[1] The space inside the holes is so small that billions of pores combined equal the volume of a grain of sand.
It held two vanadium pentoxide nanotube electrodes separated by an electrolyte that carried the electrical charge between the two.
The battery asymmetrically cycles between 0.2 V and 1.8 V.[3] The capacity retention of this full cell (relative to 1 C values) is 95% at 5 C and 46% at 150 C, with a 1,000-cycle life.
[1] The system uses an electrochemical regime in which ion insertion and surface charge mechanisms for energy storage become indistinguishable.
It can serve as a vehicle for studying ion transport limits in dense, nanostructured, electrode arrays.