In Situ Organoselenization for Ultrastable Li-Se Batteries

The shuttle effect of lithium polyselenides (Li₂Se_n) seriously hinders the practical application of lithium-selenium (Li-Se) batteries. Traditional approaches for confining Li₂Se_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 Li₂Se_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 Li₂Se_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.