In‐Cavity Lithium Deposition Enabled by Carbon Framework‐Integrated Separator for Stable Low‐Pressure Cycling

ABSTRACT Practical implementation of Li metal anodes has been hindered by non‐uniform, dendritic growth of Li, which causes continuous side reactions, internal short‐circuiting, and early cell failure. Although applying external pressure has been reported to promote dense Li plating to some extent, the practical application of this approach remains limited. Herein, a carbon framework‐integrated separator to regulate the plating–stripping behavior of Li at reduced external pressure is proposed. To ensure both high porosity and mechanical integrity, carbon nanofibers (CNFs) are employed as a model material for realizing the framework‐integrated separator structure. CNFs are electrophoretically deposited onto the separator to achieve a uniform and mechanically robust layer, while preserving the intrinsic porous structure of the separator. Combined experimental and computational studies show that when assembled with a Li metal anode, the carbon framework‐integrated separator enables kinetics‐controlled “in‐cavity” deposition, effectively guiding dense Li plating and accommodating plating‐induced volume changes. As a result, a high‐voltage (4.25 V) and high‐capacity (4.0 mAh cm ⁻² ) full cell exhibits stable cycling under low external pressure (0.26 MPa). This work provides a promising strategy for designing functional separators to realize practical high‐energy‐density Li metal batteries.