Dual‐Protective Role of PM475: Bolstering Anode and Cathode Stability in Lithium Metal Batteries

Abstract The increasing demand for high‐energy storage solutions has brought attention to the limitations of commercial Lithium‐ion batteries (LIBs). While Lithium metal batteries (LMBs) hold promise as an alternative, their practical use is hindered by interface instability in both the lithium anode and Ni‐rich layered cathode during cycling. In this study, a cost‐effective is introduced, bifunctional film‐forming additive: polyethylene glycol diacrylate (PM475). PM475, a long‐chain organic molecule rich in oxygen‐containing functional groups, can create a flexible and stable protective interface on both the lithium metal anode and Ni‐rich Li[Ni_xCo_yMn_1−x−y]O₂ (NCM) cathode. This PM475 enhances the solid electrolyte interface (SEI) components on the lithium anode, effectively suppressing the growth of lithium dendrites. Furthermore, it establishes a uniform interface layer on the Ni‐rich NCM cathode, significantly improving battery cycle life. Consequently, the Li||Li symmetric cell can endure 400 h of cycling at 2 mA cm⁻², and the Li||NCM811 full cell exhibits an impressive capacity retention increase from 44.3% to 88.4% after 250 cycles at 1 C under a high cathode load of 20 mg cm⁻². This research highlights PM475 as a highly effective additive for enhancing LMB performance, offering a promising avenue for future high‐energy‐density storage systems.