Bidirectional thermal-electrical energy conversion system based on ferroelectrics: A review

Finding a green, efficient, and reliable system that can convert heat into electricity, or vice versa, is a key challenge of this century. Ferroelectrics exhibit both pyroelectric and electrocaloric effects, enabling direct and reversible conversion between thermal and electrical energy. This dual functionality offers a promising pathway to integrate power generator and heat pump within a single system, which could potentially address challenges associated with low energy utilization efficiency and carbon-emission reduction in generating electricity or pumping heat. This review presents an overview of the fundamental principles associated with the pyroelectric and electrocaloric effects, followed by a comprehensive summary of recent progress in high-performance ferroelectric materials for thermal-electrical energy conversion, including ceramics, polymers, and emerging material systems. The review also discusses the operational cycles, heat transfer modes, representative laboratory prototypes, and circuit design of both pyroelectric power generators and electrocaloric heat pumps. Progress in materials, device architecture, and energy recovery circuits is expected to play a critical role in translating next-generation thermal-electrical energy conversion devices from laboratory demonstrations to practical and large-scale applications.