Sains Malaysiana 40(7)(2011): 695–700

Comparative Studies on Plasticized and Unplasticized Polyacrylonitrile (PAN) Polymer Electrolytes Containing Lithium and Sodium Salts

(Kajian Perbandingan ke atas Elektrolit Polimer Berasaskan Poliakrilonitril (PAN) dengan Agen Pemplastik dan Tanpa Agen Pemplastik yang Mengandungi Garam Litium dan Garam Natrium)

K. B. Md. Isa, L. Othman & Z. Osman*

Physics Department, University of Malaya, 50603 Kuala Lumpur, Malaysia

Received: 23 October 2009 / Accepted: 20 September 2010

ABSTRACT

Polymer electrolytes based on polyacrylonitrile (PAN) containing inorganic salts; lithium triflate (LiCF3SO3) and sodium triflate (NaCF3SO3) and ethylene carbonate (EC) as plasticizer were prepared using solvent casting technique. In this study, five systems of plasticized and unplasticized polymer electrolyte films i.e. PAN-EC, PAN-, PAN- PAN-EC- and PAN-EC- systems have been prepared. The structural and morphological properties of the films were studied using infrared spectroscopy and scanning electron microscopy (SEM) while the conductivity study was done by using impedance spectroscopy. The infrared results revealed that interaction had taken place between the nitrogen atoms of PAN and Li+ and Na+ ions from the salts. SEM micrographs showed that the plasticized film, PAN-EC- has bigger pores than PAN-EC-3 film resulting in the film containing salt being more conductive. On addition of salts and plasticizer, the conductivity of pure PAN increases to three orders of magnitude. The plasticized film containing salt has a higher conductivity compared to that containing salt. This result showed that the interaction between Li+-ion and the nitrogen atom of PAN was stronger than that of Na+-ion. The conductivity-temperature dependence of the highest conducting film from each system follows Arrhenius equation in the temperature range of 303 to 353 K. The conductivity-pressure study in the range of 0.01 - 0.09 MPa showed that the conductivity decreased when pressure was increased. This can be explained in term of free volume model.

Keywords: Conductivity; lithium triflate; plasticizer; polyacrylonitrile; sodium triflate

ABSTRAK

Elektrolit polimer berasaskan poliakrilonitril (PAN) yang mengandungi garam tak organik; litium triflat (LiCF3SO3) dan natrium triflat (NaCF₃SO₃), etilena karbonat (EC) sebagai agen pemplastik telah disediakan dengan kaedah tuangan larutan. Dalam kajian ini, lima sistem elektrolit polimer filem yang mengandungi agen pemplastik dan tidak mengandungi agen pemplastik iaitu PAN-EC, PAN-, PAN- PAN-EC-dan PAN-EC- telah disediakan. Sifat-sifat struktur dan morfologi filem telah dikaji dengan menggunakan spektroskopi inframerah dan mikroskop elektron imbasan (SEM) manakala kekonduksian dikaji dengan menggunakan spektroskopi impedans. Keputusan spektroskopi inframerah menunjukkan berlakunya interaksi di antara atom nitrogen daripada PAN dengan ion Li+ dan ion Na+ daripada garam. Mikrograf SEM menunjukkan bagi filem yang mengandungi agen pemplastik, filem PAN-EC- mempunyai liang yang lebih besar daripada filem PAN-EC- menyebabkan filem yang mengandungi lebih konduktif. Dengan penambahan garam dan agen pemplastik, kekonduksian bagi filem PAN tulen meningkat sebanyak tiga turutan magnitud. Filem yang mengandungi agen pemplastik dengan garam NaCF3SO3 mempunyai nilai kekonduksian lebih tinggi daripada yang mengandungi garam . Ini menunjukkan interaksi di antara ion Li+ dengan atom nitrogen daripada PAN adalah lebih kuat daripada ion Na+. Kajian kebergantungan kekonduksian terhadap suhu bagi filem yang mempunyai kekonduksian tertinggi daripada semua sistem menunjukkan ia mematuhi persamaan Arrhenius dalam julat suhu daripada 303 K hingga 353 K. Kajian kebergantungan kekonduksian terhadap tekanan dalam julat 0.01 - 0.09 MPa menunjukkan kekonduksian menurun dengan tekanan. Keputusan ini boleh diterangkan dengan model isipadu bebas.

Kata kunci: Agen pempalstik; kekonduksian; litium triflat; natrium triflat; poliakrilonitril

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*Corresponding author; email: zurinaosman@um.edu.my