Dielectric properties and energy‐storage performance of two‐dimensional molybdenum disulfide nanosheets/polyimide composite films

ABSTRACT Flexible dielectric materials with high electric energy density and high‐temperature resistant characteristic are of great importance for modern electronics and electrical systems. Herein, two‐dimensional molybdenum disulfide (MoS 2 ) nanosheets were efficiently produced via liquid‐phase exfoliation and then incorporated into polyimide (PI) to prepare MoS 2 /PI dielectric nanocomposites. Compared to the pristine PI, MoS 2 /PI nanocomposite films exhibited much larger dielectric permittivity while their dielectric losses still maintained relatively low levels. On the other hand, the Weibull breakdown strength of these nanocomposite films initially increased and then decreased with the increase in the MoS 2 content and gave rise to a maximum value of 395 MV m −1 at 1 vol % loading. Combination of the improved dielectric permittivity and breakdown strength makes the MoS 2 /PI nanocomposite film with 1 vol % MoS 2 possess an elevated energy density of about 3.35 J cm −3 . Moreover, good tensile and thermal properties of the nanocomposite films hold great promise for their applications in high‐temperature and harsh conditions. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 47991.