Indium vanadate modified sodium metal negative electrode and preparation method and sodium battery

Abstract

This application belongs to the field of sodium battery technology, and particularly relates to an indium vanadate modified sodium metal anode, its preparation method, and a sodium battery. The indium vanadate modified sodium metal anode provided by this application provides abundant active sites for sodium ion deposition by pre-preparing an artificial Na-In-V-O compound interface layer on the surface of the sodium metal anode, which promotes uniform sodium ion deposition and greatly reduces the generation of sodium dendrites and "dead sodium". Furthermore, the preparation process of the indium vanadate modified sodium metal anode is simple and conducive to large-scale industrial production, thereby solving the technical problem in the prior art that sodium metal anodes are prone to uncontrollable sodium dendrite growth, leading to a decline in the cycle performance of sodium-ion batteries.

Description

Technical Field

[0001] This application belongs to the field of sodium battery technology, and particularly relates to an indium vanadate modified sodium metal anode, its preparation method, and a sodium battery. Background Technology

[0002] Lithium-ion batteries have advantages such as high specific energy and operating voltage, good cycle performance and environmental friendliness. They are currently widely used in new energy power plants, automobiles and small mobile devices. For example, new energy power generation equipment such as wind farms and solar power plants are usually equipped with corresponding energy storage devices to improve energy utilization efficiency. New energy vehicles use lithium-ion batteries to replace internal combustion engines as a power source, and portable mobile devices also use lithium batteries as an energy source. However, the scarcity and uneven distribution of lithium resources have restricted the further development and application of lithium-ion batteries.

[0003] Compared to lithium, sodium is more abundant, and sodium-ion batteries share similar electrochemical properties with lithium-ion batteries, operating on the "rocking chair battery" principle, making them a promising alternative to lithium-ion batteries. The structure of sodium-ion batteries is similar to that of lithium-ion batteries, also including a negative electrode. Negative electrode materials for sodium-ion batteries include carbon-based materials, alloys, metal oxides, and sulfides. Among these negative electrode materials, sodium metal has a high theoretical specific capacity (approximately 1166 mAh g⁻¹). -1 Its low redox potential (approximately -2.71V, compared to the standard hydrogen electrode potential) makes it one of the most promising anode materials.

[0004] However, during the application of sodium metal anodes, an irreversible reaction occurs between the sodium metal anode and the organic electrolyte, spontaneously forming an SEI layer on the anode. The volume expansion of this in-situ formed SEI layer during the sodium ion insertion process leads to its destruction. Subsequently, cracks in the SEI layer become active sites for uncontrollable sodium dendrite formation, thereby severely reducing the electrochemical performance and safety of sodium metal batteries, and causing a rapid decline in the cycle performance of sodium-ion batteries. Summary of the Invention

[0005] In view of this, this application provides an indium vanadate modified sodium metal anode, a preparation method thereof, and a sodium battery, to solve the technical problem that uncontrollable sodium dendrite growth easily occurs in sodium metal anodes in the prior art, leading to a decrease in the cycle performance of sodium-ion batteries.

[0006] The first aspect of this application provides an indium vanadate modified sodium metal anode, comprising a sodium metal anode and a Na-In-VO compound interface layer;

[0007] The Na-In-VO compound interface layer coats the surface of the sodium metal anode.

[0008] Preferably, the thickness of the indium vanadate modified sodium metal anode is 100-200 micrometers.

[0009] The second aspect of this application provides a method for preparing an indium vanadate-modified sodium metal anode, the method comprising the following steps:

[0010] Step S1: In a glove box, the sodium metal block is made into a thin sheet to obtain a sodium metal negative electrode;

[0011] Step S2: Coat the sodium metal anode surface with indium vanadate powder and react to obtain indium vanadate modified sodium metal anode.

[0012] Preferably, in step S1, the protective gas in the glove box is argon, nitrogen, or helium.

[0013] Preferably, in step S2, the reaction time is 12 to 24 hours.

[0014] Preferably, in step S2, the method for preparing the indium vanadate powder includes: grinding indium vanadate in a mortar and then vacuum drying to obtain indium vanadate powder.

[0015] Preferably, the grinding time is 30 to 60 minutes;

[0016] The vacuum drying temperature is 60–80 degrees Celsius, and the time is 8–16 hours.

[0017] A third aspect of this application provides a sodium battery, including an electrolyte, a separator, a positive electrode, and the aforementioned indium vanadate-modified sodium metal negative electrode.

[0018] Preferably, the sodium salt in the electrolyte is sodium perchlorate, the solvent is a mixture of ethylene carbonate and diethyl carbonate, and the additive is fluoroethylene carbonate.

[0019] Preferably, the volume ratio of ethylene carbonate to diethyl carbonate in the electrolyte is 1:1 to 3;

[0020] The mass fraction of the fluoroethylene carbonate is 3-10 wt%.

[0021] The concentration of sodium perchlorate is 0.5–3 mol / L.

[0022] Preferably, the diaphragm is selected from Celgard 3501 diaphragm or Whatman glass fiber.

[0023] Preferably, the positive electrode is selected from Prussian blue compounds or Prussian white compounds.

[0024] In summary, this application provides an indium vanadate-modified sodium metal anode, its preparation method, and a sodium battery. The indium vanadate-modified sodium metal anode includes a sodium metal anode and a Na-In-VO compound interface layer on its surface. The Na-In-VO compound interface layer, as a pre-prepared artificial interface layer, introduces two metal elements, In and V, which can provide abundant active sites for sodium ion deposition, thereby regulating the deposition behavior of sodium ions, promoting uniform sodium ion deposition, alleviating the phenomenon of local enrichment of sodium ions, and greatly reducing the generation of sodium dendrites and "dead sodium". This solves the technical problem in the prior art that sodium metal anodes are prone to uncontrollable sodium dendrite growth, leading to a decline in the cycle performance of sodium-ion batteries. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 X-ray diffraction pattern of indium vanadate modified sodium metal anode prepared by the preparation method provided in the embodiments of this application;

[0027] Figure 2 Scanning electron microscope image and elemental distribution map of the indium vanadate modified sodium metal anode prepared by the preparation method provided in the embodiments of this application;

[0028] Figure 3 Figure 1 shows the cycle performance test results of the sodium metal anode modified with indium vanadate and the sodium metal anode prepared by the preparation method provided in the embodiments of this application after being assembled into a sodium battery.

[0029] Figure 2 middle, Figure 2 Figure a shows a scanning electron microscope image of the sodium metal anode modified with indium vanadate. In the figure, Na, ln, V, and O are the elemental distribution diagrams of sodium, indium, vanadium, and oxygen on the sodium metal anode modified with indium vanadate, respectively. Detailed Implementation

[0030] This application provides an indium vanadate-modified sodium metal anode, its preparation method, and a sodium battery, which solves the technical problem that uncontrollable sodium dendrite growth easily occurs in sodium metal anodes in the prior art, leading to a decrease in the cycle performance of sodium-ion batteries.

[0031] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0032] Example 1

[0033] Given that the sodium metal anode used in existing sodium batteries is prone to uncontrolled sodium dendrite growth, resulting in poor cycle performance, Example 1 of this application provides an indium vanadate-modified sodium metal anode; a sodium metal anode and a Na-In-VO compound interface layer, with the Na-In-VO compound interface layer covering the surface of the sodium metal anode; the in-situ interface layer spontaneously formed by the sodium metal anode in the electrolyte has poor performance. By pretreating the sodium metal anode to form an artificial Na-In-VO compound interface layer, the defects of the in-situ interface layer can be overcome. The artificial Na-In-VO compound interface layer covers the surface of the sodium metal anode and introduces two metal elements, In and V, which can provide abundant active sites for sodium ion deposition, thereby regulating the deposition behavior of sodium ions, promoting uniform sodium ion deposition, alleviating the phenomenon of local sodium ion enrichment, and greatly reducing the generation of sodium dendrites and "dead sodium". At the same time, the artificial Na-In-VO compound interface layer has excellent mechanical properties and is not prone to cracking, thus overcoming the defect of uncontrolled sodium dendrite growth in the sodium metal anode, resulting in poor cycle performance.

[0034] For the size of the sodium metal anode, it is preferred to have a size of 100 to 200 micrometers. For the shape of the sodium metal anode, it is preferred to have a disc shape.

[0035] Example 2

[0036] Example 2 of this application provides a method for preparing the indium vanadate modified sodium metal anode described in the example. The preparation method includes a grinding step of indium vanadate powder and a modification step of sodium metal anode.

[0037] The grinding steps of indium vanadate powder include: weighing 40 mg of indium vanadate powder, grinding the indium vanadate powder carefully for 30 min, and then drying it in a vacuum drying oven to obtain dry indium vanadate powder with a particle size of about 20-50 nm.

[0038] The modification steps for the sodium metal anode include: rolling out a sodium metal block into a 40 cm² area in a glove box. 2 A thin sheet with a thickness of 150 μm was prepared by uniformly coating a sodium metal surface with dry indium vanadate powder, with an indium vanadate loading of 1 mg / cm³. -2The mixture was then placed in a glove box and allowed to react for 12 hours. After the indium vanadate and sodium metal anode reacted, an amorphous artificial Na-In-VO compound interface layer was formed. The protective gas in the glove box was argon, and the contents of water and oxygen were both less than 0.01 ppm.

[0039] It should be noted that, as can be seen from the above preparation steps, the preparation method of the indium vanadate modified sodium metal anode provided in this application can be obtained simply by uniformly coating indium vanadate powder onto the sodium metal surface through a simple physical coating reaction. The process is simple and conducive to large-scale industrial production.

[0040] Example 3

[0041] Example 3 of this application provides a method for preparing the indium vanadate modified sodium metal anode described in the example. The preparation method includes a grinding step of indium vanadate powder and a modification step of the sodium metal anode.

[0042] The grinding steps of indium vanadate powder include: weighing 80mg of indium vanadate powder, grinding the indium vanadate powder carefully for 30min, and then drying it in a vacuum drying oven to obtain dry indium vanadate powder with a particle size of about 20-50nm.

[0043] The modification steps for the sodium metal anode include: rolling out a sodium metal block into a 40 cm² area in a glove box. 2 A thin sheet with a thickness of 150 μm was prepared by uniformly coating a sodium metal surface with dry indium vanadate powder, with an indium vanadate loading of 2 mg / cm³. -2 The mixture was then placed in a glove box and allowed to react for 12 hours. After the indium vanadate and sodium metal anode reacted, an amorphous artificial Na-In-VO compound interface layer was formed. The protective gas in the glove box was argon, and the contents of water and oxygen were both less than 1 ppm.

[0044] Example 4

[0045] Example 4 of this application provides a method for preparing the indium vanadate modified sodium metal anode described in the example. The preparation method includes a grinding step of indium vanadate powder and a modification step of the sodium metal anode.

[0046] The grinding steps of indium vanadate powder include: weighing 20mg of indium vanadate powder, grinding the indium vanadate powder carefully for 30min, and then drying it in a vacuum drying oven to obtain dry indium vanadate powder with a particle size of about 20-50nm.

[0047] The modification steps for the sodium metal anode include: rolling out a sodium metal block into a 40 cm² area in a glove box. 2 A thin sheet with a thickness of 150 μm was prepared by uniformly coating a sodium metal surface with dry indium vanadate powder, with an indium vanadate loading of 0.5 mg / cm³. -2The mixture was then placed in a glove box and allowed to react for 12 hours. After the indium vanadate and sodium metal anode reacted, an amorphous artificial Na-In-VO compound interface layer was formed. The protective gas in the glove box was argon, and the contents of water and oxygen were both less than 1 ppm.

[0048] Experimental Example 1

[0049] Example 1 of this experiment tested the structure and performance of the indium vanadate modified sodium metal anode prepared in Example 1. The structural tests included X-ray diffraction, scanning electron microscopy, and elemental analysis, while the performance tests included cycle performance testing.

[0050] Among them, X-ray diffraction testing, such as Figure 1 As shown, scanning electron microscopy analysis and elemental analysis are as follows: Figure 2 As shown; from Figure 1-2 It can be seen that after modifying the sodium metal anode with indium vanadate powder, no diffraction peaks of indium vanadate appeared on the surface of the indium vanadate-modified sodium metal anode. This indicates that after the indium vanadate powder is coated on the surface of the sodium metal anode, indium vanadate reacts with sodium to form a new compound. Further scanning electron microscopy and elemental analysis of the indium vanadate-modified sodium metal anode show that the elemental distribution on the surface of the indium vanadate-modified sodium metal anode is that Na, In, V, and O elements are uniformly distributed on the sodium metal surface. This indicates that the new compound formed by the reaction of indium vanadate and sodium is an amorphous Na-In-VO compound interface layer.

[0051] Cyclic performance testing was conducted on the indium vanadate-modified sodium metal anode and sodium metal anode prepared in Example 1. The indium vanadate-modified sodium metal anode and sodium metal anode were assembled into two coin cells respectively in an argon-atmosphere glove box. A constant current charge-discharge test was performed using a Newway battery testing system with a current density of 0.5 mA / cm². -2 The surface capacity is 1mAh cm -2 The cycle stability during the charge and discharge process was tested.

[0052] Performance test results are as follows Figure 3 As shown, from Figure 3 It can be seen that the overpotential of a coin cell assembled with a conventional sodium metal anode is about 150mV and the cycle life is about 180h. Compared with the coin cell assembled with a conventional sodium metal anode, the indium vanadate modified sodium metal anode prepared by the preparation method provided in Example 1 of this application, after being assembled into a coin cell, has an overpotential of about 30mV and a cycle life of more than 800h. This shows that the indium vanadate modified sodium metal anode provided in this application provides abundant active sites for sodium ion deposition through the pre-formed artificial Na-In-VO compound interface layer, regulates the deposition behavior of sodium ions, promotes uniform deposition of sodium ions, and overcomes the defect of poor performance of the interface layer formed in situ in ordinary sodium metal batteries.

[0053] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. An indium vanadate-modified sodium metal anode, characterized in that, Including the sodium metal anode and the Na-In-VO compound interface layer; The Na-In-VO compound interface layer coats the surface of the sodium metal anode. The preparation method of the indium vanadate modified sodium metal anode includes the following steps: Step S1: In a glove box, the sodium metal block is made into a thin sheet to obtain a sodium metal negative electrode; Step S2: Coat the sodium metal anode surface with indium vanadate powder and react to obtain indium vanadate modified sodium metal anode.

2. The indium vanadate-modified sodium metal anode according to claim 1, characterized in that, The thickness of the indium vanadate modified sodium metal anode is 100~200 micrometers.

3. The indium vanadate-modified sodium metal anode according to claim 1, characterized in that, In step S1, the protective gas in the glove box is argon, nitrogen, or helium.

4. The indium vanadate-modified sodium metal anode according to claim 1, characterized in that, In step S2, the reaction time is 12 to 24 hours.

5. The indium vanadate-modified sodium metal anode according to claim 1, characterized in that, In step S2, the amount of indium vanadate powder used for coating is 0.5~2 mg / cm². 2 .

6. The indium vanadate-modified sodium metal anode according to claim 1, characterized in that, In step S2, the preparation method of the indium vanadate powder includes: grinding indium vanadate in a mortar and then vacuum drying to obtain indium vanadate powder; The grinding time is 30-60 minutes; The vacuum drying temperature is 60-80 degrees Celsius, and the time is 8-16 hours.

7. A sodium battery, characterized in that, It includes an electrolyte, a separator, a positive electrode, and the indium vanadate modified sodium metal negative electrode as described in claim 1.

8. A sodium battery according to claim 7, characterized in that, The sodium salt in the electrolyte is sodium perchlorate, the solvent is a mixture of ethylene carbonate and diethyl carbonate, and the additive is fluoroethylene carbonate.

9. A sodium battery according to claim 8, characterized in that, The volume ratio of ethylene carbonate to diethyl carbonate in the electrolyte is 1:1~3; The mass fraction of the fluoroethylene carbonate is 3-10 wt%; The concentration of sodium perchlorate is 0.5~3 mol / L.

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