Enhanced AC conductivity and dielectric properties of ultrathin β-silver vanadium oxide/aniline nanowires
Introduction
There has been renewed interest in one dimensional (1-D) nanostructures such as nanowires, nanoribbons, nanobelts, and nanotubes because of their excellent properties as compared to bulk materials [1], [2]. To be more specific, these nanostructures are critical for applications such as lithium ion batteries, optoelectronic sensors, and drug delivery systems because of their large surface areas, low density and enhanced surface permeability [3], [4]. Selected metal oxides such as LiFePO4 and V2O5 are being used for lithium ion battery cathodes. Over the last few years, silver vanadium oxides (SVOs) have drawn significant attention owing to their long-term stability and high energy density, making them good candidates as active cathode materials for lithium ion batteries [5], [6], [7], [8], [9], [10], [11], [12]. The reduction of silver ions has been reported to form silver nanoparticles and nanowires within the cathode, which contributes to a significant increase in cell conductivity upon discharge [13], [14]. Polyaniline (PANI) is considered among the few well-suited candidates for this application because of its excellent environmental stability and high electrical conductivity [15], [16]. SVOs have been widely used as a cathode material in batteries that power ICDs because of their high electrical conductivity [10], [17], [18], [19], [20], [21], [22]. However, they failed to do in-depth studies on the impedance of SVO. We studied AC conductivity and dielectric properties at room temperature in the frequency range between 100 Hz and 5 MHz.
Section snippets
Synthesis
All chemicals were commercially available and used as received. β-SVO nanowires were synthesized by using an advanced hydrothermal approach, AgNO3 and NH4VO3 are reacted at 180 °C for 24 h. The as prepared β-SVO were dispersed in deionized water under uniform magnetic stirring. Aniline (20 wt%–70 wt%) was added under continuous stirring. After 12 h, ammonium persulfate in a 1:1 M ratio with the monomer was added to the solution. The resulting products were then filtered and washed with ethanol
Results and discussion
A large quantity of β-SVO nanowires with lengths of several tens of micrometers are shown in Fig. 2(a). It should be noted that the morphology and the crystal structure of the obtained β-SVO nanowire/aniline nanocomposites was changed as the aniline was adsorbed onto the surface of β-SVO nanowires during the reaction, as shown in Fig. 2(b)–(f). We found that the diameter of the synthesized nanowires was approximately 50 nm, whereas that of the nanocomposites was approximately 82 nm, 100 nm, and
Conclusion
A noticeable increase in AC conductivity was observed from 8.07 × 10−5 S m−1 to 8.57 × 10−5 S m−1 with 50 wt% loading of aniline. This work demonstrates that the synthetic route proposed herein is an effective and facile technique for producing ultrathin nanostructures and for improving their dielectric properties and AC conductivity for applications as a high performance power electronics.
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