Effect of PMMA on the Energy Storage Properties of PVDF‐Based Polymer Dielectrics Doped with 2D Nanosheets

ABSTRACT Ternary composite dielectric films of PMMA/g‐C 3 N 4 /PVDF were prepared using a simple solution casting method. The small difference in dielectric constant between the graphite phase (g‐C 3 N 4 ) and polyvinylidene fluoride (PVDF) reduces local electric field distortion. The g‐C 3 N 4 is a ditopic nanomaterial with low conductivity and a wide bandgap. This property can significantly enhance the breakdown strength of composites. The amorphous polymer poly(methyl methacrylate) (PMMA) is interspersed within the PVDF molecular chain. This disrupts its orderly arrangement, reducing its crystallinity and decreasing its grain size. The crystallinity of the 60% PMMA/3% g‐C 3 N 4 /PVDF composite film decreased to 23.36%, and the grain size was reduced to 5.6 nm. Meanwhile, the addition of PMMA hindered the movement of mobile charges, reducing the leakage current of the composite material to 5.28 × 10 − ⁷ A/cm 2 and effectively lowering the probability of breakdown. Research indicates that the breakdown strength of the PMMA/3% g‐C 3 N 4 /PVDF composite material achieves 563.81 MV/m when the PMMA content reaches 50 %, representing an approximately twofold improvement over PVDF. Its energy storage density also reaches 6.58 J/cm 3 at this point.