A transition metal sulfide selenide for carbon-free electrode, preparation method and application in sodium ion battery

Abstract

A transition metal selenide sulfide for a carbon-free electrode, a preparation method, and its application in sodium-ion batteries belong to the technical field of sodium-ion battery electrode materials. The method comprises grinding iron powder, sublimed sulfur, and selenium powder in a mortar to obtain a thoroughly mixed precursor mixture; transferring the mixture to a quartz tube and evacuating it to a vacuum state; placing the quartz tube in a muffle furnace, sintering it at 600-700°C for 10-15 hours, and then cooling it to room temperature; and finally grinding the obtained product to obtain the transition metal selenide sulfide for a carbon-free electrode. The transition metal selenide sulfide for a carbon-free electrode prepared by the present invention can be directly synthesized via a simple solid-phase reaction; the electrode material has good electrochemical properties at room temperature, and its excellent cycle stability demonstrates application prospects in various scenarios; the preparation method adopted by the present invention is simple and low-cost, which is conducive to mass 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 sulfide selenide for a carbon-free electrode, a preparation method and application thereof in a sodium ion battery. Background Art

[0002] As the core component of secondary batteries, the development of electrode materials has made significant breakthroughs since LiCoO2 first demonstrated its electrochemical energy storage properties. Current mainstream research focuses on improving the mass capacity indicators of materials. However, in application scenarios such as microelectronics, aerospace equipment, and electric vehicles, the volume energy density of the battery system is often more practical than the mass energy density. Especially in special fields such as space-constrained military equipment and implantable medical devices, compact battery design places stringent requirements on the volume capacity of electrode materials. It is worth noting that this design criterion also applies to emerging sodium-ion battery systems, 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. Most electrode materials have low intrinsic electronic conductivity, so it is necessary to introduce a conductive carbon network to improve rate performance and cycle stability. This strategy has obvious drawbacks: the tap density of conductive carbon is usually low, which will greatly reduce the volumetric capacity and volumetric 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 electrode will be of great value in improving the volumetric capacity of energy storage batteries. Summary of the Invention

[0004] In view of the above problems, the purpose of the present invention is to provide a transition metal sulfide selenide for carbon-free electrodes, a preparation method and its application in sodium ion batteries, wherein the transition metal sulfide selenide has the characteristics of high capacity.

[0005] The present invention relates to a transition metal sulfide selenide FeSSe for carbon-free electrodes. 0.5 The preparation method comprises the following steps:

[0006] (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;

[0007] (2) transferring the precursor mixture obtained in step (1) into a quartz tube, and then evacuating the quartz tube to a vacuum state;

[0008] (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;

[0009] (4) Grinding the product obtained in step (3) to obtain the transition metal sulfide selenide FeSSe for carbon-free electrode 0.5 .

[0010] Furthermore, the grinding time in step (1) is 15 to 30 minutes to ensure complete and uniform mixing;

[0011] 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;

[0012] Furthermore, the grinding time in step (4) is 15 to 30 minutes, so that the block is completely transformed into powder.

[0013] The present invention relates to a transition metal sulfide selenide FeSSe for carbon-free electrodes. 0.5 , which is prepared by the above method.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] The beneficial effects of the present invention are:

[0018] 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;

[0019] 2) The present invention prepares the transition metal sulfide selenide FeSSe for carbon-free electrode 0.5 The electrochemical performance test of sodium ion battery was carried out. The experimental results showed that the electrode material has good electrochemical performance at room temperature. In the case of Super P to provide electronic conductivity, the battery has a capacity of 527.8 mAh g after 100 cycles. -1 High discharge capacity; without Super P to provide electronic conductivity, the battery still has 523.98 mAh g after 100 cycles. -1 The discharge capacity of the carbon-free electrode is 482.63 mAh g after 100 cycles at 0°C. -1 Its high discharge capacity and excellent cycle stability demonstrate its application prospects in different scenarios;

[0020] 3) The preparation method adopted by the present invention is simple and low in cost, which is conducive to mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 FeSSe prepared in Example 1 of the present invention 0.5 SEM image of the powder material showing the particle size distribution;

[0022] Figure 2 FeSSe prepared in Example 1 of the present invention 0.5 XRD pattern of powder material;

[0023] Figure 3 The FeSSe prepared in Example 1 of the present invention was measured by ICP. 0.5 Element ratio bar chart of powder material;

[0024] Figure 4 FeSSe prepared in Example 1 of the present invention 0.5 The powder material was used as the active material, and the mass ratio of active material: Super P: sodium carboxymethyl cellulose = 7:2:1 was used to prepare the electrode for sodium ion battery at a current density of 0.1 A g -1 The battery charge and discharge curve below;

[0025] Figure 5 FeSSe prepared in Example 1 of the present invention 0.5 The powder material was used as the active material, and the mass ratio of active material: Super P: sodium carboxymethyl cellulose = 7:2:1 was used to prepare the electrode for sodium ion battery at a current density of 0.5 A g -1 The battery cycle performance diagram below;

[0026] Figure 6 FeSSe prepared in Example 1 of the present invention 0.5 The powder material was used as the active material, and the mass ratio of active material to sodium carboxymethyl cellulose was 29:1 at room temperature. The obtained electrode was used in carbon-free sodium ion batteries at a current density of 0.1 A g -1 The battery charge and discharge curve below;

[0027] Figure 7 FeSSe prepared in Example 1 of the present invention 0.5 The powder material was used as the active material, and the mass ratio of active material to sodium carboxymethyl cellulose was 29:1 at room temperature. The obtained electrode was used in carbon-free sodium ion batteries at a current density of 0.2 A g -1 The battery charge and discharge curve below;

[0028] Figure 8 FeSSe prepared in Example 1 of the present invention 0.5 The powder material was used as the active material, and the mass ratio of active material to sodium carboxymethyl cellulose was 29:1 at room temperature. The obtained electrode was used in carbon-free sodium ion batteries at a current density of 0.5 A g -1 The battery charge and discharge curve below;

[0029] Figure 9 FeSSe prepared in Example 1 of the present invention 0.5 The powder material was used as the active material, and the mass ratio of active material to sodium carboxymethyl cellulose was 29:1 at room temperature. The obtained electrode was used in a carbon-free sodium ion battery at a current density of 0.5A g -1 Battery cycle performance curve under

[0030] Figure 10 FeSSe prepared in Example 1 of the present invention 0.5 The powder material was used as the active material, and the mass ratio of active material to sodium carboxymethyl cellulose was 29:1 at room temperature. The obtained positive electrode was applied to carbon-free sodium ion batteries at a current density of 1A g -1 Battery cycle performance curve under

[0031] Figure 11 FeSSe prepared in Example 1 of the present invention 0.5 The powder material was used as the active material, and the mass ratio of active material to sodium carboxymethyl cellulose was 29:1 at 0°C. The obtained electrode was used in a carbon-free sodium ion battery at a current density of 0.1 A g -1 The battery charge and discharge curve below;

[0032] Figure 12 FeSSe prepared in Example 1 of the present invention 0.5The powder material was used as the active material, and the mass ratio of active material to sodium carboxymethyl cellulose was 29:1 at 0°C. The obtained electrode was used in a carbon-free sodium ion battery at a current density of 0.1 A g -1 The battery cycle performance curve below. DETAILED DESCRIPTION

[0033] Example 1:

[0034] (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;

[0035] (2) transferring the precursor mixture obtained in step (1) into a quartz tube and evacuating the tube to a vacuum state;

[0036] (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;

[0037] (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 .

[0038] 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;

[0039] like Figure 2 Shown is the X-ray powder diffraction test pattern of the sample prepared in Example 1;

[0040] 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.

[0041] Example 2:

[0042] 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, FeSSe0.5 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.

[0043] The drying time is 8 hours, and it can be dried in a fume hood;

[0044] 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.

[0045] Test Example 1:

[0046] Under room temperature conditions, the electrochemical performance test conditions of the button-type sodium ion battery assembled in Example 2 are as follows: the current density used in the battery test is 0.1A g -1 The voltage range is 0.1~3.0V. A layer of GF / C diaphragm is placed between the working electrode and the counter electrode of the battery to prevent direct contact between the two and cause a short circuit. The electrolyte is a 1 M NaPF6 DME solution. The charge and discharge capacity of the battery in the first five cycles is shown in the figure. Figure 4 As shown, the abscissa represents the discharge capacity, and the ordinate represents the voltage. The electrochemical performance test of the battery was carried out in the Wuhan Blue Electric Battery Test System, which showed that under the preparation conditions of Example 2, the battery had a first cycle capacity of 640.66 mAh g -1 High discharge capacity.

[0047] Test Example 2:

[0048] Under room temperature conditions, the electrochemical performance test conditions of the button-type sodium ion battery assembled in Example 2 are as follows: the current density used in the battery test is 0.5 A g -1 The voltage range is 0.1~3.0V. Two layers of GF / C diaphragm are placed between the working electrode and the counter electrode of the battery to prevent direct contact between the two and cause short circuit. The electrolyte is 1 M NaPF6 DME solution. The battery cycle performance diagram is shown in the figure. Figure 5 As shown, the horizontal axis represents the number of cycles, the left vertical axis represents the discharge specific capacity, and the right vertical axis represents the coulombic efficiency. The electrochemical performance test of the battery was carried out in the Wuhan Blue Electric Battery Test System, which showed that under the preparation conditions of Example 2, the battery had good cycle retention rate and high discharge specific capacity. After 100 cycles, it still maintained good cyclability and had a capacity of 527.8 mAh g -1 High discharge capacity.

[0049] Example 3:

[0050] The transition metal sulfide selenide FeSSe prepared in Example 10.5 As the battery active material, sodium carboxymethyl cellulose was used as a binder, weighed at a mass ratio of 29:1, ground into a paste with ultrapure water as a solvent, and FeSSe 0.5 The concentration of the electrolyte was 33% (mass ratio); it was then evenly coated on a copper foil current collector and, after drying, used as a sodium ion battery working electrode, 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;

[0051] The drying time is 8 hours, and it can be dried in a fume hood;

[0052] The sodium ion batteries assembled under inert gas conditions were left standing at room temperature for 2 hours before electrochemical performance tests were performed at room temperature, such as Test Examples 3 to 6.

[0053] Test Example 3:

[0054] 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 in the battery test is 0.1 A g -1 The voltage range is 0.1~3.0V. Two layers of GF / C diaphragm are placed between the working electrode and the counter electrode of the battery to prevent direct contact between the two and cause short circuit. The electrolyte is 1 M NaPF6 DME solution. The charge and discharge capacity of the battery in the first five cycles is shown in the figure. Figure 6 As shown, the abscissa represents the discharge specific capacity, and the ordinate represents the voltage. The electrochemical performance test of the battery was carried out in the Wuhan Blue Electric Battery Test System, which showed that under the preparation conditions of Example 3, the battery had a high discharge specific capacity, and the first cycle discharge specific capacity was 564.21 mAh g -1 .

[0055] Test Example 4:

[0056] 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 in the battery test is 0.2 A g -1 The voltage range is 0.1~3.0V. Two layers of GF / C diaphragm are placed between the working electrode and the counter electrode of the battery to prevent direct contact between the two and cause short circuit. The electrolyte is 1 M NaPF6 DME solution. The charge and discharge capacity of the battery in the first five cycles is shown in the figure. Figure 7 As shown, the abscissa represents the discharge specific capacity and the ordinate represents the voltage. The electrochemical performance test of the battery was carried out in the Wuhan Blue Electric Battery Test System, which showed that under the preparation conditions of Example 3, the battery had a high discharge specific capacity, and the first cycle discharge specific capacity was 536.24 mAh g -1 .

[0057] Test Example 5:

[0058] Under room temperature, the electrochemical performance test conditions of the button-type sodium ion battery assembled in Example 3 are as follows: the current density used in the battery test is 0.5 A g -1 The voltage range is 0.1~3.0V. Two layers of GF / C diaphragm are placed between the working electrode and the counter electrode of the battery to prevent direct contact between the two and cause short circuit. The electrolyte is 1 M NaPF6 DME solution. The charge and discharge capacity of the battery in the first five cycles is shown in the figure. Figure 8 As shown, the horizontal axis represents the discharge capacity, the vertical axis represents the voltage, and the battery cycle performance diagram is as follows Figure 9 As shown, the horizontal axis represents the number of cycles, the left vertical axis represents the discharge capacity, and the right vertical axis represents the Coulomb efficiency. The electrochemical performance test of the battery was carried out in the Wuhan Blue Electric Battery Test System. After 100 cycles, it still has 523.98 mAh g -1 The high discharge specific capacity indicates that under the preparation conditions of Example 3, the cycle stability of the battery is good.

[0059] Test Example 6:

[0060] 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 in the battery test is 1 A g -1 The voltage range is 0.1~3.0V. Two layers of GF / C diaphragm are placed between the working electrode and the counter electrode of the battery to prevent direct contact between the two and cause short circuit. The electrolyte is 1 M NaPF6 DME solution. The battery cycle performance diagram is shown in the figure. Figure 10 As shown, the horizontal axis represents the number of cycles, the left vertical axis represents the discharge specific capacity, and the right vertical axis represents the Coulomb efficiency. The electrochemical performance test of the battery was carried out in the Wuhan Blue Electric Battery Test System. After 100 cycles, it still has 552.70 mAh g -1 The high discharge specific capacity indicates that under the preparation conditions of Example 3, the cycle stability of the battery is good.

[0061] Example 4:

[0062] The transition metal sulfide selenide FeSSe prepared in Example 1 0.5 As the battery active material, sodium carboxymethyl cellulose was used as a binder, weighed at a mass ratio of 29:1, ground into a paste with ultrapure water as a solvent, and FeSSe 0.5 The concentration of the electrolyte was 33%; the electrolyte was evenly coated on a copper foil current collector and, after drying, used as a sodium ion battery working electrode, 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;

[0063] The drying time is 8 hours, and it can be dried in a fume hood;

[0064] The sodium ion battery assembled under inert gas conditions was left at room temperature for 6 hours and then in a 0°C thermostat for 6 hours before the electrochemical performance test at 0°C was started, as shown in Test Example 7.

[0065] Test Example 7:

[0066] At 0°C, the electrochemical performance test conditions of the assembled button sodium ion battery are as follows: the current density used for battery testing is 0.1 A g -1 The voltage range is 0.1~3.0V. Two layers of GF / C diaphragm are placed between the working electrode and the counter electrode of the battery to prevent direct contact between the two and cause short circuit. The electrolyte is 1 M NaPF6 DME solution. The charge and discharge capacity of the battery in the first five cycles is shown in the figure. Figure 11 As shown, the horizontal axis represents the discharge capacity, the vertical axis represents the voltage, and the battery cycle performance diagram is as follows Figure 12 As shown, the horizontal axis represents the number of cycles, the left vertical axis represents the discharge specific capacity, and the right vertical axis represents the coulombic efficiency. The electrochemical performance test of the battery was carried out in the Wuhan Blue Electric Battery Test System, which showed that under the preparation conditions of Example 4, even after 100 cycles at 0°C, it still had a capacity of 482.63 mAh g -1 The high discharge specific capacity is as stable as the carbon electrode prepared in Example 2 at room temperature, and the battery has good cycle stability.

[0067] 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 achieve when used in sodium ion batteries without using a conductive additive, thereby reducing the use of carbon without electrochemical activity and is expected to improve the volumetric specific capacity.

[0068] Finally, it should be noted that the above description is only used to illustrate the technical solution of the present invention and is not intended to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in this field should be included in 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 sulfide selenide 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) Grinding the product obtained in step (3) to obtain the transition metal sulfide selenide FeSSe for carbon-free electrode 0.5 .

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

3. A transition metal sulfide selenide FeSSe for a carbon-free electrode as claimed in claim 1 0.5 The preparation method is 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 transition metal sulfide selenide FeSSe for a carbon-free electrode as claimed in claim 1 0.5 The preparation method is 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 sulfide selenide 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. The transition metal sulfide selenide FeSSe for carbon-free electrodes according to claim 5 0.5 Application in sodium-ion batteries.

7. A transition metal sulfide selenide FeSSe for a carbon-free electrode as claimed in claim 6 0.5 Application in sodium ion batteries, characterized by: 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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