Zinc-air battery catalyst and preparation method thereof

Abstract

The present invention discloses a zinc-air battery catalyst and a preparation method thereof, which includes two-dimensional carbon nanosheets and a MoC / MoN heterojunction, and the MoC / MoN heterojunction is attached to the two-dimensional carbon nanosheets. The prepared zinc-air battery catalyst includes two-dimensional carbon nanosheets and a MoC / MoN heterojunction, and the MoC / MoN heterojunction is attached to the two-dimensional carbon nanosheets. When this catalyst is applied to a zinc-air battery, at a current density of 10 mA cm-2, the charge-discharge potential difference is 0.44 V, and after 300 h of cycling, the charge-discharge voltage difference is basically unchanged, being 0.47 V, having remarkable stability and high efficiency, and its overall comprehensive performance is superior to that of a commercial platinum-carbon electrode; moreover, the zinc-air battery catalyst of the present invention can not only meet the actual application requirements of zinc-air batteries, solve the problems of reaction rate hysteresis and instability existing in zinc-air batteries in the prior art, but also be synthesized in large quantities to reduce the preparation cost.

Description

Technical Field

[0001] The present invention relates to the field of new energy, and in particular to a zinc-air battery catalyst and a preparation method thereof. Background Art

[0002] With the rapid development of economy and society, traditional non-renewable fossil fuels can no longer meet the needs of contemporary people. At the same time, the harmful substances released by fossil fuels during use will also cause serious pollution problems. Therefore, energy crisis and environmental pollution have become two major problems for the development and progress of the world today. The development of sustainable clean energy production, storage and conversion technology is a technology that needs to be solved urgently. Among various energy conversion technologies, zinc-air batteries, as a special fuel cell, show the advantages of high energy density, low equilibrium potential, stable discharge voltage, long service life, etc., and have become a very promising electrochemical energy storage technology. Its theoretical specific energy density is 1084Wh kg -1 , which is much higher than the energy density of current lithium-ion batteries. In addition, its safety, abundant zinc ore reserves, low price and environmental friendliness further guarantee its long-term development in the energy market. These huge application potentials make the market prospects of zinc-air batteries very broad.

[0003] For zinc-air batteries, one of the key factors that determine their performance is the "air electrode". 2 +4H + →2H 2 O) is a complex process involving 4 electron transfers, and the hysteresis of its reaction rate seriously restricts the development of zinc-air batteries. Therefore, exploring efficient, stable, and low-cost non-precious metal catalysts is the current research focus of zinc-air batteries. Summary of the invention

[0004] Based on this, in order to solve the problem of reaction rate hysteresis and instability of zinc-air batteries in the prior art, the present invention provides a zinc-air battery catalyst and a preparation method thereof, and the specific technical scheme is as follows:

[0005] A zinc-air battery catalyst comprises a two-dimensional carbon nanosheet and a MoC / MoN heterojunction, wherein the MoC / MoN heterojunction is attached to the two-dimensional carbon nanosheet.

[0006] Furthermore, in terms of weight ratio, the two-dimensional carbon nanosheets are 50 to 80 parts, the MoC / MoN heterojunction is 20 to 50 parts, and in the MoC / MoN heterojunction, the mass ratio of MoC to MoN is 1:1-2:1.

[0007] In addition, the present invention also provides a method for preparing a zinc-air battery catalyst, comprising the following steps:

[0008] Mixing a carbon source, an inorganic salt, a surfactant and a first molybdenum source to obtain a mixture A;

[0009] Adding a solvent to the mixture A and mixing well to obtain a mixture B;

[0010] The mixture B is subjected to ball milling and a first drying treatment, and then placed in a sealed stainless steel container, and then placed in a programmed furnace for solid phase pyrolysis, and washed to obtain a composite material of two-dimensional carbon nanosheets loaded with MoC particles;

[0011] The composite material of the two-dimensional carbon nanosheet loaded with MoC particles is dispersed in an ethanol aqueous solution, and then evenly mixed with a second molybdenum source. After a hydrothermal reaction, a second drying treatment, and a nitridation treatment, a MoC / MoN heterojunction is attached to the two-dimensional carbon nanosheet to obtain a zinc-air battery catalyst.

[0012] Furthermore, the carbon source is a mixture of urea and glucose, and the mass ratio of the urea to the glucose is 5:1-15:1.

[0013] Furthermore, the inorganic salt is one of sodium chloride and potassium chloride or a mixture of the two, and the mass ratio of the carbon source to the inorganic salt is 1:2.5-1:5.

[0014] Furthermore, the surfactant is one of PEG and PVA or a mixture of the two, and the mass ratio of the carbon source to the surfactant is 15:1-30:1.

[0015] Furthermore, the first molybdenum source and the second molybdenum source are both ammonium molybdate.

[0016] Furthermore, the solid-phase pyrolysis adopts a gradient heating method, which includes a first gradient, a second gradient and a third gradient, and the temperature of the first gradient is 500°C to 550°C, the insulation time is 1h-5h, and the heating rate is 2°C / min to 10°C / min; the temperature of the second gradient is 650°C to 800°C, the insulation time is 1h-5h, and the heating rate is 1°C / min to 6°C / min; the third gradient is 850°C to 900°C, the insulation time is 1h to 5h, and the heating rate is 1°C / min to 6°C / min.

[0017] Furthermore, the temperature of the hydrothermal reaction is 180° C. to 200° C., and the time of the hydrothermal reaction is 8 h to 15 h.

[0018] Furthermore, the conditions of the nitriding treatment are: ammonia atmosphere, a holding temperature of 600°C to 700°C, a holding time of 4h-8h, and a heating rate of 1°C / min to 5°C / min.

[0019] The zinc-air battery catalyst prepared in the above scheme includes a two-dimensional carbon nanosheet and a MoC / MoN heterojunction, wherein the MoC / MoN heterojunction is attached to the two-dimensional carbon nanosheet. When the catalyst is applied to a zinc-air battery, the catalyst has a high conductivity at 10 mA cm -2 At a current density of , the charge-discharge potential difference is 0.44V, and after 300 h of cycles, the charge-discharge voltage difference is basically unchanged at 0.47V, with significant stability and high efficiency, and its overall comprehensive performance is better than that of commercial platinum-carbon electrodes; and the zinc-air battery catalyst of the present invention can not only meet the actual application needs of zinc-air batteries, solve the problems of reaction rate hysteresis and instability of zinc-air batteries in the prior art, but also can be synthesized in large quantities to reduce preparation costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is the XRD pattern of the zinc-air battery catalyst prepared in Example 1 of the present invention;

[0021] Figure 2 is a TEM image of the zinc-air battery catalyst prepared in Example 1 of the present invention;

[0022] Figure 3 This is a STEM high-resolution image of the zinc-air battery catalyst prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with its embodiments. It should be understood that the specific implementation methods described herein are only used to explain the present invention and do not limit the protection scope of the present invention.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0025] A zinc-air battery catalyst in one embodiment of the present invention comprises a two-dimensional carbon nanosheet and a MoC / MoN heterojunction, wherein the MoC / MoN heterojunction is attached to the two-dimensional carbon nanosheet.

[0026] In one of the embodiments, the two-dimensional carbon nanosheets are 50 to 80 parts, preferably 60 to 70 parts, and the MoC / MoN heterojunction is 20 to 50 parts, preferably 30 to 40 parts, in terms of weight ratio. In addition, in the MoC / MoN heterojunction, the mass ratio of MoC to MoN is 1:1-2:1.

[0027] In addition, the present invention also provides a method for preparing a zinc-air battery catalyst, comprising the following steps:

[0028] Mixing a carbon source, an inorganic salt, a surfactant and a first molybdenum source to obtain a mixture A;

[0029] Adding a solvent to the mixture A and mixing well to obtain a mixture B;

[0030] The mixture B is subjected to ball milling and a first drying treatment, and then placed in a sealed stainless steel container, and then placed in a programmed furnace for solid phase pyrolysis, and washed to obtain a composite material of two-dimensional carbon nanosheets loaded with MoC particles;

[0031] The composite material of the two-dimensional carbon nanosheet loaded with MoC particles is dispersed in an ethanol aqueous solution, and then evenly mixed with a second molybdenum source. After a hydrothermal reaction, a second drying treatment, and a nitridation treatment, a MoC / MoN heterojunction is attached to the two-dimensional carbon nanosheet to obtain a zinc-air battery catalyst.

[0032] In one embodiment, the carbon source is a mixture of urea and glucose, and the mass ratio of the urea to the glucose is 5:1-15:1.

[0033] In one embodiment, the inorganic salt is sodium chloride, potassium chloride or a mixture of the two, and the mass ratio of the carbon source to the inorganic salt is 1:2.5-1:5, preferably 1:3-1:4.

[0034] In one embodiment, the surfactant is one or a mixture of PEG, PVA, and the mass ratio of the carbon source to the surfactant is 15:1-30:1, preferably 20:1-25:1.

[0035] In one embodiment, the solvent is ultrapure water, methanol, ethanol or a mixture of the two or more thereof.

[0036] In one embodiment, the mass ratio of the carbon source to the solvent is 1:1-1:3, preferably 1:1.5-1:2.5.

[0037] In one embodiment, the mass ratio of the composite material of the two-dimensional carbon nanosheets loaded with MoC particles to the second molybdenum source is 1:2-3:1, preferably 1:1.5-1.8:1.

[0038] In one embodiment, the first molybdenum source and the second molybdenum source are both ammonium molybdate.

[0039] In one embodiment, the ball milling treatment time is 2h to 6h.

[0040] In one embodiment, the temperature of the first drying process is 100°C to 150°C.

[0041] In one embodiment, the solid-phase pyrolysis adopts a gradient heating method, which includes a first gradient, a second gradient and a third gradient, and the temperature of the first gradient is 500℃~550℃, the insulation time is 1h-5h, and the heating rate is 2℃ / min~10℃ / min; the temperature of the second gradient is 650℃~800℃, the insulation time is 1h-5h, and the heating rate is 1℃ / min~6℃ / min; the third gradient is 850℃~900℃, the insulation time is 1h~5h, and the heating rate is 1℃ / min~6℃ / min.

[0042] In one embodiment, in the ethanol aqueous solution, the volume ratio of water to ethanol is 7-8:2-3.

[0043] In one embodiment, the temperature of the hydrothermal reaction is 180° C. to 200° C., and the time of the hydrothermal reaction is 8 h to 15 h.

[0044] In one of the embodiments, the conditions of the nitridation treatment are: ammonia atmosphere, a holding temperature of 600°C to 700°C, a holding time of 4h-8h, and a heating rate of 1°C / min to 5°C / min.

[0045] The zinc-air battery catalyst prepared in the above scheme includes a two-dimensional carbon nanosheet and a MoC / MoN heterojunction, wherein the MoC / MoN heterojunction is attached to the two-dimensional carbon nanosheet. When the catalyst is applied to a zinc-air battery, the catalyst has a high conductivity at 10 mA cm -2 At a current density of , the charge-discharge potential difference is 0.44V, and after 300 h of cycles, the charge-discharge voltage difference is basically unchanged at 0.47V, with significant stability and high efficiency, and its overall comprehensive performance is better than that of commercial platinum-carbon electrodes, and it has excellent electrocatalytic activity in both OER and ORR. The zinc-air battery catalyst of the present invention can not only meet the actual application needs of zinc-air batteries, solve the problems of reaction rate hysteresis and instability of zinc-air batteries in the prior art, but also can be synthesized in large quantities to reduce the preparation cost.

[0046] The embodiments of the present invention will be described in detail below with reference to specific examples.

[0047] Embodiment 1:

[0048] A method for preparing a zinc-air battery catalyst comprises the following steps:

[0049] 10 g of urea, 1 g of glucose, 0.988 g of ammonium molybdate (ammonium molybdate tetrahydrate), 0.5 g of PEG-4000 and 40 g of sodium chloride were mixed to obtain a mixture A;

[0050] Add 20 mL of deionized water to the mixture A and mix well to obtain a mixture B;

[0051] The mixture B is ball-milled for 4 hours, and then rapidly dried at 130° C., and then placed in a stainless steel sealed container under an argon atmosphere, and then placed in a program furnace, and heated to 550° C. at 5° C. / min and kept warm for 2 hours, and then heated to 750° C. at 2° C. / min and kept warm for 2 hours, and then heated to 900° C. at 5° C. / min and kept warm for 2 hours, and then cooled, and washed with ultrapure water to remove sodium chloride, to obtain a composite material of two-dimensional carbon nanosheets loaded with MoC particles, and the mass ratio of MoC in the obtained composite material of two-dimensional carbon nanosheets loaded with MoC particles is 20%;

[0052] 0.8 g of the composite material of the two-dimensional carbon nanosheet loaded with MoC particles prepared above was dispersed in 70 mL of water and 20 mL of ethanol aqueous solution, and then 0.6175 g of ammonium molybdate was added, ultrasonically dispersed for 1 hour, hydrothermally reacted at 180° C. for 12 hours, dried in a forced air drying oven at 80° C. for 8 hours, and then nitrided at 650° C. in an ammonia atmosphere for 5 hours, and the heating rate of the nitridation treatment was 3° C. / min. After cooling, a MoC / MoN heterojunction was attached to the two-dimensional carbon nanosheet to obtain a zinc-air battery catalyst.

[0053] The XRD diagram of the zinc-air battery catalyst in Example 1 is as follows: Figure 1 As shown, from Figure 1 It can be seen that the zinc-air battery catalyst in Example 1 is loaded with MoC and MoN. Figure 2 is a TEM schematic diagram of the zinc-air battery catalyst prepared in Example 1, Figure 3 is a STEM schematic diagram of the zinc-air battery catalyst prepared in Example 1, from Figure 2-3 It can be seen that the surface of the two-dimensional carbon material is loaded with MoC / MoN heterojunction, and Figure 3 The high-resolution image can further confirm that the material is indeed a MoC / MoN lattice. In addition, through the amount of molybdenum source added and the mass change, it can be determined that the MoC / MoN mass ratio is 37.8%, MoC is 15.5%, and MoN is 22.3%. The zinc-air battery catalyst in Example 1 has excellent electrochemical performance when applied to zinc-air batteries. -2At a current density of , the charge-discharge potential difference is 0.39V, and after 300h of cycling, the charge-discharge voltage difference remains basically unchanged at 0.41V.

[0054] Embodiment 2:

[0055] A method for preparing a zinc-air battery catalyst comprises the following steps:

[0056] 10 g of urea, 1.2 g of glucose, 1.235 g of ammonium molybdate (ammonium molybdate tetrahydrate), 0.45 g of PEG-4000 and 40 g of potassium chloride were mixed to obtain a mixture A;

[0057] Add 20 mL of deionized water to the mixture A and mix well to obtain a mixture B;

[0058] The mixture B was ball-milled for 4 hours, and then rapidly dried at 130° C., and then placed in a stainless steel sealed container under an argon atmosphere, and then placed in a program furnace, and heated to 550° C. at 5° C. / min and kept warm for 3 hours, and then heated to 700° C. at 5° C. / min and kept warm for 2 hours, and then heated to 900° C. at 2° C. / min and kept warm for 1 hour, and after cooling, potassium chloride was washed away with ultrapure water to obtain a composite material of two-dimensional carbon nanosheets loaded with MoC particles, and the mass ratio of MoC in the composite material of two-dimensional carbon nanosheets loaded with MoC particles was 25.7%;

[0059] 0.8 g of the composite material of the two-dimensional carbon nanosheet loaded with MoC prepared above was dispersed in 70 mL of water and 20 mL of ethanol aqueous solution, and then 0.864 g of ammonium molybdate was added, ultrasonically dispersed for 1 hour, hydrothermally reacted at 180° C. for 12 hours, dried in a forced air drying oven at 80° C. for 8 hours, and then nitrided at 700° C. in an ammonia atmosphere for 4 hours, and the heating rate of the nitriding treatment was 2° C. / min. After cooling, a MoC / MoN heterojunction was attached to the two-dimensional carbon nanosheet to obtain a zinc-air battery catalyst.

[0060] In Example 2, the MoC / MoN heterojunction accounts for 46.4% of the total mass of the zinc-air battery catalyst, MoC accounts for 18.5% of the total mass of the zinc-air battery catalyst, and MoN accounts for 27.9% of the total mass of the zinc-air battery catalyst. The zinc-air battery catalyst prepared in Example 2 has excellent electrochemical performance when applied to zinc-air batteries. -2 At a current density of , the charge-discharge potential difference is 0.43V, and after 300h of cycling, the charge-discharge voltage difference remains basically unchanged at 0.45V.

[0061] Embodiment 3:

[0062] A method for preparing a zinc-air battery catalyst comprises the following steps:

[0063] 12 g of urea, 0.8 g of glucose, 0.741 g of ammonium molybdate (ammonium molybdate tetrahydrate), 0.5 g of PVA and 59 g of sodium chloride were mixed to obtain a mixture A;

[0064] Add 25 mL of deionized water to the mixture A to obtain a mixture B;

[0065] The mixture B was ball-milled for 5 hours, and then rapidly dried at 150° C., and then placed in a stainless steel sealed container under an argon atmosphere, and then placed in a program furnace, and heated to 500° C. at 3° C. / min and kept warm for 2 hours, and then heated to 800° C. at 3° C. / min and kept warm for 1.5 hours, and then heated to 900° C. at 5° C. / min and kept warm for 2 hours, and after cooling, the sodium chloride was washed away with ultrapure water to obtain a composite material of two-dimensional carbon nanosheets loaded with MoC particles, and the mass ratio of MoC particles in the obtained two-dimensional carbon nanosheets loaded with MoC particles was 20%;

[0066] 0.8 g of the composite material of the two-dimensional carbon nanosheet loaded with MoC particles prepared above was dispersed in 70 mL of water and 20 mL of ethanol aqueous solution, and then 0.3088 g of ammonium molybdate was added, ultrasonically dispersed for 1 hour, and then hydrothermally reacted at 200°C for 8 hours. After drying in a forced air drying oven at 80°C for 8 hours, it was nitrided at 700°C in an ammonia atmosphere for 4 hours, and the nitridation treatment heating rate was 2°C / min. After cooling, a MoC / MoN heterojunction was obtained attached to the two-dimensional carbon nanosheet to obtain a zinc-air battery catalyst.

[0067] In Example 3, the MoC / MoN heterojunction accounts for 24.5% of the total mass of the zinc-air battery catalyst, MoC accounts for 12.4% of the total mass of the zinc-air battery catalyst, and MoN accounts for 12.1% of the total mass of the zinc-air battery catalyst. The zinc-air battery prepared by applying the catalyst of the zinc-air battery of Example 3 has excellent electrochemical performance, which is 10 mA cm -2 At a current density of , the charge-discharge potential difference is 0.42V, and after 300h of cycling, the charge-discharge voltage difference remains basically unchanged at 0.47V.

[0068] Comparative Example 1:

[0069] A method for preparing a zinc-air battery catalyst comprises the following steps:

[0070] 10g urea, 1g glucose, 0.988g ammonium molybdate (ammonium molybdate tetrahydrate), 0.5g PEG-4000 and 40g sodium chloride were mixed, 20mL deionized water was added, ball milled for 4h, and then quickly dried at 130°C. Then, it was placed in a stainless steel sealed container under an argon atmosphere, and then placed in a program furnace, heated to 550°C at 5°C / min and kept warm for 2h, then heated to 750°C at 2°C / min and kept warm for 2h, then heated to 900°C at 5°C / min and kept warm for 2h. After cooling, the sodium chloride was washed off with ultrapure water to obtain a composite catalyst, and the mass of MoC particles in the composite catalyst accounted for 20% of the composite catalyst.

[0071] The composite catalyst material in Example 1 is used as a catalyst for a zinc-air battery and is applied to the preparation of a zinc-air battery. At a current density of 10 mA cm-2, the charge-discharge potential difference is 0.71 V. After 30 h of cycling, the charge-discharge voltage difference is 0.83 V.

[0072] Comparative Example 2:

[0073] A method for preparing a zinc-air battery catalyst comprises the following steps:

[0074] 10 g urea, 1 g glucose, 0.5 g PEG-4000 and 40 g sodium chloride were mixed, 20 mL deionized water was added, ball milled for 4 h, and then quickly dried at 130 ° C. Then, placed in a stainless steel sealed container under argon atmosphere, and then placed in a program furnace, heated to 550 ° C at 5 ° C / min and kept warm for 2 h, then heated to 750 ° C at 2 ° C / min and kept warm for 2 h, then heated to 900 ° C at 5 ° C / min and kept warm for 2 h, and then cooled, washed with ultrapure water to remove sodium chloride;

[0075] Weigh 0.8 g of the prepared two-dimensional carbon nanosheets and disperse them in 70 mL of water and 20 mL of ethanol aqueous solution, then add 0.6175 g of ammonium molybdate, ultrasonically disperse for 1 hour, then hydrothermally react at 180°C for 12 hours, then dry in a forced air drying oven at 80°C for 8 hours, and then keep warm at 650°C in an ammonia atmosphere for 5 hours, with a heating rate of 3°C / min. After cooling, a two-dimensional carbon nanosheet-loaded MoN composite catalyst is obtained, in which MoN accounts for 22.3% of the two-dimensional carbon nanosheet-loaded MoN composite catalyst.

[0076] The two-dimensional carbon nanosheet-supported MoN composite catalyst in Comparative Example 2 was applied to the prepared zinc-air battery. -2 At a current density of , the charge-discharge potential difference is 0.79V, and after 30 h of cycles, the charge-discharge voltage difference is 0.87V.

[0077] Comparative Example 3:

[0078] A method for preparing a zinc-air battery catalyst comprises the following steps:

[0079] 10g urea, 1g glucose, 0.5g PEG-4000 and 40g sodium chloride were added with 20mL deionized water, ball-milled for 4h, and then quickly dried at 130℃. Then, placed in a stainless steel sealed container under argon atmosphere, and then placed in a programmed furnace, heated to 550℃ at 5℃ / min and kept warm for 2h, then heated to 750℃ at 2℃ / min and kept warm for 2h, then heated to 900℃ at 5℃ / min and kept warm for 2h. After cooling, the sodium chloride was washed away with ultrapure water. The obtained carbon material had a charge and discharge potential difference of 1.07V at a current density of 10mA cm-2, and after 1h of cycle, the charge and discharge voltage difference rapidly increased to 1.57V.

[0080] Comparative Example 4:

[0081] A method for preparing a zinc-air battery catalyst comprises the following steps:

[0082] Pure two-dimensional carbon nanosheets were prepared by the same method as in the comparative example, and then the obtained two-dimensional carbon nanosheets were uniformly mixed with the commercial molybdenum carbide and commercial molybdenum nitride in the same proportion as in Example 1, and the obtained composite material was used as a zinc-air battery catalyst. The charge and discharge potential difference of the zinc-air battery was 0.86V, and after 10h of cycle, the charge and discharge voltage was 1.53V.

[0083] Comparative Example 5:

[0084] A method for preparing a zinc-air battery catalyst comprises the following steps:

[0085] 10g urea, 1g glucose, 1.5438g ammonium molybdate (ammonium molybdate tetrahydrate), 0.5g PEG-4000 and 40g sodium chloride were weighed, 20mL deionized water was added, ball milled for 4h, and then quickly dried at 130°C, and then placed in a stainless steel sealed container under an argon atmosphere, and then placed in a program furnace, heated to 550°C at 5°C / min and kept warm for 2h, then heated to 750°C at 2°C / min and kept warm for 2h, and then heated to 900°C at 5°C / min and kept warm for 2h. After cooling, the sodium chloride was washed off with ultrapure water to obtain a composite material of two-dimensional carbon nanosheets loaded with MoC, and the mass ratio of MoC in the obtained composite material was 31.1%;

[0086] 0.8 g of the above-prepared two-dimensional carbon nanosheet-loaded MoC composite material was weighed and dispersed in 70 mL of water and 20 mL of ethanol aqueous solution, and then 0.988 g of ammonium molybdate was added and ultrasonically dispersed for 1 hour, and then hydrothermally reacted at 180°C for 12 hours, dried in a blast drying oven at 80°C for 8 hours, and then kept warm at 650°C in an ammonia atmosphere for 5 hours, with a heating rate of 3°C / min. After cooling, a MoC / MoN heterojunction was obtained attached to the two-dimensional carbon nanosheet to obtain a zinc-air battery catalyst.

[0087] In Comparative Example 5, MoC / MoN accounts for 51.9% of the zinc-air battery catalyst, MoC accounts for 21.5% of the zinc-air battery catalyst, and MoN accounts for 30.4% of the zinc-air battery catalyst. The catalyst of the zinc-air battery in Comparative Example 5 is used to prepare a zinc-air battery, which has a high conductivity at 10 mA cm -2 At a current density of , the charge and discharge potential difference is 0.67V, and after 300h of cycling, the charge and discharge voltage difference is 0.79V. It can be seen that the initial charge and discharge potential difference and the cycle stability are significantly worse than those of the embodiment of this patent.

[0088] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0089] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A zinc-air battery catalyst, characterized in that The zinc-air battery catalyst includes a two-dimensional carbon nanosheet and a MoC / MoN heterojunction, and the MoC / MoN heterojunction is attached to the two-dimensional carbon nanosheet; In terms of weight ratio, the two-dimensional carbon nanosheets are 50 to 80 parts, the MoC / MoN heterojunction is 20 to 50 parts, and the mass ratio of MoC to MoN in the MoC / MoN heterojunction is 1:1-2:

1.

2. A method for preparing a zinc-air battery catalyst as claimed in claim 1, characterized in that: The following steps are involved: Mixing a carbon source, an inorganic salt, a surfactant, and a first molybdenum source to obtain a mixture A; adding a solvent to the mixture A and mixing uniformly to obtain a mixture B; The mixture B is ball-milled and dried, and then placed in a sealed stainless steel container. The mixture is then solid-phase pyrolyzed in a programmed furnace, and washed to obtain a composite material of two-dimensional carbon nanosheets loaded with MoC particles. The composite material of the two-dimensional carbon nanosheets loaded with MoC particles is dispersed in an ethanol aqueous solution and then uniformly mixed with a second molybdenum source. After a hydrothermal reaction, a second drying treatment, and a nitridation treatment, a MoC / MoN heterojunction is attached to the two-dimensional carbon nanosheets to obtain a zinc-air battery catalyst.

3. The method for preparing a zinc-air battery catalyst according to claim 2, wherein: The carbon source is a mixture of urea and glucose, and the mass ratio of the urea to the glucose is 5:1-15:

1.

4. The method for preparing a zinc-air battery catalyst according to claim 2, wherein: The inorganic salt is one of sodium chloride and potassium chloride or a mixture of the two, and the mass ratio of the carbon source to the inorganic salt is 1:2.5-1:

5.

5. The method for preparing a zinc-air battery catalyst according to claim 2, wherein: The surfactant is one of PEG and PVA or a mixture of the two, and the mass ratio of the carbon source to the surfactant is 15:1-30:

1.

6. The method for preparing a zinc-air battery catalyst according to claim 2, wherein: The first molybdenum source and the second molybdenum source are both ammonium molybdate.

7. The method for preparing a zinc-air battery catalyst according to claim 2, wherein: The solid-phase pyrolysis adopts a gradient heating method, which includes a first gradient, a second gradient and a third gradient. The temperature of the first gradient is 500°C to 550°C, the holding time is 1h-5h, and the heating rate is 2°C / min to 10°C / min; the temperature of the second gradient is 650°C to 800°C, the holding time is 1h-5h, and the heating rate is 1°C / min to 6°C / min; the third gradient is 850°C to 900°C, the holding time is 1h to 5h, and the heating rate is 1°C / min to 6°C / min.

8. The method for preparing a zinc-air battery catalyst according to claim 2, wherein: The temperature of the hydrothermal reaction is 180° C. to 200° C., and the time of the hydrothermal reaction is 8 hours to 15 hours.

9. The method for preparing a zinc-air battery catalyst according to claim 2, wherein: The conditions of the nitriding treatment are: ammonia atmosphere, a holding temperature of 600° C. to 700° C., a holding time of 4 h to 8 h, and a heating rate of 1° C. / min to 5° C. / min.

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