Enhanced dielectric properties and breakdown strength of polymer/carbon nanotube composites by coating an SrTiO3 layer

In this work, strontium titanate (STO) was coated on the surface of carbon nanotubes (MWCNTs) through a sol–gel method to form a core–shell structure hybrid powder (STO@MWCNTs). This powder was then added to polydimethylsiloxane to prepare a flexible high-K composite. As coating, STO effectively prevents the overlap and agglomeration of MWCNTs, thereby passivating the percolation threshold of the composite. STO increases the dielectric properties of the composite as a high dielectric ceramic. Under a low filler loading amount of 11 wt%, the dielectric constant and dielectric loss of the composite are 53 and 0.1, respectively. In addition, the composite can still maintain superior breakdown strength and mechanical properties, given the relatively low filler concentration. The enhanced dielectric properties, breakdown strength, and tensile strength make the composite suitable for application as dielectric material in flexible and stretchable energy storage equipment.