Direct methanol fuel cells – ready to go commercial?

FEATURE
Direct methanol
fuel cells – ready
to go commercial
By George Apanel (SRI Consulting, Houston, Texas, USA) and Eric Johnson
(Atlantic Consulting, Zürich, Switzerland)
DMFCs are about to come of age as transportable power supplies. A motor
scooter is already headed towards serial production; next in line will be cell
phone power packs, portable generators and perhaps even automobiles. This
article reviews the development of direct methanol fuel cells, current players in
the market, key technical challenges and the current cost picture.
and the presumption is that it will stay that
way or even increase.
• For stationary applications, hydrogen or natural
gas appear to be the best fuels (if a lowcost
distribution infrastructure is in place),
but liquids are more desirable for mobile
applications. Methanol is attractive: first,
because it is cheap, and secondly, because it
converts directly to electricity without the
need for a bulky reformer in the middle.
Reflect for a moment, if you will, on the title of
this article. To some it will seem completely
mundane: ‘Of course DMFCs are ready to go
commercial!’ To others, especially those who
have seen energy crises and fads come and go,
the title might seem more provocative.
Remember, only a few decades ago it was
thought that by now we would eat pills for
meals and drive flying cars.
Besides, fuel cells have been waiting in the
wings for a long time. It was back in 1839
when William Grove, a Welsh judge, constructed
the first known fuel cell. His device
electrochemically reacted hydrogen with oxygen.
But it took more than another century
for the first practical application of fuel cells
to occur. This was for US outer-space exploration
in the early 1960s. The need for an
efficient, long-lasting, non-polluting, compact
power source within the cramped confines
of a space vehicle made fuel cells the
right choice, despite their high initial cost of
materials and development.
All well and good for technological progress,
but this was still a long ways off from commercial
viability. The US space program, with its
famed $640 toilet seats, is hardly a conventional,
for-profit market.
Nonetheless, our research suggests that
DMFCs’ time is nearly come. They could soon
be used on a competitive, commercial basis to
power cell phones, portable electric generators
and vehicles. Indeed, a DMFC-driven motor
scooter is about to see its market debut.
Why should we be any more optimistic than
the Welsh judge There are two main reasons:
• As readers of the Fuel Cells Bulletin know,
the beauty of fuel cells is their energy efficiency,
as shown in Figure 1. (The other
attraction is their relatively mild operating
conditions.) For economic, social and environmental
reasons, efficiency has become
much more important in the past few years,
Stranded gas – the reason
behind cheap methanol
The earth’s proven reserves of natural gas are –
in terms of energy value – about 80% of the
size of its proven oil reserves. Unfortunately,
60% of this gas (an estimated 3000 trillion
cubic feet) is so impolite as to locate itself in
inconvenient places such as Tierra del Fuego or
Figure 1. High efficiency – the promise of fuel cells. [Source: A.J. Appleby et al.: Fuel cell handbook
(Van Nostrand Reinhold, NY, USA, 1989).]
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Fuel Cells Bulletin November 2004

FEATURE
on the North Slope of Alaska. This so-called
‘stranded’ gas can be drilled and brought to the
surface, but it is still too remote to be transported
economically to its potential markets.
Sometimes stranded gas is brought to the
surface anyway, because it is locked in underground
formations together with oil that can be
(and is) extracted economically. This stranded,
‘associated’ gas is either re-injected into the
earth (11 trillion cubic feet in 1998), burnt
near the wellhead (known as ‘flaring’) or even
just vented to the atmosphere. If the 3.8 trillion
cubic feet that were flared and vented in 1998
were instead reacted with water at the right
temperature and pressure, the result would be
approximately 74 million tonnes of methanol.
This is about three times the 25.7 million
tonnes actually produced that year, so the
potential here is huge. Moreover, burning or
venting fuel is terribly ‘politically incorrect’
these days, not least thanks to concerns about
global warming and sustainability. Finally, the
spike in oil prices of the past few years has
shifted the economics of stranded gas – some of
those far-off places are looking closer than they
used to.
One option, of course, is to compress the gas
into liquefied natural gas (LNG), and then ship
it to market. This involves construction of a
costly liquefaction plant, as well as specialized
shipping and terminal facilities, and in some
cases captive power plants bound by long-term
supply contracts. A typical grassroots LNG project
liquefying approximately 980 million standard
cubic feet (SCF) per day of natural gas for
producing about 6 million tonnes per year of
LNG could cost US$5–10 billion if the cost of
the power plant is included with the production
facilities.
Another option is a gas-to-liquids (GTL)
plant, where the natural gas is converted by a
series of reactions into a fuel similar to diesel.
Shell is building a major gas-to-liquids unit to
liberate stranded gas in Qatar, and other such
projects are on the drawing board.
Yet another option is to use stranded gas to
make either of two petrochemicals: ammonia or
methanol. (Indeed, most recent additions to
capacity of these products are in remote locations.)
A major attraction of these is that the
capital investment required for such projects is
an order of magnitude lower than for LNG or
gas-to-liquids. Furthermore, a world-scale
methanol plant can operate on a gas field that is
too small to justify an LNG or gas-to-liquids
operation. Indeed, such methanol plants can
even be mounted on barges, and then moved
from field to field. On the other hand, pricing
in chemical markets is notoriously volatile.
Great ideas can be – and often are – washed
away in a flood of overcapacity or a shift in
demand.
If there were a stable fuel market for
methanol, so much the better. (Currently there
are fuel markets for it, but they are anything
but stable.) Rest assured, methanol producers
are watching fuel cell markets anxiously.
Indeed, one of the major producers, Methanex,
is co-sponsoring the development of a DMFCpowered
motor scooter.
Choose me, choose me –
methanol’s mobility
advantage
In mobile applications, liquid fuels are usually
preferable to gaseous ones, and often to solid
ones as well. So, not surprisingly, researchers
have long been on the lookout for a fluid that
would also be a suitable fuel.
Methanol was an obvious candidate early on,
because it:
• can be readily made via a well known manufacturing
process from plentiful raw materials;
• remains liquid under normal storage conditions
(unlike, say, butane, which tends to
evaporate much more easily);
• is compatible with the existing fuel distribution
infrastructure;
• is relatively hydrogen-dense, i.e. four of the
six atoms in methanol (CH 3 OH) are hydrogen;
and
• is environmentally acceptable.
Figure 2. First through a reformer – an indirect methanol fuel cell.
In the 1990s, development began of an indirect
methanol fuel cell (Figure 2). A fuel processor
(also known as a reformer) was used to convert
methanol into hydrogen-rich gas for protonexchange
membrane (PEM) fuel cells.
Reforming to produce hydrogen from
methanol is well known on an industrial scale.
At temperatures of 250–300°C, methanol is
reacted with steam over a copper-zinc or copper-chromium
catalyst into hydrogen and CO 2
via the following reaction:
CH 3 OH + H 2 O → CO 2 + 3H 2
Methanol enters the fuel processor where it is
vaporized, combined with water and converted
into moist, hydrogen-rich reformate. The carbon
monoxide byproduct is removed from the
reformate via a gas purification system.
The purified, hydrogen-rich reformate is fed
to the fuel cell’s anode chamber, where the
hydrogen is oxidized while oxygen (in the
form of air) is reduced at the cathode. Air is
supplied to the cell via a compressor. The
compressed cathode effluent gas passes
through an expander to recover some of the
energy from the compression step. The spent
fuel from the anode chamber contains some
residual hydrogen, and is fed to a catalytic
burner to provide heat for methanol vaporization
and the endothermic steam methanol
reformer.
The downsides here are:
• because this reaction consumes energy, the
reformer needs supplemental heat; and
• the reformer adds sizable capital costs, and it
can be bulky.
Nevertheless, DaimlerChrysler has shown that
it can work. In 2001 its Necar 5 prototype –
which used a methanol reformer based system
– was driven in a pilot test right across the
United States.
November 2004
Fuel Cells Bulletin
13

FEATURE
Of course, other liquid hydrocarbons can
also be reformed to hydrogen. In fact, the same
features that make methanol a good fuel candidate
also apply generally to gasoline, although
the gasoline reformer would be even more complicated
and less efficient. What sets methanol
apart from those hydrocarbon fuels is its ability
to be fed directly into a fuel cell, which cuts out
the reformer with its associated costs and
headaches. This is possible because, like all alcohols,
methanol contains oxygen: this makes it
more reactive than plain hydrocarbons.
This was first recognized in 1922 by the
German researcher E. Müller, who studied
electro-oxidation of methanol. By 1951, Karl
Kordesch and Adolf Marko had begun construction
of a direct methanol fuel cell based on
Müller’s early concept.
DMFC interest fired up again about a decade
later, this time focused on military applications.
Alkaline electrolytes were tested by researchers at
Allis-Chalmers in 1963. DMFCs based on aqueous
acid electrolytes, which do not react with
CO 2 produced at the anode, were developed by
researchers at Esso and Shell in 1965. Esso
developed a 100 We DMFC for powering communication
equipment. Shell found Pt-Ru to be
most effective as an anode electrocatalyst, and
developed a 300 We system prototype in 1968.
Progress then mostly hibernated until 1992,
when DuPont’s Nafion solid polymer electrolyte
membrane was found to be far superior
to the old medium of sulfuric acid (Figure 3).
In 1994, the Jet Propulsion Laboratory in
California demonstrated a Nafion-based
DMFC, and since then, a new wave of development
has been rolling.
Key players in DMFCs
In our research, we have identified 15 companies
that are leading the development of
DMFCs. They are listed here in alphabetical
order, with a brief discussion of each.
Ball Aerospace & Technologies
20 W electrical output for medical devices, cell
www.ball.com/aerospace
phones, PDAs, laptops and other wireless
The Colorado-based company is developing a devices. Giner Electrochemical Systems, which
handheld 20 We DMFC power system for the is a joint venture between Giner Inc and
US Defense Advanced Research Projects General Motors, has also delivered a complete
Agency (DARPA) Palm Power Program. This liquid-feed direct methanol fuel cell system providing
a 50 We/12 V output to the US Army
compact electrical power source is primarily
intended for foot soldiers and robotics under Research Laboratory.
battlefield conditions, but may find other
emerging, non-military applications. If this
1.5 lb (700 g) device were used to power a laptop
computer, it could run continuously for
three days between methanol refills. While the
DMFC device is similar in size to three videocassette
tapes, 22 lbs (10 kg) of conventional
batteries would otherwise be required for such a
continuous service interval.
Direct Methanol Fuel Cell
Lynntech Industries (nowFideris)
Corporation
www.dmfcc.com
This company, founded in California in 2002,
aims to commercialize DMFC knowhow developed
at the California Institute of Technology/
NASA Jet Propulsion Laboratory (JPL) and the
University of Southern California. The company
has acquired the rights to 26 issued and
more than 40 pending US and foreign patents
on JPL’s DMFC technology.
Figure 3. The power (and voltage) of Nafion. [Source: S. Srinivasan et al.: Techno-economic challenges
for PEMFCs and DMFCs entering energy sector. First International Conference on Fuel Cell
Science, Engineering & Technology, Rochester, NY, USA, April 2003.]
Giner Electrochemical Systems
www.ginerinc.com
Massachusetts-based GES has announced its
demonstration of a simplified DMFC, based on
a novel method of supplying methanol to the
fuel cell. This is particularly attractive to micro
and low-power fuel cells of up to approximately
H Power/Plug Power
www.plugpower.com
US-based H Power (subsequently acquired by
Plug Power) was in a joint development agreement
with DuPont Fluoroproducts to develop
DMFCs in the range from 100 to 1000 We for
portable and mobile applications.
www.fideris.com
A new generation of test systems for DMFCs
has been launched by this company, which
recently changed its name and relocated to
Massachusetts. The company has also delivered
four prototype, self-contained DMFC 15 W/
12 V power supplies to the US Army Research
Laboratory.
Manhattan Scientifics
www.mhtx.com
NY-based Manhattan Scientifics is commercializing
DMFC technology developed by former
Los Alamos National Laboratory researcher
Bob Hockaday at Energy Related Devices in
Arizona. The company has a proprietary
method for the use and manufacture of
MicroFuel Cell power devices, which are
aimed at portable electronics such as cell
phones, laptop computers, camcorders and
power tools. Manhattan Scientifics has used
MicroFuel Cell technology to create its Power
Holster, a portable charger/cell phone carrier.
Fueled by disposable ampoules containing
methanol, the fuel cells can also use cartridges
that provide hydrogen gas generated by a sodium
borohydride/water reaction. Generating
approximately 1 W of electric power, the
MicroFuel Cell array in the unit consists of 10
cells in a 4.7 inch long × 1.8 inch wide × 0.02
inch thick (120 × 46 × 0.5 mm) package. The
cells are formed on paper-thin plastic sheets
intended for roll-fed mass production. The
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Fuel Cells Bulletin November 2004

FEATURE
specific energy density of its MicroFuel Cell is
940 Wh/kg, which is between six and nine
times that of commercial Li-ion batteries.
Mechanical Technology Inc/
MTI Micro Fuel Cells
Medis Technologies
www.medistechnologies.com
US/Israeli-based Medis has completed the first
phase in the development of its direct liquid Technology
methanol (DLM) fuel cell for portable electronic
devices. The 1 × 1 × 3/8 inch (25 × 25 × 10 In Korea, Samsung has demonstrated a 40 We
www.sait.samsung.co.kr
mm) DLM fuel cell module delivers 0.24 We at DMFC (12 V/3.4 A) that operates a notebook
0.9 V. The company plans to package its fuel PC for more than 6 h without charging. Core
cells as individual modules (‘chips’) for manufacturers
of portable electronic
technologies for miniature DMFC cell packs
devices.
Motorola Labs
NEC
up the PDA. Thus, it is anticipated that the
www.labs.nec.co.jp/Eng/innovative/E1/top.html
battery will be replaced by an ultracapacitortype
device before the DMFC is commercial-
Japanese electronics giant NEC has announced
a miniature DMFC based on applied nanotechnology.
The power output is claimed to be market a DMFC for notebook PCs.
ized. Toshiba has also announced plans to
about 10 times that of a Li-ion battery with the
Samsung Advanced Institute of
are under development that will power cell
phones and PDAs. The company has also
developed a credit-card-sized DMFC which
www.motorola-labs.com
would fit into a cell phone, which it hopes to
US giant Motorola has demonstrated a prototype
of a miniature integrated, ceramic-based, power density of 50 mW/cm 2 , and a total
commercialize by 2005. It has a maximum
reformed methanol-to-hydrogen fuel cell electric power output of 2000 mW.
(RHFC). The device incorporates an integrated
methanol vaporizer and steam reformer.
The company has also demonstrated a prototype
ceramic-based DMFC which could power
www.smartfuelcell.com
German-based Smart Fuel Cell is developing
a cell phone for a month between methanol
compact DMFC systems for the portable electronics
and small portable generator markets. A
refills. The fuel cell assembly fits into a belt
holster, with methanol stored in a small cartridge.
The device is designed to either power
portable DMFC power supply unit, fueled by a
replaceable methanol cartridge, will soon be
a cell phone directly, or to recharge a conventional
battery pack for powering the phone.
commercially available on a limited basis to
industrial customers. SFC has demonstrated a
The assembly measures about 2 × 4 × 0.5
inches (50 × 100 × 12 mm). The device integrates
miniature methanol concentration sensors,
liquid-gas separation for CO 2 release,
pumps and control electronics. A highly simplified
and miniaturized passive air design www.toshiba.co.jp/rdc
Toshiba
eliminates the need for condensers, heatexchangers
and other complex devices. The totype DMFC for powering a PDA. It has a
The Japanese company has demonstrated a pro-
company appears to be planning commercial power density of 30 mW/cm 2 at a constant
fuel cell product introductions for cell phones average power output of 5 We. However, an
by 2005–2006.
auxiliary rechargeable battery is required to start
Yuasa Corporation
same volume. The company says it plans commercial
product introductions by 2005 for
www.mtimicrofuelcells.com
MTI Micro in Latham, NY is using technology
www.yuasa.co.jp
notebook computers and cell phones.
licensed from Los Alamos National Laboratory,
This Japanese battery manufacturer has demonstrated
DMFC prototypes with electric power
from where some of its key staff (including its
chief technology officer, Dr Shimshon PolyFuel
levels of 100 and 300 W, and says it intends
Gottesfeld) have moved. The company has www.polyfuel.com to introduce commercial products in the near
partnered with DuPont to develop Nafionbased
DMFCs, and plans to commercialize a from independent research consultancy SRI
The California-based company – a spinoff future.
DMFC for cell phone applications in 2005. International – appears to be targeting commercial
product introductions by 2005. In late
Run DMFC – the key
The planned DMFC product would be about
the same size as a conventional cell phone battery,
but have a considerably longer operational reportedly ruled that a PolyFuel DMFC The two main barriers to economic DMFCs
2002 the US Department of Transportation technical challenges
time span between methanol cartridge replacements
as well as being more environmentally allowed on board commercial aircraft. This ini-
designed to power laptop computers could be are methanol crossover and slow anode kinetics.
• Methanol crossover is the diffusion of
acceptable.
tiated the process of regulatory acceptance for
methanol through the membrane from
DMFCs as an alternative to conventional bat-
the anode side to the cathode. This
teries in such applications.
reduces DMFC efficiency, primarily
because (1) the crossed-over methanol is
essentially wasted, and (2) the cathode’s
catalyst can be poisoned by the carbon
atoms in the methanol. This generally
limits methanol concentrations at the
anode compartment to around 2–5 wt%,
and may require recirculation of water
produced in the cathode compartment
back to the anode compartment in order
to keep the methanol dilute. Such constraints
generally limit the overall DMFC
efficiency to around 15–20% and the
power density to around 30 mW/cm 2 .
Methanol crossover losses can be 30%
or higher of the methanol fuel for some
DMFC membranes and design configurations.
• DMFC anode kinetics are slower than
those of PEM fuel cells running on
hydrogen. This means in turn that either
power densities are lower, or more expensive
platinum catalysts are needed. On
the other hand, DMFCs do not require
cooling plates or supplemental membrane
hydration systems, which could ultimately
make them more compact than hydrogen
PEM fuel cells.
SFC Smart Fuel Cell GmbH
DMFC that can power a laptop for an entire
The key to resolving methanol crossover lies
day on a single methanol cartridge.
in the membrane, whereas the key to faster
kinetics lies in the catalyst and the membrane-electrode
assembly (MEA). The development
of a DMFC membrane that is also
capable of operation at elevated temperatures
would have particularly profound significance,
by also enhancing kinetics while
reducing catalyst requirements. All are the
subjects of intense research.
November 2004
Fuel Cells Bulletin
15

FEATURE
Membranes
Nafion was a great advance in its day, but for
DMFCs there are better materials. Research
has focused on three types: perfluorinated
(which includes Nafion), partially fluorinated
and non-fluorinated.
Perfluorinated membranes currently cost
well upwards of US$800 per m 2 for DMFC
applications, which could be as much as $300
per kW of electric power output. The major
offerings are:
• Micro-reinforced perfluorinated ionomer
composite membranes – such as those
marketed by W.L. Gore under the trade
name Gore-Select. They are microporous
stretched PTFE filled with perfluorinated
ionomer. The thickness of the membrane
can be reduced to 20–35 µm. Another
membrane of this type is the Aciplex
range from Asahi Glass in Japan.
• Perfluorinated membranes/inorganic
particle composites – these are produced
by recasting Nafion solution and introducing
inorganic additives (such as
nanoporous, highly hydrophilic silica
particles) or heteropolyacids, such as
phosphotungstic acid or phosphomolybdenic
acid. The principal problem with
such membranes is the hydrosolubility
of the heteropolyacids. Improved performances
have been reported for DMFCs
in some cases because of reduced
methanol crossover, with a maximum
power density of 240 mW/cm 2 at 0.4 V.
However, the claims of reduced methanol
crossover for such membranes appear to
be controversial.
• Other Nafion-based composites – impregnating
a Nafion membrane with poly-(1-
methyl pyrrole) via in situ polymerization
using UV radiation or H 2 O 2 results in
reduced methanol permeation. Unfortunately,
the ionic conductivity was also
reduced. A plasma processing technique
has been devised to deposit a thin plasma
polymerized film on Nafion membranes,
to improve their barrier properties. The
use of layered membrane structures has
been investigated. Another approach
involves a three-layered laminar electrolyte
system, consisting of a dense, methanolimpermeable
protonic conductor sandwiched
between electronically insulating
layers.
Partially fluorinated membranes under
active investigation include the grafting of fluorinated
base polymer films by various techniques
with select materials. Other partially
fluorinated membranes under investigation
Figure 4. Cell phone with DMFC – external view (left) and exploded internal view (right).
include poly(α, β, β-trifluorostyrene) and
copolymers:
• Grafted ionomer membranes – this involves
bathing base polymer films in gamma radiation
to generate free radicals for subsequent
grafting. One developer claims to
have reduced methanol crossover relative to
Nafion 117 by up to 66%, adding that the
membrane can be manufactured at a small
fraction of the cost of Nafion.
• Ionomer membranes based on poly(α, β,
β-trifluorostyrene) and copolymers – these
have been pioneered by Ballard Power
Systems, which has developed several partially
fluorinated proton-conducting membranes
of sulfonated or phosphonated polymers
plus either poly(phenyl quinoxaline):
BAM 1G (2, 6-diphenyl 1,4-phenylene
oxide), BAM 2G, or a trifluoro styrene
based membrane, BAM 3G.
A variety of novel non-fluorinated ionomer
membranes have been reported in the general
literature. These include ionomers based on
phosphazene, arylene main chains, and
poly(benzimidazole) or PBI. One developer is
making impressive claims not only about reducing
methanol crossover, but also operating at
higher temperatures and methanol concentrations
– these are critical hurdles for DMFCs, if
they are to be economic in automobiles.
Catalysts and MEAs
Catalyst preparation and MEA manufacturing
techniques are major areas of research.
There are two general catalyst preparation
approaches:
• Impregnation – this is typically a deposition
step of the Pt and Ru precursors (for
example H 2 PtCl 6 , RhCl 3 , Pt(NH 3 ) 2 (OH) 2 ,
Ru 3 CO 2 , Pt(NH 3 ) 2 (NO) 2 etc.) followed
by a reduction step. Reduction can be via
the chemical reduction of the electrocatalyst
slurry in aqueous solution using N 2 H 4 ,
NaS 2 O 5 , NaS 2 O 3 or NaBH 4 , or via the gas
phase reduction of the impregnated carbon
black using a hydrogen gas stream. A drawback
of this procedure is that high dispersions
may not be achievable in the presence
of high metal loadings.
• Colloidal – the advantage here is higher
surface areas with high metal loading. The
main disadvantages are the complexity of
the preparation, the need for organic compounds/solvents,
and generally higher production
costs.
MEA manufacturing research includes experimentation
in:
• Incorporation of PTFE/carbon composite
ducts.
• Modification of the hydrophobichydrophilic
properties of the ionomer in
the electrocatalyst layer.
• Use of pore formers to increase the porosity
of the cathode active layer.
• Sputter deposition fabrication.
• Bipolar flow-field plates.
DMFC costs –
competitive in small
mobile applications
Based on a detailed review of patents and
technical papers, we have designed a DMFC
16
Fuel Cells Bulletin November 2004

RESEARCH TRENDS
Conventional Power Cost of DMFC power
Device power source output Base case Optimistic case
Cell phone Rechargeable 2 We 43% lower 82% lower
batteries
Small portable Internal combustion Under 22% lower 67% lower
generator engine 500 We
Automobile Internal combustion 75 kWe 188% higher 17% higher
engine
Source: Process Economics Program Report 243A, Direct Methanol Fuel Cells, to be published in October 2004
by SRI Consulting.
Table 1. Cost of DMFC power output compared to conventional power sources (on a $/kWe basis).
engineering concept for three mobile applications:
cell phones (Figure 4), small portable
generators, and automobiles. Some of these
applications may well be competitive with
conventional power systems (Table 1).
DMFCs for cell phones and small portable
generators are now below the cost of conventional
power technologies. For automobiles,
DMFCs are not yet cost-competitive, but
ongoing progress is dramatic, and the technology
is readily scalable. If environmental concerns
keep increasing the costs of conventional
engines and fuels, then it is only a matter of
time until DMFC automobiles become commercially
viable.
Convinced At least one company is. Parker-
Hannifin has begun selling its Vectrix DMFC
motor scooter on a pilot basis. The aim is to go
fully commercial in 2006.
For more information, contact: George Apanel,
SRI Consulting, 16945 Northchase Drive, Suite 1910,
Houston, TX 77060, USA. Tel: +1 281 876 6929,
Email:gapanel@sriconsulting.com,
Web:www.sriconsulting.com
Or contact: Eric Johnson, Atlantic Consulting,
Obstgartenstrasse 14, CH-8136 Gattikon, Switzerland.
Tel:+41 1 772 1079,Email:ejohnson@ecosite.co.uk
Research Trends
Performance of highly dispersed
Pt/C catalysts for PEM and DMFCs
P.K. Shen and Z. Tian: Electrochimica Acta
49(19) 3107–3111 (15 August 2004).
Zirconia-bridged hydrocarbon/
phosphotungstic acid hybrid materials
for high-temperature PEMFCs
J.-D. Kim and I. Honma: Electrochimica Acta
49(19) 3179–3183 (15 August 2004).
Preparation and characterization
of solution-cast Nafion ionomer
membranes
R.F. Silva, M. De Francesco and A. Pozio: Electrochimica
Acta 49(19) 3211–3219 (15 Aug. 2004).
Palladinized Nafion for DMFCs
Y.J. Kim et al.: Electrochimica Acta 49(19) 3227–
3234 (15 August 2004).
3D carbon nanotube network based
on hierarchical structure grown on
carbon paper, for PEMFC electrodes
X. Sun et al.: Chemical Physics Letters 394(4–6)
266–270 (21 August 2004).
Proton-conducting PDMS/metal
oxide hybrid membranes with
phosphotungstic acid, for hightemperature
PEMFCs
J.-D. Kim and I. Honma: Electrochimica Acta
49(20) 3429–3433 (30 August 2004).
XRD/XPS analysis of as-prepared
and conditioned DMFC array MEAs
R.R. Díaz-Morales et al.: J. Electrochem. Soc.
151(9) A1314–1318 (September 2004).
SOFC anodes based on Cu-Ni and
Cu-Co bimetallics in CeO 2
-YSZ
S.-I. Lee, J.M. Vohs and R.J. Gorte: J. Electrochem.
Soc. 151(9) A1319–1323 (Sep. 2004).
Temperature-dependent kinetics of
DMFC anode
J. Nordlund and G. Lindbergh: J. Electrochem.
Soc. 151(9) A1357–1362 (September 2004).
High-temperature, proton-conducting
polytetramethylene oxide/zirconia
hybrid membranes
J.-D. Kim and I. Honma: J. Electrochem. Soc.
151(9) A1396–1401 (September 2004).
LaNi(Fe)O 3
as SOFC cathode
H. Orui et al.: J. Electrochem. Soc. 151(9)
A1412–1417 (September 2004).
Effect of segregation to interface
on H 2
–H 2
O–Ni–YSZ electrode
performance
K. Vels Hansen, K. Norrman and M. Mogensen:
J. Electrochem. Soc. 151(9) A1436–1444 (September
2004).
Model and procedure to optimize
PEMFC internal structure and external
shape, for maximum net power
J.V.C. Vargas, J.C. Ordonez and A. Bejan: Int. J.
Heat & Mass Transfer 47(19/20) 4177–4193
(September 2004).
Preparation of Ni/YSZ anode for IT-
SOFCs by coating precipitation
F.H. Wang et al.: Materials Letters 58(24)
3079–3083 (September 2004).
Ionic, electronic transport in stabilized
β-La 2
Mo 2
O 9
SOFC electrolytes
I.P. Marozau et al.: Electrochimica Acta 49(21)
3517–3524 (1 September 2004).
Subsolidus phase equilibria in Al 2
O 3
–
CeO 2
–PbO and Al 2
O 3
–CeO 2
–RuO 2
systems
M. Hrovat et al.: Materials Research Bulletin
39(11) 1723–1728 (1 September 2004).
Hydrogen generation by hydrolysis
reaction of lithium borohydride
Y. Kojima et al.: Int. J. Hydrogen Energy 29(12)
1213–1217 (September 2004).
H 2
storage in wind turbine towers
R. Kottenstette and J. Cotrell: Int. J. Hydrogen
Energy 29(12) 1277–1288 (September 2004).
High-temperature membranes in
power generation with CO 2
capture
R. Bredesen, K. Jordal and O. Bolland: Chem.
Eng. & Processing 43(9) 1129–1158 (Sep. 2004).
November 2004
Fuel Cells Bulletin
17