阅读说明：本技术 一种电解液缓蚀剂、铝空气电池、碱性电解液及其制备方法 (Electrolyte corrosion inhibitor, aluminum-air battery, alkaline electrolyte and preparation method thereof ) 是由 胡超权 马川川 许雪冰 邵明远 于 2020-04-02 设计创作，主要内容包括：本发明属于新能源电池技术领域,具体公开了一种电解液缓蚀剂、铝空气电池、碱性电解液及其制备方法,所述电解液缓蚀剂由乙二醇和锡酸钠组成。本发明还将所述的复合缓蚀剂用于制备铝空气电池的碱性电解液。本发明中乙二醇和锡酸钠复合缓蚀剂具有协同作用,能有效抑制铝电极自腐蚀,可使电池的自腐蚀反应大大降低,电极利用效率增高,放电效果也有较大提高,并具有组分构成简单,成本低,安全且符合环保要求等特点。(The invention belongs to the technical field of new energy batteries, and particularly discloses an electrolyte corrosion inhibitor, an aluminum-air battery, an alkaline electrolyte and a preparation method thereof. The invention also uses the composite corrosion inhibitor in the preparation of alkaline electrolyte of aluminum-air battery. The ethylene glycol and sodium stannate composite corrosion inhibitor has a synergistic effect, can effectively inhibit the self-corrosion of an aluminum electrode, can greatly reduce the self-corrosion reaction of a battery, improves the utilization efficiency of the electrode, greatly improves the discharge effect, and has the characteristics of simple component composition, low cost, safety, environmental protection meeting and the like.)

1. The electrolyte corrosion inhibitor is characterized in that raw materials of the electrolyte corrosion inhibitor comprise ethylene glycol and sodium stannate.

2. The electrolyte corrosion inhibitor of claim 1, wherein the sodium stannate comprises anhydrous sodium stannate and/or sodium stannate trihydrate.

3. The electrolyte corrosion inhibitor according to claim 1 or 2, wherein the molar ratio of sodium stannate to ethylene glycol is (1-500): (1-15), preferably (1-100): 1.

4. The electrolyte corrosion inhibitor of claim 3, wherein the molar ratio of sodium stannate to ethylene glycol is (1-50): 1.

5. An alkaline electrolyte comprising a strong base and the electrolyte corrosion inhibitor of any one of claims 1 to 4.

6. The alkaline electrolyte as claimed in claim 5, wherein the concentration of ethylene glycol in the alkaline electrolyte is 0.001 to 0.15 mol/L, preferably 0.01 to 0.15 mol/L, more preferably 0.1 mol/L;

preferably, the concentration of the sodium stannate in the alkaline electrolyte is 0.01-0.5 mol/L, preferably 0.04-0.06 mol/L, and further preferably 0.05 mol/L;

preferably, the concentration of the strong base in the alkaline electrolyte is 1-7 mol/L, preferably 4-6 mol/L.

7. The alkaline electrolyte as claimed in claim 5 or 6, wherein the strong base comprises sodium hydroxide and/or potassium hydroxide.

8. The method for producing an alkaline electrolyte as claimed in any of claims 5 to 7, wherein: mixing a strong alkaline solution with the electrolyte corrosion inhibitor of any one of claims 1-4 in a formula amount to obtain the alkaline electrolyte.

9. The method according to claim 8, wherein the concentration of ethylene glycol in the alkaline electrode solution is 0.001 to 0.15 mol/L, the concentration of sodium stannate is 0.01 to 0.5 mol/L, and the concentration of strong base is 1 to 7 mol/L.

10. An aluminum-air battery, characterized in that it comprises the alkaline electrolyte according to any one of claims 5 to 7.

Technical Field

The invention belongs to the technical field of new energy batteries, and relates to an electrolyte corrosion inhibitor, an aluminum-air battery, an alkaline electrolyte and a preparation method thereof.

Background

Metallic aluminum is the most abundant metal element in the earth's crust, and the recovery of aluminum is relatively simple. The theoretical specific energy of the metal aluminum is 8.2wh/kg, but when the metal aluminum is used as an aluminum electrode, the practical specific energy can only reach 320 wh/kg and 400wh/kg, and even then, the metal aluminum is 6-8 times that of a lead-acid battery and 2-3 times that of a lithium battery.

However, severe self-corrosion of aluminum electrodes in alkaline electrolytes can lead to fuel loss during standby of the cell; in the neutral electrolyte, a layer of compact oxide film is spontaneously formed on the surface of the aluminum, and the activity of the aluminum electrode is slowed down. These problems have hindered the development of aluminum air batteries.

In order to reduce the self-corrosion effect of aluminum electrodes, there are generally two methods. The first method is to alloy the aluminum electrode, the alloying elements are Mg, Mn, Pb, Bi, Cd, Zn, Sn, In, Ga, etc., which can improve the hydrogen evolution potential of the aluminum electrode, slow down the corrosion of the aluminum electrode, destroy the oxide film of the aluminum electrode and increase the activity of the aluminum electrode.

Another method is to add some corrosion inhibitor to the electrolyte to slow down the corrosion reaction of the aluminum electrode. The corrosion inhibitor is divided into organic additives and inorganic additives.

CN 105870545A discloses an electrolyte corrosion inhibitor, an aluminum-air battery electrolyte and a preparation method thereof, wherein the electrolyte corrosion inhibitor mainly comprises an inorganic phase-forming corrosion inhibitor and an organic adsorption type corrosion inhibitor, the inorganic phase-forming corrosion inhibitor is selected from at least one of zinc acetate, manganate or scandium nitrate, and the organic adsorption type corrosion inhibitor is selected from at least one of benzotriazole, natural amino acid and cationic surfactant. However, the electrolyte corrosion inhibitor has high cost and complex components.

Therefore, the electrolyte corrosion inhibitor can effectively inhibit the self-corrosion of the aluminum electrode, reduce the self-corrosion reaction rate of the battery and improve the utilization efficiency of the battery, and has important significance for promoting the development of the aluminum air battery.

Disclosure of Invention

The invention aims to provide an electrolyte corrosion inhibitor, an aluminum-air battery, an alkaline electrolyte and a preparation method thereof. The ethylene glycol and sodium stannate composite corrosion inhibitor has a synergistic effect, can effectively inhibit the self-corrosion of an aluminum electrode, can greatly reduce the self-corrosion reaction of a battery, improves the utilization efficiency of the electrode, greatly improves the discharge effect, and has the characteristics of simple component composition, low cost, safety, environmental protection requirement compliance and the like.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the invention provides an electrolyte corrosion inhibitor, wherein the electrolyte corrosion inhibitor comprises ethylene glycol and sodium stannate as raw materials.

Ethylene glycol ((CH)₂OH)₂) The corrosion inhibitor is transparent liquid at normal temperature, and as an organic corrosion inhibitor, ethylene glycol can stably exist in an alkaline solution. The ethylene glycol contains two hydroxyl polar groups, has good biocompatibility and biodegradability, and the polar groups can be adsorbed on the surface of aluminum, so that the corrosion inhibition effect is achieved.

Sodium stannate is an inorganic corrosion inhibitor, can play a role in inhibiting hydrogen evolution, can reduce polarization of an aluminum electrode, and can negatively shift the potential of the aluminum electrode, because the sodium stannate can generate a metal Sn layer on the surface of the aluminum electrode after being dissolved:

SnO₃ ^2-+3H₂O+4e^-→Sn+6OH^-

however, when sodium stannate is used alone as a corrosion inhibitor, the tin layer deposited on the surface of the aluminum electrode is not uniform, and the formed tin layer has high porosity, so that the tin layer cannot play a good slow release role. The addition of ethylene glycol promotes the deposition of tin on the surface of the aluminum electrode through the synergistic effect of sodium stannate and ethylene glycol; moreover, the addition of the ethylene glycol enhances the geometric coverage effect of the tin layer, inhibits the aggregation and the falling-off of tin, is beneficial to the uniform deposition and the adsorption of the tin, and ensures that the tin layer is uniform and stable.

Therefore, the invention uses the ethylene glycol and the sodium stannate to form the electrolyte corrosion inhibitor, so that a layer of uniform and porous layered structure can be formed on the surface of the aluminum electrode.

Preferably, the sodium stannate comprises anhydrous sodium stannate and/or sodium stannate trihydrate.

Preferably, the molar ratio of sodium stannate to ethylene glycol is (1-500): 1-15, and may be, for example, 1:1, 1:5, 1:10, 1:15, 50:1, 100:1, or 500: 1. The numerical values are not limited to those listed, and other numerical values not listed in the numerical range are also applicable, and are preferably (1-100):1, and more preferably (1-50): 1.

Exemplary preparation methods of the electrolyte corrosion inhibitor of the present invention include, but are not limited to: and mixing ethylene glycol and sodium stannate, stirring and standing to obtain the electrolyte corrosion inhibitor.

The stirring method is a conventional stirring method in the field, and a person skilled in the art can reasonably select the stirring method according to the process requirement.

In a second aspect, the present invention provides an alkaline electrolyte comprising a strong base and the electrolyte corrosion inhibitor of the first aspect.

Preferably, the concentration of ethylene glycol in the alkaline electrolyte is 0.001-0.15 mol/L, such as 0.001 mol/L, 0.005 mol/L0, 0.01 mol/L1, 0.03 mol/L, 0.05 mol/L, 0.08 mol/L, 0.1 mol/L, 0.12 mol/L or 0.15 mol/L, but not limited to the values listed, and other values not listed within the range of values are equally applicable, preferably 0.01-0.15 mol/L, and more preferably 0.1 mol/L.

Preferably, the concentration of sodium stannate in the alkaline electrolyte is 0.01-0.5 mol/L, such as 0.01 mol/L, 0.03 mol/L0, 0.04 mol/L1, 0.05 mol/L2, 0.06 mol/L3, 0.07 mol/L, 0.1 mol/L, 0.2 mol/L, 0.3 mol/L, 0.4 mol/L, or 0.5 mol/L, but not limited to the values listed, and other values not listed in the range of values are also applicable, preferably 0.04-0.06 mol/L, and more preferably 0.05 mol/L.

Preferably, the concentration of the strong base in the alkaline electrolyte is 1-7 mol/L, such as 1 mol/L, 2 mol/L, 3 mol/L, 4 mol/L, 5 mol/L, 6 mol/L or 7 mol/L, but not limited to the recited values, and other values not recited in the numerical range are also applicable.

Preferably, the strong base comprises sodium hydroxide and/or potassium hydroxide.

In a third aspect, the present invention provides a method for producing an alkaline electrolyte as claimed in the second aspect of the present invention: and mixing a strong alkaline solution with the electrolyte corrosion inhibitor of the first aspect according to a formula amount to obtain the alkaline electrolyte.

The preparation method of the third aspect of the invention has the advantages of simple operation, low cost and good application prospect.

The formula amount mixing means that the concentration of ethylene glycol in the prepared alkaline electrolyte is 0.001-0.15 mol/L, the concentration of sodium stannate is 0.01-0.5 mol/L, and the concentration of strong base is 1-7 mol/L.

In a fourth aspect, the present invention provides an aluminum-air battery comprising the alkaline electrolyte as described in the third aspect.

The alkaline electrolyte is applied to the aluminum-air battery, and not only can the hydrogen evolution rate of the aluminum-air battery be controlled, but also the aluminum electrode alloy can have high electrochemical activity, so that the aluminum-air battery has important significance for improving the battery performance and prolonging the discharge life, and is beneficial to large-scale popularization and application of the aluminum-air battery.

Compared with the prior art, the invention has the following beneficial effects:

(1) the electrolyte corrosion inhibitor disclosed by the invention has the advantages that the tin layer with uniform porosity can be formed on the surface of the aluminum electrode by utilizing the synergistic effect of the ethylene glycol and the sodium stannate, the hydrogen evolution self-corrosion rate of the aluminum electrode can be obviously reduced, the open-circuit potential of the aluminum electrode and the working potential under the condition of impressed current can be obviously shifted negatively, the anode efficiency is increased, and the aluminum electrode has good corrosion resistance and higher electrochemical activity so as to meet the requirement of high-current density discharge of an alkaline aluminum-air battery;

(2) the alkaline electrolyte provided by the invention can control the hydrogen evolution rate of the aluminum air battery, can enable the aluminum electrode alloy to have higher electrochemical activity, has important significance for improving the battery performance and prolonging the discharge life, and is beneficial to large-scale popularization and application of the aluminum air battery;

(3) the preparation method of the alkaline electrolyte provided by the invention is simple to operate, low in cost and good in application prospect.

Drawings

FIG. 1 is a scanning electron micrograph of an aluminum anode after static self-etching in an alkaline electrolyte as provided in example 7;

FIG. 2 is a scanning electron micrograph of an aluminum anode after static self-etching in the alkaline electrolyte provided in comparative example 1;

FIG. 3 is a scanning electron micrograph of an aluminum anode after static self-etching in the alkaline electrolyte provided in comparative example 2;

FIG. 4 is a scanning electron micrograph of an aluminum anode after static self-etching in the alkaline electrolyte provided in comparative example 3.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.