Cerium oxide / manganese oxide composite material for rapidly eliminating active free radicals of membrane electrode

Abstract

The invention discloses a cerium oxide / manganese oxide composite material for rapidly eliminating active free radicals of a membrane electrode. The cerium oxide / manganese oxide composite material comprises the following components: Ce (acac) 3 is deposited on the surface of MnO2 and is sintered at high temperature to obtain the cerium oxide / manganese oxide composite material; the preparation method of the cerium oxide / manganese oxide composite material comprises the following steps: (1) uniformly depositing Ce (acac) 3 on the surface of MnO2 by adopting a one-pot method, and then grinding to obtain precursor powder; and (2) carrying out high-temperature sintering on the precursor powder treated in the step (1) to obtain the CeO2 / MnO2 composite material. The method is simple and efficient, the composite material can be prepared through two-step treatment, CeO2 and MnO2 in the composite material have a synergistic effect, and degradation of MnO2 can be inhibited while the catalytic activity of oxidation-reduction reaction is improved, so that the service life of the aluminum-air battery is prolonged, and the discharge performance of the aluminum-air battery is optimized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new energy battery, in particular to a cerium oxide / manganese oxide composite material for quickly eliminating active free radicals of membrane electrode, and a preparation method of the composite material and an application of the composite material. BACKGROUND

[0002] Developing efficient and clean new energy technology has become the core direction of scientific research and industrial development. Aluminum-air battery has great application potential in the fields of electric vehicles, unmanned aerial vehicles and emergency power supply due to its high theoretical energy density, abundant raw material reserves and environmental friendliness. However, its commercialization process has been limited for a long time due to the slow kinetics of cathode oxygen reduction reaction and the insufficient stability of catalytic materials.

[0003] Although the traditional manganese-based catalyst is low in cost and has certain catalytic activity, it is easily degraded by free radicals in long-term operation, resulting in rapid performance degradation of the battery. At the same time, although the noble metal platinum-based catalyst has excellent performance, its high cost and resource scarcity seriously limit its large-scale application. Therefore, developing a new composite material with high catalytic efficiency and long-term stability has become a key breakthrough for promoting the practicality of aluminum-air battery. SUMMARY

[0004] In view of the above-mentioned shortcomings of the prior art, the purpose of the present application is to provide a cerium oxide / manganese oxide composite material for quickly eliminating active free radicals of membrane electrode.

[0005] A cerium oxide / manganese oxide composite material for quickly eliminating active free radicals of membrane electrode has the following components: Ce(acac)3 is deposited on the surface of MnO2 and sintered at high temperature to obtain the cerium oxide / manganese oxide composite material. The preparation of the cerium oxide / manganese oxide composite material includes the following steps:

[0006] (1) uniformly depositing Ce(acac)3 on the surface of MnO2 by one-pot method, and then grinding to obtain precursor powder;

[0007] (2) taking the precursor powder obtained by step (1) to sinter at high temperature to obtain CeO2 / MnO2 composite material.

[0008] As a further improvement of the above-mentioned scheme, in step (1), the specific operation of the one-pot method is: dissolving Ce(acac)3 into ethanol, then adding MnO2, and mixing and treating under heating condition by magnetic stirring to obtain black substance, and then grinding to obtain precursor powder.

[0009] As a further improvement of the above-mentioned scheme, the mass ratio of MnO2 and Ce(acac)3 is 5-15:1; the amount of ethanol used is 40-80 times the total amount of MnO2 and Ce(acac)3.

[0010] As a further improvement of the above-mentioned scheme, during the mixing process, the speed of magnetic stirring is 300-500 rpm, the heating temperature is 80-100℃, and the mixing is carried out until the ethanol is completely evaporated, and the obtained black substance is ground into powder in a mortar. The purpose of magnetic stirring in the present application is to obtain better homogenization effect, and the purpose of heating is to promote the evaporation of ethanol. Under the conditions of magnetic stirring and heating, Ce(acac)3 is fully dissolved in ethanol, and uniformly dispersed MnO2 forms a suspension. After the ethanol is completely evaporated, Ce(acac)3 is uniformly deposited on the surface of MnO2.

[0011] As a further improvement of the above-mentioned scheme, in step (2), the precursor powder is uniformly laid in the crucible, and the crucible is placed in a muffle furnace for high-temperature sintering treatment in an air atmosphere. In the present application, Ce(acac)3 is converted to CeO2 by high-temperature sintering, and CeO2 has unique oxygen vacancy defects and reversible Ce 3+ / Ce 4+ Redox pair, which can effectively remove free radicals in the process of oxygen reduction reaction, thereby significantly delaying the deactivation process of the catalyst. When CeO2 and MnO2 are compounded, they can form a synergistic effect. The oxygen storage property of CeO2 can stabilize the reaction intermediates and reduce the reaction energy barrier, while MnO2 provides a good electron transport network, which together improves the catalytic activity and stability.

[0012] Further, the sintering treatment is specifically operated as follows: heating at a heating rate of 1-10℃ / min to 400-500℃, holding for 2-5h, then cooling in the furnace, taking out the sample and grinding in a mortar to obtain CeO2 / MnO2 composite material. In the present application, the control of sintering conditions can realize the regulation of material microstructure and composition, ensure the uniform distribution of CeO2 on the surface of MnO2, realize the controllable optimization of material performance, and make the synergistic effect between the two phases be maximized. CeO2 / MnO2 composite material is expected to play an important role in a wider field of energy storage and conversion, promote the rapid development of clean energy technology, and be beneficial to large-scale production.

[0013] The application of a cerium oxide / manganese oxide composite material in an aluminum-air battery. The cerium oxide / manganese oxide composite material is the cerium oxide / manganese oxide composite material that rapidly eliminates active free radicals of the membrane electrode.

[0014] As a further improvement of the above-mentioned scheme, in the aluminum-air battery, the positive electrode is a membrane electrode made of a cerium oxide / manganese oxide composite material, the negative electrode is an aluminum plate, and the electrolyte is 1M potassium chloride. The membrane electrode comprises two waterproof and breathable membranes, a current collector, and a catalytic membrane; wherein carbon nanotubes, activated carbon, conductive carbon, CeO2 / MnO2 composite material, ethanol and PTFE are mixed and pressed in a ratio of 1:20-40:10-25:10-25:60-100:25-35 to obtain the catalytic membrane.

[0015] As a further improvement of the above-mentioned scheme, the current collector is located between the two waterproof and breathable membranes, and the catalytic membrane is attached to one of the catalytic membranes. The waterproof and breathable membrane, the current collector and the catalytic membrane are stacked and pressed to obtain the membrane electrode.

[0016] As a further improvement of the above-mentioned scheme, in step one, the carbon nanotubes, activated carbon, conductive carbon, CeO2 / MnO2 composite material, ethanol and PTFE are mixed uniformly to obtain a raw material. The raw material is repeatedly pressed in a coarse press until the folded thin film does not crack, and then pressed once in a fine press to obtain the catalytic membrane.

[0017] In step two, the waterproof and breathable membrane, the current collector and the catalytic membrane obtained in step one are stacked in order and pressed by a membrane combining machine to obtain the membrane electrode.

[0018] As a further improvement of the above-mentioned scheme, the thickness of the catalytic membrane is 0.1-0.2mm; and the thickness of the membrane electrode is 0.5-0.6mm.

[0019] Compared with the prior art, the present application has the following advantages:

[0020] The material of the present application combines CeO2 and MnO2, and through the synergistic effect of CeO2 and MnO2, not only improves the catalytic activity of the redox reaction, but also effectively removes free radicals (such as ·OOH) in the reaction process by using the oxygen vacancy defects of CeO2, thereby significantly inhibiting the degradation of the MnO2 catalyst, prolonging the service life of the aluminum-air battery and optimizing its discharge performance.

[0021] The preparation method of the present application is simple and efficient, which combines "one-pot method" deposition precursor and high-temperature sintering, and the composite material can be prepared through two-step processing, simplifying the complex process of traditional multi-step synthesis (such as coprecipitation, hydrothermal method). At the same time, by controlling the sintering conditions, the uniform distribution of CeO2 on the surface of MnO2 is ensured, the controllable optimization of material performance is realized, the synergistic effect between the two phases is maximized, and the scale production is facilitated.

[0022] The material of the present application can be adapted to the existing aluminum-air battery assembly process, and can be directly applied without modification of equipment, which is conducive to industrialization and promotion, and has excellent prospects. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 SEM image of the CeO2 / MnO2 composite material of Example 1 of the present application is shown.

[0024] Figure 2 Discharge curve of the membrane electrode made of the CeO2 / MnO2 composite material of Example 1 of the present application is shown.

[0025] Figure 3 Raman image of the membrane electrode made of the CeO2 / MnO2 composite material of Example 1 of the present application is shown. DETAILED DESCRIPTION

[0026] In order to make the objects, technical solutions, and advantages of the present application clearer, the following will further describe the present application with examples. The additional aspects and advantages of the present application will be partially given in the following description, partially will become obvious from the following description, or will be understood by the practice of the present application. It should be understood that the following description is only used to explain the present application, and is not used to limit the present application.

[0027] The following will describe the specific examples of the present application in detail.

[0028] Example 1

[0029] The present example provides a cerium oxide / manganese oxide composite material for quickly eliminating active free radicals of a membrane electrode, which has the following components: Ce(acac)3 is deposited on the surface of MnO2 and the cerium oxide / manganese oxide composite material is obtained by high-temperature sintering. The present example also provides a preparation method of the cerium oxide / manganese oxide composite material, which includes the following steps:

[0030] (1) 300 ml of ethanol is added to a beaker, 0.5 g of Ce(acac)3 is dissolved in the ethanol, and then 5 g of MnO2 is added. The mixture is treated by magnetic stirring under heating conditions. During the mixing treatment, the heating temperature is 100°C, the rotating speed of the magnetic stirring is 400 Rpm, and the mixing is continued until the ethanol is completely evaporated. The obtained black substance is ground into powder in a mortar to obtain a precursor powder. In the present example, the purpose of the magnetic stirring is to obtain a better homogenization effect, and the purpose of the heating is to promote the evaporation of the ethanol. Under the conditions of the magnetic stirring and the heating, the Ce(acac)3 is fully dissolved in the ethanol and uniformly dispersed in the MnO2 to form a suspension. After the ethanol is completely evaporated, the Ce(acac)3 is uniformly deposited on the surface of the MnO2.

[0031] (2) The precursor powder obtained by step (1) is uniformly spread in a crucible, and the crucible is placed in a muffle furnace for high-temperature sintering treatment in an air atmosphere. The sintering treatment is specifically performed as follows: heating at a rate of 5 ℃ / min to 450 ℃, holding for calcination for 3 h, and then cooling with the furnace. The sample is taken out, ground in a mortar, and CeO2 / MnO2 composite material is obtained.

[0032] In this embodiment, Ce(acac)3 is cerium acetylacetone hydrate, which is converted into CeO2 by high-temperature sintering. CeO2 has unique oxygen vacancy defects and reversible Ce 3+ / Ce 4+ The redox pair can effectively eliminate free radicals in the oxygen reduction reaction process, thereby significantly delaying the deactivation process of the catalyst. When CeO2 is combined with MnO2, the two can form a synergistic effect. The oxygen storage property of CeO2 can stabilize the reaction intermediates and reduce the reaction energy barrier, while MnO2 provides a good electron conduction network, which together improves the catalytic activity and stability. In addition, during the high-temperature sintering process, the control of the sintering conditions can realize the regulation of the microstructure and composition of the material, ensure the uniform distribution of CeO2 on the surface of MnO2, realize the controllable optimization of the material performance, and maximize the synergistic effect between the two phases. The CeO2 / MnO2 composite material is expected to play an important role in a wider range of energy storage and conversion fields, promote the rapid development of clean energy technology, and facilitate large-scale production.

[0033] In summary, the preparation method of this embodiment is simple and efficient, combining "one-pot" deposition of precursors and high-temperature sintering. The composite material can be prepared by two-step treatment. CeO2 is uniformly distributed on the surface of MnO2, realizing controllable optimization of material performance, maximizing the synergistic effect between the two phases, breaking through the technical barriers of traditional composite methods such as mechanical mixing or step-by-step deposition, which are difficult to achieve uniform dispersion and strong interface bonding of materials, leading to limited improvement of catalytic performance. Not only does it solve the core problem of poor stability and short service life of aluminum-air battery catalyst materials, but it also optimizes the process to reduce production costs, facilitates large-scale application, and provides an innovative solution for the practicality of new energy batteries.

[0034] Example 2

[0035] The present embodiment provides a cerium oxide / manganese oxide composite material for rapidly eliminating active free radicals of a membrane electrode, which comprises the following components: Ce(acac)3 deposited on the surface of MnO2 and obtained by high-temperature sintering to obtain the cerium oxide / manganese oxide composite material. The present embodiment also provides a preparation method of the cerium oxide / manganese oxide composite material, which comprises the following steps:

[0036] (1) Add 400 ml of ethanol into a beaker, dissolve 0.5 g of Ce(acac)3 into the ethanol, then add 7.5 g of MnO2, and the rest is the same as in Example 1 to obtain a precursor powder.

[0037] (2) The precursor powder obtained in step (1) is evenly spread in a crucible, and the crucible is placed in a muffle furnace for high-temperature sintering treatment in an air atmosphere. The sintering treatment is specifically performed as follows: the temperature is raised to 400°C at a rate of 1°C / min, and the sample is calcined for 2 h, then cooled with the furnace, taken out and ground in a mortar to obtain a CeO2 / MnO2 composite material.

[0038] Example 3

[0039] The present example provides a CeO2 / MnO2 composite material for quickly eliminating active radicals of a membrane electrode, which comprises the following components: Ce(acac)3 deposited on the surface of MnO2 and obtained by high-temperature sintering. The present example also provides a preparation method of the CeO2 / MnO2 composite material, which comprises the following steps:

[0040] (1) Add 300 ml of ethanol into a beaker, dissolve 0.5 g of Ce(acac)3 into the ethanol, then add 4.5 g of MnO2, and mix under magnetic stirring at a heating temperature of 85°C and a stirring speed of 500 Rpm. After the ethanol is completely evaporated, the obtained black substance is ground into a powder in a mortar to obtain a precursor powder.

[0041] (2) The precursor powder obtained in step (1) is evenly spread in a crucible, and the crucible is placed in a muffle furnace for high-temperature sintering treatment in an air atmosphere. The sintering treatment is specifically performed as follows: the temperature is raised to 500°C at a rate of 10°C / min, and the sample is calcined for 5 h, then cooled with the furnace, taken out and ground in a mortar to obtain a CeO2 / MnO2 composite material.

[0042] Example 4

[0043] The present example provides an application of the CeO2 / MnO2 composite material in an aluminum-air battery. When the CeO2 / MnO2 composite material is applied in an aluminum-air battery, the positive electrode of the aluminum-air battery is a membrane electrode prepared from the CeO2 / MnO2 composite material, the negative electrode is an aluminum plate, and the electrolyte is 1M potassium chloride. In actual application, the CeO2 / MnO2 composite material can be adapted to the existing assembly process of the aluminum-air battery, and can be directly applied without modification of equipment, which is conducive to industrialization and has excellent prospects.

[0044] The membrane electrode comprises two waterproof and air-permeable membranes, a current collector and a catalytic membrane. The current collector is located between the two waterproof and air-permeable membranes, and the catalytic membrane is attached to one of the two waterproof and air-permeable membranes. The waterproof and air-permeable membrane, the current collector and the catalytic membrane are stacked and then pressed to obtain the membrane electrode. The current collector in this embodiment is a thin film made of conductive material, which can concentrate the current in the battery to the electrode, thereby improving the output power and energy density of the battery.

[0045] The membrane electrode in this embodiment is prepared according to the following process:

[0046] Step 1: 0.2 g of carbon nanotubes, 6 g of activated carbon, 3.6 g of conductive carbon, 3.6 g of CeO2 / MnO2 composite material prepared by the preparation method of any one of claims 1 to 3, 17 g of ethanol and 6 g of PTFE are uniformly mixed to obtain a raw material. The raw material is repeatedly pressed in a coarse press until the folded thin film does not crack, and then pressed once in a fine press to obtain a catalytic membrane with a thickness of 0.15 mm. In this embodiment, the coarse press provides a pressure of at least 10 tons, and the fine press provides a pressure of 50 tons. The coarse press and the fine press cooperate to press the membrane electrode raw material into a catalytic membrane with a thickness of millimeters. In this embodiment, the catalytic membrane electrode prepared by the film pressing process has excellent mechanical strength and electrochemical performance, providing a feasible solution for large-scale production of aluminum-air batteries.

[0047] Step 2: The waterproof and air-permeable membrane, the current collector and the catalytic membrane obtained in step 1 are stacked in order and pressed in a film combining machine to obtain a membrane electrode with a thickness of 0.56 mm. The film combining machine is used to provide a pressure of 50 tons.

[0048] The CeO2 / MnO2 composite material prepared in Example 1 is tested as follows, Figure 1 The SEM image of the CeO2 / MnO2 composite material is shown in Figure a, which is a macroscopic image of the CeO2 / MnO2 composite material, and Figure b is a microscopic and mapping image of the CeO2 / MnO2 composite material. From the SEM image, it can be seen that CeO2 is uniformly dispersed on the surface of MnO2, which proves that the preparation method of the present application can realize controllable optimization of material performance, maximize the synergistic effect between the two phases, and break through the technical barriers of traditional composite methods such as mechanical mixing or step-by-step deposition, which are difficult to realize uniform dispersion and strong interface bonding of materials, resulting in limited improvement of catalytic performance.

[0049] The CeO2 / MnO2 composite material of Example 1 is used to make a membrane electrode, which is assembled into an aluminum-air battery. The electrolyte is a 1M potassium chloride solution. The discharge test is carried out at a current density of 5 mA cm -2 Figure 2 Figure 2 ​​The discharge curves of the film electrode in 1M potassium chloride solution are shown in Figure a, which is the discharge curve of the first 50h, and Figure b is the discharge curve of the last 50h. Figure 2 It can be seen that the discharge voltage of the first 50h has little change, while the discharge voltage of the last 50h is much higher than that of the MnO2 film electrode. In the actual test process, the performance of the MnO2 film electrode deteriorates, which causes the need to add electrolyte to work normally. The carbon peaks of the film electrode at 0h, 50h and 100h are tested by Raman, and the test results are shown in Figure Figure 3 , in which I(D) / I(G) represents the proportion of amorphous carbon in the film electrode. Analysis Figure 3 It can be seen that the increase of amorphous carbon in the film electrode is caused by the failure of the MnO2 film electrode to remove free radicals in time, which finally causes the catalyst to fall off from the film electrode and reduces the catalytic performance. Combined with Figure 2 and Figure 3 , it is proved that the CeO2 / MnO2 composite material of the present application can efficiently remove free radicals in the oxygen reduction reaction, inhibit the degradation of MnO2 material, prolong the service life of the aluminum-air battery and optimize its discharge performance, and significantly improve the catalytic activity.

[0050] The above examples are only the preferred embodiments of the present application, and any simple modification, modification and alternative change made according to the technical essence of the present application to the above examples are within the scope of the technical scheme of the present application.

Claims

1. A cerium oxide / manganese oxide composite material for rapidly eliminating active radicals of a membrane electrode, characterized by, The cerium oxide / manganese oxide composite material has the following components: Ce(acac)3 is deposited on the surface of MnO2 and high-temperature sintering is performed to obtain the cerium oxide / manganese oxide composite material; The preparation of the cerium oxide / manganese oxide composite material comprises the following steps: (1) uniformly depositing Ce(acac)3 on the surface of MnO2 by one-pot method, and then grinding to obtain a precursor powder; (2) taking the precursor powder obtained in step (1) to perform high-temperature sintering to obtain a CeO2 / MnO2 composite material.

2. The cerium oxide / manganese oxide composite material according to claim 1, characterized in that, In step (1), the specific operation of the one-pot method is as follows: Ce(acac)3 is dissolved in ethanol, then MnO2 is added, and the mixture is treated by magnetic stirring under heating conditions, and the obtained black substance is ground to obtain a precursor powder.

3. The cerium oxide / manganese oxide composite material according to claim 2, characterized in that, The mass ratio of MnO2 to Ce(acac)3 is 5-15:1; the amount of ethanol used is 40-80 times the total amount of MnO2 and Ce(acac)3; in the mixing process, the stirring speed is 300-500 rpm, the heating temperature is 80-100℃, and the mixture is mixed until the ethanol is completely evaporated, and the obtained black substance is placed in a mortar for grinding into powder.

4. The cerium oxide / manganese oxide composite material according to claim 1, characterized by In step (2), the precursor powder is uniformly placed in a crucible, and the crucible is placed in a muffle furnace for high-temperature sintering treatment in an air atmosphere.

5. The cerium oxide / manganese oxide composite material according to claim 4, characterized in that The specific operation of the sintering treatment is as follows: the temperature is raised at a rate of 1-10℃ / min to 400-500℃, and the sample is calcined for 2-5h, then cooled in the furnace, taken out and ground in a mortar to obtain a CeO2 / MnO2 composite material.

6. Use of a cerium oxide / manganese oxide composite material, characterized in that The cerium oxide / manganese oxide composite material is applied in an aluminum-air battery; the cerium oxide / manganese oxide composite material is a cerium oxide / manganese oxide composite material for rapidly eliminating active radicals of a membrane electrode as claimed in any one of claims 1-5.

7. Use of cerium oxide / manganese oxide composite according to claim 6, characterized in that In the aluminum-air battery, the positive electrode is a membrane electrode prepared by using the cerium oxide / manganese oxide composite material, the negative electrode is an aluminum plate, and the electrolyte is 1M potassium chloride; the membrane electrode comprises two waterproof and air-permeable membranes, a current collector, and a catalytic membrane; wherein carbon nanotubes, activated carbon, conductive carbon, CeO2 / MnO2 composite material, ethanol, and PTFE are mixed and pressed in a ratio of 1:20-40:10-25:10-25:60-100:25-35 to obtain the catalytic membrane.

8. Use of cerium oxide / manganese oxide composite according to claim 7, characterized in that The current collector is located between the two waterproof and air-permeable membranes, and the catalytic membrane is attached to one of the catalytic membranes; the waterproof and air-permeable membranes, the current collector, and the catalytic membrane are stacked and then pressed to obtain the membrane electrode.

9. Use of cerium oxide / manganese oxide composite according to claim 8, characterized in that The manufacturing process of the membrane electrode is as follows: Step one: uniformly mix carbon nanotubes, activated carbon, conductive carbon, CeO2 / MnO2 composite material, ethanol, and PTFE to obtain raw materials, and repeatedly press the raw materials in a coarse press until there are no cracks when the film is folded in half, and then press the film once in a fine press to obtain a catalytic membrane; Step two: stack the waterproof and air-permeable membranes, the current collector, and the catalytic membrane obtained in step one in order, and press them in a membrane combining machine to obtain a membrane electrode.

10. Use of cerium oxide / manganese oxide composite material according to claim 9, characterized in that, The thickness of the catalytic membrane is 0.1-0.2mm; and the thickness of the membrane electrode is 0.5-0.6mm.

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