inorganic ion exchange membrane fuel cell

NASA CR-54199 e’-

Y

INORGANIC ION EXCHANGE MEMBRANE FUEL CELL

PERIOD ENDING 10 OCTOBER 1964

prepared for

NATIONAL AERONAUTICS AND SPACE ADMINISTRATION

CONTRACT NAS 3-6000

c

A S T R O P O W E R L A B O R A T O R Y PAULARINO AVE. NEWPORT BEACH. CALIFORNIA 2121 b

I .

Report SM-4622 1-Q1

INORGANIC ION EXCHANGE MEMBRANE FUEL CELL

National Aeronautics and Space Administration Contract NAS 3-6000

October 1964

MISSILE & SPACE SYSTEMS DIVISION ASTROPOWER LABORATORY

Douglas Aircraft Company, Inc. Newport Beach, California

LIST OF ILLUSTRATIONS

TABLE OF CONTENTS

LIST OF TABLES

1 . 0 SUMMATION AND CONCLUSION

2 . 0 INTRODUCTION

3 . 0 EXPERIMENTAL PROCEDURE, RESULTS AND DISCUSSION

3. 1 3. 2 Fuel Cel l Evaluation 3 .3 Resistivity Measurements 3 . 4 Hydrolysis Studies 3 .5

Membrane Composition and Fabrication Studies

Future Work for Second Quarter

4 . 0 PROJECT PERSONNEL

REFERENCE

Page

ii

... 111

1

2

2

8

8

SM-46221-Ql 1

LIST OF ILLUSTRATIONS

. Figure

1

2

3

4

5

6

7

8

9

Laboratory Fuel Cell

New Laboratory Fuel Cell

Current Density vs. Test Ce L fe at 62OC and 0 . 5 ~ for Fuel Cell Tes t No. 3, Table I.

Current Density VS. Test Cell Life at 62OC and 0 . 5 ~ for Fuel Cell Test No. 4, Table I.

Polarization Curves for Inorganic Membrane Fuel Cell - Test 1, Table 111





Follows Page

4

4

4

SM-46221-Q1 ii

LIST OF TABLES

~ Table -_I

I

I1

I11

IV

v

VI

VI1

Transverse Strengths i n psi of Pre-sintered Zirconium Dioxide-Phosphoric Acid - "Zeolon-H" Membranes

Planned Membrane Composition Studies

Inorganic Membrane Fuel Cell Operating Data on "Pre-SinteredI1 Zirconium Dioxide - Phosphoric Acid - "Zeolon H" Membranes

Inorganic Membrane Resistivity Data in Ohm-Cm on I l P re - sintered" Zi r c onium Dioxide- Phosphoric Acid Mixtures with Phosphoric Acid and "Zeolon-H" Sintered at Various Temperatures

Inorganic Membrane Resistivity Data in Ohm-Cm on I t P r e - sinter edVt Zirconium Dioxide- Phosphoric Acid Mixtures with Phosphoric Acid and llZeolon-H1f Sintered at Various Temperatures

Inorganic Membrane Resistivity Data in Ohm-Cm on "Pre- sintered" Zirconium Dioxide-Phosphoric Acid Mixtures with Phosphoric Acid "Zeolon-HI1 Sintered at Various Temperatures

F 011 ow s Pixge

3

4

4

6

6

6

Summary of Data on Hydrolysis Studies on "Pre-Sintered 6 Zirconium Dioxide - Phosphoric Acid Mixture with Phosphoric Acid and I t Zeolon H" Sintered at Various Temperatures

SM-46221-Q1 ... 111

% 1 . 0 SUMMATION AND CONCLUSION ~ ~

This project is a continuation of NASA Contract NAS 7-150, the purpose

of which i s to develop an inorganic ion exchange membrane for a hydrogen-

oxygen fuel cell capable of performing continuously for 300 hours o r greater

a t 0.5 volts and current densities of 25-50 ma/cm . This report covers the

progress made during the f i rs t quarter of the current project.

2

(1) Efforts to produce improved zirconium dioxide-phosphoric acid - "Zeolon H" fuel cell membranes were continued. A systematic investigation

of processing parameters was started and up to this date, membranes having

t ransverse strengths a s high as 5,000 - 6,000 psi and most recently a t the

7,500 psi level, have been made.

be used in future fuel cell tests.

Only membranes of 5,000 psi o r greater will

(2) The results of fuel cell t es t s involving the use of these membranes

demonstrated that performance was directly related to their t ransverse strengths,

i . e . , when the 5,000 psi plateau is reached, markedly improved fuel cell per -

formance is observed.

(3) A fuel cell was operated continuously for over 465 hours at 62OC and 2 a t 0 .5 volts and current densities ranging from 17 to 38 ma /cm .

tes ts a t higher temperature, current densities of 40 ma /cm

69OC and 15-35 ma /cm

In other 2 were achieved at

2 0 were achieved in the 80° - 90 C range, a l l at 0.5 volts.

Two additional laboratory scale fuel cells were constructed in

order to permit the study of electrolyte -catalyst combinations.

(4) Reconfirmation of the relationship between sintering temperature

and resistivity was obtained. In accordance with previous observations, final

sintering in the 300° - 5OO0C temperature range has little effect on resistivity

but a significant increase in resistivity occurs at sintering temperatures of

80OoC.

(5) It was found that hydrolytic stability of the membrane increases

with increasing final sintering temperature; however, hydrolytic stability in

itself, does not appear to be critically related to membrane performance in a

fuel cell.

(6) The program plan for the second quater is given.

SM-46221 -Q1 1

INTRODUCTION

The goal of this program is the development of an inorganic ion exchange

membrane for use in a hydrogen-oxygen fuel cell capable of operating at current

densities of 25-50 ma /cm

cant degree, the feasibility of these goals have been illustrated during the pre-

vious year of the program. During that period, current densities of 63 ma /cm

a t 0.5V and 65OC and 53 ma /cm

2 continuously f o r at least 300 hours. To a signifi-

2 2

at 0.5V and 9OoC were attained.

Further corroboration has been obtained during the las t quarter of the

present program in that a fuel cell life tes t has already exceeded the 300 hour

mark.

Although the maximum membrane strength attained last year was 5,000

psi in the t ransverse direction, it was felt that by proper choice of fabrication

techniques and guided by structure-property correlations, strengths of 8,000 - 10,000 psi could be achieved.

single membrane of 7,400 psi was obtained and several membranes with over

7,000 psi were produced.

to be related and an electrolytic membrane of such strength would be the key

to the attainment of the target fuel cell performance.

would be augmented further by the most appropriate choice of catalyst and

electrodes, a s well as the fuel cell design based on a through analysis of the

heat and mass transfer characterist ics.

It should be noted that in this f i r s t quarter a

Membrane strength and fuel cell performance appear

Of course, this effort

The most immediate objectives of the program had been the continua-

tion of improved membrane development and fuel cell life tes ts .

3 . 0 EXPERIMENTAL PROCEDURE. RESULTS AND DISCUSSION

c

~~~

The experimental effort has consisted of membrane composition and

fabrication studies and fuel cell evaluation.

constructed and placed into operation.

formed and hydrolysis stability evaluations on experimental membranes were

initiated.

Two new fuel cells were designed,

Resistivity measurements were per -

Literature and theoretical studies on catalysis and electrode mech-

anisms were

3.1

also initiated.

Membrane Composition and Fabrication Studies

NAS 7-150(1)

It was demonstratdd at A stropower Laboratory under contract

that inorganic membranes made in the following fashion

SM-46221 -Q1 2

, manifested t ransverse strengths a s high a s 5,000 psi and possessed appro-

priately high conductance levels:

1:l mixture of zirconium dioxide and phosphoric

acid was sintered.

state, the sintered mixture was mixed with equal

parts by weight of phosphoric acid and “Zeolon H.”

Then the final mixture was sintered.

After being ground to a fine

It is important to extablish the optimum fabrication temperatures during these

studies both for pre-sintering of the initial 1:l zirconium dioxide -phosphoric

acid mixture, a s well as that a t which the composite three component mixture

should be sintered. According to our previous results, thermal treatment affected membrane mechanical properties and behavior significantly. (1)

Our experience had dictated that the most useful results could

be obtained at pre-sintering temperatures ranging from 200° to 8OO0C and sin-

tering temperatures in the range of 300° to 80OOC.

performed: A 1:l mixture ratio of TAM C. p. Z r 0 2 and H3P04 was prepared

and sintered at temperature levels of 2OO0C and 60OoC. The sintered

materials were crushed and ground to minus 80 mesh and mixed with equal

par ts of H3P04 and “Zeolon H.” 13OoC and then granulated to minus 32 plus 80 mesh.

a t l5tms load into 2-inch diameter membranes having a thickness of the order

of 0. 7 mm. Finally, they were sintered at temperatures of 300°, 5OO0C and-800°C for two hours.

were determined and to date, have been evaluated in the Astropower fuel cell

under different thermal conditions. The resistivities of all membranes were

measured at elevated temperatures and humidities in the specialized equip-

ment designed for this purpose and described in Reference 1.

The following study was

These mixtures were dried for 16 hours at

Next, they were pressed

The tensile strengths of these resulting membranes

Transverse strengths of the membranes formulated a r e listed

in Table I.

is 3300-5400 psi. The trend is consistent with previous findings , i. e . ,

bonds contributing to higher structural strengths a r e formed a t higher t em-

peratures provided that active sites a r e not consumed in pr ior lower temper-

a ture treatments which lead to weaker s t ructural bond formation.

The range of transverse strengths obtained under these conditions (1)

In addition,

SM-46221 -Q1 3

TABLE I

.

TRANSVERSE STRENGTHS IN PSI OF P R E -SINTERED Z : :(CONIUM DIOXIDE - --

PHOSPHORIC ACID- - "ZEOLON-H!' MEMBRANES

(Sample Identification: 194-003, -A, -B, -C, and -D)

Siptering Temperature, OC 3 00

(A) Pre-Sintered

at ZOOOC 3315

(B) Pre-Sintered

at 4OO0C 5370

(C) Pre-Sintered

at 6OO0C 4455

(D) Pre-Sintered

at 8OO0C

500 -

5157

36 58

4773

4069

8 0 0 -

5350

3310

3600

3663

SM-46221 -Ql

Pre-sintering Composition -- - -- - H3P04 - 2 - - z rC>

-4 7 0% 3 0% €3 6 0 4 0 2, 40 6 0 E 30 7 0

Mix in Waricg Biender, d r y a t 12O”C, c r u s h ar.d screen to - 3 2 mesh .

“ - % i r c u a 9 , Calcia Stabilized Zirconia

P r e - b i ii t e r ing ‘r e nip e rat u r e llll_l

A 200Oc D 6OO0C

Crush and screen to -32 mesh

MEMBRANE COMPOSLT IONS

P r e - s intered 14ateriai

A

A

A

A

A

A

I3

I3

H

B

B

H

n D

13

r) n

c

13

Shf--16221 -Q1

pre-s intered Temperature

20o0c

Membrane Comp.

3.lembrane Sintering Temp.

1 . OA/ 1, 0 H3F’04/

1. 0 Zeolon H

1. OA/ 1. 0 €sjE‘Oq/

1. 0 Z,eolc;n I I

3 00°C

50OOC

800°C

30OOC

5 o o o c

80O0C

3OOoC

500°C

800°C

3OO0C

5OO0C

8OO0C

3 00OC

50o0c

8 O O k

3oooc 500°C

800°C

0 as previously found, sintering temperatures higher than 500 C have deleterious

effects on transverse strengths; apparently, bonds formed a t the higher

pre-sintering temperature a re being ruptured at the higher sintering tempera-

tures.

much more than 500 C a re favorable operating temperatures.

situation could change fo r different mixture ratios, as well as with incorporation

of water-balancing agents, other t'Mn "Zeolon H. ' I This matter will be ex-

plored further as the program i s continued. Other pertinent variables a r e ,

zirconium dioxide particle sizes and distribution, and the relative ratios of

zirconium dioxide to phosphoric acid binder to water -balancing agent.

0 It appears that pre-sintering a t less than 500 C and sintering at not 0 However, the

During the latter portion of this report period, a plan was

devised whereby the mixture ratios were varied in addition to the variations

of pre -sintering and sintering temperature.

compositions were involved.

membranes a re being prepared and their evaluations have been initiated.

Twenty-four membrane

The scheme is summarized in Table 11. These

3.2 Fuel Cell Evaluation ~~

The fuel cells used were of two basic constructions given in

Figures 1 and 2.

previously('!

in Figure 2 .

and shorten assembly time.

The electrodes used were the Teflon-platinum black-tantalum screen

configurations obtained from American Cyanamid.

constant a t 20.2 cm

six different evaluations a re summarized in Table III.

corresponding transverse strengths reported in Table I. cance a r e the results obtained f o r the 194-003B membrane (pre-sintered

at 40OoC) and sintered a t 3OO0C and for the 194-003A membrane (pre-

sintered at 20OoC) and sintered at 5OO0C, Tests 5 and 6 respectively. Test

5 was in operation a t 0. 5 volts for over 465 hours continuously.

nearly all of this time, the current density has been above 20 ma/cm2 and 2 has not dropped below 17.6 ma/cm , Plots of current density versus fuel

cell life for both tests a r e given in Figure 3 and Figure 4.

The cell shown in Figure 1 i s the same a s that described

Two cells were constructed in accordance with the features

This particular cell was designed to simplify the configuration

It contains fewer parts and i s more compact.

The electrode a rea was 2 and the catalyst was platinum black. The results of

Included a re the

Of most signifi-

During

The periodic

4

.

TABLE I1 (CONT'D)

P r e - sintered Material

Pre- sintering T emD eratur e

E

E

E

E

E

E

2oooc1

2oooc 20oOc

6OO0C

6OO0C

6OO0C

Membrane Comp.

l.OA/l. 0 H 3 P 0 4 i

1. 0 Zeolon H

1. OA/1. 0 H 3 P 0 4 /

1. 0 Zeolon H

Membrane Sintering Temp.

3OO0C

5OO0C

8OO0C

3OO0C

5OO0C

8OO0C

r

0 m m m

In

W W

M c- In

0

W W

4

d

In

w - 0 I I .

m * IC * m 9 *

W N

I C m a Q ' N"

o m m r ) N N G W

N

o m o o o o I n W O r n V 9 N I C r n - m m a r n a 0-00000 . . . . . . .

00 1 0 0 0 1 I I - o m I +

;d.lo

000 I L n m m I 01-m I

OIn M m

00

rnm . .

rna m 4 N N . .

000 I 09- I g \ w m I

000 I . . . I . . . I

000 I 4 . I

- a o I - I C - l w N m r n m " 7 . . . . . . . 4 4 - 4 - 4 4

-99 I NNrcl I . . . I - 4 4 1

* e I O m a la . . I *

4 4 I 4

~ _ ' t

o m 4 m g\NCOm

Q ' w c - m N N N Y

. . . . a E cpl

0000 000

999

. . . 4 4 4

0000

9999

. . . . 4 4 - 4

0000 . . . . M 4 - M

a 9 9 9

0000

9999

. . . . - 4 - 4

. . . . m a m m m m a o l n

a OD

H U

In 9

.O

M 9

0

a * 0

0 0 m 4 m 0 0 * QI 4

N

0 0 m

0 0 In I

5 0 0 I

.d. rn - 9

I

W 0 0

1 * rn

a

rl

In

c

4 d

a, u a, 7

x k 0 rd k 0 P

4

cr

4 2

b?

1 M

I

4

ld W

a ?

rn M c -d

d 0

L

a, a, k

5 a cj

+ u rn

\ a

a 3

L J

b z

I I

0 0 0 0 0 m rF pr) N d

0 0 Wl

0 b N

0 * N

0

N 4

0 a3 4

0 In 4

0 N 4

3 3\

0 9

0 IC)

9 c, l-d e,

.d : E

0 E Q) k

$ u

rF

Id a a, k a, 0 E

c,

9 a, k

pc

2

E

a

l-d k P

J pr) 0 0

I rF m 4

0 0

I I

0 0 m * , 0

I cu 4

0

extremes obtained in Test 6 a re of interest and this effect is being investigated

further. Polarization curves f o r Tests 1, 3 , 4, 5 and 6 are given in Figures 5

through 9 inclusive.

Four other fuel cell evaluations were performed using membranes

having similar chemical compositions but fabricated by less optimum means , affording transverse strengths of less than 3,000 psi.

order o f 2 1 0 ma/cm

considered to be sufficiently significant to be included in Table III.

Current densities of the

The results were not 2 0 at 0. 5V and 60 C were obtained.

Evidently only zirconium phosphate membranes having trans-

verse strengths greater than 5 ,000 psi should be of any interest to this

program. It appears that membranes having transverse strengths in the

8 ,000 - 10,000 psi level would yield superior fuel cell operational level.

Current indications are that the preparation of such membranes should be

possible during the course of this program.

In order to correlate fuel cell performance systematically

with membrane composition and fabrication variables outlined above , fuel

cell experiments will be performed in the following manner. *

Initially, the test membrane is evaluated in the fuel cell a t

about 6OoC and a t a voltage level of 0. 5V until the current density decreases

to 15 ma/cm . least 200 hours , a duplicate membrane wil l be evaluated under the same

conditions at 75OC. operation will be repeated at 9OoC. Finally, the best systems will be

selected for fuel cell evaluation at about 100 C in thermal cycling experiments.

2 If this membrane exhibits appropriate performance for at

If a similar performance level is reached at 75OC, the

0

In accordance with the above , Tests 5 and 6 will be repeated

a t 75Oc.

3.3 Resistivity Measurements

The laboratory efforts were concentrated on the zirconium

dioxide -phosphoric acid-"Zeolon HI! system, the 194-003 ser ies described

above.

Ref. 1. Measurements were performed at 70 , 90° and 105OC for relative

humidities ranging f rom 26 to 83%.

The experimental procedure was the same as that described in 0

Test membranes were held between

SM-46221 -Q 1 5

0 0 0 &

c

0 0 0 0 m Y Id -a aJ & P)

c m -0 c Id

u

Y

..-I

0 0 0 N

Id -0 a k P)

c

c1

4 2

.r(

m I

Q)

a" - 4 cc) 0 0

* m I

4

0

a, c Id & D

z

E 3

0 0 0 0 6 co

y Y

u 3 In 9

I

-0 In

-0 cc)

c1 C

N k 1 u

-0

-0 4

0

c 2 . .

e E : V

c cd M

.d

k- 0 c U

k 0

b 4

a P) > k 7 u E: 0

rd N k Id

.d c,

.d

d

n" Ln 0 k

2l iz

0 0 0 4

0 0 6

L 0 0 03

7 0 0 (c

0 0 9

0 0 m

0 0 w

4 J

0 0 yr)

0 0 N

e, c Id k P E : V

c Id M k

.rl

0 c U

k O w

Id N

k td

.!A

4 no \d e, k

& .rl czr

0 0 Q.

/ 0 0 0 0 a; tc

0 ' 0 0 0 VI v

c 0 W

a, c ld k

u c Id M

.d

k O w m a, > k 3 u c 0

ld N k rd

.r( c,

...I

I 4

n" P a, k 3 M

b.i .r(

I. 5

id * ‘L1

U U H

a, d

,% i-i .. u?

v) a, 4

ic I

4 4

a, u a, 1 i

4

: E

id k D

3 U

LZ id SD k 0 r: k c

.r(

H

-4

m a, > k 1 u c d

3

cd N

k id 0

.d 4 2

.rl

4

a

Go

a, k 1 hm k .rl

0 0 0

0 0 Tr

0 0 N

u 3 0 0 N

-0 a; & aJ

C m

e,

.4

0 0 co

I I a a *

U U U

0)

Id 4

f? .. 9

v)

a, U

b I

4 4

a, u a, 7

0) c Id k P

4

;r

E s V

c Id M k 0 r: k 0

.d

U

+I

[o

a, > k 1

c 0

Id N k rd

u .d c)

.d

4

n" v

aJ k 1 M

.r(

k

0 C N

2 platinum electrodes having approximately 1.0 cm surface area. The mem-

brane electrode assembly was placed in a furnace maintained a t a selected

temperature.

accurately known moisture content.

means of an alternating current bridge circuit a t 1,000 cps.

Humidity was controlled by the flow of humidified nitrogen of

Membrane resistance was measured by

0 Average resistivity values a t 70 C are given in Table IV, at 9OoC in Table V and at 105OC in Table VI. What is most apparent from

this work is that resistivity values are unaffected, more o r less , by the

pre -sintering temperature of the zirconium dioxide -phosphoric acid mixture.

As for the final sintering temperature, on going from 300 C to 5OO0C, the

resistivity increases slightly; however, a s the sintering temperature increases

to 8OO0C, there a r e highly significant increases in resistivity ranging from

five to ten-fold.

be analyzed in continued fuel cell studies.

0

How these trends are related to fuel cell performance, will

3.4 Hydrolysis Studies

Membrane behavior during fuel cell operation may be influenced

to some extent by stability towards hydrolysis.

was initiated wherein two-inch test membranes were each immersed under

200 m l of distilled water, with agitation, a t temperatures of 25OC and 73OC. Immersion periods were for one-hour intervals.

interval, the aqueous phase was quantitatively transferred to a 250 m l

volumetric flask, diluted to volume and potentiometrically titrated against

0. 1N sodium hydroxide standard solution.

indicated that the acid being titrated was phosphoric.

by formation of a yellow precipitate in ammoniacal silver nitrate solution.

After each one-hour immersion period, the sample was re-immersed under

200 m l of distilled water and the same operation was repeated. Pr ior to

the f i rs t immersion, each membrane was dried in an oven at 120 C and

weighed so that the weight of phosphoric acid liberated could be computed

on a percentage by weight of original membrane basis.

An experimental program f

After each immersion

Prior gravimetric determinations

This was established

0

Results obtained to date on the 194-003 ser ies of membranes

a re summarized in Table VU. least two determinations and a re based on the total amount of phosphoric

The numbers represent averages of a t -.

6

T A B L E IV

e ENORGANIC MEMBRANE RESISTIVITY DATA IN OHM-CM ON "PRE -SINTERED" __--- ------ - ZIRCONIUM DIOXIDE -PHOSPHORIC ACID MIXTURES WITH PHOSPHORIC ACID AND - --- -

"ZEOLON-H" SINTERED AT VARIOUS TEMPERATURES.

(Sample Identification: 194-003-A, -B, -C and -D)

RESISTIVITIES at 7 O°C and RELATIVE HUMIDITY of 8 0%

Sintering Tempera ture , OC 300 500 - 800 - 3. 32 lo3

1. 36 lo3

2

2

2

2

4.97 x 10

5.53 x 10

4. 58 x 10

3 . 3 0 ~ 10

2 2

2

2

(A) Pre -Sintered at 200°C (B) Pre-Sin tered at 4OO0C

(C) Pre -Sintered at 6OO0C 3. e6 i o

3.44 x 10

4.53 x 10 3

3 4 . 7 5 x 10

5.11 x 10

(D) P r e -Sintered at 8OO0C 4 . 6 9 ~ 1 0 a

RESISTIVITIES at 70°C and RELATIVE HUMIDITY of 6470 . 3

3

3

3

3.28 x 10

4.22 x 10

4. l o x 10

1. 13 x 10

2

2

2

2

5.31 x 10

6.48 x 10

4. l o x 10

3. l o x 10

2

2

2

2

(A) Pre -Sintered at 200°C 3.23 x 10

3.97 x 10

3. 09 x 1 0

4.44 x 10

(B) Pre-Sin tered at 4OO0C

(D) Pre-Sin tered at 8OO0C

(C) P r e - S h t e r e d at 6OO0C

RESISTWITIES at 7OoC and RELATIVE HUMIDITY of 4070 3

3

3 3

4. 17 x 10

4. 18 x 10 7.90 x 10

1.42 x 10

2 2

2

2

5.48 x 10

6. 04 x 10

4.33 x 10

3.27 x 10

2 2

2

2

(A) P r e -Sintered at 200°C

(C) Pre-Sin tered at 600°C

3.57 x 10

4. 09 x 1 0 3.57 x 1 0

3.27 x 10

(B) P r e -Sintered at 4OO0C

(D) Pre-Sin tered at 800°C

SM-46221-Q1

TABLE V

INORGANIC MEMBRANE RESISTIVITY DATA IN OHM-CM

ZIRCONIUM DIOXIDE -PHOSPHORIC ACID MIXTURES WITH PHOSPHORIC ACID AND IN "PRE -SINTERED"

~


(Sample Identification: 194 - 003 -As -B -C and -D)

RESISTIVITIES A T 9OoC and RELATIVE HUMIDITY of 83%

800 - 500 - 300 Sintering Tempera ture , OC - 2 7.27 x 10 2 (A) Pre-Sin tered at 2OO0C 1.26 x 10 1 . 9 5 ~ 10 2

2

2

6.80 x 10

4.48 x 10

4. 06 x 10

2

2

2

(B) Pre-Sin tered at 4OO0C 1.56 x 10 2 . 3 0 ~ 10 (C) P r e -Sintered at 6OO0C 1.15 x 10 1 . 5 2 ~ 10 (D) P r e -Sintered at 800°C 2 . 0 5 ~ 10 2.22 x 10

RESISTIVITIES AT 9OoC and RELATIVE HUMIDITY of 6870 3 (A) P r e -Sintered at 2OO0C 2.02 x l o 2 2.83 x 10' 1.36 x 10

1.42 lo3 2

2

2

(B) Pre-Sin tered at 4OO0C 2 . 2 6 ~ 10 3 . 3 3 x 10 3

2 3.33 x 10

7. 06 x 10

(C) Pre-Sin tered at 6OO0C 1.77 x 10 2. 17 x 10

1 (D) P r e -Sintered at 800°C 2.86 x 10 1 . 9 8 ~ 10

RESISTIVITIES AT 9OoC and RELATIVE HUMIDITY of 4570 3 (A) Pre-Sintered at 2OO0C 3. 15 x 10' 5.31 x 10' 4 . 8 0 ~ 10 3

3

3

4 . 4 0 ~ 10

4.58 x 10

1.63 x 10

2

2

2

(B) Pre-Sin tered at 4OO0C 4 .15 x 10 4 . 5 7 x 10 (C) Pre-Sin tered at 6OO0C 3. 08 x 10 4 . 8 2 ~ 10

(D) Pre-Sin tered at 800°C 3.69 x 10 4. 08 x 10

RESISITIVITIES AT 9OoC and RELATIVE HUMIDITY of 2970 3 (A) Pre-Sintered at 2OO0C 3 . 7 0 ~ 10' 5 . 9 0 ~ 10' 5. 19 x 10 3 5.59 x 10 (B) Pre-Sintered at 4OO0C 4.78 x 10 5 . 8 8 ~ 10

6. l o x IO3 (C) Pre-Sintered at 6OO0C 3 . 5 0 ~ 10 5.28 x 10 3 1.67 x 10

2

2

2 (D) Pre-Sin tered at 8OO0C 5.39 x lo2 3.45 x 10

SM-46221421

TABLE V I

I INORGANIC MEMBRANE RESISTIVITY DATA I__I- I N OHM-CM ON "PRE - -SINTERED"

ZIRCONIUM DIOXIDE -PHOSPHORIC ACID MIXTURES WITH PHOSPHORIC ACID P


(Sample Identification: 191 -003 -A, -B, -C and -D)

RESISTSTIVSIiES at 105OC and RELATIVE HUMIDITY of 7370

8 00 2

- 5 00 - 300 Sintering Tempera ture , OC - (A) Pre -Sintered at 2OO0C 3 . 0 6 ~ 19 3. 19 x 10 3.51 x 1 0

2 2 2

(B) Pre-Sin tered at 4OO0C 2.80 x 10 2.97 x 10 3.59 x 10 (Cl) Pre -Sintered at 6OO0C 3.01 x 10 3. 08 x 10 4 .59 x 10 (D) Pre -Sir,tered at 8OO0C 2. 92 x 1 0 2 . 8 8 ~ 1 0 3. 06 x 10

RESISTIVITIES at 105OC and RELATIVE HUMIDITY of 58%

2 2

2 2

5.49 x 10

5. 07 x 1 0

1. 09 x 10

3. 19 x 10

2

2

2

2

1.32 x 10

1.52 x 10

0 . 9 6 ~ 10 0.95 x 10

2

2

2

2

I

(A) Pre -Sintered at 2OO0C


(C) Pre -Sintered at 6OO0C

(D) Pre-Sin tered a t 8OO0C

1.31 x 10

0.98 x 10 0 . 8 2 ~ 10

1. 07 x 10

RESISTIVITIES at 105OC and RELATIVE HUMIDITY of 4070

1.26 l o 3 2

2

2

2

2.78 x 10

2. 19 x 10 1.30 x 10

1.52 x 10

2

2

2

2

(A) Pre -Sintered at 2OO0C

(B) Pre-Sin tered at 4OO0C 2.11 x 10

1.99 x 10 1. 08 x 10

1.80 x 10

3

3

2

1.21 x 10

1.30 x 1 0

5.83 x 10

(C) Pre-Sin tered at 6OO0C (D) Pre-Sin tered at 8OO0C

RESISTIVITIES at 105OC and RELATIVE HUMIDITY of 2670

4. 62 lo3 2 4 .10 x 10 3

2 1 . 2 5 ~ 10 3

2 4.38 x 10

4.71 x 10 3 . 3 0 ~ 10

2

2

2

(A) P r e -Sintered at 2OO0C


(C) P r e -Sintered at 6OO0C (D) Pre-Sin tered at 800°C 4. 09 x 10 2 2.79 x l o 2 1.72 x 10

3. 07 x 10

4.31 x 10

3. 09 x 10 3

TABLEVII -

SUMMARY O F DATA ON HYDROLYSIS STUDIES ON "PRE-SINTERED Z i R - - CONIUM DIOXIDE - PHOSPHORIC ACID MIXTURE WITH PHOSPHORIC ACID AND TZEOLON INTERED AT VARIOUS -- TEMPERATURES- (194-003 - A , B and D)( a?

300 500 8 00 0 Sintering Tempera ture C

-Pre -Sintered at 2OO0C 18. 9(b) ( 1 1.4)") 8. 1 1.4( 0. 9 ) " )

P r e -Sintered at 4OO0C 20.3 - - 0.7

P r e -Sintered at 8OO0C 22.2 13. 5 0. 5( 0.4)")

(a) Expressed as total weight of phosphoric ac id extracted divided by original weight of membrane x 100.

(b) Total percentage of phosphoric ac id recovered a f te r immers ion under water fo r four days = 22.2.

(c) Total percentage of phosphoric ac id recovered a f te r immers ion ur,der water for two hours at ambient temperature .

SM-46221 -Q1

- ._

I

acid*obtained by the end of the second immersion period. (a ) . From Table VI1 i t is apparent that pre-sintering temperatures

have little i f any, significant effect on the extent of recovery of phosphoric

acid.

liberation of phosphoric acid.

membranes in water represents an exceedingly more drastic test for phos-

phoric acid in comparison to what is actually occurring during fuel cell

operation.

relative membrane quality.

exists of any phosphoric acid being present in the washings of the inner con-

tents of the fuel cell, a t the conclusion of each determination.

to explore this matter further by performing phosphate content determinations

before and after fuel cell performance.

However, final sintering temperature greatly influences the extent of

It i s recognized that direct immersion of

It is merely being offered as another yardstick for measuring

So far, it has been noted that little evidence

It is planned

3 . 5 Future Work fo r Second Quarter

( 1 ) Me m b r ane Improve me n t Study

The study of the effect of composition and fabrication

variables wil l be continued according to the prescribed program

plan. will be used for the pre-fuel cell evaluation of experimental membranes.

Transverse strength resistivity and hydrolysis measurements

(2) Fuel Cell Tests

Promising membranes wil l continue to be tested in

laboratory fuel cells in the manner described in this report.

is planned to have at least five cells operating continuously.

to improve the design of such cells will be continued.

It

Efforts

(3) It i s planned to investigate the effectiveness of platinum-

iridium alloys, palladium -silver alloys and nickel boride.

The possible advantages of deposition of catalyst on

the membrane by each of the following procedures wil l be explored

as well.

(a) P r i o r blank determinations indicated that the correction f o r carbon dioxide content was negligible.

SM-46221 -Q1 7

8 , . - I

r

a.

b. Application by vacuum deposition

c. Application by electrostat ic means

Application during the sintering process '

(4) Electrode Study

A l i terature search indicates that highly p rec i se ,

uniform electroformed wire m e s h is available down to hole s izes

of the o r d e r of microns. Meshes will be prepared f rom tantalum

coated with the above mentioned catalysts and impregnated with

hydrophobic ma te r i a l s such a s Teflon or silicones.

Catalysts and electrodes will be evaluated in the same

type of fuel cel ls described in this report , with the bes t types of

membranes obtained f rom this project being used simultaneously.

4 . 0 PROJECT PERSONNEL

The following Astropower Staff Members are connected with this

program at this time; Dr . C. Berger , Pr incipal Investigator, Dr . M. P.

S t r i e r , M r . F. C. Arrance , Mr. G. Belfort , M r . E. Feher and Mr. A.

G. Rosa. e,

REFERENCE:

1. "Investigation of Zeolite Membrane Electrolytes for Fuel Cells" NASA Contract NAS7-150, Final Report Astropower Inc . , Report 108F, March 1964.

SM-46221 -Q 1 8

inorganic ion exchange membrane fuel cell

Documents