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 1322 mAh g⁻¹ after 850 cycles at 0.5 C, and an extremely long cycle life (436 mAh g⁻¹ after 2400 cycles at 5 C). 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.