Abstract
Nanofiller-doped polymer electrolyte-based electrochemical devices are now emerged as a novel material for electrochemical devices. This paper reports a solid polymer electrolyte film doped with a new nanofiller synthesized by the solution casting technique. Electrical, Optical, and photoelectrochemical characterization are presented in detail. Electrochemical impedance spectroscopy (EIS) shows with the dispersion of nanofillers conductivity increases attains maxima and decreases. The maximum conductivity was at 0.05 wt% nanofiller concentration of 3.25 x 10-5 S/cm. The calculated ionic transference value was 0.92 which shows the domency of the system as ionic. The linear sweep voltammetry confirms a high electrochemical stability window (ESW) of 4.01V. Sandwitched electrical double-layer capacitors (EDLC) has been developed using carbon-based electrodes and sandwitched nanofiller dispersed polymer electrolyte, showing a high specific capacitance value of ~ 200 F/g.
Keywords— Polymer electrolyte, Conductivity, Nanocomposite polymer electrolyte, Supercapacitors
Introduction:
Nanofiller as dispersoid in polymer electrolytes is a known established system playing a dominant role in day-to-day devices[1–3]. Nanofiller with polymer electrolyte matrix plays a dual role in the sense one side enhances electrical conductivity (σ) by establishing a quantum size effect, other side enhances mechanical stability of an atom[4–7]. The ionic conducting polymers, known as Solid polymer electrolytes [SPE] , that has been extensively researched and produced since the 1970s. Wright first described ionic conductivity in polyethylene oxide (PEO)/salt compounds in 1973[8]. In 1979, Armand claimed that at temperatures between 303K and 353K, the electrical conductivity of PEO/salt complexes might reach 10-5 S cm-1. [9]. Polymer electrolytes have been developed primarily for Li+ and Na+ions, two of the most common and abundant alkali metal ions.
In this study, we focus on the polymer-salt electrolyte combination PEO: NaI in which the conductivity results from the conduction of Na+ ions. PEO compounds with NaPF6 [10], NaSCN, NaI, and NaCF3SO3 were the subject of earlier work on Na+ ion conducting polymeric electrolytes [11]. Additionally, the sodium batteries that use these electrolytes are rechargeable solid-state devices [12], [13]. A polymer electrolyte of poly (ethylene oxide) and sodium iodide (PEO-NaI) has been demonstrated to conduct Na+ ions and to some extent anionic conduction. To enhanced the conductivity of PEO-based electrolytes at lower operating temperatures, researchers proposed multiple techniques to incorporate nano-scale an inorganic fillers, that includes SiO2 [14], Al2O3[15], TiO2 [16], ZnO [17], ZrO [18], CeO2 [19], and CuO [20], without involveing the other physical properties, such as electrolyte reactivity towards electrode, mechanical stability, etc [21,22].
In MXene multilayer nanoflake doped polymer electrolyte, we have tried to develop a new nanofiller i.e. Ti3C2Tx MXene doped polymer electrolyte system. Polymer electrolyte chosen as host PEO:NaI in which maxima in ionic conductivity was reported at 12 wt % sodium iodide (NaI) concentration 1.05 x 10-7 S/cm. We have dispersed MXene at various wt%. (i.e., 0.01% to 0.07%). These multilayer nanoflake polymer electrolytes were systematically characterized by various characterization tools and their results are summarized in present paper.
Experimental Details:
Material and Method :
The polymer PEO with an average molecular weight of 100,000 was purchased from ADRICH Chemistry Pvt. Ltd. in USA, while NaI (extra pure) with a molecular weight of 166.01 g/mol was purchased from FINAR Reagents Pvt., India. Ti3C2Tx MXene multilayer nanoflake having molecular weight of 167.62g/mol was purchased from Nanoshel UK Limited with purity of 99.9%. Before use, the multilayer nanoflake and other solvents utilized in this investigation were thoroughly dried.