An Li-rich oxide cathode material with mosaic spinel grain and a surface coating for high performance Li-ion batteries

Lithium-rich layered oxides are considered to be one of the most promising cathode materials for lithium ion batteries due to their extremely high reversible capacity. Here, we report the design of a novel heterostructured Li1.2Ni0.13Co0.13Mn0.54O2 material with mosaic spinel nanograins and a surface coating, which is synthesized by a facile and green one-step solid-phase surface-modification process. We propose that the chemical Li leaching from Li2MnO3 simultaneously induces the formation of a fluorite coating and the layer-to-spinel phase transformation at high temperatures. The fluorite coating protects the lithium-rich oxides from direct exposure to the highly active electrolyte. The spinel phase provides an efficient path for Li+ mobility and also facilitates the suppression of the initial irreversible capacity loss. This unique heterostructured Li1.2Ni0.13Co0.13Mn0.54O2 material thus exhibits an outstanding initial Coulombic efficiency, superior rate capability and excellent cyclability. The design concept and facile synthetic strategy can be applied to both advanced lithium ion batteries and other high-performance energy storage devices.