Mechanochemical synthesis of Li₂MnO₃ Shell/LiMO ₂ (M = Ni, Co, Mn) core-structured nanocomposites for lithium-ion batteries

Core/shell-like nanostructured xLi₂MnO₃·(1 - x)LiMO₂ (M = Ni, Co, Mn) composite cathode materials are successfully synthesized through a simple solid-state reaction using a mechanochemical ball-milling process. The LiMO₂ core is designed to have a high-content of Ni, which increases the specific capacity. The detrimental surface effects arising from the high Ni-content are countered by the Li ₂MnO₃ shell, which stabilizes the nanoparticles. The electrochemical performances and thermal stabilities of the synthesized nanocomposites are compared with those of bare LiMO₂. In particular, the results of time-resolved X-ray diffraction (TR-XRD) analyses of xLi ₂MnO₃·(1 - x)LiMO₂ nanocomposites as well as their differential scanning calorimetry (DSC) profiles demonstrate that the Li₂MnO₃ shell is effective in stabilizing the LiMO₂ core at high temperatures, making the nanocomposites highly suitable from a safety viewpoint.