Progress and outlook on lead-free ceramics for energy storage applications

With the rapid development of economic and information technology, the challenges related to energy consumption and environmental pollution have recently intensified. Faced with this increasingly severe situation, significant attention has been devoted to developing novel and environmentally friendly materials for energy conversion and storage. Among various energy conversion and storage systems, lead-free ceramic dielectric capacitors emerge as a preferred choice for advanced pulsed power devices due to their high power density, excellent thermal stability, long service lifespan, and environmental friendliness. Despite enormous efforts, the energy storage density and efficiency of most lead-free ceramics still lag behind Pb-based ceramics and polymer-based dielectrics, limiting their practical applications. Regarding ceramic dielectrics used in advanced pulsed power systems, parameters such as a moderate dielectric constant, high electric breakdown strength, large maximum polarization (or saturation polarization), and low remnant polarization are of crucial importance. To better promote the development of lead-free ceramics with superior energy storage properties, we summarized the progress in lead-free ceramics for energy storage applications in this review. This includes exploring the energy storage mechanisms of ceramic dielectrics, examining the typical energy storage systems of lead-free ceramics in recent years, and providing an outlook on the future trends and prospects of lead-free ceramics for advanced pulsed power systems applications.