CN114759294A - Electrolyte for efficiently regulating and controlling dissolution behavior of magnesium anode and preparation method thereof - Google Patents

Abstract

An electrolyte for efficiently regulating the dissolution behavior of magnesium anodes and a preparation method thereof. The electrolyte is a mixed aqueous solution of sodium chloride and 5-sulfosalicylic acid, wherein the concentration of sodium chloride is 0.5-0.7M, and the concentration of 5-sulfosalicylic acid is 0.5-0.7M. The concentration of salicylic acid is 0.01～0.1M, and pH value=7.0±0.2; the preparation method is: (1) mixing sodium chloride and 5-sulfosalicylic acid to prepare a mixed material; (2) deionizing Water is added to the mixture and stirred to form a transparent solution; (3) the pH value is adjusted to 7.0±0.2 to prepare an electrolyte for efficiently regulating the dissolution behavior of the magnesium anode. The invention can adjust the solute ratio to improve the electrochemical behavior of the magnesium alloy, the electrolyte components are easy to obtain, the process for processing and preparing the electrolyte is simple, it can act on the seawater environment, and it is suitable for three different discharge current densities and environmental protection. Magnesium-air battery performance.

Description

Electrolyte for efficiently regulating the dissolution behavior of magnesium anode and preparation method thereof

technical field

The invention relates to an electrolyte for efficiently regulating the dissolution behavior of magnesium anodes and a preparation method thereof, and belongs to the technical field of electrolytes for magnesium-air batteries.

Background technique

Energy issues will always be a hot issue in the 21st century. With the development of science and technology, people's demand for and use of energy has increased significantly. Fossil energy such as coal and petroleum is currently consumed seriously and is not renewable. After combustion, harmful gases such as SO ₂ and CO ₂ will be produced. When SO ₂ gas enters the atmosphere, acid rain will occur, and CO ₂ gas will cause the greenhouse effect phenomenon, resulting in extreme climate change such as sea level rise, which will greatly affect people's production and life; therefore, for new energy (battery) ) is particularly important.

Because of its high theoretical voltage and electric capacity, magnesium-air batteries are expected to replace fossil energy with the deepening of the research process. However, magnesium-air batteries also have application limitations due to their own characteristics. For example, the anode has poor corrosion resistance in aqueous solution and shows a low anode utilization rate. After the anode is discharged, the discharge products are easily deposited on the surface of the anode, and the use of oxygen reaction in the air cathode to conduct charge conduction is hindered, which eventually leads to a lower discharge voltage of the actual magnesium-air battery. Therefore, it is of great research value to improve the discharge performance of magnesium-air batteries.

For the improvement of the performance of the magnesium-air battery, the main purpose is to improve the performance of the anode part of the magnesium-air battery. There are usually two ways to improve anode performance, namely, improving anode composition by means of extrusion and alloying, and adjusting electrolyte composition to improve anode performance. Adjust the composition of the electrolyte, improve the corrosion resistance of the magnesium anode or accelerate the shedding of the discharge products on the anode surface, so as to maintain the transfer process of the surface charge on the magnesium surface during the discharge process to a greater extent, and ensure the stability of the discharge potential under long-term cycles and high anode utilization. and specific capacity. The method of using electrolyte to improve anode discharge performance and anode corrosion resistance is low in cost and simple in processing technology. Compared with the traditional method of improving anode composition, it has greater significance in practical production and application.

Although there are many advantages by improving or regulating the composition of the electrolyte, the invention of the electrolyte for magnesium-air batteries is very few at present, and it has not received widespread attention. The patent with the application number of 201911073752.X proposes a method for improving anode performance with a plasticizer, a first polymer monomer, a second polymer monomer, an initiator, an inorganic salt filler, and a composite corrosion inhibitor; this method can Improve the corrosion resistance of magnesium alloys in solution. However, excessive addition of corrosion inhibitor reduces the contact area between the anode and the electrolyte, which is not conducive to maintaining a low and stable discharge potential. In addition, the electrolyte provided by the invention has complex components, and requires complicated processes such as stirring, heating treatment in a muffle furnace, grinding powder, and preparing a gel electrolyte, which brings inconvenience to industrial production and large-scale application.

The patent with the application number of 202110301670.7 proposes a method for improving the battery performance with the electrolyte of potassium nitrate and salicylic acid compounds, which improves the discharge performance of the AZ31 anode at 2.5mA cm ^-2 . The patent shows that the AZ31 anode is at 0.05mol/mol/ The mixed electrolyte of L potassium nitrate and 0.1mol/L sodium salicylate has the best discharge performance and the lowest discharge potential, but it is still only around -1.0V, which is far lower than the theoretical value. The invention only provides the effect of the electrolyte on the anode at a current density of 2.5 mA cm ^-2 , but does not provide the effect of the electrolyte on the performance of the anode at a high current density. Magnesium-air batteries are mainly used in seawater environment, but the invention does not take into account the influence of sodium chloride solution on the anode, and there are major defects.

SUMMARY OF THE INVENTION

Aiming at the problems of poor corrosion resistance of the anode in the magnesium-air battery, voltage hysteresis caused by the accumulation of discharge products on the anode surface during the discharge process, and the like, the invention provides an electrolyte for efficiently regulating the dissolution behavior of the magnesium anode and a preparation method thereof, and effectively improves the resistance of the magnesium anode. corrosion behavior and improved discharge performance.

The electrolyte for efficiently regulating the dissolution behavior of magnesium anode in the present invention is a mixed aqueous solution of sodium chloride and 5-sulfosalicylic acid, wherein the concentration of sodium chloride is 0.5-0.7M, and the concentration of 5-sulfosalicylic acid is 0.01～0.1M, pH=7.0±0.2.

The preparation method of the electrolytic solution for efficiently regulating and controlling the dissolution behavior of magnesium anode of the present invention is carried out according to the following steps:

(1) sodium chloride and 5-sulfosalicylic acid are mixed to make mixed material;

(2) deionized water is added to the mixture, and then all the materials are stirred until a transparent solution is formed;

(3) The pH value of the transparent solution is adjusted with sodium hydroxide or hydrochloric acid to pH value=7.0±0.2, so as to prepare an electrolyte for efficiently regulating the dissolution behavior of magnesium anode.

In the above-mentioned step (2), when adding deionized water, the mixture material is placed in a container, and the deionized water is poured along the inner wall of the container.

In the above-mentioned step (2), the stirring speed is 100-150 rpm.

In the above-mentioned step (3), the pH-conductivity meter is used to monitor the pH value.

The using method of the electrolyte of the present invention for efficiently regulating and controlling the dissolving behavior of magnesium anode is:

The magnesium anode is placed in an electrolyte that can efficiently regulate the dissolution behavior of the magnesium anode to form a magnesium-air battery; the magnesium anode is energized through a power source.

In the above method of use, the material of the magnesium anode is pure magnesium with a purity of ≥99.5%.

In the above-mentioned usage method, the current density of the energization is 2.5 to 10 mA·cm ⁻² .

In the above method of use, the cathode is an air cathode.

The electrolyte for high-efficiency adjustment of magnesium anode provided by the present invention introduces sodium chloride and strong complexing agent 5-sulfosalicylic acid for the first time, and the corrosion resistance and discharge performance of pure magnesium can be improved by adjusting the ratio of the two; It has the characteristics of simple acquisition, simple processing technology, low cost, green environmental protection and suitable for marine environment.

The magnesium anode shows excellent corrosion resistance in the electrolyte provided by the present invention; in the state of no current application, the corrosion inhibition efficiency reaches 66.7%; the average discharge potential reaches -1.83V; the potential drops significantly, compared with the sodium chloride solution reduced by about 200mV.

The electrolyte provided by the present invention significantly improves the utilization efficiency of the magnesium anode; the discharge specific capacity of the magnesium anode is greatly improved in the electrolyte provided by the present invention.

Compared with the original invention, the present invention successfully prepares an electrolyte for efficiently regulating the dissolution behavior of magnesium anode, and has the following advantages: the ratio of solute can be regulated to improve the electrochemical behavior of magnesium alloy, the electrolyte composition is easy to obtain, and the process for preparing the electrolyte is simple. , Can act in seawater environment, adapt to three different discharge current densities and environmental protection characteristics; can well improve the performance of magnesium-air batteries.

Description of drawings

Fig. 1 is the hydrogen evolution curve diagram of magnesium anode after soaking for two days in the comparative example and the embodiment of the present invention;

2 is a graph of the average discharge potential of the magnesium anode at 2.5 mA cm ⁻² in the comparative example and the embodiment of the present invention;

3 is a graph of the average discharge potential of the magnesium anode at 5 mA·cm ⁻² in the comparative example and the embodiment of the present invention;

4 is a graph of the average discharge potential of the magnesium anode at 10 mA·cm ⁻² in the comparative example and the embodiment of the present invention;

5 is a graph showing the utilization efficiency of magnesium anodes under different current densities in the comparative example and the embodiment of the present invention;

FIG. 6 is a graph showing the discharge specific capacity of the magnesium anode at different current densities in the comparative example and the embodiment of the present invention.

Detailed ways

The embodiments provided by the present invention will be further described below, and the following embodiments are hereby proposed only to illustrate the implementation method of the present invention. A skilled operator can make appropriate improvements to the implementation method, and the implementation method is not limited to the examples provided in the present invention.

Comparative ratio

Add deionized water to sodium chloride, and then stir all the materials at a stirring speed of 120 rpm until a transparent solution is formed; use a pH-conductivity meter to monitor the pH value of 7.0 ± 0.2; make a comparative electrolyte;

The magnesium anode is placed in a comparative electrolyte to form a magnesium-air battery; the magnesium anode is energized through a power source; the material of the magnesium anode is pure magnesium with a purity of ≥99.5%; the current density of the electrification is 2.5-10 mA·cm ^-2 ; the cathode is is the air cathode;

The magnesium anode was soaked in the comparative electrolyte for two days, and the area of the tested magnesium anode was 900cm ^-2 , and the total amount of hydrogen evolution was finally obtained; the discharge current densities were 2.5, 5 and 10mA·cm ^-2 respectively, and the discharge time was 10h; The weight loss of the anode after the discharge in Comparative Example 1 was completed, and the anode utilization efficiency and discharge specific capacity were obtained;

The amount of hydrogen evolution after soaking for two days is shown in Figure 1; it can be seen from Figure 1 that the corrosion resistance of the magnesium anode in Comparative Example 1 is poor, and the discharge potential of the anode under three discharge current densities is shown in Figures 2 to 4. The potential is higher, which indicates that after the anode is discharged, a large number of discharge products are deposited on the surface of the anode, and the contact area between the anode and the electrolyte is drastically reduced; The utilization efficiency and discharge specific capacity after completion are low, which means that the anode has a large magnesium matrix shedding phenomenon during the discharge process, which is not conducive to improving the discharge performance of the magnesium anode.

Example 1

In the electrolyte for efficiently regulating the dissolution behavior of magnesium anode, the concentration of sodium chloride is 0.62M, and the concentration of 5-sulfosalicylic acid is 0.01M;

Mix sodium chloride and 5-sulfosalicylic acid to prepare a mixture;

Add deionized water to the mixture, and then stir all the materials until a transparent solution is formed; when adding deionized water, place the mixture in a container, and pour the deionized water along the inner wall of the container; the stirring speed is 100～150rpm;

The pH value of the transparent solution is adjusted with sodium hydroxide or hydrochloric acid, and the pH value is monitored with a pH-conductivity meter until the pH value is 7.0±0.2, and an electrolyte solution for efficiently regulating the dissolution behavior of magnesium anode is prepared.

The method of use is:

The magnesium anode is placed in an electrolyte that efficiently regulates the dissolution behavior of the magnesium anode to form a magnesium air battery; the magnesium anode is energized through a power source; the material of the magnesium anode is pure magnesium with a purity of ≥99.5%; 5 and 10 mA·cm ^-2 ; the cathode is an air cathode;

The magnesium anode was soaked for two days in an electrolyte that efficiently regulates the dissolution behavior of the magnesium anode, and the area of the magnesium anode tested was about 900 cm ² , and the total amount of hydrogen evolution was finally obtained to judge the corrosion resistance of the anode; the discharge of the magnesium anode in Example 1 The duration is 10 hours; the weight loss after the discharge of the magnesium anode is tested, and the anode utilization efficiency and discharge specific capacity are obtained;

The amount of hydrogen evolution is shown in Figure 1; the magnesium anode is chemically active, and it is easy to lose the outermost orbital electrons in aqueous solution to become Mg ²⁺ , and the two lost electrons are easy to be combined with H ₂ O in neutral solution or in acidic solution. Therefore, the amount of hydrogen evolution of the immersion for ² days can reflect the corrosion resistance of the anode very well; it can be seen from Figure 1 that the corrosion resistance of the magnesium anode is very good, after 48 hours, the amount of hydrogen evolution of the anode It is about 5 mL cm ^-2 , which is significantly lower than the hydrogen evolution amount of the anode in Comparative Example 1, indicating that it has the ability to well control the dissolution behavior of the anode and enhance the corrosion resistance of the anode.

Example 2

In the electrolyte for efficiently regulating the dissolution behavior of magnesium anode, the concentration of sodium chloride is 0.62M, and the concentration of 5-sulfosalicylic acid is 0.05M;

The preparation method is the same as in Example 1;

The use method and test method are the same as in Example 1, and the amount of hydrogen evolution after soaking for two days is shown in Figure 1; the chemical properties of the magnesium anode are active, and the total amount of hydrogen evolution is higher than that of Comparative Example 1, which shows that it is helpful to increase the electrochemical activity of the magnesium anode, Increasing the contact between the anode and the electrolyte is conducive to promoting the dissolution of the anode, so as to provide a lower discharge potential; it can be seen from Figures 2 to 4 that when the current density is 2.5 and 5 mA cm ^-2 , the average discharge potential of the anode is significantly lower than Comparative Example 1; the magnesium anode showed an average discharge potential of -1.82V (2.5mA cm ^-2 ) in Example 2; as can be seen from Figures 5 and 6, it was observed that the anode utilization efficiency and specific volume were effectively improved. The reason The strong complexing ability of the electrolyte inhibits the phenomenon that large pieces of undissolved magnesium matrix fall off into the electrolyte during the discharge process, thereby improving the anode utilization efficiency and specific volume; when the current density is 2.5mA cm ^-2 , compared with Comparative Example 1, the anode utilization efficiency is increased by 11.5%, and the specific capacity is increased by 255mAgh ^-1 .

Example 3

In the electrolyte for efficiently regulating the dissolution behavior of magnesium anode, the concentration of sodium chloride is 0.62M, and the concentration of 5-sulfosalicylic acid is 0.1M;

The preparation method is the same as in Example 1;

The use method and test method are the same as in Example 1, and the hydrogen evolution amount after soaking for two days reaches the highest, which is 27mL/cm ² ; this shows that the magnesium anode dissolves the fastest in the electrolyte, has the strongest electrochemical activity, and has the greatest discharge potential; fast The ability to dissolve the anode determines that the deposition of discharge products on the surface of the anode is extremely difficult; the probability of the appearance of Mg(OH) ₂ in the anode is the smallest during the discharge process, which facilitates the contact between the anode and the electrolyte and provides a low and stable discharge potential; the magnesium anode is in the electrolyte. The discharge potentials are shown in Figures 2-4; under three discharge current densities, the average discharge potential of the anode in the electrolyte is significantly lower than that of Comparative Example 1; the strong ability to complex magnesium anode greatly reduces the effect of discharge products on anode discharge. The hysteresis effect of the potential; when the current density is 2.5mA cm ^-2 , the average discharge potential of the magnesium anode in the electrolyte is about -1.84V, which is 200mV lower than the average discharge potential in Comparative Example 1; Figures 5 and 6 demonstrate that the electrolyte improves The anode utilization efficiency and specific volume were improved, and the electrolyte successfully suppressed the occurrence of large undissolved shedding, which maximized the anode utilization efficiency and specific volume; when the current density was 10mA cm ^-2 , the anode was utilized in the electrolyte. The efficiency reaches 57.6% and the specific capacity reaches 1286.5mAg h ^-1 .

Example 4

In the electrolyte for efficiently regulating the dissolution behavior of magnesium anode, the concentration of sodium chloride is 0.5M, and the concentration of 5-sulfosalicylic acid is 0.01M;

The preparation method is the same as in Example 1;

The use method is the same as that of Example 1.

Example 5

In the electrolyte for efficiently regulating the dissolution behavior of magnesium anode, the concentration of sodium chloride is 0.7M, and the concentration of 5-sulfosalicylic acid is 0.01M;

The preparation method is the same as in Example 1;

The use method is the same as that of Example 1.

Example 6

In the electrolyte for efficiently regulating the dissolution behavior of magnesium anode, the concentration of sodium chloride is 0.5M, and the concentration of 5-sulfosalicylic acid is 0.1M;

The preparation method is the same as in Example 1;

The use method is the same as that of Example 1.

Example 7

In the electrolyte for efficiently regulating the dissolution behavior of magnesium anode, the concentration of sodium chloride is 0.7M, and the concentration of 5-sulfosalicylic acid is 0.01M;

The preparation method is the same as in Example 1;

The use method is the same as that of Example 1.

Example 8

In the electrolyte for efficiently regulating the dissolution behavior of magnesium anode, the concentration of sodium chloride is 0.7M, and the concentration of 5-sulfosalicylic acid is 0.1M;

The preparation method is the same as in Example 1;

The use method is the same as that of Example 1.

Claims (9)

1. an electrolytic solution for efficiently regulating and controlling magnesium anode dissolving behavior, it is characterized in that being the mixed aqueous solution of sodium chloride and 5-sulfosalicylic acid, wherein the concentration of sodium chloride is 0.5～0.7M, 5-sulfosalicylic acid The concentration of salicylic acid is 0.01-0.1M, and the pH value is 7.0±0.2. 2. the preparation method of the electrolytic solution of the high-efficiency regulation and control of magnesium anode dissolving behavior according to claim 1, is characterized in that carrying out by the following steps: (1) sodium chloride and 5-sulfosalicylic acid are mixed to make mixed material; (2) deionized water is added to the mixture, and then all the materials are stirred until a transparent solution is formed; (3) The pH value of the transparent solution is adjusted with sodium hydroxide or hydrochloric acid to pH value=7.0±0.2, so as to prepare an electrolyte for efficiently regulating the dissolution behavior of magnesium anode. 3. the preparation method of the electrolyte of the highly efficient regulation and control of magnesium anode dissolving behavior according to claim 2, is characterized in that in step (2), when adding deionized water, is to place mixture material in container, deionized water is Pour along the inside of the container. 4. The preparation method of the electrolyte for efficiently regulating and controlling the dissolving behavior of magnesium anode according to claim 2, characterized in that in step (2), the stirring speed is 100～150rpm. 5. the preparation method of the electrolyte of the high-efficiency regulation and control of magnesium anode dissolving behavior according to claim 2, is characterized in that in step (3), monitors with pH-conductivity meter when adjusting pH value. 6. the using method of the electrolyte of the high-efficiency regulation and control of magnesium anode dissolving behavior as claimed in claim 1, is characterized in that: magnesium anode is placed in the electrolyte of high-efficiency regulation and control of magnesium anode dissolving behavior, constitutes a magnesium-air battery; The power supply energizes the magnesium anode. 7. The using method of the electrolyte for efficiently regulating and controlling the dissolving behavior of magnesium anode according to claim 6, wherein the material of the magnesium anode is pure magnesium with a purity of ≥99.5%. 8 . The method for using the electrolyte for efficiently regulating and controlling the dissolution behavior of magnesium anode according to claim 6 , wherein the current density of energization is 2.5-10 mA·cm ⁻² . 9. according to the using method of the electrolytic solution of the high-efficiency regulation and control of magnesium anode dissolving behavior of claim 6, it is characterized in that the cathode is an air cathode.

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