Vanadium battery is a new type of energy storage battery developed in recent years, because of its high energy efficiency and long service life.

　　Environmental friendly and cheap, operating and maintenance costs low, many of the characteristics of the rapid development of. But at present, there are some problems in vanadium battery. There are many factors that affect the performance of vanadium battery, including the electrode material performance, the positive and negative electrode reaction is an important factor.

　　Graphite felt has a series of excellent properties, such as high specific strength, high specific modulus, high temperature resistance, corrosion resistance, conductivity and thermal expansion coefficient, so it is used in the field of vanadium battery. However, it is found that the active surface area is smaller than the surface area, the surface energy is low, and the wettability is poor.

　　By low temperature liquid phase oxidation method for surface oxidation of graphite felt, with different concentration and Potassium Permanganate solution at different temperature and acid solution on Potassium Permanganate graphite felt for processing, to obtain the performance of graphite felt electrode material excellent. The graphite felt surface becomes smooth after Potassium Permanganate solution treatment.

　　The surface polar groups of the graphite felt treated by different Potassium Permanganate solution increased, and the hydrophilicity was improved. Graphite felt on the surface in the process of Potassium Permanganate solution deposition on the Potassium Permanganate, is not conducive to V (IV) in the above reaction.

　　Another way to improve the activity of graphite felt is to deposit metal or metal oxide on the surface of graphite felt. Transition metal oxide or semiconductor compound.

　　The graphite felt electrode used for vanadium redox flow battery was used in the electrochemical treatment, the activity of the electrode was improved, the voltage efficiency was increased, and the current efficiency was improved. After electrochemical treatment, the O/C ratio of graphite felt surface increases, and the main increase is COOH functional group.

　　The analysis results show that the surface of carbon fiber is etched, and the specific surface area is increased. The increase of the electrode activity is attributed to the increase of the number of COOH functional groups on the surface of carbon fiber and the increase of specific surface area.

　　The small capacity of the battery has been successfully applied in human life, further research and development of new environmentally friendly battery suitable for large-scale energy storage, development and utilization of new energy sources, will have great social and economic significance.

　　All vanadium redox flow battery can be regarded as the representative of the new energy storage battery, compared with other batteries, it has a unique advantage, and has been the attention of scientists at home and abroad, at present, the vanadium battery has been abroad applied to wind power plant, peak load regulation of power grid and solar photovoltaic power station demonstration operation. However, the development of vanadium battery is still limited, and the electrode material is a very important factor.

　　The electrode material is mainly divided into metal electrode and carbon electrode, wherein the carbon electrode with good stability reflects the greater advantage, and the carbon electrode, graphite felt materials with its advantages of real surface area is much larger than the geometric surface area and occupies the dominant position, the graphite felt were activated by concentrated sulfuric acid by liquid phase oxidation and air oxidation method, that can greatly improve the electrochemical performance of vanadium battery.

　　Although the process is simple, the process is simple, the operation is small, and the oxidation reaction is not easy to control. Concentrated sulfuric acid oxidation process is very dangerous, industrial production is very difficult. The electrochemical oxidation method, which is easy to control, easy to control, and easy to realize industrialized operation, is easy to control.

　　All vanadium redox flow battery (VRB battery, VRB) is a new type of green environmental protection battery, has the advantages of high efficiency, long service life, safe and reliable, can be used as a large energy storage device, the wind, hydro, solar and other unstable energy into electrical energy storage to be used as a backup power supply has a wide application prospect.

　　The hydrophilic and electrochemical activity of PAN based (PAN) graphite felt is poor and the graphite felt needs to be modified to be better used in vanadium battery. In order to improve the electrochemical activity of graphite felt, the two cerium oxide was modified on graphite felt by ethanol solution method and sol gel method. Two cerium oxide has the capability of storing and releasing oxygen and the diffusion capacity of fast oxygen vacancies, which is the most active catalyst in rare earth oxides.

　　Modified graphite felt, in the battery testing of the highest coulomb efficiency can reach 95%, energy efficiency is also close to 90%.Surface deposition method on the surface of graphite felt with catalytic activity of metal, is another kind of modified graphite felt. On the surface of graphite felt were introduced into manganese, cobalt and nickel three metals, and physical and electrochemical properties test of modified graphite felt. The results showed that the modified surface of graphite fiber functional changes, wettability of graphite felt, to improve its electrochemical activity. Battery test results show that the coulomb efficiency can reach 90%.

　　Graphite felt is a great ratio of carbon fiber surface area, can provide a larger electrochemical reaction for the electrochemical reaction, while the graphite felt has strong oxidation and corrosion resistance, and in addition to the conductive properties of itself, because the graphite felt electrode can be compressed, as battery assembly, contact resistance and bipolar in the small, compared with the metal electrode, the cost is relatively low, is a kind of ideal electrode material.

　　According to the change of the surface wettability of graphite felt, the operation conditions of Shi Mozhan's treatment were determined. The graphite felt acid treated with nitric acid treated as an electrode material, the surface wettability of graphite felt significantly increased after acidification treatment, the surface contact angle decreased with graphite felt, graphite felt nitric acid is used as electrode material, current output increased and stable.

　　Microbial fuel cell is a microbial as the anode catalyst, can be directly in the water samples can be degraded organic compounds of chemical energy into electrical energy.

　　The performance of anode material usually directly affects the rate of electron transfer and mass transfer, and then affects the performance of the sensor.

　　Graphite felt has good conductivity, large surface area, high mechanical strength, so often used as anode materials, electrochemical activity but Shi Mozhan often fail to use electrode material requirements, mainly for microbial adhesion is weak, the modification is the main method to improve the activity of carbon materials, the hydrophilicity of the material surface the greatly improved after treatment to mass transfer of microbial growth and substrate adsorption.

　　Commonly used carbon materials modification methods include acid treatment "heat treatment" electrochemical oxidation treatment and ammonia treatment, acid treatment with convenient operation, good effect and so on.

　　The wettability of graphite felt surface affects the adsorption of cells on the surface of the surface and the mass transfer capability, the contact angle is generally used to indicate that the smaller the contact angle, the better the wettability of the material.

　　Nitric acid treatment improved the wettability of graphite felt, and promoted the adhesion of microorganisms on the surface of the surface, so that the rapid growth of microorganisms in the graphite felt electrode enrichment, the formation of a stable biofilm.

　　The small capacity of the battery has been successfully applied in human life, further research and development of new environmentally friendly battery suitable for large-scale energy storage, development and utilization of new energy sources, will have great social and economic significance. All vanadium redox flow battery can be regarded as the representative of the new energy storage battery, compared with other batteries and it has a unique advantage, and therefore by researchers at home and abroad. At present, the vanadium battery has been abroad applied to wind power plant, power station power peaking and solar photovoltaic demonstration operation. But the development of vanadium battery is still limited, the electrode material is a very important factor.

　　The electrode material is mainly divided into metal electrode and carbon electrode, wherein the carbon electrode with good stability reflects the greater advantage, and the carbon electrode, graphite felt materials with its advantages of real surface area is much larger than the geometric surface area and occupies the dominant position.

　　Using concentrated sulfuric acid liquid phase oxidation and air oxidation method to activate the graphite felt, it was found that the electrochemical performance of the graphite felt can be greatly improved.

　　The surface treatment of graphite felt electrode for vanadium battery was carried out by electrochemical oxidation method, and the charge discharge performance of the assembled battery was excellent.

　　The main change of electrochemical treatment is the ratio of O/C and the number of oxygen containing functional groups on the carbon fiber surface of graphite felt,especially the amount of COOH.

　　Treated graphite felt as electrode, the battery showed good charge and discharge performance.

　　Electrode material is one of the key materials for all vanadium redox flow battery. Graphite felt material due to the large real surface area, good stability and occupy the leading position. But the graphite felt material is poor in hydrophilicity, and the electrochemical activity is not good enough. This paper on the graphite felt electrode respectively chromic acid oxidation method, mixed acid electrochemical oxidation method and hydrothermal ammoniation method for processing vanadium redox flow battery to improve its activity.

　　The chromic acid oxidation, hydrophilicity and electrochemical activity of graphite felt electrode significantly enhanced, The increase of oxygen functional groups on the carbon fiber and the surface gully increased, the former increased the carbon fiber surface to participate in the VO2+/VO2+ electrode reaction, which increased the contact area of vanadium ion and electrode.

　　Compared with other chemical power supply, vanadium battery has obvious advantages, the main advantages are as follows:

　　1 power: by increasing the number of single cell and electrode area, you can increase the power of the vanadium battery, the current U.S. commercial demonstration of the power of the vanadium battery has reached 6MW.

　　2 large capacity: increase the volume or improve the vanadium electrolyte concentration can increase consumption, up to more than gwh.

　　3 high efficiency: because the electrode catalytic activity of vanadium battery is high, and the positive and negative active substances are stored in positive and negative electrolyte tank, self discharge consumption, energy conversion efficiency as high as 75%, far higher than the lead-acid battery.

　　In a lot of electrode materials, carbon electrode has a great advantage in its good stability, and the graphite felt material is dominant in the real surface area. But the graphite felt surface activity is not good, poor hydrophilicity; commercial graphite felt, the conductive properties of imported graphite felt good, graphitization degree is high, but the price is expensive; graphite felt while the cost is low, but the degree of graphitization of low conductivity is poor.

　　In the global energy crisis and environmental pollution under the background of governments on the development and utilization of key technology and energy related very seriously, new energy countries vigorously develop clean and renewable energy to reduce the traditional. To develop new energy resources, energy storage is the key. With the application of new energy sources such as solar energy and wind energy, the research of new energy storage technology with high efficiency, long life and low cost is especially important.

　　The graphite felt electrode was modified by the method of constant current step activation, and the high performance carbon electrode material was prepared.

　　As the graphite felt has the advantages of high surface area, good chemical stability, low price, good conductivity, electrode materials have been widely used in electrochemical capacitor and redox flow battery of these large energy storage devices.

　　But the surface of the carbon material operation on the surface of microporous electrode directly, containing hydrophilic group is relatively small, and most of them are hydrophobic organic groups of water, so the surface wettability is poor, difficult to penetrate into the surface of the electrode electrolyte, not easy to form electric double layer, the carbon materials can not achieve the theory specific capacitance value.

　　It is found that the carbon material after several physical and chemical methods of surface modification, will generate some oxygen containing functional groups, the increase of material wettability, increase the effective surface area, and increase the specific capacitance of carbon materials. Therefore, research on surface modification of carbon materials to carry out a large number of methods, scholars at home and abroad are mainly used in gas phase oxidation, liquid phase oxidation, anodic oxidation, plasma oxidation, microwave oxidation etc..

　　All vanadium redox flow battery (VRB battery, VRB) is a new type of green environmental protection battery, has the advantages of high efficiency, long service life, safe and reliable, can be used as a large energy storage device, the wind, hydro, solar and other unstable energy into electrical energy storage to be used as a backup power supply has a wide application prospect. The hydrophilic and electrochemical activity of PAN based (PAN) graphite felt is poor and the graphite felt needs to be modified to be better used in vanadium battery.

　　In order to improve the electrochemical activity of graphite felt, the two cerium oxide was modified on graphite felt by ethanol solution method and sol gel method. Modified graphite felt, in the battery testing of the highest coulomb efficiency can reach 95%, energy efficiency is also close to 90%. Surface deposition method on the surface of graphite felt with catalytic activity of metal, is another kind of modified graphite felt. Battery test results show that the coulomb efficiency can reach 90%.

　　Polyacrylonitrile (PAN) graphite felt is a great ratio of carbon fiber surface area, can provide a larger electrochemical reaction for the electrochemical reaction, while the graphite felt has strong oxidation and corrosion resistance, and in addition to the conductive properties of itself, because the graphite felt electrode can be compressed, as the battery assembly, the contact resistance and the bipolar plate is small, compared with the metal electrode, the cost is relatively low, is a kind of ideal electrode material. But to be used as electrode materials for vanadium battery, large scale application in the actual production, life, but also to solve the problem of poor Shi Mozhan hydrophilic and electrochemical activity.

　　The activity of graphite felt electrode can be improved by electrochemical treatment, the increase of the electrode activity is attributed to the increase in the number of functional groups on the surface of carbon fiber and the increase of the specific surface area of the COOH.

　　The small capacity of the battery has been successfully applied in human life, further research and development of new environmentally friendly battery suitable for large-scale energy storage, development and utilization of new energy sources, will have great social and economic significance. All vanadium redox flow battery can be regarded as the representative of the new energy storage battery, compared with other batteries it has a unique advantage.

　　At present, the vanadium battery has been abroad applied to wind power plant, power station power peaking and solar photovoltaic demonstration operation. But the development of vanadium battery is still limited, the electrode material is a very important factor.

　　The electrode material is mainly divided into metal electrode and carbon electrode, wherein the carbon electrode with good stability reflects the greater advantage, and the carbon electrode, graphite felt materials with its advantages of real surface area is much larger than the geometric surface area and occupies the dominant position.

　　Using concentrated sulfuric acid liquid phase oxidation and air oxidation method to activate the graphite felt, it was found that the electrochemical performance of the graphite felt can be greatly improved,although the process is simple, the process is simple, the operation is small, and the oxidation reaction is not easy to control.

　　The surface treatment of graphite felt by electrochemical oxidation, electrochemical performance of vanadium battery in the graphite felt electrode before and after treatment were investigated, which were characterized by FT-IR, SEM, BET and XPS, and improve the activity of the preliminary analysis,

　　Among all kinds of electrode materials of vanadium redox flow battery, graphite felt is the best comprehensive performance of electrode material, but it still needs to be activated to enhance its performance.

　　As one of the most important parts of vanadium battery, electrode and its related characteristics, including cost and processing technology, have become the key aspects of the research and development of vanadium battery system. Choosing appropriate electrode materials can improve the electrochemical activity of the electrode, and ultimately improve the energy efficiency of vanadium battery. Vanadium battery electrode materials are carbon, such as graphite, carbon cloth, carbon felt, etc., there are metals, such as Pb, Ti, etc., there are conductive polymer or polymer mixture composite electrode.

　　But from the point of reducing the cost of the electrode and reducing the quality of the battery, the results of the study of various carbon materials show that the effect of PAN based graphite felt is best.

　　However, the performance of PAN based graphite felt can not meet the needs of vanadium battery, and it needs to be processed on the graphite felt surface to improve its performance.

　　Although the comprehensive performance of graphite felt is superior, the electrochemical activity of the electrode can not meet the requirement of vanadium battery, so it needs to be processed to improve its electrochemical performance. Common graphite felt treatment methods are metal ion modification,acid treatment, heat treatment, ammoniation treatment, electrochemical treatment and comprehensive treatment.

　　After a variety of methods to deal with, will make graphite felt's specific surface area increased, the reaction area increased. At the same time, after treatment increased the number of carbon fiber surface active functional groups such as C=O and C-O functional groups such as the removal of the impurities on the surface of carbon fiber such as the production of metal ions was introduced into the process, reduce the resistance of graphite felt, so as to improve the electrochemical activity of graphite felt.