A Facile Pre-Lithiated Strategy towards High-Performance Li₂Se-LiTiO₂ Composite Cathode for Li-Se Batteries

Conventional lithium-ion batteries with a limited energy density are unable to assume the responsibility of energy-structure innovation. Lithium-selenium (Li-Se) batteries are considered to be the next generation energy storage devices since Se cathodes have high volumetric energy density. However, the shuttle effect and volume expansion of Se cathodes severely restrict the commercialization of Li-Se batteries. Herein, a facile solid-phase synthesis method is successfully developed to fabricate novel pre-lithiated Li₂Se-LiTiO₂ composite cathode materials. Impressively, the rationally designed Li₂Se-LiTiO₂ composites demonstrate significantly enhanced electrochemical performance. On the one hand, the overpotential of Li₂Se-LiTiO₂ cathode extremely decreases from 2.93 V to 2.15 V. On the other hand, the specific discharge capacity of Li₂Se-LiTiO₂ cathode is two times higher than that of Li₂Se. Such enhancement is mainly accounted to the emergence of oxygen vacancies during the conversion of Ti⁴⁺ into Ti³⁺, as well as the strong chemisorption of LiTiO₂ particles for polyselenides. This facile pre-lithiated strategy underscores the potential importance of embedding Li into Se for boosting electrochemical performance of Se cathode, which is highly expected for high-performance Li-Se batteries to cover a wide range of practical applications.