CN113130903B - Aluminum oxide coated iron cyanamide material prepared by sol-gel method and preparation method and application thereof - Google Patents

Abstract

The invention discloses a method for preparing alumina-coated ferric cyanamide material by using a sol-gel method, comprising: step 1: weighing ammonium oxalate ferric salt and urea according to a mass ratio of 3:5, and mixing them to obtain A; Step 2: First raise the temperature to 160°C at a rate of 30°C/min, keep it warm for 1 hour, and then raise the rate to 600°C at a rate of 5°C/min to obtain product B; Step 3: Weigh the aluminum source and amphoteric surfactant Dissolve in deionized water to obtain a solution with a concentration of 0.0007-0.013mol/L, adjust the pH ≈ 8, add product B, stir, filter with suction to collect the powder, wash, dry, and sieve to obtain precursor C; steps Four: Sinter the precursor sample C, raise the temperature to 300-400°C at a heating rate of 5-10°C/min, and keep it warm for 0-60min to obtain the product; the raw materials required for the synthesis of this technology are cheap, and the synthesis process is simple and easy. Operation, the product is uniformly coated and has a stable structure, which greatly reduces the occurrence of side reactions during the reaction process, thereby improving the electrochemical performance of the battery.

Description

A kind of aluminum oxide-coated ferric cyanamide material prepared by sol-gel method and its preparation preparation methods and applications

technical field

The invention belongs to the technical field of composite materials and relates to the preparation of composite electrode materials, in particular to a preparation method and application of aluminum oxide-coated ferric cyanamide materials prepared by using a sol-gel method.

Background technique

Lithium-ion batteries are widely used in portable electronic devices and are favored due to their high energy and high power. However, due to the constraints of lithium resources, lithium-ion batteries have been unable to meet the needs of large-scale energy storage systems. In the foreseeable future, the high cost and limitation of lithium resources will hinder the further application of lithium-based batteries. Therefore, secondary metal-ion batteries based on low-cost and resource-abundant elements such as Na, Mg, Al, and K are being widely considered. Among these emerging battery technologies, potassium-ion batteries have great advantages as an ideal substitute for lithium-ion batteries, because potassium is not only a low-cost, non-toxic and resource-abundant element (the weight percent of potassium in the earth's crust is 2.4 %), and it has a low redox potential of −2.93 V compared with the standard hydrogen electrode as a potassium ion/potassium ion pair, thereby providing high operating voltage and high energy density for low-cost Li-ion batteries.

However, due to the large size of potassium ions, it is difficult to directly intercalate into many lithium-ion battery electrode materials to realize the process of electrochemical potassium storage, which greatly limits the application prospects of such batteries. Therefore, how to take into account the high potassium storage capacity and fast and stable charge and discharge of electrode materials for potassium-ion batteries has become a research hotspot for many scholars in recent years, while regulating the charge-discharge mechanism of potassium-ion batteries and exploring new material structure systems are considered. is the key to solving the above problems.

Due to its low and flat charge-discharge potential platform, highly reversible reaction characteristics, high electrochemical reactivity and large specific capacity, ferric cyanamide compound has become a very potential battery anode material. However, the high reactivity makes ferric cyanamide materials severely damaged when their structures are completely rearranged during the electrochemical reaction, resulting in poor cycle performance. At present, the stability of sodium storage has been successfully improved by in-situ construction of an anchor structure containing iron-carbon bonds between the surface of the carbon matrix and the iron-cyanamide polyhedron. However, the structural damage of ferric cyanamide is more serious when potassium ions with larger radius are intercalated than when sodium ions are intercalated, and the capacity fading is more severe. Therefore, on this basis, it is still necessary to take certain measures to stabilize the structure of ferric cyanamide to alleviate the volume expansion that occurs when potassium ions are intercalated and extracted, so that it can become an excellent anode material for potassium-ion batteries.

Alumina is an important metal oxide, which has a wide range of applications in catalysis, optics, and energy conversion and storage. The surface modification of alumina is to deal with different types of electrode materials, especially the invention improves the performance of ferric cyanamide. It is a very important step. The surface modification of ferric cyanamide by alumina can alleviate the side reaction of the electrolyte and improve the structure and cycle stability of ferric cyanamide.

Contents of the invention

In view of the deficiencies in the above-mentioned prior art, the object of the present invention is to provide a ferric cyanamide material coated with alumina by sol-gel method and its preparation method and application, which can significantly improve the structure and cycle stability of potassium ion batteries. performance.

In order to achieve the above object, the technical scheme adopted in the present invention is:

A preparation method utilizing a sol-gel method to prepare alumina-coated ferric cyanamide materials, comprising the following steps:

Step 1: Weigh ammonium oxalate ferric salt and urea according to the mass ratio of 3:5, grind them to make them fully mixed, and obtain mixture A;

Step 2: In an inert gas atmosphere, first raise the temperature to 160°C at a rate of 30°C/min, keep it warm for 1 hour, then raise the temperature to 600°C at a rate of 5°C/min, stop the program after heating, wait until the temperature drops to Take out under room temperature condition, obtain product B, be ferric cyanamide;

Step 3: Dissolve the aluminum source and amphoteric surfactant in deionized water at a mass ratio of 1:10 to 10:1, stir for 30 minutes to fully dissolve, and obtain a solution with an aluminum ion concentration of 0.0007 to 0.013 mol/L, and then Add ammonia water with a mass concentration of 15% drop by drop, adjust the pH of the solution to ≈8, then slowly add product B according to the mass ratio of aluminum source to product B (0.05-1.5): 1, continue stirring for 3-6 hours, and collect the powder by suction filtration , lotion, drying, and sieving to obtain precursor C;

Step 4: Sinter the precursor sample C in an inert gas atmosphere, raise the temperature to 300-400°C at a heating rate of 5-10°C/min, keep it warm for 0-60min, and cool naturally to room temperature to obtain the product D, namely Alumina-coated iron cyanamide.

The present invention also has the following technical characteristics:

Preferably, the grinding method in the step 1 is to use a mortar to grind for 20 minutes.

Preferably, the reactions of step 2 and step 4 are all carried out in a high-temperature tube furnace under a flowing argon or nitrogen atmosphere of 100 sccm.

Preferably, the aluminum source is aluminum nitrate nonahydrate, aluminum isopropoxide or aluminum hydroxide.

Preferably, the amphoteric surfactant in the third step is dodecyl ethoxy sultaine.

Preferably, the detergent method in the third step is to wash with deionized water for 2 to 3 times.

Preferably, the drying temperature in the third step is 80°C.

Preferably, the precursor C is obtained by passing through a 200-mesh sieve after drying in the third step.

The present invention also protects a kind of aluminum oxide-coated ferric cyanamide material prepared by using the sol-gel method to prepare alumina-coated ferric cyanamide material and its use as a high-performance potassium ion battery Application of negative electrode materials.

Compared with the prior art, the present invention has the following beneficial effects:

The present invention uses carbon and nitrogen-containing urea and ammonium iron oxalate as raw materials to prepare ferric cyanamide materials, and then performs a sol-gel method to obtain alumina-coated ferric cyanamide materials. The price of raw materials required for this technology synthesis Inexpensive, simple synthesis process, easy to operate, uniform coating and stable structure of the product, greatly reducing the generation of side reactions during the reaction process, thereby improving the electrochemical performance of the battery;

The alumina-coated ferric cyanamide material prepared in the present invention can be evenly coated on the surface of ferric cyanamide by using the gel gel method, which can effectively inhibit the direct contact between the electrolyte and the electrode material, and can significantly reduce the amount of material The side reaction phenomenon in the charging and discharging process, and the thickness can be adjusted by changing the solution concentration, so that the product structure is stable, the interface structure is stable, and it is not easy to be damaged. In addition, alumina coating can effectively alleviate the structure caused by potassium ion intercalation/extraction The phenomenon of being destroyed, the final thermal sintering in an inert atmosphere can make the alumina and ferric cyanamide tightly coated and not easy to fall off;

The present invention adds amphoteric surfactant (dodecyl ethoxy sulfobetaine) in the ferric cyanamide material process of preparing aluminum oxide coating, promotes the adsorption of aluminum oxide on the iron cyanamide surface, makes aluminum oxide Uniform growth on the surface of ferric cyanamide;

The aluminum oxide-coated ferric cyanamide material prepared by this technology has extremely high potassium ion storage performance, high charge and discharge capacity and excellent cycle performance.

Description of drawings

Fig. 1 is the TEM figure of embodiment 1

Fig. 2 is the cycle performance test figure of the negative electrode material of the battery prepared by the product of embodiment 1

Fig. 3 is the XRD pattern of examples 2 product

Fig. 4 is the TEM figure of embodiment 2 product

Fig. 5 is the cycle performance test chart of the negative electrode material of the battery prepared by the product of Example 2

Fig. 6 is the TEM figure of embodiment 3 products

Detailed ways

Example 1:

Step 1: Take 1g of ferric ammonium oxalate and 1.67g of urea, mix and grind them in a glass mortar for 20min to obtain mixture A;

Step 2: Transfer the mixture A to a quartz crucible, place the quartz crucible in a tube furnace, and raise the temperature to 160°C at a rate of 30°C/min in 100sccm flowing argon, keep it warm for 1h, and then Raise the temperature to 600°C at a rate of 5°C/min, take it out after cooling, and obtain product B;

Step 3: Dissolve 0.0735g of aluminum nitrate nonahydrate and 0.735g of dodecylethoxy sulfobetaine in 30ml of deionized water to obtain a solution with an aluminum ion concentration of 0.007mol/L, mechanically stir for 30min, and then Add ammonia water with a mass concentration of 15% dropwise to adjust the pH of the solution to ≈8, then slowly add 0.1 g of product B and amphoteric surfactant, continue stirring for 3 hours, filter with suction, wash with deionized water for 2 to 3 times, and dry at 80°C dry, and pass through a 200-mesh sieve to obtain precursor C.

Step 4: Sinter the precursor sample C in a tube furnace, raise the temperature to 300°C at a rate of 10°C/min in a flowing argon atmosphere of 100 sccm, keep it warm for 30 minutes, and cool naturally to room temperature to obtain product D , that is, the aluminum oxide-coated ferric cyanamide product whose mass ratio of alumina to ferric cyanamide is 1.0%.

Example 2:

Step 1: Take 1.2g ferric ammonium oxalate and 2g urea, mix and grind them in a glass mortar for 20min to obtain mixture A;

Step 2: Transfer the mixture A to a quartz crucible, place the quartz crucible in a tube furnace, and raise the temperature to 160°C at a rate of 30°C/min in a flowing nitrogen gas of 100 sccm, keep it warm for 1 hour, and then heat it for 5 The heating rate of °C/min was raised to 600 °C, and the product was taken out after cooling to obtain the product B;

Step 3: Take 0.1103g of aluminum hydroxide and 0.5515g of dodecyl ethoxy sulfobetaine and dissolve them in 30ml of deionized water, stir mechanically for 30min to obtain a solution with an aluminum ion concentration of 0.009mol/L, and then gradually Add ammonia water with a mass concentration of 15% dropwise, adjust the pH of the solution to ≈8, then slowly add 0.1g of product B, continue stirring for 4 hours, filter with suction, wash with deionized water for 2 to 3 times, dry at 80°C, and pass through a 200-mesh sieve Network, to obtain the precursor C.

Step 4: Sinter the precursor sample C in a tube furnace, raise the temperature to 350°C at a rate of 8°C/min in a flowing nitrogen atmosphere of 100 sccm, keep it warm for 40 minutes, and naturally cool to room temperature to obtain product D. That is, the aluminum oxide-coated ferric cyanamide product whose mass ratio of alumina to ferric cyanamide is 1.5%.

Example 3:

Step 1: Take 0.6g of ammonium oxalate ferric salt and 1g of urea, mix and grind them in a glass mortar for 20min to obtain mixture A;

Step 2: Transfer the mixture A to a quartz crucible, place the quartz crucible in a tube furnace, and raise the temperature to 160°C at a rate of 30°C/min in 100sccm flowing argon, keep it warm for 1h, and then Raise the temperature to 600°C at a rate of 5°C/min, take it out after cooling, and obtain product B;

Step 3: Get 0.147g of aluminum nitrate nonahydrate and 0.0147g of dodecyl ethoxy sulfobetaine and dissolve them in 30ml of deionized water, mechanically stir for 30min to obtain a solution with an aluminum ion concentration of 0.013mol/L, and then Add ammonia water with a mass concentration of 15% dropwise to adjust the pH of the solution to ≈8, then slowly add 0.1g of product B, continue stirring for 5 hours, filter with suction, wash with deionized water for 2 to 3 times, dry at 80°C, and pass through 200 mesh sieve to obtain precursor C.

Step 4: Place the precursor sample C in a tube furnace for sintering, heat up to 400°C at a rate of 5°C/min in a flowing argon atmosphere of 100 sccm, and cool naturally to room temperature to obtain product D, which is oxidized The aluminum oxide-coated ferric cyanamide product whose mass ratio of aluminum to ferric cyanamide is 2%.

Example 4:

Step 1: Take 0.9g of ferric ammonium oxalate and 1.5g of urea, mix and grind them in a glass mortar for 20min to obtain mixture A;

Step 2: Transfer the mixture A to a quartz crucible, place the quartz crucible in a tube furnace, and raise the temperature to 160°C at a rate of 30°C/min in 100sccm flowing argon, keep it warm for 1h, and then Raise the temperature to 600°C at a rate of 5°C/min, take it out after cooling, and obtain product B;

Step 3: Dissolve 0.00735g of aluminum isopropoxide and 0.0735g of dodecyl ethoxy sulfobetaine in 30ml of deionized water, and mechanically stir for 30min to obtain a solution with an aluminum ion concentration of 0.0007mol/L, and then Add ammonia water with a mass concentration of 15% drop by drop, adjust the pH of the solution to ≈8, then slowly add 0.1g of product B, continue stirring for 6 hours, filter with suction, wash with deionized water for 2 to 3 times, dry at 80°C, and pass through 200 mesh sieve to obtain precursor C.

Step 4: Sinter the precursor sample C in a tube furnace, raise the temperature to 300°C at a rate of 10°C/min in a flowing argon atmosphere of 100 sccm, keep it warm for 60 minutes, and cool naturally to room temperature to obtain product D , that is, the aluminum oxide-coated ferric cyanamide product whose mass ratio of alumina to ferric cyanamide is 1%.

The product of Example 1 was observed under a transmission electron microscope. It can be seen from FIG. 1 that the surface of the product structure is evenly covered by alumina. The product obtained in Example 1 is prepared into a button-type potassium ion battery, and the specific encapsulation steps are as follows: active powder, conductive agent (SuperP), conductive graphite, adhesive (carboxymethyl cellulose CMC), polyacrylic acid (PAA ) according to the mass ratio of 8:0.5:0.5:0.5:0.5, grind evenly, make a slurry, apply the slurry evenly on the copper foil with a film applicator, and then dry it in a vacuum oven at 80°C for 12h . Afterwards, the electrode sheets were assembled into a potassium-ion half-battery, and the battery was subjected to a constant-current charge-discharge test using the Xinwei Electrochemical Workstation. The test voltage was 0.01V-3.0V, and the obtained material was assembled into a button battery to test the performance of the negative electrode material of the potassium-ion battery. , as shown in Figure 2, the battery exhibited a capacity of 494mAh/g at a current density of 100mA/g, and a capacity of 420mAh/g after 150 cycles. It can be seen that the material has excellent cycle performance and charge-discharge capacity.

The product obtained in Example 2 was analyzed using a Japanese Rigaku D/max2000PCX-ray diffractometer, see accompanying drawing 3, the position of the peak corresponds to the iron cyanamide standard card. Fig. 4 is the TEM picture of the product obtained in Example 2, it can be seen that thicker alumina is coated on ferric cyanamide, and the product obtained in Example 2 is prepared into a button-type potassium ion battery, and the specific packaging steps are as follows : Grinding active powder, conductive agent (SuperP), conductive graphite, binder (carboxymethyl cellulose CMC), polyacrylic acid (PAA) according to the mass ratio of 8:0.5:0.5:0.5:0.5 evenly , to make a slurry, apply the slurry evenly on the copper foil with a film applicator, and then dry it in a vacuum oven at 80°C for 12h. Afterwards, the electrode sheets were assembled into a potassium-ion half-battery, and the battery was subjected to a constant-current charge-discharge test using the Xinwei Electrochemical Workstation. The test voltage was 0.01V-3.0V, and the obtained material was assembled into a button battery to test the performance of the negative electrode material of the potassium-ion battery. , as shown in Figure 5 cycle performance test, the battery exhibited a capacity of 305mAh/g at a current density of 100mA/g, and only 120mAh/g after 100 cycles.

The product obtained in Example 3 was observed under a transmission electron microscope. It can be seen from FIG. 6 that the surface of the product structure is covered unevenly by very thick alumina.

Claims (9)

1. A method for preparing an aluminum oxide coated iron cyanamide material by using a sol-gel method is characterized by comprising the following steps:

the method comprises the following steps: weighing ammonium oxalate iron salt and urea according to the mass ratio of 3;

step two: in an inert gas atmosphere, firstly heating to 160 ℃ at a heating rate of 30 ℃/min, preserving heat for 1h, then heating to 600 ℃ at a heating rate of 5 ℃/min, stopping the procedure after heating is finished, and taking out the product B which is the cyanamide iron under the condition that the temperature is reduced to room temperature;

step three: weighing an aluminum source and an amphoteric surfactant according to a mass ratio of 1 to 10, dissolving the aluminum source and the amphoteric surfactant in deionized water, stirring for 30min to fully dissolve the aluminum source and the amphoteric surfactant to obtain a solution with the aluminum ion concentration of 0.0007 to 0.013mol/L, dropwise adding ammonia water with the mass concentration of 15%, adjusting the pH of the solution to be approximately equal to 8, and then, according to the mass ratio of the aluminum source to a product B (0.05 to 1.5): 1, slowly adding the product B, continuously stirring for 3-6h, performing suction filtration to collect powder, washing the powder, drying the powder, and sieving the powder to obtain a precursor C; the amphoteric surfactant is dodecyl ethoxy sulfobetaine;

step four: and sintering the precursor sample C in an inert gas atmosphere, heating to 300-400 ℃ at a heating rate of 5-10 ℃/min, preserving heat for 0-60min, and naturally cooling to room temperature to obtain a product D, namely the aluminum oxide coated iron cyanamide.

2. The method for preparing an alumina-coated iron cyanamide material according to claim 1, wherein the grinding method in the first step is grinding for 20min with a mortar.

3. The method for preparing an alumina-coated iron cyanamide material according to claim 1, wherein the reactions of the second and fourth steps are performed in a high temperature tube furnace in an atmosphere of flowing argon or nitrogen of 100 sccm.

4. The method for producing an alumina-coated iron cyanamide material according to claim 1, wherein the aluminum source is aluminum nitrate nonahydrate, aluminum isopropoxide or aluminum hydroxide.

5. The method for preparing an alumina-coated iron cyanamide material according to claim 1, wherein the washing method in the third step is washing with deionized water for 2 to 3 times.

6. The method for preparing an alumina-coated iron cyanamide material according to claim 5, wherein the drying temperature in the third step is 80 ℃.

7. The method for preparing the alumina-coated iron cyanamide material according to claim 6, wherein the precursor C is obtained by drying and sieving with a 200-mesh sieve in the third step.

8. An alumina-coated iron cyanamide material prepared by the method for preparing an alumina-coated iron cyanamide material using the sol-gel method as claimed in claims 1 to 7.

9. The use of the alumina-coated iron cyanamide material of claim 8 as a negative electrode material for a high performance potassium ion battery.

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