Three-dimensional core@shell nano-array electrodes for integrated Lithium-ion microbatteries

To overcome the distinct challenge posed on the clumsy two-dimensional configuration that was originally designed and currently widely employed for electrochemical energy storage devices with large lateral dimension, here we designed and synthesized two types of electrochemical electrodes with three-dimensional (3D) configurations on titanium substrate. Structural characterization and electrochemical measurements on electrodes composed of the ZnO@MnO₂ core@shell nanowire arrays or nanoforests (i.e. branched nanowire arrays) demonstrated that the electrodes with novel nanoforest architecture possess better electrical conductivity, larger surface area, and higher electrochemically active material loading than their nanowire array counterparts. More specifically, the nanoforest electrodes exhibit five times higher areal capacitance, better rate performance, as well as smaller inner resistance than nanowire array electrodes. These novel 3D architectures offer promising designs for powering microelectronics and other small autonomous devices with exceptionally small geometric scales.