Bifunctional gas diffusion electrodes employing wettable, non- wettable layered structure using the mud-caking concept

摘要

A bifunctional gas diffusion electrode used in an electrochemical energy cell wherein a multi-ply composite layer containing an embedded metal screen current collector provides electrical power via the reduction of oxygen from air in the presence of an electrolyte and a catalyst. The electrode stores electrical power via the evolution of oxygen in the presence of an electrolyte and another catalyst. More than one composite layer may be used. Each ply of any particular composite layer is made of carbon-containing material of varying wettability and a fluorocarbon material. Each hydrophobic central ply contain a metal screen current collector. These central plies are prepared in a way to foster fissuring throughout the ply. Such fissuring, along with a hydrophilic impregnate forced into these fissures, permits controlled electrolyte penetration of the hydrophobic ply. Hydrophilic end plies sandwich the central ply and produce a large surface area for catalyzed oxygen reduction during the cell discharge cycle or catalyzed oxygen generation during cell charge cycle.