1
Direct alcohol fuel cells
Eocell (V) n 1 MeOH
1.20 n 2 EtOH 1.14
6n e
6n H H2O
n CO2,(g)
3n H2O
CnH2n1OH
(3n/2) O2
CnH2n1OH (2n 1) H2O
PEM
Anode (-)
Cathode ()
PEM proton exchange membrane
2
Direct borohydride fuel cell
8e-
Eocell (V) 1.64
NaBO2 6H2O
8 Na H2O
4H2,(g)
H2O
8NaOH
NaBH4 2H2O
2O2
NaBH4 8NaOH
PEM
Anode (-)
Cathode ()
PEM proton exchange membrane
3
Highlights of direct fuel cells

• Advantages
• Ethanol and methanol are primary liquid fuels
  obtainable from renewable, agricultural,
  resources sustainable energy
• Canada is a leader in both ethanol (240 million
  liters annually from agricultural resources) and
  methanol production (Methanex)
• The borohydride fuel cell (DBFC) is a zero-carbon
  emission power source
• Higher theoretical energy densities compared to
  H2 H2-O2 fuel cell 550 kWh m-3H2
  (at 200 atm, 293 K)
• DMFC 4,800 kWh m-3 CH3OH
• DEFC 6,300 kWh m-3 C2H5OH
• DBFC 2,000 kWh m-3 (20 wt NaBH4 in 2 M NaOH)

4
Disadvantages Problems to be solved

• Poor anode performance
• Sluggish fuel electro-oxidation kinetics /
  electrocatalysis
• CH3OH oxidation Pt-Ru
• C2H5OH oxidation Pt-Sn
• NaBH4 oxidation Au, Pt, Metal-Hydrides
• Effect of catalyst composition, operating
  conditions
• Low catalyst layer utilization efficiency
• Catalyst preparation method particle size
  dispersion on and interaction with
  various supports ionomer network /
  catalyst interface
• Two-phase flow in the porous anode
• For alcohol fuel cells CO2 disengagement from
  the catalyst layer mass transfer
  overpotential and effective ionic conductivity
• Fuel crossover from the anode to the cathode
• Membrane permeable to alcohols mixed
  potential on the cathode

5
Research strategy
Surface analytical studies
- surface area, composition etc.
Cell Design variables
Colloidal precursor method
Nano-scale electrocatalyst synthesis and
deposition on substrates
Liquid crystal templated /surfactant assisted
electrodep.
Evaluation of electro-catalytic activity
Fuel cell testing and optimization
Electrochemical methods Voltammetry, impedance,
chrono-techniques
Electrodeposition from microemulsions and
micellar media
Operating conditions
6
Typical gas diffusion anode structure for direct
fuel cellsMight not be the best engineering
solution we are looking at alternatives
5 25 ?m
CO2,(g)
H2O
H H2O R-OH
C A T H O D E
NaBO2, H2,(g)
CH3OH, C2H5OH
O2
Na H2O BH4-
NaBH4
Carbon fiber diffusion layer
Catalyst layer
Ionomer (e.g. proton exchange membrane)
7
Acknowledgement

• NSERC
• Discovery Grant
• Equipment Grant
• BC ASI
• Provincial Research Fellow
• WED / CFI
• Auto 21
• Industrial collaborations
• Consultant for Vizon Sci Tech. (2002-2003)
• Colgate-Palmolive USA (2005)
• Tekion (2006-2007)