Leakage-proof nacre-like boron nitride nanosheet/phase change microcapsule composites with enhanced thermal conduction and thermal energy storage for advanced thermal management systems

Abstract

Thermal conduction enhancement and thermal energy storage are often solely or synergistically adopted to build advanced thermal management systems for the high-standard heat dissipation requirements of advanced electronic devices. However, the “trade-off” effect between thermal conduction and thermal energy storage as well as the safety issues caused by leakage of liquid phase change materials should be addressed for the construction of efficient, stable, and safe thermal management systems. Herein, boron nitride nanosheets (BNNSs) and phase change microcapsules (PCMCs) were deliberately selected as building blocks to fabricate nacre-like BNNS/PCMC composites integrating enhanced thermal conduction with thermal energy storage via sequential bidirectional freezing and hot-pressing techniques. The leakage-proof property of the BNNS/PCMC composites was addressed by the double encapsulation of paraffin by the capsule shell and porous boron nitride skeleton. The isotropic and in-plane thermal conductivities, as well as thermal energy storage of BNNS/PCMC composites, could be delicately adjusted via the BNNS/PCMC ratio and type of PCMCs, within the range of 1.14–7.96 W m⁻¹ K⁻¹ and 2.38–17.71 W m⁻¹ K⁻¹, as well as 72–183 J g⁻¹, respectively. The enhanced thermal conduction could be ascribed to the ordered arrangement of interconnected BNNSs in the BNNS/PCMC composites. The BNNS/PCMC composites with various phase change temperatures were fabricated to match the operating temperatures and heat dissipation requirements of versatile electronic devices. This work provides insights into the structural design and controllable fabrication of thermal management systems with superior thermal conduction and thermal energy storage.