Title of Invention	"A DIRECT OXIDATION FUEL CELL"
Abstract	A direct oxidation fuel cell having an anode, a cathode, a proton conducting membrane disposed between said anode and said cathode, means for stonhg or supplying an organic fuel to the anode, and means for supplying oxygen to the cathode, wherein said organic fuel is selected from the group consisting of dimethyl oxalate, ethylene glycol, its oxalic, glyoxalic, and formic esters, glyoxylic acid and its methyl esters, glyoxylic aldehyde, and poly(ethylene oxalate).

Title of Invention

"A DIRECT OXIDATION FUEL CELL"

Abstract

A direct oxidation fuel cell having an anode, a cathode, a proton conducting membrane disposed between said anode and said cathode, means for stonhg or supplying an organic fuel to the anode, and means for supplying oxygen to the cathode, wherein said organic fuel is selected from the group consisting of dimethyl oxalate, ethylene glycol, its oxalic, glyoxalic, and formic esters, glyoxylic acid and its methyl esters, glyoxylic aldehyde, and poly(ethylene oxalate).

Full Text	1 NOVEL FUELS FIELD OF THE INVENTION The invention relates to fuel cells and to organic fuels for use in fuel cells. BACKGROUND OF THE INVENTION Hydrocarbons and aliphatic alcohols are very difficult to electro-oxidize completely (J. Wang, S. Wasmus, and R. F. Savinell, J. Electrochem. Soc. 142, 4218 (1995)),the main products of aliphatic alcohols oxidation being aldehydes or ketones, CO2 and acids or esters. Even at 190°C, in a polymer-electrolyte membrane (PEM) Fuel Cell, the oxidation of ethanol is incomplete, the main oxidation product (over 60%) is ethanal while CO2 is less than 40% of the oxidation products. A compound which does not electro-oxidize in 80% or more cannot be considered an efficient tuel. To the best knowleicige of the inventors there has never been a report on the complete electro-oxidation of a compound having a C-C bond, except for oxalic acid (V. S. Bagotzky and Y. B. Vasilyev, Electrochemica Acta 9,869 (1964)). There are several publications that teach fuels for use in fuel cells. Among them US 5,599,638 mentions tbe gse of methanol, formaldehyde, formic acid, dimethoxymethane, trimethoxymethane, and trioxane. In a screening of about 150 organic compounds as potential fuels for fuel cells, which was carried out by NASA (NASA report No.~SP 120 (1967), chapter 15, pp. 225 ff.) only methanol was checked for being an effective ftieh The other organic molecules were tested in acidic, neutral or basic solutions for their half cell potential, and the voltage of the electrode was measured at different currents and temperatures and the maximum power per cm2 was calculated, assuming a theoretical oxygen electrode. All di£ molecules that were screened showed some maximum power in the range 1 to 250 mW/cm2. Howsver, this parameter does not teach whether a compound is a good candidate as a fuel. For 2 example, methanol, which is considered a good organic fuel and ethanol, which can hardly be considered a fuel showed similar values of maximum power in acidic medium (13 and 15 mW/cm2 respectively). It was reported in SP-120 (chapter 16, pp. 262 ff.) that ethylene glycol and urea performed poorly (in 30% KOH fuel cell). Some other molecules mentioned in this NASA report are glycerol, glyoxal aldehyde and glyoxylic acid. SUMMARY OF THE INVENTION The present invention provides organic fuels for fuel cells. The organic fuels according to the present invention are selected from the group consisting of dimethyl oxalate (DMO), ethylene glycol (EG), its oxalic, glyoxalic, and formic esters, glyoxylic acid and its methyl esters, glyoxylic aldehyde, and poly(ethylene oxalate), the latter being a polyester of oxalic acid and ethilene glycol. The organic fuels of the invention undergo clean and efficient oxidation in non-alkaline fuel cells, especially in acidic fuel cells. Preferable fuels according to the present invention are dimethyl oxalate, ethylene glycol, its formic acid ester, ethylene oxalate and polyethylene oxalate). Most preferable fuels according to the present invention are etfcf&eae glycol and dimethyl oxalate. Preferable fuels of the invention are those that goes over 80% conversion to CO2, and leave only negligible amounts of nonvolatile side products when used as fuels in a fuel cell. Non-limiting examples of fuel cells that may work satisfactorily with the fuels of the invention are liquid feed fuel cells, gas feed fuel cells, high temperature fuel cells, solid oxide fuel cells, molten carbonate fuel cells, and fuel cells that use proton exchange or proton conducting membranss. Preferably, fuel cells that use proton exchange or proion conducting membranes, or solid oxide fuel cells. 3 The invention also provides for mixtures of the fuels of the inventions, as well as mixtures of the fuels of the invention with known organic fuels, such as methanol, for use as fuels in fuel cells. Some of the fuels of the invention may also be useful with alkaline fuel cells, especially in elevated temperatures. However, when alkaline electrolyte is used, there may be a need to replace it from time to time, due to incomplete electro-oxidation of the fuels in basic environment and the accumulation of carbonates or other organic salts due to this incomplete electro-oxidation. When fuel cells operate with the fuels of the invention they exhibit crossover current density which is lower than that the same fuel cells exhibit when operating with methanol, which is currently the most commonly used fuel in such cells. The low crossover current results in high efficiency. Without being bound to theory, it may be assumed that the low crossover currents are attributed to the large molecular size of the fuels of the invention, in comparison with that of methanol. The large molecular size is correlated with a small diffusion coefficient, which leads to small crossover current density. Furthermore, the fuels of the invention have higher boiling points man methanol, thus transporting through the-proton conducting membrane mainly in their liquid phase. Naturally, the diffusion coefficient in liquid phase is smaller than in the gas phase. The solid fuels of the invention, such as DMO and poly(ethylene oxalate), may be advantageous over liquid fuels like methanol for several reasons such as their easier-haridling and their lower solubility in water. Thus, they maintain low concentration tuch helps in keeping the crossover current low. Furthermore, it is possible to store sailitlifcd solutions thereof, for example, in the anode chamber of the fuel cell, together wiUlCteaiderable amount of solid fuel, which dissolves when the ceil is in oper&tiOQ-"t$\|\|jji&gl is consumed, while the non-dissolved solid fuel serves as a fuei reservoir. 4 In accordance with another of its aspects the invention provides a direct oxidation fuel cell having an anode, a cathode, a proton conducting membrane disposed between said anode and said cathode, means for supplying an organic fuel to the anode and means for supplying oxygen to the cathode, wherein said organic fuel is selected from the group consisting of dimethyl oxalate (DMO), ethylene glycol (EG), its oxalic, glyoxalic, and formic esters, glyoxylic acid and its methyl esters, glyoxylic aldehyde, and poly(ethylene oxalate). Preferable cells according to tins aspect of the invention are those wherein the fuels are selected from the group consisting of dimethyl oxalate, ethylene glycol, its oxalic and formic acid esters, and poly(ethylene oxalate). Most preferable fuel cells according to this aspect of the present invention are those wherein the fuel is selected from the group consisting of ethylene glycol and dimethyl oxalate. According to one embodiment, the fuel cell according to this aspect of the present invention is further characterized in that the CO2 produced during the operation thereof is released through a thin hydrophobic porous matrix placed in the anode compartment or in the fuel tank, thus allowing the release of the gas without losing solution. According to another of its embodiments the present invention provides for a fuel cell, which is specifically adapted for workingrwiA thfejRiels of the invention. Such a fuel cell is characterized by having a cathode comprising ,in addition to oxygen reduction catalyst, a.fuel oxidation catalyst, non-limiting examples thereof are Pt-Ru, Pt-Sn, Pt-Ru-Sn, Pt-Ag-Ru, Pt-Os catalyst, or combination of these catalysts. The fuel oxidation catalyst at the cathode improves oxidation of the fuel that crossed over the membrane and prevents it from deactivating the oxygen reduction catalyst of the cathode, which typically is a Pt or Pt alloy catalyst The practical ratio between the reduction catalyst to the oxidation catalyst is between 1% to 50%, preferably 5% to 2C% (w/w) or between 0.01 to 5mg, preferably between 0.05 to 0.2mg oxidation catalyst per cm2 of the oxygen electrode. 5 The invention further provides, according to another of its aspects, a method for evaluating the concentration of the new fuels in at a predetermined temperature, the method comprising the following steps: (a) preparing calibration curves of crossover current vs. fuel concentration at said predetermined temperature in a fuel cell; (b) measuring the crossover current at said predetermined temperature in said fuel cell; and (c) evaluating the fuel concentration from the current measured in step (b) and the calibration curve prepared in step (a). This method is based on the inventors finding that crossover current in fuel cells of the invention is directly proportional to the fuel concentration. For instance, the crossover current density of 1M EG at 80°C was found to be about twice that of 0.5M EG at the same temperature (41 and 19mA/cm2, respectively) and the crossover current density of 0.25M DMO at 60°C was found to be about 2.5 times that of 0.1M DMO at fhe same temperature (2.5 and 0.9mA/cm2, respectively). This finding is valid under conditions ensuring that the measured current is independent of the voltage at which it is measured. The method of the invention may be applied to measure the fuel concentration of a fuel solution in a working fuel cell. This may be carried out by measuring the crossover current in the operating fuel cell. Alternatively, an auxiliary small fuel cell for carrying out the measurement may be provided. This alternative allows for the measurement in accordance with the invention without having to operate the whole fuel cell in the voltage required for the measurement. The auxiliary fuel cell may be physically separated from the fuel cell, build in it, attached to it or attached to the fuel tank. The present invention also provides for a hybrid power source comprising at least one fuel cell according to the present invention a DC tc DC converter, and a rechargeable battery. Direct methanol fuel cell (DMFC) and liquid feed fuel cells (LFFC) are \ low power sources. However, devices like cellular telephones, computers and 6 small electric vehicles need high power for short times. For these and for similar applications it is possible to combine a fuel cell according to the invention with a small high power rechargeable battery, which supplies the high power when required. Such a combination is advantageous over current art hybrid power source, inter alia thanks to the small crossover current. Today DC to DC converters can start working from 0.7V. As a it is possible to combine as few as two or three fuel cells (in a series combination) through a DC to DC converter to a battery. If the crossover current density is small enough, say 15mA/cm2 or less, preferably 5mA/cm2 or less, such a hybrid power source need not be fueled very often. Therefore, this hybrid power source is preferably with a fuel cell of low crossover current density such as the fuel cell of the invention. The fuel cell charges the battery and supplies the low power demand while the high power battery supplies the heavy loads. This small number of required fuel cells enables the use of a flat and thin fuel cell system. The present invention provides such hybrid power sources that are fueled with the fuels of the present invention. Fueling such hybrid power sources with a solid fuel of the present invention will be most advantageous. For example, to power a cellular phone it is possible to use a hybrid power source built of two thin fuel cells, connected in a series combination and fueled by liquid fuels of the invention such as EG or by a solid fuel of the invention, such as DMO, a DC to DC converter and a small high power lithium ion cell. BRIEF DESCRIPTION OF THE DRAWINGS In order to better understand the invention and to see how it may work in practice, several embodiments of the invention will now be described in detail, with reference to the accompanying drawings, in which: Fig. 1 is a graph showing polarization curves of some dieis according io the present invention and some currant art fuels; and 7 Fig. 2 is a schematic illustration of a solid feed organic fuel cell in accordance with the invention. DETAILED DESCRIPTION OF SOME EMBODIMENTS Example 1: Obtaining polarization curves for several fuels A fuel cell was manufactured with the use of pure metal catalysts, instead of carbon supported catalysts. A cathodic catalyst ink was prepared by the following process: A nano powder Pt (Pt black, purchased from "Johnson Matthey"), TeflonTM emulsion and NafionTM 5% solution were combined in the following weight proportions: 60%Pt, 25% Teflon emulsion and 15% Nafion. First the Pt powder and the Teflon emulsion were mixed by sonication for 15 minutes. After two sonication periods, the ink obtained was placed on a magnetic stirrer for at least one night. An anodic catalyst ink was prepared by the following process: A PfcSn nano powder (Pt:Ru black 50% purchased from "Johnson Matthey") and PVDF were mixed in the following weight proportions: 91% catalyst powder and 9% PVDF. Propylene carbonate was added in an amount equal to 30-70% of the catalyst volume, then cyclopentanone was added and the ink obtained was stirred for at least one night. Preparation of the electrodes: the cathode catalyst ink was applied on teflonated TorayTM carbon fiber paper, to form 4 mg Pt/cm2. The ink (in the form of a paste) was spread in layers, allowing each layer to dry for about one hour, before the next layer was applied. This operation was repeated mail the desired amount of catalyst was obtained. In the same way, the anode catalyst ink was applied on unteflonated TorayTM carbon fiber paper, until 5-10 mg catalyst/cm2 was obtained. Both electrodes were washed with 3M sulfuric acid and then with water. 8 The cathode and the anode were placed on both sides of the PCM, with a thickness of 100-300 um, parallel to each other and were hot pressed under a pressure of 10-70 Kg/cm2 , at a temperature of 85-130° Fig. 1 illustrates polarization curves for this kind of fuel cell under the following conditions: a solution of the fuel and 3M H2SO4 was circulated through the anode at a rate of 9ml/min. Oxygen was circulated past the cathode at a pressure of 0.25 atm. over the atmospheric pressure. The cell temperature was 65°C. The PCM was 300 micron thick, consisting of (V/V) 16% nanosize powder of SiO2, 24% PVDF and 60% pore volume, of 1.5 nm typical diameter. The cell demonstrated over 100 hours of stable operation at 0.4V. The fuels tested have been: methanol (1M), oxalic acid (0.1M with memanol 1M, Oxalic acid 0.1M, dimethyl oxalate 0.1M, ethylene glycol 0.5M, and giycerol 0.5M. (Of these, glycerol oxalic acid and methanol are not n accordance of the present invention.) As shown in the graph, under these conditions DMO and EG had the best performance. However, one should keep in mind tfa& none of the conditions in this experiment was optimized, so that other concentrations and/or other catalysts could have resulted in qualitatively different observations. Fuel utilization was determined by performing electrochemical titrations of 50 ml of feel soterion at caasaaa voltage until the current dropped to 3 mA. It is estimated that at this current only a few percents of the fuel left not oxidized. The utilization was calculated by comparing, the experimental capacity with the theoretical value. A further correction was made by extrapolation of the titration curves to zero current. This correction increases the utilization values by 3 to 6% (Table 1). Fuel utilization at 0.2V was found to be 95% for DMO, 94% for EG and only 85% for methanol (see Table 1). At the more practical voltage of 0.4V, fuel utilization was found to be 89% for EG, 67% for DMO ar.c 31 Vi for methane!. As the fuel does crossover to the cathode side, these high fuel utilization values soggestthere is dose to 100% fuel electro-oxidation. 9 Measurements of fuel crossover were carried out at several temperatures by feeding nitrogen instead of oxygen into; the cathode compartment (at ambient pressure) and. feeding organic fuel-acid solution into the anode compartment. Cell voltage was reversed; hydrogen was evolved at the fuel electrode while fuel that crossed over to the cathode side was oxidized. The current that flows at IV was found to be the limiting current for oxidation of all fuels. Table 2 summarizes the fuel crossover test results. The crossover current density depends on fuel permeability, temperature, concentration and on the total number of electrons involved in the oxidation. The crossover current density for 1M methanol (at 80°C) is double that of 1M EG and that of 0.25M DMO. However, when the number of electrons is taken into account and the fuel flux in terms of mol's' cm"2 (at 80°C and under diffusion-controlled conditions) is normalized to 1M fuel, it can be seen that the permeability (flux) of EG is one-third that of methanol while that of DMO is almost as large as that of methanol. Table 1: Utilization comparison of different fuels. Number of electrons Theoretical . Clanacitv Utilization AtO.4V £%1 Utilizat AtO.2\ [%] ion r Corr. Exp. Corr Oxalic acid 2 0.43 91 Methanol 6 5.03 79 81 82 85 Ethylene glycol 10 432 83 89 89 94 Dimethyl oxalate 14 3.18 64 61 93 95 An average of at least two tests; 10 Exp. - experimental values; Corr. - corrected values, see text. Table 2: Crossover of different fuels. 1. Fuel Crossover test: ¦. . ¦ /". V; i Temp. [°C] Cone. Crossover current Density [A/cm2] Fuel flux [mol s 1#cnf2] lxlO"8 Dimethyl oxalate 60 0.10 0.009 6.7 60 0.25 0.025 7.4 80 , 0.25 0.038 11 Ethylene glycol 80 0.5 0.019 3.9 80 1.0 0.041 42 Methanol 80 1.0 0.076 13 Normalized to 1M Example 2: Application of fuels according to the invention to a Nation(tm) based fuel cell A fuel cell housing was fabricated from synthetic graphite plates purchased from Globetech Inc., in which a flow field was engraved. The anode was formed using a platinum-ruthenium ink that was spread on a carbon fiber sheet commercially available from Toray(tm) paper. The catalyst layer consists of 15% Teflon (DuPont), 15% Nafion(tm) and 70% Pt-Ru nanopowder (Pt:Ru black 50% purchased from "Johnson Matthey"). Anode loading was 5mg/cm2. The cathode used was a commercially available ELAT E-TEK(tm) consisting of 4mg Pt/cm and 0.6 mg nafion/cxn . The anode and cathode were hot pressed to a 117 Nafion membrane, available from DuPont, to form die membrane electrode assembly (MEA) as described in Example 1. 11 After cooling the ME A was placed between the graphite flow field plates, a polypropylene sealing was inserted and the cell was assembled. During operation, an aqueous solution of a fuel selected from oxalic acid, dimethyl oxalate, ethylene glycol, glycerol, in the concentration range of 0.1-0.5 M was circulated past the anode (with the use of a peristaltic Masterflex L/S Cole-Panher Instrument Co. pump) at different flow rates from 4 to 15ml/min. Oxygen was fed into the cathode chamber directly or through a water bubbler at an ambient pressure and at a rate of 7io 40 ml/min. The cells were run at 60°C. The polarization curves were found to be similar to those of Figure 1. Example 3. Solid feed organic fuel cell Fig. 2 illustrates a solid feed organic fuel cell having a plastic case 501, an anode 509, a cathode 511 and a solid polymer electrolyte membrane 510. The membrane 510 was a PCM of the kind described in WO99/44245, consisting of 12% SiO2 28% PVDF and 60% voids introduced). The anode, cathode and MEA were prepared as in Example 1. The solid organic fuel is filled through the fuel hole 502 and sealed with a cork 503. The fuel is dissolved in the tank and is absorbed through a hastalloy C-276 (Cabot) net 507 at a porous carbon cloth 508. Carbon dioxide formed in the anode compartment is vented through an exhaust nozzle 504. Since liquid fuel may leek through the exhaust nozzle, the nozzle is covered with a thin hydrophobic porous layer 506. The hydrophobic layer is permeable to the gas only while the fuel solution remains in the tank. The cathode is open to air through a second hastalloy net 513. In order to prevent the fuel leaking from the cathode side, the MEA is sealed with a gasket 512. The second hastalloy net 513 is used also as a cover to the whole assembly. 200mg DM0 were dissolved into the fuel tank, which contained 1M H2SO4 solution. The fuel cell delivered 30mA at 0.35V. The crossover current density was 2 siA/cm2 at room temperature. 12 WE CLAIM: 1. A direct oxidation fuel cell having an anode, a cathode, a proton conducting membrane disposed between said anode and said cathode; means for storing or supplying an organic fuel to the anode, and means tot supplying oxygen to the cathode, wherein said organic fuel is selected from the group consisting of dimethyl oxalate, ethylene glycol, its oxalic, glyoxalic, and formic esters, glyoxylic acid and its methyl esters, glyoxylic aldehyde, and poly(ethylene oxalate). 2. A direct oxidation fuel ceil according to claim 9 wherein said fuels are selected from the group consisting of dimethyl oxaiate, ethylene glycol, its oxalic and formic acid esters, ethylene oxalate, polyethylene oxaiate), and mixtures thereof. 3. A direct oxidation fuel cell according to claim 10 wherein the fuel is selected from the group consisting of dimethyl oxalate, ethylene glycol, its formic acid ester, ethylene oxalate, po!y(ethyiene oxaiate), and mixtures thereof. 4. A direct oxidation fuel cell according to claim 11 wherein the fuel is selected from the group consisting of dimethyl oxalate, ethylene glycol, and mixtures thereof. 5. A direct oxidation fuel cell according to any one of claims 9 to 12, wherein said fuel ceil is liquid feed. 6. A direct oxidation fuel cell according to claim 12 wherein the fuel is selected from the group consisting of poiy(ethy!ene oxaiate), dimethyl oxalate, and mixtures thereof. 7. A direct oxidation fuel cell according to any one of claims 9 or 14, having a thin hydrophobic porous matrix placed in the anode compartment or in the fuel tank to release therethrough CO2 produced during the operation of the fuel cell. 8. A direct oxidation fuel cell according to any one of claims 9 to 15 wherein said anode comprises Pt: Ru catalyst. 1. 13 9. A method for converting in a fuel cell more than 80% of a fuel to CO2, the method comprising the steps of: (i) providing a fuel ceil having an anode, a cathode, a proton conducting membrane disposed between said anode and said cathode, means for storing or supplying an organic, fuel to the anode, and means for supplying oxygen to the cathode; (ii) fuel said fuel cell; and (iii) operating said fuel cell; characterized in that said fuel is selected from dimethyl oxalate, ethyiene glycol, its oxalic, glyoxalic, and formic esters, glyoxylic acid and its methyl esters, glyoxylic, and polyethylene oxalate). 10. A method according to claim 9 wherein said anode comprises a Pt.Ru catalyst. 11. A method according to claim 9 and 10 wherein said fuei cell is operated in step (tit) at a temperature of 60°C and above. 12. A method according to any one of claims 9 and 11, wherein the cathode comprises oxygen reduction catalyst and a fuei oxidation catalyst. 13. A method according to claim 12 wherein said fuei oxidation catalyst is selected from the group consisting of Pt-Ru, Pt-Sn, Pt-Ru-Sn, Pt-Ag-Ru, Pt-Os catalysts, and any combination thereof. 14. A method according to any one claims 12 and 13 wherein the ratio between the fuel oxidation catalyst to the oxygen reduction catalyst is between 1% to 50%, (w/w). 15. A method according to claim 14 wherein said ratio is between 5% to 20%, (w/w). 16. A method according to any one one of claims 9 to 15 wherein said organic compounds are selected from the group consisting of dimethyl oxaiate, ethyiene glycol, its formic acid ester, ethyiene oxalate and polyethylene oxalate), and mixtures thereof. 10. 14 17. A method according fo any one of claims 9 to 15 wherein said organic compounds are selected from the group consisting of ethylene gtycol dimethyl oxalafe and mixtures thereof. 18. A method according the any one of claims 9 to 15 wherein said organic compounds are selected from the group consisting of dimethyl oxalate, poly(e(hylene oxalate) and mixtures thereof. 19. A method according to any one of claims 9 to 15 wherein said organic compounds are mixed with known fuel. 20. A method according to claim 19 wherein said known fuel is methanol. 21. A direct oxidation fuel cell, having a cathode comprising an oxygen reduction catalyst and a fuel oxidation catalyst. 22. A direct oxidation fuel cell according to claim 21 wherein said fuel oxidation catalyst is selected from the group consisting of Pt-Ru, Pt-Sn, Pt-Ru- Sn, Pt-Ag-Ru, Pt-Os catalysts, and any combination thereof. 23. A direct oxidation fuel cell according to claim 22 wherein the ratio between the fuel oxidation catalyst to the oxygen reduction catalyst is between 1% to 50% (w/w). 24. A direct oxidation fuel cell according to claim 23 wherein said ratio is between 5% to 20%, (w/w). 25. A direct oxidation fuel cell according to any one of claims 21 to 24, wherein said fuei is a mixture as defined in claim 19 or 20. 17. 15 26. A method for evaluating the concentration of fuels in a solution, at a predetermined temperature, the fuels being dimethyl oxaiate, ethylene gtycoi, its oxalic, glyoxalic, and formic esters, glyoxylic acid and its methyl esters, giyoxylic aldehyde, or po(y(ethylene oxaiate), comprising the following steps: a) preparing calibration curves of crossover current vs. fuet concentration at said predetermined temperature in a given fuel cell; b) measuring the crossover current at said predetermined temperature in said given fuei cell; and evaluating the fuei concentration from the crossover current measured in step b) and the calibration curves prepared in step a). ?7. A hybrid power source comprising at least one fuel cell according to any one of claims 1 to 8 or 21 to 25, a DC to DC converter, and a rechargeable battery. 28. A hybrid power source comprising at least one fuei ceil according to claim 6, a DC to DC converter, and a rechargeable battery. A direct oxidation fuel cell having an anode, a cathode, a proton conducting membrane disposed between said anode and said cathode, means for stonhg or supplying an organic fuel to the anode, and means for supplying oxygen to the cathode, wherein said organic fuel is selected from the group consisting of dimethyl oxalate, ethylene glycol, its oxalic, glyoxalic, and formic esters, glyoxylic acid and its methyl esters, glyoxylic aldehyde, and poly(ethylene oxalate).

Full Text

1
NOVEL FUELS

FIELD OF THE INVENTION
The invention relates to fuel cells and to organic fuels for use in fuel cells.
BACKGROUND OF THE INVENTION
Hydrocarbons and aliphatic alcohols are very difficult to electro-oxidize
completely (J. Wang, S. Wasmus, and R. F. Savinell, J. Electrochem. Soc. 142,
4218 (1995)),the main products of aliphatic alcohols oxidation being aldehydes
or ketones, CO2 and acids or esters. Even at 190°C, in a polymer-electrolyte
membrane (PEM) Fuel Cell, the oxidation of ethanol is incomplete, the main
oxidation product (over 60%) is ethanal while CO2 is less than 40% of the
oxidation products. A compound which does not electro-oxidize in 80% or more
cannot be considered an efficient tuel. To the best knowleicige of the inventors
there has never been a report on the complete electro-oxidation of a compound
having a C-C bond, except for oxalic acid (V. S. Bagotzky and Y. B. Vasilyev,
Electrochemica Acta 9,869 (1964)). There are several publications that teach
fuels for use in fuel cells. Among them US 5,599,638 mentions tbe gse of
methanol, formaldehyde, formic acid, dimethoxymethane, trimethoxymethane,
and trioxane. In a screening of about 150 organic compounds as potential fuels
for fuel cells, which was carried out by NASA (NASA report No.~SP 120 (1967),
chapter 15, pp. 225 ff.) only methanol was checked for being an effective ftieh
The other organic molecules were tested in acidic, neutral or basic solutions for
their half cell potential, and the voltage of the electrode was measured at different
currents and temperatures and the maximum power per cm2 was calculated,
assuming a theoretical oxygen electrode. All di£ molecules that were screened
showed some maximum power in the range 1 to 250 mW/cm2. Howsver, this
parameter does not teach whether a compound is a good candidate as a fuel. For

2
example, methanol, which is considered a good organic fuel and ethanol, which can hardly be considered a fuel showed similar values of maximum power in acidic medium (13 and 15 mW/cm2 respectively). It was reported in SP-120 (chapter 16, pp. 262 ff.) that ethylene glycol and urea performed poorly (in 30% KOH fuel cell). Some other molecules mentioned in this NASA report are glycerol, glyoxal aldehyde and glyoxylic acid.
SUMMARY OF THE INVENTION
The present invention provides organic fuels for fuel cells. The organic fuels according to the present invention are selected from the group consisting of dimethyl oxalate (DMO), ethylene glycol (EG), its oxalic, glyoxalic, and formic esters, glyoxylic acid and its methyl esters, glyoxylic aldehyde, and poly(ethylene oxalate), the latter being a polyester of oxalic acid and ethilene glycol. The organic fuels of the invention undergo clean and efficient oxidation in non-alkaline fuel cells, especially in acidic fuel cells. Preferable fuels according to the present invention are dimethyl oxalate, ethylene glycol, its formic acid ester, ethylene oxalate and polyethylene oxalate). Most preferable fuels according to the present invention are etfcf&eae glycol and dimethyl oxalate. Preferable fuels of the invention are those that goes over 80% conversion to CO2, and leave only negligible amounts of nonvolatile side products when used as fuels in a fuel cell.
Non-limiting examples of fuel cells that may work satisfactorily with the fuels of the invention are liquid feed fuel cells, gas feed fuel cells, high temperature fuel cells, solid oxide fuel cells, molten carbonate fuel cells, and fuel cells that use proton exchange or proton conducting membranss. Preferably, fuel cells that use proton exchange or proion conducting membranes, or solid oxide fuel cells.

3
The invention also provides for mixtures of the fuels of the inventions, as well as mixtures of the fuels of the invention with known organic fuels, such as methanol, for use as fuels in fuel cells.
Some of the fuels of the invention may also be useful with alkaline fuel cells, especially in elevated temperatures. However, when alkaline electrolyte is used, there may be a need to replace it from time to time, due to incomplete electro-oxidation of the fuels in basic environment and the accumulation of carbonates or other organic salts due to this incomplete electro-oxidation.
When fuel cells operate with the fuels of the invention they exhibit crossover current density which is lower than that the same fuel cells exhibit when operating with methanol, which is currently the most commonly used fuel in such cells. The low crossover current results in high efficiency. Without being bound to theory, it may be assumed that the low crossover currents are attributed to the large molecular size of the fuels of the invention, in comparison with that of methanol. The large molecular size is correlated with a small diffusion coefficient, which leads to small crossover current density.
Furthermore, the fuels of the invention have higher boiling points man methanol, thus transporting through the-proton conducting membrane mainly in their liquid phase. Naturally, the diffusion coefficient in liquid phase is smaller than in the gas phase.
The solid fuels of the invention, such as DMO and poly(ethylene oxalate), may be advantageous over liquid fuels like methanol for several reasons such as their easier-haridling and their lower solubility in water. Thus, they maintain low concentration tuch helps in keeping the crossover current low. Furthermore, it is possible to store sailitlifcd solutions thereof, for example, in the anode chamber of the fuel cell, together wiUlCteaiderable amount of solid fuel, which dissolves when the ceil is in oper&tiOQ-"t$||jji&gl is consumed, while the non-dissolved solid fuel serves as a fuei reservoir.

4
In accordance with another of its aspects the invention provides a direct oxidation fuel cell having an anode, a cathode, a proton conducting membrane disposed between said anode and said cathode, means for supplying an organic fuel to the anode and means for supplying oxygen to the cathode, wherein said organic fuel is selected from the group consisting of dimethyl oxalate (DMO), ethylene glycol (EG), its oxalic, glyoxalic, and formic esters, glyoxylic acid and its methyl esters, glyoxylic aldehyde, and poly(ethylene oxalate). Preferable cells according to tins aspect of the invention are those wherein the fuels are selected from the group consisting of dimethyl oxalate, ethylene glycol, its oxalic and formic acid esters, and poly(ethylene oxalate). Most preferable fuel cells according to this aspect of the present invention are those wherein the fuel is selected from the group consisting of ethylene glycol and dimethyl oxalate.
According to one embodiment, the fuel cell according to this aspect of the present invention is further characterized in that the CO2 produced during the operation thereof is released through a thin hydrophobic porous matrix placed in the anode compartment or in the fuel tank, thus allowing the release of the gas without losing solution.
According to another of its embodiments the present invention provides for a fuel cell, which is specifically adapted for workingrwiA thfejRiels of the invention. Such a fuel cell is characterized by having a cathode comprising ,in addition to oxygen reduction catalyst, a.fuel oxidation catalyst, non-limiting examples thereof are Pt-Ru, Pt-Sn, Pt-Ru-Sn, Pt-Ag-Ru, Pt-Os catalyst, or combination of these catalysts. The fuel oxidation catalyst at the cathode improves oxidation of the fuel that crossed over the membrane and prevents it from deactivating the oxygen reduction catalyst of the cathode, which typically is a Pt or Pt alloy catalyst The practical ratio between the reduction catalyst to the oxidation catalyst is between 1% to 50%, preferably 5% to 2C% (w/w) or between 0.01 to 5mg, preferably between 0.05 to 0.2mg oxidation catalyst per cm2 of the oxygen electrode.

5
The invention further provides, according to another of its aspects, a method for evaluating the concentration of the new fuels in at a predetermined temperature, the method comprising the following steps:
(a) preparing calibration curves of crossover current vs. fuel concentration
at said predetermined temperature in a fuel cell;
(b) measuring the crossover current at said predetermined temperature in
said fuel cell; and
(c) evaluating the fuel concentration from the current measured in step (b)
and the calibration curve prepared in step (a).
This method is based on the inventors finding that crossover current in fuel cells of the invention is directly proportional to the fuel concentration. For instance, the crossover current density of 1M EG at 80°C was found to be about twice that of 0.5M EG at the same temperature (41 and 19mA/cm2, respectively) and the crossover current density of 0.25M DMO at 60°C was found to be about 2.5 times that of 0.1M DMO at fhe same temperature (2.5 and 0.9mA/cm2, respectively). This finding is valid under conditions ensuring that the measured current is independent of the voltage at which it is measured.
The method of the invention may be applied to measure the fuel concentration of a fuel solution in a working fuel cell. This may be carried out by measuring the crossover current in the operating fuel cell. Alternatively, an auxiliary small fuel cell for carrying out the measurement may be provided. This alternative allows for the measurement in accordance with the invention without having to operate the whole fuel cell in the voltage required for the measurement. The auxiliary fuel cell may be physically separated from the fuel cell, build in it, attached to it or attached to the fuel tank.
The present invention also provides for a hybrid power source comprising at least one fuel cell according to the present invention a DC tc DC converter, and a rechargeable battery.
Direct methanol fuel cell (DMFC) and liquid feed fuel cells (LFFC) are \ low power sources. However, devices like cellular telephones, computers and

6
small electric vehicles need high power for short times. For these and for similar applications it is possible to combine a fuel cell according to the invention with a small high power rechargeable battery, which supplies the high power when required. Such a combination is advantageous over current art hybrid power source, inter alia thanks to the small crossover current. Today DC to DC converters can start working from 0.7V. As a it is possible to combine as few as two or three fuel cells (in a series combination) through a DC to DC converter to a battery. If the crossover current density is small enough, say 15mA/cm2 or less, preferably 5mA/cm2 or less, such a hybrid power source need not be fueled very often. Therefore, this hybrid power source is preferably with a fuel cell of low crossover current density such as the fuel cell of the invention. The fuel cell charges the battery and supplies the low power demand while the high power battery supplies the heavy loads. This small number of required fuel cells enables the use of a flat and thin fuel cell system.
The present invention provides such hybrid power sources that are fueled with the fuels of the present invention. Fueling such hybrid power sources with a solid fuel of the present invention will be most advantageous.
For example, to power a cellular phone it is possible to use a hybrid power source built of two thin fuel cells, connected in a series combination and fueled by liquid fuels of the invention such as EG or by a solid fuel of the invention, such as DMO, a DC to DC converter and a small high power lithium ion cell.
BRIEF DESCRIPTION OF THE DRAWINGS
In order to better understand the invention and to see how it may work in practice, several embodiments of the invention will now be described in detail, with reference to the accompanying drawings, in which:
Fig. 1 is a graph showing polarization curves of some dieis according io the present invention and some currant art fuels; and

7
Fig. 2 is a schematic illustration of a solid feed organic fuel cell in accordance with the invention.
DETAILED DESCRIPTION OF SOME EMBODIMENTS Example 1: Obtaining polarization curves for several fuels
A fuel cell was manufactured with the use of pure metal catalysts, instead of carbon supported catalysts. A cathodic catalyst ink was prepared by the following process:
A nano powder Pt (Pt black, purchased from "Johnson Matthey"), TeflonTM emulsion and NafionTM 5% solution were combined in the following weight proportions: 60%Pt, 25% Teflon emulsion and 15% Nafion. First the Pt powder and the Teflon emulsion were mixed by sonication for 15 minutes. After two sonication periods, the ink obtained was placed on a magnetic stirrer for at least one night.
An anodic catalyst ink was prepared by the following process: A PfcSn nano powder (Pt:Ru black 50% purchased from "Johnson Matthey") and PVDF were mixed in the following weight proportions: 91% catalyst powder and 9% PVDF. Propylene carbonate was added in an amount equal to 30-70% of the catalyst volume, then cyclopentanone was added and the ink obtained was stirred for at least one night.
Preparation of the electrodes: the cathode catalyst ink was applied on teflonated TorayTM carbon fiber paper, to form 4 mg Pt/cm2. The ink (in the form of a paste) was spread in layers, allowing each layer to dry for about one hour, before the next layer was applied. This operation was repeated mail the desired amount of catalyst was obtained. In the same way, the anode catalyst ink was applied on unteflonated TorayTM carbon fiber paper, until 5-10 mg catalyst/cm2 was obtained. Both electrodes were washed with 3M sulfuric acid and then with water.

8
The cathode and the anode were placed on both sides of the PCM, with a thickness of 100-300 um, parallel to each other and were hot pressed under a pressure of 10-70 Kg/cm2 , at a temperature of 85-130° Fig. 1 illustrates polarization curves for this kind of fuel cell under the following conditions: a solution of the fuel and 3M H2SO4 was circulated through the anode at a rate of 9ml/min. Oxygen was circulated past the cathode at a pressure of 0.25 atm. over the atmospheric pressure. The cell temperature was 65°C. The PCM was 300 micron thick, consisting of (V/V) 16% nanosize powder of SiO2, 24% PVDF and 60% pore volume, of 1.5 nm typical diameter. The cell demonstrated over 100 hours of stable operation at 0.4V. The fuels tested have been: methanol (1M), oxalic acid (0.1M with memanol 1M, Oxalic acid 0.1M, dimethyl oxalate 0.1M, ethylene glycol 0.5M, and giycerol 0.5M. (Of these, glycerol oxalic acid and methanol are not n accordance of the present invention.) As shown in the graph, under these conditions DMO and EG had the best performance. However, one should keep in mind tfa& none of the conditions in this experiment was optimized, so that other concentrations and/or other catalysts could have resulted in qualitatively different observations.
Fuel utilization was determined by performing electrochemical titrations of 50 ml of feel soterion at caasaaa voltage until the current dropped to 3 mA. It is estimated that at this current only a few percents of the fuel left not oxidized. The utilization was calculated by comparing, the experimental capacity with the theoretical value. A further correction was made by extrapolation of the titration curves to zero current. This correction increases the utilization values by 3 to 6% (Table 1).
Fuel utilization at 0.2V was found to be 95% for DMO, 94% for EG and only 85% for methanol (see Table 1). At the more practical voltage of 0.4V, fuel utilization was found to be 89% for EG, 67% for DMO ar.c 31 Vi for methane!.
As the fuel does crossover to the cathode side, these high fuel utilization values soggestthere is dose to 100% fuel electro-oxidation.

9
Measurements of fuel crossover were carried out at several temperatures by feeding nitrogen instead of oxygen into; the cathode compartment (at ambient pressure) and. feeding organic fuel-acid solution into the anode compartment. Cell voltage was reversed; hydrogen was evolved at the fuel electrode while fuel that crossed over to the cathode side was oxidized. The current that flows at IV was found to be the limiting current for oxidation of all fuels.
Table 2 summarizes the fuel crossover test results. The crossover current density depends on fuel permeability, temperature, concentration and on the total number of electrons involved in the oxidation. The crossover current density for 1M methanol (at 80°C) is double that of 1M EG and that of 0.25M DMO. However, when the number of electrons is taken into account and the fuel flux in terms of mol's' cm"2 (at 80°C and under diffusion-controlled conditions) is normalized to 1M fuel, it can be seen that the permeability (flux) of EG is one-third that of methanol while that of DMO is almost as large as that of methanol.
Table 1: Utilization comparison of different fuels.

Number of electrons
Theoretical . Clanacitv
Utilization AtO.4V £%1
Utilizat AtO.2\ [%]
ion
r

Corr.
Exp.
Corr
Oxalic acid
2
0.43

91

Methanol
6
5.03
79
81
82
85
Ethylene glycol
10
432
83
89
89
94
Dimethyl oxalate
14
3.18
64
61
93
95
An average of at least two tests;

10
Exp. - experimental values; Corr. - corrected values, see text. Table 2: Crossover of different fuels.

1. Fuel

Crossover test:
¦. . ¦ /". V; i

Temp. [°C]
Cone.
Crossover current Density [A/cm2]
Fuel flux [mol s 1#cnf2] lxlO"8
Dimethyl oxalate
60
0.10
0.009
6.7

60
0.25
0.025
7.4

80 ,
0.25
0.038
11
Ethylene glycol
80
0.5
0.019
3.9

80
1.0
0.041
42
Methanol
80
1.0
0.076
13
Normalized to 1M
Example 2: Application of fuels according to the invention to a Nation(tm) based fuel cell
A fuel cell housing was fabricated from synthetic graphite plates purchased from Globetech Inc., in which a flow field was engraved.
The anode was formed using a platinum-ruthenium ink that was spread on a carbon fiber sheet commercially available from Toray(tm) paper. The catalyst layer consists of 15% Teflon (DuPont), 15% Nafion(tm) and 70% Pt-Ru nanopowder (Pt:Ru black 50% purchased from "Johnson Matthey"). Anode loading was 5mg/cm2. The cathode used was a commercially available ELAT E-TEK(tm) consisting of 4mg Pt/cm and 0.6 mg nafion/cxn . The anode and cathode were hot pressed to a 117 Nafion membrane, available from DuPont, to form die membrane electrode assembly (MEA) as described in Example 1.

11
After cooling the ME A was placed between the graphite flow field plates, a polypropylene sealing was inserted and the cell was assembled.
During operation, an aqueous solution of a fuel selected from oxalic acid, dimethyl oxalate, ethylene glycol, glycerol, in the concentration range of 0.1-0.5 M was circulated past the anode (with the use of a peristaltic Masterflex L/S
Cole-Panher Instrument Co. pump) at different flow rates from 4 to 15ml/min.
Oxygen was fed into the cathode chamber directly or through a water bubbler at an ambient pressure and at a rate of 7io 40 ml/min. The cells were run at 60°C. The polarization curves were found to be similar to those of Figure 1.
Example 3. Solid feed organic fuel cell
Fig. 2 illustrates a solid feed organic fuel cell having a plastic case 501, an
anode 509, a cathode 511 and a solid polymer electrolyte membrane 510. The
membrane 510 was a PCM of the kind described in WO99/44245, consisting of
12% SiO2 28% PVDF and 60% voids introduced). The anode, cathode and MEA were prepared as in Example 1. The
solid organic fuel is filled through the fuel hole 502 and sealed with a cork 503.
The fuel is dissolved in the tank and is absorbed through a hastalloy C-276
(Cabot) net 507 at a porous carbon cloth 508. Carbon dioxide formed in the
anode compartment is vented through an exhaust nozzle 504. Since liquid fuel
may leek through the exhaust nozzle, the nozzle is covered with a thin
hydrophobic porous layer 506. The hydrophobic layer is permeable to the gas
only while the fuel solution remains in the tank. The cathode is open to air
through a second hastalloy net 513. In order to prevent the fuel leaking from the
cathode side, the MEA is sealed with a gasket 512. The second hastalloy net 513
is used also as a cover to the whole assembly. 200mg DM0 were dissolved into
the fuel tank, which contained 1M H2SO4 solution. The fuel cell delivered 30mA
at 0.35V. The crossover current density was 2 siA/cm2 at room temperature.

12 WE CLAIM:
1. A direct oxidation fuel cell having an anode, a cathode, a proton
conducting membrane disposed between said anode and said cathode; means
for storing or supplying an organic fuel to the anode, and means tot supplying
oxygen to the cathode, wherein said organic fuel is selected from the group
consisting of dimethyl oxalate, ethylene glycol, its oxalic, glyoxalic, and formic
esters, glyoxylic acid and its methyl esters, glyoxylic aldehyde, and poly(ethylene
oxalate).
2. A direct oxidation fuel ceil according to claim 9 wherein said fuels are
selected from the group consisting of dimethyl oxaiate, ethylene glycol, its oxalic
and formic acid esters, ethylene oxalate, polyethylene oxaiate), and mixtures
thereof.
3. A direct oxidation fuel cell according to claim 10 wherein the fuel is
selected from the group consisting of dimethyl oxalate, ethylene glycol, its formic
acid ester, ethylene oxalate, po!y(ethyiene oxaiate), and mixtures thereof.
4. A direct oxidation fuel cell according to claim 11 wherein the fuel is
selected from the group consisting of dimethyl oxalate, ethylene glycol, and
mixtures thereof.
5. A direct oxidation fuel cell according to any one of claims 9 to 12, wherein
said fuel ceil is liquid feed.
6. A direct oxidation fuel cell according to claim 12 wherein the fuel is
selected from the group consisting of poiy(ethy!ene oxaiate), dimethyl oxalate,
and mixtures thereof.
7. A direct oxidation fuel cell according to any one of claims 9 or 14, having a
thin hydrophobic porous matrix placed in the anode compartment or in the fuel
tank to release therethrough CO2 produced during the operation of the fuel cell.
8. A direct oxidation fuel cell according to any one of claims 9 to 15 wherein
said anode comprises Pt: Ru catalyst.
1.
13
9. A method for converting in a fuel cell more than 80% of a fuel to CO2, the
method comprising the steps of:
(i) providing a fuel ceil having an anode, a cathode, a proton conducting membrane disposed between said anode and said cathode, means for storing or supplying an organic, fuel to the anode, and means for supplying oxygen to the cathode; (ii) fuel said fuel cell; and (iii) operating said fuel cell;
characterized in that said fuel is selected from dimethyl oxalate, ethyiene glycol, its oxalic, glyoxalic, and formic esters, glyoxylic acid and its methyl esters, glyoxylic, and polyethylene oxalate).
10. A method according to claim 9 wherein said anode comprises a Pt.Ru
catalyst.
11. A method according to claim 9 and 10 wherein said fuei cell is operated in
step (tit) at a temperature of 60°C and above.
12. A method according to any one of claims 9 and 11, wherein the cathode
comprises oxygen reduction catalyst and a fuei oxidation catalyst.
13. A method according to claim 12 wherein said fuei oxidation catalyst is
selected from the group consisting of Pt-Ru, Pt-Sn, Pt-Ru-Sn, Pt-Ag-Ru, Pt-Os
catalysts, and any combination thereof.
14. A method according to any one claims 12 and 13 wherein the ratio
between the fuel oxidation catalyst to the oxygen reduction catalyst is between
1% to 50%, (w/w).
15. A method according to claim 14 wherein said ratio is between 5% to 20%,
(w/w).
16. A method according to any one one of claims 9 to 15 wherein said organic
compounds are selected from the group consisting of dimethyl oxaiate, ethyiene
glycol, its formic acid ester, ethyiene oxalate and polyethylene oxalate), and
mixtures thereof.
10.
14
17. A method according fo any one of claims 9 to 15 wherein said organic
compounds are selected from the group consisting of ethylene gtycol dimethyl
oxalafe and mixtures thereof.
18. A method according the any one of claims 9 to 15 wherein said organic
compounds are selected from the group consisting of dimethyl oxalate,
poly(e(hylene oxalate) and mixtures thereof.
19. A method according to any one of claims 9 to 15 wherein said organic
compounds are mixed with known fuel.
20. A method according to claim 19 wherein said known fuel is methanol.
21. A direct oxidation fuel cell, having a cathode comprising an oxygen
reduction catalyst and a fuel oxidation catalyst.
22. A direct oxidation fuel cell according to claim 21 wherein said fuel
oxidation catalyst is selected from the group consisting of Pt-Ru, Pt-Sn, Pt-Ru-
Sn, Pt-Ag-Ru, Pt-Os catalysts, and any combination thereof.
23. A direct oxidation fuel cell according to claim 22 wherein the ratio between
the fuel oxidation catalyst to the oxygen reduction catalyst is between 1% to 50%
(w/w).
24. A direct oxidation fuel cell according to claim 23 wherein said ratio is
between 5% to 20%, (w/w).
25. A direct oxidation fuel cell according to any one of claims 21 to 24,
wherein said fuei is a mixture as defined in claim 19 or 20.
17.
15
26. A method for evaluating the concentration of fuels in a solution, at a predetermined temperature, the fuels being dimethyl oxaiate, ethylene gtycoi, its oxalic, glyoxalic, and formic esters, glyoxylic acid and its methyl esters, giyoxylic aldehyde, or po(y(ethylene oxaiate), comprising the following steps:
a) preparing calibration curves of crossover current vs. fuet concentration
at said predetermined temperature in a given fuel cell;
b) measuring the crossover current at said predetermined temperature in
said given fuei cell; and
evaluating the fuei concentration from the crossover current measured in step b)
and the calibration curves prepared in step a).
?7. A hybrid power source comprising at least one fuel cell according to any
one of claims 1 to 8 or 21 to 25, a DC to DC converter, and a rechargeable
battery.
28. A hybrid power source comprising at least one fuei ceil according to claim
6, a DC to DC converter, and a rechargeable battery.
A direct oxidation fuel cell having an anode, a cathode, a proton conducting membrane disposed between said anode and said cathode, means for stonhg or supplying an organic fuel to the anode, and means for supplying oxygen to the cathode, wherein said organic fuel is selected from the group consisting of dimethyl oxalate, ethylene glycol, its oxalic, glyoxalic, and formic esters, glyoxylic acid and its methyl esters, glyoxylic aldehyde, and poly(ethylene oxalate).

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Patent Number

210022

Indian Patent Application Number

IN/PCT/2002/00913/KOL

PG Journal Number

37/2007

Publication Date

14-Sep-2007

Grant Date

13-Sep-2007

Date of Filing

12-Jul-2002

Name of Patentee

TEL-AVIV UNIVERSITY FUTURE DEVELOPMENT L.P.

Applicant Address

C/O TAU FUTURE TECHNOLOGY MANAGEMENT LTD. C/O. TEL-AVIV UNIVERSITY ECONOMIC CORPORATION LTD P.O. BOX 39040, TEL-AVIV 69978, ISRAEL

Inventors:

#	Inventor's Name	Inventor's Address
1	MELMAN AVI	KDOSHEI KAHIR STREET 30,58362 HOLON,ISRAEL
2	AHARON ADI	HAHAGANA STREET,57,46325 HERZLIYA,ISRAEL
3	PELED EMANUEL	HANOTEA STREET 25,40500 EVEN YEHUDA,ISRAEL
4	DUVDEVANI TAIR	CARMELI STREET 19,52233 RAMAT GAN,ISRAEL

PCT International Classification Number

H 01 M 8/10

PCT International Application Number

PCT/IL01/00054

PCT International Filing date

2001-01-18

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	09/484,267	2000-01-18	U.S.A.