Composite dielectric capacitors with chemically functionalized BaTiO3 nanoparticles

Capacitors are electronic components consisting of metal electrodes separated by an insulating material that store electrical energy through an electric field. They are used in applications requiring short bursts of energy, or for balancing the voltage fluctuations during charge-discharge cycles depending on the grid conditions, which is particularly important to ensure the stable and reliable operation of electronic devices. The miniaturization of these components with improved energy density would allow for weight and space savings in emerging electronic technologies. Traditional polypropylene (PP)-based capacitors suffer from low temperature tolerance and energy density. Thus, capacitors containing nanoceramic particles with high permittivity and a polymer matrix with high breakdown strength have been proposed to solve this problem. However, these nanoparticles may agglomerate, causing uneven distribution within the material and a short-circuit. The driving force of agglomeration may originate from the high surface area and surface energy of nanomaterials. Thus, the chemical functionalization of nanoparticles has emerged as a promising approach to increase dispersibility, enhance capacitance, and achieve higher energy density.
This work focuses on the search for an efficient chemical functionalization method for barium titanate nanoparticles as an additive for PP film capacitors. The nanoparticles were functionalized through surface coating with surfactants, hydroxylation to enhance the oxygen-containing chemical groups, and covalent bonding with the organic surface modifiers. The modified nanoparticles were dispersed in a polypropylene gel, which was assessed with Dynamic light scattering (DLS). Then, thin-layer capacitor devices were prepared using the composition by spin-coating. Scanning electron microscopy with energy-dispersive x-ray spectroscopy (SEM-EDX) was used to observe the cross-sections of the polypropylene composites to study the distribution of BaTiO3 nanoparticles. The effectiveness of the treatments on devices’ energy storage capabilities was assessed by measuring the capacitance, resistance and breakdown voltage.
Overall, this work explicates the importance of chemical functionalization as a key strategy to enhance energy density and reliability of dielectric composite capacitors. The advancements in this field are paving the way for the development of high-performance capacitors to meet the increasing demands of modern electronics, energy storage systems, and power electronics applications.