A Li 18 CdPb3O 16 Design method of a model and its application

Abstract

The application belongs to the technical field of solid-state batteries, and particularly relates to a Li 18 CdPb3O 16 Model design method and application thereof. Through theoretical calculation, the application precisely regulates and controls doped Cd 2+ and Li + Concentration, so that the Li 18 CdPb3O 16 Material has high ion conductivity (room temperature >= 1 mS / cm), high oxidation limit comparable to LLZO, and excellent interface compatibility with LiCoO2 or LiNiO2.

Description

Technical Field

[0001] This invention belongs to the field of solid-state battery technology, specifically relating to a method for constructing Li based on first-principles calculations. 18 CdPb3O 16 Model design methods and their applications. Background Technology

[0002] All-solid-state lithium batteries, with their potential for both high safety and high energy density, have become the core development direction of next-generation energy storage technology. Solid-state electrolytes, as a key component, directly determine the overall electrochemical characteristics of the battery. Oxide solid-state electrolytes have become a research hotspot due to their excellent thermal stability, good chemical compatibility, and wide electrochemical window. Currently, typical oxide electrolytes include garnet-type (LLZO), perovskite-type (LLTO), and nASICON-type (LATP), each with its own advantages in specific performance dimensions. However, with the increasing demand for high energy density, ideal electrolyte materials must simultaneously meet the requirements of high room-temperature lithium-ion conductivity (≥10). -3 Properties such as S / cm, adaptability to high-voltage cathodes, and good interfacial matching with electrodes are essential. However, the types of oxide electrolytes available remain limited, and existing systems often fail to fully meet these performance requirements: some materials have high ionic conductivity but insufficient compatibility with high-voltage cathodes, while others exhibit excellent stability but low room-temperature conductivity. This dilemma of synergistic performance optimization highlights the urgent need to develop novel oxide solid-state electrolytes. Summary of the Invention

[0003] In view of this, the present invention provides a method for constructing Li based on first-principles calculations. 18 CdPb3O 16 The design method and application of the model: The novel oxide solid electrolyte provided by this invention has high ionic conductivity, high intrinsic oxidation limit and good interface compatibility with cathode materials.

[0004] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for constructing Li based on first-principles calculations. 18 CdPb3O 16 The model's approach includes the following steps: (1) Obtain the unit cell model of Li4PbO4 from the Infinite Crystal Database (ICSD); (2) Based on the principles of ionic radius matching and charge compensation, using Cd 2+ Partial Pb in the unit cell model of Li4PbO4 4+ Sites, while introducing additional Li + Occupy Cd 2+ and Pb 4+The interstitial sites between them yielded a stoichiometric ratio of Li. 18 CdPb3O 16 The target components; (3) Generation of Li 18 CdPb3O 16 The composition consists of all atomic configurations with unequal symmetries, the Ewald energy of each atomic configuration is calculated, and the atomic configuration with the lowest energy is selected as the candidate configuration. (4) Based on the structural relaxation of density functional theory, optimize the atomic positions and unit cell parameters of the candidate configurations, and select the candidate configuration with the lowest total energy as the Li configuration. 18 CdPb3O 16 Model.

[0005] Preferably, the symmetry-inequivalent atomic configurations include those with Cd 2+ In Pb 4+ Configurations obtained from different site distribution patterns and Li + Configurations obtained by different occupancy patterns at interstitial sites.

[0006] Preferably, the specific steps of step (2) are as follows: in Li 16 Pb4O 16 In the unit cell model, with 1 Cd 2+ Replace 1 Pb 4+ At the same time, two Li + Occupying interstitial sites, resulting in a stoichiometric ratio of Li 18 CdPb3O 16 The target components.

[0007] The present invention also provides a Li 18 CdPb3O 16 The material has the chemical composition Li 18 CdPb3O 16 Its unit cell configuration is Li 18 CdPb3O 16 The unit cell configuration of the model; the Li 18 CdPb3O 16 The model is the Li obtained by constructing the method described above. 18 CdPb3O 16 Model.

[0008] The present invention also provides the Li described in the above technical solution. 18 CdPb3O 16 Application of materials in all-solid-state lithium batteries.

[0009] Preferably, the Li 18 CdPb3O 16The material can be directly applied as a solid electrolyte layer in all-solid-state lithium batteries, or as a coating layer to modify the cathode material.

[0010] Preferably, the positive electrode material includes LiCoO2 or LiNiO2.

[0011] This invention achieves precise control of Cd doping through theoretical calculations. 2+ With Li + Concentration was used to obtain Li₂ with high ionic conductivity (≥1 mS / cm at room temperature), high oxidation limit comparable to LLZO, and excellent interfacial compatibility with LiCoO₂ / LiNiO₂. 18 CdPb3O 16 Material.

[0012] Compared with existing oxide solid electrolytes, the present invention has the following advantages: (1) High room temperature lithium-ion conductivity: The Li of this invention 18 CdPb3O 16 The material is obtained through precise Cd 2+ Doping with Li + With optimized concentration, the predicted room-temperature ionic conductivity reaches 1.3 mS / cm. AIMD simulations show that the migration activation energy is as low as 0.30 eV, and the three-dimensional diffusion channels synergistically enhance rate performance.

[0013] (2) High oxidation limit: Generalized phase diagram analysis shows that the Li of this invention 18 CdPb3O 16 The intrinsic oxidation decomposition potential of the material is approximately 2.9 V (vs. Li). + / Li), which has an oxidation limit similar to that of LLZO.

[0014] (3) Theoretical calculations show that the present invention Li 18 CdPb3O 16 When the material comes into contact with LiCoO2 and LiNiO2, the interfacial reaction energy is low and the element interdiffusion tendency is small, which effectively suppresses the formation of high-resistivity impurity phases and ensures long-term cycling stability.

[0015] (4) Good thermodynamic stability: lower energy above hull (E hull The numerical values ​​indicate that the material is thermodynamically stable (45 meV / atom), ensuring the structural integrity of the material under battery operating conditions.

[0016] (5) Theoretical guidance for efficient research and development: This invention is based entirely on first-principles calculation design. Through systematic doping design, configuration enumeration, AIMD simulation and interface analysis, it provides precise targeting for subsequent experimental synthesis, greatly shortens the research and development cycle of new materials and reduces the experimental cost of traditional trial and error methods. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the embodiments will be briefly described below.

[0018] Figure 1 For Li 18 CdPb3O 16 The modeling process is illustrated in the following diagram: (a) shows the crystal structure of Li4PbO4; (b) shows the lithium-ion sites obtained based on topological analysis; (c) shows the adjustment of the Pb, Cd, and Li occupancy ratios; and (d) shows the Li4PbO4 crystal structure obtained after ordering. 18 CdPb3O 16 Model; green spheres represent Li, black spheres represent Pd, and magenta spheres represent Cd; Figure 2 For Li at different temperatures 18 CdPb3O 16 Arrhenius fitting plot of lithium-ion diffusion in medium; Figure 3 For Li under different lithium chemical potentials 18 CdPb3O 16 The reaction energy change graph; Figure 4 For Li 18 CdPb3O 16 Van Hoff correlation function plot of lithium-ion diffusion in the middle. Detailed Implementation

[0019] This invention provides a method for constructing Li based on first-principles calculations. 18 CdPb3O 16 The model design methodology includes the following steps: (1) Obtain the unit cell model of Li4PbO4 from the Wuji Crystal Database; (2) Based on the principles of ionic radius matching and charge compensation, using Cd 2+ Partial Pb in the unit cell model of Li4PbO4 4+ Sites, while introducing additional Li + Occupy Cd 2+ and Pb 4+ The interstitial sites between them yielded a stoichiometric ratio of Li. 18 CdPb3O 16 The target components; (3) Generation of Li 18 CdPb3O 16 The composition consists of all atomic configurations with unequal symmetries, the Ewald energy of each atomic configuration is calculated, and the atomic configuration with the lowest energy is selected as the candidate configuration. (4) Based on the structural relaxation of density functional theory, optimize the atomic positions and unit cell parameters of the candidate configurations, and select the candidate configuration with the lowest total energy as the Li configuration. 18 CdPb3O 16 Model.

[0020] The present invention obtains the unit cell model of Li4PbO4 from the Wuji Crystal Database.

[0021] In this invention, the structural data contained in the unit cell model of Li4PbO4 include atomic positions and unit cell parameters.

[0022] This invention is based on the principles of ionic radius matching and charge compensation, utilizing Cd 2+ Replacing part of the Pb in the Li4PbO4 unit cell model 4+ Sites, while introducing additional Li + Occupy Cd 2+ and Pb 4+ The interstitial sites between them yielded a stoichiometric ratio of Li. 18 CdPb3O 16 The target components.

[0023] In this invention, Li 18 CdPb3O 16 The specific steps for obtaining the target composition can be as follows: in Li 16 Pb4O 16 In the unit cell model, with 1 Cd 2+ Replace 1 Pb 4+ At the same time, two Li were introduced. + Occupying interstitial sites, resulting in a stoichiometric ratio of Li 18 CdPb3O 16 The target components.

[0024] In this invention, the symmetry-inequivalent atomic arrangement configurations include those with Cd 2+ In Pb 4+ Configurations obtained from different site distribution patterns and Li + Configurations obtained by different occupancy patterns at interstitial sites.

[0025] Generate Li 18 CdPb3O 16 For all symmetry-inequivalent atomic configurations, calculate the Ewald energy of each configuration and select the configuration with the lowest energy as the candidate configuration. Based on density functional theory structural relaxation, optimize the atomic positions and cell parameters of the candidate configurations, and select the candidate configuration with the lowest total energy as the Li configuration. 18 CdPb3O 16 Model.

[0026] In this invention, Li is obtained. 18 CdPb3O 16 Following the model, it also includes Li 18 CdPb3O 16 The thermodynamic stability of the model is assessed by calculating the model's formation energy and energy convex hull distance (E). hull ), to evaluate the thermodynamic stability of the material.

[0027] In this invention, Li is obtained. 18 CdPb3O 16 Following the model, it also includes Li 18 CdPb3O 16 The model can predict lithium-ion diffusion performance using the following method: [The text abruptly ends here, likely due to an incomplete sentence or a formatting error.] 18 CdPb3O 16 The model performs ab initio molecular dynamics (AIMD) simulations, calculating the mean square displacement (MSD) of lithium ions at multiple temperatures (e.g., 900–1500 K). The self-diffusion coefficient D at each temperature is obtained through linear fitting of the MSD. The migration activation energy Ea is obtained by fitting the diffusion coefficient versus temperature according to the Arrhenius equation. The Nernst-Einstein equation is then extrapolated to room temperature (300 K) to predict the Li-ion migration efficiency. 18 CdPb3O 16 ionic conductivity at room temperature.

[0028] In this invention, Li is obtained. 18 CdPb3O 16 Following the model, it also includes Li 18 CdPb3O 16 The model can predict the electrochemical window using the following method: Calculate the Li using the Grand Potential Phase Diagram method. 18 CdPb3O 16 The intrinsic electrochemical window of the material; by changing the lithium chemical potential (μ Li The phase stability of the material under different voltages was analyzed to determine the oxidation limit.

[0029] In this invention, Li is obtained. 18 CdPb3O 16 Following the model, it also includes Li 18 CdPb3O 16 The model can be evaluated for interface compatibility using methods such as: calculating Li based on a pseudo-binary system and a materials genome database using the pymatgen package. 18 CdPb3O 16 The decomposition energy ΔE_D of LiCoO2 and LiNiO2.

[0030] The present invention also provides a Li 18 CdPb3O 16 The material has the chemical composition Li 18 CdPb3O 16 Its unit cell configuration is Li 18 CdPb3O 16 The unit cell configuration of the model; the Li 18 CdPb3O 16 The model is the Li obtained by constructing the method described above. 18 CdPb3O 16 Model.

[0031] The Li provided by this invention 18 CdPb3O 16 The material was obtained by Cd oxidizing the Pb sites in Li4PbO4. 2+ Heterovalent substitution, and the introduction of additional lithium ions to maintain charge balance, forms a stable solid solution structure, which has the following advantages: (1) It has a crystal structure similar to Li4PbO4, with Cd occupying Pb sites to form Li 18 CdPb3O 16 The ordered structure allows lithium ions to be distributed in the interstitial spaces of the crystal lattice, forming three-dimensional or quasi-three-dimensional diffusion channels. (2) Cd doping induces local structural distortion, optimizes lithium ion distribution and migration path, and reduces migration energy barrier; (3) High lithium ion concentration provides a structural basis for high ionic conductivity.

[0032] The present invention also provides the aforementioned Li 18 CdPb3O 16 Application of materials in all-solid-state lithium batteries.

[0033] In this invention, the Li 18 CdPb3O 16 The material can be directly applied as a solid electrolyte layer in all-solid-state lithium batteries, or as a coating layer to modify the cathode material.

[0034] In this invention, the positive electrode material includes LiCoO2 or LiNiO2. In this invention, Li... 18 CdPb3O 16 The material can be used as a coating layer to modify the surface of the cathode material, thereby improving the interfacial stability between the cathode material and the electrolyte.

[0035] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the accompanying drawings and embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0036] Example 1 Li 18 CdPb3O 16 Theoretical construction and stability verification of crystal structure Based on Li4PbO4 as the initial structural basis, a Li-type matrix containing 16 Li, 4 Pb, and 16 O atoms was constructed. 16 Pb4O 16 Unit cell. With 1 Cd 2+ Replace 1 Pb 4+ And introduce 2 additional Li + Occupy the gap position to obtain Li 18 CdPb3O 16 Composition, generating Li 18 CdPb3O 16 All atomic configurations with non-equivalent symmetries (in Cd) 2+ In Pb 4+ Configurations obtained from different site distribution patterns and Li + Configurations obtained from different occupancy modes of interstitial sites were initially screened using Ewald energy. The configuration with the lowest energy was selected as the candidate configuration. DFT structural relaxation was performed on the candidate configurations to optimize the atomic positions and unit cell parameters. The candidate configuration with the lowest total energy was selected as the Li configuration. 18 CdPb3O 16 Schematic diagram of the model. Figure 1 For Li 18 CdPb3O 16 Modeling process, where (a) is a schematic diagram of the crystal structure of Li4PbO4; (b) is a process for obtaining a structure capable of accommodating Li based on topological analysis. + (c) Sites; (d) Adjusting the occupancy ratio of Pb, Cd, and Li; (e) Obtaining Li after ordering. 18 CdPb3O 16 (Model: Green spheres represent Li, black spheres represent Pd, and magenta spheres represent Cd.) DFT structural relaxation was performed on the candidate configurations. The optimized unit cell parameters increased, indicating a broadening of lithium-ion diffusion channels, a change that favors lithium-ion diffusion. Calculations revealed that Li... 18 CdPb3O 16 E hull = 45 meV / atom, indicating that the material has good thermodynamic stability.

[0037] Example 2 AIMD simulation of lithium-ion diffusion performance For Li 18 CdPb3O 16A stable 2×2×1 supercell was constructed for AIMD simulations. Simulation temperatures ranged from 900 to 1500 K, with a time step of 2 fs and a total simulation duration of 60 ps. The lithium-ion self-diffusion coefficient at each temperature was calculated using MSD. The activation energy for lithium-ion diffusion, Ea = 0.3 eV, was obtained through Arrhenius fitting. Extrapolation of the Nernst-Einstein equation to 300 K yielded a room-temperature ionic conductivity σ = 1.3 × 10⁻⁶. -3 S / cm, reaching the order of 1 mS / cm ( Figure 2 This confirms its excellent ion transport performance. Based on the van Hoff correlation function, it is shown that lithium ion diffusion in this structure is mainly cooperative diffusion. Figure 4 ).

[0038] Example 3 Broad-potential phase diagram analysis of the electrochemical window Calculate Li using the generalized phase diagram method 18 CdPb3O 16 The intrinsic electrochemical window of the material. By changing the lithium chemical potential (μ Li The decomposition products of the material under different voltages were analyzed. The results showed that its intrinsic oxidation decomposition potential was approximately 2.88 V (vs. Li). + / Li), comparable to the theoretical oxidation limit of LLZO ( Figure 3 ).

[0039] Example 4 Compatibility assessment with LiCoO2 or LiNiO2 interface Based on the pseudo-binary system, calculate Li 18 CdPb3O 16 The decomposition energies of LiCoO2 and LiNiO2 were determined. The results indicate that Li... 18 CdPb3O 16 With LiCoO2 in the discharged state and Li in the charged state 0.5 The ΔE_D at the CoO2 interface are 0 meV / atom and -57.14 meV / atom, respectively; compared with LiNiO2 in the discharge state and Li in the charge state... 0.5 The NiO2 interface ΔE_D values ​​are 0 meV / atom and -48.12 meV / atom, respectively. This indicates that the material has excellent intrinsic chemical compatibility with layered oxide cathodes.

[0040] Li 0.5 CoO2 and Li 0.5 In NiO2, 0.5 represents the state of charge of LiCoO2.

[0041] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for constructing Li based on first-principles calculations 18 CdPb3O 16 The model design method is characterized by, Includes the following steps: (1) Obtain the unit cell model of Li4PbO4 from the Wuji Crystal Database; (2) Based on the principles of ionic radius matching and charge compensation, using Cd 2+ Partial Pb in the unit cell model of Li4PbO4 4+ Sites, while introducing additional Li + Occupy Cd 2+ and Pb 4+ The interstitial sites between them yielded a stoichiometric ratio of Li. 18 CdPb3O 16 The target components; (3) Generation of Li 18 CdPb3O 16 The composition consists of all atomic configurations with unequal symmetries, the Ewald energy of each atomic configuration is calculated, and the atomic configuration with the lowest energy is selected as the candidate configuration. (4) Based on the structural relaxation of density functional theory, optimize the atomic positions and unit cell parameters of the candidate configurations, and select the candidate configuration with the lowest total energy as the Li configuration. 18 CdPb3O 16 Model.

2. The design method as described in claim 1, characterized in that, The symmetry-inequivalent atomic configurations include those with Cd 2+ In Pb 4+ Configurations obtained from different site distribution patterns and Li + Configurations obtained by different occupancy patterns at interstitial sites.

3. The design method as described in claim 1, characterized in that, The specific steps of step (2) are as follows: in Li 16 Pb4O 16 In the unit cell model, with 1 Cd 2+ Replace 1 Pb 4+ At the same time, two Li were introduced. + Occupying interstitial sites, resulting in a stoichiometric ratio of Li 18 CdPb3O 16 The target components.

4. A Li 18 CdPb3O 16 The material is characterized by, The chemical composition is Li 18 CdPb3O 16 Its unit cell configuration is Li 18 CdPb3O 16 The unit cell configuration of the model; the Li 18 CdPb3O 16 The model is the Li obtained by constructing the method according to any one of claims 1 to 3. 18 CdPb3O 16 Model.

5. The Li according to claim 4 18 CdPb3O 16 Application of materials in all-solid-state lithium batteries.

6. The application as described in claim 5, characterized in that, The Li 18 CdPb3O 16 The material can be directly applied as a solid electrolyte layer in all-solid-state lithium batteries, or as a coating layer to modify the cathode material.

7. The application as described in claim 5, characterized in that, The cathode material includes LiCoO2 or LiNiO2.

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