Preparation method of aluminum anode material of aluminum-air battery

Abstract

The invention discloses an aluminum anode material for an aluminum air battery and a preparation method of the aluminum anode material. The aluminum anode material mainly comprises the following components in percentage by mass: 0.06-0.1% of gallium, 0.13-0.28% of lead, 0.20-0.40% of tin, 0.04-0.15% of bismuth, less than or equal to 0.01% of impurities and the balance of aluminum, and the purities of the raw materials are greater than or equal to 99.99%. The preparation method comprises the following steps: preparing materials; smelting: firstly adding high-purity aluminum, adding proportioned Bi, Ga, Sn and Pb metal raw materials to the bottom of molten aluminum after the high-purity aluminum is completely molten, adding a refining agent after the alloy is completely molten, standing, removing slag, keeping the temperature for 1 hour by using covering cotton, pouring into a mold, and naturally cooling; milling is conducted; cold-rolling an aluminum plate; and carrying out annealing treatment to obtain the aluminum anode material of the aluminum-air battery. A cold rolling and homogenizing annealing process is adopted, grains are refined, segregation is eliminated, lamellar uniform dissolution of an aluminum matrix is promoted, local corrosion is inhibited, the process is simplified, operation is easy, and large-batch machining of the aluminum anode material can be achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of aluminum-air batteries, and particularly relates to a preparation method of an aluminum anode material for an aluminum-air battery. BACKGROUND

[0002] The aluminum-air battery is a new type of environment-friendly energy battery, and its working principle is to generate electric energy through the reaction of aluminum and air. No chemical substances need to be added during operation, and no harmful gases or solid wastes are discharged, so the aluminum-air battery is considered as a green technology with great potential.

[0003] It is proved through systematic experimental research that the new type of aluminum-based anode material prepared by using the micro-alloying technology can significantly inhibit the self-corrosion of the aluminum matrix, thereby improving the electrochemical performance index. The existing technical documents record that introducing alloying elements such as Ga, Sn, Mg and Zn into pure aluminum can effectively promote the decomposition of the oxide film or control the hydrogen evolution overpotential, thereby improving the anode activation characteristics. CN105140596A discloses an aluminum alloy anode material for an air battery, a preparation method and an aluminum-air battery. The aluminum alloy anode material is composed of the following components in percentage by weight: Zn: 0.05%-6%, Ga: 0.05%-4%, In: 0.01%-2%, and the balance is Al. The aluminum alloy anode material significantly improves the electrochemical performance of the anode and reduces the self-corrosion rate by alloying, and the self-corrosion rate is less than 5.12 mg / cm 2CN117187634A discloses an aluminum anode material for titanium-containing aluminum air fuel cell and a preparation method thereof, which mainly consists of the following components in mass percentage: magnesium: 0.4-1%, indium: 0.1-0.4%, titanium: 0.01-0.1%, impurity content not more than 0.01%, and the balance of aluminum. By means of high-purity aluminum micro-alloying, alloying elements Mg, In, Ti, etc. are added to improve the electrochemical performance of the aluminum anode and reduce the hydrogen evolution behavior of the aluminum anode, so as to achieve the "activation" of the aluminum alloy anode. These elements often have a high hydrogen evolution overpotential and are used to damage the oxide film to some extent, and can also refine the grains or remove impurities. CN110042278A discloses an aluminum air battery anode material and a preparation method thereof, which mainly consists of the following components in mass percentage: antimony: 0.2-0.4%, manganese: 0.3-0.6%, zirconium: 0.1-0.3%, lead: 0.01-0.05%, tin: 0.01-0.05%, and the balance of aluminum. The preparation method comprises the following steps: batching, melting: adding the proportioned aluminum ingot, aluminum manganese intermediate alloy and aluminum zirconium intermediate alloy into the melting furnace in multiple times for melting; after complete melting, adding metal antimony, metal lead and metal tin; adding a mixture of hexachloroethane and titanium dioxide, removing waste slag, pouring into a mold, natural cooling, rolling aluminum sheet, heat treatment, and obtaining the aluminum air battery aluminum anode material. The self-corrosion hydrogen evolution rate is greatly reduced, and the utilization rate of the aluminum anode reaches more than 90%.

[0004] However, the current technical solutions have the following constraints: the combination of high-purity aluminum material (99.99%) and noble metal additives significantly increases the material cost. In view of the above technical bottleneck, it is particularly important to find an aluminum alloy anode material with a suitable proportion of alloying elements; at the same time, it is also particularly important to find a suitable and simple production process to reduce the segregation of alloying elements. SUMMARY

[0005] One of the purposes of the present application is to provide an aluminum air battery aluminum anode material.

[0006] The second purpose of the present application is to provide a preparation method of the above-mentioned aluminum air battery aluminum anode material.

[0007] To achieve the above-mentioned purposes, the present application adopts the following technical solutions:

[0008] On the one hand, the present application provides an aluminum air battery aluminum anode material, which is composed of the following components in mass percentage: gallium (Ga) 0.06-0.1%, lead (Pb) 0.13-0.28%, tin (Sn) 0.20-0.40%, bismuth (Bi) 0.04-0.15%, impurity content not more than 0.01%, and the balance of aluminum (Al).

[0009] In another aspect, the application provides a preparation method of the aluminum anode material for the aluminum-air battery, comprising the following steps:

[0010] S1, weighing Ga, Pb, Sn, Bi and Al raw materials according to the material component ratio;

[0011] S2, first adding the weighed high-purity aluminum into the pretreated smelting furnace, heating to melt, synchronously adding a covering agent to isolate air, after the aluminum is completely melted, adding the Ga, Pb, Sn and Bi raw materials wrapped by aluminum foil into the aluminum liquid, slowly stirring until uniform, after the alloy is completely melted, adding a refining agent when the alloy melt temperature reaches 720℃, after the reaction, standing, deslagging, heat preservation for 1 hour, pouring the molten liquid into a mold, natural cooling for 30-50 min, and obtaining an aluminum ingot;

[0012] S3, fixing the cooled aluminum ingot on a milling table, cutting the rough part, and obtaining a cast aluminum ingot with smooth surface;

[0013] S4, performing rolling treatment on the cast aluminum ingot, and obtaining an aluminum alloy plate;

[0014] S5, performing homogenization annealing treatment on the rolled aluminum alloy plate, and obtaining the aluminum-air battery anode material.

[0015] Preferably, in step S2, the covering agent is composed of the following raw materials in mass percentage: NaF 14%, NaCl 38%, KCl 48%, and is uniformly mixed before use, and is preheated and dried, and the amount is used according to the principle of uniform distribution on the surface of the aluminum melt.

[0016] Preferably, the Bi, Ga, Sn and Pb metal raw materials are preheated at 220℃ for 60 min, are placed in a bell jar, and are pressed into the bottom of the aluminum liquid, and after the alloy is completely melted, the bell jar is taken out.

[0017] Preferably, the stirring mode in step S2 is electromagnetic auxiliary stirring, the frequency is 15-30 Hz, each stirring is 15 min, the interval is 30 min, the composition is ensured to be uniform, the stirring direction is changed after each stirring, the interval of forward and reverse stirring is set to 15 seconds, and before standing, low-speed stirring is performed for 5-10 min to stabilize the melt and reduce gas inclusions.

[0018] Preferably, in step S2, the refining agent is Na3AlF6, and the addition amount is 2% of the mass of the high-purity aluminum used each time.

[0019] Preferably, the milling parameters in step S3 are a cutting speed of 150-300 m / min and a feed speed of 100-350 mm / min.

[0020] Preferably, in step S4, the rolling mode is cold rolling, and the compression amount is 40% each time.

[0021] Preferably, in step S5, the annealing temperature is 450℃, the annealing time is 8-48h, and the cooling mode is air cooling.

[0022] Compared with the prior art, the present application has the following beneficial effects:

[0023] 1. The aluminum anode material of the present application is prepared by adding Ga (0.06-0.1%), Pb (0.13-0.28%), Sn (0.20-0.40%) and Bi (0.04-0.15%) and combining cold rolling with 450℃ annealing (8-48h). Ga can make the potential negative shift to -1.45V to -1.59V by destroying the continuity of the aluminum surface oxide film, thus improving the activation performance; Sn and Pb have the common effect of destroying and decomposing the passivation film of the aluminum anode, reducing the anode polarization, and synergistically inducing micropores and inhibiting hydrogen evolution, and the current efficiency is more than 85%; Bi forms nanoparticles at the grain boundary to hinder the corrosion path.

[0024] 2. The production process of the present application is simple and easy to mass-produce. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 Nyquist diagram of Example 1-3 of the present application.

[0026] Figure 2 Open-circuit voltage diagram of Example 1-3 of the present application.

[0027] Figure 3 Metallographic structure of the aluminum anode material alloy prepared in Example 1 of the present application.

[0028] Figure 4 Metallographic structure of the aluminum anode material alloy prepared in Example 2 of the present application.

[0029] Figure 5 Metallographic structure of the aluminum anode material alloy prepared in Example 3 of the present application.

[0030] Figure 6 Equivalent circuit diagram of the aluminum anode material of the present application. DETAILED DESCRIPTION

[0031] The embodiments of the present application will be described in detail below. The embodiments described below are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0032] The covering agent used in the following examples is composed of the following raw materials in mass percentage: NaF 14%, NaCl 38%, KCl 48%, which are mixed uniformly before use, preheated and dried, and used in principle in an amount of uniform spreading on the surface of the aluminum melt.

[0033] In the following examples, the smelting furnace needs to be pretreated by heating to 300℃ and keeping for 120min.

[0034] Example 1

[0035] An aluminum-air battery anode material, which is composed of and has the following mass percentage contents: gallium (Ga) 0.06%, lead (Pb) 0.13%, tin (Sn) 0.20%, bismuth (Bi) 0.04%, impurities not more than 0.01%, and the balance being aluminum (Al).

[0036] The preparation method of the aluminum-air battery anode material in this example comprises the following steps:

[0037] S1, batching: Ga, Pb, Sn, Bi and Al raw materials with a purity of ≥99.99% are weighed according to the component ratio; the weighed Ga, Pb, Sn and Bi are wrapped with aluminum foil with a purity of 99.99% and then kept at 220℃ for 60min;

[0038] S2, smelting: the weighed high-purity aluminum is first added to the pretreated smelting furnace and heated to melting at a frequency of 152Hz, and the covering agent is added synchronously to isolate air; when the aluminum liquid reaches 660℃ after the aluminum is completely melted, the pre-kept Ga, Pb, Sn and Bi are placed in the bell jar and pressed into the bottom of the aluminum liquid, and then slowly stirred until uniform, with electromagnetic auxiliary stirring at a frequency of 15-30Hz, 15min each time, 30min interval, to ensure uniformity, and the stirring direction is changed after each stirring, with a 15-second interval for forward and reverse stirring, and low-speed stirring for 5-10min before standing to stabilize the melt and reduce gas inclusions; after the alloy is completely melted, the bell jar is removed, and when the alloy melt temperature reaches 720℃, 2% of high-purity aluminum is added as a refining agent, and after reaction, the slag is removed and kept warm with insulation cotton for 1 hour; fireproof cotton is laid at the pouring port, the smelting furnace is slowly lifted away from the mold side, the molten aluminum slowly flows into the mold through the fireproof cotton, and the aluminum ingot is obtained after natural cooling for 40min;

[0039] S3, the cooled aluminum ingot is fixed on a milling table, the cutting speed is set to 150m / min, the feed speed is set to 100-350mm / min, and the rough part is cut to obtain a cast aluminum ingot with smooth surface;

[0040] S4, the cast aluminum alloy (thickness 47mm) is cold-rolled into an aluminum alloy plate with a thickness of 6mm;

[0041] S5, homogenizing annealing the obtained rolled aluminum alloy sheet at 450℃ for 8h, air cooling, allowing the alloying elements to diffuse uniformly at high temperature, obtaining an annealed piece, i.e. the aluminum alloy anode material.

[0042] Example 2

[0043] An aluminum-air battery anode material, the composition and mass percentage content of which are: gallium (Ga) 0.1%, lead (Pb) 0.13%, tin (Sn) 0.40%, bismuth (Bi) 0.04%, impurity content not more than 0.01%, and the balance being aluminum (Al).

[0044] The preparation method of the aluminum-air battery anode material of the present embodiment comprises the following steps:

[0045] S1, batching: weighing Ga, Pb, Sn, Bi and Al raw materials with a purity of ≥99.99% according to the material component ratio; wrapping the weighed Ga, Pb, Sn and Bi with aluminum foil with a purity of 99.99% and then heat treating at 220℃ for 60min;

[0046] S2, smelting: first, add the weighed high-purity aluminum into the pretreated smelting furnace and heat to melting at a frequency of 152Hz, synchronously add covering agent to isolate air, when the aluminum is completely melted and the temperature of the aluminum liquid reaches 660℃, place the pre-heated Ga, Pb, Sn and Bi in the bell jar and press into the bottom of the aluminum liquid, slowly stir until uniform, the stirring mode is electromagnetic auxiliary stirring, the frequency is 15-30Hz, each stirring lasts for 15min, the interval is 30min, ensure the uniformity of the components, change the stirring direction after each stirring, the interval for reversing during forward and reverse stirring is 15 seconds, before standing, low-speed stirring lasts for 5-10min, stabilize the melt to reduce gas inclusions. After the alloy is completely melted, remove the bell jar, when the temperature of the alloy melt reaches 720℃, add 2% of high-purity aluminum as refining agent, after the reaction, stand, remove the slag, cover with heat preservation cotton for 1 hour, lay fireproof cotton at the pouring opening, slowly lift the smelting furnace away from the mold side, make it slowly flow into the mold through the fireproof cotton, and naturally cool for 40min to obtain aluminum ingots;

[0047] S3, fix the cooled aluminum ingots on the milling table, set the cutting speed to 200m / min and the feed speed to 100-350mm / min, cut the rough part to obtain a cast aluminum ingot with smooth surface;

[0048] S4, cold roll the cast aluminum alloy (thickness 47mm) into an aluminum alloy sheet with a thickness of 6mm;

[0049] S5, homogenizing anneal the obtained rolled aluminum alloy sheet at 450℃ for 24h, air cooling, allowing the alloying elements to diffuse uniformly at high temperature, obtaining an annealed piece, i.e. the aluminum alloy anode material.

[0050] Example 3

[0051] An aluminum-air battery anode material, the composition and mass percentage content are: gallium (Ga) 0.06%, lead (Pb) 0.28%, tin (Sn) 0.20%, bismuth (Bi) 0.15%, impurity content not more than 0.01%, the balance is aluminum (Al).

[0052] The preparation method of the aluminum-air battery anode material in this embodiment comprises the following steps:

[0053] S1, batching: according to the material component ratio, the purity of Ga, Pb, Sn, Bi and Al raw materials is ≥99.99%; the weighed Ga, Pb, Sn and Bi are wrapped with aluminum foil with a purity of 99.99% and then heat treated at 220℃ for 60min;

[0054] S2, smelting: first, put the weighed high-purity aluminum into the pretreated smelting furnace, heat to melting at a frequency of 152Hz, and synchronously add covering agent to isolate air; when the aluminum is completely melted and the temperature of the aluminum liquid reaches 660℃, put the pre-heated Ga, Pb, Sn and Bi into the bell jar and press into the bottom of the aluminum liquid, slowly stir until uniform, the stirring mode is electromagnetic auxiliary stirring, the frequency is 15-30Hz, each stirring time is 15min, the interval is 30min, and the stirring direction is changed after each stirring, the interval is set to 15 seconds during forward and reverse stirring, and low-speed stirring is performed for 5-10min before standing to stabilize the melt and reduce gas inclusions; after the alloy is completely melted, remove the bell jar, when the alloy melt temperature reaches 720℃, add 2% of high-purity aluminum as refining agent, and after reaction, stand, remove slag, cover with heat preservation cotton for 1 hour, lay fireproof cotton at the pouring opening, slowly lift the smelting furnace away from the mold side, make it flow slowly into the mold through the fireproof cotton, and naturally cool for 40min to obtain aluminum ingot;

[0055] S3, fix the cooled aluminum ingot on the milling table, set the cutting speed to 300m / min and the feed speed to 100-350mm / min, cut the rough part to obtain a cast aluminum ingot with smooth surface;

[0056] S4, cold roll the cast aluminum alloy (thickness 47mm) into an aluminum alloy plate with a thickness of 6mm;

[0057] S5, homogenize the obtained rolled aluminum alloy plate at 450℃ for 48h, and air cool to make the alloy elements diffuse uniformly at high temperature to obtain an annealed piece, that is, the aluminum alloy anode material.

[0058] Table 1 EIS fitting parameters of different examples

[0059]

[0060] Combining electrochemical EIS data and equivalent circuit diagrams ( Figure 6 The EIS fitting parameters were obtained using the ZsimpWin software, as shown in Table 1. The equivalent circuit diagram consists of a resistor R and a constant phase element (CPE). The CPE is a circuit element used in electrochemical impedance spectroscopy (EIS) to describe the behavior of non-ideal capacitance. Its core characteristic is that its phase angle remains constant over a wide frequency range, not changing with frequency. Its constant phase characteristic quantifies interfacial inhomogeneity and dynamic behavior. Rct and CPE2 represent the resistance and capacitance of the double layer (electrode surface and solution), respectively. Factors such as surface roughness and heterogeneity affect the behavior of non-ideal capacitance, while the constant phase element CPE can compensate for inhomogeneity. Ω CPE1 and Rs represent the resistance and capacitance of the corrosion products on the material surface, respectively, and Rs represents the solution resistance. Based on the EIS fitting parameters in Table 1 and... Figure 1 The Nyquist curves show that Example 3 (blue curve) has the smallest high-frequency semicircle diameter, indicating its charge transfer resistance (R0). ct The lowest value and best reactivity were observed, consistent with the EIS fitting parameters in Table 1; Example 1 (black curve) showed the largest semicircle and Rct as high as 34 Ω·cm. 2 The reaction resistance was the highest, the activity was weakest, and no obvious diffusion impedance line appeared in the low-frequency region, suggesting that the surface reaction of the material is dominated by charge transfer, with diffusion having a relatively small impact. The solution resistance Rs in Example 3 was 7.271 Ω·cm. 2 The value was the lowest among the three, lower than that of Example 1 (Rs = 9.221 Ω·cm). 2 Example 1) and Example 2 (Rs = 8.792 Ω·cm) 2 This indicates that Example 3 exhibits the best electrolyte ion transport efficiency and the lowest interfacial contact impedance. This is consistent with the measured open-circuit voltage results, such as... Figure 2 As shown, after a test time of 1800s, the open-circuit potentials all tended to stabilize, with voltages approximately between -1.45V and -1.59V. The more negative the electrode potential, the easier it is to lose electrons, resulting in a stronger discharge capability; therefore, Example 3 exhibited the best discharge capability. In the double-layer characteristics, the CPE1 value (2.198 × 10⁻⁶) is... -5 F·cm 2 Although lower than other embodiments, the n1 index (0.855) reflects that the microporous structure balances charge storage capacity with active site exposure; the CPE2 parameter (1.601 × 10⁻⁶) -2 F·cm 2) and n2 index (0.395) are more inclined to the resistance characteristics, indicating that the oxide film is highly porous, the mass transfer process is dominated by ohm, the resistance mainly comes from the electrolyte or the resistance of the material itself, and the ion migration rate is faster.

[0061] Figures 3-5 The metallographic structure diagrams of examples 1-3 are respectively, by comparing with each other, it is concluded that the uniformity of the structure distribution and the fineness of the second phase particles become better with the prolongation of the holding time, and when the holding time is up to 48h, the second phase particles are much finer than the samples with holding time of 8h and 24h. Combined with the impedance spectrum and the EIS fitting parameter results, the grain of the aluminum anode material after homogenization annealing treatment is refined, the grain boundary is increased, the corrosion is more uniform, and the charge transfer efficiency is greatly improved; the element distribution is uniform, the segregation of Sn, Bi and other elements is eliminated, the aggregation of alloy elements (such as Ga, Sn) at the grain boundary is avoided, and the occurrence of local corrosion is inhibited. The charge transfer resistance Rct (9.704Ω·cm 2 ) of example 3 is lower than that of example 1 (34.00Ω·cm 2 ) and example 2 (15.33Ω·cm 2 ), which indicates that the long annealing time makes the passivation film generated on the surface of the sample dense and stable, inhibits the corrosion behavior related to charge transfer, and improves the corrosion resistance of the sample.

[0062] The specific embodiments of the present application are described in detail above. However, it should be emphasized that the present application is not limited to the above specific embodiments. Those skilled in the art can make various modifications, improvements or adjustments according to actual needs or technical progress without departing from the scope of the claims of the present application.

Claims

1. An aluminum anode material for an aluminum-air battery, characterized in that, The aluminum anode material is composed of the following components by mass percentage: gallium 0.06-0.1%, lead 0.13-0.28%, tin 0.20-0.40%, bismuth 0.04-0.15%, impurity content not exceeding 0.01%, and the balance being aluminum.

2. A method for preparing the aluminum anode material for an aluminum-air battery according to claim 1, characterized in that, Includes the following steps: S1, weigh out gallium, lead, tin, bismuth and aluminum raw materials according to the material composition ratio; S2. First, weighed high-purity aluminum is added to the pre-treated melting furnace and heated until it melts. At the same time, a covering agent is added to isolate the air. After the aluminum is completely melted, gallium, lead, tin and bismuth raw materials wrapped in aluminum foil are added to the aluminum liquid and stirred slowly until uniform. After the alloy is completely melted, when the temperature of the alloy melt reaches 720°C, a refining agent is added. After the reaction, the mixture is allowed to stand, slag is removed, and the temperature is maintained for 1 hour. The molten liquid is poured into a mold and cooled naturally for 30-50 minutes to obtain aluminum ingots. S3, fix the cooled aluminum ingot on the milling table, cut the rough parts, and obtain a cast aluminum ingot with a smooth and flat surface; S4, the cast aluminum ingot is rolled to obtain aluminum alloy sheet; S5, homogenization annealing treatment is performed on rolled aluminum alloy sheet to obtain aluminum-air battery anode material.

3. The method for preparing an aluminum anode material for an aluminum-air battery according to claim 2, characterized in that, In step S2, the pretreatment method of the smelting furnace is as follows: heating to 300℃ and holding for 120 minutes; wrapping the metal raw materials Bi, Ga, Sn and Pb with aluminum foil and holding at 220℃ for 60 minutes.

4. The method for preparing an aluminum anode material for an aluminum-air battery according to claim 2, characterized in that, In step S2, the stirring method is electromagnetic assisted stirring, the frequency is 15-30Hz, each stirring lasts 15 minutes, with a 30-minute interval to ensure uniform composition. After each stirring, the stirring direction is changed, and the interval between forward and reverse stirring is set to 15-20 seconds. Before settling, the mixture is stirred at low speed for 5-10 minutes to stabilize the melt and reduce gas inclusions.

5. The method for preparing an aluminum anode material for an aluminum-air battery according to claim 2, characterized in that, In step S2, the covering agent is composed of the following raw materials in the following mass percentages: NaF 14%, NaCl 38%, KCl 48%. It is mixed evenly before use, and then preheated and dried. The dosage principle is to spread it evenly on the surface of the aluminum melt.

6. The method for preparing an aluminum anode material for an aluminum-air battery according to claim 2, characterized in that, In step S2, the refining agent is Na3AlF6, and the amount added is 2% of the mass of high-purity aluminum used each time.

7. The method for preparing an aluminum anode material for an aluminum-air battery according to claim 2, characterized in that, In step S3, the milling parameters are a cutting speed of 150-300 m / min and a feed rate of 100-350 mm / min.

8. The method for preparing an aluminum anode material for an aluminum-air battery according to claim 2, characterized in that, In step S4, the rolling method is cold rolling, and the compression amount is 40% each time.

9. The method for preparing an aluminum anode material for an aluminum-air battery according to claim 2, characterized in that, In step S5, the annealing temperature is 450°C, the time is 8 to 48 hours, and the cooling method is air cooling.

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