Nitrogen-doped porous carbon spheres anchored with Co3O4 nanoparticles as high-performance anode materials for lithium-ion batteries

• The Co3O4/nitrogen-doped porous carbon spheres (NPCS) nanocomposites as an anode material for lithium-ion batteries (LIBs) were synthesized by a facile hydrothermal method.
• The charge/discharge test showed a high initial lithiation specific capacity of 1245.5 mAh g−1, which was maintained at 983.9 mAh g−1 even after 100 cycles.
• The lithiation specific capacity was retained 659 mAh g−1 at a high current density of 5 A g−1, which is about 1.8 times of the theoretical capacity of graphite.
• The synergetic effects of the nanoscale Co3O4 particles, the porous structure of the NPCS and the N functional groups on the NPCS are responsible for the excellent electrochemical performance of the Co3O4/NPCS nanocomposites.
• The excellent performances of the Co3O4/NPCS nanocomposites make them potential anode materials for LIBs.

In this work, Co3O4 nanoparticles were loaded on the nitrogen-doped porous carbon spheres (NPCS) by a facile hydrothermal method. The NPCS were derived from carboxymethyl chitosan as the carbon and nitrogen source. The as-prepared Co3O4/NPCS nanocomposites were used as anode materials for lithium-ion batteries. The electrochemical results showed that the materials possessed a high initial discharge capacity of 1245.5 mAh g−1 and still maintained a high reversible capacity of 983.9 mAh g−1 after 100 cycles at a current density of 100 mA g−1. Even at a high current density of 5 A g−1, it delivered a very stable reversible capacity of 659 mAh g−1. The high electrochemical performance of the Co3O4/NPCS nanocomposites can be attributed to the synergistic effects of the nanoscale Co3O4 particles, the porous structure of the NPCS and the N functional groups on the NPCS.