Effect of composite gradient materials on the electrochemo-mechanical performance of cylindrical electrode particles

Extensive evidence has demonstrated that electrode structures based on composite gradient materials exhibit excellent charging efficiency and cycling stability. This study develops an electrochemo-mechanical coupling model for cylindrical electrode particles composed of composite gradient materials and investigates the effects of two types of gradients (positive and negative) on the stress field, chemical field, and buckling behavior. The results show that the influence of composite gradient materials on the stress field shows an obvious size effect. Composite gradient materials are unsuitable for small-sized electrode particles, which increase stress levels and elevate the risk of mechanical failure. For large-sized particles, negative gradient materials reduce global internal stresses, providing a safer mechanical environment. Moreover, relative to homogeneous materials, positive gradient materials enhance the buckling resistance and negative gradient materials enhance the lithiation efficiency of cylindrical electrode particles. Therefore, the composite gradient design effectively improves the electrochemo-mechanical performance of electrode particles. Designers can choose either a positive gradient or negative gradient design strategy according to the design objectives.