Crosslinked polybenzimidazole ion exchange membrane as well as preparation method and application thereof

Abstract

The invention discloses a cross-linked polybenzimidazole ion exchange membrane as well as a preparation method and application thereof. The cross-linked polybenzimidazole ion exchange membrane is a cross-linked polybenzimidazole ion exchange membrane with a three-dimensional grid structure, which is formed by taking polybenzimidazole resin as a cross-linked skeleton and carrying out cross-linking reaction through a cross-linking agent; wherein the cross-linking agent is selected from at least one of halogenated xylene and halogenated dimethylnaphthalene. The cross-linked polybenzimidazole ion exchange membrane has the characteristics of simple preparation method, environment-friendly process and the like. Compared with the original uncrosslinked polybenzimidazole ion exchange membrane, the crosslinked polybenzimidazole ion exchange membrane has higher chemical stability in an alkaline system, the cycle life of a battery is prolonged, meanwhile, the migration problem of an electrolyte solution can be effectively inhibited, and the charge-discharge performance of the battery is improved.

Description

Technical Field

[0001] The present application relates to a crosslinked polybenzimidazole ion exchange membrane, a preparation method thereof and an application thereof, and belongs to the technical field of flow batteries. Background Art

[0002] A flow battery is a new electrochemical energy storage technology. Compared with other energy storage technologies, it has the advantages of high energy conversion efficiency, flexible system design, large storage capacity, free site selection, deep discharge ability, safety, environmental protection, low maintenance cost, etc., and can be widely used in renewable energy power generation energy storage such as wind energy and solar energy, emergency power supply systems, standby power stations, and peak shaving and valley filling of power systems. The alkaline zinc-iron flow battery is considered to be a flow battery with great development potential due to its high safety, good stability, long life (life > 15 years), low cost, etc.

[0003] The battery separator is an important component in the flow battery, which plays a role in blocking the positive and negative electrolyte solutions and providing a transport channel for hydroxide ions. The chemical stability and ion conductivity of the membrane will directly affect the electrochemical performance and service life of the battery; therefore, it is required that the membrane has a high ion conductivity and a low surface resistance, and at the same time, it should also have good chemical stability and a low cost. The membrane materials currently used at home and abroad are mainly Nafion membranes developed by DuPont Company of the United States. Nafion membranes have excellent performance in terms of electrochemical performance and service life, but due to their high price, especially the disadvantages such as poor ion conductivity when applied to alkaline zinc-iron flow batteries, the industrial application of this membrane is limited. At the same time, another major type of membrane material commonly used at present is the anion exchange membrane, which has excellent ion conductivity in the alkaline system, but its chemical stability is poor, which limits its application under long-term operation conditions of the battery.

[0004] Currently, the polybenzimidazole ion exchange membranes used in the developed and used alkaline flow batteries all have the problem of low stability of polybenzimidazole in the alkaline system, resulting in the aging and degradation of the membrane material after long-term operation of the battery, and further affecting the cycle stability of the battery.

[0005] After crosslinking with halogenated xylene or halogenated dimethylnaphthalene, the polybenzimidazole resin has a three-dimensional network structure of its chain segments. At the same time, due to the introduction of a large number of benzene rings, the rigidity of its chain segments is enhanced, thus significantly increasing its chemical stability, and thus the purpose of improving the cycle stability of the battery under long-term operation can be achieved. Summary of the Invention

[0006] The object of the present invention is to overcome the problems existing in the polybenzimidazole ion exchange membrane for alkaline system flow batteries, and to provide a cross-linked polybenzimidazole ion exchange membrane for alkaline system flow batteries, which can greatly improve the chemical stability of the ion exchange membrane, so as to obtain a diaphragm material with extremely low cost and suitable for alkaline system flow batteries.

[0007] According to one aspect of the present application, there is provided a cross-linked polybenzimidazole ion exchange membrane, wherein the cross-linked polybenzimidazole ion exchange membrane uses a polybenzimidazole resin as a cross-linked skeleton, and after cross-linking reaction with a cross-linking agent, a cross-linked polybenzimidazole ion exchange membrane with a three-dimensional grid structure is formed;

[0008] Wherein, the cross-linking agent is selected from at least one of halogenated xylene and halogenated dimethylnaphthalene.

[0009] Optionally, in the cross-linked polybenzimidazole ion exchange membrane, the mass ratio of the polybenzimidazole resin to the cross-linking agent is 10:1 to 1:1.

[0010] Optionally, the mass ratio of the polybenzimidazole resin to the cross-linking agent is 5:1 to 2:1.

[0011] Optionally, the mass ratio of the polybenzimidazole resin to the cross-linking agent independently selects any value from 10:1, 8:1, 5:1, 3:1, 1:1 or the range value between any two of the above.

[0012] Optionally, the thickness of the cross-linked polybenzimidazole ion exchange membrane is 10 to 100 μm.

[0013] Optionally, the halogenated xylene is selected from at least one of 1,2-dichlorotoluene, 1,3-dichlorotoluene, 1,4-dichlorotoluene, 1,4-dibromotoluene, 1,3-dibromotoluene, 1,2-dibromotoluene;

[0014] The halogenated dimethylnaphthalene is selected from at least one of 1,3-dichloromethylnaphthalene, 1,4-dichloromethylnaphthalene, 1,3-dibromomethylnaphthalene, 1,4-dibromomethylnaphthalene.

[0015] Another aspect of the present application provides a preparation method of the above-mentioned cross-linked polybenzimidazole ion exchange membrane, and the preparation method includes:

[0016] (1) Stir solution I containing polybenzimidazole resin and cross-linking agent, react to obtain cross-linked polybenzimidazole resin;

[0017] (2) Mix the cross-linked polybenzimidazole resin obtained in step (1) with organic solvent II, stir II to obtain a casting solution;

[0018] (3) Coating the casting solution obtained in step (2) on a substrate and drying to obtain the crosslinked polybenzimidazole ion exchange membrane;

[0019] Wherein, the crosslinking agent is selected from at least one of halogenated xylene and halogenated dimethylnaphthalene.

[0020] Optionally, in step (1), the mass ratio of the polybenzimidazole resin to the crosslinking agent is 10:1 to 1:1.

[0021] Optionally, the mass ratio of the polybenzimidazole resin to the crosslinking agent is independently selected from any value of 10:1, 8:1, 5:1, 3:1, 1:1 or the range value between any two of the above.

[0022] Optionally, in the solution containing the polybenzimidazole resin and the crosslinking agent, the concentration of the polybenzimidazole resin is 1 to 20 wt%.

[0023] Optionally, the concentration of the polybenzimidazole resin is independently selected from any value of 1 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt% or the range value between any two of the above.

[0024] Optionally, the halogenated xylene is selected from at least one of 1,2-dichlorotoluene, 1,3-dichlorotoluene, 1,4-dichlorotoluene, 1,4-dibromotoluene, 1,3-dibromotoluene, 1,2-dibromotoluene;

[0025] The halogenated dimethylnaphthalene is selected from at least one of 1,3-dichloromethylnaphthalene, 1,4-dichloromethylnaphthalene, 1,3-dibromomethylnaphthalene, 1,4-dibromomethylnaphthalene.

[0026] Optionally, the solution containing the polybenzimidazole resin and the crosslinking agent further includes an organic solvent I, and the organic solvent I is selected from at least one of acetonitrile (MeCN), N-methylpyrrolidone (NMP), dimethylformamide (DMF), and dimethyl sulfoxide (DMSO).

[0027] Optionally, the temperature of the first stirring is 40 to 120 °C;

[0028] The time of the first stirring is 6 to 48 h.

[0029] Optionally, the temperature of the first stirring is independently selected from any value of 40 °C, 60 °C, 80 °C, 100 °C, 120 °C or the range value between any two of the above.

[0030] Optionally, the time of the first stirring is independently selected from any value of 6 h, 12 h, 18 h, 24 h, 36 h, 42 h, 48 h or the range value between any two of the above.

[0031] Optionally, in the casting solution, the concentration of the crosslinked polybenzimidazole resin is 5 to 50 wt%.

[0032] Optionally, the concentration of the crosslinked polybenzimidazole resin is independently selected from any value of 5 wt%, 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt% or the range value between any two of the above.

[0033] Optionally, the organic solvent II is selected from at least one of dimethyl sulfoxide (DMSO), N,N-dimethylacetamide (DMAC), N-methylpyrrolidone (NMP), and dimethylformamide (DMF).

[0034] Optionally, the temperature of the second stirring is 20 to 100 °C;

[0035] The time of the second stirring is 0.5 to 10 h.

[0036] Optionally, the temperature of the second stirring is independently selected from any value of 20 °C, 40 °C, 60 °C, 80 °C, 100 °C or the range value between any two of the above.

[0037] Optionally, the time of the second stirring is independently selected from any value of 0.5 h, 2 h, 4 h, 6 h, 8 h, 10 h or the range value between any two of the above.

[0038] Optionally, the drying temperature is 20 to 80 °C;

[0039] The drying time is 0.5 to 48 h.

[0040] Optionally, the drying temperature is independently selected from any value of 20 °C, 40 °C, 50 °C, 60 °C, 80 °C or the range value between any two of the above.

[0041] Optionally, the drying time is independently selected from any value of 0.5 h, 12 h, 24 h, 36 h, 48 h or the range value between any two of the above.

[0042] Optionally, the substrate is selected from a PET substrate or a glass plate.

[0043] Optionally, the coating method is selected from at least one of the casting method, the scraping method, the spraying method, and the spin coating method.

[0044] As a specific embodiment, the crosslinked polybenzimidazole composite ion exchange membrane is prepared according to the following process:

[0045] (1) Dissolve polybenzimidazole resin and a crosslinking agent in a certain proportion in one or more solvents selected from MeCN, NMP, DMF, and DMSO, and stir well at a temperature of 40 - 120 °C for 6 - 48 h to allow sufficient reaction. Then remove the solvent to obtain crosslinked polybenzimidazole resin. The concentration of polybenzimidazole resin as the main chain is between 1 - 20 wt%.

[0046] (2) Dissolve the crosslinked polybenzimidazole resin prepared in step (1) in an organic solvent, and stir well at a temperature of 20 - 100 °C for 0.5 - 10 h to prepare a casting solution. The concentration of the crosslinked polybenzimidazole resin is between 5 - 50 wt.%.

[0047] (3) Coat the casting solution prepared in step (2) on a PET substrate or a glass plate to form a casting solution coating with a certain thickness, and then place it in an oven at a temperature of 20 - 80 °C for 0.5 - 48 h to completely volatilize the organic solvent in the mixed casting solution, obtaining a dry crosslinked polybenzimidazole resin ion exchange membrane.

[0048] In another aspect of the present application, there is provided an application of the above crosslinked polybenzimidazole ion exchange membrane in an alkaline system flow battery, where the pH of the positive electrolyte and / or the negative electrolyte of the alkaline system flow battery is > 7.

[0049] The beneficial effects that can be produced by the present application include:

[0050] 1) Compared with ordinary polybenzimidazole ion exchange membranes, the crosslinked polybenzimidazole ion exchange membrane has higher chemical stability in an alkaline system. The alkaline system flow battery assembled with it has a higher cycle life, and at the same time can effectively inhibit the migration problem of the electrolyte solution and improve the charge and discharge performance of the battery.

[0051] 2) For the crosslinked polybenzimidazole ion exchange membrane prepared in the present application, the resin ratio can be adjusted and the thickness can be controlled. By adjusting the above parameters, the controllable adjustment of battery performance can be achieved.

[0052] 3) The present application expands the types and application ranges of membrane materials for alkaline system flow batteries.

[0053] 4) The crosslinked polybenzimidazole ion exchange membrane has the characteristics of simple preparation method and environmental protection process. Detailed Embodiments

[0054] The present application will be described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0055] Unless otherwise specified, the raw materials in the embodiments of the present application are all purchased through commercial channels.

[0056] Example 1

[0057] Dissolve 10 g of polybenzimidazole resin in 100 mL of acetonitrile solvent, then add 2 g of 1,3-dichlorotoluene thereto, stir at 80 °C for 24 h, then remove the solvent and wash the product. Dissolve the obtained crosslinked polybenzimidazole resin in 50 mL of DMAc, stir at 50 °C for 2 hours to prepare a casting solution, wherein the mass fraction of the crosslinked polybenzimidazole resin in the casting solution is 20 wt%. Coat the prepared casting solution on a glass plate by the doctor blade method, place it on a heating platform at 50 °C and let it stand for 24 hours to form a uniform and dense crosslinked polybenzimidazole ion exchange membrane. The thickness of the obtained crosslinked polybenzimidazole ion exchange membrane is 40 μm.

[0058] Performance test: Assemble an alkaline zinc-iron flow battery using the prepared composite ion exchange membrane, where the electrode is carbon felt, the bipolar plate is a graphite plate, and the effective area of the membrane is 48 cm 2 , and the current density is 80 mA cm -2 , the concentration of hydroxide ions in the electrolyte is 3 mol L -1 , the concentration of zincate ions is 0.5 mol L -1 , and the concentration of ferrocyanide ions is 1 mol L -1 . The Coulombic efficiency (CE) of the assembled alkaline zinc-iron flow battery is 98.8%, the voltage efficiency (VE) is 89.1%, and the energy efficiency (EE) is 88.0%. The battery life > 2000 cycles.

[0059] Example 2

[0060] The process and conditions are the same as those in Example 1, except that the crosslinking agent is changed to 5 g of 1,4-dibromonaphthalene, the solvent used is changed to NMP, and the crosslinking reaction conditions are changed to stir at 60 °C for 36 h, with other conditions remaining unchanged. After testing, the Coulombic efficiency (CE) of the battery is 99.2%, the voltage efficiency (VE) is 89.0%, and the energy efficiency (EE) is 88.3%. The battery life > 2000 cycles.

[0061] Example 3

[0062] The process and conditions are the same as those in Example 1, except that the crosslinking agent is changed to 2 g of 1,4-dichlorotoluene and 2 g of 1,2-dichlorotoluene, the solvent used is changed to DMSO, and the crosslinking reaction conditions are changed to stir at 100 °C for 18 h, with other conditions remaining unchanged. After testing, the Coulombic efficiency (CE) of the battery is 98.6%, the voltage efficiency (VE) is 89.7%, and the energy efficiency (EE) is 88.4%. The battery life > 2000 cycles.

[0063] Example 4

[0064] The process and conditions are the same as those in Example 1, except that the crosslinking agent is changed to 2 g of 1,4-dichlorotoluene and 2 g of 1,4-dibromotoluene, the solvent used is changed to DMAc, and the crosslinking reaction conditions are changed to stirring at 80 °C for 18 h, with other conditions remaining unchanged. After testing, the Coulombic efficiency (CE) of the battery is 98.7%, the voltage efficiency (VE) is 89.5%, and the energy efficiency (EE) is 88.3%. The battery life > 2000 cycles.

[0065] Example 5

[0066] The process and conditions are the same as those in Example 1, except that the crosslinking agent is changed to 1 g of 1,3-dichlorotoluene, with other conditions remaining unchanged. After testing, the Coulombic efficiency (CE) of the battery is 95.5%, the voltage efficiency (VE) is 88.2%, and the energy efficiency (EE) is 84.2%. The battery life > 1500 cycles.

[0067] Example 6

[0068] The process and conditions are the same as those in Example 1, except that the reaction conditions are changed from stirring at 80 °C for 24 h to stirring at 40 °C for 6 h, with other conditions remaining unchanged. After testing, the Coulombic efficiency (CE) of the battery is 96.1%, the voltage efficiency (VE) is 87.7%, and the energy efficiency (EE) is 84.3%. The battery life > 1500 cycles.

[0069] Comparative Example 1

[0070] The performance test process is the same as that in Example 1. The difference compared with Example 1 is that the membrane is replaced with an uncrosslinked polybenzimidazole ion exchange membrane, with other conditions remaining unchanged. The Coulombic efficiency of the battery is 96.7%, the voltage efficiency is 85.5%, and the energy efficiency is 82.7%. The battery life < 300 cycles.

[0071] Comparative Example 2

[0072] The performance test process is the same as that in Example 1. The difference compared with Example 1 is that the membrane is replaced with a crosslinked polyimide ion exchange membrane, with other conditions remaining unchanged. The Coulombic efficiency of the battery is 84.2%, the voltage efficiency is 72.1%, and the energy efficiency is 60.7%. The battery life < 100 cycles.

[0073] Compared with the uncrosslinked polybenzimidazole ion exchange membrane, the battery assembled with the crosslinked polybenzimidazole ion exchange membrane has a significantly improved cycle stability, and at the same time, the Coulomb efficiency and energy efficiency of the battery also increase to a certain extent. This shows that the crosslinked polybenzimidazole ion exchange membrane obtained after the crosslinking reaction has greatly enhanced chemical stability in the alkaline system, thereby significantly increasing the cycle life of the battery; at the same time, because the polymer chain segments form a three-dimensional network after crosslinking, the swelling of the membrane material in the solution is reduced, the ion crossover is decreased, and the ion selectivity of the membrane material is improved. Therefore, the battery performance also improves to a certain extent.

[0074] The ion exchange membrane effectively improves the ion selectivity of the membrane and blocks the crossover of alkali metal ions in the electrolytes at both the positive and negative electrodes; at the same time, the cycle life of the battery is significantly increased, indicating that the composite ion exchange membrane effectively inhibits the formation of zinc dendrites, alleviates the self-discharge phenomenon of zinc metal in the electrolyte, and increases the cycle life of the battery.

[0075] As described above, these are only several embodiments of the present application and do not impose any form of limitation on the present application. Although the present application is disclosed with preferred embodiments as above, it is not intended to limit the present application. Any person skilled in the art, without departing from the scope of the technical solution of the present application, makes some changes or modifications using the technical content disclosed above, which are equivalent to equivalent embodiments and all fall within the scope of the technical solution.

Claims

1. A crosslinked polybenzimidazole ion exchange membrane, characterized in that, The crosslinked polybenzimidazole ion exchange membrane uses polybenzimidazole resin as a crosslinked skeleton, and after crosslinking reaction with a crosslinking agent, a crosslinked polybenzimidazole ion exchange membrane with a three-dimensional network structure is formed; Among them, the crosslinking agent is selected from at least one of halogenated xylene and halogenated dimethylnaphthalene.

2. The crosslinked polybenzimidazole ion exchange membrane according to claim 1, characterized in that, In the crosslinked polybenzimidazole ion exchange membrane, the mass ratio of polybenzimidazole resin to the crosslinking agent is 10:1 to 1:1; Preferably, in the crosslinked polybenzimidazole ion exchange membrane, the mass ratio of polybenzimidazole resin to the crosslinking agent is 5:1 to 2:

1.

3. The crosslinked polybenzimidazole ion exchange membrane according to claim 1, characterized in that, The thickness of the crosslinked polybenzimidazole ion exchange membrane is 10 to 100 μm.

4. The crosslinked polybenzimidazole ion exchange membrane according to claim 1, characterized in that, The halogenated xylene is selected from at least one of 1,2-dichlorotoluene, 1,3-dichlorotoluene, 1,4-dichlorotoluene, 1,4-dibromotoluene, 1,3-dibromotoluene, and 1,2-dibromotoluene; The halogenated dimethylnaphthalene is selected from at least one of 1,3-dichloromethylnaphthalene, 1,4-dichloromethylnaphthalene, 1,3-dibromomethylnaphthalene, and 1,4-dibromomethylnaphthalene.

5. A method for preparing the crosslinked polybenzimidazole ion exchange membrane according to any one of claims 1 to 4, characterized in that, The preparation method includes: (1) Stir solution I containing polybenzimidazole resin and a crosslinking agent, react to obtain crosslinked polybenzimidazole resin; (2) Mix the crosslinked polybenzimidazole resin obtained in step (1) with organic solvent II, stir II to obtain a casting solution; (3) Coat the casting solution obtained in step (2) on a substrate, dry to obtain the crosslinked polybenzimidazole ion exchange membrane; Among them, the crosslinking agent is selected from at least one of halogenated xylene and halogenated dimethylnaphthalene.

6. The preparation method according to claim 5, characterized in that, In step (1), the mass ratio of polybenzimidazole resin to the crosslinking agent is 10:1 to 1:1; In the solution containing polybenzimidazole resin and a crosslinking agent, the concentration of the polybenzimidazole resin is 1 to 20 wt%; Preferably, the halogenated xylene is selected from at least one of 1,2-dichlorotoluene, 1,3-dichlorotoluene, 1,4-dichlorotoluene, 1,4-dibromotoluene, 1,3-dibromotoluene, and 1,2-dibromotoluene; The halogenated dimethylnaphthalene is selected from at least one of 1,3-dichloromethylnaphthalene, 1,4-dichloromethylnaphthalene, 1,3-dibromomethylnaphthalene, and 1,4-dibromomethylnaphthalene; Preferably, the solution containing polybenzimidazole resin and a crosslinking agent further includes organic solvent I, and the organic solvent I is selected from at least one of acetonitrile, N-methylpyrrolidone, dimethylformamide, and dimethyl sulfoxide; Preferably, the temperature of stirring I is 40 to 120 °C; The time of stirring I is 6 to 48 h.

7. The preparation method according to claim 5, characterized in that, In the casting solution, the concentration of the crosslinked polybenzimidazole resin is 5 to 50 wt%.

8. The preparation method according to claim 5, characterized in that, The organic solvent II is selected from at least one of dimethyl sulfoxide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethylformamide; Preferably, the temperature of stirring II is 20 to 100 °C; The time of stirring II is 0.5 to 10 h.

9. The preparation method according to claim 5, characterized in that, The temperature of drying is 20 to 80 °C; The time of drying is 0.5 to 48 h; Preferably, the substrate is selected from a PET substrate or a glass plate; Preferably, the coating method is selected from at least one of the casting method, the doctor blade method, the spraying method, and the spin coating method.

10. Use of the crosslinked polybenzimidazole ion exchange membrane according to any one of claims 1 to 4 in an alkaline system flow battery, characterized in that, In the alkaline system flow battery, the pH of the positive electrolyte and / or the negative electrolyte is > 7.