Ultrathin Functional 2D Nanosheets Promote Energy Storage Performance of BNNS/PP Nanocomposites

Polypropylene (PP), currently the most widely used dielectric material of capacitors, faces a big challenge for advanced electronic and electrical systems, due to its relatively low energy storage performance. In this paper, we presented a straightforward and efficient solution by introducing hydroxylated boron nitride (BNNS-OH), the two-dimensional (2D) broadband nanosheets with surface modification, into the PP matrix. Charge carriers could be captured and confined in nanocomposites, showing the 'barrier effect' of 2D wide bandgap nanosheets. Consequently, the leakage current of the PP-based nanocomposites was suppressed, and a synergistic improvement in breakdown strength (E_b) and charge-discharge efficiency (η) was achieved. When 5 wt% BNNS-OH were incorporated, BNNS-OH/PP nanocomposites maintained a high discharged energy density of 2.65 J/cm³ (with η above 90%), which was 2.4 times higher than that of the pure PP film.