Analytical model of Li-ion diffusion-induced stress in nanowire and negative Poisson's ratio electrode under different operations

Diffusion-induced stress is one of the critical challenges in developing lithium ion battery technologies, which may lead to the huge volume expansion, nucleation of cracks, electrode mechanical degradation and even pulverization. It has been testified nanostructured electrodes with the consideration of surface effect and property of negative Poisson's ratio can restrain volumetric expansion generation and relieve the hazard of stress-induced crack nucleation. In this paper, an analytical model of diffusion-induced stress for nanowire electrode under different operations is established and a relationship between stress and the nanowire radius is formed. Through changing the morphology of nanowire electrode, the stress equations for negative Poisson's ratio electrode can be obtained. By comparing surface effect influence on diffusion-induced stress between the nanowire and negative Poisson's ratio electrodes under different operations, it is found diffusion-induced stress, especially the tensile stress, can be decreased greatly and even converted to compressive one by the nanostructured electrode and the mechanism of negative Poisson's ratio, which may improve the mechanical property of battery and be in good agreement with experimental observations. Our work provides reference conditions for the improvement of battery to mitigate the mechanical degradation and prolong the cycle life as well as avoid failure.