Reversible Three-Electron Redox Reaction of Mo³⁺/Mo⁶⁺ for Rechargeable Lithium Batteries

To increase the energy density of lithium batteries, the development of high-capacity positive electrode materials is essential. Herein, we propose the use of a three-electron redox reaction of Mo³⁺/Mo⁶⁺ for a new series of high-capacity lithium insertion materials. In this study, a binary system of LiMoO₂-Li₃NbO₄ is targeted, and nanosize and metastable Li_9/7Nb_2/7Mo_3/7O₂ is successfully prepared by a mechanical milling process. The sample delivers a large reversible capacity of ∼280 mAh g^-1 in a Li cell with good capacity retention. On the basis of these results, the future possibility of high-capacity electrode materials with a three-electron Mo³⁺/Mo⁶⁺ redox reaction is discussed.