GB1416025A - Storage device comprising bipolar electrodes - Google Patents

Abstract

1416025 Storage device including bipolar electrodes OMF CALIFORNIA Inc 14 Nov 1972 [18 Nov 1971 (2)] 52623/72 Heading H1B A storage device of the metal/metal halide/ halogen type includes an aqueous metal halide electrolyte and at least two bipolar electrodes 13, 15, each bipolar electrode comprising a gas- and electrolyte-impervious wall 21 as a negative electrode which has a metal layer 23 on one surface and which is joined at its other surface to a porous member 25 forming the positive electrode, with a number of passageways 29 defined between the wall and porous member through which the electrolyte flows before it passes through the porous member 25 into the reaction zone 31 of an electrolytic cell formed by the negative electrode of one bipolar electrode and the positive electrode of an adjacent bipolar electrode. The porous member 25 is a unitary structure formed of amorphous carbon or graphite with a porosity such that a cross-section comprises 20-80% carbon with an average pore diameter of 5-300 microns and a minimum thickness of 0À3-3 mm. and a number of straight parallel grooves are formed therein which with the wall 21 define the passageways 29. Alternatively the porous member may be formed of sintered titanium or rutile with a noble metal or oxide catalyst, e.g. platinum or ruthenium oxide. The impervious wall 21 is preferably formed of graphite 0À3-4 mm. thick and has a coating 23 of 25-4000 microns thick of an electropositive metal from Group IIB or VIII, e.g. iron, cobalt, nickel or preferably zinc. Electrolyte from inlet duct 17 enters the passageways 29 as indicated at 37, passes through the porous member 25 and into the reaction zone 31 and is removed via the outlet manifold 19. A hole may be provided in the bipolar electrode at the top of each passageway 29. preferably formed through the porous member 25, to prevent the build-up of any gas in the passageways, Fig. 4 (not shown). A number of specific examples of storage devices of the preferred zinc/chlorine type are given. A diaphragm may be interposed between the porous carbon and the zinc to prevent contact of chlorine with the zinc. The storage device system is generally described in Specification 1,339,060. The porous carbon member 25 may be secured to the graphite wall 21 by the means disclosed in co-pending Application 52619/72.