Plastic-bound gas diffusion electrode containing a manganese oxide catalyst and process for preparing same

US4892637A · kind A · utility

Assignee

• Varta Batterie Aktiengesellschaft · DE

Inventors

• Hans Sauer · Bamberg, DE
• August Winsel

Key dates

• Filing date: Jun 23, 1988
• Grant date: Jan 9, 1990
• Expiry date: Jun 23, 2008

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02E60/50
• WIPO field: Electrical machinery, apparatus, energy
• WIPO sector: Electrical engineering

Abstract

A process which comprises thermally decomposing in an electrically heated vibrating helical conveyor, manganese carbonate (MnCO.sub.3 x H.sub.2 O) into a manganese oxide (predominantly of Mn.sub.2 O.sub.3 x Mn.sub.5 O.sub.8) catalyst at about 500.degree. C., and processing this catalyst into a highly active electrode paste by dry intensive mixing with a carbon-containing conductive material (carbon black, graphite or activated carbon) and PTFE as the binder. The resulting electrode paste can be rolled into a supporting net made from Ni or Ag. Also a two-step mixing process in which the catalyst powder is first premixed with small amounts of a conductive agent and a binder, compacted and granulated, and then combined with the larger residual amount of the intended amounts of conductive agent and binder in a second mixing step. The finished gas diffusion electrode has a biporous structure consisting of hydrophilic and hydrophobic pore canals, which is highly favorable for the transport processes and the electrochemical reaction. The electrode is useful in fuel cells, alkali chloride electrolyzers and air cells.