CN110040716B - A kind of preparation method of ultrathin carbon nanosheet negative electrode material for sodium ion battery - Google Patents

Abstract

A preparation method of an ultrathin carbon nanosheet anode material for a sodium ion battery comprises the following steps: 1) respectively dissolving glucose and potassium hydroxide in an ethanol-water mixed solvent, fully stirring and uniformly mixing; 2) pretreating the precursor in an oven at 80-200 ℃ to obtain a precursor 3), and then carrying out one-step pyrolysis and carbonization on the precursor in a tubular atmosphere furnace at the carbonization temperature of 600 ℃ and 900 ℃ to obtain a carbonized product; 4) and (4) carrying out suction filtration and washing on the carbonized product to be neutral, and drying and grinding to obtain the ultrathin carbon nanosheet sodium ion battery cathode material. The method is simple to operate, and the prepared product is uniform in morphology distribution and small in lamella thickness (20-50 nm). The three-dimensional communicated structure and the larger specific surface area provide favorable conditions for the rapid transmission of sodium ions, can obviously improve the electrochemical performance of the material, and has the advantages of low cost and large-scale production.

Description

A kind of preparation method of ultrathin carbon nanosheet negative electrode material for sodium ion battery

technical field

The invention belongs to the technical field of preparation of negative electrode materials for sodium ion batteries, and particularly relates to a method for preparing an ultrathin carbon nanosheet negative electrode material for sodium ion batteries.

technical background

With the extensive use of fossil fuels and the emergence of global environmental problems, it is imperative to replace traditional energy with renewable energy as the main energy source. To effectively utilize these uninterrupted renewable energy sources and a wide range of electric or hybrid electric vehicles, advanced energy storage systems should be developed. Due to their high energy density and low self-discharge rate, lithium-ion batteries (LIBs) have been widely used in millions of portable electronic devices and electric vehicles since 1991 (Dunn B, Tarascon J M. Electrical energy storage for the grid: a battery of choices. [J]. Science, 2011, 334(6058):928-35.). Li-ion battery technology has attracted the attention of researchers worldwide. However, the cost of LIBs has risen due to the limited lithium content (0.0065%) and the uneven distribution of lithium resources on the earth. Sodium is abundant and has similar chemical properties to lithium. Therefore, sodium-ion batteries (SIBs) are considered ideal candidates for cost-effective energy storage.

However, for practical systems and further development studies, it is found that the cycling stability, rate capability and capacity of SIBs still need to be enhanced. Namely, high-performance and low-cost electrode materials, especially suitable anode materials, are in urgent need of development. Carbon materials are considered to be the most promising anode materials for SIBs in practical applications. Various carbon materials have been studied, including graphite, expanded graphite, amorphous carbon, and graphene. Among all carbon anode candidates, hard carbon has attracted much attention due to its high electrochemical activity and relatively low cost. Hard carbon contains a large number of disordered structures with defects and voids, which contribute to the high reversible capacity. However, different morphologies have a greater impact on the initial irreversible capacity loss. Wenzel et al. (Wenzel S, Hara T, Janek J, et al. Room-temperature sodium-ion batteries: Improving the ratecapability of carbon anode materials by templating strategies [J]. Energy & Environmental Science, 2011, 4(9):3342- 3345.) It has been demonstrated that high loadings of carbon anode materials can be obtained by introducing a hierarchical porous structure. Hollow Carbon Nanospheres with Superior Rate Capability for Sodium-BasedBatteries [J]. Advanced Energy Materials, 2012, 2(7): 873-877. ), carbon nanofibers (Chen T, Liu Y, Pan L, et al.Electrospun carbon nanofibers as anode materials for sodiumion batteries with excellent cycle performance[J].Journal of MaterialsChemistry A,2014,2(12):4117-4121 .), bulk carbon (Zhou X, Guo Y G.Highly DisorderedCarbon as a Superior Anode Material for Room-Temperature Sodium-Ion Batteries[J].Chemelectrochem,2014,1(1):83–86.) and bamboo like carbon materials (Li D, Zhang L, Chen H, et al. Nitrogen-doped bamboo-like carbon nanotubes:promising anode materials for sodium-ion batteries[J].Chemical Communications,2015,51(89):16045-16048.) and Porous Carbon (Chen Li, Li Xiaopeng, Chen Yuchi, et al. Research on Waste Biomass Water Hyacinth Porous Carbon for Lithium-ion and Na-ion Batteries [J]. Chemical Research and Applications, 2017,29(10):1525-1529 .) and other carbon materials with different morphologies. The carbon materials with different morphologies showed excellent electrochemical performance when they were used as anodes for Na-ion batteries.

In conclusion, designing hierarchical porous structures is an effective strategy to improve the storage capacity of carbon-based materials by optimizing the transport path of Na ⁺ . Therefore, the rate performance of carbonaceous anode materials for SIBs can also be improved by designing hybrid nanostructures containing porous nanosheets.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide an easy-to-implement, low-cost and high-conductivity method for preparing an ultra-thin carbon nanosheet negative electrode material for sodium ion batteries, and the prepared ultra-thin carbon nanosheet negative electrode material can effectively improve the ionic and electronic properties Diffusion transport improves battery performance.

To achieve the above object, the present invention adopts the following technical solutions:

1) get 1g of glucose and 0.3～1g of potassium hydroxide and dissolve in two parts of 10～50ml ethanol-water mixed solvent respectively, stir to make glucose solution and potassium hydroxide solution respectively;

2) Mix and stir the glucose solution and the potassium hydroxide solution to obtain the precursor B;

3) Put the precursor B into an oven, and pretreat it at 80-200°C to obtain a tan product C;

4) Transfer the product C into the crucible, then put it into a vacuum tube furnace, and under the protection of argon, the temperature is raised from room temperature to 600-900°C at a heating rate of 2-10°C/min for 1-3 hours, and then heated with argon. The temperature was lowered to 300°C at a cooling rate of 10°C/min, and then cooled to room temperature naturally to obtain hard carbon nanosheets;

5) The hard carbon nanosheets are respectively washed with deionized water and absolute ethanol by suction filtration until neutral, and after drying, an ultrathin carbon nanosheet negative electrode material for sodium ion batteries is obtained.

The glucose and potassium hydroxide in the step 1) are ground for 30-60min respectively.

The ethanol-water mixed solvent in the step 1) is formed by mixing water: anhydrous ethanol in a volume ratio of 1-9:1.

The stirring in the step 2) adopts magnetic stirring for 0.5-2.0 h.

In the step 3), the preprocessing time is 60-180 min.

The crucible in the step 4) is an aluminum oxide crucible.

In the step 4), the flow rate of argon gas is 0.1-1.0 sccm/min.

In the step 5), the drying temperature is 80-120° C., and the time is 8-12 h.

In the step 5), the thickness of the ultrathin carbon nanosheet negative electrode material for sodium ion battery is 20-50 nm.

The beneficial effects of the present invention are embodied in:

1) The present invention adopts a simple one-step solid-phase preparation process, without adding other template agents and surfactants, and the pyrolysis and carbonization reactions are completed in a vacuum tube furnace at one time, without other post-processing, reducing production costs;

2) The thickness of the ultrathin hard carbon nanosheets prepared by this method is between 20 and 50 nm. A three-dimensional interconnected network structure is formed between carbon nanosheets, and the three-dimensional porosity makes it have a large specific surface area, which can be fully contacted with the electrode material, providing more attachment sites for sodium ions, thereby improving the electrode reaction efficiency and making it more efficient. high capacity. The existence of the three-dimensional porous structure is beneficial to the diffusion of the electrolyte and the migration of sodium ions, and promotes the de-intercalation of sodium ions, so that it has good rate performance. The three-dimensional porous structure can reduce the ohmic internal resistance of the electrode material. Therefore, the carbon materials prepared under this condition have good electrochemical performance.

3) The raw materials used in the present invention are glucose and potassium hydroxide with stable chemical components, and the technical process of the method is simple, the technical process of the method is simple, the reaction temperature is low, the time is short, no subsequent treatment is required, and it is environmentally friendly and easy to use. Factory production.

Description of drawings

Fig. 1 is the XRD pattern of the ultrathin carbon nanosheet negative electrode material for sodium ion battery prepared in Example 1 of the present invention;

2 is a SEM image of the ultrathin carbon nanosheet negative electrode material for sodium ion batteries prepared in Example 2 of the present invention;

3 is a SEM image of the ultra-thin carbon nanosheet negative electrode material for sodium ion batteries prepared in Example 3 of the present invention;

4 is a Raman diagram of the ultrathin carbon nanosheet negative electrode material for sodium ion batteries prepared in Example 1 of the present invention;

5 is a TEM image of the ultrathin carbon nanosheet negative electrode material for sodium ion batteries prepared in Example 1 of the present invention.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments, but the present invention is not limited to the following embodiments.

Example 1:

1) Mix water: anhydrous ethanol in a volume ratio of 1:1 to obtain an ethanol-water mixed solvent, then take 1 g of glucose and 0.3 g of potassium hydroxide and grind them for 30 minutes and dissolve in two 10 ml of ethanol-water mixed solvent respectively. , stir to make glucose solution and potassium hydroxide solution;

2) Mix the glucose solution and the potassium hydroxide solution with magnetic stirring for 0.5h to obtain the precursor B;

3) Put the precursor B into an oven, and pre-treat it at 80° C. for 180 min to obtain a tan product C;

4) Transfer the product C into an aluminum oxide crucible, then put it into a vacuum tube furnace, and heat it up from room temperature to 600 °C at a heating rate of 2 °C/min under an argon flow rate of 0.1 sccm/min for 3 h. , and then the temperature was lowered to 300°C at a cooling rate of 10°C/min, and then cooled to room temperature naturally to obtain hard carbon nanosheets;

5) The hard carbon nanosheets are respectively washed with deionized water and absolute ethanol by suction filtration until neutral, and dried at 80° C. for 12 hours to obtain an ultrathin carbon nanosheet negative electrode material for sodium ion batteries with a sheet thickness of 20-50 nm.

It can be seen from Fig. 1 that the X-ray diffraction (XRD) patterns of the prepared ultrathin carbon nanosheet anode materials show two weak broad diffraction peaks (002) and (100) at 23° and 44°, respectively, indicating that their Amorphous nature.

It can be seen from Figure 4 that there are two independent characteristic peaks of D band and G band in the Raman spectrum of the prepared ultrathin carbon nanosheet anode material, which are located at ~1346 cm-1 and ~1591 cm-1, respectively. The D peak corresponds to sp3 hybrid carbon with disordered state and the G peak corresponds to sp2 hybrid carbon with graphitic structure. The integrated intensity ratio (IG/ID) of the G peak to the D peak can be used to evaluate the degree of graphitization. A higher IG/ID value indicates more graphitic structure, and a higher degree of graphitization indicates a higher electrical conductivity. The Raman fitting results indicate that the as-prepared samples have a high degree of graphitization, which is beneficial to the charge transfer during the electrochemical reaction.

It can be seen from Figure 5 that the transmission electron microscope (TEM) image of the prepared ultra-thin carbon nanosheet negative electrode material proves that the prepared carbon nanosheet has a smaller sheet thickness, which is conducive to the transmission of electrons and reduces the concentration of Na+. diffusion pathway.

Example 2:

1) Mix water: absolute ethanol in a volume ratio of 3:1 to obtain an ethanol-water mixed solvent, then take 1 g of glucose and 0.5 g of potassium hydroxide and grind them for 50 min and dissolve in two 20 ml of ethanol-water mixed solvent respectively. , stir to make glucose solution and potassium hydroxide solution;

2) Mix the glucose solution and the potassium hydroxide solution with magnetic stirring for 1 h to obtain the precursor B;

3) Put the precursor B into an oven, and pre-treat it at 120° C. for 120 min to obtain a tan product C;

4) Transfer the product C into an alumina crucible, then put it into a vacuum tube furnace, and heat it up from room temperature to 700°C for 2h at a heating rate of 5°C/min under an argon flow rate of 0.3sccm/min. , and then the temperature was lowered to 300°C at a cooling rate of 10°C/min, and then cooled to room temperature naturally to obtain hard carbon nanosheets;

5) The hard carbon nanosheets are respectively washed with deionized water and absolute ethanol by suction filtration until neutral, and dried at 100° C. for 10 h to obtain the ultrathin carbon nanosheet negative electrode material for sodium ion batteries with a sheet thickness of 20-50 nm.

It can be seen from Figure 2 that the SEM image of the prepared ultra-thin carbon nanosheet negative electrode material shows that the thickness of the interconnected carbon nanosheets is 20-50 nm. diffusion pathway.

Example 3:

1) Mix water: absolute ethanol in a volume ratio of 5:1 to obtain an ethanol-water mixed solvent, then take 1g of glucose and 0.7g of potassium hydroxide and grind them for 60min respectively and dissolve in two 25ml of ethanol-water mixed solvent. , stir to make glucose solution and potassium hydroxide solution;

2) Mix the glucose solution and the potassium hydroxide solution with magnetic stirring for 1.5h to obtain the precursor B;

3) Put the precursor B into an oven, and pre-treat it at 160° C. for 120 min to obtain a tan product C;

4) Transfer the product C into an aluminum oxide crucible, then put it into a vacuum tube furnace, and heat it up from room temperature to 800 °C at a heating rate of 7 °C/min under an argon flow rate of 0.5 sccm/min for 1 h. , and then the temperature was lowered to 300°C at a cooling rate of 10°C/min, and then cooled to room temperature naturally to obtain hard carbon nanosheets;

5) The hard carbon nanosheets are respectively washed with deionized water and absolute ethanol by suction filtration until neutral, and dried at 120° C. for 8 hours to obtain an ultrathin carbon nanosheet negative electrode material for sodium ion batteries with a sheet thickness of 20-50 nm.

It can be seen from Figure 3 that the SEM image of the prepared ultra-thin carbon nanosheet anode material shows that the carbon nanosheets are three-dimensionally interconnected to form multi-level pores, which increases their specific surface area and is conducive to the diffusion and transport of electrolyte.

Example 4:

1) Mix water: absolute ethanol in a volume ratio of 9:1 to obtain an ethanol-water mixed solvent, then take 1 g of glucose and 1 g of potassium hydroxide and grind them for 40 minutes and dissolve in two 30 ml of ethanol-water mixed solvent respectively. , stir to make glucose solution and potassium hydroxide solution;

2) Mix the glucose solution and the potassium hydroxide solution with magnetic stirring for 2h to obtain the precursor B;

3) Put the precursor B into an oven, and pre-treat it at 200° C. for 60 min to obtain a tan product C;

4) Transfer the product C into an alumina crucible, then put it into a vacuum tube furnace, and heat it up from room temperature to 900 °C for 1 h at a heating rate of 10 °C/min under an argon flow rate of 0.8 sccm/min. , and then the temperature was lowered to 300°C at a cooling rate of 10°C/min, and then cooled to room temperature naturally to obtain hard carbon nanosheets;

5) The hard carbon nanosheets are respectively washed with deionized water and absolute ethanol by suction filtration until neutral, and dried at 90° C. for 11 h to obtain an ultrathin carbon nanosheet negative electrode material for sodium ion batteries with a sheet thickness of 20-50 nm.

Example 5:

1) Mix water: absolute ethanol in a volume ratio of 8:1 to obtain an ethanol-water mixed solvent, then take 1 g of glucose and 0.5 g of potassium hydroxide and grind them for 50 min and dissolve in two 40 ml of ethanol-water mixed solvent respectively. , stir to make glucose solution and potassium hydroxide solution;

2) Mix the glucose solution and the potassium hydroxide solution with magnetic stirring for 2h to obtain the precursor B;

3) Put the precursor B into an oven, and pre-treat it at 120° C. for 120 min to obtain a tan product C;

4) Transfer the product C into an aluminum oxide crucible, then put it into a vacuum tube furnace, and heat it up from room temperature to 800°C for 2h at a heating rate of 5°C/min under an argon flow rate of 1sccm/min, Then, the temperature was lowered to 300°C at a cooling rate of 10°C/min, and then cooled to room temperature naturally to obtain hard carbon nanosheets;

5) The hard carbon nanosheets are respectively washed with deionized water and absolute ethanol by suction filtration until neutral, and dried at 110° C. for 9 hours to obtain an ultrathin carbon nanosheet negative electrode material for sodium ion batteries with a sheet thickness of 20-50 nm.

Example 6:

1) Mix water: absolute ethanol in a volume ratio of 6:1 to obtain an ethanol-water mixed solvent, then take 1 g of glucose and 0.7 g of potassium hydroxide and grind them for 40 minutes and dissolve in two 50 ml of ethanol-water mixed solvent respectively. , stir to make glucose solution and potassium hydroxide solution;

2) Mix the glucose solution and the potassium hydroxide solution with magnetic stirring for 1 h to obtain the precursor B;

3) Put the precursor B into an oven, and pre-treat it at 160° C. for 60 min to obtain a tan product C;

4) Transfer the product C into an alumina crucible, then put it into a vacuum tube furnace, and heat it up from room temperature to 700°C for 2.5h at a heating rate of 2°C/min under an argon flow rate of 1sccm/min. , and then the temperature was lowered to 300°C at a cooling rate of 10°C/min, and then cooled to room temperature naturally to obtain hard carbon nanosheets;

5) The hard carbon nanosheets are respectively washed with deionized water and absolute ethanol by suction filtration until neutral, and dried at 100° C. for 10 h to obtain the ultrathin carbon nanosheet negative electrode material for sodium ion batteries with a sheet thickness of 20-50 nm.

Claims (9)

1. a preparation method of ultrathin carbon nanosheet negative electrode material for sodium ion battery, is characterized in that, comprises the following steps: 1) get 1g of glucose and 0.3～1g of potassium hydroxide and dissolve in two parts of 10～50ml ethanol-water mixed solvent respectively, stir to make glucose solution and potassium hydroxide solution respectively; 2) Mix and stir the glucose solution and the potassium hydroxide solution to obtain the precursor B; 3) Put the precursor B into an oven, and pretreat it at 80-200°C to obtain a tan product C; 4) Transfer the product C into the crucible, then put it into a vacuum tube furnace, and under the protection of argon, the temperature is raised from room temperature to 600-900°C at a heating rate of 2-10°C/min for 1-3 hours, and then heated with argon. The temperature was lowered to 300°C at a cooling rate of 10°C/min, and then cooled to room temperature naturally to obtain hard carbon nanosheets; 5) The hard carbon nanosheets are respectively washed with deionized water and absolute ethanol by suction filtration until neutral, and after drying, an ultrathin carbon nanosheet negative electrode material for sodium ion batteries is obtained. 2. The preparation method of ultra-thin carbon nanosheet negative electrode material for sodium ion battery according to claim 1, wherein the glucose and potassium hydroxide in the step 1) are ground for 30-60min respectively. 3. the preparation method of the ultrathin carbon nanosheet negative electrode material for sodium ion battery according to claim 1, is characterized in that, the ethanol-water mixed solvent of described step 1) is water: dehydrated alcohol is 1～9: 1 volume ratio. 4 . The method for preparing an ultrathin carbon nanosheet negative electrode material for sodium ion batteries according to claim 1 , wherein the stirring in step 2) adopts magnetic stirring for 0.5-2.0 h. 5 . 5 . The method for preparing an ultra-thin carbon nanosheet negative electrode material for a sodium-ion battery according to claim 1 , wherein the pretreatment time of the step 3) is 60-180 min. 6 . 6 . The method for preparing an ultra-thin carbon nanosheet negative electrode material for sodium ion batteries according to claim 1 , wherein the crucible in the step 4) is an aluminum oxide crucible. 7 . 7 . The method for preparing an ultra-thin carbon nanosheet negative electrode material for sodium ion batteries according to claim 1 , wherein in the step 4) the flow rate of argon gas is 0.1-1.0 sccm/min. 8 . 8 . The method for preparing an ultra-thin carbon nanosheet negative electrode material for a sodium ion battery according to claim 1 , wherein the drying temperature in step 5) is 80-120° C. and the time is 8-12 h. 9 . 9. The preparation method of the ultrathin carbon nanosheet negative electrode material for sodium ion battery according to claim 1, wherein the step 5) the thickness of the ultrathin carbon nanosheet negative electrode material for sodium ion battery is 20～20 50nm.

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