Superior High‐Temperature Energy Storage Capacity Enabled by Silicone‐PAEK Hybrid Dielectrics

The rapid development of power equipment has created an urgent demand for polymer dielectrics capable of withstanding high temperatures (>150°C). Traditional high‐temperature‐resistant materials featuring conjugated rigid backbones often suffer from high leakage currents and low energy density ( U e ) at elevated temperatures. This work introduces an element hybridization strategy that incorporates insulating and flexible siloxane units into the poly(aryl ether ketone) (PAEK) backbone. The siloxane units disrupt the conjugated continuity of PAEK, enabling the dielectric to maintain a wide and stable band gap, while their Si─O bonds exhibit substantial field‐induced distortion to drive polarization enhancement. Concurrently, the vacant orbitals of silicon atoms form deep electron traps, reducing the leakage current by an order of magnitude. As a result, c‐P(AEK‐DMS) containing 10% siloxane units achieves an ultrahigh U e of 7.43 J·cm −3 with a discharging efficiency of 90% at 150°C, representing a 253% improvement over PAEK. In addition, c‐P(AEK‐DMS) maintains excellent energy‐storage performance after self‐healing, highlighting its potential for long‐term operational reliability. This study presents an effective element‐hybridization design for crosslinkable PAEK dielectrics and provides useful insights into balancing high‐temperature energy storage and reliability‐related performance.