CN108963225B - Ni3S2/MnO composite material, preparation method thereof and application thereof in aqueous alkaline battery - Google Patents

Abstract

The invention relates to Ni₃S₂/MnO composite material, preparation method thereof and application thereof in aqueous alkaline batteries, and Ni₃S₂the/MnO compound is carbon paper loaded with Ni₃S₂Active material of MnO, Ni₃S₂The shape of the/MnO active substance is cauliflower-shaped, and the loading capacity of the active substance is 1.5-8 mgcm^‑2. Through a simple electrodeposition method, a precursor is generated on carbon paper in one step, and then the precursor is calcined to obtain a final product Ni₃S₂a/MnO complex. The obtained composite material has large specific surface area, and the rate capability and the cycling stability of the material are promoted. In aqueous alkaline cell application testing, Ni₃S₂the/MnO composite material shows excellent rate capability, 15A g^‑1Still has 30mAh g under the current density^‑1The mass to capacity ratio of (d); shows good cycle stability during long cycle charge and discharge tests at 2A g^‑1After charging and discharging for 450 times under the current density, the specific capacity can still maintain 85.1mAh g^‑1Corresponding to 97.5% of the initial specific capacity and maintaining a coulombic efficiency of nearly one hundred percent throughout the process.

Description

Ni3S2/MnO composite material, preparation method thereof and application thereof in aqueous alkaline battery

The technical field is as follows:

the invention relates to Ni₃S₂A/MnO composite material, a preparation method thereof and application thereof in a water system alkaline battery belong to the technical field of electrochemistry.

Background art:

the lithium ion battery has large capacity and high efficiency, so that the life quality of people is greatly improved, and convenience is brought. With the news of more and more explosion and burning of the batteries, people begin to worry and question the safety of the lithium ion batteries. Flammable and explosive electrolytes, severe assembly conditions and high raw material prices all force people to look at other types of energy storage devices. The aqueous battery replaces the organic electrolyte widely used at present with an aqueous solution, has the advantages of low cost, high safety performance and the like, and can effectively solve the problems. This allows the water-based battery to achieve higher power density because the aqueous solution possesses better ion conductivity properties.

LiMn from the first money of 1994₂O₄Is a positive electrode active material, VO₂Since the research and report on aqueous lithium ion batteries as negative electrode active materials became available, great efforts have been made to develop aqueous lithium/sodium ion batteries and a great breakthrough has been made. In recent years, researchers have successively discovered LiFePO₄,LiTi₂(PO4)₃,Na_0.44MnO₂And the like, but the materials cannot be produced and utilized on a large scale, and the distance from the realization of large-scale commercial application is long. Therefore, many researchers have turned their eyes back to the batteries that have been commercialized.

Among the commercial water-based batteries that are currently available, the most popular in the market are lead-acid batteries and Ni — Zn batteries. Lead-acid batteries are always in the form of leaders in the world battery market due to the mature preparation process. And the alkaline Ni-Zn battery is more competitive in energy density and power density than the lead-acid battery due to the output voltage of up to 1.8V. However, current commercial Ni-Zn cells, typically using beta-Ni (OH)₂As a positive electrode material, the lithium-zinc-nickel-zinc alloy anode material cannot meet the requirements of people in the aspects of cycle life, energy density and the like, and is the main reason that the alkaline Ni-Zn battery lags behind the lead-acid battery.

In recent years except for Ni (OH)₂Besides the modification studies, researchers have looked at other materials, and nickel-based sulfides are superior. This is mainly due to the fact that nickel-based sulphides possess better electronic conductivity, especially Ni, than oxides₃S₂. However, at present, Ni₃S₂Many studies have been made on supercapacitors and the like, and reports on the use of the supercapacitors as positive electrode materials for aqueous alkaline batteries have been very rare. Despite Ni₃S₂The conductivity of the material is good, but the electrochemical performance of the material cannot be compared with that of a carbon material and a metal conductor, and at present, the material is usually compounded with materials with high conductivity, such as the carbon material, foamed nickel and the like; or by constructing a special shape to further increase Ni₃S₂The electrochemical performance of (2). (see electrochimica acta 2017,251,235; adv. energy mater.2017,7,1700983; j. mater. chem.a 2015,3,16150), although the electrochemical performance can be improved to some extent by the recombination energy, the electrochemical performance is still not high, and the current recombination method is complicated and the obtained composite material is unstable.

The invention content is as follows:

aiming at the defects of the prior art, the invention provides Ni₃S₂a/MnO composite material, a preparation method thereof and application thereof in a water system alkaline battery.

Summary of the invention:

the invention further generates Ni-Mn precursor on the carbon paper by a simple electrodeposition method, and then obtains Ni after further calcination₃S₂Composite of/MnO, Ni₃S₂the/MnO compound is carbon paper loaded with Ni₃S₂Active material of MnO, Ni₃S₂the/MnO active substance is in the form of cauliflower, the composite is used in the application test of the water system alkaline battery, Ni₃S₂the/MnO composite material shows excellent rate capability at 15Ag^-1Still has 30mAh g under the current density^-1The mass to capacity ratio of (d); shows good cycle stability during long cycle charge and discharge tests at 2A g^-1After charging and discharging for 450 times under the current density, the specific capacity can still maintain 85.1mAh g^-1Corresponding to 97.5% of the initial specific capacity and maintaining a coulombic efficiency of nearly one hundred percent throughout the process.

The technical scheme of the invention is as follows:

ni₃S₂a/MnO composite of said Ni₃S₂the/MnO compound is carbon paper loaded with Ni₃S₂Active material of MnO, Ni₃S₂The shape of MnO active substance is cauliflowerThe active material loading amount is 1.5-8 mgcm^-2。

More preferably, the active material is supported at 4mgcm^-2。

Ni of the invention₃S₂the/MnO composite material is prepared by loading a material precursor on a carbon paper conductive current collector by an electroplating method, and then sintering at high temperature to obtain the carbon paper loaded with the cauliflower-shaped active substance, wherein no conductive carbon black and no binder are added. The interface resistance between material particles and between particles and the conductive current collector is reduced; the proportion of the useless mass of the electrode is reduced, and the possibility of commercializing the material is increased.

Ni as above₃S₂The preparation method of the/MnO composite material comprises the following steps:

with NiCl₂、MnCl₂The mixed solution of thiourea and the electrolyte is used, active substances are electrodeposited on the surface of the carbon paper by an electrodeposition method, a precursor product is obtained after washing and drying, and then high-temperature calcination is carried out in an inert atmosphere to obtain Ni₃S₂a/MnO composite material.

Preferably according to the invention, NiCl is present in the mixed solution₂Has a concentration of 3 to 15mmol L^-1，MnCl₂The concentration of (A) is 2.5-10 mmol L^-1The concentration of thiourea is 0.25-1 mol L^-1。

Further preferably, NiCl is mixed in the solution₂In a concentration of 7.5mmol L^-1，MnCl₂In a concentration of 5mmol L^-1The concentration of thiourea was 0.5mol L^-1。

According to the invention, the electro-deposition voltage is a constant voltage of-0.8V to-0.9V, and the electro-deposition time is 30min to 120 min.

Most preferably, the electrodeposition voltage is a constant voltage of-0.85V, and the electrodeposition time is 60 min.

Preferably, according to the invention, during electrodeposition, the carbon paper is used as a working electrode, the platinum mesh electrode is used as a counter electrode, and the calomel electrode is used as a reference electrode.

According to the invention, the preferable inert atmosphere is Ar gas, the high-temperature calcination temperature is 350-550 ℃, and the calcination time is 1-3 hours.

Further preferably, the high-temperature calcination temperature is 400 ℃ and the calcination time is 2 hours.

Preferred embodiment of the present invention, Ni₃S₂The preparation method of the/MnO composite material comprises the following steps:

with NiCl₂、MnCl₂Taking a mixed solution of thiourea and the electrolyte, electrodepositing the carbon paper at a constant potential of-0.85V to electrodeposit active substances on the surface of the carbon paper, washing and drying to obtain a precursor product, and calcining for 2 hours at 400 ℃ in an Ar atmosphere to obtain Ni₃S₂a/MnO composite material.

Preferably, according to the invention, the carbon fibers of the carbon paper have a diameter of 7 to 9 μm.

Ni as above₃S₂The application of the/MnO composite material is applied to a water-based alkaline battery and used as a positive electrode material.

The principle of the invention is as follows:

the carbon paper is selected as a current collector, and the carbon paper is a basic composition structure of carbon fiber, wherein the diameter of the carbon fiber is about 8 mu m. The surface is rough, it can be fully contacted with electrolyte in the process of electrodeposition, and it provides a large surface area for Ni₃S₂MnO attachment. And the excellent conductivity of the carbon fiber is beneficial to the transfer of charges on the surfaces of electrolyte and carbon paper, so that the electrochemical reaction in the electrodeposition process is smoothly carried out. In addition, the transmission efficiency of electrons between the current collector and the active substance is higher without the obstruction of the binder, so that the rate capability and the cycling stability of the battery are comprehensively improved. Meanwhile, the appearance of the precursor material in the electroplating process becomes fluffy and is tightly wrapped on the surface of the carbon fiber due to the existence of MnO, so that the direct contact of the bare carbon fiber and the aqueous solution is reduced, the oxygen evolution rate of the battery is reduced, and the high coulomb efficiency in the battery circulation process is ensured.

Ni of the invention₃S₂the/MnO composite material has the following remarkable characteristics:

(1) the invention adopts a simple electrodeposition method to produce carbon paper in one stepForming a precursor, and further calcining to obtain the final product Ni₃S₂a/MnO complex. In aqueous alkaline cell application testing, Ni₃S₂the/MnO composite material shows excellent rate capability, 15A g^-1Still has 30mAh g under the current density^-1The mass to capacity ratio of (d); shows good cycle stability during long cycle charge and discharge tests at 2A g^-1After charging and discharging for 450 times under the current density, the specific capacity can still maintain 85.1mAh g^-1Corresponding to 97.5% of the initial specific capacity and maintaining a coulombic efficiency of nearly one hundred percent throughout the process.

(2) The material of the invention directly loads the precursor material on the current collector through one-step electroplating reaction, and then is sintered at a high temperature for a short time, thus being simple and easy to operate.

(3) The shape of the invention is granular cauliflower shape, the specific surface area is large, and the invention expresses excellent rate capability and cycling stability in battery test.

(4) The invention does not add conductive carbon black and binder, reduce the interface resistance between material particles and between particles and conductive current collector; the proportion of the useless mass of the electrode is reduced, and the possibility of commercializing the material is increased.

Description of the drawings:

FIG. 1 shows Ni obtained in example 1 of the present invention₃S₂Mn-free Mn in the/MnO composite (S1) and the unsintered precursor Material of comparative example 1 (S2) and the plating bath of comparative example 2²⁺Prepared pure Ni₃S₂XRD contrast pattern of material (S3).

FIG. 2 shows Ni obtained in example 1 of the present invention₃S₂Mn-free Mn in the/MnO composite (S1) and the unsintered precursor Material of comparative example 1 (S2) and the plating bath of comparative example 2²⁺Prepared pure Ni₃S₂Scanning electron micrographs of the material (S3). Wherein, the pictures a and b are cauliflower morphology Ni₃S₂SEM photograph of/MnO composite Material (S1), C, d are SEM photographs of the unsintered precursor Material (S2) of comparative example 1, and e, f are SEM photographs of Mn-free plating bath of comparative example 2²⁺Is made ofPure Ni thus obtained₃S₂Scanning electron micrograph of material (S3).

FIG. 3 shows Ni obtained in example 1 of the present invention₃S₂Elemental mapping of/MnO composite (S1) versus unsintered precursor material of comparative example 1 (S2). Wherein a is cauliflower morphology Ni₃S₂The element map of the/MnO composite material (S1), and b is the element map of the precursor material which is not sintered (S2).

FIG. 4 shows Ni obtained in example 1 of the present invention₃S₂The sum of cyclic voltammetry curve, charge-discharge curve and rate performance of the/MnO composite material (S1) is 2A g^-1Cycling performance plot at current density. Wherein, a is a cyclic voltammogram, b is a charge-discharge curve, c is a multiplying power performance curve, d is a current density of 2A g^-1Cyclic performance graph of time.

FIG. 5 is a plot of cyclic voltammogram, charge-discharge curve, rate capability at 2A g for the unsintered precursor material (S2) of comparative example 1^-1Cycling performance plot at current density. Wherein, a is a cyclic voltammogram, b is a charging and discharging curve, and c is a current density of 10A g^-1Cyclic performance graph of time.

FIG. 6 shows Mn-free electroplating solution of comparative example 2²⁺Prepared pure Ni₃S₂The cyclic voltammetry curve, charge-discharge curve and rate performance of the material (S3) are in a range of 2A g^-1Cycling performance plot at current density. Wherein, a is a cyclic voltammogram, b is a charge-discharge curve, c is a multiplying power performance curve, d is a current density of 2A g^-1Cyclic performance graph of time.

The specific implementation mode is as follows:

the invention is explained in more detail below with reference to the figures and examples.

The raw materials in the examples are all commercial products.

Example 1

Ni₃S₂The preparation method of the/MnO composite material comprises the following steps:

with NiCl₂、MnCl₂The mixed solution of thiourea and electrolyte is used as the mixed solutionNiCl in liquid₂In a concentration of 7.5mmol L^-1， MnCl₂In a concentration of 5mmol L^-1The concentration of thiourea was 0.5mol L^-1Electrodepositing carbon paper for 60min under a constant potential of-0.85V to electrodeposit active substances on the surface of the carbon paper, washing and drying to obtain a precursor product, and calcining for 2 hours at 400 ℃ in an Ar atmosphere to obtain Ni₃S₂the/MnO composite material (S1). The mass of the active substance on the carbon paper is 4mg cm-²。

Produced Ni₃S₂The XRD pattern and scanning electron microscope of the/MnO composite material (S1) are shown in figures 1 and 2, and as can be seen from figure 2, the morphology of the material presents the shape of granular combined cauliflower and is densely coated on the surface of carbon fiber, and XRD tests respectively comprise carbon paper and Ni₃S₂And MnO with three different characteristic peaks, Mn element can be observed by element mapping.

Comparative example 1

A method of preparing an unsintered precursor material (S2), comprising the steps of:

with NiCl₂、MnCl₂The mixed solution of thiourea and NiCl is used as electrolyte₂In a concentration of 7.5mmol L^-1， MnCl₂In a concentration of 5mmol L^-1The concentration of thiourea was 0.5mol L^-1And performing electrodeposition on the carbon paper for 60min at a constant potential of-0.85V to electrodeposit active substances on the surface of the carbon paper to obtain a precursor material (S2). The mass of active substance on the carbon paper is 4mg cm^-2。

The XRD pattern and the scanning electron microscope of the prepared unsintered precursor material (S2) are shown in figures 1 and 2, and as can be seen from figure 2, the morphology of the material presents a cauliflower shape and is densely coated on the surface of carbon fiber, an XRD test only has a characteristic peak of carbon paper, and Mn element can be observed through element mapping.

Comparative example 2

The electroplating solution does not contain Mn²⁺Prepared pure Ni₃S₂A method of preparing a material (S3), comprising the steps of:

with NiCl₂The mixed solution of the NiC and the thiourea is used as electrolyte, and the NiC in the mixed solutionl₂In a concentration of 7.5mmol L^-1The concentration of thiourea was 0.5mol L^-1The carbon paper was electrodeposited for 60min at a constant potential of-0.85V. After a certain period of time, washing and drying were carried out to obtain a precursor product, which was then calcined at 400 ℃ for 2 hours (Ar atmosphere) to obtain a final product (S3). The mass of active substance on the carbon paper is 4mg cm^-2。

Obtained Ni₃S₂The XRD pattern and scanning electron microscope of the material (S3) are shown in figures 1 and 2, and as can be seen from figure 2, the morphology of the material presents a nanometer flower shape and is coated on the surface of carbon fiber, but the coating is not dense enough, and XRD tests respectively comprise carbon paper and Ni₃S₂Two different characteristic peaks.

Performance testing

First, cauliflower morphology Ni prepared in example 1₃S₂Mn-free Mn in the/MnO composite (S1) and the unsintered precursor Material of comparative example 1 (S2) and the plating bath of comparative example 2²⁺Prepared pure Ni₃S₂XRD measurements were performed on a sample of material (S3) and the diffraction pattern is shown in fig. 1. from fig. 1, it can be seen that all three materials have the characteristic peaks of carbon paper, indicating that the current collectors are carbon paper and no decomposition or phase change occurs during the whole process. In contrast to the S2 sample, the S1 sample has significantly improved crystallinity because the precursor reacts further and recrystallizes after the high temperature treatment process. In addition to the graphite peak of the carbon paper, hexagonal Ni was observed in the figure₃S₂(JCPDS card No.: 30-0863) and cubic MnO (JSPDS card No.: 06-0592) diffraction peaks. This indicates that the product is Ni₃S₂And MnO. For the S2 sample, only characteristic peaks of carbon paper were observed, indicating Ni₃S₂MnO does not exist on the surface of the carbon paper in a crystalline form, and the general electrochemical performance of the material with poor crystallinity of the de-intercalation mechanism material is poor, which is consistent with the subsequent electrochemical test result. The S3 sample, due to high temperature calcination, showed very good crystallinity from the XRD test results and had Ni₃S₂However, since Mn element is not contained in the raw material, a characteristic peak of MnO is not observed.

FIG. 2 is a scanning electron micrograph of the three materials, and it can be seen from a that, compared with the complete cauliflower-like morphology of the precursor S2 sample (b picture), the basic morphology of the S1 sample is still cauliflower-like after calcination and is tightly wrapped on the surface of the carbon fiber. Shows that the high temperature treatment does not result in Ni₃S₂The MnO is separated from the carbon fiber, and the combination of the MnO and the carbon fiber is stable. However, the petal-shaped wrinkles disappear and become extremely small spherical particles. This is because as the temperature increases, the original precursor material reacts further and agglomerates, and the wrinkles eventually become small spherical particles. c shows that the plating bath does not contain Mn²⁺Prepared pure Ni₃S₂Sample of material (S3). Unlike composites, Ni₃S₂The morphology of (1) is 100-200nm nanoflower, and the flower-like morphology is still maintained after calcination. And a lower contrast, indicating a thinner overall material. This means that Ni₃S₂Neutralizing OH in an electrolyte^-The contact area of (a) is larger, and the transmission path of ions and electrons is also narrower. And carbon fiber grown nanoflower Ni₃S₂But the coating is not dense enough. Both of which show poor electrochemical performance and low coulombic efficiency.

FIG. 3 shows the cauliflower morphology Ni prepared in example 1₃S₂Elemental mapping of/MnO composite (S1) and unsintered precursor material (S2) samples. It is clear from the figure that the Mn element and the O element are uniformly distributed therein, but the density of dots is relatively low, indicating that MnO is distributed in both the precursor (S2) and the final product (S1), but the contents are not high.

Di, Ni₃S₂the/MnO composite (S1) and the unsintered precursor Material (S2) and the plating bath are Mn-free²⁺Prepared pure Ni₃S₂Comparative testing of the material (S3).

Respectively using the above cauliflower morphology Ni₃S₂the/MnO composite (S1) and the unsintered precursor Material (S2) and the plating bath are Mn-free²⁺Prepared pure Ni₃S₂Material (S3) was the working electrode and the electrochemistry was characterized using a three-electrode test systemCan be used. The material is directly plated on the current collector carbon paper, so that the step of preparing the working electrode is omitted. The three-electrode test system is assembled by taking a silver-silver chloride electrode as a reference electrode, a platinum mesh electrode as a counter electrode and 1M KOH aqueous solution as electrolyte. The cyclic voltammetry curve test of the battery is carried out on a Chenghua CHI760E electrochemical workstation, the charge and discharge test is carried out on a blue electricity Land CT-2001A test system, and the voltage interval is 0-0.6V (vs. Ag/AgCl). FIG. 4 shows Ni morphology of broccoli prepared in example 1₃S₂Cyclic voltammetry test, charge-discharge curve, rate capability and conversion ratio of/MnO composite material (S1) are respectively 2A g^-1Cycling performance plot at current density. As can be seen from the a diagram, the S1 material has a sharp reduction peak at 0.4V, the corresponding oxidation peak is located at 0.47V, and the polarization voltage between the two peaks is only 0.07V, which proves that the redox reaction has good reversibility. The graph b also shows a more stable electrochemical plateau at the corresponding potential. The reason for the smaller polarization is because the carbon paper as a current collector provides carbon fibers of large specific surface area for Ni₃S₂the/MnO adhesion, good conductivity and no binder obstruction also make the electron transfer efficiency between the current collector and the active mass higher. The C chart shows that the sample S1 has excellent cycling stability, 2A g^-1Initial specific capacity at that time was 87.3mAh g^-1After completing the charge-discharge cycle of 450 circles, the specific capacity is still kept at 85.1mAh g^-1The retention rate is as high as 97.5%. The coulombic efficiency was close to 100% throughout the process, which also indicates that the redox reaction is highly reversible. The cells were rate tested at different current densities, 4A g^-1、8A g^-1、 10A g^-1、15A g^-1The specific capacity of the material under the current density is 75mAh g respectively^-1、60mAh g^-1、50mAh g^-1And 30mAh g^-1(ii) a When the current returns to 2A g^-1Then, the specific capacity is recovered to 83mAh g^-1The material can still maintain the stability of the structure and the electrochemical performance under higher current density. FIG. 5 is a plot of cyclic voltammograms, charge and discharge curves, rate capability at 2A g for an unsintered precursor material (S2)^-1Cycling performance plot at current density. As can be seen from the cyclic voltammetry curve (a picture), a reduction peak is obviously smaller than an oxidation peak, and shows poor coulombic efficiency, and as can be seen from the cyclic test (c picture), the coulombic efficiency fluctuates from 60% to 100%, which is very unfavorable for the stability and safety of the battery. b it can be seen that the reduction potential of S2 is slightly decreased compared to S1, which also decreases the output voltage of the full cell, and also results in the loss of full cell power density and energy density. FIG. 6 shows that the plating bath does not contain Mn²⁺Prepared pure Ni₃S₂The cyclic voltammetry curve, charge-discharge curve and rate performance of the material (S3) are in a range of 2A g^-1Cycling performance plot at current density. The coulombic efficiency further declined than that of S2, and although the initial capacity was good, it was not well maintained, and the reduction potential was much lower, indicating that the content of MnO was very small but still able to cope with Ni₃S₂The electrochemical performance of the catalyst is greatly improved.

Example 2

Ni as described in example 1₃S₂The preparation method of the/MnO composite material is characterized in that:

NiCl in mixed solution₂In a concentration of 2.5mmol L^-1，MnCl₂In a concentration of 7.5mmol L^-1The concentration of thiourea was 0.5mol L^-1The electrodeposition time is 30min, the high-temperature calcination time is 1 hour, and Ni is obtained₃S₂The mass of active substance on the carbon paper is 1.5mg cm^-2。

The material is in a granular combined cauliflower shape and is densely coated on the surface of carbon fiber, and the XRD test respectively comprises carbon paper and Ni₃S₂And MnO with three different characteristic peaks, Mn element can be observed by element mapping.

Example 3

Ni as described in example 1₃S₂The preparation method of the/MnO composite material is characterized in that:

NiCl in mixed solution₂Has a concentration of 15mmol L^-1，MnCl₂Has a concentration of 10mmol L^-1The concentration of thiourea was 1mol L^-1The electrodeposition time is 120min, the high-temperature calcination time is 3 hours, and Ni is obtained₃S₂The mass of active substance on the carbon paper is 8mg cm^-2。

The material is in a granular combined cauliflower shape and is densely coated on the surface of carbon fiber, and the XRD test respectively comprises carbon paper and Ni₃S₂And MnO with three different characteristic peaks, Mn element can be observed by element mapping.

Example 4

Ni as described in example 1₃S₂The preparation method of the/MnO composite material is characterized in that:

NiCl in mixed solution₂In a concentration of 5mmol L^-1，MnCl₂In a concentration of 10mmol L^-1The concentration of thiourea was 0.5mol L^-1The electrodeposition time is 45min, the high-temperature calcination time is 1 h, and Ni is obtained₃S₂The mass of active substance on the carbon paper is 3mg cm^-2。

The material is in a granular combined cauliflower shape and is densely coated on the surface of carbon fiber, and the XRD test respectively comprises carbon paper and Ni₃S₂And MnO with three different characteristic peaks, Mn element can be observed by element mapping.

Example 5

Ni as described in example 1₃S₂The preparation method of the/MnO composite material is characterized in that:

NiCl in mixed solution₂In a concentration of 10mmol L^-1，MnCl₂In a concentration of 7.5mmol L^-1The concentration of thiourea was 0.5mol L^-1The electrodeposition time is 100min, the high-temperature calcination time is 2 hours, and Ni is obtained₃S₂The mass of active substance on the carbon paper is 6mg cm^-2。

The material is in a granular combined cauliflower shape and is densely coated on the surface of carbon fiber, and the XRD test respectively comprises carbon paper and Ni₃S₂And three different characteristic peaks of MnO, and element mapping can be observedTo Mn element.

Claims (10)

1. Ni₃S₂a/MnO composite of said Ni₃S₂the/MnO composite material is carbon paper loaded with Ni₃S₂Active material of MnO, Ni₃S₂The shape of the/MnO active substance is cauliflower-shaped, and the loading capacity of the active substance is 1.5-8 mgcm^-2。

2. Ni according to claim 1₃S₂the/MnO composite material is characterized in that the loading amount of the active substance is 4mgcm^-2。

3. Ni according to claim 1₃S₂The preparation method of the/MnO composite material comprises the following steps:

with NiCl₂、MnCl₂The mixed solution of thiourea and the electrolyte is used, active substances are electrodeposited on the surface of the carbon paper by an electrodeposition method, a precursor product is obtained after washing and drying, and then high-temperature calcination is carried out in an inert atmosphere to obtain Ni₃S₂a/MnO composite material.

4. Ni according to claim 3₃S₂The preparation method of the/MnO composite material is characterized in that NiCl in the mixed solution₂Has a concentration of 3 to 15mmol L^-1，MnCl₂The concentration of (A) is 2.5-10 mmol L^-1The concentration of thiourea is 0.25-1 mol L^-1。

5. Ni according to claim 3₃S₂The preparation method of the/MnO composite material is characterized in that the electrodeposition voltage is a constant voltage of-0.8V to-0.9V, the electrodeposition time is 30min to 120min, in the electrodeposition process, carbon paper is used as a working electrode, a platinum mesh electrode is used as a counter electrode, and a calomel electrode is used as a reference electrode.

6. Ni according to claim 5₃S₂A preparation method of a/MnO composite material,it is characterized in that the electro-deposition voltage is a constant voltage of-0.85V, and the electro-deposition time is 60 min.

7. Ni according to claim 3₃S₂The preparation method of the/MnO composite material is characterized in that the inert atmosphere is Ar gas, the high-temperature calcination temperature is 350-550 ℃, and the calcination time is 1-3 hours.

8. Ni according to claim 3₃S₂The preparation method of the/MnO composite material is characterized in that the diameter of the carbon fiber of the carbon paper is 7-9 mu m.

9. Ni₃S₂The preparation method of the/MnO composite material comprises the following steps:

with NiCl₂、MnCl₂Taking a mixed solution of thiourea and the electrolyte, electrodepositing the carbon paper at a constant potential of-0.85V to electrodeposit active substances on the surface of the carbon paper, washing and drying to obtain a precursor product, and calcining for 2 hours at 400 ℃ in an Ar atmosphere to obtain Ni₃S₂a/MnO composite material.

10. Ni according to claim 1₃S₂The application of the/MnO composite material is applied to aqueous alkaline batteries and used as a positive electrode material.

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