TWI812577B - Manufacturing method of aluminum alloy anode of chemical battery and aluminum alloy anode - Google Patents

Abstract

The invention provides a method for manufacturing an aluminum alloy anode of a chemical battery, which includes a preparation step, a heat treatment step, and a molding step. The preparation step is to provide an aluminum alloy composite material. Based on the weight percentage of the aluminum alloy composite material being 100wt%, the aluminum alloy composite material contains: 3~10wt% zinc, 0.05~5wt% tin, 0.05~5wt% Indium, 0.05~5wt% bismuth, and the balance aluminum. The heat treatment step is to melt and mix the aluminum alloy composite material, flush it with inert gas for at least 10 minutes and maintain the temperature for a predetermined time. The molding step is to The aluminum alloy composite material is cooled to 700~800°C, and the aluminum alloy anode is produced by mold casting. In addition, the present invention also provides an aluminum alloy anode, which has a precipitate precipitated along the grain boundaries of the crystal grains, and the precipitate is an intermetal containing aluminum (Al)-indium (In)-bismuth (Bi). compound.

Description

Method for manufacturing aluminum alloy anode of chemical battery and aluminum alloy anode

The present invention relates to a manufacturing method of an aluminum alloy anode and an aluminum alloy anode, in particular to a manufacturing method of an aluminum alloy anode used as a sacrificial anode for metal protection in chemical batteries, and an aluminum alloy anode prepared by the manufacturing method.

Since aluminum alloy has the advantages of low electrode potential, high electrochemical equivalent, excellent electrochemical characteristics, good corrosion resistance, wide application range, and cheapness, batteries using aluminum alloy as anode material and cathode protection are One of the most widely studied battery types.

However, since aluminum is a highly active amphoteric metal, it is prone to self-corrosion in acidic or alkaline solutions. In addition, an oxide layer will be formed on the surface of the aluminum alloy anode during the reaction process. This oxide layer will also reduce the activity of the aluminum alloy anode, leading to poor current efficiency and other problems. Therefore, currently common aluminum alloy anode materials are generally used to add trace active elements of different types and content proportions to aluminum to reduce self-corrosion phenomena, inhibit side reactions, and improve current efficiency.

Therefore, it is an object of the present invention to provide an aluminum alloy anode for chemical batteries that can maintain anode activity and cathode protection.

Therefore, the manufacturing method of the aluminum alloy anode of the present invention includes a preparation step, a heat treatment step, and a molding step. The preparation step is to provide an aluminum alloy composite material. Based on the weight percentage of the aluminum alloy composite material being 100wt%, the aluminum alloy composite material contains: 3~10wt% zinc (Zn), 0.05~5wt% tin (Sn) ), 0.05~5wt% indium (In), 0.05~5wt% bismuth (Bi), and the balance aluminum (Al). The heat treatment step involves melting and mixing the aluminum alloy composite material at a temperature of 1000 to 1200°C, flushing the melted aluminum alloy composite material with inert gas for at least 10 minutes, and maintaining the temperature for a predetermined time. The molding step is to cool the temperature of the aluminum alloy composite material that has undergone the heat treatment step to 700~800°C, and use the molding method to prepare the aluminum alloy anode.

In addition, another object of the present invention is to provide an aluminum alloy anode.

Therefore, the aluminum alloy anode of the present invention is manufactured by the aluminum alloy anode manufacturing method as described above. Wherein, the aluminum alloy anode has precipitates precipitated along grain boundaries, and the precipitates contain an intermetallic compound composed of aluminum (Al)-indium (In)-bismuth (Bi).

The effect of the present invention is to use an aluminum alloy composite material containing active elements of zinc, tin, indium and bismuth as the aluminum alloy anode of the battery. Since the zinc, tin, indium and bismuth of the aluminum alloy composite material are involved in the electrochemical reaction process The co-precipitated precipitates can have higher solubility characteristics and can destroy the oxide layer on the surface of the aluminum alloy anode, thereby maintaining the activity of the aluminum alloy anode and improving the discharge efficiency of the battery.

Other features and effects of the present invention will be clearly presented in the embodiments with reference to the drawings, in which: Figure 1 is a metallographic diagram illustrating the microscopic images of comparative examples, comparative examples 1, 2 and specific examples of the present invention. ; Figure 2 is a Tafel curve chart, illustrating the current density-potential results measured by the LSV method for Comparative Examples, Comparative Examples 1, 2 and Specific Examples; Figure 3 is a scanning electron microscope image (hereinafter referred to as SEM) , illustrating the surface image results of the control example, comparative examples 1, 2, and specific examples measured by the LSV method; Figure 4 is a Nyquist chart illustrating the surface image results of the control example, comparative examples 1, 2, and specific examples. Electrochemical impedance (EIS) measurement results; and Figure 5 is a constant current potential spectrum, illustrating the potential-time measurement results of the control example, comparative examples 1, 2 and specific examples under constant current conditions.

Before the present invention is described in detail, it should be noted that similar elements are represented by the same numbers in the following description.

An embodiment of the aluminum alloy anode of the present invention is used as an anode for a chemical battery, and the aluminum alloy anode is composed of aluminum alloy composite materials.

The aluminum alloy composite material also contains zinc (Zn), tin (Sn), indium (In), bismuth (Bi) and other active elements, and based on the weight percentage of the aluminum alloy composite material being 100wt%, the aluminum alloy composite material Contains: 3~10wt% zinc (Zn), 0.05~5wt% tin (Sn), 0.05~5wt% indium (In), 0.05~5wt% bismuth (Bi), and the balance aluminum (Al) . The aluminum alloy anode has precipitates that precipitate along the grain boundaries of the crystal grains and form chain and granular forms, and the precipitates are intermetallic compounds containing aluminum (Al)-indium (In)-bismuth (Bi).

In some experimental examples, the zinc content of the aluminum alloy composite material ranges from 5 to 10 wt%.

In some experimental examples, the tin content of the aluminum alloy composite material ranges from 0.1 to 3.0wt%.

In some experimental examples, the indium content of the aluminum alloy composite material ranges from 0.1 to 3.0wt%.

In some experimental examples, the bismuth content of the aluminum alloy composite material ranges from 0.1 to 3.0 wt%.

In some experimental examples, the bismuth content of the aluminum alloy composite material ranges from 0.1 to 1.5 wt%, and the indium content ranges from 0.1 to 3.0 wt%.

The method of preparing an aluminum alloy anode using the aforementioned experimental example of the aluminum alloy composite material is described below.

Preparation step A, prepare an aluminum alloy with a composition as described in this experimental example composite materials.

In heat treatment step B, the aluminum alloy composite material is melted and mixed at a temperature of 1000 to 1200°C, and the melted aluminum alloy composite material is flushed with inert gas for at least 10 minutes and kept warm for a predetermined time.

Specifically, the heat treatment step B is to place the aluminum alloy composite material into a graphite crucible, then melt, mix and maintain the temperature at 1000°C for about 100 minutes. Then, under the same temperature conditions, the molten aluminum alloy composite material was flushed with nitrogen for about 20 minutes.

Next, a molding step C is performed, the temperature of the aluminum alloy composite material that has undergone the heat treatment step B is cooled to 700~800°C, and an aluminum alloy anode is produced by molding.

Specifically, the molding step C is to cool the aluminum alloy composite material that has undergone the heat treatment step B from 1000°C to 740°C at a cooling rate of 25°C/min. An aluminum alloy anode with a size of ^{120x100x25mm3} is then produced by die casting.

Next, anodes (aluminum alloy anodes, aluminum anodes) made of different composition materials and related electrochemical properties are described with the following specific examples, comparative examples and comparative examples.

Specific examples and comparative examples 1 and 2

The aluminum alloy anodes of this specific example and Comparative Examples 1 and 2 are both produced by the aforementioned manufacturing method. The difference lies in the active elements added to the aluminum alloy composite materials of this specific example and Comparative Examples 1 and 2. Types of active elements in this specific example and comparative examples 1 and 2 and contents are summarized in Table 1.

Comparative example: an aluminum anode prepared from pure aluminum (Al) 2N using the same manufacturing method as this specific example.

Referring to Figure 1, Figures 1(a)~(d) show the surfaces of aluminum anodes and aluminum alloy anodes prepared by Comparative Example, Comparative Examples 1, 2 and Specific Examples, respectively, through 1200-grit silicon carbide (SiC). Metallographic image after sandpaper grinding. It can be seen from Figure 1(a) that relatively dispersed precipitates with a particle size of about 5 μm will precipitate on the surface of the aluminum anode obtained after heat treatment and mold casting. After adding active elements to the aluminum alloy anode, it can be seen that the precipitates will gradually tend to precipitate near the grain boundary. And it can be seen from Figure 1(b)~(d) that when the added active elements are zinc and tin (Figure 1(b), Comparative Example 1), although there will be precipitates precipitating at the grain boundaries, this precipitation The particle size is large (about 50 μm) and dispersed; when the aluminum alloy anode contains zinc, tin, indium, and bismuth at the same time (Figure 1(d), specific example), it can be seen that the grains are smaller, and The precipitates that precipitate along the grain boundaries will tend to form chain-like precipitates distributed over the entire surface, and at the same time, precipitate particles with small particle sizes (about 5~10 μm) will precipitate. From the EDS analysis results of the aforementioned precipitates, it can be seen that the precipitates of the aluminum anode are iron-rich Al ₅ FeSi (Figure 1(a)), while the precipitates of the aluminum alloy anode after adding active elements are respectively They are inter-metallic compounds such as AlSn (Comparative Example 1), Al-Zn-Sn-In (Comparative Example 2), and Al-In-Bi (Specific Example).

In addition, refer to Figure 2. Figure 2 shows the aluminum alloy anode prepared in Comparative Example, Comparative Examples 1, 2 and Specific Examples, using a three-electrode system (reference electrode: Ag/AgCl, auxiliary electrode: copper foil, working electrode: control Example/Specific Example/Comparative Example), Tafel plots obtained after measurement using linear sweep voltammetry (LSV) in 37wt% KOH solution. It can be seen from the corrosion potential results in Figure 2 that the aluminum alloy anode (specific example) containing zinc, tin, indium, and bismuth produced in this case has the lowest corrosion potential ( E _corr : -1.66V), while the aluminum anode (control Example) has the highest corrosion potential ( E _corr : -1.54V), showing that the aluminum alloy anode containing zinc, tin, indium, and bismuth has the greatest electrochemical activity. It is inferred from this result that the anode made of aluminum alloy composite materials containing zinc, tin, indium, and bismuth has the smallest grains, so it can have the greatest polarization effect, and the bismuth penetrating the aluminum alloy anode material can also hinder Because the self-corrosion caused by the dissolution of bismuth can slow down the self-corrosion effect, it has better electrode polarization effect.

In addition, refer again to Figure 3. Figures 3(a)~(d) respectively show the aluminum anode (Comparative Example (a)) and the aluminum alloy anode (Comparative Example 1 (Comparative Example 1) after the linear sweep voltammetry (LSV) measurement. b), scanning electron microscope (SEM) images of Comparative Example 2(c) and Specific Example (d)), and from left to right are images of different magnifications at the framed areas in the figure. Among them, the bright part of the SEM image is the oxide layer formed on the surface of the grain. It can be seen from these SEM images that the oxide layer of the aluminum anode (shown in Figure 3(a)) will cover the surface of the anode, and The anode surface is prone to localized corrosion; and when it contains active elements, it is obvious from the results in Figure 3(b)~(d) that the aluminum alloy anode surface will be distributed to form a large number of precipitates after they are dissolved. The pores and cracks and the dissolved active elements will further destroy the oxide layer and cause pores and cracks in the oxide layer, and when the aluminum alloy anode contains zinc, tin, indium, and bismuth at the same time (Figure 3(d), specific example) , the surface of the aluminum alloy anode and oxide layer will form the most holes and cracks.

Further reference is made to Figures 4 and 5. Figure 4 shows electrochemistry of the aluminum anode (Comparative Example) and the aluminum alloy anode (Comparative Examples 1, 2 and Specific Examples) in a 37wt% KOH solution using the same three-electrode system as described above. The Nyquist spectrum obtained by impedance (EIS) measurement, Figure 5 is the potential measurement result of constant-current charging using constant-current. Among them, (a) to (d) in Figure 4 are 2N pure aluminum (comparative example), aluminum zinc (comparative example 1), aluminum zinc indium (comparative example 2) and aluminum zinc indium bismuth (specific example) alloy. Electrochemical impedance diagram; Figure 5(a)~(c) are the measurement results using constant current of 50, 100, and 150mA respectively.

It can be seen from Figure 4 that the aluminum alloy anode containing active elements can have a lower resistance value, and the aluminum alloy anode containing zinc, tin, indium, and bismuth active elements can have the lowest resistance value. In addition, it can be found from the results of Figure 3 and Figure 4(a)~(d) that the more holes the electrode produces after linear voltammetry (LSV) testing and the deeper they penetrate into the substrate, the greater the resistance and capacitance formed in Figure 4. The number of half turns increases (as shown in Figure 4(c) and Figure 4(d)), which also proves that the aluminum alloy anode of the present invention can form pores on the electrode surface through the dissolution of intermetallic compounds. The holes and cracks will cause the oxide layer on the electrode surface to peel off, and the electrode can be repeatedly activated, so it can have a lower impedance. As can be seen from Figure 5, when the output current is small (Figure 5(a), 50mA), the applied potential of the aluminum anode will gradually increase over time, indicating that the oxide layer on the surface of the aluminum anode will thicken over time, making Increased barriers to electron movement lead to electrode passivation. An aluminum alloy anode (specific example) containing zinc, tin, indium, and bismuth can maintain the lowest and stable performance over time under different current conditions (Figure 5(b) 100mA, Figure 5(c) 100mA) The potential shows that the aluminum alloy anode has excellent current output stability because the surface can be continuously activated.

Since the general aluminum alloy anode will gradually form an oxide layer on its surface during the reaction process, causing electrode passivation, therefore, in this case, zinc, tin, indium, bismuth and other elements are added to aluminum at the same time, and this composite material is used to make aluminum The intermetallic compounds containing active elements of indium and bismuth produced during the heat treatment of the alloy anode have low compatibility with the aluminum matrix and have better solubility characteristics, allowing the intermetallic compounds to precipitate along the grain boundaries of the aluminum alloy grains. Continuous chain and granular distribution of precipitates are formed at and near the grain boundaries. Since these active elements have greater activity, during the electrochemical reaction process, these active elements can be used to promote the dissolution of the aluminum matrix, and further pass through the intermetallic compound (precipitate) containing indium and bismuth with higher Due to the solubility characteristics, the intermetallic compound dissolves from the aluminum alloy anode during the electrochemical reaction process, and can produce holes on the surface of the aluminum alloy anode. At the same time, the indium ions and bismuth ions generated after dissolution can further damage the aluminum alloy anode. The aluminum oxide on the surface is converted into soluble aluminum hydroxide, causing the oxide layer to self-contain The surface of the aluminum alloy anode is peeled off to restore the activity of the aluminum alloy anode, and the dissolved indium ions and bismuth ions can be replaced by aluminum and deposited on the surface of the aluminum alloy anode, thereby reactivating the aluminum alloy anode and maintaining output. The stability of the current can be more widely used in electrodes of electrochemical batteries, so the purpose of the present invention can indeed be achieved.

However, the above are only experimental examples of the present invention. They cannot be used to limit the scope of the present invention. All simple equivalent changes and modifications made based on the patent scope of the present invention and the contents of the patent specification are still within the scope of the present invention. within the scope covered by the patent of this invention.

Claims (9)

A method for making an aluminum alloy anode for a chemical battery, including the following preparation steps: providing an aluminum alloy composite material. Based on a weight percentage of the aluminum alloy composite material of 100wt%, the aluminum alloy composite material contains: 3~10wt% zinc , 0.05~5wt% tin, 0.05~5wt% indium, 0.05~5wt% bismuth, and the balance aluminum; in the heat treatment step, the aluminum alloy composite material is melted and mixed at a temperature of 1000~1200°C, and Flushing the molten aluminum alloy composite material with inert gas for at least 10 minutes and maintaining the temperature for a predetermined time; and a molding step, cooling the temperature of the aluminum alloy composite material after the heat treatment step to 700~800°C, and using the mold The aluminum alloy anode is produced by casting. The production method as described in claim 1, wherein the zinc content is between 5 and 10 wt%. The production method as described in claim 1, wherein the tin content is between 0.1~3.0wt%. The production method as described in claim 1, wherein the content of indium is between 0.1~3.0wt%. The production method as described in claim 4, wherein the content of indium is between 0.1~1.5wt%. The production method as described in claim 1, wherein the bismuth content is between 0.1~3.0wt%. The production method as described in claim 6, wherein the bismuth content is between 0.1~1.5wt%. An aluminum alloy anode made by the manufacturing method of claim 1, wherein the aluminum alloy anode has precipitates precipitated along the grain boundaries of the grains, and the precipitates contain aluminum (Al)-indium (In) -An intermetallic compound composed of bismuth (Bi). The aluminum alloy anode according to claim 8, wherein the precipitates are in the form of chains and granules.