Lithiophilic TiN interlayer enabling uniform lithium deposition for lithium metal batteries

The practical application of lithium metal anodes is severely impeded by lithium dendritic growth and unstable solid electrolyte interphases (SEI). Herein, we address these challenges through a TiN nanopowder modified separator designed to synergistically regulate interfacial chemistry and lithium deposition behavior. Specifically, the lithiophilic TiN interlayer promotes the formation of an inorganic-dominated SEI comprising LiF, Li 3 N, and Li 2 O, which contributes to a significantly enhanced Li + transference number (from 0.35 to 0.72) and a more homogeneous electric field distribution. These improved interfacial conditions, in turn, effectively regulate the Li + deposition behavior and suppresses parasitic reactions. Consequently, the strategy enables a critical current density of 2.7 mA cm −2 and sustains stable lithium plating-stripping for over 400 h in symmetric Li||Li cells at 1 mA cm −2 . When paired with a high-loading LiFePO 4 cathode (8 mg cm −2 ), the full cell demonstrates a capacity retention of 83.8 % upon 300 cycles at 1 C. By integrating lithiophilic modification with SEI engineering, this separator-driven strategy provides a viable pathway toward the realization of safe, high-energy lithium metal batteries.