Carbon-based polymer nanocomposites as dielectric energy storage materials

Nanostructured polymeric materials based on conductive nanofillers have promising applications in the energy storage field owing to the extraordinary characteristics of the nanofillers. Conductive nanofillers, such as graphene nanoplatelets, are characterized by small size, extraordinary surface area to volume ratio, high aspect-ratio and extremely low electrical resistivity. In this work, the dielectric behaviors and the corresponding energy storage capabilities of high aspect-ratio carbon nanofiller/polymer composites were reviewed. At the electrical percolation point, a conductive composite exhibits a sudden and remarkable enhancement in dielectric constant and dielectric loss. The challenge is to maintain the increase in dielectric constant while preventing the increase in dielectric loss. Various physical and chemical methodologies have been followed to overcome this challenge including surface chemistry modifications, physical alignment of nanofillers and utilizing of hybrid mixtures. Promising results were reported to minimize the energy loss due to the conductive network formation. Nanocomposites with a dielectric constant of 10³ and dielectric loss of only 0.08 were successfully fabricated. However, more work is still needed for a further enhancement in dielectric constant and reduction in the energy loss and to improve the storage capabilities of the nanocomposites.