Enhancement of boron nitride nanosheet/cellulose nanofiber modified laminated insulating paper

The extra-high voltage casing faces severe heat dissipation demands during operation, which places higher requirements on the thermal conductivity, mechanical properties, and electrical properties of insulating paper in the oil-paper insulation system. However, enhancing the overall performance of materials by only using a single nanomaterial remains a significant challenge. Consequently, this paper proposes integrating laminate design with nanomaterial doping modification to engineer boron nitride nanosheet/cellulose nanofiber (BNNS/CNF) modified laminated composite insulating paper. The synergistic effect of BNNS and CNF leads to a notable enhancement in the mechanical properties of the insulating paper, with the tensile strength increasing by up to 20.4%. The BNNS, CNF, and cellulose are arranged layer by layer under gravity to form a “brick mud” structure, which synergistically constitutes a thermal conductivity network, and the thermal conductivity is increased by up to 15.82%. In addition, the laminate structure and nanofillers optimize the electric field distribution inside the modified paper, thereby enhancing the DC breakdown field strength by 22.36% and reducing the power frequency dielectric loss by 52.51%. The laminated boron nitride nanosheet/nanocellulose modified insulating paper exhibits excellent overall performance, positioning it as a promising cellulose-based insulating paper material with significant potential.