Enhanced energy storage in high-entropy ferroelectric polymers.

Relaxor ferroelectrics have been intensively studied during the past two decades for capacitive energy storage in modern electronics and electrical power systems. However, the energy density of relaxor ferroelectrics is fundamentally limited by early polarization saturation and largely reduced polarization despite high dielectric constants. To overcome this challenge, here we report the formation of a high-entropy superparaelectric phase in relaxor ferroelectric polymers induced by low-dose proton irradiation, which exhibits delayed polarization saturation, reduced ferroelectric loss and markedly improved polarizability. Our combined theoretical and experimental results reveal that new chemical bonds generated by the irradiation-induced chemical reactions are essential to the formation of the high-entropy state in ferroelectric polymers. The high-entropy superparaelectric phase endows the polymer with a substantially enhanced intrinsic energy density of 45.7 J cm at room temperature, outperforming the current ferroelectric polymers and nanocomposites under the same electric field. Our work widens the high-entropy concept in ferroelectrics and lays the foundation for the future exploration of high-performance ferroelectric polymers.