The effective ionic conductivity in a composite structure is believed to
decrease rapidly with volume fraction. A system, such as a bipolar device
or energy storage device, has structures or components in which the
diffusion length or path that electrodes or ions must traverse is
minimized and the interfacial area exposed to the ions or electrons is
maximized. The device includes components that can be reticulated or has
a reticulated interface so that an interface area can be increased. The
increased interfacial perimeter increases the available sites for
reaction of ionic species. Many different reticulation patterns can be
used. The aspect ratio of the reticulated features can be varied. Such
bipolar devices can be fabricated by a variety of methods or procedures.
A bipolar device having structures of reticulated interface can be
tailored for the purposes of controlling and optimizing charge and
discharge kinetics. A bipolar device having graded porosity structures
can have improved transport properties because the diffusion controlling
reaction kinetics can be modified. Graded porosity electrodes can be
linearly or nonlinearly graded. A bipolar device having perforated
structures also provides improved transport properties by removing
tortuosity and reducing diffusion distance.