Diffusion-induced stress development and stress-enhanced diffusion in amorphous lithium alloy nanowire battery electrodes were investigated using a finite deformation model, accounting for full two-way coupling between diffusion and stress evolution. Analytical solutions were derived using a perturbation method. The analyses revealed significant contributions to the driving force for diffusion by stress gradient, an effect much stronger than those seen in cathode lattices but so far was neglected for alloy-based anodes. The contribution of stress to diffusion was small at low lithium concentrations, this lack of stress-enhanced diffusion leads to significantly higher diffusion-induced stress levels in early stages of a charging cycle. As the lithium concentration increased, stress-enhanced diffusion becomes more pronounced, leading to lower diffusion-induced stress levels. The long-term diffusion-induced stress level in the material scales with charging rate, nanowire radius, and the mobility of Li ions as modulated by the effect of stress. The solutions obtained provide guidance for lowering stresses during charging. In particular, lower charging rates should be used during the initial stages of charging cycles.

Strong Stress-Enhanced Diffusion in Amorphous Lithium Alloy Nanowire Electrodes. Y.F.Gao, M.Zhou: Journal of Applied Physics, 2011, 109[1], 014310