Probing the Interface Activation in Designing Defect-Free Multilayered Polymer Nanocomposites for Dielectric Capacitor Applications

Herein, we have successfully demonstrated the microstructural evidence of the inhomogeneous interfaces in multilayered capacitors and explained the role of interface activation in the dielectric performance. Robust and homogeneous interfaces in the barium titanate nanoparticles (BT NPs)/polyvinylidene fluoride (PVDF) polymer nanocomposites were developed using a polyvinylpyrrolidone (PVP) linker to link the top and bottom layers and a spin-coating approach. The cross-sectional field emission scanning electron microscopy depicted a clear picture of loosely bonded interfaces without PVP in a multilayered capacitor. The optimized PVP concentration (PVP2 = 30 mg mL(-1)) provided homogeneous interfaces. The energy density of PVDF-PVDF was the lowest among different devices, with a value of 1.6 J cm(-3) at 1872 kV cm(-1), and it was increased to 3.8 J cm(-3) at 3400 kV cm(-1) with PVP2 addition in PVDF-PVP2-PVDF. The 5 vol % BT NPs in BT/PVDF-PVP2-BT/PVDF (5 vol % BP2B) exhibited a maximum energy density of 6.2 J cm(-3) at a much higher breakdown field of 4474 kV cm(-1), which was similar to 100, similar to 300, and similar to 400% higher than those of PVDF, PVDF-PVDF, and state-of-the-art biaxially oriented polypropylene capacitors, respectively. Also, the trilayered device demonstrated a better dielectric performance than five-layered devices. Thus, the middle layer accompanies the interface homogeneity and eliminates the use of surface-functionalized nanofillers in a multilayered capacitor. This work will provide a mechanistic approach to develop low-cost, defect-free, and high energy density capacitors using a simple solution process route.