The present study meticulously investigates the energy storage and electrocaloric performance of the \((1-x)\) Ba0.5Sr0.5TiO3– \(x\) Bi0.5Na0.5TiO3(BST5–BNT) ceramics with varying BNT compositions. The materials were synthesized using solid-state reaction method (SSR). The crystallographic structure along with the phase purity of the ceramics was confirmed through X-ray diffraction (XRD). Field emission scanning electron microscopy (FE-SEM) images were analyzed carefully to understand the distribution of the grains. The frequency and temperature-dependent dielectric response indicates the relaxor behavior of the studied BST5–BNT ceramics. XPS analysis provides an insight into the surface chemistry of the ceramics and it is observed that with the addition of BNT, there is a possibility of oxygen vacancy enhancement leading to a better grain growth and improved energy storage properties. For all the compositions, the room-temperature energy storage capacities were evaluated from the ferroelectric polarization–electric field (P–E) loop studies. The \((1-x)\) BST5– \(x\) BNT ceramic with \(x=0.4\) exhibits a higher energy storage density of 0.468 J/cm3 with an efficiency of 84% at room temperature. Subsequently, in order to study the electrocaloric effect (ECE), the temperature-dependent P–E loops were analyzed thoroughly. The ECE calculations were carried out via indirect method on the basis of Maxwell’s thermodynamical relation. A maximum adiabatic temperature change ( \(\Delta T\) max) of 0.31 K and an electrocaloric responsivity of \(\xi\) max = 0.16 K mm/kV are achieved for \(x=0.4\) ceramic near room temperature under a moderate electric field of 20 kV/cm.
