Chemo-mechanical modeling of elastic thin-film electrodes on elastic substrates under chemical equilibrium

High-capacity anodes hold great promise for the next-generation lithium-ion batteries. However, they are well known to suffer from mechanical failure during battery cycling. Among various nano-structured electrodes, nano-scale thin-film electrodes have been frequently observed to undergo fracture and delamination. In this work, we investigate the effect of nonlinear coupling between chemical and mechanical fields on the distribution of solute concentration and stress in a finite thin-film elastic electrode bonded to the surface of a thick chemically-inactive elastic substrate. The film is considered in chemical equilibrium with an external mass reservoir. It is demonstrated through numerical and analytical methods that chemo-mechanical coupling could lead to considerable solute segregation at the edges of the film. The coupling could also remarkably magnify the edge stress intensity factor beyond the classical predictions in the absence of coupling. Potential implications of the results in terms of prediction of a critical film thickness to avoid film delamination, and in terms of prediction of fatigue delamination growth are also discussed.