Super‐Paraelectric Regulation of Energy Storage Performance in Sm 2 O 3 ‐Doped (Ba,Sr)TiO 3 Films via Nanostructure Engineering

This work presents a strategy for enhancing the energy storage performance in BaTiO 3 ‐based nanocomposite films through a super‐paraelectric regulation approach enabled by Sm 2 O 3 doping. The proposed lead‐free (1‐ x )(Ba 0.8 Sr 0.2 )TiO 3 ‐ x Sm 2 O 3 (0.0 ≤ x ≤ 0.5) films contain only five elements, making them environmentally friendly and simple in composition. The incorporation of Sm 2 O 3 as an immiscible second phase within the (Ba 0.8 Sr 0.2 )TiO 3 matrix induces significant chemical and structural heterogeneity, inducing a transition from a conventional ferroelectric state to a super‐paraelectric state. In combination with an enhanced breakdown strength, this design results in an ultrahigh energy storage efficiency ( η ) exceeding 80%, along with a remarkable recoverable energy storage density ( U e ) of 50.6 and 59.2 J/cm 3 at Sm 2 O 3 contents of x = 0.4 and 0.5. Furthermore, the films with x = 0.4 and 0.5 exhibit superior frequency (20 Hz to 5 kHz) and thermal stability (25°C–160°C), highlighting exceptional operational reliability and robustness under varying conditions. This study demonstrates that the proposed super‐paraelectric regulation strategy provides a practical pathway for designing compositionally optimized and eco‐friendly energy storage materials.