A method for screening of mxene for lithium-sulfur battery host material
By screening suitable MXene materials through DFT calculations and molecular dynamics simulations, the shuttle effect problem of lithium polysulfides in lithium-sulfur batteries was solved, and the material's efficient anchoring and catalytic performance were improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- UNIV OF ELECTRONICS SCI & TECH OF CHINA
- Filing Date
- 2026-04-15
- Publication Date
- 2026-07-10
AI Technical Summary
The shuttle effect of lithium polysulfides in lithium-sulfur batteries leads to loss of active material and capacity decay. Existing technologies are difficult to effectively anchor lithium polysulfides, and traditional screening methods cannot fully evaluate anchoring ability and catalytic activity.
MXene materials with suitable anchoring capabilities were screened using DFT calculations, and their kinetic stability and catalytic performance were verified by molecular dynamics simulations. MXene materials that can suppress the shuttle effect were then screened out.
This has accelerated the research and development of host materials for lithium-sulfur batteries, improved the overall performance of the materials, and ensured their stability and catalytic activity in dynamic electrochemical environments.
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Figure CN122369640A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of lithium-sulfur battery materials technology, and more specifically, to a method for screening MXene for lithium-sulfur battery host materials. Background Technology
[0002] The "shuttle effect" of lithium polysulfides in lithium-sulfur batteries is a core challenge restricting their commercial application. During charge and discharge, the generated lithium polysulfides shuttle between the positive and negative electrodes, leading to loss of active material and capacity decay. The insulating solid-solid transition from Li₂S₂ to Li₂S is the rate-limiting step in the sulfur reduction reaction (SRR) kinetics, and the anchoring ability of the host material to Li₂S₂ directly affects the performance of lithium-sulfur batteries.
[0003] MXene materials, with their high electrical conductivity and rich surface chemistry, are highly promising host materials for lithium-sulfur batteries. The adsorption energy between the substrate and lithium polysulfide molecules can measure the anchoring ability of the host material in lithium-sulfur batteries. Calculating the adsorption energy of MXene-Li2S2 allows for the screening of host materials that effectively suppress the shuttle effect based on the strength of the adsorption energy. Directivity-based pressure calculations (DFT) can quickly obtain the adsorption energy, and screening materials using DFT calculations can guide experimental research and accelerate the material development process. Summary of the Invention
[0004] The purpose of this invention is to screen out MXene materials that can effectively anchor lithium polysulfides as sulfur host materials for lithium-sulfur batteries, thereby suppressing the shuttle effect and catalyzing the conversion of sulfur.
[0005] To achieve the above objectives, the present invention employs the following technical solution:
[0006] This invention provides a method for screening MXenes for lithium-sulfur battery host materials, characterized by comprising the following steps:
[0007] Step S1: Collect MXene structures and model lithium polysulfide molecules using VESTA. Optimize the structure of the target MXene material and lithium polysulfide molecules using first-principles calculation software to obtain stable structures and acquire the corresponding system energies.
[0008] Step S2: Using the MXene structure optimized in Step S1 as a substrate, construct the adsorption structure of lithium polysulfide molecules on different MXenes;
[0009] Step S3: Perform structural optimization calculations on the adsorption structure constructed in step S2 using first-principles calculation software to obtain a reasonable adsorption configuration and acquire the energy of the adsorption system;
[0010] Step S4: Combining the energy obtained in step S1 and the adsorption system energy obtained in step S3, calculate the adsorption energy of different MXenes with lithium polysulfide molecules.
[0011] Step S5: Determine the target adsorption energy range through DFT calculation and analysis, and screen materials according to the target adsorption energy range to obtain preliminary candidate materials;
[0012] Step S6: Verify the dynamic stability of the preliminary candidate material by performing ab initio molecular dynamics simulations using first-principles calculation software;
[0013] Step S7: For kinetically stable candidate materials, use the Gibbs free energy formula ΔG=ΔE+ΔE ZPE -TΔS was used to calculate the free energy of each stage of the sulfur reduction reaction; its catalytic performance was analyzed based on the corresponding free energy step diagram, and finally, the high-performance MXene lithium-sulfur battery host material was selected.
[0014] Where ΔE represents the change in the ground-state energy of the system before and after adsorption, ΔE ZPE ΔS represents the change in zero-point energy, ΔS represents the entropy change, and T represents the temperature, with a value of 298K.
[0015] In the above scheme, the lithium polysulfide molecule is Li2S2.
[0016] In step S5, the upper limit of the adsorption energy intensity is greater than -3.2 eV; the lower limit of the adsorption energy intensity is less than -1 eV; and the target adsorption energy range is from -3.2 eV to -1 eV.
[0017] In the above scheme, the method for determining the target adsorption energy range includes:
[0018] The theoretical upper limit of the adsorption energy without destruction of the lithium polysulfide molecular structure was determined by DFT calculation, and the theoretical lower limit of the adsorption energy was determined by DFT calculation of the adsorption energy of Li2S2 molecules by two commonly used organic electrolytes in lithium-sulfur batteries, dioxolane DOL and dimethyl ether DME. Based on this, a safety buffer value was added to determine the final screening range.
[0019] In the above scheme, in step S6, the ab initio molecular dynamics simulation is performed for at least 10 ps at 300 K.
[0020] In the above scheme, in step S7, the sulfur reduction reaction process includes the following reaction pathway:
[0021] *S8 + 2Li + + 2e - → *Li2S8 (Equation 1)
[0022] 3*Li₂S₈ + 2Li + + 2e - → 4*Li2S6 (Equation 2)
[0023] 2*Li₂S₆ + 2Li + + 2e - → 2*Li2S4 (Equation 3)
[0024] *Li₂S₄ + 2Li + + 2e - → 2*Li2S2 (Equation 4)
[0025] *Li₂S₂ + 2Li + + 2e - → 2*Li2S (Equation 5)
[0026] In the above scheme, in step S1, the collection of MXene crystal structures includes collecting MXene crystal structures with terminal types of -O, -F, -Cl, and -Br.
[0027] In the above scheme, step 4 specifically involves:
[0028] Combining the energy obtained in step S1 and the adsorption system energy obtained in step S3, the adsorption energy is calculated using the formula E. ads = E total - E LiPS - E sub The adsorption energies of different MXenes with Li2S2 were obtained, where E total E represents the energy of the adsorption system. LiPS E is the molecular energy of Li2S2. sub The energy of the MXene base.
[0029] The present invention also provides a lithium-sulfur battery host material, obtained by the MXene screening method for lithium-sulfur battery host materials described above.
[0030] Compared with the prior art, the present invention has the following advantages:
[0031] 1. This invention rapidly obtained the adsorption energy of the MXene-Li2S2 system through DFT calculations, screened out MXene materials with strong anchoring capabilities based on adsorption energy conditions, and further screened out MXene materials that can simultaneously suppress shuttle effect and promote sulfur conversion in lithium-sulfur batteries through AIMD stability verification and SRR analysis, thus accelerating the research and development process of host materials for lithium-sulfur batteries.
[0032] 2. This invention combines adsorption energy screening (steps S4-S5), kinetic stability verification (step S6), and sulfur reduction free energy calculation (step S7) to achieve a synergistic effect, solving the problem that single-index screening cannot comprehensively evaluate the overall performance of lithium-sulfur battery host materials. Traditional screening methods often rely solely on a single static adsorption energy index to assess anchoring ability. This is essentially a property under thermodynamic equilibrium, reflecting the energy tendency of the adsorption process, but it cannot accurately describe the actual service performance of materials in real dynamic, non-equilibrium electrochemical environments. The practical application potential of materials also needs to consider properties such as kinetic stability and catalytic activity. This invention, through a multi-step combined screening logic, first uses the adsorption energy range to identify materials with suitable anchoring strength, then eliminates unstable systems through molecular dynamics simulation, and finally confirms the catalytic ability of candidate materials through sulfur reduction reaction free energy analysis. This combined approach ensures that the finally screened MXene host materials can simultaneously meet the multiple requirements of suppressing the shuttle effect, maintaining structural stability, and promoting sulfur conversion, significantly improving R&D efficiency and accelerating the discovery process of high-performance lithium-sulfur battery host materials. Attached Figure Description
[0033] Figure 1 This is the free energy diagram of the SRR reaction pathway in an example of the present invention;
[0034] Figure 2 This is a structural diagram of the stable host material finally selected from the examples of this invention; Detailed Implementation
[0035] To better understand this invention, the following detailed description, in conjunction with examples, will illustrate the invention. However, it should be noted that this invention is not limited to these embodiments, and any modifications or equivalent substitutions made to this invention should be covered within the scope of the claims.
[0036] This invention provides a method for screening MXenes for lithium-sulfur batteries. A large amount of adsorption energy between MXenes and lithium polysulfide molecules is rapidly obtained through DFT calculations. MXene materials that can effectively anchor lithium polysulfide molecules are screened based on the adsorption energy. The kinetic stability of the candidates is verified through ab initio molecular dynamics simulations. Finally, the free energy of sulfur reduction is calculated for stable candidates to verify the catalytic performance of the screening results. MXenes that can effectively suppress the shuttle effect are successfully screened as host materials for lithium-sulfur batteries.
[0037] The specific steps are as follows:
[0038] S1: Collect MXene structures and model Li2S2 using VESTA. Optimize the structure of the target MXene material and Li2S2 molecules using the first-principles calculation software VASP to obtain stable structures and corresponding system energies.
[0039] S2: Using the MXene structure optimized in step S1 as a substrate, the adsorption structure of Li2S2 molecules on different MXenes is constructed using a Python script.
[0040] S3: Perform structural optimization calculations on the adsorption structure constructed in step S2 using VASP to obtain a reasonable adsorption configuration and acquire the energy of the corresponding adsorption system.
[0041] S4: Combining the energy obtained in step S1 and the adsorption system energy obtained in step S3, calculate E according to the adsorption energy formula. ads = E total - E LiPS - E sub The adsorption energies of different MXenes with Li2S2 were obtained, where E total E represents the energy of the adsorption system. LiPS E is the molecular energy of Li2S2. sub The energy of the MXene base.
[0042] S5. Determination of the adsorption energy screening range and screening of MXenes:
[0043] The design principle of lithium-sulfur battery host materials requires moderate adsorption energy. Excessive energy will lead to difficulties in the desorption of lithium polysulfides. Therefore, the adsorption structure needs to be intact and not undergo significant deformation. By analyzing the optimization results of step 3 and the adsorption energy obtained in step 4, the upper limit of the adsorption energy intensity was determined.
[0044] If the adsorption energy is too weak, effective anchoring is impossible. Therefore, the adsorption between the host material and lithium polysulfides must be stronger than that between the electrolyte and lithium polysulfides. The adsorption energies of commonly used organic electrolytes in lithium-sulfur batteries, dioxolane (DOL), dimethyl ether (DME), and Li2S2 were calculated using DFT, and the lower limit of the adsorption energy strength was determined.
[0045] Candidate materials whose adsorption energies meet the requirements are screened according to the adsorption energy range.
[0046] S6: Further verification of the candidate material was performed by conducting ab initio molecular dynamics simulations of its adsorption structure at 300 K for 10 ps to verify the dynamic stability of the adsorption system at room temperature.
[0047] S7: For kinetically stable candidate materials, the adsorption configurations of *S8, *Li2S8, *Li2S6, *Li2S4, *Li2S2, and *Li2S on their corresponding MXenes during the SRR process were constructed. The Gibbs free energy formula ΔG=ΔE+ΔE was used. ZPE - TΔS calculates the free energy of each stage of the sulfur reduction reaction, where ΔE represents the change in the ground-state energy of the system before and after adsorption. ZPE The change in zero-point energy is represented by ΔS, the entropy change is represented by T, and the temperature is represented by 298 K. Based on the corresponding free energy step diagram, its catalytic performance was analyzed, and the high-performance MXene lithium-sulfur battery host material was finally selected.
[0048] The SRR mechanism is as follows:
[0049] *S8 + 2Li + + 2e - → *Li2S8 (Equation 1)
[0050] 3*Li₂S₈ + 2Li + + 2e - → 4*Li2S6 (Equation 2)
[0051] 2*Li₂S₆ + 2Li + + 2e - → 2*Li2S4 (Equation 3)
[0052] *Li₂S₄ + 2Li + + 2e - → 2*Li2S2 (Equation 4)
[0053] *Li₂S₂ + 2Li + + 2e - → 2*Li2S (Equation 5)
[0054] Example 1
[0055] The following describes the application of this method using one implementation as an example; the process is as follows: Figure 1 As shown. Includes the following steps:
[0056] Step 1. Collect 155 terminally symmetric MXene crystal structures (terminal types: -O, -F, -Cl, -Br) from the aNANT functional materials database. Model Li₂S₂ using the VESTA package. Optimize the structure of all MXene models using the VASP package to obtain the MXene substrate energy, and simultaneously optimize the structure of Li₂S₂ to obtain the adsorption molecule energy.
[0057] Step 2. Using the optimized MXene structure from Step 1 as a substrate and Li2S2 as the adsorbent molecule, construct the corresponding adsorption structure model using a Python script.
[0058] Step 3. Use the VASP software package to optimize the adsorption structure constructed in Step 2 to obtain a reasonable adsorption configuration and the total energy of the adsorption system.
[0059] Step 4. Analyze the energy calculated in Steps 1 and 3, and calculate E according to the adsorption energy formula. ads = E total -E LiPS - E sub The adsorption energies of 155 MXenes with Li2S2 were obtained, with the adsorption energy distribution ranging from approximately 0.5 eV to -10.5 eV.
[0060] Step 5. Determine the adsorption energy screening range. The adsorption energy should be moderate. If it is too strong, it will damage the lithium polysulfide molecules and prevent subsequent desorption. Analyze the optimization results of the adsorption structure in Step 3. The adsorption energy needs to be greater than -3.2 eV. At the same time, the adsorption needs to be stronger than the adsorption of Li2S2 molecules by electrolyte molecules. Calculate the adsorption energy of DOL-Li2S2 and DME-Li2S2 by DFT. The calculation results show that the adsorption energy needs to be less than -1 eV. Therefore, the target adsorption energy range is -3.2 eV to -1 eV. Based on this range, 86 MXene materials with adsorption energies that meet the requirements are initially screened.
[0061] Step 6. Based on the screening results, there were MXenes that met the requirements for each type of terminal. Three MXenes were randomly selected for each terminal, and finally 12 MXenes were selected as representative candidates. Molecular dynamics simulations were performed at 300K for 10 ps to verify the kinetic stability of the corresponding adsorption structures of the candidates.
[0062] Step 7. From the candidates exhibiting kinetic stability, one of each terminal was selected, for a total of 4 candidates. The energies of the *S8, *Li2S8, *Li2S6, *Li2S4, *Li2S2, and *Li2S structures corresponding to these 4 MXenes were calculated. The free energy change ΔG of each path during the SRR process was calculated, and the free energy diagram of the SRR reaction path was plotted as follows. Figure 1 As shown, ScWCCl2 and YNbNBr2 exhibit better catalytic activity, and their corresponding structures are as follows. Figure 2 As shown.
[0063] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications and improvements made within the scope of the principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for screening MXenes as host materials for lithium-sulfur batteries, characterized in that, Includes the following steps: Step S1: Collect MXene structures and model lithium polysulfide molecules using VESTA. Optimize the structure of the target MXene material and lithium polysulfide molecules using first-principles calculation software to obtain stable structures and acquire the corresponding system energies. Step S2: Using the MXene structure optimized in step S1 as a substrate, construct the adsorption structure of lithium polysulfide molecules on different MXenes; Step S3: Perform structural optimization calculations on the adsorption structure constructed in step S2 using first-principles calculation software to obtain a reasonable adsorption configuration and acquire the energy of the adsorption system. Step S4: Combine the energy obtained in step S1 and the adsorption system energy obtained in step S3 to calculate the adsorption energy of different MXenes with lithium polysulfide molecules. Step S5: Determine the target adsorption energy range through DFT calculation and analysis, and screen materials according to the target adsorption energy range to obtain preliminary candidate materials; Step S6: Verify the dynamic stability of the preliminary candidate material by performing ab initio molecular dynamics simulations using first-principles calculation software; Step S7: For kinetically stable candidate materials, use the Gibbs free energy formula ΔG=ΔE+ΔE ZPE -TΔS was used to calculate the free energy of each stage of the sulfur reduction reaction; its catalytic performance was analyzed based on the corresponding free energy step diagram, and finally, the high-performance MXene lithium-sulfur battery host material was selected. Where ΔE represents the change in the ground-state energy of the system before and after adsorption, ΔE ZPE ΔS represents the change in zero-point energy, ΔS represents the entropy change, and T represents the temperature, with a value of 298 K.
2. The method according to claim 1, characterized in that, In step S5, the upper limit of the adsorption energy intensity is greater than -3.2 eV; the lower limit of the adsorption energy intensity is less than -1 eV; and the target adsorption energy range is from -3.2 eV to -1 eV.
3. The method according to claim 2, characterized in that, The method for determining the target adsorption energy range includes: The theoretical upper limit of the adsorption energy without destruction of the lithium polysulfide molecular structure was determined by DFT calculation, and the theoretical lower limit of the adsorption energy was determined by DFT calculation of the adsorption energy of Li2S2 molecules by two commonly used organic electrolytes in lithium-sulfur batteries, dioxolane DOL and dimethyl ether DME. Based on this, a safety buffer value was added to determine the final screening range.
4. The method according to claim 1, characterized in that, In step S6, the ab initio molecular dynamics simulation is performed for at least 10 ps at 300 K.
5. The MXene screening method for lithium-sulfur battery host materials according to claim 1, characterized in that, In step S7, the sulfur reduction reaction process includes the following reaction pathway: *S8 + 2Li + + 2e - → *Li2S8 (Equation 1) 3*Li2S8 + 2Li + + 2e - → 4*Li2S6 (Equation 2) 2*Li2S6 + 2Li + + 2e - → 2*Li2S4 (Equation 3) *Li2S4 + 2Li + + 2e - → 2*Li2S2 (Equation 4) *Li2S2 + 2Li + + 2e - → 2*Li2S (Equation 5).
6. The MXene screening method for lithium-sulfur battery host materials according to claim 1, characterized in that, In step S1, the collection of MXene crystal structures includes collecting MXene crystal structures with terminal types of -O, -F, -Cl, and -Br.
7. The MXene screening method for lithium-sulfur battery host materials according to claim 1, characterized in that, Step 4 specifically involves: Combining the energy obtained in step S1 and the adsorption system energy obtained in step S3, the adsorption energy is calculated using the formula E. ads =E total - E LiPS - E sub The adsorption energies of different MXenes and lithium polysulfide molecules were obtained, among which E total E represents the energy of the adsorption system. LiPS For the energy of lithium polysulfide molecules, E sub The energy of the MXene base.
8. The MXene screening method for lithium-sulfur battery host materials according to any one of claims 1-4 and 6-7, characterized in that, The lithium polysulfide molecule is Li2S2, and the lithium polysulfide species involved in the sulfur reduction reaction pathway in step S7 include S8, Li2S8, Li2S6, Li2S4, Li2S2 and Li2S.
9. A lithium-sulfur battery host material, characterized in that, Obtained by the MXene screening method for lithium-sulfur battery host materials as described in any one of claims 1 to 7.