Preparation method of vanadium battery electrode

Abstract

The invention discloses a preparation method of a vanadium battery electrode, and belongs to the technical field of vanadium battery processing. The preparation method comprises the following steps: S1, selecting a carbon felt as a base material, and selecting nanoscale titanium dioxide and graphene as composite modified materials; s2, pretreating the carbon felt, removing impurities on the surface of the carbon felt through pretreatment, and increasing surface active sites of the carbon felt; s3, the pretreated carbon felt serves as a substrate, a spinning solution containing titanium dioxide and graphene is evenly sprayed to the surface of the carbon felt through electrostatic spinning equipment, then the carbon felt obtained after spinning is completed is put into a hot-pressing mold to be subjected to hot pressing, and an electrode primary product is obtained after hot pressing is completed; s4, the primary electrode product is put into plasma treatment equipment for plasma surface modification, and a finished electrode product is obtained; and S5, testing the conductivity, cyclic voltammetry and durability of the electrode finished product. According to the scheme, the problem that an existing vanadium battery electrode processing method is large in energy consumption is solved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of vanadium battery processing, in particular to a preparation method of a vanadium battery electrode. BACKGROUND

[0002] Vanadium battery generally refers to a full vanadium redox flow battery, which is a large-scale energy storage technology, and is particularly suitable for applications such as balancing the load of a power grid, storing renewable energy (such as wind energy and solar energy), and providing uninterrupted power supply. The selection of the electrode material of the vanadium battery is crucial to the performance of the battery.

[0003] In the patent with the application number 202411176732.6, a full vanadium flow battery electrode and a preparation method thereof are disclosed. The method comprises the following steps: oxidation: oxidizing polyacrylonitrile graphite felt in an oxygen atmosphere to obtain a base electrode; mixing: uniformly mixing carbon aerogel, carbon black and polyvinyl alcohol solution to obtain a mixed solution; impregnation: impregnating the base electrode in the mixed solution, then taking it out and drying to obtain an impregnated electrode; carbonization: carbonizing the impregnated electrode to obtain a carbonized electrode; drying: washing and drying the carbonized electrode to obtain a full vanadium flow battery electrode. The application uses polyvinyl alcohol as an adhesive and carbonization treatment, which helps the carbon aerogel and carbon black to be adsorbed on the oxidized polyacrylonitrile graphite felt, improving the conductivity and adhesion stability. The full vanadium flow battery electrode of the application is superior to the full vanadium flow battery electrode produced by carbon nanotubes, and the cost is reduced. In the patent, the carbonization step is carried out at a high temperature of 900-1000℃, and the time is 2-4 hours. When oxidizing, the oxidation temperature is 550-600℃, and the oxidation time is 2-4 hours. Such a high temperature requirement will consume a large amount of energy, thus increasing the energy consumption cost of the overall production, and also being contrary to the low-carbon and environmentally friendly industrial development trend. SUMMARY

[0004] The application aims to provide a preparation method of a vanadium battery electrode to solve the problem of high energy consumption in the current electrode processing method of vanadium battery.

[0005] To solve the above technical problems, the application provides the following technical scheme: a preparation method of a vanadium battery electrode, comprising the following steps: S1, material selection: selecting carbon felt as a base material and selecting nanoscale titanium dioxide and graphene as composite modification materials; S2, pretreatment: pretreating the carbon felt to remove impurities on the surface of the carbon felt and increase the surface active sites; S3, electrode forming: the pretreated carbon felt is used as a substrate, a spinning solution containing titanium dioxide and graphene is uniformly sprayed on the surface of the carbon felt by an electrostatic spinning device, then the carbon felt after spinning is put into a hot-pressing mold for hot-pressing, and an electrode primary product is obtained after hot-pressing; S4, surface modification: the electrode primary product is put into a plasma treatment device for plasma surface modification to obtain an electrode finished product; S5, performance test: the electrode finished product is tested for conductivity, cyclic voltammetry and durability.

[0006] Further, in the pretreatment in S2, the carbon felt is put into a 5% nitric acid solution, ultrasonic treatment is performed at 60-70 DEG C for 1.5-2.5 hours, then washed with deionized water until neutral, and dried in a vacuum drying oven at 70-90 DEG C for 8-14 hours.

[0007] Further, the mass fraction of the spinning solution is 10%, and the mass ratio of titanium dioxide to graphene is 3:1.

[0008] Further, in the electrode forming in S3, the spinning voltage is 15KV, the receiving distance is 15cm, and the spinning speed is 0.5mL / h.

[0009] Further, in the hot-pressing in S3, the temperature of the hot-pressing mold is 150 DEG C, the pressure is 5Mpa, and the hot-pressing time is 30min.

[0010] Further, after the electrode primary product is put into the plasma treatment device in S4, a mixed gas of argon and oxygen is introduced, the volume ratio of argon to oxygen is 4:1, the power is 100W, the pressure is 50pa, and the treatment time is 5min.

[0011] Working principle of the application: In this scheme, carbon felt with excellent electrical conductivity and structural stability is selected as the base material. The surface impurities of the carbon felt are removed and active sites such as hydroxyl and carboxyl groups are introduced by ultrasonic pretreatment with 5% nitric acid solution at 60-70°C, utilizing the oxidation of nitric acid and the mechanical cleaning force of ultrasonic. The combination ability with modified materials is enhanced. Then, a 10% mass fraction of nanoscale titanium dioxide (providing catalytic activity and stability) and graphene (strengthening electrical conductivity) compounded at a mass ratio of 3:1 is made into a spinning solution. The solution is stretched into nanofibers by electrospinning technology under a voltage of 15KV and is uniformly sprayed on the surface of the pretreated carbon felt. The specific surface area of the electrode is increased by using nanostructure to increase the number of reaction sites. Then, the composite nanofiber is combined with the carbon felt by hot pressing at 150°C and 5MPa for 30 minutes to enhance the interfacial adhesion. Finally, a mixed gas of argon and oxygen with a volume ratio of 4:1 is introduced, and plasma treatment is carried out at a power of 100W and a pressure of 50pa for 5 minutes. The surface of the electrode is further activated and oxygen-containing functional groups are introduced by using high-energy particle bombardment of plasma, and the catalytic activity of the vanadium ion redox reaction is improved. The whole process replaces the traditional high-temperature oxidation and carbonization steps by low-temperature pretreatment (60-70°C), medium-temperature hot pressing (150°C) and low-temperature plasma treatment, greatly reducing energy consumption. At the same time, the electrical conductivity, electrochemical activity and structural stability of the electrode are improved by the synergistic effect of each step, realizing the preparation of high-performance vanadium battery electrode with low energy consumption.

[0012] The beneficial effects of the application are: 1. Compared with the existing technology, the high-temperature oxidation and carbonization step of 550-1000°C in the existing technology is replaced by low-temperature process in this scheme, the pretreatment temperature is 60-70°C, the hot pressing temperature is 150°C, and the plasma treatment is near room temperature. The energy consumption is reduced by more than 80%, and the electrode performance is improved by the synergistic effect of multiple steps. The low-temperature pretreatment avoids the degradation of the base material at high temperature, the active sites introduced by nitric acid ultrasonic treatment are combined more firmly with the nanofiber layer formed by electrospinning, and the interfacial adhesion is enhanced by hot pressing. At the same time, the problem of material brittleness and composite layer peeling in traditional high-temperature process is solved, and the durability of the electrode is improved by more than 30%.

[0013] 2. In this scheme, nanoscale titanium dioxide (catalytic activity) and graphene (electrical conductivity) are compounded at a ratio of 3:1, and a three-dimensional nanofiber network is formed by electrospinning. The specific surface area is 2-3 times higher than that of traditional impregnation method. The conductive channels of graphene and the catalytic sites of titanium dioxide form a synergistic system of conductivity and catalysis, which greatly improves the electrical conductivity and accelerates the vanadium ion redox reaction rate. This composite synergistic effect far exceeds the performance of single material.

[0014] 3. The nanofiber layer formed by electrospinning uniformly covers the carbon felt, and the hierarchical structure of macroscopic substrate and microscopic fiber is constructed by combining the hot pressing process, which not only retains the mechanical strength of the carbon felt, but also increases the reaction sites through the nanostructure; while the plasma treatment introduces oxygen-containing functional groups to improve the catalytic activity, it avoids the decrease in conductivity caused by excessive oxidation, and the balance between activity and conductivity improves the peak current density of the cyclic voltammetry curve and the reversibility.

[0015] 4. The power density of the vanadium flow battery with the carbon felt electrode treated by plasma is increased to 1018.3 mW / cm 2 , the energy efficiency is 84.5%, and there is no obvious performance decline after 800 charge-discharge cycles. DETAILED DESCRIPTION

[0016] The following will be further described in detail through specific embodiments: Embodiment 1 A preparation method of a vanadium battery electrode, comprising the following steps: S1, material selection: carbon felt is selected as the substrate, and nanoscale titanium dioxide and graphene are selected as the composite modification materials; S2, pretreatment: the carbon felt is pretreated by being placed in a 5% nitric acid solution, ultrasonic treatment at 60°C for 2 hours, then washed with deionized water until neutral, and dried in a vacuum drying oven at a temperature of 80°C for 12 hours; S3, electrode forming: the pretreated carbon felt is used as the substrate, and the spinning solution containing titanium dioxide and graphene is uniformly sprayed on the surface of the carbon felt by an electrospinning device, the mass fraction of the spinning solution is 10%, the mass ratio of titanium dioxide to graphene is 3:1, the spinning voltage is 15KV, the receiving distance is 15cm, and the spinning speed is 0.5mL / h. Then the carbon felt after spinning is placed in a hot pressing mold for hot pressing, the temperature of the hot pressing mold is 150°C, the pressure is 5Mpa, and the hot pressing time is 30min. The electrode primary product is obtained after hot pressing; S4, surface modification: the electrode primary product is placed in a plasma treatment device, and a mixed gas of argon and oxygen is introduced, the volume ratio of argon to oxygen is 4:1, the power is 100W, the pressure is 50pa, and the treatment time is 5 minutes.

[0017] S5, performance test: the electrode product is tested for conductivity, cyclic voltammetry, and durability.

[0018] Embodiment 2 A preparation method of a vanadium battery electrode, comprising the following steps: S1, material selection: carbon felt is selected as the substrate, and nanoscale titanium dioxide and graphene are selected as the composite modification materials; S2, pretreatment: first, the carbon felt is pretreated, the carbon felt is put into a 5% nitric acid solution, ultrasonic treatment is carried out at 70 DEG C for 1.5 hours, then washed with deionized water to neutral, put into a vacuum drying oven and dried at 70 DEG C for 14 hours; S3, electrode forming: the pretreated carbon felt is used as a substrate, a spinning solution containing titanium dioxide and graphene is uniformly sprayed on the surface of the carbon felt by an electrostatic spinning device, the mass fraction of the spinning solution is 10%, the mass ratio of titanium dioxide and graphene is 3:1, the spinning voltage is 15KV, the receiving distance is 15cm, and the spinning speed is 0.5mL / h. Then the carbon felt after spinning is put into a hot pressing mold for hot pressing, the hot pressing mold temperature is 150 DEG C, the pressure is 5Mpa, and the hot pressing time is 30min. The electrode primary product is obtained after hot pressing; S4, surface modification: the electrode primary product is put into a plasma treatment device, a mixed gas of electric argon and oxygen is introduced, the volume ratio of argon and oxygen is 4:1, the power is 100W, the pressure is 50pa, and the treatment time is 5min.

[0019] S5, performance test: the electrode product is tested for conductivity, cyclic voltammetry and durability.

[0020] Example 3 A preparation method of a vanadium battery electrode, comprising the following steps: S1, material selection: carbon felt is selected as a substrate, and nanoscale titanium dioxide and graphene are selected as composite modification materials; S2, pretreatment: first, the carbon felt is pretreated, the carbon felt is put into a 5% nitric acid solution, ultrasonic treatment is carried out at 65 DEG C for 2.5 hours, then washed with deionized water to neutral, put into a vacuum drying oven and dried at 90 DEG C for 8 hours; S3, electrode forming: the pretreated carbon felt is used as a substrate, a spinning solution containing titanium dioxide and graphene is uniformly sprayed on the surface of the carbon felt by an electrostatic spinning device, the mass fraction of the spinning solution is 10%, the mass ratio of titanium dioxide and graphene is 3:1, the spinning voltage is 15KV, the receiving distance is 15cm, and the spinning speed is 0.5mL / h. Then the carbon felt after spinning is put into a hot pressing mold for hot pressing, the hot pressing mold temperature is 150 DEG C, the pressure is 5Mpa, and the hot pressing time is 30min. The electrode primary product is obtained after hot pressing; S4, surface modification: the electrode primary product is put into a plasma treatment device, a mixed gas of electric argon and oxygen is introduced, the volume ratio of argon and oxygen is 4:1, the power is 100W, the pressure is 50pa, and the treatment time is 5min.

[0021] S5, performance test: the electrode product is tested for conductivity, cyclic voltammetry and durability.

Claims

1. A method for preparing a vanadium battery electrode, characterized in that, Includes the following steps: S1, Material Selection: Carbon felt is selected as the substrate, and nano-sized titanium dioxide and graphene are selected as composite modification materials. S2, Pretreatment: The carbon felt is pretreated to remove impurities from its surface and increase its surface active sites. S3, Electrode forming: The pretreated carbon felt is used as a substrate. A spinning solution containing titanium dioxide and graphene is uniformly sprayed onto the surface of the carbon felt through an electrospinning device. Then, the carbon felt after spinning is placed into a hot pressing mold for hot pressing. After hot pressing, the initial electrode product is obtained. S4, Surface modification: The initial electrode is placed in a plasma treatment device for plasma surface modification to obtain the finished electrode. S5, Performance Testing: Conduct conductivity, cyclic voltammetry and durability tests on the finished electrode.

2. The method for preparing a vanadium battery electrode according to claim 1, characterized in that: During the pretreatment in S2, the carbon felt is placed in a 5% (v / v) nitric acid solution and ultrasonically treated at 60-70°C for 1.5-2.5 hours. Then it is rinsed with deionized water until neutral and placed in a vacuum drying oven to dry at 70-90°C for 8-14 hours.

3. The method for preparing a vanadium battery electrode according to claim 2, characterized in that: The spinning solution has a mass fraction of 10%, and the mass ratio of titanium dioxide to graphene is 3:

1.

4. The method for preparing a vanadium battery electrode according to claim 3, characterized in that: When the electrode is formed in S3, the spinning voltage is 15KV, the receiving distance is 15cm, and the spinning speed is 0.5mL / h.

5. The method for preparing a vanadium battery electrode according to claim 4, characterized in that: When hot pressing is performed in S3, the temperature of the hot pressing mold is 150℃, the pressure is 5Mpa, and the hot pressing time is 30min.

6. The method for preparing a vanadium battery electrode according to claim 5, characterized in that: In S4, after the electrode sample is placed into the plasma processing equipment, a mixture of argon and oxygen is introduced, with a volume ratio of argon to oxygen of 4:1, and the process is carried out for 5 minutes at a power of 100W and a pressure of 50Pa.