The separator technology is a critical element in the nickel-hydrogen (Ni-H2) systems. Previous research and development work carried out at NASA Lewis Research Center has determined that separators made from zirconium oxide (ZrO2) and potassium titanate (PKT) fibers will function satisfactorily in Ni-H2 cells without exhibiting the problems associated with the asbestos separators. These separators and their characteristics were previously discussed. A program was established to transfer the separator technology into a commercial production line. A detailed plan of this program will be presented and the preliminary results will be discussed

Gonzalez-Sanabria, O. D.

English

NASA Technical Reports Server

NASA Technical Memorandum 87332
Nickel-Hydrogen Separator Development
N86-26677
CSC1 10C
Unclas
G3/44 43289
Olga D. Gonzalez-Sanabria
Lewis Research Center
Cleveland, Ohio
Prepared for the
21st Intersociety Energy Conversion Engineering Conference (IECEC)
cosponsored by the ACS, SAE, ANS, ASME, IEEE, AIAA, and AIChE
San Diego, California, August 25-29, 1986
NASA
https://ntrs.nasa.gov/search.jsp?R=19860017205 2020-03-20T14:30:59+00:00Z
NICKEL-HYDROGEN SEPARATOR DEVELOPMENT
Olga D. Gonzalez-Sanabrla
National Aeronautics and Space Administration
Lewis Research Center
Cleveland, Ohio 44135
SUMMARY
The separator technology 1s a critical element 1n the Nickel-Hydrogen
(N1-H2) systems. Previous research and development work carried out at NASA
Lewis Research Center has determined that separators made from zirconium oxide
(ZrOg) and potassium tttanate (PKT) fibers will function satisfactorily 1n
N1-Hg cells without exhibiting the problems associated with the asbestos
separators. These separators and their characteristics have been previously
discussed. A program has been established to transfer the separator technology
Into a commercial production line. A detailed plan of this program will be
presented and the preliminary results will be discussed.
INTRODUCTION
A separator development program have been 1n effect at NASA Lewis Research
Center for a number of years. Lately this development program have been
focused on the development of new non-asbestos separators for N1-H2 cells and
batteries. These separators were to have equal performance to asbestos while
eliminating the present separator problems associated with the asbestos avail-
ability and environment. A new set of separators made of potassium tltanate
(PKT) and zirconium oxide (Zr02) fibers and a binder have been developed and
tested as previously reported (ref.'l). To date the new separator material
have been manufactured manually by the use of handsheet molds capable of pro-
ducing 8 1n. square sheets at a very low production rate. In order to demon-
strate the feasibility of using this new separator material 1n a variety of
different applications 1t would be necessary to produce longer sheets at higher
production rates. In an effort to bridge the gap between the handsheet oper-
ation and the commercial processes a research program has been put Into effect
with the Paper Science and Engineering Department of the Miami University of
Ohio. The objective of this communication 1s to present the research program
plan and Its status and discuss the preliminary results 1n relation to their
effect on nickel-hydrogen cells and batteries.
SEPARATOR TECHNOLOGY
The separator development program will consist of three phases «w1th the
objective of demonstrating the feasibility of manufacturing the new separator
materials using a standard paper making techniques. The final result to be a
separator which, by the nature of the process, will be more uniform and easily
reproduced. These objectives will be accomplished 1n three different phases:
Phase I - Duplication of NASA Handsheet Procedures
The objective of this phase 1s to familiarize the Miami University staff
with the working materials and their particular characteristics and behavior.
NASA handsheet are to be duplicated so as to establish the procedure and the
required properties of the final mat. The availability of new materials or
modifications 1n those used by NASA and their effect will be studied and
attempts made to produce these handsheets using standard paper forming oper-
ations.
Phase II - Determination of Conditions For Paper Machine Run
This phase 1s designed to Identify the conditions and composition required
to produce an acceptable handsheet employing a normal forming fabric with a
handsheet mold and to Identify the starting conditions to be used 1n the
Initial paper machine experimental runs. Of Interest 1n this phase are the
forming fabrics, fine solids retention, sheet dewaterlng, and distribution of
materials 1n the handsheets. Also, the effect of fillers and binders on the
characteristics of the separator with special Interest on Increasing the bubble
pressure.
Phase III - Production of Separator Paper on the Pilot Machine
The success of the paper machine runs will depend largely on the Miami
University skills and expertise coupled with the knowledge gained 1n phases I
and II of therprogram. The conditions, the composition and order of addition,
of the components that produce the best papers 1n phases I and II will serve
as the starting points for the paper machine experiments. Subsequent paper
machine trials will be designed based on the results of the Initial run plus
any additional .Information gained from "bench-scale" experiments that will be
run throughout this phase. The production of an acceptable separator that
could be reproduced and meets the desired performance characteristics 1s the
ultimate goal of phase III and the program.
DISCUSSION
The Lewis separators were made on a Williams sheet mold and were filtered
onto a closely knitted filter sheet. This was only an Interim solution to the
retention problems posed by the small PKT fiber size. It was later discovered
that the distribution of material throughout the sheet was not uniform. The
use of the filter sheet also made 1t very difficult to adapt to an effective
manufacturing production processes. An attempt was made by a commercial manu-
facturer to produce the separator handsheets on sheet molds employing normal
open-mesh fabrics but resulted 1n poorly formed sheets that did not have
desirable properties. Plnholes occurred frequently and 1t was often difficult
to remove the sheets from the sheet mold. These problems are probably related
to poor retention of fine solids 1n the sheet (plnholes) as well as Inadequate
dewaterlng (low web strength). An SEM picture?Which represents this phenomena
1s shown 1n figure 1.
To solve the above problems, efforts will be made to Increase the reten-
tion of PKT and dewaterlng rate during handsheet formation. The Improvement
of sheet formation (distribution of mass throughout the sheet) will also be
Investigated, which will enhance wet web formation and Improve most other pro-
perties as well.
Since the Initial Lewis separators can not be reproduced under the paper
machine environment due to changes 1n the manufacturing procedure, an attempt -
1s being made to reproduce the separator properties when using the new tech-
niques. A new development on Zr02 fibers has occurred since the Lewis sep-
arators were made. There 1s a new fiber now available Zr02(TOW) which 1s
more flexible and has a longer length than those available to us before. This
Increases the strength of the mat and makes 1t easier to form the sheets on a
standard forming fabric. Preliminary sheets were made which formed very nicely
on the standard forming sheets. As shown 1n Table I these results are very
encouraging, reproducing all the desired properties except for a lower bubble
pressure. In the separators with the lower Zr02 composition, problems
started to develop where 1t became difficult to remove the sheet from the
forming fabric. When the standard Zr02 bulk fibers where used similar prob-
lems were encountered. Experiments are now being designed with the purpose of
Improving the bubble pressure by means of filler addition, binder composition
and applied pressure, among others. The Impact of this new fiber on separator
characteristics and cost needs to be evaluated. Since the cost of the new
fiber 1s much more than the original bulk fiber an attempt will be made to
find the best composition mixture using both fibers.
In addition to these experiments, the effect of the binder on material
strength (wet web) will also be Investigated.- Although some binder tests were
performed at Lewis these experiments become much more Important at this state
of development. The amount of binder on the Lewis separators could not be
determined and the actual retention seemed to have been quite low judging from
SEM pictures taken. The Increased binder retention as seen 1n the Improved
sheet flexibility and strength of the Miami University separators could sig-
nificantly affect the separator characteristics for the better. These could
also be affected by the binder formulation. Previous testing done has shown a
greater strength can be achieved with a polyacrylic add binder but,water
retention will also be Increased possibly affecting the dewaterlng process 1n
an adverse manner. These separators will be subjected to the same screening
tests as 1n reference 1.
As was previously shown (ref. 2) the separator effects the voltage char-
acteristics 1n the cell. We also know that 1t also effects the volume tol-
erance of the cells (ref. 3) thereby possibly controlling the cycle life. The
pore size distribution of these separators have been and will continue to be
closely monitored to ensure effective pore size distribution. The separator
is also required to effectively control the rate and location of the oxygen
recombination as have been designed into the Lewis advanced IPV and Bipolar
design configurations (ref. 4). At the end of this program this technology
will be ready to be translated to other paper machines for large scale pro-
duction of these separators. They~w1ll be verified by short term character-
ization and long term cycling in nickel-hydrogen cell hardware with subsequent
post test analysis.
CONCLUDING REMARKS
The Impact of these separators an nlckelhydrogen systems 1s expected to
result 1n equal or better performance than asbestos, Increased cycle life and
Improved heat and electrolyte management 1n coordination with advanced designs.
There are currently no separators that will accomplish these goals since the
current supply of good asbestos fibers 1s limited and 1s rapidly being
consumed. Preliminary results are encouraging. These new separators are
expected to be ready and available to the battery community by 1987.
ACKNOWLEDGEMENT
The author gratefully acknowledges the assistance of Dr. William Scott and
Mr. Timothy L1ntz form Miami University for their assistance and for supplying
the separator samples described 1n the paper.
REFERENCES
1. Gonzalez-Sanabrla, O.D.; Manzo, M.A.: Separator Development and Testing
of Nickel-Hydrogen Cells. Advanced Energy Systems-Thelr Role 1n Our
Future, vol. 1, 19th IECEC, American Nuclear Society, 1984, pp. 279-286.
2. Stadnlck, S.J., et al.: Nickel-Hydrogen Battery Advanced Concept
Development Program. Hughes Aircraft Corporation, Technology Division,
AFAPL-TR-79-2005 IR-2, 1978.
3. Abbey, K.M.; Thaller, L.H.: Pore Size Engineering Applied to Starved
Electrochemical Cells and Batteries. Energy-The Spark and Lifeline of
Civilization, vol. 2, 17th IECEC, IEEE, 1982* pp. 757-764.
4. Thaller, L.H.; Manzo, M.A.; Gonzalez-Sanabrla, O.D.: Design Principles
for N1-H2 Cells and Batteries. Engery for the Twenty-First Century,
vol. 1, 20th IECEC, SAE, 1985, pp. 145-150.
TABLE I. - SEPARATOR PROPERTIES
Composition
80% PKT
20% Zr02
10% EBL
80% PKT
20% Zr02(TOW)
10% EBL
100% PKT
5% Zr02(TOW)
10% EBL
Resistivity,
ohm-cm
2
2
2
Electrolyte
retention,
percent
171
147
172
Porosity,
percent
69
80
86
Bubble3
pressure,
ps1
>30
9
12
•
aBest sample
ORIGINAL P&SE 5S
OF POOR QUALITY
51iX 15KU WEM9MH P-80811
IK
Figure 1. - Separator deffects.
1. Report No.
NASA TM-87332
2. Government Accession No. 3. Recipient's Catalog No.
4. Title and Subtitle 5. Report Date
Nickel-Hydrogen Separator Development
6. Performing Organization Code
506-41-21
7. Authors)
Olga D. Gonzalez-Sanabrla
8. Performing Organization Report No.
E-3076
10. Work Unit No.
9. Performing Organization Name and Address
National Aeronautics and Space Administration
Lewis Research Center
Cleveland, Ohio 44135
11. Contract or Grant No.
12. Sponsoring Agency Name and Address
National Aeronautics and Space Administration
.Washington.- D.C. 20546
13. Type of Report and Period Covered
Technical Memorandum
14. Sponsoring Agency Code
15. Supplementary Notes
Prepared for the 21st Intersodety Energy Conversion Engineering Conference
(IECEC), cosponsored by the ACS, SAE, ANS, ASME, IEEE, AIAA, AND AICHE,
San Diego, California, August 25-29. 1986
16. Abstract
The separator technology 1s a critical element 1n the Nickel-Hydrogen (N1.-H2)
systems. Previous research and development work carried out at NASA Lewis
Research Center has determined that separators made from zirconium oxide
(Zr02) and potassium tltanate (PKT) fibers will function satisfactorily 1n
N1-H2 cells without exhibiting the problems associated with the asbestos
separators. These separators and their characteristics have been previously
discussed. A program has been established to transfer the separator technology
Into a commercial production line. A detailed plan of this program will be
presented and the preliminary results will be discussed.
17. Key Words (Suggested by Author(s))
Akallne batteries; Separators;
Zirconium oxide; Potassium tltanate;
Nickel-Hydrogen
19. Security Classif. (of this report)
Unclassified
18. Distribution Statement
Unclassified
STAR Category
20. Security Classif. (of this page)
Unclassified
- unlimited
44
21. No. of pages 22. Price*
*For sale by the National Technical Information Service, Springfield, Virginia 22161
National Aeronautics and
Space Administration
Lewis Research Center
Cleveland. Ohio 44135
Official Business
Penalty for Private Use $300
SECOND CLASS MAIL
ADDRESS CORRECTION REQUESTED
Postage and Fees Paid
National Aeronautics and
Space Administration
NASA-451
NASA


Nickel-hydrogen separator development

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server