Temperature-Dependent Aging Mechanisms in Commercial Sodium-Ion Batteries

The effect of temperature on aging of commercial Na-ion batteries is investigated quantitatively using commercial 2 Ah 21700-type cells with NFM cathode and hard carbon anode. The cells are cycled at 0.5 C in the temperature range between −10 °C and 45 °C. Interestingly, similar to Li-ion cells, a V-shaped Arrhenius plot of the initial aging rates indicates two different main aging mechanisms below and above 3 °C. Post-Mortem and electrochemical analysis reveal that the dominating aging mechanism for T < 3 °C is most likely Na metal deposition and subsequent reaction of metallic Na metal with electrolyte.