AIR ELECTRODE, PREPARATION METHOD AND APPLICATION THEREOF

Abstract

Air electrode, preparation method and application thereof are disclosed. The air electrode includes a first diffusion layer, a current collecting layer disposed on the first diffusion layer, a second diffusion layer disposed on the current collecting layer and a catalyst layer including catalytic active component, where the catalytic active component includes silicon powder.

Claims

1. An air electrode for an electrochemical device, the air electrode comprising: a first diffusion layer; a current collecting layer disposed on the first diffusion layer; a second diffusion layer disposed on the current collecting layer, and a catalyst layer disposed on the second diffusion layer, the catalyst layer comprising a catalytic active component, wherein the catalytic active component comprises silicon powder for catalyzing electrochemical reduction of oxygen adsorbed on the silicon powder.

2. The air electrode of claim 1, wherein in the catalyst layer, the silicon powder has a mass percentage between 5% and 55%.

3. The air electrode of claim 1, wherein the silicon powder has a particle size between 1 ?m and 100 ?m.

4. The air electrode of claim 3, wherein the silicon powder has a median particle diameter D50 of 21 ?m.

5. The air electrode of claim 1, wherein in the catalyst layer, the catalytic active component comprises aluminum oxide.

6. The air electrode of claim 5, wherein the aluminum oxide comprises ?-Al.sub.2O.sub.3.

7. The air electrode of claim 1, wherein the catalyst layer further comprises a conductive agent, activate carbon, and a binder.

8. (canceled)

9. The air electrode of claim 7, wherein the conductive agent comprises at least one of carbon black, conductive graphite, carbon fiber, carbon nanotube, graphene and metal powder.

10. The air electrode of claim 7, wherein the binder comprises at least one of polytetrafluoroethylene emulsion, polyethylene wax emulsion, polyvinylidene fluoride emulsion, silicone-acrylic emulsion and silicone emulsion.

11. (canceled)

12. A method for preparing an air electrode for an electrochemical device, the method comprising: roll-processing a mixture of carbon black, activate carbon, a polytetrafluoroethylene emulsion, and ethanol to respectively obtain a first diffusion layer and a second diffusion layer; obtaining a current collecting layer; obtaining a catalyst layer by roll-processing a composition comprising silicon powder, wherein the silicon powder is a catalytic active substance for catalyzing electrochemical reduction of oxygen, stacking sequentially the first diffusion layer, the current collecting layer, the second diffusion layer, and the catalyst layer to obtain a multilayer body; and roll-pressing the multilayer body to form the air electrode.

13-14. (canceled)

15. A refrigerator comprising: a closed space for preserving food; and an air electrode for de-oxygenation in the closed space, the air electrode placed in the closed space and comprising: a first diffusion layer, the first diffusion layer comprising carbon black, active carbon, and polytetrafluorethylene; a current collecting layer disposed on the first diffusion layer; a second diffusion layer disposed on the current collecting layer, the second diffusion layer comprising carbon black, activate carbon, and polytetrafluorethylene; and a catalyst layer disposed on the second diffusion layer, the catalyst layer comprising a catalytic active component, wherein the catalytic active component comprises silicon powder for catalyzing electrochemical reduction of oxygen absorbed on the silicon powder.

16. The air electrode of claim 1, wherein the silicon powder has a silicon content of at least 99% by weight in a form of elemental silicon.

17. The air electrode of claim 1, wherein the catalyst layer is free from platinum, gold, palladium, ruthenium oxide, iridium, manganese oxide, cobalt oxide, and manganese-cobalt composite oxide.

18. The air electrode of claim 1, wherein the oxygen is not reduced to hydrogen peroxide nor hydrogen peroxide ion in the electrochemical reduction catalyzed by the silicon powder.

19. The air electrode of claim 1, wherein each of the first diffusion layer and the second diffusion layer comprises carbon black, activate carbon, and polytetrafluoroethylene

20. The method of claim 12, wherein the silicon powder has a silicon content of at least 99% by weight in a form of elemental silicon.

21. The method of claim 12, wherein the composition further comprises aluminum oxide.

22. The method of claim 12, wherein the composition further comprises a conductive agent, activate carbon, and a binder.

23. The method of claim 22, wherein the conductive agent comprises at least one of carbon black, conductive graphite, carbon fiber, carbon nanotube, graphene and metal powder.

24. The method of claim 22, wherein the binder comprises at least one of polytetrafluoroethylene emulsion, polyethylene wax emulsion, polyvinylidene fluoride emulsion, silicone-acrylic emulsion and silicone emulsion.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0102] FIG. 1 is a schematic diagram of the preparation method of an air electrode according to an embodiment of the present disclosure.

[0103] FIG. 2 is a schematic structural diagram of an air electrode according to an embodiment of the present disclosure.

[0104] FIG. 3 is a schematic diagram of a test device for the air electrode according to an embodiment of the present disclosure.

REFERENCE NUMERALS

[0105] 100: First diffusion layer; [0106] 101: Current collecting layer; [0107] 102: Second diffusion layer; [0108] 103: Catalyst layer; [0109] 200: Power; [0110] 201: Air electrode; [0111] 202: Anode; [0112] 203: Electrolyte.

DETAILED DESCRIPTION OF THE DISCLOSURE

[0113] The concept and technical effects of the present disclosure will be described in detail hereinafter with reference to exemplary implementations, for the convenience of understanding the purpose, features and effects of the present disclosure. Apparently, the described implementations are only part but not all of the embodiments of the present disclosure. Based on the described implementations of the present disclosure, any other implementations obtained by those skilled in the art without creative labor are all within the scope of protection of the present disclosure.

[0114] In the description of the present disclosure, the terms first, second, third, etc. are described only for the purpose of distinguishing technical features, and shall not be understood as indicating or implying relative importance, implicitly indicating the number or the order of the indicated technical features.

[0115] In the description of the present disclosure, it shall be understood that the orientation or positional relationship related to the orientation description, such as the orientation or position relation indicated by up, down, left, right, etc., is based on the orientation or positional relation shown in the drawings, which is only for the convenience of description of the present disclosure and for the simplification of the description, instead of indicating or implying that the indicated device or element must have a specific orientation, or be constructed and operated in a specific orientation, and thus shall not be understood as a limitation of the present disclosure.

[0116] In the description of the present disclosure, it should be noted that unless otherwise clearly defined, words such as configured, arranged, connected, etc., shall be understood broadly, and those skilled in the art can reasonably determine the specific meanings of the above words in the present disclosure in combination with the specific contents of the technical schemes.

Embodiment 1

[0117] In this embodiment an air electrode is prepared, and the preparation process is shown in FIG. 1, which includes the following steps:

[0118] S1: preparing a first diffusion layer. S1 includes the following steps: [0119] mixing 15 parts (by weight) of carbon black, 40 parts of activate carbon and 45 parts of PTFE emulsion to obtain a mixture; [0120] adding ethanol to the mixture, and roll-processing for several times to prepare the first diffusion layer.

[0121] S2: preparing a current collecting layer. S2 includes the following steps: [0122] degreasing: soaking current collecting layer metal in acetone at 25? C. for 10 min; [0123] rinsing: rinsing the degreased current collecting layer metal with water for three times; [0124] acid rinsing: rinsing the rinsed current collecting layer metal with 5 mol/L hydrochloric acid aqueous solution for 10 min under ultrasonic, and rinsing with ethanol and water for 4 times; [0125] drying: drying the current collecting layer metal after acid rinsing at 60? ? C. for 5 h (hour).

[0126] S3: preparing a second diffusion layer. S3 includes the following steps: [0127] mixing 15 parts (by weight) of carbon black, 40 parts of activate carbon and 45 parts of PTFE emulsion to obtain a mixture; [0128] adding ethanol to the mixture, and roll-processing for several times to prepare the second diffusion layer.

[0129] S4: preparing a catalyst layer: mixing the following components in percentage by mass: silicon powder: 20%, carbon black: 12%, activate carbon: 35% and PTFE emulsion binder: 33% under high-speed stirring to obtain a mixture, and then roll-processing the mixture for several times.

[0130] S5: preparing the air electrode: stacking sequentially the first diffusion layer 100, the current collecting layer 101, the second diffusion layer 102 and the catalyst layer 103 according to the structure shown in FIG. 2 to obtain a multilayer body, and then roll-processing the multilayer body to form the air electrode.

[0131] The silicon powder used in this embodiment was purchased from Qinghe Chuangying Metal Material Co., Ltd., in which the silicon content was 99.96 wt %, and the impurities included 0.03 wt % iron, 0.014 wt % copper, 0.005 wt % tin, etc., with the median particle diameter D50 of silicon powder of about 21 ?m.

Embodiment 2

[0132] In this embodiment an air electrode is prepared, and the preparation process is shown in FIG. 1, which includes the following steps:

[0133] S1: preparing a first diffusion layer. S1 includes the following steps: [0134] mixing 15 parts (by weight) of carbon black, 40 parts of activate carbon and 45 parts of PTFE emulsion to obtain a mixture; [0135] adding ethanol to the mixture, and roll-processing for several times to prepare the first diffusion layer.

[0136] S2: preparing a current collecting layer. S2 includes the following steps: [0137] degreasing: soaking current collecting layer metal in acetone at 25? C. for 10 min; [0138] rinsing: rinsing the degreased current collecting layer metal with water for three times; [0139] acid rinsing: rinsing the rinsed current collecting layer metal with 5 mol/L hydrochloric acid aqueous solution for 10 min under ultrasonic, and rinsing with ethanol and water for 4 times; [0140] drying: drying the current collecting layer metal after acid rinsing at 60? C. for 5 h.

[0141] S3: preparing a second diffusion layer. S3 includes the following steps: [0142] mixing 15 parts (by weight) of carbon black, 40 parts of activate carbon and 45 parts of PTFE emulsion to obtain a mixture; [0143] adding ethanol to the mixture, and roll-processing for several times to prepare the second diffusion layer.

[0144] S4: preparing a catalyst layer: mixing the following components in percentage by mass: silicon powder: 30%, carbon black: 10%, activate carbon: 27% and PTFE emulsion binder: 33% under high-speed stirring to obtain a mixture, and then roll-processing the mixture for several times.

[0145] S5: preparing the air electrode: stacking sequentially the first diffusion layer 100, the current collecting layer 101, the second diffusion layer 102 and the catalyst layer 103 according to the structure shown in FIG. 2 to obtain a multilayer body, and then roll-processing the multilayer body to form the air electrode.

[0146] The silicon powder used in this embodiment was purchased from Qinghe Chuangying Metal Material Co., Ltd., in which the silicon content was 99.96 wt %, and the impurities included 0.03 wt % iron, 0.014 wt % copper, 0.005 wt % tin, etc., with the median particle diameter D50 of silicon powder of about 21 ?m.

Embodiment 3

[0147] In this embodiment an air electrode is prepared, and the preparation process is shown in FIG. 1, which includes the following steps:

[0148] S1: preparing a first diffusion layer. S1 includes the following steps: [0149] mixing 15 parts (by weight) of carbon black, 40 parts of activate carbon and 45 parts of PTFE emulsion to obtain a mixture; [0150] adding ethanol to the mixture, and roll-processing for several times to prepare the first diffusion layer.

[0151] S2: preparing a current collecting layer. S2 includes the following steps: [0152] degreasing: soaking current collecting layer metal in acetone at 25? C. for 10 min; [0153] rinsing: rinsing the degreased current collecting layer metal with water for three times; [0154] acid rinsing: rinsing the rinsed current collecting layer metal with 5 mol/L hydrochloric acid aqueous solution for 10 min under ultrasonic, and rinsing with ethanol and water for 4 times; [0155] drying: drying the current collecting layer metal after acid rinsing at 60? C. for 5 h.

[0156] S3: preparing a second diffusion layer. S3 includes the following steps: [0157] mixing 15 parts (by weight) of carbon black, 40 parts of activate carbon and 45 parts of PTFE emulsion to obtain a mixture; [0158] adding ethanol to the mixture, and roll-processing for several times to prepare the second diffusion layer.

[0159] S4: preparing a catalyst layer: mixing the following components in percentage by mass: silicon powder: 35%, carbon black: 10%, activate carbon: 22% and PTFE emulsion binder: 33% under high-speed stirring to obtain a mixture, and then roll-processing the mixture for several times.

[0160] S5: preparing the air electrode: stacking sequentially the first diffusion layer 100, the current collecting layer 101, the second diffusion layer 102 and the catalyst layer 103 according to the structure shown in FIG. 2 to obtain a multilayer body, and then roll-processing the multilayer body to form the air electrode.

[0161] The silicon powder used in this embodiment was purchased from Qinghe Chuangying Metal Material Co., Ltd., in which the silicon content was 99.96 wt %, and the impurities included 0.03 wt % iron, 0.014 wt % copper, 0.005 wt % tin, etc., with the median particle diameter D50 of silicon powder of about 21 ?m.

Embodiment 4

[0162] In this embodiment an air electrode is prepared, and the preparation process is shown in FIG. 1, which includes the following steps:

[0163] S1: preparing a first diffusion layer. S1 includes the following steps: [0164] mixing 15 parts (by weight) of carbon black, 40 parts of activate carbon and 45 parts of PTFE emulsion to obtain a mixture; [0165] adding ethanol to the mixture, and roll-processing for several times to prepare the first diffusion layer.

[0166] S2: preparing a current collecting layer. S2 includes the following steps: [0167] degreasing: soaking current collecting layer metal in acetone at 25? C. for 10 min; [0168] rinsing: rinsing the degreased current collecting layer metal with water for three times; [0169] acid rinsing: rinsing the rinsed current collecting layer metal with 5 mol/L hydrochloric acid aqueous solution for 10 min under ultrasonic, and rinsing with ethanol and water for 4 times; [0170] drying: drying the current collecting layer metal after acid rinsing at 60? C. for 5 h.

[0171] S3: preparing a second diffusion layer. S3 includes the following steps: [0172] mixing 15 parts (by weight) of carbon black, 40 parts of activate carbon and 45 parts of PTFE emulsion to obtain a mixture; [0173] adding ethanol to the mixture, and roll-processing for several times to prepare the second diffusion layer.

[0174] S4: preparing a catalyst layer: mixing the following components in percentage by mass: silicon powder: 20%, ?-Al.sub.2O.sub.3: 2%, carbon black: 12%, activate carbon: 33% and PTFE emulsion binder: 33% under high-speed stirring to obtain a mixture, and then roll-processing the mixture for several times.

[0175] S5: preparing the air electrode: stacking sequentially the first diffusion layer 100, the current collecting layer 101, the second diffusion layer 102 and the catalyst layer 103 according to the structure shown in FIG. 2 to obtain a multilayer body, and then roll-processing the multilayer body to form the air electrode.

[0176] In this embodiment, the catalytic active component in the catalyst layer is the silicon powder combined with ?-Al.sub.2O.sub.3, and the combination of the two is beneficial to further improve the catalytic activity and reduce the charging voltage.

Embodiment 5

[0177] In this embodiment, a refrigerating device including the air electrode is provided.

[0178] As the air electrode can remove oxygen, when the air electrode is arranged in the refrigeration device and when the refrigerator door is closed, the air electrode starts to work to remove the oxygen inside the refrigeration device, thus inhibiting the respiration of fruits and vegetables as well as promoting the preservation.

[0179] It can be understood that the refrigeration device referred to in the present disclosure may include commercial freezer, cold storage, cold chain vehicles and other equipment besides household refrigerator.

[0180] In modern logistics, cold chain transportation is getting more and more important. Cold chain transportation refers to the transportation in which the transported goods always keep a certain temperature in the whole transportation process, whenever loading and unloading the goods, changing the transportation mode, changing the packaging equipment, etc.

[0181] The cold chain transportation mode can be road transportation, waterway transportation, railway transportation, air transportation, or a comprehensive transportation mode composed of various transportation modes. Cold chain transportation is an important link of cold chain logistics. Cold chain transportation takes high cost, and includes complex mobile refrigeration technology and incubator manufacturing technology. The management of cold chain transportation involves high risks and uncertainties.

[0182] The objects of cold chain transportation can mainly be divided into fresh products, processed foods and pharmaceutical products. Among them, fresh products include vegetables and fruits, meat, poultry, eggs, aquatic products and flower products. Processed foods include quick-frozen food, packaged cooked food such as poultry, meat and aquatic product, ice cream, dairy products and fast food raw materials. Pharmaceutical products include all kinds of medicines that need refrigeration, such as vaccines and medical devices.

[0183] Some foods may be discarded during transportation due to the inability to keep fresh for a long time. During transportation, most of the fresh, living and perishable goods can't be preserved for a long time because of decay, except that a few of them die or can't be preserved due to improper care on the way or discomfort to vehicles. For animal food, the cause of decay is mainly the action of microorganisms. For plant food, the cause of decay is mainly caused by respiration.

[0184] The cold chain transportation must be carried out by special vehicles such as freezing or refrigeration vehicles, which must be equipped with freezing or refrigeration and heat preservation equipment, besides the same car body and machinery as a freight car. In the process of transportation, special attention should be paid to continuous refrigeration, because microbial activities and respiration are strengthened with the increase of temperature. If the conditions of continuous refrigeration cannot be guaranteed in each link of transportation, then the goods may begin to rot and deteriorate in a certain link.

[0185] It can be understood that when the air electrode of the present disclosure is used in a link of the cold chain transportation, it would be beneficial for inhibition of the reproduction of microorganisms and the respiration by the de-oxygenation effect of the air electrode, so as to achieve the purpose of slowing down the decay of goods.

Comparative Embodiment 1

[0186] In this comparative embodiment, an air electrode is prepared. The preparation process is shown in FIG. 1 and includes the following steps:

[0187] S1: preparing a first diffusion layer by the steps of: [0188] mixing 15 parts (by weight) of carbon black, 40 parts of activate carbon and 45 parts of PTFE emulsion to obtain a mixture; [0189] adding ethanol to the mixture, and roll-processing for several times to prepare the first diffusion layer.

[0190] S2: preparing a current collecting layer by the steps of: [0191] degreasing: soaking current collecting layer metal in acetone at 25? C. for 10 min; [0192] rinsing: rinsing the degreased current collecting layer metal with water for three times; [0193] acid rinsing: rinsing the rinsed current collecting layer metal with 5 mol/L hydrochloric acid aqueous solution for 10 min under ultrasonic, and rinsing with ethanol and water for 4 times; [0194] drying: drying the current collecting layer metal after acid rinsing at 60? C. for 5 h.

[0195] S3: preparing a second diffusion layer by the steps of: [0196] mixing 15 parts (by weight) of carbon black, 40 parts of activate carbon and 45 parts of PTFE emulsion to obtain a mixture; [0197] adding ethanol to the mixture, and roll-processing for several times to prepare the second diffusion layer.

[0198] S4: preparing a catalyst layer: mixing the following components in percentage by mass: microsilica powder: 12.5%, carbon black: 20%, activate carbon: 47.5%, PTFE emulsion binder: 20% under high-speed stirring to obtain a mixture, and then roll-processing the mixture for several times.

[0199] S5: preparing the air electrode: stacking sequentially the first diffusion layer 100, the current collecting layer 101, the second diffusion layer 102 and the catalyst layer 103 according to the structure shown in FIG. 2 to obtain a multilayer body, and then roll-processing the multilayer body to form the air electrode.

[0200] The differences between microsilica powder and silicon powder lie in: the main component of microsilica powder is silicon dioxide, while the main component of silicon powder is elemental silicon. Although microsilica powder or silicon powder both can be used as catalytic active substance, and no hydrogen peroxide or hydrogen peroxide ions would be produced using the both, thus the problem of chemical corrosion on anode can be avoided. However, changing microsilica powder into silicon powder is conducive to reduce the charging voltage and improve the catalytic activity.

Comparative Embodiment 2

[0201] In this comparative embodiment, an air electrode is prepared. The preparation process is shown in FIG. 1 and includes the following steps:

[0202] S1: preparing a first diffusion layer by the steps of: [0203] mixing 15 parts (by weight) of carbon black, 40 parts of activate carbon and 45 parts of PTFE emulsion to obtain a mixture; [0204] adding ethanol to the mixture, and roll-processing for several times to prepare the first diffusion layer.

[0205] S2: preparing a current collecting layer by the steps of: [0206] degreasing: soaking current collecting layer metal in acetone at 25? C. for 10 min; [0207] rinsing: rinsing the degreased current collecting layer metal with water for three times; [0208] acid rinsing: rinsing the rinsed current collecting layer metal with 5 mol/L hydrochloric acid aqueous solution for 10 min under ultrasonic, and rinsing with ethanol and water for 4 times; [0209] drying: drying the current collecting layer metal after acid rinsing at 60? C. for 5 h.

[0210] S3: preparing a second diffusion layer by the steps of: [0211] mixing 15 parts (by weight) of carbon black, 40 parts of activate carbon and 45 parts of PTFE emulsion to obtain a mixture; [0212] adding ethanol to the mixture, and roll-processing for several times to prepare the second diffusion layer.

[0213] S4: preparing a catalyst layer: mixing the following components in percentage by mass: manganese dioxide: 30%, carbon black: 10%, activate carbon: 27%, PTFE emulsion binder: 33% under high-speed stirring to obtain a mixture, and then roll-processing the mixture for several times.

[0214] S5: preparing the air electrode: stacking sequentially the first diffusion layer 100, the current collecting layer 101, the second diffusion layer 102 and the catalyst layer 103 according to the structure shown in FIG. 2 to obtain a multilayer body, and then roll-processing the multilayer body to form the air electrode.

Test Example 1

[0215] In this Text Example, the performances of the air electrodes prepared in Embodiments 1 to 3 and Comparative Embodiments 1 to 2 were tested.

[0216] The device for test is an air electrode test device having the structure shown in FIG. 3.

[0217] In test, the power 200, the air electrode 201, the anode 202 and the electrolyte 203 were assembled as shown in FIG. 3, where the anode of the power 200 was connected to the anode 202 and the cathode was connected to the air electrode 201.

[0218] De-oxygenation test: using nickel mesh as anode 202 and 20 wt % potassium carbonate solution as electrolyte, the charging voltage of the air electrode and the corrosion of the anode 202 were tested under the constant current of 150 mA, and the performance test results are shown in Table 1.

[0219] Low-temperature test: using nickel mesh as anode and 40 wt % potassium carbonate solution as electrolyte, the charging voltage was tested at 0? C.?5? C. for 10 days.

TABLE-US-00001 TABLE 1 Performance test results of the air electrodes prepared in Embodiments 1 to 3 and Comparative Embodiments 1 to 2 Components of the Comparative Comparative catalyst layer (wt %) Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Embodiment 1 Embodiment 2 Silicon powder 20 30 35 20 Alumina oxide 2 Microsilica powder 12.5 Manganese dioxide 30 Carbon black 12 10 10 12 20 10 Activate carbon 35 27 22 33 47.5 27 PTFE 33 33 33 33 20 33 Charging voltage (V) 1.680 1.623 1.754 1.662 1.780 2.136 Anode corrosion No anode No anode No anode No anode No anode Corrosion corrosion corrosion corrosion corrosion corrosion on nickel mesh anode

[0220] According to the test results in Table 1, using the air electrodes prepared in Embodiments 1 to 3 as cathode, nickel mesh as anode and 40 wt % potassium carbonate solution as electrolyte, the de-oxygenation test was continuously carried out at room temperature. After running for 30 days, the anode of the air electrodes of Embodiments 1 to 3 were free from corrosion (the reaction mechanism is the reaction process of not generating intermediate product hydrogen peroxide).

[0221] It can also be seen from Table 1 that in the air electrodes of Embodiments 1 to 3, when the content of silicon powder was 20%, the charging voltage was 1.680 V; when the content of silicon powder was 30%, the minimum charging voltage was as low as 1.623 V; and when the content of silicon powder was 35%, the charging voltage was 1.754 V. It can be shown that the above-mentioned charging voltage changed as function of the increase of the catalytic active component silicon powder in the catalyst layer, and when the content of silicon powder exceeds a certain proportion, the reaction space decreases and the catalytic efficiency reduces instead.

[0222] In Embodiment 4, the catalytic active component in the catalyst layer is the combination of silicon powder and ?-Al.sub.2O.sub.3, which is beneficial to further enhance the catalytic activity and reduce the charging voltage.

[0223] In Comparative Embodiment 1, when silicon powder is changed to microsilica powder, the charging voltage increases, indicating that the catalytic activity of microsilica powder is lower than that of silicon powder.

[0224] In Comparative Embodiment 2, manganese dioxide is used as the catalytic active component of the air electrode (the reaction mechanism is the reaction process of generating the intermediate product hydrogen peroxide). After 12 days of deoxidization test, the anode was obviously rusted, and even rusted through in severe cases.

[0225] From the above analysis, it can be known that when silicon powder is used as catalyst, the formation of peroxide at the cathode can be prevented when the air electrode undergoes electrochemical oxidation-reduction reaction, thus protecting the anode from chemical corrosion. The corrosion resistance of the air electrode of Embodiments is much better than that of Comparative Embodiment 2 in which manganese dioxide is used.

[0226] According to the results in Table 1, the charging voltage of the air electrodes prepared in Embodiments 1 to 3 of the present disclosure was 1.623 V-1.754 V under the constant current of 150 mA when using the air electrodes prepared in Embodiments 1 to 3 as cathode, nickel mesh as anode, and 40 wt % potassium carbonate solution as electrolyte. Under the same conditions, the charging voltage of the air electrode (in which manganese dioxide used as the catalytic active component) prepared in Comparative Embodiment 2 was measured to be 2.136 V. From the above it can be seen that the power consumption of the air electrodes of Embodiments 1 to 3 is greatly reduced.

Test Example 2

[0227] In this Text Example, the air electrode of Embodiment 2 is taken as reference and tested for the influence of diffusion layer thickness on charging voltage under the same conditions, and the results are shown in Table 2.

TABLE-US-00002 TABLE 2 Test results of diffusion layer thickness and charging voltage Thickness of the Charging diffusion layer Catalyst voltage 0.4 mm 30% silicon powder 1.623 0.6 mm 30% silicon powder 1.692 0.8 mm 30% silicon powder 1.736

[0228] According to the test results in Table 2, the charging voltage increases with the thickness of the diffusion layer.

[0229] In the air electrode of the present disclosure, the catalytic active substance includes silicon powder which does not participate in the reduction reaction at the cathode, so that no hydrogen peroxide or hydrogen peroxide ions are generated, and the chemical corrosion problem of the anode is avoided.

[0230] In the air electrode of the present disclosure, the catalytic active substance is silicon powder, which is less expensive and easily available, and there is large silicon resource reserve, accounting for about 26% of the shell mass; and the cost is lower than that of manganese dioxide, thus being beneficial to industrial popularization and application.

[0231] In the preparation of the air electrode of the present disclosure, the catalyst layer can be prepared by mixing silicon powder, conductive agent, activate carbon and binder in proportion and pressing, and then the air electrode according to the present disclosure can be prepared by pressing the first diffusion layer, the current collecting layer, the second diffusion layer and the catalyst layer which are stacked in sequence. The preparation process is simple to operate, which is beneficial to large-scale industrial production.

[0232] In addition, no strict preparation process condition is necessary for the air electrode, the equipment requirements are relatively low, thus the production investment can be further reduced.

[0233] When the air electrode is applied into electrochemical de-oxygenation, because the air electrode contains the catalyst layer including silicon powder as the active catalytic component, the formation of peroxide at the cathode can be avoided when the air electrode undergoes electrochemical oxidation-reduction reaction, thus protecting the anode from chemical corrosion. Using the electrode containing the catalyst layer as cathode, nickel mesh as anode and

[0234] potassium carbonate as electrolyte, de-oxygenation test was carried out at room temperature. After continuous running for 30 days, the anode had no obvious corrosion. However, if the catalyst is replaced with manganese dioxide and after the de-oxidization test runs for about 12-15 days under the same conditions, the anode would be obviously rusted and even rusted through in severe cases.

[0235] The air electrode containing the catalyst layer has lower power consumption, which can be reduced by about 20%. In an example taking nickel mesh as anode and 5%-40% potassium carbonate solution as electrolyte, the charging voltage is 1.6 V-1.9 V under the condition of constant current with current density of 40 mA-300 mA. However, under the same experimental conditions, when the catalyst is changed to manganese dioxide, the charging voltage of the module is 2.0 V-2.3 V.

[0236] The air electrode with the catalyst layer has relatively high material reliability. In an example taking nickel mesh as anode and 5%-40% potassium carbonate solution as electrolyte, the first charging voltage of the electrode containing the air electrode catalyst is 2.3 V after the experimental module is placed at 0? C.-5? C. for 3 to 10 days. With the increase of charging time, the voltage decreases continuously, and the charging voltage is stable at 1.8 V-2.0 V after running for 4 hours. However, under the same conditions, if manganese dioxide is used as air electrode catalyst, the first charging voltage of manganese dioxide catalyst air electrode is 4.5 V after the experimental module is placed at 0? C.-5? ? C. for 3 to 10 days. With the increase of charging time, the voltage decreases, and the charging voltage is stable at 3.5 V-3.8 V after running for 7 h. It can be seen that the air electrode with the above catalyst layer is more stable and reliable in the environment compared to the manganese dioxide air electrode.

[0237] The embodiments of the present disclosure have been described in detail with reference to the above description and drawings, but the present disclosure is not intended to be limited by the above embodiments, and various changes can be made without departing from the principle of the present disclosure within the scope of knowledge possessed by those skilled in the art. In addition, the embodiments of the present disclosure and the features in the embodiments can be combined with each other without conflict.