Journal of Power Sources, Vol.288, 278-287, 2015
Solute segregation and stress intensity factors at the edge of elastic thin-film electrodes under chemical equilibrium
High-capacity anodes hold great promise for the next-generation lithium-ion batteries. However, such electrodes are known to suffer from mechanical degradation during battery cycling. One important failure mode commonly observed in thin-film electrodes is film delamination from the underneath current collector. Here, by accounting for the nonlinear coupling between the chemical and mechanical fields, we derive the stress intensity and solute segregation factors close to the edge of a thin elastic film which is bonded to the surface of a thick elastic substrate. The film is considered in chemical equilibrium with an external mass reservoir. While in the limit of extremely weak coupling, our formulation reduces to the classical delamination theory, the results indicate that the chemo-mechanical coupling leads to magnification of the stress intensity factor and solute segregation near the film edge. The effect of coupling on the solute and stress distribution in the film is discussed. Further, an analytical expression is derived for the edge stress intensity factor in the limit of extremely strong chemo-mechanical coupling, based on which a modified critical film thickness to avoid edge delamination is proposed. Potential implication of the results for fatigue delamination growth is also discussed. (c) 2015 Elsevier B.V. All rights reserved.