Beta-manganese dioxide nanoflowers self-assembled by ultrathin nanoplates with enhanced supercapacitive performance

Hierarchical porous beta-MnO2 nanoflowers self-assembled by ultrathin (thickness less than 10 nm) nanoplates have been successfully fabricated at room temperature. Because of its high specific surface area (267 m(2) g(-1)) and proper pore size distributions (average pore size, ca. 5.9 nm), the obtained 3D nanomaterials achieve enhanced capacitance as high as 296.3 F g(-1) at a scanning rate of 2 mV s(-1), which is similar to 20 times of those of the traditionally prepared nanostructural beta-MnO2 (e. g. 1D hollow beta-MnO2 nanorods with similar to 14.9 F g(-1)). Furthermore, it has an appreciable ability to deliver large energy densities at high rates (67.4% capacitive retention). The comparable property with alpha-MnO2 indicates that such low-cost porous beta-MnO2 nanoflowers may also be a very promising candidate material for supercapacitors besides lithium battery material.