Net-structured Co3O4/C nanosheet array with enhanced electrochemical performance toward lithium storage

• Co3O4/C nanosheet array on nickel foam was synthesized by hydrothermal method, followed by magnetron sputtering of a carbon layer.
• The Co3O4/C nanosheet array electrode delivers an initial discharge capacity of 1340.4 mAh g−1 at 0.1 C.
• After 100 cycles, the capacity retention of the Co3O4/C is 88.8% of its initial discharge capacity.
• The enhanced electrochemical performances are attributed to the porous nanosheet array and the thin carbon layer coated on Co3O4 nanosheets.

Freestanding Co3O4/C nanosheet array growing directly on nickel foam substrate was synthesized using a hydrothermal approach, followed by a direct current magnetron sputtering of a thin carbon layer. The Co3O4 nanosheets with thicknesses of 10–20 nm are interconnected with each other, forming a highly open net-structure. The Co3O4/C nanosheet array electrode delivers an initial discharge capacity of 1340.4 mAh g−1 at 0.1 C, and maintains a high specific capacity of 912.1 mAh g−1 at room temperature and can still remain 88.8% of its initial discharge capacity at 55 °C at 1 C after 100 cycles. The enhanced electrochemical performances are attributed to the porous nanosheet array and the thin carbon layer coated on Co3O4 nanosheets, which cannot only facilitate Li+ and electron transportation in the electrode, but also improve its structure stability during cycling.

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