Abstract: Three-dimensional holey nitrogen-doped carbon matrixes decorated with molybdenum dioxide (MoO₂) nanoparticles have been successfully synthesized via a NaCl-assisted template strategy. The obtained MoO₂/C composites offered multi-advantages, including higher specific surface area, more active sites, more ions/electrons transmission channels, and shorter transmission path due to the synergistic effect of the uniformly distributed MoO₂ nanoparticles and porous carbon structure. Especially, the oxygen vacancies were introduced into the prepared composites and enhanced the Li⁺intercalation/deintercalation process during electrochemical cycling by the Coulomb force. The existence of the local built-in electric field was proved by experimental data, differential charge density distribution, and density of states calculation. The uniquely designed structure and introduced oxygen vacancy defects endowed the MoO₂/C composites with excellent electrochemical properties. In view of the synergistic effect of the uniquely designed morphology and introduced oxygen vacancy defects, the MoO₂/C composites exhibited superior electrochemical performance of a high capacity of 918.2 mAh g^-1 at 0.1 A g^-1 after 130 cycles, 562.1 mAh g^-1 at 1.0 A g^-1 after 1000 cycles, and a capacity of 181.25 mAh g^-1 even at 20.0 A g^-1. This strategy highlights the path to promote the commercial application of MoO₂-based and other transition metal oxide electrodes for energy storage devices.

Key words: MoO₂/C hybrid, 3D holey structure, Oxygen vacancies, Lithium-ion batteries