Vertically aligned iron oxide nanotube arrays and porous magnetite nanostructures as three-dimensional electrodes for lithium ion microbatteries

The simple preparations of vertically aligned iron oxide nanotube arrays and porous magnetite nanostructures and their application as three-dimensional electrodes for lithium ion microbatteries are introduced. Nanotube arrays are well formed across a very large area with a ∼40 nm nanotube diameter. The nanotubes change to be porous nanostructures like nano-pillar arrays after heat treatment under 10% H₂. These two structures allow the omission of conductive agents and binder in the battery assembly. In addition, the structural advantages for lithium ion and electron transport are exhibited through excellent cyclic stability and rate capability even at very high current density, which can complete one charge/discharge in a few minutes.