A porous sulfide bond functionalized carbon material and its preparation method and application

Abstract

The present invention belongs to the field of electrochemical energy storage technology, and discloses a porous sulfide bond functionalized carbon material, a preparation method and an application. The preparation method comprises: mixing sodium chloride, glucose, thiourea and water and stirring them evenly to obtain a solution A; freezing, vacuum freeze drying and grinding the solution A in sequence to obtain a precursor powder; pyrolysis carbonization treatment, washing, vacuum drying and grinding the precursor powder in sequence to obtain a porous sulfide bond functionalized carbon material. The present invention can assemble the prepared porous sulfide bond functionalized carbon material into a sodium battery as an active electrode material. The porous sulfide bond functionalized carbon material of the present invention has great application potential in safe, low-cost, high-energy and long-life (RT) Na-S batteries.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochemical energy storage, and more specifically, relates to a porous sulfide bond functionalized carbon material and a preparation method and application thereof. Background Art

[0002] As a candidate for advanced rechargeable batteries, sodium-sulfur (Na-S) batteries have potential application prospects in a wide range of grid-scale storage technologies due to their inexhaustible and low-cost raw materials. However, since traditional high-temperature Na-S batteries operate at 300-350°C and both active electrode materials are liquid, there are serious safety issues and a series of cost issues when used on a large scale. Lowering the operating temperature of Na-S batteries is conducive to improving safety issues and reducing expenses. Therefore, researchers have spared no effort to develop room-temperature (RT) Na-S batteries for electrochemical energy storage technology.

[0003] Many sulfur-doped carbons containing bound sulfur have been proposed as electrode materials with enhanced sodium storage properties, which can be attributed to the fact that the sulfur dopant enlarges the interlayer distance of carbon, thereby improving the sodium storage specific capacity. In addition, it has been reported that the covalent bond between carbon and sulfur is too strong to be easily broken under electrochemical conditions. Most studies have ignored the electrochemical activity of sulfur dopants. Therefore, it is necessary to study the effect of the electrochemical activity of bound sulfur on sodium storage.

[0004] Therefore, the present invention provides a porous sulfide bond functionalized carbon material and a preparation method and application thereof. Summary of the invention

[0005] The purpose of the present invention is to provide a porous sulfide bond functionalized carbon material, a preparation method and an application thereof in view of the deficiencies of the prior art. The present invention can assemble the prepared porous sulfide bond functionalized carbon material into a sodium battery as an active electrode material. The porous sulfide bond functionalized carbon material of the present invention has great application potential in safe, low-cost, high-energy and long-life (RT) Na-S batteries.

[0006] In order to achieve the above object, the first aspect of the present invention provides a method for preparing a porous sulfide bond functionalized carbon material, the preparation method comprising the following steps:

[0007] S1: Mix sodium chloride, glucose, thiourea and water and stir to obtain solution A;

[0008] S2: freezing, vacuum freeze-drying and grinding the solution A in sequence to obtain a precursor powder;

[0009] S3: subjecting the precursor powder to pyrolysis carbonization treatment, washing, vacuum drying and grinding in sequence to obtain the porous sulfide bond functionalized carbon material.

[0010] According to the present invention, preferably, the dosage ratio of sodium chloride, glucose, thiourea and water is (8-9): (0.6-1.0): (1.5-2.5): (50-100) g / g / g / mL.

[0011] According to the present invention, preferably, the mixing and stirring time is 1.5-2.5h.

[0012] According to the present invention, preferably, the freezing time is 12-36 hours, and the freezing temperature is -15°C to -30°C.

[0013] According to the present invention, preferably, the pyrolysis carbonization treatment includes a heating and insulation stage, a cooling stage and a natural cooling stage performed in sequence under the protection of a N2 atmosphere.

[0014] According to the present invention, preferably, the heating rate in the heating and heat preservation stage is 3-8°C / min, the temperature is raised to 850-950°C in the heating and heat preservation stage, and the heat preservation time in the heating and heat preservation stage is 1.5-2.5h.

[0015] According to the present invention, preferably, the cooling rate in the cooling stage is 5-10°C / min, and the temperature is reduced to 450-550°C in the cooling stage.

[0016] In the present invention, as a preferred embodiment, the precursor powder is placed in a tube furnace with a porcelain boat as a carrier, and subjected to pyrolysis and carbonization treatment under the protection of N2 atmosphere.

[0017] In the present invention, as a preferred embodiment, the washing is performed by suction filtration with deionized water for several times to remove sodium chloride.

[0018] According to the present invention, preferably, the vacuum drying temperature is 55-65° C., and the vacuum drying time is 10-15 h.

[0019] The second aspect of the present invention provides a porous sulfide bond functionalized carbon material prepared by the method for preparing the porous sulfide bond functionalized carbon material.

[0020] The third aspect of the present invention provides the use of the porous sulfide bond functionalized carbon material as an active electrode material for a sodium battery.

[0021] According to the present invention, preferably, the porous thioether functionalized carbon material is used as a sulfur cathode material of a sodium battery. Further preferably, the sodium battery is a room temperature (RT) Na-S battery.

[0022] The porous thioether functionalized carbon material prepared by the present invention, which uses glucose and thiourea as carbon source and sulfur source respectively, produces a remarkable reversible capacity when used in sodium storage, because the thioether bond is broken in the voltage range of 0.01-0.50V during the activation process of the room temperature (RT) Na-S battery. During the discharge cycle, the released sulfur reacts with sodium ions to generate insoluble Na2S and Na2S2. In addition, short sulfides and small sulfur species are trapped in the carbon defects caused by the original sulfur doping, which suppresses the fatal problem of the shuttle effect and further significantly improves the performance of the (RT) Na-S battery. Therefore, the use of this thioether functionalized carbon as a cathode has great potential in safe, low-cost, high-energy and long-life (RT) Na-S batteries.

[0023] The beneficial effects of the technical solution of the present invention are as follows:

[0024] (1) The present invention adopts freeze-drying and calcination methods to covalently bond sulfur atoms to the carbon main material, designs and synthesizes a sulfide bond functionalized carbon material (SC). The synthesis method is simple, the conditions are mild, the raw materials are cheap, it can be synthesized on a large scale, it is safe and non-toxic, the reaction cycle is short, the repeatability is high, and the sodium chloride is recyclable.

[0025] (2) The porous sulfide functionalized carbon material prepared by the present invention can be assembled into a sodium battery as an active electrode material. The test results show that the porous sulfide functionalized carbon material prepared by the present invention has excellent reversible capacity, cycle stability and cycle reversibility. Its discharge / charge voltage platform remains overlapped between 0.90-1.50V and 1.60-2.00V in 100 consecutive cycles. It has a charge capacity of 500mA·h·g in 100 cycles. −1 Excellent reversible capacity, and at 100mA·g −1 The high original Coulombic efficiency of 60% for sodium storage at a current density of 2.5 Å was achieved. Moreover, the Coulombic efficiency rose rapidly and reached a stable level of almost 100%.

[0026] (3) The porous sulfide bond functionalized carbon material prepared by the present invention can be used for the preparation and application of sulfur cathode for large-scale energy storage. The porous sulfide bond functionalized carbon material prepared by the present invention is conducive to the promotion and application in the production of advanced (RT) Na-S batteries, and can greatly improve the performance of (RT) Na-S batteries.

[0027] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0029] Figure 1 The SEM image of the porous sulfide bond functionalized carbon material prepared in Example 1 of the present invention is shown.

[0030] Figure 2 The XPS graph of the porous sulfide bond functionalized carbon material prepared in Example 1 of the present invention is shown (wherein, “Intensity” is intensity; “Binding energy” is binding energy; “S 2p” is sulfur 2p electron).

[0031] Figure 3 The Raman spectrum of the porous sulfide bond functionalized carbon material prepared in Example 1 of the present invention is shown (wherein, "Intensity" is intensity; "Raman shift" is Raman shift; "D" is defect, G is graphite; "C" is carbon; and "CS" is sulfur-carbon bond).

[0032] Figure 4 The charge and discharge performance diagram (“Potential (V vs. Na / Na + )” is voltage; “Capacity (mAh g -1 )” is the capacity).

[0033] Figure 5 The Coulombic efficiency diagram of a CR2016 button battery assembled using the porous sulfide bond functionalized carbon material prepared in Example 1 of the present invention is shown (“Cycle number” is the number of cycles; “Coulombic efficiency” is the Coulombic efficiency; “Charge” is charging; and “Discharge” is discharging).

[0034] Figure 6 The graph shows the effect of current density change on the CR2016 button cell assembled with the porous sulfide functionalized carbon material prepared in Example 1 of the present invention (0.1A g -1 , 0.2A g -1 , 0.4A g -1 , 0.8A g -1 , 1.6A g -1 , 3.2A g -1 , “unit” as the unit).

[0035] Figure 7 The long-term cycle performance diagram of a CR2016 button battery assembled using the porous sulfide bond functionalized carbon material prepared in Example 1 of the present invention is shown. DETAILED DESCRIPTION

[0036] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art. Example

[0037] This embodiment provides a method for preparing a porous sulfide bond functionalized carbon material, the preparation method comprising the following steps:

[0038] S1: Dissolve 8.5 g of sodium chloride, 0.8 g of glucose, and 1.9 g of thiourea in 60 mL of deionized water and stir for 2 hours to obtain solution A;

[0039] S2: freeze-drying solution A in a freezing device at -15°C for 24 hours, then placing the freeze-dried solution A ice cubes in a freeze dryer, drying under vacuum conditions, taking them out, and grinding them thoroughly to obtain a precursor powder;

[0040] S3: 200 mg of the precursor powder was placed in a tube furnace with a porcelain boat as a carrier. Under the protection of flowing nitrogen, the pyrolysis and carbonization process was carried out at 900 °C for 2 hours with a heating rate of 5 °C / min, and then the temperature was reduced to 500 °C at a cooling rate of 8 °C / min. After naturally cooling to room temperature, the calcined sample was taken out;

[0041] The calcined sample was filtered and washed with deionized water for several times to remove sodium chloride, and then placed in a vacuum drying oven at 60° C. to dry for 12 hours. After cooling to room temperature, it was taken out and ground to obtain the porous sulfide bond functionalized carbon material.

[0042] like Figure 1-3 Shown are the SEM image, XPS image and Raman spectrum of the porous sulfide bond functionalized carbon material prepared in this example.

[0043] This example uses a CR2016 button cell to test and evaluate the sodium storage performance of the porous sulfide bond functionalized carbon material prepared in this example:

[0044] The cell was assembled in a glove box (mBraun, Germany) filled with high-purity argon (total concentration of O2 and H2O < 0.5 ppm). The cell consisted of a working electrode, a metallic sodium foil counter electrode, and an electrolyte separated by a porous polyethylene membrane (Celgard 2500), where:

[0045] The working electrode was prepared as follows:

[0046] The porous sulfide bond functionalized carbon material prepared in this example: additive (Super P): carboxymethyl cellulose (CMC, Sigma-Aldrich) = 7:1.5:1.5 mass ratio and an appropriate amount of water were mixed to prepare a working electrode slurry. After the working electrode slurry was mixed evenly, the working electrode slurry was loaded onto the copper foil. The loading amount of the working electrode slurry was controlled at 0.9-1.1 mg cm −2 , and then dried in a vacuum oven at 80 °C overnight;

[0047] The material composition of electrolytes includes:

[0048] 1.0mol·L −1 Sodium perchlorate (NaClO4, Alfa Aesar, ≥99%), propylene carbonate (PC, C4H6O3, Sigma-Aldrich, 99.7%), additive (5 vol% fluoroethylene carbonate (C3H3FO3, Alfa Aesar, ≥98%)).

[0049] The test temperature was 25°C, and the power supply was analyzed by Solartron Analytical (Ametek) at a rate of 0.1 mV·s at different voltage ranges. -1 The scanning rate of Na + / Na was subjected to cyclic voltammetry, and the results are as follows:

[0050] like Figure 4 As shown, after the sodiumation / desodiumation process (activation / deactivation) in the first 10 cycles, the discharge / charge voltage platforms overlapped and maintained between 0.90-1.50 V and 1.60-2.00 V, respectively, for 100 consecutive cycles. The repeatability of the discharge and charge curves indicates the excellent cycle reversibility of the porous sulfide bond functionalized carbon material prepared by the present invention.

[0051] like Figure 5 As shown in Figure 2, the porous sulfide bond functionalized carbon material prepared by the present invention has excellent cycle stability, with a charge transfer rate of 500 mA·h·g in 100 cycles. −1 Excellent reversible capacity, and at 100mA·g −1It has a high original Coulombic efficiency of 60% at a current density of 2.5 for sodium storage; in addition, the Coulombic efficiency of the porous sulfide bond functionalized carbon material prepared by the present invention rises rapidly and reaches a stable level of almost 100%.

[0052] Figure 6 The effect of current density on the performance of the CR2016 button cell assembled above is shown. Even if the current density is continuously increased, when the current density is restored to 100 mA·g −1 When the initial value is reached, the capacity shows only a slight decay, and even recovers to the previous capacity, indicating the considerable reversible capacity of the porous sulfide bond functionalized carbon material prepared by the present invention.

[0053] like Figure 7 As shown in Figure 2, even after 800 cycles, the capacity of the CR2016 button cell assembled above is still maintained at 330 mA·h·g −1 , indicating that the porous sulfide bond functionalized carbon material prepared by the present invention exhibits excellent cycle stability, which is better than most reported (RT) Na-S batteries.

[0054] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. Application of porous sulfide bond functionalized carbon material as sulfur cathode material for sodium battery, characterized in that: The sodium battery is a room temperature (RT) Na-S battery; The preparation method of porous sulfide bond functionalized carbon material comprises the following steps: S1: Mix sodium chloride, glucose, thiourea and water and stir to obtain solution A; S2: freezing, vacuum freeze-drying and grinding the solution A in sequence to obtain a precursor powder; S3: sequentially subjecting the precursor powder to pyrolysis carbonization treatment, washing, vacuum drying and grinding to obtain the porous sulfide bond functionalized carbon material; The pyrolysis carbonization treatment includes a heating and heat preservation stage, a cooling stage and a natural cooling stage carried out in sequence under the protection of N2 atmosphere; The heating rate of the heating and heat preservation stage is 3-8°C / min, the temperature is raised to 850-950°C in the heating and heat preservation stage, and the heat preservation time in the heating and heat preservation stage is 1.5-2.5h; The cooling rate in the cooling stage is 5-10°C / min, and the temperature is reduced to 450-550°C in the cooling stage.

2. The use according to claim 1, wherein: The dosage ratio of the sodium chloride, glucose, thiourea and water is (8-9): (0.6-1.0): (1.5-2.5): (50-100) g / g / g / mL.

3. The use according to claim 1, wherein: The mixing and stirring time is 1.5-2.5h.

4. The use according to claim 1, wherein: The freezing time is 12-36 hours, and the freezing temperature is -15°C to -30°C.

5. The use according to claim 1, wherein: The vacuum drying temperature is 55-65° C., and the vacuum drying time is 10-15 hours.

Images