Bbc Brown, Boveri & Company, Limited

Edwin Muller

Moritz Braun

Anna Kaufmann

Especially for bipolar membrane electrolysis cells, cathodic current collectors (8) are required which have a high electrical conductivity, a large contact surface area and a sufficient porosity to ensure the passage of reaction educts and products, for example, water and gas. At the same time, they should be chemically, mechanically and thermally stable. No protective voltage should be required while the cells are closed down. The current collector consists of graphite powder (12) of high purity, having particle sizes in the range from 10 .mu.m-200 .mu.m, and carbon fibres (13) which are irregularly distributed therein and have lengths from 1 mm to 30 mm, the graphite powder/carbon fibre mass ratio being in the range from 10:1 to 30:1. The binder used is polyvinylidene fluoride. For producing the current collector, the binder is dissolved in, for example, dimethylformamide. Graphite powder and carbon fibres are then added and the resulting lubricating grease-like mass is brought to the desired thickness by spreading on a glass plate and is dried for about 1 hour at about 50.degree. C. The current collector can be used especially for water electrolysis, chlor-alkali electrolysis and hydrochloric acid electrolysis.

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Zurich, Switzerland

Edwin Muller