Mechano-electrochemical and buckling analysis of composition-gradient nanowires electrodes in lithium-ion battery

With the rapid development of lithium-ion batteries, the electrode becomes more and more miniaturized. It is necessary to analyze the stress and axial force in the nanowire electrode. The main work of this paper is to analyze the stresses and buckling in homogeneous material nanowire electrodes and two kinds of composition-gradient (positive gradient and negative gradient) material nanowire electrodes of lithium-ion batteries. Comparing the diffusion-induced stresses (DISs) and buckling in three electrodes, we analyze the advantage of composition-gradient material electrodes on DISs and axial forces. The finite deformation theory and the stress-induced diffusion hypothesis are adopted to establish the constitutive equations, and the nonlinear influence of large deformation is considered. We conclude that ratios of length to radius and constraint conditions have great influence on the buckling of nanowire electrodes. The composition-gradient materials can reduce the stress and prevent the electrode from buckling. Under the same constraint condition, the positive gradient with smaller ratio of length to radius and smaller diffusion flux can delay buckling. When the ratio of length to radius are larger and the diffusion flux is larger, the negative gradient can delay buckling. The results can provide a theoretical guidance on the way of charging operation and the design of electrodes.