Langmuir–Blodgett assisted alignment of 2D nanosheets in polymer nanocomposites for high-temperature dielectric energy storage applications

Dielectric polymers with inherent flexibility, high breakdown strength, and low cost have garnered significant attention for their potential applications as energy storage mediums in advanced electronic and electrical systems. However, these current polymers exhibit a low dielectric constant and inferior thermal stability, resulting in a low energy density and limited operation temperature. In this work, we present a Langmuir–Blodgett (LB) technique-assisted approach for achieving a multilayered polyetherimide (PEI)/calcium niobate (CNO) nanocomposite with in-plane aligned CNO nanosheet layers embedded within the polymer matrix. The LB deposition technique enables a precise in-plane alignment and a densely packed arrangement of CNO nanosheets within the PEI matrix, thereby effectively impeding charge transfer and establishing a continuous heat-conducting network. Consequently, the multilayered PEI/CNO nanocomposite exhibits a significant reduction in leakage current density and an enhancement in breakdown strength at elevated temperatures compared to the pure PEI polymer. Additionally, the incorporation of CNO nanosheets also leads to an increase in the dielectric constant of the nanocomposites. Due to these improvements in the dielectric constant and high-temperature breakdown strength, the multilayered nanocomposite achieves a remarkable 180% enhancement in energy density compared to pure PEI, reaching 6.9 J cm−3 at 150 °C (with an energy efficiency exceeding 90%). Furthermore, the nanocomposite film-based multilayer polymer capacitor (MLPC) device exhibits exceptional capacitance and outstanding flexibility, showcasing the immense potential of these multilayered nanocomposite films in high-temperature electronic and electrical systems.