BEN Event - 20/04/10 - Think Small, NSQI Building, University of Bristol.

1. Think Small
20 April 2010
Nanomaterials for Green Energy
Tim Mays ( t.j.mays@bath.ac.uk )
Department of Chemical Engineering

2. A core element of energy policy
must be to ensure the provision of
sustainable, secure and safe heat
and power for everyone

3. Scope
Some examples of nanomaterials
for green energy:
• batteries
• energy efficient lighting
• hydrogen storage

7. Li Batteries: Portable Revolution
• Energy density small & light
• Over 2 billion cells per year
• Fundamental science (1980s)
SONY cell (1991)

8. Low Carbon Transport:
HEVs & Li Batteries?
“Materials Challenge”
New or improved materials are key
to major advances:
performance, cost

9. Energy Storage: lithium battery
Charge
Li+
Discharge
Li+ - conducting
LixCoO2 cathode electrolyte Graphite anode
Hybrid
TRANSPORT
~30%+ CO2 emissions
87% cleaner

10. New or Improved Materials:
Key to major advances
“Spinel” “Layered” “Olivine”
LiMn2O4 Li(Mn,Ni)O2 LiFePO4
Structure-property relationships: atomic-scale insight
into Li transport, defects, dopants & surfaces

11. New LiFePO4 Cathode
Scale-up
Defect chem?
Li+ transport ?
Doping: Zr,Nb?
Blue: PO4
Yellow: FeO6

12. LiFePO4: Li Diffusion Path?
[010] channel (0.55eV) & curved path
[010]
[100] Li
FeO6 octahedra PO4 tetrahedra
Chem. Mater (2005)

13. M Saiful Islam
Department of Chemistry

14. Nanoparticle Factory-on-a-Chip
Vision: ‘Large scale production of nanoparticles with controllable and reproducible
characteristics will lead to a radical shift in all manufacturing sectors …’ (RAEng/Royal Soc., 2004)
Methodology: Forcing water through a nanoporous membrane into an immiscible solvent produces
nanodroplets, which are then converted into nanoparticles, with control over particle shape, size and properties:
organic
solvent water
10 nm
nanoporous alumina membranes
nanoparticles have billions of pores per cm2.
organic
L2
solvent
Large scale manufacturing of
water
L1 nanoparticles with controllable
and reproducible properties.

15. Nanoparticles are currently used in many applications (fuel cells, sun-blocking creams, solar
panels, fuel additives…) but transformative developments are hindered by the lack of methods
to produce large quantities of nanoparticles with controllable and reproducible properties.
One example of what will be possible to achieve with better nanoparticle property control:
© Benoit Dubertret, 2004
Diameter (nm)
Lighting fixtures based on quantum dot nanoparticles are 20-30 % more efficient that
fluorescent bulbs and do not contain harmful chemicals. Prototype quantum dot-based
displays are already more efficient than conventional LCD displays.
Today they are made in batches of a few milligrams at a time, against projected market
demand of three tonnes per year by 2012!
(The Economist, 04/03/2010; data from Coe-Sullivan, Nature Photonics, 3, 315-316, 2009 )

17. Davide Mattia
Department of Chemical Engineering

19. Hydrogen energy
hydrogen + oxygen → water + energy
2H2 + O2 → 2H2O
energy = 120 - 142 MJ/kg heat (combustion)
= 1.23 V electrical potential + 24 MJ/kg heat (fuel cell) +
TE
NO
Only material product of above reaction is water
Compare: hydrocarbon + oxygen → water + carbon dioxide + …
A lot of energy per unit mass of hydrogen
Compare: 40-55 MJ/kg for combustion of hydrocarbons
TE
NO

20. Basic principles of hydrogen energy systems
Ein time / location
Eout
energy produce store / energy
in hydrogen distribute out
electricity liquid hydrogen combustion
water
heat high-pressure gas fuel cell
biomass
light chemical storage
fossil fuels
radiation porous solids 2H2+O2 → 2H2O
many available many available H2 easier to store
no CO2 at
sources of sources of than many energy
point of use
energy H2 forms

22. Hydrogen storage
technologies

23. Nanopores
Mays, Stud Surf Sci Catal
160 (2006) 57
Familiar nanoporous materials

25. A core element of energy policy
must be to ensure the provision of
sustainable, secure and safe heat
and power for everyone
Nanomaterials will have an
important role in future low
carbon energy technologies