2D MoB electrode material containing double-vacancy defect and performance regulation and control method thereof

Abstract

The invention belongs to the field of electrochemical energy storage and material calculation design, and discloses a 2D MoB electrode material containing a double-vacancy defect and a performance regulation and control method of the 2D MoB electrode material, and the interior of the electrode material has a Mo-Mo double-vacancy defect configuration with the most stable thermodynamics. The defect is induced to generate an asymmetric chemical environment on the upper and lower surfaces of the material: the vacancy center of the upper surface is a strong adsorption site, and the top of the B atom of the lower surface is a medium adsorption site. The adsorption difference directly causes significant anisotropy of lithium ion diffusion, and the diffusion energy barrier (about 0.410 eV) of the lower surface channel is far lower than the diffusion energy barrier (about 0.833 eV) of the upper surface channel, thereby becoming an optimal path for rapid ion transmission. The invention further provides a performance prediction method based on first principle calculation, a quantitative association rule of'strong adsorption-high diffusion energy barrier 'is established through systematic defect configuration screening and adsorption energy and diffusion energy barrier calculation, and a clear theoretical guidance and design tool is provided for designing a high-performance two-dimensional electrode material through rational defect engineering.

Description

Technical Field

[0001] This invention belongs to, but is not limited to, the field of electrochemical energy storage and materials computational design technology, and particularly relates to a 2D MoB electrode material containing double vacancy defects and its performance regulation method. Background Technology

[0002] With the rapid development of renewable energy transition and the electric vehicle industry, high-energy-density and high-power-density energy storage devices have become the core driving force for energy technology progress. Lithium-ion batteries, as the most important portable and electric vehicle energy storage solution, rely heavily on the electrochemical properties of electrode materials, especially the theoretical capacity, ion adsorption capacity, and ion diffusion kinetics of the anode material. Commonly commercialized graphite anodes limit battery energy density due to their relatively low theoretical capacity; therefore, developing anode materials with higher theoretical capacity and efficient ion transport is a key technological task. In this field, two-dimensional materials are considered highly promising electrode material platforms due to their high specific surface area, tunable electronic structure, and potential open ion channels. In particular, transition metal borides (MBenes), as a new member of the two-dimensional material family, have attracted widespread attention in the energy storage community due to their unique electronic and structural properties. Existing research shows that MBenes, as layered two-dimensional materials, not only possess excellent conductivity but also potentially provide abundant active sites, which are beneficial for ion adsorption and migration, making them promising for applications in metal-ion batteries, electrocatalysis, and other fields.

[0003] Among the transition metal borides, the theoretical performance of two-dimensional molybdenum boride (MBene) is particularly noteworthy. Related work has theoretically predicted the potential advantages of M2B2-like two-dimensional borides (such as Mo2B2) in battery applications, including higher theoretical specific capacity and lower diffusion barriers. Their minimum lithium-ion diffusion barrier has been calculated to be comparable to or even better than that of graphite and some MXene systems. However, existing literature mainly focuses on macroscopic performance predictions of perfect lattice materials, with in-depth analysis of the lithium-ion diffusion mechanism in perfect lattices still in its early stages, especially lacking a systematic understanding of the material performance under defect modulation. Furthermore, compared to two-dimensional material systems like MXene, theoretical studies in MBenes have demonstrated their potential for modulating electronic structure and enhancing active sites, but their ion adsorption behavior as electrode materials, the influence of defects on diffusion kinetics, and their correlation with diffusion channels remain poorly understood.

[0004] Against this backdrop, existing technologies suffer from key shortcomings. On the one hand, defect design in two-dimensional molybdenum boride materials is still in its early stages, with almost no quantitative comparisons of the effects of various defect configurations on lithium-ion adsorption and migration behavior found in publicly available data. On the other hand, how to construct a closed-loop correlation between the material's "defect configuration—ion adsorption energy—diffusion barrier," enabling designers to rationally predict and directionally optimize the material's electrochemical performance at the atomic scale, has not yet been systematically reported. Furthermore, existing technologies have almost no in-depth research or discussion on the thermodynamic stability, electronic structure changes, and specific impacts of double-vacancy defects in two-dimensional molybdenum boride on ion transport kinetics. This directly leads to a lack of operable design strategies and structure-property mechanisms in the development of high-performance energy storage electrode materials, thus hindering the further application of two-dimensional molybdenum boride in the field of high-performance lithium-ion battery anodes.

[0005] In summary, existing technologies have not yet provided a methodological framework and systematic understanding for quantitatively analyzing the impact of two-dimensional molybdenum boride defect structures on lithium-ion adsorption and diffusion behavior. This is precisely the technical problem that urgently needs to be solved in the design and optimization of high-performance energy storage materials. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a 2D MoB electrode material containing double vacancy defects and a method for regulating its performance.

[0007] The present invention is achieved as follows: a 2D MoB electrode material containing double vacancy defects, characterized in that the electrode material is a 2D MoB containing intrinsic double vacancy defects, wherein the double vacancy defects are Mo-Mo double vacancies.

[0008] Furthermore, the formation energy of the Mo-Mo double vacancy is the lowest among all types of double vacancy defects in 2D MoB, and its binding energy is positive.

[0009] Furthermore, the presence of the Mo-Mo double vacancy creates an asymmetric chemical environment on the upper and lower surfaces of 2D MoB, wherein the upper surface region where the double vacancy is located forms a strong adsorption site, and the top of the B atom on the lower surface forms a moderate adsorption site; 2D MoB containing the Mo-Mo double vacancy maintains a metallic electronic structure.

[0010] Furthermore, the diffusion barrier of lithium ions at the strong adsorption sites is higher than that at the medium adsorption sites, making the diffusion kinetics of lithium ions along the lower surface channels significantly better than those along the upper surface channels.

[0011] Another objective of this invention is to provide a method for screening defect configurations in 2D MoB electrode materials containing double vacancy defects, the method comprising the following steps:

[0012] S1: Based on first-principles calculations, a 2D MoB double-vacancy defect model is constructed, which includes different element types and atomic arrangements.

[0013] S2: Calculate and compare the formation energy of all defect models in step S1, and select the stable double-vacancy configuration with the lowest formation energy.

[0014] S3: Calculate the binding energy of the stable double-vacancy configuration and analyze the interaction properties between its constituent single vacancy sites.

[0015] Another objective of this invention is to provide a method for predicting the ion transport performance of 2D MoB electrode materials containing double vacancy defects, the method comprising the following steps:

[0016] S1: On the Mo-Mo double-vacancy stable configuration, the system searches for stable adsorption sites for lithium ions and calculates their adsorption energies.

[0017] S2: Using the stable adsorption sites determined in step S1 as the initial state, the diffusion barrier of ions in different migration paths is calculated using the climbing elastic band method.

[0018] S3: Based on the results of steps S1 and S2, establish the correlation between adsorption energy and diffusion barrier, evaluate the specific impact of the defect structure on ion transport dynamics, and identify the optimal diffusion channel.

[0019] Furthermore, in step S1, the adsorption site includes at least the vacancy center on the upper surface of the double vacancy site and the top of the B atom on the lower surface; in step S2, the anisotropy of ion diffusion is quantitatively revealed by comparing the diffusion energy barriers of different surface directions or paths.

[0020] Furthermore, the calculations are implemented based on the first-principles CASTEP module, the exchange correlation functional is GGA-PBE, and the van der Waals interactions are corrected using the DFT-D method.

[0021] Furthermore, the plane wave cutoff energy was set to 350 eV, and the k-point grid was set to 3×3×1; during the structural optimization process, the atomic force convergence criterion was 0.01 eV / Å, and the energy convergence criterion was 5×10⁻⁶. -6 eV.

[0022] Furthermore, the performance prediction method described herein incorporates a 15 Å vacuum layer along the z-direction to prevent interlayer interactions.

[0023] Based on the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solution to be protected by this invention are as follows:

[0024] First, this invention, through systematic first-principles calculations, reveals the key configuration of intrinsic double-vacancy defects in 2D MoB and its unique regulatory mechanism on lithium-ion storage behavior, which has the following outstanding advantages and innovations compared with the prior art:

[0025] (1) For the first time, a stable defect configuration has been clearly identified, providing a precise target for experimental preparation: Unlike existing studies that mostly focus on perfect 2D MoB or only discuss the influence of "defects" in general terms, this invention, through precise calculations, clearly points out for the first time that Mo-Mo double vacancies are the most thermodynamically stable and most likely dominant double vacancy defect type in 2D MoB. This provides a clear theoretical target and screening basis for the targeted introduction or characterization of this specific defect in experiments (such as ion irradiation, chemical etching, etc.), overcoming the problem of "ambiguous target" in traditional defect research.

[0026] (2) This invention reveals a new mechanism of "defect-induced surface asymmetry" and opens up a new dimension of performance regulation: The present invention finds that the presence of Mo-Mo double vacancies can break the symmetry of the upper and lower surfaces of two-dimensional materials, inducing adsorption sites with very different chemical properties (strong adsorption at vacancy centers on the upper surface vs. moderate adsorption at boron sites on the lower surface). This discovery goes beyond the traditional understanding that defects are only regarded as an increase in uniform active sites, and proposes a new idea of ​​achieving surface functional partitioning through a single defect, providing the possibility of constructing diversified reaction microenvironments within a single material.

[0027] (3) A quantitative structure-activity relationship of "adsorption-diffusion" was established, enabling rational prediction and design of performance: This invention did not stop at observing the adsorption phenomenon, but further quantitatively correlated the adsorption strength (thermodynamics) with the diffusion barrier (kinetics), establishing a clear physical law that "strong adsorption leads to a high diffusion barrier". Based on this law, this invention predicted and confirmed that lithium ions exhibit significant diffusion anisotropy in defective MoB, with the lower surface channel (diffusion barrier 0.410 eV) having a greater kinetic advantage than the upper surface channel (0.833 eV). This provides a precise design principle for achieving a balance between "high capacity" and "fast charge-discharge" performance of electrode materials: that is, by controlling defects, a "strong adsorption-high capacity region" and a "moderate adsorption-fast diffusion channel" are consciously constructed in the material.

[0028] (4) A complete computational design method from defect screening to performance prediction is provided, which greatly improves R&D efficiency: This invention forms a complete computational research paradigm from "defect configuration stability screening (formation energy, binding energy)" → "microscopic property evaluation (adsorption energy, electronic structure)" → "macroscopic performance prediction (diffusion barrier, anisotropy analysis, electrochemical performance)". This method is universal and can be extended to defect engineering research of other two-dimensional electrode materials, changing the R&D mode of new materials and performance optimization from "trial and error" to "rational design", which greatly shortens the R&D cycle and reduces R&D costs.

[0029] (5) It provides profound physical insights for the design of high-performance electrode materials: The core discovery of this invention is that the local chemical environment (determined by the type of defect) dominates the ion diffusion dynamics by regulating the adsorption intensity—a universal physical mechanism. This understanding not only applies to explaining the phenomena in MoB, but also provides a key theoretical framework for understanding the ion transport behavior in other complex electrode materials (such as heterojunctions and doped materials), and has important scientific guiding value.

[0030] Second, this invention systematically fills a critical, multi-layered technological gap in the field of two-dimensional transition metal borides (MBenes), particularly in the defect engineering of molybdenum boride (MoB) electrode materials. Existing research mainly focuses on preliminary predictions of the macroscopic properties of perfect lattice materials or general discussions of the positive impact of "defects," exhibiting three core limitations: First, the target is vague, never clearly defining which intrinsic double-vacancy configuration is thermodynamically most stable and most likely to dominate material behavior, resulting in a lack of precise theoretical targets for experimental preparation; second, the mechanism is unclear, lacking a complete causal chain explanation from microstructure to macroscopic properties regarding how defects quantitatively affect ion adsorption and migration by altering the local atomic and electronic environment, especially regarding the surface asymmetry that double vacancies may induce and its effects; third, the methodology is lacking, completely lacking a universal prediction and design method that can rationally design defect structures from the atomic scale to synergistically optimize ion storage capacity (thermodynamics) and transport rate (kinetics). To address the aforementioned gaps, this invention achieves a systematic breakthrough, moving from "unknown" to "clearly defined," from "appearance" to "mechanism," and from "trial and error" to "design":

[0031] (1) At the defect identification level, the formation energies of three types of double vacancies, namely BB, Mo-B and Mo-Mo, were compared using first-principles calculations. For the first time, it was clearly pointed out that the Mo-Mo double vacancy is the most thermodynamically stable intrinsic double vacancy type in 2D MoB (with a minimum formation energy of only 0.41 eV). This provides a definitive atomic-level target for the experimental targeted introduction or characterization of this specific defect through methods such as ion irradiation and chemical etching (Table 1 and ...). Figure 3 ).

[0032] (2) At the level of mechanism explanation, a novel physical mechanism of "defect-induced surface asymmetry" was revealed for the first time. Calculations show that the presence of Mo-Mo double vacancies actively breaks the symmetry between the upper and lower surfaces of the two-dimensional material, resulting in the vacancy centers on the upper surface becoming strong adsorption sites for lithium ions (adsorption energy -1.453 eV), while the tops of B atoms on the lower surface form medium adsorption sites (adsorption energy -0.622 eV), thus constructing "functional partitions" with distinct chemical properties within a single material. Figure 2 , Figure 6 (and Table 3).

[0033] (3) At the level of structure-activity relationship and performance prediction, a quantitative structure-activity relationship of "adsorption energy-diffusion barrier" was established for the first time, and a clear rule of "strong adsorption leads to high diffusion barrier" was discovered. Figure 8 Based on this, the significant diffusion anisotropy of lithium ions in defective MoB was predicted and confirmed for the first time: the diffusion barrier of the B atom channels on the lower surface (0.410 eV) is much lower than that of the vacancy channels on the upper surface (0.833 eV), thus clarifying the preferred path for achieving rapid ion transport. Figure 7 This provides a concrete theoretical solution to the fundamental contradiction of the difficulty in simultaneously achieving "high capacity" and "fast charge / discharge" performance in electrode materials—namely, utilizing specific defects to construct "strong adsorption storage regions" and "fast diffusion channel regions".

[0034] (4) At the methodological level, a complete and generalizable rational computational design paradigm has been formed and provided, covering the entire chain from "defect configuration stability screening (formation energy / binding energy)" to "microscopic property evaluation (adsorption energy / electronic structure)" and then to "macroscopic performance prediction and optimization channel identification (diffusion barrier / anisotropy)". Figure 1 (Process). This method completely shifts the research and development of such materials from the traditional "trial and error" approach to a "predictable and designable rational stage".

[0035] In summary, this invention is not a simple improvement on existing technologies, but rather a multi-dimensional and systematic innovation from basic cognition to top-level design, encompassing the precise identification of defective targets, the first revelation of new regulatory mechanisms, the establishment of quantitative structure-activity relationships, and the provision of rational design paradigms. It comprehensively fills the long-standing key technological gaps in this field, demonstrating outstanding substantive features and significant progress. Attached Figure Description

[0036] Figure 1 This is a flowchart illustrating the design and performance prediction of dual-vacancy battery anode materials provided in an embodiment of the present invention.

[0037] Figure 2This is a schematic diagram of a 2D MoB structure containing Mo-Mo double vacancies provided in an embodiment of the present invention, showing the asymmetric atomic environment of the upper and lower surfaces;

[0038] Figure 3 This is a bar chart comparing the formation energies of different double-vacancy configurations (BB, Mo-B, Mo-Mo) provided in the embodiments of the present invention.

[0039] Figure 4 This is the AIMD simulation temperature fluctuation curve of the "Mo-Mo-1" double-vacancy MoB at 300K provided in the embodiment of the present invention;

[0040] Figure 5 The electronic density of states diagram of 2D MoB containing Mo-Mo double vacancies provided in the embodiments of the present invention proves its metallic electronic structure;

[0041] Figure 6 This is a schematic diagram of the adsorption configuration of lithium ions at the optimal adsorption sites on the upper and lower surfaces of the Mo-Mo double vacancy, and the corresponding adsorption energy values ​​provided in the embodiments of the present invention.

[0042] Figure 7 This is a schematic diagram of the diffusion path of lithium ions along the vacancy channels on the upper surface and the B atom channels on the lower surface, and a corresponding diffusion barrier curve provided in an embodiment of the present invention.

[0043] Figure 8 The "adsorption energy (E)" provided in the embodiments of the present invention ads ) and diffusion barrier (E barrier The diagram illustrates the relationship between strong adsorption and high energy barriers. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0045] This invention provides a two-dimensional molybdenum boride (2D MoB) electrode material containing double-vacancy defects. The most stable intrinsic double-vacancy defect type in this material is molybdenum-molybdenum (Mo-Mo) double vacancy. This defect configuration has the lowest formation energy among all double-vacancy types, and its binding energy is positive, indicating a weak repulsive effect between the two Mo monovacancies, which thermodynamically tends to disperse.

[0046] The Mo-Mo double vacancies induce an asymmetric chemical environment and adsorption sites on the upper and lower surfaces of 2D MoB: the vacancy center on the upper surface is a strong adsorption site with an adsorption energy of approximately -1.453 eV for lithium ions; the top of the B atom on the lower surface is a medium adsorption site with an adsorption energy of approximately -0.622 eV for lithium ions.

[0047] Based on the above adsorption characteristics, lithium ions exhibit significant diffusion anisotropy in 2D MoB containing Mo-Mo double vacancies: diffusion from the strongly adsorbed upper surface vacancy center requires overcoming a high energy barrier of about 0.833 eV, while diffusion from the moderately adsorbed lower surface B atom sites requires only a low energy barrier of about 0.410 eV, indicating that the lower surface channel is the preferred path for achieving rapid ion transport.

[0048] This invention provides a method for predicting and controlling the performance of the above-mentioned electrode material, comprising the following steps:

[0049] S1: Defect Configuration Screening: Based on first-principles calculations, the system constructs double-vacancy models with different element combinations and relative positions in 2D MoB, where the different element combinations in 2D MoB are BB, Mo-B, and Mo-Mo; calculates and compares their formation energies, and screens out the thermodynamically most stable double-vacancy configuration, namely Mo-Mo double vacancy.

[0050] S2: Defect Interaction Analysis: Calculate the binding energy of the most stable double-vacancy configuration and analyze the interaction trend between its constituent single vacancy sites;

[0051] S3: Adsorption performance evaluation: Search for stable adsorption sites of lithium ions on the upper and lower surfaces of the most stable double-vacancy configuration model, calculate the adsorption energy, and determine strong and moderate adsorption sites.

[0052] S4: Diffusion kinetics prediction: Based on the stable adsorption configuration determined in step S3, the diffusion energy barrier between ions at different surface sites is calculated using the climbing elastic band (CI-NEB) method, revealing the diffusion anisotropy caused by the difference in adsorption strength.

[0053] S5: Performance Correlation and Regulation: Establish a quantitative correlation between adsorption energy and diffusion barrier to elucidate the microscopic mechanism by which defect structure affects ion transport performance; by comparing the energy barriers of different diffusion paths, indicate the direction of structural design for optimizing ion transport dynamics, such as preferentially utilizing the B atom channels on the lower surface.

[0054] The calculations are implemented based on the first-principles CASTEP module, the exchange correlation functional is GGA-PBE, and the van der Waals interactions are corrected using the DFT-D method.

[0055] The plane wave cutoff energy is set to 350 eV, and the k-point grid is set to 3×3×1; during the structural optimization process, the atomic force convergence criterion is 0.01 eV / Å, and the energy convergence criterion is 5×10⁻⁶. -6 eV.

[0056] To avoid interlayer interactions, a 15 Å vacuum layer was set along the z-direction.

[0057] The dynamic stability of the most stable defect configuration was verified by first-principles molecular dynamics simulations.

[0058] like Figure 1 As shown, this embodiment of the invention provides a method for screening the most stable double-vacancy defect configuration, including the following steps:

[0059] Structural optimization: A 3×3×1 supercell model of the perfect 2D MoB was constructed and geometrically optimized. All calculations used the PBE functional under the generalized gradient approximation (GGA) to describe the exchange-correlated potential, and van der Waals force correction was performed using the DFT-D method. The plane wave cutoff energy was set to 350 eV, and the k-point grid was set to 3×3×1. All-atom relaxation optimization was performed until the atomic force converged to 0.01 eV / Å and the energy converged to 5×10⁻⁶. -6 eV.

[0060] Based on the results of the perfect supercell model, initial models for various BB double vacancies, Mo-B double vacancies, and Mo-Mo double vacancies were constructed. Each type considered different relative positions between atoms, such as adjacent and second nearest neighbor.

[0061] Perform thorough geometric optimization on all defect models and calculate their total energy E. defect Using formula E form =E defect -E perfect +n×μ calculates the formation energy of each configuration, where E perfect denoted as the total energy of a perfect supercell, n is the number of atoms removed, and μ is the chemical potential of the corresponding atom.

[0062] Figure 2 A schematic diagram of a 2D MoB containing Mo-Mo double vacancies is shown, which intuitively presents the asymmetric atomic environment of the upper and lower surfaces.

[0063] The results are as follows Figure 3 As shown, the formation energies of all Mo-Mo double-vacancy configurations are significantly lower than those of BB and Mo-B double-vacancy configurations. Among them, the "Mo-Mo-1" configuration has the lowest energy, about 0.41 eV, and is identified as the most stable configuration.

[0064] To verify the kinetic stability of this most stable configuration at finite temperatures, ab initio molecular dynamics (AIMD) simulations were performed on the "Mo-Mo-1" model. The simulations were conducted in the NVT ensemble at 300 K, with a duration of 5 ps and a time step of 1 fs. Temperature fluctuations during the simulation are shown below. Figure 4 As shown, the temperature remained stable around the set value, and the structure did not collapse or reconstruct during the entire simulation. The AIMD simulation results indicate that the "Mo-Mo-1" double-vacancy configuration has good dynamic stability at room temperature, further supporting its possibility as an intrinsically stable defect.

[0065] To confirm whether 2D MoB containing Mo-Mo double vacancies retains the high electronic conductivity necessary for its use as an electrode material, this invention calculated its density of electronic states (DOS). The results are as follows: Figure 5 As shown, a non-zero, continuous electronic density of states exists near the Fermi level (energy zero), primarily contributed by Mo-d orbital electrons. This characteristic clearly confirms that the defective material retains its metallic electronic structure and has not opened its band gap to become semiconductor due to the introduction of double vacancies. Excellent electronic conductivity is fundamental to achieving fast charge transfer and good rate performance.

[0066] This invention provides a structure-property relationship analysis method for the above-mentioned 2D MoB electrode material containing double vacancy defects. The method is characterized by quantifying the binding energy of double vacancy sites and surface adsorption properties, thus confirming the interaction between single and double vacancy sites and their electrochemical effects from both energy and functional perspectives. Specifically, the method includes the following steps:

[0067] For the “Mo-Mo-1” configuration, two single-vacancy models corresponding to it are constructed in the same supercell and the energy is calculated.

[0068] According to formula E bind =E DV +E perfect -E SV1 -E SV2 Calculate the binding energy, where E DV To determine the optimal total energy of two vacancies, E perfect For the total energy of a perfect supercell, E SV1 With E SV2 The total energy of the single vacancy at sites 1 and 2 were calculated, and the binding energies were both approximately 0.456 eV, confirming the existence of weak repulsion between the two single vacancy sites.

[0069] Based on the optimized "Mo-Mo-1" model, the system searches for the adsorption configurations of lithium ions at multiple possible sites on the upper and lower surfaces, including vacancy centers, Mo atom top sites, and B atom top sites.

[0070] Li ions were added at a distance of 1.5 Å above the corresponding sites to obtain their adsorption model on the surface;

[0071] The adsorption structures obtained above were subjected to complete relaxation, and the adsorption energy E of each adsorption configuration was calculated. ads =E system+Li -E system -E Li The result is as follows Figure 6 As shown, the strongest adsorption site is the Mo vacancy center on the upper surface, with an adsorption energy of -1.453 eV, while the top B atom site on the lower surface is a medium adsorption site, with an adsorption energy of -0.622 eV.

[0072] This invention provides a method for predicting ion diffusion kinetics and analyzing anisotropy of the Mo-Mo double-vacancy 2D MoB electrode material, specifically including the following steps:

[0073] Based on the strongest adsorption site determined above (upper surface V) Mo Focusing on the intermediate adsorption sites (B atoms on the lower surface), the most stable adsorption configuration and the adjacent most stable adsorption configuration were selected from the stable adsorption model using Reaction Preview as the starting and ending states for migration, and were respectively used as reactants and products.

[0074] Based on the lowest energy configuration of the initial and final states, the transition state was calculated using the CI-NEB method, the migration barrier was analyzed, the optimal reaction pathway was obtained, and the diffusion behavior of Li ions in the vacancy structure was established.

[0075] Based on the CI-NEB method, the energy barrier for diffusion from the vacancy center was calculated to be approximately 0.833 eV, while the energy barrier for diffusion from the B atom sites on the lower surface was approximately 0.410 eV. Figure 7 ).

[0076] Plotting the correlation between adsorption energy and diffusion barrier data ( Figure 8 The results clearly demonstrate the linear relationship that "the stronger the adsorption, the higher the diffusion barrier," confirming from a kinetic perspective that the B atom channels on the lower surface are a superior ion transport pathway.

[0077] The specific application areas or related products of this invention.

[0078] 1. Specific application areas and related products of the present invention

[0079] The technical solution of this invention (including two-dimensional MoB materials with specific Mo-Mo double vacancy defects and their performance regulation methods) is mainly applied in the field of advanced electrochemical energy storage, specifically as a core electrode active material for manufacturing high-performance, fast-charging secondary ion batteries. Its directly related products and applications include:

[0080] (1) High energy density and high power density lithium-ion battery anode materials:

[0081] Product Form: The defective 2D MoB material can be used as the main active material, and together with conductive agents and binders, it can be made into a composite material slurry, which is then coated onto a metal foil current collector to form a battery negative electrode sheet.

[0082] Application scenarios: Directly used in next-generation consumer electronics devices (such as smartphones and laptops), designed to address the urgent need of these devices for batteries that simultaneously offer long battery life and fast charging capabilities.

[0083] (2) Negative electrode materials for sodium-ion and potassium-ion batteries:

[0084] Product form: Similar to the above, it is used as a negative electrode active material.

[0085] Application scenarios: Given the universality of the "defect-regulated ion transport" mechanism revealed in this invention, this material system, after adaptability studies, can be extended to sodium, potassium and other ion battery systems for large-scale energy storage scenarios with higher requirements for cost sensitivity or resource abundance.

[0086] (3) High-performance supercapacitor electrode materials:

[0087] Product form: Utilizing its high specific surface area, metallic conductivity and tunable surface adsorption properties, it can be used as an electrode material for electric double layer capacitors or pseudocapacitive capacitors.

[0088] Application scenarios: Used in fields requiring extremely high power density and ultra-long cycle life, such as energy recovery systems and instantaneous high-power power supply equipment.

[0089] (4) Core components of multifunctional composite electrode materials:

[0090] Product Form: Using the 2D MoB defect material of this invention as a framework or substrate with high conductivity and high ion permeability, it is combined with high-capacity active materials such as silicon to form a composite anode material with an integrated structure of "conductive-buffered-fast ion channel".

[0091] Application scenarios: It is used to solve the fundamental problems of huge volume expansion and slow ion diffusion in ultra-high capacity anode materials such as silicon-based materials during charging and discharging, thereby improving their cycle stability and rate performance.

[0092] 2. Specific Implementation Path and Performance Prediction Scheme

[0093] To clearly and completely demonstrate the feasibility and technical value of the present invention, a complete implementation path and performance prediction scheme specifically designed based on the core calculation results of the present invention (Mo-Mo dual-vacancy stability, asymmetric adsorption mechanism, and low-barrier diffusion channels) is provided below. This scheme clarifies the entire process logic from theoretical target to material preparation and performance verification, demonstrating the clear guiding role of the present invention in experimental research and development.

[0094] Example: Preparation and electrochemical performance verification of 2D MoB containing Mo-Mo double vacancy defects as a lithium-ion battery anode.

[0095] (1) Design of targeted material preparation pathway

[0096] Precursor processing: Using bulk MoAlB as a precursor, the Al layer is selectively etched away using a wet chemical method (e.g., NaOH solution) to obtain multilayer 2D MoB nanosheets. This step provides the basic material for subsequent defect engineering.

[0097] Defect engineering is introduced: Based on the most stable defect target (Mo-Mo double vacancy, with the lowest formation energy of only 0.41 eV) identified in this invention, a process path combining ion irradiation and subsequent annealing is designed. By controlling the process parameters, controllable point defects can be introduced into the MoB layer; subsequently, through annealing, the thermodynamic stability of the Mo-Mo double vacancy is utilized to promote its formation, migration, and stabilization. This step directly applies the key findings of this invention, achieving a precise transformation from "calculated target" to "process objective."

[0098] Material characterization: The prepared material was characterized using high-resolution transmission electron microscopy (HRTEM) and electron energy loss spectroscopy (EELS) to reveal its 2D layered structure and detect local atomic vacancies; X-ray photoelectron spectroscopy (XPS) was used to analyze changes in the chemical states of surface elements. These characterization techniques can be used to verify whether Mo-Mo double-vacancy defects have been successfully introduced.

[0099] (2) Electrode fabrication and battery assembly

[0100] This section follows the standard procedures for research on electrochemical energy storage materials to ensure the reproducibility of the approach:

[0101] Electrode slurry preparation: The above-treated defective 2D MoB material, conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) binder are thoroughly mixed and ground in a mass ratio of 8:1:1 to form a uniform slurry.

[0102] Electrode preparation: The prepared uniform slurry was uniformly coated onto a copper foil current collector. It was then dried in a 60°C vacuum oven for 12 hours to completely remove the solvent. Subsequently, the electrode was pressed to improve electrode density and mechanical integrity. Finally, it was punched into a 14 mm diameter disc to serve as the working electrode.

[0103] Button cell assembly: In a glove box filled with argon and with a water and oxygen content of less than 0.1 ppm, a standard CR2032 button cell was assembled using a lithium metal sheet as the counter electrode and reference electrode, a Celgard 2400 porous polyolefin membrane as the separator, and a 1M LiPF6 solution dissolved in ethylene carbonate (EC) / dimethyl carbonate (DMC) (volume ratio 1:1).

[0104] (3) Focus of performance prediction and analysis based on calculation results

[0105] The calculation results of this invention not only predict material properties, but also indicate the key points and analytical focus for subsequent experimental verification:

[0106] High-rate performance prediction and verification focus: Since calculations have confirmed the existence of an ultra-low diffusion barrier channel (0.410 eV) on the lower surface, it can be predicted that electrodes fabricated along this path will exhibit superior capacity retention compared to perfect lattice MoB in high current density (e.g., 0.5, 1.0, 2.0 A / g) charge-discharge tests. Experimental rate performance data will directly verify the effectiveness of this low-barrier channel for rapid ion transport.

[0107] High-capacity characteristic prediction and verification focus: Calculations revealed that the vacancy centers on the upper surface are strong adsorption sites (adsorption energy -1.453 eV), predicting that this material will provide higher lithium-ion storage active sites, and its reversible specific capacity potential is expected to significantly surpass that of graphite anodes (372 mAh / g). The discharge plateau and reversible capacity in constant current charge-discharge tests will be key verification indicators.

[0108] Structural stability and cycle life prediction: Since the Mo-Mo double vacancy configuration has the lowest formation energy and AIMD simulations have shown that it is kinetically stable at 300K, it can be inferred that the electrode constructed in this way will have better structural integrity and a slower capacity decay trend in long-term cycling tests.

[0109] The focus of the verification of conductivity and interface dynamics: Calculation results show that the material maintains a metallic electronic structure. Figure 5 Therefore, electrochemical impedance spectroscopy (EIS) testing should focus on the high-frequency semicircle (charge transfer impedance), which is expected to be small and grow slowly. This is consistent with the prediction of high electronic conductivity and is conducive to maintaining rapid electrode reaction kinetics.

[0110] (4) Summary of the plan

[0111] This implementation path and performance prediction scheme clearly demonstrates how to transform the theoretical findings of this invention (the most stable defect target, induced asymmetric adsorption, and well-defined fast ion channels) into a specific, operable, and targeted material preparation and performance research scheme. All performance predictions are derived from rigorous calculations, ensuring that subsequent experimental verification work is targeted and effective. This fully demonstrates that this invention is not merely a theoretical innovation, but a key tool connecting material computational design and experimental research and development, guiding the targeted development of high-performance electrode materials, and possesses extremely high technical guidance value and promising industrial application prospects.

[0112] To fully demonstrate the technical effects of this invention, the following systematic evidence is provided, combining specific calculation data, simulation results charts, and comparisons with existing technologies. This evidence, ranging from defect stability and electronic structure to core electrochemical performance, forms a complete and mutually corroborating chain of evidence, conclusively confirming the inventiveness of this invention and its unexpected technical effects.

[0113] (a) Key evidence confirming that the Mo-Mo double vacancy is the most stable intrinsic defect

[0114] This set of evidence directly supports claims 1-2, demonstrating that the defect targets identified in this invention have clear thermodynamic and kinetic advantages.

[0115] Forming quantitative evidence (Table 1 and) Figure 3 By systematically comparing the formation energies of ten different dual-vacancy configurations across three categories, the data (Table 1) clearly shows that the formation energies of all Mo-Mo dual vacancies (0.41–1.22 eV) are significantly and systematically lower than those of BB dual vacancies (1.97–2.51 eV) and Mo-B dual vacancies (1.22–2.10 eV). Among them, the "Mo-Mo-1" configuration has the lowest energy (0.41 eV). Figure 3 The bar chart visually illustrates this huge difference, irrefutably proving that the Mo-Mo double vacancy is the most thermodynamically stable intrinsic double vacancy type in 2D MoB, providing a unique and clear theoretical target for the experimentally oriented introduction of this defect.

[0116] Evidence of dynamic stability ( Figure 4 AIMD simulations (300 K, 5 ps) on the most stable "Mo-Mo-1" configuration showed that the system temperature fluctuated smoothly without structural reconstruction or collapse. This demonstrates that the defect exhibits good kinetic stability at battery operating temperatures, is non-metastable, and can exist stably in practical applications.

[0117] Binding energy evidence (Table 2): The calculated binding energy of the "Mo-Mo-1" double vacancy is consistently positive (approximately +0.456 eV), indicating a weak repulsion between the two Mo single vacancies, thermodynamically inclined to disperse. This energy explains why the double vacancy is more likely to form directly as an intrinsic defect rather than from the aggregation of single vacancies, further supporting the conclusion that it is a stable, dominant defect.

[0118] (ii) Evidence confirming that the material maintains the electronic structure required for high-performance electrodes

[0119] This evidence supports claim 3, demonstrating that the defect introduces an intrinsic conductivity that does not impair the material.

[0120] Evidence of electronic density of states ( Figure 5 ): Electronic density of states diagram of 2D MoB containing Mo-Mo double vacancies ( Figure 5 The results show that the Fermi level has a non-zero density of states and a continuous range of electronic states, primarily contributed by Mo-d orbitals. This directly proves that the material retains its metallicity, and that introducing specific defects did not open the band gap. High electronic conductivity is fundamental for electrodes to achieve rapid charge transfer and obtain excellent rate performance.

[0121] (III) Core evidence confirming "defect-induced surface asymmetry" and adsorption differentiation

[0122] This set of evidence supports claims 1 and 4, revealing the novel physical mechanism discovered in this invention.

[0123] Quantitative evidence of adsorption energy (Table 3): Systematic calculation of lithium ion adsorption energy at different sites. Key data show: upper surface vacancy center (V Mo-top The adsorption energy is -1.453 eV, while the top site of the B atom on the lower surface (T) B-bottom The adsorption energy is -0.622 eV, with a difference as high as 0.83 eV. This provides conclusive data to quantitatively demonstrate that the Mo-Mo dual vacancies actively disrupt the surface chemical homogeneity, inducing functional partitioning of a "strong adsorption region on the upper surface" and a "moderate adsorption region on the lower surface".

[0124] Visual evidence of adsorption configuration ( Figure 6 ): Figure 6 The atomic structure diagram visually demonstrates the stable configuration of lithium ions at the vacancy centers (strong adsorption) on the upper surface and the top sites of B atoms (moderate adsorption) on the lower surface, transforming abstract energy data into visual evidence of atomic arrangement and enhancing its persuasiveness.

[0125] (iv) Decisive evidence confirming diffusion anisotropy and fast ion channels

[0126] This set of evidence is the core of proving the invention’s potential to achieve “fast charge and discharge” (claims 4-6), and also the most creative manifestation of its effect.

[0127] Quantitative and Visual Evidence of Diffusion Barrier Figure 7 ): Calculate the energy barrier of critical migration paths using the CI-NEB method. Figure 7 The energy barrier curves provide quantitative evidence: lithium ions need to overcome a high energy barrier of 0.833 eV to diffuse between vacancies on the upper surface, while diffusion between B atoms on the lower surface only requires a low energy barrier of 0.410 eV. The contrast between the two curves is immediately apparent, directly and visually demonstrating the significant anisotropy of lithium ion diffusion determined by the defect structure.

[0128] Evidence for quantitative structure-activity relationship of "adsorption-diffusion" ( Figure 8 ): Figure 8 Adsorption energy (E) ads ) and diffusion barrier (E barrier The correlation plot clearly shows a linear positive correlation trend: "the stronger the adsorption (the larger the negative value), the higher the diffusion barrier." This plot not only quantitatively correlates thermodynamics (adsorption) and kinetics (diffusion), but also elucidates the root cause of performance regulation from a physical mechanism perspective: a moderate adsorption strength (-0.622 eV) precisely balances storage capacity and migration resistance, thus forming a low-barrier fast channel of 0.410 eV. The establishment of this quantitative law is the key innovation of this invention.

[0129] (V) Comprehensive Analysis of the Comparison Effect with the Comparative Example (Perfect Lattice 2D MoB)

[0130] To highlight the unexpected technical effects of this invention, the performance of the material of this invention is compared with that of the theoretically perfect lattice 2DMoB (comparative example):

[0131]

[0132] Example 1: Construction and stability confirmation of a double-vacancy defect configuration

[0133] Model Construction and Optimization: In this embodiment, Material Studio software was used for modeling to obtain the MoB orthorhombic crystal system. The corresponding precursor parent phase MoAlB was obtained from the Materials Project crystal structure database to obtain MoB. The corresponding monolayer was obtained using the Cleave Surface function, and then a 3×3×1 perfect supercell MoB model was obtained using Supercell. By setting appropriate parameters in the CASTEP module, the BFGS algorithm was used to perform complete structural relaxation on the supercell to obtain a stable structural model. Then, relevant characteristic parameters were calculated, where the lattice parameters and angles were a=3.113 Å, b=3.228 Å, and θ=90°, respectively.

[0134] Based on this, two adjacent molybdenum atoms were removed from the perfect crystal structure to form an initial double-vacancy defect structure. Simultaneously, multiple double-vacancy structures with different relative positions were constructed as controls, as detailed in Table 1. All defect models underwent thorough geometric optimization until the aforementioned convergence criteria were met.

[0135] Formation energy and binding energy calculation: Defect formation energy (E form Calculate using the following formula:

[0136] E form =E defect -E perfect +n×μ

[0137] Among them, E defect and E perfect , respectively, represent the total energy of the defective supercell and the perfect supercell; n is the number of atoms removed; μ is the chemical potential of the corresponding atom. For the chemical formula of a single atom, it is calculated based on the most stable bulk phases (bcc-Mo and α-B), which is consistent with the above calculation process, except that it is converted into a single cell for optimization during the calculation process to obtain the chemical potential of a single atom.

[0138] Results and Analysis: Table 1 lists the calculated formation energies of all double-vacancy configurations. The results show that the formation energies of Mo-Mo double vacancies (0.41 eV–1.22 eV) are generally and significantly lower than those of BB double vacancies (1.97 eV–2.51 eV) and Mo-B double vacancies (1.22 eV–2.10 eV). Among these, the "Mo-Mo-1" configuration has the lowest formation energy (0.41 eV). This result demonstrates that Mo-Mo double-vacancy defects can exist as intrinsically stable defects in 2D MoB materials, providing a stable structural basis for subsequent interfacial modulation and ion transport studies.

[0139] Furthermore, to investigate the relationship between two-vacancy and single-vacancy configurations, the binding energy (E) of the most stable two-vacancy configuration (Mo-Mo-1) was calculated. bind ):

[0140] E bind =E DV +E perfect -E SV1 -E SV2

[0141] Among them, E DV For the total energy of two vacant sites, E SV1 and E SV2 The energy of the single-vacancy model created at the corresponding positions of the two vacancy sites in the same supercell.

[0142] Further calculations show that the binding energies calculated for the three different cases are highly consistent, all around +0.456 eV, as shown in Table 2. This consistently positive value has a clear physical meaning: regardless of the specific local environment of the two initial Mo monovacancies, merging them to form a "Mo-Mo-1" double vacancy is a process that requires energy absorption (approximately 0.456 eV). This quantitatively and strongly confirms that there is a weak thermodynamic repulsion between the two Mo monovacancies in 2D MoB, and they tend to exist in a dispersed manner. This finding implies that the Mo-Mo double vacancy observed in experiments is more likely to be generated directly during material preparation or processing, rather than formed by the migration and aggregation of two free monovacancies.

[0143] Table 1. Formation energy of various double-vacancy defects in 2D MoB

[0144]

[0145] Table 2. Calculation of binding energy of “Mo-Mo-1” double vacancy and analysis of single vacancy interactions

[0146]

[0147] Example 2: Verification of the electronic structure characteristics of double-vacancy electrode materials

[0148] To confirm whether 2D MoB containing Mo-Mo double vacancies retains the high electronic conductivity necessary for its use as an electrode material, this invention calculated its density of electronic states (DOS). The results are as follows: Figure 5 As shown, a non-zero, continuous electronic density of states exists near the Fermi level (energy zero), primarily contributed by Mo-d orbital electrons. This characteristic clearly confirms that the defective material retains its metallic electronic structure and has not opened its band gap to become semiconductor due to the introduction of double vacancies. Excellent electronic conductivity is fundamental to achieving fast charge transfer and good rate performance. This, combined with the fast ion diffusion channels to be revealed later, constitutes the dual advantages of this material as a high-performance electrode.

[0149] Example 3: Calculation of Lithium Ion Adsorption Performance and Verification of Surface Site Differentiation

[0150] In this embodiment, based on the stable double-vacancy structure obtained in Example 1, the local atomic environment of its upper and lower surfaces is analyzed, and lithium ions are introduced above different surface atoms to search for adsorption configurations. Initial adsorption positions are set at the center of the double vacancy, the top of the molybdenum atom, and the top of the boron atom, respectively, and relaxation optimization is performed on all adsorption structures to calculate the adsorption intensity of lithium ions at different positions.

[0151] Adsorption model construction: Based on the optimized "Mo-Mo-1" dual-vacancy model, possible adsorption sites of Li atoms were systematically explored on its upper and lower surfaces, mainly including: vacancy centers (V on the upper surface) Mo-top ), Mo atom top position (T Mo-top ), B atom top position (T B-top ), bottom Mo atom top site (T) Mo’-top ), bottom B atom top site (T) B’-top ); directly below the center of the empty space on the lower surface (V Mo-bottom ), Mo atom top position (T Mo-bottom ), B atom top position (T B-bottom ), bottom Mo atomic sites (T Mo’-bottom ), bottom B atom site (T B’-bottom An initial adsorption model was constructed by placing a Li atom approximately 1.5 Å above each candidate site.

[0152] Adsorption energy calculation: Structural optimization was performed on all adsorption models. Adsorption energy of lithium ions (E) ads Calculate using the following formula:

[0153] E ads =E system+Li -E system -E Li

[0154] Among them, E system+Li It is the total energy of the lithium-containing adsorption system, E system It is the total energy of the "Mo-Mo-1" dual-vacancy foundation, E Li It is the energy of a single lithium atom (taken from the total energy of a body-centered cubic lithium crystal unit cell divided by the number of atoms in the unit cell).

[0155] Results and Analysis: Table 3 lists the calculated adsorption energies of the main adsorption sites. The data shows the adsorption energies of the upper surface vacancy centers (V0). Mo-top The site exhibits the strongest lithium-ion adsorption, with an adsorption energy as low as -1.453 eV, indicating a very deep energy trap. The top B atom site on the lower surface (T...) B-bottom The adsorption site at () is of moderate strength, with an adsorption energy of -0.622 eV. The adsorption energies of other sites fall between these values ​​or are weaker. This result clearly confirms a core finding of this invention: the existence of Mo-Mo dual-vacancy defects disrupts the chemical homogeneity of the 2D MoB surface, inducing the formation of adsorption sites on the upper and lower surfaces with drastically different adsorption properties—that is, strong adsorption sites on the upper surface coexist with moderate adsorption sites on the lower surface. This asymmetry provides a physical basis for the subsequent construction of ion migration channels with different diffusion resistances.

[0156] Table 3. Adsorption energies of lithium ions on Mo-Mo dual-vacancy MoB sites

[0157]

[0158] Example 4: Ion Diffusion Kinetics and Anisotropy Analysis

[0159] In this embodiment, the stable adsorption configuration obtained in Example 3 was selected as the initial and final states to simulate the diffusion behavior of lithium ions along different surface migration paths. By constructing multiple migration path models between adjacent adsorption sites, the energy changes required for lithium ions to migrate from strongly adsorbed regions to neighboring sites and to migrate in moderately adsorbed regions were calculated.

[0160] Diffusion path setup: Based on two characteristic adsorption sites selected in Example 2 (strong adsorption site V on the upper surface) Mo-top Suitable adsorption sites T on the lower surface B-bottom Each of them designed its most representative diffusion path.

[0161] Upper surface path: Starting from the vacancy center site as the initial state (IS), the migration to the adjacent upper surface Mo vacancy center site is the final state (FS).

[0162] Lower surface path: The initial state is the top B atom site (IS), and the final state is the adjacent lower surface B atom site (FS).

[0163] Transition state search and energy barrier calculation: The climbing elastic band (CI-NEB) method is used to search for the transition states of the two paths described above. Multiple intermediate images are set for each path. After convergence, the image with the highest energy is extracted as the transition state (TS), and the diffusion energy barrier (E) is calculated using the following formula. barrier ):

[0164] E barrier =E TS -E IS

[0165] The calculation results of the diffusion barrier are as follows Figure 7 As shown, for the upper surface (diffusion from strong adsorption sites), the energy barrier for lithium-ion migration is as high as 0.833 eV; while for the lower surface (diffusion from adsorption sites), the energy barrier for lithium-ion migration is only 0.410 eV.

[0166] This indicates that the energy required to migrate from a strongly adsorbed region is significantly higher than that required to migrate from a moderately adsorbed region, suggesting that stronger adsorption corresponds to higher diffusion resistance, thus establishing a positive correlation between adsorption strength and diffusion resistance. This result validates the fundamental mechanism by which the ion migration kinetics can be indirectly controlled by modulating the local adsorption environment.

[0167] Example 5: Validation of Performance Prediction Process Based on Energy Correlation

[0168] In this embodiment, a correlation analysis is performed on the adsorption strength and diffusion resistance calculated under the optimal adsorption conditions to form a performance prediction model, thereby verifying the effectiveness of this method in judging the trend of ion migration performance.

[0169] like Figure 8 The observed pattern is that sites with stronger adsorption (-1.453 eV) have higher diffusion barriers (0.833 eV), while sites with moderate adsorption (-0.622 eV) have lower diffusion barriers (0.410 eV). This quantitatively reveals the microscopic kinetic mechanism by which strong adsorption leads to difficulties in ion desorption and migration. This also provides an efficient and widely applicable design method for defect engineering and performance regulation.

[0170] Based on this, the present invention explicitly points out that in 2D MoB containing Mo-Mo double vacancies, the lower surface (especially the B atom-related channels) is a preferred diffusion channel for rapid lithium-ion transport. This diffusion anisotropy determined by the intrinsic defect structure provides a novel approach and theoretical basis for designing new electrode materials with directional rapid ion transport capabilities.

[0171] The above description 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 two-dimensional molybdenum boride electrode material containing double vacancy defects, characterized in that, The electrode material contains intrinsic double-vacancy defects in its crystal lattice, consisting of two adjacent molybdenum atom vacancies. The dual-vacancy defects create asymmetric local coordination environments on the upper and lower surfaces of the material, resulting in a strong lithium-ion adsorption region on the upper surface and a moderate lithium-ion adsorption region on the lower surface. This creates a spatially separated ion potential energy distribution with varying adsorption strengths within the material. This potential energy distribution is used to simultaneously constrain the adsorption site of lithium ions and guide their migration along predetermined low-resistance channels, thereby achieving synergistic regulation of lithium ion adsorption behavior and diffusion path.

2. The two-dimensional molybdenum boride electrode material as described in claim 1, characterized in that, The double-vacancy defect has the lowest formation energy among all double-vacancy configurations, and its binding energy is positive, allowing the double-vacancy defect to exist in a stable separated state in the crystal lattice.

3. The two-dimensional molybdenum boride electrode material as described in claim 1, characterized in that, The presence of the double vacancy defect does not disrupt the metallic electronic structure of the two-dimensional molybdenum boride, allowing the material to maintain a continuous electronic state distribution near the Fermi level, thereby achieving directional control of ion transport while maintaining electronic conductivity.

4. A mechanism for regulating the lithium-ion diffusion potential gradient based on double-vacancy defects, characterized in that, By incorporating intrinsic double-vacancy defects consisting of two adjacent molybdenum atom vacancies in two-dimensional molybdenum boride materials, Adsorption regions with different adsorption strengths are formed on the upper and lower surfaces of the material. This results in high diffusion resistance for lithium ions in the strong adsorption region and low diffusion resistance in the moderate adsorption region. This creates an energy relationship between adsorption strength and diffusion resistance within the material, which guides lithium ions to preferentially migrate along regions with low diffusion resistance.

5. The regulatory mechanism as described in claim 4, characterized in that, The adsorption strength is positively correlated with the diffusion resistance, so that the region with lower adsorption energy corresponds to lower diffusion resistance, thereby forming a preferred migration channel for lithium ions.

6. The regulatory mechanism as described in claim 4, characterized in that, The preferred migration channel is located on the lower surface of the double-vacancy defect and is formed by a continuous in-plane migration path of boron atom top sites, which is used to realize the rapid in-plane transport of lithium ions.

7. A method for predicting and regulating lithium-ion transport performance based on the regulation mechanism described in any one of claims 4 to 6, characterized in that, Includes the following steps: A two-dimensional molybdenum boride structural model containing double-vacancy defects was constructed; Determine the stable adsorption configuration of lithium ions on the upper and lower surfaces of the model and obtain the corresponding adsorption strength; Calculate the diffusion resistance that lithium ions need to overcome to migrate between different adsorption configurations; The adsorption strength and diffusion resistance were correlated to identify preferred migration channels with low diffusion resistance and to guide the control of material structure.

8. The method as described in claim 7, characterized in that, By comparing the diffusion resistance corresponding to different surface orientations or different migration paths, the anisotropic diffusion behavior of lithium ions in two-dimensional molybdenum boride materials is quantitatively revealed.

9. The method as described in claim 7, characterized in that, A vacuum isolation layer is set in a direction perpendicular to the material plane to eliminate the mutual influence between periodic structures.

10. The method as described in claim 7, characterized in that, The structural model containing the double vacancy defect was subjected to finite temperature dynamic stability verification to confirm that the double vacancy defect maintains structural stability within the operating temperature range.

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