CN115395103A - Magnesium alloy conductive oxidation liquid - Google Patents

Abstract

The invention belongs to the technical field of battery electrolyte, and specifically relates to a magnesium alloy conductive oxidation solution, which is composed of an organic solvent, a magnesium salt, a corrosion inhibitor and an antioxidant. It is prepared in parts by weight, wherein 40-80 parts of organic solvent, 5-20 parts of magnesium salt, 2-8 parts of corrosion inhibitor and 5-10 parts of antioxidant. The present invention adopts the electrolytic solution obtained by mixing magnesium bromide and magnesium perchlorate, with the use of antioxidant and corrosion inhibitor, the corrosion inhibition rate of the magnesium alloy block is relatively low, and the discharge voltage of the magnesium alloy block in the electrolyte is relatively high , is an ideal electrolyte, and also uses the mixture of magnesium citrate and ammonia water to increase the thickness of the oxide film on the outer surface of the magnesium alloy block. At the same time, the preparation of the two is relatively simple, and no toxic substances will be produced, which is more friendly to the environment.

Description

A kind of magnesium alloy conductive oxidation solution

technical field

The invention belongs to the technical field of battery electrolytes, and in particular relates to a magnesium alloy conductive oxidation solution.

Background technique

Magnesium alloy is an alloy composed of magnesium and other elements. Its advantages lie in low density, high strength, good heat dissipation and strong electrical conductivity. It also has good corrosion resistance to organic matter and alkali, and the chemical properties of magnesium are lively. , is easily oxidized, and people have developed a magnesium battery based on this point. Compared with lithium batteries, the discharge voltage and charge capacity of magnesium batteries are higher than it, but due to its active chemical properties, it is prone to oxidation The resulting oxide film is relatively loose, which also shows that its corrosion resistance in the electrolyte is poor. Therefore, it is necessary to improve the oxidation resistance of the magnesium alloy in the electrolyte.

Hydroxides and aluminum salts are the most widely used electrolytes for electrolysis of magnesium alloys, where the hydroxide ions in the hydroxides complex the magnesium ions and then attach a layer on the outer surface of the magnesium alloy block. Magnesium hydroxide can easily lead to passivation of the magnesium alloy block, and the use of aluminum salts will easily lead to changes in the structure of the anti-oxidation film, which in turn will lead to a decrease in the corrosion resistance of the oxide film, so that the magnesium alloy block will still occur. Corrosion phenomenon.

Contents of the invention

The purpose of the present invention is to provide a kind of magnesium alloy conductive oxidation solution, which can utilize the mixing of magnesium citrate and ammonia water to increase the thickness of the oxide film on the outer surface of the magnesium alloy block. It is more friendly to the environment.

The technical scheme that the present invention takes is specifically as follows:

A magnesium alloy conductive oxidation solution, which is composed of a mixture of organic solvent, magnesium salt, corrosion inhibitor and antioxidant, and the organic solvent, magnesium salt, corrosion inhibitor and antioxidant are configured in parts by weight, wherein the organic solvent is 40- 80 parts, magnesium salt 5-20 parts, corrosion inhibitor 2-8 parts, antioxidant 5-10 parts.

As a preferred solution of the magnesium alloy conductive oxidation solution in the present invention, wherein: the organic solvent is any one of ether compounds and pyridine compounds.

As a preferred solution of the magnesium alloy conductive oxidation solution of the present invention, wherein: the ether compound is any one of tetrahydrofuran and 1,4-dioxane.

As a preferred solution of the magnesium alloy conductive oxidation solution of the present invention, wherein: the pyridine compound is any one of halogenated pyridine, aminopyridine, chloropyridine, ethylpyridine and fluoropyridine.

As a preferred solution of the magnesium alloy conductive oxidation solution in the present invention, the magnesium salt is at least one of magnesium bromide, magnesium perchlorate, magnesium carbonate and magnesium chloride.

As a preferred solution of the magnesium alloy conductive oxidation solution in the present invention, the magnesium perchlorate is anhydrous magnesium perchlorate.

As a preferred solution of the magnesium alloy conductive oxidation solution in the present invention, the magnesium carbonate is magnesium carbonate trihydrate.

As a preferred solution of the magnesium alloy conductive oxidation solution in the present invention, wherein: the corrosion inhibitor is any one of zinc sulfate, potassium permanganate and sodium fluoride.

As a preferred solution of the magnesium alloy conductive oxidation solution in the present invention, wherein: the antioxidant is at least one of citrate, ammonia water and diethylenetriamine.

As a preferred solution of the magnesium alloy conductive oxidation solution in the present invention, wherein: the citrate is any one of magnesium citrate or sodium citrate.

The technical effect that the present invention obtains is:

The present invention adopts the electrolytic solution obtained by mixing magnesium bromide and magnesium perchlorate, with the use of antioxidant and corrosion inhibitor, the corrosion inhibition rate of the magnesium alloy block is relatively low, and the discharge voltage of the magnesium alloy block in the electrolyte is relatively high , is an ideal electrolyte;

The invention utilizes the mixture of magnesium citrate and ammonia water to increase the thickness of the oxide film on the outer surface of the magnesium alloy block, and meanwhile, the preparation of the two is relatively simple, no toxic substance will be produced, and the method is more friendly to the environment.

Description of drawings

Fig. 1 is the discharge voltage test figure in embodiment 1 to embodiment 3 of the present invention;

Fig. 2 is a discharge voltage test chart in Embodiment 5 and Embodiment 6 of the present invention.

Detailed ways

In order to make the objects and advantages of the present invention clearer, the present invention will be specifically described below in conjunction with examples. It should be understood that the following words are only used to describe one or several specific implementation modes of the present invention, and do not strictly limit the protection scope of the specific claims of the present invention.

A magnesium alloy conductive oxidation solution, which is composed of a mixture of organic solvent, magnesium salt, corrosion inhibitor and antioxidant, characterized in that: the organic solvent, magnesium salt, corrosion inhibitor and antioxidant are configured in parts by weight, wherein, 40-80 parts of organic solvent, 5-20 parts of magnesium salt, 2-8 parts of corrosion inhibitor, 5-10 parts of antioxidant.

Specifically, the organic solvent is any one of ether compounds and pyridine compounds, the ether compounds are any one of tetrahydrofuran and 1,4-dioxane, and the pyridine compounds are halogenated pyridines, aminopyridines, Any one of chloropyridine, ethylpyridine and fluoropyridine, the magnesium salt is at least one of magnesium bromide, magnesium perchlorate, magnesium carbonate and magnesium chloride, magnesium perchlorate is anhydrous magnesium perchlorate, carbonic acid Magnesium is magnesium carbonate trihydrate, the corrosion inhibitor is any one of zinc sulfate, potassium permanganate and sodium fluoride, the antioxidant is at least one of citrate, ammonia and diethylenetriamine, lemon The acid salt is either magnesium citrate or sodium citrate.

Example 1

This embodiment provides a kind of magnesium alloy electroconductive oxidation solution, comprises the material of following parts by weight:

50 parts of tetrahydrofuran, 5 parts of magnesium bromide, 5 parts of sodium fluoride, and 5 parts of magnesium citrate, wherein tetrahydrofuran, magnesium bromide and magnesium citrate are all 5 parts in equal amounts, and sodium fluoride is divided into 5 parts with different concentrations. Parts, which are respectively, 4mol/L, 6mol/L, 8mol/L, 10mol/L and 12mol/L, and they are mixed and configured into a conductive oxidation solution;

Take 5 magnesium alloy ingots with the same surface area and a mass of 50 mg, place them in different conductive oxidizing solutions, soak for 1 hour, then pass a constant current of 3 A for 8 hours, then take out the magnesium alloy ingots, and It is washed with deionized water, dried with hot air (10-20°C) and then weighed. The weighing result is compared with the mass of the magnesium alloy block before it is placed in the conductive oxidizing solution. The comparison result As shown in the table below:

Magnesium alloy block Sodium fluoride (mol/L) Initial mass (mg) Mass after test (mg) 1 4 50 41.28 2 6 50 44.34 3 8 50 46.47 4 10 50 45.68 5 12 50 44.75

Table 1

From the data in Table 1, it can be seen that with the increase of the concentration of sodium fluoride, the mass change of the magnesium alloy plate gradually decreases, and when the concentration reaches 10mol/L, the mass change of the magnesium alloy plate before and after the test is small, that is, It shows that sodium fluoride at this concentration can play a better corrosion inhibition effect, making the magnesium alloy plate have the least effect on self-corrosion, and its corrosion inhibition rate can reach 93.34%.

It should be noted that the concentration of magnesium citrate in this example is 6 mol/L.

Based on the above-mentioned conductive oxidizing solution, the present invention measures its discharge voltage when a constant current is applied, and the specific voltage change schematic diagram is shown in FIG. 1 .

It can be seen that when the concentration of sodium fluoride reaches 10mol/L, the corrosion inhibition rate is not only high, but also the discharge voltage is relatively high.

Example 2

This example is based on the previous example, mainly in that the concentration of antioxidants is different.

Substances comprising the following parts by weight:

50 parts of tetrahydrofuran, 5 parts of magnesium bromide, 5 parts of sodium fluoride, and 5 parts of magnesium citrate, wherein tetrahydrofuran, magnesium bromide and sodium fluoride are all 5 parts in equal amounts, and magnesium citrate is 5 parts of different concentrations. They are respectively 2mol/L, 4mol/L, 6mol/L, 8mol/L and 10mol/L, and they are respectively mixed to form a conductive oxidation solution.

Take 5 magnesium alloy ingots with the same surface area and a mass of 50 mg, place them in different conductive oxidizing solutions, soak for 1 hour, then pass a constant current of 3 A for 8 hours, then take out the magnesium alloy ingots, and It is washed with deionized water, dried with hot air (10-20°C) and then weighed. The weighing result is compared with the mass of the magnesium alloy block before it is placed in the conductive oxidizing solution. The comparison result As shown in the table below:

Magnesium alloy block Magnesium citrate (mol/L) Initial mass (mg) Mass after test (mg) 1 2 50 42.06 2 4 50 44.73 3 6 50 48.23 4 8 50 48.56 5 10 50 48.75

Table 2

From the data in Table 2, it can be seen that as the concentration of magnesium citrate gradually increases, the mass change of the magnesium alloy block before and after the test is also gradually decreasing. After the concentration of magnesium citrate reaches 6mol/L, continue to increase its concentration , the quality change trend of the magnesium alloy plate is not obvious, which means that the concentration of magnesium citrate reaches 6mol/L is the best effect, and the corrosion resistance of the magnesium alloy plate in this state is stronger;

Among them, both citrate ions and fluoride ions can complex magnesium ions, and will form a protective film on the outer surface of the magnesium alloy plate, and both of them are weakly acidic, and they will not react strongly to capture each other. Carrying metal ions, the thickness of the protective film formed can be increased accordingly, which increases the corrosion resistance of the magnesium alloy plate, and the free hydrogen ions in the solvent combine with citrate ions and fluoride ions to form citric acid and hydrofluoric acid respectively. Furthermore, the electrolysis speed of the magnesium alloy block can be increased, so that its electrical conductivity can be increased accordingly, and at the same time, the neutralization of the hydrogen ions by the citrate ions and the fluorine ions can inhibit the hydrogen evolution in the electrolyte.

It should be noted that, in this embodiment, the concentration of sodium fluoride is set to 10 mol/L.

Further, according to the data in Table 2 and Table 1, when the concentration of magnesium citrate is below 6mol/L, even if the concentration of sodium fluoride reaches the optimum, although the quality of the magnesium alloy plate after testing is improved, However, its range of improvement is almost negligible. It can be seen that magnesium citrate below 6mol/L has almost no effect on the corrosion of magnesium alloy plates.

Based on the above-mentioned conductive oxidizing solution, the present invention measures its discharge voltage when a constant current is applied, and the specific voltage change schematic diagram is shown in FIG. 1 .

Example 3

This embodiment is based on the previous embodiment, mainly in that other environments are the same, but the antioxidants are different.

Substances comprising the following parts by weight:

50 parts of tetrahydrofuran, 5 parts of magnesium bromide, 5 parts of sodium fluoride, and 5 parts of ammonia water, wherein tetrahydrofuran, magnesium bromide and sodium fluoride are all 5 parts in equal amounts, and ammonia water is 5 parts of different concentrations, which are respectively, 2mol/L, 4mol/L, 6mol/L, 8mol/L and 10mol/L, and mix them respectively to form a conductive oxidation solution.

Take 5 magnesium alloy ingots with the same surface area and a mass of 50 mg, place them in different conductive oxidizing solutions, soak for 1 hour, then pass a constant current of 3 A for 8 hours, then take out the magnesium alloy ingots, and It is washed with deionized water, dried with hot air (10-20°C) and then weighed. The weighing result is compared with the mass of the magnesium alloy block before it is placed in the conductive oxidizing solution. The comparison result As shown in the table below:

Magnesium alloy block Ammonia (mol/L) Initial mass (mg) Mass after test (mg) 1 2 50 40.12 2 4 50 43.66 3 6 50 45.27 4 8 50 45.33 5 10 50 45.86

table 3

From the data in Table 3, it can be seen that as the concentration of ammonia water gradually increases, the mass change of the magnesium alloy block before and after the test is also gradually decreasing. After the concentration of ammonia water reaches 6mol/L, continue to increase its concentration, and the magnesium alloy plate The quality change trend is not obvious, which means that the best effect is when the concentration of ammonia water reaches 6mol/L, and the corrosion resistance of the magnesium alloy plate in this state is relatively strong.

Specifically, the equation for the reaction between ammonia water and magnesium ions is: Mg ²⁺ +2NH ₃ ·H ₂ O=Mg(OH) ₂ +NH ⁴⁺ , which can form a protective layer of magnesium hydroxide on the outer surface of the magnesium alloy plate. film, so as to protect the magnesium alloy plate from being corroded, based on this, this embodiment also conducts a discharge voltage test on this basis, please refer to Figure 1 for details.

Combining the data in Table 3 and Table 2, it can be seen that the effect of ammonia water as an antioxidant cannot reach the effect of magnesium citrate as an antioxidant, based on this.

As shown in Figure 1, it can be judged that with the increase of the concentration of ammonia water, the discharge voltage is also gradually increasing, but when the concentration of ammonia water exceeds 6mol/L, the discharge voltage drops sharply, which shows that the ammonia water Magnesium hydroxide combined with magnesium ions accumulates on the outer surface of the magnesium alloy, thereby passivating the magnesium alloy, and its electrolysis effect is correspondingly reduced. It can be shown that in this experiment, the concentration of ammonia water is 6mol/L. Works best.

Example 4

This embodiment is based on embodiment 1 and embodiment 2, mainly lies in that other environments are the same, but the type of magnesium salt is different.

Substances comprising the following parts by weight:

30 parts of tetrahydrofuran, 1 part of magnesium perchlorate, 1 part of magnesium carbonate, 1 part of magnesium chloride, 3 parts of sodium fluoride, 3 parts of magnesium citrate, wherein tetrahydrofuran, sodium fluoride and magnesium citrate are all 3 parts in equal amounts, And mix it with magnesium perchlorate, magnesium carbonate and magnesium chloride respectively to form a conductive oxidation solution.

Take three magnesium alloy ingots with the same surface area and a mass of 50 mg and place them in different conductive oxidizing solutions for 1 hour, then pass through a constant current of 3 A for 8 hours, then take out the magnesium alloy ingots, and It is washed with deionized water, dried with hot air (10-20°C) and then weighed. The weighing result is compared with the mass of the magnesium alloy block before it is placed in the conductive oxidizing solution. The comparison result As shown in the table below:

Magnesium alloy block magnesium salt Initial mass (mg) Mass after test (mg) 1 Magnesium perchlorate 50 44.85 2 magnesium carbonate 50 43.53 3 magnesium chloride 50 44.26

Table 4

With reference to embodiment 1-2, can obtain by table 4 data, magnesium perchlorate, magnesium carbonate and magnesium chloride are in the electrolytic solution that tetrahydrofuran, sodium fluoride and magnesium citrate mix, and its quality after the test is all less than that with magnesium bromide effect as an electrolyte.

Example 5

This embodiment is based on the previous embodiment, and mainly lies in that other environments are the same, and the mixed types of magnesium salts are different.

Substances comprising the following parts by weight:

30 parts of tetrahydrofuran, 3 parts of magnesium bromide, 1 part of magnesium perchlorate, 1 part of magnesium carbonate, 1 part of magnesium chloride, 3 parts of sodium fluoride, 3 parts of magnesium citrate, of which tetrahydrofuran, magnesium bromide, sodium fluoride and lemon Magnesium acid is equal to 3 parts, and they are respectively mixed and configured into a conductive oxidizing solution.

Take three magnesium alloy ingots with the same surface area and a mass of 50 mg and place them in different conductive oxidizing solutions for 1 hour, then pass through a constant current of 3 A for 8 hours, then take out the magnesium alloy ingots, and It is washed with deionized water, dried with hot air (10-20°C) and then weighed. The weighing result is compared with the mass of the magnesium alloy block before it is placed in the conductive oxidizing solution. The comparison result As shown in the table below:

Magnesium alloy block magnesium salt Initial mass (mg) Mass after test (mg) 1 Magnesium perchlorate 50 46.64 2 magnesium carbonate 50 44.63 3 magnesium chloride 50 43.79

Table 5.1

As can be seen from the data in Table 5, magnesium bromide was mixed with magnesium perchlorate, magnesium carbonate and magnesium chloride respectively, and then tested again. Compared with the test results of Example 4, the quality of the magnesium alloy after the test was significantly improved. , especially the mass increase of magnesium perchlorate and magnesium carbonate is particularly obvious, and the mass increase of magnesium perchlorate is the largest,

Based on above-mentioned test result, change the concentration of magnesium perchlorate and mix and test respectively with magnesium bromide, comprise the material of following parts by weight:

50 parts of tetrahydrofuran, 5 parts of magnesium bromide, 5 parts of magnesium perchlorate, 5 parts of sodium fluoride, and 5 parts of magnesium citrate, in which 5 parts of tetrahydrofuran, magnesium bromide, sodium fluoride and magnesium citrate are equal , magnesium perchlorate is divided into 5 different concentrations, specifically: 0.5mol/L, 1mol/L, 1.5mol/L, 2mol/L and 2.5mol/L, and they are mixed and configured into a conductive oxidation solution ;

Take 5 magnesium alloy ingots with the same surface area and a mass of 50 mg, place them in different conductive oxidizing solutions, soak for 1 hour, then pass a constant current of 3 A for 8 hours, then take out the magnesium alloy ingots, and It is washed with deionized water, dried with hot air (10-20°C) and then weighed. The weighing result is compared with the mass of the magnesium alloy block before it is placed in the conductive oxidizing solution. The comparison result As shown in the table below:

Magnesium alloy block Magnesium perchlorate (mol/L) Initial mass (mg) Mass after test (mg) 1 0.5 50 45.91 2 1 50 47.75 3 1.5 50 45.65 4 2 50 43.28 5 2.5 50 41.59

Table 5.2

From the data in Table 5.2, it can be seen that when the amount of magnesium perchlorate added reaches 1mol/L, the mass change of the magnesium alloy block before and after the test is the smallest, and its corrosion inhibition rate reaches 95.50%. , the corrosion rate of the magnesium alloy block also increased correspondingly, which was caused by the corrosion effect of too much perchlorate ion on the magnesium alloy block in the mixed solution.

Further, compared with the test data obtained in the aforementioned examples 1-4, the mixed use of magnesium bromide and magnesium perchlorate can make the corrosion rate of the magnesium alloy block reach the lowest.

Based on this, this embodiment also carried out a discharge voltage test on it, and the specific data are shown in Figure 2. It can be found that the discharge voltage of the magnesium alloy block is relatively stable in the electrolyte solution mixed with magnesium bromide and magnesium perchlorate.

Example 6

This embodiment is based on the previous embodiment, mainly in that other environments are the same, and different types of antioxidants are mixed.

Substances comprising the following parts by weight:

50 parts of tetrahydrofuran, 5 parts of magnesium bromide, 5 parts of magnesium perchlorate, 5 parts of sodium fluoride, 5 parts of magnesium citrate, 5 parts of ammonia water, of which tetrahydrofuran, magnesium bromide, magnesium perchlorate, sodium fluoride and lemon Magnesium acid is 5 parts of the same amount, ammonia water is 5 parts of different concentrations, specifically: 0.5mol/L, 1mol/L, 1.5mol/L, 2mol/L and 2.5mol/L, and they are mixed and configured respectively into a conductive oxidizing solution.

Take 5 magnesium alloy ingots with the same surface area and a mass of 50 mg, place them in different conductive oxidizing solutions, soak for 1 hour, then pass a constant current of 3 A for 8 hours, then take out the magnesium alloy ingots, and It is washed with deionized water, dried with hot air (10-20°C) and then weighed. The weighing result is compared with the mass of the magnesium alloy block before it is placed in the conductive oxidizing solution. The comparison result As shown in the table below:

Magnesium alloy block Ammonia (mol/L) Initial mass (mg) Mass after test (mg) 1 0.5 50 46.22 2 1 50 47.83 3 1.5 50 48.36 4 2 50 43.03 5 2.5 50 41.15

Table 6

It can be obtained from the data in Table 6 that when the concentration of ammonia water reaches 1.5mol/L, the mass change of the magnesium alloy block before and after the test is the smallest, and combined with the data in Table 5.2 in Example 5, it can be obtained that when the concentration of ammonia water is higher than or lower than 1.5mol /L, its effect on magnesium alloy block is almost negligible.

Based on this, a discharge voltage test was also carried out in this embodiment, and the specific data are shown in FIG. 2 .

Based on the test results of Examples 1-6, wherein, when magnesium salt and antioxidant are mixed with a single substance, although it can alleviate the corrosion rate of magnesium alloy block, the effect is not particularly obvious, and multiple magnesium salts or The mixture of antioxidants reduces the corrosion rate of magnesium alloy blocks accordingly, and in this process, neither ammonia nor citric acid will produce toxic substances, and its preparation is simple and environmentally friendly. It is a preferred antioxidant and is suitable as a magnesium alloy. Additive for alloy conductive oxidation solution.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications should also be It is regarded as the protection scope of the present invention. The structures, devices and operation methods not specifically described and explained in the present invention, unless otherwise specified and limited, shall be implemented according to conventional means in the art.

Claims (10)

1. a magnesium alloy conductive oxidizing solution, mixed by organic solvent, magnesium salt, corrosion inhibitor and antioxidant, is characterized in that: described organic solvent, magnesium salt, corrosion inhibitor and antioxidant are configured in parts by weight, Among them, 40-80 parts of organic solvent, 5-20 parts of magnesium salt, 2-8 parts of corrosion inhibitor, and 5-10 parts of antioxidant. 2. A magnesium alloy conductive oxidation solution according to claim 1, characterized in that: the organic solvent is any one of ether compounds and pyridine compounds. 3. A magnesium alloy conductive oxidation solution according to claim 2, characterized in that: the ether compound is any one of tetrahydrofuran and 1,4-dioxane. 4. A magnesium alloy conductive oxidation solution according to claim 2, characterized in that: said pyridine compound is any one of halogenated pyridine, aminopyridine, chloropyridine, ethylpyridine and fluoropyridine. 5. A magnesium alloy conductive oxidation solution according to claim 1, characterized in that: said magnesium salt is at least one of magnesium bromide, magnesium perchlorate, magnesium carbonate and magnesium chloride. 6. A magnesium alloy conductive oxidation solution according to claim 5, characterized in that: the magnesium perchlorate is anhydrous magnesium perchlorate. 7. A magnesium alloy conductive oxidation solution according to claim 5, characterized in that: the magnesium carbonate is magnesium carbonate trihydrate. 8. A magnesium alloy conductive oxidation solution according to claim 1, characterized in that: said corrosion inhibitor is any one of zinc sulfate, potassium permanganate and sodium fluoride. 9. A magnesium alloy conductive oxidation solution according to claim 1, characterized in that: said antioxidant is at least one of citrate, ammonia water and diethylenetriamine. 10. A magnesium alloy conductive oxidation solution according to claim 9, characterized in that: the citrate is any one of magnesium citrate or sodium citrate.

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