Electrode–solution interactions in Li-ion batteries: a short summary and new insights

This paper is aimed at reviewing and discussing several selected surface phenomena related to Li-ion batteries. Accumulated data from in situ XRD, in situ AFM, SEM, and electrochemical measurements of graphite electrodes comprising different types of graphite particles (in terms of morphology and 3D structure) converge to a description of failure mechanisms of graphite electrodes, which involve deactivation by insulating surface films that surround cracked particles. It appears that the performance of the cathodes is also, to a large extent, surface film controlled. Hence, aging of Li-ion batteries relates mostly to surface phenomena that increase the electrodes’ impedance, especially at elevated temperatures. Attempts to improve the performance of Li-ion battery systems by introduction of new salts and reactive additives are reviewed. The impact of elevated temperatures (up to 80 °C) is also discussed.