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

Abstract

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.