Polypyrrole / titanium oxycarbide electrode based on stainless steel current collector

Abstract

The invention discloses a polypyrrole / hydroxy titanium carbide electrode based on a stainless steel current collector, and belongs to the technical field of supercapacitors. An electrolyte containing 0.1 mol / L of pyrrole monomer, 0.025-0.050 mol / L of lauryl sodium sulfate and 1-2 g / L of titanium oxycarbide is prepared, a 600-mesh 316 L stainless steel wire mesh serves as a working electrode, electrochemical deposition is conducted in a three-electrode system under the conditions that T is larger than or equal to 0 DEG C and smaller than or equal to 50 DEG C, and t is larger than or equal to 1600 s, and the electrode with the active substance deposition density being 1-15 mg / cm < 2 > is prepared. The active substance composite structure enables the polypyrrole and the titanium oxycarbide to store energy synergistically, the electrode avoids a binder, and is high in binding force, large in specific surface area, stable in structure, suitable for multiple types of electrolytes, flexible, simple and convenient to prepare and easy to industrialize.

Description

Technical Field

[0001] The invention relates to an electrode for directly growing a polypyrrole / hydroxytitanium carbide active material on a stainless steel current collector and a preparation method thereof, belonging to the technical field of supercapacitors. Background Art

[0002] Supercapacitors are green energy storage devices with advantages such as fast charging and discharging, high power density, and long cycle life. They have great development potential in energy storage. Supercapacitors are mainly composed of components such as electrodes, diaphragms, electrolytes, and packaging materials. The electrodes are the key part, consisting of active materials and current collectors. The traditional electrode preparation method is to mix the active material with a conductive agent and a binder by mixing and slurrying, and then coating or rolling it on the current collector. On the one hand, this method inevitably introduces a binder, thereby increasing the ineffective mass and reducing the specific capacitance of the electrode. On the other hand, the bonding strength between the active material and the current collector is limited, which not only increases the contact resistance, but also causes the material to fall off during the charging and discharging process, affecting the life of the device. Compared with the traditional preparation method, growing the active material directly on the current collector can not only improve the utilization rate of the electrode material, but also effectively reduce the contact resistance between the active material and the current collector, and enhance the stability of the electrode structure.

[0003] Regarding active materials, polypyrrole (PPy) is a conjugated conductive polymer derived from carbon and nitrogen five-membered heterocyclic pyrrole monomers through oxidative polymerization. It relies on Faradaic reactions for energy storage and is considered to possess pseudocapacitive energy storage properties. In supercapacitor applications, PPy offers advantages such as good conductivity, high redox activity, and environmental safety. However, it is prone to irreversible volume changes during rapid charge and discharge, resulting in poor structural stability and thus affecting its cycling performance. Composites with other functional materials are an effective approach to modifying PPy. Titanium hydroxycarbide (HTC), a two-dimensional layered material with tunable interlayer spacing and abundant surface functional groups, serves as an ideal matrix for constructing composite materials. It exhibits excellent electrochemical reactivity in energy storage applications and is adaptable to intercalation of different electrolyte ions. Composites of PPy nanoparticle aggregates with HTC nanofibers exploit the coordination mechanism between the two materials to enhance electrochemical energy storage properties and microstructural stability. Currently, few reports exist on PPy / HTC composite electrodes based on stainless steel current collectors and their electrochemical deposition preparation methods. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention proposes a polypyrrole / titanium hydroxycarbide electrode directly grown on a stainless steel current collector. This electrode, suitable for supercapacitors, features an active material composed of a composite of polypyrrole nanoparticle aggregates and titanium hydroxycarbide nanofibers. The polypyrrole is grown in situ on the current collector, and the titanium hydroxycarbide's rich surface functional groups provide active sites for polypyrrole binding.

[0005] The present invention adopts the following technical solutions:

[0006] A polypyrrole / hydroxytitanium carbide electrode based on a stainless steel current collector, characterized in that the polypyrrole / hydroxytitanium carbide electrode is prepared by the following method:

[0007] 1) Preparation of electrolyte: Prepare an aqueous solution of pyrrole monomer and sodium dodecyl sulfate, and slowly add the hydroxyl titanium carbide nanofiber dispersion under magnetic stirring to obtain a uniform electrolyte; the concentrations of pyrrole monomer, sodium dodecyl sulfate and hydroxyl titanium carbide in the electrolyte are 0.1 mol L -1 , 0.025-0.050 mol L -1 and 1-2g L -1 ;

[0008] 2. Preparation of electrodes: In a three-electrode system, a 600-mesh stainless steel wire mesh is used as the working electrode, a metal platinum sheet is used as the counter electrode, and Ag / AgCl is used as the reference electrode. The three electrodes are immersed in the electrolyte prepared in step 1, and a polypyrrole / hydroxytitanium carbide composite material is in situ grown on the stainless steel wire mesh by electrochemical deposition. The reaction temperature is in the range of 0°C ≤ T ≤ 50°C, and the reaction time t ≥ 1600s. The working electrode after the electrochemical deposition is soaked and rinsed in deionized water and then dried in a vacuum environment at 50°C to obtain an electrode with a stainless steel wire mesh as a current collector and a polypyrrole / hydroxytitanium carbide composite material as an active material.

[0009] The deposition density of the active material in the electrode on the stainless steel current collector is 1-15 mg cm -2 .

[0010] The length of the titanium hydroxycarbide nanofiber is between 100 and 1000 nanometers, and the diameter is between 5 and 20 nanometers.

[0011] The stainless steel model is 316L.

[0012] The present invention has the following advantages:

[0013] 1. The effective combination of polypyrrole and hydroxytitanium carbide can stimulate the coordination mechanism between them and optimize the energy storage properties of the electrode.

[0014] 2. The one-dimensional structure formed by the self-growth of polypyrrole nanoparticles and the nanofiber structure of titanium hydroxycarbide both have large specific surface areas, which can increase the active sites of electrochemical reactions.

[0015] 3. Directly growing polypyrrole / hydroxytitanium carbide composite materials on stainless steel wire mesh is beneficial to enhancing the binding force between the current collector and the active material on the one hand, and on the other hand, it helps to enhance the stability of the active material's own microstructure and improve the cycle performance of the electrode.

[0016] 4. Stainless steel mesh, polypyrrole, and hydroxy titanium carbide all have high chemical stability, and polypyrrole / hydroxy titanium carbide is suitable for the insertion and removal of different ions. Therefore, the electrode can work in different types of electrolytes, such as acidic, neutral, and alkaline. Stainless steel mesh is flexible, so the electrode can be used as a flexible electrode.

[0017] 5. The preparation method of the present invention avoids the tedious preparation process, simplifies the process, is easy to implement, and is suitable for industrial production.

[0018] The polypyrrole / hydroxytitanium carbide active material uses a stainless steel mesh as a growth site, where pyrrole monomers are electropolymerized to form polypyrrole nanoparticles. The nanoparticles gradually deposit and grow along a specific direction, forming a one-dimensional structure. The one-dimensional polypyrrole structure and the titanium carbide nanofibers are intertwined through the active sites to form a three-dimensional network, providing numerous channels for electrolyte ion transport. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a scanning electron microscope image of the polypyrrole / hydroxytitanium carbide electrode based on the stainless steel current collector prepared in Example (1).

[0020] Figure 2 The electrode prepared in Example (1) was heated to 0.5 mol L -1 Cyclic voltammetry curves in H2SO4 electrolyte.

[0021] Figure 3 This is a scanning electron microscope image of the polypyrrole / hydroxytitanium carbide electrode based on the stainless steel current collector prepared in Example (2).

[0022] Figure 4 The electrode prepared in Example 2 was 0.5 mol L -1 Cyclic voltammetry curves in H2SO4 electrolyte. DETAILED DESCRIPTION

[0023] The present invention will be further described in detail below with reference to specific examples, but the present invention is not limited to these embodiments.

[0024] Example 1: Preparation of polypyrrole / titanium hydroxycarbide electrode based on stainless steel current collector by constant potential deposition

[0025] Step 1: Prepare 50 mL of electrolyte, in which the concentrations of pyrrole monomer, sodium dodecyl sulfate and titanium hydroxycarbide are 0.1 mol L -1 , 0.025 mol L -1 and 1g L -1 In the H-type electrolytic cell, the stainless steel mesh is the working electrode, the platinum sheet is the counter electrode, and the Ag / AgCl is the reference electrode. The three electrodes are immersed in the electrolyte, and the electrolyte temperature is maintained at 50°C using a constant temperature control system.

[0026] Step 2: Using an electrochemical workstation, select the current-time mode, set the constant voltage to 0.9 V, and the electrodeposition time to 1600 s.

[0027] Step 3: The working electrode with the black active material deposited was soaked and rinsed in deionized water, and then dried in a vacuum oven at 50 °C to obtain a polypyrrole / titanium hydroxycarbide electrode based on a stainless steel current collector. The deposition density of the active material on the current collector was 3.7 mg cm -2 .

[0028] Step 4: Select two electrodes prepared in step 3 as the positive and negative electrodes respectively, and use 0.5 mol L -1 The symmetrical supercapacitor is assembled using H2SO4 as the electrolyte, aqueous separator paper as the separator between the two electrodes, and a 2016-type battery case as the packaging material. The device operates within a voltage window of 0–1.0V.

[0029] Figure 1 This is a scanning electron microscope image of the electrode prepared in Example (1) of the present invention. The one-dimensional structure formed by the aggregation and growth of polypyrrole nanoparticles on the stainless steel current collector is entangled with the hydroxyl titanium carbide nanofibers to form a three-dimensional network structure. Figure 2 The electrode prepared in Example 1 is 0.5 mol L -1 In H2SO4 electrolyte, 2mV s -1 The cyclic voltammetry curve at the scan rate was calculated to have a mass specific capacitance of 99 F g -1 .

[0030] Example 2: Preparation of polypyrrole / titanium hydroxycarbide electrodes based on stainless steel current collectors by cyclic voltammetric deposition

[0031] Step 1, step 3 and step 4 are consistent with the corresponding steps in Example 1. The deposition density of the active material on the working electrode is 3.3 mg cm -2 The difference between step 2 and embodiment (1) is that: using an electrochemical workstation, select the cyclic voltammetry scanning mode, the scanning potential is 0-0.9V, and the scanning rate is 20mV s-1 , the number of scanning cycles is 60.

[0032] Figure 3 This is a scanning electron microscope image of the electrode prepared in Example (II) of the present invention. Dense polypyrrole nanoparticles are coated on the stainless steel current collector, and hydroxyl titanium carbide nanofibers are clearly visible, with polypyrrole nanoparticles grown on their surface. Figure 4 The electrode prepared in Example 2 was heated to 0.5 mol L -1 In H2SO4 electrolyte, 2mV s -1 The cyclic voltammetry curve at the scan rate was calculated to have a mass specific capacitance of 122 F g -1 .

[0033] Using electrochemical deposition technology to grow the active material in situ on the current collector, polypyrrole nanoparticle aggregates are combined with hydroxy titanium carbide nanofibers to produce a highly chemically stable and flexible electrode in a single step, reducing the number of electrode preparation steps and optimizing the process flow. The direct bonding of the active material to the current collector reduces contact resistance and improves the structural stability of the electrode. The inherent adhesive properties of hydroxy titanium carbide enhance the binding force between the active materials, eliminating the need for a binder and increasing the utilization rate of the active materials. The entire electrode preparation process is simple to operate, easy to control, and low-cost.

Claims

1. A polypyrrole / titanium hydroxycarbide electrode based on a stainless steel current collector, characterized in that: The polypyrrole / hydroxytitanium carbide electrode is prepared by the following method: 1) Preparation of electrolyte: An aqueous solution of pyrrole monomer and sodium dodecyl sulfate was prepared, and a dispersion of hydroxyl titanium carbide nanofibers was slowly added under magnetic stirring to obtain a uniform electrolyte; the concentrations of pyrrole monomer, sodium dodecyl sulfate, and hydroxyl titanium carbide in the electrolyte were 0.1 mol L -1 , 0.025 − 0.050 mol L -1 and 1 − 2 g L -1 ; 2) Electrode Preparation: In a three-electrode system, a 600-mesh stainless steel wire mesh is used as the working electrode, a platinum sheet is used as the counter electrode, and Ag / AgCl is used as the reference electrode. The three electrodes are immersed in the electrolyte prepared in step 1. A polypyrrole / hydroxytitanium carbide composite material is in situ grown on the stainless steel wire mesh by electrochemical deposition. The reaction temperature is in the range of 0°C ≤ T ≤ 50°C, and the reaction time t ≥ 1600 s. The electrochemically deposited working electrode is soaked and rinsed in deionized water and then dried in a vacuum environment at 50°C to obtain an electrode with a stainless steel wire mesh as the current collector and a polypyrrole / hydroxytitanium carbide composite material as the active material.

2. The polypyrrole / hydroxytitanium carbide electrode according to claim 1, characterized in that The deposition density of the active material polypyrrole / hydroxytitanium carbide composite material in the electrode on the stainless steel current collector is 1-15 mg cm -2 .

3. The polypyrrole / hydroxytitanium carbide electrode according to claim 1, characterized in that The length of the titanium hydroxycarbide nanofibers is between 100 and 1000 nanometers, and the diameter is between 5 and 20 nanometers.

4. The polypyrrole / hydroxytitanium carbide electrode according to claim 1, characterized in that The stainless steel model is 316L.

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