Post on 24-Jul-2020
Carbon Nanotube and Cellulose-Based Energy Storage
Trevor J. Simmons, SangHyun Lee, TaeJoon Park, Daniel P. Hashim, Robert J. Linhardt, Pulickel M. Ajayan*Rensselaer Polytechnic Institute, Troy, NY
*Rice University, Houston, TX
• Discovered in 1991 by Sumio Iijima• Graphene sheets rolled into tubes• Single and multiple wall CNTs exist• Can be semiconducting or metallic• High tensile strength, highly flexible• High surface area, high aspect ratio• Thermally and chemically stable• Can be grown as vertically aligned arrays
Brief Background on Carbon Nanotubes
Wikipedia.org
Cellulose
• Composed of glucose units with β-glycosidic linkage• Main constituent of wood, dried plant matter, paper• Highly fibrous, non-conductive, porous
Why Cellulose?
• Low Cost • Physical Properties
Strong, lightweight, flexible
• Substitute for Petrochemicals• Low Environmental Impact
‘Green Chemistry’ avoids volatile organic solvents
• Renewable FeedstockAgriculture by-product, recycled matter
Problems with Cellulose
• Poor solubility in most solvents• Requires extensive chemical activation
(e.g.: formation of cellulose acetate to make soluble)
• Extraction from native materials(e.g.: lignocellulosic materials such as wood)
Ionic Liquids provide a solution to these problems
Room Temperature Ionic Liquids
• Composed of almost entirely ions• Essentially exist as ‘molten salts’• Very low vapor pressure• High thermal and chemical stability• Remain Liquid over a wide temp. range• Can replace volatile organic solvents• Highly recoverable and recyclable
Total number of Ionic Liquid Publications and Patents 1990-2006
El Seoud et al., Biomacromolecules, Vol. 8, No. 9, 2007
Electrospun Fibers from RTIL
TJ Park et al., ACS symposium series books, Polysaccharide Materials: Performance by Design, 2007
Cellulose Film Electrospun Cellulose Fibers
Vertically Aligned MWNT Arrays from CVD
FerroceneXylene
Argon
800 °C
SiO2 Substrate
Quartz Tube Furnace
Xylene-Ferrocene MWNT
Completed Nanotube Material on SilicaDeposition of Cellulose from RTIL
Cellulose dissolved in RTIL
RTIL in Cellulose
Ethanol
[Cl] -
[CH3COO] -
[PF6] -
emim
bmim
Anions (-) Cations (+)RTIL of Interest:
[bmim]Cl
[bmim]PF6
[emim]CH3COO
• Comparison between [Bmim][Cl] and [Emim][acetate]
E. Uerdingen (BASF) “Current status in ionic liquids technology”, ERC symposium in Korea.
Composite Material Removed from Substrate
Titanium Metal DepositionGold Metal Deposition
CelluloseIn RTIL
IonicDiffusion
Pushparaj et al., PNAS, 2007, 104, 34
Mechanism of Charge Separation
Super-Capacitor Device
Applied Voltage
Improved infiltration of cellulose will enable enhanced capacitance
Electric Double Layer
Cellulose-based Lithium Battery
Why Replace Existing Li-Batteries?
• Price - If you disagree, can you please buy me some?
• Weight - a majority of a device weight is the battery
• Reliance on Petrochemical Polymers• Short lifetime in non-optimal conditions• Hazards posed by dangerous reactions:
Lithium Metal Volatile Organic ElectrolyteBurns on contact with air/moisture Flammable, thermally unstable
According to the US Consumer Product Safety Commission there were 339 incidents of:
“overheating, emitting smoke and fumes or exploding since 2003.”
Benefits of Cellulose Battery Design
• Inexpensive, scalable process• Low-toxicity materials• Non-flammable electrolyte• Avoids use of highly reactive lithium metal
MWNT LiCoO2
Cu
Cur
rent
Col
lect
or
Al C
urre
nt C
olle
ctor
Au/Ti Cellulose
Anode(-) Cathode(-)
Cellulose with TiO2 and Li+
20-50 μm
Anode(MWNT)60-100 μm
Cathode(LiCoO2)
Au200-400 nm
Ti20-100 nm
Layer Thickness(not drawn to scale)
cellulosewith TiO2
Anode(MWNT)
Cathode(LiCoO2)
Al c
urre
nt c
olle
ctor
Charging
+
+
++
+
+
+
+
+
+
Li+
+
AnodexLi+ + Cn → LixCn
Li+ insertion
CathodeLiCoO2 → Li1-xCoO2 + xLi+
Co oxidation
Cn + LiCoO2 → LixCn + Li1-xCoO2
e-
Cellulose and Electrolyte(LiTFSI and [CrBim]TFSI)
Intercalated Li
LiCoO2Cathode
Li
Li
Li
CelluloseCurrentCollector
+
+
+
electron
lithium ion
-
-
-
-
Li
Li
Li
Intercalated lithium lithiumcobalt oxide
Carbon Nanotubes
Charging
AnodeLixCn→ xLi+ + Cn
Li+ extraction
CathodeLi1-xCoO2 + xLi+ →LiCoO2
Co reduction
LixCn + Li1-xCoO2 → Cn + LiCoO2
cellulosewith TiO2
Anode(MWNT)
Cathode(LiCoO2)
Al c
urre
nt c
olle
ctor
Cellulose and Electrolyte(LiTFSI and [CrBim]TFSI)
++
+
++
++
+
++
+
++
+
Li++
+
e-
Discharging
LiCoO2CathodeCellulose
CurrentCollector
-
-
-
-
-
-
Li
Li
Li
Intercalated lithium
Carbon Nanotubes
+
+
+ Li
Li
Li
lithiumcobalt oxide
lithium ionDischarging
Lithium Intercalation
Expansion of graphene sheets can lead to exfoliation
Lithium Intercalation
MWNT cannot expand like graphite, and rupturing can occur
Flexible nanocompositeEnergy device
Voltage(V)
Capacity Specific Energy(Wh/Kg)
Specific Power(W/Kg)
Operating temperature
(o K)Thin film Paper
battery(Liquid electrolyte)
3.6 110 mAh/g 300 140 273- 333
Supercapacitor(RTIL electrolyte)
2.2 80 F/g 13 1500 195 - 450
Flexible nanocomposite energy devices
Conclusions• Ionic Liquids are excellent cellulose solvents• RTILs can be easily recycled and reused• Cellulose is an alternative to high-dielectric
synthetic polymers based on petrochemicals• Carbon nanotubes can replace graphite as a
high surface area electrode material• Super-capacitors and Li-Ion batteries can be
made from cellulose, RTILs, and CNT
AcknowledgementsAdvisors
Dr.Pulickel AjayanDr.Robert LinhardtDr.Robert VajtaiDr.Fuming Zhang
Co-Workers
Dr.Sang Hyun LeeTae Joon ParkDr.Justin BultDaniel HashimDr.Ashavani KumarDr.Victor PushparajDr. M. ShaijumonDr. Swastik Kar
Funding Sources• NSF award DMR-0303174
• NSF Materials World Network: Fabrication of Polymer Composites and Sensors Using Doped Nanotubes (DMR-0801012)
• NSF-funded Nanoscale Science and Engineering Center on directed assembly of nanostructures.
• NYSTAR New York State Office of Science, Technology,and Academic Research
• National Institutes of Health grant AI06578
Results of Electrochemical Tests
Pushparaj et al., PNAS, 2007, 104, 34