Our advanced nonwoven materials play an
important role in enabling emerging technologies; fuel cells are a
prime example of this. TFP has been developing gas diffusion layer
(GDL) materials for over 30 years, building the capability,
expertise and capacity to meet the forecast growth in fuel cell
TFP has been developing and optimising material for
fuel cell GDLs since 1988, working alongside some of the leading
companies in the industry. This long term
commitment to fuel cell development and growth has facilitated a
comprehensive understanding of the necessary material
characteristics to achieve a high performance GDL substrate.
The result is a range of carbon veils and mats which
can be tailored to suit the requirements of both stationary and
portable fuel cell systems. To date our nonwovens have been used
successfully as GDLs in proton electrolyte membrane (PEMFC),
phosphoric acid (PAFC) & direct methanol (DMFC) fuel cells.
WHAT IS A FUEL CELL?
A fuel cell is an electrochemical device that
combines hydrogen (or hydrogen-rich) fuel and oxygen to produce
electricity, heat and water. It is much cleaner and more efficient
than an internal combustion engine (ICE) as it does so without
burning the fuel. Essentially more of the fuel is converted into
electricity and less into heat.
The active components of a fuel cell are combined in
the membrane electrode assembly (MEA), which is composed of an
anode, a cathode and an electrolyte membrane. Hydrogen fuel is
supplied to the anode, and oxygen to the cathode, via the bipolar
plates. The anode is coated with a catalyst which accelerates the
conversion of hydrogen to protons and electrons. The electrolyte
membrane is selective to protons only, allowing them to pass
through to the cathode. The electrons must move via an external
circuit generating an electrical current and excess heat. At the
cathode the protons, electrons and oxygen combine to generate a
water molecule, the only by-product of the process.
Individual fuel cells can be compiled to form stacks,
which in turn can be combined into larger systems. This means that
fuel cell systems vary significantly in both size and power,
ranging from portable systems for transportation to large scale
installations that provide electricity for high energy demand
applications such as schools and hospitals.
THE GDL AND ITS FUNCTION
TFP's carbon nonwoven is widely utilised as a
substrate for the GDL, a critical component of the MEA which is the
heart of the fuel cell. The GDL forms the basis of both the anode
and cathode, and is responsible for water management, the transport
of reactants, electricity and heat, as well as providing structural
support to the assembly.
The GDL must be both electrically and thermally
conductive to allow current flow, and have a suitable pore
structure to optimise mass transport. The structure must also
exhibit the correct balance of hydrophobicity, to manage the
movement of water and gases in the MEA. This latter property is
critical to the efficient operation of the cell; if the GDL is too
wet during operation the by-product (water) is not being
effectively removed, flooding may occur and reactant gas movement
is impeded. Equally, if the GDL is too dry then the membrane will
dry out causing higher resistance. In both cases the performance of
the cell is reduced.
The properties of our carbon nonwovens fulfil the
performance requirements and material characteristics needed from a
GDL substrate and are widely used as such. These attributes
POROSITY - Our veils are highly porous and the pore
structure can be tailored to accommodate different types of
carbonaceous filler and post treatments.
TFP's carbon nonwovens have high in-plane & through-plane
electrical and thermal conductivity, so effective electrical
conduction and heat transfer between the catalyst and the current
collector plates can occur.
RESISTANCE - TFP's range of carbon mats and veils inherently
exhibit good chemical & corrosion resistance to reactant
AREA - Our materials are highly porous and provide a large
surface area. This aids optimum control of reactant gas and water
movement during operation, helping to maintain effective mass
transport and efficient cell performance.
DURABILITY - Our
nonwovens provide excellent durability & strength. They exhibit
controllable and repeatable compressibility. This is important both
in stack assembly to accommodate thickness variation in cell stack
components, as well as during operation to adapt to the thermal
expansion seen in larger fuel cell stacks.
EVEN SURFACE -
The superior even fibre distribution characteristic of our
nonwovens provides a suitable architecture for application of a
smooth microporous layer coating.
Contact us for more
information about our carbon nonwovens and their use as GDL