Feasibility of Using Li₂MoO₃ in Constructing Li-Rich High Energy Density Cathode Materials

Layer-structured x Li 2 MnO 3 ·(1 – x )Li M O 2 are promising cathode materials for high energy-density Li-ion batteries because they deliver high capacities due to the stabilizing effect of Li 2 MnO 3 . However, the inherent disadvantages of Li 2 MnO 3 make these materials suffer from drawbacks such as fast energy-density decay, poor rate performance and safety hazard. In this paper, we propose to replace Li 2 MnO 3 with Li 2 MoO 3 for constructing novel Li-rich cathode materials and evaluate its feasibility. Comprehensive studies by X-ray diffraction, X-ray absorption spectroscopy, and spherical-aberration-corrected scanning transmission electron microscopy clarify its lithium extraction/insertion mechanism and shows that the Mo 4+ /Mo 6+ redox couple in Li 2 MoO 3 can accomplish the task of charge compensation upon Li removal. Other properties of Li 2 MoO 3 such as the nearly reversible Mo-ion migration to/from the Li vacancies, absence of oxygen evolution, and reversible phase transition during initial (de)lithiation indicate that Li 2 MoO 3 meets the requirements to an ideal replacement of Li 2 MnO 3 in constructing Li 2 MoO 3 -based Li-rich cathode materials with superior performances.