MLi2Ti6O14 (M = Sr, Ba, and Pb): new cathode materials for magnesium–lithium hybrid batteries

Abstract

Magnesium–lithium hybrid batteries (MLHBs) are playing an increasingly important role in energy storage systems owing to their abundant raw materials and favorable safety characteristics. Consequently, MLi₂Ti₆O₁₄ (M = Sr, Ba, and Pb) compounds have been synthesized via a sol–gel method, followed by calcination. For the first time, as cathodes for MLHBs, MLi₂Ti₆O₁₄ (M = Sr, Ba, and Pb) showed good electrochemical properties. For example, at 50 mA g⁻¹, the specific capacities of MLi₂Ti₆O₁₄ (M = Sr, Ba, and Pb) after 300 cycles are 75.6, 68.2 and 76.3 mA h g⁻¹, respectively. In addition, MLi₂Ti₆O₁₄ (M = Sr, Ba, and Pb) also possess outstanding rate performances. Importantly, the ion storage mechanism of MLi₂Ti₆O₁₄ (M = Sr, Ba, and Pb) compounds in MLHBs was studied with PbLi₂Ti₆O₁₄ as the representative. These results reveal that MLi₂Ti₆O₁₄ (M = Sr, Ba, and Pb) have good electrochemical reversibility, and can be used as cathodes for MLHBs.