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A D V A N C E D
M A T E R I A L S
&
P R O C E S S E S |
M A Y
2 0 1 6
1 3
Oklahoma City Bombing, include
alkane-containing fuel oils. .
2D ELECTRODE ENERGY
STORAGE MAKES HEADWAY
Researchers at Oak Ridge Nation-
al Laboratory (ORNL), Tenn., observed
for the first time at the nanoscale
and in a liquid environment how ions
move and diffuse between layers of
a MXene electrode during electro-
chemical cycling. MXene—a 2D mate-
rial composed of carbon or nitrogen
sandwiched between transition metal
layers—exhibits very high electrical
capacitance and is being explored as a
next-generation energy storage mate-
rial for supercapacitors and batter-
ies. Using scanning probe microscopy
and theoretical calculations, the team
explored how ions enter and migrate
within the MXene and how they inter-
act with the active material. Scientists
observed that when positively charged
cations are introduced into the neg-
atively charged MXene material, it
becomes stiffer. The team measured
local changes in stiffness and found
Professor Ling Zang displays a prototype
handheld detector that can sense explo-
sive materials and toxic gases. Courtesy
of Dan Hixson/University of Utah.
When a negative bias is applied to a 2D
MXene electrode, Li+ ions from the elec-
trolyte migrate in the material via specific
channels to the reaction sites, where
the electron transfer occurs. Courtesy of
ORNL.
a direct correlation between the dif-
fusion pattern of ions and stiffness.
Working within a liquid environment
allowed measurement of mechanical
properties in-situ at different stages
of charge storage, providing direct
insight about where ions were stored.