<s>
Molten-salt	B-Architecture
batteries	I-Architecture
are	O
a	O
class	O
of	O
battery	O
that	O
uses	O
molten	O
salts	O
as	O
an	O
electrolyte	O
and	O
offers	O
both	O
a	O
high	O
energy	O
density	O
and	O
a	O
high	O
power	O
density	O
.	O
</s>
<s>
Traditional	O
non-rechargeable	O
thermal	B-Architecture
batteries	I-Architecture
can	O
be	O
stored	O
in	O
their	O
solid	O
state	O
at	O
room	O
temperature	O
for	O
long	O
periods	O
of	O
time	O
before	O
being	O
activated	O
by	O
heating	O
.	O
</s>
<s>
Rechargeable	B-Architecture
liquid-metal	B-Architecture
batteries	I-Architecture
are	O
used	O
for	O
industrial	O
power	O
backup	O
,	O
special	O
electric	O
vehicles	O
and	O
for	O
grid	O
energy	O
storage	O
,	O
to	O
balance	O
out	O
intermittent	O
renewable	O
power	O
sources	O
such	O
as	O
solar	O
panels	O
and	O
wind	O
turbines	O
.	O
</s>
<s>
Thermal	B-Architecture
batteries	I-Architecture
originated	O
during	O
World	O
War	O
II	O
when	O
German	O
scientist	O
Georg	O
Otto	O
Erb	O
developed	O
the	O
first	O
practical	O
cells	O
using	O
a	O
salt	O
mixture	O
as	O
an	O
electrolyte	O
.	O
</s>
<s>
Since	O
the	O
mid-1960s	O
much	O
development	O
work	O
has	O
been	O
undertaken	O
on	O
rechargeable	B-Architecture
batteries	I-Architecture
using	O
sodium	O
(	O
Na	O
)	O
for	O
the	O
negative	O
electrodes	O
.	O
</s>
<s>
The	O
sodium	B-Architecture
–	I-Architecture
sulfur	I-Architecture
battery	I-Architecture
(	O
NaS	B-Architecture
battery	I-Architecture
)	O
,	O
along	O
with	O
the	O
related	O
lithium	B-Algorithm
–	I-Algorithm
sulfur	I-Algorithm
battery	I-Algorithm
employs	O
cheap	O
and	O
abundant	O
electrode	O
materials	O
.	O
</s>
<s>
It	O
used	O
liquid	O
sulfur	O
for	O
the	O
positive	O
electrode	O
and	O
a	O
ceramic	O
tube	O
of	O
beta-alumina	B-Algorithm
solid	I-Algorithm
electrolyte	I-Algorithm
(	O
BASE	O
)	O
.	O
</s>
<s>
Insulator	O
corrosion	O
was	O
a	O
problem	O
because	O
they	O
gradually	O
became	O
conductive	O
,	O
and	O
the	O
self-discharge	B-Algorithm
rate	O
increased	O
.	O
</s>
<s>
Because	O
of	O
their	O
high	O
specific	O
power	O
,	O
NaS	B-Architecture
batteries	I-Architecture
have	O
been	O
proposed	O
for	O
space	O
applications	O
.	O
</s>
<s>
An	O
NaS	B-Architecture
battery	I-Architecture
for	O
space	O
use	O
was	O
successfully	O
tested	O
on	O
the	O
Space	O
Shuttle	O
mission	O
STS-87	O
in	O
1997	O
,	O
but	O
the	O
batteries	O
have	O
not	O
been	O
used	O
operationally	O
in	O
space	O
.	O
</s>
<s>
NaS	B-Architecture
batteries	I-Architecture
have	O
been	O
proposed	O
for	O
use	O
in	O
the	O
high-temperature	O
environment	O
of	O
Venus	B-Application
.	O
</s>
<s>
A	O
consortium	O
formed	O
by	O
Tokyo	O
Electric	O
Power	O
Co	O
.	O
(	O
TEPCO	O
)	O
and	O
NGK	O
Insulators	O
Ltd	O
.	O
declared	O
their	O
interest	O
in	O
researching	O
the	O
NaS	B-Architecture
battery	I-Architecture
in	O
1983	O
,	O
and	O
became	O
the	O
primary	O
drivers	O
behind	O
the	O
development	O
of	O
this	O
type	O
ever	O
since	O
.	O
</s>
<s>
TEPCO	O
chose	O
the	O
NaS	B-Architecture
battery	I-Architecture
because	O
its	O
component	O
elements	O
(	O
sodium	O
,	O
sulfur	O
and	O
ceramics	O
)	O
are	O
abundant	O
in	O
Japan	O
.	O
</s>
<s>
The	O
commercial	O
NaS	B-Architecture
battery	I-Architecture
bank	O
offers	O
:	O
</s>
<s>
A	O
lower-temperature	O
variant	O
of	O
molten-salt	B-Architecture
batteries	I-Architecture
was	O
the	O
development	O
of	O
the	O
ZEBRA	O
(	O
originally	O
,	O
"	O
Zeolite	O
Battery	O
Research	O
Africa	O
"	O
;	O
later	O
,	O
the	O
"	O
Zero	O
Emissions	O
Batteries	O
Research	O
Activity	O
"	O
)	O
battery	O
in	O
1985	O
,	O
originally	O
developed	O
for	O
electric	O
vehicle	O
applications	O
.	O
</s>
<s>
Since	O
both	O
and	O
Na	O
are	O
liquid	O
at	O
the	O
operating	O
temperature	O
,	O
a	O
sodium-conducting	O
β-alumina	B-Algorithm
ceramic	I-Algorithm
is	O
used	O
to	O
separate	O
the	O
liquid	O
sodium	O
from	O
the	O
molten	O
.	O
</s>
<s>
The	O
primary	O
elements	O
used	O
in	O
the	O
manufacture	O
of	O
these	O
batteries	O
have	O
much	O
higher	O
worldwide	O
reserves	O
and	O
annual	O
production	O
than	O
lithium	B-Language
.	O
</s>
<s>
For	O
comparison	O
,	O
LiFePO4	O
lithium	B-Language
iron	O
phosphate	O
batteries	O
store	O
90	O
–	O
110Wh/kg	O
,	O
and	O
the	O
more	O
common	O
LiCoO2	O
lithium-ion	O
batteries	O
store	O
150	O
–	O
200Wh/kg	O
.	O
</s>
<s>
A	O
nano	O
lithium-titanate	B-Algorithm
battery	I-Algorithm
stores	O
72Wh/kg	O
and	O
can	O
provide	O
power	O
of	O
760W/kg	O
.	O
</s>
<s>
The	O
company	O
claimed	O
that	O
the	O
battery	O
required	O
half	O
the	O
volume	O
of	O
lithium-ion	O
batteries	O
and	O
one	O
quarter	O
that	O
of	O
sodium	B-Architecture
–	I-Architecture
sulfur	I-Architecture
batteries	I-Architecture
.	O
</s>
<s>
Innovenergy	O
in	O
Meiringen	O
,	O
Switzerland	B-Protocol
has	O
further	O
optimised	O
this	O
technology	O
with	O
the	O
use	O
of	O
domestically	O
sourced	O
raw	O
materials	O
,	O
except	O
for	O
the	O
nickel	O
powder	O
component	O
.	O
</s>
<s>
Despite	O
the	O
reduced	O
capacity	O
compared	O
with	O
lithium-ion	O
batteries	O
,	O
the	O
ZEBRA	O
technology	O
is	O
applicable	O
for	O
stationary	O
energy	O
storage	O
from	O
solar	O
power	O
.	O
</s>
<s>
Professor	O
Donald	O
Sadoway	O
at	O
the	O
Massachusetts	O
Institute	O
of	O
Technology	O
has	O
pioneered	O
the	O
research	O
of	O
liquid-metal	O
rechargeable	B-Architecture
batteries	I-Architecture
,	O
using	O
both	O
magnesium	O
–	O
antimony	O
and	O
more	O
recently	O
lead	O
–	O
antimony	O
.	O
</s>
<s>
In	O
2011	O
,	O
the	O
researchers	O
demonstrated	O
a	O
cell	O
with	O
a	O
lithium	B-Language
anode	O
and	O
a	O
lead	O
–	O
antimony	O
cathode	O
,	O
which	O
had	O
higher	O
ionic	O
conductivity	O
and	O
lower	O
melting	O
points	O
(	O
350	O
–	O
430°C	O
)	O
.	O
</s>
<s>
In	O
September	O
2014	O
,	O
a	O
study	O
described	O
an	O
arrangement	O
using	O
a	O
molten	O
alloy	O
of	O
lead	O
and	O
antimony	O
for	O
the	O
positive	O
electrode	O
,	O
liquid	O
lithium	B-Language
for	O
the	O
negative	O
electrode	O
;	O
and	O
a	O
molten	O
mixture	O
of	O
lithium	B-Language
salts	O
as	O
the	O
electrolyte	O
.	O
</s>
<s>
A	O
recent	O
innovation	O
is	O
the	O
PbBi	O
alloy	O
which	O
enables	O
lower	O
melting	O
point	O
lithium-based	O
battery	O
.	O
</s>
<s>
Ionic	O
liquids	O
have	O
been	O
shown	O
to	O
have	O
prowess	O
for	O
use	O
in	O
rechargeable	B-Architecture
batteries	I-Architecture
.	O
</s>
<s>
Thermal	B-Architecture
batteries	I-Architecture
use	O
an	O
electrolyte	O
that	O
is	O
solid	O
and	O
inactive	O
at	O
ambient	O
temperatures	O
.	O
</s>
<s>
The	O
high	O
power	O
is	O
due	O
to	O
the	O
high	O
ionic	O
conductivity	O
of	O
the	O
molten	O
salt	O
(	O
resulting	O
in	O
a	O
low	O
internal	O
resistance	O
)	O
,	O
which	O
is	O
three	O
orders	O
of	O
magnitude	O
(	O
or	O
more	O
)	O
greater	O
than	O
that	O
of	O
the	O
sulfuric	O
acid	O
in	O
a	O
lead	B-Device
–	I-Device
acid	I-Device
car	I-Device
battery	I-Device
.	O
</s>
<s>
This	O
property	O
of	O
unactivated	O
storage	O
has	O
the	O
double	O
benefit	O
of	O
avoiding	O
deterioration	O
of	O
the	O
active	O
materials	O
during	O
storage	O
and	O
eliminating	O
capacity	O
loss	O
due	O
to	O
self-discharge	B-Algorithm
until	O
the	O
battery	O
is	O
activated	O
.	O
</s>
<s>
In	O
the	O
1980s	O
lithium-alloy	O
anodes	O
replaced	O
calcium	O
or	O
magnesium	O
anodes	O
,	O
with	O
cathodes	O
of	O
calcium	O
chromate	O
,	O
vanadium	O
or	O
tungsten	O
oxides	O
.	O
</s>
<s>
Lithium	B-Language
–	O
silicon	O
alloys	O
are	O
favored	O
over	O
the	O
earlier	O
lithium	B-Language
–	O
aluminium	O
alloys	O
.	O
</s>
<s>
The	O
corresponding	O
cathode	O
for	O
use	O
with	O
the	O
lithium-alloy	O
anodes	O
is	O
mainly	O
iron	O
disulfide	O
(	O
pyrite	O
)	O
replaced	O
by	O
cobalt	O
disulfide	O
for	O
high-power	O
applications	O
.	O
</s>
<s>
The	O
electrolyte	O
is	O
normally	O
a	O
eutectic	O
mixture	O
of	O
lithium	B-Language
chloride	O
and	O
potassium	O
chloride	O
.	O
</s>
<s>
More	O
recently	O
,	O
other	O
lower-melting	O
,	O
eutectic	O
electrolytes	O
based	O
on	O
lithium	B-Language
bromide	O
,	O
potassium	O
bromide	O
,	O
and	O
lithium	B-Language
chloride	O
or	O
lithium	B-Language
fluoride	O
have	O
also	O
been	O
used	O
to	O
provide	O
longer	O
operational	O
lifetimes	O
;	O
they	O
are	O
also	O
better	O
conductors	O
.	O
</s>
<s>
The	O
so-called	O
"	O
all-lithium	O
"	O
electrolyte	O
based	O
on	O
lithium	B-Language
chloride	O
,	O
lithium	B-Language
bromide	O
,	O
and	O
lithium	B-Language
fluoride	O
(	O
no	O
potassium	O
salts	O
)	O
is	O
also	O
used	O
for	O
high-power	O
applications	O
,	O
because	O
of	O
its	O
high	O
ionic	O
conductivity	O
.	O
</s>
<s>
A	O
radioisotope	B-Application
thermal	I-Application
generator	I-Application
,	O
such	O
as	O
in	O
the	O
form	O
of	O
pellets	O
of	O
90SrTiO4	O
,	O
can	O
be	O
used	O
for	O
long-term	O
delivery	O
of	O
heat	O
for	O
the	O
battery	O
after	O
activation	O
,	O
keeping	O
it	O
in	O
a	O
molten	O
state	O
.	O
</s>
<s>
Thermal	B-Architecture
batteries	I-Architecture
are	O
used	O
almost	O
exclusively	O
for	O
military	O
applications	O
,	O
notably	O
for	O
nuclear	O
weapons	O
and	O
guided	O
missiles	O
.	O
</s>
