A facility which produces electrodes for spacecraft power supplies is described. The electrode assembly procedures are discussed. A number of design features in the production process are reported including a batch operation mode and an independent equipment module design approach for transfering the electrode materials from process tank to process tank

Miller, L.

English

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AEROSPACE  ELECTRODE  LINE 
L.  Miller 
Eagle  Picher 
Let  me  just give you  a  little  bit of history  before I go  directly into my  paper. 
For  more  than 20 years  the Eagle  Picher  space-battery  operations  have  been  located  in our 
Joplin, Missouri plant,  and we  have  been  procuring  finished  electrodes  from  our  Colorado  Springs 
facility. We consider  this  facility to be  our  commercial  operation  or  high  volume  operation. 
As of  now,  and  at  least  starting  about  the  last 6 months, we now have  a  new  electrode  facility 
in  operation  in  our  Joplin  plant. We believe that  this  facility  may  be  the  first  electrode-processing 
nickel  cadmium  and  nickel  hydrogen  designed,  developed,  and  dedicated  solely  to  the  production  of 
electrodes  for  space-battery  systems. 
The facility  offers  production  capacity  for  not  only  the  chemical  electrodes  which  we  have 
been  using  for  a  great  deal  of  time  now,  but  also  the  newer  electrochemical  designs. 
(Figures 6- 1 5 and 6- 16) 
These  are  just a couple  of  vugraphs. I have  a  couple  of  more  to give you an  overview of  the 
system.  I  might  just  comment  on  the  production  capability  of  the  operation. 
Right  now,  we  are  not really running  at full capacity. We can produce  about 150 square  feet 
of  plaque  material  in  an  eight-hour  production  shift.  However,  the  design  of  the  equipment is such 
that  i t  is capable  of  handling  three  times  this  volume. 
There  are  a  number of unique design  features  that  are  specifically  incorporated to  produce  a 
high-quality electrode. We have made these changes based upon our experience as part of the 
operation. Also, we are indebted to the recommendations and suggestions of Jerry Halpert and 
Floyd  Ford. 
Let  me  go  through  a  couple  of  these  items  here. 
1 .  A batch  rather  than  a  continuous  operation  mode was selected  for  better  process  control. 
2. An  independent  equipment  module design approach was  taken to assure  process  solution 
isolation. In other words, electrode materials are themselves transferred from process tank to 
process  tank,  rather  than  the  much  easier  and  lower  cost  method of pumping in different  process 
solutions  into  the  same  tank. 
The  benefits  achieved  here  are  elimination  of  the  slow,  but  inevitable  buildup  of  tank,  plumb- 
ing,  and  solution  reservoir  contamination  associated  with  partial  solution  mixing. 
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https://ntrs.nasa.gov/search.jsp?R=19800012375 2020-03-21T18:19:23+00:00Z
3. All equipment,  even  including  the  exhaust  duct  work,  is  constructed of  stainless  steel  and 
all current  carrying  components  such  as  buss  bar  and  electrode  process  racks  are  constructed  of  pure 
nickel to prevent  contamination. 
4. Equipment design  was  easy  and  was  designed  for  easy  access to facilitate  both  internal  and 
external cleaning. 
5. Continuous  in-line  process  monitoring  and  an  analytical  chemical  laboratory  dedicated  to 
this  operation  assures  achievement  of  the  desired  high  degree  of  process  control. 
(Figures 6- 17  and 6- 1 8) 
6. Each  piece of 12  X 12  electrode  material  blank,  and  there  is  three  per  process  rack,  is 
connected  to  the  process  rack by four  redundant,  fusion  welded  nickel  tab  connections  to  ensure 
uniform  current  distribution  within  the parallel  rack  assembly. 
7. In addition,  each  rack  assembly  offers  an  adjustable  connection  to  the  process  tank  buss 
bar, allowing fine tuning of current flow t o  achieve uniform current distribution through each 
parallel  rack  assembly. 
8. During actual operation, process tank to reservoir solution recirculation provisions 
permitted  the  introduction of filtration  and  sedimentation  steps to maintain  ultra  high  solution 
purity levels. 
9. The  very  important, final electrode  material  formation  step,  a  unique high-voltage  system 
was devised featuring multiple, series-connected small formation cells, again assuring uniform 
current  distribution. 
That’s  what  you  could see on your right over  there if it  were  a  better  vugraph. 
I O .  Each of the  above  formation cells is fixtured so as to  permit  frequent  replacement  of  the 
electrolyte  solution  which,  of  course,  always is heavily contaminated i n  this  operation. 
1 1 .  A special multistep  cascade,  deionized  water  washing  technique  followed  by  a  vacuum  dryin 
step,  produces finished  electrode  materials  exhibiting  the  desired  physical  stability  and  cleanliness 
characteristics. 
12. A series step  deionizing  system  which  means  we  have  two  deionizers  connected  in  series 
so we  have  pretreatment as well as  final treatment to ensure  a  very  high  quality  deionized  water 
source  for all operations of the  system. 
In addition to the formation there, we have what we call our  final electrode carbonate 
treatment  equipment. Basically,  there  are  two  systems  in  operation  depending  on  the  customer’s 
preference. 
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One involves  a  multiflushing  of  the  finished  welded  cell,  and  the  other  involves  a  hot  caustic 
dip - it  can  be  boiling  caustic  -just  prior to final  cell  assembly  for  carbonate  reduction  purposes. 
With respect to the  results,  as I say,  we  have  only  been in operation  for six months. We don’t 
have  long-term  data,  but  some  of  the  initial  observations based upon  our  previous  source  of 
electrodes - we  used to  only use about  one-half  of  the  electrodes  that we procured.  The  attrition 
was either as a  result of out-of-weight  range  plaques, o r  physical  defects  associated  with  the 
electrode  materials. We now use more  than 90 percent  of  the  electrodes  produced. 
One  thing  that was somewhat  of  a  surprise to us  is that  generally  when  we  built  some  fresh 
cells,  we  needed,  through  a  series  of  bum-in  cycles, t o  develop  their  capacity,  or  at  least  stabilize 
their  capacity. 
We find now  that cells  built  with  electrodes  on  this  new  line  exhibit  a  long-term  capacity 
from  the  very  first  cycle. 
One  of  our  observations is that  the  activity  in  the  electrode  appears  to have  been  improved to  
the  point  that we can operate  a cell  design to  15 to  20 percent  more  electrolyte  and still  measure 
lower  internal  pressures on cycling. 
DISCUSSION 
FORD: Lee, I don’t  remember  you  commenting on making  the  plaques  themselves.  Are  you 
making  those  in  Joplin? 
MILLER:  At  this  time  the  raw  sinter is still made in our Colorado  Springs  facility.  There  are 
plans to set LIP a  new  operation  at  Joplin  for  that,  also. 
FORD: Will you be automated  with  that,  or  are you  going  to use the  old  magnet  technique? 
MILLER:  It is rather  a  tough  decision  right  now.  The  dry  sinter or  the  individual  sintering 
process  has  certain  advantages;  the  continuous or  automated  slurry  has its own  advantages. I would 
say  right now  the  preference  would  be  to  probably  go  to  the  continuous  slurry  process. 
GROSS: Lee, you indicated  that it was determined  that  the  batched  process  would  be  better 
than  the  continuous  process. 
Offhand, I would have guessed the other way around. Can you explain that a little bit 
further, please? 
MILLER: Well, the  batch  process  just  lets  you  step  into  the  middle  of  the  process  and  make 
measurements  more  easily  than  a  continuous  process  because  it will be  better  control. 
GROSS: The other point was, I have always felt that the electrochemical impregnation 
method  had  the  potential  to  be  a  completely closed system,  to  be closed  off  from  the  atmosphere, 
and  solved  once  and  for all the  problem  of  carbonates  getting  on  the  plates. 
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Apparently,  you  elected  not  to  do  that,  or  couldn’t,  and I wondered  if  you  would  explain 
why that  happened. 
MILLER:  I am not sure  what  you  mean  by  that,  Sid.  There is a  great  deal  of gas evolution 
associated  with the  electrochemical process, more so than  the  chemical process. 
GROSS: Yes, evolution. Would that mean gas would  go out  and  you  could have gas evolve 
without allowing atmospheric gases to get  in? 
MILLER: Maybe  I  don’t understand  your  question. What do  you mean by a closed system? 
GROSS: Closed from  the  atmosphere,  from  the  contamination  of  carbon  dioxide  and gas, 
which produces  carbonates on the  plates  during  manufacture. 
MILLER:  One  thing  you can do with  the  electrochemical  process  though is to  finish the 
impregnation  step in the acid state, so you  don’t  have to  be  as  careful  as in the chemical  process 
with  respect to  storage of plaques  between  operations. 
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Figure 6- 1 5 Figure 6- 16 
Figure 6- 17 Figure 6- 18 


Aerospace electrode line

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