Preparation method and application of transition metal-bismuth composite electrode
By optimizing the electrolyte formulation and electrodeposition parameters, combined with an efficient pretreatment process, uniform co-deposition of transition metals and Bi was achieved, solving the preparation difficulties of flow battery electrode materials, improving electrode performance and stability, and meeting the needs of high-performance flow batteries.
Patent Information
- Application Number
- CN202510838104.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-23
- Publication Date
- 2025-09-19
AI Technical Summary
Existing methods for preparing flow battery electrode materials have problems such as insufficient electrode pretreatment, inaccurate control of deposition parameters, defects in the preparation process of Bi-based materials, and difficulties in transition metal-bismuth co-deposition, resulting in electrode performance that is difficult to meet the requirements of high-performance flow batteries.
By optimizing the electrolyte formulation and electrodeposition parameters, using metal salts, complexing agents and buffers in specific molar ratios, and combining efficient electrode pretreatment processes and inert atmosphere protection, uniform co-deposition of transition metals and Bi is achieved, the bonding strength between the deposited layer and the substrate is enhanced, and the A-Bi component ratio can be adjusted.
The active site density and binding force of the electrode were significantly improved, the uniform co-deposition of transition metals and Bi was achieved, and the energy efficiency and long-term cycle stability of the flow battery were improved. For example, the energy efficiency of the Cu-Bi composite electrode was 80% and the voltage efficiency was 82.8% at a current density of 240 mA/cm2.
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Abstract
Description
Technical Field
[0001] The present invention belongs to the field of liquid flow battery energy storage, and in particular relates to a preparation method and application of a transition metal-bismuth composite electrode. Background Art
[0002] In the field of flow battery energy storage, the performance of electrode materials has a decisive impact on the overall performance of the battery. Currently, electrodeposition technology is one of the mainstream methods for preparing electrode materials, but there are still many technical bottlenecks in practical application that urgently need to be broken through. Analysis of existing technologies and limitations:
[0003] (1) Insufficient electrode pretreatment
[0004] Traditional methods typically use acid washing or oxidation treatment to improve the surface properties of carbon-based materials (such as carbon felt, carbon cloth, and carbon paper). However, such treatments are difficult to effectively improve the surface roughness and active site density of the materials. Due to the strong inertness of the carbon-based surface, the adhesion between the deposited layer and the substrate is poor, resulting in uneven distribution of active materials, which in turn affects the conductivity and electrochemical stability of the electrode.
[0005] (2) Imprecise control of deposition parameters
[0006] During the electrodeposition process, the selection of the potential window is crucial for regulating the alloy composition. Improperly setting the potential window can easily cause the metal ratio in the deposited layer to deviate from the target value, affecting the electrode's catalytic activity. Furthermore, the balance between deposition rate and crystallinity remains a challenge: excessively fast deposition rates can lead to grain coarsening and reduce the electrode's specific surface area; while slow deposition rates can improve crystallinity, they suffer from low production efficiency, making it difficult to meet the demands of large-scale applications.
[0007] (3) Defects in the preparation process of bismuth (Bi)-based materials
[0008] The preparation of traditional bismuth-based materials (such as Bi alloys or Bi oxides) mainly relies on high-temperature alloying or chemical reduction methods, but these methods have obvious shortcomings; for example, high energy consumption: the high-temperature synthesis process consumes a lot of energy, which is not in line with the trend of green manufacturing; particle agglomeration: Bi is prone to sintering under high-temperature conditions, resulting in the aggregation of active particles and reducing the effective reaction area; uneven composition: the chemical reduction method is easily limited by reaction kinetics, resulting in uneven distribution of Bi and transition metals, affecting the stability of the electrode.
[0009] (4) Challenges of transition metal-bismuth co-deposition
[0010] During the electrodeposition process, the co-deposition of transition metals (such as Fe, Cu, Ni, etc.) and Bi is restricted by many factors: for example, it is difficult to control the ratio: the deposition potentials of different metals vary greatly, making it difficult to accurately control the alloy composition; the morphology is uncontrollable: the pH value, additives and impurities of the electrolyte will affect the microstructure of the deposited layer, leading to dendritic growth or loose porosity, reducing the mechanical strength and cycle life of the electrode; the process stability is poor: the repeatability between batches is low, making it difficult to meet the quality consistency requirements of industrial production.
[0011] To address the above problems, there is an urgent need to develop a new method for preparing transition metal-bismuth composite electrode materials to optimize the microstructure of the electrode, increase the density of active sites, and achieve precise control of composition and morphology, thereby significantly improving the energy efficiency and long-term cycle stability of flow batteries. Summary of the Invention
[0012] To address the shortcomings of the existing technology, the present invention addresses the key technical problem of electrode performance that struggles to meet the demands of high-performance flow batteries. This invention achieves uniform co-deposition of transition metals A-Bi by optimizing the electrolyte formulation (specific molar ratios of metal salts, complexing agents, and buffers) and electrodeposition parameters. It also enhances the bonding between the deposited layer and the substrate by proposing an efficient electrode pretreatment process ("pretreatment solution" activation followed by electrolyte infiltration). Finally, it provides a method for adjusting the A-Bi component ratio to meet application requirements, collaboratively and systematically addressing the aforementioned technical bottlenecks.
[0013] One aspect of the present invention provides a method for preparing a transition metal-bismuth composite electrode, comprising the steps of electrode pretreatment, electrolyte preparation, pre-adsorption treatment, and electrodeposition;
[0014] (1) The electrode pretreatment is as follows: immersing the carbon-based electrode in an acidic pretreatment solution, ultrasonically treating it at 30-60°C for 1-60 minutes, and then cleaning it with ultrapure water to remove surface impurities and introduce oxygen-containing functional groups to increase surface deposition active sites; the electrode pretreatment using a special acidic pretreatment solution can achieve improved performance of the liquid flow battery.
[0015] (2) The electrolyte is prepared as follows: ASO4:Bi2O3:Na3C6H5O7:NaBr in a molar ratio of 2:4:15:150 is dissolved in 1M HCl solvent and stirred until clear; sodium citrate (Na3C6H5O7) is used as a complexing agent to inhibit Bi 3 + hydrolysis, NaBr enhances the conductivity of the electrolyte, and ASO4 (Cu, Ni, Co, Mn) provides a metal source.
[0016] (3) Pre-adsorption treatment: The pretreated electrode is immersed in the electrolyte and ultrasonicated for 5-15 min to form a uniform ion adsorption layer on the surface of the carbon-based electrode, which promotes subsequent metal nucleation.
[0017] (4) Electrodeposition: Under the protection of an inert atmosphere, potential deposition is performed at 20-60°C to obtain an A-Bi composite electrode; wherein A is Cu, Ni, Fe or Mn.
[0018] Furthermore, the carbon-based electrode is one of carbon felt, carbon cloth or carbon paper.
[0019] Furthermore, the acidic pretreatment liquid is composed of B acid:H2O2 in a volume ratio of 5-10:1-5, and the B acid is selected from one of H2SO4, HNO3, and HClO4.
[0020] Furthermore, the inert atmosphere is at least one of argon, helium, and nitrogen, and the inert atmosphere is introduced throughout the entire process and the temperature is controlled at 20-60° C. to inhibit oxidation side reactions and improve the density of the deposited layer.
[0021] Furthermore, the electrodeposition process parameters are set as follows: the potential window is -15 to -20 mV vs. Ag / AgCl, and the deposition time is 1 to 30 min. By adjusting the deposition parameters, the reduction potential of metal A and the nucleation kinetics of Bi are taken into account to achieve co-deposition.
[0022] Furthermore, after the electrodeposition is completed, the A-Bi composite electrode is vacuum dried.
[0023] The second aspect of the present invention provides the use of the A-Bi composite electrode prepared by the above method in a vanadium redox flow battery.
[0024] The third aspect of the present invention provides an electrolyte for a transition metal-bismuth composite electrode, wherein the molar ratio of the components in the electrolyte is: ASO4:Bi2O3:Na3C6H5O7:NaBr=2:4:15:150, the solvent is 1M HCl, and A is Ni, Cu, Fe or Mn.
[0025] Compared with the prior art, the present invention has the following advantages:
[0026] 1. The present invention optimizes the electrolyte formula and adopts a specific molar ratio of metal salt, complexing agent and buffer, the specific molar ratio is ASO4:Bi2O3:Na3C6H5O7:NaBr=2:4:15:150, and the solvent is 1M HCl. Among them, ASO4 (Cu, Ni, Co, etc.) provides the metal source, and sodium citrate (Na3C6H5O7) acts as a complexing agent to inhibit Bi 3+ Hydrolysis of NaBr enhances the conductivity of the electrolyte, achieving uniform co-deposition of transition metal A and Bi, and solving the problem of uneven composition in traditional methods.
[0027] 2. The efficient electrode pretreatment process significantly improves the roughness and active site density of the carbon-based electrode surface, enhances the bonding force between the deposited layer and the substrate, and makes the deposited layer more evenly distributed.
[0028] 3. The adjustable A-Bi component ratio method can flexibly adjust the composition of the composite electrode material according to different application requirements, expanding its application range.
[0029] 4. When applied to vanadium flow batteries, the performance of the battery is significantly improved. For example, the Cu-Bi composite electrode sample has a high 2 The energy efficiency at the current density is 80%, and the voltage efficiency is 82.8%, while the energy efficiency of the blank carbon felt is 72.6% and the voltage efficiency is 74.3%, which is a significant improvement. BRIEF DESCRIPTION OF THE DRAWINGS
[0030] Figure 1 XRD test results of CuBi samples;
[0031] Figure 2 is the energy efficiency of CuBi and carbon felt blank samples at different current densities;
[0032] Figure 3 is the voltage efficiency of CuBi and carbon felt blank samples at different current densities;
[0033] Figure 4 is the XRD test result of Bi sample;
[0034] Figure 5 is the energy efficiency of CuBi and Bi samples at different current densities;
[0035] Figure 6 The voltage efficiency results of CuBi and Bi samples at different current densities;
[0036] Figure 7 is the XRD test result of Cu sample;
[0037] Figure 8 is the energy efficiency of CuBi and Cu samples at different current densities;
[0038] Figure 9 is the voltage efficiency of CuBi and Cu samples at different current densities. DETAILED DESCRIPTION
[0039] The present invention is described in detail below with reference to specific embodiments.
[0040] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several variations and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.
[0041] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.
[0042] Unless otherwise specified, the experimental materials and reagents used in the following examples were obtained from commercial sources.
[0043] The embodiments of the present invention will be described in detail below with reference to the examples, but it will be understood by those skilled in the art that the following examples are merely illustrative of the present invention and should not be construed as limiting the scope of the invention. Where specific conditions are not specified in the examples, the methods are carried out according to conventional conditions or the conditions recommended by the manufacturer. Unless otherwise stated, all reagents or instruments used can be commercially available.
[0044] Example 1: Preparation of Cu-Bi composite electrode
[0045] 1. Preparation of electrolyte: Weigh CuSO4 (2 mmol), Bi2O3 (4 mmol), Na3C6H5O7 (15 mmol), and NaBr (150 mmol) and dissolve them in 30 mL of 1 M HCl. Stir magnetically until the solution becomes clear.
[0046] 2. Electrode pretreatment: Cut carbon felt (5 cm × 5 cm) and immerse it in a pretreatment solution of HNO3:H2O2=6:5. Ultrasonicate it at 20-60 kHz for 30 min and then rinse it with ultrapure water.
[0047] 3. Pre-adsorption treatment: immerse the treated electrode in electrolyte for pre-ultrasonication for 10 minutes.
[0048] 4. Electrodeposition operation: Ar is passed through the electrolyte for 30 minutes, the temperature is maintained at 40°C, and a potential of -18 mV vs. Ag / AgCl is applied for deposition for 20 minutes. After deposition, the electrode is vacuum dried.
[0049] Cu-Bi composite electrode effect verification:
[0050] The prepared Cu-Bi composite electrode was subjected to XRD analysis. Figure 1 As shown, the XRD spectrum shows the characteristic peaks of CuBi metal complex and no oxide impurities.
[0051] Liquid flow battery performance tests show that: Figure 2-3 As shown, the Cu-Bi composite electrode sample is at 240 mA / cm2 The energy efficiency is 80% and the voltage efficiency is 82.8% at the current density, while the energy efficiency of blank carbon felt is 72.6% and the voltage efficiency is 74.3%.
[0052] Example 2: Bi electrode preparation
[0053] 1. Preparation of electrolyte: Weigh Bi2O3 (4 mmol), Na3C6H5O7 (15 mmol), and NaBr (150 mmol) and dissolve them in 30 mL 1 M HCl. Stir magnetically until the solution is clear.
[0054] 2. Electrode pretreatment: Cut carbon felt (5 cm × 5 cm) and immerse it in a pretreatment solution of HNO3:H2O2=6:5 under ultrasonic conditions of 20-60 kHz for 30 minutes, and then rinse it with ultrapure water.
[0055] 3. Pre-adsorption treatment: immerse the treated electrode in electrolyte for pre-ultrasonication for 10 minutes.
[0056] 4. Electrodeposition operation: pass Ar into the electrolyte for 30 minutes, maintain the temperature at 40°C, apply a potential of -18mV vs Ag / AgCl for 20 minutes, and vacuum dry the electrode after deposition.
[0057] Bi electrode effect verification:
[0058] The prepared pure Bi electrode was subjected to XRD analysis, as shown in Figure 4 As shown, the XRD spectrum shows the characteristic peaks of Bi metal and no oxide impurities.
[0059] Liquid flow battery performance tests show that: Figure 5-6 As shown, the Bi sample is at 240mA / cm 2 The energy efficiency is 77.8% and the voltage efficiency is 80.7% at the current density.
[0060] Example 3: Cu electrode preparation
[0061] 1. Preparation of electrolyte: Weigh CuSO4 (2 mmol), Na3C6H5O7 (15 mmol), and NaBr (150 mmol) and dissolve them in 30 mL 1 M HCl. Stir magnetically until the solution is clear.
[0062] 2. Electrode pretreatment: Cut carbon felt (5 cm × 5 cm) and immerse it in a pretreatment solution of HNO3:H2O2=6:5 for 30 minutes, then rinse it with ultrapure water and immerse it in electrolyte for 10 minutes.
[0063] 3. Pre-adsorption treatment: Immerse the treated electrode in electrolyte for 10 minutes. Electrodeposition operation
[0064] 4. Flow Ar into the electrolyte for 30 minutes, maintaining the temperature at 40°C. Apply a potential of -18 mV vs Ag / AgCl for 20 minutes, and vacuum dry the electrode after deposition.
[0065] Cu electrode effect verification:
[0066] The prepared pure Cu electrode was subjected to XRD analysis, as shown in Figure 7 As shown, the XRD spectrum shows the characteristic peaks of Cu metal and no oxide impurities.
[0067] Liquid flow battery performance tests show that: Figure 8-9 As shown, the Cu sample is at 240mA / cm 2 The energy efficiency is 76.5% and the voltage efficiency is 78.6% at the current density.
[0068] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various variations or modifications within the scope of the claims, which do not affect the essence of the present invention.
Claims
1. A method for preparing a transition metal-bismuth composite electrode, characterized in that: It includes electrode pretreatment, electrolyte preparation, pre-adsorption treatment and electrodeposition steps; (1) The electrode pretreatment is as follows: immersing the carbon-based electrode in an acidic pretreatment solution, ultrasonically treating the electrode at 30-60° C. for 1-60 min, and then cleaning the electrode with ultrapure water; (2) The electrolyte solution is prepared as follows: ASO4:Bi2O3:Na3C6H5O7:NaBr in a molar ratio of 2:4:15:150 is dissolved in 1M HCl solvent and stirred until clear; (3) Pre-adsorption treatment: The pre-treated electrode is immersed in an electrolyte and ultrasonicated for 5-15 min to form an ion adsorption layer on the surface of the carbon-based electrode; (4) Electrodeposition: Under the protection of an inert atmosphere, potential deposition is performed at 20-60°C to obtain an A-Bi composite electrode; wherein A is Cu, Ni, Fe or Mn.
2. The preparation method according to claim 1, characterized in that The carbon-based electrode is one of carbon felt, carbon cloth or carbon paper.
3. The preparation method according to claim 1, characterized in that The acidic pretreatment liquid is composed of B acid:H2O2 in a volume ratio of 5-10:1-5, and the B acid is selected from one of H2SO4, HNO3, and HClO4.
4. The preparation method according to claim 1, characterized in that The inert atmosphere is at least one of argon, helium, and nitrogen.
5. The preparation method according to claim 1, characterized in that Electrodeposition process parameter settings: potential window is -15~-20mVvs.Ag / AgCl, deposition time is 1-30min.
6. The preparation method according to claim 1, characterized in that After the electrodeposition is completed, the A-Bi composite electrode is vacuum dried.
7. Use of an A-Bi composite electrode prepared by the method according to any one of claims 1 to 6 in a vanadium redox flow battery.
8. An electrolyte for a transition metal-bismuth composite electrode, characterized in that: The molar ratio of the components in the electrolyte is: ASO4:Bi2O3:Na3C6H5O7:NaBr=2:4:15:150, the solvent is 1M HCl, and A is Ni, Cu, Fe or Mn.