A method for electrodepositing MnO on carbon fiber paper x Material preparation methods and construction of high-energy-density supercapacitors

Abstract

This invention discloses a method for electrodepositing MnO on carbon fiber paper. x The invention relates to a method for preparing materials and constructing high-energy-density supercapacitors. The method involves acid washing, chemical oxidation, and electrochemical activation of the carbon fiber paper surface followed by electrodeposition of MnO. x Electrodeposition of MnO on CFP x This invention provides a novel approach, demonstrating a significant improvement in electrochemical performance through test results, specifically electrodeposition. Furthermore, starting with decoupling the electrolyte system, this invention utilizes two different electrolyte types, Na₂SO₄ and NaOH, as the positive and negative electrode electrolytes respectively, along with an external cation separator, to successfully assemble a novel Mn / / Zn wide-voltage-window superelectric device. This device boasts a voltage window as high as 1.3–2.6 V, greatly enhancing the performance of MnO₂. x Energy density of a supercapacitor.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage, specifically relating to a method for electrodepositing MnO on carbon fiber paper. x Material preparation methods and construction of high-energy-density supercapacitors. Background Technology

[0002] With rapid economic development, there has been a huge demand for energy. The massive consumption of traditional non-renewable mineral energy sources such as coal, oil, and natural gas has led to numerous environmental problems and challenges in their sustainable use. Therefore, finding abundant renewable and clean energy sources is crucial for mitigating environmental pollution, improving the atmospheric environment, developing a low-carbon economy, and promoting sustainable development.

[0003] Supercapacitors have a series of advantages such as high specific power, fast charge and discharge rate, long cycle life, and environmental friendliness. However, compared with traditional batteries, their lower specific energy limits their practical application. To improve the energy density of supercapacitors, we can do so from the following two aspects: (1) increase the capacitance of the electrode material to improve the energy density of the device; (2) increase the operating voltage window of the device, according to the energy density formula. By increasing the voltage window of the device, the energy density of the supercapacitor can be increased.

[0004] MnO2 material is inexpensive, non-toxic, and has a variety of crystal forms. Due to its high theoretical specific capacity (1096 C / g), it is one of the key research areas for supercapacitor electrode materials. However, MnO2 has poor conductivity, so in actual tests, the actual specific capacity of MnO2 is far from its theoretical value. To improve the conductivity of MnO2, the most common methods are: (1) Combining it with carbon materials, utilizing the large specific surface area and good conductivity of carbon materials, and combining them with manganese dioxide to improve the conductivity of manganese dioxide and the electrochemical performance of the composite material; (2) Doping manganese dioxide with metal ions. Carbon composite is an important method to improve the performance of manganese dioxide electrode materials, which can improve the conductivity of manganese dioxide and its electrochemical performance; (3) Further optimizing the treatment of CFP and MnO through acid washing, KMnO4 oxidation and electrochemical activation. x The interface improves MnO x Electrochemical utilization rate. Interface treatment is very important for improving electrochemical performance.

[0005] Due to limitations imposed by the decomposition voltage and the operating voltage of the electrode materials, the voltage window of super devices is relatively low. Therefore, there are two main methods to improve the voltage window of the device: (1) improve the electrode materials to increase their voltage window; (2) change the electrolyte used to increase its decomposition voltage and use solid electrolytes, etc. However, neither of these methods is very effective in improving the voltage window of the device. Summary of the Invention

[0006] This invention addresses the shortcomings of the prior art by providing a method for electrodepositing MnO on carbon fiber paper. x Material preparation method and construction of high-energy-density supercapacitor. This invention involves acid washing, chemical oxidation, and electrochemical activation of the carbon fiber paper (CFP) surface followed by electrodeposition of MnO. x Electrodeposition of MnO on CFP x This invention provides a novel approach, demonstrating a significant improvement in electrochemical performance through test results. Furthermore, starting with decoupling the electrolyte system, this invention utilizes two different electrolytes, Na₂SO₄ and NaOH, as the positive and negative electrode electrolytes respectively, along with an external cation separator, to successfully assemble a novel Mn / / Zn wide-voltage-window superelectric device. This device boasts a voltage window as high as 1.3-2.6V, greatly enhancing the performance of MnO₂. x The energy density of supercapacitors. Only with such special electrolyte and electrode material systems can high-energy-density devices like Mn / / Zn system battery capacitors be assembled.

[0007] This invention relates to the electrodeposition of MnO on carbon fiber paper. x The preparation method of the material includes the following steps:

[0008] Step 1: Add CFP to a mixed solution of concentrated nitric acid and concentrated sulfuric acid in a volume ratio of 3:1, stir at 60-80℃ for 3-8 hours, rinse repeatedly with deionized water until neutral and dry. This improves the hydrophilicity of the material and makes it easier for it to bind with water molecules, thus improving the material's performance.

[0009] Step 2: Add 0.1-20g KMnO4 to 10-100mL of deionized water, stir to disperse evenly, and then add 2-10mL of 1M HCl solution. Add the hydrophilized CFP to the above solution and react fully for 12h. Then wash with deionized water, dry, weigh, and test to obtain CFP@MnO4. x -1, Preliminary growth of MnO on CFP x .

[0010] Step 3: Take the CFP@MnO obtained in Step 2 x-1 is subjected to an electrochemical activation cycle (CD cycle), then washed with 30% H2O2 solution, followed by washing with deionized water and drying, to allow CFP@MnO to be processed. x -1. Residual manganese-based oxides in the material must be completely removed. Interface treatment is crucial for improving electrochemical performance.

[0011] Step 4: Place the material obtained in Step 3 into the electrodeposition solution for constant current electrodeposition. After deposition, wash with deionized water and dry to obtain electrodeposited MnO on CFP. x , denoted as CFP@MnO x The final electrode material is obtained.

[0012] In step 3, the electrolyte used in the electrochemical activation cycle treatment is 0.1M-3M Na2SO4 electrolyte, with CD cycles ≥5000 times and current density ≥5A / g.

[0013] In step 4, the electrodeposition solution is a mixture of 0.01M-1M Mn(CH3COO)2 and 0.01M-1M Na2SO4, and the constant current electrodeposition time is 50-600 s, using 10-400 mA cm⁻¹. -2 Deposition is performed using a specific current density. Different deposition times can yield deposited materials with varying loads.

[0014] Further optimization: The electrodeposition solution was a mixture of 0.06 M Mn(CH3COO)2 and 0.06 M Na2SO4, the constant current electrodeposition time was 300 s, and a 40 mA cm⁻¹ electrodeposition temperature was used. -2 Deposition was performed using a current density of 1 × 1 cm. 2 .

[0015] CFP@MnO prepared using the present invention x Materials are used to construct high specific energy devices.

[0016] Specifically, it is based on the aforementioned CFP@MnO x Using Zn foil as the negative electrode material and Na2SO4 and NaOH as the positive and negative electrolytes respectively, along with an external cation exchange membrane, a novel supercapacitor with a wide voltage window was assembled. The voltage window can reach 1.3-2.6V, significantly improving the energy density of the supercapacitor, and these devices are also easily portable.

[0017] The beneficial effects of this invention are reflected in:

[0018] 1. The raw materials used are readily available, non-toxic and harmless, and have low requirements for instruments and equipment, and are easy to operate.

[0019] 2. This invention utilizes an interface modification strategy to electrodeposit MnO on a CFP.x Electrode materials have significantly improved their specific capacity, increasing their applications in the field of electrochemistry.

[0020] 3. The present invention synthesizes materials with high specific capacitance, expands the voltage window of the device, thereby greatly improving the energy density of the supercapacitor and providing a certain possibility for the practical application and commercial development of supercapacitors in the future.

[0021] 4. The method for constructing the wide voltage window superelectric device of the present invention can be applied in a variety of material systems. The negative electrode uses Zn foil and there is no need to adjust the load ratio of different positive and negative electrode materials. By selecting appropriate positive and negative electrode electrolytes, the wide voltage window device can be constructed.

[0022] 5. The method for constructing the novel wide-voltage window superelectric device of the present invention uses Na2SO4 as the positive electrode for CFP@MnO. x The electrolyte is NaOH, which is used as the electrolyte for the Zn foil at the negative electrode. The cation exchange membrane contains only Na+ ions. + Conduction occurs because the negatively charged groups in the cation exchange membrane used repel Zn(OH)4. 2- Transmembrane transport prevents Zn dendrite growth across the membrane, eliminating the performance and safety hazards posed by Zn dendrites to devices. Attached Figure Description

[0023] Figure 1 These are SEM images of a hydrophilically treated CFP at different magnifications. (a) and (b) represent different magnifications, respectively.

[0024] Figure 2 It is CFP@MnO x -1 SEM images of the electrode material at different magnifications. Where (a) and (b) are different magnifications.

[0025] Figure 3 CFP@MnO treated with H2O2 x SEM images of -1. Where (a) and (b) represent different magnifications.

[0026] Figure 4 It is CFP@MnO x SEM images of the electrode material at different magnifications. (a) and (b) represent different magnifications.

[0027] Figure 5 It is CFP@MnO x TEM images of the electrode material under a transmission electron microscope. (a) and (b) represent different magnifications.

[0028] Figure 6 It is CFP@MnO x EDS image of the electrode material under a transmission electron microscope.

[0029] Figure 7 It is CFP@MnO x TEM (a) and corresponding SAED image (b) of the electrode material under a transmission electron microscope.

[0030] Figure 8 Electrodeposited MnO on CFP x XRD pattern of electrode material.

[0031] Figure 9 Electrochemical performance of the electrode material directly grown in CFP using KMnO4 in a three-electrode system: (a) CV curve; (b) CD curve; (c) specific capacity at different current densities.

[0032] Figure 10 CFP@MnO treated with H2O2 x Electrochemical performance of -1 in a three-electrode system: (a) CV curve; (b) CD curve; (c) specific capacity at different current densities.

[0033] Figure 11 It is CFP@MnO x Electrochemical performance of electrode materials in a three-electrode system: (a) CV curve; (b) CD curve; (c) specific capacity at different current densities; (d) cycle performance.

[0034] Figure 12 Electrodeposited MnO on CFP x Electrochemical performance of electrode materials at different windows in a three-electrode system: (a) Comparison of CD curves at a current density of 1 A / g; (b) Comparison of specific capacity at different current densities.

[0035] Figure 13 Electrodeposited MnO on CFP x High load on electrode materials: (a) CV curve; (b) CD curve; (c) Specific capacitance at different current densities.

[0036] Figure 14 Electrochemical performance of the assembled dual-slot wide voltage window device: (a) CV curve; (b) CD curve; (c) specific capacitance at different current densities; (d) cycling performance; (e) Ragone plot.

[0037] Figure 15 Assembled wide voltage window glued flexible packaged device: (a) Display of the complete device; (b) Regarding the positive electrode CFP@MnO x(c) Side view of the flexible packaging device; (d) Display of the negative electrode Zn foli.

[0038] Figure 16 Electrochemical performance of assembled flexible-pack wide voltage window devices: (a) CV curve; (b) CD curve; (c) specific capacitance at different current densities.

[0039] Figure 17 MnO electrodeposited directly using CFP x Composite materials: (a) CV curve; (b) CD curve; (c) Specific capacitance at different current densities. Detailed Implementation

[0040] The following examples illustrate specific implementation schemes related to the present invention. These are merely limited examples used to illustrate the implementation schemes of the present invention and do not limit the scope of the present invention.

[0041] Example 1:

[0042] 1. Electrodeposition of MnO on CFP x Electrode materials

[0043] First, CFP was hydrophilized. After weighing the hydrophilized CFP, it was added to a solution prepared with 0.4g KMnO4, 40mL deionized water, and 2mL 1M HCl for reaction. The mixture was stirred at 60℃ for two hours on a heating plate, and then reacted at room temperature for 12 hours. After that, it was washed with deionized water, dried, weighed, and tested to obtain CFP@MnO4. x -1; The above samples were electrochemically activated (CD cycles ≥ 5000 times, current density ≥ 5 A / g, window -0.1-1.1 V), then cleaned with 30% H2O2, followed by washing with deionized water, oven drying, weighing the CFP, and then testing and constant current electrodeposition (40 mA cm⁻¹). -2 Deposition was performed at a current density of 0.06 M Mn(CHCOO)2 and 0.06 M Na2SO4 in an electrolyte solution with a deposition area of ​​1 × 1 cm. 2 After deposition, the sample was washed with deionized water, dried, weighed, and then CFP@MnO was obtained. x .

[0044] This invention first uses MnO x MnO was grown on CFP, and then the grown MnO was... x After shearing and cleaning, and further electrodeposition, CFP@MnO was finally obtained. x Electrode material, namely CFP@MnO x Interface treatment is crucial for improving electrochemical performance.

[0045] 2. Preparation of Na₂SO₄ and NaOH electrolytes

[0046] To prepare 1M Na2SO4, 14.2 g of Na2SO4 was dissolved in 100 mL of deionized water with stirring. The solution was stirred at room temperature for 2 h and became clear.

[0047] To prepare 1M NaOH, dissolve 4g of NaOH in 100mL of deionized water with stirring. Stir at room temperature for 2 hours until the solution becomes clear.

[0048] 3. Construction of wide voltage window superelectric devices

[0049] (1) Assemble the three-electrode system and electrodeposit 1×1cm MnO on a CFP. x The active material was 0.06 M Mn(CH3COO)2 and Na2SO4 as the electrodeposition solution. The mass of the electrodeposition material before and after electrodeposition was weighed and the load was calculated. After washing with deionized water and drying, it was used as the working electrode. A 1 M Na2SO4 solution was used as the electrolyte, Ag / AgCl as the reference electrode, and a Pt sheet as the counter electrode (CFP@MnO). x The electrode material was used as the working electrode, and its electrochemical performance in a three-electrode system was tested.

[0050] (2) Assemble into a device, electrodeposit MnO on CFP. x Electrode materials: Zn foil was used as the negative electrode material, and the positive and negative electrodes were prepared according to the three-electrode system steps. Na2SO4 and NaOH electrolytes were placed in the positive and negative electrode electrolyte tanks, respectively, separated by a cation exchange membrane, to obtain a wide voltage window superelectric water system device.

[0051] The following conclusions can be drawn from the attached diagram:

[0052] Figure 1 The SEM images revealed the rod-like morphology of the CFP, and at high magnification, it can be seen that it has a relatively large specific surface area, which can provide corresponding attachment sites.

[0053] Figure 2 The SEM image shows the morphology of MnO2 grown on CFP due to the strong oxidizing properties of KMnO4 and the reducing properties of carbon. Under high magnification, it appears as round particles.

[0054] Figure 3 CFP@MnO after H2O2 treatment x SEM at -1 magnification showed no rounded particles in the attached material, but corresponding attachment points were visible under high magnification.

[0055] Figure 4 The SEM image in the image, and the final synthesized CFP@MnOx It presents an overall sheet-like morphological structure.

[0056] Figure 5 Mid-TEM images further validated CFP@MnO x In the scanned image, the active material is attached to the substrate.

[0057] Figure 6 For CFP@MnO x The energy spectrum of the electrode material clearly shows the uniform distribution of C, Mn, and O, proving the successful electrodeposition of MnO. x .

[0058] Figure 7 It is CFP@MnO x TEM and corresponding SAED images of the electrode material under a transmission electron microscope.

[0059] Figure 8 For CFP@MnO x The XRD patterns of the electrode materials demonstrate the successful synthesis of Mn3O4 and MnO2 (MnO4, MnO2, MnO2, MnO2) on carbon fiber paper. x These are two manganese-based oxides.

[0060] Figure 9 This is an electrochemical performance test of the electrode material directly grown by CFP using KMnO4 in a three-electrode system. Figure 9 (a) The CV curve shows that the current response to voltage exhibits approximately symmetry, indicating that the material has a reversible reaction; Figure 9 (b) The CD curve is approximately an isosceles triangle, indicating that the material has good electrical conductivity; Figure 9 (c) represents the specific capacitance at different current densities. At 1 A / g, the specific capacitance of the material is 134.2 F / g. At current densities of 1, 2, 5, 10 and 20 A / g, the specific capacitances of the electrode are 134.2, 120.4, 99, 80 and 64 F / g, respectively, which are relatively low.

[0061] Figure 10 CFP@MnO after cleaning with H2O2 x Electrochemical performance of -1 in a three-electrode system: Figure 10 (a) The CV curve does not show obvious polarization; Figure 10 (b) The CD curve is not like an isosceles triangle and has a relatively low Coulomb efficiency; Figure 10 (c) Specific capacitance at different current densities, where 1 mA / cm 2 At that time, the specific capacitance of the material was 46.4 F / cm. 2 At current densities of 1, 2, 5, and 10 mA / cm2 At these times, the specific capacities of the electrodes were 46.4, 32.2, 23, and 18 F / cm³, respectively. 2 This indicates that the capacity is very low.

[0062] Figure 11 For CFP@MnO x Testing of electrode materials in a three-electrode system Figure 11 (a) The CV curve shows that there is no obvious polarization phenomenon, indicating that the material has excellent supercapacitor characteristics and highly reversible reaction. Figure 11 (b) The CD curve of the sample is approximately an isosceles triangle and there is no obvious voltage drop, indicating that the electrode material has good conductivity and good capacitance behavior. Figure 11 (c) The specific capacitance of the electrode material calculated from the CD curve shows a high specific capacitance of 760.5 F / g at a current density of 1 A / g. The specific capacitances at current densities of 1, 2, 5, 10, and 20 A / g are 760.5, 680.4, 596.5, 539, and 442 F / g, respectively. At a current density of 5 A / g, the capacity retention is 100%, indicating relatively good rate performance. The CFP@MnO obtained through this example... x The electrode material showed almost no change in capacity after 3000 cycles of constant current charge-discharge at 5A / g, indicating that the electrode material has excellent cycle stability.

[0063] Figure 12 For CFP@MnO x The electrochemical performance of the electrode material in the three-electrode system at different windows is as follows: the specific capacity of the electrode is 760.5 C / g in the -0.1-0.9 V window at 1 A / g, 836.8 C / g in the -0.1-1.0 V window, and 896.6 C / g in the -0.1-1.1 V window.

[0064] Figure 13 For CFP@MnO x The electrochemical performance of the electrode material under high loading in a three-electrode system at different windows was studied. At a current density of 0.5 A / g and a window of -0.1 to 0.9 V, the specific capacity of the electrode was 407.8 F / g. At current densities of 1, 2, 5 and 10 A / g, the specific capacities of the electrode were 387, 349, 283.5 and 200 F / g, respectively.

[0065] Figure 14 Electrochemical performance of wide voltage window superelectric devices Figure 14As shown in CV and CD curves (a) and (b), no significant side reactions occur when the voltage window is 2.6V, indicating relative stability. Calculations from the CD curves show that at a current density of 0.5A / g, the device specific capacity reaches 568.99 F / g, which translates to an energy density of 400.67Wh / kg at a power density of 975 W / kg, significantly improving the MnO… x Energy density of superelectric devices. Figure 14 (e) Ragone plot, the device achieves a maximum specific energy of 400.67 Wh / kg at a power density of 975 W / kg, which shows superior performance compared to other superelectric devices. Therefore, our novel wide-voltage superelectric device has a greater advantage over other superelectric devices.

[0066] Figure 15 This is a diagram illustrating a novel wide-voltage window superelectric device in flexible packaging. The positive and negative electrodes are separately encapsulated and separated by a cation exchange membrane. Figure 15 (a) is a schematic diagram of the entire device; Figure 15 (b), (c), and (d) provide a comprehensive view from the positive, side, and negative electrodes.

[0067] Figure 16 Electrochemical performance of wide voltage window ultra-high voltage devices in flexible packaging. Figure 16 As can be seen from the CV and CD curves (a) and (b), no significant side reactions occur when the voltage window is 2.6V. The CD curves show that the device has a specific capacity of 188.45F / g at a current density of 1A / g, which translates to an energy density of 132.7Wh / kg at a power density of 1950W / kg. However, the graphs also show a significant voltage drop, which may be related to the relatively high resistance of the cation exchange membrane we used. We will improve the device by reducing this resistance in future work.

[0068] Figure 17 Direct electrodeposition of MnO by CFP x Electrochemical performance of electrode materials at different windows in a three-electrode system. Figure 17 (a) The CV curves show no obvious polarization, indicating that the material has a highly reversible reaction. Figure 17 (b) The CD curve of the sample is approximately an isosceles triangle and there is no obvious voltage drop, indicating that the electrode material has good conductivity and good capacitance behavior. Figure 17 (c) The specific capacitance of the electrode material calculated from the CD curve is 301 F / g at a current density of 1 A / g. The specific capacitance of the electrode is 301, 272, 239.5, 211 and 175.8 F / g at current densities of 1, 2, 5, 10 and 20 A / g, respectively.

[0069] Example 2:

[0070] 1. Electrodeposition of MnO on CFP x Electrode materials

[0071] CFP@MnO x For the preparation of the electrode material, please refer to Example 1.

[0072] 2. The preparation of Na2SO4 and NaOH electrolytes is the same as in Example 1.

[0073] 3. Construction of wide voltage window superelectric devices

[0074] The obtained CFP@MnO x Electrode materials were prepared according to the steps in Example 1, and their performance was tested in a three-electrode system. Figure 14 (a) The CV curve shows that its redox peaks are obvious and the polarization phenomenon is not obvious. Figure 14 (b) The CD curve of the sample shows a significant voltage drop, indicating that the resistance is relatively large, which is related to the ion transport capacity of the cation membrane. Figure 14 (c) The specific capacitance of this water-based superelectric device, calculated from the CD curve and based on the cathode material, shows a high specific capacitance of 568.9 F / g at a current density of 0.5 A / g, indicating a high capacity. At 1, 2, and 5 A / g, the specific capacitances are 448.84, 305.07, and 118.07 F / g, respectively. At a current density of 5 A / g, the capacity retention after 7000 cycles is 83.1%, indicating relatively good cycle stability. 1M Na₂SO₄ was used as the cathode material for CFP@MnO₂. x The electrolyte is 1M NaOH as the negative electrode electrolyte for the Zn foil. The cation exchange membrane only allows cations to pass through, so only Na+ ions can pass through. + Conduction occurs because the negatively charged groups in the cation exchange membrane used repel Zn(OH)4. 2- Transmembrane transport prevents Zn dendrite growth across the membrane, eliminating the performance and safety hazards posed by Zn dendrites to devices.

[0075] Example 3:

[0076] 1. CFP@MnO x Preparation of electrode materials

[0077] CFP@MnO x For the preparation of the electrode material, please refer to Example 1.

[0078] 2. Preparation of Na2SO4 and NaOH electrolyte

[0079] For the preparation of Na2SO4 and NaOH electrolytes, please refer to Example 1.

[0080] Figure 11 Electrodeposition of 1.3 mg-MnO2 on CFP for 100 s x In the test of the three-electrode system Figure 11 (a) The CV curve shows that there is no obvious polarization phenomenon, indicating that the material has excellent supercapacitor characteristics and highly reversible reaction. Figure 11 (b) The CD curve of the sample is approximately an isosceles triangle and there is no obvious voltage drop, indicating that the electrode material has good conductivity and good capacitance behavior. Figure 11 (c) The specific capacitance of the electrode material calculated from the CD curve is as high as 760.5 F / g at a current density of 1 A / g. At current densities of 1, 2, 5, 10 and 20 A / g, the specific capacitances of the electrode are 760.5, 680.4, 596.5, 539 and 442 F / g, respectively, which shows relatively high capacity.

[0081] Figure 13 Electrodeposition of 3.2 mg-MnO2 on CFP for 300 s x Testing of electrode materials in a three-electrode system Figure 13 (a) The CV curve shows no obvious polarization phenomenon, indicating that the material has excellent supercapacitor characteristics and highly reversible reaction. Figure 13 (b) The CD curve of the sample is approximately an isosceles triangle and does not show a significant voltage drop, indicating that the electrode material has good conductivity. Figure 13 (c) The specific capacitance of the electrode material calculated from the CD curve is as high as 407.8 F / g at a current density of 0.5 A / g. The specific capacitance of the electrode is 407.8, 387, 349, 283.5 and 200 F / g at current densities of 0.5, 1, 2, 5 and 10 A / g, respectively, indicating relatively good rate performance.

[0082] Example 4:

[0083] 1. CFP@MnO x Preparation of electrode materials

[0084] CFP@MnO x For the preparation of the electrode material, please refer to Example 1.

[0085] 2. Preparation of Na2SO4 and NaOH electrolyte

[0086] For the preparation of Na2SO4 and NaOH electrolytes, please refer to Example 1.

[0087] 3. Construction of assembled wide-voltage-window superelectric components

[0088] The positive electrode was prepared according to the three-electrode system preparation method. CFP@MnO was used. x Using the positive electrode material and Zn as the negative electrode, a flexible, encapsulated device is assembled. The positive electrode electrolyte is 1M Na₂SO₄, and the negative electrode electrolyte is 1M NaOH, separated by a cation exchange membrane. This allows for a voltage window of 1.3-2.6V, improving the energy density of the supercapacitor. Furthermore, these devices are easy to carry and assemble. At a current density of 1A / g, the device achieves a specific capacitance of 188.45F / g, which translates to an energy density of 132.7Wh / kg at a power density of 1950W / kg. Figure 15 (a) We can see the overall layout of the flexible packaging device, and the positive and negative terminals are connected for testing. Figure 16 (a) CV curve and (b) CD curve. The graphs show a voltage drop of approximately 0.4V at a current density of 1A / g, indicating a relatively high resistance. At this point, the device's specific capacitance reaches 188.45F / g, meaning an energy density of 132.7Wh / kg at a power density of 1950W / kg. At a current density of 2A / g, the specific capacitance reaches 132.99F / g, meaning an energy density of 93.64Wh / kg at a power density of 974.92W / kg. At a current density of 5A / g, the specific capacitance reaches 31.54F / g, meaning an energy density of 43.33Wh / kg at a power density of 389.97W / kg. Compared to the dual-slot wide-voltage water system device, the specific energy decreases significantly. We speculate that this decrease is related to the resistance.

[0089] Example 5:

[0090] 1. CFP@MnO x Preparation of electrode materials

[0091] CFP@MnO x For the preparation of the electrode material, please refer to Example 1.

[0092] 2. Preparation of Na2SO4 and NaOH electrolyte

[0093] For the preparation of Na2SO4 and NaOH electrolytes, please refer to Example 1.

[0094] 3. CFP and MnO prepared by different methods x Comparison of composite material properties.

[0095] Figure 9 This is an electrochemical performance test of the electrode material directly grown by CFP using KMnO4 in a three-electrode system. Figure 9 (a) The CV curve shows that the current response to voltage exhibits approximately symmetry, indicating that the material has a reversible reaction; Figure 9(b) The CD curve is approximately an isosceles triangle, indicating that the material has good electrical conductivity; Figure 9 (c) represents the specific capacitance at different current densities. At 1 A / g, the specific capacitance of the material is 134.2 F / g. At current densities of 1, 2, 5, 10 and 20 A / g, the specific capacitances of the electrode are 134.2, 120.4, 99, 80 and 64 F / g, respectively, which are relatively low.

[0096] Figure 17 Direct electrodeposition of MnO by CFP x Electrochemical performance of electrode materials at different windows in a three-electrode system. Figure 17 (a) The obvious polarization phenomenon in the CV curve indicates that the material has a highly reversible reaction. Figure 17 (b) The CD curve of the sample is approximately an isosceles triangle and there is no obvious voltage drop, indicating that the electrode material has good conductivity and good capacitance behavior. Figure 17 (c) The specific capacitance of the electrode material calculated from the CD curve is as high as 301 F / g at a current density of 1 A / g. At current densities of 1, 2, 5, 10 and 20 A / g, the specific capacitances of the electrode are 301, 272, 239.5, 211 and 175.8 F / g, respectively, and the material has good rate performance.

[0097] Figure 11 For CFP@MnO x In the test of the three-electrode system Figure 11 (a) The CV curve shows that there is no obvious polarization phenomenon, indicating that the material has excellent supercapacitor characteristics and highly reversible reaction. Figure 11 (b) The CD curve of the sample is approximately an isosceles triangle and there is no obvious voltage drop, indicating that the electrode material has good conductivity and good capacitance behavior. Figure 11 (c) The specific capacitance of the electrode material calculated from the CD curve is as high as 760.5 F / g at a current density of 1 A / g. At current densities of 1, 2, 5, 10 and 20 A / g, the specific capacitances of the electrode are 760.5, 680.4, 596.5, 539 and 442 F / g, respectively, which shows relatively high capacity.

Claims

1. A method for electrodepositing MnO on carbon fiber paper x The method for preparing the material is characterized by Includes the following steps: Step 1: Add carbon fiber paper (CFP) to a mixed solution of concentrated nitric acid and concentrated sulfuric acid in a volume ratio of 3:1, stir at 60-80℃ for 3-8 hours, rinse repeatedly with deionized water until neutral and dry. Step 2: Add 0.1-20g KMnO4 to 10-100mL of deionized water, stir to disperse evenly, and then add 2-10mL of 1M HCl solution. Add the hydrophilicated CFP from Step 1 to the above solution and react fully for 12h. Then wash with deionized water and dry to obtain CFP@MnO4. x -1; Step 3: Take the CFP@MnO obtained in Step 2 x -1 is subjected to electrochemical activation cycle treatment, then washed with 30% H2O2 solution, followed by washing with deionized water and drying; Step 4: Place the material obtained in Step 3 into the electrodeposition solution for constant current electrodeposition. After deposition, wash with deionized water and dry to obtain CFP@MnO. x Material; In step 3, the electrolyte used in the electrochemical activation cycle treatment is a 0.1M-3M Na2SO4 solution; In step 3, during the electrochemical activation cycle treatment, the number of cycles is ≥5000, the current density is ≥5A / g, and the window is -0.1-1.1V; In step 4, the electrodeposition solution is a mixture of 0.01M-1M Mn(CH3COO)2 and 0.01M-1M Na2SO4.

2. The preparation method according to claim 1, characterized in that: In step 4, the electrodeposition solution is a mixture of 0.06M Mn(CH3COO)2 and 0.06M Na2SO4.

3. The preparation method according to claim 1, characterized in that: In step 4, the constant current electrodeposition time is 50-600 s, and the current is 10-400 mA / cm². 2 Deposition is performed using a current density.

4. The preparation method according to claim 3, characterized in that: In step 4, the constant current electrodeposition time is 300 s, using 40 mA / cm². 2 Deposition is performed using a current density.

5. CFP@MnO prepared by any one of the preparation methods according to claims 1-4 x Application of materials in the construction of high-energy-density supercapacitors.

6. The application according to claim 5, characterized in that: With the CFP@MnO x Using Zn foil as the negative electrode material and Na2SO4 and NaOH as the positive and negative electrolytes respectively, and adding a cation separator, a supercapacitor with a wide voltage window is assembled.

Images