Enhancement of high-temperature dielectric energy storage performances of polyimide nanocomposites utilizing surface functionalized MAX nanosheets

High-temperature dielectric polymers have a broad application space in film capacitors for high-temperature electrostatic energy storage. However, low permittivity, low energy density and poor thermal conductivity of high-temperate polymer dielectrics constrain their application in the harsh-environment electronic devices, especially under elevated temperatures. Here, the combination of dopamine functionalized MAX (Ti3AlC2) nanosheets and a polyimide (PI) matrix offers a feasible strategy to prepare high-temperature polymer nanocomposites with improved dielectric and thermal performances. The surface functionalized MAX nanosheets with dopamine has guaranteed both the increase of dielectric constant and breakdown strength, leading to improved energy storage capability. As a result, the nanocomposite with 3 wt % functionalized MAX exhibits an enhanced energy density of 2.60 J/cm3 at 30 °C, and the nanocomposite with 1 wt % fillers possess an energy density of 1.19 J/cm3 at 100 °C, more than 1.32 and 1.18 times that of neat PI films (1.97 J/cm3 at 30 °C and 1.01 J/cm3 at 100 °C). In addition, an improved in-plane thermal conductivity of 0.55 W/(m·K) is obtained for PI based nanocomposite with 7 wt % [email protected], which is much higher than that of pure polymer (0.18 W/(m·K)). Our results show that surface modified MAX nanosheets can be used to construct polymer-based nanocomposites with excellent high-temperature energy storage capability and thermal properties.