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 degrees 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. (C) 2013 Elsevier Ltd. All rights reserved.