Misfit dislocations induced by lithium-ion diffusion in a thin film anode

Abstract

According to the diffusion kinetics and heteroepitaxial strained layer theory, this paper presents a theoretical model to investigate the generation and distribution of misfit dislocations in a thin film anode under galvanostatic and potentiostatic operations. The results show that the nucleation and density distribution of misfit dislocations largely depend on the thickness of the diffused layer and insertion time. When the thickness is less than a certain critical value, the total strain energy in the electrode is almost insusceptible and yet reduced by misfit dislocations for that of going beyond the critical value. Under potentiostatic operation, the rise range and response speed of the dislocation density are greater and faster. A certain region immediately possesses much lower dislocation density under the electrode surface compared with the region below it. These quantitative results can provide a new perspective into relieving diffusion-induced stress by misfit dislocations with the purpose of improving the mechanical durability of lithium-ion batteries.