Wide Band Gap Boron Nitride Nanodots‐Incorporated Polyetherimide Dielectrics for High‐Temperature Dielectric Energy Storage

With the ongoing trend toward miniaturization in electronic devices and the concomitant increase in power density, the operational requirements for dielectric polymer films have extended beyond conventional room-temperature conditions. In this study, low mass fraction boron nitride nanodots (BNNDs) were incorporated into polyetherimide (PEI) films. The strong π-π interaction between BNNDs and PEI enables BNNDs to effectively intercalate between adjacent PEI molecular chains, thereby effectively weakening the interchain conjugation effects within the PEI matrix, successfully suppressing energy losses at high temperatures. Consequently, the composite film achieved an exceptional breakdown strength (E_b) of 549.4 MV m^-1 at 200°C while maintaining discharge energy density (U_d) of 6.49 J cm^-3 and efficiency (η) of 65%. Furthermore, the film demonstrated notable self-healing capability following dielectric breakdown, at 200°C and 500 MV m^-1, the U_d values before and after breakdown were 4.88 and 4.24 J cm^-3, respectively, with η of 85% and 82%. In summary, this study demonstrates the existence of strong π-π conjugated interactions between BNNDs and PEI molecular chains. Consequently, BNNDs can intercalate between PEI molecular chains, replacing the π-π conjugation between these chains, thereby enhancing the high-temperature performance of aromatic dielectric polymers.