Preparation method of copper vacancy copper hexacyanoferrate and multivalent aqueous battery

Abstract

The application provides a preparation method of a copper vacancy-containing copper hexacyanoferrate (CuHCF-V) material and a method for applying the material to various aqueous ion batteries. Specifically, the copper vacancy-containing CuHCF-V material is prepared by a one-step coprecipitation method, and is applied to a multivalent ion battery in 4, including a zinc ion battery, a magnesium ion battery, an aluminum ion battery and a calcium ion battery, while the electrochemical initial specific capacity and the cycle performance are improved.

Description

Technical Field

[0001] This invention belongs to the field of materials preparation and relates to a method for preparing a copper-vacancy copper hexacyanoferrite electrode material and a multivalent aqueous ion battery. Background Technology

[0002] Copper hexacyanoferrite (CuHCF) belongs to the open-framework Prussian blue analogues (PBAs). It has the characteristics of low cost, simple synthesis, and large ion channels, and is one of the commonly used cathode materials in the field of energy storage.

[0003] Aqueous batteries are promising energy storage devices due to their high safety, low cost, and high ionic conductivity. Among them, multivalent cations (Ca)... 2+ Zn 2+ Mg 2+ Al 3+ Batteries have attracted widespread attention due to their abundant reserves, low cost, and ability to transfer more charge, thus achieving higher energy density.

[0004] However, the stronger electrostatic interactions between multivalent cations and electrode materials lead to slower kinetic processes, and the large volume expansion caused by ion insertion / extraction results in lattice collapse and exfoliation of the electrode material, leading to poor cycle life. These factors hinder the further development of multivalent ion batteries. To address these issues, many strategies have been proposed, including introducing vacancies, mixing with other conductive materials, pre-intercalation, and optimizing the electrolyte. Among these, cation vacancies are an effective means to improve electrode electrochemical performance because they can increase ion intercalation space, increase available active sites, and reduce the interaction between intercalated ions and electrode materials. However, they often require complex synthesis processes, increasing the cost of material preparation and making it difficult to apply to other multivalent ion batteries. Summary of the Invention

[0005] This application provides a method for preparing copper hexacyanoferrite (CuHCF-V) electrode materials containing copper vacancies. By introducing copper vacancies into the copper hexacyanoferrite (CuHCF) cathode material, the method aims to alleviate the volume expansion problem caused by multivalent ions during long-term cycling, effectively improve crystal structure stability, thereby achieving a higher cycle life, and making it suitable for various aqueous ion batteries (Ca). 2+ Zn 2+ Mg 2+ Al 3+ ).

[0006] This invention employs the following technical solution: a method for preparing copper hexacyanoferrite (CuHCF-V) electrode materials containing copper vacancies, including but not limited to a simple one-step co-precipitation method. The method involves simultaneously adding solution A and solution B dropwise to deionized water. After the addition is complete, the solution is allowed to stand at room temperature for 12 hours, centrifuged, and then vacuum dried to obtain CuHCF-V material with a blocky morphology of less than 500 nm in size. Solution A is a mixed solution of copper chloride and EDTA, and solution B is a potassium ferricyanide solution. The copper chloride, potassium ferricyanide, and EDTA are prepared according to a molar ratio of iron, copper, and EDTA of 50:100:6.

[0007] In solution A, the concentration of ethylenediaminetetraacetic acid (EDTA) is 3-10 mmol / L. -1 The preferred value is 6 mmol / L. -1 .

[0008] In an embodiment of the present invention, the following preparation method is provided: 120 mL of solution A and 120 mL of solution B are simultaneously added dropwise to 60 mL of deionized water. After the addition is complete, the mixture is allowed to stand at room temperature for 12 h. After centrifugation, it is vacuum dried for 24 h to obtain CuHCF-V material with a blocky morphology of less than 500 nm in size; wherein solution A is a mixed solution of copper chloride and EDTA, and the concentration of EDTA is 6 mmol / L. -1 The concentration of copper chloride is 0.1 mol / L. -1 Solution B is 0.05 mol / L. -1 Potassium ferricyanide solution.

[0009] The present invention also provides a method for preparing the above-mentioned CuHCF-V working electrode: dissolving CuHCF-V material, conductive agent and binder in a solvent and stirring for 12 hours to obtain an electrode slurry; coating the slurry onto carbon fiber paper and vacuum drying to obtain a CuHCF-V electrode sheet.

[0010] In this invention, the conductive agent and binder can be any proportion that can be dissolved and coated by those skilled in the art.

[0011] Based on the above electrodes, this invention provides an aqueous battery, wherein the electrolyte used is a zinc ion electrolyte, a magnesium ion electrolyte, an aluminum ion electrolyte, or a calcium ion electrolyte. The counter electrode can be a graphite rod, and the reference electrode can be a saturated calomel electrode.

[0012] As is common knowledge to those skilled in the art, the electrolyte is 1 mol L. -1 ZnSO4 solution, 1 mol L - 1 MgSO4 solution, 0.5 mol / L -1 Al2(SO4)3 solution, or, 1 mol L -1CaCl2 and 1 mol L -1 A mixed solution of HCl.

[0013] The beneficial effects of this invention are as follows: This invention provides a simple one-step co-precipitation method for preparing copper hexacyanoferrate (CuHCF-V) electrode materials containing copper vacancies, and applies these materials to various aqueous ion batteries (Ca). 2+ Zn 2 + Mg 2+ Al 3+ All of them demonstrate excellent cycle life. Attached Figure Description

[0014] Figure 1 The images show the XRD patterns of CuHCF and CuHCF-V materials from Example 1. It can be seen that CuHCF-V retains the crystal structure of CuHCF.

[0015] Figure 2 These are the EPR images of CuHCF and CuHCF-V materials from Example 1. It can be seen that CuHCF-V has copper vacancies.

[0016] Figure 3 These are SEM images of CuHCF(a) and CuHCF-V(b) materials from Example 1. It can be seen that CuHCF-V has a bulk morphology with a size of less than 500 nm.

[0017] Figure 4 The graph shows the cycle performance of CuHCF and CuHCF-V materials used in zinc-ion batteries in the examples.

[0018] Figure 5 The graph shows the cycle performance of CuHCF and CuHCF-V materials used in magnesium-ion batteries in the examples.

[0019] Figure 6 The diagram shows the cycle performance of CuHCF and CuHCF-V materials used in aluminum-ion batteries in the examples.

[0020] Figure 7 The graph shows the cycle performance of CuHCF and CuHCF-V materials used in calcium-ion batteries in the examples.

[0021] Figure 8 This is a graph showing the cycle performance of CuHCF-V material with a higher loading capacity used in calcium-ion batteries. Detailed Implementation

[0022] This application introduces copper vacancies into copper hexacyanoferrite (CuHCF) in a one-step process, effectively mitigating the volume expansion caused by ion insertion / extraction and greatly enhancing the crystal structure stability. This method is suitable for various batteries (Ca...2+ Zn 2+ Mg 2+ Al 3 + It also effectively improves the initial specific capacity and cycle life of the battery.

[0023] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0024] Unless otherwise specified, the raw materials used in this invention are all conventional commercially available products; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0025] Example 1

[0026] Preparation of CuHCF-V cathode material containing Cu vacancies by coprecipitation method: ethylenediaminetetraacetic acid (EDTA) was dissolved in 120 mL of 0.1 mol L... -1 In a copper chloride solution, denoted as solution A, the concentration of EDTA is 6 mmol / L. -1 Prepare solution B, 120 mL, 0.05 mol / L. -1 Potassium ferricyanide solution. Mix solutions A and B at 2 mL / min. -1 The solution was added dropwise to 60 mL of deionized water at a constant rate. After the addition was complete, the mixture was allowed to stand at room temperature for 12 h. After centrifugation, it was vacuum dried for 24 h to obtain CuHCF-V material with a blocky morphology of less than 500 nm in size.

[0027] In contrast, the preparation method of copper hexacyanoferrite (CuHCF) electrode material without copper vacancies is as follows: 120 mL of 0.1 mol L... -1 A copper chloride solution and 120 mL of 0.05 mol / L... -1 Potassium ferricyanide solution, at 2 mL min -1 The solution was added dropwise to 60 mL of deionized water at a constant rate. After the addition was complete, the solution was allowed to stand at room temperature for 12 h. After centrifugation, the solution was vacuum dried for 24 h to obtain CuHCF material with an irregular morphology and a size of less than 300 nm.

[0028] CuHCF or CuHCF-V material, conductive agent Super P, and binder PVDF were dissolved in N-methylpyrrolidone at a mass ratio of 7:2:1 and stirred for 12 hours to obtain an electrode slurry. The slurry was coated onto rectangular carbon paper (1×1.5cm) and dried under vacuum at 60℃ for 12 hours to obtain CuHCF electrode sheets and CuHCF-V electrode sheets, respectively.

[0029] Using CuHCF electrode sheets and CuHCF-V as working electrodes, respectively, a graphite rod as the counter electrode, and a saturated calomel electrode as the reference electrode, in 10 mL of 1 mol L... -1 A three-electrode system was assembled in ZnSO4 solution. The battery cycle performance was as follows: Figure 4 As shown in the figure, the initial capacity of the CuHCF-V electrode with introduced copper vacancies, compared to the CuHCF electrode without copper vacancies, increased from 42.8 mAh g⁻¹. -1 Increased to 65.1mAh g -1 After 1000 cycles, the capacity retention rate increased from 34.5% to 65.8%, effectively improving the electrochemical performance.

[0030] Example 2

[0031] Preparation of CuHCF-V cathode material containing Cu vacancies by coprecipitation method: EDTA was dissolved in 150 mL of 0.1 mol / L... -1 In a copper chloride solution, denoted as solution A, the concentration of EDTA is 6 mmol / L. -1 Prepare solution B, 150 mL, 0.05 mol / L. -1 Potassium ferricyanide solution. Mix solutions A and B at 2 mL / min. -1 The solution was added dropwise to 30 mL of deionized water at a constant speed. After the addition was complete, the mixture was allowed to stand at room temperature for 12 h. After centrifugation, the mixture was vacuum dried for 24 h to obtain CuHCF-V material with a blocky morphology of less than 500 nm in size.

[0032] In contrast, the preparation method of copper hexacyanoferrite (CuHCF) electrode material without copper vacancies is as follows: 150 mL of 0.1 mol L... -1 A copper chloride solution and 150 mL of 0.05 mol / L... -1 Potassium ferricyanide solution, at 2 mL min -1 The solution was added dropwise to 30 mL of deionized water at a constant speed. After the addition was complete, the mixture was allowed to stand at room temperature for 12 h. After centrifugation, it was vacuum dried for 24 h to obtain CuHCF material with an irregular morphology and a size of less than 300 nm.

[0033] CuHCF or CuHCF-V material, conductive agent Super P, and binder PVDF were dissolved in N-methylpyrrolidone at a mass ratio of 7:2:1 and stirred for 12 hours to obtain an electrode slurry. The slurry was coated onto rectangular carbon paper (1×1.5cm) and dried under vacuum at 60℃ for 12 hours to obtain CuHCF electrode sheets and CuHCF-V electrode sheets, respectively.

[0034] Using CuHCF electrode sheets and CuHCF-V as working electrodes, respectively, a graphite rod as the counter electrode, and a saturated calomel electrode as the reference electrode, in 10 mL of 1 mol L... -1 A three-electrode system was assembled in MgSO4 solution. The battery cycle performance was as follows: Figure 5 As shown in the figure, the initial capacity of the CuHCF-V electrode with introduced copper vacancies, compared to the CuHCF electrode without copper vacancies, increased from 42.2 mAh g⁻¹. -1 Increased to 54.4mAh g -1 The capacity retention rate increased from 38.5% after 1049 cycles to 70.8% after 26210 cycles, effectively improving the electrochemical performance.

[0035] Example 3

[0036] Preparation of CuHCF-V cathode material containing Cu vacancies by coprecipitation method: 3 mmol L -1 Ethylenediaminetetraacetic acid (EDTA) dissolved in 120 mL of 0.05 mol / L solution -1 In a copper chloride solution, let's call it solution A. Prepare solution B: 120 mL of 0.025 mol / L... -1 Potassium ferricyanide solution. Mix solutions A and B at 2 mL / min. -1 The solution was added dropwise to 60 mL of deionized water at a constant rate. After the addition was complete, the mixture was allowed to stand at room temperature for 12 h. After centrifugation, it was vacuum dried for 24 h to obtain CuHCF-V material with a blocky morphology of less than 500 nm in size.

[0037] In contrast, a method for preparing copper hexacyanoferrite (CuHCF) electrode material without copper vacancies was described. 120 mL of 0.05 mol / L... -1 A copper chloride solution and 120 mL of 0.025 mol / L... -1 Potassium ferricyanide solution, at 2 mL min -1 The solution was added dropwise to 60 mL of deionized water at a constant rate. After the addition was complete, the solution was allowed to stand at room temperature for 12 h. After centrifugation, the solution was vacuum dried for 24 h to obtain CuHCF material with an irregular morphology and a size of less than 300 nm.

[0038] CuHCF or CuHCF-V material, conductive agent Super P, and binder PVDF were dissolved in N-methylpyrrolidone at a mass ratio of 7:2:1 and stirred for 12 hours to obtain an electrode slurry. The slurry was coated onto rectangular carbon paper (1×1.5cm) and dried under vacuum at 60℃ for 12 hours to obtain CuHCF electrode sheets and CuHCF-V electrode sheets, respectively.

[0039] Using CuHCF electrode sheets and CuHCF-V as working electrodes, respectively, a graphite rod as the counter electrode, and a saturated calomel electrode as the reference electrode, in 10 mL of 0.5 mol / L... -1 A three-electrode system was assembled in Al2(SO4)3 solution. The battery cycle performance was as follows: Figure 6 As shown in the figure, the initial capacity of the CuHCF-V electrode with introduced copper vacancies, compared to the CuHCF electrode without copper vacancies, increased from 49.4 mAh g⁻¹. -1 Increased to 64.5mAh g -1 After 1000 cycles, the capacity retention rate increased from 40.7% to 59.8%, effectively improving the electrochemical performance.

[0040] Example 4

[0041] Preparation of CuHCF-V cathode material containing Cu vacancies by coprecipitation method: 6 mmol L -1 EDTA is dissolved in 120 mL of 0.1 mol / L solution. -1 In a copper chloride solution, let's call it solution A. Prepare solution B: 120 mL of 0.05 mol / L... -1 Potassium ferricyanide solution. Mix solutions A and B at 2 mL / min. -1 The solution was added dropwise to 60 mL of deionized water at a constant rate. After the addition was complete, the mixture was allowed to stand at room temperature for 12 h. After centrifugation, it was vacuum dried for 24 h to obtain CuHCF-V material with a blocky morphology of less than 500 nm in size.

[0042] In contrast, a method for preparing copper hexacyanoferrite (CuHCF) electrode material without copper vacancies was described. 120 mL of 0.1 mol L... -1 A copper chloride solution and 120 mL of 0.05 mol / L... -1 Potassium ferricyanide solution, at 2 mL min -1 The solution was added dropwise to 60 mL of deionized water at a constant rate. After the addition was complete, the solution was allowed to stand at room temperature for 12 h. After centrifugation, the solution was vacuum dried for 24 h to obtain CuHCF material with an irregular morphology and a size of less than 300 nm.

[0043] CuHCF or CuHCF-V material, conductive agent Super P, and binder PVDF were dissolved in N-methylpyrrolidone at a mass ratio of 7:2:1 and stirred for 12 hours to obtain an electrode slurry. The slurry was coated onto rectangular carbon paper (1×1.5cm) and dried under vacuum at 60℃ for 12 hours to obtain CuHCF electrode sheets and CuHCF-V electrode sheets, respectively.

[0044] Using CuHCF electrode sheets and CuHCF-V as working electrodes, respectively, a graphite rod as the counter electrode, and a saturated calomel electrode as the reference electrode, in 10 mL of 1 mol L... -1 CaCl2 and 1 mol L -1 A three-electrode system is assembled in a mixed solution of HCl. The battery cycle performance is as follows: Figure 7 As shown in the figure, the initial capacity of the CuHCF-V electrode with introduced copper vacancies, compared to the CuHCF electrode without copper vacancies, increased from 60.4 mAh g⁻¹. -1 Increased to 64.4mAh g -1 After 10,000 cycles, the capacity retention increased from 58.2% to 106.9%. The increase in capacity is due to the dissolution of Cu and Fe in the early stage of cycling and their stability in the later stage of cycling, which effectively improved the electrochemical performance.

[0045] Example 5

[0046] CuHCF-V cathode material containing Cu vacancies was prepared by co-precipitation method, using 10 mmol L -1 Ethylenediaminetetraacetic acid (EDTA) dissolved in 120 mL of 0.16 mol / L solution -1 In a copper chloride solution, let's call it solution A. Prepare solution B: 120 mL of 0.083 mol / L... -1 Potassium ferricyanide solution. Mix solutions A and B at 2 mL / min. -1 The solution was added dropwise to 60 mL of deionized water at a constant rate. After the addition was complete, the mixture was allowed to stand at room temperature for 12 h. After centrifugation, it was vacuum dried for 24 h to obtain CuHCF-V material with a blocky morphology of less than 500 nm in size.

[0047] CuHCF-V material, conductive agent Super P, and binder PVDF were dissolved in N-methylpyrrolidone at a mass ratio of 7:2:1 and stirred for 12 h to obtain an electrode slurry. The slurry was coated onto rectangular carbon paper (1×1.5 cm) and dried under vacuum at 60 °C for 12 h to obtain CuHCF electrode sheets and CuHCF-V electrode sheets, respectively.

[0048] CuHCF-V was used as the working electrode, and the loading was increased to ~11 mg cm⁻¹. -2 A graphite rod is used as the counter electrode, and a saturated calomel electrode is used as the reference electrode. The reaction mixture is in 10 mL of 1 mol L⁻¹ solution. -1 CaCl2 and 1 mol L -1 A three-electrode system is assembled in a mixed solution of HCl. The battery cycle performance is as follows: Figure 8As shown in the figure, the CuHCF-V electrode with introduced copper vacancies still maintains a capacity retention of 93.7% after 500,000 cycles. The increase in capacity in the early stage is due to the dissolution of Cu and Fe in the early stage of cycling, which remains stable in the later stage of cycling, effectively improving the electrochemical performance.

[0049] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing a copper hexacyanoferrite CuHCF-V electrode material containing copper vacancies, characterized in that, EDTA (ethylenediaminetetraacetic acid) was dissolved in copper chloride solution to form solution A; potassium ferricyanide was dissolved in water to form solution B; solutions A and B were simultaneously added dropwise to deionized water; after the addition was complete, the solution was allowed to stand at room temperature for 12 h, centrifuged, and then vacuum dried to obtain CuHCF-V material; wherein copper chloride, potassium ferricyanide, and EDTA were prepared in a molar ratio of iron, copper, and EDTA of 50:100:6; the concentration of EDTA in solution A was 3-10 mmol / L. -1 .

2. The preparation method according to claim 1, characterized in that, In solution A, the concentration of ethylenediaminetetraacetic acid (EDTA) is 6 mmol / L. -1 .

3. A CuHCF-V electrode, characterized in that, It includes a substrate and an electrode layer coated on the substrate, wherein the electrode layer comprises the CuHCF-V material prepared by the method of claim 1.

4. An aqueous battery, characterized in that, The electrode described in claim 3 is used.

5. The aqueous battery according to claim 4, characterized in that, The electrolyte used is zinc ion electrolyte, magnesium ion electrolyte, aluminum ion electrolyte or calcium ion electrolyte.

6. The aqueous battery according to claim 5, characterized in that, The electrolyte is 1 mol L. -1 ZnSO4 solution, 1 mol L -1 MgSO4 solution, 0.5 mol / L -1 Al2(SO4)3 solution, or, 1 mol L -1 CaCl2 and 1 mol L -1 A mixed solution of HCl.

7. The aqueous battery according to claim 5, characterized in that, The counter electrode is a graphite rod, and the reference electrode is a saturated calomel electrode.

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