Recycling inactive lithium in lithium-sulfur batteries using organic polysulfide redox

The lifespan of practical lithium-sulfur (Li-S) batteries is hindered by the incessant formation of inactive Li. Recycling inactive Li is a promising strategy to recover Li inventory yet this has never been achieved in Li-S batteries due to the obstacle of Li polysulfides (LiPSs). Herein, organic polysulfide redox is proposed to recycle inactive Li by employing 2-aminophenylacetonitrile (APA) as a redox precursor. APA first reacts with Li and then with S to form an oxidant for recycling inactive Li (O-RIL) by connecting long-chain PSs with the moiety in APA. Then, O-RIL diffuses to the anode side, reacting with inactive Li and generating a reductant for recycling inactive Li (R-RIL) with short-chain LiPSs. The circulation of R-RIL and O-RIL enables continuous redox to recycle inactive Li, which improves the lifespan of Li-S batteries from 40 to 140 cycles under practical conditions. This work demonstrates the importance of recycling inactive Li for developing practical Li-S batteries.