Nickel-cobalt-aluminum hydroxide, and preparation method and application thereof

Abstract

The application relates to the technical field of electrode materials, in particular to a nickel-cobalt-aluminum hydroxide as well as a preparation method and application thereof. The preparation method provided by the application comprises the following steps: mixing a soluble nickel source, a soluble cobalt source, a soluble aluminum source, oxalic acid and water, and then performing a hydrothermal reaction to obtain a nickel-cobalt-aluminum oxalate compound precursor with a sheet-shaped self-assembled spherical structure; mixing the nickel-cobalt-aluminum oxalate compound precursor with the sheet-shaped self-assembled spherical structure, water and sodium hydroxide to obtain the nickel-cobalt-aluminum hydroxide. The nickel-cobalt-aluminum hydroxide prepared by the preparation method has excellent electrochemical performance.

Description

A nickel-cobalt-aluminum hydroxide, its preparation method and application Technical Field

[0001] This invention relates to the field of electrode materials technology, and in particular to a nickel-cobalt-aluminum hydroxide, its preparation method, and its application. Background Technology

[0002] Faced with escalating energy shortages and increasingly severe environmental pollution, there is an urgent need to develop new energy storage systems to meet growing energy demands and reduce dependence on traditional fossil fuels. This challenge has spurred extensive research into energy storage devices with high specific energy, high specific power, long cycle life, and environmental friendliness. Supercapacitors, as a high-efficiency, low-cost, and environmentally friendly energy storage device, have attracted widespread attention due to their advantages such as high power density, long cycle life, excellent rate performance, rapid charging and discharging, and energy conservation. The electrode materials of supercapacitors, as one of their core components, directly determine the overall performance of the device.

[0003] Layered metal hydroxides are a rapidly developing electrode material, especially nickel-cobalt-based metal hydroxides. Nickel-cobalt-based metal hydroxides exhibit good redox reversibility, fast reaction rates, large specific surface areas, and are easily fabricated into layered microstructures, making them a promising electrode material for supercapacitors. However, while nickel-cobalt-based transition metal hydroxides possess high electrochemical reactivity, they still face challenges in simultaneously improving specific capacitance and rate performance, and the exploration of electrode material design and synthesis methods is relatively limited. Summary of the Invention

[0004] The purpose of this invention is to provide a nickel-cobalt-aluminum hydroxide, its preparation method, and its applications. The nickel-cobalt-aluminum hydroxide prepared by the method exhibits excellent electrochemical performance.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for preparing nickel-cobalt-aluminum hydroxide, comprising the following steps:

[0007] A soluble nickel source, a soluble cobalt source, a soluble aluminum source, oxalic acid and water are mixed and subjected to a hydrothermal reaction to obtain a nickel-cobalt-aluminum oxalic acid compound precursor with a sheet-like self-assembled spherical structure.

[0008] The nickel cobalt aluminum oxalate compound precursor with a sheet-like self-assembled spherical structure was mixed with water and sodium hydroxide to obtain nickel cobalt aluminum hydroxide.

[0009] Preferably, the molar ratio of the soluble nickel source to the soluble cobalt source is 1:4 to 4:1.

[0010] Preferably, the molar ratio of the soluble nickel source to the soluble aluminum source is 1:(0.025~0.25).

[0011] Preferably, the molar ratio of the soluble nickel source to oxalic acid is 1:4.

[0012] Preferably, the hydrothermal reaction is carried out at a temperature of 40–120°C for a duration of 4–8 hours.

[0013] Preferably, after the hydrothermal reaction is completed, the process further includes sequential cooling, washing, and drying.

[0014] Preferably, the mass ratio of the nickel cobalt aluminum oxalate compound precursor with a sheet-like self-assembled spherical structure, water, and sodium hydroxide is 183 mg: 60 mL: (80–400) mg.

[0015] The present invention also provides a nickel-cobalt-aluminum hydroxide prepared by the preparation method described above, wherein the nickel-cobalt-aluminum hydroxide has a sheet-like self-assembled spherical structure.

[0016] The present invention also provides the application of the nickel-cobalt-aluminum hydroxide described in the above technical solution as an electrode material in supercapacitors.

[0017] This invention provides a method for preparing nickel-cobalt-aluminum hydroxide, comprising the following steps: mixing a soluble nickel source, a soluble cobalt source, a soluble aluminum source, oxalic acid, and water, and then performing a hydrothermal reaction to obtain a nickel-cobalt-aluminum oxalic acid compound precursor with a sheet-like self-assembled spherical structure; mixing the nickel-cobalt-aluminum oxalic acid compound precursor with the sheet-like self-assembled spherical structure, water, and sodium hydroxide to obtain nickel-cobalt-aluminum hydroxide. This invention employs a simple chemical precipitation method and a hydrothermal method to prepare nickel-cobalt-aluminum oxalic acid compounds. Using these as precursors, a sheet-like self-assembled spherical structure of nickel-cobalt-aluminum hydroxide is prepared through an anion exchange reaction with sodium hydroxide. The preparation method proposed in this invention has the advantages of being scientifically sound, safe and easy to implement, requiring simple equipment, having low cost, and allowing for controllable product morphology and structure. The prepared electrode material exhibits excellent electrochemical performance and is suitable for the large-scale, controllable preparation of high-performance supercapacitor electrode materials. The nickel-cobalt-aluminum hydroxide prepared by the method has a sheet-like self-assembled spherical structure with a large specific surface area, which is more conducive to the full contact between the electrolyte solution and the electrode material, accelerating the rapid transport of ions and giving the material high electrochemical reactivity and conductivity. At the same time, the multi-metal composition of nickel-cobalt-aluminum hydroxide can effectively regulate its electronic structure, and by utilizing the synergistic complementary effect between metals, the charge storage capacity of the material can be effectively improved, thereby increasing the energy density and power density of supercapacitors based on this material. Attached Figure Description

[0018] Figure 1 is a scanning electron microscope image of the nickel cobalt aluminum oxalate compound precursor described in Example 4;

[0019] Figure 2 is a scanning electron microscope image of the nickel-cobalt-aluminum hydroxide described in Example 4;

[0020] Figure 3 is an X-ray energy dispersive spectroscopy (EDS) spectrum of the nickel-cobalt-aluminum hydroxide described in Example 4;

[0021] Figure 4 is an X-ray diffraction pattern of the nickel cobalt aluminum oxalate compound precursor described in Example 4;

[0022] Figure 5 is the X-ray diffraction pattern of the nickel-cobalt-aluminum hydroxide described in Example 4;

[0023] Figure 6 is an X-ray photoelectron spectroscopy analysis diagram of the nickel-cobalt-aluminum hydroxide electrode material described in Example 4;

[0024] Figure 7 shows the nickel-cobalt-aluminum hydroxide electrode material described in Example 4 at 5–50 mV·s. -1 CV curves at scan rates;

[0025] Figure 8 is the GCD diagram of the nickel-cobalt-aluminum hydroxide electrode material described in Example 4;

[0026] Figure 9 shows the GCD diagram of the nickel-cobalt-aluminum hydroxide electrode materials described in Examples 1-5. Detailed Implementation

[0027] This invention provides a method for preparing nickel-cobalt-aluminum hydroxide, comprising the following steps:

[0028] A soluble nickel source, a soluble cobalt source, a soluble aluminum source, oxalic acid and water are mixed and subjected to a hydrothermal reaction to obtain a nickel-cobalt-aluminum oxalic acid compound precursor with a sheet-like self-assembled spherical structure.

[0029] The nickel cobalt aluminum oxalate compound precursor with a sheet-like self-assembled spherical structure was mixed with water and sodium hydroxide to obtain nickel cobalt aluminum hydroxide.

[0030] In this invention, unless otherwise specified, all raw materials used in the preparation are commercially available products well known to those skilled in the art.

[0031] This invention involves mixing a soluble nickel source, a soluble cobalt source, a soluble aluminum source, oxalic acid, and water, and then subjecting the mixture to a hydrothermal reaction to obtain a nickel-cobalt-aluminum oxalic acid compound precursor with a sheet-like self-assembled spherical structure.

[0032] In this invention, the soluble nickel source is preferably one or more of nickel chloride (NiCl2·6H2O), nickel sulfate (NiSO4·6H2O), and nickel nitrate (Ni(NO3)2·6H2O), more preferably nickel chloride (NiCl2·6H2O); when the soluble nickel source is two or more of the above-mentioned specific selections, this invention does not have any special limitation on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio.

[0033] In this invention, the soluble cobalt source preferably includes one or more of cobalt nitrate (Co(NO3)2·6H2O), cobalt chloride (CoCl2·6H2O), and cobalt sulfate (CoSO4·7H2O), more preferably cobalt nitrate; when the soluble cobalt source is two or more of the above-mentioned specific selections, this invention does not impose any special limitation on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio.

[0034] In this invention, the soluble aluminum salt preferably includes one or more of aluminum nitrate (Al(NO3)3·9H2O), aluminum sulfate (Al2(SO4)3·18H2O), and sodium aluminate (NaAlO2), more preferably aluminum nitrate; when the soluble aluminum salt is two or more of the above-mentioned specific selections, this invention does not have any special limitation on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio.

[0035] In this invention, the oxalic acid is preferably H2C2O4·2H2O.

[0036] In this invention, the water is preferably ultrapure water.

[0037] In this invention, the molar ratio of the soluble nickel source to the soluble cobalt source is preferably 1:4 to 4:1, more preferably 1:3 to 3:1, and most preferably 1:2 to 2:1; the molar ratio of the soluble nickel source to the soluble aluminum source is preferably 1:(0.025 to 0.25), more preferably 1:(0.05 to 0.2), and most preferably 1:(0.1 to 0.15); the molar ratio of the soluble nickel source to oxalic acid is preferably 1:4.

[0038] In this invention, the mixing is preferably carried out under stirring conditions; the stirring method is preferably mechanical stirring. The mechanical stirring time is preferably 4 hours. This invention does not impose any special limitation on the speed of the mechanical stirring; any speed well known to those skilled in the art can be used.

[0039] In this invention, the concentration of soluble nickel salt in the mixture obtained by mixing is preferably 0.00625 to 0.025 mmol / L, more preferably 0.0125 to 0.025 mmol / L, and most preferably 0.025 mmol / L.

[0040] In this invention, the temperature of the hydrothermal reaction is preferably 40–120°C, more preferably 80–120°C, and most preferably 120°C; the time is preferably 4–8 hours, more preferably 4–6 hours, and most preferably 4 hours. In this invention, the hydrothermal reaction serves to generate a sheet-like self-assembled spherical structure from nickel-cobalt-aluminum hydroxide.

[0041] After the hydrothermal reaction is completed, the present invention preferably includes sequential cooling, washing, and drying. The present invention does not impose any special limitations on the cooling process; a process well-known to those skilled in the art can be used to cool to room temperature. In the present invention, the washing preferably includes washing three times with ultrapure water and three times with anhydrous ethanol. In the present invention, the drying temperature is preferably 50–80°C, more preferably 50–60°C, and most preferably 50°C; the drying time is preferably 8–12 hours, more preferably 10–12 hours, and most preferably 12 hours.

[0042] After obtaining the nickel cobalt aluminum oxalate compound precursor with a sheet-like self-assembled spherical structure, the nickel cobalt aluminum oxalate compound precursor with a sheet-like self-assembled spherical structure, water, and sodium hydroxide are mixed to obtain nickel cobalt aluminum hydroxide.

[0043] In this invention, the water is preferably ultrapure water.

[0044] In this invention, the mass ratio of the nickel cobalt aluminum oxalate compound precursor with a sheet-like self-assembled spherical structure, water, and sodium hydroxide is preferably 183 mg: 60 mL: (80-400) mg, more preferably 183 mg: 60 mL: (100-300) mg, and most preferably 183 mg: 60 mL: (150-250) mg.

[0045] In this invention, the mixing is preferably carried out by dispersing the nickel cobalt aluminum oxalate compound precursor with a sheet-like self-assembled spherical structure in water, adding sodium hydroxide, and stirring; the stirring temperature is preferably room temperature, and the stirring time is preferably 13 hours; this invention does not impose any special limitation on the stirring speed, and any speed known to those skilled in the art can be used.

[0046] After the mixing is completed, the present invention preferably includes sequential washing and drying; the washing is preferably performed by washing three times with ultrapure water and three times with anhydrous ethanol. The drying method is preferably oven drying; the drying temperature is preferably 50°C and the drying time is preferably 12 hours; the drying is preferably carried out in a forced-air drying oven.

[0047] The present invention also provides a nickel-cobalt-aluminum hydroxide prepared by the preparation method described above, wherein the nickel-cobalt-aluminum hydroxide has a sheet-like self-assembled spherical structure.

[0048] This invention also provides the application of the nickel-cobalt-aluminum hydroxide described in the above technical solution as an electrode material in supercapacitors. This invention does not impose any special limitations on the method of application; any method well-known to those skilled in the art can be used.

[0049] The following detailed description, in conjunction with embodiments, illustrates the nickel-cobalt-aluminum hydroxide, its preparation method, and its applications provided by the present invention. However, these descriptions should not be construed as limiting the scope of protection of the present invention.

[0050] Example 1

[0051] 0.5 mmol nickel chloride (NiCl2·6H2O), 2 mmol cobalt nitrate (Co(NO3)2·6H2O), 0.05 mmol aluminum nitrate (Al(NO3)3·9H2O), and 8 mmol oxalic acid (H2C2O4·2H2O) were dissolved in 80 mL of ultrapure water and stirred magnetically at room temperature for 4 h. The mixture was then transferred to a stainless steel reactor lined with polytetrafluoroethylene and reacted at 120 °C for 4 h. After naturally cooling to room temperature, the mixture was washed three times with ultrapure water and then three times with anhydrous ethanol. The washed product was placed in a forced-air drying oven and dried at 50 °C for 12 h to obtain a nickel cobalt aluminum oxalic acid compound precursor with a sheet-like self-assembled spherical structure.

[0052] 183 mg of the nickel cobalt aluminum oxalic acid compound precursor was uniformly dispersed in 60 mL of ultrapure water, 80 mg of NaOH was added, and the mixture was stirred at room temperature for 13 h. After washing three times with ultrapure water and three times with anhydrous ethanol, the washed product was placed in a forced-air drying oven and dried at 50 °C for 12 h to obtain nickel cobalt aluminum hydroxide (a ternary metal hydroxide electrode material with a sheet-like self-assembled spherical structure).

[0053] Example 2

[0054] 1 mmol nickel chloride (NiCl2·6H2O), 2 mmol cobalt nitrate (Co(NO3)2·6H2O), 0.1 mmol aluminum nitrate (Al(NO3)3·9H2O), and 8 mmol oxalic acid (H2C2O4·2H2O) were dissolved in 80 mL of ultrapure water and magnetically stirred at room temperature for 4 h. The mixture was then transferred to a stainless steel reactor lined with polytetrafluoroethylene and reacted at 120 °C for 4 h. After naturally cooling to room temperature, the mixture was washed three times with ultrapure water and then three times with anhydrous ethanol. The washed product was placed in a forced-air drying oven and dried at 50 °C for 12 h to obtain a nickel cobalt aluminum oxalic acid compound precursor with a sheet-like self-assembled spherical structure.

[0055] 183 mg of the nickel cobalt aluminum oxalic acid compound precursor was uniformly dispersed in 60 mL of ultrapure water, 160 mg of NaOH was added, and the mixture was stirred at room temperature for 13 h. After washing three times with ultrapure water and three times with anhydrous ethanol, the washed product was placed in a forced-air drying oven and dried at 50 °C for 12 h to obtain nickel cobalt aluminum hydroxide (a ternary metal hydroxide electrode material with a sheet-like self-assembled spherical structure).

[0056] Example 3

[0057] 2 mmol of nickel chloride (NiCl2·6H2O), 2 mmol of cobalt nitrate (Co(NO3)2·6H2O), 0.3 mmol of aluminum nitrate (Al(NO3)3·9H2O), and 8 mmol of oxalic acid (H2C2O4·2H2O) were dissolved in 80 mL of ultrapure water and stirred magnetically at room temperature for 4 h. The mixture was then transferred to a stainless steel reactor lined with polytetrafluoroethylene and reacted at 120 °C for 4 h. After naturally cooling to room temperature, the mixture was washed three times with ultrapure water and then three times with anhydrous ethanol. The washed product was placed in a forced-air drying oven and dried at 50 °C for 12 h to obtain a nickel cobalt aluminum oxalic acid compound precursor with a sheet-like self-assembled spherical structure.

[0058] 183 mg of the nickel cobalt aluminum oxalic acid compound precursor was uniformly dispersed in 60 mL of ultrapure water, 240 mg of NaOH was added, and the mixture was stirred at room temperature for 13 h. After washing three times with ultrapure water and three times with anhydrous ethanol, the washed product was placed in a forced-air drying oven and dried at 50 °C for 12 h to obtain nickel cobalt aluminum hydroxide (a ternary metal hydroxide electrode material with a sheet-like self-assembled spherical structure).

[0059] Example 4

[0060] 2 mmol of nickel chloride (NiCl2·6H2O), 1 mmol of cobalt nitrate (Co(NO3)2·6H2O), 0.1 mmol of aluminum nitrate (Al(NO3)3·9H2O), and 8 mmol of oxalic acid (H2C2O4·2H2O) were dissolved in 80 mL of ultrapure water and stirred magnetically at room temperature for 4 h. The mixture was then transferred to a stainless steel reactor lined with polytetrafluoroethylene and reacted at 120 °C for 4 h. After naturally cooling to room temperature, the mixture was washed three times with ultrapure water and then three times with anhydrous ethanol. The washed product was placed in a forced-air drying oven and dried at 50 °C for 12 h to obtain a nickel cobalt aluminum oxalic acid compound precursor with a sheet-like self-assembled spherical structure.

[0061] 183 mg of the nickel cobalt aluminum oxalic acid compound precursor was uniformly dispersed in 60 mL of ultrapure water, 320 mg of NaOH was added, and the mixture was stirred at room temperature for 13 h. The product was then washed three times with ultrapure water and three times with anhydrous ethanol. The washed product was placed in a forced-air drying oven and dried at 50 °C for 12 h to obtain nickel cobalt aluminum hydroxide (a ternary metal hydroxide electrode material with a sheet-like self-assembled spherical structure).

[0062] Figure 1 is a scanning electron microscope (SEM) image of the nickel cobalt aluminum oxalate compound precursor, and Figure 2 is a scanning electron microscope (SEM) image of the nickel cobalt aluminum hydroxide. As can be seen from Figures 1 and 2, both the nickel cobalt aluminum oxalate compound precursor and the nickel cobalt aluminum hydroxide are sheet-like self-assembled spherical structures. The nickel cobalt aluminum hydroxide has a layered nanosphere structure, which can increase the contact area between the electrolyte solution and the electrode material, which is beneficial to the rapid transport of ions and gives the material high specific capacitance and rate performance.

[0063] Figure 3 shows the X-ray energy dispersive spectroscopy (EDS) spectrum of the nickel cobalt aluminum hydroxide. As can be seen from Figure 3, the nickel cobalt aluminum hydroxide is composed of four elements: Ni, Co, Al and O, and the elements are evenly distributed.

[0064] Figure 4 shows the X-ray diffraction (XRD) pattern of the nickel-cobalt-aluminum oxalate compound precursor, and Figure 5 shows the X-ray diffraction (XRD) pattern of the nickel-cobalt-aluminum hydroxide. As can be seen from Figures 4 and 5, the characteristic peaks of the nickel-cobalt-aluminum oxalate compound are consistent with those of NiC2O4·2H2O (JCPDS25-0581) and CoC2O4·2H2O (JCPDS25-0250). Since the characteristic peaks of the two components are relatively strong, and the aluminum content is relatively low, the characteristic peak of aluminum oxalate is not obvious. The crystal planes corresponding to the diffraction peaks in the XRD pattern of the nickel-cobalt-aluminum hydroxide conform to the (006), (012), (015), (018), (110), and (202) crystal planes of NiCo-OH, indicating that the electrode material is composed of three metal hydroxides.

[0065] Figure 6 shows the X-ray photoelectron spectroscopy (XPS) analysis of the nickel-cobalt-aluminum hydroxide electrode material, where a is the full spectrum, b is the characteristic peak of Ni 2P, c is the characteristic peak of Co 2P, d is the characteristic peak of Al 2P, and e is the characteristic peak of O 1s. As can be seen from Figure 6, the XPS shows obvious characteristic peaks of Ni, Co, Al, and O elements, indicating that the composite material is composed of these four elements.

[0066] Using the aforementioned nickel-cobalt-aluminum hydroxide electrode material as the working electrode, a platinum sheet electrode as the counter electrode, an Hg / HgO electrode as the reference electrode, and a 2 mol / L KOH solution as the electrolyte solution, the voltage is maintained at 5–50 mV·s. -1Cyclic voltammetry (CV) tests were performed at a scan rate of 5–50 mV·s, where Figure 7 shows the nickel-cobalt-aluminum hydroxide electrode material at 5–50 mV·s. -1 As shown in Figure 7, each complete cyclic voltammetry curve has a pair of obvious redox peaks, which confirms that the prepared electrode material is a battery-type energy storage material, and that a reversible Faraday redox reaction occurred during the electrochemical energy storage process.

[0067] Using the nickel-cobalt-aluminum hydroxide electrode material as the working electrode, a platinum sheet electrode as the counter electrode, an Hg / HgO electrode as the reference electrode, and a 2 mol / L KOH solution as the electrolyte solution, constant current charge-discharge (GCD) tests were performed. Figure 8 shows the GCD curve of the nickel-cobalt-aluminum hydroxide electrode material. As can be seen from Figure 8, the constant current charge-discharge curves obtained at different current densities have obvious charge-discharge plateaus, further indicating that the prepared material is a battery-type energy storage material, which is consistent with the cyclic voltammetry analysis. Calculations show that at 1 A·g -1 2A·g -1 3A·g -1 5A·g -1 8A·g -1 10A·g -1 15A·g -1 and 20A·g -1 At current densities of , the specific capacitance of the materials is 1680 F·g -1 1560F·g -1 1480F·g -1 1365F·g -1 1235F·g -1 1162F·g -1 990F·g -1 and 849F·g -1 The results showed that the prepared nickel-cobalt-aluminum hydroxide had excellent charge storage capacity.

[0068] Example 5

[0069] 2 mmol of nickel chloride (NiCl2·6H2O), 0.5 mmol of cobalt nitrate (Co(NO3)2·6H2O), 0.5 mmol of aluminum nitrate (Al(NO3)3·9H2O), and 8 mmol of oxalic acid (H2C2O4·2H2O) were dissolved in 80 mL of ultrapure water and stirred magnetically at room temperature for 4 h. The mixture was then transferred to a stainless steel reactor lined with polytetrafluoroethylene and reacted at 120 °C for 4 h. After naturally cooling to room temperature, the mixture was washed three times with ultrapure water and then three times with anhydrous ethanol. The washed product was placed in a forced-air drying oven and dried at 50 °C for 12 h to obtain a nickel cobalt aluminum oxalic acid compound precursor with a sheet-like self-assembled spherical structure.

[0070] 183 mg of the nickel cobalt aluminum oxalic acid compound precursor was uniformly dispersed in 60 mL of ultrapure water, 400 mg of NaOH was added, and the mixture was stirred at room temperature for 13 h. After washing three times with ultrapure water and three times with anhydrous ethanol, the washed product was placed in a forced-air drying oven and dried at 50 °C for 12 h to obtain nickel cobalt aluminum hydroxide (a ternary metal hydroxide electrode material with a sheet-like self-assembled spherical structure).

[0071] This invention uses the nickel-cobalt-aluminum hydroxide electrode material described in Examples 1-5 as the working electrode, a platinum sheet electrode as the counter electrode, an Hg / HgO electrode as the reference electrode, and a 2 mol / L KOH solution as the electrolyte solution, at a current density of 1 A·g -1 and 20A·g -1 Constant current charge-discharge (GCD) tests were conducted. As shown in Figure 9, the electrochemical performance test results of the nickel-cobalt-aluminum hydroxide electrode materials in Examples 1-5 show that at a current density of 1 A·g⁻¹… -1 The specific capacitances at those times are 696 F·g -1 1040F·g -1 1058F·g -1 1680F·g -1 and 802F·g -1 At a current density of 20 A·g -1 The specific capacitance retention rates were 69%, 73%, 57%, 51%, and 22%, respectively, indicating that the nickel-cobalt-aluminum hydroxide prepared in Example 4 had the best electrochemical performance and good rate performance.

[0072] In summary, this invention prepares nickel-cobalt-aluminum oxalate compounds using chemical precipitation and hydrothermal methods. Using these ternary metal oxalate compounds as precursors, nickel-cobalt-aluminum hydroxide electrode materials with a sheet-like self-assembled spherical structure are prepared via anion exchange reaction. By adjusting reaction parameters and optimizing preparation conditions, the material preparation method was determined. The preparation method described in this invention has the advantages of being scientifically sound, safe, easy to implement, requiring simple equipment, low cost, and allowing for controllable product morphology and structure. Furthermore, by fully utilizing the synergistic and complementary effects between different metals, the electrochemical reactivity of the electrode material is improved, thereby enhancing its specific capacitance and rate performance. The material prepared by this invention has promising application prospects as a supercapacitor electrode material.

[0073] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing nickel-cobalt-aluminum hydroxide, characterized in that, The process includes the following steps: mixing a soluble nickel source, a soluble cobalt source, a soluble aluminum source, oxalic acid, and water, and then performing a hydrothermal reaction to obtain a nickel-cobalt-aluminum oxalic acid compound precursor with a sheet-like self-assembled spherical structure; mixing the nickel-cobalt-aluminum oxalic acid compound precursor with a sheet-like self-assembled spherical structure, water, and sodium hydroxide to obtain nickel-cobalt-aluminum hydroxide; the hydrothermal reaction is performed at a temperature of 120°C for 4 hours; the nickel-cobalt-aluminum hydroxide has a sheet-like self-assembled spherical structure; the molar ratio of the soluble nickel source to the soluble cobalt source is 1:4 to 4:1; and the molar ratio of the soluble nickel source to the soluble aluminum source is 1:(0.025 to 0.25).

2. The preparation method according to claim 1, characterized in that, The molar ratio of the soluble nickel source to oxalic acid is 1:

4.

3. The preparation method according to claim 1, characterized in that, After the hydrothermal reaction is completed, the process also includes sequential cooling, washing, and drying.

4. The preparation method according to claim 1, characterized in that, The mass ratio of the nickel cobalt aluminum oxalate compound precursor with a sheet-like self-assembled spherical structure, water, and sodium hydroxide is 183 mg: 60 mL: (80~400) mg.

5. The nickel-cobalt-aluminum hydroxide prepared by the preparation method according to any one of claims 1 to 4, characterized in that, The nickel-cobalt-aluminum hydroxide has a sheet-like self-assembled spherical structure.

6. The application of the nickel-cobalt-aluminum hydroxide of claim 5 as an electrode material in supercapacitors.

Images