CN110931750A

CN110931750A - Copper-doped cobalt oxide porous nanosheet composite material and energy storage application

Info

Publication number: CN110931750A
Application number: CN201911239135.2A
Authority: CN
Inventors: 解勤兴; 谢东良
Original assignee: Tianjin Polytechnic University
Current assignee: Tianjin Polytechnic University
Priority date: 2019-12-06
Filing date: 2019-12-06
Publication date: 2020-03-27

Abstract

The invention discloses a preparation method of a copper-doped cobalt oxide porous nanosheet composite material, which comprises the following specific steps: dissolving cobalt salt and copper salt in a proper volume of water according to a cobalt/copper molar ratio of 0-5/1 to prepare a salt solution (0.01-1.0 mol/L), and dissolving dimethyl imidazole in the same volume of water to form a ligand solution (0.1-5.0 mol/L). The ligand solution and the salt solution are rapidly mixed and stirred uniformly. And (3) immersing the growth substrate into the mixed solution, and standing and reacting for 12-48 hours at room temperature. Taking out the matrix, sequentially cleaning with water and ethanol, and drying. And (3) heating the substrate to 350-800 ℃ at a heating rate of 1-5 ℃ per minute in an inert atmosphere, carrying out heat treatment for 1-6 hours, and cooling to room temperature to obtain the copper-doped cobalt oxide porous nanosheet composite material growing on the substrate. The composite material prepared by the method can be used as a lithium ion battery cathode material and a zinc ion battery anode material.

Description

Copper-doped cobalt oxide porous nanosheet composite material and energy storage application

Technical Field

The invention relates to the technical field of inorganic nonmetallic materials, in particular to a copper-doped cobalt oxide porous nanosheet composite material and a preparation method and an energy storage application thereof.

Background

As a novel energy storage device, the lithium ion battery is widely applied to the fields of information, national defense, aerospace, medical treatment, traffic and the like at present. With the increasing consumption of fossil energy and the facing problem of serious environmental pollution, the demand for new clean energy is increasing worldwide, and the research and development of lithium ion batteries with high energy density and long cycle life are promoted. High specific capacity energy storage Materials such as transition metal oxides, silicon carbon composites, etc. have been widely regarded (advanced energy Materials, 2017, 7: 1601424). However, it should be noted that although the metal oxide negative electrode material has a high theoretical specific capacity, the metal oxide has low conductivity, and a large volume expansion and contraction effect is caused by the deintercalation of lithium ions during the charging and discharging processes, so that the material is pulverized, dropped and inactivated, and the cycling stability is low.

In order to overcome the defects, most researches tend to prepare nano-structured metal oxide and compound the nano-structured metal oxide with carbon materials such as graphene, porous carbon, carbon nanotubes, carbon fibers and the like to prepare a composite negative electrode material, so that the conductivity of the nano-structured metal oxide can be improved on one hand, and the purpose of improving the cycle stability is achieved by using the carbon material as a matrix buffer volume effect on the other hand (Electrochimica Acta, 2016, 187: 508-516; Electrochimica Acta, 2015, 186: 50-57). Meanwhile, when the powder material is prepared into an electrode, a binder and a conductive agent such as acetylene black are required to be added, and excessive additives not only reduce the amount of active substances in the electrode to reduce the energy density of the battery, but also easily reduce the electron transfer rate and the ion diffusion efficiency of an electrolyte and influence the cycle stability.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention takes stainless steel mesh, copper foil, foamed nickel, carbon cloth, foamed copper and the like as growth substrates, a cobalt/copper metal organic frame grows on the surface of the growth substrates, a copper-doped cobalt oxide porous nanosheet composite material is prepared after heat treatment, the concentration of carriers in the cobalt oxide is improved through copper doping, and the purposes of improving the charge-discharge cycle stability and rate capability of the material are achieved.

The technical scheme adopted by the invention is as follows: dissolving cobalt salt and copper salt in a proper volume of water according to a cobalt/copper molar ratio of 0-5/1 to prepare a salt solution (0.01-1.0 mol/L), and dissolving dimethyl imidazole in the same volume of water to form a ligand solution (0.1-5.0 mol/L). The ligand solution and the salt solution are rapidly mixed and stirred uniformly. And (3) immersing the growth substrate into the mixed solution, and standing and reacting for 12-48 hours at room temperature. Taking out the matrix, sequentially cleaning with water and ethanol, and drying. And (3) heating the substrate to 350-800 ℃ at a heating rate of 1-5 ℃ per minute in an inert atmosphere, carrying out heat treatment for 1-6 hours, and cooling to room temperature to obtain the copper-doped cobalt oxide porous nanosheet composite material growing on the substrate.

The copper salt used in the above step is one or more of copper chloride, copper nitrate, copper acetate and copper sulfate.

The cobalt salt used in the above steps is one or more of cobalt chloride, cobalt sulfate, cobalt nitrate and cobalt acetate.

The substrate used in the above steps is one or more of stainless steel mesh, copper mesh, carbon cloth, copper foil, foam copper and foam nickel.

Drawings

FIG. 1 is a scanning electron micrograph of the product of example 1.

FIG. 2 is a scanning electron micrograph of the product of example 2.

FIG. 3 is a scanning electron micrograph of the product of example 3.

FIG. 4 is a scanning electron micrograph of the product of example 4.

FIG. 5 is an X-ray diffraction pattern of the products of examples 1, 3 and 4.

FIG. 6 is a graph of the charge and discharge cycle performance of the products of examples 1, 3 and 4.

Detailed Description

Example 1:

a salt solution was prepared by dissolving 1.5 mmol of cobalt nitrate in 30 ml of water and 12 mmol of dimethylimidazole in an equal volume of water to form a ligand solution. The ligand solution and the salt solution are rapidly mixed and stirred uniformly. The stainless steel mesh substrate was immersed in the mixed solution and allowed to stand still at room temperature for 24 hours. Taking out the matrix, sequentially cleaning with water and ethanol, and drying. And (3) heating the substrate to 450 ℃ at the heating rate of 2 ℃ per minute in an inert atmosphere, carrying out heat treatment for 2 hours, and cooling to room temperature to obtain the cobalt oxide porous nanosheet composite material growing on the substrate, wherein the morphology of the product is shown in fig. 1. Diffraction peaks of cobalt oxide and stainless steel mesh can be found in the product X-ray diffraction pattern, as shown in FIG. 5.

Example 2:

a salt solution was prepared by dissolving 1.5 mmol of cobalt nitrate in 30 ml of water and 12 mmol of dimethylimidazole in an equal volume of water to form a ligand solution. The ligand solution and the salt solution are rapidly mixed and stirred uniformly. The stainless steel mesh substrate was immersed in the mixed solution and allowed to stand still at room temperature for 24 hours. Taking out the matrix, sequentially cleaning with water and ethanol, and drying. And (3) heating the substrate to 350 ℃ at the heating rate of 2 ℃ per minute in an inert atmosphere, carrying out heat treatment for 2 hours, and cooling to room temperature to obtain the cobalt oxide porous nanosheet composite material growing on the substrate, wherein the morphology of the product is shown in fig. 2.

Example 3:

a salt solution was prepared by dissolving 1.125 mmol of cobalt nitrate and 0.375 mmol of copper nitrate in 30 ml of water, and 12 mmol of dimethylimidazole in an equal volume of water to form a ligand solution. The ligand solution and the salt solution are rapidly mixed and stirred uniformly. The stainless steel mesh substrate was immersed in the mixed solution and allowed to stand still at room temperature for 24 hours. Taking out the matrix, sequentially cleaning with water and ethanol, and drying. And (3) heating the substrate to 450 ℃ at the heating rate of 2 ℃ per minute in an inert atmosphere, carrying out heat treatment for 2 hours, and cooling to room temperature to obtain the copper-doped cobalt oxide porous nanosheet composite material growing on the substrate, wherein the morphology of the product is shown in fig. 1. The morphology of the product is shown in FIG. 3. Diffraction peaks of the copper-doped cobalt oxide and the stainless steel mesh can be found in the X-ray diffraction pattern of the product, as shown in FIG. 5. The copper-doped cobalt oxide diffraction peak position is significantly shifted to a lower angle than the XRD diffraction peak of cobalt oxide in the product of example 1, indicating that copper atoms were successfully doped into the cobalt oxide lattice.

Example 4:

a salt solution was prepared by dissolving 0.75 mmol of cobalt nitrate and 0.75 mmol of copper nitrate in 30 ml of water, and dimethylimidazole was dissolved in an equal volume of water to form a ligand solution. The ligand solution and the salt solution are rapidly mixed and stirred uniformly. The stainless steel mesh substrate was immersed in the mixed solution and allowed to stand still at room temperature for 24 hours. Taking out the matrix, sequentially cleaning with water and ethanol, and drying. And (3) heating the substrate to 450 ℃ at the heating rate of 2 ℃ per minute in an inert atmosphere, carrying out heat treatment for 2 hours, and cooling to room temperature to obtain the copper-doped cobalt oxide porous nanosheet composite material growing on the substrate, wherein the morphology of the product is shown in fig. 1. The morphology of the product is shown in FIG. 4. The diffraction peaks of the copper-doped cobalt oxide and the stainless steel mesh can be found in the product X-ray powder diffraction pattern, as shown in FIG. 5. The copper-doped cobalt oxide diffraction peak position is significantly shifted to a lower angle than the XRD diffraction peak of cobalt oxide in the product of example 1, indicating that copper atoms were successfully doped into the cobalt oxide lattice.

Example 5: electrochemical performance testing of materials

Electrochemical properties of the materials were tested at room temperature using a button cell system with 1.0M LiPF electrolyte₆EC + DEC (volume ratio 1: 1). A blue CT2001A type battery test system is adopted to carry out charge and discharge tests, and the voltage range is 0.01-3V. The result is shown in fig. 6, the carbon nanosheet embedded copper-doped cobalt oxide composite material has high specific discharge capacity, high first charge-discharge coulombic efficiency and good cycle stability.

Claims

1. A preparation method of a copper-doped cobalt oxide porous nanosheet composite material comprises the following specific steps: dissolving cobalt salt and copper salt in a proper volume of water according to a cobalt/copper molar ratio of 0-5/1 to prepare a salt solution (0.01-1.0 mol/L), and dissolving dimethyl imidazole in the same volume of water to form a ligand solution (0.1-5.0 mol/L). The ligand solution and the salt solution are rapidly mixed and stirred uniformly. And (3) immersing the growth substrate into the mixed solution, and standing and reacting for 12-48 hours at room temperature. Taking out the matrix, sequentially cleaning with water and ethanol, and drying. And (3) heating the substrate to 350-800 ℃ at a heating rate of 1-5 ℃ per minute in an inert atmosphere, carrying out heat treatment for 1-6 hours, and cooling to room temperature to obtain the doped cobalt oxide porous nanosheet composite material growing on the substrate.

2. The preparation method of the copper-doped cobalt oxide porous nanosheet composite material according to claim 1, wherein the cobalt salt is one or more of cobalt chloride, cobalt sulfate, cobalt nitrate and cobalt acetate.

3. The preparation method of the copper-doped cobalt oxide porous nanosheet composite material of claim 1, wherein the copper salt is one or more of copper chloride, copper nitrate, copper acetate and copper sulfate.

4. The preparation method of the copper-doped cobalt oxide porous nanosheet composite material according to claim 1, wherein the substrate is one or more of a stainless steel mesh, a copper mesh, carbon cloth, copper foil, copper foam and nickel foam.

5. A copper doped cobalt oxide porous nanoplate composite prepared by the method of any one of claims 1 to 4.

6. The copper-doped cobalt oxide porous nanosheet composite of claim 5 being useful as a lithium ion battery negative electrode material.

7. The copper-doped cobalt oxide porous nanosheet composite of claim 5 being useful as a zinc ion battery positive electrode material.