TW200820483A - Proton exchange membrane of direct methanol fuel cell and manufacturing method thereof - Google Patents

Abstract

This invention provides a proton exchange membrane of a direct methanol fuel cell, comprising a proton exchange membrane. The proton exchange membrane has a first surface and a second surface, each surface having a polyelectrolyte multilayer membrane which is prepared by alternately arranging at least a layer of cation polyelectrolyte layer and at least a layer of anion polyelectrolyte layer. The manufacturing method of the proton exchange membrane of the direct methanol fuel cell comprises following steps of (1) washing a proton exchange membrane; (2) soaking the proton exchange membrane in a cation polyelectrolyte solution with an adequate concentration, and washing the surface of the proton exchange membrane and removing the proton exchange membrane after a specific soaking time; (3) soaking the proton exchange membrane in an anion polyelectrolyte solution with an adequate concentration, and washing the surface of the proton exchange membrane and removing the proton exchange membrane after a specific soaking time; (4) repeating step (2) and step (3) for several times, thereby obtaining a proton exchange membrane of a direct methanol fuel cell.

Description

200820483 IX. Description of the Invention: [Technical Field] The present invention relates to a proton exchange membrane for a direct methanol fuel cell and a method for producing the same, and in particular to a proton exchange membrane surface modification technique for manufacturing A method for proton exchange membranes of direct methanol fuel cells and finished products thereof. W [First collapse technology] _ The existing power generation system, firepower, hydraulic power, nuclear energy, etc., mainly based on firepower and nuclear power generation, but both have doubts about environmental pollution, and the use of nuclear power plants in the next few years Years have arrived, 'is a secret service is still a domain, coupled with the recent increase in Wei Yi, so the development of this source has become an important issue. At present, the fourth-generation power generation technology fuel cell has been widely researched and developed. The fuel cell (Fuel (10), FC) is a chemical power generation device, which is different from the battery seen in the scale. Direct conversion of chemical energy into electrical energy. It does not pass the heat engine process, so it is not limited by the _Kano cycle. 'Energy conversion efficiency is high (40~60%); environmental impact is small, almost no nitrogen oxides and sulfur oxides are emitted; carbon dioxide reduction is also better than traditional power generation surface Less than 4G%, 'because fuel cell power generation does not burn', so the power generation efficiency is higher than that of conventional power generation; plus • make Kelai _ as energy, so there will be no power failure and charge and discharge issues, and With low pollution, low noise and small size, it is a superior alternative energy source. Because of these outstanding advantages, the research and development of fuel cell technology has attracted the attention of governments and large companies, and is considered to be the clean, high-efficiency power generation technology preferred by the 21st generation. According to the type of desolvation, the fuel cell can be divided into the following five categories: -= two = one 200820483 (1) alkaline fuel cell (alkaline fUel cell, AFC) - using potassium hydroxide as electrolyte; (7) phosphoric acid fuel cell (phosphoric acid fuel cell Cell, PAFC) - using a linonic acid solution as an electrolyte; (3) a proton exchange membrane fuel cell (PEMFC) containing a so-called direct methanol fuel cell (DMFC) Direct use of liquid methanol as a fuel supply source without recombining methanol, gasoline and natural gas through a recombiner to extract hydrogen for power generation; (4) Molten carbonate fuel electric & (m〇lten carb〇nate fhel cell, MCFC ) - Dissolve carbonate as electrolyte; (5) Solid oxide fuel cell (so · 〇 6 6 fine 1 ceIl, S 〇 pc) - mainly using dioxins as electrolytes. The above five fuel cells have attracted the most attention in the development of proton exchange membrane fuel cells (pEMFC), especially direct methanol fuel cells, which have low temperature electricity generation, low fuel component risk, low electricity generation structure, low corrosion, and volume. It is small, light, and easy to carry, and has commercial value and is attracting attention from all walks of life. The structure of direct methanol_battery is similar to that of the general electrochemical cell. It is also composed of two electrodes, the anode and the cathode, and the electrolyte is an ion exchange membrane. The methanol solution passes through the anode and enters the fuel cell. The fuel cell, through the action of the catalyst, causes the hydrogen contained in the methanol to be cleaved into protons (4) 〇n) and the electrons are changed to another side, and the electrons are formed by an external circuit to form a current to the cathode, and the wire (4) to form a water. (H20). The direct methanol combustion reaction is as follows: Anode: CH3〇H + H2o 4 c〇2 + Rainbow + 6e- 200820483 Cathode _· 3/2 02 + 6H+ + 6e_ — 3 H20 Total reaction: CH3OH + 3/2 02 C〇2 + 2 H2 proton exchange membrane (PEM) is a kind of ion exchange membrane and is a key component of direct methanol fuel cells. According to the requirements of polymer electrolyte fuel cells, ion exchange membranes must have high protons (H+). Conductivity, good mechanical strength 'thermal and chemical stability, moderate water swelling, dimensional stability, and the permeability and diffusivity of the gas or methanol involved in the reaction must be low. 'Perfluorosulfonic acid proton exchange membrane developed by DuPont in 1962. It was used in fuel cells in 1966. The proton exchange membranes used in the preparation of proton exchange membrane fuel cells (PEMFC) have been used in various countries. The all-gas rhein-type proton exchange membrane produced and sold by DuPont is mainly known as Naf1〇n®. However, the price of the membrane is too high, and methanol will permeate from the anode end to the cathode end, resulting in a decrease in battery system performance and fuel loss. Therefore, it is necessary to seek to inhibit the permeability of the domain, but the mass of the sub-particle and the battery performance are not Lower than NafiQn® new film. • At present, the frequency-changing process of the proton exchange surface of the fuel cell is more than a step or electron beam treatment. The formed free radicals are connected to the desired gas molecules, and the formed structure can effectively improve the problem of methanol overflow. There are conditions for the ability to proton conduction (Meier_Haack, L, and M. Muller, 2002, «Use of polyelectrolyte multilayer systems for membrane modification" Macromol. Symp_5 188: 91-103·). Thus, the above-mentioned conventional items There are still many shortcomings, and it is not a good designer, but it has been improved. · The inventors of the present invention have improved and innovated in view of the above shortcomings of the 200820483 derived from the proton exchange membrane used in direct methanol fuel cells. After years of painstaking research, it has finally succeeded in research and development of a meta-cost piece, a proton exchange membrane for a direct methanol fuel cell, and a method for its manufacture. [Invention] The object of the present invention is to provide a direct methanol fuel. The proton exchange membrane of the battery, 'the proton exchange membrane has less methanol permeation than the conventional one, which can effectively block the nail The alcohol molecule passes through to solve the problem of methanol overflow of the proton exchange membrane. The second object of the present invention is to provide a proton exchange membrane for a direct methanol fuel cell, the proton exchange membrane having higher proton conductivity than conventional protons The exchange membrane is better and can improve the H+ proton conductivity. Another object of the present invention is to provide a method for manufacturing a guest exchange membrane for a direct methanol fuel cell, which has simple steps and requires no special equipment. The commercial proton exchange membrane is modified into a low-permeation proton exchange membrane. The proton exchange membrane for a direct methanol fuel cell and the method for producing the same can achieve the above object, and the cation and cation complex itself have Electrostatic attraction, layer-by-layer electrostatic self assembly (LBLESA), a polyelectrolyte multilayer film formed by a high charge density cationic polyelectrolyte and an anionic polyelectrolyte f, adsorbed on a conventional exchange membrane To form a proton exchange enthalpy surface - a polyelectrolytic f multilayer film, this structure refers to the methanol knife passing ' It can make certain water molecules circulate and avoid the phenomenon of methanol overflow. The present invention provides a proton exchange for direct methanol fuel pool, including: 200820483 a proton exchange membrane 1, The proton exchange membrane 1 has a first surface 11 and a second surface 12, wherein the first surface η and the second surface 12 of the proton exchange membrane each have a polyelectrolyte multilayer film 2, 3, and the polyelectrolyte multilayer film 2 The 3 series is composed of at least one or more cationic polyelectrolyte layers 21, 31' interlaced with at least one or more of the anionic polyelectrolyte layers 22, 32. The cationic polyelectrolyte layer is p〇ly (allyamine hydrochloride, FAH), polyallyl-dimethyl ammonium chloride (PDAD) , poly(ethylenimine), PEI), chitosan (Chitosan) and the like. The anionic polyelectrolyte layer is polyacrylic acid (PAA), alginic acid (Alg), poly(styrene sulfonic acid, PSS) or the like. Wherein the number of layers of the cationic polyelectrolyte layer is 1-4 layers. Wherein the number of layers of the anionic polyelectrolyte layer is 1-4 layers. The invention provides a method for manufacturing a proton exchange membrane for a direct sterol fuel cell, comprising the following steps: - Step 1 cleaning a proton exchange membrane; Step 2: immersing the proton exchange membrane in a suitable concentration of cationic polymerization In the electrolyte solution, after being immersed for a certain period of time, the surface of the proton exchange membrane is washed and taken out; Step 3: The proton exchange membrane is immersed in an anionic polyelectrolyte solution of a suitable concentration, and after being immersed for a certain period of time, the proton exchange membrane is washed. After the surface is taken out; Step 4 Repeat steps 2 and 3 several times to finally obtain a proton exchange membrane for direct methanol fuel cell 200820483. In the §~Xu, the proton exchange membrane was cleaned using the aqueous solution of Shame 2 and Qiu 4 to remove organic impurities and inorganic metal ions on the proton exchange membrane, and then the proton exchange membrane was washed with deionized water. Wherein the cation to the solution is polyacrylamide hydrogenated hydrogen (clear amine * hydn dll °ride) ' 'PAH) H propyl dimethyl ammonium chloride (four) y (di dimethyl ' a_nium chbride), PDADMAC), polyether quinone imine (4) coffee (4) (four) (four) ® poly _ (〇 111; 08311) and so on. • The concentration of the sub-polyelectrolyte solution is 0.001-0.2 Μ. In this step 2, the proton exchange membrane is immersed in the cationic polyfluorene for 0.5 to 250 minutes. • In this step 2, the surface of the proton exchange membrane is washed with deionized water. The anionic polyelectrolyte solution is polyacrylic acid (P〇ly (acrylic palladium), alginic acid (Alg), polystyrene (PS), etc. The concentration of the anionic polyelectrolyte solution is 0.001-0.2 μ. " 'In this step 3, the proton exchange membrane is immersed in the anionic polyelectrolyte solution for a period of -0-5-250 minutes. · In this step 3, go The surface of the proton exchange phosphine is washed by ionized water. In this step 4, the steps 2 and 3 are repeated several times to 〇 to 3 times. 200820483 [Embodiment] Example - t-type proton for direct methanol fuel cell In this embodiment, the proton exchange membrane Naf toe m is taken as an example, and the polyelectrolytic f multilayer film is adsorbed on the surface of the lining by a stepwise electrostatic adsorption technique (LBLESA) to produce a proton exchange membrane of a direct methanol fuel cell. Ϊ·membrane cleaning 1. Prepare 3% H2〇2 and 0.5NH2S〇pX solutions in deionized water respectively. 2. Place the proton exchange membrane Nafion-117 in 8 (TC H2〇2 aqueous solution for 6 minutes, To remove organic impurities, then clean the membrane with deionized water. The proton exchange membrane Nafion-117 was treated in an aqueous solution of 80 ° C ΗΑ〇4 for 60 minutes to remove inorganic metal ions, and then the membrane was washed with deionized water and placed in deionized water for use. Adsorption of IL multilayer polyelectrolyte 1 · Prepare a solution of 0.02 mM poly(allyamine hydrochloride, ΡΑΗ) and adjust its pH to 7, then inject it into plastic culture m, then immerse the cleaned proton exchange membrane Nafion-117 into solution. In the middle, let stand for 20 minutes to adsorb polyacrylamide hydrogen bromide (PAH) on the surface of the proton exchange membrane Nafion-117. 2. Clean the deionized water (pH of the polyelectrolyte solution, ie pH 7) Proton exchange membrane

On the surface of Na.fion-117, remove the unadsorbed or weakly adsorbed polyacrylamide hydrogen bromide (PAH). 3. Prepare a solution of 0.02 mM polyacrylic acid (P〇MacryliC acid), PAA) and adjust its pH to 7, then inject it into another plastic culture orphan, and then pass the proton exchange membrane of step 2 Nafion-117 • · - - ----- " _______ Immerse in the solution and let stand for 20 minutes to adsorb polyacrylic acid (PAA) to the proton exchange membrane 11 200820483

Nafion-117 on a polyacrylamide hydrogen bromide (PAH) layer. 4. Wash the surface of the substrate with deionized water (pH of the polyelectrolyte solution, ie, pH 7) to remove the polyacrylic acid (PAA) which is not adsorbed or weakly adsorbed. 5. Repeat steps 1-4 for 0 to 3 times to form a multilayer polyelectrolyte on the proton exchange membrane Nafion-117 in a layer-by-layer (LBL) manner, repeating steps 1-4 once, ie A positively charged polyelectrolyte layer and a negatively charged polyelectrolyte layer are formed on the _ proton exchange membrane, and finally, a proton exchange membrane for a direct methanol fuel cell having 2, 4'6, and 8 polyelectrolyte layers is produced. Example 2 Total reflection infrared light spectrum analysis experiment (atr_ftir) In this embodiment, the surface of the proton exchange membrane produced in Example 1 was qualitatively analyzed by means of total reflection Huo infrared light meter to analyze the quality. Whether the functional groups on the surface of the proton exchange membrane before and after are different. In the total reflection infrared spectroscopy analysis experiment (Attenuated T〇tai Reflectance F () uriei> • TranSfOTmInfrarcd 'ATR-FTM) 'Because the infrared% incident energy partially penetrates the wafer, its wavelength of the fixed frequency is waiting The surface functional groups of the analyte are absorbed at 4 〇〇〇 to 7 〇 (the W-band forms the infrared spectrum of the same absorption peak w ' _ this- nature to identify the surface functional groups of the product, and can change the experimental environment , such as the angle of the incident light or the different ship wafer he called IRE wafer) 'to change the penetration depth of the object to be tested. The experimental procedure is as follows: ‘ 1. Take a 1 cm x 1 cm film and Ge_6〇. (10) The parallelepiped IRE wafer with a depth of about _ (4) is used to contact the object to be tested (4) with a torsion force of 28 〇ζ _ίη. 12 200820483 2. Place it on the ATR fitting with an angle of incidence of 60. The incident energy is above 4300 eV and it is allowed to stand for 20 minutes. After the system is stable, test it again. • 3· Set the spectral resolution to 4 cm_1, wavenumber range 4000~700 cnf1, scan 300 times and get the sample spectrum. The test results are shown in Figure 2. The peaks at 1152 cm-1 and 1219 crrf1 are • . Absorption of S03_ functional group on Nafion-117 membrane, in addition to issOcnf1 to 1485 (wave of ^1 region. Peak is absorption of polyacrylamide hydrogen bromide (PAH) electrolyte NH3+ functional group, 1400 cnf1 to 1300 cm-1 The wave of 肇 region is the absorption of polyacrylic acid (PAA) polyelectrolyte COO-functional group. The untreated proton exchange membrane Nafion-117 is used as the control group (coded by ml〇, as shown in Figure 2 (4)). And the proton exchange membranes each having the 2, 4, 6, and 8 layers of polyelectrolyte layers produced by the first embodiment (each of which is coded by ML2, ML4, ML6, and MLS, each as shown in Fig. 2(b), (c), (4), (5) shown in the comparison; as shown in Figure 2 (8) to (c), the peaks of the NH3+ official energy base and the COCT functional group cannot be clearly observed on the spectrum of ML0, ML2, and ML4, which may be too deep with the irradiation depth. The range of irradiation is related to the proton exchange membrane _ Nafion-117 membrane; when the polyelectrolyte layer is adsorbed to 6 layers (ie ^^, the thickness of the polyelectrolyte layer can reach about 24 〇, as shown in Figure (9) , the peak of the adsorbed polyelectrolyte * cleavage. functional group can be observed in the spectrum; when the polyelectrolyte layer is adsorbed up to 8 layers (ie ML8), MI/Functional Group and (10)-The official silk Linfeng is the most _, as shown in the second paragraph; this result can be engraved and modified to contain polyacrylamide desert hydrogen 7AH) and polyacrylic acid (PAA) substances. The three-contact angle test is used to verify the contact angle of the surface of the proton exchange membrane before and after the fine modification of the Benbe fine towel, in order to analyze the proton exchange of the various sub-exchange membranes obtained by the actual refinement, to verify the proton exchange 13 200820483 The success of the modification of the membrane surface. The experimental steps are as follows: 1. When the object to be tested is placed in the static contact angle meter, the plate is pulled up and the surface of the film is observed after the drop of a drop of pure water. Repeat the operation five times to obtain the average angle. 3·Compared with Μ4 and the modified surface and the uncorrected contact with pure water, the dialysis is hydrophobic and hydrophobic. The result is shown in Figure 3. The contact angle of the proton exchange membrane suspension Gn_m is about 85. After adsorption of the first layer of polyacrylamide hydrogen bromide (pAH), the surface contact angle of the proton exchange membrane does not change much (about 83.) After the layer ride (pAA) layer, the surface of the f-spray is from the surface of the original 4 water (the force 83 is relatively hydrophilic (about 75 5). ), as the number of polyelectrolyte adsorption layers increases, the surface static antenna angle will also change ±τ, and the degree of decrease in the degree of dilation will increase, which is related to the increase of the hydrophilic group contained in the number of the layers of the crucible layer; The result can be indirectly cut, and the surface properties of the substrate change during the dipping process, meaning that the polyelectrolyte does adsorb to the substrate layer by layer, and the data from each sample is measured. It can be observed that the "quasi-deviation value of the static contact angle is less than 5%" indicates that the surface properties of the proton exchange membrane modified in this manner are uniform. Example 4: Transmission electron microscopy (TEM) observation In the 5th addition, the cross-sectional structure of the modified proton exchange membrane was observed by Transmissi〇n Electron Microscopy (TEM), and each layer was estimated. A friend of the electrolyte layer. The steps of greed are as follows: 1) Cut the test object to be tested into an appropriate size, take a small amount of embedding agent in the capsule, and place 14 200820483 on the bottom of the capsule, and then add the appropriate burial age. In the middle of the job, remove the bubbles in the plastic bottle and place it in the 8〇C bin for 8 hours. After the embedding agent is solidified, it can be sliced by the ultra-thin slicer. 2. Slicing with an ultra-thin slicer, firstly repairing the object to be tested with a fine glass. First, the object to be tested is trimmed into a trapezoid of 2 to 5 mm in size, and then sliced with a diamond knife. The thickness of the slice is 50~ 100 nm 〇*: The sample was observed by a penetrating electron microscope (TEM) using a mis-staining of acetic acid. _Results Chan, the sub-grain Gn_117 paste, Figure 4 (4) and Figure 4, respectively, are a simplified cross-section of the proton exchange membrane with 4 layers and 6 layers of polyelectrolyte adsorbed on the surface. After dyeing, the crane can see the surface adsorbed, polyelectrolyte layer 'but S is the structure of the interdigitated structure of the anion and the cation, so the yin and yang polyelectrolyte layered structure can not be effectively obtained. The thickness of the polyelectrolytic f layer is (4) and the left and right, respectively. It can be inferred that the thickness of the single-layer polyelectrolyte layer is about 30 to 50 nm. _ Example 5 pervaporation experiment 'Because the white direct methanol fuel cell system, the anode feed methanol aqueous solution will penetrate the membrane. It penetrates into the cathode and has a percolation overflow phenomenon. The pervaporation experiment was used to investigate whether the aqueous methanol solution was passed through the amount of each proton exchange membrane obtained in Example 1, thereby evaluating whether the modified proton exchange membrane had an effect on the sterol fuel cell effect. Put the protons in the infiltration test device 5 and record the temperature oven % towel, connect the remaining and the money weaving, and then connect the vacuum pump 57 to take the continuous operation to carry out the experiment 'real money office exchange exchange Membrane effective surface 15 200820483 The product is 1.76x10· &, the system towel is transferred below 3 mmHg, and the downstream permeate is condensed with liquid nitrogen after collection and analyzed by gas chromatograph. The experimental steps are as follows. · L cut the film to be phased 4 and measure the film thickness with the thickness of the film. 2. Mount the film 4 to be tested in the penetrant test room 54, connect the pipe and check for leaks, and set Constant temperature oven 55 temperature is 3 0-70t 3. A 3M aqueous methanol solution of known composition is poured from the funnel 51, and the rotary valve 581 is rotated to allow the sterol aqueous solution to enter the storage tank 52, and then the rotary valve 581 is rotated to the position where the aqueous methanol solution can be circulated in the pipeline. · Turn on the south pressure pump 53 and adjust the flow rate to the maximum, let the methanol water sputum circulate upstream. 5. At the same time, open the rotary valve 583, the rotary valve 585, close the rotary valve 584, the rotary valve 586, to the liquid nitrogen condensing device After 56 is collected, the vacuum pump 57 is turned on to evacuate the downstream pipeline. 6. After the system is stabilized, the rotary valve 582 is opened and the timing is started. '7· Fixed time "Replace the liquid nitrogen condensing unit 56 collection bottle, close Turn 583, turn to 58S, open the rotary valve 584, turn valve 586, continue to collect the downstream permeate. 8·Lianbin replace the collection bottle of the liquid nitrogen condensing device 56, repeat the operation in a continuous manner, wait for flux and permeate The composition is unchanged. 9. The weight of the permeate collected by the liquid nitrogen condensing device 56 is weighed and analyzed by gas chromatography (GC). 10. After the experiment is completed, the rotary valve 尧 2 is closed. The storage tank 52 and the methanol aqueous solution in the pipeline are recovered, Repeat the cleaning of the tube with steamed water. Then analyze the collected permeate using a gas chromatograph (GC) HP589〇GC, and analyze the peak area ratio ' by integral 軚16 200820483 to calculate the infiltration. The composition of the experimental conditions with nitrogen when the gas age is arrief gas), the analysis tube (four) capillary record (10) chest cutting, the temperature is set to 120C 'injection port temperature for the boot, TCD detector temperature is 145' t, data processing system The software was processed for chromatographic integration in 浚HW2〇00. The 彡 珍 番 彡 赖 赖 赖 赖 赖 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍 珍As the number of layers increases, the amount of f-liquid riding is followed by Wei, the number of layers of the wire is increased, the thickness of the proton exchange membrane is increased, the enthalpy of resistance is increased, and the amount of alcohol is related to the flux; The sterol concentration of the fresh sub-exchange membrane polyelectron layer number of the map, as can be seen from Figure 7, as the number of poly-layer increases, the methanol concentration at the permeate end decreases, when the proton exchange membrane polyelectrolyte reed number reaches 6 layers The osmotic end has the lowest degree of collaterality and the best effect on the barrier layer.曰Example 6 film swelling test t.. The water content of the 子 燃料 燃料 〜 也 f f f f f f f f f f f f f f f f f f f f f f f f f f f f f f f f f f f Low, too much water, will cause the film to be heavy, the mosquito is poor, the film can be scaled, and the shame is suitable for the (10)f sub-domain film, the actual fine axis, called (four) fine - the obtained I shell film Water content (ie swelling). The experimental steps are as follows: 1. The desired film to be tested is cut by a film cutter that is only 2.5 cm in length. · 2. Place the cut film to be vacuumed 3. Place the dry noodles (4) to 彳~*, _ to remove excess water. From the side-aged child, the Wei side view cover locks the bottle to avoid the weaving. .Asian use bottle 17 200820483 4. 5. Put the bottle in a good mix (peng, peach, machine, (10). (10) hate the warm water tank, take the ridge coffee every time, the shed filter paper rubs the surface water, and Weighing. Using formula 1 to determine the size of the expansion (DS) to be considered, the degree of swelling is defined as follows:

D 100% (Formula 1) wherein, ash D represents the weight (g) when the film to be tested is dried, and ws represents the weight (g) after the film to be tested is swollen. As shown in Figure 8, as the temperature rises, the water content (swelling degree) of the film to be tested rises, which may be that the Γ7 knife chain has better stretchability at the south temperature, which is beneficial to the entry of water molecules. · The electrolysis of the shellfish is the same as that of the shellfish. The higher the water content (swelling degree) at the same temperature, the better the hydrophilicity of the shell surface after changing the 't. The molecules enter the membrane, and the formed 4-clear structure can effectively keep the water molecules inside, so the more the polyelectrolyte layer, the higher the water content. Lu Wei·f sub-material analysis Also, the “EP Impedance” method is the most commonly used method to investigate the proton conductivity of polymer electrolytes. The external supply - AC voltage to the system, and from high frequency scanning to low frequency, for this signal 'system, first g has a corresponding current response, and appears in the form of a sine wave, so it can be analyzed between the high knife electrolysis shell and the interface The resistance can be compared to the conductivity of the proton intersection before and after the modification. · · • The Beacon Conductivity Analysis System is shown in Figure 9. Before the test, the proton exchange membrane to be tested is placed in the distilled water to completely swell, and the operating conditions are 2〇 to (9). c, set the relative humidity at 18 200820483 95% measured its proton conductivity measurement method as follows: 1. Place each proton exchange membrane 87 to be tested in room temperature water, soak the two angel membrane swelling. The test piece 87 of the shellfish to be tested is cut into a 35 cm diameter disc, and placed in a test chamber 84 on the platform of the constant temperature wet box. The test grabs the 84-type device and can receive the environment. Moisture. 3, at both ends of the proton intersection 87 to be tested, the stainless steel electrode pads 841, 842 are tightened, and the pressure applied by the screw (4), the proton interfacial 87 and the single steel electrode plate 841 842 contacts, shaped like a sandwich clip. 4. Connect the working electrode (w〇rking electr〇de) and the auxiliary electrode (c_such as electrode) to the two ends of the electrode and connect the test device to the AC impedance meter (g〇iartr〇n si 1287) a for analysis. . · 5. The AC impedance meter 82 sets a fixed amplitude of 1〇mV and a scanning frequency of 1〇6Hz~〇1Hz. 6. The AC impedance spectrum obtained under different temperatures (2〇-8(TC) and relative humidity 95%) is obtained, and φ is taken to obtain the impedance value of the membrane. The operation of the humidity is consistent with the state of use in the direct methanol fuel cell system. 7. Substitute the membrane impedance data into Equation 2 to obtain proton conductivity.

RbxA (Formula 2) where σ represents conductivity, / represents film thickness ^, Rb represents film resistance value (Ω), and a represents electrode area ((10) 2). 8. The function of the conductivity is a temperature, which can generally be expressed by the Arrlienius equation (Equation 3). 19 200820483 (Formula 3), ", 导电 conductivity 侠 w) ' represents the frequency factor, & In the activation state, moxibustion represents the wave «constant (8.625 x 1G_5 eV/K) and Γ represents the temperature (6). 9· Take the logarithm of the two sides of the formula 3 to get 1ησ = 1ηΑ0 -

kT (Formula 4) 10. If the logarithm of the conductivity is plotted against 1000/τ, a straight line can be obtained, and the slope is substituted into Equation 5 to obtain the activation energy (KJ/mol):

Ea = —(slope .k)x 1〇〇〇

σ ^Α0οχρ[

(Formula 5), the results are as follows *, as can be seen from the actual Guan 6 and this example, the proton exchange membranes to be tested increase the proton conduction as the temperature increases, and the sub-exchange membrane can maintain a good temperature at high temperatures. Moisture content, shame helps the material of the f, and the high temperature can increase the polymer bond and the mass transfer. The proton feed rate increases; the towel has a proton with 6 polyelectrolyte layers. Intersection (9) domain (4) sub-material rate. Under the high temperature _ (that is, in the figure IX minus the standard surface / Τ is 2.8), the proton exchange ray feron conduction ability after the modification is better than the proton exchange before the _ Naf^n7 (to (four) as the inclination) High, the highest Q 2 I can be produced, and the proton exchange membrane Nafl〇n-117 reported by the general literature has a high proton conductivity 〇is/cm. Therefore, the proton exchange membrane provided by the present invention will contribute to direct methanol. The fuel cell is operated at a high temperature, 20 200820483 The protons for the male-can battery provided by the hair ride and its manufacturing method, J-engraved and other conventional techniques are compared with each other (4), and have the following advantages: The manufacturing method of the proton exchange membrane of the battery directly provided by Mao Ming is y (4) The commercial proton exchange membrane can be modified into a low permeability proton exchange membrane by special equipment. ’ 2· _ Touching experiments show that the protons of the direct-a-battery battery provided by this simplification are consistent. 3. It can be seen from the experiment of infiltration* that the proton exchange membrane of the direct and material battery of the present invention has less reduction of the amount of methylation than the manufacturer, and can effectively block the passage of methanol molecules and solve the problem of methanol overflow of the proton exchange membrane. 4. From the proton conductivity analysis, the proton exchange membrane of the proton exchange membrane for a direct methanol fuel cell of the present invention can improve the h+ proton conductivity. The detailed description above is a detailed description of one of the possible embodiments of the present invention, which is intended to limit the scope of the invention, which is equivalent to the spirit of the invention, or more The equivalent embodiment of the proton exchange membrane, the different polyelectrolysis, the f solution, the length of the immersion treatment, and the like, should be included in the patent scope of the present application. In summary, this case is not only innovative in the surface treatment of proton exchange membranes of direct methanol fuel cells, but also enhances the above-mentioned functions by using the articles. It should fully comply with the statutory invention patents of new and progressive nature. __ law to apply, I ask you to approve the invention patent application, in order to invent invention, to the sense of virtue. 21 200820483 [Simple description of the drawings] Figure 1 is a cross-sectional view of the low-permeability proton exchange membrane of the present invention; Figure 2 is a total reflection infrared spectrum analysis experiment (ATR_FTIR) analysis spectrum (a) ML () (control group); (b ML2 (having two layers of proton exchange membrane with electrolyte layer); (6) Μ# (with four layers of shellfish with electrolyzed shells); (d) ML6 (with 6 layers of proton exchange membrane with electrolyte layer); e) ML8 (with 8 layers of proton exchange membrane with electrolyte layer); Figure 2 shows static contact angle analysis of the surface of proton exchange membranes adsorbing different layers of polyelectrolyte layers; Figure 4 (a) shows the layer with polyelectrolyte Transmissive electron microscope (TEM) cross-section of proton exchange membrane (ML4); Figure 4 (b) is a transmission electron microscope (TEM) cross-section of proton exchange membrane (ML6) with 6 polyelectrolyte layers; . Figure 5 is a diagram of the pervaporation experimental setup; Figure 6 is a plot of the permeate end flux versus temperature for a 3M aqueous methanol solution in a pervaporation experiment; ''Figure 7 is a pervaporation experiment where the feed is 3M methanol Diagram of the relationship between methanol concentration and temperature at the permeate end in aqueous solution; Figure 8 is a diagram of the degree of swelling and temperature change of proton exchange membranes with different layers of polyelectrolytes; Figure 9 is a simplified diagram of the experimental device for proton conductivity analysis. Fig. 10 and Fig. 10 are Arrhenius diagrams of proton conductivity and temperature of proton exchange membrane 22 200820483 with different layers of polyelectrolytes at a relative humidity of 95%. [Main component symbol description] 1 Proton exchange membrane 11 First surface 12 Second surface 2 Polyelectrolyte multilayer film 21 Cationic polyelectrolyte layer . 22 anionic polyelectrolyte layer 3 polyelectrolyte multilayer film ^ 31 cationic polyelectrolyte layer 32 anion polyelectrolyte layer 4 film to be tested 5 permeation test device 51 funnel 5 storage plug 53 high pressure pump 54 penetration test room 55 constant temperature oven 56 liquid sorrow Condensation inspection 57 vacuum pump climbing 581 rotary valve 582 rotary valve ' " 583 rotary valve / 584 rotary valve, 585 rotary valve 586 rotary valve '81 computer 82 AC impedance meter.. 83 constant temperature and humidity box 84 test cabin ' 841 Stainless steel electrode plate 23 200820483 842 stainless steel electrode plate 85 temperature controller 86 humidity controller 87 proton exchange membrane to be tested

Claims (1)

200820483 X. Patent application scope: 1. A proton exchange membrane for a direct methanol fuel cell, comprising: a proton exchange membrane having a first surface and a second surface; characterized by the proton exchange membrane Each of the first surface and the second surface has a polyelectrolyte multilayer film composed of at least one or more cationic polyelectrolyte layers, * interlaced with at least one or more anionic polyelectrolyte layers. 2. The proton exchange membrane for a direct methanol fuel cell according to claim 1, wherein the COSCO cationic polyelectrolyte layer is polyaluminium bismuth bromide (PUly (aUyamine hydr〇clll〇ride). , PAH) ^ poly polyfdiallyl-dimethyl ammonium chloride (PDADMAC), poly(ethylenimine), PEI, Chitosan. *3. The proton exchange membrane for a direct methanol fuel cell according to claim 1, wherein the anionic polyelectrolyte layer is polyacrylic acid (p〇ly (acrylic acid), alginic acid (Alginic acid) , Alg), polystyrene (p〇iy (styrene suif〇nic acid) 5 PSS) 〇 4. Proton exchange membrane for direct methanol fuel cells as described in claim i, in The number of layers of the cationic polyelectrolyte layer is 1-4 layers. The proton exchange membrane for a direct methanol fuel cell according to claim 1, wherein the number of layers of the anionic polyelectrolyte layer is 1-4 layers. 6. A method for producing a proton exchange membrane for a direct methanol fuel cell, comprising the steps of: step 1 cleaning a proton exchange membrane; and step 2: immersing the proton exchange membrane in a suitable concentration of a cationic polyelectrolyte solution, After waiting for 25 200820483 for a certain period of time, 'clean the surface of the proton exchange membrane and take it out; Step 3: soak the proton exchange membrane in an appropriate concentration of anionic polyelectrolyte solution, after soaking for a certain time, 'after cleaning the surface of the proton exchange membrane Take out; Step 4 Repeat Step 2 and Step 3 several times to finally obtain a proton exchange membrane for direct methanol fuel cells. 7. The method for producing a proton exchange membrane for a direct sterol fuel cell according to claim 6, wherein in the step 1, the proton exchange membrane is washed with a solution of sputum 2 and h2so4, respectively, to remove the proton exchange membrane. The proton exchange membrane organic impurities and inorganic metal ions, and then the proton exchange membrane is washed with deionized water. 8. The method for producing a proton exchange membrane for a direct methanol fuel cell according to claim 6, wherein the % ion polyelectrolyte solution is polyallysamine (PAH). ·), dially dimethyl dimethyl chloride (p〇iy (dially 1-dimethyl ammonium chloride), PDADMAC), polyether oxime imine (p〇ly (ethyienimine), PEI), chitosan ( Chitosan) ♦ 9. The method for cultivating a proton exchange membrane for a direct methanol fuel cell according to claim 6, wherein the cationic polyelectrolyte solution has a concentration of 0.001 to 0.2 Μ. The method for producing a proton exchange membrane for a direct methanol fuel cell according to the item 6, wherein in the step 2, the proton exchange membrane is immersed in the cationic polyelectrolyte solution for 0.5 to 250 minutes. The method for producing a proton exchange membrane for a direct methanol fuel cell according to the sixth aspect of the patent, wherein in the step 2, the surface of the proton exchange membrane is washed with deionized water. 26 200820483 12 · as claimed in claim 6 The method for producing a proton exchange membrane for a direct methanol fuel cell, wherein the anion electrolyte solution is polyacrylic acid (P〇ly (acfylic acJd), PAA), bath (Alginic acid, Alg), polybenz Sty · · sty sty · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · The concentration is 〇〇〇1_〇2Μ. > 14. The method for producing a proton exchange membrane for a direct methanol fuel cell according to claim 6, wherein in the step 3, the proton exchange membrane The method for producing a proton exchange membrane for a direct methanol fuel cell, as described in claim 6, wherein the step of immersing in the anionic polyelectrolyte solution is 0.5-250 minutes. The surface of the proton exchange membrane is cleaned by deionized water. The method for producing a proton exchange membrane for a direct methanol fuel cell according to claim 6, wherein in step 4, steps 2 and 3 are repeated. Several times To 3 times. 27