Gas-diffusion electrode

摘要

A gas-diffusion electrode comprises two coarse pored working layers 2, each of which is bonded to a fine pored surface layer 1, separated by and bonded to a coarser pored gas distributing layer 6, the layers being formed and bonded together by sintering. A porous frame 15 surrounds the electrode. The electrode was made by compressing at 200 kg./cm.2 14 gm. carbonyl nickel (particle size less than 5 microns) in an annular mould to form frame 15 and introducing and lightly compressing one of the working layers 2 which comprises 5 gm. of a double skeleton catalyst, e.g. 3 gm. carbonyl nickel powder and 2 gm. Raney alloy (50/50 nickel, aluminium, particle size 35-50 microns. 9 gms. of carbonyl nickel and 4 gms. of potassium chloride crystals (particle size 200-400 microns) forming the coarse pored gas distributing layer 6 is introduced and lightly pressed followed by another 5 gms. of the above mentioned working layer powder. The three layers were compressed at 680 kg./cm.2 to the height of the frame 15. The structure so formed was placed in a mould of the same diameter, the bottom of which was lined with a powdered surface layer, and was covered with a powdered surface layer. Each surface layer 1 comprised 2.4 gm. carbonyl nickel and 1.6 gm. of Raney alloy, e.g. 50/50 aluminium-nickel particle size 7.5-9 microns. The resultant body was compacted at 3000 kg./cm.2 at a temperature of 370 DEG C. and then sintered in an atmosphere of hydrogen for twelve minutes at 820 DEG C. The inactive components of the Raney alloy and the potassium chloride of the gas distributing layer were leached out. Wires of magnesium, zinc or aluminium, which may be leached out, or materials which vaporize at the sintering temperature, e.g. citric acid, ammonium carbonate, or ammonium salts of organic materials, may be embedded in the coarse pored gas distributing layer 6 to form a capillary system. The gas distributing layer 6 may be made from a coarse grained powder with either common salt or aluminium shot as the soluble filler. Specifications 806,664, 907,907, 913,595, 922,462 and 931,778 are referred to.