Modeling microstructure evolution in electrochemical systems is vital for understanding the mechanism of various electrochemical processes. We propose a general phase field framework that guarantees that the energy decreases upon evolution in an isothermal system. To handle realistic materials and processing parameters, a driving force extension method is employed. We apply this approach to examine isolated metallic lithium (‘dead’ lithium) formation that is one of the key challenges in enabling the practical application of lithium metal anodes. Our results show that completely suppressing dendrites is unnecessary if they are controllable and do not form isolated metallic lithium. We also examine the effects of intentionally applied external thermal gradients to mitigate dendrite growth on lithium-metal anodes, improving battery safety and lifetime. Small temperature differences produce large thermal gradients across the cell due to the thinness of the separator that can lead to thermodiffusion in the electrolyte. We demonstrate that thermal gradients promote anode stability through preferential lithium deposition at dendrite roots instead of dendrite tips that can fully suppressed dendrite formation. Dendrite growth can also be accelerated unintentionally by the thermal gradient, which provides crucial insight for the design of cell geometries and thermal management.
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