CN111640953A - Air electrode catalyst of aluminum-air battery and preparation method thereof - Google Patents

Abstract

The invention discloses a nano-perovskite air electrode catalyst for an aluminum-air battery and a preparation method thereof. Belonging to the technical field of aluminum-air battery preparation, the present invention uses a sol-gel method for the perovskite catalyst with larger particle size, smaller specific surface area and less morphological characteristics prepared by the existing preparation method. Synthesis of perovskite catalyst La _0.4 S _r0.6 Co _0.7 Fe _0.2 Nb _0.1 O ₃ , the catalyst has small particle size, uniform size, large specific surface area, good repeatability, high catalytic activity, stable physical and chemical properties, pharmaceutical It has the advantages of being cheap and easy to obtain, low temperature required for material preparation, short time, low cost of raw materials, environment-friendly preparation process, and easy industrial production. La _0.4 S _r0.6 Co _0.7 Fe _0.2 Nb _0.1 O ₃ can be used as an air electrode catalyst for aluminum-air batteries. The aluminum-air battery prepared by the method has the advantages of high discharge voltage and good stability. The preparation process provided by the invention is simple and easy to control, and is favorable for large-scale batch production.

Description

A kind of air electrode catalyst of aluminum-air battery and preparation method thereof

technical field

The invention belongs to the technical field of aluminum-air battery preparation, and particularly relates to an air electrode catalyst of an aluminum-air battery and a preparation method thereof.

Background technique

Modern society is currently in the transition stage from a fossil fuel-based economy to the clean energy needed to reduce environmental pollution. Therefore, some renewable energy sources are being developed, such as solar, wind and hydroelectric power. Among these novel energy storage systems, metal-air batteries have attracted much attention due to their high energy density, large capacity, low cost (depending on the metal anode), and constant discharge voltage. However, oxygen reduction reactions are kinetically sluggish, which requires additional energy (overpotential) to overcome the kinetic barriers of these reactions, and the energy efficiency of these devices is greatly reduced, limiting the commercialization of these energy devices. Therefore, it is necessary to develop electrocatalysts to facilitate such reactions, thereby reducing the additional energy required to drive these reactions in these devices.

At present, noble metal platinum (Pt) is considered to be the best electrocatalyst for oxygen reduction reaction in alkaline oxygen electrocatalysis, but its commercial application development is severely limited due to its high price and single catalytic performance. The development of non-precious metal catalysts has become the focus of metal-air batteries. So far, many types of non-noble metal catalysts, such as metal macrocycles and carbonaceous materials, transition metal oxides in perovskite form, spinels and their dopants have been reported. Among various bifunctional catalysts, perovskite-based oxides have been used as oxygen catalysts due to their good catalytic activity and stability in alkaline solutions. Due to the enormous flexibility of perovskite in composition and crystal structure, perovskite oxides have tunable electronic structures, and their physicochemical properties can be widely altered, which can further tune their catalytic activities. It has various physical and chemical properties. In addition, perovskites show great potential for catalysis of oxygen reduction reactions, oxygen evolution reactions, and hydrogen evolution reactions. Because of their easy synthesis, relatively low cost, flexible structure, and high intrinsic catalytic activity, they are expected to become a variety of energy-related applications. efficient electrocatalysts.

Traditional synthesis methods of perovskite catalysts (for example, solid-phase synthesis, molten salt method, and co-precipitation method) usually can only obtain perovskite catalysts with larger particle size, small specific surface area and less morphological features, and the catalytic activity limited, limiting its large-scale practical applications (eg, metal-air batteries, water electrolysis, solid oxide fuel cells). Synthesis of nano-scale perovskites is an effective way to improve catalytic performance, which is closely related to the nano-size effect. With the reduction of nano-perovskite particle size, its surface area increases and catalytic active sites increase, thereby improving catalytic performance. .

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide an aluminum-air battery air electrode catalyst with low raw material price, high catalytic activity and good chemical stability in view of the problems existing in the existing aluminum-air battery. The aluminum-air battery air electrode catalyst The molecular formula is La _0.4 S _r0.6 Co _0.7 Fe _0.2 Nb _0.1 O ₃ , which is formed by the aggregation of perovskite structure particles with an average particle size of 100 nm to form a loose and porous morphology.

Another object of the present invention is to provide a preparation method for the above-mentioned aluminum-air battery air electrode catalyst. The preparation method adopts a sol-gel method to prepare a metal oxide powder with fine particles and a large specific surface area.

The object of the present invention is achieved in this way, a kind of preparation method of aluminum-air battery air electrode catalyst, comprising the following steps:

(a), respectively weigh 0.85～0.87g of lanthanum nitrate hexahydrate, 0.63～0.64g of strontium nitrate, 1.00～1.02g of cobalt nitrate hexahydrate, 0.40～0.41g of ferric nitrate nonahydrate and 0.26～0.27g of niobium oxalate, add 200ml Deionized water forms a metal salt solution, denoted as solution A;

(b), weigh 1.55～1.58g of citric acid powder and add it into solution A, stir until dissolved, and record as solution B;

(c), take by weighing 0.29～0.30g ethylenediaminetetraacetic acid and add in solution B, then add ammoniacal liquor to adjust pH of solution to 4, stir 0.5-1 hour;

(d), continuously stirring the solution obtained in step (c) in a water bath at 80°C until a gel is formed, and then placing the gel in a 90°C oven to dry for 12 hours to form a gel-like precursor;

(e), the precursor is heated to 650°C for 1 hour at a rate of 3°C/min, and then continues to be heated to 700°C at a rate of 1°C/min, and then heated for 3 hours, and then naturally cooled to obtain aluminum- Air battery air electrode catalyst.

Preferably, in step (a), weigh 0.866 g of lanthanum nitrate hexahydrate, 0.635 g of strontium nitrate, 1.019 g of cobalt nitrate hexahydrate, 0.404 g of ferric nitrate nonahydrate, and 0.269 g of niobium oxalate;

In step (b), citric acid is 1.576g;

In step (c), ethylenediaminetetraacetic acid is 0.292g.

The preparation method of the air electrode of the aluminum-air battery is as follows: respectively weigh 0.240 g of the air electrode catalyst, 0.030 g of acetylene black, and 0.030 g of vinylidene fluoride, mix them evenly, and add 4 to 6 drops of N-methylpyrrolidone dropwise to make the mixture as In the form of slurry, it was coated on a nickel mesh with a thickness of 1.2 mm for the coating catalyst layer, and then placed in a blast drying oven and heated at 60° C. for 1 hour to obtain an air electrode for an aluminum-air battery.

Further limited, the conductive carbon is acetylene black, and the binder is polyvinylidene fluoride (PVDF).

Further limited, the coating process is completed by a fully automatic coating machine.

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

1. The raw materials used in the present invention are cheap and easy to obtain products, and the technological process is simple, which greatly reduces the production cost and production cycle of the catalyst and the air electrode of the aluminum-air battery.

2. The metal oxide catalyst prepared by the present invention has the advantages of fine particle size, uniform particle size, large specific surface area, high catalytic activity and stable chemical properties.

3. The aluminum-air battery air electrode prepared by the invention has the advantages of high discharge voltage, good stability, long service life and the like.

Description of drawings

FIG. 1 is the XRD pattern of the catalyst obtained in Example 1. FIG.

FIG. 2 is a SEM image of the catalyst obtained in Example 1. FIG.

FIG. 3 is a BET diagram of the catalyst obtained in Example 1. FIG.

FIG. 4 is a graph of the discharge voltage of the catalyst obtained in Example 1 under different current densities in an aluminum-air battery.

FIG. 5 is the degradation curve of the catalyst obtained in Example 1 in an aluminum-air battery at a current density of 40 mA cm ⁻² .

Detailed ways

Embodiment 1: the air electrode catalyst of a kind of aluminium-air battery in the present embodiment and preparation method thereof are carried out according to the following steps:

(a), weigh 0.866g of lanthanum nitrate hexahydrate, 0.635g of strontium nitrate, 1.019g of cobalt nitrate hexahydrate, 0.404g of ferric nitrate nonahydrate and 0.269g of niobium oxalate, add 200ml of deionized water to form a metal salt solution, denoted as solution A.

(b), weigh 1.576g of citric acid and add it to solution A, stir until dissolved, and record it as solution B.

(c), weigh 0.292g of ethylenediaminetetraacetic acid and add it to solution B, then add ammonia water to adjust the pH of the solution to 4, and stir for 0.5-1 hour.

(d), stirring the solution obtained in step (c) in a water bath at 80° C. until a gel is formed, and then placing the gel in an oven at 90° C. to dry for 12 hours to form a gel-like precursor.

(e), the precursor is heated to 650°C for 1 hour at a rate of 3°C/min, and then continues to be heated to 700°C at a rate of 1°C/min, and then heated for 3 hours, and then naturally cooled to obtain nano-calcium The titanium ore material La _0.4 S _r0.6 Co _0.7 Fe _0.2 Nb _0.1 O ₃ .

Figure 1 is the XRD pattern of the catalyst obtained in Example 1: it can be seen from Figure 1 that the XRD results confirm that the catalyst with good crystallinity was synthesized in this work.

Fig. 2 is an SEM image of the catalyst obtained in Example 1. It can be seen from Fig. 2 that the particle size of the catalyst is small and uniform, with an average particle size of about 100 nm, and exhibits a loose and porous structure.

Figure 3 shows the BET diagram of the catalyst obtained in Example 1, the material has a larger specific surface area. The larger the specific surface area, the stronger the adsorption capacity as the contact area between the catalyst and oxygen increases. This allows the catalyst to have more active sites and increases the rate and capability of oxygen catalysis.

The preparation method of the air electrode of the present embodiment is carried out according to the following steps:

Weigh out 0.240 g of air electrode catalyst, 0.030 g of acetylene black, and 0.030 g of vinylidene fluoride, respectively, and mix them evenly. The thickness was 1.2 mm, coated on a nickel mesh, and then placed in a blast drying oven, heated at 60° C. for 1 hour, to obtain an air electrode for an aluminum-air battery.

The air cathode and aluminum metal anode were assembled into a single cell, and the discharge performance of the aluminum-air battery was tested in the electrolyte 4M potassium hydroxide.

Figure 4 is a graph of the discharge voltage of the catalyst obtained in Example 1 under different current densities in an aluminum-air battery, and it can be seen from Figure 4 that the catalyst is at 10mA cm ^-2 , 20mA cm ^-2 , 40mA cm ^-2 , 60mA cm ^{-2 2.} The discharge voltages at the current density of 80mA cm ^-2 are 1.520V, 1.257V, 1.146V, 0.974V, and 0.832V, respectively. The catalyst enables the aluminum-air battery to have a higher discharge voltage.

Figure 5 shows the degradation curve of the catalyst obtained in Example 2 in the aluminum-air battery at a current density of 40 mA cm ^-2 . It can be seen from Figure 5 that the battery voltage is almost constant after 175 hours of stable testing, indicating that This catalyst enables aluminum-air batteries with excellent stability.

The basic principles and main features of the present invention and the advantages of the present invention are shown and described above. What is described in the above embodiments and descriptions is only to illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will also There are various changes and modifications which fall within the scope of the claimed invention. All equivalent changes or modifications made according to the spirit of the present invention should be included within the protection scope of the present invention.

Claims (9)

1. an aluminum-air battery air electrode catalyst, it is characterized in that, the molecular formula of this catalyst is La _0.4 S _r0.6 Co _0.7 Fe _0.2 Nb _0.1 O ₃ , which is aggregated by perovskite structure particles with an average particle size of 100 nm A loose porous morphology is formed. 2. a preparation method of aluminum-air battery air electrode catalyst as claimed in claim 1, is characterized in that, comprises the steps: (a), respectively weigh 0.85～0.87g of lanthanum nitrate hexahydrate, 0.63～0.64g of strontium nitrate, 1.00～1.02g of cobalt nitrate hexahydrate, 0.40～0.41g of ferric nitrate nonahydrate and 0.26～0.27g of niobium oxalate, add 200ml Deionized water forms a metal salt solution, denoted as solution A; (b), weigh 1.55～1.58g of citric acid powder and add it into solution A, stir until dissolved, and record as solution B; (c), take by weighing 0.29～0.30g ethylenediaminetetraacetic acid and add in solution B, then add ammoniacal liquor to adjust pH of solution to 4, stir 0.5-1 hour; (d), continuously stirring the solution obtained in step (c) in a water bath at 80°C until a gel is formed, and then placing the gel in a 90°C oven to dry for 12 hours to form a gel-like precursor; (e), the precursor is heated to 650°C for 1 hour at a rate of 3°C/min, and then continues to be heated to 700°C at a rate of 1°C/min, and then heated for 3 hours, and then naturally cooled to obtain aluminum- Air battery air electrode catalyst. 3. the preparation method of aluminum-air battery air electrode catalyst according to claim 1, is characterized in that, in step (a), taking by weighing lanthanum nitrate hexahydrate is 0.866g, strontium nitrate is 0.635g, and cobalt nitrate hexahydrate is 1.019 g, 0.404 g of ferric nitrate nonahydrate, and 0.269 g of niobium oxalate. 4. The preparation method of aluminum-air battery air electrode catalyst according to claim 1, wherein in step (b), citric acid is 1.576g. 5. The preparation method of aluminum-air battery air electrode catalyst according to claim 1, is characterized in that, in step (c), ethylenediaminetetraacetic acid is 0.292g. 6. Use of the aluminum-air battery air electrode catalyst as claimed in claim 1 for preparing an air electrode in an aluminum-air battery. 7. The purposes of the aluminum-air battery air electrode catalyst according to claim 6, characterized in that, respectively weigh 0.240g of air electrode catalyst, 0.030g of acetylene black, and 0.030g of vinylidene fluoride, mix well, and dropwise add N - 4-6 drops of methylpyrrolidone were mixed into a slurry, coated on a nickel mesh with a thickness of 1.2 mm for the catalytic layer, then placed in a blast drying oven, heated at 60°C for 1 hour to obtain aluminum-air The air electrode of the battery. 8. The use of the aluminum-air battery air electrode catalyst according to claim 7, wherein the conductive carbon is acetylene black, and the binder is polyvinylidene fluoride. 9 . The use of the aluminum-air battery air electrode catalyst according to claim 7 , wherein the coating process is completed by a fully automatic coating machine. 10 .

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