Models for the Interplay of Mechanics, Electrochemistry, Thermodynamics and Kinetics in Lithium-Ion Batteries

Abstract

The interplay of mechanics, electrochemistry, thermodynamics and kinetics in lithium-ion batteries is summarized. Attention is focused on models for such interactions but is restricted to issues related to all solid-state batteries with lithium metal anodes and a solid electrolyte, as such systems potentially enable higher energy density. Models for diffusion induced stress and fracture due to lithiation swelling and shrinkage are overviewed. Transport models for lithium ions in solid electrolytes are summarized. Mechanical effects are significant in binary ion conducting materials. The effect of stress on the kinetics of lithium flux across electrode-electrolyte interfaces is described. Such constitutive laws are relevant to modeling the morphological stability or instability of the electrode-electrolyte interface. The preceding topics are relatively well developed in regard to modeling. The models that have been developed are fairly successful in terms of agreement with experimental observations, though further work is needed in all areas to explore phenomena that become prominent as technology and materials development advances. An area that is less mature is modeling of the nucleation and growth of lithium filaments in solid electrolytes that lead to cell short circuits. The models that have been developed for this phenomenon are described. They are not fully consistent with the observed behavior of lithium filament and dendrite growth in solid electrolytes. Thus, filament growth and void growth in the lithium metal electrode that is closely connected with filament growth remain open issues that need further model development at a fundamental level.