CN105742658B - The preparation method of electrode material for all-vanadium flow battery - Google Patents

Abstract

The invention relates to a preparation method of an electrode material for a liquid flow battery, in particular to a preparation method for an electrode material for an all-vanadium redox flow battery. The realization process of the method is: immerse the carbon material into a certain concentration of nitrogen-containing raw materials, obtain a precursor of the target electrode through ultrasonic and drying treatment, and then carbonize the above precursor at high temperature to obtain the target electrode. The nitrogen-containing functional groups on the surface of the modified electrode material have been greatly improved, and its electrochemical activity and conductivity have been improved, reducing the reaction internal resistance of the electrode used in the all-vanadium redox flow battery, and at the same time increasing the electrode's contact with the electrode. The reactive active sites of the electrolyte greatly improve the voltage efficiency and energy efficiency of the all-vanadium redox flow battery. The electrode preparation process of the invention is simple, the raw material is easy to obtain, the cost is low, the performance is stable and mass production can be carried out.

Description

Preparation method of electrode material for all-vanadium redox flow battery

technical field

The invention relates to a preparation method of an electrode material for a liquid flow battery, in particular to a preparation method for an electrode material for an all-vanadium redox flow battery.

Background technique

Due to its flexible system design, relatively independent output power and capacity, the flow battery has a long service life, can be charged and discharged with a large current, and has stable overall performance. Flow batteries, especially all-vanadium flow batteries, are considered to be an effective method to solve intermittent and unstable power resources such as solar and wind energy.

Since M.Skyllas-kazacos et al. began to study the all-vanadium redox flow battery in 1985, the all-vanadium redox flow battery has been greatly developed. It uses VO ₂ ⁺ /VO ²⁺ and V ²⁺ /V ³⁺ redox The electrode pair is used as positive and negative electrodes respectively in sulfuric acid solution, and exhibits electrochemical characteristics such as wide open circuit voltage and deep discharge. Typical materials used in all-vanadium redox flow batteries are some carbon materials: including carbon felt, carbon cloth and graphite felt. This type of material has the advantages of wide operating voltage window, large specific surface area, good stability and reasonable price. However, the above-mentioned carbon-based materials have problems such as low electrochemical activity and poor reversibility of reaction kinetics.

In order to improve the electrochemical activity of the above materials, a lot of research has been done on their modification at home and abroad. Including: heat treatment, acid treatment and precious metal modification and other methods. The heat treatment process is complicated, and the oxidation process is difficult to control. Excessive oxidation will reduce the service life and stability of the electrode material. Acid treatment mainly uses concentrated sulfuric acid and concentrated nitric acid to treat electrode materials for a long time. The energy efficiency of all-vanadium redox flow batteries has been greatly improved, but a large amount of waste acid is produced after treatment, which causes great pollution to the environment. Noble metal modification is difficult to prepare on a large scale due to the need for sintering and the complicated process and high cost.

Graphite carbon nitride has been extensively studied as a metal-free catalyst and catalyst support in recent years because of its excellent chemical stability and unique electronic structure. Significant progress has been made in photocatalytic water splitting, oxygen reduction, as green energy storage materials and hard templating agents for _H2 and _CO2 storage.

Contents of the invention

The purpose of the present invention is to solve the problem of low activity and poor reaction kinetic reversibility of the above-mentioned all-vanadium redox flow battery electrode materials, and propose a modification method for all-vanadium redox flow battery electrodes. The electrode preparation process is simple and the cost is low. , for industrial mass production.

In order to achieve the above object, the technical solution adopted in the present invention is: a preparation method of an electrode material for an all-vanadium redox flow battery, which comprises the following steps:

(1) Immerse the carbonaceous material in the solution of nitrogen-containing raw materials for ultrasonic treatment for 5~40min;

(2) Dry the carbonaceous material treated in step (1) in an oven at a drying temperature of 80-120°C and a drying time of 8-16 hours to obtain the precursor of the target electrode;

(3) Place the precursor of the target electrode obtained in step (2) into a tube furnace or muffle furnace for carbonization. The carbonization temperature is 450~600°C, and the heating rate is 3~8°C/min. After the temperature rises to the carbonization temperature After heat preservation for 1-6 hours, the target electrode material for all-vanadium redox flow battery modified by graphite phase carbon nitride can be obtained.

In the above solution, the nitrogen-containing raw materials are materials such as urea, melamine or cyanamide, preferably urea solution.

In the above solution, the carbonaceous material is carbon felt, carbon cloth, carbon paper or graphite felt, preferably graphite felt.

In the above scheme, the solution concentration of the nitrogen-containing raw materials is 0.001-1 g/ml.

In the above scheme, the solvent of the nitrogen-containing raw material solution is deionized water.

In the above scheme, the ultrasonic treatment time in step (1) is preferably 15 minutes.

In the above scheme, the drying temperature in step (2) is preferably 100°C.

In the above solution, the carbonization temperature in the tube furnace or muffle furnace in step (3) is preferably 550°C.

In the above scheme, the holding time in the tube furnace or muffle furnace in step (3) is preferably 1 h.

The present invention grows graphite phase carbon nitride in situ on the surface of the target electrode through high temperature carbonization, because graphite phase carbon nitride contains rich quaternary nitrogen structure, quaternary nitrogen is relatively stable in acidic environment, and due to the electronegativity of nitrogen It is easy to adsorb vanadium ions to form a nitrogen-vanadium transition state, which facilitates the transport of ions and the transfer of charges, thereby improving the electrochemical activity of the electrode material of the all-vanadium redox flow battery and increasing the voltage of the all-vanadium redox flow battery efficiency and energy efficiency.

The present invention has the following advantages:

(1) The electrode material prepared by the present invention increases the nitrogen-containing functional groups on the surface of the electrode due to the modification of the graphite phase carbon nitride, introduces more reactive sites, and improves the electrocatalytic activity and the reversibility of the reaction kinetics.

(2) The electrode material prepared by the present invention improves the hydrophilicity of carbon materials (carbon felt, carbon cloth, carbon paper or graphite felt, etc.) due to the increase of nitrogen-containing functional groups on the electrode surface, and increases the conductivity of the electrode material. performance, thereby improving the energy efficiency and voltage efficiency of the all-vanadium redox flow battery.

(3) The process of the present invention is simple, the raw materials are readily available, the reaction time is short, the operation is flexible and convenient, and it is easy for large-scale production.

Description of drawings

Fig. ¹ is the graphite felt electrode modified by the present invention and the blank graphite felt electrode under 100 mA/cm Current density charge and discharge curve figure, as can be seen from the figure, the present invention utilizes the graphite felt electrode modified by graphite phase carbon nitride It has very excellent electrochemical performance.

Fig. 2 is the graphite felt electrode modified by the present invention and the blank graphite felt electrode under 150 mA/cm Current density charge ^- discharge graph, as can be seen from the figure, the prepared electrode of the present invention is relative to The blank felt showed good electrochemical performance.

Fig. 3 is a scanning electron microscope comparison between the graphite felt of the blank group and the graphite felt modified by the graphite phase carbon nitride of the present invention, showing that the graphite oxide phase carbon nitride is successfully loaded on the surface of the graphite felt fiber.

detailed description

The present invention is described in detail below by specific examples.

Implementation example one:

Take 4g of melamine and dissolve it in 50ml of deionized water, stir and dissolve in a beaker, place a certain area of graphite felt electrode in the solution, and make it completely submerged. Then, put the beaker into an ultrasonic instrument for ultrasonic treatment, and the ultrasonic time is 10 minutes, so that the melamine solution is uniformly dispersed in the graphite felt electrode. Subsequently, the graphite felt electrode was taken out, placed on an evaporating dish, and dried in an oven at a drying temperature of 80° C. and a drying time of 14 hours to obtain the target electrode precursor. Then, put the target electrode precursor into a tube furnace for carbonization at a heating rate of 4°C/min, wait for the temperature to rise to 550°C, and keep it warm for 3 hours to obtain the electrode material for the all-vanadium redox flow battery. In order to test the electrochemical performance of the electrode, the battery assembled with the electrode was charged and discharged. At a current density of 50mA/cm ² , the voltage efficiency of the all-vanadium redox flow battery was 89.7%, and the energy efficiency was 88.3%.

Implementation example two:

Dissolve 6g of urea in 50ml of deionized water, stir and dissolve in a beaker, place a certain area of graphite felt electrode in the solution, and make it completely submerged. Then, the beaker was put into an ultrasonic instrument for ultrasonic treatment, and the ultrasonic time was 15 minutes, so that the urea solution was uniformly dispersed in the graphite felt electrode. Subsequently, the graphite felt electrode was taken out, placed on an evaporating dish, and dried in an oven at a drying temperature of 100° C. and a drying time of 12 hours to obtain the target electrode precursor. Then, put the target electrode precursor into a tube furnace for carbonization at a heating rate of 5°C/min, wait for the temperature to rise to 550°C, and keep it warm for 2 hours to obtain an electrode material for an all-vanadium redox flow battery. In order to test the electrochemical performance of the electrode, the battery assembled with the electrode was charged and discharged. Under the current density of 100mA/cm ² , the voltage efficiency of the all-vanadium redox flow battery was 80.2%, and the energy efficiency was 78.3%.

Implementation example three:

Dissolve 10g of urea in 50ml of deionized water, stir and dissolve in a beaker, place a certain area of carbon felt electrode in the solution, and make it completely submerged. Then, the beaker was put into an ultrasonic instrument for ultrasonic treatment, and the ultrasonic time was 15 minutes, so that the urea solution was uniformly dispersed in the carbon felt electrode. Subsequently, the carbon felt electrode was taken out, placed on an evaporating dish, and dried in an oven at a drying temperature of 120° C. and a drying time of 10 h to obtain the target electrode precursor. Then, put the target electrode precursor into a tube furnace for carbonization at a heating rate of 6°C/min, wait for the temperature to rise to 550°C, and keep it warm for 1 hour to obtain the electrode material for the all-vanadium redox flow battery. In order to test the electrochemical performance of the electrode, the battery assembled with the electrode was charged and discharged. At a current density of 120mA/cm ² , the voltage efficiency of the all-vanadium redox flow battery was 75.1%, and the energy efficiency was 74.2%.

Implementation example four:

Take 10g of melamine and dissolve it in 50ml of deionized water, stir and dissolve in a beaker, place a certain area of carbon felt electrode in the solution, and make it completely submerged. Then, the beaker was placed in an ultrasonic instrument for ultrasonic treatment, and the ultrasonic time was 20 min, so that the urea solution was uniformly dispersed in the carbon felt electrode. Subsequently, the carbon felt electrode was taken out, placed on an evaporating dish, and dried in an oven at a drying temperature of 120° C. and a drying time of 10 h to obtain the target electrode precursor. Then, put the target electrode precursor into a tube furnace for carbonization at a heating rate of 4°C/min, wait for the temperature to rise to 500°C, and keep it warm for 2 hours to obtain an electrode material for an all-vanadium redox flow battery. In order to test the electrochemical performance of the electrode, the battery assembled with the electrode was charged and discharged. Under the current density of 150mA/cm ² , the voltage efficiency of the all-vanadium redox flow battery was 66.8%, and the energy efficiency was 65.6%.

Claims (7)

1. a kind of preparation method of electrode material for all-vanadium flow battery, it is characterised in that comprise the following steps：

(1) ultrasonically treated 5~40min is carried out in the solution that carbon class material is immersed nitrogenous class raw material, wherein, described is nitrogenous Class raw material is urea, melamine or cyanamide, and the solvent of the solution of the nitrogenous class raw material is deionized water；

(2) the carbon class material processed through step (1) is put and dries in an oven, drying temperature is 80~120 DEG C, drying time 8~16h, obtains the presoma of target electrode；

(3) it is carbonized in the presoma of gained target electrode in step (2) being placed in into tube furnace or Muffle furnace, carburizing temperature is 450 ~600 DEG C, 3~8 DEG C/min of heating rate, temperature is incubated 1~6h after being raised to carburizing temperature, that is, obtain graphite phase carbon nitride modification Target electrode material used for all-vanadium redox flow battery.

2. the preparation method of electrode material for all-vanadium flow battery as claimed in claim 1, it is characterised in that：The carbon class Material is carbon felt, carbon cloth, carbon paper or graphite felt.

3. the preparation method of electrode material for all-vanadium flow battery as claimed in claim 1, it is characterised in that：The nitrogenous class The solution concentration of raw material is 0.001~1g/ml.

4. the preparation method of electrode material for all-vanadium flow battery as claimed in claim 1, it is characterised in that：In step (1) The sonication treatment time is 15min.

5. the preparation method of electrode material for all-vanadium flow battery as claimed in claim 1, it is characterised in that：In step (2) The drying temperature is 100 DEG C.

6. the preparation method of electrode material for all-vanadium flow battery as claimed in claim 1, it is characterised in that：In step (3) The carburizing temperature in tube furnace or in Muffle furnace is 550 DEG C.

7. the preparation method of electrode material for all-vanadium flow battery as claimed in claim 1, it is characterised in that：In step (3) The soaking time in tube furnace or in Muffle furnace is 1h.