Stable layered-layered-spinel structure of the Li1.2Ni0.13Co0.13Mn0.54O2 cathode synthesized by ball-milling assisted solid-state method

Li-rich NMC with a chemical formula of Li1.2Ni0.13Co0.13Mn0.54O2, a type of Li-rich cathode materials built of layered-layered structure, have been gaining interest due to its high specific capacity. However, they suffer from low Coulombic efficiency, poor cycling stability, and poor rate capability. In this work, we have successfully prepared the layered-layered-spinel (LLS) of Li-rich NMC synthesized via a ball-milling assisted solid-state method. The LLS structure can be obtained at a calcination temperature of 950 ℃ for 6 h. Although transformation of some layered structure to spinel has decreased its specific capacity, the obtained LLS structure exhibits better and more stable electrochemical performances than the conventional layered-layered structure. The LLS structure shows an initial Coulombic efficiency of 76%, capacity retention of 86.5% (0.2C for 100 cycles), and improved rate capability at high C-rates, which can be attributed to facile 3D Li-ion diffusion and stabilization effect provided by the spinel structure. The method presented in this work can be adapted as a facile fabrication method to produce the LLS of Li-rich NMC cathodes with good electrochemical performance.