Ionic liquid-derivatized hierarchical N-doped carbon-coated Co₃O₄ nanosheet array as high-performance anode materials for lithium-ion batteries

A novel nitrogen-doped carbon-coated graded Co₃O₄ nanosheets (NDC/Co₃O₄ NS) is synthesized by using a simple ionic liquid hydrothermal method. The as-prepared NDC/Co₃O₄ NS is composed of hexagonal nanosheets having different orientation and the thickness of 50–100 nm. Significantly, as an anode electrode for lithium-ion batteries (LIBs), the NDC/Co₃O₄ NS performed excellent cyclability. The NDC/Co₃O₄ NS delivers an initial discharge capacity of 1281.4 mAh g⁻¹ at 445 mA g⁻¹ and maintains a reversible high capacity of 929.4 mAh g⁻¹ after 50 cycles, much higher than the unmodified Co₃O₄ nanosheets (230 mAh g⁻¹). The superior excellent electrochemical performance can be attributed to the gradient structure and the nitrogen-doped carbon coating resulting in shorter ion transport distances and good electrical conductivity.