Radiation Chemistry as a Tool to Accelerate and Predict Calendar Ageing in Lithium-Ion Batteries

Electrochemical energy storage systems such as batteries are in a resting mode most of the time. Even when no current is passing through them, they undergo ageing phenomena, more or less detrimental to their lifespan, known as calendar ageing. Limiting these ageing processes requires a better understanding of them, but studies on calendar ageing are generally time-consuming. Here, we show that radiolysis, i.e. chemistry induced by ionizing radiation, generates similar degradation compounds and can significantly accelerate calendar ageing phenomena (by a factor of 30 under our experimental conditions). Using electrochemical impedance spectroscopy (EIS), we studied symmetrical coin cells containing an electrolyte between two identical electrodes, with or without various additives commonly used in batteries. EIS makes it possible to monitor the change in resistance in the device over time and therefore the formation of the electrode/electrolyte interphase and the charge transfer kinetics. Among the various additives tested (vinylene carbonate, fluoroethylene carbonate and ethyl acetate), the first two proved to be those with the best properties for the cell as a whole. In all cases, just a few hours of irradiation were sufficient to simulate the equivalence of several weeks of calendar ageing.