<s>
A	O
nickel	B-Algorithm
–	I-Algorithm
hydrogen	I-Algorithm
battery	I-Algorithm
(	O
NiH2	O
or	O
Ni	O
–	O
H2	O
)	O
is	O
a	O
rechargeable	B-Architecture
electrochemical	O
power	O
source	O
based	O
on	O
nickel	O
and	O
hydrogen	O
.	O
</s>
<s>
It	O
differs	O
from	O
a	O
nickel	B-Device
–	I-Device
metal	I-Device
hydride	I-Device
(	O
NiMH	B-Device
)	O
battery	O
by	O
the	O
use	O
of	O
hydrogen	O
in	O
gaseous	O
form	O
,	O
stored	O
in	O
a	O
pressurized	O
cell	O
at	O
up	O
to	O
1200psi	O
(	O
82.7bar	O
)	O
pressure	O
.	O
</s>
<s>
The	O
nickel	B-Algorithm
–	I-Algorithm
hydrogen	I-Algorithm
battery	I-Algorithm
was	O
patented	O
on	O
February	O
25	O
,	O
1971	O
by	O
Alexandr	O
Ilich	O
Kloss	O
and	O
Boris	O
Ioselevich	O
Tsenter	O
in	O
the	O
United	O
States	O
.	O
</s>
<s>
NiH2	O
cells	O
using	O
26%	O
potassium	O
hydroxide	O
(	O
KOH	O
)	O
as	O
an	O
electrolyte	O
have	O
shown	O
a	O
service	O
life	O
of	O
15	O
years	O
or	O
more	O
at	O
80%	O
depth	B-Algorithm
of	I-Algorithm
discharge	I-Algorithm
(	O
DOD	O
)	O
The	O
energy	O
density	O
is	O
75Wh/kg	O
,	O
60Wh/dm3	O
specific	O
power	O
220W/kg	O
.	O
</s>
<s>
While	O
the	O
energy	O
density	O
is	O
only	O
around	O
one	O
third	O
as	O
that	O
of	O
a	O
lithium	O
battery	O
,	O
the	O
distinctive	O
virtue	O
of	O
the	O
nickel	B-Algorithm
–	I-Algorithm
hydrogen	I-Algorithm
battery	I-Algorithm
is	O
its	O
long	O
life	O
:	O
the	O
cells	O
handle	O
more	O
than	O
20,000	O
charge	B-Algorithm
cycles	I-Algorithm
with	O
85%	O
energy	O
efficiency	O
and	O
100%	O
faradaic	O
efficiency	O
.	O
</s>
<s>
NiH2	O
rechargeable	B-Architecture
batteries	I-Architecture
possess	O
properties	O
which	O
make	O
them	O
attractive	O
for	O
the	O
energy	O
storage	O
of	O
electrical	O
energy	O
in	O
satellites	O
and	O
space	O
probes	O
.	O
</s>
<s>
For	O
example	O
,	O
the	O
ISS	O
,	O
Mercury	O
Messenger	O
,	O
Mars	O
Odyssey	O
and	O
the	O
Mars	O
Global	O
Surveyor	O
are	O
equipped	O
with	O
nickel	B-Algorithm
–	I-Algorithm
hydrogen	I-Algorithm
batteries	I-Algorithm
.	O
</s>
<s>
The	O
Hubble	O
Space	O
Telescope	O
,	O
when	O
its	O
original	O
batteries	O
were	O
changed	O
in	O
May	O
2009	O
more	O
than	O
19	O
years	O
after	O
launch	O
,	O
led	O
with	O
the	O
highest	O
number	O
of	O
charge	B-Algorithm
and	I-Algorithm
discharge	I-Algorithm
cycles	I-Algorithm
of	O
any	O
NiH2	O
battery	O
in	O
low	O
Earth	O
orbit	O
.	O
</s>
<s>
The	O
development	O
of	O
the	O
nickel	B-Algorithm
hydrogen	I-Algorithm
battery	I-Algorithm
started	O
in	O
1970	O
at	O
Comsat	O
and	O
was	O
used	O
for	O
the	O
first	O
time	O
in	O
1977	O
aboard	O
the	O
U.S.	O
Navy	O
's	O
Navigation	O
technology	O
satellite-2	O
(	O
NTS-2	O
)	O
.	O
</s>
<s>
Currently	O
,	O
the	O
major	O
manufacturers	O
of	O
nickel-hydrogen	B-Algorithm
batteries	I-Algorithm
are	O
Eagle-Picher	O
Technologies	O
and	O
Johnson	O
Controls	O
,	O
Inc	O
.	O
</s>
<s>
The	O
nickel-hydrogen	B-Algorithm
battery	I-Algorithm
combines	O
the	O
positive	O
nickel	O
electrode	O
of	O
a	O
nickel-cadmium	O
battery	O
and	O
the	O
negative	O
electrode	O
,	O
including	O
the	O
catalyst	B-Device
and	O
gas	O
diffusion	O
elements	O
,	O
of	O
a	O
fuel	O
cell	O
.	O
</s>
<s>
Compared	O
with	O
other	O
rechargeable	B-Architecture
batteries	I-Architecture
,	O
a	O
nickel-hydrogen	B-Algorithm
battery	I-Algorithm
provides	O
good	O
specific	O
energy	O
of	O
55-60watt-hours/kg	O
,	O
and	O
very	O
long	O
cycle	B-Algorithm
life	I-Algorithm
(	O
40,000	O
cycles	O
at	O
40%	O
DOD	O
)	O
and	O
operating	O
life	O
(	O
>	O
15	O
years	O
)	O
in	O
satellite	O
applications	O
.	O
</s>
<s>
The	O
negative	O
hydrogen	O
electrode	O
utilises	O
a	O
teflon-bonded	O
platinum	O
black	O
catalyst	B-Device
at	O
a	O
loading	O
of	O
7mg/cm2	O
and	O
the	O
separator	O
is	O
knit	O
zirconia	O
cloth	O
(	O
ZYK-15	O
Zircar	O
)	O
.	O
</s>
