Metalla‐Aromatic Complexes Enhancing the High Temperature Energy Storage Performance of Polycarbonate Polymer

ABSTRACT Polymer dielectric capacitors are critical for advanced energy systems. However, their operation at high temperatures faces fundamental challenges: rising conduction losses and premature breakdown under extreme coupled thermal‐electric fields lead to deteriorated energy storage properties. In this study, the trade‐off between dielectric performance and high operating temperature is effectively addressed by strategically integrating metalla‐aromatic complexes (MACs) into the polycarbonate (PC) matrix. Unlike conventional π‐conjugated fillers, the osmium (Os)‐based complex MAC‐1 features a dual‐functional molecular design. Its electron‐deficient core, formed via Os‐ligand coordination, demonstrates exceptional charge‐trapping capability. The high oxidation state of Os and expanded 5 d orbitals generate a strong positive electrostatic potential, while d π ‐ p π conjugation redistributes electron density to further localize positive charge at the metal site. This quantum hybridization creates deep charge traps through intense electron delocalization. Concurrently, axially oriented triphenylphosphine (‐PPh 3 ) ligands establish steric barriers that physically suppress space charge migration. This synergy enables PC/MACs composites to achieve remarkable energy density (7.4 J cm −3 ) and discharge efficiency (93%) at 150°C, surpassing organic semiconductors (e.g., Indacenodithienothiophene‐based acceptor derivatives ITIC‐Cl: 6.0 J cm −3 ) with 85% higher synthetic yield. The demonstrated metal‐ligand coordination provides a new design method for high‐temperature dielectric composites while expanding MACs’ utility in next‐generation energy storage systems.