CN103915630A - Molybdenum disulfide/mesoporous carbon composite electrode material as well as preparation method and application thereof - Google Patents

Abstract

The invention discloses a molybdenum disulfide/mesoporous carbon composite electrode material and its preparation method and application, using oleic acid and sodium oleate as structure-directing agents, using sodium molybdate and thiourea as molybdenum and sulfur sources, water Molybdenum disulfide precursors intercalated into oleic acid molecules were prepared by thermal reaction; then dopamine was introduced into the interlayer by the chemical reaction between dopamine and oleic acid molecules; finally, the three-block copolymer polyoxyethylene-polyoxypropylene-polyoxyethylene As a soft template, the self-polymerization of dopamine between molybdenum disulfide layers into polydopamine and the subsequent high-temperature carbonization process were used to prepare nano-hybrid materials with mesoporous carbon intercalated between molybdenum disulfide layers. The intercalation of mesoporous carbon not only expands the interlayer spacing of MoS2, effectively prevents the redeposition of nanosheets, but also significantly improves the electronic conductivity of MoS2. The results of electrochemical tests show that it has high specific capacity, excellent rate and cycle performance as the anode material of lithium-ion batteries, and can be widely used in the field of lithium-ion batteries.

Description

A kind of molybdenum disulfide/mesoporous carbon composite electrode material and its preparation method and application

technical field

The invention relates to the field of new energy materials, and relates to a lithium-ion battery electrode material and its preparation method and application, in particular to a nano-hybrid material in which mesoporous carbon is embedded between molybdenum disulfide layers.

Background technique

Lithium-ion batteries occupy an increasingly important position in portable electronic devices, electric vehicles and other fields because of their advantages such as large energy density and long cycle life. However, with the development of science and technology, people have put forward higher requirements on the performance of lithium-ion batteries for energy storage devices. Electrode materials are one of the key issues that need to be solved for lithium-ion batteries. Carbon materials are currently the preferred anode materials for commercial lithium-ion batteries due to their lower cost and longer cycle life. However, the low initial charge-discharge efficiency, low specific capacity, and organic solvent co-intercalation of carbon materials have prompted people to continue research and look for alternatives to carbon anode materials.

In recent years, two-dimensional layered molybdenum disulfide materials have attracted increasing attention as new anode materials for lithium-ion batteries, because molybdenum disulfide materials have the advantages of high energy density, low cost, no pollution, etc. Stability performance, but its intercalation/delithiation potential is lower than that of metal oxides, the electrochemical reaction rate is slow under low temperature conditions, and the rate charge and discharge performance of the material is not ideal, which is one of the main bottlenecks restricting its development. At present, the improvement methods for molybdenum disulfide materials mainly include structural optimization and carbon material compounding. For example, Du et al. (Du, G; Guo, Z; Wang, S.; Zeng, R.; Chen, Z.; Liu, H., Chem. Commun. 2010, 46:1106) by The re-stacking of molybdenum disulfide nanosheets can obtain a larger layer spacing, and at a charge-discharge density of 50mA/g, the discharge capacity of 750mAh/g is still maintained after 20 cycles. The low electronic conductivity of molybdenum disulfide also limits the improvement of its electrochemical performance. Chen et al. (Chang K.; Chen, W.X., ACS Nano, 2011,5:4720) used L-cysteine as an auxiliary agent to prepare molybdenum disulfide/graphene composites with high capacity and good Excellent cycle performance, with a charge and discharge current of 100mA/g, the capacity exceeds 1100mAh/g after 100 cycles.

Contents of the invention

The object of the present invention is to provide a mesoporous carbon embedded molybdenum disulfide interlayer nano-hybrid material and its preparation method and application, so as to overcome the above-mentioned defects in the existing electrode materials. The design idea is as follows:

The ultra-thin molybdenum disulfide nanosheets intercalated with oleic acid molecules were prepared by hydrothermal method, and then dopamine was introduced into the interlayer through the chemical reaction between oleic acid molecules and dopamine. A polydopamine layer is formed between them, and then carbonized at a high temperature to form a nano-hybrid material in which mesoporous carbon is embedded between molybdenum disulfide layers. In the prepared hybrid material, the embedding of the carbon layer not only expands the interlayer spacing of molybdenum disulfide, improves the utilization rate of the electrochemical activity of the material, but also helps to improve its electrical conductivity and ensure its high power performance.

The present invention is achieved through the following technical solutions:

A molybdenum disulfide/mesoporous carbon composite electrode material, the structure of the composite electrode material is: a monoatomic carbon layer is evenly embedded between molybdenum disulfide nanosheets; wherein, the molybdenum disulfide nanosheets The diameter is 200-300nm, the thickness is 10-20nm, and the interlayer distance between adjacent molybdenum disulfide nanosheets is 0.76-1.04nm.

A preparation method of molybdenum disulfide/mesoporous carbon composite electrode material, comprising the steps of:

(1) Dissolve 1.5～3.0g sodium oleate, 1.0～2.0g sodium molybdate, 0.93～1.86g thiourea in a mixed solvent of 15～30ml deionized water, 15～30ml ethanol and 2～40ml oleic acid, Use nitric acid to adjust the pH value to less than 1. After stirring evenly, conduct a hydrothermal reaction at 140-180°C for 24-36 hours. After cooling to room temperature, wash and collect the reaction product;

(2) Dissolve 0.2～0.6g triblock copolymer polyoxyethylene-polyoxypropylene-polyoxyethylene in 200～600ml water, then add 0.25～0.75g trometamol and stir evenly to obtain a buffer solution, and then The product obtained in (1) is dispersed in the buffer solution, cooled to room temperature after ultrasonication for 30-90 min;

(3) Add 250-500 mg of dopamine while stirring to the final product of step (2), stir and react at 10-40°C for 3-24 hours, filter and centrifuge to wash and collect the reaction product;

(4) Carbonizing the product obtained in step (3) at 600-900° C. for 2-4 hours in an inert atmosphere to obtain the molybdenum disulfide/mesoporous carbon composite electrode material.

The structure of the composite electrode material is: a monoatomic carbon layer is evenly embedded between molybdenum disulfide nanosheets; wherein, the diameter of the molybdenum disulfide nanosheets is 200-300nm, and the thickness is 10-20nm. The interlayer spacing of adjacent molybdenum disulfide nanosheet layers is 0.76-1.04 nm.

The weight ratio of sodium molybdate to dopamine is 2:1˜4:1.

The inert atmosphere is argon.

The application of the molybdenum disulfide/mesoporous carbon composite electrode material, that is, the composite electrode material is used as a negative electrode material in lithium ion batteries.

It can be seen from the above technical scheme and implementation method that the molybdenum disulfide/mesoporous carbon composite electrode material (nano-hybrid material in which mesoporous carbon is embedded between molybdenum disulfide layers) prepared by the present invention can show excellent performance when used as a lithium ion battery negative electrode material. electrochemical performance. The embedding of the carbon layer not only expands the interlayer spacing of molybdenum disulfide (for example, from the original 0.64nm to 0.98nm), improves the electrochemical activity utilization of the material, but also helps to improve its conductivity and ensure its high power performance , It has excellent rate performance and cycle stability when applied in the field of lithium-ion battery anode materials.

Description of drawings

Fig. 1 is the XRD curve of embodiment 1 product;

Fig. 2 is the transmission electron micrograph of embodiment 1 product;

Fig. 3 is the electrochemical test result of the product prepared in Example 1 used as the negative electrode material of lithium ion battery.

Detailed ways

The specific implementation manner of the present invention will be further described in detail below in conjunction with the accompanying drawings and examples, but the protection scope of the present invention should not be limited thereby.

Example 1

Dissolve 1.5g sodium oleate, 1.0g sodium molybdate, and 0.9g thiourea in a mixed solvent of 15ml deionized water, 15ml ethanol and 2ml oleic acid, adjust the pH value to less than 1 with nitric acid, stir evenly, and The hydrothermal reaction was carried out at ℃ for 24 h, and after cooling to room temperature, the reaction product was washed and collected.

Dissolve 0.2g P123 in 200ml water, then add 0.25g trometamol and stir evenly to obtain a buffer solution, then disperse the above reaction product in 200ml of the buffer solution, sonicate for 30min and cool to room temperature, add 250mg dopamine while stirring , stirred at 10°C for 3 h, and the reaction product was collected by filtration and centrifugation.

The obtained product was subjected to high-temperature carbonization in an argon atmosphere, and reacted at 600°C for 2 hours to obtain a molybdenum disulfide/mesoporous carbon composite electrode material, that is, a nano-hybrid material in which mesoporous carbon is embedded between molybdenum disulfide layers. The XRD curve of the product is shown in Figure 1, and the transmission electron microscope photo of the product is shown in Figure 2. Wherein, the molybdenum disulfide nanosheets have a diameter of 200-300 nm and a thickness of 10-20 nm, and the interlayer distance between adjacent molybdenum disulfide nanosheets is about 0.98 nm.

It was used as the anode material of lithium ion battery, and its electrochemical performance was tested by CR2016 button cell. Figure 3 is a graph of the rate charge and discharge test results of the material. It can be seen from the figure that as the current density increases, its capacity decreases slowly, indicating that this material has better rate charge and discharge performance. Moreover, the capacity remains stable for several cycles at each rate, and the capacity can be recovered well when the current density returns to a low rate, proving that this material has good cycle stability.

Example 2

Dissolve 2g of sodium oleate, 1.5g of sodium molybdate, and 1.4g of thiourea in a mixed solvent of 20ml of deionized water, 20ml of ethanol, and 3ml of oleic acid, adjust the pH value to less than 1 with nitric acid, stir evenly, and heat at 160°C Carry out hydrothermal reaction for 30h, wash and collect the reaction product after cooling to room temperature.

Dissolve 0.3g of P123 in 300ml of water, then add 0.5g of trometamol and stir to obtain a buffer solution, then disperse the product obtained above in 100ml of the buffer solution, sonicate for 60min and cool to room temperature, then add 350mg of dopamine while stirring, The reaction was stirred at 250°C for 16 hours, and the reaction product was collected by filtration and centrifugation.

The obtained product was subjected to high-temperature carbonization in an argon atmosphere, and reacted at 850° C. for 34 hours to obtain a nano-hybrid material in which mesoporous carbon was embedded between molybdenum disulfide layers. The electrochemical test is partly the same as in Example 1, and the prepared material shows almost the same experimental results as in Example 1.

Example 3

Dissolve 3.0g sodium oleate, 2.0g sodium molybdate, and 2.0g thiourea in a mixed solvent of 30ml deionized water, 30g ethanol and 2ml oleic acid, adjust the pH value to less than 1 with nitric acid, stir evenly, and °C for hydrothermal reaction for 36 h, after cooling to room temperature, wash and collect the reaction product.

Dissolve 0.6g of P123 in 600ml of water, then add 0.75g of trometamol and stir to obtain a buffer solution, then disperse the above-mentioned obtained product in 200ml of the buffer solution, ultrasonically cool to room temperature after 90min, and add 500mg of dopamine while stirring, The reaction was stirred at 40°C for 24 hours, and the reaction product was collected by filtration and centrifugation.

The obtained product was subjected to high-temperature carbonization in an argon atmosphere, and reacted at 900° C. for 4 hours to obtain a nano-hybrid material with mesoporous carbon intercalated between molybdenum disulfide layers. The electrochemical test is partly the same as in Example 1, and the prepared material shows almost the same experimental results as in Example 1.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the implementation scope of the present invention. Anyone with ordinary knowledge in the technical field can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be determined by the scope defined in the claims.

Claims (6)

1. A molybdenum disulfide/mesoporous carbon composite electrode material is characterized in that the structure of the composite electrode material is: a monoatomic carbon layer is evenly embedded between molybdenum disulfide nanosheets; wherein the two The molybdenum sulfide nanosheets have a diameter of 200-300nm and a thickness of 10-20nm, and the interlayer distance between adjacent molybdenum disulfide nanosheets is 0.76-1.04nm. 2. a preparation method of molybdenum disulfide/mesoporous carbon composite electrode material, is characterized in that, comprises the steps: (1) Dissolve 1.5～3.0g sodium oleate, 1.0～2.0g sodium molybdate, 0.93～1.86g thiourea in a mixed solvent of 15～30ml deionized water, 15～30ml ethanol and 2～40ml oleic acid, Use nitric acid to adjust the pH value to less than 1, and after stirring evenly, conduct a hydrothermal reaction at 140-180°C for 24-36 hours to obtain a reaction product; (2) Dissolve 0.2～0.6g triblock copolymer polyoxyethylene-polyoxypropylene-polyoxyethylene in 200～600ml water, then add 0.25～0.75g trometamol and stir evenly to obtain a buffer solution, and then The product obtained in (1) is dispersed in the buffer solution, cooled to room temperature after ultrasonication for 30-90 min; (3) Add 250-500 mg of dopamine while stirring to the final product of step (2), stir and react at 10-40°C for 3-24 hours, filter and centrifuge to wash and collect the reaction product; (4) Carbonizing the product obtained in step (3) at 600-900° C. for 2-4 hours in an inert atmosphere to obtain the molybdenum disulfide/mesoporous carbon composite electrode material. 3. The preparation method according to claim 2, wherein the structure of the composite electrode material is: a monoatomic carbon layer is evenly embedded between molybdenum disulfide nanosheets; wherein, the molybdenum disulfide nanosheets The diameter of the sheet is 200-300nm, the thickness is 10-20nm, and the interlayer distance between adjacent molybdenum disulfide nano-sheets is 0.76-1.04nm. 4. The preparation method according to claim 2, characterized in that the weight ratio of sodium molybdate to dopamine is 2:1-4:1. 5. The preparation method according to claim 2, characterized in that, the inert atmosphere is argon. 6. The application of the molybdenum disulfide/mesoporous carbon composite electrode material according to claim 1, characterized in that, the composite electrode material is applied to a lithium-ion battery as a negative electrode material.