Elsevier

Materials Letters

Volume 284, Part 2, 1 February 2021, 129033
Materials Letters

Study the structure and electrochemical performance of BaTiO3/S electrode for magnesium-ion batteries

https://doi.org/10.1016/j.matlet.2020.129033Get rights and content

Highlights

  • The BaTiO3/S nanocomposite is synthesized by a sonochemical method.

  • The BaTiO3/S nanocomposite exhibits 270 mA h g−1 at 55 °C.

  • APC electrolyte decomposes at the surface of the cathode result irreversible electrolyte/electrode interface.

  • DMg2+ ~ 10−22 cm2 s−1 confirms high Mg diffusion energy barrier in the framework of BTO and BTO/S.

Abstract

This paper is an attempt to design new cathodic materials for rechargeable magnesium batteries (RMBs) via combining sulfur (S) with BaTiO3 (BTO) by a sono-chemical method. X-ray diffraction (XRD) demonstrates that the introduction of sulfur within the framework of a tetragonal BTO results a small shift of the (1 0 1) plane of BTO from 31.44° to 31.61°. The electrochemical performance of the composite is analyzed by cyclic voltammetry (CV), electrochemical impedance spectroscopy and battery testing system. CV curves of BaTiO3 and BTO_S composite electrodes show capacitive behavior correspond to reactions at the cathode surface with magnesium ions. BaTiO3 and BTO_S composite electrodes display low diffusion coefficient of Mg2+ ~10−22 cm2 s−1. Mg/BTO and Mg/(BTO_S) button cells deliver initial discharge capacity of 1.6/1.4 mAh g−1, at room temperature and 315/270 mA h g−1 at 55 °C, respectively.

Introduction

The searching for high-performance cathode material remains the most critical hurdle toward realizing practical Mg full cell. BaTiO3 has a tetragonal phase at room temperature and the reason of its spontaneous polarization is that the Ti atom deviates from the center of the oxygen octahedron causing displacement along the direction of the fourfold axis [1]. Sulfur (S) has an extremely high theoretical capacity at 1675 mAh g−1, low cost, and abundant in the Earth's crust. Sulfur based cathodes suffer from low potential in compared to (Mg/Mg2+), dissolution of intermediate reaction products (polysulfides) in electrolyte, and volume change ~80% [2]. The ferroelectric nature of BTO enables a self-polarized electric field upon the battery operation where the negatively charged polysulfide anions can be anchored via the electrostatic force [3], [4]. Herein, we study the effect of S on the physicochemical performance of the BaTiO3 electrode. Electrochemical kinetic and the nature of the charge storage of BTO and BTO_S were analyzed by the electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV).

Section snippets

Experimental

BTO_S composite was synthesized with a sonochemical method. BaTiO3 was mixed with sulfur in a molar ratio of 70:30, and the composite was dispersed in 100 cm3 of deionized water and two drops of diethanolamide. The mixture was sonicated for 3 h and heated at 80 °C for 24 h. Morphology and microstructure were characterized by field emission scanning electron microscopy (Quanta 250 FEG). Elemental mapping was measured using an energy dispersive spectrometer (INCA Energy, Oxford Instruments).

Results and discussion

Fig. 1 (a) and (b) present the SEM image of BTO and BTO_S composite. Pure BTO image shows random and spherical type of nanoparticles with relatively dense microstructure. By adding sulfur, (Fig. 1(b)), the image shows a significant homogenous distribution all over the surface. Fig. 1(c) displays the EDS spectrum of BTO_S composite and the corresponding data are illustrated inset. The spectrum shows characteristic bands indexed to Ba, Ti, O, and S elements and reveals that the composition ratio

Conclusion

BTO_S composite was prepared via sonochemical method and their electrochemical properties are compared with BTO. The crystallite size of BTO increased due to introduction of sulfur and the lattice constant of BTO decreased from 2.84 to 2.83 Å. This change emphasize that the sulfur is being successfully perturbed by the crystal structure of BTO, although the fundamental understanding of the trapping mechanism of sulfur via the spontaneous polarization of ferroelectric materials is unclear. The

CRediT authorship contribution statement

E. Sheha: Conceptualization, Methodology, Validation, Data curation. E.M. Kamar: Methodology, Validation, Data curation. Li-Zhen Fan: Validation, Conceptualization.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

This study was funded by Chinese-Egyptian Research Fund (CERF) (grant number 2017YFE0113500 (China) & 30340 (Egypt)).

References (9)

  • X. He et al.

    J. Power Sources

    (2009)
  • Z. Hao et al.

    Nano Energy

    (2017)
  • Z. Zhao et al.

    J. Power Sources

    (2019)
  • X. Miao et al.

    Nano Energy

    (2017)
There are more references available in the full text version of this article.

Cited by (0)

View full text