Sel Bahan Api Metanol (DMFC) telah menjadi salah satu jenis tenaga yang boleh
diperbaharui disebabkan oleh metanol yang boleh sentiasa dihasilkan. Ianya juga
ketumpatan kuasa yang tinggi. Dunia sedang menghadapi krisis tenaga dan DMFC ini
berpotensi untuk menjadi salah satu penyelesaian utama kepada masalah tersebut. Kini,
DMFC didapati boleh diaplikasikan pada peralatan elektrik mudah alih seperti
computer riba, telefon bimbit dan sebagainya dan aplikasi ini lebih mencadangkan
untuk dioperasi pada suhu bilik. Oleh itu, kajian mengenai DMFC yang beroperasi
pada suhu bilik (25 ⁰C) dalam sistem kumpulan telah dijalankan bagi kepekatan
metanol yang berlainan. Maksima arus elektrik yang dicatatkan oleh sistem tersebut
adalah bagi 4M kepekatan metanol, iaitu 0.0021 mA. Teknik Elektrokimia Impedans
Spectroskopi (EIS) telah digunakan untuk mendapatkan rintangan dalaman pada anod
bagi pelbagai kepekatan metanol. Plot Nyquist telah diplot and rintangan dalaman
didapati mengurang apabila kepekatan metanol mengurangkan. Model Litar Setaraf
(ECM) telah dikaji untuk menunjukkan ciri-ciri sistem eletrokimia dan pengesahan
data eksperimen. Dengan ini, kajian tentang rintangan dalaman, rintangan bagi tindak
balas electro-pengoksidaan metanol, rintangan bagi tindak balas eletro-pengoksidaan
carbon monoksida yang terjerap dan unsur kapasitif telah dilakukan. Jumlah rintangan
dalaman yang paling kurang telah ditentukan oleh 3M kepekatan metanol iaitu 221.70
Ω.cm2 dengan jumlah sisa persegi 0.00049 manakala yang tertinggi adalah 5M
kepekatan metanol iaitu 1027.21 Ω.cm2 dengan sisa persegi 0.0080. Hasil kajian ini
telah menunjukkan ECM yang dicadangkan adalah sesuai dengan data eksperimen.
Selain itu, pelbagai voltan luaran telah diaplikasikan pada sistem tersebut and
implikasinya terhadap rintangan dalaman telah dikaji bagi kepekatan metanol yang
berlainan. Hasil kajian telah menunjukkan bahawa rintangan dalaman menurun
semasa aplikasi voltan luaran pada sistem meningkat. Eksperimen bagi 3M kepekatan
metanol telah berulang untuk mengkaji konsisten data eksperimen. Dari seluruh kajian
ini, impak kepekatan metanol pada arus elektrik dan rintangan dalaman telah
dibentangkan. Kajian ini telah menunjukkan 3M and 4M kepekatan metanol adalah
kepekatan yang paling sesuai digunakan dalan sistem tersebut disebabkan olen arus
elektrik yang tinggi dan jumlah rintangan dalaman yang rendah.
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Direct Methanol Fuel Cell (DMFC) is emerging as a new source of renewable energy
due to the renewable methanol source and its high power density. The global is facing
energy crisis and DMFC might be one of the key solution to this problem. Currently,
DMFC was found that it has the ability to be applicable on various portable auxiliary
and off-grid power applications such as laptop computers, two-way radios and mobile
phones and all these were preferable to be at ambient temperature. Therefore, DMFC
operating at room temperature (25 ⁰C) in a single batch system was investigated in
this study for various methanol concentration. The maximum current for the system
was recorded to be at 4M methanol concentration which was 0.0021mA.
Electrochemical Impedance Spectroscopy (EIS) study was performed to determine the
internal resistance at the anode electrode for various methanol concentration with no
external voltage supplied. Nyquist Plot was presented and it was found that the
impedance decreased with the methanol concentration. Equivalent Circuit Model
(ECM) was then developed to represent the behavior of the electrochemical system
and verified the experimental data by fitting it with the empirical data. The IR
resistance, methanol electro-oxidation reaction resistance, electro-oxidation reaction
resistance of adsorbed CO and the capacitive element were investigated. It was found
that 3M gave the lowest total internal resistance and 5M gave the highest which were
221.70 Ω.cm2 and 1027.21 Ω.cm2, with residual sum square, x2 of 0.00049 and 0.0080
respectively. It was found that the experimental data is fitted well to the empirical
model generated from the proposed ECM. The study was followed by investigating
the effect of different external voltage supplied to the system on the impedance of the
system. It was found that the impedance decreased as the applied voltage increased for
respective methanol concentration. Since 3M methanol concentration gave the lowest
total impedance value with high current profile, experiment was repeated for this
methanol concentration to study the consistency of experimental data. It was found
that the data was quite consistent despite the slight deviation. This research clearly
demonstrated the impedance of a single batch system operating at room temperature
for various methanol concentration as well as for various external voltage supplied.
Through this experiment, it was found that 3M and 4M methanol concentration were
the optimum concentration to be used for this system due to their relatively high
current profile as well as low total impedance.
A study of methanol concentration of a single chamber direct methanol fuel cell via electrochemical impedance spectroscop / Siew Seok Li