A W-doped magnesium-ion battery cathode material W inducing multi-electron reactions 0.05 V 0.95 S4

Abstract

The application discloses a W-doped magnesium ion battery positive electrode material W 0.05 V 0.95 S4, and belongs to the technical field of battery materials. Ammonium metavanadate and ammonium tungstate are mixed in a proper ratio to prepare an aqueous solution, then the aqueous solution is mixed with excessive thioacetamide ethylene glycol solution, and then is transferred into a reaction kettle to perform hydrothermal reaction at 200 DEG C for 4h; the product is dried to obtain the magnesium ion battery positive electrode material W 0.05 V 0.95 S4. The W-doping can not only make the electrode material have multi-electron reactions of V 2+ / V 3+ , V 3+ / V 4+ , V 4+ / V 5+ during magnesium storage, but also can keep the structure stability of the positive electrode material during magnesium storage by regulating the morphology of the flower-shaped microspheres, so that the electrochemical performance of the magnesium ion battery is improved. The magnesium ion battery assembled from the material has high specific capacity and excellent cycle stability, and has wide application prospect.

Description

Technical Field

[0001] This invention relates to the field of battery materials technology, specifically to a magnesium-ion battery cathode material W doped with W to induce multi-electron reactions. 0.05 V 0.95 S4. Background Technology

[0002] In recent years, magnesium-ion batteries have developed rapidly and are expected to become the next generation of ion batteries due to their advantages such as low reduction potential, high theoretical specific capacity, and high volumetric specific capacity. However, the strong electrostatic interaction between divalent magnesium ions and cathode materials leads to slow diffusion kinetics within the cathode material, resulting in insufficient activation of internal sites and incomplete magnesium storage reaction. Therefore, modifying the cathode material to facilitate a more complete magnesium storage reaction is a major challenge in developing magnesium-ion batteries with high electrochemical performance.

[0003] VS4, a typical transition metal sulfide, has a vitamin V valence of +4, which can change from +2 to +5 depending on the electronic environment. Furthermore, VS4 possesses a unique linear chain structure with an inter-chain spacing of 0.56 nm, larger than the effective diameter of a magnesium ion. It is conducive to the diffusion of magnesium ions. Therefore, VS4 is considered a promising cathode material for magnesium-ion batteries. However, VS4 undergoes a typical single-electron transfer process during magnesium storage, in which V mainly undergoes V0 electron transfer during magnesium storage. 4+ / V 5+The reversible changes in VS4 have been verified in existing reports (see: Morphology-dependent electrochemical performance of VS4 for rechargeable magnesium battery and its magnesiation / demagnesiation mechanism, Li et al. J. Power Sources, 2020, 451, 227815). Therefore, VS4 can be modified to achieve multi-electron reactions, thereby improving its specific capacity. However, the large volume changes caused by multi-electron reactions make it difficult for the host material to maintain its structural stability, which limits the cycle reversibility and stability of magnesium-ion batteries (see: Hetero-layered MoS2 / C composites enabling ultrafast and durable Na storage, Li et al. Energy Storage Mater. 2019, 21, 115-123).

[0004] This invention utilizes a solvothermal method to induce W doping in a VS4 structure and investigates the effects of W doping. 0.05 V 0.95 The study investigated the multi-electron reaction process and electrochemical performance of S4 as a cathode material in magnesium-ion batteries. A series of characterization results showed that W doping can induce both flower-like microsphere morphology and V doping. 2+ and V 3+ The existence of a low-valence state V will cause it to occur during the V process. 4+ / V 5+ During the reaction, V can also be carried out. 2+ / V 3+ V 3+ / V 4+ V 4+ / V 5+ A deeper and more thorough magnesium storage reaction allows W 0.05 V 0.95 S4 undergoes multi-electron reactions during magnesium storage. Electrochemical performance analysis shows that, due to the multi-electron reactions induced by W doping and changes in microstructure, the W-doped magnesium-ion battery cathode material exhibits enhanced performance. 0.05 V 0.95 The specific capacity, rate performance, and cycle performance of S4 have all been improved. (At 50 mA g) -1 At current density, W 0.05 V 0.95 The S4 exhibits a capacity close to 150mAh. -1 It has a high specific capacity. And at 1000 mA g... -1At current densities, it exhibits excellent rate performance, and after 1500 cycles, its capacity retention reaches 95%. Summary of the Invention

[0005] The purpose of this invention is to provide a magnesium-ion battery cathode material, and more particularly to provide a magnesium-ion battery cathode material W doped to induce multi-electron reactions. 0.05 V 0.95 S4. W obtained after W doping modification. 0.05 V 0.95 The S4 magnesium-ion battery cathode material achieves multi-electron reactions while maintaining the stability of the cathode material structure, exhibiting high specific capacity and good cycle stability.

[0006] To achieve the above-mentioned objectives, the present invention provides a magnesium-ion battery cathode material W. 0.05 V 0.95 The preparation process of S4 is as follows:

[0007] 1. Dissolve ammonium metavanadate in deionized water under stirring at 60°C, and add ammonium tungstate at a molar ratio of 0.5% to ammonium metavanadate to obtain a mixed solution A with an ammonium metavanadate concentration of 0.167M;

[0008] 2. Weigh out excess thioacetamide and dissolve it in an equal volume of ethylene glycol as solution A, stirring until completely dissolved to obtain solution B;

[0009] 3. Mix solution A and solution B, and stir at 60°C until the two solutions are completely mixed;

[0010] 4. Transfer the thoroughly mixed solution to a 100ml reaction vessel, heat to 200℃, react for 4 hours, and then cool to room temperature with the furnace after the reaction is complete;

[0011] 5. Remove the sample after the reaction, wash it three times with deionized water and anhydrous ethanol respectively, and place the obtained product in a vacuum drying oven to dry at 60℃ for 12 hours to obtain the magnesium-ion battery cathode material W. 0.05 V 0.95 S4.

[0012] This invention also provides W 0.05 V 0.95 S4 was used as a positive electrode material in magnesium-ion batteries, and it was assembled into a coin cell with a magnesium anode, a glass fiber separator, and an APC-THF electrolyte. After the assembled battery was left to stand for 24 hours, its electrochemical performance was tested on a CT2001A battery programmable tester. The test voltage window was 0.2–2.1 V, and the current density was 50 and 1000 mAg. -1 .

[0013] The magnesium-ion battery cathode material W provided by this invention0.05 V 0.95 The advantage of S4 is:

[0014] 1. The magnesium-ion battery cathode material W prepared by this invention 0.05 V 0.95 S4, W doping can induce V 2+ and V 3+ The generation of V 2+ and V 3+ The existence of V 2+ / V 3+ V 3+ / V 4+ V 4+ / V 5+ The reaction process can proceed in W 0.05 V 0.95 The S4 magnesium-ion battery cathode material achieves multi-electron reactions, compared to the V-type reactions alone. 4+ / V 5+ In single-electron reactions, the magnesium storage reaction proceeds more completely, therefore W 0.05 V 0.95 The S4 magnesium-ion battery cathode material exhibits a high specific capacity.

[0015] 2. The magnesium-ion battery cathode material W prepared by this invention 0.05 V 0.95 S4 and W-doped flower-like microspheres possess a large specific surface area and porosity, which can improve the utilization rate of active materials and release the large internal stress generated during multi-electron magnesium storage to maintain structural stability. Therefore, W 0.05 V 0.95 The S4 magnesium-ion battery cathode material exhibits enhanced cycle stability.

[0016] 3. The magnesium-ion battery cathode material W prepared by this invention 0.05 V 0.95 S4 exhibits excellent electrochemical performance: at 50 mA g -1 At current density, W 0.05 V 0.95 The S4 exhibits a capacity close to 150mAh g. -1 High specific capacity. At 1000 mA g -1 At a current density of 1500 cycles, the electrode material retains 95% of its capacity, demonstrating excellent cycle stability.

[0017] The following description, in conjunction with the accompanying drawings, further illustrates the concept, structure, and technical effects of the present invention. Attached Figure Description

[0018] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings:

[0019] Figure 1 The magnesium-ion battery cathode material W obtained in the examples 0.05 V 0.95 High-resolution XPS spectra of S4 in W;

[0020] Figure 2 The magnesium-ion battery cathode material W obtained in the examples 0.05 V 0.95 SEM images of S4;

[0021] Figure 3 The magnesium-ion battery cathode material W obtained in the examples 0.05 V 0.95 TEM image of S4;

[0022] Figure 4 The magnesium-ion battery cathode material W obtained in the examples 0.05 V 0.95 S4 in V high-resolution XPS spectrum;

[0023] Figure 5 The magnesium-ion battery cathode material W obtained in the examples 0.05 V 0.95 S4 V high-resolution XPS spectra at different cutoff voltages;

[0024] Figure 6 The magnesium-ion battery cathode material W obtained in the examples 0.05 V 0.95 S4's rate and cycle performance diagram. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to specific embodiments, but the embodiments do not limit the scope of the present invention in any way.

[0026] Example

[0027] 0.5849 g of ammonium metavanadate was dissolved in 30 ml of deionized water, and 0.0064 g of ammonium tungstate was added. The mixture was stirred at 60 °C until completely dissolved to obtain solution A. Excess thioacetamide was dissolved in 30 ml of ethylene glycol and stirred at room temperature until completely dissolved to obtain solution B. Solution B and solution A were thoroughly mixed at 60 °C. The mixture was transferred to a 100 ml reactor and subjected to a hydrothermal reaction at 200 °C for 4 h, followed by furnace cooling to room temperature. The sample was removed, rinsed three times with deionized water and anhydrous ethanol, and dried in a vacuum drying oven at 60 °C for 12 h to obtain magnesium-ion battery cathode material W.0.05 V 0.95 S4.

[0028] After the solvothermal reaction, obvious signal peaks can be observed in the high-resolution XPS spectrum of W, proving that W has been successfully doped into VS4. Figure 1 W doping induced a change in the morphology of VS4, causing it to exhibit a flower-like microsphere morphology. Figure 2 , 3 High-resolution XPS spectra of V ( Figure 4 The V element displays the V element in addition to having V. 4+ In addition to the peak, V is also shown 2+ and V 3+ The peak indicates that W doping induced V 2+ and V 3+ The generation of W. 0.05 V 0.95 High-resolution XPS spectra of V at different cutoff voltages for S4 ( Figure 5 The analysis yields the following results: during the discharge process, V 2+ Gradually disappearing, V 3+ V 4+ V 5+ Gradually, during the charging process, the valence state of element V also changes from V... 5+ Gradually change to V 4+ , and then continue from V 4+ Change to V 3+ Then change to V 2+ Prove W 0.05 V 0.95 S4 cathode material V 2+ / V 3+ V 3+ / V 4+ V 4+ / V 5+ The reaction process further proves that the multi-electron reaction occurs in W. 0.05 V 0.95 In S4 cathode material.

[0029] The prepared W 0.05 V 0.95 S4 was used as the positive electrode material for the magnesium-ion battery, polished magnesium foil was used as the negative electrode material, a glass fiber filter membrane was used as the separator, and 0.4M APC-THF was used as the electrolyte. The batteries were assembled into coin cells in a glove box filled with high-purity argon. After the assembled magnesium-ion batteries were allowed to stand for 24 hours, their electrochemical performance was tested using a CT2001A battery programmable tester. The test voltage window was 0.2–2.1V, and the current densities were 50 and 1000 mAg. -1 .

[0030] The resulting magnesium-ion battery cathode material W 0.05 V 0.95 S4 at a current density of 50 mAg -1 At that time, it showed 149.3 mAhg -1 High specific capacity, and at a current density of 1000 mAg -1 At that time, W 0.05 V 0.95 The S4 magnesium-ion battery cathode material maintained 95% capacity retention after 1500 cycles, demonstrating excellent cycle stability. Figure 6 ).

Claims

1. A magnesium-ion battery cathode material W doped with W to induce multi-electron reactions 0.05 V 0.95 S4, characterized in that, The preparation process is as follows: Ammonium tungstate and ammonium metavanadate were mixed at a molar ratio of 0.5% and dissolved in water under magnetic stirring at 60°C to prepare an aqueous solution of ammonium metavanadate with a concentration of 0.167M. Excess thioacetamide was dissolved in an equal volume of ethylene glycol. The two solutions were then completely mixed and transferred to a reaction vessel, where they were reacted at 200°C for 4 hours. After the reaction was complete, the mixture was washed three times with deionized water and three times with anhydrous ethanol, and then vacuum dried to obtain W-doped magnesium-ion battery cathode material W0. 0.05 V 0.95 S4; The obtained magnesium-ion battery cathode material W 0.05 V 0.95 S4 was assembled into a coin-type magnesium-ion battery. The voltage window for electrochemical performance testing was 0.2–2.1 V, and the current density was 50 and 1000 mAg. -1 .

2. The W-doped magnesium-ion battery cathode material according to claim 1, which induces multi-electron reactions. 0.05 V 0.95 S4, characterized in that, W doping can induce multi-electron magnesium storage reactions and maintain the structural stability of the microspheres during magnesium storage by controlling the morphology of the flower-like microspheres.

3. The W-doped magnesium-ion battery cathode material according to claim 1, which induces multi-electron reactions. 0.05 V 0.95 S4, characterized in that, When the prepared material is used as the positive electrode of a magnesium-ion battery, at a current density of 50 mAg... -1 At that time, the specific capacity remained stable at 150mAh g. -1 At 1000mA g -1 At current density, W 0.05 V 0.95 After 1500 cycles, the S4 maintained a capacity retention of 95%.

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