Graphitic-carbon nitride nanosheets as a new inorganic filler for improving energy storage density of PVDF-based dielectric composites

Graphitic-phase carbon nitride (g-C₃N₄) nanosheets with lateral size of 1000 nm, 500 nm, and 100 nm have been fabricated by a one-step thermal condensation method at different thermal treating temperatures and used as filler for poly(vinylidene fluoride) (PVDF)-based dielectric composites. The effects of its size and content on energy storage density of g-C₃N₄/PVDF composites are discussed. The experimental results show that the energy storage density of the composites containing 3 wt% g-C₃N₄ increases with the decrease of lateral size and could reach to 11.7 J cm⁻³ at 522 kV mm⁻¹, much higher than pure PVDF of 5.8 J cm⁻³ at 386 kV mm⁻¹. A finite element simulation is employed to describe electric field distribution within the composites and reveal further the role of g-C₃N₄ nanosheets on the energy storage behavior of the composites. This work provides a new inorganic filler for high energy storage density PVDF-based dielectric composites.