Synergistic ultrasound engineering of oxygen vacancies and piezoelectric fields in BaTiO3 for high-performance Li-CO2 batteries

The sluggish kinetics linked to CO 2 evolution reaction (CO 2 ER) processes, coupled with substantial electrode passivation, impose considerable constraints on the practical application of Li-CO 2 batteries. This study utilized ultrasound tech to enhance the synergistic modulation of defects and piezoelectric properties. By the concurrent creation of high-concentration oxygen vacancies (OVs) and the amplification of the inherent piezoelectric polarization field in BaTiO 3 material, the hysteresis of CO 2 ER processes and the occurrence of electrode passivation in Li-CO 2 batteries has been significantly improved. Further investigations reveal that high OV concentrations cause electronic structure reconstruction, leading to band gap contraction and Fermi energy level upshift, meanwhile, the augmented piezoelectric polarization field facilitates the directional migration of carriers, facilitating the growth of Li 2 CO 3 via the inherent electric field. Based on this synergistic mechanism, reversible decomposition of Li 2 CO 3 has been realized and Li-CO 2 cells with ultrasonic BTO cathode even exhibits a long cycle life of 375 cycles at the current density of 500 mA g −1 . This one-step physical field synergistic regulation of defect states in ferroelectric materials and their piezoelectric properties establishes a novel paradigm and mechanistic foundation for overcoming efficiency bottlenecks in piezoelectric catalytic systems and Li-CO 2 batteries.