CN101174701A - Hydrophilic polymers and their use in electrochemical cells - Google Patents

Abstract

A hydrophilic cross-linked polymer obtainable by copolymerisation of hydrophobic and hydrophilic monomers that give a cross-linked hydrophilic polymer on polymerisation; a monomer including a strongly ionic group; and water is useful as the membrane in an assembly that can be used in an electrolyter or fuel cell. More generally, a membrane electrode assembly comprises electrodes and an ion-exchange membrane which comprises a hydrophilic polymer including a strongly ionic group. A method for producing a membrane electrode assembly comprising electrodes and an ion-exchange membrane, comprises introducing between the electrodes a material or materials from which the membrane can be formed, and forming the membrane in situ.

Description

Hydrophilic polymer and the application in electrochemical cell thereof

The application is that application number is dividing an application of 02819812.3 application.

Technical field

The hydrophilic polymer that the present invention relates to conduct electricity and in for example application in the fuel cell of electrolytic cell and electrochemical cell.

Background technology

In the electrolytic cell, the input electric energy produces to purify learns conversion.Thereby the common trait in conventional electrolysis pond need to be a large amount of electric energy of input to drive cell reaction with enough speed.The usefulness of propping up the battery of sening as an envoy to of this electric energy reduces.

Electrochemical cell particularly fuel cell can be membrane electrode assembly (MEA) form.Solid polymer electrolyte fuel cell MEAs typically has sandwich construction, comprises (i) proton exchange membrane (PEM), the (ii) collecting electrodes and the (iii) electricity-catalyst layer of every side.Thereby PEM relies on and comprises embedding cation position permission anion transmission and carry out work.Similarly, solid polymer electrolyte can comprise fixing anionic site, and it can the prioritised transmission cation.Therefore, mention that below PEM is not an exclusiveness.

Said structure is assembled by discrete elements, becomes MEA by heating with pressurized adhesion, be assemblied between gas manifold before, make total sealing prevent that gas leakage (and intersection) is with the formation monocell.This method is very complicated, PEM and be commonly used for (ii) and the intrinsic cost of the carbon tissue that scribbles catalyst (iii) is the main production cost of fuel cell.

The restriction of PEM fuel cell performance is the management of water, in use to keep the abundant hydration of PEM film.Hydrogen becomes electricity to obtain product water with oxygen conversion, and it appears at the oxygen electrode place.Make this film keep operating state, described film must have enough water penetrations so that product water distributes and prevents the local exsiccation of this film.Become dry and to cause overheated and catastrophic failure (even may cause the hydrogen/oxygen intersection and might blast).

The PEM device only relies on the character work of making film.When the electrolytic cell, add that power and water produces oxygen and hydrogen; During as fuel cell, produce with hydrogen and oxygen (or air).

Existing P EM material for example Nafion is made up of noncrosslinking fluorinated polymer (mainly being PTFE), and described polymer has the ion activity of comprising position (to be generally SO ₃) side chain.Described SO ₃The position provides hydrophily.Must keep these materials and additional water (providing) hydration, to operate by hydration fuel gas.They can thin slice (10-30 μ m is thick) form obtain, and are used to be assembled into battery (voltage 1V), thereby are assembled into battery pack (typically 100 unit).

Can be by single MEAs production battery pack (stack).Since must produce dividually each MEA connect then superimposed in heaps, so the production battery pack is required great effort very much.

The hydrophilic polymer that high water content can be arranged is known.Water content determines its character.Its electrical property is by the character decision of hydration solution.For example, some hydrophilic material such as HEMA (methacrylic acid 2-hydroxyl ethyl ester) and MMA-VP (methyl methacrylate-vinyl pyrrolidone) are known as contact lens material in biomedical sector, but they do not have intrinsic electrical property.Therefore, if hydration in deionization-distillation (DD) water, resulting polymers is good resistor, if but hydration in acid or alkaline solution, this material then is that good conductor described hydrated polymer when the electroactive solution of flush away just recovers non-conductive system.

US-A-4036788 discloses the anionic hydrogel that obtains by heterocycle N-vinyl monomer, the monomer that contains sulfonic acid and crosslinking agent copolymerization.Can in the presence of dissolving in wherein water-soluble solvent, described monomer carry out polymerization; Obtain described polymer with the organogel form, therefrom remove nonaqueous solvents by distillation, evaporation or washing.Be immersed in and cause swelling in the water, the soft, flexible material that the control that obtains can be used for reclaiming alkalescence or cationic materials or be used for this material from aqueous medium discharges.

WO-A-01/49824 discloses by not containing sulfonic monomer, containing the polymer that sulfonic monomer and nonessential crosslinking agent polymerization obtain.This polymer is applicable to the connection and the growth of cell and is applicable to bio-medical instrument and artificial limb.They have very high expansion rate.

The element of this specification is open before its priority.Referring to for example Delegate Manualof the Fifth Grove Fuel Cell Symposium, 22-25 September 1997.These elements do not provide is enough to make those of ordinary skill can realize the information of following invention.

Summary of the invention

The present invention is based on following discovery to small part: can produce particularly PEM material (but comprising positive from material, as previously described) of amberplex (IEM) material based on hydrophilic polymer (promptly can absorb and transmit the polymer of water inherently in its whole molecular structure).This material that is modified and comprises the strong ion part of sulfonic acid or other can prepare by radiation or the thermal polymerization polymerisation in bulk by initial monomers or prepolymer system.Ying Zaishui or other liquid carry out polymerization so that system is even under existing.

According to a first aspect of the invention, a kind of can be further with the part of water hydration fill in advance (pre-extended) hydrophilic polymer can by monomer and solvent for example the polar liquid copolymerization obtain, described monomer comprises the monomer that contains strong ion radical.Preferably make resulting polymers crosslinked.Not with the polymer of the present invention of water hydration or IEM material can be in use for example in the fuel cell that produces water by hydration (comprise the hydration of any degree for this manual, comprise hydration to greatest extent).

The invention still further relates to a kind of hydrophily IEM material, comprise the hydrophilic polymer matrix and be retained in the interior molecule that comprises strong ion radical of matrix.The ion activity molecule can be retained in the matrix by steric hindrance and/or chemical bonding.Can make described crosslinked polymer.

Control ground is introduced electroactive position and is created in the pure water material from hydration and conduction.This material can be used as electrochemical membrane, also has the character that makes it to be applicable to biology sensor and electro-optical device.

The ability of producing the IEM material by polymerized in-situ allows a step production battery pack.Can also produce polymer-electrode hybrid system, wherein polymeric separator plates connects and enlarges the active surface area of electrode or electrode catalyst system.

According to a second aspect of the invention, the MEA that is used for electrochemical reaction comprises for example PEM of electrode and IEM, and wherein said assembly comprises and is used for liquid state or gaseous reaction component are transferred to electrode and/or limit passage by what electrode spread out of.Described assembly can also comprise described catalyst for reaction, and it preferably contacts with described passage.

If two or multiple reactant be liquid or gas, more passage can be provided.All passages all can be whole or in part in film; For example can limit by film and matrix on every side or backing material.

The accompanying drawing summary

Figure 1A and 1B illustrate the known method of the compound MEAs of preparation and the step of new method.

Fig. 2 A-2D illustrates the product of the present invention of controllable system parameter respectively.

Fig. 3-5 illustrates the schematic embodiment of second aspect present invention.

Fig. 6 is conductivity and IEC form function as polymer a curve chart.

Fig. 7 is IEC and the water absorption rate curve chart as the crosslink density function.

Fig. 8 is for embodying the cross section of product of the present invention.

Fig. 9 and 10 embodies the curve chart of the cell voltage of product of the present invention to electric current.

Figure 11 illustrates the polarization behavior that embodies the present invention and play the cMEA of fuel galvanic action.

Figure 12 embodies the curve chart of the voltage of the present invention and the cMEA that plays the fuel galvanic action to the duration of runs under the constant current of 10mA.

The description of preferred embodiment

Hydrophilic copolymers can form by the polymerisation in solution of monomer mixture, and described monomer mixture typically comprises:

(a) hydrophobicity/structure comonomer such as MMA, AN (acrylonitrile), polyamide or TRIS and

(b) hydrophily but nonessential electroactive comonomer such as VP, HEMA etc.

Not only there had been hydrophilic monomer but also existed hydrophobic monomer can allow to be independent of hydraulics character and controlled electrical property, because can be fit to the different requirements of film and film/catalyst/electrode interface.The relative quantity may command swellability of these monomers, and to make described product be rigidity or firm and resilient.

Can utilize γ-radiation or thermal radiation to form cross-linked material.For example, can utilize ionising radiation, the 90MeV γ-radiation as from cobalt 60 source needn't add crosslinking agent in the case.But, also can control final material properties by adding following material:

(c) chemical cross-linking agent such as allyl methacrylate or ethylene glycol dimethacrylate and

(d) chemical initiator such as AIBN (azodiisobutyronitrile) or azo bicyclohexane formonitrile HCN.

If make described material heat initiation and crosslinked, then above component (c) and (d) essential by described method.

The present invention relates to make this hydrophilic material change into electroactive system (cation or anionic) by adding following material:

(e) be retained in the interior electric active molecule of described hydrophilic polymer matrix; Or

(f) electroactive comonomer.

Described electroactive component can be based on acid sulfonic acid (SO for example ₃), Phosphoric acid or phosphonic acid, or alkali for example provides compound such as KOH, NaOH or the aluminium hydroxide of OH ion, or ethlyene dichloride base benzyltrimethylammon.um.Preferred monomer is 2-acrylamido-2-methyl isophthalic acid-propane sulfonic acid (AMPS), styrene sulfonic acid (SA), vinyl sulfonic acid (VA) or SOMA.Also can make component (a) or (b) modification so that its also play component (f).

Can replace chemical bonding or electric active molecule (e) is retained in the matrix by steric hindrance by steric hindrance and chemical bonding.In hydrophilic polymer, add swelling solution (for example ethanol) and can produce swelling bigger when making water.The ion activity molecule that will be dissolved in swelling solution by diffusion is exchanged into water, thereby described polymer will shrink described molecule is trapped in the matrix.50: observe this effect when 50MMVA-VP copolymer and ionic molecule are dissolved in ethanol.

Available the method is introduced one or more ion activity molecule in the matrix.Thereby the molecule that generates than the bigger molecule of the molecule of holding back by steric hindrance and/or cause introducing of reacting between the molecule that makes the activation of described material can cause introducing by γ-radiation subsequently bonds with polymeric matrix and reacts.

In any type of PEM system in the used solid polymer electrolyte, ionic conduction (C _i) should be than electron conduction (C _e) much higher.For successful operation requires C _e/ C _iRatio is less than 0.1.

Product of the present invention can by described monomer and water or component (f) dissolves in wherein and the polymerization production of other liquid that other component is can be molten with it mixed.The related situation of water is fully understood as yet, but under the state of acid or alkaline solution, it obviously plays comonomer and reconciles acid or alkali introducing partly in the described cross-linked polymer structures.After the polymerization, can remove some or all water, but rehydrated may not produce dry before products obtained therefrom.

About described material the item that should consider comprise its hydrophily (for being independent of electrical property control water and gas permeability) and crosslinked (for stability) thereof; The use of sulfonic acid, phosphoric acid etc.; Be used for the use of the basic side chain of alkaline fuel cell; Make described polymer have electroactive part with water or alcohol, described polar solvent is as (unexpectedly) comonomer.As described polymer, it is preferred that AN-VP adds AMPS, but other combination of monomers that is fit to comprises MMA-VP; MMA-HEMA; With combination of AMPS＜VSA＜SSA＜TSA etc.

For produce evenly, consistent and isotropic polymer, described each component should be dissolved mutually or be dissolved each other mixed mutually.For example, the part that contains sulfonic acid generally is insoluble to other preferred comonomer.Having found to make a kind of effective way that has the sulfonic acid component in the final monomer mixture is to make described acid water-soluble (or alcohol or other polar liquid that is fit to) and described solution is mixed in the monomer mixture.Final SO ₃Content (thereby electrical property) especially depends on the molten mixed ability of the acid solution of sulfonic acid part solubility, other comonomer and the given volume mark in water, reaches the stability and the polymerizing power thereof of gained mixture.

Found that the AN-VP system can be molten mixed with the aqueous acids of a large amount of volume fractions.Can be effectively with accounting for the aqueous solution of final monomer mixture 50% as comonomer at most.

When being subjected to γ-radiation, described monomer mixture can become sticky, and forms firm but resilient cross-linked material then, for example under the accumulated dose of 0.1-3.0Mrad.

Replace making described monomer directly aggregate into the polymer of wanting, can form prepolymer earlier, for example (i) by with lower accumulated dose (typically＜0.05Mrad, dose rate～0.01Mrad/hr) γ-radiation, or (ii) by at suitable UV initator for example 2, there is time UV radiation in 2-dimethoxy-2-phenyl acetophenone.Then with (iv) additional γ-radiation (for example accumulated dose of 1.0-3.0Mrad) or (v) suitable initator for example in the presence of AIBN or the azo bicyclohexane formonitrile HCN thermal polymerization make described prepolymer (relative easy operating) change into final solid cross-linked form.

Described final material is partially pre-hydrated typically, comprises the big water gaging as initial comonomer, therefore is expanded to abundant hydration and does not produce the normal after-expansion degree relevant with the IEM material.This obviously reduces hydration stress, thereby often relevant with Nafion base MEAs IEM and the layering between the catalyst/electrode structure are obviously reduced.

About polymerization the item that should consider comprise:

(a) temperature is to the influence of polymerization, for example avoids bubbling with chemical initiator and/or utilizes the polymerization of γ-radiation when making the dissolubility of the freezing controllable flow sex change of monomer and any adjacent materials;

(b) adopt a step (with heat, UV or γ-radiation) or two steps (by prepolymer, with heat/heat, γ-radiation/γ-radiation, heat/γ-radiation, γ-radiation/heat or UV etc.; With

(c) control of the rheology of described monomer mixture or prepolymer performance is to strengthen the wetting/infiltration of described filling process and control catalyst or electrode paper (during use).

About the conversion/production of film/MEA/ battery pack the item that should consider comprise:

(a) by utilizing γ-radiation in the monomer one step production;

(b) by utilizing thermal initiator to avoid bubble in the monomer one step production;

(c) adopted for two steps,, be rheology control or special interface performance by prepolymer.

Can adopt " lost wax process " (comprise and use ice), for example avoid the manifold overflow.Described manifold or MEA can use the recovery of shape polymer.Release coating described to limit " film " can be set on electrode network.

Wish that the used polymer of the present invention all shows maximum conductivity and IEC value under any given absorptivity.Volumetric expansion during balance absorptivity decision hydration, thereby decision mechanical performance and the compound MEA of the gained possibility that layering damages will be because of hydration or hydration change the time.

Another ideal performance of described polymer is an absorptivity, can control electrical property and machinery/hydraulics character independently.Preferred material allows controllably to change IEC and conductivity values, and for example 2 times, the while is at the scope inner control water absorption rate of 3 (30% to 85% wet weight marks).

One of the appropriate methodology of selection principal monomer example comprises with two kinds of sulfonic acid concentrations prepares sample with (AN or MMA or PA)+VP+ (each of AMPS, VS, SA and SOMA).Prepare these samples and make it polymerization as crosslinking agent with allyl methacrylate by γ-radiation.Screen at its conductivity, mechanical performance and water absorption rate in DD water.By the method initial various may the prescription (totally 24 kinds) dwindled into the most preferred system based on AN+VP+AMPS, below use the just explanation for example of this system.Selecting the main cause of AN+VP+AMPS to be that at first this system demonstrates the conductivity value all higher than other any combination of monomers, may be that next is mechanical performance because the limit of miscibility of described monomer and water base sulfonic acid solutions is fine.Under all situations, mechanical performance (tensile strength and tearing strength) all with the polymer equilibrium water absorption become (along with water absorption rate increases, elasticity improve and tensile strength reduce), but find to use AN that maximum tension and the tearing strength that becomes with water content is provided.

Electrical property when as expected, having found in DD water hydration SO directly and in the polymer ₃The concentration at position is relevant.In fact, described sulfonic acid partly is insoluble to any main monomer, and is water-soluble and add and to introduce this system in the AN+VP mixture by making described material.Thereby, SO ₃The maximum of concentration is by component separation or precipitation water+SO before takes place ₃The molten mixed limit of+monomer is determined.Obtain gratifying limit when using AN.

Found that equilibrium water absorption (in DD water) depends on three parameters: (a) concentration of main hydrophilic body VP; (b) auxiliary VP plays the hydrophilic body effect and as the SO of additive ₃Concentration; (c) concentration of crosslinking agent allyl methacrylate (AMA).Equilibrium water absorption is along with VP concentration increases, SO ₃Concentration increases and crosslinker concentration reduces and increases.

Comprise for improving the item that electrode/the catalyst/membrane interface should be considered:

(a) comprise catalyst (integer catalyzer) in the polymerization process;

(b) comprise carbon fiber (overall electrode) in the polymerization process;

(c) comprise composite catalyst/electrode in the film;

(d) utilize extended surface, allow differently to optimize catalyst/electrode/ionomer surface in every side of fuel cell or electrolytic cell.

As previously described, the present invention can produce composite construction (comprising electrode-catalyst-film-catalyst-electrode) by one-step method.This means and obviously deviate from any existing production method.If use traditional carbon paper electrode-catalyst, described monomer or prepolymer system can be infiltrated gas is reduced to the transmission of catalyst layer; For reducing any side effect, described paper base material should be thin as far as possible, for example comprises 0.35mg/cm ²The ETEK TPGH-030 carbon tissue of platinum.

The production of single composite fuel cell unit preferably includes makes " model " with described two electrode assemblies that scribble catalyst, for described film is reserved the gap, introduce described " film " with polymer/prepolymer form, finish described production process with single radiation method then.This is shown among Figure 1B, and it illustrates successively as the cavity between the catalyst-electrode of wall 12 11; Fill described cavity and radiation thereof with hydrophilic monomer liquid 13; Form integral battery door with " film " 14, one steps of gained polymerization.This should with conventional method shown in Figure 1A contrast, it comprises successively and obtains catalyst-electrode 15 and PEM material 16 dividually; With described material assembling and alignment; And sealing, heating with compression so that catalyst-electrode contact.

Because described material is by solution (or prepolymer) polymerization, so they provide many alternative production approach.For finished films, comprising:

(a) utilize fiber reinforcement (1D or 2D), 1D when controlling final hydration or 2D expand;

(b) do not strengthen but twin shaft prestress, with the control layering when preventing to contact of expanding with catalyst/electrode structure;

(c) in the top layer, mix catalyst and/or carbon fiber,, form final MEA effectively but do not rely on conventional catalyst/electrode structure to form chemism and gaseous conductor interface; With

(d), enlarge polymer/catalyst reaction thing surface that performance may strengthen thereby produce surface area on " reticulate pattern " surperficial top-pour polymer injection surface.

Referring to Fig. 2: Fig. 2 A illustrates simple aggregation thing 21 of the present invention; Fig. 2 B and 2C illustrate the polymer that one-sided and bilateral is distributed with catalyst 22; Fig. 2 D additionally illustrates electrode 23.Described electrode can be flooded by hydrophilic material whole or in part.

For the finished product MEA that uses conventional catalyst electrode paper, method comprises:

(a) one-step method of utilizing γ-radiation to begin by monomer, as shown in fig. 1;

(b) one-step method of utilizing thermal initiator to begin by monomer; With

(c) be used for prepolymer stage of rheology control or particular interface performance.

For the on-the-spot compound MEA that forms described film (thereby contact with it) in the space between catalyst and electrode member, one-step method comprises:

(a) make liquid monomer or prepolymer polymerization;

(b) make the polymerization in the carrier that is fit to of monomer in the solution or prepolymer;

(c) solution polymerization process;

(d) with solution form pouring liquid polymer, extraction solvent is so that polymer deposition;

(e) add the polymer that is fit to powder type, with described powders compression or sintering; With

Described material cured when (f) polymer that add to be fit to molten condition, described MEA enabling temperature.

These methods of producing MEA are not limited to the parallel plane system.Availablely provide or improve the composite film material that the material soaking of ion migration and/or hydraulics character forms by method (e).Described impregnating agent can add fashionable or come into force after membrane material polymerization, crosslinked or gelling at it.Also can make compound MEA by combination two single faces " partly " battery in the thickness of described film.This available other polymerization is realized.

The production method of the many battery pack of finished product comprises any of the production method (a) to (g) that is used for compound MEA, also comprises:

(a) one-step method of utilizing γ-radiation to begin by monomer, as shown in fig. 1;

(b) one-step method of utilizing thermal initiator to begin by monomer; With

(c) two-step method of the prepolymer by being used for rheology control or particular interface performance.

Described method also is not limited to the parallel plane system.

In the many battery pack of preparation, may wish to prevent that monomer from overflowing gas manifold structure (this is with the work of overslaugh battery pack).Replace using the conventional material that blocks, the water wetted material of available prestress blocks manifold passage, and this material will recover removable shape (sintered powder or change of shape).Also available " (smart) of intelligence " salvage material metal or constructed in plastic material manifold itself.Make battery and fill monomer, polymerization forms film, makes described manifold material activation and the recovery gas passage.

The film of MEA device can comprise non-electroactive hydrophilic polymer matrix, but comprises the strong ionic species that is retained in the matrix; It is electroactive that this totally has described membrane material.

For illustrating, can between two smooth PTFE plates, form compound MEA, use the weaving of used monomer inertia or the porous polyester interlayer of non-woven form are made maintenance separation between the electrode.(under blanket of nitrogen) introduces monomer mixture in described gap then, fills spacer material, with battery compression to limit described thickness of structure.Mould is placed in the excess monomer and radiation, for example by two-step method (low dosage/dose rate, high dose rate then is to finishing).

Between filling and polymerization period, described polyester layer keeps making described two paper electrodes to separate.In addition, because general hydrophilic material is isotropically expanded when hydration, so the introducing of this reinforcing material is quite effective to the area expansion of control hydrophilic polymer film during hydration.Therefore, though the expansion of described material, effect is to have increased the thickness of described enhanced film rather than its area.Before between clamping and the solid plate at fuel cell test device of pincers, this can effectively prevent the layering in hydro-combination process of described compound system.

This production method provides the electrode-membrane-electrode composite construction that runs through mutually with membrane material, when described membrane material extends beyond electrode zone, forms effective sealing gland when being clamped between the manifold of fuel cell test device.

(usually in polyester reinforcement) can form bubble in the described composite material.Can carry out sonicated to mould after the filling and adopt the two-stage polymerization that reduces temperature rise effect between polymerization period that this problem is minimized.Can before the fuel cell of packing into, make abundant hydration of MEA ' s and test, guarantee gas cross can not take place with nitrogen.

In a second aspect of the present invention, exist transmission channel that reactive component can more effectively be contacted with any catalyst with electrode in the described assembly.Can be cast in the described film by " dewax " or " intellectual material " insertion and produce passage, advantageous cross sections is circular.Described assembly can also comprise the discrete manifold structure that limits its physical restriction, and passage can be embedded within the physical restriction of film and assembly.Electrode and any catalyst material can be applied to after passage forms in the reactant channel or in " dewax " or " intellectual material " method process and be cast into channel surface.

Available flexible material for example plastic material limits the edge of MEA and provides electricity and/or gas partitions.Available carbon fibre fabric is made electrode, and described fabric can flood one deck catalyst.At reactant is in the fuel cell of hydrogen or oxygen, and described catalyst typically is platinum.Similarly, the electrolytic cell that is used for water electrolysis generally comprises platinum electrode.When electrode is a self-supporting or during by " dewax " support structure, then can cast a plurality of batteries, because the formation of film own forms the structure of battery within it.

Described membrane material preferably includes the polymer that contains strong ion radical, as previously described.

The embodiment of the present invention that comprises passage shown in Fig. 3 to 5.The common trait of these embodiments is electrode 32 (typically being the carbon fibre fabric of dipping one deck catalyst) and curtain coating amberplex 36.

Fig. 3 illustrates an assembly, wherein uses flexible plastic 31 (for example polyethylene) limitation unit edge, and the corresponding recess 35 that inserts opposite side by projection on one side 34 limits described interval.Reactant is carried dividually by passage 33a and 33b; A kind of reactant infeeds by passage 33a, and another kind of reactant infeeds by passage 33b.This staggered electrode surface area that causes to passage 33a and 33b increases than conventional flat electrode assembly.

Fig. 4 illustrates an assembly, and wherein reactant is an oxygen in middle atmosphere 41.In the case, one of constraint element shown in Figure 3 is replaced by gas permeable material 42 to strengthen to the reaction interface delivering oxygen.Another reactant is carried by passage 43.

Fig. 5 illustrates the electrode 32 by " dewax " support structure.Infeed reactant by passage 33a and 33b as shown in Figure 3.Among this embodiment, four independently battery be cast in the film other three batteries of the film area limiting between each battery.If described assembly is a fuel cell, then equal the output current of seven independent batteries from the output current of Battery Interconnecting Cables 51.

Following examples explanation the present invention.

Abbreviation used herein and material are as follows:

Hydrophobic monomer:

Methyl methacrylate (MMA)

Acrylonitrile (AN)

Methacryloxypropyl three (trimethylsiloxy) silane (TRIS)

Methacrylic acid 2,2,2-trifluoro ethyl ester (TRIF)

Hydrophilic monomer:

Methacrylic acid (MA)

Methacrylic acid 2-hydroxyl ethyl ester (HEMA)

Ethyl acrylate (EA)

L-vinyl-2-pyrrolidone (VP)

Acrylic acid 2-methyl esters (PAM)

Phthalic acid monomethyl acryloyl-oxy ethyl ester (EMP)

Sulfuric acid ethyl-methyl ammonium acrylate (SEM)

-SO ₃The H part:

Toluenesulfonic acid (TSA)

1-methyl isophthalic acid-benzimidazolyl-2 radicals-sulfonic acid

Isethionic acid, sodium salt

The own sulfonic acid of 1-, sodium salt

Methylol sulfonic acid

The monomer that comprises the sulfonic acid position that is used for copolymerization:

2-acrylamido-2-methyl isophthalic acid-propane sulfonic acid (AMPSA)

Vinyl sulfonic acid (VSA)

Styrene sulfonic acid (SSA)

Methacrylic acid 2-sulphur ethyl ester (SOMA)

3-sulfopropyl methacrylic acid, sodium salt (SPM)

Embodiment 1

Raw material

Acrylonitrile-vinyl pyrrolidone (AN-VP; 1: 1) mix monomer buys, and former state is used.

Methyl methacrylate (MA) is distillation before use (99%Aldrich).

L-vinyl-2-pyrrolidone (VP) (99%Aldrich) is frozen, and use the back that thaws.

Used crosslinking agent be allyl methacrylate (AMA) (98%Acros).

2-acrylamido-2-methyl isophthalic acid-propane sulfonic acid (AM) (99%), vinyl sulfonic acid (sodium salt, the 25wt% aqueous solution) (VSA) and 4-styrene sulfonic acid (SSA) sodium-salt hydrate all available from Aldrich.

It is synthetic that the sulfopropyl Sodium methacrylate is pressed US-A-1299155.

Prescription

Different AM, AMA and the eight kind different solutions of AN-VP in deionized water (DDW) of forming of preparation, as shown in table 1.

Table 1

Sample	Composition weight (g) and %
										AM	％	DDW	％	AMA	％	AN-VP	％	Add up to
	OR	30	14.15	30	14.15	2	0.94	150	70.8										212
1-1.5AOR										3	18.6	3	18.6	0.13	0.82	10	62	16.13
	2-1.5A6X	3	17.86	3	17.86	0.8	4.75	10	59.5										16.8
3-1.5A8X										3	17.58	3	17.58	1.06	6.24	10	58.6	17.06
	4-1.5A10X	3	17.31	3	17.31	1.33	7.67	10	57.7										17.33
5-2Aor										4	22.06	4	22.06	0.13	0.73	10	55.2	18.13
	6-2A4X	4	21.58	4	21.58	0.53	2.87	10	54										18.53
7-2A8X										4	20.98	4	20.98	1.06	5.58	10	52.5	19.06
	8-2A10X	4	20.69	4	20.69	1.33	6.88	10	51.7										19.33

Be used for the preparation of the monomer of radiation polymerization

Make various sulfonic acid be dissolved in distilled water, join then among the AN-VP (1: 1).In mixture, add AMA again, stir.Be dispensed to described solution in the aluminum cell that is lined with PTFE and seal or be dispensed in the container of plastic plate.

Described monomer adding is had in the battery of plane surface base plate, reach the top until monomer from top filling.Then top board is placed on the base plate of filling, two boards is fixed together with G type anchor clamps.Then described plate is vertically put into ultrasonic bath with the bubble of the system of removing 30 minutes, be exposed to γ-radiation with this upright position then.Come the on-the-spot MEA of manufacturing by between two electrodes between two plates, placing a slice before the radiation by the saturated non-textile material of monomer.

The radiation details

One step radiation was carried out 20 hours with the dose rate of 0.125Mrad/hr, and accumulated dose is 2.50Mrad.

Also adopt two step radiation.When described prescription is OR, prompt radiation with 0.01Mrad/hr carry out 29 hours (=0.29Mrad), then with 0.03Mrad/hr secondary radiation 80 hours (=2.40Mrad).When described prescription is 1.5OR, first dosage be with 0.01Mrad/hr carry out 20 hours (=0.25Mrad), second dosage be with 0.03Mrad/hr carry out 6.83 hours (=1.7075Mrad).

In this radiative process, because sample and radiation source are very near, approximately halfway with container Rotate 180 °.This radiation is lower slightly than former sample, is about 2.5Mrad.

Water absorption rate

At room temperature the fragment of described film was soaked in deionized water 24 hours, remove surface water, weigh with the blotting paper drying.Then described film is dried to constant weight in 60 ℃ in vacuum drying oven.Available [(M _h-M _d)/M _h] * 100% is determined water absorption rate, wherein M _hAnd M _dBe respectively the quality of hydration and dry film.

The measurement of ion-exchange capacity

Make (50ml) hydration 24 hours in the solution of film sample HCl (0.1M) at ambient temperature.Blot sample with thin paper then, put into NaOH (0.1M) (50ml), exchange 24 hours.Use three aliquots (10ml) of this NaOH solution of HCl (0.1M) titration then.Make indicator with phenolphthalein.Again sample is blotted with paper, be reentered into HCl (0.1M) and spend the night in (50ml), then sample is put into vacuum drying oven, in drier, cool off in 110 ℃ of dryings 8 hours.

Following calculating IEC:

The molar concentration of exchange back NaOH=[(molar concentration of HCl) * average titer] ÷ 10

Molar concentration changes (X)=(molar concentration of NaOH before the exchange)-(molar concentration of exchange back NaOH)

100ml comprises (X) mol Na ⁺

50ml comprises (X/1000) * 50mol Na ⁺=Y

Y mol Na ⁺Ion and the exchange of Z g dry film

Y/Z＝mol Na ⁺/g

=Y/ (Z * 1000) milliequivalent/gram dry film

The measurement of resistance under different condition and the conductivity

At room temperature measure the resistance of hydrated film with Phillips Model PM 6303 RCL ohmmeters.Sample is blotted with thin paper, be coated with the skim electrode gel then, place between the dried electrode that also scribbles the skim electrode gel.(1cm * 1cm) calculates its conductivity by its thickness and area then.

Also measure the hydration sample (disk of 1.8cm diameter with Solarton SI 1260 electric impedance analyzers; 2.54cm ²) resistance.

The following characteristic of test material of the present invention:

(a) measure equilibrium water absorption by the linear expansion rate of gravimetric analysis and the known dried size sample of measurement;

(b) measure gas permeability with the coaxial oxygen probe (ISO 9913 Part 1) that is designed for biomedical film.Though the accepted method of conventional water wetted material is difficult to accurately measure the material that contains sulfonic acid.But in view of measuring difficulty, be identified and thought reasonably with interior air permeability value in 15% of the air permeability value of the suitable conventional water wetted material of water absorption rate.

(c) thermal conductivity is measured at abundant hydration status with the fast transient thermal conductivity measurement mechanism that G.Mole describes in ERA Report 5231 (1969).Find that the thermal conductivity value is the function of water absorption rate, increase to the 0.58W/m.K (equal pure water thermal conductivity 95%) of 85% water absorption rate material from the 0.45W/m.K of 55% water absorption rate material (equal water thermal conductivity 78%);

(d) ion-exchange capacity is carried out following sample: (i) make piece and with the material sample of membrane material parallel radiation with (ii) take from membrane material sample (seeing below) above " residue " material of MEA body (proper).Make the hydration 24 hours in HCl (0.1M) solution of described material sample.Then sample is placed NaOH (0.1M) exchange 24 hours, the HCl titration of gained NaOH solution.

(e) thermal stability is cleaned with thermogravimetry (TGA) and when hydration.Find that described material is obviously more stable than Nafion when heating: the AN-VP-AMPS copolymer only loses 4% (suitable with Nafion) of its quality under 150 ℃, even is still keeping 42% (surplus of Nafion is 0 under the temperature more than 500 ℃) under 800 ℃.

Be to estimate conductance and IEC value, during the production MEA with another sample radiation of the used monomer mixture of MEA.The IEC value that records described AN-VP-AMPS material depends on definite production method in the scope of 2-3, be equivalent to equivalent in the 300-400 scope.This and Nafion (its IEC is 0.91, and equivalent is 1100) compare highly beneficial.

Make MEA ' s fully hydration in DD water, be installed in the battery do wiper seal with film edge itself.Therefore, the installation of described MEA ' s is very simple, can obtain stable open circuit voltage (OCV) in applying 30 seconds of working gas.Method of testing relates to be set electric current (by electronics load) and measures the gained cell voltage.When each test procedure finishes, measure OCV again and do not have the serious problems of layering or degraded at duration of test to guarantee MEA.

In a word, with vinyl-SA, styrene-SA, the most important thing is 2-acrylamido-2-methyl isophthalic acid-propane-SA its preparing materials, find its conductance and Nafion quite or better, as shown in Figure 6.In addition, use crosslinking agent can be independent of electrical property and control final water absorption rate, as shown in Figure 7.

Water absorption rate during all with hydration is very relevant because expansion rate and machinery are with hydraulics character, and the control proof of above-mentioned parameter can determine also reproducibly to control the performance of gained material effectively.This is shown among Fig. 7, wherein draws out based on the variation with equilibrium water content and AMA consumption of the IEC value of the various polymer formulators of AN+VP+AMPS.If any application-specific needs, obviously can in wide water absorption rate (thereby wide expansion rate, mechanical performance and water penetration) scope, provide the material of given IEC value.

Fig. 8 is the SEM photo of the whole edge cross section of compound MEA under the dried state, and it illustrates reinforcement 81, two electrode paper 82, catalyst 83 and extends beyond the membrane material 84 of electrode zone so that whole sealing gland to be provided.

The result proves that clearly the compound MEA ' s for preparing by a step production method plays the PEM system effectively shown in Fig. 9 (using non-weaving dividing plate) and Figure 10 (using the weaving dividing plate).Dotted line is all represented conventional configurations but is used the result of the MEA of AN-VP-AMPS film under all situations, promptly simply planar film is pressed between the electrode paper.Solid line is the measurement characteristics with the same film material of whole MEA formal construction.Improvement in performance show contact between PEM material and the catalyst fine.Find that described OCV recovers its initial value afterwards in circulation repeatedly (fully hydration simultaneously), shows that described method successfully prevents polymer and catalyst layer and the layering of carbon paper electrode material.Be accompanied by drying and observe film resistance and increase, but this is reversible when rehydrated.

Embodiment 2

Material

Acrylonitrile (distillation) 75g (35.38%)

Vinyl pyrrolidone 75g (35.38%)

2-acrylamido-2-methyl isophthalic acid-propane sulfonic acid 30g (14.15%)

Water (HPLC level) 30g (14.15%)

Allyl methacrylate 2g (0.94%)

Mix

1. acrylonitrile and vinyl pyrrolidone are mixed, and be stored in the airtight container.

2. described slow acid is added in the entry.Constantly stirring described mixture dissolves fully to guarantee described acid.This process may need 20 minutes.

3. step 2 gained mixture is slowly added in the step 1 gained mixture.Importantly in this process, in cold bath, make the cooling of described acrylonitrile-vinyl pyrrolidone mixture, because may produce some heats when beginning to add acid-aqueous mixtures.Stirring described mixture in this process continuously also is important to avoid unexpected heat release.

4. described allyl methacrylate is added in the step 3 gained mixture and fully and stir.

Final mixture can store maximum three weeks and its polymerizing power not had obvious influence in refrigerating plant.

Assembling

For each cMEA, the carbon paper electrode of two appropriate sizes is placed on the both sides of non-textile polyester thin slice.Described carbon paper sheet must be overlapping fully and in the one side towards polyester sheet the platinum plating surface be arranged.Described polyester sheet has double action.The first, prevent that the carbon paper electrode is in contact with one another and short circuit; The second, the swelling behavior during control gained cMEA hydration.Both sides, make and can once make a plurality of cMEA ' s as dividing plate with polyethylene sheets.Single or a plurality of cMEA ' s is placed in the sealable Polythene Bag.

By the syringe that links to each other with thin polyethylene pipe monomer mixture is injected in the bag, the end of described polyethylene pipe is positioned at the bottom of bag.Before the filling, whole assembly is found time, be full of nitrogen from system, to remove aerial oxygen.At the bottom of directly injecting bag, described monomer mixture helps to remove bubble.Remove charge pipe, make bag leave standstill 5 minutes, so that described monomer mixture can infiltrate in the isolated material.Push described bag at last gently, and from liquid, clear away any bubble.Seal bag this moment.

Apply external pressure by two hard polyethylene boards that are fixed together tightly to bag.This presses together assembly, thereby guarantees that the carbon paper electrode remains on the appropriate location and makes gained cMEA ' s thin as far as possible and thickness is even.The savings layer is formed on the excess monomer mixture that extrudes from cMEA ' s bag top under positive pressure.

Polymerization

Make assembly through the γ-radiation treatment of two-stage shown in the table 2.

Table 2

Level	Duration (hr)	Dose rate (Mrad/hr)	Dosage (Mrad)
				A	2.9	0.01	0.29
B	80	0.03	2.40
						Accumulated dose:	2.69

Component level is placed, and the bag " top " that comprises excess monomer apart from radiation source farthest.The distance in assembly centre-to-centre spacing γ-source is determined by dose rate.When dose rate improved, assembly moved to from radiation source nearer but be orientated constant.

Polymerization is an exothermic process, causes volume to reduce about 4%.Optimised so that the slow polymerization of monomer mixture of initial low dose rate and not overheated.The secondary higher dosage is guaranteed complete polymerization.

Described cMEA ' s will stand the dose rate higher than excess monomer near the part in γ-source.Thereby purpose be will be at one end in this way the described excessive monomer mixture of initiated polymerization can work the work that replenishes the savings layer and reduce in order to the volume that compensates process therewith and accompany.Believe that this method reduces the interior interstitial possibility of cMEA ' s in the polymerization process.

Also can be by thermal-initiated polymerization.This need add the initator (as AIBN) that is fit in monomer mixture.The requirement of initator typically is 2% weight (being 3g for above listed amount promptly) of AN-VP mixture.

This mixture is at room temperature with a lot of days of polymerization.System temperature raises can shorten polymerization time.Volume contraction causes producing in the key area possibility in space when assembly center initiated polymerization can reduce because of polymerization.This can be by realizing at assembly top center application point thermal source.

The separation of cMEA ' s and hydration

Described Polythene Bag is cut, take out cMEA ' s assembly.Described cMEA ' s can be easy to peel off from polyethylene separator.But monomer mixture may ooze out and polymerization around separator edge, makes it to be bonded together.In the case, cutting away this zone from the edge is easier to separate.Must be noted that when mobile not make cMEA ' s bending, because the carbon paper electrode is quite crisp.

After the separation, cMEA ' s can be put into another more sealable Polythene Bag that deionized waters are arranged.Described bag must be enough greatly to allow cMEA ' s to expand in hydro-combination process.

Described polyester isolated material restriction cMEA lateral expansion in hydro-combination process, thus cause described volume to increase most thickness increases that are.This has the benefit that reduces carbon paper-membrane interface stress, and the possibility of layering is reduced.

The act as a fuel test of battery of cMEA

Cell evaluation cMEA can act as a fuel in being applicable to the system of single MEA.The element of system for use in carrying is in the case:

1. two graphite manifolds, its area is bigger than described cMEA.One side of two manifolds all is processed with gas passage, and its area coverage equates with the area that cMEA goes up carbon paper.MEA is clamped between the manifold, and this assembly is called fuel cell.

2. the pipeline that the hydrogen that is fit to make controllable pressure and oxygen link to each other with the gas passage of each manifold.

3. the voltmeter in parallel with fuel cell.

4. can be guided out the electronics load in parallel of user's rated current with fuel cell.

CMEA is suitably placed between the manifold thus two manifolds on gas passage and carbon paper overlapping.Bolt by each angle is fixed together manifold.The film and the manifold that extend beyond carbon paper form sealing gland, because cMEA thickness even (do not resemble conventional MEA ' s and need add sealing mechanism).

When the both sides of cMEA supply of hydrogen and oxygen, observe voltage.Start described electronics load, can derive the electric current that increases, with respect to the polarization characteristic of cell voltage mapping with definite cMEA from fuel cell.The results are shown among Figure 11.Figure 12 illustrates further result.

CMEA is as the test of electrolytic cell

Identical with the test of the battery that acts as a fuel, cMEA is fixed between two manifolds, with the nitrogen wash gas passage to remove any residual hydrogen and oxygen.Capillary is linked to each other with gas inlet and outlet on two manifolds, add water gassy passage.When applying voltage master (2.5V) at the manifold two ends, see from the gas passage of two manifolds by the capillary bubble of emerging.Observe with manifold that power cathode links to each other in produce more gases.Since stoichiometry this with the negative pole releasing hydrogen gas positive pole to emit oxygen consistent.

Collect the gas sample that negative pole produces with syringe, by being designed for the Drager pipe of identifying hydrogen.The result is a positivity, proves that cMEA can be used as electrolytic cell, produces hydrogen and oxygen when being subjected to voltage.

Make cMEAR return the fuel cell experiments device then, reruned 15 hours.Evaluation result shows, as electrolytic cell, carries out preliminary treatment and can strengthen the act as a fuel running of battery of cMEA.

Embodiment 3

The method of enumerating more than the repetition, but replace AMPSA with ethlyene dichloride base benzyltrimethylammon.um (BV), thus introduce the cation position.

Test this material, find to have when in the identical test device, measuring under the same conditions than the obvious higher conductivity of Nafion (improving 30%).

Material component is shown in Table 3.

Table 3

AN(g)	VP(g)	X(g)	BV(g)	AMPSA(g)	Water (g)	Z(g)
							18.75	18.75	0.5	7.5	0	7.5	0.75

Claims (23)

1. a membrane-electrode assemblies comprises electrode and amberplex, and described amberplex comprises the hydrophilic polymer that contains strong ion radical.

2. a membrane-electrode assemblies that is used for electrochemical reaction comprises electrode and amberplex, and described assembly comprises and is used for that liquid state or gaseous reaction component are transferred at least one electrode and/or at least one limits passage by at least one electrode spreads out of.

3. the assembly of claim 2, wherein said ion exchange material comprises the polymer that contains strong ion radical.

4. claim 1 or 3 assembly, the molecule that wherein contains described ion radical physically is trapped in the described polymer.

5. the assembly of aforementioned any claim comprises catalyst.

6. the assembly of claim 5 comprises defined passage at least one claim 2, and wherein said at least one passage allows described reactive component is transferred to described catalyst.

7. hydrophilic cross-linking polymer produces the hydrophobic and hydrophilic monomer of cross-linked hydrophilic polymer, the monomer that comprises strong ion radical and water copolymerization acquisition in the time of can be by polymerization.

8. the polymer of claim 7 has the cation position.

9. the polymer of claim 7 has the anionic site.

10. the polymer of each of claim 7 to 9 has to be not more than 85% water absorption rate.

11. the polymer of each of claim 7 to 10, wherein said hydrophobic monomer are acrylonitrile.

12. the polymer of each of claim 7 to 11, wherein said hydrophilic monomer are vinyl pyrrolidone.

13. the polymer of each of claim 7 to 12 is crosslinked.

14. the polymer of claim 13, wherein said monomer comprises independent crosslinking agent.

15. the polymer of each of claim 7 to 14, wherein said polymerization comprise that γ-radiation or heat cause.

Any feature of requirement 7 to the 15 16. assembly of each of claim 1 to 6, wherein said polymer are had the right.

17. the assembly of each of claim 1 to 6 and 16 is the fuel cell form.

18. the assembly of each of claim 1 to 6 and 16 is the electrolytic cell form.

19. the assembly of each of claim 1 to 6 and 16 to 18 is the battery pack form.

20. a production method that comprises the membrane-electrode assemblies of electrode and amberplex is included in and injects the material and the described film of on-the-spot formation that can form described film between the electrode.

21. the method for claim 20, wherein said film is a polymer, forms described film and comprises compositing monomer or prepolymer polymerized in-situ.

22. the method for claim 21, wherein said film assembly are each of claim 1 to 6 and 16.

23. the method for each of claim 20 to 22, wherein said film assembly are each of claim 17 to 19.

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