On the Beneficial Effect of MgCl₂ as Electrolyte Additive to Improve the Electrochemical Performance of Li₄Ti₅O12 as Cathode in Mg Batteries

Marta Cabello; Gregorio F Ortiz; Pedro Lavela; José L Tirado

doi:10.3390/nano9030484

On the Beneficial Effect of MgCl₂ as Electrolyte Additive to Improve the Electrochemical Performance of Li₄Ti₅O₁₂ as Cathode in Mg Batteries

Nanomaterials (Basel). 2019 Mar 26;9(3):484. doi: 10.3390/nano9030484.

Authors

Marta Cabello¹, Gregorio F Ortiz², Pedro Lavela³, José L Tirado⁴

Affiliations

¹ Departamento de Química Inorgánica e Ingeniería Química, Instituto Universitario de Investigación en Química Fina y Nanoquímica (IUNAN), Universidad de Córdoba, Campus de Rabanales, Edificio Marie Curie, E-14071 Córdoba, Spain. z22cabbm@uco.es.
² Departamento de Química Inorgánica e Ingeniería Química, Instituto Universitario de Investigación en Química Fina y Nanoquímica (IUNAN), Universidad de Córdoba, Campus de Rabanales, Edificio Marie Curie, E-14071 Córdoba, Spain. q72maorg@uco.es.
³ Departamento de Química Inorgánica e Ingeniería Química, Instituto Universitario de Investigación en Química Fina y Nanoquímica (IUNAN), Universidad de Córdoba, Campus de Rabanales, Edificio Marie Curie, E-14071 Córdoba, Spain. iq1lacap@uco.es.
⁴ Departamento de Química Inorgánica e Ingeniería Química, Instituto Universitario de Investigación en Química Fina y Nanoquímica (IUNAN), Universidad de Córdoba, Campus de Rabanales, Edificio Marie Curie, E-14071 Córdoba, Spain. iq1ticoj@uco.es.

Abstract

Magnesium batteries are a promising technology for a new generation of energy storage for portable devices. Attention should be paid to electrolyte and electrode material development in order to develop rechargeable Mg batteries. In this study, we report the use of the spinel lithium titanate or Li₄Ti₅O₁₂ (LTO) as an active electrode for Mg²⁺-ion batteries. The theoretical capacity of LTO is 175 mA h g^-1, which is equivalent to an insertion reaction with 1.5 Mg²⁺ ions. The ability to enhance the specific capacity of LTO is of practical importance. We have observed that it is possible to increase the capacity up to 290 mA h g^-1 in first discharge, which corresponds to the reaction with 2.5 Mg²⁺ ions. The addition of MgCl₂·6H₂O to the electrolyte solutions significantly improves their electrochemical performance and enables reversible Mg deposition. Ex-situ X-ray diffraction (XRD) patterns reveal little structural changes, while X-ray photoelectron spectrometer (XPS) (XPS) measurements suggest Mg reacts with LTO. The Ti³⁺/Ti⁴⁺ ratio increases with the amount of inserted magnesium. The impedance spectra show the presence of a semicircle at medium-low frequencies, ascribable to Mg²⁺ ion diffusion between the surface film and LTO. Further experimental improvements with exhaustive control of electrodes and electrolytes are necessary to develop the Mg battery with practical application.

Keywords: Li4Ti5O12; MgCl2; cathodes; magnesium batteries.

Abstract

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