For the first time, we successfully synthesize a self-supported Na0.7CoO2 nanosheet arrays via the facile "sodiation and post-calcination" method. Different from the traditional high temperature solid-state technique, this facile strategy can easily maintain the novel construction of the precursor. A mass loading as high as 8 mg cm(-2) is achieved for the Na0.7CoO2 electrode with an initial capacity of 145.2 mAhg(-1) at 1 C. Most importantly, the corresponding areal capacity for the Nao.7CoO2 electrode is calculated to be 1.16mAhcm(-2). This superb areal capacity is higher than that of the previously reported cathode materials. This special "sodiation and postcalcination" protocol mentioned in this article guarantees the high mass loading of Nao.7CoO2 on Ni foam, providing a straightforward direction for engineering high-areal-capacity cathode materials.