CN113957566B - A kind of solid oxide battery composite nanofiber and preparation method thereof - Google Patents

Abstract

The invention discloses a solid oxide battery composite nanofiber and a preparation method thereof. According to the element ratio of BaGd _0.8 La _0.2 Co ₂ O ₅ (BGLC) and Gd _0.1 Ce _0.9 O _1.95 (GDC), barium nitrate, gadolinium nitrate, Lanthanum nitrate, cobalt nitrate and cerium nitrate were dissolved in DMF solvent, PVP was added as an organic binder, and after stirring evenly, a precursor solution was prepared for electrospinning to obtain a BGLC/GDC composite nanofiber precursor; the precursor fiber was calcined to obtain BGLC/GDC composite nanofibers. The preparation method has the characteristics of low cost, short process, simple process, safety and controllability, and the like. The diameter of the prepared composite nanofiber is only about 100-200nm, and the fiber length reaches tens of microns. Composite nanofibers with different morphologies can be obtained according to the different ratios of BGLC and GDC. It is of great significance to realize the development and application of solid oxide battery cathode nanofiber materials, and has broad application prospects in the field of fuel cell electrode preparation.

Description

A kind of solid oxide battery composite nanofiber and preparation method thereof

technical field

The invention belongs to the technical field of preparation of solid oxide battery electrode materials, and in particular relates to a solid oxide battery composite nanofiber and a preparation method thereof.

Background technique

Solid oxide fuel cell (SOFC) is an all-solid-state chemical power generation device that directly converts chemical energy stored in fuel and oxidant into electrical energy in an efficient and environmentally friendly manner. SOFC has higher energy conversion efficiency and wider fuel adaptability. It can directly use hydrogen, methane, etc. as fuel. The all-solid structure is safer and more environmentally friendly. The reaction kinetics of SOFC requires high temperature to proceed well, and obtain a sufficiently high electrical conductivity at high temperature. But high temperatures can cause thermal cycling instability, leading to agglomeration of cathode materials and reducing battery life. In order to improve battery performance at medium and low temperatures, materials with greater mixed ion-electronic conductivity and catalytic properties (MIEC) at medium and low temperatures are used to reduce the activation barrier, such as BaGd _0.8 La _0.2 Co ₂ O ₅ (BGLC), while The electrolyte material Gd _0.1 Ce _0.9 O _1.95 (GDC) was introduced into the cathode to increase the three-phase reaction interface and thus have better electrochemical performance. At the same time, the microstructure of the battery cathode can also be modified, and a one-dimensional nanofiber structure can be introduced into the cathode. The one-dimensional nanofiber can form a continuous transmission path, and the nanofiber has a small fiber diameter, a large specific surface area and a relatively small diameter. The large porosity makes the fiber material have more reaction sites, thereby improving the reactivity of the cathode.

However, for the preparation of composite cathode materials, many experiments require separate preparation of powder and mechanical mixing, or the introduction of the second phase by impregnation. These methods will lead to a more complicated preparation process and a longer time-consuming.

Contents of the invention

The purpose of the present invention is to provide a solid oxide battery composite nanofiber and a preparation method thereof, which uses an electrospinning method to prepare a SOFC cathode composite material in one step to obtain a BGLC/GDC composite nanofiber. The preparation process of the method is short, the process is simple, safe and controllable, and at the same time, the prepared fiber material has a large specific surface area and high catalytic activity.

To achieve the above object, the present invention adopts the following technical solutions:

The chemical composition of a solid oxide battery composite nanofiber is BaGd _0.8 La _0.2 Co ₂ O ₅ /Gd _0.1 Ce _0.9 O _1.95 .

The preparation method comprises the following steps:

(1) Dissolve barium nitrate, gadolinium nitrate, lanthanum nitrate, cobalt nitrate and cerium nitrate in N,N-dimethylformamide (DMF), stir to completely dissolve the nitrate, and obtain a nitrate-DMF solution;

(2) Add polyvinylpyrrolidone (PVP) into the nitrate-DMF solution, stir until completely dissolved, and obtain the spinning precursor solution;

(3) After the spinning precursor solution is ultrasonically oscillated, it is left to stand until the air bubbles are completely eliminated, and then electrospinning is performed to obtain a composite nanofiber precursor;

(4) Calcining the composite nanofiber precursor with heat preservation to obtain the composite nanofiber BaGd _0.8 La _0.2 Co ₂ O ₅ /Gd _0.1 Ce _0.9 O _1.95 .

In the step (1), the total mass of barium nitrate, gadolinium nitrate, lanthanum nitrate, cobalt nitrate and cerium nitrate in the mixed solution is 10%-15% of the mass of the DMF solvent.

In the step (1), the ratio of barium nitrate, gadolinium nitrate, lanthanum nitrate, cobalt nitrate and cerium nitrate is 2.36-3.03:2.19-2.52:0.47-0.61:4.72-6.06:0.9-2.7.

In the step (1), the heating temperature is 50°C.

In the step (2), the molecular weight of PVP is 1.3×10 ⁶ , and the concentration of PVP in the spinning precursor solution is 0.1-0.15 g/mL.

In the step (2), the heating temperature is 80°C.

In the step (3), the working temperature of the electrospinning is controlled at 20-30°C, the working humidity is controlled at 40-50%RH, the voltage of the electrospinning is 17-25kV, and the vertical distance between the spinning needle and the drum is The injection speed of the needle solution is 0.3-0.5 ml/hour, and the collection speed of the drum is 100-300 rpm.

In the step (4), the composite nanofiber precursor is kept at 70°C~80°C for 2~3 hours, the temperature is raised to 400~500°C at a rate of 2~5°C/min, and the temperature is kept at 400~500°C for 2 hours. For ~3 hours, heat up to 950°C at a rate of 2-5°C/min, and hold at 950°C for 2-3 hours to obtain BaGd _0.8 La _0.2 Co ₂ O ₅ /Gd _0.1 Ce _0.9 O _1.95 composite nanofibers.

The beneficial effects of the present invention are:

(1) The present invention uses an electrospinning instrument to prepare BGLC/GDC composite nanofibers in one step, which are used to prepare cathode materials for solid oxide batteries. In the preparation stage of the precursor solution, the elements can be mixed uniformly at the microscopic scale, and the element content can be easily regulated. At the same time, GDC particles in composite nanofibers can inhibit the growth of BGLC particles, resulting in smaller fiber diameters, only about 100-200 nm, and lengths reaching tens of microns. The prepared BGLC/GDC composite nanofibers have a higher specific surface area, which can provide more reaction sites for the cathode and make the battery have better electrochemical performance.

(2) The equipment and chemical reagents used in the present invention are easy to obtain, the process is easy to operate, the process conditions are simple, the applicability is strong, the preparation method is simple and effective, the industrial application value is high, and it is easy to popularize and utilize. It has great potential in the field of fuel cell cathode material preparation. Wide application prospects.

Description of drawings

Fig. 1 is the X-ray diffraction figure of the BGLC/GDC composite nanofiber prepared by embodiment 1-3;

Fig. 2 is the scanning electron micrograph of the BGLC/GDC composite nanofiber prepared by embodiment 1-3;

Fig. 3 is a diagram of the electrochemical performance in SOFC mode after the BGLC/GDC composite nanofiber prepared in Example 1 is prepared as a cathode.

Detailed ways

In order to make the content of the present invention easier to understand, the technical solutions of the present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited thereto.

Embodiment 1: the preparation of fiber

(1) Weigh 10ml of DMF solvent, add barium nitrate, gadolinium nitrate, lanthanum nitrate, cobalt nitrate and cerium nitrate according to the molar ratio of BaGd _0.8 La _0.2 Co ₂ O ₅ : Gd _0.1 Ce _0.9 O _1.95 =3.03:1, Stir magnetically at 50°C for 2 hours until the metal nitrate is completely dissolved in the DMF solvent to obtain a uniformly mixed precursor solution.

(2) Slowly add 1g of PVP powder into the uniformly mixed precursor solution, and magnetically stir the chamber at 80°C for 12 hours to obtain a clear and uniform precursor solution with a certain viscosity.

(3) Ultrasonic vibrate the precursor solution for 5 minutes and let it stand for 10 minutes to remove air bubbles. Use a needle tube to draw 10ml of BGLC precursor solution from the beaker, and fix the needle tube on the syringe pump of the electrospinning instrument; adjust the electrospinning instrument The voltage parameter is 20kV; the collection speed of the drum is 200 rpm; the vertical distance between the needle and the drum is set to 15 cm; the injection speed of the needle is set to 0.4 ml/hour; electrospinning is performed after the parameters are set.

(4) Calcinate the spun BGLC/GDC nanofiber precursor at high temperature, keep it at 80°C for 2 hours, raise the temperature to 500°C at a heating rate of 2°C/min, and keep it at 500°C for 2 hours. The temperature was raised to 950°C at a rate of 2°C/min, kept at 950°C for 3 hours, cooled to 500°C at a rate of 5°C/min, and then naturally cooled to room temperature to obtain BGLC/GDC composite nanofibers.

Embodiment 2: the preparation of fiber

(1) Weigh 10ml DMF solvent, add barium nitrate, gadolinium nitrate, lanthanum nitrate, cobalt nitrate and cerium nitrate according to the molar ratio of BaGd _0.8 La _0.2 Co ₂ O ₅ : Gd _0.1 Ce _0.9 O _1.95 =2.7:2, Stir magnetically at 50°C for 2 hours until the metal nitrate is completely dissolved in the DMF solvent to obtain a uniformly mixed precursor solution.

(2) Slowly add 1g of PVP powder into the uniformly mixed precursor solution, and magnetically stir the chamber at 80°C for 12 hours to obtain a clear and uniform precursor solution with a certain viscosity.

(3) Ultrasonic vibrate the precursor solution for 5 minutes and let it stand for 10 minutes to remove air bubbles. Use a needle tube to draw 10ml of BGLC precursor solution from the beaker, and fix the needle tube on the syringe pump of the electrospinning instrument; adjust the electrospinning instrument The voltage parameter is 20kV; the collection speed of the drum is 200 rpm; the vertical distance between the needle and the drum is set to 15 cm; the injection speed of the needle is set to 0.4 ml/hour; electrospinning is performed after the parameters are set.

(4) Calcinate the spun BGLC/GDC nanofiber precursor at high temperature, keep it at 80°C for 2 hours, raise the temperature to 500°C at a heating rate of 2°C/min, and keep it at 500°C for 2 hours. The temperature was raised to 950°C at a rate of 2°C/min, kept at 950°C for 3 hours, cooled to 500°C at a rate of 5°C/min, and then naturally cooled to room temperature to obtain BGLC/GDC composite nanofibers.

Embodiment 3: the preparation of fiber

(1) Weigh 10ml of DMF solvent, add barium nitrate, gadolinium nitrate, lanthanum nitrate, cobalt nitrate and cerium nitrate according to the molar ratio of BaGd _0.8 La _0.2 Co ₂ O ₅ : Gd _0.1 Ce _0.9 O _1.95 =2.36:3, Stir magnetically at 50°C for 2 hours until the metal nitrate is completely dissolved in the DMF solvent to obtain a uniformly mixed precursor solution.

(2) Slowly add 1g of PVP powder into the uniformly mixed precursor solution, and magnetically stir the chamber at 80°C for 12 hours to obtain a clear and uniform precursor solution with a certain viscosity.

(3) Ultrasonic vibrate the precursor solution for 5 minutes and let it stand for 10 minutes to remove air bubbles. Use a needle tube to draw 10ml of BGLC precursor solution from the beaker, and fix the needle tube on the syringe pump of the electrospinning instrument; adjust the electrospinning instrument The voltage parameter is 20kV; the collection speed of the drum is 200 rpm; the vertical distance between the needle and the drum is set to 15 cm; the injection speed of the needle is set to 0.4 ml/hour; electrospinning is performed after the parameters are set.

(4) Calcinate the spun BGLC/GDC nanofiber precursor at high temperature, keep it at 80°C for 2 hours, raise the temperature to 500°C at a heating rate of 2°C/min, and keep it at 500°C for 2 hours. The temperature was raised to 950°C at a rate of 2°C/min, kept at 950°C for 3 hours, cooled to 500°C at a rate of 5°C/min, and then naturally cooled to room temperature to obtain BGLC/GDC composite nanofibers.

Performance Characterization:

Figure 1 is the XRD diffraction patterns of BGLC/GDC composite nanofibers with different GDC contents prepared in Examples 1-3. At the calcination temperature of 950 °C, sharp BGLC and GDC diffraction peaks can be observed, and no other impurity crystal phases appear, indicating that the crystallinity of BGLC and GDC in BGLC/GDC composite nanofibers is good, and no impurity phases are formed. And with the increase of GDC content, the peak intensity of GDC diffraction peaks gradually increased, indicating that the content of GDC is controllable when preparing BGLC/GDC composite nanofibers.

Figure 2 is the scanning electron micrographs of BGLC/GDC composite nanofibers with different GDC contents prepared in Examples 1-3. Figure (a) The molar ratio of BGLC to GDC is 3.03:1, and the average fiber diameter is about 210nm. The specific surface area of the fiber is 7.07 m ² ·g ^-1 , and Figure (d) is a partial enlarged view of Figure (a); Figure (b) has a molar ratio of BGLC to GDC of 2.7:2, and the average fiber diameter is about 180nm. The specific surface area is 7.14 m ² ·g ^-1 ; (c) the molar ratio of BGLC to GDC is 2.36:3, the average fiber diameter is about 110nm, and the specific surface area of the fiber is 8.62 m ² ·g ^-1 . It can be seen from the figure that different GDC contents can form a BGLC/GDC composite nanofiber structure with good shape, and the fibers overlap each other to form a three-dimensional network structure. The fibers have a large porosity and a large specific surface area. And with the increase of GDC content, the average diameter of BGLC/GDC composite nanofibers decreased obviously, and the specific surface area gradually increased.

Fig. 3 is a diagram of the electrochemical performance in SOFC mode after the BGLC/GDC composite nanofiber prepared in Example 1 is prepared as a cathode. Its maximum power density at 800°C is 0.86W·cm ^-2 . It can be seen from the figure that the BGLC/GDC composite nanofiber cathode has good electrochemical performance at medium and high temperatures.

The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims (8)

1. A solid oxide cell composite nanofiber, characterized by: chemical composition of BaGd _0.8 La _0.2 Co ₂ O ₅ /Gd _0.1 Ce _0.9 O _1.95 ；

The preparation method comprises the following steps:

(1) Dissolving barium nitrate, gadolinium nitrate, lanthanum nitrate, cobalt nitrate and cerium nitrate in DMF, stirring to completely dissolve nitrate, and obtaining nitrate-DMF solution;

(2) PVP is added into the nitrate-DMF solution, and stirring is carried out until the PVP is completely dissolved, so as to obtain spinning precursor solution;

(3) Carrying out ultrasonic oscillation on the spinning precursor solution, standing until bubbles are completely removed, and carrying out electrostatic spinning to obtain a composite nanofiber precursor;

(4) Calcining the composite nanofiber precursor in a heat-preserving way to obtain the composite nanofiber BaGd _0.8 La _0.2 Co ₂ O ₅ /Gd _0.1 Ce _0.9 O _1.95 ；

In the step (1), the molar ratio of barium nitrate, gadolinium nitrate, lanthanum nitrate, cobalt nitrate and cerium nitrate is 2.36-3.03: 2.19-2.52: 0.47 to 0.61:4.72 to 6.06:0.9 to 2.7.

2. The solid oxide cell composite nanofiber according to claim 1, wherein: in the step (1), the total mass of the barium nitrate, the gadolinium nitrate, the lanthanum nitrate, the cobalt nitrate and the cerium nitrate is 10% -15% of the mass of the DMF solvent.

3. The solid oxide cell composite nanofiber according to claim 1, wherein: the heating temperature in the step (1) is 50 ℃.

4. The solid oxide cell composite nanofiber according to claim 1, wherein: PVP in step (2) has a molecular weight of 1.3X10 ⁶ The concentration of PVP in the spinning precursor solution is 0.1-0.15 g/mL.

5. The solid oxide cell composite nanofiber according to claim 1, wherein: the heating temperature in the step (2) is 80 ℃.

6. The solid oxide cell composite nanofiber according to claim 1, wherein: in the step (3), the working temperature of electrostatic spinning is 20-30 ℃, the working humidity is 40-50% RH, the working voltage is 17-25kV, the vertical distance between a spinning needle and a rotary drum is 12-18 cm, the injection speed of a needle solution is 0.3-0.5 ml/h, and the collection speed of the rotary drum is 100-300 r/min.

7. The solid oxide cell composite nanofiber according to claim 1, wherein: the specific process of heat preservation and calcination in the step (4) comprises the following steps: and (3) preserving heat for 2-3 hours at 70-80 ℃, heating to 400-500 ℃ at the speed of 2-5 ℃/min, preserving heat for 2-3 hours, heating to 950 ℃ at the speed of 2-5 ℃/min, and preserving heat for 2-3 hours.

8. Use of the composite nanofiber according to claim 1 in a solid oxide cell cathode material.

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