Enhanced Energy Storage Performance of Lead-Free Capacitors in an Ultrawide Temperature Range via Engineering Paraferroelectric and Relaxor Ferroelectric Multilayer Films

• Published in: ACS applied materials & interfaces Vol. 12; no. 23; pp. 25930 - 25937
• Main Authors: Hu, Tian-Yi, Ma, Chunrui, Dai, Yanzhu, Fan, Qiaolan, Liu, Ming, Jia, Chun-Lin
• Format: Journal Article
• Language: English
• Published: United States 10.06.2020
• Subjects: lead-free thin film; energy storage; high temperature; relaxor ferroelectrics; paraelectrics
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.0c05560

Industry has been seeking a thin-film capacitor that can work at high temperature in a harsh environment, where cooling systems are not desired. Up to now, the working temperature of the thin-film capacitor is still limited up to 200 °C. Herein, we design a multilayer structure with layers of paraferroelectric (Ba Sr TiO , BST) and relaxor ferroelectric (0.85BaTiO -0.15Bi(Mg Zr )O , BT-BMZ) to realize optimum properties with a flat platform of dielectric constant and high breakdown strength for excellent energy storage performance at high temperature. Through optimizing the multilayer structure, a highly stable relaxor ferroelectric state is obtained for the BST/BT-BMZ multilayer thin-film capacitor with a total thickness of 230 nm, a period number N = 8, and a layer thickness ratio of BST/BT-BMZ = 3/7. The optimized multilayer film shows significantly improved energy storage density (up to 30.64 J/cm ) and energy storage efficiency (over 70.93%) in an ultrawide temperature range from room temperature to 250 °C. Moreover, the multilayer system also exhibits excellent thermal stability in such an ultrawide temperature range with a change of 5.15 and 12.75% for the recoverable energy density and energy storage efficiency, respectively. Our results demonstrate that the designed thin-film capacitor is promising for the application in a harsh environment and open a way to tailor a thin-film capacitor toward higher working temperature with enhanced energy storage performance.