A chromium-doped nickel molybdate pseudocapacitor anode material and its preparation method and application

Abstract

The present invention discloses a chromium-doped nickel molybdate pseudocapacitive anode material and a preparation method and application thereof, which can be used for supercapacitor anode pseudocapacitive material, and belongs to the field of nanomaterial synthesis and energy environment science and engineering application. The present invention uses a certain amount of chromium element to regulate the microscopic morphology of the initial nickel molybdate solid columnar array. Compared with the undoped solid columnar nickel molybdate, the chromium-doped molybdate material prepared in the present invention has a pseudocapacitance of 9.53 farads per square centimeter when performing a charge and discharge test under constant current density conditions, which is 2.69 times that of the undoped nickel molybdate.

Description

Technical Field

[0001] The invention belongs to the field of nano material synthesis and energy environment science and engineering application, and specifically relates to a chromium-doped nickel molybdate pseudocapacitor anode material and a preparation method and application thereof. Background Art

[0002] The development and utilization of renewable energy sources such as solar energy and wind energy have slowed down the use of fossil fuels and the emission of pollutants to a certain extent. However, renewable energy sources (such as solar energy, wind energy and tidal energy) are intermittent and cannot meet the continuous supply, so a device that can efficiently store and release energy is needed to stably supply energy when needed. Traditional energy storage technology has shortcomings such as short cycle life and slow charging and discharging, which makes it difficult to meet the needs of certain applications. Supercapacitors, as a new type of energy storage device, have attracted much attention due to their high power density, fast charging and discharging speed, long cycle life and no pollution to the environment. High-performance supercapacitors can provide new energy vehicles with longer driving range and faster charging speed, enable renewable energy systems to effectively store and release energy, improve system stability and efficiency, and can also be used as distributed energy storage devices in smart grids to improve the stability and reliability of the grid.

[0003] Anode material is one of the key components of supercapacitors, and its performance directly affects the overall performance of supercapacitors. However, traditional double-layer capacitor materials have certain limitations in energy density and are difficult to meet the growing demand for high-energy-density energy storage. The energy storage mechanism of pseudocapacitor (also known as Faraday pseudocapacitor) materials involves rapid redox reactions on the electrode surface or in the bulk phase, making the energy density much higher than that of traditional double-layer capacitors. However, some precious metal oxide pseudocapacitor anode materials are costly and not conducive to large-scale applications. The development of low-cost and high-performance pseudocapacitor materials is an important research direction. In addition, optimizing the preparation process of anode materials and improving production efficiency are also key to promoting the practical application of pseudocapacitor anode materials. Summary of the invention

[0004] The purpose of the present invention is to use chromium doping to regulate the structure of nickel molybdate, change the morphology of the initial structure to increase the specific surface area of ​​the material, provide more active sites and faster electron transfer efficiency, etc., thereby improving the electrochemical properties of nickel molybdate-based electrode materials. After improving the pseudocapacitive performance of nickel molybdate materials, it can be applied in more fields, especially energy storage devices that require high power density and long cycle life, such as electric vehicles, industrial power, aerospace, and wearable devices.

[0005] The technical solution of the present invention is as follows:

[0006] A chromium-doped nickel molybdate pseudocapacitor anode material is prepared according to the following steps:

[0007] Step 1: Pretreatment of nickel foam: using dilute acid solution, anhydrous ethanol and deionized water for ultrasonic treatment to remove surface oxides and residual pollutants, and then drying for use.

[0008] Step 2: prepare a reaction precursor solution containing a nickel source, a molybdenum source and a chromium source, place the cleaned nickel foam in step 1 in the reaction precursor solution, and use a hydrothermal method to in situ grow a chromium-doped nickel molybdate nanosheet stacked columnar array material on the surface of the nickel foam; after the reaction is completed, take out the nickel foam electrode to obtain a chromium-doped nickel molybdate pseudocapacitor anode material.

[0009] In the above technical solution, the size of the nickel foam in step 1 is 2 3 cm.

[0010] In the above technical solution, the dilute acid used in step 1 is dilute hydrochloric acid, dilute sulfuric acid or dilute nitric acid, and the concentration is about 0.1 mol / L.

[0011] In the above technical solution, in step 1, the nickel foam is ultrasonically treated with dilute acid solution, anhydrous ethanol and deionized water for 10-30 minutes.

[0012] In the above technical solution, in step 2, the nickel source is nickel nitrate hexahydrate, the molybdenum source is ammonium molybdate tetrahydrate, the chromium source is chromium chloride hexahydrate, and the molar mass ratio of the nickel source: molybdenum source: chromium source is 40:10:1 to 40:10:5.

[0013] In the above technical solution, in step 2, the solvent thermal reaction temperature is 150° C. and the reaction time is 5-10 h.

[0014] A method for preparing a chromium-doped nickel molybdate pseudocapacitor anode material comprises the following steps:

[0015] Step 1: Pretreatment of nickel foam, using a dilute acid solution, anhydrous ethanol and deionized water for ultrasonic treatment, respectively, to remove surface oxides and residual pollutants, and then drying to obtain a clean nickel foam;

[0016] Step 2: prepare a reaction precursor solution containing a nickel source, a molybdenum source and a chromium source, place the cleaned nickel foam in step 1 in the reaction precursor solution, and use a hydrothermal method to in situ grow a chromium-doped nickel molybdate nanosheet stacked columnar array material on the surface of the nickel foam; after the reaction is completed, take out the nickel foam to obtain a chromium-doped nickel molybdate pseudocapacitor anode material.

[0017] An application of a chromium-doped nickel molybdate pseudocapacitor anode material is as follows:

[0018] A chromium-doped nickel molybdate pseudocapacitive material described in the above technical solution is directly used as a supercapacitor anode. The cyclic voltammetry curve and the charge-discharge curve are tested using a three-electrode system, wherein the chromium-doped nickel molybdate material is a working electrode, a carbon rod is a counter electrode, a Hg / HgO electrode is a reference electrode, and a potassium hydroxide solution is an electrolyte solution.

[0019] In the above technical solution, the concentration of the potassium hydroxide solution is 1 mol per liter.

[0020] In the above technical solution, the pseudocapacitance of the chromium-doped nickel molybdate anode material is 9.53 farads per square centimeter.

[0021] Beneficial effects:

[0022] 1. Chromium doping regulates the structure of nickel molybdate, changes the original solid columnar morphology, and improves the electron transmission rate of the initial structure.

[0023] 2. Compared with the initial nickel molybdate solid columnar electrode, the chromium-doped nickel molybdate nanosheets stacked columnar array has a larger specific surface area, which in turn increases the cyclic voltammetry area and pseudocapacitance. The pseudocapacitance of chromium-doped nickel molybdate is 9.53 farads per square centimeter, which is 3.94 times that of undoped nickel molybdate.

[0024] 3. The one-step synthesis of chromium-doped nickel molybdate nanosheet stacked columnar arrays is simple to operate, low cost, and beneficial to the expansion of industrial applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 : Scanning electron microscopic image of chromium-doped nickel molybdate prepared by the present invention.

[0026] Figure 2 : Scanning electron microscopic image of nickel molybdate prepared by the present invention.

[0027] Figure 3 : X-ray diffraction spectrum of chromium-doped nickel molybdate prepared by the present invention.

[0028] Figure 4 The chromium-doped nickel molybdate prepared by the present invention and the undoped nickel molybdate have a high conductivity at 5 mA cm -2 Constant current charge and discharge curves under current density.

[0029] Figure 5 : Cyclic voltammetry curves of chromium-doped nickel molybdate prepared by the present invention at different scan rates. DETAILED DESCRIPTION

[0030] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. However, the following embodiments are limited to explaining the present invention, and the protection scope of the present invention should include the entire contents of the claims, and through the description of the following embodiments, those skilled in the art can fully implement the entire contents of the claims of the present invention.

[0031] Embodiment 1:

[0032] ①Cut 2 The samples were 3 cm in size and ultrasonically treated with 0.1 mol / L dilute hydrochloric acid, anhydrous ethanol and deionized water for 10 min respectively to remove surface oxides and pollutants, and then dried for later use.

[0033] ② Prepare 35 ml of reaction precursor liquid containing 40 mmol per liter of nickel nitrate hexahydrate, 10 mmol per liter of ammonium molybdate tetrahydrate, and 2 mmol per liter of chromium chloride hexahydrate, place the pretreated nickel foam and reaction liquid in a 50 ml reactor liner, the reaction temperature is 150 degrees Celsius, the reaction time is 6 hours, after the reaction is completed, rinse with deionized water and anhydrous ethanol and then dry to obtain a chromium-doped nickel molybdate nanosheet array stacked electrode.

[0034] Embodiment 2:

[0035] ①Cut 2 The samples were 3 cm in size and ultrasonically treated with 0.1 mol / L dilute hydrochloric acid, anhydrous ethanol and deionized water for 15 min respectively to remove surface oxides and contaminants, and then dried for later use.

[0036] ② Prepare 35 ml of reaction precursor liquid containing 40 mmol per liter of nickel nitrate hexahydrate, 10 mmol per liter of ammonium molybdate tetrahydrate, and 3 mmol per liter of chromium chloride hexahydrate, place the pretreated nickel foam and reaction liquid in a 50 ml reactor liner, the reaction temperature is 150 degrees Celsius, the reaction time is 7 hours, after the reaction is completed, rinse with deionized water and anhydrous ethanol and then dry to obtain a chromium-doped nickel molybdate nanosheet array stacked electrode.

[0037] Embodiment three:

[0038] ①Cut 2 The samples were 3 cm in size and ultrasonically treated with 0.1 mol / L dilute hydrochloric acid, anhydrous ethanol and deionized water for 15 min respectively to remove surface oxides and contaminants, and then dried for later use.

[0039] ② Prepare 35 ml of reaction precursor liquid containing 40 mmol per liter of nickel nitrate hexahydrate, 10 mmol per liter of ammonium molybdate tetrahydrate, and 4 mmol per liter of chromium chloride hexahydrate, place the pretreated nickel foam and reaction liquid in a 50 ml reactor liner, the reaction temperature is 150 degrees Celsius, the reaction time is 7 hours, after the reaction is completed, rinse with deionized water and anhydrous ethanol and then dry to obtain a chromium-doped nickel molybdate nanosheet array stacked electrode.

[0040] Embodiment 4:

[0041] ①Cut 2 The samples were 3 cm in size and ultrasonically treated with 0.1 mol / L dilute hydrochloric acid, anhydrous ethanol and deionized water for 15 min respectively to remove surface oxides and contaminants, and then dried for later use.

[0042] ② Prepare 35 ml of reaction precursor liquid containing 40 mmol per liter of nickel nitrate hexahydrate, 10 mmol per liter of ammonium molybdate tetrahydrate, and 5 mmol per liter of chromium chloride hexahydrate, place the pretreated nickel foam and reaction liquid in a 50 ml reactor, the reaction temperature is 150 degrees Celsius, the reaction time is 6 hours, after the reaction is completed, rinse with deionized water and anhydrous ethanol and then dry to obtain a chromium-doped nickel molybdate nanosheet array stacked electrode.

[0043] Experimental results:

[0044] In the embodiment of the present invention, a columnar array electrode of chromium-doped nickel molybdate nanosheets was prepared. From the scanning electron microscopy image, it can be seen that there is an obvious sheet-like accumulation morphology in the columnar array structure (such as Figure 1 ), while the undoped nickel molybdate is a solid columnar array with a smooth surface (as shown Figure 2 The X-ray diffraction pattern shows that the X-ray patterns of chromium-doped nickel molybdate and undoped nickel molybdate are consistent (as shown in Figure 2). Figure 3 as shown).

[0045] The chromium-doped nickel molybdate nanosheet stacked columnar array electrode prepared in the embodiment of the present invention is directly used as the pseudocapacitive material of the supercapacitor anode, avoiding the coating process of the powder material. The pseudocapacitive performance of the prepared working electrode is evaluated using a three-electrode system, using 1 mol potassium hydroxide solution as the electrolyte, a carbon rod as the counter electrode, and a Hg / HgO electrode as the reference electrode. Figure 4 This is a constant current charge and discharge curve at a current density of 5 mA per square centimeter. The pseudocapacitance of chromium-doped nickel molybdate is 9.53 farads per square centimeter, which is 2.69 times that of undoped nickel molybdate. Figure 5 The cyclic voltammetry curves of chromium-doped nickel molybdate electrode at different scan rates.

[0046] The present invention does not elaborate on some of the common technologies of those skilled in the art. The above-described embodiments are only descriptions of preferred implementations of the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementations described. Without departing from the design spirit of the present invention, various modifications and improvements made by ordinary technicians in this field to the technical solution of the present invention should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A chromium-doped nickel molybdate pseudocapacitor anode material, characterized in that: Prepared according to the following steps: Step 1: Pretreatment of nickel foam, using a dilute acid solution, anhydrous ethanol and deionized water for ultrasonic treatment, respectively, to remove surface oxides and residual pollutants, and then drying to obtain a clean nickel foam; Step 2: preparing a reaction precursor solution containing a nickel source, a molybdenum source and a chromium source, placing the cleaned nickel foam in step 1 in the reaction precursor solution, and using a hydrothermal method to in-situ grow a chromium-doped nickel molybdate nanosheet stacked columnar array material on the surface of the nickel foam; after the reaction is completed, taking out the nickel foam to obtain a chromium-doped nickel molybdate pseudocapacitor anode material; In step 1, the size of the nickel foam is 2 3 cm, the dilute acid is dilute hydrochloric acid, dilute sulfuric acid or dilute nitric acid, and the concentration is 0.1 mol / L; the time for ultrasonic treatment of nickel foam using dilute acid solution, anhydrous ethanol and deionized water is 10-30 minutes; In step 2, the nickel source is nickel nitrate hexahydrate, the molybdenum source is ammonium molybdate tetrahydrate, the chromium source is chromium chloride hexahydrate, and the molar mass ratio of the nickel source: molybdenum source: chromium source is 40:10:1 to 40:10:5; the temperature of the hydrothermal reaction is 150° C., the reaction time is 5-10 h, and the pseudocapacitance of the chromium-doped nickel molybdate anode material is 9.53 farads per square centimeter.

2. The use of a chromium-doped nickel molybdate pseudocapacitor anode material as claimed in claim 1, characterized in that: The cyclic voltammetry curve was tested using a three-electrode system, wherein the chromium-doped nickel molybdate anode material was used as a working electrode, a carbon rod was used as a counter electrode, a Hg / HgO electrode was used as a reference electrode, and a 1 mol potassium hydroxide solution was used as an electrolyte solution.

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