In situ reactive coating of metallic and selenophilic Ag₂Se on Se/C cathode materials for high performance Li-Se...

A facile methodology to fabricate a metallic and selenophilic Ag₂Se coating on a Se/nitrogen-doped mesoporous carbon composite, has been successfully developed based on the in situ redox reaction between Se and AgNO₃ under ambient conditions. The in situ reactive growth of Ag₂Se on Se ensures the complete encapsulation of Se by the Ag₂Se coating, which endows the Ag₂Se coating with the dual effects of physical entrapment and chemical binding to effectively confine polyselenide intermediates within the cathodes. With the further assistance of mesopore confinement of the nitrogen-doped carbons, the Ag₂Se-coated Se/nitrogen-doped mesoporous carbon composites present much improved electrochemical performances with a high initial discharge capacity of 652 mA h g^-1, a high coulombic efficiency of 95.4% and a high reversible capacity of 382 mA h g^-1 after 100 cycles. These encouraging results suggest that the in situ reactive construction of metallic and chalcogenophilic coating layers on the chalcogen (e.g. S, Se and Te)-based electrode materials should be a promising and easy to scale-up method for practical applications of lithium batteries in light of the very simple in situ reaction processes involved.