阅读说明：本技术 一种镍钴双氢氧化物储能电极材料的制备方法 (Preparation method of nickel-cobalt double hydroxide energy storage electrode material ) 是由 胡小颖 南浩善 于 2020-03-13 设计创作，主要内容包括：本发明公开了一种镍钴双氢氧化物储能电极材料的制备方法,采用电化学脱硫装置制备,通过循环伏安法以及恒流源充放电两种方法实现,将镍钴硫化物脱硫转变为镍钴氢氧化物,电化学脱硫装置包括电化学工作站、三电极电解槽、电脑终端和与电化学工作站连接的三电极系统,三电极系统包括通入三电极电解槽电解液内的对电极夹线与对电极、标准电极夹线与标准电极、工作电极夹线与含镍钴硫化物的工作电极。本发明通过以镍钴硫化物为前驱体,通过电化学脱硫法制得了具有絮般细片状形貌的低结晶度镍钴双氢氧化物电极材料,以进一步缩小片状镍钴双氢氧化物尺寸,进一步提高表面储能活性位点数量,进一步提升镍钴双氢氧化物的比电容。(The invention discloses a preparation method of a nickel-cobalt double hydroxide energy storage electrode material, which is prepared by adopting an electrochemical desulfurization device, and is realized by a cyclic voltammetry method and a constant current source charging and discharging method, so that nickel-cobalt sulfide is desulfurized and converted into nickel-cobalt hydroxide, the electrochemical desulfurization device comprises an electrochemical workstation, a three-electrode electrolytic tank, a computer terminal and a three-electrode system connected with the electrochemical workstation, and the three-electrode system comprises a counter electrode clamp wire and a counter electrode which are introduced into electrolyte of the three-electrode electrolytic tank, a standard electrode clamp wire and a standard electrode, and a working electrode clamp wire and a working electrode containing nickel-cobalt sulfide. The nickel-cobalt sulfide is used as a precursor, and the nickel-cobalt double hydroxide electrode material with low crystallinity and a flocculent fine flake shape is prepared by an electrochemical desulfurization method, so that the size of the flake nickel-cobalt double hydroxide is further reduced, the number of surface energy storage active sites is further increased, and the specific capacitance of the nickel-cobalt double hydroxide is further improved.)

1. A preparation method of a nickel cobalt double hydroxide energy storage electrode material is characterized in that an electrochemical desulfurization device is adopted for preparation, and the nickel cobalt sulfide is desulfurized and converted into nickel cobalt hydroxide through two methods of cyclic voltammetry and constant current source charging and discharging, and further used as a positive energy storage material of a super capacitor, the electrochemical desulfurization device comprises an electrochemical workstation, a three-electrode electrolytic tank, a computer terminal and a three-electrode system connected with the electrochemical workstation, the three-electrode system comprises a counter electrode clamp wire and a counter electrode which are led into electrolyte of the three-electrode electrolytic tank, a standard electrode clamp wire and a standard electrode, a working electrode clamp wire and a working electrode containing nickel cobalt sulfide, the electrochemical workstation is electrically connected with a grounding wire, and the computer terminal is provided with operating software which sends cyclic voltammetry commands and constant current source charging and discharging commands to the electrochemical workstation, the preparation method comprises the following steps:

(1) mixing nickel cobalt sulfide (NiCo)₂S₄) The conductive agent (conductive carbon black) and the binder (polyvinylidene fluoride) are loaded on the carbon paper conductive current collector in a mass ratio of 8:1: 1;

(2) taking a current collector loaded with nickel-cobalt sulfide as a working electrode and connecting the current collector with a working electrode clamping line of an electrochemical workstation, connecting a counter electrode with a counter electrode clamping line of the electrochemical workstation, connecting a standard electrode with a standard electrode clamping line, and forming a three-electrode system by taking 2 mol/L alkaline KOH solution with the pH value of 13 as electrolyte;

(3) desulfurization of nickel cobalt sulfide (NiCo2S4) based on cyclic voltammetry to produce nickel cobalt double hydroxide (Ni)₁/₃Co₂/₃(OH)₂) The specific embodiment is as follows: under the condition of room temperature and in the air atmosphere, setting a cyclic voltammetry potential window at 0-0.45V, and repeatedly cycling for 400 circles at the sweeping speed of 25mv/S until the measured cyclic voltammetry curve is superposed with the last cyclic voltammetry curve, so that the nickel cobalt sulfide (NiCo2S4) can be desulfurized to prepare the low-crystallinity nickel cobalt double hydroxide;

(4) nickel-cobalt charging and discharging method based on constant current sourceThe nickel cobalt double hydroxide is prepared by sulfide desulfurization, and the specific implementation scheme is as follows: under the condition of room temperature and in the air atmosphere, setting a cyclic voltammetry potential window at 0-0.415V, and repeatedly cycling for 500 circles under the current density of 5A/g, namely, the nickel cobalt sulfide (NiCo) can be obtained₂S₄) Desulfurizing to obtain low-crystallinity nickel-cobalt double hydroxide;

(5) the obtained nickel cobalt double hydroxide (Ni)₁/₃Co₂/₃(OH)₂) The electrode is the anode material of the finished electrochemical capacitor without further electrode preparation process.

2. The method of claim 1, wherein the electrolyte is KOH, NaOH, L iOH alkaline electrolyte.

3. The method of claim 1, wherein the standard electrode comprises Hg/HgO standard electrode and Hg/HgCl standard electrode₂Standard electrode, Ag/AgCl standard electrode, Hg/HgSO₄Standard electrodes such as standard electrodes and standard hydrogen electrodes.

4. The method for preparing a nickel-cobalt double hydroxide energy storage electrode material as claimed in claim 1, wherein the counter electrode used by the counter electrode wire clamp and the counter electrode comprises a carbon rod and a platinum sheet electrode.

Technical Field

The invention relates to the field of energy storage electrode materials, in particular to nickel cobalt sulfide (NiCo)₂S₄) Preparation of nickel cobalt double hydroxide (Ni) by electrochemical desulfurization₁/₃Co₂/₃(OH)₂) And its application.

Background

With the rapid development of modern society, the demand of human society for energy is increasingly intensified, and the dependence of society on fossil fuels such as coal, petroleum and the like causes a series of problems of environmental pollution and energy shortage. To alleviate environmental and energy problems, people develop a series of clean energy sources such as wind energy, tidal energy, solar energy, etc. However, these energy sources are difficult to be directly applied to social production, and need to be further converted into electric energy for storage and application. However, the problems of low conversion efficiency, unstable current and the like still exist in the conversion and storage process. Among a series of energy storage devices, the electrochemical capacitor has the characteristic of being suitable for variable-current energy storage and can be used as an energy storage device for clean energy power generation. However, in practical application, the electrochemical capacitor still has the defect of low density, and has the problem of poor endurance when being used as a power source of a power source for a long time. In order to further improve the energy density of electrochemical capacitors, research has been focused on the development of energy storage electrode materials.

The nickel-cobalt double hydroxide has good anion exchange performance, adjustable chemical composition, higher redox activity and energy storage capacity, and is widely used as an electrode material of an electrochemical capacitor. The current methods for preparing nickel cobalt double hydroxides mainly comprise the following types: (1) a coprecipitation method; (2) hydrothermal method; (3) a solvothermal method; (4) electrochemical deposition method. In the existing preparation methods of nickel cobalt double hydroxide, the prepared nickel cobalt double hydroxide is mainly flaky, and the flaky size of the flaky nickel cobalt double hydroxide is large, so that the improvement of the specific surface area of the nickel cobalt double hydroxide is restrained. In addition, the nickel-cobalt double hydroxide prepared by the methods has high crystallinity, so that the amount of exposed active sites is small, and the improvement of charge storage performance is further limited.

Electrochemical desulfurization methods are widely used for desulfurization refining of fossil fuels such as coal. Particularly, in the process of coal desulfurization containing pyrite, the coal is placed in an alkaline environment, and the pyrite therein can interact with high-activity groups such as hydroxyl radicals in an alkaline solution so as to oxidize the pyrite into iron hydroxide and sulfate radicals, and the method is only applied to industrial desulfurization at present and is not applied to preparation of electrode materials of nickel-cobalt double hydroxide yet. The application of nickel-cobalt double hydroxide prepared by an electrochemical desulfurization method by taking nickel-cobalt sulfide as a precursor and the technology of electrochemical energy storage are not developed and applied.

The closest prior arts of the same kind in this application are mainly classified into the following two categories: one is electrochemical deposition nickel cobalt double hydroxide which is suitable for preparing electrode material; the other method is the method suitable for electrochemical catalysis normal-temperature normal-pressure diesel oil desulfurization at present.

A preparation technology of electrochemical deposition nickel cobalt double hydroxide suitable for preparing electrode materials, such as a preparation method of a nickel/cobalt/hydroxide composite electrode material mentioned in patent application No. 201910317153.1. The composite electrode material is prepared by performing electrochemical reconstruction on carbon cloth deposited with a nickel-based nano array and a cobalt-based nano array through a cyclic voltammetry, wherein the mass ratio of the nickel-based nano array to the cobalt-based nano array is 1:0.25-2.5, the scanning rate adopted in the cyclic voltammetry is 20-200mV/s, the scanning voltage window is 0-0.5V-0-1.0V (reference Hg/HgO electrode), and the number of scanning cycles is 500-; the electrolyte adopted in the cyclic voltammetry is alkaline electrolyte; the alkaline electrolyte is any one of sodium hydroxide, potassium hydroxide or lithium hydroxide or the combination of any two or three of the sodium hydroxide, the potassium hydroxide or the lithium hydroxide. The electrode material prepared by the method provided by the patent has excellent electrochemical performance, high specific capacitance retention rate and excellent rate performance.

However, the preparation technology of nickel cobalt double hydroxide by electrochemical desulfurization is still unavailable at present, and reference can be made to desulfurization refining of fossil fuels such as coal only, for example, the electrochemical catalysis normal temperature and pressure diesel oil desulfurization method mentioned in patent application No. 201610040678.1. The patent takes oxygen free radicals generated by electrochemical catalytic oxidation as a catalyst, the catalyst reacts with diesel oil and gasoline thiophene catalytic oxidation, and acid gas is generated and discharged, so that low-sulfur oil products with the total desulfurization rate close to 100% are obtained.

Generally, the preparation method of the nickel-cobalt double hydroxide electrode material by electrochemical deposition is widely reported, but most of the precursors adopted by the electrode material are nickel-cobalt alloy, nickel salt or cobalt salt, the nickel-cobalt double hydroxide is generated by the interaction of the nickel-cobalt alloy, the nickel salt or the cobalt salt and hydroxyl in a solution, and the nickel-cobalt double hydroxide prepared by electrochemical desulfurization by taking nickel-cobalt sulfide as the precursor is not yet researched, reported and patented. The existing electrochemical desulfurization technology is only applied to desulfurization refining of fossil fuels such as coal and the like, and is not applied to preparation of electrode materials.

The closest electrochemical deposition technique for nickel cobalt double hydroxide to the present invention still has some problems and disadvantages. If the nickel-cobalt alloy is taken as a precursor, the prepared nickel-cobalt double hydroxide is mainly cubic particles and is not sequentially accumulated on the precursor of the nickel-cobalt alloy, and the prepared nickel-cobalt double hydroxide has the defects of uneven nickel-cobalt atomic ratio, low specific surface area and low effective utilization rate of materials during energy storage due to the alloy segregation phenomenon. Although the nickel salt and the cobalt salt are used as precursors, the atomic ratio of nickel and cobalt in the nickel-cobalt double hydroxide can be effectively regulated, and the energy storage performance of the nickel-cobalt double hydroxide can be further regulated, under an alkaline medium, the nickel-cobalt double hydroxide tends to generate a hexagonal sheet structure, the sheet size is large, the thickness is thick, the further improvement of the specific surface area is not facilitated, and therefore the energy storage efficiency is also low. In addition, after the nickel cobalt double hydroxide is electrochemically deposited, the subsequent heat treatment step is involved to improve the crystallinity of the product of the electrochemical deposition, so that the number of active energy storage sites of the nickel cobalt double hydroxide is further reduced, and the further improvement of the energy storage performance is limited.

An effective solution to the problems in the related art has not been proposed yet.

Disclosure of Invention

The invention aims to provide a preparation method of a nickel-cobalt double hydroxide energy storage electrode material, which solves the problems that nickel-cobalt double hydroxide has large sheet size and thick thickness and high crystallinity and improves the energy storage performance (specific capacitance).

In order to achieve the purpose, the invention provides the following technical scheme: the utility model provides a preparation method of nickel cobalt double hydroxide energy storage electrode material, adopts electrochemical desulphurization device to prepare, realizes through two kinds of methods of cyclic voltammetry and constant current source charge-discharge, changes the nickel cobalt sulphide desulfurization into nickel cobalt hydroxide to further be used as ultracapacitor system's anodal energy storage material, electrochemical desulphurization device includes electrochemical workstation, three-electrode electrolysis trough, computer terminal and the three-electrode system who is connected with electrochemical workstation, three-electrode system is including leading into in three-electrode electrolysis trough electrolyte counter electrode clamp wire and counter electrode, standard electrode clamp wire and standard electrode, working electrode clamp wire and the working electrode that contains nickel cobalt sulphide, electrochemical workstation electricity is connected with the earth connection, computer terminal installs the operating software that sends cyclic voltammetry order and constant current source charge-discharge order to electrochemical workstation, the preparation method comprises the following steps:

(1) mixing nickel cobalt sulfide (NiCo)₂S₄) The conductive agent (conductive carbon black) and the binder (polyvinylidene fluoride) are loaded on the carbon paper conductive current collector in a mass ratio of 8:1: 1;

(2) will be loaded with nickel cobalt sulfide (NiCo)₂S₄) The current collector is used as a working electrode and is connected with a working electrode clamping line of an electrochemical workstation, a counter electrode is connected with a counter electrode clamping line of the electrochemical workstation, a standard electrode is connected with a standard electrode clamping line, and alkaline KOH solution with the pH value of 13 and 2 mol/L is used as electrolyte to form a three-electrode system;

(3) cyclic voltammetry based nickel cobalt sulfide (NiCo)₂S₄) Desulfurizing to obtain Ni-Co double hydroxide (Ni)₁/₃Co₂/₃(OH)₂) The specific embodiment is as follows: under the condition of room temperature and in the air atmosphere, setting the cyclic voltammetry potential window at 0-0.45V, repeatedly circulating for 400 circles at the sweeping speed of 25mv/s until the measured cyclic voltammetry curve is superposed with the last cyclic voltammetry curve, and then obtaining the nickel cobalt sulfide (NiCo) through the reaction of the nickel cobalt sulfide and the nickel cobalt sulfide₂S₄) Desulfurizing to obtain low-crystallinity Ni-Co double hydroxide (Ni)₁/₃Co₂/₃(OH)₂)；

(4) Nickel cobalt sulfide (NiCo) based on constant current source charging and discharging method₂S₄) Desulfurizing to obtain Ni-Co double hydroxide (Ni)₁/₃Co₂/₃(OH)₂) The specific embodiment is as follows: under the condition of room temperature and in the air atmosphere, setting a cyclic voltammetry potential window at 0-0.415V, and repeatedly cycling for 500 circles under the current density of 5A/g, namely, the nickel cobalt sulfide (NiCo) can be obtained₂S₄) Desulfurizing to obtain low-crystallinity Ni-Co double hydroxide (Ni)₁/₃Co₂/₃(OH)₂)；

(5) The obtained nickel cobalt double hydroxide (Ni)₁/₃Co₂/₃(OH)₂) The electrode is the anode material of the finished electrochemical capacitor without further electrode preparation process.

Further, the electrolyte is KOH, NaOH or L iOH alkaline electrolyte.

Further, the standard electrode wire clamp and the standard electrode adopted by the standard electrode comprise Hg/HgO standard electrode and Hg/HgCl standard electrode₂Standard electrode, Ag/AgCl standard electrode, Hg/HgSO₄Standard electrodes such as standard electrodes and standard hydrogen electrodes.

Furthermore, the counter electrode used by the counter electrode wire clamp and the counter electrode comprises a carbon rod and a platinum sheet electrode.

Compared with the prior art, the invention has the following beneficial effects: the electrochemical desulfurization method for preparing the nickel-cobalt double hydroxide is a new technology, successful application on the nickel-cobalt double hydroxide shows that the method not only can be applied to the preparation of the nickel-cobalt double hydroxide electrode material, but also can be further applied to the preparation of other multi-hydroxide by carrying out appropriate potential window adjustment based on the method, has rich market application prospect, has flake-formed flocculent morphology and low crystallinity in terms of the promotion of energy storage sites of the nickel-cobalt double hydroxide, has more energy storage sites with excellent specific capacitance and rate capability compared with the nickel-cobalt double hydroxide which is mainly hexagonal flakes, has large size and large thickness and has high crystallinity and is obtained by electrochemical deposition, and the nickel-cobalt double hydroxide prepared by the electrochemical desulfurization method has large-scale application prospect in factory production, the device for preparing the nickel-cobalt double hydroxide by the electrochemical desulfurization method is simple; in addition, the nickel cobalt sulfide can be artificially synthesized by various synthetic methods such as hydrothermal synthesis, sol-gel synthesis, solid-phase sintering and the like, which are suitable for large-scale production, the synthetic period is short, and in addition, the nickel cobalt sulfide in the nickel cobalt ore also exists in natural conditions, and the purified nickel cobalt sulfide can be used as a raw material for preparing nickel cobalt double hydroxide by electrochemical desulfurization.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

FIG. 1 is a schematic diagram of an electrochemical desulfurization apparatus for preparing a nickel-cobalt double hydroxide energy storage electrode material according to an embodiment of the invention;

FIG. 2 is a scanning electron microscope image of Ni-Co sulfide and Ni-Co double hydroxide prepared by electrochemical desulfurization according to the embodiment of the present invention;

FIG. 3 is a graph of X-ray photoelectron spectroscopy analysis of elemental sulfur in nickel cobalt sulfide and nickel cobalt double hydroxide obtained after electrochemical desulfurization according to an embodiment of the present invention;

FIG. 4 is an X-ray diffraction analysis of elemental sulfur in nickel cobalt sulfide and nickel cobalt double hydroxide produced after electrochemical desulfurization in accordance with an embodiment of the present invention;

FIG. 5 is a chart of the infrared absorption spectra of nickel cobalt sulfide and nickel cobalt double hydroxide produced after electrochemical desulfurization in accordance with an embodiment of the present invention;

FIG. 6 is a Raman scattering spectrum of nickel cobalt sulfide and nickel cobalt double hydroxide produced after electrochemical desulfurization according to an embodiment of the present invention;

FIG. 7 is a graph of constant current source charging and discharging data of nickel cobalt hydroxide after electrochemical desulfurization according to an embodiment of the present invention;

FIG. 8 is a graphical representation of the cycling stability of nickel cobalt hydroxide after electrochemical desulfurization at a current density of 5A/g, in accordance with an embodiment of the present invention.

Reference numerals:

1. an electrochemical workstation; 2. a ground line; 3. a counter electrode wire clamp and a counter electrode; 4. a standard electrode wire clamp and a standard electrode; 5. the working electrode wire clamping and the working electrode containing nickel-cobalt sulfide; 6. a three-electrode electrolytic cell; 7. an electrolyte; 8. and (6) a computer terminal.

Detailed Description

The invention is further described with reference to the following drawings and detailed description: