Important Role of Atom Diffusion in Dendrite Growth and the Thermal Self-Healing Mechanism

The high self-diffusion barrier of lithium inevitably triggers catastrophic lithium dendrites, creating a safety hazard and hindering the practical application of lithium metal batteries. Experimental studies have observed thermal self-healing of lithium dendrites, but numerical simulations often ignore lithium-atom diffusion, which is detrimental to elucidating the mechanism of thermally induced dendrite self-healing. We develop a phase-field model with atom diffusion and heat transfer modules to investigate the role of atom diffusion in dendrite growth and thermally induced dendrite self-healing. The results show that atom diffusion can induce surface self-healing (weakening the protrusions) and bulk self-healing (dissipating the voids) and optimize the dendritic profile; thus, it should be incorporated. The atom diffusion accelerated by high temperature exhibits strong healing-dendrite properties and achieves the thermal self-healing of dendrites. Moreover, our model precisely predicts the threshold temperature of 55 °C above which the dendrites achieve thermal self-healing, consistent with the experimental observations. This work deeply describes the thermal self-healing mechanism of lithium dendrites, which provides potential strategies for managing temperature and effectively suppressing dendrite growth in lithium batteries.