Amide electrolyte with hydrogen evolution inhibition function and application of amide electrolyte in flow battery

Abstract

The invention discloses an amide electrolyte with a hydrogen evolution inhibition function and an application of the amide electrolyte in a flow battery. The amide electrolyte is prepared by mixing salt containing metal ions with oxidation-reduction activity, supporting electrolyte, an amide additive and solvent water. According to the electrolyte provided by the invention, hydrogen evolution side reactions of various flow battery negative electrodes can be efficiently inhibited by utilizing the interface regulation and control effect of the amide type compound, the amide type additive does not generate negative effects on deposition / dissolution kinetics of negative electrode active ions of various battery systems, and normal reaction of negative electrode core couple can be ensured; and the coulombic efficiency and the cycling stability of various flow batteries are synchronously improved.

Description

Technical Field

[0001] This invention belongs to the field of battery energy storage technology, specifically relating to an amide-based electrolyte with hydrogen evolution inhibition function and its application in flow batteries. Background Technology

[0002] Flow batteries (including all-iron, all-vanadium, zinc-bromine, and iron-chromium types) are attracting significant attention as a highly promising large-scale energy storage technology due to their high system design flexibility, excellent safety, and energy-power decoupling characteristics. Different types of flow batteries, leveraging the advantages of high abundance of active materials, long cycle life, or high energy density, show broad application prospects in areas such as grid peak shaving, grid connection of renewable energy (such as wind and solar power), and distributed energy storage. Their core principle relies on the reaction of different active ion pairs at the positive and negative electrodes: for example, the positive electrode of an all-iron battery is Fe... 3+ / Fe 2+ negative electrode Fe 2+ / Fe 0 VO2, the positive electrode of a vanadium-based battery + / VO 2+ negative electrode V 3+ / V 2+ Zinc-bromine battery positive electrode Br2 / Br - Negative electrode Zn 2+ / Zn.

[0003] However, all types of flow batteries share a common problem at their negative electrodes—the hydrogen evolution side reaction: (Fe in all-iron batteries) 2+ Reduced, all-vanadium battery V 3+ Reduction, Zinc-Bromine Battery Zn 2+ Deposition, iron-chromium battery Cr 3+ Reduction occurs because the negative electrode reaction potential is close to the hydrogen evolution potential, leading to an increase in H+ in the electrolyte. + Electrons readily gain on the electrode surface to generate H2. This reaction not only consumes active charge and reduces coulombic efficiency, but also causes abnormal fluctuations in the electrolyte pH (e.g., in all-iron batteries). 2+ Hydrolysis and vanadium oxide precipitation in all-vanadium batteries; at the same time, the bubbles generated by hydrogen evolution adhere to the electrode surface, hindering the contact between active ions and the electrode, exacerbating the uneven deposition (such as zinc dendrites in zinc-bromine batteries and "dead iron" in all-iron batteries), posing a short circuit risk, and ultimately leading to a decline in the cycle performance and significant capacity decay of various flow batteries, restricting their efficiency improvement and large-scale commercial application. Summary of the Invention

[0004] The purpose of this invention is to provide an amide-based electrolyte with hydrogen evolution suppression function and its application in flow batteries. This invention adds amide-based additives to the electrolyte that can efficiently suppress hydrogen evolution side reactions at the negative electrode of various flow batteries, reducing active charge loss, improving coulombic efficiency, and significantly enhancing the cycle stability of the flow battery.

[0005] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is: an amide electrolyte with hydrogen evolution inhibition function, comprising a salt containing redox active metal ions, a supporting electrolyte, an amide additive, and water as solvent.

[0006] Furthermore, the salt is selected from iron salts, vanadium salts, zinc salts, or chromium salts.

[0007] Furthermore, the iron salt is selected from ferrous chloride, ferrous sulfate, or ferrous trifluoromethanesulfonate.

[0008] Furthermore, the vanadium salt is selected from vanadium oxysulfate, vanadium trichloride, or vanadium pentoxide.

[0009] Furthermore, the zinc salt is selected from zinc sulfate, zinc trifluoromethanesulfonate, zinc chloride, or zinc nitrate.

[0010] Furthermore, the chromium salt is selected from chromium sulfate, chromium nitrate, or chromium chloride.

[0011] Furthermore, when the salt is an iron salt, the iron salt concentration is 0.1 mol / L to 2.0 mol / L.

[0012] Furthermore, when the salt is a vanadium salt, the vanadium salt concentration is 0.1 mol / L to 3.0 mol / L.

[0013] Furthermore, when the salt is a zinc salt, the zinc salt concentration is 0.1 mol / L to 3.5 mol / L.

[0014] Furthermore, when the salt is a chromium salt, the chromium salt concentration is 0.1 mol / L to 3.0 mol / L.

[0015] Furthermore, the supporting electrolyte varies depending on the type of salt containing redox-active metal ions:

[0016] When the salt is an iron salt, the supporting electrolyte is selected from chlorides, sulfates, or trifluoromethanesulfonates. Preferably, the chloride can be potassium chloride, sodium chloride, or ammonium chloride; the sulfate can be potassium sulfate, sodium sulfate, or ammonium sulfate; and the trifluoromethanesulfonate can be lithium trifluoromethanesulfonate or potassium trifluoromethanesulfonate. One or more of these can be selected as needed.

[0017] When the salt is a vanadium salt, the supporting electrolyte is selected from hydrochloric acid, sulfuric acid, nitric acid, chloride, sulfate, or ammonium salt. Preferably, the chloride can be potassium chloride, sodium chloride, or ammonium chloride; the sulfate can be potassium sulfate, sodium sulfate, or ammonium sulfate; and the ammonium salt can be ammonium chloride, ammonium sulfate, or ammonium nitrate. One or more of these can be selected as needed.

[0018] When the salt is a zinc salt, the supporting electrolyte is selected from basic metal salts, sulfates, trifluoromethanesulfonates, acetates, or ammonium salts. Preferably, the basic metal salt can be sodium hydroxide or potassium hydroxide; the sulfate can be potassium sulfate, sodium sulfate, or ammonium sulfate; the trifluoromethanesulfonate can be lithium trifluoromethanesulfonate or potassium trifluoromethanesulfonate; the acetate can be sodium acetate, potassium acetate, or ammonium acetate; and the ammonium salt can be ammonium chloride or ammonium sulfate. One or more of these can be selected as needed.

[0019] When the salt is a chromium salt, the supporting electrolyte is selected from hydrochloric acid, sulfuric acid, nitric acid, sulfate, trifluoromethanesulfonate, or acetate. Preferred sulfates may be potassium sulfate, sodium sulfate, or ammonium sulfate; trifluoromethanesulfonates may be lithium trifluoromethanesulfonate or potassium trifluoromethanesulfonate; acetates may be sodium acetate, potassium acetate, or ammonium acetate; one or more of these can be selected as needed.

[0020] Furthermore, the amide additive is a compound with the general formula R-CONH2 or R-CONR'R'', wherein R, R', and R'' are independently selected from hydrogen, alkyl, alkenyl, or aryl.

[0021] Furthermore, the amide additive is selected from autolactam, propionamide, butyramide, benzamide, acetanilide, formamide, or acetamide.

[0022] Furthermore, the concentration of the amide additive is 0.1 mol / L to 4 mol / L.

[0023] This invention provides the application of an amide-based electrolyte with hydrogen evolution inhibition function as a negative electrode electrolyte in a flow battery.

[0024] Furthermore, the flow battery includes an all-iron flow battery, an all-vanadium flow battery, a zinc-bromine flow battery, and an iron-chromium flow battery.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1. The electrolyte provided by this invention utilizes the interfacial regulation effect of amide compounds to effectively suppress the hydrogen evolution side reaction at the negative electrode of various flow batteries. This is achieved through the interaction between the amide groups (-CONH-) in the amide compounds and H+. + Hydrogen bonding enhances H + The reduction overpotential, or the selective adsorption of its multi-ring structure on the electrode surface, accounts for H.+ The reactive sites effectively suppress hydrogen evolution side reactions by disrupting the hydrogen bond network between water molecules and / or participating in the solvation structure of metal ions.

[0027] 2. In this invention, amide additives will not have a negative impact on the deposition / dissolution kinetics of active ions in the negative electrode of each battery system, which can ensure the normal reaction of the core negative electrode couple and achieve simultaneous improvement in coulombic efficiency and cycle stability of various flow batteries.

[0028] 3. The amide additives introduced in this invention are low-cost and environmentally friendly, and do not introduce harmful substances, meeting the low-cost and green requirements of large-scale energy storage. This invention innovatively solves the common problems of low coulombic efficiency and short cycle life caused by hydrogen evolution side reactions in iron-based, vanadium-based, zinc-based, and chromium-based flow batteries, providing unified key technology support for the commercial application of various types of flow batteries.

[0029] In summary, by introducing an appropriate amount of amide additives into the negative electrode electrolyte, this invention can specifically suppress the hydrogen evolution side reaction of various flow battery negative electrodes, significantly improve the electrochemical stability of the negative electrode electrolyte, reduce energy loss, and improve cycle life and energy efficiency. Attached Figure Description

[0030] Figure 1 Linear voltammetry plots for Examples 1-3 and Comparative Example 1.

[0031] Figure 2 Linear voltammetry plots for Examples 4-6 and Comparative Example 2.

[0032] Figure 3 Linear voltammetry plots for Examples 7-9 and Comparative Example 3. Detailed Implementation

[0033] Examples 1-3: Iron-based amide electrolytes with hydrogen evolution inhibition function

[0034] I. Composition as follows

[0035] Amide electrolytes are made by mixing iron salt FeCl2 containing redox active iron ions, supporting electrolyte KCl, amide additive caprolactam (CPL), and deionized water.

[0036] The concentrations of FeCl2, KCl, and caprolactam (CPL) in amide electrolytes are shown in Table 1.

[0037] Table 1

[0038]

[0039] II. Preparation method is as follows

[0040] Dissolve the measured amount of FeCl2 in deionized water, add KCl and stir until completely dissolved, and finally add caprolactam (CPL). Continue stirring for 2-4 hours to obtain a homogeneous and transparent electrolyte.

[0041] Examples 4-6: Zinc-based amide electrolytes with hydrogen evolution inhibition function

[0042] I. Composition as follows

[0043] Amide electrolytes are made by mixing zinc salt ZnSO4 containing zinc ions with redox activity, supporting electrolyte NH4Cl, amide additive caprolactam (CPL), and deionized water.

[0044] The concentrations of ZnSO4, NH4Cl, and caprolactam (CPL) in amide electrolytes are shown in Table 2.

[0045] Table 2

[0046]

[0047] II. Preparation method is as follows

[0048] Dissolve the measured amount of ZnSO4 in deionized water, add NH4Cl and stir until completely dissolved, then add caprolactam (CPL) and continue stirring for 2-4 hours to obtain a homogeneous and transparent electrolyte.

[0049] Examples 7-9: Vanadium-based amide electrolytes with hydrogen evolution inhibition function

[0050] I. Composition as follows

[0051] Amide electrolytes are made by mixing vanadium salt VCl3 containing redox-active vanadium ions, supporting electrolyte H2SO4, amide additive caprolactam (CPL), and deionized water.

[0052] The concentrations of VCl3, H2SO4, and caprolactam (CPL) in amide electrolytes are shown in Table 3.

[0053] Table 3

[0054]

[0055] II. Preparation method is as follows

[0056] Dissolve the measured amount of VCl3 in deionized water, add H2SO4 and stir until completely dissolved, then add caprolactam (CPL) and continue stirring for 2-4 hours to obtain a homogeneous and transparent electrolyte.

[0057] Comparative Examples 1-3: Comparative Electrolytes

[0058] Comparative Example 1 Electrolyte: Prepared by mixing iron salt FeCl2 containing redox active iron ions, supporting electrolyte KCl, and deionized water. Concentrations are shown in Table 4.

[0059] Comparative Example 2 Electrolyte: Prepared by mixing zinc salt ZnSO4 containing zinc ions with redox activity, supporting electrolyte NH4Cl, and deionized water. Concentrations are shown in Table 4.

[0060] Comparative Example 3 Electrolyte: Prepared by mixing vanadium salt VCl3 containing redox-active vanadium ions, supporting electrolyte H2SO4, and deionized water. Concentrations are shown in Table 4.

[0061] Table 4

[0062]

[0063] Example 10 Electrochemical performance of amide electrolytes

[0064] The experiment used a three-electrode system for linear voltammetry testing, with a glassy carbon electrode as the working electrode, a platinum sheet as the counter electrode, and a mercurous sulfate electrode as the reference electrode. The scan rate was 10 mV / s.

[0065] I. Electrochemical performance of iron-based amide electrolytes

[0066] Methods: The electrolytes used were the electrolyte of Comparative Example 1 (1 mol / L KCl + 0.1 mol / L FeCl2) and the electrolytes of Examples 1-3 (1 mol / L KCl + 0.1 mol / L FeCl2 + 0.5 / 1 / 3 mol / L CPL). During testing, the three electrodes were immersed in the electrolyte, and the potential range was set to -1.6 V to -1.0 V (relative to the reference electrode). Linear sweep voltammetry was used for testing, and the results are as follows: Figure 1 .

[0067] like Figure 1 As shown, compared with the electrolyte of Comparative Example 1, the hydrogen evolution potential of the electrolytes of Examples 1-3 shifted significantly negatively, indicating that CPL can significantly inhibit hydrogen evolution in iron-based electrolytes, and the inhibitory effect increases with increasing CPL concentration.

[0068] II. Electrochemical Performance of Zinc-Based Amide Electrolytes

[0069] Methods: The electrolytes used were the electrolyte of Comparative Example 2 (1 mol / L NH4Cl + 0.1 mol / L ZnSO4) and the electrolytes of Examples 4-6 (1 mol / L NH4Cl + 0.1 mol / L ZnSO4 + 0.5 / 1 / 3 mol / L CPL). During testing, the three electrodes were immersed in the electrolyte, and the potential range was set to -2.4 V to -1.2 V (relative to the reference electrode). Linear sweep voltammetry was used for testing, and the results are as follows: Figure 2.

[0070] like Figure 2 As shown, compared with the electrolyte of Comparative Example 2, the hydrogen evolution potential of the electrolytes in Examples 4-6 shifted significantly negatively, indicating that CPL can significantly inhibit hydrogen evolution in zinc-based electrolytes, and the inhibitory effect increases with increasing CPL concentration.

[0071] III. Vanadium-based amide electrolytes

[0072] Methods: The electrolytes used were the electrolyte of Comparative Example 3 (0.5 mol / L H₂SO₄ + 0.1 mol / L VCl₃) and the electrolytes of Examples 7-9 (0.5 mol / L H₂SO₄ + 0.1 mol / L VCl₃ + 0.5 / 1 / 3 mol / L CPL). During testing, the three electrodes were immersed in the electrolyte, and the potential range was set to -1.25 V to -0.50 V (relative to the reference electrode). Linear sweep voltammetry was used for testing, and the results are as follows: Figure 3 .

[0073] like Figure 3 As shown, compared with the electrolyte of Comparative Example 3, the hydrogen evolution potential of the electrolytes in Examples 7-9 shifted significantly negatively, indicating that CPL can significantly inhibit hydrogen evolution in vanadium-based electrolytes, and the inhibitory effect increases with increasing CPL concentration.

[0074] In summary, this invention addresses the common pain point of hydrogen evolution side reaction at the negative electrode of various types of flow batteries, including iron-based, vanadium-based, and zinc-based batteries, and innovatively develops a negative electrode electrolyte using amides as additives. Its core advantages are clearly verified through LSV test data: compared to the blank system without additives, the addition of caprolactam significantly improves the performance of various active ions (Fe... 2+ / Zn 2+ / V 3+ / Cr 3+ The electrolytes all exhibited a significant negative shift in hydrogen evolution potential, fully demonstrating that caprolactam can increase the hydrogen evolution overpotential through a dual mechanism of hydrogen bonding and electrode interface adsorption, effectively suppressing hydrogen evolution side reactions. Simultaneously, the active ion reduction peak potential and current density in the linear voltammetry curves remained essentially stable, indicating that the additives do not interfere with the main reaction, ensuring the core performance of the battery. This electrolyte preparation process is simple, low-cost, and environmentally friendly, adaptable to different flow battery types and a wide operating range, providing key technical support for the commercial application of flow batteries in large-scale energy storage scenarios such as grid peak shaving and new energy grid connection, demonstrating significant engineering value and market prospects.

Claims

1. An amide-based electrolyte with hydrogen evolution inhibition function, characterized in that, The amide electrolyte comprises a salt containing redox-active metal ions, a supporting electrolyte, an amide additive and solvent water.

2. The amide electrolyte with hydrogen evolution inhibition function according to claim 1, characterized in that, The salt is selected from iron salt, vanadium salt, zinc salt or chromium salt.

3. The amide electrolyte with hydrogen evolution inhibition function according to claim 2, characterized in that, The iron salt is selected from ferrous chloride, ferrous sulfate or ferrous triflate; the vanadium salt is selected from vanadyl sulfate, vanadium trichloride or vanadium pentoxide; the zinc salt is selected from zinc sulfate, zinc triflate, zinc chloride or zinc nitrate; the chromium salt is selected from chromium sulfate, chromium nitrate or chromium chloride.

4. The amide electrolyte with hydrogen evolution inhibition function according to claim 3, characterized in that, When the salt is iron salt, the concentration of iron salt is 0.1-2.0 mol / L; when the salt is vanadium salt, the concentration of vanadium salt is 0.1-3.0 mol / L; when the salt is zinc salt, the concentration of zinc salt is 0.1-3.5 mol / L; when the salt is chromium salt, the concentration of chromium salt is 0.1-3.0 mol / L.

5. The amide electrolyte with hydrogen evolution inhibition function according to claim 4, characterized in that, When the salt is iron salt, the supporting electrolyte is selected from chloride, sulfate or triflate, and the concentration of the supporting electrolyte is 0.1-4.0 mol / L; when the salt is vanadium salt, the supporting electrolyte is selected from hydrochloric acid, sulfuric acid, nitric acid, chloride, sulfate or ammonium salt, and the concentration of the supporting electrolyte is 0.1-5.0 mol / L; when the salt is zinc salt, the supporting electrolyte is selected from metal basic salt, sulfate, triflate, acetate or ammonium salt, and the concentration of the supporting electrolyte is 0.1-3.0 mol / L; when the salt is chromium salt, the supporting electrolyte is selected from hydrochloric acid, sulfuric acid, nitric acid, sulfate, triflate or acetate, and the concentration of the supporting electrolyte is 0.1-3.0 mol / L.

6. The amide electrolyte with hydrogen evolution inhibition function according to any one of claims 1-5, characterized in that, The amide additive is a compound with general formula R-CONH2 or R-CONR'R'', wherein R, R' and R'' are independently selected from hydrogen, alkyl, alkenyl or aryl.

7. The amide electrolyte with hydrogen evolution inhibition function according to claim 6, characterized in that, The amide additive is selected from lactam, propionamide, butyramide, benzamide, acetanilide, formamide or acetamide.

8. The amide electrolyte with hydrogen evolution inhibition function according to claim 7, characterized in that, The concentration of the amide additive is 0.1-4.0 mol / L.

9. Use of the amide electrolyte with hydrogen evolution inhibition function according to any one of claims 1-8 as negative electrolyte in a flow battery.

10. Use according to claim 9, characterized in that, The flow battery comprises all-iron flow battery, all-vanadium flow battery, zinc-bromine flow battery and iron-chromium flow battery.

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