sides simultaneously. Therefore, constructing a solid-state electrolyte structure that can be formed through in-situ polymerization and possesses good interface compatibility, and achieving synergistic optimization of polysulfide suppression and lithium dendrite growth control through reasonable interface control strategies, is an important research direction for improving the overall performance of lithium-sulfur batteries. Summary of the Invention
[0005] To address the shortcomings of existing technologies, this invention provides a PDOL electrolyte with an amphiphilic molecule-induced dual-domain structure, its in-situ polymerization preparation method, and its application in lithium-sulfur batteries. This invention aims to solve the core technical problems of existing lithium-sulfur batteries, such as the loss of active material due to lithium polysulfide shuttle, rapid capacity decay, insufficient rate performance, increased battery polarization and impedance caused by the shuttle effect, and uncontrolled growth of lithium dendrites that severely shortens battery life.
[0006] Objective: By introducing lecithin molecules with amphiphilic structural characteristics into the PDOL quasi-solid-state electrolyte system, a symmetrical electrolyte with synergistic regulation of the positive and negative electrode interfaces is constructed, enabling the same electrolyte system to function simultaneously on both the positive and negative electrode sides. On the positive electrode side, the polar groups abundant in lecithin molecules can effectively interact with polysulfides, inhibiting the diffusion and shuttle of soluble polysulfides through the synergistic effect of physical confinement and chemisorption. Simultaneously, it helps regulate the solvation structure of lithium salt, promoting lithium salt dissociation and enhancing lithium-ion migration, thereby improving the overall ionic conductivity and reaction kinetics of the electrolyte. On the negative electrode side, lecithin molecules can preferentially participate in interfacial reactions on the lithium metal surface, inducing the formation of a stable SEI film with uniform composition and dense structure, providing a uniform transport and deposition environment for lithium ions, and effectively inhibiting the nucleation and growth of lithium dendrites. Through the synergistic regulation of the positive and negative electrode interfaces, this electrolyte system achieves simultaneous improvement in polysulfide suppression and lithium negative electrode stability without the need for complex structural design, thus significantly improving the cycle stability and operational safety of lithium-sulfur batteries.
[0007] To achieve the above objectives, this application provides the following technical solution: An in-situ polymerization method for preparing an amphiphilic molecule-induced dual-domain structure PDOL electrolyte specifically includes the following steps: Step 1: In a glove box, mix 40-50 parts of 1,3-dioxapentane, 20-25 parts of ethylene glycol dimethyl ether and 20 parts of lithium bis(trifluoromethanesulfonyl)imide according to the mass ratio and stir for 10-30 min to obtain mixed solution A; Step 2: Add 0.3-0.5 parts of lecithin to mixed solution A and stir for 10-30 minutes to obtain mixed solution B; Step 3: Add 10.5 parts of lithium hexafluorophosphate initiator to mixed solution B, stir for 10-30 min to form a uniform and transparent mixed solution of 1,3-dioxanone / ethylene glycol dimethyl ether / lithium bis(trifluoromethanesulfonylimide) / lecithin, i.e., the precursor solution, denoted as PDOL-LEC.
[0008] Furthermore, the volume ratio of 1,3-dioxapentane to ethylene glycol dimethyl ether is 2:1, the concentrations of lithium bis(trifluoromethanesulfonylimide) and lithium hexafluorophosphate are both 1 mol / L, and the mass of lecithin is 0.5% of the total mass of 1,3-dioxapentane and ethylene glycol dimethyl ether.
[0009] A PDOL electrolyte with an amphiphilic molecularly induced dual-domain structure prepared by any of the above-mentioned in-situ polymerization methods.
[0010] This application also discloses the application of PDOL electrolytes with amphiphilic molecularly induced dual-domain structures prepared by any of the above-mentioned in-situ polymerization methods in lithium-sulfur batteries.
[0011] Furthermore, the specific steps of the application are as follows: S1: Carbon nanotubes and sulfur powder are mixed at a mass ratio of 1:3, manually ground for 30 min, heated at 155~180℃ for 10~14 h under an argon atmosphere, and cooled to room temperature to obtain C / S mixed material; C / S mixed material, Ketjen black and binder PVDF are ground at a weight ratio of 7:2:1 to form a slurry, the slurry is uniformly coated on aluminum foil by a scraping method, and dried at 60℃ for 10~12 h to obtain positive electrode sheet and punched into C / S circular electrode sheet; S2: Assemble the battery in the glove box, using C / S circular electrode as the positive electrode, Celgard 2500 as the separator, and commercial lithium metal sheet as the negative electrode. Place PDOL-LEC on both sides of the separator as the electrolyte and complete the assembly of the lithium-sulfur battery under argon protection. S3: The assembled lithium-sulfur battery is placed in a glove box to allow the electrolyte to polymerize in situ, forming a quasi-solid-state lithium-sulfur battery.
[0012] Furthermore, in S1, the aluminum foil has a thickness of 30 μm, the coating thickness of the scraping method is 120 μm, and the diameter of the C / S circular electrode is 16 mm.
[0013] Furthermore, the PDOL-LEC in S2 is used as the electrolyte between the positive / negative electrode side and the separator.
[0014] Furthermore, the settling time in S3 is 12~24 h, the environment is argon atmosphere, and H2O < 0.1 ppm, O2 < 0.1 ppm.
[0015] This application provides a PDOL electrolyte with an amphiphilic induced dual-domain structure, its in-situ polymerization preparation method, and its application in lithium-sulfur batteries. Compared with the prior art, it has the following advantages: 1. Stable interface, capable of meeting the requirements of positive and negative electrode interfaces separately: By introducing lecithin molecules with amphiphilic structural characteristics into the electrolyte, the same electrolyte system can play a functional role on both the positive and negative electrode sides, thereby specifically meeting the different requirements of the two electrode interfaces; the prepared electrolyte has both good interfacial wettability and certain mechanical strength, which significantly improves the electrolyte / electrode interface contact and compatibility, and is conducive to reducing polarization and improving the overall electrochemical performance of the battery; 2. Effectively suppresses lithium polysulfide shuttle effect and improves ionic conductivity: The PDOL-LEC electrolyte on the positive electrode side can effectively adsorb and fix lithium polysulfides, significantly suppressing their shuttle migration between the positive and negative electrodes, reducing the loss of active materials and interfacial side reactions; among them, the phosphate group in lecithin is conducive to lithium salt dissociation and lithium ion transport, thereby improving the ionic conductivity of the electrolyte and the positive electrode reaction kinetics. 3. Suppressing lithium dendrite growth and constructing a stable SEI to further improve ion conduction performance: The PDOL-LEC electrolyte on the negative electrode side provides a continuous and stable conduction channel for lithium ions, which helps to construct a dense and stable mixed SEI layer in situ on the lithium metal surface, promotes the uniform deposition of lithium ions on the negative electrode surface, effectively alleviates the nucleation and growth of lithium dendrites, further reduces interfacial impedance and improves ion conduction performance and cycle life. 4. Simple process flow, suitable for large-scale preparation: This application adopts in-situ polymerization to directly construct solid electrolyte during battery assembly, without the need for complex equipment and cumbersome steps such as multiple impregnation and coating. The overall process route is simple, the operating conditions are mild, the raw materials are readily available and the cost is low, and it has good prospects for scale-up and industrial application. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of the lithium-sulfur battery prepared in Example 1 of this application; Figure 2 This is a 0.1C-2C rate curve for Example 1 of this application; Figure 3 This is a graph showing the 0.2C cycle performance of Embodiment 1 of this application after 100 cycles. Figure 4 This is a graph showing the 1C cycle performance of Example 1 of this application after 400 cycles. Detailed Implementation
[0017] The present invention will be further described below with reference to the accompanying drawings. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading this disclosure, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.
[0018] 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.
[0019] Example 1: An in-situ polymerization method for preparing an amphiphilic molecule-induced dual-domain structure PDOL electrolyte, specifically including the following steps: Step 1: In a glove box, mix 49 parts of 1,3-dioxapentane, 20 parts of ethylene glycol dimethyl ether and 20 parts of lithium bis(trifluoromethanesulfonyl)imide according to the mass ratio and stir for 30 min to obtain mixed solution A; Step 2: Add 0.5 parts of lecithin to mixed solution A and stir for 10 minutes to obtain mixed solution B; Step 3: Add 10.5 parts of lithium hexafluorophosphate initiator to mixed solution B, stir for 10-30 min to form a uniform and transparent mixed solution of 1,3-dioxanone / ethylene glycol dimethyl ether / lithium bis(trifluoromethanesulfonyl)imide / lecithin, i.e., the precursor solution, denoted as PDOL-LEC. The concentrations of lithium bis(trifluoromethanesulfonyl)imide and lithium hexafluorophosphate are both 1 mol / L.
[0020] The application of the amphiphilic molecularly induced dual-domain structure PDOL electrolyte prepared by the in-situ polymerization method in lithium-sulfur batteries includes the following specific steps: S1: Carbon nanotubes and sulfur powder are mixed at a mass ratio of 1:3, manually ground for 30 min, and then heated at 155~180℃ for 10~14 h under an argon atmosphere. After cooling to room temperature, a C / S mixed material is obtained. The C / S mixed material, Ketjen black and PVDF binder are ground at a weight ratio of 7:2:1 to form a slurry. The slurry is uniformly coated on an aluminum foil with a thickness of 30 μm by a scraping method. The coating thickness of the scraping method is 120 μm. The coating is dried at 60℃ for 10~12 h to obtain a positive electrode sheet, which is then punched into a C / S circular electrode sheet with a diameter of 16 mm. S2: Assemble the battery in the glove box, using C / S circular electrode sheets as the positive electrode, Celgard 2500 as the separator, and commercial lithium metal sheets as the negative electrode. Place PDOL-LEC on both sides of the separator as the electrolyte. PDOL-LEC is used as the electrolyte between the positive / negative electrode side and the separator. Complete the assembly of the lithium-sulfur battery under argon protection. S3: Place the assembled lithium-sulfur battery in a glove box for 12-24 hours in an argon atmosphere with H2O < 0.1 ppm and O2 < 0.1 ppm to allow the electrolyte to polymerize in situ, forming a quasi-solid-state lithium-sulfur battery.
[0021] Comparative Example 1 used PDOL as the electrolyte, which was added dropwise between both the positive and negative electrodes and the membrane: the initial capacity was 717 mAh / g, and the capacity remained at 291.8 mAh / g after 400 cycles (40.7% retention rate). Compared with Example 1, the capacity decreased significantly when only PDOL was added as the electrolyte, indicating that PDOL alone has a limited inhibitory effect on polysulfides.
[0022] Table 1. Cycle performance of lithium-sulfur batteries prepared using different electrolytes in the comparative examples of this invention after 400 cycles. .
[0023] Analysis of Example 1 and Comparative Example 1: Table 1 shows that, compared with the comparative PDOL electrolyte, the PDOL-LEC electrolyte with the introduction of lecithin exhibits significantly improved electrochemical performance. The initial discharge specific capacity of the lithium-sulfur battery corresponding to the PDOL-LEC electrolyte reaches 884 mAh·g. -1 This is significantly higher than the 717 mAh·g of the PDOL system. -1 This indicates that the introduction of lecithin is beneficial to improving the utilization rate of active materials and electrochemical reaction kinetics of the sulfur cathode. Regarding long-cycle performance, the PDOL-LEC battery still maintains 659.8 mAh·g after 400 cycles. -1 The discharge specific capacity of the [specific capacity] was 74.6%, while the capacity of the comparative PDOL battery under the same cycling conditions was only 291.8 mAh·g. -1 The capacity retention rate was 40.7%, exhibiting significant capacity decay. These results demonstrate that the introduction of lecithin can effectively suppress the shuttle effect of lithium polysulfides and improve the stability of the lithium anode interface, thereby significantly reducing the capacity decay rate of the battery during long-term cycling and achieving simultaneous improvement in the cycle stability and operational safety of lithium-sulfur batteries.
[0024] The embodiments selected in the above materials are for ease of understanding and not for limiting the process method. Those skilled in the art can easily modify the process flow or transfer it to other cases without inventive change. If these modifications also fall under the category of similar claims or similar technology of this invention, then the intent of this invention also includes these modifications.
Claims
1. A method for in-situ polymerization preparation of a PDOL electrolyte with an amphiphilic molecule-induced dual-domain structure, characterized in that, Specifically, the steps include the following: Step 1: In a glove box, mix 40-50 parts of 1,3-dioxapentane, 20-25 parts of ethylene glycol dimethyl ether and 20 parts of lithium bis(trifluoromethanesulfonyl)imide according to the mass ratio and stir for 10-30 min to obtain mixed solution A; Step 2: Add 0.3-0.5 parts of lecithin to mixed solution A and stir for 10-30 minutes to obtain mixed solution B; Step 3: Add 10.5 parts of lithium hexafluorophosphate initiator to mixed solution B, stir for 10-30 min to form a uniform and transparent mixed solution of 1,3-dioxanone / ethylene glycol dimethyl ether / lithium bis(trifluoromethanesulfonylimide) / lecithin, i.e., the precursor solution, denoted as PDOL-LEC.
2. The in-situ polymerization preparation method of the PDOL electrolyte with an amphiphilic induced dual-domain structure according to claim 1, characterized in that, The volume ratio of 1,3-dioxapentane to ethylene glycol dimethyl ether is 2:1, the concentrations of lithium bis(trifluoromethanesulfonylimide) and lithium hexafluorophosphate are both 1 mol / L, and the mass of lecithin is 0.5% of the total mass of 1,3-dioxapentane and ethylene glycol dimethyl ether.
3. A PDOL electrolyte with an amphiphilic molecularly induced dual-domain structure prepared by the in-situ polymerization method according to claim 1 or 2.
4. The application of a PDOL electrolyte with an amphiphilic molecularly induced dual-domain structure prepared by the in-situ polymerization method according to claim 1 or 2 in lithium-sulfur batteries.
5. The application according to claim 4, characterized in that, The specific steps are as follows: S1: Carbon nanotubes and sulfur powder are mixed at a mass ratio of 1:3, manually ground for 30 min, heated at 155~180℃ for 10~14 h under an argon atmosphere, and cooled to room temperature to obtain C / S mixed material; C / S mixed material, Ketjen black and binder PVDF are ground at a weight ratio of 7:2:1 to form a slurry, the slurry is uniformly coated on aluminum foil by a scraping method, and dried at 60℃ for 10~12 h to obtain positive electrode sheet and punched into C / S circular electrode sheet; S2: Assemble the battery in the glove box, using C / S circular electrode as the positive electrode, Celgard 2500 as the separator, and commercial lithium metal sheet as the negative electrode. Place PDOL-LEC on both sides of the separator as the electrolyte and complete the assembly of the lithium-sulfur battery under argon protection. S3: The assembled lithium-sulfur battery is placed in a glove box to allow the electrolyte to polymerize in situ, forming a quasi-solid-state lithium-sulfur battery.
6. The application according to claim 5, characterized in that: The aluminum foil in S1 has a thickness of 30 μm, the coating thickness of the scraping method is 120 μm, and the diameter of the C / S circular electrode is 16 mm.
7. The application according to claim 5, characterized in that: The PDOL-LEC in S2 is used as the electrolyte between the positive / negative electrode side and the separator.
8. The application according to claim 5, characterized in that: The settling time in S3 is 12~24 h, the environment is argon atmosphere, and H2O < 0.1 ppm, O2 < 0.1 ppm.