A hydrophilic liquid flow battery electrode fabric and preparation method thereof

Abstract

The present invention discloses a hydrophilic liquid flow battery electrode fabric and a preparation method. The present invention makes the pre-oxidized silk fabric, after carbonization and activation, be impregnated with a hydrophilic conductive slurry so that the hydrophilic conductive slurry is fully attached to the surface of the fabric fiber, and then cured at high temperature so that the slurry and the fabric fiber are tightly combined to make a highly hydrophilic electrode conductive fabric. The hydrophilic conductive slurry includes the following components in weight percentage: 10%-30% hydrophilic carbon conductive powder; 5-30% acid and alkali resistant resin; 0.5%-10% dispersant; 0.2-5% defoamer; 0.2-5% thickener; 0.2-5% leveling agent; 0.2-5% film-forming agent; 20%-50% solvent. The hydrophilic coating formed by curing the hydrophilic conductive slurry on the surface of the fabric fiber of the present application has a strong adhesion, and the hydrophilicity of the coating is not easy to deactivate.

Description

Technical Field

[0001] The invention relates to the field of new energy technology, and in particular to a hydrophilic liquid flow battery electrode fabric and a preparation method thereof. Background Art

[0002] The electrode fabrics currently used in liquid flow batteries on the market are mainly hydrophilic graphite felt and hydrophilic electrodes. The main preparation process is: select pre-oxidized silk fibers with good uniformity and consistency, cut them into short fibers, and then needle-punch them into pre-oxidized silk needle-punched felt or spin-twist them into cloth. The pre-oxidized silk needle-punched felt or pre-oxidized silk cloth is first carbonized and then graphitized to make graphite felt. After that, it is activated by one or more mixed gases such as olefin gases, ammonia or water vapor in a high temperature environment, and hydrophilic functional groups are grafted on the surface of the graphitized carbon fibers to make hydrophilic graphite felt.

[0003] The existing technology has the following problems: (1) In the current activation process of grafted active functional groups, the hydrophilic functional groups grafted on the surface of carbon fibers are easy to fall off and have relatively poor bonding strength; (2) The hydrophilic functional groups are easy to react with other substances in the air or substances on the packaging materials and lose their hydrophilicity; (3) High temperature, sunlight and salt spray environment can cause the hydrophilic functional groups to fall off or react, leading to deactivation; (4) During activation, the requirements for activation equipment are high and the equipment cost is high; the activation process is a high-energy, high-pollution and high-emission process, and the environmental protection treatment cost is high. At the same time, the activation process also has fire and anti-virus safety risks, and the fire and anti-virus treatment costs are also high. Therefore, the comprehensive production cost of the activation process is high, the production efficiency is low, and the production cycle is long. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a hydrophilic liquid flow battery electrode fabric and a preparation method thereof.

[0005] In a first aspect, the present invention provides a hydrophilic conductive slurry, which is realized by adopting the following technical solution.

[0006] A hydrophilic conductive paste comprises the following components in percentage by weight:

[0007]

[0008]

[0009] Furthermore, the hydrophilic carbon conductive powder is a mixed powder of one or more of graphite powder, carbon nanotube powder, graphene powder, conductive carbon black powder and carbon fiber powder.

[0010] Furthermore, the preparation method of the hydrophilic carbon conductive powder is: the powder is isolated from air at 800-1200°C, CO2 or water vapor or a mixture of the two is introduced, and the treatment is carried out for 3-20 minutes to graft the surface of the powder.

[0011] Furthermore, the acid and alkali resistant resin is selected from organic fluorine resin or polypropylene resin.

[0012] Furthermore, the dispersant is selected from polyquaternary ammonium salt surfactants or non-ionic polymer surfactants.

[0013] Furthermore, the defoaming agent is an alcohol or modified silicone defoaming agent.

[0014] Furthermore, the thickener is a non-ionic high molecular polymer.

[0015] Furthermore, the leveling agent is a polyether-modified organic silicon polymer.

[0016] Furthermore, the film-forming agent is an alcohol substance.

[0017] In a second aspect, the present invention provides a method for preparing a hydrophilic conductive slurry, which is achieved by adopting the following technical solution.

[0018] A method for preparing the above hydrophilic conductive slurry comprises the following steps:

[0019] a. Add a specified amount of hydrophilic carbon conductive powder into a solvent, add a dispersant, and prepare a dispersion after pre-dispersion and sand grinding;

[0020] b. adding the obtained dispersion to a prescribed amount of acid and alkali resistant resin;

[0021] c. Add a specified amount of defoamer, thickener, leveling agent and film-forming agent to the mixture obtained in step b, stir thoroughly, and then repeatedly squeeze to obtain a hydrophilic conductive slurry.

[0022] In a third aspect, the present invention provides a method for preparing a liquid flow battery electrode fabric, which is achieved by adopting the following technical solution.

[0023] A method for preparing a flow battery electrode fabric comprises the following steps:

[0024] Ⅰ. Preparation of fabric:

[0025] S1. Select pre-oxidized silk fibers with a limiting oxygen index of 40-45%, cut them into short fibers, and then needle-punch them into pre-oxidized silk needle-punched felt or spin, twist, and weave them into pre-oxidized silk cloth;

[0026] S2. The pre-oxidized needle felt or pre-oxidized silk cloth is carbonized to form a carbon fiber fabric;

[0027] S3. The carbonized carbon fiber fabric is graphitized to form a graphitized carbon fiber fabric;

[0028] Ⅱ. Prepare hydrophilic conductive slurry

[0029] The hydrophilic conductive slurry is prepared by the above method;

[0030] III. Padding treatment

[0031] The graphitized carbon fiber fabric obtained in step I is subjected to a padding treatment using the hydrophilic conductive slurry obtained in step II;

[0032] Ⅳ. Drying and curing;

[0033] Ⅴ. Cutting.

[0034] Furthermore, in step ⅠS2, the carbonization treatment conditions are: the carbonization temperature is 800-1500°C, the protective atmosphere is argon or nitrogen, and the treatment time is 2-6h.

[0035] Furthermore, in step ⅠS3, the graphitization temperature is 1800-2500°C, and the maximum temperature holding time is 10-600 minutes.

[0036] Furthermore, in step IV, the drying and curing treatment conditions are: drying time 10-30 minutes, and drying temperature 100-200°C.

[0037] In a fourth aspect, the present invention provides a liquid flow battery electrode fabric, which is realized by adopting the following technical solution.

[0038] A liquid flow battery electrode fabric prepared by the above preparation method.

[0039] This application has the following beneficial effects.

[0040] (1) The hydrophilic coating formed by curing the hydrophilic conductive slurry on the surface of the fabric fiber has strong adhesion, and the hydrophilicity of the coating is not easy to deactivate; the coating does not react with other substances in the air or substances on the packaging material; the coating has high resistance to heat, sunlight and salt spray;

[0041] (2) When impregnating the hydrophilic slurry, the equipment requirements are relatively low, and ordinary textile impregnation equipment can meet the requirements; the impregnation and curing slurry process has low energy consumption, no pollution and very little emission, and the environmental protection treatment cost is low; the impregnation and curing hydrophilic slurry process has no fire and anti-toxic safety risks, and no fire and anti-toxic treatment is required; the hydrophilic treatment process has low comprehensive production cost, high production efficiency and short production cycle. DETAILED DESCRIPTION

[0042] The present invention will be further described below in conjunction with the embodiments.

[0043] Example 1

[0044] A method for preparing a flow battery electrode fabric comprises the following steps:

[0045] (1) Fabric preparation: Select preoxidized silk fibers with a limiting oxygen index of 43%, cut them into 7 cm short fibers, and then needle-punch them into 5 mm thick preoxidized silk needle-punched fabrics with a width of 1.8 m. The preoxidized silk needle-punched fabrics are first carbonized in a continuous carbonization furnace. Nitrogen is introduced into the furnace to maintain a slightly positive pressure to provide atmosphere protection for the entire carbonization process. The carbonization temperature is 1200°C, the speed of the preoxidized silk fabric in the continuous carbonization furnace is 0.5 m / min, and the furnace chamber length is 50 m to make a carbon fiber fabric. The carbonized carbon fiber fabric is rolled into a 100 m long roll and then placed in an intermittent graphitization furnace for graphitization. The graphitization temperature is 2200°C, and the temperature is raised from room temperature to 2200°C at a rate of 5°C / min. When it reaches 2200°C, it is maintained at 2200°C for 300 min, then the power is cut off and the temperature is naturally cooled to make a graphitized fabric;

[0046] (2) Preparation of hydrophilic carbon conductive powder: Weigh 100 kg of superconducting carbon black and 100 kg of carbon nanotube powder, mix them evenly and place them in a flat container made of carbon-carbon composite material, the height of the flat container is ≤ 2 cm, and the container containing the mixed carbon powder passes through a continuous carbonization furnace. Before the container passes through the carbonization furnace, the temperature is raised to 900°C and CO2 gas is passed through for more than 30 minutes to maintain a slight positive pressure. The air in the furnace is exhausted, and the time for the container to pass through the furnace is adjusted to ensure that the mixed carbon powder is kept warm in the furnace for 30 minutes and cooled for 20 minutes. Then the powder is taken out to prepare hydrophilic carbon conductive powder;

[0047] (3) Prepare acid-base resistant hydrophilic conductive slurry: weigh 60kg of deionized water, add 2kg of long-chain fatty alcohol polyoxyethylene ether (AEO-3) dispersant, and stir to make it completely dissolved in water, then add 20kg of carbon conductive powder prepared in step (2) and mix evenly to make a mixture, first disperse the mixture through a horizontal sand mill at 1000r / min for 6h to make a dispersion. Then add 13kg of water-based chlorinated polypropylene resin E-480T from Toyobo, Japan to the dispersion; then add 1kg of Guangdong Zhonglian Fine Chemical Defoamer B-0518, 1kg of thickener PEO-8, 1kg of water-based leveling agent BYK-333 and 2kg of film-forming agent propylene glycol. Use a vacuum planetary mixer to fully stir and make an acid-base resistant conductive coating with a viscosity of 600cps.

[0048] (4) Padding treatment: fix the graphitized electrode felt on a setting machine, pour the acid-base resistant hydrophilic conductive slurry prepared in step (3) into the padding tank of the setting machine, adjust the pressure to 3 MPa, and perform padding treatment on the graphite fabric;

[0049] (5) Drying and curing: After impregnation, the graphite fabric passes through a drying tunnel and is dried in the drying tunnel at a speed of 1 m / min, an effective tunnel length of 20 m, and a drying temperature of 120 °C;

[0050] (6) Cutting: Cut and shape as needed.

[0051] Performance Testing

[0052] 1. Hydrophilic test: Use a pipette to suck in 3 ml of deionized water, select five positions on the hydrophilic electrode fabric, and use a water contact angle tester to perform a contact angle test. The results show that the water droplets quickly penetrate into the fabric and the contact angle is 0;

[0053] 2. Square resistance test: Use a four-probe square resistance tester to test the square resistance value, the square resistance is ≤0.2Ω;

[0054] 3. Durability test: Cut 50mm*70mm hydrophilic electrode fabrics and fix them in PP pipes. Divide them into three groups and use 98% concentrated sulfuric acid, 37% concentrated hydrochloric acid and 50% concentrated sodium hydroxide respectively. In a PP pipe with a diameter of 100mm, the flow rate is 15L / min and the temperature is 40℃. The electrode fabrics are continuously flushed for 1500 hours. Then the electrode fabrics are dried at 80℃. The water contact angle is still 0 and the square resistance is ≤0.2Ω after testing again.

[0055] 4. Salt spray resistance test: After 1500h salt spray test, the water contact angle of the hydrophilic electrode fabric is still 0, and the square resistance is ≤0.2Ω;

[0056] 5. Battery installation test: electrode size 60mm*85mm; use flow channel graphite bipolar plate; use Nafion212 ion membrane; in the charge and discharge voltage range: 1.00-1.55V; compression ratio: electrode felt 40%, electrode cloth 35%; electrode fabric single layer assembled battery; constant current charge and discharge after 1500 cycles of battery charge and discharge, current density 110-200mA / cm2; at a current density of 110mA / cm2, coulomb efficiency (CE) ≥99%, voltage efficiency (VE) ≥95%, energy efficiency (EE) ≥90%; after 1500 battery charge and discharge cycles, coulomb efficiency (CE) ≥95%, voltage efficiency (VE) ≥90%, energy efficiency (EE) ≥85%;

[0057] 6. Strength test: According to the national standard GB / T 3923.2-2013, the breaking strength of the electrode felt is ≥15N, and the breaking strength of the electrode cloth is ≥20N; according to the national standard GB / T 3917.1-1997, the tearing strength of the electrode felt is ≥5N, and the tearing strength of the cloth is ≥10N.

[0058] The embodiments of this specific implementation method are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A hydrophilic conductive slurry, characterized in that: The composition includes the following weight percentages: Hydrophilic carbon conductive powder 10%-30%; Acid and alkali resistant resin 5-30%; Dispersant 0.5%-10%; Defoaming agent 0.2-5%; Thickener 0.2-5%; Leveling agent 0.2-5%; Film former 0.2-5%; Solvent 20%-50%; The hydrophilic carbon conductive powder is a mixed powder of one or more of graphite powder, carbon nanotube powder, graphene powder, conductive carbon black powder and carbon fiber powder; The preparation method of the hydrophilic carbon conductive powder is as follows: the powder is isolated from air at 800-1200°C, CO2 or water vapor or a mixture of the two is introduced for 3-20 minutes to graft and modify the surface of the powder; The acid and alkali resistant resin is selected from organic fluorine resin or polypropylene resin.

2. A method for preparing the hydrophilic conductive paste according to claim 1, characterized in that: The following steps are involved: a. Add a specified amount of hydrophilic carbon conductive powder into a solvent, add a dispersant, and prepare a dispersion after pre-dispersion and sand grinding; b. adding the dispersion prepared in step a to a specified amount of acid- and alkali-resistant resin; c. Add a specified amount of defoamer, thickener, leveling agent and film-forming agent to the mixture obtained in step b, stir thoroughly, and then degas to obtain a hydrophilic conductive slurry.

3. A method for preparing a flow battery electrode fabric, characterized in that: The following steps are involved: Ⅰ. Preparation of fabric: S1. Select pre-oxidized silk fibers with a limiting oxygen index of 40-45%, cut them into staple fibers, and then needle-punch them into pre-oxidized silk needle-punched felt or spin, twist, and weave them into pre-oxidized silk cloth; S2. The pre-oxidized needle felt or pre-oxidized silk cloth is carbonized to form a carbon fiber fabric; S3. The carbonized carbon fiber fabric is graphitized to form a graphitized carbon fiber fabric; Ⅱ. Preparation of hydrophilic conductive slurry The hydrophilic conductive slurry is prepared by the method of claim 2; III. Padding treatment The graphitized carbon fiber fabric obtained in step I is subjected to a padding treatment using the hydrophilic conductive slurry obtained in step II; Ⅳ. Drying and curing; Ⅴ. Cutting.

4. The method for preparing a flow battery electrode fabric according to claim 3, characterized in that: In step ⅠS2, the carbonization treatment conditions are: carbonization temperature is 800-1500°C, protective atmosphere is argon or nitrogen, and treatment time is 2-6h.

5. The method for preparing a flow battery electrode fabric according to claim 3, characterized in that: In step ⅠS3, the graphitization temperature is 1800-2500°C, and the maximum temperature holding time is 10-600 minutes.

6. The method for preparing a flow battery electrode fabric according to claim 3, characterized in that: In step IV, the drying and curing treatment conditions are: drying time 10-30 minutes, and drying temperature 100-200°C.

7. A liquid flow battery electrode fabric prepared by the preparation method according to any one of claims 3 to 6.

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