Strong dependency of lithium diffusion on mechanical constraints in high-capacity Li-ion battery electrodes

摘要

The effect of external constraints on Li diffusion in high-capacity Li-ion battery electrodes is investigated using a coupled finite deformation theory.It is found that thinfilm electrodes on rigid substrates experience much slower diffusion rates compared with free-standing films with the same material properties and geometric dimensions.More importantly,the study reveals that mechanical driving forces tend to retard diffusion in highly-constrained thin films when lithiation-induced softening is considered,in contrast to the fact that mechanical driving forces always enhance diffusion when deformation is fully elastic.The results provide further proof that nano-particles are a better design option for nextgeneration alloy-based electrodes compared with thin films.