CN106976847A - A kind of two selenizing ferrum nano materials and its synthetic method and application - Google Patents

Abstract

The invention provides a nano-material of iron diselenide and its synthesis method and application. The nano-material is a nano-sheet structure, and also provides a method for hydrothermally synthesizing _FeSe2 nano-sheets, using sodium borohydride to reduce selenium powder, Then react with ferric chloride hexahydrate, and prepare iron diselenide material by controlling the dosage of ferric chloride hexahydrate. The method controls the synthesis of nanometer-sized iron diselenide materials under high pressure. Compared with the existing methods, the present invention has the advantages of simple and fast preparation process, low cost and environmental friendliness, and the synthesized nanomaterials have good conductivity , applicable to the field of electrochemistry.

Description

A kind of iron diselenide nanometer material and its synthesis method and application

technical field

The invention belongs to the field of nanomaterial synthesis and electrochemistry, in particular, relates to iron diselenide nanomaterials and a synthesis method thereof, and the synthesized iron diselenide (FeSe ₂ ) has good conductivity and can be used as a sodium ion battery anode material.

Background technique

Energy shortage and environmental pollution have become a very serious problem of widespread concern in today's society. The greenhouse effect caused by the burning of fossil fuels is the most prominent, which seriously affects people's life and health. Therefore, looking for efficient energy storage and environmentally friendly devices has become a global hotspot. . Due to the advantages of high energy density and environmental protection, Li-ion batteries, Na-ion batteries, etc. have become promising candidates for energy storage devices, which have been widely used in smartphones, laptops, and electric vehicles. Compared with lithium-ion batteries, sodium-ion batteries are rich in resources and low in consumption, and thus sodium-ion batteries have attracted more interest. Due to the higher radius and molar mass of sodium ions than lithium ions, sodium ion batteries have low capacity, short life, and large volume changes during charge and discharge, so suitable electrode materials, especially anode materials, play a key role in the performance of sodium ion batteries. Therefore, the research on anode materials for sodium-ion batteries has become a challenging topic.

Transition metals have good electrical conductivity. Transition metal oxides and sulfides have been reported as anode materials for sodium-ion batteries. Transition metal selenides have similar chemical properties to transition metal oxides and sulfides, but the research on them is relatively limited. few. Iron diselenide is rich in resources, low in price, stable in chemical properties, environmentally friendly and non-toxic, and is a suitable anode material for sodium-ion batteries. Zhang's research group (DOI: 10.1021/acsami.5b12148) reported a synthesis method of iron diselenide microspheres, and studied its electrochemical performance as an anode material for sodium-ion batteries, but the diameter of the microspheres is large (2 -5μm), which is not conducive to the diffusion reaction of the electrolyte into the material.

Therefore, it has always been the goal of researchers to explore anode materials with application value for sodium ion batteries.

Contents of the invention

The invention provides an iron diselenide nanomaterial and its synthesis method and application. The iron diselenide nanosheet is synthesized by a hydrothermal method. The synthesis method is simple in process and easy to operate, and the prepared iron diselenide material is used as a sodium ion The anode material of the battery exhibits good electrochemical performance.

The present invention adopts following technical scheme to realize:

The invention relates to an iron diselenide nanometer material, which is a nanosheet structure.

The present invention also provides a synthetic method for hydrothermally synthesizing iron diselenide (FeSe ₂ ) nanosheets, specifically comprising the following steps:

1) Take a certain amount of deionized water and add it to the beaker, and feed nitrogen to remove the oxygen in the water;

2) adding sodium borohydride and selenium powder into the beaker of step 1), and magnetically stirring to make it react;

3) Add a certain quality of ferric chloride hexahydrate (FeCl ₃ 6H ₂ O) into the beaker of step 1), and continue stirring;

4) After reacting for a certain period of time, stop stirring, transfer the liquid in the beaker of step 1) to an autoclave, and put it into an oven to react at a certain temperature.

5) After the reaction is completed, the reactor is taken out to cool down, and the product is washed and dried.

In the step 1), nitrogen gas is introduced to remove the oxygen in the ionized water, and the required time is 20 to 50 minutes.

Step 2) Sodium borohydride is used as a reducing agent, and the molar ratio of its added amount to the added amount of selenium powder ranges from 1 to 2:1.

Step 3) The molar ratio of the added amount of ferric chloride hexahydrate to the added amount of selenium powder ranges from 0.5 to 1:1.

After the liquid in step 4) is transferred into the autoclave, nitrogen can be passed to remove oxygen. The reaction temperature is 150-220° C., and the reaction time is 12-30 hours.

The application of the iron diselenide nanometer material in the anode material of sodium ion battery.

The invention uses sodium borohydride as a reducing agent to rapidly synthesize sheet-shaped iron diselenide nanoparticles under high pressure through a simple hydrothermal synthesis technique. Since the electrochemical reaction in the charging and discharging process only occurs on the surface of the material, the two-dimensional sheet structure has a larger exposed specific surface area, a larger contact area with the electrolyte, more active sites, more likely to react, and a higher capacity. . Compared with the prior art, the invention has the advantages of simple and fast preparation process, low cost, and environmental friendliness.

Iron diselenide to prepare sodium-ion batteries:

Grind the obtained ferric diselenide material with acetylene black and sodium carboxymethyl cellulose in a ratio of 8:1:1, and when grinding until no particles exist, add deionized water drop by drop and continue grinding, Grind it to a certain degree, apply it evenly on the copper foil, first dry it at room temperature, and then dry it in vacuum for 6 hours. The dried copper foil was cut into pieces with a diameter of 12 mm each by a tablet press, and then a sodium-ion battery was assembled in a glove box, and the battery model was CR2032 (3V). After the assembled battery is placed for more than 12 hours, it can be tested with a constant current charge and discharge with a blue battery tester. The voltage range is 0.5V to 2.9V, and the cyclic voltammetry curve can be tested with an electrochemical workstation.

Compared with the prior art, the advantages and positive effects of the present invention are: the preparation process of the nanometer material is simple, low consumption and easy to operate, and the prepared battery has good constant current charge and discharge performance.

Description of drawings

Fig. 1 is the scanning electron microscope picture of the iron diselenide nanosheet that embodiment 1 prepares;

Fig. 2 is the transmission electron microscope picture of the iron diselenide nanosheet that embodiment 1 prepares;

Fig. 3 is the high-resolution transmission electron microscope picture of the iron diselenide nanosheet prepared in embodiment 1;

Fig. 4 is the XRD picture of the iron diselenide nanosheet prepared in embodiment 1;

Fig. 5 is the cycle performance picture under the current density of 100mA/g of the sodium ion battery prepared in embodiment 1;

Figure 6 is a picture of the rate performance of the sodium ion battery prepared in Example 1 at different current densities;

Fig. 7 is the picture of the cyclic voltammetry curve of the sodium ion battery prepared in Example 1 at different scan rates;

Fig. 8 is the picture of the first three times of charge and discharge of the sodium ion battery prepared in Example 1 at a current density of 100mA/g;

Fig. 9 is the scanning electron microscope picture of the iron diselenide nanosheet prepared in embodiment 2;

Fig. 10 is the transmission electron microscope picture of the iron diselenide nanosheet prepared in embodiment 2;

Fig. 11 is the scanning electron microscope picture of the iron diselenide nanosheet prepared in embodiment 3;

Fig. 12 is the transmission electron microscope picture of the iron diselenide nanosheet prepared in embodiment 3;

FIG. 13 is a transmission electron microscope picture of the iron diselenide nanosheets prepared in Example 4.

detailed description

The present invention will be described in further detail below in conjunction with the embodiments and drawings, but this description will not constitute a limitation to the present invention.

Example 1

Preparation of FeSe Nanomaterials by Hydrothermal Synthesis

Measure 40mL of deionized water into the beaker, blow in nitrogen to remove the oxygen in the water. After 20 min, 2 mmol of sodium borohydride and 1 mmol of selenium powder were added, and magnetically stirred until the solution became clear. Then add 0.5mmol of ferric chloride hexahydrate, and continue to stir for 10min, nitrogen has been passed through during this process. After stirring, transfer the solution into the reaction kettle, continue to pass nitrogen for a while, then tighten the lid, put it in an oven, and react at 180°C for 24 hours. After the reaction was completed, the reaction kettle was taken out, allowed to cool in the air, and the product precipitated in the reaction kettle was washed several times by centrifugation with water and ethanol, respectively, and finally vacuum-dried at 60° C. for 12 hours.

Grind the iron diselenide material obtained above with acetylene black and sodium carboxymethyl cellulose in a ratio of 8:1:1, and when grinding until no particles exist, add deionized water drop by drop and continue grinding, Grind it to a certain degree, apply it evenly on the copper foil, first dry it at room temperature, and then dry it in vacuum for 6 hours. The dried copper foil was cut into pieces with a diameter of 12 mm each by a tablet press, and then a sodium-ion battery was assembled in a glove box, and the battery model was CR2032 (3V). After the assembled battery is placed for more than 12 hours, it can be tested with a constant current charge and discharge with a blue battery tester. The voltage range is 0.5V to 2.9V, and the cyclic voltammetry curve can be tested with an electrochemical workstation.

Figure 1 is a scanning electron microscope picture of the iron diselenide nanosheets prepared in Example 1. It can be seen that the synthesized iron diselenide nanomaterials are sheet-like structures.

2 is a transmission electron microscope picture of the iron diselenide nanosheets prepared in Example 1. It can be seen that the synthesized iron diselenide nanomaterials have a sheet-like structure, which is consistent with the scanning electron microscope picture.

FIG. 3 is a high-resolution transmission electron microscope image of the iron diselenide nanosheets prepared in Example 1. It can be seen that the interlayer spacing of the synthesized iron diselenide nanomaterial (1,1,1) is 0.257 nm.

Figure 4 is the XRD image of the iron diselenide nanosheets prepared in Example 1. It can be seen that the diffraction peak intensity of the synthesized iron diselenide nanomaterials is very strong, so the crystallinity of the synthesized iron diselenide nanomaterials is very good.

Figure 5 is a picture of the cycle performance of the sodium-ion battery prepared in Example 1 at a current density of 100mA/g. It can be seen that the battery has a specific capacity of 438.7mAh g ^-1 after 50 cycles of discharge at a low current density, and the cycle performance is very stable. Coulombic efficiency is close to 100%.

Figure 6 is a picture of the rate performance of the sodium ion battery prepared in Example 1 at different current densities. The specific capacity is quite stable after charging and discharging for 5 cycles at different current densities, and the specific capacity is quite stable at current densities of 0.1Ag ^-1 and 0.2Ag ^-1 , 0.4Ag ^-1 , 0.8Ag ^-1 , 1.0Ag ^-1 , 2.0Ag ^-1 the specific discharge capacities are 496mAh g ^-1 , 449mAh g ^-1 , 415mAh g -1 , ^375mAh g ^-1 , 360mAh g ^{-1 1.} 307mAh g ^-1 .

Figure 7 is a picture of the cyclic voltammetry curves of the sodium ion battery prepared in Example 1 at different scan rates, the scan rates are 0.2mV/s, 0.4mV/s, 0.6mV/s, 0.8mV/s, 1.0mV/s , it can be seen that there is one oxidation peak and three reduction peaks.

Fig. 8 is the picture of three cycles before charging and discharging the sodium ion battery prepared in Example 1 at a current density of 100mA/g.

Example 2

Preparation of FeSe Nanomaterials by Hydrothermal Synthesis

Measure 40mL of deionized water was added to the beaker, and nitrogen was introduced to remove the oxygen in the water. After 20 min, 2 mmol of sodium borohydride and 1 mmol of selenium powder were added, and magnetically stirred until the solution became clear. Then add 0.6mmol of ferric chloride hexahydrate, and continue to stir for 10min, nitrogen has been passed through during this process. After stirring, transfer the solution into the reaction kettle, continue to pass nitrogen for a while, then tighten the lid, put it in an oven, and react at 180°C for 24 hours. After the reaction was completed, the reaction kettle was taken out, allowed to cool in the air, and the product precipitated in the reaction kettle was washed several times by centrifugation with water and ethanol, respectively, and finally vacuum-dried at 60° C. for 12 hours.

The part of assembling the battery is the same as in Example 1.

9 is a scanning electron microscope picture of the iron diselenide nanosheets prepared in Example 2.

FIG. 10 is a transmission electron microscope image of the iron diselenide nanosheets prepared in Example 2, and it can be seen that the synthesized iron diselenide nanosheets are stacked together.

Example 3

Preparation of FeSe Nanomaterials by Hydrothermal Synthesis

Measure 40mL of deionized water was added to the beaker, and nitrogen was introduced to remove the oxygen in the water. After 20 min, 2 mmol of sodium borohydride and 1 mmol of selenium powder were added, and magnetically stirred until the solution became clear. Then add 1.0 mmol of ferric chloride hexahydrate, and continue to stir for 10 min, and nitrogen gas has been passed through during this process. After stirring, transfer the solution into the reaction kettle, continue to pass nitrogen for a while, then tighten the lid, put it in an oven, and react at 180°C for 24 hours. After the reaction was completed, the reaction kettle was taken out, allowed to cool in the air, and the product precipitated in the reaction kettle was washed several times by centrifugation with water and ethanol, respectively, and finally vacuum-dried at 60° C. for 12 hours.

The part of assembling the battery is the same as in Example 1.

FIG. 11 is a scanning electron microscope image of iron diselenide nanosheets prepared in Example 3.

12 is a transmission electron microscope image of the iron diselenide nanosheets prepared in Example 3, and it can be seen that the synthesized iron diselenide nanosheets are in an aggregated state.

Example 4

Preparation of FeSe Nanomaterials by Hydrothermal Synthesis

Measure 40mL of deionized water was added to the beaker, and nitrogen was introduced to remove the oxygen in the water. After 20 min, 2 mmol of sodium borohydride and 1 mmol of selenium powder were added, and magnetically stirred until the solution became clear. Then add 0.5 mmol of ferric nitrate nonahydrate, continue to stir for 10 min, and pass nitrogen gas all the time during this process. After stirring, transfer the solution into the reaction kettle, continue to pass nitrogen for a while, then tighten the lid, put it in an oven, and react at 180°C for 24 hours. After the reaction was completed, the reaction kettle was taken out, allowed to cool in the air, and the product precipitated in the reaction kettle was washed several times by centrifugation with water and ethanol, respectively, and finally vacuum-dried at 60° C. for 12 hours.

The part of assembling the battery is the same as in Example 1.

FIG. 13 is a transmission electron microscope picture of the iron diselenide nanosheets prepared in Example 4.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention to other forms. Any skilled person who is familiar with this profession can use the technical content disclosed above to change or remodel it into an equivalent of equivalent change. Example. However, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still belong to the protection scope of the technical solution of the present invention.

Claims (8)

1. An iron diselenide nanomaterial, characterized in that: the nanomaterial is a nano sheet structure. 2. a synthetic method for hydrothermally synthesizing iron diselenide nanosheets, is characterized in that, comprises the following steps: 1) Take a certain amount of deionized water and add it to the beaker, and feed nitrogen to remove the oxygen in the water; 2) adding sodium borohydride and selenium powder into the beaker of step 1), and magnetically stirring to make it react; 3) Add a certain quality of ferric chloride hexahydrate (FeCl ₃ 6H ₂ O) into the beaker of step 1), and continue stirring; 4) react for a certain period of time, stop stirring, transfer the liquid in the beaker of step 1) to an autoclave, and put it into an oven to react at a certain temperature; 5) After the reaction is completed, the reactor is taken out to cool down, and the product is washed and dried. 3. The synthesis method according to claim 2, characterized in that: in the step 1), nitrogen gas is introduced to remove the oxygen in the ionized water, and the required time is 20 to 50 minutes. 4. The synthesis method according to claim 2, characterized in that: in step 2), sodium borohydride is used as a reducing agent, and the molar ratio of its addition to the addition of selenium powder is in the range of 1 to 2:1. 5. The synthesis method according to claim 2, characterized in that: in step 3), the molar ratio of the added amount of ferric chloride hexahydrate to the added amount of selenium powder ranges from 0.5 to 1:1. 6. The synthetic method according to claim 2, characterized in that: after the liquid is transferred into the autoclave in step 4), nitrogen can be passed through to remove oxygen. 7. The synthesis method according to claim 2, characterized in that: in step 4), the reaction temperature is 150-220° C., and the reaction time is 12-30 h. 8. The application of the iron diselenide nanomaterial described in any one of the above claims 1-7 in the anode material of a sodium ion battery.