Reconstruction of the Solid Electrolyte Interphase through an In-Situ Periodic Healing Strategy in Anode-Free Lithium Metal Batteries

Abstract

Anode free Li-metal batteries (AFLMBs) provide a significantly higher specific energy density than traditional Li-ion batteries but suffer from rapid capacity fade. The solid electrolyte interphase (SEI) on the Cu current collector degrades to a fragile and less dense SEI during repeated Li plating/stripping, leading to uncontrolled electrolyte decomposition and uneven Li deposition. To address this, we present a periodic healing strategy to reconstruct in situ deteriorative SEI at low current density, resulting in an SEI enriched with inorganic species to enhance ion transport and mitigate parasitic reactions. Instead of localized dendrite growth, lithium deposition occurs through an interconnected process, resulting in a smoother, more uniform surface attributed to the healed SEI. Consequently, Li–Cu cells exhibit a remarkable 99.2% average Coulombic Efficiency (CE) over 500 cycles at 1 mA cm^–2. The efficiency of this periodic healing strategy is observed across various electrolyte systems and further demonstrated in high-performance AFLMBs using LiFePO₄ and LiNi_xCo_yMn_1-x-yO₂ cathodes, achieving enhanced cumulative energy output and highlighting its great practical potential.