Fig. 1: Design of polymorphic heterogeneous shell by phase-field simulation for ultrahigh energy storage.

Comparative display of domain structures, polarization configurations, and normalized P-E loops with different heterostructures including a Polar core with microdomain shell, b Polar core with nanodomain shell, and c Polar core with polymorphic heterogeneous shell. The light green rectangles represent the enlarged domain structure or local polarization configuration in the shell.