German scientists develop safer, high-energy battery film for EVs

German researchers at Fraunhofer FEP have developed a novel metal-on-polymer current collector for lithium-ion batteries, aimed at enhancing both safety and energy density in electric vehicles (EVs). Using a roll-to-roll electron beam evaporation process, they coat polymer films with thin layers (up to 1 µm) of aluminum or copper on both sides, creating lightweight, wrinkle-free films that match the thickness and conductivity of traditional metal foils. This innovation reduces battery weight, thereby increasing energy density, and introduces an integrated safety feature: if a short circuit occurs, the polymer substrate melts, instantly interrupting the current flow and preventing thermal runaway—a major cause of EV battery fires. The new current collectors were successfully integrated into pouch cells by TU Braunschweig and demonstrated electrochemical performance and cycle stability comparable to conventional cells across various charging and discharging rates. This scalable manufacturing method offers a promising pathway for producing safer, higher-capacity lithium-ion batteries, potentially enabling longer-lasting consumer electronics and extended-range electric