Proton-conducting polymer composite and method for its production

Abstract

FIELD: polymer production.SUBSTANCE: invention relates to polymer proton-conducting composite materials, in particular to film materials used in solid polymer fuel cells, and a method for producing them. A proton-conducting polymer composite is proposed for use in solid fuel cells, containing aromatic polyetheretherketone (PEKFFF) as a binding polymer matrix with the following formula:, where n=303÷313 in the amount of 36-44 wt.%, and bifunctional cationite KU-1 in the amount of 56-64 wt.%.EFFECT: new polymeric proton-conducting composite material and a simple, cost-effective method for producing it.2 cl, 5 ex

Description

[0001] The invention relates to proton-conducting polymer composites, in particular to film materials used in solid polymer fuel cells, and a method for producing them.

[0002] One of the simplest ways to create proton-conducting polymer systems is to create composite materials containing a binding polymer matrix and ionic components. Such components typically contain polar functional groups that abstract a proton (sulfonic acid, phosphoric acid, carboxyl, and other polar groups).

[0003] A method for producing proton-conducting polymer membranes is known (Patent RU 2285557, B01D71 / 38 (2006.01), B01D71 / 52 (2006.01).

[0004] The patent uses polyvinyl glycidyl diester of ethylene glycol with proton-conducting sulfonic acid groups in the side chain.

[0005] The disadvantages of the method are the multi-stage nature of the polymer electrolyte production and the possibility of interaction of the resulting sulfonic acid fragments with the hydroxyl groups of polyvinyl alcohol included in the polymer base, which leads to a decrease in the sulfonic acid groups in the polymer and, accordingly, to a decrease in the proton conductivity of the membrane.

[0006] In the following work [Trofimov B.A., Ermakova T.G., Volkova L.I., Kuznetsova N.P., Myachina G.F., Chipanina N.N., Kanitskaya L.V., Vakulskaya T.I., Rokhin A.V., Mognonov D.M. Plastics. 2007. No. 1. Pp. 20-23], membranes based on a copolymer of vinyl chloride and vinyl butyl ether containing sulfonic acid groups are described.

[0007] The disadvantages of composites are low proton conductivity values ​​(from 1.0×10 -4 cm / cm up to 3.0×10 -4 Cm / cm) at room temperature.

[0008] In the article [Shagaeva N.S., Sultangareev R.G., Orkhokova E.A., Prozorova G.F., Dmitrieva G.V., Dambinova A.S., Stenina I.A., Yaroslavtsev A.B. Membranes and membrane technologies. 2011. No. 3. pp. 213-219] proton-conducting polymer membranes based on modified polyvinyl chloride containing sulfonic acid groups are proposed.

[0009] The disadvantages of the method are the low values ​​of proton conductivity of membranes from 2.0×10 -4 cm / cm up to 5.9×10 -3 Cm / cm in the temperature range of 45-100°C and unsatisfactory physical and mechanical properties.

[0010] In patent RU 2643960, IPC B01D71 / 30 (2006.01); C08J5 / 22 (2006.01); H01M8 / 02 (2006.01) proposes proton-conducting polymer membranes with high conductivity based on modified polyvinyl chloride containing sulfonic acid fragments, vinyl chloride units and dehydrochlorinated vinyl chloride units modified by sulfonation of polyvinyl chloride with chlorosulfonic acid in a 1,2-dichloroethane medium in the presence of a heat stabilizer (barium salts) at a temperature of 60°C and vigorous stirring for 1 hour. The method for producing proton-conducting polymer membranes includes sulfonation of polyvinyl chloride with chlorosulfonic acid in the presence of a heat stabilizer, followed by rolling a mixture based on modified polyvinyl chloride containing sulfonic acid fragments, vinyl chloride units and dehydrochlorinated vinyl chloride and dioctyl phthalate units at a temperature of 100-120°C for 20 minutes.The method for producing proton-conducting polymer membranes involves rolling a mixture based on a sulfonated polymer and dioctyl phthalate in a ratio of 1:0.4 for 20 minutes.

[0011] The disadvantages of the proposed method include the need for a sulfonation reaction of polyvinyl chloride, which releases highly toxic hydrogen chloride, and the need to roll the mixture at 100-120°C. Furthermore, vinyl chloride units containing single carbon-carbon bonds will not have sufficiently high thermal properties.

[0012] RU Patent No. 2284214 proposes proton-conducting composite polymer membranes. The matrices used are copolymers of 1-vinyl-1,2,4-triazole with fluoroalkyl methacrylates, as well as aliphatic and aromatic polybenzimidazoles and polyamidobenzimidazoles; the thermosetting plastics are epoxy-containing copolyimides, polyaminoimide resin, pyrimidine-containing oligo-bis-itaconimide, and poly-bis-benzotriazoleimide resin. Polymer films were formed from the resulting mixed solutions, followed by thermal curing or UV irradiation, and then doped by immersion in aqueous solutions of orthophosphoric acid of varying concentrations. Thermal curing of the films is carried out by prolonged heating at 100÷230°C.

[0013] The disadvantages of this method are the multi-stage nature, the lengthy time required, and the need to use high temperatures.

[0014] Various types of composite additives (in particular, cation exchangers and anion exchangers) are known in the art and are used to create polymer proton-conducting systems. For example, in patent application No. 148906, IPC C08J5 / 22, heterogeneous ion-exchange membranes are produced by rolling a mixture of ion exchangers and a polymer binder on hot rollers, followed by reinforcing them with synthetic fabrics or fibers in a press.

[0015] Reinforcement of membranes using this method is carried out in a hydraulic press at a temperature of 130-140°C for 30-40 minutes.

[0016] Such prolonged exposure to high temperatures leads to the degradation of ion exchange groups of ionites and a drop in the electrochemical properties of the membranes.

[0017] Furthermore, preparing membranes for pressing (preparing and assembling packages) is a very labor-intensive process requiring the work of several people, which significantly complicates and lengthens the technological process and, ultimately, increases the cost of the membranes.

[0018] In patent application No. 462848, IPC C08J1 / 34, a method for producing heterogeneous ion-exchange membranes by rolling a mixture of ion exchangers and a polymer binder with subsequent reinforcement of the membranes on a drum vulcanization press is proposed.

[0019] The essence of this method is that a rolled membrane film consisting of crushed resin and polyethylene is coated on both sides with a reinforcing material (for example, nylon, lavsan) and is fed by a conveyor to the surface of a drum press heated to 130-140°C, rotating at a speed of 0.10-0.15 m / min, and at a pressure of 5-10 kgf / cm 2 the membrane is reinforced.

[0020] The disadvantages of this method are insufficient mechanical strength, as well as low electrochemical properties, which makes their application in industry difficult.

[0021] The closest analogue is the production of ion-exchange membranes according to the patent RU No. 2314322, C08J5 / 22 “Method for producing heterogeneous ion-exchange membranes”, published 10.01. 2008, Bulletin No. 1.

[0022] In the patent, heterogeneous ion-exchange membranes are produced by rolling a mixture of an ion exchange resin and a polymer binder, feeding the mixture to a calender, the roller temperature of which is 125-135°C. A reinforcing material is applied to the surface of the calendered film, and then a material is applied on top of this to prevent the film from sticking to the heating surface of the press. Reinforcement is carried out at a temperature of 140-150°C and a pressure of 180-200 kgf / cm. 2 and a conveyor belt speed of 80-90 m / h. The reinforcement time is determined by the specified speed. The reinforced membrane then passes through a bath filled with water, where it is freed from the anti-stick material.

[0023] The disadvantages of this method are the length of time, the need to use high temperatures and pressure, the complexity of the technological cycle for obtaining the composite, as well as the low temperature properties of the product.

[0024] The object of the present invention is to develop a new proton-conducting polymer composite and a simple, economical method for producing the same.

[0025] The stated objective is achieved by the fact that a heterogeneous polymer composite is obtained by mixing aromatic polyetheretherketone (PEEKFF) based on 9,9-bis-(4-hydroxyphenyl)-fluorene, 4,4'-difluoro-diphenyl-ketone and hexafluorobenzene of the formula:

[0026]

[0027] where n = 303÷313, and the bifunctional cation exchange resin KU-1. The reduced viscosity of PECFF, measured for a 0.5% solution in chloroform, is 0.79 dl / g. The bifunctional cation exchange resin KU-1 contains different acid groups (-SO3H, -OH), obtained by copolycondensation of phenol and p-phenolsulfonic acid with formaldehyde:

[0028]

[0029] The following ratios (mass%) of components in the composite are taken:

[0030] KU-1 56÷64 PEKFFFF 44÷36

[0031] Proton-conducting polymer composite samples were prepared by dissolving PECFF in chloroform to obtain polymer matrix solutions with concentrations of 4.62–5.58 wt.%, swelling KU-1 in chloroform, mixing them to form a homogeneous suspension, and removing the solvent. Chloroform grade "Ch" was used.

[0032] Below are examples illustrating the method for producing a proton-conducting polymer composite.

[0033] Example 1. Obtaining a proton-conducting polymer composite consisting of 44 wt.% PECFF and 56 wt.% KU-1.

[0034] Place 0.88 g of PECFFF in glass beaker 1 and add 10 ml of chloroform (5.58 wt% solution). Place 1.12 g of KU-1 cation exchanger in glass beaker 2 and add 10 ml of chloroform. Leave the beakers for 1 hour, until the PECFFF is completely dissolved and the KU-1 cation exchanger swells. Then, pour the contents of beakers 1 and 2 into glass beaker 3 and stir for three minutes until a homogeneous suspension is formed. Then, pour the mixture into a Petri dish previously placed under a fume hood. After complete evaporation of the solvent, a film proton-conducting polymer composite is obtained.

[0035] The specific conductivity of the composite, measured by the four-probe Van der Pauw method at a frequency of 500 Hz, reaches 1.56⋅10 -1 Cm / cm. The temperature at which mass loss begins, according to thermogravimetric analysis, is 458°C.

[0036] Example 2. Obtaining a proton-conducting polymer composite consisting of 42 wt.% PECFF and 58 wt.% KU-1.

[0037] Place 0.84 g of PECFFF in glass beaker 1 and add 10 ml of chloroform (5.34 wt% solution). Place 1.16 g of KU-1 cation exchanger in glass beaker 2 and add 10 ml of chloroform. Leave the beakers for 1 hour, until the PECFFF is completely dissolved and the KU-1 cation exchanger swells. Then, pour the contents of beakers 1 and 2 into glass beaker 3 and stir for three minutes until a homogeneous suspension is formed. Then, pour the mixture suspension into a Petri dish previously placed under a fume hood. After complete evaporation of the solvent, a film proton-conducting polymer composite is obtained.

[0038] The specific conductivity of the composite, measured by the four-probe Van der Pauw method at a frequency of 500 Hz, reaches 1.57⋅10 -1 Cm / cm. The temperature at which mass loss begins, according to thermogravimetric analysis, is 459°C.

[0039] Example 3. Obtaining a proton-conducting polymer composite consisting of 40 wt.% PECFF and 60 wt.% KU-1.

[0040] Place 0.8 g of PECFF (5.1 wt% solution) in glass beaker 1 and add 10 ml of chloroform. Place 1.2 g of KU-1 cation exchanger in glass beaker 2 and add 10 ml of chloroform. Leave the beakers for 1 hour, until the PECFF is completely dissolved and the KU-1 cation exchanger swells. Then, pour the contents of beakers 1 and 2 into glass beaker 3 and stir for three minutes until a homogeneous suspension is formed. Then, pour the mixture into a Petri dish previously placed under a fume hood. After complete evaporation of the solvent, a film proton-conducting polymer composite is obtained.

[0041] The specific conductivity of the composite, measured by the four-probe Van der Pauw method at a frequency of 500 Hz, reaches 1.58⋅10 -1 Cm / cm. The temperature at which mass loss begins, according to thermogravimetric analysis, is 459°C.

[0042] Example 4. Obtaining a proton-conducting polymer composite consisting of 38 wt.% PECFF and 62 wt.% KU-1.

[0043] Place 0.76 g of PECFFF () in glass beaker 1 and add 10 ml of chloroform. Place 1.24 g of KU-1 cation exchanger in glass beaker 2 and add 10 ml of chloroform. The beakers are left for 1 hour, waiting for the PECFFF to completely dissolve and the KU-1 to swell. Then, pour the contents of beakers 1 and 2 into glass beaker 3 and stir for three minutes until a homogeneous suspension is formed. Then, pour the mixture into a Petri dish, previously placed in a fume hood. After complete evaporation of the solvent, a film proton-conducting polymer composite is obtained.

[0044] The specific conductivity of the composite, measured by the four-probe Van der Pauw method at a frequency of 500 Hz, reaches 1.58⋅10 -1 Cm / cm. The temperature at which mass loss begins, according to thermogravimetric analysis, is 460°C.

[0045] Example 5. Obtaining a proton-conducting polymer composite consisting of 36 wt.% PECFF and 64 wt.% KU-1.

[0046] Place 0.72 g of PECFFF in glass beaker 1 and add 10 ml of chloroform (4.62 wt% solution). Place 1.28 g of KU-1 cation exchanger in glass beaker 2 and add 10 ml of chloroform. Leave the beakers for 1 hour, until the PECFFF is completely dissolved and the KU-1 cation exchanger swells. Then, pour the contents of beakers 1 and 2 into glass beaker 3 and stir for three minutes until a homogeneous suspension is formed. Then, pour the mixture suspension into a Petri dish previously placed under a fume hood. After complete evaporation of the solvent, a film proton-conducting polymer composite is obtained.

[0047] The specific conductivity of the composite, measured by the four-probe Van der Pauw method at a frequency of 500 Hz, reaches 1.60⋅10 -1 Cm / cm. The temperature at which mass loss begins, according to thermogravimetric analysis, is 461°C.

[0048] As can be seen from the above information, the samples of proton-conducting polymer composite exhibit fairly high values ​​of specific conductivity and thermal stability.

[0049] The technical result of the proposed invention consists in the development of a new proton-conducting polymer composite and a simple, economical method for producing it.

Claims

1. A proton-conducting polymer composite used in solid fuel cells, containing aromatic polyetheretherketone (PEEKFF) of the formula as a binder polymer matrix: where n=303÷313, and bifunctional cationite KU-1, and the quantitative ratio of the components corresponds, mass%: KU-1 56÷64 PEKFFFF 44÷36 2. A method for producing a proton-conducting polymer composite according to paragraph 1, comprising mixing a polymer matrix and a cation exchanger, characterized in that a PECFF polymer matrix is ​​used in the form of solutions with mass concentrations of 4.62÷5.58%, and a bifunctional cation exchanger KU-1 is used as the cation exchanger, wherein the swelling of KU-1 is carried out in chloroform for 1 hour, after which the components are mixed until a homogeneous suspension is formed, followed by evaporation of the solvent.

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