阅读说明：本技术 一种碱性电解液复合缓蚀剂和铝空气电池 (Alkaline electrolyte composite corrosion inhibitor and aluminum-air battery ) 是由 杨丽霞 吴云涛 陈烁 肖远强 陈森 王君霞 于 2020-04-13 设计创作，主要内容包括：本发明涉及铝空气电池领域,公开了一种适用于铝空气电池碱性电解液的复合缓蚀剂。该碱性电解液复合缓蚀剂主要由无机成相型缓蚀剂硫酸锌和有机吸附型缓蚀剂海藻酸钠组成。硫酸锌为阴极型缓蚀剂,通过覆盖铝电极表面的阴极析氢活性位点抑制铝电极的自腐蚀行为,不影响铝阳极放电反应的电化学活性；海藻酸钠吸附在锌保护膜上增强了其稳定性。通过向碱性电解液中添加复合缓蚀剂,能有效抑制铝电极的腐蚀从而减缓铝空气电池的自放电现象,同时明显提高铝空气电池的实际放电性能,是一种工艺简单、安全环保、综合性能良好的铝空气电池碱性电解液缓蚀剂。(The invention relates to the field of aluminum-air batteries, and discloses a composite corrosion inhibitor suitable for an alkaline electrolyte of an aluminum-air battery. The alkaline electrolyte composite corrosion inhibitor mainly comprises inorganic phase-forming corrosion inhibitor zinc sulfate and organic adsorption corrosion inhibitor sodium alginate. Zinc sulfate is a cathode corrosion inhibitor, inhibits the self-corrosion behavior of the aluminum electrode by covering the cathode hydrogen evolution active site on the surface of the aluminum electrode, and does not influence the electrochemical activity of the aluminum anode discharge reaction; sodium alginate is adsorbed on the zinc protective film to enhance the stability of the zinc protective film. The composite corrosion inhibitor is added into the alkaline electrolyte, so that the corrosion of an aluminum electrode can be effectively inhibited, the self-discharge phenomenon of the aluminum-air battery is slowed down, the actual discharge performance of the aluminum-air battery is obviously improved, and the aluminum-air battery alkaline electrolyte corrosion inhibitor is simple in process, safe, environment-friendly and good in comprehensive performance.)

1. The aluminum-air battery alkaline electrolyte composite corrosion inhibitor is characterized by comprising inorganic phase-forming corrosion inhibitor zinc sulfate and organic adsorption corrosion inhibitor sodium alginate.

2. The aluminum air cell alkaline electrolyte of claim 1, wherein the strong base is sodium hydroxide.

3. The aluminum-air cell alkaline electrolyte of claim 2, wherein the strong base concentration is 4 mol/L.

4. The aluminum-air battery alkaline electrolyte composite corrosion inhibitor of claim 1, wherein the concentration of the inorganic corrosion inhibitor zinc sulfate ranges from 8 mmol/L to 10 mmol/L, and the organic adsorption corrosion inhibitor is sodium alginate 0.1-2 g/L.

5. An aluminum-air battery, characterized in that the electrolyte comprises the alkaline electrolyte according to any one of claims 1 to 4.

Technical Field

The invention relates to the field of aluminum-air batteries, in particular to an alkaline electrolyte corrosion inhibitor for an aluminum-air battery.

Background

With the continuous progress of society and the rapid development of economy, the demand of human beings on energy is increasing, and a new energy with high efficiency, energy conservation and no pollution is a main direction for the development of the energy field. The metal air battery as a novel fuel battery has the advantages of large specific energy, light weight, small internal resistance, no toxicity, long storage life, relatively low price and the like, and has obvious application advantages in the field of new energy. The aluminum-air battery not only has the series advantages of the fuel battery, but also can prepare high-purity aluminum after the discharge product of the battery is calcined and electrolyzed, and can be used as the cathode material of the battery for regeneration and recycling, thereby being a new energy technology with wide application prospect.

Compared with a neutral electrolyte aluminum air battery, the electrode potential of the aluminum negative electrode in an alkaline electrolyte is relatively negative (-1.66V vs. Hg/HgO), and the discharge product of the aluminum negative electrode is Al (OH)₃The aluminum air battery can be further dissolved in an alkaline solution to generate soluble aluminate, and the influence on the battery efficiency is small, so that the discharge performance of the aluminum air battery in an alkaline electrolyte is higher. However, the aluminum negative electrode can generate serious hydrogen evolution corrosion in alkaline electrolyte to cause the reduction of the utilization rate of the anode, the generated excessive hydrogen also has certain potential safety hazard, and the self-corrosion phenomenon of the aluminum negative electrode material in the alkaline solution seriously influences the service life and the battery safety.

①, adding other alloy elements such as gallium, indium, tin and the like into high-purity aluminum, changing the composition structure of the aluminum cathode to improve the corrosion resistance of the cathode material and the overall efficiency of the battery, ②, adding an additive with a corrosion inhibition effect into alkaline electrolyte to slow down the self-corrosion of the cathode material on the premise of not reducing the discharge performance of the aluminum air battery, and the method ② corrosion inhibitor has the advantages of low cost, simplicity, convenience and the like due to the high alloying cost of the aluminum in the method ①, so that the method is concerned by researchers.

The aluminum-air battery alkaline electrolyte corrosion inhibitor comprises an inorganic corrosion inhibitor, an organic corrosion inhibitor and a composite corrosion inhibitor. Although the single inorganic corrosion inhibitor and the single organic corrosion inhibitor can reduce the corrosion rate of the aluminum electrode to a certain extent, the single inorganic corrosion inhibitor and the single organic corrosion inhibitor usually sacrifice the activity of the aluminum anode. Therefore, the current research on the corrosion inhibitor of the alkaline electrolyte of the aluminum air battery mostly focuses on the inorganic-organic composite corrosion inhibitor with complex components, and the precipitation film and the adsorption film are formed on the metal surface through inorganic-organic composite so as to reduce the self-corrosion rate of the aluminum electrode and reduce the influence on the activity of the aluminum anode. However, the inorganic component of the aluminum-air battery composite corrosion inhibitor has been reported to be ZnO (J.Power sources, 2015,285:100-108) or Na₂SnO₃(electrochim. acta, 2017,248:478-485) mainly, and most of the researches are focused on the corrosion inhibition effect, and the concern about the influence of the corrosion inhibitor on the actual discharge performance of the battery is less. ZnO is a mixed corrosion inhibitor (J.Power sources, 2016,335:1-11), and simultaneously inhibits the anode reaction and the cathode reaction on the surface of the aluminum electrode, so that ZnO can reduce the self-corrosion rate of the aluminum electrode, but also sacrifices the electrochemical activity of the aluminum anode, and further influences the actual discharge performance of the aluminum-air battery; na (Na)₂SnO₃May cause the formation of metal dendrites, short-circuiting or destruction of the battery, and has poor safety, and Na₂SnO₃The Sn protective film generated on the aluminum surface is not uniform (chem.eng.j.,2020,383: 123162).

The invention discloses an electrolyte corrosion inhibitor, an aluminum-air battery electrolyte and a preparation method thereof, wherein the electrolyte comprises strong base and a corrosion inhibitor, the electrolyte corrosion inhibitor comprises a main corrosion inhibitor L-cysteine and an auxiliary corrosion inhibitor zinc oxide, the main corrosion inhibitor L-cysteine is an adsorption type corrosion inhibitor, and is adsorbed on the metal surface to form a uniform and compact hydrophobic layer so as to effectively prevent the contact of an aluminum electrode and water molecules, the auxiliary corrosion inhibitor zinc oxide is a mixed corrosion inhibitor and simultaneously inhibits the anode reaction and the cathode reaction of the aluminum surface, the compound corrosion inhibitor effectively slows down the self-corrosion behavior of the aluminum electrode, however, the compact film layer formed on the metal surface by the main corrosion inhibitor L-cysteine in the patent undoubtedly shields a large number of active sites on the aluminum anode surface, the active sites provided by the defects formed by molecular winding are very limited, the mixed corrosion inhibitor ZnO can further reduce the electrochemical activity of the aluminum anode, and the invention does not concern the actual discharge performance of the aluminum-air battery in the alkaline electrolyte containing the corrosion inhibitor.

The improvement of the corrosion inhibition performance of the alkaline aluminum air battery reported in the patent or the literature is mostly at the expense of the activity of the anode, so that the search for the additive with the obvious improvement of the corrosion inhibition performance and the discharge performance is the bottleneck in the development of the alkaline aluminum air battery.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides the composite corrosion inhibitor for the alkaline electrolyte of the aluminum-air battery, which has simple operation process and composition, low cost, safety and environmental protection, takes the inorganic corrosion inhibitor as the main material and the organic corrosion inhibitor as the auxiliary material, can effectively inhibit the self-corrosion behavior of an aluminum electrode and simultaneously obviously improve the discharge performance of the aluminum-air battery, and the specific implementation mode is as follows:

an alkaline electrolyte composite corrosion inhibitor for an aluminum-air battery comprises an inorganic phase-forming corrosion inhibitor and an organic adsorption corrosion inhibitor, wherein the inorganic phase-forming corrosion inhibitor adopts zinc sulfate, and the organic adsorption corrosion inhibitor selects sodium alginate.

The zinc sulfate is used as a main corrosion inhibitor, is a cathode type corrosion inhibitor, and is used as an alkaline electrolyte additive to generate a protective film on the surface of an aluminum electrode to cover a cathode hydrogen evolution active site, so that the electrochemical activity of the aluminum anode discharge reaction is not influenced while the self-corrosion rate of the aluminum electrode is reduced; in addition to this, the present invention is,promotes the cation selective diffusion layer Al (OH) SO on the surface of the aluminum electrode₄To some extent, hinder Al formation³⁺Diffusion into the solution further reduces the self-corrosion rate of the aluminum electrode in alkaline solution.

The sodium alginate is used as an auxiliary corrosion inhibitor, and is biodegradable, nontoxic and good in film formingThe sexual chain-shaped macromolecular compound is used as a byproduct after iodine and mannitol are extracted from brown algae kelp or gulfweed, and has low price and low use cost. The molecular formula of the sodium alginate is (C)₆H₇NaO₆) And x contains a large amount of carboxylate groups (-COONa), hydroxyl (OH) and heteroatom oxygen, can interact with the zinc film on the surface of the aluminum electrode, and is adsorbed on the surface of the loose and porous zinc film to form an organic/inorganic composite protective film layer with higher stability, so that the self-corrosion behavior of the aluminum anode is inhibited.

Preferably, the amount of zinc sulfate is 8-10 mmol/L.

Preferably, the amount of the sodium alginate is 0.1-2 g/L.

Preferably, the alkaline electrolyte of the aluminum-air battery is sodium hydroxide.

Preferably, the concentration of the alkaline electrolyte of the aluminum-air battery is 4 mol/L.

The preparation method of the aluminum-air battery comprises the following steps: adding the inorganic corrosion inhibitor zinc sulfate into the strong alkali solution to obtain an intermediate solution, and adding the organic corrosion inhibitor sodium alginate into the intermediate solution.

The mechanism is as follows:

the invention innovatively provides a cathode type corrosion inhibitor ZnSO₄ZnSO as a principal corrosion inhibitor for alkaline electrolytes of aluminum-air batteries₄① is different from the corrosion inhibition mechanism in neutral and acid electrolytes, and ZnSO in alkaline electrolytes is different from the corrosion inhibition mechanism in neutral and acid electrolytes₄The addition of (2) promotes the surface of the aluminum electrode to generate a protective film, the chemical reaction is shown as a formula (1) and a formula (2), and Zn²⁺The zinc is unstable in alkaline solution and mainly covers cathode hydrogen evolution active sites on the surface of aluminum in the form of loose and porous oxides and hydroxides, so that the self-corrosion rate of the aluminum electrode is reduced, but the aluminum anode is not influencedElectrochemical activity of discharge reaction ②Promotes the cation selective diffusion layer Al (OH) SO on the surface of the aluminum electrode₄To some extent, hinder Al formation³⁺Diffusion into solution further reduces the self-corrosion rate of aluminum electrodes in alkaline solution ③ ZnSO₄The zinc protective film formed on the surface of the aluminum electrode has a loose structure and is easy to fall off, and sodium alginate molecules have a large amount of polar groups-OH and-COO^-And heteroatom O rich in lone pair electrons, can interact with the zinc film on the surface of the aluminum electrode, is adsorbed on the surface of the loose porous zinc film to form an organic/inorganic composite protective film layer with higher stability, thereby effectively inhibiting the self-corrosion behavior of the aluminum electrode ④ ZnSO₄The composite use of the composite film and SA mainly inhibits the cathodic hydrogen evolution reaction on the surface of the aluminum electrode, has small influence on the dissolution process of the aluminum anode, and the composite film can reduce the accumulation of discharge products on the surface of the aluminum electrode, thereby being beneficial to the improvement of the actual discharge performance of the aluminum-air battery.

The invention has the beneficial effects that:

the alkaline electrolyte composite corrosion inhibitor for the aluminum air battery has the advantages of simple composition, low cost, easiness in operation, safety and environmental friendliness, inhibits the self-corrosion behavior of an aluminum electrode, does not reduce the electrochemical reaction activity of the aluminum electrode, and can obviously improve the actual discharge performance of the aluminum air battery. In addition, the selected inorganic-organic composite corrosion inhibitor does not influence the conductivity of the electrolyte.

Compared with the prior art, the method has the following novelty and technical advantages:

we explore and provide a cathode type corrosion inhibitor ZnSO₄Intended to be effectiveThe self-corrosion behavior of the aluminum cathode material in the alkaline electrolyte is relieved, and the actual discharge performance of the battery is improved. To further improve ZnSO₄The inhibition efficiency of the self-corrosion behavior of the aluminum electrode is that the environment-friendly organic adsorption type corrosion inhibitor sodium alginate and ZnSO are used₄The composite protective film can further inhibit the self-corrosion behavior of the aluminum electrode and improve the actual discharge performance of the aluminum-air battery.

Drawings

FIG. 1 is a graph of open circuit potential versus time monitoring for aluminum electrodes in the electrolytes of examples and comparative examples.

FIG. 2 is a plot of potentiodynamic polarization of aluminum electrodes in the electrolytes of examples and comparative examples.

FIG. 3 is a scanning electron microscope image of an aluminum electrode sample immersed in an electrolyte for 1 hour; (a) comparative example 1, (b) comparative example 2, (c) comparative example 3, (d) example 4.

FIG. 4 is a constant current discharge curve (discharge current density of 30mA cm) of an aluminum-air battery in examples and comparative examples^-2)。

FIG. 5 shows ZnSO in alkaline electrolyte₄The corrosion inhibition mechanism of the/SA composite corrosion inhibitor on the aluminum electrode is shown schematically.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The composite corrosion inhibitor for the alkaline electrolyte of the aluminum-air battery comprises an inorganic phase-forming corrosion inhibitor and an organic adsorption corrosion inhibitor, wherein the inorganic phase-forming corrosion inhibitor adopts a cathode corrosion inhibitor zinc sulfate, and the organic adsorption corrosion inhibitor adopts sodium alginate.

Preferably, the amount of zinc sulfate is 8-10 mmol/L, and the amount of sodium alginate is 0.1-2 g/L.

Preferably, the alkaline electrolyte of the aluminum-air battery is sodium hydroxide.

Preferably, the concentration of the alkaline electrolyte of the aluminum-air battery is 4 mol/L.

The preparation method of the aluminum-air battery is characterized by comprising the following steps: adding the inorganic corrosion inhibitor zinc sulfate into the strong alkali solution to obtain an intermediate solution, and adding the organic corrosion inhibitor sodium alginate into the intermediate solution.