Superior Energy Storage Performance in a Self-Organized Trirelaxor-Antiferroelectric Nanocomposite Over a Wide Temperature Range

A fundamental paradox in energy storage dielectrics lies in the challenge of achieving superior performance consistently across both room and elevated temperatures. This is addressed by designing a self-organized nanocomposite (1−x)(Ba,Sr)(Ti,Sn)O₃-xBi_1.5ZnNb_1.5O₇ composed of nano-sized antiferroelectric(AFE) particles embedded into a trirelaxor(TRE) matrix through nanoscale phase separation process. The optimal composition at x = 0.11 exhibits outstanding energy storage performance from room temperature (energy density = 8.5 J cm⁻³, efficiency = 94.8%, and figure of merit of 167 J cm⁻³) up to 200 °C (energy density = 4.85 J cm⁻³, efficiency >90% and figure of merit of 49 J cm⁻³), outperforming existing Pb-free dielectrics. High-resolution transmission electron microscopy and synchrotron x-ray diffractometry reveal that the coexisting nanometric antiferroelectric particles and the trirelaxor nanodomains sustain over a wide temperature range. Piezoresponse force microscopy and phase-field simulation show that hysteresis-free switching of trirelaxor nanodomains enables enhanced polarization and low hysteretic loss. Resistivity shows a 2–3 order of magnitude increases accompanying significant increase in breakdown strength up to high temperatures, attributable to deep charge trapping effect at high-density TRE/AFE interfaces as evidenced by thermally stimulated depolarization current. These favorable effects in the nano-composite are responsible for its high energy storage performance up to high temperatures.