Preparation method and application of ternary prussian blue derivative nanocage core-shell electrode material

Abstract

The application relates to a preparation method and application of a ternary prussian blue derivative nanocage core-shell electrode material, and relates to a preparation method and application of an electrode material. The application aims to solve the problems of poor electrochemical performance and low cycle life of existing supercapacitors. The method comprises the following steps: I, preparing nickel-cobalt-iron prussian blue; II, preparing a core-shell electrode material; and the ternary prussian blue derivative nanocage core-shell electrode material is used as a supercapacitor. The electrochemical performance of the obtained ternary prussian blue derivative nanocage core-shell electrode material is tested, and experiments show that the electrode material has high capacitive performance; when the current density is 1 A / g, the specific capacity of the material in 1 mol / L KOH solution reaches 1644.4 F / g; after 6000 single electrode cycles, there is still 97.27% of the initial capacitance value, which indicates that the supercapacitor core-shell electrode material provided by the application has high service life.

Description

Technical Field

[0001] This invention relates to a method for preparing an electrode material and its application. Background Technology

[0002] Electrochemical energy storage devices such as fuel cells, lithium-ion batteries, and supercapacitors show great promise in utilizing new energy sources such as solar and wind power. Among them, supercapacitors, with their advantages of long cycle life, high power density, wide operating temperature range, and good safety, are widely used in portable electronic devices, backup power storage, and electric vehicles. The main components of a supercapacitor are: positive electrode, negative electrode, electrolyte, separator, and outer packaging. Among these, the electrode materials play a decisive role in the energy storage characteristics of supercapacitors, making the development of high-performance electrode materials particularly important.

[0003] Among the many electrode materials for supercapacitors, those with Faraday redox properties, such as transition metal oxides, hydroxides, and sulfides, exhibit high theoretical capacitance values. Nickel-based and cobalt-based sulfide nanomaterials, such as CoS2 and NiS2, possess rich redox chemical states and better conductivity. Furthermore, numerous reports have indicated that multi-metal sulfide electrodes have higher charge storage capacity compared to single-metal sulfide electrodes. Notably, the microstructure of the material can not only increase the active surface area but also release stress generated during electrochemical processes, thereby improving the specific capacitance and structural stability, further optimizing the electrochemical performance and cycle life of supercapacitors. Therefore, designing multi-metal sulfide electrodes with unique morphologies is more beneficial for the development of supercapacitors. Summary of the Invention

[0004] The purpose of this invention is to solve the problems of poor electrochemical performance and low cycle life of existing supercapacitors, and to provide a ternary Prussian blue derived nanocage core-shell electrode material, its preparation method, and its application.

[0005] A ternary Prussian blue-derived nanocage core-shell electrode material is formed by using ternary Prussian blue as the shell and derived metal sulfide nanoparticles as the core to form a nanocage core-shell cube, wherein the thickness of the shell is 15-25 nm and the diameter of the nanocage core-shell cube is 150-350 nm.

[0006] A method for preparing a ternary Prussian blue-derived nanocage core-shell electrode material is specifically carried out according to the following steps:

[0007] I. Preparation of Nickel-Cobalt-Iron Prussian Blue:

[0008] ① Dissolve Ni(CH3COO)2·4H2O, Co(CH3COO)2·4H2O and Na3C6H5O7·2H2O in deionized water to obtain solution A;

[0009] ② Dissolve K3[Fe(CN)6] in deionized water to obtain solution B;

[0010] ③ Add solution B dropwise to solution A and stir continuously to obtain mixed solution I; age mixed solution I at room temperature to obtain a precipitate; wash the precipitate and then dry it to obtain nickel-cobalt-iron Prussian blue;

[0011] II. Preparation of core-shell electrode materials:

[0012] ① Dissolve thioacetamide in anhydrous ethanol, then add nickel-cobalt-iron Prussian blue, ultrasonically disperse, and then stir.

[0013] Mixed solution II was obtained;

[0014] ② Transfer the mixed solution II to a high-pressure reactor, seal it, and place it in a high-temperature oven. Keep it at 150℃~170℃ and let it cool naturally to room temperature to obtain the reaction product. Wash the reaction product and then vacuum dry it to obtain the ternary Prussian blue derived nanocage core-shell electrode material.

[0015] A ternary Prussian blue-derived nanocage core-shell electrode material is used as a supercapacitor.

[0016] The principle of this invention:

[0017] This invention provides a method for preparing a core-shell electrode material of multi-metal sulfides grown within nickel-cobalt-iron Prussian blue nanocages. The core-shell electrode material (NCFS@PBA) composed of nickel-cobalt-iron Prussian blue (NiCoFePBA) and its internally derived multi-metal sulfides (NCFS) exhibits a unique microstructure and, when applied in supercapacitors, demonstrates excellent specific capacitance and cycling performance. This invention obtains a stable cubic core-shell electrode material (NCFS@PBA) with internally aggregated nanoparticles through room temperature co-precipitation and solvothermal synthesis. In this design, NiCoFePBA serves as a precursor, fully utilizing its high stability and porosity. The PBA core-shell electrode material offers numerous advantages, providing a variety of transition metals for the derived sulfides and effectively preventing the oxidation of internal sulfides. The multi-metal sulfide (NCFS) nanoparticles derived within the PBA are composed of CoS2 and (Ni,Fe)S2, with fully exposed active sites, facilitating ion diffusion into the material and providing high specific capacity. The PBA shell and NCFS core of the core-shell electrode material exhibit a strong synergistic effect, resulting in excellent specific capacity and long cycle life as an electrode for supercapacitors. This design approach provides new ideas for the design of other electrode materials, such as cathode materials for sodium-ion batteries, and can be further extended to applications in other energy storage devices.

[0018] Advantages of this invention:

[0019] I. Prussian blue analogues (PBAs) are metal-organic framework compounds with a rigid framework structure and multiple transition metal elements. Their abundant porous structure provides sufficient channels for electrolyte ion diffusion. Therefore, PBAs are ideal precursors for constructing core-shell structured multi-metal sulfide electrode materials. Through rational structural design, a composite material can be prepared that retains the porous structure of PBA while possessing the high specific capacitance of multi-metal sulfides, thereby achieving high-performance, high-energy-density supercapacitors. This represents a very promising electrode design solution.

[0020] II. The electrochemical performance of the obtained ternary Prussian blue-derived nanocage core-shell electrode material (NCFS@PBA) was tested in this invention. Cyclic voltammetry and constant current charge-discharge tests showed that the electrode material has high capacitance performance. When the current density is 1 A / g, the specific capacitance of the material in 1 mol / L KOH solution reaches 1644.4 F / g. After 6000 cycles of a single electrode, 97.27% of the initial capacitance value is still retained, which indicates that the supercapacitor core-shell electrode material provided by this invention has a long service life. Attached Figure Description

[0021] Figure 1The images are SEM images. In the image, (a) is the nickel-cobalt-iron Prussian blue prepared in step one of Example 1, and (b) is the ternary Prussian blue-derived nanocage core-shell electrode material prepared in step two of Example 1.

[0022] Figure 2 Transmission electron microscopy (TEM) images at different magnifications of the ternary Prussian blue-derived nanocage core-shell electrode material prepared in step two of Example 1;

[0023] Figure 3 The X-ray diffraction pattern of the ternary Prussian blue-derived nanocage core-shell electrode material prepared in step two of Example 1;

[0024] Figure 4 Cyclic voltammetry curves of the ternary Prussian blue-derived nanocage core-shell electrode material prepared in step two of Example 1 at different scan rates;

[0025] Figure 5 The constant current charge-discharge curves of the ternary Prussian blue-derived nanocage core-shell electrode material prepared in step two of Example 1 at different current densities are shown.

[0026] Figure 6 The graph shows the cycling performance of the ternary Prussian blue-derived nanocage core-shell electrode material prepared in step two of Example 1 at a current density of 15 A / g.

[0027] Figure 7 The constant current charge-discharge curves of the nickel-cobalt-iron Prussian blue prepared in step one of Example 1 and the ternary Prussian blue-derived nanocage core-shell electrode materials prepared in step two of Example 1 are shown at a current density of 1 A / g. Detailed Implementation

[0028] The following embodiments further illustrate the content of the present invention, but should not be construed as limiting the present invention. Any modifications and substitutions made to the methods, steps, or conditions of the present invention without departing from the essence of the invention are within the scope of the present invention.

[0029] Specific Implementation Method 1: In this implementation method, a ternary Prussian blue-derived nanocage core-shell electrode material is formed by using ternary Prussian blue as the shell and derived metal sulfide nanoparticles as the core to form a nanocage core-shell cube, wherein the thickness of the shell is 15-25 nm and the diameter of the nanocage core-shell cube is 150-350 nm.

[0030] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that it involves a method for preparing a ternary Prussian blue-derived nanocage core-shell electrode material, specifically completed according to the following steps:

[0031] I. Preparation of Nickel-Cobalt-Iron Prussian Blue:

[0032] ① Dissolve Ni(CH3COO)2·4H2O, Co(CH3COO)2·4H2O and Na3C6H5O7·2H2O in deionized water to obtain solution A;

[0033] ② Dissolve K3[Fe(CN)6] in deionized water to obtain solution B;

[0034] ③ Add solution B dropwise to solution A and stir continuously to obtain mixed solution I; age mixed solution I at room temperature to obtain a precipitate; wash the precipitate and then dry it to obtain nickel-cobalt-iron Prussian blue;

[0035] II. Preparation of core-shell electrode materials:

[0036] ① Dissolve thioacetamide in anhydrous ethanol, then add nickel-cobalt-iron Prussian blue, ultrasonically disperse, and then stir.

[0037] Mixed solution II was obtained;

[0038] ② Transfer the mixed solution II to a high-pressure reactor, seal it, and place it in a high-temperature oven. Keep it at 150℃~170℃ and allow it to cool naturally to room temperature to obtain the reaction product. Wash the reaction product and then vacuum dry it to obtain the ternary Prussian blue-derived nanocage core-shell electrode material. Other steps are the same as in Specific Implementation Method 1.

[0039] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that: the molar ratio of Ni(CH3COO)2·4H2O to the volume of deionized water in step one ① is (1mmol~3mmol):(60mL~100mL); the molar ratio of Ni(CH3COO)2·4H2O, Co(CH3COO)2·4H2O, and Na3C6H5O7·2H2O in step one ① is 2:1:(2~4). The other steps are the same as in Specific Implementation Method One or Two.

[0040] Specific Implementation Method Four: The difference between this implementation method and Specific Implementation Methods One to Three is that the molar ratio of K3[Fe(CN)6] in step one ② to Ni(CH3COO)2·4H2O in step one ① is (1-2):2. The other steps are the same as in Specific Implementation Methods One to Three.

[0041] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that: the volume ratio of solution B to solution A in step one ③ is 1:1; the aging time in step one ③ is 20h to 26h. Other steps are the same as in Specific Implementation Methods One to Four.

[0042] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that: the continuous stirring time in step one ③ is 2 to 4 hours; in step one ③, the precipitate is first washed by centrifugation with deionized water 3 to 5 times, then washed by centrifugation with anhydrous ethanol 3 to 5 times, and then dried at 60°C to 80°C for 4 to 8 hours. Other steps are the same as in Specific Implementation Methods One to Five.

[0043] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that: the mass ratio of thioacetamide to anhydrous ethanol in step two ① is (150mg~250mg):(15mL~25mL); the mass ratio of thioacetamide to nickel-cobalt-iron Prussian blue in step two ① is (150~250):(60~90). The other steps are the same as in Specific Implementation Methods One to Six.

[0044] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that: the ultrasonic dispersion time in step two① is 1 min to 5 min; the stirring time in step two① is 10 min to 30 min; step two

[0045] The heat preservation time described in section ② is 4 to 12 hours. The other steps are the same as those in specific implementation methods one to seven.

[0046] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that: in step two ②, the reaction product is centrifuged and washed 3 to 5 times with anhydrous ethanol, and then vacuum dried at 60℃ to 80℃ for 4 to 8 hours. The other steps are the same as in Specific Implementation Methods One to Eight.

[0047] Specific Implementation Method 10: This implementation method is to use a ternary Prussian blue derived nanocage core-shell electrode material as a supercapacitor.

[0048] The beneficial effects of the present invention are verified using the following embodiments:

[0049] Example 1: A method for preparing a ternary Prussian blue-derived nanocage core-shell electrode material, specifically completed according to the following steps:

[0050] I. Preparation of Nickel-Cobalt-Iron Prussian Blue:

[0051] ① Dissolve 2 mmol Ni(CH3COO)2·4H2O, 1 mmol Co(CH3COO)2·4H2O and 4 mmol Na3C6H5O7·2H2O in 80 mL of deionized water to obtain solution A;

[0052] ② Dissolve 1 mmol of K3[Fe(CN)6] in 80 mL of deionized water to obtain solution B;

[0053] ③ Add solution B obtained in step 1 ② to solution A in step 1 ①, and stir continuously for 3 hours to obtain mixed solution I; age mixed solution I at room temperature for 24 hours to obtain precipitate; wash the precipitate three times with deionized water by centrifugation, then wash the precipitate three times with anhydrous ethanol by centrifugation, and then dry it at 60℃ for 6 hours to obtain nickel cobalt iron Prussian blue (NiCoFe PBA);

[0054] II. Preparation of core-shell electrode materials:

[0055] ① Dissolve 200 mg of thioacetamide in 20 mL of anhydrous ethanol, then add 80 mg of nickel cobalt iron Prussian blue, sonicate for 3 min, and then stir for 20 min to obtain mixed solution II;

[0056] ② Transfer the mixed solution II to a high-pressure reactor, seal it, and place it in a high-temperature oven. Keep it at 160°C for 8 hours, and then let it cool naturally to room temperature to obtain the reaction product. Wash the reaction product three times by centrifugation with anhydrous ethanol, and then dry it at 60°C for 6 hours to obtain the ternary Prussian blue derived nanocage core-shell electrode material (NCFS@PBA).

[0057] Figure 1 The images are SEM images. In the image, (a) is the nickel-cobalt-iron Prussian blue prepared in step one of Example 1, and (b) is the ternary Prussian blue-derived nanocage core-shell electrode material prepared in step two of Example 1.

[0058] Figure 1 (a) is a scanning electron microscope image of NiCoFePBA. As can be seen from the image, NiCoFePBA material has a smooth surface and curved apex cubic structure with a diameter of about 220 nm. Figure 1 (b) is a scanning electron microscope image of the NCFS@PBA core-shell electrode material after sulfidation. As can be seen from the figure, the cubic material structure is well maintained after sulfidation, indicating that the core-shell material has good structural stability.

[0059] Figure 2 Transmission electron microscopy (TEM) images at different magnifications of the ternary Prussian blue-derived nanocage core-shell electrode material prepared in step two of Example 1;

[0060] Figure 2 (a) shows the internal structure of the NCFS@PBA core-shell cubic material. The PBA outer shell of the cube remains undeformed, ensuring the stability of the cube; the interior of the cube contains numerous nanoparticles, which are multi-metal sulfides (NCFS), providing a high specific capacity. Furthermore, Figure 2 (b) The thickness of the outer shell is approximately 20.7 nm, and the measured interplanar spacing is 0.511 nm, corresponding to the 200 crystal plane of NiCoFePBA. Figure 2 (c) The lattice spacing of the multi-metallic sulfide (NCFS) inside the cube is shown. The measured interplanar spacings are 0.247 nm and 0.278 nm, pointing to the 210 plane of CoS2 and the 200 plane of (Ni,Fe)S2, respectively.

[0061] Figure 3 The X-ray diffraction pattern of the ternary Prussian blue-derived nanocage core-shell electrode material prepared in step two of Example 1;

[0062] The X-ray diffraction pattern of the NCFS@PBA core-shell electrode material is as follows: Figure 3 As shown, the diffraction peaks at 2Theta of 24.5°, 34.9°, 43.2°, and 50.3° are characteristic peaks of nickel-cobalt-iron Prussian blue, corresponding to the (220), (400), (422), and (440) crystal planes of face-centered cubic Prussian blue, respectively. Furthermore, the diffraction peaks at 32.2°, 36.2°, 46.3°, and 55° are assigned to CoS2 (JCPDS No. 89-1492) and (Ni,Fe)S2 (JCPDS No. 88-1710). The XRD pattern also confirms the formation of the NCFS@PBA core-shell material.

[0063] Figure 4 Cyclic voltammetry curves of the ternary Prussian blue-derived nanocage core-shell electrode material prepared in step two of Example 1 at different scan rates;

[0064] from Figure 4 It can be seen that obvious redox peaks can be observed in the cyclic voltammetry curves, indicating that a Faraday reaction exists in the electrode during energy storage, which is attributed to a battery-type charge storage mechanism. When the scan rate increases from 10 mV / s to 100 mV / s, the shape of the cyclic voltammetry curves does not change significantly, indicating that the core-shell electrode material has good capacitance performance.

[0065] Figure 5 The constant current charge-discharge curves of the ternary Prussian blue-derived nanocage core-shell electrode material prepared in step two of Example 1 at different current densities are shown.

[0066] from Figure 5 As can be seen, the charge-discharge curves exhibit a distinct voltage plateau, a characteristic of the Faraday reaction during energy storage. The approximately equal charge-discharge times indicate that the core-shell electrode material possesses high coulombic efficiency. Furthermore, the charge-discharge curves do not show significant deformation with increasing current density, suggesting that the core-shell electrode material exhibits good rate performance.

[0067] Figure 6 The graph shows the cycling performance of the ternary Prussian blue-derived nanocage core-shell electrode material prepared in step two of Example 1 at a current density of 15 A / g.

[0068] from Figure 6 It can be seen that the capacitance retention rate reaches 97.27% after 6000 charge-discharge cycles, indicating that the core-shell material has excellent cycle performance.

[0069] Figure 7 The constant current charge-discharge curves of the nickel-cobalt-iron Prussian blue prepared in step one of Example 1 and the ternary Prussian blue-derived nanocage core-shell electrode materials prepared in step two of Example 1 are shown at a current density of 1 A / g.

[0070] from Figure 7 It can be seen that the charge-discharge curve of the nickel-cobalt-iron Prussian blue (NiCoFe PBA) prepared in step one of Example 1 exhibits a voltage plateau, which is characteristic of the redox reaction during energy storage. In contrast, the ternary Prussian blue-derived nanocage core-shell electrode material (NCFS@PBA) prepared in step two of Example 1 has a wider reaction potential and a longer reaction duration. This indicates that the prepared NCFS@PBA nanocage core-shell material exhibits enhanced redox reaction and significantly improved specific capacitance compared to the NICoFe PBA material.

Claims

1. A method for preparing a ternary prussian blue derivative nanocage core-shell electrode material, characterized in that the method is completed according to the following steps: Preparation of nickel-cobalt-iron prussian blue: ①, Ni (CH3COO) 2·4H2O, Co (CH3COO) 2·4H2O and Na3C6H5O7·2H2O are dissolved in deionized water to obtain solution A; The mass ratio of Ni (CH3COO) 2·4H2O, Co (CH3COO) 2·4H2O and Na3C6H5O7·2H2O in step 1 ① is 2:1:(2~4); The volume ratio of the mass of Ni (CH3COO) 2·4H2O in step 1 ① to deionized water is (1mmol~3mmol):(60mL~100mL); ②, K3[Fe (CN) 6] is dissolved in deionized water to obtain solution B; The mass ratio of K3[Fe (CN) 6] in step 1 ② to Ni (CH3COO) 2·4H2O in step 1 ① is (1~2):2; ③, solution B is added dropwise to solution A, and continuous stirring is performed to obtain mixed solution I; The mixed solution I is aged at room temperature to obtain a precipitate, which is washed and dried to obtain nickel-cobalt-iron prussian blue; The volume ratio of solution B to solution A in step 1 ③ is 1:1; the aging time in step 1 ③ is 20h~26h; Preparation of core-shell electrode material: ①, thioacetamide is dissolved in anhydrous ethanol, and then nickel-cobalt-iron prussian blue is added, ultrasonic dispersion is performed, and then stirring is performed to obtain mixed solution II; The volume ratio of the mass of thioacetamide in step 2 ① to the volume of anhydrous ethanol is (150mg~250mg):(15mL~25mL); The mass ratio of thioacetamide to nickel-cobalt-iron prussian blue in step 2 ① is (150~250):(60~90); ②, the mixed solution II is transferred to a high-pressure reaction kettle, sealed and placed in a high-temperature oven, and then incubated at 150°C~170°C for 4h~12h, and then naturally cooled to room temperature to obtain a reaction product; the reaction product is washed and vacuum dried to obtain a ternary prussian blue derivative nanocage core-shell electrode material; the material is a nanocage core-shell cube formed by taking ternary prussian blue as a shell and a derived metal sulfide nanoparticle as a core, wherein the thickness of the shell is 15~25nm, and the diameter of the nanocage core-shell cube is 150~350nm; the ternary prussian blue derivative nanocage core-shell electrode material is used as a supercapacitor electrode. The continuous stirring time in step 1 ③ is 2h~4h; first, the precipitate is centrifugally washed with deionized water for 3~5 times in step 1 ③, and then the precipitate is centrifugally washed with anhydrous ethanol for 3~5 times, and then dried at 60°C~80°C for 4h~8h.

2. The method of claim 1, wherein the method is characterized by The ultrasonic dispersion time in step 2 ① is 1min~5min; the stirring time in step 2 ① is 10min~30min.

3. The method of claim 1, wherein the method is characterized by ​ 4. The method of claim 1, wherein the method is characterized by The reaction product is washed 3-5 times by centrifugation with anhydrous ethanol in step two ②, and then vacuum dried at 60-80℃ for 4-8h.

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