Lithiophilic Ni2P@NCNT Interlayer for Uniform Li-Ion Flux and Stable Lithium Metal Batteries

Lithium metal anodes are critical for advancing high-energy-density lithium secondary batteries due to their exceptionally high theoretical specific capacity. However, the uncontrolled growth of lithium dendrites may penetrate the separator, thereby limiting the practical application of lithium metal anodes. In this work, we report a modified commercial PP separator by incorporating a lithiophilic interlayer composed of Ni2P nanoparticles wrapped with nitrogen-doped carbon nanotubes. The Ni2P@NCNT functionalized separators exhibit high lithium-ion conductivity and enhanced electrolyte wettability, which improve lithium-ion (Li+) transport, promote uniform lithium deposition, and inhibit dendritic growth. Furthermore, DFT calculations reveal a stronger interaction between Li atoms and Ni2P@NCNT, providing energetically favorable deposition sites and leading to uniform, compact Li plating. The Li||Cu cell incorporating Ni2P@NCNT/PP demonstrates stable cycling over 300 cycles at a current density of 0.5 mA cm-2. Meanwhile, the Li||Li symmetric cell achieves an extended operational lifespan of 1500 h under 0.5 mA cm-2. Additionally, the LFP||Li cell demonstrates an extremely low capacity degradation rate of 0.07% per cycle at 0.5 C, showing promising cycling performance. This study introduces a novel approach for designing functional lithiophilic interlayers, providing new perspectives on effectively mitigating Li dendrite formation in lithium metal batteries.