Transition metal sulfur selenide for carbon-free electrode, preparation method of transition metal sulfur selenide and application of transition metal sulfur selenide in sodium-ion battery

Abstract

The invention discloses a transition metal sulfur selenide for a carbon-free electrode, a preparation method and application of the transition metal sulfur selenide in a sodium-ion battery, and belongs to the technical field of sodium-ion battery electrode materials. The preparation method comprises the following steps: grinding iron powder, sublimed sulfur and selenium powder in a mortar to obtain a thoroughly and uniformly mixed precursor mixture; transferring into a quartz tube, and then vacuumizing to a vacuum state; placing the quartz tube in a muffle furnace, sintering at 600-700 DEG C for 10-15 hours, and cooling to room temperature; and finally, grinding the obtained product to obtain the transition metal sulfur selenide for the carbon-free electrode. The prepared transition metal sulfur selenide for the carbon-free electrode can be directly synthesized through a simple solid-phase reaction; the electrode material has good electrochemical performance under the room temperature condition, and the excellent cycling stability shows the application prospects of different scenes; the preparation method is simple, low in cost and beneficial to batch production.

Description

Technical Field

[0001] The present invention belongs to the technical field of sodium-ion battery electrode materials, and particularly relates to a transition metal sulfoselenide for carbon-free electrodes, a preparation method thereof, and an application thereof in sodium-ion batteries. Background Art

[0002] As the core component of secondary batteries, the development of electrode materials has made remarkable breakthroughs since LiCoO2 first demonstrated electrochemical energy storage characteristics. Current mainstream research mainly focuses on improving the mass capacity index of materials. However, in application scenarios such as microelectronic devices, aerospace equipment, and electric vehicles, the volume energy density of battery systems is often more practically significant than the mass energy density. Especially in special fields such as space-constrained military equipment and implantable medical devices, the compact battery design poses strict requirements on the volume capacity of electrode materials. It is worth noting that this design criterion also applies to the emerging sodium-ion battery system, and the optimization of its volume energy density will directly determine the competitiveness of this technology in high-energy-density application scenarios.

[0003] The working electrode is usually composed of active materials and electrochemically inert components such as binders and conductive additives, which usually account for 20-30% of the electrode mass ratio. The intrinsic electronic conductivity of most electrode materials is relatively low, so it is necessary to introduce a conductive carbon network to improve the rate performance and cycle stability. This strategy has obvious drawbacks: the tap density of conductive carbon is usually low, which will significantly reduce the volume specific capacity and volume energy density of the electrode. Therefore, designing electrode materials with high conductivity, avoiding the use of conductive additives, designing carbon-free electrodes, and increasing the tap density of the electrodes will be of great value for improving the volume specific capacity of energy storage batteries. Summary of the Invention

[0004] Aiming at the above problems, the purpose of the present invention is to provide a transition metal sulfoselenide for carbon-free electrodes, a preparation method thereof, and an application thereof in sodium-ion batteries, and the transition metal sulfoselenide has the characteristics of high capacity.

[0005] A transition metal sulfoselenide FeSSe for carbon-free electrodes according to the present invention 0.5 The preparation method thereof comprises the following steps: (1) Weigh iron powder, sublimed sulfur, and selenium powder according to the stoichiometric ratio of 1:1.05:1, and then grind them in a mortar to obtain a thoroughly mixed precursor mixture; (2) Transfer the precursor mixture obtained in step (1) to a quartz tube, and then evacuate the quartz tube to a vacuum state; (3) Place the quartz tube in step (2) in a muffle furnace, sinter it at 600-700 °C for 10-15 hours, and then cool it to room temperature; (4) Grinding the product obtained in step (3) to obtain the transition metal sulfide selenide FeSSe for carbon-free electrode 0.5 .

[0006] Furthermore, the grinding time in step (1) is 15 to 30 minutes to ensure complete and uniform mixing; Furthermore, the quartz tube in step (3) is placed in a muffle furnace and programmed to heat up from room temperature to 600-700°C at a rate of 3-6°C / min; Furthermore, the grinding time in step (4) is 15 to 30 minutes, so that the block is completely transformed into powder.

[0007] The present invention relates to a transition metal sulfide selenide FeSSe for carbon-free electrodes. 0.5 , which is prepared by the above method.

[0008] The present invention relates to a transition metal sulfide selenide FeSSe for carbon-free electrodes. 0.5 It can be used in sodium-ion batteries.

[0009] The prepared transition metal sulfide selenide FeSSe for carbon-free electrode 0.5 As the battery active material, Super P is used as a conductive agent and carboxymethyl cellulose is used as a binder. They are weighed in a mass ratio of 7:2:1 and ground into a paste using ultrapure water as a solvent. They are then evenly coated on a copper foil current collector. After drying, they are used as the working electrode of a sodium ion battery and assembled with metallic sodium and an organic electrolyte into a sodium ion half-cell as a control group with a carbon electrode.

[0010] The prepared transition metal sulfide selenide FeSSe for carbon-free electrode 0.5 As the battery active material, carboxymethyl cellulose was used as a binder, weighed at a mass ratio of 29:1, and ground into a paste using ultrapure water as a solvent. It was then evenly coated on a copper foil current collector. After drying, it was used as a carbon-free working electrode for a sodium-ion battery and assembled with a metal sodium counter electrode and an organic electrolyte to form a sodium-ion half-cell as a carbon-free electrode experimental group.

[0011] The beneficial effects of the present invention are: 1) Transition metal sulfide selenide FeSSe prepared by the present invention for carbon-free electrode 0.5 , can be directly synthesized through a simple solid-phase reaction; 2) The present invention prepares the transition metal sulfide selenide FeSSe for carbon-free electrode 0.5Electrochemical performance tests were carried out on sodium-ion batteries. The experimental results show that the electrode material has good electrochemical performance at room temperature. With Super P providing electronic conductivity, the battery has a high discharge specific capacity of 527.8 mAh g -1 after 100 cycles; without Super P providing electronic conductivity, the battery still has a discharge specific capacity of 523.98 mAh g -1 after 100 cycles; at 0 °C, the carbon-free electrode still has a high discharge specific capacity of 482.63 mAh g -1 after 100 cycles. Its excellent cycling stability demonstrates the application prospects in different scenarios; 3) The preparation method adopted in the present invention is simple and has low cost, which is conducive to mass production. Description of the Drawings

[0012] Figure 1 SEM image of the FeSSe 0.5 powder material prepared in Example 1 of the present invention, showing the particle size distribution; Figure 2 XRD pattern of the FeSSe 0.5 powder material prepared in Example 1 of the present invention; Figure 3 Element ratio bar chart of the FeSSe 0.5 powder material prepared in Example 1 of the present invention measured by ICP; Figure 4 Charge-discharge curve of the battery when the FeSSe 0.5 powder material prepared in Example 1 of the present invention is used as the active material, and at room temperature, according to the mass ratio of active material: Super P: sodium carboxymethyl cellulose = 7:2:1, the obtained electrode is applied to a sodium-ion battery at a current density of 0.1 A g -1 ; Figure 5 Cycle performance graph of the battery when the FeSSe 0.5 powder material prepared in Example 1 of the present invention is used as the active material, and at room temperature, according to the mass ratio of active material: Super P: sodium carboxymethyl cellulose = 7:2:1, the obtained electrode is applied to a sodium-ion battery at a current density of 0.5 A g -1 ; Figure 6 Charge-discharge curve of the battery when the FeSSe 0.5 powder material prepared in Example 1 of the present invention is used as the active material, and at room temperature, according to the mass ratio of active material: sodium carboxymethyl cellulose = 29:1, the obtained electrode is applied to a carbon-free sodium-ion battery at a current density of 0.1 A g -1 ; Figure 7 The FeSSe prepared in Example 1 of the present invention 0.5 As the active material, the powder material is used. At room temperature, according to the mass ratio of active material: sodium carboxymethyl cellulose = 29:1, the obtained electrode is applied to a carbon-free sodium-ion battery at a current density of 0.2 A g -1 The charge-discharge curve of the battery under; Figure 8 The FeSSe prepared in Example 1 of the present invention 0.5 As the active material, the powder material is used. At room temperature, according to the mass ratio of active material: sodium carboxymethyl cellulose = 29:1, the obtained electrode is applied to a carbon-free sodium-ion battery at a current density of 0.5 A g -1 The charge-discharge curve of the battery under; Figure 9 The FeSSe prepared in Example 1 of the present invention 0.5 As the active material, the powder material is used. At room temperature, according to the mass ratio of active material: sodium carboxymethyl cellulose = 29:1, the obtained electrode is applied to a carbon-free sodium-ion battery at a current density of 0.5 A g -1 The cycle performance curve of the battery under; Figure 10 The FeSSe prepared in Example 1 of the present invention 0.5 As the active material, the powder material is used. At room temperature, according to the mass ratio of active material: sodium carboxymethyl cellulose = 29:1, the obtained positive electrode is applied to a carbon-free sodium-ion battery at a current density of 1 A g -1 The cycle performance curve of the battery under; Figure 11 The FeSSe prepared in Example 1 of the present invention 0.5 As the active material, the powder material is used. At 0 °C, according to the mass ratio of active material: sodium carboxymethyl cellulose = 29:1, the obtained electrode is applied to a carbon-free sodium-ion battery at a current density of 0.1 A g -1 The charge-discharge curve of the battery under; Figure 12 The FeSSe prepared in Example 1 of the present invention 0.5 As the active material, the powder material is used. At 0 °C, according to the mass ratio of active material: sodium carboxymethyl cellulose = 29:1, the obtained electrode is applied to a carbon-free sodium-ion battery at a current density of 0.1 A g -1 The cycle performance curve of the battery under. Detailed implementation mode

[0013] Example 1: (1) Iron powder (purity > 99.5%, Aladdin), sublimed sulfur (purity > 99.5%, Aladdin) and selenium powder (purity > 99.95%, 200 mesh, Aladdin) were weighed in a stoichiometric ratio of 1:1.05:1, i.e., 0.1657 g of iron powder, 0.1 g of sublimed sulfur and 0.2343 g of selenium powder, and then ground in a mortar for 20 minutes to obtain a thoroughly mixed powder mixture; (2) transferring the precursor mixture obtained in step (1) into a quartz tube and evacuating the tube to a vacuum state; (3) Place the quartz tube in step (2) in a muffle furnace, and heat it from room temperature to 650°C at a rate of 5°C per minute, and then cool it down to room temperature after sintering for 12 hours; (4) Grind the product obtained in step (3) for 20 minutes to completely change it from a block to a powder to obtain transition metal sulfide selenide FeSSe 0.5 .

[0014] like Figure 1 The image shown is a scanning electron microscope image of the sample prepared in Example 1, and the particle size is 2-10 μm; like Figure 2 Shown is the X-ray powder diffraction test pattern of the sample prepared in Example 1; like Figure 3 The results of the inductively coupled plasma test of the sample prepared in Example 1 are shown. The results show that the molecular formula of the obtained material is FeSSe 0.5 The horizontal axis in the figure is the element name, the vertical axis is the molar ratio of the element in the material, and the error bar shows the range of the three test results.

[0015] Example 2: The transition metal sulfide selenide FeSSe prepared in Example 1 0.5 As the battery active material, Super P as a conductive agent, sodium carboxymethyl cellulose as a binder, weighed at a mass ratio of 7:2:1, and ground into a paste with ultrapure water as a solvent, FeSSe 0.5 The concentration of the electrolyte was 33% (mass ratio); it was then evenly coated on a copper foil current collector. After drying, it was used as a sodium ion battery working electrode and assembled with a metal sodium counter electrode and an organic electrolyte to form a button-type sodium ion half-cell as a control group with a carbon electrode. The drying time is 8 hours, and it can be dried in a fume hood; The sodium ion battery assembled under inert gas conditions was left to stand at room temperature for 2 hours before starting electrochemical performance testing at room temperature, as in Test Examples 1 and 2.

[0016] Test Example 1: At room temperature, the electrochemical performance test conditions of the button-type sodium-ion battery assembled in Example 2 are as follows: the current density used for battery testing is 0.1 A g -1 , the voltage range is 0.1~3.0 V. A layer of GF / C separator is used and placed between the working electrode and the counter electrode of the battery to prevent direct contact between the two from causing a short circuit. The electrolyte is a DME solution of 1 M NaPF6. The charge-discharge specific capacity diagram of the first five cycles of the battery is as shown in Figure 4 . The abscissa represents the discharge specific capacity, and the ordinate represents the voltage. The electrochemical performance test of the battery is carried out in a Wuhan Blue Electric battery test system, indicating that under the preparation conditions of Example 2, the battery has a high discharge specific capacity of 640.66 mAh g -1 in the first cycle.

[0017] Test Example 2: At room temperature, the electrochemical performance test conditions of the button-type sodium-ion battery assembled in Example 2 are as follows: the current density used for battery testing is 0.5 A g -1 , the voltage range is 0.1~3.0 V. Two layers of GF / C separators are used and placed between the working electrode and the counter electrode of the battery to prevent direct contact between the two from causing a short circuit. The electrolyte is a DME solution of 1 M NaPF6. The cycle performance diagram of the battery is as shown in Figure 5 . The abscissa represents the number of cycles, the left ordinate represents the discharge specific capacity, and the right ordinate represents the Coulomb efficiency. The electrochemical performance test of the battery is carried out in a Wuhan Blue Electric battery test system, indicating that under the preparation conditions of Example 2, the battery has good cycle retention and high discharge specific capacity. After 100 cycles, it still maintains good cycle performance and has a high discharge specific capacity of 527.8 mAh g -1

[0018] Example 3: The transition metal sulfoselenide FeSSe prepared in Example 1 0.5 is used as the battery active material, and sodium carboxymethyl cellulose is used as the binder. They are weighed in a mass ratio of 29:1, and ultrapure water is used as the solvent to grind them into a paste. The concentration of FeSSe 0.5 is 33% (mass ratio); then it is evenly coated on a copper foil current collector. After drying, it is used as the working electrode of the sodium-ion battery and assembled with a sodium metal counter electrode and an organic electrolyte into a sodium-ion half-cell, serving as the carbon-free electrode experimental group; The drying time is 8 hours, and it can be dried in a fume hood; For the sodium-ion battery assembled under inert gas conditions, after standing at room temperature for 2 hours, the electrochemical performance test at room temperature is started, such as Test Examples 3~6.

[0019] Test Example 3: Under room temperature conditions, the electrochemical performance test conditions of the button-type sodium-ion battery assembled in Example 3 are as follows: the current density used for battery testing is 0.1 A g -1 , the voltage range is 0.1~3.0 V. Two layers of GF / C diaphragms are used and placed between the working electrode and the counter electrode of the battery to prevent direct contact between the two from causing a short circuit. The electrolyte is a DME solution of 1 M NaPF6. The charge-discharge specific capacity diagram of the first five cycles of the battery is as shown in Figure 6 . The abscissa represents the discharge specific capacity, and the ordinate represents the voltage. The electrochemical performance test of the battery is carried out in a Wuhan Blue Electric battery test system, indicating that under the preparation conditions of Example 3, the battery has a high discharge specific capacity, and the first-cycle discharge specific capacity is 564.21 mAh g -1 .

[0020] Test Example 4: Under room temperature conditions, the electrochemical performance test conditions of the button-type sodium-ion battery assembled in Example 3 are as follows: the current density used for battery testing is 0.2 A g -1 , the voltage range is 0.1~3.0 V. Two layers of GF / C diaphragms are used and placed between the working electrode and the counter electrode of the battery to prevent direct contact between the two from causing a short circuit. The electrolyte is a DME solution of 1 M NaPF6. The charge-discharge specific capacity diagram of the first five cycles of the battery is as shown in Figure 7 . The abscissa represents the discharge specific capacity, and the ordinate represents the voltage. The electrochemical performance test of the battery is carried out in a Wuhan Blue Electric battery test system, indicating that under the preparation conditions of Example 3, the battery has a high discharge specific capacity, and the first-cycle discharge specific capacity is 536.24 mAh g -1 .

[0021] Test Example 5: Under room temperature conditions, the electrochemical performance test conditions of the button-type sodium-ion battery assembled in Example 3 are as follows: the current density used for battery testing is 0.5 A g -1 , the voltage range is 0.1~3.0 V. Two layers of GF / C diaphragms are used and placed between the working electrode and the counter electrode of the battery to prevent direct contact between the two from causing a short circuit. The electrolyte is a DME solution of 1 M NaPF6. The charge-discharge specific capacity diagram of the first five cycles of the battery is as shown in Figure 8 . The abscissa represents the discharge specific capacity, and the ordinate represents the voltage. The battery cycle performance diagram is as shown in Figure 9 . The abscissa represents the number of cycles, the left ordinate represents the discharge specific capacity, and the right ordinate represents the Coulomb efficiency. The electrochemical performance test of the battery is carried out in a Wuhan Blue Electric battery test system. After 100 cycles, it still has a high discharge specific capacity of 523.98 mAh g -1 , indicating that under the preparation conditions of Example 3, the battery has good cycle stability.

[0022] Test Example 6: Under room temperature conditions, the electrochemical performance test conditions of the button-type sodium-ion battery assembled in Example 3 are as follows: The current density used for battery testing is 1 A g -1 , the voltage range is 0.1~3.0 V. Two layers of GF / C separators are used and placed between the working electrode and the counter electrode of the battery to prevent short circuit caused by direct contact between the two. The electrolyte is a DME solution of 1 M NaPF6. The battery cycle performance diagram is as shown in Figure 10 . The abscissa represents the number of cycles, the left ordinate represents the discharge specific capacity, and the right ordinate represents the Coulomb efficiency. The electrochemical performance test of the battery is carried out in a Wuhan Blue Electric battery test system. After 100 cycles, it still has a high discharge specific capacity of 552.70 mAh g -1 , indicating that under the preparation conditions of Example 3, the battery has good cycle stability.

[0023] Example 4: The transition metal sulfoselenide FeSSe prepared in Example 1 0.5 is used as the battery active material, and sodium carboxymethyl cellulose is used as the binder. They are weighed in a mass ratio of 29:1, and ultrapure water is used as the solvent to grind into a paste. The concentration of FeSSe 0.5 is 33%; it is evenly coated on a copper foil current collector. After drying, it is used as the working electrode of the sodium-ion battery and assembled with a sodium metal counter electrode and an organic electrolyte into a sodium-ion half-cell, serving as the carbon-free electrode experimental group; The drying time is 8 hours, and it can be dried in a fume hood; The sodium-ion battery assembled under inert gas conditions is left standing at room temperature for 6 hours, and then left standing in a constant temperature oven at 0 °C for 6 hours, and then the electrochemical performance test under 0 °C conditions is started, as in Test Example 7.

[0024] Test Example 7: Under 0 °C conditions, the electrochemical performance test conditions of the assembled button-type sodium-ion battery are as follows: The current density used for battery testing is 0.1 A g -1 , the voltage range is 0.1~3.0 V. Two layers of GF / C separators are used and placed between the working electrode and the counter electrode of the battery to prevent short circuit caused by direct contact between the two. The electrolyte is a DME solution of 1 M NaPF6. The first five charge-discharge specific capacity diagrams of the battery are as shown in Figure 11 . The abscissa represents the discharge specific capacity, and the ordinate represents the voltage. The battery cycle performance diagram is as shown in Figure 12As shown, the abscissa represents the number of cycles, the left ordinate represents the discharge specific capacity, and the right ordinate represents the Coulombic efficiency. The electrochemical performance test of the battery was carried out in a Wuhan Blue Electric battery test system, indicating that under the preparation conditions of Example 4, even after 100 cycles at 0 °C, it still has a high discharge specific capacity of 482.63 mAh g -1 , and is as stable as the carbon-containing electrode prepared in Example 2 at room temperature, and the battery has good cycle stability.

[0025] Under the application of sodium-ion batteries, the high-capacity carbon-free electrode prepared by the method of the present invention can achieve a high discharge specific capacity that most sulfur-selenium metal compounds cannot reach without using a conductive additive, reducing the usage amount of carbon without electrochemical activity, and is expected to improve the volumetric specific capacity.

[0026] Finally, it should be noted that the above is only used to illustrate the technical solution of the present invention and not to limit it. Any other modifications or equivalent replacements made by those of ordinary skill in the art to the technical solution of the present invention should be covered within the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A transition metal sulfoselenide FeSSe for carbon-free electrodes 0.5 The preparation method is characterized in that: The steps are as follows: (1) Iron powder, sublimed sulfur, and selenium powder were weighed in a stoichiometric ratio of 1:1.05:1 and then ground in a mortar to obtain a thoroughly mixed precursor mixture; (2) transferring the precursor mixture obtained in step (1) into a quartz tube, and then evacuating the quartz tube to a vacuum state; (3) placing the quartz tube in step (2) in a muffle furnace, sintering at 600-700°C for 10-15 hours and then cooling to room temperature; (4) Grind the product obtained in step (3) to obtain the transition metal sulfoselenide FeSSe for carbon-free electrodes 0.5 .

2. The preparation method of a transition metal sulfoselenide FeSSe for a carbon-free electrode according to claim 1 0.5 , characterized in that: The grinding time in step (1) is 15 to 30 minutes to ensure complete and uniform mixing.

3. A preparation method of transition metal sulfoselenide FeSSe for carbon-free electrodes according to claim 1 0.5 , characterized in that: The quartz tube in step (3) is placed in a muffle furnace and programmed to heat up from room temperature to 600-700°C at a rate of 3-6°C / min.

4. A preparation method of transition metal sulfoselenide FeSSe for carbon-free electrodes as described in claim 1 0.5 , characterized in that: The grinding time in step (4) is 15 to 30 minutes, so that the block is completely transformed into powder.

5. A transition metal sulfoselenide FeSSe for carbon-free electrodes 0.5 , characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 4.

6. Application of the transition metal sulfoselenide FeSSe for a carbon-free electrode as claimed in claim 5 0.5 in a sodium ion battery.

7. Application of transition metal sulfoselenide FeSSe for carbon-free electrode as claimed in claim 6 0.5 in a sodium-ion battery, characterized in that: The prepared transition metal sulfide selenide for carbon-free electrode is used as the battery active material, carboxymethyl cellulose is used as a binder, weighed at a mass ratio of 29:1, and ground into a paste using ultrapure water as a solvent; it is then evenly coated on a copper foil current collector. After drying, it is used as the carbon-free working electrode of the sodium ion battery and assembled with a metal sodium counter electrode and an organic electrolyte to form a sodium ion half-cell.

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