阅读说明：本技术 多孔硒化铁碳包覆复合材料及其在钾离子电池中的应用 (Porous iron selenide carbon-coated composite material and application thereof in potassium ion battery ) 是由 刘伶俐 孟祥贺 胡磊 余磊 于 2021-03-17 设计创作，主要内容包括：本发明公开了一种多孔硒化铁碳包覆复合材料及其在钾离子电池中的应用,涉及电池电极材料技术领域,本发明所述多孔硒化铁碳包覆复合材料由MIL-100(Fe)前驱体与硒粉发生的高温反应形成,并将该复合材料作为钾离子电池电极材料进行应用,其独特的碳包覆结构和介孔孔道有利于提高钾离子电池的循环性能和倍率性能,使用该复合材料制备的钾离子电池可以有效地解决了钾离子反应动力学较慢、电极材料体积膨胀的问题。(The invention discloses a porous iron selenide carbon-coated composite material and application thereof in a potassium ion battery, and relates to the technical field of battery electrode materials.)

1. A porous iron selenide carbon-coated composite material is characterized in that: the preparation method comprises the following steps:

(1) respectively dissolving ferric nitrate nonahydrate and benzenetricarboxylic acid in deionized water, mixing, adding hydrofluoric acid, stirring, transferring to a reaction kettle, and sealing;

(2) heating the mixture in the reaction kettle to a preset temperature at a certain heating rate to carry out heat preservation reaction;

(3) after the reaction is finished, centrifuging, washing and drying the reaction solution to obtain an MIL-100(Fe) precursor;

(4) mixing an MIL-100(Fe) precursor with selenium powder, carrying out ball milling by using a ball mill, and transferring the obtained mixture into a tube furnace;

(5) under the protection of inert gas, heating the mixture at a certain heating rate, carrying out heat preservation reaction, cooling after the reaction is finished, and taking out to obtain the porous iron selenide carbon-coated composite material.

2. The porous iron selenide carbon-coated composite material of claim 1, wherein: in the step (1), the mass ratio of the ferric nitrate nonahydrate to the benzenetricarboxylic acid is 2 (0.5-2), and the dosage of the hydrofluoric acid is 1-5mL per gram of the ferric nitrate nonahydrate.

3. The porous iron selenide carbon-coated composite material of claim 1, wherein: and (2) stirring time in the step (1) is 10-300 min.

4. The porous iron selenide carbon-coated composite material of claim 1, wherein: in the step (2), the heating rate is 0.1-20 ℃/min, the preset temperature is 100-200 ℃, and the heat preservation time is 8-12 h.

5. The porous iron selenide carbon-coated composite material of claim 1, wherein: in the step (4), the weight ratio of the MIL-100(Fe) precursor to the selenium powder is 1 (0.25-5).

6. The porous iron selenide carbon-coated composite material of claim 1, wherein: in the step (4), the rotating speed of the ball mill is 10-500 r/min, and the ball milling time is 1-4 h.

7. The porous iron selenide carbon-coated composite material of claim 1, wherein: in the step (5), the heating rate is 0.1-20 ℃/min, the heating temperature is 200-800 ℃, and the heat preservation time is 5-12 h.

8. The porous iron selenide carbon-coated composite material of claim 1, wherein: and (5) the inert atmosphere is gas which cannot react with the iron selenide and the MIL-100(Fe) precursor.

9. The porous iron selenide carbon-coated composite material of claim 1, wherein: the material of the reaction kettle in the steps (1) - (5) is a material which does not react with ferric nitrate, an MIL-100(Fe) precursor, iron selenide, selenium powder and carbon.

10. Use of the porous iron selenide carbon-coated composite material prepared according to any one of claims 1 to 9 in an electrode material of a potassium ion battery.

The technical field is as follows:

the invention relates to the technical field of battery electrode materials, in particular to a porous iron selenide carbon-coated composite material and application thereof in a potassium ion battery.

Background art:

in the past two decades, lithium batteries have been widely used in people's daily life due to their advantages of high energy density, good cycle performance, greenness and no pollution: cell phones, computers, electric vehicles, and the like. However, lithium metal is a scarce metal, and as the demand of lithium batteries increases greatly, lithium resources are rapidly consumed. Moreover, the energy density of the lithium battery gradually fails to meet the requirements of electric vehicles and large-scale energy storage power grids. Therefore, in the current situation, as the potassium metal is richer in resources and lower in cost compared with lithium, the potassium ion battery is produced as the next energy storage battery which has the opportunity of being marketed. The key factor for restricting the performance of the potassium ion battery is the cathode electrode material, and the finding of the cathode material with good cycle stability and high energy density is not easy.

Iron selenide is a material with good conductivity and high theoretical capacity, and is very suitable for optimizing the structure of the material by carbon coating. Therefore, the carbon-coated iron selenide increases the porous pore channels, shortens the transmission path of potassium ions, improves the ion transmission rate and improves the electrochemical performance of the potassium ion battery.

The invention content is as follows:

the invention aims to provide a porous iron selenide carbon-coated composite material, and when the prepared porous iron selenide carbon-coated composite material is applied as an electrode material of a potassium ion battery, the cycle performance of the potassium ion battery can be obviously improved, and the porous iron selenide carbon-coated composite material has excellent cycle stability.

One purpose of the invention is to provide a porous iron selenide carbon-coated composite material, and the preparation method comprises the following steps:

(1) respectively dissolving ferric nitrate nonahydrate and benzenetricarboxylic acid in deionized water, mixing, adding hydrofluoric acid, stirring, transferring to a reaction kettle, and sealing;

(2) heating the mixture in the reaction kettle to a preset temperature at a certain heating rate to carry out heat preservation reaction;

(3) after the reaction is finished, centrifuging, washing and drying the reaction solution to obtain an MIL-100(Fe) precursor;

(4) mixing an MIL-100(Fe) precursor with selenium powder, carrying out ball milling by using a ball mill, and transferring the obtained mixture into a tube furnace;

(5) under the protection of inert gas, heating the mixture at a certain heating rate, carrying out heat preservation reaction, cooling after the reaction is finished, and taking out to obtain the porous iron selenide carbon-coated composite material.

In the step (1), the mass ratio of the ferric nitrate nonahydrate to the benzenetricarboxylic acid is 2 (0.5-2), the dosage of hydrofluoric acid is 1-5mL of hydrofluoric acid used per gram of ferric nitrate nonahydrate, and the stirring time is 10-300 min.

In the step (2), the heating rate is 0.1-20 ℃/min, the preset temperature is 100-200 ℃, and the heat preservation time is 8-12 h.

In the step (4), the weight ratio of the MIL-100(Fe) precursor to the selenium powder is 1 (0.25-5), the rotating speed of the ball mill is 10-500 r/min, and the ball milling time is 1-4 h.

In the step (5), the heating rate is 0.1-20 ℃/min, the heating temperature is 200-800 ℃, and the heat preservation time is 5-12 h.

The inert atmosphere in the step (5) is a gas which does not react with the iron selenide and the MIL-100(Fe) precursor, such as argon, helium/argon mixed gas and the like.

The material of the reaction kettle in the steps (1) - (5) is a material which does not react with ferric nitrate, an MIL-100(Fe) precursor, iron selenide, selenium powder and carbon, such as polytetrafluoroethylene.

The invention also aims to provide application of the porous iron selenide carbon-coated composite material in an electrode material of a potassium ion battery.

The invention has the beneficial effects that: compared with the prior art, the invention provides the porous iron selenide carbon-coated composite material which is simple, effective and easy for industrial production. The precursor MIL-100(Fe) is provided with a micropore opening and a mesopore cage, the micropore opening is beneficial to the selenium and the vertex metal to fully react, and the calcined mesopore structure is continuously maintained. Because the potassium ions have larger size, the specific mesoporous structure of the potassium ions is beneficial to the intercalation/deintercalation of the potassium ions, the transmission path of the potassium ions is shortened, and the improvement of the potassium ion transmission pathThe specific capacity of the electrode material is shown. The carbon skeleton formed by carbon coating can effectively limit the volume expansion of the iron selenide in the charging and discharging processes, and greatly improves the cycle performance of the potassium ion battery. Under the long-cycle charge and discharge test condition, the discharge capacity is 500mAg^-1At a current density of (1), the capacity of the capacitor was maintained at 308mA hr g after 1000 charge-discharge cycles^-1The porous iron selenide carbon coating material is proved to have excellent cycling stability in the potassium ion battery. Wherein, under the condition of multiplying power charge-discharge test, the ratio is 1000mAg^-1And 2000mAg^-1Under the high multiplying current density, the capacity of the capacitor still remains 276mA h g^-1And 254mA h g^-1. Compared with the selenide positive electrode material of the same type in the potassium ion battery, the porous iron selenide carbon-coated potassium ion battery electrode material prepared by the invention has excellent performance, and the preparation method is simple and is suitable for industrial production.

Description of the drawings:

fig. 1 is an X-ray diffraction pattern (a), a thermogravimetric analysis pattern (b), a nitrogen adsorption and desorption graph (c), and an X-ray spectral analysis pattern (d-f) of the porous iron selenide carbon-coated composite material prepared in example 1 of the present invention;

fig. 2 is a transmission electron microscope image of the porous iron selenide carbon-coated composite material prepared in example 1 of the present invention;

fig. 3 is a graph of rate capability of the porous iron selenide carbon-coated composite material prepared in example 1 of the present invention;

fig. 4 is a long cycle charge and discharge performance graph of the porous iron selenide carbon-coated composite material prepared in example 1 of the present invention;

fig. 5 is a high-rate cycle charge-discharge performance diagram of the porous iron selenide carbon-coated composite material prepared in example 1 of the present invention.

The specific implementation mode is as follows:

in order to make the technical means, the original characteristics, the achieved purposes and the effects of the invention easy to understand, the invention is further explained by combining the specific embodiments and the drawings.

Example 1

2g of ferric nitrate nonahydrate and 1.2g of benzenetricarboxylic acid are respectively dissolved in 25mL of deionized water, mixed, added with 1mL of hydrofluoric acid, and stirred for 30 min. Transferring the mixture into a reaction kettle, keeping the temperature at 150 ℃ for 12h, and increasing the temperature at the rate of 2 ℃/min. After cooling, the mixture was washed and centrifuged. And (3) placing the sample in a vacuum drying oven at 80 ℃ for 12h, and drying to obtain an MIL-100(Fe) precursor.

Taking 200mg of MIL-100(Fe) precursor and 300mg of selenium powder, and ball-milling for 2h at the rotating speed of 200r/min by using a ball mill for mixing. The mixture was placed in a tube furnace and heated at a rate of 5 ℃/min under an argon atmosphere, first at 260 ℃ for 5h and then at 720 ℃ for 4 h. And after the reaction is finished, taking out the black solid after the reaction to obtain the porous iron selenide carbon-coated composite material.

Example 2

2g of ferric nitrate nonahydrate and 1.5g of benzenetricarboxylic acid are respectively dissolved in 25mL of deionized water, and after mixing, 2mL of hydrofluoric acid is added and stirring is carried out for 30 min. Transferring the mixture into a reaction kettle, keeping the temperature at 160 ℃ for 12h, and increasing the temperature at the rate of 2 ℃/min. After cooling, the mixture was washed and centrifuged. And (3) placing the sample in a vacuum drying oven at 80 ℃ for 12h, and drying to obtain an MIL-100(Fe) precursor.

300mg of MIL-100(Fe) precursor and 300mg of selenium powder are taken, and ball milling is carried out for 2h by a ball mill at the rotating speed of 400r/min for mixing. The mixture was placed in a tube furnace and heated at a rate of 5 ℃/min under the protection of argon atmosphere, first at 280 ℃ for 3h and then at 720 ℃ for 4 h. And after the reaction is finished, taking out the black solid after the reaction to obtain the porous iron selenide carbon-coated composite material.

Example 3

2g of ferric nitrate nonahydrate and 1.6g of benzenetricarboxylic acid are respectively dissolved in 25mL of deionized water, mixed, added with 1mL of hydrofluoric acid, and stirred for 30 min. Transferring the mixture into a reaction kettle, keeping the temperature at 170 ℃ for 12h, and increasing the temperature at the rate of 2 ℃/min. After cooling, the mixture was washed and centrifuged. And (3) placing the sample in a vacuum drying oven at 80 ℃ for 12h, and drying to obtain an MIL-100(Fe) precursor.

120mg of MIL-100(Fe) precursor and 200mg of selenium powder are taken, and ball milling is carried out for 2h by a ball mill at the rotating speed of 200r/min for mixing. The mixture was placed in a tube furnace and heated at a rate of 5 ℃/min under a blanket of argon, first at 260 ℃ for 2h and then at 720 ℃ for 4 h. And after the reaction is finished, taking out the black solid after the reaction to obtain the porous iron selenide carbon-coated composite material.

Example 4

3g of ferric nitrate nonahydrate and 1.2g of benzenetricarboxylic acid are respectively dissolved in 25mL of deionized water, and after mixing, 2mL of hydrofluoric acid is added and stirring is carried out for 30 min. Transferring the mixture into a reaction kettle, keeping the temperature at 140 ℃ for 12h, and increasing the temperature at the rate of 2 ℃/min. After cooling, the mixture was washed and centrifuged. And (3) placing the sample in a vacuum drying oven at 80 ℃ for 12h, and drying to obtain an MIL-100(Fe) precursor.

Taking 200mg of MIL-100(Fe) precursor and 28mg of selenium powder, and ball-milling for 2h at the rotating speed of 200r/min by using a ball mill for mixing. The mixture was placed in a tube furnace and heated at a rate of 5 ℃/min under an argon atmosphere, first at 250 ℃ for 5h and then at 720 ℃ for 4 h. And after the reaction is finished, taking out the black solid after the reaction to obtain the porous iron selenide carbon-coated composite material.

Example 5

2g of ferric nitrate nonahydrate and 1.6g of benzenetricarboxylic acid are respectively dissolved in 25mL of deionized water, and after mixing, 2mL of hydrofluoric acid is added and stirring is carried out for 30 min. Transferring the mixture into a reaction kettle, keeping the temperature at 160 ℃ for 12h, and increasing the temperature at the rate of 2 ℃/min. After cooling, the mixture was washed and centrifuged. And (3) placing the sample in a vacuum drying oven at 80 ℃ for 12h, and drying to obtain an MIL-100(Fe) precursor.

Taking 150mg of MIL-100(Fe) precursor and 300mg of selenium powder, and ball-milling for 2h at the rotating speed of 300r/min by using a ball mill for mixing. The mixture was placed in a tube furnace and heated at a rate of 5 ℃/min under the protection of argon atmosphere, first at 280 ℃ for 4h and then at 720 ℃ for 4 h. And after the reaction is finished, taking out the black solid after the reaction to obtain the porous iron selenide carbon-coated composite material.

Performance evaluation:

the button cell assembling method required by the test is as follows: the composite material obtained in the example 1, carbon black and CMC (sodium carboxymethylcellulose) are uniformly mixed according to the ratio of 7:2:1, a certain amount of water is dripped, mixed slurry is prepared by grinding and coated on a copper foil, the copper foil is dried for 12 hours in a vacuum oven at the temperature of 110 ℃, a pole piece is rolled on a rolling machine, and then the pole piece is cut into a circular pole piece with the diameter of 12 mm. The cell assembly was carried out in a glove box filled with argon, the electrolyte was 3M KFSI EC/DEC, the negative electrode was a potassium metal sheet, and the performance test was performed on blue CT 2001A.

The rate test is 100mAg at 25 deg.C^-1、300mAg^-1、500mAg^-1、1000mA g^-1And 2000mA g^-1The current density of (a) was tested for rate and experimental data were recorded and the results are shown in fig. 3. Long cycle charge and discharge test at 500mA g^-1The current density of (a) was subjected to a charge-discharge cycle test, and the experimental results are shown in fig. 4. At 1000mA g^-1100 charge-discharge cycles were tested at high current densities, and the experimental results are shown in figure 5.

The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.