A Bi‐Gradient Dielectric Polymer/High‐Κ Nanoparticle/Molecular Semiconductor Ternary Composite for High‐Temperature Capacitive Energy Storage

Abstract Attaining compact energy storage under extreme temperature conditions is of paramount importance in the development of advanced dielectric materials. The polymer composite approach has proved effective towards this goal, and addressing the correlation between filler distribution and electrical properties is foremost in designing composite dielectrics, especially in multifiller systems. Here, the design of a bi‐gradient polymer composite dielectric using an integrated framework based on the phase field model is reported. This framework can predict the charge‐inhibiting behavior of composite dielectrics, which is a key factor impacting the high‐temperature capacitive performance but unfortunately is ignored in conventional phase field models. It is found that due to the traps provided by the functional organic fillers, more carriers are trapped near the electrodes and weaken the electric field, thus significantly suppressing the breakdown initialization process. An interpenetrating gradient structure is designed rationally and synthesized experimentally, which exhibits concurrent high energy density (5.51 J cm−3) and high charge‐discharge efficiency (90%) up to 200 °C. This work provides a strategy to predict the high‐temperature energy storage performance of polymer composites containing charge‐inhibiting components and helps broaden the scope of data‐driven materials design based on phase‐field modeling.