Flower-shaped lithium nitride as a protective layer via facile plasma activation for stable lithium metal anodes

Unstable solid electrolyte interphase (SEI) layer formation and uncontrolled lithium (Li) dendrites growth are two major obstacles that hinder the application of Li metal as the anode in Li batteries. To solve these problems, a multifunctional protective layer was designed for the first time using N₂ plasma activation of the Li metal. A highly [001] oriented and flower shaped Li₃N layer was obtained on the surface of Li metal with a plasma activation time less than 5 min. Due to high Young's modulus (48 GPa) and high ionic conductivity (5.02×10^-1 mS cm^-1), this unique protective layer can physically block the direct contact between reactive Li metal and the liquid organic electrolyte, and suppress the Li dendrites formation. It gives rise to a stable voltage profile with plating/stripping for 30,000 min in a symmetric cell. For Li/LCO full cell, the plasma activated Li₃N electrode shows better capacity retention of more than 96% and higher capacity at a 5 C rate compared to bare Li anode. This plasma activation strategy provides a facile, scalable and efficient approach to realize a safe Li metal battery with superior electrochemical performance.