Dual-ion (de)intercalation into high-entropy perovskite oxides for aqueous alkaline battery-supercapacitor hybrid devices

High-entropy perovskite oxides (HEPOs) suffer from inferior stability in high-power battery-supercapacitor hybrid (BSH) devices. Therefore, revealing their energy storage mechanism is extremely important for optimizing appliance stability. Herein, La0.7Bi0.3Mn0.4Fe0.3Cu0.3O3 nano-HEPO exhibits the dual-ion energy storage mech-anism in aqueous alkaline BSH devices. The rapid deintercalation of oxygen anions from the (sub)surface fa-cilitates the intercalation of hydrogen cations into the bulk during charging; however, the deintercalation of hydrogen cations upon the discharge process is hindered because of the surface filling with oxygen vacancies, resulting in an irreversible phase transition and volumetric expansion. Meanwhile, the evolution of surface oxygen species leads to the weak binding between the surface metal-oxygen polyhedron and the bulk, causing severe capacity deterioration due to the active cation leaching and surface inactive La(OH)3 aggregation. Finally, optimal strategies are presented based on the dual-ion intercalation chemistry of HEPOs for application in high -performance BSH devices with long service life.

Automated summary

High-entropy perovskite oxides (HEPOs) have unstable energy storage in high-power battery-supercapacitor hybrid devices. This study reveals the dual-ion energy storage mechanism of La0.7Bi0.3Mn0.4Fe0.3Cu0.3O3 nano-HEPO in aqueous alkaline BSH devices. The deintercalation of hydrogen cations is hindered during discharge due to surface filling with oxygen vacancies, causing irreversible phase transition and capacity deterioration.