Constructing Highly Thermally Conductive and Electrically Insulating Hybrid Network in Filling Materials for Cable Joint Cooling

Effective heat dissipation and electrical insulation are urgently required for filling materials of cable joints. Herein, we construct a thermally conductive and electrically insulating hybrid network consisting of aluminum oxide (Al 2 O 3 ) and boron nitride (BN) in polyurethane (PU)-based filling materials to meliorate the heat transfer ability for improved heat dissipation of cable joints. The resultant Al 2 O 3 /BN/PU composite displays an excellent thermal conductivity of 0.96 W/(m·K), outperforming Al 2 O 3 /PU composites by 84% at the total filler content of 25 wt%. The synergistic improvement of thermally conductive properties is ascribed to the fact that BN sheets bridge the gap among spherical Al 2 O 3 to form a large contact area for rapid phonon transmission. Infrared thermal images further demonstrate that the hybrid Al 2 O 3 /BN/PU composite has a stronger capacity to remove heat compared with the single Al 2 O 3 /PU composite. The electrical insulation, high mechanical strength, and thermal stability are also gathered. Our work paves a valuable way for designing and fabricating high-performance thermally conductive filling materials for effective cable joint cooling.