CN113299930B

CN113299930B - Air electrode containing bismuth oxide catalyst and preparation method thereof

Info

Publication number: CN113299930B
Application number: CN202110468797.8A
Authority: CN
Inventors: 姜雄亮; 钟澄; 宋永江; 栗佳
Original assignee: Hunan Yuanda New Material Co ltd
Current assignee: Hunan Yuanda New Material Co ltd
Priority date: 2021-04-28
Filing date: 2021-04-28
Publication date: 2022-11-01
Anticipated expiration: 2041-04-28
Also published as: CN113299930A

Abstract

The invention discloses an air electrode containing a bismuth oxide catalyst and a preparation method thereof; the catalyst is bismuth oxide; the bismuth oxide is selected from alpha-Bi₂O₃、β‑Bi₂O₃. During preparation, mixing bismuth oxide powder, a conductive agent, a binder and an adsorbent, adding an organic solvent, and preparing into a paste; rolling the paste to prepare a catalytic film, or coating the paste on a current collector or a waterproof breathable film to form the catalytic film; and attaching catalytic films on two sides of the positive current collector, and attaching a waterproof breathable film on the outer side of the catalytic film on one side to prepare the air electrode. The air electrode of the invention adopts bismuth oxide to replace manganese dioxide as a catalyst, thus reducing the cost and improving the discharge voltage.

Description

Air electrode containing bismuth oxide catalyst and preparation method thereof

Technical Field

The invention belongs to the technical field of air batteries, relates to an air electrode, and particularly relates to an air electrode containing a bismuth oxide catalyst and a preparation method thereof.

Background

Since the positive electrode active material of the air electrode is oxygen in the air, and the electrochemical reaction of the battery occurs at the solid-liquid-gas three-phase interface formed by the air battery and the electrolyte, the electrochemical reaction speed is controlled by the diffusion speed of oxygen from the air and the reaction activity at the interface. Therefore, to increase the discharge current density of the fresh air battery, two considerations may be considered: firstly, the air diffusion capacity of the air electrode is improved, namely the air permeability is improved; and secondly, the electrochemical reaction activity of a solid-liquid-gas three-phase interface is improved. The improvement of the electrochemical reaction activity of the solid-liquid-gas three-phase interface is generally realized by selecting a catalytic material with excellent catalytic performance.

The electrode catalyst for an air electrode needs to satisfy: (1) has certain electronic conductivity; at least an electron channel is provided which, after being sufficiently mixed with the conductive material, can provide for electron exchange without causing a significant voltage drop; (2) The catalyst has good electrocatalytic activity on reduction and precipitation of oxygen; but also has good catalytic decomposition effect on hydrogen peroxide; (3) The electrochemical stability in alkaline electrolyte is good, and the service life is long; and (4) the price is low, and the resources are rich.

Disclosure of Invention

The invention aims to provide a novel air electrode containing a bismuth oxide catalyst and a preparation method thereof.

The purpose of the invention is realized by the following technical scheme:

in a first aspect, the present invention relates to an air electrode catalyst, said catalyst being bismuth oxide; the bismuth oxide is selected from alpha-Bi₂O₃、β-Bi₂O₃。

In a second aspect, the present invention relates to an air electrode comprising a catalyst, a binder, an adsorbent and a conductive agent, wherein the catalyst is bismuth oxide; the bismuth oxide is selected from alpha-Bi₂O₃、β-Bi₂O₃。

As an embodiment of the present invention, the α -Bi₂O₃Has an average particle diameter of 0.5 to 10 μm.

As an embodiment of the present invention, the beta-Bi₂O₃Has an average particle diameter of 2 to 50 μm.

As an embodiment of the invention, the binder is one or more of polytetrafluoroethylene, low-pressure polyethylene, polyvinylidene fluoride and polyvinyl alcohol.

As an embodiment of the present invention, the conductive agent is one or more of conductive carbon black, graphene, carbon nanotubes, carbon fibers, metal powder, and conductive polymer.

As an embodiment of the present invention, the adsorbent is activated carbon; or a mixture of activated carbon and activated alumina powder, wherein the activated alumina powder is present in an amount of 1 to 10% by weight of the total mixture.

As an embodiment of the present invention, the catalytic slurry of the air electrode is composed of a catalytic material and an organic solvent in a mass ratio of 0.825; the catalytic material contains 5-40 parts of bismuth oxide, 5-30 parts of a conductive agent, 10-30 parts of a binder and 20-50 parts of an adsorbent.

In a third aspect, the present invention relates to a method for preparing the air electrode, the method comprising the steps of:

s1, preparing a catalytic membrane: mixing bismuth oxide powder, a conductive agent, a binder and an adsorbent, adding an organic solvent, and preparing into a paste; rolling the paste to prepare a catalytic film, or coating the paste on a current collector or a waterproof breathable film to form the catalytic film;

and S2, attaching catalytic films on two sides of the positive current collector, and attaching a waterproof breathable film on the outer side of the catalytic film on one side to prepare the air electrode.

In a fourth aspect, the present invention relates to a metal-air battery, an air electrode of which is the air electrode according to claim 2.

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

1) The inventors have found that bismuth oxide has the oxidizing and reducing properties of oxygen under the system (alkaline liquid) conditions of the present invention; further, it has been found that bismuth oxide has a higher discharge voltage instead of manganese dioxide as a catalyst, and a novel catalyst for air electrodes is provided.

2) The air electrode of the invention adopts bismuth oxide as a catalyst, which can reduce the cost and improve the discharge voltage.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:

FIG. 1 shows α -Bi₂O₃A schematic diagram of particle size distribution; wherein, 1 is the particle size, and 2 is the content;

FIG. 2 shows beta-Bi₂O₃A schematic diagram of the particle size distribution; wherein, 1 is the particle size, and 2 is the content;

fig. 3 is a comparative graph showing performance tests of the air batteries of example 2 and comparative examples 1 to 5.

Detailed Description

The present invention will be described in detail with reference to examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be apparent to those skilled in the art that several modifications and improvements can be made without departing from the inventive concept. All falling within the scope of the invention.

Examples 1 to 3

Examples 1 to 3 provide an air electrode, an aluminum-air battery, and their preparation; the method comprises the following steps:

(1) Preparation of catalytic Material

The air electrode uses bismuth oxide as a catalyst. Wherein the crystal form of bismuth oxide is alpha-Bi₂O₃(yellowish) and beta-Bi₂O₃All of (orange yellow), wherein, alpha-Bi₂O₃The particle size distribution is shown in figure 1, beta-Bi₂O₃The particle size distribution is shown in figure 2.

Examples 1 to 3 use beta-Bi₂O₃. The specific components and the use amount are shown in the following table:

wherein, the binder adopts PTFE with solid content of 60%. The components and amounts of the air electrodes of comparative examples 1 to 5 used for comparison were as shown in the table above, and the other steps were the same as in the examples.

Actual ingredient table: (then wet dispersed with ethanol, stirred) the actual composition of the batch produced changed because PTFE only had a 60% solids fraction.

Practical ingredient tables for examples 1-3

	Catalyst (%)	Activated carbon (%)	Conductive carbon Black (%)	60% PTFE emulsion (%)	Carbon nanotubes (%)
						Example 1	15	33	20	32	0
Example 2	19.6	35	15	30	0
						Example 3	20	24	29	24	3

Practical ingredient tables for comparative examples 1 to 5

	Nano manganese dioxide (%)	Catalyst (%)	Activated charcoal (%)	Conductive carbon Black (%)	60% PTFE emulsion (%)
						1		19.6	35	15	30
2	14.7	4.9	35	15	30
						3	9.8	9.8	35	15	30
4	4.9	14.7	35	15	30
						5	16	16	29	13	26

(2) The preparation method of the catalytic membrane comprises the following steps:

mixing the components, adding an organic solvent (ethanol, and the mass ratio of the mixed components to the ethanol is 0.825. The catalyst can also be coated on a current collector or a waterproof breathable film to form a catalytic film.

(3) Testing the performance of the air battery:

attaching catalytic films on two sides of the positive current collector, attaching a waterproof breathable film on the outer side of one side of the catalytic film, and making into air electrode, wherein the anode is aluminum plate, the electrolyte is 6M potassium hydroxide at a concentration of 50mA/cm²Constant current discharge is carried out, and voltage is adopted once per second. The effect is shown in fig. 3, wherein M20 is nano manganese dioxide 22%, B20 is bismuth oxide 22%, and M15+ B5 is manganese dioxide 16% + bismuth oxide 6%. The nano manganese oxide has particle size of 50nm99.9%,32m2/g, and is alpha (amorphous) manganese dioxide. Fig. 3 is a comparison of performance tests of the air cells of example 2 and comparative examples 1-5.

The foregoing description has described specific embodiments of the present invention. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes and modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention.

Claims

1. An air electrode comprises a catalyst, a binder, an adsorbent and a conductive agent, and is characterized in that the catalyst is bismuth oxide; the bismuth oxide is selected from alpha-Bi₂O₃、β-Bi₂O₃(ii) a The catalytic slurry of the air electrode consists of a catalytic material and an organic solvent in a mass ratio of 0.825; the catalytic material contains 5-40 parts of bismuth oxide, 5-30 parts of a conductive agent, 10-30 parts of a binder and 20-50 parts of an adsorbent; the conductive agent is one or more of conductive carbon black, graphene, carbon nanotubes and carbon fibers; the organic solvent is ethanol;

the air electrode is prepared by the following steps:

and S2, attaching catalytic membranes on two sides of the positive current collector, and attaching a waterproof breathable film on the outer side of the catalytic membrane on one side to form the air electrode.

2. The air electrode of claim 1, wherein the α -Bi is₂O₃The particle diameter of (A) is 0.5 to 10 μm.

3. The air electrode of claim 1, wherein the β -Bi is₂O₃The particle diameter of (A) is 2 to 50 μm.

4. The air electrode of claim 1, wherein the binder is one or more of polytetrafluoroethylene, low pressure polyethylene, polyvinylidene fluoride, and polyvinyl alcohol.

5. The air electrode of claim 1, wherein the adsorbent is activated carbon; or a mixture of activated carbon and activated alumina powder, wherein the activated alumina powder is present in an amount of 1 to 10% by weight of the total mixture.

6. A metal-air battery, characterized in that the air electrode of the battery is the air electrode of claim 1.