Zeolitic imidazolate frameworks derived Co nanoparticles anchored on graphene as superior anode material for lithium ion batteries

Cobalt nanoparticles anchored on graphene composites (Co/G composites) have been successfully synthesized by pyrolyzing the zeolitic imidazolate frameworks (ZIF-67)/graphene oxide composites. The structural characterization reveals that ZIF-67 derived Co nanoparticles with diameter of less than 100 nm are homogeneously distributed on the graphene sheets. When employed as anode for lithium ion batteries (LIBs), the composites deliver an initial discharge capacity of 670.8 mAh g−1 at a low current density of 50 mA g−1, and after 120 cycles, the capacity can be maintained at 562.4 mAh g−1. The composites can also display long cycling stability when measured at alternating high current. Even at 2000 mA g−1, a reversible discharge capacity of 248.8 mAh g−1 can be achieved after 1000 long cycles. The synergistic effect of Co nanoparticles and the excellent conductivity of the graphene matrix contribute to the superior cycle performance and rate capability of the composite electrodes.