Improved the High-temperature Energy Storage Performance of PI Films via Multi-scale Optimization of Electrodes and Interface Engineering

In modern power electronics, dielectric capacitors are vital for high-temperature energy storage. In the advancement of modern power electronics toward hightemperature and high-reliability applications, dielectric capacitors based on polyimide (PI) films are promising but face critical challenges from high conduction losses at elevated temperatures, restricting their energy storage performance. This study focuses on PI films and employs magnetron sputtering to deposit functional layers, including metal electrodes (Al, Cu, Pt) and inorganic barrier layers (Al₂O₃, SiO₂, PbZrO₃). By investigating electrode materials, diameters (3mm, 6mm, 9mm), and barrier layer compositions, it is found that Al electrodes dominate due to a native insulating Al₂O₃ layer, while 3mm diameter minimizes edge effects and defects. Al₂O₃-PI-Al₂O₃ films achieve a discharge energy density of 1.75 J/cm³ at 150°C (35% higher than pure PI) with excellent cycling stability. This work offers a scalable strategy for high-temperature dielectric capacitors in new energy and pulsed power systems.