Study the structure and electrochemical performance of BaTiO3/S electrode for magnesium-ion batteries
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)
- et al.
J. Power Sources
(2009) - et al.
Nano Energy
(2017) - et al.
J. Power Sources
(2019) - et al.
Nano Energy
(2017)