Transcript Szamreta_Nicholas_sol _sm

MEASURING THE INTRINSIC CAPACITANCE
OF GRAPHENE/IONIC LIQUID INTERFACES
FOR HIGH ENERGY DENSITY
SUPERCAPACITORS
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Nick Szamreta
Summer of Learning Symposium
October 4th, 2013
LOGISTICAL OVERVIEW
8 week internship funded by PEI
 Facilities at Ceramic Materials Lab (Prof. Ilhan A.
Aksay) in Princeton
 Collect data on intrinsic capacitance useful for the
design of supercapacitors

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SUPERCAPACITORS

High Power
Density


Can charge
and discharge
quickly
Low Energy Density
 Depends on electrode material
(Functionalized Graphene Sheets)
 Depends on operating voltage
(Ionic Liquids)
E ~ CV2
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IONIC LIQUIDS
Bmim+
Tf2n-
Emim+
Bf4-
Pipip14+
Cation (Abbrev.)
Anion (Abbrev.)
1-ethyl-3methylimidazolium
(emim)
bis(trifluoromethylsulfo
nyl)imide
(tf2n)
1-ethyl-3methylimidazolium
(emim)
Tetrafluoroborate (bf4)
1-butyl-3methylimidazolium
(bmim)
bis(trifluoromethylsulfo
nyl)imide
(tf2n)
1-butyl-4methylpiperidinium
(pip14)
bis(trifluoromethylsulfo
nyl)imide
(tf2n)
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REASONS FOR STUDYING IONIC LIQUIDS
Electrolyte
Electrochemical
Window (V)
Emimtf2n
4.3
Bmimtf2n
4.8
Emimbf4
4.2
Pip14tf2n
5.0
Aqueous Electrolytes
1-2
Organic Electrolytes
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
Large
electrochemical
windows

Thermal stability

Low vapor
pressure

How do these
different
properties affect
capacitance?
Barrosse-Antle et al. (2010), Voltammetry in RTIL. Chem. Asian Journal.
E ~ CV2
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INTRINSIC CAPACITANCE MEASUREMENTS
Three electrode system
 Impedance Spectroscopy

Measures the response to an
AC signal
 Allows us to probe the
interface and its
electrochemical properties


Intrinsic data for specific
combinations of materials is
valuable for supercapacitor
design

Measurements are much more
controlled than a device
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SAMPLE DATA

Allows us to
compare
different
materials and
electrolytes
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CONCLUSIONS AND CONTINUED WORK
Ionic Liquids are promising electrolytes for
supercapacitors in conjunction with FGS
 Testing other ionic liquids
 Diluting ionic liquids to increase power density
 Building and testing devices

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ACKKNOWLEDGEMENTS
Dr. Ilhan A. Aksay
 DJ Bozym
 Dr. Michael Pope
 PEI

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