CN-122025630-A - 2D MoB electrode material containing double vacancy defects and performance regulation and control method thereof

CN122025630ACN 122025630 ACN122025630 ACN 122025630ACN-122025630-A

Abstract

The invention belongs to the field of electrochemical energy storage and material calculation design, and discloses a 2D MoB electrode material containing double vacancy defects and a performance regulation method thereof, wherein the electrode material is internally provided with a Mo-Mo double vacancy defect structure with the most stable thermodynamics. The defect induces asymmetric chemical environment on the upper and lower surfaces of the material, wherein the center of the vacancy on the upper surface is a strong adsorption site, and the top of the B atom on the lower surface is a medium adsorption site. This adsorption differential directly results in significant anisotropy of lithium ion diffusion, with the diffusion energy barrier of the lower surface channel (about 0.410 eV) being much lower than the upper surface (about 0.833 eV), the preferred path for rapid ion transport. The invention also provides a performance prediction method based on the first sexual principle, which establishes a quantitative association rule of strong adsorption-high diffusion energy barrier by systematically screening defect configuration, calculating adsorption energy and diffusion energy barrier, and provides clear theoretical guidance and design tools for designing high-performance two-dimensional electrode materials through rational defect engineering.

Inventors

LU XUEFENG
ZHANG WENBO
GUO XIN
REN JUNQIANG
XUE HONGTAO
TANG XINGCHANG

Assignees

兰州理工大学

Dates

Publication Date: 20260512
Application Date: 20260120

Claims (10)

1. A two-dimensional molybdenum boride electrode material containing double vacancy defects is characterized in that, The electrode material has an intrinsic double vacancy defect in the crystal lattice consisting of two adjacent molybdenum atom vacancies, The double vacancy defects form an asymmetric local coordination environment on the upper surface and the lower surface of the material, so that the upper surface of the material forms a lithium ion strong adsorption area, the lower surface of the material forms a lithium ion medium adsorption area, Thereby constructing ion potential energy distribution with different adsorption strength and space separation in the material, The potential energy distribution is used for simultaneously restraining the adsorption position of the lithium ions and guiding the lithium ions to migrate along a preset low-resistance channel, so that the cooperative regulation and control of the adsorption behavior and the diffusion path of the lithium ions are realized.
2. The two-dimensional molybdenum boride electrode material of claim 1, The double vacancy defects have the lowest formation energy among all the double vacancy configurations and the binding energy thereof is positive, so that the double vacancy defects exist in a stable separated state in the crystal lattice.
3. The two-dimensional molybdenum boride electrode material of claim 1, The existence of the double vacancy defects does not destroy the metallic electronic structure of the two-dimensional molybdenum boride, so that the material keeps continuous electronic state distribution near the Fermi energy level, and the directional regulation and control of ion transport are realized while the electronic conductivity is maintained.
4. A regulation and control mechanism for constructing a lithium ion diffusion potential energy gradient based on double vacancy defects is characterized in that, By providing an intrinsic double vacancy defect consisting of two adjacent molybdenum atom vacancies in a two-dimensional molybdenum boride material, Forming adsorption areas with different adsorption intensities on the upper and lower surfaces of the material, The lithium ion is enabled to correspond to high diffusion resistance in a strong adsorption area and low diffusion resistance in a medium adsorption area, Thereby forming an energy relationship within the material where the adsorption strength and diffusion resistance cooperatively couple to guide the preferential migration of lithium ions along the low diffusion resistance region.
5. The regulatory mechanism of claim 4, wherein, The adsorption strength and the diffusion resistance are in positive correlation, so that the area with lower adsorption energy corresponds to the area with lower diffusion resistance, and a preferable migration channel of lithium ions is formed.
6. The regulatory mechanism of claim 4, wherein, The optimized migration channel is positioned on the lower surface of the double-vacancy defect, and a continuous in-plane migration path is formed by the top position of the boron atom and is used for realizing rapid in-plane transmission of lithium ions.
7. A method for predicting and controlling lithium ion transport performance based on the control mechanism according to any one of claims 4 to 6, comprising the steps of: constructing a two-dimensional molybdenum boride structural model containing double vacancy defects; Determining stable adsorption configuration of lithium ions on the upper and lower surfaces of the model and obtaining corresponding adsorption strength; Calculating the diffusion resistance which is needed to be overcome by the migration of lithium ions between different adsorption configurations; And carrying out correlation analysis on the adsorption strength and the diffusion resistance so as to identify a preferable migration channel with low diffusion resistance and guide material structure regulation.
8. The method of claim 7, wherein, By comparing diffusion resistances corresponding to different surface directions or different migration paths, the anisotropic diffusion behavior of lithium ions in the two-dimensional molybdenum boride material is quantitatively revealed.
9. The method of claim 7, wherein, A vacuum isolation layer is provided in a direction perpendicular to the plane of the material to eliminate interactions between the periodic structures.
10. The method of claim 7, wherein, And carrying out limited temperature dynamic stability verification on the structural model containing the double-vacancy defects so as to confirm that the double-vacancy defects keep stable in structure in the working temperature range.

Description

2D MoB electrode material containing double vacancy defects and performance regulation and control method thereof Technical Field The invention belongs to the technical field of electrochemical energy storage and material computing design, and particularly relates to a 2D MoB electrode material containing double vacancy defects and a performance regulation method thereof. Background With the rapid development of renewable energy transformation and electric automobile industry, energy storage devices with high energy density and high power density become the core of the advance of the push energy technology. Lithium ion batteries are currently the most predominant portable and electric car energy storage solutions, whose performance is highly dependent on the electrochemical properties of the electrode material, especially the theoretical capacity, ion adsorption capacity and ion diffusion kinetics of the negative electrode material. The energy density of batteries is limited by the relatively low theoretical capacity of the commonly commercialized graphite negative electrode, and therefore, development of a negative electrode material with higher theoretical capacity and efficient ion transport is a key technical task. In this field, two-dimensional materials are considered to be extremely potential electrode material platforms with their high specific surface area, tunable electronic structure, and potential open ion channel advantages. In particular, transition metal borides (MBenes) have attracted considerable attention in the energy storage world as new members of the two-dimensional family of materials, their unique electronic and structural properties. The prior researches show that MBenes serving as a layered two-dimensional material not only has excellent conductivity, but also can provide rich active sites, is favorable for the adsorption and migration of ions, and has wide application potential in the fields of metal ion batteries, electrocatalysis and the like. The theoretical properties of two-dimensional molybdenum boride are particularly attractive in the transition metal boride family. Related work has predicted from a theoretical perspective the potential advantages of two-dimensional borides like the M 2B2 structure (e.g., mo 2B2) in battery applications, including higher theoretical specific capacities and low diffusion energy barriers, whose minimum lithium ion diffusion energy barriers were calculated to be comparable to or even better than graphite and partial MXene systems. However, the prior publications mainly stay in the prediction of macroscopic properties of perfect lattice materials, and in-depth analysis of lithium ion diffusion mechanisms of the perfect lattice materials is still preliminary, and especially the regular understanding of the properties of materials under defect regulation is lacking. In addition, in MBenes's research, theoretical research has demonstrated its potential to regulate electronic structure and enhance active sites, but its ion adsorption behavior as an electrode material, the effect of defects on diffusion kinetics, and the association with diffusion channels have not yet formed systematic knowledge, as compared to two-dimensional material systems such as MXene. Against this background, the prior art suffers from a critical disadvantage. On one hand, the defect design of the two-dimensional molybdenum boride material is still in the primary stage, quantitative comparison of various defect configurations on lithium ion adsorption and migration behaviors is hardly related in the prior published data, and on the other hand, the closed-loop correlation of the defect configuration-ion adsorption energy-diffusion energy barrier of the material is constructed, so that a designer can reasonably predict and directionally optimize the electrochemical performance of the material on an atomic scale, and related work is not yet reported in a system at present. In addition, the prior art has little in-depth research and discussion on thermodynamic stability, electronic structure change and specific influence of the two-vacancy defects in the two-dimensional molybdenum boride on ion transmission dynamics, which directly results in lack of an operable design strategy and structure-activity mechanism in the process of developing a high-performance energy storage electrode material, thereby preventing further application development of the two-dimensional molybdenum boride in the field of high-performance lithium ion battery cathodes. In summary, the prior art has not provided a framework and systematic knowledge for quantitatively analyzing the influence of a two-dimensional molybdenum boride defect structure on the adsorption and diffusion behaviors of lithium ions, which is a technical problem to be solved in the current high-performance energy storage material design and optimization. Disclosure of Invention Aiming at the problems existing in the prior art, the inv