Diffusion-induced stress and delamination of layered electrode plates with composition-gradient

Diffusion-induced stress can result in failure of layered electrodes in lithium-ion batteries during the process of fast lithiation and delithiation. Recent studies have demonstrated that the electro-chemo-mechanical properties of compositions-gradient nanoparticles are superior to those of homogeneous ones. In light of this aspect, we develop a theoretical model to probe the effects of composition-gradient on the stress evolution in layered electrodes. Our analysis concludes that, compared with the corresponding homogeneous structure, symmetrical negative-exponent gradient active plates or positive-exponent gradient bilayer electrodes can significantly reduce the maximum compressive stress and the stress drop at the electrode-collector interface, while the energy release rate of interface delamination is slightly weakened by it. These results, again, show that the composition-gradient could improve the mechanical performance of electrodes in lithium-ion batteries, and are instrumental to the design of electrode structures.