In Situ Organoselenization for Ultrastable Li−Se Batteries

ABSTRACT The shuttle effect of lithium polyselenides (Li ₂ Se _n ) seriously hinders the practical application of lithium−selenium (Li−Se) batteries. Traditional approaches for confining Li ₂ Se _n cannot fundamentally resolve this issue. In this work, we adopt a strategy of in situ conversion of inorganic selenium into organic forms, which utilizes the nucleophilic reaction between Li ₂ Se _n and 2−benzothiazole diethyldithiocarbamate (BTZA) to graft selenium atoms onto the organic framework. Upon charging, organic diselenides are generated, fundamentally eliminating the formation of Li ₂ Se _n . Furthermore, lithium benzothiazole sulfide (BTSLi) is concurrently produced during the organification process. It is converted to the redox−active 2,2′−dibenzothiazole disulfide (BTDS) during charging, compensating for the capacity loss resulting from the C−Se bond formation. Moreover, the organoselenium products exhibit high discharge voltages and strong lithium−ion transport capability, enhancing the energy density and reaction kinetics of the battery. The Li−Se cell with BTZA maintains a capacity retention of 92.87% after 1300 cycles at 2 C. The pouch cell with a capacity of 0.6 Ah can be stably operated for 30 cycles at 0.1 C. Excellent electrochemical performances are also achieved at high rates. This work presents a novel strategy for achieving highly stable Li−Se battery.