Breakthrough energy storage in medium-entropy superparaelectrics by triple synergy strategy

High-performance dielectric ceramic capacitors hold immerse potential for advanced electronics and high-power electrical systems. However, achieving both high recoverable energy density (W_rec) and high energy efficiency (η) remains a critical challenge in bulk dielectric ceramics. Herein, we propose a triple-synergistic strategy that integrates medium-entropy superparaelectric design, local structural distortion, and plate-like secondary bismuth titanate phase construction in SrTiO₃-based dielectric ceramics. This approach effectively promotes the formation of polymorphic polar nano-regions with short-range polar vectors, enhancing dynamic polarization response. Simultaneously, the introduction of a plate-like secondary bismuth titanate phase within the perovskite matrix significantly increases the breakdown field strength (E_b) by inhibiting breakdown-path propagation. The resulting medium-entropy superparaelectric exhibits a nearly hysteresis-free P-E loop, combined with an ultrahigh E_b and high polarization. Notably, the material achieves a remarkable W_rec of 10.31 J/cm³ along with an ultrahigh η of 90.9%. Furthermore, it demonstrates outstanding charge/discharge performance, excellent thermal stability and robust cycling stability, making it a highly promising candidate for energy storage applications. This study provides a feasible and innovative design strategy for high-performance bulk dielectrics, paving the way for the development of eco-friendly dielectric capacitors for next-generation energy storage systems.