3D Foam-Like Composites of Mo₂C Nanorods Coated by N-Doped Carbon: A Novel Self-Standing and Binder-Free O₂ Electrode for Li–O₂ Batteries

The development of self-standing and binder-free O 2 electrodes is significant for enhancing the total specific energy density and suppressing parasitic reactions for Li–O 2 batteries, which is still a formidable challenge thus far. Here, a three-dimensional foam-like composite composed of Mo 2 C nanorods decorated by different amounts of N-doped carbon (Mo 2 C-NR@ x NC ( x = 5, 11, and 16 wt %)) was directly employed as the O 2 electrode without applications of any binders and current collectors. Mo 2 C-NR@ x NC presents a network microstructure with interconnected macropore and mesoporous channels, which is beneficial to achieving fast Li + migration and O 2 diffusion, facilitating the electrolyte impregnation, and providing enough space for Li 2 O 2 storage. Additionally, the coated N-doped carbon layer can largely improve the electrochemical stability and conductivity of Mo 2 C. The cell with Mo 2 C-NR@11NC shows a considerable cyclability of 200 cycles with an overpotential of 0.28 V in the first cycle at a constant current density of 100 mA g –1, a superior reversibility associated with the formation and decomposition of Li 2 O 2 as desired, and a high electrochemical stability. On the basis of the experimental results, the electrochemical mechanism for the cell using Mo 2 C-NR@11NC is proposed. These results represent a promising process in the development of a self-standing and binder-free foam-based electrode for Li–O 2 batteries.