Automotive Engineering - March 2023 - BET31

sodium-aluminum battery design has the
advantage of being inexpensive and easy
to produce in the United States from much
A Cathode
+
Molten salt
A
Aluminum wool
B
C
D
-
B
C
D
Sodium ions
Solid-state electrolyte
Sodium anode
The new sodium-aluminum battery design allows only sodium (depicted as yellow balls) to
move through the solid-state electrolyte to charge the battery. Being constructed of inexpensive
Earth-abundant materials such as sodium salts and aluminum wool, a scrap product of
aluminum manufacturing, is an advantage. (Image: Sara Levine, PNNL)
more abundant materials.
" With optimization, we expect the specific
energy density and the life cycle could
reach even higher and longer, " added Li.
PNNL scientists collaborated with colleagues
at the U.S.-based Nexceris to
assemble and test the battery. Nexceris,
through their new business Adena Power,
supplied their patented solid-state, sodium-based
electrolyte to PNNL to test
the battery's performance. This crucial
battery component allows the sodium
ions to travel from the negative (anode)
to the positive (cathode) side of the battery
as it charges.
" Our primary goal for this technology is
to enable low-cost, daily shifting of solar
energy into the electrical grid over a 10- to
24-hour period, " said Vince Sprenkle, a
PNNL battery technology expert with more
than 30 patented designs for energy storage
systems and associated technology.
" This is a sweet spot where we can start to
think about integrating higher levels of renewables
into the electrical grid to provide
true grid resiliency from renewable resources
such as wind and solar power. "
Sprenkle was part of the team that deResearch
teams at Pacific Northwest National Laboratory study how to integrate a utility-scale solar
energy and battery storage facility into the grid at a facility near its Richland, WA, headquarters.
Here they monitor and analyze data to evaluate the financial benefits of storing renewable energy
and incorporating intermittent renewables onto the grid. (Image: Andrea Starr, PNNL)
neutral molten salt can undergo a further
reaction into an acidic molten salt. Crucially,
this second acidic reaction mechanism increases
the battery's capacity. Specifically,
after 345 charge/discharge cycles at high
current, this acidic reaction mechanism retained
82.8 percent of peak charge capacity.
The energy that a battery can deliver in
the discharge process is called its specific
Battery & Electrification Technology, March 2023
energy density, which is expressed as " watt
hour per kilogram " (Wh/kg). Although the
battery is in early-stage or " coin cell " testing,
the researchers speculate that it could
result in a practical energy density of up to
100 Wh/kg. In comparison, the energy density
for lithium-ion batteries used in commercial
electronics and electric vehicles is
around 170-250 Wh/kg. However, the new
veloped this battery's new flexible design,
which also shifted the battery from a traditional
tubular shape to a flat, scalable one
that can more easily be stacked and expanded
as the technology develops from
coin-sized batteries to a larger grid-scale
demonstration size. More importantly, this
flat cell design allows the cell capacity to
be increased by simply using a thicker
cathode, which the researchers leveraged
in this work to demonstrate a triple capacity
cell with sustained discharge of 28.2hours
under laboratory conditions.
Most current battery technologies, including
Li-ion batteries, are well suited for
short-term energy storage. To meet the
demand for 10-plus hours of energy storage
will require the development of new,
low-cost, safe, and long duration battery
concepts beyond current state-of-the-art
battery technologies. This research provides
a promising lab-scale demonstration
toward that goal.
For more information, contact Karyn
Hede at karyn.hede@pnnl.gov; 509375-2144.
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Automotive Engineering - March 2023

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