Hydrogen/oxygen regenerative fuel cell stores electrical energy efficiently and inexpensively. The fuel cell has a high energy-to-weight ratio, and is adapted for a large number of cycles with deep discharge

Doyle, H.

Frank, H.

Stephens, C. W.

English

NASA Technical Reports Server

December 1965
	 Brief 65-10363 
NASA TECH BRIEF iw 
NASA Tech Briefs are issued by the Technology Utilization Division to summarize specific 
technical innovations derived from the space program. Copies are available to the public from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia, 22151. 
Regenerative Fuel Cell Combines High Efficiency with Low Cost 
Tubing 
Electrolyte 
The problem: To provide an electrical energy stor-
age medium that is lightweight, efficient, and inexpen-
sive. Conventional storage batteries exhibit poor en-
ergy-to-weight ratios and are generally unreliable over 
a large number of cycles especially where deep dis-
charge is a duty requirement. Prior-art fuel cells attain 
relatively poor efficiency, exhibit limited current 
density, and have limited useful life. 
The solution: A hydrogen/oxygen regenerative 
fuel cell that features high efficiency and low cost and 
is adapted for a large number of cycles with deep dis-
charge. The unit output achieves a high energy-to-
weight ratio. 
How it's done: The fuel cell consists of two gas-
permeable electrodes contacting and separated by a 
body of electrolyte, all completely enclosed in a hous-
ing. The first electrode is of inert platinized nickel, 
the second electrode is of silver, and the electrolyte 
body is a fine, porous, nonconducting bed of asbestos
that is partially saturated with an aqueous solution 
containing 35% potassium hydroxide by weight. When 
the cell is initially charged with a predetermined 
amount of electrical energy, electrolysis occurs in the 
electrolyte solution producing hydrogen gas from the 
first electrode and oxygen gas from the second elec-
trode. The hydrogen gas is stored in a container con-
nected to the first-electrode side of the housing and its 
pressure is controlled by a regulator connected to the 
other side of the housing and containing a flexible 
diaphragm through its center. Substantially all of the 
oxygen gas produced at the second electrode immedi-
ately combines with it to form silver oxide. Balancing 
of the gas pressures within the system is by action of 
the regulator diaphragm being expanded by the hydro-
gen gas so as to reduce the volume containing the 
oxygen gas. 
When a predetermined amount of electrical, energy 
is discharged from the cell, the silver oxide is reduced 
to pure silver and the gaseous hydrogen reacts With the 
(continued overleal) 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19650000361 2020-03-11T17:24:39+00:00Z
hydroxyl ions formed at the silver electrode to produce 
water which is absorbed into the electrolyte bed. Thus 
the cell is regenerative, and, upon application of 
another charge, the gas-producing cycle will be re-
peated. 
Notes: 
I. This cell was charged at room temperature for a 
period of 2 hours with a current of 50 milliamps at 
1.16 volts. It was then discharged at room tem-
perature for 2 hours and delivered a current of 50 
milliamps at 1.12 volts. Thus, voltage efficiency 
was about 96.5%, current efficiency about 95%, 
and power efficiency about 91.7%. Prior art norm-
ally failed to achieve 70% efficiency.
Energy-to-weight ratios in the vicinity of 70 watt-
hours per pound have been achieved. Conventional 
wet batteries normally deliver from 5 to 15 watt-
hours per pound. 
Patent status: Title to this invention has been 
waived under the provisions of the National Aero-
nautics and Space Act (42 U.S.C. 2457 (f)), to Elec-
tro-Optical Systems, Inc., 300 North Halstead Street, 
Pasadena, California, 91107. 
Source: Harlan Doyle, Harvey Frank, and

Charles W. Stephens of Electro-Optical

Systems, Inc. under contract to

Western Operations Office

(WOO-090) 
Brief 65-10363	 Category 01


Regenerative fuel cell combines high efficiency with low cost

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