A modified separator for a high-energy lithium metal-based electrochemical cell and methods of formation relating thereto are provided. The modified separator includes a substrate including a dopant and a coating layer disposed on the doped substrate. The dopant and compound comprising the coating layer are independently selected from the group consisting of: aluminum oxide (Al2O3), titanium dioxide (TiO2), zirconium dioxide (ZrO2), zinc oxide (ZnO), iron oxide (Fe2O3), tin oxide (SnO), silicon oxide (SiO2), tantalum oxide (Ta2O5), lanthanum oxide (La2O3), hydrofluoroolefin (HfO), cerium oxide (CeO2), and combinations thereof.