Temperature-driven path dependence in Li-ion battery cyclic aging

Abstract

Operation temperature is known to be one of the most impacting parameters for aging of Li-ion batteries under cycling conditions. While Li plating usually dominates aging at low temperatures, Solid-Electrolyte-Interphase (SEI) growth often dominates aging at elevated temperatures. The longest cycle life for Li-ion batteries is observed at the crossover temperature of both aging mechanisms at around 25 °C. We introduce aging color maps to show changes in the aging rate during battery aging. Reconstructed 3-electrode full cells with Li reference electrode show that the prolonged CV phase during charging at low temperatures counteracts Li plating by an increasing anode potential. Thirty-six temperature variations during cycling between 0 °C and 45 °C were studied to investigate the temperature path dependence of battery aging. The permutability of aging temperatures is analyzed by means of commutators. It turns out that aging at elevated temperatures is only slightly affected by previous aging processes and aging at lower temperatures with Li plating accelerates itself. Previous high temperature cycling decelerates Li plating and shifts its onset to lower temperatures, leading to a new and improved optimum cycling temperature of 20 °C. Differential voltage analysis and Post-Mortem analysis were performed to identify the underlying aging mechanisms.