An Ion‐Management Membrane with Vertically Aligned Uniform Electronegative Nanochannels Toward Dendrite‐Free Lithium Metal Anodes

Abstract Lithium (Li) metal anodes have received sustained attention due to their remarkable theoretical specific capacities and low electrochemical potentials. However, the nucleation and growth of Li dendrites during cycling have hindered their application in Li metal batteries (LMBs). As an indispensable battery component, separators offer an ideal platform for mitigating Li dendrites. Herein, an ion‐management membrane (IMM) concept utilizing polydopamine (PDA)‐modified polyetherimide track‐etched membranes (PEITEMs) is proposed. The PDA@PEITEM‐based IMM features vertically aligned uniform electronegative nanochannels, serving as ion distributors and “Li‐ion guides” to simultaneously smooth ion concentration fluctuations and accelerate Li + selective conduction. The IMM's unique structural and chemical properties yield exceptional ionic conductivity (0.73 mS cm −1 ) and high Li + transfer number (0.80) while minimizing Li + concentration fluctuations. When employed in Li/Cu cells, the IMM facilitates a Coulombic efficiency exceeding 96% over 100 cycles at 0.5 mA cm −2 . Moreover, it extends the cycle lifespan of Li/Li cells to 1 200 h at 1.0 mA cm −2 . For Li/LiFePO 4 cells, this approach enables a specific capacity of 146 mAh g −1 , maintaining capacity retention of 79.84% after 1 000 cycles. This novel strategy for constructing free‐standing functional separators is convenient, efficient, and scalable, providing valuable insights into multifunctional separators for dendrite‐free LMBs.