Enhancing the performance of BaTi0.89S0.11O3/PVDF-HFP composites through tailored functionalization of barium stannate titanate (BaTi0.89S0.11O3) fillers

Nanocomposites are currently attracting significant attention in the energy sector, particularly for storage applications. However, controlling interfacial compatibility remains a challenge. This work introduces a novel interfacial functionalization strategy that enables the achievement of exceptional dielectric properties and addresses the persistent issue of poor filler–matrix interaction in nanocomposites. A poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) matrix was filled with lead-free BaTi_0.89Sn_0.11O₃ (BTS₁₁) nanoparticles, which exhibit ultra-high piezoelectric performance near ambient temperature. These nanoparticles were functionalized with various modifying agents, including ethylenediamine (EDA), polyvinylpyrrolidone (PVP), polydopamine (PDA), and 3-aminopropyltriethoxysilane (APS). The study demonstrated that the functionalized HO-BTS₁₁@modifier/PVDF-HFP nanocomposites exhibit distinct dielectric characteristics depending on the modifying agent. The HO-BTS₁₁@EDA/PVDF-HFP nanocomposites, which included hydroxylated HO-BTS₁₁ nanoparticles modified with EDA, outperformed other modified systems with the maximum energy storage efficiency (~ 77%) and a dielectric permittivity of 70 at 1 kHz. EDA with small molecular size, low polarity, and ability to form hydrogen bonds enable improved interfacial adhesion with the hydrophobic PVDF-HFP matrix making the composite suitable for enhancing energy storage performance. This selective functionalization strategy not only provides new insights into interface engineering but also offers a promising pathway for the development of high-performance materials for energy storage and harvesting devices, embedded capacitors, flexible electronics, and next-generation dielectric systems.