In Situ Organoselenization for Ultrastable Li-Se Batteries.

The shuttle effect of lithium polyselenides (Li2Sen) seriously hinders the practical application of lithium-selenium (Li-Se) batteries. Traditional approaches for confining Li2Sen 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 Li2Sen and 2-benzothiazole diethyldithiocarbamate (BTZA) to graft selenium atoms onto the organic framework. Upon charging, organic diselenides are generated, fundamentally eliminating the formation of Li2Sen. 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.