Two-phase versus two-stage versus multi-phase lithiation kinetics in silicon

We classify the lithiation process into three types, namely, two-phase, two-stage, and multi-phase lithiation. We found that under a given charging rate, smaller electrochemical Biot number of β will likely to result in two-phase lithiation, while larger β may lead to multi-phase lithiation. For the film anode, intermediate β, or intermediate charging rate, will yield two-stage lithiation, and the Li concentration during the first stage of the lithiation is determined by the relationship between β and the charging rate (or more precisely the Li flux supplied to the Si/Li_xSi phase interface). Such two-stage lithiation does not occur in the particle or fiber anode.