Improved breakdown strength and electrical energy storage performance ofγ-poly(vinylidene fluoride)/unmodified montmorillonite clay nano-dielectrics

A remarkable improvement in the dielectric breakdown strength (Eb) and discharge energy density (U e) of flexible polymer nanocomposites is realized by the incorporation of unmodified smectite montmorillonite (MMT) nanoclay into a poly(vinylidene fluoride) (PVDF) matrix. The resulting PVDF/MMT clay nanocomposite (PCN) films stabilize the γ phase and increase the path tortuosity via strong intercalation of the PVDF matrix into inorganic layered silicates without sacrificing the quality of surface morphology. The PCN films exhibits superior dielectric properties (up to ε r ∼ 28 and tan δ ∼ 0.032 at 1 kHz) than those of pure PVDF. As a result, a large increase in E b of 873 MV m(-1) and U e of 24.9 J cm(-3) is achieved. Subsequently, the PCN films possess more than 60% charge-discharge efficiency even at higher electric field and thus provide a scope to develop high energy density flexible and transparent materials for energy storage technologies.