Coordination-assisted fabrication of N-doped carbon nanofibers/ultrasmall Co3O4 nanoparticles for enhanced lithium storage

Abstract

A nanocomposite consists of N-doped carbon nanofibers and Co-containing MOFs (ZIF-67) derived ultrasmall Co3O4 nanoparticles (NCNF/Z-Co3O4 NPs) is prepared via introducing electrospun and coordination-assisted assembly strategies. In this design, Co2+ in the electrospun PAN-Co(Ac)2 nanofibers coordinate with 2-Methylimidazole (2-MeIM) to form ZIF-67 nanocrystals and further convert into ultrasmall Co3O4 NPs dispersed in the carbon fibers matrix. The carbon nanofibers serve as a highly conductive framework interconnect and confine the Co3O4 NPs, thereby improving the electrical conductivity and buffering the volume expansion of Co3O4. In addition, both N-doping originated from ZIF-67 and PAN, as well as the ultrasmall particle size of Co3O4 emerge the surface or near-surface redox reactions, enhancing pseudocapacitive contributions and rendering fast kinetics. Due to these advantages, NCNF/Z-Co3O4 NPs anode shows enhanced lithium storage properties (1189 mAh g−1at 0.1 A g−1, 407 mAh g−1 at 1 A g−1 after 850 cycles and 329 mAh g−1 at 8 A g−1).