Solid Inorganic Electrolyte Regenerative Fuel Cell System

Abstract

Sintered zirconium phosphate membranes containing zeolites have significant water absorptive capacities over a temperature range of from ambient to 150°C. This feature makes them sufficiently conductive for fuel cell applications over this temperature range. Such membranes have transverse strengths of 5000 to 6000 psi. They readily gain and lose water vapor in a reversible manner while maintaining good stability. This accounts for promising results obtained to date for regenerative hydrogen--oxygen fuel cells using this membrane. In addition to presenting regenerative hydrogen-oxygen fuel cell data, water absorptivity and conductivity data are given and interpreted in terms of membrane composition and structure.'"phe earliest reported use of zirconium phosphate membranes as a solid A electrolyte for hydrogen-oxygen fuel cells dates back to 1961 (9,10, IS). Astropower Laboratory has been investigating the electrochemical behavior of modified zirconium phosphate structures from both a fundamental as well as a developmental aspect. Significantly, a comprehensive investigation of composition and fabrication techniques, as they are related to membrane strength, conductivity, and hydrolytic stability, has led to deriving useful solid electrolyte structures. This is evidenced by successful hydrogen-oxygen fuel cell tests over the temperature range of 25° to 148°C. (6).Most characteristic of these membranes is an incorporated zeolite component serving a water-balancing function by virtue of its high affinity for water and low rate of desorption. In this manner, the conductivity of the membrane is maintained at a suitable level over wide temperature 17

Liquid fuel cells

“…Composite membranes based on both fluorinated and non-fluorinated materials, e.g., polysulfone polymers and inorganic proton conductors are used to achieve higher operating temperatures and a lower humidity [ 8 ]. Solid inorganic proton conductors (e.g., sintered zirconium phosphate) allow for increasing the working temperature up to 150–250 °C [ 9 ]. Only platinum group metal (PGM) electrocatalysts are stable enough in the low-pH environment of PEMs.…”