A calcium-doped sodium vanadate electrode material, a preparation method thereof and application thereof in a water-based ammonium ion battery

Abstract

This invention belongs to the field of battery electrode material technology, and discloses a calcium-doped sodium vanadate electrode material, its preparation method, and its application in aqueous ammonium-ion batteries. The preparation method includes the following steps: vanadium pentoxide is dispersed in water, hydrogen peroxide is added and stirred, and calcium nitrate and sodium hydroxide are added. The resulting mixed solution is transferred to a reaction vessel for hydrothermal reaction. After cooling to room temperature, the sample is washed, freeze-dried, and collected. When the calcium-doped sodium vanadate cathode material is applied to an aqueous ammonium-ion battery, electrochemical test results show that when paired with a 3,4,9,10-perylenetetracarboxylate diimide anode, it exhibits high reversible specific capacity and excellent rate performance, demonstrating its outstanding comprehensive electrochemical performance and great potential in practical energy storage applications. This invention features a simple synthesis route, is environmentally friendly, has low raw material costs, and the overall process has industrial application potential, making it suitable for promotion and application as a novel energy storage device.

Description

Technical Field

[0001] This invention belongs to the field of battery electrode material technology, and specifically relates to a calcium-doped sodium vanadate electrode material, its preparation method, and its application in aqueous ammonium-ion batteries. Background Technology

[0002] With the global energy structure shifting towards cleaner and lower-carbon energy sources, and the large-scale grid connection of renewable energy sources such as wind and solar power, there is an urgent need for efficient, safe, and low-cost energy storage technologies. While lithium-ion batteries have become the mainstream energy storage technology, they suffer from limited resource reserves and the flammability and explosiveness of organic electrolytes. Against this backdrop, aqueous batteries, with their non-flammable aqueous electrolytes, high ionic conductivity, mild manufacturing processes, and environmental friendliness, are gradually becoming an important research direction for next-generation energy storage systems.

[0003] In the exploration of diverse technological routes for aqueous batteries, aqueous ammonium-ion batteries, with their unique ion transport and electrode compatibility characteristics, have emerged as a highly promising new branch, further expanding the application boundaries of aqueous energy storage. Ammonium ions, as charge carriers, possess high compatibility with water, a moderate ionic radius, and excellent diffusion kinetics. They can achieve rapid and reversible intercalation / deintercalation reactions in various electrode materials, including layered oxides, Prussian blue compounds, and organic conjugated polymers. Simultaneously, ammonium salt raw materials are abundant, inexpensive, and non-toxic, reducing battery manufacturing costs and environmental risks from the outset, perfectly meeting the core demands of large-scale energy storage for "low cost, high safety, and long lifespan." Aqueous ammonium-ion batteries not only retain the inherent advantages of aqueous electrolytes—non-flammability and no risk of thermal runaway—but also achieve optimizations in electrode stability, ion transport efficiency, and overall life-cycle economics. They provide new insights into solving key challenges in current aqueous energy storage systems, such as side reaction suppression, cycle life improvement, and cost control, and are gradually becoming a research hotspot and industrialization exploration direction in the field of aqueous energy storage.

[0004] Therefore, in this invention, we rationally designed and synthesized a calcium-doped sodium vanadate electrode material, and constructed an aqueous ammonium-ion battery based on it. This system exhibits excellent electrochemical performance, providing a feasible strategy for further research and practical application of aqueous ammonium-ion batteries, and has good application prospects in the field of novel energy storage devices. Summary of the Invention

[0005] The present invention aims to prepare a calcium-doped sodium vanadate material and explore its application potential in aqueous ammonium-ion batteries. The results show that the aqueous ammonium-ion battery constructed based on the calcium-doped sodium vanadate electrode has excellent electrochemical performance.

[0006] The technical solution adopted in this invention is: a method for preparing calcium-doped sodium vanadate electrode material, comprising the following steps: dispersing vanadium pentoxide in deionized water, adding hydrogen peroxide solution, stirring, adding sodium hydroxide and calcium nitrate, stirring, transferring the resulting uniform mixed solution into a reaction vessel, carrying out a hydrothermal reaction, cooling to room temperature, washing, freeze-drying, and collecting the final sample, which is calcium-doped sodium vanadate material.

[0007] The above-mentioned method for preparing a calcium-doped sodium vanadate electrode material uses a molar ratio of vanadium pentoxide: sodium hydroxide: calcium nitrate = 6:4:1~4.

[0008] In the above-mentioned method for preparing a calcium-doped sodium vanadate electrode material, the concentration of the hydrogen peroxide solution is 30%.

[0009] The above-mentioned method for preparing a calcium-doped sodium vanadate electrode material, wherein the calcium nitrate is Ca(NO3)2·4H2O.

[0010] The above-mentioned method for preparing a calcium-doped sodium vanadate electrode material, wherein the hydrothermal reaction conditions are 180 °C for 32 h.

[0011] The calcium-doped sodium vanadate electrode material prepared by the above preparation method.

[0012] The above-mentioned calcium-doped sodium vanadate electrode material is used as a positive electrode material in aqueous ammonium-ion batteries.

[0013] The above-mentioned application, a method for preparing an aqueous ammonium-ion battery using calcium-doped sodium vanadate electrode material as the positive electrode material, includes the following steps:

[0014] Step 1: Preparation of positive electrode: Mix calcium-doped sodium vanadate electrode material, conductive agent and binder in proportion, add NMP solvent, grind evenly, coat directly on carbon paper, and dry to obtain positive electrode sheet coated with calcium-doped sodium vanadate.

[0015] Preparation of negative electrode: 3,4,9,10-perylenetetracarboxylic acid diimide material, conductive agent and binder are mixed evenly in proportion, NMP solvent is added dropwise, ground evenly, directly coated on carbon paper, and dried to obtain a negative electrode sheet coated with 3,4,9,10-perylenetetracarboxylic acid diimide.

[0016] Step 2: Preparation of the aqueous ammonium-ion battery: Cut the positive electrode coated with calcium-doped sodium vanadate and the negative electrode coated with 3,4,9,10-perylenetetracarboxylate diimide to a fixed size. Place the prepared negative electrode in the center of the negative electrode shell with the side coated with 3,4,9,10-perylenetetracarboxylate diimide facing upwards. Then place the separator and add electrolyte. Next, place the positive electrode on top of the separator with the side coated with calcium-doped sodium vanadate in contact with the separator. Then place the gasket and spring in sequence, adjust the position of each component to make them centered and aligned, and finally cover the positive electrode shell and press it to seal to obtain a button-type aqueous ammonium-ion battery.

[0017] In the above application, in step 1, the adhesive is PVDF or CMC, and the conductive agent is Super P or acetylene black.

[0018] In the above application, step 2, the electrolyte is an ammonium acetate solution with added sodium acetate or an ammonium sulfate solution with added sodium sulfate; the diaphragm is one of glass fiber, filter paper, or a polymer semi-permeable membrane.

[0019] The beneficial effects of this invention are:

[0020] 1. This invention synthesizes a calcium-doped sodium vanadate electrode material using a one-step hydrothermal method. Calcium ions effectively widen the interlayer spacing, which is beneficial for ion insertion / extraction. The synthesis process is simple and easy to implement, the raw materials are readily available and inexpensive, the production process is highly controllable and the preparation is easy, while the reaction conditions are mild and environmentally friendly, in line with the development concept of green synthesis.

[0021] 2. This invention designs an aqueous ammonium-ion battery based on calcium-doped sodium vanadate electrode material. The aqueous electrolyte used has the significant advantages of being non-toxic, harmless, and highly safe. It not only uses economical raw materials and produces no pollutants during use, exhibiting excellent environmental compatibility, but also has a simple preparation and usage process, facilitating large-scale industrial production. The addition of electrolyte additives helps suppress the release of sodium ions between the vanadium and oxygen layers.

[0022] 3. This invention discloses an aqueous ammonium-ion battery based on calcium-doped sodium vanadate cathode material with excellent electrochemical performance. At a current density of 0.2 A / g, the specific capacity can reach 54.09 mAh / g, and the coulombic efficiency is close to 100%. The capacity remains stable at various current densities, and even with a tenfold increase in current density (0.1→1 A / g), the capacity retention exceeds 60%. Attached Figure Description

[0023] Figure 1 This is the XRD pattern of the calcium-doped sodium vanadate material prepared in Example 1.

[0024] Figure 2This is the SEM spectrum of the calcium-doped sodium vanadate material prepared in Example 1.

[0025] Figure 3 This is a specific capacity diagram of the aqueous ammonium-ion battery based on calcium-doped sodium vanadate cathode material prepared in Example 6.

[0026] Figure 4 This is a rate curve of the aqueous ammonium-ion battery based on calcium-doped sodium vanadate cathode material prepared in Example 6. Detailed Implementation

[0027] The technical solution of the present invention will be further described below, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention that do not depart from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0028] Example 1

[0029] (I) Calcium-doped sodium vanadate material, prepared by the following method:

[0030] Weigh 6 mmol of vanadium pentoxide and disperse it in 60 mL of deionized water. Then add 5 mL of 30% hydrogen peroxide solution and stir magnetically for 30 min. Next, add 2 mmol of calcium nitrate and 4 mmol of sodium hydroxide, and continue stirring for another 30 min to ensure thorough mixing. Transfer the resulting homogeneous solution to a reaction vessel and react at 180 °C for 32 h. After cooling to room temperature, collect the product, filter it, and wash with ethanol and deionized water to remove impurities. After filtration, freeze-dry for 12 h and collect the final sample to obtain the calcium-doped sodium vanadate material.

[0031] (II) Testing

[0032] Figure 1 This is the XRD pattern of the calcium-doped sodium vanadate (CaNaVO) material prepared in Example 1. Figure 1 As can be seen, by comparing with the card (JCPDS: 00-016-0601), the XRD spectrum of the sample after calcium ion doping did not show significant changes compared with the sodium vanadate material, with only a shift of a few peaks, proving that calcium ions were successfully doped into sodium vanadate.

[0033] Figure 2 This is a SEM image of the calcium-doped sodium vanadate material prepared in Example 1. (The image is derived from...) Figure 2 It is evident that sodium vanadate materials doped with calcium ions still exhibit a nanoribbon structure.

[0034] Example 2

[0035] The preparation method of calcium-doped sodium vanadate material is as follows:

[0036] Weigh 6 mmol of vanadium pentoxide and disperse it in 60 mL of deionized water. Then add 5 mL of 30% hydrogen peroxide solution and stir magnetically for 30 min. Next, add 1 mmol of calcium nitrate and 4 mmol of sodium hydroxide, and continue stirring for another 30 min to ensure thorough mixing. Transfer the resulting homogeneous solution to a reaction vessel and react at 180 °C for 32 h. After cooling to room temperature, collect the product, filter it, and wash with ethanol and deionized water to remove impurities. After filtration, freeze-dry for 12 h and collect the final sample to obtain the calcium-doped sodium vanadate material.

[0037] Example 3

[0038] The preparation method of calcium-doped sodium vanadate material is as follows:

[0039] Weigh 6 mmol of vanadium pentoxide and disperse it in 60 mL of deionized water. Then add 5 mL of 30% hydrogen peroxide solution and stir magnetically for 30 min. Next, add 3 mmol of calcium nitrate and 4 mmol of sodium hydroxide, and continue stirring for another 30 min to ensure thorough mixing. Transfer the resulting homogeneous solution to a reaction vessel and react at 180 °C for 32 h. After cooling to room temperature, collect the product, filter it, and wash with ethanol and deionized water to remove impurities. After filtration, freeze-dry for 12 h and collect the final sample to obtain the calcium-doped sodium vanadate material.

[0040] Example 4

[0041] The preparation method of calcium-doped sodium vanadate material is as follows:

[0042] Weigh 6 mmol of vanadium pentoxide and disperse it in 60 mL of deionized water. Then add 5 mL of 30% hydrogen peroxide solution and stir magnetically for 30 min. Next, add 4 mmol of calcium nitrate and 4 mmol of sodium hydroxide, and continue stirring for another 30 min to ensure thorough mixing. Transfer the resulting homogeneous solution to a reaction vessel and react at 180 °C for 32 h. After cooling to room temperature, collect the product, filter it, and wash with ethanol and deionized water to remove impurities. After filtration, freeze-dry for 12 h and collect the final sample to obtain the calcium-doped sodium vanadate material.

[0043] Example 5

[0044] The negative electrode sheet using 3,4,9,10-perylenetetracarboxylate diimide as the active material is prepared as follows:

[0045] 80 mg of 3,4,9,10-perylenetetracarboxylic acid diimide, 10 mg of conductive agent Super P, and 10 mg of binder PVDF were added to a mortar, and a small amount of NMP was added as a solvent to ensure full contact of the materials. The mixture was ground for 40 min to obtain a uniformly ground slurry. The slurry was then directly coated onto a substrate carbon paper. The slurry was placed in a vacuum drying oven and dried at 60 °C for 12 h. After drying, the slurry was removed, punched, and a negative electrode sheet coated with 3,4,9,10-perylenetetracarboxylic acid diimide was obtained.

[0046] Example 6

[0047] An aqueous ammonium-ion battery based on calcium-doped sodium vanadate cathode material is prepared by the following method:

[0048] (1) Preparation of the positive electrode: 80 mg of the calcium-doped sodium vanadate material obtained in Example 1, 10 mg of conductive agent Super P and 10 mg of binder PVDF were added to a mortar, and a small amount of NMP solvent was added dropwise to ensure full contact of the materials. The mixture was ground for 40 min to obtain a uniformly ground slurry. The slurry was then directly and uniformly coated onto a substrate carbon paper. The paper was placed in a vacuum drying oven and dried at 60 °C for 12 h. After drying, the paper was punched to obtain a positive electrode sheet coated with the calcium-doped sodium vanadate material.

[0049] (2) Preparation of aqueous ammonium-ion battery: The electrode prepared using the calcium-doped sodium vanadate material obtained in Example 1 as the active material is the positive electrode, and the electrode prepared using 3,4,9,10-perylenetetracarboxylate diimide obtained in Example 5 as the active material is the negative electrode. First, the negative electrode prepared in Example 5 is placed in the center of the negative electrode shell, with the side coated with 3,4,9,10-perylenetetracarboxylate diimide material facing upward. Then, the separator is placed in, and 180 μL of ammonium sulfate electrolyte with a concentration of 1 M containing 0.01 M sodium sulfate is slowly dripped in. Then, the positive electrode is placed on top of the separator, with the side coated with calcium-doped sodium vanadate material in contact with the separator. Then, the gasket and spring are placed in sequence, and the positions of each component are adjusted to be centered and aligned. Finally, the positive electrode shell is closed, and the whole assembly is uniformly pressed and sealed using a button battery sealing machine. The assembly of a complete button-type aqueous ammonium-ion battery based on calcium-doped sodium vanadate positive electrode material is completed.

[0050] Example 7

[0051] An aqueous ammonium-ion battery based on calcium-doped sodium vanadate cathode material is prepared by the following method:

[0052] (1) Preparation of the positive electrode: 80 mg of the calcium-doped sodium vanadate material obtained in Example 2, 10 mg of conductive agent Super P and 10 mg of binder PVDF were added to a mortar, and a small amount of NMP solvent was added dropwise to ensure full contact of the materials. The mixture was ground for 40 min to obtain a uniformly ground slurry. The slurry was then directly and uniformly coated onto a substrate carbon paper. The paper was placed in a vacuum drying oven and dried at 60 °C for 12 h. After drying, the paper was punched to obtain a positive electrode sheet coated with the calcium-doped sodium vanadate material.

[0053] (2) Preparation of aqueous ammonium-ion battery: The electrode prepared using the calcium-doped sodium vanadate material obtained in Example 2 as the active material is the positive electrode, and the electrode prepared using 3,4,9,10-perylenetetracarboxylate diimide obtained in Example 5 as the active material is the negative electrode. First, the negative electrode prepared in Example 5 is placed in the center of the negative electrode shell, with the side coated with 3,4,9,10-perylenetetracarboxylate diimide material facing upward. Then, the separator is placed in, and 180 μL of ammonium sulfate electrolyte with a concentration of 1 M containing 0.01 M sodium sulfate is slowly dripped in. Then, the positive electrode is placed on top of the separator, with the side coated with calcium-doped sodium vanadate material in contact with the separator. Then, the gasket and spring are placed in sequence, and the positions of each component are adjusted to be centered and aligned. Finally, the positive electrode shell is closed, and the whole assembly is uniformly pressed and sealed using a button battery sealing machine. The assembly of a complete button-type aqueous ammonium-ion battery based on calcium-doped sodium vanadate positive electrode material is completed.

[0054] Example 8

[0055] An aqueous ammonium-ion battery based on calcium-doped sodium vanadate cathode material is prepared by the following method:

[0056] (1) Preparation of the positive electrode: 80 mg of the calcium-doped sodium vanadate material obtained in Example 3, 10 mg of conductive agent Super P and 10 mg of binder PVDF were added to a mortar, and a small amount of NMP solvent was added dropwise to ensure full contact of the materials. The mixture was ground for 40 min to obtain a uniformly ground slurry. The slurry was then directly and uniformly coated onto a substrate carbon paper. The paper was placed in a vacuum drying oven and dried at 60 °C for 12 h. After drying, the paper was punched to obtain a positive electrode sheet coated with the calcium-doped sodium vanadate material.

[0057] (2) Preparation of aqueous ammonium-ion battery: The electrode prepared using the calcium-doped sodium vanadate material obtained in Example 3 as the active material is the positive electrode, and the electrode prepared using 3,4,9,10-perylenetetracarboxylate diimide obtained in Example 5 as the active material is the negative electrode. First, the negative electrode prepared in Example 5 is placed in the center of the negative electrode shell, with the side coated with 3,4,9,10-perylenetetracarboxylate diimide material facing upward. Then, the separator is placed in, and 180 μL of ammonium sulfate electrolyte with a concentration of 1 M containing 0.01 M sodium sulfate is slowly dripped in. Then, the positive electrode is placed on top of the separator, with the side coated with calcium-doped sodium vanadate material in contact with the separator. Then, the gasket and spring are placed in sequence, and the positions of each component are adjusted to be centered and aligned. Finally, the positive electrode shell is closed, and the whole assembly is uniformly pressed and sealed using a button battery sealing machine. The assembly of a complete button-type aqueous ammonium-ion battery based on calcium-doped sodium vanadate positive electrode material is completed.

[0058] Example 9

[0059] An aqueous ammonium-ion battery based on calcium-doped sodium vanadate cathode material is prepared by the following method:

[0060] (1) Preparation of the positive electrode: 80 mg of the calcium-doped sodium vanadate material obtained in Example 4, 10 mg of conductive agent Super P and 10 mg of binder PVDF were added to a mortar, and a small amount of NMP solvent was added dropwise to ensure full contact of the materials. The mixture was ground for 40 min to obtain a uniformly ground slurry. The slurry was then directly and uniformly coated onto a substrate carbon paper. The paper was placed in a vacuum drying oven and dried at 60 °C for 12 h. After drying, the paper was punched to obtain a positive electrode sheet coated with the calcium-doped sodium vanadate material.

[0061] (2) Preparation of aqueous ammonium-ion battery: The electrode prepared using the calcium-doped sodium vanadate material obtained in Example 4 as the active material is the positive electrode, and the electrode prepared using 3,4,9,10-perylenetetracarboxylate diimide obtained in Example 5 as the active material is the negative electrode. First, the negative electrode prepared in Example 5 is placed in the center of the negative electrode shell, with the side coated with 3,4,9,10-perylenetetracarboxylate diimide material facing upward. Then, the separator is placed in, and 180 μL of ammonium sulfate electrolyte with a concentration of 1 M containing 0.01 M sodium sulfate is slowly dripped in. Then, the positive electrode is placed on top of the separator, with the side coated with calcium-doped sodium vanadate material in contact with the separator. Then, the gasket and spring are placed in sequence, and the positions of each component are adjusted to be centered and aligned. Finally, the positive electrode shell is closed, and the whole assembly is uniformly pressed and sealed using a button battery sealing machine. The assembly of a complete button-type aqueous ammonium-ion battery based on calcium-doped sodium vanadate positive electrode material is completed.

[0062] Of the four aqueous ammonium-ion batteries assembled according to Examples 6-9 above, Example 6 exhibits the best electrochemical performance. Figure 3This is the specific capacity diagram of the aqueous ammonium-ion battery based on calcium-doped sodium vanadate cathode material prepared in Example 6 at a current density of 0.2 A / g. At a current density of 0.2 A / g and a voltage window of 0~1.6 V, the discharge specific capacity is approximately 54.09 mAh / g, and the coulombic efficiency is close to 100%. Figure 4 This is a rate performance diagram of the aqueous ammonium-ion battery based on a calcium-doped sodium vanadate cathode prepared in Example 6, at current densities of 0.1–1 A / g. (From...) Figure 4 As can be seen, the specific capacity of the aqueous ammonium-ion battery based on calcium-doped sodium vanadate cathode material prepared in Example 6 is stable at various current densities. As the current density increases from 0.1 A / g to 1 A / g, the capacity retention exceeds 60%, maintaining a stable discharge capacity even at high currents. This indicates that the full cell possesses rapid ion / electron transport capabilities and excellent rate performance. After the current returns to 0.1 A / g, the capacity is almost completely recovered, demonstrating that the full cell maintains structural integrity during high-current cycling, exhibits excellent electrochemical reversibility, and shows promising development prospects.

Claims

1. A method for preparing a calcium-doped sodium vanadate electrode material, characterized in that, The process includes the following steps: Vanadium pentoxide is dispersed in deionized water, hydrogen peroxide solution is added, and after stirring, sodium hydroxide and calcium nitrate are added and stirred. The resulting homogeneous mixed solution is transferred into a reaction vessel for hydrothermal reaction, cooled to room temperature, washed, freeze-dried, and the final sample is collected, which is a calcium-doped sodium vanadate material.

2. The method for preparing a calcium-doped sodium vanadate electrode material according to claim 1, characterized in that, The molar ratio of vanadium pentoxide : sodium hydroxide : calcium nitrate is 6 : 4 : 1~4.

3. The method for preparing a calcium-doped sodium vanadate electrode material according to claim 1, characterized in that, The concentration of the hydrogen peroxide solution is 30%.

4. The method for preparing a calcium-doped sodium vanadate electrode material according to claim 1, characterized in that, The calcium nitrate is Ca(NO3)2·4H2O.

5. The method for preparing a calcium-doped sodium vanadate electrode material according to claim 1, characterized in that, The hydrothermal reaction conditions are: reaction at 180 °C for 32 h.

6. The calcium-doped sodium vanadate electrode material prepared according to any one of claims 1-5.

7. The application of the calcium-doped sodium vanadate electrode material according to claim 6 as a positive electrode material in an aqueous ammonium-ion battery.

8. The application according to claim 7, characterized in that, A method for preparing an aqueous ammonium-ion battery using calcium-doped sodium vanadate electrode material as the positive electrode material includes the following steps. Step 1: Preparation of positive electrode: Mix calcium-doped sodium vanadate electrode material, conductive agent and binder in proportion, add NMP solvent, grind evenly, coat directly on carbon paper, and dry to obtain positive electrode sheet coated with calcium-doped sodium vanadate. Preparation of negative electrode: 3,4,9,10-perylenetetracarboxylic acid diimide material, conductive agent and binder are mixed evenly in proportion, NMP solvent is added dropwise, ground evenly, directly coated on carbon paper, and dried to obtain a negative electrode sheet coated with 3,4,9,10-perylenetetracarboxylic acid diimide. Step 2: Preparation of the aqueous ammonium-ion battery: Cut the positive electrode coated with calcium-doped sodium vanadate and the negative electrode coated with 3,4,9,10-perylenetetracarboxylate diimide to a fixed size. Place the prepared negative electrode in the center of the negative electrode shell with the side coated with 3,4,9,10-perylenetetracarboxylate diimide facing upwards. Then place the separator and add electrolyte. Next, place the positive electrode on top of the separator with the side coated with calcium-doped sodium vanadate in contact with the separator. Then place the gasket and spring in sequence, adjust the position of each component to make them centered and aligned, and finally cover the positive electrode shell and press it to seal to obtain a button-type aqueous ammonium-ion battery.

9. The application according to claim 8, characterized in that, In step 1, the adhesive is PVDF or CMC, and the conductive agent is Super P or acetylene black.

10. The application according to claim 8, characterized in that, In step 2, the electrolyte is an ammonium acetate solution with added sodium acetate or an ammonium sulfate solution with added sodium sulfate; the diaphragm is one of glass fiber, filter paper or a polymer semi-permeable membrane.

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