This document summarizes research on solid polymer electrolytes made of carboxyl methylcellulose (CMC) doped with oleic acid (OA). The highest ionic conductivity of 2.11 x 10-5 S cm-1 was found for a sample with 20 wt.% OA. Analysis showed increasing ionic mobility and diffusion coefficient with higher OA concentration. Transference number measurements confirmed the samples were proton conductors, with higher values for cation mobility and diffusion compared to anions. The conductivity could potentially be improved by adding a plasticizer, though it remains lower than other polymer electrolytes currently.

1. Proton conducting polymer electrolytes of
carboxyl methylcellulose doped Oleic acid
M.N. Chai and M.I.N. Isa
Department of Physical Sciences, Faculty of Science & Technology, University
Malaysia Terengganu, 21030 Kuala Terengganu, Terengganu, Malaysia
ABSTRACT
Solid polymer electrolytes (SPE) of carboxyl methylcellulose (CMC) as the polymer host and oleic acid (OA) as a dopant were prepared by the solution casting technique.
The films obtained were transparent and no phase separation. The highest ionic conductivity, σ, was found to be 2.11 x 10-5 S cm-1 at room temperature (303 K) for sample
CMC-OA 20 wt. %. The ionic mobility and diffusion coefficient that was calculated in this work is in good agreement with the increment of weight percent (wt. %) of acid
concentration. The value of cation of diffusion coefficient and ionic mobility was higher than value of anion. Thus, the results proven that the present samples were proton
conductor.
INTRODUCTION RESULT AND DISCUSSION
Over the past year, the electrochemical power was obtained by using liquid
2.50E-05 -3.5
electrolyte due to its conductivity. Unfortunately, this liquid electrolyte gives a lot of OA-0
OA-5
problem such as leakage, reaction with electrode, and poor electrochemical -4.0
2.00E-05
Conductivity (S cm-1)
OA-10
Log conductivity, σ
stability, which makes it unsuitable for use in electro-chemical devices [1]. In the
-4.5 OA-15
world of modern technologies, commercial batteries represent a large number of 1.50E-05 OA-20
toxic and hazardous materials which brings harm to the environment and human -5.0 OA-25
health [2]. 1.00E-05 OA-30
-5.5
In this study, a proton-conducting solid polymer electrolyte or SPEs is presented to 5.00E-06
-6.0
overcome this problem. Electrolyte from cellulose or cellulose derivative is chosen.
CMC is a naturally occurring polysaccharide and the most abundant organic 0.00E+00 -6.5
substance on the earth. Due to the abundance, low cost and easier process ability, 0 10 20 30 2.5 2.7 2.9 3.1 3.3
Concentration of OA (wt. %) 1000/T (K-1)
so CMC is chosen in this research [3].
Figure 1 Variation of conductivity as a Figure 2 The temperature
function of salt content at room dependence for conductivity of
METHODOLOGY temperature CMC-OA electrolyte
Table 1 Ionic mobility and diffusion coefficient of cations and anions
START Sample tion μ+ x 10-10 μ- x 10-10 D+ x 10-11 D- x 10-11
(cm2V-1s-1) (cm2V-1s-1) (cm2s-1) (cm2s-1)
OA-5 0.65 0.82 0.44 0.21 0.12
Sample Preparation OA-20 0.76 45.90 14.50 12.00 3.79
OA-30 0.74 3.40 1.20 0.89 0.31
1 g of CMC + 33 ml of distilled water
Phase 1 OA- 30
2850
Different wt.% of OA + 66 ml of ethanol 2920
OA- 25
Solution Casting Technique
OA- 20
% Transmitance
OA- 15
Sample Characterization
OA- 10
Phase 2 Electrical Fourier Transference
Impedance Transform Number OA- 5
Spectroscopy Infrared (FTIR) Measurement
(EIS) Spectroscopy (TNM)
OA- 0
Data Analysis 1597
3100 2400 1700 1000
Wavenumber (cm-1)
End
Figure 3 FTIR spectrum of the sample in the region between
1000 and 3100 cm-1
CONCLUSION REFERENCES
The CMC-OA biopolymer electrolyte obtained the highest conductivity of 1. Idris, N.K., Nik Aziz, N.A., Zambri, M.S.M., Zakaria, N.A. & Isa, M.I.N. 2009.
2.11 x 10-5 S cm-1. By using Rice and Roth model, conductivity of CMC–OA Ionic conductivity studies of chitosan- based polymer electrolytes doped with
biopolymer electrolyte is not only caused by the increase in the concentration but adipic acid. Ionics 15: 643-646.
also by the at room temperature for sample OA-20 with OA concentration of 20 wt. 2. Fonseca, C.P., Rosa, D.S., Gaboardi, F. & Neves, S. 2006. Development of a
%. increase in ionic mobility and diffusion coefficient. From the TNM, it is proven biodegradable polymer electrolyte for rechargeable batteries. Journal of power
that the sample is a proton conductor where the value of μ+ and D+ is found to be source 155: 381-384.
higher than the value of μ- and D-. Thus, this prove that the present samples were 3. Siddhanta, A.K., Prasad, K., Meena, R., Prasad, G., Mehta, G.K., Chhatbar,
proton conductor. The conductivity is still low compared to the current conductivity M.U., et al. 2009. Profiling of cellulose content in Indian seaweed species.
based on polymer, it can be enhanced with the addition of plasticizer. Bioresource Technology 100: 6669-6673.
ACKNOWLEDGMENT
The authors would like to thank the Department of Physical Sciences under the Faculty of Science and Technology, University Malaysia Terengganu, for the help and
support given for this work.