Method for constructing hydrophilic and oleophobic diaphragm surface based on ultraviolet curing process

Abstract

The invention relates to the technical field of flow battery diaphragm materials, in particular to a method for constructing a hydrophilic and oleophobic diaphragm surface based on an ultraviolet curing process. The method comprises the following steps: firstly preparing a series of nano titanium particles with different particle sizes, then grafting a fluoroalkyl chain to the surfaces of the nano titanium particles, then carrying out electrostatic spinning on the nano titanium particles to prepare an electrospun PAN / TiO2 fibrofelt, then soaking the electrospun PAN / TiO2 fibrofelt with a surface covering coating, and finally curing to completely crosslink residual groups, thereby obtaining the hydrophilic and oleophobic diaphragm material for the flow battery. After being coated with a series of hydrophilic and oleophobic substances and functional groups on the surface, the prepared flow battery diaphragm material has good hydrophilicity and oleophobicity, the battery performance of a flow battery is improved, and a new thought is provided for development of flow battery diaphragms.

Description

Technical Field

[0001] This invention relates to the field of flow battery membrane material technology, specifically a method for constructing a hydrophilic and oleophobic membrane surface based on ultraviolet light curing process. Background Technology

[0002] Traditional fossil fuels such as coal, oil, and natural gas not only have limited reserves, but also cause serious environmental pollution during extraction and use, leading to increased greenhouse gas emissions and more frequent global climate anomalies. Faced with this crisis, promoting a revolution in energy consumption, supply, technology, and systems, and accelerating the development of a low-carbon economy has become a global consensus.

[0003] Flow batteries, as a novel energy storage technology, play a crucial role in the energy transition. Compared to lithium batteries, flow batteries offer significant advantages such as intrinsic safety, long cycle life, and easily scalable capacity. They utilize a working principle of separate circulation of positive and negative electrolytes, converting electrical energy into chemical energy through changes in the valence state of active elements. Using water as the electrolyte solvent fundamentally eliminates the risk of combustion and explosion. With the increasing proportion of installed capacity from new energy sources, the demand for long-term energy storage in the power grid is becoming increasingly urgent. Flow batteries can effectively address the randomness and volatility of renewable energy sources such as wind and solar power, storing excess energy during peak power generation and supplementing the grid when power supply is insufficient, ensuring the stable operation of the power system. In the future, with advancements in materials science and engineering technology, flow batteries are expected to become a core technology for building new power systems, providing crucial support for the global low-carbon energy transition.

[0004] As a core component of flow batteries, the separator's performance directly determines the battery's efficiency, stability, and lifespan. The separator primarily performs two functions in flow batteries: first, it physically isolates the positive and negative electrolytes, preventing short circuits and self-discharge caused by the mixing of active materials; second, it selectively conducts specific ions (such as protons) to form a complete current loop and maintain charge balance. This precise control of ion transport requires the separator to possess high ion selectivity and high proton conductivity. Furthermore, because flow batteries typically operate in environments characterized by strong acidity, strong oxidizing properties (e.g., pentavalent vanadium ions in vanadium redox flow batteries), and high current, the separator must also possess excellent chemical stability and mechanical strength to ensure stable long-term operation of the battery.

[0005] Among the many properties of membranes, hydrophilicity and oleophobicity (or superhydrophilicity) are crucial characteristics, profoundly affecting the ion conduction efficiency, selectivity, and durability of the membrane. Specifically: 1. Improved ion conduction efficiency: Hydrophilic membrane materials are more compatible with the aqueous electrolytes commonly used in flow batteries, facilitating the formation of continuous ion transport channels. For example, TiO2 nanotubes, due to their superhydrophilicity, can be uniformly dispersed in a Nafion matrix, significantly improving the proton conductivity of the composite membrane. 2. Enhanced ion selectivity: Hydrophilic membrane layers help achieve precise ion selectivity through an "ion sieving" mechanism. Hydrated ions (such as H+)... + Smaller ions easily pass through hydrophilic channels, while larger hydrated vanadium ions are effectively blocked. The "nanogate" constructed using water-swellable materials dynamically adjusts the channel size through its hydrophilic properties, achieving extremely high ion selectivity. III. Improved Stability and Durability: Hydrophilic materials generally have better compatibility with aqueous electrolytes, reducing membrane swelling and degradation. The high bond energy of the CF bonds in perfluorosulfonic acid membranes inherently provides excellent chemical stability, while the introduction of superhydrophilic nanomaterials further optimizes its internal structure, enhancing its resistance to aging under harsh environments, thereby significantly extending battery cycle life.

[0006] In summary, developing methods to construct hydrophilic and oleophobic membrane surfaces is one of the key research directions for promoting the large-scale commercial application of flow battery technology. Summary of the Invention

[0007] The purpose of this invention is to address the problems identified in existing technologies by providing a method for constructing a hydrophilic and oleophobic separator surface based on a UV curing process. In this method, a series of nano-titanium particles of different particle sizes are first prepared. Then, fluoroalkyl chains are grafted onto the surface of the nano-titanium particles. Next, electrospinning is performed to prepare electrospun PAN / TiO2 fiber felt. This felt is then soaked in a surface coating and finally cured to completely crosslink the remaining groups, thus obtaining the hydrophilic and oleophobic separator material for flow batteries. This invention solves the problems of poor hydrophilicity and oleophobicity in existing flow battery separators.

[0008] To achieve the above-mentioned objectives, the specific technical solution of the present invention is as follows: A method for constructing a hydrophilic and oleophobic membrane surface based on ultraviolet light curing process, the method comprising the following steps: (1) Add tetramethoxytitanium, anhydrous ethanol and deionized water to the container, stir in a water bath and keep warm for a period of time to obtain a series of nano-titanium particles with different particle sizes. (2) Dissolve the nano-titanium particles obtained in step (1) in an ethanol solution to prepare a nano-titanium / ethanol solution of a certain concentration. Then add perfluorooctyl sulfonyl aminopropyltrimethoxysilane to the nano-titanium / ethanol solution and react at a certain temperature for a period of time to graft the fluoroalkyl chain onto the surface of the nanoparticles to obtain modified nano-titanium particles. (3) Dissolve the modified nano-titanium particles obtained in step (2) in a certain concentration of PAN / DMF solvent and stir to prepare an electrospinning solution; (4) Prepare electrospun PAN / TiO2 fiber mat by applying the electrospun solution obtained in step (3) under certain conditions such as voltage, spinning distance, and feed rate; (5) The PAN / TiO2 fiber felt obtained in step (4) is placed in a 2.5 wt% dimethyl sulfoxide coating solution of sulfonated polybenzimidazole and reacted at a certain temperature for a period of time to obtain PAN / TiO2 / coating fiber felt. The dimethyl sulfoxide coating solution contains different masses of monofunctional UV oligomer (EM3101), waterborne polyurethane acrylate (611A-85), multifunctional oligomer (BASF PE55WN), oleophobic modified titanium sol, photoinitiator WB-4785, and sodium dodecylbenzenesulfonate; (6) The PAN / TiO2 / coating fiber felt obtained in step (5) is placed in a UV curing machine and irradiated for a period of time under certain wavelength and energy conditions to make the residual groups completely crosslinked, thus obtaining the hydrophilic and oleophobic membrane.

[0009] The final separator was removed, its hydrophilic and oleophobic properties were tested, and a flow battery was assembled to further test its battery performance.

[0010] Furthermore, in step (1) of the method for constructing a hydrophilic and oleophobic membrane surface based on ultraviolet light curing process, the mass ratio of tetramethoxytitanium, anhydrous ethanol and deionized water is 5~10, 1~5 and 1~5.

[0011] Furthermore, in step (1) of the method for constructing a hydrophilic and oleophobic membrane surface based on ultraviolet light curing process, the water bath stirring temperature is 30~80℃ and the heat preservation reaction time is 1~12h.

[0012] Furthermore, in step (1) of the method for constructing a hydrophilic and oleophobic membrane surface based on ultraviolet light curing process, a series of nano-titanium particles with a particle size of 100~800 nm are obtained.

[0013] Furthermore, in step (2) of the method for constructing a hydrophilic and oleophobic membrane surface based on ultraviolet light curing process, the concentration of the prepared nano-titanium / ethanol solution is 1~5 g / L; the mass ratio of perfluorooctylaminopropyltrimethoxysilane to tetramethoxytitanium is 1~10:5~10.

[0014] Furthermore, in step (2) of the method for constructing a hydrophilic and oleophobic membrane surface based on ultraviolet light curing process, the reaction temperature is 30~80℃ and the reaction time is 1~12h.

[0015] Furthermore, in step (3) of the method for constructing a hydrophilic and oleophobic membrane surface based on ultraviolet light curing process, the concentration of the prepared PAN / DMF solvent is 5~20 g / L.

[0016] Furthermore, in step (4) of the method for constructing a hydrophilic and oleophobic membrane surface based on ultraviolet curing process, the voltage is 12~20 kV, the spinning distance is 5~20 cm, and the feeding speed is 0.001~0.1 mm / min.

[0017] Furthermore, in step (5) of the method for constructing a hydrophilic and oleophobic membrane surface based on ultraviolet light curing process, the reaction temperature is 30~80℃ and the reaction time is 1~12h.

[0018] Furthermore, in step (5) of the method for constructing a hydrophilic and oleophobic membrane surface based on ultraviolet light curing process, the added components are monofunctional UV oligomer (EM3101), waterborne polyurethane acrylate (611A-85), multifunctional oligomer (BASF PE55WN), oleophobic modified titanium sol, photoinitiator WB-4785, and sodium dodecylbenzene sulfonate.

[0019] Furthermore, in step (6) of the method for preparing the modified separator for flow batteries, the curing wavelength is 205-405 nm, the curing energy is 200-300 mJ / cm², and the curing time is 1-12 h.

[0020] This invention also protects a flow battery in which a hydrophilic and oleophobic separator is constructed using an ultraviolet curing process obtained by the above-described method or combination of method steps.

[0021] Furthermore, the flow battery includes iron-chromium, vanadium-based, zinc-iron, ferric, zinc-bromine, sodium / bromine polysulfide, titanium-manganese, or organic system flow batteries.

[0022] The design concept of this invention is: This invention first prepares a series of nano-titanium particles with different particle sizes, then grafts fluoroalkyl chains onto the surface of the nano-titanium particles, and then electrospins them to prepare electrospun PAN / TiO2 fiber felt. Next, the felt is impregnated with a surface coating, and finally cured to completely crosslink the residual groups, thus obtaining the hydrophilic and oleophobic separator material for flow batteries. The melamine foam-based electrode prepared by this invention, after being coated with a series of hydrophilic and oleophobic substances and functional groups, exhibits good hydrophilicity and oleophobicity, improving the battery performance of flow batteries and providing a new approach for the development of flow battery electrodes.

[0023] Compared with the prior art, the positive effects of the present invention are reflected in: 1. Synergistic performance design: Through the composite process of "nanoparticle modification + electrospinning + UV curing coating", the organic combination of hydrophilicity and oleophobicity is achieved, providing conditions for obtaining high proton conductivity and low permeability of active substances.

[0024] 2. Precise and controllable structure: Electrospinning technology can precisely control the pore size and porosity of the membrane; UV curing process can achieve rapid and deep cross-linking reaction to form a stable three-dimensional network structure.

[0025] 3. Wide applicability: The membrane prepared by this method can be used in various flow batteries with different systems such as vanadium, zinc-bromine, and iron-chromium, showing broad application prospects.

[0026] 4. Potential cost-effectiveness: Compared to expensive Nafion films, the UV curing process used in this technology is highly efficient and energy-saving, which is conducive to large-scale production.

[0027] 5. The separator prepared by this invention significantly improves the performance of a single flow battery, providing a new approach for the development of flow battery separators. Attached Figure Description

[0028] Figure 1 This is a microscopic morphology diagram of the PAN / TiO2 / coating fiber felt prepared in Example 1 of the present invention. Detailed Implementation

[0029] All features disclosed in this specification, or all steps in all disclosed methods or processes, may be combined in any way, except for mutually exclusive features and / or steps.

[0030] Any feature disclosed in this specification (including the claims and abstract) may be replaced by other equivalent or similar features, unless specifically stated otherwise. That is, unless specifically stated otherwise, each feature is merely one example of a series of equivalent or similar features.

[0031] In the specific implementation process, a series of nano-titanium particles with different particle sizes are first prepared, then fluoroalkyl chains are grafted onto the surface of the nano-titanium particles, and then electrospinning is performed to prepare electrospun PAN / TiO2 fiber felt. Next, the surface is soaked and coated with a coating, and finally cured to completely crosslink the residual groups to obtain the hydrophilic and oleophobic separator material for the flow battery.

[0032] This invention relates to a method for preparing a hydrophilic and oleophobic membrane surface based on ultraviolet light curing technology, comprising the following steps: (1) Add 5~10g tetramethoxytitanium, 1~5g anhydrous ethanol and 1~5g deionized water to the flask, stir in a water bath at 30~80℃ and keep warm for 1~12h to obtain a series of nano-titanium particles with a particle size of 100~800 nm.

[0033] (2) Dissolve the nano-titanium particles obtained in step (2) in an ethanol solution to prepare a nano-titanium / ethanol solution with a concentration of 1~5 g / L. Then add 1~10 g of perfluorooctyl sulfonyl aminopropyltrimethoxysilane to it and react at 30~80℃ for 1~12 h to graft the fluoroalkyl chain onto the surface of the nanoparticles. (3) Dissolve 1~10 g of the modified nano-titanium particles obtained in step (2) in 5~20 g / L PAN / DMF solvent and stir to prepare an electrospinning solution; (4) Prepare electrospun PAN / TiO2 fiber mat by using the electrospun solution obtained in step (3) under conditions such as voltage of 12~20 kV, spinning distance of 5~20 cm, and feed rate of 0.001~0.1 mm / min; (5) The PAN / TiO2 fiber felt obtained in step (4) is placed in a 2.5 wt% dimethyl sulfoxide coating solution of sulfonated polybenzimidazole and reacted at 30~80℃ for 1~12h to obtain PAN / TiO2 / coating fiber felt. The dimethyl sulfoxide coating solution contains 0.1g~2g of monofunctional UV oligomer (EM3101), 0.1g~2g of waterborne polyurethane acrylate (611A-85), 0.1g~2g of polyfunctional oligomer (BASF PE55WN), 0.1g~2g of oleophobic modified titanium sol, 0.1g~2g of photoinitiator WB-4785, and 0.1g~2g of sodium dodecylbenzenesulfonate; (6) Place the PAN / TiO2 / coating fiber felt obtained in step (5) into a UV curing machine and irradiate it for 1~12h at a wavelength of 205-405 nm and an energy of 200-300 mJ / cm² to make the residual groups completely crosslinked, and obtain a hydrophilic and oleophobic membrane constructed based on the UV curing process. The final separator was removed, its hydrophilic and oleophobic properties were tested, and it was assembled into a flow battery for further testing of its battery performance.

[0034] The experimental materials used in this invention, such as tetramethoxytitanium, anhydrous ethanol, deionized water, UV oligomer (EM3101), waterborne polyurethane acrylate (611A-85), multifunctional oligomer (BASF PE55WN), oleophobic modified titanium sol, photoinitiator WB-4785, and sodium dodecylbenzenesulfonate, are all commercially available and do not require subsequent purification.

[0035] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0036] Unless otherwise specified, the process methods used in the embodiments are conventional methods; unless otherwise specified, the materials used are commercially available.

[0037] In this application, unless otherwise specified, % refers to mass percentage content, and all ratios refer to mass ratios; the liquid-to-solid ratio is the ratio of liquid volume (mL) to solid mass (g).

[0038] Example 1 In this embodiment, the preparation steps for constructing a hydrophilic and oleophobic membrane based on ultraviolet light curing process are as follows: (1) Add 5g tetramethoxytitanium, 5g anhydrous ethanol and 5g deionized water to the flask, stir in a water bath at 30°C and keep warm for 1h to obtain nano-titanium particles with a particle size of 100nm.

[0039] (2) Dissolve the nano-titanium particles obtained in step (1) in an ethanol solution to prepare a nano-titanium / ethanol solution with a concentration of 1 g / L. Then add 1 g of perfluorooctyl sulfonyl aminopropyltrimethoxysilane to it and react at 30°C for 1 h to graft the fluoroalkyl chain onto the surface of the nanoparticles and modify the nano-titanium particles. (3) Dissolve 1 g of the modified nano-titanium particles obtained in step (2) in 5 g / L PAN / DMF solvent, and stir to prepare an electrospinning solution; (4) The electrospinning solution obtained in step (3) was used to prepare electrospinning PAN / TiO2 fiber mat under the conditions of 12 kV voltage, 5 cm spinning distance and 0.001 mm / min feed rate. (5) The PAN / TiO2 fiber felt obtained in step (4) was placed in a 2.5 wt% dimethyl sulfoxide coating solution of sulfonated polybenzimidazole and reacted at 30°C for 1 hour to obtain PAN / TiO2 / coating fiber felt. The dimethyl sulfoxide coating solution contained 0.1 g of monofunctional UV oligomer (EM3101), 0.1 g of waterborne polyurethane acrylate (611A-85), 0.1 g of polyfunctional oligomer (BASF PE55WN), 0.1 g of oleophobic modified titanium sol, 0.1 g of photoinitiator WB-4785, and 0.1 g of sodium dodecylbenzenesulfonate; (6) The PAN / TiO2 / coating fiber felt obtained in step (5) is placed in a UV curing machine and irradiated for 1 hour at a wavelength of 205nm and an energy of 200 mJ / cm2 to completely crosslink the residual groups and obtain the diaphragm. (7) Remove the final separator, test its hydrophilic and oleophobic properties, and assemble the flow battery to further test its battery performance.

[0040] Testing showed that, after coating the flow battery membrane prepared in this embodiment with hydrophilic and oleophobic materials and functional groups, the hydrophilic contact angle of the membrane decreased to 23°, while the oleophobic contact angle increased to 154°. When this membrane was assembled into a vanadium redox flow battery, at a current density of 150 mA / cm², [the following results were obtained]. 2 Under constant current charge and discharge test conditions, the energy efficiency of the battery using this separator is 72.3%.

[0041] Example 2 In this embodiment, the preparation steps for constructing a hydrophilic and oleophobic membrane based on ultraviolet light curing process are as follows: (1) Add 7 g tetramethoxytitanium, 5 g anhydrous ethanol and 5 g deionized water to a flask, stir in a water bath at 40°C and keep warm for 6 h to obtain nano-titanium particles with a particle size of 400 nm.

[0042] (2) Dissolve the nano-titanium particles obtained in step (2) in an ethanol solution to prepare a nano-titanium / ethanol solution with a concentration of 3 g / L. Then add 6 g of perfluorooctyl sulfonyl aminopropyltrimethoxysilane to it and react at 50°C for 6 h to graft the fluoroalkyl chain onto the surface of the nanoparticles and modify the nano-titanium particles. (3) Dissolve 5 g of the modified nano-titanium particles obtained in step (2) in 10 g / L PAN / DMF solvent and stir to prepare an electrospinning solution; (4) The electrospinning solution obtained in step (3) was used to prepare electrospinning PAN / TiO2 fiber mat under the conditions of 15 kV voltage, 15 cm spinning distance and 0.001 mm / min feed rate. (5) The PAN / TiO2 fiber felt obtained in step (4) was placed in a 2.5 wt% dimethyl sulfoxide coating solution of sulfonated polybenzimidazole and reacted at 70°C for 10 h to obtain PAN / TiO2 / coating fiber felt. The dimethyl sulfoxide coating solution contained 0.5 g of monofunctional UV oligomer (EM3101), 0.5 g of waterborne polyurethane acrylate (611A-85), 0.5 g of polyfunctional oligomer (BASF PE55WN), 0.5 g of oleophobic modified titanium sol, 0.5 g of photoinitiator WB-4785, and 0.5 g of sodium dodecylbenzenesulfonate; (6) The PAN / TiO2 / coating fiber felt obtained in step (5) is placed in a UV curing machine and irradiated for 5 hours at a wavelength of 265 nm and an energy of 250 mJ / cm² to completely crosslink the residual groups and obtain a diaphragm. (7) Remove the final separator, test its hydrophilic and oleophobic properties, and assemble the flow battery to further test its battery performance.

[0043] Testing showed that, after coating the flow battery membrane prepared in this embodiment with hydrophilic and oleophobic materials and functional groups, the hydrophilic contact angle of the membrane decreased to 27°, while the oleophobic contact angle increased to 184°. When this membrane was assembled into a vanadium redox flow battery, at a current density of 100 mA / cm², [the following results were obtained]. 2 Under constant current charge and discharge test conditions, the energy efficiency of the battery using this separator is 78.9%.

[0044] Example 3 In this embodiment, the preparation steps for constructing a hydrophilic and oleophobic membrane based on ultraviolet light curing process are as follows: (1) Add 10g tetramethoxytitanium, 4g anhydrous ethanol and 4g deionized water to a flask, stir in a water bath at 80°C and keep warm for 12h to obtain nano-titanium particles with a particle size of 800 nm.

[0045] (2) Dissolve the nano-titanium particles obtained in step (2) in an ethanol solution to prepare a nano-titanium / ethanol solution with a concentration of 5 g / L. Then add 10 g of perfluorooctyl sulfonyl aminopropyltrimethoxysilane to it and react at 80°C for 12 h to graft the fluoroalkyl chain onto the surface of the nanoparticles and modify the nano-titanium particles. (3) Dissolve 10 g of the modified nano-titanium particles obtained in step (2) in 20 g / L PAN / DMF solvent and stir to prepare an electrospinning solution; (4) The electrospinning solution obtained in step (3) was used to prepare electrospinning PAN / TiO2 fiber mat under the conditions of 20 kV voltage, 20 cm spinning distance and 0.1 mm / min feed rate; (5) The PAN / TiO2 fiber felt obtained in step (4) is placed in a 2.5 wt% dimethyl sulfoxide coating solution of sulfonated polybenzimidazole and reacted at 80°C for 12 h to obtain PAN / TiO2. 2 / Coating fiber felt. The dimethyl sulfoxide coating solution contains 2g of monofunctional UV oligomer (EM3101), 2g of waterborne polyurethane acrylate (611A-85), 2g of multifunctional oligomer (BASF PE55WN), 2g of oleophobic modified titanium sol, 2g of photoinitiator WB-4785, and 2g of sodium dodecylbenzenesulfonate; (6) Place the PAN / TiO2 / coating fiber mat obtained in step (5) into a UV curing machine and cure it at a wavelength of 405 nm and a temperature of 300 mJ / cm. 2 Irradiation under energy conditions for 12 hours completely crosslinks the residual groups, resulting in a membrane; (7) Remove the final separator, test its hydrophilic and oleophobic properties, and assemble the flow battery to further test its battery performance.

[0046] Testing showed that, after coating the flow battery membrane prepared in this embodiment with hydrophilic and oleophobic materials and functional groups, the hydrophilic contact angle of the membrane decreased to 21°, while the oleophobic contact angle increased to 166°. When this membrane was assembled into a titanium-manganese flow battery, at a current density of 50 mA / cm², [the following results were obtained]. 2 Under constant current charge and discharge test conditions, the energy efficiency of the battery using this separator is 81.4%.

[0047] Example 4 In this embodiment, the method for preparing the hydrophilic and oleophobic separator for the flow battery is as follows: (1) Add 7g tetramethoxytitanium, 4g anhydrous ethanol and 4g deionized water to a flask, stir in a water bath at 80°C and keep warm for 6h to obtain a series of nano-titanium particles with a diameter of 400 nm.

[0048] (2) Dissolve the nano-titanium particles obtained in step (2) in an ethanol solution to prepare a nano-titanium / ethanol solution with a concentration of 5 g / L. Then add 5 g of perfluorooctyl sulfonyl aminopropyltrimethoxysilane to it and react at 30°C for 12 h to graft the fluoroalkyl chain onto the surface of the nanoparticles and modify the nano-titanium particles. (3) Dissolve 1 g of the modified nano-titanium particles obtained in step (2) in 20 g / L PAN / DMF solvent and stir to prepare an electrospinning solution; (4) The electrospinning solution obtained in step (3) is used to prepare electrospinning PAN / TiO2 fiber mat under the conditions of 20 kV voltage, 20 cm spinning distance and 0.001 mm / min feed rate. (5) The PAN / TiO2 fiber felt obtained in step (4) was placed in a 2.5 wt% dimethyl sulfoxide coating solution of sulfonated polybenzimidazole and reacted at 30°C for 12 h to obtain PAN / TiO2 / coating fiber felt. The dimethyl sulfoxide coating solution contained 1 g of monofunctional UV oligomer (EM3101), 1 g of waterborne polyurethane acrylate (611A-85), 1 g of polyfunctional oligomer (BASF PE55WN), 1 g of oleophobic modified titanium sol, 1 g of photoinitiator WB-4785, and 1 g of sodium dodecylbenzenesulfonate. (6) Place the PAN / TiO2 / coating fiber mat obtained in step (5) into a UV curing machine and cure it at a wavelength of 205 nm and a temperature of 300 mJ / cm. 2 Irradiation under energy conditions for 12 hours completely crosslinks the residual groups, resulting in a membrane; (7) Remove the final separator, test its hydrophilic and oleophobic properties, and assemble the flow battery to further test its battery performance.

[0049] Testing showed that, after coating the flow battery membrane prepared in this embodiment with hydrophilic and oleophobic materials and functional groups, the hydrophilic contact angle of the membrane decreased to 14°, while the oleophobic contact angle increased to 198°. When this membrane was assembled into a zinc-iron flow battery, at a current density of 150 mA / cm², [the following results were obtained]. 2 Under constant current charge and discharge test conditions, the energy efficiency of the battery using this separator is 78.9%.

[0050] Example 5 In this embodiment, the method for preparing the hydrophilic and oleophobic separator for the flow battery is as follows: (1) Add 10g tetramethoxytitanium, 5g anhydrous ethanol and 5g deionized water to a flask, stir in a water bath at 80℃ and keep warm for 6h to obtain a series of nano-titanium particles with a particle size of 700 nm.

[0051] (2) Dissolve the nano-titanium particles obtained in step (2) in an ethanol solution to prepare a nano-titanium / ethanol solution with a concentration of 5 g / L. Then add 5 g of perfluorooctyl sulfonyl aminopropyltrimethoxysilane to it and react at 40°C for 6 h to graft the fluoroalkyl chain onto the surface of the nanoparticles and modify the nano-titanium particles. (3) Dissolve 7 g of the modified nano-titanium particles obtained in step (2) in 5 g / L PAN / DMF solvent and stir to prepare an electrospinning solution; (4) The electrospinning solution obtained in step (3) is used to prepare electrospinning PAN / TiO2 fiber mat under the conditions of 20 kV voltage, 10 cm spinning distance and 0.01 mm / min feed rate. (5) The PAN / TiO2 fiber felt obtained in step (4) was placed in a 2.5 wt% dimethyl sulfoxide coating solution of sulfonated polybenzimidazole and reacted at 40°C for 12 h to obtain PAN / TiO2 / coating fiber felt. The dimethyl sulfoxide coating solution contained 0.1 g of monofunctional UV oligomer (EM3101), 0.2 g of waterborne polyurethane acrylate (611A-85), 0.4 g of polyfunctional oligomer (BASF PE55WN), 0.4 g of oleophobic modified titanium sol, 0.7 g of photoinitiator WB-4785, and 0.7 g of sodium dodecylbenzenesulfonate; (6) Place the PAN / TiO2 / coating fiber mat obtained in step (5) into a UV curing machine and cure it at a wavelength of 305 nm and a curing temperature of 250 mJ / cm. 2 Irradiation under energy conditions for 6 hours completely crosslinks the residual groups, resulting in a membrane; (7) Remove the final separator, test its hydrophilic and oleophobic properties, and assemble the flow battery to further test its battery performance.

[0052] Testing showed that, after coating the flow battery membrane prepared in this embodiment with hydrophilic and oleophobic materials and functional groups, the hydrophilic contact angle of the membrane decreased to 34°, while the oleophobic contact angle increased to 131°. When this membrane was assembled into a zinc-bromine flow battery, at a current density of 80 mA / cm², [the following results were obtained]. 2 Under constant current charge and discharge test conditions, the energy efficiency of the battery using this separator is 69.1%.

[0053] Example 6 In this embodiment, the method for preparing the hydrophilic and oleophobic separator for the flow battery is as follows: (1) Add 7g tetramethoxytitanium, 4g anhydrous ethanol and 4g deionized water to a flask, stir in a water bath at 80°C and keep warm for 6h to obtain a series of nano-titanium particles with a diameter of 400 nm.

[0054] (2) Dissolve the nano-titanium particles obtained in step (2) in an ethanol solution to prepare a nano-titanium / ethanol solution with a concentration of 5 g / L. Then add 5 g of perfluorooctyl sulfonyl aminopropyltrimethoxysilane to it and react at 30°C for 12 h to graft the fluoroalkyl chain onto the surface of the nanoparticles and modify the nano-titanium particles. (3) Dissolve 1 g of the modified nano-titanium particles obtained in step (2) in 20 g / L PAN / DMF solvent and stir to prepare an electrospinning solution; (4) The electrospinning solution obtained in step (3) is used to prepare electrospinning PAN / TiO2 fiber mat under the conditions of 20 kV voltage, 20 cm spinning distance and 0.001 mm / min feed rate. (5) The PAN / TiO2 fiber felt obtained in step (4) was placed in a 2.5 wt% dimethyl sulfoxide coating solution of sulfonated polybenzimidazole and reacted at 30°C for 12 h to obtain PAN / TiO2 / coating fiber felt. The dimethyl sulfoxide coating solution contained 1.5 g of monofunctional UV oligomer (EM3101), 1.5 g of waterborne polyurethane acrylate (611A-85), 1.5 g of polyfunctional oligomer (BASF PE55WN), 1.5 g of oleophobic modified titanium sol, 1.5 g of photoinitiator WB-4785, and 1.5 g of sodium dodecylbenzenesulfonate. (6) Place the PAN / TiO2 / coating fiber mat obtained in step (5) into a UV curing machine and cure it at a wavelength of 255 nm and a curing temperature of 300 mJ / cm. 2 Irradiation under energy conditions for 6 hours completely crosslinks the residual groups, resulting in a membrane; (7) Remove the final separator, test its hydrophilic and oleophobic properties, and assemble the flow battery to further test its battery performance.

[0055] Testing showed that, after coating the flow battery membrane prepared in this embodiment with hydrophilic and oleophobic materials and functional groups, the hydrophilic contact angle of the membrane decreased to 21°, while the oleophobic contact angle increased to 187°. When this membrane was assembled into an all-iron flow battery, at a current density of 150 mA / cm², [the following results were obtained]. 2 Under constant current charge and discharge test conditions, the energy efficiency of the battery using this separator is 72.4%.

[0056] Example 7 In this embodiment, the method for preparing the hydrophilic and oleophobic separator for the flow battery is as follows: (1) Add 10g tetramethoxytitanium, 5g anhydrous ethanol and 5g deionized water to a flask, stir in a water bath at 50°C and keep warm for 10 h to obtain a series of nano-titanium particles with a diameter of 700 nm.

[0057] (2) Dissolve the nano-titanium particles obtained in step (2) in an ethanol solution to prepare a nano-titanium / ethanol solution with a concentration of 5 g / L. Then add 5 g of perfluorooctyl sulfonyl aminopropyltrimethoxysilane to it and react at 30°C for 12 h to graft the fluoroalkyl chain onto the surface of the nanoparticles and modify the nano-titanium particles. (3) Dissolve 7 g of the modified nano-titanium particles obtained in step (2) in 20 g / L PAN / DMF solvent and stir to prepare an electrospinning solution; (4) The electrospinning solution obtained in step (3) is used to prepare electrospinning PAN / TiO2 fiber mat under the conditions of 15 kV voltage, 15 cm spinning distance and 0.001 mm / min feed rate. (5) The PAN / TiO2 fiber felt obtained in step (4) was placed in a 2.5 wt% dimethyl sulfoxide coating solution of sulfonated polybenzimidazole and reacted at 80°C for 12 h to obtain PAN / TiO2 / coating fiber felt. The dimethyl sulfoxide coating solution contained 0.1 g of monofunctional UV oligomer (EM3101), 0.2 g of waterborne polyurethane acrylate (611A-85), 0.4 g of polyfunctional oligomer (BASF PE55WN), 0.4 g of oleophobic modified titanium sol, 0.7 g of photoinitiator WB-4785, and 0.7 g of sodium dodecylbenzenesulfonate; (6) Place the PAN / TiO2 / coating fiber mat obtained in step (5) into a UV curing machine and cure it at a wavelength of 305 nm and a temperature of 300 mJ / cm. 2 Irradiation under energy conditions for 12 hours completely crosslinks the residual groups, resulting in a membrane; (7) Remove the final separator, test its hydrophilic and oleophobic properties, and assemble the flow battery to further test its battery performance.

[0058] Testing showed that, after coating the flow battery membrane prepared in this embodiment with hydrophilic and oleophobic materials and functional groups, the hydrophilic contact angle of the membrane decreased to 41°, while the oleophobic contact angle increased to 121°. When this membrane was assembled into a sodium polysulfide-bromine flow battery, at a current density of 50 mA / cm², [the following results were obtained]. 2 Under constant current charge and discharge test conditions, the energy efficiency of the battery using this separator is 76.5%.

[0059] Example 8 In this embodiment, the method for preparing the foamed carbon electrode for the flow battery is as follows: (1) Add 5g tetramethoxytitanium, 1g anhydrous ethanol and 1g deionized water to a flask, stir in a water bath at 80°C and keep warm for 12h to obtain nano-titanium particles with a particle size of 600nm.

[0060] (2) Dissolve the nano-titanium particles obtained in step (2) in an ethanol solution to prepare a nano-titanium / ethanol solution with a concentration of 5 g / L. Then add 1 g of perfluorooctyl sulfonyl aminopropyltrimethoxysilane to it and react at 30°C for 1 h to graft the fluoroalkyl chain onto the surface of the nanoparticles and modify the nano-titanium particles. (3) Dissolve 1 g of the modified nano-titanium particles obtained in step (2) in 5 g / L PAN / DMF solvent and stir to prepare an electrospinning solution; (4) The electrospinning solution obtained in step (3) was used to prepare electrospinning PAN / TiO2 fiber mat under the conditions of 12 kV voltage, 5 cm spinning distance and 0.001 mm / min feed rate. (5) The PAN / TiO2 fiber felt obtained in step (4) was placed in a 2.5 wt% dimethyl sulfoxide coating solution of sulfonated polybenzimidazole and reacted at 30°C for 1 hour to obtain PAN / TiO2 / coating fiber felt. The dimethyl sulfoxide coating solution contained 1.5 g of monofunctional UV oligomer (EM3101), 1.5 g of waterborne polyurethane acrylate (611A-85), 1.5 g of polyfunctional oligomer (BASF PE55WN), 1.5 g of oleophobic modified titanium sol, 1.5 g of photoinitiator WB-4785, and 1.5 g of sodium dodecylbenzenesulfonate; (6) Place the PAN / TiO2 / coating fiber mat obtained in step (5) into a UV curing machine and cure it at a wavelength of 255nm and a temperature of 270 mJ / cm. 2 Irradiate for 12 hours under energy conditions to completely crosslink the residual groups; (7) Remove the final separator, test its hydrophilic and oleophobic properties, and assemble the flow battery to further test its battery performance.

[0061] Testing showed that, after coating with hydrophilic and oleophobic substances and functional groups, the hydrophilic contact angle of the flow battery membrane prepared in this embodiment decreased to 23°, while the oleophobic contact angle increased to 154°. When this membrane was assembled into a sodium polysulfide-bromine flow battery, at a current density of 50 mA / cm², [the following results were obtained]. 2 Under constant current charge and discharge test conditions, the energy efficiency of the battery using this separator is 66.7%.

[0062] The results of the examples show that the flow battery separator material prepared by the method of the present invention has good hydrophilicity and oleophobicity after being coated with a series of hydrophilic and oleophobic substances and functional groups, which improves the battery performance of the flow battery and provides a new idea for the development of flow battery separators.

[0063] The embodiments described above merely illustrate specific implementation methods of this application, and while the descriptions are detailed and specific, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the technical solution of this application, and these modifications and improvements all fall within the scope of protection of this application.

[0064] This background section is provided to generally present the context of the invention. The work of the currently named inventors, the work to the extent described in this background section, and aspects of this section that did not constitute prior art at the time of application are neither expressly nor impliedly acknowledged as prior art to the invention.

Claims

1. A method for constructing a hydrophilic and oleophobic membrane surface based on ultraviolet light curing process, characterized in that, The method includes the following steps: (1) Add tetramethoxytitanium, anhydrous ethanol and deionized water to a container, stir and keep warm under water bath conditions to obtain a series of nano-titanium particles with different particle sizes. (2) Dissolve the nano-titanium particles obtained in step (1) in an ethanol solution to prepare a nano-titanium / ethanol solution of a certain concentration; then add perfluorooctyl sulfonyl aminopropyltrimethoxysilane to the nano-titanium / ethanol solution and react at a certain temperature for a period of time to graft the fluoroalkyl chain onto the surface of the nanoparticles to obtain modified nano-titanium particles. (3) Dissolve the modified nano-titanium particles obtained in step (2) in PAN / DMF solvent and stir to prepare an electrospinning solution; (4) Prepare electrospun PAN / TiO2 fiber mat from the electrospun solution obtained in step (3); (5) The PAN / TiO2 fiber felt obtained in step (4) is placed in a dimethyl sulfoxide coating solution containing sulfonated polybenzimidazole for reaction, and PAN / TiO2 / coating fiber felt is obtained after the reaction. (6) The PAN / TiO2 / coating fiber felt obtained in step (5) is placed in a UV curing machine and irradiated to completely crosslink the residual groups, thereby obtaining the hydrophilic and oleophobic membrane.

2. The method for constructing a hydrophilic and oleophobic membrane surface based on ultraviolet light curing process according to claim 1, characterized in that, In step (1), the mass ratio of tetramethoxytitanium, anhydrous ethanol and deionized water is 5~10:1~5:1~5; the temperature of water bath stirring is 30~80℃, and the reaction time is 1~12h; the particle size of the obtained nano-titanium particles is 100~800 nm.

3. The method for constructing a hydrophilic and oleophobic membrane surface based on ultraviolet light curing process according to claim 1, characterized in that, In step (2), the concentration of the prepared nano-titanium / ethanol solution is 1~5 g / L; the mass ratio of perfluorooctylaminopropyltrimethoxysilane to tetramethoxytitanium is 1~10:5~10; the reaction temperature is 30~80℃; and the reaction time is 1~12h.

4. The method for constructing a hydrophilic and oleophobic membrane surface based on ultraviolet light curing process according to claim 1, characterized in that, In step (3), the concentration of the prepared PAN / DMF solvent is 5~20 g / L.

5. The method for constructing a hydrophilic and oleophobic membrane surface based on ultraviolet light curing process according to claim 1, characterized in that, In step (4), the voltage for preparing electrospun PAN / TiO2 fiber felt from the electrospun solution is 12~20 kV, the spinning distance is 5~20 cm, and the feeding speed is 0.001~0.1 mm / min.

6. The method for constructing a hydrophilic and oleophobic membrane surface based on ultraviolet light curing process according to claim 1, characterized in that, In step (5), the concentration of sulfonated polybenzimidazole in the dimethyl sulfoxide coating solution containing sulfonated polybenzimidazole is 2.5 wt%; the reaction temperature is 30~80℃ and the reaction time is 1~12h; the dimethyl sulfoxide coating solution also contains monofunctional UV oligomers, waterborne polyurethane acrylates, multifunctional oligomers, oleophobic modified titanium sol, photoinitiator WB-4785 and sodium dodecylbenzenesulfonate.

7. The method for constructing a hydrophilic and oleophobic membrane surface based on ultraviolet light curing process according to claim 1, characterized in that, In step (6), the conditions for complete cross-linking are: curing wavelength 205-405 nm, curing energy 200-300 mJ / cm², and curing time 1-12 h.

8. A hydrophilic and oleophobic membrane constructed using a UV curing process, obtained by any of the methods described in claims 1-7.

9. A flow battery, characterized in that, The diaphragm as described in claim 8 is used.

10. The flow battery according to claim 9, characterized in that: The flow batteries mentioned include iron-chromium, vanadium-based, zinc-iron, iron-based, zinc-bromine, sodium / bromine polysulfide, titanium-manganese, or organic system flow batteries.

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