New method makes solid ion exchange membrane electrolytes for use in hydrocarbon-oxygen and hydrogen-oxygen fuel cells. The membrane is a sintered composite of zirconia, phosphoric acid, and zeolite

Arrance, F. C.

Berger, C.

Kelmers, A. D.

English

NASA Technical Reports Server

September 1969
	 Brief 69-10451 
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information-,Springfield, Virginia 22151. 
Improved Inorganic Ion Exchange Membranes 
65°C for more than 500 hours at 0.5 volt and a 
current density of about 20 ma/cm 2
. Using propane 
as the hydrocarbon fuel, cell performance of 0.25 
volt and 14.9 ma/cm 2
 at 123°C was achieved. 
To make these membrane materials effective at tem-
peratures above 100°C, additives having controlled 
water vapor pressure characteristics can be admixed 
during the process of membrane preparation. Such 
materials as silicic acid, P 20 5 , Al 2 (SO 4) 3 , or other 
materials capable of retaining water at temperatures 
above 100°C can be used. A typical formulation 
in parts by weight is 1 part ZrPO 4
 and 0.5 part silicic 
acid. An example of the effectiveness of the water-
retaining additive in lowering the electrical resistance 
is noted in the following table: 
Temperature, °C
	 Type	 Resistance, Ohms 
115	 ZrPO4	 3000 
110	 ZrPO 4 + silicic	 30 
acid 
Note: 
Additional work is in progress to improve the 
performance of the membranes in both hydrocarbon-
oxygen and hydrogen-oxygen fuel cells. 
Patent status: 
Title to this invention has been waived under the 
provisions of the National Aeronautics and Space Act 
[42 U.S.C. 2457(f)], to the McDonnell Douglas 
Corporation, 3000 Ocean Park Boulevard, Santa 
Monica, California 90406. 
Source: C. Berger, A. D. Kelmers,

and F. C. Arrance of

McDonnell Douglas Corporation

under contract to

Lewis Research Center

(LEW-10737)
Category 03 
.
This document was prepared under the sponsorship of the National
	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States
	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States
	 will be free from privately owned rights. 
A new method has been developed for making 
solid ion exchange membrane electrolytes for use 
in hydrocarbon-oxygen and hydrogen-oxygen fuel 
cells. The membrane is a sintered composite of zir-
conia, phosphoric acid, and zeolite. A hydrogen-
oxygen fuel cell using this membrane with platinum 
black as a catalyst operates at 0.70 volt and a cur-
rent density of 30 ma/cm 2
 at 100°C; in this cell, 
the anode and cathode were comprised of a tantalum 
screen impregnated with platinum black and polytet-
rafluoroethylene for water balancing purposes. 
A requisite for fuel cell membranes is sufficient 
strength to be self-supporting and to resist vibra-
tional and other destructive forces. In addition, low 
electrical resistance and high current density are de-
sired. Inorganic membranes which satisfy these re-
quirements have been made by the typical prepara-
tive methods described below. 
In one method, the membrane is prepared by com-
pacting equal amounts of zirconia, phosphoric acid, 
and zeolite, and sintering the compact to 400°C. The 
sintered membrane is then saturated with 80 percent 
phosphoric acid and resintered at 500°C. The re-
sultant product is a membrane having a transverse 
strength of about 5500 psi and a resistance of 10 
ohm/cm 2
 at 25°C. Another method of preparation is 
to compact equal amounts of zirconia and phosphoric 
acid and sinter to 500°C. This material is then 
mixed wit1i equal parts by weight of phosphoric acid 
and zeolite and sintered at 500°C. The resulting 
membrane has a transverse strength of 5000 psi and 
an electrical resistance of less than 10 ohm/cm 2
 at 
25°C. 
A hydrogen-oxygen fuel cell using this solid mem-
brane electrolyte material has been operated at
https://ntrs.nasa.gov/search.jsp?R=19690000440 2020-03-16T17:59:52+00:00Z


Improved inorganic ion exchange membranes

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