Untuk meningkatkan efektivitas membran sel bahan bakar dan menurunkan biaya produksi

Untuk meningkatkan efektivitas membran sel bahan bakar dan menurunkan
biaya produksi, beberapa membran hidrokarbon telah dikembangkan, diantaranya
adalah polieter sul-fon, polieter keton, akrilonitril butadiena stirena (ABS).
Membran dari kelompok polimer alifatis atau aromatis ini memiliki kelebihan
harganya yang murah, tersedia secara komersial, dan strukturnya memungkinkan
mampu menyimpan kelembaban sehingga dapat beroperasi pada suhu yang lebih
tinggi dibandingkan Nafion®. membran yang secara komerisal digunakan saat ini
adalah membrane Nafion®, namun, membran Nafion® masih memiliki kekurangan
yaitu harganya yang mahal dan terjadinya methanol crossover. Untuk
meningkatkan sifat-sifat membran elektrolit seperti konduktivitas proton dan
mengurangi permeabilitas metanol dilakukan penambahan kitosan yang
merupakan biopolimer yang memiliki gugus fungsional amin (-NH2) yang memungkinkan untuk dimodifikasi secara fisika dan kimia [8]
the disadvantage of PES is that it has low hydrophilic properties
Salah satu hambatan komersialisasi sel ini dikarenakan membran elektrolit menggunakan Nafion
bersifat permeabel terhadap metanol maupun etanol.
Membran fuel cell harus memiliki konduktivitas proton yang tinggi, memiliki dinding yang cukup kuat
untuk menghalangi laju alir reaktan dan stabil secara kimia maupun mekanik pada lingkungan sekitar
fuel cell [4]. Saat ini material membran yang digunakan secara komersil adalah Nafion® yang
dikembangkan oleh DuPont [4]. Nafion® merupakan suatu polimer organik berfasa padat berupa polyperfluorosulfonic-acid (Gambar 2). Nafion® mempunyai daya hantar proton atau konduktivitas proton
yang tinggi, sifat mekanik, kestabilan kimia dan termal yang baik sebagai syarat membran fuel cell.
Namun selain biaya produksi nafion sangat tinggi, nafion juga memiliki kelemahan yaitu memiliki sifat
permeabel yang cukup tinggi terhadap alkohol serta konduktivitas nafion menurun diatas suhu 90oC
[9,10].
Saat ini banyak dikembangkan material baru yang diharapkan dapat menggantikan fungsi Nafion® dalam
sel bahan bakar. Salah satu material yang banyak diteliti yaitu kitosan. Kitosan merupakan bahan kimia
multiguna berbentuk serat dan merupakan kopolimer berbentuk lembaran tipis, berwarna putih atau
kuning serta tidak berbau. Kitin yang telah terdeasetilasi sebanyak 65-95 % disebut kitosan (Gambar 3).
Kereaktifan kitosan disebabkan oleh adanya gugus amino bebas yang bersifat sebagai nukleofilik kuat
dan sekaligus kitosan bersifat polielektrolit, maka kitosan digolongkan sebagai Highly functional
biopolymer [7]. Elektrolit berbasis polimer merupakan komponen penting di banyak perangkat
elektrokimia. Elektrolit polimer berbiaya murah dan ramah lingkungan dari sumber terbarukan dapat
menjadi pengganti yang menjanjikan sebagai polimer sintetis untuk digunakan dalam perangkat
elektrokimia yang melibatkan pembangkit energi dan penyimpanan. Kitosan bersumber dari
polisakarida, telah banyak diteliti sebagai membran berbasis elektrolit polimer padat untuk fuel cell jenis
PEMFC [4]. Gugus fungsional -OH dan -NH2 pada kitosan memungkinkan dilakukan berbagai modifikasi
kimia untuk aplikasi tertentu. Penekanannya pada reaksi crosslinking kimia untuk meningkatkan
stabilitas mekanik dan kimia, dan modifikasi kimia untuk kemungkinan menghasilkan pertukaran ion dan
meningkatkan konduktivitas ionik yang merupakan persyaratan bagi membran fuel cell [3,4]. Tujuan dari
penelitian ini adalah membuat membran kitosan sulfonat dari kitosan dengan cara metode sulfonasi
menggunakan pereaksi asam sulfosalisilat. Membran yang dibuat dikarakterisasi sesuai spesifikasi yang
memenuhi standar untuk fuel cell khususnya DEFC.
.
To improve the effectiveness of fuel cell membranes and reduce production costs, several hydrocarbon
membranes have been developed, including sulphon polyether, ketone polyether, styrene acrylonitrile
butadiene (ABS). Membranes from this group of aliphatic or aromatic polymers have the advantage of
being cheap, commercially available, and allowing their structure to store moisture so that they can
operate at higher temperatures than Nafion®. membranes that are commercially used today
is the Nafion® membrane, however, the Nafion® membrane still has shortcomings namely the high price
and the occurrence of methanol crossover. To improve the properties of electrolyte membranes such as
proton conductivity and reduce the methanol permeability, the addition of chitosan which is a
biopolymer that has a functional group amine (-NH2) which allows
allow to be modified physically and chemically
The materials used for fuel cell membrane must have a high proton conductivity, a strong enough wall
to block the reactant flow rate, and be chemically or mechanically stable in the environment around the
fuel cell. To improve the effectiveness of fuel cell membranes and reduce production costs, several
hydrocarbon membranes have been developed, including polyethersulfone. Membrane from this
polymer has the advantage of being cheap, commercially available, and allowing their structure to store
moisture so it can operate at higher temperatures but it has low hydrophilic properties. Chitosan, as a
biopolymer that has -OH and -NH2 functional groups, can be used for various chemical modifications
including to increase mechanical and chemical stability and modification to the possibility of producing
ion exchange and increasing ionic conductivity which is a requirement for fuel cell membrane. The
purpose of this study is to review the use of chitosan and polyethersulfone as the basic mechanical
support.
the purpose of this paper is to review the use of PES which has been modified with chitosan
This paper reviews structure and property of chitosan with respect to its applications in fuel cells.
The purpose of this research is to make chitosan sulfonate membrane from chitosan by means of the
sulfonation method using sulfosalicylic acid reagents. Membranes made are characterized according to
specifications that meet the standards for fuel cells, especially DEFC.
Therefore, in order to verify the feasibility of our current strategy and also based on our previous
studies, PVDF electrospun nanofiber mat was used as the basic mechanical support in this work
In our previous work, polyvinylidene fluoride (PVDF) has been incorporated into a nanofiber mat and
then fabricated high-performance proton exchange membranes, due to its high electrospinnability,
excellent mechanical properties, high thermal and chemical stabilities [25, 26]. Recently, chitosan (a
cost-effective, eco-friendly and easily quaternized biopolymer) also has been used to prepare a series of
quaternized chitosan (QCS)-based composite AEMs [27–29]. The results showed that QCS with
quaternization degree beyond 40% exhibited high ionic conductivity, but it can not be used as an AEM
alone because of its strong hydrophilicity resulted from numerous hydrophilic groups (e.g. –OH, –NH2
and –NR3 þ). Therefore, in order to verify the feasibility of our current strategy and also based on our
previous studies, PVDF electrospun nanofiber mat was used as the basic mechanical support in this
work. After simply and physically coating with SiO2, a silane coupling agent with quaternary ammonium
groups was subsequently grafted onto the surface of silica coated PVDF (SiO2@PVDF) to form a highconcentration cationized surface. Finally, super-hydrophilic QCS, which is even difficult to be a freestanding film in its wet state, was selected to impregnate the quaternized SiO2@PVDF nanofiber mat for
the purpose of proving the role of ultra-strong mechanical support of this designed mat. The
microstructure, mechanical properties, dimensional stability, ion exchange capacity, conductivity, single
cell performance and durability were performed and discussed
Chitosan biopolymer for fuel cell applications
Fuel cell is an electrochemical device which converts chemical energy stored in a fuel into electrical
energy. Fuel cells have been receiving attention due to its potential applicability as a good alternative
power source. Recently, cost-effective and eco-friendly biopolymer chitosan has been extensively
studied as a material for membrane electrolytes and electrodes in low to intermediate temperature
hydrogen polymer electrolyte fuel cell, direct methanol fuel cell, alkaline fuel cell, and biofuel cell. This
paper reviews structure and property of chitosan with respect to its applications in fuel cells. Recent
achievements and prospect of its applications have also been included.
Composite membranes from quaternized chitosan reinforced with surface-functionalized PVDF
electrospun nanofibers for alkaline direct methanol fuel cells
In order to obtain a dual-functional nanofiber framework that could simultaneously serve as an ultrastrong reinforcing substrate and a fast ion transport medium, herein, silica coated poly(vinylidene
fluoride) (SiO2@PVDF) electrospun nanofiber mat was firstly prepared using a universal polydopamineassisted sol-gel method. After grafting with dense quaternary ammonium groups, quaternized
SiO2@PVDF (QSiO2@PVDF) was yield. This mat with densely cationized surface can not only provide a
reliable mechanical support for superhydrophilic quaternized chitosan (QCS), but also significantly
improve the ionic conductivity of the whole system. The resulting QCS impregnated membrane exhibits
satisfactory wet strength of as high as 11.9 MPa while pure QCS is hardly self-supporting. Moreover, the
surface high-concentration cationic groups can establish channel-like ion transport pathways with the
aid of 1D continuous nanofibers, thus obtaining high ionic conductivity of 0.041 S cm 1 (80 �C), which is
about 1.3 times higher than that of pure QCS. The single alkaline fuel cell using this membrane
demonstrates a maximum power density of 98.7 mW cm 2 . Therefore, this relatively independent
design of mechanically support fiber core and high-concentration ion conduction surface provides a new
methodology for fabricating high-performance anion exchange membranes
Self-humidifying novel chitosan-geopolymer hybrid membrane for fuel cell applications
Novel, eco-friendly organic-inorganic hybrid, self-humidifying proton exchange membrane (PEM) series
from chitosan (CS) were prepared by solvent-casting technique wherein heptanedioic acid (HA) is used
as crosslinker and geopolymer (GP), an inorganic aluminosilicate material as the filler. FTIR, solid state
NMR, SEM and XRD analysis revealed the formation of super-compatible CS-HA-GP hybrid membranes.
Good self-humidification, appreciable proton conductivity, thermal stability and porosity were exhibited
by the membranes. Thermokinetic behaviour of the membranes was studied using Broido’s
approximation method and the activation energy for different thermal degradation stages was deduced.
The hybrid membrane with a concentration of 1.5 wt% of the crosslinker and 0.5 wt% of the filler
showed excellent water retention, considerable porosity, highest proton conductivity of 4.12 × 10−3
Scm-1, appreciable thermal, mechanical as well as oxidative stability and high activation energy, is
considered as the optimum composition. The above results suggest the suitability of these novel hybrid
membranes as substitutes for Nafion in fuel cells
Chitosan/graphene complex membrane for polymer electrolyte membrane fuel cell: A molecular
dynamics simulation study
Chitosan has been considered attractive in polymer electrolyte membrane fuel cells (PEMFCs) due to its
excellent film forming and fuel barrier properties. Reflecting the limitation of its low proton
conductivity, various materials were used to improve the proton conductivity of chitosan, through
combination with inorganic materials like graphene oxide. We present an ideal molecular model for bionanocomposites and their mechanism of proton conductivity in PEMFCs. In this study, the diffusion
behavior of hydronium ions in chitosan/graphene complex systems at various temperatures,
concentrations and pH values were studied systematically using 3 ns long molecular dynamics (MD)
simulations with an aim to provide the mechanisms of proton conductivity of chitosan/graphene
composite at an atomistic scale. Various amounts of water content (10%, 20%, 30% and 40%), pH values
(achieved by adjusting the protonation degree of amino groups of chitosan by 20%, 40%, 60%, 80% and
100%) and numbers of graphene sheets (1, 2, and 3) were considered during MD simulations at 4
temperatures (298 K, 320 K, 340 K and 360 K). Our results indicated that the chitosan system containing
40% water was the most suitable polymer electrolyte membrane and temperature was a key factor
affecting diffusion proton. Adding graphene to the chitosan system and adjusting the pH values of
chitosan were