Enabling the Multiscale Interfacial Stabilization for Ah-level Anode-free Lithium Metal Battery via a Prelithiation Separator strategy

Abstract Featuring the straightforward assembly of fully lithiated cathodes with bared current collectors, anode-free lithium metal batteries (AFLMBs) nominally achieve the highest gravimetric/volumetric energy densities with minimum Li host in excess, simplified anode processing, as well as the reduced labor/cost of cell manufacturing and maintenance. Nevertheless, issues of parasitic interfacial reactions, high-voltage cathode collapse and the irreversible Li⁺ plating on the deposition substrate, collectively deplete the cation reservoir of cell models. This study thus proposes a separator strategy to enable the multiscale interfacial stabilization for Ah-level AFLMB model. Specifically, the sacrificial Li₂S@C prelithiation layer loaded on the polyolefin separator (Li₂S@C|PE), not only supplements the customized Li⁺ inventory during the formation cycle, but also establishes the lithium polysulfides containing cathode interface with the high-voltage tolerance (till 4.5V). Through the combined analysis of in-situ electrochemical impedance spectroscopy and transmission-mode operando X-ray diffraction, the enhanced Li⁺ diffusivity and reversible phase evolution of LiNi0.8Co0.1Mn0.1O₂ cathode as in contact with the prelithiation separator are real-time documented. Upon the cell assembly of Li₂S@C|PE separator with the Ag modified Cu foil (Ag-Cu) and densely-packed LiNi0.8Co0.1Mn0.1O₂ cathode (25.0 mg cm⁻ ²) under lean electrolyte condition (E/C 1.8 g Ah⁻ ¹), the 1.22 Ah pouch-format prototype balances the robust cycling endurance, gravimetric/volumetric energy densities of 450 Wh kg⁻ ¹/1355 Wh L⁻ ¹, as well as extreme power output up to 830.6 W kg⁻ ¹. This prelithiation protocol demonstrates upscaling potential and generic applicability to secure the interfacial chemistries for anode-less/-free LMB configurations.