A doped double-metal sulfide sodium-ion negative electrode material, a preparation method and application thereof, and a sodium-ion battery

Abstract

The application discloses a doped double-metal sulfide sodium ion negative electrode material and a preparation method and application thereof and a sodium ion battery, and relates to the technical field of sodium batteries. 3‑x Zn x Nb 1‑x Ti x S4, wherein 0<=x<0.5, the negative electrode material belongs to a tetragonal system, has an ordered vacancy vanadium copper sulfide structure, and the sodium ion negative electrode material is granular, the average size of the granules is 0.2-20 mu m, the specific capacity of the negative electrode material is 400-800 mAh / g, and the cycle life can be realized at 300-5000 times under a high current density of 1 A / g. The application further provides a preparation method of the sodium ion negative electrode material, which mainly uses a high-temperature solid-phase reaction, discards the use of dangerous chemical reagents, has simple preparation conditions, and has the advantages that the prepared sodium ion negative electrode material has a controllable structure and morphology, stable electrochemical performance and the like, and can be applied to the field of electrochemical sodium ion energy storage.

Description

Technical Field

[0001] This invention relates to the field of sodium battery technology, and in particular to a doped bimetallic sulfide sodium-ion anode material, its preparation method and application, and sodium-ion batteries. Background Technology

[0002] With the widespread deployment of renewable energy and the rapid development of electric transportation, the global demand for efficient, safe, and low-cost energy storage systems is increasing. Although lithium-ion batteries have been widely used in portable electronics and electric vehicles, their sustainable development in large-scale energy storage faces severe challenges due to the scarcity of lithium resources, continuously rising prices, and uneven geographical distribution. In contrast, sodium-ion batteries, with their abundant sodium resources, low cost, and electrochemical characteristics similar to lithium batteries, are gradually becoming one of the potential technological pathways to replace or supplement lithium-ion batteries.

[0003] Compared to the mature lithium-ion battery system, the development of sodium-ion batteries still faces many challenges, especially in terms of anode materials. Currently, widely studied anode material systems include hard carbon, metal oxides / sulfides, and alloy materials. Among them, hard carbon materials, as the most commercially promising anode, generally have a reversible specific capacity of 250-300 mAh / g, but suffer from low initial coulombic efficiency, poor rate performance, and the risk of sodium deposition under deep charging conditions at extremely low voltage plateaus. In contrast, metal oxides / sulfides and alloy materials (such as Sn, Sb, and Bi) have higher theoretical capacities, but these materials generally suffer from severe volume expansion and structural pulverization during sodium-ion intercalation / deintercalation, resulting in a cycle life typically less than 500 cycles. Therefore, developing novel anode materials that combine high capacity, good rate performance, and long cycle life is of great significance for promoting the development of sodium-ion batteries.

[0004] Cu3NbS4 is a typical bimetallic sulfide with a vanadium-copper oxide structure. It consists of three-dimensionally interconnected [NbS4] and [CuS4] tetrahedra sharing common edges / corners, exhibiting high structural stability and theoretical capacity, thus becoming a promising candidate material for sodium-ion batteries in recent years. However, Cu3NbS4 suffers from two main problems: firstly, its low electronic conductivity limits its rate performance; secondly, its crystal structure lacks stability during redox processes, making it difficult to balance specific capacity and cycle stability as an electrode material. To address these issues, previous studies have attempted to improve the electrochemical performance of Cu3NbS4 through nano-sizing and carbon coating, but these methods generally suffer from complex preparation processes, insufficient structural stability, or limited improvement in conductivity. Therefore, further improvements are needed. Summary of the Invention

[0005] To address the above shortcomings, this invention provides a doped bimetallic sulfide sodium-ion anode material, its preparation method, its application, and a sodium-ion battery. This sodium-ion anode material features controllable structural morphology and stable electrochemical performance, and its preparation method is simple, enabling its application in the field of electrochemical sodium-ion energy storage. The specific technical solution is as follows:

[0006] A sodium-ion anode material doped with a bimetallic sulfide, wherein the sodium-ion anode material has the following general formula: Cu 3-x Zn x Nb 1-x Ti x S4, where 0 < x < 0.5; the sodium ion anode material belongs to the cubic crystal system, has an ordered vacancy vanadium copper ore structure and a angular granular micromorphology, and its average particle size is 0.2~20μm.

[0007] Preferably, the Zn has a +2 valence and the Ti has a +4 valence, and the introduction of doping does not change the main crystal structure of the material.

[0008] The present invention also provides a method for preparing the above-mentioned doped bimetallic sulfide sodium-ion anode material, comprising: first weighing copper source, zinc source, niobium source, titanium source and sulfur source according to a certain molar ratio, mixing them, grinding them into powder, adding the powder into a pressing mold to press it into a sheet shape, then evacuating and sealing it in a glass tube, and carrying out a high-temperature solid-state reaction in a muffle furnace, that is, first heating to 400℃~1200℃ at a rate of 0.1℃ / min~10℃ / min, holding at the temperature for 0.2 hours~72 hours, and then cooling to room temperature at a rate of 2℃ / min~100℃ / min to obtain the sodium-ion anode material;

[0009] The total molar ratio of copper, zinc, niobium, titanium and sulfur in the sodium ion anode material is 3-x:x:1-x:x:4, where 0 < x < 0.5.

[0010] Preferably, the copper source is one or more of elemental copper and copper sulfides.

[0011] Preferably, the zinc source is one or more of elemental zinc and zinc sulfides.

[0012] Preferably, the niobium source is one or more of elemental niobium and niobium sulfides.

[0013] Preferably, the titanium source is one or more of elemental titanium and titanium sulfides.

[0014] Preferably, the sulfur source is elemental sulfur.

[0015] The present invention also provides a sodium-ion battery, wherein the sodium-ion battery comprises the sodium-ion anode material of the above-mentioned doped bimetallic sulfide.

[0016] This invention also provides the application of the above-mentioned doped bimetallic sulfide sodium-ion anode material in the field of sodium-ion batteries.

[0017] This invention constructs a novel Cu3-xZnxNb1-xTixS4 solid solution system by controllably introducing heterovalent metal ions Zn2+ and Ti4+ into a Cu3NbS4 matrix material. While maintaining the structural stability of the main crystalline phase, vanadium sulfide, this system achieves optimized electronic structure and significantly improved sodium ion diffusion kinetics through the introduction of electrons and holes via heterovalent doping. Simultaneously, it effectively alleviates the structural stress accumulation and crystal distortion caused by volume changes during sodium ion insertion / extraction. Specifically, Zn2+ (~0.74 Å) partially replaces Cu1+ (~0.77 Å) sites, and Ti4+ (~0.605 Å) partially replaces Nb5+ (~0.64 Å) sites, forming a charge-equivalent substitution and maintaining local charge neutrality of the crystal. On the one hand, the synergistic doping of Zn2+ / Ti4+ heterovalent ions effectively modulates the band structure of the material, reduces the band gap, and improves electron mobility, resulting in an electronic conductivity that is more than an order of magnitude higher than that of the original Cu3NbS4. On the other hand, the substitution of Nb5+ by Ti4+ weakens the strong Coulomb repulsion between high-valence Nb cations in the crystal. Simultaneously, the Ti-S bond has a higher valence than the Nb-S bond, making the [TiS4] tetrahedron more stable, thereby enhancing the material's resistance to distortion and effectively alleviating the local stress accumulation caused by sodium insertion / extraction during charge and discharge, enabling the material to exhibit excellent structure retention under long-term cycling. This material design overcomes the problems of poor electronic conductivity, low rate performance, and insufficient cycling stability inherent in existing Cu3NbS4 materials.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] 1. This invention uses copper, zinc, niobium, titanium, and sulfur sources as raw materials to obtain a sodium-ion anode material of the doped bimetallic sulfide through high-temperature solid-state reaction. This anode material has advantages such as controllable structural morphology and stable electrochemical performance, and can be used in the field of electrochemical sodium-ion energy storage. Specifically, the anode material obtained by this invention has a conductivity of 60 S / m to 200 S / m, a specific capacity of 400 to 800 mAh / g, and can achieve a cycle life of 300 to 5000 cycles at a high current density of 1 A / g.

[0020] 2. The preparation method of this invention eliminates the use of hazardous chemical reagents, and the doping method and synthesis process adopted are simple, controllable, and suitable for large-scale preparation. Attached Figure Description

[0021] 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.

[0022] Figure 1 This is a SEM image of the sodium-ion anode material of doped bimetallic sulfide prepared in Example 1 of the present invention.

[0023] Figure 2 The specific capacity and coulombic efficiency of the sodium-ion anode material of doped bimetallic sulfide prepared in Example 1 of the present invention are shown in the figure at different current densities.

[0024] Figure 3 The sodium-ion anode material of doped bimetallic sulfide prepared in Example 1 of this invention was tested at 1 A g. -1 The specific capacity and coulomb efficiency are shown below;

[0025] Figure 4 The specific capacity and coulombic efficiency of the sodium-ion anode material of bimetallic sulfide prepared in Comparative Example 1 of the present invention are shown in the figure at different current densities.

[0026] Figure 5 The sodium-ion anode material of bimetallic sulfide prepared for Comparative Example 1 of this invention was tested at 1 A g. -1 The specific capacity and coulomb efficiency are shown in the figure. Detailed Implementation

[0027] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0028] Example 1

[0029] Elemental copper powder, zinc powder, niobium powder, titanium powder, and sulfur powder were weighed according to a molar ratio of 2.8:0.2:0.8:0.2:4. The ground raw material powder was added to a pressing mold and pressed into a disc. After vacuuming, the disc was sealed in a glass tube and placed in a muffle furnace. The tube was heated to 600℃ at a rate of 3℃ / min and held for 12 hours. Then, it was cooled to room temperature at a rate of 5℃ / min to obtain a sodium ion anode material Cu2.8Zn0.2Nb0.8Ti0.2S4 with an ordered vacancy vanadium sulfide copper oxide structure and a angular granular microstructure with an average particle size of 2.8 μm. Figure 1 The conductivity is 78.56 S / m. The specific capacity of the doped bimetallic sulfide sodium-ion anode material prepared in this embodiment is 570 mAh / g. Figure 2 ), achieving a capacity retention of 96% after 1200 cycles at a high current density of 1 A / g. Figure 3 ).

[0030] Comparative Example 1

[0031] Elemental copper powder, niobium powder, and sulfur powder were weighed according to a molar ratio of 3.0:1.0:4. The ground raw material powder was added to a pressing mold and pressed into a disc. After vacuum sealing, the disc was placed in a glass tube and placed in a muffle furnace. The tube was heated to 600℃ at a rate of 3℃ / min and held for 12 hours. Then, it was cooled to room temperature at a rate of 5℃ / min. The resulting sodium-ion anode material Cu3NbS4, a doped bimetallic sulfide, had a angular granular microstructure with an average particle size of 2.7 μm and a conductivity of 5.73 S / cm. The specific capacity of the sodium-ion anode material doped bimetallic sulfide prepared in this comparative example was 515 mAh / g. Figure 4 ), achieving a capacity retention of 65% after 700 cycles at a high current density of 1 A / g. Figure 5 ).

[0032] As can be seen from Example 1 and Comparative Example 1, the sodium-ion anode material of doped bimetallic sulfide prepared in this invention exhibits higher specific capacity and cycle life in sodium-ion batteries.

[0033] Example 2

[0034] Elemental copper powder, zinc powder, niobium powder, titanium powder, and sulfur powder were weighed according to a molar ratio of 2.95:0.05:0.95:0.05:4. The ground raw material powder was added to a pressing mold and pressed into discs. After vacuum sealing, the discs were placed in a glass tube and placed in a muffle furnace. The tubes were heated to 700°C at a rate of 10°C / min and held for 36 hours. Then, they were cooled to room temperature at a rate of 20°C / min. The resulting doped bimetallic sulfide sodium-ion anode material Cu2.95Zn0.05Nb0.95Ti0.05S4 exhibited a well-defined granular microstructure with an average particle size of 3.5 μm and a conductivity of 125 S / m. The doped bimetallic sulfide sodium-ion anode material prepared in this embodiment had a specific capacity of 550 mAh / g and achieved a capacity retention of 85% after 3000 cycles at a high current density of 1 A / g.

[0035] Example 3

[0036] Elemental copper powder, zinc powder, niobium powder, titanium powder, and sulfur powder were weighed according to a molar ratio of 2.85:0.15:0.85:0.15:4. The ground raw material powder was added to a pressing mold and pressed into discs. After vacuum sealing, the discs were placed in a glass tube and placed in a muffle furnace. The tubes were heated to 900°C at a rate of 1°C / min and held for 48 hours. Then, they were cooled to room temperature at a rate of 50°C / min. The resulting doped bimetallic sulfide sodium-ion anode material, Cu2.85Zn0.15Nb0.85Ti0.15S4, exhibited a angular granular microstructure with an average particle size of 3.2 μm and a conductivity of 145 S / m. The doped bimetallic sulfide sodium-ion anode material prepared in this embodiment had a specific capacity of 560 mAh / g and achieved a capacity retention of 82% after 5000 cycles at a high current density of 1 A / g.

[0037] Example 4

[0038] Cuprous sulfide, zinc sulfide, niobium pentasulfide, and titanium disulfide were weighed according to a molar ratio of 1.35:0.3:0.35:0.3. The ground raw material powder was added to a pressing mold and pressed into discs. After vacuuming, the discs were sealed in glass tubes and placed in a muffle furnace. The furnace was heated to 950°C at a rate of 5°C / min and held for 40 hours. Then, the discs were cooled to room temperature at a rate of 100°C / min. The resulting doped bimetallic sulfide sodium-ion anode material, Cu2.7Zn0.3Nb0.7Ti0.3S4, exhibited a angular granular microstructure with an average particle size of 1.2 μm and a conductivity of 165 S / m. The doped bimetallic sulfide sodium-ion anode material prepared in this embodiment had a specific capacity of 740 mAh / g and achieved a capacity retention of 82% after 2000 cycles at a high current density of 1 A / g.

[0039] Example 5

[0040] Cuprous sulfide, zinc sulfide, niobium pentasulfide, and titanium disulfide were weighed according to a molar ratio of 1.3:0.4:0.6:0.4. The ground raw material powder was added to a pressing mold and pressed into discs. After vacuum sealing, the discs were placed in a glass tube and placed in a muffle furnace. The furnace was heated to 500°C at a rate of 2°C / min and held for 72 hours. The temperature was then lowered to room temperature at a rate of 2°C / min. The resulting doped bimetallic sulfide sodium-ion anode material, Cu2.6Zn0.4Nb0.6Ti0.4, exhibited a well-defined granular microstructure with an average particle size of 3.0 μm and a conductivity of 189 S / m. The doped bimetallic sulfide sodium-ion anode material prepared in this embodiment had a specific capacity of 780 mAh / g and achieved a capacity retention of 84% after 1000 cycles at a high current density of 1 A / g.

[0041] In summary, this invention uses copper, zinc, niobium, titanium, and sulfur sources as raw materials to obtain the doped bimetallic sulfide sodium-ion anode material through high-temperature solid-state reaction. This anode material has advantages such as controllable structural morphology and stable electrochemical performance, and can be used in the field of electrochemical sodium-ion energy storage. Specifically, the anode material obtained by this invention has a conductivity of 60 S / m to 200 S / m, a specific capacity of 400 to 800 mAh / g, and can achieve a cycle life of 300 to 5000 cycles at a high current density of 1 A / g. Furthermore, the preparation method of this invention eliminates the use of hazardous chemical reagents, and the doping method and synthesis process are simple, controllable, and suitable for large-scale preparation.

[0042] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A sodium-ion anode material doped with a bimetallic sulfide, characterized in that, The sodium ion anode material has the following general formula: Cu 3-x Zn x Nb 1-x Ti x S4, where 0 < x < 0.5; the sodium ion anode material belongs to the cubic crystal system and has an ordered vacancy vanadium copper oxide structure. The sodium ion anode material is granular with an average particle size of 0.2~20μm.

2. The sodium-ion anode material of a doped bimetallic sulfide according to claim 1, characterized in that, The Zn has a +2 valence and the Ti has a +4 valence, and the introduction of doping does not change the main crystal structure of the material.

3. A method for preparing a sodium-ion anode material of a doped bimetallic sulfide as described in any one of claims 1-2, characterized in that, include: First, copper source, zinc source, niobium source, titanium source and sulfur source are weighed and mixed according to a certain molar ratio, and then ground into powder. The powder is added into a tableting mold and pressed into a tablet shape. Then, after vacuuming, it is sealed in a glass tube and carried out in a muffle furnace for high-temperature solid-phase reaction. That is, it is first heated to 400℃~1200℃ at a rate of 0.1℃ / min~10℃ / min, held at the temperature for 0.2 hours~72 hours, and then cooled to room temperature at a rate of 2℃ / min~100℃ / min to obtain the sodium ion anode material. The total molar ratio of copper, zinc, niobium, titanium and sulfur in the sodium ion anode material is 3-x:x:1-x:x:4, where 0 < x < 0.

5.

4. The method for preparing a sodium-ion anode material of a doped bimetallic sulfide according to claim 3, characterized in that, The copper source is one or more of elemental copper and copper sulfides.

5. The method for preparing a sodium-ion anode material of a doped bimetallic sulfide according to claim 3, characterized in that, The zinc source is one or more of elemental zinc and zinc sulfides.

6. The method for preparing a sodium-ion anode material of a doped bimetallic sulfide according to claim 3, characterized in that, The niobium source is one or more of elemental niobium and niobium sulfides.

7. The method for preparing a sodium-ion anode material of a doped bimetallic sulfide according to claim 3, characterized in that, The titanium source is one or more of elemental titanium and titanium sulfides.

8. The method for preparing a sodium-ion anode material of a doped bimetallic sulfide according to claim 3, characterized in that, The sulfur source is elemental sulfur.

9. A sodium-ion battery, characterized in that, The sodium-ion battery includes the negative electrode material as described in any one of claims 1 to 8.

10. The application of a sodium-ion anode material of a doped bimetallic sulfide as described in any one of claims 1 to 8 in the field of sodium-ion batteries.

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