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National Graphene Institute Graphene-Based Materials for Energy Storage Applications
Paul Wiper, PhD, MSc.
Research Associate
Graphene energy storage and conversion
devices
Energy Storage Systems
CO2by 80% by 2050
CO2
Capture
TowardsRenewable
Energy
Energy Storage Systems
Electrical Mechanical Thermal Chemical
• Superconducting magnetic energy
storage• Capacitors
• Supercapacitors
• Pumped hydroelectric
• Compressed air• Flywheels
• Hot water cylinders
• Batteries • Lithium-ion
ESS
http://www.energystorageexchange.org
Perspectives for Electric Vehicles
Nature Mat. 2012, 11, 19-29http://www.autocar.co.uk/car-review/tesla/model-s/design
Tesla S Model:>7000 LIBs (nickel cobalt aluminum) (NCA) Panasonic ~ 260 m > 400 km (85 kWh) 240 V output, 1 hour = 60 miles 4.3 hrs total charge
20122015
2015
Li+ ion
LiC6; GraphiteLiCoO2
Chem. Rev. 2014, 114, 11636−11682
Traditional Li-ion Cell:
Electrochemical
Capacitors
• V applied > opposite charges accumulate on the surfaces of each electrode
• Charges are kept separate by the dielectric, thus producing an electric field
• Capacitors store energy in its electric field
pF-μF g-1
Supercapacitors
+ + + ++ ++
- - - --
-• Double-layer formed at
the interface between the solid electrode material surface and the liquid electrolyte in the micropores of the electrodes
Increase Surface Area of electrodes
Decrease distance dielectricF g-1
Batteries vs. Supercapacitors
Batteries vs. Supercapacitors
Graphene based electrode materials
Graphene-based Electrodes
J. Mater. Chem. A, 2014, 2, 15–32
Production of Graphene for Electrodes
NMP (N-methyl-2-pyrrolidone)
Ultrasonicator
Dispersed graphene
flakes
Liquid Phase Exfoliation (LPE)
Exfoliated graphene nanosheets
Ultracentrifugation
Surfactants
• Low-cost and mass scalable• Produce high quality graphene
Opt. Mater. Express. 2014, 4, 63-78Science, 2013, 340, 1-18
LIBs: Graphene-based Materials for Anodes
Material Anode Specific capacity (mAh g-1)
Graphite 372
Graphene nanosheets (GNS) 540
GNS/CNT 730
GNS/C60 784
GNRs (Rice Uni) 850
ACS Nano, 2011, 5 (7), pp 5463–5471
• Silicon is the most promising, owing to its high natural abundance, low discharge potential, and high theoretical charge capacity (3579 mAh g−1)
• Large volume changes (up to 270% for the Li3.75Si phase)• Loss of electrical contact during lithium insertion and
extraction result in capacity fading
• Reducing the Si particle size to the nanoscale• Dispersing the electroactive particles in a carbon matrix
- It is believed that carbon-based materials buffer the volume changes and improve the electronic and ionic conductivities
LIBs: Graphene-Silicon Composite for Anodes
LIBs: Graphene-Silicon Composite for Anodes
Journal of Power Sources 2015, 287, 177-183Electrochemistry Communications 2010, 12, 303–306
Si dendrites
Graphene
Charge/discharge curves of the composite electrode (0.5 mV/s over 0.01-2.5 V)
Si/G electrode delivers a reversible initial capacity of 2280 mAh g−1 and a capacity retention of 85% even after 100 cycles and a capacity as high as 1521 mAh g−1
Commercialisation of Graphene Anodes for LIBs
Graphene-Silicon Anodes (USA)
Market now:
Graphene-Silicon Anodes (USA)
Graphene-Silicon Anodes (USA)
Graphene-LIBs (USA)
LIBs: Graphene-based Materials for Cathodes
LiCoO2 LiMn2O4LiFePO4
Characteristics of commercial LIB cathode materials
R.J. Brodd (ed.), Batteries for Sustainability: Selected Entries from the Encyclopedia of Sustainability Science and Technology,Springer, Scienc-Business Media New York 2013
LIBs: VO2-Graphene Composite for Cathode
43 s 19 s
VO2-Graphene nanoribbon composite
90% after 200 cycles at 28C!
“breakthrough in cathode materials…high power lithium ion batteries”
Nano Lett. 2013, 13, 1596−1601
Li-S Batteries
• Li: X10 higher energy density of graphite anodes• S: abundant, high energy density, low price…
• Low conductivity of S • Volume increase • Polysulfide ion shuttle
Pros
Cons
Chem. Commun., 2012, 48, 1233–1235 1233
Commercialisation of Graphene Li-S
Graphene-Li-S (UK)
Li-air Batteries
• Li: X10 higher energy density of graphite anodes• Air: Abundant/light weight!
• Instability of the Li metal – dendrite formation • Limited reversibility of the electrochemical process
Nano Lett. 2011, 11, 5071–5078Nature Mat. 2012, 11, 19-29
15,000 mAh g-1
Pros
Cons
Alternatives to LIBs:
Nature 2015, 520, 325-329Chem. Rev. 2014, 114, 11636−11682
Energy density ~ 40 W h kg-1
Power density ~ 3,000 W h kg-1
Al-IBsNa-IBs
Improving the Energy Density of Supercapacitors
Graphene-Based Electrodes for SuperCaps
Chem. Soc. Rev., 2015, 44, 3639-3665
LaserScribe Graphene SuperCaps
LaserScribe GO SuperCaps
“Wearable energy and power-dense supercapacitor yarns enabled by scalable graphene–metallic textile composite electrodes”
Graphene-Based Wearbale SuperCaps
Nature Comms. 2015, 6:7260
Overview
• Extensive research into graphene-based electrodes in LIBs and Supercapictors
• Commercially viable technologies
• Investment and big players to take technology forward
