IL126830A

IL126830A - Ion conductive matrixes and their uses

Info

Publication number: IL126830A
Application number: IL12683098A
Authority: IL
Inventors: Melman Avi; Peled Emanuel; Duvdevani Tair
Original assignee: Univ Ramot
Priority date: 1998-10-30
Filing date: 1998-10-30
Publication date: 2001-05-20
Also published as: IL126830A0

Abstract

An ion conducting matrix comprising: (i) 5% to 60% by volume of an inorganic powder having a good aqueous electrolyte absorption capacity; (ii) 5% to 50% by volume of a polymeric binder that is chemically compatible with an aqueous electrolyte; and (iii) 10 to 90% by volume of an aqueous electrolyte, wherein the inorganic powder comprises essentially sub-micron particles and said aqueous electrolyte consists of an aqueous soluble compound selected from a salt, a base or mixtures thereof.

Description

Ion conductive matrixes and their uses Ramot University Authority for Applied wnwwm tn*n Research & Industrial Development Ltd. ^1»V The inventors: Emanuel Peled Tair Duvdevani Avi Melman C.113708 ION CONDUCTIVE MATRIXES AND THEIR USES FIELD OF THE INVENTION The present invention relates to ionic conductive matrixes, membranes and electrodes, their manufacture and use. In particular, the present invention is concerned with membranes comprising composite polymeric films and composite polymers.

BACKGROUND OF THE INVENTION Ionic conducting membranes (to be referred to hereinafter as "/CM") are to be found in many electrochemical cells, among which: fuel cells, electrolyzers, electrochromic cells, batteries, electrochemical sensors and others. In some cases, polymer electrolyte is used such as Nafion. However, Nafion based fuel cells suffer from two major disadvantages. The first is that Nafion is a very expensive material and the second, its characteristic to dry out during the fuel cell operation due to water dragging by the protons conducted.

US 5,456,600 teaches the use of a polymeric membrane for making an lithium-ion rechargeable battery cell. The membrane disclosed is a combination of a poly(vinylidene fluoride) copolymer matrix and a compatible organic solvent plasticizer which maintains a homogenous composition in the form of a flexible, self-supporting film.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a novel, low cost and highly conductive ion conducting matrix.

It is another object of the present invention to provide novel, low cost and highly conductive ion conducting membranes and electrodes.

Another object of the present invention is to provide electrochemical cells comprising the matrixes of the invention.

It is yet a further object of the invention to provide methods for preparing such membranes and electrodes.

Still, it is the object of the present invention to provide uses for the ion conducting membranes and electrodes of the invention.

Other objects of the invention will become apparent as the description of the invention proceeds.

The present invention provides" by the first of its aspects an ion conducting matrix comprising: (i) 5% to 60% by volume of a inorganic powder having a good - aqueous electrolyte absorption capacity;- - - (ii) 5% to 50% by volume of a polymeric binder that is chemically compatible with an aqueous electrolyte; and (iii) 10 to 90% by volume of an aqueous electrolyte, wherein the inorganic powder comprises essentially sub-micron particles, preferably from about 5 to about 150 ran in size.

In accordance with a preferred embodiment of the present invention, the inorganic powder is characterized in that it has a surface area of at least 10 m /g, and possesses a good absorption capability for the aqueous electrolyte.

According to another aspect of the invention, there is a provided a membrane being a film made of the matrix of the invention.

According to a further aspect of the invention, there is provided a composite electrode comprising 10 to 70% by volume of the matrix of the invention and the balance is made essentially by an electrode material, which is a material known in the art per se as a suitable material in the manufacturing of electrodes, eg. carbon, graphite, air, oxygen, H2, methanol electrodes, Zn, Cd, Ni, Pb, Fe, Cu or their alloys, metal oxide electrodes, e.g. RuO2, WOx, MnO2, NiOOH, AgO, Ag2O and the like.

In the case that the matrix of the invention is used as an ion conducting matrix in a composite electrode, the inorganic powder may be electronically conductive.

Preferably, the inorganic powder of the matrix of the present invention is a member selected from the group consisting of SiO2, ZrO2, B2O3, TiO2, Al203 and the like.

The polymeric binder used in the matrix of the present invention is a material which is chemically compatible with an aqueous electrolyte used, i.e. non-soluble in that electrolyte, and is "a member selected from the group consisiting of: polyvinilyden fluoride (PVDF), PVDF-hexafluoropropylene (PVDHFP), poly(tetrafluoroethylene) (PTFE), poly(methylmethacrylate) (PMMA), polysulfone amide, poly(acrylamide), polyvinyl- chloride (PVC), acrylonitrile, polyvinyl fluoride and any combination thereof.

The aqueous electrolyte of the present invention consists of an aqueous soluble compound selected from a salt, a base or mixtures thereof. Examples of aqueous soluble salts are alkali metal salts, alkali earth metal salts, P NX where R is hydrogen or an organic radical and X is an anion derived from an inorganic acid, NH4C1, ZnCl2 and any combinations thereof.

Examples of aqueous soluble bases for use in the present invention are R4NOH where R is hydrogen or an organic radical, alkali or alkali earth base compounds and any combinations thereof.

The ICM of the present invention has the general appearance of a plastic film, having good mechanical properties. It can typically be bent to about 180° with no substantial fractures occurring, and it can be prepared in thickness being in the range of from about 10 to about 1000 microns or more. Due to its stability and good ionic conductivity, it can be used at a large temperature range of from sub-zero to about 150°C.

According to a preferred embodiment of the invention, where the matrix is in the preparation of a membrane, the inorganic powder comprised in the matrix is a very fine, electronically non-conductive powder having a particle size of preferably less than 150 ran. According to this embodiment, the ICM pores in which the aqueous electrolyte is absorbed are very small, and their characteristic dimension is essentially smaller than 50 nm.

The absorption capacity or the retention capability of the membrane for the aqueous electrolyte used depends on several parameters, among which are the composition and the type of the inorganic powder, the polymeric binder and the type of the dissolved electrolyte. The combination of these parameters should be optimized in order to tailor the product for each application. While carrying out such optimization, consideration should be given to the fact that the highest the content of inorganic powder is; the inferior \_^·-.·.·...- · - .^- ^^-.the mechanical properties become. Increasing the inorganic powder content of the matrix increases its electrolyte retention characteristic, but at the same time, decreases its mechanical strength. On the other hand, increasing the polymeric binder in the matrix increases the strength of the latter, but decreases the wettability of the matrix thus turning it to a less conductive one.

According to yet another embodiment of the invention, an improvement of the matrix wettability and consequently the electrolyte retention, is achieved by adding to the membrane multi valance metal salts such as Al, Zr, B, Ti and the like.

According to another embodiment of the invention, the improvement of the matrix wettability and consequently the electrolyte retention, is achieved by pre-treating the inorganic powder with an acid or a base prior to the preparation of the membrane.

Still by another embodiment of the present invention, there is provided a membrane as described above that is mechanically reinforced. The reinforcement can be done by any way known per se in the art, e.g., including in the membrane an electronically non-conductive screen, felt, fibers or any other reinforcing element as known in the art.

The ionic conducting membranes of the invention may be prepared by any one of several methods, which are also encompassed by the present invention, among which are casting and extrusion. The method for casting an ICM according to the present invention comprises the following steps: (i) preparing a mixture comprising an inorganic powder, a polymeric binder that is chemically compatible with an aqueous electrolyte, at least one solvent characterized in having a high boiling point of above 100°C and at least one low boiling point- solvent, having- a boiling point lower than that of the high boiling point solvent(s), in which the polymeric binder is soluble or form a gel at the casting temperature; (ii) casting a film out of the mixture; (iii) allowing the low boiling point solvent to evaporate from the mixture, thus forming a solid film; (iv) washing the solid film and replacing the high boiling point solvent with the desired aqueous electrolyte solution to be included in the membrane.

According to a preferred embodiment of the invention, the mixture is prepared in a paste-like gel or gel form and is introduced into a mold to obtain the required film form. The evaporation of the low boiling solvent as described in step (iii) should not necessarily be completed prior to proceeding to step (iv), and it may suffice that a solid film which can be further processed, is obtained. The film is then washed, preferably first with water and then with the electrolyte to be absorbed in the matrix, forming the required membrane. This step is carried preferably at a temperature of less than 150°C. The use of water or the electrolyte may be done by repeating immersions of the film therein so as to displace the water or the high boiling solvent, as applicable. Preferably, the last immersion is conducted at an elevated temperature so as to evaporate the solvent and allow the aqueous electrolyte solution to replace it in the membrane formed. When using a water non-soluble high boiling point solvent, the process involves washing the solid film with another solvent that is water soluble, followed by washing the solid film with water.

When casting a composite electrode which comprises the matrix of the present invention, the mixture prepared in step (i) of the above-described method, comprises a further powder of the suitable electrode material. The ~ remaining steps of the process are carried mutatis mutandis as described in the method for casting an ICM.

According to a further embodiment of the invention, the high boiling point solvent is a water soluble solvent, and is preferably a member selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), dimethyl phthalate, diethyl phthalate, dibutyl phthalate and the like of any combinations thereof.

According to another embodiment of the invention, the low boiling point solvent is a member selected from the group consisting of tetrahydrofuran (THF), DME, cyclopentanon, acetone, N-methyl pyrrolidon (NMP), dimethylacetainide (DMAC), methylethylketone (MEK), dimethylformamide and the like, or any combination thereof.

The method for extruding an ICM according to the invention comprises the following steps: (i) preparing a mixture comprising an inorganic powder, a polymeric binder that is chemically compatible with an aqueous electrolyte and at least one solvent characterized in having a boiling point of above 90°C in which the polymeric binder is at least partially soluble or form a gel at extrusion temperature; (ii) heating the mixture to its softening temperature; (iii) forming a film out of the mixture by hot extruding the softened mixture; (iv) cooling the film thus formed; (v) washing the solid film and replacing the solvent with the desired aqueous electrolyte solution to be included in the membrane.

When extruding a composite electrode which comprises the matrix of the present invention, the mixture prepared in step (i) of the above-described method comprises a further powder of +he suitable electrode material. The remaining steps of the process are carried mutatis mutandis as described in me method of extruding an ICM.

According to a preferred embodiment of the invention, the solvent suitable for the extrusion method is a water soluble solvent being a member selected from the group consisting of propylene carbonate, diethyl carbonate, dimethyl carbonate, butryoalactone, methyl isoamyl ketone, cyclohexanone, dialkyl phthalate, glycerol triacetate and the like or any combinations thereof.

The washing of the film described in step (v) is preferably done first with water and then with the aqueous electrolyte to be dissolved into the matrix, to form the required membrane. Water or the electrolyte is applied by repeatedly immersing the film therein so as to displace the water or the solvent, as applicable.

Another aspect of the invention concerns possible uses of the matrixes of the invention. One such use is the manufacture of electrochemical cells that are substantially free from mobile liquid electrolyte solution. Electrochemical cells may comprise an ICM sandwiched by two electrodes. Such electrodes are carbon or graphite, Zn, Fe, Cd, Ni, Cu, Al and their alloys; electrodes or metal oxide electrodes, e.g. of RuO2s WOx, MnO2, NiOOH, AgO, Ag2O and the like. This type of a cell may be manufactured by using a hot press technique. In this process, the two electrodes and the ICM therebetween are pressed together at the softening temperature of the binder, with or without a solvent, typically at a temperature in the range of from about 60° to 150° and under 20 to 1000 Kg/cm for about 1 to 10 minutes, obtaining a single structural cell unit with improved mechanical strength and performance.

According to a preferred embodiment of the invention, a Zn cell may also be manufactured by hot pressing together a cathode, an anode and an ICM therebetween. In this process the anode consists of a ceramic powder binder such as PVDF and Zn in the form of a fine powder; the cathode may also consist of PVDF, ceramic powder, a metal oxide such as MnO2 and a small amount of carbon or graphite. In case that a Zn air cell is assembled, the cathode is a commercial air electrode made of platinum or another catalyst supported on carbon or graphite particles, paper or felt.

Cells such as Zn/air or Zn/oxygen cells consisist of: 1) a composite Zn electrode made typically of about 30% v/v the ICM matrix and 70% of Zn in the form of a fine powder. The preferred Zn powder consists of up to 0.1% (w/w) Hg, Sn, In, Bi, Pb or mixture thereof for corrosion prevention; 2) an ICM; 3) an oxygen or air electrode. The air or oxygen electrode consists of a catalyst selected from Pt, Pd, W, Mn, Cu, Ag, Ni or their mixture or their oxides supported by carbon or graphite powder. The amount of the catalyst is from about 5% to about 50% w/w relative to the carbon or graphite powder. One side of the air or oxygen electrode is hydrophilic and the other side is hydrophobic. Commercially available air or oxygen electrodes can be used or they can be made with the ICM matrix where the hydrophobic side contains more than 25% v/v polymer, preferably Teflon and no ceramic powder.

For example, according to the present invention, nickel-cadmium and nickel-iron batteries consist of a cathode made of NiOOH powder and the ICM matrix, while the anode is made of either cadmium based powder and ICM matrix or iron based powder and the ICM matrix.

In all cases, the polymer binder must be chemically compatible with both the electrolyte and the electrode materials. For alkali solutions, binders such as Teflon (PTFE), polycarbonate, PVC, polypropylene and rubber are preferred.

. The "following examples are not to be" construed as limiting the invention as described herein.

EXAMPLES Example 1 A membrane film was manufactured by mixing 0.170 g of powdered Kynar PVDF 2801-00 and 0.147 gr of high surface area, amorphous fumes particle size 400 m2/g silicon (IV) oxide, 99.8% Alfa Aesar by A. Johnson Matthey Company, with a 20 ml. of cyclopentanon and 0.48 ml of propylene carbonate (PC). The viscous mixture obtained, was poured onto a Teflon plate and was allowed to dry at room temperature for 24 hours. Thereafter, a flexible, strong, transparent film was obtained.

The film was washed by using double distilled water in order to remove the PC. Following the washing, the film became less transparent, but possessed higher mechanical strength. In the Tables presented in the proceeding Examples, the following terms are used to describe mechanical properties: Bad - denotes a membrane which can easily be torn by hand, Good - denotes a membrane that is not easily torn by hand, Very Good.denotes a membrane for which rupture extensive force is required.

In the same manner, other samples were made in different compositions as can be seen in Table 1.

TABLE 1: ICM composition and mechanical properties Samples number 9 and 11 exhibited the best wetting and capillary properties/This sample after water wash could be bent 180%) without causing any damage to the film. Moreover, an acid wet film was heated at 110° C for several hours, and its structure remained intact and its capillary properties did not change. The pore size distribution of this ICM was measured using Quantachrome NOVA 2200 Surface Area Analyzer. It was found that a significant volume (above 15%) of the nanosize pores had a diameter smaller than 3 nm.

The thickness of the ICMs described in Table 1 were in the range of 0.05 to 1mm.

Example 2 A membrane film was manufactured by mixing 0.850 gr of powdered Kynar PVDF 2801-00 with 1.363 gr of high surface area Titania, in 25 ml cyclopentanon with 2.4 ml of PC. The viscous mixture was poured on a Teflon plate as described in Example 1 and was allowed to dry at room temperature for 24 hours. Thereafter, a flexible, opaque white film with very good mechanical strength was obtained.

The film was washed with double distilled water, similarly to the treatment in Example 1. In the same manner, other samples were prepared while different compositions were used. The results obtained are given in Table 2.

TABLE 2: ICM composition and mechanical properties Sample No. TiO2vol.% PVDF vol.% Porosity ICM - 7 / vol. % mechanical properties 1 2.5 22.5 75% Very Good 2 7.5 17.5 75% Very Good 3 10.0 15.0 75% Very Good Example 3 A membrane film was manufactured by mixing 0.85 gr of Kynar PVDF 2801-00 with 1.270 gr of micropolish 0.05 micron gamma Alumina manufactured by Buehler, in 20 ml of acetone with 2.4 ml of PC. The viscous mixture was poured on a Teflon plate as described in the preceding examples. A flexible, opaque white film having very good mechanical strength was thus obtained.

Example 4 A film prepared according to the description given for sample No. 9 in Example 1 was immersed in several aqueous solutions of KOH. The results are summarized in Table 3.

TABLE 3 - Characterization of KOH Based ICM Example 5 A double layer capacitor having two Ti foils as current collectors, was assembled. Two 4.91cm composite carbon electrodes, were mounted on both sides of an ICM prepared in accordance with the disclosure of Example 4. Each carbon electrode was comprised of two layers: the first layer was a 0.3 mm thick porous layer, made of 15% SiO2, 5% oxidized Shawinigm Blac, 50% oxidized Graphite, 10% Teflon and 10% Graphite fibers, pressed under 100 kg/cm . The second layer was a 1 mm impermeable layer made of 65% Graphite, 15% Teflon and 20% Graphite fibers, pressed under 1000 kg/cm2 . Before assembling the cell, the carbon electrodes were sprayed with the 1M NaOH solution. The capacitor was charged and discharged under a current of 10 mA, using Maccor 2000 Tester with voltage of 0.01 to 1.0V, and had a capacitance of 0.1F.

Example 6 A membrane film was manufactured by mixing 0.85 gr of Kynar PVDF 2801-00 with 0.682 gr of Degussa Titandioxid P25,- 0.368 gr of Johnson Matthey Silicon (IV) Oxide, 15 ml cyclopentanon and 2.4 ml of PC. The viscous mixture was poured on a Teflon plate as described in the preceding examples. A flexible, opaque white film having very good mechanical strength was thus obtained.

Example 7 The pore size distribution of the ICM described in sample 9 (Table 1) was measured by using Quantachrome NOVA 2200 Surface Area Analyzer. It was found that a significant volume of the material tested had nanosize pores having a characteristic dimension of less that 3 nm. These nanosize pores have good retention capability for the electrolyte and are small enough to prevent gas bubbles to cross over ICM. This property is of importance in the case where the ICM of the invention is used for fuel cell applications.

Example 8 An ionic conducting membrane (ICM) was made by immersing the film of sample No. 9 (Table 1) in a 2M NH4C1 aqueous solution. The conductivity was measured at room temperature by using AC impedance spectroscopy Solartron model SF 1260. The measurements were made while using two 1 cm stainless steel electrodes. The conductivity was 0.04 S/cm.

Example 9 A cell having two Ti foils as' current collectors was assembled. The 100 microns thick anode was 60% porous and the solid matrix consisted of 35% (v:v) PVDF and 65% fine Zn powder which contains 0.1% Hg. The 100 microns thick cathode was 60% porous and its solid matrix consisted of 35% (v:v) PVDF, 5% fine powder graphite and 60% fine powder MnO2. A 100 microns thick ICM prepared in Example 8 was hot pressed between 1 2 2 cm cathode and 1 cm anode. The whole cell was immersed in 2M NH4C1 aqueous solution in order to fill all the pores. The excess of electrolyte was cleaned and the cell was held between the two Ti current collectors. The cell was dischrged at 0.1 mA for 15 hours to 0.7V end voltage.

Example 10 A Zn air cell was assembled according to Example 9, except the electrolyte was 1M KOH. The cathode used was a commercial air electrode purchased from Electrochem. The cell was discharged at 0.1 mA for 25 hours and at an average voltage of 1.2 V.

Claims

126830/2 - 17 - CLAIMS:

1. An ion conducting matrix comprising: (i) 5% to 60% by volume of an inorganic powder having a good -aqueous electrolyte absorption capacity; (ii) 5% to 50% by volume of a polymeric binder that is chemically compatible with an aqueous electrolyte; and (iii) 10 to 90% by volume of an aqueous electrolyte, wherein the inorganic powder comprises essentially sub-micron particles and said aqueous electrolyte consists of an aqueous soluble compound selected from a salt, a base or mixtures thereof.

2. A matrix according to claim 1, wherein said inorganic powder is a powder having a surface area of at least 10 m /g and possesses a good absorption capability for said aqueous electrolyte.

3. A matrix according to claim 1 or 2, wherein said inorganic powder is a member selected from the group consisting of SiO2, ZrO2, B2O3, T1O2, AI2O3 and optionally hydroxides and oxy-hydroxy of Ti, Al, B and Zr, and any combination thereof.

4. A matrix according to any one of the preceding claims, wherein said polymeric binder is a material which is a member selected from the group consisting of: polyvinilyden fluoride, polyvinilyden fluoridehexafluoro-propylene, poly(tetrafluoroethylene), poly(methylmethacrylate), polysulfone amide, poly(acrylamide), polyvinyl chloride, acrylonitrile, polyvinyl fluoride and any combination thereof.

5. A matrix according to claim 1, wherein said aqueous soluble salt is a member selected from the group consisting of alkali metal salts, alkali earth metal salts, R4NX, where R is an organic radical and X is an anion derived from an inorganic acid, NH4CI, ZnCl2 and any combinations thereof.

6. A matrix according to claim 1, wherein said aqueous soluble base is a member selected from the group consisting of R4NOH where R is hydrogen 126830/2 18 - or an organic radical, alkali or alkali earth base compounds and any combinations thereof.

7. A matrix according to claim 1, wherein said aqueous electrolyte is used in an aqueous solution having a molar concentration of from about 0.1M to about 10M.

8. A matrix according to claim 7, wherein the aqueous electrolyte has a molar concentration of from about 1M to about 5M.

9. A membrane comprising the ion conducting matrix of any one of the preceding claims, wherein said inorganic material is electronically non-conductive material.

10. A membrane according to claim 9, wherein the inorganic powder of the matrix comprises particles that are essentially of a size of less than 150 nm.

11. A membrane according to claim 9, wherein said membrane comprises pores with a size which is essentially smaller than 50 nm.

12. A membrane according to any one of the claims 9 to 11, wherein the inorganic powder of the matrix is treated with an acid or a base prior to the preparation of the membrane.

13. A membrane according to any one of claims 9 to 12 which further comprises an electronic non-conductive reinforcing elements.

14. A composite electrode comprising 10 to 70% by volume of the matrix of any one of claims 1 to 8 and the balance is an electrode material.

15. A method for casting a membrane of claims 9 to 12 which comprises the following steps: (i) preparing a mixture comprising an inorganic powder, a polymeric binder that is chemically compatible with an aqueous electrolyte, at least one solvent characterized in having a high boiling point of above 100°C and at least one low boiling point solvent, having a boiling point lower than that of the high boiling point solvent(s), in which the polymeric binder is soluble or form a gel at the casting temperature; (ii) casting a film out of the mixture; (iii) allowing the low boiling point solvent to evaporate from the mixture, thus forming a solid film; (iv) washing the solid film and replacing the high boiling point solvent with the aqueous electrolyte solution to be included in the membrane.

16. A method for casting a composite electrode of claim 14 which comprises the following steps: (i) preparing a mixture comprising an inorganic powder, a polymeric binder that is chemically compatible with an aqueous electrolyte, at least one solvent characterized in having a high boiling point of above 100°C, at least one low boiling point solvent, having a boiling point lower than that of the high boiling point solvent(s) in which the polymeric binder is soluble or form a gel at the casting temperature, and a further powder comprising electrode material; (ii) casting a film put of the mixture; (iii) allowing the low boiling point solvent to evaporate from the mixture, thus forming a solid film; 126830/2 - 20 - (iv) washing the solid film and replacing the high boiling point solvent with the aqueous electrolyte solution to be included in the membrane.

17. -17. A method according to claim 15 or 16, wherein the high boiling solvent is a water soluble solvent.

18. A method according to claim 15 or 16, wherein the high boiling point solvent is selected from the group consisting of propylene carbonate, ethylene carbonate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate and the like or any combinations thereof.

19. A method according to claim 15 or 16, wherein the low boiling point solvent is a member selected from the group consisting of tefrahydrofuran, DME, cyclopentanon, acetone, N-methyl pyrrolidon, dimethylacetamide, methylethylketone, dimethyl-formamide, or any combination thereof.

20. A method for preparing a membrane of claims 9 to 12 by extrusion which comprises the following steps: (i) preparing a mixture comprising an inorganic powder, a polymeric binder that is chemically compatible with an aqueous electrolyte and at least one solvent characterized in having a boiling point of above 90°C in which the polymeric binder is at least partially soluble or form a gel at extrusion temperature; (ii) heating the mixture to its softening temperature; (iii) forming a film out of the mixture by hot extruding the softened mixture; (iv) cooling the film thus formed; (v) washing the solid film and replacing the solvent with the aqueous electrolyte solution to be included in the membrane. \ 126830/2 • 21 -

21. A method for preparing a composite electrode of claim 14 by extrusion which comprises the following steps: (i) preparing a mixture comprising an inorganic powder, a polymeric binder that is chemically compatible with an aqueous electrolyte, at least one solvent characterized in having a boiling point of above 90°C in which the polymeric binder is at least partially soluble or forma gel at extrusion temperature and a further powder comprising electrode material; (ii) heating the mixture to its softening temperature; (iii) forming a film out of the mixture by hot extruding the softened mixture; (iv) cooling the film thus formed; (v) washing the solid film and replacing the solvent with the aqueous electrolyte solution to be included in the membrane.

22. A method according to claim 20 or 21, wherein said solvent is a water soluble solvent.

23. A method according to claim 20 or 21, wherein said solvent is a member selected from the group consisting of propylene carbonate, diethyl carbonate, dimethyl carbonate, butyrolactone, methyl isoamyl ketone, cyclohexanone, dialkyl phthalate, glycerol triacetate or any combinations thereof.

24. An electrochemical cell comprising a membrane of any one of claims 9 to 13.

25. An electrochemical cell comprising at least one electrode of claim 14. 126830/2 • 22 -

26. An electrochemical cell according to claim 24 or 25, wherein said electrode material is a member selected from the group consisting of carbon, graphite and a combination thereof.

27. -27. An electrochemical cell according to claim 24 or 25, wherein the anode active material is selected from Cd, Zn, Al or their alloys and the cathode active material is selected from Mn02, silver oxides and NiOOH.

28. An electrochemical cell comprising a membrane as defined in any one of claims 9 to 13, a Zn or Al anode and oxygen or air electrode which consists of a double layer film, wherein the air side is hydrophobic and the side close to the ionic membrane is hydrophilic.

29. An electrochemical cell according to claim 28, wherein the air electrode catalysts are compatible with the aqueous solution of the ionic conductive membrane and are selected from Pt, Pd, Au, Ag, Cu, Mn, W the oxides thereof or metal-porphyrin complexes of these salts.

30. An electrochemical cell according to claim 24 or 25, wherein said electrode material is a metal oxide selected from among RuO2, WOx, and MnO2.

31. An electrochemical cell according to claim 24 or 25, wherein said cell is a single structure unit manufactured by hot pressing the electrodes on both sides of membrane of claims 9 to 13.

32. A fuel cell comprising an ion conducting membrane of any one of claims 9 to 13.

33. A water electrolizer comprising an ion conducting membrane of any one of claims 9 to 13. For the Applicants, REINHOLD COHN AND PARTNERS By: 5 ,\x>^