A method for activating a high-loading manganese dioxide electrode material

Abstract

The application relates to an activation method of a high-loading manganese dioxide electrode material, in particular to in-situ growth of a high-loading manganese dioxide electrode material with a loading of greater than or equal to 15 mg cm ‑2 on a flexible carbon cloth surface, taking the high-loading manganese dioxide electrode material as a working electrode, taking a metal Pt sheet as a counter electrode, adopting a two-electrode system, activating the high-loading manganese dioxide in a zinc nitrate solution through cyclic voltammetry scanning, and the activated high-loading manganese dioxide exhibits excellent electrochemical properties. The application adopts an electric activation method to improve the electrochemical activity of the high-loading manganese dioxide, has the advantages of simple process, convenient operation and the like, and the activated high-loading manganese dioxide electrode material can be used for electrochemical energy storage.

Description

Technical Field

[0001] This invention relates to an activation method for a high-load manganese dioxide electrode material, specifically belonging to the field of electrochemical technology. Background Technology

[0002] Supercapacitors have attracted widespread attention in the energy storage field due to their fast charging and discharging speeds, high power density, and long cycle life. However, improving the energy density of supercapacitors remains a challenging task in practical applications. According to the supercapacitor energy density formula E=1 / 2 CV... 2 The energy density of supercapacitors can be increased by improving the specific capacitance of the active material and broadening the potential range. Manganese dioxide, as a typical pseudocapacitive material, has been widely studied as an electrode material for supercapacitors due to its low cost, high natural abundance, high theoretical capacitance (≈1370 F / g), and wide operating potential window (≈1V in aqueous electrolytes). The pseudocapacitance of manganese dioxide electrode materials mainly originates from Mn. 3+ / Mn 4+ The redox reaction occurs on or near the surface of manganese dioxide, and the internal volume of manganese dioxide, which is a dead active site, contributes almost nothing to the capacitance, resulting in low utilization efficiency of manganese dioxide. This limits the practical application of manganese dioxide as a high-performance electrode material for supercapacitors.

[0003] To date, various strategies have been developed to modify manganese dioxide electrodes to improve manganese dioxide utilization efficiency. These include constructing nano-level structures to increase surface area (Electrochimica Acta, 2013, 89, 523-529), inserting cations to expand interlayer spacing (Nanomaterials, 2022, 12(16), 2856), and constructing composite materials with conductive components (ACS Applied Materials & Interfaces, 2016, 8(36), 23721-23728). The resulting manganese dioxide electrode materials exhibit significantly improved capacitance performance. However, the superior performance of most manganese dioxide electrodes is only achieved at very low loadings (approximately 2 mg / cm³). 2 This is achieved at a load far lower than that used in commercial energy storage devices (≈10 mg / cm³). 2 Typically, manganese dioxide has a low inherent mass migration rate. As the electrode material thickness increases, its internal mass migration is significantly inhibited, leading to a substantial decrease in its electrochemical performance with increasing electrode loading and thickness. Therefore, a simple and efficient method is sought to improve the performance of manganese dioxide at loadings higher than those in commercial energy storage devices (≥10 mg / cm³). 2 The electrochemical activity of ) still faces enormous challenges. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide an activation method for a high-loading manganese dioxide electrode material. After activation, the high-loading manganese dioxide exhibits significantly enhanced electrochemical activity and can be used for electrochemical energy storage.

[0005] The present invention discloses an activation method for a high-load manganese dioxide electrode material. The method involves using flexible carbon cloth as a substrate and growing manganese dioxide in situ on the surface of the flexible carbon cloth through a redox reaction between potassium permanganate and the carbon cloth. The high-load manganese dioxide is activated by using the flexible carbon cloth with high-load manganese dioxide deposition as the working electrode and a metal Pt sheet as the counter electrode in a zinc nitrate solution.

[0006] The specific process is as follows:

[0007] Step 1: Deposition of high-load manganese dioxide on flexible carbon cloth

[0008] Flexible commercial carbon cloth treated with N2 plasma was placed in potassium permanganate solution and reacted at 160°C under closed conditions for 3 hours. After the reaction, a high loading of manganese dioxide was deposited in situ on the surface of the flexible carbon cloth. After washing with deionized water, it was dried at 60°C for 12 hours.

[0009] Step 2: Activation with high loading of manganese dioxide

[0010] A two-electrode system was used, with flexible carbon cloth deposited with a high manganese dioxide loading as the working electrode and a metal Pt sheet as the counter electrode. The high manganese dioxide loading was activated in zinc nitrate solution using a cyclic voltammetric scanning method.

[0011] The nitrogen plasma treatment has a power of 100 W, a time of 250 s, and a nitrogen pressure of 35 Pa.

[0012] The model number of the flexible commercial carbon cloth is W0S1011-21020501.

[0013] The manganese dioxide is δ-MnO2 nanosheets with a thickness of 10~20 nm.

[0014] The concentration of the zinc nitrate solution is 0.5~2 mol / L.

[0015] The concentration of the potassium permanganate solution is 65.8 mmol / L.

[0016] The test parameters for the cyclic voltammetric scan are: scan voltage of -2 to 2 V, and scan rate of 5 to 50 mV / s. -1 The number of scan cycles is 1 to 20.

[0017] The high-loading manganese dioxide has a loading of ≥15 mg / cm³. -2 .

[0018] Beneficial effects of this invention: The activation method described in this invention has the advantages of simple process and convenient operation, and the loading of manganese dioxide on the surface of flexible carbon cloth is ≥15 mg cm⁻¹. -2 The specific capacitance is significantly improved after activation, making it well applicable to the field of electrochemical energy storage. Attached Figure Description

[0019] Figure 1 This is a cyclic voltammetric curve of the high-load manganese dioxide prepared in Example 1 of the present invention before and after activation;

[0020] Figure 2 The constant current charge-discharge curves of the high-load manganese dioxide prepared in Example 1 of this invention before and after activation are shown. Detailed Implementation

[0021] Example 1

[0022] Step 1: Deposition of high-load manganese dioxide on flexible carbon cloth

[0023] A 2×3cm flexible commercial carbon cloth (model: W0S1011-21020501) treated with N2 plasma (power: 100 W; time: 250 s; N2 pressure: 35 Pa) was placed in 40 mL of potassium permanganate solution (65.8 mmol / L) and reacted at 160℃ under sealed conditions for 3 h. Through the redox reaction between potassium permanganate and carbon cloth, a dense layer of δ-MnO2 was uniformly deposited on the surface of the carbon cloth, with a loading of 18 mg / cm³. -2 After being washed with deionized water, it was dried in an oven at 60°C for 12 hours.

[0024] Step 2: Activation with high loading of manganese dioxide

[0025] A two-electrode system was used, with flexible carbon cloth deposited with high manganese dioxide as the working electrode and a metal Pt sheet as the counter electrode. The high manganese dioxide was activated in a 1 mol / L zinc nitrate solution using cyclic voltammetry (scanning voltage: -1~1 V; scan rate: 50 mV / s; number of scan cycles: 1).

[0026] Step 3: Evaluation of capacitive properties before and after activation with high-load manganese dioxide

[0027] At 25℃, a three-electrode system was used to evaluate the capacitive properties of high-load manganese dioxide before and after activation using cyclic voltammetry and constant current charge-discharge modes. High-load manganese dioxide was used as the working electrode, a Pt metal sheet as the counter electrode, and Ag / AgCl as the reference electrode. The electrolyte was a 1 mol / L sodium sulfate aqueous solution. Cyclic voltammetry curves (…) Figure 1 It can be clearly seen that the cyclic voltammetric area of ​​high-load manganese dioxide after activation is significantly larger than that before activation; at the same time, based on the constant current charge-discharge curve ( Figure 2 ) Calculation, at 5 mA / cm 2 At that time, the areal specific capacitance and gravimetric specific capacitance of the activated high-load manganese dioxide electrode material were 3240 mF / cm², respectively. -2 and 203 F g -1 It is 2.4 times that before activation.

[0028] Example 2

[0029] Step 1: Deposition of high-load manganese dioxide on flexible carbon cloth

[0030] A 3×3cm flexible commercial carbon cloth (model: W0S1011-21020501) treated with N2 plasma (power: 100 W; time: 250 s; N2 pressure: 35 Pa) was placed in 50 mL of potassium permanganate solution (65.8 mmol / L) and reacted at 160℃ under sealed conditions for 3 h. Through the redox reaction between potassium permanganate and the carbon cloth, a dense layer of δ-MnO2 was uniformly deposited on the surface of the carbon cloth, with a loading of 15 mg / cm³. -2 After being washed with deionized water, it was dried in an oven at 60°C for 12 hours.

[0031] Step 2: Activation with high loading of manganese dioxide

[0032] A two-electrode system was used, with flexible carbon cloth deposited with high manganese dioxide as the working electrode and a metal Pt sheet as the counter electrode. The high manganese dioxide was activated in a 0.5 mol / L zinc nitrate solution using cyclic voltammetry (scanning voltage: -0.5~0.5 V; scan rate: 20 mV / s; number of scan cycles: 20).

[0033] Step 3: Evaluation of capacitive properties before and after activation with high-load manganese dioxide

[0034] At 25℃, a three-electrode system was used to evaluate the capacitive properties of high-load manganese dioxide before and after activation via cyclic voltammetry and galvanostatic charge-discharge modes. High-load manganese dioxide was used as the working electrode, a Pt metal sheet as the counter electrode, and Ag / AgCl as the reference electrode. The electrolyte was a 1 mol / L sodium sulfate aqueous solution. Cyclic voltammetry curves clearly showed that the cyclic voltammetric area of ​​the high-load manganese dioxide was significantly larger after activation than before. Simultaneously, based on the galvanostatic charge-discharge curves, the capacitance at 5 mA / cm² was calculated. 2 At that time, the areal specific capacitance and gravimetric specific capacitance of the activated high-load manganese dioxide electrode material were 2970 mF / cm², respectively. -2 and 186 F g -1 It is 1.8 times that of the unactivated one.

[0035] Example 3

[0036] Step 1: Deposition of high-load manganese dioxide on flexible carbon cloth

[0037] A 4×4 cm flexible commercial carbon cloth (model: W0S1011-21020501) treated with N2 plasma (power: 100 W; time: 250 s; N2 pressure: 35 Pa) was placed in 100 mL of potassium permanganate solution (65.8 mmol / L) and reacted at 160 °C under sealed conditions for 3 h. Through the redox reaction between potassium permanganate and the carbon cloth, a dense layer of δ-MnO2 was uniformly deposited on the surface of the carbon cloth, with a loading of 17 mg / cm³. -2 After being washed with deionized water, it was dried in an oven at 60°C for 12 hours.

[0038] Step 2: Activation with high loading of manganese dioxide

[0039] A two-electrode system was used, with flexible carbon cloth deposited with high manganese dioxide as the working electrode and a metal Pt sheet as the counter electrode. The high manganese dioxide was activated in a 1 mol / L zinc nitrate solution using cyclic voltammetry (scanning voltage: -2~2 V; scan rate: 50 mV / s; number of scan cycles: 5).

[0040] Step 3: Evaluation of capacitive properties before and after activation with high-load manganese dioxide

[0041] At 25℃, a three-electrode system was used to evaluate the capacitive properties of high-load manganese dioxide before and after activation via cyclic voltammetry and galvanostatic charge-discharge modes. High-load manganese dioxide was used as the working electrode, a Pt metal sheet as the counter electrode, and Ag / AgCl as the reference electrode. The electrolyte was a 1 mol / L sodium sulfate aqueous solution. Cyclic voltammetry curves clearly showed that the cyclic voltammetric area of ​​the high-load manganese dioxide was significantly larger after activation than before. Simultaneously, based on the galvanostatic charge-discharge curves, the capacitance at 5 mA / cm² was calculated. 2 At that time, the areal specific capacitance and gravimetric specific capacitance of the activated high-load manganese dioxide electrode material were 3120 mF / cm², respectively. -2 and 195 F g -1 It is 2.1 times that of the unactivated one.

Claims

1. A method for activating a high-loading manganese dioxide electrode material, characterized in that, The method described above uses flexible carbon cloth as a substrate and grows manganese dioxide in situ on the surface of the flexible carbon cloth through the redox reaction of potassium permanganate and carbon cloth. The flexible carbon cloth with high manganese dioxide deposition is used as the working electrode and a metal Pt sheet is used as the counter electrode. The high manganese dioxide is activated in zinc nitrate solution using a cyclic voltammetric scanning method through the two electrode system. The specific process is as follows: Step 1: Deposition of high-load manganese dioxide on flexible carbon cloth Flexible commercial carbon cloth treated with N2 plasma was placed in potassium permanganate solution and reacted at 160°C under closed conditions for 3 hours. After the reaction, a high loading of manganese dioxide was deposited in situ on the surface of the flexible carbon cloth. After washing with deionized water, it was dried at 60°C for 12 hours. Step 2: Activation with high loading of manganese dioxide A two-electrode system was used, with flexible carbon cloth deposited with high manganese dioxide as the working electrode and a metal Pt sheet as the counter electrode. The high manganese dioxide was activated in zinc nitrate solution using cyclic voltammetry. The nitrogen plasma treatment has a power of 100 W, a time of 250 s, and a nitrogen pressure of 35 Pa. The concentration of the zinc nitrate solution is 0.5~2 mol / L; The test parameters for the cyclic voltammetric scan are: scan voltage of -2 to 2 V, and scan rate of 5 to 50 mV / s. -1 The number of scan cycles is 1 to 20.

2. The activation method for a high-loading manganese dioxide electrode material according to claim 1, characterized in that, The model number of the flexible commercial carbon cloth is W0S1011-21020501.

3. The activation method for a high-loading manganese dioxide electrode material according to claim 1, characterized in that, The manganese dioxide is δ-MnO2 nanosheets with a thickness of 10~20 nm.

4. The activation method for a high-loading manganese dioxide electrode material according to claim 1, characterized in that, The concentration of the potassium permanganate solution is 65.8 mmol / L.

5. The activation method for a high-loading manganese dioxide electrode material according to claim 1, characterized in that, The high-loading manganese dioxide has a loading of ≥15 mg / cm³. -2 .

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