Effect of electrochemical and mechanical properties of SEI on dendritic growth during lithium deposition on lithium metal electrode

Lithium metal represents the optimal candidate for the negative electrode, due to its high theoretical capacity (3860 mAh g−1) and low potential (−3.04 V compared to the standard hydrogen electrode). On the other hand, the major drawback of this technology is the formation of dendrites, which can cause thermal runaway and internal short-circuits, and are responsible for the limited lifetime of the cell. A dendrite-free lithium deposition is needed to improve this technology, thus, a deeper understanding of the phenomena and parameters that influence dendrite growth and formation is necessary. For the first time, the proposed model studies the influence of Solid Electrolyte Interphase (SEI) and its mechanical and electrochemical properties on the dendritic growth. Starting from the initial surface geometry and the electrochemical and mechanical properties of the components, the model can predict the conditions that favours dendritic growth and distinguish different surface morphologies depending on the applied current density. Moreover, the addition of the SEI mechanics allows the model to distinguish between tip-induced growth and root-induced growth, which is still not fully understood and has not been modelled yet.