Meaning
Phase transition involving the aggregation of isolated lithium atoms into metallic clusters or nanoparticles. This process occurs when the rate of lithium ion reduction exceeds the rate of intercalation into the host material. Lithium cluster condensation is a precursor to the formation of larger dendrites which can penetrate the separator and cause internal short circuits.
Nucleation Energy
Formation of a new metallic phase requires overcoming a thermodynamic barrier at the electrode surface. During lithium cluster condensation, small groups of atoms stabilize to form a nucleus. The size of these nuclei depends on the local current density and the properties of the electrolyte interface.
Growth Morphology
Shape and distribution of the metallic deposits are determined by the movement of ions in the vicinity of the cluster. Once lithium cluster condensation begins, the resulting clusters act as high-field sites that attract more ions. This leads to non-uniform growth patterns that are difficult to reverse during discharge.
Cycle Efficiency
Reversibility of the battery is reduced when metallic lithium forms instead of entering the anode lattice. Lithium cluster condensation results in dead lithium that no longer participates in the electrochemical reaction. This loss of active material causes the capacity of the cell to fade over time.
The formation of these inactive zones represents a permanent reduction in the energy storage potential of the pack.
