A defect-rich rock-salt high-entropy oxide battery material, preparation method and application thereof

Abstract

The application belongs to the technical field of new energy materials, and particularly relates to a defect-rich rock-salt high-entropy oxide battery material and a preparation method and application thereof. The chemical formula of the material is (LiCoCuMgZnM)O, wherein M is at least one of Mn and Fe. In order to improve the electrochemical performance of the material, the amount of fuel glycine is precisely controlled through element regulation, and a new rock-salt high-entropy oxide battery material rich in oxygen vacancies and moderate lattice distortion is quickly prepared under an oxygen-poor condition. Finally, the excellent electrochemical energy storage performance of the electrode material under high rate is realized. The defect-rich new rock-salt high-entropy oxide battery material provided by the application is used as a lithium ion battery negative electrode material, and remarkable improvement is achieved in the rate performance. The preparation method of the material has a simple process and mild reaction conditions, and has wide applicability, and can be used to regulate the defects of high-entropy oxides with other crystal structures and chemical compositions.

Description

A defect-rich rock-salt type high-entropy oxide battery material, its preparation method, and its application. Technical Field

[0001] This invention belongs to the field of new energy materials technology, specifically relating to a defect-rich rock-salt type high-entropy oxide battery material, its preparation method, and its application. Background Technology

[0002] Rock salt type (Co) 0.2 Cu 0.2 Mg 0.2 Ni 0.2 Zn 0.2 High-entropy oxides (HEOs), with their unique structural characteristics and excellent performance, have shown great application potential in energy storage, catalysis, and electronic devices. Compared with traditional single oxides, the high-entropy effect of employing five or more metal elements endows them with superior structural stability and chemical activity. In catalysis, HEOs are widely used in oxygen reduction, nitrogen reduction, and oxygen evolution reactions through metal synergistic effects. In energy storage, HEOs not only possess excellent electrical conductivity and thermal stability but also alleviate the volume expansion problem during battery charging and discharging, and improve capacity and cycle stability. Furthermore, abundant oxygen vacancies promote the efficient diffusion of lithium and sodium ions. With further research, this material is expected to play an even more important role in future energy, environmental protection, and catalysis fields.

[0003] In 2015, Rost first prepared rock-salt type (CoO+NiO+CoO with rock salt structure, CuO with chalcopyrite structure, and ZnO with wurtzite structure) using solid-state sintering method as raw materials. 0.2 Cu 0.2 Mg 0.2 Ni 0.2 Zn 0.2 O high-entropy oxides. Due to the variable valence states of transition metal cations, currently, besides (Co) 0.2 Cu 0.2 Mg 0.2 Ni 0.2 Zn 0.2 In addition to O, another rock-salt type high-entropy oxide (LiCoCuMgNiZn)O was also reported (Liu XF, Xing YY, Xu K, et al. Kinetically Accelerated Lithium Storage in High-Entropy (LiMgCoNiCuZn)O Enabled By Oxygen Vacancies. Small 2022, 18(18):2200524.). For rock-salt type high-entropy oxides (Co... 0.2 Cu 0.2Mg 0.2 Ni 0.2 Zn 0.2 )O elemental regulation to introduce inactive low-valence Li + Morphology modulation (Liu X, Wang H, Dong L, et al. Molten salt synthesis, morphology modulation, and lithiation mechanism of high entropy oxide for robust lithium storage. Journal of Energy Chemistry 2023, 86: 536-545.) or polyaniline coating (Yen JZ, Yang YC, Tuan HY. Interface engineering of high entropy Oxide@Polyaniline heterojunction enables highly stable and excellent lithium ion storage performance. Chemical Engineering Journal, 2022, 450: 137924.) has improved its electrochemical performance to some extent.

[0004] However, there are currently no research reports on optimizing the electrochemical performance of rock salt oxides by regulating the active transition metal elements. Summary of the Invention

[0005] The purpose of this invention is to solve the problems of existing rock salt type (Co) 0.2 Cu 0.2 Mg 0.2 Ni 0.2 Zn 0.2 To address the issue that high-entropy oxides (HNO) have a single chemical composition, which limits their electrochemical performance, this paper proposes a defect-rich rock-salt type HNO battery material, its preparation method, and its applications. On one hand, by selecting Li and Fe elements or Li and Mn elements with similar cation radii and significant differences in valence to replace the original metal components, a single rock-salt type HNO is successfully prepared. On the other hand, by controlling the amount of fuel used, a novel rock-salt type HNO is rapidly prepared under oxygen-deficient conditions, rich in oxygen vacancies and with appropriate lattice distortion, thereby achieving high-rate electrochemical energy storage.

[0006] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution:

[0007] This invention provides a defect-rich rock-salt type high-entropy oxide battery material with the chemical formula (LiCoCuMgZnM)O, wherein M is at least one of Mn and Fe.

[0008] This invention also provides a method for preparing a defect-rich rock-salt type high-entropy oxide battery material, comprising the following steps:

[0009] 1) Weigh the metal salts according to the chemical formula (LiCoCuMgZnMnM)O, dissolve them in distilled water, stir well, and obtain a mixed solution of metal salts.

[0010] 2) Weigh a certain amount of glycine as fuel, add it to the mixed solution of metal salts obtained in step 1), stir evenly at room temperature, place it in an oven to evaporate the water, and obtain a mixed gel.

[0011] 3) Place the mixed gel obtained in step 2) in a transparent electric furnace and react at 850-900℃ for 2-10 min to obtain a defect-rich rock salt type high-entropy oxide battery material.

[0012] Further, in step 1), the metal salt is a metal nitrate or a mixture of a metal nitrate and a metal chloride.

[0013] Furthermore, in step 2), the temperature of the oven is controlled at 80–100°C.

[0014] Further, in step 2), the molar ratio of the fuel to the total metal cations in the metal salt is 0.4 to 1.1:1.

[0015] The present invention also provides an application of a defect-rich rock-salt type high-entropy oxide battery material in the preparation of a secondary battery anode material.

[0016] The beneficial effects of this invention are:

[0017] 1. By using liquid-phase batching methods, we ensure that all raw materials are uniformly mixed at the molecular scale, thereby enabling the final product to achieve a precise stoichiometric ratio.

[0018] 2. By selecting Li and Fe elements with similar cation radii and significant differences in valence, as well as Li and Mn elements, novel rock salt-type high-entropy oxides were successfully prepared.

[0019] 3. Using glycine as fuel, rock salt-type high-entropy oxides rich in oxygen vacancies and with appropriate lattice distortion are synthesized rapidly under oxygen-deficient conditions by controlling the amount of fuel used.

[0020] 4. The defect-rich rock salt-type high-entropy oxide designed in this invention is not only suitable for energy storage, but also has application potential in multiple fields such as catalysis.

[0021] Of course, any product implementing this invention does not necessarily need to achieve all of the above advantages at the same time. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 shows the XRD pattern of the defect-rich rock salt type (LiCoCuMgZnMn)O high-entropy oxide powder prepared in Example 1;

[0024] Figure 2 is a SEM image of the defect-rich rock salt type (LiCoCuMgZnMn)O high-entropy oxide powder prepared in Example 1;

[0025] Figure 3 is a schematic diagram of the cycling performance and coulombic efficiency of the defect-rich rock salt type (LiCoCuMgZnMn)O high-entropy oxide powder prepared in Example 1.

[0026] Figure 4 shows the XRD pattern of the defect-rich rock salt type (LiCoCuMgZnFe)O high-entropy oxide powder prepared in Example 2. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] This invention uses metal nitrates or partially metal chlorides as the metal source and glycine as fuel. By controlling the amount of fuel used, a novel rock-salt type high-entropy oxide battery material rich in oxygen vacancies and with appropriate lattice distortion is synthesized rapidly under oxygen-deficient conditions.

[0029] Specific embodiments of the present invention are as follows:

[0030] Example 1

[0031] Preparation of rock salt type (LiCoCuMgZnMn)O high entropy oxide:

[0032] According to the chemical formula, the corresponding metal nitrates were weighed in equimolar ratios, specifically: 0.05 mol of LiNO3, Co(NO3)2·6H2O, Cu(NO3)2·3H2O, Mg(NO3)3·6H2O, Zn(NO3)2·6H2O, and Mn(NO3)2·4H2O were weighed, dissolved in 20 mL of distilled water, and stirred evenly at room temperature to obtain a mixed solution containing metal nitrates; then 0.17 mol of glycine was added to the above metal salt mixed solution, stirred evenly, and dried at 80 °C to obtain a gel; finally, the gel was reacted in a transparent electric furnace at 900 °C for 2 min to obtain a novel rock salt type (LiCoCuMgZnMn)O high-entropy oxide battery active material rich in oxygen vacancies and with appropriate lattice distortion.

[0033] The XRD and SEM images of the powder material are shown in Figures 1 and 2. The XRD pattern (Figure 1) shows that the prepared (LiCoCuMgZnMn)O high-entropy oxide battery active material has a single rock salt structure, and I (111) / I (200) =0.59 (theoretical value is 0.67), confirming that the prepared rock salt type high-entropy oxide has an appropriate amount of lattice distortion. SEM (Figure 2) shows that the prepared high-entropy oxide has a porous structure.

[0034] Fabrication of working electrodes and assembly of lithium-ion batteries:

[0035] The sample prepared above was used as the active material, Super P carbon black as the conductive agent, and polyvinylidene fluoride (PVDF) as the binder. These were mixed in a mass ratio of 7:2:1 and dissolved in N-methylpyrrolidone to form a slurry. The slurry was then uniformly coated onto a clean copper foil surface, cut, and used to form a working electrode with a diameter of 15.6 mm. Finally, pure lithium foil was used as the negative electrode, a polypropylene porous membrane as the separator, and a 1 mol / L LiPF6 solution of DMC-EC-DEC (volume ratio 1:1:1) as the electrolyte. All operations were performed in a glove box, and the resulting CR2025 coin cell was assembled.

[0036] The charge-discharge experiment of the battery was conducted on the Newway battery testing system and compared with that of (Co) batteries prepared under the same experimental conditions. 0.2 Cu 0.2 Mg 0.2 Ni 0.2 Zn 0.2 The electrochemical performance of the (LiCoCuMgZnMn)O electrode was compared, and the results are shown in Figure 3: The (LiCoCuMgZnMn)O electrode underwent charge-discharge cycle testing at a current density of 200 mA / g, and within the voltage range of 0.01–3.0 V, the specific capacity after 350 cycles was 550 mAh / g; (Co… 0.2 Cu 0.2 Mg0.2 Ni 0.2 Zn 0.2 The specific capacity of the O electrode under the same test conditions was 344 mAh / g. The results indicate that the specific capacity was improved by 59.9% through the synergistic effect of elemental substitution and defects.

[0037] Example 2

[0038] Preparation of rock salt type (LiCoCuMgZnFe)O high-entropy oxide:

[0039] According to the chemical formula, the corresponding metal nitrates were weighed in equimolar ratios, specifically: 0.05 mol of LiNO3, Co(NO3)2·6H2O, Cu(NO3)2·3H2O, Mg(NO3)3·6H2O, Zn(NO3)2·6H2O, and Fe(NO3)3·9H2O were weighed, dissolved in 20 mL of distilled water, and stirred evenly at room temperature to obtain a mixed solution containing metal nitrates; then 0.17 mol of glycine was added to the above metal salt mixed solution, stirred evenly, and dried at 80 °C to obtain a gel; finally, the gel was reacted in a transparent electric furnace at 900 °C for 2 min to obtain a novel rock salt type (LiCoCuMgZnMn)O high-entropy oxide battery active material rich in oxygen vacancies and with appropriate lattice distortion.

[0040] The XRD pattern of the powder material is shown in Figure 4, indicating that the prepared (LiCoCuMgZnFe)O high-entropy oxide has a single rock salt structure, and I (111) / I (200) =0.55 (theoretical value is 0.67) confirms that the lattice distortion of the prepared rock salt type high entropy oxide is appropriate.

[0041] Example 3

[0042] Preparation of rock salt type (LiCoCuMgZnFe)O high-entropy oxide:

[0043] According to the chemical formula, the corresponding metal nitrates were weighed in equimolar ratios, specifically: 0.05 mol of LiNO3, Co(NO3)2·6H2O, Cu(NO3)2·3H2O, Mg(NO3)3·6H2O, Zn(NO3)2·6H2O, and Fe(NO3)3·9H2O were weighed, dissolved in 20 mL of distilled water, and stirred evenly at room temperature to obtain a mixed solution containing metal nitrates; then 0.28 mol of glycine was added to the above metal salt mixed solution, stirred evenly, and dried at 80 °C to obtain a gel; finally, the gel was reacted in a transparent electric furnace at 900 °C for 5 min to obtain a novel rock salt type (LiCoCuMgZnFe)O high-entropy oxide battery active material rich in oxygen vacancies and with appropriate lattice distortion.

[0044] The chemical formula of the novel defect-rich rock-salt high-entropy oxide battery material of this invention is (LiCoCuMgZnM)O, where M is at least one of Mn and Fe. To improve the electrochemical performance of the material, this invention rapidly prepares a novel rock-salt high-entropy oxide battery material rich in oxygen vacancies and with moderate lattice distortion under oxygen-deficient conditions by elemental regulation and precise control of the amount of fuel glycine. Ultimately, excellent electrochemical energy storage performance of the electrode material at high rates is achieved. The novel defect-rich rock-salt high-entropy oxide battery material provided by this invention, as a negative electrode material for lithium-ion batteries, has achieved a significant improvement, especially in rate performance. The preparation method of this material is simple, the reaction conditions are mild, and it has wide applicability, and can be used to regulate defects in high-entropy oxides with other crystal structures and chemical compositions.

[0045] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a defect-rich rock-salt type high-entropy oxide battery material, characterized in that, The chemical formula of the material is (LiCoCuMgZnM)O, where M is at least one of Mn and Fe. The preparation method of the material includes the following steps: 1) Weigh the metal salt according to the chemical formula (LiCoCuMgZnM)O in stoichiometric ratio, dissolve it in distilled water, stir evenly to obtain a mixed solution of metal salt; the metal salt is a metal nitrate or a mixture of metal nitrate and metal chloride; 2) Weigh glycine as fuel, add it to the mixed solution of metal salt obtained in step 1), the molar ratio of fuel to total metal cations in the metal salt is 0.4 to 1.1:1; after stirring evenly at room temperature, place it in an oven to evaporate the water and obtain a mixed gel; 3) Place the mixed gel obtained in step 2) in a transparent electric furnace and react at 850 to 900℃ for 2 to 10 min to obtain a defect-rich rock salt type high-entropy oxide battery material.

2. The preparation method according to claim 1, characterized in that, In step 2), the temperature of the oven is controlled at 80-100℃.

3. A defect-rich rock-salt type high-entropy oxide battery material, prepared by the preparation method described in claim 1 or 2.

4. The application of the defect-rich rock-salt type high-entropy oxide battery material as described in claim 3 in the preparation of secondary battery anode materials.

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