Y. Mao, X. Sun, Q. Li, Y. Lv
heterostructure, nanomaterials, three-dimensional, nanoforest, microbatteries, energy storage
In micro/nanoelectromechanical systems (MEMS/NEMS) and biomedical devices, the desired on-board power storage and delivery occur in exceptionally small geometric scales, where amount of energy stored on given footprint (J/mm2) precedes that in either unit weight (Wh/kg) or volume (Wh/L). This requirement often poses a distinct challenge on the clumsy two-dimensional battery and supercapacitor configurations that were originally designed for devices thousand or even million times larger in dimension. To address this shortcoming of 2D battery and supercapacitor technology, here, we report the synthesis of 3D ZnO@MnO2 nanowire arrays and nanoforests (i.e. branched nanowire arrays) on titanium substrate to function as electrochemical electrodes. The special nanoforest electrodes enable better electrical conductivity, much larger surface area, and higher electrochemically active material loading than nanowire array counterpart. More specifically, the nanoforests exhibit five times higher capacitance, better rate performance, as well as smaller inner resistance than nanowire arrays. The present work indicates that the reported 3D nanowire and nanoforest electrode possesses a great promise in the application of energy storage devices, especially for powering MEMS/NEMS and other small autonomous devices.