Realizing Persistent Lithium Protection and Revival with Dissolution-Equilibrium-Driven Sustainable Additives...

Additive chemistry plays a pivotal role in enhancing the cycling stability of lithium metal batteries. Conventional additives with high solubility facilitate the formation of a stable interface in the early stages of cycling, yet typically act as "sacrificial agents", failing to maintain a durable interface over long time. Herein, we demonstrate a sustainable lithium protection and retrieval strategy based on additive reservoirs driven by chemical dissolution equilibrium. A sparingly soluble AgI coating on the separator provides a continuous supply of constant concentration of Ag⁺ and I^-, where Ag⁺ contributes to the formation of a Li-Ag alloy interphase, promoting uniform Li deposition, while I^- assisting in the recovery of inactive Li. With this strategy, symmetric Li||Li batteries deliver an extended cycle life over of 1000 h at 5 mA cm^-2 with a capacity of 5 mAh cm^-2. Additionally, practical pouch cells demonstrate a prolonged cycle life of over 200 cycles with 82% capacity retention. This work offers new insights into additive chemistry and paves the way for the development of durable lithium metal batteries.