Alkaline aluminum-air battery composite electrolyte, additive and preparation method thereof

Abstract

The present invention relates to an alkaline aluminum-air battery composite electrolyte and its additive and preparation method, the composite electrolyte includes a sodium hydroxide solution and the additive, the rest is water, the additive includes 8-hydroxyquinoline and decyl glucoside, the concentration of the sodium hydroxide solution is 2-7M, the concentration of the 8-hydroxyquinoline is 2-10mM, the concentration of the decyl glucoside is 1-4mM, preferably the concentration of 8-hydroxyquinoline is 10mM, and the effect is best when the concentration of decyl glucoside is 3mM; the preparation method is specifically: preparing a sodium hydroxide solution, cooling, adding 8-hydroxyquinoline, ultrasonically dissolving it completely, then adding decyl glucoside, stirring and mixing evenly. Compared with the prior art, the present invention enhances the corrosion inhibition effect of the additive through a synergistic effect, improves the utilization rate of the aluminum anode, and after electrochemical testing, the best corrosion inhibition efficiency of the present invention can reach 85.3%, and the anode utilization rate is increased to 92.5%. The sources of the components in the additive are wide and non-toxic, suitable for large-scale use, and environmentally friendly.

Description

Technical Field

[0001] The present invention belongs to the technical field of aluminum-air batteries and relates to an alkaline aluminum-air battery composite electrolyte, an additive thereof and a preparation method thereof. Background Art

[0002] Aluminum-air batteries are high-energy-density fuel cells considered a promising new green power source due to their large capacity, high specific energy, low cost, stable discharge, and low pollution. Research on aluminum-air batteries dates back to 1962, when S. Zaromb et al. conducted the first feasibility study of an aluminum-air battery system. Furthermore, breakthroughs in key aluminum-air battery material technology have been achieved by Alcoa of the United States and Phinergy of Israel. Their jointly developed aluminum-air battery-powered vehicle boasts a range of nearly 1,000 miles, significantly impacting the commercial application of aluminum-air batteries.

[0003] Admittedly, aluminum-air batteries have immeasurable development prospects and research value. However, aluminum is highly susceptible to self-corrosion due to hydrogen evolution in alkaline media, resulting in reduced Coulombic efficiency and affecting battery life. Currently, the most commonly used methods to address hydrogen evolution corrosion in aluminum electrodes include using aluminum alloys instead of pure aluminum as anodes, using gel electrolytes instead of aqueous electrolytes, and adding additives to the electrolyte. Compared to other technologies, the use of additives offers advantages such as lower cost, smaller addition amounts with more pronounced effects, and abundant sources, making them an ideal protection method.

[0004] Research on aluminum-air battery electrolyte additives has a history of nearly a century. Different types of additives have different defects. For example, single-type electrolyte additives have limited corrosion inhibition effects and will inhibit anode activity. Composite additives often have complex ingredients and cumbersome processes. The preparation process of certain ingredients may produce pollutants, further limiting their application.

[0005] The Chinese invention patent application with publication number CN201911228140.3 reported that quinoline-8-sulfonic acid and calcium oxide were used as compound additives for alkaline aluminum-air battery electrolytes. These additives not only effectively inhibited the self-corrosion of hydrogen evolution at the aluminum-air battery anode, but also improved the battery's discharge performance. However, the anode utilization rate needed to be further improved. The Chinese invention patent application with publication number CN201910350420.5 reported that alkyl glycosides and tin sources were used as compound additives for alkaline aluminum-air battery electrolytes. The compound additives were compounded with surfactants and inorganic compounds, which had an inhibitory effect on hydrogen evolution corrosion at the aluminum anode. However, the amount of inorganic substances used was large, and the anode utilization rate needed to be further improved. The Chinese invention patent application with publication number CN201811221619.X reported that 8-hydroxyquinoline and zinc oxide were used as compound additives for alkaline aluminum-air battery electrolytes. However, the precipitated zinc easily fell off the surface of the aluminum anode, so its corrosion inhibition effect was limited. Application publication number CN202010181154.0 discloses a high-concentration alkaline electrolyte for aluminum-air batteries. By adding high-concentration potassium salt, the free water molecules are reduced, the activity of water molecules is inhibited, and the activation energy of the hydrogen evolution reaction is increased, thereby effectively inhibiting the self-corrosion of the aluminum negative electrode. However, this method requires the addition of a large amount of sodium and potassium salts, the electrolyte cost is high, and the high-concentration electrolyte has high viscosity and greatly reduced conductivity, which is not conducive to the electrochemical performance of the aluminum anode. Summary of the Invention

[0006] The purpose of the present invention is to provide an alkaline aluminum-air battery composite electrolyte, its additive and preparation method in order to overcome the defects of the above-mentioned prior art. The alkaline aluminum-air battery composite electrolyte of the present invention has a simple formula, is easy to operate and is low in price. At the same time, it can inhibit the hydrogen evolution corrosion of the aluminum anode and significantly improve the performance of the aluminum-air battery, improve the anode efficiency, and is conducive to promoting the practical application of aluminum-air batteries.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] One of the technical solutions of the present invention is to provide an additive for an alkaline aluminum-air battery composite electrolyte, wherein the additive comprises 8-hydroxyquinoline and decyl glucoside.

[0009] The additive has a fluorescence effect, and the fluorescence spectrum can be used as a detection method to explore the corrosion inhibition performance.

[0010] The present invention innovatively discovered that 8-hydroxyquinoline and decyl glucoside have a good synergistic effect as electrolyte corrosion inhibitor additives. On the one hand, the hydroxyl (-OH) and ether (COC) polar groups in decyl glucoside can be adsorbed on the metal surface, and on the other hand, its micelles can connect and coat 8-hydroxyquinoline, making the complex formed with the metal more stable. The non-polar groups form a hydrophobic layer that can further protect the metal. The combination of the two can effectively and synergistically reduce the hydrogen evolution self-corrosion rate of the aluminum anode, while also improving the electrochemical performance of the aluminum-air battery and increasing the anode utilization rate.

[0011] The present invention found that when the concentration of decyl glucoside is too high, the corrosion inhibition efficiency decreases. This is because excessive decyl glucoside forms micelles, reducing its adsorption on the electrode surface. At the same time, the aggregated micelles enhance the coating ability of 8-hydroxyquinoline, which is also detrimental to the adsorption of 8-hydroxyquinoline on the aluminum electrode surface. Therefore, controlling the concentration of decyl glucoside can help further enhance the synergistic effect of the two.

[0012] Furthermore, in the composite electrolyte, the concentration of the 8-hydroxyquinoline is 2-10 mM, and the concentration of the decyl glucoside is 1-4 mM.

[0013] Furthermore, in the composite electrolyte, the concentration of the 8-hydroxyquinoline is 10 mM, and the concentration of the decyl glucoside is 3 mM.

[0014] One of the technical solutions of the present invention is to provide an alkaline aluminum-air battery composite electrolyte, which includes a sodium hydroxide solution and the additives, and the rest is water.

[0015] Furthermore, the concentration of the sodium hydroxide solution is 2-7M.

[0016] One of the technical solutions of the present invention is to provide a method for preparing an alkaline aluminum-air battery composite electrolyte. The preparation method specifically comprises: preparing a sodium hydroxide solution, cooling it, adding 8-hydroxyquinoline, and ultrasonically dissolving it completely, then adding decyl glucoside, and stirring and mixing it evenly.

[0017] Furthermore, the cooling temperature is room temperature.

[0018] Furthermore, the ultrasonic treatment time is 5-20 minutes.

[0019] Furthermore, the stirring time is 1-5 minutes.

[0020] An alkaline aluminum-air battery adopts the composite electrolyte.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] (1) The components of the present invention are simple in composition, low in cost, safe and meet environmental protection requirements, avoiding the use of rare heavy metal ions and harmful compounds that pollute the environment;

[0023] (2) The hydroxyl and ether polar groups in the decyl glucoside of the present invention can be adsorbed on the metal surface on the one hand, and on the other hand, the micelles thereof can be connected and coated with 8-hydroxyquinoline, making the complex formed between the decyl glucoside and the metal more stable; the non-polar groups form a hydrophobic layer, which can further protect the metal; the combination of the two can not only significantly reduce the hydrogen evolution self-corrosion rate of the aluminum anode, but also improve the discharge performance of the aluminum anode. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a polarization curve test diagram of AA5052 aluminum alloy in Example 1 of the present invention in a sodium hydroxide solution containing different concentrations of 8-hydroxyquinoline and decyl glucoside additives;

[0025] Figure 2 This is an electrochemical impedance spectroscopy test graph of AA5052 aluminum alloy in Example 1 of the present invention in a sodium hydroxide solution containing different concentrations of 8-hydroxyquinoline and decyl glucoside additives;

[0026] Figure 3 1 is a constant current discharge curve of AA5052 aluminum alloy in Example 2 of the present invention in a sodium hydroxide solution containing different concentrations of 8-hydroxyquinoline and decyl glucoside additives;

[0027] Figure 4 1 is an interval discharge curve diagram of AA5052 aluminum alloy in Example 2 of the present invention at a constant current density in a sodium hydroxide solution containing 8-hydroxyquinoline and decyl glucoside additives at different concentrations;

[0028] Figure 5 This is a scanning electron microscope (SEM) image of the AA5052 aluminum alloy after being immersed in a sodium hydroxide solution in Example 2 of the present invention;

[0029] Figure 6 This is a scanning electron microscope image of the AA5052 aluminum alloy after being immersed in a sodium hydroxide solution containing a single 8-hydroxyquinoline additive in Example 2 of the present invention;

[0030] Figure 7 This is a scanning electron microscope image of the AA5052 aluminum alloy after being immersed in a sodium hydroxide solution containing a single decyl glucoside additive in Example 2 of the present invention;

[0031] Figure 8 This is a scanning electron microscope image of the AA5052 aluminum alloy in Example 2 of the present invention after being immersed in a sodium hydroxide solution containing a compounded 8-hydroxyquinoline and decyl glucoside additive;

[0032] Figure 9 The UV spectra of the AA5052 aluminum alloy in Example 3 of the present invention after discharge at a constant current density in a sodium hydroxide solution containing 8-hydroxyquinoline and decyl glucoside additives at different concentrations are shown;

[0033] Figure 10 1 is a fluorescence spectrum of the electrode surface of the AA5052 aluminum alloy in Example 3 of the present invention after discharge at a constant current density in a sodium hydroxide solution containing 8-hydroxyquinoline and decyl glucoside additives at different concentrations. DETAILED DESCRIPTION

[0034] The present invention is described in detail below with reference to specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0035] Unless otherwise specified, the equipment used in the following examples are all conventional equipment in the art; the reagents used are all commercially available products or prepared by conventional methods in the art unless otherwise specified. Anything not described in detail in the following examples can be achieved by conventional experimental means in the art.

[0036] Electrochemical experiments were performed using a three-electrode system, with a platinum electrode as the auxiliary electrode and a saturated calomel electrode (SCE) as the reference electrode. The working electrode was sealed with epoxy resin, leaving 1 cm exposed. 2 The working surface was then sanded (to 2000 grit), ultrasonically degreased with alcohol, rinsed with deionized water, and air-dried. Electrochemical tests were performed on a Solartron 1287 / 1260 Electrochemical Interface test system. The polarization curve scan rate was 1 mV / min, and the scan range was ±300 mV relative to the open circuit potential. The frequency of the electrochemical impedance spectroscopy test was 10 -2 -10 5 Hz, and the impedance measurement signal amplitude is a 5mV sine wave.

[0037] Example 1:

[0038] An additive for an alkaline aluminum-air battery composite electrolyte comprises 8-hydroxyquinoline and decyl glucoside. In the composite electrolyte, the concentration of 8-hydroxyquinoline is 10 mM, and the concentration of decyl glucoside is 1-4 mM.

[0039] An alkaline aluminum-air battery composite electrolyte comprises sodium hydroxide, 8-hydroxyquinoline and decyl glucoside, wherein the concentration of sodium hydroxide is 4M, the concentration of 8-hydroxyquinoline is 10mM, and the concentrations of decyl glucoside are 1mM, 2mM, 3mM and 4mM.

[0040] A method for preparing an alkaline aluminum-air battery composite electrolyte comprises the following steps:

[0041] (1) Prepare 200 mL of 4 M sodium hydroxide aqueous solution, cool to room temperature, and record as sample 1;

[0042] (2) Prepare four more samples of sample 1, add 8-hydroxyquinoline to a concentration of 10 mM, sonicate for 10 min to completely dissolve, then add decyl glucoside to a concentration of 1 mM, 2 mM, 3 mM, and 4 mM, respectively. Stir for 1 min to mix. These samples are recorded as samples 2, 3, 4, and 5, respectively.

[0043] An electrochemical experiment of an alkaline aluminum-air battery composite electrolyte includes the following steps:

[0044] The pretreated AA5052 aluminum alloy electrodes were placed in the electrolyte samples 1 to 5 and the open circuit potential was first tested for 10 minutes to stabilize the potential of the electrodes. Polarization curve tests and AC impedance tests were then performed.

[0045] Corrosion inhibition efficiency (η i %) is calculated according to the following formula:

[0046]

[0047] Among them, i corr and i corr(inh) The corrosion current density of AA5052 aluminum alloy is shown in Figure 2, with and without corrosion inhibitor treatment.

[0048] The fitting parameters of the polarization curves of the aluminum electrode in sodium hydroxide solutions containing different concentrations of 8-hydroxyquinoline (8-HQ) and decyl glucoside (DG) additives are shown in Table 1.

[0049] Table 1 Polarization curve fitting parameters of AA5052 aluminum alloy in sodium hydroxide solution containing different concentrations of 8-hydroxyquinoline and decyl glucoside additives

[0050]

[0051] As shown in Table 1, the corrosion inhibition rate of the composite additive on the aluminum electrode first increases with the increase of the decyl glucoside concentration. When the decyl glucoside concentration is 3 mM, the corrosion inhibition rate is the largest, and the optimal corrosion inhibition rate is 85.3%. Therefore, the present invention preferably uses 3 mM decyl glucoside, and the composite additive at this concentration has the best corrosion inhibition effect on aluminum.

[0052] like Figure 1As shown in the graph, the cathode and anodic corrosion current densities of the aluminum electrode in the electrolyte containing the composite additive decreased, and the potential shifted negatively. This indicates that the 8-hydroxyquinoline and decyl glucoside composite additive is a mixed corrosion inhibitor. The composite additive primarily reduces hydrogen evolution by adsorbing on the active sites of the aluminum electrode.

[0053] like Figure 2 As shown, the aluminum electrode exhibits the smallest capacitive arc in the blank solution. This arc increases with the addition of the composite additive at varying concentrations, demonstrating that the composite additive effectively inhibits corrosion. The capacitive arc is greatest when the concentration of 8-hydroxyquinoline is 10 mM and the concentration of decyl glucoside is 3 mM, demonstrating that the composite additive exhibits the best protective effect at these concentrations. Therefore, the preferred concentration of 8-hydroxyquinoline in the present invention is 10 mM and the concentration of decyl glucoside is 3 mM.

[0054] Example 2:

[0055] An additive for an alkaline aluminum-air battery composite electrolyte comprises 8-hydroxyquinoline and decyl glucoside. In the composite electrolyte, the concentration of 8-hydroxyquinoline is 10 mM, and the concentration of decyl glucoside is 3 mM.

[0056] An alkaline aluminum-air battery composite electrolyte comprises sodium hydroxide, 8-hydroxyquinoline and decyl glucoside, wherein the concentration of sodium hydroxide is 4M, the concentration of 8-hydroxyquinoline is 10mM, and the concentration of decyl glucoside is 3mM.

[0057] A method for preparing an alkaline aluminum-air battery composite electrolyte comprises the following steps:

[0058] (1) Prepare 200 mL of 4 M sodium hydroxide aqueous solution, cool to room temperature, and record as sample 6;

[0059] (2) Prepare another portion of sample 6 and add 8-hydroxyquinoline to a concentration of 10 mM. Ultrasonicate for 10 min to completely dissolve the mixture. This is designated as sample 7.

[0060] (3) Prepare another portion of sample 6 and add decyl glucoside to a concentration of 3 mM. Stir for 1 min to mix thoroughly. This is recorded as sample 8.

[0061] (4) Prepare another portion of sample 7 and add decyl glucoside to make the concentration reach 3 mM. Stir for 1 min to mix evenly. This is recorded as sample 9.

[0062] A performance test of an alkaline aluminum-air battery containing the composite electrolyte comprises the following steps:

[0063] The electrochemical workstation was used to test the constant current discharge of the pretreated AA5052 aluminum alloy anode in the electrolyte samples 6 to 9 prepared in this embodiment. The open circuit potential was first tested for 1 hour, and then the constant current discharge was tested for 2 hours. The discharge current density was controlled to be 20 mA cm -2 .

[0064] like Figure 3 As shown in the figure, after adding the compound additives 8-hydroxyquinoline and decyl glucoside, a platform appears and the discharge point is more negative, indicating that the addition of the compound additives significantly improves the discharge performance.

[0065] The electrochemical workstation was used to test the interval discharge of the pretreated AA5052 aluminum alloy anode in the electrolyte samples 6 to 9 prepared in this embodiment. The open circuit potential was tested for 1 hour, and then the constant current discharge was tested for 1 hour. The discharge current density was controlled to be 20 mA cm -2 , and cycle in sequence.

[0066] like Figure 4 As shown in the figure, after adding the compound additives 8-hydroxyquinoline and decyl glucoside, the aluminum alloy anode has better discharge performance over a long period of time, and the addition of the compound additives significantly improves the discharge performance.

[0067] The anode utilization rate is calculated according to the following formula:

[0068]

[0069] Among them, U a is the anode utilization rate (%), I is the discharge current (A), T is the discharge time (s), Δm is the weight loss of aluminum alloy (g), F is the Faraday constant (96485C·mol -1 ).

[0070] The anode utilization rate of aluminum alloy in sodium hydroxide solution containing different additives is shown in Table 2.

[0071] Table 2 Anode utilization of AA5052 aluminum alloy in sodium hydroxide solution containing different additives

[0072]

[0073] As shown in Table 2, after adding the compound additives 8-hydroxyquinoline and decyl glucoside, the anode utilization rate increased to 92.5%.

[0074] AA5052 aluminum alloy was immersed in the electrolyte samples 6 to 9 prepared in this example for 1 hour, after which the samples were taken out and dried, and then characterized by scanning electron microscopy.

[0075] like Figures 5 to 8As shown in the figure, after 8-hydroxyquinoline and decyl glucoside are compounded, a denser and more complete protective film is formed on the surface of the aluminum alloy anode.

[0076] The element distribution of aluminum alloy in the AH region in sodium hydroxide solution containing different additives is shown in Table 3.

[0077] Table 3 Element content of AA5052 aluminum alloy in sodium hydroxide solution containing different additives

[0078]

[0079] As shown in Table 3, when decyl glucoside was present, the amount of nitrogen detected on the aluminum electrode surface increased, which indicated that the presence of decyl glucoside was beneficial to the adsorption of 8-hydroxyquinoline on the aluminum surface.

[0080] Example 3:

[0081] An additive for an alkaline aluminum-air battery composite electrolyte comprises 8-hydroxyquinoline and decyl glucoside. In the composite electrolyte, the concentration of 8-hydroxyquinoline is 2 mM, and the concentration of decyl glucoside is 3 mM.

[0082] An alkaline aluminum-air battery composite electrolyte comprises sodium hydroxide, 8-hydroxyquinoline and decyl glucoside, wherein the concentration of sodium hydroxide is 4M, the concentration of 8-hydroxyquinoline is 2mM, and the concentration of decyl glucoside is 3mM.

[0083] A method for preparing an alkaline aluminum-air battery composite electrolyte comprises the following steps:

[0084] (1) Prepare 200 mL of 4 M sodium hydroxide aqueous solution, cool to room temperature, add 8-hydroxyquinoline to a concentration of 2 mM, and sonicate for 10 min to completely dissolve it. This is referred to as sample 10.

[0085] (2) Prepare another portion of sample 10 and add decyl glucoside to a concentration of 3 mM. Stir for 1 min to mix thoroughly. This portion is recorded as sample 11.

[0086] An electrochemical experiment of an alkaline aluminum-air battery composite electrolyte includes the following steps:

[0087] The electrochemical workstation was used to test the constant current discharge of the pretreated AA5052 aluminum alloy anode in the electrolyte samples 10 and 11 prepared in this embodiment. The test time was 1 h, and the discharge current density was controlled to be 20 mA cm -2 The discharged electrolyte was then subjected to UV testing.

[0088] like Figure 9As shown, after the discharge test, the UV absorption peak intensity of the electrolyte solution decreases, indicating that the additive is adsorbed on the electrode surface and the amount of the additive in the solution decreases.

[0089] Conduct fluorescence test on the aluminum alloy anode after discharge.

[0090] like Figure 10 As shown in the figure, the surface of the aluminum alloy anode has a strong fluorescence effect, and the presence of decyl glucoside increases its fluorescence intensity on the one hand, and shifts the fluorescence emission wavelength to the left on the other hand, indicating that the decyl glucoside micelles can be jointly coated with 8-hydroxyquinoline through the polar head group, making its adsorption of aluminum more stable.

[0091] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. An alkaline aluminum-air battery composite electrolyte, characterized in that: The composite electrolyte comprises a sodium hydroxide solution and an additive, and the remainder is water; The additives include 8-hydroxyquinoline and decyl glucoside; In the composite electrolyte, the concentration of the 8-hydroxyquinoline is 2-10 mM, and the concentration of the decyl glucoside is 1-4 mM.

2. The alkaline aluminum-air battery composite electrolyte according to claim 1, characterized in that: In the composite electrolyte, the concentration of the 8-hydroxyquinoline is 10 mM, and the concentration of the decyl glucoside is 3 mM.

3. The alkaline aluminum-air battery composite electrolyte according to claim 1, characterized in that: The concentration of the sodium hydroxide solution is 2-7 M.

4. A method for preparing an alkaline aluminum-air battery composite electrolyte according to any one of claims 1 to 3, characterized in that: The preparation method specifically comprises the following steps: preparing a sodium hydroxide solution, cooling the solution, adding 8-hydroxyquinoline, completely dissolving the solution through ultrasonication, adding decyl glucoside, and stirring to mix the solution evenly.

5. The method for preparing a composite electrolyte for an alkaline aluminum-air battery according to claim 4, characterized in that: The cooling is cooling to room temperature.

6. The method for preparing a composite electrolyte for an alkaline aluminum-air battery according to claim 4, wherein: The ultrasonic time is 5-20 min.

7. The method for preparing a composite electrolyte for an alkaline aluminum-air battery according to claim 4, characterized in that: The stirring time is 1-5 min.

8. An alkaline aluminum-air battery, characterized in that: The alkaline aluminum-air battery uses the composite electrolyte as described in any one of claims 1 to 3.

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