Preparation method and application of ruthenium disulfide-copper pentasulfide positive electrode material

Abstract

This invention belongs to the technical field of magnesium-ion battery materials, specifically to a method for preparing ruthenium disulfide-copper pentasulfide (Cu9S5-RuS2) cathode material for magnesium-ion batteries. This method utilizes a simple hydrothermal synthesis technique, using copper dichloride dihydrate, thiourea, and ruthenium trichloride as raw materials to successfully synthesize Cu9S5-RuS2. This Cu9S5-RuS2, as a cathode material for magnesium-ion batteries, exhibits excellent electrochemical performance. Furthermore, the preparation process is simple to operate, contributing to the advancement and commercialization of magnesium-ion battery technology.

Description

Technical Field

[0001] The present invention belongs to the technical field of magnesium ion battery materials, and particularly relates to a preparation method of a ruthenium disulfide-copper pentasulfide electrode material and an application thereof as a positive electrode material for a magnesium ion battery. Background Art

[0002] The global energy crisis is intensifying. Fossil fuel depletion and price fluctuations are leading to unstable energy supplies, while climate change is driving demand for clean energy. The world faces the urgent challenge of transitioning from traditional to renewable energy sources. While widely used, lithium batteries also have drawbacks such as safety concerns, high costs, limited resources, and environmental impacts.

[0003] In contrast, magnesium-ion batteries (Mg-ion batteries) show great potential in the energy storage field due to their unique advantages. Magnesium is abundant and low-cost, and the divalent nature of magnesium ions theoretically allows for a higher volumetric capacity than lithium batteries. Furthermore, Mg-ion batteries are less susceptible to dendrite formation, reducing the risk of short circuits and thermal runaway. Furthermore, magnesium materials are non-toxic and easily recyclable, reducing environmental pollution. Furthermore, the long cycle life and stability of Mg-ion batteries across a wide temperature range make them suitable for a variety of environments and applications.

[0004] Despite this, magnesium-ion batteries still face numerous challenges, including a shortage of cathode materials, electrolyte-cathode material compatibility issues, high deposition overpotentials, and low charge-discharge efficiency. The slow diffusion of magnesium ions within the material limits the battery's charge-discharge performance. Currently, magnesium-ion battery technology is still in its developmental stages, and further research is needed to improve its performance and reliability.

[0005] Current research on magnesium-ion batteries focuses primarily on three aspects: cathode materials, electrolytes, and anode materials. Optimizing cathode materials can enhance the diffusion rate and charge storage capacity of magnesium ions, reduce overpotential, and improve battery efficiency. Sulfide cathode materials, due to their high electrochemical activity and low charge density, facilitate the diffusion and migration of magnesium ions. The "soft" anion lattice of sulfide can weaken the Coulomb attraction between the crystal structure and magnesium ions, thereby promoting the accelerated diffusion and reversible insertion of magnesium ions. These properties enable sulfide cathode materials to exhibit rapid charge and discharge capabilities and excellent electrochemical performance in magnesium-ion batteries.

[0006] Based on this, this application was developed. Summary of the Invention

[0007] The purpose of the present invention is to address the defects and shortcomings of current magnesium-ion batteries and provide a ruthenium disulfide-copper pentasulfide (Cu9S5-RuS2) positive electrode material. The material has a regular morphology and exhibits a nanotube structure, which facilitates the rapid insertion and extraction of magnesium ions. The magnesium-ion battery assembled using this material exhibits excellent electrochemical performance. At a current density of 100 mA / g, the battery still has a discharge specific capacity of 118.8 mAh / g after 300 cycles, and the capacity retention rate is 42.2%.

[0008] The present invention also provides a method for preparing the above-mentioned ruthenium disulfide-copper pentasulfide (Cu9S5-RuS2) positive electrode material, which is simple and economical to prepare and can significantly improve the performance of the battery.

[0009] The present invention also provides the use of the above-mentioned ruthenium disulfide-copper pentasulfide (Cu9S5-RuS2) positive electrode material as a positive electrode material for a magnesium ion battery.

[0010] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0011] A method for preparing a ruthenium disulfide-copper pentasulfide positive electrode material comprises the following steps:

[0012] Dissolve copper dichloride dihydrate, thiourea and ruthenium trichloride in water, and then react at a temperature of 160-200°C for 4-10 hours. After the reaction is completed, separate the solid and liquid, wash and dry to obtain the product.

[0013] Specifically, the mass ratio of the copper dichloride dihydrate, thiourea and ruthenium trichloride can be 1:0.2~0.3:0.1~0.2.

[0014] As a preferred method, the preparation method of the above-mentioned ruthenium disulfide-copper pentasulfide positive electrode material comprises the following steps:

[0015] (1) Raw material preparation: Dissolve copper dichloride dihydrate and thiourea in water separately (stir for 2-4 hours to form the solution required for the reaction, ensuring complete dissolution and uniform mixing), obtain copper dichloride dihydrate solution and thiourea solution, mix the two, and then mix with ruthenium trichloride solution;

[0016] (2) Solution transfer and high-temperature reaction: Transfer the above liquid to a stainless steel reactor, place it in a muffle furnace, heat it to 160-200 °C and maintain this temperature for 4-10 h;

[0017] (3) Cooling and separation: After the reaction is completed, the reactor is naturally cooled to room temperature, and the solid product is separated by filtration;

[0018] (4) Washing and drying: Wash the solid product with deionized water and anhydrous ethanol respectively to remove impurities, and finally dry it.

[0019] Specifically, the concentration of the cupric chloride dihydrate solution in step (1) may preferably be 0.071 to 0.094 mol / L. The concentration of the thiourea solution may preferably be 0.040 to 0.049 mol / L. The concentration of the ruthenium trichloride solution may preferably be 0.011 to 0.023 mol / L. In step (2), the liquid occupies no more than 80% of the capacity of the stainless steel reactor.

[0020] Furthermore, in step (4), the product may be first washed with deionized water for 3 to 5 times, and then washed with anhydrous ethanol for 3 to 5 times; the drying process is performed in a vacuum drying oven at a drying temperature of 45 to 80°C for a drying time of not less than 12 h.

[0021] The present invention provides a ruthenium disulfide-copper pentasulfide positive electrode material prepared by the above method.

[0022] The present invention provides the use of the above-mentioned ruthenium disulfide-copper pentasulfide positive electrode material as a positive electrode material for magnesium ion batteries in the preparation of magnesium ion batteries.

[0023] The present invention also provides a magnesium ion battery comprising the above-mentioned ruthenium disulfide-copper pentasulfide positive electrode material.

[0024] Compared with the prior art, the beneficial effects of the present invention are mainly reflected in the following aspects:

[0025] 1. The present invention provides a simple and cost-effective method for preparing ruthenium disulfide-copper pentasulfide (Cu9S5-RuS2) cathode material.

[0026] 2. The ruthenium disulfide-copper pentasulfide (Cu9S5-RuS2) prepared by the method of the present invention has a regular morphology and exhibits a nanotube structure, which facilitates the rapid insertion and extraction of magnesium ions.

[0027] 3. Test results show that a magnesium-ion battery assembled using the ruthenium disulfide-copper pentasulfide (Cu9S5-RuS2) cathode material prepared in this invention exhibits excellent electrochemical performance. At a current density of 100 mA / g, the battery maintained a discharge capacity of 118.8 mAh / g after 300 cycles, with a capacity retention rate of 42.2%. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a scanning electron microscope (SEM) image of ruthenium disulfide-copper pentasulfide prepared in Example 1;

[0029] Figure 2 This is the elemental analysis (EDS) diagram of ruthenium disulfide-copper pentasulfide prepared in Example 1;

[0030] Figure 3 A cyclic voltammetry curve of a magnesium ion battery assembled with ruthenium disulfide-copper pentasulfide prepared in Example 1 as the positive electrode material at a scan rate of 1.0 mV / s;

[0031] Figure 4 The charge and discharge curves of a magnesium ion battery assembled with ruthenium disulfide-copper pentasulfide prepared in Example 1 as the positive electrode material at different current densities;

[0032] Figure 5 This is a charge-discharge curve of a magnesium-ion battery assembled with ruthenium disulfide-copper pentasulfide prepared in Example 1 as the positive electrode material at different cycle numbers at a current density of 50 mA / g;

[0033] Figure 6 This is a cycling stability curve of a magnesium ion battery assembled with ruthenium disulfide-copper pentasulfide prepared in Example 1 as the positive electrode material at a current density of 100 mA / g. DETAILED DESCRIPTION

[0034] The technical solution of the present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited to the embodiments described below.

[0035] Through these embodiments, we hope to more comprehensively demonstrate the technical details and application effects of the present invention, but the actual application scope of the present invention may be broader and not limited to the following description.

[0036] In the following examples, unless otherwise specified, the raw materials used are common commercial products that can be purchased directly or can be prepared using conventional techniques in the art.

[0037] Room temperature refers to 25±5℃.

[0038] Example 1

[0039] A method for preparing a ruthenium disulfide-copper pentasulfide positive electrode material, wherein the specific implementation steps are as follows:

[0040] 0.2 g of CuCl2·2H2O was dissolved in 15 mL of water (stirred for 3 hours to promote complete dissolution), and 0.0468 g of thiourea was dissolved in 15 mL of water (stirred for 3 hours to promote complete dissolution). The copper dichloride dihydrate solution and thiourea solution were then mixed together, ultrasonicated to ensure uniform mixing, and stirred for 3 hours to promote dissolution, resulting in mixed solution A. 0.0239 g of RuCl3 was dissolved in 10 mL of water to obtain mixed solution B. Mixed solutions A and B were then mixed and transferred to a stainless steel reactor. The reactor was placed in a muffle furnace and heated to 180°C for 6 hours. After completion of the reaction, the reaction mixture was cooled to room temperature and filtered to separate the solid product. The solid product was then washed four times with deionized water and four times with anhydrous ethanol. The washed product was dried in a vacuum oven at 60°C for 24 hours to obtain the ruthenium disulfide-copper pentasulfide (Cu9S5-RuS2) cathode material.

[0041] Figure 1 The scanning electron microscope (SEM) image of ruthenium disulfide-copper pentasulfide prepared in Example 1 is given. Figure 1 As shown, the microscopic morphology of ruthenium disulfide-copper pentasulfide (Cu9S5-RuS2) prepared in this embodiment presents a nanotube structure, and these nanotubes are aggregated by multiple nanospheres.

[0042] Figure 2 The elemental analysis (EDS) diagram of ruthenium disulfide-copper pentasulfide prepared in Example 1 is given. Figure 2 As shown, the energy spectrum of ruthenium disulfide-copper pentasulfide (Cu9S5-RuS2) prepared in this embodiment shows that the material is mainly composed of Cu, Ru and S elements.

[0043] Example 2

[0044] The ruthenium disulfide-copper pentasulfide positive electrode material prepared in Example 1 is applied to a magnesium ion battery in the following steps:

[0045] Positive Electrode Preparation: The Cu9S5-RuS2 electrode sheet was primarily prepared by mixing Cu9S5-RuS2, conductive carbon black, and polyvinylidene fluoride (PVDF) in a mass ratio of 7:2:1. Specifically, 0.01 g of PVDF was added to 1.5 mL of NMP (N-methylpyrrolidone) and mixed thoroughly to obtain a PVDF-NMP solution. The conductive carbon black and the Cu9S5-RuS2 prepared in Example 1 were then added to the PVDF-NMP solution and stirred for 6 hours. The resulting slurry was then coated onto a 12 mm diameter carbon cloth current collector and dried in a 60°C forced air oven for 30 minutes. The resulting slurry was then transferred to a vacuum drying oven and dried at 120°C for 6 hours.

[0046] Assembly: The battery was assembled using a CR2032 button cell case. A commercial magnesium sheet with a thickness of 2.5 mm and a diameter of 14 mm was used as the negative electrode, a glass fiber membrane with a diameter of 16 mm was used as the separator, a carbon cloth current collector with a diameter of 12 mm and loaded with Cu9S5-RuS2 prepared in Example 1 was used as the positive electrode, and Mg(TFSI)2-AlCl3-MgCl2-DME was used as the electrolyte (for the specific electrolyte formula, see Xiaolan Xue, et al., Boosting the cycling stability of rechargeable magnesium batteries by regulating the compatibility between nanostructural metal sulfide cathodes and non-nucleophilic electrolytes, DOI:10.1007 / s12274-022-4932-z, Volume 16, pages 2399–2408, (2023)). The assembly is carried out in the order of negative electrode shell, spring, gasket, magnesium sheet, electrolyte, diaphragm, electrolyte, positive electrode sheet, gasket, and positive electrode shell. The assembly process is carried out in a glove box filled with argon (H2O and O2 < 0.01 ppm).

[0047] Cyclic voltammetry: An electrochemical workstation (CHI 660E, Shanghai Chenhua) was used to study the peak positions of the oxidation / reduction reactions of the battery during the cycling process. The test voltage range was 0–2.5 V, and the scan rate was 1 mV s −1 .

[0048] Rate performance test: Wuhan LAND CT3002A battery testing system was used to conduct charge and discharge tests at current densities of 50 mA / g, 100 mA / g, 200 mA / g, and 500 mA / g.

[0049] Cycling performance test: The Wuhan LAND CT3002A battery testing system was used to test the constant current charge and discharge performance of the button battery at a current density of 50 mA / g; the cycling stability performance of the button battery was tested at a current density of 100 mA / g, and the number of cycles was set to 300.

[0050] Figure 3 The cyclic voltammetry curve of the magnesium ion battery assembled with ruthenium disulfide-copper pentasulfide as the positive electrode material prepared in Example 1 at a scan rate of 1.0 mV / s is given. Figure 3As shown, the assembled battery was subjected to cyclic voltammetry testing, and it can be clearly seen that: a highly reversible Mg deposition / dissolution process, and with the increase in the number of cycles, the redox peak position did not shift significantly, and the CV curves almost overlapped, showing good reversibility of the Mg storage reaction.

[0051] Figure 4 The charge and discharge curves of the magnesium ion battery assembled with ruthenium disulfide-copper pentasulfide as the positive electrode material prepared in Example 1 at different current densities are given. Figure 4 As shown, the assembled battery was tested at different rates. By observing the charge and discharge curves at different current densities, the discharge and charge platforms can be clearly seen, which shows that the battery has excellent structural stability.

[0052] Figure 5 The charge and discharge curves of the magnesium ion battery assembled with ruthenium disulfide-copper pentasulfide as the positive electrode material prepared in Example 1 are given at different cycle times at a current density of 50 mA / g. Figure 5 As shown, at a current density of 50 mA / g, the charge and discharge platform of the assembled battery does not change much with the increase in the number of cycles, showing good stability. The specific capacity of the battery is always maintained above 200 mAh / g, which indicates that the battery has a high energy storage capacity.

[0053] Figure 6 The cycle stability curve of the magnesium ion battery assembled with ruthenium disulfide-copper pentasulfide as the positive electrode material prepared in Example 1 at a current density of 100 mA / g is given. Figure 6 As shown in the figure, the assembled battery still has a discharge capacity of 118.8 mAh / g after 300 cycles at a current density of 100 mA / g, and the capacity retention rate is 42.2%.

[0054] In summary, the preparation method of the ruthenium sulfide-copper pentasulfide (Cu9S5-RuS2) cathode material of the present invention is not only simple and economical, but also effectively improves battery performance, including stability at different current densities and cycle life, which is of great significance for the development and application of battery technology.

[0055] The above embodiments are only preferred embodiments of the present invention, but this does not mean that these embodiments limit the scope of protection of the invention. Any non-substantial changes, improvements or replacements made on the basis of the present invention, as long as these changes do not exceed the core concept and technical solution of the invention, are within the scope of protection required by the invention.

Claims

1. A method for preparing a ruthenium disulfide-copper pentasulfide positive electrode material, characterized in that: Dissolve copper dichloride dihydrate, thiourea, and ruthenium trichloride in water, then react in a stainless steel reactor at 160-200°C for 4-10 hours. After the reaction is complete, separate the solid and liquid, wash, and dry to obtain the product. The mass ratio of the copper dichloride dihydrate, thiourea and ruthenium trichloride is 1:0.2-0.3:0.1-0.

2.

2. The method for preparing the ruthenium disulfide-copper pentasulfide positive electrode material according to claim 1, characterized in that: The following steps are involved: (1) Raw material preparation: Dissolve copper dichloride dihydrate and thiourea in water to obtain copper dichloride dihydrate solution and thiourea solution, mix the two, and then mix with ruthenium trichloride solution; (2) Solution transfer and high-temperature reaction: Transfer the above liquid to a stainless steel reactor, place it in a muffle furnace, heat it to 160-200 °C and maintain this temperature for 4-10 h; (3) Cooling and separation: After the reaction is completed, the reactor is naturally cooled to room temperature, and the solid product is separated by filtration; (4) Washing and drying: Wash the solid product with deionized water and anhydrous ethanol respectively, and finally dry it.

3. The method for preparing the ruthenium disulfide-copper pentasulfide positive electrode material according to claim 2, characterized in that: The concentration of the copper dichloride dihydrate solution in step (1) is 0.071-0.094 mol / L.

4. The method for preparing the ruthenium disulfide-copper pentasulfide positive electrode material according to claim 2, characterized in that: The concentration of the thiourea solution in step (1) is 0.040-0.049 mol / L.

5. The method for preparing the ruthenium disulfide-copper pentasulfide positive electrode material according to claim 2, characterized in that: The concentration of the ruthenium trichloride solution in step (1) is 0.011-0.023 mol / L.

6. The method for preparing the ruthenium disulfide-copper pentasulfide positive electrode material according to claim 2, characterized in that: In the step (4), the product is first washed with deionized water for 3 to 5 times, and then washed with anhydrous ethanol for 3 to 5 times; the drying process is carried out in a vacuum drying oven at a drying temperature of 45 to 80°C for a drying time of not less than 12 hours.

7. Ruthenium disulfide-copper pentasulfide positive electrode material prepared by the method according to any one of claims 1 to 6.

8. Use of the ruthenium disulfide-copper pentasulfide positive electrode material according to claim 7 as a positive electrode material for a magnesium ion battery in the preparation of a magnesium ion battery.

9. A magnesium ion battery, characterized in that: Contains the ruthenium disulfide-copper pentasulfide positive electrode material according to claim 7.

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