CN110676430A - Preparation method and application of porous metal electrode with bionic structure - Google Patents

Abstract

The invention discloses a preparation method and application of a porous metal electrode with a biomimetic structure. The preparation process is as follows: dissolving a transition metal salt in an ammonia solution to prepare a certain concentration of metal salt ammonia solution; soaking biomass fibers in the above-mentioned ammonia solution The metal salt ammonia solution is fully immersed and taken out, and then placed in an air or oxygen atmosphere for pre-calcination at 300-800 °C to obtain an oxide porous structure; the above-mentioned oxide porous structure is placed in a reducing atmosphere at 300-1000 °C for calcination Reductive heat treatment to obtain porous metal electrodes with biomimetic structures. The invention uses biomass fibers with biomimetic structure as templates, soaks and adsorbs metal salt raw materials, removes templates by calcination and reduction treatment, and can directly prepare three-dimensional porous metals or alloys with similar structures to biomass raw materials, and the preparation method is simple and convenient. The process cost is low, and it can be applied to lithium metal current collectors and catalytic electrodes for water electrolysis.

Description

A kind of preparation method and application of porous metal electrode with biomimetic structure

technical field

The invention belongs to the field of electrochemistry and biomimetic materials, and relates to a porous metal electrode, in particular to a preparation method and application of a porous metal electrode with a biomimetic structure.

Background technique

With the increasingly serious global problems such as environmental pollution and energy shortage, it is urgent to develop new energy and high-efficiency energy storage utilization technologies. The development of electrochemical energy conversion, electrochemical energy storage and utilization technology provides the possibility to realize efficient new energy conversion, utilization and storage. Electrochemical energy conversion and energy storage are inseparable from the preparation and structural design of electrode materials. Porous metal electrodes, such as nickel, copper and alloys, have a wide range of applications as electrode current collectors for lithium batteries, catalytic electrodes for hydrogen production from water electrolysis, etc.

Three-dimensional porous electrodes such as foamed copper and nickel foam are often used as current collectors for lithium metal, and are also often used to make catalytic electrodes for water electrolysis, and the catalytic performance is improved through the improvement of surface catalytic active sites. Such porous metals have disadvantages such as limited specific surface area and excessively large pore size.

SUMMARY OF THE INVENTION

One of the objectives of the present invention is to provide a preparation method of a porous metal electrode with a biomimetic structure, and to develop a porous metal electrode with a special porous structure and a high specific surface area.

The second purpose of the present invention is to provide the application of the porous metal electrode with biomimetic structure prepared by the above method.

In order to achieve the above purpose, the technical solution adopted in the present invention is as follows: a preparation method of a porous metal electrode with a bionic structure, comprising the following steps:

(1) the transition metal salt is dissolved in the aqueous ammonia solution, and is prepared into the aqueous ammonia solution of the metal salt of a certain concentration;

(2) soaking the biomass fiber in the above-mentioned metal salt ammonia solution, fully soaking it and taking it out, and then placing it in an air or oxygen atmosphere for pre-calcination at 300-800° C. for 1-180 min to obtain an oxide porous structure;

(3) The above-mentioned oxide porous structure is placed in a reducing atmosphere, and the temperature is raised to 300-1000° C. for reduction heat treatment for 1-180 minutes to obtain a porous metal electrode with a biomimetic structure.

Preferably, the transition metal salt is a mixture of one or more of nickel, copper and cobalt acetate, nitrate, oxalate and sulfate.

Preferably, the concentration of the metal salt ammonia solution is 0.5-5 mol/L.

Preferably, the biomass fiber is cotton fabric or wood. More preferably, the cotton fabric is a degreasing treated cotton fabric, and the wood is a lignin-removed wood.

The present invention also provides the application of the porous metal electrode with biomimetic structure prepared by the above method.

This kind of porous metal electrode has a special biomimetic porous structure and high specific surface area, which can provide a confined space for lithium metal, suppress the volume expansion during the deposition of lithium negative electrode, and control the growth of lithium metal in a three-dimensional porous structure, inhibiting confinement The growth of lithium dendrites can be used to prepare high-performance lithium metal current collectors.

Such porous metal electrodes also exhibit good electrocatalytic activities for hydrogen evolution and oxygen evolution, and can be used to prepare catalytic electrodes for water electrolysis.

Compared with the prior art, the present invention has the following beneficial effects:

1. The present invention uses biomass fibers with biomimetic structures as templates, soaks and adsorbs metal salt raw materials, removes templates by calcination and reduction treatment, and can directly prepare three-dimensional porous metals or alloys with similar structures to biomass raw materials. The structure has the characteristics of diverse structure, controllable structure, large specific surface area, and hierarchical pore structure.

2. The preparation method of the present invention is simple and convenient, and the process cost is low. The obtained porous metal electrode with biomimetic structure exhibits excellent performance when applied to current collectors of lithium metal and catalytic electrodes for water electrolysis.

3. The present invention uses cellulosic biomass as raw material, and has the advantages of easy availability of raw materials, controllable structure, low cost, large quantity, and little environmental pollution.

Description of drawings

FIG. 1 is a flow chart of synthesizing porous metal copper with a textile structure using cotton cloth as a template in Example 1 of the present invention.

FIG. 2 is an X-ray diffraction pattern (XRD) of copper oxide calcined in air and metallic copper reduced by hydrogen in Example 1 of the present invention.

3 is a scanning electron microscope image of cotton cloth raw material and porous copper synthesized by using cotton cloth as a template in Example 1 of the present invention.

Figure 4 shows nickel, cobalt, nickel-cobalt and nickel-copper alloys with textile structures synthesized by using cotton cloth as a template in Examples 2-5 of the present invention.

5 is a scanning electron microscope image of pine wood and porous copper with wood biomimetic structure synthesized by using pine wood as a template in Example 6 of the present invention.

6 is an electron microscope image of lithium metal deposited in a porous metal current collector with a cotton cloth biomimetic structure in Example 2 of the present invention and a lithium dendrite deposited on a copper plate as a comparison.

7 is the electrocatalytic hydrogen evolution and oxygen evolution performance of porous cobalt with cotton cloth biomimetic structure in Example 3 of the present invention.

Detailed ways

The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

The aqueous ammonia solution used in the following examples is industrial ammonia solution with a concentration of 20-28wt%.

Example 1

As shown in Figure 1, copper acetate hydrate was dissolved in an aqueous ammonia solution to prepare a solution containing 2 mol/L of copper ions.

Then put a piece of degreased cotton cloth into the solution, take out the cotton cloth after fully dipping, and heat the cotton to 300 degrees Celsius in an air atmosphere and keep it for 180min for pre-calcination.

The pre-calcined sample was heated to 300 degrees Celsius under a hydrogen atmosphere and held for 180 min, and then subjected to reduction treatment to obtain porous metal copper.

As shown in Figure 2, the metal copper salt is decomposed to form copper oxide after calcination in air, and the template is removed, and the copper oxide is reduced in hydrogen to obtain metal copper.

As shown in Fig. 3, the metallic copper product prepared by the cotton cloth template method maintains the morphology of the woven structure similar to that of the cotton cloth raw material.

Example 2

The nickel acetate hydrate was dissolved in an aqueous ammonia solution to prepare a solution containing 2.5 mol/L of nickel ions.

Then put a piece of degreased cotton cloth into the solution, take out the cotton cloth after fully impregnating it, and heat the cotton to 800 degrees Celsius in an air atmosphere and keep it for 60 minutes for pre-calcination.

The pre-calcined sample was heated to 1000 degrees Celsius and held for 60 min under a hydrogen atmosphere, and then subjected to reduction treatment to obtain porous metallic nickel.

Example 3

The cobalt acetate hydrate was dissolved in an aqueous ammonia solution to prepare a solution containing 5 mol/L of cobalt ions.

Then put a piece of degreased cotton cloth into the solution, take out the cotton cloth after fully dipping, and heat the cotton to 600 degrees Celsius in an air atmosphere and keep it for 60 minutes for pre-calcination.

The pre-calcined sample was heated to 600 degrees Celsius under a hydrogen atmosphere and held for 60 min, and then subjected to reduction treatment to obtain porous metal cobalt.

Example 4

Cobalt acetate hydrate and nickel acetate hydrate were dissolved in an aqueous ammonia solution in a molar ratio of 1:1 to prepare a solution containing 0.5 mol/L of metal ions.

Then put a piece of degreased cotton cloth into the solution, take out the cotton cloth after fully dipping, and heat the cotton to 600 degrees Celsius in an air atmosphere and keep it for 120 minutes for pre-calcination.

The pre-calcined sample was heated to 600 degrees Celsius under a hydrogen atmosphere and held for 120 min, and then subjected to reduction treatment to obtain a porous metal nickel-cobalt alloy.

Example 5

The copper acetate hydrate and the nickel acetate hydrate are dissolved in an aqueous ammonia solution in a molar ratio of 1:1 to prepare a solution containing 2.5 mol/L of metal ions.

Then put a piece of degreased cotton cloth into the solution, take out the cotton cloth after fully dipping, and heat the cotton to 600 degrees Celsius in an air atmosphere and keep it for 120 minutes for pre-calcination.

The pre-calcined sample was heated to 600 degrees Celsius under a hydrogen atmosphere and held for 120 min, and then subjected to reduction treatment to obtain a porous metal nickel-copper alloy.

As shown in Figure 4, the metal nickel, metal cobalt, nickel-cobalt alloy, and nickel-copper alloy products prepared by the cotton cloth template method can maintain the morphology of the woven structure similar to the cotton cloth raw material.

Example 6

The copper acetate was dissolved in an aqueous ammonia solution to prepare a solution containing 2.5 mol/L of copper ions.

Then, put a piece of pine wood treated by removing lignin into the solution, take out the wood after fully impregnating, and heat the wood to 600 degrees Celsius under an oxygen atmosphere and keep it for 30 minutes for pre-calcination.

The pre-calcined sample was heated to 600 degrees Celsius and held for 30 min in a hydrogen atmosphere, and then subjected to reduction treatment to obtain porous metal copper.

As shown in Figure 5, the metallic copper products prepared by the wood template method can maintain the porous morphology similar to that of the wood raw materials.

In order to further illustrate the application prospect of the porous metal electrode prepared by the present invention, porous metal nickel and porous metal cobalt are respectively selected as examples for electrochemical tests.

FIG. 6 corresponds to the porous metallic nickel with cotton cloth biomimetic structure prepared in Example 2. This product is used as a current collector for lithium metal. The specific test process is as follows: use lithium metal sheet as the counter electrode and reference electrode, use glass fiber as the diaphragm, use the metal current collector as the working electrode, dissolve in 1,3-dioxane and ethylene glycol dimethyl ether (DOX/DME, 1:1 v/v) mixed solvent and ₁ mol L ^-1 lithium bis-trifluoromethanesulfonimide (LiTFSI) with 1 wt% LiNO added as the electrolyte was assembled into a battery for Li metal in porous current collectors Electrodeposition experiments in . The traditional metal copper foil is used as a comparative experiment. FIG. 6 is a topography of the lithium metal deposited on the metal current collector when the current density of 1 mAcm ^-2 is controlled and the deposition amount of lithium metal is controlled to be 1 mAh cm ^-2 . It can be seen from Figure 6 that the morphology of the lithium metal deposited in the porous metal current collector with the cotton biomimetic structure is uniform, and no lithium dendrites are generated; while the lithium metal deposited on the copper foil shows a large number of dendrites. .

FIG. 7 corresponds to the porous metal cobalt with a cotton cloth biomimetic structure prepared in Example 3. The porous metal cobalt electrode is used for the catalytic hydrogen evolution and oxygen evolution electrode of water electrolysis. Figure 7 is the performance diagram of electrocatalytic hydrogen evolution and oxygen evolution when the scanning speed is 10mV s ^-1 in the KOH solution of 1 mol L ^-1 ; it can be seen from Figure 7 that the porous metal electrode shows good performance Activity for electrocatalytic hydrogen and oxygen evolution.

Claims (7)

1. A preparation method of a porous metal electrode with a bionic structure is characterized by comprising the following steps:

(1) dissolving transition metal salt in an ammonia water solution to prepare a metal salt ammonia water solution with a certain concentration;

(2) soaking biomass fibers into the metal salt ammonia water solution, taking out after full soaking, and then placing in air or oxygen atmosphere for precalcination at 800 ℃ for 1-180min at 300 ℃ to obtain an oxide porous structure;

(3) and (3) placing the oxide porous structure body in a reducing atmosphere, heating to 300-1000 ℃ for reduction heat treatment for 1-180min to obtain the porous metal electrode with the bionic structure.

2. The method for preparing a porous metal electrode with a biomimetic structure according to claim 1, wherein the transition metal salt is a mixture of one or more of nickel, copper, cobalt acetate, nitrate, oxalate, and sulfate.

3. The method for preparing the porous metal electrode with the bionic structure according to claim 1, wherein the concentration of the metal salt ammonia water solution is 0.5-5 mol/L.

4. The method for preparing a porous metal electrode with a bionic structure according to claim 1, wherein the biomass fiber is cotton fabric or wood.

5. The method for preparing a porous metal electrode with a biomimetic structure according to claim 4, wherein the cotton textile is a cotton textile subjected to degreasing treatment, and the wood is a wood subjected to lignin removal treatment.

6. Use of the porous metal electrode with biomimetic structure prepared by the preparation method according to any one of claims 1 to 5 in preparation of a current collector of lithium metal.

7. Use of the porous metal electrode with biomimetic structure prepared by the preparation method of any one of claims 1 to 5 in preparation of an electrolytic water catalytic electrode.

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