Pulse Current Derived Gradient Inorganic‐Rich SEI Layer Achieving Uniform Lithium Deposition

ABSTRACT

Loading uniform lithium metal onto the collector while obtaining a durable solid electrolyte interphase (SEI) layer is considered a challenging process in lithium metal anode manufacturing. In this study, a pulse‐current deposition (PCD) was applied to load lithium onto collectors without introducing redundant chemical components. It was demonstrated that the high overpotential generated by pulsed current leads to fine, uniform crystal nuclei, which is the core mechanism for achieving collector‐smooth‐covering ability. More importantly, the SEI formed by PCD exhibited a distinct gradient, inorganic‐rich and thinner SEI layer, which leads to fast ion‐transfer dynamics. It was found that a high electric field strength produced by PCD leads to a hierarchical distribution of polar molecules. Besides, the electrolyte component's different reduction stability leads to different decomposition sequences. By adjusting the pulse current density, the PCD process protocol (10 mA cm ⁻² ) with the highest deposition and stripping efficiency is optimized. Compared with conventional constant‐current deposition (CCD), the PCD‐loaded anode exhibits significantly improved electrochemical performance (2800 h symmetrical cell cycle life at 1 mA cm ⁻² , 1 mAh cm ⁻² ; 80.14% capacity retention over 500 cycles in LFP full cell, with the N/P ratio of 2), while the processing time is substantially reduced by 89.8%.