Chelating agent modified organic carboxylate electrolyte and application thereof in magnesium air battery

Abstract

The invention discloses a chelating agent modified organic carboxylate electrolyte and application thereof in a magnesium air battery, and belongs to the field of magnesium air battery electrolytes. Comprising deionized water, carboxylate electrolyte and an organic metal ion chelating agent, the chelating agent is selected from at least one of organic metal ion chelating agents such as ethylene diamine tetraacetic acid, diethylenetriamine pentaacetic acid, ethylene glycol diethyl ether diamine tetraacetic acid, 1, 2-cyclohexanediamine tetraacetic acid or nitrilotriacetic acid. The core of the invention lies in that the chelating effect of the chelating agent and metal ions such as Mg < 2 + > is utilized to effectively inhibit the formation of a passivation film on the surface of the magnesium anode and promote the uniform dissolution of the anode. The composite electrolyte can remarkably improve the discharge voltage, the anode utilization rate and the energy density of the battery at the same time. Based on the excellent electrochemical performance, the organic carboxylate electrolyte containing the organic metal ion chelating agent shows good application potential in the field of magnesium air batteries.

Description

Technical Field

[0001] This invention relates to the field of magnesium-air battery technology, and more specifically to the application of an organic carboxylate-based electrolyte containing an organometallic ion chelating agent in magnesium-air batteries. Background Technology

[0002] The energy crisis and environmental issues have spurred the research and development of new energy storage devices. Magnesium-air batteries, with their advantages of low cost, high specific energy, and environmental friendliness, have broad application prospects in portable power supplies, marine equipment, and other fields. However, their development is limited by problems such as severe self-corrosion of magnesium anodes, low discharge voltage caused by the accumulation of discharge products (such as Mg(OH)2), and poor anode efficiency.

[0003] Electrolytes are crucial for improving battery performance. In traditional chlorine-containing electrolytes, Cl... - This can easily lead to localized corrosion of magnesium anodic electrodes. Studies have shown that using a chloride-free electrolyte such as CH3COONa can inhibit self-corrosion. Water-soluble organic carboxylate salts such as sodium formate (HCOONa), sodium acetate (CH3COONa), sodium propionate (CH3CH2COONa), potassium formate (HCOOK), and potassium acetate (CH3COOK) ionize into carboxylate anions and sodium / potassium ions after dissolving in water, providing a stable anionic environment. These organic carboxylate ions have a larger radius and weaker corrosiveness compared to Cl. - It is more difficult for the passivation film on the magnesium anode surface to penetrate, which helps to inhibit localized corrosion. However, it leads to an increase in activation overpotential and a decrease in discharge voltage. Therefore, finding a functional additive to regulate electrolyte composition and improve the performance of air batteries has become an urgent need. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide an electrolyte that can simultaneously improve the discharge voltage, anode utilization rate and energy density of magnesium-air batteries.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: an organic carboxylate-based electrolyte containing an organometallic ion chelating agent, comprising deionized water, a carboxylate electrolyte, and an organometallic ion chelating agent.

[0006] Furthermore, in the electrolyte:

[0007] The organometallic ion chelating agent is an organic aminocarboxylic acid chelating agent, selected from at least one of ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), ethylene glycol diethyl ether diaminetetraacetic acid (EGTA), and 1,2-cyclohexanediaminetetraacetic acid (CDTA).

[0008] The molar concentration of the organometallic ion chelating agent in the electrolyte is 0.01–0.1 mol / L;

[0009] The carboxylate electrolyte is selected from at least one of sodium formate, sodium acetate, sodium acetate trihydrate, potassium formate, potassium acetate, and potassium acetate trihydrate.

[0010] The molar concentration of the carboxylate electrolyte in the electrolyte is 0.5–1.5 mol / L;

[0011] The pH of the electrolyte was adjusted to 7.0 ± 0.2 using NaOH aqueous solution.

[0012] This invention provides the application of the above-mentioned electrolyte in magnesium-air batteries.

[0013] A magnesium-air battery includes a magnesium anode, an air cathode, and the electrolyte of the present invention.

[0014] The anode material is a Mg-1.5In-0.5Zn-0.2Ca (wt.%) alloy, and the cathode material comprises a multilayer structure consisting of a C / MnO2 catalyst layer, a nickel foam mesh current collector, and a carbon cloth gas diffusion layer.

[0015] Magnesium-air batteries operate at current densities of 1–10 mA / cm². 2 .

[0016] This invention significantly improves the performance of magnesium battery anodes by comprehensively utilizing the synergistic effect of carboxylate electrolytes and organic aminocarboxyl chelating agents:

[0017] Improving discharge voltage: Organic amino carboxyl chelating agents effectively inhibit the formation of passivation films and promote uniform corrosion of magnesium anodes, thereby increasing the discharge voltage. For example, adding 0.06 mol / L EDTA or 0.04 mol / L DTPA to a 1 mol / L CH3COONa basic electrolyte can improve the discharge voltage at 1 mA / cm². 2 At current density, the anodic discharge voltage is as high as 1.96V, which is about 200mV higher than that of the basic electrolyte (about 1.77V).

[0018] Improving anode utilization: Organic amino carboxyl chelating agents complex Mg 2+ This reduces passivation film buildup, promotes uniform anode dissolution, and improves anode utilization. For example, adding 0.02 mol / L DTPA to a 1 mol / L CH3COONa basic electrolyte at 2.5 mA / cm²... 2 At the specified current density, the anode utilization rate reached 74.5% ± 1.78%. Under the same conditions, the anode utilization rate in the base electrolyte was 50.31% ± 1.21%.

[0019] Enhancing specific capacity: Organic amino carboxyl chelating agents promote efficient dissolution of magnesium anodes, increasing the amount of charge released per unit mass of material. For example, adding 0.02 mol / L DTPA to a 1 mol / L CH3COONa basic electrolyte results in a specific capacity of 2.5 mA / cm². 2 At current density, the specific capacity reaches 1618.14 mAh·g. -1 ±7.41mAh·g -1 Under the same conditions, the specific capacity of the basic electrolyte is only 1093.71 mAh·g. -1 ±1.38mAh·g -1 .

[0020] Increased energy density: The synergistic improvement in discharge voltage and specific capacity enhances energy output capability and increases energy density. For example, adding 0.03 mol / L EDTA or 0.02 mol / L DTPA to a 1 mol / L CH3COONa basic electrolyte results in an energy density of 2.5 mA / cm². 2 At current density, the energy density reaches as high as 2594.95 mWh·g. -1 and 2698.21 mWh·g -1 Under the same conditions, the energy density in the basic electrolyte is only 1934.22 mWh·g. -1 ±1.08 mWh·g -1 .

[0021] The innovative mechanism of this invention lies in the fact that organic amino-carboxyl chelating agents contain multiple coordinating groups (such as amino and carboxyl groups) in their molecules, possessing multidentate coordination ability, and can interact with Mg through nitrogen and oxygen atoms. 2+ The formation of stable cyclic chelates by metal ions effectively inhibits the formation of passivation film and promotes uniform corrosion of magnesium anodes. The weakly alkaline environment provided by carboxylate electrolytes enhances the chelating ability of organic amino carboxylates. The synergistic effect of the two improves the discharge performance of magnesium anodes, such as discharge voltage, anode utilization efficiency, and energy density.

[0022] The electrolyte of this invention has a simple composition and advantages such as being non-toxic, environmentally friendly, and low-cost, especially at 2.5 mA / cm². 2 It exhibits excellent performance at current density, meeting the high-efficiency discharge requirements of magnesium-air batteries, and has significant application value.

[0023] The present invention will be further described below with reference to the accompanying drawings and specific implementation methods. Attached Figure Description

[0024] Figure 1 The discharge curves of Example 1 at different current densities are shown.

[0025] Figure 2The discharge voltage and anode utilization rate under different current densities are for Example 1.

[0026] Figure 3 The specific capacity and energy density of Example 1 at different current densities are shown.

[0027] Figure 4 The discharge curves for Example 2 are shown at different current densities.

[0028] Figure 5 The discharge voltage and anode utilization rate under different current densities are shown in Example 2.

[0029] Figure 6 The specific capacity and energy density of Example 2 are shown at different current densities.

[0030] Figure 7 The discharge curves for Example 3 are shown at different current densities.

[0031] Figure 8 The discharge voltage and anode utilization rate under different current densities are shown in Example 3.

[0032] Figure 9 The specific capacity and energy density of Example 3 are shown at different current densities.

[0033] Figure 10 The discharge curves for Example 4 are shown at different current densities.

[0034] Figure 11 The discharge voltage and anode utilization rate under different current densities are shown in Example 4.

[0035] Figure 12 The specific capacity and energy density of Example 4 are shown at different current densities.

[0036] Figure 13 The discharge curves of Comparative Example 1 are shown at different current densities.

[0037] Figure 14 The discharge voltage and anode utilization rate of Comparative Example 1 are shown at different current densities.

[0038] Figure 15 The specific capacity and energy density of Comparative Example 1 are shown at different current densities. Detailed Implementation

[0039] The present invention will be further described below with reference to specific embodiments. It should be noted that these embodiments are only used to illustrate the specific implementation methods of the present invention and do not limit the scope of protection of the present invention.

[0040] This invention evaluates the performance of magnesium-air battery electrolytes containing additives. A LAND battery testing system (model CT2001 A) was used to conduct constant current discharge tests at a constant current density, recording the discharge voltage curves and calculating key parameters such as anode utilization, specific capacity, and energy density. A scanning electron microscope (model GeminiSEM 300) was used to observe the surface morphology of the magnesium alloy working electrode after discharge, analyzing the morphology and deposition of corrosion products, and assessing the influence of the electrolyte on electrode corrosion behavior.

[0041] The preparation method of the magnesium alloy working electrode is as follows: The magnesium alloy to be tested is cut into a sample block with a size of 10mm×10mm×3mm; the 10mm×10mm surface is selected as the working surface, and it is polished step by step with 240#, 800#, 1200# and 2000# sandpaper until the surface is flat and smooth; the polished sample is ultrasonically cleaned with anhydrous ethanol to remove surface residues, and then placed in the air to air dry naturally; the treated magnesium alloy anode is embedded and encapsulated with acrylic resin powder, exposing only the pre-polished working surface.

[0042] Example 1: Electrolyte containing 0.03M EDTA chelating agent

[0043] Electrolyte preparation: Using a 1 mol / L CH3COONa aqueous solution as the base electrolyte, add 0.03 mol / L EDTA powder to the base electrolyte and stir at room temperature until the EDTA is completely dissolved and the solution is homogeneous and transparent. The prepared electrolyte is labeled as 0.03MEDTA.

[0044] Magnesium-air batteries were assembled using the electrolyte prepared above. Tests were conducted at different current densities (1-10 mA / cm²). 2 Discharge performance testing (e.g.) will be conducted below. Figures 1-3 (As shown). Where, at 2.5 mA / cm 2 Under constant current density, the magnesium anode exhibits a discharge voltage of 1.73V, an anode utilization rate of 69.14%, and a specific capacity of 1503.14 mAh·g. -1 The energy density is 2594.95 mWh·g -1 Under the corresponding conditions, the control group had a voltage of 1.69V, an anode utilization rate of 50.31%, and a specific capacity of 1093.71 mAh·g. -1 The energy density is 1934.22 mWh·g -1 (like Figures 13-15 (As shown).

[0045] Example 2: Electrolyte containing 0.06M EDTA chelating agent

[0046] Electrolyte preparation: Using a 1 mol / L CH3COONa aqueous solution as the base electrolyte, add 0.06 mol / L EDTA powder to the base electrolyte and stir at room temperature until the EDTA is completely dissolved and the solution is homogeneous and transparent. The prepared electrolyte is labeled as 0.06MEDTA.

[0047] Magnesium-air batteries were assembled using the electrolyte prepared above. Discharge performance tests were conducted at different current densities (e.g., ...). Figures 4-6 (As shown). Where, at 1mA / cm 2 Under constant current density, the discharge voltage of the magnesium anode can reach 1.96V, while the control group voltage is 1.77V (e.g., Figures 13-15 (As shown).

[0048] Example 3: Electrolyte containing 0.02M DTPA chelating agent

[0049] Electrolyte preparation: Using a 1 mol / L CH3COONa aqueous solution as the base electrolyte, 0.02 mol / L DTPA powder was added to the base electrolyte and stirred at room temperature until the DTPA was completely dissolved and the solution was homogeneous and transparent. The prepared electrolyte was labeled as 0.02MDTPA.

[0050] Magnesium-air batteries were assembled using the electrolyte prepared above. Discharge performance tests were conducted at different current densities (e.g., ...). Figures 7-9 (As shown). At 2.5mA / cm 2 Under constant current density, the magnesium anode exhibits a discharge voltage of 1.67V, an anode utilization rate of 74.43%, and a specific capacity of 1618.14 mAh·g. -1 The energy density is 2698.21 mWh·g -1 Under the corresponding conditions, the control group had a voltage of 1.69V, an anode utilization rate of 50.31%, and a specific capacity of 1093.71 mAh·g. -1 The energy density is 1934.22 mWh·g -1 (like Figures 13-15 (As shown).

[0051] Example 4: Electrolyte containing 0.04M DTPA chelating agent

[0052] Electrolyte preparation: Using a 1 mol / L CH3COONa aqueous solution as the base electrolyte, 0.04 mol / L DTPA powder was added to the base electrolyte and stirred at room temperature until the DTPA was completely dissolved and the solution was homogeneous and transparent. The prepared electrolyte was labeled as 0.04MDTPA.

[0053] Magnesium-air batteries were assembled using the electrolyte prepared above. Discharge performance tests were conducted at different current densities (e.g., ...). Figure 10-12(As shown). Where, at 1mA / cm 2 Under constant current density, the discharge voltage of the magnesium anode can reach 1.96V, while the control group voltage is 1.77V (e.g., Figures 13-15 (As shown).

[0054] Comparative Example 1: 1 mol / L CH3COONa basic electrolyte

[0055] To prepare an aqueous solution of CH3COONa, 82.03 g of CH3COONa powder was weighed and placed in a beaker to prepare a 1 mol / L CH3COONa basic electrolyte.

[0056] Magnesium-air batteries were assembled using the electrolyte prepared above. Their discharge performance was tested at different current densities, and the results are as follows: Figures 13-15 As shown. At 2.5mA / cm 2 At a current density of 1.69V, with an anode utilization rate of 50.31%, the specific capacity is 1093.71 mAh·g. -1 The energy density is 1934.22 mWh·g -1 .

[0057] Performance comparison: as described in Examples 1-4 and Comparative Example 1. Figure 1 , 4 As shown in Figures 7, 10, and 13, the addition of chelating agents significantly improved the discharge voltage plateau (up to 1.96V compared to 1.77V for the base electrolyte). As described in the test results and corresponding figures of Examples 1, 3, and the comparative examples, the electrolytes with added EDTA or DTPA chelating agents exhibited significantly higher anode utilization, specific capacity, and energy density than the base electrolytes without added chelating agents.

[0058] In summary, the magnesium-air battery electrolytes containing organic chelating agents provided by this invention (Examples 1-4) exhibit higher discharge voltage, anode utilization, and specific capacity compared to sodium acetate-based electrolytes without such chelating agents (Comparative Example 1), and significantly improve the energy density of magnesium-air batteries. Based on this, this invention provides an organic carboxylate composite electrolyte containing organic chelating agents that can chelate metal ions and improve discharge uniformity, offering an effective electrolyte solution for developing magnesium-air batteries with high energy density, improved discharge voltage, and higher anode utilization.

Claims

1. An organic carboxylate-based electrolyte containing an organometallic ion chelating agent, characterized in that, Including deionized water, carboxylate electrolytes, and organometallic ion chelating agents; The organometallic ion chelating agent is an organic aminocarboxylic acid chelating agent.

2. An organic carboxylate-based electrolyte containing an organometallic ion chelating agent according to claim 1, characterized in that, The organic amino carboxyl chelating agent is selected from at least one of ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), ethylene glycol diethyl ether diaminetetraacetic acid (EGTA), and 1,2-cyclohexanediaminetetraacetic acid (CDTA).

3. An organic carboxylate-based electrolyte containing an organometallic ion chelating agent according to claim 1, characterized in that, The molar concentration of the organometallic ion chelating agent in the electrolyte is 0.01–0.1 mol / L.

4. An organic carboxylate-based electrolyte containing an organometallic ion chelating agent according to claim 1, characterized in that, The carboxylate electrolyte is selected from at least one of sodium formate, sodium acetate, sodium acetate trihydrate, potassium formate, potassium acetate, and potassium acetate trihydrate.

5. An organic carboxylate-based electrolyte containing an organometallic ion chelating agent according to claim 1, characterized in that, The molar concentration of the carboxylate electrolyte in the electrolyte is 0.5–1.5 mol / L.

6. An organic carboxylate-based electrolyte containing an organometallic ion chelating agent according to claim 1, characterized in that, The pH of the electrolyte was adjusted to 7.0 ± 0.2 using NaOH aqueous solution.

7. The application of the organic carboxylate-based electrolyte containing an organometallic ion chelating agent as described in any one of claims 1-6, in a magnesium-air battery.

8. A magnesium-air battery, characterized in that: It includes a magnesium anode, an air cathode, and the electrolyte as described in any one of claims 1-7.

9. A magnesium-air battery according to claim 8, characterized in that, The anode material is a Mg-1.5In-0.5Zn-0.2Ca (wt.%) alloy, and the cathode material consists of a multilayer structure composed of a C / MnO2 catalyst layer, a nickel foam mesh current collector, and a carbon cloth gas diffusion layer.

10. A magnesium-air battery according to claim 8 or 9, characterized in that, Magnesium-air batteries operate at current densities of 1–10 mA / cm². 2 .

Images