Preparation method of Cu3N nano material for sodium battery

Abstract

The invention discloses a preparation method of a Cu3N nano material for a sodium battery and belongs to the field of sodium ion batteries. The nano material is in a nano particle shape. According to the Cu3N nano-particles, a one-step low-temperature annealing treatment method is adopted, copper acetylacetonate serves as a copper source, ammonium fluoride serves as a nitrogen source, and the Cu3N nano-material is synthesized through low-temperature sintering. The material has the characteristics of high purity and different particle sizes. When the material is used as a negative electrode material of a sodium battery for an electrochemical performance test, the initial specific capacity of the material can reach 593.6 mAh / g (0.2 A / g), and the specific capacity of the material is still 254.3 mAh / g after 100 cycles. The Cu3N nano electrode material prepared by the invention has the characteristics of high specific capacity, good cycle performance, simple preparation method and the like.

Description

Technical Field

[0001] The invention discloses a method for preparing Cu3N nanomaterial for sodium electricity, belonging to the field of sodium ion batteries. Technical Background

[0002] With the improvement of people's environmental awareness and the introduction of national policies, the demand for the development of new green energy (such as solar energy, wind energy, etc.) and high-performance energy storage devices has been greatly promoted. Due to the influence of lithium resource reserves and prices, coupled with the popularity of new energy electric vehicles, the consumption of lithium resources has increased, further pushing up its price, making it difficult for lithium batteries to meet the application requirements of large-scale energy storage. On the contrary, sodium resources have the advantages of high reserves and low prices. At the same time, sodium and lithium belong to the same group of elements and have similar properties, so sodium-ion batteries can meet the requirements of large-scale energy storage applications.

[0003] The research and development of high-performance negative electrode materials is one of the key factors in promoting the practical application of sodium-ion batteries. Transition metal nitrides, especially transition metal copper nitride, have the advantages of high theoretical specific capacity and high electronic conductivity, and have received widespread attention. Most of the existing literature uses a liquid phase method to synthesize precursors, and then uses a high-temperature annealing method. Most of them use ammonia gas with strong irritation as a nitrogen source, and a few use urea. However, there are few reports on the use of ammonium fluoride as a nitrogen source for the preparation of copper nitride. In addition, the existing preparation process is relatively cumbersome and can easily lead to the presence of impurities in the product. In addition, some preparation methods are costly, which is not conducive to large-scale preparation in actual industrialization. Summary of the invention

[0004] The present invention provides a method with simple preparation process, short cycle and easy operation. The Cu3N nanomaterial is successfully prepared by a one-step low-temperature annealing synthesis method. When the Cu3N nanomaterial is used as the negative electrode of a sodium ion battery, the Cu3N nanomaterial has good electrochemical performance.

[0005] The present invention provides a method for preparing a Cu3N nanomaterial for sodium electricity, which comprises the following steps:

[0006] a) Add ammonium fluoride and copper acetylacetonate into a ceramic ark with a length and width of 45*22 mm, and then cover it with another empty ceramic ark of the same specification;

[0007] b) placing the ceramic ark in a tube furnace, continuously introducing argon gas at a ventilation rate of 24 sccm, heating the temperature from room temperature to a predetermined temperature at a heating rate of 4°C / min, and after a period of heat preservation, cooling the temperature down to room temperature with the furnace to obtain a Cu3N nanomaterial;

[0008] c) The Cu3N nanomaterial is used as an electrode material in a sodium ion battery.

[0009] In the step a), the ammonium fluoride powder is spread on the bottom of the ceramic ark, and the copper acetylacetonate powder is spread on the ammonium fluoride powder; when the amount of copper acetylacetonate added is 0.8 g, the amount of ammonium fluoride added is in the range of 0.5 to 0.9 g.

[0010] In the step b), the temperature is raised to 300° C. at a heating rate of 4° C. / min under the condition that the argon gas ventilation rate is 24 sccm, and the temperature is kept at this temperature for 2 hours;

[0011] In the sodium ion battery cycle performance test of step c), the initial discharge specific capacity can reach 593.6 mAh / g at 0.2 A / g, and even after 100 cycles, the specific capacity is still 254.3 mAh / g.

[0012] Compared with other methods for preparing Cu3N materials, this method greatly simplifies the preparation process, has a short cycle, and is suitable for large-scale mass production; more importantly, when pure-phase Cu3N nanomaterials are used in sodium-ion batteries, they have higher specific capacity and cycle performance.

[0013] The X-ray powder diffractometer was used with Bruker Advance D8 (CuKα radiation, The structure of the prepared material was determined by scanning electron microscope (SEM) with a wavelength of 2θ=10-75°. The surface morphology of the prepared material was observed by scanning electron microscope (SEM) with a Hitachi S-4800. The battery performance was tested by electrochemical workstation (CHI 660E) and Neware battery test system.

[0014] Depend on Figure 1 It can be seen that when the amount of copper acetylacetonate added is 0.8g and the amount of ammonium fluoride added is 0.5g, 0.7g and 0.9g respectively, the corresponding molar ratios of copper acetylacetonate to ammonium fluoride are 1 / 4.43, 1 / 6.2 and 1 / 7.97 respectively, and the diffraction peaks of the obtained products are all attributed to the diffraction peaks of Cu3N (JCPDS card No.86-2283), and no diffraction peaks of other substances are obviously observed, indicating that when the amount of ammonium fluoride is 0.5-0.9g, the synthesized product is a pure Cu3N phase. Figure 2 It can be seen that under the condition of annealing time of 2h, when the annealing temperature is 300℃, the obtained product has only obvious diffraction peak of Cu3N; when the annealing temperature is 350 and 400℃, in addition to the diffraction peak of Cu3N, there is obviously the diffraction peak of Cu; on the contrary, when the annealing temperature is 250℃, in addition to the diffraction peak of Cu3N, there are also diffraction peaks of other substances; this shows that when the annealing temperature is 300℃, the pure Cu3N phase can be prepared. Figure 3It can be seen that when the annealing temperature is 300℃ and the annealing time is 2h, the obtained product has only obvious diffraction peaks of Cu3N; when the annealing time is 3h, in addition to the diffraction peaks of Cu3N, there are also diffraction peaks of Cu; on the contrary, when the annealing time is 1h, in addition to the diffraction peaks of Cu3N, there are also diffraction peaks of other substances; this shows that when the annealing temperature is 300℃ and the annealing time is 2h, a pure Cu3N phase can be prepared. Figure 4 It can be seen that when the addition amounts of copper acetylacetonate and ammonium fluoride are 0.8 g and 0.7 g respectively, after annealing at 300°C for 2 h, the obtained product is in the form of nanoparticles, some of which have an incomplete cubic structure, and the particle sizes vary, ranging from about 30 to 300 nm. Figure 5 It can be seen that when the Cu3N nanomaterial is used as a sodium ion battery electrode material for cyclic voltammetry testing, the cycle curves from the second cycle to the third cycle are basically overlapped, indicating that it has stable electrochemical performance. Figure 6 It can be seen that the initial discharge specific capacity of Cu3N nanomaterials can reach 593.6 mAh / g at 0.2 A / g, and even after 100 cycles, the specific capacity is still 254.3 mAh / g. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is the X-ray diffraction pattern of the product obtained when different amounts of ammonium fluoride are added;

[0016] Figure 2 is the X-ray diffraction pattern of the product obtained at different annealing temperatures;

[0017] Figure 3 is the X-ray diffraction pattern of the product obtained at different annealing times;

[0018] Figure 4 is a scanning electron microscope image of the product obtained in Implementation Option 2;

[0019] Figure 5 is a CV curve diagram of the product obtained in Implementation Option 2;

[0020] Figure 6 It is a cycle curve diagram of the product obtained by implementation scheme 2. DETAILED DESCRIPTION

[0021] 1. In a ceramic ark with a length and width of 45*22mm, first spread 0.5g of ammonium fluoride powder on the bottom of the ceramic ark, then spread 0.8g of copper acetylacetonate powder on the ammonium fluoride powder, and then cover it with another empty ceramic ark of the same specification; then place the ceramic ark in a tube furnace, introduce argon at a ventilation rate of 24sccm, then increase the temperature from 28℃ to 300℃ at a rate of 4℃ / min, and keep it warm for 2h, then cool it down to room temperature with the furnace, and then you can get Cu3N nanomaterials (see Figure 1 1 / 4.43 of the total).

[0022] 2. In a ceramic ark with a length and width of 45*22mm, first spread 0.7g of ammonium fluoride powder on the bottom of the ceramic ark, then spread 0.8g of copper acetylacetonate powder on the ammonium fluoride powder, and then cover it with another empty ceramic ark of the same specification; then place the ceramic ark in a tube furnace, introduce argon at a ventilation rate of 24sccm, then increase the temperature from 28℃ to 300℃ at a rate of 4℃ / min, and keep it warm for 2h, then cool it down to room temperature with the furnace, and then you can get Cu3N nanomaterials (see Figure 1 1 / 6.2 of Figure 2 300℃, Figure 3 2h and Figure 4 ).

[0023] 3. In a ceramic ark with a length and width of 45*22mm, first spread 0.9g of ammonium fluoride powder on the bottom of the ceramic ark, then spread 0.8g of copper acetylacetonate powder on the ammonium fluoride powder, and then cover it with another empty ceramic ark of the same specification; then place the ceramic ark in a tube furnace, introduce argon at a ventilation rate of 24sccm, then increase the temperature from 28℃ to 300℃ at a rate of 4℃ / min, and keep it warm for 2h, then cool it down to room temperature with the furnace, and then you can get Cu3N nanomaterials (see Figure 1 1 / 7.97 of the total).

[0024] 4. In a ceramic ark with a length and width of 45*22mm, first spread 0.7g of ammonium fluoride powder on the bottom of the ceramic ark, then spread 0.8g of copper acetylacetonate powder on the ammonium fluoride powder, and then cover it with another empty ceramic ark of the same specification; then place the ceramic ark in a tube furnace, introduce argon at a ventilation rate of 24sccm, then increase the temperature from 28℃ to 250℃ at a rate of 4℃ / min, and keep it warm for 2h, then cool it down to room temperature with the furnace, and the product can be obtained (see Figure 2 250℃ in the test tube).

[0025] 5. In a ceramic ark with a length and width of 45*22mm, first spread 0.7g of ammonium fluoride powder on the bottom of the ceramic ark, then spread 0.8g of copper acetylacetonate powder on the ammonium fluoride powder, and then cover it with another empty ceramic ark of the same specification; then place the ceramic ark in a tube furnace, introduce argon at a ventilation rate of 24sccm, then increase the temperature from 28℃ to 350℃ at a rate of 4℃ / min, and keep it warm for 2h, then cool it down to room temperature with the furnace, and the product can be obtained (see Figure 2 350℃ in the oven).

[0026] 6. In a ceramic ark with a length and width of 45*22mm, first spread 0.7g of ammonium fluoride powder on the bottom of the ceramic ark, then spread 0.8g of copper acetylacetonate powder on the ammonium fluoride powder, and then cover it with another empty ceramic ark of the same specification; then place the ceramic ark in a tube furnace, introduce argon at a ventilation rate of 24sccm, then increase the temperature from 28℃ to 400℃ at a rate of 4℃ / min, and keep it warm for 2h, then cool it down to room temperature with the furnace, and the product can be obtained (see Figure 2 400℃ in the range of 400℃).

[0027] 7. In a ceramic ark with a length and width of 45*22mm, first spread 0.7g of ammonium fluoride powder on the bottom of the ceramic ark, then spread 0.8g of copper acetylacetonate powder on the ammonium fluoride powder, and then cover it with another empty ceramic ark of the same specification; then place the ceramic ark in a tube furnace, introduce argon at a ventilation rate of 24sccm, then increase the temperature from 28℃ to 300℃ at a rate of 4℃ / min, and keep it warm for 1h, then cool it down to room temperature with the furnace, and the product can be obtained (see Figure 3 1h in the test).

[0028] 8. In a ceramic ark with a length and width of 45*22mm, first spread 0.7g of ammonium fluoride powder on the bottom of the ceramic ark, then spread 0.8g of copper acetylacetonate powder on the ammonium fluoride powder, and then cover it with another empty ceramic ark of the same specification; then place the ceramic ark in a tube furnace, introduce argon at a ventilation rate of 24sccm, then increase the temperature from 28℃ to 300℃ at a rate of 4℃ / min, and keep it warm for 3h, then cool it down to room temperature with the furnace, and the product can be obtained (see Figure 3 3h in the test).

Claims

1. A method for preparing Cu3N nanomaterial for sodium electricity, characterized in that: The following steps are involved: a) Add ammonium fluoride and copper acetylacetonate into a ceramic ark with a length and width of 45*22 mm, and then cover it with another empty ceramic ark of the same specification; b) The ceramic ark is placed in a tubular furnace, argon gas is continuously introduced at a ventilation rate of 24 sccm, and the temperature is raised from room temperature to a predetermined temperature at a heating rate of 4°C / min. After a period of heat preservation, the temperature is cooled down to room temperature along with the furnace, thereby obtaining a Cu3N nanomaterial. In the step a), the ammonium fluoride powder is spread on the bottom of the ceramic ark, and the copper acetylacetonate powder is spread on the ammonium fluoride powder.

2. The method for preparing a Cu3N nanomaterial for sodium electricity according to claim 1, characterized in that: When the amount of copper acetylacetonate added in step a) is 0.8 g, the amount of ammonium fluoride added is in the range of 0.5 to 0.9 g.

3. The method for preparing a Cu3N nanomaterial for sodium electricity according to claim 1, characterized in that: In the step b), the temperature is raised to 300° C. at a heating rate of 4° C. / min under the condition that the argon gas ventilation rate is 24 sccm, and the temperature is kept at this temperature for 2 hours.

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