Interface‐Engineered BN/MXene Composites for Anisotropic Thermal Conduction and Solid‐Solid PCM Buffering

ABSTRACT The rational design of phase‐change composites that simultaneously deliver high thermal conductivity, intrinsic electrical insulation, and structural integrity is crucial for advanced thermal management and energy‐regulation technologies. Herein, we report an interface‐engineered anisotropic hybrid aerogel composed of amine‐functionalized boron nitride ( f ‐BN) and Ti 3 C 2 T x MXene, fabricated via a dual‐polymer‐assisted gelation strategy combined with directional freeze‐casting. By engineering chemically bonded yet electrically insulating interfaces through B‐N‐NH 2 bridges, Ti‐O‐C/N linkages, and π – π interactions, the system establishes a phonon‐dominated transport network that overcomes the intrinsic trade‐off between thermal conduction and electrical insulation. The aligned lamellar architecture further promotes efficient through‐plane heat transport. Upon incorporation into a polyurethane‐based solid‐solid phase‐change matrix, the composite achieves a high thermal conductivity of 3.376 W m −1 K −1 at a low filler loading of 14 wt.%, while retaining a substantial latent heat of 108 J g −1 and high electrical resistivity (1.68 × 10 12 Ω·cm). The composite exhibits excellent cycling stability (>96% retention after 100 thermal cycles) and delivers significant temperature reductions in CPUs (10.0°C) and Li‐ion battery modules (≈7.6°C). This work establishes a design paradigm for electrically insulating, high‐performance phase‐change composites with synergistic heat transport and energy buffering.