Effect of charging rate on Arrhenius plots describing optimum cycle life for pouch and cylindrical cells

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Effect of Charging Rate on Arrhenius Plots describing Optimum Cycle Life for Pouch and Cylindrical Cells[1]
Temperature affects the chemical reactions in a Li-ion battery and consequently influences the aging rate of the cell [2,3]. Two temperature dependent mechanisms influence the aging on the anode side: solid electrolyte interface (SEI) growth at high temperatures and Li plating at low temperatures. These two mechanisms limit the cycle life. Li-ion cell show the best cycling life in the temperature region where both of these two mechanisms are minimum.
It was shown experimentally [2] and theoretically [3] that the temperature dependent aging of Li-ion cells follows the Arrhenius law (𝑟=𝐴exp(-𝐸𝑎/𝑘𝐵T) in which 𝐴: pre-exponential factor, 𝐸𝑎: activation energy, 𝑘𝐵: Boltzmann constant, and T: absolute temperature) with two different slopes for low and high temperatures. The slope at high temperature corresponds to the SEI growth as the dominating aging mechanism while the slope at low temperature corresponds to Li plating as the main aging mechanism. The minimum of this plot is where these two lines coincide. It shows the temperature at which the both, SEI growth and Li plating, are minimum and the cell has its longest cycle life.
In this poster, we show experimentally for lab-made pouch cells and for commercial 21700 cylindrical cells that this optimum temperature is shifting to higher temperatures with increasing the charging C-rate. Furthermore, we find that as the anode coating thickness increases (going from high-power to high-energy cells), the transition to Li plating starts at higher temperatures. In other words for high-energy cells the optimum temperature for longest cycle life shifts to higher temperatures. Furthermore, we have shown that this optimum temperature is a function of state-of-health (SoH) of the cell.
[1] M. Bozorgchenani et al., J. Electrochem. Society 2022, 169, 030509, doi: 10.1149/1945-7111/ac580d
[2] T. Waldmann et al., J. Power Sources 2014, 262, 129, doi: 10.1016/j.jpowsour.2014.03.112
[3] X.-G Yang et al. J. Power Sources 2018, 402, 489, doi: 10.1016/j.jpowsour.2018.09.069

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