  A natural embodiment for multifunctional materials combining energy-storing
capabilities and structural mechanical properties are layered structures,
similar to both laminate structural composites and electrochemical energy
storage devices. A structural composite with integrated electric double layer
capacitive storage is produced by resin infusion of a lay up including woven
glass fabric used as mechanical reinforcement, carbon nanotube non-woven
fabrics as electrodes/current collectors and a polymer electrolyte. The
energy-storing layer is patterned with holes, which after integration form
resin plugs for mechanical interconnection between layers, similar to rivets.
Finite element modelling is used to optimise rivet shape and areal density on
interlaminar shear properties. Galvanostatic charge discharge tests during
three point bending show no degradation of properties after large deflections
or repeated load/unload cycling at 3.5 V.This mechanical tolerance is a
consequence of the elimination of metallic current collectors and the effective
integration of multifunctional materials, as observed by electron microscopy
and X-ray computed tomography. In contrast, control samples with metallic
current collectors, analogous to embedded devices, rapidly degrade upon
repeated bending.
