Automotive Engineering - March 2023 - BET30

Sodium-Ion Battery Anode for Energy Storage
Carbonaceous anodes based on organic pigments exhibit a high sodium-ion storage performance and
excellent cycle stability.
Pusan National University, Busan, South Korea
L
ithium-ion batteries have high energy
density and a long cycle life, making
them indispensable in portable electronics
as well as electric vehicles. However,
the high cost and limited supply of lithium
necessitate the development of alternative
energy storage systems. To this end, researchers
have suggested sodium-ion batteries
(SIBs) as a possible candidate.
Besides having physicochemical properties
similar to that of lithium, sodium is
both sustainable and cost-effective.
However, its ions are large with sluggish
diffusion kinetics, hindering their accommodation
within the carbon microstructures
of the commercialized graphite anodes.
Consequently, SIB anodes suffer
from structural instability and poor storage
performance. In this regard, carbonaceous
materials doped with heteroatoms
are showing promise. However,
their
preparation is complicated, expensive,
and time-consuming.
A team of researchers, led by Professor
Seung Geol Lee from Pusan National
University in Korea, used quinacridones as
precursors to prepare carbonaceous SIB
anodes. " Organic pigments such as quinacridones
have a variety of structures and
functional groups. As a result, they develop
different thermal decomposition behaviors
and microstructures. When used as a
precursor for energy storage materials,
pyrolyzed quinacridones can greatly vary
the performance of secondary batteries.
Therefore, it is possible to implement a
highly efficient battery by controlling the
structure of organic pigments precursor, "
explained Lee.
The researchers focused on 2,9-dimethylquinacridone
(2,9-DMQA) in their study.
2,9-DMQA has a parallel molecular packing
configuration. Upon pyrolysis (thermal
decomposition) at 600 °C, 2,9-DMQA
turned from reddish to black with a high
char yield of 61 performed. The researchers
next performed a comprehensive experimental
analysis to describe the underlying
pyrolysis mechanism.
They proposed that the decomposition
of methyl substituents generates free radicals
at 450 °C, which form polycyclic aromatic
hydrocarbons with a longitudinally
grown microstructure resulting from bond
bridging along the parallel packing direction.
Further, nitrogen- and oxygen-containing
functional groups in 2,9-DMQA released
gases, creating disordered domains
in the microstructure. In contrast, pyrolyzed
unsubstituted quinacridone developed
highly aggregated structures. This suggested
that the morphological development
was significantly affected by the
crystal orientation of the precursor.
In addition, 2,9-DMQA pyrolyzed at 600
°C exhibited a high rate capability (290
mAh/g at 0.05 A/g ) and excellent cycle
stability (134 mAh/g at 5 A/g for 1000 cycles)
as an SIB anode. The nitrogen- and
oxygen-containing groups further enhanced
battery storage via surface confinement
and interlayer distance increment.
" Organic pigments such as quinacridones
can be used as anode materials in
sodium-ion batteries. Given the high efficiency,
they will provide an effective strategy
for mass production of large-scale energy
storage systems, " said Lee.
For more information, contact Professor
Seung Geol Lee at seunggeol.lee@
pusan.ac.kr.
A Sodium-Aluminum Battery Aims to Integrate
Renewables for Grid Resiliency
Low-cost, Earth-abundant raw materials power a new grid energy storage solution.
Pacific Northwest National Laboratory, Richland, WA
A
30
new battery design could help ease
integration of renewable energy into
the nation's electrical grid at lower
cost, using Earth-abundant metals, according
to a study just published in Energy
Storage Materials. A research team, led by
the Department of Energy's Pacific
Northwest National Laboratory, demonstrated
that the new design for a grid energy
storage battery built with the lowcost
metals sodium and aluminum provides
a pathway toward a safer and more
scalable stationary energy storage system.
" We showed that this new molten salt
battery design has the potential to charge
and discharge much faster than other
conventional high-temperature sodium
batteries, operate at a lower temperature,
and maintain an excellent energy storage
capacity, " said Guosheng Li, a Materials
Scientist at PNNL and the Principal
Investigator of the research. " We are getting
similar performance with this new
sodium-based chemistry at over 212 °F
lower temperatures than commercially
available high-temperature sodium battery
technologies, while using a more
Earth-abundant material. "
Imre Gyuk, Director of DOE's Office of
Electricity, Energy Storage Program, which
supported this research, noted " This battery
technology, which is built with low-cost
domestically available materials brings us
one step closer toward meeting our nation's
clean energy goals. "
The new sodium-based molten salt battery
uses two distinct reactions. The team
previously reported a neutral molten salt
reaction. The new discovery shows that this
Battery & Electrification Technology, March 2023

Automotive Engineering - March 2023

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