Cathode catalyst for air cell and method for producing the same

Abstract

The present application relates to a kind of cathode catalyst for air battery and its preparation method, cathode catalyst Cu / Gd-N-C includes: nitrogen-doped porous graphitized carbon carrier, copper atom and gadolinium atom are dispersed in nitrogen-doped porous graphitized carbon carrier at atomic level;Part of copper atom and gadolinium atom respectively form Cu-N x Active site and Gd-N y Active site, another part of copper atom and gadolinium atom is anchored on the framework of nitrogen-doped porous graphitized carbon carrier;Gadolinium atom is controlled by electronic effect Cu-N x Local electronic structure near active site, synergistically improve its oxygen reduction reaction activity and stability;Nitrogen-doped porous graphitized carbon carrier is porous structure for ion transmission.The cathode catalyst of the present application is used in air battery, which can improve the electrochemical activity and cycle performance of air battery.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery materials, in particular to a cathode catalyst for air batteries and a preparation method thereof. BACKGROUND

[0002] With the global consumption of fossil fuels exceeding the reasonable threshold, promoting the transformation of energy structure patterns from traditional forms to new systems has become an important task. At present, electrochemical energy storage systems play a key role in achieving the goal of transforming new energy systems due to their high energy density and excellent durability, but one of the key constraints is the slow kinetics of electrocatalytic oxygen reduction reaction (ORR). Therefore, it is of great significance to develop cathode catalysts with high activity and stability.

[0003] Precious metal materials (Pt, Ag, Au, etc.) have long dominated ORR catalysts due to their excellent catalytic activity. However, their high cost and scarce resource properties have become the core constraints limiting their large-scale application and industrialization, so people have invested a lot of effort to develop non-precious metal electrocatalysts with high intrinsic activity.

[0004] Currently, the preparation of dual active center electrocatalysts through the doping and compounding strategy of rare earth metals and transition metals provides a new research direction for the development of electrocatalysts. Among them, rare earth metal Gd has become one of the research hotspots in the field of ORR electrocatalysis due to its excellent chemical stability and catalytic activity; combining rare earth metal Gd with non-precious metal Cu to regulate the electronic structure of the catalyst is an effective strategy to improve the ORR catalytic activity. Therefore, developing high-performance Cu-Gd catalysts has become one of the research hotspots in the ORR field.

[0005] Currently, there are many methods for preparing Cu-Gd ORR catalysts. However, the materials prepared by existing technologies still face some common problems: on the one hand, the specific surface area of the catalysts is generally limited, resulting in insufficient exposure of active sites; on the other hand, their catalytic activity and stability are still difficult to meet application requirements. In addition, some synthesis methods have limitations such as complex process or poor environmental friendliness.

[0006] In view of the above problems, the present application proposes a new material design and preparation strategy. SUMMARY

[0007] The purpose of the present application is to propose a cathode catalyst for air batteries and a preparation method thereof in view of the problems existing in the prior art.

[0008] The cathode catalyst provided by the application has the characteristics of high specific surface area, high stability and durability, and has micron-level irregular block-shaped particles, a rough surface and nanometer-level small particles with good dispersity, and the overall structure has rich pores, which is beneficial to the adsorption and mass transfer of reactants and can expose more active sites. Meanwhile, the preparation method of the cathode catalyst provided by the application solves the problems of high preparation cost and difficult synthesis control of existing ORR catalysts.

[0009] To achieve the above-mentioned purpose, in a first aspect, the application provides a cathode catalyst for an air cell, denoted as Cu / Gd-N-C, comprising: a nitrogen-doped porous graphitized carbon carrier, copper atoms and gadolinium atoms dispersed in the nitrogen-doped porous graphitized carbon carrier at an atomic level.

[0010] Part of the copper atoms and part of the N atoms in the nitrogen-doped porous graphitized carbon carrier form Cu-N x active sites, wherein x is a positive integer, 2≤x≤4; part of the gadolinium atoms and part of the N atoms in the nitrogen-doped porous graphitized carbon carrier form Gd-N y active sites, y is a positive integer; another part of the copper atoms and gadolinium atoms are dispersed on the framework of the nitrogen-doped porous graphitized carbon carrier in the form of single atoms; the gadolinium atoms regulate the local electronic structure near the Cu-N x active sites through electronic effect, and enhance the oxygen reduction reaction activity and stability of the Cu-N x active sites.

[0011] The nitrogen-doped porous graphitized carbon carrier has a porous structure and is used for ion transmission.

[0012] Preferably, the content of Cu element in the cathode catalyst is 0.2wt%-3.0wt%, and the content of Gd element is 0.1wt%-1.5wt%.

[0013] The specific surface area of the cathode catalyst is 255m 2 / g-305m 2 / g.

[0014] Preferably, the X-ray diffraction analysis spectrum of the cathode catalyst only shows a broad peak of carbon, without metal crystal phase diffraction peaks.

[0015] In a second aspect, the application provides a preparation method of the cathode catalyst of the first aspect.

[0016] In step S1, a zinc source material, a copper source material and a gadolinium source material are dispersed in a first solvent in a certain proportion to obtain a first solution.

[0017] Step S2, dispersing the 2-methyl imidazole with a second solvent, uniformly dispersing to obtain a second solution.

[0018] Step S3, pouring the first solution into the second solution while stirring, stirring until completely mixed, and collecting the precipitate by centrifugation; the precipitate is a metal organic framework material ZIF-8 with co-doping of Cu ions and Gd ions.

[0019] Step S4, washing the precipitate with ethanol several times until neutral, and then drying in an oven to obtain a precursor material.

[0020] Step S5, placing the precursor material in a heat treatment device and performing heat treatment in a protective gas environment to obtain a cathode catalyst Cu / Gd-N-C; during the heat treatment process, a first part of Zn ions in the metal organic framework material ZIF-8 volatilize to form hierarchical pores to obtain the nitrogen-doped porous graphitized carbon carrier, a part of Cu ions and a part of Gd ions dope and replace a second part of Zn ions, and respectively coordinate with N atoms in the nitrogen-doped porous graphitized carbon carrier to form Cu-N x active sites and Gd-N y active sites, another part of Cu ions and a part of Gd ions are anchored on the framework of the nitrogen-doped porous graphitized carbon carrier.

[0021] Preferably, in step S1, the zinc source material is a soluble zinc salt, including one or more of zinc nitrate hydrate, zinc acetate, and zinc chloride.

[0022] The copper source material is a soluble divalent copper salt, including one or more of copper nitrate hydrate, copper acetate, copper chloride, and copper sulfate hydrate.

[0023] The gadolinium source material is a soluble trivalent gadolinium salt, including one or more of gadolinium nitrate hydrate, gadolinium chloride, and gadolinium acetate.

[0024] The molar ratio of Cu in the copper source material to Gd in the gadolinium source material is 3-7:1.

[0025] The first solvent is anhydrous methanol.

[0026] The first dispersion is ultrasonic dispersion.

[0027] Preferably, in step S2, the molar ratio of Zn in the zinc source material to 2-methyl imidazole is 1:3-6.

[0028] The mass ratio of 2-methyl imidazole to the second solvent is 1:19.

[0029] The second solvent is anhydrous methanol.

[0030] The second dispersion is ultrasonic dispersion.

[0031] Preferably, in the step S3, the time of pouring and stirring simultaneously is 12-36 hours.

[0032] Preferably, in the step S4, the drying is vacuum drying, the temperature of vacuum drying is 60-80℃, and the time of vacuum drying is 8-12 hours.

[0033] Preferably, in the step S5, the heat treatment equipment includes any one of a tube furnace or an atmosphere furnace.

[0034] The heat treatment specifically includes: heating to 950-1050℃ at a heating rate of 5-15℃ / min, and holding for 0.5-3 hours.

[0035] In a third aspect, the present application provides an air battery, characterized in that the air battery comprises the cathode catalyst Cu / Gd-N-C of the first aspect, or the cathode catalyst Cu / Gd-N-C prepared by the preparation method of the second aspect; the air battery comprises any one of an aluminum-air battery or a zinc-air battery.

[0036] The present application provides a preparation method of a cathode catalyst for an air battery, and the cathode catalyst, which has the following beneficial effects.

[0037] (1) The present application provides a preparation method of a cathode catalyst, which comprises stirring and mixing a methanol solution containing a zinc source material, a copper source material and a gadolinium source material with a methanol solution containing 2-methylimidazole, centrifuging to collect the precipitate, and then washing and heat treating to obtain a cathode catalyst Cu / Gd-N-C doped with Cu and Gd bimetal; the preparation method is simple to operate, and solves the problems of high preparation cost and difficult synthesis control of existing ORR catalysts.

[0038] (2) The cathode catalyst Cu / Gd-N-C prepared by the preparation method of the present application introduces a rare earth metal element gadolinium (Gd), which can significantly affect the microstructure of the cathode catalyst material, including the crystal lattice structure, the local coordination structure, the defect density, the rearrangement during carbonization, and the pore structure evolution.

[0039] During the preparation of the cathode catalyst Cu / Gd-N-C, gadolinium ions (Gd 3+ ) are doped and substituted for zinc ions (Zn 2+ ), the radius of gadolinium ions is much larger than that of zinc ions, and the valence state is also higher, so it can stretch the framework of Zn-N, introduce stress and distortion.

[0040] Gd can catalyze carbon rearrangement during pyrolysis, promote local graphitization, and cause local disorder of carbon structure and increase defect sites as a large-radius metal ion, and the heterovalent doping of Gd can adjust the local electronic structure of Cu, change the coordination environment of Cu, and induce Cu to form more stable Cu-N x sites, and the electronic density is more suitable for the adsorption / desorption process of the -OOH key reaction intermediate in the ORR process, and a Cu-N x -Gd bimetallic synergistic active center, and the Cu / Gd double-doped system can form an asymmetric metal-nitrogen coordination structure, which can significantly adjust the free energy of the oxygen reduction reaction and enhance the oxygen reduction reaction activity of the cathode catalyst.

[0041] The introduction of Gd changes the carbon framework shrinkage behavior during the Zn volatilization process, so that the formed carbon matrix material has more abundant mesoporous structure, which is beneficial to the rapid transport of reactants and the exposure of more active sites.

[0042] (3) The cathode catalyst Cu / Gd-N-C provided by the application can be used for preparing air batteries, including aluminum-air batteries or zinc-air batteries, and can improve the electrochemical activity and cycle performance of the air batteries. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 is a preparation method flowchart of the cathode catalyst provided by the embodiments of the application.

[0044] Figure 2 is an X-ray diffraction (XRD) spectrum of the cathode catalyst Cu / Gd-N-C provided by embodiment 1 of the application.

[0045] Figure 3 is a scanning electron microscope (SEM) image with a scale of 50 μm of the cathode catalyst Cu / Gd-N-C provided by embodiment 1 of the application.

[0046] Figure 4 is a SEM image with a scale of 300 μm of the cathode catalyst Cu / Gd-N-C provided by embodiment 1 of the application.

[0047] Figure 5 is a BET nitrogen adsorption / desorption curve of the cathode catalyst Cu / Gd-N-C provided by embodiment 1 of the application.

[0048] Figure 6 is a linear sweep voltammetry (LSV) curve of the cathode catalyst Cu / Gd-N-C provided by embodiment 1 of the application and the cathode catalyst Pt / C provided by comparative example 1.

[0049] Figure 7is the specific capacity curve of the aluminum-air battery assembled by the cathode catalyst Cu / Gd-N-C provided in the embodiment 1 of the present application and the cathode catalyst Pt / C provided in the comparative example 1.

[0050] Figure 8 is the cycle discharge stability test curve of the aluminum-air battery assembled by the cathode catalyst Cu / Gd-N-C provided in the embodiment 1 of the present application and the cathode catalyst Pt / C provided in the comparative example 1.

[0051] Figure 9 is the power density curve of the aluminum-air battery assembled by the cathode catalyst Cu / Gd-N-C provided in the embodiment 1 of the present application and the cathode catalyst Pt / C provided in the comparative example 1.

[0052] Figure 10 is the LSV curve after the cyclic voltammetry (CV) test of the cathode catalyst Cu / Gd-N-C provided in the embodiment 1 of the present application for 10000 cycles. DETAILED DESCRIPTION

[0053] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0054] The specific conditions not mentioned in the embodiments are carried out according to the conventional conditions. The reagents or instruments not mentioned by the manufacturers are all the conventional products that can be obtained by market purchase.

[0055] The technical solutions of the present application will be further described in detail below with reference to the drawings and embodiments.

[0056] The embodiment of the present application provides a cathode catalyst for an air battery, which comprises: a nitrogen-doped porous graphitized carbon carrier, copper atoms and gadolinium atoms dispersed in the nitrogen-doped porous graphitized carbon carrier at an atomic level. The cathode catalyst is denoted as Cu / Gd-N-C.

[0057] Part of the copper atoms form Cu-N x active sites, wherein x is an integer of 2-4, for example, one or more of Cu-N2, Cu-N3 and Cu-N4 active sites can be formed; and part of the gadolinium atoms form Gd-N yactive sites, where y is a positive integer, for example, can form one or more of Gd-N6, Gd-N7, Gd-N8, Gd-N9 active sites; another part of the copper atoms and gadolinium atoms are anchored on the framework of the nitrogen-doped porous graphitized carbon carrier; the gadolinium atoms regulate Cu-N x local electronic structure near the active sites, improving Cu-N x active sites oxygen reduction reaction activity and stability.

[0058] The nitrogen-doped porous graphitized carbon carrier is a porous structure for ion transmission. The porous structure can promote the transmission of ions, make the material have a high specific surface area, and can synergistically promote the mass transfer and charge transfer in the oxygen reduction reaction process, which is the key to obtaining high power density and high specific capacity.

[0059] The content of Cu element in the cathode catalyst is 0.2wt%-3.0wt%, which can be any value within the above range, for example, 0.2wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1.0wt%, 1.2wt%, 1.4wt%, 1.6wt%, 1.8wt%, 2.0wt%, 2.2wt%, 2.4wt%, 2.6wt%, 2.8wt%, 3.0wt%, but not limited to the listed values, other values not listed within the value range are also applicable. Cu in the cathode catalyst provides the main active site Cu-N x , the content is too low, the catalytic effect is not obvious, the content is higher, easy to form agglomeration, affect the specific surface area of the cathode catalyst. The content of Cu element in the cathode catalyst is preferably 0.5wt%-2.0wt%.

[0060] The content of Gd element in the cathode catalyst is 0.1wt%-1.5wt%, which can be any value within the above range, for example, 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1.0wt%, 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt%, 1.5wt%, but not limited to the listed values, other values not listed within the value range are also applicable. In the cathode catalyst, a small part of Gd is used to form Gd-N y active sites, most of the gadolinium atoms regulate Cu-N xThe local electronic structure near the active sites, which cooperatively enhances the oxygen reduction reaction activity and stability, and promotes local graphitization. Controlling the content of Gd element is crucial. When the content of Gd element is small, the stabilizing effect on Cu atoms is small; when the content of Gd element is large, Gd2O3 nanoparticles or microparticles are easily formed at high temperature, thereby blocking the channels, shielding the sites, or forming large particle alloys with Cu, reducing the single-atom site density and the specific surface area of the material, and reducing the redox activity. The content of Gd element in the cathode catalyst is preferably 0.3wt%-1.0wt%.

[0061] The specific surface area of the cathode catalyst is 255m 2 / g-305m 2 / g, which can be any value within the above range, for example, 255m 2 / g, 257m 2 / g, 260m 2 / g, 263m 2 / g, 265m 2 / g, 267m 2 / g, 270m 2 / g, 273m 2 / g, 275m 2 / g, 277m 2 / g, 280m 2 / g, 283m 2 / g, 285m 2 / g, 287m 2 / g, 290m 2 / g, 293m 2 / g, 295m 2 / g, 297m 2 / g, 300m 2 / g, 303m 2 / g, 305m 2 / g, etc., but is not limited to the listed values. Other values not listed within this range are also applicable. The specific surface area of the cathode catalyst is preferably 265m 2 / g-295m 2 / g.

[0062] The X-ray diffraction analysis spectrum of the cathode catalyst shows only a broad peak of carbon, and no metal crystal phase diffraction peak, which is one of the key evidences that Cu and Gd exist in the form of atomic dispersion.

[0063] The embodiment of the present application provides a preparation method of a cathode catalyst for an air battery, as shown in Figure 1 , specifically comprising the following steps.

[0064] Step S1, the zinc source material, copper source material and gadolinium source material are dispersed in a first solvent in a certain proportion, uniformly dispersed to obtain a first solution.

[0065] The zinc source material is a soluble zinc salt, including one or more of zinc nitrate hydrate, zinc acetate Zn(CH3COO)2, and zinc chloride (ZnCl2). The zinc nitrate hydrate is preferably zinc nitrate hexahydrate, with a chemical formula of Zn(NO3)2·6H2O.

[0066] The copper source material is a soluble divalent copper salt, including one or more of copper nitrate hydrate, copper acetate Cu(CH3COO)2·H2O, copper chloride (CuCl2), and copper sulfate hydrate. The copper nitrate hydrate can be Cu(NO3)2·5H2O. The copper source material is preferably copper sulfate pentahydrate, with a chemical formula of CuSO4·5H2O.

[0067] The gadolinium source material is a soluble trivalent gadolinium salt, including one or more of gadolinium nitrate hydrate, gadolinium chloride (GdCl3), and gadolinium acetate Gd(CH3COO)3·4H2O. The gadolinium source material is preferably gadolinium nitrate hexahydrate, with a chemical formula of Gd(NO3)3·6H2O.

[0068] The molar ratio of Cu in the copper source material to Gd in the gadolinium source material is 3-7:1, which can be any molar ratio within the above range, such as 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 7:1, but is not limited to the listed values. The molar ratio of Cu in the copper source material to Gd in the gadolinium source material is preferably 5:1.

[0069] The first solvent includes anhydrous methanol.

[0070] The first dispersion is ultrasonic dispersion, with a power of 100-500 W, a time of 10-30 min, and a frequency of 20-80 KHz.

[0071] Step S2, 2-methylimidazole is secondly dispersed in a second solvent, uniformly dispersed to obtain a second solution.

[0072] The molar ratio of Zn in the zinc source material to 2-methylimidazole is 1:3-6, which can be any molar ratio within the above range, such as 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6, but is not limited to the listed values. The molar ratio of Zn in the zinc source material to 2-methylimidazole is preferably 1:4.5.

[0073] The mass ratio of 2-methylimidazole to the second solvent is 1:18-22, preferably 1:19.

[0074] The second solvent is anhydrous methanol.

[0075] The second dispersion is ultrasonic dispersion, the power of the ultrasonic dispersion is 100W-500W, the time is 10min-30min, and the frequency is 20KHz-80KHz.

[0076] Step S3, slowly pour the first solution into the second solution while stirring, stir until completely mixed, and collect the precipitate by centrifugation.

[0077] The total stirring time is 12-36 hours, which can be any value within the above range, for example, 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, 22 hours, 24 hours, 26 hours, 28 hours, 30 hours, 32 hours, 34 hours, 36 hours, etc., but is not limited to the listed values. Other values not listed in this range are also applicable.

[0078] The precipitate is an organic-inorganic hybrid material, and the organic ligand in the organic-inorganic hybrid material is 2-methylimidazole; the precipitate is specifically a metal organic framework material ZIF-8 co-doped with Cu ions and Gd ions.

[0079] Step S4, the precipitate is washed several times with ethanol, and then dried in an oven to obtain a precursor material.

[0080] The precipitate is washed to neutral with ethanol, and the number of washes is at least 3.

[0081] The drying is vacuum drying, the temperature of the vacuum drying is 60-80℃, and the time of the vacuum drying is 8-12 hours.

[0082] Step S5, the precursor material is placed in a heat treatment device and heat treated in a protective gas environment to obtain a cathode catalyst Cu / Gd-N-C.

[0083] The heat treatment device includes any one of a tube furnace or an atmosphere furnace.

[0084] The heat treatment specifically includes heating at a rate of 5-15℃ / min to 950-1050℃, and holding for 0.5-3 hours.

[0085] During the heat treatment process of this step, the first part of Zn ions in the metal organic framework material ZIF-8 volatilizes to form hierarchical pores to obtain a nitrogen-doped porous graphitized carbon carrier, the first part of Cu ions and part of Gd ions doped and substituted the second part of Zn ions, and respectively coordinated with N atoms in the nitrogen-doped porous graphitized carbon carrier to form Cu-N x active sites and Gd-N y active sites, the other part of Cu ions and part of Gd ions are anchored on the framework of the nitrogen-doped porous graphitized carbon carrier.

[0086] The above-mentioned cathode catalyst Cu / Gd-N-C provided by the embodiment of the present application can be applied to an air battery. The air battery includes any one of an aluminum air battery and a zinc air battery. Since the cathode catalyst Cu / Gd-N-C provided by the embodiment of the present application has the characteristics of high specific surface area, high stability and durability, when it is applied to an air battery, the electrochemical activity and cycle performance of the air battery can be improved.

[0087] The air battery provided by the embodiment of the present application can be used in electronic equipment, electric vehicles, large-scale energy storage and emergency power supply.

[0088] In order to better understand the technical solutions provided by the present application, the following describes the preparation process and characteristics of the cathode catalyst provided by the present application with multiple specific examples.

[0089] Embodiment 1

[0090] The embodiment provides a cathode catalyst Cu / Gd-N-C, and the specific preparation process is as follows.

[0091] Step (1) 2g of Zn(NO3)2·6H2O, 0.0174g of CuSO4·5H2O and 0.0063g of Gd(NO3)3·6H2O are placed in an ultrasonic disperser together with 60ml of anhydrous methanol for ultrasonic dispersion for 20min, and a first solution is obtained after uniform dispersion. The molar ratio of Cu in the copper source material to Gd in the gadolinium source material is 5:1.

[0092] Step (2) 2.5g of 2-methylimidazole is placed in an ultrasonic disperser together with 60ml of anhydrous methanol for ultrasonic dispersion, and a second solution is obtained after uniform dispersion. The molar ratio of Zn in the zinc source material to 2-methylimidazole is 1:4.5.

[0093] Step (3) the first solution is slowly poured into the second solution, and a magnetic stirrer is used for stirring during pouring, and the stirring is performed for 24 hours in total. After complete mixing, a precipitate is collected by using a centrifuge.

[0094] Step (4) The precipitate was washed several times with anhydrous ethanol until neutral, and then placed in a vacuum drying oven and dried at 70°C for 8 hours to obtain the precursor material.

[0095] Step (5) The precursor material is placed in a tube furnace and heated to 1000°C at a heating rate of 10°C / min under a nitrogen atmosphere. The temperature is held for 1 hour to obtain the cathode catalyst Cu / Gd-NC.

[0096] The XRD pattern of the cathode catalyst Cu / Gd-NC prepared in this embodiment is shown below. Figure 2 As shown, the horizontal axis represents the diffraction angle 2θ (unit: °), and the vertical axis represents the diffraction intensity (unit: au). Figure 2 As can be seen, the XRD diffraction peaks only show broad peaks for carbon, with no metallic phase peaks, proving that Cu and Gd are dispersed at the atomic level (e.g., Cu-N). x It is anchored in a carbon carrier in the form of a physical mixture, rather than forming an alloy or nanoparticle.

[0097] The cathode catalyst Cu / Gd-NC prepared in this embodiment is shown in the SEM image with a scale bar of 50 μm, as follows. Figure 3 As shown, the cathode catalyst Cu / Gd-NC is in the form of micron-sized irregular blocky particles with a rough surface and well-dispersed nano-sized fine particles, and the overall structure has abundant pores.

[0098] The SEM image of the Cu / Gd-NC cathode catalyst prepared in this embodiment, with a scale bar of 300 μm, is shown below. Figure 4 As shown.

[0099] The specific surface area of ​​the Cu / Gd-NC cathode catalyst prepared in Example 1 was determined using the Brunauer-Emmet-Teller (BET) gas adsorption method. The BET nitrogen adsorption-desorption curves are shown below. Figure 5 As shown, the horizontal axis represents relative pressure, and the vertical axis represents adsorption capacity (unit: cm). 3 / g), the adsorption amount is expressed by volume under standard conditions (STP). The specific surface area of ​​the cathode catalyst Cu / Gd-NC prepared in Example 1 was tested to be 279.985 m². 2 / g. Figure 5 The inset shows the corresponding porosity distribution, with the horizontal axis representing pore size (nm) and the vertical axis representing the differential distribution of pore volume (cm). 3 The pore size is mainly distributed between 5 and 20 nm, which falls within the mesoporous range, indicating that this catalyst has typical mesoporous structural characteristics. The specific surface area and pore size analyzer was a Micromeritics 3-Flex from McMuritics (Shanghai) Instruments Co., Ltd., USA.

[0100] The aluminum-air battery was assembled and tested using the Cu / Gd-NC cathode catalyst prepared in this embodiment, as detailed below.

[0101] The assembly process of the aluminum-air battery is as follows: A polished aluminum sheet (99.99% purity) is used as the metal anode; 5 mg of the cathode catalyst prepared in this example is added to 1 mL of anhydrous ethanol dispersion containing 30 μL of Nafion solution (0.5 wt%), and after ultrasonic dispersion, a uniform ink-like liquid is formed; this ink-like liquid is uniformly drop-coated onto carbon paper to obtain an air electrode with a cathode catalyst loading of 1 mg / cm². The aluminum-air battery is assembled using conventional assembly processes, and the electrolyte is a 4 mol / L NaOH solution (deionized water as the solvent).

[0102] The electrochemical performance of the cathode catalyst in this embodiment was tested using a CHI760E electrochemical workstation. The specific method was as follows: the preparation method of the ink-like liquid was the same as the aluminum-air battery assembly process described above. The liquid was dropped onto a rotating ring-disk electrode (0.2475 cm⁻¹). 2 After drying, the cathode catalyst loading was found to be 0.255 mg / cm³. 2 The working electrode was determined using the PINE rotating ring-disc electrode system from the United States. A graphite rod was used as the auxiliary electrode (counter electrode), and a saturated calomel electrode (Hg / Hg2Cl2) was used as the reference electrode. The test was conducted in a KOH electrolyte with a molar concentration of 0.1 mol / L (deionized water as the solvent).

[0103] The assembled aluminum-air battery was also tested using a CHI760E electrochemical workstation: the discharge polarization curve of the battery was tested at a scan rate of 1 mV / s, and the power density of the battery was calculated based on the curve.

[0104] The cyclic charge-discharge stability of the aluminum-air battery assembled in this embodiment was tested using the Blue Lightning testing system: the cyclic charge-discharge stability test was conducted at 20 mA / cm. 2 The test was conducted at a current density for one hour, followed by a 20-minute rest period. The specific capacity of the aluminum-air battery was calculated based on the mass of aluminum sheet consumed.

[0105] The linear sweep voltammetry (LSV) curve of the cathode catalyst Cu / Gd-NC prepared in Example 1 is as follows: Figure 6 As shown, the horizontal axis represents the electrode potential (unit: V), and the vertical axis represents the current density (unit: mA / cm²). 2 ).

[0106] The specific capacity curve of the aluminum-air battery assembled with the cathode catalyst Cu / Gd-NC prepared in Example 1 is as follows: Figure 7The horizontal axis is the specific capacity (unit: mAh / g), and the vertical axis is the voltage (unit: V).

[0107] The cycle discharge stability test curve of the aluminum-air battery assembled by the cathode catalyst Cu / Gd-N-C prepared in this embodiment 1 is shown in Figure 8 The horizontal axis is the time (unit: hour), and the vertical axis is the voltage (unit: V).

[0108] The power density curve of the aluminum-air battery assembled by the cathode catalyst Cu / Gd-N-C prepared in this embodiment 1 is shown in Figure 9 The horizontal axis is the current density (unit: mA / cm 2 ), the left vertical axis is the voltage (unit: V), and the right vertical axis is the power density (unit: mW / cm 2 ).

[0109] The LSV curve of the cathode catalyst Cu / Gd-N-C prepared in this embodiment 1 after 10,000 cycles of CV is shown in Figure 10 The horizontal axis is the electrode potential (unit: V, relative to the reversible hydrogen electrode RHE), and the vertical axis is the current density (unit: mA / cm 2 ). Figure 10 It can be seen that after 10,000 cycles of accelerated aging, the half-wave potential of the cathode catalyst Cu / Gd-N-C prepared in this embodiment changes from 0.74 V to 0.73 V, only decreasing by 0.1 V, indicating that the cathode catalyst Cu / Gd-N-C provided in this embodiment has extremely high electrochemical structural stability and excellent durability.

[0110] Embodiment 2

[0111] The embodiment provides a cathode catalyst Cu / Gd-N-C, and the specific preparation process is as follows.

[0112] Step (1) Put 1.24 g of Zn(CH3COO)2, 0.014 g of Cu(CH3COO)2·H2O and 0.0057 g of Gd(CH3COO)3·4H2O into an ultrasonic disperser together with 60 ml of anhydrous methanol for ultrasonic dispersion, and uniformly disperse to obtain a first solution. The molar ratio of Cu in the copper source material to Gd in the gadolinium source material is 5:1.

[0113] Step (2) Put 2.5 g of 2-methylimidazole into an ultrasonic disperser together with 60 ml of anhydrous methanol for ultrasonic dispersion for 20 min, and uniformly disperse to obtain a second solution. The molar ratio of Zn in the zinc source material to 2-methylimidazole is 1:4.5.

[0114] Step (3) slowly pour the first solution into the second solution, stirring with a magnetic stirrer while pouring, and stir for a total of 24 hours until completely mixed, then use a centrifuge to collect the precipitate.

[0115] Step (4) wash the precipitate with anhydrous ethanol several times until it is neutral, then place it in a vacuum drying oven at 60°C for 12 hours to obtain a precursor material.

[0116] Step (5) place the precursor material in a tube furnace, heat to 950°C at a rate of 5°C / min under a nitrogen gas environment, and hold for 2 hours to obtain a cathode catalyst Cu / Gd-N-C.

[0117] Test the specific surface area of the cathode catalyst Cu / Gd-N-C prepared in this example, the test method is the same as in Example 1, and the test data are shown in Table 1.

[0118] Assemble an aluminum-air battery using the cathode catalyst Cu / Gd-N-C prepared in this example and perform electrochemical performance testing, the battery assembly method and testing method are the same as in Example 1, and the test data are shown in Table 1.

[0119] Example 3

[0120] This example provides a cathode catalyst Cu / Gd-N-C, and the specific preparation process is as follows.

[0121] Step (1) place 2g of Zn(NO3)2·6H2O, 0.0174g of CuSO4·5H2O, and 0.0105g of Gd(NO3)3·6H2O in an ultrasonic disperser with 60ml of anhydrous methanol to perform ultrasonic dispersion, and disperse uniformly to obtain a first solution. The molar ratio of Cu in the copper source material to Gd in the gadolinium source material is 3:1.

[0122] Step (2) place 2.5g of 2-methylimidazole in an ultrasonic disperser with 60ml of anhydrous methanol and perform ultrasonic dispersion for 30 minutes, and disperse uniformly to obtain a second solution. The molar ratio of Zn in the zinc source material to 2-methylimidazole is 1:4.5.

[0123] Step (3) slowly pour the first solution into the second solution, stirring with a magnetic stirrer while pouring, and stir for a total of 24 hours until completely mixed, then use a centrifuge to collect the precipitate.

[0124] Step (4) wash the precipitate with anhydrous ethanol several times until it is neutral, then place it in a vacuum drying oven at 60°C for 12 hours to obtain a precursor material.

[0125] Step (5) The precursor material was placed in a tube furnace, heated to 950℃ at a heating rate of 5℃ / min under nitrogen gas environment, and kept for 2 hours to obtain the cathode catalyst Cu / Gd-N-C.

[0126] The specific surface area of the cathode catalyst Cu / Gd-N-C prepared in this example was tested, and the test method was the same as that in Example 1. The test data are shown in Table 1.

[0127] The aluminum-air battery was assembled using the cathode catalyst Cu / Gd-N-C prepared in this example, and the electrochemical performance test was carried out. The battery assembly method and the test method were the same as those in Example 1. The test data are shown in Table 1.

[0128] Example 4

[0129] This example provides a cathode catalyst Cu / Gd-N-C, and the specific preparation process is as follows.

[0130] Step (1) 2g of Zn(NO3)2·6H2O, 0.0174g of Cu(NO3)2·5H2O and 0.0045g of Gd(NO3)3·6H2O were placed in an ultrasonic disperser together with 60ml of anhydrous methanol for ultrasonic dispersion. After uniform dispersion, a first solution was obtained. The molar ratio of Cu in the copper source material to Gd in the gadolinium source material was 7:1.

[0131] Step (2) 2.5g of 2-methylimidazole was placed in an ultrasonic disperser together with 60ml of anhydrous methanol for ultrasonic dispersion for 30min. After uniform dispersion, a second solution was obtained. The molar ratio of Zn in the zinc source material to 2-methylimidazole was 1:4.5.

[0132] Step (3) The first solution was slowly poured into the second solution, and a magnetic stirrer was used for stirring during pouring. The stirring was carried out for 24 hours until complete mixing. Then a centrifuge was used to collect the precipitate.

[0133] Step (4) The precipitate was washed with anhydrous ethanol several times until it was neutral. Then it was placed in a vacuum drying oven at 70℃ for vacuum drying for 10 hours to obtain a precursor material.

[0134] Step (5) The precursor material was placed in a tube furnace, heated to 950℃ at a heating rate of 5℃ / min under nitrogen gas environment, and kept for 2 hours to obtain the cathode catalyst Cu / Gd-N-C.

[0135] The specific surface area of the cathode catalyst Cu / Gd-N-C prepared in this example was tested, and the test method was the same as that in Example 1. The test data are shown in Table 1.

[0136] The cathode catalyst Cu / Gd-N-C prepared in the example was used to assemble an aluminum-air battery, and electrochemical performance test was carried out. The battery assembly method and the test method were the same as those in example 1. The test data are shown in Table 1.

[0137] Example 5

[0138] The example provides a cathode catalyst Cu / Gd-N-C. The specific preparation process is as follows.

[0139] Step (1) 2g of Zn(NO3)2·6H2O, 0.0174g of CuSO4·5H2O and 0.0063g of Gd(NO3)3·6H2O were placed in an ultrasonic disperser with 60ml of anhydrous methanol for ultrasonic dispersion for 20min. After uniform dispersion, a first solution was obtained. The molar ratio of Cu in the copper source material to Gd in the gadolinium source material was 5:1.

[0140] Step (2) 1.66g of 2-methylimidazole was placed in an ultrasonic disperser with 60ml of anhydrous methanol for ultrasonic dispersion. After uniform dispersion, a second solution was obtained. The molar ratio of Zn in the zinc source material to 2-methylimidazole was 1:3.

[0141] Step (3) The first solution was slowly poured into the second solution, and a magnetic stirrer was used for stirring during pouring. The stirring was performed for 24 hours until complete mixing. Then, a centrifuge was used to collect the precipitate.

[0142] Step (4) The precipitate was washed with anhydrous ethanol several times until it was neutral. Then, it was placed in a vacuum drying oven at 70℃ for 8 hours to obtain a precursor material.

[0143] Step (5) The precursor material was placed in a tube furnace, and heated to 1000℃ at a heating rate of 10℃ / min under a nitrogen gas environment. After 1 hour of heat preservation, a cathode catalyst Cu / Gd-N-C was obtained.

[0144] The specific surface area of the cathode catalyst Cu / Gd-N-C prepared in the example was tested. The test method was the same as that in example 1. The test data are shown in Table 1.

[0145] The cathode catalyst Cu / Gd-N-C prepared in the example was used to assemble an aluminum-air battery, and electrochemical performance test was carried out. The battery assembly method and the test method were the same as those in example 1. The test data are shown in Table 1.

[0146] Example 6

[0147] The example provides a cathode catalyst Cu / Gd-N-C. The specific preparation process is as follows.

[0148] Step (1) 2 g of Zn (NO3) 2·6H2O, 0.0174 g of CuSO4·5H2O and 0.0063 g of Gd (NO3) 3·6H2O were placed in an ultrasonic disperser with 60 ml of anhydrous methanol and ultrasonically dispersed for 20 min to obtain a first solution. The molar ratio of Cu in the copper source material to Gd in the gadolinium source material was 5:1.

[0149] Step (2) 3.31 g of 2-methylimidazole was placed in an ultrasonic disperser with 60 ml of anhydrous methanol and ultrasonically dispersed to obtain a second solution. The molar ratio of Zn in the zinc source material to 2-methylimidazole was 1:6.

[0150] Step (3) The first solution was slowly poured into the second solution while stirring with a magnetic stirrer, and the stirring was continued for 24 h until complete mixing. The precipitate was then collected using a centrifuge.

[0151] Step (4) The precipitate was washed with anhydrous ethanol several times until it was neutral, and then placed in a vacuum drying oven at 70°C for 8 h to obtain a precursor material.

[0152] Step (5) The precursor material was placed in a tube furnace and heated to 1000°C at a heating rate of 10°C / min under a nitrogen gas environment, and held for 1 h to obtain a cathode catalyst Cu / Gd-N-C.

[0153] The specific surface area of the cathode catalyst Cu / Gd-N-C prepared in this example was tested, and the testing method was the same as that in Example 1. The test data are shown in Table 1.

[0154] An aluminum-air battery was assembled using the cathode catalyst Cu / Gd-N-C prepared in this example, and the electrochemical performance was tested. The battery assembly method and the testing method were the same as those in Example 1. The test data are shown in Table 1.

[0155] To better illustrate the effect of the example of the present application, the following comparative examples are compared with the above examples.

[0156] Comparative Example 1

[0157] A commercial cathode catalyst Pt / C was used as a comparative example. The specific surface area of the commercial cathode catalyst Pt / C was tested by BET nitrogen adsorption-desorption curve, and the specific surface area was 200 m 2 / g. The specific surface area of the Cu / Gd-N-C prepared in Example 1 was about 28% higher than that of the Pt / C. The specific type of the cathode catalyst Pt / C in this comparative example was 20% Pt / Vulcan XC-72, which represented a carbon-supported catalyst Vulcan XC-72 with a platinum content of 20%, and the brand was Premetek.

[0158] An aluminum-air battery was assembled using the Pt / C cathode catalyst. The battery assembly and testing processes were the same as in Example 1.

[0159] The linear sweep voltammetry (LSV) curve of the cathode catalyst Pt / C provided in Comparative Example 1 is shown below. Figure 6 As shown, through Figure 6 It can be seen that the cathode catalyst (Pt / C) of Comparative Example 1 has a higher onset potential and half-wave potential (0.85V), which reflects the excellent intrinsic oxygen reduction activity of the noble metal Pt. The half-wave potential of the cathode catalyst (Cu / Gd-NC) of Example 1 is 0.74V; however, the limiting current density of the cathode catalyst Cu / Gd-NC provided in Example 1 can reach 8.33 mA / cm². 2 This is significantly higher than the limiting current density of 4.96 mA / cm² in Comparative Example 1. 2 This indicates that the cathode catalyst Cu / Gd-NC provided in Example 1 has a higher active site density and better mass transfer capability.

[0160] The specific capacity curve of the aluminum-air battery assembled with the Pt / C cathode catalyst provided in Comparative Example 1 is as follows: Figure 7 As shown, Figure 7 The corresponding discharge specific capacity curves are shown. The discharge specific capacity of Comparative Example 1 is 268.58 mAh / g, while the discharge specific capacity of Example 1 is 607.29 mAh / g, which is much higher than that of Comparative Example 1. This indicates that the cathode catalyst Cu / Gd-NC provided in Example 1 can significantly improve the energy output of aluminum-air batteries.

[0161] The cycle discharge stability test curve of the aluminum-air battery assembled with the Pt / C cathode catalyst provided in Comparative Example 1 is as follows: Figure 8 As shown, through Figure 8 As can be seen, the aluminum-air battery of Example 1 operated stably for approximately 11 hours during the test, while the aluminum-air battery of Comparative Example 1 failed after only about 8 hours. This indicates that the cathode catalyst Cu / Gd-NC provided in Example 1 of this invention has superior electrochemical stability and durability.

[0162] The power density curve of the aluminum-air battery assembled with the Pt / C cathode catalyst provided in Comparative Example 1 is shown below. Figure 9 As shown, through Figure 8 As can be seen, the aluminum-air battery in Example 1 operates at a current density of 97.56 mA / cm². 2 It reaches a peak power density of 60.1 mW / cm³. 2 In contrast, the peak power density of the aluminum-air battery in Comparative Example 1 was only 54.11 mW / cm³. 2 (Corresponding current density 86.58 mA / cm)2 ), which indicates that the cathode catalyst Pt / C provided by the embodiment 1 of the present application allows the battery to work at a higher current while maintaining a high power output.

[0163] Comparative Example 2

[0164] The present comparative example provides a process for preparing a cathode catalyst Cu / Gd-N-C, which is different from the embodiment 1 in that in step (1), the molar ratio of Cu in the copper source material to Gd in the gadolinium source material is 1:1, that is, 2 g of Zn(NO3)2·6H2O, 0.0174 g of CuSO4·5H2O and 0.0315 g of Gd(NO3)3·6H2O are placed in an ultrasonic disperser with 60 ml of anhydrous methanol to perform ultrasonic dispersion for 20 min, and a first solution is obtained after uniform dispersion.

[0165] The other preparation processes are the same as those in the embodiment 1.

[0166] The specific surface area of the cathode catalyst Cu / Gd-N-C prepared in the present comparative example is tested, and the testing method is the same as that in the embodiment 1, and the testing data are shown in Table 1.

[0167] The aluminum-air battery is assembled using the cathode catalyst Cu / Gd-N-C prepared in the present comparative example, and the electrochemical performance test is performed, and the battery assembly method and the testing method are the same as those in the embodiment 1, and the testing data are shown in Table 1.

[0168] Comparative Example 3

[0169] The present comparative example provides a process for preparing a cathode catalyst Cu / Gd-N-C, which is different from the embodiment 1 in that in step (1), the molar ratio of Cu in the copper source material to Gd in the gadolinium source material is 8:1, that is, 2 g of Zn(NO3)2·6H2O, 0.0174 g of Cu(NO3)2·5H2O and 0.0039 g of Gd(NO3)3·6H2O are placed in an ultrasonic disperser with 60 ml of anhydrous methanol to perform ultrasonic dispersion for 20 min, and a first solution is obtained after uniform dispersion.

[0170] The other preparation processes are the same as those in the embodiment 1.

[0171] The specific surface area of the cathode catalyst Cu / Gd-N-C prepared in the present comparative example is tested, and the testing method is the same as that in the embodiment 1, and the testing data are shown in Table 1.

[0172] The aluminum-air battery is assembled using the cathode catalyst Cu / Gd-N-C prepared in the present comparative example, and the electrochemical performance test is performed, and the battery assembly method and the testing method are the same as those in the embodiment 1, and the testing data are shown in Table 1.

[0173] Comparative Example 4

[0174] The comparative example provides a process for preparing a cathode catalyst Cu / Gd-N-C, which is different from example 1 in that the molar ratio of Zn in Zn(NO3)2·6H2O to 2-methylimidazole is 1:2, and the other preparation processes are the same as example 1.

[0175] The specific surface area of the cathode catalyst Cu / Gd-N-C prepared in the comparative example is tested, and the testing method is the same as example 1. The test data are shown in Table 1.

[0176] The aluminum-air battery is assembled using the cathode catalyst Cu / Gd-N-C prepared in the comparative example, and the electrochemical performance test is carried out. The battery assembly method and the testing method are the same as example 1. The test data are shown in Table 1.

[0177] Comparative example 5

[0178] The comparative example provides a process for preparing a cathode catalyst Cu / Gd-N-C, which is different from example 1 in that the molar ratio of Zn in Zn(NO3)2·6H2O to 2-methylimidazole is 1:7, and the other preparation processes are the same as example 1.

[0179] The specific surface area of the cathode catalyst Cu / Gd-N-C prepared in the comparative example is tested, and the testing method is the same as example 1. The test data are shown in Table 1.

[0180] The aluminum-air battery is assembled using the cathode catalyst Cu / Gd-N-C prepared in the comparative example, and the electrochemical performance test is carried out. The battery assembly method and the testing method are the same as example 1. The test data are shown in Table 1.

[0181] Table 1 is a summary of the test data of the catalysts and the assembled aluminum-air batteries of examples 1-6 and comparative examples 1-5:

[0182]

[0183] From the test data in Table 1, it can be seen that the specific surface area of the cathode catalysts of examples 1-6 is higher than that of comparative examples 1-4, and the discharge specific capacity and the limiting current density of the aluminum-air batteries of examples 1-6 are higher than those of comparative examples 1-5.

[0184] Comparative Example 1 (commercial Pt / C) has an advantage in intrinsic oxygen reduction activity (half-wave potential), but the cathode catalyst of Example 1 (Cu / Gd-N-C) achieves overall outperformance in key indicators determining the actual performance of the battery: the limiting current density of Example 1 is 68% higher, the specific discharge capacity is 126% higher, the peak power density is 11% higher, and the cycle stability (operation time) is 38% longer than those of Comparative Example 1. This fully proves that, by constructing an atomic-level dispersed Cu / Gd-N-C catalytic structure, the present application successfully realizes the unification of high active site density, fast mass transfer and excellent stability on a non-noble metal catalyst, and finally translates into significant improvement in the comprehensive performance of the aluminum-air battery, which has great potential to replace noble metal catalysts.

[0185] In Comparative Example 2, the molar ratio of Cu in the copper source material to Gd in the gadolinium source material is set to 1:1, and the gadolinium content is too high. As shown in the data in Table 1, the performance of the cathode catalyst of Comparative Example 2 systematically declines: the specific surface area decreases to 248.67 m 2 / g, the half-wave potential decreases to 0.69 V, and the limiting current density and specific discharge capacity of the assembled aluminum-air battery also decrease significantly. This shows that the excessive gadolinium of Comparative Example 1 cannot be effectively doped, but instead forms inert Gd2O3 nanoparticles during pyrolysis, resulting in blockage of the carrier pores, shielding and dilution of the active sites. This fully shows that the present application controls the Cu / Gd molar ratio in the range of 3:1 to 7:1, which is the key to avoiding the above structural degradation and obtaining a high-performance cathode catalyst.

[0186] In Comparative Example 3, the molar ratio of Cu in the copper source material to Gd in the gadolinium source material is set to 8:1, and the gadolinium content is too low. As shown in the data in Table 1, the performance of the cathode catalyst of Comparative Example 3 declines significantly: the specific surface area decreases to 253.29 m 2 / g; the half-wave potential decreases to 0.70 V; and the limiting current density and specific discharge capacity also decrease synchronously. This shows that when the gadolinium content is insufficient, its electronic regulation and dispersion stabilization effect on Cu are ineffective, resulting in agglomeration of Cu-N x active sites and insufficient development of carbon carrier pores. This fully shows that the present application controls the Cu / Gd molar ratio in the range of 3:1 to 7:1, which is the key to avoiding active site instability and ensuring the comprehensive performance of the catalyst.

[0187] In Comparative Example 4, the molar ratio of Zn in Zn(NO3)2·6H2O to 2-methylimidazole is set to 1:2, and the zinc content is relatively high compared to the ligand ratio. As shown in the data in Table 1, the performance of the catalyst declines significantly: the specific surface area decreases to 236.85 m 2 / g; the half-wave potential is as low as 0.68 V; and the limiting current density and specific discharge capacity both decrease significantly. This shows that when the zinc source ratio is too high, the 2-methylimidazole ligand is insufficient, and cannot fully coordinate with Zn2+ Zn 2+ Gd 3+ The stable metal organic framework (MOF) precursor is formed, and the carbon carrier has poor pore development after calcination, and the excessive Zn pyrolysis residue is easy to block the pore and destroy the active site dispersion. This fully shows that the reasonable molar ratio of Zn in the zinc source material to the ligand 2-methyl imidazole is the key to guarantee the pore structure and catalytic performance of the catalyst.

[0188] In the comparative example 5, the molar ratio of Zn in Zn(NO3)2·6H2O to 2-methyl imidazole is set to 1:7, and the relative ratio of zinc content to ligand is too low. As shown in the data in Table 1, the cathode catalyst performance of the comparative example 5 is obviously degraded: the specific surface area is reduced to 262.43 m 2 / g; the half-wave potential is as low as 0.69 V; and the limiting current density and the specific discharge capacity are both synchronously reduced. This shows that when the zinc source ratio is too low, the 2-methyl imidazole ligand is excessive, which leads to the intensified coordination competition of metal ions (Zn 2+ Zn 2+ Gd 3+ ), and the uniform MOF precursor cannot be formed. After calcination, the carbon carrier structure is loose, the active site density is reduced, and the excessive ligand pyrolysis is easy to produce amorphous carbon to block the pore. This fully shows that the reasonable molar ratio of Zn in the zinc source material to the ligand 2-methyl imidazole is the key to guarantee the structural integrity and catalytic activity of the catalyst.

[0189] The above specific embodiments further specifically describe the purposes, technical solutions, and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A cathode catalyst for an air cell, characterized by, The cathode catalyst represented as Cu / Gd-N-C comprises: a nitrogen-doped porous graphitized carbon carrier, copper atoms and gadolinium atoms dispersed at an atomic level in the nitrogen-doped porous graphitized carbon carrier; wherein part of the copper atoms form Cu-N with part of the N atoms in the nitrogen-doped porous graphitized carbon support x active sites, wherein x is a positive integer, 2≤x≤4; part of the gadolinium atoms form Gd-N with part of the N atoms in the nitrogen-doped porous graphitized carbon support y active sites, y is a positive integer; another part of the copper atoms and the gadolinium atoms are dispersed in a monatomic form on the framework of the nitrogen-doped porous graphitized carbon support; the gadolinium atoms regulate the Cu-N through an electronic effect x local electronic structure near the active sites, which enhances the Cu-N x oxygen reduction reaction activity and stability of the active sites; The nitrogen-doped porous graphitized carbon carrier is a porous structure for ion transmission; The cathode catalyst is obtained by stirring and mixing a methanol solution containing a zinc source material, a copper source material and a gadolinium source material with a methanol solution containing 2-methyl imidazole, centrifuging to collect the precipitate, washing and then performing heat treatment; The molar ratio of Cu in the copper source material to Gd in the gadolinium source material is 3-7:1; The molar ratio of Zn in the zinc source material to 2-methyl imidazole is 1:3-6; The heat treatment comprises: heating at a temperature increasing rate of 5-15 ℃ / min to 950-1050 ℃, and holding for 0.5-3 hours.

2. The cathode catalyst of claim 1, wherein The content of Cu element in the cathode catalyst is 0.2-3.0 wt%, and the content of Gd element is 0.1-1.5 wt%; The specific surface area of the cathode catalyst is 255 m 2 / g to 305 m 2 / g.

3. The cathode catalyst of claim 1, wherein The X-ray diffraction analysis spectrum of the cathode catalyst only shows a broad peak of carbon, without metal crystal phase diffraction peaks.

4. A method of producing the cathode catalyst as claimed in any one of claims 1 to 3, characterized by The preparation method comprises: Step S1, dispersing a zinc source material, a copper source material and a gadolinium source material in anhydrous methanol according to a certain proportion to obtain a first solution; Step S2, dispersing 2-methyl imidazole in anhydrous methanol to obtain a second solution; Step S3, pouring the first solution into the second solution while stirring, stirring until completely mixed, and centrifuging to collect the precipitate; the precipitate is a metal organic framework material ZIF-8 with co-doping of Cu ions and Gd ions; Step S4, washing the precipitate with ethanol several times until neutral, and then drying in an oven to obtain a precursor material; Step S5, the precursor material is placed in a heat treatment device and subjected to heat treatment in a protective gas environment to obtain a cathode catalyst Cu / Gd-N-C; in the heat treatment process, a first part of Zn ions in the metal organic framework material ZIF-8 volatilize to form hierarchical pores to obtain the nitrogen-doped porous graphitized carbon carrier, a part of Cu ions and a part of Gd ions doped and substituted into a second part of Zn ions, and respectively coordinated with N atoms in the nitrogen-doped porous graphitized carbon carrier to form Cu-N x active sites and Gd-N y active sites, another part of Cu ions and a part of Gd ions are anchored on the framework of the nitrogen-doped porous graphitized carbon carrier.

5. The production method according to claim 4, characterized by, In step S1, the zinc source material is a soluble zinc salt, including one or more of zinc nitrate hydrate, zinc acetate and zinc chloride; The copper source material is a soluble divalent copper salt, including one or more of copper nitrate hydrate, copper acetate, copper chloride and copper sulfate hydrate; The gadolinium source material is a soluble trivalent gadolinium salt, including one or more of gadolinium nitrate hydrate, gadolinium chloride and gadolinium acetate; The molar ratio of Cu in the copper source material to Gd in the gadolinium source material is 3-7:1; The first dispersion is ultrasonic dispersion.

6. The preparation method according to claim 4, characterized in that, In step S2, the molar ratio of Zn in the zinc source material to 2-methyl imidazole is 1:3-6; The mass ratio of 2-methyl imidazole to the second solvent is 1:19; The second dispersion is ultrasonic dispersion.

7. The preparation method according to claim 4, characterized in that, In step S3, the stirring time is 12-36 hours.

8. The preparation method according to claim 4, characterized in that, In step S4, the drying is vacuum drying, the temperature of vacuum drying is 60-80 ℃, and the time of vacuum drying is 8-12 hours.

9. The method of claim 4, wherein, In step S5, the heat treatment equipment includes any one of a tube furnace or an atmosphere furnace. The heat treatment specifically comprises: heating to 950-1050 DEG C at a heating rate of 5-15 DEG C / min, and holding for 0.5-3 hours.

10. An air cell characterized by comprising: The air battery comprises the cathode catalyst Cu / Gd-N-C according to any one of claims 1-3, or the cathode catalyst Cu / Gd-N-C prepared by the preparation method according to any one of claims 4-9; and the air battery comprises any one of an aluminum air battery and a zinc air battery.

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