Engineering the Interphase via Active Learning-Guided Charging for Stable Anode-Free Batteries

Anode-free lithium metal batteries promise exceptional energy density but suffer from unstable lithium plating and a short cycle life. While pulse charging is known to influence deposition morphology, we demonstrate it can also reshape the local solvation environment at the electrode interface─without altering bulk electrolyte composition─to favor anion-derived solid electrolyte interphase (SEI) formation. By integrating electrochemical insight with Bayesian optimization, we rapidly identify high-performance pulse protocols in one month─five times faster than conventional screening. The optimal protocol boosts the cycle performance by over 60%, enabling uniform lithium deposition and a LiF-rich SEI. Molecular simulations reveal that the pulse charging enhances specific anion coordination in the lithium-ion solvation structure, rationalizing the SEI chemistry. Crucially, the same design strategy transfers successfully to a different electrolyte system, underscoring its generality. This work establishes intelligent charging as a powerful, chemistry-agnostic tool for interfacial engineering in next-generation batteries.