Cell Aging and Voltage Decay

An ES has an unlimited shelf life when stored in a discharged state, but aging does occur and typically decreases the capacitance and increases the resistance. The life of an ES specified by industry standards is a 20% decrease 

Cell or stack aging is indicated by a loss in overall performance due to diminishing capacitance, slower charging and discharging rates, and increased series resistance. In addition, these signs can also be associated with macroscopic phenomena, for example, localized detachment of electrode materials from the metallic collector through electrode swelling, gas evolution, and loss of elements involved in faradic reactions. 

Arrhenius plots of measured leakage currents of EDLC evaluated at a range of voltages. Initially maintained at 60°C for 100 hours at each voltage, the temperature then stepped down from -20 to -40°C. Measurements taken after 10 hr constant conditions. (Source Kotz, R., M. Hahn, and R. Gallay. 2006. Journal of Power Sources, 154, 550-555. With permission.) 

Changes in the chemical properties of an ES material are largely responsible for the aging and voltage decay, in particular, by increasing the temperature 

Commercially Available Electrochemical ESs Used for Cell Aging Analysis 

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