Alkaline earth metal ion-doped copper fluoride, preparation method and application thereof

Abstract

The present invention discloses an alkaline earth metal ion-doped copper fluoride, and its preparation method and application. The preparation method of the alkaline earth metal ion-doped copper fluoride comprises the following steps: preparing a copper salt solution and an alkaline oxide solution respectively; mixing the copper salt solution and the alkaline oxide solution, stirring and reacting at 30-70°C, and obtaining a precursor mixture after the reaction is completed; filtering and washing the precursor mixture and drying it to obtain a dry precursor sample, and then uniformly mixing it with a fluorine source and heat-treating it at 240-320°C under a protective atmosphere. After the heat treatment is completed, the alkaline earth metal ion-doped copper fluoride is obtained. The present invention reduces the use of water in the preparation process, thereby reducing wastewater discharge; at the same time, the present invention improves the preparation efficiency by simplifying the process, and the porous copper fluoride obtained is doped with alkaline earth metal ions, and the band structure is regulated and the electrochemical activity is improved.

Description

Technical Field

[0001] The present invention belongs to the field of electrode materials, and in particular relates to alkaline earth metal ion-doped copper fluoride, a preparation method thereof, and applications thereof. Background Art

[0002] The development of new energy vehicles is driving a growing demand for high-energy-density lithium-ion batteries. However, existing commercial lithium-ion batteries are limited by the specific capacity of their intercalation compound cathode materials (such as LiCoO2, LiMn2O4, and LiFePO4), making their energy density increasingly inadequate to meet the demands of new energy vehicles. Consequently, conversion materials with higher specific capacities have attracted significant attention in recent years. Among these materials, transition metal fluorides, due to their high theoretical potential and theoretical specific capacity, exhibit high theoretical energy density and are considered promising candidates to replace existing cathode materials.

[0003] As one of the transition metal fluorides, CuF2 is considered to have good development potential due to its high theoretical potential (3.55 V), high theoretical specific capacity (528 mAh / g) and high energy density (1874 Wh / Kg). However, due to the high ionic bond strength of Cu-F, its electrical conductivity is low, which seriously affects the electrochemical activity of CuF2. At present, there are several main measures to improve the electrochemical performance of copper fluoride: composite with carbon materials, but this method requires the introduction of more inactive substances, which may affect the overall energy density; and doping of copper fluoride can affect its energy band structure and improve electrochemical performance, but the current doping system often leads to a decrease in the voltage of copper fluoride, thereby affecting its energy density. Recent studies have found that constructing a porous structure of CuF2 can increase the specific surface area of ​​the material, shorten the electron transport distance, and accelerate Li + Diffusion can significantly improve the electrochemical activity of copper fluoride. For example, Hu et al. reported that porous CuF2 prepared by co-precipitation exhibited excellent electrochemical activity (reference 10.1007 / s10853-023-08668-0). However, this method uses NaOH as a precipitant to synthesize the precursor, which makes process control more difficult, has poor stability, and is prone to the formation of impurities, resulting in poor electrochemical performance of the final product. In addition, this method requires the introduction of a large amount of water during the synthesis process, which not only increases the environmental burden but also is not conducive to large-scale preparation. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide an alkaline earth metal ion doped copper fluoride and its preparation method and application. Compared with the existing method for preparing porous CuF2, the present invention uses MgO, CaO, SrO and BaO as alkaline oxides, whose aqueous solutions are alkaline and can stably and continuously provide OH for the precursor precipitation reaction. -, and a basic copper acetate precipitate is generated. This preparation process is simple to control, significantly reduces water usage, and is environmentally friendly. Furthermore, the alkaline earth metal oxide in this method acts as both a precipitant and a dopant, introducing the alkaline earth metal into CuF2 to modulate its band structure and improve its electrochemical activity.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A method for preparing alkaline earth metal ion-doped copper fluoride comprises the following steps:

[0007] (1) Prepare copper salt solution and alkaline oxide solution respectively;

[0008] (2) Mixing the copper salt solution and the alkaline oxide solution, stirring and reacting at 30-70°C, and obtaining a precursor mixture after the reaction is completed;

[0009] (3) The precursor mixture is filtered, washed, and then dried to obtain a dry precursor sample, which is then uniformly mixed with a fluorine source and heat-treated at 240-320°C in a protective atmosphere. After the heat treatment is completed, copper fluoride doped with alkaline earth metal ions is obtained.

[0010] Preferably, in step (1), the copper salt solution is prepared as follows: adding the copper salt to water at 30-70° C., stirring and fully dissolving the copper salt.

[0011] Preferably, the copper salt is copper acetate.

[0012] Preferably, the concentration of the copper salt solution is 0.05-1 mol / L.

[0013] Preferably, in step (1), the alkaline oxide solution is prepared as follows: adding the alkaline oxide to water at 30-70° C., stirring and fully dispersing the water.

[0014] Preferably, the basic oxide is at least one of MgO, CaO, SrO and BaO.

[0015] Preferably, the concentration of metal ions in the alkaline oxide solution is 0.03-0.75 mol / L.

[0016] Preferably, in step (2), the mass ratio of the copper salt in the copper salt solution to the alkaline oxide in the alkaline oxide solution is 0.9-19.0:0.1-8.0.

[0017] Preferably, in step (2), the stirring time is 30 to 120 minutes.

[0018] Preferably, in step (3), the dried precursor sample is mixed with the fluorine source and fully ground, and then heat-treated.

[0019] Preferably, in step (3), the mass ratio of the fluorine source to the dried precursor sample is 2-10:1.

[0020] Preferably, in step (3), the fluorine source is at least one of ammonium fluoride and ammonium bifluoride.

[0021] Preferably, in step (3), the heat treatment time is 2 to 6 hours.

[0022] Preferably, in step (3), the protective atmosphere is nitrogen or an inert gas.

[0023] Preferably, the inert gas is argon.

[0024] The alkaline earth metal ion-doped copper fluoride is prepared by the above-mentioned preparation method of alkaline earth metal ion-doped copper fluoride.

[0025] Application of the above-mentioned alkaline earth metal ion-doped copper fluoride as lithium ion positive electrode material.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The present invention does not introduce much water during the preparation process, which not only reduces dependence on water resources, but also reduces the wastewater discharge that may be generated during the synthesis process, thereby reducing the burden on the environment.

[0028] (2) The process of the present invention is streamlined and the preparation efficiency is high. The prepared copper fluoride doped with alkaline earth metal ions has a porous structure. The doping of alkaline earth metal ions can regulate its energy band structure and improve the electrochemical activity of CuF2. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is the XRD diffraction pattern of the alkaline earth metal ion-doped copper fluoride prepared in Example 1, wherein the right image is a partial enlarged view of the left image.

[0030] Figure 2 This is the first cycle charge and discharge curve of the alkaline earth metal ion-doped copper fluoride prepared in Example 1.

[0031] Figure 3 This is the SEM image of the alkaline earth metal ion-doped copper fluoride prepared in Example 1. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0033] Example 1

[0034] A method for preparing copper fluoride doped with alkaline earth metal ions, comprising the following steps:

[0035] (1) Weigh 9.07 g of copper acetate and add it to 100 mL of deionized water. Heat and stir at 50°C to fully dissolve it to form a 0.5 mol / L copper acetate solution.

[0036] (2) Weigh 5.4 g of BaO and add it to 100 mL of deionized water. Heat and stir at 50 °C to disperse it evenly to form a 0.35 mol / L oxide solution.

[0037] (3) The copper acetate solution of step (1) was slowly added dropwise to the oxide solution of step (2), and the mixture was stirred and reacted at a water bath temperature of 50° C. for 60 minutes to obtain a precursor mixture.

[0038] (4) The precursor mixture is filtered, washed, and dried to obtain a dry precursor (containing basic copper acetate).

[0039] (5) The dried precursor and ammonium fluoride were mixed and ground in a mass ratio of 1:2 to obtain a mixed powder after uniform grinding. The mixed powder was placed in a tubular furnace filled with argon and heat-treated at 290°C for 4 hours. After the heat treatment, copper fluoride doped with alkaline earth metal ions was obtained.

[0040] Example 2

[0041] A method for preparing copper fluoride doped with alkaline earth metal ions, comprising the following steps:

[0042] (1) Weigh 18 g of copper acetate and add it to 100 mL of deionized water. Heat and stir at 70°C to fully dissolve it to form a 1 mol / L copper acetate solution.

[0043] (2) Weigh 2.24 g of CaO and 5.37 g of BaO and add them to 100 mL of deionized water. Heat and stir at 70 °C to disperse them evenly to form a 0.75 mol / L oxide solution.

[0044] (3) The copper acetate solution of step (1) was slowly added dropwise to the oxide solution of step (2), and the mixture was stirred and reacted at a water bath temperature of 70° C. for 120 minutes to obtain a precursor mixture.

[0045] (4) The precursor mixture is filtered, washed, and dried to obtain a dry precursor (containing basic copper acetate).

[0046] (5) The dried precursor and ammonium fluoride were mixed and ground in a mass ratio of 1:10 to obtain a mixed powder after uniform grinding. The mixed powder was placed in a tubular furnace filled with argon and heat-treated at 240°C for 6 hours. After the heat treatment, copper fluoride doped with alkaline earth metal ions was obtained.

[0047] Example 3

[0048] A method for preparing copper fluoride doped with alkaline earth metal ions, comprising the following steps:

[0049] (1) Weigh 12.7 g of copper acetate and add it to 100 mL of deionized water. Heat and stir at 60°C to fully dissolve it to form a 0.7 mol / L copper acetate solution.

[0050] (2) Weigh 5.2 g of SrO and add it to 100 mL of deionized water. Heat and stir at 60 °C to disperse it evenly to form a 0.5 mol / L oxide solution.

[0051] (3) The copper acetate solution of step (1) was slowly added dropwise to the oxide solution of step (2), and the mixture was stirred and reacted at a water bath temperature of 60° C. for 60 minutes to obtain a precursor mixture.

[0052] (4) The precursor mixture is filtered, washed, and dried to obtain a dry precursor (containing basic copper acetate).

[0053] (5) The dried precursor and ammonium fluoride were mixed and ground in a mass ratio of 1:6. After grinding evenly, a mixed powder was obtained. The mixed powder was placed in a tubular furnace filled with argon and heat-treated at 300°C for 2 hours. After the heat treatment, copper fluoride doped with alkaline earth metal ions was obtained.

[0054] Example 4

[0055] A method for preparing copper fluoride doped with alkaline earth metal ions, comprising the following steps:

[0056] (1) Weigh 12.7 g of copper acetate and add it to 100 mL of deionized water. Heat and stir at 50°C to fully dissolve it to form a 0.7 mol / L copper acetate solution.

[0057] (2) Weigh 7.6 g of BaO and add it to 100 mL of deionized water. Heat and stir at 50 °C to disperse it evenly to form a 0.5 mol / L oxide solution.

[0058] (3) The copper acetate solution of step (1) was slowly added dropwise to the oxide solution of step (2), and the mixture was stirred and reacted at a water bath temperature of 50° C. for 90 minutes to obtain a precursor mixture.

[0059] (4) The precursor mixture is filtered, washed, and dried to obtain a dry precursor (containing basic copper acetate).

[0060] (5) The dried precursor and ammonium fluoride were mixed and ground in a mass ratio of 1:5. After grinding evenly, a mixed powder was obtained. The mixed powder was placed in a tubular furnace filled with argon and heat-treated at 280°C for 5 hours. After the heat treatment, copper fluoride doped with alkaline earth metal ions was obtained.

[0061] Example 5

[0062] A method for preparing copper fluoride doped with alkaline earth metal ions, comprising the following steps:

[0063] (1) Weigh 0.91 g of copper acetate and add it to 100 mL of deionized water. Heat and stir at 30°C to fully dissolve it to form a 0.05 mol / L copper acetate solution.

[0064] (2) Weigh 0.12 g of MgO and add it to 100 mL of deionized water. Heat and stir at 30°C to disperse it evenly to form a 0.03 mol / L oxide solution.

[0065] (3) Slowly dropwise add the copper acetate solution described in step (1) to the oxide solution described in step (2), and stir the reaction at a water bath temperature of 30° C. for 60 minutes to obtain a precursor mixture.

[0066] (4) The precursor mixture is filtered, washed, and dried to obtain a dry precursor (containing basic copper acetate).

[0067] (5) The dried precursor and ammonium fluoride were mixed and ground in a mass ratio of 1:2 to obtain a mixed powder after uniform grinding. The mixed powder was placed in a tubular furnace filled with argon and heat-treated at 300°C for 3 hours. After the heat treatment, copper fluoride doped with alkaline earth metal ions was obtained.

[0068] Example 6

[0069] A method for preparing copper fluoride doped with alkaline earth metal ions, comprising the following steps:

[0070] (1) Weigh 14.52 g of copper acetate and add it to 100 mL of deionized water. Heat and stir at 70°C to fully dissolve it to form a 0.8 mol / L copper acetate solution.

[0071] (2) Weigh 0.8 g of MgO, 1.1 g of CaO, and 3.1 g of BaO and add them to 100 mL of deionized water. Heat and stir at 70 °C to disperse them evenly to form a 0.6 mol / L oxide solution.

[0072] (3) The copper acetate solution of step (1) was slowly added dropwise to the oxide solution of step (2), and the mixture was stirred and reacted at a water bath temperature of 70° C. for 120 minutes to obtain a precursor mixture.

[0073] (4) The precursor mixture is filtered, washed, and dried to obtain a dry precursor (containing basic copper acetate).

[0074] (5) The dried precursor and ammonium fluoride were mixed and ground in a mass ratio of 1:7. After grinding evenly, a mixed powder was obtained. The mixed powder was placed in a tubular furnace filled with argon and heat-treated at 250°C for 4 hours. After the heat treatment, copper fluoride doped with alkaline earth metal ions was obtained.

[0075] The positive electrode was prepared using the alkaline earth metal ion-doped copper fluoride prepared in the example as the positive electrode active material, polyvinylidene fluoride (PVDF) and carbon black as raw materials. The alkaline earth metal ion-doped copper fluoride (CFM) accounted for 70 wt% of the raw materials, polyvinylidene fluoride (PVDF) accounted for 20 wt%, and carbon black accounted for 10 wt%. The slurry composed of these three raw materials was cast onto a 10 mm thick Al foil sheet to prepare the electrode. The prepared electrode was then dried in a vacuum oven. R2032 button cells were assembled using a LiTFSI / TMS (1:10) sulfolane electrolyte, a lithium metal sheet anode, and a Celgard 2500 separator to characterize their electrochemical performance. The cells were then subjected to charge and discharge tests at a voltage of 1.5-4.2 V and a current density of 0.1 C.

[0076] Figure 1 This is the XRD diffraction pattern of the alkaline earth metal ion-doped copper fluoride prepared in Example 1, wherein the right figure is a partial enlarged view of the left figure. Figure 1 We can see that the primary diffraction peaks in the resulting XRD diffraction pattern are consistent with those of the copper fluoride standard card (JCPDS card no. 70-1936). A zoomed-in image reveals that the diffraction peak at approximately 2 Thete = 27.5° shifts toward lower angles, demonstrating that barium ions with larger ionic radius have been successfully incorporated into the CuF2 cathode material.

[0077] Figure 2 This is the first cycle charge and discharge curve of the alkaline earth metal ion doped copper fluoride prepared in Example 1. Figure 2 We can see that the first-cycle discharge voltage platform of Ba-doped copper fluoride reaches above 2.8V, and the first-cycle discharge capacity reaches 497.77mAh / g.

[0078] Figure 3 This is the SEM image of the alkaline earth metal ion-doped copper fluoride prepared in Example 1. Figure 3We can see that the prepared alkaline earth metal ion-doped copper fluoride is composed of loose and porous blocks, and the size is mostly concentrated in the range of 2~4μm.

[0079] The electrochemical performance statistics of the batteries prepared by using the alkaline earth metal ion-doped copper fluoride described in Examples 1 to 6 as the positive electrode material are shown in Table 1.

[0080] Table 1 Electrochemical performance of batteries corresponding to Examples 1 to 6

[0081]

[0082] As shown in Table 1, we can know that the battery prepared by using the alkaline earth metal ion-doped copper fluoride prepared in the present invention as the positive electrode material has good electrochemical performance.

[0083] The specific embodiments of the present invention described above do not limit the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A method for preparing copper fluoride doped with alkaline earth metal ions, characterized in that: The steps include: (1) Prepare copper salt solution and alkaline oxide solution respectively; (2) mixing the copper salt solution and the alkaline oxide solution, and stirring them at 30-70° C. to react, and obtaining a precursor mixture after the reaction is completed; (3) The precursor mixture is filtered, washed, and then dried to obtain a dry precursor sample, which is then uniformly mixed with a fluorine source and heat-treated at 240-320° C. in a protective atmosphere to obtain the alkaline earth metal ion-doped copper fluoride.

2. The method for preparing alkaline earth metal ion-doped copper fluoride according to claim 1, characterized in that: The copper salt solution in step (1) is prepared as follows: adding copper salt to water at 30-70°C, stirring and fully dissolving the copper salt; The alkaline oxide solution in step (1) is prepared as follows: adding the alkaline oxide to water at 30-70° C., stirring and fully dispersing the water.

3. The method for preparing alkaline earth metal ion-doped copper fluoride according to claim 2, characterized in that: The copper salt is copper acetate; The basic oxide is at least one of MgO, CaO, SrO and BaO.

4. The method for preparing alkaline earth metal ion-doped copper fluoride according to claim 3, characterized in that: The concentration of the copper salt solution is 0.05~1mol / L; In the alkaline oxide solution, the concentration of metal ions is 0.03-0.75 mol / L.

5. The method for preparing alkaline earth metal ion-doped copper fluoride according to any one of claims 2 to 4, characterized in that: The mass ratio of the copper salt in the copper salt solution to the alkaline oxide in the alkaline oxide solution in step (2) is 0.9-19.0:0.1-8.0; The stirring time in step (2) is 30 to 120 minutes.

6. The method for preparing alkaline earth metal ion-doped copper fluoride according to claim 5, characterized in that: In step (3), the dried precursor sample is mixed with a fluorine source and fully ground, and then heat-treated.

7. The method for preparing alkaline earth metal ion-doped copper fluoride according to claim 6, characterized in that: The mass ratio of the fluorine source to the dried precursor sample in step (3) is 2 to 10:1; The fluorine source in step (3) is at least one of ammonium fluoride and ammonium bifluoride.

8. The method for preparing alkaline earth metal ion-doped copper fluoride according to claim 1, characterized in that: The heat treatment time in step (3) is 2 to 6 hours; The protective atmosphere in step (3) is nitrogen or an inert gas.

9. Alkaline earth metal ion-doped copper fluoride prepared by the method for preparing alkaline earth metal ion-doped copper fluoride according to any one of claims 1 to 8.

10. Use of the alkaline earth metal ion-doped copper fluoride according to claim 9 as a lithium ion positive electrode material.

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