Ultrafine molybdenum oxycarbide nanoparticles embedded in N-doped carbon as a superior anode material for lithium-ion batteries

Abstract

A facile and scalable strategy was developed for in situ preparation of ultrafine molybdenum oxycarbide (MoOC) nanoparticles embedded in a porous N-doped carbon matrix by pyrolysis of molybdenum–imidazole frameworks in an argon atmosphere. The composite contains a high content (∼83 wt%) of electrochemical active material MoOC. When evaluated as an anode material for lithium-ion batteries, the as-obtained porous MoOC/N-doped C composite electrode exhibits high reversible lithium specific capacity (1217 mA h g−1 at 50 mA g−1), excellent rate capability (481 mA h g−1 at 1 A g−1), and good cycle stability (361 mA h g−1 at 2 A g−1 for 100 cycles). The superior lithium storage capability was ascribed to the unique structure with ultrafine and high-containing MoOC nanocrystals embedded in a porous N-doped carbon matrix. The porous N-doped carbon matrix can largely enhance the electronic conductivity of the composite, remarkably increasing rate capability. Meanwhile, the carbon matrix can effectively accommodate the volume change and reduce the aggregation of the MoOC nanoparticles during charge/discharge process, significantly enhancing cycle stability of the composite electrode. The superior electrochemical performance indicated that the attained porous MoOC/N-doped C composite could be a promising anode material for next generation high-performance lithium-ion batteries.