TWI827297B - Electrode material, preparation method of electrode and its application in supercapacitors - Google Patents

Abstract

An electrode material, a preparation method of the electrode and its application in supercapacitors are provided, wherein the preparation method of the electrode includes the following steps. An electrode support is provided. The electrode support is placed in a plating solution. An electroplating process is performed to form an electrode material on the electrode support. The electroplating solution includes a vanadium metal precursor and a nickel metal precursor, and the electrode material includes nickel-doped vanadium pentoxide.

Description

Electrode materials, electrode preparation methods and their applications in supercapacitors

The present invention relates to an electrode material, and in particular to a nickel-doped vanadium pentoxide electrode material, an electrode preparation method and its application in a supercapacitor.

With the development of high-level industrialization, the demand for energy is increasing day by day. However, the greenhouse gas effect caused by the use of fossil fuels, thermal power generation, and natural gas power generation has caused the occurrence of extreme climate on the earth. In order to improve this environmental degradation problem, therefore The development of renewable energy has become increasingly important, among which electrochemical energy conversion is an important part of renewable energy. The main energy conversion components include batteries, supercapacitors and fuel cells. At present, converting a large number of gasoline-burning vehicles into rechargeable electric vehicles to reduce air pollution emissions is the main operation direction of international car manufacturers. Because lithium-ion batteries have high weight and energy density, lithium-ion batteries are currently the most popular choice for electric vehicles. The main key components of charging and discharging.

In current lithium-ion batteries, the positive electrode (cathode) can be divided into layered structure, spinel structure, olivine structure and other materials. After lithium cobalt, there are lithium manganese, lithium nickel, lithium nickel cobalt, and lithium nickel cobalt. Cathode materials such as manganese and lithium iron phosphate have emerged one after another. The negative electrode is mainly made of lithium metal, graphite, lithium titanate, silicon and other materials. Lithium-ion batteries are the main power source widely used in the industry. However, lithium-ion batteries still have issues such as safety, strict production environment requirements, the use of cobalt and nickel resource metals, high-temperature cathode manufacturing processes, the use of harmful solvents, and battery recycling.

The electrochemical theory of clean water emissions from fuel cells is also an important consideration in the development of environmentally friendly vehicles. However, the application of fuel cells in electric vehicles involves the production, transportation and storage of hydrogen, the establishment and safety considerations of hydrogen stations, and the use of precious metal catalysts. As well as cost issues, the above issues involve the overall energy policy. Currently, there are only field demonstrations and no specific implementation.

Supercapacitors traditionally use the principle of electric double-layer capacitors. This supercapacitor has fast charge and discharge capabilities, so it is an important device for energy storage. It can store energy generated by green energy and provide backup power to prevent power outages. The current commercial product of this device has an energy density of only ~10 Wh/Kg, which is far lower than commercial lithium-ion batteries (120-150 Wh/Kg). It cannot be used for long distances or for long periods of time, and has the trouble of continuous charging. However, it has instantaneous Advantages of releasing large energy. If the energy density and specific capacity of supercapacitors can be improved to meet the requirements of lithium-ion batteries, fast-charging battery capacitors will have the opportunity to have a more ideal energy-saving combination with lithium-ion batteries and be used in industrial applications of electric vehicles and energy storage devices.

Currently, the electric double-layer capacitor electrodes of supercapacitors and the electrodes with Faradaic charge transfer capabilities in batteries are combined to construct hybrid, symmetric and asymmetric supercapacitor batteries, most of which are called hybrid supercapacitors. Supercapacitors have the ability to charge and discharge quickly and lithium-ion batteries have high energy density, thereby improving the energy density and specific capacity of supercapacitors and trying to improve the time-consuming charging of lithium-ion batteries. Electrodes with Faraday behavior are mainly transition metal oxides and transition metal hydroxides containing Ni, Fe, Co, Ti, Mo, V, Zn, and Nb. Important electrode materials include ruthenium dioxide (RuO ₂ ), Manganese (MnO ₂ ), spinel structure Co ₃ O ₄ , NiCo ₂ O ₄ and MnCo ₂ O ₄ , nickel oxide (NiO), nickel hydroxide (Ni(OH) ₂ ), vanadium pentoxide (V ₂ O ₅ ), etc., there are also composite materials composed of these materials and carbon-based materials as electrodes, which are mainly used for positive electrodes. There are also some oxides such as α-Fe ₂ O ₃ , Fe ₃ O ₄ , Bi ₂ WO ₆ , MoO _2, etc., which are mainly used in the negative electrode (ie, anode) of supercapacitors. At present, the highest energy density of CSO (Sn-Co ₃ O ₄ )@GF (i.e. graphene film)//Fe ₂ O ₃ @GF hybrid supercapacitor is 62.6 Wh/Kg; Co-Ni hydroxide/GO// Modified CC has a specific capacitance of 194 F/g at 10A/g and an energy density of 92 Wh/kg at a power density of 1400 W/kg; the three-dimensional V ₂ O ₅ /Pt/paper electrode uses colloidal electrolyte The capacitor enables it to have a charge and discharge capacity of 1V to 4V, a specific capacitance of 160 F/g at 1 A/g, and an energy density of 355 Wh/kg at a power density of 200 W/kg.

From the above, it can be seen that supercapacitors with high specific capacitance and high energy density have been reported in academic research one after another. However, this type of high-capacitance capacitor (i.e. supercapacitor) has the characteristics of instantaneous discharge of traditional supercapacitors, and has an open circuit state. Rapid self-discharge problem, so it cannot be used continuously. Therefore, developing new electrode materials to improve the problem of rapid and large-scale energy release in supercapacitors is an important goal of current development.

The invention provides an electrode material, an electrode preparation method and its application in a supercapacitor, which can effectively improve the problem of rapid and large-scale energy release by the supercapacitor, and has the advantages of simple manufacturing process and short manufacturing time.

The preparation method of the electrode according to the embodiment of the present invention includes the following steps. Provide electrode support materials. Place the electrode support material in the plating solution. An electroplating process is performed to form the electrode material on the electrode support material. The electroplating solution includes a vanadium metal precursor and a nickel metal precursor, and the electrode material includes nickel-doped vanadium pentoxide.

In an embodiment of the present invention, the above-mentioned electrode support material is foamed nickel.

In one embodiment of the present invention, the above-mentioned electrode support material includes foamed nickel and nickel hydroxide, and the nickel hydroxide is coated on the foamed nickel.

In one embodiment of the present invention, the above-mentioned step of coating nickel hydroxide on foamed nickel includes: placing the foamed nickel in a nitric acid bath with a molar concentration of 0.1, and soaking it at 80° C. for 4 hours.

In an embodiment of the present invention, the conditions of the electroplating process include: 1 minute to 10 minutes at a constant current of -10 mA.

In an embodiment of the present invention, the molar ratio of the above-mentioned vanadium metal precursor and nickel metal precursor is 1:1 to 1:4.

In an embodiment of the present invention, the above-mentioned electroplating solution further includes a third metal precursor, the electrode material includes nickel-doped and third metal-doped vanadium pentoxide, and the third metal is selected from manganese, cobalt, and iron. and potassium.

In one embodiment of the present invention, the content of the third metal precursor is 10% by weight based on the total weight of the above-mentioned vanadium precursor.

In an embodiment of the present invention, the above preparation method further includes the following steps. Before performing the electroplating process, the conductive material is placed on the electrode support material, so that after the electroplating process is performed, the conductive material is between the electrode material and the electrode support material; or after the electroplating process is performed, the conductive material is placed on On the electrode material, the electrode material is between the conductive material and the electrode support material. The conductive material is nanosilver or graphene.

The electrode material of the embodiment of the present invention includes nickel-doped vanadium pentoxide.

In an embodiment of the present invention, the above-mentioned electrode material includes nickel-doped and third metal-doped vanadium pentoxide. The third metal is selected from one of manganese, cobalt, iron and potassium.

The supercapacitor according to the embodiment of the present invention includes an anode, a cathode and an electrolyte. The cathode includes an electrode formed by the above-mentioned preparation method or an electrode material as above-mentioned. The anode is disposed relative to the cathode, and the anode includes the same electrode as the cathode or activated carbon-coated carbon cloth. The electrolyte is filled between the anode and cathode. Electrolytes include alkaline electrolytes or colloidal electrolytes. Colloidal electrolyte includes polyvinyl alcohol polymer and alkaline electrolyte.

Based on the above, the present invention uses an electroplating process with application advantages such as simple process, short process time, low energy consumption and clean process to prepare electrodes containing nickel-doped vanadium pentoxide electrode materials, and can be used in supercapacitors with high It has the advantages of specific capacitance, high energy density, low self-discharge rate and maintaining 90% performance after multiple charge and discharge cycles. The supercapacitor can not only increase the capacity of energy storage, but also has the characteristics of a fast-charging battery and has a better cycle life, and can effectively improve the problem of rapid and large-scale release of energy.

In order to make the above-mentioned features and advantages of the present invention more obvious and easy to understand, embodiments are given below and described in detail with reference to the accompanying drawings.

The present invention will be described more fully with reference to the drawings of this embodiment. However, the present invention may also be embodied in various forms and should not be limited to the embodiments described herein. The thickness of layers and regions in the drawings are exaggerated for clarity. The same or similar reference numbers indicate the same or similar components, and will not be repeated one by one in the following paragraphs.

It will be understood that when an element is referred to as being "on" or "connected to" another element, it can be directly on or connected to the other element or intervening elements may also be present. When an element is referred to as being "directly on" or "directly connected to" another element, there are no intervening elements present. As used herein, "connection" may refer to a physical and/or electrical connection, and "electrical connection" or "coupling" may refer to the presence of other components between two components.

As used herein, "about," "approximately" or "substantially" includes the recited value and the average within an acceptable range of deviations from the specific value that a person with ordinary skill in the art can determine, taking into account the Discuss the measurement and the specific amount of error associated with the measurement (i.e., the limitations of the measurement system). For example, "about" may mean within one or more standard deviations of the stated value, or within ±30%, ±20%, ±10%, ±5%. Furthermore, "about", "approximately" or "substantially" used in this article can be used to select a more acceptable deviation range or standard deviation based on optical properties, etching properties or other properties, and one standard deviation does not apply to all properties. .

The terminology used herein is used only to describe illustrative embodiments and does not limit the disclosure. In such cases, the singular form includes the plural form unless the context dictates otherwise.

In the present invention, the electrode preparation method includes the following steps. First, an electrode support material is provided. Next, the electrode support material is placed in the plating solution. Then, an electroplating process is performed to form the electrode material on the electrode support material. The electroplating solution in the embodiment of the present invention may include a vanadium metal precursor and a nickel metal precursor, and the electrode material may include nickel-doped vanadium pentoxide (V ₃ O ₅ ).

In some embodiments, the electrode support material may be, for example, porous nickel foam (Ni Foam, NF). Specifically, the foamed nickel can be cleaned first and then dried for use. The specific steps can be, for example (but are not limited to): cleaning the foamed nickel with deionized water, ethanol and acetone in sequence, and then drying it at 60°C. 2 hours. In this article, the code name of the obtained foamed nickel is NF.

In other embodiments, the electrode support material may include, for example, foamed nickel and nickel hydroxide (Ni(OH) ₂ ), and the nickel hydroxide is coated on the foamed nickel. Specifically, the step of coating nickel hydroxide on the surface of foamed nickel may be, for example (but not limited to): placing the cleaned foamed nickel into a nitric acid bath with a molar concentration (M) of 0.1, and then heating to 80 ℃ and soak for 4 hours. Then, place it in an oven at 60°C for 2 hours to dry and set aside. In this article, when the electrode support material uses foamed nickel with nickel hydroxide coating, it is expressed as Ni(OH) ₂ .

In some embodiments, the molar ratio of the vanadium metal precursor to the nickel metal precursor in the electroplating solution may be, for example, 1:1 to 1:4. In some preferred embodiments, the molar ratio of the vanadium metal precursor to the nickel metal precursor may be 1:1 or 1:4. In some more preferred embodiments, the molar ratio of the vanadium metal precursor to the nickel metal precursor may be 1:1. When the ratio of the vanadium metal precursor to the nickel metal precursor is within the range defined above, the formed electrode material can have the advantages of high specific capacitance value and high energy density.

In some embodiments, the plating solution may include a vanadium metal precursor, a nickel metal precursor, and a third metal precursor. Specifically, the third metal may be, for example, one selected from the group consisting of manganese, cobalt, iron, and potassium. That is, the third metal precursor may be, for example, selected from the group consisting of manganese metal precursor, cobalt metal precursor, and cobalt metal precursor. material and potassium metal precursor. The electrode material may include nickel-doped and third metal-doped vanadium pentoxide (ie, vanadium pentoxide doped with nickel and a third metal at the same time). Here, based on the total weight of the vanadium precursors in the electroplating solution, the content of the third metal precursor may be, for example, 10% by weight, but is not limited to this.

In more detail, in some preferred embodiments, when the third metal is cobalt or iron, the formed electrode material can have the advantages of high specific capacitance value and high energy density.

In some embodiments, the conditions of the electroplating process may include (but are not limited to): performing cathodic deposition at a constant current of -10 amperes (mA) for 1 to 10 minutes, with 3 M potassium chloride (KCl) solution was used as the electrolyte, Pt foil was used as the counter electrode and Ag/AgCl was used as the reference electrode.

In some embodiments, the conductive material can be disposed on the electrode support material before performing the electroplating process. In this way, after the subsequent electroplating process, the formed electrode material is coated on the conductive material and does not contact the electrode support material. That is, the conductive material is interposed between the electrode material and the electrode support material. In some other embodiments, after performing the electroplating process, the conductive material can be disposed on the electrode material, so that the electrode material is between the conductive material and the electrode support material. In the present invention, the conductive material can be, for example, nanosilver (Ag) or graphene (graphene), but is not limited thereto.

In embodiments of the present invention, supercapacitors can be prepared by electrodes having the above-mentioned electrode materials. Specifically, a supercapacitor includes a cathode (positive electrode), an anode (negative electrode), and an electrolyte. The cathode includes an electrode formed by the above-mentioned preparation method or an electrode material as above-mentioned. The anode is disposed relative to the cathode, and the anode includes the same electrode as the cathode or activated carbon-coated carbon cloth. When the cathode and anode have the same electrodes, the supercapacitor at this time can be called a symmetrical supercapacitor. When the anode and cathode have different electrodes, the supercapacitor at this time can be called an asymmetric supercapacitor.

The electrolyte is filled between the anode and cathode. Electrolytes include alkaline electrolytes (such as 3 M KOH) or colloidal electrolytes. The colloidal electrolyte includes polyvinyl alcohol (PVA) polymer and alkaline electrolyte. That is, in this embodiment, the colloidal electrolyte can be obtained by mixing PVA polymer into the alkaline electrolyte, but this is not the case. limit.

In the present invention, an electrode containing nickel-doped vanadium pentoxide electrode material is prepared through an electroplating process with application advantages such as simple process, short process time, low energy consumption and clean process, and can be used in supercapacitors with high It has the advantages of specific capacitance, high energy density, low self-discharge rate and maintaining 90% performance after multiple charge and discharge cycles. The supercapacitor can not only increase the capacity of energy storage, but also has the characteristics of a fast-charging battery and has a better cycle life, and can effectively improve the problem of rapid and large-scale release of energy.

The characteristics of the modified vanadium-based electrode of the present invention (in the present invention, nickel-doped vanadium pentoxide) will be described in more detail below through experimental examples. Although the following experimental examples are described, the materials used, their amounts and ratios, processing details, processing procedures, and the like may be appropriately changed without exceeding the scope of the present invention. Therefore, the present invention should not be interpreted restrictively by the experimental examples described below. ＜ Experimental example ＞

In the present invention, the electrode support material is made of porous foamed nickel (Ni Foam, NF), and is cleaned in the following two processes: the first is washed with DI water, ethanol and acetone in sequence, and then dried at 60 ^o C 2 hours, the code name of the foamed nickel obtained is NF. The second step is the hot acid treatment step: place the foamed nickel in a 0.1 M nitric acid bath, heat it at 80 ^o C/4 h, wash it and dry it in an oven at 60 ^o C for 2 hours. The obtained foamed nickel is Ni( OH) ₂ is coated on NF, and the code is represented by Ni(OH) ₂ .

Next, electroplating deposition is performed on the electrode support material (i.e., NF or Ni(OH) ₂ ) under different conditions described in the <Experimental Procedures> below to complete the preparation of the supercapacitor positive electrode.

The obtained electrode was used to measure the half-cell characteristics using three-pole electrochemistry. The experimentally developed and adopted material was used as the working electrode, the saturated Hg/HgO electrode was used as the reference electrode, and the Pt sheet was used as the counter electrode. When measuring two-pole full cells, for the manufacture of asymmetric supercapacitors, the cathode is made of the developed material, and the anode is made of activated carbon-coated carbon cloth or the modified transition metal oxide developed by this institute is also used as the electrode material. Form a symmetrical supercapacitor. Between the anode and the cathode, add a filter paper isolation membrane, fill in 3 M KOH alkali solution to form an alkali electrolyte, or mix polyvinyl alcohol (PVA) polymer into the alkali solution to form a colloidal electrolyte. Full-battery supercapacitors are mainly characterized by charge-discharge GCD technology. ＜ Experimental Procedure ＞

1.1 The preparation of vanadium modified transition metal oxide electrode materials on foamed nickel is completed by electroplating. A typical experiment is used to illustrate the experimental process. Vanadium and a second metal (for example, nickel (Ni)) precursor are mixed in a beaker with a total capacity of 100 mL at a molar ratio of 1:1 (expressed as VN-1). Then, cathodic deposition of VN-1 (expressed as NV-1/NF) on the foamed nickel electrode support material was performed using a three-pole system (SP-300, BioLogic) at a constant current of -10 mA with 3 M KCl Solution electrolyte, Pt foil as counter electrode and Ag/AgCl as reference electrode. After plating for 1 to 10 minutes, NV-1/NF is dried at 60 ^° C for 1 hour. Finally, the sample was gravimetrically analyzed by a precision analytical balance to determine the mass of VN-1 deposited on the electrode support material. The mass of VN-1 was 2.3 ± 0.8 mg. The support material is soaked in hot acid to form a Ni(OH) ₂ phase on the foamed nickel, and NV-1 is coated (ie, electroplated) on the foamed nickel. The resulting electrode is Ni(OH) ₂ /VN-1. Using the NF support material and the nickel metal precursor at 150 ^o C for a pressure kettle hydrothermal process, NF/NiO can be obtained, and then the electroplating process is performed, and the resulting electrode is NiO/VN-1. If 2-methylimidazole is added to the reaction tank, VN-MOF can be obtained.

1.2 Different nickel precursor concentrations are matched with vanadium. The molar ratios of vanadium metal precursor and nickel precursor include 1:2, 1:3, and 1:4, then VN-2 and VN-3 are formed in sequence. , VN-4.

1.3 Use foamed NiFe and NiMo to grow VN-1 to obtain NiFe foam/VN-1 and NiMo foam/VN-1.

1.4 Place conductive materials such as silver nanoparticles (Ag) and graphene between foamed nickel and VN-1 to obtain Ni(OH) ₂ /Ag/VN-1 and Ni(OH) ₂ /graphene/VN -1; or place a conductive material on the surface of VN-1 to obtain Ni(OH) ₂ /VN-1/graphene.

1.5 If 10% of the third metal precursor is added to the electroplating reaction tank, such as Mn, Co, Fe, and K, VN-1+10% Mn, VN-1+10% Co, and VN-1+10 can be obtained respectively. % Fe, VN-1+10% K.

1.6 When selecting the type of electrolyte, 3M KOH, 3M LiOH and 3M NaOH are also used for comparison of alkaline electrolytes. ＜ Experimental results ＞

Figures 1A to 1C show the vanadium-based modified doped transition metal oxide VN-1 (Figure 1A), Ni(OH) ₂ (Figure 1B), Ni(OH) ₂ /VN-1 (Figure 1C) Yu Fa Scanning electron microscope image of electrode material on nickel foam.

In this experimental example, the prepared electrode material of vanadium modified transition metal oxide VN-1, Ni(OH) ₂ , Ni(OH) ₂ /VN-1 on foamed nickel, the scanning electron microscope The images are shown in Figure 1A, Figure 1B, and Figure 1C. When VN-1 with an irregular network structure is coated on the nickel hydroxide with a sheet structure, the smooth sheet structure is covered with a network to make the surface uneven. Smooth again.

Figure 2 shows the XRD diffraction pattern of VN-1 plated from vanadium-nickel precursor (the molar ratio of vanadium to nickel is 1:1).

Please refer to Figure 2. There are strong characteristic peaks of nickel metal at 2θ of 45 and 52 degrees. This signal originates from foamed nickel and does not belong to the surface-covered doped vanadium oxide film; in addition, at 2θ of 29 There are also strong diffraction signals at , 47.2 and 48.6 degrees. After comparison, it is determined that the signal originates from vanadium pentoxide (V ₃ O ₅ ), and its diffraction crystal planes are (-303) and (-305) respectively. and (-123).

Figure 3 shows the XRD diffraction patterns of Ni(OH) ₂ and Ni(OH) ₂ /VN-1.

Please refer to Figure 3. The diffraction peaks of the bottom layer Ni(OH) ₂ are consistent with the peak positions of nickel hydroxide in the standard chart. They are located at 2θ of 18.58, 32.4 and 37.78 degrees, and the diffraction crystal planes are ( 001), (100) and (101), indicating that the template used for VN-1 deposition is indeed nickel hydroxide. In addition, although the diffraction pattern of Ni(OH) ₂ /VN-1 has the characteristic peak of Ni(OH) ₂ , the signal intensity is relatively weak.

Figure 4 shows the charge-discharge (GCD) curves of Ni(OH) ₂ /VN-1 electrode material and its half-cell in 3 M KOH electrolyte under different current conditions.

Please refer to Figure 4. The Ni(OH) ₂ /VN-1 electrode material has a specific capacitance value of 7500 F/g at a rate of 1 A/g, as shown in Table 1. VN-1 was grown by direct electroplating of unpickled foamed nickel, and its specific capacitance value also reached 5528 F/g. Table 1 also lists the specific capacitance values of different modified vanadium electrode materials, mainly Ni(OH) ₂ /VN-1, modified by graphene or silver, or adding a third metal precursor. Most of them have specific capacitance values of more than 4000 F/g.

Table 1. Half-cell characteristics of vanadium pentoxide obtained with different modifications, different composition formulas, and different process conditions Electrode material sample Specific capacitance (Capacitance) Energy density Power density (at a current density of 1 A/g) (F/g) (W*h/kg) (W/kg) VN-1 in 3M KOH 5529 122 213 VN-1 in 3M LiOH 1779 38 198 VN-1 in 3M NaOH 2300 49 210 Ni(OH) ₂ /VN-1 7500 166 204 Ni(OH) ₂ /VN-1/graphene 6700 134 185 NiFe foam/VN-1 384 7.7 191 NiMo foam/VN-1 3910 82.59 195 VN-1 + 10% Mn 3602 58 168 VN-1 + 10%Co 4212 89 194 VN-1+10% Fe 4712 100 196 VN-1 + 10% K 884 19 204 NiO(hydrothermal)/VN-1 2761 58 193 VN-1/MOF 106 2.85 216 Ni(OH) ₂ /graphene/VN-1 6371 135 200 Ni(OH) ₂ /Ag/VN-1 4641 98 197 VN-2 1709 43.8 215 VN-3 1479 38 214 VN-4 4140 92 201

Figure 5 shows the charge and discharge (GCD) curves of the asymmetric supercapacitor AC//Ni(OH) ₂ /VN-1 assembled with activated carbon in 3 M KOH alkaline electrolyte under different current conditions. Figure 6 shows the charge and discharge (GCD) curves of the symmetrical supercapacitor Ni(OH) ₂ /VN-1//Ni(OH) ₂ /VN-1 in 3 M KOH alkaline electrolyte under different current conditions. . Figure 7 shows the charge and discharge (GCD) curves of the symmetrical supercapacitor Ni(OH) ₂ /VN-1//Ni(OH) ₂ /VN-1 in KOH-PVA colloidal electrolyte under different current conditions.

In this experimental example, the supercapacitor is an asymmetric supercapacitor AC//Ni(OH) ₂ /VN-1 that uses Ni(OH) ₂ /VN-1 electrode material as the main body and is assembled with activated carbon. It is in 3M KOH Under alkaline electrolyte, the GCD measurement results are shown in Figure 5, and the data are listed in Table 2. The GCD measurement results of the asymmetric supercapacitor AC//Ni(OH) ₂ /VN-1 under KOH-PVA colloidal electrolyte are listed in Table 3. Symmetrical supercapacitor Ni( _OH ) ₂ /VN-1//Ni(OH) ₂ /VN-1 assembled from modified vanadium-based Ni(OH) 2 /VN-1 electrode material itself, alkaline in 3 M KOH Under electrolyte solution, the GCD measurement results are shown in Figure 6, and the data are listed in Table 4. The GCD measurement results of the symmetrical supercapacitor Ni(OH) ₂ /VN-1//Ni(OH) ₂ /VN-1 in KOH-PVA colloidal electrolyte are shown in Figure 7, and the data are listed in Table 5.

Table 2. Various data of asymmetric AC//Ni(OH) ₂ /VN-1 alkali solution (3M KOH) supercapacitor Current density Specific capacitance (Capacitance) Energy density Power density A/g (F/g) (W*h/kg) (W/kg) 1 512 193 825 3 225 85 2475 5 145 55 4125 10 55 twenty one 8250 20 19 7 16500

Table 3. Various data of asymmetric AC//Ni(OH) ₂ /VN-1 colloidal supercapacitor Current density Specific capacitance (Capacitance) Energy density Power density A/g (F/g) (W*h/kg) (W/kg) 1 390 286 1150 3 137 100 3428 5 75 55 5740 10 10 7.5 11740

Table 4. Various data of symmetric Ni(OH) ₂ /VN-1//Ni(OH) ₂ /VN-1 alkali solution (3M KOH) supercapacitor Current density Specific capacitance (Capacitance) Energy density Power density A/g (F/g) (W*h/kg) (W/kg) 1 1481 296 600 3 1000 200 1800 5 708 141 2985 10 466 93.2 5991 20 166 33.2 11952

Table 5. Various data of symmetric Ni(OH) ₂ /VN-1//Ni(OH) ₂ /VN-1 colloidal supercapacitor Current density Specific capacitance (Capacitance) Energy density Power density A/g (F/g) (W*h/kg) (W/kg) 1 846 170 602 3 520 104 1800 5 270.8 54.2 3000 10 166.6 33.2 8537

Under KOH alkali solution and colloidal electrolyte, the asymmetric supercapacitor assembled by the modified vanadium-based Ni(OH) ₂ /VN-1 electrode material itself has the best specific capacitance under the condition of 1 A/g current density. The values are 512 and 390 F/g, the energy density is 193 and 286 Wh/Kg, and the power density is 825 and 1150 W/Kg.

Under KOH alkali solution and colloidal electrolyte, the best performing modified vanadium-based Ni(OH) ₂ /VN-1 electrode material is a symmetrical supercapacitor assembled by itself. At a current density of 1 A/g, its specific capacitance value is They are 1481 and 846 F/g respectively, the energy density is 296 and 170 Wh/Kg, and the power density is 600 and 602 W/Kg.

Figure 8A and Figure 8B show the cyclic tests of different colloidal supercapacitors: asymmetrical AC//Ni(OH) ₂ /VN-1 (Figure 8A), symmetrical Ni(OH) ₂ /VN-1//Ni( OH) ₂ /VN-1 (Fig. 8B).

The colloidal supercapacitor was tested for cycle stability and discussed. The current density was fixed at 40 A/g and the number of cycles was 10,000 times. Figure 8A and Figure 8B show the cycle test of the colloidal supercapacitor. It can be found from the figure that the asymmetry AC//Ni(OH) ₂ /VN-1 (Figure 8A) and the symmetry Ni(OH) ₂ /VN-1//Ni(OH) ₂ /VN-1 (Figure 8A 8B) After 10,000 cycles of the colloidal supercapacitor, the Coulombic efficiency still remains 100%, indicating that the two components can still completely desorb the adsorbed ions under long-term reaction, and the material interface does not produce passivation or no Electrolytes decompose. In addition, after 10,000 cycles, the asymmetric AC//Ni(OH) ₂ /VN-1 and symmetric Ni(OH) ₂ /VN-1//Ni(OH) ₂ /VN-1 colloidal supercapacitors have The capacitance retention rates are 97% and 95% respectively.

Figure 9 shows the decline of the open circuit voltage over time of the Ni(OH) ₂ /VN-1 supercapacitor developed in the embodiment of the present invention.

Please refer to Figure 9. After 60 hours, the decay rate is about 50%. Compared with current academic research and development literature reports, the self-discharge of supercapacitors with high specific capacitance values drops to close to 0 V in almost 5 minutes. Although the self-discharge performance of the embodiments of the present invention is not as good as that of carbon-based supercapacitors, But it is different from traditional supercapacitors.

Figure 10 shows the comparative differences in LED discharge behavior between Ni(OH) ₂ /VN-1 supercapacitor (1.0 x 1.5 cm) and commercially available 2.7V/7F and 2.7V/100F supercapacitors.

In order to show that the vanadium-based supercapacitor of the present invention is different from traditional supercapacitors, LED is used as the load for comparison. Figure 10 shows the comparison between the Ni(OH) ₂ /VN-1 (1.0 x 1.5 cm) supercapacitor developed in the embodiment of the present invention and the commercially available 2.7V/7F and 2.7V/100F supercapacitors on light-emitting diodes (LEDs). Contrasting differences in discharge behavior. The specific capacitance values of 2.7V/7F, 2.7V/100F and Ni(OH) ₂ /VN-1 are 30, 90 and 430 mAh respectively; the energy densities are 44, 120 and 240 mWh respectively. Since the size of commercially available 2.7V/100F supercapacitors is very large, compared with Ni(OH) ₂ /VN-1, it can be found that Ni(OH) ₂ /VN-1 is a combination of traditional supercapacitors and battery behaviors.

To sum up, the present invention proposes an electrochemical plating method with application advantages such as simple process, short process time, low energy consumption and clean process to prepare modified vanadium-based metal oxide (ie, nickel-doped vanadium pentoxide). On the electrode support material (i.e., foamed nickel or nickel hydroxide-coated foamed nickel), and can be used as an electrode of a supercapacitor, with high specific capacitance, high energy density, low self-discharge rate and multiple charge-discharge cycles still maintains good performance.

In addition, the cobalt-based oxide electrode material is mainly nickel-doped vanadium pentoxide (V ₃ O ₅ ). This electrode material has a specific capacitance in an alkaline electrolyte under a current density of 1 A/g. The specific capacitance reaches 5529 F/g; if this electroplating process is applied to a substrate that uses hot acid treatment to form Ni(OH) ₂ /foamed nickel, the specific capacitance reaches 7500 F/g. Add polymers to the alkaline electrolyte to form a colloidal electrolyte, and combine it with the activated carbon negative electrode to form an asymmetric colloidal supercapacitor. This supercapacitor has a high specific capacitance of 390 F/g and a high energy density of 286 at 1 A/g. Wh/Kg, low self-discharge rate (50% reduction in 60 hours) and 10,000 cycle performance still maintain 90%. It is obvious from the above that this supercapacitor not only improves the energy storage capacity, but also has the characteristics of a fast-charging battery and has a better cycle life. The most important thing is to improve the problem of rapid and large-scale energy release of traditional supercapacitors.

Although the present invention has been disclosed above through embodiments, they are not intended to limit the present invention. Anyone with ordinary knowledge in the technical field may make some modifications and modifications without departing from the spirit and scope of the present invention. Therefore, The protection scope of the present invention shall be determined by the appended patent application scope.

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Figures 1A to 1C show the vanadium-based modified doped transition metal oxide VN-1 (Figure 1A), Ni(OH) ₂ (Figure 1B), Ni(OH) ₂ /VN-1 (Figure 1C) Yu Fa Scanning electron microscope image of electrode material on nickel foam. Figure 2 shows the XRD diffraction pattern of VN-1 plated from vanadium-nickel precursor (the molar ratio of vanadium to nickel is 1:1). Figure 3 shows the XRD diffraction patterns of Ni(OH) ₂ and Ni(OH) ₂ /VN-1. Figure 4 shows the charge-discharge (GCD) curves of Ni(OH)2/VN-1 electrode material and its half-cell in 3 M KOH electrolyte under different current conditions. Figure 5 shows the charge and discharge (GCD) curves of the asymmetric supercapacitor AC//Ni(OH) ₂ /VN-1 assembled with activated carbon in 3 M KOH alkaline electrolyte under different current conditions. Figure 6 shows the charge and discharge (GCD) curves of the symmetrical supercapacitor Ni(OH) ₂ /VN-1//Ni(OH) ₂ /VN-1 in 3 M KOH alkaline electrolyte under different current conditions. . Figure 7 shows the charge and discharge (GCD) curves of the symmetrical supercapacitor Ni(OH) ₂ /VN-1//Ni(OH) ₂ /VN-1 in KOH-PVA colloidal electrolyte under different current conditions. Figure 8A and Figure 8B show the cyclic tests of different colloidal supercapacitors: asymmetrical AC//Ni(OH) ₂ /VN-1 (Figure 8A), symmetrical Ni(OH) ₂ /VN-1//Ni( OH) ₂ /VN-1 (Fig. 8B). Figure 9 shows the decline of the open circuit voltage of the Ni(OH) ₂ /VN-1 supercapacitor over time. Figure 10 shows the comparative differences in LED discharge behavior between Ni(OH) ₂ /VN-1 supercapacitor (1.0 x 1.5 cm) and commercially available 2.7V/7F and 2.7V/100F supercapacitors.

Claims (12)

A method of preparing an electrode, including: providing an electrode support material; placing the electrode support material in an electroplating solution; and performing an electroplating process to form an electrode material on the electrode support material, wherein the electroplating solution includes vanadium metal The precursor is a nickel metal precursor, and the electrode material includes nickel-doped vanadium pentoxide. The preparation method according to claim 1, wherein the electrode support material is foamed nickel. The preparation method according to claim 1, wherein the electrode support material includes foamed nickel and nickel hydroxide, and the nickel hydroxide is coated on the foamed nickel. The preparation method according to claim 3, wherein the step of coating the nickel hydroxide on the foamed nickel includes: placing the foamed nickel in a nitric acid bath with a molar concentration of 0.1, and incubating the foamed nickel at 80 Soak for 4 hours at ℃. The preparation method according to claim 1, wherein the conditions of the electroplating process include: 1 minute to 10 minutes at a constant current of -10 mA. The preparation method according to claim 1, wherein the molar ratio of the vanadium metal precursor to the nickel metal precursor is 1:1 to 1:4. The preparation method of claim 1, wherein the electroplating solution further includes a third metal precursor, the electrode material includes nickel-doped and third metal-doped vanadium pentoxide, and the third metal is selected from From one of manganese, cobalt, iron and potassium. The preparation method according to claim 7, wherein the content of the third metal precursor is 10% by weight based on the total weight of the vanadium metal precursor. The preparation method according to claim 1, further comprising: before performing the electroplating process, disposing a conductive material on the electrode support material, so that after the electroplating process is performed, the conductive material is between the between the electrode material and the electrode support material; or after performing the electroplating process, conductive material is disposed on the electrode material so that the electrode material is between the conductive material and the electrode support material , wherein the conductive material is nanosilver or graphene. An electrode material suitable for a cathode of a supercapacitor, wherein the electrode material includes nickel-doped vanadium pentoxide. The electrode material of claim 10, wherein the electrode material includes vanadium pentoxide doped with nickel and a third metal, and the third metal is selected from one of manganese, cobalt, iron, and potassium. A supercapacitor, including: a cathode, including an electrode formed by the preparation method as described in any one of claim 1 to claim 9 or an electrode material as described in claim 10 or claim 11; an anode, relative to the The cathode is arranged, and the anode includes the same electrode as the cathode or a carbon cloth covered with activated carbon; and an electrolyte is filled between the anode and the cathode, and the electrolyte includes an alkaline electrolyte or glue A state electrolyte, wherein the colloidal electrolyte includes polyvinyl alcohol polymer and the alkaline electrolyte.