Scalable Polyimide‐Organosilicate Hybrid Films for High‐Temperature Capacitive Energy Storage

Abstract

well drilling. [1][2][3] Nowadays, dielectric materials with excellent high-temperature capacitive properties are in great demand because of the heat inevitably generated by compact high-power electronic systems. [4][5][6][7] For example, the operating temperature of capacitors is 140-150 °C in green-energy vehicle inverters and reaches 200 °C in electrified aircraft. Biaxially oriented polypropylene (BOPP), the mainstream commercial polymer dielectrics, has discharged energy densities (U e ) <4.0 J cm −3 and a maximum operating temperature below 105 °C. [5,8,9] Therefore, developing dielectric polymers with high working temperatures and large energy storage densities is of critical importance.The current high glass-transitiontemperature (T g ) dielectric polymers, including polyimide (PI), polyetherimide (PEI), polyetheretherketone (PEEK), and fluorene polyester (FPE), usually exhibit low breakdown strength (E b ) and poor capacitive performance at >150 °C because of an exponential increase in conduction loss with the applied field and temperature. [5,10,11] There are two types of conduction mechanisms in dielectrics, i.e., electrode-limited and bulk-limited conduction mechanisms. [6,[12][13][14][15][16][17] Unlike the electrode-limited conduction mechanism that depends on the electrode-dielectric interface, the bulk-limited conduction mechanism is determined by the electrical characteristics High-temperature polymer dielectrics have broad application prospects in next-generation microelectronics and electrical power systems. However, the capacitive energy densities of dielectric polymers at elevated temperatures are severely limited by carrier excitation and transport. Herein, a molecular engineering strategy is presented to regulate the bulk-limited conduction in the polymer by bonding amino polyhedral oligomeric silsesquioxane (NH 2 -POSS) with the chain ends of polyimide (PI). Experimental studies and density functional theory (DFT) calculations demonstrate that the terminal group NH 2 -POSS with a wide-bandgap of E g ≈ 6.6 eV increases the band energy levels of the PI and induces the formation of local deep traps in the hybrid films, which significantly restrains carrier transport. At 200 °C, the hybrid film exhibits concurrently an ultrahigh discharged energy density of 3.45 J cm −3 and a high gravimetric energy density of 2.74 J g −1 , with the charge-discharge efficiency >90%, far exceeding those achieved in the dielectric polymers and nearly all other polymer nanocomposites. Moreover, the NH 2 -POSS terminated PI film exhibits excellent charge-discharge cyclability (>50000) and power density (0.39 MW cm −3 ) at 200 °C, making it a promising candidate for high-temperature high-energy-density capacitors. This work represents a novel strategy to scalable polymer dielectrics with superior capacitive performance operating in harsh environments.

Thermally activated dynamic bonding network for enhancing high-temperature energy storage performance of PEI-based dielectrics

“…[4][5][6][7][8] In practical applications, dielectric capacitors are always exposed to harsh environments, and their operating temperature always exceeds 140 1C. 9,10 However, the maximum operating temperatures of the current used commercial dielectric polymers are usually below 100 1C. 11,12 Therefore, it is critical to develop polymers with excellent reliability and stability at high-temperature.…”

Enhanced High-Temperature Capacitive Energy Storage by 0.55Bi0.5Na0.5TiO3-0.45(Bi0.2Sr0.7)TiO3 Nanofibers in Polyetherimide Nanocomposites

“…Polymer-based dielectric materials have high losses under high electric fields or high temperatures, and the losses will sharply increase with the applied temperature and electric field, which will lead to a decrease in U dis and efficiency. − The commonly used biaxially oriented polypropylene film in commercial applications has a U dis of 2–3 J/cm 3 and can withstand operating temperatures of less than 85 °C. − Polyetherimide (PEI) is a thermoplastic engineering resin with high glass transition temperature, excellent breakdown field strength, mechanical properties, and high temperature stability. − Lin et al prepared high-entropy-induced ceramic nanofibers as a filler by electrospinning to enhance the energy storage performance of PEI. Due to the refined grain size, linear pyrochlore phase, and increased amorphous fraction of nanofillers, composites exhibit significantly enhanced U dis over the temperature range of 25–150 °C …”

Tailoring Organic/Inorganic Interface Trap States of Metal Oxide/Polyimide toward Improved Vacuum Surface Insulation

“…Polyimide (PI) films are commonly used for external insulation of a spacecraft as they are resilient to the high applied voltage, thermally stable, lightweight, and versatile for a range of working conditions, such as the external layer of multilayer thermal blankets, insulating substrate of solar arrays, cable, and so on. − Spacecraft operations are prone to anomalies due to the harsh space environment including ultra-high vacuum, high-energy beam, radiation, and thermal cycling. − It is reported that more than half of the spacecraft anomalies (i.e., 54.2%) from the total 299 recorded cases were caused by the spacecraft charging and discharging effects, such as the net charge accumulation, induction of surface potential, and electrostatic discharges (ESD) caused by energetic particles. , These detrimental phenomena not only lead to the degradation of insulating materials but also perturb the telecommunication and electronic systems of the spacecraft, seriously threatening the reliability of the on-orbit spacecraft missions. − Particularly, ESDs on the surface of the spacecraft, especially on solar arrays, has become one of the primary causes of on-orbit power system failures in spacecrafts. − …”