Temperature Dependence of Dendritic Lithium Electrodeposition: A Mechanistic Study of the Role of Transport Limitations within the SEI

The accelerated failure of rechargeable Li-metal batteries due to dendritic Li electrodeposition particularly during charging at low temperatures is not well-understood. In this work, we investigate the effect of temperature on the initiation of Li dendrites during galvanostatic lithium electrodeposition. Using electrochemical measurements coupled with optical microscopy, we show that the dendrite onset time increases monotonically with temperature in the range 5 degrees C-35 degrees C. This observation is explained by incorporating temperature effects into an analytical transport model for Li dendrite initiation [J. Electrochem. Soc., 165, D696 (2018)], which considers solid state Li+ diffusion through a gradually thickening solid electrolyte interphase (SEI) layer. We conclude that sluggish Li+ transport at lower temperatures accelerates the depletion of Li+ at the Li-SEI interface, and this effect causes earlier initiation of dendrites at lower temperatures. Electrochemical impedance spectroscopy measurements of the temperature-dependent transport properties of the SEI, as well as plating efficiency measurements, are used to support the model. (C) 2020 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited. The accelerated failure of rechargeable Li-metal batteries due to dendritic Li electrodeposition particularly during charging at low temperatures is not well-understood. In this work, we investigate the effect of temperature on the initiation of Li dendrites during galvanostatic lithium electrodeposition. Using electrochemical measurements coupled with optical microscopy, we show that the dendrite onset time increases monotonically with temperature in the range 5 degrees C-35 degrees C. This observation is explained by incorporating temperature effects into an analytical transport model for Li dendrite initiation [J. Electrochem. Soc., 165, D696 (2018)], which considers solid state Li+ diffusion through a gradually thickening solid electrolyte interphase (SEI) layer. We conclude that sluggish Li+ transport at lower temperatures accelerates the depletion of Li+ at the Li-SEI interface, and this effect causes earlier initiation of dendrites at lower temperatures. Electrochemical impedance spectroscopy measurements of the temperature-dependent transport properties of the SEI, as well as plating efficiency measurements, are used to support the model. (C) 2020 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited.