Realizing Persistent Lithium Protection and Revival with Dissolution‐Equilibrium‐Driven Sustainable Additives Reservoir

Additives 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, but typically act as “sacrificial agents”, failing to maintain a durable interface over extended cycles. Herein, we demonstrate a sustainable strategy for lithium protection and retrieval, driven by an additive reservoir regulated by chemical dissolution equilibrium. A sparingly soluble AgI coating on the separator enables the continuous release of Ag⁺ and I⁻ ions. The Ag⁺ ions facilitate the formation of a Li‐Ag alloy interphase, promoting uniform lithium deposition, while the I⁻ ions assist in the recovery of inactive lithium. With this strategy, symmetric Li||Li batteries deliver an extended cycle life over 1000 hours at 5 mA/cm2 with a capacity of 5 mAh/cm2. Additionally, practical pouch cells demonstrate a prolonged cycle life 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.