In-situ reduction derived nitrogen doped carbon anchored cobalt nanoparticles as highly capacity and long life lithium ion battery anodes

A novel composite with embedded cobalt nanoparticles in nitrogen doped carbon (Co@NDC) is synthesized by the in-situ reduction of Co(OH)(2) using ionic liquid [HMIm]N(CN)(2) as carbon precursor. Due to the special structure, this composite can form more stable solid electrolyte interface (SEI) film than cobalt nanoparticles when used as anode. The Co@NDC electrode shows a high discharge capacity of 1322mAhg(-1) after 850 cycles at 0.5C, and an extremely long cycle life (436mAhg(-1) after 2400 cycles at 5C). This excellent electrochemical performance can be attributed to the catalytic lithium-carbon reaction of cobalt nanoparticles, high conductivity of the carbon material, and the thin and stable SEI film.