EV battery retains 78% capacity after 200 cycles using stretch trick

Researchers at Ulsan National Institute of Science and Technology (UNIST) have developed a novel method to enhance the lifespan and safety of solid-state batteries by physically stretching a fluorinated polymer electrolyte (PVDF-TrFE-CFE). This uniaxial stretching aligns the polymer chains, creating continuous pathways that significantly improve lithium-ion transport. As a result, batteries using the stretched electrolyte retained about 78% of their capacity after 200 charge-discharge cycles, compared to only 55% retention with unstretched electrolytes. The lithium-ion diffusion rate increased nearly fivefold, and ionic conductivity improved by 72%. Additionally, incorporating ceramic powder (LLZTO) into the polymer matrix enhanced mechanical flexibility, flame retardancy, and ion conductivity. Safety tests demonstrated that the new electrolyte is highly flame-retardant, extinguishing flames within four seconds, addressing a major safety concern in electric vehicle batteries that use flammable organic liquid electrolytes. The team validated the practical application by integrating the stretched electrolyte into