CN105655152A - Ni-Mn layered double hydroxide@nickel foam@carbon three-dimensional hierarchically-structured electrode material and preparation method thereof - Google Patents

Abstract

The invention discloses a Ni-Mn layered double hydroxide foam nickel-carbon three-dimensional hierarchical structure electrode material and a preparation method thereof. The method of the present invention first uses nickel chloride hexahydrate and anhydrous manganese chloride as nickel source and manganese source respectively, foamed nickel as substrate, and obtains Ni-Mn? LDHNF; followed by glucose or graphene as carbon source, coated Ni-Mn? LDHNF, followed by hydrothermal treatment to obtain Ni-Mn? LDH NFC. The invention adopts a step-by-step hydrothermal-drying method, the preparation process and required equipment are simple, the source of raw materials is abundant and the reaction temperature is low, no high-temperature carbonization is required, and large-scale production is easy to realize; the Ni-Mn obtained by the method of the invention? LDHNFC composites not only have good thermal stability, high degree of crystallinity, large specific surface area, but also have strong shape controllability, which is one of the ideal energy materials.

Description

A Ni-Mn layered double hydroxide foamed nickel-carbon three-dimensional hierarchical structure electrode material and its preparation method

technical field

The invention belongs to the technical field of materials science, and relates to a three-dimensional hierarchical structure composite electrode material, specifically a Ni-Mn layered double hydroxide foamed nickel carbon (Ni-MnLDHNFC) three-dimensional hierarchical structure electrode material and a preparation method thereof .

Background technique

The progress of the development of human society and the increase of energy demand have led to the supply and demand crisis of traditional fossil energy and the deterioration of the environment. Environmental problems such as acid rain and greenhouse gases have become increasingly prominent. It is urgent for people to continuously seek new clean energy. The emergence of supercapacitors and lithium batteries conforms to people's demand for new clean and renewable energy sources (such as solar energy, wind energy, biomass energy, geothermal energy, and tidal energy, etc.). Due to its long cycle life, short charge and discharge time, high energy density, high power density, wide operating temperature range, good reliability and other excellent performance and wide applicability, it has gradually replaced traditional nickel metal hydride batteries, Nickel-cadmium batteries and lead-acid batteries are widely used in various electronic devices in today's information age, such as mobile phones, digital cameras, video cameras and digital processors. In recent years, the application of lithium-ion batteries in a new generation of hybrid electric vehicles (HEV) and pure electric vehicles (HEV) has also attracted increasing attention.

At present, most commercial electrode materials are mainly carbon materials with large specific surface area, but their low energy density limits their large-scale use. However, transition metal oxides and hydroxides store charges differently from carbon materials, and have higher energy density than carbon materials through surface Faraday redox reactions, and their layered structure can provide a very uniform dispersion of transition metal ions, making It has a good application prospect in electrochemistry. However, the double-layer metal hydroxides currently studied in the laboratory also have certain defects: (1) LDH has poor conductivity and low working voltage; (2) a large volume change will occur as the number of charge and discharge increases. , which will greatly reduce the cycle stability of the electrode; (3) when it is used as an electrode material, it must first be glued to a conductive substrate with PTFE, etc., and the operation is complicated; if it is possible to coat a layer of carbon on the LDH, and let the LDH The electrode active material is directly grown on the conductive substrate as an electrode material, which will greatly improve its performance and reduce the production process.

Contents of the invention

In view of the above technical problems, the object of the present invention is to provide a Ni-Mn layered double hydroxide foamed nickel-carbon three-dimensional hierarchical structure electrode material and a preparation method thereof. The method can solve the disadvantages of poor electrical conductivity of the double-layer metal hydroxide LDH in the prior art, adhesives used during use, etc., and will not cause harm to the environment at the same time.

In the present invention, nickel chloride hexahydrate and anhydrous manganese chloride are used as nickel source and manganese source respectively, nickel foam is used as substrate, and Ni-MnLDHNF is obtained after one-step hydrothermal treatment; then glucose or graphene is used as carbon source to coat Ni- MnLDHNF, and then carry out the second step of hydrothermal treatment to obtain Ni-MnLDHNFC. Ni-MnLDHNFC with a three-dimensional hierarchical structure was prepared by a step-by-step hydrothermal-drying method by controlling the Ni-Mn molar ratio, hydrothermal reaction time and temperature, and glucose concentration. The specific technical solution of the present invention is introduced as follows.

The invention provides a method for preparing a Ni-Mn layered double hydroxide foam nickel-carbon three-dimensional hierarchical structure electrode material. The specific steps are as follows:

(1) Pretreatment of nickel foam

(2) Preparation of Ni-MnLDHNF

First, at room temperature, nickel chloride hexahydrate, anhydrous manganese chloride, hexamethylenetetramine and deionized water are mixed uniformly in a container; then, the above mixed solution is moved into a high-pressure reactor, and Wherein adding the foamed nickel that step (1) pretreatment obtains, carries out hydrothermal reaction; After reaction finishes, naturally cools to room temperature, washes foamed nickel; The molar ratio of tetramine and deionized water is (8-11):2:10:5;

(3) Preparation of Ni-MnLDHNFC

First, under room temperature conditions, glucose or graphene and deionized water are stirred and dissolved to form a solution; then the above solution is moved into an autoclave, and the nickel foam obtained in step (2) is added thereto to carry out a hydrothermal reaction; After finishing, naturally cool to room temperature, wash the foamed nickel, and vacuum-dry to obtain a Ni-Mn layered double hydroxide foamed nickel-carbon three-dimensional hierarchical structure electrode material.

In the above step (1), the method for pretreating the foamed nickel is as follows: first cut the foamed nickel, then use deionized water, acetone, ethanol, deionized water to wash ultrasonically, and finally vacuum dry.

In the above step (2), the hydrothermal reaction temperature is 85-95° C., and the reaction time is 5-7 hours.

In the above step (3), the hydrothermal reaction temperature is 175-185° C., and the time is 11-13 hours.

In the above step (3), the glucose is D-(+)-glucose, and the graphene is obtained by reducing graphene oxide prepared by the hummer method.

In the solution made of glucose or graphene and deionized water in the above step (3), the concentration of glucose is 10-20 mg/mL, and the concentration of graphene is 3-10 mg/mL.

The present invention also provides a Ni-Mn layered double hydroxide foam nickel-carbon three-dimensional hierarchical structure electrode material obtained by the above preparation method.

The beneficial effects of the present invention are:

1. The preparation process and required equipment of the present invention are simple, the base nickel foam has good flexibility, abundant sources of raw materials, low reaction temperature, no need for high-temperature carbonization, and is easy to realize large-scale production.

2. The Ni-MnLDHNFC composite material obtained by the method of the present invention fully utilizes the synergistic effect of metal layered double hydroxide, foamed nickel and carbon, overcomes the poor conductivity and cycle performance of simple LDH, and the energy density of individual carbon materials Low disadvantage, not only good thermal stability, high degree of crystallization, large specific surface area, good cycle stability, but also strong shape controllability, high specific capacitance, is one of the ideal energy materials.

Description of drawings

Fig. 1 is the scanning electron micrograph of the Ni-MnLDH obtained in Example 1 at a magnification of 10000.

FIG. 2 is a scanning electron microscope image of Ni-MnLDHNF obtained in Example 1 at a magnification of 7000.

Fig. 3 is a scanning electron micrograph of Ni-MnLDH obtained in Example 2 at a magnification of 20,000.

FIG. 4 is a scanning electron microscope image of Ni-MnLDHNF obtained in Example 2 at a magnification of 5000.

FIG. 5 is a scanning electron micrograph of Ni-MnLDHNFC obtained in Example 3 at a magnification of 10,000.

Fig. 6 is the transmission electron microscope picture of Ni-MnLDHNFC obtained in embodiment 3 under high resolution

Fig. 7 is the electrochemical performance test graph of Ni-MnLDH obtained in Example 3.

Fig. 8 is a scanning electron micrograph of Ni-MnLDHNF obtained in Example 4 at a magnification of 2300.

FIG. 9 is the XRD patterns of Ni-MnLDH and Ni-MnLDHC powders obtained in Example 4.

Fig. 10 is a scanning electron micrograph of the Ni-MnLDHNFC obtained in Example 4 at a magnification of 2000.

detailed description

The present invention will be further described below through specific embodiments in conjunction with the accompanying drawings, but the present invention is not limited.

Example 1

A preparation method of a Ni-MnLDHNFC three-dimensional hierarchical structure electrode material, comprising the steps of:

(1) The pretreatment step of nickel foam is to cut the nickel foam into the shape of 1cm × 3cm × 1cm, ultrasonically wash with deionized water, acetone, ethanol and deionized water successively for 15min, then wash twice with deionized water, Then vacuum-dry at 60° C. for 12 hours; specifically, the mass percent concentration of the acetone is 60-98%, and the ethanol is absolute ethanol.

(2) A step for preparing Ni-MnLDH, at room temperature, according to the molar ratio of 9:2:10:5, nickel chloride hexahydrate, anhydrous manganese chloride, cyclohexamethylenetetramine, deionized Add water into a container, stir magnetically for 30-40 minutes until the mixture is completely uniform, and then move it into a polytetrafluoroethylene-lined stainless steel high-pressure reactor; Put it in an oven at 85°C for 6 hours; then cool it down to room temperature naturally, and wash the nickel foam with deionized water and ethanol for 3-4 times in sequence;

(3) In the step of preparing Ni-MnLDHNFC, a certain amount of glucose and deionized water are added to a container at room temperature, and magnetically stirred for 10-20 minutes until completely dissolved to obtain a glucose solution with a concentration of 10 mg/ml, and then Move it into a polytetrafluoroethylene high-pressure reactor; put the nickel foam obtained in step 2) obliquely in the reactor, tighten it and place it in an oven at 185°C for 12 hours, then cool it down to room temperature naturally, and use deionized water and Wash the nickel foam 3-4 times with ethanol, and dry it in vacuum at 60°C for 12 hours.

Using a field emission scanning electron microscope (German Zeissultra55) instrument, the Ni-MnLDH powder obtained above is scanned at a magnification of 10000, and the scanning electron microscope image of the gained is as shown in Figure 1, and it can be seen from Figure 1 that the petal shape of the composite material structure, thus indicating the successful preparation of Ni-MnLDH; at a magnification of 7000, the Ni-MnLDHNF three-dimensional material obtained above was scanned, and the obtained scanning electron microscope image is shown in Figure 2, from which it can be seen that Ni -MnLDH is vertically and uniformly distributed on the surface of nickel foam, which indicates that the Ni-MnLDHNF three-dimensional hierarchical structure material has been successfully prepared.

Example 2

A kind of preparation method of Ni-MnLDHNFC three-dimensional hierarchical structure electrode material, comprises the following steps: (1) the pretreatment step of nickel foam, the nickel foam is cut into the shape of 1cm * 3cm * 1cm, successively with deionized water, acetone, ethanol 1. Ultrasonic washing with deionized water for 15 minutes each, and then washing twice with deionized water, and then vacuum drying at 60°C for 12 hours;

(2) A step for preparing Ni-MnLDH, at room temperature, according to the molar ratio of 8:2:10:5, nickel chloride hexahydrate, anhydrous manganese chloride, cyclohexamethylenetetramine and deionized water Add it into a container, stir magnetically for 30-40min until the mixture is completely uniform, and then transfer it into a polytetrafluoroethylene-lined stainless steel high-pressure reactor; Put it into a 95°C oven to react for 6 hours; take it out and cool it down to room temperature naturally, and wash the nickel foam with deionized water and ethanol for 3-4 times in sequence;

(3) In the step of preparing Ni-MnLDHNFC, a certain amount of glucose and deionized water are added to a container at room temperature, and magnetically stirred for 10-20 minutes until completely dissolved to obtain a glucose solution with a concentration of 13mg/ml, and then Move it into a polytetrafluoroethylene high-pressure reactor; place the nickel foam obtained in step 2) obliquely in the reactor, tighten it and put it in an oven at 175°C for 12 hours, take it out and cool it to room temperature naturally, and then wash it with deionized water Wash the nickel foam with ethanol for 3-4 times, and dry it in vacuum at 60°C for 12 hours.

Using a field emission scanning electron microscope (German Zeissultra55) instrument, the Ni-MnLDH powder obtained above is scanned at a magnification of 20,000, and the scanning electron microscope image of the gained is as shown in Figure 3. From Figure 3, it can be seen that the petal shape of the composite material structure, thus indicating that Ni-MnLDH was successfully prepared; the Ni-MnLDHNF three-dimensional material obtained above was scanned at a magnification of 5000, and the obtained scanning electron microscope image is shown in Figure 4, from which it can be seen that Ni-MnLDH Accumulated on the surface of nickel foam, the distribution is uneven, but it can be seen that the Ni-MnLDHNF three-dimensional hierarchical structure material has been successfully prepared.

Example 3

A preparation method of a Ni-MnLDHNFC three-dimensional hierarchical structure electrode material, comprising the steps of:

(1) The pretreatment step of nickel foam is to cut the nickel foam into the shape of 1cm × 3cm × 1cm, ultrasonically wash with deionized water, acetone, ethanol and deionized water successively for 15min, then wash twice with deionized water, Then vacuum dry at 60°C for 12 hours;

(2) A step for preparing Ni-MnLDH, at room temperature, according to the molar ratio of 10:2:10:5, nickel chloride hexahydrate, anhydrous manganese chloride, cyclohexamethylenetetramine, deionized water Add it into a container according to the molar ratio of 10:2:10:5, stir magnetically for 30-40min until the mixture is completely uniform, and then transfer it into a polytetrafluoroethylene-lined stainless steel autoclave; then pretreat the foam obtained in step 1) Nickel is placed in the reactor at a slant, tightened and placed in an oven at 85°C for 6 hours; after taking it out, cool it down to room temperature naturally, and wash the nickel foam 3-4 times with deionized water and ethanol in sequence;

(3) In the step of preparing Ni-MnLDHNFC, a certain amount of graphene and deionized water are added to a container at room temperature, and magnetically stirred for 10-20 minutes until completely dissolved to obtain a graphene solution with a concentration of 5 mg/ml , and then moved it into a polytetrafluoroethylene high-pressure reactor; put the nickel foam obtained in step 2) obliquely in the reactor, tighten it and place it in an oven at 185°C for 12 hours, take it out and cool it to room temperature naturally, and use it in sequence Wash the nickel foam 3-4 times with ionized water and ethanol, and dry it under vacuum at 60°C for 12 hours.

FIG. 5 is a scanning electron micrograph of the obtained Ni-MnLDHNFC at a magnification of 10,000. It can be seen from Figure 5 that graphene is successfully coated on Ni-MnLDHNF, and the sheet-like petals are in the state of being coated with carbon, but the sheet-like structure can still be clearly seen; Figure 6 is the obtained high The transmission electron microscope figure under resolution, can find out very regular lattice structure; Fig. 7 is Ni-MnLDH electrochemical performance test figure, can find out from Fig. 7 cyclic voltammogram, three-dimensional hierarchical composite electrode material of the present invention is in There are a pair of obvious redox peaks at different scanning speeds, thus verifying the redox reaction.

Example 4

A preparation method of a Ni-MnLDHNFC three-dimensional hierarchical structure electrode material, comprising the steps of:

(1) The pretreatment step of nickel foam is to cut the nickel foam into the shape of 1cm × 3cm × 1cm, ultrasonically wash with deionized water, acetone, ethanol and deionized water successively for 15min, then wash twice with deionized water, Then vacuum dry at 60°C for 12 hours;

(2) A step for preparing Ni-MnLDH, at room temperature, according to the molar ratio of 11:2:10:5, nickel chloride hexahydrate, anhydrous manganese chloride, cyclohexamethylenetetramine, deionized water Add it into a container, stir magnetically for 30-40min until the mixture is completely uniform, and then transfer it into a polytetrafluoroethylene-lined stainless steel high-pressure reactor; Put it into a 90°C oven for 6 hours; take it out and cool it down to room temperature naturally, and wash the foamed nickel 3-4 times with deionized water and ethanol in sequence;

(3) In the step of preparing Ni-MnLDHNFC, a certain amount of glucose and deionized water are added to a container at room temperature, and magnetically stirred for 10-20 minutes until completely dissolved to obtain a glucose solution with a concentration of 20 mg/ml, and then Move it into a polytetrafluoroethylene high-pressure reactor; place the nickel foam obtained in step 2) obliquely in the reactor, tighten it and put it in an oven at 175°C for 12 hours, take it out and cool it to room temperature naturally, and then wash it with deionized water Wash the nickel foam with ethanol for 3-4 times, and dry it in vacuum at 60°C for 12 hours.

The above-mentioned Ni-MnLDHNF three-dimensional material was scanned at a magnification of 2300, and the resulting scanning electron microscope image is shown in Figure 8. From Figure 8, it can be seen that Ni-MnLDH is evenly distributed on the foamed nickel surface, thus indicating the success of the process. The Ni-MnLDHNF three-dimensional hierarchical structure material was prepared, but there were too many petals stacked on it. Fig. 9 is the XRD patterns of Ni-MnLDH and Ni-MnLDHC powders scraped from nickel foam. It can be seen from Fig. 9 that the composite material was successfully prepared and has good crystallinity. Figure 10 is a scanning electron micrograph of the obtained Ni-MnLDHNFC at a magnification of 2000. It can be seen from Figure 10 that glucose is successfully coated on Ni-MnLDHNF. However, glucose has completely covered Ni-MnLDH.

In summary, the Ni-MnLDHNFC with different morphology obtained by the preparation method of a Ni-MnLDHNFC three-dimensional hierarchical structure electrode material of the present invention affects their different electrochemical properties. Under the condition of 1mol/LKOH electrolyte, use The electrochemical performance of the three-electrode system was tested on the electrochemical workstation and the blue electric system. The prepared Ni-MnLDHNF electrode with the best electrochemical performance has 1100mAhg ^-1 when charging and discharging at a constant current of 500mAg ^-1 , but due to the During the process, its volume will change significantly. After 2090 cycles, the specific capacity will decrease significantly, and the rate performance will drop significantly under high current density; while the Ni-MnLDHNFC coated with a certain amount of glucose or graphene will The hierarchical structure electrode material has 1900mAhg ^-1 when charging and discharging at a constant current of ^{500mAg -1} , and after 2090 cycles, it still maintains a specific capacity of nearly 80%, and has good cycle stability. Under the density, it still maintains nearly 70% of the capacitance, has a good rate performance, and makes full use of the synergy of the large surface area of the three-dimensional network of nickel foam, carbon materials, and transitional metal layered double hydroxides. At the same time Overcome the shortcomings of a single material as an electrode.

The above content is only a specific enumeration of the embodiments of the present invention, and any equivalent transformation made according to the technical solution of the present invention shall fall within the protection scope of the present invention.

Claims (7)

1. a preparation method of Ni-Mn layered double hydroxide foamed nickel-carbon three-dimensional hierarchical structure electrode material, is characterized in that, concrete steps are as follows: (1) pretreatment is carried out to nickel foam; (2) Preparation of Ni-MnLDHNF First, at room temperature, nickel chloride hexahydrate, anhydrous manganese chloride, hexamethylenetetramine and deionized water are mixed uniformly in a container; then, the above mixed solution is moved into a high-pressure reactor, and Wherein adding the foamed nickel that step (1) pretreatment obtains, carries out hydrothermal reaction; After reaction finishes, naturally cools to room temperature, washes foamed nickel; The molar ratio of tetramine and deionized water is (8-11):2:10:5; (3) Preparation of Ni-MnLDHNFC First, under room temperature conditions, glucose or graphene and deionized water are stirred and dissolved to form a solution; then the above solution is moved into an autoclave, and the nickel foam obtained in step (2) is added thereto to carry out a hydrothermal reaction; After finishing, naturally cool to room temperature, wash the foamed nickel, and vacuum-dry to obtain a Ni-Mn layered double hydroxide foamed nickel-carbon three-dimensional hierarchical structure electrode material. 2. preparation method as claimed in claim 1, it is characterized in that, in step (1), the method that nickel foam is carried out to pretreatment is as follows: first cut foam nickel into sheet, then use deionized water, acetone, ethanol, Ultrasonic washing with deionized water, and finally vacuum drying. 3. The preparation method according to claim 1, characterized in that, in step (3), the hydrothermal reaction temperature is 85-95° C., and the reaction time is 5-7 hours. 4. The preparation method according to claim 1, characterized in that, in step (3), the hydrothermal reaction temperature is 175-185° C., and the time is 11-13 hours. 5. The preparation method according to claim 1, wherein in step (3), glucose is D-(+)-glucose, and graphene is obtained by reducing graphene oxide prepared by hummer method. 6. preparation method as claimed in claim 1, is characterized in that: in step (3), in the solution that glucose or graphene and deionized water are made, the concentration of glucose is 10-20mg/mL, the concentration of graphene 3-10mg/mL. 7. The Ni-Mn layered double hydroxide foam nickel-carbon three-dimensional hierarchical structure electrode material obtained by the preparation method according to any one of claims 1-6.