CN104037416B - Preparation method of three-dimensional wrinkled graphene self-healing coated nickel sulfide structure electrode - Google Patents

Abstract

The invention relates to a preparation method of a three-dimensional wrinkled graphene self-repairing coated nickel sulfide structure electrode, comprising the following steps: 1) preparing NaOH solution, adding S, Na ₂ S 9H ₂ O to it, and stirring in a water bath; 2) adding graphene Dispersion, magnetic stirring; 3) adding dilute hydrochloric acid, adjusting the pH of the solution, and magnetic stirring; 4) suction filtration to obtain graphene-coated sulfur particles, and drying in the air; 5) using commercial nickel foam, soaking, and setting aside for later use; 6) Put it in the inner lining of the reaction kettle, add deionized water, seal it and react it with water heat, and cool it to room temperature; 7) Rinse it with alcohol and water, then soak it in hydrazine hydrate aqueous solution, and finally dry it in the air . The beneficial effects of the present invention are: based on the shrinkage strain driving mechanism, a three-dimensional wrinkled graphene self-repairing coated nickel sulfide structure electrode is prepared, which can realize fast charging and discharging of large current, and the cycle number can reach 1000 times, and the capacity basically does not decay.

Description

Preparation method of three-dimensional wrinkled graphene self-healing coated nickel sulfide structure electrode

technical field

The invention belongs to the technical field of nanometer materials and electrochemistry, and in particular relates to a preparation method of a three-dimensional wrinkled graphene self-repairing coated nickel sulfide structure electrode, and the material can be used as a negative electrode material of a lithium ion battery.

Background technique

With the increasing energy demand, energy storage devices play an increasingly important role in improving energy utilization efficiency. Recently, as an important component of energy storage devices, lithium-ion batteries are widely used in hybrid vehicles and portable devices due to their high energy density. Research on lithium-ion battery electrode materials with longer cycle life, higher reversible capacity, and lower production cost is one of the frontiers and hotspots of current research. Transition metal oxides, sulfides, and fluorides have been widely concerned and studied by scientists due to their ultra-high theoretical specific capacity (some up to 1000mAh/g). Nickel sulfide is a typical transition metal sulfide material. It is a promising electrode material for lithium-ion batteries, but its development is limited by its low electrical conductivity and excessive changes in electrode structure during charge-discharge cycles.

In recent years, in order to shorten the diffusion distance of lithium ions inside the electrode material and increase the power density of lithium-ion batteries, it has become a trend to use three-dimensional bicontinuous electrodes, and the use of graphene carbon material additives with ultra-high conductivity and large specific surface area can also greatly improve the Improve the electrochemical performance of lithium-ion batteries.

In addition, the three-dimensional wrinkled graphene self-healing coated nickel sulfide structure electrode does not need any additives, and can be directly used as an electrode, which greatly reduces the battery preparation process, meets the requirements of green chemistry, and is conducive to market promotion.

Contents of the invention

The object of the present invention is to provide a preparation method of a three-dimensional wrinkled graphene self-repairing coated nickel sulfide structure electrode, the preparation process is simple, the energy consumption is low, and the obtained three-dimensional wrinkled graphene self-repairing coating nickel sulfide structure electrode has good electrochemical performance.

In order to achieve the above object, the technical solution of the present invention is: a preparation method of a three-dimensional wrinkled graphene self-repairing coated nickel sulfide structure electrode, comprising the following steps:

1) Prepare 50mL of NaOH solution with a mass fraction of 10%, add 0.25gS, 0.65gNa ₂ S·9H ₂ O to it, stir in a water bath until an orange-yellow transparent solution is formed, and the temperature of the water bath is between 60-80 degrees Celsius;

2) Add 15 mL of graphene dispersion to the solution obtained in step 1), and magnetically stir for 1 hour;

3) Add 72 mL of dilute hydrochloric acid with a mass fraction of 5% to the solution obtained in step 2), adjust the pH of the solution to 2, a white precipitate is precipitated, and stir magnetically for 1 hour;

4) Suction filtration of the suspension obtained in step 3) to obtain graphene-coated sulfur particles, and drying in air at 70 degrees Celsius for 24 hours;

5) Use a piece of commercial nickel foam with a diameter of 18mm, soak it in 2mol/L dilute hydrochloric acid for 15 minutes, then soak it in alcohol for 10 minutes, then soak it in deionized water for 10 minutes, and reserve it for later use;

6) 40mg of graphene-coated sulfur particles obtained in step 4), and a piece of nickel foam obtained in step 5), are placed in the inner lining of a polytetrafluoroethylene reactor of 100mL, and 40mL of deionized water is added. Under the centigrade degree of hydrothermal reaction for 4 hours, cool to room temperature after completion of the reaction;

7) Rinse the three-dimensional wrinkled graphene self-repairing coated nickel sulfide structure electrode obtained in step 6) with alcohol and water, then soak it in 0.048% hydrazine hydrate aqueous solution for 3 hours, and finally place it in the air at 70 degrees Celsius Dry for more than 24 hours.

According to the above scheme, the preparation of the described graphene dispersion in step 2) follows the steps:

a) Add 1g of graphite powder and 23ml of concentrated sulfuric acid in a 250ml Erlenmeyer flask, mix and stir at room temperature for 24 hours;

b) Put the Erlenmeyer flask into a constant temperature water bath, the reaction temperature is 40 degrees Celsius, add 100 mg NaNO ₃ to the dispersion obtained in step a), stir for 5 minutes, then slowly add 1500 mg KMnO ₄ , and keep the solution temperature below 45 degrees Celsius, stir 30 minutes;

c) Add 3ml of deionized water to the dispersion obtained in step b), stir for 5 minutes, then add 3ml of deionized water, then stir for 5 minutes, then add 40ml of deionized water, and stir for 15 minutes;

d) Remove the Erlenmeyer flask from the water bath, add 140ml of deionized water and 10ml of 30% H ₂ O ₂ to terminate the oxidation reaction;

e) The suspension obtained in step d) was washed twice with a 5% HCl solution, then washed with deionized water until neutral, dispersed in 100ml of deionized water, and ultrasonicated for 60 minutes;

f) centrifuge the suspension obtained in step e) at 8000 rpm for 5 minutes, and repeatedly take the supernatant until a uniform graphene dispersion is separated with a concentration of 4.7 mg/ml.

The three-dimensional wrinkled graphene self-repairing coated nickel sulfide structure electrode prepared by the present invention can be used as the negative electrode of lithium ion battery. At the same time, the self-adaptive strain relaxation properties have a good protective effect on the huge changes in the structure of the buffer electrode material during charging and discharging. The remaining steps of the lithium-ion battery preparation method are the same as the usual preparation method.

The beneficial effects of the present invention are: through the water bath-hydrothermal two-step method, based on the shrinkage strain driving mechanism, a three-dimensional wrinkled graphene self-repairing coated nickel sulfide structure electrode can be prepared, which can realize fast charging and discharging of large current (at a current density of 20A/g It only takes about 1 minute to complete charging), and the number of cycles can reach 1000 times, and the capacity basically does not decay.

Description of drawings

Fig. 1 is the XRD figure (Ni ₃ S ₂ represents trinickel disulfide) of wrinkled graphene coating nickel sulfide particles on the three-dimensional wrinkled graphene self-repairing coating nickel sulfide structure electrode of the embodiment of the present invention;

Fig. 2 is the SEM figure of the three-dimensional wrinkled graphene self-repair coating nickel sulfide structure electrode surface of embodiment 1 of the present invention;

Fig. 3 is the TEM picture of the wrinkled graphene-coated nickel sulfide particles on the three-dimensional wrinkled graphene self-repairing coated nickel sulfide structure electrode of Example 1 of the present invention;

Fig. 4 is the TEM picture of the wrinkled graphene on the wrinkled graphene-coated nickel sulfide particle edge on the three-dimensional wrinkled graphene self-repairing coated nickel sulfide structure electrode of Example 1 of the present invention;

5 is a TEM image of the folded graphene curved lattice at the edge of the wrinkled graphene-coated nickel sulfide particles on the three-dimensional wrinkled graphene self-repairing coated nickel sulfide structure electrode according to Example 1 of the present invention;

6 is a synthesis mechanism diagram of a three-dimensional wrinkled graphene self-repairing coated nickel sulfide structure electrode according to Example 1 of the present invention;

Fig. 7 is a three-dimensional wrinkled graphene self-repairing coated nickel sulfide structure electrode in Example 1 of the present invention, and a graph of battery cycle performance of the three-dimensional nickel sulfide electrode at different rates.

detailed description

In order to better understand the present invention, the content of the present invention is further illustrated below in conjunction with the examples, but the content of the present invention is not limited to the following examples.

Embodiment 1: as shown in Figure 6

One, the preparation of graphene dispersion liquid:

a) Add 1g of graphite powder and 23ml of concentrated sulfuric acid in a 250ml Erlenmeyer flask, mix and stir at room temperature for 24 hours;

b) Put the Erlenmeyer flask into a constant temperature water bath, the reaction temperature is 40 degrees Celsius, add 100 mg NaNO ₃ to the dispersion obtained in step a), stir for 5 minutes, then slowly add 1500 mg KMnO ₄ , and keep the solution temperature below 45 degrees Celsius, stir 30 minutes;

c) Add 3ml of deionized water to the dispersion obtained in step b), stir for 5 minutes, then add 3ml of deionized water, then stir for 5 minutes, then add 40ml of deionized water, and stir for 15 minutes;

d) Remove the Erlenmeyer flask from the water bath, add 140ml of deionized water and 10ml of 30% H ₂ O ₂ to terminate the oxidation reaction;

e) The suspension obtained in step d) was washed twice with a 5% HCl solution, then washed with deionized water until neutral, dispersed in 100ml of deionized water, and ultrasonicated for 60 minutes;

f) centrifuge the suspension obtained in step e) at 8000 rpm for 5 minutes, and repeatedly take the supernatant until a uniform graphene dispersion is separated with a concentration of 4.7 mg/ml.

2. Preparation of three-dimensional wrinkled graphene self-healing coated nickel sulfide structure electrode

1) Prepare 50 mL of NaOH solution with a mass fraction of 10%, add 0.25 g of S, 0.65 g of Na ₂ S 9H ₂ O to it, stir in a water bath until an orange-yellow transparent solution is formed, and the temperature of the water bath is 60 degrees Celsius;

2) Add 15 mL of graphene dispersion (concentration is 4.7 mg/mL) to the solution obtained in step 1), and stir with magnetic force for 1 hour;

3) Add 72 mL of dilute hydrochloric acid with a mass fraction of 5% to the solution obtained in step 2), adjust the pH of the solution to 2, a white precipitate precipitates out, and stir magnetically for 1 hour;

4) Suction filtration of the suspension obtained in step 3) to obtain graphene-coated sulfur particles, and drying in air at 70 degrees Celsius for 24 hours;

5) Use a piece of commercial nickel foam (pre-ultrasonic cleaning in alcohol and acetone for 30 minutes, repeat again), the diameter of the disc is 18mm, first soak in 2mol/L dilute hydrochloric acid for 15 minutes, and then soak in alcohol for 10 minutes , then soak in deionized water for 10 minutes, set aside for later use;

6) 40mg of graphene-coated sulfur particles obtained in step 4), and a piece of foamed nickel obtained in step 5) are placed in the inner lining of a 100mL polytetrafluoroethylene reactor, and 40mL of deionized water is added. Under the centigrade degree of hydrothermal reaction 4h, after the completion of the reaction, cool to room temperature;

7) Rinse the three-dimensional wrinkled graphene self-repairing coated nickel sulfide structure electrode obtained in step 6) with alcohol and water, then soak it in 0.048% hydrazine hydrate aqueous solution for 3 hours, and finally place it in the air at 70 degrees Celsius Dry for more than 24 hours.

Taking the three-dimensional wrinkled graphene self-repairing coated nickel sulfide structure electrode of the present invention as an example, its structure and composition are determined by X-ray diffractometer. As shown in Figure 1, the main phase of three-dimensional wrinkled graphene self-healing coated nickel sulfide particles is nickel sulfide, and the impurity phase is nickel sulfide. The peak of nickel sulfide is very consistent with that of JCPDF card No.00-044-1418.

As shown in Figure 2, the field emission scanning electron microscope image shows that the three-dimensional wrinkled graphene self-healing coated nickel sulfide structure electrode surface three-dimensional wrinkled graphene is tightly wrapped on the nickel sulfide surface. As shown in Figure 3, the transmission electron microscope image shows that graphene is wrapped on the surface of nickel sulfide. As shown in Figure 4, the high-resolution transmission electron microscope image shows that the wrinkled graphene is distributed on the edge of nickel sulfide. As shown in Figure 5, the high-resolution TEM image shows the curved lattice of wrinkled graphene.

The three-dimensional wrinkled graphene self-repairing coated nickel sulfide structure electrode obtained in this embodiment is used as the positive electrode, and 1M LiTFSI is dissolved in 1,3-dioxolane (DOL) and dimethylethylene ether (DME) as the positive electrode. Electrolyte, with lithium sheet as the negative electrode, Celgard2325 as the diaphragm, CR2025 stainless steel as the battery shell to assemble into a button lithium ion battery.

As shown in Figure 7, taking the three-dimensional wrinkled graphene self-repairing coated nickel sulfide structure electrode obtained in this example as an example, the battery still maintains a capacity of 500mAhg ^-1 after more than 600 cycles under 8Ag ^-1 constant current charge and discharge. . Under 10Ag ^-1 constant current charge and discharge, after more than 650 cycles, the battery still maintains a capacity of 450mAhg ^-1 . Under 20Ag ^-1 constant current charge and discharge, after 1000 cycles, the battery still maintains a capacity of 350mAhg ^-1 . The above results show that the three-dimensional wrinkled graphene self-healing coated nickel sulfide structure electrode can significantly improve the charge and discharge performance of the battery, and it is a very potential structural electrode.

Example 2:

One, the preparation of graphene dispersion liquid: same as embodiment 1;

2. Preparation of three-dimensional wrinkled graphene self-healing coated nickel sulfide structure electrode

1) Prepare 50mL of NaOH solution with a mass fraction of 10%, add 0.25gS, 0.65gNa ₂ S·9H ₂ O to it, stir in a water bath until an orange-yellow transparent solution is formed, and the temperature of the water bath is between 60 degrees Celsius;

2) Add 10 mL of graphene oxide solution (concentration is about 4.7 mg/mL) to the solution obtained in step 1), and stir with magnetic force for 1 hour;

3) Add about 72 mL of dilute hydrochloric acid with a mass fraction of 5% to the solution obtained in step 2), adjust the pH of the solution to 2, a white precipitate precipitates out, and stir magnetically for 1 hour;

4) Suction filtration of the suspension obtained in step 3) to obtain graphene-coated sulfur particles, and drying in air at 70 degrees Celsius for 24 hours;

5) Use a piece of commercial nickel foam (pre-ultrasonic cleaning in alcohol and acetone for 30 minutes, repeat again), the diameter of the disc is 18mm, first soak in 2mol/L dilute hydrochloric acid for 15 minutes, and then soak in alcohol for 10 minutes , then soak in deionized water for 10 minutes, set aside for later use;

6) 40mg of graphene-coated sulfur particles obtained in step 4), and a piece of nickel foam obtained in step 5), are placed in the inner lining of a polytetrafluoroethylene reactor of 100mL, and 40mL of deionized water is added. Under the centigrade degree of hydrothermal reaction for 4 hours, cool to room temperature after completion of the reaction;

7) Rinse the three-dimensional wrinkled graphene self-repairing coated nickel sulfide structure electrode obtained in step 6) with alcohol and water, then soak it in an aqueous solution of 0.048% hydrazine hydrate for 3 hours, and finally place it in the air at 70 degrees Celsius Dry for more than 24 hours.

Example 3:

One, the preparation of graphene dispersion liquid: same as embodiment 1;

2. Preparation of three-dimensional wrinkled graphene self-healing coated nickel sulfide structure electrode

1) Prepare 50 mL of NaOH solution with a mass fraction of 10%, add 0.25 g of S, 0.65 g of Na ₂ S 9H ₂ O to it, stir in a water bath until an orange-yellow transparent solution is formed, and the temperature of the water bath is between 60 degrees Celsius;

2) Add 5 mL of graphene oxide solution (concentration is about 4.7 mg/mL) to the solution obtained in step 1), and stir magnetically for 1 hour;

3) Add about 72 mL of dilute hydrochloric acid with a mass fraction of 5% to the solution obtained in step 2), adjust the pH of the solution to 2, a white precipitate precipitates out, and stir magnetically for 1 hour;

4) Suction filtration of the suspension obtained in step 3) to obtain graphene-coated sulfur particles, and drying in air at 70 degrees Celsius for 24 hours;

5) Use a piece of commercial nickel foam (pre-ultrasonic cleaning in alcohol and acetone for 30 minutes, repeat again), the diameter of the disc is 18mm, first soak in 2mol/L dilute hydrochloric acid for 15 minutes, and then soak in alcohol for 10 minutes , then soak in deionized water for 10 minutes, set aside for later use;

6) 40mg of graphene-coated sulfur particles obtained in step 4), and a piece of nickel foam obtained in step 5), are placed in the inner lining of a polytetrafluoroethylene reactor of 100mL, and 40mL of deionized water is added. Under the centigrade degree of hydrothermal reaction for 4 hours, cool to room temperature after completion of the reaction;

7) Rinse the three-dimensional wrinkled graphene self-repairing coated nickel sulfide structure electrode obtained in step 6) with alcohol and water, then soak it in an aqueous solution of 0.048% hydrazine hydrate for 3 hours, and finally place it in the air at 70 degrees Celsius Dry for more than 24 hours.

Example 4:

One, the preparation of graphene dispersion liquid: same as embodiment 1;

2. Preparation of three-dimensional wrinkled graphene self-healing coated nickel sulfide structure electrode

1) Prepare 50 mL of NaOH solution with a mass fraction of 10%, add 0.25 g of S, 0.65 g of Na ₂ S 9H ₂ O to it, stir in a water bath until an orange-yellow transparent solution is formed, and the temperature of the water bath is between 70 degrees Celsius;

2) Add 20 mL of graphene oxide solution (concentration is about 4.7 mg/mL) to the solution obtained in step 1), and stir with magnetic force for 1 hour;

3) Add about 72 mL of dilute hydrochloric acid with a mass fraction of 5% to the solution obtained in step 2), adjust the pH of the solution to 2, a white precipitate precipitates out, and stir magnetically for 1 hour;

4) Suction filtration of the suspension obtained in step 3) to obtain graphene-coated sulfur particles, and drying in air at 70 degrees Celsius for 24 hours;

5) Use a piece of commercial nickel foam (pre-ultrasonic cleaning in alcohol and acetone for 30 minutes, repeat again), the diameter of the disc is 18mm, first soak in 2mol/L dilute hydrochloric acid for 15 minutes, and then soak in alcohol for 10 minutes , then soak in deionized water for 10 minutes, set aside for later use;

6) 40mg of graphene-coated sulfur particles obtained in step 4), and a piece of nickel foam obtained in step 5), are placed in the inner lining of a polytetrafluoroethylene reactor of 100mL, and 40mL of deionized water is added. Under the centigrade degree of hydrothermal reaction for 4 hours, cool to room temperature after completion of the reaction;

7) Rinse the three-dimensional wrinkled graphene self-repairing coated nickel sulfide structure electrode obtained in step 6) with alcohol and water, then soak it in an aqueous solution of 0.048% hydrazine hydrate for 3 hours, and finally place it in the air at 70 degrees Celsius Dry for more than 24 hours.

Claims (2)

1. A preparation method for a three-dimensional wrinkled graphene self-repairing coated nickel sulfide structure electrode, comprising the following steps: 1) Prepare 50mL of NaOH solution with a mass fraction of 10%, add 0.25gS, 0.65gNa ₂ S·9H ₂ O to it, stir in a water bath until an orange-yellow transparent solution is formed, and the temperature of the water bath is between 60-80 degrees Celsius; 2) Add 5-20mL of graphene dispersion with a concentration of 4.7mg/mL to the solution obtained in step 1), and stir magnetically for 1 hour; 3) Add 72 mL of dilute hydrochloric acid with a mass fraction of 5% to the solution obtained in step 2), adjust the pH of the solution to 2, a white precipitate is precipitated, and stir magnetically for 1 hour; 4) Suction filtration of the suspension obtained in step 3) to obtain graphene-coated sulfur particles, and drying in air at 70 degrees Celsius for 24 hours; 5) Use a piece of commercial nickel foam with a diameter of 18mm, soak it in 2mol/L dilute hydrochloric acid for 15 minutes, then soak it in alcohol for 10 minutes, then soak it in deionized water for 10 minutes, and reserve it for later use; 6) 40mg of graphene-coated sulfur particles obtained in step 4), and a piece of nickel foam obtained in step 5), are placed in the inner lining of a polytetrafluoroethylene reactor of 100mL, and 40mL of deionized water is added. Under the centigrade degree of hydrothermal reaction for 4 hours, cool to room temperature after completion of the reaction; 7) Rinse the three-dimensional wrinkled graphene self-repairing coated nickel sulfide structure electrode obtained in step 6) with alcohol and water, then soak it in 0.048% hydrazine hydrate aqueous solution for 3 hours, and finally place it in the air at 70 degrees Celsius Dry for more than 24 hours. 2. according to the preparation method of three-dimensional wrinkled graphene self-repair coating nickel sulfide structure electrode according to claim 1, its step 2) described graphene dispersion liquid preparation is as follows: a) Add 1g of graphite powder and 23mL of concentrated sulfuric acid to a 250mL Erlenmeyer flask, mix and stir at room temperature for 24 hours; b) Put the Erlenmeyer flask into a constant temperature water bath, the reaction temperature is 40 degrees Celsius, add 100 mg NaNO ₃ to the dispersion obtained in step a), stir for 5 minutes, then slowly add 1500 mg KMnO ₄ , and keep the solution temperature below 45 degrees Celsius, stir 30 minutes; c) Add 3 mL of deionized water to the dispersion obtained in step b), stir for 5 minutes, then add 3 mL of deionized water, then stir for 5 minutes, then add 40 mL of deionized water, and stir for 15 minutes; d) Remove the Erlenmeyer flask from the water bath, add 140mL of deionized water and 10mL of 30% H ₂ O ₂ to terminate the oxidation reaction; e) The suspension obtained in step d) was washed twice with a 5% HCl solution, then washed with deionized water until neutral, dispersed in 100 mL of deionized water, and ultrasonicated for 60 minutes; f) Centrifuge the suspension obtained in step e) at 8000 rpm for 5 minutes, and repeatedly take the supernatant until a uniform graphene dispersion is separated with a concentration of 4.7 mg/mL.