Influence of Ion Transport Parameters on Conductivity at Room Temperature in DMSO-TPAI-I2 Electrolyte
1Centre of Foundation Studies for Agricultural Science, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
2Ionic Materials and Energy Devices Laboratory, Physics Department, Faculty of Science, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
*Email Address : imnoor@upm.edu.my
Abstract : Understanding the factors that influence the conductivity variations in electrolyte system is essential. In this work, the transport parameter namely the charge carrier concentration (n), the charge carrier mobility (μ), and the charge carrier diffusivity (D) have been evaluated. A liquid electrolyte system consisting different concentrations of tetrapropylammonium iodide (TPAI) and iodine (I2) in dimethyl sulfoxide (DMSO) have been prepared. Variations of room temperature conductivity at different salt content has been plotted. Conductivity was observed to increase from (5.21±0.27) mS cm-1 (L1 electrolyte) to (8.01±0.09) mS cm-1 (L3 electrolyte). The increased in conductivity was attributed to the increased in n due to the dissociation of more free ions. The charge carrier mobility (μ) and diffusivity (D) decreased from (7.91±0.30)×10-5 cm2 V-1 s-1 and (2.03±0.08)×10-6 cm2 s-1 to (5.28±0.08)×10-5 cm2 V-1 s-1 and (1.36±0.02)×10-6 cm2 s-1, respectively. The decreased in μ and D were attributed to the increased in ion collisions in the electrolyte. The addition of more TPAI salt into the L3 electrolyte reduced the conductivity of the electrolyte which can be attributed to the decreased in n due to the increased in ion association. The μ and D increased as more TPAI salt is added into the L3 electrolyte which associated to the increased in ion flow due to less ion collisions. Based on this work, the conductivity variation of DMSO-TPAI-I2 electrolyte at room temperature is strongly controlled by n, not μ.
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