Stable Lithium Plating and Stripping Enabled by a LiPON Nanolayer on PP Separator

The practical application of the Li metal anode (LMA) is hindered by its low coulombic efficiency and dendrite formation. Although solid‐state electrolytes hold promise as ideal partners for LMA, their effectiveness is limited by the poor workability and ionic conductivity. Herein, a modified separator combining the rapid Li+ transport of a liquid electrolyte and the interfacial stability of a solid‐state electrolyte is explored to realize stable cycling of the LMA. A conformal nanolayer of LiPON is coated on a polypropylene separator by a scalable magnetron sputtering method, which is compatible with current Li‐ion battery production lines and promising for the practical applications. The resulting LMA–electrolyte/separator interface is Li+‐conductive, electron‐insulating, mechanically and chemically stable. Consequently, Li|Li cells maintain stable dendrite‐free cycling with overpotentials of 10 and 40 mV over 2000 h at 1 and 5 mA cm‐2, respectively. Additionally, the Li|LiFePO4 full cells achieve a capacity retention of 92% after 550 cycles, confirming its application potential. By coating a nanolayer of LiPON through a scalable magnetron sputtering method, a modified polypropylene separator combining the rapid Li+ transport of liquid electrolytes and the interfacial stability of solid‐state electrolytes is achieved, which abates harmful side‐reactions, and realizes the stable cycling of lithium metal anode without dendrite formation.