Magnesium titanate as high-performance cathode material for magnesium-ion batteries

Abstract

Magnesium-ion battery (MIB) is evolving as a promising substitute to lithium-ion battery (LIB), presenting higher energy density, essential safety, longer cycle life, material's abundance, and cost-effectiveness. This study is dedicated to investigate the electrochemical performance of magnesium titanate oxide for application as cathode material in MIBs. The mechanism of demagnesiation process, representing the coupled release of Mg2⁺ and electrons, is systematically investigated. While, the Ti–O framework upheld its structural strength during progressive demagnesiation, the extraction process became gradually unfavorable at higher x in Mg₅ − x Ti₁₃O₃₀. The proposed cathode offered specific capacity of 227 mAh/g with electrochemical potential of 3.92 V to exhibit energy density of 885 Wh/kg coupled with feasible voltage profile during magnesiation. The external electric field caused reduction in Mg–O bond length exhibiting improved magnesiation in favor of efficient charging. The migration of Mg in the cathode indicates favorable pathway on the basis of low diffusion barrier of 0.23 eV and a high diffusion coefficient of 1.37 × 10⁻⁹ cm2/s, exhibiting efficient Mg2⁺ transport. At the surface of the cathode, the oxidation of the electrolyte C₆H₁₄O₃ lead to the formation of cathode–electrolyte interphase layer consisting of species like Mg–O–CH₃, Ti–O–CH₃, and MgCO₃ which provides a shielding but ionically permeable interface per requirements of the MIB. The study demonstrates the suitability of Mg₅Ti13O₃₀ as cathode for MIBs on the basis of stability, electronic characteristics, high storage capacity, operating voltage, and facile diffusion mechanism when compared with contemporary materials.

Keywords Magnesium, Migration, Magnesium-ion battery , cathode–electrolyte.