Complex Impedance Analyses of Li doped ZnO Electrolyte Materials

Shalima Shawuti,Atta Ur Rehman Sherwani,Musa Mutlu Can,Mehmet Ali Gülgün

doi:10.1038/s41598-020-65075-0

Shalima Shawuti, Atta Ur Rehman Sherwani + Show 2 more

Open Access

https://doi.org/10.1038/s41598-020-65075-0

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Journal: Scientific Reports	Publication Date: May 19, 2020
Citations: 24	License type: open-access

Affiliation: Sabancı University, Istanbul University

Abstract

The recent studies indicate that internal point defects in solid electrolytes modify the electronic and ionic conductivity and relaxation mechanism of solid oxide fuel cells. We focused on synthesis of Lithium (Li) doped Zn1-xCoxO (x = 0.00, and 0.10) nanoparticles employing chemical synthesis technique with a reflux setup under constant Argon gas flow. The structural characterizations were performed by x-ray powder diffractometer (XRD) and x-ray photoelectron spectroscopy (XPS). Then, Rietveld refinements were performed to investigate the replacement of Li atom amount in ZnO lattice. Moreover, the variations in ionic conduction dependent on 5, 10 and 20 mol% Li doped ZnO were analysed via ac impedance spectroscopy. The complex measurements were performed in an intermediate temperature range from 100 °C to 400 °C. Ac conductivity responses of each sample were disappeared at a certain temperature due to becoming electronic conductive oxides. However, this specific temperature was tuned to high temperature by Li doping amount in ZnO lattice. Furthermore, the activation energy change by Li dopant amount implied the tuneable ionic conduction mechanism.

Highlights

The recent studies indicate that internal point defects in solid electrolytes modify the electronic and ionic conductivity and relaxation mechanism of solid oxide fuel cells
The last endothermic reaction without mass loss was measured in temperature range of 500 and 1000 °C due to finalize the chemical reactions as Li doped Zinc Oxide (ZnO)
On x-ray powder diffractometer (XRD) patterns, no peak position was observed related to Li atoms or Li compounds which showed that Li atoms were replaced inside of ZnO lattice

Summary

Introduction

The recent studies indicate that internal point defects in solid electrolytes modify the electronic and ionic conductivity and relaxation mechanism of solid oxide fuel cells. Increased in dopant atom amount in oxide semiconductors modified the ionic conductivity, operating temperature, relaxation mechanism and cycle performance in a solid oxide fuel cell[14,15]. For recent technological applications, the most important advantage of Li doped oxide semiconductors are being suitable electrolyte materials for low temperature solid oxide fuel cells[17,18,19,20]. Li doping amount in ZnO created internal point defects of Li substitutions and interstitials Li atoms, which modify the electronic and ionic conductivity and relaxation mechanism by temperature. The studies assigned the nanosize p-n heterojunctions in composite electrolytes create low-temperature operation of solid oxide fuel cells with high ionic conductivity values[11,12,13]. The researchers prove high ionic conductivities of Li+ ions, especially for glassy solid electrolytes[25,26,27]

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Conclusion