Lead-bismuth alloy modified graphite felt, preparation method thereof and application of graphite felt in preparation of iron-chromium flow battery

Abstract

The invention relates to a lead-bismuth alloy modified graphite felt, a preparation method thereof and application of the lead-bismuth alloy modified graphite felt in preparation of an iron-chromium flow battery. Comprising the following steps: (1) soaking an original graphite felt in concentrated sulfuric acid to obtain an acid-treated graphite felt; (2) adding sodium pyrophosphate, L-tartaric acid, lead nitrate and bismuth nitrate (III) pentahydrate into the nitric acid solution, and carrying out ultrasonic oscillation to obtain a lead bismuth ion electro-deposition solution; and (3) soaking the acid-treated graphite felt in a lead bismuth ion electro-deposition solution, carrying out ultrasonic oscillation, and carrying out electro-deposition modification under constant voltage to obtain the lead bismuth alloy modified graphite felt. According to the preparation method, the graphite felt electrode is subjected to electro-deposition modification by using metal bismuth and lead, and bismuth can promote the oxidation-reduction reaction of chromium ions and also can enhance the reversibility of the reaction; the lead can effectively inhibit the hydrogen evolution reaction, so that the hydrogen evolution reaction is inhibited while the redox reaction strength of the negative electrode of the battery is promoted and the reversibility of the reaction is enhanced, the efficiency of the battery is improved, and the service life of the battery is prolonged.

Description

Technical Field

[0001] The invention relates to a lead-bismuth alloy modified graphite felt and a preparation method thereof and application thereof in preparing an iron-chromium liquid flow battery, belonging to the technical field of electrochemical energy storage. Background Art

[0002] With the development of science and technology and industry, fossil fuels have been increasingly questioned and resisted due to their own limitations and environmental pollution and damage. Renewable energy, as an environmentally friendly and efficient new energy source, has received more and more attention. However, due to the intermittent and volatile nature of renewable energy, large-scale energy storage equipment that is sufficiently stable and controllable is required to achieve sustainable use of energy. Liquid flow batteries have the advantages of high safety and stability, strong controllability, long cycle life, and environmental friendliness, and are considered to be one of the preferred technologies for large-scale energy storage equipment.

[0003] Liquid flow batteries are divided into positive and negative poles, separated by a semipermeable membrane in the middle. The positive and negative electrolytes are stored in external storage tanks, and circulate between the battery and the storage tank through the work of the pump in the working state. During the charge and discharge process, the electrolyte enters the battery from the storage tank, generates / consumes electrons on the electrode surface, and these electrons are transferred to the outside through the electrodes, thus completing the conversion between chemical energy and electrical energy. According to the different substances that undergo redox reactions at the positive and negative electrodes, they can be divided into multiple categories. Among them, all-vanadium liquid flow batteries and iron-chromium liquid flow batteries are the most widely studied and used due to their excellent performance. However, due to the relatively high price of vanadium, all-vanadium liquid flow batteries are difficult to promote for commercial application, while iron-chromium liquid flow battery materials are relatively cheap and have unique commercial advantages. However, the Cr in the negative electrode of the iron-chromium liquid flow battery 3+ / Cr 2+ The redox reaction has poor reversibility, low activity and is prone to hydrogen evolution reaction, which is the primary problem restricting the development and application of this battery.

[0004] In order to solve the above problems, people have made great efforts in recent years, mainly by developing and improving electrolytes, membranes and electrodes. Among them, the electrode is one of the key materials of liquid flow batteries, and it is also the main place where electrochemical reactions occur, providing channels for transporting electrons. The polarization loss of the battery includes electrochemical polarization, ohmic polarization and concentration polarization. The above polarization losses determine the performance of the battery electrode and affect the Coulomb efficiency and current density of the liquid flow battery. The ideal electrode needs to have high electrochemical activity and reaction reversibility, enhance the electrode reaction rate to reduce electrochemical polarization loss, high conductivity to reduce ohmic polarization loss, high specific surface area, suitable porosity, and increase the ion diffusion rate to reduce concentration polarization loss.

[0005] Doping metal atoms on the electrode surface can provide more active sites for electrode reactions, reduce electrode polarization, and have strong catalytic activity and stability. It is one of the mainstream methods of electrode modification. In metal-modified electrodes, the commonly used metals are mostly precious metals such as Pt and Au, which increases the cost of the battery and loses the advantages of the iron-chromium flow battery itself. Selecting two or more metals to make alloys is one of the best ways to replace precious metals and reduce costs. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention provides a lead-bismuth alloy modified graphite felt and a preparation method thereof and an application thereof in the preparation of an iron-chromium flow battery. The present invention dopes a lead-bismuth alloy into a graphite felt substrate by an electrodeposition method to form a lead-bismuth alloy modified graphite felt, which can be used as an electrode of an iron-chromium flow battery, and can promote the intensity of the redox reaction of the negative electrode of the iron-chromium flow battery and inhibit the occurrence of its hydrogen evolution reaction.

[0007] The technical solution of the present invention is as follows:

[0008] A method for preparing lead-bismuth alloy modified graphite felt comprises the following steps:

[0009] (1) Acid treatment of graphite felt electrode: soak the original graphite felt in concentrated sulfuric acid, take it out, wash it and dry it to obtain acid-treated graphite felt;

[0010] (2) Preparation of lead-bismuth ion electrodeposition solution: adding sodium pyrophosphate, L-tartaric acid, lead nitrate, and bismuth (III) nitrate pentahydrate to a nitric acid solution, followed by ultrasonic treatment to obtain a lead-bismuth ion electrodeposition solution;

[0011] (3) Electroplating modification of acid-treated graphite felt: The acid-treated graphite felt obtained in step (1) is immersed in the lead-bismuth ion electroplating solution obtained in step (2), subjected to ultrasonic oscillation treatment, and then subjected to electroplating modification of the acid-treated graphite felt using a three-electrode system at a constant voltage. After the electroplating modification is completed, the graphite felt is cleaned and dried to obtain a lead-bismuth alloy-modified graphite felt.

[0012] According to the preferred embodiment of the present invention, in step (1), the concentration of the concentrated sulfuric acid is 98%, and the soaking time is 8 to 12 hours. The impurities on the surface of the graphite felt can be removed and etched by acid soaking, thereby increasing the specific surface area and oxygen-containing functional groups of the graphite felt.

[0013] Further preferably, the soaking time is 10 hours.

[0014] Preferably, in step (1), the cleaning and drying are as follows: first cleaning with deionized water for 3 times, and then drying at 100-120° C. for 0.5-1 h.

[0015] Preferably, according to the present invention, in step (2), the concentration of the nitric acid solution is 5 mol / L, and the molar ratio of lead ions to bismuth ions in the lead-bismuth ion electrodeposition solution is (1-3): (1-3).

[0016] Further preferably, for a graphite felt having an area of ​​1.5*1.5 cm, the added amounts of the sodium pyrophosphate, L-tartaric acid, lead nitrate, and bismuth (III) nitrate pentahydrate are respectively: 3 g sodium pyrophosphate, 0.161 g L-tartaric acid, 0.662 g lead nitrate, and 2.910 g bismuth (III) nitrate pentahydrate, and the volume of the nitric acid solution is 50 mL; the molar ratio of lead ions to bismuth ions in the lead-bismuth ion electrodeposition solution is 1:3.

[0017] Preferably, according to the present invention, in step (2), the ultrasonic oscillation treatment time is 10 to 30 minutes.

[0018] Preferably, according to the present invention, in step (3), the ultrasonic oscillation treatment time is 5 to 15 minutes.

[0019] Preferably according to the present invention, in step (3), the constant voltage is -1 to -0.5V.

[0020] Further preferably, the constant voltage is -0.8V.

[0021] According to the preferred embodiment of the present invention, in step (3), the working electrode in the three-electrode system is an acid-treated graphite felt, the counter electrode is a platinum sheet electrode, and the reference electrode is a saturated calomel electrode. The lead-bismuth ions in the electrodeposition solution can be reduced on the surface of the graphite felt by electrodeposition modification of the three-electrode system. Since metal bismuth is easy to form alloys with other metals, the lead-bismuth ions on the surface of the graphite felt are reduced to lead-bismuth alloys.

[0022] Preferably according to the present invention, in step (3), the electrodeposition modification time is 30 to 100 seconds.

[0023] Further preferably, the electrodeposition modification time is 50 s.

[0024] Preferably, in step (3), the cleaning and drying are as follows: firstly rinsing with anhydrous ethanol and deionized water three times in sequence, and then drying at 100-120° C. for 0.5-1 h.

[0025] A lead-bismuth alloy modified graphite felt is prepared according to the method.

[0026] The above-mentioned lead-bismuth alloy modified graphite felt is used as an electrode of an iron-chromium liquid flow battery in the preparation of an iron-chromium liquid flow battery.

[0027] Technical features and beneficial effects of the present invention:

[0028] 1. The present invention utilizes metal bismuth and metal lead to perform electrodeposition modification on graphite felt electrodes. Metal bismuth can not only promote the redox reaction of chromium ions, but also greatly enhance the reversibility of the reaction; metal lead can effectively inhibit the occurrence of hydrogen evolution reaction. Therefore, the lead-bismuth alloy modified graphite felt provided by the present invention can be used as an electrode of an iron-chromium liquid flow battery. While promoting the intensity of the redox reaction of the negative electrode of the battery and enhancing the reversibility of the reaction, it can inhibit the occurrence of hydrogen evolution reaction, thereby reducing polarization loss and improving battery efficiency and life.

[0029] 2. Compared with the existing modification method of reducing metal oxides to metals by electrochemical deoxidation, the preparation method of lead-bismuth alloy modified graphite felt provided by the present invention has a simpler production process and high operational safety. The electro-deoxidation method only simply reduces bimetallic oxides to bimetals, while the electro-reduction method can reduce bimetallic ions to metal alloys with more stable structural properties.

[0030] 3. The lead-bismuth alloy modified graphite felt prepared by the present invention can provide more reactive sites for the negative electrode redox reaction, enhance the reaction intensity and reversibility, reduce polarization loss, and improve the electrochemical performance of the electrode. At the same time, it can also increase the precipitation potential of the negative electrode hydrogen evolution reaction, thereby inhibiting the hydrogen evolution reaction and improving the battery efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is the SEM morphology of the lead-bismuth alloy modified graphite felt prepared in Example 1 of the present invention.

[0032] Figure 2 This is the mapping result of the lead-bismuth alloy modified graphite felt prepared in Example 1 of the present invention.

[0033] Figure 3 It is a cyclic voltammetry curve of the lead-bismuth alloy modified graphite felt prepared in Example 1 of the present invention.

[0034] Figure 4 It is a cyclic voltammetry curve of the lead-bismuth alloy modified graphite felt prepared in Example 2 of the present invention.

[0035] Figure 5 It is a cyclic voltammetry curve of the lead-bismuth alloy modified graphite felt prepared in Example 3 of the present invention.

[0036] Figure 6 It is a slow linear sweep voltammetry curve of the lead-bismuth alloy modified graphite felt prepared in Example 1 of the present invention.

[0037] Figure 7 It is a slow linear sweep voltammetry curve of the lead-bismuth alloy modified graphite felt prepared in Example 2 of the present invention.

[0038] Figure 8 It is a slow linear sweep voltammetry curve of the lead-bismuth alloy modified graphite felt prepared in Example 3 of the present invention.

[0039] Fig. 9 This is the electrochemical impedance diagram of the lead-bismuth alloy modified graphite felt prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0040] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0041] The experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.

[0042] Example 1

[0043] A method for preparing lead-bismuth alloy modified graphite felt comprises the following steps:

[0044] (1) Acid treatment of graphite felt electrode: soak the original graphite felt of 1.5*1.5 cm in 98% concentrated sulfuric acid solution for 10 h, then wash it with deionized water for 3 times, and then dry it in a drying oven at 120°C for 1 h to obtain acid-treated graphite felt; (2) Preparation of metal alloy electrodeposition solution: add 3 g of sodium pyrophosphate, 0.161 g of L-tartaric acid, 0.662 g of lead nitrate, and 2.910 g of bismuth (III) nitrate pentahydrate to 50 mL of 5 mol / L nitric acid solution, and then ultrasonically shake it for 10 min to fully dissolve the solid powder to obtain lead bismuth ion electrodeposition solution;

[0045] Wherein, the molar ratio of lead ions to bismuth ions in the lead-bismuth ion electrodeposition solution is 1:3;

[0046] (3) Electrodeposition modification of acid-treated graphite felt: The acid-treated graphite felt obtained in step (1) was immersed in the lead-bismuth ion electrodeposition solution obtained in step (2), and subjected to ultrasonic oscillation for 5 min. Then, the acid-treated graphite felt was subjected to electrodeposition modification using a three-electrode system at a constant voltage of -0.8 V. After electrodeposition modification for 50 s, the graphite felt was taken out and rinsed three times with anhydrous ethanol and deionized water in sequence. Finally, the graphite felt was dried in a drying oven at 120° C. for 1 h to obtain a lead-bismuth alloy-modified graphite felt.

[0047] Wherein, in the three-electrode system, the working electrode is an acid-treated graphite felt, the counter electrode is a platinum sheet electrode, and the reference electrode is a saturated calomel electrode.

[0048] The microstructure of the lead-bismuth alloy modified graphite felt obtained in this example is as follows: Figure 1 The specific material composition is as shown in Figure 2 shown.

[0049] Depend on Figure 1 It can be seen that the surface of the lead-bismuth alloy modified graphite felt carbon fiber of the present invention is grooved, which is due to the etching effect of sulfuric acid, which increases the specific surface area of ​​the graphite felt and enhances its hydrophilicity; the sediment is deposited in blocks and evenly deposited on the surface of the graphite felt carbon fiber.

[0050] Depend on Figure 2 It can be seen that the blocky deposits on the surface of the lead-bismuth alloy graphite felt fiber of the present invention are lead-bismuth elements, and the positions of the lead-bismuth elements are highly overlapped, which can prove that the blocky deposits are lead-bismuth alloy.

[0051] Example 2

[0052] A method for preparing lead-bismuth alloy modified graphite felt comprises the following steps:

[0053] (1) Acid treatment of graphite felt electrode: soak the original graphite felt of 1.5*1.5 cm in 98% concentrated sulfuric acid solution for 10 h, then wash it with deionized water for 3 times, and then dry it in a drying oven at 120°C for 1 h to obtain acid-treated graphite felt; (2) Preparation of lead-bismuth ion electrodeposition solution: add 3 g of sodium pyrophosphate, 0.161 g of L-tartaric acid, 1.325 g of lead nitrate, and 1.940 g of bismuth (III) nitrate pentahydrate to 50 mL of 5 mol / L nitric acid solution, and then ultrasonically shake it for 10 min to fully dissolve the solid powder to obtain lead-bismuth ion electrodeposition solution;

[0054] Wherein, the molar ratio of lead ions to bismuth ions in the lead-bismuth ion electrodeposition solution is 1:1;

[0055] (3) Electrodeposition modification of acid-treated graphite felt: The acid-treated graphite felt obtained in step (1) was immersed in the lead-bismuth ion electrodeposition solution obtained in step (2), and subjected to ultrasonic oscillation for 5 min. Then, the acid-treated graphite felt was subjected to electrodeposition modification using a three-electrode system at a constant voltage of -0.8 V. After electrodeposition modification for 50 s, the graphite felt was taken out and rinsed three times with anhydrous ethanol and deionized water in sequence. Finally, the graphite felt was dried in a drying oven at 120° C. for 1 h to obtain a lead-bismuth alloy-modified graphite felt.

[0056] Wherein, in the three-electrode system, the working electrode is an acid-treated graphite felt, the counter electrode is a platinum sheet electrode, and the reference electrode is a saturated calomel electrode.

[0057] Example 3

[0058] A method for preparing lead-bismuth alloy modified graphite felt comprises the following steps:

[0059] (1) Acid treatment of graphite felt electrode: 1.5*1.5 cm original graphite felt was soaked in 98% concentrated sulfuric acid solution for 10 h, then washed with deionized water for 3 times, and then placed in a drying oven at 120° C. for 1 h to obtain acid-treated graphite felt;

[0060] (2) Preparation of lead-bismuth ion electrodeposition solution: add 3 g of sodium pyrophosphate,

[0061] 0.161 g of L-tartaric acid, 1.987 g of lead nitrate, and 0.970 g of bismuth (III) nitrate pentahydrate were added, and then ultrasonically shaken for 10 minutes to fully dissolve the solid powder to obtain a lead-bismuth ion electrodeposition solution;

[0062] Wherein, the molar ratio of lead ions to bismuth ions in the lead-bismuth ion electrodeposition solution is 3:1;

[0063] (3) Electrodeposition modification of acid-treated graphite felt: The acid-treated graphite felt obtained in step (1) was immersed in the metal alloy electrodeposition solution obtained in step (2), and subjected to ultrasonic oscillation for 5 min. Then, the acid-treated graphite felt was subjected to electrodeposition modification using a three-electrode system at a constant voltage of -0.8 V. After electrodeposition modification for 50 s, the graphite felt was taken out and rinsed three times with anhydrous ethanol and deionized water in sequence. Finally, the graphite felt was dried in a drying oven at 120° C. for 1 h to obtain a lead-bismuth alloy-modified graphite felt.

[0064] Wherein, in the three-electrode system, the working electrode is an acid-treated graphite felt, the counter electrode is a platinum sheet electrode, and the reference electrode is a saturated calomel electrode.

[0065] Comparative Example 1

[0066] An acid-treated graphite felt is prepared according to the method described in step (1) of Example 1.

[0067] Test Example 1

[0068] 1. Cyclic voltammetry test was carried out on the lead-bismuth alloy modified graphite felt prepared in Example 1 and the acid-treated graphite felt in Comparative Example 1. The specific test was carried out in a three-electrode electrolytic cell consisting of the lead-bismuth alloy modified graphite felt in Example 1, a Pt sheet and a saturated calomel as the working electrode, the counter electrode and the reference electrode, respectively, and the electrolyte solution was a mixed solution of 1 mol / L FeCl3+1 mol / L CrCl2+3 mol / L HCl.

[0069] The cyclic voltammetry curves of the lead-bismuth alloy modified graphite felt prepared in Example 1 and the acid-treated graphite felt in Comparative Example 1 are as follows: Figure 3 shown.

[0070] Depend on Figure 3It can be seen that the graphite felt treated only by acidification exhibits poor reversibility and no reduction peak appears; while the lead-bismuth alloy modified graphite felt not only has better reversibility performance, but also the intensity of the redox peak potential is enhanced.

[0071] 2. Cyclic voltammetry test was carried out on the lead-bismuth alloy modified graphite felt prepared in Example 2. The specific test was carried out in a three-electrode electrolytic cell consisting of the lead-bismuth alloy modified graphite felt in Example 2, a Pt sheet and a saturated calomel as the working electrode, the counter electrode and the reference electrode, respectively, and the electrolyte solution was a mixed solution of 1 mol / L FeCl3+1 mol / L CrCl2+3 mol / L HCl.

[0072] Example 2 The cyclic voltammetry curve of lead-bismuth alloy modified graphite felt is as follows Figure 4 shown.

[0073] 3. Cyclic voltammetry test was carried out on the lead-bismuth alloy modified graphite felt prepared in Example 3. The specific test was carried out in a three-electrode electrolytic cell consisting of the lead-bismuth alloy modified graphite felt in Example 3, a Pt sheet and a saturated calomel as the working electrode, the counter electrode and the reference electrode, respectively, and the electrolyte solution was a mixed solution of 1 mol / L FeCl3+1 mol / L CrCl2+3 mol / L HCl.

[0074] Example 3 The cyclic voltammetry curve of lead-bismuth alloy modified graphite felt is as follows Figure 5 shown.

[0075] pass Figures 3 to 5 By comparison, it can be concluded that the redox reaction of the lead-bismuth alloy modified graphite felt in Example 1 occurs first, and the reduction reaction intensity is the strongest. Figures 3 to 5 The data are shown in Table 1 below.

[0076] Table 1

[0077]

[0078]

[0079] As shown in Table 1, from the perspective of reversibility, although the ΔE value of the lead-bismuth alloy modified graphite felt in Example 1 is not the lowest value, its (I pa / I pc -1) is significantly lower than that of the other two samples, and still shows the best reversibility. Therefore, on the whole, the lead-bismuth alloy modified graphite felt in Example 1 has the highest redox reaction efficiency at the negative electrode.

[0080] Test Example 2

[0081] 1. Slow linear sweep voltammetry test was performed on the lead-bismuth alloy modified graphite felt prepared in Example 1 and the acid-treated graphite felt in Comparative Example 1. The specific test was carried out in a three-electrode electrolytic cell consisting of the lead-bismuth alloy modified graphite felt in Example 1, a Pt sheet and saturated calomel as the working electrode, the counter electrode and the reference electrode, respectively, and the electrolyte solution was HCl with a concentration of 3 mol / L.

[0082] The slow linear sweep voltammetry curves of the lead-bismuth alloy modified graphite felt prepared in Example 1 and the acid-treated graphite felt in Comparative Example 1 are as follows: Figure 6 shown.

[0083] Depend on Figure 6 It can be seen that the hydrogen evolution reaction of the graphite felt treated only by acidification is the most rapid and intense, and the hydrogen evolution reaction has occurred at the potential at the beginning of the scan. The hydrogen evolution reaction of the lead-bismuth alloy modified graphite felt is significantly inhibited, and the hydrogen evolution reaction potential is increased.

[0084] 2. A slow linear sweep voltammetry test was performed on the lead-bismuth alloy modified graphite felt prepared in Example 2. The specific test was performed in a three-electrode electrolytic cell consisting of the lead-bismuth alloy modified graphite felt in Example 2, a Pt sheet and saturated calomel as the working electrode, the counter electrode and the reference electrode, respectively, and the electrolyte solution was HCl with a concentration of 3 mol / L.

[0085] The slow linear sweep voltammetry curve of the lead-bismuth alloy modified graphite felt prepared in Example 2 is as follows: Figure 7 shown.

[0086] 3. A slow linear sweep voltammetry test was performed on the lead-bismuth alloy modified graphite felt prepared in Example 3. The specific test was performed in a three-electrode electrolytic cell consisting of the lead-bismuth alloy modified graphite felt in Example 3, a Pt sheet and saturated calomel as the working electrode, the counter electrode and the reference electrode, respectively, and the electrolyte solution was HCl with a concentration of 3 mol / L.

[0087] The slow linear sweep voltammetry curve of the lead-bismuth alloy modified graphite felt prepared in Example 3 is as follows: Figure 8 shown.

[0088] pass Figures 6 to 8 By comparison, it can be concluded that the potentials of the three lead-bismuth alloy modified graphite felts for hydrogen evolution reaction are similar. 2 When the overpotential of the lead-bismuth alloy modified graphite felt of Example 1, Example 2, and Example 3 for hydrogen evolution reaction is -0.58 V, -0.58 V, and -0.54 V, respectively. The inhibitory effect of the hydrogen evolution reaction of the lead-bismuth alloy modified graphite felt of Example 1 is not much different from that of the other samples.

[0089] Test Example 3

[0090] Electrochemical impedance spectroscopy tests were carried out on the lead-bismuth alloy modified graphite felt and the original graphite felt prepared in Example 1. The specific tests were as follows: the tests were carried out in a three-electrode electrolytic cell consisting of the lead-bismuth alloy modified graphite felt in Example 1, a Pt sheet and a saturated calomel as the working electrode, the counter electrode and the reference electrode, respectively, and the electrolyte solution was a mixed solution of 1 mol / L FeCl3+1 mol / L CrCl2+3 mol / L HCl.

[0091] The electrochemical impedance spectroscopy of the lead-bismuth alloy modified graphite felt and the original graphite felt prepared in Example 1 is as follows: Fig. 9 shown.

[0092] Depend on Fig. 9 It can be seen that compared with the original graphite felt, the total impedance of the lead-bismuth alloy modified graphite felt in Example 1 is significantly smaller than that of the original graphite felt, the polarization loss is significantly reduced, and the dynamic performance is better.

[0093] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations. Although the present invention has been described above through embodiments, those skilled in the art should understand that, without departing from the spirit and essence of the present invention, the improvements and variations made to the present invention should all fall within the scope of protection of the present invention.

Claims

1. A method for preparing lead-bismuth alloy modified graphite felt, characterized in that: The following steps are involved: (1) Acid treatment of graphite felt electrode: soak the original graphite felt in concentrated sulfuric acid, take it out, wash it and dry it to obtain acid-treated graphite felt; (2) Preparation of lead-bismuth ion electrodeposition solution: adding sodium pyrophosphate, L-tartaric acid, lead nitrate, and bismuth (III) nitrate pentahydrate to a nitric acid solution, followed by ultrasonic treatment to obtain a lead-bismuth ion electrodeposition solution; (3) Electroplating modification of acid-treated graphite felt: The acid-treated graphite felt obtained in step (1) is immersed in the lead-bismuth ion electroplating solution obtained in step (2), subjected to ultrasonic oscillation treatment, and then subjected to electroplating modification of the acid-treated graphite felt using a three-electrode system at a constant voltage. After the electroplating modification is completed, the graphite felt is cleaned and dried to obtain a lead-bismuth alloy-modified graphite felt.

2. The preparation method according to claim 1, characterized in that In step (1), the concentration of the concentrated sulfuric acid is 98%, and the soaking time is 8 to 12 hours; Further preferably, the soaking time is 10 hours.

3. The preparation method according to claim 1, characterized in that: In step (1) and step (3), the cleaning and drying are specifically as follows: first cleaning with deionized water for 3 times, and then drying at 100-120° C. for 0.5-1 h.

4. The preparation method according to claim 1, characterized in that: In step (2), the concentration of the nitric acid solution is 5 mol / L, and the molar ratio of lead ions to bismuth ions in the lead-bismuth ion electrodeposition solution is (1-3): (1-3).

5. The preparation method according to claim 1, characterized in that: For a graphite felt of 1.5*1.5cm, the added amounts of the sodium pyrophosphate, L-tartaric acid, lead nitrate, and bismuth (III) nitrate pentahydrate are respectively: 3g sodium pyrophosphate, 0.161g L-tartaric acid, 0.662g lead nitrate, and 2.910g bismuth (III) nitrate pentahydrate, and the volume of the nitric acid solution is 50mL; the molar ratio of lead ions to bismuth ions in the lead-bismuth ion electrodeposition solution is 1:

3.

6. The preparation method according to claim 1, characterized in that: In step (3), the constant voltage is -1 to -0.5 V; Further preferably, the constant voltage is -0.8V.

7. The preparation method according to claim 1, characterized in that: In step (3), in the three-electrode system, the working electrode is acid-treated graphite felt, the counter electrode is a platinum sheet electrode, and the reference electrode is a saturated calomel electrode.

8. The preparation method according to claim 1, characterized in that: The preparation method according to claim 1, characterized in that in step (3), the electrodeposition modification time is 30 to 100 seconds; Further preferably, the electrodeposition modification time is 50 s.

9. A lead-bismuth alloy modified graphite felt, characterized in that: It is prepared according to the method according to any one of claims 1 to 8.

10. Use of the lead-bismuth alloy modified graphite felt according to claim 9 as an electrode of an iron-chromium liquid flow battery in the preparation of an iron-chromium liquid flow battery.

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