The effects of carbon nanotube on the properties of graphite-carbon black-polypropylene composite for bipolar plate.
SUPERVISOR DECLARATION
"I declare that I have read this thesis and in my opinion this report is sufficient in terms
of scope and quality for the award of the degree of Bachelor of Mechanical Engineering
(Structure & Materials)"
Ｂ ｾ＠
Signature
..........................................
Supervisor
: DR. MOHD ZULKEFLI BIN SELAMAT
Date
:30MAY2013
DR. MOHD ZULKEFU BIN SELAMAT
Pensyarah Kanan
Fakulti Kejuruteraan Mel20Wcml),
iii.
High chemical and corrosion resistance,
IV.
Mechanical stability toward compression forces,
v.
Low permeability for hydrogen,
vi.
Low-cost material being processable with mass production techniques,
v11.
Low weight and volume, and
viii.
Recyclable materials
Two different kinds of materials have been used in the past: metallic and
graphitic. For mobile applications of fuel cells, the requirement of high power densities
at very low cost is difficult to fulfill, though the lifetime in terms of operational hours is
limited to several thousands. Here, stainless steel seems to be the material of choice the materials already being a mass product, its forming processes are well established in
the automotive industry. Thin metal sheets show sufficient mechanical strength. Two
sheets of thin and structured metal plates can be combined into a bipolar plate with flow
fields on both sides and cooling channels in between. For improving lifetime, a
corrosion-protective coating is typically required [6].
© Universiti Teknikal Malaysia Melaka
7
Bipolar plates are a very important component of a fuel cell. They can account
for 70-80% of the stack weight and up to 45% of the costs [7]. Bipolar plates have
multiple functions in a fuel cell. They are used to distribute the oxygen to the cathode
and the hydrogen to the anode, to manage water and heat from the reaction by removing
them, provides electrical contact between the plates to carry the current from cell to cell,
and to keep the reactants separated. Bipolar plates also need to be made from
lightweight, inexpensive materials that can be easily processed when producing bipolar
plates.
Bipolar plates can be made from many different materials, such as graphite,
metal, or polymer composites with carbon or metal conductive fillers [8]. Graphite is
one of the more traditional materials used to produce bipolar plates. The graphite bipolar
plates have very good thermal and electrical conductivity, excellent chemical
compatibility, and are corrosion resistant. Some problems with graphite bipolar plates
are the cost, from machining the gas flow channels into the plate and making the raw
graphite, and that graphite has low mechanical strength properties.
Metal bipolar plates have very good electrical and thermal conductivity, good
mechanical stability, and can be easily made. The main problem is they are not very
resistant to corrosion in the acidic conditions of a fuel cell. Aluminum, titanium, and
nickel bipolar plates need to be coated with a protective layer to resist corrosion.
Stainless steel is the only metal that has been studied that has the chemical stability to
resist corrosion.
Polymer composites are made from both thermosetting (phenolics, vinyl esters,
and epoxies) or thermoplastic (polypropylene, polyethylene) resins with different carbon
and metals conductive fillers. They are then compression or injection molded to create
bipolar plates with the gas flow channels, thus reducing the costs associated with
machining and other processing steps. Compression molding is the method of choice for
the production of bipolar plates because it has better precision, produces better electrical
and thermal conductivities, and is able to handle compounds with higher filler loadings.
© Universiti Teknikal Malaysia Melaka
8
However, bipolar plate production may eventually shift to injection molding because it
is one of the fastest and least expensive ways to produce plastics.
Table 1.3: Possible PEM fuel cells bipolar plate materials [3]
Types of Materials
Graphite
Properties
-Impregnate with polymer
-Highly conductive
-Brittle and thick
-High costs for machining flow path
Metals or Metal Alloys
-Stainless steel
- Al alloys
-Ni-Cr alloy
-Ti steel
-Highly conductive
-Corrosion problem
-High cost of machining flow path
Composite Materials
-Graphite/ Carbon composite
-Carbon/carbon composite
-Light and low cost
-Low conductivity compare to graphite and metal plate
Conductive Plastics
- Liquid Crystal Polymer (e.g. LCP)
- relative low conductivity
© Universiti Teknikal Malaysia Melaka
9
BiDOlar plates
No11-111t;tlid
ＭＱｾ
｟｣ ＢＧ ｟ ｾ ｟ Ｇ ＢＧ ｟ｩ Ｎ ｟ｾ＠
L ﾷＭ ﾷＭ ｟ＧＢｩ Ｍ :la:es
_,
S-.ahless Stee
ﾷ Ｎｾ
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... ·.
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Met.II p ates
[
:::wtA1
ｾ＠
ｾ＠
·.::.. tr· r.T
ｾ＠ .....ＢＡａＮＺ
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ＮＺ［ｾ
Ｑ＠
'Tr.arr_.,
'Nicl
"I declare that I have read this thesis and in my opinion this report is sufficient in terms
of scope and quality for the award of the degree of Bachelor of Mechanical Engineering
(Structure & Materials)"
Ｂ ｾ＠
Signature
..........................................
Supervisor
: DR. MOHD ZULKEFLI BIN SELAMAT
Date
:30MAY2013
DR. MOHD ZULKEFU BIN SELAMAT
Pensyarah Kanan
Fakulti Kejuruteraan Mel20Wcml),
iii.
High chemical and corrosion resistance,
IV.
Mechanical stability toward compression forces,
v.
Low permeability for hydrogen,
vi.
Low-cost material being processable with mass production techniques,
v11.
Low weight and volume, and
viii.
Recyclable materials
Two different kinds of materials have been used in the past: metallic and
graphitic. For mobile applications of fuel cells, the requirement of high power densities
at very low cost is difficult to fulfill, though the lifetime in terms of operational hours is
limited to several thousands. Here, stainless steel seems to be the material of choice the materials already being a mass product, its forming processes are well established in
the automotive industry. Thin metal sheets show sufficient mechanical strength. Two
sheets of thin and structured metal plates can be combined into a bipolar plate with flow
fields on both sides and cooling channels in between. For improving lifetime, a
corrosion-protective coating is typically required [6].
© Universiti Teknikal Malaysia Melaka
7
Bipolar plates are a very important component of a fuel cell. They can account
for 70-80% of the stack weight and up to 45% of the costs [7]. Bipolar plates have
multiple functions in a fuel cell. They are used to distribute the oxygen to the cathode
and the hydrogen to the anode, to manage water and heat from the reaction by removing
them, provides electrical contact between the plates to carry the current from cell to cell,
and to keep the reactants separated. Bipolar plates also need to be made from
lightweight, inexpensive materials that can be easily processed when producing bipolar
plates.
Bipolar plates can be made from many different materials, such as graphite,
metal, or polymer composites with carbon or metal conductive fillers [8]. Graphite is
one of the more traditional materials used to produce bipolar plates. The graphite bipolar
plates have very good thermal and electrical conductivity, excellent chemical
compatibility, and are corrosion resistant. Some problems with graphite bipolar plates
are the cost, from machining the gas flow channels into the plate and making the raw
graphite, and that graphite has low mechanical strength properties.
Metal bipolar plates have very good electrical and thermal conductivity, good
mechanical stability, and can be easily made. The main problem is they are not very
resistant to corrosion in the acidic conditions of a fuel cell. Aluminum, titanium, and
nickel bipolar plates need to be coated with a protective layer to resist corrosion.
Stainless steel is the only metal that has been studied that has the chemical stability to
resist corrosion.
Polymer composites are made from both thermosetting (phenolics, vinyl esters,
and epoxies) or thermoplastic (polypropylene, polyethylene) resins with different carbon
and metals conductive fillers. They are then compression or injection molded to create
bipolar plates with the gas flow channels, thus reducing the costs associated with
machining and other processing steps. Compression molding is the method of choice for
the production of bipolar plates because it has better precision, produces better electrical
and thermal conductivities, and is able to handle compounds with higher filler loadings.
© Universiti Teknikal Malaysia Melaka
8
However, bipolar plate production may eventually shift to injection molding because it
is one of the fastest and least expensive ways to produce plastics.
Table 1.3: Possible PEM fuel cells bipolar plate materials [3]
Types of Materials
Graphite
Properties
-Impregnate with polymer
-Highly conductive
-Brittle and thick
-High costs for machining flow path
Metals or Metal Alloys
-Stainless steel
- Al alloys
-Ni-Cr alloy
-Ti steel
-Highly conductive
-Corrosion problem
-High cost of machining flow path
Composite Materials
-Graphite/ Carbon composite
-Carbon/carbon composite
-Light and low cost
-Low conductivity compare to graphite and metal plate
Conductive Plastics
- Liquid Crystal Polymer (e.g. LCP)
- relative low conductivity
© Universiti Teknikal Malaysia Melaka
9
BiDOlar plates
No11-111t;tlid
ＭＱｾ
｟｣ ＢＧ ｟ ｾ ｟ Ｇ ＢＧ ｟ｩ Ｎ ｟ｾ＠
L ﾷＭ ﾷＭ ｟ＧＢｩ Ｍ :la:es
_,
S-.ahless Stee
ﾷ Ｎｾ
ｊ ＺＮｴＧＡ＠
... ·.
· =e'rli:
on.rx>.•t tri
Metals -
Met.II p ates
[
:::wtA1
ｾ＠
ｾ＠
·.::.. tr· r.T
ｾ＠ .....ＢＡａＮＺ
Ｂ｡Ｎ
ＮＺ［ｾ
Ｑ＠
'Tr.arr_.,
'Nicl