Solid polymer electrolyte based on methyl cellulose (MC)-lithium triflate (LiCF3SO3) plasticised with ethylene carbonate (EC) was prepared using solution cast technique. The X-ray diffraction (XRD) studies proved that the amorphous nature of the electrolyte systems was increases due to the addition of salt and plasticiser. The improved surface morphology of plasticised polymer system ensures it has good electrode-electrolyte contact during performance testing. The polymer electrolyte was found to have high thermal stability indicating that the electrolyte can be used at higher temperature. The ionic conductivity increased up to 1.24 x 10-4 S cm-1 at optimum amount of EC plasticiser associated to the effect of plasticiser that initially leads to the formation of Li+-EC complex. Consequently, it reduces the fraction of polymer-Li+ complex which contributes to the increase of the segmental chain flexibility in the plasticized system. Temperature dependent studies indicate ionic conductivity increase due to the temperature increase and is in line with Arrhenius behaviour pattern. An activation energy of 0.26 eV at highest conductivity sample was obtained. The addition of plasticiser lowers the activation energy thus increasing the ion mobility of the system and contributing to ionic conductivity increment. The plasticization method is a promising means to dealing with the solid polymer electrolyte problem and producing electrolytes that meet the needs of electrochemical devices.
Magnesium-based polymer gel electrolytes consist of magnesium triflate (MgTf) salt, a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) solvents as well as cellulose acetate as a polymeric agent were prepared via direct dissolution method. The highest ionic conductivity obtained for MgTf-EC:DEC(1:1) liquid electrolytes was 2.66 x 10-3 S cm-1 and enhanced to 2.73 x 10-3 S cm-1 with the addition of cellulose acetate. These results were in agreement with the activation energy obtained with the lowest value of 0.11. The best explanation on the enhancement in ionic conductivity of PGE is due to the “breathing polymeric chain model”. The plots of conductivity-temperature shown to obey an Arrhenius rule. The electrical properties of the sample with the highest conductivity were analyzed using electrical permittivity-based frequency and temperature dependence in the range of 100 Hz - 1 MHz and 303-373K, respectively. The variation in dielectric permittivity (εr and εi) as a function of frequency at different temperatures exhibited decays at higher frequencies and a dispersive behavior at low frequencies. Based on the observed electrical properties, it can be inferred that this polymer gel electrolyte could be a promising candidate as an electrolyte in electrochemical devices.
Zaidatul Salwa Mahmud, Siti Nor Hafiza Mohd Yusoff, Nur Hamizah Mohd Zaki, Mohamad Fariz Mohamad Taib, Mohamad Kamil Yaakob, Oskar Hasdinor Hassan, et al.
A free-standing film consisting of 49% PMMA grafted-natural rubber electrolytes was prepared. Potassium hydroxide (KOH) and propylene carbonate (PC) was added to the preparation and the properties of the electrolytes measured using complex impedance analysis at various temperatures. The addition of plasticiser in alkaline polymer electrolyte gives rise to the ionic conductivity up to 2.647 x 10-6 S cm-1 at composition consisting of 50wt.% of PC. The dielectric properties of the GPEs were studied and the relaxations at higher frequencies appear in both imaginary and real part of the permittivity. These relaxations are related with the interface ion polarisations at the polymer-electrode interface and segmental motion of the polymer electrolyte molecular chains. The influence of the impedance spectra on temperature was studied. Results showed rising temperature increased conductivity, top frequency (f*), relative dielectric constant (εr) and geometrical capacitance (Cg) due to the mobility of free ion carriers.
io-electricity generation by Microbial Fuel Cell (MFC) has gained considerable attention due to
its integration with wastewater treatment such as Palm Oil Mill Effluent (POME). Investigation
into pH effect and determination of optimal pH value ranges growth for acidogenic, acetogenic
and methanogenic by natural mixed culture
electroactive bacteria (exoelectrogens) growth
in original non-Deoxygenated Mixed POME
(nDMP) and Deoxygenated Mixed POME (DMP)
in MFC was carried out. Current generation,
power generation and maximum power were
also monitored. Experimental results show that
exoelectrogens in nDMP with pH 6.8 yielded the
highest current generation of 61.51 mAm-2 and
maximum power of 17.63 mWm-2. Overall, nDMP
substrates with 3 pH ranges (5.5, 6.8 and 8.0)
showed equal potential to generate power that is
higher than DMP substrates. Comparison carried
out for inter DMP substrates demonstrated that
DMP with pH 6.8 and DMP with pH 8.0 showed equal potential to generate power, but not for DMP with pH 5.5. Subsequently, nDMP with pH 6.8 and
nDMP with pH 8.0 showed equal potential for higher maximum power compared to nDMP with pH
5.5 and DMP substrates. This finding indicates that mixed microbial communities in DMP substrate
are dominant with obligate anaerobic exoelectrogens bacteria which have less capability to generate
electricity compared to nDMP substrate that was dominated by the aerotolerant and/or facultative
anaerobic exoelectrogens bacteria.