CN113023704A

CN113023704A - Preparation method of coralline cobalt pyrophosphate supercapacitor electrode material

Info

Publication number: CN113023704A
Application number: CN202110268299.9A
Authority: CN
Inventors: 李文坡; 左秀丽; 王亚
Original assignee: Chongqing University
Current assignee: Chongqing University
Priority date: 2021-03-12
Filing date: 2021-03-12
Publication date: 2021-06-25

Abstract

The patent of the present invention discloses a preparation method of a coral-like cobalt pyrophosphate supercapacitor electrode material, and specifically relates to the technical field of nanomaterials. A preparation method of a coral-like cobalt pyrophosphate supercapacitor electrode material, comprising the following steps: adding a cobalt source and a phosphorus source into a beaker containing ultrapure water, adding a surfactant to the beaker, and magnetically stirring until the solution is mixed uniformly , put the mixed solution and nickel foam in the inner tank of the polytetrafluoroethylene reactor, transfer it to the stainless steel reactor and put it into the oven for reaction; after the reactor is cooled to room temperature, rinse it with ethanol and ultrapure water for many times The nickel foam is finally dried in a vacuum drying oven to obtain the nickel foam; the nickel foam is placed in a tube furnace, under the protection of a nitrogen atmosphere, and calcined at 200-600 ° C, the cobalt pyrophosphate electrode material can be obtained. By adopting the technical scheme of the present invention, a cobalt pyrophosphate electrode material with high crystallinity, unique morphology and excellent performance can be prepared, which can be used as an electrode material for supercapacitors.

Description

Preparation method of coralline cobalt pyrophosphate supercapacitor electrode material

Technical Field

The invention relates to the technical field of nano materials, in particular to a preparation method of a coralliform cobalt pyrophosphate supercapacitor electrode material.

Background

With the rapid development of economy and the consumption of non-renewable energy, people are continuously searching for energy storage devices which can be developed continuously. Thus, clean energy storage devices, such as solar, tidal, wind, geothermal, etc., which are renewable energy sources, are emerging at the forefront of the public. Due to the seasonal, geographical and temporal uncertainty of these renewable energy sources, there is a pressing need to develop reliable, efficient, low-cost energy storage devices. After long-term exploration by researchers, lead-acid batteries and nickel-cadmium-nickel-hydrogen secondary batteries are gradually developed and become the dominant force of energy storage markets at that time. However, the pollution to the ecological environment is serious due to the use of toxic and harmful heavy metals such as lead, cadmium, nickel and the like, and the energy density of the heavy metals still does not reach an ideal value, so that the environmental protection and safety of novel clean energy are not met. The lithium ion batteries that have subsequently emerged are widely reported and commercially produced due to their high energy density, smooth discharge, and wide operating temperature range. Because the low power density of the lithium ion battery cannot meet the requirement of a high-power energy storage device in actual production, researchers explore an energy storage device, namely a super capacitor, which has high power density, high energy density, long cycle life and good rate capability.

The performance of supercapacitors is mainly determined by electrode materials, including electric double layer capacitor electrode materials (activated carbon, graphene, carbon black), pseudocapacitor electrode materials (metal oxides, hydroxides, nitrides, sulfides, phosphides, conducting polymers, etc.). Particularly, the transition metal phosphate material has diversity in structure, can provide rich active sites for reaction, and has strong P-O covalent bond in the structure, so that the material has good cycling stability. Therefore, the transition metal phosphate material is a kind of electrode material with great potential. The two-dimensional nano material is used as the electrode material of the super capacitor, and due to the high specific surface area and the exposed active sites, the charge transfer in the electrolyte is promoted, and the degree of the redox reaction is more favorable.

Disclosure of Invention

The invention aims to provide a preparation method of a coralline cobalt pyrophosphate supercapacitor electrode material, and the cobalt pyrophosphate electrode material with high crystallinity, unique appearance and excellent performance is obtained.

In order to achieve the purpose, the technical scheme of the invention is as follows: a preparation method of a coralline cobalt pyrophosphate supercapacitor electrode material comprises the following steps:

s1, growing cobalt hydrogen phosphate precursor on the foamed nickel current collector

Adding a cobalt source and a phosphorus source into a beaker filled with ultrapure water according to a proper proportion, then adding a surfactant into the beaker, magnetically stirring until the solution is uniformly mixed, wherein the surfactant is polyvinylpyrrolidone, placing the mixed solution and cleaned foam nickel into an inner container of a polytetrafluoroethylene reaction kettle, transferring the inner container into a stainless steel reaction kettle, and placing the stainless steel reaction kettle into an oven for reaction for 20 hours; after the stainless steel reaction kettle is cooled to room temperature, washing the foamed nickel for multiple times by using ethanol and ultrapure water, and finally drying in a vacuum drying oven to obtain the foamed nickel loaded with the cobalt hydrogen phosphate precursor;

s2 preparation of cobalt pyrophosphate on foamed nickel current collector

And (3) putting the foamed nickel loaded with the cobalt hydrogen phosphate precursor in S1 into a tube furnace, heating to 200-600 ℃ at the speed of 10 ℃/min under the protection of nitrogen atmosphere, and calcining to obtain the cobalt pyrophosphate electrode material.

Further, the cobalt source in step S1 is cobalt chloride hexahydrate, the phosphorus source is sodium hexametaphosphate, and the mass ratio of the cobalt source to the phosphorus source is 1: 1.

Further, the amount of the surfactant added was 0.1 g.

Further, the hydrothermal temperature in step S1 was 50 ℃.

Further, the calcination temperature in step S2 was 600 ℃ and the calcination time was 0.5 h.

Further, the cobalt pyrophosphate electrode material is prepared in 1Ag^-1Specific capacitance at current density of 185.3F g^-1。

Compared with the prior art, the beneficial effect of this scheme:

1. the cobalt pyrophosphate prepared by the scheme has a unique coral-shaped morphology structure, the diameter is about 100 nanometers, and the excellent nano-scale coral-shaped structure is beneficial to the effective transmission of ions and charges at an electrode/electrolyte interface.

2. According to the scheme, cobalt pyrophosphate directly grows on the foamed nickel current collector to serve as an electrode, and no binder is used in the process, so that the interface contact resistance is reduced, and the electrochemical performance is improved.

3. The two-step method of the scheme has the advantages of simple and convenient operation, mild conditions and rich raw material sources, and the obtained cobalt pyrophosphate has very high crystallinity.

Drawings

FIG. 1 is an XRD pattern of cobalt pyrophosphate, an electrode material prepared in example 1;

FIG. 2 is an SEM photograph of the electrode material cobalt pyrophosphate prepared in example 1;

FIG. 3 is a constant current charge and discharge curve of the electrode material cobalt pyrophosphate prepared in example 1;

FIG. 4 is a cyclic voltammogram of cobalt pyrophosphate as the electrode material prepared in example 1.

Detailed Description

The present invention will be described in further detail below by way of specific embodiments:

example 1

As shown in figures 1 and 2: a preparation method of a coralline cobalt pyrophosphate supercapacitor electrode material comprises the following steps:

0.238g of CoCl6H₂O and (NaPO)₃)₆Dissolved in a beaker containing 40mL of ultrapure water, then 0.1g of PVP (polyvinylpyrrolidone) was added to the beaker and stirred on a magnetic stirrer for 0.5h, at which time the solution stirred well and the solution was pink. Placing the pink solution and cleaned nickel foam (nickel foam size 1cm x 1cm) in 50mL polytetrafluoroethylene reaction kettle, transferring to stainless steel reaction kettle, screwing down the cover, and placing the stainless steel reaction kettle inAnd (4) an oven, and reacting the pink solution for 20 hours at the temperature of 50 ℃. After the stainless steel reaction kettle is cooled to room temperature, taking out the foamed nickel, washing the foamed nickel for multiple times by using absolute ethyl alcohol and ultrapure water, and finally drying the washed foamed nickel in a vacuum drying oven at 35 ℃ for one night to obtain foamed nickel loaded with a cobalt hydrogen phosphate precursor;

s2 preparation of cobalt pyrophosphate on foamed nickel current collector

And taking out the foamed nickel loaded with the cobalt hydrogen phosphate precursor in the vacuum drying oven, putting the foamed nickel into a porcelain boat, putting the porcelain boat into a tubular furnace, connecting the device, and introducing nitrogen for about 20 minutes. And finally, setting a temperature rise program, raising the temperature to 600 ℃ at the speed of 10 ℃/min for calcining, wherein the calcined test piece is calcined for 30 minutes, and taking out the foamed nickel after the tubular furnace is cooled to the room temperature to obtain the cobalt pyrophosphate electrode material.

Example 2

The present example is different from example 1 only in the calcination temperature, and the tube furnace of step S2 in the present example was heated to 200 ℃ to perform calcination.

Example 3

The present example is different from example 1 only in the calcination temperature, and the tube furnace of step S2 in the present example is heated to 400 ℃ for calcination.

Example 4

The present example is different from example 1 only in the calcination temperature, and the tube furnace of step S2 in the present example is heated to 500 ℃ for calcination.

Electrochemical tests were performed on the cobalt pyrophosphate electrode materials prepared in the above examples 1 to 4, using a conventional beaker type three-electrode system (foamed nickel as a working electrode, platinum as a counter electrode, and saturated calomel as a reference electrode), the electrolyte was a KOH solution with a concentration of 2mol/L, and using CHI760E electrochemical workstation of chenhua in shanghai, the implementation results were as follows:

as shown in FIG. 1, it can be seen from FIG. 1 that the cobalt pyrophosphate synthesized by this method has very good crystallinity and no other impurities, indicating that the phase of the product is single.

As shown in FIG. 2, it is understood from FIG. 2 that cobalt pyrophosphate is coral-shaped and has a uniform size, an average size of about 100nm, and a special coral-shaped nanostructure has many pseudocapacitance active sites, which promotes the ion transport rate at the electrode/electrolyte interface.

As shown in FIGS. 3 and 4, when the current density is 1A g^-1Specific capacitance of 185.3F g^-1And the faradaic reaction of the electrode material can be represented by the following equation:

the foregoing are merely examples of the present invention and common general knowledge of known specific structures and/or features of the schemes has not been described herein in any greater detail. It should be noted that, for those skilled in the art, without departing from the structure of the present invention, several changes and modifications can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicability of the patent. The scope of the claims of the present application shall be determined by the contents of the claims, and the description of the embodiments and the like in the specification shall be used to explain the contents of the claims.

Claims

1. a preparation method of coral-like cobalt pyrophosphate supercapacitor electrode material, is characterized in that: comprise the steps:

S1. Growth of cobalt hydrogen phosphate precursor on foamed nickel current collector

The cobalt source and the phosphorus source are added to a beaker containing ultrapure water in an appropriate proportion, then a surfactant is added to the beaker, and the solution is stirred magnetically until the solution is evenly mixed. The surfactant is selected from polyvinylpyrrolidone. The solution and the cleaned nickel foam were placed in the liner of the PTFE reactor, transferred to the stainless steel reactor and placed in an oven for 20h reaction; after the stainless steel reactor was cooled to room temperature, ethanol and ultrapure water were used for several times. Rinse the nickel foam, and finally dry it in a vacuum drying oven to obtain the nickel foam loaded with the cobalt hydrogen phosphate precursor;

S2. Preparation of cobalt pyrophosphate on nickel foam current collector

Put the nickel foam loaded with cobalt hydrogen phosphate precursor in S1 into a tube furnace, under the protection of nitrogen atmosphere, and heat it up to 200-600 ℃ at a rate of 10 ℃/min for calcination to obtain cobalt pyrophosphate. electrode material.

2. the preparation method of a kind of coral-like cobalt pyrophosphate supercapacitor electrode material according to claim 1, is characterized in that: the described cobalt source of step S1 is cobalt chloride hexahydrate, and described phosphorus source is hexametaphosphoric acid Sodium, the mass ratio of the cobalt source to the phosphorus source is 1:1.

3. the preparation method of a kind of coral-like cobalt pyrophosphate supercapacitor electrode material according to claim 2, is characterized in that: the addition amount of described surfactant is 0.1g.

4. the preparation method of a kind of coral-like cobalt pyrophosphate supercapacitor electrode material according to claim 1, is characterized in that: the hydrothermal temperature of step S1 is 50 ℃.

5 . The method for preparing a coral-like cobalt pyrophosphate supercapacitor electrode material according to claim 1 , wherein the calcination temperature in step S2 is 600° C., and the calcination time is 0.5h. 6 .

6. the preparation method of a kind of coral-shaped cobalt pyrophosphate supercapacitor electrode material according to any one of claims 1-5, it is characterized in that: the specific capacitance of described cobalt pyrophosphate electrode material at 1Ag ^-1 current density is 185.3F g ^-1 .