Abstract:
The invention pertains to a process for operating a polymer electrolyte membrane fuel cell (PEMFC), said PEMFC comprising:(a) a membrane comprising at least one fluorinated ionomer [polymer (I)] comprising recurring units derived from tetrafluoroethylene (TFE) and from at least one monomer of formula (M): wherein m is an integer between 1 and 6 and X' is chosen among halogens (Cl, F, Br, I), -O - M + , wherein M + is a cation selected among H + , NH 4 + , K + , Li + , Na + or mixtures thereof, said polymer (I) having an equivalent weight (EW) of from 700 to 850 g/eq.; (b) a cathode; (c) an anode; said process comprising: (i) feeding gaseous reactants at the electrodes at a relative humidity of at most 66 %; (ii) maintaining an average current density between 0.05 and 1.5 A/cm 2 ; and(iii) maintaining an average temperature of more than 65 °C.
Abstract:
The invention describes a new design of ionomer membrane fuel cell stack comprising a multiplicity of stainless steel bipolar plates, electrodes, membranes and perimetrical sealing gaskets enclosed between compression plates. The novel design is directed to prevent the build up of metal ions in the membranes and the consequent voltage decay; for this purpose, the lateral migration inside the ionomer membranes of the metal ions contained in the cooling fluid is prevented.
Abstract:
The present invention discloses an electrochemical generator fed with reactant gases, and in particular a fuel cell fed with a hydrogen-containing gas and with air at near ambient pressure. The electrochemical generator is characterised by asymmetry of the pressure drops localised in the distributing and collecting channels, wherein, in particular, the pressure drop concentrated in the collecting channels is substantially higher than that concentrated in the distributing channels. Moreover, the pressure in the active areas of the generator substantially coincides with the feeding one. Such a result is obtained by differentiating the design of the distributing channels from the one of the collecting channels, whose passage section is lowered and/or whose length is increased and/or whose amount is decreased.
Abstract:
A liquid composition comprising at least one aprotic organic solvent and at least one fluorinated ion exchange polymer which consists of recurring units derived from a chlorofluoroolefin of formula CF2=CCIY, wherein Y is F or CI, and from at least one fluorinated functional monomer selected among those of formula CF2 =CF-O-(CF2CF(CF3)O)m-(CF2)nSO2X, wherein m is an integer equal to 0 or 1, n is an integer from 0 to 10 and X is chosen among halogens (CI, F, Br, I), -O-M+, wherein M+ is a cation selected among H+, NH4 +, K+, Li+, Na+, or mixtures thereof is disclosed. The liquid composition is suitable for the preparation of ion exchange membranes, in particular composite membranes, for use in fuel cell applications.
Abstract:
The invention pertains to a process for stabilizing a semi-crystalline fluoropolymer comprising ion exchange groups, said process comprising: suspending at least one semi-crystalline fluoropolymer having ion exchange groups [polymer (I)] in at least one fluorinated organic dispersing medium [medium (M)] so as to obtain a dispersion (D) of polymer (I) in a dispersing medium (M); contacting said dispersion (D) with fluorine under irradiation with U. V. radiation so as to obtain a stabilized polymer. Still objects of the invention are a stable semi-crystalline fluoropolymer as above defined having a low amount of unstable ends groups of -COF type, the use of the stabilized fluoropolymer obtained by the process or of the stable fluoropolymer in fuel cells devices, a membrane and a membrane-electrode assembly comprising said fluoropolymers.
Abstract:
The present invention describes a membrane fuel cell capable of operating in a stable fashion at high currently density under dry reactant gas feed at near-atmospheric pressure. This result is obtained by employing internal porous gas distributors, such as three-dimensional reticulated materials, sintered materials, juxtaposed meshes or expanded sheets, and at the same time by countercurrent-feeding the gas reactants, preferably ambient air, from the bottom. In one preferred alternative liquid water is injected from the bottom into the air feed: with these operating conditions, an extremely simplified stable functioning is obtained, since the air and water flow-rates, adjusted as requested for the maximum nominal electrical output, are kept unvaried even at low or zero output conditions without the cell membrane undergoing dehydration.
Abstract:
A description is made of a flexible spacer for double glazing made of Polyisobutylene elastomer or butyl rubber IIR (simple or halogenated), suitably loaded with both reinforcing and inert fillers. The spacer can be cross-linked with sulphur or peroxides. The spacer is impermeable to moisture and has high low thermal conductivity gas sealing capacity, and incorporates moisture absorbing material. In particular, the spacer features - on each side wall - at least a small wave (13a) positioned immediately above the accumulation area of the internal or primary sealant (15) so as to ensure an optimal adhesion to the glass of the double/triple glazing unit within which the spacer is fitted and features at least one recess (13b), with a configuration such as to allow the external sealant to penetrate and create a strong mechanical bond between the two materials.
Abstract:
MEA 7-layer assemblies with gasket, comprising: - a film of ionomeric membrane (3), containing functional acid groups -SO 3 H and/or -COOH, having in at least one direction, called direction x, a size variation lower than 0.08%; - two GDL sheets (1) and (2) in porous material having on one surface an electrocatalytic layer, not shown in the Figures, of which: - the first sheet DGL (1) is coextensive with the membrane (3) surface, positioned so as to overlap thereto; - the second sheet GDL (2), having a lower width but the same length of the film of membrane (3), measured in the x direction; - the two sheets (1) and (2) placed so that the electrocatalytic layer comes into contact, respectively, with each of the two membrane faces; - a gasket positioned according to a frame shape along the assembly perimeter.
Abstract:
The invention describes a new design of ionomer membrane fuel cell stack comprising a multiplicity of stainless steel bipolar plates, electrodes, membranes and perimetrical sealing gaskets enclosed between compression plates. The novel design is directed to prevent the build up of metal ions in the membranes and the consequent voltage decay; for this purpose, the lateral migration inside the ionomer membranes of the metal ions contained in the cooling fluid is prevented.
Abstract:
The present invention discloses an electrochemical generator fed with reactant gases, and in particular a fuel cell fed with a hydrogen-containing gas and with air at near ambient pressure. The electrochemical generator is characterised by asymmetry of the pressure drops localised in the distributing and collecting channels, wherein, in particular, the pressure drop concentrated in the collecting channels is substantially higher than that concentrated in the distributing channels. Moreover, the pressure in the active areas of the generator substantially coincides with the feeding one. Such a result is obtained by differentiating the design of the distributing channels from the one of the collecting channels, whose passage section is lowered and/or whose length is increased and/or whose amount is decreased.