Ultrahigh Capacitive Energy Storage in a Heterogeneous Nanolayered Composite

Ferroelectric polymers with robust electrical polarization have been extensively investigated for capacitive energy storage. However, their inherent ferroelectric hysteresis loss limits the discharged energy density and compromises energy efficiency. Here, a heterogeneous nanolayered composite of ferroelectric polymer poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) and Al2O3 is presented, which effectively mitigates ferroelectric hysteresis loss while maintaining high polarization and enhanced breakdown strength. Phase-field simulations indicate that the polarization behaviors of the heterogeneous layered structure are jointly influenced by the thickness and dielectric constant of each component, which balances the electrical energy and Landau energy within the heterogeneous system. Guided by the theoretical simulations, optimized polarization behaviors are achieved with a significant reduction in remnant polarization and ferroelectric loss in the P(VDF-TrFE)/Al2O3 composites through careful control of P(VDF-TrFE) thickness at nanometer scale. Moreover, the presence of multiple interfaces in the layered composites leads to a remarkable enhancement in polarization and breakdown strength. Consequently, an ultrahigh energy density of about 108 J cm-3 is achieved with a high charge-discharge efficiency of exceeding 80%. This work not only presents a straightforward approach to modify the polarization behaviors of ferroelectric polymers but also demonstrates a promising strategy for developing high-energy-density polymer nanocomposites. The tunable electrical polarization behaviors of a heterogeneous nanolayered composite, composed of ferroelectric P(VDF-TrFE) and linear Al2O3, are demonstrated by adjusting the thickness of each component. The P(VDF-TrFE)/Al2O3 nanolayered composite with optimized polarizations presents an ultrahigh energy density of about 108 J cm-3 with a high energy efficiency of exceeding 80%, surpassing previous performance levels observed for both ferroelectric polymers and their composites. image