A novel lead-free and high-performance barium strontium titanate-based thin film capacitor with ultrahigh energy storage density and giant power density†
High-performance lead-free film capacitors with simultaneously large energy storage density and high power density are strongly demanded in applications. Here, a novel relaxor-ferroelectric 0.88Ba0.55Sr0.45TiO3–0.12BiMg2/3Nb1/3O3 (BST–BMN) thin film capacitor was obtained with an ultrahigh recoverable energy storage density (Wrec) of ∼86 J cm−3 and high efficiency of ∼73% under the dielectric breakdown strength of 5 MV cm−1. In addition, the investigated thin film capacitor exhibited an excellent fatigue resistance property with the Wrec variation less than ∼2% after 107 cycles. More importantly, a considerable power density of ∼208 MW cm−3 was obtained in BST–BMN thin film capacitors, which is superior to many other thin film capacitors. These remarkable performances should be attributed to the simultaneously enhanced BDS and relaxor behavior through the incorporation of non-isovalent ions. These results qualify the environment-benign BST–BMN thin films as promising candidates for energy storage applications and promote the development of BST-based film capacitors with enhanced Wrec in the future.