Sains Malaysiana 47(9)(2018): 2091–2098

http://dx.doi.org/10.17576/jsm-2018-4709-17

Kesan Garam Litium Nitrat terhadap Sifat Elektrokimia Karboksimetil Kitosan

(The Effect of Lithium Nitrate towards Electrochemical Properties of Carboxymethyl Chitosan)

N.N. MOBARAK*, F.N. JANTAN, N.A. DZULKURNAIN, A. AHMAD & M.P. ABDULLAH

School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor Darul Ehsan, Malaysia

Diserahkan: 31 Mac 2018/Diterima: 17 Mei 2018

ABSTRAK

Karboksimetil kitosan menunjukkan potensi untuk digunakan sebagai polimer induk bagi aplikasi elektrolit polimer pepejal. Kesan garam litium nitrat terhadap sifat elektrokimia elektrolit polimer pepejal berasaskan karboksimetil kitosan telah dijalankan. Elektrolit polimer pepejal berasaskan karboksimetil kitosan disediakan melalui teknik pengacuan larutan dengan nisbah garam litium nitrat (LiNO₃) yang berbeza. Pencirian filem telah dijalankan dengan menggunakan spektroskopi inframerah transformasi Fourier-pantulan penuh kecil (ATR-FTIR) dan Spektroskopi Impedans Elektrokimia (EIS) bagi penentuan interaksi kimia dan sifat elektrokimia polimer elektrolit tersebut. Spektrum ATR-FTIR menunjukkan ion litium cenderung untuk berinteraksi dengan kumpulan karbonil dan kumpulan ester dalam struktur karboksimetil kitosan. Kekonduksian ion tertinggi yang dicapai adalah 8.44 × 10-4 S cm^-1 dengan kepekatan garam 30 bt. % LiNO₃ pada suhu bilik dan 5.25 × 10^-3 S cm⁻¹ pada suhu 70°C. Filem karboksimetil kitosan-30% LiNO₃ mencapai kestabilan secara elektrokimia sehingga 2.94 V. Keputusan kajian yang diperoleh menunjukkan elektrolit polimer pepejal berasaskan karboksimetil kitosan memberi satu tarikan baru bagi aplikasi bateri ion litium.

Kata kunci: Elektrolit polimer pepejal; FTIR; karboksimetil kitosan; sifat elektrokimia

ABSTRACT

Carboxymethyl chitosan has showed its potential to be used as host polymer for solid polymer electrolyte application. The effect of lithium nitrate towards electrochemical properties of solid polymer electrolyte based carboxymethyl chitosan has been investigated. Solid bio-polymer electrolyte based carboxymethyl chitosan was prepared by solution-casting technique with different ratios of lithium nitrate (LiNO₃) salt. The films were characterized by attenuated total reflected Fourier transform infrared (ATR-FTIR) Spectroscopy and Electrochemical Impedance Spectroscopy to determine the chemical interaction and electrochemical properties of the polymer electrolytes. Based on ATR-FTIR spectra, the lithium ions tend to interact with carbonyl group and ether group in carboxymethyl chitosan structure. The highest conductivity achieved was 8.44 × 10-4 S cm^-1 with a concentration of 30 wt. % of LiNO₃ salt at room temperature and 5.25 × 10-3 S cm⁻¹ at 70°C. The films were electrochemically stable up to 2.94 V. The results suggest that this solid polymer electrolyte based on carboxymethyl chitosan demonstrate potential to be applied in lithium ion batteries.

Keywords: Carboxymethyl chitosan; electrochemical properties; FTIR; solid polymer electrolyte

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*Pengarang untuk surat-menyurat; email: nadhratunnaiim@ukm.edu.my